Nucleophilic Metal Complexes as Acylation Catalysts:  Solvent-Dependent “Switch” Mechanisms Leading to the First Catalyzed Staudinger Reaction

Abstract

[formula: see text] Catalytic acylation using complex transition metal salts MCo(CO)4 is demonstrated. Surprisingly, a solvent-dependent mechanistic "switch" results in a Lewis acid-based acylation mechanism in nonpolar media and a nucleophilic mechanism in polar organic media. These observations lead to the first example of a catalyzed Staudinger reaction to form beta-lactams.