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Enantiospecific formal total synthesis of homogynolide-A

Srikrishna, A and Reddy, Jagadeeswar T (2001) Enantiospecific formal total synthesis of homogynolide-A. In: ARKIVOC: Online Journal of Organic Chemistry, 2 (10). pp. 9-19.

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Abstract

Formal total synthesis of both enantiomers of homogynolide-A, a sesquiterpene containing an alpha -spiro-beta -methylene-gamma -butyrolactone moiety fused to a bicyclo[4.3.0]nonane framework, is described. Thus, (R)-carvone was converted into both enantiomers of 3-methylcarvone 14. A reductive allylation, Wacker oxidation and intramolecular aldol condensation sequence transformed 3-methylcarvone into the hydrindanone 18. Regiospecific reduction of the enone followed by a three step degradation of the isopropenyl group converted the hydrindanone 18 into the dione 21, which on regioselective ketalisation furnished the key intermediate ketoketal 13. Methoxymethylene Wittig reaction followed by bromoacetalisation reaction transformed the ketoketal 13 into the bromoacetal 23. The 5-exo-dig radical cyclisation of the bromoacetal 23 followed by the hydrolysis and oxidation of the resultant spiroacetal 24 furnished a 1:4 mixture of the Greene's precursor ketospirolactone 12 and its spiroepimer 26.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Arkat-USA, Inc.
Keywords: Homogynolide-A,reductive allylation,Wacker oxidation,intramolecular aldol condensation,Wittig reaction.
Department/Centre: Division of Chemical Sciences > Organic Chemistry
Date Deposited: 03 Jun 2009 06:13
Last Modified: 19 Sep 2010 04:54
URI: http://eprints.iisc.ernet.in/id/eprint/16887

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