Metal‐Free Cross‐Coupling and [4+1] Annulation Reactions of 1,2‐Benzisothiazoles with Nucleophilic Reagents to Construct 2‐CN‐Aryl Thioethers and 3‐Aminobenzo[ <i>b</i> ]Thiophenes

ABSTRACT A straightforward synthesis of 2‐CN‐aryl thioethers and 3‐aminobenzo[b]thiophenes via metal‐free cross‐coupling and [4+1] annulation reactions of 1,2‐benzisothiazoles with indoles or 1,3‐diketones have been developed. Notably, the 1,2‐benzisothiazole was used as a novel bifunctional aryl sulfuration reagent through the cleavage of N─S bond and chlorine atom removal. This reaction tolerated a wide scope of substrates under simple reaction conditions and involved the formation of new aryl C─S and C≡N bonds. In addition, the scale‐up reaction and post‐modification demonstrated the practicability of this protocol.