- Studies on phosphoroheterocycle chemistry III: An unusual way to 1,3,2-thiazaphospholidine-4-thione 2-sulfide derivatives
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An unusual but efficient method for the synthesis of phosphoroheterocycles, 1,3,2-thiazaphospholidine-4-thione 2-sulfide derivatives, by the reaction of Lawesson's reagent with a variety of α-hydroxy nitriles has been developed. The possible mechanism of the reaction is proposed to involve thiation of hydroxy group in a first step, sequential addition of P-SH to the nitrile and rearrangement resulting in the title phosphoroheterocycles. The preliminary bioassays show that these heterocyclic compounds have herbicidal properties.
- Deng, ShengLou,Chen, RuYu
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- Direct C(sp3)-H Cyanation Enabled by a Highly Active Decatungstate Photocatalyst
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A highly efficient, direct C(sp3)-H cyanation was developed under mild photocatalytic conditions. The method enabled the direct cyanation of various C(sp3)-H substrates with excellent functional group tolerance. Notably, complex natural products and bioactive compounds were efficiently cyanated.
- Kim, Kunsoon,Lee, Seulchan,Hong, Soon Hyeok
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supporting information
p. 5501 - 5505
(2021/07/26)
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- Enantioselective Synthesis of α-Thiocarboxylic Acids by Nitrilase Biocatalysed Dynamic Kinetic Resolution of α-Thionitriles
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The enantioselective synthesis of α-thiocarboxylic acids by biocatalytic dynamic kinetic resolution (DKR) of nitrile precursors exploiting nitrilase enzymes is described. A panel of 35 nitrilase biocatalysts were screened and enzymes Nit27 and Nit34 were found to catalyse the DKR of racemic α-thionitriles under mild conditions, affording the corresponding carboxylic acids with high conversions and good-to-excellent ee. The ammonia produced in situ during the biocatalytic transformation favours the racemization of the nitrile enantiomers and, in turn, the DKR without the need of any external additive base.
- Lauder, Kate,Anselmi, Silvia,Finnigan, James D.,Qi, Yuyin,Charnock, Simon J.,Castagnolo, Daniele
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supporting information
p. 10422 - 10426
(2020/07/24)
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- A 2 - hydroxy dissidents calcium synthetic method
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The invention discloses a 2 - hydroxy dissidents calcium synthetic method: to different pentanals, sodium bisulfite, sodium cyanide as raw material through nucleophilic addition reaction in the synthesis of 2 - hydroxy different fifth heavenly stem nitrile, then in acidic conditions by the hydrolysis reaction of the 2 - hydroxy dissidents acid, the final calcium salt exchange reaction 2 - hydroxy dissidents calcium, then refined to get the pure product 2 - hydroxy dissidents acid calcium, refined pure product purity as high as 99.7%, three-step [...] yield is up to 80% or more. The method has the production cycle is short, simple and convenient operation, is suitable for industrial production.
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Paragraph 0020-0022; 0030-0032; 0039-0041
(2019/07/05)
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- Catalytic asymmetric synthesis of secondary nitriles via stereoconvergent negishi arylations and alkenylations of racemic α-bromonitriles
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The first method for the stereoconvergent cross-coupling of racemic α-halonitriles is described, specifically, nickel-catalyzed Negishi arylations and alkenylations that furnish an array of enantioenriched α-arylnitriles and allylic nitriles, respectively. Noteworthy features of this investigation include: the highly enantioselective synthesis of α-alkyl-α-aryl nitriles that bear secondary α-alkyl substituents; the first examples of the use of alkenylzinc reagents in stereoconvergent Negishi reactions of alkyl electrophiles; demonstration of the utility of a new family of ligands for asymmetric Negishi cross-couplings (a bidentate bis(oxazoline), rather than a tridentate pybox); in the case of arylzinc reagents, carbon-carbon bond formation at a remarkably low temperature (-78 °C), the lowest reported to date for an enantioselective cross-coupling of an alkyl electrophile; a mechanistic dichotomy between Negishi reactions of an unactivated versus an activated secondary alkyl bromide.
- Choi, Junwon,Fu, Gregory C.
