Certain 1,4-dihydro-2,6-dilower-alkyl-4-(mono-substituted pyridyl) useful for treating coronary artery or cerebral artery disease

Abstract

There is provided a dihydropyridine derivative having the formula ##STR1## wherein R'.sub.1 denotes methyl, chlorine, bromine, fluorine, trifluoromethyl, nitro, cyano or methoxy, R.sub.7 denotes benzyl; and the dihydropyridine links to the 2-, 3-, or 4-position of the pyridine.The compound has an activity as a Ca-antagonist, and is useful for treating vascular disorders such as coronary artery disease, celebral artery disease, hypertension and the like.

Description

This invention relates to a novel 4-pyridyldihydropyridine derivative. More particularly, it is concerned with a 4-pyridyl-dihydropyridine derivative having an activity such as calcium-antagonism, blood pressure lowering and phosphodiesterase inhibition.

Hitherto, a 4-phenyl-dihydropyridine-3,5-dicarboxylic acid ester has been known as having such activity (U.S. Pat. No. 3,644,627). For Example, 2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid dimethyl ester has been on market as being called Nifedipine (The Merck Index, 10th Edition). In view of improving water solubility of the dimethyl ester compound, an improvement was made by changing at least one of the ester moieties to an N-substituted aminoalkyl ester (U.S. Pat. No. 3,985,758), among which 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester is described as being called Nicardipine in the Merck Index.

Although it is already known that these compounds are useful as an antihypertensive agent, vasodilator for peripheral and celebral blood vessels, and curative for coronary artery disorders (angina pectoris) relying on the above-mentioned activity, emergence of a dihydropyridine derivative having a more excellent effect is eagerly awaited.

An object of this invention is to provide a dihydropyridine derivative and the innoxious salt thereof, which have a more excellent pharmacological activity.

Another object of this invention is to provide a pharmaceutical composition comprising a dihydropyridine derivative having an excellent pharmacological activity.

This invention provides a novel dihydropyridine derivative (I) represented by the general formula ##STR2## wherein R.sub.1 and R.sub.2 are the same as or different from each other and denote each hydrogen, provided that they cannot be hydrogen at the same time, or a nitro, cyano, halogen, alkyl, halogenated alkyl, alkoxy, halogenated alkoxy, alkylmercapto, alkylsulfinyl or alkylsulfonyl; R.sub.3, R.sub.4 and R.sub.5 denote independently an alkyl; R.sub.6 and R.sub.7 independently denote hydrogen or alkyl or aralkyl which may be optionally substituted with halogen, or form a heterocyclic ring jointly with the adjacent nitrogen atom; X denotes a group --COO--; and A denotes an alkylene group; and an innoxious salt thereof. The present compounds have such an excellent Ca-antagonistic activity, antihypertensive effect, thrombocyte agglutination inhibition effect and phosphodiesterase inhibition effect and are useful as a medicine, for example as a coronary vessel vasodilator, celebral blood flow increasing agent, antihypertensive agent, preventive or curative agent for thrombosis, and phosphodiesterase inhibitor. Also, this invention provides a pharmaceutical composition comprising at least one member selected from the group consisting of the said dihydropyridine derivatives (I) and the innoxious salts thereof.

The dihydropyridine derivative (I) of this invention has a unique structure as compared with the prior dihydropyridine compounds known in the art and hence has a unique activity originating from the structure. Thus, it is expected that the dihydropyridine derivative (I) of this invention has a high organ and tissue selectivity, particularly in vasodilating action, and hence can attain an excellent pharmacological effect at a relatively small dose. As a result, it is characterized by its reduced systemic side effects.

In the present specification, halogen or halogenated means fluorine, chlorine, bromine and iodine, or their substituent. Preferably, it is fluorine, chlorine, and bromine, and preferably fluorine and bromine for R.sub.1 and R.sub.2. Alkyl may be either of straight chain or branched chain and includes, for example, alkyls of 1 to 6 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl and hexyl and preferably methyl for R.sub.3, R.sub.4, and R.sub.5. Aralkyl groups include phenyl C.sub.1 -C.sub.3 alkyl group, for example, benzyl, phenethyl, 1-phenylethyl, 3-phenylpropyl, 2-phenylpropyl and 1-phenylpropyl, the said phenyl groups being optionally substituted with substituents such as an alkyl and halogen, among which benzyl is preferred for R.sub.6 or R.sub.7. Alkylene groups have preferably 2 to 4 carbon atoms, may be either of straight chain or branched chain and include, for example, ethylene, trimethylene, propylene, tetramethylene, and 1,2-dimethylethylene group, and preferably ethylene group.

