Manganese-catalyzed selective C-H activation and deuteration by means of a catalytic transient directing group strategy.

A novel manganese-catalyzed C-H activation methodology for selective hydrogen isotope exchange of benzaldehydes is presented. Using DO as a cheap and convenient source of deuterium, the reaction proceeds with excellent functional group tolerance. High ortho-selectivity is achieved in the presence of catalytic amounts of specific amines, which in situ form a transient directing group.