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1.
Org Lett ; 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38619225

RESUMO

As a class of rising electrophilic coupling reagents, aryl-thianthreniums (aryl-TTs) have been gaining immense attention. Herein, a novel palladium-catalyzed domino annulation of aryl-TTs with anhydrides is proposed to rapidly assemble a collection of highly functionalized fluorenones. This finding presents an innovative reaction pattern of aryl-TTs wherein the domino annulation version is first involved. Heavily compared with the existing conversions with aryl-TTs, this identified process successively functions as four aryl C-H bonds.

2.
Chem Commun (Camb) ; 60(26): 3571-3574, 2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-38469678

RESUMO

Herein, a novel Pd-catalyzed denitrogenation/vinylation of benzotriazinones using vinylene carbonate as the vinylation reagent is reported. This transformation demonstrates an unprecedented skeletal editing approach, effectively converting NN to CC fragments in situ and synthesizing a collection of isoquinolinones with broad-spectrum functional group tolerance. Moreover, the quite concise reaction system and late-stage modification of bioactive molecules comprehensively underscore the practical potential of this protocol.

3.
Dalton Trans ; 53(9): 4260-4265, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38344761

RESUMO

Sterically-hindered N-heterocyclic carbenes (NHCs) with functionalized N-wingtips are a pivotal class of ligands in organic synthesis. Herein, we report the first class of sterically-hindered N-heterocyclic carbenes based on the indazole framework. These ligands combine the strong σ-donation of the carbene center due to the carbene placement at the C3-indazole position with the sterically-hindered and flexible N-substitution with the versatile 2,6-bis(diphenylmethyl)aryl moiety that extends beyond the metal centre for the first time in non-classical N-heterocyclic carbenes. The ligands are readily accessible by the rare Cadogan indazole synthesis of sterically-hindered N-aryl-1-(2-nitrophenyl)methanimines. Steric and electronic characterization as well as catalytic studies in the synthesis of oxazolines are described. Considering the unique properties of indazole-derived carbenes, we anticipate that this class of compounds will find broad application in organic synthesis and catalysis.

4.
Molecules ; 29(4)2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38398616

RESUMO

Phytopathogenic fungi cause plant diseases and economic losses in agriculture. To efficiently control plant pathogen infections, a total of 19 spirotryprostatin A derivatives and 26 spirooxindole derivatives were designed, synthesized, and tested for their antifungal activity against ten plant pathogens. Additionally, the intermediates of spirooxindole derivatives were investigated, including proposing a mechanism for diastereoselectivity and performing amplification experiments. The bioassay results demonstrated that spirotryprostatin A derivatives possess good and broad-spectrum antifungal activities. Compound 4d exhibited excellent antifungal activity in vitro, equal to or higher than the positive control ketoconazole, against Helminthosporium maydis, Trichothecium roseum, Botrytis cinerea, Colletotrichum gloeosporioides, Fusarium graminearum, Alternaria brassicae, Alternaria alternate, and Fusarium solan (MICs: 8-32 µg/mL). Compound 4k also displayed remarkable antifungal activity against eight other phytopathogenic fungi, including Fusarium oxysporium f. sp. niveum and Mycosphaerella melonis (MICs: 8-32 µg/mL). The preliminary structure-activity relationships (SARs) were further discussed. Moreover, molecular docking studies revealed that spirotryprostatin A derivatives anchored in the binding site of succinate dehydrogenase (SDH). Therefore, these compounds showed potential as natural compound-based chiral fungicides and hold promise as candidates for further enhancements in terms of structure and properties.


