- Efficient aerobic oxidation of alcohols using magnetically recoverable catalysts
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A simple, highly efficient and mild catalytic aerobic oxidation of alcohol, in particularly benzoin was studied using iron oxide nanoparticles as a reusable catalyst. Moreover, benzyl was synthesized in large scale using inexpensive, readily available and
- Shaikh, Melad,Satanami, Mansingh,Ranganath, Kalluri V.S.
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- Efficient Synthesis of α-Ketothioamides From α-Nitroketones, Amines or DMF and Elemental Sulfur Under Oxidant-Free Conditions
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We have developed a practical, general protocol for denitration of readily available α-nitroketones with sulfur and amines to access a broad range of α-ketothioamides under mild conditions. Such a reaction proceeds under metal-, oxidant-, and catalyst-free conditions to provide synthetically useful α-ketothioamides. Furthermore, the mild reaction conditions tolerate a wide range of substrates especially for the synthesis of aliphatic α-ketothioamides which are rarely reported.
- Zhang, Zhenlei,Yang, Jiusi,Yu, Renjie,Wu, Kairui,Bu, Jiping,Li, Shaoke,Qian, Peng,Sheng, Liangquan
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p. 5209 - 5212
(2021/10/19)
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- Catalytic Enantioselective Synthesis of 3,4,5-Trisubstituted Isoxazoline N-Oxides and Regioselective Synthesis of 3,4,5-Trisubstituted Isoxazoles
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An efficient catalytic asymmetric synthesis of 3,4,5-trisubstituted isoxazoline N-oxides and regioselective synthesis of 3,4,5-trisubstituted isoxazoles has been described. α-Nitrocinnamates and α-nitrobenzophenones were utilized as Michael acceptors resp
- Sahoo, Subas Chandra,Pan, Subhas Chandra
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p. 1385 - 1389
(2019/01/09)
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- α-Nitro-α,β-Unsaturated Ketones: An Electrophilic Acyl Transfer Reagent in Catalytic Asymmetric Friedel-Crafts and Michael Reactions
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Herein, we introduce α-nitro-α,β-unsaturated ketones as efficient electrophilic acyl transfer reagents, and they were employed in Friedel-Crafts as well as in Michael reactions. The desired acyl transfer products of these reactions were obtained in high yields with high to excellent enantioselectivities with t-leucine-derived squaramide catalyst under mild reaction conditions. Few applications including a synthesis of the isoxazoline motif have been demonstrated.
- Parida, Chandrakanta,Maity, Rajendra,Chandra Sahoo, Subas,Chandra Pan, Subhas
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p. 6700 - 6704
(2019/09/07)
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- 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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- Copper-Mediated Reactions of Nitriles with Nitromethanes: Aza-Henry Reactions and Nitrile Hydrations
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In this study, the first aza-Henry reaction of nitriles with nitromethane in a CuI/Cs2CO3/DBU system is described. The process was conveniently and directly used for the synthesis of β-aminonitroalkenes 2a-x and tolerated aryl-, alkyl-, hetaryl-, alkenyl-, and alkynylnitriles. The resulting aminonitroalkenes 2 could be successfully transformed to the corresponding 2-nitroacetophenones, 2-amino-1-halonitroalkenes, 2-alkylaminonitroalkenes, or 3-nitropyridines. In the presence of H2O, the aza-Henry reaction turned the reaction path to the nitrile hydration to exclusively yield the amides 3a-s.
- Kuwabara, Jun,Sawada, Yoshiharu,Yoshimatsu, Mitsuhiro
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supporting information
p. 1130 - 1133
(2018/02/22)
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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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- Organocatalytic Asymmetric Michael/Hemiketalization/Retro-aldol Reaction of α-Nitroketones with Unsaturated Pyrazolones: Synthesis of 3-Acyloxy Pyrazoles
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An organocatalytic asymmetric cascade Michael/hemiketalization/retro-aldol reaction between unsaturated pyrazolones and α-nitroketones is described. A bifunctional thiourea catalyst was found to be efficient for this reaction. With 10 mol % of catalyst, high yields as well as excellent enantioselectivities are attained for a variety of 3-acyloxy pyrazoles under mild reaction conditions.
- Maity, Rajendra,Gharui, Chandan,Sil, Arun K.,Pan, Subhas Chandra
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p. 662 - 665
(2017/02/10)
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- Asymmetric Bioreduction of β-Acylaminonitroalkenes: Easy Access to Chiral Building Blocks with Two Vicinal Nitrogen-Containing Functional Groups
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The reduction of (Z)-β-acylaminonitroalkenes catalyzed by ene-reductases is described for the first time. The reaction occurs with a high conversion and excellent enantioselectivity and shows a wide substrate scope. The reduced products are valuable chiral synthons characterized by two vicinal nitrogen-containing functional groups that can be further modified by functional group inter-conversion thanks to the synthetic versatility of the nitro moiety. The chemo-enzymatic synthesis of (R)-N,N′-(1-phenylethane-1,2-diyl)diacetamide from easily accessible (Z)-N-(2-nitro-1-phenylvinyl)acetamide is herein reported as a representative application of this synthetic procedure.
