Imidazo[1,2-α]pyridine ether compounds as ion channel modulators

1. A method for treating a disease or condition caused by defective or inadequate function of an ion channel in a human, wherein the method comprises administering to a human in need thereof, an effective amount of a compound of formula (I), or a pharmaceutically acceptable salt, ester, amide, complex, chelate, solvate, stereoisomer, stereoisomeric mixture, geometric isomer, crystalline or amorphous form, thereof:

wherein, independently at each occurrence,

n is selected from 0, 1, 2 and 3; X is selected from a direct bond, —C(R 3 )═CH—, and —C(R 4 , R 5 )—Y—;

Y is selected from a direct bond, O, S, and C 1 –C 4 alkylene;

R 2 , R 15 , R 16 and R 18 are independently selected from bromine, chlorine, fluorine, carboxy, hydrogen, hydroxy, hydroxymethyl, methanesulfonamido, nitro, sulfamyl, cyano, CHF 2 , CH 2 F, CF 3 , C 2 –C 7 alkanoyloxy, C 1 –C 6 alkyl, C 3 –C 8 cycloalkyl, phenyl, naphthyl, benzyl, C 1 –C 6 alkoxy, C 2 –C 7 alkoxycarbonyl, C 1 –C 6 thioalkyl, CH 2 N(R 13 , R 14 ) and N(R 13 , R 14 ) where R 13 and R 14 are independently selected from hydrogen, acetyl, methanesulfonyl, and C 1 –C 6 alkyl, or R 2 and R 16 , when taken together with the carbon to which they are attached, may form a C 4 –C 7 cycloalkyl;

R 3 is selected from hydrogen, C 1 –C 6 alkyl, C 3 –C 8 cycloalkyl, phenyl, naphthyl, and benzyl;

R 1 , R 4 and R 5 are independently selected from hydrogen, C 1 –C 6 alkyl, phenyl, naphthyl, and benzyl, or R 4 and R 5 , when taken together with the carbon to which they are attached, may form a spiro C 3 –C 5 cycloalkyl;

A is selected from C 5 –C 12 alkyl, a C 3 –C 13 carbocyclic ring, and ring systems selected from formulae (II), (III), (IV), (V), (VI) and (VII):

where R 6 , R 7 and R 8 are independently selected from bromine, chlorine, fluorine, carboxy, hydrogen, hydroxy, hydroxymethyl, methanesulfonamido, nitro, sulfamyl, trifluoromethyl, C 2 –C 7 alkanoyloxy, C 1 –C 6 alkyl, C 1 –C 6 alkoxy, C 2 –C 7 alkoxycarbonyl, C 1 –C 6 thioalkyl, phenyl, naphthyl, and N(R 13 ,R 14 ) where R 13 and R 14 are independently selected from hydrogen, acetyl, methanesulfonyl, and C 1 –C 6 alkyl;

where R 10 and R 11 are independently selected from bromine, chlorine, fluorine, carboxy, hydrogen, hydroxy, hydroxymethyl, methanesulfonamido, nitro, sulfamyl, trifluoromethyl, C 2 –C 7 alkanoyloxy, C 1 –C 6 alkyl, C 1 –C 6 alkoxy, C 2 –C 7 alkoxycarbonyl, C 1 –C 6 thioalkyl, phenyl, naphthyl, and N(R 13 ,R 14 ) where R 13 and R 14 are independently selected from hydrogen, acetyl, methanesulfonyl, and C 1 –C 6 alkyl;

where R 12 is selected from bromine, chlorine, fluorine, carboxy, hydrogen, hydroxy, hydroxymethyl, methanesulfonamido, nitro, sulfamyl, trifluoromethyl, C 2 –C 7 alkanoyloxy, C 1 –C 6 alkyl, C 1 –C 6 alkoxy, C 2 –C 7 alkoxycarbonyl, C 1 –C 6 thioalkyl, cyano, phenyl, naphthyl, and N(R 13 ,R 14 ) where R 13 and R 14 are independently selected from hydrogen, acetyl, methanesulfonyl, and C 1 –C 6 alkyl; and Z is selected from CH, CH 2 , O, N and S, where Z is directly bonded to “X” as shown in formula (I) when Z is CH, or Z is directly bonded to R 9 or “X” as shown in formula (I) when Z is N, and R 9 is selected from hydrogen, C 1 –C 6 alkyl, C 3 –C 8 cycloalkyl, phenyl, naphthyl, and benzyl;

wherein the disease or condition is selected from the group consisting of arrhythmia, atrial or supraventricular arrhythmia, ventricular arrhythmia, atrial fibrillation, ventricular fibrillation, atrial flutter and ventricular flutter.

