Oxone‐Mediated Oxidative 3‐Arylthio Substitution of Indoles

Oxone‐mediated oxidative 3‐arylthio substitution of indoles with benzenethiols in methanol has been succeeded, giving 3‐arylthioindoles. Indoles bearing a 2‐methyl group particularly exhibited higher activities toward 3‐arylthio substitutions. 3‐(2′‐Pyridylthio)indoles used as selective COX‐2 inhibitors were prepared in good to excellent yields.     

Practical Synthesis of (S)‐(+)‐3‐Octanol by Lipase‐Catalyzed Enantioselective Acetylation

(S)‐(+)‐3‐Octanol (S)‐1 was prepared in high enantiomeric excess through catalyzed acetylation of racemic alcohol 1 by using lipase from Candida antarctica (Chirazyme L‐2) in the presence of vinyl acetate in toluene at 30°C. The pure (S)‐1 was obtained in 73% isolated yield with 62% conversion. Moreover, acetate (R)‐2 was converted to (S)‐1 via mesylation and followed by hydrolysis using sodium bicarbonate solution in 44% yield.     

Catalytic Oxidative Cyclocondensation of o‐Aminophenols to 2‐Amino‐3H‐phenoxazin‐3‐ones

The catalytic oxidative cyclocondensation of the o‐aminophenols 1a–f was investigated. The oxidants used were air/laccase, H₂O₂/horseradish peroxidase, H₂O₂/ebselen (3), and TBHP/diphenyl diselenide 4. The products obtained were 2‐amino‐3H‐phenoxazin‐3‐one—questiomycin A, its derivative 2b, and cinnabarinic acid and actinocin (2c,d). Substrates with methyl groups at 4 and 5 positions of benzene ring were converted to different dihydrophenoxazinones 2g,h. Compounds having chlorine atoms at the same positions underwent oxidation to planar phenoxa-zinones 2e,f with elimination of one hydrochloride molecule.     

t‐Butyl Hydroperoxide Oxidative Dealkylation of Hydroquinone Ethers to 1,4‐Quinones

Various organoselenium compounds (diselenides, benzisoselenazol‐3(2H)‐ones, and 1,3,2‐thiaselenazolones) are effective catalysts for oxidative dealkylation of hydroquinone ethers with t‐butyl hydroperoxide to 1,4‐quinones. The reactions is most efficient when t‐butyl hydroperoxide in the presence of poly(bis‐1,2‐phenyl) diselenide is used as an oxidizing agent. In this way 1,4‐benzo and 1,4‐naphthoquinones are produced in good to high yields.     

Regioselective Acetylation of β-Cyclodextrin

One-stage methods of synthesis of water-soluble -cyclodextrins selectively acetylated by primary or secondary hydroxy groups have been found, that make use of acetyl chloride and hydrogen chloride acceptors of different nature.     

Oxidative Cleavage of Oximes with Silica‐Gel‐Supported Chromic Acid in Nonaqueous Media

A simple procedure for a clean and high‐yielding oxidative deoximation of benzaldoximes and ketoximes using a silica‐gel‐supported chromic acid reagent has been developed. This solid‐supported reagent allows us to carry out this reaction in nonaqueous dichloromethane reaction media.     

Oxidative Coupling of Phenols by2，2，6，6－Tetramethyl－4－methoxypiperidine OxoammoniumChloride

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Voltammetric Determination of Bisphenol A Using an Acetylene Black‐Dihexadecyl Hydrogen Phosphate Composite Film‐Modified Electrode

Abstract

Herein, acetylene black (AB) was easily dispersed into water in the presence of dihexadecyl hydrogen phosphate (DHP), resulting in a stable and homogeneous AB‐DHP suspension. Then, an AB‐DHP composite film coated glassy carbon electrode (GCE) was constructed after evaporation of water. The electrochemical behavior of bisphenol A was investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and differential pulse voltammetry (DPV). Compared with the unmodified GCE, the AB‐DHP film‐modified GCE not only significantly enhances the oxidation peak current of bisphenol A but also lowers the oxidation overpotential, suggesting that AB‐DHP film‐modified GCE has great potential in sensitive determination of bisphenol A. Based on this, a sensitive and simple electrochemical method was developed after optimization of the experimental parameters such as supporting electrolyte, the amount of AB‐DHP, scan rate, and accumulation time. The linearity is over the range form 2.0×10^?8 to 5.0×10^?6 mol l^?1, and the detection limit is 6.0×10^?9 mol l^?1. Finally, this method was successfully employed to determine bisphenol A in waste water samples.     

