Ga(OTf)3-promoted synthesis of functionalized 2-carbonyl-imidazo[1,2-a]pyridines derived from ethyl α-benzotriazolyl-α-morpholinoacetate

An efficient route to the synthesis of 3-amino-2-ethoxycarbonyl imidazo[1,2-a]pyridine derivatives starting from ethyl α-benzotriazolyl-α-morpholinoacetate has been developed. By the reactions between primary heterocyclic amidines and isocyanides catalyzed by Ga(OTf)3, target compounds were obtained in moderate to good yields. This in turn will set the stage for the wide application of this useful reaction for the synthesis of 3-amino-2-carbonylimidazo[1,2-a]pyridines based on imidazo[1,2-a]pyridine privileged structures.