- Nickel-Catalyzed Reductive Cross-Coupling of N-Acyl and N-Sulfonyl Benzotriazoles with Diverse Nitro Compounds: Rapid Access to Amides and Sulfonamides
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Herein we report a Ni-catalyzed reductive transamidation of conveniently available N-acyl benzotriazoles with alkyl, alkenyl, and aryl nitro compounds, which afforded various amides with good yields and a broad substrate scope. The same catalytic reaction conditions were also applicable for N-sulfonyl benzotriazoles, which could undergo smooth reductive coupling with nitroarenes and nitroalkanes to afford the corresponding sulfonamides.
- Qu, Erdong,Li, Shangzhang,Bai, Jin,Zheng, Yan,Li, Wanfang
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supporting information
p. 58 - 63
(2021/12/27)
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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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supporting information
p. 5209 - 5212
(2021/10/19)
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- Synthesis of 3-nitroindoles by sequential paired electrolysis
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3-Nitroindoles are synthetically versatile intermediates but current methods for the preparation hinder their widespread application. Herein, we report that nitroenamines undergo electrochemical cyclisation to 3-nitroindoles in the presence of potassium iodide. Detailed control experiments and cyclic voltammogram studies infer the reaction proceedsviaa sequential paired electrolysis process, beginning with anodic oxidation of iodide (I?) to the iodine radical (I˙), which facilitates cyclisation of the nitroenamine to give a 3-nitroindolinyl radical. Cathodic reduction and protonation generates a 3-nitroindoline that upon oxidation forms the 3-nitroindole.
- Kilmartin, Paul A.,Lindsay, Ashley C.,Sperry, Jonathan
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supporting information
p. 7903 - 7913
(2021/09/28)
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- One-pot synthesis of 5-phenylsulfonyl-3-aroylisoxazolines and 3-aroylisoxazoles from alkynes and (phenylsulfonyl)ethene
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Iron(III) nitrate-assisted cycloaddition of (phenylsulfonyl)ethene to arylacetylenes in the presence of KI affords 5-phenylsulfonyl-3-aroylisoxazolines whose treatment with K2CO3 provides 4,5-unsubstituted 3-aroylisoxazoles. Both synthetic steps can be performed in a one-pot manner.
- Wang, Liang,Zhang, Nana
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p. 390 - 392
(2021/06/07)
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- Sustainable Palladium-Catalyzed Tsuji-Trost Reactions Enabled by Aqueous Micellar Catalysis
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Palladium-catalyzed allylic substitution, or "Tsuji-Trost"reactions, can be run under micellar catalysis conditions featuring not only chemistry in water but also numerous combinations of reaction partners that require low levels of palladium, typically on the order of 1000 ppm (0.1 mol %). These couplings are further characterized by especially mild conditions, leading to a number of cases not previously reported in an aqueous micellar medium. Inclusion of diverse nucleophiles, such as N-H heterocycles, alcohols, dicarbonyl compounds, and sulfonamides is described. Intramolecular cyclizations further illustrate the broad utility of this process. In addition to recycling studies, a multigram scale example is reported, indicative of the prospects for scale up.
- Braga, Felipe C.,Gallou, Fabrice,Lee, Nicholas R.,Lippincott, Daniel J.,Lipshutz, Bruce H.,Moghadam, Farbod A.,Zhu, Bingchun
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supporting information
(2020/07/15)
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- Ionic-Liquid Controlled Nitration of Double Bond: Highly Selective Synthesis of Nitrostyrenes and Benzonitriles
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Unprecedented in literature, the conversion of aryl alkenes into β-nitrostyrenes (2) or benzonitriles (3) with sodium nitrite can be governed by an appropriate choice of ionic liquid (IL) medium. A general trend was found for the selectivity of these processes, which depends on the nature of IL, with imidazolium-based ILs, such as [Bmim]Cl, that favor the C–H nitration leading to β-nitrostyrenes, while tetraalkylammonium-based ILs, such as TBAA, privilege the C=C bond cleavage affording benzonitriles. Besides a substrate scope, mechanistic hypotheses were provided on the origin of the different selectivity in the two kinds of ILs, based on their own tunable properties such as polarity, viscosity, and solvent cage effects.
