Thio Derivatives of Imidazol-1-Yl Carboxamides

The invention relates to new chemical compounds, pesticidal compositions containing the new compounds as active ingredient, and the use of the new compounds to control pests.

According to one feature of the invention there is provided a new group of compounds which may be represented by the general formula ##STR2## in which X is oxygen or sulphur, R.sup.3 is hydrogen, alkyl, alkenyl or optionally substituted alkylthio, alkenylthio, aralkylthio, alkoxyalkyl or alkylthioalkyl, R.sup.4 is alkyl or cycloalkyl, and (a) R.sup.1 and R.sup.2 are each lower alkyl or lower alkenyl (b) R.sup.1 is lower alkyl and R.sup.2 is alkoxyalkyl or lower haloalkyl, or (c) R.sup.1 and R.sup.2, together with the nitrogen atom to which they are attached, form a heterocyclic ring, optionally containing 1 to 4 lower alkyl substituents attached to carbon atoms of the heterocyclic ring, selected from morpholino, thiamorpholino, 1-pyrrolidinyl and 1-piperidino; and salts thereof.

Of these compounds a particular group is one in which X is oxygen or sulphur, R.sup.3 is hydrogen, alkyl, alkenyl, alkylthio, alkenylthio, aralkylthio or alkoxyalkyl, R.sup.4 is alkyl or cycloalkyl, and (a) R.sup.1 and R.sup.2 are each lower alkyl or lower alkenyl, (b) R.sup.1 is lower alkyl and R.sup.2 is alkoxyalkyl or lower haloalkyl, or (c) R.sup.1 and R.sup.2, together with the nitrogen atom to which they are attached, form a heterocyclic ring, optionally containing 1 to 4 lower alkyl substituents attached to carbon atoms of the heterocyclic ring, selected from morpholino, thiamorpholino, 1-pyrrolidinyl and 1-piperidino.

A further group of compounds is one in which X is oxygen or sulphur, R.sup.3 is optionally substituted alkylthio, alkenylthio, aralkylthio, alkoxyalkyl or alkylthioalkyl, R.sup.4 is alkyl or cycloalkyl and (a) R.sup.1 and R.sup.2 are each lower alkyl or lower alkenyl (b) R.sup.1 is lower alkyl and R.sup.2 is alkoxyalkyl or lower haloalkyl, or (c) R.sup.1 and R.sup.2 together with the nitrogen atom to which they are attached, form a heterocyclic ring, optionally containing 1 to 4 lower alkyl substituents attached to carbon atoms of the heterocyclic ring, selected from morpholino, thiamorpholino, 1-pyrrolidinyl and 1-piperidino; and salts thereof. Of these compounds a particular group is one in which R.sup.3 is alkylthio, alkenylthio, aralkylthio or alkoxyalkyl.

A preferred group of compounds is one in which (a) R.sup.1 is methyl and R.sup.2 is lower alkyl or lower alkenyl, (b) R.sup.1 and R.sup.2 are both ethyl, propyl or allyl, or (c) R.sup.1 and R.sup.2, together with the nitrogen atom to which they are attached form a heterocyclic ring, optionally containing 1 to 4 lower alkyl substituents attached to carbon atoms of the heterocyclic ring, selected from morpholino, thiamorpholino, 1-pyrrolidinyl and 1-piperidino. Preferred compounds are often those in which X in the above general formula is oxygen.

The radical R.sup.3 may have a straight or branched chain and may contain, for example, up to 10 carbon atoms. Thus R.sup.3 may be, for example, hydrogen, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec.butyl, tert.butyl, n-pentyl, isopentyl, n-hexyl, n-heptyl, 1,1-diethylpropyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, allyl, 1-propenyl, 3-butenyl. Most suitably R.sup.3 is hydrogen, or lower alkyl such as propyl, isopropyl, n-butyl, sec.butyl, isobutyl, tert.butyl and especially methyl and ethyl.

R.sup.3 can also be optionally substituted alkylthio, alkenylthio, aralkylthio, alkoxyalkyl or alkylthioalkyl. An optionally substituted alkylthio radical can be branched or unbranched, and preferably contains 1 to 6 carbon atoms, especially 1 to 4 carbon atoms and the most preferred radicals are methylthio and ethylthio. The alkylthio group can be substituted with one or more substituent such as one or more halo atoms, an alkoxy group, an alkoxycarbonyl group, an alkylthio group, an alkenyloxy group or a dialkylamino group. Examples of these substituents include chloro, bromo, fluoro, methoxy, ethoxy, methoxycarbonyl, ethoxycarbonyl, methylthio, ethylthio, vinyloxy, dimethylamino and diethylamino.

When R.sup.3 is an optionally substituted alkenylthio radical it can, for instance, contain from 2 to 6 carbon atoms, preferably from 2 to 4 carbon atoms. When the radical is substituted preferred substituents are one or more halogen atoms, such as one or two halogen atoms, for example, bromo, fluoro and especially chloro.

When R.sup.3 is an optionally substituted aralkylthio radical it can be, for example, 2-phenylethylthio and is preferably benzylthio or benzylthio substituted with one or more substituent such as, for example, alkyl especially methyl, nitro, alkoxy especially methoxy, trifluoromethyl or halo, especially chloro. There are most suitably one or two substituents on the phenyl ring.

When R.sup.3 is an optionally substituted alkoxyalkyl or alkylthioalkyl radical it preferably contains 2 to 5, for example 2 to 4, carbon atoms.

Examples of such radicals are methylthio, ethylthio, propylthio, isopropylthio, n-butylthio, sec.butylthio, n-pentylthio, isopentylthio, hexylthio, methoxymethylthio, ethoxycarbonylmethylthio, methylthiomethylthio, vinyloxyethylthio, dimethylaminoethylthio, allylthio, 2-methylallylthio, 2-chloroprop-2-enylthio, but-2-enylthio, benzylthio, 4-chlorobenzylthio, 2,4-dichlorobenzylthio, 2-methylbenzylthio, 2,4-dimethylbenzylthio, 2-methyl-4-chloro-benzylthio, 3-trifluoromethylbenzylthio, 3-nitrobenzylthio, 2-methoxybenzylthio, 4-methoxybenzylthio, methoxymethyl, 2-methoxyethyl, 2-ethoxyethyl, 3-methoxypropyl or methylthiomethyl.

The radical R.sup.4 is alkyl or cycloalkyl and may contain, for example, up to 10 carbon atoms. Thus when R.sup.4 is alkyl it may have a straight or branched chain, may be a primary, secondary or tertiary radical, for example, methyl, ethyl, propyl, isopropyl, n-butyl isobutyl, sec.butyl, tert.butyl, 1-methylbutyl, 1-ethylpropyl, n-pentyl, isopentyl, tert.pentyl, n-hexyl, 1,1,2-trimethylpropyl, n-heptyl, 1,1-diethylpropyl, 2,3,3-trimethylbut-2yl, n-octyl, 2-ethylhexyl, n-nonyl or n-decyl. Preferred values of R.sup.4 when it is an alkyl group, are tert.butyl, sec.butyl, propyl, 1-ethylpropyl, isopropyl and tert.pentyl. When R.sup.4 is cycloalkyl it may contain, for example, up to 8, and more preferably from 3-7, carbon atoms in the cyclo ring. The cycloalkyl group may optionally contain one or more substituents on the ring, for example, one or more lower alkyl (especially methyl) substituents. A lower alkyl substituent is preferably in the 1-position, that is, it is attached to the cycloalkyl carbon atom joined to the imidazole ring. A further preferred group contains a lower alkyl (especially methyl) substituent in the 1-position and in addition one or more lower alkyl (especially methyl) substituents in other positions on the ring. When there is more than one substituent on the cycloalkyl group they may be the same or different. Thus, for example, typical values for R.sup.4 are cyclopropyl, 1-methylcyclopropyl, 2-methylcyclopropyl, 2,2-dimethylcyclopropyl, cyclobutyl, 1-methylcyclobutyl, cyclopentyl, 1-methylcyclopentyl, 1-ethylcyclopentyl, 2- 3- or 4-methylcyclopentyl, cyclohexyl, 1-methylcyclohexyl, 1-methylcyclohexyl containing 1, 2 or 3 further methyl substituents such as for example 1,3-dimethylcyclohexyl, 1,4-dimethylcyclohexyl, 1,3,3-trimethylcyclohexyl; 1-ethylcyclohexyl, 2- 3- or 4-methylcyclohexyl, 2,4-dimethylcyclohexyl, 2- 3- or 4-ethylcyclohexyl, cycloheptyl or cyclooctyl. Preferably, when R.sup.4 is cycloalkyl, it contains five or six carbon atoms in the cyclo ring and is cyclopentyl optionally containing one or more methyl substituents or cyclohexyl optionally containing one or more methyl substituents. Specific examples include cyclopentyl, 1-methylcyclopentyl, cyclohexyl, 1-methylcyclohexyl, 1,3-dimethylcyclohexyl, 1,3,3-trimethylcyclohexyl.

When the group NR.sup.1 R.sup.2 is an acyclic group both R.sup.1 and R.sup.2 may have a straight or branched chain. Preferably (a) R.sup.1 and R.sup.2 are the same or different and are lower alkyl or lower alkenyl; examples of lower alkyl are methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec.butyl, tert.butyl, n-pentyl, isopentyl, n-hexyl or n-heptyl; lower alkenyl may contain, for example, 2 to 4 carbon atoms, especially allyl; or (b) R.sup.1 is lower alkyl and R.sup.2 is alkoxyalkyl, containing for example from 3 to 6 carbon atoms such as for example 2-methoxyethyl, 2-ethoxyethyl or 3-ethoxypropyl, or lower haloalkyl containing for example from 1 to 6 carbon atoms and substituted by one or more halogen atoms preferably fluorine, chlorine or bromine, such as for example, 2-chloroethyl. It is preferred that either (a) R.sup.1 is methyl and R.sup.2 is lower alkyl or (b) R.sup.1 and R.sup.2 are both ethyl or propyl. A specially preferred group of compounds is that in which R.sup.1 is methyl and R.sup.2 is lower alkyl, preferably containing 1-4 carbon atoms and especially methyl.

As hereinbefore mentioned, when the group NR.sup.1 R.sup.2 is a heterocyclic group, it may contain 1-4 lower alkyl (especially methyl) substituents attached to carbon atoms of the heterocyclic ring. Such alkyl-substituted heterocyclic groups include, for example, 2,6-dimethylmorpholino, 4-methyl-1-piperidino, 2-methyl-1-piperidino, 2-6-dimethyl-1-piperidino and 2-ethyl-1-piperidino. When NR.sup.1 R.sup.2 is heterocyclic it is preferably morpholino, 1-pyrrolidinyl or 1-piperidino and especially morpholino. Compounds in which the group NR.sup.1 R.sup.2 is morpholino have the added advantage of low mammalian toxicity.

In utilising their pesticidal properties the compounds of the invention are preferably used as the free base but may also be employed as an acid addition salt which can be formed with an inorganic or organic acid, for example hydrochloric, hydrobromic, hydroiodic, hydrofluoric, sulphuric, nitric, phosphoric, perchloric, sulphamic, formic, acetic, trichloroacetic, oxalic, picric, benzenesulphonic, dodecylbenzenesulphonic, p-toluenesulphonic, stearic, flavianic, embonic or tetraiodophthalaic acids. Such salts are pesticidally active by virtue of the imidazole cation content of the salt.

We have found that the compounds of the present invention have pesticidal activity and, for example, can be used to combat insects. The compounds have activity against Diptera such as the larvae of the sheep blow fly, Lucilia sericata and species of Hemiptera. For example they are of use against California red scale, Acridiella aurantii, the Comstock, mealybug, Pseudococcus comstocki and plant hoppers such as, for example, the green rice leafhopper, Nephotettix cincticeps. They are especially useful in controlling aphids such as Aphis fabae, Megoura viciae, Myzus persicae, Phorodon humuli, Eriosoma lanigerum, Brevicoryne brassicae and Acyrthosiphon pisum. The compounds also have acaricidal activity against adults of the two-spotted mite, Tetranychus urticae and the citrus red mite, Panonychus citri.

According to a further feature of the present invention there are provided pesticidal, in particular insecticidal such as for example aphicidal, compositions which comprise as an active ingredient a compound of the present invention together with a diluent or carrier. The diluent or carrier may be a solid or a liquid, optionally in association with a surface-active agent, for example, a dispersing agent, emulsifying agent or wetting agent.

