Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 48
Filtrar
1.
Chemistry ; 30(10): e202303832, 2024 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-38085495

RESUMO

A novel method to prepare asymmetric amine ethers is reported. Tertiary amine alcohol hydrogen sulfate intermediates are prepared through a reactive distillation process, followed by the transesterification process to afford eventually asymmetric amine ethers. Experiments and DFT calculations revealed the essential roles the sulfate group plays in the highly selective monoesterification process. This clean method is tolerant towards various functional groups with good yields under mild condition, which is obviously superior compared to the conventional processes.

2.
Sensors (Basel) ; 24(10)2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38793958

RESUMO

Ion mobility spectrometry (IMS) has been widely studied and applied as an effective analytical technology for the on-site detection of volatile organic compounds (VOCs). Despite its superior selectivity compared with most gas sensors, its limited dynamic range is regarded as a major drawback, limiting its further application in quantitative measurements. In this work, we proposed a novel sample introduction method based on pulsed membrane adsorption, which effectively enhanced IMS's ability to measure analytes at higher concentrations. Taking N-methyl-2-pyrrolidone (NMP) as an example, this new sampling method expanded the dynamic range from 1 ppm to 200 ppm. The working principle and measurement strategy of this sampling method were also discussed, providing new insights for the design and application of IMS-based instruments.

3.
Org Biomol Chem ; 20(36): 7221-7225, 2022 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-36053155

RESUMO

A new synthetic methodology for the synthesis of 5H-dibenzo[a,d]cycloheptenes from ortho-aryl alkynyl benzyl alcohols and arenes via a Tf2O-mediated formal [5 + 2] annulation reaction has been achieved. From this transformation, structurally diverse 5H-dibenzo[a,d]cycloheptenes were achieved in moderate to good yields. This transformation probably involves an intermolecular Friedel-Crafts-type alkylation and a subsequent intramolecular 7-endo-dig cyclization in one pot, highlighting the high efficiency, regioselectivity, and step-economy of this protocol.

4.
Curr Microbiol ; 79(11): 319, 2022 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-36121514

RESUMO

The aim of this study was to evaluate the effects of Lactiplantibacillus plantarum SCS4 (L. plantarum SCS4) on oxidative stress in streptozocin-induced hyperglycemic mice. After establishment of the hyperglycemic model, control group mice were gavaged daily with phosphate-buffered saline, while different experimental groups (AG, BG, and CG) mice were gavaged with L. plantarum SCS4 suspension, cellular inclusion suspension, and inactivated inclusion suspension for 10 weeks, respectively. Compared with the model group (MG) group, the results showed that fasting blood glucose levels in BG and CG groups decreased, and postprandial 2-h blood glucose levels in BG groups decreased, whereas glucose tolerance improved. Meanwhile, ROS and MDA levels in serum of AG mice were decreased significantly (P < 0.05). Compared with the MG group, serum levels of GPx, HO-1, and NQO1 were increased in the BG group, whereas serum levels of CAT, HO-1, and GSH were increased in the CG group. Our results indicate that L. plantarum SCS4 can alleviate oxidative stress induced by hyperglycemia, and there may be synergistic effects among the different treatments.


Assuntos
Glicemia , Hiperglicemia , Animais , Camundongos , Estresse Oxidativo , Fosfatos , Espécies Reativas de Oxigênio , Estreptozocina/farmacologia
5.
Zhongguo Zhong Yao Za Zhi ; 46(18): 4601-4614, 2021 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-34581068

