616-72-8Relevant academic research and scientific papers
Nitration of deactivated aromatic compounds via mechanochemical reaction
Wu, Jian-Wei,Zhang, Pu,Guo, Zhi-Xin
supporting information, (2021/05/05)
A variety of deactivated arenes were nitrated to their corresponding nitro derivatives in excellent yields under high-speed ball milling condition using Fe(NO3)3·9H2O/P2O5 as nitrating reagent. A radical involved mechanism was proposed for this facial, eco-friendly, safe, and effective nitration reaction.
Synthesis and Electronic Properties of Novel 5,7-Diazapentacene Derivatives
Lunchev, Andrey V.,Morris, Samuel A.,Ganguly, Rakesh,Grimsdale, Andrew C.
, p. 1819 - 1823 (2019/01/14)
A route to the synthesis of novel 5,7-diazapentacenes and some preliminary studies on their properties is reported. A single crystal X-ray diffraction study of the dihexyl derivative showed it had formed a dimer during the analysis. The materials possess lower lying frontier orbitals than pentacene and may have potential applications in organic electronic devices. This synthetic method may be applicable to the synthesis of other azaacenes.
Design and synthesis of urea-linked aromatic oligomers-a route towards convoluted foldamers
Mousseau, James J.,Xing, Liyan,Tang, Nathalie,Cuccia, Louis A.
supporting information; experimental part, p. 10030 - 10038 (2010/06/15)
Herein we report the design and synthesis of crescent-shaped and helical urea-based foldamers, the curvature of which is controlled by varying the constituent building blocks and their connectivity. These oligomers are comprised of two, three or five alternating aromatic heterocycles (pyridazine, pyrimidine or pyrazine) and methyl-substituted aromatic carbocycles (tolyl, o-xylyl or m-xylyl) connected together through urea linkages. A crescent-shaped conformational preference is encoded within these π-conjugated urea-linked oligomers based on intramolecular hydrogen bonding and steric interactions; the degree of curvature is tuned by the urea connectivity to the heterocycles and the aryl groups. NMR characterization of these foldamers confirms the intramolecular hydrogen-bonded conformation expected (Z,E configuration of the urea bond) in both the pyridazyl and pyrimidyl foldamers in solution. An X-ray crystal structure of the N3,N6-diisobutylpyridazine-4,6- diamine-o-tolyl urea-linked foldamer (4) confirms the presence of N-H...N hydrogen bonds between the heterocyclic nitrogen atom and the free hydrogen of the urea linkage. Additionally, the tolyl methyl group interacts unfavourably with the urea carbonyl oxygen, thus destabilising the alternate planar conformation.
Synthesis and characterization of 2,7-bis(2-pyridyl)-1,8-diazaanthraquinone - A redox-active ligand designed for the construction of supramolecular grids
Jain, Rajsapan,Caldwell, Sharon L.,Louie, Anika S.,Hicks, Robin G.
, p. 1263 - 1267 (2008/01/27)
Double condensation of 2-acetylpyridine with 1,3-diaminobenzene-4,6- dicarboxaldehyde affords 2,7-bis(2-pyridyl)-1,8-diazaanthracene, which was subsequently oxidized to the corresponding quinone. Electrochemical studies indicate two reversible reduction processes corresponding to semiquinone and hydroquinonate formation. Electron-withdrawing pyridine groups and the nitrogen atoms make this somewhat more easily reduced than anthraquinone. This compound is redox-active and can be reduced to its radical anion, a potential spin-bearing ligand for the construction of [2 x 2] metallo-grid structures.
Overcoming regioselectivity issues inherent in bis-Troeger's base preparation
Havlik, Martin,Kral, Vladimir,Dolensky, Bohumil
, p. 4867 - 4870 (2007/10/03)
(Figure Presented) Bis-Troeger's base derivatives are a new family of molecular tweezers. A major drawback to their study is a lack of commercially available precursors, ortho-nitrocarboxylic acids. A reverse synthetic strategy starting from known dinitrodicarboxylic acids, which circumvents this problem, is presented. Via this methodology regioisomeric bis-TB derivatives can be prepared selectively, using only common aromatic amines that are typically commercially available.
