Electrochemical synthesis of copper(i) acetylides via simultaneous copper ion and catalytic base electrogeneration for use in click chemistry

Abstract

We report an efficient and sustainable electrochemical synthesis of copper(i) acetylides using simultaneous copper oxidation and Hofmann elimination of quaternary ammonium salts.

Synthetic Access to 1,3-Butadiynes via Electro-redox Cuprous-Catalyzed Dehydrogenative Csp–Csp Homocoupling of Terminal Acetylenes

“…43 Besides, the catalytic and energy efficiency of our electroredox process is higher compared to the relevant electrochemical Glaser-Hay coupling approaches. [26][27][28]44 All compounds were characterized by standard spectroscopic techniques. As an illustrative example, compound 2a exhibited two characteristic peaks at 74.1 and 81.7 ppm in its 13 C NMR spectrum, which agrees with the two acetylenic carbons.…”

Alkynes as Building Blocks, Intermediates and Products in the Electrochemical Procedures Since 2000

“…The same group improved the above‐described electrochemical procedure using tetrabutylammonium (TBA) electrolyte salt to produce Bu 3 N. The reduction of TBA occurs by a single‐electron transfer/Hofmann‐type elimination able to generate tertiary amine bases and to avoid the use of other bases such as DABCO [27] …”

Electrifying green synthesis: recent advances in electrochemical annulation reactions

“…191 Recently, Wilden and co-workers proposed an electrochemical synthesis of copper(I) acetylides 175 (Scheme 46) using simultaneous oxidation of copper foil and Hofmann elimination of quaternary ammonium salts. 192,193 The authors evaluated its importance through a click reaction (CuAAC reaction), successfully obtaining two conditions in a one-pot electrochemical process, which is a promising approach for these reactions. According to control reactions, they propose that the active Cu species is Cu(MeCN) 4 X (X = PF 6 or CH 3 C 6 H 4 SO 3 ).…”