- Brenna, Elisabetta,Crotti, Michele,Gatti, Francesco G.,Monti, Daniela,Parmeggiani, Fabio,Santangelo, Sara
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p. 2480 - 2487
(2017/07/12)
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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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- 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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- 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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- Remarkable Enhancement of Enantioselectivity in the Asymmetric Conjugate Addition of Dimethylzinc to (Z)-Nitroalkenes with a Catalytic [(MeCN)4Cu]PF6-Hoveyda Ligand Complex
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An enantioselective copper-catalyzed asymmetric conjugate addition of Me2Zn to (Z)-nitroalkenes led to the formation of all-carbon quaternary stereogenic centers with high stereoselectivity. The key features of the new method are the unprecedented use of [(MeCN)4Cu]PF6 in conjunction with the Hoveyda ligand L1 and the use of (Z)-nitroalkene substrates so that undesired nitroalkene isomerization is minimized and enantioselectivity is enhanced dramatically. We also describe a novel, practical, and highly (Z)-selective nitroalkene synthesis.
- Zeng, Xingzhong,Gao, Joe J.,Song, Jinhua J.,Ma, Shengli,Desrosiers, Jean-Nicolas,Mulder, Jason A.,Rodriguez, Sonia,Herbage, Melissa A.,Haddad, Nizar,Qu, Bo,Fandrick, Keith R.,Grinberg, Nelu,Lee, Heewon,Wei, Xudong,Yee, Nathan K.,Senanayake, Chris H.
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p. 12153 - 12157
(2016/02/23)
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- Efficient aerobic oxidation of alcohols using magnetically recoverable catalysts
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A simple, highly efficient and mild catalytic aerobic oxidation of alcohol, in particularly benzoin was studied using iron oxide nanoparticles as a reusable catalyst. Moreover, benzyl was synthesized in large scale using inexpensive, readily available and
- Shaikh, Melad,Satanami, Mansingh,Ranganath, Kalluri V.S.
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- Rhodium-catalyzed enantioselective hydrogenation of β-acylamino nitroolefins: A new approach to chiral β-amino nitroalkanes
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An efficient and highly enantioselective catalytic asymmetric hydrogenation of β-acylamino nitroolefins has been realized by using Rh-TangPhos as the catalyst. A series of β-amino nitroalkane products, which are versatile intermediates in organic synthesis, were obtained with high yield and good enantioselectivity.
- Zhou, Ming,Dong, Dejun,Zhu, Baolin,Geng, Huiling,Wang, Yan,Zhang, Xumu
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p. 5524 - 5527
(2013/11/19)
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- Highly enantioselective reduction of β-amino nitroolefins with a simple n-sulfinyl urea as bifunctional catalyst
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Simple but effective: A structurally simple N-sulfinyl urea was found to be a highly efficient bifunctional catalyst, which allows for the development of a novel pathway for the construction of chiral β-amino nitroalkanes through enantioselective reduction of β-amino nitroolefins by trichlorosilane. High yields and excellent enantioselectivities were obtained for a broad range of β-arylamino nitroolefin substrates (see scheme). Copyright
- Liu, Xiang-Wei,Yan, Yan,Wang, Yong-Qiang,Wang, Chao,Sun, Jian
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p. 9204 - 9207
(2012/08/27)
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- Asymmetric Rh(II)-catalyzed cyclopropanation of alkenes with diacceptor diazo compounds: P -methoxyphenyl ketone as a general stereoselectivity controlling group
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Different diacceptor diazo compounds bearing an α-PMP-ketone group were found to be effective carbene precursors for the highly stereoselective Rh2(S-TCPTTL)4-catalyzed cyclopropanation of alkenes (EWG = NO2, CN, CO2Me). The resulting products were readily transformed into a variety of biologically relevant enantiopure molecules, such as cyclopropane α- and β-amino acid derivatives. Different mechanistic studies carried out led to a rationale for the high diastereo- and enantioselectivity obtained, where the PMP-ketone moiety was found to play a critical role in the stereoinduction process. Additionally, the use of catalytic amounts of achiral Lewis bases to influence the enantioinduction of the reactions developed is documented.
- Lindsay, Vincent N. G.,Nicolas, Cyril,Charette, Andre B.
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p. 8972 - 8981
(2011/08/04)
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- Phenylation reaction of α-acylnitromethanes to give 1,2-diketone monooximes: Involvement of carbon electrophile at the position a to the nitro group
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The generality and the effects of substituents on phenylation reactions of α-acylnitromethanes catalyzed by trifluoromethanesulfonic acid have been studied. α-Aroylnitromethanes afforded benzil monooximes in good yield. In the case of aliphatic α-acylnitromethane, a similar phenylation reaction proceeded, but the yield of the phenylated 1,2-dione monooxime was low. These phenylation reactions represent examples of the generation of carbocation electrophiles at the α-position of a nitro group. Georg Thieme Verlag Stuttgart - New York.
