Regiocontrolled Synthesis of Enantiopure 3, 3 -Thiosubstitued Biphenyls

The synthesis of naked ellagitannin analogous, having a preferred sense of twist of the diphenyl moiety, with a rhamnose and a glucose template is reported. A clear induction in the chirality of diphenyl moiety, mediated through a 10-membered ring via ester linkages, was observed. The chiral scaffold of glucose (diequatorial 2,3-hydroxyl groups) exerts a remarkable stronger atropdiastereoselective effect onto the diphenoyl group than the rhamnose ring (axial-equatorial 2,3-hydroxyl groups), according to Schmidt-Haslam hypothesis.