2-Substituted Adenosine 5'-Carboxamides as Antihypertensive Agents

A mixture of 1.15 g of 2-(2-phenethylamino)-2',3'-0-isopropylidene-adenosine-5'-(N-ethyl)-carboxa mide and 25 ml of 1N hydrochloric acid is heated at 65.degree. for 1 hour The reaction mixture is neutralized and the product is extracted with ethyl acetate. After drying over MgSO.sub.4, the solvent is removed in vacuo and the residue is triturated with ether to afford 2-(2-phenethylamino)-adenosine-5'-(N-ethyl)-carboxamide, m.p. 115.degree.-118.degree. .

The starting material is prepared as follows:

A mixture of 1.04 g of 2-chloro-2',3'-O-isopropylidene-adenosine-5'-(N-ethyl)-carboxamide (U.S. Pat. No. 4,167,565) and 8 g of 2-phenethylamine is heated at 130.degree. for 2 hours. After cooling the excess 2-phenethylamine is removed in vacuo and the residue is chromatographed on silica gel with 5% methanol in methylene chloride as the eluent to afford 2-(2-phenethylamino)-2',3'-O-isopropylidene-adenosine-5'-(N-ethyl)-carboxa mide.

Prepared in a similar manner are:

(a) 2-(2-phenethylamino)-adenosine-5'-(N-cyclopropyl)carboxamide, m.p. 115.degree.-118.degree.;

(b) 2-(p-methoxy-2-phenethylamino)-adenosine-5'-(N-ethyl)-carboxamide, m.p. 110.degree.-115.degree.;

(c) 2-(p-chloro-2-phenethylamino)-adenosine-5'-(N-elhyl)-carboxamide, m.p. 110.degree.-115.degree.;

(d) 2-(2-phenethylamino)-adenosine-5'-(N-methyl)carboxamide, m.p. 188.degree.-190.degree.;

(e) 2-(2-phenethylamino)-adenosine-5'-(N-2-hydroxy-ethyl)-carboxamide, m.p. 157.degree.-160.degree.;

(f) 2-(p-fluoro-2-phenethylamino)-adenosine-5'-(N-ethyl)-carboxamide, m.p. 108.degree.-112.degree.;

(g) 2-[p-(2-carboxyethyl)-2-phenethylamino]-adenosine5'-(N-ethyl)-carboxamide, m.p. 197.degree.-202.degree.; hydrochloride salt, m.p. 200.degree.-203.degree.; tromethamine salt, m.p. 100.degree.; sodium salt, m.p. 160.degree.-165.degree..

The amine starting material is prepared as follows:

A mixture of 5 g of p-bromophenylacetonitrile, 4.6 ml of t-butyl acrylate, 57 mg of palladium diacetate, 310 mg of tri-o-tolylphosphine and 12 ml of triethylamine is refluxed for 5 hours. The reaction mixture is diluted with ethyl acetate and washed with 10% HCl and saturated sodium bicarbonate solution. After drying over magnesium sulfate the solvent is removed in vacuo to yield t-butyl p-(cyanomethyl)-phenylacrylate. This material is dissolved in ethanol and hydrogenated over 1.1 g of 10% palladium on carbon catalyst for 3 days at 3 atmospheres pressure of hydrogen. After filtration the solvent is removed in vacuo and the residue is chromatagraphed on silica gel with ether/hexane (1:1) as the eluent to afford p-(2-t-butoxycarbonyl-ethyl)-phenyl-acetonitrile; 2.8 g of this material is dissolved in 90 ml of tetrahydrofuran and 50 ml of methanol and to this is added 6.2 g of cobalt chloride in 90 ml of water followed by 2.1 g of sodium borohydride in small portions. After filtration and removal of solvent, the residue is chromatagraphed on silica gel with 7.5% ammonia saturated methanol in methylene chloride as the eluent to afford p-(2-t-butoxy-carbonyl-ethyl)-2-phenethylamine as an oil.

(h) 2-p-(2-carboxyethenyl)-2-phenethylamino]-adenosine-5'-(N-ethyl)-carboxamid e hydrochloride, m.p. 178.degree.-181.degree..