RESUMO

The study aims to analyze the outcome indicators of randomized controlled trial(RCT) of traditional Chinese medicine(TCM) in the treatment of hypertensive intracerebral hemorrhage(HICH) in recent three years, and thus provide suggestions for the future studies in this field. Four English databases, four Chinese databases and two online registration websites of clinical trials were searched. The RCTs published between January 2018 and September 2020 were screened. The risk of bias was assessed and outcome measures were classified. A total of 151 839 articles were retrieved, of which 44 RCTs were included for analysis after screening. The outcome measures of the included RCTs were classified into 7 categories, among which the symptoms/signs category showed the highest reporting rate. National Institute of Health stroke scale(72.73%) was the most frequently reported outcome indicator, while the vo-lume of intracerebral hemorrhage determined by computerized tomography(36.36%) was the most frequently reported lab test outcome. Most studies collect the outcomes at the end of treatment, while 9 studies reported long-term outcomes 3 months or more after onset. Compared with those of international clinical trials, the application of some of the outcomes was reasonable, focusing on patients' symptoms, quality of life and objective outcomes. However, there were still several problems: unclear primary and secondary outcome measures, insufficient attention to long-term prognosis, insufficient attention to social function, few TCM outcomes, lack of measurement blindness and the use of unreasonable composite outcomes. It is recommended that researchers should rationally design the outcome indicators of clinical trials and develop the core outcome set.


Assuntos
Medicamentos de Ervas Chinesas , Hemorragia Intracraniana Hipertensiva , Medicamentos de Ervas Chinesas/uso terapêutico , Humanos , Hemorragia Intracraniana Hipertensiva/tratamento farmacológico , Medicina Tradicional Chinesa , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto
6.
Neurol Res ; : 1-10, 2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38873922

RESUMO

OBJECTIVE: The association between herpes zoster (HZ) and stroke has been the subject of much previous research. Nevertheless, the connection remains ambiguous. A two-sample Mendelian randomisation study was conducted to explore the potential causal link between HZ and ischaemic stroke, including its subtypes. METHODS: For our MR analysis, we identified genetic instrumental variables related to both HZ and stroke by screening two prominent publicly accessible genome-wide association study databases. The primary approach involved using the inverse variance weighting method. To supplement this, we also employed methods such as MR-Egger regression, the weighted median approach, simple and weighted models. Lastly, to ascertain the stability and reliability of the results, we conducted tests for heterogeneity detection, horizontal pleiotropy assessment, and a leave-one-out analysis. RESULTS: The genetically predicted HZ did not indicate an association with stroke risk ([OR] 1.041; 95% [CI] 0.958-1.131;p = 0.336). This lack of association also held true for different subtypes of stroke: ischaemic stroke (OR = 1.047, 95% CI = 0.955-1.148, p = 0.323), large vessel stroke (OR = 1.13, 95% CI = 0.90-1.41, p = 0.272), cardioembolic stroke (OR = 1.020, 95% CI = 0.859-1.211, p = 0.816), small vessel stroke (OR = 1.14, 95% CI = 0.93-1.40, p = 0.195), and lacunar stroke (OR = 1.195, 95% CI = 0.967-1.476, p = 0.097). CONCLUSION: This MR study showed that not uncover a causal link between herpes zoster and ischaemic stroke. Additional research will be necessary in the future to shed light on the fundamental mechanisms involved.

7.
Foods ; 13(7)2024 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-38611374

RESUMO

During the production process of refined betel nuts in China, a large amount of processing by-product, betel nut waste seeds, is generated. Betel nut waste seeds are rich in bioactive elements, but they have not been effectively utilized yet. In this study, an ultrasonic-assisted deep eutectic solvent method (DES) was used to selectively extract α-glucosidase inhibitors from waste seeds. Compared with traditional extraction solvents such as water and ethanol, the extraction efficiency of specific DESs is higher, and the content of alkaloids in the extracts is lower. However, it should be noted that some pure DESs exhibit inhibitory activity towards α-glucosidase. DESs, based on choline chloride/urea, were selected due to the high extraction efficiency of α-glucosidase inhibitors and their low alkaloid content as well as low inhibitory activity. The optimal extraction conditions were determined using single-factor experiments as follows: 30% (v/v) water content, a choline chloride/urea ratio of 5:3, a solid-liquid ratio of 1:10, extraction temperature of 40 °C, and a duration of 30 min. Through recovery experiments, it was found that the DES can be reused four times under these conditions, maintaining an inhibition rate comparable to alcohol extraction methods. The IC50 value of the extract was measured at 0.0066 mg/mL, superior to acarbose. In summary, this research has successfully developed an efficient and selective method for extracting α-glucosidase inhibitors from betel nut waste seeds, thereby presenting a promising avenue for future applications.

