Fungicides

The invention is illustrated in the following Examples. Structures of isolated novel compounds were confirmed by elemental and/or other appropriate analyses.

2-(2-Carboxyphenyl)acetic acid (9 g) and 4-chloroaniline (6.3 g) in mesitylene (200 ml) were heated at reflux for 18 h, under Dean and Stark conditions. On cooling, the crude product crystallised out and was filtered off. Recrystallisation from ethanol/ethyl acetate gave 2-(4-chlorophenyl)isoquinoline-1,3(2H,4H )-dione, m.p. 178.degree.-80.degree. C. A mixture of this product (2.8 g) and phosphoryl chloride (10 ml) was heated at reflux for 21 h, and excess phosphoryl chloride was then eveporated at reduced pressure. The residue was stirred in ice-water for 4 h. and the precipitate filtered off and suspended in 2% aqueous sodium bicarbonate for 5 minutes. It was again filtered off, taken up in dichloromethane (150 ml) dried and evaporated. Column chromatography of the residue gave a brown solid, which was recrystallised from isooctane/ethyl acetate, to give 3-chloro-2-(4-chlorophenyl)isoquinolin-1(2H)-one m.p. 125.degree.-7.degree. C.

This product (0.58 g), and 1,2,4-triazol-1 -ylsodium (0.37 g) were stirred in dry dimethylformamide (10 ml) at 100.degree. C. for 4 h. The mixture was then cooled, poured into water (20 ml) and extracted with dichloromethane. The combined organic extracts were washed with water (20 ml), dried and evaporated. The residue was purified by column chromatograhhy and recrystallised from hexane/ethyl acetate to give 2-(4-chlorophenyl)-3-(1,2,4-triazol-1-yl)- isoquinolin-1(2H)-one, m.p. 154.5.degree.-155.5.degree. C. (Compound 1).

In a similar manner there was obtained in turn

(a) 2-(2,4-dichlorophenyl)isoquinoline-1,3(2H,4H)-dione, m.p. 168.degree.-169.degree. C.,

(b) 3-chloro-2-(2,4-dichlorophenyl)isoquinoline-1(2H)-one, m.p. 119.5.degree.-121.degree. C., and

(c) 2-(2,4-dichlorophenyl)-3-(1,2,4-triazol-1-yl)isoquinoline-1(2H)-one, m.p. 137.degree.-137.5.degree. C. (Compound 2)

(a) 2-(2,4,6-trichlorophenyl)isoquinoline-1,3(2H,4H)-dione, m.p. 149.5.degree.-150.degree. C., and

(b) 3-chloro-2-(2,4,6-trichlorophenyl)isoquinoline-1(2H)-one, which then gave

(i) 2-(2,4,6-trichlorophenyl)-3-(1,2,4-triazol-1-yl)-isoquinoline-1(2H)-one, m .p. 148 (Compound 3), and

(ii) 2-(2,4,6-trichlorophenyl)-3-(imidazol-1-yl)isoquinoline-1(2H)-one, m.p. 198.5.degree.-199.degree. C., (Compound 4),

A mixture of 2',4'-dichloroacetophenone (19.4 g) and selenium dioxide (13.9 g) in pyridine (150 ml) was stirred at reflux for 16 h. After cooling the insoluble material was removed by filtration and a pyridine solution (30 ml) of o-phenylenediamine (11.1 g) was added to the filtrate. This solution was heated at reflux for 2 hr, cooled and concentrated in vacuo. The residue was stirred with ether (250 ml) and 10% hydrochloric acid (80 ml) and filtered to give 3-(2,4-dichlorophenyl)quinoxalin-2(1H)-one m.p. 300.degree. C.(d).

A mixture of this product (9.6 g) phosphoryl chloride (150 ml) and dimethylformamide (5 ml) was heated at reflux for 3 h, cooled and poured onto ice-cold water (11). After 1 h the brown solid was removed by filtration to give 2-chloro-3-(2,4-dichlorophenyl)quinoxaline, m.p. 140.degree.-50.degree. C. A mixture of this crude product (6.2 g), 1,2,4-triazole (1.38 g, 0.02 m) and potassium carbonate (2.76 g, 0.02 m) in acetonitrile (150 ml) was stirred at reflux for 18 h. The mixture was filtered whilst warm, and the solid washed with acetonitrile (5.0 ml) and ethyl acetate (50 ml). The filtrate was concentrated in vacuo and the residue was flash chromatographed on silica using petroleum ether (b.p. 60.degree.-80.degree. C.)/ethyl acetate (1:1) as eluent. The product was recrystallised from absolute ethanol and ethyl acetate, to give 3-(2,4-dichlorophenyl)-2-(1,2,4-triazol-1-yl)quinoxallne, m.p. 193.degree.-195.degree. C. (Compound 5).

