Method Development in the Regioselective Glycosylation of Unprotected Carbohydrates

Project 1: Tin-mediated glycosylation of unprotected hexopyranosides The regioselective glycosylation at the 6 position in 2,3,4,6-unprotected hexopyranosides has been investigated with dibutyltin oxide as the directing agent. Perbenzylated hexopyranosyl bromides were employed as the donors and the glycosylations were promoted by tetrabutylammonium bromide.

The couplings were completely selective and gave rise to a number of 1,6-linked disaccharides with 1,2- cis-linked orientation. Project 2: Boron-mediated glycosylation of unprotected carbohydrates Boron-mediated regioselective Koenigs-Knorr glycosylation has been studied with unprotected acceptors. By means of organoboron derivatives, cis-diols in acceptors can be either activated or masked via an ester formation.