The starting material is prepared by reduction of t-butyl p-(cyanomethyl)-phenylacrylate (as obtained in example 2 g) to p-t-butoxycarbonyl-ethenyl)-2-phenethylamine with sodium borohydride and cobalt chloride as described under g) above.

(i) 2-[p-(carboxymethoxy)-2-phenethylamino]-adenosine-5'-(N-ethyl)-carboxamide hydrochloride, m.p. 137.degree.-141.degree.;

The amine starting material is prepared as follows:

A mixture of 3 g of p-hydroxyphenylacetonitrile, 3.6 ml of t-butyl bromoacetate, 6.5 g of potassium carbonate in 45 ml of dimethylformamide is stirred at room temperature for 16 hours. After dilution with water the product is extracted with ether. The ethyl layer is washed with 1N sodium hydroxide, dried over magnesium sulfate and the solvent removed in vacuo to yield p-(t-butoxycarbonylmethoxy)-phenylacetonitrile which is reduced to p-(t-butoxycarbonylmethoxy)-2-phenethylamine with sodium borohydride/cobalt chloride as described for the starting material under (g).

(j) 2-(S-2-phenylpropylamino)-adenosine-5'-(N-ethyl)carboxamide, m.p. 117-121.degree. , prepared from the levorotatory (S)-2-phenylpropylamine, J. Med. Chem. 17, 717 (1974);

(k) 2-(N-methyl-2-phenethylamino)-adenosine-5'-(N-ethyl)-carboxamide, hydrochloride, m.p. 115.degree.-119.degree., prepared from N-methylphenethylamine;

(1) 2-(p-carboxymethyl-2-phenethylamino)-adenosine-5'-(N-ethyl)-carboxamide hydrochloride, m.p. 140.degree.-145.degree..

The amine starting material for compound (1) is prepared as follows:

A mixture of 20 g of p-bromophenylacetic acid, 30 ml of ether, 1 ml of sulfuric acid and 35 ml of isobutylene is shaken in a sealed bottle for 24 hours. The reaction mixture is diluted with ether and washed with sodium hydroxide solution. After drying over magnesium sulfate the ether is removed in vacuo to afford the t-butyl ester as an oil. A mixture of 9.6 g of this material is refluxed with a mixture of 6.1 g of N-vinylphthalimide, 160 mg of palladium acetate, 800 mg of tri-o-tolylphosphine, 10 ml of acetonitrile and 8 ml diisopropylethylamine for 24 hours. The reaction is diluted with water, the resulting precipitate is collected and recrystallized from methanol/methylene chloride. The resulting solid is hydrogenated at 4 atmospheres pressure over 2 g of 10% palladium on carbon catalyst in 100 ml of ethanol and 100 ml of tetrahydrofuran for 16 hours at room temperature. After removal of the solvent in vacuo the residue is heated at reflux with 10 ml of hydrazine hydrate and 20 ml of ethanol for 2 hours. The reaction is diluted with ether and washed with 5% potassium hydroxide solution. The ether is dried over magnesium sulfate solution and the solvent is removed in vacuo. The residue is chromatographed on silica gel, with 5% ammonia saturated methanol in methylene chloride as the eluent, to afford p-(t-butoxycarbonylmethyl)-2-phenethylamine as an oil.

(m) 2-[p-(dimethylaminocarbonylmethyl)-2-phenethylamino]-adenosine-5'-(N-ethyl )-carboxamide.

The amine starting material is prepared as follows:

A mixture of 6 g of p-bromophenylacetic acid in 100 ml of methylene chloride and 5 ml of oxalyl chloride is stirred at room temperature for 16 hours. After removal of the solvent in vacuo the residue is dissolved in methylene chloride and treated with excess dimethylamine at room temperature. After 1 hour the reaction mixture is washed with water, the organic layer is dried over magnesium sulfate and the solvent is removed in vacuo to afford p-bromo-N,N-dimethyl-phenylacetamide as an oil, which is converted to p-(dimethylaminocarbonylmethyl)-2-phenethylamine as described for the starting material under 1).

