title: Iridium-Catalysed ortho-Directed Deuterium Labelling of Aromatic Esters--An Experimental and Theoretical Study on Directing Group Chemoselectivity.
abstract: Herein we report a combined experimental and theoretical study on the deuterium labelling of benzoate ester derivatives, utilizing our developed iridium N-heterocyclic carbene/phosphine catalysts. A range of benzoate esters were screened, including derivatives with electron-donating and -withdrawing groups in the para- position. The substrate scope, in terms of the alkoxy group, was studied and the nature of the catalyst counter-ion was shown to have a profound effect on the efficiency of isotope exchange. Finally, the observed chemoselectivity was rationalized by rate studies and theoretical calculations, and this insight was applied to the selective labelling of benzoate esters bearing a second directing group.
authors.affiliation: Department of Pure & Applied Chemistry, University of Strathclyde, WestCHEM, 295 Cathedral Street, Glasgow G1 1XL, UK. jennifer.devlin.2013@uni.strath.ac.uk.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Devlin
authors.affiliation: Department of Pure & Applied Chemistry, University of Strathclyde, WestCHEM, 295 Cathedral Street, Glasgow G1 1XL, UK. w.kerr@strath.ac.uk.
authors.forename: William J
authors.initials: WJ
authors.lastname: Kerr
authors.affiliation: Department of Pure & Applied Chemistry, University of Strathclyde, WestCHEM, 295 Cathedral Street, Glasgow G1 1XL, UK. david.lindsay@strath.ac.uk.
authors.forename: David M
authors.initials: DM
authors.lastname: Lindsay
authors.affiliation: Department of Pure & Applied Chemistry, University of Strathclyde, WestCHEM, 295 Cathedral Street, Glasgow G1 1XL, UK. timothy.mccabe@strath.ac.uk.
authors.forename: Timothy J D
authors.initials: TJ
authors.lastname: McCabe
authors.affiliation: Department of Pure & Applied Chemistry, University of Strathclyde, WestCHEM, 295 Cathedral Street, Glasgow G1 1XL, UK. marc.reid@ed.ac.uk.
authors.forename: Marc
authors.initials: M
authors.lastname: Reid
authors.affiliation: Department of Pure & Applied Chemistry, University of Strathclyde, WestCHEM, 295 Cathedral Street, Glasgow G1 1XL, UK. tell.tuttle@strath.ac.uk.
authors.forename: Tell
authors.initials: T
authors.lastname: Tuttle
mesh_terms: D002384:Catalysis; D003903:Deuterium / Q000737:chemistry*; D004952:Esters; D007495:Iridium / Q000737:chemistry*; D008956:Models, Chemical; D066244:Proton Magnetic Resonance Spectroscopy
chemical_list: D004952:Esters; D007495:Iridium; D003903:Deuterium
keywords: C–H activation; DFT; deuterium; esters; hydrogen isotope exchange; iridium