TY - JOUR
T1 - 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
AU - Nishihara, Yasushi
AU - Miyasaka, Mitsuru
AU - Inoue, Yoshiaki
AU - Yamaguchi, Tomoka
AU - Kojima, Masaaki
AU - Takagi, Kentaro
PY - 2007/7/30
Y1 - 2007/7/30
N2 - 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.
AB - 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.
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U2 - 10.1021/om700343y
DO - 10.1021/om700343y
M3 - Article
AN - SCOPUS:34547820862
SN - 0276-7333
VL - 26
SP - 4054
EP - 4060
JO - Organometallics
JF - Organometallics
IS - 16
ER -