Flavonoid epoxides. Part 16. Synthesis and base-catalysed rearrangement of aurone epoxides

A number of new aurone epoxides have been synthesised by an improved method of alkaline hydrogen peroxide epoxidation of aurones. Flavonols were the main products when the reaction period was prolonged. Aurone epoxides on reaction with base rearranged to flavonols and to aroylcoumaran-3-ones. Aurone epoxides may also be synthesised by the Darzens condensation.