Mechanistic insights into the base-mediated deuteration of pyridyl phosphonium and ammonium salts.

Pyridines can be deuterated at the remote sites by treatment with KOBu in DMSO- , although without discrimination between the - and -position. Herein, base-catalyzed deuterations have been studied, computationally and experimentally, using a series of pyridyl phosphonium salts with a temporary electron-withdrawing group to block the -position while increasing the acidity in the other positions.