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1.
Nucleic Acids Res ; 48(13): 7356-7370, 2020 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-32520335

RESUMO

To enable the optimal, biocompatible and non-destructive application of the highly useful copper (Cu+)-mediated alkyne-azide 'click' cycloaddition in water, we have isolated and characterized a 79-nucleotide DNA enzyme or DNAzyme, 'CLICK-17', that harnesses as low as sub-micromolar Cu+; or, surprisingly, Cu2+ (without added reductants such as ascorbate) to catalyze conjugation between a variety of alkyne and azide substrates, including small molecules, proteins and nucleic acids. CLICK-17's Cu+ catalysis is orders of magnitude faster than that of either Cu+ alone or of Cu+ complexed to PERMUT-17, a sequence-permuted DNA isomer of CLICK-17. With the less toxic Cu2+, CLICK-17 attains rates comparable to Cu+, under conditions where both Cu2+ alone and Cu2+ complexed with a classic accelerating ligand, THPTA, are wholly inactive. Cyclic voltammetry shows that CLICK-17, unlike PERMUT-17, powerfully perturbs the Cu(II)/Cu(I) redox potential. CLICK-17 thus provides a unique, DNA-derived ligand environment for catalytic copper within its active site. As a bona fide Cu2+-driven enzyme, with potential for being evolved to accept only designated substrates, CLICK-17 and future variants promise the fast, safe, and substrate-specific catalysis of 'click' bioconjugations, potentially on the surfaces of living cells.


Assuntos
Cobre/metabolismo , Reação de Cicloadição/métodos , DNA Catalítico/química , Alquinos/química , Azidas/química , Química Click/métodos , Oxirredução , Água/química
2.
Science ; 368(6494): 1007-1011, 2020 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-32467391

RESUMO

Bryostatins are a family of 21 complex marine natural products with a wide range of potent biological activities. Among all the 21 bryostatins, bryostatin 3 is structurally the most complex. Whereas nine total syntheses of bryostatins have been achieved to date, bryostatin 3 has only been targeted once and required the highest number of steps to synthesize (43 steps in the longest linear sequence and 88 total steps). Here, we report a concise total synthesis of bryostatin 3 using 22 steps in the longest linear sequence and 31 total steps through a highly convergent synthetic plan by the use of highly atom-economical and chemoselective transformations in which alkynes played a major role in reducing step count.


Assuntos
Produtos Biológicos/síntese química , Briostatinas/síntese química , Macrolídeos/síntese química , Alquinos/química , Produtos Biológicos/química , Briostatinas/química , Técnicas de Química Sintética , Macrolídeos/química
3.
Nat Commun ; 11(1): 2424, 2020 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-32415122

RESUMO

Lipid-like nanoparticles (LNPs) have potential as non-viral delivery systems for mRNA therapies. However, repeated administrations of LNPs may lead to accumulation of delivery materials and associated toxicity. To address this challenge, we have developed biodegradable lipids which improve LNPs clearance and reduce toxicity. We modify the backbone structure of Dlin-MC3-DMA by introducing alkyne and ester groups into the lipid tails. We evaluate the performance of these lipids when co-formulated with other amine containing lipid-like materials. We demonstrate that these formulations synergistically facilitate robust mRNA delivery with improved tolerability after single and repeated administrations. We further identify albumin-associated macropinocytosis and endocytosis as an ApoE-independent LNP cellular uptake pathway in the liver. Separately, the inclusion of alkyne lipids significantly increases membrane fusion to enhance mRNA release, leading to synergistic improvement of mRNA delivery. We believe that the rational design of LNPs with multiple amine-lipids increases the material space for mRNA delivery.


Assuntos
Sistemas de Liberação de Medicamentos , Lipídeos/química , Fígado/metabolismo , Nanopartículas/química , RNA Mensageiro/metabolismo , Receptores de Albumina/metabolismo , Alquinos/química , Aminas/química , Animais , Apolipoproteínas E/metabolismo , Materiais Biocompatíveis/química , Endossomos/metabolismo , Eritrócitos/metabolismo , Eritropoetina/química , Ésteres/química , Hepatócitos/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Simulação de Dinâmica Molecular , RNA Interferente Pequeno/metabolismo
4.
J Chromatogr A ; 1623: 461161, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32376015

