partial O -deacylation of fully acylated methyl glycosides and some other glycosyl compounds (23 compounds) was found to be induced, to give, in good yields, products bearing one free hydroxyl group; the results obtained indicated that, among the primary and secondary O -acyl groups, the 2- O -acyl groups were, in general, the most labile toward the nucleophile (hydrazine). Hydrazinolysis of 1,2- O -