A new synthesis of (-)-mesembrine employing sharpless AD reaction and new radical-initiated reaction

Sharpless asymmetric dihydroxylation (AD reaction) of a σ-symmetric ethyl α,α-di[(E)-2-butenyl](3,4-dimethoxyphenyl)acetate allows an asymmetric construction of a quaternary carbon center by diastereoselective formation of the γ-lactone in moderate optical yields when double dihydroxylation occurs. The lactone generated is transformed into a Sceletium alkaloid (-)-mesembrine by discovery of the unprecedented radical-initiated cleavage reaction.