Current Chinese Chemistry - Current Issue

Calcium carbide (CaC2) as an important raw material has been widely used in inorganic chemistry, nanomaterials, supramolecular and other fields. In recent years, calcium carbide has been applied as an inexpensive, safe, green, and sustainable acetylene source in organic synthesis. This mini-review summarizes the latest progress of calcium carbide as a surrogate of acetylene gas in organic reactions for the construction of C-C, C-N, C-S, and C-O bonds.

Background: The treatment of cancer requires scientific advancement. ATP-competitive mTOR inhibitors have been studied as potential antitumor agents.

Objective: A series of substituted benzimidazole compounds were designed, synthesized and characterized via introducing 2-chloroquinolin into 2^nd position and most title compounds exhibited enhanced anticancer activities.

Methods: To study the anticancer mechanism, VIa-VIh was successfully docked by iGEMDOCK 2.0 which gives good affinity towards m-TOR/PI3K dual inhibitors. The anti-proliferative activities of these compounds were evaluated on MCF-7 and A549 cell line for Breast and lung cancer, respectively.

Results: 2-(2-chloroquinolin-3-yl)-1H-benzoimidazol-1-yl)(phenyl)methanone (VIa) exhibited significant anti-proliferative activity, especially against breast cancer (IC50 197 µM) for MCF7 cell line and (2-(2-chloroquinolin-3-yl)-1H-benzo[d]imidazol-1-yl)(4-nitrophenyl)methanone (VIc) was significantly active against lung cancer (IC50 89 µM) for A579 cell line.

Conclusion: VIa gives more activity on breast cancer and it gives IC50 197 µM for MCF7 cell line and (2-(2-chloroquinolin-3-yl)-1H-benzo[d]imidazol-1-yl) (4-nitrophenyl) methanone (VIc) lung cancer IC50 89 µM for A579 cell line.

Introduction: Unexpected series of N,N-disubstituted formamidines were obtained upon the reaction of 2-amino-3-cyano-4.6-diarylpyridines with triflouroroacetic anhydride (TFAA) in dimethyl formamide (DMF).

Methods: The syn/anti ratio of N,N-disubstituted formamidines was calculated by applying the 1H-NMR additivy increment rule. The mechanism of formamidine formation is suggested using the experimental results, 1H NMR and 13C NMR spectroscopy and successfully computed with DFT calculations using the B3LYP functional and 6-311G (p,d) basis set.

Results: The reaction mechanism classified as unexpected nucleophilic attack reaction of the solvent (DMF) on the carbonyl group leaving a positively charged intermediate which was attacked with nitrogen atom of the amine form N,N-disubstituted formamidines. Bond lengths and Mulliken atomic charges were calculated to support the reliability of the predicted reaction mechanism. The activation energy of each species appears in the reaction pathway was calculated.

Conclusion: HOMO-LUMO analysis showed that the reaction pathway is preferred to proceed through the suggested mechanism. It is clear that DMF is not the appropriate solvent in the case of preparation of triflouroacetamide.

Background: Biginelli reaction is the most well-known and widely studied, multi-component reaction used for the direct synthesis of many biologically active 3,4-dihydropyrimidin-2(1H)-ones and their derivatives by reacting a β-keto ester/1,3-dicarbonyl compound, an aldehyde, and urea. It is catalyzed by different Bronsted and Lewis acids.

Methods: The catalytic effect of different metal chlorides, such as sodium, potassium, magnesium, stannous, ferric, manganese, cupric, nickel, cobalt, and zinc, in absence and presence of acetic acid were studied.

Results: The zinc, ferric, cupric, and cobalt chlorides were found to be more effective catalysts for Biginelli reaction at room temperature. The yield of the reaction increased with temperature for all catalytic systems. Acetophenone, cyclohexanone, acetyl acetone, and different β-ketoesters formed tetrahedropyrimidine in moderate to good yield, by using zinc chloride catalyst at room temperature in acetic acid. The efficiency of the catalyst was studied by treating different substituted aldehydes with 1,3-dicarbonyl compounds and urea at room temperature.

Conclusion: The zinc chloride in acetic acid found to be an effective greener catalyst system for Biginelli reaction.

Background: Porous Au nanomaterials show great potential in the fields of biomedicine, drug delivery, and catalysis for the merits of low density, large void space, and large specific surface area. The preparation of porous Au nanomaterials is usually carried out by using a hard-templating method, which is cumbersome.

Methods: Dandelion-like porous Au nanoparticles were synthesized through a soft-templating method in our work. The synthesized porous Au nanoparticles were characterized via transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and cyclic voltammetry (CV). The reduction of nitrophenol was carried out to evaluate the catalytic behavior of porous Au nanoparticles.

