1,3‐Dichloro‐tetra‐n‐butyl‐distannoxane: a new application for catalyzing the direct substitution of 9H‐xanthen‐9‐ol at room temperature

1,3‐Dichloro‐tetra‐n‐butyl‐distannoxane was firstly used to catalyze the direct substitution of 9H‐xanthen‐9‐ol with indoles at room temperature to afford a class of 3‐(9H‐xanthen‐9‐yl)‐1H‐indole derivatives in good to excellent isolating yield. Moreover, other nucleophiles (such as diketone and pyrrole) could also proceed smoothly in this methodology. Copyright © 2012 John Wiley & Sons, Ltd.     

Analysis and Identification of the Chemical Constituents of Ding‐Zhi‐Xiao‐Wan Prescription by HPLC‐IT‐MSn and HPLC‐Q‐TOF‐MS

Ding‐Zhi‐Xiao‐Wan (DZXW) is a famous traditional Chinese medicine (TCM) formula, which is composed of four herbs, Ginseng Radix, Poria, Polygala Radix and Acori Tatarinowii Rhizoma. It has been popularly used for the treatment of emotional disease, like Alzheimer's disease, Parkinson's disease, depression, anxiety, forgetfulness and neurasthenia. In this research, a high‐performance liquid chromatography coupled with ion‐trap tandem mass spectrometry (HPLC‐IT‐MSⁿ) method along with a high‐performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry (HPLC‐Q‐TOF‐MS) method in negative ion mode was established to investigate the major constitutions in DZXW. The extracts were prepared by ultra‐sonication in ethyl acetate, n‐butanol, 95% ethanol and deionized water sequentially as well as in deionized water directly. A Kromasil C18 column was used to separate the extracts of DZXW. Acetonitrile and 0.1% aqueous formic acid (V/V) were used as the mobile phase. A total of 64 components were characterized, including 16 triterpenoids, 14 Polygala saponins, 10 oligosaccharide esters, 6 sucrose esters, 2 xanthone C‐glycosides and 16 ginsenosides.     

Improved Synthesis of 2,2‐Arylmethylene Bis(3‐hydroxy‐5,5‐dimethyl‐2‐cyclohexene‐1‐one) and 1,8‐Dioxo‐octahydroxanthene Derivatives Catalyzed by Electrogenerated Base and Sulfuric Acid

An efficient method has been developed for the synthesis of 1,8‐dioxo‐octahydroxanthene derivatives in two‐step. In the first step, the electrogenerated base (EGB) catalyzed multicomponent transformation of dimedone and aromatic aldehydes in an undivided cell in the presence of sodium bromide as an electrolyte into 2,2′‐arylmethylene bis(3‐hydroxy‐5,5‐dimethyl‐2‐cyclohexene‐1‐one) at room temperature. In the second step, H₂SO₄ was employed as a dehydrating reagent for the cyclization process to give symmetrical heterocycles 1,8‐dioxo‐octahydroxanthene derivatives. Short reaction time, convenient work up, and using of inexpensive reagents, simple equipment, novel and eco‐friendly procedure make this strategy more useful for the preparation of xanthene derivatives.     

Electrochemical Behavior of a Crown Type Polyether: 2,5,8‐Trioxa‐16,20‐Diazatricyclo[20.4.0.09,14]‐Hexacosa‐9,11,13,15,20,22,24,26‐Octaene

In this work, electrochemical behaviors of 2,5,8‐trioxa‐16,20‐diazatricyclo[20.4.0.0^9,14]‐hexacosa‐9,11,13,15,20,22,24,26‐octaene (TPO) was investigated and mechanistic study was achieved in 0.1 M tetrabutylammonium tetrafluoroborate (TBATFB) in acetonitrile on glassy carbon (GC) working electrode by cyclic voltammetry, chronoamperometry and chronocoulometry. It was estimated by ultra microelectrode (UME) that this molecule is reduced by four‐electron transfer. The reduction product adsorbed on the electrode surface, characterized by Raman spectroscopy, is a dimer. It was determined by using cyclic voltammetry that TPO is electroreduced by EC mechanism. Using digital simulation studies, EC mechanism was also indicated and the standard rate constant of the reduction step was calculated as well as the rate constants of the homogenous reaction.     

