The chemists’ pursuit of the ideal synthesis and functionalization of indole derivatives has lasted over 150 years as their scaffolds have been widely found in natural products, pharmaceuticals, ...agrochemicals and organic materials. In this regard, the recent resurgence of adopting green and sustainable electrochemistry in organic synthesis suggests that electrosynthesis is a promising strategy. Indeed, many new intriguing applications of synthesis and functionalization of indole derivatives by direct and redox‐mediated electrochemical means have been disclosed. In this review, we highlight the fundamental aspects, reaction scopes, synthetic applications and reaction mechanisms of the electrochemical synthesis and functionalization of indole derivatives.
The emergence of new catalytic strategies that cleverly adopt concepts and techniques frequently used in areas such as photochemistry and electrochemistry has yielded a myriad of new organic ...reactions that would be challenging to achieve using orthodox methods. Herein, we discuss the strategic use of anodically coupled electrolysis, an electrochemical process that combines two parallel oxidative events, as a complementary approach to existing methods for redox organic transformations. Specifically, we demonstrate anodically coupled electrolysis in the regio- and chemoselective chlorotrifluoromethylation of alkenes.
Vicinal diamines are an important structural motif in bioactive natural products and pharmaceutical intermediates. Herein, an environmentally friendly and efficient electrochemical approach to ...azidoacetamides, as one variant of vicinal diamines, has been developed. This reaction features mild conditions and broad substrate scope, without the use of any chemical oxidant or transition-metal catalysts. The obtained vicinal azidoacetamides could be conveniently converted into various other vicinal diamine derivatives.
Electrochemical oxygen reduction could proceed via either 4e
-pathway toward maximum chemical-to-electric energy conversion or 2e
-pathway toward onsite H
O
production. Bulk Pt catalysts are known as ...the best monometallic materials catalyzing O
-to-H
O conversion, however, controversies on the reduction product selectivity are noted for atomic dispersed Pt catalysts. Here, we prepare a series of carbon supported Pt single atom catalyst with varied neighboring dopants and Pt site densities to investigate the local coordination environment effect on branching oxygen reduction pathway. Manipulation of 2e
or 4e
reduction pathways is demonstrated through modification of the Pt coordination environment from Pt-C to Pt-N-C and Pt-S-C, giving rise to a controlled H
O
selectivity from 23.3% to 81.4% and a turnover frequency ratio of H
O
/H
O from 0.30 to 2.67 at 0.4 V versus reversible hydrogen electrode. Energetic analysis suggests both 2e
and 4e
pathways share a common intermediate of *OOH, Pt-C motif favors its dissociative reduction while Pt-S and Pt-N motifs prefer its direct protonation into H
O
. By taking the Pt-N-C catalyst as a stereotype, we further demonstrate that the maximum H
O
selectivity can be manipulated from 70 to 20% with increasing Pt site density, providing hints for regulating the stepwise oxygen reduction in different application scenarios.
Organic radicals are generally short-lived intermediates with exceptionally high reactivity. Strategically, achieving synthetically useful transformations mediated by organic radicals requires both ...efficient initiation and selective termination events. Here, we report a new catalytic strategy, namely, bimetallic radical redox-relay, in the regio- and stereoselective rearrangement of epoxides to allylic alcohols. This approach exploits the rich redox chemistry of Ti and Co complexes and merges reductive epoxide ring opening (initiation) with hydrogen atom transfer (termination). Critically, upon effecting key bond-forming and -breaking events, Ti and Co catalysts undergo proton transfer/electron transfer with one another to achieve turnover, thus constituting a truly synergistic dual catalytic system.
Organofluorine compounds find extensive application in the fields of agrochemicals, pharmaceuticals, materials science, and molecular imaging. Introducing fluorine atoms can provide organic compounds ...with unique physicochemical properties or improve their biological activity. Although significant progress has been made in the chemical synthesis of fluorine‐containing compounds, achieving selective fluorination under mild conditions remains extremely challenging. Introducing biocatalytic approaches in organofluorine chemistry is an important strategy given their high efficiency, selectivity, and environmental friendliness. In this review, we present the discovery of fluorinated natural products and fluorinases, the crystal structure and the directed evolution of fluorinases, with a focus on recent advances in the enzymatic synthesis of fluorine‐containing compounds in recent years. It is hoped that this review will help to promote the field of biocatalytic organofluorine compound synthesis.
Organofluorine compounds play a crucial role in agrochemicals, pharmaceuticals, and materials science. Biocatalysis has emerged as an essential strategy in the synthesis of fluorinated molecules under mild conditions. This review mainly focused on recent advances in the enzymatic synthesis of fluorine‐containing compounds. Furthermore, the identification of fluorinated natural products and fluorinases, the crystal structure and the directed evolution of fluorinases were discussed.
The stereoselective synthesis of chlorotrifluoromethylated pyrrolidines was achieved using anodically coupled electrolysis, an electrochemical process that combines two parallel oxidative events in a ...convergent and productive manner. The bench‐stable and commercially available solids CF3SO2Na and MgCl2 were used as the functional group sources to generate CF3. and Cl., respectively, via electrochemical oxidation, and the subsequent reaction of these radicals with the 1,6‐enyne substrate was controlled with an earth‐abundant Mn catalyst. In particular, the introduction of a chelating ligand allowed for the ene–yne cyclization to take place with high stereochemical control over the geometry of the alkene group in the pyrrolidine product.
The stereoselective synthesis of chlorotrifluoromethylated pyrrolidines was achieved using anodically coupled electrolysis in the presence of a Mn catalyst. The bench‐stable and commercially available solids CF3SO2Na and MgCl2 were used as functional‐group sources. The introduction of a chelating ligand allowed for the ene–yne cyclization to take place with high stereoselectivity.
Alkyl chlorides are common functional groups in synthetic organic chemistry. However, the engagement of unactivated alkyl chlorides, especially tertiary alkyl chlorides, in transition-metal-catalyzed ...C–C bond formation remains challenging. Herein, we describe the development of a TiIII-catalyzed radical addition of 2° and 3° alkyl chlorides to electron-deficient alkenes. Mechanistic data are consistent with inner-sphere activation of the C–Cl bond featuring TiIII-mediated Cl atom abstraction. Evidence suggests that the active TiIII catalyst is generated from the TiIV precursor in a Lewis-acid-assisted electron transfer process.
Benzoxathiazine dioxide, as a bioisostere of the clinically widely used diazoxide, exhibits interesting biological activity. However, limited success has been achieved in terms of its concise and ...direct synthesis. We report herein a facile electrochemical migratory cyclization of N‐acylsulfonamides to access a diverse array of benzoxathiazine dioxides. The inclusion of electrochemistry is crucial for realizing such a novel transformation, which is substantiated both by the experiments and density‐functional‐theory calculations.
Electrochemical migratory cyclization of N‐acylsulfonamides has been developed for the facile preparation of a diverse array of biologically interesting yet synthetically challenging benzoxathiazine dioxides.
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