A highly efficient ultrasound-promoted synthesis of 2,3-disubstituted benzo[b]furans via intramolecular C–C bond formation in ionic liquid[bmim]BF4 at room temperature

Abstract

An efficient ultrasound-promoted synthesis of 2,3-disubstituted benzo[b]furans in the ionic liquid [bmim]BF₄ at room temperature is reported. 5-exo-dig carbanion–yne intramolecular cyclization is mediated using anhydrous K₃PO₄ as a mild, inexpensive base under atmospheric conditions giving the title benzo[b]furans in excellent yields. Ionic liquid [bmim]BF₄ has been used both as a reaction medium, as well as a catalyst for the C–C bond formation.