Wenyi Chu

Efficient conversion of fructose into 5-hydroxymethylfurfural over WO3/reduced graphene oxide catalysts

A sustainable and efficient catalyst for converting carbohydrates to a renewable platform chemical 5-hydroxymethylfurfural (HMF) is the goal in the study of biomass recycling. Reduced graphene oxide-supported tungsten trioxide (WO3/RGO) as an acidic catalyst was synthesized through a one-step hydrothermal method, characterized via TEM, XPS, XRD and Raman spectroscopy and applied to the conversion of fructose to HMF. The WO3/RGO catalyst showed a highly efficient catalytic activity, and the yield of HMF could reach up to 84.2% with complete conversion of fructose. The catalyst could be reused five times with a slight decrease in activity. Further study indicated that WO3/RGO could also catalyze the conversion of cellulose, glucose and sucrose to HMF.

NIR luminescence of a series of benzoyltrifluoroacetone erbium complexes

A series of five β-diketone erbium complexes with various azacyclo-auxiliary ligands, namely, Er(Hbta)3(H2O)2 (1), Er(Hbta)3(bpy) (2), Er(Hbta)3(phen) (3), Er(Hbta)3(dpq) (4) and Er(Hbta)3(dppz) (5) (Hbta = benzoyltrifluoroacetone, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, dpq = pyrazino[2,3-f][1,10]phenanthroline, dppz = dipyrido[3,2-a:2′,3′-c]phenazine) have been isolated and characterized by X-ray crystallographic analysis. Near-infrared luminescence analysis reveals that all complexes 1–5 exhibit strong NIR luminescence of Er(III) ions around 1535 nm with the highest lifetime of 4.532 μs, quantum yield of 3.24 × 10−4 and broadband emission around 1.5 μm for complex 5, in which the azacyclo-auxiliary ligand absorbs and transfers the energy leading to complete quenching of the ligand-associated visible emission. The energy transfer processes among benzoyltrifluoroacetone, the Er(III) ion and the auxiliary ligands in complexes 1–5 have been investigated.

Palladium-catalyzed decarboxylative ortho-aroylation of N-acetyl-1,2,3,4-tetrahydroquinolines with α-oxoarylacetic acids

A mild, practical and efficient palladium-catalyzed decarboxylative ortho-aroylation of N-acetyl-1,2,3,4-tetrahydroquinolines with α-oxoarylacetic acids via C–H bond activation is described. This protocol provides efficient access to a series of C8-aroyl terahydroquinolines.

An effective and environment-friendly system for Cu NPs@RGO-catalyzed C–C homocoupling of aryl halides or arylboronic acids in ionic liquids under microwave irradiation

As an outstanding mesh catalyst support, reduced graphene oxide (RGO) has attracted enormous attention in recent years. Cu nanoparticles-RGO (Cu NPs@RGO) as a green catalyst was prepared through a green reduction method by ascorbic acid in N-methyl-2-pyrrolidone. The structure of prepared Cu NPs@RGO was characterized. The catalytic activity of Cu NPs@RGO was estimated. A green and efficient method for synthesizing symmetrical biaryl compounds was developed by Cu NPs@RGO-catalyzed Ullmann homocoupling of aryl halides or arylboronic acids in ionic liquids under microwave (MW) irradiation. The catalytic system could be recycled five times with slight loss of activity. Through this method, nine kinds of biaryls were prepared by homocoupling reaction of the corresponding aryl iodides, aryl bromides, aryl chlorides and aryl boronic acids in moderate to good yields.

Visible-Light-Induced Decarboxylation Coupling/Intramolecular Cyclization: A One-Pot Synthesis for 4-Aryl-2-quinolinone Derivatives

A visible-light-induced decarboxylation coupling/intramolecular cyclization is reported. The one-pot synthesis system provides mild, efficient, and atom economical access to the synthesis of 4-aryl-2-quinolinone derivatives. It is notable that the necessary oxidant in the traditional decarboxylation coupling is replaced by the visible-light irradiation in this paper. In addition, the HBV inhibitor is synthesized by the one-pot synthesis system in an atom economical manner.

