Compounds

1. A compound of formula (I):

wherein;

R 1 is C 1-8 alkylamino, C 1-8 alkoxy, C 3-7 cycloalkylC 1-6 alkylamino, C 3-7 cycloalkylC 1-6 alkoxy, C 1-3 alkoxyC 2-3 alkoxy, or Het b -C 1-3 alkoxy;

Het b is a 5- or 6-membered saturated aliphatic heterocyle containing one oxygen atom;

R 2 is —(CH 2 ) n -Het;

n is an integer having a value of 1 to 4;

Het is a 5- or 6-membered saturated aliphatic heterocycle containing one oxygen heteroatom, which heterocycle may be substituted by one or two C 1-4 alkyl groups;

or salts or solvates thereof.

2. A compound according to claim 1 wherein R 1 is C 1-6 alkylamino, C 1-8 alkoxy, C 3-7 cycloalkylC 1-6 alkylamino, C 3-7 cycloalkylC 1-6 alkoxy, C 1-3 alkoxyC 2-3 alkoxy, or Het b -C 1-3 alkoxy.

3. A compound according to claim 1 or claim 2 wherein R 1 is n-butoxy, n-butylamino, 2,2-dimethylpentyloxy, n-pentylamino, 3-methylbutoxy, 2-methylbutoxy, 1-methylbutoxy, 2-methylbutylamino, 3-methylbutylamino, 1-methylbutylamino, 2-(cyclopropyl)ethoxy, 2-(ethoxy)ethoxy, (1-methyl-2-methoxy)ethoxy, cyclohexylmethylamino, cyclopentylmethylamino, 2-(cyclopropyl)ethylamino, 2-(methyl)propoxy, cyclohexylmethoxy, methoxyethoxy, (2-tetrahydrofuranyl)methoxy, (2-tetrahydro-2H-pyranyl)methoxy, or 2-(iso-propoxy)ethoxy.

4. A compound according to claim 1 wherein n is 1.

5. A compound according to claim 1 wherein n is 2.

6. A compound according to claim 1 wherein n is 3.

7. A compound according to claim 1 wherein n is 4.

8. A compound according to claim 1 wherein n is 1 and Het is tetrahydrofuran-3-yl, tetrahydro-2H-pyran-3-yl, tetrahydro-2H-pyran-4-yl, tetrahydrofuran-2-yl, 2,2-dimethyltetrahydro-2H-pyran-4-yl, or tetrahydro-2H-pyran-2-yl.

9. A compound according to claim 1 wherein n is 2 and Het is tetrahydro-2H-pyran-4-yl, tetrahydrofuran-2-yl, tetrahydro-2H-pyran-3-yl, tetrahydro-2H-pyran-2-yl, or tetrahydrofuran-3-yl.

10. A compound according to claim 1 wherein n is 3 and Het is tetrahydro-2H-pyran-3-yl.

11. A compound according to claim 1 wherein n is 4 and Het is tetrahydro-2H-pyran-3-yl.

12. A compound according to claim 1 wherein R 1 is n-butylamino, n-butoxy, or 2-(cyclopropyl)ethoxy.

13. A compound according to claim 1 wherein n is 1 and R 2 is tetrahydro-2H-pyran-4-yl or tetrahydrofuran-3-yl.

14. A compound according to claim 1 wherein R 1 is n-butylamino, n-butoxy, (R)-1-methyl butyloxy, (S)-1-methylbutyloxy, or 2-(cyclopropyl)ethoxy.

15. A compound according to claim 1 wherein Het is tetrahydrofuran-3-yl, tetrahydro-2H-pyran-3-yl, tetrahydro-2H-pyran-4-yl, tetrahydrofuran-2-yl, 2,2-dimethyltetrahydro-2H-pyran-4-yl, or tetrahydro-2H-pyran-2-yl.

16. A compound according to claim 1 wherein Het is tetrahydro-2H-pyran-4-yl, tetrahydrofuran-2-yl, tetrahydro-2H-pyran-3-yl, tetrahydro-2H-pyran-2-yl, or tetrahydrofuran-3-yl.

