- Decarboxylative cross-nucleophile coupling via ligand-to-metal charge transfer photoexcitation of Cu(ii) carboxylates
-
Reactions that enable carbon–nitrogen, carbon–oxygen and carbon–carbon bond formation lie at the heart of synthetic chemistry. However, substrate prefunctionalization is often needed to effect such transformations without forcing reaction conditions. The development of direct coupling methods for abundant feedstock chemicals is therefore highly desirable for the rapid construction of complex molecular scaffolds. Here we report a copper-mediated, net-oxidative decarboxylative coupling of carboxylic acids with diverse nucleophiles under visible-light irradiation. Preliminary mechanistic studies suggest that the relevant chromophore in this reaction is a Cu(ii) carboxylate species assembled in situ. We propose that visible-light excitation to a ligand-to-metal charge transfer (LMCT) state results in a radical decarboxylation process that initiates the oxidative cross-coupling. The reaction is applicable to a wide variety of coupling partners, including complex drug molecules, suggesting that this strategy for cross-nucleophile coupling would facilitate rapid compound library synthesis for the discovery of new pharmaceutical agents. [Figure not available: see fulltext.].
- Li, Qi Yukki,Gockel, Samuel N.,Lutovsky, Grace A.,DeGlopper, Kimberly S.,Baldwin, Neil J.,Bundesmann, Mark W.,Tucker, Joseph W.,Bagley, Scott W.,Yoon, Tehshik P.
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- Biocatalytic, Intermolecular C?H Bond Functionalization for the Synthesis of Enantioenriched Amides
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Directed evolution of heme proteins has opened access to new-to-nature enzymatic activity that can be harnessed to tackle synthetic challenges. Among these, reactions resulting from active site iron-nitrenoid intermediates present a powerful strategy to forge C?N bonds with high site- and stereoselectivity. Here we report a biocatalytic, intermolecular benzylic C?H amidation reaction operating at mild and scalable conditions. With hydroxamate esters as nitrene precursors, feedstock aromatic compounds can be converted to chiral amides with excellent enantioselectivity (up to >99 % ee) and high yields (up to 87 %). Kinetic and computational analysis of the enzymatic reaction reveals rate-determining nitrenoid formation followed by stepwise hydrogen atom transfer-mediated C?H functionalization.
- Arnold, Frances H.,Athavale, Soumitra V.,Gao, Shilong,Hirschi, Jennifer S.,Liu, Zhen,Mallojjala, Sharath Chandra
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supporting information
p. 24864 - 24869
(2021/10/15)
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- Merging NiH Catalysis and Inner-Sphere Metal-Nitrenoid Transfer for Hydroamidation of Alkynes
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The formal hydroamination/hydroamidation utilizing metal hydride is an appealing synthetic tool for the construction of valuable nitrogen-containing compounds from unsaturated hydrocarbons. While significant advances have been made for the functionalizations of alkenes in this realm, the direct hydroamidation of alkynes remains rather limited due to the high feasibility of the key metal-alkenyl intermediate to choose other reaction pathways. Herein, we report a NiH-catalyzed strategy for the hydroamidation of alkynes with dioxazolones, which allows convenient access to synthetically useful secondary enamides in (E)-anti-Markovnikov or Markovnikov selectivity. The reaction is viable for both terminal and internal alkynes and is also tolerant with a range of subtle functional groups. With H2O found as an essential component for high catalyst turnovers, the involvement of inner-sphere nitrenoid transfer is proposed that outcompetes an undesired semireduction process, thus representing the first example to show the competence of Ni catalysis for metal-nitrenoid formation from dioxazolones.
- Lyu, Xiang,Zhang, Jianbo,Kim, Dongwook,Seo, Sangwon,Chang, Sukbok
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p. 5867 - 5877
(2021/05/06)
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- C-H Amination via Electrophotocatalytic Ritter-Type Reaction
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A method for C-H bond amination via an electrophotocatalytic Ritter-Type reaction is described. The reaction is catalyzed by a trisaminocyclopropenium (TAC) ion in an electrochemical cell under irradiation. These conditions convert benzylic C-H bonds to acetamides without the use of a stoichiometric chemical oxidant. A range of functionality is shown to be compatible with this transformation, and several complex substrates are demonstrated.
