Borohydride exchange resin as an alternative method for deuterium labelling: selective reduction of aryl bromides

Transition metal-activated borohydride exchange resin and borodeuteride exchange resin have been prepared and used for the selective reductive deuteration of aryl bromides. This methodology, which utilizes deuterated methanol as the primary source of label, provides an alternative method for the introduction of deuterium. Investigation of which bond in the solvent donates the deuterium and model reductions on ortho-bromo-N,N-dimethylbenzamide suggest that an organocopper(III) intermediate is most likely involved. The immobilized hydride on resin also provides an easy workup and gives products of high purity. This methodology is far more selective than typical catalytic deuteration and, in most cases, provides products with high levels of deuterium incorporation. Copyright (C) 2001 John Wiley & Sons, Ltd.