Efficient synthesis of oligosaccharyl 1,2-O-orthoesters from n-pentenyl glycosides and application to the pentaarabinofuranoside of the mycobacterial cell surface

Complex oligosaccharide syntheses employ the use of more than one glycosyl donor and hence, methods for the interconversion of glycosyl donors are highly valuable for the overall synthesis plan. Herein, n-pentenyl glycosides are efficiently converted to glycosyl 1,2-O-orthoesters in the presence of both acid and base sensitive functional groups. The identified protocol was found to be suitable for the synthesis of trisaccharyl and tetrasaccharyl 1,2-O-orthoester as well. Furthermore, an iterative synthesis of pentaarabinofuranoside present on the Mycobacterium tuberculosis cell surface was accomplished using this method.