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1.
J Oleo Sci ; 69(8): 871-882, 2020 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-32641614

RESUMO

In this study, an N-heterocyclic carbene (NHC)-based metal coordinate surfactant (MCS), NHC-Au-MCS, in which the NHC framework afforded the bonding of the Au(I) at the linkage of the hydrophilic and hydrophobic moieties, was synthesized. The structure of NHC-Au-MCS was confirmed by 1H and 13C NMR spectroscopic measurements together with elemental analysis. Matrix-assisted laser desorption/ionization (MALDI), laser desorption/ionization (LDI), and electrospray ionization mass spectrometry (ESI-MS) indicated the distinct reactivity of NHC-Au-MCS, such as the exchange of Br to Cl and the formation of a cationic Au complex, where the two NHC ligands were coordinated to an Au(I) center upon laser activation. The surface tension and dynamic light scattering (DLS) measurements revealed that the coordination of Au(I) to NHC reduced the critical micelle concentration (CMC) of NHC-Au-MCS (1.3×10-5 M), which resulted in the formation of micelles at concentrations higher than the CMC in water. We also confirmed that the surface-active Au(I) complex of NHC-Au-MCS catalyzed the hydration of 1-dodecyne to 2-dodecanone in water in the absence of an organic solvent. On the basis of the detailed mechanistic investigations regarding the reactivity of NHC-Au-MCS, we revealed that NHC-Au-MCS partially translated into Au nanoparticles (AuNPs), which facilitated alkyne hydration. These mechanistic studies were supported by UV-vis measurements, transmission electron microscopy (TEM), and LDI-MS.


Assuntos
Alquinos/química , Ouro/química , Compostos Heterocíclicos/síntese química , Nanopartículas Metálicas/química , Metano/análogos & derivados , Tensoativos/síntese química , Catálise , Compostos Heterocíclicos/química , Hidrogenação , Interações Hidrofóbicas e Hidrofílicas , Metano/síntese química , Metano/química , Micelas , Tensoativos/química , Água
2.
Top Curr Chem (Cham) ; 378(3): 39, 2020 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-32367181

RESUMO

During the last decade, organometallic, coordination, and catalytic chemistry of the three-dimensional metals such as copper (Cu) has been greatly affected by the emergence of nitrogen heterocyclic carbene (NHC) complexes. The NHCs, and in particular the mononuclear CuI-based ones, have been proven vastly useful in several applications such as in biosynthesis, catalysis, photochemistry, etc. This review tries to thoroughly describe a series of mononuclear CuI NHC complexes and their subcategories such as heteroleptics, and bidentate and tridentate heteroatom complexes, and give some detailed insights on their development, emergence, and applications. A brief outlook is also disclosed to enable other researchers to further develop a platform for future advances and studies in the field of CuI-based NHCs.


Assuntos
Complexos de Coordenação/química , Cobre/química , Compostos Heterocíclicos/química , Metano/análogos & derivados , Nitrogênio/química , Complexos de Coordenação/síntese química , Metano/química , Estrutura Molecular
3.
Chimia (Aarau) ; 74(4): 278-284, 2020 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-32331547

RESUMO

N-Heterocyclic carbenes (NHCs) are the ligands of choice in a large variety of transformations entailing different transition metals. However, the number and variety of chiral NHCs suitable as stereo-controlling ligands in asymmetric catalysis remains limited. Herein we highlight the introduction of a modular NHC ligand family, consisting of a chiral version of the widely used IPr ligand. These chiral NHC ligands were applied in the nickel-catalyzed enantioselective C-H functionalization of N-heterocycles. Nickel-NHC catalysis unlocked the stereoselective C-H annulation of 2- and 4-pyridones, delivering fused bicyclic compounds found in many biologically active compounds. Applying a bulky, yet flexible ligand scaffold enabled the highly enantioselective C-H functionalization of pyridones under mild conditions. The introduction of a bulky chiral SIPr analogue enabled the nickel-catalyzed enantioselective C-H functionalization of indoles, yielding valuable tetrahydropyridoindoles. Additionally, pyrrolopyridines, pyrrolopyrimidines and pyrroles were efficiently functionalized, delivering chiral annulated azoles.


