Comprehensive Comparisons between Directing and Alternating Current Electrolysis in Organic Synthesis

Abstract

Organic electrosynthesis has consistently aroused significant interest within both academic and industrial spheres. Despite the considerable progress achieved in this field, the majority of electrochemical transformations have been conducted through the utilization of direct‐current (DC) electricity. In contrast, the application of alternating current (AC), characterized by its polarity‐alternating nature, remains in its infancy within the sphere of organic synthesis, primarily due to the absence of a comprehensive theoretical framework. This minireview offers an overview of recent advancements in AC‐driven organic transformations and seeks to elucidate the differences between DC and AC electrolytic methodologies by probing into their underlying physical principles. These differences encompass the ability of AC to preclude the deposition of metal catalysts, the precision in modulating oxidation and reduction intensities, and the mitigation of mass transfer processes.

Electrochemical Azidocyanation of Alkenes

“…Organic electrochemistry, renowned for its exceptional controllability via electric current or potential modulation, has emerged as a green synthetic tool of significant interest in recent years [12–25] . Within this field, the transition metal‐catalyzed diazidation of alkenes, capable of accommodating both aryl and alkyl alkenes, has been duly reported [26,27] .…”

“…Organic electrochemistry, renowned for its exceptional controllability via electric current or potential modulation, has emerged as a green synthetic tool of significant interest in recent years. [12][13][14][15][16][17][18][19][20][21][22][23][24][25] Within this field, the transition metalcatalyzed diazidation of alkenes, capable of accommodating both aryl and alkyl alkenes, has been duly reported. [26,27] Whilst these efficacious processes provide a promising foundation for the development of an electrochemical alkene azidocyanation reaction, it is crucial that such a process strategically circumvents the diazidation.…”

“…Remarkably, an assortment of functional groups was accommodated, including ester (5, 6), phthalimide (7), sulfonamide (8), and electrophilic groups such as alkyl bromide (10), alkyl chloride (11), alkyl sulfonates (12, 13), and epoxide (15). Additionally, silyl ether (14), alcohol (16), carboxylic acid (17), ketone (18), silane (19), along with oxidation-labile functionalities such as amine (20), aldehyde (21), and thioether (22), alkynes (23,24), α,β-unsaturated ester (25), were suitable. Furthermore, heterocycles such as benzofuran (26), thiophene (27), and pyrazole (28), and acid-sensitive Boc-protected amines (29, 33) and ketals (30,31) were also accommodated.…”

Electrochemical Azidocyanation of Alkenes

“…Organic electrochemistry, renowned for its exceptional controllability via electric current or potential modulation, has emerged as a green synthetic tool of significant interest in recent years [12–25] . Within this field, the transition metal‐catalyzed diazidation of alkenes, capable of accommodating both aryl and alkyl alkenes, has been duly reported [26,27] .…”

Overview of Recent Scale-Ups in Organic Electrosynthesis (2000–2023)

“…The Baran lab reported a variant of the electrochemical Birch reduction using rapid alternating polarity (rAP) electrolysis, a type of alternating current (AC) electrolysis. , This was demonstrated with heterocycles, including the reduction of methyl thiophene-2-carboxylate ( 82 ) on a 7 g scale to provide alkene 83 in 84% yield (Scheme ). This represented an important step in scaling up rAP electrolysis.…”