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supporting information; experimental part
p. 9102 - 9105
(2012/07/13)
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- Unsymmetric salen ligands bearing a Lewis base: Intramolecularly cooperative catalysis for cyanosilylation of aldehydes
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A series of unsymmetric salen ligands derived from 1,2-diaminocyclohexane bearing an appended Lewis base on the three-position of one aromatic ring were synthesized by the reaction of various functional salicyaldehydes with the condensation product of 1,2-diaminocyclohexane mono(hydrogen chloride) and 3,5-di-tert-butylsalicylaldehyde. These ligands in conjunction with Ti(O iPr)4 exhibited excellent activity in catalyzing the cyanosilylation of aldehydes with trimethylsilyl cyanide (TMSCN) at mild conditions. The highest activity was observed in the catalyst system with regard to the salen ligand bearing a diethylamino group, which proved to be active even at a high [aldehyde]/[catalyst] ratio up to 50000. In a low catalyst loading of 0.05 mol%, the quantitative conversion of benzaldehyde to the corresponding cyanosilylation product was found within 10 min. at ambient temperature. An intramolecularly cooperative catalysis was proposed wherein the central metal Ti(iv) is suggested to play a role of Lewis acid to activate aldehydes while the appended Lewis base to activate TMSCN.
- Wen, Ye-Qian,Ren, Wei-Min,Lu, Xiao-Bing
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supporting information; experimental part
p. 6323 - 6330
(2011/10/09)
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- Pyrazolotriazines
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Compounds of a certain formula I, in which R1, R2, A, R4, B, R5 and R6 have the meanings indicated in the description, are effective compounds with anti-proliferative and/or apoptosis inducing activity.
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Page/Page column 45
(2009/07/10)
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- Synthesis of aliphatic (S)-α-hydroxycarboxylic amides using a one-pot bienzymatic cascade of immobilised oxynitrilase and nitrile hydratase
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A one-pot bienzymatic cascade combining a hydroxynitrile lyase (Manihot esculenta, E.C. 4.1.2.10) and a nitrile hydratase (Nitriliruptor alkaliphilus, E.C. 4.2.1.84) for the synthesis of enantiopure aliphatic α- hydroxycarboxylic amides from aldehydes is described. Both enzymes were immobilised as cross-linked enzyme aggregates (CLEAs). Stability tests show that the nitrile hydratase CLEAs are sensitive to water-immiscible organic solvents as well as to aldehydes and hydrogen cyanide (HCN), but are remarkably stable and show useful activity in acidic aqueous environments of pH 4-5. The cascade reactions are consequently carried out by using a portionwise feed of HCN and moderate concentrations of aldehyde in acidic aqueous buffer to suppress the uncatalysed hydrocyanation background reaction. After optimisation, this method was used to synthesise five different kinds of aliphatic α- hydroxycarboxylic amides from the corresponding aldehydes with good yields and with enantiomeric purities comparable to those obtained for the α-hydroxynitriles in the microaqueous hydrocyanation using hydroxynitrile lyase and an excess of HCN.
- Van Pelt, Sander,Van Rantwijk, Fred,Sheldon, Roger A.
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experimental part
p. 397 - 404
(2009/12/01)
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- Stereospecific α-methallylation of hydroxyaldehydes by silatropic ene cyclisation
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We describe the thermal rearrangement of aldehydes bearing an α-(allyl- or crotylsilyl)oxy substituent. The transformations are best described mechanistically as intramolecular silatropic ene reactions based on stereoselectivity, kinetic and computed transition state data. The overall process constitutes a stereospecific (meth)allylation of α-hydroxyaldehydes, under neutral conditions, in which the hydroxyl protecting group is also the (meth)allylating agent.
- Robertson, Jeremy,Hall, Michael J.,Green, Stuart P.
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experimental part
p. 5541 - 5551
(2009/12/09)
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- Purification and characterization of a novel (R)-hydroxynitrile lyase from Eriobotrya japonica (Loquat)
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A hydroxynitrile lyase was isolated and purified to homogeneity from seeds of Eriobotrya japonica (loquat). The final yield, of 36% with 49-fold purification, was obtained by 30-80% (NH4)2SO4 fractionation and column chromatography on DEAE-Toyopearl and Concanavalin A Sepharose 4B, which suggested the presence of a carbohydrate side chain. The purified enzyme was a monomer with a molecular mass of 72 kDa as determined by gel filtration, and 62.3 kDa as determined by SDS-gel electrophoresis. The N-terminal sequence is reported. The enzyme was a flavoprotein containing FAD as a prosthetic group, and it exhibited a Km of 161 μM and a k cat/Km of 348 s-1 mM-1 for mandelonitrile. The optimum pH and temperature were pH 5.5 and 40°C respectively. The enzyme showed excellent stability with regard to pH and temperature. Metal ions were not required for its activity, while activity was significantly inhibited by CuSO4, HgCl2, AgNO3, FeCl3, β-mercaptoethanol, iodoacetic acid, phenylmethylsulfonylfluoride, and diethylpyrocarbonate. The specificity constant (kcat/Km) of the enzyme was investigated for the first time using various aldehydes as substrates. The enzyme was active toward aromatic and aliphatic aldehydes, and showed a preference for smaller substrates over bulky one.
