AN EZOMYCIN MODEL GLYCOSYLATION

A model glycosylation reaction for application to the synthesis of the ezomycin class of antibiotics is described. The ezoaminuroic thioglyc oside donor 13, with a reduced and protected C-6 position and trifluor oacetamide at C-3, was prepared from the Cerny epoxide 7 by a nine-ste p procedure. The model D-pulo-pyranoside acceptor 20, which closely re sembles an actual acceptor in the vicinity of the reacting axial hydro xyl, was synthesized from methyl beta-D-galactopyranoside 14. Glycosyl ation with N-iodosuccinimide/triflic acid as promoter gave the disacch aride 21 in 90% yield.