基于分子钳化合物的手性识别研究进展

手性是自然界中广泛存在的现象,设计合成新型人工受体模拟生物体内的分子识别已经成为生物有机化学和超分子化学等领域富于挑战性的课题之一.分子钳类人工受体结构易于修饰,在手性识别和检测中具有广泛的应用前景,本文对近年来合成的分子钳人工受体以及应用光谱、色谱和质谱等检测手段对其手性识别性能的研究进行了总结,并对分子钳人工受体的发展前景作出了展望.     

微波促进无溶剂条件下酯键型猪去氧胆酸分子钳的快速有效合成

在微波辐射无溶剂条件下, 以固体K2CO3为载体, 猪去氧胆酸甲酯与芳酰氯反应合成了11个猪去氧胆酸分子钳人工受体. 所有化合物的结构均经1H NMR, IR, MS及元素分析所确证. 同传统方法相比, 该法具有简单、快速、 有效、 对环境友好等优点. 同时考察了这类受体对芳胺和手性分子的识别性能. 结果表明, 这类分子钳受体不但对芳胺具有优良的识别性能, 而且对D/L-氨基酸甲酯具有对映选择性识别性能.     

新的手性芳酰胺分子钳的微波干法合成

在微波辐射无溶剂条件下, 以1,3-二苯氧乙酸为隔离基, L-氨基酸甲酯为手臂设计合成了9个新的分子钳人工受体. 所有化合物的结构均经1H NMR, IR, MS及元素分析所确证. 同传统方法相比, 该法具有简单、快速、有效、对环境友好等优点. 初步的实验结果表明, 这类分子钳受体对D/L-氨基酸甲酯具有良好的对映选择性识别性能.     

新的芳酰肼分子钳人工受体的微波干法合成及其识别性能研究

在微波辐射无溶剂条件下,以间苯二酚为起始原料,固体K2CO3为载体,设计合成了9个新的芳杂环酰肼分子钳人工受体.其结构均经1HNMR,IR,MS及元素分析确证.同传统的方法相比,该法具有简单、快速、高效和对环境友好等优点.利用紫外可见分光光度滴定法初步考察了这类分子钳对卤素阴离子的识别性能.结果表明,该类分子钳对I-具有良好的选择性识别性能.     

分子钳人工受体研究进展

分子识别是生物体系的基本特征, 并在生命活动中起中心作用. 利用合成的人工受体与适当底物间的分子识别以建立化学模型或化学仿生体系对生命过程中的分子识别现象进行模拟研究是生物有机化学和超分子化学前沿富于挑战的课题之一. 按照不同的隔离基, 综述了分子钳人工受体的研究进展.     

芳杂环类多重氢键分子钳人工受体研究新进展

氢键是分子识别的重要推动力之一.综述了芳杂环类多重氢键分子钳人工受体研究进展.     

微波合成氨基甲酸酯型脱氧胆酸分子钳及其分子识别性能

用脱氧胆酸甲酯和三光气为原料,微波辐射作用下在脱氧胆酸甲酯3位反应生成酰氯后,继续在微波辐射作用下与各种芳胺反应,合成了10个新的氨基甲酸酯型脱氧胆酸分子钳人工受体,产率79~95%,其结构经质谱、红外、核磁和元素分析表征。用UV-Vis方法初步研究了分子钳4a~4j对客体中性分子的识别性能。结果表明,分子钳4a~4j对所考察的中性分子显示良好的识别作用,分子钳与中性分子间形成1∶1型主客体络合物,除分子钳4c外,识别顺序皆为:苯胺邻甲氧苯胺间甲氧苯胺对甲氧苯胺。     

脱氧胆酸手性分子钳的微波合成及其对中性分子的识别性能研究

在微波辐射条件下,以脱氧胆酸甲酯为间隔基,高产率合成了5个脱氧胆酸手性分子钳人工受体,其结构经IR,1HNMR,MS及元素分析确证。用差紫外光谱法测定了其对中性分子的识别性能。实验结果表明,这类分子钳人工受体对所考察的客体分子有良好的识别作用,主客体间形成1∶1型主客体配合物,受体5d对苯胺的结合常数高达14171.39 M-1。     

新型脱氧胆酸类手性不对称脲分子钳的设计合成

以刚性的脱氧胆酸甲酯为隔离基, 在其3位连接苯甲酰基, 12位连接手性不对称脲, 设计合成了一类新型的手性分子钳. 其结构均经1H NMR, IR, MS和元素分析确证, 并且考察了其对中性分子和D/L-氨基酸甲酯的识别性能. 实验结果表明, 这类分子钳人工受体不仅对中性有机小分子具有良好的识别能力, 而且对D/L-氨基酸甲酯亦具有优良的对映选择性识别性能.     

氨基甲酸酯型石胆酸分子裂缝的微波合成

利用人工受体与适当底物间的分子识别以建立仿生模型的研究已成为生物有机化学的前沿领域之一。作为一类新型的人工受体,分子裂缝近年来在分子识别、生物传感、外消旋体的拆分、分子器件等领域引起越来越多的关注[1-3]。胆甾因其具有刚性的凹面结构和固有的手性,是构筑钳形人工     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.