- Photoinduced Iron-Catalyzed ipso-Nitration of Aryl Halides via Single-Electron Transfer
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A photoinduced iron-catalyzed ipso-nitration of aryl halides with KNO2 has been developed, in which aryl iodides, bromides, and some of aryl chlorides are feasible. The mechanism investigations show that the in situ formed iron complex by FeSO4, KNO2, and 1,10-phenanthroline acts as the light-harvesting photocatalyst with a longer lifetime of the excited state, and the reaction undergoes a photoinduced single-electron transfer (SET) process. This work represents an example for the photoinduced iron-catalyzed Ullmann-type couplings.
- Wu, Cunluo,Bian, Qilong,Ding, Tao,Tang, Mingming,Zhang, Wenkai,Xu, Yuanqing,Liu, Baoying,Xu, Hao,Li, Hai-Bei,Fu, Hua
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p. 9561 - 9568
(2021/08/06)
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- Bismuth nitrate as a source of nitro radical in ipso-nitration of carboxylic acids
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Aromatic nitro compounds are extensively used in synthetic chemistry. We disclose a new approach to obtain nitroarenes regioselectively starting from carboxylic acids under acid-free reaction conditions.
- Agasti, Soumitra,Maiti, Siddhartha,Maity, Soham,Anniyappan,Talawar,Maiti, Debabrata
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p. 120 - 124
(2019/05/22)
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- Organocatalytic oxidation of substituted anilines to azoxybenzenes and nitro compounds: Mechanistic studies excluding the involvement of a dioxirane intermediate
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An organocatalytic and environmentally friendly approach for the selective oxidation of substituted anilines was developed. Utilizing a 2,2,2-trifluoroacetophenone-mediated oxidation process, substituted anilines can be transformed into azoxybenzenes, while a simple treatment with MeCN and H2O2 leads to the corresponding nitro compounds, providing user-friendly protocols that can be easily scaled up. Various substitution patterns and functional groups were tolerated leading to products in high to excellent yields. Mechanistic studies utilizing HRMS provide clear evidence for the distinct mechanistic intermediates that are involved. This study constitutes an indirect proof excluding the involvement of a dioxirane intermediate in the green organocatalytic oxidation, utilizing 2,2,2-trifluoroacetophenone as the catalyst.
- Voutyritsa, Errika,Theodorou, Alexis,Kokotou, Maroula G.,Kokotos, Christoforos G.
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supporting information
p. 1291 - 1298
(2017/06/06)
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- Substitution of the nitro group with Grignard reagents: Facile arylation and alkenylation of pyridine N-oxides
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The unprecedented substitution of a nitro group with aryl or alkenyl groups of Grignard reagents affords 2-aryl or alkenylpyridine N-oxides in modest to high yields with high chemoselectivity. This protocol allows a simple and clean synthesis of various 2
- Zhang, Fang,Zhang, Song,Duan, Xin-Fang
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supporting information
p. 5618 - 5620
(2013/01/15)
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- Copper catalyzed ipso-nitration of iodoarenes, bromoarenes and heterocyclic haloarenes under ligand-free conditions
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A catalytic protocol for the conversion of haloarenes into the corresponding nitroarenes is presented using copper salts under ligand-free conditions. The method was effectively utilized for the ipso-nitration of a broad variety of haloarenes that includes iodoarenes, bromoarenes, and heterocyclic haloarenes.
- Amal Joseph,Priyadarshini,Lakshmi Kantam,Maheswaran
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supporting information; experimental part
p. 1511 - 1513
(2012/03/27)
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- Microwave-accelerated fluorodenitrations and nitrodehalogenations: expeditious routes to labeled PET ligands and fluoropharmaceuticals
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Methods for the expeditious fluorination of arenes have been investigated, using readily available fluoride sources. An optimized procedure for microwave-accelerated fluorodenitration has been developed, giving good to excellent yields in less than 10 min, rendering it practical for use in the preparation of F18 labeled ligands for PET imaging. Application of the method in the synthesis of CNS agents is demonstrated, and a practical method for the preparation of substrates is also presented.
