Ortho-Metalated Primary Amines. 6.1 The First Synthesis of Six-Membered Palladacycles from Primary Amines Containing Electron-Withdrawing Substituents: End of the Limiting Rules of Cope and Friedrich on Cyclopalladation of Benzyl- and Phenethylamines
When H 2 N(CH 2 ) 2 C 6 H 4 OMe-4 (RNH 2 ) and Pd(OAc) 2 are reacted in a 2:1 molar ratio, the complex [Pd(OAC) 2 (NH 2 R) 2 ] (1) is obtained. Complex 1 reacts with 1 equiv of Pd(OAc) 2 to give the dinuclear complex [Pd(OAc)(μ-OAc)(NH 2 R)] 2 (2). When complex 2 is heated in acetonitrile at 80 °C, the ortho-metalated complex [Pd{C 6 H 3 (CH 2 ) 2 NH 2 -2-OMe-5-κ 2 C,N}(μ-OAc)] 2 (3a) is obtained. Complex 3a is also prepared by refluxing RNH 2 and Pd(OAc) 2 in a 1:1 molar ratio in acetonitrile. Complex 3a reacts with NaBr or LiCl to afford the complexes [Pd{C 6 H 3 (CH 2 ) 2 NH 2 -2-OMe-5-κ 2 C,N}(μ-X)]2 (X = Cl (3b), Br (3c)). PPh 3 splits the acetate or halide bridge in complex 3a or 3b t…
Insertion of One, Two, and Three Molecules of Alkyne into the Pd−C Bond of Ortho-palladated Primary and Secondary Arylalkylamines
The ortho-metalated complex [Pd2{κ2(C,N)-C6H4CH2CH2NHMe-2}2(μ-Br)2] (1) can be prepared by refluxing a 1:1 mixture of Pd(OAc)2 and N-methylphenethylamine in acetonitrile, followed by addition of an excess of NaBr. Complex 1 reacts with PPh3 to give the mononuclear derivative [Pd{κ2(C,N)-C6H4CH2CH2NHMe-2}Br(PPh3)] (2). The cationic complex [Pd{κ2(C,N)-C6H4CH2CH2NHMe-2}(py)2]ClO4 (3) can be obtained by reacting 1 with AgClO4 and pyridine. The previously reported complex [Pd2{κ2(C,N)-C6H4CH2NHCH2Ph-2}2(μ-Br)2] (A) reacts with PhC≡CCO2R (R = Me, Et) to give the monoinserted derivatives [Pd2{κ2(C,N)-C(Ph)═C(CO2R)C6H4CH2NHCH2Ph-2}2(μ-Br)2] (R = Me (4a), Et (4b)). These dimers react with neutral l…