Eudesmane and rearranged eudesmane sesquiterpenes from Nectandra cissiflora

Abstract

Four eudesmane-type sesquiterpenes, costic acid (1), 12-carboxyeudesman-3, 11(13)-diene (2), viscic acid (3), 3-oxo-g-costic acid (4) and two rearranged eudesmane derivatives, 3a-hydroxyisoiphion-11(13)-en-12-oic acid (5) and 5b-hydroxy-4-oxo-11(13)-dehydroiphionan-12-oic acid (6), in addition to (-)-epicatechin, have been isolated from the trunk bark of Nectandra cissiflora. This is the first reported occurrence in the Lauraceae of 3-6. The structures of the isolated compounds have been established on the basis of 1D and 2D NMR spectroscopic techniques. The13C NMR assignments of 3, 5 and 6 are given here for the first time, as well as some corrections to the previously reported chemical shift assignments of 4.