Exploring the Limits of π‐Acid Catalysis Using Strongly Electrophilic Main Group Metal Complexes: The Case of Zinc and Aluminium

Abstract

The catalytic activity of cationic NHC-Zn^II and NHC-Al^III (NHC=N-heterocyclic carbene) complexes in reactions that require the electrophilic activation of soft C-C π bonds has been studied. The former proved able to act as a soft π-Lewis acid in a variety of transformations. The benefit of the bulky IPr NHC ligand was demonstrated by comparison with simple ZnX₂ salts. The tested NHC-Al^III catalyst is not able to activate C-C π bonds but simple AlX₂ ⁺ ions were found potent in some cases.