Reactions of polyfluoropyridines with bidentate nucleophiles: attempts to prepare deazapurine analogues

Reactions of pentafluoropyridine with guanidine, thiourea and urea with the hope of preparing derivatives which may be cyclised to polyfluorodeazapuri nes are described The reactions with urea and thiourea produced, somewhat u nexpectedly, bis-(2,3.5.6-tetrafluoro-4-pyridyl)amine and bis-(2.3.5.6-tetr afluoro-4-pyridyl)sulfide respectively. the structure of the amine was conf irmed by X-ray crystallography. The product from the guanidine reaction was the expected 4-substituted tetrafluoropyridine derivative. Attempts to cyc lise the latter are described and a rationalisation to explain the unexpect ed melamine derivatives which were produced is given. (C) 2001 Elsevier Sci ence B.V. All rights reserved.