Synthesis of Isomeric Dimers of Deoxycholic Acid Derivatives Linked by 1,2,3-Triazole

Steroidal propargylic ester 6 and the propiolic ester 7 were prepared in a few steps from the deoxycholic acid. The Huisgen cycloaddition reaction of alkynes 6 and 7 as dipolarophiles with a 1,3-dipolar compound, the azide 5, afforded the dimeric compounds 8 and 9, respectively, in good yield. The dimers of deoxycholic acid derivatives linked by 1,4-disubstituted 1,2,3-triazole were characterized by spectroscopic methods.     

含三唑结构的新型稠合三环2(5H)-呋喃酮衍生物的合成

利用系列含烯二炔结构的2(5H)-呋喃酮衍生物与叠氮化钠发生串联的成环反应, 在优化的反应条件下, 即反应溶剂为DMF、反应时间48 h、反应温度30 ℃时、NaN₃为1.5 equiv., 以中等产率(42%～62%)合成了系列新型的稠合三环2(5H)-呋喃酮衍生物, 其可以进一步高产率地(94%～96%)衍生为吡啶稠合的2(5H)-呋喃酮化合物. 所有新化合物的结构用IR, ¹H NMR, ¹³C NMR, MS, 元素分析等方法进行了表征. 该串联反应合成途径简捷、反应条件温和, 无需添加催化剂, 可为具有含三唑结构的稠杂环化合物合成提供简便的途径.     

TBHP/AIBN-Mediated Synthesis of 2-Amino-thioazoles from Active Methylene Ketones and Thiourea under Metal-free Conditions

A new oxidative system of tert-butyl hydroperoxide (TBHP)/azodiisobutyronitrile (AIBN) has been used for the first time for a convenient, metal-free synthesis of substituted 2-aminothioazoles from active methylene ketone derivatives and thiourea. The reaction is postulated to proceed via an oxidative cyclization initiated by a radical process and followed by a condensation reaction.     

Design,Synthesis, Antimicrobial,and Antioxidant Activity of Dimers of Chromene Containing 1,2,3-Triazole Derivatives Bearing an Alkyl Spacer

A new series of chromene based 1,2,3-triazole derivatives has been synthesized by incorporating biologically active heterocyclic rings containing chromene and triazole moieties in one molecular structure. All newly synthesized compounds are characterized by ¹H and ¹³C NMR, mass, and IR spectra. The title compounds are tested for their activity against different bacterial and fungal strains, and antioxidant activity. Several compounds are determined to be potent antimicrobial and antioxidant agents.

     

KF/K2CO3/Al2O3催化合成香豆素

以Al2O3负载KF/K2CO3催化合成香豆素,水杨醛100 mmol,n(水杨醛)∶n(乙酸酐)∶n(KF/K2CO3/Al2O3)=1.0∶3.0∶0.3,于165℃反应2 h,香豆素产率高达89.8%。     

含1,2,3-三氮唑基团的新型四氧杂杯[2]芳烃[2]嘧啶衍生物的合成与抗肿瘤活性研究

以4-氯-2-甲硫基-6-丙炔氧基嘧啶为原料,依次经Williamson醚合成、氧化和聚合反应制得新型四氧杂杯[2]芳烃[2]嘧啶母体(4),并通过点击化学反应合成了4个结构新颖的含1,2,3-三氮唑基团的四氧杂杯[2]芳烃[2]嘧啶衍生物(5a^5d),其结构经1H MNR,13C MNR和HR-MS(ESI)表征。采用MTT法研究了5a^5d对人宫颈癌细胞(Hela),人乳腺癌细胞(MCF-7),人肝癌细胞(HepG2)和人肺癌细胞(A549)的体外抗肿瘤活性。结果表明:化合物5a对MCF-7具有明显的抑制活性,在50μM浓度下抑制率可达82%,优于阳性对照药5-氟尿嘧啶。     

Hydrogenation of CO2 to Formic Acid with a Highly Active Ruthenium Acriphos Complex in DMSO and DMSO/Water

The novel [Ru(Acriphos)(PPh₃)(Cl)(PhCO₂)] [ 1 ; Acriphos=4,5‐bis(diphenylphosphino)acridine] is an excellent precatalyst for the hydrogenation of CO₂ to give formic acid in dimethyl sulfoxide (DMSO) and DMSO/H₂O without the need for amine bases as co‐reagents. Turnover numbers (TONs) of up to 4200 and turnover frequencies (TOFs) of up to 260 h^?1 were achieved, thus rendering 1 one of the most active catalysts for CO₂ hydrogenations under additive‐free conditions reported to date. The thermodynamic stabilization of the reaction product by the reaction medium, through hydrogen bonds between formic acid and clusters of solvent or water, were rationalized by DFT calculations. The relatively low final concentration of formic acid obtained experimentally under catalytic conditions (0.33 mol L^?1) was shown to be limited by product‐dependent catalyst inhibition rather than thermodynamic limits, and could be overcome by addition of small amounts of acetate buffer, thus leading to a maximum concentration of free formic acid of 1.27 mol L^?1, which corresponds to optimized values of TON=16×10³ and TOF_avg≈10³ h^?1.     

