4920-84-7Relevant articles and documents
Aromatic nitration with bismuth nitrate in ionic liquids and in molecular solvents: A comparative study of Bi(NO3)3·5H 2O/[bmim][PF6] and Bi(NO3)3· 5H2O/1,2-DCE systems
Jacoway, Jonathan,Kumar, G. G. K. S. Narayana,Laali, Kenneth K.
, p. 6782 - 6785,4 (2012/12/12)
A suspension of bismuth nitrate pentahydrate (BN) in [bmim][PF6] or [bmim][BF4] imidazolium ionic liquid (IL) is an effective reagent for ring nitration of activated aromatics under mild conditions without the need for external promoters. Nitration can also be effected in 1,2-DCE, MeCN, or MeNO2 without additives. Nitration of activated arenes (anisole, toluene, ethylbenzene, cumene, p-xylene, mesitylene, durene, and 1,3-dimethoxybenzene) is considerably faster (time to completion) in BN/[bmim][PF6] relative to BN/1,2-DCE and there are also differences in isomer distributions (for anisole, toluene, and ethylbenzene). With introduction of strongly deactivating substituents (-CHO; -MeCO; -NO 2) the BN/IL system is no longer active but reactions still proceed with BN/1,2-DCE in reasonable yields. The ready availability and low cost of BN, simple operation, and absence of promoters, coupled to recycling and reuse of the IL, provide an attractive alternative to classical nitration methods for activated arenes. Switching from Bi(NO3)3·5H 2O/[bmim][PF6] to Bi(NO3)3· 5H2O/1,2-DCE increases the scope of the substrates that can be nitrated.
Designing Structural Motifs for Clickamers: Exploiting the 1,2,3-Triazole Moiety to Generate Conformationally Restricted Molecular Architectures
Zornik, Denise,Meudtner, Robert M.,Ela Malah, Tamer,Thiele, Christina M.,Hecht, Stefan
supporting information; scheme or table, p. 1473 - 1484 (2011/04/15)
Noncovalent interactions, especially hydrogen-bonding interactions as well as electrostatic forces, confined within one macromolecule are the key to designing foldamers that adopt well-defined conformations in solution. In the context of significant recent activities in the area of triazole-connected foldamers, so-called clickamers, we present a fundamental study that compares various model compounds that bear adjacent N-, O-, or F-heteroatom substituents. The interplay of attractive and repulsive interactions leads to rotational constraints around the single bonds attached to both the 1- and 4-positions of the 1,2,3-triazole moiety and should therefore be able to induce well-defined conformational preferences in higher oligomers and polymers, that is, foldamers. Various compounds were synthesized and characterized with regard to their preferred conformations in all three aggregation statesa-that is, in the gas phase, in solution as well as in the solid statea-by employing DFT calculations, NMR spectroscopic experiments, and X-ray crystallography, respectively. On the basis of the thus-obtained general understanding of the conformational behavior of the individual connection motifs, heterostructures were prepared from different motifs without affecting their distinct folding characteristics. Therefore, this work provides a kind of foldamer construction kit, which should enable the design of various clickamers with specific shape and incorporated functionality. A foldamer construction kit: Various heterostructures "clicked" together by structure-directing triazole moieties were investigated with regard to their conformational behavior. Different heteroatoms (X; see graphic) can be used to bias the conformation around the N(1)- and C(4)-connecting single bonds of the triazoles based on tunable noncovalent interactions.
Ethylammonium nitrate (EAN)/Tf2O and EAN/TFAA: Ionic liquid based systems for aromatic nitration
Aridoss, Gopalakrishnan,Laali, Kenneth K.
experimental part, p. 8088 - 8094 (2011/11/13)
Acting as in situ sources of triflyl nitrate (TfONO2) and trifluoroacetyl nitrate (CF3COONO2), the EAN/Tf 2O and EAN/TFAA systems, generated via metathesis in the readily available ethylammonium nitrate (EAN) ionic liquid as solvent, are powerful electrophilic nitrating reagents for a wide variety of aromatic and heteroaromatic compounds. Comparative nitration experiments indicate that EAN/Tf2O is superior to EAN/TFAA for nitration of strongly deactivated systems. Both systems exhibit low substrate selectivity (K T/KB = 5-10) in (Figure presented) between values reported for covalent nitrates and preformed nitronium salts.