- Ueatrongchit, Techawaree,Kayo, Ai,Komeda, Hidenobu,Asano, Yasuhisa,H-Kittikun, Aran
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p. 1513 - 1522
(2008/12/21)
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- An asymmetric, chemo-enzymatic synthesis of O-acetylcyanohydrins
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A one-pot chemo-enzymatic synthesis of highly enantiomerically enriched O-acetylcyanohydrins has been developed. The bimetallic (salen)titanium complex 1 is used to convert aldehydes into nonracemic (R)-O-acetylcyanohydrins with 61 to 93 % enantiomeric ex
- Belokon, Yuri N.,Blacker, A. John,Clutterbuck, Lisa A.,Hogg, David,North, Michael,Reeve, Christopher
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p. 4609 - 4617
(2007/10/03)
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- A new (R)-hydroxynitrile lyase from Prunus mume: Asymmetric synthesis of cyanohydrins
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A new hydroxynitrile lyase (HNL) was isolated from the seed of Japanese apricot (Prunus mume). The enzyme has similar properties with HNL isolated from other Prunus species and is FAD containing enzyme. It accepts a large number of unnatural substrates (benzaldehyde and its variant) for the addition of HCN to produce the corresponding cyanohydrins in excellent optical and chemical yields. A new HPLC based enantioselective assay technique was developed for the enzyme, which promotes the addition of KCN to benzaldehyde in a buffered solution (pH=4.5).
- Nanda, Samik,Kato, Yasuo,Asano, Yasuhisa
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p. 10908 - 10916
(2007/10/03)
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- O-Protected 3-hydroxy-oxazolidin-2,4-diones: Novel precursors in the synthesis of α-hydroxyhydroxamic acids
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O-Protected 3-hydroxyoxazolidin-2,4-diones have been prepared in a novel one-pot reaction by subsequent treatment of cyanohydrins with 1,1′-carbonyldiimidazole and O-protected hydroxylamines followed by acidic hydrolysis of the intermediate 4-imino-oxazolidin-2-ones. Decarbonylation of O-protected 3-hydroxyoxazolidin-2,4-diones by catalytic amounts of sodium methoxide, lithium hydroxide, sodium carbonate and caesium carbonate in methanol afforded O-protected α-hydroxyhydroxamic acids in excellent yields. Their deprotection provided a series of novel α-hydroxyhydroxamic acids.
- Kurz, Thomas,Widyan, Khalid
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p. 2023 - 2027
(2007/10/03)
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- Indium trifluoride - A Lewis acid catalyst for the addition of TMSCN to aldehydes in water
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Indium trifluoride promoted chemoselective additions of TMSCN to various aldehydes in water gave the respective cyanohydrins in good yields.
- Loh, Teck-Peng,Xu, Kai-Chen,Ho, Diana Sook-Chiang,Sim, Keng-Yeow
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p. 369 - 370
(2007/10/03)
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- Enantioselectivity of Pseudomonas cepacia lipase for the acetylation of 2-hydroxy carboxylic acid esters+
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Structurally different ethyl or methyl 2-hydroxy carboxylates were resolved by Pseudomonas cepacia lipase-catalysed acetylations with vinyl acetate in diethylether. One type of the alcoholic substrates (2-hydroxy-2-arylacetates and 2-hydroxy-3-arylpropinates) contained a HO-group at the stereocentre. These compounds were resolved with high enantioselectivity (ee 91 → 99) at ca. 50% conversion. The other alcoholic substrates ((threo-2-hydroxy-3-methylbutyrate and threo- or erythro-2-hydroxy-3-aryl-3-arylthio(or aryloxy)propionates) with two stereocentres generally resulted in enantiopure products and the reactions stopped at 50 % conversion.
- Sundholm, Oskari,Kanerva, Liisa T.