The compositions of the present invention may take any of the forms known in the art for the formulation of pesticidal or insecticidal compounds, for example solutions, aqueous dispersions, aqueous emulsions, dusting powders, dispersible powders, fumigants, emulsifiable concentrates and granules. Such compositions include not only compositions in a suitable form for application but also concentrated primary compositions which require dilution with a suitable quantity of water or other diluent before application. Dispersible powders and emulsifiable concentrates are typical examples of such primary compositions.

As dispersions, the compositions comprise essentially a compound of the invention dispersed in an aqueous medium. It is convenient to supply the consumer with a primary composition which may be diluted with water to form a dispersion having the desired concentration; the primary composition may be in any one of the following forms. It may be provided as a dispersible solution which comprises a compound of the invention dissolved in a water-miscible solvent with the addition of a dispersing agent. Alternatively it may be provided as a dispersible powder which comprises a compound of the invention and a dispersing agent. A further alternative comprises a compound of the invention in the form of a finely ground powder in association with a dispersing agent and intimately mixed with water to give a paste or cream. This paste or cream may if desired be added to an emulsion of oil in water to give a dispersion of active ingredient in an aqueous oil emulsion.

Emulsions comprise essentially a compound of the invention dissolved in a water-immiscible solvent which is formed into an emulsion with water in the presence of an emulsifying agent. An emulsion of the desired concentration may be formed from a primary composition of the following types. A concentrated stock emulsion may be supplied comprising a compound of the invention in combination with an emulsifying agent, water and a water-immiscible solvent. Alternatively there may be supplied an emulsifiable concentrate comprising a solution of a compound of the invention in a water-immiscible solvent containing an emulsifying agent.

A dusting powder comprises a compound of the invention intimately mixed and ground with a solid pulverulent diluent, for example kaolin.

A granular solid may comprise a compound of the invention associated with similar diluents to those which may be employed in dusting powders, but the mixture is granulated by known methods. Alternatively they may comprise the active ingredient absorbed or adsorbed on a pre-formed granular diluent for example fullers earth, attapulgite and limestone grit.

The concentration of the active ingredient in the primary compositions of the present invention may vary widely and may be, for example, 5 - 95% w/w of the composition. The concentration of the active ingredient in the compositions of the present invention for application to control pests, especially insects such as aphids, is generally within the range 0.001 - 10% w/w, especially 0.005 - 5% w/w.

According to a further feature of the present invention there is provided a method for combating pests, especially insects, which comprises applying a compound of the present invention to the locus of the pests, i.e. the pests or their habitat. A particular embodiment of this feature is a method for protecting plants from insects, and in particular aphids, which comprises applying a compound of the present invention to the locus of the plants, i.e. the plants or their habitat.

In combating pests the active compound can be applied on its own or preferably as one of the compositions described above. Direct treatment is often the preferred method, by for example, spraying, dusting or fumigation of plants infested with insects. Alternatively the active compound can be applied to the soil in which plants are grown as granules or as a root drench. In such instances the active compound is absorbed by the roots of the plant and confers protection from the insects. A suitable application rate of the compound of the present invention is generally within the range 0.005 - 10 lb/acre, more usually 0.01 - 5 lb/acre. The compounds of the present invention may be used to protect a variety of plants from aphids, for example ornamental plants such as roses, and crop plants such as fruit trees, leguminous crops, potatoes, hops, sugar beet, cotton, maize, rice and tobacco.

A composition of the invention may comprise as active ingredient more than one compound of the general formula I and it may also comprise one or more additional pesticide or, for example, a fungicide or insecticide for example an organochlorine or organophosphorus insecticide.

The compounds of the present invention may be prepared by a process which comprises reacting an imidazole of the general formula ##STR3## in which R.sup.3 and R.sup.4 are as hereinbefore defined with a carbamoyl halide or thiocarbamoyl halide of the general formula Z-CXNR.sup.1 R.sup.2 (III) in which R.sup.1, R.sup.2 and X are as hereinbefore defined and Z is halogen, for example, chlorine or bromine preferably chlorine. The reaction is suitably effected in the presence of an inert organic liquid as the reaction medium, which is preferably a solvent for the reactants. Advantageously the reaction is effected in the presence of a suitable acid-binding agent, for example a tertiary amine such as triethylamine or pyridine, in order to absorb the hydrogen halide produced in the reaction. In preparing the compounds by this route the reactants are preferably reacted together at a temperature of from 0.degree. to 120.degree. C., for example from 50.degree. to 95.degree. C. The salts of the invention can readily be prepared by treatment of the product with acid by well known methods.

The imidazole compounds of formula II in which R.sup.3 is optionally substituted alkylthio, alkenylthio, aralkylthio, alkoxyalkyl or alkylthioalkyl and R.sup.4 is cycloalkyl or alkyl containing more than one carbon atom are novel compounds.

Compounds of formula II in which R.sup.3 is optionally substituted alkylthio, alkenylthio or aralkylthio can be prepared by, for example, reacting an alkali metal thiocyanate with an appropriate aminomethyl ketone of the general formula

to give a thiol of the following formula ##STR4## which in its turn, can be alkylated, alkenylated or aralkylated according to well known methods to give compounds of formula II. Alternatively, compounds of formula II in which R.sup.3 is optionally substituted alkylthio, alkenylthio or aralkylthio can be prepared by reacting, in the presence of alkali, an .alpha.-haloketone of the general formula R.sup.4 COCH.sub.2 Z in which Z is halogen atom with an S-alkylisothiouronium salt of the following formula ##STR5## in which R.sup.3 is as defined immediately above and A represents a suitable anion, for example sulphate or halide.

Those compounds of formula II in which R.sup.3 is optionally substituted alkoxyalkyl or alkylthioalkyl can be made by, for example, condensing an aldehyde of the general formula R.sup.3 CHO in which R.sup.3 is optionally substituted alkoxyalkyl or alkylthioalkyl with an acyloxylated ketone of the general formula R.sup.4 COCH.sub.2 B in which B is acyloxy, in the presence of ammonia.

The carbamoyl halides or thiocarbamoyl halides of the general formula III may be prepared by reacting a secondary amine of the general formula HNR.sup.1 R.sup.2 with a carbonyl halide or thiocarbonyl halide of the general formula CXZ.sub.2 in which Z is preferably chlorine, in accordance with known methods.

The compounds of the present invention may also be prepared by a process which comprises reacting a carbamoyl halide or thiocarbamoyl halide of the general formula ##STR6## in which R.sup.3, R.sup.4 and Z are as hereinbefore defined, Z being halogen preferably chlorine, with a secondary amine of the general formula HNR.sup.1 R.sup.2, R.sup.1 and R.sup.2 being defined hereinbefore. The reaction is suitably effected in the presence of an inert organic liquid as the reaction medium, which is preferably a solvent for the reactants, at a temperature of from -5 to 50.degree. C. Advantageously the reaction is effected in the presence of a suitable acid-binding agent, for example a tertiary amine such as triethylamine or pyridine.

The compounds of the general formula V are preferably prepared in situ from the imidazoles of general formula II by reaction with a carbonyl halide or thiocarbonylhalide CXZ.sub.2, in which Z is preferably chlorine, suitably in the presence of a solvent and acid-binding agent; the secondary amine reactant then being added to the reaction product.

The compounds of the present invention may also be prepared by a process which comprises reacting a carbonylbisimidazole or thiocarbonylbisimidazole of the general formula ##STR7## in which R.sup.3, R.sup.4 and X are as hereinbefore defined, with a secondary amine of the general formula HNR.sup.1 R.sup.2, R.sup.1 and R.sup.2 being defined hereinbefore. The reaction is suitably effected in the presence of an inert organic liquid as the reaction medium, which is preferably a solvent for the reactants, at a temperature of, for example, from -5.degree. to 50.degree. C.

The compounds of the general formula VI are preferably prepared in situ by reacting an imidazole of the general formula II with about 0.5 molecular proportions of a carbonyl halide or thiocarbonyl halide CXZ.sub.2, in which Z is preferably chlorine; the secondary amine then being added to this reaction product. The reaction is preferably effected in the presence of a suitable acid-binding agent, for example a tertiary amine such as triethylamine or pyridine.

It will be appreciated that the reactions described above may give either or both of two isomeric products, depending on which nitrogen atom in the imidazole ring is substitued (the free hydrogen of the imidazole molecule of formula II can be associated with either of the ring nitrogen atoms). The products of the present invention may be conveniently designated as 1-(N,N-disubstituted-carbamoyl or thiocarbamoyl)-2-R.sup.3 -4(5)-R.sup.4 -imidazoles. This designation corresponds to formula I which encompasses both of the isomeric forms. The current state of our knowledge indicates that the solid products of the reactions described above, after purification by conventional techniques such as crystallization, are obtained in many instances as substantially pure 4-substituted compounds. The current state of our knowledge also indicates that the liquid products of the reactions described above, after isolation by conventional techniques such as distillation in vacuo, are obtained in many instances substantially or predominatly in the 4-substituted isomeric form. It will be appreciated that such isomers may be designated as 1-(N,N-disubstituted-carbamoyl)-2-R.sup.3 -4-R.sup.4 -imidazoles.

The following examples illustrate the invention.

To a stirred mixture of 173 g. 4-tert.butylimidazole, 205 ml. triethylamine and 300 ml. dry tetrahydrofuran was gradually added 167 g. dimethylcarbamoyl chloride. An exothermic reaction ensued, and the rate of addition of dimethylcarbamoyl chloride was adjusted so as to maintain a gentle boiling of the reaction mixture under reflux. When addition of the dimethylcarbamoyl chloride was complete, the reaction mixture was boiled under reflux with stirring for 1 hour, and then cooled to room temperature. The reaction mixture was diluted with 200 ml. water and then extracted with diethyl ether (2 .times. 200 ml.). The ethereal extracts were combined, dried over anhydrous sodium sulphate and evaporated. The resulting residue was crystallized from light petroleum (b.p. 100.degree. - 120.degree. C.) and recrystallized from di-isopropyl ether to give 1-dimethylcarbamoyl-4(5)-tert.butylimidazole, m.p. 85.degree. - 86.degree. C. The current state of our knowledge indicates that this compound is 1-dimethylcarbamoyl-4-tert.butylimidazole.

In an analogous manner to that described in Example 1, there was prepared 1-dimethylcarbamoyl-4(5)-methylimidazole, m.p. 58.degree. - 60.degree. C. (crystallized from light petroleum b.p. 100.degree. - 120.degree. C. and recrystallized from methylcyclohexane). The current state of our knowledge indicates that this compound is 1-dimethylcarbamoyl-4-methylimidazole.

A solution of 2.46 g. 4-tert.butylimidazole, 1.0 g. triethylamine and 2.42 g. N-ethyl-N-methylcarbamoyl chloride in 20 ml. dry tetrahydrofuran was boiled under reflux for 6.5 hours. The reaction mixture was cooled to room temperature and filtered to remove triethylamine hydrochloride. Solvent was removed from the resulting filtrate by evaporation under reduced pressure and the residue was distilled under reduced pressure to give 1-(N-methyl-N-ethylcarbamoyl)-4(5)-tert.butylimidazole, b.p. 99.degree. - 101.degree. C./0.1 mm.

In an analogous manner to that described above, there were prepared the following compounds:

1-dimethylthiocarbamoyl-4(5)-tert.butylimidazole, b.p. 140.degree. - 141.degree. C./1.0 mm.

1-(N-methyl-N-propylcarbamoyl)-4(5)-tert.butylimidazole, b.p. 120.degree. - 122.degree. C./0.5 mm.

1-(N-methyl-N-heptylcarbamoyl)-4(5)-tert.butylimidazole, b.p. 154.degree. - 156.degree. C./0.7 mm.

1-diallylcarbamoyl-4(5)-tert.butylimidazole, b.p. 120.degree. - 121.degree. C./0.2 mm.

1-(N-methyl-N-allylcarbamoyl)-4(5)-tert.butylimidazole, b.p. 126.degree. - 128.degree. C./1.0 mm.

1-dimethylcarbamoyl-2-ethyl-4(5)-methylimidazole, b.p. 85.degree. C./0.15 mm.

1-dimethylcarbamoyl-4(5)-n-pentylimidazole, b.p. 120.degree. C./0.09 mm.

1-dimethylcarbamoyl-4(5)-isobutylimidazole, b.p. 104.degree. C./0.13 mm.

1-dimethylcarbamoyl-4(5)-isopropylimidazole, b.p. 98.degree. C./0.13 mm.

1-dipropylcarbamoyl-4(5)-isobutylimidazole, b.p. 104.degree. - 106.degree. C./0.05 mm.

1-dipropylcarbamoyl-4(5)-isopropylimidazole, b.p. 108.degree. C./0.12 mm.