- Takamoto, Mikihiro,Kurouchi, Hiroaki,Otani, Yuko,Ohwada, Tomohiko
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experimental part
p. 4129 - 4136
(2011/03/17)
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- Experimental evidence for the all-up reactive conformation of chiral rhodium(II) carboxylate catalysts: Enantioselective synthesis of cis-cyclopropane α-amino acids
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(Chemical Equation Presented) Useful empirical insights onto the enantioinduction process of chiral Rh(II)-carboxylate catalysts are described in the first catalytic asymmetric cyclopropanation of alkenes with α-nitro diazoacetophenones. X-ray, solution N
- Lindsay, Vincent N. G.,Lin, Wei,Charette, Andre B.
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supporting information; experimental part
p. 16383 - 16385
(2010/02/16)
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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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- Photochemical nitration by tetranitromethane. Part XLIII. Photolysis of some styrene derivatives with tetranitromethane: Mechanism of isoxazolidine formation
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The photochemical reaction of tetranitromethane in dichloromethane or acetonitrile with 4-methylstyrene (2a), styrene (2b), 4-chlorostyrene (2c), 3-chlorostyrene (2d) or 4-acetoxystyrene (2e) gives two stereoisomeric isoxazolidines, 2-(2′-nitro-1′-X-phenyl)ethoxy-3,3-dinitro-5-(X-phenyl)isoxazolidine (3 and 4, X = 4-Me, H, 4-Cl, 3-Cl or 4-AcO), a nitro ketone, nitromethyl X-phenyl ketone (5, X = 4-Me, H, 4-Cl, 3-Cl or 4-AcO) and a nitronic ester, 3-nitro-5-(X-phenyl)-2-isoxazoline N-oxide (6, X = 4-Me, H, 4-Cl or 4-AcO). In each case, the (RS,RS)-stereoisomer 4 is the major isoxazolidine formed. The first step of the reaction is the photogeneration of the triad [2.+ NO2 (NO2)3C-]. In the formation of isoxazolidines 3 and 4, and of the nitronic esters 6, the key intermediate is assumed to be the substituted aminoxyl, 3,3-dinitro-4-(X-phenyl)isoxazolidin-N-oxyl (8, X = 4-Me, H, 4-Cl, 3-Cl or 4-AcO) formed by reaction of the substituted styrene radical cation (2.+) with trinitromethanide ion followed by cyclization of the resulting carbon radical 7. Loss of nitrogen dioxide from 8 gives nitronic esters 6, and trapping of the l-(X-phenyl)-2-nitroethyl radical, formed by addition of NO2 at the β-carbon of 2, by aminoxyl 8, gives the isoxazolidines 3 and 4 directly. Acta Chemica Scandinavica 1998.
- Eberson, Lennart,Hartshorn, Michael P.,Persson, Ola
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p. 751 - 760
(2007/10/03)
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- Potential GABAB Receptor Antagonists. VII. The Synthesis of 2-(4-Chlorophenyl)-3-nitropropan-1-amine and Related Analogues of Baclofen
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3-Nitro-2-phenylpropan-1-amine and 2-(4-chlorophenyl)-3-nitropropan-1-amine have been synthesized by the addition of nitrous acid to the corresponding trifluoroacetylaminomethylstyrenes followed by reduction of the double bond with sodium borohydride.A more general and efficient route involves the Michael addition of nitroalkane anions to methyl cinnamates followed by Curtius degradation of the corresponding acids. 2-(4-Chlorophenyl)-3-nitropropan-1-amine is a specific agonist of GABA and the GABAB receptor, with about half the activity of racemic baclofen at the isolated guinea pig ileum.Methylation or dimethylation at C3 decreases activity markedly.
- Abbenante, Giovanni,Hughes, Robert,Prager, Rolf H.
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p. 1441 - 1452
(2007/10/02)
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- Photochemistry of Charge Transfer Complexes of Styrene Derivatives with Tetranitromethane. X-Ray Crystal Structure of a Novel Dimeric Adduct from p-Methylstyrene
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Styrene and its derivatives form coloured charge transfer complexes with tetranitromethane as the acceptor.These complexes are stable in acetonitrile under neutral conditions in the dark for several days.Photochemistry of these complexes was found to be highly dependent on the structure and substituent effects on the styrene.The structure of the dimeric adduct 2b from p-methylstyrene is determined by X-ray crystallography and it clearly establishes the ambident reactivity of the trinitromethide anion to act as an oxygen nucleophile in the present case, which is in contrast to its well known reactivity as a carbon nucleophile in the previously reported adducts from other aromatic substrates.
- Mathew, Lizamma,Varghese, Babu,Sankararaman, S.
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p. 2399 - 2404
(2007/10/02)
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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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