1780-19-4Relevant articles and documents
Iridium-catalyzed hydrogenation of N-heterocyclic compounds under mild conditions by an outer-sphere pathway
Dobereiner, Graham E.,Nova, Ainara,Schley, Nathan D.,Hazari, Nilay,Miller, Scott J.,Eisenstein, Odile,Crabtree, Robert H.
, p. 7547 - 7562 (2011)
A new homogeneous iridium catalyst gives hydrogenation of quinolines under unprecedentedly mild conditions-as low as 1 atm of H2 and 25 °C. We report air-and moisture-stable iridium(I) NHC catalyst precursors that are active for reduction of a wide variety of quinolines having functionalities at the 2-, 6-, and 8-positions. A combined experimental and theoretical study has elucidated the mechanism of this reaction. DFT studies on a model Ir complex show that a conventional inner-sphere mechanism is disfavored relative to an unusual stepwise outer-sphere mechanism involving sequential proton and hydride transfer. All intermediates in this proposed mechanism have been isolated or spectroscopically characterized, including two new iridium(III) hydrides and a notable cationic iridium(III) dihydrogen dihydride complex. DFT calculations on full systems establish the coordination geometry of these iridium hydrides, while stoichiometric and catalytic experiments with the isolated complexes provide evidence for the mechanistic proposal. The proposed mechanism explains why the catalytic reaction is slower for unhindered substrates and why small changes in the ligand set drastically alter catalyst activity.
A Novel Ring Expansion Reaction in the Reduction of Benzylic Methoxyamines with Lithium Aluminium Hydride
Booth, Susan E.,Jenkins, Paul R.,Swain, Christopher J.
, p. 147 - 148 (1993)
Reduction of the N-O bonds of benzylic hydroxylamines with lithium aluminium hydride gives a novel ring expansion reaction that can be explained by a radical mechanism.
Highly enantioselective iridium-catalyzed hydrogenation of quinoline derivatives using chiral phosphinite H8-BINAPO
Kim, Hung Lam,Xu, Lijin,Feng, Lichun,Fan, Qing-Hua,Fuk, Loi Lam,Lo, Wai-Hung,Chan, Albert S. C.
, p. 1755 - 1758 (2005)
The chiral diphosphinite H8-BINAPO derived from H8-BINOL has been used in the Ir-catalyzed asymmetric hydrogenation of quinolines, and high enantioselectivity (up to 97% ee) was obtained. Immobilization of the iridium catalyst in poly(ethylene glycol) dimethyl ether (DMPEG) is also discussed. With DMPEG/hexane biphasic system, better enantioselectivities were obtained as compared to those observed in aprotic organic solvents.
Air-stable Ir-(P-Phos) complex for highly enantioselective hydrogenation of quinolines and their immobilization in poly(ethylene glycol) dimethyl ether (DMPEG)
Xu, Lijin,Lam, Kim Hung,Ji, Jianxin,Wu, Jing,Fan, Qing-Hua,Lo, Wai-Hung,Chan, Albert S. C.
, p. 1390 - 1392 (2005)
An air-stable catalyst system Ir-(P-Phos) catalyst was found to be highly effective in the asymmetric hydrogenation of quinoline derivatives. The catalyst immobilized in DMPEG was efficiently recovered and reused eight times, retaining reactivity and enan
Novel Ir-SYNPHOS and Ir-DIFLUORPHOS catalysts for asymmetric hydrogenation of quinolines
Deport, Coralie,Buchotte, Marie,Abecassis, Keren,Tadaoka, Hiroshi,Ayad, Tahar,Ohshima, Takashi,Genet, Jean-Pierre,Mashima, Kazushi,Ratovelomanana-Vidal, Virginie
, p. 2743 - 2747 (2007)
Novel Ir-SYNPHOS and Ir-DIFLUORPHOS catalysts were synthesized and used for the synthesis of tetrahydroquinolines via asymmetric hydrogenation of the corresponding quinoline derivatives. Georg Thieme Verlag Stuttgart.
Efficient enantioselective hydrogenation of quinolines catalyzed by conjugated microporous polymers with embedded chiral BINAP ligand
Wang, Xu,Li, Jun,Lu, Shengmei,Liu, Yan,Li, Can
, p. 1170 - 1174 (2015)
Chiral Ir complexes were successfully used in the asymmetric hydrogenation of olefins, ketones, and quinolines. However, almost all the catalytic systems could not tolerate a high catalyst loading because of the formation of an irreversible iridium dimer and trimer during the reaction. It is expected that higher catalytic activity may be achieved if the Ir-complexes were isolated in space. The development of conjugated microporous polymers (CMPs) gives the opportunity for the spatial separation of the complexes. A series of chiral CMPs based on the chiral (R)-BINAP ligand (BINAP-CMPs) with different surface areas were synthesized. The BINAP ligands were separately distributed in the framework and were three times more active than the homogeneous catalyst (TOF 340 h-1 VS 100 h-1) for the asymmetric hydrogenation of quinolines.
Iridium-catalyzed asymmetric transfer hydrogenation of quinolines with Hantzsch esters
Wang, Da-Wei,Zeng, Wei,Zhou, Yong-Gui
, p. 1103 - 1107 (2007)
The iridium-catalyzed enantioselective transfer hydrogenation of quinolines with Hantzsch esters was developed with up to 88% ee using [Ir(COD)Cl]2/(S)-SegPhos/I2 as a catalyst.
The development of double axially chiral phosphoric acids and their catalytic transfer hydrogenation of quinolines
Guo, Qun-Sheng,Du, Da-Ming,Xu, Jiaxi
, p. 759 - 762 (2008)
(Chemical Equation Presented) Building a better scaffold: Low loadings (0.2-1 mol%) of new double axially chiral phosphoric acid catalysts 1 based on bisbinol scaffold were used for asymmetric transfer hydrogenation. 2-Aryl- and 2-alkyl-substituted quinolines gave tetrahydroquinolines in excellent yields and with up to 98% ee and 2,3-disubstituted tetrahydroquinolines were prepared in high diastereo- and enantioselectivities (up to > 20:1 and 92% ee).
Asymmetric hydrogenation of heteroaromatic compounds mediated by iridium-(P-OP) complexes
Nunez-Rico, Jose L.,Fernandez-Perez, Hector,Benet-Buchholz,Vidal-Ferran, Anton
, p. 6627 - 6631 (2010)
A library of modular iridium complexes derived from P-OP ligands has been evaluated in iridium-mediated asymmetric hydrogenations of heteroaromatic compounds. The "lead" catalysts efficiently catalyzed the hydrogenation of several substituted quinolines and one quinoxaline (10 examples, up to 92% ee).
The use of phosphite-type ligands in the Ir-catalyzed asymmetric hydrogenation of heterocyclic compounds
Lyubimov, Sergey E.,Ozolin, Dmitry V.,Ivanov, Pavel Yu,Melman, Artem,Velezheva, Valeriya S.,Davankov, Vadim A.
, p. 56 - 60 (2014)
A series of chiral phosphite-type ligands was tested in asymmetric Ir-catalyzed hydrogenation of quinolines and 2,4,5,6-tetrahydro-1H-pyrazino(3,2, 1-j,k)carbazole. Hydrogenation of quinaldine hydrochloride provided superior enantioselectivity up to 65% ee compared to quinaldine free base. The ligands were tested for the first time in the asymmetric Ir-Ircatalyzed hydrogenation of 2,4,5,6-tetrahydro-1H-pyrazino(3,2,1-j,k)carbazole yielding the antidepressant drug, pirlindole. Chirality 26:56-60, 2013. 2013 Wiley Periodicals, Inc.
