Antigenic determinants of Salmonella serogroups A and D1. Synthesis of trisaccharide glycosides for use as artificial antigens.

The disaccharide glycoside 8-methoxycarbonyloctyl 4,6-O-cyclohexylidine-2-O-(tetra-O-benzyl-alpha-D-galactopyranosyl)-alpha-D-manno pyranoside (7) was used as a common intermediate to the trisaccharide determinants of both Salmonella serogroups A and D1. Acetalation of 8-methoxycarbonyloctyl alpha-D-mannopyranoside provided the 4,6-acetal derivative, which was selectively benzoylated to give the partially protected mannoside 4. Reaction of 4 with tetra-O-benzyl-alpha-D-galacto-pyranosyl chloride afforded the fully protected disaccharide, which, after transesterification, gave the selectively blocked, disaccharide glycoside (7). Addition of tyvelose by way of its 2,4-di-O-benzoyl-3,6-dideoxy-alpha-D-arabino-hexopyranosyl chloride derivative gave the blocked trisacchride determinant of Salmonella serogroup D1. 2,4,-Di-O-benzyl-3,6-dideoxy-alpha-D-ribo-hexopyranosyl chloride reacted with 7 to provide, after removal of blocking groups, the paratose-containing determinant of serogroup A.