73854-04-3Relevant articles and documents
Tridentate nitrogen phosphine ligand containing arylamine NH as well as preparation method and application thereof
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Paragraph 0095-0102; 0105-0109, (2021/06/26)
The invention discloses a tridentate nitrogen phosphine ligand containing arylamine NH as well as a preparation method and application thereof, and belongs to the technical field of organic synthesis. The tridentate nitrogen phosphine ligand disclosed by the invention is the first case of tridentate nitrogen phosphine ligand containing not only a quinoline amine structure but also chiral ferrocene at present, a noble metal complex of the type of ligand shows good selectivity and extremely high catalytic activity in an asymmetric hydrogenation reaction, meanwhile, a cheap metal complex of the ligand can also show good selectivity and catalytic activity in the asymmetric hydrogenation reaction, and is very easy to modify in the aspects of electronic effect and space structure, so that the ligand has huge potential application value. A catalyst formed by the ligand and a transition metal complex can be used for catalyzing various reactions, can be used for synthesizing various drugs, and has important industrial application value.
Towards practical earth abundant reduction catalysis: Design of improved catalysts for manganese catalysed hydrogenation
Widegren, Magnus B.,Clarke, Matthew L.
, p. 6047 - 6058 (2019/11/14)
Manganese catalysts derived from tridentate P,N,N ligands can be activated easily using weak bases for both ketone and ester hydrogenations. Kinetic studies indicate the ketone hydrogenations are 0th order in acetophenone, positive order in hydrogen and 1st order in the catalyst. This implies that the rate determining step of the reaction was the activation of hydrogen. New ligand systems with varying donor strength were studied and it was possible to make the hydrogen activation significantly more efficient; a catalyst displaying around a 3-fold increase in initial turn-over frequencies for the hydrogenation of acetophenone relative to the parent system was discovered as a result of these kinetic investigations. Ester hydrogenations and ketone transfer hydrogenation (isopropanol as reductant) are first order for both the substrate and catalysts. Kinetic studies also gained insight into catalyst stability and identified a working range in which the catalyst is stable throughout the catalytic reaction (and a larger working range where high yields can still be achieved). The new more active catalyst, combining an electron-rich phosphine with an electron-rich pyridine is capable of hydrogenating acetophenone using as little as 0.01 mol% catalyst at 65 °C. In all, protocols for reduction of 21 ketones and 15 esters are described.
Osmium(II)/R-pybox vs ruthenium(II)/R-pybox complexes in the catalytic asymmetric transfer hydrogenation of arylketones
de Julián, Eire,Fernández, Nuria,Díez, Josefina,Lastra, Elena,Gamasa, M. Pilar
, p. 75 - 86 (2018/07/25)
The reaction of the complexes trans-[RuCl2(η2-C2H4){(S,S)-iPr-pybox}] (1a) and trans-[RuCl2(η2-C2H4){(R,R)-Ph-pybox}] (1b) with nitrogen heterocyclic ligands, provide the complexes trans-[RuCl2(L)(R-pybox)] (L = py (3a,b), 3-Br-py (4a,b), isoquinoline (5a,b), pyrazine (6a,b), 1-methylimidazole (7a,b), 1-benzylimidazole (8a,b), pyrazole (9a,b), 3-methylpyrazole (10a,b), and 1H-1,2,4-triazole (11a,b)). The complexes trans-[OsCl2(L){(S,S)-iPr-pybox}] (L = py (12), 3-Br-py (13), 3-CN-py (14), 3-MeO-py (15), 3-NO2-py (16), 4-CN-py (17), 4-MeO-py (18), isoquinoline (19), 1-methylimidazole (20), 1-benzylimidazole (21), pyrazole (22)) have been similarly synthesized by the substitution of ethylene from the precursor complex trans-[OsCl2(η2-C2H4){(S,S)-iPr-pybox}] (2) by the corresponding N-donor ligand in refluxing toluene. Moreover, the dinuclear complexes [(RuCl2{(S,S)-iPr-pybox})2(μ-N,N-C4H4N2)] (23a), [(RuCl2{(R,R)-Ph-pybox})2(μ-N,N-C4H4N2)] (23b) and [(OsCl2{(S,S)-iPr-pybox})2(μ-N,N-C4H4N2)] (24) have been prepared by the reaction of the complexes 1 and 2 with pyrazine (1:0.5 M ratio for 23 and 1:1.5 for 24). The structure of the complexes 9a, 12, 23a and 24 has been determined by single-crystal X-ray diffraction analysis. The ruthenium 3a,b, 6a and 10a,b and osmium complexes 12–22 and 24 have been assayed as catalysts for the asymmetric transfer hydrogenation reaction. Among them, the osmium complexes 12, 15, 16, 18 and 24 have proven more efficient in the reduction of a variety of aromatic ketones affording the (R)-benzylalcohols with very high conversion and moderate enantioselectivity up to 73% e.e.
