Ultrasound promoted one-pot synthesis of 3-aza-6,10-diaryl-2-oxa-spiro[4.5]decane-1,4,8-trione

One-pot synthesis of 3-aza-6,10-diaryl-2-oxa-spiro[4.5]decane-1,4,8-trione from 1,5-diaryl-1,4-pentadien-3-one can be carried out in good yields at 50 °C under ultrasound irradiation. This method provided several advantages such as simple work-up procedure, shorter reaction time and higher yield.     

Synthesis of 1,5-dinitroaryl-1,4-pentadien-3-ones under ultrasound irradiation

1,5-Dinitroaryl-1,4-pentadien-3-ones were synthesized with ultrasound irradiation in the presence of K(2)CO(3) as catalyst. The reaction mechanism and the factors influencing the product were also discussed. The present procedure is more convenient with shorter reaction time and higher yields compared with conventional methods.     

Synthesis of 1,1-disubstituted-2,6-diarylcyclohexane-4-ones catalyzed by KF/basic Al2O3 under ultrasound

1,1-Disubstituted-2,6-diarylcyclohexane-4-ones have been synthesized via double Michael addition of 1,5-diaryl-1,4-pentadien-3-one with various active methylene compounds such as dimethyl malonate, diethyl malonate, methyl cyanoacetate and ethyl cyanoacetate catalyzed by KF/basic alumina under ultrasound irradiation to give good yields within a short time.     

One-pot three-component synthesis of 3-hydroxy-5,5-dimethyl-2-[phenyl(phenylthio)methyl]cyclohex-2-enone derivatives under ultrasound

3-Hydroxy-5,5-dimethyl-2-[phenyl(phenylthio)methyl]cyclohex-2-enone is synthesized via one-pot three-component reactions of aromatic aldehyde, substituted thiophenol and 5,5-dimethyl-1,3-cyclohexanedione catalyzed by p-dodecylbenzene sulfonic acid (DBSA) under ultrasound. Under ultrasound irradiation the yields are much higher (sometimes substantially, by almost double) and the reaction time decreases substantially, the reaction conditions are milder. This method provides several advantages such as environment friendliness, high yields and simple work-up procedure and the protocol provides a novel alternative for the synthesis of thioether.     

Synthesis of new 1,5-diaryl-3-(arylamino)-1H-pyrrol-2(5H)-ones under catalyst-free and solvent-free conditions

Several new 1,5-diaryl-3-(arylamino)-1H-pyrrol-2(5H)-ones were synthesized via the three-component condensation reaction of aldehydes, aromatic amines, and ethyl pyruvate under catalyst-free and solvent-free conditions. Also, 5-(4-hydroxyl-3-nitrophenyl)-1-(4-methoxy-phenyl)-3-(4-methoxyphenylamino)-1,5-dihydro-pyrrol-2-one was synthesized using oxime instead of aldehyde. The eco-friendly, simple procedure, green procedure, catalyst-free and solvent-free conditions, short reaction times, and high yields of the products are the advantages of this method.     

A novel and convenient synthesis of 4-hydroxy-6-methyl-3-(1-(phenylimino) ethyl)-2H-pyran-2-one derivatives under ultrasound irradiation

A facile, efficient and environment-friendly protocol for the synthesis of 4-hydroxy-6-methyl-3-(1-(phenylimino)ethyl)-2H-pyran-2-one derivatives has been developed by the convenient ultrasound-mediated condensation of amine with dehydroacetic acid. This method provides several advantages over current reaction methodologies including a simple work-up procedure, shorter reaction times and higher yields.     

A One-Pot Entry to a Novel 3-H-benzo[d]pyrazolo[1,5-b]isothiazole Ring System

Summary The phosphorus ylide obtained from the reaction between 2-aminobenzo[d]isothiazol-3-one and dimethyl acetylenedicarboxylate in the presence of triphenylphosphine undergoes a smooth intramolecular Wittig-type reaction to produce, in a one-pot reaction, 3-H-benzo[d]pyrazolo[1,5-b]isothiazole-2,3a-dicarboxylic acid dimethyl ester, a novel functionalized heterocyclic compound.     

An unexpected tetracyclic product isolated during the synthesis of biscoumarins catalyzed by [MIM(CH2)4SO3H][HSO4]: Characterization and X-ray crystal structure of 7-(2-hydroxy-4-oxo-4H-chromen-3-yl)-6H,7H-chromeno[4,3-b]chromen-6-one

Under solvent-free conditions and in the presence of 3-methyl-1-(4-sulfonic acid)butylimidazolium hydrogen sulfate [MIM(CH₂)₄SO₃H][HSO₄], a Brønsted acidic ionic liquid, the reaction of aromatic aldehydes with 4-hydroxycoumarin has been investigated. A wide range of aromatic aldehydes easily undergoes condensation with 4-hydroxycoumarin to afford biscoumarins with good purity in excellent yields. However, reaction of 2-hydroxybenzaldehyde with 4-hydroxycoumarin gave, not the corresponding biscoumarin, but a tetracyclic compound, 7-(2-hydroxy-4-oxo-4H-chromen-3-yl)-6H,7H-chromeno[4,3-b]chromen-6-one, in high yield.     

