IMIDAZOLYL AND PYRIDYL DERIVATIVES OF PHENYL SUBSTITUTED 1,4-DIHYDRO-PYRIDINES AND PROCESS FOR THEIR PREPARATION

Abstract: Imidazolyl and pyridyl derivatives of phenyl substituted 1,4-dihydropyridines of formula (I), wherein Het is alpha or beta ; A represents a direct linkage, -CH2-, CH2-CH2- or, when Het is alpha , A may also represent -CH=CH-; R is hydrogen, halogen, C1-C3 alkyl or C1-C3 alkoxy; each of R3 and R4 is a C1-C3 alkyl group; one of R1 and R2 is a group -OR' wherein R' is a C1-C6 alkyl either unsubstituted or omega substituted by C1-C3 alkoxy or cyano, and the other is, independently, a) a group -OR'; b) a group psi ; or c) a group -OR<IV> wherein R<IV> is hydrogen or a substituent selected from: (i), (ii), (iii), (iv), are useful as Thromboxane A2 (TxA2) Synthase inhibitors and as calcium antagonists.

Description: IMIDAZOLYL AND PYRIDYL DERIVATIVES OF PHENYL SUBSTITUTED 1,4-DIHYDRO-PYRIDINES AND PROCESS FOR THEIR PREPARATION The present invention relates to imidazolyl and pyridyl derivatives of phenyl substituted 1,4-dihydro- pyridines, to a process for their preparation and to pharmaceutical compositions containing them. The imidazolyl and pyridyl derivatives of the present invention are compounds of the following formula (I) wherein A represents a direct linkage, -CH 2 -, -CH 2 -CH 2 - or- when Het N is may also represent -CH=CH-; R is hyJdrogen, halogen, C.-C- alkyl or C,-C_ alkoxy; each of R_ and R. , which may be the same or different, is a C--C- alkyl group; one of R.. and R_ is a group -OR' wherein R' is C.-Cg alkyl either unsubstituted or omega substituted by C,-C 3 alkoxy or cyano, and the other is, independently, a) a group -OR' as defined hereabove; or R" b) a group -N wherein each of R" and R" ' which may be the same or different, is hydrogen or C.-C-, alkyl; or c) a group -OR wherein R is hydrogen or a substituent selected from the group consisting of (i) -(CH 2 ) m -CH=CH-Ph, wherein m is an integer of 1 to 3 and Ph is a phenyl group either unsubstituted or substituted by one to three substituents chosen among C- * L-C 3 alkyl, C*L-C 3 alkoxy and halogen; RV R V (ii) -Q-N-(CH 2 ) n -OH-Ph wherein Ph is as defined above; Q is a C2-C5 alkylene radical; n is zero, 1 or 2; and each R v is, independently, hydrogen, C1-C3 alkyl or Ph, wherein Ph is as defined above; (iii) -(CH 2 ) m -N N-(CH) n -Ph wherein , n, R v and Ph are as efined above; and (iv) -(CH 2 )p-N X wherein p is 2 or 3 and Ph is as defined above. The invention includes also the pharmaceutically acceptable salts of the compounds of formula (I) as well as all the possible isomers and stereoisomers thereof, and their mixtures. Also the pharmaceutically acceptable bio- precursors (otherwise known as pro-drugs) of the compounds of formula (I) , i.e. compounds which have a different formula to formula (I) above but which nevertheless upon administration to a human being are converted directly or indirectly in vivo into a compound of formula (I) , are included within the scope of the invention. Pharmaceutically acceptable salts of the compounds of formula (I) are, especially, acid addition salts with inorganic, e.g. nitric, hydrochloric, hydrobromic, sulphuric, perchloric and phosphoric, acids, or organic e.g. acetic, propionic, glycolic, lactic, oxalic, malonic, malic, maleic, tartaric, citric, benzoic, cinnamic, mandelic, fumaric, methanesulfonic and salicylic acids. Also the salts of the compounds of formula (I) with pharmaceutically acceptable bases, either inorganic bases, e.g. alkali metal, especially sodium or potassium, or alkaline-earth metal, especially calcium or magnesium hydroxides, or organic bases, e.g. alkyla ines, preferably triethylamine, or basic naturally occurring aminoacids, preferably arginine, as well as the internal salts, i.e. zwitterions, are included within the scope of the present invention. The alkyl and alkylene groups may be branched or straight chain groups. A C j -Cz alkyl group is preferably methyl, ethyl or n-propyl. A C-*.-C 6 alkyl group is preferably a C- -C^ alkyl group, in particular methyl, ethyl, n-propyl, isopropyl or isobutyl. A C- j^ -C β alkoxy group is, preferably, methoxy or ethoxy, particularly methoxy. A C 2 -C 5 alkylene group is, preferably, ethylene, 1,1'-dimethylethylene or a 1,1'- or 2,2'-dimethyl propylene radical. A halogen is, preferably, chlorine, bromine or fluorine, in particular chlorine or fluorine. When the substituent R is other than hydrogen, it is preferably located in position ortho in respect to the carbon atom of the phenyl ring which bears the 1,4-dihydro pyridine substituent. In the group -OR" representing one or both the groups -^ and R 2 , R* is, preferably, unsubstituted C^- 6 SUBSTITUTESHEET alkyl, in particular methyl, ethyl or isopropyl. When one of , it is, preferably, -NH 2 . When one of R-^ and R 2 is a group -OR and R is a substituent as defined above under (i) , (ii) , (iii) or (iv) , the group Ph therein preferably represents a phenyl group either unsubstituted or substituted by C1-C3 alkoxy, in particular methoxy, or halogen, in particular chlorine. When R is a substituent as defined above under (ii) the C2-C5 alkylene Q radical therein is preferably 1,1*-dimethyl ethylene, 1,1'-dimethyl propylene or 2,2'-dimethyl propylene. A representative example of a group-R as defined above under (i) may be the group -CH 2 -CH=CH- ' . R Reepprreesseennttaattiivvee eexxaammpplleess ooff ggroups R as defined above under (ii) may be the following: Representative examples of groups R as defined above under (iii) are the following: X ^)~ Representative example of a group R as defined above under A preferred class of compounds according to the invention are the compounds of formula (I) wherein R is hydrogen, R3 and R 4 are both methyl groups or both ethyl groups, and each of R-^ and R 2 , which may be the same or different, is a group -OR' wherein R' is unsubstituted C^-Cg alkyl, and their pharmaceutically acceptable salts. In the above preferred class the unsubstituted C±- alkyl group representing R' is, preferably, 0*^-04 alkyl, in particular methyl, ethyl or isopropyl. Another preferred class of compounds according to the invention are the compounds of formula (I) wherein: R is hydrogen; R 3 and R 4 are both methyl groups or both ethyl groups; one of R-JL and R 2 is a group -OR' wherein R' is unsubstituted C^-Cg alkyl and the other is, independently. a group -N wherein R" and R" 1 are both hydrogen; or \ R II I a group -OR wherein R is hydrogen or one of the groups (i) and (ii) defined above. and their pharmaceutically acceptable salts. In the above preferred class the unsubstituted C-L-Cg alkyl group for R' is, preferably, unsubstituted 0*^-04 alkyl, in particular methyl, ethyl or isopropyl, and preferred values of the groups (i) and (ii) representing R are those previously indicated as representative examples. When Het in the above formula (I) represents a pyridyl radical—^. 