Gold-Catalyzed Nitrene Transfer to Activated Alkynes: Formation of α,β-Unsaturated Amidines

A gold-catalyzed intermolecular nitrene transfer to alkynes was developed for the first time, revealing a new mode of nitrene transfer and providing a novel access to versatile α-imino metal carbenes. Various mild nitrene-transfer reagents were examined, and iminopyridium ylides especially those based on 3,5-dichloropyridine proved be highly effective. With activated alkynes such as N-alkynyloxazolidinones as substrates, α,β-unsaturated amidines were formed in mostly good yields.