Barton–Zard Reaction of β‑Fluoro-β-nitrostyrenesa Selective Route to Functionalized 4‑Fluoropyrroles

The Barton–Zard reaction of β-fluoro-β-nitrostyrenes
with ethyl α-isocyanoacetate was studied. The reaction was found
to proceed in a highly chemoselective manner to form preferably 4-fluoropyrroles
in up to 77% yield. The corresponding 4-nitrosubstituted pyrroles
are formed as minor products of the reaction. The broad scope of β-fluoro-β-nitrostyrenes
was demonstrated in the preparation of a variety of fluorinated pyrroles.
The obtained experimental results are in perfect agreement with the
data obtained by theoretical investigation of this reaction. The subsequent
study of synthetic utility of monofluorinated pyrroles was performed
to open a way for the development of a variety of functionalized pyrrole
derivatives.