Highly active binuclear Cu(Ⅱ) catalyst bearing an unsymmetrical bipyridine-pyrazole-amine ligand for the azide-alkyne cycloaddition reaction

Ligands containing NH groups often show special characteristics.In this paper,a well-defined dinuclear Cu（II） complex bearing an unsymmetrical bipyridine-pyrazole-amine ligand was synthesized by the condensation of N–H to release H2O.Using sodium L-ascorbate as a reductant,the binuclear complex showed excellent activity in 1,3-dipolar cycloaddition reactions between alkynes and azides to obtain 1,4-disubstituted triazoles in 95%–99% isolated yields.

A one-pot protocol for copper-mediated azide–alkyne cycloaddition using alkenyl triflate precursors

On the basis of the mild transformation of alkenyl triflates into alkynes promoted by LiCl, a one-pot protocol using alkenyl triflate precursors was developed for copper-mediated azide–alkyne cycloaddition. This protocol may provide an opportunity of sequentially click reactions for the construction of bifunctional probes in chemical biology studies.

Rhodium Catalyzed [2π + 2π + 2π]-Cycloaddition of Alkynyl-Ynamides and Carbon Disulfide to Indolo-Thiopyrane Thiones

The synthesis of new indoloannulated thiopyranethiones is reported. The key-step is a rhodium-catalyzed [2 + 2 + 2]-cycloaddition of alkynyl-ynamides with carbon disulfide to close the pyrrole and the thiopyranethione rings simultaneously. A violet idolothiopyrane thione or a mixture of the violet and a red isomer result from [RhCl(C8H14)2]2/3BINAP catalyzed cycloadditions, the regiochemistry is controlled by the substitution pattern on the alkynyl-ynamide.

SYNTHESIS AND CHARACTERIZATION OF TRIAZOLE CONTAINING LIQUID CRYSTALLINE POLYMERS THROUGH 1,3-DIPOLAR CYCLOADDITION POLYMERIZATION

Liquid crystalline polymers containing 1,2,3-triazole units as linking groups have been synthesized from the monomers containing triad ester diazide and flexible dialkyne ester by 1,3-cycloaddition reaction and were characterized. Click reaction of azide and alkyne functionals catalyzed by Cu(I) yielded target polyesters with 1,2,3-triazole groups.The structure of the polymer was confirmed by spectral techniques.GPC analysis reveals that the polymers have moderate molecular weight with narrow distribution.H...

Theoretical Study of 1,3-Dipolar Cycloaddition of Hydrazoic Acid to Substituted Ynamines

The 1,3-dipolar cycloaddition reactions of various substituted ynamines with hydrazoic acid were theoretically investigated with the high-accuracy CBS-QB3 method. Two regioisomers, 4-amine, and 5-amine substituted adducts, were obtained, with the former as the preferred yield. This regioselectivity is rationalized by the frontier molecular orbital theory. The reactivity and synchronicity are enhanced with the increase of the electron-withdrawing character of the substitute on ynamine fragment. The calculations also show that the effect of solvent increases the activation energy, and the reaction becomes even harder in polar solvent.

Microwave-assisted Synthesis of New 1,2,3-Triazoles Bearing an Isoxazole Ring by the Azide-alkyne Cycloaddition Click Chemistry

A comparison synthesis of 1,2,3-triazoles bearing isoxazole ether was developed between conventional and microwave-assisted heating. Single/donble 1,2,3-triazoles bearing isoxazole ether were synthesized by click reaction starting from substituted isoxazolyl alkyne compounds and substituted benzyl azide compounds or neopen- tylglycol diazide in the presence of copper（I） that in-aim generated. Herein, the effect of different catalysts on the yield was researched by conventional method, and the optimal catalyst was selected. The structures of all the synthe- sized compounds were confirmed by MS, FTIR, ^1H and ^13C NMR spectroscopies. Moreover, the crystal structure of 5-{[（1-benzyl-1H-1,2,3-triazol-4-yl）methoxvlmethvl}-3-（4-fluoroohenvl）isoxazole（2h） was determined.

AZIDE-ALKYNE CLICK POLYMERIZATION:AN UPDATE

The great achievements of click chemistry have encouraged polymer scientists to use this reaction in their field. This review assembles an update of the advances of using azide-alkyne click polymerization to prepare functional polytriazoles（PTAs） with linear and hyperbranched structures.The Cu（I）-mediated click polymerization furnishes 1,4-regioregular PTAs,whereas,the metal-free click polymerization of propiolates and azides produces PTAs with 1,4-regioisomer contents up to 90%.The PTAs display advanced functions,such as aggregation-induced emission,thermal stability,biocompatibility and optical nonlinearity.

