RESUMO
Herein, a versatile highly regioselective three-component annulation of simple aromatic ketones and methylamines using a hypervalent iodine reagent for polyarylated 1-pyrrolines has been described in good to excellent yields. Meanwhile, unsymmetrical 1-pyrroline isomers could be realized and synthesized. Such an intriguing one-pot two-step tandem assembly strategy with green conditions and high regioselectivity shows predictable inspiration in related annulation reactions.
RESUMO
A pyrrolo[2,1-a]isoquinoline core structure is prevalent in marine and other natural products. This article describes a tungsten-catalyzed [3+2] cycloaddition aromatization of dihydroisoquinoline ester and maleic anhydride or an acrylate. The photochemical reaction tolerates a range of functional groups such as ester, cyano, ketone, bromide, and alkene. It is shown that the cycloaddition-aromatization of 2-substitued acrylate catalyzed by a tungsten photocatalyst can be used to evaluate the leaving ability of the leaving group. Experiments done to determine the reaction mechanism revealed that the formation of an ion-pair intermediate generated in situ from dihydroisoquinoline ester and (Z)-4-methoxy-4-oxobut-2-enoic acid via the solvolysis of maleic anhydride with methanol is crucial for the cascade process to occur. The key cycloadduct acid intermediate derived from [3+2] cycloaddition was isolated and determined by X-ray crystallography.
RESUMO
Difluoromethylated compounds usually act as bioisosteres for alcohol functional groups and show unique physicochemical and biological properties. The cyano-difluoromethylation of alkenes using 5-((difluoromethyl)sulfonyl)-1-phenyl-1H-tetrazole as a CF2H radical difluoromethyl precursor was developed to afford nitriles including a CF2H group. A low-cost, stable, easily handled 5-((difluoromethyl)sulfonyl)-1-methyl-1H-tetrazole (DFSMT) was synthesized and applied as the radical CF2H reagent. Using DFSMT as the radical CF2H precursor, the oxyl-difluoromethylation of alkenes was developed to obtain difluoromethylated ether products. All of the reactions showed good functional group tolerability. Initial mechanistic experiments indicated that the CF2H radical was involved as the key active intermediate.
RESUMO
An eco-friendly and metal-free method for the synthesis of tetrahydrodibenzo[b,g][1,8]naphthyridin-1(2H)-ones was established. Quinoline-derived dipolarophiles and cyclic enaminones as starting materials undergo a 1,4-Michael addition/SNAr tandem annulation reaction affording the target products. This approach features transition metal-free conditions, good functional group tolerance and operational simplicity.
RESUMO
With triethylamine as a 1,3-diene variant, a simple and practical process for the synthesis of phthalimides has been developed from readily available maleimide. The transformation can be performed in the absence of a metal catalyst with high levels of functional group tolerance. Various phthalimide compounds were constructed in moderate to good yields under mild conditions. Mechanism research indicates that oxygen and acid also play crucial roles in this reaction.
RESUMO
Atherosclerosis is a dominant cause of cardiovascular disease. Accumulation of low-density lipoproteins (LDL), formation of foam cells, and endothelial dysfunction within the arterial intima contribute to atherosclerotic plaque formation. Soy consumption is thought to have positive effect on the prevention of atherosclerosis. Therefore, in the present study, a novel soybean polypeptide dglycin was purified and characterized. Oral administration of 20 mg/g.d dglycin reduced 47.6 % lesion area, and 49.1 % lipid deposition in the atherosclerotic plaques in aortic roots in ApoE-/- mice. In addition, it decreased the levels of 26.0 % plasma low-density lipoprotein, 27.2 % triglyceride, 40.1 % cholesterol, 25.1 % malondialdehyde and 24.2 % tumor necrosis factor-alpha (TNFα). In vitro experiments revealed that dglycin inhibited inflammatory cytokine secretion from aortic endothelial cells via the inhibition of NF-κB signaling. Furthermore, it inhibited reactive oxygen species generation, subsequently enhanced cell viability, and protected aortic endothelial cells from necrosis and apoptosis via mitochondrial function improvement. On the other hand, dglycin prevented the uptake of oxidized LDL by macrophages via suppressing the expression of scavenger receptor class A1, which suggested that dglycin prevented foam cell formation. Therefore, dglycin alleviated the early-stage of atherosclerosis via depressing inflammation, lipid deposition, protecting aortic endothelial cells and preventing foam cell formation.