17. A compound according to claim 1 wherein Het is tetrahydro-2H-pyran-3-yl.

18. A compound according to claim 1 wherein Het is tetrahydro-2H-pyran-3-yl.

19. A compound according to claim 1 wherein Het is tetrahydro-2H-pyran-4-yl, tetrahydro-2H-pyran-3-yl, tetrahydro-2H-pyran-2-yl, 2,2-dimethyltetrahydro-2H-pyran-4-yl, tetrahydrofuran-3-yl, or tetrahydro-2H-pyran-2-yl.

20. A compound according to claim 1 wherein n is 2 and Het is tetrahydro-2H-pyran-4-yl, tetrahydro-2H-pyran-3-yl, tetrahydro-2H-pyran-2-yl, 2,2-dimethyltetrahydro-2H-pyran-4-yl, tetrahydrofuran-3-yl, or tetrahydrofuran-2-yl.

21. A compound according to claim 1 wherein n is 3 and Het is tetrahydro-2H-pyran-4-yl, tetrahydro-2H-pyran-3-yl, tetrahydro-2H-pyran-2-yl, 2,2-dimethyltetrahydro-2H-pyran-4-yl, tetrahydrofuran-3-yl, or tetrahydrofuran-2-yl.

22. A compound according to claim 1 wherein n is 4 and Het is tetrahydro-2H-pyran-4-yl, tetrahydro-2H-pyran-3-yl, tetrahydro-2H-pyran-2-yl, 2,2-dimethyltetrahydro-2H-pyran-4-yl, tetrahydrofuran-3-yl, or tetrahydrofuran-2-yl.

23. A compound selected from the list consisting of:

6-amino-2-butoxy-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-butoxy-9-(tetrahydro-2H-pyran-2-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-butoxy-9-(tetrahydrofuran-2-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-butylamino-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-butylamino-9-(tetrahydro-2H-pyran-2-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-butylamino-9-(tetrahydrofuran-2-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-butylamino-9-[2-(tetrahydro-2H-pyran-4-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-butylamino-9-(tetrahydrofuran-3-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-butylamino-9-(tetrahydro-2H-pyran-3-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-butoxy-9-(tetrahydrofuran-3-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-butoxy-9-[2-(tetrahydro-2H-pyran-4-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-butoxy-9-(tetrahydro-2H-pyran-3-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-butoxy-9-[2-(tetrahydrofuran-2-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-butylamino-9-[2-(tetrahydrofuran-2-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-butoxy-9-[2-(tetrahydro-2H-pyran-3-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-butylamino-9-[2-(tetrahydro-2H-pyran-3-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2,2-dimethylpentyl)oxy]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-(pentylamino)-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(3-methylbutyl)oxy]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-methylbutyl)oxy]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(1-methylbutyl)oxy]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-methylbutyl)amino]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(3-methylbutyl)amino]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(1-methylbutyl)amino]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-(tetrahydro-3-furanylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-butyloxy-9-[2-(tetrahydro-2H-pyran-2-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-butyloxy-9-[(2,2-dimethyltetrahydro-2H-pyran-4-yl)methyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[(2,2-dimethyltetrahydro-2H-pyran-4-yl)methyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-butyloxy-9-[2-(tetrahydro-3-furanyl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[2-(tetrahydro-2H-pyran-2-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[2-(tetrahydro-3-furanyl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-(tetrahydro-3-furanylmethyl)-7,9-dihydro-8H-purin-8-one, isomer 1;

6-amino-2-{[2-(ethyloxy)ethyl]oxy}-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[1-methyl-2-(methoxy)ethyl]oxy}-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[2-(ethyloxy)ethyl]oxy}-9-(tetrahydro-2H-pyran-3-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[1-methyl-2-(methoxy)ethyl]oxy}-9-(tetrahydro-2H-pyran-3-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(cyclohexylmethyl)amino]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(cyclopentylmethyl)amino]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)amino]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-(tetrahydro-3-furanylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-methylpropyl)oxy]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(cyclohexyl methyl)oxy]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[2-(methoxy)ethyl]oxy}-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[2-(methoxy)ethyl]oxy}-9-(tetrahydro-3-furanylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(tetrahydro-2-furanylmethyl)oxy]-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[3-(tetrahydro-2H-pyran-3-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-9-(tetrahydro-2H-pyran-4-ylmethyl)-2-[(tetrahydro-2H-pyran-2-yl methoxy]-7,9-dihydro-8H-purin-8-one;

6-amino-2-({2-[(1-methylethyl)oxy]ethyl}oxy)-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[4-(tetrahydro-2H-pyran-3-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)amino]-9-(tetrahydro-3-furanylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)amino]-9-(tetrahydro-2H-pyran-3-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-(tetrahydro-3-furanylmethyl)-7,9-dihydro-8H-purin-8-one;

and salts or solvates thereof.

