The 9-aryl-4-oxynaphthofuran-1(3H)-one system is
generally synthesized in two steps from α-aryl-o-toluic
acid derivatives. The method involves a tandem conjugate
addition–Dieckmann type condensation between α-lithiated
α-aryl-o-toluic acid derivatives and
2-furan-2(5H)-one as a key step followed by simple
dehydrogenation or dehydration, and can be applied to the synthesis of
two natural lignans (neojusticidin A and neojusticidin
B).