Organocatalytic enantioselective one-pot synthesis and application of substituted 1,4-dihydropyridines - Hantzsch Ester analogues

An easy and simple one-pot approach for the formation of optically active substituted I.,4-dihydropyridines by using asymmetric organocatalysis is presented. The one-pot reaction of alpha,beta-unsaturated aldehydes with beta-diketones or beta-ketoesters and primary amines gives optically active 2,3-substituted 1,4-dihydropyridines in moderate yields and with enantioselectivities up to 95 % ee. It is also demonstrated that the optically active 1,4-dihydropyridines can be used in situ for the direct enantioselective reduction of, for example, alpha-ketoesters with high enantioselectivity.