1 , this is preferably substituted by the group A in position 3, that is meta to the pyridine nitrogen. Specific examples of preferred compounds, according to the invention are: 1) 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-1-yl)phenyl]* -3,5-pyridinedicarboxylic acid, dimethyl ester; 2) 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl] • -3,5-pyridinedicarboxylic acid, ethyl methyl ester; 3) 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl] • -3,5-pyridinedicarboxylic acid, diethyl ester; 4) 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl] ■ -3,5-pyridinedicarboxylic acid, isopropyl methyl ester; 5) 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl] • -3,5-pyridinedicarboxylic acid, ethyl isopropyl ester; 6) 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]- -3,5-pyridinedicarboxylic acid, methyl 2-[methyl(phenylmethyl)amino]ethyl ester; 7) 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]- -3,5-pyridinedicarboxylic acid, ethyl 2-[methyl(phenylmethyl)amino]ethyl ester; 8) l,4-dihydro-2,6-dimethyl-4-[2-(lH-imidazol-l-yl)phenyl]- -3,5-pyridinedicarboxylic acid, dimethyl ester; 9) 1,4-dihydro-2,6-dimethyl-4-[2-(lH-imidazol-l-yl)phenyl]- -3,5-pyridinedicarboxylic acid, diethyl ester; 10) 1,4-dihydro-2,6-dimethyl-4-[2-(lH-imidazol-l-yl) henyl]- -3,5-pyridinedicarboxylic acid, ethyl methyl ester; 11) 1,4-dihydro-2,6-dimethyl-4-[2-(lH-imidazol-l-yl)phenyl]- -3,5-pyridinedicarboxylic acid, methyl 2-[methyl(phenylmethyl)amino]ethyl ester; 12) 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl-methyl) phenyl]-3,5-pyridinedicarboxylic acid, dimethyl ester; 13) l,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl-methyl) phenyl]-3,5-pyridinedicarboxylic acid, diethyl ester; 14) 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-1-yl-methyl) phenyl]-3,5-pyridinedicarboxylic acid, isopropyl methyl ester; 15) 1, -dihydro-2,6-dimethyl-4-[3-(lH-imidazol-1-yl-methyl) phenyl]-3,5-pyridinedicarboxylic acid, methyl 2-[methyl (phenylmethyl)amino]ethyl ester; 16) l,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-1-yl-methyl) phenyl]-3,5-pyridinedicarboxylic acid, ethyl 2-[methyl (phenylmethyl)amino]ethyl ester; 17) 1,4-dihydro-2,6-dimethyl-4-[2-(lH-imidazol-1-yl-methyl) phenyl]-3,5-pyridinedicarboxylic acid, dimethyl ester; 18) l,4-dihydro-2,6-dimethyl-4-[3-(2-(lH-imidazol-l-yl) ethenyl)phenyl]-3,5-pyridinedicarboxylic acid, ethyl methyl ester; 19) 1,4-dihydro-2,6-dimethyl-4-[3-(2-(lH-imidazol-l-yl) ethenyl)phenyl]-3,5-pyridinedicarboxylic acid, diethyl ester; 20) l,4-dihydro-2,6-dimethyl-4-[3-(2-(lH-imidazol-l-yl) ethenyl)phenyl]-3,5-pyridinedicarboxylic acid, methyl 2-[methyl(phenylmethyl)amino]ethyl ester; 21) 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]- -3,5-pyridinedicarboxylic acid, ethyl ester; 22) 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl] ■ -3,5-pyridinedicarboxylic acid, 5-amide 3-ethyl ester; 23) 1, -dihydro-2,6-dimethyl-4-[3-(lH-imidazol-1-yl-methyl) phenyl]-3,5-pyridinedicarboxylic acid, ethyl ester; 24) 1,4-dihydro-2,6-dimethyl-4-[3-(2-(lH-imidazol-l-yl) ethenyl)phenyl]-3,5-pyridinedicarboxylic acid, ethyl ester; 25) 1, -dihydro-2,6-dimethyl-4-[3-(3-pyridyl)phenyl]- -3,5-pyridinedicarboxylic acid, isobutyl methyl ester; 26) 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl) henyl]- -3,5-pyridinedicarboxylic acid, diethyl ester; 27) 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl)phenyl]- -3,5-pyridinedicarboxylic acid, diisobutyl ester; 28) 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl)phenyl]- -3,5-pyridinedicarboxylic acid, ethyl ester; 29) 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl)phenyl]- -3,5-pyridinedicarboxylic acid, 5-amide-3-ethyl ester; 30) 1,4-dihydro-2,6-dimethy1-4-[3-(3-pyridyl)phenyl]- -3,5-pyridinedicarboxylic acid, ethyl 2-[methyl (phenylmethyl)amino] ethyl ester; 31) 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl)phenyl]- -3,5-pyridinedicarboxylic acid, isobutyl 2-[methyl (phenylmethyl)amino]ethyl ester; 32) 1,4-dihydro-2,6-dimethyl-4-[4-(3-pyridyl)phenyl]- -3,5-pyridinedicarboxylic acid, diethyl ester; 33) 1,4-dihydro-2,6-dimethy1-4-[4-(3-pyridyl)phenyl]- -3,5-pyridinedicarboxylic acid, ethyl ester; 34) 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl-methyl)phenyl] -3,5-pyridinedicarboxylic acid, diethyl ester; 35) 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl-methyl)phenyl] -3,5-pyridinedicarboxylic acid, ethyl ester; The structural formulae of the compounds listed above, according to their progressive number, are reported in the following Table 1 which refers to compounds of formula (I) wherein R is hydrogen and R 3 and R4 are both methyl groups. TABLE 1 TABLE 1 fContd. TABLE 1 (Contd) The compounds of the invention can be prepared by a process comprising: a) reacting a compound of formula (II) wherein R, A, Het, R2 and R 3 are as defined above, but R 2 is different from -OH, with a compound of formula (III) wherein R*L and R4 are as defined above, but R^ is different from -OH, thus obtaining a compound of formula (I) wherein R, A, Het, R-^, R 2 , R 3 and R 4 are as defined above, with the exception of a compound of formula (I) wherein one of R-^ and R 2 is -OH; or b) reacting a compound of formula (II) with a compound of formula (IV) CH 2 -C0R 1 (IV) 0=C wherein R-L and R are as defined above, but R* * L is different from -OH, in the presence of an ammonium salt or hydroxide, thus obtaining a compound of formula (I) wherein R, A, Het, R-^, R 2 , R 3 and R 4 are as defined above, with the exception of a compound of formula (I) wherein one of R^ and R 2 is -OH; or c) reacting a compound of formula (V) wherein R, A and Het are as defined above, with a compound of formula (III) and a compound of formula (IV) together, thus obtaining a compound of formula (I) wherein R, A, Het, R l ' R 2' R 3 and R 4 are defined above, with the exception of a compound of formula (I) wherein one of l and R 2 is -OH; or d) reacting a compound of formula (V) with a compound of formula (IV) wherein R^ is a group -OR' as defined above in the presence of an ammonium salt or hydroxide, thus obtaining a compound of formula (I) wherein R, A, Het, R 3 and R 4 are as defined above and each of R-^ and R is a group -OR' wherein R' is as defined above, and wherein R-^ is equal to R 2 and R 3 is equal to R 4 ; or e) transforming a compound of formula (I) wherein one of R*L and R 2 is different from -OH into a corresponding compound of formula (I) wherein one of R*L and R 2 is -OH; and, if desired, converting a compound of formula (I) into another compound of formula (I) , and/or, if desired, converting a compound of formula (I) into a pharmaceutically acceptable salt thereof, and/or, if desired, converting a salt into a free compound, and/or, if desired, separating a mixture of isomers of formula (I) into the single isomers. The reactions described above under a) , b) , c) , d) , and e) can be performed by using known methods of the organic chemistry and, particularly, those typical of the chemistry of 1,4-dihydro-pyridines, such as those described e.g. by U. Eisner and J. Kuthan in Chem. Rev. 22, 1 (1972) and by D.M. Stout and A.I. Meyers in Chem. Rev. .82., 223, (1982) . In particular, reactions such as those described under a) , b) , c) and d) may be carried out following the same basic procedure, e.g. by heating the reactants at a temperature ranging from about 50°C to about 150°C in a suitable inert organic solvent such as, e.g. methanol, ethanol, isopropanol, dioxane, tetrahydrofuran, dimethylformamide, acetonitrile, dimethylsulfoxide, pyridine or their mixtures. The ammonium hydroxide used in processes b) and d) may be, for example, in the form of concentrated aqueous ammonia, while an ammonium salt may be, for instance, ammonium acetate. The transformation of process variant e) may be, for example, an acidic or alkaline hydrolysis of a compound of formula (I) wherein one of the COR^ and COR 2 groups is a suitable labile ester group such as, e.g. a cyanoethyl or tert-butyl ester, the hydrolysis being performed, preferably at room temperature, following the usual procedures. Optional conversions of a compound of formula (I) into another include, e.g. the following: A compound of formula (I) containing a free carboxy group, may be converted into a compound of formula (I) containing an esterified carboxy group by esterification, e.g. via the corresponding acid halide, e.g. chloride, or reacting it with an excess of suitable aliphatic alcohol, or by direct esterification by means of acidic catalysis i.e. in the presence of dry HCl or S0C1 2 or BF 3 -etherate. A compound of formula (I) containing a free or esterified carboxy group may be converted in a compound of formula (I) containing a -CON R ' group, wherein R' and R" are as defined above, according to known methods. For example, the conversion of an esterified carboxy group into the corresponding amide may be performed by direct reaction with ammonia or an appropriate amine in a suitable solvent, e.g. ether or benzene or using an excess of the amine as solvent, at temperatures ranging from room temperature to reflux. The conversion of a free carboxy