- Asymmetric Synthesis of Clerodane Diterpenoids: Total Synthesis of (-)-Methyl Kolavenate
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The asymmetric synthesis of (8R,9S,10R)-4,8,9-trimethyl-9-vinyl-Δ4-3-octalone, a versatile intermediate for the syntheses of both trans- and cis-neo-clerodane diterpenoids, has been achieved by extension of Ender's asymmetric alkylation, and its utility is exemplified by the total synthesis of (-)-methyl kolavenate, the first example of a clerodane diterpenoid in optically active form.
- Iio, Hideo,Monden, Mitsugu,Okada, Kimikazu,Tokoroyama, Takashi
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- Theoretical and experimental study of the absolute configuration of helical structure of (2R,3S)-Rubiginone A2 analog
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A novel analogue of (2R,3S)-Rubiginone A2 was synthesized as a chiral helical model compound via an eight-step procedure (2.7% overall yield). Quantum methods, such as density functional theory (DFT) at different basis sets of 6-311+(d), 6-311+
- Zhou, Bei-Dou,Ren, Jie,Liu, Xin-Chun,Zhu, Hua-Jie
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p. 1189 - 1194
(2013/02/25)
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- Determining the absolute configuration of benzopyrenomycin by optical rotation, electronic circular dichroism, and population analysis of different conformations via DFT methods and experiments
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In this work, we have studied the absolute configuration of benzopyrenomycin using different density functional theory (DFT) methods, such as optical rotation (OR), electronic circular dichroism (ECD), and conformation distribution analysis for three kinds of Mosher esters at different levels, e.g., B3LYP/6-31G(d), B3LYP/6-311+G(d), and B3LYP/6-311++G(2d,p) in the gas phase and in solution, respectively. Careful investigations for different chiral Mosher esters using DFT theory exhibited the application conditions for certain chiral molecules in absolute configuration determination. Benzopyrenomycin possesses a unique benzo[a]pyrene-type skeleton and shows strong cytotoxicity against various tumor-cell lines.
- Li, Qing-Ming,Ren, Jie,Zhou, Bei-Dou,Bai, Bing,Liu, Xin-Chun,Wen, Meng-Liang,Zhu, Hua-Jie
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supporting information
p. 3067 - 3074
(2013/03/29)
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- Catalytic enantioselective carbon insertion into the β-vinyl C-H bond of cyclic enones
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Chiral oxazaborolidinium ion-catalyzed Csp2-H functionalization of enones using diazoacetate has been developed. Various β-substituted cyclic enones were synthesized in high yield (up to 99%) with high to excellent enantioselectivity (up to 99%
- Lee, Sung Il,Hwang, Geum-Sook,Ryu, Do Hyun
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supporting information
p. 7126 - 7129
(2013/07/05)
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- Hydrolytic enantioselective protonation of cyclic dienyl esters and a β-diketone with chiral phase-transfer catalysts
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Hydrolytic enantioselective protonation of dienyl esters and a β-diketone catalyzed by phase-transfer catalysts are described. The latter reaction is the first example of an enantio-convergent retro-Claisen condensation. Corresponding various optically active α,β-unsaturated ketones having tertiary chiral centers adjacent to carbonyl groups were obtained in good to excellent yields and enantiomeric ratios (83-99%, up to 97.5:2.5 er).
- Yamamoto, Eiji,Gokuden, Daichi,Nagai, Ayano,Kamachi, Takashi,Yoshizawa, Kazunari,Hamasaki, Akiyuki,Ishida, Tamao,Tokunaga, Makoto
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supporting information
p. 6178 - 6181
(2013/02/25)
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- Improved enantioselective synthesis of natural striatenic acid and its methyl ester
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This letter describes the improved and efficient enantioselective synthesis of natural striatenic acid, isolated from Cheilolejeunea serpentina, and its methyl ester starting from a readily available enantiopure building block.
- Aubin, Yoann,Audran, Gérard,Monti, Honoré
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p. 3669 - 3671
(2007/10/03)
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- Syntheses and absolute configurations of the marine sponge purines (+)-agelasimine-A and (+)-agelasimine-B
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The first total syntheses of (+)-agelasimine-A and (+)-agelasimine-B, adenine-related bicyclic diterpenoids isolated from the marine sponge Agelas mauritiana, have been achieved via a highly stereoselective route. On the basis of the present results, the absolute configurations of both alkaloids have been defined as shown in stereoformulas (+)-1a and (+)-1b, respectively.
- Ohba, Masashi,Iizuka, Kazuaki,Ishibashi, Hiroyuki,Fujii, Tozo
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p. 16977 - 16986
(2007/10/03)
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- Total Synthesis of Dihydrovitamin DHV3 and Dihydrotachysterol DHT3. Application of the Low-Valent Titanium-Induced Reductive Elimination
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Optically active ring A synthons 6, 11, 13, and 14, precursors of DHV3 and DHT3, were synthetized from (-)- and (+)-carvone.Application of the low-valent titanium-induced reductive elimination gave a new synthetic approach to vitamin D3 analogues, as show
- Solladie, Guy,Hutt, Jean
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p. 3560 - 3566
(2007/10/02)
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- Sensitized Photooxygenation of Silyl Enol Ethers of Cyclic Ketones
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α,β-Unsaturated and α-hydroxy ketones are accessible in prototropic ene-reactions with singlet oxygen by sensitized photooxygenation of cyclic silyl enol ethers and subsequent reduction and solvolysis.In a competing silatropic ene-reaction α-silyloxyketones are formed.Formation of different products depends on ring size, configuration and substitution.At C-6 chirally substituted 2-cyclohexenones are synthesized for the first time by sensitized photooxygenation of chiral silyl enol ethers of optically active starting ketones.
- Friedrich, Edgar,Lutz, Werner
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p. 1245 - 1263
(2007/10/02)
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