Oxygenation, photo

It was of interest then to prepare several alkoxybutenolides (XVI) for testing. Some can be prepared by photo-oxygenation as stated... 

Isoe, S., S. B. Hyeon, S. Katsumura et al. 1972. Photo-oxygenation of carotenoids. II. The absolute configuration of ioliolide and dihydroactinidioline. Tetrahed. Lett. 13 2517-2519. 

Clennan, E.L. (2005). Photo-oxygenation of the ene-type. In Synthetic Organic Photochemistry, pp. 365-390. Marcel Dekker, New York... 

Schaap, A.P., Siddiqui, S., Prasad, G., Palomino, E. and Sandison, M. (1985). The photochemical preparation of ozonides by electron-transfer photo-oxygenation of epoxides. Tetrahedron 41, 2229-2235... 

Matsubara, C. and Kojima, M. (2001). Photo-oxygenation and photodimerization of 4-methoxystyrene in NaY. The role of co-adsorbed water and ankene-oxygen charge-transfer complex. Res. Chem. Int. 27, 975-989... 

Calzaferri, G., S. Hug, T. Hugentobler, and B. Sulzberger (1984), "Self-Sensitization of Photo-Oxygen Evolution in Ag+ Zeolites Computer-Controlled Experiments," J. Photochem. 26, 109-118. 

It is important to differentiate between the effects of a nonnucleophilic salt such as Mg(C104)2 on one hand, and a weak nucleophilic salt such as Et4NOAc on the other. The effect of nonnucleophilic salts on photo-oxygenation via electron transfer can be understood as the stabilization of ion-radicals by coulombic interaction, resulting in the suppression of a back electron transfer between ion-radicals. The weak nucleophilic salts cause unusual effects. The addition of the anionic nucleophile to the cation-radical and complexation of the weak nucleophilic salt with the ion-radicals bring about these effects. 

CONTROL OF PHOTOCATALYTIC REACTIVITY IN PHOTO-OXYGENATION REACTION... 

Scheme 10 Selective photo-oxygenation of -xylene catalyzed by AcrR via photoin-duced electron transfer. (From Ref. 109.)...

The synthesis of the non-natural ( )-7,14-epz-l(15),8-dolastadien-7,14-ol (rac-7yl4-epi-l09) was published by Paquette in 1986 and is highlighted by a photochemical rearrangement of the 6,6,6-tricyclic a,yS-epoxy ketone 148 into the 5,7,6-tricyclic dolastane skeleton (149) (Scheme 23) [84]. The succeeding hydroxylation of carbon atom by photo oxygenation with singlet oxygen as well as a DIBAH reduction of a keto function proceeded with an undesired substrate-induced diastereoselectivity to provide the racemic 7,14-epimer of the natural dolastane 109. 

OXYGEN, OXIDES 0X0 ANIONS Oxygen, photo-induced incorporation, PHOTO-OXYGENATION OXYGEN RADICALS Oxygen transport in erythrocytes,... 

C3 Aryl ttioxanes (75a, 75b) 5 steps (R) Dye-sensitized photo- oxygenation 30 nM (NF54) 10 mgkg i Toxicity studies reved that 11b has a similar tiierapeutic index to artelinic acid 109, no... 

In contrast to earlier literature reports, photo-oxygenation of 17/3-hydroxyoestr-5(10)-en-3-one has been shown not to be stereospecific, since a mixture of 10a- and 10/3-hydroperoxy-3-oxo-A -compounds was obtained. Thermal rearrangement of these products gave the 10a- and 10/3-hydroxy-3-oxo-A -compounds. Photo-oxygenation of 5a-cholesta-1,3-diene led only to cholesta-1,4-... 

Two syntheses have been reported for 14j8-hydroxyandrostan-17-ones which are useful intermediates in cardenolide synthesis. Photo-oxygenation of 5a-androsta-14,16-diene gave the epidioxide (296) which was transformed with base into... 

The tricyclic pyrano-l,2,4-trioxanes 264a and 264b were likewise achieved from the photo-oxygenation of 2-oxabicyclo[4.6.0]dodec-l(6)-ene 263, as an epimeric mixture (Scheme 45) <1997H(46)451>. 

The photo-oxygenation of phosphorus ylides with singlet oxygen is a simple reaction. A typical example is methoxycarbonylbenzylidenetriphenylphosphorane (58), which yields methylphenylglyoxylate (59) quantitatively after irradiation (equation 21)100. 

If protoporphyrin-IX is handled in air and light, polar green compounds are produced due to photo-oxygenation this type of transformation to produce photo-protoporphyrin-IX... 

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