2-SELENOMETHYL-1, 4-DIHYDROPYRIDINES, A PROCESS FOR THE PREPARATION THEREOF AND PHARMACEUTICAL COMPOSITIONS CONTAINING THEM

Abstract: Compounds of formula I wherein: R₁ is a cyano, nitro, acetyl, benzoyl or alkoxycarbonyl group; R₂ is an optionally substituted phenyl or hetaryl group; R₃ is an alkoxycarbonyl group; R₄ is an alkyl group, optionally substituted by hydroxy, amino, phenyl, heterocyclic group; an optionally substituted phenyl group or an heterocyclic group. Compounds I are useful in human therapy as agents able to interact with Ca⁺⁺-dependent systems and as anti-tumor agents.

Description: The present invention relates to 2-selenomethyl-1,4-dihydropyridines, to a process for the preparation thereof and to pharmaceutical compositions containing them. 2-oxymethyl-1,4-dihydropyridines are described in EP-A 60674 2-thiomethyl-1,4-dihydropyridine are subject of WO-A-87 100 836. The compounds of the invention have the following general formula I wherein: R₁ is a _COOR, nitro or cyano group; R₂ is phenyl or phenyl substituted by one or more halogen atoms, nitro cyano, C₁-C₆-alkylthio, R₃ is a COOR group; R₄ is a C₁-C₆ alkyl group, substituted by amino, a phenyl group or a group of formula wherein X is a halogen atom and R₅ and R₆, are hydrogen, and R is a C₁-C₄-alkyl group or a C₁-C₄ alkyl group substituted by C₁-C₆-alkoxy. The present invention further relates to the salts of compounds I with pharmaceutically acceptable acids or bases, and possible enantiomers, diastereoisomers and mixtures thereof. Preferred compounds according to the invention are those in which R₁ is a methoxycarbonyl, ethoxycarbonyl, isopropoxycarbonyl, methoxyethoxycarbonyl, nitro or cyano group; R₂ is phenyl, m-nitro-phenyl, m-chloro-phenyl, m-cyano-phenyl, o-nitro-phenyl, o-methylthiophenyl, m-methylthiophenyl group; R₃ is a methoxycarbonyl or ethoxycarbonyl group and R₄ is a phenyl, 2-aminoethyl or isouronium hydrochloride group. The compounds of the invention are prepared by reacting compounds of general formula II: wherein R₁, R₂ and R₃ have the above mentioned meanings; with a compound of general formula III: R′₄ Se ⊖ M ⊕ wherein R′₄ has the above defined meanings of R₄, with the exception of group of formula (R₅, R₆ and X as above), and M ⊕ is the cation of an alkali or alkaline-earth metal. The reaction is carried out in inert solvents, such as lower alcohols, dioxane, tetrahydrofuran, 1,2-dimethoxyethane, chloroform, 1,2-dichloroethane or mixtures thereof, at a temperature from _20°C to the reflux temperature of the solvent mixture, for reaction times from a few minutes to some hours. The compounds of general formula III are preferably prepared in situ from compounds of general formula IV: R′₄ _ Se _ Se _ R′₄ wherein R′₄ is as above defined, by reduction of the selenium-selenium bond; said reaction is carried out by known methods, in the same solvents above indicated, for example by reaction with reducing agents such as sodium borohydride, lithium borohydride, zinc borohydride, lithium alluminium hydride: the resulting solution of compound III is used as such for the reaction with compounds of formula II. Compounds of formula II are disclosed in EP-A-0.212.340 in the Applicant's name. Compounds of formula IV are known, easily available compounds. Compounds of formula I in which R₄ is an isouronium group are obtained by reaction of a compound of formula II with a compound of formula V: wherein R₅ and R₆, are hydrogen. The reaction is carried out in inert solvents, such as lower alcohols, acetone, benzene, acetonitrile, dioxane, 1,2-dimethoxyethane, ethyl acetate, 1,2-dichloroethane and mixtures thereof, at a temperature from room temperature to the reflux temperature of the mixture, for times ranging from a few minutes to 24 hours. Compounds of formula V are known in literature and easily available. The compounds of the present invention might be useful in therapy as anti-tumor agents because they inhibit "in