Electrophilic substitution of two monohomoperylenes and perylene

Various types of electrophilic substitution of monohomoperylene(1)and its 11,11‐difluoro derivative(2)have been studied,viz. Bromination, nitration, acylation, formylation and sulfonation. Bromination withN‐bromosuccinimide (NBS) of1in dichloromethane leads to initial substitution mainly at the α positions 2 and 10,i.e., of the annuleno moiety, followed by further substitution of the β positions 4 and 8 of the same moiety, and of the α positions 2′ and 10′ of the naphthaleno moiety. Reaction of1with 5.0 mol‐equiv. of NBS yields 2,4,8,10,2′‐pentabromo‐1in 46% yield. Sulfonation of1with SO3in dichloromethane using 1.2 mol‐equiv. of dioxane as reactivity moderator leads to the formation of1‐2‐sulfonic acid (1‐2‐S),1‐2,10‐S2, and the intermediate σ complex6. Sulfonation of the 11,11‐difluoro derivative2leads to the formation of2‐2‐S,2‐2,10‐S2and 2‐2,10‐disulfonic anhydride(7), together with small amounts of2‐2,2′‐S2or/and2‐2,10′‐S2. The other types of electrophilic substitution of1and2studied were found to proceed similarly, in that the initial substitution occurs at the 2‐position and the subsequent one at the 10‐position,i.e., perito the primarily introduced substituent. The chemical behaviour (i.e., the substitution pattern and relative reactivity) of the two monohomoperylenes1and2have been compared with that of 1,6‐methano[10]annulene(3), its 11,11‐difluoro derivative(4), and perylene (5). For example, the sulfonation reactivity ratio of the naphthalene to the [10]annuleno moiety is significantly greater for2than1, as predicted on the basis of the higher sulfonation reactivity of3compared to4.