RESUMO
A BF3·OEt2-catalyzed cascade cyclization reaction of vinyloxirane with coumarin is described, affording the benzocoumarin derivatives with moderate to excellent yields (72-92%). The reaction demonstrates exceptional substrate tolerance and has been extensively explored for its potential in drug development, including scale-up experiments, functional group transformations, and screening of the products for anticancer activity. Moreover, the reaction mechanism has been rigorously validated through intermediate trapping and control experiments. Additionally, this reaction represents the uncommon nonmetal catalyzed intermolecular cyclization of vinyloxiranes.
RESUMO
An efficient cascade intramolecular cyclization/intermolecular nucleophilic addition reaction of allenyl benzoxazinone with isatin or isatin-derived ketimine has been established by using Pd0-π-Lewis base catalysis. A series of 3-hydroxy-2-oxindoles and 3-amino-2-oxindoles with quaternary carbon atoms at the C3 position were synthesized in good yields under mild conditions through this protocol.
RESUMO
A palladium-catalyzed [4 + 2] cycloaddition of 2-methylidenetrimethylene carbonate or methylene cyclic carbamate with sulfamate-derived cyclic imines has been successfully developed under mild reaction conditions, affording pharmacologically interesting oxazine or hydropyrimidine derivatives in high yields (up to 99% yield). Furthermore, the cycloaddition reactions could be efficiently scaled up and several synthetic transformations were accomplished for the construction of other useful 1,3-oxazine and hydropyrimidinone derivatives.
RESUMO
Commercially available compounds that can be directly used as fluorescent probes will greatly promote the development of fluorescent imaging. Based on our previously work related to nitrogen bridgehead heterocycles, herein, a commercially available compound, 6-chloroimidazo[1,2-a]pyridine-2-carboxylic acid, has been detected for monitoring pH value (3.0-7.0). The probe proves to have high selectivity and sensitivity, brilliant reversibility, and extremely short response time. The real-time imaging of pH changes in yeast was also conducted.
Assuntos
Corantes Fluorescentes , Ácidos Picolínicos , Corantes Fluorescentes/química , Concentração de Íons de HidrogênioRESUMO
Pesticide stress on plants is receiving increased scrutiny due to its effect on plant secondary metabolism and nutritional quality. Tannic acid (TA) is a natural polyphenolic compound showing excellent antioxidant properties and is involved in alleviating stress. The present study thoroughly investigated the effects and mechanism of exogenous TA on relieving imidacloprid (IMI) stress in tea plants. Our research found that TA(10 mg/L) activated the antioxidant defense system, enhanced the antioxidant ability, reduced the accumulation of ROS and membrane peroxidation, and notably promoted tea plant tolerance to imidacloprid stress. Additionally, TA boosted photosynthetic capacity, strengthened the accumulation of nutrients. regulated detoxification metabolism, and accelerated the digestion and metabolism of imidacloprid in tea plants. Furthermore, TA induced significant changes in 90 important metabolites in tea, targeting 17 metabolic pathways through extensively targeted metabolomics. Specifically, TA activated the flavonoid biosynthetic pathway, resulting in a 1.3- to 3.1-fold increase in the levels of 17 compounds and a 1.5- to 63.8-fold increase in the transcript level of related genes, such as ANR, LAR and CHS in this pathway. As a potential tea health activator, TA alleviates the oxidative damage caused by imidacloprid and improves the yield and quality of tea under pesticide stress.
