Transformations of podocarpic acid

Abstract

Methyl 12-methoxypodocarpa-8,11,13-trien-16-oate (11) has been converted by two routes into the C13 3'-carboxypropyl derivative (VIII). Friedel-Crafts cyclization of the corresponding acid chloride gave the D-homosteroid (IV). Reformatsky reaction of the 13-succinyl compound gave the lactone (VI); model experiments are also described. The rearrangement of the C12 O-allyl ether gave both the normal C13 allyl phenol (XI) and the coumaran (XIII). Peracid oxidation of (11) gave the expected quinone (XIV) and hydroxy dienone (XV). Photolysis of the unsaturated ketone (XVII) in methanol gave only the corresponding saturated ketone (XXI).