- Casiello, Michele,Caputo, Daniela,Fusco, Caterina,Cotugno, Pietro,Rizzi, Vito,Dell'Anna, Maria Michela,D'Accolti, Lucia,Nacci, Angelo
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supporting information
p. 6012 - 6018
(2020/08/24)
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- Iron Nitrate-Mediated Selective Synthesis of 3-Acyl-1,2,4-oxadiazoles from Alkynes and Nitriles: The Dual Roles of Iron Nitrate
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A direct strategy for the selective synthesis of 3-acyl-1,2,4-oxadiazoles from alkynes and nitriles has been developed under iron(III) nitrate-mediated conditions. The mechanism includes three sequential procedures: Iron(III) nitrate-mediated nitration of
- Bian, Qilong,Wu, Cunluo,Yuan, Jiangpei,Shi, Zuodong,Ding, Tao,Huang, Yongwei,Xu, Hao,Xu, Yuanqing
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p. 4058 - 4066
(2020/04/10)
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- Denitrative imino-diaza-Nazarov cyclization: Synthesis of pyrazoles
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An iodine-catalyzed denitrative imino-diaza-Nazarov cyclization (DIDAN) methodology has been developed for the synthesis of pyrazoles with high to excellent yields by using α-nitroacetophenone derivatives and in situ generated hydrazones. The key transformation of this oxidative 4π-electrocyclization proceeds through an enamine-iminium ion intermediate. This rapid one-pot DIDAN protocol results in the selective generation of C-C and C-N bonds and cleavage of a C-N bond. This journal is
- Aegurla, Balakrishna,Jarwal, Nisha,Peddinti, Rama Krishna
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p. 6100 - 6107
(2020/10/21)
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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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supporting information
p. 3575 - 3580
(2019/04/14)
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- Imidazolium-Based Ionic Network as a Robust Heterogeneous Catalyst in Synthesis of Phenacyl Derivatives
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A new imidazolium-based poly(ionic liquid) has been synthesized and used as a robust heterogeneous catalyst for the preparation of phenacyl derivatives by an SN2 reaction of different phenacyl bromides with a broad range of nucleophiles. The products are obtained in high yields under mild conditions. The catalyst can be recycled efficiently.
- Kakesh,Sayyahi,Badri,Tahanpesar
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p. 1218 - 1220
(2019/07/16)
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- Diacylfuroxans Are Masked Nitrile Oxides That Inhibit GPX4 Covalently
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GPX4 represents a promising yet difficult-to-drug therapeutic target for the treatment of, among others, drug-resistant cancers. Although most GPX4 inhibitors rely on a chloroacetamide moiety to modify covalently the protein's catalytic selenocysteine residue, the discovery and mechanistic elucidation of structurally diverse GPX4-inhibiting molecules have uncovered novel electrophilic warheads that bind and inhibit GPX4. Here, we report our discovery that diacylfuroxans can act as masked nitrile oxide prodrugs that inhibit GPX4 covalently with unique cellular and biochemical reactivity compared to existing classes of GPX4 inhibitors. These observations illuminate a novel molecular mechanism of action for biologically active furoxans and also expand the collection of reactive groups capable of targeting GPX4.
- Eaton, John K.,Kramm, Anneke,Ruberto, Richard A.,Schreiber, Stuart L.,Viswanathan, Vasanthi S.
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supporting information
(2020/01/02)
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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
-
supporting information
p. 1385 - 1389
(2019/01/09)
-
- Facile synthesis of 2-nitromethyl aromatic ketones by insertion of benzynes into the C-C bond of α-nitroketones
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A facile method to synthesize 2-nitromethyl aromatic ketones was developed. In the method, benzyne was generated in situ for the insertion to α-Nitroketones in one pot to achieve 2-nitromethyl aromatic ketones under mild conditions. Aromatic and aliphatic α-nitroketones were applied in the reaction, and the results show that aliphatic α-nitroketones gave excellent yields (up to 96%), while aromatic α-nitroketones gave moderate yields. The synthesized 2-nitromethyl aromatic ketones could be potential substrates to synthesize isoindoles.
