Total Synthesis of the Natural Products Ulmoside A and (2R,3R)-Taxifolin-6-C-β-D-glucopyranoside

An efficient first total synthesis of highly polar ulmoside A and (2R,3R)-taxifolin-6-C-beta-d-glucopyranoside, useful for the prevention of metabolic disorders, has been described. Key elements of the synthesis include a Sc(OTf)(3)-catalyzed regio- and stereoselectiveC-glycosidation on taxifolin in 35% yield withd-glucose and chiral semipreparative reverse-phase high-performance liquid chromatography (HPLC) for the separation of both taxifolins and the diastereomeric mixture of taxifolin-6-C-beta-d-glucopyranosides. Correlation of the analytical data of synthetic ulmoside A and its diastereomer with a natural ulmoside A sample confirmed the assigned absolute stereochemistry of the natural products.