Pyrazolo-triazine derivatives as ligands for GABA receptors

A compound of formula I, or a salt thereof:

• wherein
• Z represents halogen;
• or C1-6 alkyl, C3-7 cycloalkyl, C4-7 cycloalkenyl, C6-8 bicycloalkyl, di(C1-6)alkylamino, phenyl, azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, pyridinyl, quinolinyl, isoquinolinyl, pyridazinyl, pyrimidinyl, pyrazinyl, quinoxalinyl, furyl, benzofuryl, dibenzofuryl, thienyl, benzthienyl, pyrrolyl, indolyl, pyrazolyl, indazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, benzimidazolyl, oxadiazolyl, thiadiazolyl, triazolyl or tetrazolyl, which may be optionally substituted with a substitutent selected from C1-6 alkyl, phenylC1-6 alkyl, halogen, cyano, hydroxy, hydroxymethyl, C1-6 alkoxy and C3-7 cycloalkylC1-6 alkyl;
• R1 represents C3-7 cycloalkyl, phenyl, furyl, thienyl, pyridinyl or pyrazinyl, which may be optionally substituted with a substitutent selected from C1-6 alkyl, phenylC1-6 alkyl, halogen, cyano, hydroxy, hydroxymethyl, C1-6 alkoxy and C3-7 cycloalkylC1-6 alkyl;
• and
• R2 represents C3-7 cycloalkyl(C1-6)alkyl, phenyl(C1-6 alkyl), azetidinyl(C1-6 alkyl), pyrrolidinyl(C1-6 alkyl), piperidinyl(C1-6 alkyl), piperazinyl(C1-6 alkyl), morpholinyl(C1-6 alkyl), thiomorpholinyl(C1-6 alkyl), pyridinyl(C1-6 alkyl), quinolinyl(C1-6 alkyl), isoquinolinyl(C1-6 alkyl), pyridazinyl(C1-6 alkyl), pyrimidinyl(C1-6 alkyl), pyrazinyl(C1-6 alkyl), quinoxalinyl(C1-6 alkyl), furyl(C1-6 alkyl), benzofuryl(C1-6 alkyl), dibenzofuryl(C1-6 alkyl), thienyl(C1-6 alkyl), benzthienyl(C1-6 alkyl), pyrrolyl(C1-6 alkyl), indolyl(C1-6 alkyl), pyrazolyl(C1-6 alkyl), indazolyl(C1-6 alkyl), oxazolyl(C1-6 alkyl), isoxazolyl(C1-6 alkyl), thiazolyl(C1-6 alkyl), isothiazolyl(C1-6 alkyl), imidazolyl(C1-6 alkyl), benzimidazolyl(C1-6 alkyl), oxadiazolyl(C1-6 alkyl), thiadiazolyl(C1-6 alkyl), triazolyl(C1-6 alkyl) or tetrazolyl(C1-6 alkyl), which may be optionally substituted with a substitutent selected from C1-6 alkyl, phenylC1-6 alkyl, halogen, cyano, hydroxy, hydroxymethyl, C1-6 alkoxy and C3-7 cycloalkylC1-6 alkyl.