Bicyclic pyrimidone compounds

A compound of Formula (I) or a pharmaceutically acceptable salt thereof,

• wherein:
• R is H or C1-C6alkyl,
• R′ is H, halo, or C1-C6alkyl,
• X is —O—, —NH—, —N(C1-C6alkyl)-, —S— or —CH2—,
• n is 0, 1, 2 or 3, when X is —CH2—, n is 1 or 2,
• Ar is phenyl or heteroaryl, either of which is unsubstituted or substituted with one or more groups selected from the group consisting of CN, halo, OH, —NH2, —NHR1, —NR1R2, C1-C6alkyl, C1-C6alkoxy, and C1-C6haloalkyl, and
• Y is absent or —O—Ar′, —NH—Ar′, —N(C1-C6alkyl)-Ar′, or —(CH2)—Ar′,
• wherein Ar′ is phenyl or heteroaryl, either of which is unsubstituted or substituted with one or more groups selected from the group consisting of CN, halo, OH, —NH2, —NHR1, —NR1R2, C1-C6alkyl, C1-C6alkoxy, and C1-C6haloalkyl, and
• each occurrence of R1 and R2 are independently C1-C6 alkyl.