Microwaves

微波
  • 文章类型: Journal Article
    香蕉皮,约占水果重量的35%,经常被丢弃,提出环境和经济问题。本研究的重点是通过优化先进的提取技术回收香蕉皮废物,特别是微波辅助提取(MAE)和超声辅助提取(UAE),用于分离酚类化合物。将基于氯化胆碱的深度低共熔溶剂(DES)与30%(w/w)水含量的甘油以1:3的比例与30%乙醇进行比较。参数,包括样品溶剂比(SSR),提取时间,MAE的温度或阿联酋的振幅,是多种多样的。分析提取物的羟基肉桂酸(HCA)和类黄酮含量,和使用FRAP和ABTS测定的抗氧化活性。DES优于乙醇,HCA含量为180.80至765.92mg/100g,类黄酮含量为96.70至531.08mg/100g,伴随着更高的抗氧化活性。使用DES的最佳MAE条件是SSR为1:50,温度为60°C,10分钟的时间,而SSR为1:60,时间为5分钟,75%的振幅对于阿联酋是最佳的。优化提取物的多酚谱包含19种属于黄酮醇类的单独化合物,黄烷-3-醇,和酚酸。这项研究得出的结论是,DES,凭借其优越的提取效率和环境效益,是用于从香蕉皮中提取高价值生物活性化合物的有前途的溶剂,并为食品和制药行业提供了巨大的潜力。
    Banana peels, comprising about 35% of the fruit\'s weight, are often discarded, posing environmental and economic issues. This research focuses on recycling banana peel waste by optimizing advanced extraction techniques, specifically microwave-assisted (MAE) and ultrasound-assisted extraction (UAE), for the isolation of phenolic compounds. A choline chloride-based deep eutectic solvent (DES) with glycerol in a 1:3 ratio with a water content of 30% (w/w) was compared to 30% ethanol. Parameters, including sample-to-solvent ratio (SSR), extraction time, and temperature for MAE or amplitude for UAE, were varied. Extracts were analyzed for hydroxycinnamic acid (HCA) and flavonoid content, and antioxidant activity using FRAP and ABTS assays. DES outperformed ethanol, with HCA content ranging from 180.80 to 765.92 mg/100 g and flavonoid content from 96.70 to 531.08 mg/100 g, accompanied by higher antioxidant activity. Optimal MAE conditions with DES were an SSR of 1:50, a temperature of 60 °C, and a time of 10 min, whereas an SSR of 1:60, time of 5 min, and 75% amplitude were optimal for UAE. The polyphenolic profile of optimized extracts comprised 19 individual compounds belonging to the class of flavonols, flavan-3-ols, and phenolic acids. This study concluded that DESs, with their superior extraction efficiency and environmental benefits, are promising solvents for the extraction of high-value bioactive compounds from banana peels and offer significant potential for the food and pharmaceutical industries.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    二氧化钛是通过使用溶胶-凝胶法水解异丙醇钛(IV)合成的,在中性或基本条件下,并在微波辅助溶剂热反应器和/或高温炉中加热。使用X射线衍射法测定制备的样品的相组成。通过低温氮吸附/解吸研究确定比表面积和孔体积。通过光催化还原二氧化碳测试样品的光活性。使用气相色谱法分析气相的组成,和氢,碳氧化物,甲烷被识别出来了.研究了pH和热处理对二氧化碳光还原过程中二氧化钛基材料物理化学性质的影响。发现在中性环境中制备的光催化剂显示出较高的氢含量,一氧化碳,与在基本条件下获得的光催化剂相比,气相中的甲烷。在使用在微波反应器中加热的光催化剂的过程中检测到最高量的氢气,和双重加热的光催化剂。
    Titanium dioxide was synthesized via hydrolysis of titanium (IV) isopropoxide using a sol-gel method, under neutral or basic conditions, and heated in the microwave-assisted solvothermal reactor and/or high-temperature furnace. The phase composition of the prepared samples was determined using the X-ray diffraction method. The specific surface area and pore volumes were determined through low-temperature nitrogen adsorption/desorption studies. The photoactivity of the samples was tested through photocatalytic reduction of carbon dioxide. The composition of the gas phase was analyzed using gas chromatography, and hydrogen, carbon oxide, and methane were identified. The influence of pH and heat treatment on the physicochemical properties of titania-based materials during photoreduction of carbon dioxide have been studied. It was found that the photocatalysts prepared in neutral environment were shown to result in a higher content of hydrogen, carbon monoxide, and methane in the gas phase compared to photocatalysts obtained under basic conditions. The highest amounts of hydrogen were detected in the processes using photocatalysts heated in the microwave reactor, and double-heated photocatalysts.