- Synthesis of (1H-1,2,3-Triazol-1-yl)acetic Acid Derivatives
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Abstract: A convenient synthetic approach to (1H-1,2,3-triazol-1-yl)acetic acid derivatives via the reaction of azidoacetamides with β-ketoesters and acetylacetone is proposed. Based on this strategy, 1,5-disubstituted 1,2,3-triazoles were prepared from available reagents under metal-free conditions. A one-pot protocol for the synthesis of (5-methyl-1H-1,2,3-triazol-1-yl)acetamides derived from N-substituted chloroacetamides is developed.
- Obushak, M. D.,Pokhodylo, N. T.,Savka, R. D.
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p. 1421 - 1431
(2020/10/02)
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- N-Hydroxybenzimidazole as a structurally modifiable platform forN-oxyl radicals for direct C-H functionalization reactions
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Methods for direct functionalization of C-H bonds mediated byN-oxyl radicals constitute a powerful tool in modern organic synthesis. While severalN-oxyl radicals have been developed to date, the lack of structural diversity for these species has hampered further progress in this field. Here we designed a novel class ofN-oxyl radicals based onN-hydroxybenzimidazole, and applied them to the direct C-H functionalization reactions. The flexibly modifiable features of these structures enabled facile tuning of their catalytic performance. Moreover, with these organoradicals, we have developed a metal-free approach for the synthesis of acyl fluoridesviadirect C-H fluorination of aldehydes under mild conditions.
- Hatanaka, Miho,Jiang, Julong,Maruoka, Keiji,Matsumoto, Akira,Sakamoto, Ryu,Sakurai, Shunya,Tsuzuki, Saori,Yoshii, Tomomi
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p. 5772 - 5778
(2020/06/22)
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- Chiral Vanadyl(V) Complexes Enable Efficient Asymmetric Reduction of β-Ketoamides: Application toward (S)-Duloxetine
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High-valent chiral oxidovanadium(V) complexes derived from 3,5-substituted-N-salicylidene-l-tert-leucine were used as catalysts in asymmetric reduction of N-benzyl-β-ketoamides. Among six different solvents, three different alcohol additives, and two different boranes examined, the use of pinacolborane in tetrahydrofuran (THF) with a t-BuOH additive led to the best results at -20 °C. The corresponding β-hydroxyamides can be furnished with yields up to 92percent and an enantiomeric excess (ee) up to 99percent. We have successfully extended this catalytic protocol for the synthesis of an (S)-duloxetine precursor.
- Chen, Chien-Tien,Maity, Nabin Ch.,Agarwal, Rachit,Lai, Chien-Fu,Liao, Yiya,Yu, Wei-Ru
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supporting information
p. 6408 - 6419
(2020/07/14)
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- Chiral Surfactant-Type Catalyst: Enantioselective Reduction of Long-Chain Aliphatic Ketoesters in Water
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A series of amphiphilic ligands were designed and synthesized. The rhodium complexes with the ligands were applied to the asymmetric transfer hydrogenation of broad range of long-chained aliphatic ketoesters in neat water. Quantitative conversion and excellent enantioselectivity (up to 99% ee) was observed for α-, β-, γ-, δ- and ε-ketoesters as well as for α- and β-acyloxyketone using chiral surfactant-type catalyst 2. The CH/π interaction and the strong hydrophobic interaction of long aliphatic chains between the catalyst and the substrate in the metallomicelle core played a key role in the catalytic transition state. Synergistic effects between the metal-catalyzed site and the hydrophobic microenvironment of the core in the micelle contributed to high stereoselectivity. (Chemical Equation Presented).
- Lin, Zechao,Li, Jiahong,Huang, Qingfei,Huang, Qiuya,Wang, Qiwei,Tang, Lei,Gong, Deying,Yang, Jun,Zhu, Jin,Deng, Jingen
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p. 4419 - 4429
(2015/05/13)
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- Mechanistic studies on the CAN-mediated intramolecular cyclization of δ-aryl-β-dicarbonyl compounds
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The synthesis of 2-tetralones through the cyclization of δ-aryl-β-dicarbonyl substrates by using CAN is described. Appropriately functionalized aromatic substrates undergo intramolecular cyclizations generating 2-tetralone derivatives in moderate to good yields. DFT computational studies indicate that successful formation of 2-tetralones from δ-aryl-β-dicarbonyl radicals is dependent on the stability of the subsequent cyclohexadienyl radical intermediates. Furthermore, DFT computational studies were used to rationalize the observed site selectivity in the 2-tetralone products.
