Patent ID: 8871737

Claim:
A compound of Formula (I) or a pharmaceutically acceptable salt thereof: wherein: B 1 is an optionally substituted purine base or an optionally substituted pyrimidine base; R 1 is an optionally substituted N-linked α-amino acid or an optionally substituted N-linked α-amino acid ester derivative; R 2 is an optionally substituted aryl; R 3a and R 3b are independently hydrogen, deuterium or methyl; R 4 is hydrogen; R 5 is hydrogen; R 6 is selected from the group consisting of hydrogen, halogen, —OR 12 and —OC(═O)R 13 ; R 7 is selected from the group consisting of hydrogen, halogen, —OR 14 and —OC(═O)R 15 ; or R 6 and R 7 are both oxygen atoms and linked together by a carbonyl group; R 8 is selected from the group consisting of hydrogen, halogen and an unsubstituted C 1-6 alkyl; R 9 is hydrogen; R 12 and R 14 are independently hydrogen or an unsubstituted C 1-6 alkyl; and R 13 and R 15 are independently an unsubstituted C 1-6 alkyl or an unsubstituted C 3-6 cycloalkyl; and wherein when a substituent is substituted, the substituent is substituted with a group individually and independently selected from C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-8 cycloalkyl, cycloalkenyl, C 6 -C 10 aryl, 4 to 14 atom heteroaryl, 3 to 18 atom heteroalicyclyl, (aryl)C 1-4 alkyl, (heteroaryl)C 1-4 alkyl, (heteroalicyclyl) C 1-4 alkyl, hydroxy, alkoxy, aryloxy, acyl, cyano, halogen, O-carbamyl, N-carbamyl, N-thiocarbamyl, C-amido, N-amido, S-sulfonamido, N-sulfonamido, C-carboxy, O-carboxy, nitro, sulfonyl, haloalkyl, haloalkoxy, an amino, a mono-substituted amino group and a di-substituted amino group.