A compound of Formula I, ** Formula ** or a pharmaceutically acceptable salt thereof, wherein R1 is H, -C1-C5 alkyl, -O-C1-C5 alkyl, -C2-C5 alkenyl, -O-alkenyl C2-C5, -C2-C5 alkynyl, -O C2-C5 alkynyl, -OH, halogen, -CN, -NR6R7, -CO2R8, -C (O) NR6R7, -SO2NR6R7, HET (3) or C3-6 cycloalkyl which optionally has 1-2 double bonds, wherein each of -C1-C5 alkyl, -O-C1-C5 alkyl, -C2-C5 alkenyl, -O-C2-C5 alkenyl, -C2-C5 alkynyl and -O -C2-C5 alkynyl is optionally substituted with 1-7 halogens and wherein HET (3) and C3-6 cycloalkyl having optionally 1-2 double bonds are optionally substituted with 1-3 substituent groups each of which are independently halogen , -C1-C3 alkyl, -O-C1-C3 alkyl, -C2-C3 alkenyl, -O-C2-C3 alkenyl, -C2-C3 alkynyl or -O-C2-C3 alkynyl, wherein -C1-C3 alkyl , -C1-C3 alkyl, -C2-C3 alkenyl, -O-C2-C3 alkenyl, -C2-C3 alkynyl and -O-C2-C3 alkynyl are each optionally substituted with 1-7 ha logens； R6 and R7 are each independently H or -C1-C5 alkyl； R8 is H or -C1-5 alkyl optionally substituted with 1-7 halogens； HET (3) is a 3-6 membered heterocyclic ring that has 1-3 groups of heteroatoms each of which are independently N, NH, O, S, S (O) or S (O) 2 and that optionally have 1-3 double bonds； x is 0 or 1； The dashed lines in Formula I represent an optional double bond between 2 adjacent carbon atoms； D1 is N or CR2； D2 is N or CR3； D3 is N or CR4； R2, R3 and R4 are each independently H, -C1-C5 alkyl, -O-C1-C5 alkyl, -C2-C5 alkenyl, -O-C2-C5 alkenyl, -C2-C5 alkynyl, -O-C2 alkynyl -C5, -OH, halogen, -CN, -NR6R7, -CO2R8, -C (O) NR6R7 or -SO2NR6R7, where -C1-C5 alkyl, -O-C1-C5 alkyl, -C2-C5 alkenyl, - C2-C5 O-alkenyl, C2-C5 -alkynyl and -O-C2-C5 alkynyl are optionally substituted with 1-7 halogens； Each R5 is independently -C1-C5 alkyl, -O-C1-C5 alkyl, -C2-C5 alkenyl, -O-C2-C5 alkenyl, -C2-C5 alkynyl, -O-C2-C5 alkynyl, -OH, halogen , -CN, -NR6R7, -CO2R8, -C (O) NR6R7 or -SO2NR6R7, wherein -C1-C5 alkyl, -O-C1-C5 alkyl, -C2-C5 alkenyl, -O-C2-C5 alkenyl, -C2-C5 alk
