Synthesis of Nitroanilines Catalyzed by Horseradish Peroxidase in the Presence of NaNO2 and H2O2

The synthesis of nitroanilines catalyzed by horseradish peroxidase（HRP） in the presence of sodium nitrite and hydrogen peroxide was investigated, o-Nitroaniline and p-nitroaniline were found in the nitrated products. 2-Aminotoluene and 4-aminotoluene could also be nitrated to give corresponding nitrated products. This protocol has great potentials to open new avenues useful for the synthesis of nitroaniline and its derivatives.     

Synthetic studies of benzo[b]pyrrolo[4,3,2-de][1,10]phenanthroline

6,11-Dihydrobenzo[b]pyrrolo[4,3,2-de][1,10]phenanthroline-5,8-dione (6), which possesses a unique heterocyclic ring system similar to that in plakinidines A-D (1-4), was synthesized from 2-acetyl-3′-nitrodiphenylamine (16) in nine steps.     

硝基苯的制备及废硫酸回收利用的研究

苯在四氯化碳溶剂中以硝酸和疏酸的混合酸为硝化剂在温和条件下进行硝化，硝基苯的产率高，硫酸可以回收再利用。例如，在带有搅拌器、滴液漏斗、温度计和冷凝器的四颈烧瓶中，加入４４．４毫升苯和４０毫升四氯化碳，将３９．５毫升浓硝酸和４１．５毫升浓硫酸混合后从滴液漏斗中滴加，维持温度在１５～５５℃之间，约４０分钟滴完后，在５５～６２℃继续反应３０分钟。有机层分别用水、１０％氢氧化钠溶液、水洗涤，干燥、蒸馏，先蒸出溶剂可再用。然后收集２０４～２１０．８℃的馏份，得硝基苯６０．６克，产率９８．５３％。废硫酸通过蒸馏浓缩后，可重新用于硝化反应。     

Tricyclic heteroaromatic ring systems IV. Synthesis and reactions of 4H-Pyrazolo[1,5-a]benzimidazole

The 4H-Pyrazolo[1,5-a]benzimidazole ring system was prepared by an intramolecularUllmann arylation of 4-substituted 1-(o-aminophenyl)pyrazole while other derivatives were obtained by functional group modifications. Some electrophilic substitutions (nitration, bromination) and alkylations were also carried out.

---

Tricyclische heteroaromatische Ringsysteme, 4. Mitt.: Synthese und Reaktionen von 4H-Pyrazolo[1,5-a]benzimidazolen

Zusammenfassung Das 4H-Pyrazolo[1,5-a]benzimidazol-System wurde mittels intramolekularerUllmann-Arylierung von 4-substituierten 1-(o-Aminophenyl)pyrazolen hergestellt; weitere Derivate wurden dann durch Modifikation funktioneller Gruppen synthetisiert. Einige elektrophile Substitutionen (Nitrierung, Bromierung) und Alkylierungen wurden ebenfalls durchgeführt.

     

Highly chemoselective nitration of aromatic amines using the Ph3P/Br2/AgNO3 system

The use of PPh₃/Br₂/AgNO₃ provides a new reagent system for the novel and highly chemoselective nitration of aromatic amines under mild reaction conditions.     

Reactivity of pyrrole pigments. Part 5: Electrophilic substitution—Nitration and bromination—Of some pyrromethenones and 5-arylmethylene-3,4-dimethyl-3-pyrrolin-2-ones

