- Synthetic method for preparing amide compounds through co-catalysis of niobium pentachloride and ionic liquid
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The invention relates to a synthetic method for preparing amide compounds through co-catalysis of niobium pentachloride and ionic liquid. The preparation method is characterized by comprising the following steps: weighing organic carboxylic acid, organic amine, niobium pentachloride, ionic liquid and a molecular sieve, adding the materials into a reactor, adding an organic solvent, and reacting for 6-24 hours at the reaction temperature of 70-110 DEG C to obtain a corresponding amide product. The molar ratio of the organic carboxylic acid to the organic amine to the niobium pentachloride to the ionic liquid is 1:(1-3):(0.01-1):(0.05-1); wherein the mass ratio of the organic carboxylic acid to the molecular sieve is 1: (0.2-1). According to the method, the substrate range is expanded, the reaction yield is high (95% or above), the catalyst dosage is small, the atom economy is high, the catalyst is cheap and easy to obtain, the production cost can be greatly reduced, and the method is suitable for industrial production.
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Paragraph 0050-0052
(2020/07/13)
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- Direct amidation of non-activated carboxylic acid and amine derivatives catalyzed by TiCp2Cl2
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This paper described a mild and efficient direct amidation of non-activated carboxylic acid and amine derivatives catalyzed by TiCp2Cl2. Arylacetic acid derivatives reacted with different amines to afford the corresponding amides in good to excellent yield except of aniline. Aryl formic acids failed to react with aniline but smoothly reacted with aliphatic amines and benzylamine in moderate to good yield, fatty acids reacting with benzyl and aliphatic amines give amides in good to excellent yield. Chiral amino acids derivatives were transformed into amides without racemization in moderate yield. The possible mechanism of direct amidation catalyzed by TiCp2Cl2 was discussed. This catalytic method is very suitable for the amidation of low sterically hindered arylacetic acid, fatty acids with different low sterically hindered amines except aniline, as well as the amidation of aryl formic acid with benzyl and aliphatic amines.
- Wang, Hui,Dong, Wei,Hou, Zhipeng,Cheng, Lidan,Li, Xiufen,Huang, Longjiang
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- Air-stable Bis(pentamethylcyclopentadienyl) Zirconium Perfluorooctanesulfonate as an Efficient and Recyclable Catalyst for the Synthesis of N-substituted Amides
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Bis(pentamethylcyclopentadienyl) zirconium perfluorooctanesulfonate is an air-stable and water-tolerant Lewis acid. This complex exhibited good thermal stability and high solubility in polar organic solvents. The compound showed relatively strong acidity, with an acid strength of 0.8Ho≤3.3, and high catalytic efficiency for the synthesis of N-substituted amides via the reaction of carboxylic acids with amines, the Ritter reaction of nitriles with alcohols, and the amination of alcohols with amides. Moreover, the complex had good reusability. This catalytic system affords a simple and efficient way to synthesize N-substituted amides.
- Li, Ningbo,Wang, Lingxiao,Zhang, Liting,Zhao, Wenjie,Qiao, Jie,Xu, Xinhua,Liang, Zhiwu
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p. 3532 - 3538
(2018/08/01)
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- Tetramethyl Orthosilicate (TMOS) as a Reagent for Direct Amidation of Carboxylic Acids
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Tetramethyl orthosilicate (TMOS) is shown to be an effective reagent for direct amidation of aliphatic and aromatic carboxylic acids with amines and anilines. The amide products are obtained in good to quantitative yields in pure form directly after workup without the need for any further purification. A silyl ester as the putative activated intermediate is observed by NMR methods. Amidations on a 1 mol scale are demonstrated with a favorable process mass intensity.
- Braddock, D. Christopher,Lickiss, Paul D.,Rowley, Ben C.,Pugh, David,Purnomo, Teresa,Santhakumar, Gajan,Fussell, Steven J.
