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Extending the Substrate Scope for the Asymmetric Iridium‐Catalyzed Hydrogenation of Minimally Functionalized Olefins by Using Biaryl Phosphite‐Based Modular Ligand Libraries 下载免费PDF全文
Asymmetric hydrogenation is one of the most efficient and atom‐economical tools to prepare chiral molecules. However, the enantiodiscrimination of simple, minimally functionalized olefins is still challenging and requires more sophisticated ligand design. Herein, we discuss our progress in the successful development of ligand design for the iridium‐catalyzed asymmetric hydrogenation of minimally functionalized olefins.
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Alejandro Baeza Dr. Andreas Pfaltz Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(13):4003-4009
We have evaluated a wide range of iridium complexes derived from chiral oxazoline‐based N,P ligands for the asymmetric hydrogenation of imines and identified three efficient catalysts. These catalysts are readily synthesized by straightforward convenient routes and are air and moisture stable. In the reduction of acetophenone N‐arylimines and related acyclic substrates, excellent enantioselectivities (up to 96 % ee) were obtained by using 0.1–0.5 mol % of catalyst at ?20 °C and 5–50 bar hydrogen pressure. 相似文献
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Ernest Salomó Dr. Sílvia Orgué Prof. Antoni Riera Prof. Xavier Verdaguer 《Angewandte Chemie (International ed. in English)》2016,55(28):7988-7992
The MaxPHOX–Ir catalyst system provided the highest selectivity ever reported for the reduction of cyclic enamides derived from α‐ and β‐tetralones. This result indicates that iridium catalysts are also proficient in reducing alkenes bearing metal‐coordinating groups. In the present system, selectivity was pressure‐dependent: In most cases, a decrease in the H2 pressure to 3 bar resulted in an increase in enantioselectivity. Moreover, the process can be carried out in environmentally friendly solvents, such as methanol and ethyl acetate, with no loss of selectivity. 相似文献
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Alejandro Baeza Dr. Andreas Pfaltz Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(10):2266-2269
Optically active tertiary amines are readily prepared by iridium‐catalyzed asymmetric hydrogenation of unfunctionalized enamines (see scheme). The best enantioselectivities with >90 % ee were obtained with N‐aryl‐ and N‐benzyl‐substituted enamines with a terminal double bond. The hydrogenation of enamines derived from cyclic ketones, which has not been reported yet with other catalysts, gave enantiomeric excesses of up to 87 %.
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Zhaobin Han Zheng Wang Dr. Xumu Zhang Prof. Dr. Kuiling Ding Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(29):5345-5349
From imines to amines through catalysis by IrI complexes of a new type of P,N ligand (see scheme): This reaction affords the corresponding optically active amines with up to 98 % ee and has also been used with perfect stereoselectivity in the asymmetric synthesis of sertraline ( 1 ), an important antidepressant chiral drug.
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Extending the Substrate Scope of Bicyclic P‐Oxazoline/Thiazole Ligands for Ir‐Catalyzed Hydrogenation of Unfunctionalized Olefins by Introducing a Biaryl Phosphoroamidite Group 下载免费PDF全文
Maria Biosca Dr. Alexander Paptchikhine Dr. Oscar Pàmies Prof. Pher G. Andersson Prof. Montserrat Diéguez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3455-3464
This study identifies a series of Ir‐bicyclic phosphoroamidite–oxazoline/thiazole catalytic systems that can hydrogenate a wide range of minimally functionalized olefins (including E‐ and Z‐tri‐ and disubstituted substrates, vinylsilanes, enol phosphinates, tri‐ and disubstituted alkenylboronic esters, and α,β‐unsaturated enones) in high enantioselectivities (ee values up to 99 %) and conversions. The design of the new phosphoroamidite–oxazoline/thiazole ligands derives from a previous successful generation of bicyclic N‐phosphane–oxazoline/thiazole ligands, by replacing the N‐phosphane group with a π‐acceptor biaryl phosphoroamidite moiety. A small but structurally important family of Ir‐phosphoroamidite–oxazoline/thiazole precatalysts has thus been synthesized by changing the nature of the N‐donor group (either oxazoline or thiazole) and the configuration at the biaryl phosphoroamidite moiety. The substitution of the N‐phosphane by a phosphoroamidite group in the bicyclic N‐phosphane–oxazoline/thiazole ligands extended the range of olefins that can be successfully hydrogenated. 相似文献
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Development of Chiral Spiro P‐N‐S Ligands for Iridium‐Catalyzed Asymmetric Hydrogenation of β‐Alkyl‐β‐Ketoesters 下载免费PDF全文
Deng‐Hui Bao Hui‐Ling Wu Chao‐Lun Liu Prof. Jian‐Hua Xie Prof. Qi‐Lin Zhou 《Angewandte Chemie (International ed. in English)》2015,54(30):8791-8794
The chiral tridentate spiro P‐N‐S ligands (SpiroSAP) were developed, and their iridium complexes were prepared. Introduction of a 1,3‐dithiane moiety into the ligand resulted in a highly efficient chiral iridium catalyst for asymmetric hydrogenation of β‐alkyl‐β‐ketoesters, producing chiral β‐alkyl‐β‐hydroxyesters with excellent enantioselectivities (95–99.9 % ee) and turnover numbers of up to 355 000. 相似文献
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Dr. Agnieszka Bartoszewicz Dr. Nanna Ahlsten Prof. Dr. Belén Martín‐Matute 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(23):7274-7302
