Enantiospecific and regioselective rhodium-catalyzed allylic alkylation: diastereoselective approach to quaternary carbon stereogenic centers.

The enantiospecific and regioselective rhodium-catalyzed allylic alkylation of a series of chiral nonracemic allylic carbonates, followed by ozonolysis and reductive lactonization, provides a convenient route to optically active gamma-lactones. Sequential alkylation and reductive alkylation furnished the alpha-quaternary-beta-ternary substituted gamma-lactone derivative as a >/=10:1 mixture of diastereoisomers.