| Popis: |
While diethyl malonate with diphenyliodonium chloride in t-butyl alcohol containing potassium t-butoxide gave only low yields of diethyl phenylmalonate and diethyl diphenylmalonate, reaction with 4,4′-dichlorodiphenyliodonium chloride gave good yields of the corresponding mono- and di-(4-chlorophenyl) derivatives. In methanol, ethanol and 2-propanol arylation was repressed, the main reactions now involving oxidation-reduction: dehydrogenation of the solvent and reduction of the diphenyliodonium ion. Such reactions gave ethylidene-bis-malonic ester in good yield. These observations are discussed in terms of a reaction mechanism of which the first step is electron transfer within an iodonium ion-carbanion pair (Ar2I+R−) to form a radical pair (Ar2I·R· or Ar·R·), whose fate depends in part on the solvent. |
