N‐Substituted Iminopyridine Arene–Ruthenium Complexes for the Regioselective Catalytic Hydration of Terminal Alkynes

Abstract A series of N‐substituted iminopyridine ligand‐based arene–Ru II complexes with general formula [(η 6 ‐arene)Ru(C 5 H 4 N‐2‐CH=NR)Cl] + was synthesized and characterized by NMR spectroscopy, mass spectrometry, and single‐crystal X‐ray diffraction studies. The synthesized arene–Ru II complexes showed high activity in the regioselective Markovnikov hydration of a range of aromatic and aliphatic terminal alkynes and produced moderate to good yields of the corresponding methyl ketones. Moreover, the Ru II catalysts studied showed good recyclability. The mechanism of the Ru II ‐catalyzed hydration reaction was investigated in detail by performing mass experiments and control experiments, followed by the identification of crucial Ru II –alkyne and Ru II –vinyl organometallic species.