炔烃分子内环化反应合成含氮杂环化合物研究进展

分子内氮原子参与的炔烃环化反应是构成含氮杂环化合物(例如吲哚类化合物等)的最重要途径之一. 从两个方面对分子内氮杂原子与炔的环化反应研究新进展进行了综述: 过渡金属催化分子内环化反应和分子内亲电环化反应. 此外, 对环化反应的机理也做了较详细的描述.     

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.     

分子内环化对聚乙烯醇交联体系的影响

以聚乙烯醇(PVA)-戊二醛(GA)体系作为研究对象, 系统地研究了分子内环化对凝胶体系的影响, 为水凝胶体系的网络结构评价奠定了一定的实验基础.     

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.     

Intramolecular Ketone-Olefin Radical Cyclization with Low-Valent Titanium Reagent: Synthesis of Benzopyrans

A novel protocol for intramolecular ketyl-olefin radical cyclization with low-valent titanium reagent is outlined. It allows the formation of the benzopyran nucleus from ortho-allyloxy propiophenones as the sole product in moderate yields via intramolecular radical cyclization.     

Synthesis of 4-(Hydroxymethyl)dihydroisoindolium Salts and Their Intramolecular Recyclization

The review discusses intramolecular cyclization of ammonium salts containing a 4-hydroxybut-2- yn-1-yl group in combination with various π⁴-fragments, as well as mechanisms of cyclization and intramolecular recyclization of the resulting 4-(hydroxymethyl)dihydroisoindolium salts and their fused analogs. The process is accompanied by neither ring expansion nor contraction, and a pharmacophoric 1,3-dihydrofuran ring is formed instead of dihydroisoindolium fragment. The effects of electronic and structural factors on the intramolecular cyclization and recyclization processes are considered.     

Sulfur ylides 13. Synthesis and intramolecular cyclization of keto-stabilized sulfur ylides

Keto-stabilized sulfur mono-and bisylides were obtained from N-phthalylglutamic acid and their intramolecular cyclization was studied. The intramolecular cyclization of the ylide obtained at the α-carboxy group gave a product of the pyrrolizidinedione structure; bisylide yielded a cycloheptene derivative as the result of intramolecular recombination of intermediate dicarbene. The ylide obtained at the γ-carboxy group underwent no cyclization, giving methylthio ketone and oxo benzoate. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2771–2776, December, 2005.     

Synthesis of highly functionalized oxazines by Vilsmeier cyclization of amidoalkyl naphthols

The intramolecular cyclization of amidoalkyl naphthols by Vilsmeier reagent produced 1,3-oxazines. The Vilsmeier reagent (chloromethylenedimethylammonium chloride) has been used as an efficient and cheap acid activator for the one-step synthesis of oxazine derivatives. A mechanism involving sequential haloformylation and intramolecular nucleophilic cyclization is proposed.     

Intramolecular metal—double bond interactions : VII. Intramolecular cyclization of alkenyl derivatives of lithium,aluminum, gallium and indium

The intramolecular cyclization reactions of tri-1-hex-5-enyl Group III derivatives and of 1-hex-5-enyllithium have been investigated and it is proposed that the reactions may be depicted as internal addition across the terminal double bonds of the alkenyl species. The cyclization reaction proceeds more readily for the 1-hex-5-enyl derivatives than for any other chain length and is dependent on temperature, concentration and solvent. ¹H NMR data and cryoscopic molecular weight data are presented for several diisobutyialkenyl- and diisobutylalkyl-aluminum derivatives. These data have been interpreted in terms of a direct intramolecular interaction between the metal center and the π-electron system of the olefinic site. The intramolecular cyclization reactions for the 1-hept-6-enyl, 1-oct-7-enyl- and 1-undec-10-enylaluminum derivatives also were investigated and it was found that cyclization occurred only for the 1-hept-6-enyl derivative.     

Unprecedented SnCl2-mediated cyclization of nitro arenes via N-N bond formation

[reaction: see text] A mild, efficient, one-pot protocol for the cyclization of nitro-aryl substrates using SnCl(2) has been described. The mechanistic course of the reaction suggests the involvement of a hydroxylamine intermediate leading to an intramolecular cyclization via N-N bond formation. The versatility of the methodology has been demonstrated by using two nitro-aryl substrates derived from dihydroisoquinolines and dihydro-beta-carbolines. The intramolecular cyclization led to the formation of indazoles in high yields and purities.     

Facile and efficient synthesis of quinolin-2(1H)-ones via cyclization of penta-2,4-dienamides mediated by H2SO4

A facile and efficient synthesis of substituted quinolin-2(1H)-ones is developed via intramolecular cyclization of penta-2,4-dienamides mediated by concentrated H(2)SO(4) (98%), and a mechanism involving the formation of a dicationic superelectrophile, and subsequent intramolecular nucleophilic cyclization reactions is proposed.     

Base catalyzed intramolecular cycloaddition of dialkyl(4-hydroxybutyn-2-yl)[3-(<Emphasis Type="Italic">p</Emphasis>-tolyl)propyn-2-yl]ammonium chlorides and intramolecular recyclization of the products obtained

Dialkyl(4-hydroxybutyn-2-yl)[3-(p-tolyl)propyn-2-yl]ammonium chlorides undergo a diene synthesis type intramolecular cyclization in aqueous base medium to give 2,2-dialkyl-4-hydroxymethyl-6-methyl-benzo[f]isoindolinium chlorides. Under conditions of aqueous base fission intramolecular cyclization of the latter gives 4-dialkylaminomethyl-8-methyl-1,3-dihydronaphtho[1,2-c]furans.     

