65753-83-5Relevant academic research and scientific papers
Competitive Cyclisations of Singlet and Triplet Nitrenes. Part 8. The 1-(2-Nitrenophenyl)pyrazoles and Related Systems
Lindley, John M.,McRobbie, Ian M.,Meth-Cohn, Otto,Suschitzky, Hans
, p. 982 - 994 (2007/10/02)
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.