Aromatic oligoureas: Enforced folding and assisted cyclization
Zhang, Aimin,Han, Yaohua,Yamato, Kazuhiro,Zeng, Xiao Cheng,Gong, Bing
, p. 803 - 806 (2007/10/03)
Aromatic oligoureas are forced into well-defined conformation by incorporated intramolecular hydrogen bonds. Shape-persistent tetraureas macrocycles were obtained in a one-step [2 + 2] reaction in good yields.
Thermal Stability Studies on a Homologous Series of Nitroarenes
Oxley, Jimmie C.,Smith, James L.,Ye, Hong,McKenney, Robert L.,Bolduc, Paul R.
, p. 9593 - 9602 (2007/10/02)
The thermal stabilities of a number of nitroarenes were examined in solution and in condensed phase.In general, increasing the number of nitro groups decreased thermal stability.Changing the substituent on 1-X-2,4,6-trinitrobenzene from X = H to NH2 to CH3 to OH accelerated decomposition; this effect was attributed to increased ease of intramolecular proton transfer to an ortho nitro group, thus weakening the carbon-nitrogen bond.In solution, the effect of increasing substitution from n = 1 to n = 3 on Xn(NO2)3C6H3-n was uniformly that of decreasing the thermal stability of the species.However, in condensed phase, results suggested that crystal habit may be more important than molecular structure; for X = Br, CH3, and NH2, the more substituted species was the more stable.
Ozone-mediated Nitration of Alkylbenzenes and Related Compounds with Nitrogen Dioxide
Suzuki, Hitomi,Murashima, Takashi,Kozai, Iku,Mori, Tadashi
, p. 1591 - 1598 (2007/10/02)
In the presence of ozone, nitrogen dioxide exhibits a strong nitrating ability for alkylbenzenes at low temperatures, converting them into the corresponding nitro derivatives in high yield.The addition of a protonic acid as catalyst enhances considerably the ability of this nitrating system and leads to a good yield of polynitro compounds.The reaction is clean and proceeds rapidly without any accompanying side-chain substitution or aryl-aryl coupling.It shows no kinetic dependence on the concentration of substrates and, as far as can be judged from relative reactivities and isomer distributions of products, it gives the appearance of being an electrophilic aromatic process.A possible role for nitrogen trioxide has been suggested as the initial electrophilic agent for the nitration of alkylbenzenes.
Synthesis and Reactions of Some Pyridoquinolines (1,8-Diazaanthracenes)
Quast, Helmut,Schoen, Norbert
, p. 133 - 146 (2007/10/02)
The pyridoquinolines 1b, c, and e are synthesized for the first time directly by Friedlaender condensation from 4,6-diaminoisophthalic aldehyde (6) and ketones.Copper(I)-catalyzed decarboxylation of the 2,8-dicarboxylic acid 1e occurs in diethylene glycol monoethyl ether at temperatures as low as 165 deg C affording the parent compound 1a in high yield.Despite steric hindrance by a tert-butyl group methyllithium adds to position 2 of the 2,8-di-tert-butyl compound 1c producing the 1,2-dihydropyridoquinoline 9.Dehydrogenation of the octahydroquinoacridine 7 using palladium on carbon at 250 deg C yields the 1,2,3,4,7,12-hexahydro- (10) and the 5,14-dihydroquinoacridine (11).
Cycloarenes, a New Class of Aromatic Compounds, I. Synthesis of Kekulene
Staab, Heinz A.,Diederich, Francois
, p. 3487 - 3503 (2007/10/02)
Definition and nomenclature of cycloarenes, a new class of aromatic compounds, are discussed.Cyclododecakisbenzene ("kekulene", 1) has been synthesized as the first representative of cycloarenes. - From the dithiaphane 11 by double sulfur extrusion, either photochemically or by pyrolysis of disulfone 12, the carbocyclic system 13 was formed which by dehydrogenation yielded 14.By Stevens rearrangement of 11 followed by elimination the phanediene 15 was obtained which was dehydrogenated to 18.From 15 by photo-cyclodehydrogenation in excellent yield the octahydrokekulene 19 was obtained.The different reactivity of 15 and 18 in the photo-cyclodehydrogenation is discussed in terms of electronic and steric effects.Dehydrogenation of 19 yielded 1.