24. A compound selected from the list consisting of:

6-amino-2-(butyloxy)-9-(tetrahydro-3-furanylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-butylamino-9-(tetrahydro-2H-pyran-4-ylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-(tetrahydro-3-furanylmethyl)-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-(tetrahydro-3-furanylmethyl)-7,9-dihydro-8H-purin-8-one;

and salts or solvates thereof.

25. A compound selected from the list consisting of:

6-amino-2-butoxy-9-[2-(tetrahydrofuran-2-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-butylamino-9-[2-(tetrahydro-2H-pyran-3-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-butyloxy-9-[2-(tetrahydro-2H-pyran-2-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-butyloxy-9-[(2,2-dimethyltetrahydro-2H-pyran-4-yl)methyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[3-(tetrahydro-2-furanyl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[4-(tetrahydro-2-furanyl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-{2-[(3S)-tetrahydro-3-furanyl]ethyl}-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-{2-[(3R)-tetrahydro-3-furanyl]ethyl}-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[3-(tetrahydro-3-furanyl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[4-(tetrahydro-3-furanyl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[3-(tetrahydro-2H-pyran-2-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[4-(tetrahydro-2H-pyran-2-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[3-(tetrahydro-2H-pyran-4-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[4-(tetrahydro-2H-pyran-4-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[2-(2,2-dimethyltetrahydro-2H-pyran-4-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[3-(2,2-dimethyltetrahydro-2H-pyran-4-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butylamino)-9-[4-(2,2-dimethyltetrahydro-2H-pyran-4-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[3-(tetrahydro-2-furanyl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[4-(tetrahydro-2-furanyl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-{2-[(3S)-tetrahydro-3-furanyl]ethyl}-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-{2-[(3R)-tetrahydro-3-furanyl]ethyl}-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[3-(tetrahydro-3-furanyl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[4-(tetrahydro-3-furanyl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[3-(tetrahydro-2H-pyran-2-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[4-(tetrahydro-2H-pyran-2-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[3-(tetrahydro-2H-pyran-3-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[4-(tetrahydro-2H-pyran-3-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[3-(tetrahydro-2H-pyran-4-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[4-(tetrahydro-2H-pyran-4-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[2-(2,2-dimethyltetrahydro-2H-pyran-4-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[3-(2,2-dimethyltetrahydro-2H-pyran-4-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9-[4-(2,2-dimethyltetrahydro-2H-pyran-4-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[2-(tetrahydro-2-furanyl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[3-(tetrahydro-2-furanyl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[4-(tetrahydro-2-furanyl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[2-(tetrahydro-3-furanyl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-{2-[(3S)-tetrahydro-3-furanyl]ethyl}-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-{2-[(3R)-tetrahydro-3-furanyl]ethyl}-7,9-dihydro-8H-purin-8-one

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[3-(tetrahydro-3-furanyl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[4-(tetrahydro-3-furanyl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[2-(tetrahydro-2H-pyran-2-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[3-(tetrahydro-2H-pyran-2-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[4-(tetrahydro-2H-pyran-2-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[2-(tetrahydro-2H-pyran-3-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[4-(tetrahydro-2H-pyran-3-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[2-(tetrahydro-2H-pyran-4-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[3-(tetrahydro-2H-pyran-4-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[4-(tetrahydro-2H-pyran-4-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[2-(2,2-dimethyltetrahydro-2H-pyran-4-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[3-(2,2-dimethyltetrahydro-2H-pyran-4-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[4-(2,2-dimethyltetrahydro-2H-pyran-4-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[2-(tetrahydro-2-furanyl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[3-(tetrahydro-2-furanyl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-{2-[(3S)-tetrahydro-3-furanyl]ethyl}-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-{2-[(3R)-tetrahydro-3-furanyl]ethyl}-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[3-(tetrahydro-3-furanyl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[4-(tetrahydro-3-furanyl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[2-(tetrahydro-2H-pyran-2-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[3-(tetrahydro-2H-pyran-2-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[4-(tetrahydro-2H-pyran-2-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[2-(tetrahydro-2H-pyran-3-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[4-(tetrahydro-2H-pyran-3-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[2-(tetrahydro-2H-pyran-4-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[3-(tetrahydro-2H-pyran-4-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[4-(tetrahydro-2H-pyran-4-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-9-[2-(2,2-dimethyltetrahydro-2H-pyran-4-yl)ethyl]-2-{[(S)-1-methylbutyl]oxy}-7,9-dihydro-8H-purin-8-one;

