Palladium complexes immobilized onto generation 0-3 PAMAM dendrimers supported on silica were used as catalysts for the carbonylation of iodobenzene in methanol to form methyl benzoate. High yields were obtained and the catalyst was recycled 4-5 times without significant loss of activity. The carbonylation reaction was found to be applicable to a variety of iodoarenes regardless of the nature of the substituent.
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http://dx.doi.org/10.1021/jo020271n | DOI Listing |
Chem Commun (Camb)
March 2025
Department of Chemistry and Shenzhen Grubbs Institute, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
The mechanism and origin of enantioselectivity of palladium-catalyzed redox-relay Heck arylation of 1,1-disubstituted homoallylic alcohols were investigated computationally. The computed mechanism consists of an initial migratory insertion, followed by a β-hydride elimination, and a subsequent re-insertion/elimination process to yield an enol intermediate, which tautomerizes to the more stable carbonyl product. Results from DFT calculations suggest that the key enantiodetermining step is the reinsertion of an alkene intermediate into the Pd-H bond, but not the initial migratory insertion of the substrate into the Pd-Aryl species.
View Article and Find Full Text PDFPhys Chem Chem Phys
March 2025
Voevodsky Institute of Chemical Kinetics and Combustion, SB RAS, 3, Institutskaya str., Novosibirsk, 630090, Russia.
This study focuses on primary radical ionic species created in liquid carbonates upon high-energy radiation. We studied the radiation-induced fluorescence intensity decays observed from solutions of luminophores in dimethyl, diethyl, ethylene, and propylene carbonates. Based on the effects of external magnetic and electric fields on the fluorescence decays on a timescale of 1-60 ns and quantum chemical calculations, we found that in all studied carbonates, solvent ionization was rapidly followed by the formation of comparatively long-lived positive charge and unpaired electron spin carriers.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
March 2025
Julius-Maximilians-Universitat Wurzburg, Department of Chemistry, Am Hubland, 97074, Würzburg, GERMANY.
While existing literature has primarily focused on carbene-stabilized amino- and arylborylenes of the form [(carbene)BR] (R = substituent), herein we report the generation and metallomimetic reactivity of the first carbene-stabilized alkylborylene [(CAACMe)BCy] (CAACMe = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene, Cy = cyclohexyl. Furthermore, the transition metal-like decarbonylation reactions of a borylene complex, [(CAACMe)BCy(CO)], derived from borylene [(CAACMe)BCy] and CO, are described. Additional findings described include (i) the identification of the coordination stages of the ligand to boron towards forming complexes [(CAACMe)BCyL] in the reduction route from starting material [(CAACMe)BCyBr2] and in the photolysis route from carbonyl complex [(CAACMe)BCy(CO], and (ii) insights from quantum-chemical computations regarding the molecular and electronic structure of the borylene at various stages.
View Article and Find Full Text PDFChemistry
March 2025
Chinese Academy of Sciences Fujian Institute of Research on the Structure of Matter, State Key Laboratory of Structural Chemistry, CHINA.
Dimethyl carbonate and dimethyl oxalate are competitive products of the carbonylation reaction of methyl nitrite (MN) under Pd-based catalysts. The chemo-selectivity is influenced not just by the thermodynamic constraints of reaction conditions but also by the electronic structures of catalysts. Lewis acid sites are extensively employed to modulate the electronic structures of Pd active sites for kinetic carbonate production, but their precise role remains unclear.
View Article and Find Full Text PDFJ Am Chem Soc
March 2025
Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States.
The electrocatalytic utilization of oxidized nitrogen waste for C-N coupling chemistry is an exciting research area with great potential to be adopted as a sustainable method for generation of organonitrogen molecules. The most widely used C-N coupling reaction is reductive amination. In this work, we develop an alternative electrochemical reductive amination reaction that can proceed in neutral aqueous electrolyte with nitrite as the nitrogenous reactant and via an oxime intermediate.
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