In the present specification, the alkyl moiety and halogen in the alkoxy, halogenated alkyl, alkylmercapto, alkylsulfinyl, and alkylsulfonyl group for R.sub.1 or R.sub.2 are the same as the above-defined alkyl and halogen. The halogenated alkyl may be those in which a part of their hydrogen atoms have been halogenated [(CF.sub.3).sub.2 CHCH.sub.2 --, CF.sub.3 CH.sub.2 -- etc.] or those in which all of the hydrogen atoms have been halogenated (trifluoromethyl etc.), and trifluoromethyl is preferable for R.sub.1 and R.sub.2. Also, the halogenated alkoxy may be either those in which a part of their hydrogen atoms have been halogenated or those in which all of the hydrogen atoms have been halogenated.

In the general formula (I), the heterocyclic ring formed by R.sub.6 and R.sub.7 together with adjacent nitrogen atom may contain an additional hetero atom. Examples of such hetero atoms include an oxygen, a nitrogen and a sulfur atom. Examples of the heterocyclic ring include pyrrolidine, piperidine, morpholine, piperazine, 1,2,3,4-tetrahydroquinoline, 1,2,3,4-tetrahydroisoquinoline, imidazole, indole, isoindole, and benzimidazole. The heterocyclic ring may be optionally substituted by alkyl, aralkyl, halogen etc., which are the same as the above.

In the general formula (I), the position of pyridyl group to be connected at the 4-position of dihydropyridine is preferably the 2-, 3-, or 4-position thereof; and the position of the substituent R.sub.1 or R.sub.2, which are not hydrogen, may preferably be at a position next or next to one to the bond site of the pyridyl group with the dihydropyridyl group. Further, the relative position of the R.sub.1 and the R.sub.2 when the both present, is next, next to one or every third to each other.

The dihydropyridine derivative (I) can be piepared by reacting an optional part constituting the dihydropyridine derivative (I) with the remaining part of the derivative by a method known per se, particularly by subjecting them to dehydrating cyclization. For example, it can be prepared as follows. ##STR3##

In the above formulas R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, X and A are as defined above. ##STR4## In the above formulas R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, X and A are as defined above.

Each of the above-mentioned methods of preparation will be described in detail below.

Method of preparation (A)

In this method, the compounds (II), (III) and (IV) are first reacted in an appropriate solvent to prepare the compound (V). This reaction is carried out usually at about 30.degree. C. to 150.degree. C., preferably about 50.degree. C. to 120.degree. C., and particularly when the solvent used boils in the above-mentioned temperature range, at the boiling point. The solvent to be used is not particularly limited so long as it is inert to the reaction and includes, for example, alcohols such as methanol, ethanol, propanol, and isopropanol; ethers such as tetrahydrofuran, dioxane, and dimethoxyethane; N,N-dimethylformamide, dimethylsulfoxide, and acetonitrile. The reaction usually requires 1 to 20 hours for completion. As to the amount of the compounds (II), (III) and (IV) to be used, for 1 mole of any one of the three compounds 1 to 1.5 moles of each of the other two compounds is used. The starting compound (II) is already known or can be prepared by a known method [cf., for example,. J, Am. Chem. Soc., 67, 1017 (1945)]. The compound (IV) is already known or can be prepared by a known method [cf., for example, Chem. Pharm. Bull., 27 (6), 1426 (1979)]. The various substituted pyridine aldehyde (III) can be obtained by preparing the pyridine alcohol shown below by a known method and then oxidizing it with, for example, dimethylsulfoxide (DMSO)-dicyclohexylcarbodiimide (DCC)-phosphoric acid. ##STR5##

The compound (V) thus obtained is then treated with a secondary amine of the formula HN (R.sub.6) (R.sub.7) (R.sub.6 and R.sub.7 are the same as above) to give the dihydropyridine derivative (I). This reaction is carried out usually at about 50.degree. C. to 130.degree. C., preferably at about 70.degree. C. to 110.degree. C. Examples of preferred solvents to be used include toluene and N,N-dimethylformamide. The reaction is usually carried out by using 2 to 2.5 moles of the secondary amine relative to 1 mole of the compound (V). The reaction usually requires 1 to 20 hours for completion.

