关键词： Reagents   Group 14 compounds   Adducts   Aldehydes   Transition states  

摘要： Marshall discusses additions of chiral organotin compounds to chiral and achiral aldehydes leading to intermediates for polypropionate and carbohydrate synthesis.

关键词： 不对称   开放实验室   有机合成反应   基金资助  

摘要： １９９６年不对称合成联合开放实验室科学基金资助的申请指南一、研究方向：本实验室的研究方向是研究有机合成反应中的立体控制合成，发展既能高产率，又能高光学纯度地制备的光学活性异构体的新方法，研究有机合成反应中不对称诱异、立体控制的内在规律性，寻求和发展立...

关键词： 类似物   石油醚   光学活性   不对称合成   化合物   异丁醛   合成研究  

摘要： 藁本酚是本课题组对藁本属植物进行深入研究时，从藁本根茎中分离到的新的倍半萜类化合物，具有较强的免疫抑制、抗炎活性。通过对该化合物CD谱的研究，确证了它的绝对构型为S-型。为了进一步研究该化合物的药理活性，对其进行了合成研究。以异丁醇、间甲酚为起始原料，经氧化、溴取代、芳烃碘代、羟基保护、格氏反应、Aldol缩合反应，脱保护等七步反应完成了外消旋藁本酚的全合成。 经1H-NMR，MS，IR分析，并与天然产物藁本酚图谱比较，目的物得到证实。 为了研究藁本酚药理作用类型，寻找药效团，研究构效关系，利用药物设计的基本原理，设计并合成了六个类似物。深入的药理研究正在进行中。 为了研究藁本酚的立体异构体对药理活性的影响，又设计了一系列光学活性藁本酚的类似物。并对藁本酚及其类似物进行了不对称合成的探索研究。 全文共合成了32个目标物及中间体，其中17个化合物未见文献报导。

关键词： 合成技术   精细化学工业   不对称   手性中心   中国科学院上海有机化学研究所   上海有机化学研究所  

摘要： 不对称合成技术姜标（中国科学院上海有机化学研究所）当前国际化学工业的重点已开始从大品种的化学产品和高聚物逐渐向生产中小型的高精化学产品转移。后者包括医药、农用化学品、香精和特殊化学中间体。这些化学品往往具有复杂的化学结构和手性中心。手性是宇宙间普遍的...

摘要： This thesis describes three new approaches to the asymmetric synthesis of chiral proline derivatives from (R) and (S)-tert-butyl-3-benzoyl-4-methylene-2-oxazolidin-5-one. In the first Chapter, some important aspects of proline derivatives, specially the strategies used for the synthesis of these compounds was presented. It was found that for the preparation of proline derivatives in high enantiomeric purity, starting materials with a chiral auxiliary have generally been employed. In Chapter Two, the Michael addition reactions of the pyrrolidine enamines (223- 225) to (S)-2-tert-butyl-3-benzoyl-4-methylene-oxazolidin-5-one (222) and its enantiomer, (R)-(222), to give Michael addition adducts of the type (226) was examined. The Michael addition reactions of the pyrrolidine enamines (223) and (225) to the chiral oxazolidinones (S)-(222) or (R)-(222) favours cis 2,4-disubstituted oxazolidinone adducts while trans 2,4-disubstituted oxazolidinone adducts were favoured from the addition reactions of enamine (224). The diastereomeric adducts from the addition of (223) to (222) were readily separated and were converted to (5R, 2S) and (5S,2R)-cis-5-iso-propylproline, efficiently in good overall yields and in high enantiomeric purities. The extension of this protocol to the synthesis of (2S, 3aS, 7aS)- perhydroindole carboxylic acid (3) suffered from poor overall stereochemical control and a mixture of two diastereoisomeric products reasulted. In Chapter Three, the synthesis of polyfunctionalized proline derivatives via the asymmetric 1,3-dipolar cycloaddition reactions of azomethine ylides derived from N-alkylidene or N-arylidene imino esters (201), with the chiral oxazolidinone (222) as a dipolarophile, have been presented. The cycloadducts were obtained with a high degree of regio- and diastereoselectivity that resulted from addition of the dipole to the exo-cyclic methylene group of the oxazolidinone (222) from the less hindered side of the oxazolidinone ring. Good endo-d

