Transition metal-mediated C═O and C═C bond-forming reactions: a regioselective strategy for the synthesis of imidazo[1,2-a]pyridines and imidazo[1,2-a]pyrazines.

A novel and convenient transformation for the regiospecific synthesis of functionalized imidazo[1,2-a]pyridine aldehydes/ketones and 3-vinyl imidazo[1,2-a]pyridines has been developed via copper(I)- and palladium(II)-catalyzed cyclization. The one-pot reaction proceeds smoothly with commercially available catalysts and affords the products in moderate to good yields. It represents an efficient approach for the formation of C-N, C═O, and C═C bonds under mild conditions.