I2/DMSO-Enabled Cascade Michael Addition/Oxidative Cyclization: Access to Imidazo[2,1-b][1,3,4]thiadiazoles

Abstract

A straightforward protocol for accessing imidazo[2,1-b][1,3,4]thiadiazoles via I2-catalyzed tandem Michael addition-oxidative cyclization has been developed. Three-component approach to access imidazo[2,1-b][1,3,4]thiadiazoles from hydrazone, chalcone, and KSCN has been demonstrated. Both I2 and DMSO are essential and the reaction progressed through a radical pathway. The strategy is also extendable towards the synthesis of imidazo[1,2-a]pyridine and benzo[d]imidazo[2,1-b]thiazole derivatives. Wide functional group tolerances, the use of simple and unfunctionalized building blocks and inexpensive catalyst, large-scalability, and easy execution are the notable features of this approach.