Cations intrazeolite photooxygenation

The effect of cations on ene regiochemistry of several intrazeolite photooxygenations have been examined83 (Fig. 20). The effect is modest but the unique... 

Fig. 28 A. Intrazeolite photooxygenation of a -chlorosulfide that requires a hydroperoxy sulfonium ylide and B. The formation of an extended cation complexed persulfoxide that can potentially inhibit hydroperoxy sulfonium ylide formation.

Type 1 intrazeolite photooxygenation of alkenes has been also reported to give mainly allylic hydroperoxides (Scheme 42). In this process, the charge transfer band of the alkene—O2 complex within Na-Y was irradiated to form the alkene radical cation and superoxide ion. The radical ion pair in turn gives the allylic hydroperoxides via an allylic radical intermediate. On the other hand, for the Type II pathway, singlet molecular oxygen ( O2) is produced by energy transfer from the triplet excited state of a photosensitizer to 02. 

TABLE 18. Cation-dependent regiochemical control in the intrazeolite photooxygenation of 1- phenyl-3-methyl-2-butene... 

SCHEME 45. Cation-directing twin regioselectivity in the intrazeolite photooxygenation of trisub-stituted alkenes... 

Stratakis, M., Raptis, C., Sofikiti, N., Tsangarakis, C., Kosmas, G., Zaravinos, I.-P., Kalaitzakis, D., Stavroulakis, D., Baskakis, C. and Stathoulopoulou, A. (2006) Intrazeolite photooxygenation of chiral alkenes. Control of facial selectivity by confinement and cation-Tt interactions. Tetrahedron, 62 (46), 10623-10632. 

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