- Hu, Ji-Hong,Zheng, Hong-Jie
-
supporting information
p. 558 - 562
(2019/01/25)
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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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supporting information
p. 6700 - 6704
(2019/09/07)
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- A Continuous-Flow, Two-Step, Metal-Free Process for the Synthesis of Differently Substituted Chiral 1,2-Diamino Derivatives
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The enantioselective organocatalytic reduction of aryl-substituted nitroenamines was successfully performed under continuous-flow conditions. After a preliminary screening with a 10-μL microreactor, to establish the best reaction conditions, the reduction was scaled up in a 0.5-mL mesoreactor, without appreciable loss of enantioselectivity, that remained constantly higher than 90%. The in-flow nitro reduction was also accomplished, either by Raney nickel catalyzed hydrogenation or by a metal-free methodology based on the use of the very inexpensive and readily available reducing agent trichlorosilane. The final aim is to develop a two-step, continuous-flow process for the stereoselective, metal-free, catalytic synthesis of differently functionalized chiral 1,2-diamines.
- Pirola, Margherita,Compostella, Maria Elena,Raimondi, Laura,Puglisi, Alessandra,Benaglia, Maurizio
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supporting information
p. 1430 - 1438
(2018/02/09)
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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
-
supporting information
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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supporting information
p. 4502 - 4508
(2018/11/10)
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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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p. 1130 - 1133
(2018/02/22)
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- Iron-Mediated Synthesis of Isoxazoles from Alkynes: Using Iron(III) Nitrate as a Nitration and Cyclization Reagent
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A simple and direct method for the iron(III) nitrate-mediated synthesis of isoxazoles from alkynes has been developed; both self-coupling and cross-coupling products could be successfully prepared from alkynes. Meanwhile, for the cross-coupling and cyclizing of two different alkynes examined, the iron-mediated system shows a good chemoselectivity for the synthesis of corresponding isoxazoles. In our method, cheap and eco-friendly iron(III) nitrate is used as the nitration and cyclization reagent, and KI is used as the additive; they both play a positive role in this transformation. Furthermore, a different mechanism for the formation of isoxazoles from alkynes has been proposed.
- Lai, Zhenzhen,Li, Zhenxing,Liu, Yawei,Yang, Pengkun,Fang, Xiaomin,Zhang, Wenkai,Liu, Baoying,Chang, Haibo,Xu, Hao,Xu, Yuanqing
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p. 145 - 153
(2018/02/19)
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- Preparation method and application of chiral oxazoline crystal
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The invention discloses a preparation method of a chiral oxazoline crystal (I). 0.6800g of anhydrous ZnCl2, 40ml of chlorobenzene, 6.4023g of 1,4-dinitrile benzene and 19.0464g of D-leucinol are added in synthesis, mixture is refluxed for 24 hours at high
- -
-
Paragraph 0009
(2017/08/31)
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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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supporting information
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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- Catalytic Enantioselective Desymmetrization of Norbornenoquinones via C(sp2)-H Alkylation
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The enantioselective Diels-Alder (DA) reaction with monosubstituted p-benzoquinones is an unmet challenge. A new approach for the enantioselective synthesis of monosubstituted quinone-DA adducts is presented based on C(sp2)-H alkylative desymmetrization of meso-DA adducts. Catalyzed by a tertiary amino-thiourea derivative, this reaction utilizes nitroalkanes as the alkylating agents and generates densely functionalized products bearing at least four contiguous stereogenic centers remote from the reaction site with excellent enantioselectivities.
- Sarkar, Rahul,Mukherjee, Santanu
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supporting information
p. 6160 - 6163
(2016/12/09)
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- Nitration-Oximization of Styrene Derivatives with tert-Butyl Nitrite: Synthesis of α-Nitrooximes
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A highly efficient method for direct nitration-oximization of styrene derivatives using tert-butyl nitrite (t-BuONO) in DMSO was developed. The present method offers a convenient and practical approach for the synthesis of α-nitrooximes in moderate to high yields. The salient features entail mild reaction conditions, metal-free reagent, environmentally benign solvent and simple experimental procedure.
- Chumnanvej, Napasawan,Katrun, Praewpan,Pohmakotr, Manat,Reutrakul, Vichai,Soorukram, Darunee,Kuhakarn, Chutima
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p. 830 - 838
(2016/09/03)
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- Strategic Utilization of Multifunctional Carbene for Direct Synthesis of Carboxylic–Phosphinic Mixed Anhydride from CO2
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Direct synthesis of carboxylic–phosphinic mixed anhydrides has been achieved by treating carbon dioxide with N-phosphine oxide-substituted imidazolylidenes (PoxIms) that contain both nucleophilic carbene and electrophilic phosphorus moieties. This novel mixed anhydride was efficiently derivatized into an ester, an amide, and an unsymmetrical ketone via transformation into its corresponding imidazolium salt followed by a dual substitution reaction. The presented work used well-designed multifunctional carbene reagents to establish a novel utility for carbon dioxide in organic synthesis.
