Annulation sequences employing methyl (E)- and (Z)-6-iodo-3-trimethylstannyl-2-hexenoates and related bifunctional reagents. Preparation of cisoidcis and cisoidtrans bicyclic dienes
Open Access
- 1 May 1992
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Chemistry
- Vol. 70 (5) , 1385-1396
- https://doi.org/10.1139/v92-177
Abstract
A useful annulation method leading to the stereospecific synthesis of structurally novel, functionalized bicyclic dienes is described. Alkylation of 2-(methoxycarbonyl)cyclopentanone (34) and 2-(methoxycarbonyl)cyclohexanone (35) with methyl (E)- and (Z)-6-iodo-3-trimethylstannyl-2-hexenoates (27, 28) provided the keto diesters 36–39. Conversion of these substances into the corresponding enol triflates 47–50, followed by palladium(0)-catalyzed ring closure of the latter compounds, afforded the bicyclic dienes 55–58. In similar fashion, the keto esters 34 or 35 were transformed into the dienes 59–65. An X-ray crystallographic analysis of the p-nitrobenzoate 69, which was derived from the cisoidcis diene 64, showed that, in 69, the dihedral angle between the two carbon–carbon double bonds is −54.0(5)°.Keywords
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