Propargyl Alcohols as β-Oxocarbenoid Precursors for the Ruthenium-Catalyzed Cyclopropanation of Unactivated Olefins by Redox Isomerization

An atom-economical method for the direct synthesis of [3.1.0]- and [4.1.0]-bicyclic frameworks via Ru-catalyzed redox bicycloisomerization of enynols is reported. The presented results highlight the unique reactivity profile of propargyl alcohols, which function as β-oxocarbene precursors, in the presence of a ruthenium(II) complex. Furthermore, a rare case of a formal vinylic C−H insertion reaction is described.