Molecular Iodine-Promoted [3 + 2] Oxidative Cyclization for the Synthesis of Heteroarene-Fused [1,2,4] Thiadiazoles/Selenadiazoles

Two new classes of heteroarene-fused [1,2,4]­thiadiazole and [1,2,4]­selenadiazole are synthesized through the iodine-mediated [3 + 2] oxidative cyclization of 2-aminoheteroarenes and isothiocyanates/isoselenocyanates. This oxidative [3 + 2] annulation strategy is highly regiospecific to proceed a selective C–N bond formation at the endo-nitrogen of 2-aminoheteroarenes followed by an intramolecular oxidative N–S/N–Se bond formation. It is the first example of an I2-mediated oxidative nitrogen–selenium (N–Se) bond formation.

本研究通过碘介导的2-氨基杂芳烃与异硫氰酸酯、异硒氰酸酯的[3+2]氧化环化反应，合成了两类新型杂芳烃稠合[1,2,4]噻二唑（[1,2,4]thiadiazole）和[1,2,4]硒二唑（[1,2,4]selenadiazole）。该氧化型[3+2]环加成策略具有高度区域专一性，可选择性地在2-氨基杂芳烃的内型氮原子处构建C-N键，随后发生分子内氧化N-S/N-Se键合反应。这是首例碘介导的氧化型氮-硒（N-Se）键形成反应。