Copper(i) catalyzed Sonogashira reactions promoted by monobenzyl nicotinium chloride, a N-donor quaternary ammonium salt

Abstract

A novel and effective catalytic system using monobenzylnicotinium chloride combined with copper(I) chloride was employed for the first time in Sonogashira cross-coupling reactions of phenylacetylene with various aryl halides. The goal was to use an efficient green media by using copper instead of palladium in metal-catalyzed coupling reactions. Monobenzyl nicotinium chloride, a quaternary ammonium salt containing a coordinating centre, plays an important role in this catalytic system and increases the efficiency of Cu(I) species during the reaction. A number of internal alkynes were produced in moderate to excellent yields in short reaction times in DMF at 135–140 °C. The efficiency of this catalytic system was compared with the copper-based catalyst obtained from dibenzylnicotinium chloride which has no N-donor active site, wherein lower activity was observed due to lack of a coordination site.