Chemoselective Bromodecarboxylation of α-Carboxy- α-cinnamoyl Ketene Cyclic Dithioacetals

α-Oxoketene dithioacetals（ compound 1 ） are versatile synthons for organic synthesis due to their specially structural characteristic, that is, the masked ketene is conjugated with the convertible carbonyl in their molecules. Although there have been numerous reports covering the reactions in which they have been taken as 1,3-electrophiles, the reaction at the α-carbon atom of α-oxoketene dithioacetals has seldom been investigated. Junjappa and co-workers found the α- bromination of compound 2 in the presence of NBS led to α-aroyl-α-bromo ketenedithioacetals. However, the flexibility of the functional groups at the α-carbon atom of compound 2 are still limited.     

四种α,α'-二氧代烯酮环二硫代缩酮类化合物的电化学性质及光谱研究

本文应用循环伏安法(CV)、UV-Vis、交流阻抗(EIS)和X射线光电子能谱(XPS)等技术研究了4种α-羰基二硫缩烯酮化合物在有机溶剂中的电化学和光谱性质及其在金电极上的自组装膜行为, 根据循环伏安数据计算了此类化合物在DMSO溶液中的扩散系数和电极反应速率常数.     

Iron Chloride Hexahydrate-catalyzed Friedel-Crafts Akylation of Cyclic Ketene Dithioacetals with Alcohols

A cost-effective and environmentally compliance FeCl₃·6H₂O catalyzed Friedel-Crafts alkylation of cyclic ketene dithioacetals with alcohols was developed. The reaction was efficient in the presence of catalyst loading as low as 5%(molar fraction) in CH₂Cl₂ solvent at room temperature or under reflux conditions. A wide range of alkylated ketene dithioacetals were synthesized in excellent yields.     

Direct Synthesis of Unsymmetrical Dithioacetals

Dithioacetals are a frequently used motif in synthetic organic chemistry and have recently seen increasing attention as structural motif in promising antiviral agents against plant pathogens. Most existing reports, however, only discuss symmetrical dithioacetals. Examples of mixed dithioacetals are scarce and no general method for the selective synthesis of these compounds exists. Herein, a synthetically simple general one-step protocol was developed for the synthesis of a broad range of unsymmetrical dithioacetals consisting of one aromatic and one aliphatic thiol moiety from the corresponding aldehyde/thiol mixture. The mixed S,S-acetals were obtained in high yields, and a great variety of functional groups was tolerated. Kinetic control enabled an excellent selectivity in regard to the unsymmetrical dithioacetal.     

1-Bis(methoxy)-4-bis(methylthio)-3-buten-2-one: useful three carbon synthon for synthesis of five and six membered heterocycles with masked (or unmasked) aldehyde functionality

1-Bis(methoxy)-4-bis(methylthio)-3-buten-2-one has been shown to be a useful three carbon synthon for efficient regiospecific synthesis of a variety of five (pyrazole and isoxazole) and six membered (pyrimidines, pyridone and pyridines) heterocycles with masked (or unmasked) aldehyde functionality by cyclocondensation with bifunctional heteronucleophiles such as hydrazine, hydroxylamine, guanidine, thiourea, cyanoacetamide and substituted β-lithioaminoacrylonitriles. Reaction of 1-bis(methoxy)-4-bis(methylthio)-3-buten-2-one with methylene iodide and Zn-Cu couple under Simmons-Smith reaction conditions afforded 2-(methylthio)thiophene-4-aldehyde in good yield, whereas cycloaromatization with thiophene-2- and 3-acetonitriles gave the corresponding substituted benzothiophene-4- and 7-aldehydes in good yields.     

二吡唑基甲酮类化合物的合成和表征

以5-氨基-3-甲硫基-1H-吡唑-4-羧酸乙酯(1)为原料, 依次经肼解、与取代的乙烯酮二硫缩醛缩合和烷基化合成了一系列二吡唑基甲酮类化合物, 经¹H NMR, ¹³C NMR和元素分析确证了它们的结构, 部分化合物进一步经过了质谱表征.     

