摘要： Effect of the conditions on the enantiomeric purity, overall yield, and isomeric composition of chiral polybromonorbornene Diels-Alder adducts of polybromocyclopentadienes and (-)-menthyl acrylate was studied. Enantiomerically pure polybromonorbornenecarboxylic acids were obtained by resolution of the corresponding racemates through diastereoisomeric salts with l-ephedrine. The structure of the products was confirmed by the IR and H-1 NMR spectra.

关键词： asymmetric Strecker reaction   thermodynamic control   (R)-(-)-2-phenylglycinol chiral auxiliary   potassium [C-14]cyanide   carbon-14 labeled amino acid  

摘要： Five hundred mCi of Potassium [C-14]cyanide at a specific activity of 51 mCi/mmol was used to diastereoselectively introduce the carbon-14 label into 1,6-hexanedial via a thermodynamically controlled asymmetric Strecker reaction using (R)-(-)-2-phenylglycinol as the chiral auxiliary. The expected and predominant (R, S/S, R) diastereomer (2) was separated by preparative normal phase HPLC. The chiral auxiliary was removed by oxidation with lead tetraacetate and the resulting benzylimino nitrile exhaustively hydrolyzed in hydrochloric acid to give (S, S)-2,7-diamino[1,8-C-14(2)]suberic acid (6). Subsequent acylation with di-tert-butyldicarbonate gave the title compound (1) with a radiochemical purity of 95.5%, a specific activity of 113 mCi/mmol, and an enantiomeric purity of 95.5% e.e. To our knowledge this is the first report of the asymmetric Strecker methodology being applied to the synthesis of a carbon-14 labeled amino acid. Copyright (C) 2002 John Wiley Sons, Ltd.

关键词： Chiral auxiliaries   Chiral resolution   Ion pairs   Iron   N ligands  

摘要： Configurational stability is conferred on the complex 1 (R = 4-MeOC6H4) by the carefully designed tetradentate bis(1,10-phenanthroline) ligand. The resolution and asymmetric synthesis of 1 were readily achieved by using tris(tetrachlorobenzenediolato)phosphate(v) anions (2) as chiral auxiliaries. The picture shows the separation of the enantiomers of 1 by preparative ion-pair thin-layer chromatography.

关键词： 不对称合成   环丙烷化反应   非极性溶剂   配合物   氨基酚  

摘要： 手性氨基-羟基化合物是一类用于催化不对称合成和手性辅助合成的重要配体。已经被成功开发的氨基醇配体绝大多数起始于手性源化合物。但是，非手性源的氨基-羟基手性配体的设计和合成已经成为目前不对称合成研究中的一个重要内容和发展趋势。因此，在天然手性源中几乎不存在的、或者不易从天然手性源转化得到的手性氨基酚将是一类重要的研究目标． 本文选择了Betti碱及其手性衍生物为研究目标，完成了Betti碱的拆分、手性配体结构的合成，以及它们在催化不对称合成中的初步应用。 第一章主要解决了Betti碱1的拆分问题．我们发现了外消旋Betti碱1在拆分中发生分解的原因，并开发出一条以丙酮为拆分溶剂的拆分方法，经过对各种条件的优化，在以50克的拆分规模上，Betti碱1的拆分化学收率达到84％，光学收率达到99％ee。 第二章，我们使用手性Betti碱S-1与水杨醛和Cu(Ⅱ)反应，得到相应的双核铜配合物，并用X-射线单晶结构分析确认了手性配合物和外消旋配合物在结构上的差异。并对其催化诱导环丙烷化反应进行了初步的探讨。 最后使用手性Betti碱S-1和它的N-取代衍生物为配体对硼烷还原潜手性酮的反应进行了探讨。虽然未能得到满意的手性诱导结果，但观察到温度对产物立体选择性的显著影响。

