Total Synthesis of Ellagitannins through Regioselective Sequential Functionalization of Unprotected Glucose

Short total syntheses of natural glycosides (ellagitannins) were performed through sequential and regioselective functionalization of the hydroxy groups of unprotected glucose. The key reactions are β-selective glycosidation of a gallic acid derivative by using unprotected glucose as a glycosyl donor and catalyst-controlled regioselective introduction of a galloyl group into the inherently less reactive hydroxy group of the glucoside.