关键词： α-sulfinyl carbanion   chiral sulfoxide   conjugate addition   chiral cycloalkanes  

摘要： The reaction of lithiated (R)-2-(trimethylsilyl)ethyl p-tolyl sulfoxide 1 with α,β-unsaturated esters gives 1,4-conjugate addition products as single stereoisomers, whereas the reaction of 1 with 4-, 6-, or 7-haloalkenoates affords cyclopropane-, cyclopentane-or cyclohexanecarboxylates, respectively, with high stereoselectivity.

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： 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： 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.

关键词： 二苯基乙二醇   催化   不对称合成   奎宁定酯   奎宁  

摘要： 利用奎宁和奎宁定酯进行不对称催化合成，得到光学纯１，２－二苯基乙二醇产物，对映体过量（ｅ．ｅ．％）高达９６％以上，该反应条件温和，后处理简便。

关键词： 磷脂   不对称合成   手性前体   甘油型  

摘要： 本文综述了磷脂不对称合成方面的研究进展,包括半合成法和化学合成法。着重讨论了利用不对称反应和手性前体合成不对称甘油型磷脂骨架的方法。