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    FabianapunensisS.C.Arroyo是一种亚灌木或灌木,原产于阿根廷北部的干旱和半干旱地区,已知具有多种药用特性。本研究的目的是优化提取条件,以最大限度地获得生物活性总酚类化合物(TPC)和黄酮类化合物(F)通过使用非常规提取方法。即超声辅助提取,阿联酋,和微波辅助提取,MAE,并比较优化提取物的生物活性和毒性常规提取物,即,那些通过浸渍获得的。响应面法(RSM)用于应用析因设计来优化提取参数:固液比,提取时间,超声振幅,微波功率。最优提取条件下的TPC和F及抗氧化活性的实验值与预测值无显著差异,证明了数学模型的准确性。在常规和UAE和MAE优化的提取物之间发现了相似的HPLC-DAD模式。提取物的主要成分对应于酚类化合物(类黄酮和酚酸),并鉴定了芹菜素。所有提取物在ABTS•+上显示出高清除剂能力,O2•-和H2O2,能够抑制促炎酶黄嘌呤氧化酶(XO)和脂氧合酶(LOX)。它们还在鼠伤寒沙门氏菌测定中显示出抗突变作用和对人黑素瘤细胞的细胞毒性/抗增殖活性(SKMEL-28)。毒理学评价表明其安全性。这项工作的结果对于开发有效和可持续的方法非常重要,可持续的方法可以从Punensis获得生物活性化合物,以预防与氧化应激相关的慢性退行性疾病,炎症,和DNA损伤。
    Fabiana punensis S. C. Arroyo is a subshrub or shrub that is indigenous to the arid and semiarid region of northern Argentina and is known to possess several medicinal properties. The objective of this study was to optimize the extraction conditions so as to maximize the yield of bioactive total phenolic compound (TPC) and flavonoids (F) of F. punensis\' aerial parts by using non-conventional extraction methods, namely ultrasound-assisted extraction, UAE, and microwave-assisted extraction, MAE, and to compare the biological activities and toxicity of optimized extracts vs. conventional extracts, i.e., those gained by maceration. Response Surface Methodology (RSM) was used to apply factorial designs to optimize the parameters of extraction: solid-to-liquid ratio, extraction time, ultrasound amplitude, and microwave power. The experimental values for TPC and F and antioxidant activity under the optimal extraction conditions were not significantly different from the predicted values, demonstrating the accuracy of the mathematical models. Similar HPLC-DAD patterns were found between conventional and UAE- and MAE-optimized extracts. The main constituents of the extracts correspond to phenolic compounds (flavonoids and phenolic acids) and apigenin was identified. All extracts showed high scavenger capacity on ABTS•+, O2•- and H2O2, enabling the inhibition of the pro-inflammatory enzymes xanthine oxidase (XO) and lipoxygenase (LOX). They also showed an antimutagenic effect in Salmonella Typhimurium assay and cytotoxic/anti-proliferative activity on human melanoma cells (SKMEL-28). Toxicological evaluation indicates its safety. The results of this work are important in the development of efficient and sustainable methods for obtaining bioactive compounds from F. punensis for the prevention of chronic degenerative diseases associated with oxidative stress, inflammation, and DNA damage.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    微波热疗(MH)期间的实时准确温度监测仍然是确保治疗效果和患者安全的关键挑战。这项研究提出了一种新颖的方法来模拟真实的MH,并使用时间信息神经网络精确确定生物组织内目标区域的温度。我们对30套体模和10套离体猪肉组织进行了MH实验。我们提出了一个新的观点:对连续电磁辐射刺激的组织反应的演变是时间和空间维度的联合演变。我们的模型利用TimesNet提取周期性特征,利用Cloblock从超声图像中捕获二维周期性矢量中的全局信息相关性。通过吸收更多的超声时间数据,我们的模型提高了温度估计的准确性。在25-65°C的温度范围内,我们的神经网络对新鲜离体猪肉组织和体模实现了约0.886°C和0.419°C的温度估计均方根误差,分别。所提出的时间通知神经网络具有适度的参数计数,渲染它适合部署在超声波移动设备。此外,它达到了接近临床标准规定的温度精度,使其在生物组织MH期间的无损温度监测有效。
