Mechanistic considerations on catalytic HID exchange mediated by organometallic transition metal complexes

The purpose of this review is to analyze the different reaction mechanisms of the HID exchange on organic substrates catalyzed by transition metal complexes in homogeneous phase. The metal-catalyzed HID exchange is a multifaceted reaction whose mechanism depends strongly on the reaction conditions and on the metal complex used as a catalyst. It is possible to group the different mechanisms into three main families depending on the role and behavior of the catalyst: (i) Lewis acid-base catalysis; (ii) C-H activation (iii) insertion/beta-elimination. For each macro-group, several representative examples are discussed and critically evaluated in order to provide the reader with keys to the understanding of how the different catalytic systems act and how their modification may affect their performance in terms of activity and selectivity. This knowledge is fundamental for designing improved organometallic HID catalysts for labeling organic products in greener conditions with more cost-effective processes. (C) 2015 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.