Metal-Free Difunctionalization of Pyridines: Selective Construction of N -CF 2 H and N -CHO Dihydropyridines.

The reactivity of N -difluoromethylpyridinium salts is seldom explored because of their instability and low availability. Here we present a novel nucleophilic addition of N -difluoromethylpyridinium salts with nitroalkanes to synthesize N -CF ₂ H-dihydropyridines and N -CHO-dihydropyridines in a highly efficient and regioselective pathway. This protocol exhibits good functional group tolerance and good to excellent yields.