RESUMO
An environmentally friendly and transition metal-free method for the annulation of α-bromocinnamaldehydes was established. 3-Formyl-imidazo[1,2-α]pyridines and pyrimidines were obtained in moderate to excellent yields. This approach features easily available starting materials, transition metal-free conditions, good functional group tolerance and operational simplicity.
RESUMO
Herein, we disclose a practical and simple procedure to synthesize 2-aminobenzoxaoles. Simple anilines and formamides were used as substrates. The C-H bond ortho to the amino group in the anilines was directly functionalized under cobalt-catalyzed conditions with high levels of functional group tolerance. Hypervalent iodine(III) was both an oxidant and a Lewis acid for this reaction. The mechanism study showed that this transformation may involve a radical process.
RESUMO
The enantioselective addition of arylboronic acids to N-heteroaryl ketones provides a convenient access to chiral α-heteroaryl tertiary alcohols, yet addition reactions of this type have been challenging due to catalyst deactivation. In this report, an efficient rhodium-catalyzed addition of arylboronic acids to N-heteroaryl ketones is established, affording a variety of valuable α-heteroaryl alcohols with excellent functional group compatibility. The employment of the WingPhos ligand containing two anthryl groups is crucial for this transformation. In particular, a range of chiral benzoxazolyl-substituted tertiary alcohols were formed with excellent ee values and yields by employing a Rh loading as low as 0.3 mol%, which can serve as a practical protocol to furnish a series of chiral α-hydroxy acids after hydrolysis.
RESUMO
A convenient and efficient annulation reaction has been developed for the general synthesis of dinitrile-substituted cyclopropanes in moderate to excellent yields. A variety of 2-arylacetonitriles and α-bromoennitriles were compatible under the standard conditions. The reaction was achieved through tandem Michael-type addition followed by intramolecular cyclization. The preliminary application of this method was confirmed by the synthesis of the 2,4-dioxo-3-azabicyclo[3.1.0]hexane scaffold.
RESUMO
2-Styrylthiophene-based donor-acceptor linear conjugated polymers with tunable cyano substituents are atom-economically obtained via direct C-H arylation for platinum-free photocatalytic hydrogen production, affording a HER of up to 9.79 mmol h-1 g-1.
RESUMO
Iron-catalyzed oxidative synthesis of N-aryl-substituted tetrahydroisoquinolines (THIQs) toward tetrahydroisoquinoline-based derivatives is reported. A wide range of α-amino nitriles and tetrahydroisoquinolinones are synthesized in moderate to good yields. This approach involves a new organic nitrile source, a cheap iron catalyst under an oxygen atmosphere, and temperature-controlled divergent synthesis and features complete selectivity and operational simplicity.
Assuntos
Ferro , Nitrilas , Catálise , Estrutura Molecular , OxirreduçãoRESUMO
Hesperetin is a class of natural products with a wide range of sources and remarkable biological activities. In this study, we described the synthesis of a series of novel hesperetin derivatives and evaluated the in vitro antioxidant and antitumor activity of these compounds. Eleven novel compounds were synthesized in moderate yields. The compounds synthesized in this work exhibited antioxidant activities against DPPH and ABTS free radicals in a dose-dependent manner. Among them, compound 3f had the best antioxidant activity, with IC50 of 1.2 µM and 24 µM for DPPH and ABTS, respectively. The antitumor activity of the compounds against human cancer cell lines, such as breast MCF-7, liver HepG2, and cervical Hela, was determined by a standard 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay. Three compounds had moderate IC50 values. Interestingly, compound 3f had better biological activity than hesperetin, which matches the prediction by Maestro from Schrödinger. Therefore, the new hesperidin derivative is a promising drug for the treatment of cancer due to its effective antitumor activity. The results also suggested that the antitumor activities of hesperetin derivatives may be related to their antioxidant activities.