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supporting information
p. 950 - 953
(2018/02/23)
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- [...] - Orn (ClCH2NH) - AA - benzylamine, its synthesis, activity and application (by machine translation)
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The invention discloses the following formula of 13 for β - Carboline -3 - formyl - Orn (ClCH2 NH) - AA - NHCH2 C6 H5 (In the formula AA is selected from L - Arg, L - Asn, L - Asp, L - Glu, L - Gly, L - Ile, L - Leu, L - Met, L - Phe, L - Pro, L - Thr, L - Trp, L - Val residue), discloses a process for their preparation, discloses their inhibition of tumor cell growth, therefore this invention discloses their use as anti-tumor medicament. (by machine translation)
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Paragraph 0041; 0130; 0131
(2017/08/27)
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- Synthesis and antitumor activities of chiral dipeptide thioureas containing an alpha-aminophosphonate moiety
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Thiourea derivatives demonstrate potent cytotoxic activity against various leukemias and many tumor cell lines. In our previous study, the combination of thiourea and phosphonate has been proven as an effective strategy for developing antitumor agents. Herein, we synthesized and evaluated a series of novel chiral dipeptide thioureas containing an α-aminophosphonate moiety as antitumor agents. Finally, we developed novel dipeptide thioureas 11d and 11f that showed comparable inhibition with that of Cisplatin against BGC-823 and A-549 cells, respectively.
- Liu, Jingzi,Liao, Peng,Hu, Junfeng,Zhu, Hong,Wang, Yonglin,Li, Yongjun,Li, Yan,He, Bin
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- Chiral Lewis Base-Catalyzed, Enantioselective Reduction of Unprotected β-Enamino Esters with Trichlorosilane
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Catalytic asymmetric reduction of N-unsubstituted β-enamino esters represents a major challenge for asymmetric catalysis. In this paper, the first organocatalytic system that could be used for the asymmetric hydrosilylation of N-unsubstituted β-enamino esters has been developed. Using N-tert-butylsulfinyl-L-proline-derived amides and L-pipecolinic acid-derived formamides as catalyst, a broad range of β-aryl- and β-alkyl-substituted free β-amino esters could be prepared with high yields and enantioselectivities. The practicality was illustrated by the gram-scale asymmetric synthesis of ethyl (R)-3-amino-3-phenylpropanoate and isopropyl (S)-3-amino-4-(2,3,5-trifluorophenyl)butanoate. The resulting product can be smoothly transformed to the FDA approved medicines dapoxetine and sitagliptin in a short synthetic route.
- Ye, Jianheng,Wang, Chao,Chen, Lin,Wu, Xinjun,Zhou, Li,Sun, Jian
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supporting information
p. 1042 - 1047
(2016/04/19)
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- Nickel-Catalyzed Esterification of Aliphatic Amides
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Recent studies have demonstrated that amides can be used in nickel-catalyzed reactions that lead to cleavage of the amide C?N bond, with formation of a C?C or C?heteroatom bond. However, the general scope of these methodologies has been restricted to amides where the carbonyl is directly attached to an arene or heteroarene. We now report the nickel-catalyzed esterification of amides derived from aliphatic carboxylic acids. The transformation requires only a slight excess of the alcohol nucleophile and is tolerant of heterocycles, substrates with epimerizable stereocenters, and sterically congested coupling partners. Moreover, a series of amide competition experiments establish selectivity principles that will aid future synthetic design. These studies overcome a critical limitation of current Ni-catalyzed amide couplings and are expected to further stimulate the use of amides as synthetic building blocks in C?N bond cleavage processes.
- Hie, Liana,Baker, Emma L.,Anthony, Sarah M.,Desrosiers, Jean-Nicolas,Senanayake, Chris,Garg, Neil K.
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supporting information
p. 15129 - 15132
(2016/11/25)
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- Catalytic chemical amide synthesis at room temperature: One more step toward peptide synthesis
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An efficient method has been developed for direct amide bond synthesis between carboxylic acids and amines via (2-(thiophen-2-ylmethyl)phenyl)boronic acid as a highly active bench-stable catalyst. This catalyst was found to be very effective at room temperature for a large range of substrates with slightly higher temperatures required for challenging ones. This methodology can be applied to aliphatic, α-hydroxyl, aromatic, and heteroaromatic acids as well as primary, secondary, heterocyclic, and even functionalized amines. Notably, N-Boc-protected amino acids were successfully coupled in good yields with very little racemization. An example of catalytic dipeptide synthesis is reported.