group into the corresponding amides may be carried out via an intermediate reactive derivative which may be isolated or not. Intermediate reactive derivatives may be active esters e.g. N0 2 -phenyl esters, or N-hydroxysuccinimide esters, acid halides, preferably chloride, mixed anhydrides e.g. ethoxycarbonyl or tert-butylcarbonyl anhydrides, or the reactive intermediates obtained in situ by reaction of the acid with dicyclohexylcarbodiimide or carbonyldiimidazole. The reactive intermediates, obtained following conventional ways, as those usually employed in the synthesis of peptides, are reacted with ammonia or an appropriate amine in a suitable solvent or with an excess of the amine itself at temperatures ranging preferably from about -10"C to about 50 β C. The optional salification of a compound of formula (I) as well as the conversion of a salt into the free compound and the separation of a mixture of isomers into the single isomers may be carried out by conventional methods. For example the separation of a mixture of geometric isomers, e.g. cis- and trans- isomers, may be carried out by fractional crystallization from a suitable solvent or by chromatography, either column chromatography or high pressure liquid chromatography. Compounds of formula (II) may be prepared by reacting a compound of formula (V) with a compound of formula (IV) following the well known procedure for the Knoevenagel reaction, such as, e.g. described by G.Jones in Org. Reactions, .15 (1967) pp. 204-599. Of course the meanings of R-^ and, respectively, R in the compound (IV) must be those wanted for R and, respectively, R3 in the compound (II) . The process is preferably carried out by reacting compounds (IV) and (V) in the presence of a suitable base, e.g. diethylamine or pyridine, in a suitable solvent, e.g. ethanol or benzene, at temperatures ranging approximately from room temperature to the reflux. Compounds of formula (III) and (IV) are known compounds or may be prepared following usual procedures from known compounds. Compounds of formula (V) are known compounds too or may be prepared by known methods from known compounds e.g. by reducing the corresponding alkyl esters of formula (VI) wherein R, A and Het are as defined above and R VI is C -C β alkyl. The reduction may be performed in the presence of a suitable reducing agent as, e.g., diisobutylaluminium hydride in a suitable solvent such as, e.g., diethylether or tetrahydro- furan, at temperatures ranging from about -80°C to the room temperature. Alternatively, compounds of formula (V) may be prepared by oxidation of the corresponding alcohol of formula (VII) CH.OH wherein 2 R, A and Het are as defined above. The process of oxidation may be performed following well known procedures for converting a primary alcohol to the corresponding aldehyde, e.g. those described by J.March in Advanced Organic Chemistry 1985, J.Wiley Publ. , p.1057-1060. Moreover compounds of formula (V) wherein A is a direct linkage, may be prepared by oxidation of compounds of formula (VIII) CH 3 wherein R and Het are as defined above. The process of oxidation may be performed following known procedure, e.g. by use of chromic anhydride in acetic anhy¬ dride. Compoundsof formulae VI, VII and VIII are known compounds or may be prepared following known procedures, e.g.those repor¬ ted in J.Med.Che . (1981) 24, 1475 or in J.Med.Chem. (1981), J24_, 1149 or in the European Patent Application 173172 A2. In particular compounds of formulae (VI) and (VII) wherein Het is the imidazolyl radical may be prepared, for example, by reacting imidazole or a salt thereof, e.g. the sodium salt, with, respectively, " compounds of formula (IX) or of formula (X) wherein R, A and R VI are as defined above and X is a suitable leaving group, such as, for example, a suitable halogen, preferably chlorine or bromine, or a tosyl or a mesyl group, following experimental procedures well known from the chemical literature. Compounds (IX) and (X) are known compounds. The compounds of formula (I) of the present invention show, principally, inhibitory activity of Thromboxane TxA 2 Synthase and Calcium antagonistic activity. Their ability to inhibit TxA 2 Synthase activity (as reflected by TxB 2 generated in whole blood during clotting or in isolated glomeruli) was tested in vitro and ex vivo in the rat. The in vitro experiments were carried out as follows: The effect of the compounds on TxA synthesis was evaluated in serum and in glomeruli isolated from kidney cortex of reduced renal mass rats (RRM) . Ablation of >70% of renal mass in the rat results in hypertension, proteinuria and glomerular sclerosis of the remnant kidney. Rats with a remnant kidney have increased excretion of thromboxane in the urine when compared with normal rats [Purkerson et al.-Proc.Natl.Acad.Sci.USA 82., 193, 1985]. Blood was withdrawn from the abdominal aorta of the animals under light ether anesthesia. The blood was immediately divided in portions of 0.5 ml and distributed in glass tubes each containing a concentration of the test compounds or of the reference compounds, i.e. Dazoxiben, which is thromboxane synthase inhibitor [Randall et al.-Thromb.Res. 23. 145, 1981] and Acetylsalicylic acid (ASA), which is cyclooxygenase inhibitor. Samples were then allowed to clot for 1 h at 37°C, centrifuged at 3000 rpm for 10 min, serum collected and stored at -20°C until assayed. TxB 2 levels were determined by RIA according to previously described procedures [Patrono et al.-Thromb.Res. 17, 3/4, 317, 1980] using highly specific antibody. The isolation of glomeruli was performed as previously described [Patrignani et al., -J.Pharm. Exp. Ther. 228. 2, 472, 1984]. The isolated glomeruli of 4 rats were pooled, suspended in modified Krebs buffer (pH 7.3) and divided into portions of 1 ml each containing a concentration of the test compounds or of the reference compounds. The TxA 2 synthesis was induced by incubating the glomeruli under shaking at 37 β C for 1 h. At that time the incubation was stopped by centrifugation at +4°C, the supernatant collected and stored at -20°C until assayed by RIA. The ex vivo experiments were performed as follows. The compounds were orally administered to RRM rats by gavage at the dose of 2.5 mg/kg in 0.5% methocel. One hour after treatment rats were anaesthetised with ether, blood was withdrawn from the abdominal aorta and allowed to clot for 1 h at 37°C. Samples were then centrifuged, serum collected and stored at -20°C until assayed. The compounds of the invention showed remarkable activity in both the in vitro and the ex vivo tests. In particular, for example, the compounds of the invention 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)-phenyl]- -3,5-pyridine dicarboxylic acid,diethyl ester (internal code FCE 24265) and 1,4-dihydro-2,6-dimethγl-4-(3-(3-pyridyl) henyl)-3,5-pyridi- ne dicarboxylic acid,diethyl ester (internal code FCE 26055) were found to exhibit a marked inhibitory activity on TxA 2 synthesis in whole blood being 7 and, respectively, 3 times more potent than the reference compound Dazoxiben, and being 247 and, respectively, 90 times more potent than the re¬ ference compound ASA. The results are summarized in Table 1. Table 1: In vitro effect on TxB 2 synthesis in RRM rats whole blood. Data are expressed as IC so (M) and limits for P=0.95 Moreover the compounds of the invention were also active in inhibiting glomerular TxB_. production. In particular, for example, the compound 1,4-dihydro-2,6- dimethyl-4-[3-(lH-imidazol-l-yl)-phenyl]-3,5-pyridinedicar¬ boxylic acid, diethyl ester (FCE 24265) was shown to be 4.7 and, approximately, 4,000 times more potent than Dazoxiben and ASA, respectively, on glomerular TxB 2 synthesis. These results are summarized in Table 2. Table 2:In vitro effect on TxB 2 synthesis in RRM rats glome¬ ruli. Data are expressed as IC 50 (M) and limits for P=0.95 In the ex vivo test in the rat the same compound FCE 24265 was found to inhibit the synthesis of TxA 2 with an ED_. 