Iron(II) Complexes for the Efficient Catalytic Asymmetric Transfer Hydrogenation of Ketones

Iron(II) carbonyl compounds of the type trans-[Fe(NCMe)(CO)(P-N-N-P)][BF4](2) bearing the ethylenediamine-derived diiminodiphosphine ligands (R,R)- or (S,S)-1,2-diphenyl-1,2-diaminoethane were synthesized and characterized, including by their crystal Structures. The new complexes are suitable precatalysts For the transfer hydrogenation of ketones Lit room temperature, giving turnover frequencies of up to 2600 h(-1) with low catalyst loadings (0.025-0.17%). Screening experiments showed that the precatalysts arc able to Produce alcohols from a wide range of simple ketones. For sterically demanding prochiral ketones, excellent enantioselectivities were obtained (up to 96% ee).