    Real-time and accurate temperature monitoring during microwave hyperthermia (MH) remains a critical challenge for ensuring treatment efficacy and patient safety. This study presents a novel approach to simulate real MH and precisely determine the temperature of the target region within biological tissues using a temporal-informed neural network. We conducted MH experiments on 30 sets of phantoms and 10 sets of ex vivo pork tissues. We proposed a novel perspective: the evolving tissue responses to continuous electromagnetic radiation stimulation are a joint evolution in temporal and spatial dimensions. Our model leverages TimesNet to extract periodic features and Cloblock to capture global information relevance in two-dimensional periodic vectors from ultrasound images. By assimilating more ultrasound temporal data, our model improves temperature-estimation accuracy. In the temperature range 25-65 °C, our neural network achieved temperature-estimation root mean squared errors of approximately 0.886 °C and 0.419 °C for fresh ex vivo pork tissue and phantoms, respectively. The proposed temporal-informed neural network has a modest parameter count, rendering it suitable for deployment on ultrasound mobile devices. Furthermore, it achieves temperature accuracy close to that prescribed by clinical standards, making it effective for non-destructive temperature monitoring during MH of biological tissues.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    背景:在中国,经皮微波/射频消融肝分区加门静脉栓塞术(PALPP)和经动脉化疗栓塞术(TACE)加门静脉栓塞术(PVE)均已用于计划的肝切除术.然而,缺乏关于这两种技术对未来肝脏残留(FLR)不足的病例的有效性的比较研究。
    方法:患者分为PALPP组和TACE+PVE组。临床数据,包括FLR增长率,并发症,二次切除率,和总生存率,对两组患者进行回顾性对比分析。
    结果:2014年12月至2021年10月,共有29例患者接受了TACE+PVE(n=12)和PALPP(n=17)。在TACE+PVE组中,7例患者成功行两期肝切除术,而在PALPP组中,13例患者接受了该手术(两阶段切除率:58.3%vs.76.5%,P=0.42)。一期手术的术后并发症没有显着差异(11.8%vs.8.3%,P>0.05)和二期切除并发症(0%vs.46.2%,TACE+PVE和PALPP组之间的P=0.05)。然而,PALPP组表现出第二阶段切除术的FLR体积增长时间较短(18.5天vs.66天,P=0.001)和KGR(58.5毫升/周vs.7.7毫升/周,P=0.001)。
    结论:与TACE+PVE相比,PALPP导致FLR体积的更显着增加,并且两阶段切除术的发生率更高,而不会增加术后并发症。
    BACKGROUND: In China, both percutaneous microwave/radiofrequency ablation liver partition plus portal vein embolization (PALPP) and transarterial chemoembolization (TACE) plus portal vein embolization (PVE) have been utilized in planned hepatectomy. However, there is a lack of comparative studies on the effectiveness of these two techniques for cases with insufficient future liver remnant (FLR).
    METHODS: Patients were categorized into either the PALPP group or the TACE + PVE group. Clinical data, including FLR growth rate, complications, secondary resection rate, and overall survival rate, were compared and analyzed for both groups retrospectively.
    RESULTS: Between December 2014 and October 2021, a total of 29 patients underwent TACE + PVE (n = 12) and PALPP (n = 17). In the TACE + PVE group, 7 patients successfully underwent two-stage hepatectomy, while in the PALPP group, 13 patients underwent the procedure (two-stage resection rate: 58.3% vs. 76.5%, P = 0.42). There were no significant differences in postoperative complications of one-stage procedures (11.8% vs. 8.3%, P > 0.05) and second-stage resection complication (0% vs. 46.2%, P = 0.05) between the TACE + PVE and PALPP groups. However, the PALPP group demonstrated a shorter time to FLR volume growth for second-stage resection (18.5 days vs. 66 days, P = 0.001) and KGR (58.5 ml/week vs. 7.7 ml/week, P = 0.001).
