Synthesis of Hetero‐annulated Dibenzothiophene Analogues via ZnBr ₂ ‐Mediated Domino Reaction of 2/3‐Bromomethylbenzo[ b ] Thiophene With Heteroarenes

The domino reaction of 2‐acetyl 3‐bromomethyl benzo[ b ]thiophene with heteroarenes in the presence of ZnBr 2 in 1,2‐DCE at room temperature furnished various types of hetero‐annulated dibenzothiophenes. The similar annulation reaction of 2/3‐bromomethyl benzo[ b ]thiophene containing MVK unit with heteroarenes in 1,2‐DCE at 80°C afforded corresponding hetero‐annulated compounds. The ZnBr 2 ‐mediated domino reaction could be successfully performed with a wide variety of thiophenes, benzo[ b ]thiophenes and representative benzo‐heterocycles such as indole and benzo[ b ]furan to afford the respective annulated hetero acenes in moderate yields.