水介质中无催化剂下醛酮与活泼亚甲基化合物的缩合反应

报道了水相中无催化剂下各种羰基化合物与活泼亚甲基化合物的Knoevenagel缩合反应. 芳香醛与活泼亚甲基化合物如丙二腈、氰基乙酸乙酯、氰基乙酰胺的缩合在室温下即能顺利进行, 获得了很高的收率; 而对于杂环芳醛、α,β-不饱和的醛以及脂肪醛与活泼亚甲基化合物的缩合, 需在50～65 ℃下进行, 也取得了很高的收率; 对于脂肪酮、芳香酮以及二元醛与丙二腈的缩合在75～85 ℃下也能顺利地进行, 获得中等以上的收率. 反应简单、高效而且对环境友好.     

2-Azido-1,3,4-thiadiazoles, 2-Azido-1,3-thiazoles,and Aryl Azides in the Synthesis of 1,2,3-Triazole-4-carboxylic Acids and Their Derivatives

Diazotization of 2-amino-1,3,4-thiadiazoles gave 1,3,4-thiadiazole-2-diazonium sulfates which were converted to 2-azido-1,3,4-thiadiazoles. The latter reacted with ethyl acetoacetate in the presence of sodium methoxide in methanol to produce 1-(5-R¹-1,3,4-thiadiazol-2-yl)-5-R²-1H-1,2,3-triazole-4-carboxylic acid derivatives. The reactions of 2-azido-5-methyl-1,3,4-thiadiazole and 2-azido-1,3-thiazole with ethyl 3-(1,3-benzodioxol-5-yl)-3-oxopropanoate led to the formation of 1,2,3-triazole ring under milder conditions (K₂CO₃, DMSO). Various 1,2,3-triazole-4-carboxylic acid derivatives were synthesized.     

Knoevenagel Condensation of Aromatic Aldehydes with Active Methylene Compounds using a Catalytic Amount of Iodine and K2CO3 at Room Temperature

A convenient method for Knoevenagel condensation of aromatic aldehydes with malononitrile or ethyl cyanoacetate has been developed using the inexpensive and environmentally friendly reagent I₂/K₂CO₃ at room temperature. The method is mild and simple with good to high product yields.     

Asymmetric Synthesis of Tetrahydroisoquinoline Derivatives through 1,3-Dipolar Cycloaddition of C,N-Cyclic Azomethine Imines with Allyl Alkyl Ketones

A [3 + 2] 1,3-Dipolar cycloaddition of C,N-cyclic azomethine imines with allyl alkyl ketones has been achieved. The reaction proceeds under mild conditions and tolerates a wide range of functional groups. An array of tetrahydroisoquinoline derivatives is generally constructed with good diastereoselectivities and enantioselectivities (up to >25:1 dr, >95% ee). Moreover, the absolute configuration of the product was previously determined by using the quantum electronic circular dichroism calculation and ECD spectrum method.     

K2CO3-Na2CO3-Li2CO3-H2O四元体系288K的相平衡

水盐体系;碳酸盐;溶解度;盐湖卤水;K2CO3-Na2CO3-Li2CO3-H2O四元体系288K的相平衡     

Convenient Synthesis of Terminal Alkynes from anti‐3‐Aryl‐2,3‐dibromopropanoic Acids Using a K2CO3/DMSO System

A convenient, efficient, and generally applicable method was developed for the synthesis of terminal alkynes from anti‐3‐aryl‐2,3‐dibromopropanoic acids in the presence of DMSO and K₂CO₃.     

Reaction of Anthranilonitrile with Some Active Methylene Reagents: Synthesis of Some New Quinoline and Quinazoline Derivatives

Anthranilonitrile (1) reacts with ethyl cyanoacetate and its dimer, malononitrile, cyanothioacetamide and N‐arylidene cyanoacetohydrazides 12a–c to afford pyrano[2,3‐b]quinoline 5, cyanomethyl‐quinazoline 10, pyrazolo[2,3‐a]quinazoline 12 and triazolo[4,3‐a]‐quinoline derivatives 16a–c, respectively. Structures and conceivable mechanisms are discussed.     

