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1.
Org Lett ; 26(17): 3661-3666, 2024 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-38656155

RESUMO

Considering the ubiquitous presence of pyridine moieties in pharmaceutical compounds, it holds immense value to develop practical and straightforward methodologies for accessing heterocyclic aromatic hydrocarbons. In recent years, N-alkoxypyridinium salts have emerged as convenient radical precursors, enabling the generation of the corresponding alkoxy radicals and pyridine through single-electron transfer. Herein, we present the first report on visible-light-mediated intermolecular alkoxypyridylation of alkenes employing N-alkoxylpyridinium salts as bifunctional reagents with an exceptionally low catalyst loading (0.5 mol %).

2.
Org Lett ; 26(1): 315-320, 2024 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-38175121

RESUMO

A protocol was developed to achieve stereodivergent synthesis of stereoisomers of δ-lactam bearing vicinal chiral centers. Organocatalytic cascade reactions were employed to produce the target products as the kinetic products, which exhibited remarkable enantioselectivities. In the presence of DBU, the kinetic product underwent epimerization to form a thermodynamically more stable diastereomer without loss in enantioselectivity. By simply switching the chiral organocatalyst and its enantiomer, we can efficiently obtain four stereoisomers with high enantioselectivities.

3.
Chem Commun (Camb) ; 59(14): 2003-2006, 2023 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-36723060

RESUMO

A mild metal-free C-N bond activation strategy for the direct conversion of inert tertiary amines with acyl chlorides into tertiary amides via organic photoredox catalysis is presented. In this protocol, a novel organic photocatalyst (Cz-NI-Ph) that showed excellent catalytic performance during C-N bond cleavage is developed. Moreover, this reaction features green and mild conditions, broad substrate scope, and readily available raw materials.

4.
BMC Genomics ; 24(1): 81, 2023 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-36810020

RESUMO

Trichosanthes kirilowii Maxim. (TK) is a dioecious plant in the Cucurbitaceae family of which different sexes have separate medicinal uses. We used Illumina high-throughput sequencing technology to sequence miRNAs from male and female flower buds of TK. We performed bioinformatics analysis, miRNA identification, and target gene prediction on the data obtained from sequencing, and association analysis was performed in combination with the results of a previous transcriptome sequencing study. As a result, there were 80 differentially expressed miRNAs (DESs) between the female and male plants (48 upregulated and 32 downregulated in female plants). Moreover, 27 novel miRNAs in DESs were predicted to have 282 target genes, and 51 known miRNAs were predicted to have 3418 target genes. By establishing a regulatory network between miRNAs and target genes, 12 core genes were screened, including 7 miRNAs and 5 target genes. Among them, tkmiR157a-5p, tkmiR156c, tkmiR156_2, and tkmiR156k_2 jointly target the regulation of tkSPL18 and tkSPL13B. These two target genes are specifically expressed in male and female plants, respectively, and are involved in the biosynthesis process of BR, which is closely related to the sex differentiation process of TK. The identification of these miRNAs will provide a reference for the analysis of the sex differentiation mechanism of TK.


Assuntos
Cucurbitaceae , MicroRNAs , Trichosanthes , Trichosanthes/genética , MicroRNAs/genética , Regulação da Expressão Gênica de Plantas , Cucurbitaceae/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos
5.
J Org Chem ; 87(2): 1493-1501, 2022 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-35014249

RESUMO

Herein, we report an efficient photoinduced radical tandem trifluoromethylation/cyclization reaction of N-cyanamide alkenes for the synthesis of functionalized quinazolinones. Importantly, the reaction is carried out under mild conditions without any additional photosensitizer, metal, or extra additives. A series of trifluoromethyl quinazolinones were prepared efficiently with good yields and excellent functional group tolerance. Preliminary mechanistic experiments were conducted to indicate that the transformation proceeds via a possible mechanism involving photoexcited EDA complex and chain propagation.


Assuntos
Fármacos Fotossensibilizantes , Quinazolinonas , Catálise , Ciclização , Luz
6.
J Org Chem ; 86(23): 17156-17163, 2021 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-34794309

RESUMO

A visible-light-driven multistep tandem reaction between vinyl azides and alkyl bromides has been developed leading to the formation of tetralone skeletons under mild conditions, which can be easily scaled up to the gram scale. Various 1-tetralone derivatives are synthesized and transformed into desired products in good to high yields.

