RESUMEN
In this study, a novel fluorescent probe, MAC-2, for the detection of Au3+ was designed and synthesised using cellulose as a carrier combined with benzothiazole derivatives. The structure of the probe was confirmed by SEM, XRD, FTIR, and 1H NMR, also the optical properties of the product were investigated. MAC-2 showed bright green fluorescence under a 365 nm UV lamp and exhibited significant quenching behaviour toward Au3+. MAC-2 utilises more sustainable biomass resources, featuring green and biodegradable characteristics that meet environmental requirements. Compared with most reported probes, it exhibits notable fluorescence properties. The limit of detection (LOD) is as low as 0.057 µM, and the response time is 1 min. It also demonstrates good specific recognition and anti-interference abilities. In addition, a smartphone was used as a portable signal processing device to achieve rapid detection of Au3+ concentration. Meanwhile, MAC-2 was successfully prepared as a fluorescent test strip, providing a potential application for the convenient detection of Au3+. The high sensitivity and selectivity exhibited by cellulose-based fluorescent probes in detecting Au3+ offer valuable insights and new ideas for the detection of other metal ions and biomolecules. These inspirations will help promote the continuous development of research and applications in related fields.
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Celulosa , Colorantes Fluorescentes , Oro , Teléfono Inteligente , Celulosa/química , Celulosa/análogos & derivados , Colorantes Fluorescentes/química , Oro/química , Espectrometría de Fluorescencia/métodos , Límite de DetecciónRESUMEN
We have disclosed a Rauhut-Currier reaction of γ-alkyl-substituted allenoate, catalyzed by L-valine-derived amide phosphine, to form trisubstitued allenoate, which was trapped by maleimide or DMAD via the Diels-Alder reaction. Exo-bicyclic succinimide derivatives including three continuous stereocenters with an exo-carbon-carbon double bound were constructed in up to quantitative yields with high stereospecificity.
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The unprecedented dimerizations of 2H-azirines have been developed under the catalysis of palladium and silver. Upon changing the reaction conditions, the fully aryl-substituted pyrrole and pyrimidine derivatives were furnished in moderate yields with regiospecificity, respectively. Control experiments uncovered distinct catalytic effects of two transition metals, and the proposed catalytic cycles plausibly rationalized the chemodivergence and regioselectivity.
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An efficient method for the construction of various 3,4,5-trisubstituted phenol derivatives has been achieved via the Rh(III)-catalyzed coupling of phosphonium cations with internal alkynes. This protocol shows good substrate compatibility, as an array of structurally and electronically diverse phosphonium compounds react efficiently with up to 87% yield.
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The metal-free cyclization of allenyl ketones and p-toluenesulfonylmethyl isocyanide (TosMIC), promoted by Cs2CO3, provides a convenient access to tetrasubstituted pyrroles in which an acyl group undergoes 1,2-migration. This tandem Michael addition/annulative migration synthetic strategy is general and high-yielding for various substituted allenyl ketones. Moreover, a phosphoryl or ester moiety is also a suitable functionality to enable such migration.
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In this article, a practical and metal-free method for the synthesis of poly-functionalized 3-selenyl/sulfenyl/telluriumindoles from o-alkynyl arylamines has been achieved. In this protocol, the in situ formation of selenenyl chloride, sulfenyl chloride or tellurenyl chloride is considered as the key intermediate and the 3-selenyl/sulfenyl/telluriumindoles can be obtained in good to excellent yields. Furthermore, the product 2-phenyl-3-(phenylselanyl)-1-tosyl-1H-indole can be selectively oxidized to compounds 2-phenyl-3-(phenylseleninyl)-1-tosyl-1H-indole and 2-phenyl-3-(phenylselenonyl)-1-tosyl-1H-indole in good yields.
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A rhodium-catalyzed formal [4 + 1]-cyclization reaction of aryl substituted pyrazoles with cyclopropanols via C-H bond activation/cyclization processes to selectively construct a series of carbonyl functionalized pyrazolo[5,1-a]isoindoles is described. The reaction features good functional group compatibility and a broad substrate scope with respect to both cyclization components with up to 84% yields. Mechanistic studies indicated that the C-H cleavage might be the rate-determining step in this transformation.
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An effective rhodium(III) catalysis for the construction of valuable tetracyclic compounds is described herein. This domino process involving the C-H activation/[3 + 2] annulation/intramolecular Friedel-Crafts reaction sequences of simple and readily available N-Boc hydrazones and propargylic monofluoroalkynes afforded fused tetracyclic spiro[cyclobutane-1,9'-indeno[1,2-a]indenes] in moderate to good yields, featuring three C-C bond formation. Moreover, control experiments indicated that the C-H activation might be involved in the rate-determining step.
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Ciclobutanos , Indenos , Rodio , Catálisis , Ciclización , Hidrazonas/química , Indenos/química , Estructura Molecular , Rodio/químicaRESUMEN
The in situ formed furan-fused cyclobutenes via Cu(I)-catalyzed cycloisomerization of readily available allenyl ketones bearing a cyclopropyl moiety are a highly reactive and powerful species, which undergo annulative fragmentation with terminal ynones to afford a wide variety of functional furans in moderate to high yields. This ring-distortion protocol features an unprecedented strain-controlled cycloisomerization/Diels-Alder/retro-Diels-Alder (CDRD) sequence under mild conditions.
