Chemical optimization of artificial metalloenzymes based on the biotin-avidin technology: (<i>S</i>)-selective and solvent-tolerant hydrogenation catalysts <i>via</i> the introduction of chiral amino acid spacers

Incorporation of biotinylated-[rhodium(diphosphine)]+ complexes, with enantiopure amino acid spacers, in streptavidin affords solvent-tolerant and selective artificial metalloenzymes: up to 91% ee (<i>S</i>) in the hydrogenation of <i>N</i>-protected dehydroamino acids.