Chemistry of 7-labden-3β,15-diol (I): homochiral synthesis of fregenedadiol
摘要:
7-labden-3beta,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 3beta,15-diacetoxy-20-nor-5,7,9-labdatrien-7-ol. An analog procedure was used to transform the dimethoxy derivative into 3beta,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.
Side-chain migration reactions and ring B aromatization in labdanes: scope and limitations. Synthesis of isofregenedane type tetrahydronaphthalenic diterpenes
The reaction of bicyclicditerpenes with an allylic oxygenated function or an equivalent functionality on ring B in the presence of I2/benzene afforded a simple and rapid synthesis of tetrahydronaphthalenic diterpenes of the isofregenedane class.