- Enzymatic Primary Amination of Benzylic and Allylic C(sp3)-H Bonds
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Aliphatic primary amines are prevalent in natural products, pharmaceuticals, and functional materials. While a plethora of processes are reported for their synthesis, methods that directly install a free amine group into C(sp3)-H bonds remain unprecedented. Here, we report a set of new-to-nature enzymes that catalyze the direct primary amination of C(sp3)-H bonds with excellent chemo-, regio-, and enantioselectivity, using a readily available hydroxylamine derivative as the nitrogen source. Directed evolution of genetically encoded cytochrome P411 enzymes (P450s whose Cys axial ligand to the heme iron has been replaced with Ser) generated variants that selectively functionalize benzylic and allylic C-H bonds, affording a broad scope of enantioenriched primary amines. This biocatalytic process is efficient and selective (up to 3930 TTN and 96percent ee), and can be performed on preparative scale.
- Jia, Zhi-Jun,Gao, Shilong,Arnold, Frances H.
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supporting information
p. 10279 - 10283
(2020/07/27)
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- The enzymatic resolution of 1-(4-chlorophenyl)ethylamine by Novozym 435 to prepare a novel triazolopyrimidine herbicide
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The kinetic resolution of (R,S)-1-(4-chlorophenyl)ethylamine was accomplished using a commercial lipase from Candida antarctica (Novozym 435). The performance of this lipase was investigated for the enantioselective amidation of (R,S)-1-(4-chlorophenyl)ethylamine, leaving the target product (S)-1-(4-chlorophenyl)ethylamine in its unreacted form. The effects of various types of solvents and an acyl donor, the molar ratio of the substrate to the acyl donor, and the reaction temperature were studied. The optimum reaction conditions were found to result in amidation with methyl 2-tetrahydrofuroate at 40°C in methyl tert-butyl ether, with a substrate/acyl donor molar ratio of 1:2.4. The conversion rate of (R,S)-1-(4-chlorophenyl)ethylamine was 52%, with an enantiomeric excess of 99% towards the unreacted substrate in a reaction time of 22?hours. Finally, using optically pure (S)-1-(4-chlorophenyl)ethylamine as the raw material, the chemical synthesis of (S)-N-(1-(4-chlorphenyl)ethyl)-2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimidin-2-ylthio)acetamide, a novel triazolopyrimidine herbicide, was achieved, and the total yield and purity were 83.5% and 95.3%, respectively.
- Zhang, Yinjun,Cheng, Feifei,Yan, Hongde,Zheng, Jianyong,Wang, Zhao
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p. 1225 - 1232
(2018/09/25)
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- Optimization of 2-alkoxyacetates as acylating agent for enzymatic kinetic resolution of chiral amines
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In this study, the activity of acetic acid esters modified with electron withdrawing 2-alkoxy-groups was investigated as acylating agent in kinetic resolution (KR) of racemic amines. A homologous series of the isopropyl esters of four 2-alkoxyacetic acids (2-methoxy-, 2-ethoxy-, 2-propoxy- and 2-butoxyacetic acids) were prepared and investigated for enantiomer selective N-acylation, catalyzed by lipase B from Candida antarctica, under batch and continuous-flow conditions. In the first set of experiments, isopropyl 2-propoxyacetate showed the highest effectivity with all of the four racemic amines [(±)-1-phenylethylamine, (±)-4-phenylbutan-2-amine, (±)-heptan-2-amine and (±)-1-methoxypropane-2-amine] in the set enabling excellent conversions (≥46%) and enantiomeric excess values (ee ≥ 99%) with each amines in continuous-flow mode KRs under the optimized reaction conditions. In a second set of experiments, KRs of five additional amines – being substituted derivatives of (±)-1-phenylethylamine – further demonstrated the usefulness of isopropyl 2-propoxyacetate – being the best acylating agent in the first set of KRs – in KRs leading to (R)-N-propoxyacetamides with high ee values (≥99.8%).
