Three Novel Sequential Reactions for the Facile Synthesis of a Library of Bisheterocycles Possessing the 3-Aminoimidazo[1,2-a]pyridine Core Catalyzed by Bismuth(III) Chloride

Abstract

Novel, one-pot, two-step, sequential protocols for the synthesis of 1,4-phenylene bisheterocyclic compounds have been developed. Successive sequencing of the Groebke–Blackburn–­Bienaymé reaction with Ugi-azide, Hantzsch and Biginelli reactions results in rapid and efficient formation of bisheterocyclic compounds. A simple, fast and high yielding method for the synthesis of 3-aminoimidazo[1,2-<i>a</i>]pyridines catalyzed by bismuth(III) chloride under solvent-free conditions is reported. Bismuth(III) chloride is also an efficient catalyst for the Ugi-azide reaction under solvent free conditions.