- Mohy El Dine, Tharwat,Erb, William,Berhault, Yohann,Rouden, Jacques,Blanchet, Jér?me
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p. 4532 - 4544
(2015/05/13)
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- Targeting the Src Homology 2 (SH2) Domain of Signal Transducer and Activator of Transcription 6 (STAT6) with Cell-Permeable, Phosphatase-Stable Phosphopeptide Mimics Potently Inhibits Tyr641 Phosphorylation and Transcriptional Activity
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Signal transducer and activator of transcription 6 (STAT6) transmits signals from cytokines IL-4 and IL-13 and is activated in allergic airway disease. We are developing phosphopeptide mimetics targeting the SH2 domain of STAT6 to block recruitment to phosphotyrosine residues on IL-4 or IL-13 receptors and subsequent Tyr641 phosphorylation to inhibit the expression of genes contributing to asthma. Structure-affinity relationship studies showed that phosphopeptides based on Tyr631 from IL-4Rα bind with weak affinity to STAT6, whereas replacing the pY+3 residue with simple aryl and alkyl amides resulted in affinities in the mid to low nM range. A set of phosphatase-stable, cell-permeable prodrug analogues inhibited cytokine-stimulated STAT6 phosphorylation in both Beas-2B human airway cells and primary mouse T-lymphocytes at concentrations as low as 100 nM. IL-13-stimulated expression of CCL26 (eotaxin-3) was inhibited in a dose-dependent manner, demonstrating that targeting the SH2 domain blocks both phosphorylation and transcriptional activity of STAT6.
- Mandal, Pijus K.,Morlacchi, Pietro,Knight, J. Morgan,Link, Todd M.,Lee, Gilbert R.,Nurieva, Roza,Singh, Divyendu,Dhanik, Ankur,Kavraki, Lydia,Corry, David B.,Ladbury, John E.,McMurray, John S.
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p. 8970 - 8984
(2015/12/09)
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- Hafnium-catalyzed direct amide formation at room temperature
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Herein, the first example of a metal-catalyzed protocol for direct amidation of nonactivated carboxylic acids at ambient temperature (26 °C) is presented. The mild reaction conditions give rise to high yields of a range of amides in reaction times as short as 90 min, employing a commercial hafnium complex, [Hf(Cp)2Cl2], as catalyst. Amino acids are transformed into their corresponding amides without racemization, and the catalyst displays full selectivity for the amidation of carboxylic acids over esters. Electronic properties of the carboxylic acids were found to have a strong influence on the rate of the amidation reaction, and the need for a balanced amount of molecular sieves was observed to be highly important for optimal reaction outcome.
- Lundberg, Helena,Adolfsson, Hans
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p. 3271 - 3277
(2015/06/16)
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- Asymmetric transfer hydrogenation reaction in water: Comparison of chiral proline amide/amine ruthenium(II) complexes
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Chiral proline amide/amine ligands (2, 3), synthesized by multi-step reaction starting from l-proline (1), were evaluated as catalyst generated in situ from [RuCl2(p-cymene)]2 for asymmetric transfer hydrogenation of aromatic ketones in the presence of sodium formiate and sodium dodecyl sulfate (SDS). The results revealed that efficiencies and enantioselectivities strongly depend on the N-substituents.
