A facile preparation of peracylated alpha-aldopyranosyl chlorides with thionyl chloride and tin tetrachloride.

Aldopyranose peracetates react with thionyl chloride and tin tetrachloride, producing the corresponding peracylated aldopyranosyl chlorides in very good to excellent yields (88-100%) with exclusive alpha-anomeric selectivity and short reaction times. The use of peracylated sugars as the substrate in large scale reactions also proceeds in high yield.