Photooxygenation of olefins

Phosphoryl-stabilized anions, 25, 2 Photochemical cycloadditions, 44, 2 Photocyclization of stilbenes, 30, 1 Photooxygenation of olefins, 20, 2 Photosensitizers, 20, 2 Pictet-Spengler reaction, 6, 3 Pig liver esterase, 37, 1 Polonovski reaction, 39, 2... 

Efficient Photooxygenation of Olefins by a C60 Derivative Bearing an Organofluorine Tail Nagashima, H. Hosoda, K. Abe, T. Iwamatsu, S. Sonoda, T. Chem. Lett. 1999, 469-470. 

Formation of cyclic peroxides by photooxygenation of olefins 93CSR59. 

The most important photocatalytical reactions are oxidation reactions which include the oxygenation of unsaturated systems, but also oxidations of saturated carbons with or without incorporation of oxygen (C-H activation). The photooxygenation of olefins in the presence of Ti or Mo catalysts leads one-pot to epoxy alcohols (17) via singlet oxygen (eq. (9)) [82]. 

Reviews have appeared of the solid-state dimerisation of thiones, the photooxidation of sulphur compounds, thiocarbonyl photochemistry, the DCA sensitized photooxygenation of olefins, and of the role of intersystero crossing steps in singlet oxygen chemistry. ... 

Denny, R. W., and A. Nickon Sensitized Photooxygenation of Olefins. Org. Reactions... 

Scheme 17.10 Reaction pathways suggested by Tokumaru et al for photooxygenation of olefins to afford epoxides and/or carbonyls.

Tokuyama, H. and Nakamura, E., Synthetic chemistry with fullerenes. Photooxygenation of olefins, /. Org. Chem., 54,1135,1994. 

In the photooxygenation of electron-rich olefins with allylic hydrogen atoms, ene reactivity usually dominates [96]. Nevertheless, other reactions become the preferred reaction mode. Inagaki et al. [92] attributed the exclusive [2h-2] cycloaddition... 

The argument of the directing effect of lone pairs on the substiment [92] easily extends to the alkyl cases. The orbital interaction (Scheme 20) [103] in the pere-poxide quasi-intermediate suggests the stabilization occurs by the simultaneous interaction of O with two allylic hydrogens on the same side of the alkene. Photooxygenation of trisubstituted olefins revealed a strong preference for H-abstraction from disubstituted side of the double bond [104, 105],... 

Wittig reaction of 10 with pentyl phosphonium salt in the presence of NaH gave Z-olefin 11 selectively. Dye-sensitized photooxygenation of 11 proceeded exclusively to give the endoperoxides 12a and 12b in almost quantitative yield as a roughly 1 1 mixture of two diastereomers. 

SCHEME 37. Threo/erythro diastereoselectivity in the photooxygenation of chiral olefins without heteroatoms at the stereogenic centre... 

The oxazolidinone-substituted olefin Ic (Scheme 3) constitutes another fortunate substrate for the diastereoselective synthesis of a chiral dioxetane , which is of preparative value for the enantiomeric synthesis of 1,2 diols . For example, the photooxygenation of the enecarbamate Ic produces the asymmetric dioxetane 2c in >95% jt-facial diastereoselectivity. The attack of the O2 occurs from the jt face anti to the isopropyl... 

The main types of substrates investigated so far are polycyclic aromatic compounds, aryl substituted carbo- and heterocyclic pentadienes, cyclic 1,3-dienes, furans, and olefins. It has turned out that type II photooxygenation of these compounds in solution occurs via the oxygen-activation mechanism. 

On this ground, DCA was found a suitable sensitizer to induce the photooxygenation of a great variety of organic compounds such as alkenes [84,94-98], alkynes [99,100], sulfides [84,98,101], dienes [84], sulfoxides [102], cycloalkanes [103,104], cycloalkenes [105,106], epoxides [107,108], aziridines [109], allenes [110], dioxenes [111], p-dioxins [111,112], aromatic substrates [113], tertiary amines [114], and of great interest from the mechanistic point of view, sterically hindered olefines [97,115-117]. 

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