Ethylene glycol promoted catalyst-free pseudo three-component green synthesis of bis(coumarin)s and bis(3-methyl-1-phenyl-1<Emphasis Type="Italic">H</Emphasis>-pyrazol-5-ol)s

An ethylene glycol promoted catalyst-free practically efficient and sustainable approach has been developed for the synthesis of several benzylidene-bis-(4-hydroxycoumarin)s and 4,\(4^{\prime }\)-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s by the pseudo three-component reaction of an aldehyde with 4-hydroxycoumarin and 3-methyl-1-phenylpyrazol-5-one, respectively. Inexpensive, non-toxic, and easily available ethylene glycol used as the reaction solvent and promoter renders an efficient protocol in terms of catalyst-free reaction conditions, short reaction time, high yield, practical utility, and green approach.     

1,5-二硝基-2,4-二硝亚胺基-六氢化-1,3,5-三嗪的合成与表征

以硝基胍和甲醛为原料,在盐酸中反应得到亚甲基二硝基胍,经HNO₃/Ac₂O硝化得到1,5-二硝基-2,4-二硝亚胺基-六氢化-1,3,5-三嗪,产率为71.4%,并采用核磁共振光谱、红外光谱、质谱以及元素分析等进行了结构表征,研究了硝化剂、反应温度和反应时间等条件对硝化反应的影响。     

Efficient sonochemical synthesis of novel 3,5-diaryl-4,5-dihydro-1H-pyrazole-1-carboximidamides

An ultrasound-assisted preparation of a series of novel 3,5-diaryl-4,5-dihydro-1H-pyrazole-1-carboximidamides that proceeds via the efficient reaction of chalcones with aminoguanidine hydrochloride under clean conditions is described.     

Solid-phase synthesis of tetrahydro-1,4-benzodiazepin-2-one derivatives

An efficient method for solid-phase construction of tetrahydro-1,4-benzodiazepin-2-one scaffold is described. Polymer-bound 4-(bromomethyl)-3-nitrobenzoic acid was reacted with alpha-amino acid methyl esters, followed by nitro group reduction and hydrolysis. Subsequent intramolecular cyclization and alkylation at N(4) afforded the structurally diverse products in high yields and excellent purities.     

A mild and efficient method for the synthesis of a new class of furo[3,2-c]chromenes in aqueous media

An efficient synthesis of 2-hydroxy-3-[2-oxo-2-phenylethylidene]-2-phenyl-2, 3-dihydro-4 H-furo[3, 2-c]chromene-4(2H)-one is described. This involves the reaction between dibenzoylacetylene and 4-hydroxycoumarine in the presence of NaH (10 mol %) in nearly quantitative yield. Treatment of this heterocyclic system with trimethyl chlorosilane in CHCl₃ leads quantitatively to 4-oxo-3-[2-oxo-2-phenylethylidene]-2-phenyl-3H, 4H-furo[3,2-c]chromene-1-ium chloride. Direct addition of nucleophiles, such as alcohols, amines or trialkyl phosphites to this salt in water as the solvent produces functionalized 2-phenyl-4H-furo[3,2-c] chromen derivatives in excellent yields.     

Ultrasound assisted green synthesis of bis(indol-3-yl)methanes catalyzed by 1-hexenesulphonic acid sodium salt

1-Hexenesulphonic acid sodium salt as catalyst for green synthesis of bis(indol-3-yl)methanes was described. The reaction of indole with various aldehydes in water using ultrasound irradiation at ambient temperature for appropriate time using 1-hexenesulphonic acid sodium salt furnish the desired product in good to excellent yield. Utilization of aqueous medium, simple reaction conditions, isolation, and purification makes this manipulation very interesting from an economic and environmental perspective.     