- Lambert, Tristan H.,Shen, Tao
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supporting information
p. 8597 - 8602
(2021/06/28)
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- Combined Theoretical and Experimental Studies Unravel Multiple Pathways to Convergent Asymmetric Hydrogenation of Enamides
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We present a highly efficient convergent asymmetric hydrogenation of E/Z mixtures of enamides catalyzed by N,P-iridium complexes supported by mechanistic studies. It was found that reduction of the olefinic isomers (E and Z geometries) produces chiral amides with the same absolute configuration (enantioconvergent hydrogenation). This allowed the hydrogenation of a wide range of E/Z mixtures of trisubstituted enamides with excellent enantioselectivity (up to 99% ee). A detailed mechanistic study using deuterium labeling and kinetic experiments revealed two different pathways for the observed enantioconvergence. For α-aryl enamides, fast isomerization of the double bond takes place, and the overall process results in kinetic resolution of the two isomers. For α-alkyl enamides, no double bond isomerization is detected, and competition experiments suggested that substrate chelation is responsible for the enantioconvergent stereochemical outcome. DFT calculations were performed to predict the correct absolute configuration of the products and strengthen the proposed mechanism of the iridium-catalyzed isomerization pathway.
- Yang, Jianping,Massaro, Luca,Krajangsri, Suppachai,Singh, Thishana,Su, Hao,Silvi, Emanuele,Ponra, Sudipta,Eriksson, Lars,Ahlquist, M?rten S. G.,Andersson, Pher G.
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supporting information
p. 21594 - 21603
(2021/12/27)
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- Chemoselective formation of C–N bond in wet acetonitrile using amberlyst-15(H) as a recyclable catalyst
-
An economically efficient and environmentally benign protocol for the chemoselective one-pot synthesis of diversely N-substituted amides has been developed in good yield through the reaction of benzylic secondary alcohols as well as aliphatic tertiary alcohols and alkyl/aryl nitriles. Commercially available Amberlyst-15(H) has been utilized at 80 °C as an air-stable and reusable heterogeneous inexpensive solid acid catalyst without any anhydrous and inert environment. The attractive features of the present synthetic protocol are mild reaction conditions, short reaction time, excellent chemoselectivity, high atom economy and tolerance of various sensitive moieties.
- Nandy, Sneha,Das, Asit Kumar,Bhar, Sanjay
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supporting information
p. 3326 - 3336
(2020/08/13)
-
- Generation of amine dehydrogenases with increased catalytic performance and substrate scope from ε-deaminating L-Lysine dehydrogenase
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Amine dehydrogenases (AmDHs) catalyse the conversion of ketones into enantiomerically pure amines at the sole expense of ammonia and hydride source. Guided by structural information from computational models, we create AmDHs that can convert pharmaceutically relevant aromatic ketones with conversions up to quantitative and perfect chemical and optical purities. These AmDHs are created from an unconventional enzyme scaffold that apparently does not operate any asymmetric transformation in its natural reaction. Additionally, the best variant (LE-AmDH-v1) displays a unique substrate-dependent switch of enantioselectivity, affording S- or R-configured amine products with up to >99.9% enantiomeric excess. These findings are explained by in silico studies. LE-AmDH-v1 is highly thermostable (Tm of 69 °C), retains almost entirely its catalytic activity upon incubation up to 50 °C for several days, and operates preferentially at 50 °C and pH 9.0. This study also demonstrates that product inhibition can be a critical factor in AmDH-catalysed reductive amination.
- Tseliou, Vasilis,Knaus, Tanja,Masman, Marcelo F.,Corrado, Maria L.,Mutti, Francesco G.
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- Environmentally Benign Ritter Reaction Using Bismuth Salts as a Catalyst
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We developed an environmentally benign Ritter reaction of alcohols with nitriles using a commercially available bismuth salt as a less harmful catalyst. The detailed reaction profiles revealed that consumption of the ether by-product as the reaction proceeded was the key for optimizing this reaction, and the yield of the target amide was improved by adding a small amount of water. This finding clearly reveals the significance of using a bismuth salt as the catalyst, as it is not deactivated in the presence of water. This catalyst system has a broad substrate scope, and even with 1 mol-% of the catalyst, the reaction progresses smoothly. It is also possible to react stoichiometric amounts of nitriles and alcohols, thus reducing the amount of organic solvent required for the reaction. Furthermore, as the inexpensive bismuth catalyst can be easily removed using aqueous hydrochloric acid, a purification process that only required washing and drying without any organic solvents was successfully established.
- Ueno, Masaharu,Kusaka, Ryo,Ohmura, Satoshi D.,Miyoshi, Norikazu
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supporting information
p. 1796 - 1800
(2019/02/07)
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- Asymmetric Synthesis of Chiral Primary Amines by Ruthenium-Catalyzed Direct Reductive Amination of Alkyl Aryl Ketones with Ammonium Salts and Molecular H2
-
A ruthenium/C3-TunePhos catalytic system has been identified for highly efficient direct reductive amination of simple ketones. The strategy makes use of ammonium acetate as the amine source and H2 as the reductant and is a user-friendly and operatively simple access to industrially relevant primary amines. Excellent enantiocontrol (>90% ee for most cases) was achieved with a wide range of alkyl aryl ketones. The practicability of this methodology has been highlighted by scalable synthesis of key intermediates of three drug molecules. Moreover, an improved synthetic route to the optimal diphosphine ligand C3-TunePhos is also presented.
