Visible-Light-Promoted Iridium(III)-Catalyzed Acceptorless Dehydrogenation of N-Heterocycles at Room Temperature

Abstract

An effective visible-light-promoted iridium(III)-catalyzed hydrogen production from N-heterocycles is described. A single iridium complex constitutes the photocatalytic system playing a dual task, harvesting visible-light and facilitating C–H cleavage and H 2 formation at room temperature and without additives. The presence of a chelating C–N ligand combining a mesoionic carbene ligand along with an amido functionality in the Ir III complex is essential to attain the photocatalytic transformation. Furthermore, the Ir III complex is also an efficient catalyst for the thermal reverse process under mild conditions, positioning itself as a proficient candidate for liquid organic hydrogen carrier technologies (LOHCs). Mechanistic studies support a light-induced formation of H 2 from the Ir–H intermediate as the operating mode of the iridium complex.

Biocatalytic and Chemo-Enzymatic Synthesis of Quinolines and 2-Quinolones by Monoamine Oxidase (MAO-N) and Horseradish Peroxidase (HRP) Biocatalysts

“…Thus, the development of practical and mild transformations that allow the synthesis of these aromatic rings from readily available starting materials is highly desirable. From a retrosynthetic standpoint, the oxidation of 1,2,3,4-tetrahydroquinolines (THQs) is the straightforward way to obtain aromatic quinolines (Figure b) . Such an approach enables the synthesis of these heteroaromatic compounds with substitution patterns and/or functional groups that are otherwise difficult to insert via traditional aromatic functionalization reactions.…”

Sustainable and Mild Catalytic Acceptorless Dehydrogenations

“…[33], [34] Despite noteworthy improvements to achieve the CAD process using a binary catalyst system, the demanding dehydrogenation of saturated hydrocarbons is still a challenging task. [34], [35], [36], [37] Scheme 2 Palladium-catalyzed Acceptorless Dehydrogenation of N-Heterocycles.…”

“…Despite noteworthy improvements to achieve the CAD process using a binary catalyst system, the demanding dehydrogenation of saturated hydrocarbons is still a challenging task. [34][35][36][37] Scheme 2 Borane-catalyzed acceptorless dehydrogenation of N-heterocycles…”

Visible-light-driven SAQS-catalyzed aerobic oxidative dehydrogenation of alkyl 2-phenylhydrazinecarboxylates

“…Besides, several photo-dehydrogenation reactions were reported. [34][35][36] Anthraquinone (AQ) derivatives, which are useful components in medicines, were employed as organic catalysts in photo-redox or photooxygenation reactions to produce reactive oxygen species (ROS). 37 In particular, sodium anthraquinone sulfonate (SAQS) has been effectively used as a benecial catalyst for numerous chemical transformations such as oxidation of alcohols, asymmetric aldol reactions, and bromination.…”