Electrophilic Substitution of 3,4-Dihydrocyclopenta[cd]pyrene and the 3-Ketone

Abstract

Abstract Brominaton of 3,4-dihydrocyclopenta[cd]pyrene (1) with bromine yielded predominantly the corresponding 8-bromide; on the other hand, a similar reaction of cyclopenta[cd]pyren-3(4H)-one (2) afforded the 4-bromide. The Friedel–Crafts acetylations 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.