Ureido and thioureido derivatives of 4-amino-2(5H)-furanones and 4-amino-2(5H)-thiophenones as antitumor agents

A method of preparing a medicament possessing antitumor activity comprising the compounds of formula (I) wherein said method comprises (a) providing at least one compound of formula (I), and (b) admixing therapeutically effective amounts of the at least one compound with pharmaceutically acceptable ingredients to prepare a medicament capable of oral, intravenous, intramuscular or subcutaneous administration,

• wherein:
• A is oxygen or sulfur;
• X is oxygen or sulfur;
• R1 and R2 are independently hydrogen or an alkyl group with from 1 to 6 carbon atoms;
• R is selected from:
• (C1-C10)alkyl, (C3-C7)cycloalkyl, (C1-C4)alkylthio, (C1-C4)alkylsulphinyl, (C1-C4)alkylsulphonyl, (C1-C4)hydroxyalkyl, naphthyl, phenyl, phenyl substituted by from 1 to 3 groups selected from:
• (C1-C4)alkyl;
• chlorine, bromine, iodine or fluorine;
• (C1-C4)perfluoroalkyl;
• hydroxy;
• (C1-C4)alkoxy;
• amino;
• mono- or di-(C1-C4)alkylamino;
• aminosulphonyl;
• (C1-C4)alkylsulphonamido;
• phenyl- or tolylsulphonamido;
• carboxy;
• (C1-C4)alkoxycarbonyl;
• amidocarbonyl or (C1-C4)alkylamidocarbonyl;
• carboxaldehyde;
• (C1-C4)alkylcarbonyl;
• nitro;
• phenylthio;
• cyanomethyl, and optionally substituted phenyloxy or optionally substituted phenyl-(C1-C4)alkyl or R is a 5- or 6-membered aromatic or non-aromatic heterocycle containing from 1 to 3 heteroatoms selected from oxygen, sulfur and nitrogen, which can be optionally benzocondensed, the pure stereoisomers or mixtures thereof as well as salts thereof with pharmaceutically acceptable acids or bases, with the proviso, that when A is oxygen and X is oxygen, R is not C1-C10)alkyl.