Advances in Asymmetric Organotransition Metal-Catalyzed Electrochemistry

Abstract

The recent developments in asymmetric organotransition metal-catalyzed electrochemistry (AOMCE) are summarized. AOMCE processes can be divided into oxidative and reductive variants. In terms of oxidations, asymmetric functionalization of olefins, oxidative kinetic resolution of secondary alcohols or aldehydes, and asymmetric C-H functionalization reactions have been developed. Reductive processes discussed include asymmetric electrochemical carboxylation with carbon dioxide, asymmetric electrochemical decarboxylation, and asymmetric reductive coupling reactions. The combination of chiral ligands, transition-metal catalysts, and electrochemistry provides a novel angle by which to address the longstanding fundamental challenge of stereoinduction in traditional electrochemical organic synthesis.

Recent Applications of Homogeneous Catalysis in Electrochemical Organic Synthesis

“…However, despite substantial growth in electrochemical synthesis, there have been only a few reports of electrochemical asymmetric catalysis. [120][121][122][123][124][125][126] In addition to the usual challenges posed by homogeneous catalysis, asymmetric electrochemical catalysis presents several additional difficulties. In particular, because phosphines can readily undergo single-electron oxidation, the chiral phosphine ligands that have been developed for transition-metal catalysis need extra precautions during reaction design.…”

“…Moreover, Lin et al hypothesized that the multidentate ligand stabilizes the Cu catalyst as cationic intermediates 36-F against cathodic demetallation, and is more susceptible to reductive elimination. In an implementation of asymmetric organo-transition-metal-catalyzed electrochemistry, 125 Mei and co-workers achieved the first example of Cu/TEMPO co-catalyzed electrochemical asymmetric oxidative cross-coupling between cyclic tertiary amines 37-1 and terminal alkynes 37-2 by employing novel chiral bisoxazoline ligand 37-4 under mild conditions (Figure 37a). 146 The protocol exhibits high enantioselectivity and broad functional group tolerance.…”

TEMPO-Enabled Electrochemical Enantioselective Oxidative Coupling of Secondary Acyclic Amines with Ketones

“…In addition, the tunability of the potential and electric current offers a unique handle for organic electrochemistry to precisely tame redox transformations. Therefore, many novel transformations have been developed via the formation of active intermediates using electrochemistry. , Among these reactions, Shono oxidation is a useful approach to establish α-functionalization of amines, which employs various nucleophiles to trapping the in situ formed iminium ion species . However, highly enantioselective Shono-type oxidation reactions are rare and are limited in multiply substituted cyclic amines (Scheme a). ,− To the best of our knowledge, an asymmetric Shono-type oxidation of a secondary acyclic amine has not been achieved.…”

Chiral Organocopper Electrocatalyst-Enabled Oxidative Kinetic Resolution of Primary Alcohols

“…(17)(18)(19) The advancement of asymmetric electrochemical catalytic methods for accessing enantioenriched molecules has garnered broad interest across the organic synthesis community in recent years. (20)(21)(22)(23) Owing to the versatile reactivity of transition metals and the ease of tailoring chiral ligands, the synergistic use of transition metal catalysis and redox mediators is an appealing strategy that could be merged under an umbrella of 'asymmetric electrochemical catalysis'. (24)(25)(26)(27)(28)(29)(30)(31) To achieve such a merger, the redox mediators should efficiently oxidize (or reduce) the substrate into a reactive intermediate that immediately enters an asymmetric catalytic cycle.…”