Ruthenium‐Catalyzed Dehydrogenation Through an Intermolecular Hydrogen Atom Transfer Mechanism

Abstract

The direct dehydrogenation of alkanes is among the most efficient ways to access valuable alkene products. Although several catalysts have been designed to promote this transformation, they have unfortunately found limited applications in fine chemical synthesis. Here, we report a conceptually novel strategy for the catalytic, intermolecular dehydrogenation of alkanes using a ruthenium catalyst. The combination of a redox‐active ligand and a sterically hindered aryl radical intermediate has unleashed this novel strategy. Importantly, mechanistic investigations have been performed to provide a conceptual framework for the further development of this new catalytic dehydrogenation system.

The Journey of Ni(I) Chemistry

“…Besides the above‐mentioned examples involving phosphines or NHC‐type ligands, non‐innocent ligands are emerging players in catalysis and have been shown to be more involved in electronic processes compared to classic spectator ligands [50,51] . Here, we report a selection of those that have contributed to the field of Ni(I)‐catalyzed cross‐couplings [20] …”

“…[49] Besides the above-mentioned examples involving phosphines or NHC-type ligands, non-innocent ligands are emerging players in catalysis and have been shown to be more involved in electronic processes compared to classic spectator ligands. [50,51] Here, we report a selection of those that have contributed to the field of Ni(I)-catalyzed cross-couplings. [20] Nitrogen-chelating ligands excel at stabilizing open-shell nickel species due to their strong σ-donation and π-accepting properties [50] and for instance, pyridine-supported nickel species are proposed in many important organic transformations, such as Negishi, [52,53] cross-electrophile couplings, [54] and others.…”

Acetone Serving as a Solvent and Interaction Partner Promotes the Direct Olefination of N-Tosylhydrazones under Visible Light

“…The intramolecular synthesis of olefins from ketones continues to attract extensive attention because the synthesis of natural products or other important fine chemicals often requires the installation of double bond without adding carbon. − The most traditional and robust methods to prepare olefins via the intramolecular carbon–carbon double bond formation include Shapiro and Bamford–Stevens reactions, which serve as highly convenient and robust strategies. − However, these approaches are limited to the use of air-sensitive strong bases or Grignard reagents, such as n -BuLi, and were accompanied by the formation of equivalent metal wastes (Scheme a). Therefore, several improved protocols have been developed in recent years to overcome these limitations. − Fernandes and coworkers developed an efficient method allowing access to olefins from ketones directly via oxorhenium catalysis, which reacts under a high temperature at 170 °C . In addition, Wang and coworkers disclosed that the palladium-catalyzed oxidative borylation of N -tosylhydrazones could also afford olefins in toluene at 90 °C .…”

Non‐Symmetrical Tetraaryl‐α‐Diimines via Transimination: A Promising Route for Non‐Symmetrical 1,3,4,5‐Tetraarylimidazolium Chlorides

“…Synthetic procedures for symmetrical N,N’‐tetraaryl‐α‐diimines (Ar−N=C(Ar)−C(Ar)=N−Ar) often involve the condensation of an α‐diketone with aryl amines [19–21] . Also, ytterbium [22] (Scheme 1A) or sodium cyanide [23] (Scheme 1B) facilitated aldimine cross coupling routes were known to yield symmetrical α‐diimines.…”