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

Abstract

The reductive electrochemical dimerization of ethyl a-bromo-p-halogenophenylacetates, (ABr) (1 )-(3), to the corresponding racemic and meso succinates (AA) (7)-( 9) is reported. Monoesters A H (4)-(6) and epoxides (11)-(13) were also isolated. A n excess of racemic isomer for (7)-( 9) is observed, decreasing in the order of the F, CI, and Br substituent 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(1 1 )-(I 3).The electrochemical reductive dimerization of ethyl a-bromo-phalogenophenylacetates ABr (1)-(3) to give the corresponding succinates AA (7)-( 9) is reported. In principle, symmetrical succinic acids or esters are obtainable, chemically, by Wiirtztype reactions,, by dimerization of thermally or photochemically

High Affinity Central Benzodiazepine Receptor Ligands: Synthesis and Biological Evaluation of a Series of Phenyltriazolobenzotriazindione Derivatives

“…Ethyl phenylacetate 3 , ethyl 4-methylphenylacetate 7 , ethyl 4-methoxyphenylacetate 8 and ethyl 3,4-dimethoxyphenylacetate 10 are commercially available products. The following compounds were prepared in accordance with reported procedures: 2-azidonitrobenzene 1 , 2-azido-4-chloronitrobenzene 2 , ethyl 4-fluorophenylacetate 4 , ethyl 4-chlorophenylacetate 5 , ethyl 4-bromophenylacetate 6 , ethyl 2-fluorophenylacetate 9 …”

“…Ionic 1,3-dipolar cycloaddition of the appropriate azide 1 and 2 , , to ethyl phenylacetates 3 - 10 , , furnished the 1-(2-nitrophenyl)-4-aryl-5-oxo[1,2,3]triazoles 11 − 23 .…”