研究硅酸聚合反应的新途经

用高分子反应统计理论研究了硅酸聚合反应.利用三甲基硅烷化-气相色谱法跟踪测定了聚合反应过程中各低聚态硅酸的含量变化,得到了分子数量分数分布.该分布符合含有内环化因子校正的A₁型缩聚反应统计理论,内环化反应是硅酸聚合反应的重要特征.     

Studies on the oxidative cyclization of 3-hydroxyalkyl-1,2,4-trialkoxynaphthalenes and synthetic application for the biologically active natural compound rhinacanthone

The oxidative intramolecular cyclization of 3-hydroxyalkyl-1,2,4-trimethoxynaphthalenes was investigated. A series of 1,2-naphthoquinone fused cyclic ethers were synthesized directly from 3-hydroxyalkyl-1,2,4-trimethoxynaphthalenes by exposure to diammonium cerium (IV) nitrate. To understand the reaction mechanism, the intramolecular cyclization of 3-hydroxyalkyl-naphthoquinones that were formed as reaction intermediates was also examined. The results suggested that the reaction proceeds by a stepwise oxidation–cyclization mechanism. Using this methodology, five-step synthesis of rhinacanthone was achieved with high yield.     

New Chiral Aminoamidoximes: Syntheses and Investigation of Heterocyclic Compounds

New chiral aminoamidoximes were prepared from (L)-proline, (L)-alanine, and (L)-isoleucine by treatment of the corresponding aminonitriles with hydroxylamine in the presence of triethylamine. The intramolecular cyclization with α-bromoacid chlorides and aldehydes was investigated to give new 1,2,4-oxadiazin-6-ones and 1,2,4-oxadiazoles, respectively. These compounds were likely to undergo an intermolecular cyclization through oxygen and nitrogen. However, intramolecular cyclization through two nitrogens did not occur even after changing reaction conditions.     

Synthesis of indolequinones via a Sonogashira coupling/cyclization cascade reaction

A mild strategy for constructing indolequinone motifs is described on the basis of the Sonogashira reaction and a copper-catalyzed intramolecular cyclization cascade reaction. The first step involves the palladium- and copper-catalyzed reaction between halogenated naphthoquinone and terminal acetylene to generate a coupling product, which then reacts in a copper-catalyzed intramolecular cyclization with the nitrogen functional group adjacent to the carbon-carbon triple bond.     

Can Flory-Stockmayer theory be applied to predict conventional free radical polymerization of multivinyl monomers? A study via Monte Carlo simulations

The conventional free radical polymerization (FRP) of multivinyl monomers (MVMs) inevitably leads to gelation even at low monomer conversion resulting in difficulties to control and monitor the reaction process. Flory and Stockmayer (F-S theory) studied it based on two fundamental assumptions: (1) independent and equivalent vinyl groups; (2) no intramolecular cyclization. However, until now its applicability to FRP of MVMs (especially regarding the extent of intramolecular cyclization) is still controversial. In this paper, Monte Carlo simulations are used to study FRP of divinyl monomers by two kinetic models: with/without cyclization models. The results of the simulations are compared with the calculated gel points based on F-S theory and the experimental data. It is found that the intramolecular cyclization has a negligible impact on the polymerization process and the gel point before gelation, which are in agreement with the prediction by F-S theory, but the effect becomes significant above the gel points.     

Growing Impact of Intramolecular Click Chemistry in Organic Synthesis

Click Chemistry, a modular, rapid, and one of the most reliable tool for the regioselective 1,2,3-triazole forming [3+2] reaction of organic azide and terimal alkyne is widely explored in various emerging domains of research ranging from chemical biology to catalysis and medicinal chemistry to material science. This regioselective reaction from a diverse range of azido-alkyne scaffolds has been well performed in both intermolecular as well as intramolecular fashions. In comparison to the intermolecular metal (Cu/Ru/Ni) variant of ‘Click Chemistry’, the intramolecular click tool is little addressed. The intramolecular click chemistry is exemplified as a mordern tool of cyclization which involves metal-catalyzed (CuAAC/RuAAC) cyclization, organo-catalyzed cyclization, and thermal-induced topochemical reaction. Thus, we report herein the recent approaches on intramolecular azide-alkyne cycloaddition ‘Click Chemistry‘ with their wide-spread emerging applications in the developement of a diverse range of molecules including fused-heterocycles, well-defined peptidomemics, and macrocyclic architectures of various notable features.     

Photochemical reactions of N-alkyl and N,N-dialkylimidazolidinetriones

N-Akyl and N,N-Dialkylimidazolidinetriones undergo intramolecular hydrogen abstraction on irradiation to give elimination, intramolecular disproportionation, and cyclization products.     

Heterocyclization of Cyanoacetamide Derivatives: Synthesis and Biological Activity of Novel Azoles and Azines

Russian Journal of Organic Chemistry - The intermolecular cyclization of N-benzyl-2-cyanoacetamide with carbon disulfide followed by intramolecular cyclization gave thioxothiazinone 3. This...