Triplet oxygen peroxidation

The electrolysis of adamantylideneadamantane solutions affords the radical cation, which can add molecular (triplet) oxygen to give the peroxide radical anion, which can react with adamantylideneadamantane to give the 1,4-diradical and another molecule of adamantylideneadamantane radical cation. The latter reacts with oxygen, to continue the chain of the reaction, while the former cyclizes to the corresponding 1,2-dioxetane (Scheme 18) (81JA2098). 

The reactions outlined in Schemes 8-11 indicate that 1,4-diradicals can trap triplet oxygen to give 6-membered cyclic peroxides in variable yields. For example, even under 10 atm oxygen pressure, Ph2CO-sensitized photolyses of the azoalkanes 42 afford the dienes 43 and bicydo[2.1.1]hexanes 44 as the major products while the bicyclic peroxides 45 are formed in very poor yields 1.5%) (Scheme Failure in oxygen... 

A number of semibullvalenes and some barbaralanes, which undergo a facile Cope rearrangement via bicyclooctadienyl diradicals, produce various cyclic peroxides on exposure to triplet oxygen ". Thus, cyclopentano semibullvalene 82a is peroxidated with air to give a mixture of 5-membered 83a and 6-membered endoperoxide 84a in a 1 2 ratio, whereas the cyclohexano derivative 82b yields only the 6-membered cyclic peroxide 84b (Scheme 15). The energy in the highly strained mono(Dewar benzene) isomer of... 

Thiophene, dioxirane oxidation, 1156 Thiourea, dialkyl peroxide synthesis, 706 1,4-Thioxane, oxidation, 805-6 Thiyl radicals, triplet oxygen domino reactions, 221-3, 224, 225, 226 THPO (1,2,3,4-tetrahydronaphthyl hydroperoxide), 331-2 Thromboxanes, from arachidonic hydroperoxides, 612... 

Special interest has been devoted to the reaction of oxygen on carbanionic sites.- It has been established that triplet oxygen acts as an electron acceptor, and that the reaction may yield either terminal hydroperoxy or alcohol functions. Depending on the reaction conditions, the latter group which originates from a disproportionation process between a hydro-peroxidate and a carbanlon may be observed. By choosing proper conditions one can get polymers terminated quantitatively with hydroperoxide groups. The latter can be used in a later step as a radical initiator to prepare new block copolymers. 

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