Pd-catalyzed ligand-free C(5)–H arylation of 1,4-disubstituted 1,2,3-triazoles promoted by microwaves

Pd(OAc)₂-catalyzed regioselective C(5)–H arylation of 1,4-disubstituted 1,2,3-triazoles was achieved without ligand under microwave conditions in 1?h, generating 1,4,5-trisubstituted 1,2,3-triazoles with good to excellent yields. The obtained molecules can be easily converted into 4,5-disubstituted 1,2,3-triazoles through the debenzylation process with one-pot manipulation.     

Sensitive flow-injection chemiluminescence determination of terbutaline sulfate based on enhancement of the luminol–permanganate reaction

A novel and highly sensitive chemiluminescence (CL) method for the determination of terbutaline sulfate, coupled with flow-injection analysis (FIA), is described in this paper. The method is based on enhancement by terbutaline sulfate of the chemiluminescence emission of the luminol–permanganate system under alkaline conditions. Under the conditions selected the concentration of terbutaline sulfate is proportional to CL intensity in the range 5×10^–10–5×10^–7 g mL^–1, with a detection limit of 1.7×10^–10 g mL^–1 (3). The relative standard deviation is 2.8% for 1×10^–8 g mL^–1 terbutaline sulfate (n=11). Ninety samples can be determined per hour. The proposed method has been used to determine terbutaline sulfate in pharmaceutical preparations and in plasma and urine samples with satisfactory results. The possible mechanism of the chemiluminescence reaction is discussed briefly.     

The synthesis of new 1,3-oxazolidines and 1,3-oxazinanes containing (η<Superscript>6</Superscript>-arene)tricarbonylchromium group based on condensation between aldehydes and amino alcohols

The condensation reactions of β- and γ-amino alcohols containing phenyl or (η⁶-arene) tricarbonylchromium substituent with formaldehyde, acetaldehyde, benzaldehyde, and (η⁶-benzaldehyde)tricarbonylchromium were studied. The resulting 1,3-oxazolidine and 1,3-oxazinane products were isolated in a pure form and identified by different physicochemical methods. The effect of (η⁶-arene)tricarbonylchromium moiety on the reaction process was demonstrated.     

Prediction of allergic reaction risk of Shenmai injection based on real-world evidence coupled with UPLC–Q-TOF-MS

The allergic reaction (AR) of Chinese herbal injection (CHI) has become one of the most noticeable focuses of public health in China. However, it still remains a considerable controversy as to whether low-molecular-weight components in CHI have potential sensitization. In this study, the relationship between AR and low-molecular-weight component profile of Shenmai injection was explored by an interdisciplinary technology integrating real-world evidence and ultra-performance liquid chromatography–quadrupole time-of-flight mass spectroscopy (UPLC–Q-TOF-MS). The AR information of hospitalized patients was obtained by comprehensively analyzing real-world evidence from January 2015 to June 2019 at two Chinese hospitals. The UPLC–Q-TOF-MS was exploited to systematically investigate the low-molecular-weight component profile with 50–1500 m/z mass range, and 3725 MS1 peaks were detected. The optimized partial least squares discriminant analysis model was established to map the influence of low-molecular-weight components on AR. The results of this study showed that high levels of organic acids administered intravenously might be a potential risk factor for inducing AR. By using this method, Shenmai injection with high AR risk could be recognized precisely with 100% accuracy before clinical use.     

Reaction of 2′-hydroxy-1,1′: 3′,1″-terphenyl-5′-carbaldehyde with naphthalen-1-amine,quinolin-8-amine,and 1,3-diketones

Condensation of 2′-hydroxy-1,1′: 3′,1″-terphenyl-5′-carbaldehyde with naphthalen-1-amine and cyclohexane-1,3-dione, methyl 2,2-dimethyl-4,6-dioxocyclohexane-1-carboxylate, or dimedone gave the corresponding 7-(2′-hydroxy-1,1′: 3′,1″-terphenyl-5′-yl)-7,8,9,10,11,12-hexahydro-12H-benzo[c]acridin-8-ones. The reaction of 2′-hydroxy-1,1′: 3′,1″-terphenyl-5′-carbaldehyde with naphthalen-1-amine and indan-1,3-dione produced 7-(2′-hydroxy-1,1′: 3′,1″-terphenyl-5′-yl)-8H-benzo[h]indeno[1,2-b]quinolin-8-one. 7-(2′-Hydroxy-1,1′: 3′,1″-terphenyl-5′-yl)-7,8,9,10,11,12-hexahydrobenzo[b][1,10]phenanthrolin-8-ones were obtained by three-component condensation of 2′-hydroxy-1,1′: 3′,1″-terphenyl-5′-carbaldehyde with quinolin-8-amine and cyclohexane-1,3-dione, methyl 2,2-dimethyl-4,6-dioxocyclohexane-1-carboxylate, or dimedone.     

