Tetrahedron最新文献

英文中文

Sustainable aqueous-mediated one-pot synthesis of 2-hydroxy-5-oxo-5,6,7,8-tetrahydro-4H-chromene and coumarin derivatives using taurine as the green bioorganic catalyst 以牛磺酸为绿色生物有机催化剂，在水介导下可持续地一步合成 2-羟基-5-氧代-5,6,7,8-四氢-4H-色烯和香豆素衍生物

IF 2.1 3区化学 Q2 CHEMISTRY, ORGANIC

Tetrahedron

Pub Date : 2024-10-28 DOI: 10.1016/j.tet.2024.134346

Kamlesh Saini, Ashok K. Raigar, Manju, Nirmal Jyoti, Anjali Guleria

In this study, two taurine-catalyzed, aqueous-mediated methodologies were reported for the synthesis of 4-aryl-2-hydroxy-7,7-dimethyl-5,6,7,8-tetrahydro-4H-chromen-5-one (3a-j) and 3-substituted coumarin derivatives (3′a-f) under reflux conditions. These methodologies entail the use of substituted aromatic aldehydes, diethyl malonate, and dimedone as reagents for the sustainable synthesis of 2-hydroxy-tetrahydro-4H-chromene derivatives via the Knoevenagel-Michael cascade, as well as the use of substituted salicylaldehyde with diethyl malonate or ethyl 3-oxobutanoate for the efficient synthesis of coumarin derivatives via the Knoevenagel-transesterification reaction. These strategies emphasize environmental sustainability and are designed as one-pot processes, ensuring simplicity and convenience. The methods deliver high yields and are cost-effective, significantly reducing reaction times, enhancing step efficiency, and are successful at the multigram level. Notably, the taurine catalyst demonstrates exceptional reusability, maintaining its activity for up to five cycles without notable degradation. The catalyst is easily recoverable through filtration, and the overall procedure is streamlined, requiring no additional purification steps. These attributes collectively contribute to the green chemistry paradigm by minimizing waste and energy consumption, thus offering a practical and efficient approach to the synthesis of these important organic compounds.

本研究报告了在回流条件下合成 4-芳基-2-羟基-7,7-二甲基-5,6,7,8-四氢-4H-苯并吡喃-5-酮 (3a-j) 和 3-取代香豆素衍生物 (3′a-f) 的两种牛磺酸催化的水介导方法。这些方法包括使用取代的芳香醛、丙二酸二乙酯和二甲基酮作为试剂，通过克诺文那格尔-迈克尔级联反应可持续合成 2-羟基-四氢-4H-苯并吡喃衍生物；以及使用取代的水杨醛与丙二酸二乙酯或 3-氧代丁酸乙酯，通过克诺文那格尔-酯化反应高效合成香豆素衍生物。这些策略强调环境的可持续性，并设计为单锅工艺，确保简单方便。这些方法产率高，成本效益高，大大缩短了反应时间，提高了步骤效率，并在多克水平上取得了成功。值得注意的是，牛磺酸催化剂具有卓越的可重复使用性，其活性可维持长达五个循环，且无明显降解。通过过滤，催化剂很容易回收，而且整个程序简化，不需要额外的纯化步骤。这些特性共同促进了绿色化学的发展，最大限度地减少了废物和能源消耗，从而为合成这些重要的有机化合物提供了一种实用、高效的方法。

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引用次数: 0

Multicomponent synthesis of 7-(diethylamino)coumarin–pyrrolo[3,4-b]pyridin-5-one conjugates and modulation of their twisted intramolecular charge transfer (TICT) processes 7-(二乙基氨基)香豆素-吡咯并[3,4-b]吡啶-5-酮共轭物的多组分合成及其扭曲分子内电荷转移（TICT）过程的调制

IF 2.1 3区化学 Q2 CHEMISTRY, ORGANIC

Tetrahedron

Pub Date : 2024-10-28 DOI: 10.1016/j.tet.2024.134335

Julio C. Flores-Reyes , Alejandro Valderrama-Celestino , María F. Trejo-Velasco , Karla I. Jaramillo-Márquez , Federico González , Alberto Rojas-Hernández , Annia Galano , Alejandro Islas-Jácome , Eduardo González-Zamora

