Ligand-Controlled Copper-Catalyzed Highly Regioselective Difluoromethylation of Allylic Chlorides/Bromides and Propargyl Bromides

Highly regiodivergent copper-catalyzed allylic/propargylic difluoromethylation reactions by employing different ligands are described. When 5,6-dimethyl-1,10-phenanthroline was used as the ligand, exclusively -difluoromethylated products were obtained, while -selective difluoromethylated products were generated when N-heterocyclic carbene-SIPr was used as the ligand. Likewise, high - vs. -selectivities were achieved in the presence of similar copper catalysts for the reactions of propargyl bromides. Moreover, a copper-catalyzed asymmetric allylic difluoromethylation reaction with moderate to good enantioselectivity by the use of chiral ligands was developed.