Decarbonylation of 1,2-Diketones to Diaryl Ketones via Oxidative Addition Enabled by an Electron-Deficient Au–Pd Nanoparticle Catalyst

Abstract

Decarbonylation via oxidative addition has been widely studied as a challenging and beneficial transformation using various carbonyl compounds. To our knowledge, however, diaryl 1,2-diketones have not been subjected to this type of decarbonylation thus far. Herein, we report a versatile 1,2-diketone decarbonylation to afford diaryl ketones via oxidative addition by utilizing a CeO 2 -supported Au−Pd alloy nanoparticle catalyst. According to a thorough catalyst characterization, kinetic evaluation, and control experiment, the high catalytic performance is attributed to the promotion of the reductive elimination as the turnover-limiting step by electron-deficient Pd(0) species due to their strong interaction with CeO 2 and to the suppression of catalyst deactivation by alloying Pd with Au. The present work provides a methodology for activating inert C−C bonds via oxidative addition based on the use of a multifunctional supported nanoparticle catalyst.

Formal Decarbonylation of 1,2-Diketones Enabled by Synergistic Catalysis of Lewis Acid–Base Pairs and Redox Properties in CeO2

“…Halogenated benzils, including 4,4′-fluoro, 4,4′-chloro, 4,4′-bromo, and 4,4′-iodo benzils, exhibited good tolerance without producing dehalogenated products ( 1g – 1j ). Noteworthily, the present system enabled the decarbonylation of ortho -substituted ( 1d ) and high-reactive halogenated ( 1h – 1j ) 1,2-diketones, which could not be realized using our previous direct decarbonylation system . The unsymmetrical benzils with electron-donating functional groups ( 1k and 1l ) and an electron-withdrawing group ( 1m ) also underwent this formal decarbonylation.…”

“…In spite of its utility, there are limited studies on the decarbonylation of diaryl 1,2-diketones to produce diaryl ketones . We previously reported the first practical diaryl 1,2-diketone decarbonylation via oxidative addition using a supported Au–Pd alloy nanoparticle catalyst . However, a stoichiometric amount of CO and a considerable amount of biphenyl byproducts were inevitably produced during the process owing to the Pd-catalyzed oxidative addition step (Scheme c).…”

Formal 1,2-Diketone Decarbonylation Enabled by Synergistic Catalysis of Lewis Acid-Base Pairs and Redox Properties in CeO2

“…Noteworthily, the present system enabled the decarbonylation of ortho-substituted (1d) and high-reactive halogenated (1h-1j) 1,2-diketones, which could not be realized using our previous direct decarbonylation system. [8] The unsymmetrical benzils with electron-donating functional groups (1k and 1l) and an electron-withdrawing group (1m) alsounderwent this formal decarbonylation. This system can be used for the decarbonylation of 2,2′-naphthyl-substituted 1,2diketones (1n).…”

“…[7] We previously reported the first practical diaryl 1,2-diketone decarbonylation via oxidative addition using a supported Au-Pd alloy nanoparticle catalyst. [8] However, a stoichiometric amount of CO and considerable amount of biphenyl byproducts were inevitably produced during the process owing to the Pd-catalyzed oxidative addition step (Scheme 1c). Additionally, the catalyst was hardly reused due to the sintering of Au-Pd alloy nanoparticles and/or organic compound adsorption to cover the active sites.…”

Heterogeneously Catalyzed Thioether Metathesis by a Supported Au–Pd Alloy Nanoparticle Design Based on Pd Ensemble Control

“…Au4.4−Pd1/TiO2 was confirmed to function as the heterogenous catalyst by a hot filtration test and inductively coupled plasmaatomic emission spectroscopy (ICP-AES) (Figure S3), and the catalyst could be reused several times (Figure S4). 9 Scheme 2a summarizes the substrate scope of Au4.4−Pd1/TiO2-catalyzed C-S bond metathesis of diaryl thioethers. Symmetrical methyl-substituted thioethers at the para, meta, and ortho positions afforded the corresponding unsymmetrical thioethers in good yields (1ab-1ad).…”