Thiamine Hydrochloride-Catalyzed One-Pot Synthesis of 1,4-Dihydropyridine Derivatives Under Solvent-Free Conditions

[image omitted] An efficient one-pot synthesis of 1,4-dihydropyridines from an aldehyde, -keto ester, and ammonium acetate or formamidine acetate using thiamine hydrochloride (VB1) as the catalyst under solvent-free conditions at ambient temperature is described. All types of aldehydes, including aromatic, aliphatic, and unsaturated aldehydes, give good yields. The catalyst can easily be recovered after completion of the reaction and reused without affecting its activity.