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

摘要

A series of prearranged glycosides 4, 9, 14, 16, 22, 28, 33, 41, and 46, having a benzyl-protected 1-thiomannosyl donor linked through its position 6 via malonate and succinate tethers to various positions of glucosamine, galactose, mannose, and rhamnose accepters, were prepared and cyclized to the corresponding disaccharides. The configuration at the anomeric center of the 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 intramolecular glycosylations on the activation conditions and the solvent was observed. [References: 34]