Pd-catalysed hydrodehalogenation of aryl chlorides: a mild method for deuteration and detoxification

(Poly)halogenated arenes are important electrophiles in organic synthesis but often also toxic and harmful to human health and the environment. Hydrodehalogenation represents a powerful method for detoxification, but usually requires harsh reaction conditions. Here we report on the hydrodehalogenation of a series of chloro- and polyhalogenated compounds under mild reaction conditions using palladium complexes with ylide-substituted phosphines (YPhos) as ligands. The dehalogenation is accomplished with ethanol as the hydride source in MeTHF, including polychlorinated biphenyls (PBCs) extracted from construction dust. In addition, the haloarenes cannot only be detoxified but also applied in site-selective deuterations under the same reaction conditions by simply switching to deuteroethanol.