Synthesis of 9‐Methyl‐11H‐pyrido[2,1‐b]quinazolin‐11‐one Using the Ullmann Condensation

The Ullmann condensation between 2‐chlorobenzoic acid and 2‐amino‐6‐methyl pyridine in DMF as solvent yielded 2‐[(6‐methyl‐2‐pyridinyl)amino] benzoic acid. The cyclization of this acid gave two isomers, the 9‐methyl‐11H‐pyrido[2,1‐b]quinazolin‐11‐one and, in a minor quantity, 2‐methylbenzo[b][1,8]naphtyridin‐5(10H)‐one. Using ultrasound irradiation the pyridoquinazolin‐11‐one was obtained as the sole product.     

Synthesis and Antimicrobial Activity of Novel Quinoxaline Derivatives

In this study, certain 3‐substituted styrylquinoxalin‐2(1H)‐ones ( 2a‐d ) and their 2‐chloro ( 3a‐d ) and 2‐piperazinyl derivatives ( 4a‐g ) were synthesized from 3‐methylquinoxalin‐2(1H)‐one ( 1 ). In addition, a series of 1‐alkyl‐3‐substituted styrylquinoxalin‐2(1H)‐ones ( 5a‐d ) was also prepared. Moreover, 3‐(N²‐arylidenehydrazinocarbonyl)quinoxalin‐2(1H)‐ones ( 8a‐c ) as well as their cyclized oxadiazolinyl derivatives ( 9a‐c ) were prepared from 3‐hydrazinocarbonylquinoxalin‐2(1H)‐one ( 7 ). Furthermore, 3‐(5‐substituted thio‐1,3,4‐oxadiazol‐2‐yl)quinoxalin‐2(1H)‐ones ( 11a‐c ) and ( 12a‐c ) were obtained from the intermediate compound ( 10 ) ‐ previously obtained via cyclization of ( 7 ) with CS₂. Likewise, 3‐(5‐oxo‐4,5‐dihydro‐(1,3,4‐oxadiazol‐2‐yl)quinoxalin‐2(1H)‐one ( 13 ), 3‐[5‐(4‐nitrophenyl)‐1,3,4‐oxadiazol‐2‐yl]‐quinoxalin‐2(1H)‐one ( 14 ) and its 2‐chloro derivative ( 15 ) were prepared from 3‐hydrazinocarbonylquinoxalin‐2(1H)‐one ( 7 ). Some of these derivatives were evaluated for antimicrobial activity in vitro and some of the tested compounds showed antibacterial or antifungal activity.     

Determination of thiol compounds by HPLC and fluorescence detection with 1,3,5,7‐tetramethyl‐8‐bromomethyl‐difluoroboradiaza‐s‐indacene

Altered levels of thiols in biological fluids are considered to be an important indicator for several diseases. In this article, 1,3,5,7‐tetramethyl‐8‐bromomethyl‐difluoroboradiaza‐s‐indacene is proposed as a fluorescent derivatization reagent for the determination of thiols including glutathione, cysteine, N‐acetylcysteine, and homocysteine by HPLC. Under the optimized derivatization and separation conditions, a baseline separation of all the four derivatives has been achieved using isocratic elution on an RP C₈ column within 26 min. With fluorescence detection at 505 and 525 nm for the excitation and emission, respectively, the LODs (S/N = 3) are from 0.2 nM (glutathione) to 0.8 nM (cysteine). The feasibility of this method in real samples has been evaluated by the determination of thiols in human plasma from the healthy persons and hypertensive patients with recoveries of 92–105.3%.     

