De Novo Asymmetric Syntheses of (+)-Goniothalamin, (+)-Goniothalamin oxide and 7,8-Bis-epi-Goniothalamin using Asymmetric Allylations.

A highly enantio- and diastereoselective approach to either enantiomer of (+)-goniothalamin, (+)-goniothalamin oxide and 7,8-bis-epi-goniothalamin oxide has been developed from achiral cinnamyl alcohol or cinnamaldehyde. The asymmetry of the synthesis was installed by means of a Krische or Leighton allylation. The remaining stereochemistry was installed by a diastereoselective epoxidation.