Outer-Sphere Electrophilic Fluorination of Organometallic Complexes

Organofluorine chemistry plays a
key role in materials science,
pharmaceuticals, agrochemicals, and medical imaging. However, the
formation of new carbon–fluorine bonds with controlled regiochemistry
and functional group tolerance is synthetically challenging. The use
of metal complexes to promote fluorination reactions is of great current
interest, but even state-of-the-art approaches are limited in their
substrate scope, often require activated substrates, or do not allow
access to desirable functionality, such as alkenyl C­(sp2)–F or chiral C­(sp3)–F centers. Here, we
report the formation of new alkenyl and alkyl C–F bonds in
the coordination sphere of ruthenium via an unprecedented outer-sphere
electrophilic fluorination mechanism. The organometallic species involved
are derived from nonactivated substrates (pyridine and terminal alkynes),
and C–F bond formation occurs with full regio- and diastereoselectivity.
The fluorinated ligands that are formed are retained at the metal,
which allows subsequent metal-mediated reactivity.