Zinc salt-catalyzed reduction of α-aryl imino esters, diketones and phenylacetylenes with water as hydrogen source.

The zinc salt-catalyzed reduction of α-aryl imino esters, diketones and phenylacetylenes with water as hydrogen source and zinc as reductant was successfully conducted. The presented method provides a low-cost, environmentally friendly and practical preparation of α-aryl amino esters, α-hydroxyketones and phenylethylenes. By using D2O as deuterium source, the corresponding products were obtained in high efficiency with excellent deuterium incorporation rate, which gives a cheap and safe tool for access to valuable deuterium-labelled compounds.

Rhodium-catalyzed transfer hydrogenation of quinoxalines with water as a hydrogen source.

Rhodium-catalyzed transfer hydrogenation of quinoxalines with water as a hydrogen source was reported. The reaction allowed the simple preparation of tetrahydroquinoxalines under mild conditions. The deuterium-labelling experiment confirmed that water is the sole hydrogen source in the transfer hydrogenation reaction.

Enantioselective Total Synthesis of (+)-Nocardioazine B.

In this paper, we report an enantioselective total synthesis of (+)-nocardioazine B, a prenylated hexahydropyrrolo[2,3- b]indole (HPI) alkaloid with a central 2,5-diketopiperazine (DKP) ring. The key step in our synthetic route is a copper-catalyzed sequential arylation-alkylation of o-haloanilide derivatives. Based on this transformation, the construction of C3 all-carbon quaternary stereocenters presented in the HPI systems was achieved with high yields and excellent diastereoselectivity.

Palladium/zinc co-catalyzed asymmetric transfer hydrogenation of oxabenzonorbornadienes with alcohols as hydrogen sources.

Asymmetric transfer hydrogenation of oxabenzonorbornadienes was realized by using alcohols as hydrogen sources under a co-catalytic system of palladium and zinc. Both primary and secondary alcohols could serve as reductants and afforded enantiomerically enriched 1,2-dihydronaphth-1-ol products with high optical purities.

Rhodium-catalyzed asymmetric ring opening reaction of oxabenzonorbornadienes with amines using ZnI2 as the activator.

The complex of [Rh(COD)Cl]2 and (R,R)-BDPP was used as an effective catalyst for the asymmetric ring opening reaction of oxabenzonorbornadienes with various amines by employing ZnI2 as the activator. Under the optimized reaction conditions, high enantioselectivities with good yields could be obtained from a wide scope of oxabenzonorbornadienes and amines.

Palladium/Zinc Co-Catalyzed syn-Stereoselectively Asymmetric Ring-Opening Reaction of Oxabenzonorbornadienes with Phenols.

A new palladium/zinc co-catalyst system associated with chiral (R)-Difluorphos for asymmetric ring-opening reaction of oxabenzonorbornadienes with phenols is reported. This catalyst system allows the formation of cis-2-aryloxy-1,2-dihydronaphthalen-1-ol products in good yields (up to 95 % yield) with excellent enantioselectivities (up to 99 % ee). The cis-configuration of the product has been confirmed by X-ray crystal structure analysis. To the best of our knowledge, it represents the first example in ring-opening reactions of bicycloalkenes with heteronucleophiles in a syn-stereoselective manner.

Visible light-induced hydrogen atom transfer trifluoromethylthiolation of aldehydes with bismuth catalyst.

By using a combination of BiCl3 and TBACl as a ligand-to-metal charge transfer (LMCT) photocatalyst, hydrogen atom transfer trifluoromethylthiolation of aldehydes was achieved under visible light irradiation. The present method provides economical and operationally simple access to trifluoromethylthioesters using low toxicity and cost-effective bismuth catalysts under mild reaction conditions. Based on the radical trapping experiments, the direct conversion of aldehydes to acyl radicals via chlorine radicals as HAT reagents was proposed as the reaction mechanism.

