A mild and efficient approach for the regioselective silyl-mediated protection–deprotection of C-4 hydroxyl group on carbohydrates

A regioselective route is reported, which makes the free 4-OH group of hexopyranoses and derivatives easily and rapidly available. This protocol shows high efficiency on intermediates, such as 1a, which contain a TIPS protective group at C-6 and necessarily a benzoyl group at C-4. Treatment of 1a with TBAF cleaves the TIPS protecting group and gives rise to an intramolecular migration of the benzoyl group at C-4 to the less crowded C-6 position.