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.
Acyl Group Migration in Pyranosides as Studied by Experimental and Computational Methods
have studied the acyl migration in different monosaccharides using five different acylgroups by a combination of experimental, kinetic and theoretical tools. The results show that the anomeric configuration in the monosaccharide has a major influence on the migration rate, together with the relative configurations of the other hydroxylgroups and the nature of the migrating acylgroup. Full mechanistic