The preparation of the new ligand 8-(di-tert-butylphosphinooxy)quinoline (1) and the palladium derivatives (PdCl2(1)) (2), (Pd(n3-all)(1))+ (all = C3H5 (3a), 1-PhC3H4 (3b) and 1,3-Ph2C3H3 (3c)] and (Pd(n2-(ol)(1)) (ol = dimethyl fumarate (4a) and fumaronitrile (4b)) is reported. The cationic species 3a3c have been isolated as BF4- salts. The complex 3a(BF4) is obtained either from the reaction of 1 with (Pd(u-Cl)(n3-C3H5))2 or from the reaction of ClP(CMe3)2 with (Pd(n3-C3H5)(8-oxyquinoline)), followed in both cases by chloride abstraction with NaBF4. In the complexes, the ligand 1 is P,N chelated to the central metal, as shown by the X-ray structural analysis of 3a(BF4). At 25°C in solution, 3a(BF4) and 3b(BF4) undergo a fast n3-n1-n3 dynamic process which brings about a synanti exchange only for the allylic protons cis to phosphorus, while for 4a and 4b a slow rotation of the olefin around its bond axis to palladium takes place. The complexes 2 and 3a(BF4) are efficient catalyst precursors in the coupling of the phenylboronic acid with aryl bromides and chlorides.
Palladium complexes of 8-(di-tert-butylphosphinooxy) quinoline
2008
Abstract
The preparation of the new ligand 8-(di-tert-butylphosphinooxy)quinoline (1) and the palladium derivatives (PdCl2(1)) (2), (Pd(n3-all)(1))+ (all = C3H5 (3a), 1-PhC3H4 (3b) and 1,3-Ph2C3H3 (3c)] and (Pd(n2-(ol)(1)) (ol = dimethyl fumarate (4a) and fumaronitrile (4b)) is reported. The cationic species 3a3c have been isolated as BF4- salts. The complex 3a(BF4) is obtained either from the reaction of 1 with (Pd(u-Cl)(n3-C3H5))2 or from the reaction of ClP(CMe3)2 with (Pd(n3-C3H5)(8-oxyquinoline)), followed in both cases by chloride abstraction with NaBF4. In the complexes, the ligand 1 is P,N chelated to the central metal, as shown by the X-ray structural analysis of 3a(BF4). At 25°C in solution, 3a(BF4) and 3b(BF4) undergo a fast n3-n1-n3 dynamic process which brings about a synanti exchange only for the allylic protons cis to phosphorus, while for 4a and 4b a slow rotation of the olefin around its bond axis to palladium takes place. The complexes 2 and 3a(BF4) are efficient catalyst precursors in the coupling of the phenylboronic acid with aryl bromides and chlorides.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
