Induction of a Preferred Sense of Twist in Flexible Diphenyls by Carbohydrate Scaffolds. Synthesis of Two 'Naked' Ellagitannin Analogous

The synthesis of “naked ” ellagitannin analogues 1 and 2, 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 the 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 the Schmidt−Haslam hypothesis.