- Denizalti, Serpil,Mercan, Deniz,?en, Betül,G?k?e, Ayta? Gürhan,?etinkaya, Bekir
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- A multigram-scale lower E-factor procedure for MIBA-catalyzed direct amidation and its application to the coupling of alpha and beta aminoacids
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The development of direct and atom-economical amidation methods is of high priority because of the importance of amides and peptides as components of pharmaceuticals and commodity chemicals. This article describes the identification of more economical and more practical conditions for direct amidation of carboxylic acids and amines using the MIBA catalyst (5-methoxy-2-iodophenylboronic acid, 6) and its application to the coupling of α- and β-amino acid derivatives. It is now possible to use half of the quantity of molecular sieves prescribed in the original procedure, at a higher concentration leading to a reduction of waste and a substantially improved E-factor. This procedure was validated in the multigram scale preparation of prototypical amides, including aminoacids, using toluene as the solvent. Because of substrate inhibition of the catalyst with monoprotected α-aminoacids, the use of doubly-protected N-phthaloyl α-aminoacids or α-azidoacids is required in order to produce dipeptide products in moderate yields. β-Aminoacids do not suffer from this problem, and Boc-β-aminoacids can be coupled successfully. Unlike other boronic acid catalysts, 6 is active under ambient and low-heat conditions, which helps prevent any epimerization of chiral α-aminoacid derivatives.
- Fatemi, Solmaz,Gernigon, Nicolas,Hall, Dennis G.
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p. 4016 - 4028
(2015/07/15)
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- Lanthanum(III) triflate catalyzed direct amidation of esters
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Lanthanum trifluoromethanesulfonate is an effective single-component catalyst for synthesizing a variety of amides directly from esters and amines under mild conditions. Highly selective amidation of esters and amines, as well as catalyst-controlled amidation of esters, demonstrated the effectiveness of the catalyst system.
- Morimoto, Hiroyuki,Fujiwara, Risa,Shimizu, Yuhei,Morisaki, Kazuhiro,Ohshima, Takashi
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supporting information
p. 2018 - 2021
(2014/05/06)
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- Facile preparation of amides from carboxylic acids and amines with ion-supported Ph3P
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Ion-supported Ph3P, 4-(diphenylphosphino)benzyltrimethylammonium bromide (IS-Ph3P), could be used for the facile amidation of a wide range of carboxylic acids with amines in the presence of bromotrichloromethane to provide the corresponding amides in good yields. In the present reaction, the desired amides were obtained in good yields with high purity by simple extraction of the reaction mixture with diethyl ether or chloroform and subsequent removal of the solvent from the extract. Moreover, ion-supported Ph3PO (IS-Ph3PO), which was a co-product derived from IS-Ph3P in the present reductive condensation, was recovered in high yield and could be reduced to IS-Ph3P for reuse in the same amidation of carboxylic acid.
- Kawagoe, Yuhsuke,Moriyama, Katsuhiko,Togo, Hideo
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p. 3971 - 3977
(2013/06/27)
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- Direct amidation of amino acid derivatives catalyzed by arylboronic acids: Applications in dipeptide synthesis
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The direct amidation of amino acid derivatives catalyzed by arylboronic acids has been examined. The reaction was generally slow relative to simple amine-carboxylic acid combinations though proceeded at 65-68 °C generally avoiding racemization. 3,4,5-Trifluorophenylboronic and o-nitrophenylboronic acids were found to be the best catalysts, though for slower dipeptide formations, high catalyst loadings were required and an interesting synergistic catalytic effect between two arylboronic acids was discovered. Arylboronic acids can be used to catalyze the direct amide formation of protected amino acid derivatives. For less reactive amino acids, cooperative catalysis can be used involving two arylboronic acids, one electron-rich and one electron-deficient, at high catalyst loadings to give good conversions at moderate temperatures. Copyright
- Liu, Shouxin,Yang, Yihua,Liu, Xinwei,Ferdousi, Farhana K.,Batsanov, Andrei S.,Whiting, Andrew
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p. 5692 - 5700
(2013/09/12)
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- Discovery and SAR studies of methionine-proline anilides as dengue virus NS2B-NS3 protease inhibitors
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A series of methionine-proline dipeptide derivatives and their analogues were designed, synthesized and assayed against the serotype 2 dengue virus NS2B-NS3 protease, and methionine-proline anilides 1 and 2 were found to be the most active DENV 2 NS2B-NS3 competitive inhibitors with Ki values of 4.9 and 10.5 μM. The structure and activity relationship and the molecular docking revealed that l-proline, l-methionine and p-nitroaniline in 1 and 2 are the important characters in blocking the active site of NS2B-NS3 protease. Our current results suggest that the title dipeptidic scaffold represents a promising structural core to discover a new class of active NS2B-NS3 competitive inhibitors.