vitro" the growth of tumoral cells, whilst "in vivo" they increase the survival time of animals infected by experimental tumors. Further, compounds of the invention proved to interact with Ca⁺⁺-dependent systems; particularly, they showed to have Ca⁺⁺-antagonistic action "in vitro" (test of rat aorta), and can displace 3H-nitrendipine from dihydropyridine receptor. Some of the compounds show anti-hypertensive activity, some other have protective action on the oxidative damages of the cell membranes while some other more are useful as anti-aging agents, i.e. they are able to counteract cellular aging process. For the intended therapeutical uses, compounds of formula I are conveniently administered in form of parenteral or oral pharmaceutical compositions. Examples of compositions for parenteral administration, particularly by intravenous or intraarterial route, are sterile aqueous solutions, sterile powders for extemporary preparation of a solution with a suited solvent, oily preparations for intramuscular or intraperitoneal administration. Examples of compositions for oral administration comprise capsules, tablets, syrups or granulates. The compositions of the present invention are prepared by means of conventional techniques and excipients, such as those described in "Remington's Pharmaceutical Sciences Handbook", Hack Publishing Company, New York, USA. The treatment Scheme, such as dosage, time, frequence of administration, use of particular therapeutic protocols, will depend on the severity of the pathology to be treated and on the conditions of the patient (weight, sex and age), and will be accordingly determined by the experts, according to well-established indications in medical practice. The dosage will be comprised from 10 to 1.000 mg/day, optionally subdivided in more administrations. EXAMPLE 1 180 mg of sodium borohydride was added portionwise to a diphenyl diselenide (0.66 g) ethanolic solution (5 ml), kept under nitrogen at room temperature. After 30 minutes, the mixture was cooled and a 2-chloromethyl-3-carboethoxy-5-carbomethoxy-4-(m-nitrophenyl)-6-methyl-1,4-dihydropyridine (1,60 g) ethanol solution (10 ml) was dropped therein. The reaction mixture was stirred at 0°C for 1 hour, kept to room temperature for 6 hours and neutralized with a monobasic sodium phosphate saturated solution, evaporated under vacuum to small volume, taken up in ethyl acetate (80 ml) and washed with water (3 × 50 ml). The organic layer was dried over sodium sulfate and evaporated under vacuum. After purification by column chromatography (SiO₂, eluent ethyl ether-ethyl acetate 80/20) 1.8 g of 2-phenylselenylmethyl-3-carboethoxy-5-carbomethoxy-4-(m-nitrophenyl)-6-methyl-1,4-dihydropyridine was obtained. 1H-NMR: (CDCl₃) δ: 1.00-1.20 (3H, t); 2.10(3H, s); 3.80(3H, s); 4.00-4.40(4H, m); 5.10(1H, s); 6.80(1H, m); 7.00-8.10(9H, m). EXAMPLE 2 Using the appropriate 2-chloromethyl-1,4-dihydropyridines, under the above indicated conditions, the following compounds were obtained: 2-phenylselenylmethyl-3,5-dicarbomethoxy-4-phenyl-6-methyl-1,4-dihydropyridine; 2-phenylselenylmethyl-3,5-dicarboethoxy-4-(m-chlorophenyl)-6-methyl-1,4-dihydropyridine; 2-phenylselenylmethyl-3-carbomethoxy-4-(m-cyano-phenyl)-5-isopropoxycarbonyl-6-methyl-1,4-dihydropyridine; 2-phenylselenylmethyl-3-carbethoxy-4-(o-nitro-phenyl)-5-methoxy-ethoxycarbonyl-6-methyl-1,4-dihydropyridine; 2-phenylselenylmethyl-3-carboethoxy-4-(o-methylthiophenyl)-5-carbomethoxy-6-methyl-1,4-dihydropyridine; 2-phenylselenylmethyl-3,5-dicarbomethoxy-4-(m-methyl thiophenyl)-6-methyl-1,4-dihydropyridine; 2-phenylselenylmethyl-3-carboethoxy-4-(m-nitrophenyl)-5-nitro-6-methyl-1,4-dihydropyridine; EXAMPLE 3 300 mg of NaBH₄ was added portionwise to a selenocystamine (320 mg) aqueous solution (3 ml), under nitrogen bubbling. After about 1 hour, the yellow solution discolourized and, after dilution with ethanol (10 ml) and cooling to 0°C, a 2-chloromethyl-3-carboethoxy-5-carbomethoxy-4-(o-methylthiophenyl)-6-methyl-1,4-dihydropyridine (0.700 g) solution in ethanol (10 ml) was dropped therein. The mixture was stirred at 0°C for 2 hours, then at room temperature for a night, neutralized with a monobasic sodium phosphate saturated solution and evaporated under vacuum; the residue was treated with ethyl acetate (60 ml) and washed with water (5 × 20 ml). The organic layer was dried and concentrated under vacuum, the residue was purified by column chromatography (SiO₂, eluent chloroform-methanol-triethylamine 90/10/1). 