Half‐Sandwich (η6‐Benzene)Ruthenium(II) Complex of Picolyl Functionalized N‐Heterocyclic Carbene as an Efficient Catalyst for Thioether Directed C−H Alkenylation of Arenes

In this report, a half‐sandwich (η6‐benzene)Ru(II) complex of picolyl functionalized N‐heterocyclic carbene was synthesized and efficiently used for the alkenylation arenes through thioether directed C−H bond activation. The thioether functionality of the substrate directed a selective ortho‐vinylation through C−H bond activation. Moreover, reaction significantly works under mild reaction conditions than the previously reported ones which use the precious noble metal catalyst including the Pd(II), Rh(III), and Ir(III). Broad substrate scope using several benzyl thioethers and vinyl were found to be well tolerated for the present catalytic reaction to produces moderate to good yields of the desired products. Moreover, it is the first report where a Ru‐based catalyst was used for the alkenylation of thioethers. Picolyl functionalized N‐heterocyclic carbene thioether ligand‐based novel half‐sandwich pincer (η6‐Benzene)Ru(II) complex was synthesized. The prepared Ru(II) complex in presence of Cu(OAc)2 was identified to be an excellent catalyst for O‐alkenylation via CH activation through the S‐directing group. Transformations under mild reaction conditions and tolerance for a wide range of functional groups were observed.