7.
Org Lett ; 23(13): 5033-5038, 2021 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-34138570

RESUMO

A novel approach for the asymmetric construction of polycyclic indazole skeletons via enamine-imine activation and PCET activation was developed by merging organocatalysis with photocatalysis through an asymmetric triple-reaction sequence. In this process, five C-X bonds and five consecutive chiral centers were efficiently constructed. Differently substituted polycyclic indazole deriatives were successfully constructed with satisfactory results under mild conditions.

8.
Org Lett ; 23(9): 3287-3293, 2021 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-33861618

RESUMO

A novel one-pot triple-reaction strategy for the asymmetric construction of polycyclic skeletons with multiple consecutive chiral centers through aza-Michael/Michael/Wittig/ketyl radical addition/esterification processes is reported. A wide range of polycyclic tetrahydroquinoline derivatives were smoothly obtained from easily available starting materials with good results (up to 80% yield, >20:1 dr, >99% ee) under mild conditions. In this transformation, five chemical bonds and five consecutive chiral centers were successively formed.

9.
Org Lett ; 22(3): 1028-1033, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31939306

RESUMO

A series of novel biselectrophilic ß,γ-unsaturated α-ketoesters were designed and synthesized from rhodanine. Under the catalysis of chiral squaramides, the enantioselective [3 + 3] annulation reaction of these novel ketoesters with pyrazolones was developed. This reaction offers an efficient method for the synthesis of chiral 2'-thioxo-5,6-dihydrospiro[pyrano[2,3-c]pyrazole-4,5'-thiazolidin]-4'-ones.

10.
J Org Chem ; 84(21): 13871-13880, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31553609

RESUMO

Herein, we describe a variety of chiral hybrid pyrroidine-indole polycyclic derivatives with quaternary and continuous chiral centers were synthesized in good yields with excellent stereoselectivities through an asymmetric, intermolecular, and formal [3 + 2] cyclization reaction catalyzed by a bifunctional catalyst. In addition, the selection of substituents of substrates is the key to success, and both the hydroxyl group and the trifluoromethyl group play essential roles in the reaction.

11.
Org Lett ; 20(18): 5835-5839, 2018 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-30203983

RESUMO

A dearomative remote activation strategy for the asymmetric functionalization of benzylic C-H bonds of heteroaryl aldehydes under bifunctional Brønsted base catalysis has been developed. The in situ generated o-QDMs-type dienolate intermediates were efficiently and stereoselectively trapped by nitroolefins through an asymmetric Michael/nitro-aldol cascade reaction. Using this strategy, a wide variety of synthetically significant tetrahydrodibenzothiophene and tetrahydrodibenzofuran derivatives were synthesized in good yields with high enantioselectivities.

12.
Mol Med Rep ; 18(3): 3137-3142, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30066945

RESUMO

The present study identified the cytotoxic effects of etomidate on the N2a neuroblastoma cell line. Etomidate induced apoptosis in N2a cells in a concentration­dependent manner, which was confirmed by western blotting and flow cytometry. Phase contrast microscopy was used to analyze the effect of etomidate on morphological characteristics. The number of the apoptotic cells was increased and confirmed by DAPI and PI staining, which served as a characteristic hallmark of apoptosis. Additionally, etomidate led to loss of mitochondrial membrane potential and resulted in the generation of reactive oxygen species in N2a cells. The western blot analysis revealed that N2a cells treated with etomidate had a significant modulation of pro­apoptotic proteins, includingpoly ADP­ribose polymerase (PARP), cleaved PARP, caspase­9 and procaspase­3. In conclusion, the present study determined that etomidate induced cytotoxic and apoptotic effects in N2a brain tumor cells in vitro.


Assuntos
Anestésicos/farmacologia , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Neoplasias Encefálicas/tratamento farmacológico , Etomidato/farmacologia , Neuroblastoma/tratamento farmacológico , Animais , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos , Neuroblastoma/metabolismo , Neuroblastoma/patologia , Espécies Reativas de Oxigênio/metabolismo
13.
Org Lett ; 20(15): 4471-4474, 2018 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-30019903

RESUMO

Direct visible-light-mediated aminofluorination of styrenes has been developed with high regioselectivity. Shelf-stable N-Ts-protected 1-aminopyridine salt was used as the nitrogen-radical precursor, and the commercially available hydrogen fluoride-pyridine was used as the nucleophilic fluoride source. The synthesis of an analogue of LY503430 was performed to demonstrate the synthetic value of this strategy.