By coupling an Ugi-Zhu three-component reaction to a cascade sequence (aza Diels-Alder cycloaddition/N-acylation/decarboxylation/dehydration) into a one-pot process, seven new 7-(diethylamino)coumarin-pyrrolo[3,4-b]pyridin-5-one bis-heterocyclic conjugates were synthesized in moderate overall yields (15–38 %). Next, the photophysical properties of all products were determined using UV–Vis and fluorescence spectroscopy. These products exhibited fluorescence quantum yields (FQY) ranging from 17 % to 25 %. In contrast, one of their precursors, the free 7-(diethylamino)-3-carbaldehyde displayed a low FQY of 2 %, and, also exhibited dual emission across all solvents used for the measurements. The increase in quantum yield observed upon incorporation of the coumarin moiety into MCR products was attributed to the inhibition of the twisted intramolecular charge transfer (TICT) process. This one naturally occurs in the free coumarin but was suppressed in the products due to a decrease in the acceptor strength of the substituent at position 3 of the coumarin moiety. Furthermore, the electronic structure of the compounds was computed by DFT/TD-DFT calculations allowing to determine which molecular orbitals (MO) were involved in the electronic transitions.

通过将 Ugi-Zhu 三组分反应与级联顺序（氮杂 Diels-Alder 环加成/N-酰化/脱羧/脱水）耦合为一锅工艺，合成了七种新的 7-(二乙基氨基)香豆素-吡咯并[3,4-b]吡啶-5-酮双环共轭物，总产率适中（15-38%）。接下来，使用紫外可见光谱和荧光光谱测定了所有产物的光物理特性。这些产物的荧光量子产率（FQY）在 17% 到 25% 之间。相比之下，它们的前体之一，游离的 7-（二乙基氨基）-3-甲醛的荧光量子产率较低，仅为 2%，而且在测量所用的所有溶剂中都表现出双重发射。在 MCR 产物中加入香豆素分子后，量子产率有所提高，这是因为分子内电荷转移（TICT）过程受到抑制。这一过程在游离香豆素中自然发生，但由于香豆素分子第 3 位取代基的受体强度降低，在产物中受到抑制。此外，还通过 DFT/TD-DFT 计算确定了化合物的电子结构，从而确定了哪些分子轨道（MO）参与了电子跃迁。

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引用次数: 0

Advancements in the selective transformation of olefins to new C–C bonds through cooperative catalysis involving electrochemistry and transition metals 通过电化学和过渡金属的协同催化，推进烯烃向新 C-C 键的选择性转化

IF 2.1 3区化学 Q2 CHEMISTRY, ORGANIC

Tetrahedron

Pub Date : 2024-10-28 DOI: 10.1016/j.tet.2024.134330

ChunXiao Nong, Yi Jin

This article aims to comprehensively review the research progress in the selective C–C bond formation of olefins through the synergistic action of electrochemistry and transition metal catalysis in recent years, particularly since 2018. Specifically, we will focus on how the combined catalysis of electrochemistry and transition metals achieves precise control over chemical, stereoselective, and regioselective outcomes, and delve deeply into the underlying reaction mechanisms. By summarizing key scientific discoveries and technological breakthroughs, this article aims to provide a reference guide for researchers in related fields and offer insights into future trends and potential applications in this domain.

本文旨在全面回顾近年来，尤其是2018年以来，通过电化学和过渡金属催化协同作用选择性形成烯烃C-C键的研究进展。具体而言，我们将重点关注电化学和过渡金属的联合催化如何实现对化学、立体选择性和区域选择性结果的精确控制，并深入探讨其背后的反应机理。通过总结关键科学发现和技术突破，本文旨在为相关领域的研究人员提供参考指南，并为该领域的未来趋势和潜在应用提供见解。

引用次数: 0

Synthesis and applications of optically pure trans-2-(3,5-dimethylphenoxy)cyclohexan-1-ol as chiral auxiliary for preparation of α-substituted carboxylic acid derivatives 光学纯反式-2-(3,5-二甲基苯氧基)环己-1-醇作为制备α-取代羧酸衍生物的手性助剂的合成与应用

IF 2.1 3区化学 Q2 CHEMISTRY, ORGANIC

Tetrahedron

Pub Date : 2024-10-28 DOI: 10.1016/j.tet.2024.134326

Atul R. Pandavadara, Aditya N. Khanvilkar, Ashutosh V. Bedekar

In the present work, trans-2-(3,5-dimethylphenoxy)cyclohexan-1-ol was synthesized and its enantiomers were separated by Enzymatic Kinetic Resolution (EKR). The absolute configuration was established by converting to diastereomer with esters of known chiral description. Chiral alcohol was then used as an auxiliary for the preparation of esters by coupling with racemic α-halo acids in presence of DCC and a suitable base. We observed an efficient Dynamic Kinetic Resolution as the product esters were obtained in enriched diastereomeric forms. Effect of several parameters like base, temperature and reaction time was studied. The relative energy profile of the diastereomers was studied by computational analysis and the energy difference of diastereomeric products were in accordance with the observed diastereoselectivity. The chirally pure α-halo acid could be separated from the auxiliary, without any loss of optical purity of both components.