- LaBeaume, Paul,Placzek, Michael,Daniels, Mathew,Kendrick, Ian,Ng, Patrick,McNeel, Melissa,Afroze, Roushan,Alexander, Abigail,Thomas, Rhiannon,Kallmerten, Amy E.,Jones, Graham B.
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experimental part
p. 1906 - 1909
(2010/09/07)
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- A convenient method for the oxidation of aromatic amines to nitro compounds using tetra-n-alkylammonium bromates
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Tetra-n-propyl and tetra-n-butylammonium bromates were used for the oxidation of a variety of aromatic amines to nitro compounds. Reaction condition and recovery simple and yield of products high.
- Das, Satya Sandhya,Nath, Utpal,Deb, Dibakar,Das, Pranab J.
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p. 2359 - 2363
(2007/10/03)
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- Nitration of heteroaryltrimethyltins by tetranitromethane and dinitrogen tetroxide: Mechanistic aspects, scope and limitations
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The nitration of 2-(trimethylstannyl)heteroarenes by tetranitromethane (TNM) or dinitrogen tetroxide has been shown to be possible when the HOMO energy of the heteroaryltin is high enough to allow the formation of the corresponding radical cation. The reaction proceeds through a charge-transfer complex between heteroaryltin and TNM, followed by a single-electron transfer, which is enhanced under sun-lamp irradiation. Accordingly, 2-nitrobenzo[b]furan, 2-nitrobenzo[b]thiophene, 2-nitropyridine and 2-nitroindoles were obtained by this method. However, the nitration of 2-stannylated pyrimidine or of stannylated 1,3,5-triazines has been shown to be impossible, due to the low energy of their HOMO orbitals. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Fargeas, Valerie,Favresse, Fabien,Mathieu, Didier,Beaudet, Isabelle,Charrue, Pierre,Lebret, Bruno,Piteau, Marc,Quintard, Jean-Paul
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p. 1711 - 1721
(2007/10/03)
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- 2-, 3- and 4-[18F]fluoropyridine by no-carrier-added nucleophilic aromatic substitution with K[18F]F-K222 - A comparative study
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Compared to homoaromatic and aliphatic nucleophilic radiofluorinations, only few references can be found in the literature describing nucleophilic substitutions with [18F]fluoride ion of heteroaromatic compounds such as pyridines and only reactions involving fluorination processes at the ortho-position (2-position) have been more intensively studied. In the present paper, the scope of the nucleophilic aromatic fluorinations at the meta- and paraposition of the pyridine ring with no-carrier-added [18F] fluoride ion as its activated K [18F]F-K222 complex has been evaluated and compared to the nucleophilic aromatic fluorinations at the ortho-position in this pyridine series. The syntheses of 3- and 4- [ 18F]fluoropyridines were chosen as model reactions and compared to the radiosynthesis of 2-[18F]fluoropyridine. The parameters studied include the influence of the position of the leaving group at the pyridine ring, as well as the quantity of the precursor used, the type of activation (conventional heating, microwave irradiation), the solvent, the temperature and the reaction time. Using the corresponding nitro precursor, high yields were obtained at the 2-position (94% yield) using microwaves (100 W) for 2 min in DMSO. Good yields (up to 72%) were observed at the 4-position using the same conditions while practically no reaction was observed at the 3-position. About 60% yield was also obtained at both the 2- and 4-position using the corresponding nitro precursor at 145°C for 10 min in DMSO. Copyright
- Karramkam,Hinnen,Vaufrey,Dolle
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p. 979 - 992
(2007/10/03)
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- Bicyclic heteroaryl compounds as inhibitors of the interaction between the integrin alpha4beta1 receptor and vcam-1 and/or fibronectin
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A compound of formual (I) or pharmaceutically acceptable salts or derivatives thereof; wherein variables are as defined in the specification. The compounds are useful in the treatment of disease mediated by the interaction between VCAM-1 and/or fibronectin and the integrin receptor α4β1. Pharmaceutical compositions and methods of use or treatment are also described and claimed.
