Facilitating the Transmetalation Step with Aryl-Zincates in Nickel-Catalyzed Enantioselective Arylation of Secondary Benzylic Halides
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A method for the highly enantioselective construction of fluoroalkyl-substituted stereogenic center by a nickel-catalyzed asymmetric Suzuki-Miyaura coupling of a-bromobenzyl trifluoro-/difluoro-/monofluoromethanes with a variety of lithium organoborate in the presence of 1.0 equivalent of ZnBr2 was described. Preliminary mechanistic studies disclosed that reaction of lithium organoborate with ZnBr2 generated a zincate [Ph2ZnBr]Li, which facilitates the transmetallation step of the nickel-catalyzed cross-coupling reaction to enable high enantioselectivity.