Gold-Catalyzed [3,3]-Sigmatropic Rearrangement of ortho-Alkynyl‑S,S‑diarylsulfilimines

Highly functionalized 5H-pyrrolo[2,3-b]pyrazine cores, carrying a diaryl sulfide moiety at the C-7 position, were obtained from a gold-catalyzed reaction using easily accessible ortho-alkynyl-substituted S,S-diarylsulfilimines as intramolecular nitrene transfer reagents for the first time. The reaction proceeds under mild conditions, providing excellent yields while tolerating a large variety of different substitution patterns. We provide experimental evidence for an intramolecular reaction mechanism, likely including an unprecedented gold-catalyzed amino sulfonium [3,3]-sigmatropic rearrangement.