Synthesis of flavones via the Stork–Danheiser reaction

Abstract

A new method to access flavones in a convergent fashion has been developed, based on the Stork–Danheiser reaction. By this method, 4-methoxy coumarins are allowed to react with organolithium at low temperatures (−78 °C to −40 °C) and then acidic workup gives the desired flavones in 18–86% yields. This method features transition metal-free conditions, readily available starting materials, and simple operation. It is particularly efficient when rapid generation of B ring flavone derivatives is desired.