The Reaction of Diphenylcarbene with Nitroxides

Article abstract of DOI:10.1021/jo00200a040

Diphenylcarbene reacts with 2,2,6,6-tetramethylpiperidine N-oxide with a rate constant of 2.7 x 10⁸ M^-1 s^-1 in acetonitrile at room temperature.The reaction involves the thransfer of an oxygen atom, leading to benzophenone and 2,2,6,6-tetramethylpiperidinyl radical in essentially quantitative yields.In the case of 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxide insertion at the O-H bond competes with reaction at the nitroxide center, with rate constants of 1.9 x 10⁷ and 2.8 x 10⁸ M^-1 s^-1, respectively.The reaction of the OH site is not enhanced significantly by the presence of a paramagnetic center in the molecule.