Hypervalent Iodine‐Mediated Synthesis of 1‐Aryl‐4‐methyl‐1,2,4‐triazolo[4,3‐a]quinoxalines by Oxidative Cyclization of Arene Carbaldehyde‐3‐methylquinoxalin‐2‐yl Hydrazones

Arene carbaldehyde‐3‐methylquinoxalin‐2‐yl hydrazones (2) obtained by the condensation of 2‐hydrazino‐3‐methylquinoxaline (1) with various aromatic aldehydes, on treatment with iodobenzene diacetate (IBD) in dichloromethane, undergo oxidative cyclization to exclusively afford 1‐aryl‐4‐methyl‐1,2,4‐triazolo[4,3‐a]quinoxalines (5) in excellent yield.     

Convenient,Cost‐Effective,and Mild Method for the N‐Acetylation of Anilines and Secondary Amines

Abstract

An efficient, cost‐effective, and mild method for the N‐acetylation of anilines and secondary amines with ammonium acetate in acetic acid media at reflux temperature in good yield is described.     

ZnBr2‐Catalyzed Efficient Oxidative Homo Coupling of Aryl Magnesium Bromides

Oxidative homo coupling of various arylmagnesium bromides in the presence of ZnBr₂ gave the corresponding symmetrical biaryls in moderate to good yields at room temperature. An efficient method under mild conditions without the use of reoxidant is described.     

Acetylation of α- and β-cyclodextrines

Applying acetyl chloride and versatile bases and solvents per- and regioacetylated derivatives of α- and β-cyclodextrines were prepared. Conditions were established for performing regiodirected acetylation of the primary hydroxy groups of α- and β-cyclodextrines in the presence of free secondary hydroxy groups.     

Alternate Method for the Synthesis of N‐Alkyl/aralkyl‐2‐(α‐hydroxy Alkyl/aralkyl)benzimidazoles via Regiospecific Acetylation

Acetylation of 1H‐2‐(α‐hydroxyalkyl/aryl)benzimidazoles 2 with Ac₂O results in the regiospecific formation of O‐acetoxy derivative 3, which on alkylation with alkylating agents in nonaqueous media under phase‐transfer catalytic conditions affords N‐alkyl derivatives 4. The latter, on hydrolysis in an aqueous basic medium, results in the title compounds 5 in good yields in high purity. Alternatively, 5 can also be obtained by reduction of 1‐substituted‐2‐acetyl/benzoylbenzimidazoles 8 using NaBH₄.     

Regiospecific Acetylation of Substituted α,α′‐Benzylidenedimethanols with Vinyl Acetate using Porcine Pancreas Lipase

Acetylation of substituted α,α′‐benzylidenedimethanols with 10 equivalents of vinyl acetate in the presence of 50 w/w% of porcine pancreas lipase (PPL) type II regiospecifically proceeded to afford only the corresponding E‐monoacetates in excellent yields without Z‐monoacetates, diacetate, or the starting materials.     

Oxidative Cyclization of Aromatic Aldehyde N‐Acylhydrazones by bis(Trifluoroacetoxy)iodobenzene

Aromatic aldehyde N‐acylhydrazones were oxidized into 2,5‐disubstituted 1,3,4‐oxadiazoles with bis(trifluoroacetoxy)iodobenzene in CHCl₃ or DMSO at room temperature in good to excellent yields.     

