Direct and indirect reduction of ethyl β-bromopropionate and ethyl γ-bromovalerate in DMF solutions

Abstract

The electrochemical reduction of CH 2(Br)CH 2COOEt(I) and CH 3CH(Br)CH 2CH 2COOEt(II) in dimethylformamide solutions containing Et 4NclO 4 as supporting electrolyte was studied by means of polarography, cyclic voltammetry and coulometry at mercury, gold and vitreous carbon electrodes. CH 3CH 2COOEt(III), CH 2=CHCOOEt(IV) and (CH 2CH 2COOEt) 2(V) were obtained from the electroreduction of (I) at an Hg pool, and CH 3(CH 2) 3 COOEt(VI), CH 3-CH=CHCH 2COOEt(VII) and (CH 3−CH−CH 2CH 2COOEt) 2(VIII) were formed from (II) under the same conditions. The percentage ratio among the various products depends on the potential, the proton donor presence and the nature of the ester treated (I or II). The feasibility of the indirect reduction of (I) and (II) by means of anion radicals of aromatic hydrocarbons was studied; evidence for a different behaviour of (I) and (II) was obtained.