Scheme 1.

Directed evolution of carbene insertion into the N-H bond by screening of whole-cells^a,b

a) Reaction conditions: BL-21(DE) coexpressing the CYP119 mutants and hug operon, OD₆₀₀ ~25, 0.0025 %mol Ir(Me)-MPIX, N-Me aniline (2.5 μmol), EDA (10 μmol), DMSO (10 μL), M9-N (250 μL), 30 °C, overnight. b) The ee was determined by chiral HPLC and was the average of three reactions; The TON was calculated by the number of substrate molecules converted to the product per iridium cofactor added to the cell culture and was the average of three reactions; ee was used instead of er in this scheme as the measure of enantioselectivity to show more clearly the experimental error in the selectivities.