1-dimethylthiocarbamoyl-4(5)-isopropylimidazole, b.p. 107.degree. - 114.degree. C./0.03 - 0.05 mm.

1-dimethylcarbamoyl-4(5)-(1-ethylpropyl)imidazole, b.p. 112.degree. C./0.15 mm.

1-dipropylcarbamoyl-4(5)-(1-ethylpropyl)imidazole, b.p. 100.degree. - 106.degree. C./0.25 - 0.03 mm.

1-dimethylcarbamoyl-2-methyl-4(5)-methylimidazole, b.p. 80.degree. - 84.degree. C./0.7 - 0.1 mm.

1-dimethylcarbamoyl-4(5)-isopropylimidazole, b.p. 98.degree. C./0.13 mm.

1-dimethylthiocarbamoyl-2-ethyl-4(5)-methylimidazole, b.p. 128.degree. - 130.degree. C./0.3 mm.

1-dimethylcarbamoyl-4(5)-sec.butylimidazole, b.p. 95.degree. C./0.04 mm.

1-(2,6-dimethylmorpholinocarbonyl)-4(5)-tert.butylimidazole, b.p. 154.degree. C./1.0 mm.

The current state of our knowledge indicates that the 4(5) alkyl groups of the imidazoles listed above are predominantly or substantially in the 4-position.

A mixture of 5.52 g. 4-tert.butylimidazole, 6.1 g. triethylamine, 8.95 g. morpholinocarbonyl chloride and 30 ml. dry tetrahydrofuran was boiled under reflux for 5 hours. The reaction mixture was diluted with 100 ml. methylene dichloride, cooled to room temperature, and washed with water to remove triethylamine hydrochloride. The resulting organic solution was dried over anhydrous magnesium sulphate and then evaporated to dryness. The resulting solid residue was recrystallized from ethanol to give 1-morpholinocarbonyl-4(5)-tert.butylimidazole, m.p. 129.degree. - 130.degree. C. The current state of our knowledge indicates that this compound is 1-morpholinocarbonyl-4-tert.butylimidazole.

A mixture of 5.0 g. 4-tert.butylimidazole, 4.4 g. triethylamine, 5.9 g. 1-piperidinocarbonyl chloride and 30 ml. dry tetrahydrofuran was boiled under reflux for 5.5 hours. The reaction mixture was cooled, filtered to remove triethylamine hydrochloride, and evaporated to dryness. The resulting solid residue was recrystallized from petroleum (b.p. 62.degree. - 68.degree. C.) to give 1-piperidinocarbonyl-4(5)-tert.butylimidazole, m.p. 104.degree. - 105.degree. C.

The following compound was prepared in an analogous manner.

1-(1-pyrrolidinylcarbonyl)-4(5)-tert.butylimidazole, m.p. 124.degree. - 126.degree. C.

The current state of our knowledge indicates that the tert.butyl group in the above compounds is in the 4-position.

In an analogous manner to that described in Example 3, the following compounds were prepared:

1-dimethylcarbamoyl-4(5)-sec.butylimidazole, b.p. 114.degree.-122.degree. C./0.1 mm.

1-(N-methyl-N-2-ethoxyethylcarbamoyl)-4(5)-tert.butylimidazole, b.p. 137.degree. - 138.degree. C./0.4 mm.

1-dimethylcarbamoyl-4(5)-propylimidazole, b.p. 108.degree. C./0.27 mm.

1-dimethylcarbamoyl-4(5)-butylimidazole, b.p. 109.degree. C./0.1 mm.

1-morpholinocarbonyl-4(5)-sec.butylimidazole, b.p. 119.degree. - 126.degree. C./0.05 mm.

1-morpholinocarbonyl-4(5)-isobutylimidazole, b.p. 136.degree. - 138.degree. C./0.15 mm.

1-morpholinocarbonyl-4(5)-butylimidazole, b.p. 126.degree. - 127.degree. C./0.02 mm.

1-(N-methyl-N-butylcarbamoyl)-4(5)-tert.butylimidazole, b.p. 152.degree. - 154.degree. C./2.0 mm.

1-(N-methyl-N-pentylcarbamoyl)-4(5)-tert.butylimidazole, b.p. 160.degree. - 162.degree. C./2.0 mm.

1-(N-methyl-N-hexylcarbamoyl)-4(5)-tert.butylimidazole, b.p. 170.degree. - 172.degree. C./2.0 mm.

1-piperidinocarbonyl-4(5)-isopropylimidazole, b.p. 170.degree. - 175.degree. C./3.0 mm.

1-piperidinocarbonyl-4(5)-sec.butylimidazole, b.p. 190.degree. C./8 mm.

1-pyrrolidinylcarbonyl-4(5)-sec.butylimidazole, b.p. 208.degree. C./22 mm.

1-diethylcarbamoyl-4(5)-sec.butylimidazole, b.p. 165.degree. C./6 mm.

1-(N-methyl-N-ethylcarbamoyl)-4(5)-isopropylimidazole, b.p. 160.degree. - 164.degree. C./9.0 mm.

1-morpholinocarbonyl-4(5)-isopropylimidazole, b.p. 180.degree. - 185.degree. C./5.0 mm.

1-dimethylthiocarbamoyl-4(5)-(1-methylbutyl)imidazole b.p. 180.degree. - 185.degree. C./5.5 mm.

1-dimethylthiocarbamoyl-4(5)-(1-methylbutyl)imidazole b.p. 165.degree. - 170.degree. C./4 mm.

1-(N-methyl-N-ethylcarbamoyl)-4(5)-sec.butylimidazole, b.p. 178.degree. C./28 mm.

1-(N-methyl-N-ethylthiocarbamoyl)-4(5)-sec.butylimidazole b.p. 182.degree. C./7 mm.

1-dimethylcarbamoyl-4(5)-(1,2-dimethylbutyl)imidazole, b.p. 125.degree. C./0.15 mm.

1-dimethylcarbamoyl-4(5)-(1-methylheptyl)imidazole, b.p. 125.degree. C./0.02 mm.

1-dimethylcarbamoyl-4(5)-(1-methylpentyl)imidazole, b.p. 128.degree. C./0.5 mm.

1-morpholinocarbonyl-4(5)-isopropylimidazole, b.p. 124.degree. C./0.14 mm.

1-dimethylthiocarbamoyl-4(5)-tert.pentylimidazole, b.p. 180.degree. - 185.degree. C./6.0 mm.

1-(N-methyl-N-2-methoxyethylcarbamoyl)-4(5)-tert.butylimidazole, b.p. 116.degree. - 118.degree. C./0.2 mm.

1-(N-methyl-N-3-ethoxypropylcarbamoyl)-4(5)-tert.butylimidazole, b.p. 132.degree. - 134.degree. C./0.3 mm.

1-(N-methyl-N-3-ethoxypropylcarbamoyl)-4(5)-sec.butylimidazole, b.p. 131.degree. - 132.degree. C./0.15 mm.

1-(N-methyl-N-2-ethoxyethylcarbamoyl)-4(5)-sec.butylimidazole, b.p. 140.degree. - 144.degree. C./0.4 mm.

1-dimethylcarbamoyl-4(5)-(1-methylnonyl)imidazole, b.p. 135.degree. C./0.04 mm.

1-dimethylcarbamoyl-4(5)-(1-butylpentyl)imidazole, b.p. 135.degree. C./0.05 mm.

1-dimethylcarbamoyl-4(5)-(1-ethylpentyl)imidazole, b.p. 125.degree. - 130.degree. C./0.2 mm.

1-(N-methyl-N-ethylthiocarbamoyl)-4(5)-tert.butylimidazole, b.p. 118.degree. - 121.degree. C./0.2 mm.

1-(N-methyl-N-3-methoxypropylcarbamoyl)-4(5)-tert.butylimidazole, b.p. 116.degree. - 122.degree. C./0.2 mm.

The current state of our knowledge indicates that the above compounds were obtained predominantly or substantially as the 4-substituted compounds.

To a stirred solution of 14 g. 4-tert.pentylimidazole in 100 ml. dry tetrahydrofuran and 28 ml. triethylamine was gradually added 13 g. dimethylcarbamoyl chloride. When addition of the carbamoyl chloride was complete the reaction mixture was boiled under reflux with stirring for one hour, then cooled to room temperature and poured on to 500 g. water and crushed ice. After extraction with ether, the ether layer was separated, washed with water and dried over anhydrous magnesium sulphate. The ether was evaporated and a residue remained which was crystallized from petroleum ether (b.p. 60.degree. - 80.degree. C.) to give the product, 1-dimethylcarbamoyl-4(5)-tert.pentylimidazole, m.p. 60.degree. - 61.degree. C. The current state of our knowledge indicates that this compound is 1-dimethylcarbamoyl-4-tert.pentylimidazole.

The 4-tert.pentylimidazole used in the above reaction was prepared in the following way:

A solution of 121.5 g. bromine 150 ml. chloroform was added dropwise with stirring to a solution of 87 g. 3,3-dimethylpentan-2-one in 360 ml. methanol. The reaction was initiated by the addition of a few drops of bromine solution at 15.degree. C., then cooled to 0.degree. C. and addition of bromine continued whilst the temperature was maintained at 0.degree. - 5.degree. C. After completion of the bromine addition the reaction mixture was stirred at 0.degree. - 5.degree. C. for ten minutes, then poured on to a mixture of crushed ice and water. The water layer was extracted with methylene dichloride and the extract added to the organic portion. The combined liquors were washed with water, saturated solution of sodium bicarbonate and then dried over calcium chloride. After evaporating the solvent under reduced pressure, 1-bromo-3,3-dimethylpentan-2-one distilled over, b.p. 84.degree. C./9 mm.

A mixture of 111.5 g. 1-bromo-3,3-dimethylpentan-2-one and 300 ml. formamide was heated with stirring. A weak stream of ammonia was passed through the reaction mixture over a period of one hour, the temperature being maintained at from 140.degree. - 160.degree. C. The stream of ammonia was then stopped and the reaction mixture maintained at a temperature of 160.degree. C. for 2 hours. Excess of formamide was evaporated under reduced pressure, the residue diluted with a little warm water and basified with potassium carbonate. The imidazole was separated with ether, the ethereal extract being washed with water and dried over anhydrous sodium sulphate.

After evaporating the solvent under reduced pressure, the residue was distilled to give the product, 4-tert.pentylimidazole, b.p. 114.degree. - 116.degree. C./0.2 mm. On standing this liquid solidified and the solid crystallized from petroleum ether (b.p. 60.degree. - 80.degree. C.) to give a pure product having a melting point of 95.degree. - 96.degree. C.

In an analogous way to that described above, the following compounds were prepared:

1-dimethylcarbamoyl-4(5)-neopentylimidazole, m.p. 63.degree. - 66.degree. C.

1-dimethylcarbamoyl-4(5)-(2,3,3-trimethyl-but-2'-yl)imidazole, m.p. 70.degree. - 71.degree. C.

1-morpholinocarbonyl-4(5)-tert.pentylimidazole, m.p. 98.degree. - 99.degree. C.

1-pyrrolidinylcarbonyl-4(5)-tert.pentylimidazole, m.p. 109.degree. - 110.degree. C.

1-dimethylcarbamoyl-4(5)-(1,1,2-trimethylpropyl)imidazole, m.p. 85.degree. - 86.degree. C.

1-(n-ethyl-N-methylcarbamoyl)-4(5)-tert.pentylimidazole, m.p. 38.degree. - 40.degree. C.

1-morpholinocarbonyl-4(5)-(2,3,3-trimethylbut-2'-yl)imidazole, m.p. 122.degree. - 123.degree. C.

1-(4-methylpiperidinocarbonyl)-4(5)-tert.butylimidazole, m.p. 87.degree. C.

1-(n-methyl-N-isopropylcarbamoyl)-4(5)-tert.butylimidazole, m.p. 72.degree. - 73.degree. C.

1-(n-methyl-N-2-chloroethylcarbamoyl)-4(5)-tert.butylimidazole, m.p. 84.degree. - 85.degree. C.

1-pyrrolidinylcarbonyl-4(5)-isopropylimidazole, m.p. 70.degree. - 71.degree. C.

The current state of our knowledge indicates that the above imidazoles were obtained predominantly or substantially as the 4-substituted compounds.

In the course of preparing the above compounds the following novel intermediates were made.

4-(2,3,3-trimethyl-but-2-yl)imidazole, m.p. 149.degree. - 150.degree. C.

4-(1,1,2-trimethylpropyl)imidazole, b.p. 110.degree. - 114.degree. C./0.1 mm.

4-neopentylimidazole, b.p. 106.degree. - 114.degree. C./0.15 - 0.19 mm.

