97360-41-3Relevant academic research and scientific papers
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.
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.
Selenium catalyzed conversion of δ-phenyl- γ-alkenyl oximes into 2-phenylpyridines
Tiecco, Marcello,Testaferri, Lorenzo,Bagnoli, Luana,Marini, Francesca,Santi, Claudio,Temperini, Andrea
, p. 2679 - 2686 (2007/10/03)
δ-Phenyl-γ-alkenyl oximes react with an excess of ammonium persulfate and catalytic amounts of diphenyl diselenide in the presence of trifluoromethanesulfonic acid in acetonitrile to afford 2-phenylpyridines and 2-phenylpyridine N-oxides in moderate yields.
