Pheox– and Phebox–aluminum complexes were synthesized and subsequently characterized by spectroscopic analysis. These complexes acted as Lewis acid catalysts, and their catalytic activities were controlled by using the Pheox, Phebox, and heteroatom ligands. The Pheox–aluminum complex exhibited an opposite substrate selectivity to AlCl3 in a competitive hetero‐Diels–Alder reaction between electron‐rich and electron‐deficient aldehydes.

Novel organoaluminum catalysts, 2‐oxazolinylphenylaluminum (Pheox‐Al) and 2,6‐bis(oxazolinyl)phenylaluminum (Phebox‐Al) complexes, were synthesized. Their important properties such as Lewis acidity, catalytic activity, and substrate recognition can be controlled by hydrocarbyl ligands. Phebox‐Al(OTf)2 had a much higher catalytic activity than typical inorganic Al salts such as AlCl3 and Al(OTf)3 in hydroboration of aldehydes. Furthermore, Pheox‐AlCl2 exhibited an opposite substrate selectivity to AlCl3 in a competitive hetero‐Diels–Alder reaction. More information can be found in the Communication by Y. Nishimoto, M. Yasuda, et al. on page 10792.