(n) 2-(2-cyclohexylethylamino)-adenosine-5'-(N-ethyl)carboxamide hydrochloride, m.p. 154.degree.-157.degree.;

(o) 2-(2-cyclopentylethylamino)-adenosine-5'-(N- ethyl)-carboxamide;

(p) 2-(N-methyl-2-cyclohexylethylamino)-adenosine-5'- (N-ethyl)-carboxamide;

(q) 2-(p-carboxy-2-phenethylamino)-adenosine-5'-(N-ethyl)-carboxamide. The amine starting material is prepared using methodology under (1) from p-bromobenzoic acid.

The following compounds of formula Ia wherein R.sub.3 ' represents hydroxy can be prepared substantially according to the procedures previously described herein.

The starting material for compound (a) is prepared as follows: To a cooled mixture of 30.6 g of m-methoxybenzenethiol, 54.4 g of 45% potassium hydroxide in 100 ml of dimethsulfoxide is added 36.0 g of alipha-(bromomethyl)acrylic acid in 25 ml of dimethylsulfoxide at such a rate as to maintain the reaction temperature at 50.degree.-55.degree.. After 1 hour the reaction mixture is diluted with water and washed with ether. After acidification, the product is extracted with ether, the organic layer is dried over magnesium sulfate and the solvent is removed in vacuo to afford alpha-(3-methoxybenzenethiomethyl)acrylic acid. This material is dissolved in 570 ml of o-dichlorobenzene and 7.2 g of triethylamine and heated to 200.degree. for 5 hours. After cooling, the products are extracted with sodium bicarbonate solution, the aqueous layer is acidified and the products extracted with ether. After drying over magnesium sulfate, the solvent is removed in vacuo to afford a mixture of 3,4-dihydro-5-methoxy-2-H[1]-benzothiopyran-3-carboxylic acid and 3,4-dihydro-7-methoxy-2H-[1]-benzothiopyran-3-carboxylic acid.

This mixture of acids is dissolved in 500 ml of t-butyl alcohol and treated with 17 g of triethylamine and 36 ml of diphenylphosphoryl azide. After 5 hours reflux, the solvent is removed in vacuo and the residue is dissolved in ether and washed with 1N sodium hydroxide and 1N hydrochloric acid. After drying over magnesium sulfate, the solvent is removed in vacuo and the residue is chromatographed in silica gel (1 kg) with ether/hexane (1:4) as the eluent to afford in succession N-t-butoxy-carbonyl-3,4-dihydro-5-methoxy-2H-[1]-benzothiopyran-3-amine and N-t-butoxycarbonyl-3,4-dihydro-7-methoxy-2H-[1]-benzothiopyran-3-amine

A solution of 10 g of N-t-butoxycarbonyl-3,4-di-hydro-5-methoxy-2H-[1]-benzothiopyran-3-amine in 30 ml of trifluoroacetic acid is kept at room temperature for 1 hour. The solvent is removed in vacuo, the residue is treated with 1N NaOH and the product is extracted with ether. After drying over magnesium sulfate, the solvent is removed in vacuo to afford 3,4-dihydro-5-methoxy-2H-[1]-benzothiopyran-3-amine as an oil.

A mixture of 2.70 g of 2-[p-(2-t-butoxycarbonyl-ethyl)-2-phenethylamino]-2',3'-O-isopropylidene-a denosine-5'-(N-ethyl)-carboxamide and 45 ml of lN hydrochloric acid is heated at 65.degree. for 1 hour. The reaction mixture is cooled, the resulting precipitate is collected, washed first with ice water and then with a mixture of ethyl acetate and ether to yield 2-[p-(2-carboxyethyl)-2-phenethylamino]-adenosine-5'-(N-ethyl)-carboxamide hydrochloride, m.p. 200.degree.-203.degree. (of example 2 g);

The starting material is prepared as follows:

A mixture of 2.31 g of t-butyl p-(cyanomethyl)phenylacrylate (example 2g), 6.28 g of concentrated aqueous ammonium hydroxide and 0.46 g of 5% rhodium on alumina in 50 ml of absolute ethanol is hydrogenated at 3 atmospheres pressure and room temperature for 22 hours. A second portion of 0.46 g of rhodium on alumina is added and hydrogenation is continued for 6 more hours. The reaction mixture is filtered, the catalyst is washed with ethanol, and the filtrate is evaporated to dryness. The residue is dissolved in 50 ml of ethyl acetate, hydrogen chloride gas is bubbled into the solution for 10 minutes and the solution is evaporated to dryness. The product is triturated with ether and collected to yield p-(2-t- butoxycarbonylethyl)-2-phenethylamine hydrochloride which is then converted to the free base.

