PURPOSE: To simply obtain the subject compound useful as a synthetic intermediate for antibiotics, etc., in high yield by reacting a specific hydroxysaccharide with a hydroxy compound or mercapto compound in the presence of a bivalent tin compound and an N-haloimide compound.

CONSTITUTION: (A) 1-Hydroxysaccharide in which functional groups at other positions than 1 position are protected {e.g. a compound of formula I [R1 is H, a lower alkoxy, etc.; R4 is H or CH2OR5; R2, R3 and R5 are each protecting groups, (substituted)alkyl or sugar whose hydroxyl groups, etc., are protected by protecting groups]} is made to react with (B) a hydroxy compound or mercapto compound [e.g. (substituted)alkanol or (substituted)alkylmercaptane] in the presence of a bivalent tin compound (e.g. SnF2 or SnCl2) and an N- haloimide compound (e.g. halogenated succinic acid) to provide the objective compound (e.g. a compound of formula II). Furthermore, the component B is used in an equivalent weight of 0.9-4.0, preferably 1.1-2.0 based on the component A.