Large Deuterium Isotope Effects for Intramolecular CH Insertion Reaction of 2-Alkylphenylnitrenes.

The deuterium isotope effect for the intramolecular CH insertion reaction of the nitrene photolytically generated from 2-(2-phenylethyl)phenyl azide in cyclohexane is obtained as 14.7 ± 0.3 at 20 °C, which supports the hydrogen abstraction-recombination mechanism involving the triplet state nitrene. The temperature dependence of the isotope effect suggests the operation of the tunneling of the hydrogen atom in this process.