Studies on Nilvadipine. II. Synthesis and Structure-Activity Relationships of 2-Hydroxymethyl- and 2-Cyano-1,4-dihydropyridines Containing Heteroatom-Substituted Ester at the 5-Position.

Abstract

The synthesis of new 2-hydroxymethyl- and 2-cyano-1, 4-dihydropyridines possessing a heteroatom-substituted alkyl ester group at the 5-position of the nucleus in described. The esters were introduced via a suitable method selected from the modified Hantzsch method (method A), the hydrolysis of a chloroethyl ester obtained by method A (method B) or the replacement of the chlorine atom with various kinds of amino groups (method C). Hydroxymethyl and cyano groups at the 2-position were prepared in a similar manner to that described in a previous papare.1)The hypotensive activities of the compounds prepared in this paper were compared with the corresponding alkyl ester at the 5-position reported previously. It was found that N-benzylmethylaminoethyl esters, especially N-(4-chlorobenzyl)-and N-(3, 4-dichlorobenzyl)-N-methylaminoethyl esters, were suitable substituents at the 5-position of the 1, 4-dihydropyridine nucleus and that these substituents were somewhat more effective for hypotensive activity than simple alkyl esters in a series of 2-hydroxymethyl-1, 4-dihydropyridine derivatives. But it was found that the effect was reversed in a series of 2-cyano-1, 4-dihydropyridine derivatives. Both of them were found to be inferior to nilvadipine (1c), accepted in clinical use for the treatment of hypertension.