biostudies-literatureUnknownTownsley JCHerein we report the first use of accessible boron-containing compounds as highly effective directing groups for C-H activation and hydrogen isotope exchange. Selective ortho-activation and functionalisation at aromatic C-sp2 centres have been achieved across an array of aryl boronic ester species using an iridium-based, NHC/phosphine catalyst system at low loadings. The process is robust, with a wide scope of over 30 substrates, and delivers excellent levels of deuterium incorporation in a selective manner. Further utilisation of the resulting boron-containing isotopologues in cross-coupling chemistry has allowed the late-stage preparation of previously less accessible site-selectively labelled structures. This strategy has been exemplified via the preparation of Chemical sciencehttps://www.ebi.ac.uk/biostudies/studies/S-EPMC12817062biostudies-literatureWidely-used boronic esters as synthetically-versatile directing groups for C-H activation and hydrogen isotope exchange.PMC12817062Paterson LCSmith CTownsley JCLiwicki GMLindsay DMMeasom NDKerr WJfalseWidely-used boronic esters as synthetically-versatile directing groups for C-H activation and hydrogen isotope exchange.Herein we report the first use of accessible boron-containing compounds as highly effective directing groups for C-H activation and hydrogen isotope exchange. Selective ortho-activation and functionalisation at aromatic C-sp2 centres have been achieved across an array of aryl boronic ester species using an iridium-based, NHC/phosphine catalyst system at low loadings. The process is robust, with a wide scope of over 30 substrates, and delivers excellent levels of deuterium incorporation in a selective manner. Further utilisation of the resulting boron-containing isotopologues in cross-coupling chemistry has allowed the late-stage preparation of previously less accessible site-selectively labelled structures. This strategy has been exemplified via the preparation of 2026-01-01T00:00:00Z2026 Jan2026-06-06T19:47:41.925Z2026-06-04T03:11:31.375ZS-EPMC128170624156795910.1039/d5sc09113f