Shahabuddin Siddiqui

Reactions following electron transfer: Origins of selectivity in the reaction of radicals with carbanions☆

Abstract 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-alklation of nitrocarbanions and for the absence of O-arylation in the SRN1 arylation of enolates. The lack of reactivity of other carbanions is rationalized on thermodynamic grounds.