A Convenient Enantiospecific Route towards Bioactive Merosesquiterpenes by Cationic-Resin-Promoted Friedel–Crafts Alkylation with α,β-Enones

An enantiospecific route towards bioactive merosesquiterpenes, based on the cationic-resin-promoted Friedel–Crafts alkylation of alkoxyarenes with an α,β-unsaturated ketone, is reported. Reaction of ketone 11 with 3,4-methylenedioxyphenol afforded the corresponding chromene. Treatment of 11 with protected phenol 20 gave aryl nordrimane ketone 21, a suitable intermediate in the synthesis of bioactive merosesquiterpenes and their 8-epi derivatives. By utilizing this methodology, a formal synthesis of (+)-puupehenone and other related metabolites, via triflate 25, is described. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)