Practical chemoselective aromatic substitution: the synthesis of N-(4-halo-2-nitrophenyl)benzenesulfonamide through the efficient nitration and halogenation of N-phenylbenzenesulfonamide.

A novel route involving the metal-promoted tandem nitration and halogenation of N-phenylbenzenesulfonamide to synthesize N-(4-halo-2-nitrophenyl)benzenesulfonamide derivatives has been developed. The method shows highly practical chemoselective and functional group compatibility. In addition, it employs insensitive and inexpensive Cu(NO3)2·3H2O, Fe(NO3)3·9H2O, and NH4NO3 as the nitration reagents, and it provides a direct approach for the preparation of 4-halo-2-nitroaniline, which is a crucial intermediate for the synthesis of benzimidazoles and quinoxaline derivatives.

Nickel-Catalyzed Enantioselective Arylative Activation of Aromatic C-O Bond.

The pioneering nickel-catalyzed cross-coupling of C-O electrophiles was unlocked by Wenkert in the 1970s; however, the transition-metal-catalyzed asymmetric activation of aromatic C-O bonds has never been reported. Herein the first enantioselective activation of an aromatic C-O bond is demonstrated via the catalytic arylative ring-opening cross-coupling of diarylfurans. This transformation is facilitated via nickel catalysis in the presence of chiral N-heterocyclic carbene ligands, and chiral 2-aryl-2'-hydroxy-1,1'-binaphthyl (ArOBIN) skeletons are delivered axially in high yields with high ee. Moreover, this versatile skeleton can be transformed into various synthetic useful intermediates, chiral catalysts, and ligands by using the CH- and OH-based modifiable sites. This chemistry features mild conditions and good atom economy.

Asymmetric Michael addition reactions of nitroalkanes to 2-furanones catalyzed by bifunctional thiourea catalysts.

The first bifunctional thiourea catalyzed asymmetric Michael addition reactions of nitroalkanes to 2-furanones are described. The highly functionalized γ-lactones with two or three consecutive stereogenic carbons were obtained in high yields (up to 99%), high diastereoselectivities (up to >20 : 1 dr) and enantioselectivities (up to >99% ee).

A novel chitosan/cellulose phosphonate composite hydrogel for ultrafast and efficient removal of Pb(II) and Cu(II) from wastewater.

Developing green and high-performance adsorbents to separate heavy metals from wastewater is a challenging task. Biomass hydrogel has the advantages of low cost, renewability, and biodegradability, but it has the problem of low adsorption efficiency. Herein, a novel chitosan/cellulose phosphonate composite hydrogel(CS/MCCP) is fabricated by two steps of reactions including the Phosphorylation reaction and the Mannich reaction. As an excellent chelating group, the phosphonate group greatly enhances the adsorption efficiency of the biomass hydrogel. The CS/MCCP shows ultrafast adsorption rate and excellent adsorption capacity for Pb(II) and Cu(II). The saturated adsorption capacity of Pb(II) and Cu(II) is 211.42 and 74.29 mg·g-1, respectively. The adsorption equilibration time is only 10 min. The adsorption performance of the CS/MCCP is superior to that of the reported cellulose/chitosan hydrogels. Besides, an in-depth analysis of the adsorption mechanism is conducted using X-ray photoelectron spectroscopy(XPS) combined with Density Functional Theory(DFT) calculation. The results reveal that the adsorption mechanism is electrostatic attraction and surface complexation, and there is a synergistic coordination between the phosphonate groups and the amino groups.

Cellulose phosphonate/polyethyleneimine nano-porous composite remove toxic Pb(II) and Cu(II) from water in a short time.

Current cellulose-based adsorbents suffer from the drawbacks of low adsorption capacity or slow adsorption rate for heavy metal ions. It is imperative to prepare new cellulose-based materials to improve the adsorption ability. In this work, we aim to introduce phosphonate groups to improve the adsorption ability of cellulose and select polyethyleneimine (PEI) for synergistic adsorption. A novel cellulose phosphonate/polyethyleneimine composite (MCCP-PEI) is prepared via the Mannich reaction. The structure and composition of MCCP-PEI are characterized by various advanced microscopy and spectroscopy techniques, and the results show that MCCP-PEI possesses abundant nano-porous structure, strong chelating sites, and excellent hydrophilicity. Besides, the adsorption behavior of MCCP-PEI for heavy metals has been systematically investigated. The results show that the adsorbent can quickly remove toxic Cu(II) and Pb(II) from water within 15 min and 20 min, respectively. The saturated adsorption capacity for Cu(II) and Pb(II) is 250.0 and 534.7 mg·g-1, respectively. X-ray photoelectron spectroscopy analysis combined with Density Functional Theory calculations reveal that the adsorption mechanism is chemical complexation and electrostatic attraction, and the phosphonate group plays a key role in the adsorption process.

Iron-catalysed reductive coupling for the synthesis of polyfluorinated compounds.

Herein we reported the use of Earth-abundant iron as the catalytic metal in the presence of Mn to induce difluorobromoacetates to form carbon radicals, which reacted with trifluoromethyl olefins followed by ß-F elimination to generate the corresponding gem-difluoroolefins. The cross-electrophile coupling displayed excellent functional group tolerance and broad substrate scope under mild reductive conditions, affording a large number of polyfluorinated compounds, which could be further transformed to other valuable molecules.

WITHDRAWN: Discovery of 5-benzylidene(thio) barbiturates as a new class of mushroom tyrosinase inhibitors.

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