A 2‐D‐HPLC‐CE platform coupled to ESI‐TOF‐MS to characterize the phenolic fraction in olive oil

A 2‐D‐HPLC/CE method was developed to separate and characterize more in depth the phenolic fraction of olive oil samples. The method involves the use of semi‐preparative HPLC (C18 column 250×10 mm, 5 μm) as a first dimension of separation to isolate phenolic fractions from commercial extra‐virgin olive oils and CE coupled to TOF‐MS (CE‐TOF‐MS) as a second dimension, to analyze the composition of the isolated fractions. Using this method, a large number of compounds were tentatively identified, some of them by first time, based on the information concerning high mass accuracy and the isotopic pattern provided by TOF‐MS analyzer together with the chemical knowledge and the behavior of the compounds in HPLC and CE. From these results it can be concluded that 2‐D‐HPLC‐CE‐MS provides enough resolving power to separate hundreds of compounds from highly complex samples, such as olive oil. Furthermore, in this paper, the isolated phenolic fractions have been used for two specific applications: quantification of some components of extra‐virgin olive oil samples in terms of pure fractions, and in vitro studies of its anti‐carcinogenic capacity.     

Мulticomponent Reactions of NH4Cl,CH2O and SH‐acids in Water as Effective Synthesis of Biologically Active Heterocycles

Multicomponent reactions of ammonium chloride in water with formaldehyde and SH‐acids (H₂S, ethane‐1,2‐dithiol) proceed with selective formation of such heterocycles as 3,7‐dithia‐1,5‐diazabicyclo[3.3.1nonane, 3‐(1,5,3‐dithiazepan‐3‐ylmethyl)‐1,5,3‐dithiazepanе and 1,6‐bis‐(1,5,3‐dithiazepan‐3‐yl)‐2,5‐disulphanylhexane. With participation of 1,3‐propanedithiol, this reaction leads to the formation of three‐dimensional hetero(S,N)‐chain polymer. The antifungal activity of 3,7‐dithia‐1,5‐diazabicyclo[3.3.1]nonane against microscopic fungi Bipolaris sorokiniana, Fusarium oxysporum and Aspergillus niger and same for 1,6‐bis‐(1,5,3‐dithiazepan‐3‐yl)‐2,5‐disulphanylhexane against Botrytis cinerea and Rhizoctonia solani was evaluated.     

Heck reactions of aryl halides with alk‐1‐en‐3‐ol derivatives catalysed by a tetraphosphine–palladium complex

cis,cis,cis‐1,2,3,4‐Tetrakis(diphenylphosphinomethyl)cyclopentane–[PdCl(C₃H₅)]₂ efficiently catalyses the Heck reaction of alk‐1‐en‐3‐ol with a variety of aryl halides. In the presence of hex‐1‐en‐3‐ol or oct‐1‐en‐3‐ol, the β‐arylated carbonyl compounds were selectively obtained. Turnover numbers up to 84 000 can be obtained for this reaction. Linalool and 2‐methylbut‐3‐en‐2‐ol led regio‐ and stereoselectively to the corresponding (E)‐1‐arylalk‐1‐en‐3‐ol derivatives. A minor electronic effect of the substituents of the aryl bromide was observed. Quite similar reaction rates were generally observed in the presence of activated aryl bromides such as bromoacetophenone and deactivated aryl bromides such as bromoanisole, indicating that, with these alkenols and this catalyst, the oxidative addition of aryl bromides to palladium is not the rate‐limiting step. It should be noted that this reaction also proceeds with sterically very congested aryl bromides such as 9‐bromoanthracene or 2,4,6‐triisopropylbromobenzene or with a vinyl bromide. On the other hand, low yields were obtained with aryl chlorides. Copyright © 2006 John Wiley & Sons, Ltd.     