- Tan, Xuefeng,Gao, Shuang,Zeng, Weijun,Xin, Shan,Yin, Qin,Zhang, Xumu
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supporting information
p. 2024 - 2027
(2018/02/19)
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- Stereoselective amination of racemic sec-alcohols through sequential application of laccases and transaminases
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A one-pot/two-step bienzymatic asymmetric amination of secondary alcohols is disclosed. The approach is based on a sequential strategy involving the use of a laccase/TEMPO catalytic system for the oxidation of alcohols into ketone intermediates, and their following transformation into optically enriched amines by using transaminases. Individual optimizations of the oxidation and biotransamination reactions have been carried out, studying later their applicability in a concurrent process. Therefore, 17 racemic (hetero) aromatic sec-alcohols with different substitutions in the aromatic ring have been converted into enantioenriched amines with good to excellent selectivities (90-99% ee) and conversion values (67-99%). The scalability of the process was also demonstrated when two different amine donors were used in the transamination step, such as isopropylamine and cis-2-buten-1,4-diamine. Satisfyingly, both sacrificial amine donors can shift the equilibrium toward the amine formation, leading to the corresponding isolated enantioenriched amines with good to excellent results.
- Martínez-Montero, Lía,Gotor, Vicente,Gotor-Fernández, Vicente,Lavandera, Iván
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supporting information
p. 474 - 480
(2017/06/23)
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- Iron-Catalyzed Carboamination of Olefins: Synthesis of Amines and Disubstituted β-Amino Acids
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Intermolecular carboamination of olefins with general alkyl groups is an unsolved problem. Diastereoselective carboamination of acyclic olefins represents an additional challenge in intermolecular carboaminations. We have developed a general alkylamination of vinylarenes and the unprecedented diastereoselective anti-carboamination of unsaturated esters, generating amines and unnatural β-amino acids. This alkylamination is enabled by difunctional alkylating reagents and the iron catalyst. Alkyl diacyl peroxides, readily synthesized from aliphatic acids, serve as both alkylating reagents and internal oxidizing agents. A computational study suggests that addition of a nitrile to the carbocation is the diastereoselectivity-determining step, and hyperconjugation is proposed to account for the highly diastereoselective anti-carboamination.
- Qian, Bo,Chen, Shaowei,Wang, Ting,Zhang, Xinhao,Bao, Hongli
-
supporting information
p. 13076 - 13082
(2017/09/26)
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- An unexpected copper-catalyzed carbonylative acetylation of amines
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A novel copper-catalyzed carbonylative acetylation of amines has been developed. With peroxide as the oxidant as well as the methyl source with a copper catalyst under CO pressure, good yields of N-acetyl amides could be obtained. Notably, this is the first example of carbonylative acetylation.
- Li, Yahui,Wang, Changsheng,Zhu, Fengxiang,Wang, Zechao,Fran?ois Soulé, Jean,Dixneuf, Pierre H.,Wu, Xiao-Feng
-
supporting information
p. 142 - 144
(2016/12/27)
-
- A Single Lipase-Catalysed One-Pot Protocol Combining Aminolysis Resolution and Aza-Michael Addition: An Easy and Efficient Way to Synthesise β-Amino Acid Esters
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A novel one-pot protocol combining aza-Michael addition and aminolysis resolution was developed to obtain chiral β-amino acid esters with lipase B from Candida antarctica (CAL-B) as the only catalyst. This method is conducted under mild reaction conditions and is very easy to handle. After a series of detailed optimization studies, ten racemic aromatic or aliphatic amines were subjected to this one-pot procedure, and twelve chiral β-amino acid esters and ten chiral amides were successfully synthesised with excellent ee values in theoretical yields. Scaled-up procedures also worked without apparent reduction in reaction rate or enantioselectivity, which makes this method suitable for large-scale production of chiral β-amino acid esters. A one-pot protocol for simultaneous synthesis of chiral β-amino acid esters and amides was developed by combining single lipase B from Candida antarctica (CAL-B) catalysed aza-Michael addition and aminolysis resolution. This method requires mild reaction conditions and is very easy to handle. Chiral β-amino acid esters and chiral amides were obtained with excellent ee values and in theoretical yields.
- Xu, Fan,Wu, Qiongsi,Chen, Xiaoyang,Lin, Xianfu,Wu, Qi
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p. 5393 - 5401
(2015/08/24)
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- One-pot stibine modified Co2(CO)8 catalyzed reductive N-alkylation of primary amides with carbonyl compounds
-
A one-pot stibine modified Co2(CO)8 homogeneous catalytic reductive N-alkylation of primary amides using aldehydes/ketones as alkylating agents, is reported. Good to excellent yields of a wide range of secondary amides are obtained (up to 97%) under relative mild conditions.