A study on the substituent effects of norbornadiene derivatives in iridium-catalyzed asymmetric [2 + 2] cycloaddition reactions.

Employing a series of norbornadiene derivatives as substrates, the effects of various substituents on the Ir-catalyzed asymmetric [2 + 2] cycloaddition reactions with arylacetylenes were studied. It was found that the atom forming the short bridge chain had a great effect on the enantioselectivity of the reaction. Heteroatoms, such as oxygen and nitrogen, always resulted in excellent enantioselectivity. However, carbon atoms could decrease the enantioselective control ability of the catalyst over the reaction. The groups on the unreacted carbon-carbon double bond were found to have but a little effect on the reaction. Based on the results of the experiments, a mechanism was also hypothesized for the reaction.

Efficient synthesis of esermethole and its analogues.

In this work, a general and flexible synthetic route towards the synthesis of pyrroloindoline alkaloids was developed. This new strategy features with a palladium mediated sequential arylation-allylation of o-bromoanilides and leads to the construction of oxindoles bearing a full carbon quaternary center. The cheap triphenylphosphine was proved to be a highly effective ligand for this one pot transformation. On the basis of this new method, esermethole and its analogues were synthesized.

Photo-Promoted Decarboxylative Alkylation of α,ß-Unsaturated Carboxylic Acids with ICH2CN for the Synthesis of ß,γ-Unsaturated Nitriles.

An efficient, catalyst/photocatalyst-free, and cost-effective methodology for the decarboxylative alkylation of α,ß-unsaturated carboxylic acids to synthesize ß,γ-unsaturated nitriles has been developed. The reaction proceeded in an environmentally benign atmosphere of blue light-emitting diode irradiation with K2CO3 and water at room temperature. The methodology worked for a wide range of substrates (22 examples) with up to 83% yield. The protocol is also compatible for gram-scale synthesis.

Cobalt-catalyzed ring-opening addition of azabenzonorbornadienes via C(sp3)-H bond activation of 8-methylquinoline.

The first ring-opening addition of a benzylic C(sp3)-H bond to azabenzonorbornadienes is demonstrated. The reaction proceeded under the catalytic system of [Cp*CoI2(CO)], AgSbF6 and Fe(OAc)2 in PhOMe. The methodology showed a good substrate scope with up to 96% yield. The relative configuration of the product was determined as cis-configuration by X-ray crystallography.

Directing-Group-Controlled Ring-Opening Addition and Hydroarylation of Oxa/azabenzonorbornadienes with Arenes via C-H Activation.

An efficient method for the directing group controlled rhodium-catalyzed addition reaction of oxa/azabicylic alkenes with aromatic ketones and benzoic acids has been developed. The ketones and benzoic acids afforded different addition products when reacted with oxa/azabicyclic alkenes. The reaction between ketones and azabenzonorbornadienes furnished the ring-opening addition products. The reaction between benzoic acids and aza/oxabicyclic alkenes proceeded in the absence of silver salt, giving the 1:2 hydroarylation products in yields up to 96%.

Establishment of the key Technical Indicators of Positive Pressure Biological Protective Clothing.

OBJECTIVE: Trying to establish the key technical indicators related to positive pressure biological protective clothing (PPBPC), providing technical support for the establishment of PPBPC standards in the future. METHOD: We examined the protection standard systems established by the major standards organizations in China and other developed countries. We also analyzed the technical indicators of the gas-tight chemical protective clothing and ventilated protective clothing against particulate radioactive contamination which closely related to PPBPC. And tested the performance of a set of imported dual-purpose PPBPC to verify the fit of its technical indicators with the standards. We aimed to identify the status of China's standards in the area of personnel protection and put forward feasible suggestions for the production of PPBPC in China. RESULTS: Developed countries in Europe and North America have a complete system of standard protective clothing. China should also strengthen the construction of standard protective clothing, especially PPBPC. CONCLUSION: With the improvements in infectious disease prevention and control on a global scale, the demand for PPBPC continues to increase and consideration should be given to the establishment of standards for this.

