247185-52-0Relevant articles and documents
Kinetic resolution of pyridyl alcohols by Cu(II)(borabox)-catalyzed acylation
Roseblade, Stephen J.,Pfaltz, Andreas
, p. 3751 - 3753 (2007)
Kinetic resolution of pyridyl alcohols has been achieved using copper(II)(borabox)-catalyzed benzoylation. Selectivity factors (k rel) of up to 125 have been observed and application to the synthesis of chiral pyridyl phosphine ligands is descr
Method for preparing chiral nitrogen-phosphorus ligand L-8 containing pyridocyclopentane
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Paragraph 0066-0071, (2021/03/23)
The invention discloses a method for preparing chiral nitrogen-phosphorus ligand L-8 containing pyridocyclopentane, and belongs to the technical field of medical intermediate chiral ligands. The chiral nitrogen-phosphorus L-8 ligand is prepared from cyclopentanone through the steps of addition, cyclization, chlorination, asymmetric boronation, oxidation, coupling, esterification and the like in sequence, large-scale preparation is relatively easy to achieve through the route, and the defect that in a traditional route, the yield is low in the first step of ring closing reaction and chiral alcohol preparation is overcome, and by selecting a proper chiral ligand, and combining with butyl lithium, asymmetric synthesis of chiral alcohol is realized, and a chiral separation column mode adoptedin literature is avoided.
Method for synthesizing chiral nitrogen-phosphorus ligand L-8 containing pyridocycloheptane
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Paragraph 0066-0072, (2021/03/23)
The invention discloses a method for synthesizing a chiral nitrogen-phosphorus ligand L-8 containing pyridocycloheptane, and belongs to the technical field of medical intermediate chiral ligands. Thechiral nitrogen-phosphorus L-8 ligand is prepared from cyclopentanone through the steps of addition, cyclization, chlorination, asymmetric boronation, oxidation, coupling, esterification and the likein sequence, large-scale preparation is relatively easy to achieve through the route, and the defect that in a traditional route, the yield is low in the first step of ring closing reaction and chiralalcohol preparation, and by selecting a proper chiral ligand, and combining with butyl lithium, asymmetric synthesis of chiral alcohol is realized, and a chiral separation column mode adopted in literature is avoided.
Optimized Scalable Synthesis of Chiral Iridium Pyridyl-Phosphinite (Pyridophos) Catalysts
Müller, Marc-André,Gani?, Adnan,H?rmann, Esther,Kaiser, Stefan,Maywald, Matthias,Roseblade, Stephen J.,Schrems, Marcus G.,Schumacher, Andreas,Woodmansee, David,Pfaltz, Andreas
, (2020/12/01)
Iridium catalysts with chiral P,N ligands have greatly enhanced the scope of asymmetric olefin hydrogenation because they do not require a coordinating group near the C=C bond like Rh and Ru catalysts. Pyridophos ligands, possessing a conformationally restricted annulated pyridine framework linked to a phosphinite group, proved to be particularly effective, inducing high enantioselectivities in the hydrogenation of a remarkably broad range of substrates. Here we report the development of an efficient scalable synthesis for the two most versatile Ir-pyridophos catalysts, derived from 2-phenyl-8-hydroxy-5,6,7,8-tetrahydroquinoline or the analogue with a five-membered carbocyclic ring, respectively, by modification and optimization of the original synthetic route. The optimized route renders both catalysts readily accessible in multi-gram quantities in analytically pure form in overall yields of 26–37 %, starting from acetophenone and cyclopentanone or cyclohexanone, respectively. A major advantage of the new synthesis is the efficient and practical kinetic resolution of the late-stage pyridyl alcohol intermediates with commercial immobilized Candida antarctica lipase B, giving access to both enantiomers of these catalysts as essentially enantiopure compounds. The catalysts are obtained as crystalline solids, which are air-stable and can be stored for years at ?20 °C without notable decomposition.
