Schenck reaction

Ab initio calculations of the transition structures for the Schenck reaction of singlet oxygen suggest that Me substitution makes the transition structure earlier and more stable and that the transition-state geometry is sensitive to the position of Me substituents. ... 

B. Olefins as Substrates of Photosensitized Oxygenation Reactions— The Schenck Reaction... 

According to the reaction scheme of the Schenck reaction one should expect four more products in the case of (+)-carvomenthene (19) and at least four more products in the case of (+)-limonene (16). The fact that with limonene no products were obtained which originate from an oxygen attack on the A8 double bond, is in agreement with the general rule that type II photosensitized oxygenation reactions occur much faster with tri- and tetrasubstituted ethylenes than with di- or monosubstituted ones (see p. 71). 

C>2 is known to react with olefins to form allylic hydroperoxides via the Schenck reaction. Even if cyclohexene has a rather low reactivity towards 02 [19], it is likely that at least part of the allylic oxidation products (enylOOH, enol, enone) arise from a 02 reaction, rather than from a free radical chain process. 

Scheme 24 Erythro and threo selectivity in the Schenck reaction.

Scheme 26 Preparation of a natural product using the Schenck reaction.

Quasi, H., Dietz, T, and Witzel, A., Tetra(2,6-dichlorophenyl)porphyrin a superior sensitizer for the singlet-oxygen ene reaction (Schenck reaction), Liebigs Ann., 1495,1995. 

Brilnker, H.-G. and Adam, W., Diastereoselective and regioselective singlet oxygen ene oxyfunc-tionalization (Schenck reaction) photooxygenation of allylic amines and their acyl derivatives,/. Am. Chem. Soc., 117, 3976,1995. 

Adam, W. and Klug, R, P-Stannyl allylic alcohols through photooxygenation (Schenck reaction) of vinylstannanes and reduction of the resulting aUyhc hydroperoxides synthesis and selected transformations,/. Org. Chem., 59, 2695, 1994. 

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