Method of preparation B

This method can be effected under substantially the same conditions as in the method A. The starting compound (VI) to be used in this method can be prepared by treating the starting compound (IV) used in the method A with the said secondary amine. Thus, it is easily prepared by dissolving the compound (IV) in a suitable solvent (for example, ethanol, dioxane, tetrahydrofuran, N,N-dimethylformamide), then adding to the solution the solution of about 2.5 equivalents of the secondary amine of the formula ##STR6## and allowing the mixture to react at about 30.degree. C. to 110.degree. C. for 1 to 18 hours.

The novel dihydropyridine derivative (I) thus prepared can be recovered by optional means of separation and purification, for example, concentration, extraction, chromatography, reprecipitation and recrystallization, to collect a product in desired purity. Further, since the dihydropyridine derivative (I) has a basic group, it can also be converted to an acid addition salt by a conventional method. Such acid addition salts are not particularly limited so long as they are pharmaceutically acceptable and innoxious, and include, for example, inorganic acid salts (such as hydrochloride, hydrobromide, phosphate and sulfate) and organic acid salts (such as acetate, succinate, maleate, fumarate, malonate and tartrate).

The compounds having simultaneously a hydrogen atom for R.sub.1 and R.sub.2 are not sufficient in their activity, and the preferable compounds of the invention are exemplified as follows:

(1) 2,6-Dimethyl-4-(3-nitro-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (2) 2,6-Dimethyl-4-(4-bromo-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (3) 2,6-Dimethyl-4-(4-cyano-2-pyridyl)-1,4-dihydropyridyne-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (4) 2,6-Dimethyl-4-(4-trifluoromethyl-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (5) 2,6-Dimethyl-4-(4-nitro-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (6) 2,6-Dimethyl-4-(6-bromo-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (7) 2,6-Dimethyl-4-(6-chloro-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (8) 2,6-Dimethyl-4-(6-cyano-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (9) 2,6-Dimethyl-4-(6-trifluoromethyl-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (10) 2,6-Dimethyl-4-(6-nitro-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (11) 2,6-Dimethyl-4-(2-bromo-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester. (12) 2,6-Dimethyl-4-(2-cyano-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (13) 2,6-Dimethyl-4-(2-trifluoromethyl-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(benzyl-N-methylamino)ethyl ester 5-methyl ester. (14) 2,6-Dimethyl-4-(5-bromo-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (15) 2,6-Dimethyl-4-(6-cyano-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (16) 2,6-Dimethyl-4-(2-fluoro-4-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (17) 2,6-Dimethyl-4-(5-trifluoromethyl-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (18) 2,6-Dimethyl-4-(5-nitro-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (19) 2,6-Dimethyl-4-(2-cyano-4-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester. (20) 2,6-Dimethyl-4-(3-trifluoromethyl-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

The dihydropyridine derivative (I) and its innoxious salt according to this invention are of low toxicity, exert a strong and long-lasting blood pressure depressing action, peripheral blood vessel vasodilating action, coronary artery vasodilating action and celebral blood vessel vasodilating action on mammals such as mice, rats, rabbits, dogs, cats, and humans, and are useful as, for example, a preventive or curative agent for diseases of circulatory systems in humans, for example, hypertension, ischemic cardiac diseases (e.g. angina pectoris and myocardial infarction), and celebral and peripheral circulatory disorders (e.g. celebral infarction and transient celebral ischemic attack).

Particularly, they are excellent in both the intensity and/or the duration of their pharmacological effect as compared with dihydropyridine derivatives of prior art (for example Nifedipine and Nicardipine) and hence, when used as a preventive or curative agent for hypertension for example, can give a stable depression effect at a less number of times of administration (1 to 2 times per day).

