Expanding the Scope of Truce-Smiles Rearrangement: Synthesis of 3-Amino-2-aryl-4 H -benzo[ b ][1,4]thiazine 1,1-Dioxides via Intramolecular C-Arylation

C-Arylation of Ns-(aminophenylsulfonyl)acetonitriles via the Truce–Smiles Rearrangement (TSR) was performed. The reaction plausibly proceeds through the seven-membered spiro-Meisenheimer complex, the intramolecular mechanism of TSR was confirmed by a crossover experiment. Linear intermediates were synthesized in a few steps from readily available building blocks, and C-arylation was followed by acid-mediated cyclization, yielding benzothiazines in a one-pot fashion. The developed method was used to prepare 3-aminobenzothiazine-1,1-dioxides inaccessible by other approaches.