14.
Org Lett ; 19(24): 6666-6669, 2017 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-29192791

RESUMO

A 3,4,5-trimethylphenol and Lewis acid dual-catalyzed cascade reaction of donor-acceptor (D-A) cyclopropanes via ring-opening and cyclization is developed. In this reaction, a phenolic compound was used as a covalent catalyst for the first time. Additionally, control experiments proved that 3,4,5-trimethylphenol completed the catalytic cycle by accomplishing the C-C bond cleavage. Using this strategy, a wide variety of substituted naphthalenes has been synthesized from D-A cyclopropanes in moderate to high yields under mild conditions.

15.
Org Lett ; 19(23): 6288-6291, 2017 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-29155594

RESUMO

A novel visible-light-induced aza-pinacol rearrangement was developed for the first time. In this approach, the addition of the N-centered radical to the C═C bond of alkylidenecyclopropanes delivers a variety of cyclobutanimines and γ-butyrolactones, with all-carbon quaternary centers via the ring expansion of the cyclopropyl group, in moderate to good yields under mild reaction conditions.

16.
J Org Chem ; 82(2): 1013-1023, 2017 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-27997799

RESUMO

On the basis of the Lewis acid-catalyzed Friedel-Crafts alkylation between 1-acyl-2-arylcyclopropanecarboxylate esters and electron-rich phenols, a Sc(OTf)3 catalyzed cascade [4 + 2]-annulation reaction was developed for the direct synthesis of polysubstituted dihydronaphthols from phenols. In this reaction, the structure of products is dominated by the directing effect of the substituent groups on phenols. Meanwhile, a one-pot Friedel-Crafts alkylation/oxidative cyclization reaction was also developed for the synthesis of spiro-fused 2,5-cyclohexadienones.

17.
J Org Chem ; 81(21): 10532-10537, 2016 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-27649297

RESUMO

A highly regioselective DBU-catalyzed [3 + 2] annulation of Morita-Baylis-Hillman carbonates with isothiocyanates was developed. This method allows rapid and efficient synthesis of spirocyclic oxindole dihydrothiophene products in moderate to high yields with excellent regioselectivities under simple conditions. A plausible reaction mechanism is also proposed.

18.
J Org Chem ; 81(21): 10499-10505, 2016 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-27518206

RESUMO

A solvent-controlled catalyst-free chemoselective reaction was developed. Both 3,4-dihydroquinazoline-2-thiones and 2-imino[1,3]benzothiazines could be efficiently constructed by the reaction of 2-amino chalcones with isothiocyanates via two different chemoselective reactions depending on the solvents. The reaction was modulated by the solvents to proceed via either aza-Michael addition or thia-Michael addition as the major reaction with excellent yields.

19.
Beilstein J Org Chem ; 12: 253-9, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26977184

RESUMO

A new and efficient synthetic method to obtain fully-substituted hexahydroisoindolinones was developed by using bifunctional tertiary amine-thioureas as powerful catalysts. As far as we know, there is no efficient synthetic method developed toward fully-substituted hexahydroisoindolinones. The products were obtained in good yield and diastereoselectivity. The one-pot cascade quadruple protocol features readily available starting materials, simple manipulation, mild conditions and good atom economy.

20.
Chem Asian J ; 11(6): 834-8, 2016 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-26812234

RESUMO

The enantioselective construction of a spirocyclic quaternary stereogenic carbon center at the C2 position of indole has long been an elusive problem in organic synthesis. Herein, by employing a rationally designed hydrogen-bonding network activation strategy, for the first time, 2,2'-pyrrolidinyl-spirooxindole, which is a valuable and prevalent indole alkaloid scaffold, was directly obtained through a catalytic asymmetric [3+2] cycloaddition reaction with high yields and excellent stereoselectivities.


Assuntos
Reação de Cicloadição , Indóis/química , Catálise , Ligação de Hidrogênio , Estereoisomerismo
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