Novel enantioselective photocatalysis by chiral, helical ruthenium(II) complexes

Abstract

The enantioselective photoreduction of the helical substrates of rac-[Co(acac)₃](acac ^–= acetylacetonato) and rac-[Co(edta)]^–(edta^4–= ethylenediaminetetraacetato) with the newly synthesized helical photocatalysts Δ-(or rac)-[Ru[Menbpy)₃²⁺{Menbpy = 4,4′-bis[(1R,2S,5R)-(–)-menthoxycarbonyl]-2,2′-bipyridine}, and Λ-(or Δ)-[Ru{(S or R)-PhEtbpy}₃]²⁺{(S or R)-PhEtbpy = 4,4′-bis[(S)-(–) or (R)-(+)-1-phenylethylaminocarbonyl]-2,2′-bipyridine} was realized in the helical-shape recognition reaction with a maximum enantiomer rate ratio (K^Δ;/K^Λ) of 14.7 in 90%v/v EtOH-H₂O at 25 °C.