Novel stereoelectronic behavior of bicyclic glycosyl donors: Application to the synthesis of both 2-deoxy-alpha- and -beta-glycosides

Two pairs of novel stereoisomeric, cyclic glycosyl donors exhibit different behaviors in glycosylation processes. In the pair of alpha-gluco (1) and b eta-manno (2), the former exhibits reversability with its glycoside product whereas the latter does not. In the alpha-gluco (3) and beta-manno (4) set , the former undergoes glycosyl transfer via an isolable intermediate where as the latter does not. The differing anomeric effects of exerted in the gr ound states are proposed as the force which explains the differences in beh avior.