Preparation, structures, and thermal reactivity of alkoxycarbonyl(cyano) palladium(II) complexes trans-Pd(COOR)(CN)(PPh3)2 (R = Me, Et, nPr, iPr, nBu, tBu, and Bn) as intermediates of the palladium-catalyzed cyanoesterification of norbornene derivatives

Yasushi Nishihara, Mitsuru Miyasaka, Yoshiaki Inoue, Tomoka Yamaguchi, Masaaki Kojima, Kentaro Takagi

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31 Citations (Scopus)

Abstract

Alkoxycarbonyl(cyano)palladium(II) complexes trans-Pd(COOR)(CN)(PPh 3)2 (1, R = Me; 2, R = Et; 3,R = nPr; 4, R = iPr; 5, R = nBu; 6, R = tBu; 7, R = Bn) are prepared via oxidative addition of the corresponding cyanoformates to Pd(PPh 3)4 in toluene at room temperature or 50 °C and characterized by means of NMR (1H, 13C{1H}), and 31P{1H}) and IR spectroscopy as well as elemental analyses. X-ray crystallography of 3, 4, and 6 showed a square-planar coordination around the Pd center that is bonded to alkoxycarbonyl and cyano ligands in the trans configuration. The Pd-CN and Pd-COOR bonds in 1, 3, 4, and 6 are similar to those of the cyanopalladium(II) and alkoxycarbonylpalladium(II) complexes reported to date. On reaction of Pd(PPh3)4 with phenyl cyanoformate a thermally induced ligand exchange takes place to afford the dicyanopalladium(II) complex, trans-Pd(CN)2(PPh3)2 (8). Complex 2 is able to catalyze the reaction of norbornadiene with ethyl cyanoformate to produce (2R*,3S*)-ethyl 3-cyanobicyclo[2.2.1]hept-5- ene-2-carboxylate (13) and is recovered after the reaction. This observation supports the identification of alkoxycarbonyl(cyano)palladium(II) complexes as intermediates in the catalytic cycle of cyanoesterification of norbornene derivatives.

Original languageEnglish
Pages (from-to)4054-4060
Number of pages7
JournalOrganometallics
Volume26
Issue number16
DOIs
Publication statusPublished - Jul 30 2007

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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