Absolute Configuration of Resveratrol Oligomers Isolated from Hopea utilis

Abstract

Phytochemical studies on a stem of Hopea utilis (Dipterocarpaceae) resulted in the isolation of two new resveratrol derivatives, namely hopeaside E (1; resveratrol trimer) and hopeaside F (2; resveratrol pentamer), together with ten known resveratrol derivatives, 3-12. The structures of the new compounds were elucidated by spectroscopic analyses, including NMR experiments, and their absolute configurations were determined on the basis of a comparative configurational analysis using the β-D-glucopyranosyl group and chiroptical data. The absolute configuration of (+)-balanocarpol (3) was also determined by acid-catalyzed skeletal conversion.