A novel oxidative cleavage of the steroidal skeleton

With the objective of preparing higher oxygenated cephalostatin analogues a nd probing the importance of the Delta(14, 15)-double bond for biological a ctivity we investigated the syn-dihydroxylation of homoallylic alcohol 3. W hilst this reaction took place with the expected P-diastereoselectivity usi ng RuCl3/NaIO4 to provide glycol 10, we noticed that under more forcing con ditions an oxidative cleavage occurred to yield the unusual bisketal 12. Th is interesting transformation was applied to bissteroidal pyrazines to affo rd the highly oxygenated cephalostatin analogues 24-26. Preliminary test re sults with these compounds indicated, however, a lack of cytostatic activit y.