화학공학소재연구정보센터
Journal of Molecular Catalysis A-Chemical, Vol.391, 183-190, 2014
P-Stereogenic monophosphines with the 2-p-terphenylyl and 1-pyrenyl substituents. Application to Pd and Ru asymmetric catalysis
The synthesis of five optically pure P-stereogenic monophosphines of the type PPhArR (Ar = 2-p-terphenylyl (a), 1-pyrenyl (b); R = OMe, Me, i-Pr) is described. The ligands were fully characterised and the absolute configurations of PPh(1-pyrenyl)R (3b and 5b; R = OMe and Me respectively) were confirmed by X-ray diffraction. The complexation of the monophosphines to Pd and Ru organometallic units yielded the neutral complexes [PdCl(eta(3)-2-Me-allyl)P] (10-12) and [RuCl2(eta(6)-p-cymene)P] (16-18). Complete characterisation, including the crystal structure determination of [RuCl2(eta(6)-p-cymene)(PMePh(2-p-terphenyl))] (17a) is provided. Neutral palladium complexes appeared as mixtures of two diastereomers in solution according to NMR. The synthesis and characterisation of four cationic [Pd(eta(3)-2-Me-allyl)(P)(2)]PF6 (13 and 14) is also described. The application of neutral Pd complexes to catalytic styrene hydrovinylation afforded moderate conversions, high chemoselectivities (>92%) to 3-phenyl-1-butene and up to 43% ee with precursor 12a. Cationic Pd complexes were tested as catalytic precursors in allylic substitution of rac-3-acetoxy-1,3-diphenyl-1-propene (rac-I), with the anion of dimethylmalonate and benzylamine as nucleophiles, obtaining full conversions and up to 80% ee in alkylation and 60% ee in amination with precursor 13a. Finally, ruthenium complexes were used as catalytic precursors in transfer hydrogenation of acetophenone, with complete conversions after several hours but low enantioselectivities. (C) 2014 Elsevier B.V. All rights reserved.