Straining strained molecules. III. The spectral and mutagenic properties and an alternate synthesis of diaceperylene and dicyclopenta[1,2,3-cd:1′,2′,3′-lm]perylene

The synthesis of diaceperylene (1) from 5,6-dilithioacenaphthene via nickel or cobalt catalysed couplings proceeded in better yield than a multistep synthesis involving formation of 5,5′-diacenaphthene first. Dehydrogenation of 1 to dicyclopenta[1,2,3-cd:1′,2′,3′-lm]perylene (2) proved a better route than coupling of 5,6-disubstituted acenaphthylene derivatives. Ultraviolet, proton, and carbon nuclear magnetic resonance spectra and electrode reduction potential data of 1 and 2 are discussed with respect to molecular mechanics calculations of strain in these and related bridged naphthalenes. Both 1 and 2 were found to be weakly mutagenic in an Ames microsome test, in contrast to cyclopenta[cd]pyrene.