0.8 g of 2-(2-aminoethyl)-selenylmethyl-3-carboethoxy-5-carbomethoxy-4-(o-methylthiophenyl)-6-methyl-1,4-dihydropyridine was obtained; 1H-NMR(CDCl₃) _ δ 1.10-1.30(3H, t); 2.10(3H, s); 2.20-3.20(6H, m); 3.70(3H, m); 3.90-4.30(7H, m); 7.00-8.20(5H, m). EXAMPLE 4 Operating under the same conditions of Example 3, the following compounds were obtained: 2-(2-aminoethyl)selenylmethyl-3,5-dicarbomethoxy-4(m-nitrophenyl)-6-methyl-1,4-dihydropyridine; 2-(2-aminoethyl)selenylmethyl-3-carbethoxy-4(o-methylthiophenyl)-5-carbomethoxy-6-methyl-1,4-dihydropyridine; 2-(2-aminoethyl)selenylmethyl-3,5-dicarboethoxy-4(m-methylthiophenyl)-6-methyl-1,4-dihydropyridine; 2-(2-aminoethyl)selenylmethyl-3-carboethoxy-4(m-nitrophenyl)-5-cyano-6-methyl-1,4-dihydropyridine; 2-(2-aminoethyl)selenylmethyl-3-carboethoxy-4(m-methylthiophenyl)-5-nitro-6-methyl-1,4-dihydropyridine. EXAMPLE 5 A solution of selenylurea (370 mg) and 2-chloromethyl-3,5-dicarboethoxy-4-(m-nitrophenyl)-6-methyl-1,4-dihydropyridine (1 g) in ethanol (25 ml) was refluxed for 2 hours under nitrogen atmosphere, thereafter solvent was evaporated to dryness, the residue was taken up into ethyl ether (50 ml) and the precipitated solid was filtered. 1.2 g of -[(6-methyl-3,5-dicarboethoxy-4-(m-nitrophenyl)-1,4-dihydropyridin-2-yl)methyl]isoselenouronium chloride was obtained. 1H-NMR: (DMSO-d₆): δ 1.00-1.30(6H, t); 2.20(3H, s); 3.80-4.20(3H, q); 4.50(2H, m); 5.00(1H, S); 7.10-8.10(5H, m); 8.50-10.00(4H, m). EXAMPLE 6 Operating analogously to what described in Example 5, the following compounds were further obtained: [(6-methyl-3-carboethoxy-4-(m-nitrophenyl)-5-carbomethoxy-1,4-dihydropyridin-2-yl)methyl]isoselenouronium chloride; [(6-methyl-3-carboethoxy-4-(o-methylthiophenyl)-5-carbomethoxy-1,4-dihydropyridin-2-yl)methyl]isoselenouronium chloride; [(6-methyl-3,5-dicarboethoxy-4-(m-methylthiophenyl)-1,4-dihydropyridin-2-yl)methyl]isoselenouronium chloride.

Claims: Claims for the Contracting States: AT, BE, CH, DE, FR, GB, IT, LI, LU, NL, SE 1. Compounds of formula I wherein: R₁ is a _COOR, nitro or cyano group; R₂ is phenyl or phenyl substituted by one or more halogen atoms, nitro, cyano or C₁-C₆-alkylthio, R₃ is a COOR group; R₄ is a C₁-C₆ alkyl group, substituted by amino, a phenyl group or a group of formula wherein X is a halogen atom and R₅ and R₆, are hydrogen, and R is a C₁-C₄-alkyl group or a C₁-C₄ alkyl group substituted by C₁-C₆-alkoxy, addition salts thereof with pharmaceutically acceptable acids or bases, enantiomers, diastereoisomers or mixtures thereof. 2. Compounds as claimed in claim 1, wherein R₄ is a phenyl, 2-amino-ethyl, isouronium hydrochloride group. 3. Compounds as claimed in claims 1 or 2, wherein R₂ is selected from the group consisting of phenyl, m-nitro-phenyl, o-methylthiophenyl, m-methylthiophenyl, m-chlorophenyl, o-nitrophenyl. 