本研究合成了反式-2-(3,5-二甲基苯氧基)环己-1-醇，并通过酶促动力学解析（EKR）分离了其对映体。通过使用已知手性描述的酯转化成非对映异构体，确定了绝对构型。然后用手性醇作为辅助剂，在 DCC 和适当的碱存在下，通过与外消旋α-卤酸偶联制备酯。我们观察到一种高效的动态动力学解析，因为产物酯是以非对映形式富集得到的。我们研究了碱、温度和反应时间等参数的影响。通过计算分析研究了非对映异构体的相对能量曲线，非对映产物的能量差与观察到的非对映选择性相符。手性纯的α-卤酸可以从助剂中分离出来，而不会损失两种成分的光学纯度。

引用次数: 0

A short approach to cytogenin and first total synthesis of aspergisocoumarin A and fusarimarin C 细胞苷元的简易合成方法以及曲霉香豆素 A 和 fusarimarin C 的首次全合成

IF 2.1 3区化学 Q2 CHEMISTRY, ORGANIC

Tetrahedron

Pub Date : 2024-10-26 DOI: 10.1016/j.tet.2024.134343

Goreti Rajendar, Mintu Rehman

A novel, efficient route to the first total synthesis of the bioactive isocoumarins aspergisocoumarin A, fusarimarin C and cytogenin is demonstrated. This approach features a groundbreaking single-step synthesis of isocoumarins utilizing a challenging cross-ester coupling of ethyl dimethoxy orsellinate and ethyl glycolate in the presence of a LiBr-LiTMP complex. The process leverages bromide ion-induced aggregation to facilitate a one-pot tandem reaction sequence: lateral lithiation, acylation, enolization, and lactonization. This innovative method directly produces the isocoumarin moiety with high efficiency. Subsequent transformations include selective BBr₃-mediated demethylation, oxidation, and Wittig reactions. The streamlined synthetic routes demonstrated: a two-step pathway to cytogenin and a four-step sequence to aspergisocoumarin A and fusarimarin C, achieving overall yields of 37 %, 27 %, and 27 % respectively.

本研究展示了首次全合成具有生物活性的异香豆素天仙子香豆素 A、扶桑香豆素 C 和细胞苷元的新颖、高效路线。这种方法的特点是，在 LiBr-LiTMP 复合物存在的情况下，利用二甲氧基丁二酸乙酯和乙醇酸乙酯的高难度交叉酯偶联，开创性地一步合成异香豆素。该工艺利用溴离子诱导的聚合作用来促进单锅串联反应序列：侧向石碳酸化、酰化、烯醇化和内酯化。这种创新方法能高效地直接生成异香豆素分子。随后的转化过程包括选择性 BBr3 介导的去甲基化、氧化和 Wittig 反应。所展示的简化合成路线包括：两步合成细胞苷元，四步合成曲霉香豆素 A 和扶桑香豆素 C，总产率分别为 37%、27% 和 27%。

引用次数: 0

A classical peptide coupling approach for the total synthesis of simnotrelvir 用于全合成 simnotrelvir 的经典肽偶联方法

IF 2.1 3区化学 Q2 CHEMISTRY, ORGANIC

Tetrahedron

Pub Date : 2024-10-26 DOI: 10.1016/j.tet.2024.134342

Siva Ramakrishna Paipuri , Srihari Pabbaraja

The total synthesis of an oral small-molecule antiviral agent; a structure based developmental drug simnotrelvir has been accomplished. The synthesis involves readily accessible commercial amino acids L-tert-leucine, 4-hydroxy-l-proline and l-glutamic acid that are easily converted to the key intermediates and are coupled together following classical peptide coupling technique using HATU and NMM. One of the crucial step in the synthesis involved a one pot Boc-deprotection and trifluoroacetylation of tert-leucine amino acid moiety mediated by ZnCl₂.

