Organocatalysis with a Fluorous Tag:  Asymmetric Reduction of Imines with Trichlorosilane Catalyzed by Amino Acid-Derived Formamides^†

Asymmetric reduction of ketimines 1 with trichlorosilane can be catalyzed by N-methylvaline-derived Lewis-basic formamides 3a−d with high enantioselectivity (≤95% ee) and low catalyst loading (1−5 mol %) at room temperature in toluene. Appending a fluorous tag, as in 5a−c, simplifies the isolation procedure, while preserving high enantioselectivity (≤92% ee).