- Part III. COD versus NBD precatalysts. Dramatic difference in the asymmetric hydrogenation of prochiral olefins with five-membered diphosphine Rh-hydrogenation catalysts
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Induction periods in the asymmetric hydrogenation of prochiral olefins with five-membered chelates of the type [Rh(PP)(diolefin)]BF4 originate from the parallel-running hydrogenation of the prochiral substrate and the diolefin that enters the s
- Drexler, Hans-Joachim,Baumann, Wolfgang,Spannenberg, Anke,Fischer, Christine,Heller, Detlef
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Read Online
- Insights into Fast Amide Couplings in Aqueous Nanomicelles
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1-Ethyl-3-(3-(dimethylamino)propyl)-carbodiimide (EDC?HCl) has both lipophilic and hydrophilic regions, causing self-aggregation (also called nanoparticle formation) in an aqueous medium containing PS-750-M amphiphile. Kinetic and proton nuclear magnetic resonance studies were used to probe the effect of different organic bases on the potential nanoparticle formation of EDC?HCl. It also reveals why the pyridine base works better under micellar conditions. The methodology was examined on the multigram scale synthesis of bioactive molecules, where excellent reaction yields were obtained without product epimerization while maintaining a shorter reaction time.
- Sharma, Sudripet,Kaur, Gaganpreet,Handa, Sachin
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supporting information
p. 1960 - 1965
(2021/08/03)
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- Metal-Free Selective Modification of Secondary Amides: Application in Late-Stage Diversification of Peptides
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Here we solve a long-standing challenge of the site-selective modification of secondary amides and present a simple two-step, metal-free approach to selectively modify a particular secondary amide in molecules containing multiple primary and secondary amides. Density functional theory (DFT) provides insight into the activation of C-N bonds. This study encompasses distinct chemical advances for late-stage modification of peptides thus harnessing the amides for the incorporation of various functional groups into natural and synthetic molecules.
- Adebomi, Victor,Sriram, Mahesh,Streety, Xavier,Raj, Monika
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supporting information
p. 6189 - 6193
(2021/08/01)
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- Synthesis of Benzoisoselenazolones via Rh(III)-Catalyzed Direct Annulative Selenation by Using Elemental Selenium
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Isoselenazolone derivatives have attracted significant research interest because of their potent therapeutic activities and indispensable applications in organic synthesis. Efficient construction of functionalized isoselenazolone scaffolds is still challenging, and thus new synthetic approaches with improved operational simplicity have been of particular interest. In this manuscript, we introduce a rhodium-catalyzed direct selenium annulation by using stable and tractable elemental selenium. A series of benzamides as well as acrylamides were successfully coupled with selenium under mild reaction conditions, and the obtained isoselenazolones could be pivotal synthetic precursors for several organoselenium compounds. Based on the designed control experiments and X-ray absorption spectroscopy measurements, we propose an unprecedented selenation mechanism involving a highly electrophilic Se(IV) species as the reactive selenium donor. The reaction mechanism was further verified by a computational study.
- Xu-Xu, Qing-Feng,Nishii, Yuji,Uetake, Yuta,Sakurai, Hidehiro,Miura, Masahiro
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supporting information
p. 17952 - 17959
(2021/11/16)
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- Nickel-Catalyzed Asymmetric Hydrogenation of 2-Amidoacrylates
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Earth-abundant nickel, coordinated with a suitable chiral bisphosphine ligand, was found to be an efficient catalyst for the asymmetric hydrogenation of 2-amidoacrylates, affording the chiral α-amino acid esters in quantitative yields and excellent enantioselectivity (up to 96 % ee). The active catalyst component was studied by NMR and HRMS, which helped us to realize high catalytic efficiency on a gram scale with a low catalyst loading (S/C=2000). The hydrogenated products could be simply converted into chiral α-amino acids, β-amino alcohols, and their bioactive derivatives. Furthermore, the catalytic mechanism was investigated using deuterium-labeling experiments and computational calculations.
- Chen, Jianzhong,Gridnev, Ilya D.,Hu, Yawen,Li, Bowen,Zhang, Wanbin,Zhang, Zhenfeng
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supporting information
p. 5371 - 5375
(2020/02/15)
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- Rational Design of 2-Substituted DMAP- N-oxides as Acyl Transfer Catalysts: Dynamic Kinetic Resolution of Azlactones
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A novel concept that conversion of chiral 2-substituted DMAP into its DMAP-N-oxide could significantly enhance the catalytic activity and still be used as an acyl transfer catalyst is presented. A new type of chiral 2-substituted DMAP-N-oxides, derived from l-prolinamides, has been rationally designed, facilely synthesized, and applied in the dynamic kinetic resolution of azlactones. Using simple MeOH as the nucleophile, various l-amino acid derivatives were produced in high yields (up to 98% yield) and enantioselectivities (up to 96% ee). Furthermore, α-deuterium labeled l-phenylalanine derivative was also obtained. Experiments and DFT calculations revealed that in 2-substituted DMAP-N-oxide, the oxygen atom acted as the nucleophilic site and the N-H bond functioned as the H-bond donor. High enantioselectivity of the reaction was governed by steric factors, and the addition of benzoic acid reduced the activation energy by participating in the construction of a H-bond bridge. The theoretical chemical study indicated that only when attack directions of the chiral catalyst were fully considered could the correct calculation results be obtained. This work paves the way for the utilization of the C2 position of the pyridine ring and the development of chiral 2-substituted DMAP-N-oxides as efficient acyl transfer catalysts.
