Phosphoramidate, and mono-, di-, and tri-phosphate esters of (1R, cis)-4-(6-amino-9H-purin-9-yl)-2-cyclopentene-1-methanol as antiviral agents

A compound of formula (I)

• wherein:
• R1 is hydrogen;
• C6-14aryl;
• or heteroaryl, optionally substituted with one or more substituents selected from the group consisting of C1-6 alkoxy, nitro, halogen, amino, hydroxy, carboxy and esters thereof, carboxyalkyl, —CONHR6, and —CONR6R7, wherein R6 and R7, which may be the same or different, are independently selected from C1-8 alkyl, C1-8 alkylaryl or C6-14 aryl;
• R2 and R3 are independently selected from hydrogen or C1-8 alkyl, C3-8 cycloalkyl, C2-8 alkenyl, C5-8cycloalkenyl, C6-14 aryl, or aralkyl wherein each C1-8 alkyl, C3-8 cycloalkyl, C2-8 alkenyl, C5-8 cycloalkenyl, C6-14 aryl, or aralkyl may be optionally substituted with one or more substituents selected from the group consisting of C1-8 alkyl, halo, hydroxy, alkoxy, amino, aminoalkyl, —SH, heterocycle, carboxy and esters thereof, carboxyalkyl, —CONHR6, and —CONR6R7, wherein R6 and R7, which may be the same or different, are independently selected from C1-8 alkyl, C1-8 alkylaryl or C6-14 aryl;
• or R2 and R3 can together with the C atom to which these are attached form a 3 to 8-membered ring, wherin the ring members are C atoms;
• R4 is —OR8, —NR8R9 or —SR8, where R8 and R9, which may be the same or different, are independently selected from hydrogen;
• or C1-8 alkyl, C3-8 cycloalkyl, C2-8 alkenyl, C5-8 cycloalkenyl, aralkyl, heteroaryl, or C6-14 aryl wherein each C1-8 alkyl, C3-8 cycloalkyl, C2-8 alkenyl, C5-8 cycloalkenyl, aralkyl, heteroaryl, or C6-14 aryl may be optionally substituted with one or more substituents selected from the group consisting of halo, hydroxy, alkoxy, amino, aminoalkyl, —SH, carboxy and esters thereof, carboxyalkyl, —CONHR6, and —CONR6R7, wherein R6 and R7, which may be the same or different, are independently selected from C1-8 alkyl, C1-8 alkylaryl or C6-14 aryl;
• R5 is hydrogen;
• C1-8 alkyl;
• or C6-14 aryl;
• or R2 and R5 may together with the C atom and the N atom to which these are respectively attached form a 5- or 6-membered ring wherein the ring members contributed by R2/R5 are C atoms or R3 and R5 may together with the C atom and N atom to which these are respectively attached form a 5- or 6-membered ring wherein the ring members contributed by R2/R5 are C atoms;
• or a pharmaceutically acceptable salt, ester or salt of an ester of the compound of formula (I).