- Ketoreductase catalyzed stereoselective bioreduction of α-nitro ketones
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We report here the stereoselective bioreduction of α-nitro ketones catalyzed by ketoreductases (KREDs) with publicly known sequences. YGL039w and RasADH/SyADH were able to reduce 23 class I substrates (1-aryl-2-nitro-1-ethanone (1)) and ten class II substrates (1-aryloxy-3-nitro-2-propanone (4)) to furnish both enantiomers of the corresponding β-nitro alcohols, with good-to-excellent conversions (up to >99%) and enantioselectivities (up to >99% ee) being achieved in most cases. To the best of our knowledge, KRED-mediated reduction of class II α-nitro ketones (1-aryloxy-3-nitro-2-propanone (4)) is unprecedented. Select β-nitro alcohols, including the synthetic intermediates of bioactive molecules (R)-tembamide, (S)-tembamide, (S)-moprolol, (S)-toliprolol and (S)-propanolol, were stereoselectively synthesized in preparative scale with 42% to 90% isolated yields, showcasing the practical potential of our developed system in organic synthesis. Finally, the advantage of using KREDs with known sequence was demonstrated by whole-cell catalysis, in which β-nitro alcohol (R)-2k, the key synthetic intermediate of hypoglycemic natural product (R)-tembamide, was produced in a space-time yield of 178 g L?1 d?1 as well as 95% ee by employing the whole cells of a recombinant E. coli strain coexpressing RasADH and glucose dehydrogenase as the biocatalyst.
- Wang, Zexu,Wu, Xiaofan,Li, Zhining,Huang, Zedu,Chen, Fener
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p. 3575 - 3580
(2019/04/14)
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- Organocatalytic asymmetric Michael/hemiacetalization/acyl transfer reaction of α-nitroketones with o-hydroxycinnamaldehydes: Synthesis of 2,4-disubstituted chromans
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An organocatalytic asymmetric cascade Michael/hemiketalization/acyl transfer reaction between o-hydroxycinnamaldehydes and α-nitroketones is developed. Prolinol TMS ether catalyst in combination with benzoic acid was found to be the most effective for this reaction which proceeds through an equilibrium of lactols to provide a single diastereomer of enantiopure 2,4-disubstituted chromans.
- Maity, Rajendra,Pan, Subhas Chandra
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p. 1598 - 1608
(2018/03/08)
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- Organocatalytic Asymmetric Domino Michael/Acyl Transfer Reaction Between α-Nitroketones and in situ-Generated ortho-Quinone Methides: Route to 2-(1-Arylethyl)phenols
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An organocatalytic asymmetric domino Michael/acyl transfer reaction between α-nitroketones and o-quinone methides is disclosed. o-Quinone methides are generated in situ from 2-sulfonylmethylphenols in basic medium. With 10 mol% of bifunctional squaramide catalyst, high yields and excellent enantioselectivities are achieved for a variety of O-acyl 2-(1-arylethyl)phenols under mild reaction condition. (Figure presented.).
- Gharui, Chandan,Behera, Debasmita,Pan, Subhas Chandra
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p. 4502 - 4508
(2018/11/10)
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- Unexpected C-C bond cleavage of α-nitroketone in the presence of TsNBr2: A new pathway for C-N bond formation
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A new catalyst-free protocol for C-N bond formation via the cleavage of α-nitroketone has been developed. When α-nitroketones are treated with TsNBr2 in the presence of potassium carbonate, unexpected cleavage of C(O)-CHNO2 bond of α-nitroketone was observed followed by the formation of corresponding amide. Various nitroketones could be converted to corresponding amide using this procedure.
- Sarma, Manas Jyoti,Phukan, Prodeep
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supporting information
p. 257 - 262
(2016/03/09)
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- Formation of new C-O and C-N bonds via base promoted Csp2-Csp3 bond cleavage of α-nitro ketone
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A catalyst free protocol has been developed for nucleophilic Csp2-Csp3 bond cleavage of α-nitroketone in the presence of potassium carbonate to create new C-O and C-N bonds. A series of different substituted α-nitroketones could be selectively cleaved and converted into corresponding esters and tosylamides in the presence of alcohols and bromamine-T, respectively.
- Sarma, Manas Jyoti,Borah, Arun Jyoti,Rajbongshi, Kamal Krishna,Phukan, Prodeep
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supporting information
p. 7008 - 7011
(2015/11/27)
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- Palladium-catalysed carbonylative α-arylation of nitromethane
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A simple and mild Pd-catalysed carbonylative α-arylation of nitromethane has been realised providing access to α-nitro aryl ketones from an array of aryl and heteroaryl iodides. The methodology requires only a mild base and uses the convenient solid CO re
- Lian, Zhong,Friis, Stig D.,Skrydstrup, Troels
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supporting information
p. 3600 - 3603
(2015/04/13)
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- Iridium diamine catalyst for the asymmetric transfer hydrogenation of ketones
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A simple and very efficient chiral aqua iridium(III) diamine complex leads to excellent enantioselectivities in the asymmetric transfer hydrogenation of various α-cyano and α-nitro ketones. The catalyst provides the ortho-substituted aromatic alcohols with especially high ee values. The diamine ligands can be used directly as chiral ligands; conversion into the corresponding sulfamide is not necessary.
- Vazquez-Villa, Henar,Reber, Stefan,Ariger, Martin A.,Carreira, Erick M.
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p. 8979 - 8981
(2011/11/30)
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- Transfer hydrogenation in water: Enantioselective, catalytic reduction of α-cyano and α-nitro substituted acetophenones
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Catalytic reduction of α-substituted acetophenones under conditions involving asymmetric transfer hydrogenation in water is described. The reaction is conducted in water and open to air, and formic acid is used as reductant.
- Soltani, Omid,Ariger, Martin A.,Vazquez-Villa, Henar,Carreira, Erick M.
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supporting information; experimental part
p. 2893 - 2895
(2010/09/09)
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- Indium-mediated one-pot synthesis of benzoxazoles or oxazoles from 2-nitrophenols or 1-aryl-2-nitroethanones
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One-pot reduction-triggered heterocyclizations from 2-nitrophenols to benzoxazoles and from 1-aryl-2-nitroethanones to oxazoles were investigated. In the presence of indium/AcOH in benzene at reflux, 2-nitrophenols and R-C(OMe)3 (R=H, Me, Ph) produced excellent yields of corresponding benzoxazoles within an hour. Similarly, 1-aryl-2-nitroethanones and Ph-C(OMe)3 in the presence of indium/AcOH in acetonitrile transformed into the corresponding oxazoles with good yields.
- Lee, Jung June,Kim, Jihye,Jun, Young Moo,Lee, Byung Min,Kim, Byeong Hyo
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experimental part
p. 8821 - 8831
(2009/12/26)
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- A New Method for the Preparation of α-Nitroacetophenones
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Treatment of readily available substituted β-nitrostyrenes with tert-butyl hydroperoxide and butyllithium gives synthetically useful α-nitroacetophenones in good yield.
- Ashwell, Mark A.,Jackson, Richard F. W.
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p. 229 - 231
(2007/10/02)
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