Assuntos
Antifúngicos , Benzopiranos , Fungicidas Industriais , Nitrilas , Oxindóis , Piperazinas , Compostos de Espiro , Antifúngicos/química , Simulação de Acoplamento Molecular , Relação Estrutura-Atividade , Fungicidas Industriais/farmacologia
5.
Org Lett ; 25(33): 6149-6154, 2023 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-37578346

RESUMO

Herein, we report an exceedingly mild method for the direct, transition-metal-free esterification of thioamides through the selective generation of tetrahedral intermediates. The method represents the first transition-metal-free approach to the thioamide to thionoester transformation in organic synthesis. This reactivity has been accomplished through N,N-Boc2-thioamides that engage in ground-state destabilization of the nN → π*C═S conjugation. The ground-state destabilization of "single-atom" bioisosteric thioamides will expand the arsenal of valuable amide bond functionalization reactions.

6.
Chem Sci ; 14(19): 5160-5166, 2023 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-37206409

RESUMO

Herein, we disclose a novel reorganization/cycloaddition between two imine units catalyzed by In(OTf)3 Lewis acid that differs from the well-known [4 + 2] cycloaddition version via the Povarov reaction. By means of this unprecedented imine chemistry, a collection of synthetically useful dihydroacridines has been synthesized. Notably, the obtained products give rise to a series of structurally novel and fine-tuneable acridinium photocatalysts, offering a heuristic paradigm for synthesis and efficiently facilitating several encouraging dihydrogen coupling reactions.

7.
Chem Commun (Camb) ; 59(37): 5599-5602, 2023 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-37078598

RESUMO

The synergistic modulation of fluorescence resonance energy transfer (FRET) and the inner filter effect (IFE) was constructed within a molecule to control the stable fluorescence intensity as the internal standard, providing a new strategy for the accurate monitoring of photoactivation.

8.
Chem Sci ; 14(12): 3338-3345, 2023 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-36970078

RESUMO

Direct functionalization of the C(O)-N amide bond is one of the most high-profile research directions in the last few decades; however oxidative couplings involving amide bonds and functionalization of thioamide C(S)-N analogues remain an unsolved challenge. Herein, a novel hypervalent iodine-induced twofold oxidative coupling of amines with amides and thioamides has been established. The protocol accomplishes divergent C(O)-N and C(S)-N disconnection by the previously unknown Ar-O and Ar-S oxidative coupling and highly chemoselectively assembles the versatile yet synthetically challenging oxazoles and thiazoles. Employing amides instead of thioamides affords an alternative bond cleavage pattern, which is a result of the higher conjugation in thioamides. Mechanistic investigations indicate ureas and thioureas generated in the first oxidation as pivotal intermediates to realize the oxidative coupling. These findings open up new avenues for exploring oxidative amide and thioamide bond chemistry in various synthetic contexts.

9.
Dalton Trans ; 52(2): 434-443, 2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36524392

RESUMO

In this article, a novel triphenylamine-modified salicylaldehyde Schiff base 2-(((4-(diphenylamino)phenyl)imino)methyl)-4-(pyridine-4-yl)phenol (HL) was synthesized and structurally characterized. HL possessed D-π-A structure and exhibited typical AIE property in THF/H2O. It was applied to selectively recognize Cu2+ through an on-off mode in THF/H2O (1/9, v/v), and the fluorescence attenuation was attributed to a paramagnetic quenching effect of Cu2+ together with the abatement of HL aggregates. Hence, the detection limit achieved was as low as 1.32 × 10-7 M. The spectroscopic and ESI-HRMS results revealed a 1 : 2 complexation ratio of Cu2+ with HL. The mechanism for sensing Cu2+ was further confirmed by performing DFT calculations. Owing to the large affinity between Cu2+ and His, the resultant CuL2 system was further used to detect His via the off-on method based on the displacement of ligands. The detection limit for His reached 5.14 × 10-8 M. Furthermore, HL was available to prepare handy indicator papers for the on-site recognition of Cu2+ and His. Confocal fluorescent imaging demonstrated that HL could sequentially respond to intracellular Cu2+ and His.


