Pyrrolidine derivatives

A compound of formula (I)

• wherein
• A1 is S or SO2;
• A2 is
• A3 is cycloalkyl, substituted cycloalkyl, piperidinyl, substituted piperidinyl, tetrahydropyranyl, dimethyltetrahydropyranyl, tetrahydrothiopyranyl, morpholinyl, thiomorpholinyl, pyrrolidinyl, piperazinyl, substituted piperazinyl or azepanyl, wherein substituted cycloalkyl is cycloalkyl substituted with one or two substitutents independently selected from halogen and alkyl, wherein substituted piperidinyl is piperidinyl substituted with one substituent selected from alkyl, phenyl, 3-methyl-[1,2,4]thiadiazol-5-yl, acetyl, haloalkyl, alkoxycarbonyl and alkylsulfonyl or with two substituents independently selected from alkyl, and wherein substituted piperazinyl is piperazinyl substituted with one substituent selected from alkyl, alkoxycarbonyl, acetyl, formyl, alkylsulfonyl and haloalkylcarbonyl;
• and
• R1, R2 and R3 are independently selected from hydrogen, halogen, alkyl, haloalkyl, alkoxy and haloalkoxy;
• or a pharmaceutically acceptable salt or ester thereof.