Gold(I)-Catalyzed Synthesis of 3‑Sulfenyl Pyrroles and Indoles by a Regioselective Annulation of Alkynyl Thioethers

The combination of
nucleophilic nitrenoids and π-acid catalysis
has emerged as a powerful tool in heterocycle synthesis. Accessing
more varied heterocycle-substitution patterns by maintaining the same
reaction pathways across different alkynes remains a challenge. Here
we show that Au­(I) catalysis of isoxazole-based nitrenoids with alkynyl
thioethers provides controlled access to (3 + 2) annulation by a regioselective
addition β to the sulfenyl group. The reaction with isoxazole-containing
nitrenoids delivers sulfenylated pyrroles and indoles as single regioisomers
bearing useful functional groups and structural variety.