MAJOR SIMPLIFICATIONS IN OLIGOSACCHARIDE SYNTHESES ARISING FROM A SOLID-PHASE BASED METHOD - AN APPLICATION TO THE SYNTHESIS OF THE LEWIS-B ANTIGEN

Polymer bound glycals, upon activation by epoxidation, function as competent beta-glycosyl donors. The first glycal is linked through a silyl ether linker to a commercially available divinylbenzene polystyrene copolymer. At the end of the synthesis, soluble oligosaccharide is retrieved from the polymer by fluoridolysis. The method is self-corrective in that failed donors in a coupling step do not reemerge in the next cycle. The method is particularly powerful for creating branched sugars at C-2, a common branching site. An application of the solid phase method to a straightforward synthesis of the Lewis b antigen is described. The superiority of a diisopropylsilyl spacer relative to the previously employed diphenyl spacer is established (see compounds 4 and 5).