Rhodium(I)/(-)-DIOP Catalyzed Regio- and Enantioselective Addition of Carboxylic Acids to Allenes

Breit et al. have reported the first intermolecular regio- and enantioselective addition of carboxylic acids to terminal allenes to form branched allylic esters, employing a Rh(I)/(-)-DIOP catalyst system. Even 1,1-disubstituted allenes could be employed, leading to the formation of a quaternary chiral center. They have proposed the reaction proceeds through the Rh-π-allyl complex from the results of labeling experiments using deuterated benzoic acid.