Mechanistic insights into the transmetalation step of a Suzuki-Miyaura reaction of 2(4)-bromopyridines: characterization of an intermediate

The mechanistic study of the palladium-catalyzed Suzuki-Miyaura cross-coupling between bromophenylpyridine compounds and phenylboronic acid led to the NMR identification of a transient intermediate in the transmetalation step. This species was identified by DFT calculations as a [Pd{Ph-B(OH)(3)(-)}-{C5H2RN}(PR3)(2)] complex, containing a boronate ligand coordinated through an oxygen group to the metal center. The fitting of this intermediate within recent mechanistic proposals on the mechanism of transmetalation is discussed. (c) 2008 Elsevier Ltd. All rights reserved.