The preparation of chiral alcohols and amines by using iridium catalysis is reviewed. The methods presented include the reduction of ketones or imines by using hydrogen (hydrogenations), isopropanol, formic acid, or formate (transfer hydrogenations). Also dynamic and oxidative kinetic resolutions leading to chiral alcohols and amines are included. Selected literature reports from early contributions to December 2012 are discussed. 相似文献
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Iridium‐Catalyzed Enantioselective Hydrogenation of Oxocarbenium Ions: A Case of Ionic Hydrogenation
Tilong Yang Yongjie Sun Heng Wang Zhenyang Lin Jialin Wen Xumu Zhang 《Angewandte Chemie (International ed. in English)》2020,59(15):6108-6114
Ionic hydrogenation has not been extensively explored, but is advantageous for challenging substrates such as unsaturated intermediates. Reported here is an iridium‐catalyzed hydrogenation of oxocarbenium ions to afford chiral isochromans with high enantioselectivities. A variety of functionalities are compatible with this catalytic system. In the presence of a catalytic amount of the Brønsted acid HCl, an α‐chloroether is generated in situ and subsequentially reduced. Kinetic studies suggest first‐order kinetics in the substrate and half‐order kinetics in the catalyst. A positive nonlinear effect, together with the half kinetic order, revealed a dimerization of the catalyst. Possible reaction pathways based on the monomeric iridium catalyst were proposed and DFT computational studies revealed an ionic hydrogenation pathway. Chloride abstraction and the cleavage of dihydrogen occur in the same step. 相似文献
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Jingzhao Xia Dr. Guoqiang Yang Ruijing Zhuge Prof. Dr. Yangang Liu Prof. Dr. Wanbin Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(51):18354-18357
An iridium‐catalyzed asymmetric hydrogenation of unfunctionalized exocyclic C=C bonds was performed by using an axially flexible chiral phosphine–oxazoline ligand, providing the desired chiral 1‐benzyl‐2,3‐dihydro‐1H‐indene products with up to 98 % ee (enantiomeric excess). This represents the first general hydrogenation of unfunctionalized exocyclic olefins with high selectivity reported thus far. The additive acetate ion plays an important role in the reaction's high enantioselectivity. The chiral product can be further transformed into key intermediates required for the synthesis of an important insecticide and a drug compound. 相似文献
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A New Class of Tunable Dendritic Diphosphine Ligands: Synthesis and Applications in the Ru‐Catalyzed Asymmetric Hydrogenation of Functionalized Ketones 下载免费PDF全文
Dr. Baode Ma Tingting Miao Yihua Sun Yanmei He Dr. Ji Liu Dr. Yu Feng Prof. Dr. Hui Chen Prof. Dr. Qing‐Hua Fan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9969-9978
A series of tunable G0–G3 dendritic 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl (BINAP) ligands was prepared by attaching polyaryl ether dendrons onto the four phenyl rings on the P atoms. Their ruthenium complexes were employed in the asymmetric hydrogenation of β‐ketoesters, α‐ketoesters, and α‐ketoamides to reveal the effects of dendron size on the catalytic properties. The second‐ and third‐generation catalysts exhibited excellent enantioselectivities, which are remarkably higher than those obtained from the small molecular catalysts and the first‐generation catalyst. Molecular modeling indicates that the incorporation of bulky dendritic wedges can influence the steric environments around the metal center. In addition, the ruthenium catalyst bearing a second‐generation dendritic ligand could be recycled and reused seven times without any obvious decrease in enantioselectivity. 相似文献
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Javier Mazuela Alexander Paptchikhine Oscar Pàmies Pher G. Andersson Montserrat Diéguez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(15):4567-4576
A library of readily available phosphite–oxazole/thiazole ligands ( L1 a – g – L7 a – g ) was applied in the Ir‐catalyzed asymmetric hydrogenation of several largely unfunctionalized E‐ and Z‐trisubstituted and 1,1‐disubstituted terminal alkenes. The ability of the catalysts to transfer chiral information to the product could be tuned by choosing suitable ligand components (bridge length, the substituents in the heterocyclic ring and the alkyl backbone chain, the configuration of the ligand backbone, and the substituents/configurations in the biaryl phosphite moiety), so that enantioselectivities could be maximized for each substrate as required. Enantioselectivities were therefore excellent (enantiomeric excess (ee) values up to >99 %) for a wide range of E‐ and Z‐trisubstituted and 1,1‐disubstituted terminal alkenes. The biaryl phosphite moiety was a very advantageous ligand component in terms of substrate versatility. 相似文献
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《中国化学》2018,36(9):851-856
A series of novel and easily accessed ferrocene‐based amino‐phosphine‐sulfonamide (f‐Amphamide) ligands have been developed and applied in Ir‐catalyzed asymmetric hydrogenation of aryl ketones, affording the corresponding chiral secondary alcohols with excellent results (up to >99% conversion, >99% ee and TON up to 200 000). DFT calculations suggest an activating model involving an alkali cation Li+. 相似文献
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