PURPOSE: To advantageously glycosylate hydroxyl groups of a sugar anomer in good yield of glycosides in a small number of reaction steps, by reacting the above-mentioned hydroxyl groups with a specific thiocarbonate to directly thioglycosylate the anomer groups and then reacting the resultant groups with other sugars.

CONSTITUTION: The hydroxyl groups of a sugar anomer are reacted with S,S'-bis(1-phenyl-1H-tetrazol-5-yl)dithiocarbonate to directly thioglycosylate the anomer groups. The resultant groups are then reacted with other sugars to carry out glycosylation.