A Selective and Functional Group-Tolerant Ruthenium-Catalyzed Olefin Metathesis/Transfer Hydrogenation Tandem Sequence Using Formic Acid as Hydrogen Source

A ruthenium-catalyzed transfer hydrogenation of olefins utilizing formic acid as a hydrogen donor is described. The application of commercially available alkylidene ruthenium complexes opens access to attractive C(sp3)-C(sp3) bond formation in an olefin metathesis/transfer hydrogenation sequence under tandem catalysis conditions. High chemo-selectivity of the developed methodology provides a remarkable synthetic tool for the reduction of various functionalized alkenes under mild reaction conditions. The developed methodology is applied for the formal synthesis of the drugs pentoxyverine and bencyclane.