Ultrasound-assisted metal-mediated method for the formation of tetrahydro-3,30-disubstituted biscoumarins

Abstract

A new method for faster and simple preparation of 3,30,4,40-tetrahydro-3,30-disubstituted-4,40-biscoumarins with participation of an organozinc reagent is reported. The reaction is promoted by ultrasound irradiation and it offers a simple experimental setup and excellent reproducibility of the results. Moreover, homodimers were isolated in yields of 45-92%. The dimerization conditions are applicable to coumarins with electron-withdrawing groups at third position.