主权项 |
1. A compound represented by formula (I) or a pharmaceutically acceptable salt, wherein: R1 and R2 are independently selected from the group consisting of hydrogen, methyl and ethyl; R1 and R2 together can be ═O; also, R1 and R2 together with the carbon atom connecting them can form a 3-membered carbon ring; A is selected from the group consisting of phenyl, R3-substituted phenyl, pyridinyl, R4-substituted pyridinyl, pyrimidinyl, R5-substituted pyrimidinyl, pyrrolyl, R6-substituted pyrrolyl, pyridazinyl, R7-substituted pyridazinyl, pyrazolyl, and R8-substituted pyrazolyl; R3 is 1 to 5 substituents independently selected from the group consisting of halogen, (C1-C3) alkyl, (C2-C3) alkenyl, (C3-C4) cycloalkyl, (C1-C3) alkoxy, trifluoromethyl and cyano; R4 is 1 to 4 substituents independently selected from the group consisting of halogen, (C1-C3) alkyl, (C2-C3) alkenyl, (C3-C4) cycloalkyl, (C1-C3) alkoxy, trifluoromethyl and cyano; R5 is 1 to 3 substituents independently selected from the group consisting of halogen, (C1-C3) alkyl, (C2-C3) alkenyl, (C3-C4) cycloalkyl, (C1-C3) alkoxy, trifluoromethyl and cyano; R6 is 1 to 4 substituents independently selected from the group consisting of (C1-C3) alkyl, (C2-C3) alkenyl and (C3-C4) cycloalkyl; R7 is 1 to 3 substituents independently selected from the group consisting of halogen, (C1-C3) alkyl, (C2-C3) alkenyl, (C3-C4) cycloalkyl, (C1-C3) alkoxy, trifluoromethyl and cyano; R8 is 1 to 3 substituents independently selected from the group consisting of (C1-C3) alkyl, (C2-C3) alkenyl and (C3-C4) cycloalkyl. |