Wieland-Miescher ketone
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The Wieland-Miescher ketone is a bicyclic di-ketone and a starting compound for many natural product syntheses especially because it is available in an enantiomeric pure form. Examples of syntheses performed using this ketone as a starting material are that of ancistrofuran and in the Danishefsky Taxol total synthesis. The original Wieland-Miescher ketone is racemic and prepared in a Robinson annulation of 2-methyl-1,3-cyclohexanedione and methyl vinyl ketone. The intermediate alcohol is not isolated.
The required 2-methyl-1,3-cyclohexanedione can be prepared from resorcinol by hydrogenation over Raney nickel to dihydroresorcinol as the enolate followed by alkylation with methyl iodide.
An enantioselective synthesis employs L-proline as a chiral auxiliary in catalytic amounts . This modification is called the Hajos–Parrish–Eder–Sauer–Wiechert reaction .
[edit] References
- ↑ Wieland, P.; Miescher, K. Helv. Chim. Acta 1950, 33, 2215.
- ↑ Ciceri, Paola, Demnitz, F.W. Joachim, Souza, Márcia C.F. de, Lehmanna, Maik. A Common Approach to the Synthesis of Monocyclofarnesyl Sesquiterpenes. J. Braz. Chem. Soc. 1998, 9, 409-414. ISSN 0103-5053. (Article)
- ↑ 1,6(2H, 7H)-Naphthalenedione, 3,4,8,8a-tetrahydro-8a-methyl-, (S)- Paul Buchschacher, A. Fürst, and J. Gutzwiller Organic Syntheses, Coll. Vol. 7, p.368 (1990); Vol. 63, p.37 (1985). (Article)
- ↑ A. B. Mekler, S. Ramachandran, S. Swaminathan, and Melvin S. Newman Organic Syntheses, Coll. Vol. 5, p.743 (1973); Vol. 41, p.56 (1961). (Article)
- ↑ 1 H-Indene-1,5(6 H)-dione, 2,3,7,7a-tetrahydro-7a-methyl-, (S)- Zoltan G. Hajos and David R. Parrish Organic Syntheses, Coll. Vol. 7, p.363 (1990); Vol. 63, p.26 (1985) Article Identical reaction with 2-methyl-1,3-cyclopentanedione (5 membered ring instead of a 6 membered ring)
