One-step, three-component synthesis of pyridines and 1,4-dihydropyridines with manifold medicinal utility

Privileged medicinal scaffolds based on the structures of 2-amino-3,5-dicyano-6-sulfanylpyridines and the corresponding 1,4-dihydropyridines have been prepared via a single-step, three-component reaction of structurally diverse aldehydes with various thiols and malononitrile. Mechanistic studies revealed that 1,4-dyhidropyridines undergo oxidation by the intermediate Knoevenagel adducts rather than by air oxygen. Although the latter process undermines the yields of pyridines, it results in the formation of substituted enaminonitriles, promising antiinflammatory agents.