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1.
利用气相色谱手性分析,对醇腈酶促不对称合成手性氰醇中的pH值、温度、底物浓度和水含量对酶反应速度和非酶反应速度的影响作了研究。结果表明,上述因素对酶反应和非酶反应速度均有显著影响。在水含量较低的非水相酶反应体系中,pH值在4.0以下或反应温度为0-5℃时,非酶反应受到较大程度的抑制,而酶反应仍具有相对较快的反应速度,故可获得高光学纯度的产物。 相似文献
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A Facile Synthesis of Squamosamide Cyclic Analogs 总被引:2,自引:0,他引:2
XiaoTianLIANG XiaoZhenJIAO PingXIE 《中国化学快报》2003,14(7):667-669
A series of novel cyclic derivatives have been synthesized by utilizing a nickel powder mediated radical cyclization as the key step. The structures of the new compounds were confirmed by ^lH-NMR and MS. 相似文献
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IntroductionOrganomercurials have been used extensively in organic synthesis and synthesis of other organometallics due to their ability to accommodate practically all the important organic functional groups and their ease in undergoing transmetallation for syntheses of transition metal organometallics which are very useful in organic synthesis. Recently, we reported the synthesis of optically active 1,2-disubstituted cyclomercurated ferrocenylimines by transmetallation reaction of planar chir… 相似文献
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杂氮钛三环(titatrane)(Ⅰ)是一类具有五配体特殊结构的杂环化合物,由于对其合成工作研究的不多,所以这类化合物的一些性质还鲜为人知。我们对杂氮钛三环的合成方法做了改进,将手性中心引入到这类化合物中,合成了下列结构图中(Ⅱ)所示的具有手性的杂氮钛三环。 相似文献
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合成了两个新型的艾溴利平类似物——N-2 -硝基-4-氯苯基-4-[(膦酸二乙酯基)甲基]苯甲酰肼(5,总收率28.1%)和N-2-四氮唑基-4-氯苯基-4-[(膦酸二乙酯基)甲基]苯甲酰胺(7,总收率30.5%).以对氯甲基苯甲酸为原料,经酯化、水解和酰氯反应制得中间体4-[(膦酸二乙酯基)甲基]苯甲酰氯(4);4与2-硝基-4-氯苯肼盐酸盐反应合成了5.4先与2-氨基-5-氯苯腈反应制得N-2-氰基-4-氯苯基-4-[(膦酸二乙酯基)甲基]苯甲酰胺(6);6再与叠氮化钠反应合成了7.其结构经1 H NMR和IR表征. 相似文献
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Yu Hua ZHANG Wei Qiang ZHANG Yu Gang CHEN Zhi CHEN Xin Yi ZHU Huan Wang JING Yuan Qi YIN* State Key Laboratory for Oxo Synthesis Selective Oxidation Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Lanzhou 《中国化学快报》2001,(1)
Due to the framework chirality optically active clusters can provide the proof that a cluster as a whole, and not one of its fragments, acts as a catalyst, most of the work have been directed to the synthesis of tetrahedron-type chiral clusters1-3. However, there remains another major problem to obtain the pure enantiomers. Although Vahrenkamp had obtained some pioneering results in this area before 19901, only several racemic chiral clusters have been separated into pure enantiomers until now… 相似文献
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Bagnoli L Scarponi C Rossi MG Testaferri L Tiecco M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(3):993-999
The reactions of readily available vinyl selenones with enantiopure 1,2-diols, N-protected-1,2-aminoalcohols, and diamines gave substituted enantiopure 1,4-dioxanes, morpholines, and piperazines, respectively, in good to excellent yields. The same procedure was extended to the synthesis of thiomorpholine, benzodiazepine, and benzoxazepine. The reactions proceeded in one pot, in the presence of base, through a simple and novel application of the Michael-initiated, ring-closure (MIRC) reactions. The formed heterocycles constitute a framework that is observed in a large number of pharmaceutical compounds. 相似文献
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Yasuhiro Morisaki Dr. Yuko Ouchi Kensuke Naka Dr. Yoshiki Chujo Prof. Dr. 《化学:亚洲杂志》2007,2(9):1166-1173
A series of optically active P‐chiral oligophosphines (S,R,R,S)‐ 2 , (S,R,S,S,R,S)‐ 3 , (S,R,S,R,R,S,R,S)‐ 4 , and (S,R,S,R,S,R,R,S,R,S,R,S)‐ 5 with four, six, eight, and 12 chiral phosphorus atoms, respectively, were successfully synthesized by a step‐by‐step oxidative‐coupling reaction from (S,S)‐ 1 . The corresponding optically inactive oligophosphines 1′ – 5′ were also prepared. Their properties were characterized by DSC, XRD, and optical‐rotation analyses. While optically active bisphosphine (S,S)‐ 1 and tetraphosphine (S,R,R,S)‐ 2 behaved as small molecules, octaphosphine (S,R,S,R,R,S,R,S)‐ 4 and dodecaphosphine (S,R,S,R,S,R,R,S,R,S,R,S)‐ 5 exhibited the features of a polymer. Furthermore, DSC and XRD analyses showed that hexaphosphine (S,R,S,S,R,S)‐ 3 is an intermediate between a small molecule and a polymer. Comparison of optically active oligophosphines 1 – 5 with the corresponding optically inactive oligophosphines 1′ – 5′ revealed that the optically active phosphines have higher crystallinity than the optically inactive counterparts. It is considered that the properties of oligophosphines depend on the enantiomeric purity as well as the oligomer chain length. 相似文献
