Free radical chain reactions of ate complexes. Electron transfer processes 42

Iodide ion promotes the free radical reaction of isopropylmercury idide with bromotrichloromethane to yield isopropyl bromide with rate enhancement in the order of 104. The reaction involves electron transfer from i‐PrHgI2− to the trichloromethyl radical in a long kinetic chain process. Iodide ion also promotes the free radical chain conjugate addition of tert‐butylmercury chloride to α,β‐unsaturated ketones, esters, phosphonate esters and sulfones. Competitive reactivity studies indicate that lithium di‐tert‐butylcuprates or tri‐tert‐butylzincates react with 2‐cycloalkenones by a mechanism involving attack by tert‐butyl radicals. No evidence for radical attack is observed for the corresponding n‐butyl ate complexes of copper or zinc.