- Oláh, Márk,Kovács, Dániel,Katona, Gabriel,Hornyánszky, Gábor,Poppe, László
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p. 3663 - 3670
(2018/06/04)
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- Chirality switching in the crystallization of 1-(4-chlorophenyl) ethylamine with binaphthoic acid by ketimine formation
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Axially chiral binaphthoic acid (BNA) was studied as a resolving agent for a stereoselective crystallization of 1-(4-chlorophenyl)ethylamine (CPEA). The diastereomeric pair of (R)-BNA/(S)-CPEA crystallizes in methylene chloride, on the other hand, the pair of (S)-BNA/(S)-CPEA crystallizes in acetone. The switch of the solubility of the diastereomeric pair is due to the imine formation with acetone. The very low solubility of the BNA/imine pair appears to be responsible for the fast and complete imine formation. The crystal structure of the BNA part in both crystals of the diastereomers maintains a same feature. Asymmetric chiral channels and pockets composed by intermolecular packing of BNA molecules appear in the crystal structures, and the robustness of them seem to contribute to the recognition of the chirality of CPEA with high selectivity.
- Jin, Ying-Ji,Choi, Yunseo,Chen, Qian,Shirbhate, Mukesh Eknath,Huang, Haofei,Kim, Youngmee,Kim, Sung-Jin,Jun, Moo-Jin,Koo, Eon Cheol,Kim, Kwan Mook
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p. 1690 - 1695
(2016/10/13)
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- 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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- A highly fluorescent metallosalalen-based chiral cage for enantioselective recognition and sensing
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A highly fluorescent coordination cage [Zn8L4I 8] has been constructed by treating enantiopure pyridyl- functionalized metallosalalen units (L) with zinc(II) iodide and characterized by a variety of techniques including microanalysis, thermogravimetric analysis (TGA), circular dichroism (CD) spectroscopy, and single-crystal and powder X-ray diffraction. Strong intermolecular π-π, CH-π, and CH-I interactions direct packing of the cage molecules to generate a 3D polycage network interconnected by pentahedral cages formed by adjacent pentamers. The cage has an amphiphilic helical cavity decorated with chiral NH functionalities capable of interactions with guest species such as saccharides. The fluorescence of the cage was greatly enhanced by five enantiomeric saccharides in solution, with enantioselectivity factors of 2.480-4.943, and by five enantiomeric amines in the solid state, with enantioselective fluorescence enhancement ratios of 1.30-3.60. This remarkable chiral sensing of both saccharides and amines with impressive enantioselectivity may result from the steric confinement of the cavity as well as its conformational rigidity. It holds great promise for the development of novel chiral cage materials for sensing applications. Cage-based chiral sensor: A highly fluorescent coordination cage [Zn8L 4I8] can be prepared from enantiopure pyridyl- functionalized metallosalalen units (L). The cage has an amphiphilic helical cavity decorated with chiral NH functionalities and supramolecular interactions generate a 3D polycage network interconnected by pentahedral cages formed by adjacent pentamers (see graphic). The fluorescence of the cage is greatly enhanced either in solution or in the solid state in the presence of enantiomeric saccharides or amines, respectively, with significant enantioselectivity factors.
- Dong, Jinqiao,Zhou, Yanfang,Zhang, Fangwei,Cui, Yong
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supporting information
p. 6455 - 6461
(2014/06/09)
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- Transaminases applied to the synthesis of high added-value enantiopure amines
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Critical parameters affecting the stereoselective amination of (hetero)aromatic ketones using transaminases have been studied, such as temperature, pH, substrate concentration, cosolvent, and source and percentage of amino donor, to further optimize the production of enantiopure amines using both (S)- and (R)-selective biocatalysts from commercial suppliers. Interesting enantiopure amino building blocks have been obtained, overcoming some limitations of traditional chemical synthetic methods. Representative processes were scaled up, affording halogenated and heteroaromatic amines in enantiomerically pure form and good isolated yields.
- Paul, Caroline E.,Rodriguez-Mata, Maria,Busto, Eduardo,Lavandera, Ivan,Gotor-Fernandez, Vicente,Gotor, Vicente,Garcia-Cerrada, Susana,Mendiola, Javier,De Frutos, Oscar,Collado, Ivan
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supporting information
p. 788 - 792
(2014/07/08)
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- Discovery and optimization of orally active cyclohexane-based prolylcarboxypeptidase (PrCP) inhibitors
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The synthesis, SAR, binding affinities and pharmacokinetic profiles are described for a series of cyclohexane-based prolylcarboxypeptidase (PrCP) inhibitors discovered by high throughput screening. Compounds show high levels of ex vivo target engagement in mouse plasma 20 h post oral dose.