    CONCLUSIONS: Compared with TACE + PVE, PALPP results in a more significant increase in FLR volume and a higher rate of two-stage resection without increasing postoperative complications.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    尽管公众对微波辐射对健康的影响有广泛的兴趣,微波辐射对生物样品影响的研究通常是不确定的或相互矛盾的。在这里,我们研究了频率为3.5GHz的微波辐射的影响,20GHz和29GHz上微管的生长,它们是在真核细胞中执行不同功能的生物纳米管。由于微管是高度极性的,可以延伸几微米的长度,预计它们对非电离辐射敏感。此外,据推测,微管内的微管蛋白二聚体可能会在不同构象之间迅速切换,可能参与计算或其他合作过程。我们的数据表明,暴露于微波辐射会产生微管生长曲线,该曲线相对于使用均匀温度跳跃的对照研究而言是扭曲的。然而,非电离辐射的这种明显影响通过使用红外激光或热空气加热样品的对照实验来再现,从而模拟暴露于微波的样品的热历史。因此,不能确定微波辐射对微管生长的非热效应。我们的结果强调了在生物物理研究中需要进行适当的控制实验,这可能会影响公共利益的领域。
    Despite widespread public interest in the health impact of exposure to microwave radiation, studies of the influence of microwave radiation on biological samples are often inconclusive or contradictory. Here we examine the influence of microwave radiation of frequencies 3.5 GHz, 20 GHz and 29 GHz on the growth of microtubules, which are biological nanotubes that perform diverse functions in eukaryotic cells. Since microtubules are highly polar and can extend several micrometres in length, they are predicted to be sensitive to non-ionizing radiation. Moreover, it has been speculated that tubulin dimers within microtubules might rapidly toggle between different conformations, potentially participating in computational or other cooperative processes. Our data show that exposure to microwave radiation yields a microtubule growth curve that is distorted relative to control studies utilizing a homogeneous temperature jump. However, this apparent effect of non-ionizing radiation is reproduced by control experiments using an infrared laser or hot air to heat the sample and thereby mimic the thermal history of samples exposed to microwaves. As such, no non-thermal effects of microwave radiation on microtubule growth can be assigned. Our results highlight the need for appropriate control experiments in biophysical studies that may impact on the sphere of public interest.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    目的:评价热消融治疗单发低危T2N0M0甲状腺乳头状癌(PTC)的疗效和安全性,并比较微波消融(MWA)和射频消融(RFA)的疗效。
    方法:本回顾性研究,单中心研究纳入了34例患者(年龄:40.0±13.9岁;28例女性),这些患者在2016年11月至2023年4月期间患有低危T2N0M0PTC,最大直径>2cm且≤4cm,并接受了MWA(n=15)或RFA(n=19).主要结果是疾病进展的累积率和延迟手术率。相比之下,次要结果包括肿瘤大小的变化,肿瘤完全消失的累积率,和并发症发生率。
    结果:中位随访期为18.0个月(四分位距[IQR]:9.0-40.0个月)。12个月时,消融区容积减少率中位数为74.2%(IQR:53.7%-86.0%).在1年内有两名患者出现疾病进展,包括一名RFA后局部肿瘤进展的患者和一名MWA后新肿瘤的患者,导致整个剩余随访期间的累积疾病进展率为8.8%(95%置信区间[CI]:0%-19.8%).两名患者随后接受了额外的消融治疗,不需要手术。1年、3年和5年肿瘤完全消失的累积率为4.0%(95%CI:0%-11.4%),26.8%(95%CI:2.7%-44.9%),和51.2%(95%CI:0%-79.1%),分别。MWA和RFA组之间的疾病进展率(P=0.829)或肿瘤完全消失率(P=0.633)没有显着差异。出现短暂性声音嘶哑的患者占14.7%(5/34)。RFA的并发症发生率高于MWA,但无统计学意义(21.1%[4/19]vs.6.7%[1/15];P=0.355)。
    结论:MWA和RFA在治疗单发低危T2N0M0PTC的疗效和安全性方面均显示出有希望的短期结果,没有显著差异。
    OBJECTIVE: To evaluate the efficacy and safety of thermal ablation in treating solitary low-risk T2N0M0 papillary thyroid cancer (PTC) and compare the outcomes of microwave ablation (MWA) and radiofrequency ablation (RFA).
    METHODS: This retrospective, single center study involved 34 patients (age: 40.0 ± 13.9 years; 28 female) who had low-risk T2N0M0 PTC with a maximum diameter >2 cm and ≤4 cm and underwent MWA (n = 15) or RFA (n = 19) from November 2016 to April 2023. The primary outcomes were the cumulative rate of disease progression and delayed surgery rates. In contrast, the secondary outcomes included changes in tumor size, cumulative rate of complete tumor disappearance, and complication rates.