Solvent-free synthesis of aryl ethers promoted by tetrabutylammonium fluoride
Xiong, Wei,Ding, Quansheng,Chen, Jiuxi,Ding, Jinchang,Wu, Huayue
experimental part, p. 395 - 398 (2010/11/18)
The reaction of aryl fluorides with silyl reagents has been shown to be efficiently promoted by tetrabutylammonium fluoride, providing aryl ethers with good to excellent yields under solvent-free conditions. The efficiency of this reaction was demonstrate
Regioselective SNAr reactions of substituted difluorobenzene derivatives: practical synthesis of fluoroaryl ethers and substituted resorcinols
Ouellet, Stéphane G.,Bernardi, Anna,Angelaud, Remy,O'Shea, Paul D.
supporting information; experimental part, p. 3776 - 3779 (2009/10/11)
In this Letter, we describe a practical and highly selective method for the preparation of fluoroaryl ethers and differentially substituted resorcinol derivatives. This synthetic strategy relies on a selective SNAr of substituted difluorobenzen
Nitration of some aromatic compounds by sodium nitrate in the presence of benzyltriphenylphosphonium peroxodisulfate
Tajik, Hassan,Zolfigol, Mohammad Ali,Albadi, Jalal,Eslami, Ramin
, p. 2771 - 2776 (2008/02/12)
A simple, mild, and regioselective method for the nitration of some aromatic compounds using sodium nitrate in the presence of benzyltriphenylphosphonium peroxodisulfate in acetonitrile as solvent is reported. Mild reaction conditions and good to excellent yields of the products are the noteworthy advantages of the method. Copyright Taylor & Francis Group, LLC.
Endothelin receptor antagonists
-
, (2008/06/13)
Novel N-phenyl imidazole derivatives, pharmaceutical compositions containing these compounds and their use as endothelin receptor antagonists are described.
Electrophilic tetraalkylammonium nitrate nitration. II. Improved anhydrous aromatic and heteroaromatic mononitration with tetramethylammonium nitrate and triflic anhydride, including selected microwave examples
Shackelford, Scott A.,Anderson, Mark B.,Christie, Lance C.,Goetzen, Thomas,Guzman, Mark C.,Hananel, Martha A.,Kornreich, Wayne D.,Li, Haitao,Pathak, Ved P.,Rabinovich, Alex K.,Rajapakse, Ranjan J.,Truesdale, Larry K.,Tsank, Stella M.,Vazir, Haresh N.
, p. 267 - 275 (2007/10/03)
A new one-pot nitration employing tetramethylammonium nitrate and trifluoromethanesulfonic anhydride in dichloromethane to provide a ready source of the nitronium triflate nitrating agent is presented. Rapid and selective nitration with a variety of aromatic and heteroaromatic substrates is achieved resulting in the synthesis of several novel organic compounds. A distinct advantage is the removal of undesired byproducts by aqueous workup. This very mild nitration permits large-scale syntheses and gives high isolated product yields that often require no further purification. This tetramethylammonium nitrate-based nitration also has been applied to microwave-assisted conditions, and the results with several compounds are outlined.
Further studies of regioselective alkoxydehalogenation of 2,4-dichloroquinolines, 2,6-dichloropyridine and 2,4-dichloronitrobenzene
Osborne, Alan G.,Dimitrova, Galya T.,Galbally, Paul,Hughes, David D.,Jones, Clare,Lipman, Anthony L.,Wilstead, Nicola
, p. 124 - 148 (2007/10/03)
Regioselective alkoxydehalogenation reactions using solid alkoxide in toluene have been studied. 2-Alkoxy-4-haloquinolines were obtained from 2,4-dichloroquinolines. With 2,6-dichloropyridine, α-regioselectivity occurred to furnish the 2-alkoxy-6-chloropyridine. The reaction failed with 2,4-dichloronitrobenzene indicating that alkoxide surface contact with a basic heterocyclic nitrogen lone pair was essential for success. Comparative studies with the standard alkoxydehalogenation reaction (alcoholic alkoxide solution) have been performed, all compounds have been identified by 1H and 13C NMR.
Reactions of 1,2- and 1,3-dimethoxy- and 1,3,5-trimethoxybenzene with nitrogen dioxide/dinitrogen tetraoxide in dichloromethane
Gowenlock, Brian G.,King, Boyd,Pfab, Josef
, p. 276 - 277 (2007/10/03)
The products of reaction of nitrogen dioxide/dinitrogen tetraoxide with dichloromethane solutions of three different methoxybenzenes are studied and interpreted in terms of initial nitrosation followed by oxidation with nitrogen dioxide.