- Deng, Yun,Guo, Hai-Ming,Huang, Bin,Li, Ning,Qu, Gui-Rong,Tian, Yin,Wu, Xiao-Xia,Xie, Ming-Sheng
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supporting information
p. 19226 - 19238
(2020/11/13)
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- Fast Amide Couplings in Water: Extraction, Column Chromatography, and Crystallization Not Required
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In the micelle of PS-750-M, the presence of 3° amides from the surfactant proline linker mimics dimethylformamide, dimethylacetamide, and N-methyl-2-pyrrolidone. The resultant micellar properties enable extremely fast amide couplings mediated by 1-ethyl-3
- Sharma, Sudripet,Buchbinder, Nicklas W.,Braje, Wilfried M.,Handa, Sachin
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supporting information
p. 5737 - 5740
(2020/07/14)
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- An Efficient Catalytic Amidation of Esters Promoted by N-Heterocyclic Carbenes
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An efficient NHC-catalyzed amidation between esters and amines or hydrazines is described. This strategy was tolerant for a wide scope of substrates, affording a series of amides (or hydrazides) in good to excellent yields (60-96%) under simple conditions. The approach was also used to synthesize the pharmaceutically relevant antidepressant moclobemide in 85% yield.
- Chen, Ling-Yan,Wu, Mei-Fang
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p. 1595 - 1602
(2019/03/26)
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- Design, synthesis and evaluation of novel phenyl propionamide derivatives as non-nucleoside hepatitis B virus inhibitors
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As an ongoing search for potent non-nucleoside anti-HBV agents with novel structures, we described a series of phenyl propionamide derivatives (3a-b, 4a-e, 7a-g, 8a-h and 9a-b) by pharmacophore fusion strategy in the present work. All the compounds exhibited an anti-HBV activity to some extent. Among them, compounds 8d and 9b displayed most potent anti-HBV activity with IC50 values on HBV DNA replication of 0.46 and 0.14 μM, respectively. And the selective index values of 8d and 9b were more than 217.39 and 153.14, suggesting that 8d and 9b exhibited favorable safety profiles. Interestingly, 8d and 9b possessed significantly antiviral activities against lamivudine and entecavir resistant HBV mutants with IC50 values of 0.77 and 0.32 μM. Notably, preliminary anti-HBV action mechanism studies showed that 8d could inhibit intracellular HBV pgRNA and RT activity of the HBV polymerase. Molecular docking studies suggested that compound 8d could fit into the dimer-dimer interface of HBV core protein by hydrophobic interaction. In addition, in silico prediction of physicochemical properties showed that 8d conformed well to the Lipinski's rule of five, suggesting its potential for use as a drug like molecule. Taken together, 8d possessed significantly anti-HBV activity, low toxicity, diverse anti-HBV mechanism and favorable physicochemical properties, and warranted further investigation as a promising non-nucleoside anti-HBV candidate.
- Qiu, Jingying,Gong, Qineng,Gao, Jian,Chen, Wang,Zhang, Yinpeng,Gu, Xiaoke,Tang, Daoquan
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p. 424 - 434
(2018/01/01)
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- 1,1-Diacyloxy-1-phenylmethanes as versatile N-acylating agents for amines
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1,1-Diacyloxy-1-phenylmethanes and 1-pivaloxy-1-acyloxy-1-phenylmethanes have been used as bench stable N-acylating reagents for primary and secondary amines and anilines under solvent-free conditions to afford their corresponding amides in good yield.
- Chapman, Robert. S.L.,Tibbetts, Joshua. D.,Bull, Steven. D.
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p. 5330 - 5339
(2018/06/15)
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- Diboron-Catalyzed Dehydrative Amidation of Aromatic Carboxylic Acids with Amines
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Tetrakis(dimethylamido)diboron and tetrahydroxydiboron are herein reported as new catalysts for the synthesis of aryl amides by catalytic condensation of aromatic carboxylic acids with amines. The developed protocol is both simple and highly efficient over a broad range of substrates. This method thus represents an attractive approach for the use of diboron catalysts in the synthesis of amides without having to resort to stoichiometric or additional dehydrating agents.
- Sawant, Dinesh N.,Bagal, Dattatraya B.,Ogawa, Saeko,Selvam, Kaliyamoorthy,Saito, Susumu
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supporting information
p. 4397 - 4400
(2018/08/09)
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- Direct Amidation of Carboxylic Acids through an Active α-Acyl Enol Ester Intermediate
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The development of a highly efficient and simple protocol for the direct amidation of carboxylic acids is described employing ynoates as novel coupling reagents. The transformation proceeds in good to excellent yields via in situ α-acyl enol ester intermediates formation under mild reaction conditions. This useful method has been demonstrated for a range of substrates to provide a succinct access to structurally diverse amides, including key intermediates of glibenclamide, tiapride hydrochloride, and nateglinide, and can be conducted on a mole scale.
