Asymmetric Carbon-Carbon Bond Formation γ to a Carbonyl Group: Phosphine-Catalyzed Addition of Nitromethane to Allenes

A chiral phosphine catalyzes the addition of a carbon nucleophile to the gamma position of an etectron-poor allene (amide-, ester-, or phosphonate-substituted), in preference to isomerization to a 1,3-diene, in good ee and yield. This strategy provides an attractive method for the catalytic asymmetric gamma functionalization of carbonyl (and related) compounds.