Compound of formula (I): ** Formula ** in which: X represents NR ', S or O； HetAr represents a phenyl or heteroaryl, optionally substituted with one or more substituents selected from halogen, OR '', alkyl, cyano, NR''R '", -COR' ', -COOR' ', -CONR''R'" , aryl, alkylaryl； R represents a lower alkyl or H R 'represents H, lower alkyl, alkoxyalkyl or alkoxycarbonyl； R ", R" identical or different independently represent H or alkyl； HET represents a non-aromatic monocyclic heterocycle containing at least one nitrogen atom, which is attached to R； B represents a single bond or a group -CH2-； A represents O, NH or S； Ar is a monocyclic or polycyclic aromatic or a monocyclic or polycyclic heteroaromatic which may be optionally substituted with one or more of: · halo； azido； cyano； hydroxy； nitro； · alkyl； alkoxy； alkylsulfanyl； alkenyl； alkynyl； alkenyloxy； alkenyloxy； alkenylsulfanyl； alkylsulfanyl； cycloalkoxy； cycloalkylalkyl； whose alkyl, alkenyl, alkynyl or cycloalkyl part may be substituted with one or more of halo, hydroxy, polyhydroxy, alkoxy, hydroxyalkoxy, cyano, amino, amino , dialkylamino, aminoalkylamino, aminoalkylaminocarbonyl, alkoxycarbonylamino, diarylmethylimino (where aryl is optionally substituted with one or more hydroxy or halo), cycle alquenilimino (where cycloalkenyl is optionally substituted with one or more of alkyl, OH), alkylsulfanyl, alkylsulfinyl, alkylsulfonyl, cycloalkyl, polycycloalkyl, cycloalkenyl, polycycloalkenyl, guanidino, alquilcarbonilguanidino, acylguanidino, cyanoguanidino, alcoxicarbonilguanidino, alkoxycarbonyl, alkoxycarbonylalkylamino, alcoxicarbonilalquilcicloalquilo, alcoxicarbonilheterociclilo, aminocarbonyl , alkylaminocarbonyl, alkylcarbonyl, alkylcarbonylalkoxy, aryloxy, arylsulfanyl, arylsulfinyl, arylsulfonyl, heteroaryl, heterocyclyl (where heterocyclyl optionally substituted with one or more of oxo, amino, imino), heteroaryloxy, heterocyclyloxy, heteroarylamino, heterocyclylamino, hydrazinocarbonyl, hydroxyalkylcycl
