FLUORINATED HETEROCYCLIC COMPOUNDS: SELECTIVE CHLORONE/FLUORINE EXCHANGE REACTIONS ON PYRIMIDINES

Article abstract of DOI:10.1016/S0022-1139(00)81461-X

Selective chlorine/fluorine exchange reactions on tetrachloropyrimidine, 6-methyl-, 6-chloromethyl-, 6-dichloromethyl, and 6-trichloromethyl-2,4,5-trichloropyrimidine are described.Sodium fluoride, potassium fluoride, hydrogen fluoride, and antimony trifluoride were used as the fluorinating agents.It was found that NaF and KF fluorinate only in the heterocyclic nucleus, HF in the nucleus and in the chlorinated methyl group, and SbF3 only in the chlorinated methyl group.In the first stage of fluorination with NaF only chlorine bound in position 4 of the pyrimidine ring is exchanged.The HF reaction is an equilibrium reaction in which the substitution of the fluorine for the first chlorine atom occurs preferentially in position 2.The behaviour of partly fluorinated pyrimidines in nucleophilic exchange reactions is also discussed.