关键词： 番荔枝内酯   目标化合物  

摘要： 该论文以天然番荔枝内酯Bullatacin为母体化合物,将其中双四氢呋喃环片简化为乙二醇二醚片段,并且改变了C(15)构型,得到目标化合物,并成功地进行了合成.在该小组研究番荔枝内酯全合成经验的基础上,从L-(+)-乳酸乙酯出发,经由aldol缩合、关环、DBU消除等关键步骤,构筑了手性γ-丁内酯片段;由D-mannitol出发,通过高磺酸钠氧化断裂、Wittig反应、氟化铯(CsF)催化成醚等反应步骤合成左边片段;再从辛二炔出发,在BF<,3>·Et<,2>O存在下,以炔负离子区域选择性开环氧,分别连接左边长碳链和右边内酯环,从而巧妙地完成了骨架的构建.

关键词： ENANTIOSELECTIVE SYNTHESIS   TRANS-DECAHYDROQUINOLINES   CIS-DECAHYDROQUINOLINES  

摘要： An efficient asymmetric synthesis in nine steps of natural (-)-pumiliotoxin C (1), a decahydroquinoline alkaloid found in the skin of Central American frog species, is presented. The enantiomerically pure starting material (S)-norvalinol(3), obtained from commercial (S)-norvaline, was cyclized in a one-pot procedure to the tosylated aziridine 5. Ring opening with propargylmagnesium bromide led to the acetylenic sulfonamide tosylamide 6, free of the allenic isomer. Compound 6 was methylated on the acetylenic C-atom, reduced, and deprotected with Na in liquid NH;to give the (E)-configured unsaturated amine 8, which was condensed with crotonaldehyde to the imine 9 and N-acylated with isobutanoyl chloride to the key intermediate 2. Intramolecular Dic ls-Alder reaction furnished a diastereoisomeric mixture of N-protected octahydroquinolines 10. After catalytic hydrogenation and cleavage of the amide, natural 1 was obtained as the main product in 25% overall yield;3.2% of its isomer 11 with the inverse configurations in position 4a, 5, and Sa was also isolated.

关键词： PYRROLIDINE   BIOSYNTHESIS   PHOSGENE   CHLORIDES  

摘要： The preparation of (R)-2[(pyrrolidin-1-yl)methyl] pyrrolidine and (R)-1-methyl-2-[(pyrrolidin-1-yl)methyl]pyrrolidine (both in 85% ee) is reported. The key step in the synthesis involves the sparteine-mediated asymmetric functionalization of N-Boc pyrrolidine and subsequent trapping with 1-pyrrolidine-carbonyl chloride.

关键词： BIOSYNTHESIS   ASYMMETRY (Chemistry)  

摘要： A facile and efficient asymmetric synthesis of 7-epi-gamma -eudesmanol described. (1) starting from (-)-dihydrocarvone is described.

关键词： ASYMMETRY (Chemistry)   CHEMICAL reactions   ENANTIOMERS  

摘要： We describe herein a method providing access to both enantiomers of 3-acetylthio-2-benzylpropionic acid via enzymatic desymmetrization of 2-benzyl-1,3-propanediol. These compounds are respectively the starting materials for the synthesis of ecadotril, and dexecadotril, which are powerful inhibitors of NEP (EC 3.***.24.11) and have been developed as therapeutic agents.

摘要： Bisbenzyltetrahydroisoquinoline (BBIQ) alkaloids are a very large and structurally diverse family of compounds that have been isolated from a variety of plant sources and have been found to exhibit a multitude of pharmacological properties including antitumor, antimalarial, and antibacterial activities. Variations in the number of aromatic oxygen substituents present, the number of ether linkages, the nature of the ether bridges and the sites on the two benzylisoquinoline units where the ether or carbon-carbon bond originate, have made BBIQs very interesting targets for several synthetic endeavours. -- The research described herein will focus on the anti-inflammatory and antioxidant activities of the BBIQ oxyacanthine and several other compounds isolated from the herbal plant Mahonia aquifolium using the lipoxygenase inhibition and DPPH radical scavenging assays. In addition, the total synthesis of two target BBIQ are investigated utilizing the Pictet-Spengler and Bischler-Napieralski strategies for isoquinoline formation. Furthermore, alternative means to the classic Ullmann conditions for ether linkages is explored.

关键词： 2，3－二氢－1H-异吲哚－1－酮   邻苯二甲酸酐   不对称合成   （R）－（－）－苯基甘氨醇   邻苯二甲酰亚胺   还原烷基化   [1，3]噁唑并－异吲哚－5－酮   手性辅助剂  

