Novel Organoruthenium(II) β‑Diketonates as Catalysts for Ortho Arylation via C–H Activation

Five different fluorinated β-diketone ligands in
the presence
of sodium methoxide easily react with the organoruthenium precursor
[(η6-p-cymene)­Ru­(μ-Cl)­Cl]2, generating neutral complexes 1–5 with typical “piano-stool” geometry. All synthesized
compounds were characterized by multinuclear NMR, X-ray diffraction,
and other standard physicochemical methods. These isolated organoruthenium­(II)
complexes are air-, moisture-, and UV-stable compounds and were tested
for catalytic activity. It was found that these compounds are ready
to use catalysts, which are efficient for direct arylation of 2-phenylpyridine.
With the use of 4-bromoacetophenone as arylating reagent, these complexes
show enhanced selectivity for monoarylated products. All reagents
are commercially available and relatively inexpensive, which makes
these catalysts generally available.