Enzyme-Controlled Regiodivergent C–H Amination

Key words

enzyme catalysis - C–H amination - regiodivergency

Significance

Arnold and co-workers report an enzyme-catalyzed asymmetric and regiodivergent C–H amination. By modifying the active site of P411_BM3, a cytochrome P450_BM3 variant in which the axial position of the iron-heme prosthetic group is ligated by serine instead of cysteine, two variants enabling different regioselectivity were obtained. One allowed the selective amination of the energetically more favored benzylic position, while the other was selective for the homobenzylic position of 2,5-disubstituted benzenesulfonyl azides.

Comment

Due to the availability of a weaker benzylic C–H bond, direct C–H amination of homobenzylic positions are a challenge in small-molecule catalysis. Breaking the C–H bond is kinetically controlled, and therefore, this can in some cases be overcome by variation of the steric properties of the used ligands. However, genetically engineered enzymes are an attractive alternative for regiodivergent C–H amination, enabling access to the desired products in good to excellent regio- and enantioselectivities.