REACTIONS FOLLOWING ELECTRON TRANSFER ORIGINS OF SELECTIVITY IN THE REACTION OF RADICALS WITH CARBANIONS

Article abstract of DOI:10.1016/0040-4020(82)80125-7

The regiochemistry observed upon arylation of ambident carbanions by phenyl radicals can be readily explained by consideration of the site of greatest basicity.Thus 1,3-diphenylindenyl anion is arylated to give predominantly 1,1,3-triphenylindene despite the presumed greater stability of the intermediate leading to 1,2,3-triphenyl indene, that is, the 1,2,3-triphenylisoindene radical anion.This explanation may also account for the preference of C-alkylation rather than O-alkylation of nitrocarbanions and for the absence of O-arylation in the S_RN1 arylation of enolates.The lack of reactivity of other carbanions is rationalized on thermodynamic grounds.