- Hoshimoto, Yoichi,Asada, Takahiro,Hazra, Sunit,Kinoshita, Takuya,Sombut, Panukorn,Kumar, Ravindra,Ohashi, Masato,Ogoshi, Sensuke
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supporting information
p. 16075 - 16079
(2016/12/26)
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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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- Simple route to multisubstituted tetrahydropyrimidines
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Abstract As part of our ongoing investigation into the synthetic application of nitroenamines several new densely substituted pyrimidine and pyrrolo-pyrimidine derivatives were prepared. Thus, 2-nitromethylenepyrrolidine and some open chain nitroenamines of phenyl-(2-nitro-1-phenyl-vinyl)-amine type were reacted with ethyl glyoxylate and a substituted aniline usually in a one-pot procedure to furnish the key intermediates for a subsequent cyclization. These compounds including a molecular fragment of 1,3-diamine type were subjected to a simple ring closure with formaldehyde to give the title compounds in good yields. The protocol reported has the advantages of mild reaction conditions, easy workup and inexpensive reagents. In an attempted removal of the 4-methoxy-phenyl protecting group from the 4-methoxy-phenyl substituted hexahydropyrrolo[1,2-c]pyrimidine derivative, an unexpected periodic acid mediated ring cleavage and phenyl group migration was discovered. The structures of the synthesized new compounds were confirmed by spectral data, and, particularly, the hindered rotation and the unusual 1H NMR characteristics of 4-(4-nitro-phenyl)-but-3-enoic acid ethyl ester derivative were discussed.
- Vincze, Zoltán,Pilipecz, Mihály V.,Scheiber, Pál,Varga, Tamás R.,Tóth, Gábor,Nemes, Péter
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p. 6135 - 6142
(2015/08/03)
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- Copper Nitrate Mediated Regioselective [2+2+1] Cyclization of Alkynes with Alkenes: A Cascade Approach to Δ2-Isoxazolines
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An efficient method for the regioselective synthesis of pharmacologically relevant polysubstituted Δ2-isoxazolines is based on the copper-mediated direct transformation of simple terminal alkynes and alkenes. The overall process involves the formation of four chemical bonds with inexpensive and readily available copper nitrate trihydrate as a novel precursor of nitrile oxides. The reaction can be easily handled and proceeds under mild conditions.
- Gao, Mingchun,Li, Yingying,Gan, Yuansheng,Xu, Bin
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supporting information
p. 8795 - 8799
(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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- 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 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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- Microwave-assisted synthesis of 3-nitroindoles from N-aryl enamines via intramolecular arene-alkene coupling
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A variety of N-aryl β-nitroenamines were effectively transformed into 3-nitroindoles in good yields and with complete regioselectivity via a rapid microwave (μW) assisted intramolecular arene-alkene coupling reaction. This report further demonstrates the versatility of this method by constructing 3-carboalkoxy-and 3-cyanoindoles. Optimization data, substrate scope, and applications are discussed.
- Nguyen, Huy H.,Kurth, Mark J.
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supporting information
p. 362 - 365
(2013/03/13)
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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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supporting information
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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supporting information; experimental part
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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supporting information; experimental part
p. 8972 - 8981
(2011/08/04)
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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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supporting information; experimental part
p. 8979 - 8981
(2011/11/30)
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- Geminal acylnitrostyrenes in the reaction with ortho-aminothiophenol
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The synthesis of previously unknown 2,3- and 2,5-dihydro-1,5- benzothiazepines sontaining nitro group was performed by the easy sondensation of geminal acylnitrostyrenes with the o-aminothiophenol. The structure of the obtained sompounds was studied by physicochemical methods. By X-ray diffraction analysis the geometry and structural parameters of 4-methyl-3-nitro-2-phenyl-2, 3-dihydro-1,5-benzothiazepine were determined. Pleiades Publishing, Ltd., 2011.
