Journal of Chemical Research

Fifteen 7,4’-O-modified genistein amino acid derivatives are synthesized through nucleophilic substitution and hydrolysis, followed by condensation with diverse amino acid esters. The antiproliferative activity of all the synthesized compounds is evaluated against three cancer cell lines (MGC-803, HeLa, HCT-116) and one normal cell line (HUVEC) using 5-fluorouracil (5-Fu) as the positive control. The results show that methyl [2-({5-hydroxy-3-[4-(2-{[3-(4-hydroxyphenyl)-1-methoxy-1-oxopropan-2-yl]amino}-2-oxoethoxy)phenyl]-4-oxo-4H-chromen-7-yl}oxy)acetyl] tyrosinate exhibits significant antiproliferative activity against the MGC-803 cell line with an IC₅₀ value of 8.52 µM, and its inhibitory effects on HeLa and HCT-116 cancer cells are stronger than that of the positive control drug 5-Fu.

The reactive zwitterionic intermediates, generated from addition of isoquinoline to alkyl propiolates, react with thiazolidin-2,4-dione to afford 3-[1-(2,4-dioxothiazolidin-3-yl)isoquinolin-2(1H)-yl]acrylates in good yields. Using (Z)-5-arylidenethiazolidine-2,4-diones as the NH-acidic component leads to 3-{1-[(Z)-5-benzylidene-2,4-dioxothiazolidin-3-yl] isoquinolin-2(1H)-yl}acrylates in moderate to good yields in the absence of any catalysts under mild reaction conditions. The reaction between quinoline, ethyl propiolate, and thiazolidin-2,4-dione leads to ethyl 3-[2-(2,4-dioxothiazolidin-3-yl) quinolin-1(2H)-yl]acrylate.

A novel, reactive, yellow fluorescent organosilicon dye, N-propyl-(diethoxy)methyl-silane-4-dimethylamino-naphthalimide, is designed and synthesized and is used to fabricate a covalently yellow fluorescent silicone oil by polycondensation of hydroxy-terminated polydimethylsiloxane. The chemical structure and optical properties of the N-propyl-(diethoxy)methyl-silane-4-dimethylamino-naphthalimide and covalently yellow fluorescent silicone oil are characterized by ¹H nuclear magnetic resonance, ¹³C nuclear magnetic resonance, mass spectrometry, Fourier transform infrared, UV–Vis, and fluorescence spectra. The results indicate that the fluorescence quantum yields of N-propyl-(diethoxy)methyl-silane-4-dimethylamino-naphthalimide and covalently yellow fluorescent silicone oil are 2.61% and 3.5%, respectively. The λ_max values of their dichloromethane solutions are 416 nm, and their λ_ex and λ_em are 430 and 509 nm, respectively. Furthermore, covalently yellow fluorescent silicone rubbers are prepared using tetraethoxysilane as a cross-linker, and some of their properties are investigated. Thermogravimetric analysis and dynamic mechanical analysis show that heat resistance and tan δ of the covalently yellow fluorescent silicone rubber are improved in comparison with silicone rubbers without N-propyl-(diethoxy)methyl-silane-4-dimethylamino-naphthalimide moieties. Solvent extraction experiments indicate that the solvent resistance of the covalently yellow fluorescent silicone rubber is much better than that of noncovalently yellow fluorescent silicone rubber.

The synthesis of C-ring hydrogenated sinomenine derivatives is accomplished from sinomenine by treatment with Zn-Hg/HCl, halogenation with NIS, and Heck reactions with various acrylates. A total of nine novel sinomenine cinnamate derivatives are obtained in 84%–93% yields. The structures of all the derivatives are characterized by ¹H NMR, ¹³C NMR, and MS spectroscopy.

The synthesis and characterization of a novel 6,13-dihydro-6,13-ethanopentacene-15,16-diimine palladium(II) complex are described. The effect of the backbone framework of the α-diimine metal catalyst on the polymerization reaction of norbornene and 1-octene is investigated. Compared to the 9,10-dihydro-9,10-ethanoanthracene-11,12-diimine palladium(II) complex (C1), the 6,13-dihydro-6,13-ethanopentacene-15,16-diimine palladium(II) complex (C2) with a polycyclic aromatic system on the backbone exhibits relatively high activities and leads to high molecular weights as well as narrow molecular weight distributions depending on the variation in feed ratios for copolymerization of norbornene and 1-octene. Moreover, the copolymers obtained using the 6,13-dihydro-6,13-ethanopentacene-15,16-diimine palladium(II) complex (C2) with large steric hindrance show high thermal stability and high glass transition temperatures.

