Fourth International Electronic Conference on Synthetic Organic Chemistry (ECSOC-4), www.mdpi.org/ecsoc-4.htm, September 1-30, 2000

[C0007]

.	.

Yvain Roué, Anne-Claire Hervier, Francois-Didier Boyer, Paul-Henri Ducrot* Unité de Phytopharmacie et Médiateurs Chimiques, INRA, Route de Saint-Cyr F-78026 Versailles Cedex, France Fax 01 30 83 31 19 E-mail [email protected] Received: 26 July 2000 / Uploaded: 9 August

Introduction :

Clerodanes diterpenes have been considerably studied by biologists and chemists, according to their interesting antifeedant activity on insects as well as their unique structure, which make them a challenging target for total synthesis. Several problems related to their synthesis have been solved1,2,3, and some natural products have been synthesised in the ajugarin's series4 as well as in the dehydroclerodanes 4c. However, the problem of the stereoselective construction of the acyclic C-9-C-115 double bond, drastically related to this of the stereochemical control of stereogenic centers C-8, C-10 and C-5 remains up to date.
We have developped two stategies aimed to this goal. Both strategies consist in controlling  the configurations of some of the stereogenic centers of the target molecule in an early bicyclic structure easy accessible. One of the ring of these precursors should prefigurate the B ring of the clerodanes, the cleavage of the other ring giving access to functionnalized side chains which should allow the further elaboration of either the decalinic moeity of the molecule or the furofuran system through well known methodologies.
 

route A retrosynthesis route B retrosynthesis

Route B allows a rapid control of the configurations at C-9 and C-11 but needs a further elaboration of ring B of the clerodin, and especially the introduction of a methyl group at C-8 and the construction of ring A. Results obtained have already been published (Ducrot, P.-H.; Hervier, A.-C.; Lallemand, J.-Y. Synth. Comm. 1996, 26, 4447-4457).
This poster describes results obtained in route A, where the configurations at C-8, C-9 and C-10 are easily controlled.

Results :
 

• Route B : summary of published results

• Route A :  preparation of the synthon and ring B elaboration

• Route A : upper ring enlargment

• Route A : optical resolution of a key intermediate

• Route A : alternative to the ring enlargment

All comments on this poster should be sent by e-mail to (mailto:[email protected] ona.edu) [email protected] with C0007 as the message subject of your e-mail.