Assuntos
Metano/análogos & derivados , Catálise , Compostos Heterocíclicos , Ligantes , Metano/química , Níquel , Estereoisomerismo
4.
Science ; 367(6482): 1091-1097, 2020 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-32139536

RESUMO

Many disease pathologies can be understood through the elucidation of localized biomolecular networks, or microenvironments. To this end, enzymatic proximity labeling platforms are broadly applied for mapping the wider spatial relationships in subcellular architectures. However, technologies that can map microenvironments with higher precision have long been sought. Here, we describe a microenvironment-mapping platform that exploits photocatalytic carbene generation to selectively identify protein-protein interactions on cell membranes, an approach we term MicroMap (µMap). By using a photocatalyst-antibody conjugate to spatially localize carbene generation, we demonstrate selective labeling of antibody binding targets and their microenvironment protein neighbors. This technique identified the constituent proteins of the programmed-death ligand 1 (PD-L1) microenvironment in live lymphocytes and selectively labeled within an immunosynaptic junction.


Assuntos
Antígeno B7-H1/metabolismo , Membrana Celular/metabolismo , Microambiente Celular , Linfócitos/metabolismo , Mapeamento de Interação de Proteínas/métodos , Mapas de Interação de Proteínas , Catálise , Membrana Celular/efeitos da radiação , Transferência de Energia , Humanos , Células Jurkat , Linfócitos/efeitos da radiação , Metano/análogos & derivados , Metano/química , Metano/efeitos da radiação , Processos Fotoquímicos , Raios Ultravioleta
5.
Mikrochim Acta ; 187(4): 233, 2020 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-32180017

RESUMO

Two-dimensional (2D) COFs have been successfully applied for various applications, such as capillary electrochromatography (CEC). Compared with 2D COFs, three-dimensional (3D) COFs have higher surface area and lower density, which should have superior potential as the separation medium in CEC. However, the 3D COFs on the inner wall of capillary is hard to fabricate in situ. Up to date, the application of 3D COFs in open-tubular capillary electrochromatography (OT-CEC) is still considered a challenge. For the first time the COF-300-coated capillary was prepared by in situ growth (COF-300 was made from terephthalaldehyde and tetra-(4-anilyl)-methane) on OT-CEC. Benzene, methylbenzene, styrene, ethylbenzene, naphthalene, 1-methylnaphthalene, and propylbenzene were used to evaluate the performance of the COF-300-coated capillary by OT-CEC. For three consecutive runs, the intraday relative standard deviations (RSDs) of migration time and peak areas were 0.1-0.4% and 2.5-8.3%, respectively. The interday RSDs of migration time and peak areas were 0.2-0.5% and 1.0-10.8%, respectively. Five groups of aromatic co mpounds were used to further study the separation mechanism, which indicated that hydrophobic interaction and size selection interaction are the main factors. It should be noted that the COF-300-coated capillary can be used for more than 140 runs with no observable changes of the separation efficiency. Graphical abstract The 3D COF-300-coated capillary was prepared by in situ growth for OT-CEC. Six groups of aromatic compounds were separated by 3D COF-300-coated capillary. Size selection and hydrophobic interaction affect the migration time of analytes.


