A mixed Ullmann reaction of methyl 3-iodo-(Xb) and 5-iodo-2, 4-dimethoxybenzoate (XIb) gave dimethyl 2, 4', 6, 6'-tetramethoxy-3, 3'-biphenyldicarboxylate (VI), m.p. 164∼166°. It was proved to be identical with an ester (IIIb) which was derived from matsukazelactone (I). Consequently, matsukaze-lactone was represented by formula (Ic), 7, 7'-dimethoxy-6, 8'-bicoumarin and its biogenesis undoubtedly involves oxidative coupling.