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Prof. Dr. Santos Fustero Lidia Herrera Ruben Lázaro Elsa Rodríguez Dr. Miguel A. Maestro Dr. Natalia Mateu Pablo Barrio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(35):11776-11785
The nucleophilic addition (AN) / intramolecular aza‐Michael reaction (IMAMR) process on Ellman’s tert‐butylsulfinyl imines, bearing a Michael acceptor in the ortho position, is studied. This reaction affords 1,3‐disubstituted isoindolines with a wide range of substituents in good yields and diastereoselectivities. Interestingly, careful choice of the base for the aza‐Michael step allows either the cis or the trans diastereoisomers to be exclusively obtained. This stereodivergent cyclization has enabled the synthesis of C2‐symmetric bisacetate‐substituted isoindolines. In addition, bisacetate isoindolines bearing two well‐differentiated ester moieties are also noteworthy because they may allow for the orthogonal synthesis of β,β′‐dipeptides using a single nitrogen atom as a linchpin. 相似文献
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Piceatannol,(E)-3,3′,4,5′-tetrahydroxy stilbene, a natural polyhydroxy stibene, possesses many biological activities, its synthesis has been reported. We designed another route of its synthesis, which can be controlled more easily. The synthetic product was characterized by elemental analysis,IR,MS and ^1H-NMR. Its analogs were synthesized by the similar method. 相似文献
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Dilyara R. Chulakova Ambara R. Pradipta Olga A. Lodochnikova Danil R. Kuznetsov Kseniya S. Bulygina Ivan S. Smirnov Konstantin S. Usachev Liliya Z. Latypova Almira R. Kurbangalieva Katsunori Tanaka 《化学:亚洲杂志》2019,14(22):4048-4054
The chiral substituted 1,5‐diazacyclooctane (1,5‐DACO) is of considerable importance and has attracted attention from a wide range of fields due to their unique chemical and biological properties. Despite the application potential, further study has not been optimized due to difficulties in their synthetic accessibility. Here, we report that the 1,5‐DACO bearing a chiral auxiliary obtained from the formal [4+4] cycloaddition of N‐alkyl‐α,β‐unsaturated imines can be further derivatized by nucleophilic alkylation to give various chiral substituted 1,5‐DACO derivatives. The removal of the chiral auxiliary was effectively carried out using hydrogenation over Pearlman's catalyst. This methodology allows the production of a broad range of unprecedented optically active 2,6‐dialkyl‐1,5‐DACO, which could not be accessed by other methods. 相似文献
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Ci Song Xuan Liu Dong Liu Chonglei Ren Wantai Yang Jianping Deng 《Macromolecular rapid communications》2013,34(18):1426-1445
Particles constructed by chiral polymers (defined as PCPs) have emerged as a rapidly expanding research field in recent years because of their potentially wide‐ranging applications in asymmetric catalysis, enantioselective crystallization, enantioselective release, amongst many others. The particles show considerable optical activity, due to the chirality of the corresponding polymers from which the particles are derived. This review article presents an overview on PCPs with emphasis on our group's recent achievements in the preparation of PCPs derived from optically active helical polymers and their applications. PCPs can be prepared via emulsion polymerization, precipitation polymerization, and suspension polymerization by starting from monomers. Emulsification of preformed chiral polymers and self‐assembly approaches also can lead to PCPs. Chiral polymer‐based core/shell particles, hollow particles, and magnetic particles are also covered because of their remarkable properties and significant potential applications.
