Diazoacetic ester has been reacted with anthracene, benzanthracene and pyrene. In each case an acid has been obtained by hydrolytic treatment of the reaction mixture. The acid from anthracene has been assigned the structure naphthonorcaradienecarboxylic acid XXV on the basis of hydrogenation experiments and ultra-violet light absorption data. Oxidative degradation has proved the acid from benzanthracene to be benznaphthonorcaradiene-carboxylic acid XXXIV, while the product from pyrene is apparently tribenznorcaradienecarboxylic acid XXXVII. Attention is drawn to the remarkable stability shown by these condensed cyclopropane acids towards attempted rearrangement. An explanation for this is proposed on the grounds of the ability of the cyclopropane ring to conjugate with aromatic centres
