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1.
The stereoselective total synthesis of (+)-(Z)-laureatin is described. The 3,8-dioxabicyclo[5.1.1]nonane skeleton possessing trans-orientated alkyl substituents at the α,α′-positions to the ether linkage was stereoselectively constructed via formation of the oxetane arising from 4-exo cyclization of hydroxy epoxide existing on the oxocene core. 相似文献
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Karol Michalak 《Tetrahedron letters》2010,51(33):4344-3002
The first total synthesis of (±)-heptemerone G, a diterpenoid metabolite of a submerged culture Coprinus heptemerus, and a new approach to an advanced intermediate for a synthesis of guanacastepene A are reported. 相似文献
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Medium-ring olefinic ketone and lactone enolsilanes were subjected to palladium(II)-mediated cycloalkenylation conditions. Diverse bicyclic ring products were obtained in moderate to good yields. The effect of olefin geometry and ring size is discussed. 相似文献
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The stereoselective total synthesis of (+)-obtusenyne is described. The oxonene skeleton possessing trans-orientated alkyl substituents at the α,α′-positions was stereoselectively constructed via cyclization of the corresponding hydroxy epoxide promoted by Eu(fod)3. 相似文献
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Asymmetric Total Synthesis of Propindilactone G,Part 3: The Final Phase and Completion of the Synthesis
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Xin‐Ting Liang Dr. Lin You Yuan‐He Li Hai‐Xin Yu Prof. Dr. Jia‐Hua Chen Prof. Dr. Zhen Yang 《化学:亚洲杂志》2016,11(9):1425-1435
Two independent synthetic approaches were evaluated for the final phase of the asymmetric total synthesis of propindilactone G ( 1 ). The key steps that led to the completion of the asymmetric total synthesis included: 1) an intermolecular oxidative heterocoupling reaction of enolsilanes to link the core structure to the side chain; 2) an intermolecular Wittig reaction for the formation of the α,β,γ,δ‐unsaturated ester; and 3) a regio‐ and stereoselective OsO4‐catalyzed dihydroxylation of an α,β,γ,δ‐unsaturated enone, followed by an intramolecular lactonization reaction to afford the final product. These reactions enabled the synthesis of (+)‐propindilactone G in only 20 steps. As a consequence of our synthetic studies, the structure of (+)‐propindilactone G has been revised. Furthermore, the direct oxidative coupling strategy for ligation of the core of propindilactone G with its side chain may find application in the syntheses of other natural products and complex molecules. 相似文献
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Estrella Saniger Beatriz Delgado Josefa M. González-Pérez Miguel Á. Gallo Joaquín M. Campos 《Tetrahedron》2004,60(50):11453-11464
The synthesis of (RS)-2- or (RS)-3-methoxy-2,3-dihydro-5H-1,4-benzodioxepins and (RS)-5- or (RS)-3-methoxy-2,3,5,6-tetrahydro-8H-benzo-[1,4,7]-trioxecins has been developed. The mechanism of such a reaction via the boron trifluoride etherate-promoted transformation of 2-(methoxyethoxymethoxy)benzyloxyacetaldehyde dimethyl acetals or 2-(methoxyethoxymethoxymethyl)phenyloxyacetaldehyde dimethyl acetals has been proposed. Transannular versions of the reaction results in the facile ring contraction of 12-membered intermediates to the 10- and to 7-membered benzene-fused O,O-acetals. The characterization of the by-products strongly supports the mechanisms proposed. 相似文献
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Intramolecular (4+3) Cycloadditions of Pyrroles and Application to the Synthesis of the Core of Class II Galbulimima Alkaloids
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Jiayun He Zhihua Chen Wenfei Li Kam‐Hung Low Prof. Dr. Pauline Chiu 《Angewandte Chemie (International ed. in English)》2018,57(19):5253-5256
The first intramolecular (4+3) cycloaddition of pyrroles with epoxy enolsilanes as the electrophiles was developed and used to generate optically‐enriched cycloadducts containing the nortropane substructure in good yields. Using this pyrrole cycloaddition as the key step, we achieved the asymmetric synthesis of a nortropane compound bearing the BCDEF ring structure common to the Class II galbulimima alkaloids. 相似文献
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