4. As compouds as claimed in claim 1: 2-phenylselenylmethyl-3,5-dicarbomethoxy-4-phenyl-6-methyl-1,4-dihydropyridine; 2-phenylselenylmethyl-3,5-dicarboethoxy-4-(m-chlorophenyl)-6-methyl-1,4-dihydropyridine; 2-phenylselenylmethyl-3-carbomethoxy-4-(m-cyano-phenyl)-5-isopropoxycarbonyl-6-methyl-1,4-dihydropyridine; 2-phenylselenylmethyl-3-carboethoxy-4-(o-nitro-phenyl)-5-methoxy-ethoycarbonyl-6-methyl-1,4-dihydropyridine; 2-phenylselenylmethyl-3-carboethoxy-4-(o-methylthiophenyl)-5-carbomethoxy-6-methyl-1,4-dihydropyridine; 2-phenylselenylmethyl-3,5-dicarbomethoxy-4-(m-methylthiophenyl)-6-methyl-1,4-dihydropyridine; 2-phenylselenylmethyl-3-carboethoxy-4-(m-nitrophenyl)-5-nitro-6-methyl-1,4-dihydropyridine; 2-(2-aminoethyl)selenylmethyl-3,5-dicarbomethoxy-4-(m-nitrophenyl)-6-methyl-1,4-dihydropyridine; 2-(2-aminoethyl)selenylmethyl-3-carboethoxy-4-(o-methylthiophenyl)-5-carbomethoxy-6-methyl-1,4-dihydropyridine; 2-(2-aminoethyl)selenylmethyl-3,5-dicarboethoxy-4-(m-methylthiophenyl)-6-methyl-1,4-dihydropyridine; 2-(-2-aminoethyl)selenylmethyl-3-carbethoxy-4-(m-nitrophenyl)-5-cyano-6-methyl-1,4-dihydropyridine; 2-(2-aminoethyl)selenylmethyl-3-carboethoxy-4-(m-methylthiophenyl)-5-nitro-6-methyl-1,4-dihydropyridine; [(6-methyl-3,5-dicarboethoxy-4-(m-nitrophenyl)-1,4-dihydropyridin-2-yl)methyl]isoselenouronium chloride; [(6-methyl-3-carboethoxy-4-(m-nitrophenyl)-5-carbomethoxy-1,4-dihydropyridin-2-yl)methyl]isoselenouronium chloride; [(6-methyl-3-carboethoxy-4-(o-methylthiophenyl)-5-carbomethoxy-1,4-dihydropyridin-2-yl)methyl]isoselenouronium chloride; [(6-methyl-3,5-dicarboethoxy-4-(m-methylthiophenyl)-1,4-dihydropyridin-2-yl)methyl]isoselenouronium chloride; 2-phenylselenylmethyl-3-carboethoxy-5-carbomethoxy-4-(m-nitrophenyl)-6-methyl-1,4-dihydropyridine; 2(2-aminoethyl-selenylmethyl-3-carboethoxy-5-carbomethoxy-4-(o-methylthiophenyl)-6-methyl-1,4-dihydropyridine. 5. A process for the preparation of compounds of formula I, wherein: R₁ is a _COOR, nitro or cyano group; R₂ is phenyl or phenyl substituted by one or more halogen atoms, nitro, cyano, C₁-C₆-alkylthio, R₃ is a COOR group; R₄ is a C₁-C₆ alkyl group, substituted by amino, a phenyl group or a group of formula wherein X is a halogen atom and R₅ and R₆, are hydrogen, and R is a C₁-C₄-alkyl group or a C₁-C₄-alkyl group substituted by C₁-C₆-alkoxy, addition salts thereof with pharmaceutically acceptable acids or bases, enantiomers, diastereoisomers or mixtures thereof, in which process compounds of general formula II: wherein R₁, R₂ and R₃ have the above mentioned meanings; are reacted with a compound of general formula III: R′₄ Se ⊖ M ⊕ wherein R′₄ has the above defined meanings of R₄, with the exception of an isouronium group of formula (R₅, R₆ and X as above), and M ⊕ is the cation of an alkali or alkaline-earth metal. 6. A process as claimed in claim 5, in which R₄ is an isouronium group, said process consisting in reacting a compound of formula II with a compound of formula V wherein R₅ and R₆, are hydrogen. 7. Pharmaceutical compositions containing as the active ingredient a compound as claimed in claims 1-4, in admixture with a pharmaceutically acceptable carrier. Claims for the Contracting States: ES, GR 1. A process for the preparation of compounds of formula I, wherein: R₁ is a _COOR, nitro or cyano group; R₂ is phenyl or phenyl substituted by one or more halogen atoms, nitro, cyano, C₁-C₆-alkylthio R₃ is a COOR group; R₄ is a C₁-C₆ alkyl group, sustituted by amino, a phenyl group or a group of formula wherein X is a halogen atom and R₅ and R₆, are hydrogen, and R is a C₁-C₄-alkyl group or a C₁-C₄-alkyl group substituted by C₁-C₆-alkoxy, addition salts thereof with pharmaceutically acceptable acids or bases, enantiomers, diastereoisomers or mixtures thereof, in which process compounds of general Formula II: wherein R₁, R₂ and R₃ have the above mentioned meanings; are reacted with a compound of general formula III: R′₄ Se ⊕ M ⊖ wherein R′₄ has the above defined meanings of R₄, with the exception of an isouronium group of formula (R₅, R₆ and X as above), and M ⊕ is the cation of an alkali or alkaline-earth metal. 2. A process as claimed in claim 1, in which R₄ is an isouronium group, said process consisting in reacting a compound of formula II with a compound of formula V wherein R₅ and R₆, are hydrogen.

Inventors: FRIGERIO, MARCO, GANDOLFI, CARMELO A., TOFANETTI, ODOARDO, TOGNELLA, SERGIO
Applicants: BOEHRINGER BIOCHEMIA ROBIN S.P.A.
Application year: 1988
Main classification: C07D211
IPC codes: C07D211