Ward, T.R.

ChemCatChem 2014, 6, 1010-1014, 10.1002/cctc.201300825

We report on the optimization of an artificial imine reductase based on the biotin‐streptavidin technology. With the aim of rapidly generating chemical diversity, a novel strategy for the formation and evaluation of biotinylated complexes is disclosed. Tethering the biotin‐anchor to the Cp* moiety leaves three free coordination sites on a d6 metal for the introduction of chemical diversity by coordination of a variety of ligands. To test the concept, 34 bidentate ligands were screened and a selection of the 6 best was tested in the presence of 21 streptavidin (Sav) isoforms for the asymmetric imine reduction by the resulting three legged piano stool complexes. Enantiopure α‐amino amides were identified as promising bidentate ligands: up to 63 % ee and 190 turnovers were obtained in the formation of 1‐phenyl‐1,2,3,4‐tetrahydroisoquinoline with [IrCp*biotin(L‐ThrNH2)Cl]⊂SavWT as a catalyst.