Electromagnetic milling-promoted steel rod-enabled Sonogashira coupling reactions of aryl halides and terminal alkynes

Abstract

Nickel-catalyzed Sonogashira reactions between aryl halides and terminal alkynes have become a powerful method for constructing C(sp²)–C(sp) bonds. Conventional approaches typically required copper co-catalysts, solvents, inert atmospheres, and external heating. Herein, we report an alternative and streamlined reductive C(sp²)–C(sp) cross-coupling protocol that employs an inexpensive nickel catalyst, eliminating the need for Ni/Cu dual catalysts. This electromagnetic milling (EMM) promoted strategy effectively circumvents the constraints associated with traditional nickel-catalyzed Sonogashira reactions. Mechanistic studies reveal that the Ni(II) precursor in NiCl₂ is activated under a magnetic field and in the presence of DABCO to produce Ni(0) as the active catalyst, and EMM plays a critical role in promoting reductive elimination from the Ni^II complex.