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Through a facile post-synthetic method, different kinds of polar group-functionalized ionic liquid porous organic polymers (POP-PA-COOH, POP-PA-OH, and POP-PA-NH2) were obtained. The materials can be used as efficient heterogeneous catalysts in the cycloaddition reaction of CO2 with epoxides under mild and co-catalyst-free conditions. It is demonstrated that POP-PA-NH2 possesses much higher catalytic activity than POP-PA-OH and POP-PA-COOH. Interestingly, this activity difference can further be amplified when the reaction is carried out under low CO2 concentration, and POP-PA-NH2 possesses a conversion of 84.7% with a selectivity of 99.0% in 96 h. It is noteworthy to mention that research focusing on the transformation of CO2 under low concentration using heterogeneous catalysts is rare and still a challenge. The excellent activities of POP-PA-NH2 under low CO2 concentration make this material a good candidate for CO2 elimination under mild conditions.
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We disclose an l-isoleucine-derived amide phosphine-catalyzed trimerization of γ-aryl-3-butynoates, which undergo an isomerization to allenoate, [3 + 2] cyclization, and Michael addition cascade. Exocyclopentene derivatives bearing an all-carbon quaternary stereocenter were constructed stereospecifically and enantioselectively. A wide variety of γ-aryl-3-butynoates could be employed to deliver optically pure cyclopentene derivatives in moderate to good yields with ee values of ≥95% and in most cases ≥98%.
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Chinese sturgeon (Acipenser sinensis) is a critically endangered species, and waters downstream from Gezhouba Dam are the only known spawning ground. To optimize the velocity conditions in the spawning ground by controlling the opening mode of Gezhouba Dam generator units, a mathematical model of Chinese sturgeon spawning ground was established in FLOW-3D. The model was evaluated with velocity measurements, and the results were determined to be in good agreement. By inverting the 2016-2019 field monitoring results, the model shows that the preferred velocity range for Chinese sturgeon spawning is 0.6-1.5 m/s. Velocity fields of different opening modes of the generator units were simulated with identical discharge. The suitable-velocity area was maximal when all units of Dajiang Plant of Gezhouba Dam were open. For discharges below 12,000 m3/s, most of the area was suitable; for discharges above 12,000 m3/s, the suitable area rapidly decreased with increasing discharge. A comparison of suitable areas under high-flow showed that at discharges of 12,000-15,000 m3/s, opening 11-13 units on the left side was optimal. For discharges above 15,000 m3/s, all units should be open. We used these results to recommend a new operation scheme to support the conservation of Chinese sturgeon.
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Peces , Animales , Líquidos Corporales , China , Especies en Peligro de ExtinciónRESUMEN
The inherently strained furan-fused cyclobutenes, in situ generated via cycloisomerizations of allenyl ketones bearing cyclopropyl moiety under gold catalysis, have been utilized as reactive building blocks toward cross cycloadditions. The [4 + 2] and [3 + 2] annulations of these species with benzo[c]isoxazoles and N-iminoquinazolinium ylides furnish various three-dimensional cyclobutane-bridged polyheterocycles in good yields. A wide range of typically electron-deficient 1,3-dienes, heterodienes, and 1,3-dipoles can trap furan-fused cyclobutenes to afford several polycyclic architectures.
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A Ru(ii)-catalyzed coupling of various α-carbonyl phosphoniums with sulfoxonium ylides has been realized for the facile synthesis of 1-naphthols in good to excellent yields. This oxidant-free transformation proceeds through Ru-catalyzed C-H activation of phosphoniums, Ru-carbene insertion, and intramolecular Wittig reaction processes.
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A palladium-catalyzed hydroalkylation reaction of methylenecyclopropanes via highly selective C-C σ-bond scission was achieved under mild conditions, in which simple hydrazones served as carbanion equivalents. This method featured good functional group compatibility, affording high yields of C-alkylated terminal alkenes.
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An electrocatalytic reductive amination of electron-deficient aldehydes/ketones was developed, which could be used in the synthesis of functionalized tertiary amines and large scale preparation of racemic clopidogrel. A plausible mechanism involving an iminium cation intermediate was proposed.
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Aldehídos/química , Clopidogrel/química , Electrólisis , Cetonas/química , Aminación , Transporte de Electrón , Tecnología Química Verde , EstereoisomerismoRESUMEN
A palladium and iodine-cocatalyzed 5-exo-dig aza-thiocyclization of 8-alkynylnaphthalen-1-amines for the synthesis of (E)-2-alkylene-1,2-dihydrobenzo[cd]indole thioethers is reported. As a result of broad reaction scope, simple operation, mild conditions, and high stereoselectivity and regioselectivity, this reaction should have potential utility in organic synthesis.
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Silver-catalyzed stereoselective synthesis of polysubstituted ( Z)-1,2-dihydrobenzo[ cd]indoles from 8-ethynylnaphthalen-1-amines is reported. In this protocol, a series of nitrogen-containing heterocyclic compounds were synthesized by silver-catalyzed α-addition of an alkyne bond with high selectivity and high yields. The synthesized polysubstituted 1,2-dihydrobenzo[ cd]indoles could be easily converted to benzo[ cd]indol-2(1 H)-ones, and both 1,2-dihydrobenzo[ cd]indoles and benzo[ cd]indol- 2(1 H)-ones are biological and pharmaceutical cores.
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A formal α-addition of N-propiolamide and 2-bromoacetate is reported for the synthesis of α-methylene-ß-lactam in good yields. The transformation proceeds smoothly in the presence of K2CO3 as a base and KI as an additive. An excellent reaction scope is observed. A 2 mmol scaled synthesis of α-methylene-ß-lactams and synthetic applications of α-methylene-ß-lactams are also reached. In the process, it is believed that an intramolecular 1,2-addition of N-propiolamide and sequential C-C bond migrating cleavage are involved.
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beta-Lactamas/química , Aziridinas , Estructura MolecularRESUMEN
In this paper, a metal-free protocol of nucleophilic ortho-halogenation and hydroxylation of anilines via an aromatic Pummerer process is reported.