Mechanochemical C−H Arylation and Alkylation of Indoles Using 3 d Transition Metal and Zero‐Valent Magnesium

Abstract Although the 3 d transition‐metal catalyzed C−H functionalization have been extensively employed to promote the formation of valuable carbon‐carbon bonds, the persistent problems, including the use of sensitive Grignard reagents and the rigorous operations (solvent‐drying, inert gas protection, metal pre‐activation and RMgX addition rate control), still leave great room for further development of sustainable methodologies. Herein, we report a mechanochemical technology toward in‐situ preparation of highly sensitive organomagnesium reagents, and thus building two general 3 d transition‐metal catalytic platforms that enables regioselective arylation and alkylation of indoles with a wide variety of halides (including those containing post transformable functionalities and heteroaromatic rings). This mechanochemical strategy also brings unique reactivity and high step‐economy in producing functionalized N ‐free indole products.