One class of pyrazolone compounds and use thereof

A compound of formula I, or a pharmaceutically acceptable salt thereof:

• wherein the structure is:
• R1 is selected from the group consisting of 6- to 12-membered aryl group and 5-10 membered heteroaryl in which hydrogen atoms on the group are optionally substituted with one or more substituents selected from the group consisting of halogen, C1-C4 alkyl, C1-C4 halogen substituted alkyl, adamantyl, hydroxyl, amino, nitro, substituted or unsubstituted acetoxy group (AcO), carboxyl, C1-C4 alkoxy, C1-C4 haloalkoxy, cyano, substituted or unsubstituted phenyl, and —SO2—NH2;
• wherein the term “substituted” as used with respect to the C1-C4 halogen substituted alkyl, substituted or unsubstituted acetoxygroup (AcO), and substituted or unsubstituted phenyl refers to one or more hydrogen atoms on the group being substituted with substituents selected from the group consisting of halogen, trifluoromethyl, hydroxy, amino, C1-C4 alkyl, C1-C4 alkoxy, adamantyl, and cyano;
• R4 is selected from the group consisting of H, C1-C4 alkyl, C1-C4 haloalkyl, halogen, hydroxy, amino, nitro, AcO, carboxyl, C1-C4 alkoxy, and cyano;
• R5 is selected from the group consisting of H, C1-C4 alkyl, C3-C7 cycloalkyl, C1-C4 alkylene-C3-C7 cycloalkyl, phenyl, C1-C4 alkylene phenyl, wherein hydrogen atoms on phenyl or C1-C4 alkylene phenyl are optionally substituted by one or more substituents selected from the group consisting of hydroxy, halogen, C1-C4 alkyl, C1-C4 haloalkyl, C3-C7 cycloalkyl, C1-C4 alkoxy, and C1-C4 haloalkoxy;
• wherein when R5 is a phenyl-containing group, the hydrogen atoms of two adjacent carbons on the phenyl are optionally substituted by “—O—(CH2)nO—”, wherein n=1, 2 or 3;
• n3 is 0, 1, or 2;
• X is selected from the group consisting of 0 and NR8, wherein R8 is selected from the group consisting of H, C1-C4 alkyl, C1-C4 haloalkyl, C3-C7 cycloalkyl, phenyl, and C1-C4 alkylene phenyl.