Synthesis of (±)-thaps-7(15)-ene and (±)-thaps-6-enes

Srikrishna, Adusumilli and Krishnan, Kathiresan (1993) Synthesis of (±)-thaps-7(15)-ene and (±)-thaps-6-enes. In: Perkin Transactions 1 (6). pp. 667-673.

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Abstract

The synthesis of (±)-3a,4,4,7a-tetramethylhydrindan-2-one 8, containing three contiguous quaternary carbons as present in thapsanes, and the total synthesis of thaps-7(15)-ene 6 and thaps-6-ene 7, probable biogenetic precursors of thapsanes, have been achieved. Thus, orthoester Claisen rearrangement of cyclogeraniol 14, followed by hydrolysis of the resultant ester 16 furnished the eneacid 13. Copper sulfate-catalysed intramolecular cyclopropanation of the diazo ketone 18, derived from the acid 13, generated the cyclopropyl ketone 12. Regiospecific reductive cleavage of cyclopropyl ketone 12 furnished the hydrindanone 8, whereas the diazo ketone 26 furnished the hydrindanone 28avia the cyclopropyl ketone 27. Wittig methylenation of the hydrindanone 28a furnished thaps-7(15)-ene 6, which on isomerisation gave thaps-6-ene 7. Allylic oxidation of thaps-6-ene furnished the thapsenone 31, a degradation product of the natural thapsane 1b.

Item Type:	Journal Article
Publication:	Perkin Transactions 1
Publisher:	Royal Society of Chemistry
Additional Information:	Copyright of this article belongs to Royal Society of Chemistry.
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	10 Mar 2011 06:58
Last Modified:	10 Mar 2011 06:58
URI:	http://eprints.iisc.ac.in/id/eprint/35863

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