BF3-Catalyzed Cycloadditions of Naturally Occuring Sesquiterpene p-Benzoquinones

Article abstract of DOI:10.1021/jo00381a010

Lewis acid catalyzed reactions of all known naturally occurring perezone analogues and two allylic alcohols prepared from perezone and hydroxyperezone show that these p-benzoquinones exhibit a complex behavior upon acid treatment.As in the case of perezone, O-angeloylperezone and 6-angeloxyperezone afforded pipitzol analogues.Hydroxyperezone and O-angeloyl-6-hydroxyperezone yielded a stable boron adduct of perezinone.Curcuquinone, the simplest sesquiterpene quinone, afforded mainly polymeric material, while 15-hydroxyperezone and hydroxyperezone derivatives gave a dibenzofurandione and a tricyclic molecule containing a new skeleton, respectively.The results for O-angeloylperezone, compared with those of perezone, show that steric effects play an important role in these transformation allowing at present complete stereocontrol of the reaction outcome.