Catalytic synthesis of phenols with nitrous oxide.

The development of catalytic chemical processes that enable the revalorization of nitrous oxide (N 2 O) is an attractive strategy to alleviate the environmental threat posed by its emissions 1-6 . Traditionally, N 2 O has been considered an inert molecule, intractable for organic chemists as an oxidant or O-atom transfer reagent, owing to the harsh conditions required for its activation (>150 °C, 50‒200 bar) 7-11 . Here we report an insertion of N 2 O into a Ni‒C bond under mild conditions (room temperature, 1.5-2 bar N 2 O), thus delivering valuable phenols and releasing benign N 2 . This fundamentally distinct organometallic C‒O bond-forming step differs from the current strategies based on reductive elimination and enables an alternative catalytic approach for the conversion of aryl halides to phenols. The process was rendered catalytic by means of a bipyridine-based ligands for the Ni centre. The method is robust, mild and highly selective, able to accommodate base-sensitive functionalities as well as permitting phenol synthesis from densely functionalized aryl halides. Although this protocol does not provide a solution to the mitigation of N 2 O emissions, it represents a reactivity blueprint for the mild revalorization of abundant N 2 O as an O source.