- A new enantiospecific route toward monocarbocyclic terpenoids: Synthesis of (-)- caparrapi oxide
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A new and efficient strategy is described for carrying out the enantiospecific synthesis of monocarbocyclic terpenoids from (-)-sclareol (1). The key steps are the Grob scission of 11-p-toluenesulphonyloxydriman- 7α-ol (2) to give the tobacco seco-sesquiterpene 3 and the Baeyer-Villiger oxidation of 4-[(1'S, 2'S)-2'-formyl-2',6',6'-trimethylcyclohexyl]-2-butanone (4), derived from 3. The first enantiospecific synthesis of (-)-caparrapi oxide (8) based on this methodology is reported.
- Barrero, Alejandro F.,Alvarez-Manzaneda, Enrique J.,Chahboun, Rachid,Paiz, M. Coral
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p. 9543 - 9544
(2007/10/03)
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- 1,3-Diol Fragmentation Using a Reactive Benzylic Hydroxyl Group as a Nucleofuge. Synthesis of a Tobacco Sesquiterpene
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A benzylic hydroxyl group activated by electron-donative aromatic function was found to be a remarkably reactive nucleofuge for 1,3-diol fragmentation.Thus, treatment of α-(2,6-dimethoxy-4-methylphenyl)-2β-hydroxy-2α,5,5,8aβ-tetramethyl-4aα-decahydro-1β-n
- Kato, Michiharu,Tooyama, Youichi,Yoshikoshi, Akira
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- Total Synthesis of (+)-Albicanol and (+)-Albicanyl Acetate via a Highly Diastereoselective Intramolecular Cycloaddition
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The enantioselective total syntheses of the drimane-type sesquiterpenes albicanol (1) and albicanyl acetate (2) starting from (+)-Wieland-Miescher ketone (8) have been accomplished.The key step in the synthetic strategy involves a highly diastereoselective intramolecular dipolar cycloaddition reaction of th nitrile oxide (6), which affords the isoxazoline (5) as the sole product in high yield.Reductive hydrolysis of compound (5) followed by methylenation of the resulting β-hydroxy ketone (4) by application of the Nozaki-Lombardo procedure provides (+)-albicanol (1), which is then converted into (+)-albicanyl acetate (2) by acetylation.The olefinic acetal (15), an intermediate of the present total synthesis, has been transformed by sequential Jones oxidation and methylation into a secosesquiterpene (17), one of the components of sun-cured Greek tabacco.
- Shishido, Kozo,Tokunaga, Yuji,Omachi, Naomi,Hiroya, Kou,Fukumoto, Keiichiro,Kametani, Tetsuji
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p. 2481 - 2486
(2007/10/02)
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- Remarkably Facile 1,3-Diol Fragmentation. Synthesis of a Seco-sesquiterpene of Tobacco
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A benzylic hydroxyl group activated by the 2,6-dimethoxy-4-methylphenyl group was proved to be a remarkably reactive nucleofuge in 1,3-diol fragmentation under mild conditions. 4-(2,2,6-Trimethyl-6-vinylcyclohexyl)-2-butanone, a seco-sesquiterpene, was sy
- Kato, Michiharu,Tooyama, Youichi,Yoshikoshi, Akira
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