To a stirred solution of 1.25 g. 2-methyl-4-tert.butylimidazole in 10 ml. tetrahydrofuran and 2 ml. triethylamine was added 1.2 g. dimethylcarbamoyl chloride. The resulting mixture was boiled under reflux with stirring for 31/2 hours and then cooled to room temperature. The reaction mixture was diluted with 100 ml. methylene chloride, washed with water, and the methylene chloride solution dried over magnesium sulphate. After evaporating the solvent the residue was distilled under reduced pressure to give 1-dimethylcarbamoyl-2-methyl-4(5)-tert.butylimidazole, b.p. 126.degree. - 127.degree. C./1 mm. This liquid solidified on standing and when recrystallized from petroleum ether (b.p. 60.degree. - 80.degree. C.) gave the pure product, m.p. 80.degree. - 81.degree. C. The current state of our knowledge indicates that this compound is 1-dimethylcarbamoyl-2-methyl-4-tert.butylimidazole.

The imidazole used in the above reaction was prepared in the following way:

85 g. Bromopinacolone was added to a solution of 72 g. potassium acetate in 700 ml. methanol and the resulting mixture was refluxed on a steam bath for two hours. It was then cooled, filtered and the filtrate added with stirring to a solution of 190 g. cupric acetate monohydrate in 800 ml. water and 1000 ml. 25 per cent ammonia. A solution of 26 g. acetaldehyde in 200 ml. water was then added to the mixture which was heated on a steam bath for 5 hours with constant stirring.

After cooling the cuprous salt of the imidazole was collected, washed with water and suspended in 500 ml. of 4N acetic acid. While stirring, a solution of 78 g. potassium ferricycanide in 240 ml. water was added and the precipitated copper complex removed and washed well with water. The combined supernatant liquors were basified to pH 9 - 10 with 5N sodium hydroxide and extracted several times with ether. The ethereal extracts were combined, washed with water and dried over anhydrous sodium sulphate. After evaporation of the solvent under reduced pressure the residue distilled to give the imidazole product, b.p. 112.degree. - 114.degree. C./0.05 mm. This solidified on standing and was recrystallized from a mixture of petroleum ether (60.degree. - 80.degree. C.) containing a few drops of ethanol to give 2-methyl-4-tert.butylimidazole, m.p. 155.degree. - 156.degree. C.

In an analogous way to that described above, the following compounds were prepared:

1-dimethylcarbamoyl-2-ethyl-4(5)-tert.butylimidazole, b.p. 108.degree. - 109.degree. C./0.7 mm.

1-morpholinocarbonyl-2-ethyl-4(5)-tert.butylimidazole, b.p. 124.degree. - 126.degree. C./0.15 mm.

1-dimethylcarbamoyl-2-isopropyl-4(5)-tert.butylimidazole, b.p. 86.degree. C./0.1 mm., m.p. 57.degree. - 58.degree. C.

1-dimethylcarbamoyl-2-butyl-4(5)-tert.butylimidazole, b.p. 108.degree. - 110.degree. C./0.2 mm.

1-morpholinocarbonyl-2-butyl-4(5)-tert.butylimidazole, b.p. 138.degree. - 141.degree. C./0.4 mm.

1-dimethylcarbamoyl-2-isobutyl-4(5)-tert.butylimidazole, b.p. 106.degree. - 108.degree. C./0.25 mm.

1-dimethylcarbamoyl-2-(1-methylbutyl)-4(5)-tert.butylimidazole, b.p. 98.degree. - 100.degree. C./0.15 mm.

1-dimethylcarbamoyl-2-sec.butyl-4(5)-tert.butylimidazole, b.p. 102.degree. - 104.degree. C./0.25 mm.

1-dimethylcarbamoyl-2-(2,6-dimethylhept-5-enyl)-4(5)-tert.butylimidazole, b.p. 154.degree. - 156.degree. C./0.4 mm.

1-dimethylcarbamoyl-2-(1-ethylpropyl)-4(5)-tert.butylimidazole, b.p. 97.degree. - 98.degree. C./0.15 mm.

1-(N-methyl-N-2-ethoxyethylcarbamoyl)-2-methyl-4(5)-tert.butylimidazole, b.p. 115.degree. - 117.degree. C./0.1 mm.

1-(N-methyl-N-propylcarbamoyl)-2-methyl-4(5)-tert.butylimidazole, b.p. 108.degree. - 110.degree. C./0.3 mm.

1-dimethylcarbamoyl-2-(1-ethyl-2-methylpropyl)-4(5)-tert.butylimidazole, b.p. 108.degree. - 110.degree. C./0.2 mm.

1-morpholinocarbonyl-2-methyl-4(5)-tert.butylimidazole, m.p. 113.degree. - 114.degree. C.

1-dimethylthiocarbamoyl-2-methyl-4(5)-tert.butylimidazole, m.p. 110.degree. - 112.degree. C.

1-pyrrolidinylcarbonyl-2-methyl-4(5)-tert.butylimidazole, butylimidazole, b.p. 119.degree. - 124.degree. C./0.1 mm.

1-dimethylcarbamoyl-2-propyl-4(5)-tert.butylimidazole, b.p. 102.degree. - 104.degree. C./0.3 mm.

1-(N-methyl-N-ethylcarbamoyl)-2-methyl-4(5)-tert.butylimidazole, b.p. 106.degree. - 108.degree. C./0.4 mm.

1-dimethylthiocarbamoyl-2-ethyl-4(5)-sec.butylimidazole, b.p. 120.degree. - 122.degree. C./0.1 mm.

1-dimethylcarbamoyl-2-propyl-4(5)-sec.butylimidazole, b.p. 108.degree. - 110.degree. C./0.15 mm.

1-dimethylcarbamoyl-2-ethyl-4(5)-sec.butylimidazole, b.p. 110.degree. - 112.degree. C./0.3 mm.

1-morpholinocarbonyl-2-methyl-4(5)-sec.butylimidazole, b.p. 142.degree. - 145.degree. C./0.1 mm.

1-dimethylthiocarbamoyl-2-methyl-4(5)-sec.butylimidazole, b.p. 130.degree. - 134.degree. C./0.3 mm.

1-dimethylcarbamoyl-2-methyl-4(5)-sec.butylimidazole, b.p. 118.degree. - 120.degree. C./0.2 mm.

1-morpholinocarbonyl-2-ethyl-4(5)-sec.butylimidazole, b.p. 134.degree. - 136.degree. C./0.1 mm.

1-dimethylcarbamoyl-2-methyl-4(5)-propylimidazole, b.p. 104.degree. - 107.degree. C./0.1 mm.

1-morpholinocarbonyl-2-methyl-4(5)-propylimidazole, b.p. 128.degree. - 130.degree. C./0.1 mm.

The current state of our knowledge indicates that the above imidazoles were obtained predominantly or substantially as the 4-substituted compounds.

In the course of preparing the above compounds the following novel intermediates were made:

2-ethyl-4-tert.butylimidazole, m.p. 154.degree. - 155.degree. C.

2-isopropyl-4-tert.butylimidazole, m.p. 182.degree. C.

2-butyl-4-tert.butylimidazole, m.p. 70.degree. - 72.degree. C.

2-isobutyl-4-tert.butylimidazole, m.p. 128.degree. - 129.degree. C.

2-(1-methylbutyl)-4-tert.butylimidazole, m.p. 108.degree. - 109.degree. C.

2-sec.butyl-4-tert.butylimidazole, m.p. 136.degree. C.

2-(1-ethylpropyl)-4-tert.butylimidazole, m.p. 145.degree. - 146.degree. C.

2-(1-ethyl-2-methylpropyl)-4-tert.butylimidazole, m.p. 148.degree. C.

2-propyl-4-tert.butylimidazole, m.p. 124.degree. - 125.degree. C.

2-ethyl-4-sec.butylimidazole, b.p. 120.degree. - 122.degree. C./0.25 mm.

2-propyl-4-sec.butylimidazole, b.p. 116.degree. - 118.degree. C./0.15 mm.

2-methyl-4-sec.butylimidazole, m.p. 63.degree. - 65.degree. C.

This example describes an alternative method of preparing 1-dimethylcarbamoyl-4(5)-tert.butylimidazole.

A solution of 6.2 g. tert.butylimidazole (0.05 mole) and 4 g. pyridine in 15 ml. dry tetrahydrofuran was added dropwise to a stirred solution of 2.5 g. phosgene (0.025 mole) in 25 ml. dry tetrahydrofuran maintained at a temperature of 0.degree. to 5.degree. C. The mixture was stirred for 1 hour and filtered. To the filtrate was gradually added a cold solution of 1.37 g. anhydrous dimethylamine (0.03 mole) in 15 ml. dry tetrahydrofuran at 0.degree. C. The mixture was stirred for two hours at 0.degree. to 5.degree. C., filtered and the solvent evaporated. The residue distilled under reduced pressure to give a fraction having b.p. 102.degree. C./0.5 mm. which solidified on cooling. After crystallization from petroleum ether (60.degree. - 80.degree. C.) the pure product, 1-dimethylcarbamoyl- 4(5)-tert.butylimidazole m.p. 85.degree. - 86.degree. C., was isolated. The current state of our knowledge indicates that this compound is 1-dimethylcarbamoyl-4-tert.butylimidazole.

This example describes an alternative method of preparing 1-dimethylcarbamoyl-4(5)-tert.butylimidazole.

A solution of 6.2 g. tert.butylimidazole (0.05 mole) and 16 g. pyridine in 15 ml. dry tetrahydrofuran was added dropwise to a stirred solution of 5 g. phosgene (0.05 mole) in 50 ml. dry tetrahydrofuran at a temperature of 0.degree. to 5.degree. C. The mixture was stirred for an hour and filtered. To the filtrate was gradually added a cold solution of 3 g. anhydrous dimethylamine (0.065 mole) in 30 ml. dry tetrahydrofuran at 0.degree. to 5.degree. C. The mixture was stirred for 2 hours at 0.degree. to 5.degree. C., filtered and the solvent evaporated. The residue distilled under reduced pressure to give a fraction having b.p. 102.degree. C./0.5 mm. which solidified on cooling. After crystallization from petroleum ether (60.degree. - 80.degree. C.) the pure product, 1-dimethylcarbamoyl-4(5)-tert.butylimidazole, m.p. 85.degree. - 86.degree. C., was isolated. The current state of our knowledge indicates that this compound is 1-dimethylcarbamoyl-4-tert.butylimidazole.

To a stirred solution of 62 g. 4-(1-methylcyclohexyl)-imidazole in 85 ml. dry tetrahydrofuran and 56 ml. triethylamine was gradually added 45 g. dimethylcarbamoyl chloride. An exothermic reaction ensued and the rate of addition of dimethylcarbamoyl chloride was adjusted so as to maintain a gentle boiling of the reaction mixture under reflux. When addition of the dimethylcarbamoyl chloride was complete, the reaction mixture was boiled under reflux with stirring for one hour, and then cooled to room temperature. The reaction mixture was diluted with 200 ml. water and then extracted with ether (2 .times. 200 ml.). The ethereal extracts were combined, washing with water and dried over anhydrous sodium sulphate. After evaporation the resulting residue was crystallized from light petroleum (b.p. 60.degree. - 80.degree. C.) to give the product, 1-dimethylcarbamoyl-4(5)-(1-methylcyclohexyl)imidazole, m.p. 72.degree. - 73.degree. C. The current state of our knowledge indicates that this compound is 1-dimethylcarbamoyl-4-(1-methylcyclohexyl)imidazole.

The 4-(1-methylcyclohexyl)imidazole used in the above reaction was prepared in the following way:

A solution of 328 g. bromine in 300 ml. chloroform was added gradually to a stirred solution of 300 g. 1-methylcyclohexyl methyl ketone in 100 ml. methanol. After the addition of a few drops of bromine solution at 15.degree. C. the reaction mixture was cooled and maintained between 0.degree. - 5.degree.C. The reaction mixture was stirred for 10 minutes, after the addition of bromine had been completed, and then poured on to a mixture of crushed ice and water. The water layer was separated from the organic liquid and extracted with methylene chloride. The extract and the organic portion were combined and washed with water followed by a saturated solution of sodium bicarbonate and then finally with water. After drying over calcium chloride the liquid was evaporated and distilled to give bromomethyl 1-methylcyclohexyl ketone, b.p. 76.degree. - 78.degree. C./0.1 mm. Hg.