Assuntos
Aldeídos/química , Hidrocarbonetos Aromáticos/isolamento & purificação , Metano/química , Eletrocromatografia Capilar , Hidrocarbonetos Aromáticos/química , Metano/análogos & derivados
6.
Environ Sci Technol ; 54(4): 2182-2191, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-32020793

RESUMO

Potable reuse of wastewater is expanding, and ozonation for water reuse is becoming more common, either as a preoxidant before membranes or as part of ozone/biological activated carbon (O3/BAC) systems. However, previous research has demonstrated that ozone drastically increases the formation potential of genotoxic halonitromethanes (HNMs), including during O3/BAC. Chloropicrin, the most common HNM, is synthesized by chlorinating nitromethane, suggesting that nitromethane may be the immediate precursor of chloropicrin, although nitromethane is unlikely to occur naturally in wastewater. We hypothesized that wastewater ozonation forms nitromethane, which would be the key intermediate toward HNMs. Ozonation of wastewater effluent was shown to form abundant nitromethane, which explained the majority (in one case, all) of subsequent chloropicrin formation. Next, we investigated a suspected category of nitromethane precursor: stimulant drugs, such as ephedrine and methamphetamine, and certain antidepressants. These drugs all feature N-methylamine functional groups, and certain N-alkylamines have been shown to produce primary nitroalkanes upon ozonation. Ozonation of N-methylamine drugs ubiquitously formed nitromethane, typically at >50% yield. Subsequent chlorination converted nitromethane to chloropicrin. The reaction mechanism was investigated to understand the variation in nitromethane yield between different precursors. These results suggest that nitromethane fate during reuse and nitromethane control should be investigated.


Assuntos
Ozônio , Poluentes Químicos da Água , Purificação da Água , Metano/análogos & derivados , Metilaminas , Nitroparafinas , Águas Residuárias
7.
Dalton Trans ; 49(8): 2505-2516, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-32022055

RESUMO

In this study, we designed and synthesized four novel multi-nuclear silver complexes (1-4) coordinated with pyrazole- or pyridine-functionalized N-heterocyclic carbene (NHC) ligands. The crystal structures of the silver-NHC complexes were confirmed by X-ray diffraction analysis. In vitro assays showed that the silver-NHC complexes effectively killed a broad range of cancer cells after short-term drug exposure, serving as fast-acting cytotoxic agents. Of note, in cisplatin-resistant A549 cancer cells, the silver complexes were not cross-resistant with the clinically used cisplatin agent. Detailed mechanistic studies revealed that complex 2 triggered caspase-independent cell necrosis associated with intracellular reactive oxygen species (ROS) production and mitochondrial membrane potential (MMP) depletion. By exploiting a facile nano-assembly process, silver-NHC complexes 1, 2 and 4 were successfully integrated into the hydrophobic cores of amphiphilic matrices (DSPE-PEG2K), enabling systemic injection. The silver complex-loaded nanotherapeutics (1-NPs, 2-NPs, and 4-NPs) showed high safety margins with reduced systemic drug toxicities relative to cisplatin in animals. Furthermore, in a xenograft model of human colorectal cancer, the administration of the nanotherapeutics resulted in a marked inhibition of tumor progression.


Assuntos
Antineoplásicos/farmacologia , Neoplasias do Colo/tratamento farmacológico , Metano/análogos & derivados , Nanopartículas/química , Pirazóis/química , Piridinas/química , Prata/química , Células A549 , Animais , Apoptose , Proliferação de Células , Neoplasias do Colo/patologia , Compostos Heterocíclicos/farmacologia , Humanos , Metano/química , Camundongos , Estrutura Molecular , Nanopartículas/administração & dosagem , Relação Estrutura-Atividade , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto
8.
Inorg Chem ; 59(5): 3312-3320, 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32049516

