- Asymmetric amination of meso-epoxide with vegetable powder as a low-toxicity catalyst
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This paper describes the scope and limitation of substrates subjected to asymmetric amination with epoxides catalyzed by a soluble soybean polysaccharide (Soyafibe S-DN), which we recently discovered from the reaction of 1,2-epoxycyclohexane with cyclopropylamine. Various meso-epoxides reacted with various amines afforded the corresponding products with good enantiomeric selectivity. Since it was found that pectin was found to have a catalytic ability after screening commercially available polysaccharides, we studied 33 different vegetable powders having pectic substances, and we found that many vegetable powders showed catalytic ability. These results should guide in using vegetable components as low-toxic catalysts for the production of pharmaceuticals.
- Asano, Tatsuhiro,Kurata, Hiroyuki,Takeuchi, Yuki,Tsuzaki, Kazuya,Wada, Koichi
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- Highly regioselective ring-opening of epoxides with amines: A metal- A nd solvent-free protocol for the synthesis of β-amino alcohols
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We herein report a metal- A nd solvent-free acetic acid-mediated ring-opening reaction of epoxides with amines. This process provides β-amino alcohols in high yields with excellent regioselectivity. Importantly, this epoxide ring-opening protocol can be used for the introduction of amines in natural products during late-stage transformations.
- Li, Dong,Wang, Jing,Yu, Shibo,Ye, Silei,Zou, Wenjie,Zhang, Hongbin,Chen, Jingbo
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supporting information
p. 2256 - 2259
(2020/03/04)
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- THERAPEUTIC COMPOUNDS AND METHODS OF USE THEREOF
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The invention provides a compound of formula I: or a pharmaceutically acceptable salt thereof, wherein the variables X, Y1-Y5, R1, R2, R3, R4, and Het have the meaning as described herein, and compositions containing such compounds and methods for using such compounds and compositions.
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Paragraph 0653; 0656; 0657
(2018/04/26)
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- Chiral Titanium Coordination Assemblies: Robust Cooperative Self-Supported Catalysts for Asymmetric Ring Opening of meso-Epoxides with Aliphatic Amines
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By utilizing the oxygen bridge in dimeric μ-oxo-titanium-salen complexes as an efficient cross-linkage, a series of robust chiral titanium coordination assemblies has been successfully fabricated with the ditopic bridging ligands derived from BINOL and salen derivatives via coordination polymerization, which are fully characterized by IR, elemental analysis, XRD and microscopic studies. Because of their insolubility in most organic solvents and water, these metal-organic assemblies can successfully function as robust self-supported chiral catalysts, allowing an asymmetric ring opening (ARO) of meso-epoxides with aliphatic amines. Remarkably, owing to the linkage effects and the cooperation of two kinds of chiral titanium moieties in the metal-organic assemblies, the self-supported chiral catalysts demonstrate extremely high stability. They not only show high tolerance towards various meso-epoxides and nucleophilic aliphatic amines, but also can be reused in more than 20 runs without obvious metal leaching and loss in yields and enantioselectivities. Furthermore, the self-supported catalyst accomplished a one-pot tandem olefin epoxidation and ARO of an epoxide sequence starting from the olefin, 30% hydrogen peroxide and benzylamine. In marked contrast, the reaction failed to work when using the two corresponding homogeneous catalysts under identical reaction conditions. Good yields and enantioselectivities were obtained by the robust self-supported catalyst, which clearly indicates the cooperative effects between two chiral moieties within the metal-organic assemblies. The two catalytic centers can perform their own duties without interference and this further supports our strategy for the self-supported catalyst design. (Figure presented.).
- Sun, Zheming,Chen, Jiangbo,Liu, Yaoqi,Tu, Tao
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p. 494 - 505
(2017/02/10)
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- Fe(Cp)2BF4: An efficient lewis acid catalyst for the aminolysis of epoxides
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Ferrocenium tetrafluoroborate [Fe(Cp)2BF4] is an efficient Lewis acid catalyst for the aminolysis of aromatic, aliphatic, and cyclic epoxides using aniline and substituted anilines as the nucleophile to provide regioselective β-amino alcohols in 61-97% yields under solvent-free conditions at room temperature. The ring opening of cyclohexene oxide with aliphatic amines gave 2-aminocyclohexanols in 33-98% yields at 60 °C under solvent-free conditions. Georg Thieme Verlag Stuttgart New York.
