Asymmetric [2,3]-Wittig rearrangement as a general tool for asymmetric synthesis

Recent advances in the asymmetric [2,3]-Wittig rearrangement as a general tool for asymmetric synthesis of homoallylic alcohols are described. First, the synthetic utilities of the asymmetric transmission type and the two asymmetric induction types are demonstrated, including applications in asymmetric syntheses of natural products and steroid side chains. Second, some examples are presented of the enantioselective versions involving a chiral ligand-bound boron enolate and organolithium as the migrating terminus. Finally, the mechanistic grounds of the asymmetric versions are discussed on the basis of the stereochemical analyses of the asymmetric version involving an enantiomerically-defined carbanion terminus.