Isolation of a new disaccharide nucleoside from Helleborus caucasicus: structure elucidation and total synthesis of hellecaucaside A and its β-anomer

Hellecaucaside A, a new disaccharide nucleoside featuring a 2'-O-alpha-D-ribofuranosyluridine skeleton and a 4-hydroxybenzoyl group at the 50 position, was isolated from the underground part of Helleborus caucasicus. The structure of the compound was elucidated by means of chemical degradation and spectroscopic analyses, such as 1D/2D NMR, chiral-GC, and HRMS. The total synthesis of hellecaucaside A and its beta-anomer was accomplished, unequivocally confirming the structure of the natural product. (C) 2014 Elsevier Ltd. All rights reserved.