When the dihydropyridine derivative (I) or its innoxious salt are used as the above-mentioned medicaments, they can be mixed with such pharmaceutically necessary ingredients as appropriate, pharmaceutically compatible carriers, additives, and diluents and made up into pharmaceutical compositions in the form of powders, granules, tablets, capsules, and injections, to be administered orally or parenterally.

The above-mentioned pharmaceutical preparations contain an effective amount of the dihydropyridine derivative (I) incorporated therein. The dosage varies depending upon the route of administration, the conditions, weight or age of patients, and other factors. In oral administration to adult hypertension patients for example, it is preferably administered at a dose of 0.05 to 20 mg/kg body weight/day, more preferably 0.1 to 4 mg/kg body weight/day, divided in 1 to several times per day.

The results of pharmacological tests conducted to show the effectiveness of the dihydropyridine derivative (I) and its innoxious salt of this invention are described below.

The results (LD.sub.50) of acute toxicity test of the present Ca-antagonist (P.O.) in mice are 650.degree.-950 mg/kg.

Blood pressure depression effect

Test 1

Male, spontaneously hypertension-developing rats of ages of 10 to 11 weeks (in groups of 3 to 5 animals) were used in the test. For blood pressure determination, systolic pressure was measured without anesthesia by an indirect tail-cuff method using a sphygmomanometer (PE-300, Narco Bio-System).

The compound to be tested was orally administered (at a dose of 25 mg/kg in terms of the active compound) as a 10% HCO-60 (polyoxyethylene hardened castor oil) suspension. Blood pressure was determined 1, 4 and 7 hours after the administration. Table 1 shows the respective average value of the blood pressure (in mmHg).

TABLE 1______________________________________ Systolic blood pressure (mmHg) BeforeCompound admini- After After AfterExample stration 1 hr 4 hrs 7 hrs______________________________________1 193 115 137 1483 198 126 143 1615 195 156 135 1406 190 139 145 145______________________________________

Further, the blood pressure depression effect of the fumarate of the compound obtained in Example 28 described later was examined in the same manner as described above. The result obtained showed that the maximum depression value (%) of blood pressure from the value (100%) before administration was 67%, and the time required for 50% recovery from maximum depression value (%) of blood pressure was 16.2 hours.

Test 2

The above Test 1 was repeated with respect to a various compounds of the invention as well as Nicardipine and Nifedipine, including the compounds in Table 1, provided that the time after the administration was prolonged till 24 hours, and the blood pressure lowering maximum and the duration until the pressure recovered to 50% from the maximum depression value (%) of blood pressure were measured.

The results are shown as in Table 2, the changes of blood pressure being expressed as percent based on that before administration.

TABLE 2______________________________________ Duration Before Depression value (%) 50%Compound admini- of blood pressure recoveryNo. stration 1h 2h 4h 7h 24h Max (h)______________________________________Nic 100 62 68 76 81 96 62 7.0Nif 100 72 73 77 70 90 70 19.4(1) 100 65 68 76 81 96 65 8.7(2) 100 70 76 75 92 102 70 5.8(3) 100 61 66 74 82 95 61 7.0(5) 100 67 82 93 90 104 67 2.3(6) 100 63 72 86 83 99 63 3.5(7) 100 83 84 87 93 101 83 6.0(8) 100 69 74 84 88 98 69 4.4(9) 100 85 92 91 104 119 85 4.6(10) 100 99 95 107 110 120 95 2.4(11) 100 83 82 87 91 97 82 6.7(12) 100 66 71 76 88 98 66 5.6(13) 100 73 67 67 71 94 67 16.2(14) 100 83 91 90 90 101 83 9.3(15) 100 88 90 83 89 95 83 15.1(16) 100 92 94 95 98 96 92 5.5(17) 100 91 92 95 98 105 91 4.2(18) 100 90 86 95 96 96 86 3.7(19) 100 75 94 100 98 99 75 1.7______________________________________

This invention will be explained in more detail below with reference to Examples.