0 value of 2.3 mg/kg p.o. The Calcium antagonistic activity of the compounds of the invention was tested by evaluating their effect on the response of the isolated guinea pig ileum to contractions of K " " in vitro. The terminal ileum of albine male guinea pigs (250-300 b.w) was immediately removed when the animal were killed, washed and maintained in a 10 ml organ bath containing Tyrode's solution gassed with 95% 0 2 and 5% C0 2 and thermoregulated at 37°C. The tissue was preloaded with 1 g and contractions were recorded by a Basile DY1 isometric transducer on a Watanabe Mark V recorder. Contractions to K " "60 mM were obtained at a 15 min intervals in absence and presence of increasing concentrations of test compounds. The antagonists potencies were expressed as IC so values, i.e. the molar concentration of antagonist which inhibits K" " response by 50%. The compounds of formula (I) showed remarkeble activity also in this test. For example, in particular, the compounds of the invention l,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l- -yl)-phenyl]-3,5-pyridine dicarboxylic acid, diethyl ester (FCE 24265), 1,4-dihydro-2,6-dimethyl-4-(3-(3-pyridyl) phenyl)-3,5-pyridine dicarboxylic acid (2-(N-benzyl-methyl- amino)ethyl)-ethyl ester (FCE 26225) and 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl)phenyl]-3,5-pγridi- ne dicarboxylic acid,diethyl ester (FCE 26055) at concentra¬ tions from 3x10 -β M to 1x10 -s M were found to inhibit dose- dependently ^contractions with IC so value of 6.2xl0 ~β M, 6.4xl0 _β M and l.lxlO -"7 M respectively. The compounds of the invention, being able to inhibit selec tively the formation of TxA 2 ,can be used as vasodilatory an antiaggregant agents, for example in all the cases of throm bosis, periferal vasculopaties and coronary artery disease In fact inhibition of TxA 2 production reduces th probability of thrombi formation and of vasoconstrictio with consequent ischemic events and, leaving unaltered (or increasing) PGI 2 production, improves vasodilation, tissu blood supplies and protects the vessel wall. Another use of the compounds of the invention is for th treatment of migraine. As is known, for example, in the cas of migraine it has been demonstrated a diffused vasocon- striction induced by platelet TxA 2 overproduction [J.ciin. Pathol.(1971), 24, 250; J. Headache (1977) 17, 101]. A platelet overproduction of TxA 2 and MDA (malondialdehyde in diabetes mellitus has been demonstrated and correlate with microcirculatory defects in the illness [Metabolism (1979) 2£, 394; Eu.J.Clin.Invest. (1979) 9_, 223; Thrombosi Haemost. (1979), 42, 983; J.Lab.Clin.Med. (1981) 9_7, 87]. Therefore, the compounds of the invention can be used, e.g. in the treatment of diabetic microangiopathy. Moreover, the compounds of the invention can be used as anti-inflammatory agents. As is known, for example, flui obtained from carrageenin-induced granuloma convert arachidonic acid into TxA 2 in vitro and TxA 2 levels are increased in the synovial fluid of rheumatoid arthritis patients and in the fluid of carrageenin-induced inflamma¬ tion in rats [Prostaglandins (1977),13, 17; Scand. J.Rheum. (1977), 6_ 1511. Moreover the compounds of the invention can be used as hypotensive agents. Recently it has been in fact demonstrated that an overproduction of TxA 2 is involved in the pathogenesis of hypertension and that a specific inhibitor of TxA 2 produc- tion may be employed in hypertension [Eu.J.Pharmacol. (1981) , 7_0, 247]. An increased TxA 2 synthesis and decreased prostacyclin synthesis are also reported in pregnancy-induced hyperten¬ sion [Am.J.ObstetrGynecol. (1987), 157, 325; Hypertension (1988), 11 r 550]. Treatment with thromboxane synthase inhibitors is therefore useful in this pathology. The antihypertensive activity of the compounds of the inven¬ tion was tested in chronically cannulated hypertensive rats (SHR) . For intra-arterial measurements of blood pressure (MBP) catheters (PE50 Clay Adams) were implanted in the right carotid artery under alothane anesthesia. Two days after surgery the animals were placed in a Ballman cage and the arterial catheter was connected to a stathman P23 Db pres- sure transducer and a Beckman multichannel R611 BP recor¬ der for continuous monitoring of MBP and heart rate (HR) . Measurements were made predrug and 0.5, 1, 2, 4, 6 h after drug or vehicle (methocel 0.5% w/v) . In the above test the compounds of the invention were found to be active. For example, the compound of the invention FCE 24265 exhibited a marked antihypertensive activity with a rapid onset, the peak effect (-30 ± 4 mm Hg) being reached at 30 minutes postdrug. Blood pressure returned toward normal levels 3 hours after treatment. No changes in heart rate were observed. Furthermore it has been shown a role of TxA 2 in the pathogenesis of ulcerative disorders of the stomach in accordance with its powerful gastric vasoconstrictory activity, so that also in this field a TxA 2 inhibitor is useful [Nature (1981), 202. 472]. In fact the compounds of the invention are indicated for the treatment of peptic ulcers. The compounds of the invention can be also antitumoral agents. It is known, for example, that a selective inhibition of TxA 2 synthesis has been demonstrated to reduce the number of lung metastases and to slow down tumor growth [Nature (1982), 295. 188]. In view of the correlation between TxA 2 synthesis and calcium transport, recently showed by some authors, specific TxA 2 synthetase inhibitors, such as the compounds of the invention, can also find use in the treatment of osteoporosis, e.g. post-menopausal osteoporosis [Prostaglandins (1981), 21 , 401]. Moreover the compounds of the invention are indicated for the treatment of angina pectoris. In this respect, it is known, for example, that high levels of TxB 2 have been found in patients with Prinz- metal's angina [Prostaglandins and Med. (1979), 2., 243] and in patients with recurrent angina attacks [Sixth Intern. Congress on Thrombosis, Monte Carlo October. 1980 Abs N°140]. The platelet antiaggregatory activity of the compounds of the invention was evaluated in vitro and in vivo, for example, according to the modified methods of Born [Born G.V.R. , Nature 194. 927 (1962)] and Silver [Silver M.J., Science 183. 1085 (1974)]. The compounds of this invention were found in vitro to have inhibitory activity on platelet aggregation induced by collagen in human platelet rich plasma. Therefore the compounds of the invention may be useful in preventing or reducing platelet loss during extracorporeal circulation; for example during coronary artery by-pass and graft procedures or during kidney dialysis. It has been moreover shown that circulatory shock, for example endotoxic and haemorragic shock, is associated with increased TxA 2 synthesis so that the compounds of the invention can be useful in these pathologies. Moreover, the compounds of the present invention can also be useful for the treatment of bronchial hyperreactivity in the therapy of asthma. A role for TxA 2 in asthma can be inferred on the basis of its bronchoconstrictory activity in experimental animal models [Br. J. Pharmacol. (1984), £2. (3) 565]. An inhibitory activity of bronchospasm induced by Platelet Activating Factor (PAF) in rats is also reported, e.g. for the TxA synthetase inhibitors described in British Patent NO.2205494. The compounds of the present invention can also find use in the treatment of nephropathies, e.g. forms of glomerulonephritis, diabetic nephropathy or nephropathies secondary to systemic lupus erithematous (SLE) , and in the prevention and/or treatment of Cyclosporin A- induced nephrosis. Recently a positive correlation between enhanced intra-renal synthesis of TxA 2 and the progression of chronic glomerular disease has been demonstrated in different animal models of immune and non-immune renal damage and in humans [J. Clin. Invest. (1985) 5 94; J.Clin. Invest. (1985), 76, 1011]. The compounds of the invention may be also used to inhibit the renal and cardiac transplant rejection. In fact after transplantation increased urinary TxB 2 excretion or whole blood TxA 2 synthesis have been reported both in SUBSTITUTESHEET man and rats [Lancet (1981) , ii, 431; Transplantation (1987) 43., 346]. Another use of the compounds of the present invention is in the treatment of hyperlipidaemia, namely hypercholesterolaemia and hypertriglyceridaemia secondary to nephrotic syndrome. Hyperlipidaemia is a common feature of nephrotic syndrome in man [New Engl. J. Med. (1983) 312 (24) 1544] and in addition elevated triglycerides and cholesterol levels are reported in animal models such as doxorubicin induced nephrotic syndrome [Expt. Mol. Pathology (1983) , 39. 