Total synthesis of (+)-galanthamine starting from D-glucose

The stereoselective total synthesis of (+)-galantbamine (+)-1 starting from D-glucose is described. The cyclohexene ring in (+)-1 was prepared in an optically active form from D-glucose using Ferrier's carbocyclization reaction, and the critical quaternary carbon was stereoselectively generated via chirality transfer based on the Claisen rearrangement of a cyclohexenol. The dibenzoftiran skeleton was effectively constructed by the bromonium ion-mediated intramolecular cyclization of a cyclohexene possessing a phenolic ether function. After the introduction of a carbon-carbon double bond, the Pictet-Spengler type cyclization, followed by the reduction of the amide function completed the chiral synthesis of (+)-1. (c) 2007 Elsevier Ltd. All rights reserved.