Construction of 3,6-Anhydrohexosides via Intramolecular Cyclization of Triflates and Its Application to the Synthesis of Natural Product Isolated from Leaves of Sauropus rostratus

A novel synthetic approach to construct various 3,6-anhydrohexosides via an intramolecular cyclization of corresponding triflates is described. The nucleophilic attack from C3 p-methoxybenzylated hydroxyl to C6 trifluoromethanesulfonate on triflate structures triggered the cyclization reaction to provide 3,6-anhydrohexosides in excellent yields, making the strategy more efficient with respect to the reported protocols. By applying this methodology, a concise first total synthesis of natural product isolated from leaves of Sauropus rostratus was accomplished.