Pyridazin-3(2H)-One Derivatives And Their Use As Pde4 Inhibitors

• US 20090029996A1
• Filed: 06/21/2005
• Published: 01/29/2009
• Est. Priority Date: 06/21/2004
• Status: Abandoned Application

• Current Assignee: Laboratories Almirall SA (Grupo Corporativo Landon SL)
• Original Assignee: Laboratories Almirall SA (Grupo Corporativo Landon SL)
• Inventors: Warrellow, Graham, Masdeu Margalef, Maria Del Carmen, Aguilar Izquierdo, Nuria, Lumeras Amador, Wenceslao, Gracia Ferrer, Jordi, Carrascal Riera, Marta, Dal Piaz, Vittorio
• Application Number:
  US11/629,527
• Publication Number:
  US 20090029996A1
• Time in Patent Office: Days
• US Class Current: 514/236.500
• CPC Class Codes: A61P 1/00 Drugs for disorders of the alimentary tract or the digestive system
• CPC Class Codes: A61P 1/04 for ulcers, gastritis or reflux esophagitis, e.g. antacids, inhibitors of acid secretion, mucosal protectants
• CPC Class Codes: A61P 11/00 Drugs for disorders of the respiratory system
• CPC Class Codes: A61P 11/06 Antiasthmatics
• CPC Class Codes: A61P 17/00 Drugs for dermatological disorders
• CPC Class Codes: A61P 17/06 Antipsoriatics
• CPC Class Codes: A61P 19/00 Drugs for skeletal disorders
• CPC Class Codes: A61P 19/02 for joint disorders, e.g. arthritis, arthrosis
• CPC Class Codes: A61P 29/00 Non-central analgesic, antipyretic or antiinflammatory agents, e.g. antirheumatic agents; Non-steroidal antiinflammatory drugs [NSAID]
• CPC Class Codes: A61P 43/00 Drugs for specific purposes, not provided for in groups A61P1/00-A61P41/00
• CPC Class Codes: C07D 237/24 Carbon atoms having three bonds to hetero atoms with at the most one bond to halogen
• CPC Class Codes: C07D 401/12 linked by a chain containing hetero atoms as chain links
• CPC Class Codes: C07D 401/14 containing three or more hetero rings
• CPC Class Codes: C07D 405/14 containing three or more hetero rings
• CPC Class Codes: C07D 409/14 containing three or more hetero rings
• CPC Class Codes: C07D 471/04 Ortho-condensed systems
• CPC Class Codes: C07D 495/04 Ortho-condensed systems

Abstract

The invention relates to new therapeutically useful pyridazin-3(2H)-one derivatives, to processes for their preparation and to pharmaceutical compositions containing them. These compounds are potent and selective inhibitors of phosphodiesterase 4 (PDE4) and are thus useful in the treatment, prevention and suppression of related pathological conditions, diseases and disorders, in particular asthma, chronic obstructive pulmonary disease, rheumatoid arthritis, topic dermatitis, psoriasis or irritable bowel disease.

Claims

1-18. -18. (canceled)

19. A compound of formula (I)

20. A compound according to claim 19 wherein R¹ is a hydrogen atom or lower alkyl group, which is optionally substituted by one or more substituents selected from halogen atoms and hydroxy, alkoxy, alkylthio, hydroxycarbonyl and alkoxycarbonyl groups.

21. A compound according to claim 19 wherein R² is an heteroaryl group which is optionally substituted by one or more substituents selected from halogen atoms and hydroxy, lower alkyl, hydroxyalkyl, hydroxycarbonyl, alkoxy, alkylenedioxy, alkoxycarbonyl, aryloxy, acyl, acyloxy, alkylthio, arylthio, amino, nitro, cyano, mono-alkylamino, di-alkylamino, acylamino, carbamoyl, mono-alkylcarbamoyl, di-alkylcarbamoyl, difluoromethyl, trifluoromethyl, difluoromethoxy, and trifluoromethoxy groups.

22. A compound according to claim 19 wherein R² is a N-containing heteroaryl group.

23. A compound according to claim 19 wherein R² is optionally substituted by one or more substituents selected from halogen atoms and lower alkyl groups.