- Xu, Xianjun,Feng, Huangdi,Huang, Liliang,Liu, Xiaohui
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p. 7962 - 7969
(2018/06/18)
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- Design, synthesis, and molecular docking studies of N-(9,10-anthraquinone-2-carbonyl)amino acid derivatives as xanthine oxidase inhibitors
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A series of N-(9,10-anthraquinone-2-carbonyl)amino acid derivatives (1a–j) was designed and synthesized as novel xanthine oxidase inhibitors. Among them, the L/D-phenylalanine derivatives (1d and 1i) and the L/D-tryptophan derivatives (1e and 1j) were effective with micromolar level potency. In particular, the L-phenylalanine derivative 1d (IC50?=?3.0?μm) and the D-phenylalanine derivative 1i (IC50?=?2.9?μm) presented the highest potency and were both more potent than the positive control allopurinol (IC50?=?8.1?μm). Preliminary SAR analysis pointed that an aromatic amino acid fragment, for example, phenylalanine or tryptophan, was essential for the inhibition; the D-amino acid derivative presented equal or greater potency compared to its L-enantiomer; and the 9,10-anthraquinone moiety was welcome for the inhibition. Molecular simulations provided rational binding models for compounds 1d and 1i in the xanthine oxidase active pocket. As a result, compounds 1d and 1i could be promising lead compounds for further investigation.
- Zhang, Ting-Jian,Li, Song-Ye,Yuan, Wei-Yan,Zhang, Yi,Meng, Fan-Hao
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p. 893 - 901
(2018/03/21)
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- Synthesis and antimicrobial activities of novel sorbic and benzoic acid amide derivatives
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A series of sorbic and benzoic acid amide derivatives were synthesized by conjugating sorbic acid (SAAD, a1–a7) or benzoic acid (BAAD b1–b6) with amino acid esters and their antimicrobial activities were investigated against Escherichia coli, Bacillus subtilis and Staphylococcus aureus, mixed bacteria from rancid milk, Saccharomyces cerevisiae, and Aspergillus niger. The antimicrobial activity of sorbic acid amides was better than that of benzoic acid amides. The minimum inhibitory concentrations (MIC) of compound isopropyl N-[1-oxo-2, 4-hexadien-1-yl]-L-phenylalaninate (a7) were 0.17 mM against B. subtilis, and 0.50 mM against S. aureus, while the MIC values of sorbic acid were more than 2 mM respectively. Also, compound a7 displayed pH-independent antimicrobial activity in the range of pH 5.0–9.0 and was effective at pH 9.0. These results demonstrated that the conjugation of sorbic acid with amino acid esters led to significant improvement of in vitro antimicrobial attributes, but little effect was observed for benzoic acid amide derivatives.
- Wei, Qingyi,Wang, Xiaomei,Cheng, Jun-Hu,Zeng, Guangxiang,Sun, Da-Wen
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p. 220 - 232
(2018/06/26)
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- Dynamic Kinetic Resolution of Azlactones by a Chiral N, N-Dimethyl-4-aminopyridine Derivative Containing a 1,1′-Binaphthyl Unit: Importance of Amide Groups
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A dynamic kinetic resolution (DKR) of azlactones in the presence of benzoic acid and a binaphthyl-based N,N-4-dimethylaminopyridine (DMAP) derivative 1i having two amide groups at the 3,3′-positions of a binaphthyl unit is developed. The reaction proceeded smoothly with a wide range of azlactones to provide α-amino acid derivatives with good to high enantiomeric ratios (er's). A multigram-scale reaction (2.5 g) for the DKR of azlactone 2d was also demonstrated, and the resulting product was converted to unnatural α-amino acid 6d′.
- Mandai, Hiroki,Hongo, Kohei,Fujiwara, Takuma,Fujii, Kazuki,Mitsudo, Koichi,Suga, Seiji
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supporting information
p. 4811 - 4814
(2018/08/24)
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- Identification of 1,5,7-Triazabicyclododecene and Polystyrene-Supported Superbases as Efficient Hydroxylaminolysis Agents of Sterically Hindered and Epimerizable Esters
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In modern pharmaceutical research, the need for reliable protocols for the preparation of chemical libraries in a controlled manner is quintessential to driving the Design-Make-Test cycle in drug discovery programs. In this letter, we communicate the iden
- Pierre, Romain,Gaigne, Frédéric,El-Bazbouz, Ghizlane,Mouis, Grégoire,Ouvry, Gilles,Tomas, Loic,Harris, Craig S.
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supporting information
p. 1102 - 1106
(2018/04/24)
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- Oxidative amidation of benzyl alcohols with amino acid esters mediated by N-hydroxysuccinimide/phenyliodine diacetate
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A simple protocol involving metal-free oxidative amidation of benzyl alcohols with amino acid esters has been presented. The amidation proceeds in a radical pathway unlike in conventional metal-mediated extrusion of dihydrogen. The method is advantageous in terms of metal-free conditions, nonexpensive commercial starting substrates. Also various substituents in the starting materials are tolerated and sterically hindered amino acid side chains could provide good yields of amide products.
- Mahesh, Mandipogula,Panduranga, Veladi,Prabhu, Girish,Kumar L, Roopesh,Ramana, P. Venkata,Sureshbabu, Vommina V.
