Advances on the Merger of Electrochemistry and Transition Metal Catalysis for Organic Synthesis

Abstract

Synthetic organic electrosynthesis has grown in the past few decades by achieving many valuable transformations for synthetic chemists. Although electrocatalysis has been popular for improving selectivity and efficiency in a wide variety of energy-related applications, in the last two decades, there has been much interest in electrocatalysis to develop conceptually novel transformations, selective functionalization, and sustainable reactions. This review discusses recent advances in the combination of electrochemistry and homogeneous transition-metal catalysis for organic synthesis. The enabling transformations, synthetic applications, and mechanistic studies are presented alongside advantages as well as future directions to address the challenges of metal-catalyzed electrosynthesis.

Figure 1.

Direct (A) and indirect (mediated) (B) electrosynthesis in the context of anodic oxidation reactions.

Figure 2.

Pd (A) or Ni (B) catalyzed (nonelectrochemical and electrochemical) amination of aryl halides for the synthesis of aryl amines.

Figure 3.

Cell notations used in this review. The following notations are used to easily differentiate the electrochemical conditions used (constant current vs constant potential electrolysis, the use of a divided vs undivided cell, and anodic oxidation vs cathodic reduction) in a given reaction scheme. A, constant current electrolysis; V, constant potential electrolysis; (+)X, anode material, (−)Y, cathode material.

Figure 4.

(A) Electrocatalytic protodehalogenation and dimerization of organohalides, and (B,C) generation of arylzinc reagents.

Figure 5.

Electrocatalytic addition of organohalides to (activated) alkenes and alkynes. Cyclic voltammograms in (D) is reproduced from ref . Copyright 2006 American Chemical Society.

Figure 6.

Electrocatalytic addition of organohalides to carbonyls and imines.

Figure 7.

(A) General scheme and proposed mechanism for the metal-catalyzed carboxylation of organohalides with CO₂. (B–D) Examples of electrocatalytic carboxylation of organohalides to generate carboxylic acids.

Figure 8.

(A) Cross-electrophile coupling reaction of two organo(pseudo)halides and comparison of selectivity control and reduction approach using electrochemical and nonelectrochemical approaches. (B–D) Nickel and cobalt catalyzed electrochemical cross-electrophile couplings. Cyclic voltammograms in (B) are reproduced from ref . Copyright 2013 American Chemical Society.

Figure 9.

Enantioselective electrocatalytic cross-electrophile couplings of organohalides.

Figure 10.

Nickel catalyzed electrochemical cross-electrophile coupling of aryl and alkyl halides. (B,C) Use of shuttle molecules for overcharge protection in nickel catalyzed electrochemical cross-electrophile sp²–sp³ couplings. (A) Reproduced from ref . Copyright 2020 American Chemical Society.

Figure 11.

(A) General metal-catalyzed Heck reactions and proposed mechanism. (B–D) Pd and Ni catalyzed electrochemical Heck and Suzuki cross-coupling reactions. Figures in (C) are reproduced from ref . Copyright 2010 American Chemical Society.

Figure 12.

Electrocatalytic cross-coupling reactions of aryl halides to generate carbon–heteroatom bonds.

Figure 13.

Electrocatalytic annulation reactions of alkenes and allenes and Wacker oxidations of alkenes.

Figure 14.

Electrocatalytic difunctionalization and heterodifunctionalization of alkenes.

Figure 15.

Electrocatalytic carboxylation and carbonylation reactions of alkynes.

Figure 16.

Electrocatalytic annulations of alkynes.

Figure 17.

Electrocatalytic cycloaddition reactions of alkynes with azides and α-nitroketones.

Figure 18.

Palladium electrocatalytic Fujiwara–Moritani transformation.

Figure 19.

Palladium electrocatalytic C–H functionalization of phenylpyridines and benzamides.

Figure 20.

Palladium electrocatalytic C–H functionalization of oximes, quinolines, and other directing groups.

Figure 21.

Enantioselective electrocatalytic palladium C–H functionalization by a transient directing group.

Figure 22.

Electrocatalytic rhodium cross-dehydrogenative alkenylation and alkenylation reaction.

Figure 23.

Electrochemical Rh catalyzed C–H annulations.

Figure 24.

Electrocatalytic rhodium C–H phosphorylation.

Figure 25.

Electrochemical ruthenium catalyzed annulation arene C–H annulation with alkynes.

Figure 26.

Electrochemical ruthenium catalyzed arene C–H oxidation aryl amides and ketones.

Figure 27.

Electrochemical cobalt catalyzed arene C–H oxygenation and annulation.

Figure 28.

Electrochemical cobalt catalyzed arene C–H functionalization.

Figure 29.

Copper/TEMPO electrocatalyzed oxidation of alcohols.

Figure 30.

Electrocatalytic functionalization and cross-coupling of organoboron reagents.