Iron-Catalyzed\nMiyaura Borylation of Aryl Chlorides\nand Triflates

Simple aryl chlorides represent challenging substrates\nin iron-catalyzed\nborylation. A combination of Li[B(<sup>t</sup>Bu)pin-Bpin] as the\nborylating reagent and a catalyst formed in situ from iron(II) triflate\nand the commercially available N-heterocyclic carbene ligand, IMes,\ngives significantly improved activity and a much broader scope than\npreviously reported iron-based catalysts. Iron triflate is also a\ngood precatalyst for the borylation of aryl triflatesa previously\nunreported transformationand in these cases the IMes ligand\nis not required.