Abstract
An account of the development of organoiridiumβcatalyzed hydrogen isotope exchange methods is given for the regioselective labeling of compounds from isotopic hydrogen gas, and their current status. The concept arose out of organometallic chemistry studies of CβH bond activation that revealed the ability of certain metal centers to interact with specific CβH bonds of molecules adjacent to coordinating heteroatoms. Initial success in labeling of model compounds with [Ir(H)~2~(acetone)~2~(PPh~3~)~2~]BF~4~ and deuterium gas provided the stimulus for further investigations into modified catalysts, their use with tritium, and applications to the labeling of a wide variety of more complex compounds. Over time, development of mechanistic models and accumulation of empirical data have grown sufficient to permit the prediction of applicability and regioselectivity based on compound structure. Continuing development of new organoiridium catalysts is broadening the range of compound types that can be labeled. Copyright Β© 2007 John Wiley & Sons, Ltd.