The scope and limitations of deuteration mediated by Crabtreeʹs catalyst

Exchange of protons for deuterons mediated by Crabtreeʹs catalyst, 1, is directed efficiently by a functional group containing an sp2-hybridised nitrogen or oxygen atom; more electron-rich substrates are, in general, deuterated more efficiently. The electronic effects of substituents in the arene ring are critical only where the directing group is poor, in which case exchange is generally promoted by electron donating substituents, but the exchange is impeded by bulky meta-substituents.