摘要： The aryl propanoic acid ibuprofen ((S)-2 -14-(2-methylpropyl)phenyllpropanoic acid) was synrhesized in 96Vo e. e. Control of stereochemistry was achieved by use of the Sharpless epoxidation reaction, followed by reduction of the product epoxide by complex hydride with assistance by titanium tetraisopropoxide acting as a Lewis acid' The final step was the coupling of an optically active carboxylic acid intermediate with the iso-butyl side chain to give (S)-ibuprofen. This intermediate is a bromo arene and could potentially be coupled to various side chains to give different members of the aryl propanoic acid family. The synthesis of naproxen ((D-2-(6-methoxy-2-naphthyl)propanoic acid) was also completed, in 96Vo e. e. Asymmetry was int! oduced with the Sharpless asymmetric dihydroxylation reaction followed by formation of the corresponding optically active epoxide. This epoxide was reduced by catalytic hydrogenolysis of the benzylic C-O bond to give the stereogenic centre with the correct configuration. The final step was oxidation to give naproxen. The synthesis of ketorolac ((S)-5-benzoyl- 1,2-dihydro-3EI-pyrrolo[ 1,2-o]pyrrole- 1-carboxylic acid) was attempted. A target intermediate was sought, from which the methodology established above, for the synthesis of naproxen, could be used to establish the stereogenic centre adjacent to the carboxylate group, This intermediate, ftom which point asymmetric chemistry would be attempted, was a diketone, which had two carbonyl groups in direct conjugation with the pynole ring. Many problems were experienced in the preparation of this intermediate, in attempts to attach the second carbonyl group, due to the deactivating narure of the already attached, electron withdrawing, carbonyl group. The intermediate was not obtained in workable quantities. Another route was attempted, in which the intermediates were not stabilized by the benzoyl group, however these intermediates were too unstable,". h-Y. iatl It was not realised at th

关键词： 液晶   鐵電性   光活性層列C 相   自發極化   不對稱合成   共融混合物   顯示技術  

摘要： 铁电性液晶近来的发展相当活泼，逐渐受到化学界的注目；本文对其历史、原理、分子结构设计、物性、合成方法、实用性混合物的调制及应用面等做一综合性的介绍。

关键词： 氨基   羟基   苯基戊酸   不对称合成   吡咯烷生物碱  

摘要： 吡咯烷生物碱及相关化合物的不对称合成研究（Ⅰ）黄培强，阮源萍（厦门大学化学系，厦门，３６１００５）关键词Ｐｒｅｕｓｓｉｎ，４－氨基－３－羟基－５－苯基戊酸，不对称合成，酰胺－α－烷基化，１．５－二苄基－４－苄氧基－２－吡咯酮（＋）－ｐｒｅｕｓｓｉｎ１...

摘要： The thesis entitled ASYMMETRIC SYNTHESIS USING NOVEL CHIRAL AUXILIARIES AND THE SYNTHESIS OF NOVEL HOST MOLECULES embodies the results of our investigations in the area of asymmetric synthesis. > An introduction to the thesis highlighting the various methods that are commonly employed in the synthesis of optically active compounds is given in the first chapter. This includes a brief description of the classical methods of nsynunetric synthesis and a selective but more dqtailed account of the use of chiral catalysts and auxiliaries. Chapter 2 deals with the synthesis of optically active ']-pl1€l1yl-'y- butyrolactone (6a) and 8-phenyl-8-valerolactone (6b) in optically active form using deoxycholimacid In and cholic acid lb as chiral auxiliaries. The strategy involves attachment of prochiml moieties containing keto youp to the auxiliaries followed by reduction of the keto group under various conditions to aflord the hydroxy esters. The auxiliaries are removed by saponification to afford the laetones 6: and 6b in optically active form. Modest ee values (upto 47%) are obtained when the ketoester derived from 1: is reduced using NaBH4 in presence of ZnCl2. A transition state model is proposed to explain the results. It is observed that temperature does not have any appreciable eflect on me level of chiral induction. A facile synthesis of the anhydrofuranosides 2a and 2b along with their use as auxiliaries in the synthesis of optically active lactones constitutes the subject matter of the third chapter. y-phenyl-ry-bixtyrolactone (En), 8-phenyl-8- butyrolactone (Sb), y-methyl-'y-butyrolaetone (8c) and 5-rnethyl-8-valerolactone (8d) are obtained with good ee values especially when 2b is used as the chiral auxiliary. An ee value of 93% is obtained for 8:, when the reduction is carried out using NaEH4 in presence of ZnCl2 and this compares favourably with that obtained by the enzymatic methods. A rationalization of the results in the light of a transition state model is also inc