Facile Synthesis of Novel Hexahydroimidazo[1,2-a]pyridine Derivatives by One-Pot, Multicomponent Reaction under Ambient Conditions

An efficient one-pot multicomponent reaction for the synthesis of novel tetrasubstituted hexahydroimidazo[1,2-a]pyridines starting from readily available cinnamaldehydes, ethylenediamines, and 1,3-dicarbonyl compounds catalyzed by AcOH is described. Two new cycles and four new bonds are constructed with all reactants being efficiently utilized in this transformation. The products could be obtained in 1–3 h under ambient conditions exclusively as a single isomer (trans). Single-crystal X-ray analysis confirmed the trans derivative as the only isomer.