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p. 625 - 640
(2007/10/03)
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- A General Synthesis of 3,5-Dihalo-2H-1,4-oxazin-2-ones from Cyanohydrins
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In a novel approach starting from O-trimethylsilyl protected or unprotected cyanohydrins and oxalyl chloride or bromide, a series of unknown 6-substituted 3,5-dihalo-2H-1,4-oxazin-2-ones were prepared.The method was shown to be efficient for various types of cyanohydrins; however cyclization was not obtained with cyanohydrins containing bulky substituents, electron-rich aryl or heteroaryl groups.A mechanism is proposed.
- Meerpoel, Lieven,Hoornaert, Georges
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p. 905 - 908
(2007/10/02)
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- Enzymatic Preparation of Optically Active Cyanohydrin Acetates
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A series of cyanohydrin acetates (1)-(47) of widely varying structures, potential chiral building blocks for numerous synthetic applications, has been prepared in good chemical and often high optical yields by enzymatic hydrolysis of their racemic acetates in the presence of an ester hydrolase from Pseudomonas sp.
- Almsick, Andreas van,Buddrus, Joachim,Hoenicke-Schmidt, Petra,Laumen, Kurt,Schneider, Manfred P.
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p. 1391 - 1393
(2007/10/02)
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- Biosynthesis of Diisocyanoadociane, a Novel Diterpene from the Marine Sponge Amphimedon sp. Crystal Structure of a Monoamide Derivative
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Sodium cyanide is efficiently incorporated into diisocyanoadociane , the major metabolite of the haplosclerid sponge Amphimedon sp.It is established by stepwise chemical degradation that the radiolabel is associated with the two isocyanide carbons.Zinccyanide and isobutyraldehydecyanohydrin are effective precursor alternatives to sodium cyanide and more suitable for use in stable isotope study.Attempts to demonstrate an amino acid origin of the cyanide utilised by Amphimedon sp. include tracer studies with alanine, glycine, arginine; none of these precursors were used for isocyanide synthesis.Single X-ray crystallographic structure analysis of p-bromobenzamide degradation product (17) established that the absolute configuration for diisocyanoadociane is (1R,2R,3aS,5S,6R,8S,8aS,10aS,10bS,10cS).
- Fookes, Christopher J. R.,Garson, Mary J.,MacLeod, John K.,Skelton, Brian W.,White, Allan H.
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p. 1003 - 1012
(2007/10/02)
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- LANTHANIDES AS LEWIS-ACID CATALYSTS IN ALDOL ADDITION, CYANOHYDRIN-FORMING AND OXIRANE RING OPENING REACTIONS
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Lanthanide trichlorides (Ln = La,Ce,Sm) and Eu(fod)3 catalyze the aldol addition of silyl enol ethers to aldehydes, the addition of trimethylsilyl cyanide to aldehydes and ketones as well as the synthesis of β-cyanosilyl ethers.
- Vougioukas, Angelos E.,Kagan, Henri B.
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p. 5513 - 5516
(2007/10/02)
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- Process for preparation of cyanohydrins
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This invention relates to the discovery that high yields of excellent quality cyanohydrins can be prepared by reacting certain carbonyl compounds in a solution of metallic cyanide and hydrochloric acid.
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- Mechanism of Hydrolysis of N-(1-Aminoalkyl) Amides
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Many of the title compounds (structure 1) are remarkably stable to hydrolysis and can be isolated and characterized.The pH-rate profile for hydrolysis of the title compounds involves plateaus in the acid and base region, with the rate of hydrolysis in the basic region somewhat faster.The compounds hydrolyze to amides, aldehydes, and ammonia; the intermediacy of an imine in the basic region is demonstrated by its trapping with added CN-.An optically active derivative of 1 hydrolyzes and loses optical activity at about the same rate in both the acidic and basic regions of pH.The reaction is characterized in basic solution by highly positive activation entropies, and alkylation of the amino nitrogen increases the rate significantly.The hydrolysis reaction shows no detectable buffer catalysis at any pH studied.The hydrolysis reaction is very sensitive to the amide leaving group; electron-withdrawing substituents on the amide portion of 1 substantially increase the rate of hydrolysis.The mechanism of hydrolysis in basic solution seems to be best described as a unimolecular solvolysis with an amide anion as a leaving group (Scheme I).In acidic solution the most likely mechanism of hydrolysis (Scheme II) appears to involve the expulsion of an amide enol (imidic acid).The implications of these findings are discussed for situation in which compounds of type 1 have found utility.
- Loudon, G. Marc,Almond, Merrick R.,Jacob, James N.
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p. 4508 - 4515
(2007/10/02)
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