Environmentally Benign Microwave-Assisted Sonogashira Preparation of Aromatic Compounds

Abstract

An efficient Sonogashira-type coupling reaction of terminal alkynes and aryl bromides by microwave activation with short reaction time under mild conditions are presented. It is illustrated herein that the traditional Sonogashira coupling reaction can be achieved with a much more efficient yet environmentally friendly condition. In contrary to the usually required 10 mol% Pd loading and the use of conventional heating at 60 °C for 24 h in order for a reaction to proceed satisfactorily, with a 100 W microwave activation, the reaction of terminal alkynes with substituted aryl bromides can be achieved with only a 2.5 mol% Pd in 10 min. The yield was improved with microwave irradiation.