- Debenham, John S.,Graham, Thomas H.,Verras, Andreas,Zhang, Yong,Clements, Matthew J.,Kuethe, Jeffrey T.,Madsen-Duggan, Christina,Liu, Wensheng,Bhatt, Urmi R.,Chen, Dunlu,Chen, Qing,Garcia-Calvo, Margarita,Geissler, Wayne M.,He, Huaibing,Li, Xiaohua,Lisnock, Jeanmarie,Shen, Zhu,Tong, Xinchun,Tung, Elaine C.,Wiltsie, Judyann,Xu, Suoyu,Hale, Jeffrey J.,Pinto, Shirly,Shen, Dong-Ming
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p. 6228 - 6233
(2013/11/19)
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- An efficient single-enzymatic cascade for asymmetric synthesis of chiral amines catalyzed by ω-transaminase
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An efficient single-enzymatic cascade approach for the asymmetric synthesis of chiral amines has been developed, which applies the amino donor 3-aminocyclohexa-1,5-dienecarboxylic acid spontaneously tautomerizing to reach reaction completion with excellen
- Wang, Bo,Land, Henrik,Berglund, Per
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supporting information
p. 161 - 163
(2013/02/23)
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- Organocatalytic asymmetric biomimetic transamination of aromatic ketone to optically active amine
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An asymmetric biomimetic transamination of aromatic ketones to optically active amines with o-HOPhCH2NH2 as amine source catalyzed by hydroquinine-derived chiral base is described. Up to 85% ee was obtained.
- Xie, Ying,Pan, Hongjie,Xiao, Xiao,Li, Songlei,Shi, Yian
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supporting information
p. 8960 - 8962,3
(2012/12/12)
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- Organocatalytic asymmetric biomimetic transamination of aromatic ketone to optically active amine
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An asymmetric biomimetic transamination of aromatic ketones to optically active amines with o-HOPhCH2NH2 as amine source catalyzed by hydroquinine-derived chiral base is described. Up to 85% ee was obtained.
- Xie, Ying,Pan, Hongjie,Xiao, Xiao,Li, Songlei,Shi, Yian
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supporting information
p. 8960 - 8962
(2013/01/15)
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- Solvent-free kinetic resolution of primary amines catalyzed by Candida antarctica lipase B: Effect of immobilization and recycling stability
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Highly enantioselective (E >200) N-acylation of nine racemic primary amines with isopropyl methoxyacetate in the presence of Candida antarctica lipase B (Novozym 435) has been reported to yield the unreacted (S)-amines (ee ≥98%) and produced the (R)-amides (ee ≥95%) at 50% conversion under solvent-free conditions. One of the amines and the acyl donor have been used in an equimolar ratio at room temperature (23 °C). Under the reaction conditions, the reuse stability of Novozym 435 with 1-phenylethylamine (as a model compound) has been shown to be poor while somewhat improved stability has been observed with an in-house prepared sol-gel CAL-B catalyst.
- Paeivioe, Mari,Perkioe, Paeivi,Kanerva, Liisa T.
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experimental part
p. 230 - 236
(2012/06/15)
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- COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS
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The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.
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Page/Page column 45-49; 62
(2010/12/31)
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- Halogen-bonding interaction stabilizing cluster-type diastereomeric salt crystals
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O-Ethyl 4-chlorophenylphosphonothioic acid (1) was newly synthesized and applied as a chiral selector for the enantioseparation of racemic l-(4-halophenyl)ethylamines (halo = F, Cl, Br, I; 2a-d) through diastereomeric salt formation. The phosphonothioic acid 1 showed an excellent chirality-recognition ability for the fluorinated and iodinated amines 2a and 2d with the dramatic switch of the absolute configuration of the enantio-enriched isomers in the deposited salts from R for the amine 2a to S for the amine 2d. The X-ray crystallographic analyses of the four pairs of diastereomeric salts revealed that halogen-bonding interaction in the salt crystals plays a very important role for the switch.
