Asymmetric Total Syntheses of (-)-Lycoramine, (-)-Lycoraminone, (-)-Narwedine, and (-)-Galanthamine.

A concise asymmetric total synthesis of naturally occurring Amaryllidaceae alkaloids sharing dihydrobenzofuran scaffolds, (-)-galanthamine ( 1a ), (-)-lycoramine ( 1b ), (-)-narwedine ( 2a ), and (-)-lycoraminone ( 2b ), is reported. Orthoester Johnson-Claisen rearrangement of allyl alcohol (+)- 9 (98% ee) in diisopropylethylamine furnished enantioenriched cyclohexene (+)- 8 (97.4% ee) with a quaternary stereogenic center.