- Rubio-Pérez, Laura,Sharma, Pankaj,Pérez-Flores, F. Javier,Velasco, Luis,Arias, J. Luis.,Cabrera, Armando
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experimental part
p. 2342 - 2348
(2012/04/10)
-
- Ritter reaction in subcritical water: An efficient and green method for amides synthesis
-
Ritter reaction was carried out efficiently in subcritical water with catalytic amount of trifluoromethanesulfonic acid. The amides were formed in good to excellent yields from secondary alcohols and tert-butanol with various nitriles.
- Jiang, Shengqian,Wang, Zhouyu,Jiang, Zhenju,Li, Jianhui,Zhou, Shulin,Pu, Long
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experimental part
p. 24 - 28
(2012/08/08)
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- Cyclohexylamine oxidase as a useful biocatalyst for the kinetic resolution and dereacemization of amines
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The biocatalytic performance of a cloned cyclohexylamine oxidase derived from Brevibacterium oxydans IH-35A towards structurally different amines was investigated. Cycloalkyl primary amines, alkyl aryl amines, and α-carbon-substituted aliphatic amines were identified as suitable substrates for the biocatalyst based on an activity assay. Kinetic resolutions of several amines by either recombinant whole cells or crude enzyme extracts prepared therefrom gave enantiomerically pure (R)-amines besides the corresponding ketones. When cyclohexylamine oxidase in combination with a borane-ammonia complex as reducing agent was applied to the deracemization of several substrates, excellent enantiomeric ratios (>99:1) and good isolated yields (62%-75%) of the corresponding (R)-amines were obtained.
- Leisch, Hannes,Grosse, Stephan,Iwaki, Hiroaki,Hasegawa, Yoshie,Lau, Peter C.K.
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experimental part
p. 39 - 45
(2012/03/07)
-
- The Ritter reaction under incredibly green protocol: Nano magnetically silica-supported Br?nsted acid catalyst
-
HClO4-functionalized silica-coated magnetic nanoparticles [γ-Fe2O3@SiO2-HClO4] (2.5 mol%) has been found to be a capable biocompatible and recyclable catalyst for highly efficient conversion of a variety of alcohols to corresponding amides via modified Ritter reaction in good to excellent yields. Since this heterogeneous catalyst can be simply removed by using an external magnetic device then recovered, it also enhances product purity and promises economic.
- Ma'mani, Leila,Heydari, Akbar,Sheykhan, Mehdi
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experimental part
p. 122 - 127
(2010/11/04)
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- Electron-donating and rigid p-stereogenic bisphospholane ligands for highly enantioselective rhodium-catalyzed asymmetric hydrogenations
-
More electron donating, more rigid: A new highly electron-donating P-stereogenic bisphospholane ligand (ZhangPhos) was synthesized in a practical and highly enantioselective manner from a commercially available chiral source. Better or comparable enantioselectivities and reactivities than TangPhos were achieved in rhodium-catalyzed hydrogenation of various functionalized olefins (see scheme; nbd=3,5-norbornadiene). Copyright
- Zhang, Xiaowei,Huang, Kexuan,Hou, Guohua,Cao, Bonan,Zhang, Xumu
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supporting information; experimental part
p. 6421 - 6424
(2010/12/19)
-
- Method for preparing optically active amines
-
The present invention relates to a method of preparing optically active amines and chiral amines prepared thereby. The method includes reacting an amine compound, a metal catalyst, a biocatalyst including a lipase, and an acyl donor compound in an organic solvent to obtain a chiral amide compound, and then hydrolyzing the chiral amide compound to obtain a chiral amine.
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Page/Page column 12
(2009/09/29)
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- Enantioselective hydrogenation of N-H imines
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(Figure Presented) N-H ketoimines 3a-3v are readily prepared in high yield via organometallic addition to nitriles and isolated as corresponding bench-stable hydrochloride salts. Homogeneous asymmetric hydrogenation of unprotected N-H ketoimines 3a-3v usi
- Hou, Guohua,Gosselin, Francis,Li, Wei,McWilliams, J. Christopher,Sun, Yongkui,Weisel, Mark,O'Shea, Paul D.,Chen, Cheng-Yi,Davies, Ian W.,Zhang, Xumu
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supporting information; experimental part
p. 9882 - 9883
(2009/12/06)
-
- A chemoenzymatic approach to enantiomerically pure amines using dynamic kinetic resolution: application to the synthesis of norsertraline
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Racemization catalyst 5c and the enzyme Candida antarctica lipase B were combined in a one-pot dynamic kinetic resolution (DKR) of primary amines in which a wide range of amines were transformed to their corresponding amides in up to 95% isolated yield and > 99% ee. The DKR protocol was applicable with either isopropyl acetate or dibenzyl carbonate as the acyl donor. In the latter case, release of the free amine from the carbamate products was carried out under very mild conditions. The racemization of (S)-1-phenylethylamine with several different Ru catalysts was also evaluated. Catalyst 5c, of the Shvo type, was able to selectively racemize amines and was also compatible with the reaction conditions used for DKR. A racemization study of three different amines with varying electronic properties was also performed. Competitive racemization of a 1:1 mixture of the deuterated and non-deuterated amine was carried out with 5c and a primary kinetic isotope effect was observed for all three amines, providing support that the rate-determining step is β-hydride elimination. The chemoenzymatic DKR protocol was applied to the synthesis of norsertraline (16) by using a novel route starting from readily available 1,2,3,4-tetrahydro- 1-naphthy lamine (1o).