24. A compound according to claim 19 wherein R³ represents a group of formula:

G-L1-(CRR′

)_n—

wherein

n is an integer from 0 to 3;

R and R′

are independently selected from hydrogen atoms or lower alkyl groups;

L1 is a linker selected from a direct bond or —

CO—

, —

O(CO)—

, —

O(CO)O—

or —

(CO)O—

groups; and

G is selected from hydrogen atoms or alkyl, cycloalkyl, heterocyclyl, aryl or heteroaryl groups said groups being optionally substituted with one or more substituents selected from;

halogen atoms;

alkyl and alkenyl groups, which are optionally substituted by one or more substituents selected from halogen atoms; and

hydroxy, alkylenedioxy, alkoxy, cycloalkyloxy, alkylthio, alkylsulfinyl, alkylsulfonyl, alkylsulfamoyl, amino, mono-alkylamino, di-alkylamino, acylamino, nitro, acyl, hydroxycarbonyl, alkoxycarbonyl, carbamoyl, mono- or di-alkylcarbamoyl, ureido, N′

-alkylureido, N′

,N′

-dialkylureido, alkylsulfamido, aminosulfonyl, mono-alkylaminosulfonyl, di-alkylaminosulfonyl, cyano, difluoromethoxy, and trifluoromethoxy groups.

25. A compound according to claim 24 wherein R³ represents a group of formula:

G-L1-(CRR′

)_n—

wherein

n is an integer from 0 to 3;

R and R′

are independently selected from hydrogen atoms or methyl groups;

L1 is a linker selected from a direct bond or —

CO—

, —

O(CO)—

, —

O(CO)O—

or —

(CO)O—

groups; and

G is selected from alkyl, cycloalkyl, heterocyclyl, aryl or heteroaryl groups said groups being optionally substituted with one or more halogen atoms.

26. A compound according to claim 25 wherein R³ represents a group of formula:

G-L1-(CRR′

)_n—

wherein

n is 0 or 1

R is a hydrogen atom

R′

is a hydrogen atom or a methyl group

L1 is a linker selected from a direct bond —

O(CO)O—

or —

(CO)O—

; and

G is selected from alkyl or cycloalkyl groups said groups being optionally substituted with one halogen atom.

27. A compound according to claim 19 wherein R⁴ represents a phenyl, pyridyl, or thienyl group, which is optionally substituted by one or more substituents selected from:

halogen atoms;

alkyl groups, which are optionally substituted by one or more substituents selected from halogen atoms and hydroxy, hydroxyalkyl, alkoxy, alkylthio, mono-alkylamino, di-alkylamino, acylamino, hydroxycarbonyl, alkoxycarbonyl, carbamoyl, mono-alkylcarbamoyl, and di-alkylcarbamoyl groups; and

hydroxy, alkylenedioxy, alkoxy, cycloalkyloxy, alkylthio, alkylsulfinyl, alkylsulfonyl, alkylsulfamoyl, amino, mono- or di-alkylamino, acylamino, nitro, acyl, hydroxycarbonyl, alkoxycarbonyl, carbamoyl, mono- or di-alkylcarbamoyl, ureido, N′

-alkylureido, N′

,N′

-dialkylureido, alkylsulfamido, aminosulfonyl, mono-alkylaminosulfonyl, di-alkylaminosulfonyl, cyano, difluoromethoxy, and trifluoromethoxy groups.

28. A compound according to claim 27 wherein R⁴ is optionally substituted by one or more substituents selected from halogen atoms and lower alkyl groups.

29. A compound according to claim 28 wherein R⁴ is a phenyl group.

30. A compound according to claim 19 which is one of:

4-(methoxycarbonyl)benzyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

benzyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-(benzyloxy)-2-oxoethyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-ethoxy-2-oxoethyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-oxo-2-pyrrolidin-1-ylethyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

3-amino-3-oxopropyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-(dimethylamino)ethyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-[(tert-butoxycarbonyl)amino]ethyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-(acetyloxy)ethyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

3-fluorobenzyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

[(2,2-dimethylpropanoyl)oxy]methyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-oxo-2-pyridin-4-ylethyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-(dimethylamino)-2-oxoethyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-aminoethyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-(benzyloxy)-2-oxoethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

(butyryloxy)methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

3-oxo-1,3-dihydro-2-benzofuran-1-yl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

(acetyloxy)methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

1-(acetyloxy)ethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-(dimethylamino)-2-oxoethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

benzyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

[(2,2-dimethylpropanoyl)oxy]methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

1-(acetyloxy)-1-methylethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

[(2,2-dimethylpropanoyl)oxy]methyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

1-[(ethoxycarbonyl)oxy]ethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

2-(benzyloxy)-2-oxoethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

1-[(ethoxycarbonyl)oxy]ethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

[(2,2-dimethylpropanoyl)oxy]methyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

1-(acetyloxy)ethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

({[1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazin-4-yl]carbonyl}oxy)acetic acid;

ethyl 1-ethyl-3-(3-methylphenyl)-6-oxo-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

[(2,2-dimethylpropanoyl)oxy]methyl 1-ethyl-3-(3-methylphenyl)-6-oxo-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-3-(3-fluorophenyl)-6-oxo-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

(butyryloxy)methyl 1-ethyl-3-(3-fluorophenyl)-6-oxo-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-3-(4-fluorophenyl)-6-oxo-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

