Recent developments in catalytic, asymmetric α-halogenation:: A new frontier in asymmetric catalysis

The development of milder and more sophisticated halogenating reagents that offer significantly greater chemoselectivity and stereocontrol than diatomic halides has been critical to the realization of asymmetric a-halogenation. Within the past few years several groups have reported catalytic, enantioselective methods for a-halogenation achieved by utilizing the catalytic generation of either enolates (zwitterionic or metal-based charge delocalized) or enamines. Most importantly, this recent work has greatly enhanced the synthetic utility of organic halogenations and, in doing so, opened up a promising new frontier in organic synthesis. This microreview presents recent advances in the area of catalytic, asymmetric alpha-halogenations of carbonyl compounds. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).