HFIP‐Assisted C−H Functionalization by Cp*CoIII: Access to Key Reactive Cobaltacycles and Implication in Catalysis

Described here is a synthetic approach to access two of the most widely invoked cationic cobaltacycles in Cp*CoIII‐catalyzed C−H functionalization reactions by C−H activation. The unique stabilizing capability of MeCN was used to surmount the previously proposed reversible nature of the C−H metalation step. Moreover, it is revealed the boosting effect of 1,1,1,3,3,3‐hexafluoroisopropanol in the metalation step and in the reaction between N‐pyrimidinylindole and diphenylacetylene under catalytic conditions.