Assuntos
Camellia sinensis , Praguicidas , Antioxidantes/farmacologia , Antioxidantes/metabolismo , Árvores/metabolismo , Flavonoides/farmacologia , Flavonoides/metabolismo , Vias Biossintéticas , Estresse Oxidativo , Camellia sinensis/genética , Taninos/farmacologia , Taninos/metabolismo , Chá , Praguicidas/metabolismoRESUMO
A survey was designed to investigate the pesticide residues in agricultural produce and to estimate their potential intake risks to inhabitants. A total of 314 samples of nine types of fruits and vegetables were collected from the supermarkets and vegetable markets of Shandong Province (China) from October 2020 to February 2022. An accurate and reliable multi-residue method, based on GC-MS/MS detection, as well as the multiplug filtration cleanup method, based on SBA-15-C18, was prepared by a solution chemical reaction. Additionally, an in situ co-condensation method was established for the quantification of 139 pesticide residues. Residues that contained no pesticides were detected in 66.5% of the 314 samples. Moreover, of the samples, 30.6% were at or below the MRLs, and 2.9% were above the MRLs. Residues of procymidone were found to be the one that most often exceeded the MRLs (1.3% of the samples). Tebuconazole was found most frequently in 22.0% of the samples analyzed. Consumer exposure to the 139 pesticides did not exceed 100% ADI and ARfD. This led to a consideration that these pesticide residues in the nine commodities may not raise the health risk of the consumers in the long and short term. The highest value of chronic dietary intake was obtained from spirodiclofen, which resulted in a 24.1% of ADI. Furthermore, the highest exposure levels in the short term were obtained from the consumption of leeks with procymidone (58.3% ARfD).
Assuntos
Resíduos de Praguicidas , Praguicidas , Praguicidas/análise , Resíduos de Praguicidas/análise , Espectrometria de Massas em Tandem , Cromatografia Gasosa-Espectrometria de Massas , Contaminação de Alimentos/análise , Verduras/química , Medição de Risco , Ingestão de AlimentosRESUMO
A novel cyclization of α-halogenoacetamides with 1-azadienes has been developed for the efficient preparation of monocyclic 1,4-diazepinones in one step under transition metal-free conditions. Various α-halogenoacetamides and 1-azadienes are well tolerated and give the desired products in good to excellent yields. This cyclization also demonstrates potential synthetic utility on a gram-scale and further transformation.
RESUMO
Salicylic acid (SA) is a crucial signal molecule and phytohormone, regulating the biotic and abiotic stress responses as well as plant development. In this research, we comparatively examined the effects of exogenous SA on the behaviors of thiamethoxam (THIM), hymexazol (HMI) and chlorantraniliprole (CAP) in cucumber planting systems under soil pot and hydroponic cultivation. The cucumber seedlings were transplanted into soil or nutrient solution containing a target pesticide (1 mg/kg) or a target pesticide with SA (1 mg/kg) after the fourth leaf emerged. We examined the behaviors of pesticides both the SA treated and nontreated plants by analyzing cucumber root, stem and leaf samples taken on the 0-21 days following the root treatment. The root concentration factor (RCF), bioconcentration factor (BCF) and translocation factors (TFstem and TFleaf) were calculated for the comparison of the differences in the behaviors of pesticides. We found that the accumulation behaviors of pesticides in planting systems were related to the physicochemical properties of pesticides, exogenous SA and cultivation methods. Exogenous SA had a certain promoting effect on the degradation of pesticides in soil and nutrient solution, resulting in reduced half-lives. SA was able to block the accumulation of pesticides in roots and leaves and alleviated the accumulation ability of roots, the bioconcentration ability of plants, and the translocation ability from roots to leaves. Interestingly, SA had more distinct effects on the behaviors of pesticides under hydroponic experiments than under soil pot experiments. Furthermore, the behaviors of clothianidin (CLO), the main metabolite of THIM, were also assessed, indicating that THIM was mainly metabolized to CLO in leaves and stems, and SA facilitated this process. Our findings suggest that SA has a certain regulatory effect on the accumulation of pesticides in plants, and SA-blocked pesticide accumulation is practically rewarding for improving food safety.
Assuntos
Cucumis sativus/fisiologia , Praguicidas/toxicidade , Substâncias Protetoras/farmacologia , Ácido Salicílico/farmacologia , Poluentes do Solo/toxicidade , Cucumis sativus/metabolismo , Guanidinas , Neonicotinoides , Praguicidas/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Folhas de Planta/metabolismo , Plântula/efeitos dos fármacos , Solo , Poluentes do Solo/análise , Estresse Fisiológico/efeitos dos fármacos , Tiametoxam/metabolismo , Tiazóis , ortoaminobenzoatosRESUMO
A bifunctional phosphine-catalyzed highly enantioselective [2+4] cycloaddition of α-substituted allenoates with (E)-1-benzyl-4-olefinicpyrrolidine-2,3-diones has been achieved, giving pyrrolidin-2-one fused dihydropyran derivatives in moderate to good yields with excellent enantioselectivities (up to 98% ee). This reaction provides a useful catalytic asymmetric access to dihydropyran structural motifs.
