Birch Reductive Arylation by Mechanochemical Anionic Activation of Polycyclic Aromatic Compounds

Birch reduction is a well-known process for producing aromatic compounds. The reduction of aromatic rings using alkali metals produces anionic species that react with protons or electrophiles. However, this reaction is generally accompanied by signifi-cant restrictions on the available substrates because only alkyl halides are available in most cases. For example, most Birch reduction/transformation reactions are related to the alkylation of aromatic compounds, whereas reactions with other elec-trophiles are rare and have not yet been completely established. In particular, the arylation of unfunctionalized polycyclic ar-omatic hydrocarbons (PAHs), so-called Birch reductive arylation has not yet been investigated. Herein, we report a Birch re-ductive arylation for the first time by mechanochemical anionic activation using a lithium(0) wire followed by addition of vari-ous fluoroarenes. Specifically, we found that the not only Birch reductive arylation products but also formal C–H arylation products were obtained from unfunctionalized PAHs, achieving one-pot fissure-region annulative π-extension to give nanogra-phenes. This newly found process is a unique reaction that is rarely achieved in solution, and showed the interesting reactivity of metal lithium and organofluorine compounds in the solid state.