282]; elevated urinary albumin excretion has been suggested as the pathogenetic mechanism [Kidney international (1987), 3_2., 813]. It has also been shown that in cholesterol fed rabbit, an animal model of diet induced atherosclerosis, arachidonic acid metabolism is an important factor in early lesion development. In particular a shift in metabolism from TxA 2 to PGE 2 may suppress lesion development (i.e. atheromatous plaque) in hypercholesterolaemia. The compounds of the invention can also be used in association with thrombolytic agents (e.g. tPA, Streptokinase, pro-ϋrokinase) in order to reduce the dose of the latter required in thrombolytic therapy, and to lower the incidence of reocclusion and possibly haemorrhage. Furthermore, in view of their Calcium antagonistic activit (slow inward Calcium channel blockers; Calcium entr blockers), by reducing the Calcium influx across th membrane of the excitable heart muscle cells or the coronar and systemic arterial smooth muscle cells, the compounds o the invention may be useful to control the myocardial coronary and peripheral arterial contractility. Due to this activity their use in the treatment o hypertension,angina,tachicardias and myocardial arrhythmias cerebral ischemia and migraine is further supported Moreover, acting on the Calcium accumulation in the arteria vessel wall occurring in the development of the atheroma and also in view of their platelet aggregation inhibitor effect,they may have useful application as antiatherosclero tic agents. More particularly, due to the dual activity as TxA 2 Synthas inhibitors and Calcium-antagonists, the compounds of the invention may exert a synergistic beneficial effect in those pathological conditions, in which the vasoconstriction is the results of multiple mechanism and is associated with " enhanced TxA 2 biosynthesis. Thus the compounds of the invention can be particularly useful in the prevention and in the treatment of pathologies such as, for example, hypertension, unstable angina, cerebral ischemia, migraine, progressive glomerulosclerosis and atherosclerosis. The toxicity of the compounds of the invention is negligible, so that they can be safely used in therapy. Mice and rats which had been deprived of food for nine hours were treated orally with single administrations of increas¬ ing doses of compounds of the invention, then housed and normally fed. For example the orientative acute toxicity (LD so ) of the compound FCE 24265, assessed on the seventh day after treatment, was higher than 800 mg/kg. In view of their high therapeutic index the compounds of the invention can be safely used in medicine. The therapeutic regimen for the different clinical syndromes must be adapted to the type of pathology taking into account, as usual, also the route of administration, the form in which the compound is administered and the age, weight and conditions of the subject involved. The oral route is suitable, in general, for all conditions re¬ quiring such compounds. Preference is given to intravenous injection or infusion for the treatment of acute pathological states. For maintenance regimens the oral or parenteral, e.g. intra¬ muscular, route is preferred. The dosage level suitable for oral administration to adult humans of the compounds of the invention, e.g. of 1 ,4-dihydro-2, -dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3,5-pyridine dicar- boxylic acid, diethyl ester and 1,4-dihydro-2,6-dimethy1-4- -j3-(3-pyridyl)phenyl]-3,5-pyridine dicarboxylic acid, diethyl ester may range from about 5 mg to about 500 mg per dose 1 to times a day, preferably from about 20 mg to about 150 mg per dose 1 to 3 times a day. Of course, these dosage regimens may be adjusted to provide the optimal therapeutic response. As already said, the present invention includes in its scope also the pharmaceutical compositions containing the compounds of formula (I) in association with pharmaceutically acceptable carriers or diluents. The nature of the pharmaceutical compositions will, of course, depend upon the desired route of administration. The compositions may be formulated in the conventional manner with the usual ingredients. For example, the compounds of the invention may be administered in the form of aqueous or oily solutions or suspensions, tablets, pills, "capsules, syrups, drops or suppositories. Thus, for oral administration, the pharmaceutical compositions containing the compounds of this invention are preferably sugar or film coated tablets, pills or gelatine capsules which contain the active substance together with diluents, such as lactose, dextrose, sucrose, annitol, sorbltol, cellulose; lubricants, for instance silica, talc, stearic acid, magnesium or calcium stearate, and/or polyethylene glycols; or they may also contain binders, such as starches, gelatine, methylcellu- lose, carboxymethylcellulose, gum-arabic, tragacanth, polyvinyl- pirrolidone; disaggregating agents, such as -starches, alginic acid, alginates, sodium starch glycolate; effervescing mixtures; dyestuffs; sweeteners; wetting agents, such as lecithin, poly- sorbates, laurylsulphates; and, in general, non-toxic and pharma¬ cologically inactive substances used in pharmaceutical formula¬ tions. Said pharmaceutical preparations nay be manufactured in known manner, for example by means of aixing, granulating, tabletting, sugar-coating, or film-coating processes. The liquid dispersions for oral administration eay be, e.g., syrups, emulsions and suspensions. The syrups may contain as carrier, for example, saccharose or saccharose with glycerine and/or mannitol and/or sorbitol. The suspensions and the emulsions may contain as carrier, for example, a natural gum, agar, sodium alginate, pectin, nethylcellulose, carboxymethylcellulose, or polyvinyl al¬ cohol . The suspensions or solutions for intramuscular injections may contain together with the active compound a pharmaceutically acceptable carrier, e.g. sterile water, olive oil, ethyl oleate, glycols, e.g. propylene glycol, and if desired, a suitable amount of lidocaine hydrochloride. The solutions for intravenous injection or infusion may contain as a carrier, for example, sterile water or, preferably, they may be in the form of sterile aqueous isotonic saline solutions. The suppositories may contain, together with the active compound, a pharmaceutically acceptable carrier e.g. cocoa-butter, polyethylene glycol, a polyoxyethylene sorbitan fatty acid ester surfactant or lecithin. In this specification the abbreviations "OMe", "OEt", "OiPr", "Et 2 0", "AcOH" stand, respectively , for "methoxy", "ethoxy", "isopropoxy", "diethyl ether", "acetic acid". The following examples illustrate but do not limit the present invention. - 35 - Example 1 A mixture of 17.2 g (0.1 mol) of 3-(lH-imidazol-l-yl)- benzaldehyde, 26 g (0.2 mol) of ethyl .acetoacetate and 5 ml of concentrated NH 4 . OH in absolute ethanol (25 ml) was refluxed for 6 hours. The mixture was poured into 500 ml of ice-water and the aqueous solution was extracted with methylene chloride. The organic layers were put together, dried over CaCl_ and evaporated under vacuum. The crude product was recrystallized from Et 0, giving 25.7 g (65#) of l,4-dihydro-2,6-dimethyl-4- 3-(lH-imidazol-l-yl)phenyl]- -3,5-pyridinedicarboxylic acid, diethyl ester, m.p.202-20 β C; Elemental analysis: Found: C 66.83; H 6.38; N 10.62 Calculated for C 22 H 2 5 N 3 ° 4 : C 66 * 