Stability and Cyclization of Enol Radical Cations: A Mechanistic Study of One‐Electron Oxidation of β,β‐Dimesityl Enols

A reversal in the position of the keto/enol equilibrium through one-electron oxidationa —a phenomenon already observed in the gas phase—has now also been verified in solution. The ΔG° values (1˙⊕ → 2˙⊕) for the two enols 1 (R = tBu, H) are −17.7 and −25.7 kcal mol−1. Benzofurans 2 are obtained as reaction products from the radical cations in over 80% yield.