Iminophenol Ligands Derived from Chiral Regioisomeric Hydroxy[2.2]paracyclophane‐carbaldehydes: the Influence of the Substitution Pattern on Asymmetric Induction

Abstract

Abstract The planar‐chiral 12‐hydroxy[2.2]paracyclophane‐4‐carbaldehyde ( 3 , pseudo ‐FHPC) was synthesized and resolved via its Schiff bases 9 using the enantiomers of α‐phenylethylamine. The absolute configurations of the enantiomers of 3 were determined by X‐ray diffraction. Derivatives 7 – 21 , representatives of cyclophane‐derived iminophenols with ortho , pseudo‐gem and pseudo‐ortho arrangement of the functional groups, were prepared and studied as catalysts for the enantioselective addition of diethylzinc to benzaldehyde affording the expected alcohols in up to 97 % ee . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)