合成路线1

The intermediate thioglycoside (V) is prepared as follows. Esterification of maltotriose (I) with acetic anhydride and sodium acetate provides peracetate (II). Subsequent reaction of (II) with ethanethiol in the presence of boron trifluoride etherate yields the ethyl thiopyranoside (III). Removal of the acetate esters of (III) is effected by methanolysis in the presence of potassium tert-butoxide, yielding (IV). Then, reesterification of (IV) by means of benzoyl chloride and pyridine furnishes the target intermediate (V).