- Zhou, Guo-Chun,Weng, Zhibing,Shao, Xiaoxia,Liu, Fang,Nie, Xin,Liu, Jinsong,Wang, Decai,Wang, Chunguang,Guo, Kai
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supporting information
p. 6549 - 6554
(2014/01/06)
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- Direct synthesis of amides from carboxylic acids and amines using B(OCH2CF3)3
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B(OCH2CF3)3, prepared from readily available B2O3 and 2,2,2-trifluoroethanol, is as an effective reagent for the direct amidation of a variety of carboxylic acids with a broad range of amines. In most cases, the amide products can be purified by a simple filtration procedure using commercially available resins, with no need for aqueous workup or chromatography. The amidation of N-protected amino acids with both primary and secondary amines proceeds effectively, with very low levels of racemization. B(OCH2CF3)3 can also be used for the formylation of a range of amines in good to excellent yield, via transamidation of dimethylformamide.
- Lanigan, Rachel M.,Starkov, Pavel,Sheppard, Tom D.
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p. 4512 - 4523
(2013/06/05)
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- XtalFluor-E, an efficient coupling reagent for amidation of carboxylic acids
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Amides were produced from carboxylic acids and amines by using XtalFluor-E as an activator. Even poorly reactive carboxylic acids can be transformed to amides. In addition, optically active amines and/or carboxylic acids were not epimerized/racemized during the process.
- Orliac, Aurélie,Gomez Pardo, Domingo,Bombrun, Agnès,Cossy, Janine
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supporting information
p. 902 - 905
(2013/03/29)
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- The phosphate-carboxylate mixed-anhydride method: A mild, efficient process for ester and amide bond construction
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A highly efficient carboxylate-phosphate anhydride pathway is described for the direct, economical synthesis of esters and amides from carboxylic acids and alcohols or amines. The reaction proceeds with retention of configuration with both chiral secondary alcohols and α-amino acid derivatives allowing access to useful chiral auxiliaries, ligands, and organocatalysts. Ester and amide products can be isolated directly in high yield due to the water soluble nature of the side products.
- McNulty, James,Vemula, Ramesh,Krishnamoorthy, Venkatesan,Robertson, Al
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experimental part
p. 5415 - 5421
(2012/09/08)
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- Transamidation of primary amides with amines using hydroxylamine hydrochloride as an inorganic catalyst
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Metal-free catalysis: A method for the transamidation of primary amides with primary or secondary amines provides access to secondary and tertiary amides, by utilizing catalytic quantities of hydroxylamine hydrochloride to activate the chemically robust primary amide group (see scheme). A mechanism of primary amide activation through a hydrogen-bonding complex is proposed. Copyright
- Allen, C. Liana,Atkinson, Benjamin N.,Williams, Jonathan M. J.
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supporting information; experimental part
p. 1383 - 1386
(2012/04/18)
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- Titanium(IV) isopropoxide as an efficient catalyst for direct amidation of nonactivated carboxylic acids
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Secondary and tertiary amides are formed in high yields, in an efficient and environmentally benign titanium(IV) isopropoxide catalyzed direct amidation of carboxylic acids with primary and secondary amines. Georg Thieme Verlag Stuttgart ? New York.
- Lundberg, Helena,Tinnis, Fredrik,Adolfsson, Hans
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supporting information
p. 2201 - 2204
(2012/10/30)
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- Direct amide coupling of non-activated carboxylic acids and amines catalysed by zirconium(IV) chloride
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Amidst the green: A green, mild and effective protocol for the direct formation of secondary and tertiary amides from non-activated carboxylic acids and amines in good to excellent yields by employing ZrCl4 as the catalyst is presented (see scheme). The amide coupling protocol proved to be suitable for scaled up syntheses, and the mild reaction conditions conserve the enantiopurity of chiral starting materials. Copyright
- Lundberg, Helena,Tinnis, Fredrik,Adolfsson, Hans
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supporting information; experimental part
p. 3822 - 3826
(2012/05/20)
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- Direct asymmetric α-allylation of ketones with allylic alcohols Via Pd/enamine cooperative function
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Direct asymmetric α-allylation of ketones with allylic alcohols is described. The combination of palladium with a new phosphine ligand bearing a chiral proline moiety promoted the reaction to afford the corresponding α-allylated ketones in moderate yield and enantioselectivity.