Synthesis of Asymmetric Propanetriol Analogues

Form natural tartaric acid,(R)-2-benzyloxy-3-(2-tertrahydropyranyloxy) propanol 3 was designed and synthesized, and (R)-2-benzyloxy-3-(4-methoxybenzyloxy)propanol 7 was prepared in a new method. They can be used as chiral synthons of lysophosphatidic acid and other compounds with asymmetric propanetriol backbone.     

Condensation Reaction of α-Aroyl-α-acetyl Ketene Cyclic Dithioacetals with Aromatic Aldehydes

Asaversatilethree-carbonsynthon,a--oxoketenedimethylthioacetalsIhavebeenappliedinmanyfields'.Inourpreviousworks'-',someproperties,especiallyadditionselectivity,ofthearoxoketenecyclicdithioacetals2werefoundtobequitedifferentfromthoseof1.Herea--aroyl...     

A New Jatrophane Diterpenoid Ester from Euphorbia turczaninowii

A new jatrophane diterpenoid ester （2S, 3S, 4R, 5R, 7S, 8R, 13R, 15R） - 3, 5, 7, 8, 15- pentaacetoxy-9, 14-dioxojatropha-6（17）, 11E-diene was isolated from the whole plant of Euphorbia turczaninowii Kar. ＆ Kit.. Its structure was characterized by spectral analysis and confurmed by X-ray crystallographic analysis.     

草酸单乙酯三尖杉碱酯的合成及其在三尖杉酯类生物碱合成中的应用

用醇钠催化的酯交换方法合成了草酸单乙酯三尖杉碱酯(4),并用4和格氏试剂反应,得到合成三尖杉酯类生物碱的关键中间体α-酮酰基三尖杉碱(2),简化了已报道的一些三尖杉酯类生物碱的合成方法。     

Applications of Calixarenes in Polymer Synthesis

Summary: The applications of calixarenes in polymer synthesis have been reviewed. Calixarenes have been used as ligands to prepare rare earth calixarene complexes. A series of rare earth calixarene complexes have been synthesized and employed as efficient catalysts for the polymerization of ethylene, styrene, butadiene, propylene oxide, styrene oxide, trimethylene carbonate, and 5,5-dimethyl trimethylene carbonate. On the other hand, the synthesis and characterization of star-shaped polymers with calixarene as core molecules are also described.     

Synthesis and Applications of Carbohydrate-Based Organocatalysts

Organocatalysis is a very useful tool for the asymmetric synthesis of biologically or pharmacologically active compounds because it avoids the use of noxious metals, which are difficult to eliminate from the target products. Moreover, in many cases, the organocatalysed reactions can be performed in benign solvents and do not require anhydrous conditions. It is well-known that most of the above-mentioned reactions are promoted by a simple aminoacid, l-proline, or, to a lesser extent, by the more complex cinchona alkaloids. However, during the past three decades, other enantiopure natural compounds, the carbohydrates, have been employed as organocatalysts. In the present exhaustive review, the detailed preparation of all the sugar-based organocatalysts as well as their catalytic properties are described.     

Synthesis and properties of novel dialkylaminocarbenium salts

Novel dialkylaminocarbenium salts with metallocomplex counter ions were prepared by the reaction of phosgene with either DMF or tetramethylurea in the presence of metal chlorides. Reactions of organosilicon amides with phosgene gave corresponding carbenium salts, while organosilicon ureas yielded aminoiminocarbenium salts. Dialkylaminochlorocarbenium salts were reduced with hydrosilanes to give dialkylaminocarbenium, salts and can be easily hydrolyzed to afford either amides or ureas. Pathways of the reaction with water and alcohols depend on the nature of reagent and the reaction conditions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1035–1040, May 1997.     

