New and efficient palladium(0)-mediated microwave-assisted direct C3 alkenylation of imidazo[1,2-a]pyridines

In this paper, we present the synthesis of 3-alkenylimidazo[1,2-a]pyridines in high to moderate yields by microwave direct palladium-catalyzed C-H alkenylation between bromoalkenes and imidazo[1,2-a]pyridines. The scope and limitation of the palladium(0)-catalyzed alkenylation method were investigated. Optimized conditions were successfully applied to a wide variety of imidazo[1,2-a]pyridine derivatives and bromoalkenes. The compatibility of the synthesis with the presence of a chloro substituent in the 6-position was investigated. The 6-chloroimidazo[1,2-a]pyridines were functionalized using Suzuki cross-coupling conditions to give polyfunctional compounds.