Facile synthesis of de-O-sulfated salacinols: Revision of the structure of neosalacinol, a potent α-glucosidase inhibitor

The structure of neosalacinol (8), a potent α-glucosidase inhibitor isolated recently from Ayurvedic medicine Salacia oblonga, was revised to salacinol de-O-sulfate (3c), by comparison of the spectroscopic properties of 8 with an authentic specimen synthesized by the coupling reaction of 9 and 10.