Hydrogenation of Quinones to Hydroquinones under Atmospheric Pressure Catalyzed by a Metal–Ligand Bifunctional Iridium Catalyst

Abstract

A general method for the hydrogenation of quinones to hydroquinones under atmospheric pressure has been developed. In the presence of [Cp*Ir(2,2′-bpyO)(H 2 O)] (0.5−1 mol %), a range of products were obtained in high yields. Furthemore, the expansion of this catalytic system to the hydrogenation of 1,4-benzoquinone diimines was also presented. Functional groups in the bpy ligand were found to be crucial for the catalytic activity of iridium complexes.

Selective Conversion of Glycerol to Lactic Acid in Water via Acceptorless Dehydrogenation Catalyzed by a Water-Soluble Metal–Ligand Bifunctional Iridium Catalyst

“…Fujita, Yamaguchi, and co-workers have designed a series of Cp*Ir complexes bearing a bipyridonate or α-hydroxybipyridine ligand, exhibiting highly catalytic activity for acceptorless dehydrogenation of N-heterocycles and alcohols, and hydrogen production from an alcohol–water solution based on the concept of ligand-promoted dehydrogenation. Encouraged by their research, we have also reported that such complexes are effective catalysts for the hydrogen (or deuterium) autotransfer process, acceptorless dehydrogenative cyclization, and hydrogenation and designed a series of new metal–ligand bifunctional catalysts . Chen and Ke’s groups have also reported two Cp*Ir complexes bearing a hydroxybipyridine ligand for the hydrogen autotransfer process .…”

Selective N-Alkylation of Aminobenzenesulfonamides with Alcohols for the Synthesis of Amino-(N-alkyl)benzenesulfonamides Catalyzed by a Metal–Ligand Bifunctional Ruthenium Catalyst

“…Despite significant advances, most research studies only focus on the N-alkylation of relatively simple reactants bearing a single amino group as nucleophiles. We have reported a series of green reactions based on hydrogen (or deuterium) autotransfer process, acceptorless dehydrogenation, and hydrogenation . In particular, we reported the selective N-alkylation of aminobenzenesulfonamides with alcohols to amino-( N -alkyl)­benzenesulfonamides catalyzed by iridium complex [Cp*IrCl 2 ] 2 and Cp*Ir@CTF (Scheme , left two complexes) .…”

Poly(2,2′-Bibenzimidazole)–Supported Iridium Complex: A Recyclable Metal–Polymer Ligand Bifunctional Catalyst for the N-Methylation of Amines with Methanol

“…We developed a series of environmentally benign reactions based on a hydrogen autotransfer process and acceptorless dehydrogenation and hydrogenation using iridium or ruthenium catalysts. In particular, we demonstrated the design and X-ray characterization of an iridium complex bearing a functional 2,2′-bibenzimidazole ligand [Cp*Ir(2,2′-BiBzIm)Cl][Cl] (BiBzIM = bibenzimidazole), and application of it as a homogeneous catalyst for the N -methylation of amines with methanol in the presence of Cs 2 CO 3 (0.3 equiv) (Scheme , left structure) .…”