Flow Rhodaelectro-Catalyzed Alkyne Annulations by Versatile C−H Activation: Mechanistic Support for Rhodium(III/IV)

A flow-metallaelectro-catalyzed C−H activation was realized in terms of robust rhodaelectro-catalyzed alkyne annulations. To this end, a modular electro-flow-cell with a porous graphite felt anode was designed to ensure efficient turnover. Thereby, a variety of C−H/N−H functionalizations proved amenable for alkyne annulations with high levels of regioselectivity and functional group tolerance, viable both in an inter- or intramolecular manner. The electro-flow C−H activation allowed easy scale up, while in-operando kinetic analysis was accomplished by on-line flow-NMR spectroscopy. Mechanistic studies sug-gest an oxidatively-induced reductive elimination pathway on rhodium(III) in an electrocatalytic regime.