Iron-Catalyzed Synthesis of Benzosultams from N -Phenyl- N -(prop-2-yn-1-yl)benzenesulfonamide and Benzenesulfonyl Hydrazine.

A novel route for an iron-catalyzed tandem sulfonylation, C(sp 2 )-H activation, cyclization reaction which uses N -phenyl- N -(prop-2-yn-1-yl)benzenesulfonamide and benzenesulfonohydrazide to synthesize derivatives of ( Z )-2-phenyl-4-((phenylsulfonyl)methylene)-3,4-dihydro-2 H -benzo[ e ][1,2]thiazine 1,1-dioxide has been developed. The method features convenient operation and good functional group tolerance. In addition, it employs insensitive and inexpensive FeSO 4 as the catalyst and provides a direct approach for the preparation of benzothiazides.