EXAMPLE 1

(1) 2,6-Dimethyl-4-(6-cyano-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-chloroethyl ester 5-methyl ester

6-Cyano-2-pyridine aldehyde (1.613 g, 12.2 mmol), chloroethyl acetoacetate (2.009 g, 12.2 mmol) and methyl 3-aminocrotonate (1.364 g, 12.2 mmol) were dissolved in 16 ml of isopropanol, and the solution was stirred at 35.degree. to 40.degree. C. under a nitrogen gas stream for 14 hours. The reaction solvent was distilled off under reduced pressure, and the residue was purified by column chromatography [silica gel; ethyl acetate-n-hexane (5:6)]. The crude product thus obtained was recrystallized from isopropyl ether-methanol to obtain 1.546 g (34% yield) of the above-captioned compound.

IR .nu..sub.max.sup.KBr cm.sup.-1 : 2225(CN), 1695(C=O); 1680(C=O) ##STR7##

(2) 2,6-Dimethyl-4-(6-cyano-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

The chloroethyl ester compound (1.546 g, 4.11 mmol) obtained in (1) and N-methyl-N-benzylamine (1.047 g, 8.64 mmol) were dissolved in 12 ml of N,N-dimethylformamide, and the solution was stirred at 100.degree. to 105.degree. C. under a nitrogen gas stream for 11.5 hours. The reaction solvent was distilled off under reduced pressure. The resulting residue was mixed with water and extracted with diethyl ether. The diethyl ether layer was washed with water, dried, and then the solvent was distilled off under reduced pressure. The residue was purified by column chromatography [silica gel; ethyl acetate-n-hexane (3:1)]. Thus, 449 mg (29% yield) of the starting material was recovered as the first fraction, and then 929 mg of the crude objective compound was obtained as the second fraction. The crude product was further purified by column chromatography [silica gel; chloroform-methanol (96:4)] to obtain 882 mg (47% yield) of the objective compound.

IR .nu..sub.max.sup.CHCl.sbsp.3 cm.sup.-1 : 2225(CN), 1635(C=O.times.2) ##STR8##

EXAMPLE 2

The objective compound obtained in Example 1 (858 mg, 1.86 mmol) and fumaric acid (216 mg, 1.86 mmol) were dissolved in 25 ml of ethanol, and the solution was stirred at room temperature for 70 minutes. The reaction solvent was distilled off under reduced pressure to obtain 1.07 g of the fumaric acid salt of the compound.

IR .nu..sub.max.sup.KBr cm.sup.-1 : 3300(COOH), 2200(CN), 1690(C=0.times.4) ##STR9##

EXAMPLE 3

(1) 2,6-Dimethyl-4-(6-bromo-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-chloroethyl ester 5-methyl ester

A solution of 6-bromo-2-pyridine aldehyde (1.542 g, 8.29 mmol), chloroethyl acetoacetate (1.388 g, 8.43 mmol) and methyl 3-aminocrotonate (948 mg, 8.29 mmol) in 12 ml of isopropanol was stirred under a nitrogen gas stream, at 40.degree. C. for 9 hours and at room temperature for 13 hours. The reaction solvent was distilled off under reduced pressure, and the residue was purified by column chromatography [silica gel; ethyl acetate-n-hexane (2:3)]. The crude product thus obtained was recrystallized from isopropyl ether-methanol to obtain 1.730 g (49% yield) of the above-captioned compound (m.p. 152.degree. to 153.degree.C.).

IR .nu..sub.max.sup.KBr cm.sup.-1 : 1705(C=O), 1680(C=O) ##STR10##

(2) 2,6-Dimethyl-4-(6-bromo-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-methylamino)ethyl ester 5-methyl ester

The chloroethyl ester compound (1.509 g, 3.51 mmol) obtained in (1) and N-methyl-N-benzylamine (894 mg, 7.37 mmol) were dissolved in 11 ml of N,N-dimethylformamide, and the solution was stirred at 100.degree. to 105.degree. C. under a nitrogen gas stream for 15.5 hours. The reaction solvent was distilled off under reduced pressure. The residue was mixed with water and extracted with ethyl acetate. The ethyl acetate layer was washed with water, dried, and then the solvent was distilled off under reduced pressure. The residue was purified by column chromatography [silica gel; ethyl acetate-n-hexane (5:2)]. The crude product thus obtained was recrystallized from isopropyl ether-methanol to obtain 1.141 g (63% yield) of the objective compound. M.p.: 123.5.degree. to 124.5.degree. C.