Assuntos
Cobre , Bases de Schiff , Bases de Schiff/química , Espectrometria de Fluorescência , Cobre/química
10.
Molecules ; 27(15)2022 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-35956890

RESUMO

Inappropriate and disproportionate antibiotic use contributes immensely to the development of antibiotic resistance in bacterial species associated with food contamination. Therefore, alternative strategies to treat multidrug-resistant (MDR) bacterial infections are urgently needed. In this study, verbascoside was shown to exhibit excellent antibacterial activity and synergistic effects in combination with cell wall synthesis-inhibiting antibiotics, indicating that it can be used as an adjuvant to restore or increase the activity of antibiotics against resistant pathogens. In a mechanistic study, higher concentrations of verbascoside resulted in a longer lag phase and a lower specific exponential-phase growth rate of bacteria. Furthermore, verbascoside exerted its antimicrobial activity through multiple mechanisms, including cell membrane dysfunction, biofilm eradication and changes in cell morphology. The promising antibacterial activity and in vitro safety assessment results suggested that verbascoside can be used as a food additive for fresh meat preservation. Treatment with medium and high doses of verbascoside caused significant bacterial death in meat samples, slowed the spoilage rate, and extended the shelf life. Collectively, verbascoside is expected to be useful as an antibiotic adjuvant to prevent or treat resistant bacteria-related infections and an alternative novel antimicrobial additive in the food industry.


Assuntos
Antibacterianos , Carne , Antibacterianos/farmacologia , Bactérias , Farmacorresistência Bacteriana Múltipla , Glucosídeos , Carne/microbiologia , Testes de Sensibilidade Microbiana , Fenóis
11.
ACS Omega ; 7(21): 18017-18026, 2022 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-35664592

RESUMO

A D-π-A type quinoline derivative, 2-(((4-(1, 2, 2-triphenylvinyl)phenyl)imino)methyl)quinolin-8-ol (HL), was synthesized and structurally characterized. The five-membered ring formed by the O-H···N hydrogen bond in HL contributed to the excited-state intramolecular proton transfer (ESIPT) behavior of HL, which was further verified by theoretical computations. Upon coordination with Zn2+, the hydroxyl proton in HL was removed, resulting in the inhibition of ESIPT. In the meanwhile, the formed Zn 2 L 4 complex displayed aggregation-induced emission (AIE) character in THF/H2O mixtures, which is conducive to the fluorescence enhancement in aqueous media. Structure analysis suggested that the origin of the AIE characteristic was attributed to restriction of intramolecular rotations along with the formation of J-aggregates. Based on ESIPT coupled with AIE, HL could recognize Zn(II) in aqueous media via an orange fluorescence turn-on mode. Benefitting from the AIE property, chemosensor HL was successfully applied to fabricate test strips for rapid sensing of Zn(II) ions.

12.
Chem Commun (Camb) ; 58(53): 7404-7407, 2022 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-35694980

RESUMO

We report the synthesis, characterization and reactivity of an air-stable, well-defined acenaphthoimidazolylidene palladium-BIAN-NHC chloro dimer complex, [Pd(BIAN-IPr)(µ-Cl)Cl]2. This rapidly activating catalyst merges the reactive properties of palladium chloro dimers, [Pd(NHC)(µ-Cl)Cl]2, with the attractive structural features of the BIAN framework. [Pd(BIAN-IPr)(µ-Cl)Cl]2 is the most reactive Pd(II)-NHC precatalyst discovered to date undergoing fast activation under both an inert atmosphere and aerobic conditions. The catalyst features bulky-yet-flexible sterics that render the C-H substituents closer to the metal center in combination with rapid dissociation to monomers and strong σ-donor properties. [Pd(BIAN-IPr)(µ-Cl)Cl]2 should be considered as a catalyst for reactions using well-defined Pd(II)-NHCs.