(butyryloxy)methyl 1-ethyl-3-(4-fluorophenyl)-6-oxo-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

ethyl 5-[(2-chloropyridin-3-yl)amino]-1-ethyl-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

methyl 1-ethyl-6-oxo-3-phenyl-5-(quinolin-5-ylamino)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-(acetyloxy)ethyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-[(tert-butoxycarbonyl)amino]ethyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-ethoxy-2-oxoethyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-(benzyloxy)-2-oxoethyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

benzyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-5-(4-methyloyridin-3-ylamino)-6-oxo-3-thien-2-yl-1,6-dihydropyridazin-4-carboxylate;

2-(acetyloxy)ethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-[(tert-butoxycarbonyl)amino]ethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-(acetyloxy)ethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-[(tert-butoxycarbonyl)amino]ethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-ethoxy-2-oxoethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-(benzyloxy)-2-oxoethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

benzyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-(acetyloxy)ethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-[(tert-butoxycarbonyl)amino]ethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-ethoxy-2-oxoethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-(benzyloxy)-2-oxoethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

4-fluorobenzyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

4-(methoxycarbonyl)benzyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-3-(4-methylphenyl)-6-oxo-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-5-(isoquinolin-4-ylamino)-3-(4-methylphenyl)-6-oxo-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-3-(4-methylphenyl)-5-[(4-methylpyridin-3-yl)amino]-6-oxo-1,6-dihydropyridazine-4-carboxylate;

[(2,2-dimethylpropanoyl)oxy]methyl 1-ethyl-3-(4-methylphenyl)-6-oxo-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

[(2,2-dimethylpropanoyl)oxy]methyl 1-ethyl-5-(isoquinolin-4-ylamino)-3-(4-methylphenyl)-6-oxo-1,6-dihydropyridazine-4-carboxylate;

[(2,2-dimethylpropanoyl)oxy]methyl 1-ethyl-3-(4-methylphenyl)-5-[(4-methylpyridin-3-yl)amino]-6-oxo-1,6-dihydropyridazine-4-carboxylate;

1-[(isopropoxycarbonyl)oxy]ethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

1-[(isopropoxycarbonyl)oxy]ethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

1-[(isopropoxycarbonyl)oxy]ethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

1-{[(cyclohexyloxy)carbonyl]oxy}ethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

1-{[(cyclohexyloxy)carbonyl]oxy}ethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

1-{[(cyclohexyloxy)carbonyl]oxy}ethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-6-oxo-3-phenyl-5-(thieno[2,3-c]pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-6-oxo-3-phenyl-5-(thieno[2,3-b]pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

[(2,2-dimethylpropanoyl)oxy]methyl 1-ethyl-6-oxo-3-phenyl-5-(thieno[2,3-b]pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

7-ethoxy-7-oxoheptyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

6-ethoxy-6-oxohexyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

3-amino-3-oxopropyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-ethoxy-2-oxoethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-(benzyloxy)-2-oxoethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

1-{[(1-ethylpropoxy)carbonyl]oxy}ethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

1-{[(1-ethylpropoxy)carbonyl]oxy}ethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

1-{[(1-ethylpropoxy)carbonyl]oxy}ethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

(butyryloxy)methyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

(acetyloxy)methyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

benzyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

4-(methoxycarbonyl)benzyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

(isobutyryloxy)methyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

(isobutyryloxy)methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

4-fluorobenzyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

4-(methoxycarbonyl)benzyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

[(isopropoxycarbonyl)oxy]methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

7-ethoxy-7-oxoheptyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

6-ethoxy-6-oxohexyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

4-fluorobenzyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

(5-methyl-2-oxo-1,3-dioxol-4-yl)methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

chloromethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

{[(cyclohexyloxy)carbonyl]oxy}methyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

(5-methyl-2-oxo-1,3-dioxol-4-yl)methyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

[(2,2-dimethylbutanoyl)oxy]methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

({N-[(benzyloxy)carbonyl]-L-valyl}oxy)methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

(5-methyl-2-oxo-1,3-dioxol-4-yl)methyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

ethyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

{[(cyclohexyloxy)carbonyl]oxy}methyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

{[(cyclohexyloxy)carbonyl]oxy}methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-(acetyloxy)ethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-[(tert-butoxycarbonyl)amino]ethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

{[(1-ethylpropoxy)carbonyl]oxy}methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

(isobutyryloxy)methyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

2-(acetyloxy)ethyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-[(tert-butoxycarbonyl)amino]ethyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-ethoxy-2-oxoethyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

[(isopropoxycarbonyl)oxy]methyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

2-(benzyloxy)-2-oxoethyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-ethoxy-2-oxoethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

2-(benzyloxy)-2-oxoethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

{[(1-ethylpropoxy)carbonyl]oxy}methyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

benzyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

benzyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

[(isopropoxycarbonyl)oxy]methyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