A practical synthetic route to pimavanserin tartrate, in which the target compound was obtained with 99.84% purity and in 46% total yield via a 5-step synthesis starting from 4-hydroxybenzaldehyde and (4-fluorophenyl)methanamine, is reported. The main advantages of the route include inexpensive starting materials, mild reaction conditions and an acceptable overall yield.

A mild, efficient, and transition-metal-free catalytic strategy is developed to construct thioesters via selective N–C bond cleavage of Boc₂-activated primary amides. This strategy is successfully carried out with stoichiometric Na₂CO₃ as the base and provides the corresponding products in moderate to excellent yields.

Chalcopyrite is the most abundant, but also one of the most refractory, copper sources. One way to enhance chalcopyrite’s electrochemical dissolution is by mixing it with pyrite. To understand how and to what extent pyrite affects chalcopyrite’s electrochemical dissolution at different potentials, the electrochemical behaviors of chalcopyrite, pyrite, and chalcopyrite–pyrite couples in pH 1.8 H₂SO₄ were studied by potentiodynamic and electrochemical impedance spectroscopy. Potentiodynamic curves showed their different electrochemical reaction states and electrode surface characteristics. From open-circuit potential to 470 mV (vs saturated calomel electrode), chalcopyrite–pyrite was passivated with Cu_1−xFe_1−yS₂ ( y ≫ x ) ; from 470 to 580 mV, trans-passive dissolution occurred, and in the passive region, Cu_1−xFe_1−yS₂ transformed into Cu_1−x−zS₂; from 580 to 700 mV was an active region; and a pseudo-passive region was formed with CuS when the potential was above 700 mV. The smaller charge transfer resistance and passive resistance, as well as the smaller inductive relaxation, revealed how and to what extent the coupled pyrite accelerated the electrochemical dissolution of chalcopyrite.

A practical approach for the synthesis of cyclic phenyl hexayne is demonstrated through a one-pot deprotection/transformation of magnesium acetylide into a copper acetylide/Sonogashira coupling procedure, followed by dephosphination, Hay coupling, desilylation, and Eglinton coupling. This approach avoids tedious synthetic routes and harsh reaction conditions and affords the product in 41% yield.

Nitrogen-doped carbon dots were synthesized using citric acid monohydrate and glutathione as raw materials. The synthesized nitrogen-doped carbon dots were characterized by multiple analytical techniques, including transmission electron microscopy, Fourier transform infrared spectroscopy, ultraviolet–visible absorption spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, and fluorescence spectra. The fluorescence intensity of the nitrogen-doped carbon dots gradually quenched with different concentrations of Cu²⁺ ions. The effect of the pH value, the nitrogen-doped carbon dot concentration, and the reaction time on the fluorescence intensity of the N-CDs-Cu²⁺ system was investigated, and the experimental conditions were optimized. A rapid and sensitive method for the determination of Cu²⁺ ions was established that exhibited a good linearity in the concentration range 0.20–200.0 μM with a detection limit of 0.27 nM. Meanwhile, the fluorescence quenching mechanism of the interaction between nitrogen-doped carbon dots and Cu²⁺ was preliminarily discussed. The method was used to detect trace Cu²⁺ in tap water and lake water, with recoveries ranging from 98.1% to 102.0%. Furthermore, due to low cytotoxicity and good biocompatibility, nitrogen-doped carbon dots as a probe were also successfully used in bioimaging.

Three new aromatic compounds named fistuloates: A (3-butyl-6-ethylnonyl-3-(1-phenylethyl) benzoate), B (3-(6-tert-butyl-1-ethoxy-5-ethyl-4-methylnonyl)-5-ethylbenzoic acid isobutyl ester) and C (4,5-diethoxy-2-propylbenzoic acid 7-(6-pentyltetrahydropyran-2-yl)-heptyl ester) were isolated from the ethyl acetate soluble fraction of Cassia fistula Linn. The structural formulae of the isolated compounds A–C were established through interpretation of their spectral data. Compounds A–C exhibited significant antioxidant properties in 2,2-diphenyl-1-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and superoxide anion radical scavenging assays that signifies that C. fistula carries potential anti-oxidant constituents and may assist to cure diseases associated with oxidative stress and others.