- Kobayashi, Yuka,Maeda, Jin,Ando, Tetsuo,Saigo, Kazuhiko
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experimental part
p. 685 - 690
(2011/10/09)
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- Efficient kinetic resolution of racemic amines using a transaminase in combination with an amino acid oxidase
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A range of enantiomerically pure (R)- and (S)-configured chiral amines has been prepared in excellent e.e. (99%) by combining a transaminase enzyme with an amino acid oxidase and catalytic quantities of pyruvate.
- Truppo, Matthew D.,Turner, Nicholas J.,Rozzell, J. David
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supporting information; experimental part
p. 2127 - 2129
(2009/09/06)
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- Resolution of 1-arylalkylamines with 3-O-hydrogen phthalate glucofuranose derivatives: Role of steric bulk in a family of resolving agents
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The development of three new acidic resolving agents which are hydrogen phthalates of 1,2:5,6-di-O-isopropylidene-α-d-glucofuranose 1, 1,2:5,6-di-O-cyclohexylidene-α-d-glucofuranose 2 and 1,2-O- cyclohexylidene-5,6-O-diphenylmethylidene-α-d-glucofuranose 3 is shown for the resolution of 1-arylalkylamines 7a-k. The salts between 1, 2 and (RS)-1-arylalkylamines 7a-k selectively crystallize 1?(S) 7a-j and 2?(S) 7a-h salts, allowing us to recover the corresponding bases (S) 7a-j and (S) 7a-h, respectively, in good yield and enantiomeric excess (73-95% ee). Whereas, the salts between 3 and (RS)-1-arylalkylamines 7a-c,g-i,k selectively crystallize 3?(S)-7a-c,g-i salts to recover the corresponding bases (S)-7a-c,g-i in poor enantiomeric excess (4-35% ee). The difference between the resolving ability of 1 and 2 for 1-arylalkylamines 7a-h is very slight, but there is considerable difference compared to ortho-substituted 1-arylalkylamines 7i and 7j. The role of substituents on a family of resolving agents 1, 2 and 3 is also discussed to interpret their resolving ability.
- Mereyala, Hari Babu,Koduru, Sreenivasulu Reddy,Cheemalapati, Venkata Narasimhaji
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p. 259 - 267
(2007/10/03)
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- Synthesis of enantiopure 6-methoxy-2-naphthylglycolic acid and its application as a resolving agent
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6-Methoxy-2-naphthylglycolic acid (6-MNGA) was designed as a novel acidic resolving agent, on the model of 2-naphthylglycolic acid (2-NGA). Enantiopure 6-MNGA was easily obtained from commercially available 2-bromo-6- methoxynaphthalene through four steps and was found to show a better chiral recognition ability for racemic 1-arylethylamines than the prototype 2-NGA did. The X-ray crystallographic analyses of less-soluble diastereomeric salts revealed that the introduction of a methoxy group at the 6-position of the 2-NGA skeleton made CH/π interaction(s) effective between 6-MNGA molecules and also between the 6-MNGA molecule and the target amine molecule. The methoxy group was also found to contribute to the realization of effective van der Waals interaction. These interactions played important roles for the stabilization of the less-soluble diastereomeric salts to improve the chiral recognition ability of 6-MNGA, compared to that of 2-NGA.
- Shimada, Takayoshi,Kobayashi, Yuka,Saigo, Kazuhiko
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p. 3807 - 3813
(2007/10/03)
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- Resolution of 1-arylalkylamines with 6-(1,2:3,4-di-O-isopropylidene- α-D-galactopyranosyl)hydrogen phthalate
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The resolving ability of a new acidic resolving agent, the hydrogen phthalate of 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose 1, against various 1-arylalkylamines 2a-k is described. Treatment of 1 with amines 2a-f to obtain diastereomeric salts 1·(S)2a-f in 2-propanol allowing the corresponding (S)-amines 2a-f to be recovered in good yield and 61-89% ee. Recrystallization in dichloromethane/hexane, and regeneration gave the amines in enhanced enantiomeric purity (>98% ee). 1 resolved 1-phenylpropylamine 2f in high enantiomeric purity (99% ee) than 1-phenylethylamine 2g (11% ee) and o- and m-methoxy 2h-i, o-chloro-2j and p-fluoro-2k substituted 1-arylamines (11-19% ee). A possible chiral recognition mechanism based on the ability of 1 to exist in two conformations is described.
