Gas-phase pyrolysis of 1-(pyrazol-4-yl)-1H-benzotriazoles. Pyrolytic approach to indole and condensed indole derivatives of potential synthetic and biological applications

•Gas-phase pyrolysis of 1-(pyrazol-4-yl)-1H-benzotriazole derivatives.•Pyrolytic direct synthesis of 2-vinyl-1H-indole.•Pyrolytic synthesis of pyrazolo[4,3-b]indoles.•Pyrolytic synthesis of dihydroindolo[3,2-b]carbazole.

Gas-phase pyrolysis of 1-(pyrazol-4-yl)-1H-benzotriazole derivatives offers an alternative good synthetic approach to indole and condensed indole derivatives of potential synthetic and biological applications. The products of thermolysis were investigated, characterized and rate constants were calculated for the gas phase reactions of these compounds. The reactions were found to be homogeneous first-order elimination processes, with Arrhenius log A and Ea values of 10.0-13.5 s−1 and 148-192 kJ mol−1, respectively. The kinetic data and molecular reactivities are explained on the basis of a plausible mechanism involving initial loss of molecular nitrogen leading to the formation of biradical/carbene intermediates.

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