Nitration in the carbazole series

Nitration of9-tosylcarbazole in acetic anhydride solution gives l-nitro (28%), 2-nitro (19%) and 3-nitro (53%) derivatives. The mixture of the nitro compounds obtained from 9-acetylcarbazole contains 10%, 48% and 42% of the isomers, respectively. Under similar conditions 9-nitrosocarbazole shows a different isomer distribution: 34% of 1-nitro and 66% of 3-nitrocarbazole. Nitration of carbazole is a two step process involving formation and rearrangement of 9-nitrocarbazole. The hypothesis was supported by the results of 1,3,6,8-tetrachlorocarbazole nitration and oxidation of 9-nitrosocarbazole and rearrangement of 9-nitrocarbazole in the nitration conditions.     

Synthesis of monothiooxamides of the thiazole series

A convenient method for the synthesis of previously inaccessible monothiooxamides of the thiazole series was developed. The method is based on the reaction of pyridinium salts obtained from 2-(chloroacetylamino)thiazole and pyridine with a solution of elemental sulfur and amines prepared beforehand.     

Some tetra-substituted ammonium salts of the thiazole series

A series of monomethiodides of 2-amino(or 2-methyl- and 2-phenyl)-4-(N-cycloalkylamino)methylthiazoles are synthesized. It is shown that in these compounds the nitrogen atom of the cycloalkylamino group is quaternized.     

Some tetra-substituted ammonium salts of the thiazole series

A series of monomethiodides of 2-amino(or 2-methyl- and 2-phenyl)-4-(N-cycloalkylamino)methylthiazoles are synthesized. It is shown that in these compounds the nitrogen atom of the cycloalkylamino group is quaternized.     

Nitration in the imidazo[1,2-a]pyrazine series. Experimental and computational results

Nitration was carried out on a series of imidazo[1,2-a]pyrazine derivatives. The reactivities of diversely substituted derivatives and of all positions of substitution were analysed and experimental results compared with ¹³-nmr data and semi empirical calculations (AMI). Although the unsubstituted heterocycle is highly resistant to nitration, electron-donating groups such as alkoxy or alkylamino on position 8 enhance the reactivity of the imidazo[1,2-a]pyrazine derivatives towards electrophilic substitution and, more specifically, nitration. The ¹³-nmr experiments, electronic distributions and Molecular Electrostatic Potential isodensity surfaces calculated on the neutral forms are in good agreement with experimental results indicating position 3 is the most reactive position towards nitration.     

Nitration of 2- and 4-[2-(2-furyl)vinyl]thiazole derivatives

Nitration of 4-methyl-2-[2-(nitro-2-furyl)vinyl]thiazole with a mixture of concentrated nitric and sulfuric acids leads to 4-methyl-5-nitro-2-[2-(3,5-dinitro-2-furyl)vinyl]thiazole. Under the same conditions 2-methyl- and 2-acetamido-4-[1-R-2-(5-nitro-2-furyl)vinyl]thiazoles (R=CH₃, Cl) are nitrated in the 3 position of the furan ring, 2-amino-4-[1-chloro-2-(5-nitro-2-furyl)vinyl]thiazole is nitrated in the 5 position of the thiazole ring and 2-acetamido-5-nitro-4-[2-(2-furyl)vinyl]thiazole undergoes profound changes. Under the influence of a mixture of of nitric acid and acetic anhydride the latter compound is converted quantitatively to the 5-nitro derivative (with respect to the furan ring), whereas 4-[2-(5-nitro-2-furyl)vinyl]thiazole derivatives do not undergo reaction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 314–317, March, 1977.     

Nitro derivatives of the thiophene series. 2. Nitration of thienyl-substituted unsaturated methyl ketones

The nitration of 4-(5-R-2-thienyl)-3-buten-2-ones with nitric acid in acetic anhydride is accompanied by the formation of a mixture of nitro isomers, whereas nitration with nitric acid and copper and aluminum nitrates in carbon tetrachloride, dichloroethane, and acetonitrile leads to the production of only the -nitro ketone. The results of quantum-chemical calculations of the reactivity indexes within the CNDO/2 approximation are in agreement with the experimental data on electrophilic substitution of these compounds in the basic and protonated forms.See [1] for Communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 325–328, March, 1981.     

