A compound of formula wherein A is alkyl, hydroxyalkyl, -CH 2 C -, -C -, -SO 2 - or absent; R 1 is hydrogen, alkyl, haloalkyl, hydroxyl, alkoxy, haloalkoxy, phenyl, halophenyl, alkoxyphenyl, haloalkylphenyl, haloalkoxyphenyl, (halo)(haloalkyl)phenyl, cyanophenyl, hydroxyalkoxyphenyl, alkylsulfonylphenyl, alkylsulfonylaminophenyl, cyano, cycloalkyl, cycloalkylalkoxy, amino, (alkylsulfonyl)(alkyl)[1,2,4]triazolyl, (halo)(dialkylamino)pyridinyl, (alkyl)(oxy)pyridinyl, nitro-benzo[1,2,5]oxadiazolylaminopyridinyl, heterocyclyl, alkylheterocyclyl, hydroxyheterocyclyl, alkylheterocyclyl, heteroaryl, haloheteroaryl, alkylheteroaryl, cycloalkylheteroaryl or haloalkylheteroaryl, wherein heterocyclyl is a three to eight membered carbocyclic ring comprising at least one nitrogen or oxygen atom, and wherein heteroaryl is pyridinyl, pyrazolyl, oxadiazolyl, furazanyl, tetrazolyl or triazolyl; R 2 is halogen or -NR 3 R 4 or -OR 5; one of R 3 and R 4 is hydrogen or alkyl and the other one is alkyl or cycloalkyl; or R 3 and R 4 together with the nitrogen atom to which they are attached form heterocyclyl or substituted heterocyclyl, wherein heterocyclyl is morpholinyl, piperidinyl, piperazinyl, pyrrolidinyl, 2-oxa-6-azaspiro[3.3]heptyl, azetidinyl, thiazolidinyl, thiomorpholinyl, dioxothiomorpholinyl, oxazepanyl, 2-oxa-6-azaspiro[3.4]octyl, 6-oxa-1-azaspiro[3.3]heptyl, 2-oxa-5-aza-spiro[3.4]octyl, isoxazolidinyl, aziridinyl, dioxoisothiazolidinyl or oxopyrolidinyl and wherein substituted heterocyclyl is heterocyclyl substituted with one to four substituents independently selected from alkyl, halogen, hydroxyl, alkoxy, hydroxyalkyl, carboxyl, alkoxyalkyl, cyano, alkylamino, dialkylamino, alkylcarbonylamino, alkylcarbonyl(alkylamino), phenyl, alkoxycarbonyl, aminoalkyl, alkylpyrazolyl or alkylisoxazolyl; R 5 is alkyl, cycloalkyl, cycloalkylalkyl, haloalkyl or oxetanyl; or a pharmaceutically acceptable salt or ester thereof; wherein "alkyl", alone or in combination, is a straight-chain or branched-chain alkyl group with 1 to 8 carbon atoms; "cycloalkyl", alone or in combination, is a cycloalkyl ring with 3 to 8 carbon atoms; and "alkoxy", alone or in combination, is a group of the formula alkyl-O-; with the proviso that 3-[(2-chlorophenyl)methyl]-5-(1,1-dimethylethyl)-7-(4-morpholinyl)-3H-1,2,3-triazolo[4,5-d]pyrimidine and N-cyclopropyl-5-(1,1-dimethylethyl)-3-(phenylmethyl)-3H-1,2,3-triazolo[4,5-d]pyrimidin-7-amine are excluded. A is alkyl, hydroxyalkyl, -CH 2 C -, -C -, -SO 2 - or absent; R 1 is hydrogen, alkyl, haloalkyl, hydroxyl, alkoxy, haloalkoxy, phenyl, halophenyl, alkoxyphenyl, haloalkylphenyl, haloalkoxyphenyl, (halo)(haloalkyl)phenyl, cyanophenyl, hydroxyalkoxyphenyl, alkylsulfonylphenyl, alkylsulfonylaminophenyl, cyano, cycloalkyl, cycloalkylalkoxy, amino, (alkylsulfonyl)(alkyl)[1,2,4]triazolyl, (halo)(dialkylamino)pyridinyl, (alkyl)(oxy)pyridinyl, nitro-benzo[1,2,5]oxadiazolylaminopyridinyl, heterocyclyl, alkylheterocyclyl, hydroxyheterocyclyl, alkylheterocyclyl, heteroaryl, haloheteroaryl, alkylheteroaryl, cycloalkylheteroaryl or haloalkylheteroaryl, wherein heterocyclyl is a three to eight membered carbocyclic ring comprising at least one nitrogen or oxygen atom, and wherein heteroaryl is pyridinyl, pyrazolyl, oxadiazolyl, furazanyl, tetrazolyl or triazolyl; R 2 is halogen or -NR 3 R 4 or -OR 5; one of R 3 and R 4 is hydrogen or alkyl and the other one is alkyl or cycloalkyl; or R 3 and R 4 together with the nitrogen atom to which they are attached form heterocyclyl or substituted heterocyclyl, wherein heterocyclyl is morpholinyl, piperidinyl, piperazinyl, pyrrolidinyl, 2-oxa-6-azaspiro[3.3]heptyl, azetidinyl, thiazolidinyl, thiomorpholinyl, dioxothiomorpholinyl, oxazepanyl, 2-oxa-6-azaspiro[3.4]octyl, 6-oxa-1-azaspiro[3.3]heptyl, 2-oxa-5-aza-spiro[3.4]octyl, isoxazolidinyl, aziridinyl, dioxoisothiazolidinyl or oxopyrolidinyl and wherein substituted heterocyclyl is heterocyclyl substituted with one to four substituents independently selected from alkyl, halogen, hydroxyl, alkoxy, hydroxyalkyl, carboxyl, alkoxyalkyl, cyano, alkylamino, dialkylamino, alkylcarbonylamino, alkylcarbonyl(alkylamino), phenyl, alkoxycarbonyl, aminoalkyl, alkylpyrazolyl or alkylisoxazolyl; R 5 is alkyl, cycloalkyl, cycloalkylalkyl, haloalkyl or oxetanyl;