Ionic liquids as novel and green media for clean synthesis of soluble aromatic‐aliphatic poly(amide‐ester)s containing hydroxynaphthalene urazole moiety

Ionic liquids (IL)s are very attractive and environmentally acceptable solvents. They can be used as green media for a number of chemical processes. In this investigation, for the advancement of ecological safety and improvement of technological ability of this process, room temperature ionic liquids (RTIL)s and quaternary ammonium salt, tetrabutylammonium bromide (TBAB) have been used both as an environmentally benign solvent and catalyst for the polycondensation 4‐(3‐hydroxynaphthalene)‐1,2,4‐triazolidine‐3,5‐dione ( 3HNTD ) with aliphatic diacid chlorides, eliminating the need for a volatile organic solvent (VOS) and additional catalyst. The reaction of monomer 3HNTD with acetyl chloride was performed in N,N‐dimethylacetamide solution at different molar ratios, and the resulting mono‐, di‐, and trisubstituted derivatives were obtained in high yields and were finally used as models for polymerization reactions. The effects of various reaction parameters, such as the nature of the ILs, the amount of ILs, the reaction temperature, and the reaction time, on the yields and inherent viscosities of the resulting poly(amide‐ester)s (PAE)s were studied. Polycondensation reactions successfully proceeded in IL without any additional extra components, such as triethylamine or pyridine, which are used in similar reactions in organic solvents. Therefore, ILs can act both as solvent and catalyst. In addition to the solubility test, inherent viscosity as a measure of molecular weight was determined. PAEs were obtained in high yields with inherent viscosities ranging from 0.18 to 0.34 dl g^?1. This method was also compared with conventional method for the synthesis of PAEs. Fluorimetric studies of the model compound as well as polymers were performed. Copyright © 2008 John Wiley & Sons, Ltd.     

Determination of thiols by capillary micellar electrokinetic chromatography with laser induced fluorescence detection using 1,3,5,7‐tetramethyl‐8‐phenyl‐(4‐iodoacetamido) difluoroboradiaza‐s‐indacene as labeling reagent

A sensitive and effective micellar electrokinetic capillary chromatography with laser‐induced fluorescence detection approach was described for the determination of low molecular‐mass thiols using 1,3,5,7‐tetramethyl‐8‐phenyl‐(4‐iodoacetamido) difluoroboradiaza‐s‐indacene as the labeling reagent. After precolumn derivatization, baseline separation of six thiol compounds including cysteine, glutathione, N‐acetylcysteine, homocysteine, 6‐mercaptopurine, and penicillamine were achieved within 18 min. The optimal running buffer was composed of mixtures involving 25 mM sodium dodecyl sulfate, 25% (v/v) acetonitrile and 15 mM sodium phosphate buffer, pH 7.5. The detection limits (S/N = 3) were found as low as 40 pM under argon ion laser‐induced fluorescence detector (λ_ex/λ_em = 488/520 nm), which were much better than the reported approaches. The accuracy and specificity of this assay for real samples were assured by a standard addition method. The proposed method has been applied to the analysis of thiols both in human plasma and plum flower samples with recoveries of 92.0–109.4%.     

2‐(2‐Aminoethylamino)‐5‐nitropyridine as a basic matrix for negative‐mode matrix‐assisted laser desorption/ionization analysis of phospholipids

Fast and easy analysis of phospholipids (PLs) by matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) has been well demonstrated. However, when using common organic matrices, such as 2,5‐dihydroxybenzoic acid (DHB), the detection of most PL classes in positive‐ion mode is difficult when PLs containing zwitterionic groups, such as phosphatidylcholines (PCs) and sphingomyelins (SMs) are present. To reduce this limitation, 2‐(2‐aminoethyloamino)‐5‐nitropyridine (AAN), a basic compound, was evaluated as an alternative matrix. Negative‐ion spectra showed enhanced detection of phosphatidyl ethanolamines (PEs), phosphatidyl serines (PSs), phosphatidyl glycerols (PGs), and phosphatidyl inositols (PIs) in simple mixtures and in a crude methanolic soybean extract. The relative ionization efficiency (RIE) was highest for PIs and lowest for PGs, PSs, and PEs. Compared to DHB and para‐nitroaniline, AAN resulted in greater sensitivity for the detection of PL classes in the negative mode. Indeed, the S/N ratio was nearly an order of magnitude higher than that reported for similar PI concentrations but with DHB. MALDI spots produced with AAN were homogeneous thus allowing automation and improved reproducibility. Positive‐mode traces could also be acquired with AAN as the matrix, but with lower sensitivity than in the negative mode. Copyright © 2008 John Wiley & Sons, Ltd.     

