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

Highly functionalized 5 H -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.