Tricyclic [10]annulenes. Part 3. Reactions of 7b-methyl-7bH-cyclopent[cd]indene

Abstract

The chemical reactions of the tricyclic [10]annulene (1) are described. The annulene is rapidly hydrogenated to give the fully saturated hydrocarbon (2). It undergoes a substitution reaction with electrophiles and has been nitrated, acetylated, formylated, and sulphonated. The preferential sites of attack of electrophiles are C-5 and C-1. Although the annulene (1) does not undergo cycloaddition reactions with tetra-cyanoethylene, dimethyl acetylenedicarboxylate, or benzyne, it does react with 4-phenyl-1,2,4-triazole-3,5-dione in refluxing 1,2-dimethoxyethane to give the 2:1 adduct (17) and with chlorosulphonyl isocyanate to give the ring-expanded indenoazepine (19). Hydrolysis of (19) gives the amide (20), which shows some antiaromatic character.