IR .nu..sub.max.sup.KBr cm.sup.-1 : 1695(C=O.times.2) ##STR11##

EXAMPLE 4

The object compound (1.037 g, 2.02 mmol) obtained in Example 3 and fumaric acid (234 mg, 2.02 mmol) were dissolved in 24 ml of ethanol, and the solution was stirred at room temperature for 4 hours. The reaction solvent was distilled off under reduced pressure to obtain 1.2 g of the fumaric acid salt of the compound.

IR .nu..sub.max.sup.KBr cm.sup.-1 : 3375(COOH), 1695(C=O.times.4) ##STR12##

EXAMPLE 5

2,6-Dimethyl-4-(4-nitro-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester

The same procedures as those in Example 1 were followed by using 4-nitro-2-pyridine aldehyde in place of 6-cyano-2-pyridine aldehyde to obtain the compound in 25% yield (m.p.: 163.degree. C., methanol).

IR .nu..sub.max.sup.KBr cm.sup.-1 : 3070, 2950, 1700, 1670, 1640, 1620, 1580 ##STR13##

EXAMPLE 6

2,6-Dimethyl-4-(2-trifluoromethyl-4-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester

The same procedures were followed as those in Examples 3 by using 2-trifluoromethyl-4-pyridine aldehyde in place of 6-bromo-2-pyridine aldehyde to obtain the above objective compound in the form of oil (55% yield).

IR .nu..sub.max.sup.KBr cm.sup.-1 : 3350, 2950, 2800, 1690(broad), 1460(broad) ##STR14##

EXAMPLES 7 TO 39

The compounds shown in Tables 3 to 6 were obtained in the same manner as in any one of Examples 1 to 6.

TABLE 3__________________________________________________________________________ ##STR15##Example R.sub.1 R.sub.2 R.sub.3 R.sub.4 R.sub.5 ANR.sub.6 R.sub.7 M.p. Property__________________________________________________________________________ 7 Cl H CH.sub.3 CH.sub.3 CH.sub.3 ##STR16## 116-118.degree. C. (Isopropyl Pale yellow powder 8 Br " " " " " 123.5-124.5.degree. C. Pale yellow (Isopropyl ether) powder 9 CN " " " " " -- Pale yellow oil10 " " " " " ##STR17## -- Yellow oil11 H OMe " " " ##STR18## 131-133.degree. C. (Ethyl Slightly yellow crystal12 " NO.sub.2 " " " " 157-159.degree. C. Slightly (Methanol) yellow crystal13 CH.sub.3 H " " " " -- Pale yellow oil14 CF.sub.3 " " " " " -- "15 " " " " " ##STR19## -- "16 H NO.sub.2 " " " ##STR20## -- Pale yellow oil17 CN " " " " ##STR21## 163.degree. C. (Methanol) Pale yellow crystal18 H CF.sub.3 " " " " -- Pale yellow powder18 " " " " " " -- Pale yellowfumarate powder19 NO.sub.2 H " " " " -- Yellow oil19 " " " " " " -- "fumarate20 H Br " " " " -- Pale yellow powder20 " " " " " " -- Pale yellowfumarate powder21 " CN " " " " 176-177.degree. C. Pale yellow (Isopropyl ether- powder methanol)21 " " " " " " -- Pale yellowfumarate powder__________________________________________________________________________ TABLE 4__________________________________________________________________________ ##STR22##Example R.sub.1 R.sub.2 (R'.sub.2) R.sub.3 R.sub.4 R.sub.5 ANR.sub.6 R.sub.7 M.p. Property__________________________________________________________________________22 H Br (R'.sub.2) CH.sub.3 CH.sub.3 CH.sub.3 ##STR23## -- Pale yellow oil23 " CN " " " " -- "24 Br H " " " " 149-151.degree. C. Pale yellow powder (Isopropyl ether)25 CN " " " " " 169-170.5.degree. C. " (Isopropyl ether)26 H NO.sub.2 (R'.sub.2) " " " " 139-141.5.degree. C. Yellow powder (Ethyl acetate)27 F H " " " " 79-82.degree. C. Pale yellow powder (Isopropyl ether)28 CF.sub.3 " " " " " -- "28 " " " " " " -- "fumarate29 CN " " " " ##STR24## -- Pale yellow oil30 CF.sub.3 " " " " ##STR25## -- "31 H CF.sub.3 (R'.sub.2) " " " ##STR26## -- "31 " " " " " " -- Pale yellow powderfumarate__________________________________________________________________________ TABLE 5__________________________________________________________________________ ##STR27##Example R.sub.1 R.sub.2 R.sub.3 R.sub.4 R.sub.5 ANR.sub.6 R.sub.7 M.p. Property__________________________________________________________________________32 Br H CH.sub.3 CH.sub.3 CH.sub.3 ##STR28## Pale yellow oil33 CN " " " " " (IR. 2225 cm.sup.-1) "34 F " " " " " "35 CF.sub.3 " " " " " "36 " " " " " ##STR29## "37 CN CN " " " ##STR30## 132-134.degree. C. (Methanol) Pale yellow powder__________________________________________________________________________ TABLE 6______________________________________ ##STR31##Ex-am-ple R.sub.1 R.sub.2 R.sub.4 R.sub.5 ANR.sub.6 R.sub.7 Property______________________________________38 CF.sub.3 CH.sub.3 CH.sub.3 CH.sub.3 ##STR32## Pale yellow powder38 " " " " " "fu-ma-rate39 NO.sub.2 " " " " Yellow oil39 " " " " " Yellowfu- oilma-rate______________________________________