- Yasuda, Shigeo,Kumagai, Naoya,Shibasaki, Masakatsu
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p. 745 - 757
(2013/08/15)
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- Transamidation of primary amides with amines catalyzed by zirconocene dichloride
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Zirconocene dichloride (Cp2ZrCl2) has been shown to be an effective catalyst for the transamidation of primary amides with amines in cyclohexane at 80°C in 5-24 hours. For favourable substrates, the reaction can be performed at temperatures as low as 30°C.
- Atkinson, Benjamin N.,Chhatwal, A. Rosie,Lomax, Helen V.,Walton, James W.,Williams, Jonathan M. J.
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supporting information
p. 11626 - 11628,3
(2012/12/12)
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- Transamidation of primary amides with amines catalyzed by zirconocene dichloride
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Zirconocene dichloride (Cp2ZrCl2) has been shown to be an effective catalyst for the transamidation of primary amides with amines in cyclohexane at 80°C in 5-24 hours. For favourable substrates, the reaction can be performed at temperatures as low as 30°C.
- Atkinson, Benjamin N.,Chhatwal, A. Rosie,Lomax, Helen V.,Walton, James W.,Williams, Jonathan M. J.
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supporting information
p. 11626 - 11628
(2013/01/15)
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- Sodium methoxide: A simple but highly efficient catalyst for the direct amidation of esters
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A simple NaOMe catalyst provides superior accessibility to a wide variety of functionalized amides including peptides through direct amination of esters in an atom-economical and environmentally benign way.
- Ohshima, Takashi,Hayashi, Yukiko,Agura, Kazushi,Fujii, Yuka,Yoshiyama, Asako,Mashima, Kazushi
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supporting information; experimental part
p. 5434 - 5436
(2012/07/03)
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- Chiral lewis base catalyzed highly enantioselective reduction of N-alkyl β-enamino esters with trichlorosilane and water
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First, test the water! In the presence of a chiral Lewis base catalyst 2, the supposedly moisture-unfriendly reduction system with trichlorosilane was found to be highly efficient and enantioselective when using water as an additive. For the first time, this method enables the reduction of a broad range of N-alkyl β-enamino esters 1 to give N-alkyl β-amino esters 3 in good to high yields and with excellent enantioselectivities (see scheme).
- Wu, Xinjun,Li, Yang,Wang, Chao,Zhou, Li,Lu, Xiaoxia,Sun, Jian
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supporting information; experimental part
p. 2846 - 2848
(2011/04/24)
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- The catalytic potential of 4-guanidinylpyridines in acylation reactions
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A series of 3-alkyl-4-guanidinylpyridines with variable alkylation pattern have been synthesized and characterized with respect to their catalytic potential in acylation reactions of alcohols. The ability of the substitution pattern to stabilize acylpyridinium cations, which act as critical intermediates in the catalytic cycle of pyridine-catalyzed acylation reactions, has been assessed at the MP2(FC)/6-31+G(2d,p)//B98/6-31G(d) level of theory and inclusion of solvent effects in chloroform using the PCM continuum solvation model. The most active 4-guanidinylpyridines are among those having the most electron-rich pyridine ring. The influence of the type and concentration of the auxiliary base on the catalytic activity has also been studied. While the change from triethylamine to N,N-diisopropylethylamine as the auxiliary base does not lead to a systematic increase or decrease in the catalytic rates, the complete absence of auxiliary base leads to a 27-fold reduction in reaction rate. Georg Thieme Verlag Stuttgart.
