The invention relates to a compound, and pharmaceutically acceptable salts, having formula (I), wherein: R represents an alkyl or alkynyl group having 1-4 carbon atoms, or a phenyl group optionally substituted by C1-4 alkyl, alkylthio, alkoxy, halogen, nitro, acylamino, methylsulfonyl or methylenedioxy, or represents tetrahydronaphthyl; R1 represents hydrogen, trifluoro (C¿1-4?) alkyl, alkyl or alkynyl; X represents hydrogen, alkyl having 1-4 carbon atoms, alkoxy, trifluoroalkyl, hydroxy, halogen, methylthio or aralkoxy; R?2¿ represents: a C¿1?-C10 alkyl group; a phenyl group optionally substituted by one or more of the following groups: a C1-C10 alkyl group, a halogen group, a nitro group, hydroxy group, and/or an alkoxy group.