RESUMO

We carried out a detailed theoretical study on the mechanism of the carbene ligand substitution by cysteine and selenocysteine residues in an Au(I) bis-N-heterocyclic carbene complex in order to model the initial stages of the mechanism of action of this promising class of antitumor metallodrug. Both neutral and deprotonated capped Cys and Sec species were considered as possible nucleophiles in the ligand exchange reaction on the metal center to model the corresponding protein side chains. Energies and geometric structures of the possible transition states and reactant- and product-adducts involved in the substitution process have been calculated using density functional theory and local MP2. Reaction and activation enthalpies and free energies have been evaluated and indicate a slightly exothermic and exergonic process with reasonably low barriers, 21.3 and 19.6 kcal mol-1, respectively, for capped Cys and Sec, in good agreement with the experimental data available for the reaction with free amino acids. The results suggest a mechanism for the ligand exchange reaction involving an anionic thiolate or selenothiolate species coupled to an explicit proton transfer to the leaving carbene from the acidic component of the buffer. The presence of a buffer is necessary both in in vitro experiments and under physiological conditions, and its proton reservoir behavior reveals the importance of the environmental effects in carbene substitution by biological nucleophiles.


Assuntos
Antineoplásicos/química , Cisteína/química , Ouro/química , Compostos Heterocíclicos/química , Metano/análogos & derivados , Antineoplásicos/síntese química , Cisteína/análogos & derivados , Teoria da Densidade Funcional , Metano/química , Estrutura Molecular
9.
Inorg Chem ; 59(5): 3281-3289, 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32073260

RESUMO

Metal complexes provide a versatile platform to develop novel anticancer pharmacophores, and they form stable compounds with N-heterocyclic carbene (NHC) ligands, some of which have been shown to inhibit the cancer-related selenoenzyme thioredoxin reductase (TrxR). To expand a library of isostructural NHC complexes, we report here the preparation of RhIII- and IrIII(Cp*)(NHC)Cl2 (Cp* = η5-pentamethylcyclopentadienyl) compounds and comparison of their properties to the RuII- and OsII(cym) analogues (cym = η6-p-cymene). Like the RuII- and OsII(cym) complexes, the RhIII- and IrIII(Cp*) derivatives exhibit cytotoxic activity with half maximal inhibitory concentration (IC50) values in the low micromolar range against a set of four human cancer cell lines. In studies on the uptake and localization of the compounds in cancer cells by X-ray fluorescence microscopy, the Ru and Os derivatives were shown to accumulate in the cytoplasmic region of treated cells. In an attempt to tie the localization of the compounds to the inhibition of the tentative target TrxR, it was surprisingly found that only the Rh complexes showed significant inhibitory activity at IC50 values of ∼1 µM, independent of the substituents on the NHC ligand. This indicates that, although TrxR may be a potential target for anticancer metal complexes, it is unlikely the main target or the sole target for the Ru, Os, and Ir compounds described here, and other targets should be considered. In contrast, Rh(Cp*)(NHC)Cl2 complexes may be a scaffold for the development of TrxR inhibitors.


Assuntos
Antineoplásicos/farmacologia , Complexos de Coordenação/farmacologia , Inibidores Enzimáticos/farmacologia , Tiorredoxina Dissulfeto Redutase/antagonistas & inibidores , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Compostos Heterocíclicos/química , Compostos Heterocíclicos/farmacologia , Humanos , Ligantes , Metais Pesados/química , Metais Pesados/farmacologia , Metano/análogos & derivados , Metano/química , Metano/farmacologia , Conformação Molecular , Relação Estrutura-Atividade , Tiorredoxina Dissulfeto Redutase/metabolismo
10.
Chem Soc Rev ; 49(3): 908-950, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31958107

RESUMO

Donor and donor-donor carbenes are two important kinds of carbenes, which have experienced tremendous growth in the past two decades. This review provides a comprehensive overview of the recent development of donor and donor-donor carbene chemistry. The development of this chemistry offers efficient protocols to construct a wide variety of C-C and C-X bonds in organic synthesis. This review is organized based on the different types of carbene precursors, including diazo compounds, hydrazones, enynones, cycloheptatrienes and cyclopropenes. The typical transformations, the reaction mechanisms, as well as their subsequent applications in the synthesis of complex natural products and bioactive molecules are discussed. Due to the rapidly increasing interest in this area, we believe that this review will provide a timely and comprehensive discussion of recent progress in donor and donor-donor carbene chemistry.


