- Minisci-Type Alkylation of N-Heteroarenes by N-(Acyloxy)phthalimide Esters Mediated by a Hantzsch Ester and Blue LED Light
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A synthetic method that enables the Hantzsch ester-mediated Minisci-type C2-alkylation of quinolines, isoquinolines and pyridines by N-(acyloxy)phthalimide esters (NHPI) under blue LED (light emitting diode) light (456 nm) is described. Achieved under mild reaction conditions at room temperature, the metal-free synthetic protocol was shown to be applicable to primary, secondary and tertiary NHPIs to give the alkylated N-heterocyclic products in yields of 21–99%. On introducing a chiral phosphoric acid, an asymmetric version of the reaction was also realised and provided product enantiomeric excess (ee) values of 53–99%. The reaction mechanism was delineated to involve excitation of an electron-donor acceptor (EDA) complex, formed from weak electrostatic interactions between the Hantzsch ester and NHPI, which generates the posited radical species of the redox active ester that undergoes addition to the N-heterocycle.
- Kyne, Sara Helen,Li, Jiacheng,Siang Tan, Suan,Wai Hong Chan, Philip
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supporting information
(2022/01/11)
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- Bio- And Medicinally Compatible α-Amino-Acid Modification via Merging Photoredox and N-Heterocyclic Carbene Catalysis
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An N-heterocyclic carbene and photoredox cocatalyzed α-amino-acid decarboxylative carbonylation reaction is presented. This method displays good scope generality, providing a direct pathway to access various downstream α-amino ketones under bio- and medicinally compatible conditions. Moreover, this strategy is appealing to chemical biology because it has great potential for the chemical modification of peptides or the late-stage synthesis of keto-peptides.
- Chen, Lei,Du, Ding,Feng, Jie,Gao, Jian,Lu, Tao,Ma, Rui,Shi, Zhihao,Zhang, Kuili
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supporting information
(2020/09/02)
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- Direct Synthesis of Free α-Amino Acids by Telescoping Three-Step Process from 1,2-Diols
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A practical telescoping three-step process for the syntheses of α-amino acids from the corresponding 1,2-diols has been developed. This process enables the direct synthesis of free α-amino acids without any protection/deprotection step. This method was also effective for the preparation of a 15N-labeled α-amino acid. 1,2-Diols bearing α,β-unsaturated ester moieties afforded bicyclic α-amino acids through intramolecular [3 + 2] cycloadditions. A preliminary study suggests that the resultant α-amino acids are resolvable by aminoacylases with almost complete selectivity.
- Inada, Haruki,Shibuya, Masatoshi,Yamamoto, Yoshihiko
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supporting information
p. 709 - 713
(2019/01/25)
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- Preparation of cross-linked enzyme aggregates of l-aminoacylase via co-aggregation with polyethyleneimine
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l-Aminoacylase from Aspergillus melleus was co-aggregated with polyethyleneimine and subsequently cross-linked with glutaraldehyde to obtain aminoacylase-polyethyleneimine cross-linked enzyme aggregates (termed as AP-CLEA). Under the optimum conditions, AP-CLEA expressed 74.9% activity recovery and 81.2% aggregation yield. The said method of co-aggregation and cross-linking significantly improved the catalytic stability of l-aminoacylase with respect to temperature and storage. AP-CLEA were employed for enantioselective synthesis of three unnatural amino acids (namely: phenylglycine, homophenylalanine and 2-naphthylalanine) via chiral resolution of their ester-, amide- and N-acetyl derivatives. The enantioselectivity of AP-CLEA was the highest for hydrolysis of amino acid amides; was moderate for hydrolysis of N-acetyl amino acids and was the least for hydrolysis of amino acid esters. Furthermore, AP-CLEA were found to retain more than 92% of the initial activity after five consecutive batches of (RS)-homophenylalanine hydrolysis suggesting an adequate operational stability of the biocatalyst.
- Vaidya, Bhalchandra K.,Kuwar, Suyog S.,Golegaonkar, Sandeep B.,Nene, Sanjay N.
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experimental part
p. 184 - 191
(2012/03/22)
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- METHOD OF AMIDOCARBONYLATION REACTION
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A novel method of an amidocarbonylation reaction among an aldehyde compound, an amide compound, and carbon monoxide, which comprises using a palladium-supporting crosslinked-polymer composition containing palladium clusters having a major-axis length of 20 nm or shorter to conduct the amidocarbonylation reaction. Thus, an N-acyl-±-amino acid can be more efficiently and selectively synthesized in a clean reaction system. Also provided is a catalyst for use in the method.