- Mereyala, Hari Babu,Fatima, Liyakat,Pola, Pallavi
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p. 585 - 587
(2007/10/03)
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- A new hydrogen-bonding motif for chiral recognition in the diastereomeric salts of racemic 1-phenylethylamine derivatives with enantiopure O-ethyl phenylphosphonothioic acid
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(Chemical Equation Presented) An enantiopure phosphonothioic acid showed a unique and superior chiral recognition ability, arising from its P-stereogenicity, for racemic 1-phenylethylamine derivatives through diastereomeric crystallization. Spherical molecular clusters, associated by hydrogen bonds and CH/π interactions, aggregated with high symmetry in the less-soluble diastereomeric salts.
- Kobayashi, Yuka,Morisawa, Fumi,Saigo, Kazuhiko
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p. 4227 - 4230
(2007/10/03)
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- Resolution of 1-arylethylamines with 5-(1,2-O-isopropylidene-3,6-anhydro- α-D-glucofuranosyl) hydrogen phthalate
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The potential of the hydrogen phthalate of 1,2-O-isopropylidene-3,6- anhydro-α-D-glucofuranose 1 obtainable by the reaction of phthalic anhydride with 1,2-O-isopropylidene-3,6-anhydro-α-D-glucofuranose 8 as a new resolving agent is shown. The salts between 1 and (RS)-1-arylethylamines 2-6 and (RS)-1-arylpropylamine 7 selectively crystallize 1·(R)-salts allowing the recovery of the corresponding (R)-amines 2-7. The more soluble 1·(S)-salts were analogously processed to obtain (S)-amines, respectively. In all of the cases (R)- and (S)-amines 2-7 were obtained in high chemical yield and enantiomeric excess >98%. Resolving agent 1 has been recovered in a quantitative yield and high purity.
- Mereyala, Hari Babu,Pola, Pallavi
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p. 2683 - 2685
(2007/10/03)
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- Highly Enantioselective Hydrogen-Transfer Reductive Amination: Catalytic Asymmetric Synthesis of Primary Amines
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Ammonium formate is the hydrogen source in the catalytic asymmetric reductive amination of ketones presented here (Leuckart-Wallach-type reaction). The reaction proceeds smoothly in methanol in the presence of Ir, Rh, and Ru catalysts. Primary amines were obtained as products in good yields with high enantioselectivities after hydrolytic workup when [((R)-tol-binap) RuCl 2] was used as the catalyst (see scheme). R1, R 2=alkyl, aryl.
- Kadyrov, Renat,Riermeier, Thomas H.
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p. 5472 - 5474
(2007/10/03)
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- Synthesis of enantiomerically pure amino-substituted fused bicyclic rings
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This invention describes various processes for synthesis and resolution of racemic amino-substituted fused bicyclic ring systems. One process utilizes selective hydrogenation of an amino-substituted fused bicyclic aromatic ring system. An alternative process prepares the racemic amino-substituted fused bicyclic ring system via nitrosation. In addition, the present invention describes the enzymatic resolution of a racemic mixture to produce the (R)- and (S)-forms of amino-substituted fused bicyclic rings as well as a racemization process to recycle the unpreferred enantioner. Further provided by this invention is an asymmetric synthesis of the (R)- or (S)-enantiomer of primary amino-substituted fused bicyclic ring systems.