Assuntos
Metano/análogos & derivados , Compostos Azo/química , Catálise , Ciclopropanos/química , Hidrazonas/química , Metais/química , Metano/síntese química , Estrutura Molecular , Estereoisomerismo
11.
Chem Pharm Bull (Tokyo) ; 68(1): 1-33, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31902899

RESUMO

Novel reactions using hetero-heavy atoms (P, S, Si, Se, and Sn) were developed and applied to the synthesis of biofunctional molecules and some medicine-candidates, in which the following items are covered. 1) Development of introduction of C1-unit using cyanophosphates (CPs). 2) Carbene-generation under neutral condition from CPs and its application to organic synthesis. 3) [3,3]Sigmatropic rearrangement-ring expansion reactions of medium-sized cyclic thionocarbonates containing a sulfur atom and their application to natural product synthesis. 4) Stereoselective synthesis of novel ß-imidazole C-nucleosides via diazafulvene intermediates and their application to investigating ribozyme reaction mechanism. 5) Developments of novel histamine H3- and H4-receptor ligands using new synthetic methods involving Se or Sn atoms.


Assuntos
Produtos Biológicos/química , Metais/química , Animais , Produtos Biológicos/síntese química , Proliferação de Células/efeitos dos fármacos , Agonistas dos Receptores Histamínicos/síntese química , Agonistas dos Receptores Histamínicos/química , Agonistas dos Receptores Histamínicos/farmacologia , Antagonistas dos Receptores Histamínicos/síntese química , Antagonistas dos Receptores Histamínicos/química , Antagonistas dos Receptores Histamínicos/farmacologia , Humanos , Metano/análogos & derivados , Metano/química , Metano/metabolismo , Nitrilos/química , Nucleosídeos/síntese química , Nucleosídeos/química
12.
Proc Natl Acad Sci U S A ; 117(3): 1419-1428, 2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31896585

RESUMO

By constructing an in vivo-assembled, catalytically proficient peroxidase, C45, we have recently demonstrated the catalytic potential of simple, de novo-designed heme proteins. Here, we show that C45's enzymatic activity extends to the efficient and stereoselective intermolecular transfer of carbenes to olefins, heterocycles, aldehydes, and amines. Not only is this a report of carbene transferase activity in a completely de novo protein, but also of enzyme-catalyzed ring expansion of aromatic heterocycles via carbene transfer by any enzyme.


Assuntos
Biocatálise , Proteínas de Escherichia coli/química , Metano/análogos & derivados , Peroxidases/química , Aldeídos/química , Alcenos/química , Aminas/química , Escherichia coli , Proteínas de Escherichia coli/metabolismo , Metano/química , Peroxidases/metabolismo , Especificidade por Substrato
13.
Molecules ; 25(1)2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31935971

RESUMO

The use of centroids of localized orbitals as a method to derive oxidation states (OS) from first-principles is critically analyzed. We explore the performance of the closest-atom distance criterion to assign electrons for a number of challenging systems, including high-valent transition metal compounds, π-adducts, and transition metal (TM) carbenes. Here, we also introduce a mixed approach that combines the position of the centroids with Bader's atomic basins as an alternative criterion for electron assignment. The closest-atom criterion performs reasonably well for the challenging systems, but wrongly considers O-H and N-H bonds as hydrides. The new criterion fixes this problem, but underperforms in the case of TM carbenes. Moreover, the OS assignment in dubious cases exhibit undesirable dependence on the particular choice for orbital localization.


