5-Hydroxymethylfurfural (HMF) has become a benchmark chemical as it can be obtained by the processing of renewable biomass, making its downstream modification an important topic both in industry and academia. Finding catalytic processes for the selective derivatization of HMF is challenging due to its reactivity, hence mild conditions are needed. Here we report the selective oxidative esterification of HMF to methyl 5-(hydroxymethyl)furan-2-carboxylate and to dimethyl furan-2,5-dicarboxylate (FDCM) under mild conditions using oxygen (from air) as oxidant. A synergetic effect between the used catalysts, cobalt oxide over nitrogen-doped carbon, and ruthenium over carbon catalysts was observed by catalytic and electron paramagnetic resonance measurements. Kinetic analysis revealed a first order dependence on substrate for the cobalt catalyst and an apparent zero order for the ruthenium catalysts. The conversion rates were improved by the use of perfluoroether as solvent, proving that the oxygen diffusion is the limiting factor in the system.
A family of six structurally related heteroleptic copper(I) complexes of the form of [Cu(N^N)(P^P)]+ bearing a 2,9-dimethyl-1,10-phenanthroline diimine (N^N) ligand and a series of electronically tunable xantphos (P^P) ligands have...
The redox activity of molecular phenazine catalysts has been previously exploited for aerobic oxidative amine homo-and cross-coupling reactions. In this contribution, we have extended the reaction scope of this novel type of organocatalyst and used them in the cross-dehydrogenative aza-Henry coupling of isoquinolines with nitromethane under aerobic conditions. Additionally, we have designed and prepared a novel porous organic polymer by cross-linking of tetrakis(4-bromophenyl)silane and dihydrophenazine through Pd-catalyzed Buchwald-Hartwig cross-coupling. This new type of heterogeneous catalyst, apart from being robust and easily reusable, also showed outstanding catalytic activities and improved selectivity compared to its molecular counterpart. A plausible reaction mechanism was proposed based on spectroscopic and kinetic measurements.
Catalytic allylation reactions are important methodologies to introduce the versatile allyl functionality into molecules to produce fine chemicals and synthetic building blocks. Since the first reports by Tsuji and Trost,...
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