Electrophilic Substitution of 3,4-Dihydrocyclopentapyrene and the 3-Ketone

Article abstract of DOI:10.1246/bcsj.66.1248

Bromination of 3,4-dihydrocyclopentapyrene (1) with bromine yielded predominantly the corresponding 8-bromide; on the other hand, a similar reaction of cyclopentapyren-3(4H)-one (2) afforded the 4-bromide.The Friedel-Crafts acetylation of 1 and 2 with acetyl chloride in the presence of aluminum chloride occurred at sites 8, 6, and 1.The isomeric distribution in the acetylation of 1 was similar to that of 2.The relative reactivity of 2 with 1-acetylpyrene in acetylation was 0.75.The partial rate factor of site 1 of 1 was less than that of the corresponding position of 1-acetylpyrene, in spite of the fact that sites 6 and 8 of 1 were more reactive than the corresponding positions of 1-acetylpyrene.Nitration of 2 using acetyl nitrate in acetic anhydride took place at positions similar to the case of the acetylation of 2; however, the nitration of 1 gave the 5-nitro derivative in addition to the 8, 6 and 1-isomers.