Copper Complexes with Protein-Based N-Donor Ligands as cis-Selective Nascent Cyclopropanases

Abstract

In this study, we aimed to develop protein-based metal ligands to catalyze cis-selective cyclopropanation using the TM1459 cupin protein superfamily. Copper complexes with TM1459 mutants containing the 3-His metal-binding site exhibited excellent diastereoselectivity in cyclopropanation reactions with styrene and ethyl diazoacetate. Further mutations in the secondary coordination sphere increased the cis-preference with t-butyl diazoacetate as the substrate with up to 80 : 20 (cis:trans ratio) and high enantioselectivity (90 % ee).

Keywords: Artificial metalloenzymes; Cupin; Cyclopropanation; Metallocarbene; Mononuclear copper enzyme.