Synthesis of 1,4-dihydropyridines by cyclocondensation reactions

- This review surveys the latest developments pertaining to the preparation of 1.4-dihydropyridines using Hantzsch synthesis and other cyclocondensation reactions. The chemistry of dihydropyridines (DHP) up to the year 1980 had been reviewed i n several surveys of literature1-3. Among the different isomers, 1.4-DHP merits special attention, the interest i n these compounds increasing progressively. Investigations along these lines include the synthesis of model compounds NAD(P)H-analogues o f 1.4-dihydronicotinamide - and their involvement i n hydrogen transfer reactions. Recently, several review papers have appeared on the subject4-' including the transfer o f hydrogen and other groups by chiral DHP~". Another big issue i s the application of 1.4-DHP i n medicine and industry. These compounds are chiefly obtained by using various modifications o f Hantzsch synthesis. Most extensively studied are the calcium antagonists, whose synthesis1' and properties11-13 have been treated i n a number o f reviews. Several papers describe investigations of individual drugs14-l6 such as vasodilators and antihypertensive remedies - nifedipine, nitrendipine. Calcium transport agonists have been also found among ~ , ~ - D H P ' ~ - ~ ' . 1.4-MP possess antioxidant 21-26 (diludin i s routinely usedZ7), h e p a t o p r o t e ~ t i v e ~ ~ - ~ ~ . antit~mour'~-'~, antimutagenic'" geroprotec-tive3', antiatheros