81 '« H 6.3 7 ; N 10.62 TLC: eluant CHC1 /CH OH/AcOH « 90/10/1,R f » 0.53 N.M.R. (CDC1 ) p.p.m. : 1.23 (6H,t,CH CH ) 2.38 (6H,s,*C-Cji ) 4.12 (4H,q,CH 2 CH 3 ) 5.08 (lH,s,CH at 4 position of dihydropyridine) 6.27 (lH.br s.NH) 7.1-7.4 (6H,m,phenylic + CH=CH imidazolic protons) 7.82 (lH.br s,N-CH-N). The intermediate 3-(lH-imidazol-l-yl)-benzaldehyde was prepa- red by reducing with diisobutylaluminium hydride the correspon¬ ding ethyl ester (m.p. 76-78 « C,from Et 0), obtained in turn from the free corresponding benzoic acid. The latter, namely 3-(lH-imidazol-l-yl ) -benzoic acid, was obtained from 3-bromobenzoic acid by reaction with imidazole in refluxing* nitrobenzene, in the presence of K2_ . C03_. and CuBr. By proceeding analogously the following compounds may be 5 prepared: l,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-1-yl-methy1)phenyl] -3,5-pyridinedicarboxylic acid, diethyl ester, m.p. 196-199°C; Elemental analysis: Found: C 67.15; H 6.64; N 10.11 10 Calculated for C H N 0 4 : C 67.46; H 6.65; N 10.26 TLC: eluant CHC1 /CH OH = 92/B.R = 0.57 N.M.R. (CDC1 ) p.p.m. : 1.21 (6H,t,CH_CH_ ) 2.30 (6H,s,=C-CH 3 ) 15 4.08 (4H,q,CH CH ) 4 .98 (lH.s.CH at position of dihydropyridine) 5.09 (2H.S.-C-CH -N ) 5.77 (1H.S.NH ) 6.8-7.7 ( 7H,m,phenylic ♦ CH=CH imidazolic protons ) 20 1 , 4 -dihydro-2, 6-dimethy 1-4- [3- (lH-i i dazol-1-yl) phenyl] -3,5- -pyridinedicarboxylic acid, dimethyl ester, m.p. 212-216°C; Elemental analysis: Found: C 65.11; H 5.78; N 11.31 Calculated for c 20 H 2 ι N 3° 4 : C 6S - 38' ' H 5- 7 6ϊ N 11-44 25 TLC: eluant CHC1 /CH..OH = 95/5 R f = 0.28 N.M.R. (CDC1»)£ p.p.m. : 2.43 (6H,S,=C-CH 3 ) 3.71 (6H,s,C00CH 3 ) 5.17 (lH.s.CH at 4 position of dihydropyridine) 30 5.80 (lH.s.NH) 7 .1-7.5 ( 6H,rn. henyl ic + CH=CH imidazolic protons) 7 .9 (lH.br s.N-CH-N); 1,4-dihydro-2,6-dimethy1-4-[2-(lH-imidazol-l-yl)phenyl]- •3.5-pyridinedicarboxylic acid, diethyl ester, m.p. 208-210°C; Elemental analysis: Calculated for C 2 2 H 25 N 3°4 : C 66.81; H 6.31; N 10.62 Found C 66.12; H 6.30; N 10.50 T.L.C. : eluant CHC1 3 CH 3 0H « 90/10, Rf « 0.57; 1,4-dihydro-2,6-diethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3,5- -pyridinedicarboxylic acid, diethyl ester, m.p. 171-172°C; Elemental analysis: Calculated for C p4 H 2g N 3 0 4 : c 68.06;H 6.90..N 9.92 Found C 67.80; H 6.90; N 9.81 T.L.C. : eluant CHCl /CH OH = 180/20, Rf = 0.66 N.M.R. (CDC1 ) S p.p.m. : 1.21 (l2H,m,2 CO CH CH + 2=C-CH CH ) 2.88 (2H,dq,2=C-CH H CH ) 4.10 (4H,m,2 CO CH CH ) 5.06 (lH,s,CH at 4 position of dihydropyridine) 6.12 (lH.bs.NH) 7.10-7.40 (6H,m,CH at 2,4,5,6 positions of phenyl ring and CH at 4,5 positions of imidazole) 7.95 (lH.s.CH at 2 position of imidazole),- 1 , 4-dihydro-2 , 6-dimethyl-4- [2-methyl-5- ( iπιidazol-1-yl ) phenyl] -3, 5-pyridinedicarboxylic acid, diethyl ester, Elemental analysis : Found: C 65.97; H 6.58; N 10.08; Calculated for C 2 3 H 27 N 3°4 : C 67.46; H 6.65; N 10.26 1.23 (6H,t,2C0 2 CH 2 CH 3 ) 2.37 (6H.S.2 =C-CH ) 2.66 (3H,s,CH at 2 position of phenyl ring) 4.14 (4H,q,2C0 2 CH 2 CH 3 ) 5.22 (1H,S,CH at 4 position of dihydropyridine) 6.36 (lH,s,NH) 7.00-7.50 (5H,m,CH at 3,4,6 positions of phenyl ring and at 4,5 positions of imidazole) 8.15 (lH.s.CH at 2 position of imidazole) MS : m/z 409 M + ; 1,4-dihydro-2,6-dimethyl-4- - luoro-3-(imidazol-1-yl)phenyl] -3,5-pyridinedicarboxylic acid, diethyl ester; l,4-dihydro-2,6-dimethyl-4-[2-(lH-imidazol-l-yl)phenyl]- 3,5-pyridinedicarboxylic acid, dimethyl ester; l,4-dihydro-2,6-dimethyl-4-[3- (lH-imidazol-1-yl-methyl) phenyl]-3,5-pyridinedicarboxylic acid, dimethyl ester; l,4-dihydro-2,6- methyl-4-[2-(lH-imidazol-1-yl-methyl) phenyl]-3, 5-pyridinedicarboxylic acid, dimethyl ester; and l,4-dihydro-2,6-dimethyl-4-.3- (2-(lH-imidazol-l-yl)ethenyl) phenyl]-3,5-pyridinedicarboxylic acid, diethyl ester. Example 2 A mixture of 0.27 g (1.56 mmol) of 3-(lH-imidazol-l-yl)- benzaldehyde, 0.204 g (1.56 mmol) of ethyl acetoacetate and 0.18 g (1.56 mmol) of me hyl-3-aminocrotonate in absolute ethanol (10 ml) was refluxed for 6 hours. The mixture was poured into 20 ml of ice-water and the aqueous solution was extracted with methylene chloride. The organic layers were put together, dried over CaCl. and eva¬ porated under vacuum. The crude product was purified over flash silica-gel column (ethyl acetate:n-hexane*sl:4).giving 0.3 (60%) of 1, -dihydro-2,6-dimeth 1-4-[3-(IH-imidazol-1-yl)phenyl -3,5-pyridinedicarboxylic acid, ethyl methyl ester,m.p.l97-200 β Elemental analysis: Found: C 65.57; H 6.20; N 10.79 Calculated for C H N n : c 66.13; H 6.08; N 11.02 TLC: eluant CHC1 /CH OH = 90/10, R. = 0.64 N.M.R. (DMSO-d,) 6 p.p.m. : 6 1.10 (3H,t.CH CH ) 2.28 (6H,s,=C-CH ) 3.57 (3H.S.C00CH ) 4.01 (2H,q,CH 2 CH 3 ) 4.93 (lH.s.CH at position of dihydropyridine) 7.05-7.6 (6H,m,phenylic + CH * CH imidazolic protons) 8.09 (lH,dd,N-C -N) 8.88 (lH.s.NH). By proceeding analogously the following compounds may be pre¬ pared: 1,4-dihydro-2,6-dimethyl-4-[3-lH-imidazol-l-yl)phenyl]- -3,5-pyridinedicarboxylic acid, 2-cyanoethyl ethyl ester. Elemental analysis: Found: C 65.38; H 5.73; N 13.15 Calculated for C 23 H 24 N 4 0 4 : C 65.70; H 5.75; N 13.32 N.M.R. (DMSO-dg)δ p.p.m.: 1.10 (3H,t,CH 2 CH 3 ) 2.28 (6H,S,=C-CH 3 ) 2.58 (2H,t,COOCH 2 CH 2 CN) 4.01 (2H,q,CH 2 CH 3 ) 4.05 (2H,t,COOCH 2 CH 2 CN) 4.93 (lH,s,CH at 4 position of dihydropyridine) 7.05-7.6 (6H,m,phenylie + CH=CH imidazolic protons) 8.09 (lH,dd,N-CH-N) 8.88 (1H,S,NH); 1,4 dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl 2-[methyl(phenylmethyl) amino]ethyl ester. Elemental analysis: Calculated for : C H 34 N 4 0 4 : C 70.02; H 6.66; N 10.89 Found: C 69.17; H 6.72; N 10.72 T.L.C: eluant CHCI3/CH3OH •= 95/5 , R f =0.34 N.M.R. (CDCI 3 ) δ p.p.m.: 1.22 (3H,t,C0 2 CH 2 CH 3 ) 2.20 (3H,S,N(CH 3 ) (CH 2 Ph)) 2.37 (6H,s,2=C-CH 3 ) 2.69 (2H,t,CH 2 N(CH 3 ) (CH 2 Ph)) 3.50 (2H,s,N(CH 3 ) (CH 2 Ph)) * 4.11 (2H,q,C0 2 CH 2 CH 3 ) 4.21 (2H,t,C0 2 CH 2 CH 2 -) 5.11 (lH,s,CH at 4 position of dihydropyridine) 5.89 (1H,S,NH) 7.10-7.40 (HH,m,CH at 2,4,5,6 positions of phenyl ring, CH at 4,5 positions of imidazole and phenyl hydrogens of ester function) 7.78 (lH,dd,CH at 2 position of imidazole) MS : m/z 514 M+; 1,4-dihydro-2,6-dimethyl-4-[2-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl methyl ester; 1, -dihydro-2,6-dimethyl-4-[2-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, methyl 2-[methyl(phenylmethyl) amino]ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, isopropyl methyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl isopropyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, methyl 2-[methyl(phenylmethyl) amino]ethyl ester; 1, -dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, isopropyl methyl ester; 1,4-dihydro-2,6-dimethy1-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, methyl 2-[methyl(phenylmethyl) amino]ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl 2-[methyl(phenylmethyl) amino]ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(2-(lH-imidazol-l-yl)phenyl] -3,-5-pyridinedicarboxylic acid, ethyl methyl ester; 1,4-dihydro-2,6-dimethy1-4-[3-(2-(lH-imidazol-l-yl)phenyl] -3,-5-pyridinedicarboxylic acid, methyl 2-[methyl (phenylmethyl)amino]ethyl ester; and 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, 5-amide 3-ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, methyl 2-[methyl(phenylmethyl) amino]ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl 2-[methyl(phenylmethyl) amino]ethyl ester. Example 3 A mixture of 2 g (4.76 mmol) of l,4-dihydro-2,6- dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, 2-cyanoethyl ethyl ester, 3 ml of 2N NaOH and 30 ml of ethanol was stirred for 12 hours at room temperature. The mixture was diluted with water (40 ml) and extracted with ethyl acetate. The aqueous phase was acidified to pH=6 with IN HCl. The precipitate was collected, washed with water and dried under vacuum, giving 0.87 g (50%) of 1,4-dihydro- 2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl ester (monohydrate) , m.p. 117-121"C dec. Elemental analysis: Calculated for C 20 H 23 N 3 