Some of the compounds obtained in Examples 7 to 39 can be identified by means of nuclear magnetic resonance and others, as shown in Table 7.

TABLE 7__________________________________________________________________________ExampleNo. HNMR .delta. CDCl.sub.3 Other properties__________________________________________________________________________14 ##STR33## .sup.19 FNMR .phi. (CDCl.sub.3): -67.8 ppm14 fumarate ##STR34## .sup.19 FNMR .phi. (DMSO-d.sub.6 ): -65.9 ppm IR .nu..sub.max.sup.KBr cm.sup.-1 : 1700(CO)18 ##STR35## .sup.19 FNMR .phi. (CDCl.sub.3): -64.8 ppm IR .nu..sub.max.sup.KBr cm.sup.-1 : 1700(CO)18 fumarate ##STR36## .sup.19 FNMR .phi. (CDCl.sub.3, MSO-d.sub.6): -63.3 ppm IR .nu..sub.max.sup.KBr cm.sup.-1 : 1710(CO)19 ##STR37## IR .nu..sub.max.sup.CHCl.sbsp.3 cm.sup.-1 : 1690(CO), 1540(NO.su b.2) 1355(NO.sub.2)19 fumarate ##STR38## ##STR39##20 ##STR40## IR .nu..sub.max.sup.KBr cm.sup.-1 : 1700(CO), 1675(CO)20 fumarate ##STR41## ##STR42##21 ##STR43## IR .nu..sub.max.sup.KBr cm.sup.-1 : 2250(CN), 1710(CO), 665(CO)21 fumarate ##STR44## ##STR45##27 ##STR46## .sup.19 FNMR .phi. (DMSO-d.sub.6 , CDCl.sub.3): -72 ppm IR .nu..sub.max.sup.KBr cm.sup.-1 1700(CO)27 fumarate ##STR47## ##STR48##28 ##STR49## .sup.19 FNMR .phi. (CDCl.sub.3): -61 ppm IR .nu..sub.max.sup.KBr cm.sup.-1 : 1700(CO)28 fumarate ##STR50## .sup.19 FNMR .phi. (CDCl.sub.3 : DMSO-d.sub.6) = 1:2.5: -61 ppm IR .nu..sub.max.sup.KBr cm.sup.-1 : 1700(CO)31 ##STR51## .sup.19 FNMR .phi. (CDCl.sub.3): -62.5 ppm IR .nu..sub.max.sup.KBr cm.sup.-1 : 1600-1720(CO)31 fumarate ##STR52## .sup.19 FNMR .phi. (DMSO-d.sub.6 ): -60.5 ppm IR .nu..sub.max.sup.KBr cm.sup.-1 : 1700(CO)38 ##STR53## .sup.19 FNMR .phi. (CDCl.sub.3): -56.5 ppm IR .nu..sub.max.sup.KBr cm.sup.-1 : 1720(CO)38 fumarate ##STR54## .sup.19 FNMR .phi. (CDCl.sub.3, MSO-d.sub.6): -56.0 ppm IR .nu..sub.max.sup.KBr cm.sup.-1 : 1700(CO)39 ##STR55## IR .nu..sub.max.sup.CHCl 3 cm.sup.-1 : 1690(CO), 1520(NO.su b.2), 1355(NO.sub.2)39 fumarate ##STR56## ##STR57##__________________________________________________________________________

