A new benzannulation reaction and its application in the multiple parallel synthesis of arylnaphthalene lignans

A new aromatic annulation reaction based on sequential Horner–Emmons and Claisen condensation reactions is described. The method is high yielding and provides a rapid entry to arylnaphthalenes. The lignan natural products justicidin B , retrojusticidin B , taiwanin C , justicidin E , chinensin and retrochinensin have all been synthesised in good overall yield using this protocol, demonstrating its potential in multiple parallel synthesis. The selective oxidation of diols to the corresponding retrolactones with barium manganate(VI) is also noteworthy.