RESUMO

Triacylglycerols (TAGs) containing less common fatty acids (FAs) were isolated from the seeds of three plants (Santalum album, Crepis foetida, and Leucas aspera). These FAs had allenic (laballenic acid, Lb) and acetylenic (crepenynic, C; ximenynic acids, Xi) bonds. TAGs were analyzed on reversed-phase and chiral columns. High-resolution tandem mass spectrometry identified TAGs by positive electrospray ionization (ESI+). Twenty-two molecular species of TAGs isolated from the seed oil of Santalum album were separated by RP-HPLC and chiral HPLC methods and identified by positive electrospray ionization tandem MS detection (ESI+-MS). Two major enantiomers, i.e., sn-OOLb and sn-LLLb (O represents oleic acid; and L represents linoleic acid), were synthesized from the appropriate phosphatidylcholines. This allowed the identification of enantiomers after separation by chiral chromatography by tandem mass spectrometry. Similarly, TAGs from the seeds of Crepis foetida, and Leucas aspera were analyzed by reversed-phase chromatography and identified by mass spectrometry. Four enantiomers (sn-OOC, sn-LLC, sn-OOXi, and sn-LLXi) were synthesized. A total of six and three enantiomers of TAGs containing crepenynic and ximenynic acids, respectively, were identified by chiral column analysis. The retention times of TAGs containing allenic and acetylenic bonds were always greater on the reversed-phase column than TAGs with the same number of carbon atoms and the same unsaturation (e.g., LLL versus LLLb). From the chiral column, the regioisomers and enantiomers were eluted in the order of symmetric-asymmetric-asymmetric (i.e., sn-OCO, sn-COO, and sn-OOC). Through tandem mass spectrometry, we were able to identify and distinguish regioisomer [DAG]+-type ions, i.e., [MNH4NH3RCOOH]+, that can be considered diagnostic. Unfortunately, enantiomers and TAGs with the same numbers of carbon atoms and the same unsaturation levels have identical mass spectra, such as LLL and LLLb.


Assuntos
Cromatografia Líquida de Alta Pressão , Ácidos Graxos/análise , Sementes/química , Espectrometria de Massas em Tandem , Triglicerídeos/química , Alquinos/análise , Alquinos/química , Cromatografia Líquida , Cromatografia de Fase Reversa , Ácidos Graxos/química , Ácido Linoleico/análise , Ácidos Oleicos/análise , Fosfatidilcolinas/química , Espectrometria de Massas por Ionização por Electrospray , Estereoisomerismo , Triglicerídeos/análise , Triglicerídeos/isolamento & purificação
5.
Chembiochem ; 21(15): 2214-2218, 2020 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-32187837

RESUMO

The reliable detection of transcription events through the quantification of the corresponding mRNA is of paramount importance for the diagnostics of infections and diseases. The quantification and localization analysis of the transcripts of a particular gene allows disease states to be characterized more directly compared to an analysis on the transcriptome wide level. This is particularly needed for the early detection of virus infections as now required for emergent viral diseases, e. g. Covid-19. In situ mRNA analysis, however, is a formidable challenge and currently performed with sets of single-fluorophore-containing oligonucleotide probes that hybridize to the mRNA in question. Often a large number of probe strands (>30) are required to get a reliable signal. The more oligonucleotide probes are used, however, the higher the potential off-target binding effects that create background noise. Here, we used click chemistry and alkyne-modified DNA oligonucleotides to prepare multiple-fluorophore-containing probes. We found that these multiple-dye probes allow reliable detection and direct visualization of mRNA with only a very small number (5-10) of probe strands. The new method enabled the in situ detection of viral transcripts as early as 4 hours after infection.


Assuntos
Química Click/métodos , Diagnóstico Precoce , Hibridização in Situ Fluorescente/métodos , Sondas de Oligonucleotídeos/química , RNA Mensageiro/análise , RNA Viral/análise , Alquinos/química , Betacoronavirus/genética , Infecções por Coronavirus/diagnóstico , Humanos , Oligodesoxirribonucleotídeos/química , Pandemias , Pneumonia Viral/diagnóstico
6.
Phys Chem Chem Phys ; 22(9): 4875-4879, 2020 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-32072999

RESUMO

Structural studies on proteins directly in their native environment are required for a comprehensive understanding of their function. Electron paramagnetic resonance (EPR) spectroscopy and in particular double electron-electron resonance (DEER) distance determination are suited to investigate spin-labeled proteins directly in the cell. The combination of intracellular bioorthogonal labeling with in-cell DEER measurements does not require additional purification or delivery steps of spin-labeled protein to the cells. In this study, we express eGFP in E. coli and use copper-catalyzed azide-alkyne cycloaddition (CuAAC) for the site-directed spin labeling of the protein in vivo, followed by in-cell EPR distance determination. Inter-spin distance measurements of spin-labeled eGFP agree with in vitro measurements and calculations based on the rotamer library of the spin label.


