Synthesis of arylnaphthalene lignan scaffold by gold-catalyzed intramolecular sequential electrophilic addition and benzannulation

Abstract

An intramolecular approach to generate compounds containing an arylnaphthalene lignan scaffold in high yields is presented. It involves a sequential intramolecular electrophilic attack of carbonyl on arylalkyne followed by benzannulation catalyzed by gold salt. AuCl 3 in combination with AgSbF 6 works better to effect this transformation. Selected products have been converted into arylnaphthalene lactone natural products such as justicidin E, taiwanin C, and retrojusticidin B (Figure presented). © 2011 American Chemical Society.