3-Fluoropyridyl nickel complexes as useful tools for the selective synthesis of new 2,4,5,6-tetrafluoropyridines: a route complementing the established methods to access fluorinated pyridines

New Journal of Chemistry Pub Date: 2002-12-12 DOI: 10.1039/B207943G

Abstract

Treatment of [Ni(COD)2] with 3-chlorotetrafluoropyridine in the presence of PEt3 or PCy3 effects the formation of the complexes trans-[NiCl(3-C5NF4)(PEt3)2] (1) and trans-[NiCl(3-C5NF4)(PCy3)2] (2), respectively. Reaction of 1 with MeLi gives trans-[NiMe(3-C5NF4)(PEt3)2] (3). Treatment of 3 with air yields 3-methyltetrafluoropyridine. The reaction of 1 with CO affords 1-(2,4,5,6-tetrafluoropyridin-3-yl)ethanone (6), which slowly converts into 1-(2,5,6-trifluoropyridin-3-yl)ethanone (7) in the presence of PEt3. The structure of the complexes 1 and 3 have been determined by X-ray crystallography. The Ni–C distances to the pyridyl ligand are 1.894(1) and 1.936(2) ?, respectively. The Ni–C bond length to the methyl group in 3 is 1.991(3) ?. The studies reported in this paper demonstrate the synthesis of nickel derivatives of tetrafluoropyridine with the metal in the 3-position as well as the preparation of otherwise not accessible 3-substituted tetrafluoropyridines by C–C coupling reactions.

Graphical abstract: 3-Fluoropyridyl nickel complexes as useful tools for the selective synthesis of new 2,4,5,6-tetrafluoropyridines: a route complementing the established methods to access fluorinated pyridines
Recommended Literature