Divergent C–H Alkylation and Allylation of Indoles with Unactivated Alkene via Mechanochemical Rh(III) Catalysis

A tunable mechanochemical platform is reported for Rh(III)-catalyzed C2-alkylation (via electrophilic C-H activation) or C2-allylation (via CMD) of indoles with unactivated alkenes, controlled simply by fine-tuning the reagent composition. 1,1-Disubstituted alkenes undergo Rh-free Ag-catalyzed C3-branched alkylation, enabling one-pot synthesis of <i>N</i>-free indoles via tandem coupling-deprotection. The protocol offers broad substrate scope, high yields and selectivity, scalability, and applicability to late-stage drug modification, providing a sustainable and efficient route to valuable indole derivatives.