A mixture of 4.0 g of 2-chloro-2',3'-O-isopropylidene-adenosine-5'-(N-ethyl)-carboxamide and 14.0 g of p-(2-t-butoxycarbonylethyl)-2-phenethylamine is heated at 130.degree. for 3 hours. The reaction mixture is dissolved in methylene chloride, the solution is washed with sodium bicarbonate solution and evaporated to dryness. The residue is crystallized from ether to yield 2-[p-(2-t-butoxycarbonylethyl)-2-phenethylamino]-2',3'-O-isopropylidene-ad enosine-5'-(N-ethyl)-carboxamide, m.p. 180.degree. .

A solution of 12 mg of 2.beta.-{2-[p-(2-t-butoxycarbonyl-ethyl)-2-phenethylamino]-9-adenyl}-3-alp ha-hydroxy-2,3-dihydrofuran-5-N-ethylcarboxamide in 1.5 ml of ethanol to which is added 10 mg of 5% rhodium on carbon is hydrogenated at room temperature and 3 atmospheres pressure for 30 hours. The catalyst is filtered off and the solution is evaporated to dryness to yield a mixture of isomers comprising 2-[p-(2-carboxyethyl)-2-phenethylamino]-3'-deoxyadenosine-5'-(N-ethyl)-car boxamide; NMR (CD.sub.30 D): 8.0 (s,1H), 5.93 (d,1H).

The starting material is prepared as follows:

Sodium hydride (6 mg of 60% dispersion in mineral oil) is added to a solution of 20 mg of 2-[p-(2-t-butoxy-carbonylethyl)-2-phenethylamino]-2',3'-O-isopropylidene-a denosine-5'-(N-ethyl)-carboxamide in 25 ml of anhydrous isopropanol. The reaction mixture is heated at 70.degree. for 6 hours. The reaction mixture is cooled and the reaction is quenched with 0.5 ml pH6 phosphate buffer, and the mixture is evaporated to dryness. The resulting product is chromatographed on silica gel eluting with 10% methanol in methylene chloride to yield 2-{2.beta.-[p-(2-t-butoxycarbonyl-ethyl)-2-phenethylamino]-9-adenyl}-3-alp ha-hydroxy-2,3-dihydrofuran-5-N-ethylcarboxamide as an oil; NMR (CD.sub.3 OD): 7.82 (s,1H), 6.36 (d,1H), 6.1 (d,1H), 5.52 (t,1H).

(a) A mixture of 1.05 g of 2-[p-(2-carboxyethyl)-2phenethylamino]-adenosine-5'-(N-ethyl)-carboxamide sodium salt and 314 mg of ethyl iodide in 10 ml of dimethylformamide is stirred at room temperature for 16 hours. The reaction mixture is poured onto water and the product is extracted with ethyl acetate. After drying over magnesium sulfate the solvent is removed in vacuo and the residue is triturated with ether to afford 2-[p-(2)carboxyethyl)-2-phenethylamino]-adenosine-5'-(N-ethyl)-carboxamide ethyl ester m.p. 81.degree.-89.degree., the compound of formula IIa wherein R.sub.4, represents ethyl, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 represent hydrogen, and R.sub.9 represents p-(2-ethoxycarbonylethyl)-phenyl.

Prepared in a similar fashion are the following:

(b) 2-[p-(2-carboxyethyl)-2-phenethylamino]-adenosine5'-(N-ethyl)-carboxamide pivaloyloxymethyl ester, m.p. 85.degree.-89.degree.;

(c) 2-[p-(2-carboxyethyl)-2-phenethylamino]-adenosine5'-(N-ethyl)-carboxamide methyl ester, m.p. 90.degree.-95.degree.;

(d) 2-[p-(2-carboxyethyl)-2-phenethylamino]-adenosine5'-(N-ethyl)-carboxamide 2-N,N-dimethylaminoethyl ester;

(e) 2-[p-(2-carboxyethyl)-2-phenethylamino]-adenosine-5'-(N-ethyl)-carboxamide n-butyl ester, m.p. 68.degree.-75.degree..