A mixture of 387 g. bromomethyl 1-methylcyclohexyl ketone and 1000 ml. formamide was heated with stirring. A stream of ammonia was passed through the reaction mixture over a period of one hour, the mixture being maintained at a temperature of 140.degree. - 160.degree. C. After the passage of ammonia had been completed the reaction mixture was heated to 180.degree. - 190.degree. C. The reaction mixture was maintained at this temperature for a period of two hours. Excess of formamide was evaporated under reduced pressure and the residue diluted with a little warm water and made alkaline with potassium carbonate. The resulting mixture was extracted with ether. After separation the ethereal extract was washed with water, dried over sodium sulphate, evaporated and distilled to give the novel intermediate 4-(1-methylcyclohexyl)imidazole, b.p. 146.degree. - 148.degree. C./0.2 mm. Hg. The distillate crystallized from petroleum ether (b.p. 60.degree. - 80.degree. C.) to give the product, m.p. 73.degree. - 75.degree. C.

In an analogous manner to that described above, there were prepared the following compounds:

1-dimethylcarbamoyl-4(5)-cyclohexylimidazole, m.p. 107.degree. - 108.degree. C. (crystallized from petroleum ether, b.p. 100.degree. - 120.degree. C.)

1-dimethylcarbamoyl-4(5)-(1-methylcyclopentyl)imidazole, m.p. 73.degree. C. (crystallized from petroleum ether, b.p. 60.degree. - 80.degree. C.)

The current state of our knowledge indicates that the 4(5) cycloalkyl groups of the imidazoles listed above are predominantly or substantially in the 4-position.

In the course of preparing the above imidazoles, the following novel intermediate was made:

4-(1-methylcyclopentyl)imidazole, m.p. 33.degree. - 35.degree. C; b.p. 136.degree. - 140.degree. C./0.5 mm.

To a stirred solution of 9.6 g. of 4-(1-methylcyclohexyl) imidazole and 14 ml. triethylamine in 80 ml. tetrahydrofuran was gradually added 11.9 g. morpholinocarbonyl chloride. An exothermic reaction ensued and the rate of addition of dimethylcarbamoyl chloride was adjusted so as to maintain a gentle boiling of the reaction mixture under reflux. When addition of the morpholinocarbonyl chloride was complete, the reaction mixture was boiled under reflux with stirring for 5 hours, and then cooled to room temperature. The reaction mixture was diluted with 200 ml. water and then extracted with ether (2 .times. 200 ml.). The ethereal extracts were combined, washed with water and dried over anhydrous sodium sulphate. After evaporation the resulting residue was crystallized from petroleum ether (b.p. 80.degree. - 100.degree. C.) to give the product, 1-morpholinocarbonyl-4(5)-(1-methylcyclohexyl)imidazole, m.p. 127.degree. - 128.degree. C.

The 4-(1-methylcyclohexyl)imidazole used in the above reaction was prepared as in Example 11.

In an analogous manner to that described above, there was prepared the following compound:

1-morpholinocarbonyl-4(5)-(1-methylcyclopentyl)-imidazole, m.p. 82.degree. - 83.degree. C. (crystallized from petroleum ether, b.p. 60.degree. - 80.degree. C.)

The current state of our knowledge indicates that the 1-methylcycloalkyl groups of the above compounds are in the 4-position.

In an analogous way to that described in Example 11, there were prepared the following compounds:

1-piperidinocarbonyl-4(5)-(1-methylcyclohexyl)imidazole, m.p. 85.degree. - 87.degree. C.

1-pyrrolidinylcarbonyl-4(5)-(1-methylcyclohexyl)imidazole, m.p. 110.degree. - 111.degree. C.

1-pyrrolidinylcarbonyl-4(5)-(1-methylcyclopentyl)imidazole, m.p. 87.degree. - 89.degree. C.

1-piperidinocarbonyl-4(5)-(1-methylcyclopentyl)imidazole, m.p. 77.degree. - 79.degree. C.

1-dimethylcarbamoyl-4(5)-(1-methylcyclopentyl)imidazole, m.p. 64.degree. - 65.degree. C.

1-(n-ethyl-N-methylcarbamoyl)-4(5)-(1-methylcyclopentyl)imidazole, m.p. 47.degree. - 49.degree. C.

1-dimethylcarbamoyl-4(5)-(1-cyclohexyl-1-methylethyl)imidazole, m.p. 112.degree. C.

The current state of our knowledge indicates that the above compounds were obtained predominantly or substantially as the 4-substituted compounds.

A mixture of 20.1 g. 4-(1,3-dimethylcyclohexyl)imidazole, 150 ml. dry tetrahydrofuran, 28 ml. triethylamine and 16.2 g. dimethylcarbamoyl chloride were refluxed on a steam bath for an hour and then cooled. Methylene chloride was added and the solution washed with water, the first washing being re-extracted with methylene chloride. The methylene chloride extracts were dried over magnesium sulphate solution. After filtration the solution was evaporated to give the product, 1-dimethylcarbamoyl-4(5)-(1,3-dimethylcyclohexyl)imidazole, b.p. 138.degree. - 140.degree. C./0.08 mm. The current state of our knowledge indicates that this product is predominantly 1-dimethylcarbamoyl-4-(1,3-dimethylcyclohexyl)imidazole

The 4-(1,3-dimethylcyclohexyl)imidazole used in the above reaction was prepared in the following way:

A solution of 75 ml. (1.465 mole) bromine in 250 ml. chloroform was added dropwise to a stirred solution of 235 g. 1,3-dimethylcyclohexyl methyl ketone in 71 ml. methanol whilst maintaining the temperature of 0.degree. - 5.degree. C. (the reaction was started by addition of a few drops of bromine solution at 15.degree. C. then cooled to 0.degree. C. and continued). The reaction mixture was stirred at 0.degree. - 5.degree. C. for 10 minutes after the addition of bromine solution was complete, then poured on to crushed ice and water mixture. After extracting the water layer with methylene chloride, the methylene chloride was added to the organic portion and the mixture washed with water, saturated sodium bicarbonate solution and dried over calcium chloride. The solvent was evaporated and distillation gave bromomethyl-1,3-dimethylcyclohexyl ketone, b.p. 86.degree. - 89.degree. C./0.1 mm.

A mixture of 265 g. bromomethyl-1,3-dimethylcyclohexyl ketone and 645 ml. formamide was heated with stirring. A weak stream of ammonia was passed through at 140.degree. C. and the temperature raised from 140.degree. - 160.degree. C. for 1 hour. The stream of ammonia was then stopped and the reaction mixture heated to 180.degree. - 190.degree. C, for 2 hours. Excess formamide was evaporated under reduced pressure, the residue diluted with a little warm water and basified with potassium carbonate. The imidazole was separated with ether, washed with water and dried over sodium sulphate. After evaporation of the ether, the novel product was distilled over, 4-(1,3-dimethylcyclohexyl)imidazole, b.p. 140.degree. - 142.degree. C./0.15 mm.

In an analogous manner to that described above, there were prepared the following compounds:

1-diethylcarbamoyl-4(5)-(1-ethylcyclohexyl)imidazole, b.p. 140.degree. C./0.2 mm.

1-morpholinocarbonyl-4(5)-(1,3-dimethylcyclohexyl)imidazole, b.p. 160.degree. - 162.degree. C./0.02 mm.

1-dimethylthiocarbamoyl-4(5)-(1-methylcyclohexyl)imidazole, b.p. 210.degree. - 214.degree. C./3.0 mm.

1-diethylthiocarbamoyl-4(5)-(1-methylcyclohexyl)imidazole, b.p. 159.degree. - 164.degree. C./0.3 mm.

1-dimethylcarbamoyl-4(5)-(1,3,3-trimethylcyclohexyl)imidazole, b.p. 142.degree. - 144.degree. C./0.1 mm.

1-(N-methyl-N-2-butoxyethylcarbamoyl)-4(5)-(1-methylcyclohexyl)imidazole, b.p. 166.degree. - 175.degree. C./0.6 mm.

1-(N-methyl-N-2-ethoxyethylcarbamoyl)-4(5)-(1-methylcyclohexyl)imidazole, b.p. 210.degree. - 215.degree. C./4.5 mm.

1-(N-methyl-N-2-methoxyethylcarbamoyl)-4(5)-(1-methylcyclohexyl)imidazole, b.p. 146.degree. - 149.degree. C./0.2 mm.

1-(N-methyl-N-3-ethoxypropylcarbamoyl)-4(5)-(1-methylcyclohexyl)imidazole, b.p. 153.degree. - 157.degree. C./0.15 mm.

1-(N-methyl-N-3-methoxypropylcarbamoyl)-4(5)-(1-methylcyclohexyl)imidazole, b.p. 155.degree. - 160.degree. C./0.2 mm.

1-dimethylcarbamoyl-4(5)-(1,4-dimethylcyclohexyl)imidazole, b.p. 146.degree. - 148.degree. C./0.15 mm.

The current state of our knowledge indicates that the above compounds were obtained predominantly or substantially as the 4-substituted compounds.

To a solution of 12.8 g. 2-methyl-4(5)-(1-methylcyclopentyl)imidazole in a mixture of 60 ml. tetrahydrofuran and 20 ml. triethylamine was added 10.5 g. dimethylcarbamoyl chloride. The resulting mixture was boiled under reflux with stirring for 31/2 hours, then cooled and diluted with 250 ml. methylene chloride. The solution thus formed was washed with water and then dried over anhydrous magnesium sulphate. After evaporating the solvent, the liquid residue distilled to give the product, 1-dimethylcarbamoyl-2-methyl-4(5)-(1-methylcyclopentyl)imidazole, b.p. 124.degree. - 6.degree. C./0.1 mm. The current state of our knowledge indicates that this product was predominantly the 4-substituted derivative, 1-dimethylcarbamoyl-2-methyl-4-(1-methylcyclopentyl)imidazole.

The 2-methyl-4(5)-(1-methylcyclopentyl)imidazole used in the above reaction was prepared in the following way:

42 g. Bromomethyl 1-methylcyclopentyl ketone was added to a solution of 31.5 g. potassium acetate in 300 ml. methanol and the resulting mixture was refluxed on a steam bath for 2 hours. It was then cooled, filtered and the filtrate added with stirring to a solution of 83 g. cupric acetate monohydrate in a mixture of 500 ml. water and 435 ml. 25 percent ammonia. A solution of 18.5 g. acetaldehyde in 100 ml. water was then added and the mixture heated on a steam bath for five hours with constant stirring.

After cooling the cuprous salt of the imidazole was collected, washed with water and suspended in 270 ml. of 4N acetic acid. While stirring, a solution of 34 g. potassium ferricyanide in 100 ml. water was added, and the precipitated copper complex removed and washed well with water. The combined supernatant liquors were basified to pH 9 - 10 with 5N sodium hydroxide and extracted several times with ether. The ethereal extracts were combined, washed with water and dried over anhydrous sodium sulphate. After evaporation of the solvent, the residue was crystallized from acetone to give the novel imidazole, 2-methyl-4(5)-(1-methylcyclopentyl)imidazole, m.p. 108.degree. C.

In an analogous manner to that described above, there were prepared the following compounds:

1-dimethylcarbamoyl-2-ethyl-4(5)-(1-methylcyclopentyl)imidazole, b.p. 118.degree. - 120.degree. C./0.1 mm.

1-dimethylcarbamoyl-2-propyl-4(5)-(1-methylcyclopentyl)imidazole, b.p. 128.degree. - 130.degree. C./0.15 mm.

1-dimethylcarbamoyl-2-methyl-4(5)-(1-methylcyclohexyl)imidazole, b.p. 135.degree. - 136.degree. C./0.15 mm.

1-dimethylcarbamoyl-2-ethyl-4(5)-(1-methylcyclohexyl)imidazole, b.p. 134.degree. - 136.degree. C./0.1 mm.

1-dimethylcarbamoyl-2-propyl-4(5)-(1-methylcyclohexyl)imidazole, b.p. 140.degree. - 142.degree. C./0.1 mm.

1-(N-methyl-N-propylcarbamoyl)-2-methyl-4(5)-(1-methylcyclohexyl)imidazole b.p. 140.degree. - 144.degree. C./0.2 mm.

1-(N-methyl-N-ethylcarbamoyl)-2-methyl-4(5)-(1-methylcyclohexyl)imidazole, b.p. 133.degree. - 135.degree. C./0.25 mm.

1-dimethylcarbamoyl-2-methyl-4(5)-(1,3,3-trimethylcyclohexyl)imidazole, b.p. 132.degree. - 136.degree. C./0.15 mm.

1-morpholinocarbonyl-2-methyl-4(5)-(1-methylcyclohexyl)imidazole, m.p. 134.degree. C.

1-dimethylthiocarbamoyl-2-methyl-4(5)-(1-methylcyclohexyl)imidazole, b.p. 140.degree. - 144.degree. C./0.1 mm.