- Thalen, Lisa K.,Zhao, Dongbo,Sortais, Jean-Baptiste,Paetzold, Jens,Hoben, Christine,Baeckvall, Jan-E.
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supporting information; scheme or table
p. 3403 - 3410
(2009/12/29)
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- Novel chiral phosphine-phosphoramidite ligands derived from 1-naphthylamine for highly efficient Rh-catalyzed asymmetric hydrogenation
-
A new chiral phosphine-phosphoramidite ligand (S)-HY-Phos 1 has been prepared from 1-naphthylamine via a two-step transformation, and successfully applied in the Rh-catalyzed asymmetric hydrogenation of various functionalized olefins, including α-(acetamido)cinnamates, enamides and α-enol ester phosphonates, in which up to 98% ee, 99% ee and 99% ee were achieved, respectively.
- Yu, Sai-Bo,Huang, Jia-Di,Wang, Dao-Yong,Hu, Xiang-Ping,Deng, Jun,Duan, Zheng-Chao,Zheng, Zhuo
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p. 1862 - 1866
(2008/12/21)
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- Asymmetric synthesis of optically pure pharmacologically relevant amines employing ω-transaminases
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Various ω-transaminases were tested for the synthesis of enantiomerically pure amines from the corresponding ketones employing D- or L-alanine as amino donor and lactate dehydrogenase to remove the side-product pyruvate to shift the unfavourable reaction equilibrium to the product side. Both enantiomers, (R)- and (S)-amines, could be prepared with up to 99% ee and >99% conversions within 24 h at 50 mM substrate concentration. The activity and stereoselectivity of the amination reaction depended on the ω-transaminase and substrate employed; furthermore the co-solvent significantly influenced both the stereoselectivity and activity of the transaminases. Best results were obtained by employing ATA-117 to obtain the (R)-enantiomer and ATA-113 or ATA-103 to access the (S)-enantiomer with 15% v v-1 DMSO.
- Koszelewski, Dominik,Lavandera, Ivan,Clay, Dorina,Rozzell, David,Kroutil, Wolfgang
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supporting information; experimental part
p. 2761 - 2766
(2009/10/06)
-
- Nonenzymatic kinetic resolution of amines in ionic liquids
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Ionic liquids are remarkably suitable and clean media for performing nonenzymatic kinetic resolution (KR) of amines through enantioselective N-acetylation: high levels of selectivity were obtained with a large variety of amines at room temperature (up to s = 30). Georg Thieme Verlag Stuttgart.
- Sabot, Cyrille,Subhash, Pithani V.,Valleix, Alain,Arseniyadis, Stellios,Mioskowski, Charles
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p. 268 - 272
(2008/09/21)
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- Preparation of new C2-symmetric tetraphosphine ligands for Rh-catalyzed asymmetric hydrogenation of arylenamides
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A new type of chiral tetraphosphine ligands 1 were prepared from enantiopure anti-head-to-head coumarin dimer 5 and then utilized in Rh-catalyzed asymmetric hydrogenation reaction of arylenamides, affording the corresponding amides with up to 85% ee. Some
- Zhao, Dongbo,Wang, Zheng,Ding, Kuiling
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p. 5095 - 5098
(2008/02/09)
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- Asymmetric enamide hydrogenation using planar-chiral cyrhetrenes
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The catalytic asymmetric hydrogenation of α-arylenamides using catalysts prepared in situ from [Rh(cod)2]BF4 and cyrhetrenyldiphosphines was effective with a range of enamides. The corresponding acetamides were obtained with up to 93
- Stemmler, René T.,Bolm, Carsten
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p. 6189 - 6191
(2008/03/12)
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- Asymmetric synthesis of primary amines via the spiroborate-catalyzed borane reduction of oxime ethers
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The enantioselective borane reduction of O-benzyloxime ethers to primary amines was studied under catalytic conditions using the spiroborate esters 5-10 derived from nonracemic 1,2-amino alcohols and ethylene glycol. Effective catalytic conditions were achieved using only 10% of catalyst 5 derived from diphenylvalinol in dioxane at 0°C resulting in complete conversion to the corresponding primary amine in up to 99% ee.
