Enantioselective C-C bond formation by rhodium-catalyzed tandem ylide formation/[2,3]-sigmatropic rearrangement between donor/acceptor carbenoids and allylic alcohols

Article abstract of DOI:10.1021/ja9075293

The rhodium-catalyzed reaction of racemic allyl alcohols with methyl phenyldiazoacetate or methyl styryldiazoacetate results in a two-step process, an initial oxonium ylide formation followed by a [2,3]-sigmatropic rearrangement. This process competes favorably with the more conventional O-H insertion chemistry as long as donor/acceptor carbenoids and highly substituted allyl alcohols are used as substrates. When the reactions are catalyzed by Rh₂(S-DOSP)₄, tertiary R-hydroxycarboxylate derivatives with two adjacent quaternary centers are produced with high enantioselectivity (85-98% ee).