A compound of formula (I) in which R1 is selected from the group consisting of alkyl- (C1-C6), cycloalkyl- (5 C3-C7), phenyl, 4-7 membered heterocycloalkyl and 5-10 heteroaryl members, wherein (i) said cycloalkyl- (C3-C7), phenyl, 4-7 membered heterocycloalkyl and 5-10 membered heteroaryl are optionally substituted with one or two substituents independently selected from the group consisting of fluorine, chlorine, bromine, difluoromethyl, trifluoromethyl, alkyl- (C1-C4), oxo, hydroxy, difluoromethoxy, trifluoromethoxy, alkoxy- (C1-C4), amino, mono-alkylamino- (C1-C4), di-alkylamino- (C1 -C4) and cycloalkyl- (C3-C6), and (ii) said alkyl- (C1-C6) is optionally substituted with one, two or three substituents independently selected from the group consisting of fluorine, trifluoromethyl, hydroxy, alkoxy- (C1-C4), amino, mono-alkylamino- (C1-C4), di-alkylamino- (C1-C4), hydroxycarbonyl, alkoxycarbonyl- (C1-C4), aminocarbonyl, mono-alq uylaminocarbonyl- (C1-C4), dialkylaminocarbonyl- (C1-C4), cycloalkyl- (C3-C7), phenyl, 4-7 membered heterocycloalkyl and 5-10 membered heteroaryl, in which said cycloalkyl substituents- (C3-C7), phenyl, 4-7 membered heterocycloalkyl and 5-10 membered heteroaryl are optionally substituted with one or two residues independently selected from the group consisting of fluorine, chlorine, bromine, difluoromethyl, trifluoromethyl, alkyl- ( C1-C4), oxo, hydroxy, difluoromethoxy, trifluoromethoxy, alkoxy- (C1-C4), amino, mono-alkylamino- (C1-C4), di-alkylamino- (C1-C4) and cycloalkyl- (C3-C6) , or R1 is a group of the formula -NR8R9, -C (= O) -NR10R11, -SO2-NR12R13, -NR14-C (= O) -R15, -NR16-SO2-R17, -OR18 25 or -S ( = O) n-R19, where n is 0, 1 or 2, R8, R9, R10, R11, R12 and R13 are independently selected from the group consisting of hydrogen, alkyl- (C1-C6), cycloalkyl- (C3-C7), phenyl, 4-7 membered heterocycloalkyl and 5-10 heteroaryl 3 0 members, wherein (i) said cycloalkyl- (C3-C7), phenyl, 4-7 membered heterocycloalkyl and 5-10 membered heteroa
