1 , 4 - dihydropyridines bearing carbonyl functions in the 3 - and 5 - positions , being optionally substituted by lower alkyl in the 6 - position , being substituted in the 4 - position by lower alkyl , phenyl , substituted phenyl or a heterocyclic group , and being fused through the 1 - and 2 - positions to a five , six or seven membered cycloalkyl ring , one methylene group of which can be replaced by sulfur , oxygen imino or alkylimino , are antihypertensive agents and coronary vessel dilators . the compounds , of which 6 - methyl - 4 -- 1 , 2 - pentamethylene - 1 , 4 - dihydropyridine - 3 , 5 - dicarboxylic acid 3 , 5 - diethyl ester is a representative embodiment , are prepared through condensation of an ylideneacetoacetic acid ester and a cyclic enamino carbonyl derivative .