Facile synthesis of conjugated exo-glycals

Two efficient methods were explored for the synthesis of various conjugated exo-glycals: (i) by nucleophilic addition of sugar lactones with a subsequent dehydration, and (ii) by selenylation of C-glycosides with a subsequent selenoxide elimination. These reactions occurred in a stereoselective manner to give exclusively or predominantly the (Z)-isomers of exo-glycals. (C) 2001 Elsevier Science Ltd. All rights reserved.