O 5 : C 62.32; H 6.01; N 10.90 Found: C 62.12; H 6.07; N 10.85 T.L.C: eluant CHC1 3 /CH 3 0H=9/1, R f =0.31 N.M.R. (DMSO) δ p.p.m.: 1.10 (3H,t,CH 2 CH 3 ) 2.22 (6H,s,2=C-CH 3 ) 4.02 (2H,q,C0 2 CH 2 CH 2 CH 3 ) 4.92 (lH,s,CH at 4 position of dihydropyridine) 7.0-7.60 (6H,m,CH at 2,4,5,6 positions of phenyl ring and CH at 4,5 positions of imidazole) 8.05 (lH,dd,CH at 2 position of imidazole) 8.75 (1H,S,NH); By proceeding analogously the following compounds may be prepared: 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl ester; and 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)ethenyl) phenyl]-3,5-pyridinedicarboxylic acid, ethyl ester. Example 4 A mixture of 1.2 g (0.0065 mol) of 3-(3-pyridyl)benzaldehyde, 1.7 g (0.0131 mol) of ethyl acetoacetate and 1.52 ml of 30% ammonium hydroxide in 10 ml of absolute ethanol was stirred under reflux for 4 hours and at room temperature for two days. The mixture was poured into ice-water and the aqueous solution was extracted with methylene chloride; the organic layers were put together, washed with water, dried over CaCl and evaporated to dryness under vacuum. The residue was purified over flash silica-gel column n-hexane :ethyl acetate = 1:1), giving a solid, which was crystallized from ethyl acetate. The precipitate was filtered off, affording 1.5 g (57%) of l,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl)pheny_T|-3,5- pyridinedicarboxylic acid, diethyl ester, m.p. 183-6°*. Elemental analysis: Found: C 70.99; H 6.46; N 6.84 Calculated for C„_H Λ ,.N„0 • . C 70.92; H 6.45; N 6.89 24 26 2 4 TLC: eluant CHC1 /CH o 0H = 190/10 Rf=0.48 1.21 (6H, t, CH CH ) 2.35 (6H, s, =C-CH ) 4.10 (4H, q, C00CH CH ) 5.09 (1H, ε, CH at 4 position of dihydropyridine) 5.81 (1H, s, NH) 7.20-7.45 (4H, m, CH at 4, 5, 6 positions of phenyl ring and CH at 5 position of pyridine) 7.51 (1H, dd, CH at 2 position of phenyl ring) 7.83 . (1H, ddd, CH at 4 position of pyridine) 8.65 (1H, dd, CH at 6 position of pyridine) 8.80 (1H, d, CH at 2 position of pyridine). By proceeding analogously the following compounds may be prepared: 1 , 4-dihydro-2 , 6-dirne thyl-4- [J3- ( 3-ρyridyl ) phenylj -3 , 5- -pyridinedicarboxylic acid, diisobutyl ester, m.p. 97-8°C, Elemental analysis: Found: C 72.51; H 7.60; N 5.81 Calculated for C__H N O ; C 72.70; H 7.41; N 6.05 28 34 2 TLC: eluant CH CO Et/h-hexane = l/i Rf = 0.2 NMR (CDC1 3 ) S p.p.m : 0.86 and 0.90 (each 6H, 2 d, CH(CH ) ) 1.90 (2H, m, CH -CH(CH ) ) 2.35 (6H, s, =C-CH ) 3.85 (4H, d, C00CH 2 -) 5.15 (1H, s, CH at 4 position of dihydropyridine) 5.70 (1H, s, NH) 7.20 - 7.45 (4H, , CH at 4,5,6 positions of phenyl ring and CH at 5 position of pyridine) 7.52 (1H, bs, CH at 2 position of phenyl ring) 7.81 (1H, ddd, CH at 4 position of pyridine) 8.56 (1H, dd, CH at 6 position of pyridine) 8.80 (1H, d, CH at 2 position of pyridine) ϊ 1,4-dihydro-2,6-diethyl-4-[3-(3-pyridyl)phenyl]-3,5-pyridine¬ dicarboxylic acid, diethyl ester; 1,4-dihydro-2,6-dimethyl-4-[2-fluoro-3(3-pyridyl)pheny \Q- -3,5-pyridinedicarboxylic acid, diethyl ester; 1 , 4-dihydro-2 , 6-dime thyl-4- [3- ( 3-pyridyl ) phenylj -3,5- p yridinedicarboxylic acid, isobutyl methyl ester; 1 , 4 -dihydro-2 , 6-dime hyl-4- _- ( 3-pyridyl )phenylj -3 , 5- pyridinedicarboxylic acid, ethyl ester; 1 , 4-dihydro-2 , 6-dime thyl-4- (j3- ( 3-pyridyl ) phenylj -3 , 5- pyridinedicarboxylic acid, 5-amide-3-ethyl ester; 1 , 4-dihydro-2 , 6-dimethyl-4- [ - ( 3-pyridyl ) phenylj -3 , 5- pyridinedicarboxylic acid, ethyl ester; 1 , 4-dihydro-2 , 6-dimethyl-4- jj3-( 3-pyridyl-methyl )phenyfj -3 , 5- pyridinedicarboxylic acid, diethyl ester; 1 ,4-dihydro-2, 6-dime thyl-4- [3- ( 3-pyridyl-methyl ) phenylj - 3 , 5-pyridinedicarboxylic acid, ethyl ester. Example 5 A mixture of 0.55 g (0.003 mol) of 3-(3-pyridyl)benzaldehyde, 0.75 g (0.003 mol) of 2-[methyl(phenylmethyl)amino]ethyl acetoacetate and 0.38 g (0.003 mol) of ethyl-3-aminocroto- nate in 10 ml of absolute ethanol was stirred under reflux for 30 hours. After cooling, the mixture was poured into ice-water, and the aqueous solution was extracted three times with ethyl acetate. The organic layers were put together, dried over Na_S0 and evaporated under vacuum. The crude product was purified twice over flash silica-gel column n-hexane :ethyl acetate = 1:9; chloroform: methanol = 97:3). The appropriate fractions were put together, evaporated to dryness, affording 0.16 g (10 %) of 1,4-dihydro-2,6-dimethyl- 4-|_3-(3-pyridyl)phenyl]-3,5-pyridinedicarboxylic acid, ethyl 2-[methyl(phenylmethyl )aπ.inq ethyl ester, as an oil. Elemental analysis: Found: C 71.90; H 6.85; N 7.75 Calculated for C H N 0 : C 73.12; H 6.71; N 7.99 TLC: eluant CHC1 /CH OH = 95/5 Rf = 0.5 NMR (CDC1 ) p.p m 1-21 (3 H, t, CH 2 CH 3 ) 2.16 (3 H, s, N(CH 3 )(CH 2 Ph)) 2.35 (6 H, s, =C-CH ) 2.64 (2 H, t, CH N(CH 3 )(CH 2 Ph)) 3.45 (2 H, s, N(CH )(CH_ 2 Ph) ) 4.12 (2 H, q, C00CH 2 CH 3 ) 4. 20 ( 2H , t , C00CH CH - ) 5.11 (1H, s, CH at 4 position of dihydropyridine) 5.98 (iH, s, NH) 7.2C - 7.45 (9H, m, CH at 4,5,6 positions of phenyl ring, CH at 5 position of pyridine and phe¬ nyl hydrogens of ester function) 7.51 (IH, bs, CH at 2 position of phenyl ring) 7.SO (IH, ddd, CH at 4 position of pyridine) 8.54 (iH, dd, CH at 6 position of pyridine) 8.SO (iH, d, CH at 2 position of pyridine). By procee d ing analogously τhe following compoundsmay be prepared: 1,4-dihydro-2,6-diethyl-4-[3-(3-pyridyl)phenyl]-3,5-pyridine¬ dicarboxylic acid, ethyl 2-[methyl(phenylmethyl)amino]ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl)phenylj-3,5-pyri¬ dinedicarboxylic acid, isobutyl 2-jjnethyl(phenylmethyl)amino] ethyl ester. Example 6 The compound l,4-dihydro-2,6-dimethγl-4-[3-(lH-imidazol-1- yl)phenyl]-3,5-pyridinedicarboxylic acid, diethyl ester (0.1 g) was dissolved in isopropyl alcohol (2 ml) and treated with isopropanolic HCl. The solution was evaporated to dryness and the residue crystallized from ethylacetatc/ ethanol (3:1) mixture. The salt l,4-dihydro-2,6-dimethyl-4- -[3-(lH-imidazol-1-y1) henyl]-3,5-pyridinedicarboxylie acid, diethyl ester hydrochloride was obtained in quantitative yield, m.p. 235-240°C (dec). Elemental analysis: Found : C 61. 12 ; H 6 . 16 ; N 9 . 56 Calculated for C 22 H 26 N 3 0 4 C1 : C 61.18; H 6.07; N 9.73. . For the chloride ion: Found : Cl " 8.21% Calculated for C 22 H 2e N 3 0 4 Cl : Cl " 8.23%. Example 7 Tablets, each weighing 150 mg and containing 50 mg of the active substance were manufactured as follows: Composition (for 10,000 tablets) 1,4-dihydro-2,6-dimethyl-4- [3-(lH-imidazol-l-yl)phenyl]- -3,5-pyridinedicarboxylic acid,diethyl ester 500 g Lactose 710 g Corn starch 237.5 g Talc powder 37.5 g Magnesium stearate 15 g 1 , -dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3,5- -pyridinedicarboxylic acid, diethyl ester, lactose and a half of the corn starch were mixed; the mixture was then forced through a sieve of 0.5 mm openings. Corn starch (18 g) was suspended in warm water (180 ml). The resulting paste was used to granulate the powder. The gra les were dried, comminuted on a sieve of sieve size 1.4 mm, t the regaining quantity of starch, talc and magnesium was adde carefully mixed, and processed into tablets using punches of 8 mm diameter. Example 8 Tablets, each weighing 150 mg and containing 50 mg of the active substance were manufactured as follows: Composition (for 10,000 tablets) 1,4-dihydro-2,6-dimethyl-4-(3(3-pyridyl)phenyl)-3,5-pyrid¬ ine dicarboxylic acid,diethyl ester 500 g Lactose 710 g Corn starch 237.5g Talc powder 37.5g Magnesium stearate 15 g 1,4-dihydro-2,6-dimethyl-4-(3(3-pyridyl)phenyl)-3,δpyridi- ne dicarboxylic acid, diethyl ester, lactose and a half of the corn starch were mixed; the mixture was then forced through a sieve of 0.5 mm openings. Corn starch (18g) was suspendend in warm water (180 ml). The resulting paste was used to granulate the powder. The granules were dried, comminuted on a sieve of sieve size 1.4mm, then the remaining quantity of starch, talc and magnesium was added, carefully mixed, and processed into tablets using punches of 8 mm diameter.