- Yadav, Geeta Devi,Chauhan, Manmohan Singh,Singh, Surendra
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p. 629 - 634
(2014/03/21)
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- CYCLOHEXANEDIAMINE COMPOUNDS AND METHODS FOR THEIR PREPARATION
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The present invention provides processes for the preparation of cyclohexanediamine compounds of formula Ia and intermediates thereof. The compounds are useful as Syk kinase inhibitors and in various pharmaceutical compositions, and particularly useful for treating conditions mediated at least in part by Syk kinase activity.
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- An improved and efficient process for the scalable preparation of optically pure trans-2-aminocyclohexanols
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An improved and efficient process has been developed for a green and scalable preparation of optically pure (1R,2R) - and (1S,2S) -trans-2-aminocyclohexanols. The process utilised hot water to promote the aminolysis of cyclohexene oxide by benzylamine to afford racemic trans-2-(benzylamino)cyclohexanols, which were resolved by sequential and repeated use of (R)- and (S)-mandelic acid. Finally, after treatment of the two salts sequentially with HCl and NaOH and recovery of mandelic acid, liberation was achieved of the optically pure trans-2-benzylaminoaminocyclohexanols which were smoothly debenzylated using a low loading of a Pd/C catalyst to the trans-2-aminocyclohexanols. The synthetic route has been successfully applied to large-scale (1 mol) preparations in good yield.
- Xue, Feng,Li, Chang-Gong,Zhu, Yong,Lou, Tian-Jun
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p. 322 - 324
(2014/06/09)
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- Practical resolution of racemic trans-2-benzylaminocyclohexanol with di-p-toluoyl-l-tartaric acid via diastereomeric salt formation based on the Pope and Peachey method
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A new resolution process for racemic trans-2-benzylaminocyclohexanol 2, a key intermediate for chiral pharmaceuticals, was investigated. Di-p-toluoyl-l-tartaric acid 15 was found to be a new practical resolving agent in terms of stability and productivity of the resolution system. Resolution conditions were optimized based on the Pope and Peachey method, and the best result was obtained when HCl was added to the resolution system as a supplemental acid; 2/l-15/HCl = 1.0/0.6/0.4 (mol/mol/mol) (yield 92%, 99.5%de, E 92%).
- Ogawa, Ryuji,Fujino, Toshihiro,Hirayama, Noriaki,Sakai, Kenichi
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scheme or table
p. 2458 - 2461
(2009/04/11)
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- Efficient ring opening of aziridines with carboxylic acids
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An efficient ring cleavage of aziridines with acids has been studied in the absence of any catalyst. The hydrolysis of the products, amino esters, leads to the corresponding amino alcohols. The reaction has been extended to chiral cycloalkyl aziridines, leading to the formation of diastereomers. After separation, these diastereomers have been converted to optically pure amino alcohols in two steps. Copyright Taylor & Francis Group, LLC.
- Kumar, Manoj,Gandhi, Shikha,Kalra, Swinderjeet Singh,Singh, Vinod K.
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p. 1527 - 1532
(2008/09/20)
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- Resolution of racemic 2-aminocyclohexanol derivatives and their application as ligands in asymmetric catalysis
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A preparatively easy and efficient protocol for the resolution of racemic 2-aminocyclohexanol derivatives is described, delivering both enantiomers with >99% enantiomeric excess (ee) by sequential use of (R)- and (S)-mandelic acid. A simple aqueous workup procedure permits the isolation of the amino alcohols in analytically pure form and the almost quantitative recovery of mandelic acid. Debenzylation of enantiopure trans-2-(N-benzyl)amino-1- cyclohexanol by hydrogenation and subsequent derivatization give access to a broad variety of diversely substituted derivatives. Furthermore, the corresponding cis isomers are readily available. Applications of these optically active aminocyclohexanols in catalyzed asymmetric phenyl transfer reactions to benzaldehydes and transfer hydrogenations of aryl ketones lead to products with up to 96% ee.
- Schiffers, Ingo,Rantanen, Toni,Schmidt, Frank,Bergmans, Werner,Zani, Lorenzo,Bolm, Carsten
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p. 2320 - 2331
(2007/10/03)
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- Application of new chiral auxiliaries, trans-2-(N-arylsulfonyl-N-benzyl)cyclohexanols, in an asymmetric radical cyclization
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New chiral auxiliaries, trans-2-(N-arylsulfonyl-N-benzyl)cyclohexanols, were prepared and applied to an asymmetric radical cyclization. Copyright (C) 2000 Elsevier Science Ltd.
- Nishida, Atsushi,Shirato, Fumie,Nakagawa, Masako
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p. 3789 - 3805
(2007/10/03)
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