An Artificial Metalloenzyme Based on a Copper Heteroscorpionate Enables sp(3) C-H Functionalization via Intramolecular Carbene Insertion

The selective functionalization of sp(3) C-H bonds is a versatile tool for the diversification of organic compounds. Combining attractive features of homogeneous and enzymatic catalysts, artificial metalloenzymes offer an ideal means to selectively modify these inert motifs. Herein, we report on a copper(I) heteroscorpionate complex embedded within streptavidin that catalyzes the intramolecular insertion of a carbene into sp(3) C-H bonds. Target residues for genetic optimization of the artificial metalloenzyme were identified by quantum mechanics/molecular mechanics simulations. Double-saturation mutagenesis yielded detailed insight on the contribution of individual amino acids on the activity and the selectivity of the artificial metalloenzyme. Mutagenesis at a third position afforded a set of artificial metalloenzymes that catalyze the enantio- and regioselective formation of beta- and gamma-lactams with high turnovers and promising enantioselectivities.