9.
Artigo em Inglês | MEDLINE | ID: mdl-36818231

RESUMO

The herbal pairing of Huangqi and Dangshen (HD) is traditional Chinese herbal medicine and has been widely used in China, especially to treat myasthenia gravis (MG). However, the mechanism of HD on MG is unclear. Aim of the Study. This study aims to investigate HD's possible role in MG treatment. Materials and Methods. The TCMSP database was used to identify the active chemicals and their targets. The GeneCards, DisGeNET, and OMIM databases were used to search for MG-related targets. The STRING database was employed in order to identify the common PPI network targets. We next utilised Cytoscape 3.8.2 for target identification and the DAVID database for gene ontology (GO) function analysis as well as Encyclopaedia of Genomes (KEGG) pathway enrichment analysis on the selected targets. The AutoDock Vina software was used to test the affinity of essential components with the hub gene before concluding that the primary targets were corrected through molecular docking. Results. 41 active compounds were screened from HD, and the number of putative-identified target genes screened from HD was 112. There were 21 target genes that overlapped with the targets of MG, which were postulated to be potential treatment targets. Through further analysis, the results showed that the active compounds from HD (such as 7-methoxy-2-methylisoflavone, quercetin, luteolin, Kaempferol, and isorhamnetin) may achieve the purpose of treating MG by acting on some core targets and related pathways (such as EGFR, FOS, ESR2, MYC, ESR1, CASP3, and IL-6). Molecular docking findings demonstrated that these active molecules have a near-perfect ability to attach to the primary targets. Conclusion. Through network pharmacology, the findings in this study provide light on the coordinated action of several HD formula components, targets, and pathways. It provided a theoretical basis for further study of HD pharmacological action.

10.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 4): o949, 2012 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-22590011

RESUMO

The title compound, C(6)H(7)O(2)S(3) (+)·BF(4) (-), consists of a planar 2-thioxo-1,3-dithiol-4,5-yl unit [maximum deviation from the ring plane = 0.020 (3) Å], with an ethyl-enedi-oxy group fused at the 4,5-positions; the ethyl-enedi-oxy C atoms are disordered over two positions with site-occupancy factors of 0.5. The 1,4-dioxine ring has a twist-chair conformation. Weak cation-anion S⋯F inter-actions [3.022 (4)-3.095 (4) Å] and an S⋯O [3.247 (4) Å] inter-action are present.

11.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 2): o432, 2012 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-22347045

RESUMO

In the title compound, C(8)H(5)NOS(2), the non-H atoms are approximately coplanar [maxium deviation = 0.060 (3) Å]. The dihedral angle between the least-squares planes of the pyridine and 1,3-dithiol-2-one rings is 5.96 (17)°. The crystal packing is stabilized by weak inter-molecular C-H⋯O hydrogen bonds and by an S⋯S close contact [3.510 (5) Å].

12.
Front Psychol ; 13: 881294, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35874407

RESUMO

We built a livestreaming impulsive buying model based on stimulus-organism-response (SOR) theory, and we explored the impact of atmospheric cues (ACELS) and sales promotion (SPELS) on impulsive buying (IBI) based on emotions (EOC) and Zhong Yong tendency (ZYT) of online consumers. Combined with holistic orientation, perspective integration, and harmony maintenance, ZYT is a cognitive process involving individual events. We gathered 478 samples using a questionnaire to test the proposed research model. The empirical findings show that as the stimuli in the livestreaming environment, ACELS and SPELS during livestreaming greatly boost EOC while significantly constraining consumers' ZYT. Among online consumers, positive EOC promotes IBI, whereas ZYT dampens it. In addition, EOC and ZYT mediate the relationship between stimulus factors and response factors in parallel, resulting in four model mediation paths. By incorporating the SOR model, this study provides theoretical underpinnings for the role of cognitive processing in impulsive purchases, as well as useful guidance for e-commerce platforms and streamers to effectively understand Chinese consumers' purchase behavior, which benefits the development of effective promotion strategies and the creation of powerful marketing tools.

