Synthesis, Isolation, Characterization, and Reactivity of High-Energy Stereogenic-at-Ru Carbenes: Stereochemical Inversion through Olefin Metathesis and Other Pathways

The synthesis, isolation, purification (routine silica gel chromatography), and spectroscopic characterization of high-energy endo stereogenic-at-Ru complex isomers, generated by ring-opening/cross-metathesis (ROCM) reaction of the corresponding exo carbenes, are disclosed. We provide experimental evidence showing that an endo isomer can undergo thermal or Brønsted acid-catalyzed polytopal rearrangement, causing conversion to the energetically favored exo carbene.