Improved Total Synthesis of 1,3,6-Trigalloyl-β-d-glucose from Glucose

Abstract

AbstractA total synthesis of the naturally occurring 1,3,6-trigalloyl-β-d-glucose is reported. The highlights of the synthesis include a regioselective benzylation of levoglucosan, followed by a 1,6-ring opening via acetolysis. Galloyl substituents were introduced via esterification, and the mixture of anomers obtained could be fully converted into the targeted β-anomer via selective hydrazinolysis followed by activation of the anomeric position by a trichloroacetimidate of the 1′-anomeric hydroxyl group. 1,3,6-Trigalloyl-β-d-glucose and its synthetic α-anomer were obtained in an overall yield of 31% and 22%, respectively, from levoglucosan or in an overall yield of 37% of the β-isomer exclusively by recycling the α-isomer.