Synthesis of 2-Fluoroalkylated Tetrahydrofuran Derivatives from Ethyl α-Fluoroalkylacetates

Fluorine-containingheterocycliccompoundsattractincreasingattentionduetotheiruniquepropertiesandbiologicalactivities[l].Recentl}.muchefforthasbeendevotedtothedeve1opmentofneuandefficientmethods1brthesynthesisofsuchcompounds,Amongthem.fluorine-containingbuildingblockstrategiesha\ieprovedtobesuperiortoothermethods[2].S}/nthesisoffuranderi\'ativeshasrecei\/edmuchattentionbecausethefurannucleusrepresentsthemainstructuralelementofseveralnaturalproductsandusefu1ke\-intermediates[3I.Sothesynthesisoff…     

Synthesis and Characterization of α-Bromo Chalcone Derivatives

α-Bromo chalcones containing 2-thiene ring were prepared in good yields by the condensation of 1-(thien-3-yl)ethanone with aromatic aldehydes, followed by bromination with bromine and selective dehydrobromination with triethyl amine at room temperature.     

Synthesis of α-N-Ethylamino Acids and their Derivatives

 A new synthesis of α-N-ethylamino acids starting from α-amino acids using hexafluoroacetone as protecting and activating agent is described. The hexafluoroacetone-protected N-ethylamino acid derivatives obtained are activated lactons. Therefore, they can be directly transformed without the need of an additional activation step with various nucleophiles into the corresponding carboxylic acid derivatives.     

Synthesis of β-Dimethylaminoethyl and α-Hydroxy-β-Dimethylaminoethyl Derivatives from Organolithium Compounds and Tetramethyoxamide

The important biological activity of a variety of aromatic and heterocyclic systems having β-dimethylaminoethyl side chains and their α-hydroxy analogs (c.f. bufotenin, N-methylepinephrine, etc.) has focused the attention of the organic chemist on methods of introducing these functions, and a variety of approaches have been developed. A convenient synthesis has recently been reported³, which utilizes the α-hydroxy-β-dimethylaminoethyl function as an intermediate in the preparation of β-dimethylaminoethyl derivatives, thus providing either or both of these pharmacophoric groups.     

Synthesis of Chiral Cyclohexenones from α-Campholenic,Fencholenic, and β-Campholenic Derivatives

Summary. Optically active dimethylcyclohexenones, potential building blocks for enantioselective syntheses of various naturally active substances, were prepared. These compounds were obtained by oxidation with KMnO₄/Pb(OAc)₄ or ozonolysis of the corresponding cyclopentenic precursors, followed by aldol condensation. During the course of the preparation intermediate diols and chiral polyfunctional carbonyl derivatives were separated and identified analytically.     

Synthesis of New Thiazine and Thiosemicarbazone Derivatives from D-Xylose

Thioureas have strong antifungal activities1 and their antimicrobial and insecticidal properties have been documented for more than fifty years2. Recently thiourea derivatives have been reported to possess antitubercular, antithyroid and anticancer3 prope…     

Synthesis and 125Te NMR Spectroscopy of α-Tellurocarbonyl Compounds and Derivatives

The reaction of lithium alkyl-, alkenyl-, alkynyl-, and aryl tellurolates with α-bromocarobonlyl compounds in anhydrous tetrahydrofuan gives the title compounds in yields ranging from 55–92%. The ¹²⁵Te NMR chemical shift range for these compounds is 405–1024 ppm.     

Design and Synthesis of Novel Aryloxyalkyl-arylpiperazine Derivatives as αlA-Adrenoceptor Antagonists

A series of 1-[2-(substituted phenoxy)ethyl]-4-(2-methoxyphenyl)-piperazine derivatives have been synthesized. The radioligand receptor binding assay indicated that most of them bind with α1-adrenoceptor specifically, and one of the compound possessed subtype A selectivity.     

Synthesis of Isoquinoline Derivatives from β-Hydroxyarylethanamides

A simple and efficient protocol for the construction of medicinally important substituted isoquinolines through intramolecular cyclization of β-hydroxyarylethanamides using acetic anhydride and phosphorous pentoxide in dioxane has been described. The chemo- and regioselectivities due to the influence of different catalysts were investigated and optimized for good to excellent yields. All the synthesized compounds have been characterized by NMR and mass spectral analyses.     

Synthesis and Anti-influenza Virus Activity of Ethyl 6-Bromo-5-hydroxyindole-3-carboxylate Derivatives

A series of ethyl 6-bromo-5-hydroxyindole-3-carboxylate derivatives were synthesized and their in vitro anti-influenza virus activity was evaluated. All the compounds were characterized by ^1H NMR and MS.     

