Deuterium exchange labelling of substituted aromatics using [IrH₂(Me₂CO)₂(PPh₃)₂]BF₄

Deuterium exchange labelling experimets were conducted on several series of compounds, including para ‐substituted benzoate esters, para ‐substituted N,N‐dimethylbenzamides, and mono‐ para ‐substituted benzophenones, using [IrH 2 (Me 2 CO) 2 (PPh 3 ) 2 ]BF 4 as catalyst and deuterium gas as the source of isotope. In most cases, labelling was efficient and regioselective, with deuterium appearing in the positions ortho to the carbonyl‐containing functional group. Apparent from the results of these experiments was that, in each case the para ‐substituted rings were labelled more rapidly or to a greater extent than the corresponding unsubstituted rings, regardless of the identity of the substituent.