Chemistry of the Podocarpaceae. XXI. Preparation of 3-oxo derivatives of 12-Methoxy-18,19-bisnorpodocarpa-4,8,11,13-tetraene and 18,19-Bisnorabieta-4,8,11,13-tetraene

Abstract

12-Methoxypodocarpa-8,11,13-trien-19-oic acid (11) has been converted into the 3-oxo compound (XX) via the C 3 benzylidene derivative of 12- methoxy-18,19. bisnor-5β-podocarpa-8,11,13-trien-4-one (VIII). The route follows a modification of a sequence used by Zeiss and Martin to convert abieta-8,11,13-trien-18-oic acid (III) into a tricyclic steroid analogue. The latter conversion has been reinvestigated and modified to give a higher yield of 18,19-bisnorabieta-4,8,11,13-tetraen-3-one (XXI).