Radical coupling with oxygen

The resulting glycyl radical couples with the oxygen radical that is bound to CuB (step e). 

Scheme 13 Oxygenation of methyl viologen cation radical via radical-radical coupling with O2...

Moeller synthesized tetrahydrofuran natural products (+)-linalool oxide <01OL2685> and (+)-nemorensic acid <01TL7163> by employing intramolecular coupling reactions of enol ether radical cations as well as ketene dithioacetal radical cations with oxygen nucleophiles. 

A carbon radical couples with molecular oxygen... 

Such solvent-derived radicals can induce the decomposition of the hydroperoxide or react with oxygen in the system to form peroxidic solvent molecules. They may also react with other radicals either by coupling or disproportionation. 

Various side reactions may complicate RAFT polymerization. Transfer to solvents, monomer and initiator occur as in conventional radical polymerization. Other potential side reactions involve the intermediate radicals 165 and 167. These radicals may couple with another radical (Q ) to form 271 or disproportionate with Q to form 270. They may also react with oxygen. The intermediate radicals 165 and 167 are not known to add monomer. 

GUO c, CAO G, SOFIC E and PRIOR R L (1997) High-performance liquid Chromatography coupled with coulometric array detection of electroactive components in fruits and vegetables Relationship to oxygen radical absorbance capacity, J Agric Food Chem, 45, 1787-96. 

The spin density of tocopheroxyl radical 2, a classical phenoxyl radical, is mainly concentrated at oxygen 0-6, which is the major position for coupling with other C-centered radicals, leading to chromanyl ethers 5. These products are found in the typical lipid peroxidation scenarios. Also at ortho- and para-positions of the aromatic ring, the spin density is increased. At these carbon atoms, coupling with other radicals, especially O-centered ones, proceeds. Mainly the para-position (C-8a) is involved (Fig. 6.3), leading to differently 8a-substituted chromanones 6. 

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