NHC-mediated photocatalytic deoxygenation of alcohols for the synthesis of internal alkynes via a Csp3-Csp coupling reaction.

NHC-mediated deoxygenation of alcohols under photocatalytic conditions is described. The process provides various alkyl radicals, which can react with 1-bromoalkyne via Csp3-Csp coupling to afford internal alkynes in moderate to good yields. The method offers a new and convenient approach to synthesize internal alkynes.

NHC-alcohol adduct-mediated photocatalytic deoxygenation for the synthesis of 6-phenanthridine derivatives.

NHC-alcohol adduct-mediated deoxygenation of alcohols under photocatalytic conditions is described. This process provides various alkyl radicals, which can react with 2-isocyanobiaryls to afford 6-substituted phenanthridine derivatives in moderate to good yields. This method offered the first example of directly using alcohols as radical sources for 6-phenanthridine synthesis.

Facile Synthesis of Tricyclic 1,2,4-Oxadiazolines-Fused Tetrahydro-Isoquinolines from Oxime Chlorides with 3,4-Dihydroisoquinoline Imines.

A mild and efficient strategy for the synthesis of tricyclic 1,2,4-oxadiazolines-fused tetrahydro-isoquinolines derivatives via [3 + 2] cycloaddition reaction is reported. The reactions provided the functionalized tricyclic 1,2,4-oxadiazolines in high yields (up to 96%). This protocol is simple and easy to handle. Moreover, a gram-scale experiment further highlights the synthetic utility. The chemical structure of the product was determined by X-ray single-crystal structure analysis. A possible mechanism for this transformation is proposed to explain the reaction process.

A copper iodide-catalyzed coupling reaction of benzofuran-3(2H)-ones with amines: an approach to α-ketoamides.

A CuI-catalyzed coupling reaction of benzofuran-3(2H)-ones with amines has been well established for the direct synthesis of α-ketoamides. This process involves C-O bond cleavage and C[double bond, length as m-dash]O/C-N bond formation. Mechanism studies indicated that this α-ketoamide formation reaction may involve a free radical process.

Rhodium-Catalyzed Annulation of α-Imino Carbenes with α,ß-Unsaturated Ketones: Construction of Multisubstituted 2,3-Dihydropyrrole/pyrrole Rings.

An efficient annulation of α-imino rhodium carbenes with α,ß-unsaturated ketones has been developed to generate multisubstituted 2,3-dihydropyrrole derivatives. Using the optimized catalyst, this approach is compatible with both cyclic and normal linear α,ß-unsaturated ketones. Further detosylation in the presence of base could produce multisubstituted pyrroles. The new method has the potential to enable the rapid construction of bioactive molecules containing pyrrole rings.

N-heterocyclic carbene-stabilized palladium complexes as organometallic catalysts for bioorthogonal cross-coupling reactions.

A small library of water-soluble N-heterocyclic carbene (NHC)-stabilized palladium complexes was prepared and applied for cross-couplings of biomolecules under mild conditions in water. Pd-NHC complexes bearing hydrophilic groups were demonstrated to be efficient catalysts for the Suzuki-Miyaura coupling of various unnatural amino acids and proteins bearing p-iodophenyl functional groups. We further utilized this catalytic system for the rapid bioorthogonal labeling of proteins on the surfaces of mammalian cells. These results demonstrated that NHC-stabilized metal complexes have potential utility in cellular systems.

KHCO3 Chemical-Activated Hydrothermal Porous Carbon Derived from Sugarcane bagasse for Supercapacitor Applications.

