Cycloruthenated primary and secondary amines as efficient catalyst precursors for asymmetric transfer hydrogenation

Ruthenacycles obtained by cyclometalation of enantiopure aromatic primary or secondary amines with [(eta(6)-benzene)RuCl2](2) or with [(eta(6)-pcymene)RuCl2](2) are efficient catalysts for asymmetric transfer hydrogenation (TOF up to 190 h(-1) at room temperature). Enantioselectivities in the transfer hydrogenation of acetophenone ranged from 38% to 89%. It is possible to prepare the catalysts in situ, which allows the use of high throughput experimentation.