Demonstrating the Chemoselective Lewis Acid Activity of Pyridine(Diimine) Bismuth Cations.

Herein, we describe the preparation of a library of cationic bismuth-(III) pyridine-(diimine) compounds and the assessment of their Lewis acidity measured by their interaction with phosphine oxides, acid halides, and ketones. These bismuth compounds have acceptor number values ranging between that of BiCl3 and AlCl3, however, their catalytic activity for the formation of C-C bonds is distinct from these simple salts. Our studies suggest that Friedel-Crafts-type arene acylation is promoted via acid halide coordination in the presence of similar ketone donors. This work demonstrates that bismuth-(III) pyridine-(diimine) cations serve as selective Lewis acids to achieve C-C bond formation.