The current state of our knowledge indicates that these imidazoles were obtained predominantly or substantially as the 4-substituted compounds.

In the course of preparing the above imidazoles, the following novel intermediates were made:

2-ethyl-4-(1-methylcyclopentyl)imidazole, b.p. 128.degree. - 131.degree. C./0.1 mm., m.p. 87.degree. - 88.degree. C.

2-propyl-4-(1-methylcyclopentyl)imidazole, b.p. 132.degree. - 136.degree. C./0.15 mm.

2-methyl-4-(1-methylcyclohexyl)imidazole m.p. 112.degree. - 113.degree. C.

2-ethyl-4-(1-methylcyclohexyl)imidazole b.p. 136.degree. - 138.degree. C./0.15 mm.

2-propyl-4-(1-methylcyclohexyl)imidazole b.p. 140.degree. - 142.degree. C./0.15 mm.

2-methyl-4-(1,3,3-trimethylcyclohexyl)imidazole.

To a solution of 9.5 g. 2-ethyl-4-cyclopropylimidazole in 50 ml. dry tetrahydrofuran and 22 ml. triethylamine was added 8 g. dimethylcarbamoyl chloride. The resulting mixture was boiled under reflux for 31/2 hours, then cooled and diluted with 250 ml. methylene chloride. After washing with water, the methylene chloride solution was dried over magnesium sulphate. Evaporation of the solvent gave a residue which distilled under reduced pressure to give the product, 1-dimethylcarbamoyl-2-ethyl-4(5)-cyclopropylimidazole, b.p. 118.degree. - 119.degree. C./0.2 mm.

The current state of our knowledge indicates that this compound is 1-dimethylcarbamoyl-2-ethyl-4-cyclopropylimidazole.

The imidazole reactant was prepared in the following way:

110 g. Cyclopropane carbonylchloride dissolved in 150 ml. of absolute ether was added dropwise into an ice-cold solution of 91 g. diazomethane in 1500 ml. ether. After the addition was complete the temperature of the solution was allowed to rise to room temperature and to stand over night. The removal of the ether by distillation under reduced pressure left a yellow oil which was carefully mixed with 2000 ml. 2N sulphuric acid whilst cooling. This mixture was stirred at 50.degree. C. for 5 hours and was then cooled, neutralised with solid potassium carbonate and extracted with ether. The ethereal extract was evaporated the residue being distilled under reduced pressure to give cyclopropyl hydroxymethyl ketone, b.p. 56.degree. - 60.degree. C./10 mm.

A solution of 40 g. cyclopropyl hydroxymethyl ketone in 350 ml. methanol was added with stirring to a solution of 160 g. cupric acetate monohydrate in 840 ml. water and 840 ml. 25 percent ammonia, followed by the addition of 28 g. propionaldehyde. The resulting mixture was heated on a steam bath for five hours with constant stirring. Precipitation of the cuprous salt occurred and, after cooling, the precipitate was collected, washed with water and suspended in 450 ml. 4N-acetic acid. While stirring, a solution of 66.5 g. potassium ferricyanide in 200 ml water was added. The precipitated copper complex was removed and washed with water. The combined supernatant liquors were basified to pH 9 with 5N sodium hydroxide and extracted several times with ether. After combining the ethereal extracts, washing with water and drying over sodium sulphate, the solvent was evaporated. On standing the residue solidified and was crystallized from petroleum ether to give the novel 4-cyclopropyl-2-ethylimidazole, m.p. 104.degree. - 106.degree. C.

5.1 ml. Dimethylcarbamoyl chloride in 20 ml. dry dioxan was added to a mixture of 9.2 g. 2-ethylthio-4-tert.butylimidazole and 8.4 ml. triethylamine in 30 ml. dry dioxan. After heating the mixture on a steam bath for 24 hours, the triethylamine hydrochloride was removed and the product, 1-dimethylcarbamoyl-2-ethylthio-4(5)-tert.butylimidazole, distilled. It had a boiling point of 108.degree. - 111.degree. C. at 0.10 - 0.12 mm. Hg. and on cooling crystallised to a solid with a melting point of 45.degree. C. The present state of our knowledge indicates that this is the 4-substituted compound.

The 2-ethylthio-4-tert.butylimidazole employed in the above reaction was prepared in the following way.

104 g. Potassium phthalimide was suspended in a solution of 100 g. bromopinacolone in 300 ml. dry toluene. This reaction mixture was stirred on a steam bath for 18 hours and the solid precipitate filtered off and washed with toluene. The washings were added to filtrate which was heated on a steam bath in vacuo. The product, 3,3-dimethyl-1-phthalimidobutan-2-one, crystallised out on cooling. It was washed with light petroleum (b.p. 80.degree. - 100.degree. C.) and its melting point was 97.degree. - 101.5.degree. C. 82.6 g. 3,3-Dimethyl-1-phthalimidobutan-2-one was refluxed for 10 hours with a mixture of 460 ml. concentrated hydrochloric acid, 400 ml. water and 324 ml. acetic acid. The mixture was taken to dryness by means of a rotatory evaporator after which 360 ml. water was added and the solution chilled in ice. Phthalic acid was filtered off and the solution again taken to dryness, the residual solid being dissolved in warm absolute alcohol. Ether was added to the cooled solution and 1-amino-3,3-dimethylbutan-2-one hydrochloride precipitated as product, melting point 199.degree. - 200.degree. C.

35.2 g. 1-Amino-3,3-dimethylbutan-2-one hydrochloride and 30 g. potassium thiocyanate in 50 ml. water was warmed on the steam bath for 2 hours. After cooling, the solid formed was collected, washed with water, dried and recrystallised from industrial methylated spirit to give 4-tert.butylimidazole-2-thiol, melting point 232.degree. - 234.degree. C. A solution/suspension of this in industrial methylated spirit was added to a solution of 4.5 g. sodium hydroxide in 100 ml. water. 17.6 g. Ethyl iodide was added forming a lower layer and the mixture was shaken for two minutes whilst the ethyl iodide reacted and dispersed. After 20 minutes the alkali was neutralised by passing in carbon dioxide and the methylated spirit removed by evaporation. The solid was collected, washed with water, dried and on recrystallisation from toluene gave 2-ethylthio-4-tert.butylimidazole, melting point 116.5.degree. - 120.degree. C.

1.2 g. Sodium hydride in oil (50 percent dispersion) was added to 3.4 g. 2-methylthio-4-tert.butylimidazole in dry tetrahydrofuran. When the evolution of hydrogen had ceased, 2.7 g. dimethylcarbamoyl chloride was carefully added. Heat was evolved and a precipitate formed. After a period of an hour the solid was removed and the product distilled. It was 1-dimethylcarbamoyl-2-methylthio-4(5)-tert.butylimidazole, boiling point 107.degree. C. at 0.07 mm. Hg. pressure. The present state of our knowledge indicates that this is the 4-substituted compound.

The imidazole reactant used in the above preparation was prepared in an analogous way to that of 2-ethylthio-4-tert.butylimidazole described in Example 17.

The following compounds are prepared in an analogous way to that described in Example 17.

1-dimethylcarbamoyl-2-benzylthio-4(5)-tert.butylimidazole, m.p. 65.degree. - 67.degree. C.

1-dimethylcarbamoyl-2-(4-chlorobenzylthio)-4(5)-tert.butylimidazole, m.p. 96.degree. - 97.degree. C.

1-dimethylcarbamoyl-2-propylthio-4(5)-tert.butylimidazole, m.p. 69.degree. - 71.degree. C.

1-diethylcarbamoyl-2-methylthio-4(5)-tert.butylimidazole, b.p. 114.degree. - 116.degree. C./0.1 mm.

1-morpholinocarbonyl-2-methylthio-4(5)-tert.butylimidazole m.p. 70.degree. - 72.degree. C.

1-dimethylcarbamoyl-2-isopropylthio-4(5)-tert.butylimidazole, m.p. 64.degree. - 66.degree. C.

1-dimethylcarbamoyl-2-allylthio-4(5)-tert.butylimidazole, m.p. 65.degree. - 67.degree. C.

1-dimethylcarbamoyl-2-n.pentylthio-4(5)-tert.butylimidazole, b.p. 132.degree. - 136.degree. C./0.08 mm.

1-dimethylcarbamoyl-2-n.butylthio-4-(5)-tert.butylimidazole, b.p. 126.degree. - 128.degree. C./0.2 mm.

1-dimethylcarbamoyl-2-ethylthio-4(5)-sec.butylimidazole, b.p. 103.degree. C./0.08 mm.

1-dimethylcarbamoyl-2-methylthio-4(5)-sec.butylimidazole, b.p. 100.degree. C./0.05 mm.

1-dimethylcarbamoyl-2-propylthio-4(5)-sec.butylimidazole, b.p. 108.degree. C./0.06 mm.

1-dimethylcarbamoyl-2-ethylthio-4(5)-isopropylimidazole, b.p. 115.degree. C./0.11 mm.

1-dimethylcarbamoyl-2-methylthio-4-(5)-isopropylimidazole, b.p. 116.degree. - 120.degree. C./0.65 mm.

1-dimethylcarbamoyl-2-methylthio-4(5)-(1-methylcyclohexyl) imidazole, m.p. 75.degree. - 76.degree. C.

1-dimethylcarbamoyl-2-ethylthio-4(5)-(1-methylcyclohexyl) imidazole, m.p. 114.degree. - 117.degree. C.

1-dimethylcarbamoyl-2-propylthio-4(5)-(1-methylcyclohexyl) imidazole, m.p. 62.degree. - 64.degree. C.

1-dimethylcarbamoyl-2-methylthio-4(5)-(1-ethylpropyl) imidazole, b.p. 120.degree. - 122.degree. C./0.15 mm.

1-dimethylcarbamoyl-2-ethylthio-4(5)-(1-ethylpropyl) imidazole, b.p. 120.degree. - 122.degree. C./0.15 mm.

1-(N-methyl-N-ethylcarbamoyl)-2-ethylthio-4(5)-tert.butylimidazole, m.p. 93.degree. - 94.degree. C.

1-dimethylcarbamoyl-2-ethylthio-4(5)-cyclohexylimidazole, m.p. 148.degree. C.

1-dimethylcarbamoyl-2-ethylthio-4(5)-(1-methylcyclopentyl) imidazole, b.p. 126.degree. - 128.degree. C./0.05 mm.

1-dimethylcarbamoyl-2-(2-methylallylthio)-4(5)-tert.butylimidazole, b.p. 116.degree. - 118.degree. C./0.1 mm.

1-dimethylthiocarbamoyl-2-ethylthio-4(5)-(1-methylcyclohexyl)imidazole, b.p. 180.degree. - 190.degree. C./0.2 mm.

1-morpholinocarbonyl-2-ethylthio-4(5)-(1-methylcyclohexyl)imidazole, b.p. 186.degree. - 188.degree. C./0.2 mm.

1-dimethylcarbamoyl-2-ethylthio-4(5)-tert.pentylimidazole, b.p. 114.degree. - 116.degree. C./0.1 mm.

1-piperidinocarbonyl-2-ethylthio-4(5)-tert.butylimidazole, m.p. 63.degree. - 65.degree. C.

1-(n-methyl-N-2-methoxyethylcarbamoyl)-2-ethylthio-4(5)-tert.butylimidazole .

1-dimethylthiocarbamoyl-2-ethylthio-4(5)-tert.butylimidazole

1-pyrrolidinylcarbonyl-2-ethylthio-4(5)-tert.butylimidazole

1-dimethylcarbamoyl-2-(2,4-dichlorobenzylthio)-4(5)-tert.butylimidazole

1-(N-methyl-N-propylcarbamoyl)-2-ethylthio-4(5)-sec.butylimidazole

1-(N-methyl-N-ethylcarbamoyl)-2-methylthio-4(5)-sec.butylimidazole

1-dimethylthiocarbamoyl-2-allylthio-4(5)sec.butylimidazole

1-dimethylthiocarbamoyl-2-benzylthio-4(5)-sec.butylimidazole

1-(N-methyl-N-allylcarbamoyl)-2-ethylthio-4(5)-tert.butylimidazole

1-dimethylcarbamoyl-2-propylthio-4(5)-isopropylimidazole

1-(N-methyl-N-2-ethoxyethylcarbamoyl)-2-methylthio-4(5)-(1-methylcyclohexyl )imidazole

1-(N-methyl-N-2-ethoxyethylcarbamoyl)-2-allylthio-4(5)-sec.butylimidazole

1-diallylcarbamoyl-2-ethylthio-4(5)-tert.butylimidazole

In the course of preparing the above compounds the following imidazole intermediates were isolated. They were prepared in a way similar to that described for the preparation of 2-ethylthio-4-tert.butylimidazole in Example 17.

