- MONOHYDROLYSIS OF AN ALIPHATIC DINITRILE COMPOUND BY NITRILASE FROM RHODOCOCCUS RHODOCHROUS K22
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Nitrilase from Rhodococcus rhodochrous K22 catalyzes the conversion of various aliphatic nitrile derivatives to the corresponding acids.Using this resting cells, 4-cyanobutyric acid was synthesized from glutaronitrile with 100percent molar conversion.
- Kobayashi, Michihiko,Yanaka, Noriyuki,Nagasawa, Toru,Yamada, Hideaki
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- Enzymatic halogenation and oxidation using an alcohol oxidase-vanadium chloroperoxidase cascade
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The chemo-enzymatic cascade which combines alcohol oxidase from Hansenula polymorpha (AOXHp) with vanadium chloroperoxidase (VCPO), for the production of biobased nitriles from amino acids was investigated. In the first reaction H2O2 (and acetaldehyde) are generated from ethanol and oxygen by AOXHp. H2O2 is subsequently used in the second reaction by VCPO to produce HOBr in situ. HOBr is required for the non-enzymatic oxidative decarboxylation of glutamic acid (Glu) to 3-cyanopropanoic acid (CPA), an intermediate in the production of biobased acrylonitrile. It was found that during the one pot conversion of Glu to CPA by AOXHp-VCPO cascade, AOXHp was deactivated by HOBr. To avoid deactivation, the two enzymes were separated in two fed-batch reactors. The deactivation of AOXHp by HOBr appeared to depend on the substrate: an easily halogenated compound like monochlorodimedone (MCD) was significantly converted in one pot by the cascade reaction of AOXHp and VCPO, while conversion of Glu did not occur under those conditions. Apparently, MCD scavenges HOBr before it can inactivate AOXHp, while Glu reacts slower, leading to detrimental concentrations of HOBr. Enzymatically generated H2O2 was used in a cascade reaction involving halogenation steps to enable the co-production of biobased nitriles and acetaldehyde.
- But, Andrada,van Noord, Aster,Poletto, Francesca,Sanders, Johan P.M.,Franssen, Maurice C.R.,Scott, Elinor L.
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- A bioorthogonal raman reporter strategy for SERS detection of glycans on live cells
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Direct detection of glycans on live cells using surface-enhanced Raman scattering (SERS) has been shown. A bioorthogonal Raman reporter was directly installed onto the monosaccharide analogs. Once metabolically incorporated into cell surface glycans, the Raman reporter was detected using SERS (see picture). Copyright
- Lin, Liang,Tian, Xiangdong,Hong, Senlian,Dai, Peng,You, Qiancheng,Wang, Ruyi,Feng, Lianshun,Xie, Can,Tian, Zhong-Qun,Chen, Xing
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- Towards Preparative Chemoenzymatic Oxidative Decarboxylation of Glutamic Acid
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The chemoenzymatic oxidative decarboxylation of glutamic acid to the corresponding nitrile using the vanadium chloroperoxidase from Curvularia inaequalis (CiVCPO) as HOBr generation catalysts has been investigated. Product inhibition was identified as major limitation. Nevertheless, 1630000 turnovers and kcat of 75 s?1 were achieved using 100 mM glutamate. The semi-preparative enzymatic oxidative decarboxylation of glutamate was also demonstrated.
- Xu, Xiaomin,But, Andrada,Wever, Ron,Hollmann, Frank
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- Unusual differences in the reactivity of glutamic and aspartic acid in oxidative decarboxylation reactions
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Amino acids are potential substrates to replace fossil feedstocks for the synthesis of nitriles via oxidative decarboxylation using vanadium chloroperoxidase (VCPO), H2O2 and bromide. Here the conversion of glutamic acid (Glu) and aspartic acid (Asp) was investigated. It was observed that these two chemically similar amino acids have strikingly different reactivity. In the presence of catalytic amounts of NaBr (0.1 equiv.), Glu was converted with high selectivity to 3-cyanopropanoic acid. In contrast, under the same reaction conditions Asp showed low conversion and selectivity towards the nitrile, 2-cyanoacetic acid (AspCN). It was shown that only by increasing the amount of NaBr present in the reaction mixture (from 0.1 to 2 equiv.), could the conversion of Asp be increased from 15% to 100% and its selectivity towards AspCN from 45% to 80%. This contradicts the theoretical hypothesis that bromide is recycled during the reaction. NaBr concentration was found to have a major influence on reactivity, independent of ionic strength of the solution. NaBr is involved not only in the formation of the reactive Br+ species by VCPO, but also results in the formation of potential intermediates which influences reactivity. It was concluded that the difference in reactivity between Asp and Glu must be due to subtle differences in inter- and intramolecular interactions between the functionalities of the amino acids.