Assuntos
Antineoplásicos , Antioxidantes , Hesperidina , Neoplasias/tratamento farmacológico , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/farmacologia , Antioxidantes/síntese química , Antioxidantes/química , Antioxidantes/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Células HeLa , Células Hep G2 , Hesperidina/síntese química , Hesperidina/química , Hesperidina/farmacologia , Humanos , Células MCF-7 , Neoplasias/metabolismoRESUMO
An efficient formal alkenyl C-H cyanation reaction has been developed for the general synthesis of unsymmetrical diarylfumaronitriles in good to excellent yields. The reaction was achieved through tandem Michael addition and an oxidative process. The merits of this transformation include the use of K3Fe(CN)6 as a safe and nontoxic cyanide source, without an external noble metal catalyst, oxygen-involved reactions, easily available raw materials, good functional group tolerance, high stereoselectivity, and potential further application of the products.
RESUMO
A novel catalyst-free radical oxidative C-H annulation reaction of arylamines with α-keto acids toward benzoxazin-2-ones synthesis under mild conditions was developed. This hypervalent iodine(III)-promoted process eliminated the use of a metal catalyst or additive with high levels of functional group tolerance. Hypervalent iodine(III) was both an oxidant and a radical initiator for this reaction. The synthetic utility of this method was confirmed by the synthesis of the natural product cephalandole A.
Assuntos
Iodo , Catálise , Cetoácidos , Oxirredução , Estresse OxidativoRESUMO
An efficient nano-Cu2O-catalyzed cascade multicomponent reaction of 2-halobenzoic acids and trimethylsilyl cyanide with diverse amines was developed using water as a solvent, affording versatile N-substituted phthalimide derivatives in moderate to excellent yields. This novel strategy features carbon monoxide gas-free, environmentally benign, one-pot multistep transformation, commercially available reagents, a cheap catalyst without any additives, wide functional group tolerance, and operational convenience.
RESUMO
A novel formal [3+2] and [4+2] annulation of ketoxime acetates and ynals for the synthesis of pyrroles and isoquinolines has been developed. By simply switching the catalyst and solvent, the reaction proceeds via two pathways. The reactions are achieved under mild conditions with broad substrate scope and excellent regioselectivity.
RESUMO
Cu-catalyzed domino decyanation and cyanation reaction of acyl cyanides with amines or alcohols have been developed. The cyano sources were generated in situ via C-CN cleavage yielding the corresponding cyano substituted amides or esters in moderate to excellent yields. This approach features a cheap copper catalyst, domino decyanation and cyanation reaction, readily available starting materials, broad substrate scope, operational simplicity, and the potential for further transformation of the cyano group.
RESUMO
A metal-free three-component annulation reaction for the synthesis of indolizine thiones via tandem C-C/C-N/C-S bond formation was developed. Various 2-alkylpyridines with aromatic ynals and elemental sulfur proceeded smoothly under catalyst-free conditions, and the desired products were obtained in moderate to excellent yields.
RESUMO
Novel ring-opening reactions are achieved employing benzofuroxan as a new type of iminating or aminating reagent. These diverse transformations give access to three types of molecular scaffolds, N-aryl dimethylsulfoximines, methanesulfonamides, and hemiaminal ethers, which are important structural motifs in organic and medicinal chemistry. The procedures feature solvent-involved reactions, easily available starting materials, operational simplicity, high atom economy, and the potential further transformation of nitro group.