Multidonor Ligands. 3. Cyclopalladation of py{SCH<sub>2</sub>C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp<sup>3</sup>)−H Bond Activation
作者:José Vicente、María-Teresa Chicote、Concepción Rubio、M. Carmen Ramírez de Arellano、Peter G. Jones
DOI:10.1021/om981043f
日期:1999.7.1
[PdCl2(NCPh)(2)] reacts with R-carbonylmethylenethiopyridines [pySCH2C(O)R}-2] to give, depending on the substituent R and the reaction conditions, [PdpySCHC(O)Ph}-2}(mu-Cl)(2)Pd-pySCH2C(O)Ph}-2}Cl] or the coordination complexes [PdpySCH2C(O)R}-2}(2)Cl-2] (R = Ph, Me, OMe). The latter can be doubly deprotonated by a base (Na2CO3 or NaH) to give dicyclometalated complexes cis-[PdpySCHC(O)R}-2}(2)]. These transmetalate one ligand to [PdCl2(NCPh)(2)] to give [Pdpy(SCHC(O)R}-2}(mu-Cl)](2), which in turn reacts with (Me4N)Cl or with monodentate ligands L or with MeCN in the presence of AgClO4 to give anionic Me4N[PdpySCHC(O)Ph}-2}Cl-2], neutral [Pdpy(SCHC(O)R}-2}Cl(L)] [R = Ph, L = PPh3, pySCH2C(O)Ph}-2, (BuNC)-Bu-t, NH2CH(Me)Ph, pyridine (py), tetrahydrothiophene (tht); R= Me, L = PPh3, py, tht], or cationic [PdpySCHC(O)R}-2}(NCMe)(2)]ClO4 (R = Ph, Me, OMe) complexes, respectively. The latter react with PPh3 or with bidentate ligands to give complexes [PdpySCHC(O)Ph}-2}(NCMe)(PPh3)]ClO4 or [Pd(pySCHC(O)Ph}-2}L-2]ClO4 [L = PPh3, L-2 = N,N,N',N'-tetramethylethylenediamine (tmeda) or 2,2'-bipyridine (bipy)]. The crystal structures of [PdpySCHC(O)R}-2}(2)] and [PdpySCHC(O)R}-2}ClpySCH2C(O)R}2}] have been determined.