- But, Andrada,Van Der Wijst, Evie,Le N?tre, Jér?me,Wever, Ron,Sanders, Johan P. M.,Bitter, Johannes H.,Scott, Elinor L.
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- Photoredox Activation of Formate Salts: Hydrocarboxylation of Alkenes via Carboxyl Group Transfer
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A photoredox activation mode of formate salts for carboxylation was developed. Using a formate salt as the reductant, carbonyl source, and hydrogen atom transfer reagent, a wide range of alkenes can be converted into acid products via a carboxyl group tra
- Huang, Yan,Hou, Jing,Zhan, Le-Wu,Zhang, Qian,Tang, Wan-Ying,Li, Bin-Dong
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p. 15004 - 15012
(2021/12/14)
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- Fast and pH-Independent Elimination of trans-Cyclooctene by Using Aminoethyl-Functionalized Tetrazines
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The inverse-electron-demand Diels–Alder/pyridazine elimination tandem reaction, in which the allylic substituent on trans-cyclooctene is eliminated following reaction with tetrazines, is gaining interest as a versatile bioorthogonal process. One potential shortcoming of such currently used reactions is their propensity to proceed faster and more efficiently at lower pH, a feature caused by the nature of the tetrazines used. Here, we present aminoethyl-substituted tetrazines as the first pH-independent reagents showing invariably fast elimination kinetics at all biologically relevant pH values.
- Sarris, Alexi J. C.,Hansen, Thomas,de Geus, Mark A. R.,Maurits, Elmer,Doelman, Ward,Overkleeft, Herman S.,Codée, Jeroen D. C.,Filippov, Dmitri V.,van Kasteren, Sander I.
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supporting information
p. 18075 - 18081
(2018/11/23)
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- Synthesis of α-aminonitriles using aliphatic nitriles, α-amino acids, and hexacyanoferrate as universally applicable non-toxic cyanide sources
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In cyanation reactions, the cyanide source is often directly added to the reaction mixture, which restricts the choice of conditions. The spatial separation of cyanide release and consumption offers higher flexibility instead. Such a setting was used for the cyanation of iminium ions with a variety of different easy-to-handle HCN sources such as hexacyanoferrate, acetonitrile or α-amino acids. The latter substrates were first converted to their corresponding nitriles through oxidative decarboxylation. While glycine directly furnishes HCN in the oxidation step, the aliphatic nitriles derived from α-substituted amino acids can be further converted into the corresponding cyanohydrins in an oxidative C-H functionalization. Mn(OAc)2 was found to catalyze the efficient release of HCN from these cyanohydrins or from acetone cyanohydrin under acidic conditions and, in combination with the two previous transformations, permits the use of protein biomass as a non-toxic source of HCN.
- Nauth, Alexander M.,Konrad, Tim,Papadopulu, Zaneta,Vierengel, Nina,Lipp, Benjamin,Opatz, Till
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supporting information
p. 4217 - 4223
(2018/09/29)
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- A remarkable reductive dearomatization of thiophene and furan rings
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Reduction of a 2-nitrothiophene 4 and the corresponding 2-nitrofuran 20 with zinc and acetic acid produced a remarkable dearomatization and fragmentation reaction to give acyclic nitriles 6 and 22, respectively. The intermediate 2-aminothiophene 5 was trapped by acylation with acetic anhydride to give acetamide 7. An additional acrylonitrile intermediate 17 was also trapped by Michael addition with benzyl mercaptan to give adduct 18. An alternate synthesis of nitrile 22 produced in the reduction of nitrofuran 20 provided an authentic sample of the product. The conversion of nitroaromatic heterocycles 4 and 20 into aliphatic nitriles 6 and 22 are remarkable and unprecedented reactions. Georg Thieme Verlag Stuttgart · New York.
- Nguyen, Son T.,Ding, Xiaoyuan,Peet, Norton P.
