Ferric nitrate-promoted oxidative esterification of toluene with N-hydroxyphthalimide: Synthesis of N-hydroxyimide esters

A ferric nitrate-promoted cross-dehydrogenative coupling reaction of N-hydroxyphthalimide (NHPI) with toluene derivatives is reported. The reaction proceeded smoothly using molecular oxygen as an oxidant, providing an efficient method for the synthesis of N-hydroxyimide esters. Furthermore, a plausible mechanism was proposed.     

Chemoselective aerobic oxidation of 2-amino-N-benzylanilines into N-(2-aminophenyl)imines via a nitroxide-free copper catalysis

Chemoselective oxidative synthesis of N-(2-aminophenyl)imines from 2-amino-N-benzylanilines was accomplished through combined use of O₂(air) and copper salt. This transformation was performed at room temperature, and the mild oxidation was efficient and chemoselective without using nitroxyl radicals and ligands.     

Metal-free synthesis of benzimidazo[1,2-c]quinazolin-6-ones with indole and benzenediamine oxidized by I2/TBHP

A variety of benzimidazo[1,2-c]quinazolin-6-ones derivatives can be accessed in moderate to good yields under simple and metal-free reaction conditions using indoles and o-benzenediamines oxidized by iodine and TBHP. This procedure works in reasonable yields for different indoles as well as o-benzenediamines thus may provide a good synthesis of quinazolinones. A TBHP oxidized ring expansion reaction mechanism that explains the synthesis of benzimidazo[1,2-c]quinazolin-6-ones were reported.     

Two new dimmeric xanthanolides isolated from Xanthium mogolium Kitag plant

Two xanthanolide-type dimmers, namely Mogolide D (4) and Mogolide E (5) are isolated from the aerial parts of Xanthium mogolium Kitag plant collected from Heilongjiang province, China. The dimmers’ relative structures are elucidated on the basis of HRESIMS, IR spectrum and NMR spectroscopy. The absolute configurations of them are assigned with ECD spectra. The biosynthetic pathway of the two dimmers is also proposed. Besides, Mogolide D (4) and Mogolide E (5) are tested against MDA-MB-231 breast cancer cell line with IC₅₀ 8.46 μM and 19.20 μM, respectively.     

Unexpected intramolecular nucleophilic cyclization of ureidoacetamide: A novel route towards the synthesis of 2,4,5-trisubsituted oxazoles

A variety of N, 2-diaryl-2-ureidoacetamide prepared from the condensation of N-aryl-α-aminoamide with potassium cyanate (KOCN) undergo efficient Hendrickson’s reagent-mediated nucleophilic cyclization to afford 2,5-diamine-4-aryloxazoles. The two-step synthesis provides seven target products in yields of 61–78% under mild conditions. This reaction involves an unusual pathway in which the electrophilic amide carbonyl carbon is activated by Hendrickson’s reagent and attacked by a nucleophilic ureido oxygen in a 5-exo-trig O-cycloisomerization.     

Copper-catalyzed aryldifluoromethylenation of N-arylacrylamides to synthesis of the diheterocyclic compounds linked by gem-difluoromethylene moiety

An efficient method of copper-catalyzed aryldifluoromethylenation of N-arylacrylamides is described to step-economic synthesis of the various biologically important biheterocyclic compounds linked by gem-difluoromethylene moiety through addition of benzo-1,3-azolic (oxa- or thia-)difluoromethyl radicals generated in situ to terminal of C–C double bond of N-arylacrylamides then cyclization cascade. This protocol has demonstrated to have broad substrate scope and excellent functional-group tolerance under mild reaction conditions.     

Water-controlled nitro-oximation of alkenes under catalyst-free conditions

A convenient and precise nitration and oximation of alkenes with tert-butyl nitrite has been reported, yielding α-nitro ketoximes in satisfactory yields with broad substrate generality and excellent stereoselectivity under mild conditions. Experiments indicate that tert-butyl nitrite serves as both NO and NO₂ sources and water plays a key role in this difunctionalization reaction.     

A visible-light-promoted cross-dehydrogenative-coupling reaction of N-arylglycine esters with imidazo[1,2-a]pyridines

A mild and convenient visible-light-promoted cross-dehydrogenative-coupling reaction between N-arylglycine esters and imidazo[1,2-a]pyridines for the construction of CC bond was developed. A range of N-arylglycine esters and imidazo[1,2-a]pyridines were able to undergo the CDC reaction readily to afford α-heteroaryl substituted α-amino acid derivatives in good to excellent yields. A tentative mechanism for the photoredox reaction was also proposed. Importantly, the use of copper(II) salt as the sole catalyst in this visible-light-promoted transformation makes this reaction sustainable and practical.     

Dehydrogenative etherification homocoupling of heterocyclic N-oxides

A novel approach was developed for the dehydrogenative etherification homocoupling of heterocyclic N-oxides in the presence of silver oxide and PyBroP. Various substrates were well tolerated and the desired products were obtained in moderate to good yields. Generally, this reaction features excellent functional group compatibility, broad substrate scope and good regioselectivity.     

Copper-catalyzed cross-coupling of chloramine salts and arylboronic acids in water: A green and practical route to N-arylsulfonamides

A green and practical method for the synthesis of N-arylsulfonamides from chloramine salts and arylboronic acids is herein developed. The reaction proceeds readily in the presence of 5?mol% of CuI and 2.5?equiv. K₂CO₃ in water at room temperature, generating a variety of N-arylsulfonamides in moderate to good yields with good functional group tolerance.     