6-amino-9-[3-(2,2-dimethyltetrahydro-2H-pyran-4-yl)propyl]-2-{[(1S)-1-methylbutyl]oxy}-7,9-dihydro-8H-purin-8-one;

6-amino-9-[4-(2,2-dimethyltetrahydro-2H-pyran-4-yl)butyl]-2-{[(1S)-1-methylbutyl]oxy}-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-[2-(tetrahydro-2-furanyl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-[3-(tetrahydro-2-furanyl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-{2-[(3S)-tetrahydro-3-furanyl]ethyl}-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-{2-[(3R)-tetrahydro-3-furanyl]ethyl}-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-[3-(tetrahydro-3-furanyl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-[4-(tetrahydro-3-furanyl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-[2-(tetrahydro-2H-pyran-2-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-[3-(tetrahydro-2H-pyran-2-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-[4-(tetrahydro-2H-pyran-2-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-[2-(tetrahydro-2H-pyran-3-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-[4-(tetrahydro-2H-pyran-3-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-[2-(tetrahydro-2H-pyran-4-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-[3-(tetrahydro-2H-pyran-4-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1R)-1-methylbutyl]oxy}-9-[4-(tetrahydro-2H-pyran-4-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-9-[2-(2,2-dimethyltetrahydro-2H-pyran-4-yl)ethyl]-2-{[(1R)-1-methylbutyl]oxy}-7,9-dihydro-8H-purin-8-one;

6-amino-9-[3-(2,2-dimethyltetrahydro-2H-pyran-4-yl)propyl]-2-{[(1R)-1-methylbutyl]oxy}-7,9-dihydro-8H-purin-8-one;

6-amino-9-[4-(2,2-dimethyltetrahydro-2H-pyran-4-yl)butyl]-2-{[(1R)-1-methylbutyl]oxy}-7,9-dihydro-8H-purin-8-one;

and salts and solvates thereof.

26. A method for the treatment of asthma, which method comprises administering an effective amount of a compound as defined in claim 1 , or a pharmaceutically acceptable salt or solvate thereof.

27. A pharmaceutical composition comprising a compound as defined in claim 1 , or a pharmaceutically acceptable salt or solvate thereof, and optionally one or more pharmaceutically acceptable diluents or carriers.

28. A compound selected from the list consisting of:

6-amino-2-(butyloxy)-9[4-(tetrahydro-2H-pyran-3-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9[3-(tetrahydro-2H-pyran-4-yl)propyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-(butyloxy)-9[4-(tetrahydro-2H-pyran-4-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[3-(tetrahydro-2H-pyran-4-yl)propyl]-7, 9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[2-(tetrahydro-2H-pyran-4-yl)ethyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[3-(tetrahydro-2H-pyran-4-yl)propyl]-7,9-dihydro-8H-purin-8-one, and;

6-amino-2-{[(1S)-1-methylbutyl]oxy}-9-[4-(tetrahydro-2H-pyran-4-yl)butyl]-7,9-dihydro-8H-purin-8-one;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[2-(tetrahydro-2H-pyran-4-yl)ethyl]-7, 9-dihydro-8H-purin-8-one, and;

6-amino-2-[(2-cyclopropylethyl)oxy]-9-[4-(tetrahydro-2H-pyran-4-yl)butyl]-7,9-dihydro-8H-purin-8-one;

and salts or solvates thereof.