RESUMO
A photocatalytic three-component reaction of a nitroarene, a thiophenol, and a ketone for the synthesis of multifunctional diaryl sulfides was reported using a nitro group as the nitrogen source and thiophenol as the sulfur source. Thiophenol also serves as a proton donor to reduce nitroarene to arylamine as a key intermediate for the formation of C-N and C-S bonds. Good functional group tolerance and mild reaction conditions make this method have practical synthetic value for diversified multifunctional diaryl sulfides.
RESUMO
We present an efficient and versatile visible light-driven methodology for synthesizing sulfinamides and sulfoxides using nitroarenes as the nitrogen source and thiophenols as the sulfur source. The switch-over of the two reaction pathways was achieved by changing the type of photocatalyst and the amount of thiophenol in the reaction mixture. The reaction proceeds under mild conditions with good functional group tolerance and can easily be scaled up.
RESUMO
We present an efficient and versatile visible light-driven methodology to transform aryl aldehydes and ketones chemoselectively either to alcohols or to pinacol products with CdSe/CdS core/shell quantum dots as photocatalysts. Thiophenols were used as proton and hydrogen atom donors and as hole traps for the excited quantum dots (QDs) in these reactions. The two products can be switched from one to the other simply by changing the amount of thiophenol in the reaction system. The core/shell QD catalysts are highly efficient with a turn over number (TON) larger than 4 × 104 and 4 × 105 for the reduction to alcohol and pinacol formation, respectively, and are very stable so that they can be recycled for at least 10 times in the reactions without significant loss of catalytic activity. The additional advantages of this method include good functional group tolerance, mild reaction conditions, the allowance of selectively reducing aldehydes in the presence of ketones, and easiness for large scale reactions. Reaction mechanisms were studied by quenching experiments and a radical capture experiment, and the reasons for the switchover of the reaction pathways upon the change of reaction conditions are provided.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Cardiomegalia/prevenção & controle , Hidroxietilrutosídeo/análogos & derivados , Isoproterenol/efeitos adversos , Serina-Treonina Quinases TOR/metabolismo , Animais , Anticoagulantes/farmacologia , Cardiomegalia/induzido quimicamente , Hidroxietilrutosídeo/farmacologia , RatosRESUMO
A chemical investigation of the 80% EtOH extract of the aerial plant of Alstonia rupestris afforded four new monoterpenoid indole alkaloids, 6,7-epoxy-8-oxo-vincadifformine (1), 11-acetyl-6,7-epoxy-8-oxo-vincadifformine (2), 11-hydroxy-14-chloro-15-hydroxy-vincadifformine (3), and perakine N1,N4-dioxide (4), together with two known compounds, 11-hydroxy-6,7-epoxy-8-oxovincadifformine (5) and vinorine N1,N4-dioxide (6). Structural elucidation of all the compounds was performed by spectral methods such as 1D- and 2D-NMR, IR, UV, and HRESIMS. Alkaloids 1, 2 and 5 showed significant cytotoxicities against all the tested tumor cell lines of the head and neck squamous cell carcinoma with IC50 value less than 20 µM and antimicrobial activities against two fungi (Alternaria alternata and Phytophthora capsici). Alkaloids 4 and 6 exhibited the activity against bacterium Staphylococcus aureus.
Assuntos
Alstonia/química , Antibacterianos/isolamento & purificação , Antifúngicos/isolamento & purificação , Antineoplásicos Fitogênicos/isolamento & purificação , Alcaloides de Triptamina e Secologanina/isolamento & purificação , Antibacterianos/química , Antifúngicos/química , Antineoplásicos Fitogênicos/química , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Alcaloides de Triptamina e Secologanina/químicaRESUMO
Three new tirucallane triterpenoids, 3ß,16-dihydroxy-25-hydroperoxytirucalla-7,23(24)-dien-6-oxo acid (1), 3ß,16ß-hydroxytirucalla-7,24(25)-dien-21,23-olide (2), and 3ß,16ß-hydroxytirucalla-7,24(25)-dien-6-oxo-21,23-olide (3) were isolated from the 70% ethanol extract of the stem bark of Melia toosendan. Their structures were determined on the basis of 1D and 2D NMR (COSY, HMQC, HMBC and NOESY) analyses. The isolated compounds were evaluated in vitro for cytotoxic activities against A549, SK-OV-3, SK-MEL-2 and HCT15 tumor cell lines. Compounds 2 and 3 exhibited significant cytotoxic activities against the four tested cell lines with IC(50) values of 3.4-5.7 µg/mL and 3.2-5.0 µg/mL, respectively.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Melia/química , Neoplasias/tratamento farmacológico , Triterpenos/farmacologia , Antineoplásicos Fitogênicos/administração & dosagem , Linhagem Celular Tumoral , Humanos , Concentração Inibidora 50 , Espectroscopia de Ressonância Magnética , Neoplasias/patologia , Casca de Planta , Extratos Vegetais/administração & dosagem , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Caules de Planta , Terpenos , Triterpenos/administração & dosagem , Triterpenos/isolamento & purificaçãoRESUMO
An investigation of EtOAc extracts of Kadsura coccinea (Lem.) A. C. Smith, has led to the isolation of two new compounds characterized as 3-hydroxy-12-hydroxyl coccinic acid (1) and 3-hydroxy-neokadsuranic acid A (2). Their structures were established by 1D and 2D NMR techniques and mass spectroscopy. Antiproliferative effects of the isolated compounds were evaluated against four human tumor cell lines (A549, HCT116, HL-60 and HepG2), and it was found that compound 1 exhibited antiproliferative effects with IC(50) values ranging from 3.01 to 18.08 µg/mL.