- N-Nitroheterocycles: Bench-Stable Organic Reagents for Catalytic Ipso-Nitration of Aryl- And Heteroarylboronic Acids
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Photocatalytic and metal-free protocols to access various aromatic and heteroaromatic nitro compounds through ipso-nitration of readily available boronic acid derivatives were developed using non-metal-based, bench-stable, and recyclable nitrating reagents. These methods are operationally simple, mild, regioselective, and possess excellent functional group compatibility, delivering desired products in up to 99% yield.
- Budinská, Alena,Katayev, Dmitry,Passera, Alessandro,Zhang, Kun
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supporting information
(2020/03/30)
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- A one-pot synthesis of 3-nitrothiophene and 3-nitro-2-substituted thiophenes
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A one-pot approach to the synthesis of 3-nitrothiophene and 3-nitro-2-substituted thiophenes has been developed. Exposure of 1,4-dithane-2,5-diol to nitroacetates or nitroalkenes in the presence of 25% triethylamine and subsequent treatment with molecular sieves and combinations of silica gel or acidic alumina with DDQ or chloranil formed 3-nitrothiophene or a number of 3-nitro-2-substituted thiophenes with complete regiocontrol. A simple work-up procedure removes the requirement for purification by chromatography for most post-synthetic applications.
- McNabola, Neasa,O'Connor, Cornelius J.,Roydhouse, Mark D.,Wall, Michael D.,Southern, J. Mike
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p. 4598 - 4603
(2015/06/08)
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- Ipso-nitration of arylboronic acids with bismuth nitrate and perdisulfate
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An efficient and one pot synthetic method of ipso-nitration of arylboronic acids has been developed. The high efficiency, general applicability, and broader substrate scope including heterocycles and functional groups make this method advantageous. Due to its simplicity, we expect to find application of this method in synthesis.
- Manna, Srimanta,Maity, Soham,Rana, Sujoy,Agasti, Soumitra,Maiti, Debabrata
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supporting information; experimental part
p. 1736 - 1739
(2012/05/20)
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- Convenient and mild synthesis of nitroarenes by metal-free nitration of arylboronic acids
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A novel methodology for the direct nitration of arylboronic acids has been developed. By using inexpensive tert-butyl nitrite various aromatic nitro compounds are produced in moderate to good yields (45-87%) without the need of any catalyst.
- Wu, Xiao-Feng,Schranck, Johannes,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 12462+12463
(2012/02/03)
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- Facile synthesis of 3-nitro-2-substituted thiophenes
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A new approach to 3-nitro-2-substituted thiophenes has been developed. Exposure of commercially available 1,4-dithane-2,5-diol to nitroalkenes in the presence of 20% triethylamine results in a tandem Michael?intramolecular Henry reaction to form the corresponding tetrahydrothiophene. Subsequent microwave irradiation on acidic alumina in the presence of chloranil effects the solvent free dehydration and aromatization to form 3-nitro-2-substituted thiophenes cleanly and rapidly. A simple workup procedure removes the requirement for purification by chromatography in most cases.
- O Connor, Cornelius J.,Roydhouse, Mark D.,Przybyl, Anna M.,Wall, Michael D.,Southern, J. Mike
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supporting information; experimental part
p. 2534 - 2538
(2010/07/17)
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- Studies on the biological activity of some nitrothiophenes
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The biological activity of nineteen substituted thiophenes (3) have been assessed by evaluating the minimum inhibitory concentration required to inhibit the growth of E. coli, M. luteus and A. niger. The series displays a wide range of activities with 2-chloro-3,5-dinitrothiophene (3a) or 2-bromo-3,5- dinitrothiophene (3c) showing the highest activity against all three organisms, while the simplest compound of the series, 2-nitrothiophene (3s) shows the smallest activity in each case. The mode of action of 3a and 3c is thought to involve nucleophilic attack by intracellular thiols at the 2-position of the heterocyclic ring leading to displacement of halogen, but other active derivatives, such as 2,4-dinitrothiophene (3h) and 5-nitrothiophene-2- carbaldehyde (3d) which have no displaceable halogen or leaving group are thought to act by forming Meisenheimer complexes. The Royal Society of Chemistry 2006.
- Morley, John O.,Matthews, Thomas P.
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p. 359 - 366
(2008/01/27)
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- A mild and efficient method for the mononitration of aromatic compounds by cerium (III) ammonium nitrate in acetic anhydride
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A mild and efficient method for the mononitration of aromatic and olefinic compounds is described. This method is especially useful for active substrates.
- Tanemura, Kiyoshi,Suzuki, Tsuneo,Nishida, Yoko,Satsumabayashi, Koko,Horaguchi, Takaaki
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p. 497 - 499
(2007/10/03)
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- A novel method for the nitration of simple aromatic compounds
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Simple aromatic compounds such as benzene, alkylbenzenes, halogenobenzenes, and some disubstituted benzenes are nitrated in excellent yields with high regioselectivity under mild conditions using zeolite β as a catalyst and a stoichiometric quantity of nitric acid and acetic anhydride. The zeolite can be recycled, and the only byproduct is acetic acid, which can be separated easily from the nitration product by distillation; the process is inexpensive and represents an attractive method for the clean synthesis of a range of nitroaromatic compounds. For example, nitration of toluene gives a quantitative yield of mononitrotoluenes, of which 79% is 4-nitrotoluene; fluorobenzene gives a quantitative yield of mononitro compounds, of which 94% is 4-nitrofluorobenzene; and 2-fluorotoluene gives a 96% yield of mononitro products, of which 90% is the 5-nitro isomer and 10% is the 4-nitro isomer.
