Some A-ring functionalized kaurenes

Abstract

The preparation of some (-)-kaur-16-enes carrying A-ring functionality analogous to some of the gibberellins is described. Thus kaura-2,16- dienes, chosen as analogues of gibberellin A5, have been derived from the succinate (VII) and the kaurenol (VIII). The succinate has also provided a simple route to (-).kaur-16-ene-3β,19-diol. Intramolecular opening of the 2β,3β-epoxy function by the 19-hydroxyl group provides the oxetane (XXIV) from which (-)-kaur-16-ene-2α,19-diol has been prepared.