- Casey, Brian M.,Sadasivam, Dhandapani V.,Flowers II, Robert A.
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p. 1472 - 1479
(2013/08/23)
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- CHEMICAL COMPOUNDS
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The invention is directed to to substituted indazole derivatives. Specifically, the invention is directed to compounds according to Formula I: wherein R1 - R6 and X are defined herein. The compounds of the invention are inhibitors of PDK1 and can be useful in the treatment of disorders characterized by constitutively activated ACG kinases such as cancer and more specifically leukemia and cancers of the breast, colon, and lung. Accordingly, the invention is further directed to pharmaceutical compositions comprising a compound of the invention. The invention is still further directed to methods of inhibiting PDK1 activity and treatment of disorders associated therewith using a compound of the invention or a pharmaceutical composition comprising a compound of the invention.
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Page/Page column 136
(2010/11/04)
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- Mild conversion of β-diketones and β-ketoesters to carboxylic acids
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A mild protocol for the conversion of β-ketoesters and β-diketones to carboxylic acids with use of CAN in CH3CN is described. The method is compatible with a number of functional groups, and can generate carboxylic acids under neutral conditions at room temperature. The reaction is fast and general, providing an alternative method to the commonly used malonic ester acid preparation. Initial mechanistic studies show that initial oxidation of the enol form of the β-dicarbonyl initiates the reaction. The presence of nitrate as an oxidant ligand or as an additive is critical for success of the reaction.
- Zhang, Yang,Jiao, Jingliang,Flowers II, Robert A.
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p. 4516 - 4520
(2007/10/03)
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- Chemoenzymatic synthesis of enantiomerically enriched kavalactones
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Lipase-mediated kinetic resolution of methyl-3-hydroxy-5-phenylpentanoate and (6E)-ethyl 5-hydroxy-3-oxo-7-phenylhept-6-enoate is described in high enantiomeric excess and good yields. The effect of different lipases in different solvents has been screened using different acylating agents. This protocol has been extended for the preparation of enantiomerically pure biologically important kavalactones.
- Kamal, Ahmed,Krishnaji, Tadiparthi,Khanna, G.B. Ramesh
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p. 8657 - 8660
(2007/10/03)
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- Enantioselective synthesis of α-amino acids from N-tosyloxy β-lactams derived from β-keto esters
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A novel synthetic sequence has been developed to convert simple β-keto esters into enantiomerically enriched α-amino acids. The key features of this sequence include the addition of azide to the C3 position of β-keto ester derived N-tosyloxy-β-lactams through a concomitant nucleophilic addition/N-O bond reduction reaction, a mild CsF-induced N1 benzylation of α-azido monocyclic β-lactams, the preparation of α-keto-β-lactams through a novel four-step sequence from the corresponding 3-azido-1-benzyl-β-lactams, and TEMPO-mediated ring expansion of these compounds to the corresponding N-carboxy anhydrides (NCAs). In addition, the synthesis, isolation, and characterization of unusual 3-imino and 3-chloramino-β-lactams is reported.
- Durham, Timothy B.,Miller, Marvin J.
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- Method for preparing chiral diphosphines
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The invention concerns a method for preparing a compound of formula (1) wherein: A represents naphthyl or phenyl optionally substituted; and Ar1, Ar2independently represent a saturated or aromatic carbocyclic group, optionally substituted.
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- Asymmetric hydrogenation method of a ketonic compound and derivative
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The present invention relates to a process for the asymmetric hydrogenation of a ketonic compound and derivative. The invention relates to the use of optically active metal complexes as catalysts for the asymmetric hydrogenation of a ketonic compound and derivative. The process for the asymmetric hydrogenation of a ketonic compound and derivative is characterized in that the asymmetric hydrogenation of said compound is carried out in the presence of an effective amount of a metal complex comprising as ligand an optically active diphosphine corresponding to one of the following formulae: STR1
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- Enantioselective synthesis of (+)- and (-)-dihydrokawain
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The first asymmetric synthesis of (+)- and (-)-dihydrokawain, an α-dihydropyrone isolated from the roots of Piper mythisticum, is reported. (+)-Dihydrokawain is the natural product and is of S-configuration.
- Spino, Claude,Mayes, Nigel,Desfosses, Helene
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p. 6503 - 6506
(2007/10/03)
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