Rh-Catalyzed Ortho-Selective C–H Borylation of N-Functionalized Arenes with Silica-Supported Bridgehead Monophosphine Ligands
journal contributionposted on 07.12.2011, 00:00 by Soichiro Kawamorita, Tatsuya Miyazaki, Hirohisa Ohmiya, Tomohiro Iwai, Masaya Sawamura
Supported phosphine-Rh systems, prepared in situ from silica-supported bridgehead monophosphines and [Rh(OH)(cod)]2, have enabled ortho-selective C–H borylation for a range of arenes containing nitrogen-based directing groups. The regioselectivity was excellent with various N-directing groups, including saturated and unsaturated N-heterocycles, tert-aminoalkyl groups, and imine-type C–N double bonds. The reaction showed significant tolerance toward steric repulsion around the reacting C–H bond. This Rh catalysis complements the Ir-catalyzed ortho-borylation, which is effective for arenes with oxygen-based directing groups.