Para-chlorobenzyl protecting groups as stabilizers of the glycosidic linkage: Synthesis of the 3′-O-sulfated Lewis x trisaccharide
摘要:
The 3'-0-sulfated trisaccharide Lewis x (1) and unsulfated Lewis x (2) have been synthesized using a mute that highlights a more facile regioselective benzylidene ring-opening procedure and the employment of chlorobenzyl groups as a way of strengthening the acid-labile alpha-fucose linkage. (C) 1997 Elsevier Science Ltd.
Kohlenhydrat-Bausteine zum Aufbau Tumor-assoziierter Antigene. Synthese von Lewis Y-Determinanten
摘要:
The synthesis of the ethoxycarbonyloctanyl glycoside of the Lewis-Y (Le(y)) tetrasaccharide, a part of complex glycosphingolipids, was based on the trichloroacetimidate method for glycoside synthesis. The regioselective introduction of protective groups and the high yield of epimers of the azidonitration reaction applied to O-(2,3,4-tri-O-acetyl-6-0-[dimethyl-(2,3-dimethyl-2-butyl)silyl]-beta-D-galactopyr-anosyl}-(1 --> 4)-3-0-acetyl-1,5-anhydro-6-0-[dimethyl-(2,3-dimethyl-2-butyl)silyl]-D-arabino-hex-1-enitol led to a lactosamine acceptor molecule. The double specific introduction of an alpha-L-fucosyl group in high yield gave a protected Le(y)-tetrasaccharide. After activation to give the alpha-trichloroacetimidate, specific beta-glycosylation with 8-ethoxycarbonyl octanol under S(N) 2 condition, followed by cleavage of all protective groups led to the tetrasaccharide, alpha-L-Fuc p-(l --> 2)-beta-D-Gal p-(1 --> 4)-[alpha-L-Fuc p-(l --> 3)]-beta-D-Glc pNAcO(CH2)8CO2Et in high yield.
[EN] PROCESS FOR THE SYNTHESIS OF L-FUCOSYL DI- OR OLIGOSACCHARIDES AND NOVEL 2,3,4 TRIBENZYL-FUCOSYL DERIVATIVES INTERMEDIATES THEREOF<br/>[FR] PROCÉDÉ DE SYNTHÈSE DE DISACCHARIDES OU D'OLIGOSACCHARIDES DE L-FUCOSYLE ET DE NOUVEAUX INTERMÉDIAIRES DE CEUX-CI DU TYPE 2,3,4-TRIBENZYLFUCOSYLE