13.
Am J Transl Res ; 14(3): 1714-1720, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35422918

RESUMO

OBJECTIVE: To compare the clinical efficacy, safety, and prognosis of full-threaded headless cannulated compression screws (HCCSs) and anatomical plates (APs) in the treatment of triplane fractures of the distal tibia. METHODS: In this retrospective study, 74 patients with triplane fractures of the distal tibia treated in our hospital from April 2017 to March 2019 were selected as the research subjects. Among them, 38 patients receiving full-threaded HCCSs were assigned to the research group (RG), and the remaining 36 patients receiving APs were assigned to the control group (CG). The general indices, including operation, fracture healing, and ambulation times, efficacy, and complications were recorded and compared between the two groups. Visual analogue scale (VAS) was applied to assess pain, and a quality of life (QOL) survey was conducted at 6 months after surgery. RESULTS: Compared with the CG, the operation time, fracture healing time, and ambulation time of the RG were significantly shortened (P<0.05). The proportion of patients with excellent and good outcomes and Mazur Scores in the RG were higher than those in the CG (P<0.05). The frequency of complications in the RG was lower than that in the CG (P<0.05). The preoperative VAS score did not exhibit significant differences between the two groups (P<0.05), but the scores in the RG at T1 and T2 were significantly lower than those in the CG (P<0.001). The QOL score in the RG (76.17±8.57) was also significantly higher than in the CG (71.54±8.02) (P<0.05). CONCLUSION: Full-threaded HCCSs are more effective and safer than APs and can effectively improve the prognosis of patients with triplane fractures of the distal tibia.

14.
Medicine (Baltimore) ; 101(50): e32285, 2022 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-36550924

RESUMO

BACKGROUND: Myasthenia gravis (MG) is an autoimmune disease related to the production of autoantibodies. It is mediated by antibodies against acetylcholine receptor (AChR), muscle specific kinase (MuSK) or other AChR related proteins in the postsynaptic muscle membrane, which interfere with the transmission of signals at the neuromuscular junction, resulting in clinical symptoms of skeletal muscle weakness and fatigue, leading to the occurrence and development of MG. At present, the incidence rate of Mg is increasing year by year. At present, the method of invigorating spleen, replenishing qi and tonifying kidney in traditional Chinese medicine has been widely used in the clinical treatment of MG, and the effect is good. The purpose of this study was to systematically evaluate the efficacy and safety of the method of invigorating the spleen, supplementing qi and tonifying the kidney in the treatment of MG. METHODS: We will search from the following eight databases: PubMed, Cochrane Library, EMBASE, Web of Science, CNKI, Sinomed, Wanfang, and Vip. All randomized controlled trial (RCT) literature has been searched and classified since the establishment of the database to date. In this study, two researchers independently screened and evaluated the quality of the retrieved literature. Cochrane risk bias assessment tool was used to evaluate the risk of bias. The meta-analysis uses RevMan 5.3 software provided by Cochrane Collaboration Network for meta analysis. RESULTS: This study compared the main outcome indicators: clinical response rate, recurrence rate, incidence of adverse reactions, quantitative myasthenia gravis score (QMG). Secondary outcomes were clinical absolute score, quality of life score (QOL), levels of inflammatory factors such as IL-6, IL-10, and serum acetylcholine receptor antibody (AChR-Ab) levels. CONCLUSION: The purpose of this study was to evaluate the efficacy and safety of the method of invigorating the spleen, supplementing qi and tonifying the kidney in treating MG, and to provide evidence based medicine.


Assuntos
Miastenia Gravis , Baço , Humanos , Rim , Medicina Tradicional Chinesa/métodos , Metanálise como Assunto , Miastenia Gravis/tratamento farmacológico , Qi , Receptores Colinérgicos , Revisões Sistemáticas como Assunto
15.
J Neurosci ; 30(45): 15210-20, 2010 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-21068326

