Baeckeins A and B, Two Novel 6‐Methylflavonoids from the Roots of Baeckea frutescens

Abstract

AbstractA pair of novel isomeric 6‐methylflavonoids, named baeckeins A (1) and B (2), were isolated from the roots of Baeckea frutescens. The two compounds possess a unique C23 skeleton, resulting from the 6‐methylation and 8‐arylation of a flavonol (=3‐hydroxy‐2‐phenyl‐4H‐1‐benzopyran‐4‐one) framework and the formation of an unusual lactone ring E. Their structures were elucidated by detailed spectroscopic analyses, including HR‐ESI‐MS and 1D‐ and 2D‐NMR data (HSQC, HMBC, and ROESY). A plausible biogenetic pathway for compounds 1 and 2 is also proposed (Scheme).