关键词： 香叶   基丙酮   氰基硅醚   手性亚砜  

摘要： 该论文是以联降二萜类天然产物Hedaol B的全合成及其不对称研究,和利用手性亚砜应用于天然产物(3S,6R)3,6-二羟基-10-甲基十一酸,苯并螺环缩酮类天然产物的合成为研究对象,包括以下四个部分:1.以香叶基丙酮为起始原料,通过七步反应首次完成(±)Hedaol B的全合成,其中关键反应为氰基硅醚的烷基化反应;另外我们还对(-)Hedaol B的不对称合成做了探索.2.分别以异戊基溴和乙酰乙酸甲酯为起始原料,经过多步反应合成天然产物(3S,6R)3,6-二羟基-10-甲基十一酸两个关键中间体50和54,并对50和54的烷基化反应进行了研究.3.对苯并螺环缩酮类天然产物如何构筑螺环季碳中心手性进行了初步研究,提出了利用手性亚砜不对称诱导来构筑螺环手性中心.4.就手性亚砜在天然产物的不对称合成听应用进行了简要综述.

关键词： α-吡喃酮类   天然产物   肉桂醛   脱羟基反应   呋喃甲醇类化合物   动力学拆分  

摘要： 该论文工作以α-吡喃酮类天然产物的不对称合成研究为主要研究目的,主要内容如下:一、以廉价易得的肉桂醛为起始原料,通过Sharpless不对称环氧化试剂对呋喃甲醇类化合物6进行动力学拆分,然后采用Mitsunobu转化等关键步骤,经过8步反应,首次完成了5-Acetyl goniothalamin 1和5-Acetyl isogoniothalamin oxide 2的不对称合成并确定了5-Acetyl goniothalamin 1的构型为(5S,6S).二、利用Sharpless不对称环氧化对呋喃甲醇类化合物6进行动力学拆分的产物12经过高效的脱羟基反应等关键步骤,以8步化学操作,简洁高效的完成了(6R)-Goniothalamin 3和(6R,7S,8S)-Gniothalamin oxide 4的不对称合成.三、Sharpless不对称环氧化试剂对呋喃甲醇类化合物6进行动力学拆分和Mitsunobu转化等关键反应所得的产物12进行如下化学操作:(1)增大位阻效应,立体选择性的在7、8位双键上的α-面环氧化,(2)利用弱酸PPTS选择性关环等关键步骤,共通过11步反应成功完成了(+)-Isoaltholactone 5的不对称合成.

关键词： 除草剂   R-(+)-2-(4-羟基苯氧基)丙酸酯   不对称合成   苯氧丙酸   农药中间体  

摘要： 报道了一种合成苯氧丙酸类除草剂重要中间体R (+) 2 (4 羟基苯氧基 )丙酸乙酯 (即R (+) HPE)的方法 ,以L 乳酸为起始原料 ,先经酯化合成L 乳酸乙酯 ,再与对甲苯磺酰氯反应制备L 对甲苯磺酰乳酸乙酯 ,再与对苯二酚缩合获得R (+) 2 HPE ,产品的总收率为 72 1 %。通过元素分析和红外光谱测定 ,确定了所合成的R (+) HPE的化学结构和纯度 ;由旋光度的测定 ,确定了所合成的R (+) HPE的光学纯度为 95 7%。

关键词： 昆虫信息素   L-脯氨酸   大环二萜天然产物   不对称全合成   西松烷型大环二萜   氧化反应   Aldol反应  

摘要： 本论文工作以四种昆虫信息素的不对称合成以及西松烷型大环二萜类天然产物(+)-Methy1cembra-1，3，7，11-tetraene-16-carboxynate的不对称全合成为主要研究对象；同时对L-脯氨酸催化的环丁酮与各种醛的不对称Aldol反应进行了研究。\n 全文共包括以下三个部分：一、四种昆虫信息素的不对称合成研究。二、西松烷型二萜类天然产物的首次不对称合成研究。三、昆虫信息素合成进展(1990-2004年)。\n　　综述了1990年到2004年间昆虫信息素的合成进展，内容涉及烯键构筑和手性中心建立两个方面：主要有机硼化物反应，Sharpless不对称反应，RCM反应，生物选择性立体催化反应以及其他不对称反应。本论文共完成两种昆虫信息素的合成、一种西松烷型二萜天然产物的全合成；并且发展了L-脯氨酸催化环丁酮的不对称Aldol反应，并对两种昆虫信息素的合成进行了初步研究。实验发现，L-脯氨酸催化环酮的不对称Aldol反应以syn产物为主；并为有五元环、六元环内酯结构的天然产物的骨架建立提供了一条简便易行、ee值较高的方法。全文共涉及65个化合物的合成，其中30个为首次报道的新化合物，它们的结构均由IR、MS、NMR证实。

