Iridium(I)-catalyzed Regioselective C-H Activation and Hydrogen Isotope Exchange of Non-aromatic Unsaturated Functionality

Isotopic labelling is a key technology of increasing importance for the investigation of new CH activation and functionalization techniques, as well as in the construction of labelled molecules for use within both organic synthesis and drug discovery. Herein, we report for the first time selective iridium-catalyzed CH activation and hydrogen-isotope exchange at the b-position of unsaturated organic compounds. The use of our highly active [Ir(cod)(IMes)(PPh3)][PF6] (cod=1,5-cyclooctadiene) catalyst, under mild reaction conditions, allows the regioselective b-activation and labelling of a range of a,b-unsaturated compounds with differing steric and electronic properties. This new process delivers high levels of isotope incorporation over short reaction times by using low levels of catalyst loading.