Carboxymethyl glycoside lactone(CMGL) synthons:Scope of the method and preliminary results on step growth polymerization of α-azide-ω-alkyne glycomonomers

Carboxymethyl glycoside lactones(CMGLs) are bicyclic synthons which open readily for accessing new types of pseudo-glycoconjugates,such as sugar-amino acid hybrids,neoglycolipids,pseudodisaccharides,and membrane imaging systems.After lactone opening,free OH-2 is available for further functionalization,leading to 1,2-bisfunctionalized derivatives.This strategy is illustrated herein with new polymerizable systems of the AB type bearing both azide and alkyne functions prepared from α or β gluco-CMGL synthons.After the reaction of lactones with propargylamine,an azido group was introduced by two different sequences leading to either the 2-manno-azido or the 6-gluco-azido products.The capability of these AB monomers to undergo step growth polymerization through copper(I) catalyzed alkyne-azide cycloaddition(CuAAC) and generate glycopolytriazoles was evidenced.

Formal[2+1]Cycloadditions of a Metallacyclopentadiene Unit with Alkynes:Constructing Tetracyclic Conjugated Frameworks with Bridgehead Metals

Comprehensive Summary Metallacyclopentadienes play a vital role in transition-metal mediated and catalyzed cycloaddition reactions of alkynes.Though versatile reactions of metallacyclopentadienes with alkynes have been disclosed,[2+1]cycloadditions of metallacyclopentadienes and alkynes have never been discovered.In present work,we report the formal[2+1]cycloadditions of a metallacyclopentadiene unit with a broad scope of commercial alkynes,providing a facile strategy to construct tetracyclic conjugated compounds.The deuterated experiment indicates a metal vinylidene intermediate has been involved in[2+1]cycloaddition.Moreover,the electrophilic substitution reaction of the tetracyclic conjugated compound with the aid of density functional theory(DFT)calculated Fukui functions is investigated.

Syntheses of N-sulfonyl-N,N-disubstituted amidines via a three-component free-radical coupling reaction of tertiary amines and arenesulfonyl azides with terminal alkynes

A facile and efficient synthesis of N-sulfonyl-N,N-disubstituted amidines has been achieved via a CuI-catalyzed three-component free-radical coupling reaction of tertiary amines and arenesulfonyl azides with terminal alkynes in the presence of azodiisobutyronitrile(AIBN).The reaction mechanism of this reaction has also been studied.

Synthesis of polynorbornene with pendant moiety bearing azide and terminal alkyne groups

A powerful approach to the synthesis of an unprecedented polynorbornene with pendant moiety bearing azide and terminal alkyne groups is developed. Two key intermediates, namely, 3-azido-5-（2-（trimethylsilyl）ethynyl） benzyl alcohol and 4-（4-azatricyclo [5.2.1.0^2.6]dec-8-en-4-yl） benzoic acid, were optimally synthesized for convergent synthesis of the corresponding monomer.

Facile Synthesis of 4,5-Disubstituted 2H-1,2,3-Triazoles by Catalyst-free Cycloaddition between Substituted Vinyl Sul- fones and Sodium Azide under Ambient Conditionst

A highly efficient method for readily preparing 4,5-disubstituted 2H-1,2,3-triazoles was found. Under ambient conditions, a catalyst free cycloaddition between substituted vinyl sulfones and sodium azide could be completed in a very short time. In this cycloaddition process, sulfonyl group acts as a leaving group, while its ester group was retained.

Synthesis of 5-functionalized-1,2,3-triazoles via a one-pot aerobic oxidative coupling reaction of alkynes and azides

In this paper, an efficient synthesis of 5-alkynyl-1,2,3-triazoles through a one-pot aerobic oxidative coupling reaction of various alkynes and azides has been developed. Further derivatization of 5-alkynyl-1,2,3-triazoles readily yielded 5-carbonyl-1,2,3-triazoles, 5-carboxylic-1,2,3-triazole, 5-hydroxyalkyl-1,2,3-triazoles and 5-quinoxaline-1,2,3-triazole, which provided an entry into structurally diverse 5-functionalized-1,2,3-triazoles.

A dicationic,podand-like,ionic liquid water system accelerated copper-catalyzed azide-alkyne click reaction

In this work,an effective,task specific,dicationic,podand-like ionic liquid was synthesized and applied to improve the capability features of click reaction.Moreover,to broaden the scope and decreasing the serious limitations of preparation methods of organic azides,a simple green procedure for the preparation of alkyl azides,the fundamental starting materials in click reactions,from alcohols under solvent-free conditions and microwave irradiation has been reported,for the first time.

