Organic Letters · 2001 · 80 citations · 17 references
Natural SciencesChemistryMedicinal ChemistryOrganic ChemistryRedox BiochemistrySynthetic Medicinal ChemistryMolecular Orbital TheoryOxidation ReactionsOxygen EffectRadical ReactionsReactive Oxygen SpeciesDelocalization TheoryElectron Correlation EffectsElectron DelocalizationElectron-withdrawing GroupsHydrogen Abstraction ReactionsLigand Steric EffectsRadical Stability
[reaction: see text] Several lactones were examined to test the reactivity of carbon-centered radicals toward oxygen. Notably, the radical derived from 2-coumaranone (4) is unreactive toward oxygen, while 2-cuomaranone itself shows enhanced reactivity toward hydrogen abstraction by alkoxyl radicals. We propose that five parameters influence diminished reactivity toward oxygen, i.e., (a) benzylic resonance stabilization, (b) unpaired spin delocalization on oxygen, (c) favorable stereoelectronic effects, (d) electron-withdrawing effects, and (e) steric effects.
17