Endoperoxide formation

If singlet oxygen is formed by an energy transfer reaction from excited diphenylanthracene to oxygen, the quantum yield of which is the quantum yields of endoperoxide formation are given by... 

Moreover, anthracene UV and IR bands decrease along the reaction because of an anthracene endoperoxide formation (Fig. lb,c). 

Seip M, Brauer H-D. Endoperoxide formation of helianthrene with triplet molecular oxygen. A spin-forbidden reaction. J Am Chem Soc 1992 114 4486-4490. 

Clennan, E.L. and Mohrsheikh-Mohammadi, M.E. (1984) Mechanism of endoperoxide formation. 3. Utilization of the Young and Carlsson kinetic techniques. Journal of the American Chemical Society, 106 (23), 7112-7118. 

Sheu, C. and Foote, C.S. (1993) Endoperoxide formation in a guanosine derivative. Journal of the American Chemical Society, 115 (22), 10446-10447. 

The oxidation of furans has often been used to express the latent functionality present within this heterocyclic framework, and it results particularly attractive for the synthesis of the widespread butenolides [8c,56]. Dye-sensitized photo-oxygenation of furfural, furoic acid and a- or a,a -unsubstituted furans leads directly to butenolides [8c,56,60d,63]. The presence of a silyl group in a-position enhances the rate of endoperoxide formation and controls the regiochemical outcome of the second-step leading to the related butenolide via a rapid intramolecular silatropic shift [64]. An application of this reaction is shown in Sch. 39 as a step in the synthesis of spongianolide A, an antitumoral natural sestertepenoid [65],... 

Alder endopeioxide product. These results are discussed by the authors in terms of failure to meet the steric requirement for endoperoxide formation. ... 

Figure 7.55. Orbital correlation diagram for endoperoxide formation.

Polyelectrolytes and soluble polymers containing triarylamine monomers have been applied successfully for the indirect electrochemical oxidation of benzylic alcohols to the benzaldehydes. With the triarylamine polyelectrolyte systems, no additional supporting electrolyte was necessary [91]. Polymer-coated electrodes containing triarylamine redox centers have also been generated either by coating of the electrode with poly(4-vinyltri-arylamine) films [92], or by electrochemical polymerization of 4-vinyl- or 4-(l-hydroxy-ethyl) triarylamines [93], or pyrrol- or aniline-linked triarylamines [94], Triarylamine radical cations are also suitable to induce pericyclic reactions via olefin radical cations in the form of an electron-transfer chain reaction. These include radical cation cycloadditions [95], dioxetane [96] and endoperoxide formation [97], and cycloreversion reactions [98]. 

The papers on simple alkenes [151] and enol ethers [152] discussed above brought the possibility of exciplex intermediacy to the attention of singlet oxygen chemists and since then several papers concerned with reactions involving allylic hydroperoxide, dioxetane and/or endoperoxide formation have invoked their participation [157-165], some as the sole intermediate, some as precursors to perepoxides, open zwitterions or biradicals. The molecules shown in structures 43-51, and relatives thereof, have been... 

Figure 2.9 Chemical quenching of singlet oxygen, (a) The ene reaction — addition of singlet oxygen to an olefin with allylic hydrogen (b) the ene reaction of cholesterol (c) endoperoxide formation by singlet oxygen to imidazole residue as in histidine.

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