Enantioselective [2,3]-Sigmatropic Rearrangements: Metal-Bound or Free Ylides as Reaction Intermediates?

Out of bounds: Enantioselective rearrangement reactions are a long-standing challenge in organic synthesis. Recent advances are highlighted that led to the development of the first enantioselective Doyle-Kirmse reaction and enantioselective rearrangement reactions of iodonium ylides.