The reuse of waste biomass resources had become a hot topic in the sustainable development of human society. Biomass was an ideal precursor for preparing porous carbon. However, due to the complexity of biomass composition and microstructure, the quality reproducibility of biomass porous carbon was poor. Therefore, it was of great significance to develop a reliable method for preparing porous carbon from biomass. In this paper, the activated hydrothermal porous carbon was prepared by a combination of hydrothermal carbonization treatment and KHCO3 mild activation. The hydrothermal carbonization treatment could complete the morphology adjustment and iron doping of the carbon in one step, and the mild activation of KHCO3 could activate the porous carbon while maintaining the spherical morphology. Fe-modified porous carbon with carbon ball/nanosheet structure prepared from bagasse exhibited a high surface area (2169.8 m2/g), which facilitated ion/electrolyte diffusion and increased accessibility between surface area and electrolyte ions. Therefore, bagasse derived activated porous carbon had good specific capacitance (315.2 F/g at 1 A/g) and good cycle stability, with a capacitance loss of only 5.8 % after 5000 charge-discharge cycles, and the Na2SO4-based device showed the maximum energy density of 13.02 Wh/kg. This study showed that the combination of hydrothermal treatment and mild activation provided an effective way for the conversion of waste biomass into high-performance electrode materials.

One-pot synthesis of functionalized dihydropyridin-2-ones via carbene-catalyzed base-controlled [3+3] annulation reaction.

Herein, we have described a novel organocatalytic approach to access biologically important dihydropyridin-2-ones in a one-pot way with generally high yields (up to 99%) and excellent enantioselectivities (up to 99% ee). This reaction proceeded via a new dual activation mode, including in situ-generated α,ß-unsaturated acylazoliums and 4-dimethylaminopyridinium salts that underwent a Michael addition/1,4-H migration/lactamization sequence. The base-triggered 4-dimethylaminopyridinium ylide formation pathway over the competing substitution reaction pathway of vicinal haloamines is noteworthy.

1,3-Dipolar cycloaddition of isatin N,N'-cyclic azomethine imines with α,ß-unsaturated aldehydes catalyzed by DBU in water.

A simple and green procedure was established by [3 + 3] cycloaddition reaction of isatin derived cyclic imine 1,3-dipoles with α,ß-unsaturated aldehydes, giving the desired spiro heterocyclic oxindoles with aza-quaternary centers in good yields and diastereoselectivities. It should be noted that water can be employed as a suitable solvent for the improvement of diastereoselectivity.

Facile synthesis of pyrroloindoles via a rhodium(ii)-catalyzed annulation of 3-benzylidene-indolin-2-ones and α-imino carbenes.

The annulation of 3-benzylidene-indolin-2-ones with α-imino rhodium carbenes generated in situ from N-sulfonyl-1,2,3-triazoles is presented. Through the appropriate choice of catalyst, the reactions can be reasonably modulated, and consequently, a number of pyrroloindole derivatives were constructed in moderate to excellent yields.

Simple synthesis of neutral and cationic Cu-NHC complexes.

A direct and practical synthetic route to N-heterocyclic carbene copper complexes of [(NHC)CuX] (X = halide) and [(NHC)2Cu]PF6 types using commercially available copper powder is described. A number of copper-NHC complexes have been obtained in a range of yields from 26 to 99%. The reactions take place in air without removal of moisture and oxygen, and the excess of copper powder can be easily removed via simple filtration after completion. The direct reactions of imidazolium salts and copper powder can also be performed in aqueous media avoiding tedious purification processes. The procedure is also suitable for gram-scale preparation.

One-pot synthesis of 2,3-disubstituted dihydrobenzofurans and benzofurans via rhodium-catalyzed intramolecular C-H insertion reaction.

Intramolecular sp(3) C-H insertion reaction of α-imino rhodium carbene generated from N-sulfonyl-1,2,3-triazoles has been described. A number of 2,3-dihydrobenzofuran and benzofuran derivatives have been obtained in good to excellent yields.

Rhodium-catalyzed transannulation of N-sulfonyl-1,2,3-triazoles and epoxides: regioselective synthesis of substituted 3,4-dihydro-2H-1,4-oxazines.

Rhodium-catalyzed transannulation of 1,2,3-triazoles and ring-opening reactions of epoxides is described. A number of 3,4-dihydro-2H-1,4-oxazines are obtained in moderate yields probably involving generation of α-imino rhodium(II) carbene species.