- Held, Ingmar,Larionov, Evgeny,Bozler, Christian,Wagner, Felicia,Zipse, Hendrik
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experimental part
p. 2267 - 2277
(2009/12/31)
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- A new chiral synthesis of Wieland-Miescher ketone catalyzed by a combination of (S)-N- benzyl-N(2-pyrrolidinylmethyl)amine derivative and bronsted acid
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New or known N-benzyl-N (2-pyrrolidinylmethyl)amine derivatives bearing a variety of substituents on the aromatic ring were easily prepared from N-Boc-proline or NBoc-prolinol. The enantioselectivity of the intramolecular asymmetric aldol reaction mediated by a combination of the amine derivative and Bronsted acid to prepare Wieland-Miescher ketone was examined in detail. During the examination, remarkable substitutional effects on the aromatic ring were observed. Development of a catalytic version of the reaction was successfully achieved by the use of N(9-anthracenyl)methyl-N(2-pyrrolidinyl-methyl)amine in the presence of dichloroacetic acid.
- Akahane, Yuichi,Inomata, Kohei,Endo, Yasuyuki
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experimental part
p. 1065 - 1078
(2010/10/03)
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- 2(S)-(Cycloalk-1-enecarbonyl)-1-(4-phenyl-butanoyl)pyrrolidines and 2(S)-(aroyl)-1-(4-phenylbutanoyl)pyrrolidines as prolyl oligopeptidase inhibitors
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In order to replace the P2-P1 amide group, different 1-cycloalkenyls and 2-aryls were studied in the place of the P1 pyrrolidine group of a 4-phenylbutanoyl-l-Pro-pyrrolidine structure, which is a well-known prolyl oligopeptidase inhibitor SUAM-1221. The
- Jarho, Elina M.,Venaelaeinen, Jarkko I.,Poutiainen, Sami,Leskinen, Harri,Vepsaelaeinen, Jouko,Christiaans, Johannes A.M.,Forsberg, Markus M.,Maennistoe, Pekka T.,Wallen, Erik A.A.
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p. 2024 - 2031
(2007/10/03)
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- Asymmetric direct aldol reaction catalysed by L-prolinethioamides
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L-Prolinethioamides have been found to be active catalysts for direct aldol reactions of acetone with aromatic aldehydes, affording aldol products in good yields and with good enantioselectivities. They were prepared from L-proline and simple aliphatic and aromatic amines in optically pure form and in good overall yields. Studies employing ten catalysts allowed us to unequivocally establish the basic principles governing the outcome of the L-prolinethioamide-catalysed aldol reaction. In particular, the catalyst prepared from L-proline and (S)-phenylethylamine catalysed the reaction of acetone with 4-cyanobenzaldehyde in 57 % yield and 93 % ee (100% ee at -78°C). Most importantly, we found that steric interaction between the catalyst and a donor or an acceptor is crucial for the stereoselectivity of the aldol addition, while the unwanted formation of imidazolidinethione (from the catalyst and acetone or an aldehyde) was shown to decrease both the ee and the yield. The influence of the amine moiety (-CSNHR), different solvents and temperatures were studied, and we also found that there is a linear correlation between the optical purity of the catalyst and the ee of the aldol product, which supports the hypothesis that the reaction proceeds by the enamine-imine mechanism, involving only one molecule of the catalyst in the transition state. For the first time, the formation of 1,5-dihydroxypentan-3-one products (double addition products) was studied in detail. By precise optimisation we were able to show that the courses of the reactions of acetone with highly reactive aromatic aldehydes could be manipulated to give either the aldol products or 1,5-dihydroxypentan-3-one derivatives as the major product in moderate ee. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Gryko, Dorota,Lipinski, Radoslaw
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p. 3864 - 3876
(2007/10/03)
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- Compounds for treating tumors
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The invention provides compounds of formula (I): wherein E, A, B′, R6, R7, R8, and R9 are defined in the specification which compounds exhibit anticancer activity and are useful for treating cancer.
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- Asymmetric cyanosilylation of aldehydes catalyzed by novel organocatalysts
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A novel proline-based N,N′-dioxide, which is easily prepared from inexpensive chemicals, serves as an effective catalyst for enantioselective cyanosilylation of aldehydes in up to 73% ee. Georg Thieme Verlag Stuttgart.
