Synlett

Catalytic transformations of alkenes via the metal-hydride hydrogen atom transfer (MHAT) mechanism have notably advanced synthetic organic chemistry. This Account focuses on MHAT/radical-polar crossover (MHAT/RPC) conditions, offering a novel perspective on generating electrophilic intermediates and facilitating various intramolecular reactions. On using cobalt hydrides, the MHAT mechanism displays exceptional chemoselectivity and functional group tolerance, making it invaluable for the construction of complex biologically relevant molecules under mild conditions. Recent developments have enhanced regioselectivity and expanded the scope of MHAT-type reactions, enabling the formation of cyclic molecules via hydroalkoxylation, hydroacyloxylation, and hydroamination. Notably, the addition of an oxidant to traditional MHAT systems enables the synthesis of rare cationic alkylcobalt(IV) complexes, bridging radical mechanisms to ionic reaction systems. This Account culminates with examples of natural product syntheses and an exploration of asymmetric intramolecular hydroalkoxylations, highlighting the ongoing challenges and opportunities for future research to achieve higher enantioselectivity. This comprehensive study revisits the historical evolution of the MHAT mechanism and provides a groundwork for further innovations on the synthesis of structurally diverse and complex natural products.1 Introduction2 Intramolecular Hydroalkoxylation and Hydroacyloxylation Reactions3 Intramolecular Hydroamination Reactions4 Intramolecular Hydroarylation Reactions5 Deprotective Cyclization6 Asymmetric Intramolecular Hydroalkoxylation7 Conclusion

Synlett 2024; 35: V-DOI: 10.1055/s-0043-1774929Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals:Table of contents

is an Executive Vice President at Osaka University and a full Professor at the Graduate School of Science. He received his B.Sc. in Chemistry from the Faculty of Science, Osaka University in 1982, and his Ph.D. in Chemistry from the same university in 1987. After working as a Research Fellow of the Japan Society for the Promotion of Science for about one year, he became an Assistant Professor at Faculty of Science, Osaka University in 1988. In 1994, he joined the Department of Chemistry at Columbia University as a Research Fellow. He was promoted to Lecturer in 1996, Associate Professor in 1998, and Full Professor in 2004 at Graduate School of Science, Osaka University. From 2020 to 2024, he was the Dean of the Graduate School of Science, Osaka University. In 2024, he was appointed as an Executive Vice President. His research interests include carbohydrate chemistry, organic synthesis, chemical biology, glycobiology, innate immunity, and targeted radionuclide therapy. He received the Chemical Society of Japan Award For Young Chemists in 1994, the Chemical Society of Japan Award for Creative Work in 2011, Honorary Life Membership in the International Endotoxin and Innate Immune Society in 2021, and the Chemical Society of Japan Award in 2024.

Synlett 2024; 35: A103-A117DOI: 10.1055/s-0043-1763988Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals:Table of contents

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 Introduction2 Reaction Design of Hydrofluorination3 Regio- and Enantioselective Hydrofluorination4 Asymmetric Amplification5 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.

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.

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.