A mixture of 2-[2-(2,2,2-trifluoroethyl)guanidino]-4-(4-aminobutyl)thiazole (0.7 g.) and 2-nitroamino-5-methyl-4(3H)-pyrimidone (0.3 g.) was heated under reflux in pyridine (3 ml.) for 3.5 hours. The mixture was then evaporated to dryness and the residue purified by preparative thin layer chromatography using ethyl acetate/methanol/ 6:1:1 v/v/v for development. The appropriate band was extracted with chloroform/ethanol 1:1 v/v (200 ml.). Evaporation of the solvent to dryness gave a red gum which was treated in acetone with excess maleic acid to give 5-methyl-2-(4-[(-2-[2,2,2-trifluoroethyl]guanidino)thiazol-4-yl]butylamino)pyrimid-4-one containing 1.75 equivalents of maleic acid. The n.m.r. of this compound in d6 dimethylsulphoxide using tetramethylsilane as internal standard (δ=0) included the following resonances (δ): 1.6 (multiplet, 4H); 1.8 (singlet, 3H); 3.3 (multiplet, 2H); 4.2 (quartet, 2H); 6.6 (singlet, 1H); 7.5 (singlet, 1H).
