Enantioselective C−C Bond Formation by Rhodium-Catalyzed Tandem Ylide Formation/[2,3]-Sigmatropic Rearrangement between Donor/Acceptor Carbenoids and Allylic Alcohols

摘要

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