Divergent reactivity of triflones: competing epoxidation and olefination pathways with formaldehyde

alpha-Substituted benzylic triflones exhibit chameleonic reactivity when treated with formaldehyde in the presence of 1,5,7-triazabicyclodec-5-ene (TBD), enabling divergent reaction pathways controlled by substrate structure. Depending on the substitution pattern, a practical and operationally simple protocol delivers either 2,2-disubstituted epoxides or electron-deficient styrenes in good to excellent yields. Computational investigations provide predictive insight into the reaction outcome, revealing a competition between SN2 and Horner-Emmons like pathways. The structure of the triflone governs the selectivity, offering a rational framework to anticipate product formation. By leveraging the dual role of the triflone group as both an electron-withdrawing and a leaving group, this study expands the synthetic utility of triflones, highlighting their ylide-like behavior.