Assuntos
Modelos Teóricos , Oxirredução , Metano/análogos & derivados , Metano/química , Modelos Moleculares , Prótons , Teoria Quântica
14.
Chem Rev ; 120(4): 1981-2048, 2020 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-31967451

RESUMO

In this contribution, we provide a comprehensive overview of C-H activation methods promoted by NHC-transition metal complexes, covering the literature since 2002 (the year of the first report on metal-NHC-catalyzed C-H activation) through June 2019, focusing on both NHC ligands and C-H activation methods. This review covers C-H activation reactions catalyzed by group 8 to 11 NHC-metal complexes. Through discussing the role of NHC ligands in promoting challenging C-H activation methods, the reader is provided with an overview of this important area and its crucial role in forging carbon-carbon and carbon-heteroatom bonds by directly engaging ubiquitous C-H bonds.


Assuntos
Técnicas de Química Sintética/métodos , Compostos Heterocíclicos/química , Metano/análogos & derivados , Compostos Organometálicos/química , Paládio/química , Compostos Heterocíclicos/síntese química , Imidazóis/química , Metano/química , Oxazóis/química , Tiazóis/química
15.
Chemistry ; 26(1): 33-48, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31599057

RESUMO

The ability to modify biologically active molecules such as antibodies with drug molecules, fluorophores or radionuclides is crucial in drug discovery and target identification. Classic chemistry used for protein functionalisation relies almost exclusively on thermochemically mediated reactions. Our recent experiments have begun to explore the use of photochemistry to effect rapid and efficient protein functionalisation. This article introduces some of the principles and objectives of using photochemically activated reagents for protein ligation. The concept of simultaneous photoradiosynthesis of radiolabelled antibodies for use in molecular imaging is introduced as a working example. Notably, the goal of producing functionalised proteins in the absence of pre-association (non-covalent ligand-protein binding) introduces requirements that are distinct from the more regular use of photoactive groups in photoaffinity labelling. With this in mind, the chemistry of thirteen different classes of photoactivatable reagents that react through the formation of intermediate carbenes, electrophiles, dienes, or radicals, is assessed.


Assuntos
Preparações Farmacêuticas/química , Proteínas/química , Animais , Anticorpos/química , Linhagem Celular Tumoral , Radioisótopos de Cobre/química , Reação de Cicloadição , Humanos , Marcação por Isótopo , Ligantes , Metano/análogos & derivados , Metano/química , Camundongos , Camundongos Nus , Neoplasias/diagnóstico por imagem , Tomografia Computadorizada de Emissão de Fóton Único , Transplante Heterólogo , Raios Ultravioleta
16.
J Inorg Biochem ; 202: 110844, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31739113

RESUMO

Experimental organometallic gold(I) compounds hold promise for anticancer therapy. This study reports the synthesis of two novel families of gold(I) complexes, including N1-substituted bis-N-heterocyclic carbene (NHC) complexes of general formula [Au(N1-TBM)2]BF4 (N1-TBM = N1-substituted 9-methyltheobromin-8-ylidene) and mixed gold(I) NHC-alkynyl complexes, [Au(N1-TBM)alkynyl]. The compounds were fully characterised for their structure and stability in aqueous environment and in the presence of N-acetyl cysteine by nuclear magnetic resonance (NMR) spectroscopy. The structures of bis(1-ethyl-3,7,9-trimethylxanthin-8-ylidene)gold(I), (4-ethynylpyridine)(1,9-dimethyltheobromine-8-ylidene)gold(I) and of (2,8-Diethyl-10-(4-ethynylphenyl)-5,5-difluoro-1,3,7,9-tetramethyl-5H-4λ4,5λ4-dipyrrolo[1,2-c:2',1'-f][1,3,2]diazaborinine)(1,3,7,9-tetramethylxanthin-8-ylidene)gold(I) were also confirmed by X-ray diffraction analysis. The compounds were studied for their properties as DNA G-quadruplex (G4 s) stabilizers by fluorescence resonance energy transfer (FRET) DNA melting. Only the cationic [Au(N1-TBM)2]BF4 family showed moderate G4 stabilization properties with respect to the previously reported benchmark compound [Au(9-methylcaffein-8-ylidene)2]+ (AuTMX2). However, the compounds also showed marked selectivity for binding to G4 structures with respect to duplex DNA in competition experiments. For selected complexes, the interactions with G4 s were also confirmed by circular dichroism (CD) studies. Furthermore, the gold(I) complexes were assessed for their antiproliferative effects in human cancer cells in vitro, displaying moderate activity. Of note, among the mixed gold(I) NHC-alkynyl compounds, one features a fluorescent boron-dipyrromethene (BODIPY) moiety which allowed determining its uptake into the cytoplasm of cancer cells by fluorescence microscopy.


