Compound of formula (I): ** Formula ** in which: each R1 and R1a is independently selected from the group consisting of H, methyl, CONHC (CH3) 3, OH, CO2H, CO2CH3, CO2CH2CH3, phenyl , CH2OH, CN and OCH3. or any two R1 on adjacent carbon atoms can join to form a cyclic radical, or any two R1 of the same carbon can, when linked, form a group of the formula>； = O Ar is an optionally substituted C1-C18heteroaryl group, selected from the group consisting of: ** Formula ** in which each R7 is independently selected from the group consisting of H, halogen, OH, NO2, CN, SH, NH2, CF3, OCF3, C1-C12alkyl optionally substituted, optionally substituted C1-C12haloalkyl, optionally substituted C2-C12alkenyl, optionally substituted C2-C12alkynyl, optionally substituted C2-C12heteroalkyl, optionally substituted C3-C12cycloalkyl, optionally substituted-C12-cycloalkenyl, C2-cycloalkenyl, , Optionally substituted C6-C18aryl, optionally substituted C1-C18heteroaryl, optionally substituted C1-C12alkyloxy, C2-C12alkene optionally substituted yloxy, optionally substituted C2-C12alkynyloxy, optionally substituted C2-C10heteroalkyloxy, optionally substituted C3-C12cycloalkyloxy, optionally substituted C3-C12cycloalkenyloxy, optionally substituted C2-C12-cycloalkyl-alkyl-alkyloxy, optionally substituted heteroaryloxy, optionally substituted C1-C12alkylamino, SR9, SO3H, SO2NR9R10, SO2R9, SONR9R10, SOR9, COR9, COOH, COOR9, CONR9R10, NR9COR10, NR9COOR10, NR9SO2R10, NR9CONR9R10, NR9R wherein R8 is selected from the group consisting of H, optionally substituted C1-C12alkyl, optionally substituted C2-C12alkenyl, optionally substituted C2-C12alquinyl, optionally substituted C2-C12heteroalkyl, optionally substituted C3-C12cycloalkyl, C2-C12heterocycloalkyl, optionally Optionally substituted C6-C18aryl, optionally substituted C1-C18heteroaryl, SO3H, SO2NR9R10, SO2R9, SONR9R10, SOR9, COR9, COOH, COOR9 and CONR9R10； wherein each R9 and R10 is independently selected from the group consisting of H, opti
