Asymmetric synthesis of both enantiomers of 1,1′-(2′,4-dihydroxy-6,6′-dimethoxy-2,4′-dimethylbiphenyl-3,3′-diyl)bisethanone allows the formal synthesis of both enantiomers of 4,4′,7,7′-tetramethoxy-5,5′-dimethyl-6,8′- bicoumarin (desertorin C).