- Berestovitskaya,Baichurin,Aboskalova,Lysenko,Anan'evb
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experimental part
p. 1163 - 1170
(2011/10/17)
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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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- 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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- PIDA-mediated oxidative C-C bond formation: Novel synthesis of indoles from n-aryl enamines
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A variety of functionalized indoles were synthesized from N-aryl enamines via PIDA-mediated oxidative carbon-carbon bond formation. The features of the present reaction include facilitative preparation of substrates 2, good functional group tolerance, and mild reaction conditions without transition metals.
- Yu, Wenquan,Du, Yunfei,Zhao, Kang
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supporting information; experimental part
p. 2417 - 2420
(2009/11/30)
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- Regioselective synthesis of functionalized 4-nitro- and 4-amino-phenols based on formal [3+3] cyclocondensations of 3-ethoxy-2-nitro-2-en-1-ones with 1,3-bis(silyloxy)-1,3-butadienes
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Functionalized 4-nitro- and 4-aminophenols were regioselectively prepared based on [3+3] cyclizations of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with 3-ethoxy-2-nitro-2-en-1-ones.
- Riahi, Abdolmajid,Shkoor, Mohanad,Khera, Rasheed Ahmad,Reinke, Helmut,Langer, Peter
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body text
p. 3017 - 3019
(2009/09/28)
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- Regioselective synthesis of amino- and nitroarenes based on [3+3] cyclocondensations of 1,3-bis(silyloxy)-1,3-butadienes
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Functionalized amino- and nitro-substituted biaryls and dibenzo[b,d]pyrid-6-ones (6(5H)-phenanthridinones) were prepared by [3+3]cyclocondensation of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with nitro-substituted 1-aryl-1-silyloxy-1-en-3-ones and subsequent hydrogenation. 4-Nitro- and 4-aminophenols were prepared based on formal [3+3] cyclizations of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with 3-ethoxy-2-nitro-2-en-1-ones.
- Riahi, Abdolmajid,Shkoor, Mohanad,Fatunsin, Olumide,Yawer, Mirza A.,Hussain, Ibrar,Fischer, Christine,Langer, Peter
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scheme or table
p. 9300 - 9315
(2009/12/28)
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- Oxidation of azides by the HOF·CH3CN: A novel synthesis of nitro compounds
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The HOF·CH3CN complex, readily prepared by passing F 2 through aqueous acetonitrile, is an exceptionally efficient oxygen transfer agent. It is unique in its capacity to oxidize various azides into the corresponding nitro derivatives. This method requires short reactions times and room temperature or below, and the desired nitro compounds were usually isolated in very good yields. The respective nitroso derivatives are believed to be the intermediates in this reaction. Functional groups such as aromatic rings, ketones, nitriles, halides, alcohols, and esters are tolerated. Sulfides react with HOF·CH3CN usually at the same rate as azides. Amines and olefins, however, react faster, so they have to be protected first. Nitro derivatives with various oxygen isotopes can be made using the labeled H 18OF·CH3CN. In the case of chiral azides the stereochemistry around the nitrogen-bonded carbons is retained.
- Carmeli, Mira,Rozen, Shlomo
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p. 4585 - 4589
(2007/10/03)
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- α-nitro ketone synthesis using N-acylbenzotriazoles
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Readily available N-acylbenzotriazoles 2a-1 (derived from a variety of aliphatic, (hetero)aromatic, and N-protected α-amino carboxylic acids) smoothly convert primary 3a-c and α-functionalized primary nitroalkanes 3d into the corresponding α-nitro ketones
- Katritzky, Alan R.,Abdel-Fattah, Ashraf A. A.,Gromova, Anna V.,Witek, Rachel,Steel, Peter J.
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p. 9211 - 9214
(2007/10/03)
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- Substituted 5-dinitromethyl-3-phenyl-1,2,4-oxadiazoles in reactions with arylethenes
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Reactions of substituted 5-dinitromethyl-3-phenyl-1,2,4-oxadiazoles with arylethenes of various nucleophilicity, number and position of substituents attached to the double bond give rise to nitroalkenes and secondary products resulting from α-nitroketones or nitroalcohols O-alkylation. The direction of transformations in the arising ion pair is governed predominantly by steric effects.
