The absolute configuration of 1-(3',4'-dihydroxycinnamoyl)cyclopentane-2,3-diol from the amazonian tree Chimarrhis turbinata.

ABSTRACT

An antioxidant, 1-(3',4'-dihydroxycinnamoyl)cyclopentane-2,3-diol [or (E)-2,3-dihydroxycyclopentyl-3-(3',4'-dihydroxyphenyl)acrylate (1)], and two known trans- and cis-chlorogenic acid methyl esters were isolated from the ethanolic extract of the leaves of Chimarrhis turbinata. The relative configuration of 1 was determined by NMR and by comparison of the circular dichroic spectrum (CD) with those of the enantiomers of synthetic 3',4'-dimethoxycinnamoyl analogues. The absolute configuration of one of the synthetic enantiomers was determined using the CD exciton chirality method. This established the structure of naturally occurring 1 as (E)-2,3-dihydroxycyclopentyl-3-(3',4'-dihydroxyphenyl)acrylate.