Lactone-derived carbon-centered radicals: formation and reactivity with oxygen.
[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.
Bejan
E V
EV
Department of Chemistry, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5.
Font-Sanchis
E
E
Scaiano
J C
JC