二维层状聚苯胺及其TiO2复合物的制备与光谱学研究

聚苯胺(PANI)是一种具有优良光、电、磁等性能的导电高分子,而TiO2/聚苯胺复合物是结合了聚苯胺和TiO2无机粒子优点的产品。在表面活性剂十二烷基苯磺酸(DBSA)和水形成的微乳液体系中,利用过硫酸铵(APS)将苯胺直接聚合成具有二维层状结构的聚苯胺,进而通过采用钛酸正丁酯水解与苯胺聚合同时进行的策略合成了层状TiO2/聚苯胺复合物。通过扫描电镜图片(SEM)发现二维层状结构的聚苯胺是由大量聚苯胺薄片堆积而成。X射线衍射(XRD)分析表明聚苯胺及其复合物的层间距均为3.4nm,说明这种层状结构极有可能是由DBSA通过协同排列成较为规整的双层分子支撑而成的。傅里叶变换红外谱图(FTIR)说明聚苯胺分子链主要是由苯环和醌环结构组成,拉曼光谱(Raman)和X射线光电子能谱图(XPS)则证明钛酸正丁酯在微乳液体系中水解形成的TiO2具有金红石型结构。紫外可见吸收光谱图(UV-Vis)说明引入无机物TiO2会直接改变导电聚合物分子链的电子跃迁行为。     

Synthesis, crystal growth and characterization of 1,5-diphenylpenta-1,4-dien-3-one: An organic crystal

1,5-Diphenylpenta-1,4-dien-3-one ( dibenzalacetone, DBA) was synthesized by a base-catalyzed aldol condensation reaction between benzaldehyde and acetone. High quality single crystals have been grown by the slow evaporation of ethanol solution and the crystal belongs to monoclinic system with centrosymmetric space group C 2/c. The DBA crystals are transparent in the entire visible region and have a lower optical cutoff at ∼440 nm. It is stable up to 119 °C and has a good chemical stability. The high resolution X-ray diffraction curve (DC) indicates that the specimen is free from structural grain boundaries. Molecular packing leads to a centrosymmetric arrangement resulting in zero second harmonic generation (SHG; χ⁽²⁾=0) efficiency.     

Benign methodology and improved synthesis of 5-(2-chloroquinolin-3-yl)-3-phenyl-4,5-dihydroisoxazoline using acetic acid aqueous solution under ultrasound irradiation

In the present paper, we have executed the synthesis of substituted 5-(2-chloroquinolin-3-yl)-3-phenyl-4,5-dihydroisoxazolines via the reactions of substituted 3-(2-chloroquinolin-3-yl)-1-phenylprop-2-en-1-ones with hydroxylamine hydrochloride and sodium acetate in aqueous acetic acid solution in 72-90% yields at room temperature under ultrasound irradiation. This method provides several advantages such as operational simplicity, higher yield, safety and environment friendly protocol. The resulting substituted isoxazolines were characterized on the basis of (1)H NMR, (13)C NMR, IR, elemental analysis, and mass spectral data.     

Highly efficient synthesis of quinoxaline derivatives from 1,2-benzenediamine and $$\alpha $$-aminoxylated 1,3-dicarbonyl compounds

Simple and efficient synthetic procedures for the preparation of quinoxaline, pyrazine, pyridopyrazine, and benzoxazin-2-one derivatives were developed. The one-pot cascade process involves the acidic elimination of \(\alpha \)-aminoxylated dicarbonyl compounds to generate 1,2,3-tricarbonyl compounds and subsequent condensation with 1,4-N,N or -N,O dinucleophiles to afford quinoxaline, pyrazine, pyridopyrazine, and benzoxazin-2-one scaffolds. All the proposed processes do not need extra catalysts, dry solvents, or harsh reaction conditions.     

Ultrasound accelerated esterification of palmitic acid with vitamin C

The esterification of palmitic acid with vitamin C in the presence of concentrated sulfuric acid as the solvent and catalyst by means of 25 kHz ultrasonic irradiation to obtain l-ascorbyl 6-palmitate is studied. By using ultrasound the dissolution rate of the reactants can be accelerated greatly, the reaction time of esterification can be reduced from 36 to 2h, and better yield (90-93%) of ester can be given by using 95% concentrated sulfuric acid as the solvent and catalyst, contrast to the yield of 75-85% by using 99% concentrated sulfuric acid without ultrasound. The influence of reaction conditions and ultrasonic parameters to the yield of ascorbyl palmitate are reported.     

Scaffold-directed and traceless synthesis of tricyclic quinoxalinone imidazoles under microwave irradiation

Traceless synthesis of 2-aminoimidazoquinoxalinones has been performed on soluble polymer support under open-vessel microwave dielectric heating. The reaction progression is monitored directly by the conventional proton NMR which indicated no release of the substrate from the support. Fmoc-deprotected amino acid polymer conjugates react with 1,5-difluoro-2,4-dinitro benzene to yield polymer bound dinitro fluoro amines, which are further substituted by various primary amines to yield PEG-immobilized dinitrodiamines. Simultaneous reduction of aromatic meta-dinitro group leads to the traceless release of 2-quinoxalinones, followed by N-hetero cyclization with various isothiocyanates in the presence of mercury(II)chloride to furnish 2-aminoimidazoquinolinone rings with three points of diversity at rapid pace.