Novel Template‐Directed Anodic Phenol‐Coupling Reaction

Abstract

Substituted phenols were anodically coupled to the corresponding 2,2'-biphenols via tetraphenoxy borate derivatives. This electrochemical method is particularly useful for methyl-substituted substrates, such as 2,4-dimethyl phenol. The selective ortho-coupling reaction can be easily performed on a multikilogram scale.

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

“…[15] In this electroorganic conversion bis(2,2'biphenoxy)borates are formed as intermediates which turned out to be extraordinarily stable. This prompted us to test them in the supercapacitor cell.…”

“…[17] A direct oxidative coupling to the corresponding fluorinated 2,2'-biphenols by standard methods [18] fails because of the deactivating properties of the fluoro substituents. [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).…”

“…In the course of selective anodic coupling of simple phenols to 2,2'-biphenols, [14,15] we developed a novel borate-templated strategy which allows this reaction to proceed on large scale. [15] In this electroorganic conversion bis(2,2'biphenoxy)borates are formed as intermediates which turned out to be extraordinarily stable.…”

Elektrifizierung der organischen Synthese

“…An elegant approach to guarantee regioselective bond formation and inhibit overoxidation involves templatedirected reactions.W aldvogel and co-workers reported aprotocol for template-directed anodic phenol coupling reactions (Scheme 31). [104] Here,N aB(OAr) 4 was prepared by at woScheme 28. General reaction scheme for the anodic coupling of aryl pyridines by CÀHactivation.…”

“…Template-directed anodic phenol coupling sequence. [104] Scheme 32. The radical cation pool method for CÀH/CÀHcross-couplings of arenes.…”