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p. 1904 - 1908
(2013/07/26)
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- Synthesis of tetrazole analogues of phosphonohydroxamic acids: An attempt to improve the inhibitory activity against the DXR
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This work is focused on the design of new antimicrobial drugs and on the development of lipophilic inhibitors of the DXR, the second enzyme of the MEP pathway for the biosynthesis of isoprene units in most bacteria, by replacing the phosphonate group of fosmidomycin derivatives by a tetrazoyl moiety capable of multiple hydrogen bonding. The N- and C-substituted tetrazole analogues of phosphonohydroxamate inhibitors were synthesized and tested on the DXR of Escherichia coli. This work points out the hypothesis that the phosphonate/phosphate recognition site might be too rigid to accommodate other functional groups.
- Nguyen-Trung, Anh Thu,Tritsch, Denis,Grosdemange-Billiard, Catherine,Rohmer, Michel
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supporting information
p. 1643 - 1647
(2013/04/10)
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- Selective oxidative decarboxylation of amino acids to produce industrially relevant nitriles by vanadium chloroperoxidase
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Industrial nitriles from biomass: Vanadium-chloroperoxidase is successfully used to transform selectively glutamic acid into 3-cyanopropanoic acid, a key intermediate for the synthesis of bio-succinonitrile and bio-acrylonitrile, by using a catalytic amount of a halide salt. This clean oxidative decarboxylation can be applied to mixtures of amino acids obtained from plant waste streams, leading to easily separable nitriles. Copyright
- But, Andrada,Le N?tre, Jér?me,Scott, Elinor L.,Wever, Ron,Sanders, Johan P. M.
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experimental part
p. 1199 - 1202
(2012/09/08)
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- Biobased synthesis of acrylonitrile from glutamic acid
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Glutamic acid was transformed into acrylonitrile in a two step procedure involving an oxidative decarboxylation in water to 3-cyanopropanoic acid followed by a decarbonylation-elimination reaction using a palladium catalyst. The Royal Society of Chemistry.
- Le Notre, Jerome,Scott, Elinor L.,Franssen, Maurice C. R.,Sanders, Johan P. M.
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supporting information; experimental part
p. 807 - 809
(2011/06/22)
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- Structural and functional characterization of plant aminoaldehyde dehydrogenase from pisum sativum with a broad specificity for natural and synthetic aminoaldehydes
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Aminoaldehyde dehydrogenases (AMADHs, EC 1.2.1.19) belong to the large aldehyde dehydrogenase (ALDH) superfamily, namely, the ALDH9 family. They oxidize polyamine-derived ω-aminoaldehydes to the corresponding ω-amino acids. Here, we report the first X-ray structures of plant AMADHs: two isoenzymes, PsAMADH1 and PsAMADH2, from Pisum sativum in complex with β-nicotinamide adenine dinucleotide (NAD+) at 2.4 and 2.15 A resolution, respectively. Both recombinant proteins are dimeric and, similarly to other ALDHs, each monomer is composed of an oligomerization domain, a coenzyme binding domain and a catalytic domain. Each subunit binds NAD+ as a coenzyme, contains a solvent-accessible C-terminal peroxisomal targeting signal (type 1) and a cation bound in the cavity close to the NAD+ binding site. While the NAD+ binding mode is classical for PsAMADH2, that for PsAMADH1 is unusual among ALDHs. A glycerol molecule occupies the substrate binding site and mimics a bound substrate. Structural analysis and substrate specificity study of both isoenzymes in combination with data published previously on other ALDH9 family members show that the established categorization of such enzymes into distinct groups based on substrate specificity is no more appropriate, because many of them seem capable of oxidizing a large spectrum of aminoaldehyde substrates. PsAMADH1 and PsAMADH2 can oxidize N,N,N-trimethyl-4-aminobutyraldehyde into γ-butyrobetaine, which is the carnitine precursor in animal cells. This activity highly suggests that in addition to their contribution to the formation of compatible osmolytes such as glycine betaine, β-alanine betaine and γ-aminobutyric acid, AMADHs might participate in carnitine biosynthesis in plants.
- Tylichova, Martina,Kopecny, David,Morera, Solange,Briozzo, Pierre,Lenobel, Rene,Snegaroff, Jacques,Sebela, Marek
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experimental part
p. 870 - 882
(2011/04/24)
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- Nitrilase-catalyzed selective hydrolysis of dinitriles and green access to the cyanocarboxylic acids of pharmaceutical importance
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To further explore its synthetic applications, the nitrilase bll6402 from Bradyrhizobium japonicum strain USDA110 has been examined toward the hydrolysis of various dinitriles. It has been found that nitrilase bll6402 effectively hydrolyzed α,ω-dinitriles to ω-cyanocarboxylic acids, and the selectivity was independent of the substrate chain length. This feature is distinct from all the known nitrilases of various sources. Nitrilase bll6402 was thus applied to the synthesis of 1-cyanocycloalkaneacetic acids, the useful precursors for the synthesis of gabapentin and its analogues.
