SYNTHETIC STUDIES IN CARBOHYDRATES .83. SYNTHESIS OF OLIGOSACCHARIDES CONTAINING THE X-ANTIGENIC TRISACCHARIDE (ALPHA-L-FUCP-(1-]3)-[BETA-D-GALP-(1-]4)]-BETA-D-GLCPNAC) AT THEIR NONREDUCING ENDS

The ''armed'' methyl 2,3,4-tri-O-benzyl-1-thio-beta-L-fucopyranoside was reacted with ''disarmed'' phenyl O-(tetra-O-acetyl-beta-D-galactopyranosyl)-(1 --> 4)-6-O-benzyl-2-deoxy-2-phthalimido-1-thio-beta-D-glucopyranoside in the presence of CuBr2-Bu4NBr complex to give phenyl O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl) (1 --> 4)-O-[(2,3,4-tri-O-benzyl-alpha-L-fucopyranosyl)-(1 --> 3])-6-O-benzyl-2-deoxy-2-phthalimido-1-thio-beta-D-glucopyranoside (6)as a novel glycosyl donor. The glycosylating capability of 6 was further examined using N-iodosuccinimide-triflic acid as a reagent. This led to the synthesis of a tetrasaccharide and a pentasaccharide incorporating the X-antigenic structure represented by 6.