Electrochemical synthesis of diethyl 2,3-bis-p-halogenophenylsuccinates; reduction of α-bromo-p-halogenophenylacetates1

Abstract

The reductive electrochemical dimerization of ethyl α-bromo-p-halogenophenylacetates, (ABr)(1)–(3), to the corresponding racemic and meso succinates (AA)(7)–(9) is reported. Monoesters AH (4)–(6) and epoxides (11)–(13) were also isolated. An excess of racemic isomer for (7)–(9) is observed, decreasing in the order of the F, Cl, and Br substiuent in the phenyl group. Voltammetric experiments show only slight differences between the reduction potentials of the isomeric meso and racemic compounds (8), whereas in the case of the isomeric p-bromo-substituted compounds (9) the reduction potentials are almost identical. The meso compounds can be distinguished from the DL isomers by n.m.r. spectroscopy. This feature is also observed in the n.m.r. spectra of epoxides (11)–(13).