Preparation Example

Any one of the present compound (interms of active compound: 10 mg Magnesium stearate: 2 mg Hydroxypropyl cellulose: 2 mg

The above ingredients were mixed with starch to obtain 300 mg of a tablet preparation, according to a conventional tablet preparation method.

Claims

1. A dihydropyridine derivative of the formula ##STR58## wherein R.sub.1 and R.sub.2 are the same or different from each other and each denotes hydrogen, nitro, cyano, halogen, C.sub.1 -C.sub.6 alkyl, partially or fully fluorinated C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkoxy, partially or fully fluorinated C.sub.1 -C.sub.6 alkoxy, C.sub.1 -C.sub.6 alkylmercapto, C.sub.1 -C.sub.6 alkylsulfinyl or C.sub.1 -C.sub.6 alkylsulfonyl, provided that they cannot be hydrogen at the same time;

R.sub.3, R.sub.4 and

R.sub.5 denote C.sub.1 -C.sub.6 alkyl;

R.sub.6 denotes hydrogen or C.sub.1 -C.sub.6 alkyl;

R.sub.7 denotes hydrogen, C.sub.1 -C.sub.6 alkyl, phenyl C.sub.1 -C.sub.3 alkyl, halogen-substituted phenyl C.sub.1 -C.sub.3 alkyl wherein the halogen is selected from the group consisting of fluorine, chlorine, bromine and iodine as a substituent or R.sub.6 and R.sub.7 form jointly with the adjacent nitrogen atom 1,2,3-tetrahydroquinolinyl, 1,2,3-tetrahydroisoquinolinyl, or benzimidazolyl;

X denotes a group --COO--; and A denotes a C.sub.2 -C.sub.4 alkylene group, or a pharmaceutically acceptable salt thereof.

2. A dihydropyridine derivative of claim 1, wherein the derivative has the formula, ##STR59## wherein R'.sub.1 denotes methyl, chlorine, bromine, fluorine, trifluoromethyl, nitro, cyano or methoxy, R'.sub.7 denotes benzyl; and the dihydropyridine links to the 2-, 3-, or 4-position of the pyridine.

3. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(3-nitro-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

4. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(4-bromo-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

5. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(4-cyano-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

6. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(6-cyano-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

7. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(4-nitro-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

8. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(6-bromo-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

9. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(6-chloro-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

10. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(6-trifluoromethyl-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

11. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(4-trifluoromethyl-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

12. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(2-bromo-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

13. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(2-cyano-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

14. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(2-trifluoromethyl-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

15. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(5-bromo-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

16. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(6-cyano-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamine)ethyl ester 5-methyl ester.

17. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(6-nitro-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

18. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(5-nitro-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

19. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(5-trifluoromethyl-3-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

20. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(2-cyano-4-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-benzyl-N-methylamino)ethyl ester 5-methyl ester.

21. A dihydropyridine derivative of claim 2, which is 2,6-dimethyl-4-(3-trifluoromethyl-2-pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-.beta.-(N-Benzyl-N-methylamino)ethyl ester 5-methyl ester.

22. A pharmaceutical composition useful for treating vascular disorders such as coronary artery disease, cerebral artery disease, hypertension and the like, which comprises an effective amount of the dihydropyridine derivative or a pharmaceutically acceptable salt thereof of claim 1, and a diluent.

23. A dihydropyridine derivative of claim 1, wherein the partially or fully fluorinated C.sub.1 -C.sub.6 alkyl is CF.sub.3 --, CF.sub.3 CH.sub.2 -- or (CF.sub.3).sub.2 CHCH.sub.2 --.