- Smith, Keith,Musson, Adam,DeBoos, Gareth A.
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p. 8448 - 8454
(2007/10/03)
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- Five membered ring analogues of nifedipine - Part 1: 2-Nitro-3-furanecarbaldehyde and 2-nitro-3-thiophenecarbaldehyde in the Hantzsch pyridine synthesis
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The heterocyclic aldehydes 4 in the Hantzsch pyridine synthesis afforded dependent on the choosen variation, either the 1,4-dihydropyridines (DHP) 5, the 1,2-DHP 6 or the 1,2,3,4-tetrahydropyrimidines (THPM) 7 as main products. 5-7 were dehydrogenated to the corresponding heteroaromatics 8-10 by cerium(IV). The lactames 11 and 12 were isolated by appropiate reduction of the nitro group from 8 and 9 by neighbour group participation of an ester function. The synthesis of 12 represents for the second time the evidence of an 2-aminofurane compound. 11 and 12 were converted with phosphorous oxychloride to form the annulated chloronaphthyridines 13 and 14 which were cyclized with sodium azide to yield the tetrazoles 15 and 16. The half wave potentials E1/2 of the DHP and THPM 5-7 were determined by anodic oxidation with the rotating platinum electrode using difference pulse voltammetry (DPV). These are comparable with those of the 2-nitrophenyl analogues.
- Goerlitzer,Dobberkau
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p. 386 - 391
(2007/10/03)
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- An easy synthesis of 3-amino- and 3-nitrothiophene
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3-Amino- and 3-nitrothiophene are readily made by the decarboxylation of the corresponding thiophene-2-carboxylic acids which are easily prepared from the commercially available methyl 3-aminothiophene-2-carboxylate.
- Barker,Huddleston,Wood
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p. 3729 - 3734
(2007/10/03)
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- Synthesis and antibacterial activity of 4,7-dihydro-4-ethyl-7-oxothieno(3,2-b)pyridine-6-carboxylic acids
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The synthesis of some new 4,7-dihydro-4-ethyl-7-oxothieno(3,2-b)pyridine-6-carboxylic acids with various substituents on position 2 is described. The evaluation of the anti-bacterial activity of some compounds shows an activity different to those of the thieno(2,3-b)pyridine series.
- Malicorne,Bompart,Giral,Despaux
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- PROTIODESILYLATION OF SUBSTITUTED 2-TRIMETHYLSILYLTHIOPHENS
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First-order rate constats at 50 deg C have been determined for cleavage of the thiophen compounds XC4H2SSiMe3-2 in mixtures of (a) MeOH (5 vol.) with aqueous HClO4 (2 vol.) and (b) CH3CO2H (4 vol.) with aqueous H2SO4 (3 vol.) Relative rates krel, in the first medium are (X =) 5-OMe, 7 200; 5-Me, 36; H, 1.00; 5-Cl, 1.08E-1; 5-Br, 9.0E-2; 3-Br, 5.0E-2; 4-Br, 4.9E-3, and in the second medium 5-Me, 36; H, 1.00; 5-Cl, 1.28E-1; 5-Br, 9.8E-2; 3-Br, 5.5E-2; 4-Br, 6.5E-3; 5-NO2, 9.1E-7; 3-NO2, 7.1E-7.Except for the nitro-compounds, the two sets of log krel values show excellent linear correlations with values for the corresponding XC6H4SiMe3 compounds, with 3-, 4-, and 5-X in the thiophen ring being taken as equivalent to o-, m-, and p-X groups, respectively, in the benzene ring, the effects of substituents being a litle larger in the thiophen than the benzene system; 3- and 5-O2NC4H2SSiMe3 are less reactive than would be expected from the correlations.Again with the exception of the data for the nitro-compound, the krel values for the 4- and 5- substituted thiophens show very good correlation with ?m+ and ?p+ constants.
- Seconi, Giancarlo,Eaborn, Colin
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p. 931 - 934
(2007/10/02)
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- THE RATES OF BASE CLEAVAGE OF SUBSTITUTED 2-THIENYLTRIMETHYLSILANES. AB INITIO CALCULATIONS OF THE ACIDITIES OF MONOSUBSTITUTED THIOPHENS
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Rates of cleavage in NaOMe-MeOH at 50 deg C have been determined for the mono-substituted 2-trimethylsilylthiophens X*C4H2S*SiMe3-2 with X = H, 3-NO2, 3-Br, 4-Br-, and 5-NO2, -CN, -COPh, -Me, -OMe and -NMe2, and for one disubstituted compound, 4,5-Br2*C4HS*SiMe3-2.For several compounds the rate and product isotope effects have also been determined.The energies involved in the process X*C4H3S X*C4H2S- for deprotonation at the 2-position have been calculated by an ab initio method (STO-3G), and the results used in analysis of the substituent effects in the cleavage of the XC4H2S*SiMe3-2 compounds.The results are consistent with the view the aryl anions separate in the rate-determining step of the cleavage.The isotope effects are all close to unity, whereas by comparison with results for XC6H4CH2SiMe3 and related species of similar reactivity, values in the region of 10 would be expected for the 3- and 5-NO2 compounds if the product isotope effect for a carbanion R depended only in the pKa of RH.The difference between the thienyl- and benzyl-type anions is attributed to the absence of conjugative delocalization of the charge in the former. Approximate pKa values are derived for the 2-positions of the X*C4H3S compounds.
- Seconi, Giancarlo,Eaborn, Colin,Stamper, John G.
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p. 153 - 168
(2007/10/02)
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