LIGNANS OF WESTERN RED CEDAR (THUJA PLICATA DONN): IV. THUJAPLICATIN AND THUJAPLICATIN METHYL ETHER

Abstract

In addition to the already known plicatic acid and plicatin, five new lignans have been separated by thin-layer and column chromatography from the hot-water extractive of western red cedar (Thujaplicata Donn) heartwood, and two chemical structures have been identified. These are 2-(4″-hydroxy-3″,5″-dimethoxybenzyl)-3-(4′-hydroxy-3′-methoxybenzyl)-butyrolactone (thujaplicatin methyl ether) (I) and 2-(3″,4″-dihydroxy-5″-methoxybenzyl)-3-(4′-hydroxy-3′-methoxybenzyl)-butyrolactone (thujaplicatin) (II). The former is the first known example of a lignan containing a guaiacyl and a syringyl nucleus and the first example of a syringyl-group lignan isolated from a conifer. Proof of structure by synthesis, degradation, analysis, and various spectra is presented. The other components which apparently belong to this lignan series are still being investigated.