Claims: CIAIMS 1. A compound having the following formula (I) wherein A represents a d rect linkage, -CH 2 -, -CH -CH 2 - or, when Het is , A may also represent -CH=CH-; R is hydrogen, halogen, C^ -C 3 alkyl or C 2 -C 3 alkoxy; each of R 3 and 4, which may be the same or different, is a C^ -C 3 alkyl group; one of R*L and R 2 is a group -OR' wherein R' is C* * L-C 6 alkyl either unsubstituted or omega substituted by C-^-C- 3 alkoxy or cyano, and the other is, independently, (a) a group -OR' as defined hereabove; or (b) a group wherein each of R" and R"* , which may be the same or different, is hydrogen or C*χ-C 3 alkyl; or (c) a group -OR wherein R is hydrogen or a substituent selected from the group consisting of (i) ~(CH 2 ) m -CH=CH-Ph, wherein m is an integer of 1 to 3 and Ph is a phenyl group either unsubstituted or substituted by one to three substituents chose among Cι~C alkyl, C^-c alkoxy and halogen; ( Ph is as defined above; Q is a C 2 -C 5 alkylene radical; n is zero, 1 or 2; and each R v is, independently, hydrogen, C ! -C 3 alkyl or Ph, wherein Ph is as defined above; R (iii) -(CH 2 ) m -N N-(CH) n -Ph wherein m, n, R v and Ph are as defined above; and /— P«hι (iv) -(CH ) D -N X wherein p is 2 or 3 and Ph is \ Ph as defined above, and the pharmaceutically acceptable salts thereof. 2. A compound of formula (I), according to claim 1, wherein R is hydrogen, R 3 and R4 are both methyl groups or both ethyl groups, and each of R-^ and R 2 , which may be the same or different, is a group -OR' wherein R 1 is unsubstituted C^-Cg alkyl, and their pharmaceutically acceptable salts. 3. A compound of formula (I), according to claim 1, wherein: R is hydrogen; R and R 4 are both methyl groups or both ethyl groups; one of R-χ and R 2 is a group -OR' wherein R' is unsubstituted C-^-Cg alkyl and the other is, independently, a group wherein R" and R" ■ are both hydrogen; or a group -OR IV wherei.n RIV i.s hydrogen or one of the groups (i) and (ii) defined in claim 1, and their pharmaceutically acceptable salts. 4. A compound of formula (I), according to claim 1, selected from the group consisting of: 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, dimethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl methyl ester; 1,4-dihydro-2,6-dimethyl-4- 3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid diethyl ester; 1,4-dihydro-2,6-dimethyl-4- 3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid isopropyl methyl ester; l,4-dihydro-2,6-dimethyl-4- 3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid ethyl isopropyl ester; 1, -dihydro-2,6-dimethyl-4- 3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid methyl 2-[methyl(phenylmethyl) amino]ethyl ester; l,4-dihydro-2,6-dimethyl-4- 3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid ethyl 2-[methyl(phenylmethyl) amino]ethyl ester; 1,4-dihydro-2,6-dimethyl-4- 2-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid dimethyl ester; 1,4-dihydro-2,6-dimethyl-4- 2-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid diethyl ester; 1,4-dihydro-2,6-dimethy1-4- 2-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid ethyl methyl ester; 1,4-dihydro-2,6-dimethyl-4- 2-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid methyl 2-[methyl(phenylmethyl) amino]ethyl ester; 1,4-dihydro-2 ,6-dimethyl-4- 3-(lH-imidazol-l-yl)phenyl]-3. 5-pyridinedicarboxylic acid dimethyl ester; 1,4-dihydro-2,6-dimethyl-4- 3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid diethyl ester; 1,4-dihydro-2,6-dimethyl-4- 3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid isopropyl methyl ester; 1,4-dihydro-2,6-dimethyl-4- 3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid methyl 2-[methyl(phenylmethyl) amino]ethyl ester; 1,4-dihydro-2,6-dimethy1-4- 3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid ethyl 2-[methyl(phenylmethyl) amino]ethyl ester; 1,4-dihydro-2,6-dimethyl-4- 2-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid dimethyl ester; SUBSTITUTESHEET 1,4-dihydro-2,6-dimethyl-4-[3-(2-(lH-imidazol-l-yl) ethenyl)phenyl] -3,5-pyridinedicarboxylic acid, ethyl methyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(2-(lH-imidazol-l-yl) ethenyl)phenyl]-3,5-pyridinedicarboxylic acid, diethyl ester; l,4-dihydro-2,6-dimethyl-4-[3-(2-(lH-imidazol-l-yl) ethenyl)phenyl]-3,5-pyridinedicarboxylic acid, dimethyl 2-[methyl(phenylmethyl)amino]ethyl ester. 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl)phenyl]-3, 5-pyridinedicarboxylic acid, 5-amide 3-ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-1-yl-methyl) phenyl]-3,5-pyridinedicarboxylic acid, ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(2-(lH-imidazol-l-yl) ethenyl)phenyl]-3,5-pyridinedicarboxylic acid, ethyl ester; 1,4-dihydro-2,6-dimethy1-4-[3-(3-pyridyl)phenyl]-3, 5-pyridinedicarboxylic acid, isobutyl methyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl)phenyl]-3, 5-pyridinedicarboxylic acid, diethyl ester; 1,4-dihydro-2,6-dimethy1-4-[3-(3-pyridyl)phenyl]-3, 5-pyridinedicarboxylic acid, diisobutyl ester; 1,4-dihydro-2,6-dimethy1-4-[3-(3-pyridyl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl)phenyl]-3, 5-pyridinedicarboxylic acid, 5-amide-3-ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl 2-[methyl(phenylmethyl) amino] ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl)phenyl]-3, 5-pyridinedicarboxylic acid, isobutyl 2-[methyl(phenyl¬ methyl)amino] ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[4-(3-pyridyl)phenyl]-3, 5-pyridinedicarboxylic acid, diethyl ester; 1, -dihydro-2,6-dimethyl-4-[4-(3-pyridyl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl-methyl)phenyl]-3, 5-pyridinedicarboxylic acid, diethyl ester; 1,4-dihydro-2,6-dimethyl-4-[3-(3-pyridyl-methyl)phenyl]-3, 5-pyridinedicarboxylic acid, ethyl ester; and the pharmaceutically acceptable salts thereof. 5. A compound of formula (I) , according to claim 1, which is l,4-dihydro-2,6-dimethyl-4-[3-(lH-imidazol-l-yl) phenyl]-3,5-pyridinedicarboxylic acid diethyl ester, and the pharmaceutically acceptable salts thereof. 6. A process for the preparation of a compound of formula (1) as defined in claim 1 or a pharmaceutically acceptable salt thereof, the process comprising: (a) reacting a compound of formula (II) wherein R, A, Het, R 2 and R 3 are as defined in claim 1, but R is different from -OH, with a compound of formula (III) (III) wherein R-L and R4 are as defined in claim 1, but R-^ is different from -OH, thus obtaining a compound of formula (I) wherein R, A, Het, R-L, R 2 , R 3 and R are as defined in claim 1 with the exception of a compound of formula (I) wherein one of R-*L and R is -OH; or (b) reacting a compound of formula (II) with a compound of formula (IV) CH -COR / 2 l (IV) 0=C ' \ wherein R- j _ and R 4 are as defined in claim 1, but R--_ is different from -OH, in the presence of an ammonium salt or hydroxide, thus obtaining a compound of formula (I) wherein R, A, Het, R lf R 2 , R 3 and R 4 are as defined in claim 1, with the exception of a compound of formula (I) wherein one of R^ and R 2 is -OH; or (c) reacting a compound of formula (V) wherein R, A and Het are as defined in claim 1, with a compound of formula (III) and a compound of formula (IV) together, thus obtaining a compound of formula (I) wherein R, A, Het, lf R 2 , R 3 and R 4 are as defined in claim 1, with the exception of a compound of formula (I) wherein one of R-^ anα ^ R 2 •* LS ~" 0H ' or (d) reacting a compound of formula (V) with a compound of formula (IV) wherein R*^ is a group -OR 1 as defined in claim 1, in the presence of an ammonium salt or hydroxide, thus obtaining a compound of formula (I) wherein R, A, Het, R 3 and R4 are as defined in claim 1, and each of R*** ^ and R 2 is a group -OR 1 wherein R 1 is as defined in claim 1 and wherein -^ is equal to R 2 , and R 3 is equal to R 4 ; or (e) transforming a compound of formula (I) wherein one of R-L and R 2 is different from -OH into a corresponding compound of formula (I) wherein one of R*** ^ and R 2 is -OH; and, if desired, converting a compound of formula (I) into another compound of formula (I) , and/or, if desired, converting a compound of formula (I) into a pharmaceutically acceptable salt thereof, and/or, if desired, converting a salt into a free compound, and/or, if desired, separating a mixture of isomers of formula (I) into the single isomers. 7. A pharmaceutical composition comprising a suitable carrier and/or diluent and, as an active principle, a compound of formula (I) as defined in claim 1 or a pharmaceutically acceptable salt thereof. 8. A compound of formula (I) or a salt thereof, according to claim 1, for use in inhibiting Thromboxane A 2 Synthase activity and/or as a calcium antagonist.

Inventors: CARGANICO GERMANO, COZZI PAOLO, MENICHINCHERI MARIA, SALVATI PATRICIA, CARGANICO, GERMANO, COZZI, PAOLO, MENICHINCHERI, MARIA, SALVATI, PATRICIA
Applicants: ERBA CARLO SPA, FARMITALIA CARLO ERBA S.R.L.
Application year: 1989
Main classification: C07D401
IPC codes: A61K31, A61P7, C07D213, C07D401, C07D521