Work

Parts‐Per‐Million Level Loading Cyclometalated Ru(II)‐NHC Catalyzed Selective Oxidation of Olefins to Carbonyls

Year: 2024

Type: article

Abstract: Oxidative cleavage of olefins is a useful reaction in organic synthesis. The most well‐known catalytic system is the osmium based Lemieux‐Johnson catalyst, which generally requires high catalyst loading and tends to suffer from rapid overoxidation to produce the acid predominantly. Hence, the development of a mild, general, and selective method toward the oxidative cleavage of alkenes to carbonyl compounds is highly desired. In this work, a highly efficient ruthenium‐based catalyst for olefin oxidation has been demonstrated by employing a fused π‐conjugated imidazo[1,5‐a]quinoxaline (ImQx) based NHC ligand with bidentate C(carbanion) CNHC motif. Strong C‐donor ligands, paired with a rigid backbone and ruthenium redox activity, provided exceptionally high catalytic activity and a long lifetime for olefin oxidation. Complex showed high catalytic activity and a long lifetime, TONs are several million. The catalyst tolerates numerous functional groups and can be applicable to challenging biomass, natural products, sugar, amino acids, and fatty acid‐derived substrates. Based on kinetic studies, thermodynamic activation parameters, and DFT study, the mechanistic finding demonstrated that [3+2] cycloaddition reaction is the key step in the oxidation process. The use of the by‐product NaIO3 in the catalytic efficiency has been disclosed for the first time.

Source: Chemistry - A European Journal

DOI: 10.1002/chem.202403135

Authors: Monuranjan Konwar, Tapashi Das, Animesh Das

Institution: Indian Institute of Technology Guwahati

Language: English

Topic: N-Heterocyclic Carbenes in Organic and Inorganic Chemistry

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: bronze