Ruthenium-Catalyzed Alkyne Annulations with Substituted 1H-Pyrazoles by C–H/N–H Bond Functionalizations

Cationic ruthenium(II) complexes allowed for highly efficient oxidative annulations of aryl- and alkyl-substituted alkynes by 5-aryl-1H-pyrazoles. The C-H/N-H bond functionalization strategy furthermore proved applicable to the high-yielding activation of heteroaryl as well as alkenyl C-H bonds.