In a similar manner there was obtained

(a) 3-(2,4-dichlorophenyl)-6,7-dimethylquinoxalin-2-one, m.p. 324.degree.-6.degree. C.(d), which was converted to 2-chloro-3-(2,4-dichlorophenyl-6,7-dimethylquinoxaline, m.p. 162.degree.-4.degree. C., which was then converted to 3-(2,4-dichlorophenyl)-6,7-dimethyl-2-(1,2,4-triazol1-yl)-quinoxaline, m.p. 173.degree.-6.degree. C. (Compound 6); and

(b) 2-chloro-3-(4-chlorophenyl)quinoxaline, m.p. 169.degree.-70.degree. C. which was converted to 3-(4-chlorophenyl)-2-(1,2,4-triazol-1-yl)quinoxaline m.p. 163.degree.-6.degree. C. (Compound 7). This last reaction was carried out using sodium hydride as the base instead of potassium carbonate.

In a similar manner to that described in Example 2, 3-chloro-2-(2,4-dichlorophenyl)-2H-indazole was reacted in the presence of potassium carbonate in dimethylformamide

(a) with 1,2,4-triazole, to give 2-(2,4-dichlorophenyl)-3-(1,2,4-triazol-1-yl)-2H-indazole, m.p. 112.5.degree.-113.5.degree. C. (Compound 8), and

(b) with imidazole, to give 2-(2,4-dichlorophenyl)-3-(imidazol-1-yl)-2H-indazole, m.p. 116.5.degree.-118.5.degree. C. (Compound 9).

2,4-Dichlorophenylacetyl chloride (0.075 mol) was added dropwise over 1 h to a stirred solution of aniline (6.8 g) and triethylamine (7.6 g) in dry ether (200 ml) at 0.degree.-5.degree. C. The reaction mixture was allowed to warm up to room temperature overnight. It was then poured into iced water. An oily layer separated out and gradually solidified. This was recrystallised from diisopropyl ether to give 2-(2,4-dichlorophenyl)acetanilide, m.p. 145.6.degree.-146.5.degree. C.

Phosphoryl chloride (27.6 ml) was added dropwise over 20 minutes to cooled (0.degree. C.) and vigorously stirred dry dimethylformamide (4.95 ml). 2-(2,4-Dichlorophenyl)acetanilide (12 g) was added and the mixture stirred at 0.degree. C. for 5 minutes and then at 75.degree. C. for 8 h. The cooled reaction mixture was poured into iced water and extracted with ether. The combined ethereal exrracts were washed with water, dried and solvent removed in vacuo. Flash chromatography followed by trituration with ether gave 2-chloro-3-(2,4-dichlorophenyl)quinoline, m.p. 120.degree.-122.5.degree. C.

This was then treated with 1,2,4-triazole, in the presence of potassium carbonate in dimethylformamide to give 3-(2,4-dichlorophenyl)-2-(1,2,4-triazol-1-yl)quinoline, m.p. 157.degree.-158.5.degree. C. (Compound 10) Example 5

A slurry of stannous chloride dihydrate (18 g) in concentrated hydrochloric acid (40 ml) was added slowly at 50.degree. C. to a suspension of 2,4-dichloro-2'-nitrodiphenylamine (5.6 g) in absolute ethanol (50 ml. The temperature rose to 55.degree. C. and the mixture then heated at reflux for 4 hrs. It was then cooled to room temperature and slowly poured into 40% aqueous sodium hydroxide (100 ml), diluted with water and extracted with dichloromethane. The extract was dried, and concentrated in vacuo to give a brown oil which was triturated with petrolemm ether (b.p. 40.degree.-60.degree. C.) to give a grey solid. This was filtered and recrystallised from petroleum ether (b.p. 40.degree.-60.degree. C.) to give N-(2, 4-dichlorodiphenyl)-o-phenylenediamine, m.p. 62.degree.-4.degree. C. This product (31.9 g) and urea (15.1 g) were heated at 165.degree.-70.degree. C. for 5 h. After cooling, the solid mass was broken up and stirred with water (33 ml) and ether (150 ml). The solid was filtered and recrystallised from ethyl acetate to give 1-(2,4-dichlorophenyl)benzimidazolin-2-one, m.p. 213.degree.-6.degree. C.

A suspension of this product (20 g) in phosphoryl chloride (250 ml) and N,N-dimethylaniline (17.3 g) was heated at reflux for 7 hr. After cooling the excess phosphoryl chloride and N,N-dimethylaniline were removed by distillation in vacuo. The residual oil was poured onto ice/water (11) and then extracted with ethyl acetate, dried, and concentrated in vacuo to give a green oil. This was triturated with ether to give a solid which was removed by filtration and the ethereal filtrate was concentrated in vacuo. The residue was chromatographed on silica using dichloromethane as the eluent to give 2-chloro-1-(2,4-dichlorophenyl)benzimidazole, m.p. 80.degree.-3.degree. C.

