Triphenylpyrylium salt-sensitized photoreactions of 1,4-diaryl-2,3-dioxabicyclo[2.2.2]octanes through competitive single electron-transfer pathway and proton-catalyzed pathway

Cyclization–endoperoxidation cascade reactions of dienes mediated by a pyrylium photoredox catalyst

“…For these reasons, we were attracted to the use of triarylpyrylium salts, as they have excited state reduction potentials in excess of +1.7 V vs SCE ( Scheme 2 ) [ 20 ]. In addition, prior work demonstrates that these catalysts are productive in cation radical mediated [4 + 2], [2 + 2], oxygenation, and rearrangement chemistry [ 21 – 22 ]. We also sought to delineate the reactivity of the diene with respect to its structure to better predict the mode of diene cation radical cyclization (5- exo vs 6- endo ).…”

Synthesis and Chemistry of 2,3-Dioxabicyclo[2.2.2]octane-5,6-diols

“…In addition to the use of 2,3-dioxabicyclo[2.2.2]octane-5,6-diols 4 for the synthesis of cyclohexane-1,2,3,4-tetraols 5 , the synthesis of a broad range of substituted compounds of type 4 also provided us with the opportunity to investigate an underexplored area of 2,3-dioxabicyclo[2.2.2]oct-5-ene chemistry. Thermal, − metal catalyzed, , and photo-induced electron-transfer-assisted , decomposition of bicyclic endoperoxides have been extensively studied; however, no such possible transformations have been investigated for 2,3-dioxabicyclo[2.2.2]octane-5,6-diol substrates. Consequently, we report herein new studies on the thermal and photochemical decomposition of systems of type 4 for the ready construction of 1,4-dicarbonyl derivatives.…”

Efficient Photocatalytic Oxygenation of Aromatic Alkene to 1,2-Dioxetane with Oxygen via Electron Transfer

“…The SOMO (singly occupied molecular orbital) of dioxetane radical cation involves O−O σ antibonding orbital (Figure b). This may be the reason for the facile cleavage of the O−O bond of the dioxetane radical cation 4 (a) ESR spectrum of TPE dioxetane radical cation observed under irradiation of a deaerated CHCl 3 solution containing TPE dioxetane (3.0 × 10 -3 M) and Acr + -Mes (3.7 × 10 -2 M) at 223 K measured at 143 K (frozen).…”