Iron‐Catalysed C(sp2)‐H Borylation with Expanded Functional Group Tolerance†

Abstract

Comprehensive SummaryArene C(sp2)‐H bond borylation offers direct and efficient access to aryl boronic esters. Using in situ catalyst activation and photoirradiation, the iron‐catalysed C(sp2)‐H borylation reaction of carboarenes, pyrroles, and indoles has been developed using only bench‐stable pre‐catalysts and reagents. Good functional group tolerance was observed including those not reported using previous methods (ArNH2, ArOH, ArSiR3, ArP(O)(OR)2, ArC(O)NR2). Mechanistic studies revealed iron‐catalysed reductive deoxygenation, C—F protodefluorination, and a demethylation of aryl methyl ethers by C—O sigma bond hydroboration.