Stereoselective formation of tertiary and quaternary carbon centers via inverse conjugate addition of carbonucleophiles to allenic esters

Stereoselective inverse conjugate addition of carbonucleophiles to allenoates bearing a chiral auxiliary in the ester moiety afforded optically active α,β-unsaturated carboxylic esters bearing a new stereocenter at the δ position. The rationalization of the observed selectivity was supported by semi-empirical molecular orbital calculations.