Organocatalytic asymmetric[2+2] cycloaddition of alkynes with quinones

A chiral phosphoric acid catalyzed enantioselective[2+2] cycloaddition of alkynylindols or alkynylnaphthols with quinones is disclosed.A class of functionalized cyclobutenes with excellent yields,diastereo-and enantioselectivities were prepared under mild reaction conditions(70 examples,up to 99%yield,99%ee,all>50:1 dr).Mechanistic studies revealed that a dearomatization of indole or naphthol occurred to initiate the cycloaddition,followed by an intramolecular Michael addition with in situ generated allene-iminium or vinylidene-quinone methide intermediate.The competitive[2+3] cycloaddition was prevented in this catalytic system.An interesting central to axial chirality conversion via a rearrangement process was realized during transformation of the product.

Synthesis, Characterization and Crystal Structures of Zwitterionic Triazolato Complexes by Reaction of a Ruthenium Azido Complex with Excess Ethyl Propiolate

The synthesis and structures of two novel zwitterionic ruthenium triazolato complexes are reported. The treatment of the ruthenium azido complex [Ru]-N3 (1, [Ru] = (η5-C5H5)(dppe)Ru, dppe = Ph2PCH2CH2PPh2) with an excess of ethyl propiolate in CHCl3 or CH2Cl2 under ambient conditions for 15 days results in the formation of a mixture of the Z- and E-forms of N(1)-bound ruthenium 3-ethylacryl-4-carboxylate-3H-1,2,3-triazolato complexes [Ru]N3(CH=CHCO2Et)C2H(CO2) (Z-3) and (E-3) in a ratio of ca. 5:2. The structures of E-3 and Z-3 were confirmed by single-crystal X-ray diffraction analysis and fully characterized by 1H, 31P, 13C NMR and IR spectroscopy, mass spectrometry, and elemental analysis. The negatively charged carboxylate moieties of the zwitterionic ruthenium triazolato complexes Z-3 and Z-3 are highly nucleophilic and reactive toward a variety of electrophiles, making Z-3 and Z-3 potential starting materials for the development of biologically active 1,2,3-triazole derivatives.

纳米纤维素的点击反应改性及应用研究进展

纳米纤维素是从植物细胞壁中提取的一种直径小于100 nm的棒状、须状或纤丝状纤维素,具有密度低、可再生、可降解和生物相容性等特性,同时具有模量高、热膨胀系数低等优点。纳米纤维素表面化学性质单一,含有大量羟基,具有强亲水性质,限制了其应用范围。纤维素表面大量活泼的羟基为进行化学改性提供了各种可能性。通过对纳米纤维素进行表面化学修饰或功能化以拓展其应用领域。点击化学具有高度选择性、模块化、产率高、反应迅速等优点,反应条件相对简单,对水、氧气都不敏感。近年来,点击化学越来越多地被用于纳米纤维素的化学改性和功能化。本文主要综述了点击化学中叠氮-炔基和硫醇-烯烃两类反应用于纳米纤维素改性的研究进展,简单概述了点击反应改性的纳米纤维素在复合材料、水凝胶和气凝胶等方面的应用,最后总结了基于点击化学策略制备、改性和应用纳米纤维素所面临的困难和挑战。

可见光介导下有机光敏剂诱导三氮唑化合物的合成

光诱导反应与有机金属催化、小分子催化和不对称催化等反应实现了许多结构复杂的杂环化合物和天然有机化合物的合成,丰富和发展了有机反应方法学的研究内容。在众多的杂环化合物中,三氮唑是一类重要的具有生物和药理活性的五元杂环化合物,被广泛应用于医药、农药以及其他精细化工领域。基于此,该研究以取代的叠氮和苯甲酰乙腈作为原料、芘作为有机光催化剂,在可见光介导下,通过[3+2]环加成合成一系列1,4,5-取代的1,2,3-三氮唑化合物,并以核磁氢谱、碳谱、高分辨质谱和熔点等数据对相应目标化合物进行了表征。实验结果表明:该反应条件温和、区域选择性高、官能团兼容性好,反应操作简单,产率高达99%。反应机理揭示了该光照转化的可能反应历程。该研究为1,2,3-三氮唑衍生物的合成提供了一种简单、高效、绿色的方法,同时,丰富了三氮唑杂环化合物的分子库。

Facile synthesis of phthalan derivatives via a Pd-catalyzed tandem hydroalkynylation,isomerization,Diels-Alder cycloaddition and aromatization reaction

A novel Pd-catalyzed tandem reaction involving hydroallojnylation, isomerization, Diels-Alder cycloaddition and aromatization reaction to produce phthalan derivatives in moderate yields is reported. The reaction is atom economical and occurs in a highly ordered fashion. The reaction mechanism is discussed.

One-pot synthesis of tetrahydroindoles via a copper catalyzed N-alkynation/[4+2] cycloaddition cascade

A CuSO_4 catalyzed ynamide formation/[4+2] cycloaddition relay reaction was achieved in one-pot.Various 4,7-cis-dihydroindolines were produced in good to high yields. The one-pot operation in conjunction with the cheap and benign copper catalysis renders this reaction highly sustainable.