Polyhalogenated heterocyclic compounds

Model studies show that displacement of fluorine, rather than chlorine, occurs upon reaction of 3,5-dichloro-2,4,6-trifluoropyridine with sodium methoxide and phenoxide. Subsequent hydro-dechlorination can be achieved by reaction with lithium aluminium hydride whereas reaction of sodium in iso-propanol leads to formation of the tri-iso-propoxy pyridine derivative, via nucleophilic substitution of the methoxy group, rather than the dechlorinated products. Macrocycles can be synthesised by reactions of appropriate difunctional oxygen nucleophiles with 3,5-dichloro-2,4,6-trifluoropyridine, one of which was characterised by X-ray crystallography.