2. The method of claim 1 , wherein n is 2.

3. The method of claim 1 wherein the compound of formula (I), or a pharmaceutically acceptable salt, ester, amide, complex, chelate, solvate, stereoisomer, stereoisomeric mixture, geometric isomer, crystalline or amorphous form, thereof; is a compound of formula (I) wherein X is —C(R 4 ,R 5 )—Y—, and R 4 and R 5 , when taken together with the carbon to which they are attached form a spiro C 3 –C 5 cycloalkyl.

4. The method of claim 3 wherein the compound of formula (I) is a compound of formula (I) wherein Y is a direct bond.

5. The method of claim 4 wherein the compound of formula (I) is a compound of formula (I) wherein R 4 and R 5 , when taken together with the carbon to which they are attached form a spiro C 3 cycloalkyl.

6. The method of claim 1 wherein the compound of formula (I) is a compound of formula (I), or a pharmaceutically acceptable salt, ester, amide, complex, chelate, solvate, stereoisomer, stereoisomeric mixture, geometric isomer, crystalline or amorphous form, thereof; wherein A is selected from formula (V); and Z is N or S.

7. The method of claim 6 wherein a compound of formula (I) is a compound of formula (I) wherein X is a direct bond or —C(R 4 ,R 5 )—Y—.

8. The method of claim 1 wherein said ion channel is a potassium channel.

9. The method of claim 8 wherein said potassium channel is a voltage-activated potassium channel.

10. The method of claim 9 wherein said voltage-activated potassium channel is responsible for Kv1.3, Kv1.5 or HERG currents.

11. The method of claim 1 wherein said ion channel is responsible for one or more cardiac early repolarizing currents comprising ionic currents which activate rapidly after membrane depolarization and which effect repolarization of the cell.

12. The method of claim 11 wherein said early repolarizing currents comprise the cardiac transient outward potassium current (I to ) and/or the ultrarapid delayed rectifier current (I Kur ).

13. The method of claim 12 wherein the cardiac transient outward potassium current (I to ) and/or the ultrarapid delayed rectifier current (I Kur ) comprise at least one of the Kv4.2, Kv4.3, Kv2.1, Kv1.4 and Kv1.5 currents.

14. The method of claim 1 wherein said ion channel is a cardiac potassium channel responsible for Kv1.5 currents.

15. The method of claim 1 wherein said ion channel is responsible for one or more neuronal early repolarizing currents comprising ionic currents which activate rapidly after membrane depolarization and which effect repolarization of the cell.

16. The method of claim 15 wherein the early repolarizing currents comprise the neuronal transient outward potassium current (I A ) and/or the ultrarapid delayed rectifier current (I Kur ).

17. The method of claim 16 wherein the neuronal transient outward potassium current (I A ) and/or the ultrarapid delayed rectifier current (I Kur ) comprise at least one of the Kv4.2, Kv4.3, Kv2.1, Kv1.4 and Kv1.5 currents.

18. The method of claim 1 wherein said ion channel is a neuronal potassium channel responsible for Kv1.5 currents.

19. The method of claim 1 wherein said ion channel is a sodium channel.

20. The method of claims 19 wherein said sodium channel is a voltage-activated sodium channel.

21. The method of claims 20 wherein said voltage-activated sodium channel is one of the Na v 1, Na v 2 or Na v 3 series.

22. The method of claims 21 wherein said sodium channel is a ligand-activated sodium channel.

23. The method of claim 19 wherein said sodium channel is a cardiac sodium channel.

24. The method of claim 19 wherein said sodium channel is a neuronal sodium channel.

25. The method of claim 19 wherein said sodium channel is a skeletal muscle sodium channel.

26. The method of claim 19 wherein said sodium channel is a central nervous system sodium channel.

27. The method of claim 19 wherein said sodium channel is a peripheral nervous system sodium channel.

28. The method of claim 1 , wherein the condition is selected from the group consisting of atrial or supraventricular arrhythmia, atrial fibrillation, ventricular fibrillation, atrial and ventricular flutter.

29. The method of claim 28 , wherein the condition is selected from the group consisting of atrial fibrillation and atrial flutter.