一锅法合成2-硫脲嘧啶

采用一锅法合成了2-硫脲嘧啶,最佳反应条件为:硫脲33 mmol,n(乙酸乙酯)∶n(甲酸乙酯)∶n(甲醇钠)∶n(硫脲)=2.5∶2.0∶1.5∶1.0;乙酸乙酯与甲醇钠在甲苯(35 mL)中于80℃反应3 h;冷却后滴加甲酸乙酯,于25℃充分搅拌8 h后加入硫脲的乙醇(10 mL)溶液,回流反应3 h,收率54.7%。     

New Synthesis of Uracil and 2-Thiouracil

Uracil (4) and 2-thiouracil (5) were easily obtained from Meldrum's acid and urea or thiourea in two steps.     

新型GPR40激动剂的合成及其生物活性

以丁炔二醇为起始原料,用叔丁基二甲基氯硅烷进行单保护后,与2-(6-羟基-2,3-二氢苯并呋喃)乙酸甲酯经Mitsunobu反应制得2-{6-［4-(叔丁基二甲硅烷氧基)丁-2炔基氧基］-2,3-二氢苯并呋喃}乙酸甲酯(3); 3脱除保护后与苯酚衍生物发生Mitsunobu反应,随后经水解合成了6个结构新颖的苯并二氢呋喃衍生物(7a~7f),其结构经¹H NMR, ¹³C NMR和HR-EI-MS表征。GPR40激动活性测试结果表明：7a~7f对GPR40均有激动作用,其中7e和7f激动活性最强,EC₅₀分别为0.593 μmol·L^-1和0.596 μmol·L^-1。     

Synthesis of 2-Pyrrolidinones by The Cyclization of N-Allylhaloacetamides

2-Pyrrolidinones have been synthesized by the cyclization of N-allylhaloacetamides in the presence of ferrous salts.     

关环反应合成鸢尾酮

研究了以9,10-环亚甲基假紫罗兰酮为原料,经关环反应合成鸢尾酮的工艺,并对该关环反应机理进行了初步探讨。实验结果表明,适宜的工艺条件为:反应温度-70℃,物料摩尔比n(9,10-环亚甲基假紫罗兰酮)∶n(氯磺酸)为1∶4,反应45 min,鸢尾酮的收率为90.1%。产品中α-鸢尾酮、β-鸢尾酮和γ-鸢尾酮的含量分别为60.2%、29.0%和8.0%(GC,峰面积归一化法);采用NMR确证了α-鸢尾酮的结构。关环反应机理的初步探讨表明关环反应应在低温下快速完成。     

分子内Friedel-Crafts环化反应在苯并环状物合成中的应用

Friedel-Crafts反应是有机合成中最有用的反应之一,它的应用范围十分广泛.Friedel-Crafts反应也是合成环状化合物的重要途径,尤其分子内的环化反应一直以来受到广泛的关注.对近年来应用分子内Friedel-Crafts环化反应合成苯并环状化合物进行了详细的综述,并对分子内Friedel-Crafts环化反应在有机合成上发展前景作了展望.     

Lactone Radical Cyclizations and Cyclization Cascades Mediated by SmI(2)-H(2)O

Unsaturated lactones undergo reductive radical cyclizations upon treatment with SmI(2)-H(2)O to give decorated cycloheptanes in a single highly selective operation during which up to three contiguous stereocenters are generated. Furthermore, cascade processes involving lactones bearing two alkenes, an alkene and an alkyne, or an allene and an alkene allow "one-pot" access to biologically significant molecular scaffolds with the construction of up to four contiguous stereocenters. The cyclizations proceed by the trapping of radical anions formed by electron transfer reduction of the lactone carbonyl.     