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- Process for preparing optically active amines and optically active carboxylic acids, and intermediates for preparation
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Disclosed is a process for preparing an optically active 1-aryl- or 2-aryl-alkylamines of formulas Ia, Ib and Ic with high optical purity and high yield. The process uses an optically active 1- or 2-naphthylglycolic acid of the general formula II as a resolving agent. Also disclosed is a process for praparing an optically active 1- or 2-naphthylglycolic acid of formula II using an optically active 1-aryl- or 2-aryl-alkylamines of formulas Ia, Ib and Ic as the resolving agents
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- Ruthenium-catalysed asymmetric hydrosilylation of ketoximes using chiral oxazolinylferrocenylphosphines
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Chiral ruthenium(II) complexes, RuCl2(PPh3)(oxazolinylferrocenylphosphine), have been found to be effective catalysts for asymmetric hydrosilylation of ketoximes to give the corresponding primary amines in good yields with high enant
- Takei,Nishibayashi,Ishii,Mizobe,Uemura,Hidai
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p. 2360 - 2361
(2007/10/03)
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- A high-performance, tailor-made resolving agent: Remarkable enhancement of resolution ability by introducing a naphthyl group into the fundamental skeleton1
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A novel resolving agent, 2-naphthylglycolic acid (2-NGA), was designed for p-substituted 1-arylethylamines on the basis of the consideration that a rigid and large naphthyl group would be favorable for the close packing of supramolecular hydrogen-bond sheets formed between the carboxy groups of 2-NGA and the amino groups of p-substituted 1-arylethylamines. Racemic 2-NGA was readily available from commercially available raw materials, and both enantiopure forms could be obtained by simple diastereomeric resolution with enantiopure 1-phenyl-ethylamine. Thus-prepared enantiopure 2-NGA was found to have an excellent resolution ability not only for p-substituted 1-arylethylamines, but also for a wide variety of chiral primary amines. X-Ray crystallographic analyses of the less- and more-soluble diastereomeric salts revealed that this excellent resolution ability of 2-NGA arose from the formation of a supramolecular hydrogen-bond sheet with the primary amine, as we had expected, and also from the possible achievement of an infinite chain of CH... π interaction between its naphthyl group and the aromatic group of the amine, which was formed in the hydrophobic region of the supramolecular hydrogen-bond sheet.
- Kinbara, Kazushi,Harada, Yoshiko,Saigo, Kazuhiko
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p. 1339 - 1347
(2007/10/03)
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- (2-naphthyl)glycolic acid: A tailored resolving agent for p-substituted 1-arylethylamines
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A tailored resolving agent for p-substituted l-arylethylamines, which was designed on the basis of a criterion derived from our crystal-structure study, namely that the racemate and the resolving agent should have similar molecular lengths, is described. The designed enantiopure (2- naphthyl)glycolie acid (2-NGA) showed excellent resolving ability for a wide variety of p-substituted l-arylethylamines.
- Kinbara, Kazushi,Harada, Yoshiko,Saigo, Kazuhiko
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p. 2219 - 2222
(2007/10/03)
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- Reduction of amines with isopropylidene glycerol hydrogen phthalate
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The hydrogen phthalate of isopropylidene glycerol has been recently described as an efficient resolving agent of 1-arylethylamines. In order to gain more information on its versatility and to develop a rationale which accounts for its effectiveness, further 1-arylethylamines and other racemic amines were subjected to the same resolution process. A preliminary qualitative analysis of the results reported herein allows to identify some structural features of the aminic substrates conditioning the feasibility of the resolution.
- Pallavicini, Marco,Valoti, Ermanno,Villa, Luigi,Piccolo, Oreste
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p. 1069 - 1073
(2007/10/03)
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- Asymmetric recognition of 1-arylethylamines by (R)-phenylglycyl-(R)-phenylglycine and its mechanism
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An unprotected dipeptide, (R)-phenylglycyl-(R)-phenylglycine, which is insoluble in water, was shown to be an excellent resolving reagent for racemic 1-arylethylamines. By simply stirring the mixture of the dipeptide and racemic 1-phenylethylamine in presence of water, asymmetric recognition occurred to give a salt of (S)-1-phenylethylamine (95% ee) and the dipeptide. X-Ray crystallographic study of the salt elucidated the crystal structure of the diastereomeric salt, where hydrogen bonding and hydrophobic interaction between the dipeptide and amines play important roles in the construction of layers.
- Akazome, Motohiro,Matsuno, Hirozumi,Ogura, Katsuyuki
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p. 2331 - 2336
(2007/10/03)
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- OPTICALLY ACTIVE F-2-ISOPROPOXYPROPIONIC ACID: A NOVEL DERIVATIZING AGENT FOR GAS CHROMATOGRAPHIC ANALYSIS
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F-2-Isopropoxypropionic acid (PIPA) was resolved into enantiomers via its diastereomeric (+)-1-phenylethylamide. (+)-F-2-Isopropoxypropionyl derivatives of several chiral 1-arylalkylamines and α-amino acids were effectively resolved by gas chromatography at low temperature.
- Kawa, Hajimu,Yamaguchi, Fumihiko,Ishikawa, Nobuo
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p. 745 - 748
(2007/10/02)
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