RESUMO

H(+) extrusion is important for sustained NADPH oxidase activation after "respiratory" burst in macrophage/microglia activation. In this study, we investigated the role of Na(+)/H(+) exchanger isoform 1 (NHE-1) in activation of microglia after lipopolysaccharide (LPS) or oxygen and glucose deprivation and reoxygenation (OGD/REOX) exposure. NHE-1 functioned in maintaining basal pH(i) of immortalized M4T.4 microglia or mouse primary microglia. Pharmacological inhibition of NHE-1 activity with the potent inhibitor cariporide [HOE 642 (4-isopropyl-3-methylsulfonyl-benzoyl-guanidine-methanesulfonate)] abolished pH(i) regulation in microglia under basal conditions. Activation of microglia either by LPS, phorbol myristate acetate, or OGD/REOX accelerated pH(i) regulation and caused pH(i) elevation, which was accompanied with an increase in [Na(+)](i) and [Ca(2+)](i) as well as production of superoxide anion and cytokines. Interestingly, inhibition of NHE-1 not only abolished pH(i) regulation but also reduced production of superoxide anion as well as expression of cytokines and inducible nitric oxide synthase. Together, these results reveal that there was a concurrent activation of NHE-1 in microglia in response to proinflammatory stimuli. The study suggests that NHE-1 functions to maintain microglial pH(i) homeostasis allowing for sustained NADPH oxidase function and "respiratory" burst.


Assuntos
Encéfalo/metabolismo , Homeostase/fisiologia , Microglia/metabolismo , Trocadores de Sódio-Hidrogênio/metabolismo , Animais , Western Blotting , Encéfalo/citologia , Encéfalo/efeitos dos fármacos , Cálcio/metabolismo , Linhagem Celular , Células Cultivadas , Imunofluorescência , Glucose/deficiência , Guanidinas/farmacologia , Hipóxia/metabolismo , Lipopolissacarídeos/farmacologia , Camundongos , Microglia/citologia , Microglia/efeitos dos fármacos , NADPH Oxidases/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Explosão Respiratória/fisiologia , Sulfonas/farmacologia
16.
J Biol Chem ; 285(45): 35155-68, 2010 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-20817726

RESUMO

Neuronal dendrites are vulnerable to injury under diverse pathological conditions. However, the underlying mechanisms for dendritic Na(+) overload and the selective dendritic injury remain poorly understood. Our current study demonstrates that activation of NHE-1 (Na(+)/H(+) exchanger isoform 1) in dendrites presents a major pathway for Na(+) overload. Neuronal dendrites exhibited higher pH(i) regulation rates than soma as a result of a larger surface area/volume ratio. Following a 2-h oxygen glucose deprivation and a 1-h reoxygenation, NHE-1 activity was increased by ∼70-200% in dendrites. This elevation depended on activation of p90 ribosomal S6 kinase. Moreover, stimulation of NHE-1 caused dendritic Na(+)(i) accumulation, swelling, and a concurrent loss of Ca(2+)(i) homeostasis. The Ca(2+)(i) overload in dendrites preceded the changes in soma. Inhibition of NHE-1 or the reverse mode of Na(+)/Ca(2+) exchange prevented these changes. Mitochondrial membrane potential in dendrites depolarized 40 min earlier than soma following oxygen glucose deprivation/reoxygenation. Blocking NHE-1 activity not only attenuated loss of dendritic mitochondrial membrane potential and mitochondrial Ca(2+) homeostasis but also preserved dendritic membrane integrity. Taken together, our study demonstrates that NHE-1-mediated Na(+) entry and subsequent Na(+)/Ca(2+) exchange activation contribute to the selective dendritic vulnerability to in vitro ischemia.


Assuntos
Cálcio/metabolismo , Proteínas de Transporte de Cátions/metabolismo , Dendritos/metabolismo , Homeostase , Hidrogênio/metabolismo , Trocadores de Sódio-Hidrogênio/metabolismo , Sódio/metabolismo , Animais , Hipóxia Celular , Células Cultivadas , Dendritos/patologia , Concentração de Íons de Hidrogênio , Transporte de Íons , Camundongos , Proteínas Quinases S6 Ribossômicas 90-kDa/metabolismo , Trocador 1 de Sódio-Hidrogênio
17.
Adv Colloid Interface Sci ; 287: 102299, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33321331

RESUMO

Water is the universal solvent in nature to catalyze the biological transformation processes. However, owing to the immiscibility of many reagents in water, synthesis chemistry relies heavily on organic solvent. Micellar media is a green alternative to traditional petroleum feedstock derived solvents, which is recently attracting increasing research attention. The present review deals with the recent advances in micellar catalysis with an emphasis on the new "tailor-made" surfactants for various reactions. A brief overview of commercial surfactants, including anionic micelles, cationic micelles, and nonionic micelles is presented. More importantly, an attempt was made to discuss systematically the recent research progress on new surfactants by introducing structures, micellar effects and recycling process, aiming to serve as the basis for future development of surfactants.