Das Nitration

Ohne Zusammenfassung     

Nitro derivatives of the thiophene series. 4. Nitration of thiophene derivatives with metal nitrates in acetic anhydride

The nitration of 2-formylthiophene, 2-acetothienone, and unsaturated ketones of the thiophene series with copper and aluminum nitrates in acetic anhydride at various temperatures was studied. At low temperatures 2-acetothienone gives a mixture of 4- and 5-nitro isomers, while 2-formylthipphene gives only a 5-nitro-substituted compound in the diacetate form; ,-unsaturated ketones are not nitrated under these conditions. When the reaction is carried out at 70–90 °C, one can obtain mixtures of nitro ketones in the case of unsaturated ketones; 2-formylthiophene is oxidized to thiophene-2-carboxylic acid, while 2-acetothienone gives a substance, the structure of which could not be established. The reaction of copper and aluminum nitrates with acetic anhydride was investigated by means of thermal and x-ray diffraction analysis. It is shown that the reaction is accompanied by the formation of free nitric acid, and the nitrating agent in these mixtures is consequently the nitronium cation.See [1] for communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 913–916, July, 1981.     

Synthesis of oligonucleotides containing thiazole and thiazole N-oxide nucleobases

[reaction: see text] The thiazole C-nucleoside analogue was synthesized by the Hantzsch cyclization method to form the thiazole ring and was then converted to the thiazole N-oxide C-nucleoside analogue by peracid oxidation of the heterocycle nitrogen. Incorporation of the thiazole and thiazole N-oxide phosphoramidites into DNA was successful though significant deoxygenation of the N-oxide occurred during DNA assembly. The mechanism proposed for the reduction of the thiazole N-oxide to thiazole involves the formation of an N-oxide phosphite ester.     

Nitration of tetrabenzoporphins

Zinc meso-trinitrotetrabenzoporphin and zinc meso-tetranitrotetrabenzoporphin were obtained by nitration of zinc tetrabenzoporphin and its tert-butyl-substituted analog with a mixture of nitric and acetic acids. A demetallated compound is formed in 88% yield when zinc meso-tetranitrotetrabenzoporphin is treated with HCl in acetic acid, and reduction of the nitro groups to amino groups occurs when it is treated with tin in acetic acid.The authors thank T. A. Babushkina (Institute of Biophysics, Ministry of Public Health of the USSR) for recording the PMR spectrum of III and assisting in its interpretation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1189–1193, September, 1986.     

Nitration of N-Alkyl-N'-nitroureas

Russian Journal of Organic Chemistry -     

Nitration of carboxymethylcellulose

The influence of the conditions of nitration and the structure of the initial carboxymethylcellulose on the depth of conversion and the molecular characteristics of the nitroesters obtained has been investigated. The products obtained after optimization of the hydrophilic-hydrophobic balance with the aim of imparting solubility to them possess a pronounced antianginal action.A. S. Sadykov Institute of Biochemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, FAX (3712) 62-70-71. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 544–546, July–August, 1994.     

蛋白质酪氨酸硝化的研究

蛋白质酪氨酸硝基化是一种重要的蛋白质翻译后修饰,与多种病症相关。经由过氧亚硝酸根（ONOO-）和NO2^-／H2O2／血红素过氧化物酶体系是促使蛋白质硝化最主要的两种途径,其反应为自由基机理。本文对体内蛋白质硝基化的途径、机制及其生物学意义作了综述,指出蛋白质的硝化具有选择性,特定酪氨酸残基发生硝化能够改变蛋白质的结构和功能,影响其免疫应答和可能涉及的信号转导过程,从而具有重要的生物学意义。     

Nitration of carboxymethylcellulose

The possibility has been shown of using hydrolytic splitting to regulate the degree of polymerization and the molecular and compositional homogeneity of carboxymethylcellulose, which makes it suitable for the production of medico-biological polymers. A. S. Sadykov Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, FAX (3712) 62-70-71. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 541–544, July–August, 1994.     

蛋白质酪氨酸硝化的研究

蛋白质酪氨酸硝基化是一种重要的蛋白质翻译后修饰,与多种病症相关。经由过氧亚硝酸根(ONOO-)和NO2-/H2O2/血红素过氧化物酶体系是促使蛋白质硝化最主要的两种途径,其反应为自由基机理。本文对体内蛋白质硝基化的途径、机制及其生物学意义作了综述,指出蛋白质的硝化具有选择性,特定酪氨酸残基发生硝化能够改变蛋白质的结构和功能,影响其免疫应答和可能涉及的信号转导过程,从而具有重要的生物学意义。