Formal synthesis of (−)-morphine from d-glucal based on the cascade Claisen rearrangement

The chiral and stereoselective synthesis of (−)-dihydroisocodeine 2, the known synthetic intermediate of (−)-morphine 1, is described. The vicinal tertiary and quaternary stereocenters in 2 were effectively generated in one-step reaction based on the cascade sequential Claisen rearrangement of a cyclohexene-diol derived from d-glucal.