Dual Roles of β‑Oxodithioesters in the Copper-Catalyzed Synthesis of Benzo[<i>e</i>]pyrazolo[1,5‑<i>c</i>][1,3]thiazine Derivatives

Abstract

A facile and efficient method for the chemoselective synthesis of benzo­[<i>e</i>]­pyrazolo­[1,5-<i>c</i>]­[1,3]­thiazine derivatives has been developed by tandem Ullmann coupling reactions of β-oxodithioesters (ODEs) with 3-(2-bromoaryl)-1<i>H</i>-pyrazoles in C–S bond formation manner, in which ODEs play dual roles as both a substrate and a ligand. A series of benzo­[<i>e</i>]­pyrazolo­[1,5-<i>c</i>]­[1,3]­thiazine derivatives were provided in good to excellent yields with CuI as the copper source in the presence of NaOH in CH₃CN at 80 °C under a N₂ atmosphere