关键词： AXIALLY DISSYMMETRIC MOLECULES   ORGANO-ALUMINUM REAGENTS   RHODIUM COMPLEXES   REDUCTION   SILICON   ACETALS   HYDROSILYLATION   CATALYSIS   ADDITIONS   ALDEHYDES  

摘要： Optically active silanes were synthesized by a novel asymmetric synthesis which involved the diastereoselective ring-opening reaction of 1,3-dioxa-2-silacycloheptanes bearing a C-2 chiral auxiliary with Grignard reagents, followed by a lithium aluminum hydride (LiAlH4) reduction. (R)-Ethylmethylphenylsilane and (R)-methylphenylpropylsilane were derived in 93%ee and 98%ee, respectively. The preparation of the other optical silanes is also described. The maximum rotations of some of them have been determined by H-1 NMR and/or capillary GC methods. A mechanism for a diastereoselective ring-opening reaction is proposed based on the stereochemical results.

关键词： D-(-)-樟脑磺内酰胺   (S)(E)-3,7-二甲基-2-辛烯-1,8-二酸   (S)-1-苯甲基甘油  

摘要： 该论文分为三个部分:第一部分:从D-(-)-樟脑磺内酰胺的结构特点上分析,综述了D-(-)-樟脑磺内酰胺在不对称合成九个方面的应用,以D-(+)-樟脑为原料经五步反应合成出D-(-)-樟脑磺内酰胺.第二部分:从昆虫性信息素的特点和应用出发,说明了昆虫性信息素合成的目的和意义.对国内外昆虫性信息素的合成概况,主要从手性信息素的合成方法上进行了综合评述.详细介绍了豆科植物象鼻虫性信息素的主要成分(S)(E)-3,7-二甲基-2-辛烯-1,8-二酸的各种合成方法,借鉴他人之经验,设计了两条不同的合成方法,合成了(E)-6-碘-3-甲基-2-己烯酸乙酯,用D-(-)-樟脑磺内酰胺为手性助剂,合成了目标物,总产率为28.0%,产物经IR、NMR等确证,与其他方法相比,此合成方法线路短,产率高.第三部分:综述了1-苯甲基甘油的外消旋体和(R),(S)型异构体在合成天然产物及药物中的应用,介绍了1-苯甲基甘油及其(R),(S)型异构体的合成方法,该文利用D-(-)-樟脑作为手性拆分剂和α,β-二羟基的保护剂,合成(S)-1-苯甲基甘油,产率为70.0%,光学产率为46.0%e.e.,并对D-(+)-樟脑对α,β-二羟基手性化合物的拆分效果进行了探讨.

关键词： 催化剂诱导   不对称合成   手性化合物   光活物质   手性催化剂  

摘要： 该文利用价廉的樟脑为原料,经高温裂解、酰化等一系列反应,合成了手性β-二酮配体,然后与过渡金属铜络合形成新手性β-二酮铜催化剂,首次应用于不对称环丙烷化反应,得到了很高的%e.e.研究底物结构变化对反应的立体选择性的影响,发现了底物体积增大,产物的化学产率和光学产率均下降;提出了不对称催化可能的反应机理,建立了可能的过渡态立体模型.对两类手性药物进行了化学拆分,首次采用添加手性化学位移试剂HNMR的方法,对拆分化合物的对映体的纯度进行了成功测定,获得了满意的结果.对其它手性配体的合成进行了一些尝试研究,以樟脑为原料,经过高温裂解,酰化等七步不同反应,合成了新的手性β-氨基醇配体,进一步的研究仍在进行中.

关键词： Anions   Aldehydes   Central nervous system   Enantioselective synthesis   Aromatic compounds  

摘要： Enantiomerically pure sulfinimines (thiooxime S-oxides 10), important building blocks in the asymmetric synthesis of amine derivatives, are prepared in good to excellent yields in one step from aromatic, heteroaromatic, and aliphatic aldehydes. This protocol involves treating commercially available (R)-or (S)-menthyl p-toluenesufinate (Andersen reagent 4) with LiHMDS, followed by the aldehyde, affording (E)-10 exclusively. The sulfinimines 10 are formed via a Peterson-type olefination reaction of silylsulfinamide anion 13 with the aldehyde. Anion 13 is generated by reaction of lithium menthoxide (12a) with bis(trimethylsilyl)sulfinamide 11, which is formed in the reaction of 4 with LiHMDS. The other product formed is O-(trimethylsilyl)menthol (12c), which is isolated in >80% yield for recycling. Two other less efficient methods for the asymmetric synthesis of 10 are discussed: (i) the asymmetric oxidation of sulfenimines 6 with chiral nonracemic oxaziridines and (ii) the reaction of metal aldimines, prepared from nitriles, with 4. All of these protocols fail with ketones.

