Disclosed is a compound represented by Formula (I) or a pharmaceutically acceptable salt thereof: wherein R 1 is 1: a C 3-8 cycloalkyl C 1-4 alkyl group, 2: a C 7-14 aralkyl group, in which the aryl moiety thereof is optionally substituted with the same or different 1 to 3 groups selected from the group consisting of: (a) halogen, (b) C 1-4 alkyl, which is optionally substituted with 1 to 3 fluorine atoms, (c) C 1-4 alkoxy, which is optionally substituted with 1 to 3 fluorine atoms, and (d) C 1-4 alkylcarbonyl, which is optionally substituted with C 1-4 alkoxy, 3: a five- to ten-membered heteroaryl-C 1-4 alkyl group, in which the heteroaryl moiety thereof is optionally substituted with the same or different 1 to 3 groups selected from the group consisting of: (a) halogen, and (b) C 1-4 alkyl, or 4: a C 6-10 aryl C 2-6 alkenyl group； and R 2 is a cyano group or a nitro group.本發明揭示一種式(I)所示之化合物或其藥學上容許之鹽：式中，R1為1：C3-8環烷基C1-4烷基；2：C7-14芳烷基，且該基之芳基部分可經選自下述(a)~(d)所構成群組中相同或異種的1~3個基取代：(a)鹵素原子、(b)C1-4烷基(亦可經1~3個氟原子取代)、(c)C1-4烷氧基(亦可經1~3個氟原子取代)及(d)C1-4烷羰基(亦可經C1-4烷氧基取代)；3：5員~10員雜芳基-C1-4烷基，且該基之雜芳基部分可經選自下述(a)~(b)所構成群組中之相同或異種的1~3個基所取代：(a)鹵素原子及(b)C1-4烷基；4：C6-10芳基C2-6烯基；R2為氰基或硝基。
