Inhibitors of flaviviridae viruses

A compound of Formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• R1 is -(L1)m-(L2)n-X1;
• L1 is selected from the group consisting of alkynylene and arylene;
• m is 1;
• L2 is selected from the group consisting of —NHC(O)— and alkylene;
• n is 0 or 1;
• X1 is selected from the group consisting of
• a) —P(O)RxRy,
• b) —P(O)ORxRy,
• c) —OP(O)RxRy and
• d) optionally substituted C1-12 alkyl, and 5-10 membered heteroaryl comprising one to three nitrogen atoms;
• each of Rx and Ry independently is selected from the group consisting of H, C1-12 alkyl, and C6-14 aryl;
• when X1 is selected from d) and is substituted, X1 is substituted with one or more halogen;
• R2 is optionally substituted C3-12 cycloalkyl;
• wherein, when R2 is substituted, R2 is substituted with one or more Q2;
• where each Q2 individually is selected from the group consisting of —OH, and optionally substituted C1-6 alkyl;
• when Q2 is substituted, Q2 is substituted with one or more halogen;
• R3 is -(L3)p-(L4)q-(X3);
• L3 is selected from the group consisting of optionally substituted C1-12 alkylene, optionally substituted C3-12 cycloalkylene and optionally substituted 5-6 membered N-containing heterocyclylene;
• p is 0 or 1;
• when L3 is substituted, L3 is substituted with one or more Q3,
• each Q3 individually is selected from the group consisting of —OH and C1-6 alkyloxy;
• L4 is selected from the group consisting of —NH—, and C1-12 alkylene;
• q is 0, 1 or 2;
• X3 is selected from the group consisting of:
• e) —P(O)RxRy,
• f) —P(O)ORxRy,
• g) —OP(O)RxRy,
• h) —P(O)(ORx)(ORy),
• wherein each A is a 4 to 6 membered ring, including the depicted P atom, and
• k) optionally substituted C3-12 cycloalkyl, and optionally substituted 3-12 membered heterocyclyl;
• each of Rx and Ry individually is as defined above;
• and
• when X3 is selected from k) and is substituted, X3 is substituted with one —OH;
• provided that when X1 is selected from d), then X3 is selected from the group consisting of e), f), g), h), and i).