Green Approach for Copper‐Free Pd‐catalyzed Sonogashira Cross‐Coupling using Saponin‐Based Micellar Catalysis in Water at Ambient Temperature

Abstract

A micellar catalysis that is derived from commercially available saponin for copper‐free, Pd‐catalyzed Sonogashira cross‐coupling under mild reaction conditions has been developed. Using this green and sustainable method, a broad range of aryl/heteroaryl and alkyl terminal alkynes were cross‐coupled with aryl/heteroaryl halides at ambient temperature in an aqueous medium. The commercially available, inexpensive, and plant‐based natural saponin served as a surfactant for a micellar system that effectively enabled C(sp2)‐C(sp) cross‐coupling with a wide range of substrates. The attractive features of this protocol are the use of water as a reaction medium, the in‐situ generation of the micellar‐catalysis system from biodegradable natural saponins, good functional group tolerance, scalability of the products, and notably the ability to retain the catalyst activity by recycling the aqueous reaction medium.