Some 5-arylmethylene-3,4-dimethyl-3-pyrrolin-2-ones react with both bromine and nitronium tetrafluoroborate (NO₂BF₄) to give 5-(aryl)nitromethylene-3-pyrrolin-2-ones and 5-(aryl)bromomethylene-3-pyrrolin-2-ones, respectively. The use of bromine in methanol affords 5-(aryl)bromomethyl-3,4-dimethyl-5-methoxy-3-pyrrolin-2-ones. Whereas pyrromethenones react mainly on the pyrrole ring, ethyl 3,4-demethyl-5-[(3,4-dimethyl-5-oxo-3-pyrrolin-2-yl)methylene]-1H-pyrrole-2-carboxylate reacts as the aryl derivatives, however, with bromine in methanol the addition of two methoxy groups at the exocyclic double bond takes place. 3,4-Dimethyl-5-(2-pyridylmethylene)-3-pyrrolin-2-one does not react with bromine or NO₂BF₄, but reacts as the aryl derivatives with bromine in methanol. The reactivity patterns are in agreement with the theoretical ones obtained from MINDO/3 calculations, using theFukui frontier orbital model. The obtained results are used to explain the reactivity of rubins (biladienes-a,c) and verdins (bilatrienes-a,b,c) in front of electrophiles.Einige 5-Arylmethylen-3,4-dimethyl-3-pyrrolin-2-one reagieren sowohl mit Brom als auch mit Nitroniumtetrafloroborat (NO₂BF₄). Man erhält 5-(aryl)bromomethylen-oder 5-(aryl)nitromethylen-3-pyrrolin-2-one. Bei Verwendung einer methanolischen Bromlösung werden 5-(aryl)bromomethyl-3,4-dimethyl-5-methoxy-3-pyrrolin-2-one gebildet. Pyrromethenone reagieren hauptsächlich am Pyrrolring, Ethyl 3,4-dimethyl-5-[(3,4-dimethyl)-5-oxo-3-pyrrolin-2-yl)methylen]-1H-pyrrol-2-carboxylat hingegen verhält sich wie ein Arylderivat, mit methanolischen Bromlösung jedoch erfolgt Eintritt zweier Methoxygruppen an der exocyclischen Doppelbindung.5-(2-Pyridyl)methylen-3,4-dimethyl-3-pyrrolin-2-on reagiert nicht mit Brom oder NO₂BF₄, wohl aber mit einer methanolischen Bromlösung und verhält sich unter diesen Bedingungen wie ein Arylderivat; 3- und 4-Pyridylderivate verhalten sich analog. Die Reaktivität ist in Übereinstimmung mit theoretischen Werten aus MINDO/3-Rechnungen unter Verwendung des Fukui frontier orbital model. Die Reaktivität von Rubinen (Biladiene-a, c) und Verdinen (Bilatriene-a,b,c) gegenüber Elektrophilen werden im Zusammenhang mit den erhaltenen Resultaten diskutiert.

---

Reaktivität der Pyrrolpigmente, 5. Mitt.: Elektrophile Substituierung (Nitrierung und Bromierung) von einigen Pyrromethenonen und 5-Arylmethylen-3,4-dimethyl-3-pyrrolin-2-onen

     

Synthesis of Oxidized Derivatives of 10-Deuterobenzo[A]Pyrene

A series of oxidized derivatives of 10-deuterobenzol[a]pyrene (10-D-BaP) were synthesized. Oxidation of 10-D-BaP with sodium dichromate dihydrate yielded the 1,6-, 3,6-, and 6,12-quinones of 10-D-Bap. Upon electrophilic aromatic substitution of 10-D-BaP with sodium nitrate, N-bromosuccinimide, and N-chlorosuccinimide we were afforded 6-nitro-10-D-BaP, 6-bromo-10-D-BaP, and 6-chloro-10-D-BaP, respectively, in high yields. The Vilsmier-Haack reaction of 10-D-BaP provided 6-formyl-10-D-BaP which upon reduction with sodium borohydride, yielded 6-hydroxymethyl-10-D-BaP. Reduction with hydrazine in n-amyl alcohol gave 6-methyl-10-D-BaP. Reduction of 6-nitro-10-D-BaP with hydrazine and Pd/C yielded 6-amino-10-D-BaP. The synthesized compounds, which are known metabolites of benzo[a]pyrene and are useful substrates for metabolism, are important compounds for mechanistic study of the chemical carcinogenesis by benzo[a]pyrene.     

Synthesis,characterization of Nafion-functionalized MCM-41 and its catalytic application in preparation of CL-20 via HNO3 electrolyte involved nitration of TAIW

Hybrid organic–inorganic MCM-41 (Mobil Composition of Matter No. 41) silicas functionalized with Nafion (perfluoroalkylsulfonic acid analogous) were prepared and characterized by Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and N₂ adsorption analysis. The Brønsted acidity was determined by UV spectrophotometer. The prepared catalyst (SA/MCM-41) exhibited high catalytic activity in the nitration of TAIW (tetraacetylhexaazaisowurtzitan) aiming at synthesizing CL-20 (hexanitrohexaazaisowurtzitane), with the yield up to 93%. The leaching problem was not observed after several runs, demonstrating that the catalyst could be recycled and reused without losing activity.     

Electrophilic Nitration of Electron-Rich Acetophenones

Summary. It is demonstrated that electron-rich disubstituted acetophenones react according to various electrophilic nitration conditions that generally lead to ipso substitution accompanying the conventional reaction. The hydroxy substituent does not seem prone to favor such behaviour.