18.
ACS Omega ; 6(7): 5074, 2021 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-33644616

RESUMO

[This corrects the article DOI: 10.1021/acsomega.0c04188.].

19.
J Neurochem ; 112(1): 173-82, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19840218

RESUMO

In this study, we investigated whether disruption of Na(+) and Ca(2+) homeostasis via activation of Na(+)-K(+)-Cl(-) cotransporter isoform 1 (NKCC1) and reversal of Na(+)/Ca(2+) exchange (NCX(rev)) affects protein aggregation and degradation following oxygen-glucose deprivation (OGD). Cultured cortical neurons were subjected to 2 h OGD and 1-24 h reoxygenation (REOX). Redistribution of ubiquitin and formation of ubiquitin-conjugated protein aggregates occurred in neurons as early as 2 h REOX. The protein aggregation progressed further by 8 h REOX. There was no significant recovery at 24 h REOX. Moreover, the proteasome activity in neurons was inhibited by 80-90% during 2-8 h REOX and recovered partially at 24 h REOX. Interestingly, pharmacological inhibition or genetic ablation of NKCC1 activity significantly decreased accumulation of ubiquitin-conjugated protein aggregates and improved proteasome activity. A similar protective effect was obtained by blocking NCX(rev) activity. Inhibition of NKCC1 activity also preserved intracellular ATP and Na(+) homeostasis during 0-24 h REOX. In a positive control study, disruption of endoplasmic reticulum Ca(2+) with thapsigargin triggered redistribution of free ubiquitin and protein aggregation. We conclude that overstimulation of NKCC1 and NCX(rev) following OGD/REOX partially contributes to protein aggregation and proteasome dysfunction as a result of ionic dysregulation.


Assuntos
Cálcio/fisiologia , Proteínas de Membrana Transportadoras/metabolismo , Neurônios/metabolismo , Sódio/fisiologia , Animais , Cátions Bivalentes/antagonistas & inibidores , Cátions Bivalentes/metabolismo , Cátions Monovalentes/antagonistas & inibidores , Cátions Monovalentes/metabolismo , Hipóxia Celular/fisiologia , Células Cultivadas , Feminino , Glucose/deficiência , Homeostase/genética , Homeostase/fisiologia , Hipóxia/metabolismo , Proteínas de Membrana Transportadoras/fisiologia , Camundongos , Neurônios/fisiologia , Gravidez , Complexo de Endopeptidases do Proteassoma/fisiologia , Inibidores de Proteassoma , Dobramento de Proteína , Multimerização Proteica , Simportadores de Cloreto de Sódio-Potássio/deficiência , Simportadores de Cloreto de Sódio-Potássio/genética , Simportadores de Cloreto de Sódio-Potássio/metabolismo , Membro 2 da Família 12 de Carreador de Soluto
20.
ACS Omega ; 5(46): 29903-29912, 2020 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-33251426

RESUMO

The reaction of magnesium or zinc amides with alkyl or benzyl halides is an attractive approach to make C-N bonds, especially for electron-poor organic halides. The magnesium-promoted preparation of hindered non-nucleophilic amine (N,N-diisopropylethylamine) from ethyl chloride and zinc diisopropylamide has been studied. In this paper, instead of the application scope of this method, we focused on the mechanisms of the catalytic processes and the associated electronic origins. According to the calculations, the C-N coupling process in all selected systems proceed preferably in an ethylium-transfer mode. Further, rather than undergoing the Grignard reaction route, the more pronounced electronic interactions within the transition structure as induced by the "innocent" magnesium atom should be responsible for the observed high catalytic activity of the Mg/ZnCl2 combination.

SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa