Orthometalation of Primary Amines. 4.<sup>1</sup> Orthopalladation of Primary Benzylamines and (2-Phenylethyl)amine
作者:José Vicente、Isabel Saura-Llamas、Michael G. Palin、Peter G. Jones、M. Carmen Ramírez de Arellano
DOI:10.1021/om9609574
日期:1997.3.1
By the refluxing of an acetonitrile solution of [Pd(OAc)(2)](3) and primary amines 4-XC(6)H(4)CH(2)NH(2) (F, Cl, NO2, OMe), 3,5-X(2)C(6)H(3)CH(2)NH(2) (X = OMe), or PhCH(2)CH(2)NH(2) (Pd:amine = 1:1) and subsequent addition of excess NaBr, the corresponding orthometalated complexes [PdC6H3(CH2NH2)-2,X-5}(mu-Br)](2), [PdC6H3(CH2NH2)-2,(OMe)(2)-4,6}(mu-Br)](2), or [PdC6H3(CH2NH2)-2}(mu-Br)](2) are obtained. Alternatively, the hydrochloride of 4-XC(6)H(4)CH(2)NH(2) (X = F, NO2) can also be used to prepare the corresponding [PdC6H3(CH2NH2)-2,X-5}(mu-Cl)](2) complexes. These results show that primary benzylamines can be orthometalated even if the substituents are electron-withdrawing groups and that 2-(phenyl)ethylamine can be orthometalated in spite of the six-membered ring that it forms. These reactions occur via intermediate complexes [Pd(OAc)(2)L(2)], which react with [Pd(OAc)(2)](3) to give the dimeric species [Pd(OAc)(mu-OAc)L](2) (L = amine), from which in turn the orthometalated complexes are formed. Each of these steps has been studied, and both types of intermediates have been isolated for all the amines. PPh(3) reacts with the orthometalated complexes to give the corresponding products of the bridge splitting. The crystal structures of [Pd(OAc)(mu-OAc)L](2) (L = 4-O2NC6H4CH2NH2) and [PdC6H4(CH2CH2NH2)-2}Br(PPh(3))] have been determined by X-ray diffraction.