HFIP‐assisted C‐H functionalization by Cp*Co(III): Promoted Access to Key Reactive Cobaltacycles and Implication in Catalysis

Herein, we describe our synthetic approach to access two of the most widely invoked cationic cobaltacycles in Cp*Co(III)‐catalyzed C‐H functionalization reactions via C‐H activation. We take advantage of the unique stabilizing capability of MeCN to surmount the previously proposed reversible nature of the C‐H metalation step. Moreover, we also uncover the boosting effect of HFIP in the metalation step and in the reactivity, under catalytic conditions, between N‐pyrimidinylindole and diphenylacetylene.