Chiral -difluoroalkyl reagents: -difluoroalkyl propargylic borons and -difluoroalkyl α-allenols.

Chiral fluorinated reagents provide new opportunities for the discovery of drugs and functional materials because the introduction of a fluorinated group significantly alters a molecule's physicochemical properties. Chiral -difluoroalkyl fragments (R-CF-C*) are key motifs in many drugs. However, the scarcity of synthetic methods and types of chiral -difluoroalkyl reagents limits the applications of these compounds. Herein, we report two types of chiral -difluoroalkyl reagents chiral -difluoroalkyl propargylic borons and -difluoroalkyl α-allenols and their synthesis by means of methods involving rhodium-catalyzed enantioselective B-H bond insertion reactions of carbenes and Lewis acid-promoted allenylation reactions. The mild, operationally simple method features a broad substrate scope and good functional group tolerance. These two types of reagents contain easily transformable boron and alkynyl or allenyl moieties and thus might facilitate rapid modular construction of chiral molecules containing chiral -difluoroalkyl fragments and might provide new opportunities for the discovery of chiral -difluoroalkyl drugs and other functional molecules.