This was treated with imidazole and potassium carbonate in dimethylformamide as described in Example 1 to give 1-(2,4-dichlorophenyl)-2-(imidazol-1-yl)benzimidazole, m.p. 147.degree.-51.degree. C. (Compound 11).

In a similar manner there was also obtained 1-(2,4-dichlorophenyl)-2-(1,2,4-triazol-1-yl)benzimidazole, m.p. 180.degree.-3.degree. C. (Compound 12).

A solution of 2-bromo-2'-hydroxyacetophenone (11.25 g) in acetonitrile (25 ml) was added dropwise, wirh stirring and cooling, to a solution of 1,2,4-triazole (3.45 g) and triethylamine (5.05 g) in acetonitrile (75 ml). The temperature was maintained at -20.degree. C. for 3 hours with continued stirring. The reaction mixture was allowed to warm to room temperature and stirred overnight. The mixture was filtered and the solvent evaporated. The residue was triturated with ethyl acetate and some solid filtered off. The filtrate was chromatographed using ethyl acetate as eluent to give crude 2'-hydroxy-2-(1,2,4-triazol-1-yl)acetophenone. Triethylamine (0.71 g) was added to a solution of this product (1.4 g) in tetrahydrofuran (30 ml). The mixture was stirred at room temperature and 2,4-dichlorobenzoyl chloride (1.45 g) in tetrahydrofuran (20 ml) was added dropwise. The reaction was exothermic and the mixture was stirred at room temperature overnight, then refluxed and stirred for 4 hours. The mixture was cooled, filtered and evaporated. The residue was triturated with diisopropyl ether and filtered to give 2-(2,4-dichlorophenyl)-3-(1,2,4-triazol-1-yl)benzo-1-pyran-4-one, m.p. 226.degree.-8.degree. C. (Compound 13).

In a similar manner there was obtained 2'-hydroxy-2-(imidazol-1-yl)acetophenone which was converted to 2-(2,4-dichlorophenyl)-3-(imidazol-1yl)-benzopyran-4-one, m.p. 195.degree.-200.degree. C. (Compound 14).

4-Chlorobenzaldehyde (1.18 g) was added to 2'-hydroxy-2-(1,2,4-triazol-1-yl)acetophenone, obtained in Example 6 (1.7 g), in dry dimethylformamide (20 ml). The mixture was stirred at 90.degree. C. for 24 hours. It was then poured into ice/water, extracted with dichloromethane and the extract dried and evaporated. The residual oil was triturated with diisopropyl ether to give 2-(4-chlorophenyl)-2,3-dihydro-3-(1,2,4-triazol-1-yl)-benzopyran-4-one, m.p. 140.degree.-1.degree. C. (Compound 15).

2-Azido-4-chlorobenzoic acid (130 g) was stirred with thionyl chloride (52 ml) in dry toluene at room temperature for 24 hours. the solution was evaporated to give crude 2-azido-4-chlorobenzoyl chloride. This product (14.2 g) was added to a solution of 2,4-dichloroaniline (10.65 g) in dry pyridine (70 ml) and the mixture stirred for 25 mins. It was then poured into ice-water and the precipitate filtered off, washed with water, sucked dry, heated in boiling ethanol and the residue filtered off, washed with ethanol and air-dried to give 2-azido-4-chloro-N-(2,4 dichlorophenyl)benzamide, m.p. 169.5.degree. C. (dec.)

This product (18.43 g) was heated under reflux in thionyl chloride (60 ml) for 22 hours. Excess thionyl chloride was evaporated under reduced pressure and the residue extracted with dichloromethane and worked up to give 3,6-dichloro-2-(2,4-dichlorophenyl)-2H-indazole, m.p. 119.5.degree.-120.degree. C. This was reacted in the presence of potassium carbonate in dimethylformamide in a similar manner to that described in Example 3 with imidazole, to give 2-(2,4-dichlorophenyl)-6-chloro-3-(1,2,4-triazol-1-yl)-2H-indazole, m.p. 112.5.degree.-113.5.degree. C. (Compound 16).

Compounds are assessed for activity against one or more of the following:

Erysiphe graminis: barley powdery mildew (EG)

Plasmopara viticola: vine downy mildew (PV)

Botrytis cinerea: grey mould of tomato (BC)

Puccinia recondita: brown wheat rust (PR)

Aqueous solutions or dispersions of the compounds at the desired concentration, including a wetting agent, were sprayed onto the appropriate plant and then inoculated by spraynng with spore suspensions of the fungi or by dusting or shaking diseased material over the treated plants for the E. graminis. Plants were then kept under controlled environment conditions suitable for maintaining plant growth and development of the disease. After an appropriate time, the degree of infection of the leaf surface was visually estimated.

Compounds were considered active if they gave greater than 50% control of the disease at a concentration of 500 ppm (w/v) or less.

Activities were demonstrated as follows (+=active).