Publications by authors named "Xueji Ma"

Article Synopsis
  • - A new organocatalytic method has been developed to efficiently produce dihydropyridin-2-ones in a single reaction step, achieving up to 99% yield and excellent enantioselectivity (up to 99% ee).
  • - The reaction utilizes a unique dual activation approach involving the formation of α,β-unsaturated acylazoliums and 4-dimethylaminopyridinium salts, which then undergo a sequence of reactions (Michael addition, 1,4-H migration, and lactamization).
  • - An important observation is that the reaction pathway leading to the formation of 4-dimethylaminopyridinium ylide is favored by a base, preventing a competing substitution reaction
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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.

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

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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.

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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.

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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.

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A simple and green procedure was established by [3 + 3] cycloaddition reaction of isatin derived cyclic imine 1,3-dipoles with α,β-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.

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An efficient annulation of α-imino rhodium carbenes with α,β-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,β-unsaturated ketones. Further detosylation in the presence of base could produce multisubstituted pyrroles.

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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.

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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.

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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.

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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.

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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.

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