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p. 716 - 721
(2017/03/27)
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- Novel L-arginine derivatives as aminopeptidase N inhibitors: design, chemistry, and pharmacological evaluation
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Considering the important roles played in tumor, aminopeptidase N has been an appealing target for anti-tumor drug development. Here, a serial of novel aminopeptidase N inhibitors with L-arginine scaffold were designed, synthesized and evaluated for aminopeptidase N inhibitory activities. The preliminary anti-enzyme activity assay demonstrated that compounds 5e, 5h, 11e, 11g, and 11h showed comparable activities with the positive control bestatin, an approved aminopeptidase N inhibitor. In vitro anti-proliferation assay, compound 5f showed excellent activities against four kinds of tumor cells which overexpress aminopeptidase N. In vivo anti-metastasis assay, compounds 5f and 11g exhibited better activities than bestatin. So 5f and 11g should be lead compounds as novel aminopeptidase N inhibitors for further development.
- Mou, Jiajia,Luan, Yepeng,Chen, Danghui,Wang, Qiang
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p. 3015 - 3025
(2017/10/06)
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- MgI2-chemoselective cleavage for removal of amino acid protecting groups: A fresh vision for peptide synthesis
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In the field of peptide synthesis, the key to a successful access to synthetic targets lies on a pertinent combination of protecting groups. Their choice is directed by their selective removal conditions. We present here the behavior of some of the most used protecting groups in peptide chemistry under experimental cleavage conditions, combining MgI2 with MW irradiation, using 2-Me-THF as a green solvent. In these experimental conditions, the benzyloxycarbonyl protecting group as well as the Merrifield resin can be re-considered in peptide chemistry.
- Berthet, Mathéo,Martinez, Jean,Parrot, Isabelle
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- Design, synthesis and docking studies of novel dipeptidyl boronic acid proteasome inhibitors constructed from αα- and αβ-amino acids
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A series of novel dipeptidyl boronic acid proteasome inhibitors constructed from αα- and αβ-amino acids were designed and synthesized. Their structures were elucidated by 1H NMR, 13C NMR, LC-MS and HRMS. These compounds were evaluated for their β5 subunit inhibitory activities of human proteasome. The results showed that dipeptidyl boronic acid inhibitors composed of αα-amino acids were as active as bortezomib. Interestingly, the activities of those derived from αβ-amino acids lost completely. Of all the inhibitors, compound 22 (IC50 = 4.82 nM) was the most potent for the inhibition of proteasome activity. Compound 22 was also the most active against three MM cell lines with IC50 values less than 5 nM in inhibiting cell growth assays. Molecular docking studies displayed that 22 fitted very well in the β5 subunit active pocket of proteasome.
- Shi, Jingmiao,Lei, Meng,Wu, Wenkui,Feng, Huayun,Wang, Jia,Chen, Shanshan,Zhu, Yongqiang,Hu, Shihe,Liu, Zhaogang,Jiang, Cheng
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supporting information
p. 1958 - 1962
(2016/04/05)
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- A new type of chiral-pyridoxamines for catalytic asymmetric transamination of α-keto acids
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A new type of chiral pyridoxamines bearing an adjacent chiral stereocenter has been developed via multi-step synthesis. The pyridoxamines displayed catalytic activity in asymmetric transamination of α-keto acids to give a variety of optically active amino acids in 27–78% yields with 34–62% ee's under very mild conditions. This work provides a synthetic strategy to construct new chiral pyridoxamines using bromopyridine 7 as a key synthon and also represents an early example of the applications of chiral pyridoxamines in asymmetric catalysis.
- Chen, Jianfeng,Zhao, Junyu,Gong, Xing,Xu, Dongfang,Zhao, Baoguo
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supporting information
p. 4612 - 4615
(2016/09/23)
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- A facile and rapid preparation of hydroxamic acids by hydroxylaminolysis using DBU as base
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While there are many protocols for the preparation of hydroxamic acids from their corresponding carboxylic acid or carboxylic ester precursors, most use strong mineral bases that can lead to carboxylic acid impurities that can be difficult to remove using standard chromatographic techniques. This problem is exacerbated when the carbonyl group is hindered. Herein, we communicate a robust hydroxylaminolysis protocol for the preparation of hydroxamic acids in high yield and purity.
- Beillard, Audrey,Bhurruth-Alcor, Yushma,Bouix-Peter, Claire,Bouquet, Karinne,Chambon, Sandrine,Clary, Laurence,Harris, Craig S.,Millois, Corinne,Mouis, Grégoire,Ouvry, Gilles,Pierre, Romain,Reitz, Arnaud,Tomas, Loic
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supporting information
p. 2165 - 2170
(2016/05/02)
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- Highly efficient dehydrogenative cross-coupling of aldehydes with amines and alcohols
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A common protocol for the synthesis of amides, esters and α-ketoesters via cross dehydrogenative coupling of aldehydes and amines/alcohols has been developed. The method is applicable to a wide variety of alcohols and amines as well as aliphatic and aromatic aldehydes. Also, the use of acetaldehyde for acetylation and ethyl glyoxalate to access 2-oxo-amino esters is presented for the first time.
- Deshidi, Ramesh,Rizvi, Masood Ahmad,Shah, Bhahwal Ali
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p. 90521 - 90524
(2015/11/11)
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- Peptide-catalyzed conversion of racemic oxazol-5(4 H)-ones into enantiomerically enriched α-amino acid derivatives
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We report the development and optimization of a tetrapeptide that catalyzes the methanolytic dynamic kinetic resolution of oxazol-5(4H)-ones (azlactones) with high levels of enantioinduction. Oxazolones possessing benzylic-type substituents were found to perform better than others, providing methyl ester products in 88:12 to 98:2 er. The mechanism of this peptide-catalyzed process was investigated through truncation studies and competition experiments. High-field NOESY analysis was performed to elucidate the solution-phase structure of the peptide, and we present a plausible model for catalysis.
