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Glycans have diverse physiological functions, ranging from energy storage and structural integrity to cell signalling and the regulation of intracellular processes1. Although biomass-derived carbohydrates (such as d-glucose, d-xylose and d-galactose) are extracted on commercial scales, and serve as renewable chemical feedstocks and building blocks2,3, there are hundreds of distinct monosaccharides that typically cannot be isolated from their natural sources and must instead be prepared through multistep chemical or enzymatic syntheses4,5. These ‘rare’ sugars feature prominently in bioactive natural products and pharmaceuticals, including antiviral, antibacterial, anticancer and cardiac drugs6,7. Here we report the preparation of rare sugar isomers directly from biomass carbohydrates through site-selective epimerization reactions. Mechanistic studies establish that these reactions proceed under kinetic control, through sequential steps of hydrogen-atom abstraction and hydrogen-atom donation mediated by two distinct catalysts. This synthetic strategy provides concise and potentially extensive access to this valuable class of natural compounds. Various rare sugars that cannot be isolated from natural sources are synthesized using light-driven epimerization, a process which may find application in other synthetic scenarios.

Being a suitable way for achieving the maximum efficiency of atoms, the atomically dispersed metals are playing an ever-increasingly important role in bridging heterogeneous and homogeneous catalysis. It is extremely challenging for dispersing metals in atomic-scales as the applicable high-loading catalysts for industry. The reducible and defective supports or metal surfaces are commonly chosen for anchoring the metals. We here report that atomically-dispersed but high-loading (15 wt%) metals were achieved by covalent-bonding to irreducible SiO 2 (though silanol groups) which is realized by a simple urea hydrolysis assistant hydrothermal-deposition method. The Cu O Si bonding tailors the structural and electronic states of catalyst by maximum of atom efficiency and tuning electronic effects. The intrinsic performance of C O hydrogenation was thus boosted by one- to two- orders-of-magnitude in comparison with impregnated and precipitated catalysts. The choices of metals include Cu, Zn, Ni, Co and Mn, showing potentials for a category of applied materials.

A series of novel heterogeneous gold(I) catalysts were synthesized by immobilizing gold(I) complexes on ordered mesoporous polymer FDU-15 and characterized by XRD, N2 adsorption–desorption, FT-IR, TEM, EDS, etc. The catalytic activities of these catalysts were evaluated by the amination reactions of allylic alcohols. Among the catalysts investigated, FDU-(p-CF3Ph)2PAuCl (3d) was identified as the most efficient catalyst. Compared to the homogeneous catalyst, the enhanced catalytic activity of the heterogeneous gold(I) catalyst is closely related to the mesoporous structure of FDU-15. The catalytic system was suitable for a broad range of substrates and can be easily recovered and recycled at least twelve times without significant loss of catalytic activity. In addition, the catalytic performance of 3d was further examined for intramolecular cyclization for the synthesis of heterocyclic compounds.

Liquid phase hydrogenation of nitriles is an important method for the production of amines, which find a variety of applications as intermediates in chemical and pharmaceutical industry. In the present work, a highly efficient Pd@mpg-C3N4 catalytic system has been developed for chemoselective reduction of nitriles providing good to excellent conversion with remarkable chemoselectivity (up to 99%) without additives. Compared with homogeneous catalyst systems, the developed protocol is more advantageous due to the use of ambient hydrogen, solvent free and effective catalyst recyclability.

We report that when Ir and La halides are deposited on carbon, exposure to CO spontaneously generates a discrete molecular heterobimetallic structure, containing an Ir-La covalent bond that acts as a highly active, selective, and stable heterogeneous catalyst for the carbonylation of methanol to produce acetic acid. This catalyst exhibits a very high productivity of ∼1.5 mol acetyl/mol Ir·s with >99% selectivity to acetyl (acetic acid and methyl acetate) without detectable loss in activity or selectivity for more than 1 month of continuous operation. The enhanced activity can be mechanistically rationalized by the presence of La within the ligand sphere of the discrete molecular Ir-La heterobimetallic structure, which acts as a Lewis acid to accelerate the normally rate-limiting CO insertion in Ir-catalyzed carbonylation. Similar approaches may provide opportunities for attaining molecular (single site) behavior similar to homogeneous catalysis on heterogeneous surfaces for other industrial applications.

A general and mild hydrosilylation of thioalkynes is described. With the cationic catalyst [Cp*Ru(MeCN)3 ](+) and the bulky silane (TMSO)3 SiH, a range of thioalkynes underwent smooth hydrosilylation at room temperature with excellent α regioselectivity and syn stereoselectivity. DFT calculations provided important insight into the mechanism, particularly the unusual syn selectivity with the [Cp*Ru(MeCN)3 ](+) catalyst. The sulfenyl group in the substrates was found to provide important chelation stabilization to direct the reaction through a new mechanistic pathway.

An efficient catalytic system for Suzuki–Miyaura coupling reactions in neat water has been developed by using a water-soluble Pd(l-proline)2 catalyst. Under the optimized conditions, various biaryl compounds were obtained in good to excellent yields and a wide range of functional groups on the tested substrates were well tolerated. The catalytic system could be reused at least six times with no significant loss in its activity. Copyright © 2014 John Wiley & Sons, Ltd.

The insoluble Wilkinson catalyst RhCl[P(m-C6H4SO3)Na)3]3 changes from inert to very active by supported on mesoporous material SBA-15, and the catalyst is stable, easy to separate from products, clean, and can be reused directly. This catalyst combines the advantages of homogeneous catalysts and heterogeneous catalysts very well.

Commercial MoS2 was found to be a highly selective catalyst for the reduction of nitrobenzenes to the corresponding anilines with hydrazine under mild conditions. MoS2 is not only much cheaper, but also more selective than noble metal catalysts for the reduction of functional nitrobenzenes to the corresponding anilines. Nitrobenzenes with halides (F, Cl, Br and I) were reduced selectively, and the corresponding anilines were obtained in excellent yields, and no dehalogenation was detected. Functional groups such as NH2, OH, alkene groups were tolerated during the reduction of the nitro compounds. The reduction of p-chloronitrobenzene was studied over MoS2 and Pd/C respectively with hydrazine. The yield of p-chloroaniline was much higher with MoS2 than that with Pd/C at full conversion.

The activity of eleven separated iron complexes and nine in situ-generated iron complexes towards catalytic water oxidation have been examined in aqueous solutions with Ce(NH4)2(NO3)6 as the oxidant. Two iron complexes bearing tridentate and tetradentate macrocyclic ligands were found to be novel water oxidation catalysts. The one with tetradentate ligand exhibited a promising activity with a turnover number of 65 for oxygen evolution.

The imidazolium ionic liquids were used as solvents for the oxidation of 2,3,6-trimethylphenol (TMP) to trimethyl-1,4-benzoquinone (TMBQ), eliminating the need for volatile and flammable organic solvents. Compared with those in traditional organic solvents, the conversion and selectivity obtained in 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF 4 ) were significantly increased. It provides a good alternative way for the industrial synthesis of TMBQ.