Pd-catalyzed C-H activation/C-N bond formation: A new route to 1-aryl-1H-benzotriazoles
A method for the C-H activation of aryl triazene compounds followed by intramolecular amination is described. It involves the use of a catalytic amount of Pd(OAc)2 that efficiently effects the cyclization to provide 1-aryl-1H-benzotriazoles at moderate temperature.
The title molecule, C12H9N5O4, has trans geometry about the azo linkage. The dihedral angle between the two phenyl rings is 6.2(2)°. The whole molecule is almost planar and the maximum deviation from the mean plane is 0.166 (3) A. The resonance effect in the triazene group which might explain the antitumour activity of some triazene derivatives is discussed. In the crystal structure, while the twofold screw-related molecules are packed in a simple herringbone pattern, the inversion-centre-related molecules form hydrogen-bonded dimers which are held together through π...π interactions along the [010] direction.
Na3Co(NO2)6 has been investigated as a new reagent for the nitrosation of various substrates containing an amino functionality. Reactions took place in an aqueous solution of the reagent. The pH of the reaction mixture remained in the range 4.3-5. Thus, hydrazides were transformed to the corresponding acyl azides, and the reactions with arenesulfonyl hydrazines afforded arenesulfonyl azides. Treatment of aromatic amines with Na3Co(NO2)6 gave 1,3-diaryltriazenes in excellent yields; coupling of the initially formed diazo compound to the electron rich aromatic ring was also observed. Nitrosation of aliphatic amines was not possible due to complex formation with the reagent.
Stefane, Bogdan,Kocevar, Marijan,Polanc, Slovenko
p. 7165 - 7169
(2007/10/03)
SUBSTITUENT EFFECT ON SOLVOLYSIS OF 3-ACETYL-1,3-DIPHENYLTRIAZENES
Eleven symmetrically disubstituted 3-acetyl-1,3-diphenyltriazenes have been synthetized by a new method.The solvolysis kinetics of title compounds has been measured in 20percent aqueous ethanol at several temperatures.The results are discussed from the point of view of temperature and substituent effects on the solvolysis rate constant of the 3-acetyl-1,3-diphenyltriazenes and conclusions are drawn about the reaction mechanism.
Pytela, Oldrich,Pilny, Miroslav,Vecera, Miroslav
p. 1173 - 1181
(2007/10/02)
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