- Zhu, Dunming,Mukherjee, Chandrani,Biehl, Edward R.,Hua, Ling
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p. 1667 - 1670
(2008/02/11)
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- Exploring the synthetic applicability of a cyanobacterium nitrilase as catalyst for nitrile hydrolysis
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The substrate specificity and synthetic applicability of the nitrilase from cyanobacterium Synechocystis sp. strain PCC 6803 have been examined. This nitrilase catalyzed the hydrolysis of both aromatic and aliphatic nitriles to the corresponding acids in high yields. Furthermore, the stereoselective hydrolysis of phenyl-substituted β-hydroxy nitriles to (S)-enriched β-hydroxy carboxylic acids and selective hydrolysis of α,ω- dinitriles with five or less methylene groups to ω-cyano carboxylic acids have been achieved. This suggested that nitrilase from Synechocystis sp. PCC 6803 could be a useful enzyme catalyst for the "green" nitrile hydrolysis. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Mukherjee, Chandrani,Zhu, Dunming,Biehl, Edward R.,Hua, Ling
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p. 5238 - 5242
(2007/10/03)
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- An insight of the reactions of amines with trichloroisocyanuric acid
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The reaction between amines or α-aminoacids with trichloroisocyanuric acid is studied under various conditions: N,N-dichloroamines, nitriles and ketones can be obtained from primary amines, while free aminoacids undergo oxidative decarboxylation to the corresponding nitrile of one less carbon atom.
- De Luca, Lidia,Giacomelli, Giampaolo
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p. 2180 - 2184
(2007/10/03)
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- Aggregation in oxidation of aspartic and glutamic acids by chloramine-T in presence of surfactants: A kinetic study
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The kinetics of oxidation of aspartic and glutamic acids by chloramine-T in HClO4 medium have been investigated in the absence and presence of anionic (sodium lauryl sulphate), cationic (cetyltrimethylammonium bromide) and non-ionic (Brij 35) surfactants. In the absence of surfactant the rate of oxidation may be represented as, d[Chloramine-T]/dt=k[Chloramine-T] 2[Amino acid]/(1+K[H+]) where k and K are constants. The presence of a small amount of surfactant (below its critical micelle concentration) strongly enhances the rate of oxidation and the observed rate constant attains constancy at higher surfactant concentration. Using Piszkiewicz's cooperativity model, the cooperative index n has been calculated for these reactions to be between 1-3, indicating the existence of catalytically productive submicellar aggregates. The values of n have been used to calculate the binding constants of reactants with the surfactant using Raghvan and Srinivasan's model proposed for biomolecular micellar catalysed reactions. The evaluated binding constants are in good agreement from those obtained by Piszkiewicz's model. The formation of aggregate is further supported by the enhancement of rate in presence of a common hydrotrope, namely, sodium benzoate.
- Pandey, Ekta,Grover, Neeti,Kambo, Neelu,Upadhyay, Santosh K.
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p. 1186 - 1192
(2007/10/03)
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- One-pot sequence for the decarboxylation of α-amino acids
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Treatment of an α-amino acid with N-bromosuccinimide in water at pH 5 or in an alcoholic-aqueous ammonium chloride mixture, followed by addition of nickel(II) chloride and sodium borohydride, effected an overall decarboxylation via an intermediate nitrile to afford the corresponding amine in good yield.
- Laval, Gilles,Golding, Bernard T.
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p. 542 - 546
(2007/10/03)
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- Selective hydrolysis of aliphatic dinitriles to monocarboxylic acids by a nitrilase from Arabidopsis thaliana
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The hydrolysis of a variety of dinitriles including α,ω-dicyanoalkanes 1, β-substituted glutaronitriles 5, and γ-cyanopimelonitrile 7 with a recombinant plant nitrilase from Arabidopsis thaliana, expressed in E. coli, is described. Conversion rate and selectivity of the hydrolysis of dinitriles 1a-f to ω-cyanocarboxylic acids 2a-f depend on the chain length. The enzyme activity markedly increases from malononitrile (1a) to octanedinitrile (1f). The selectivity, however, does not correlate with the rates. Up to a chain length of 6 C-atoms, the cyanocarboxylic acid is the only product, even at complete conversion of the starting material. Pimelonitrile (1e) is hydrolyzed to the cyanocarboxylic acid 2e without formation of diacid (1%) up to 73% conversion. Glutaronitriles 5a-c were also hydrolyzed to the corresponding cyanobutanoic acids 6a-c with perfect selectivity. The nitrilase hydrolyzes exclusively the primary cyano group of 7 to give 3,5-dicyanoheptanoic acid (8a), whereby the selectivity is slightly reduced compared to the unsubstituted pimelonitrile (1e). If the hydrolysis is terminated at conversions ≤90%, pure 8a can be isolated in 72% yield (92% referred to conversion). After esterification of 8a to the methyl ester 8b, only the 5-cyano group but not the ester function was hydrolyzed enzymatically to give cyanoheptanedioic acid monoester (10).