Asymmetric Transfer Hydrogenation of Heterobicyclic Alkenes with Water as Hydrogen Source.

The asymmetric transfer hydrogenation of heterobicyclic alkenes was accomplished by using water as the sole hydrogen source. The transformation was co-catalyzed by Pd(OAc)2/Zn(OTf)2 dual catalyst with metallic zinc as reducing agent. Various azabenzonorbornadienes and oxabenzonorbornadienes were transformed to the corresponding chiral 1,2-dihydronaphthalenes by the asymmetric reductive ring-opening reactions with good to excellent enantioselectivities.

Cobalt catalyzed stereodivergent semi-hydrogenation of alkynes using H2O as the hydrogen source.

Cobalt-catalyzed stereodivergent semi-hydrogenation of internal alkynes to alkenes is developed. The reaction proceeded through transfer hydrogenation under mild conditions using a base metal CoI2 as the catalyst, and H2O/MeOH as the hydrogen source with Zn as the reductant. The E/Z-selectivity of the product could be switched by changing the solvent and by inclusion/exclusion of a bidentate phosphine ligand (dppe). This method provides a simple and cost effective pathway for the synthesis of 1,2-dideuterioalkenes.

Blue Light Induced Difluoroalkylation of Alkynes and Alkenes.

The difluoroalkylation of alkynes and alkenes by direct photoexcitation of ethyl difluoroiodoacetate is described. Under catalyst- and oxidant-free conditions, iododifluoroalkylation and hydrodifluoroalkylation products were generated from alkynes, and difluoroalkylation products were prepared from alkenes. This methodology provides a streamlined access to difluoroalkylated organic compounds starting from simple alkynes or alkenes.

The Differential Characteristics Between Severe Fever With Thrombocytopenia Syndrome and Hemorrhagic Fever With Renal Syndrome in the Endemic Regions.

An effective differentiation between severe fever with thrombocytopenia syndrome and hemorrhagic fever with renal syndrome was attained by a model considering patients' age, mouse/tick contact, presence of blush, low back pain, diarrhea, enlarged lymph nodes, and white blood cell count.

Rhodium-Catalyzed Asymmetric Arylative Ring-Opening Reactions of Heterobicyclic Alkenes with Anilines.

Asymmetric arylative ring-opening reactions of heterobicyclic alkenes with anilines have been reported for the first time. A wide range of heterobicyclic alkenes, including azabenzonorbornadienes and oxabenzonorbornadienes, were well tolerated in the reaction with various anilines, and they generally delivered the corresponding chiral aryltetralin derivatives in good to excellent enantioselectivities. The reaction is speculated to proceed through the Friedel-Crafts reaction pathway.

Nickel-Catalyzed Asymmetric [2+2] Cycloaddition Reaction of Hetero-Bicyclic Alkenes with Internal Alkynes.

Enantioselective [2+2] cycloaddition reaction of azabenzonorbornadienes and oxabenzonorbornadienes with internal alkynes has been enabled by a catalyst system comprising Ni(COD)2 and (R)-SIPHOS-Ph-Mor. This transformation represents the first asymmetric [2+2] cycloaddition reaction of azabenzonorbornadienes with internal alkynes, providing a straightforward method to prepare four-membered carbocycles.

Rhodium-Catalyzed Generation of Anhydrous Hydrogen Iodide: An Effective Method for the Preparation of Iodoalkanes.

The preparation of anhydrous hydrogen iodide directly from molecular hydrogen and iodine using a rhodium catalyst is reported for the first time. The anhydrous hydrogen iodide generated was proven to be highly active in the transformations of alkenes, phenyl aldehydes, alcohols, and cyclic ethers to the corresponding iodoalkanes. Therefore, the present methodology not only has provided convenient access to anhydrous hydrogen iodide but also offers a practical preparation method for various iodoalkanes in excellent atom economy.