Application of Crabtree/Pfaltz-Type Iridium Complexes for the Catalyzed Asymmetric Hydrogenation of an Agrochemical Building Block
Schneek?nig, Jacob,Liu, Weiping,Leischner, Thomas,Junge, Kathrin,Schotes, Christoph,Beier, Christian,Beller, Matthias
supporting information, p. 443 - 447 (2020/04/08)
Herein we report improved chemo- A nd enantioselective hydrogenations of 1-(2,2,4-trimethylquinolin-1(2H)-yl)ethan-1-one (1) toward (R)-1-(2,2,4-trimethyl-3,4-dihydroquinolin-1(2H)-yl)ethan-1-one (2) using well-defined novel Crabtree-type iridium complexe
Iron(ii)-bis(isonitrile) complexes: Novel catalysts in asymmetric transfer hydrogenations of aromatic and heteroaromatic ketones
Naik, Anu,Maji, Tapan,Reiser, Oliver
supporting information; experimental part, p. 4475 - 4477 (2010/11/03)
Chiral iron(ii)-bis(isonitrile) complexes catalyse the transfer hydrogenation of aromatic ketones with enantioselectivities up to 91% ee, most likely via hydride transfer through imine intermediates, generated by in situ reduction of the isonitrile ligands, whereas iron acts as a Lewis acid to activate the ketone.
Chromatography-free enzymatic kinetic resolution of secondary alcohols
Maywald, Matthias,Pfaltz, Andreas
experimental part, p. 3654 - 3660 (2010/03/25)
Racemic secondary alcohols were resolved by enzymatic esterification using Candida antarctica lipase B (CAL B). After derivatization of the unreacted enantiomer with phthalic anhydride, the resulting phthalic acid monoesters could be easily separated from the corresponding acetates by precipitation and filtration or distillation, thus avoiding laborious column chromatography, which is a major obstacle for large-scale reactions. This method has been successfully applied to the multigram synthesis of enantiopure pyridyl alcohols.
Design and synthesis of new chiral pyridine-phosphite ligands for the copper-catalyzed enantioselective conjugate addition of diethylzinc to acyclic enones
Xie, Yinjun,Huang, Hanmin,Mo, Weimin,Fan, Xiangqun,Shen, Zhiqiang,Shen, Zhenlu,Sun, Nan,Hu, Baoxiang,Hu, Xinquan
experimental part, p. 1425 - 1432 (2009/12/04)
A series of new chiral pyridine-phosphite ligands have been prepared from (R)-pyridyl alcohols and BINOL-derived chlorophosphite, and successfully employed in the copper-catalyzed enantioselective conjugate addition of diethylzinc to acyclic enones. Using the simple and inexpensive CuBr2 as a precursor, the enantioselective additions to various substituted acyclic enones afforded products in high yields and good enantioselectivities (up to 92% ee).
Iridium catalysts with bicyclic pyridine-phosphinite ligands: Asymmetric hydrogenation of olefins and furan derivatives
Kaiser, Stefan,Smidt, Sebastian P.,Pfaltz, Andreas
, p. 5194 - 5197 (2007/10/03)
(Chemical Equation Presented) Superior bicyclics: Iridium catalysts as 1 derived from pyridine-phosphinite ligands considerably extend the scope of asymmetric hydrogenation. In addition to various unfunctionalized and functionalized olefins, furans, and benzofurans, for which no catalysts were known before, are also hydrogenated with high enantioselectivity (see scheme).
Kinetic resolution of diols and pyridyl alcohols by cu(II)(borabox)- catalyzed acylation
Mazet, Clement,Roseblade, Stephen,Koehler, Valentin,Pfaltz, Andreas
, p. 1879 - 1882 (2007/10/03)
Boron-bridged bisoxazoline (borabox) ligands have been used in the copper(II)-catalyzed benzoylation of pyridyl alcohols and 1,2-diols. Efficient kinetic resolution of 1,2-diols was achieved using both borabox and bisoxazoline (box) ligands. Borabox ligands induced high selectivities in the benzoylation of suitable pyridyl alcohols, where they outperformed bisoxazolines. In addition, highly enantioselective Cu(II)(borabox)-catalyzed benzoylation has been used for the synthesis of both enantiomers of a pyridyl alcohol.