13.
Org Biomol Chem ; 20(30): 5981-5988, 2022 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-35441645

RESUMO

Thioamides are 'single-atom' isosteres of amide bonds that have found broad applications in organic synthesis, biochemistry and drug discovery. In this New Talent themed issue, we present a general strategy for activation of N-C(S) thioamide bonds by ground-state-destabilization. This concept is outlined in the context of a full study on transamidation of thioamides with nucleophilic amines, and relies on (1) site-selective N-activation of the thioamide bond to decrease resonance and (2) highly chemoselective nucleophilic acyl addition to the thioamide CS bond. The follow-up collapse of the tetrahedral intermediate is favored by the electronic properties of the amine leaving group. The ground-state-destabilization concept of thioamides enables weakening of the N-C(S) bond and rationally modifies the properties of valuable thioamide isosteres for the development of new methods in organic synthesis. We fully expect that in analogy to the burgeoning field of destabilized amides introduced by our group in 2015, the thioamide bond ground-state-destabilization activation concept will find broad applications in various facets of chemical science, including metal-free, metal-catalyzed and metal-promoted reaction pathways.


Assuntos
Aminas , Tioamidas , Amidas/química , Tioamidas/química
14.
Org Lett ; 24(12): 2338-2343, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35297638

RESUMO

The direct synthesis of ketones via acyl Suzuki-Miyaura cross-coupling of widely available acyl chlorides is a central transformation in organic synthesis. Herein, we report the first mechanochemical solvent-free method for highly chemoselective synthesis of ketones from acyl chlorides and boronic acids. This acylation reaction is conducted in the solid state, in the absence of potentially harmful solvents, for a short reaction time and shows excellent selectivity for C(acyl)-Cl bond cleavage.

15.
J Ethnopharmacol ; 289: 115060, 2022 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-35121049

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Urtica fissa E. Pritz. are important herbs and have been traditionally used as ethnic medicine to treat rheumatism, inflammation, diabetes, and benign prostatic hyperplasia by the Han, Uighur, and other minorities in China, and also as an aphrodisiac in Uighur medicine. AIMS OF THE STUDY: To determine the effect and potential mechanism of 3, 4-divanillyltetrahydrofuran (DVTF), one of the main active components isolated from U. fissa on hypogonadism in diabetic mice. MATERIALS AND METHODS: The active compound DVTF was extracted and separated from the roots of U. fissa and identified using mass spectrometry and nuclear magnetic resonance spectroscopy. A mouse model of diabetes was established using high fat and sugar diet combined with streptozotocin. In the treatment groups, mice were received different doses of DVTF for 4 weeks. Fasting blood glucose levels, physiological and biochemical indices, and the mating behavior of DM mice were analyzed. Changes in testicular morphology were assessed using light microscopy and transmission electron microscopy. The expression of testosterone synthesis-related signaling proteins was detected using western blotting. Molecular docking was used to determine the binding ability of DVTF to Nur77. RESULTS: In diabetic mice, body weight and fasting blood glucose levels decreased. Mating behavior, including mount latency, mount number, and intromission number, was improved following DVTF treatment. Plasma total testosterone, free testosterone, and insulin resistance were positively associated with the recovery of testicular pathological structures in diabetic mice. DVTF treatment increased the expression of Nur77, StAR, and P450scc in the testes of diabetic mice. DVTF and Nur77 formed chemical bonds at five sites. CONCLUSION: As one of the main active components of U. fissa, DVTF exert potential therapeutic effects on testicular injury and hypogonadism caused by diabetes through activating the expression of Nur77 and testosterone synthesis related proteins. Our result will provide new insight for the clinical application of Urtica fissa E. Pritz., especially DVTF, as a potential drug candidate in the treatment of hypogonadism in diabetes.