The following compounds can be prepared substantially according to the procedures described herein.

(a) 2-(3-cyclohexylpropylamino)-adenosine-5'-(N-ethyl)-carboxamide hydrochloride, m.p. 175.degree.-181.degree.;

(b) 2-(4-cyclohexylbutylamino)-adenosine-5'-(N-ethyl)carboxamide hydrochloride, m.p. 130.degree.-134.degree.;

(c) 2-[2-(2-norbornanyl)-ethylamino]-adenosine-5'-N-ethylcarboxamide;

(d) 2-[2-(1-adamantyl)-ethylamino]-adenosine-5'-N-ethylcarboxamide;

(e) 2-[2-(1-cyclohexenyl)-ethylamino]-adenosine-5'-N-ethylcarboxamide;

(f) 2-[2-(tetrahydropyran-4-yl)-ethylamino]-adenosine-5'-N-ethylcarboxamide; t he starting 2-(tetrahydro-pyran-4-yl)-ethylamine can be prepared from tetrahydropyran-4-one e.g. by Wittig condensation with diethyl cyanomethyl phosphonate followed by hydrogenation and reduction with lithium aluminum hydride.

(g) 2-(p-hydroxy-2-phenethylamino)-adenosine-5'-(N-ethyl)-carboxamide, m.p. 110.degree.-116.degree..

(h) 2-(3-phenylpropylamino)-adenosine-5'-(N-ethyl)carboxamide, hydrochloride salt, m.p. 114.degree.-120.degree..

(i) 2-(4-phenylbutylamino)-adenosine-5'-(N-ethyl)carboxamide, hydrochloride salt, m.p. 115.degree.-120.degree..

(j) 2-[p-carboxyethyl)-2-phenethylamino]-adenosine-5'-(N-ethyl)-carboxamide benzyl ester, m.p. 75.degree.-80.degree..

(k) 2-(.beta.-hydroxy-.beta.-methyl-2-phenethylamino)-adenosine-5'-(N-ethyl)-c arboxamide, m.p. 124.degree.-130.degree., alpha]D=+4.94.degree. (EtOH), prepared from R(-)-.beta.-hydroxy-.beta.-methyl-2-phenethylamine.

(l) 2-(.beta.-hydroxy-.beta.-methyl-2-phenethylamino)-adenosine-5'-(N-ethyl)-c arboxamide, m.p. 115.degree.-120.degree., alpha].sub.D =+29.06.degree. (EtOH), prepared from S(+)-.beta.-hydroxy-.beta.-methyl-2-phenethylamine.

A solution of 2-(p-hydroxy-2-phenethylamino)-adenosine-5'-(N-ethyl)-carboxamide (170 mg) in dimethylformamide (1 mL) is treated with 0.3 M aqueous disodium hydrogen phosphate (0.65 mL) followed by chloramine T hydrate (17.8 mg) and sodium iodide (117 mg). After 3 hours of stirring, chloramine-T hydrate (17.8 mg) and sodium iodide (117 mg) are again added and the whole stirred overnight. More chloramine-T (17.8 mg) is added and after a further 3 hour period, the solvent is removed under high vacuum and the residue treated with excess aqueous sodium thiosulfate and extracted with ethyl acetate. The organic extract is washed with brine, dried over sodium sulphate and chromatographed over silica gel with 10% methanol in methylene chloride as eluent. The desired fractions are combined and concentrated to dryness at reduced pressure to afford 2-[(4-hydroxy-3-iodo)2-phenethylamino]-adenosine-5'-(N-ethyl)-carboxamide, m.p. 131.degree.-140.degree..