- Effenberger,Osswald
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p. 1866 - 1872
(2007/10/03)
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- NaY zeolite: A useful catalyst for nitrile hydrolysis
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The NaY zeolite catalysed hydrolysis of nitriles to primary amides is reported. It is found that aryl nitriles with strong electron-withdrawing substituents and cyanopyridines are readily hydrolysed in the water suspension, while aliphatic nitriles do not react.
- Milli?, Dragana R.,Opsenica, Dejan M.,Adnadevi?, Borivoje,?olaja, Bogdan A.
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p. 118 - 126
(2007/10/03)
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- Role of chloride in the oxidative decarboxylation of amino acids by chloramine-T
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Kinetics of oxidative decarhoxylation of amino acids by chloramine-T in the presence of chloride have been studied in aqueous perchloric acid over a wide range. The rate-[H+] plots show nearly bell-shaped profiles in the presence of added chloride. The rate-dependence in [CAT] changes from second order to first order as [H+] and [Cl-] are varied. The reactions generally show fractional order kinetics in [AA] and inverse dependence in [H+] except in the acid range 0.05-0.20 mol dm-3. Mechanisms consistent with the observed results are discussed. The rate-limiting steps have been identified and constants of these steps calculated. Activation parameters corresponding to these steps have also been computed. Validity of Taft equation has been tested. The study establishes the significant role of chloride in chloramine-T oxidations in acid medium. The chloride effect is more pronounced at high acid concentrations.
- Gowda, B. Thimme,Quine, S. Darlin,Krishna Kumar
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p. 413 - 420
(2007/10/03)
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- Chemoenzymic Production of Lactams from Aliphatic α,ω-Dinitriles
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Five- and six-membered ring lactams have been prepared by first converting an aliphatic α,ω-dinitrile to an ω-cyanocarboxylic acid ammonium salt, using a microbial cell catalyst having an aliphatic nitrilase activity (Acidovorax facilis 72W, ATCC 55746) or a combination of nitrile hydratase and amidase activities (Comamonas testosteroni 5-MGAM-4D, ATCC 55744). The ω-cyanocarboxylic acid ammonium salt was then directly converted to the corresponding lactam by hydrogenation in aqueous solution, without isolation of the intermediate ω-cyanocarboxylic acid or ω-aminocarboxylic acid. Only one of two possible lactam products was produced from α-alkyl-substituted α,ω-dinitriles, where the nitrilase of A. facilis 72W regioselectively hydrolyzed only the ω-cyano group to produce a single cyanocarboxylic acid ammonium salt in greater than 98% yield.
- Gavagan, John E.,Fager, Susan K.,Fallon, Robert D.,Folsom, Patrick W.,Herkes, Frank E.,Eisenberg, Amy,Hann, Eugenia C.,DiCosimo, Robert
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p. 4792 - 4801
(2007/10/03)
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- Rationalisation of the regioselective hydrolysis of aliphatic dinitriles with Rhodococcus rhodochrous AJ270
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Aliphatic dinitriles undergo regioselective hydrolysis with the title organism to give monoacids with up to four methylenes between the nitrile functions (optimally 2-3) or when either an oxygen is placed β, γ or δ to the nitrile (δ-placement being optimal) or β or γ (optimally γ) but not δ sulfur substituents are present; nitrogen substituents appear to behave as for oxygen but suffer a steric limitation of the size of the nitrogen substituent.