2-benzylthio-4-tert.butylimidazole, m.p. 133.degree. C.

2-(4-chlorobenzylthio)-4-tert.butylimidazole, m.p. 176.degree. C.

2-propylthio-4-tert.butylimidazole, m.p. 101.degree. - 103.degree. C.

2-methylthio-4-tert.butylimidazole, m.p. 149.degree..

2-isopropylthio-4-tert.butylimidazole, m.p. 160.degree. - 162.degree. C.

2-allylthio-4-tert.butylimidazole, m.p. 118.degree. - 119.degree. C.

2-n.pentylthio-4-tert.butylimidazole, m.p. 96.degree. - 98.degree. C.

2-n.butylthio-4-tert.butylimidazole, m.p. 79.degree. - 80.degree. C.

2-ethylthio-4-sec.butylimidazole, b.p. 115.degree.C/0.16 mm.

2-methylthio-4-sec.butylimidazole, m.p. 74.degree. C.

2-propylthio-4-sec.butylimidazole, b.p. 106.degree. C/0.04 mm.

2-ethylthio-4-isopropylimidazole, m.p. 96.degree. - 98.degree. C.

2-methylthio-4-isopropylimidazole, m.p. 96.degree. - 98.degree. C.

2-methylthio-4-(1-methylcyclohexyl)imidazole, b.p. 126.degree. - 130.degree. C/0.1 mm.

2-ethylthio-4-(1-methylcyclohexyl)imidazole, m.p. 74.degree. - 75.degree. C.

2-propylthio-4-(1-methylcyclohexyl)imidazole, m.p. 105.degree. - 106.degree. c.

2-methylthio-4-(1-ethylpropyl)imidazole, b.p. 116.degree. - 118.degree. C/0.2 mm.

2-ethylthio-4-(1-ethylpropyl)imidazole, b.p. 118.degree. - 120.degree. C/0.1 mm.

2-ethylthio-4-cyclohexylimidazole, m.p. 110.degree. - 111.degree. C.

2-ethylthio-4-(1-methylcyclopentyl)imidazole, m.p. 69.degree. - 70.degree. C.

2-(2-methylallylthio)-4-tert.butylimidazole, m.p. 104.degree. - 105.degree. C.

2-ethylthio-4-tert.pentylimidazole, m.p. 85.degree. C.

The following intermediates were prepared in a similar way to that described in Example 17:

4-sec.butylimidazole-2-thiol, m.p. 109.degree. - 112.degree. C.

4-isopropylimidazole-2-thiol, m.p. 147.degree. - 150.degree. C.

4-(1-methylcyclohexyl)imidazole-2-thiol, m.p. 205.degree. C.

4-(1-ethylpropyl)imidazole-2-thiol, m.p. 171.degree. C.

4-cyclohexylimidazole-2-thiol, m.p. 260.degree. - 261.degree. C.

4-(1-methylcyclopentyl)imidazole-2-thiol, m.p. 182.degree. - 183.degree. C.

4-tert.pentylimidazole-2-thiol, m.p. 174.degree. C.

To a stirred solution of 11.3 g. 2-methoxymethyl-4-tert.butylimidazole in 30 ml. tetrahydrofuran and 20 ml. triethylamine was added 8 g. dimethylcarbamoyl chloride. The resulting mixture was boiled under reflux for three hours and then diluted with methylene chloride, washed with water and the methylene chloride solution then dried over magnesium sulphate. Evaporation of the solvent left a residue which distilled under reduced pressure to give the product, 1-dimethylcarbamoyl-2-methoxymethyl-4(5)-tert.butylimidazole, b.p. 106.degree. - 108.degree. C./0.1 mm. The present state of knowledge indicates that this is the 4-substituted compound.

The imidazole reactant used in the above preparation was prepared in the following way.

To a solution of 123 g. potassium acetate in 1200 ml. methanol was added 143 g. bromopinacolone. This reaction mixture was refluxed for two hours, then cooled and filtered. The filtrate was added with stirring to a solution of 320 g. cupric acetate monohydrate in 1600 ml. 25 percent ammonia and 1400 ml. water, followed by addition of 100 g. 77 percent aqueous solution of methoxyacetaldehyde. The temperature of the reaction mixture was maintained at 30.degree. - 40.degree. C. for an hour and the mixture then heated on a steam bath for a further four hours. After cooling overnight, the insoluble copper salt was collected, washed with water and suspended in 500 ml. of 4N-acetic acid. A solution of 133 g. potassium ferricyamide in 400 ml. water was added and the precipitated copper complex removed and washed with water. The combined supernatant liquors were basified (pH. 9-10) with 5N-sodium hydroxide and extracted with ether. The etheral extracts were combined, washed with water and dried over magnesium sulphate. The solvent was evaporated and the residue crystallised from petroleum ether (b.p. 60.degree. - 80.degree. C.) to give the product, 2-methoxymethyl-4-tert.butylimidazole, m.p. 65.degree. - 66.degree. C.

The following compounds were prepared in an analogous manner.

1-dimethylcarbamoyl-2-methoxymethyl-4(5)-sec.butylimidazole, b.p. 108.degree. - 110.degree. C./0.01 mm.

1-dimethylcarbamoyl-2-methoxymethyl-4(5)-(1-ethylpropyl) imidazole, b.p. 118.degree. - 120.degree. C./0.1 mm.

1-dimethylcarbamoyl-2-methoxymethyl-4(5)-(1-methylcyclohexyl) imidazole, b.p. 145.degree. - 146.degree. C./0.1 mm.

1-dimethylcarbamoyl-2-methoxymethyl-4(5)-(1-methylcyclopentyl) imidazole, b.p. 132.degree. - 134.degree. C/0.2 mm.

1-morpholinocarbonyl-2-methoxymethyl-4(5)-(1-methylcyclopentyl) imidazole, m.p. 150.degree. - 152.degree. C.

1-(n-methyl-N-ethylcarbamoyl)-2-methoxymethyl-4(5)-tert.butylimidazole, b.p. 112.degree. - 114.degree. C/0.2 mm.

1-(N-methyl-N-ethylcarbamoyl)-2-methoxymethyl-4(5)-sec.butylimidazole, b.p. 116.degree. - 118.degree. C/0.25 mm.

1-dimethylcarbamoyl-2-methoxymethyl-4(5)-tert.pentylimidazole, b.p. 115.degree. C/0.2 mm.

1-morpholinocarbamoyl-2-methoxymethyl-4(5)-tert.pentylimidazole, b.p. 138.degree. - 140.degree. C/0.1 mm.

1-morpholinocarbamoyl-2-methoxymethyl-4(5)-tert.butylimidazole, m.p. 57.degree. - 58.degree. C.

The current state of our knowledge indicates that these imidazoles were obtained predominantly as the 4-substituted compounds.

The following intermediates were isolated in the course of preparing the above compounds.

2-methoxymethyl-4-sec.butylimidazole, b.p. 122.degree. - 124.degree. C/0.6 mm.

2-methoxymethyl-4(1-ethylpropyl)imidazole, b.p. 126.degree. - 128.degree. C./0.2 mm.

2-methoxymethyl-4-(1-methylcyclohexyl)imidazole, b.p. 142.degree. - 144.degree. C./0.5 mm.

2-methoxymethyl-4-(1-methylcyclopentyl)imidazole, b.p. 126.degree. - 128.degree. C./0.3 mm.

2-methoxymethyl-4-tert.pentylimidazole, b.p. 116.degree. - 118.degree. C/0.4 mm.

The following carbamoylimidazole compounds of general formula I (X=oxygen) were prepared in a similar way to that described in Example 18. The present state of our knowledge indicates that they were obtained predominantly or entirely as the 4-substituted compounds.

The following imidazoles of general formula II were isolated, being prepared in a way similar to that described for the preparation of 2-ethylthio-4-tert.butylimidazole in Example 17.

Intermediates 4-R.sup.4 -Imidazole-2-thiol were prepared in a similar way to that described in Example 17.

1.8 g. Of sodium hydride in mineral oil (50 percent dispersion) was added gradually to a solution of 5.4 g. 4-isopropyl-2-methylthioimidazole in 30 ml. dry tetrahydrofuran. After a period of 30 minutes, 5.05 g. morpholinocarbonyl chloride was added. Heat was evolved and the mixture refluxed for an hour. The tetrahydrofuran was filtered and evaporated to give a residue which on crystallisation from petroleum ether (b.p. 100.degree.-120.degree. C.) gave the product, 1-morpholinocarbonyl-2-methylthio-4(5)-isopropylimidazole, m.p. 63.degree. - 65.degree. C. The present state of our knowledge indicates that this is the 4-substituted compound.

The imidazole reactant used in the above preparation was prepared in the following way:

126 g. 3-Methylbutan-2-one in 600 ml. methanol was treated with 74 ml. bromine which was added dropwise at a temperature of about 10.degree. C. The solution was quenched on ice and the bromoketone then separated and washed with water. The aqueous liquors were extracted with three 50 ml. portions of petroleum ether and the combined bromoketone and petrol portions added to 216 g. potassium phthalimide in 500 ml. dimethylformamide. The mixture was then heated with stirring on a steam bath for two hours then filtered to remove insoluble matter and poured into three liters of water with stirring. The solid was collected, dried, and recrystallised from industrial methylated spirit, 3-methyl-1-phthalimidobutan-2-one, m.p. 98.degree. - 99.degree. C.

176.3 g. Of the phthalimidoketone was refluxed for 20 hours with a mixture of one liter of concentrated hydrochloric acid, 1020 ml. water and 710 ml. acetic acid. The solution was evaporated and the residue taken up in 800 ml. water. After separation of phthalic acid, the solution was evaporated to dryness. The solid was air-dried to free it from excess acid, 1-amino-3-methylbutan-2-one hydrochloride, m.p. 155.degree. - 158.degree. C.

An aqueous solution of 98.8 g. of the aminoketone and 63.6 g. potassium thiocyanate was heated on a steam-bath for 21/2 hours. The oil which deposited solidified to give 4-isopropylimidazole-2-thiol, m.p. 147.degree. - 150.degree. C.

A solution of 6.16 g. potassium hydroxide in 50 ml. industrial methylated spirit was added to 14.2 g. 4-isopropylimidazole-2-thiol in 150 ml. industrial methylated spirit, followed by 15.6 g. methyl iodide. The solution was refluxed for 11/2 hours and the solvent then evaporated. After treating the residue with water the remaining solid was collected and recrystallised from ethyl acetate. It was 2-methylthio-4-isopropylimidazole, m.p. 96.degree. - 98.degree. C.

The following compounds of general formula I were prepared in an analogous manner. The present state of our knowledge indicates that they were obtained predominantly or entirely as the 4-substituted compounds.

17.0 g. 2-Methylthio-4-tert.butylimidazole were dissolved in 200 ml. of dry dioxan. after which 13.9 ml. of triethylamine and 12.3 g. dimethylthiocarbamoyl chloride were added. The mixture was refluxed for eight hours, then cooled and the precipitate of triethylamine hydrochloride filtered off. On distilling off the dioxan a brown oil remained. This oil was extracted with two 50 ml. portions of petroleum ether (b.p. 60.degree. - 80.degree. C.) and on cooling a solid was deposited which was collected and recrystallised from petroleum ether (b.p. 80.degree. - 100.degree. C.) with charcoal to give 1-dimethylthiocarbamoyl-2-methylthio-4(5)-tert.butylimidazole, m.p. 94.degree. - 96.degree. C. The present state of our knowledge indicates that this is the 4-substituted compound.

The following compounds were prepared in an analogous manner:

1-dimethylthiocarbamoyl-2-ethylthio-4(5)-(1-methylcyclohexyl) imidazole, b.p. 180.degree. - 190.degree. C/0.2 mm.

1-dimethylthiocarbamoyl-2-methylthio-4(5)-tert.pentylimidazole, b.p. 126.degree. - 130.degree. C/0.1 mm.

A solution of 7 g. 2-methylthio-4-tert.butylimidazole in 45 ml. dry tetrahydrofuran was added to 2.42 g. sodium hydride in mineral oil (60 percent dispersion). The resulting mixture was cooled to a temperature of between 0.degree. and 5.degree. C. and then 10 g. of 1-(N-methyl-N-2-ethoxyethyl)carbamoyl chloride added whilst the reaction mixture was maintained below 5.degree. C. After filtering to remove solid precipitate the filtrate was refluxed on a steam bath for 2 hours. On distillation the product, 1-(N-methyl-N-2-ethoxyethyl) carbamoyl-2-methylthio-4(5)-tert.butylimidazole, was collected, b.p. 130.degree. - 134.degree. C/0.1 mm. Hg pressure. The present state of our knowledge indicates that this was predominantly the 4-substituted compound.

