ChemInform Abstract: THE SYNTHESIS OF (+)‐PREMNOLAL

Abstract

Die Synthese der Titelverbindung, Bestandteil von Premna latifolia Roxb.

Approaches to the Synthesis of Aromatic Diterpenes Oxygenated in the A Ring. Synthesis of Margocin

“…Hydrolysis (Me2CO, H2S04) of the epoxide of the latter afforded diol 18 (90%). Ten minutes at 0°with Jones reagent gave the hydroxyketone 19 (83%), and the desired coleon F motif for ring A was finally obtained by dehydrating (SOCl2, pyridine) to the conjugated enone 20. As this route to coleon F appeared laborious, it was abandoned, but the allylic alcohol 10 has been used to synthesize margocin [24], a diterpene recently isolated from Azadirachta indica (16). A more convenient preparation of the exocyclic olefin 3 by One promising route to the gem-dimethyl moiety of margocin involved the cyclopropyl intermediate 21, which was obtained in excellent yield from 10 by a modified Simmons-Smith procedure (19).…”