摘要： 3-烷基-2，3-二氢-1H-异吲哚-1-酮（Ⅰ）类化合物存在于许多天然有机物和生理活性物质的核心结构中，具有广阔的医学和生化应用前景。此外，这类化合物还可作为不对称合成的手性辅助剂，还原后可作为手性配体，在不对称合成中具有潜在的应用前景。 本论文的目的是在本实验室以往研究工作的基础上，开发手性异吲哚酮合成子的合成路线，建立一种灵活多用的合成方法，以期为不对称合成提供新型手性辅助剂，用于不对称合成反应。 首先，从邻苯二甲酸酐（Ⅱ）和（R）-（-）-苯基甘氨醇（Ⅲ）出发，合成了N-取代邻苯二甲酰亚胺（Ⅴ）。把Ⅴ的羟基用苄基保护后的产物Ⅵ进行还原烷基化反应，即格氏试剂加成—三氟化硼合乙醚催化下的三乙基硅烷还原去羟基反应，应用甲基格氏试剂可得到一对非对映异构体Ⅷ，两异构体比例约为3:2，但R_f值相同，无法用常规方法分开。幸运的是，直接对Ⅴ进行还原烷基化反应，结果得到了可用柱层析法分离的一对非对映异构体Ⅸ。与文献的方法对比，我们的方法具有灵活多用的优点，可用格氏试剂方便地引入侧链，现已引入甲基、乙基、丁基、异丁基、庚基、苯基、苄基等多种基团，加成反应产率一般可达到96％，还原反应产率一般大于85％，d.e.值在42％到82％之间。并经X-射线单晶衍射测定，证实了主产物为（1′R）-（3R）构型。 其次，将Ⅶ环化制得Ⅹ，再在四氯化钛催化下用三乙基硅烷还原，可以以较高的立体选择性得到Ⅸ，当R为甲基时d.e.值90％，产率66％。此外，用价廉易得的亚苄基酞Ⅳ代替Ⅱ作为原料与Ⅲ缩合，环化后还原，可以得到侧链R为苄基的产物Ⅸ（d.e.值84％，产率98％）。 最后，对化合物Ⅸ的去除手性辅助基进行了初步研究，用先消除成烯再 断C—N键的方法，可以得到具有光学活性的3－取代2，3－二氢－IH－异吼跺－ 卜酮U＊为异丁基)，e上．值为69％。尽管观察到发生了一定的外消旋化，但也 为制备异吼跺酮合成子互积累了一些经验。

关键词： d-生物素   维生素H   不对称合成   格氏反应   立体专一性氢化  

摘要： 该文研究了以工业化生产d-生物素为目的的[C<,4>+C<,1>]的合成路线的设计,完成了d-生物素的全合成,取得了一系列具有学术意义和应用前景的结果.此外,在该章对相关反应进行了研究,确证了格氏反应的副产物12的立体结构.所合成的化合物均经IR、NMR和MS表征,其中化合物12和化合物2的绝对立体结构经X-单晶衍射确证.

关键词： Hydrocarbons  

摘要： Enantiomerically pure (+)-(1S4S,5S 6S)-6-endo-(benzyloxy)-5-exo-{[(tert-butyl)dimethylsilyl]oxy}-7-oxa-bicyclo[2.2.1]heptan-2-one ((+)-5) and its enantiomer (-)-5, obtained readily from the Diets-Alder addition of furan to 1-cyanovinyl acetate. can be converted with high stereoselectivity into 8-oxabicyclo[3.2.1]octane-2,3.4.6,7-pentol derivatives (see 23- 28 in Scheme 2). A precursor of them, (1R,2S,4R,5S,6S,7R,8R)-7-endo-(benzyloxy)-8-exo-hydroxy-3,9-dioxatricyclo[4.***.1.0(2.4)]non-.5-endo-yl benzoate ((-)-19), is transformed into (1R,2R,5S, 6S,7R,8S)-6-exo,8-endo-bis(acetyloxy)-2-endo-(benzyloxy)-4-oxo-3,9-dioxabicyclo[3,3.1]non-7-endo-yl benzoate ((-)-43) (see Scheme 5). The latter is the precursor of several protected 2,6-anhydrohepturonic acid derivatives such as the diethyl dithioacetal (-)-57 of methyl 3,5-di-O-acetyl-2,6-anhydro-4-O-benzoyl-D-glycero-D-galactohepturonate (see Schemes 7 and 8). Hydrolysis of (-)-57 provides methyl 3,5-di-O-acetyl-2,6-anhydro-4-O-benzoyl-D-glycero-D-galacto-hepturonate 48 that undergoes highly diastereoselective Nozaki-Oshima condensation with the aluminium enolate resulting from the conjugate addition of Me2AlSPh to (1S,5S,6S,7S)-7-endo..]oxy}-8-oxabicyclo[3.2,1]oct-3-en-2-one ((-)-13) derived from (benzyloxy)-6-exo-1[ (tert-butyl)dimethylsityl]oxy}-8-oxabicyclo[3.2.1]oct-3-en-2-one (( (+)-5 (Scheme 12). This generates a beta -C-mannopyranoside, i.e., methyl (7S)-3,5- di-O- acetyl-2,6-anhydro-4-O-benzoyl-7-C-[(1R,2S,3R,4S,5R,6S,7R)-6-endo-(benzyloxy)-7-exo-{[(tert-butyl)dimethylsilyl]oxy}-4-endo-hydroxy-2- exo-(phenylthio)-8-oxabicyclo[3.2.1]oct-3-endo-yl-L-glycero -D-manno-heptonate ((-)-70 see Scheme12), that is converted into the diethyl dithioacetal (-)-75 of methyl 3-O-acetyl-2.6-anhydro-4,5-dideoxy-4-C-{[methyl (7S)-3,5,7- tri- O -acetyl-2,6-anhydro-4- O -benzoyl-L -glycero-D-manno- heptonate] -7- C-yl] -5- C- (phenylsulfonyl)-L-glycero-D-galacto-hepturonate (76 see Scheme 13). Repeating the Nozaki-Oshima condensation t

关键词： asymmetric catalysis   asymmetric synthesis   natural products   palladium   total synthesis  

摘要： The power of Pd-catalyzed asymmetric allylic alkylation (AAA) reactions is clearly demonstrated by the efficient synthesis of the complex title compound 1, an analogue of hygromycin A. The modular nature of the synthetic route is ideally suited to provide access to further analogues.