The synthesis of ZnP4 based on liquid–solid reaction under high pressure and temperature

In this article we reported the successful high pressure and temperature synthesis of micron-sized zinc tetraphosphide (ZnP₄) crystals based on the liquid–solid reaction between Zn and P at a large-volume cubic press. Techniques of X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDXA) were employed to investigate the phase structure, grain size, morphology and stoichiometric ratio of crystals. The results indicate that the synthesized ZnP₄ has a tetragonal structure with the space group of P41212, and the grains with size of about 50 μm can be prepared at 4.0 GPa and 1000 °C. We also obtained the pressure–temperature (P–T) formation region of ZnP₄ and discussed the formative mechanism of ZnP₄ crystals.     

Structure–reactivity relationship in bimolecular elimination reactions based on the condensed graph of a reaction

By means of a structural representation of the chemical reactivity as a condensed graph a model predicting rate constants of the bimolecular elimination reaction is derived for the first time. The model developed enables the prediction of rate constants of reactions proceeding in different solvents or water-organic mixtures at different temperatures. It demonstrates a good predictive performance: a mean square deviation of predicted values from experimental ones is less than 0.7 logarithmic units. An outlier analysis shows that prediction errors are mainly due to the imperfection of the training data containing unique reactions. The model is available for users at arsole.u-strasbg.fr.     

Spectrofluorimetric determination of formaldehyde by a flow-injection method based on its catalytic effect on the acridine yellow–bromate reaction

A flow-injection configuration for the determination of formaldehyde is proposed. The method is based on the enhancing effect of formaldehyde on the oxidation of acridine yellow by bromate in acidic medium. The proposed procedure is simple, inexpensive, sensitive and suitable for concentrations of formaldehyde between 1 and 56 microg mL(-1). A sampling-rate of 60 samples h(-1) was achieved. The effect of several organic and inorganic species was studied. The method was applied to the determination of formaldehyde in pharmaceuticals, milk and air in work environments. The accuracy of the method was confirmed by comparing the results with those obtained using the standard acetylacetone method.     

Electrosynthesis of nanocomposite polymer coatings based on 1-vinyl-1,2,4-triazole–crotonaldehyde copolymers

Russian Journal of Applied Chemistry - The possibility of electrochemical preparation of metal–polymer nanocomposites and coatings on pure iron and steel electrode by combining the...     

Electrooxidation of 1,3–di(para-tolyl)-5-para-toluidinomethyl-1,3,5-diazaphosphorinane on soluble metallic anodes

Electrochemical oxidation of 1,3–di(para-tolyl)-5-para-toluidinomethyl-1,3,5-diazaphosphorinane on various soluble metallic anodes (Al, Cu, Ni) was investigated. Influence on the electrochemical process of such factors as the nature of the metal, anode potential of electrolysis and amount of the passed electricity was established.     

Organocatalytic formal [5+1] annulation: diastereoselective cascade synthesis of functionalized six-membered spirocyclic indane-1,3-diones/oxindoles via Michael–aldol reaction

An efficient cascade protocol has been developed for the diastereoselective synthesis of functionalized six-membered spirocyclic compounds. The reaction proceeded smoothly between indane 1,3-diones/oxindoles/coumaranone as the dinucleophilic components and (E)-5-nitro-6-aryl-hex-5-en-2-one as the dielectrophile to give the desired products with reasonable to high chemical yields (30–84%) and high levels of diastereoselectivities (upto >95:5 dr). The reaction proceeded smoothly via cascade Michael–aldol reaction.     