Synthesis of glycerol carbonate from glycerol and dimethyl carbonate catalyzed by K2CO3/MgO

A series of M/MgO (M?=?CaO, KNO₃, KOH, K₂CO₃) catalysts were prepared by a dry impregnation method and used for synthesis of glycerol carbonate from glycerol and dimethyl carbonate. It was found that K₂CO₃/MgO was the most efficient catalyst, with a glycerol carbonate yield of approximately 99% under the conditions: DMC/glycerol molar ratio 2.5:1, catalyst/raw material weight ratio 1%, reaction time 2?h, and reaction temperature 80?°C. FTIR, BET, TEM, and XRD were used for characterization of the catalyst and showed that the active sites seemed to be K₂O formed on the K₂CO₃/MgO catalyst. Finally, a recycling experiment showed that the catalyst was relatively stable and could be reused up to four times, at least, by regeneration.     

Montmorillonite K10/ZnCl2 Catalyzed Alkyl Disulfide Substitution Reactions: Preparation of Thiomethyl Derivatives for the Synthesis of Organic Conducting Materials

Experiments are described detailing a method for the direct introduction of thiomethyl groups into activated benzenes, thiophene and benzo[b]thiophene using an activated mesoporous clay to promote thiomethyl substitution. Elaboration of 2,3-dithiomethylbenzo[b]thiophene, a product of the clay-catalyzed reaction of benzo[b]thiophene with dimethyl disulfide, to a tetrathiafulvalene derivative is described.     

2-取代-4-芳基-2H-1,2,3-三唑类化合物的合成及杀菌活性

1,2,3-三唑化合物具有广泛的生物活性,为了发现具有杀菌活性的新型化合物分子结构,以芳醛、硝基甲烷及叠氮化钠为起始原料,合成了11个2-取代-4-芳基-2H-1,2,3-三唑类系列化合物,目标物的收率为51%~91%。核磁共振谱、质谱和元素分析等技术手段对目标化合物的结构经进行了表征。结果表明,在25 mg/L的测试质量浓度下,大部分化合物对小麦赤霉病菌及辣椒疫霉病菌显示出初步的抑菌活性,其中,化合物3a对小麦赤霉病菌的抑制率为80. 4%,化合物3b对黄瓜灰霉病菌为78. 2%,化合物3b及3h对油菜菌核病菌的抑制率分别70. 3%和75. 9%。     

Enhancement of CO2 sorption uptake on hydrotalcite by impregnation with K2CO3

The awareness of symptoms of global warming and its seriousness urges the development of technologies to reduce greenhouse gas emissions. Carbon dioxide (CO(2)) is a representative greenhouse gas, and numerous methods to capture and storage CO(2) have been considered. Recently, the technology to remove high-temperature CO(2) by sorption has received lots of attention. In this study, hydrotalcite, which has been known to have CO(2) sorption capability at high temperature, was impregnated with K(2)CO(3) to enhance CO(2) sorption uptake, and the mechanism of CO(2) sorption enhancement on K(2)CO(3)-promoted hydrotalcite was investigated. Thermogravimetric analysis was used to measure equilibrium CO(2) sorption uptake and to estimate CO(2) sorption kinetics. The analyses based on N(2) gas physisorption, X-ray diffractometry, Fourier transform infrared spectrometry, Raman spectrometry, transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy were carried out to elucidate the characteristics of sorbents and the mechanism of enhanced CO(2) sorption. The equilibrium CO(2) sorption uptake on hydrotalcite could be increased up to 10 times by impregnation with K(2)CO(3), and there was an optimal amount of K(2)CO(3) for a maximum equilibrium CO(2) sorption uptake. In the K(2)CO(3)-promoted hydrotalcite, K(2)CO(3) was incorporated without changing the structure of hydrotalcite and it was thermally stabilized, resulting in the enhanced equilibrium CO(2) sorption uptake and fast CO(2) sorption kinetics.     

Synthesis of 2-Aminochromene Derivatives Catalyzed by KF／Al2O3

A series of 2-aminochromene derivatives including 2-amino-ben-zo[ h ] chromene, 2-amino-benzo [ f ] chromene and 2-amino-pyrano [3,2-h ]quinolin derivatives was synthesized from aryl-aldehyde, malononitrile or ethyl cyanoacetate and 1-naphthol or 2-naphthoi or 8-hydroxyquinoline in refluxing ethyl alcohol cat-alyzed by KF-Al2O3. The structures were confirmed by X-ray analysis.