Radical Anions of Aromatic Carbonitriles as Reagents for Arylation of Fluorinated Benzonitriles

The
first example of phenylation of fluorobenzonitriles with the
sodium salt of a benzonitrile radical anion in liquid ammonia is presented.
The reaction regioselectivity corresponds to the ortho- and para-fluorine atom substitution in fluorobenzonitrile
with the phenyl moiety of the benzonitrile radical anion and affords
2- and 4-cyanobiphenyls in 40–90% yields. 3-Methoxybenzonitrile
as well as 1-cyanonaphthalene radical anions were also successfully
subjected to this interaction forming 3′-methoxycyanobiphenyls
and (1-naphthyl)­benzonitriles, respectively. The radical anion acts
as an ipso-C-nucleophile with consequent loss of
the cyano group. The revealed new type of radical anion reactivity
opens up the prospect of developing a general approach to fluorinated
cyanobisarenes on the basis of an interaction of the cyanoarene radical
anion with fluorinated substrates activated to aromatic nucleophilic
substitution.