Synthesis of Di‐peri‐dinaphthoporphyrins by PtCl2‐Mediated Cyclization of Quinodimethane‐type Porphyrins

Di‐peri‐dinaphthoporphyrins can be regarded as a key and common substructure of fused porphyrinoids. PtCl₂‐mediated cycloisomerization reaction of quinodimethane‐type porphyrins provided these doubly fused porphyrins, which exhibit characteristic paratropic ring currents that presumably arise from 24π antiaromatic circuit as a dominant resonance contributor. UV/Vis absorption spectra, cyclic voltammetry, and excited‐state dynamics as well as theoretical calculation support this conclusion.     

Synthesis of Isoindolinones by Palladium-Catalyzed Carbonylative Cyclization of 2-Bromobenzaldehyde with Diamines

2-Bromobenzaldehyde reacts with diamines under carbon monoxide in the presence of a catalytic amount of a palladium complex to afford the corresponding tricyclic isoindolinones in fair to good yields.     

Synthesis of 3-Methylthio-benzo[b]furans/Thiophenes via Intramolecular Cyclization of 2-Alkynylanisoles/Sulfides Mediated by DMSO/DMSO-d6 and SOCl2

The reaction of 2-alkynylanisoles/sulfides with SOCl2 and DMSO was conducted to conveniently furnish the biologically interesting 3-(methylthio)-benzo[b]furans/...     

Electronic Absorption Spectra of Some 2-Thiouracil Derivatives

Abstract

The electronic absorption spectra of 2-thiouracil and some of its derivatives were investigated using polar and nonpolar solvents. The present analysis is facilitated via computer deconvolution of the observed spectra and molecular orbital (MO) computations. Comparison between the experimentally observed and theoretically computed spectra in addition to a quantitative assignment of all transitions observed were undertaken. The computed dipole moments are used to indicate the polarity of the excited state and hence predict its solvent dependence. The spectra are, in general, very well predicted and assigned using INDO/S computational results. The spectrum of the trifluoro derivative is much more complicated and the corresponding states show much more solvent dependence than those observed for other thiouracil studied.     

碲、硒叶立德在立体选择性小环化反应中的应用

概述了碲及硒叶立德在立体选择性小环化反应中的应用, 包括环丙烷化反应、环氧化反应、氮杂环丙烷化反应等.     

Novel Reductive Dimerization Cyclization of 1,1-Dicyanoalkenes Mediated by Zinc in Aqueous Media

Zinc-mediated reductive dimerization cyclization of 1,1-dicyanoalkenes 1 occurs to give functionalized cyclopentenes 2(cis) and 3(trans) in good yields under saturated aqueous NH₄Cl-THF solution at room temperature. 3 is major product.     

Efficient Synthesis of 3-Aryl-5-chloroindan-1-ones via Free Radical–Mediated Intramolecular Cyclization

An efficient free radical–mediated intramolecular cyclization strategy has been developed for the synthesis of 3-aryl-5-chloroindan-1-ones. Variously substituted 2,4-dichloroenones afforded 3-aryl-5-chloroindan-1-ones in quantitative yields upon intramolecular cyclization under free radical conditions.     

A Facile Synthesis of 2-Oxazolines via Dehydrative Cyclization Promoted by Triflic Acid

2-oxazolines are common moieties in numerous natural products, pharmaceuticals, and functional copolymers. Current methods for synthesizing 2-oxazolines mainly rely on stoichiometric dehydration agents or catalytic dehydration promoted by specific catalysts. These conditions either generate stoichiometric amounts of waste or require forcing azeotropic reflux conditions. As such, a practical and robust method that promotes dehydrative cyclization while generating no byproducts would be attractive to oxazoline production. Herein, we report a triflic acid (TfOH)-promoted dehydrative cyclization of N-(2-hydroxyethyl)amides for synthesizing 2-oxazolines. This reaction tolerates various functional groups and generates water as the only byproduct. This method affords oxazoline with inversion of α-hydroxyl stereochemistry, suggesting that alcohol is activated as a leaving group under these conditions. Furthermore, the one-pot synthesis protocol of 2-oxazolines directly from carboxylic acids and amino alcohols is also provided.