我们完成了口服小分子抗病毒剂的全合成；这是一种基于结构的开发药物 simnotrelvir。该合成涉及容易获得的商用氨基酸 L-叔亮氨酸、4-羟基-l-脯氨酸和 l-谷氨酸，它们很容易转化为关键的中间体，并通过使用 HATU 和 NMM 的经典肽偶联技术偶联在一起。合成过程中的一个关键步骤是在 ZnCl2 的介导下对叔亮氨酸氨基酸分子进行 Boc-脱保护和三氟乙酰化反应。

引用次数: 0

Facile synthesis of spiro-heterocycles through one-pot multicomponent [3 + 3] cross 1,3-dipolar cycloaddition reactions 通过单锅多组分[3 + 3]交叉 1,3-二极环加成反应轻松合成螺环杂环

IF 2.1 3区化学 Q2 CHEMISTRY, ORGANIC

Tetrahedron

Pub Date : 2024-10-26 DOI: 10.1016/j.tet.2024.134328

Guo-Yang Ma , Ya-Fei Li , Qing Xu , Yue-Yao Ma , Ya-Wen Li , Guo-Qiang Gong , Ning Zhang , Tan Dang , Kai-Kai Wang

A three-component 1,3-dipolar cycloaddition reaction involving ninhydrin, proline, and nitrile imines, which are generated in situ from hydrazonoyl chlorides, has been developed. This transformation can be conceptualized as a cross-1,3-dipolar cycloaddition reaction between two distinct ylides, proceeding via a [3 + 3] annulation pathway. This approach offers a swift route to a diverse array of novel and structurally intricate spiro-multiheterocyclic skeletons, achieving good yields ranging from 80 % to 94 %. Furthermore, the chemical structure of a representative product has been rigorously confirmed via X-ray diffraction analysis.

我们开发了一种涉及茚三酮、脯氨酸和腈亚胺的三组分 1,3-二极环加成反应，腈亚胺是由肼酰氯原位生成的。这种转化可以概念化为两种不同酰化物之间的交叉-1,3-双极环加成反应，通过[3 + 3]环化途径进行。这种方法提供了一条通向一系列结构复杂的新型螺多杂环骨架的捷径，可获得 80% 至 94% 的良好产率。此外，一种代表性产品的化学结构已通过 X 射线衍射分析得到严格确认。

引用次数: 0

PPh3 promoted stereospecific synthesis of ethyl α-chloroacrylates from ethyl trichloroacetate and arylaldehydes PPh3 促进以三氯乙酸乙酯和芳基醛为原料立体特异性合成 α-氯丙烯酸乙酯

IF 2.1 3区化学 Q2 CHEMISTRY, ORGANIC

Tetrahedron

Pub Date : 2024-10-26 DOI: 10.1016/j.tet.2024.134341

Axel Pliego-Santillan , Ulises J. Vargas-Cruz , Salvador Mastachi-Loza , Misael A. Romero-Reyes , Diego Martínez-Otero , Moisés Romero-Ortega

A coupling reaction between arylaldehydes and ethyl trichloroacetate is facilitated by PPh₃ under mild conditions to stereospecifically produce (Z)-ethyl α-chloroacrylates. This stereospecific coupling reaction only occurs when the arylaldehyde derivative has an electron-withdrawing substituent. On the other hand, when an electron-donating group is present in the aromatic ring, the aryldichloromethyl derivative is formed as the only product, even at low temperature. The stereospecificity in the coupling reaction was established based on the coupling constants ²J_CH and ³J_CH in the ¹³C NMR and crystal-X-ray analysis. From this data we propose that the formation of these compounds occurs through two intermediates initially formed by the reaction between the PPh₃ and ethyl trichloroacetate.

在温和的条件下，PPh3 可促进芳基醛与三氯乙酸乙酯之间的偶联反应，从而立体定向地生成 (Z)- α-氯丙烯酸乙酯。这种立体特异性偶联反应只有在芳基醛衍生物具有抽电子取代基时才会发生。另一方面，当芳香环中存在一个电子奉献基团时，即使在低温条件下，芳基二氯甲基衍生物也是唯一的产物。根据 13C NMR 和晶体-X 射线分析中的耦合常数 2JCH 和 3JCH，确定了耦合反应的立体特异性。根据这些数据，我们认为这些化合物是通过 PPh3 和三氯乙酸乙酯反应最初形成的两个中间体形成的。

引用次数: 0

Tuning the photophysical and NLO properties of β-diketonates derived from coumarin-triphenylamine-chalcones: Effect of the BF2 group 调谐香豆素-三苯胺-查耳酮衍生的 β-二酮酸酯的光物理和 NLO 特性：BF2 基团的影响

IF 2.1 3区化学 Q2 CHEMISTRY, ORGANIC

Tetrahedron

Pub Date : 2024-10-26 DOI: 10.1016/j.tet.2024.134338

Edgard Fabián Blanco-Acuña , Iván Alessandro Texon-García , Luis Antonio Vázquez-López , Alfredo Pérez-Gamboa , Héctor García-Ortega