6-ethoxy-6-oxohexyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

7-ethoxy-7-oxoheptyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

({[1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazin-4-yl]carbonyl}oxy)methyl N-(tert-butoxycarbonyl)-L-leucinate;

2-methoxy-2-oxoethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

4-fluorobenzyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

4-(methoxycarbonyl)benzyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

(butyryloxy)methyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

6-ethoxy-6-oxohexyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

{[(1-ethylpropoxy)carbonyl]oxy}methyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

7-ethoxy-7-oxoheptyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

({[1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazin-4-yl]carbonyl}oxy)methyl L-leucinate;

benzyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

3-amino-3-oxopropyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

4-fluorobenzyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

4-(methoxycarbonyl)benzyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

[(2-methylbutanoyl)oxy]methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

4-(methoxycarbonyl)benzyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

7-ethoxy-7-oxoheptyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

7-ethoxy-7-oxoheptyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

4-fluorobenzyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

6-ethoxy-6-oxohexyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

6-ethoxy-6-oxohexyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

1-{[(cyclohexyloxy)carbonyl]oxy}ethyl 1-ethyl-5-(1,7-naphthyridin-5-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

benzyl 1-ethyl-6-oxo-3-pyridin-4-yl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

({[1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazin-4-yl]carbonyl}oxy)methyl morpholine-4-carboxylate;

{[(methylamino)carbonyl]oxy}methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

{[(dimethylamino)carbonyl]oxy}methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

(acetyloxy)methyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

[(dibutoxyphosphoryl)oxy]methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

(acetyloxy)methyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

[(isopropoxycarbonyl)oxy]methyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

{[(cyclohexyloxy)carbonyl]oxy}methyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

(acetyloxy)methyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

[(isopropoxycarbonyl)oxy]methyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

{[(cyclohexyloxy)carbonyl]oxy}methyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

(acetyloxy)methyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

[(isopropoxycarbonyl)oxy]methyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

{[(cyclohexyloxy)carbonyl]oxy}methyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-(2-thienyl)-1,6-dihydropyridazine-4-carboxylate;

{[(cyclohexyloxy)carbonyl]oxy}methyl 1-ethyl-6-oxo-5-(pyridin-3-ylamino)-3-(3-thienyl)-1,6-dihydropyridazine-4-carboxylate;

1-{[(cyclohexyloxy)carbonyl]oxy}ethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate—

Enantiomer 1;

1-{[(cyclohexyloxy)carbonyl]oxy}ethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate—

Enantiomer 2;

chloromethyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

(propionyloxy)methyl 1-ethyl-5-[(4-methylpyridin-3-yl)amino]-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

{[(1-ethylpropoxy)carbonyl]oxy}methyl 1-ethyl-3-(4-fluorophenyl)-6-oxo-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

{[(cyclohexyloxy)carbonyl]oxy}methyl 1-ethyl-3-(4-fluorophenyl)-6-oxo-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

chloromethyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

(propionyloxy)methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

(propionyloxy)methyl 1-ethyl-5-(isoquinolin-4-ylamino)-6-oxo-3-phenyl-1,6-dihydropyridazine-4-carboxylate;

(pentanoyloxy)methyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

2-oxo-1,3-dioxolan-4-yl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

fluoromethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate;

1-{[(cyclohexyloxy)carbonyl]oxy}ethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate—

Enantiomer 1;

or

1-{[(cyclohexyloxy)carbonyl]oxy}ethyl 1-ethyl-6-oxo-3-phenyl-5-(pyridin-3-ylamino)-1,6-dihydropyridazine-4-carboxylate—

Enantiomer 2;

or a pharmaceutically acceptable salt thereof.

31. A method for treating a subject afflicted with a pathological condition or disease susceptible to amelioration by inhibition of phosphodiesterase 4, which method comprises administering to said subject an effective amount of a compound according to claim 19.

32. A method according to claim 31, wherein the pathological condition or disease is asthma, chronic obstructive pulmonary disease, rheumatoid arthritis, atopic dermatitis, psoriasis or irritable bowel disease.

33. A combination product comprising:

(i) a compound according to claim 19; and

(ii) another compound selected from (a) steroids, (b) immunosuppressive agents, (c) T-cell receptor blockers, (d) antiinflammatory drugs, (e) β

2-adrenergic agonists and (f) antagonists of M3 muscarinic receptors

for simultaneous, separate or sequential administration to a human or animal.

34. A method for treating a subject afflicted with a pathological condition or disease susceptible to amelioration by inhibition of phosphodiesterase 4, which method comprises administering to said subject an effective amount of a combination product according to claim 33.

30-1. A pharmaceutical composition comprising a compound according to claim 19 in admixture with a pharmaceutically acceptable diluent or carrier.