Light-Driven gem Hydrogenation: An Orthogonal Entry into Second-Generation Ruthenium Carbene Catalysts for Olefin Metathesis

The newly discovered light-driven gem hydrogenation of alkynes opens an unconventional yet efficient entry into five-coordinate Grubbs-type ruthenium carbene complexes with cis-disposed chloride ligands. Representatives of this class featuring a chelate substructure formed by an iodo-substituted benzylidene unit react with (substituted) 2-isopropoxystyrene to give prototypical second-generation Grubbs-Hoveyda complexes for olefin metathesis. The new approach to this venerable catalyst family is safe and versatile as it uses a triple bond rather than phenyldiazomethane as the ultimate carbene source and does not require any sacrificial phosphines.

Automated summary

The newly discovered light-driven gem hydrogenation of alkynes provides a safe and versatile approach to synthesizing Grubbs-type ruthenium carbene complexes, using a triple bond as the carbene source without needing sacrificial phosphines.