The First Palladium-Catalyzed Desulfitative Sonogashira-Type Cross-Coupling of (Hetero)aryl Thioethers with Terminal Alkynes

An unprecedented desulfitative Sonogashira-type cross-coupling protocol is exemplified by the synthesis of substituted 5-chloro-3-alkynylpyrazinones from the corresponding 5-chloro-3-(phenylsulfanyl) pyrazin-2(1H)-ones. The applicability of the method is extended to solid-phase linked pyrazin-2(1H)-ones as well as to some oxazinones, pyrazines, and phenyl thioesters.