Divaccinosides A–D, four rare iridoid glucosidic truxillate esters from the leaves of Vaccinium bracteatum

Abstract

Abstract Divaccinosides A–D (1–4), four rare iridoid glucoside cyclodimers in the truxillate forms, were characterized from the leaves of Vaccinium bracteatum. They were presumably biosynthesized from two known iridoid glucoside monomers, vaccinoside (5) and 10-O-trans-p-coumaroyl-6α-hydroxyl-dihydromonotropein (6), via a [2+2] cycloaddition reaction. The structures of the new compounds were established by comprehensive spectroscopic measurements, combined with chemical conversions and single crystal X-ray crystallographic analyses.