Total synthesis of (±)-picropodophyllone

Abstract

Following model studies, the synthesis of (±)-picropodophyllone was completed by first cyclopropanating the appropriate chalcone (11) with ethoxycarbonyl dimethylsulphonium methylide. Treatment of the resulting cyclopropyl ketone with stannic chloride in either benzene or methylene chloride failed but in nitromethane the tetralone (1Oa) was formed. The lactose ring was completed using formaldehyde with an overall yield based on chalcone of 40%.