Mechanism of the Reaction of ¹δ_g Excited Oxygen with Olefins. II. Elimination of the Concerted "Ene" Mechanism as the Route to Allylic Hydroperoxides

Abstract

it is obvious that there is no clear evidence for the presence of any significant diamagnetic ring current.(14) We have not yet excluded the possibility that a second double bond isomer of 1 in addition to 5 was produced and isomerized to an as yet uncharacterized CsHsO compound. The structural assignment of 5 is solely on the basis of the selection rule.(15) S. Masamune and N. T. Castellucci, Angew. Chem. Intern. Ed. Engl, 3, 582 (1964).

Mechanism of addition of singlet oxygen to olefins and other substrates

“…The preliminary results with a limited number ofsubstituents are that the product distribution is not far from 1:1 secondary unconjugated (14) to conjugated (15) hydroperoxide, and that this ratio is invariant with substituent. The rates vary only slightly, and are roughly in the inductive order, with p-methoxy being slightly slower than p-methyl.…”

Substituent Effects in Dye-sensitized Photooxidation Reactions of Furans

“…However, even with this small substituent effect one might have expected the product ratio to vary with the substituent. In addition to a concerted mechanism, the substituent effect could b"e explained either by the formation of a partial charge-transfer complex as an initial ' (8). Substituent effects on subsequent reactions which would affect product ratios would be difficult to predict.…”

The Isomeric Compositions of Hydroperoxides Produced by Oxidation of Arachidonic Acid with Singlet Oxygen

“…28 ) The eight regioisomers of MHP, that is 5-, 8-, 9-, 11-, 12-and 15-isomer (conjugated diene isomer), and 6-and 14-isomer (nonconjugated diene isomer), are formed from arachidonic acid as the result of the binding of 1 0 2 to the double bonds at LIS, 8, 11, 14 position. 23 ) The difference in the isomeric compositions of MHP between autocatalytic oxidation and 1 0 2 oxidation was previously reported for methyl oleate, methyl linoleate and methyl linolenate.13) Autocatalytic oxidation of arachidonic acid yields six regioisomeric MHP, that is, 8-, 9-, 11-and 12-isomer whose hydroperoxy group is located on the inside of the tetraene structure (inner isomer), and 5-and 15-isomer, on the outside of the tetraene structure (outer isomer).…”