Synthesis of chalcones derived from (+)- and (−)-usnic acids

A number of chalcones with the (+)- and (−)-usnic acid moieties were synthesized by the following sequence: the reaction of these acids with phenylhydrazine, reduction of the C(1)=O group with sodium borohydride, O-methylation of the intermediate compounds with diazomethane, and subsequent condensation with substituted benzaldehydes at the acetyl group.