- Probing the enantioselectivity of a diverse group of purified cobalt-centred nitrile hydratases
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In this study a diverse range of purified cobalt containing nitrile hydratases (NHases, EC 4.2.1.84) from Rhodopseudomonas palustris HaA2 (HaA2), Rhodopseudomonas palustris CGA009 (009), Sinorhizobium meliloti 1021 (1021), and Nitriliruptor alkaliphilus (iso2), were screened for the first time for their enantioselectivity towards a broad range of chiral nitriles. Enantiomeric ratios of >100 were found for the NHases from HaA2 and CGA009 on 2-phenylpropionitrile. In contrast, the Fe-containing NHase from the well-characterized Rhodococcus erythropolis AJ270 (AJ270) was practically aselective with a range of different α-phenylacetonitriles. In general, at least one bulky group in close proximity to the α-position of the chiral nitriles seemed to be necessary for enantioselectivity with all NHases tested. Nitrile groups attached to a quaternary carbon atom were only reluctantly accepted and showed no selectivity. Enantiomeric ratios of 80 and >100 for AJ270 and iso2, respectively, were found for the pharmaceutical intermediate naproxennitrile, and 3-(1-cyanoethyl)benzoic acid was hydrated to the corresponding amide by iso2 with an enantiomeric ratio of >100.
- Van Pelt,Zhang,Otten,Holt,Sorokin,Van Rantwijk,Black,Perry,Sheldon
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experimental part
p. 3011 - 3019
(2011/06/17)
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- An unexpected synthesis of ketene monothioacetals
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Some dithiocarbonates (xanthates) can be converted into ketene monothioacetals through extrusion of sulfur upon treatment with base and an alkylating agent. The Royal Society of Chemistry.
- Fabre, Stephanie,Vila, Xavier,Zard, Samir Z.
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p. 4964 - 4966
(2007/10/03)
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- α-chloronitriles production method
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The invention relates to a process for the preparation of α-chloronitriles by reaction of cyanohydrins of aldehydes or ketones with phosgene using a phosphine oxide as catalyst.
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Page column 4
(2008/06/13)
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- Indium-mediated reductive dehalogenation of α-halocarbonyl compounds in water
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Reactions of various α-halocarbonyl compounds 1 with indium in the presence of a catalytic amount of sodium dodecyl sulfate in water were performed to afford the corresponding parent carbonyl compounds 2 in excellent yields. The Royal Society of Chemistry 2000.
- Park, Leeyoung,Keum, Gyochang,Kang, Soon Bang,Kim, Kwan Soo,Kim, Youseung
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p. 4462 - 4463
(2007/10/03)
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- The reduction of α,β-unsaturated nitriles and α-halonitriles with sodium hydrogen telluride
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Sodium hydrogen telluride reacts chemoselectively with α,β- unsaturated nitriles and α-halonitriles linked to aromatic and aliphatic substituents to corresponding saturated nitriles with good yields.
- Blay, Gonzalo,Cardona, Luz,Garcia, Begona,Lahoz, Luisa,Pedro, Jose R.
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p. 8611 - 8618
(2007/10/03)
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- A convenient synthesis of (S)-2-azidonitriles, (S)-2-aminonitriles and (S)-1,2-diamines
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(S)-2-Azidonitriles (S)-4 are easily accessible from (R)-2-(sulfonyloxy)nitriles (R)-2 by nucleophilic substitution with alkali azides 3 under complete inversion of configuration. The azidonitriles (S)-4 can be converted by catalytic hydrogenation into (S)-2-aminonitriles (S)-8 and by hydrogenation using LiAlH4 into (S)-1,2-diaminoalkanes (S)-9, respectively, both, (S)-8 and (S)-9, isolated as hydrochlorides. Hydrolysis of the aminonitrile hydrochlorides (S)-8·HCl in a saturated solution of HCl in alcohol gives (S)-2-amino carboxamide hydrochlorides (S)-10·HCl with enantiomeric excesses >99% after recrystallization.
- Effenberger,Kremser, Andreas,Stelzer, Uwe
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p. 607 - 618
(2007/10/03)
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- Kinetic Resolution of Racemic Aldehydes by Enantioselective Alkylation
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Various types of racemic aldehydes were kinetically resolved with diethylzinc in the presence of a catalytic amount of a chiral β-amino alcohol.Kinetic resolution of racemic chloro(phenyl)acetaldehyde gave an optically active form as an unchanged substrate, which could be converted into styrene oxide in high optical purity (97.5percent ee).
- Hayashi, Masahiko,Miwata, Hiroshi,Oguni, Nobuki
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p. 1167 - 1171
(2007/10/02)
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- Oxidation using Phase Transfer Catalyst - A Mechanistic Study
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Oxidation of benzyl alcohol and benzyl cyanide by sodium hypochlorite under phase transfer conditions involves initial chlorination at the benzylic carbon.Since no reaction takes place in the absence of a phase transfer catalyst, it clearly indicates involvement of an ionic species in the organic phase.
- Mathur, S. N.,Rao, S. Nagabushan,Bhalerao, U. T.
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- On the Preparation of Acyl Cyanides from Aldehydes
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The O-silylated cyanohydrins 3 prepared from the aldehydes 1 with trimethylsilyl cyanide are oxidized photochemically or thermally with N-bromosuccinimide to afford the acyl cyanides 4a-n.Scope and limitations of the procedure are discussed.
- Haerle, Helmut,Jochims, Johannes C.
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p. 1400 - 1412
(2007/10/02)
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- ONE-POT SYNTHESIS OF α-CHLORONITRILES FROM ARYLCARBONYL COMPOUNDS
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α-Chloronitriles are prepared by the reaction of arylcarbonyl compounds and trimethylsilyl cyanide with a stoichiometric amount of titanium tetrachloride in good yields.
- Kiyooka, Syun-ichi,Fujiyama, Ryoji,Kawaguchi, Katsuhiko
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p. 1979 - 1980
(2007/10/02)
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