关键词： Mixtures   Hydrocarbons   Adducts   Stereochemistry   Enones  

摘要： Stabilized lithiated sulfoximines 2 and 9 undergo highly diastereoselective Michael reactions with acyclic enones under kinetically controlled conditions. At rt the initially formed anionic Michael adducts undergo intramolecular displacement of the sulfonimidoyl group, with inversion of stereochemistry at the carbon bearing the nucleofuge, to give cyclopropanes. Lithiated sulfoximines derived from S-alkyl sulfoximines give mixtures of 1,2- and 1,4-adducts with enones under kinetically controlled conditions. However, at rt the 1,2-adducts are in equilibrium with their corresponding 1,4-adducts. The 1,4-adducts are formed in a highly diastereoselective manner and are rapidly converted to diastereomerically pure cyclopropanes in good to excellent yields. Optically active versions of these sulfoximines give cyclopropanes in high enantiomeric purities.

关键词： Aldehydes   Organic polymers   Ions   Ethers   Selectivity  

摘要： Treatment of alpha-alkenyl N-Boc oxazolidines with N-bromosuccinimide leads to epoxy oxazolidines via a bromocyclocarbamation reaction which is completely stereoselective. Action of sodium azide an these epoxides, followed by a few functional group manipulations, eventually affords chiral beta-amino alcohols which are intermediates for the enantioselective synthesis of bioactive products: the anti side chain of taxol and a hydroxyethylamine isostere. Both the bromocarbamation cyclization and the nucleophilic cleavage of epoxides are totally regioselective. AM1 calculations suggest that this selectivity is controlled by the positive charge distribution at the electrophilic centers.

关键词： Redox reactions   Oxides   Precursors   Inhibitors   Sulfones  

摘要： The highly diastereoselective DIBALH and DIBALH/ZnBr2 reduction of enantiomerically pure (5S,(S)S)-3-ethoxy-5-(p-tolylsulfinyl)cyclopentenone (9) is used as a key step to the synthesis of oxazolidinone 2, a precursor of glycosidase inhibitor mannostatin. Compound 9 was obtained from 3-ethoxycyclopentenone by direct sulfinylation with (S)-N-benzyl-N-(p-tolylsulfinyl)propionamide.

关键词： 手性化合物   不对称合成   氨基酸   丁酰胺  

摘要： 由L-氨基酸不对称合成了4种新型手性化合物(6a,6b,7a,7b),其结构经IR,~1H NMR,^(13)C NMR及MS等证实。

关键词： 手性药物   对映体   不对称合成   药物开发  

摘要： 开发手性药物将是今后新药开发的又一热点。作者认为，我国应将研究手性制备技术，例如开发实用的不对称合成法、拓宽消旋体拆分思路、进一步发展酶工程技术以及研究无效对映体的转化等列为研究重点。为了能创制具有自主知识产权的手性药物，我国还应加强药物手性与生物活性关系的研究。国家也应在这些方面给予扶持，加大投入，为进行深入、全面的研究创造条件。

关键词： Hydrocarbons   Mixtures   Ethers   Isomerization   Molecular structure  

摘要： The reveromycins A (1) and B (2) are recent examples ofspiroketal-containing natural products isolated from a soilactinomycete belongint to the Streptomyces genus. Both 1 and 2 act asinhibitors of the mitogenic activity Of epidermal growth factor(EGF), while 1 also exhibits Antiproliferative activity against humantumor cell lines KB and K562 as well as antifungal activity. Thegross Structures of 1 and 2 were deduced by spectroscopic Analysis,while the absolute configuration of 1 depicted Followed fromchiroptical and spectroscopic analysis of Various degradationproducts.