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 γ-lactones. Sequential alkylation and reductive alkylation furnished the α-quaternary-β-ternary substituted γ-lactone derivative as a ≥10:1 mixture of diastereoisomers.