Salt‐Induced Micellization of Pluronic F88 in Water

The effect of potassium chloride on the micellization of a poly(ethylene oxide)‐poly(propylene oxide)‐poly(ethylene oxide) (PEO‐PPO‐PEO) triblock copolymer (Pluronic F88: EO₁₀₃PO₃₉EO₁₀₃.) in water was studied by fluorescence, FTIR, ¹H NMR, dynamic light scattering, and dye solubilization. The critical micellization temperature (CMT) values of the copolymer decreased with an increase of KCl concentration while micellar core gets progressively dehydrated. The results reveal the leading role of salt‐water interaction in promoting the micellization of PEO‐PPO‐PEO copolymer by the addition of salt. No significant micellar growth was seen even at temperatures close to cloud point.     

Ultrasound‐Promoted Rapid Oxidative Cleavage of Oximes with NaBrO3/Ion Exchange Resin

The oxidative cleavage of oximes has been studied under solvent‐free ion exchange resin (IER) catalysis by sodium bromate using ultrasonic irradiation. Both aldoximes and keto‐oximes selectively converted to the corresponding carbonyl compounds in high yields within short times at room temperature.     

Polymerization of Bisphenol A Epoxy Resin with Polyethylene glycol

IntroduedonReCenUy,PEG/alkalisaltcomPlexeshavreceivedmoreattentionduetotheirpotentialaPpliboonsinsolideleCtrlytd'.:1.ItisreportedthatforPEGjalkalicomPlexes,thealkaliionstranSPOrtintheamorPhousdomainshaerthaninthecrystallindornains[3].TherefOre,thePEGlalkalicomplexeswithhighioncondudrityedbeot)tainediftheCryalltyOfPEGis~.HongFangMGetalhavereportedthatheepoxyresincouldbotheeq~tyofPEGintheirblendsI'1.ItcanbeepeedthatheinteraedonbetweCnPEGandopxyresininacoPOlyInerwillbecomeStrDnge…     

Adsorption of Bisphenol A by Cross-Linked β-Cyclodextrin Polymer

An insolubilized -cyclodextrin derivative(polyCD) was prepared by polymerizingcyclodextrin with epichlrohydrine. By stirring5 mg/ml of polyCD in 0.2 mM bisphenolA (BPA) solution at pH 7.0 for 2 h, more than98% of BPA was adsorbed on polyCD.The capacity of the adsorption was determinedto be 84 mg-BPA/g-polyCD, meaning 0.65mol-BPA/mol-CD (in polyCD). The effect of pHon the adsorption was studied and foundthat BPA was effectively adsorbed on polyCDat pH between pH 2.2–9.1, but the efficiencydecreased at pH 10.8, suggesting that it didnot adsorb the BPA anion. The polyCD did notadsorb aromatic amino acids, indicating thatBPA could selectively be removed from asolution containing amino acids.     

Synthesis,Characterization and Comparison of Properties of Novel Fluorinated Polyimides Derived from Bisphenol–A‐di(phthaleic anhydride)

Four new poly(etherimide)s have been synthesized by reaction with commercially available bisphenol‐A‐(diphthaleic anhydride) (BPADA) with four different kinds of diamines, namely 4,4′‐bis(p‐aminophenoxy‐3,3″‐trifluoromethyl) terphenyl,4,4′‐bis(3″‐trifluoromethyl‐p‐aminobiphenyl ether)biphenyl,2,6‐bis(3′‐trifluoromethyl‐p‐aminobiphenyl ether)pyridine, 2,5‐bis(3′‐trifluoromethyl‐p‐aminobiphenylether)thiopene. The poly(etherimide)s are named as 1a, 1b, 1c and 1d, respectively. The synthesized polyimides show good solubility in various organic solvents. The polyimide films had low water absorption of 0.19–0.30% and low dielectric constant of 2.79–3.1 at 1 MHz. These polyimides showed very high thermal stability with decomposition temperature (5% wt loss) up to 522°C in nitrogen. Transparent thin films of these polyimides exhibited tensile strength up to 97 MPa, a modulus of elasticity up to 1.56 GPa and elongation at break up to 20%.