RESUMO
[4 + 3] cycloaddition of phthalazinium dicyanomethanides with in situ formed azoalkenes was achieved, providing an access to various 1,2,4-triazepine derivatives in moderate to excellent yields.
RESUMO
A palladium-catalyzed asymmetric [4 + 3] cycloaddition of the methylene-trimethylenemethane donor with an azadiene has been developed, affording benzofuro[3,2-b]azepine-derived exocyclic chiral allene with control of axial and point chirality. The target compounds were generated in good to excellent yields and with high diastereoselectivities and enantioselectivities (up to >20 : 1 dr, 99% ee). Furthermore, this cycloaddition reaction could be efficiently scaled-up and several synthetic transformations were accomplished for the construction of useful chiral allenol and chiral spirocyclic derivatives.
RESUMO
We herein designed and synthesized allenyl benzoxazinones of a novel type, which were then involved in a Pd-catalyzed asymmetric cascade intramolecular cyclization/intermolecular Michael addition reaction with 1-azadienes. A broad range of chiral C2-functionalized quinoline derivatives were afforded in moderate to good yields (up to 93%) with high enantioselectivities (up to 93% ee) in this reaction.
RESUMO
A simple and efficient cascade reaction was developed for the construction of hydroxy substituted indolizines from pyrrole-2-carbaldehydes and commercially available 4-halogenated acetoacetic esters. Their optical properties were also evaluated.
RESUMO
The metal-free DBU catalyzed [3+2] cycloaddition of 3-homoacyl coumarins with cyclic 1-azadienes proceeded smoothly to furnish the corresponding highly functionalized cyclopentane-fused coumarins with excellent diastereoselectivity and complete chemoselectivity and in good yields under mild conditions.
RESUMO
The phosphine-catalyzed tandem annulation reaction of Morita-Baylis-Hillman (MBH) alcohols with azomethine imines has been achieved for the synthesis of biologically important (epoxymethano)-pyrazolo[5,1- b]quinazoline derivatives. A variety of MBH alcohols and azomethine imines were well-tolerated under the mild reaction conditions, providing novel 3D heterocyclic compounds in high yields with excellent diastereoselectivities. It is the first time the direct activation of unmodified MBH alcohols acting as new oxa-synthons has been achieved.
RESUMO
A diastereoselective construction of biologically important tetrahydrocyclopenta[ b]naphthalene derivatives has been achieved via a phosphine-catalyzed [3 + 2] annulation of 2-hydroxy-1,4-naphthaquinone derivatives and allenoate. Various tetrahydrocyclopenta[ b]naphthalene derivatives containing contiguous quaternary carbon centers are obtained in good yields with excellent diastereoselectivities. The asymmetric version gave the chiral product in up to 57% ee under catalysis of Kwon chiral phosphine. The reaction undergoes a reaction mechanism involving consecutive γ-addition-aldol reaction.
RESUMO
In this paper, a phosphine-catalyzed [8 + 2]-annulation of heptafulvene with allenoates has been achieved under mild conditions, giving functionalized bicyclo[5.3.0]decane derivatives in moderate to excellent yields. Using chiral phosphine as the catalyst, optically active products were obtained in moderate to high yields with excellent enantioselectivities.
RESUMO
A multifunctional chiral phosphine-catalyzed enantioselective [3+2] annulation of Morita-Baylis-Hillman carbonates with cyclopentenones provides a direct approach to access functional 4-oxo-1,3a,4,5,6,6a-hexahydropentalene compounds. Moderate to good yields and excellent enantioselectivities (>90% ee) were obtained for a series of substrates under mild reaction conditions.
RESUMO
A palladium-catalyzed enantioselective [4 + 2] cycloaddition reaction of vinyl benzoxazinones with sulfamate-derived cyclic imines is described, affording the tetrahydroquinazolines bearing several functional rings in high yields (up to 99% yield) with good to excellent diastereoselectivities and excellent enantioselectivities (up to 96% ee). This reaction represents the first Pd-catalyzed asymmetric decarboxylative cycloaddition of vinyl benzoxazinones with imines.