- Regioselective synthesis of 4-halo ortho-dinitrobenzene derivatives
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A novel method for the regioselective synthesis of 4-halo ortho- dinitrobenzene derivatives was developed by reacting various meta-halo nitrobenzenes with urea nitrate in concentrated sulfuric acid. (C) 2000 Elsevier Science Ltd.
- Mundla, Sreenivasa R.
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p. 4277 - 4279
(2007/10/03)
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- Competitive Cyclisations of Singlet and Triplet Nitrenes. Part 8. The 1-(2-Nitrenophenyl)pyrazoles and Related Systems
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The title nitrenes, derived by nitro-group deoxygenation with triethyl phosphite or by thermolysis or photolysis of the corresponding azide, have been studied.The effect of substituents (Cl, Br, OMe, NMe2, Me, CF3, and NO2) both meta and para to the nitrene has been examined as a determinant of the preferred mode of cyclisation to either a pyrazolobenzotriazole or a pyrazoloquinoxaline.Similarly, the role of solvents, sensitisers, and quenchers has been studied.Routes to the isomeric 1- and 2-(2-nitrophenyl)-4,5,6,7-tetrahydroindazoles have been defined and the literature corrected by studing the nitrene-mediated cyclisation of these products.The chemistry of the analogous 1-(2-carbenophenyl)- and the 1-(2-nitrenosulphonylphenyl)-3,5-dimethylpyrazoles has also been examined, the former giving 2-(3,5-dimethylpyrazol-1-yl)-benzaldazine and -benzyl alcohol while the latter gave products of intramolecular nitrene attack (a pyrazolobenzothiatriazine) and intermolecular reaction.Rationalisations for all the reaction pathways have been advanced.
- Lindley, John M.,McRobbie, Ian M.,Meth-Cohn, Otto,Suschitzky, Hans
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p. 982 - 994
(2007/10/02)
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