| 主权项 |
1. A compound of Formula (I), or a pharmaceutically acceptable salt thereof: wherein: B1 is an optionally substituted heterocyclic base or an optionally substituted heterocyclic base with a protected amino group; X1 is O (oxygen) or S (sulfur); R1 is selected from the group consisting of —Z1—R9, an optionally substituted N-linked amino acid and an optionally substituted N-linked amino acid ester derivative; Z1 is selected from the group consisting of O (oxygen), S (sulfur) and N(R10); R2 and R3 are independently selected from the group consisting of hydrogen, an optionally substituted C1-6 alkyl, an optionally substituted C2-6 alkenyl, an optionally substituted C2-6 alkynyl, an optionally substituted C1-6 haloalkyl and an optionally substituted aryl(C1-6 alkyl); or R2 and R3 are taken together to form a group selected from the group consisting of an optionally substituted C3-6 cycloalkyl, an optionally substituted C3-6 cycloalkenyl, an optionally substituted C3-6 aryl and an optionally substituted C3-6 heteroaryl; R4 is selected from the group consisting of hydrogen, halogen, azido, cyano, an optionally substituted C1-6 alkyl, an optionally substituted C2-6 alkenyl, an optionally substituted C2-6 alkynyl and an optionally substituted allenyl; R5 is hydrogen or an optionally substituted C1-6 alkyl; R6 is selected from the group consisting of hydrogen, halogen, azido, amino, cyano, an optionally substituted C1-6 alkyl, —OR11 and —OC(═O)R12; R7 is selected from the group consisting of hydrogen, halogen, azido, cyano, an optionally substituted C1-6 alkyl, —OR13 and —OC(═O)R14; R8 is selected from the group consisting of hydrogen, halogen, azido, cyano, an optionally substituted C1-6 alkyl, —OR15 and —OC(═O)R16; R9 is selected from the group consisting of an optionally substituted alkyl, an optionally substituted alkenyl, an optionally substituted alkynyl, an optionally substituted cycloalkyl, an optionally substituted cycloalkenyl, an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted heterocyclyl, an optionally substituted aryl(C1-6 alkyl), an optionally substituted heteroaryl(C1-6 alkyl), an optionally substituted heterocyclyl(C1-6 alkyl) and Formula (II); R10 is selected from the group consisting of hydrogen, an optionally substituted alkyl, an optionally substituted alkenyl, an optionally substituted alkynyl, an optionally substituted cycloalkyl, an optionally substituted cycloalkenyl, an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted heterocyclyl, an optionally substituted aryl(C1-6 alkyl), an optionally substituted heteroaryl(C1-6 alkyl) and an optionally substituted heterocyclyl(C1-6 alkyl); R11, R13 and R15 are independently hydrogen or an optionally substituted C1-6 alkyl; R12, R14 and R16 are independently an optionally substituted C1-6 alkyl or an optionally substituted C3-6 cycloalkyl; provided that if X1 is O (oxygen), and R1 is —O—R9 or —N(R10)—R9, then at least one of R2 and R3 is selected from the group consisting of an optionally substituted C1-6 alkyl, an optionally substituted C2-6 alkenyl, an optionally substituted C2-6 alkynyl, an optionally substituted C1-6 haloalkyl and an optionally substituted aryl(C1-6 alkyl), or R2 and R3 are taken together to form a group selected from the group consisting of an optionally substituted C3-6 cycloalkyl, an optionally substituted C3-6 cycloalkenyl, an optionally substituted C3-6 aryl and an optionally substituted C3-6 heteroaryl; wherein Formula (II) is: R20 and R21 are independently selected from the group consisting of hydrogen, an optionally substituted C1-24 alkyl and an optionally substituted aryl; R22 is selected from the group consisting of hydrogen, an optionally substituted C1-24 alkyl, an optionally substituted aryl, an optionally substituted —O—C1-24 alkyl and an optionally substituted —O-aryl; and Y1 is O (oxygen) or S (sulfur); and provided that a compound of Formula (I) cannot be |
