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An investigation is undertaken into the propensity of glycosyloxazolines to undergo reductive cleavage by catalytic hydrogenation.Results indicate that the protecting groups on carbohydrate hydroxylgroups modulate the rate of glycosyl oxazoline reduction; electron-withdrawingester groups curtail reaction so that reductive cleavage of benzylethers and esters, or reduction of azide elsewhere in the moleculemay be readily achieved.

The regioselectivity of glycosylation of MANNO and GLUCO acceptor diols possessing free hydroxyl groups at the 4- and 6-positions is found to be strongly dependent on functionalization of the 3-hydroxyl group. Surprisingly, highly regioselective glycosylation of the more hindered 4-hydroxyl can be readily achieved in the presence of the primary 6-hydroxyl in cases where the 3-hydroxyl of the acceptor is protected as a benzyl ether and when the donor possesses an ester participating group at the 2-position. However, reverse regioselectivity, namely glycosylation of the 6-hydroxyl, is observed when the 3-hydroxyl has been previously glycosylated.