Evaluation of chemical diversity of biotinylated chiral 1,3-diamines as a catalytic moiety in artificial imine reductase

The possibility of obtaining an efficient artificial imine reductase was investigated by introducing a chiral cofactor into artificial metalloenzymes based on biotin-streptavidin technology. In particular, a chiral biotinylated 1,3-diamine ligand in coordination with iridium(III) complex was developed. Optimized chemogenetic studies afforded positive results in the stereoselective reduction of a cyclic imine, the salsolidine precursor, as a standard substrate with access to both enantiomers. Various factors such as pH, temperature, number of binding sites, and steric hindrance of the catalytic moiety have been proved to affect both efficiency and enantioselectivity, underlining the great flexibility of this system in comparison with the achiral system. Computational studies were also performed to explain how the metal configuration, in the proposed system, might affect the observed stereochemical outcome.