Palaeophytochemical Components from the Miocene‐Fossil Wood of Pinus Griffithii

Some Miocene‐fossil wood of Pinus griffithii preserved as lignified wood in brown coal was found in an open coalmine in Xundian of Yunnan Province, China. To explore its chemical components, here we show the palaeophytochemical investigation of this Pliocene‐fossil wood of P. armandii, resulting in the isolation of 11 compounds ( 1–11 ) including one new compound named 3,3‐dimethoxy‐24‐ethyl‐cholestan ( 1 ) by liquid column chromatography. Furthermore, sixteen volatiles were detected from this fossil wood by gas chromatography‐mass spectrometry (GC‐MS). These structures of 11 compounds were elucidated by analysis of their MS, 1D and 2D‐NMR spectra, and comparison with published data.     

Solvent‐free Synthesis of 1,8‐Dioxo‐octahydroxanthenes and Tetra‐hydrobenzo[a]xanthene‐11‐ones over Poly(N,N′‐dibromo‐N‐ethylnaphtyl‐2,7‐sulfonamide)

In this work, poly(N,N ′‐dibromo‐N ‐ethylnaphtyl‐2,7‐sulfonamide) (PDNES ) as a highly efficient catalyst was applied for the synthesis of 1,8‐dioxo‐octahydroxanthenes and tetra‐hydrobenzo[a]xanthene‐11‐ones under neutral and solvent‐free conditions.     

Oxazoline‐terminated macromonomers by the alkylation of 2‐methyl‐2‐oxazoline

Well‐defined macromonomers of poly(ethylene oxide) and poly(tert‐butyl methacrylate) were obtained by anionic polymerization induced directly by the carbanion issued from 2‐methyl‐2‐oxazoline. When ethylene oxide was added to this carbanion with lithium as the counterion, a new compound able to initiate the polymerization of ε‐caprolactone in an anionically coordinated way was synthesized, and this led to well‐defined poly(ε‐caprolactone) macromonomers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2440–2447, 2005     

A One‐Pot Synthesis of 1,3‐Dihydro‐1,3,3‐tris(perfluoroalkyl)isobenzofuran‐1‐olates and Their Complete NMR Spectroscopic Analysis on the Basis of 1D and 2D Experiments

A convenient synthesis of the 1,3‐dihydro‐1,3,3‐tris(perfluoroalkyl)isobenzofuran‐1‐ols 3a , b was elaborated starting from commercially available phthaloyl dichloride and trimethyl(perfluoroalkyl)silanes (Me₃SiR_f) 1a , b (R_f=CF₃, C₂F₅) in the presence of a fluoride source (Schemes 1 and 3). In a reaction analogous to alkyl Grignard reagents, double chloride substitution by two perfluoroalkyl groups and subsequent addition of one perfluoroalkyl group with concomitant ring closure led to this new class of compounds (Scheme 2). The syntheses of the alcohols and some alcoholates, as well as of the corresponding trimethylsilyl ethers are described. A combination of special 1D and 2D NMR experiments allowed the assignment of all atoms of the new compounds. The solid‐state structure of 1,3‐dihydro‐1,3,3‐tris(trifluoromethyl)isobenzofuran‐1‐ol ( 3a ) was elucidated by X‐ray diffraction methods.     