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Page/Page column 11
(2008/06/13)
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- Enzymatic resolution of N-acetyl-homophenylalanine with mammalian kidney acetone powders
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Kidney acetone powders (KAP) from beef, dog, hog, rat, and sheep have been evaluated for resolving N-acetyl-DL-homophenylalanine. We also propose a simple protocol for the preparation of both enantiomers of homophenylalanine by enzymatic resolution using mammalian KAP. The beef kidney afforded the best results, rendering the highest isolated yields, 37.5% and 41% and enantiomeric excesses of 94% and 99% for both D-N-Ac-homophenylalanine and L-homophenylalanine, respectively.
- Regla, Ignacio,Luna, Hector,Perez, Herminia I.,Demare, Patricia,Bustos-Jaimes, Ismael,Zaldivar, Victor,Calcagno, Mario L.
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p. 1285 - 1288
(2007/10/03)
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- Application of aminoacylase I to the enantioselective resolution of α-amino acid esters and amides
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Aminoacylase I from Aspergillus melleus, a readily available and inexpensive enzyme mainly used in the industrial production of enantiopure L-amino acids from their N-acetyl derivatives, is shown to hydrolyze the esters and amides of natural and non-natural amino acids with high enantioselectivity (for the ester hydrolysis, E is up to 76, in case of amides E >300). The reaction rates of amide and ester hydrolysis are comparable, and in some cases these conversions proceeded even faster than 'traditional' aminoacylase- catalyzed hydrolysis of N-acetyl derivatives thus providing new possibilities for the resolution of the corresponding racemates. This novel approach provides an alternative route for the biocatalytic production of optically active amino acids and their derivatives.
- Youshko, Maxim I.,Van Langen, Luuk M.,Sheldon, Roger A.,Svedas, Vytas K.
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p. 1933 - 1936
(2007/10/03)
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- A novel tea-bag methodology for enzymatic resolutions of α-amino acid derivatives in reverse micellar media
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A novel tea bag methodology for resolution of methyl esters of N-acetyl- α-amino acids in reverse micellar medium of bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) in isooctane-chloroform using immobilized enzymes or microbial cells is presented. The methodology effectively solves the problems of substrate solubility, product separation and surfactant recycling and provides products in high yields (80 to 90%) and excellent optical purities (% ee 97 to >99%).
- Bhalerao,Rao,Fadnavis
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p. 2109 - 2118
(2007/10/02)
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- Studies on angiotensin converting enzyme inhibitors. VI. Synthesis and angiotensin converting enzyme inhibitory activities of the dicarboxylic acid derivative of imidapril and its diastereoisomers
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All possible diastereoisomers of the dicarboxylic acid (10a), the biologically active form of imidapril (1), were synthesized, and their inhibitory activity against angiotensin converting enzyme (ACE) was examined. The in vitro ACE inhibitory activity of these compounds greatly depended on the configurations of the three asymmetric carbons in each molecule. The (S,S,S) isomer (10a) showed much more potent activity than the others.
- Kubota,Nunami,Hayashi,Hashimoto,Ogiku,Matsuoka,Ishida
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p. 1619 - 1622
(2007/10/02)
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- Studies on Angiotensin Converting Enzyme Inhibitors. 4. Synthesis and Angiotensin Converting Enzyme Inhibitory Activities of 3-Acyl-1-alkyl-2-oxoimidazolidine-4-carboxylic Acid Derivatives
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(4S)-1-Alkyl-3-acyl>-2-oxoimidazolidine-4-carboxylic acid derivatives (3) were prepared by two methods.Their angiotensin converting enzyme (ACE) inhibitory activities and antihypertensive effects were evaluated, and the structure-activity relationships were discussed.The dicarboxylic acids 3a-n possessing S,S,S configuration showed potent in vitro ACE inhibitory activities with IC 50 values of 1.1x10-8-1.5x10-9 M.The most potent compound in this series, monoester 3p, had an ID 50 value of 0.24 mg/kg, po for inhibition of angiotensin I induced pressor response in normotensive rats and produced a dose-dependent decrease in systolic blood pressure of spontaneously hypertensive rats (SHRs) at doses of 1-10 mg/kg, po.
- Hayashi, Kimiaki,Nunami, Ken-ichi,Kato, Jyoji,Yoneda, Naoto,Kubo, Masami,et al.
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p. 289 - 297
(2007/10/02)
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