关键词： 硝基   联萘酚   芳香化合物   不对称合成   手性拆分   取代反应   衍生物   专利   应用   芳环  

摘要： 　　1,1′-联-2-萘酚及其衍生物是近年来被研究较多的C2轴不对称芳香化合物,它在手性拆分和不对称合成中都有着重要的应用,这方面已经有许多综述[1].但有关联萘酚芳环上的亲电取代反应中较常见的是6位上的溴取代,双硝基取代的化合物仅在一篇专利中有提到[2],而单硝基取代的则未见有报道.……

关键词： 羟甲基化   羟基衍生物   不对称合成   异斯特维醇   甜叶菊苷   生物生理活性   二萜类化合物   新药开发   晶体结构测定   抗肿瘤活性   应用前景   酸性水解   手性药物   生物活性   生物合成   氢化反应   光学活性   资源   文献   理论  

摘要： 　　异斯特维醇(Isosteviol)是一种贝叶烷二萜类化合物,具有广泛的生理活性,可由甜叶菊苷(Stevioside)经酸性水解得到.从异斯特维醇出发,利用其合适的二萜骨架,可以衍生出各种具有生物活性和光学活性的多羟基衍生物和具有抗肿瘤活性的其它衍生物.我国甜叶菊苷资源非常丰富,开发异斯特维醇衍生物的化学或生物合成,研究其生物生理活性、探讨其在新药开发和在不对称合成中的应用,具有重要的理论意义和应用前景.本文以甜叶菊苷(Ⅰ)为起始物,经水解制得异斯特维醇(Ⅱ),再经羟甲基化和氢化反应,可方便制得未见于文献报导的15-β-羟甲基16-α-羟基异斯特维醇衍生物(Ⅲ).经EA,IR,1H NMR,13C NMR和晶体结构测定,确定了化合物Ⅲ的结构.预期这类化合物具有某种生理活性,可用于手性药物的开发研究.……

关键词： 1,1′-联萘-2,2′-二胺   制备   应用   不对称合成   消旋体联萘胺   光学活性联萘胺  

摘要： 综述了 1,1′ 联萘 2 ,2′ 二胺 (联萘胺 )化合物的制备 ,讨论了它们作为手性辅助基或配体在烯烃、酮、亚胺的不对称氢化及在烯烃的不对称环丙烷化、醛的烷基化反应、醛的不对称烯丙基化反应、不对称烯丙位取代反应和不对称Diels Alder反应等反应中的应用 .

关键词： 手性配合物   不对称合成   应用研究   类催化剂   金属离子   环己二胺   对称反应   地位  

摘要： 　　基于手性1,2-环己二胺Salen配体在不对称合成中具有极重要的地位,其与金属离子形成的手性配合物催化许多不对称反应,取得了好的结果.因此此类催化剂的合成及其应用研究一直是不对称合成中的一个热点.……

关键词： 应用   甲基苄胺   不对称合成   诱导合成   手性配体   二羟基   双喹啉   光学纯   诱导体  

摘要： 　　光学纯6,6′-二羟基-5,5′-双喹啉(BIQOL)是近年来发展的一个优秀的新型含N手性配体.我们应用(+)-α-甲基苄胺作为手性诱导体,不对称合成BIQOL,这种新的尝试是不对称合成光学纯6,6′-二羟基-5,5′-双喹啉的第一个例子.……

关键词： 烷化作用   氨基酸类/化学合成   氨基酸类/化学   催化作用   酯类   亚氨酸类/化学合成   亚氨酸类/化学   立体异构现象   β内酰胺类/化学合成   β内酰胺类/化学  

摘要： The catalytic asymmetric addition of organic nucleophiles to alpha-imino esters has emerged as one of the most promising and intensely investigated routes to optically enriched alpha- and beta-amino acid derivatives and beta-lactams. The importance of alpha-imino esters stems not only from the vast appeal of the potential product classes,(1) but also from their remarkable reactivity as highly electrophilic imines. With each passing year, the number of publications concerning the asymmetric alkylation of imino esters grows significantly. The asymmetric alkylation of imines(2) and N,O-acetals has been in itself a subject of intense interest.(3) In this Account, we wish to illustrate our contribution to this timely field, as well as to highlight the seminal contributions of others.

关键词： nucleosides   sulfur heterocycles   chirality   sulfoxides   antiviral agents  

摘要： We report the ready asymmetric synthesis of nucleoside analogues containing a 1,3-dithiolane ring that mimics the sugar moiety of natural nucleosides. The synthesis is accomplished in three main steps from benzoyloxyethanal 1,3-dithiolane, the key step being its conversion into a chiral monosulfoxide by a modified Sharpless sulfo-oxygenation reaction. The nucleoside analogues were obtained in good overall yields and with excellent enantiomeric excesses. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).

关键词： nitrogen heterocycles   asymmetric synthesis   cyclisation   amino acids  

摘要： (S)-4-Oxopipecolic acid has been prepared in enantiomerically pure form from two readily accessible starting materials, (R)-N-(cyanomethyl)-4-phenyloxazolidine (2) and 2(methoxymethoxy)allyl chloride, (3, MOM-allyl chloride). This strategy exploits the complementary electrophile/nucleophile reactivity at each end of this pair of 3-atom unit building blocks. Thus, alkylation of the anion of 2 with 3 (creation of the piperidine C-2-C-3 bond) followed by Lewis acid induced cyclisation (creation of the C-5-C-6 bond), leads principally to a bicyclic intermediate 5 which incorporates a protected form of the title compound. Subsequent chemical transformations lead to the target molecule in an overall yield of 20% for the five-step sequence. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).

关键词： .Branched   additions   tert-butyl   imines   nucleophiles   diastereoselectivity   high yields   asymmetric synthesis   enantiomerically pure   amino alcohols   inexpensive   Applications of tert-butanesulfinamide   tert-butanesulfinyl group  

摘要： tert-Butanesulfinamide is prepared using catalytic enantioselective methods in two steps from the extremely inexpensive oil waste by-product, tert-butyl disulfide. Direct condensation of tert-butanesulfinamide with aldehydes and ketones provides tert-butanesulfinyl imines in uniformly high yields. The tert-butanesulfinyl group activates the imines for the addition of many different classes of nucleophiles, serves as a powerful chiral directing group, and after nucleophilic addition is readily cleaved by treatment with acid. A wide range of highly enantioenriched amines, including alpha-branched and alpha,alpha-dibranched amines, alpha- and beta-amino acids, 1,2- and 1,3-amino alcohols and alpha-trifluoromethyl amines are efficiently synthesized using this methodology.

关键词： complex potential approach   unsymmetrical composite laminates   stress resultants and moments   holes  

摘要： Stress resultants and moments around the holes of infinite unsymmetrical composite laminates under remote uniform loading are analyzed using the complex potential approach developed by Chen and Shen [Mech. Res. Commun. 28, (4) (2201) 423: 28 (5) (2001) 513]. In the analysis, the authors' previous work has been modified to determine the complex constants B-k appeared in the complex potential functions of Chen and Shen [Mech. Res. Commun. 28 (5) (2001) 513], Herein B-k are the unknown quantities related to the remote loading conditions. The effect of bending extension coupling has been discussed for several laminates such as [0/90](T), [45/-45](T) and [0/90/45/-45](nT). Results indicates that the coupling, between bending and extension significantly affects the stresses around the hole of an unsymmetrical laminate containing one sub-laminate only. Such the effect rapidly decreases as the number of the sub-laminates increases. The results confirm the validity of the developed complex potential approach, (C) 2002 Elsevier Science Ltd. All rights reserved.