- Metrano, Anthony J.,Miller, Scott J.
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p. 1542 - 1554
(2014/03/21)
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- A convenient and efficient synthesis of dipeptidyl benzoxaboroles and their peptidomimetics
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We have developed a convenient and efficient method for the synthesis of dipeptidyl benzoxaboroles and their peptidomimetics. The novel dipeptidyl benzoxaboroles were obtained by the protecting-group-free coupling of 6-amino-1,3-dihydro-2,1-benzoxaborol-1-ol with various N-(arylcarbonyl) phenylalanines. Bioisosteric replacement of the terminal amide moiety of dipeptidyl benzoxaboroles by 1,3,4-oxadiazoles or 4H-3,1-benzothiazin-4-one provided their peptidomimetics with good molecular diversity. These transformations were based on the pluripotency of methyl (S)-2-isothiocyanato-3- phenylpropanoate and were highlighted by mild reaction conditions, high atom efficiency, and good to excellent isolated yields. This method is a valuable addition to the development of novel drug-like boronic acid molecules. Georg Thieme Verlag Stuttgart ? New York.
- Fu, Zhengyan,He, Jiangpeng,Tong, Aiping,Xie, Yongmei,Wei, Yuquan
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supporting information
p. 2843 - 2852
(2013/10/22)
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- Bis(4,6-dimethoxy-1,3,5-triazin-2-yl) ether as coupling reagent for peptide synthesis
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Bis(4,6-dimethoxy-1,3,5-triazin-2-yl) ether (4) was prepared by treatment of 2-hydroxy-4,6-dimethoxy-1,3,5-triazine with 2-chloro-4,6-dimethoxy-1,3,5- triazine in 61% yield. Ether 4, isoelectronic with pyrocarbonates, was found capable to activate carboxylic acids in the presence of 1,4-diazabicyclo[2.2.2] octane (DABCO) to yield, under mild reaction conditions, superactive triazine esters. Versatility of this new coupling reagent was confirmed by condensation of lipophilic and sterically hindered carboxylic acids with amines in 71-98% yield, and by synthesis of peptides, including those containing Aib-Aib sequence, in solution with high yield and high enantiomeric purity. Copyright
- Jastrzabek, Konrad,Bednarek, Przemyslaw,Kolesinska, Beata,Kaminski, Zbigniew J.
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p. 952 - 961
(2013/07/28)
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- Iodide-catalyzed amide synthesis from alcohols and amines
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An efficient method to prepare amides by a cascade strategy was developed. Using nBu4NI or NaI as the catalyst and tert-butyl hydroperoxide as the oxidant, various alcohols reacted with N-hydroxysuccinimide or N-hydroxyphthalimide affording corresponding active esters in moderate to good yield. The resulting active esters were converted into amides smoothly in one pot. The Royal Society of Chemistry 2013.
- Wang, Gao,Yu, Qing-Ying,Wang, Jian,Wang, Shan,Chen, Shan-Yong,Yu, Xiao-Qi
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p. 21306 - 21310
(2013/11/06)
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- Tandem oxidative amidation of benzyl alcohols with amine hydrochloride salts catalysed by iron nitrate
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A tandem process for the oxidative amidation of benzyl alcohols with amine hydrochloride salts has been developed using inexpensive Fe(NO3) 3 as the catalyst, air and aqueous t-butyl hydroperoxide as oxidants. A wide range of benzamides have been synthesized under mild conditions. This greener amide formation method provides an economical and practical assess to benzamides from readily available and inexpensive starting materials.
- Ghosh, Subhash Chandra,Ngiam, Joyce S.Y.,Seayad, Abdul M.,Tuan, Dang Thanh,Johannes, Charles W.,Chen, Anqi
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p. 4922 - 4925
(2013/09/02)
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- Copper-catalyzed oxidative amidation of aldehydes with amine salts: Synthesis of primary, secondary, and tertiary amides
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A practical method for the amidation of aldehydes with economic ammonium chloride or amine hydrochloride salts has been developed for the synthesis of a wide variety of amides by using inexpensive copper sulfate or copper(I) oxide as a catalyst and aqueous tert-butyl hydroperoxide as an oxidant. This amidation reaction is operationally straightforward and provides primary, secondary, and tertiary amides in good to excellent yields for most cases utilizing inexpensive and readily available reagents under mild conditions. In situ formation of amine salts from free amines extends the substrate scope of the reaction. Chiral amides are also synthesized from their corresponding chiral amines without detectable racemization. The practicality of this amide formation reaction has been demonstrated in an efficient synthesis of the antiarrhythmic drug N-acetylprocainamide.
