SYNTHESIS OF TA-D-GLCPNAC-(1-]2)-ALPHA-D-MANP-(1-]O)(CH2)(7)CH3 PROBES FOR EXPLORATION OF THE SUBSTRATE-SPECIFICITY OF GLYCOSYLTRANSFERASES.2. HEX=3-O-METHYL-BETA-D-GAL, 3-DEOXY-BETA-D-GAL, 3-DEOXY-3-FLUORO-BETA-D-GAL, 3-AMINO-3-DEOXY-BETA-D-GAL, BETA-D-GUL, ALPHA-L-ALT, OR BETA-L-GAL

Seven analogues of the trisaccharide beta-D-Galp-(1 --> 4)-beta-D-Glcp NAc-(1 --> 2)-alpha-D-Manp-(1 --> O)(CH2)(7)CH3 have been synthesized as potential substrates for glycosyltransferases involved in the chain -termination of N-acetyllactosamine-type N-glycans. These compounds in clude: 3-O-methyl-beta-D-Galp-(1 --> 4)-beta-D-GlcpNAc-(1 --> 2)-alpha -D-Manp-(1 --> O)(CH2)(7)CH3, 3-deoxy-beta-D-Galp-(1 --> 4)-beta-D-Glc pNAc-(1 --> 2)-alpha-D-Manp-(1 --> O)(CH2)(7)CH3, 3-deoxy-3-fluoro-bet a-D-Galp-(1 --> 4)-beta-D-GlcpNAc-(1 --> 2)-alpha-D-Manp-(1 --> O)(CH2 )(7)CH3, 3-amino-3-deoxy-beta-D-Galp-(1 --> 4)-beta-D-GlcpNAc-(1 --> 2 )-alpha-D-Manp-(1 --> O)(CH2)(7)CH3, beta-D-Gulp-(1 --> 4)-beta-D-Glcp NAc-(1 --> 2)-alpha-D-Manp-(1 --> O)(CH2)(7)CH3, beta-L-Galp-(1 --> 4) -beta-D-GlcpNAc-(1 --> 2)-alpha-D-Manp-(1 --> O)(CH2)(7)CH3, and alpha -L-Altp-1(1 --> 4)-beta-D-GlcpNac-(1 --> 2)-alpha-D-Manp-(1 --> O)(CH2 )(7)CH3. All trisaccharides were obtained by condensation of suitably modified glycosyl donors based on imidates or thioglycosides with the same disaccharide acceptor, octyl do-beta-D-glycopyranosyl)-alpha-D-ma nnopyranoside, followed by deprotection. (C) 1997 Elsevier Science Ltd .