Asymmetric synthesis of S-(-)-cucurbitine

Article abstract of DOI:10.1016/S0040-4039(00)61768-9

The asymmetric synthesis of (S)-(-)-cucurbitine in greater than 98% ee is described. The key step of the synthesis involves 1,3-dipolar cycloaddition of azomethine ylide (1) to α,β-dehydrolactone (3) to give pyrrolidine (6) as a single diastereomer.