[reaction: see text] The selective removal from carbohydrate substrates of methoxy protectinggroups next to hydroxy groups is reported. On treatment with PhI(OAc)(2)-I(2), the methoxy group is transformed into an easily removable acetal. The mild conditions of this methodology are compatible with many functional groups, and good to excellent yields are usually achieved.
The selective cleavage of methoxy protectinggroups next to hydroxy groups is achieved using a radical hydrogen abstraction reaction as the key step. Under the reaction conditions, the hydroxy group generates an alkoxyl radical that reacts with the sterically accessible adjacent methoxy group, which is transformed into an acetal. In the second step, the acetals are hydrolyzed to give alcohols or diols