关键词： 离子液体   不对称合成   对映选择性   催化反应   综述  

摘要： 综述了近年来离子液体在不对称催化反应中的应用,包括不对称Aldol反应、不对称氟化反应、酶催化的不对称还原反应、不对称催化氢化反应、不对称硅腈化反应、不对称环丙烷化反应、烯丙基的不对称取代反应、环氧化物的不对称开环反应、不对称环氧化反应、烯烃的不对称双羟基化反应、酶催化的醇的动力学拆分。参考文献43篇。

关键词： 氟苯尼考   抗生素   不对称合成   异构体  

摘要： 以D 苏式 2 氨基 1 [(对 甲砜基)苯基] 1,3 丙二醇为起始原料,与二氯乙腈进行不对称合成,在手性有机锌、YH 3催化剂作用下进行合成、结构转化,减少了副产物生成,是合成氟苯尼考新工艺的探讨。

关键词： 磷霉素   对映体过量值   镧系位移试剂  

摘要： 通过加入镧系位移试剂Eu(tfc)3(三氟乙酰基-d-樟脑酯根合铕),测定磷霉素催化不对称合成产物的1HNMR图谱,由峰面积计算对映体过量值(ee值)。

关键词： 手性催化剂   Michael加成反应   镧配合物   不对称合成   羟醛缩合反应   手性化合物   手性冠醚   环己酮   丙烯腈   手性醇  

摘要： It is one of the most attractive types of asymmetric synthesis that chiral commpounts are generated under the influence of chiral catalysts. In recent years catalytic asymmetric Michael addition by chiral metal complexes has been recognized as an efficient method for obtaining asymmetric products. In this work we reported that using potassium thiazolidine -2-thione-4-carboxylate [(R)-TTCA·K] as the chiral catalyst, the addition reaction of cyclohexanone with acrylonitrile was carried out and optically active (S)-(+)-2-cyanoethyl cyclohexanone 1 ([α] 20 D=+2.8°, e.e. 19%) and hydrolysis product of 1, (S)-(-)-2-oxocyclohexanepropionic acid 2 ([α] 20 D=-2.95°, e.e. 19%), were obtained. Enantiomeric excess of compound 1 was determined by resolution of (R,S)-2-oxocyclohexanepropionic acid with (-)-quinine. Compounds 1 and 2 were easily racemized at a long time for laying aside and in the presence of dil H 2SO 4 or dil base. When (S)-(+)-2-cyanoethyl cyclohexanone reacts with ethylene glycol in the presence of toluene sulfonic acid as the catalyst the racemic 2-ethylendioxy cyclohexyl propionitrile was obtained. The mechanism of the reaction of cyclohexanone with acrylonitrile would be a complicated catalysis process.

关键词： 丙酸   羟基   乳酸酯   农药中间体   不对称合成   除草剂   光学活性   禾本科杂草   防除   用途  

摘要： 用途：R-(+)-对羟基苯氧基丙酸甲脂是重要的农药中间体，尤其被广泛用于合成芳氧苯氧乳酸酯类除草剂，如光学活性农药精吡氟氯禾灵等，该类除草剂是ACCase抑制剂，对于防除禾本科杂草有特效。

关键词： 不对称合成   金属配体催化剂   回收利用   进展  

摘要： 由于不对称合成中所用催化剂多数为金属配体,合成困难且价格昂贵,因此对不对称合成中催化剂的回收与再利用的研究有重大意义,本文对这一研究领域的现状作一概述。

关键词： amino acids   2,5-diketopiperazines   Horner-Emmons reaction   natural products   ylides  

摘要： A new general, short, and efficient strategy for the construction of dehydro-diketopiperazines was developed. Horner-Emmons type coupling between a phosphinyl glycine ester and a formyl heterocycle is the key coupling reaction, which proceeds in good-to-excellent yields on several sterically-hindered substrates. Moreover, racemization of the parent L-amino acids is avoided as a result of the mild basic conditions used. The selection of the NH protective group of the formyl heterocycle was crucial. N-tosylated heterocycles proved ideal for this reaction sequence. Thus, the title compounds, (-)-Phenylhistine and (-)-Aurantiamine, were prepared in high yield (four steps, 47% overall) and optical purity. Furthermore, the synthesis of unnatural derivatives including an indole analogue was successfully completed.

关键词： desymmetrization   Diels-Alder reaction   enzymes   natural products  

摘要： In their pioneering report on the diene synthesis,or the Diels-Alderreaction,Otto Diels and Kurt Alder recognized the profound impact that this pericyclic reactionwould have in the syntheses of"complex compounds related to or identtical with natural products"andspeculated that this process may also be nvolved in the biosyntheses of natural products.

关键词： 手性氨基醇   Reformatsky 反应   烯丙化反应   高烯丙醇   不对称合成  

摘要： 一、手性氨基醇在不对称Reformatsky 反应中的应用 从易得的天然(L)-脯氨酸出发,设计并合成了两类四种手性氨基醇催化剂(1ad), 用于催化不对称Reformatsky 反应,产率48%-73%,e.e.17.4%-74.9%,考察了催化剂用量、反应温度、底物取代基的电子效应等因素对反应的影响。 二、氨基酸促进的四烯丙基锡与羰基化合物加成反应研究 以天冬氨酸为促进试剂,通过烯丙化反应直接制得系列含有三氟甲基的高烯丙醇,产率51.5%-92.6%。研究了底物取代基的电子效应,立体结构等因素对这一反应的影响。 以易得的天然(L)-脯氨酸和(L)-天冬氨酸为原料, 合成两类三种氨基酸衍生物(A,B,C),并以三种氨基酸衍生物为手性促进试剂研究了四烯丙基锡与芳香醛的不对称烯丙化反应,产率73%-93%,e.e.0%-27 %。产物的绝对构型与文献报道的相反。此外,讨论了底物取代基的电子效应等因素对反应的影响。

摘要： The first asymmetric synthesis of an epidithiapiperazinedione (EDPD) was pursued through radical translocation/functionalization of readily available (S)- phenylalanine-derived piperazinediones. Selective abstraction of the hydrogen atoms from the α-C-H bonds of the amino acid derived piperazinedione unit, via a 1,5-hydrogen abstraction, was investigated. Deuterium labeling experiments supported this plan. The project was ultimately abandoned due to the inability to identify captodative radical addition to thiocarbonyl acceptors. In addition, a Pummerer-like process was used to form the key tetracyclic core of dibromophakellstatin and dibromophakellin, small but highly functionalized molecules. The 2-thiophenyl imidazole fragment was built utilizing well-precedented metalation chemistry, with further manipulation furnishing the key intermediate, an imidazole- pyrrole species. The oxidative cyclization was induced by treatment with Stang's reagent (PhICNOTf). The tetracyclic product, isolated in fair yield, was readily hydrolyzed to (±)-dibromophakellstatin. Various attempts to form (±)-dibromophakellin are in progress. The success of the Pummerer process is attributed to its well-defined and unambiguous site of oxidative initiation. Further experimentation toward a model system for the more structurally complex members of this family of sponge metabolites is underway.