- Huang, Xiaogen,Ortiz-Marciales, Margarita,Huang, Kun,Stepanenko, Viatcheslav,Merced, Francisco G.,Ayala, Angel M.,Correa, Wildeliz,De Jesus, Melvin
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p. 1793 - 1795
(2008/02/02)
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- Dynamic kinetic resolution of primary amines with a recyclable Pd nanocatalyst for racemization
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(Chemical Equation Presented) A practical procedure for the dynamic kinetic resolution (DKR) of primary amines has been developed. This procedure employs a palladium nanocatalyst as the racemization catalyst, a commercial lipase (Novozym-435) as the resol
- Kim, Mahn-Joo,Kim, Won-Hee,Han, Kiwon,Yoon, Kyung Choi,Park, Jaiwook
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p. 1157 - 1159
(2007/10/03)
-
- Chiral bisphospholane ligands (Me-ketalphos): Synthesis of their Rh(I) complexes and applications in asymmetric hydrogenation
-
Rhodium complexes of functionalized bisphospholane ligands (S,S,S,S-Me-ketalphos) 1 and (R,S,S,R-Me-ketalphos) 2 have been used as catalyst precursors for the asymmetric hydrogenation of several different types of functionalized olefins and have achieved
- Dai, Qian,Wang, Chun-Jiang,Zhang, Xumu
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p. 868 - 871
(2007/10/03)
-
- Unsymmetrical ferrocenylethylamine-derived monophosphoramidites: Highly efficient chiral ligands for Rh-catalyzed enantioselective hydrogenation of enamides and α-dehydroamino acid derivatives
-
A new family of unsymmetrical ferrocenylethylamine-derived monophosphoramidites were synthesized and successfully applied in the Rh-catalyzed enantioselective hydrogenation of a range of enamides and α-dehydroamino acid esters, and ee values of up to 99.5% were obtained for both types of substrate. These results suggest that unsymmetrical amine-derived monophosphoramidites can also exhibit excellent enantioselectivity for a broad range of substrates, comparable to or higher than those of the most efficient symmetrical amine-derived monophosphoramidites reported thus far.
- Zeng, Qing-Heng,Hu, Xiang-Ping,Duan, Zheng-Chao,Liang, Xin-Miao,Zheng, Zhuo
-
p. 393 - 396
(2007/10/03)
-
- PROCESS FOR PRODUCING OPTICALLY ACTIVE DIMER OF PHOSPHORUS HETEROCYCLE
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Primary phosphine represented by formula (1): ????????[Chem. 1] R-PH2?????(1) (wherein R represents a linear, branched, or cyclic alkyl group having 2 to 20 carbon atoms) is reacted with a compound represented by formula (2): ????????[Chem. 2]
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Page/Page column 18
(2010/11/08)
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- Six-membered bis(azaphosphorinane), readily available ligand for highly enantioselective asymmetric hydrogenations
-
A new six-membered bis(azaphosphorinane) ligand has been readily prepared starting from an inexpensive chiral epoxide; excellent enantioselectivities (up to over 99% ee) have been achieved in the Rh-catalyzed asymmetric hydrogenations of β-dehydroamino ac
- Yan, Yongjun,Zhang, Xumu
-
p. 1567 - 1569
(2007/10/03)
-
- Readily available, recoverable and soluble polymer-monophosphite ligands for highly enantioselective Rh-catalyzed hydrogenation
-
A new family of readily available, recoverable and soluble polymer-monophosphite ligands were prepared and successfully used in the Rh-catalyzed asymmetric hydrogenation of enamides and β-dehydroamino acid esters, in which up to 99 and 99.9% ee were obtai
- Hu, Xiang-Ping,Huang, Jia-Di,Zeng, Qing-Heng,Zheng, Zhuo
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p. 293 - 295
(2008/02/08)
-
- Unprecedented, fully recyclable, solid-supported reagent for the kinetic resolution of racemic amines through enantioselective N-acetylation
-
The high-yielding synthesis and application of the first polymer supported reagent for the kinetic resolution (KR) of amines through enantioselective acetylation is described; this new supported chiral reagent allows the KR of primary amines with excellent selectivities at room temperature; moreover, this supported approach is highly efficient as the Merrifield-supported chiral scaffold can be quantitatively recovered and recycled. The Royal Society of Chemistry 2005.
