Recent advances in manganese-catalysed C–H activation: scope and mechanism

As a synthetic methodology, C–H activation represents a complimentary protocol to traditional cross-couplings such as the Suzuki–Miyaura and Stille reactions, by avoiding the extra synthetic steps required to install activating groups. C–H activation also often avoids the production of waste associated with B, Sn, halide etc. Pd-catalysed transformations have been most prominent in the C–H activation realm. However, as a society we are over-reliant on transitional metals, cost is increasing, and the accessible supply is dwindling. One potential solution is to develop chemistry using Earth Abundant Metals (EAMs). Manganese (Mn), in particular, demonstrates great promise. Since the publication of an excellent review by Ackermann in 2016 (ACS Catal. 2016, 6, 3743–3652), there has been a flurry of reports on Mn-catalysed C–H activation. We report here an overview of approximately 30 new papers, which include a number of notable advances since April 2016