Reanalysis of lindenatriene, a building block for the synthesis of lindenane oligomers

Abstract

Lindenane oligomers isolated from Chloranthus pose significant challenges for chemical synthesis. The structure of a proposed biosynthetic monomer, lindenatriene, was recently called into question. Its attempted synthesis produced a compound whose 1H NMR spectrum differed significantly from the spectrum of a monomer produced by oligomer pyrolysis. Here we propose that the original structural assignment after pyrolysis was correct and instead the spectra of synthetic materials were misinterpreted. Reanalysis of 2D NMR data suggest that lindenatriene isomerizes (formal [1,7]-hydrogen shift) upon treatment with base.