    RESULTS: The median follow-up period was 18.0 months (interquartile range [IQR]: 9.0-40.0 months). At 12 months, the median volume reduction rate of the ablation zone was 74.2% (IQR: 53.7%-86.0%). Disease progression was noted in two patients within 1 year, including one patient with local tumor progression post-RFA and one with a new tumor post-MWA, resulting in a constant cumulative disease progression rate of 8.8% (95% confidence interval [CI]: 0%-19.8%) throughout the remaining follow-up period. Both patients were subsequently treated with additional ablation and did not require surgery. The cumulative rates of complete tumor disappearance at 1, 3, and 5 years were 4.0% (95% CI: 0%-11.4%), 26.8% (95% CI: 2.7%-44.9%), and 51.2% (95% CI: 0%-79.1%), respectively. No significant differences were observed in the disease progression (P = 0.829) or complete tumor disappearance (P = 0.633) rates between the MWA and RFA groups. Complications occurred in 14.7% (5/34) of patients presenting with transient hoarseness. RFA had a higher but not statistically significant complication rate than MWA did (21.1% [4/19] vs. 6.7% [1/15]; P = 0.355).
    CONCLUSIONS: Both MWA and RFA demonstrated promising short-term outcomes in terms of efficacy and safety in treating solitary low-risk T2N0M0 PTC, with no significant differences.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    微波可以安全和无损地照亮和穿透电介质材料,使它们成为各种医疗任务的有吸引力的解决方案,包括检测,诊断,分类,和监测。它们固有的电磁特性,便携性,成本效益,计算能力的增长促进了医疗领域众多微波传感和成像系统的发展,有可能补充甚至取代当前的黄金标准方法。这篇综述旨在全面更新微波医疗应用的最新进展,特别关注在1-15GHz频率范围内工作的近场。它特别检查了脑中风诊断和分类临床设备开发的重大进展,乳腺癌筛查,和连续血糖监测。详细讨论了原型和设备的技术实现和算法方面,包括收发器系统,辐射元件(如天线和传感器),和成像算法。此外,它概述了其他有前途的尖端微波医疗应用,如膝关节损伤和结肠息肉检测,躯干扫描和基于图像的热疗干预监测。最后,这篇综述讨论了利用微波技术实现临床参与的挑战,并探讨了未来的前景。
    Microwaves can safely and non-destructively illuminate and penetrate dielectric materials, making them an attractive solution for various medical tasks, including detection, diagnosis, classification, and monitoring. Their inherent electromagnetic properties, portability, cost-effectiveness, and the growth in computing capabilities have encouraged the development of numerous microwave sensing and imaging systems in the medical field, with the potential to complement or even replace current gold-standard methods. This review aims to provide a comprehensive update on the latest advances in medical applications of microwaves, particularly focusing on the near-field ones working within the 1-15 GHz frequency range. It specifically examines significant strides in the development of clinical devices for brain stroke diagnosis and classification, breast cancer screening, and continuous blood glucose monitoring. The technical implementation and algorithmic aspects of prototypes and devices are discussed in detail, including the transceiver systems, radiating elements (such as antennas and sensors), and the imaging algorithms. Additionally, it provides an overview of other promising cutting-edge microwave medical applications, such as knee injuries and colon polyps detection, torso scanning and image-based monitoring of thermal therapy intervention. Finally, the review discusses the challenges of achieving clinical engagement with microwave-based technologies and explores future perspectives.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    由于其无标记和非侵入性,细胞介电特性测量在细胞检测和诊断中具有重要的应用潜力。在这项研究中,我们开发了一种生物传感器,用于测量液体样品的介电常数,特别是纳升尺度的细胞悬浮液,利用微波和毫米波共面波导结合微通道。该生物传感器有助于在1GHz至110GHz的频域内测量散射参数。然后使用特定算法将获得的散射参数转换为介电常数。微通道内的细胞捕获结构确保细胞悬浮液在测量区内保持稳定。通过与商业Keysight探针比较,证实了该生物传感器的可行性。我们使用我们的生物传感器测量了三种不同细胞悬浮液(HepG2,A549,MCF-7)的介电常数。我们还计算了每种细胞类型在多次测量中捕获的细胞数量,并比较了相应的介电常数变化。结果表明,HepG2细胞的介电常数的实部比其他两种细胞类型的介电常数低0.2-0.8。A549和MCF-7之间的差异相对较小,只有0.2-0.4。测量过程中细胞数量变化引起的介电谱波动小于不同细胞类型之间观察到的差异。因此,该传感器适用于测量细胞悬浮液,可用于无标签,鉴定生物细胞悬液的非侵入性研究。
