Maolin Yuan

Aqueous Phase Hydrogenation of Quinoline to Decahydroquinoline Catalyzed by Ruthenium Nanoparticles Supported on Glucose‐Derived Carbon Spheres

A new ruthenium catalyst supported on glucose‐derived carbon spheres was prepared by using the impregnation method and then characterized by X‐ray photoelectron spectroscopy, XRD, TEM, SEM, FTIR, and solid‐state 13C MAS NMR techniques. With water as the environmentally friendly solvent, the conversion of quinoline and the selectivity toward decahydroquinoline could reach 98.2 and 95.2 %, respectively, under mild conditions (reaction temperature=393 K and H2 pressure=2.0 MPa). The catalyst could be recycled thrice without decrease in activity and selectivity. The excellent catalytic performance of this catalyst may be attributed to the hydrogen bond between the hydroxyl group of the support surface and the nitrogen atom in quinoline as well as to the π–π interaction between the organic support and quinoline.

Carbonylation of Aryl Halide Catalyzed by Active-carbon Supported Ionic Liquid-phase Palladium Catalyst

Abstract Highly dispersed supported ionic liquid-phase palladium catalyst was prepared and its catalytic performances for carbonylation of aryl halide were investigated. Active-carbon supported ionic liquid-phase palladium catalyst was characterized by XRD, high-resolution TEM (HRTEM), and XPS. The results showed that the active-carbon supported ionic liquid-phase palladium catalyst was reduced to zero valence and that the average particle diameter of the Pd crystallites was less than 5 nm. A thin ionic liquid film was observed on the surface of the catalyst. The results indicated that the supported ionic liquid-phase palladium catalyst exhibited higher activity in the carbonylation of aryl halides compared with the corresponding organic-ionic liquid biphasic system. Under the optimum reaction conditions: 140 °C, p CO = 4.0 MPa, n (PhI): n (Pd) = 10528:1, the turnover frequency (TOF) of 4926 h −1 was achieved for ethyl benzoate with the conversion of 99.3%, and the selectivity for forming ethyl benzoate was more than 99%.

Construction of pincer-type symmetrical ruthenium(II) complexes bearing pyridyl-2,6-pyrazolyl arms: catalytic behavior in transfer hydrogenation of ketones

Convenient synthesis of four new distorted octahedral ruthenium(II) complexes (1, 2, 3, 4) having general molecular formula [RuCl2LPAr3] (L = pyridine-based tridentate ligands not containing N–H bonds) is described. Their composition and structure were determined by elemental analysis and NMR spectra, and complexes 2 and 4 were also identified by X-ray single-crystal diffraction. All ruthenium(II) complexes exhibited good to excellent catalytic activity in the transfer hydrogenation of ketones. Among them, complex 4 achieved the highest final TOF value of 51 600 h−1 for a high molar ratio of substrate to catalyst (2000 : 1).

Highly Regioselective and Active Rhodium/Bisphosphite Catalytic System for Isomerization–Hydroformylation of 2-Butene

The formation of linear aldehyde from isomerization–hydroformylation of 2-butene represents an important subject and current task in industry. Both high activity and excellent regioselectivity were achieved in the rhodium-catalyzed 2-butene isomerization–hydroformylation with 2,2′-bis(dipyrrolylphosphinooxy)-1,1′-(±)-binaphthyl (1) as ligand. Bulky phosphite with electron-withdrawing pyrrol groups dramatically improved the selectivity of linear product, and a good yield of 90.5% aldehydes was obtained with an excellent linear aldehyde regioselectivity of 95.3% under optimized condition.Graphical AbstractBulky phosphite with electron-withdrawing pyrrol groups dramatically improved the selective of linear product, and an excellent yield of 90.5% aldehydes with 95.3% regioselectivity of linear aldehyde was obtained in the Rh-catalyzed isomerization–hydroformylation of 2-butene in the presence of ligand 1.

Combination of RuCl3·xH2O with PEG – a simple and recyclable catalytic system for direct arylation of heteroarenes via C–H bond activation

A simple and recyclable catalytic system for direct arylation of heteroarenes via C–H bond activation was developed with a relatively inexpensive RuCl3·xH2O as a catalyst and PEG-400 as a green medium without any additive or ligand. This system not only showed excellent functional group compatibility, but also the ratio of mono- to diarylated product was easily regulated by varying the reaction conditions. Moreover, this transformation could proceed under air and be easily scaled up to gram-scale in a low catalyst loading of 0.3 mol%. Particularly, a good yield of 85% was obtained after this catalyst was recycled six times.

Direct C–H Functionalization of Pyridine via a Transient Activator Strategy: Synthesis of 2,6-Diarylpyridines

A Pd-catalyzed highly selective direct diarylation of pyridines has been developed using a transient activator strategy. Both (MeO)2SO2 and Cu2O are required for this transformation. The in situ generated N-methylpyridinium salt can be arylated at both 2- and 6-positions under the cooperative Pd/Cu catalysis. A subsequent N-demethylation then gives the 2,6-diarylpyridines. This protocol provides a novel synthetic route for the symmetric 2,6-diarylpyridines.

Rh(III)-Catalyzed [4 + 2] Self-Annulation of N-Vinylarylamides

An efficient rhodium(III)-catalyzed self-annulation of N-vinylarylamide has been developed. This reaction features a simple system and good reactivity with complete regioselectivity. The protocol provides easy access to an aminal incorporated dihydroisoquinolinone, which proved to be a versatile synthetic synthon. The kinetic isotope effect experiments showed that C-H activation is the rate-limiting step, and competition studies revealed the annulation exhibits a strong self-recognition mode. In addition, a seven-membered rhodacycle species was isolated and established as the key reaction intermediate.

Palladium-Catalyzed Domino Reaction for Stereoselective Synthesis of Multisubstituted Olefins: Construction of Blue Luminogens

The first Pd-catalyzed multicomponent reaction of aryl iodides, alkenyl bromides, and strained alkenes has been developed, which allowed us to synthesize a variety of multisubsituted olefins in yields of 45-96% with excellent stereoselectivity. The configuration of the product was controlled by the configuration of the alkenyl bromides. Moreover, this practical methodology employing readily available substrates was found to be tolerant to a wide range of functional groups. Fifty six examples of highly stereoselective tri- or tetrasubstituted olefins have been successfully synthesized via this methodology. Most of the synthesized tetrasubstituted olefins are good aggregation-induced emission (AIE) luminogens.

Synthesis and application of PNP pincer ligands in rhodium-catalyzed hydroformylation of cycloolefins

Two new phosphorus ligands (L1 and L2) were developed for rhodium-catalyzed hydroformylation of cycloolefins. L1 produced high conversion for cyclohexene (94.7%) and high dialdehyde selectivity for NBD (97.1%) and DCPD (98.4%). Analogue pincer ligands L3–L6 with different steric and electronic character were also investigated in these hydroformylations.