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Dr. Hai-xuan Liu Dr. Fei Ji Yu Chen Ya Gao Jun-ke Wang Dr. Ming-zhi Zhang Dr. Fang Liu Dr. Qiang Sha 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(16):5225-5229
Herein, a divergent synthesis of a variety of 2α- and 5α-substituted furan derivatives from 2-hydroxy-1,4-diones is reported. By using appropriate substrates and an acid catalyst, the reactions occurred selectively through cyclization/1,6-conjugate addition or cyclization/Friedel–Crafts-type cascade reactions. A broad range of nucleophilic reagents (>10 types for the 1,6-conjugate addition for 5α substitution and >20 types for the Friedel–Crafts-type cascade reaction for 2α substitution), including alcohols, amides, furan, thiophene, pyrrole, indole, phenols, and many others, can successfully participate in the reactions, providing a universal strategy for a diversity-oriented synthesis of α-substituted furan derivatives. Deuteriation experiments and DFT calculations were carried out to support the proposed reaction mechanisms. Antifungal activity experiments revealed that products with an indole or 4-hydroxycoumarin core substituted at the 2α position showed moderate activities against Rhizoctorzia solani and Botrytis cinerea, respectively. 相似文献
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Yu Sun Pengxi Chen Deliang Zhang Martin Baunach Prof. Dr. Christian Hertweck Prof. Dr. Ang Li 《Angewandte Chemie (International ed. in English)》2014,53(34):9012-9016
The first total synthesis of sespenine, a rare indole sesquiterpenoid from a mangrove endophyte, has been accomplished. A bioinspired aza‐Prins/Friedel–Crafts/retro Friedel–Crafts cascade reaction assembles the bridged tetrahydroquinoline core. Further investigations on the aza‐Prins cyclization imply that the C3 configuration of the hydroxyindolenine intermediate is crucial to the biosynthesis of sespenine and its congener xiamycin A. 相似文献
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FUYing-huan CHENJin WUTong-hao BAIXu 《高等学校化学研究》2005,21(4):476-479
To investigate the recovery of amino alcohols as chiral auxiliaries, optically active p-benzyloxyphenylglycinol and its corresponding oxazolidine of 1-naphthylcarboxaldehyde were prepared. Grignard additions to the oxazolidine followed by electrophilic quench and acidic hydrolysis afforded an aldehyde( compound 8) (later it was reduced to an alcohol, compound 9) in an excellent enantiomeric excess and a good recovery of the chlral amino alcohol. This research provides a model study of chiral amino alcohols in solid phase asymmetric synthesis. 相似文献
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Enantiomerically pure bis‐heterocycles containing a (S)‐proline moiety have been prepared starting from (S)‐N‐benzylprolinehydrazide ( 2b ). The reactions with isothiocyanates or butyl isocyanate in refluxing MeOH led to the corresponding thiosemicarbazide 5 and semicarbazide 9 with a N‐benzylprolinoyl residue. The structure of the tert‐butyl derivative 5d was established by X‐ray crystallography. Base‐catalyzed cyclization of 5 and 9 led to (S)‐3‐(pyrrolidin‐2‐yl)‐1H‐1,2,4‐triazole‐5(4H)‐thiones 6 and the corresponding 5(4H)‐one 8 , respectively, whereas, in concentrated H2SO4, compounds 5 undergo cyclization to give (S)‐5‐amino‐2‐(pyrrolidin‐2‐yl)‐1,3,4‐thiadiazoles 7 . Furthermore, 2b reacted with hexane‐2,5‐dione in boiling iPrOH to yield the (S)‐N‐(2,5‐dimethylpyrrol‐1‐yl)prolinamide 10 . In the case of the bis‐heterocycle 8 , treatment with HCOONH4 and Pd/C in MeOH gave the debenzylated product 12 . 相似文献