Novel and efficient synthetic strategies are developed for the first synthesis of two new impurities found in obeticholic acid. The synthetic routes to the impurities are designed without column purification using 4-nitrobenzoyl chloride as a selective protecting group. The impurities, which are obtained in good yields and high purity, are identified and characterized using high-resolution mass spectrometry, Fourier transform infrared, one-dimensional nuclear magnetic resonance (¹H, ¹³C, distortionless enhancement by polarization transfer), and two-dimensional nuclear magnetic resonance (Correlated Spectroscopy, heteronuclear single quantum coherence, heteronuclear multiple bond correlation, and rotating-frame Overhauser effect spectroscopy) techniques.

(+)-Demethoxyaspidospermine was synthesized via the acylation of aspidospermidine with acetic anhydride, and the structure was determined by elemental analysis and Fourier-transform infrared and nuclear magnetic resonance spectroscopic tools and was supported by the simulated spectroscopic studies. Next, the stable geometries obtained by the conformational analysis performed at the B3LYP/6-31G(d, p) level were used for further investigations carried out in B3LYP and M06-2X functionals, and Hartree–Fock (HF) method, employed by the 6-311++G(d, p) basis set. Also, the natural bond orbital analysis revealed that the most contribution to the lowering of the stabilization energy came from n → π* and π → π* interactions. Moreover, the non-linear optic analysis has shown that the title compound can be a useful agent in the optoelectronic devices because of the optical properties. Also, the chemical reactivity tendency for nucleophilic or electrophilic attack reactions on the compound was evaluated by frontier molecular orbital analysis, and the reactive sites of the compound was shown by highest molecular orbital and lowest unoccupied orbital amplitudes and molecular electrostatic potential diagrams.

A new method for the synthesis of indolin-2-ones has been realized by an I₂-promoted oxidative reaction from 1,2,3,3-tetramethyl-3H-indolium iodides. This transformation proceeded smoothly under metal-free and peroxide-free conditions in a cascade manner.

2,4-Dichlorophenylacetic acid is synthesized in high yield via the carbonylation of 2,4-dichlorobenzyl chloride, and various experimental conditions are evaluated. Xylene, bistriphenylphosphine palladium dichloride, tetraethylammonium chloride and sodium hydroxide in solution are added to the reaction system and held at 80 °C under a CO atmosphere. 2,4-Dichlorophenylacetic acid is obtained in a maximum yield of 95%, and a mechanism for 2,4-dichlorobenzyl chloride carbonylation is proposed. The reaction system provides a mild, effective and novel means by which to prepare phenylacetic acid derivatives from their corresponding benzyl chloride derivatives.

A convenient method for the preparation of Coenzyme Q₁ from cheap and readily available 3,4,5-trimethoxytoluene is developed. Coenzyme Q₁ is synthesized in a moderate yield by a two-step procedure involving the key reaction of an allyl bromide with Coenzyme Q₀ through a redox chain reaction. The reaction is efficient and can be used for the synthesis of other Coenzyme Q compounds.

Enantioselective synthesis of α-amino esters have been achieved through the Petasis borono-Mannich multicomponent reaction using (R)-BINOL-derived catalysts with stable heteroaryl and alkenyl trifluoroborate salts under mild conditions. The reaction provides direct access to optically active α-amino esters with moderate to good yields and enantioselectivities.

The oxidation of 1,2,4-trimethylbenzene with phthaloyl peroxide has been investigated under solvent-free and optimized conditions. 2,3,5-Trimethylbenzoquinone was obtained with great purity in 92% yield at 95% conversion of 1,2,4-trimethylbenzene at 120°C for 2.5 h under solvent-free conditions. The important factors such as the efficiency of the different cyclic acid anhydrides or carboxylic acid peroxides, the concentration of phthalic anhydride and 30% H₂O₂, the reaction time, the effect of solvent system, and the reaction temperature have been studied. An important advantage of this oxidizing system, aside from the organic solvent-free conditions, is that it is non-toxic, eco-friendly, and inexpensive. In addition, this methodology will be of great use in the preparation of commercially valuable benzoquinones from the corresponding aromatic compounds.