Synthesis of multifunctional polymer containing Ni‐Pd NPs via thiol‐ene reaction for one‐pot cascade reactions

Recently, acid–base bifunctional catalysts have been considered due to their abilities, such as the simultaneous activation of electrophilic and nucleophilic species and their high importance in organic syntheses. However, the synthesis of acid–base catalysts is problematic due to the neutralization of acidic and basic groups. This work reports a facial approach to solve this problem via the synthesis of a novel bifunctional polymer using inexpensive materials and easy methods. In this way, at the first step, heterogeneous poly (styrene sulfonic acid‐n‐vinylimidazole) containing pentaerythritol tetra‐(3‐mercaptopropionate) (PETMP) and trimethylolpropane trimethacrylate (TMPTMA) cross‐linkers were synthesized in the pores of a mesoporous silica structure using click reaction as a novel bifunctional acid–base catalyst. After that, Ni‐Pd nanoparticles supported on poly (styrenesulfonic acid‐n‐vinylimidazole)/KIT‐6 as a novel trifunctional heterogeneous acid–base‐metal catalyst was prepared. The prepared catalysts were characterized by various techniques like FT‐IR, TGA, ICP‐AES, DRS‐UV, TEM, FE‐SEM, EDS‐Mapping, and XRD. The synthesized catalysts were efficiently used as bifunctional/trifunctional catalysts for one‐pot, deacetalization‐Knoevenagel condensation and one‐pot, three‐step and a sequential reaction containing deacetalization‐Knoevenagel condensation‐reduction reaction. It is important to note that the synthesized catalyst showing high chemo‐selectivity for the reduction of nitro group, alkenyl double bond and ester group in the presence of nitrile. Moreover, it was found that the different nanoparticles including Ni, Pd, and alloyed Ni‐Pd showing different chemo‐selectivity and catalytic activity in the reaction.     

Microfluidic HPLC‐Chip devices with integral channels containing methylstyrenic‐based monolithic media

Polyimide HPLC‐Chip devices containing poly(methylstyrene‐bis‐p‐vinylphenyl)ethane (MS/BVPE) stationary phase within the device channels and with wall attachment were prepared by thermally initiated free radical polymerization. The microfluidic devices were coupled to both UV and MS detectors. The potential of the MS/BVPE monolith as an alternative separation media within chip devices was investigated by side‐by‐side comparisons to particulate media within commercial devices. The chromatographic behavior of this stationary phase was comparable to particulate media for separations of proteins as the average peak width at half‐height was equal (6.2 s) for a separation within 8 min under gradient elution conditions. The ability to control the porosity characteristics of the MS/BVPE monolith with changes in polymerization time also extended its utility into small analyte (< 500 Da) applications, although more optimization is needed to match conventional RP media for these applications. The good mechanical stability of the MS/BVPE monolith within the microdevices enabled excellent run‐to‐run repeatability (%RSD retention time (? 0.16) and chip‐to‐chip reproducibility (%RSD retention time (1.4). The use of this material within enrichment channels also shows its potential value in more complex work flows.     

Selective Pre-concentration and Solid Phase Extraction of Mercury（Ⅱ） from Natural Water by Silica Gel-loaded （E）-N-（1-Thien-2＇-ylethylidene）-1,2-phenylenediamine Phase

Silica gel-loaded （E）-N-（1-thien-2＇-ylethylidene）-1,2-phenylenediamine （TEPDA） phase was synthesized based on physical adsorption approaches. The stability of a chemically modified TEPDA especially in concentrated hydrochloric acid that was then used as a recycling and preconcentration reagent allowed the further uses of silica gel-loaded immobilized TEPDA phase. The application of this silica gel-loaded phase to sorption of a series of metal ions was performed by using different controlling factors such as the pH of the metal ion solution and the equilibration shaking time by the static technique. This difference was interpreted on the basis of selectivity incorporated in these sulfur containing silica gel-loaded TEPDA phases. Hg（Ⅱ） was found to exhibit the highest affinity towards extraction by these silica gel-loaded TEPDA phases. The pronounced selectivity was also confirmed by the determined distribution coefficients （Kd） of all the metal ions, showing the highest value reported for mercury（Ⅱ） extraction by the silica gel immobilized TEPDA phase. The potential applications of the silica gel immobilized TEPDA phase to selective extraction of mercury（Ⅱ） from aqueous solution were successfully accomplished and preconcentration of low concentration of Hg（Ⅱ） （30 pg·mL^-1） from natural tap water with a preconcentration factor of 200 for Hg（Ⅱ） off-line analysis was conducted by cold vapor atomic absorption analysis.