Assuntos
Espectroscopia de Ressonância de Spin Eletrônica , Escherichia coli/metabolismo , Proteínas de Fluorescência Verde/química , Alquinos/química , Azidas/química , Catálise , Cobre/química , Reação de Cicloadição , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Óxidos de Nitrogênio/química , Marcadores de Spin
7.
Chem Commun (Camb) ; 56(20): 3039-3042, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-32048637

RESUMO

We report synthesis and enzymatic assays on human histone lysine methyltransferase catalysed methylation of histones that possess lysine and its geometrically constrained analogues containing rigid (E)-alkene (KE), (Z)-alkene (KZ) and alkyne (Kyne) moieties. Methyltransferases G9a and GLP do have a capacity to catalyse methylation in the order K ≫ KE > KZ ∼ Kyne, whereas monomethyltransferase SETD8 catalyses only methylation of K and KE.


Assuntos
Histona-Lisina N-Metiltransferase/metabolismo , Lisina/metabolismo , Alcenos/química , Alcenos/metabolismo , Alquinos/química , Alquinos/metabolismo , Biocatálise , Humanos , Lisina/análogos & derivados , Lisina/química , Metilação , Conformação Molecular
8.
Dalton Trans ; 49(8): 2407-2411, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-32022087

RESUMO

Enynes are important synthetic intermediates that are also found in a variety of natural products and other biologically relevant molecules. The most atom economical synthetic route to enynes is via the direct coupling of readily available terminal alkyne precursors. Towards this goal, we demonstrate the formation of 1,3-enynes from terminal alkynes facilitated by a reduced ZrIV/Co-I heterobimetallic complex. An intermediate is trapped as a tBuNC adduct, revealing that bimetallic activation of the terminal C-H bond of the alkyne is an essential mechanistic step.


Assuntos
Alcenos/química , Alquinos/química , Cobalto/química , Zircônio/química , Catálise , Dimerização , Estrutura Molecular , Estereoisomerismo
9.
Org Biomol Chem ; 18(10): 1957-1967, 2020 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-32101244

RESUMO

1,4- and 1,5-Disubstituted triazole amino acid monomers have gained increasing interest among peptidic foldamers, as they are easily prepared via Cu- and Ru-catalyzed click reactions, with the potential for side chain variation. While the latter is key to their applicability, the synthesis and structural properties of the chiral mono- or disubstituted triazole amino acids have only been partially addressed. We here present the synthesis of all eight possible chiral derivatives of a triazole monomer prepared via a ruthenium-catalyzed azide alkyne cycloaddition (RuAAC). To evaluate the conformational properties of the individual building units, a systematic quantum chemical study was performed on all monomers, indicating their capacity to form several low energy conformers. This feature may be used to effect structural diversity when the monomers are inserted into various peptide sequences. We envisage that these results will facilitate new applications for these artificial oligomeric compounds in diverse areas, ranging from pharmaceutics to biotechnology.


Assuntos
Peptidomiméticos/síntese química , Triazóis/síntese química , Alquinos/química , Azidas/química , Química Click , Reação de Cicloadição , Modelos Moleculares , Polimerização , Polímeros/síntese química , Teoria Quântica , Estereoisomerismo , Termodinâmica
10.
Chem Commun (Camb) ; 56(13): 1988-1991, 2020 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-31960852

RESUMO

Kinugasa reactions hold potential for bioorthogonal chemistry in that the reagents can be biocompatible. Unlike other bioorthogonal reaction products, ß-lactams are potentially reactive, which can be useful for synthesizing new biomaterials. A limiting factor for applications consists of slow reaction rates. Herein, we report an optimized aqueous copper(i)-catalyzed alkyne-nitrone cycloaddition involving rearrangement (CuANCR) with rate accelerations made possible by the use of surfactant micelles. We have investigated the factors that accelerate the aqueous CuANCR reaction and demonstrate enhanced modification of a model membrane-associated peptide. We discovered that lipids/surfactants and alkyne structure have a significant impact on the reaction rate, with biological lipids and electron-poor alkynes showing greater reactivity. These new findings have implications for the use of CuANCR for modifying integral membrane proteins as well as live cell labelling and other bioorthogonal applications.