- Wen, Yuehong,Huang, Xiao,Huang, Jinglun,Xiong, Yan,Qin, Bo,Feng, Xiaoming
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p. 2445 - 2448
(2007/10/03)
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- NOVEL COMPOUNDS OF PROLINE AND MORPHOLINE DERIVATIVES
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The present invention relates to compounds with the formulas (I), (II), and (III), or a pharmaceutically acceptable salt thereof: wherein T is a (4 to 10)-membered heterocyclyl selected from the group consisting of and wherein R1. R2 and R3 are as defined in the specification. The invention also relates to pharmaceutical compositions comprising the compounds of formulas (I), (II), and (III) and methods of treating a condition that is mediated by the modulation of the 11-β-hsd-1 enzyme, the method comprising administering to a mammal an effective amount of a compound of formulas (I), (II), and (III).
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Page/Page column 46
(2008/06/13)
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- L-prolinethioamides - Efficient organocatalysts for the direct asymmetric aldol reaction
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A series of novel L-proline derived thioamides has been synthesised. They have been evaluated as organocatalysts in the direct asymmetric aldol reaction for the first time. Thioamides exhibit catalytic ability higher than proline itself and the model aldol reaction of 4-cyanobenzaldehyde with acetone proceeds well in the presence of 5 mol % of catalyst (ee up to 100%). Other aromatic aldehydes gave aldol products with high ees and moderate yields. Small changes in the catalyst's structure [e.g., N-Bn versus N-CH(CH3)Ph] as well as the addition of an acid have a profound effect on their activity. The unexpected formation of the catalyst-derived cyclic adducts was observed and their reactivity was established giving valuable insight into the course of the reaction.
- Gryko, Dorota,Lipinski, Radoslaw
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p. 1948 - 1952
(2007/10/03)
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- Two alternative conformational states of α,α-dialkylglycyl-L-prolyl sequences governed by presence/absence of an NH group directly following the proline residue. X-Ray crystal and molecular structures of Boc-D-Iva-L-Pro-NHBzl and Boc-L-Iva-L-Pro-NHBzl
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The crystal structures of the isovaline-contatinig dipeptides, Boc-D-Iva-L-Pro-NHBzl 4 and Boc-L-Iva-L-Pro-NHBzl 5 were determined by X-ray diffraction.The diastereomeric peptides adopt intramolecular hydrogen-bonded β-turn conformations closely similar to each other (4: φIva -51 deg, ψIva -38 deg C, φPro - 70 deg C and ψPro -17 deg C and 5: φIva -53 deg C, φPro -72 deg C and ψPro -14 deg C).The Pro ring of each peptide is in Cγ-exo conformation.These conformations are essentially the same as those in the reported crystal structures of the Aib-L-Pro sequence possessing an NH group directly attached to the carbonyl of the L-Pro, indicating that replacement of either one of the two methyl groups of the Aib moiety with an ethyl group does not cause any significant change in the β-turn conformation of the Aib-L-Pro sequence in the crystalline state.CD spectral analysis of the terminal chromophoric group-carrying peptides Dnp-Gly-X-L-Pro-Gly-pNa (X = Aib 6 and D/L-Iva 7/8) has shown that these three tetrapeptides in CHCl3 and THF solutions also adopt a β-turn-type conformation.CD spectra of glycolic acid residue-containing analogues in place of the fourth Gly residue revealed a lack of β-turn tendency in these analogues, indicating the importance of intramolecular hydrogen bonding for the β-turn conformation of the central dipeptide moieties.The results are consistent with the reported unturned crystal structures of Aib-L-Pro and D/L-Iva-L-Pro sequence-containing peptides lacking the NH group which directly follows the Pro residue available for intramolecular hydrogen bonding.
- Kawai, Masao,Omori, Yoshimasa,Yamamura, Hatsuo,Butsugan, Yasuo,Taga, Tooru,Miwa, Yishihisa
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p. 2115 - 2122
(2007/10/02)
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