Electrocatalysis as an enabling technology for organic synthesis

Abstract

Electrochemistry has recently gained increased attention as a versatile strategy for achieving challenging transformations at the forefront of synthetic organic chemistry.

Electrochemical oxidative N–H/P–H cross-coupling with H2 evolution towards the synthesis of tertiary phosphines

“…As an attractive alternative to traditional chemical oxidants, electrosynthesis achieves the function of chemical oxidants by using an anode, 8 and thus can not only realize oxidative cross-coupling reactions under exogenous-oxidation-free conditions, 9 but also provide a new opportunity for oxidative cross-coupling reactions that cannot occur with traditional chemical oxidants. Over the past five years, R 1 –H/R 2 –H cross-coupling reactions via electrochemical oxidation have been extensively researched.…”

Kinetics‐Based Approach to Developing Electrocatalytic Variants of Slow Oxidations: Application to Hydride Abstraction‐Initiated Cyclization Reactions

“…In situ electrochemical oxidant regeneration provides an attractive option [1] for mitigating the environmental and economic consequences of oxidation reactions. [2] Stahl's report of alcohol oxidation reactions that employ low nitroxyl loadings to generate oxoammonium ions through anodic oxidation [3,4] provides an excellent illustration of the promise in this approach. Oxoammonium ions are also excellent hydride abstracting agents that can be used in bond-forming reactions, though electrocatalytic variants of these processes are not widely utilized.…”

“…In situ electrochemical oxidant regeneration provides an attractive option [1] for mitigating the environmental and economic consequences of oxidation reactions [2] . Stahl's report of alcohol oxidation reactions that employ low nitroxyl loadings to generate oxoammonium ions through anodic oxidation [3,4] provides an excellent illustration of the promise in this approach.…”

Electrocatalytic Allylic C−H Alkylation Enabled by a Dual‐Function Cobalt Catalyst**

“…Cobalt represents an attractive alternative to noble metals for transition metal catalysis due to its greater natural abundance and cost efficiency. [13][14][15][16][17][18][19][20][21][22][23][24] In view of the challenges associated with the selective functionalization of allylic CÀ H bonds of unactivated alkenes through organometallic activation, we envision a radical-based electrocatalytic approach [25][26][27][28][29][30][31][32][33][34][35][36][37] to expand the scope of allylic CÀ H alkylation and eliminate the need for external chemical oxidants (Scheme 1b). [38] Building on our previous studies on intramolecular allylic CÀ H functionalizations, [39] we surmise that the acidic carbon nucleophile can be oxidized electrocatalytically with a cobalt-based molecular catalyst to generate an electron-deficient carbon-centered radical, [39][40][41] which then adds to the alkene to afford an alkyl radical.…”

“…This preference for the cleavage of the 3°γ-CÀ H bond over the 2°CÀ H at the α-position was likely caused by the relatively low bond dissociation enthalpy (BDE) of the former. 1,1-Disubstituted alkenes also reacted exclusively via the cleavage of the γ-CÀ H bonds (25)(26)(27)(28)(29). In the cases of 27-29, all of which contained two different types γ-CÀ H bonds, the reactions occurred exclusively at the more accessible Me group to give the contra-thermodynamic terminal alkenes instead of the more stable internal alkenes that would derive from reaction at the weaker 2°or 3°CÀ H bonds adjacent to the nitrogen substituents.…”