Radical mediated synthesis of N-acetyl-D-galactosamine containing C-disaccharides via a temporary phosphoramidic connection

The C-disaccharide {alpha-D-GalNAc-C-(1-->4)-beta-D-Glc-OMe} and its interglycosidic beta anomer were synthesized by radical coupling of phenyl 2-amino-3,4,6-tri-O-benzyl-2-deoxy-1-seleno-alpha-D-galactopyranoside onto methyl 2,6-di-O-benzyl-4-deoxy-4-C-methylene-beta-D-xylo-hexopyranoside, which are temporarily connected through a phosphoramido tether. A similar reaction was performed with methyl 2,3-di-O-benzyl-4-deoxy-4-C-methylene-alpha-D-xylo-hexopyranoside to produce the two closely related alpha-OMe C-disaccharides. (C) 1997 Elsevier Science Ltd.