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- Organotin mediated nitration in heteroaromatic series using tetranitromethane or dinitrogen tetroxide
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2-Trimethylstannylated benzo[b]furan, benzo[b]thiophene, N-substituted indoles and pyridine afford the corresponding nitro derivatives in regioselective fashion upon treatment with tetranitromethane (using sun-lamp irradiation in the case of N-containing
- Favresse, Fabien,Fargeas, Valérie,Charrue, Pierre,Lebret, Bruno,Piteau, Marc,Quintard, Jean-Paul
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p. 187 - 190
(2007/10/03)
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- 2-[18F]Fluolropyridines by no-carrier-added nucleophilic aromatic substitution with [18F]FK-K222 - A comparative study
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The scope of the nucleophilic aromatic substitution reaction of 2-substituted pyridines with no-carrier-added [13F]fluoride ion (half life: 110 minutes) as its [18F]FK-K222 activated complex, has been evaluated via the radiosynthesis of 2-[18F]fluoropyridine, chosen as a model reaction. The parameters studied include the influence of the leaving group in the 2 position of the pyridine ring, the quantity of the precursor used, the type of activation (conventional heating, micro- and ultrasonic wave irradiations), the solvent, the temperature and the duration of the reaction. Concerning the influence of the leaving group, 2-chloro- and 2-bromopyridine gave moderate to good fluorine-18 incorporation yields while 2-nitro- and especially 2-trimethylammonium pyridine gave excellent incorporation yields. Noteworthy, 2-iodopyridine was almost unreactive. As expected, the incorporation yield increased with the quantity of precursor used: high yields were observed from about 7 μmol of precursor. Using conventional heating and regardless of the substituent in the 2 position of the pyridine ring, the best yields for the radiosynthesis of 2-[11F]fluoropyridine were obtained when the temperature of the reaction was 180°C and the solvent DMSO. The yields for the 2-nitro- and the 2-trimethylammonium pyridine precursors were 77% and 88% respectively, after only 5 minutes of reaction and were similar to those observed at 150°C for longer reaction times. At 120°C, neither the 2-chloro- nor the 2-bromopyridine gave any incorporation. Using microwave irradiations, excellent incorporation yields (96%) were observed for the 2-trimethylammonium pyridine from 1 minute of reaction at 100 Watt in DMSO. Concerning the 2-chloro-, 2-bromo- and 2-nitropyridine, the use of 100 Watt microwave irradiations for 2 minutes gave yields comparable to those obtained for 10 minutes of conventional heating at 180°C, 22%, 71% and 58% respectively. No incorporation at all of the radioactivity could be detected when ultrasonic waves were applied, even with long reaction time and high power.
- Dolci, Lilian,Dolle, Frederic,Jubeau, Sebastien,Vaufrey, Francoise,Crouzel, Christian
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p. 975 - 985
(2007/10/03)
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- Certain herbicidal 1,2,4-triazolo[4,5-b]pyridines
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A compound of formula (I): STR1 in which the dotted lines indicate the presence of two double bonds arranged so as to form a fused hetero-aromatic ring system; Ar is an optionally substituted aryl or heterocyclic ring; W is O or NR1, where R1 is hydrogen or lower alkyl; X is (CH2)n, CH=CH, CH(OR5)CH2, COCH2 ; where n is O, 1 or 2; R2 and R3 are independently selected from H, optionally substituted alkyl, alkenyl or alkynyl, halogen, NR6 R7 or R2 and R3 together with the carbon to which they are attached form an optionally substituted alkenyl or cycloalkyl group; R4 is CO2 R8, CN, COR8, CH2 OR8, CH(OH)R8, CH(OR8)R9, CSNH2, COSR8, CSOR8, CONHSO2 R8, CONR10 R11, CONHNR10 R11, CONHN+ R10 R11 R12 R13-, CO2- R14+ or COON=CR10 R11 ; R14+ is an agriculturally acceptable cation; and R13- is an agriculturally acceptable anion; R5, R8 and R9 are independently selected from H or an optionally substituted alkyl, aryl, alkenyl or alkynyl group; and R6, R7, R10, and R12 are independently selected from H or an optionally substituted alkyl, alkenyl, aryl or alkynyl group or any two of R6, R7, R10, R11 and R12 together with the atom to which they are attached form a cycloalkyl or heterocyclic ring. Compounds of formula (I) are herbicidal and composition containing them and methods of treatment using them are also described.