Assuntos
Antineoplásicos , Quadruplex G , Neoplasias , Compostos Organoáuricos , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Ligantes , Células MCF-7 , Metano/análogos & derivados , Metano/química , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Neoplasias/patologia , Compostos Organoáuricos/síntese química , Compostos Organoáuricos/química , Compostos Organoáuricos/farmacologia
17.
Molecules ; 24(23)2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31783706

RESUMO

The bis-glyoxylamide peptidomimetics have been synthesized from bis-N-acetylisatins linked at C5 by ring-opening with alcohols, amines, and amino acid methyl ester hydrochlorides. X-ray images of single crystals of bis-glyoxylamide peptidomimetics have been obtained.


Assuntos
Indóis/síntese química , Peptidomiméticos/síntese química , Álcoois/química , Aminas/química , Aminoácidos/química , Ésteres/química , Indóis/química , Isatina/química , Metano/análogos & derivados , Metano/química , Modelos Moleculares , Estrutura Molecular , Oxigênio/química , Peptidomiméticos/química , Raios X
18.
Top Curr Chem (Cham) ; 377(6): 37, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31728771

RESUMO

Over the past decade, the combination of visible light photocatalysis and organocatalysis has made remarkable progress in modern chemical synthesis. In these dual catalysis system, photocatalysts or photosensitizers absorb visible light to induce their photoexcited states which can activate unreactive substrates via electron or energy transfer mechanisms, and organocatalysts are usually employed to regulate the chemical reactivity of the other substrates. By doing so, two reactive species react with each in a selective-especially enantioselective-way, to provide the final products. This article summarizes the recent development of cooperative catalysis by the combination of organocatalysis and photocatalysis in asymmetric organic synthesis. These reactions are classified according to the manner of activation of the organocatalysts. Enamine/iminium catalysts are used to activate unreactive carbonyl molecules. Nucleophilic catalysts including nitrogen heterocycle carbene catalysts and tertiary amine catalysts are employed to reverse the reactivity of electrodeficient substrates including aldehydes and enals. Chiral Brønsted acid catalysts are used to activate substrates by forming key H-bonding complexes between substrates and catalysts.


Assuntos
Aminas/química , Iminas/química , Luz , Aldeídos/química , Alcenos/química , Catálise , Metano/análogos & derivados , Metano/química , Estereoisomerismo
19.
20.
Top Curr Chem (Cham) ; 377(6): 35, 2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31720874

RESUMO

N-Heterocyclic carbene (NHC) catalysis can access umpolung reactivity of carbonyl compounds as acyl anions, enolates and homoenolates. Considerable progress has been made in asymmetric transformation by the introduction of chirality to the NHC scaffold. However, the single catalyst system has limitations in chemo-, regio- and stereoselectivity. A solution to these problems has recently emerged with the synergistic combination of NHC catalysis and metal catalysis. A number of NHC/metal combinations have been found not only to improve reactivity and stereoselectivity, but also to enable access to unprecedented transformations. This paper highlights examples of successful asymmetric NHC/metal cooperative catalysis.


Assuntos
Metais/química , Metano/análogos & derivados , Catálise , Complexos de Coordenação/química , Compostos Heterocíclicos/química , Ácidos de Lewis/química , Metano/química , Estereoisomerismo
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