Electrophilic Substitution of Anionic Aluminabenzene via Sequential Reactions with Electrophile and Base

The reaction of an isolable anionic aluminabenzene with electrophiles, such as MeOTf and Me3SiOTf, was investigated. The nucleophilic attack on the pentadienyl moiety of the aluminabenzene ring proceeded at the 4-position to form the aluminacyclohexadiene bearing a Me or Me3Si group. Treatment of the resulting methyl- or silyl-substituted aluminacyclohexadiene with the bulky base MesLi gave the rearomatized anionic aluminabenzene bearing a Me or Me3Si group. Thus, this sequential reaction would be considered as an electrophilic substitution of aluminabenzene. The substituent effect of Me and Me3Si groups on the aluminabenzene ring was also estimated on the basis of experimental and theoretical studies.