4-N,N-Dimethylaminophenyl azide photooxidation: effect of conditions on the reaction pathway. Ring contraction of benzene to cyclopentadiene due to a strongly electron-donating substituent

Conformational Transformations in Aromatic Nitroso Oxides

“…ArNOO decay occurs in quite a different way in polar acetonitrile at room temperature. This follows from the considerable growth of effective rate constants, the strong decrease in the activation energies of consumption of both isomers, , and the change in the ArNOO transformation products studied previously . It was found in the study referred to that Me 2 NC 6 H 4 ­NOO was converted to the corresponding nitro and nitroso compounds under the conditions specified, and almost no products of intramolecular cyclization by the mechanism shown in Scheme were observed.…”

“…The effective first order with respect to the concentrations of Me 2 NC 6 H 4 ­NOO isomers noted previously , undoubtedly deserves an explanation. Presumably, it results from the parallel consumption of nitroso oxide through first- and second-order reactions, the ratio of which, apart from the factors noted above (temperature, solvent), is also affected by the concentration of the starting azide and the intensity of reaction mixture irradiation …”

“…This follows from the considerable growth of effective rate constants, the strong decrease in the activation energies of consumption of both isomers, 14,39 and the change in the ArNOO transformation products studied previously. 29 It was found in the study referred to that Me 2 NC 6 H 4 NOO was converted to the corresponding nitro and nitroso compounds under the conditions specified, and almost no products of intramolecular cyclization by the mechanism shown in Scheme 2 were observed. The conclusion was made that nitroso oxide decay followed a bimolecular mechanism, which explained the observed low activation energy.…”

“…Presumably, it results from the parallel consumption of nitroso oxide through first-and second-order reactions, the ratio of which, apart from the factors noted above (temperature, solvent), is also affected by the concentration of the starting azide and the intensity of reaction mixture irradiation. 29 Conformational Transitions in ortho-Substituted Phenylnitroso Oxides. The chemical potential of aromatic nitroso oxides is so high that they can undergo intramolecular transformation (Scheme 2) accompanied by destruction of the stable aromatic system.…”

“…The latter may be stable enough to be isolated or undergoes further intramolecular rearrangement. The reaction gives carbo- and heterocyclic compounds with various structures, depending on the electronic nature of substituent and its position in the aromatic ring of the nitroso oxide. − Note that only the cis form of phenyl nitroso oxide undergoes this reaction.…”