Ketene dithioacetal mediated synthesis of 1,3,4,5-tetrasubstituted pyrazole derivatives and their biological evaluation

Abstract

Ketene dithioacetal mediated chemo- and regioselective synthesis of a series of novel 1,3,4,5-tetrasubstituted pyrazole derivatives (4a-l) integrated with a bioactive indole nucleus was achieved by reacting substituted 2-(1-methyl-1H-indole-3-carbonyl)-3,3-bis-(methylthio)-acrylonitrile (2) and substituted phenyl hydrazine hydrochloride (3) in the presence of a catalytic amount of anhydrous K₂CO₃ under reflux conditions. The structures were ascertained by ¹H NMR, NOESY, ¹³C NMR, FT-IR, and HRMS data. In vitro cytotoxicity evaluation of the synthesized compounds against MCF 7 (breast carcinoma) and normal Vero (monkey kidney) cell lines revealed that the compound 5-(5-Bromo-1-methyl-1H-indol-3-yl)-1-(4-cyano-phenyl)-3-methylsulfanyl-1H-pyrazole-4-carbonitrile (4k) showed significant cytotoxicity against MCF 7 (GI₅₀ = 15.6 µM) with low cytotoxicity against normal Vero cell line. Most of the synthesized compounds were also found to possess excellent anti-inflammatory and antioxidant (DPPH, NO, H₂O₂ and SOR) potential.     

肟的无气味硫缩醛/酮化反应

探讨了以无气味且稳定的α-羰基二硫缩烯酮(1)作为代硫醇试剂的肟(2)的硫缩醛/酮化反应. 在乙酰氯-乙醇(体积分数95%)或4-十二烷基苯磺酸(DBSA)-水体系中及回流条件下, 化合物1与肟2能有效地进行硫缩醛/酮化反应. 反应过程中未闻到硫醇的恶臭气味.     

Cyclocondensation of 2-Fluoro-5-nitrobenzaldehyde with Amidines. New Synthesis of Isoquinolines

The direction of the cyclocondensation of 2-fluoro-5-nitrobenzaldehyde with five amidines having -hydrogen atoms has been studied. It was established that depending on the structure of the amidine the main products of the reaction may be not only quinazolines but also 3-aminoisoquinolines. A new convenient route has been found for the synthesis of 3-aminoisoquinolines consisting of the cyclocondensation of -acylacetamidines with 2-fluoro-5-nitrobenzaldehyde.     

Synthesis of 4-azo-butenolides

An efficient, catalyst-free, microwave-assisted approach has been developed for the synthesis of 4-azo-butyenolides derivatives by condensing tetronic acid with various anilines. This approach exhibited good functional group compatibility and produced the desired products in good to excellent yields in just 30–40?min. This approach can be seen as a better alternative to protocols with long reaction times used for the synthesis of these compounds, which are synthons for the obtaining of quinolines.     

α-乙酰基二硫缩烯酮的新合成方法

本文采用酸为催化剂，实施了具有代表性的各种烷硫基α,α-二乙酰基二硫缩烯酮的脱乙酰基反应，得到了一条简洁、通用的α-乙酰基二硫缩烯酮的合成路线.用浓硫酸作催化剂，以极高的产率(90%—100%)制得到相应的α-乙酰基二硫缩烯酮.同时，通过控制反应时间，还可以得到硫代乙酰乙酸酯类化合物.     

氟替卡松丙酸酯的合成

以双氟美松为原料,经氧化、酯化、酰化、醇解和氟甲基化反应制得氟替卡松丙酸酯(1),总收率60.1%。1和中间体的结构经1H NMR,IR和MS表征。     

Cyanoacetanilides Intermediates in Heterocyclic Synthesis. Part 2: Preparation of Some Hitherto Unknown Ketene Dithioacetal,Benzoazole and Pyridone Derivatives

Ketene dithioacetal 3 , aminopyrazole 5 , tetrazine 7 , benzoazole 9 and pyridone 11 , 12 , 13 and 16 derivatives were prepared from cyanoacetanilide 1 as a starting material.