Our initial efforts were directed toward the removal of silyl protecting groups from the carbohydrate building blocks by using HClO 4 ·SiO 2 . For example, to a solution of compound 1 in acetonitrile 20 mol % HClO 4 ·SiO 2 was added and the mixture was stirred for 1.5 h. But interestingly, beside the expected desilylated product 1b (88%), 1,6-anhydro sugar 1a (8%) was obtained as well (Scheme 1). This observation inspired us to try the preparation of 1,6-anhydro sugars by ...