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- Caveat Regarding the Use of Substituent Parameters in Statistical Analyses of Molecular Properties. II Case Study: Carbon-13 N.M.R. of 2-Substituted Pyridines and Monosubstituted Benzenes
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Carbon-13 n.m.r. substituent chemical shifts of equivalent positions on monosubstituted benzenes and 2-substituted pyridines are analysed by multiple linear regression on combinations of a field, resonance, electronegativity and three polarizability parameters.The ortho and meta positions of the 2-pyridine and benzene series are poorly described by ?F and ?R parameters, but a much improved fit is obtained when ?X and/or a bond polarizability parameter ?α(C-X) are included.The mechanism of shift formation differs markedly between the two systems when the C2, C4 and C6 positions on pyridine are compared with the geometrically equivalent positions on benzenes.Owing to the high degree of interdependence between the four substituent effects, quantitative analysis proved to be impossible.However, use of subsets of substituents with three of the four parameters approximately orthogonal enabled the mechanism to be deduced in most cases.It is postulated that the differences between the pyridine and benzene systems arises from perturbation of the C-N bond polarity.A mechanism to explain the results is presented.
- Cook, Iain B.
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p. 1493 - 1518
(2007/10/02)
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- Site-Selectivity in the Cyanation of 3-Substituted Pyridine 1-Oxides with Trimethylsilanecarbonitrile
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The cyanation of 3-halo-, 3-methoxy-, and 3-dimethylaminopyridine 1-oxide with trimethylsilanecarbonitrile gave predominantly the corresponding 3-substituted 2-pyridinecarbonitriles.The deoxygenation of nitropyridine 1-oxides to nitropyridines with the same reagent is also described.Keywords - site-selective reaction; trimethylsilanecarbonitrile; pyridine 1-oxide; 2-pyridine-carbonitrile; nitropyridine 1-oxide; deoxygenation; aromatic amine N-oxide; cyanation
- Sakamoto, Takao,Kaneda, Soh-ichi,Nishimura, Sumiko,Yamanaka, Hiroshi
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p. 565 - 571
(2007/10/02)
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- Bipyridines. Part XV. A Novel Convenient Synthesis of Some 3,3'-Bipyridine Derivatives
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A new, convenient synthesis of 2,2'-dinitro-(10), 4,4'-dinitro-(11), 1,1'-dioxo-4,4'-dinitro- (12) and 2,2'-dioxo- (13) -3,3'-bipyridines by aplication of the Ullmann reaction is reported.The possibility of the nitro-groups substitution by such nucleophil
- Becalski, Adam,Kaczmarek, Lukasz,Nantka-Namirski, Pawel
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p. 105 - 114
(2007/10/02)
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- Conversion of a Primary Amino Group into a Nitroso Group. Synthesis of Nitroso-Substituted Heterocycles
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2-Aminopyridine, 2-amino-4-methylpyridine, 1-aminoisoquinoline, 2-aminopyrimidine, and 2-aminopyrazine have been converted to the corresponding nitroso compounds by reaction with dimethyl sulfide and N-chlorosuccinimide, deprotonation of the resulting sul
- Taylor, Edward C.,Tseng, Chi-Ping,Rampal, Jang B.
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p. 552 - 555
(2007/10/02)
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