Assuntos
Reação de Cicloadição/métodos , Lipídeos/química , Tensoativos/química , Água/química , Alquinos/química , Azidas/química , Catálise , Cobre/química , Proteínas de Membrana/química
11.
Nat Commun ; 11(1): 81, 2020 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-31900403

RESUMO

Live-cell Raman imaging based on bioorthogonal Raman probes with distinct signals in the cellular Raman-silent region (1800-2800 cm-1) has attracted great interest in recent years. We report here a class of water-soluble and biocompatible polydiacetylenes with intrinsic ultrastrong alkyne Raman signals that locate in this region for organelle-targeting live-cell Raman imaging. Using a host-guest topochemical polymerization strategy, we have synthesized a water-soluble and functionalizable master polydiacetylene, namely poly(deca-4,6-diynedioic acid) (PDDA), which possesses significantly enhanced (up to ~104 fold) alkyne vibration compared to conventional alkyne Raman probes. In addition, PDDA can be used as a general platform for multi-functional ultrastrong Raman probes. We achieve high quality live-cell stimulated Raman scattering imaging on the basis of modified PDDA. The polydiacetylene-based Raman probes represent ultrastrong intrinsic Raman imaging agents in the Raman-silent region (without any Raman enhancer), and the flexible functionalization of this material holds great promise for its potential diverse applications.


Assuntos
Células/citologia , Imagem Molecular/métodos , Sondas Moleculares/química , Polímero Poliacetilênico/química , Análise Espectral Raman/métodos , Alquinos/química , Células/química , Células HeLa , Humanos , Imagem Molecular/instrumentação , Sondas Moleculares/síntese química , Polímero Poliacetilênico/síntese química , Análise Espectral Raman/instrumentação
12.
Molecules ; 25(1)2020 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-31947731

RESUMO

The original goal of this research was to study stereochemistry of selenium dihalides addition to cycloalkenes and properties of obtained products. Remarkable alkene-to-alkene and alkene-to-alkyne transfer reactions of selenium dibromide and PhSeBr were discovered during this research. The adducts of selenium dibromide with alkenes or cycloalkenes easily exchange SeBr2 with other unsaturated compounds, including acetylenes, at room temperature, in acetonitrile. Similar alkene-to-alkene and alkene-to-alkyne transfer reactions of the PhSeBr adducts with alkenes or cycloalkenes take place. The supposed reaction pathway includes the selenium group transfer from seleniranium species to alkenes or alkynes. It was found that the efficient SeBr2 and PhSeBr transfer reagents are Se(CH2CH2Br)2 and PhSeCH2CH2Br, which liberate ethylene, leading to a shift in equilibrium. The regioselective and stereoselective synthesis of bis(E-2-bromovinyl) selenides and unsymmetrical E-2-bromovinyl selenides was developed based on the SeBr2 and PhSeBr transfer reactions which proceeded with higher selectivity compared to analogous addition reactions of SeBr2 and PhSeBr to alkynes under the same conditions.


Assuntos
Alcenos/química , Alquinos/química , Brometos/química , Cicloparafinas/química , Compostos de Selênio/química , Catálise , Ciclização
13.
Org Biomol Chem ; 18(8): 1504-1521, 2020 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-31971216

RESUMO

The direct ß-C(sp2)-H functionalization of enamides has attracted increasing attention among the chemical community, due to the diverse biological and pharmaceutical activities of enamides. This review is focused on the recent advances in the direct ß-C(sp2)-H functionalization of enamides, mainly including arylation, alkenylation, alkynylation, alkylation, acylation, sulfonylation, phosphorylation, and others. Additionally, mechanistic features of these transformations are also discussed.