- Arseniyadis, Stellios,Subhash, Pithani V.,Valleix, Alain,Wagner, Alain,Mioskowski, Charles
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p. 3310 - 3312
(2007/10/03)
-
- Chemoenzymatic dynamic kinetic resolution of primary amines
-
An efficient process for dynamic kinetic resolution of amines was developed by combining a ruthenium-catalyzed racemization with a lipase-catalyzed resolution. A variety of unfunctionalized primary amines were transformed into one enantiomer of the amide in high yield and high enantioselectivity. Copyright
- Paetzold, Jens,Baeckvall, Jan E.
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p. 17620 - 17621
(2007/10/03)
-
- Tuning the enantioselective N-acetylation of racemic amines: A spectacular salt effect
-
We have described a spectacular salt effect in the kinetic resolution of (±)-1-phenylethylamine, which leads to an increase in reactivity, high levels of selectivity, and a complete reversal of the stereoselectivity. By tuning the reaction conditions, we
- Arseniyadis, Stellios,Subhash, Pithani V.,Valleix, Alain,Mathew, Suju P.,Blackmond, Donna G.,Wagner, Alain,Mioskowski, Charles
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p. 6138 - 6139
(2007/10/03)
-
- Kinetic resolution of amines: A highly enantioselective and chemoselective acetylating agent with a unique solvent-induced reversal of stereoselectivity
-
Solvents lend a hand: Changing the polarity of the reaction solvent from 1,3-dimethyltetrahydropyrimidin-2-one (DMPU) to toluene reverses the stereo-selectivity observed in the acetylation of amines with (1S,2S)-1 (see scheme). Optimizing the reaction conditions led to an unprecedented 90% ee (S) in DMPU at -20°C with a 33% conversion.
- Arseniyadis, Stellios,Valleix, Alain,Wagner, Alain,Mioskowski, Charles
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p. 3314 - 3317
(2007/10/03)
-
- Synthesis and Application of Chiral Phospholane Ligands Bearing a Sterically and Electrically Adjustable Moiety
-
A series of C1-symmetric phosphine-phospholane ligands, 1-(disubstituted phosphino)-2-(phospholano)benzenes (5), which are called UCAPs, with an achiral phosphino group and a chiral phospholane which can be sterically and electrically adjustabl
- Matsumura, Kazuhiko,Shimizu, Hideo,Saito, Takao,Kumobayashi, Hidenori
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p. 180 - 184
(2007/10/03)
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- Process for producing optically active amide from alpha beta- unsaturated amide derivative in the presence of transition metal complex containing phosphine-phosphorane compound and transition metal
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A novel process for producing an optically active amide excellent in chemical selectivity and enantioselectivity by asymmetric hydrogenation of an α,β-unsaturated amide and also allowing the reaction to proceed efficiently even when a trace amount of a catalyst is used relative to the substrate as compared with the amount in a conventional process. An optically active amide is produced by asymmetric hydrogenation of an α,β-unsaturated amide derivative in the presence of a transition metal complex containing a specific phosphine-phosphorane compound.
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- Enantioselective hydrogenation of enamides catalyzed by chiral rhodium-monodentate phosphite complexes
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Chiral monophosphites derived from BINOL are cheap and efficient ligands in the Rh-catalyzed hydrogenation of N-acyl enamides, providing amines with high degrees of enantioselectivity (up to 97.0% ee).
- Reetz, Manfred T.,Mehler, Gerlinde,Meiswinkel, Andreas,Sell, Thorsten
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p. 7941 - 7943
(2007/10/03)
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- Highly enantioselective hydrogenation of enamides catalyzed by rhodium-monodentate phosphoramidite complex
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The monodentate phosphoramidite ligand monophos was used in the Rh-catalyzed asymmetric hydrogenation of enamides to give high enantioselectivities (up to 96% ee).
