Second‐Generation N,O‐[2.2]Paracyclophane Ketimine Ligands for the Alkenylzinc Addition to Aliphatic and Aromatic Aldehydes: Scope and Limitations

Second generation N,O‐[2.2]paracyclophane ketimine ligands were investigated for their ability to catalyze the 1,2‐addition of alkenylzinc reagents to aliphatic and aromatic aldehydes with special focus on functionalized substrates. For aliphatic aldehydes, which have always been challenging in this field, remarkably high enantiomeric excesses could be determined (50–95 % ee). However, alkenylzinc reagents bearing heteroatoms proved to be demanding substrates for this system.