Antiviral compounds

A compound of formula I, formula II, or formula III:

• or a salt thereof, wherein:
• R1 is selected from the group consisting of:
• R2 is methyl or ethyl;
• R3 is phenyl, optionally substituted at the 3-position with bromo, chloro, fluoro, methyl, or methoxy, and optionally substituted at the 4-position with bromo, chloro, fluoro, methyl, or methoxy;
• R4 is 4-chloropyridyl, 4-bromopyridyl, or phenyl that is optionally substituted at the 4-position with halo, methyl, ethyl, or methoxy;
• R5 is selected from the group consisting of:
• R6 is a ring:
• which ring is optionally substituted with carboxy, (C1-C6)alkoxycarbonyl, or —C(═O)NRcRd;
• R7 is 4-chloropyridyl, 4-bromopyridyl, or phenyl that is optionally substituted at the 4-position with halo, methyl, ethyl, or methoxy;
• R8 is selected from the group consisting of:
• R9 is pyridyl that is substituted with phenyl, 4-chlorophenyl, 4-bromophenyl, 4-iodophenyl, or 4-cyanophenyl or R9 is imidazole that is substituted with phenyl, 4-chlorophenyl, 4-bromophenyl, 4-iodophenyl, or 4-cyanophenyl;
• R10 is 4-chloropyridyl, 4-bromopyridyl, or phenyl that is optionally substituted at the 4-position with halo, methyl, ethyl, or methoxy;
• Ra is H or methyl;
• Rb is phenyl that is optionally substituted with one or more groups independently selected from the group consisting of nitro, halo, (C1-C6)alkyl, halo(C1-C6)alkyl, hydroxy, —SO2F, and NReRf;
• Rc is H, phenyl, benzyl, or (C1-C6)alkyl;
• Rd is H, phenyl, benzyl, or (C1-C6)alkyl;
• Re is H, hydroxy, or (C1-C6)alkyl;
• Rf is H or (C1-C6)alkyl;
• Rg is H, OH, or (C1-C6)alkoxy;
• and
• Rh is H or (C1-C6)alkyl.