Abstract
Iodine was explored as an efficient catalyst for the synthesis of tetrahydropyrimidines 4 and pyrrolidines 5 by a multicomponent reaction of dialkyl acetylenedicarboxylates (=dialkyl but-2-ynedioates) 1, amines 2, and HCHO 3 at room temperature (Scheme). When the molar ratios of these substrates were 1:2:4 and 1:1:4, tetrahydropyrimidines and pyrrolidines were formed, respectively. The products were obtained in high yields (7385%) within a short period of time (2535 min).