    Cell dielectric property measurement holds significant potential for application in cell detection and diagnosis due to its label-free and noninvasive nature. In this study, we developed a biosensor designed to measure the permittivity of liquid samples, particularly cell suspensions at the nanoliter scale, utilizing microwave and millimeter wave coplanar waveguides in conjunction with a microchannel. This biosensor facilitates the measurement of scattering parameters within a frequency domain ranging from 1 GHz to 110 GHz. The obtained scattering parameters are then converted into dielectric constants using specific algorithms. A cell capture structure within the microchannel ensures that cell suspensions remain stable within the measurement zone. The feasibility of this biosensor was confirmed by comparison with a commercial Keysight probe. We measured the dielectric constants of three different cell suspensions (HepG2, A549, MCF-7) using our biosensor. We also counted the number of cells captured in multiple measurements for each cell type and compared the corresponding changes in permittivity. The results indicated that the real part of the permittivity of HepG2 cells is 0.2-0.8 lower than that of the other two cell types. The difference between A549 and MCF-7 was relatively minor, only 0.2-0.4. The fluctuations in the dielectric spectrum caused by changes in cell numbers during measurements were smaller than the differences observed between different cell types. Thus, the sensor is suitable for measuring cell suspensions and can be utilized for label-free, noninvasive studies in identifying biological cell suspensions.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    Heck反应被广泛用于构建各种生物相关支架,并已成功用于生产活性药物成分(API)。通常,与末端烯烃的反应对反式取代的烯烃产物具有较高的产率和立体选择性,和原始协议的许多绿色变体已被开发用于此类底物。然而,这些方法可能无法以相同的效率应用于具有挑战性底物的反应,如内烯烃,提供三取代的烯烃。在目前的工作中,我们在绿色条件下实施了Heck反应方案,以获得三取代的烯烃作为最终产物或具有药物意义的关键中间体。对模型反应进行的一组初步实验导致基于实验设计(DoE)研究选择简单且绿色的设置。以这样的方式,最佳实验条件(催化剂负载量,烯烃的等价物,碱和四烷基铵盐,composition,和溶剂的量)已经确定。然后,进行了第二组实验,使反应完成并考虑其他因素。如此定义的方案涉及使用EtOH作为溶剂,微波(MW)辐射以实现短反应时间,和负载型催化剂PdEnCat®40,它提供了更容易的回收和再利用。在不同的芳基溴化物和内部烯烃上测试这些条件以评估底物范围。此外,为了尽可能限制废物的产生,开发了一种简单的异构化程序,将异构副产物转化为所需的共轭烯烃,这也是热力学上最受欢迎的产品。本文公开的方法代表绿色,高效,和易于使用的处理对不同的三取代的烯烃通过Heck反应。
    The Heck reaction is widely employed to build a variety of biologically relevant scaffolds and has been successfully implemented in the production of active pharmaceutical ingredients (APIs). Typically, the reaction with terminal alkenes gives high yields and stereoselectivity toward the trans-substituted alkenes product, and many green variants of the original protocol have been developed for such substrates. However, these methodologies may not be applied with the same efficiency to reactions with challenging substrates, such as internal olefins, providing trisubstituted alkenes. In the present work, we have implemented a Heck reaction protocol under green conditions to access trisubstituted alkenes as final products or key intermediates of pharmaceutical interest. A set of preliminary experiments performed on a model reaction led to selecting a simple and green setup based on a design of experiments (DoE) study. In such a way, the best experimental conditions (catalyst loading, equivalents of alkene, base and tetraalkylammonium salt, composition, and amount of solvent) have been identified. Then, a second set of experiments were performed, bringing the reaction to completion and considering additional factors. The protocol thus defined involves using EtOH as the solvent, microwave (mw) irradiation to achieve short reaction times, and the supported catalyst Pd EnCat®40, which affords an easier recovery and reuse. These conditions were tested on different aryl bromides and internal olefines to evaluate the substrate scope. Furthermore, with the aim to limit as much as possible the production of waste, a simple isomerization procedure was developed to convert the isomeric byproducts into the desired conjugated E alkene, which is also the thermodynamically favoured product. The approach herein disclosed represents a green, efficient, and easy-to-use handle towards different trisubstituted alkenes via the Heck reaction.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

公众号