Assuntos
Amidas/química , Acilação , Alcenos/química , Alquilação , Alquinos/química , Fosforilação , Compostos de Enxofre/química
14.
Macromol Rapid Commun ; 41(4): e1900457, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31971647

RESUMO

In this study, a supramolecular hydrogel formed by incorporating the 2,6-bis(1,2,3-triazol-4-yl)-pyridine (btp) ligand in the backbone of a polymer prepared by copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) "click" polyaddition reaction of 2,6-diethynylpyridine and diazido-poly(ethylene glycol) is reported. The hydrogelation is selectively triggered by the addition of Ni2+ ions to aqueous copolymer solutions. The gelation and rheological properties could be tuned by the change of metal to ligand ratio and polymer concentration. Interestingly, the hydrogel exhibits a fast (within 2 min) and excellent repeatable autonomic healing capacity without external stimuli. This self-healing behavior may find potential applications for the repairing of metal coatings, in the future.


Assuntos
Hidrogéis/química , Níquel/química , Polímeros/química , Piridinas/química , Triazóis/química , Alquinos/química , Azidas/química , Reação de Cicloadição , Hidrogéis/análise , Hidrogéis/síntese química , Ligantes , Ciência dos Materiais , Polietilenoglicóis/química , Polímeros/análise , Polímeros/síntese química , Reologia
15.
Chemistry ; 26(20): 4576-4582, 2020 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-31903629

RESUMO

Light-up bioorthogonal probes have attracted increasing attention recently due to their capability to directly image diverse biomolecules in living cells without washing steps. The development of bioorthogonal probes with excellent fluorescent properties suitable for in vivo imaging, such as long excitation/emission wavelength, high fluorescence turn-on ratio, and deep penetration, has been rarely reported. Herein, a series of azide-based light-up bioorthogonal probes with tunable colors based on a weak fluorescent 8-aminoquinoline (AQ) scaffold were designed and synthesized. The azido quinoline derivatives are able to induce large fluorescence enhancement (up to 1352-fold) after click reaction with alkynes. In addition, the probes could be engineered to exhibit excellent two-photon properties (δ=542 GM at 780 nm) after further introducing different styryl groups into the AQ scaffold. Subsequent detailed bioimaging experiments demonstrated that these versatile probes can be successfully used for live cell/zebrafish imaging without washing steps. Further in vivo two-photon imaging experiments demonstrated that these light-up biorthogonal probe outperformed conventional fluorophores, for example, high signal-to-noise ratio and deep tissue penetration. The design strategy reported in this study is a useful approach to realize diverse high-performance biorthogonal light-up probes for in vivo studying.


Assuntos
Alquinos/química , Azidas/química , Corantes Fluorescentes/química , Fluorescência , Humanos , Fótons
16.
Biomater Sci ; 8(1): 405-412, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31729512

RESUMO

Hydrogels based on hyaluronic acid (HA) exhibit great potential as tissue engineering (TE) scaffolds as a consequence of their unique biological features. Herein, we examine how the advantages of two natural polymers (i.e. HA and alginate) are combined with the efficiency and rapid nature of the thiol-yne click chemistry reaction to obtain biocompatible matrices with tailored properties. Our injectable click-hydrogels revealed excellent mechanical performance, long-term stability, high cytocompatibility and adequate stiffness for the targeted application. This simple approach yielded HA hydrogels with characteristics that make them suitable for applications as 3D scaffolds to support and promote soft tissue regeneration.


Assuntos
Alginatos/química , Alquinos/química , Ácido Hialurônico/química , Hidrogéis/química , Compostos de Sulfidrila/química , Engenharia Tecidual , Tecidos Suporte/química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Química Click , Força Compressiva , Humanos , Hidrogéis/farmacologia , Reologia
17.
ACS Appl Mater Interfaces ; 12(1): 1588-1596, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31840506

RESUMO

Antifouling surfaces with optimized conformation and compositional heterogeneities are presented with the goal of improving the efficacy of surface protection. The approach exploits the adhesive group (thiol or catechol chain end) to anchor asymmetric polymer brushes (APBs) bearing amphiphilic side chains with synergistic nonfouling and fouling-release abilities onto the surface. The conformation of the APB surface is close to the fencelike structure, which mimics lubricating protein lubricin, endowing the surface with capacity of enhanced protection and antiadhesivity, even facing the high compression of fouling. By utilizing a poly(Br-acrylate-alkyne) macroagent comprising alkynyl and 2-bromopropionate groups, we prepared a series of APB surfaces based on polyacrylate-g-poly(ethylene oxide)/poly(pentafluorophenyl methacrylate) (PA-g-PEO/PPFMA) APBs to explore the influence of the content of the fluorinated segment and bioinspired topological polymer chemistry on their antifouling performance. The APB surfaces can not only provide compositional heterogeneities of PEO and fluorinated segments in each side chain but also give a high surface coverage because of the characteristic of high grafting density of macromolecular brushes. It was found for the first time, as far as we are aware, the fencelike APB surface shows excellent antifouling performance with less protein adsorption (up to 91% off) and cell adhesion (up to 84% off) in comparison with the controlled substrate under relatively long incubation time.