Assuntos
Diabetes Mellitus Experimental/tratamento farmacológico , Furanos/farmacologia , Hipogonadismo/tratamento farmacológico , Lignina/farmacologia , Urticaceae/química , Animais , Diabetes Mellitus Experimental/complicações , Feminino , Furanos/isolamento & purificação , Regulação da Expressão Gênica/efeitos dos fármacos , Hipogonadismo/etiologia , Resistência à Insulina , Lignina/isolamento & purificação , Masculino , Camundongos , Camundongos Endogâmicos ICR , Simulação de Acoplamento Molecular , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/genética , Comportamento Sexual Animal/efeitos dos fármacos , Disfunções Sexuais Fisiológicas/tratamento farmacológico , Disfunções Sexuais Fisiológicas/etiologia , Estreptozocina , Testículo/efeitos dos fármacos , Testosterona/sangue
16.
Commun Chem ; 5(1): 60, 2022 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-36697942

RESUMO

Over the last 20 years, N-heterocyclic carbenes (NHCs) have emerged as a dominant direction in ligand development in transition metal catalysis. In particular, strong σ-donation in combination with tunable steric environment make NHCs to be among the most common ligands used for C-C and C-heteroatom bond formation. Herein, we report the study on steric and electronic properties of thiazol-2-ylidenes. We demonstrate that the thiazole heterocycle and enhanced π-electrophilicity result in a class of highly active carbene ligands for electrophilic cyclization reactions to form valuable oxazoline heterocycles. The evaluation of steric, electron-donating and π-accepting properties as well as structural characterization and coordination chemistry is presented. This mode of catalysis can be applied to late-stage drug functionalization to furnish attractive building blocks for medicinal chemistry. Considering the key role of N-heterocyclic ligands, we anticipate that N-aryl thiazol-2-ylidenes will be of broad interest as ligands in modern chemical synthesis.

17.
Angew Chem Int Ed Engl ; 61(7): e202114146, 2022 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-34877756

RESUMO

Although cross-coupling reactions of amides by selective N-C cleavage are one of the most powerful and burgeoning areas in organic synthesis due to the ubiquity of amide bonds, the development of mechanochemical, solid-state methods remains a major challenge. Herein, we report the first mechanochemical strategy for highly chemoselective, solvent-free palladium-catalyzed cross-coupling of amides by N-C bond activation. The method is conducted in the absence of external heating, for short reaction time and shows excellent chemoselectivity for σ N-C bond activation. The reaction shows excellent functional group tolerance and can be applied to late-stage functionalization of complex APIs and sequential orthogonal cross-couplings exploiting double solventless solid-state methods. The results extend mechanochemical reaction environments to advance the chemical repertoire of N-C bond interconversions to solid-state environmentally friendly mechanochemical methods.

18.
Org Lett ; 23(22): 8910-8915, 2021 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-34757750

RESUMO

Chemical transformation with vinylene carbonate as an emerging synthetic unit has recently attracted considerable attention. This report is a novel conversion pattern with vinylene carbonate, in which such a vibrant reagent unprecedentedly acts as a difunctional coupling partner to complete the C-H annulation of free anilines. From commercially available substrates, this protocol leads to the rapid construction of synthetically versatile 2-methylquinoline derivatives (43 examples) with excellent functionality tolerance.

19.
Org Lett ; 23(21): 8527-8532, 2021 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-34670369

RESUMO

Here we report a novel Rh-catalyzed C-H/C-H alkenylation of N-arylmethanimines with vinylene carbonate acting as a vinylene unit. Forty examples of C3,C4-nonsubstituted quinolines were achieved from commercially available starting materials. This identified process features an exceedingly simple system, a lower loading of catalyst, and the capacity for postfunctionalization with bioactive molecules.

20.
Chem Commun (Camb) ; 57(40): 4930-4933, 2021 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-33870963

RESUMO

A zinc-catalyzed C-H alkenylation of quinoline N-oxides with ynones has been developed to rapidly assemble a broad collection of valuable quinoline-enol organic architectures. Uncommonly, this novel reaction involves C-H functionalization, and N-O, C-C and C[triple bond, length as m-dash]C bond cleavage in one operation, and leads exclusively to the formation of an enol rather than a keto product. Application of the enols generated was highlighted by further derivative transformation and preparation of a series of "BODIPY" analogues with high quantum yields (up to 86%).

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