Highly Efficient and Practical Hydrogenation of Olefins Catalyzed by in situ Generated Iron Complex Catalysts.

A new method was developed for in situ generation of active Fe catalysts for the hydrogenation of olefins from bench-stable Fe(II) complexes and easily accessible LiAlH4. This method makes the hydrogenation very easy to handle and enables the development of several new Fe catalysts for olefin hydrogenation through practical ligand evaluation. One of the Fe catalysts derived from a Fe complex of a phosphine-bipyridine ligand exhibited unprecedented activity for the hydrogenation of olefins, with turnover numbers up to 10 000 and turnover frequencies up to 37 740 h−1. The NMR studies of the active Fe catalyst showed that a Fe-hydride species stabilized by Al might be a real catalyst.