Beyond Friedel-Crafts: Spontaneous and Fluoride-Catalyzed Acylation of 2-(Trialkylsilyl)pyridines.

2-(Trialkylsilyl)pyridines react spontaneously with acyl chlorides to give 2-pyridyl ketones in high yields. The process consists of four elementary steps of N-acylation, desilylation, C-acylation, and N-deacylation and results in a selective monosubstitution at the carbonyl group. The key step in this mechanism is the intrinsic generation of a stabilized ylide (Hammick intermediate), which acts as a nucleophile. For the functionalization of complex molecules, an alternative fluoride-catalyzed protocol utilizing more stable acyl fluorides has been developed.