- Jia, Xian,Guo, Rongwei,Li, Xingshu,Yao, Xinsheng,Chan, Albert S.C
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p. 5541 - 5544
(2007/10/03)
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- Synthesis and first applications of a new family of chiral monophosphine ligand: 2,5-diphenylphosphospholanes
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The cyclic phosphinic acid 1-hydroxy-1-r-oxo-2c,5-t-diphenylphospholane was synthesized and resolved into enantiomers through fractional crystallization of the quinine salts. The P-phenyl, P-methyl and P-benzyl tertiary phosphine oxides were obtained from
- Guillen, Frédéric,Rivard, Michael,Toffano, Martial,Legros, Jean-Yves,Daran, Jean-Claude,Fiaud, Jean-Claude
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p. 5895 - 5904
(2007/10/03)
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- The asymmetric dialkylzinc addition to imines catalyzed by [2.2]paracyclophane-based N,O-ligands
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The first highly enantioselective dialkylzinc addition to imines in the presence of catalytic amounts of N,O-ligands is reported. N-formyl-α-(p-tolysulfonyl)benzylamines are the readily available starting materials easily obtained in a one-pot synthesis from benzaldehydes, formamide, and p-tolylsulfinic acid. Upon deprotonation, the sulfinate is eliminated to give the acyl imine. The acyl imines further react with alkylzinc reagents in the presence of catalytic amounts of [2.2]paracyclophane-based N,O-ligands L* yielding the alkylated N-(1-phenylpropyl)formamides with excellent yields and enantioselectivities. Copyright
- Dahment, Stefan,Braese, Stefan
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p. 5940 - 5941
(2007/10/03)
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- Synthesis of novel chiral binaphthyl phosphorus ligands and their applications in Rh-catalyzed asymmetric hydrogenation
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A series of new chiral mono- or bidentate phosphorus ligands were efficiently prepared through a key intermediate (S)-4-chloro-4,5-dihydro-3H-4-phosphacyclohepta[2,1-a;3,4-a′] binaphthalene and its derivatives. These ligands were applied in the Rh-catalyzed asymmetric hydrogenation of α-dehydro amino acids, enol acetates, itaconates, and enamides. Good to excellent enantioselectivities were obtained (up to 99.5% ee).
- Chi, Yongxiang,Zhang, Xumu
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p. 4849 - 4852
(2007/10/03)
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- Novel 1,4-diphosphanes with imidazolidin-2-one Backbones as chiral ligands: Highly enantioselective Rh-catalyzed hydrogenation of enamides
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Appropriate gauche steric interactions between the N-substituents and the phosphanylmethyl groups (see picture, top right) in the novel 1,4-diphosphane ligands 1 having an imidazolidin-2-one backbone affect the conformational flexibility of the seven-memb
- Lee, Sang-Gi,Zhang, Yong Jian,Song, Choong Eui,Lee, Jae Kyun,Choi, Jung Hoon
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p. 847 - 849
(2007/10/03)
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- A chiral 1,2-bisphospholane ligand with a novel structural motif: Applications in highly enantioselective Rh-catalyzed hydrogenations
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TangPhos (1) is a highly efficient and practical ligand for asymmetric hydrogenations. High enantioselectivities and turnover numbers were observed in the Rh-catalyzed hydrogenation of α-(acylamino) acrylic acids and α-arylenamides.
- Tang, Wenjun,Zhang, Xumu
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p. 1612 - 1614
(2007/10/03)
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- Chiral C2-symmetric ligands with 1,4-dioxane backbone derived from tartrates: Syntheses and applications in asymmetric hydrogenation
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Chiral 1,4-diphenylphosphines 5-7 as well as thioether 8 were synthesized from tartrates employing Ley's "BDA" and "Dispoke" methodologies as the key step. Rhodium(I) complexes with 5-7 are efficient catalysts for the asymmetric hydrogenation of β-substituted enamides and MOM-protected β-hydroxyl enamides, which furnished chiral amines or β-amino alcohols with 94-99% ee. These results indicated that the 1,4-dioxane backbone in the ligands having the general structure 2 played an important role in stabilizing metal-ligand chelate conformation. Higher enantioselectivities with ligand 2 were achieved compared with the analogous ligands having the general structure 1.
- Li, Wenge,Waldkirch, Jason P.,Zhang, Xumu
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p. 7618 - 7623
(2007/10/03)
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- Lipase/palladium-catalyzed asymmetric transformations of ketoximes to optically active amines.
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[reaction: see text] Prochiral ketoximes were asymmetrically transformed to optically active amines in the acetylated forms by coupled lipase/palladium catalysis in the presence of an acyl donor under 1 atm of hydrogen.
- Choi,Kim,Ahn,Kim
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p. 4099 - 4101
(2007/10/03)
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- Synthesis of some ferrocene-based 1,3-bis(phosphanes) with planar chirality as the sole source of chirality
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Several enantiopure diphosphanes 21 were synthesized in three steps from a common precursor 19. The cationic rhodium complexes 22 were screened as catalysts for asymmetric hydrogenation of various alkenes. Enantioselectivities up to 95-98% have been obser
- Argouarch, Gilles,Samuel, Odile,Kagan, Henri B.
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p. 2885 - 2891
(2007/10/03)
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- A new class of ferrocene-based 1,2-bis(phosphanes) possessing only planar chirality
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Chiral 1,2-bis(phosphanes) 13, devoid of individual chiral centers, have been prepared in three steps from chiral sulfoxide 10. Their corresponding rhodium complexes were used as catalysts for asymmetric hydrogenation, giving high ee values (≤ 95%) in the
- Argouarch, Gilles,Samuel, Odile,Riant, Olivier,Daran, Jean-Claude,Kagan, Henri B.
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p. 2893 - 2899
(2007/10/03)
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