Total Syntheses, Absolute Configurations, and Cytotoxicity Evaluation of Ugonstilbenes A, B, and C from the Rhizomes of Helminthostachys zeylanica.

ABSTRACT

This study describes the first and efficient syntheses of the naturally occurring ugonstilbenes A, B, and C. The stilbene skeleton was prepared using the Horner-Wadsworth-Emmons reaction. On the basis of their specific rotations, the absolute configurations of ugonstilbenes A and C were both determined to be R, while the absolute configuration of ugonstilbene B was determined as 4aS,9aR. The synthesized compounds showed cytotoxic activities against selected human cancer cell lines.