不含手性碳的手性化合物及其绝对构型——剑桥结构数据库实例分析

利用英国剑桥结构数据库中的实例并结合相关三维可视化软件,介绍了含有氮/磷等手性杂原子、轴手性、平面手性、螺旋手性、超分子手性等手性因素的手性化合物及其绝对构型,以加深对手性概念的认识和理解。     

手性溶剂诱导非手性物质手性的研究进展

手性溶剂诱导非手性物质产生手性是目前合成手性物质的主流方法之一。与传统的手性物质合成方法相比,手性溶剂诱导法不仅避免了使用昂贵的手性试剂,还能扩大合成手性物质的结构范围,具有潜在的应用前景。目前,手性溶剂诱导方法适用范围已经涵盖了有机小分子、低聚物和聚合物体系。本文主要对手性溶剂诱导方法发展的历史背景,手性溶剂诱导小分子及低聚物的手性,手性溶剂诱导非手性聚合物产生超分子手性,主要包括π-共轭聚合物和σ-共轭聚合物这几个方面展开了综述。     

手性化合物

手性问题与我们的生活密切相关，它涉及到生命、动植物、药物、食品、香料、农药等诸多领域，本文介绍了手性化合物的一些性质、手性药物、手性化合物的拆分、尤其是手性化合物的现代色谱分离方法。     

手性杯芳烃及其超分子手性

杯芳烃是由苯酚单元通过亚甲基连接而成的空腔型分子,具有衍生位点多,构象丰富等特点,被称为第三代主体分子。在分子层次,依手性因素的结构特点不同,可将手性杯芳烃分为具有手性亚单元的杯芳烃、固有手性杯芳烃和桥手性杯芳烃。在超分子层次,杯芳烃自身或杯芳烃与其他分子或离子在溶液中、晶态中或二维表面可通过非共价键力形成多种拓扑结构的纳米手性聚集体。研究手性杯芳烃和基于杯芳烃的超分子手性组装体的合成、结构和性能,不仅在理解手性起源、手性结构等方面具有理论意义,而且有望获得以分子识别为基础的手性传感器、手性催化剂、手性分离材料、手性载体和手性纳米材料。本文综述近十年来有代表性的分子手性杯芳烃和以杯芳烃为组分的超分子手性聚集体的设计、合成、结构和功能。着重展示杯芳烃骨架在形成新颖分子手性和超分子手性上的优势,以及杯芳烃单元在实现特定功能如手性识别时发挥的作用。相信随着杯芳烃合成技术和杯芳烃超分子设计的发展,必将进一步发挥杯芳烃的结构优势,涌现出更多性能优异的手性杯芳烃功能分子和超分子手性杯芳烃功能材料。     

多肽超分子手性自组装与应用

多肽分子作为一类重要的生物手性小分子,能够通过分子自组装形成包括纳米螺旋、纳米管、手性凝胶等在内的有着独特生物效应和光学活性的手性纳米材料。这类材料具有易于功能化修饰的优点,在化学、生物、医药、材料科学等领域有着广泛应用,成功对多肽手性自组装结构进行精准多级调控,是进一步实现其功能化应用的基础。本文重点介绍了多肽分子氨基酸序列组成与构型等内部因素,以及溶液pH、溶剂、添加剂等外界因素对多肽分子手性自组装行为的影响,并归纳得出其关键作用机制;同时,还介绍了多肽手性自组装材料在手性催化、手性检测、模板合成、手性光学等领域的应用。     

一种手性中间体在键合型和涂覆型纤维素手性固定相上的拆分

制备了涂覆型和键合型纤维素-(3, 5-二甲基苯基氨基甲酸酯)固定相, 分别在制备的纤维素手性固定相上成功地拆分了一种手性中间体, 通过考察流动相中的改性剂(醇、四氢呋喃、三氯甲烷)对手性拆分的影响, 优化了手性中间体在两种手性固定相上的色谱分离条件, 并比较了手性中间体在涂覆和键合型纤维素手性固定相上的拆分. 结果表明, 涂覆型和键合型手性固定相对这种手性中间体均有较好的拆分效果, 在150 mm的色谱柱上, 这两种手性固定相对这种手性中间体的拆分能力相差不大, 但键合型固定相上可选择的流动相范围更广.     

手性离子液体在毛细管电泳手性分离中的应用

简要介绍了手性离子液体用于毛细管电泳手性分离的一般原理,系统地介绍了基于手性离子液体的毛细管电泳对映体拆分的一元手性选择体系和二元手性选择体系,并在国内外研究现状的基础上展望了手性离子液体在毛细管电泳手性分离中的应用前景。     

手性识别及氨基酸类手性固定相的研究进展

近年来, 手性识别更加凸现出极其重要的现实意义, 而作为分离手性分子应用的手性固定相自然引起了大家的关注．立足于国内外手性固定相的研究成果, 介绍了手性固定相及其分类, 并重点综述了基于氨基酸的手性固定相的发展及其制备方法. 同时, 简要介绍了作为手性固定相对不同异构体的识别机理.     

色谱手性分离研究

手性是自然界的基本属性之一,不同的手性单体具有不同的生理活性,将手性化合物有效的分离具有十分重要的意义.色谱法和膜分离法在拆分手性化合物中得到了越来越广泛的应用,也是我们课题组采用的主要方法.就近几年来拆分手性化合物的一些方法和研究成果本文进行综述,并对今后手性拆分技术的发展方向进行了展望.     

红霉素作为手性选择剂对手性药物的毛细管电泳拆分

以大环内酯类抗生素红霉素作为手性选择剂，在普通熔融石英毛细管上对两种酸性联苯双酯类保肝的性药物进行了毛细管电泳手性拆分研究；当用30mmol/L的红霉素、50mmol/L的磷酸盐体系（pH=6.0，含50％（Φ）的甲醇）时两种手性化合物的分离度分别为3.11和8.28，证明红霉素可以作为一种新的手性选择剂应用于毛细和泳手性分离中；通过实验研究了缓冲液种类及浓度、红霉素浓度、分离电压及温度、样品载入量、有机添加剂种类及含量对手性分离的影响。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.