The present invention provides a compound represented by general formula (I):or pharmaceutically acceptable salts thereof, wherein R1and R2are each independently hydrogen, lower acyl, lower alkoxycarbonyl or the like R3is halo-lower alkyl, lower acyi, halo-lower alkylcarbonyl, cycloalkylcarbonyl, optionally substituted arylcarbonyl, lower alkokycarbonyl or the like R4is lower alkyl, halo-lower alkyl, cycloalkyl, lower alkoxy-lower alkyl or the like, which exhibits potent COMT inhibitory activities. The present invention also provides pharmaceutical compositions containing said compound, and uses thereof.本發明係提供一種具有強效之COMT抑制作用、以一般式(I)所示之化合物或其藥理學所容許之鹽,以及含有其之醫藥組成物及其等之用途。[一般式中,R1及R2分別為氫、低級醯基、低級烷氧基羰基等;R3為鹵素低級烷基、低級醯基、鹵素低級烷基羰基、環烷基羰基、可被取代之芳基羰基、低級烷氧基羰基等;R4為低級烷基、鹵素低級烷基、環烷基、低級烷氧基低級烷基等。]
