4-Methoxy and 4-acetoxyhomophthalic anhydrides were prepared by convenient oxidations of homophthalic acid derivatives followed by hydrolysis and dehydrative cyclization. Strong base-induced cycloaddition of these anhydrides to 2-ehloro-6, 6-ethylenedioxy-5, 6, 7, 8- tetrahydro-1, 4-naphthoquinone gave the tetracyclic adducts, which were efficiently converted into 4-demethoxydaunomycinone and daunomycinone.
