ELECTRON-TRANSFER-INDUCED REDUCTIVE CLEAVAGE OF PHTHALANS - REACTIVITY AND SYNTHETIC APPLICATIONS

The behavior of phthalan (1a) was investigated under conditions of ele ctron transfer from alkali metals in aprotic solvents. Reaction with l ithium in the presence of a catalytic amount of naphthalene in THF led to the reductive cleavage of an arylmethyl carbon-oxygen bond, with f ormation of a stable dilithium compound. Trapping of this intermediate with several electrophiles (alkyl halides, carbonyl derivatives, CO2) was successful. The extension of this procedure to several substitute d phthalans (1b-i) was investigated, and the regiochemistry as well as the synthetic usefulness of these reactions are discussed.