- Ghosh, Subhash Chandra,Ngiam, Joyce S. Y.,Seayad, Abdul M.,Tuan, Dang Thanh,Chai, Christina L. L.,Chen, Anqi
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p. 8007 - 8015,9
(2012/12/12)
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- Copper-catalyzed oxidative amidation of aldehydes with amine salts: Synthesis of primary, secondary, and tertiary amides
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A practical method for the amidation of aldehydes with economic ammonium chloride or amine hydrochloride salts has been developed for the synthesis of a wide variety of amides by using inexpensive copper sulfate or copper(I) oxide as a catalyst and aqueous tert-butyl hydroperoxide as an oxidant. This amidation reaction is operationally straightforward and provides primary, secondary, and tertiary amides in good to excellent yields for most cases utilizing inexpensive and readily available reagents under mild conditions. In situ formation of amine salts from free amines extends the substrate scope of the reaction. Chiral amides are also synthesized from their corresponding chiral amines without detectable racemization. The practicality of this amide formation reaction has been demonstrated in an efficient synthesis of the antiarrhythmic drug N-acetylprocainamide.
- Ghosh, Subhash Chandra,Ngiam, Joyce S.Y.,Seayad, Abdul M.,Tuan, Dang Thanh,Chai, Christina L.L.,Chen, Anqi
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p. 8007 - 8015
(2013/01/15)
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- Synthesis and biological evaluation of Matijing-Su derivatives as potent anti-HBV agents
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A series of Matijing-Su (MTS, N-(N-benzoyl-l-phenylalanyl)-O-acetyl-l- phenylalanol) derivatives were synthesized and evaluated for their anti-hepatitis B virus (HBV) activity in 2.2.15 cells. The IC50 of compounds 14a (0.71 μM), 13c (2.85 μM), 13b (4.37 μM), etc. and the selective index of 13g (161.01), 13c (90.45), 13a (85.09) etc. of the inhibition on the replication of HBV DNA were better than those of the positive control lamivudine (IC50: 82.42 μM, SI: 41.59). Compounds 13o, 13p, and 16a also exhibited significant anti-HBV activity.
- Qiu, Jingying,Xu, Bixue,Huang, Zhengming,Pan, Weidong,Cao, Peixue,Liu, Changxiao,Hao, Xiaojiang,Song, Baoan,Liang, Guangyi
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experimental part
p. 5352 - 5360
(2011/10/12)
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- Facile amide formation via S -nitrosothioacids
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Here we report a novel amide bond formation strategy from simple thioacid and amine starting materials. The reaction is mediated by unstable but very reactive S-nitrosothioacid intermediates. This fast reaction under mild conditions should be useful in synthesis.(Figure Presented)
- Pan, Jia,Devarie-Baez, Nelmi O.,Xian, Ming
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supporting information; experimental part
p. 1092 - 1094
(2011/04/25)
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- Design, synthesis and primary activity assay of bi- or tri-peptide analogues with the scaffold l-arginine as amino-peptidase N/CD13 inhibitors
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A series of bi- or tri-peptide analogues with the scaffold l-arginine were designed, synthesized and evaluated for their inhibitory activities against amino-peptidase N (APN) and metalloproteinase-2 (MMP-2). The primary activity assay showed that all the compounds exhibited higher inhibitory activities against APN than MMP-2. Within this series, compounds C6 and C7 (IC50 = 4.2 and 4.3 μM) showed comparable APN inhibitory activities with the positive control bestatin (IC50 = 3.8 μM).
- Mou, Jiajia,Fang, Hao,Liu, Yingzi,Shang, Luqing,Wang, Qiang,Zhang, Lei,Xu, Wenfang
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scheme or table
p. 887 - 895
(2010/05/02)
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- Electron-donating and rigid p-stereogenic bisphospholane ligands for highly enantioselective rhodium-catalyzed asymmetric hydrogenations
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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)
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- Tricyclononene carboxamide derivatives as novel anti-HIV-1 agents
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By modifying the chemical structure of anti-orthopoxvirus compound ST-246, we designed and synthesized a series of tricyclononene carboxamide derivatives and tested their anti-HIV-1 activity and cytotoxicity. We found that benzoimidazol-containing compound 7g was highly effective in inhibiting HIV-1 R5 infection with an IC50 value of 0.41 μM and a selectivity index of 292, but it exhibited no significant inhibitory activity on HIV-1 reverse transcriptase, integrase and protease. CoMFA was used to analyze structure-activity relationships with good predictive power (r2 = 0.921; q2 = 0.582). Moreover, the CoMFA model showed that the length of the molecule, the amide, and the amine moieties all played crucial roles in anti-HIV activity. These results suggest that 7g may serve as a lead for the development of novel anti-HIV-1 therapies. A series of tricyclononene carboxamide derivatives based on anti-orthopoxvirus compound ST-246 were synthesized and characterized as novel anti-HIV-1 agents.
- Dong, Ming-Xin,Zhang, Jian,Peng, Xu-Qing,Lu, Hong,Yun, Liu-Hong,Jiang, Shibo,Dai, Qiu-Yun
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scheme or table
p. 4096 - 4103
(2010/10/02)
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- Angiotensin I-converting enzyme (ace) inhibitors
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This invention relates to a process for the synthesis of ketomethylene derivatives of the tripeptide Phe-Gly-Pro (“keto-ACE”, compound 5a) and analogues thereof. The synthesis process proceeds via an α,β-unsaturated keto intermediate. A key feature of the process involves a Horner-Emmons olefination of the, -unsaturated keto-phosphonate with ethyl glyoxylate. Keto-ACE analogues produced by the process of the invention display C-domain selectivity.
