Synthesis of 2,3,8,9‐Dibenzo‐5,6‐(substituted)benzo‐1,4‐dithio‐7‐oxacyclonona‐2,5,8‐trienes and some electrophilic substitution reactions

Treatment of 5‐(2‐hydroxyaryl)thianthreniumyl perchlorates 1 with sodium hydride in tetrahydrofuran at reflux gave the title compounds 5 in excellent yields. For the reactivities of the compounds 5 , the selected compounds 5 were subjected under the conditions of electrophilic substitution reactions. Bromination of 5,6‐{3‐(2‐butyl)benzo}‐2,3,8,9‐dibenzo‐1,4‐dithio‐7‐oxacyclonona‐2,5,8‐triene ( 5f ) in acetic acid at 60° afforded two bromo compounds 9 (22%) and 10 (69%), which were oxidized by m ‐chloroperbenzoic acid to give tetraoxides 11 (95%) and 12 (97%), respectively. Treatment of 5f with acetyl chloride in the presence of aluminum chloride in carbon disulfide at 0° gave an acetylated compound 13 (58%). Nitration of 5f with nitric acid in acetic acid at 50° gave a nitro compound 17 (15%) together with 1,4‐dioxide 7e (22%) and a 5‐oxide 18 (3%) whose regiochemistry has not been established. On the other hand, 5,6‐(3‐methylbenzo)‐2,3,8,9‐dibenzo‐1,4‐dithio‐7‐oxacyclonona‐2,5,8‐triene ( 5a ) reacted with acetyl chloride under the same conditions to give two acetylated compounds 15 (33%) and 16 (18%). The mechanism for the formation of 5 and the structural elucidation of these compounds are discussed.