Assuntos
Adesivos/farmacologia , Biomimética , Adesão Celular/efeitos dos fármacos , Propriedades de Superfície/efeitos dos fármacos , Adesivos/química , Adsorção/efeitos dos fármacos , Alquinos/química , Catecóis/química , Catecóis/farmacologia , Metacrilatos/química , Metacrilatos/farmacologia , Conformação Molecular , Polietilenoglicóis/química , Polietilenoglicóis/farmacologia , Polímeros/química , Polímeros/farmacologia , Compostos de Sulfidrila/química , Compostos de Sulfidrila/farmacologia
18.
Macromol Rapid Commun ; 41(4): e1900598, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31880033

RESUMO

An efficient bimolecular ring-closure method is developed to prepare the well-defined cyclic polynorbornenes by combining the living ring-opening metathesis polymerization (ROMP) with the self-accelerating double strain-promoted azide-alkyne cycloaddition (DSPAAC) reaction. In this method, ROMP is used to synthesize the well-defined linear polynorbornenes with both azide terminals by virtue of a N-hydroxysuccinimide-ester-functionalized Grubbs initiator following the modification of polymer end groups. DSPAAC click reaction is then used to ring-close the linear polymer precursors and prepare the corresponding well-defined cyclic polynorbornenes using the sym-dibenzo-1,5-cyclooctadiene-3,7-diyne (DIBOD) as small linkers. The self-accelerating DSPAAC ring-closing reaction facilitates this method to efficiently prepare pure cyclic polynorbornenes in the presence of a molar excess of DIBOD small linkers to the linear polynorbornene precursors. This is the first report to prepare well-defined polynorbornenes with cyclic topology based on the ring-closure strategy for cyclic polymers.


Assuntos
Reação de Cicloadição/métodos , Plásticos/síntese química , Polímeros/síntese química , Alquinos/química , Azidas/química , Química Click , Plásticos/análise , Plásticos/química , Polimerização , Polímeros/química
19.
Macromol Rapid Commun ; 41(4): e1900468, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31880037

RESUMO

Catalytic dehydropolymerization of halogen-functionalized phosphine-boranes (4-X-C6 H4 )PH2 ⋅BH3 (1a: X = Br, 1b: X = I) with [CpFe(CO)2 (OTf)] at 100 °C provides convenient access to halogen-functionalized polyphosphinoboranes [(4-X-C6 H4 )PH-BH2 ]n (2a: X = Br, 2b: X = I). These polymers are useful precursors for post-polymerization functionalization, which is demonstrated by Sonogashira coupling under mild conditions to yield the alkynyl-functionalized polyphosphinoborane [(4-PhCC-C6 H4 )PH-BH2 ]n (3).


Assuntos
Boranos/química , Halogênios/química , Fosfinas/química , Polímeros/química , Polímeros/síntese química , Alquinos/química , Catálise , Polimerização
20.
J Vis Exp ; (154)2019 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-31885378

RESUMO

Benzannulation reactions represent an effective protocol to transform acyclic building blocks into structurally varied benzene skeletons. Despite classical and recent approaches toward functionalized benzenes, in water metal-free methods remains a challenge and represents an opportunity to expand even more the set of tools used to synthesize polysubstituted benzene compounds. This protocol describes an operationally simple experimental setup to explore the benzannulation of α,ß-unsaturated compounds and alkynes to afford unprecedented functionalized benzene rings in high yields. Ammonium persulfate is the reagent of choice and brings notable advantages as stability and easy handling. Moreover, the use of water as a solvent and the absence of metals impart more sustainability to the method. A modified workup procedure that avoids the use of drying agents also adds convenience to the protocol. The purification of the products is performed using only a plug of silica. The substrate scope is currently limited to terminal alkynes and α,ß-unsaturated aliphatic compounds.


Assuntos
Alquinos/química , Benzeno/síntese química , Sulfatos/química , Água/química , Benzeno/química , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Espectroscopia de Prótons por Ressonância Magnética , Solventes
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