The fungus Verticillium lamellicola affords lamellicolic anhydride 1 (5-methyl-2, 4.7- trihydroxy-1, 8-naphthalic anhydride) together with small amounts of the quinone 2, the carbonate 3 and the chloro compound 4. Selective reactions of the functional groups in these and their derivatives have been used to interrelate these and effect conversion of 1 into 18, the anhydride obtained from Penicillium herquei.