关键词： Anti-Inflammatory Agents   Non-Steroidal   Glucocorticoids   Heterocyclic Compounds with 4 or More Rings   Stereoisomerism  

摘要： A new approach for atropselective preparation of axially chiral biaryl was developed. This process proceeded through a chirality transfer from a stereogenic center of a secondary alcohol to the stereogenic axis via regioselective intramolecular silyl group migration, This methodology allowed for the preparation of a single atropisomer 2 in good yield (85%) with high diastereoselectivity (99:1), which subsequently led to the successful development of an efficient asymmetric synthesis of A-240610.0, 1.

关键词： HYDROXYACETOPHENONES   ALDEHYDES   ALKENES  

摘要： An anti-selective direct catalytic asymmetric aldol reaction of 2-hydroxyacetophenones with aldehydes is described. The reaction is catalyzed by a heteropolymetallic complex to afford anti-alpha,beta-dihydroxy ketones as the major diastereomer with excellent enantioselectivity. The use of 2-hydroxyacetophenones bearing electron-donating groups at the phenyl moiety enabled efficient transformation of the aldol products (alpha,beta-dihydroxy ketones) into the corresponding alpha,beta-dihydroxy ester derivatives via Baeyer-Villiger oxidation. A plausible reaction mechanism is also discussed based on the stereochemistry of the products.

关键词： Redox reactions   Diols   Organic compounds   Molecular structure   Piperidines  

摘要： [GRAPHICS] trans-6-Aminocyclohept-3-enols 18 and ent-18 are new designed polyfunctionalized chiral building blocks for piperidine alkaloids synthesis and are prepared in high yields from the enzymatically derived cyclohept-3-ene-1,6-diol monoacetate (-)-8. Efficient highly enantioselective syntheses of cis-4-hydroxypipecolic acid (1) and piperidines 3 and 4, in both enantiomeric forms, are described.

关键词： asymmetric synthesis   Michael addition   natural products   oxidation   quinones  

摘要： A short and convergent approach for the synthesis of alkannin, shikonin and shikalkin is presented. A Hauser-type annulation of cyanophthalide 26 with enone 7 affords the complete aromatic system in just one step with concomitant attachment of the entire side chain. Subsequent Corey's oxazaborolidine mediated asymmetric reduction of the above advanced intermediate, leads to the required isomer in high enantiomeric excess. Finally, a selective and high yielding deprotection protocol furnishes the title compounds as pure crystalline precipitates. Thus, a multigram synthesis of shikonin, alkannin and shikalkin is achieved in high yield and enantioselectivity.

关键词： AMINO acids   STEREOCHEMISTRY  

摘要： The development of a highly efficient and stereoselective methodology for the preparation of alpha-amino acids is described. The chiral template, tricyclic iminolactone 7, was synthesized from (1R)-(+)camphor in five steps in 50% overall yield. Alkylation of iminolactone 7 afforded the CL-monosubstituted products in good yields (74-96%) and excellent diastereoselectivities (>98%). Hydrolysis of the alkylated iminolactones furnished the desired alpha-amino acids in good yields and enantioselectivities with nearly quantitative recovery of the chiral auxiliary 4.

关键词： Alcohols   aldehydes   pyran   Asymmetric synthesis   cis   allylation  

摘要： [GRAPHICS] A reaction process for the asymmetric construction of a variety of cis or trans disubstituted pyrans is described. This sequences allows for the asymmetric convergent union of two aldehydes with silyl-stannane reagent I in a two-step process: catalytic asymmetric allylation of the first aldehyde using 1 with a BITIP catalyst, followed by reaction of the alcohol so obtained with a second aldehyde and TMSOTf.