Fig. 3. UV-vis spectra for the reaction of 2a (prepared by reaction of 1a with (p-tolyl)₃N⁺˙) with ^NO₂ArOH in THF at –80 °C. (Black) Initial spectrum of 2a. (Grey) Intermediate spectra as a function of time (4–834 s). (Blue) Final spectrum stable at –80 °C. (Red) Spectrum resulting from warming to room temperature.