Luminescent single molecule magnets of a series of β-diketone dysprosium complexes

A series of three luminescent single molecule magnets of β-diketone mononuclear dysprosium complexes, namely, Dy(tfa)3(H2O)2·Me2CO (1), Dy(tfa)3(bpy) (2) and Dy(tfa)3(phen) (3) (tfa = trifluoroacetylacetonate, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, C3H6O = Me2CO) have been isolated. Single-crystal X-ray analysis shows all the central Dy(III) ions are eight-coordinated adopting the coordination geometries of the distorted dodecahedron, bicapped trigonal prism and square antiprism for complexes 1–3, respectively. Magnetic analyses exhibit slow magnetic relaxation with the barrier heights (Ueff/kB) of 41 K, 33 K and 55 K for complexes 1–3, respectively. Photo-luminescent analysis reveal that complexes 1–3 exhibit the typical yellow luminescence of Dy(III) ions. The correlation between the structure and physical properties has been investigated.

Efficient symmetrical bidentate dioxime ligand-accelerated homogeneous palladium-catalyzed Suzuki–Miyaura coupling reactions of aryl chlorides

A series of N,O-bidentate ligands were synthesized using the Vilsmeier–Haack reaction and oximation. 2,5-Dihydroxyterephthalaldehyde dioxime (L8) as an efficient N,O-symmetrical bidentate ligand was prepared from hydroquinone. It was studied as a high activity ligand for palladium-catalyzed Suzuki–Miyaura cross-coupling reactions of aryl chlorides with arylboronic acids under mild conditions. The coupling reactions were performed in the presence of PdCl2 as the catalyst, L8 as the ligand, Na2CO3 as the base, PEG-400 as the PTC and in ethanol/water (1 : 1) as an environmentally benign solvent at 85 °C. Plentiful biaryls were obtained by the optimized reaction with good yields at a low palladium loading of 0.20 mol%.

Visible-Light-Assisted Cobalt-2-(hydroxyimino)-1-phenylpropan-1-one Complex Catalyzed Pd/Cu-Free Sonogashira-Hagihara Cross-Coupling Reaction

An effective and inexpensive strategy for the Co(C9H9NO2)3 catalyzed Sonogashira–Hagihara cross‐coupling reaction of aryl bromides containing electron‐rich and electron‐poor substituents with terminal alkynes was demonstrated. The reaction proceeded smoothly in the presence of ethylene glycol as additive and K2CO3 as base in DMF under visible light illumination, and 23 alkyne products were afforded in moderate to excellent yields, including four new diaryl ethynes. Compared with the high‐cost palladium catalyst, cobalt is an inexpensive catalyst with a preponderance of technologized production, and the palladium/copper‐free catalytic system not only provided an efficient process with mild reaction conditions, but also enhanced the substrate group tolerance.

Efficient nickel(II) naringenin-oxime complex catalyzed Mizoroki–Heck cross-coupling reaction in the presence of hydrazine hydrate

A novel nickel(II) naringenin-oxime complex was designed, synthesized and characterized. Therein, the nickel(II) naringenin oxime complex as an efficient catalyst was used in Mizoroki–Heck coupling reactions of aryl halides containing electron-rich and electron-deficient substituents with styrene, methyl acrylate and divinylbenzene (DVB), respectively. The reaction proceeded efficiently under alkaline conditions in the presence of 0.30 mol% of the Ni(II) naringenin oxime complexand N2H4·H2O as the reductant in EtOH at 80 °C, and 32 alkene products were afforded in moderate to excellent yields, containing four new olefins. The new catalytic system not only provided an inexpensive and efficient process with greener conditions, but also broadened the reaction scope.

DBU-Based Dicationic Ionic Liquids Promoted Esterification Reaction of Carboxylic Acid with Primary Chloroalkane Under Mild Conditions

A series of DBU-based (DBU = 1, 8-diazabicyclo [5.4.0] undec-7-ene) dicationic ionic liquids with different anions were successfully synthesized by the reaction of DBU and 1, 6-dichlorohexane. Therein, the dicationic ionic liquid 1, 1′-(hexane-1, 6-diyl)bis(1, 8-diazabicyclo [5.4.0]undec-7-enium) dichlorine (IL-1) was successfully employed as an efficient catalyst in esterification reaction of carboxylic acids with primary chloroalkanes under mild conditions without any additional basic reagents. Moreover, the optimum catalyst could be efficiently reused for five times without any significant change on the catalytic effect. The improved protocol is not only efficient, but also green and pollution-free.Graphical Abstract