Palladium complexes with hydrophosphorane ligands (HP∼O and HP∼N), catalysts for Heck cross-coupling reactions

The synthesis and structural characterization of palladium complexes 1-3 incorporating H-spirophosphorane HP(OCMe2CMe2O)(2) and H-phosphonate congener HP(O)(OCMe2CMe2O) ligands are reported. The chemical composition of the complexes [PdCl(mu-Cl){P(OCMe2CMe2O)OCMe2CMe2OH}](2) (1), [Pd{P(O)(OCMe2CMe2O)}(2)](n) (2), and [Pd(mu-Cl){P(OCMe2CMe2O)OH}{P(OCMe2CMe2O)O}](2) (3) was established by means of NMR, IR, ESI-MS spectroscopic methods. The relative stereochemistry of 1 and 3 was unambiguously determined by single X-ray diffraction studies. It was proved that complexes 1-3, and complex [PdCl2P(OCH2CMe2NH)OCH2CMe2NH2] (4) previously described in the literature, are very efficient catalysts for the Heck cross-coupling of bromobenzene with n-butyl acrylate. Moreover, they were also found to be effective catalysts in the stereoselective synthesis of trans-stilbenes. (C) 2010 Elsevier B. V. All rights reserved.