3- Oxomanoyl oxide

Some new diterpenoid oxides have been obtained from Eupatorium jhanii. They are jhanol (12) and its 18-acetate together with jhanidiol (13) and its 18-monoacetate and diacetate. Their structures were established by correlation with manoyl oxide and by an examination of their C n.m.r. spectra. 11/3-Hydro-xymanoyl oxide (14) has been isolated from Juniperus oxycedrus ° A group of new 11-oxomanoyl oxide derivatives (15a—e) has been obtained from Coleus forskohlii (Labiatae). Their oxygenation pattern is reminiscent of that of the tricyclic diterpenoids which have beemobtained from other Coleus species. 

The cyclization reactions of manool derivatives have continued to attract attention. A synthesis of the strobane skeleton based on oxymercuration reactions of 13-epimanool has been described. The oxidation of sclareol by chromium salts has been re-examined in a series of papers. The circular dichroism curves of manoyl oxide and its 13-epimers have been examined. Some further 11-oxomanoyl oxide derivatives, coleonol E and F, (13) and (14),... 

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