- Meth-Cohn, Otto,Wang, Mei-Xiang
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p. 1041 - 1042
(2007/10/03)
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- Regioselective biotransformations of dinitriles using Rhodococcus sp. AJ270
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A variety of dinitriles have been hydrolysed selectively under very mild conditions using Rhodococcus sp. AJ270. Aliphatic dinitriles NC[CH2]nCN 1 undergo regioselective hydrolysis to give the mono acids 2 with up to 4 methylenes between the nitrile functions while those with n > 4 give the diacids 3 in good yield. Dinitriles NC[CH2]nX[CH2]nCN 4 bearing an ether or sulfide linkage are efficiently transformed into the mono acids 5 when an oxygen is placed β, γ or δ to the cyano group or a β- or γ-sulfur is present. Hydrolysis of N,N-bis(2-cyanoethyl)anilines 4h-j takes place slowly affording exclusively the monoacids 5h-j while the monocyano amides 5o-p are obtained as the sole isolable product from rapid hydrolysis of the corresponding N,N-bis(2-cyanomethyl)butylamine 4o and N,N-bis(3-cyanopropyl)butylamine 4p. Higher homologues of arylimino- and butylimino-dinitriles are inert to enzymatic hydrolysis. A variety of other aliphatic dinitriles have been converted readily into mono acids in good to excellent yields except for o-phenylenediacetonitrile which gives o-phenylenediacetamide as the major product. The title organism also effects the hydrolysis of aromatic dinitriles with regiocontrol such as m- and p-dicyanobenzenes, but nct the ortho-substituted analogue. The scope and limitations of this enzymatic process have been systematically studied and the mechanism of regioselective hydrolysis has been discussed in terms of a chelation-deactivation effect.
- Meth-Cohn, Otto,Wang, Mei-Xiang
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p. 3197 - 3204
(2007/10/03)
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- SELECTIVE HYDROLYSIS OF NITRILES UNDER MILD CONDITIONS BY AN ENZYME
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A wide range of aromatic/aliphatic nitriles and dinitriles have been selcetively hydrolysed using a commercially available enzyme preparation from a Rhodococcuc sp.
- Cohen, Mark A.,Sawden, Janette,Turner, Nicholas J.
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p. 7223 - 7226
(2007/10/02)
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- Chloride Ion-catalysed Oxidation of Arginine, Threonine, and Glutamic Acid by 1-Chlorobenzotriazole: a Kinetic and Mechanistic Study
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The kinetics of oxidation of arginine, threonine, and glutamic acid by 1-chlorobenzotriazole (CBT) were studied in HClO4 with Cl(1-) ion as a catalyst at 303 deg K.The results are compared with those obtained with chlorine water and HOCl as oxidant.The reactions followed identical kinetics, being first-order each in and and fractional order in . ions retard the reaction (inverse fractional order).The solvent isotope effect was studied.Variation of ionic strength and addition of the reaction product had no effect on the rate.A decrease in the dielectric constant of the medium increased the rate.Activation parameters were evaluated.A suitable mechanism consistent with the observed kinetics is proposed.
- Hiremath, Rajashekhar C.,Mayanna, Sanabaghatta M.,Venkatasubramanian, Nagaswami
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p. 1569 - 1574
(2007/10/02)
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- Chloraminometric Reactions: Kinetics and Mechanisms of Oxidations of Amino-acids by Sodium N-Chlorotoluene-p-sulphonamide in Acid and Alkaline Media
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Available data on the kinetics of oxidations of amino-acids by sodium N-chloro toluene-p-sulphonamide (chloramine T) in acid and alkaline media have been critically examined.General mechanisms have been proposed for both acid and alkaline medium oxidations.The oxidation process in acid media has been shown to proceed via two paths, one involving the direct interaction of N-chlorotoluene-p-sulphonamide (RNHCl) with the neutral amino-acid in a slow step leading to the formation of the monochloroamino-acid which subsequently interacts with another molecule of RNHCl, in a fast step, to give the NN-dichloroamino-acid which in turn undergoes molecular rearrangement and elimination to yield the products, and the other involving the interaction of Cl2 or H2OCl(1+), produced from the disproportionation of RNHCl in the presence or absence of Cl(1-), with the substrate to give the products.In the alkaline medium mechanisms involving the interaction of RNHCl, HOCl, RNCl(1-), and OCl(1-) with the substrate are proposed.The mechanisms proposed and the derived rate lows are consistent with the observed kinetics.The rate constants predicted by the derived rate laws, as the concentrations of substrate and Cl(1-) ion change, are in excellent agreement with the observed rate constants thus further verifying the rate laws and hence the proposed mechanisms.
- Gowda, Basavalinganadoddy Thimme,Mahadevappa, Darndinasivara S.
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p. 323 - 334
(2007/10/02)
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