Results: Porous Au nanoparticles prepared were in uniform size (47.9±6.4 nm) and the morphology could be regulated by adjusting the molar ratio of reactants. The apparent rate constant (kapp) value of reducing nitrophenol catalyzed by porous Au nanoparticles was higher than Au nanospheres and nanobranches in a similar size. It could be attributed to a large amount of active sites and high proportion of high-order crystal faces proved by CV and XRD.

Conclusion: We developed a facile and reproducible method for synthesizing porous Au nanoparticles. The morphology of porous Au nanoparticles can be ajusted by changing the molar ratio of reactants. Porous Au nanoparticles that we prepared behaved better in catalysis compared with Au nanospheres and Au nanobranches.

Background: A density functional theory (DFT) study of some selected eco-friendly chitosan derivatives was performed, recently used as corrosion inhibitors for steel in 0.1M and 0.5M HCl. Correlation between observed and predicted inhibition efficiencies is based on QSAR by some statistical calculations.

Methods: We extracted the optimum molecular descriptors for the chitosan derivatives group under study and it was found that these descriptors have a proper effect on increasing the inhibition efficiency that was proved by applying the theoretical calculations (non-linear regression) on two models of chitosan derivatives (ChI and ChII). The quantum chemical descriptors most relevant to the corrosion inhibitors potential effect have been calculated in the aqueous phase. They include: EHOMO, ELUMO, dipole moment (D), molecular area (MA), molecular volume (MV), the charge on common oxygen (O Charge), the charge on common nitrogen (N Charge), nuclear repulsion energy (NRE), final single point energy (E) and total positive charge (TPC).

Results: The optimum parameters resulted using multiple linear regression are EHOMO, CCO, CCN, and D. Using these optimum parameters, the models designed show good results in their inhibition effect on steel at the same environment of the chitosan derivatives group under study.

Conclusion: Experimental explanation showed good results from modelling prediction, where the corrosion rate decreases markedly with increasing the concentration of the designed inhibitors till the optimum concentration where the rate becomes constant. SEM on the optimum inhibitor concentration proved the high inhibition efficiency obtained.

Objective: In the present research article, we synthesized novel pregnane derivatives from 16-dehydropregnenolone acetate (1) obtained by the degradation of naturally occurring plant product-diosgenin. The oxime esters, 3β-acetoxy-pregn-5,16-diene, 20-one O-(2-(6-methoxynaphthalene-2yl) propionyl) oxime (5) and 3β-hydroxy-pregn-5, 16-diene, 20-one O-(2-(4-isobutyl phenyl) propionyl) oxime (6) have been synthesized by reaction of 3β-acetoxy-5,16-pregnadien-20-oxime (3) with NSAIDs Ibuprofen and naproxen, respectively.

Methods: The epoxide derivative 3β-hydroxy-16α, 17α-epoxypregn-5-ene-20-one (4) was opened by BF3.Et2O and yielding product 3,16-di-hydroxy pregn-5-ene-20-one (7) and 3,16,17-tri-hydroxy pregn-5-ene-20-one (8), both the synthesized compounds underwent esterification with Ibuprofen affording 3,16-di-(2-(4-isobutyl phenyl) propionoxy) pregn-5-ene-20-one (9) and 3,16-di-(2-(4-isobutyl phenyl) propionoxy) 17-hydroxy pregn-5-ene-20-one (10), respectively.

Results: A one novel pregnane glycoside 3β-[2¢,3¢,4¢,6¢-tetra-O-acetyl-β-D-glucopy-ranosyl]-Oxy-20β-hydroxy-16α-methoxy-pregn-5-ene (15) has also been synthesized from 3β, 20β-dihydroxy-16α-methoxy-pregn-5-ene (12).

Conclusion: After the synthesis, all the compounds have been characterized by modern spectroscopic techniques.

To separate and optimize the bioactive fraction of Hemidesmus indicus as an antimicrobial lead using in silico QSAR model development.

Hemidesmus indicus was extracted by soxhalation. The crude extract is fractionated using solvents of different polarity and assessed for its antimicrobial activity. The bioactive fraction is further analysed by GC-MS to analyse the constituents. These moieties were studied for their molecular interaction using CoMFA based QSAR model development.

The bioactive fraction found to have antibacterial and antifungal activities. GC-MS revealed the presence of eicosane, pthalic acid, oleanen 3 -yl acetate and substituted alkanes. Force field analysis followed by simulation revealed that pthalic acid was found to have interaction with the receptors.

Thus the integration of activity guided fractionation with cheminformatics may reveal the putative leads in drug design. Pthalic acid analogues can thus be optimized further by subjecting to preclinical drug studies.