ortho‐Selective Phenol‐Coupling Reaction by Anodic Treatment on Boron‐Doped Diamond Electrode Using Fluorinated Alcohols

Abstract

Enlarged scope by fluorinated mediators: Oxyl radicals are easily formed on boron-doped diamond (BDD) electrodes and can be exploited for the ortho-selective coupling to the corresponding biphenols (see scheme). At partial conversion, a clean transformation is achieved that can be applied to electron-rich as well as fluorinated phenols.

Contributions of organic electrosynthesis to green chemistry

“…Passivation and unwanted side products could be decreased that way, because due to the high oxygen overpotential of the BDD anode deposits and electroactive side products are degraded slightly faster than the product. Thereby the phenols 6-12 could be coupled in good to moderate yields (Scheme 4) [18]. In addition phenol 11 can be coupled in 29% yield in acetonitrile/LiClO 4 at a glassy carbon anode [19].…”

Anodische Phenol‐Aren‐Kreuzkupplung an bordotierten Diamantelektroden

“…[15,22] Trotz der Abspaltung eines Protons nach dem Oxidationsschritt stellt die Phenoxylspezies immer noch ein Elektrophil dar. [23] Ein elektro- [19] Da HFIP jedoch bei den Oxidationspotentialen der Substrate an BDD elektrochemisch stabil war (siehe die Hintergrundinformationen), kann die bisher angenommene Wirkungsweise als Redoxvermittler definitiv ausgeschlossen werden. [19] Das nichtnucleophile und protische Additiv HFIP erhöht die Stabilität von radikalischen Zwischenstufen um mehrere Größenordnungen.…”

Bis(2,2′‐biphenoxy)borates for Electrochemical Double‐Layer Capacitor Electrolytes

“…[15,19] Only when boron-doped diamond anodes are employed, less fluorinated 2,2'-biphenols can be obtained in moderate yields. [20] However, we developed a reliable and general sequence to prepare the highly fluorinated 2,2'-biphenols 3 (Scheme 1). [21,22] The synthesis starts with fluorinated phenols which are converted into the iodo anisoles 2 by a telescoped iodination/methylation sequence.…”