Herein the synthesis of three difluoroboron β-diketonate complexes (7a-c) and one chalcone (7d) with coumarin and triphenylamine fragments is described. The effect of the inclusion of the difluoroboron (BF₂) group and a phenyl linker on the photophysical properties, intramolecular charge transfer (ICT) and nonlinear optical (NLO) properties was studied. These dyes exhibited excellent ICT properties due to their A-π-D and D-π-A-π-D type push-pull configuration. Thus, all compounds presented a strong solvatochromism, given the absorption and emission maxima shifted to red because of the increase in the polarity of the medium. In addition to this, 7a-d showed the formation of a twisted intramolecular charge transfer (TICT) state, which quenched fluorescence in polar solvents. Compounds 7a, 7b and 7d exhibited aggregation-induced emission (AIE) in MeCN/H₂O mixtures, while 7c did not have this behavior. In addition, all compounds showed emission in the solid state. Using DFT and TD-DFT calculations, the molecular geometries of the ground state S₀ and the first excited state S₁ were elucidated, which confirmed the formation of a TICT state. Furthermore, the theoretical and experimental absorption electronic transitions were correlated by testing different functionals: B3LYP, CAM-B3LYP, PBE0, wB97XD, HSEH1PBE and M062X. Frontier molecular orbitals (FOMs) and molecular electrostatic potentials (MEPs) supported the ICT from the donor to the acceptor group. The global reactivity descriptors were studied and the NLO properties were predicted by calculating first (β_tot) and second-order (γ_ave) hyperpolarizabilities, revealing that 7a-d would present promising NLO behavior.

本文介绍了三种二氟硼β-二酮配合物（7a-c）和一种含有香豆素和三苯胺片段的查尔酮（7d）的合成。研究了加入二氟硼（BF2）基团和苯基连接剂对光物理特性、分子内电荷转移（ICT）和非线性光学（NLO）特性的影响。由于这些染料具有 A-π-D 和 D-π-A-π-D 型推拉构型，因此表现出优异的 ICT 特性。因此，由于介质极性的增加，吸收和发射的最大值向红色移动，所有化合物都呈现出强烈的溶解变色现象。此外，7a-d 还形成了分子内电荷转移（TICT）扭曲态，在极性溶剂中淬灭了荧光。化合物 7a、7b 和 7d 在 MeCN/H2O 混合物中显示出聚集诱导发射（AIE），而 7c 则没有这种行为。此外，所有化合物在固态下都显示出发射。通过 DFT 和 TD-DFT 计算，阐明了基态 S0 和第一激发态 S1 的分子几何结构，证实了 TICT 态的形成。此外，通过测试不同的函数，对理论和实验吸收电子跃迁进行了相关分析：B3LYP、CAM-B3LYP、PBE0、wB97XD、HSEH1PBE 和 M062X。前沿分子轨道（FOMs）和分子静电位（MEPs）支持从供体基团到受体基团的信息和通信技术。通过计算一阶（βtot）和二阶（γave）超极化率，研究了全局反应性描述符并预测了 NLO 特性，结果表明 7a-d 具有良好的 NLO 行为。

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DFT calculations of properties of CF3-carbocations of the thiophene series as key intermediates in the synthesis of novel CF3-thiophenes 噻吩系列 CF3-配位物作为合成新型 CF3-噻吩的关键中间体的性质的 DFT 计算

IF 2.1 3区化学 Q2 CHEMISTRY, ORGANIC

Tetrahedron

Pub Date : 2024-10-25 DOI: 10.1016/j.tet.2024.134321

Olesya V. Khoroshilova , Irina A. Boyarskaya , Aleksander V. Vasilyev

Trimethylsilyl ethers of thiophen-2-yl-(trifluoromethyl)methanols undergo multichannel electrophilic transformations under the action of Brønsted superacid acid CF₃SO₃H to form a wide range of CF₃-substituted thiophene structures. The key cationic intermediates of these transformations are CF₃-carbocations. Electronic and orbital characteristics, global electrophilicity indices, and thermodynamic characteristics of these key intermediates have been calculated with a use of the density functional theory (DFT). Experimental data on the reactivity of intermediate cationic species have been explained on the basis of the results of quantum chemical calculations. It has been shown that reactions of the cations with aromatic nucleophiles are mainly ruled by orbital control.

噻吩-2-基-(三氟甲基)甲醇的三甲基硅醚在布氏超酸性酸 CF3SO3H 的作用下发生多通道亲电转化，形成多种 CF3 取代的噻吩结构。这些转化的关键阳离子中间体是 CF3-配位体。利用密度泛函理论（DFT）计算了这些关键中间产物的电子和轨道特征、全局亲电指数以及热力学特征。量子化学计算的结果解释了中间阳离子物种反应性的实验数据。结果表明，阳离子与芳香族亲核物的反应主要受轨道控制。

引用次数: 0

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