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.