Prearranged glycosides Part 13 - Intramolecular mannosylations of glucosamine, galactose, mannose, and rhamnose derivatives via prearranged glycosides

A series of prearranged glycosides 4, 9, 14, 16, 22, 28, 33, 41, and 46, ha ving a benzyl-protected 1-thiomannosyl donor linked through its position 6 via malonate and succinate tethers to various positions of glucosamine, gal actose, mannose, and rhamnose accepters, were prepared and cyclized to the corresponding disaccharides. The configuration at the anomeric center of th e products strongly depended on the position of the tt ther in the acceptor part and could be predicted from the calculated thermodynamic stability of the products. No strong dependence of the diastereoselectivity of the intr amolecular glycosylations on the activation conditions and the solvent was observed.