Two novel C18-diterpenoid alkaloids,sinomontadine with an unprecedented seven-membered ring A and chloride-containing sinomontanine N from Aconitum sinomontanum

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Synthesis of 3-aminoindan-1-one derivatives from 2-acetylbenzaldehydes and secondary amines by Mannich annulation

An acid-promoted 2-component Mannich annulation reaction of readily available acetylbenzaldehydes and secondary amines has been reported. The approach provides a simple and efficient method under mild conditions to synthesize 3-aminoindan-1-one derivatives in moderate to good yields.     

Organocatalytic stereoselective conjugate addition of 3-substituted oxindoles with in situ generated ortho-quinone methides

A novel method for the stereoselective conjugate addition of 3-substituted oxindoles to in situ generated o-QMs was described. This process was catalyzed efficiently by a cinchonidine-derived squaramide catalyst in oil-water phase, furnishing the corresponding 3,3-disubsituted oxindole derivatives in moderate to high yields (up to 98%) with high stereoselectivities (up to 95%?ee, 15.4:1?dr). The utility of this reaction was also investigated by the gram-scale synthesis and derivatization of one of the products.     

Geometry,stability and aromaticity of β-diketiminate-coordinated alkaline-earth compounds

Alkaline-earth (Ae) metals have attracted a wealth of interdependent research from synthetic chemists. In Ae-catalyzed organometallic reactions, β-diketiminate is a typical ligand used to stabilize Ae catalysts by forming six-membered rings comprising Ae metals. Herein, studies focusing on the configuration of β-diketiminate-coordinated Ae compounds observed that the CC and CN bonds are homogeneous and unchanged. Furthermore, energetic studies observed that the formation of the Ae-incorporated six-membered rings results in enhanced stability of >20 kcal/mol. The nucleus-independent chemical shifts, anisotropy of the induced current density, and molecular orbital analyses demonstrated the non-aromaticity of the β-diketiminate-coordinated Ae compounds. The improved stability of these compounds can be explained by the delocalization of the π electrons derived from the β-diketiminate moiety.     

A consecutive one-pot two-step approach to novel trifluoromethyl-substituted bis(indolyl)methane derivatives promoted by Sc(OTf)3 and p-TSA

A one-pot two-step reaction of 3-(trifluoroacetyl)coumarin and indole afforded trifluoromethyl-substituted bis(indolyl)methane compounds containing coumarin skeleton. The atomic economic and simply manipulative reaction involved premier treatment of reaction mixtures with Sc(OTf)₃, followed by p-TSA in one-pot process. The reaction proceeded to give the title compounds in high yields (up to 95% yield).     

Transition-metal-free,visible-light-mediated regioselective C–H trifluoromethylation of imidazo[1,2-a]pyridines

A transition-metal-free, visible-light-induced trifluoromethylation of imidazo[1,2-a]pyridines has been developed at mild conditions by employing cheap and commercially available anthraquinone-2-carboxylic acid (AQN-2-CO₂H) as the photo-organocatalyst, and Langlois reagent as the trifluoromethylating reagent. A series of 3-(trifluoromethyl)imidazo[1,2-a]pyridine derivatives with broad functionalities could be conveniently and efficiently obtained by direct regioselective functionalization.     

Palladium-catalyzed arylation/cyclization/desulfonation cascades toward 4-aryl quinolin-2(1H)-ones with diaryliodonium salts

Palladium-catalyzed cascades of arylation/cyclization/desulfonation of ortho-aminocinnamate esters by using diaryliodonium salts afforded a wide range of 4-aryl quinolin-2(1H)-ones. As such, the desired 4-aryl quinolin-2(1H)-ones with potential biological activity has been synthesized in the yields of 34–96%.     

Nd(OTf)3-catalyzed intramolecular-intermolecular cascade cyclization reaction: An access to phenanthro[9,10-b]furan derivatives

An intramolecular-intermolecular cascade cyclization reaction via multi metal-carbene intermediates has been developed. This reaction uses catalytic amount of Nd(OTf)₃, which actives both alkyne and aldehyde moieties. This protocol provides a novel strategy for the synthesis of phenanthro[9,10-b]furans.     

Green synthesis and application of nanoscale zero-valent iron/rectorite composite material for P-chlorophenol degradation via heterogeneous Fenton reaction

A zero-valent iron/rectorite nanocomposite (NZVI/rectorite) was developed as a heterogeneous H₂O₂ catalyst for P-chlorophenol degradation. The physicochemical properties of NZVI/rectorite were characterized by various techniques including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller analysis. Results showed that NZVI sphere nanoparticles were successfully loaded on the rectorite surface with less aggregation and good dispersion. Moreover, compared with acid-leached rectorite (30.91 m²/g), the NZVI/rectorite appeared to have larger surface area (50.75 m²/g). In addition, the effects of pH, reaction time, initial P-chlorophenol concentration, catalyst amount, and H₂O₂ dosage on the P-chlorophenol degradation were systematically investigated. Results showed that NZVI/rectorite presents better properties for the degradation and mineralization of P-chlorophenol compared with pristine NZVI due to the large surface area, low aggregation, and good dispersion of the former. The degradation mechanisms of P-chlorophenol by NZVI/rectorite were adsorption and reduction coupled with a Fenton-like reaction. Four successive runs of the stability and regeneration study also showed that the NZVI/rectorite were unchanged even after 100% of P-chlorophenol degradation ratio. This study has extended the application of NZVI/rectorite as environment function material for the removal of P-chlorophenol from the environment.