The following compound was also prepared by a similar method 1-(N-methyl-N-2-ethoxyethyl)carbamoyl-2-methylthio-4(5)-isopropylimidazole , b.p. 132.degree. - 134.degree. C/0.1 mm.

This example illustrates an alternative method of preparing the intermediate 2-methylthio-4-tert.butylimidazole by a route which comprises reacting a .alpha.-haloketone with an S-alkylisothiouronium salt.

A mixture of 17.9 g. .alpha.-bromopinacolone, 16.7 g. S-methyl-iso-thiouronium sulphate and 32 g. sodium carbonate in 100 ml. water and 100 ml. ethanol was stirred under reflux for a period of 1 hour. The ethanol was distilled off and after the addition of a further quantity of 100 ml. water, 150 ml. toluene was added. The mixture was stirred vigorously for ten minutes and the hot toluene separated and washed with 100 ml. hot water. 70 ml. Of the toluene and traces of water were distilled off and the remaining toluene solution stirred at 0.degree. C. for 30 minutes when crystalline 2-methylthio-4-tert.butylimidazole separated. The product was filtered off, washed with cold toluene and dried, m.p. 149.degree. - 150.degree. C.

A concentrated solution of 1.2 g. 1-dimethylcarbamoyl-2-methylthio-4-(5)-tert.butylimidazole in 50 ml. ether was added to a concentrated solution of 1.5 g. flavianic acid in 4 l. ether. The flavianic crystallised on standing and was filtered off, m.p. 205.degree. - 206.degree. C with decomposition. On recrystallisation from industrial methylated spirits a pure sample was obtained, m.p. 206.degree. C. with decomposition.

In a similar manner the following acid addition salts were prepared:

An emulsifiable concentrate suitable for dilution with water to form an aqueous emulsion was prepared from the following ingredients:

Similar emulsifiable concentrates were prepared in which the imidazole compound in the above formulation was replaced by the following compounds of Example 3:

1-dimethylthiocarbamoyl-4(5)-tert.butylimidazole

1-(N-methyl-N-ethylcarbamoyl)-4(5)-tert.butylimidazole

1-(N-methyl-N-propylcarbamoyl)-4(5)-tert.butylimidazole

1-dimethylcarbamoyl-2-ethyl-4(5)-methylimidazole

1-dimethylcarbamoyl-4(5)-n-pentylimidazole

Emulsifiable concentrates suitable for dilution with water to form an aqueous emulsion were prepared from the following ingredients:

Emulsifiable concentrates containing the following compounds were prepared.

1-dimethylcarbamoyl-4(5)-isobutylimidazole

1-dimethylcarbamoyl-4(5)-(1-ethylpropyl)imidazole

1-dimethylcarbamoyl-4(5)-sec.butylimidazole

1-dimethylcarbamoyl-4(5)-isopropylimidazole

1-dimethylcarbamoyl-4(5)-sec.butylimidazole

1-dimethylcarbamoyl-4(5)-propylimidazole

1-dimethylcarbamoyl-4(5)-tert.pentylimidazole

1-(N-2-ethoxyethyl-N-methylcarbamoyl)-4(5)-tert.butylimidazole

Granules containing 5% w/w of the imidazole compound of Example 1 were prepared by impregnating granules of fuller's earth (mesh size 20/40 British Standard Sieve) with a solution of the imidazole compound in xylene and then evaporating the xylene from the impregnated granules.

Granules containing 5% w/w of the 1-dimethylcarbamoyl-4(5)-(1-methylcyclohexyl)imidazole were prepared by impregnating granules of fuller's earth (mesh size 20/40 British Standard Sieve) with a solution of the imidazole compound in xylene and then evaporating the xylene from the impregnated granules.

An emulsifiable concentrate suitable for dilution with water to form an aqueous emulsion was prepared from the following ingredients:

Similar emulsifiable concentrates were prepared in which the imidazole compound in the above formulation was replaced by the remaining compounds of the invention described in EXAMPLE 11.

A dispersible powder was prepared from the following ingredients:

Dyapol PT is an anionic dispersant based on the sodium salt of a sulphonated condensation product of urea/formaldehyde and cresol.

Emulsifiable concentrates suitable for dilution with water to form an aqueous emulsion were prepared from the following ingredients:

Emulsifiable concentrates containing the following compounds were prepared:

1-dimethylcarbamoyl-2-methylthio-4(5)-tert.butylimidazole

1-dimethylcarbamoyl-2-ethylthio-4(5)-tert.butylimidazole

1-dimethylcarbamoyl-2-methoxymethyl-4(5)-tert.butylimidazole

1-morpholinocarbonyl-2-methylthio-4(5)-tert.butylimidazole

Granules containing 5% w/w of the carbamoylimidazole compounds of Examples 17 and 18 were prepared by impregnating granules of fuller's earth (mesh size 20/40 British Standard Sieve) with a solution of the carbamoylimidazole compound in xylene and then evaporating the xylene from the impregnated granules.

Dispersible powders were prepared from the following ingredients:

Dispersible powders containing the following compounds were prepared:

1-dimethylcarbamoyl-2-methylthio-4(5)-tert.butylimidazole

1-dimethylcarbamoyl-2-ethylthio-4(5)-tert.butylimidazole

1-dimethylcarbamoyl-2-methoxymethyl-4(5)-tert.butylimidazole

1-morpholinocarbonyl-2-methylthio-4(5)-tert.butylimidazole

Broad bean plants 3-5 cm. high were infested with aphids (Megoura viciae) and then sprayed with an aqueous dispersion containing 250 parts per million w/v of the imidazole compound of Example 1. Each plant was kept under a lamp glass for 24 hours and then examined. It was found that a complete kill of the aphids had been obtained. The aphid populations of control plants that had been treated with an aqueous spray not containing any test compound were not affected.

Broad bean plants 3-5 cm. high were infested with aphids (Megoura viciae) and then sprayed with an aqueous dispersion containing 250 parts per million w/v of each of the carbamoyl imidazole compounds described in Example 11. Each plant was kept under a lamp glass for 24 hours and then examined. It was found that all of the compounds completely kill off the aphids. The aphid populations on control plants that had been treated with an aqueous spray not containing any test compound were not affected.

Broad bean plants 3-5cm. high were infested with aphids (Megoura viciae) and then sprayed with an aqueous dispersion containing 250 parts per million w/v of each of the carbamoyl imidazole compounds described in Examples 2 to 8 and 12 to 16. Each plant was kept under a lamp glass for 24 hours and then examined. It was found that all of the compounds gave at least a 50 percent control of the aphids. The aphid populations on control plants that had been treated with an aqueous spray not containing any test compound were not affected.

Hop leaves infested with the hop aphid, Phorodon humuli, were treated with aqueous dispersions of various compounds.

Ten leaves were taken from each of four replicate plants and the average number of aphids per leaf calculated. The hop plants were sprayed with an aqueous dispersion of the test compound till run off. Assessment one day after spraying showed that with an aqueous dispersion containing 0.03 percent by weight of the test compound, the following compounds achieved over 50 percent kill.

1-dimethylcarbamoyl-4(5)-tert.buytylimidazole

1-dimethylcarbamoyl-4(5)-isopropylimidazole

1-dimethylcarbamoyl-4(5)-(1-ethylpropyl)imidazole

1-dimethylcarbamoyl-4(5)-sec.butylimidazole

1-dimethylthiocarbamoyl-4(5)-sec.butylimidazole

1-dimethylcarbamoyl-4(5)-propylimidazole

1-dimethylcarbamoyl-4(5)-(1-methylcyclohexyl)imidazole

1dimethylcarbamoyl-4(5)-tert.pentylimidazole

An assessment of ovo-larvicidal activity against Tetranychus urticae was made in the following way.

Freshly laid eggs of Tetranychus urticae on a French bean leaf disc 2 cm. in diameter were sprayed with an aqueous dispersion of the compound test. After ten days any live larvae on the leaf disc were counted and the percentage mortality assessed. Triplicate assessments were made at various concentrations of test compound in order to obtain approximately LD.sub.50 values, expressed as p.p.m. w/v of test compound.

The following two compounds were found to have an LD.sub.50 below 250 p.p.m.:

1-dimethylcarbamoyl-4(5)-(1-methylcyclopentyl)imidazole

1-dimethylcarbamoyl-4(5)-(1-methylcyclohexyl)imidazole.

An assessment of the activity of 1-dimethylcarbamoyl-4(5)-tert.butylimidazole against the green rice leafhopper was made in the following way.

The roots of a rice seedling were dipped in an aqueous emulsion containing 0.005% by weight of the test compound. The rice seedling was enclosed in a glass cylinder into which fifteen adult green rice leafhoppers were inserted and the temperature was maintained at 25.degree. C. After 48 hours the insect mortality was observed. It was found that a complete kill of the insects had occurred.

Broad bean plants 3-5 cm. high were infested with aphids (Megoura viciae) and then sprayed with an aqueous dispersion containing 250 parts per million w/v of the following compounds:

1-dimethylcarbamoyl-2-methylthio-4(5)-tert.butylimidazole

1-dimethylcarbamoyl-2-ethylthio-4(5)-tert.butylimidazole

1-dimethylcarbamoyl-2-methoxymethyl-4(5)-tert.butylimidazole

1-morpholinocarbonyl-2-methylthio-4(5)-tert.butylimidazole

1-morpholinocarbonyl-2-methylthio-4(5)-isopropylimidazole

Each plant was kept under a lamp glass for 24 hours and then examined. It was found that a complete kill of the aphids had been obtained. The aphid populations of control plants that had been treated with an aqueous spray not containing any test compound were not affected.

Broad bean plants 3-5 cm. high were infested with aphids (Megoura viciae) and then sprayed with an aqueous dispersion containing 250 parts per million w/v of the carbamoylimidazole compounds of Examples 17, 18 and 20-24. Each plant was kept under a lamp glass for 24 hours and then examined. It was found that at least 50 percent of the aphids were killed. The aphid populations of control plants that had been treated with an aqueous spray not containing any test compound were not affected.

Broad bean plants 3-5 cm. high were infested with blackbean aphids (Aphis fabae) and then sprayed with an aqueous dispersion containing 100 parts per million w/v of each active compound listed below. The plants were kept under a lamp glass for 24 hours and then examined. In all cases at least 50 percent of the aphids were killed. The aphid populations of control plants that had been treated with an aqueous spray not containing any test compound were not affected.

1-dimethylcarbamoyl-2-methylthio-4(5)-tert.butylimidazole

1-morpholinocarbonyl-2-methylthio-4(5)-tert.butylimidazole

1-morpholinocarbonyl-2-methylthio-4(5)-sec.butylimidazole

1-morpholinocarbonyl-2-methylthio-4(5)-isopropylimidazole

1-morpholinocarbonyl-2-methylthio-4(5)-1-ethylpropylimidazole

1-dimethylcarbamoyl-2-methylthio-4(5)-isobutylimidazole

The compounds to be tested were applied as soil drenches. 25 ml. Of an aqueous test solution was watered into the soil in an 8 cm. diameter plant pot containing a single broad bean plant. A cardboard shield was placed around the plant so that only a part of it protruded. This was infested with aphids (Megoura viciae). After three days the aphicidal effect was assessed by counting the numbers of live and dead aphids.

The following compounds were found to have an LD.sub.50 of less than 100 p.p.m.

1-dimethylcarbamoyl-2-methylthio-4(5)-tert.butylimidazole

1-dimethylthiocarbamoyl-2-methylthio-4(5)-tert.butylimidazole

1-morpholinocarbonyl-2-methylthio-2-methylthio-4(5)-tert.butylimidazole

1-dimethylcarbamoyl-2-allylthio-4(5)-sec.butylimidazole

1-dimethylcarbamoyl-2-ethylthio-4(5)-(1-methylcyclopentyl) imidazole

1-dimethylcarbamoyl-2-but-2-enylthio-4(5)-tert.pentylimidazole

Ten larvae of the cabbage white butterfly (Pieris brassicae) were placed in a tube together with a square of cabbage leaf which had been dipped in a test solution containing 1-dimethylcarbamoyl-2-methylthio-4(5)-tert.butylimidazole and allowed to dry. After 24 hours untreated cabbage was added as food and after a further twenty-four hours an assessment was made of the mortality of the larvae by counting the numbers of live and dead insects.

Two replicates were carried out employing a test solution of 200 p.p.m. At this level of concentration the active compound gave greater than 50 percent control of the larvae.