A mixture of 2-[p-(2-carboxyethyl)-2-phenethylamino]-adenosine-5'-(N-ethyl)-carboxamide benzyl ester (0.4 g), pyridine (10 mL) and acetic anhydride (1 mL) is stirred at room temperature under nitrogen for 2 hours. The mixture is concentrated under high vacuum, taken up in ethyl acetate, washed with cold dilute sodium bicarbonate solution, washed with brine, dried over sodium sulfate and concentrated to dryness to afford 2-[p-(2-carboxyethyl)-2-phenethylamino]-2'3'-di-O-acetyl-adenosine-5'-(N-e thyl)-carboxamide benzyl ester as an oil.

A solution of 2-[p-(2-carboxyethyl)-2-phenethylamino]-2'3'-di-O-acetyl-adenosine-5'-(N-e thyl)-carboxamide benzyl ester (0.45 g) in ethanol (100 mL) is hydrogenated at 50 p.s.i. at room temperature over 5 hours in the presence of 10% Pd on carbon (0.5 g). The mixture is filtered and the filtrate concentrated to dryness to afford 2-[p-(2-carboxyethyl)-2-phenethylamino]-2',3'-di-O-acetyl-adenosine-5'-(N- ethyl)-carboxamide, m.p. 113.degree.-117.degree., [alpha].sub.D =+5.0.degree. (c=1.28, MeOH).

Prepared similarly to procedures described in examples 9 and 10 are:

(a) 2-[p-(2-carboxyethyl)-2-phenethylamino]-2',3-di-O-n-propionyl-adenosine-5' -(N-ethyl)-carboxamide;

(b) 2-carboxyethyl)-2-phenethylamino]-2',3'-di-O-butyryl-adenosine-5'-(N-ethyl )-carboxamide;

(c) 2-[p-(2-carboxyethyl)-2-phenethylamino]-2,3'-di-O-benzoyl-adenosine-5'-(N- ethyl)-carboxamide;

(d) 2-[p-(2-carboxyethyl)-2-phenethylamino]-2,3'-di-O-nicotinoyl-adenosine-5'- (N-ethyl)-carboxamide.

A mixture of 500 mg of 2-[p-(2-carboxyethyl)-2-phenethylamino]-adenosine-5'-(N-ethyl)-carboxamide , 205 mg of 1,3-dicyclohexylcarbodiimide and 122 mg of phenethylamine in 15 ml of methylene chloride is stirred overnight at room temperature. The reaction is poured into 50 ml of methylene chloride and washed with 25 ml of 10% aqueous sodium bicarbonate and 25 ml of water. The organic layer is dried over magnesium sulfate and evaporated to give a crude product which is purified by flash column chromatography using 9:1 methylene chloride-methanol saturated with ammonia to give 2-[p-(2-phenethylaminocarbonylethyl)- 2-phenethylamino]-adenosine-5'-(N-ethyl)-carboxamide.

The following compounds of formula I wherein R and R.sub.2 represent hydrogen, R.sub.3 represents hydroxy and R.sub.4 represents ethyl can be prepared substantially according to procedures described above.

(a) Preparation of 10,000 tablets each containing 10 mg of the active ingredient:

Formula:

Procedure:

All the powders are passed through a screen with openings of 0.6 mm. Then the drug substance, lactose, magnesium stearate and half of the starch are mixed in a suitable mixer. The other half of the starch is suspended in 65 ml of water and the suspension added to the boiling solution of the polyethylene glycol in 260 ml of water. The paste formed is added to the powders, which are granulated, if necessary, with an additional amount of water. The granulate is dried overnight at 35.degree., broken on a screen with 1.2 mm openings and compressed into tablets, using concave punches uppers bisected.

(b) Preparation of 1,000 capsules each containing 10 mg of the active ingredient: Formula:

Procedure:

All the powders are passed through a screen with openings of 0.6mm. Then the drug substance is placed in a suitable mixer and mixed first with the magnesium stearate, then with the lactose and starch until homogeneous. No. 2 hard gelatin capsules are filled with 300 mg of said mixture each, using a capsule filling machine.

(c) Similarly prepared are capsules and tablets comprising other compounds exemplified herein, e.g. 2-(2-cyclohexylethyl)-adenosine-5'-(N-ethyl)-carboxamide, 2-[p-(2-carboxyethyl)-2-phenethylamino]-adenosine-5'-(N-ethyl)-carboxamide ethyl ester.