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Page/Page column 4-5
(2009/12/04)
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- Copper + nickel-in-charcoal (Cu-Ni/C): A bimetallic, heterogeneous catalyst for cross-couplings
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(Chemical Equation Presented) A new heterogeneous catalyst composed of copper and nickel oxide particles supported within charcoal has been developed. It catalyzes cross-couplings that traditionally use palladium, nickel, or copper, including Suzuki-Miyaura reactions, Buchwald-Hartwig aminations, vinylalane alkylations, etherifications of aryl halides, aryl halide reductions, asymmetric conjugate reductions of activated olefins, and azide-alkyne "click" reactions.
- Lipshutz, Bruce H.,Nihan, Danielle M.,Vinogradova, Ekaterina,Taft, Benjamin R.,Boskovic, Zarko V.
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supporting information; experimental part
p. 4279 - 4282
(2009/05/30)
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- New pseudonucleosides containing chiral oxazolidin-2-ones and Cyclosulfamides as aglycones: Synthesis and antiviral evaluation
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A series of chiral cyclosulfamides and oxazolidinon-2-ones have been synthesized starting from aminoacids. Regioselective substitution of these pseudopyrimidic heterocyles was carried out under Mitsunobu conditions. Best substitution results were obtained by preliminary deprotection of cyclosulfamides and their condensation with β -D-ribofuranose. Chiral oxazolidin-2-ones were coupled directly with D-ribofuranose. All compounds were tested against HSV-2, VV and SV viruses. Two compounds 6b and 6e showed significant activities against HSV-type 1. Copyright Taylor & Francis Group, LLC.
- Bouleghlem, Hocine,Berredjem, Malika,Lecouvey, Marc,Aouf, Nour-Eddine
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p. 1539 - 1542
(2008/09/20)
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- New boron(III)-catalyzed amide and ester condensation reactions
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In 1996, we reported that benzeneboronic acids bearing electron-withdrawing groups at the meta- or para-position are highly effective catalysts for the amide condensation reaction in less-polar solvents. In this paper, we report that N-alkyl-4-boronopyridinium halides are more effective catalysts than the previous ones in more polar solvents. N-Alkyl-4-boronopyridinium halides are effective not only for amide condensation between equimolar mixtures of carboxylic acids and amines but also for the esterification of α-hydroxycarboxylic acids in alcohol solvents. Furthermore, perchlorocatecholborane is more effective than areneboronic acids for the amide condensation of sterically demanding carboxylic acids. In addition, Lewis acid-assisted Br?nsted acid (LBA), which is prepared from a 1:2 M mixture of boric acid and tetrachlorocatechol, is effective for the Ritter reaction from alcohols and nitriles to amides.
- Maki, Toshikatsu,Ishihara, Kazuaki,Yamamoto, Hisashi
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p. 8645 - 8657
(2008/02/08)
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- Asymmetric hydrogenation of methyl α-benzamido cinnamate in ionic liquid solvent
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The room temperature ionic liquid EMIMOTf was employed as the sole reaction solvent for the asymmetric hydrogenation of methyl α-benzamido cinnamate. Under conditions of 60 psi hydrogen and 50°C for 24 h, near quantitative conversions were observed using
- Boyle, Katherine L.,Lipsky, Emily Beth,Kalberg, Christopher S.
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p. 1311 - 1313
(2007/10/03)
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- Synthesis of a novel spiro bisphosphinite ligand and its application in Rh-catalyzed asymmetric hydrogenation
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A novel, chiral bisphosphinite ligand (R)-SpiroBIP has been synthesized. The rhodium complex of the ligand was found to be highly enantioselective in the asymmetric hydrogenation of α-dehydroamino acid derivatives.
- Guo, Zhenqiu,Guan, Xiaoyu,Chen, Zhiyong
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p. 468 - 473
(2007/10/03)
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- Synthesis of novel keto-ACE analogues as domain-selective angiotensin I-converting enzyme inhibitors
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Novel analogues of the angiotensin I-converting enzyme (ACE) inhibitor keto-ACE were synthesized via a facile Horner-Emmons olefination of a phosphonoketone precursor with ethyl glyoxylate. Introduction of a bulky aromatic tryptophan at the P2
- Nchinda, Aloysius T.,Chibale, Kelly,Redelinghuys, Pierre,Sturrock, Edward D.
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p. 4612 - 4615
(2007/10/03)
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- Synthesis and application of phosphinoferrocenylaminophosphine ligands for asymmetric catalysis
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(Chemical Equation Presented) A new class of bidentate ligands utilizing a phosphine-aminophosphine structure has been prepared on a ferrocenylethyl backbone in a straightforward and scalable fashion from acetylferrocene. The unique property of the α-ferrocenyl carbonium ion that allows the replacement of a variety of "leaving groups" with retention of configuration greatly facilitates the synthesis, and a number of ligands have been prepared by varying the nitrogen and phosphorus substituents on the aminophosphine. These readily prepared phosphinoferrocenylaminophosphines, known as BoPhoz ligands, show surprising hydrolytic and air stability, with no degradation after 3 years open to the air. The rhodium complexes of these ligands show exceedingly high enantioselectivities (generally > 95% ee) and activities often in excess of 50 000 catalyst turnovers per hour for the asymmetric hydrogenation of a wide variety of dehydro-α-amino acid and itaconic acid derivatives. They also show high activity and good to excellent enantioselectivity for the hydrogenation of a number of α-ketoesters.
