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We recently achieved an oxidation-initiated photoenzymatic enantioselective hydrosulfonylation of olefins through the utilization of a new Gluconobacter ene-reductase mutant (GluER-W100F-W342F). Our method simplifies the reaction system by eliminating the need for a cofactor regeneration mixture and, in contrast with previous photoenzymatic systems, does not depend on the formation of an electron donor–acceptor (EDA) complex between the substrates and enzyme cofactor. Moreover, the GluER variant exhibits good substrate compatibility and excellent enantioselectivity. Mechanistic investigations indicate that a tyrosine-mediated HAT process is involved and support the proposed oxidation-initiated mechanism. In this Synpacts article, we discuss the conceptual framework that led to the discovery of this reaction and reflect on the key aspects of its development.

1 Introduction

2 Conceptual Background

2.1 Intramolecular Photoenzymatic Reactions via Single-Electron Reduction

2.2 Intermolecular Photoenzymatic Reactions via Single-Electron Reduction

3 The Development of the Process

4 Conclusion

An efficient Michael addition of 4-hydroxycoumarins to α,β-unsaturated 2-acyl imidazoles catalyzed by Ni(OTf)₂ as a Lewis acid has been developed. A series of 4-hydroxycoumarin derivatives were obtained in excellent yields (up to 96%) with a 2 mol% catalyst loading under mild conditions. Additionally, when a chiral-at-metal rhodium complex was used as the catalyst, moderate enantioselectivity was observed (74% ee).

In this study, we proposed a novel electrochemical dehydrogenative synthetic method for preparing 2-substituted quinoxalines by intermolecular cyclization of aryl alkyl ketones and o-phenylenediamines. This method gave various quinoxalines in yields ranging from 35% to 71%. This novel protocol employs mild reaction conditions and offers moderate to excellent yields, a wide substrate scope, and broad functional-group compatibility. Furthermore, a late-stage functionalization and the wide substrate scope demonstrated the synthetic utility of this protocol.

While enantioselective hydrofluorination methods for activated alkenes represent a notable advance, the resultant enantiomeric excesses remain largely moderate, indicating the necessity for enhancements in precision, efficiency, and scope. We have recently developed an innovative nickel hydride catalytic system that enables regio- and enantioselective C–F bond formation with unactivated alkenes. By utilizing specially designed Bn-BOx ligands for improved selectivity, our approach demonstrates exceptional efficiency and selectivity with β,γ-alkenyl amide substrates. This breakthrough enhances the synthesis of organofluorine compounds, marking a significant advancement in organic synthesis.

1 Introduction

2 Reaction Design of Hydrofluorination

3 Regio- and Enantioselective Hydrofluorination

4 Asymmetric Amplification

5 Conclusions

An electrochemical variant of the alcohol-based oxidative Passerini reaction is reported here. It relies on an indirect anodic oxidation process followed by a three-component coupling, in which TEMPO serves as a key redox mediator. This electrochemical approach permits to operate without the need for a metal catalyst nor oxygen atmosphere and allows the use of nonactivated alcohols as reaction partners. It could be applied to the preparation of good variety of α-acyloxy-carboxamides in yields ranging from 24% to 80%.

Herein, the preparation and characterization of three Ru-based heterogeneous photocatalysts supported on ordered mesoporous silica materials are reported. The photocatalytic activity of these catalysts was evaluated through oxidation, reduction, cycloaddition, and carboxylation reactions and their efficiencies are comparable to the parent [Ru(bpy)₃]Cl₂ under homogeneous conditions. These photocatalysts are efficiently recovered even after five reaction cycles offering new opportunities in sustainable chemistry.

Organic cagelike frameworks are important and versatile skeletons for developing prospective energetic compounds because of their high intrinsic density, symmetry, stability, and derivability. Herein, we show the construction of three novel cagelike frameworks including dioxaadamantane, dioxaproadamantane, and dioxatwistane from 9-oxabicyclo[3.3.1]nonane-2,6-diene. In addition, their energetic derivatives were also prepared and characterized. Compared with our previous works, the introduction of more oxygen atoms into the framework gives the corresponding energetic derivative a better oxygen balance, significantly higher density, and detonation properties. These results imply that the oxygen-containing framework has the potential to be used for preparing new 3D energetic compounds with superior energy performance.

A practical method is introduced for the catalytic conversion of terminal alkynes into α-substituted vinyl boronic esters. The process employs catalytic amounts of nanoparticle-supported gold catalysts and catalytic amounts of copper to effect the overall transformation.

We report a visible-light-driven metal-free and photocatalyst-free protocol for the synthesis of phenanthrenes through the intramolecular cyclization of chalcones. The transformation proceeds through light irradiation and base- and oxygen-based promotion, and enables the generation of a series of phenanthrenes. The further functionalization of an as-synthesized phenanthrene to afford a fluorescent molecule was explored.

The modification of biomolecules, particularly peptides, has garnered considerable attention from researchers, effectively serving as a connection between chemistry and biology. The modification of peptides can facilitate, among others, the generation of peptide drugs, antibody–drug conjugates, and probes for molecular imaging. Herein, we have carefully curated reactions and chemical transformations of bioactive peptide sequences equipped with histidine amino acids that are conducive for biological applications. This Account also highlights strategies for the chemical modification of histidine that might capture the imagination of both peptide researchers and synthetic chemists.

1 Introduction

2 Histidine Modification in Bioactive Peptides and Proteins

3 Remote Bioactive Peptides and Protein Modification Adjacent to Histidine

4 Conclusions and Future Directions