C−F Bond Activation in Organic Synthesis

TBAF-Catalysed Facile Synthesis of Unsymmetrical Diaryl Thioethers via Mild SNAr Reactions

By using tetrabutylammonium fluoride as the catalyst, the synthesis of unsymmetrical diaryl thioethers could be easily achieved in high yields via a mild nucleopilic aromatic substitution reaction of aryl fluorides and phenylthiotrimethylsilane.

Mechanism of lithium diisopropylamide-mediated substitution of 2,6-difluoropyridine

Treatment of 2,6-difluoropyridine with lithium diisopropylamide in THF solution at -78 degrees C effects ortholithiation quantitatively. Warming the solution to 0 degrees C converts the aryllithium to 2-fluoro-6-(diisopropylamino)pyridine. Rate studies reveal evidence of a reversal of the ortholithiation and a subsequent 1,2-addition via two monomer-based pathways of stoichiometries [ArH*i-Pr(2)NLi(THF)](double dagger) and [ArH*i-Pr(2)NLi(THF)(3)](double dagger). Computational studies fill in the structural details and provide evidence of a direct substitution without the intermediacy of a Meisenheimer complex.

Synthesis and reactivity of palladium(II) fluoride complexes containing nitrogen-donor ligands

This article describes the synthesis, characterization, and reactivity of palladium(II) fluoride complexes containing sp(2) and sp(3) nitrogen-containing supporting ligands. Both cis and trans complexes of general structure (N)(N')Pd(II)(R)(F) (R = Ar or CH(3)) as well as cis-(N)(2)Pd(II)(F)(2) are reported. Crystallographic characterization of these molecules has allowed structural comparisons to related phosphine-ligated species. Furthermore, these studies have revealed that nitrogen-donor ligands support some of the longest and the shortest Pd-F bonds reported to date. The thermal decomposition of (N)(N')Pd(II)(R)(F) has also been examined, and no products of C-F bond-forming reductive elimination were obtained in any case.