Electrochemistry of the Carbon–Halogen Bond

Abstract

Introduction General Reaction Types Cathodic Reactions Anodic Reactions Acknowledgements

Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis

“…The following methods for substrate activation primarily involve cathodic reduction as oxidative methods are still underdeveloped but a few exceptions exist. , A classic electrochemical method of synthesizing cyclopropanes is cathodic reduction of either 1,3-dibromoalkanes or 1,3-di­(methanesulfonate)­alkanes to yield 1,3-difunctionalized alkanes. Electrolysis has proven useful for the reduction of alkyl halides and the formation of organometallic reagents in situ . − While the use of Zn dust to reduce 1,3-dibromopropane to afford cyclopropane in 56% yield was reported in 1882, its electrochemical analog was reported 85 years later by Rifi in 1967 . The method involves potentiostatic ( E c = −2.0 ± 0.1 V vs SCE), two-electron reduction of 3-bromopropyltriethylammonium bromide, which forms a highly reactive carbanion that undergoes intramolecular substitution at the alkylammonium to eject triethylamine and form cyclopropane (yield not reported).…”