Metal‐Free and Selective Synthesis of Benzo[ <i>d</i> ]Isothiazol‐3(2 <i>H</i> )‐Ones and Corresponding 1‐Oxides

Abstract Metal‐free and selective synthesis of benzo[ d ]isothiazol‐3(2 H )‐ones and corresponding 1‐oxides has been developed. The use of NCS enables the formation of a diverse range of benzo[ d ]isothiazol‐3(2 H )‐ones from 2‐mercaptobenzamides in excellent yields. Furthermore, this protocol achieves cascade synthesis of the corresponding 1‐oxides by employing excess amounts of NCS or Selectfluor, which facilitates N─S bond formation followed by S═O bond generation. Additionally, mechanistic studies indicate that this strategy may involve disulfide intermediates. Notably, this approach offers a complementary method for accessing both benzo[ d ]isothiazol‐3(2 H )‐ones and their corresponding 1‐oxides.