由α-氰基肉桂酸乙酯/N-溴代苯甲酰胺合成2-噁唑啉衍生物

作为重要的杂环化合物,合成新的2-噁唑啉衍生物以及发展其新的合成方法具有重要意义,为此以α-氰基肉桂酸乙酯衍生物为底物,以N-溴苯甲酰胺为反应试剂,在无水碳酸钠(相对于底物3为110%摩尔分数)促进下,在丙酮溶剂中,室温下,建立了合成相应2-噁唑啉衍生物的新方法,共合成了11个新化合物,其结构由核磁共振波谱仪(~1H NMR,~(13)C NMR)和高分辨质谱(HRMS)确认。结果显示,各种α-氰基肉桂酸乙酯衍生物(3a~3k)可被顺利的转化成相应的2-噁唑啉衍生物(5a~5k)。在室温下,丙酮作溶剂,以Na_2CO_3为促进剂时,相应产物的最高收率可达90%。不仅α-氰基肉桂酸乙酯衍生物(3)可被用作该反应的底物,而且α-乙氧甲酰基肉桂酸乙酯(6)也适用于该反应。实验结果还证明,除了N-溴代苯甲酰胺外,N-溴代对硝基苯甲酰胺(8)及N-溴代乙酰胺(9)也适用该反应,证明该方法具有广泛的适应性。根据实验结果,提出了可能的反应机理,该机理支持了形成2-噁唑啉衍生物的区域选择性。     

Aminobromination of Ethyl α-Cyanocinnamate Derivatives with 1,3-Dibromo-5,5-dimethylhydantoin(DBDMH) as Nitrogen and Halogen Sources

1,3-Dibromo-5,5-dimethylhydantoin(DBDMH) was found to be a new and efficient nitrogen/halogen source for the aminobromination of ethyl α-cyanocinnamate derivatives catalyzed by K₃PO₄. The reaction afforded the aminobrominated products in high yields at room temperature, and the full regiospecificity of all the products were achieved. A possible pathway involving a Michael addition for this aminobromination was suggested.     

2-Hydroxymalonitrile-A Useful Reagent for One-step Synthesis of α-Hydroxy Esters

An efficient one-pot synthesis of α-hydroxy esters by employing the useful reagent 2-hydroxymalononitrile reacting with an aldehyde or ketone in just one step has been reported.     

Regioselectivity of Reactions of Nitrogen and Carbon Nucleophiles with Coumarin Derivatives

Abstract

Reaction of various 3‐substituted coumarins with nitrogen and carbon nucleophiles appears to involve, in all cases examined, exclusive, direct substitution at the exocyclic C‐1′ electrophilic center.     

2-(4-溴甲基苯基)丙酸乙酯的合成

以甲苯为原料,对甲苯磺酰乳酸乙酯为Friedel—Crafts烷基化试剂,N-溴代丁二酰亚胺为溴化剂,合成了洛索洛芬的关键中间体——2-（4-溴甲基苯基）丙酸乙酯。其结构经1^H NMR,IR和MS表征。优化反应条件为：催化剂50．0g,回流反应6h,甲苯104．0mL,侧链溴化的引发剂为过氧化苯甲酰。总收率70％。     

氯化锌催化合成3-取代-4(3H)-喹唑啉酮衍生物

室温、无溶剂条件下,氯化锌可有效催化邻氨基苯甲酸、原甲酸酯和胺三组分"一锅法"合成一系列3-取代-4(3H)-喹唑啉酮衍生物。考察了反应条件对产率的影响,确定优化反应条件为n酸:n酯:n胺=1∶1.2∶1.2,ZnCl21(mol)%。该方法条件温和,产率较高,操作简单,且对环境友好。产品结构经IR,1HNMR,元素分析进行表征。     

Preparation of N-Acetyl-2-arylglycin Esters by N-H Insertion Reaction of Aryldiazoacetates with Acetamide

The intermolecular N-H insertion reaction of methyl α-diazo α-arylacetate with acetamide has been investigated using transition-metal complexes as catalysts. The Cu(II) complex Cu(hfacac)₂ (hfacac represents hexafluoroacetylacetonate) has proven to be the most active catalyst to yield methyl N-acetyl-2-phenylglycin in good isolated yield (73–80%) with 3 mmol% of catalyst loading in reflux toluene. The catalyst is also valuable to the substituted aryldiazoacetates at the 4-position on phenyl ring.     

Silica gel catalyzed α-bromination of ketones using N-bromosuccinimide: An easy and rapid method

An easy and rapid method for the a-bromination of ketones using N-bromosuccinimide(NBS) catalyzed by silica gel in methanol under reflux conditions was developed. The expected products were formed in excellent isolated yields within a short period of time(5–20 min). Major advantages of the present procedure include use of inexpensive and readily available catalyst, exclusion of pre- and post-chemical treatment of catalyst and use of methanol as solvent instead of ethers and chlorinated solvents.     

齐墩果酸的结构修饰和α-葡萄糖苷酶抑制活性

以天然五环三萜类化合物齐墩果酸为原料, 通过氧化、酯化、环合和曼尼希等反应, 对A环2, 3位和28位进行结构修饰, 设计合成了16个衍生物; 通过理化性质、质谱和核磁数据确定了化合物结构. 对合成的衍生物进行了体外α-葡萄糖苷酶抑制活性筛选, 结果表明, 受试化合物在200 μg/mL浓度下显示出不同程度的酶抑制活性. 初步构效关系分析表明, 28位游离羧基是活性必需基团, 3位羟基或相应的氢键供体取代基有利于提高活性.     

以乙腈为氰甲基源合成氰基化的偕二氟烯烃

报道了以乙腈为氰甲基源,LiHMDS为碱,在室温下通过氰甲基化α-（三氟甲基）芳基乙烯,合成了一系列氰基化的偕二氟烯烃.该方法具有反应条件相对温和、反应迅速、操作简单、官能团兼容性较好、收率较高等优点.