Antiviral benzyl-amine phosphodiamide compounds

1. A compound of structural Formula I:

or a pharmaceutically acceptable salt thereof, wherein:

R 1 is —C 1-6 alkyl;

R 2 is —C 1-6 alkyl;

or R 1 and R 2 are joined together with the carbon to which they are both attached to form spiro-C 3-6 cycloalkyl;

R 3 is:

(a) —C 1-10 alkyl unsubstituted or substituted with one, two or three of fluoro, chloro, bromo, —CN, —CF 3 , —OR 5 , —SR c , —NR 6 R 7 , —C 3-6 cycloalkyl or spiro-C 3-6 cycloalkyl,

(b) —CH 2 -phenyl unsubstituted or substituted with one, two or three of fluoro, chloro, bromo, —OR 4 , —SR, —NR 6 R 7 or —C 1-3 alkyl,

(c) —C 3-8 cycloalkyl unsubstituted or substituted with one, two or three of fluoro, chloro, bromo, —OR 4 , —SR, —NR 6 R 7 or —C 1-3 alkyl,

(d) aryl unsubstituted or substituted with one, two or three of fluoro, chloro, bromo, —OR 4 ,

—SR, —NR 6 R 7 or —C 1-3 alkyl,

(e) —C 1-5 alkyl-X—C 1-5 alkyl wherein X is O, S or NH,

(f) heteroaryl unsubstituted or substituted with one, two or three of fluoro, chloro, bromo, —OR 4 , —SR, —NR 6 R 7 or —C 1-3 alkyl, or

(g) a heterocyclic ring unsubstituted or substituted with one, two or three of fluoro, chloro, bromo, —OR 4 , —SR, —NR 6 R 7 or —C 1-3 alkyl;

R is —H, —CF 3 , —C 1-3 alkyl or —C 3-6 cycloalkyl;

R c is —H, —CF 3 or —C 3-6 cycloalkyl;

R 4 is —H, —CF 3 , —C 1-3 alkyl or —C 3-6 cycloalkyl;

R 5 is —H, —CF 3 or C 3-6 cycloalkyl;

R 6 is —H, —C 1-3 alkyl or —C 3-6 cycloalkyl;

R 7 is —H, —C 1-3 alkyl or —C 3-6 cycloalkyl;

R 8 is —H or —C 1-3 alkyl;

R 9 is —H, —C 1-6 alkyl or —C 1-6 alkyl substituted with 1 to 3 of F;

R 10 is —H, —C 1-6 alkyl or —C 1-6 alkyl substituted with 1 to 3 of F;

or R 9 and R 10 are joined together with the carbon to which they are both attached to form spiro-C 3-6 cycloalkyl;

R a is halo, —CN, —C 1-6 alkyl, —C 1-6 alkyl substituted with 1 to 3 of F, —OC 1-6 alkyl or —OC 1-6 alkyl substituted with 1 to 3 of F; and

R b is —H, halo, —CN, —C 1-6 alkyl, —C 1-6 alkyl substituted with 1 to 3 of F, —OC 1-6 alkyl or —OC 1-6 alkyl substituted with 1 to 3 of F.

2. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein R 1 and R 2 are each independently selected from —C 1-4 alkyl, or R 1 and R 2 are joined together with the carbon to which they are both attached to form spiro-C 3-6 cycloalkyl.

3. The compound of claim 2 or a pharmaceutically acceptable salt thereof wherein R 1 and R 2 are the same moiety selected from —C 1-4 alkyl, or R 1 and R 2 are joined together with the carbon to which they are both attached to form spiro-C 3-6 cycloalkyl.

4. The compound of claim 2 or a pharmaceutically acceptable salt thereof wherein R 9 and R 10 are each independently —H, —C 1-3 alkyl or —C 1-3 alkyl substituted with 1 to 3 of F, or R 9 and R 10 are joined together with the carbon to which they are both attached to form spiro-C 3-6 cycloalkyl.

5. The compound of claim 4 or a pharmaceutically acceptable salt thereof wherein R 9 and R 10 are each independently —H, —CH 3 or —CF 3 , or R 9 and R 10 are joined together with the carbon to which they are both attached to form spiro-C 3-6 cycloalkyl.

6. The compound of claim 5 or a pharmaceutically acceptable salt thereof wherein R 9 and R 10 are the same moiety selected from —C 1-6 alkyl.

7. The compound of claim 2 or a pharmaceutically acceptable salt thereof wherein R a is halo, —CN, —C 1-3 alkyl, —C 1-3 alkyl substituted with 1 to 3 of F,

—OC 1-3 alkyl or —OC 1-3 alkyl substituted with 1 to 3 of F.

8. The compound of claim 7 or a pharmaceutically acceptable salt thereof wherein R b is —H, halo, —CN, —C 1-3 alkyl, —C 1-3 alkyl substituted with 1 to 3 of F, —OC 1-3 alkyl or —OC 1-3 alkyl substituted with 1 to 3 of F.

9. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein R 3 is:

(a) —C 1-8 alkyl, —CH 2 CH 2 OH, —CH 2 CH 2 CH 2 OH, —CH 2 CH 2 SH, —CH 2 CH 2 CH 2 SH, —CH 2 CH 2 NH 2 , —CH 2 CH 2 CH 2 NH 2 ,

(b) —CH 2 -phenyl, unsubstituted or substituted with one, two or three substituents independently selected from fluoro, chloro, bromo, —OR 4 , —SR, —NR 6 R 7 or —C 1-3 alkyl,

(c) —C 3-6 cycloalkyl, unsubstituted or substituted with one, two or three substituents independently selected from fluoro, chloro, bromo, —OR 4 , —SR —NR 6 R 7 or —C 1-3 alkyl,

(d) phenyl or naphthyl, each unsubstituted or substituted with one, two or three substituents independently selected from fluoro, chloro, bromo, —OR 4 , —NR 6 R 7 or

—C 1-3 alkyl,

(e) —CH 2 CH 2 OCH 3 , —CH 2 CH 2 OCH 2 CH 3 , —CH 2 CH 2 CH 2 OCH 3 , —CH 2 CH 2 CH 2 OCH 2 CH 3 ,

—CH 2 CH 2 SCH 3 , —CH 2 CH 2 SCH 2 CH 3 , —CH 2 CH 2 CH 2 SCH 3 , —CH 2 CH 2 CH 2 SCH 2 CH 3

—CH 2 CH 2 NHCH 3 , —CH 2 CH 2 NHCH 2 CH 3 , —CH 2 CH 2 CH 2 NHCH 3 , or

—CH 2 CH 2 CH 2 NHCH 2 CH 3 ;

(f) pyridyl, unsubstituted or substituted with one, two or three substituents independently selected from fluoro, chloro, bromo, OR 4 , —SR, —NR 6 R 7 or —C 1-3 alkyl, or

(g) piperidinyl, pyrrolidinyl, tetrahydrofuranyl, or tetrahydropyranyl, each unsubstituted or substituted with one, two or three substituents independently selected from fluoro, chloro, bromo, OR 4 , —SR, —NR 6 R 7 or —C 1-3 alkyl.

10. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein R 3 is —C i-8 alkyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or —C 1-3 alkyl-O—C 1-3 alkyl.

11. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein R 3 is —C 1-6 alkyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

12. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein:

R 1 and R 2 are both methyl, ethyl, propyl or i-propyl;

R 3 is —C 1-6 alkyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl;

R 8 is —H or —C 1-3 alkyl;

R 9 is —H, —C 1-3 alkyl or —C 1-3 alkyl substituted with 1 to 3 of F;

R 10 is —H, —C 1-3 alkyl or —C 1-3 alkyl substituted with 1 to 3 of F;

or R 9 and R 10 are joined together with the carbon to which they are both attached to form spiro-C 3-6 cycloalkyl;

R a is halo, —CN, —C 1-3 alkyl, —C 1-3 alkyl substituted with 1 to 3 of F, —OC 1-3 alkyl or —OC 1-3 alkyl substituted with 1 to 3 of F; and

Rb is —H, halo, —CN, —C 1-3 alkyl, —C 1-3 alkyl substituted with 1 to 3 of F, —OC 1-3 alkyl or —OC 1-3 alkyl substituted with 1 to 3 of F.

13. The compound of claim 1 that is

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-chlorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-chlorophenyl)ethyl)(methyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-chlorophenyl)ethyl)(methyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-3-(6-amino-9H-purin-9-yl)-1,1,1-trifluoropropan-2-yl)oxy)methyl)(((R)-2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-3-(6-amino-9H-purin-9-yl)-1,1,1-trifluoropropan-2-yl)oxy)methyl)(((R)-2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((4-isopropylbenzyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((4-isopropylbenzyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((4-cyanobenzyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((4-cyanobenzyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((4-(trifluoromethoxy)benzyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((4-(trifluoromethoxy)benzyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((3-fluorobenzyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((3-fluorobenzyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(3-fluorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(3-fluorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(3-fluorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(3-fluorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(4-(trifluoromethyl)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(4-(trifluoromethyl)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-(((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-(trifluoromethyl)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-(trifluoromethyl)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(4-chlorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(4-chlorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(4-methoxyphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(4-methoxyphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-methoxyphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-methoxyphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(p-tolyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(p-tolyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-(((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(2-methoxyphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(2-methoxyphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(p-tolyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(p-tolyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(2-methoxyphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(2-methoxyphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(2-methyl-4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(2-methyl-4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-2,2,2-trifluoro-1-(3-fluorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-2,2,2-trifluoro-1-(3-fluorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-cyanophenyl)-2,2,2-trifluoroethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-cyanophenyl)-2,2,2-trifluoroethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(4-cyanophenyl)-2,2,2-trifluoroethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(4-cyanophenyl)-2,2,2-trifluoroethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-2,2,2-trifluoro-1-(3-methoxyphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-2,2,2-trifluoro-1-(3-methoxyphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-2,2,2-trifluoro-1-(p-tolyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-2,2,2-trifluoro-1-(p-tolyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-2,2,2-trifluoro-1-(3-methoxyphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-2,2,2-trifluoro-1-(3-methoxyphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-chloro-2-methylphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl) (((R)-1-(4-chloro-2-methylphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(4-chloro-2-methylphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((S)-1-(4-chloro-2-methylphenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-cyanophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-cyanophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((4-isopropylbenzyl)(methyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((4-isopropylbenzyl)(methyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(methyl((R)-1-(4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

propyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(methyl((R)-1-(4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

isopropyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

isopropyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-(trifluoromethoxy)phenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

isopropyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-chlorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

isopropyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-chlorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

isopropyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((2-(4-chlorophenyl)propan-2-yl)amino)phosphoryl)amino)-2-methylpropanoate;

isopropyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((2-(4-chlorophenyl)propan-2-yl)amino)phosphoryl)amino)-2-methylpropanoate;

isopropyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((1-(4-chlorophenyl)cyclopropyl)amino)phosphoryl)amino)-2-methylpropanoate; or

isopropyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)((1-(4-chlorophenyl)cyclopropyl)amino)phosphoryl)amino)-2-methylpropanoate;

or a pharmaceutically acceptable salt thereof.

14. The compound of claim 13 , selected from:

isopropyl 2-(((R)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl)(((R)-1-(4-chlorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate; or

isopropyl 2-(((S)-((((R)-1-(6-amino-9H-purin-9-yl)propan-2-yl)oxy)methyl) (((R)-1-(4-chlorophenyl)ethyl)amino)phosphoryl)amino)-2-methylpropanoate;

or a pharmaceutically acceptable salt thereof.

15. A pharmaceutical composition comprising an effective amount of the compound according to claim 1 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

16. The pharmaceutical composition of claim 15 further comprising an effective amount of one or more additional HIV antiviral agent selected from HIV protease inhibitors, HIV integrase inhibitors, non-nucleoside HIV reverse transcriptase inhibitors, nucleoside HIV reverse transcriptase inhibitors, HIV fusion inhibitors and HIV entry inhibitors.

17. The pharmaceutical composition of claim 15 further comprising an effective amount of one or more additional HIV antiviral agent selected from:

abacavir, abacavir sulfate, abacavir+lamivudine, abacavir+lamivudine+zidovudine, amprenavir, atazanavir, atazanavir sulfate, AZT, capravirine, darunavir, dideoxycytidine, dideoxyinosine, delavirdine, delavirdine mesylate, dolutegravir, doravirine, efavirenz, 4′-ethynyl-2-fluoro-2′-deoxyadenosine, elvitegravir, emtricitabine, emivirine, enfuvirtide, etravirine, fosamprenavir calcium, indinavir, indinavir sulfate, lamivudine, lamivudine+zidovudine, lopinavir, lopinavir+ritonavir, maraviroc, nelfinavir, nelfinavir mesylate, nevirapine, PPL-100, raltegravir, rilpivirine, ritonavir, saquinavir, saquinavir mesylate, stavudine, tipranavir, or vicriviroc.

18. A method for the prophylaxis or treatment of infection by HIV or for the prophylaxis, treatment, or delay in the onset of AIDS in a subject in need thereof which comprises administering to the subject an effective amount of the compound according to claim 1 , or a pharmaceutically acceptable salt thereof.

19. The method of claim 18 further comprising administering to the subject an effective amount of one or more additional HIV antiviral agent selected from HIV protease inhibitors, HIV integrase inhibitors, non-nucleoside HIV reverse transcriptase inhibitors, nucleoside HIV reverse transcriptase inhibitors, HIV fusion inhibitors and HIV entry inhibitors.

20. The method of claim 18 further comprising administering to the subject an effective amount of one or more additional HIV antiviral agent selected from:

abacavir, abacavir sulfate, abacavir+lamivudine, abacavir+lamivudine+zidovudine, amprenavir, atazanavir, atazanavir sulfate, AZT, capravirine, darunavir, dideoxycytidine, dideoxyinosine, delavirdine, delavirdine mesylate, dolutegravir, doravirine, efavirenz, ′-ethynyl-2-fluoro-2′-deoxyadenosine, elvitegravir, emtricitabine, emivirine, enfuvirtide, etravirine, fosamprenavir calcium, indinavir, indinavir sulfate, lamivudine, lamivudine+zidovudine, lopinavir, lopinavir+ritonavir, maraviroc, nelfinavir, nelfinavir mesylate, nevirapine, PPL-100, raltegravir, rilpivirine, ritonavir, saquinavir, saquinavir mesylate, stavudine, tipranavir, or vicriviroc.