Substituted benzoquinazolinones. Part 1: Synthesis of 6-aminobenzo[h]quinazolinones via Buchwald–Hartwig amination from 6-bromobenzo[h]quinazolinones

6-(Morpholin-4-yl)benzo[h]quinazolin-4(3H)-one derivatives 18a,b were prepared under Buchwald–Hartwig conditions by reacting 6-bromobenzo[h]quinazolin-4(3H)-ones 13a,b with morpholine in the presence of a Pd(OAc)₂/XantPhos system in 1,4-dioxane as solvent. The starting 6-bromobenzo[h]quinazolin-4(3H)-ones 13 were synthesized via condensation of the ethyl 1-amino-4-bromonaphthalene-2-carboxylate (11) with formamide (Niementowski reaction), and then reaction of the obtained benzoquinazolinone 9 with appropriates benzyl bromides. Compound 11 was prepared using a three-step procedure involving (a) metalation of the N-Boc- or N-Piv-protected 1-aminonaphthalenes with t-BuLi, followed by reaction with ethyl chloroformate, (b) bromination of the naphthalene ring of ester 3 using NBS, and next (c) deprotecion of the amine group with TFA or HCl. Biological screening of the potential cytotoxicity of compounds 8, 9, 18b on A549 and HT29 cell lines, as well as on the lymphocytes showed that compound 18b has interesting anticancer activities. The detailed synthesis, spectroscopic data, and biological assays were reported.     

Unexpected reduction of the nitro group in (3-nitrophenyl)-1,2,4-triazines during their aza-Diels–Alder reaction with 1-morpholinocyclopentene

Unexpected reduction of the nitro group to the amino one during aza-Diels–Alder reaction between (3-nitrophenyl)-1,2,4-triazines and 1-morpholinocyclopentene (neat, 200 °C, argon) occurred to furnish 4-(3-aminophenyl)-6,7-dihydro-5H-cyclopenta[c]pyridines.     

Unexpected direct formation of a bridging 4-cyanobuta-1,3-dienylidene group from reaction of [(C5H5)Fe(CO)]2(μ-CCH2) with HCCCN

The ethenylidenediiron complex [C₅H₅Fe(CO)]₂ (μ-CO)(μ-CCh₂) reacts with the nitrile substituted alkyne HCCCn to give high yield of [(C₅H₅)Fe(CO)]₂ (μ-CO)(μ-CCHCHC(CN)H). It is suggested that this bridging 4-cyanobuta-1,3-dien-ylidenediiron complex is formed by attack of the electron rich double bond of the ethenylidenediiron complex on the electrophilic protonated carbon of the alkyne. An IR study has indicated that hydride reduction of the complex occurs selectively at the bridging vinylidene carbon atom to give am anionic bridging cyanovinylalkylidenediiron complex.     

Gas Hydrate Frameworks of Allen's Polyhedra. 1. Frameworks on 3–5 Nets

The structures of water molecule frameworks built up of 5¹², 5¹²6², 5¹²6³, and 5¹²6⁴ polyhedra are discussed. In the frameworks of such polyhedra, it is possible to distinguish layers; the centers of the polyhedra belonging to a layer are at the nodes of a planar network consisting of triangular, pentagonal, and hexagonal meshes. The structure of one layer entirely determines the structure of the whole framework. An analysis is given of the structure and topology of frameworks whose layers are constructed on pentagontrigonal nets. It is shown that these frameworks can be constructed from two types of polyhedral blocks closely packed in space.     

Solvent-free reaction of 1,2,4-triazine-5-carbonitriles with 4-(cyclohex-1-en-1-yl)morpholine. Unexpected decyanation in addition to classical aza-Diels–Alder reaction

The reaction of 1,2,4-triazine-5-carbonitriles with 4-(cyclohex-1-en-1-yl)morpholine under solventfree conditions has been found to follow two pathways: aza-Diels–Alder reaction and unexpected decyanation of the initial nitriles. The scope of the revealed decyanation reaction has been roughly estimated.     

A density functional theory study on the reaction mechanism of hydrazones with α-oxo-ketenes: Comparison between stepwise 1,3-dipolar cycloaddition and Diels–Alder pathways

Density functional theory calculations have been performed at the B3LYP/6-311+G(d,p) and M06-2X/6-31G(d,p) levels to obtain an insight into the nature of the stepwise cycloaddition reactions of hydrazones with α-oxo-ketenes. Three reaction pathways are possible, two Diels–Alder reactions and a 1,3-dipolar cycloaddition (1,3-DC) reaction. Despite the high energy required for 1,2-hydrogen shift in hydrazone to form an azomethine imine, 1,3-DC reaction among the possible pathways is the most favorable. The mechanism has been explained on the basis of transition state stabilities, global and local reactivity indices of the reactants, intrinsic reaction coordinate calculation, and the electron localization function topological analysis of the bonding changes along the 1,3-DC reaction. The computed free energies and enthalpies agree with the experimental outcome.