Enantioselective Organozinc Addition to Aldehydes Using Planar Chiral [2.2]Paracyclophane‐Imidazoline N,O‐Ligands

We present an improved and convenient synthesis of [2.2]paracyclophane‐imidazoline N,O‐ligands with central and planar chirality in seven steps starting from [2.2]paracyclophane. The utility of these ligands in organozinc additions to aldehydes is described. The asymmetric ethylation of aldehydes proceeded with enantioselectivities of up to 97 % ee, while the asymmetric arylation of aldehydes gave up to 95 % ee (R) and 82 % ee (S) using (S,S,SP)‐UCD‐Imphanol and (S,S,RP)‐UCD‐Imphanol, respectively. A convenient synthesis of planar chiral [2.2]paracyclophane imidazoline N,O‐ligands has been developed. The application of these classes of ligands showed excellent performance in organozinc additions to aldehydes. An improved seven‐step synthesis of [2.2]paracyclophane‐imidazoline N,O‐ligands (UCD‐Imphanols) possessing both central and planar chirality is presented. These ligands are applied in organozinc additions to aldehydes, achieving enantioselectivities of up to 97 % ee in ethylation and 95 % ee (R) and 82 % ee (S) in arylation using (S,S,SP)‐ and (S,S,RP)‐UCD‐Imphanols, respectively.