Chemistry of 7-labden-3β,15-diol (I): homochiral synthesis of fregenedadiol

Abstract

7-labden-3β,15-diol was transformed into its diacetyl or dimethoxy derivatives. By double bond isomerization, allylic oxidation and dehydrogenation the diacetyl derivative was transformed into a dienone that was aromatized with good yield by methyl loss to afford 3β,15-diacetoxy-20- nor-5,7,9-labdatrien-7-ol. An analog procedure was used to transform the dimethoxy derivative into 3β,15-dimethoxy-20- nor-5,7,9-labdatrien-7-ol. The triflate of the latter was transformed by a cross-coupling reaction into fregenedadiol dimethyl ether that was demethylated to afford fregenedadiol.