Cope rearrangement of some germacrane-type furan sesquiterpenes. Part IV. Preparation of some cyclodeca-cis,trans-diene derivatives and their Cope rearrangements

Abstract

In order to clarify whether the abnormal Cope rearrangement of the cis,trans-cyclodecadienes 6,12-epoxygermacra-3,6,9,11-tetraene (II) and neolonderalactone (6,12-epoxy-8-hydroxygermacra-3,6,9,11-tetraen-14-oic acid γ-lactone)(III) is due to the substituents on the 3,4-and 9,10-double bonds or to the furan ring, the cis,trans-compounds (3Z,9E)-germacra-3,7(11),9-trien-6-one (VII), (3Z,9E)-germacra-3,7(11),9-triene (XI), (3Z,6Z,9E)-11-formylmethylgermacra-3,6,9-triene (XXII), and (6E,10Z)-5,8,9,12-tetrahydrobenzocyclodecene (XXIV) were synthesized. They all underwent a normal Cope rearrangement, thus establishing that the abnormal rearrangement is due neither to the groups on the double bonds nor to the benezene ring.