- Boaz, Neil W.,Mackenzie, Elaine B.,Debenham, Sheryl D.,Large, Shannon E.,Ponasik Jr., James A.
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p. 1872 - 1880
(2007/10/03)
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- Novel phosphine-phosphite and phosphine-phosphinite ligands for highly enantioselective asymmetric hydrogenation
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Two novel phosphine-phosphite (S,R)-o-BINAPHOS and phosphine-phosphinite (S)-o-BIPNITE ligands based on ortho phenyl substituted (S)-BINOL have been synthesized. Extremely high enantioselectivity (over 99% ee in most cases) has been achieved for the Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acid derivatives.
- Yan, Yongjun,Chi, Yongxiang,Zhang, Xumu
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p. 2173 - 2175
(2007/10/03)
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- Synthesis of ortho-phenyl substituted MeO-BIPHEP ligand and its application in Rh-catalyzed asymmetric hydrogenation
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A new BIPHEP-type ligand with phenyl groups at the 3,3′-positions, o-Ph-MeO-BIPHEP 3 was prepared. This ligand afforded excellent enantioselectivities when used in the Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acid derivatives. The strong influence of o-phenyl groups of the ligand on the enantioselectivities of the reaction has been demonstrated by a comparison with its parent ligand MeO-BIPHEP.
- Wu, Shulin,He, Minsheng,Zhang, Xumu
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p. 2177 - 2180
(2007/10/03)
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- Asymmetric catalysis based on chiral phospholanes and hydroxyl phospholanes
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Chiral phosphine ligands derived from chiral natural products including D-mannitol and tartaric acid. The ligands contain one or more 5-membered phospholane rings with multiple chiral centers, and provide high stereoselectivity in asymmetric reactions.
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Page column 22
(2010/02/06)
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- Simple and Efficient Cleavage Reaction of the Boc Group in Heterocyclic Compounds
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A series of chiral cyclosulfamides have been synthesized by alkaline cyclisation starting from N-benzoylamino acids (Ala, Val, Leu, Phe) derivatives and chlorosulfonyl isocyanate. A simplified and regioselective deprotection of the cyclic compounds (cyclosulfamides) containing the tert-butyloxycarbonyl group (Boc) has been achieved in good yield by fusion under reduced pressure.
- Nadia, Klai,Malika, Berredjem,Nawel, Khettache,MedYazid, Belghit,Zine, Regainia,Aouf, Nour-Eddine
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- Application of chiral mixed phosphorus/sulfur ligands to enantioselective rhodium-catalyzed dehydroamino acid hydrogenation and ketone hydrosilylation processes
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Chiral mixed phosphorus/sulfur ligands 1-3 have been shown to be effective in enantioselective Rh-catalyzed dehydroamino acid hydrogenation and ketone hydrosilylation reactions (eqs 1, 2). After assaying the influence of the substituents at sulfur, the substituents on the ligand backbone, the relative stereochemistry within the ligand backbone, and the substituents at phosphorus, ligands 2c (R = 3,5-dimethylphenyl) and 3 were found to be optimal in the Rh-catalyzed hydrogenation of a variety of α-acylaminoacrylates in high enantioselectivity (89-97% ee). A similar optimization of the catalyst for the Rh-catalyzed hydrosilylation of ketones showed that ligand 3 afforded the highest enantioselectivities for a wide variety of aryl alkyl and dialkyl ketones (up to 99% ee). A model for asymmetric induction in the hydrogenation reaction is discussed in the context of existing models, based on the absolute stereochemistry of the products and the X-ray crystal structures of catalyst precursors and intermediates.
- Evans, David A.,Michael, Forrest E.,Tedrow, Jason S.,Campos, Kevin R.
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p. 3534 - 3543
(2007/10/03)
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- H8-MonoPhos and its application in catalytic enantioselective hydrogenation of α-dehydroamino acids
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H8-MonoPhos, a new stable and readily soluble monodentate phosphoramidite ligand, has been facilely prepared from H8-BINOL. The ligand achieved up to 99.9% ee and 96.7% ee in hydrogenation of dehydroalanine and dehydrohomophenylalani
- Zeng, Qingle,Liu, Hui,Mi, Aiqiao,Jiang, Yaozhong,Li, Xingshu,Choi, Michael C.K,Chan, Albert S.C
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p. 8799 - 8803
(2007/10/03)
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- Development of Nickel-on-Charcoal as a Dirt-Cheap Heterogeneous Catalyst: A Personal Account
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A personal account tracing the origins and continuing evolution of nickel-on-charcoal (Ni/C) as a practical, alternative, group 10 metal catalyst is presented. Discussed are applications to several name reactions which lead to both carbon-carbon and carbon-nitrogen bond constructions utilizing inexpensive aryl chlorides as substrates. Reductions of chloroarenes are also catalyzed by Ni/C, a process which may be worthy of consideration in terms of environmental cleanup of PCBs and dioxins. Collaborative efforts are also mentioned aimed at probing the surface structure of Ni/C, with the goal of enhancing catalyst activity. Future directions for development of heterogeneous nickel catalysts are proposed.
- Lipshutz, Bruce H.
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p. 313 - 326
(2007/10/03)
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