- Tyrkov
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p. 890 - 892
(2007/10/03)
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- Photolysis of α-azidoacetophenones: Direct detection of triplet alkyl nitrenes in solution
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We report the first detection of triplet alkyl nitrenes in fluid solution by laser flash photolysis of α-azido acetophenone derivatives, 1. Azides 1 contain an intramolecular triplet sensitizer, which ensures formation of the triplet alkyl nitrene by bypassing the singlet nitrene intermediate. At room temperature, azides 1 cleave to form benzoyl and methyl azide radicals in competition with triplet energy transfer to form triplet alkyl nitrene. The major photoproduct 3 arises from interception of the triplet alkyl nitrene with benzoyl radicals. The triplet alkyl nitrene intermediates are also trapped with molecular oxygen to yield the corresponding 2-nitrophenylethanone. Laser flash photolysis of 1 reveals that the triplet alkyl nitrenes have absorption around 300 nm. The triplet alkyl nitrenes were further characterized by obtaining their UV and IR spectra in argon matrices. 13C and 15N isotope labeling studies allowed us to characterize the C-N stretch of the nitrene intermediate at 1201 cm-1.
- Singh, Pradeep N. D.,Mandel, Sarah M.,Robinson, Rachel M.,Zhu, Zhendong,Franz, Roberto,Ault, Bruce S.,Gudmundsdottir, Anna D.
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p. 7951 - 7960
(2007/10/03)
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- A Catalytic Deprotection of S,S-, S,O- and O,O-Acetals Using Bi(NO3)3·5 H2O under Air
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S,S-Acetals are smoothly deprotected with air in the presence of a catalytic amount of Bi(NO3)3·5 H2O (1-50 mol %) under ambient conditions to regenerate the original carbonyl compounds in good to excellent yield. This mild, simple, and environmentally benign system is successfully applied to the deprotection of S,O- and O,O-acetals and is compatible with various functional groups. From the mechanistic study of the reaction, the catalytic cycle is considered to be composed of the following four steps: (1) the nitrososulfonium ion of the S,S-acetal is formed by attack of nitrosonium ion (NO+) generated from Bi(NO3)3·5 H2O through the equilibrium wth NO2, (2) the nitrososulfonium ion is hydrolyzed to afford the hemithioacetal and thionitrite, (3) the hemithioacetal collapses to the original carbonyl compound and thiol, which is oxidized by NO+ to give disulfide and NO via thionitrite, and (4) the NO captures molecular oxygen from air to regenerate NO2.
- Komatsu, Naoki,Taniguchi, Azusa,Wada, Shinobu,Suzuki, Hitomi
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p. 473 - 480
(2007/10/03)
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- The chemistry of peroxynitrite: Involvement of an ET process in the radical nitration of unsaturated and aromatic systems
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Reactions of peroxynitrous acid, HPN, with styrene under acidic conditions lead to the oxime 1, the nitrate 2, benzaldehyde (3), and α-nitroacetophenone (4) in overall yields that depend strongly on the pH value and with a product distribution that depends on the dioxygen concentration. The results are rationalized by assuming that HPN undergoes acid-catalyzed decomposition to give nitrous anhydride, or its synthetic equivalent, which is responsible for the regioselective nitration of the styrene double bond by an ET process. The resulting β-nitrobenzyl radical 6 can, depending on the reaction conditions, undergo reversible coupling with nitric oxide to afford the nitroso derivative 7 and then the tautomeric oxime 1, or trapping by dioxygen, eventually leading to products 2, 3, and 4 through the intermediacy of the peroxynitrite derivative 8. Oxime 1 and nitrate 2 are also obtained by treating styrene with nitrous anhydride under protic conditions, the latter being produced in situ from nitric oxide/dioxygen. Similarly to styrene, 1,4-diphenylbutadiene (14) gives radicals 22 and 21 by competitive trapping at the side chain and at the aromatic ring. In turn, radicals 22 and 21 undergo β-fragmentation reactions or trapping by dioxygen with eventual formation of nitrates 16 and 17, cinnamic aldehyde (18), and the diol 15. Finally, the HPN-promoted reaction of p-cresol (27) leads to the 2-nitro derivative 28 through an initial electron-transfer process followed by in cage recombination of the resulting radical ion pair.
- Grossi, Loris,Montevecchi, Pier Carlo,Strazzari, Samantha
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p. 741 - 748
(2007/10/03)
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