Abstract: Compounds of the formula ##STR1## (wherein X represents a halogen atom; n is 0, 1 or 2; R.sup.1 and R.sup.2, which may be the same or different, each represents a hydrogen atom or a carboxyl, esterified carboxyl, amido or mono- or di-C.sub.1-4 alkylamido group or a C.sub.1-4 alkyl group which may if desired carry a carboxyl or esterified carboxyl group; and R.sup.3 represents a C.sub.1-32 saturated or unsaturated, straight or branched, cyclic or acyclic aliphatic group or an araliphatic or heterocyclic substituted aliphatic group, a heterocyclic group or an aryl group which groups may if desired carry one or more substituents selected from halogen atoms and oxo, nitro, hydroxy, etherified hydroxy, esterified hydroxy, primary, secondary or tertiary amino, acylamino etherified mercapto or S.dbd.O or --SO.sub.

Abstract: Novel derivatives of pyrimid-2-one having interesting pharmacological properties are described. The compounds of the invention have been found to be of use in the control of, and in particular in the inhibition of the metaphase of malignant tumours and leukaemias. Processes for the preparation of the novel compounds and pharmaceutical compositions containing them are also described.