摘要： A systematic practical method to prepare highly chi (χ)-constrained amino acids has been developed. It was found that increasing the size of R 1 (see figure) from H to Me to Et to n-Pr led to decreased reactivity of the starting complexes. In the case of R1 as i-Pr, no alkylation was observed. With an increase of the size of R2 from H to Me to Et to i-Bu, the reactivities of the alkyl bromides decreased. The starting Schiff bases had more effective stereocontrol at the α-carbon center than at the β-carbon center. The starting Schiff bases showed differential reactivity toward the racemic electrophile (kinetic resolution). Satisfactory differentiations were obtained at room temperature which makes this method synthetically useful. In the case of R1 as H (NiGlyBPB), the thermodynamically-controlled stereoselectivity of alkylation was as high as 30:1.* A series of dipeptide analogues (TMT-Tic and DMT-Tic) were designed and synthesized to mimic the potent and highly selective δ-opioid receptor pentapeptide ligand-[(2S,3R)TMT1 ]-DPDPE and thus to explore the topographical requirements for recognition of ligands at the opioid receptor through bioassays and NMR studies to facilitate the design of non-peptide compounds to be used as therapeutic agents for pain. (2S,3R)-TMT-L-Tic was found to have best binding affinities at the δ-opioid receptor in TMT-Tic series. In preliminary NMR studies, it was found that these designed peptide ligands have their own distinct conformations in the aqueous media. Meanwhile some modified non-peptide analogues of SL-3111 were prepared to continue our efforts to find effective non-peptide ligands for the δ-opioid receptor. More systematic studies are still ongoing using NMR and computational methods. *Please refer to dissertation for diagram.

关键词： 手性农药   拆分   不对称合成  

摘要： 手性农药是农药化学中一个非常活跃的研究领域.本文介绍了手性农药及其前体拆分、不对称合成的研究进展.

关键词： alkylation   asymmetric synthesis   carbohydrates   chiral auxiliaries   metalation   sulfonates  

摘要： The right choice of sugar auxiliary led to a breakthrough in the first asymmetric α-alkylations of sulfonic acid esters (see scheme). The high asymmetric inductions were reached with 1,2:5,6-di-O-isopropyliden-α-D-allofuranose as the auxiliary group, which can be cleaved off again under mild conditions. Enantiopure α-substituted methyl sulfonates are important building blocks and precursors of bioactive compounds.

关键词： 不对称合成   一元手性季铵盐   二元手性季铵盐   相转移催化剂  

摘要： 利用手性季铵盐做为相转移催化剂进行不对称合成是近年来刚刚发展起来的一种新的不对称合成方法。本文利用廉价易得的手性物质——氯霉素和去氢枞酸为初始原料，合成了几种新的季铵盐类手性相转移催化剂，扩大了手性相转移催化剂的来源，并把它们应用于取代反应和加成反应，以探讨其催化机理和不对称诱导效应。 本论文工作主要包括以下几个方面： 1．综述了近几年来手性季铵盐做相转移催化剂的进展和最新研究成果。 2．以氯霉素为初始原料，经水解、中和、二甲基化、季铵化等反应，合成了两种新型手性一元季铵盐相转移催化剂：PTC-1a和PTC-1b。 3．以去氢枞酸为初始原料，经还原、取代、季铵化等反应，合成了两种新型手性一元季铵盐相转移催化剂：PTC-1c和PTC-1d。 4．以氯霉素为初始原料，经水解、中和、二甲基化、双季铵化等反应，合成了一种新型二元季铵盐相转移催化剂：PTC-2。 5．对合成过程中涉及的手性中间体和产物用1H-NMR、IR、MS、Elemental Anal等进行了系统的表征和分析。 6．应用制得的两类手性季铵盐相转移催化剂催化取代反应和加成反应，以验证其催化效果和不对称诱导效应，并比较它们的异同。 7．依据实验结果和相关原理，探讨PTC-1和PTC-2的不对称诱导效应的机制。

关键词： Lactones - Synthesis   Nuclear magnetic resonance spectroscopy  

关键词： .salen   enantiomeric   asymmetric synthesis   vanadyl   cyanohydrins  

摘要： In has been found that the ionic liquid 1-butyl-3-methylimidazoliumhexafluorophosphate is a good substitute solvent for CH_2Cl_2 to conduct the enantioselectivecyanosilylation of aldehydes to their silylated cyanohydrins, using trimethylsilyl cyanide asreagent and a Schiff base vandayl complex as catalyst. The mass balances (>90%), conversions (>80%)and enantiomeric excess (88% < ee < 90%) were high and comparable to those achieved in CH_2Cl_2. Theionic liquid containing the catalyst can be reused at least four times without loosing activity.