TRANSFORMATIONS OF SCLAREOL OXIDE BY BROMINATION - SYNTHESIS OF DRIMAN-8-ALPHA,11-DIOL FROM SCLAREOL OXIDE

Depending on reaction conditions, the reaction of sclareol oxide with N-bromosuccinimide affords either 12-bromo- or 12,16-dibromosclareol o xide, whereas the reaction of sclareol oxide with bromine in methanol gives 12-monobromide or (13S)-11, 12-dibromo-8 alpha,13-epoxy-13-metho xy-14,15-bisnorlabdane. Dehydrobromination of the latter with potassiu m hydroxide in toluene in the presence of polyethylene glycol gives (1 3S)-12-bromo-8 alpha,13-epoxy-13-methoxy-14,15-bisnorlabd-11-ene, ozon olysis of which followed by reduction of the ozonide with LiAlH4 affor ds drimane-8 alpha,11-diol.