2-(pyridin-2-ylamino)-pyrido [2,3-d]pyrimidin-7-ones

• US 7,208,489 B2
• Filed: 01/28/2005
• Issued: 04/24/2007
• Est. Priority Date: 01/22/2002
• Status: Expired

• Current Assignee: Warner-Lambert Company (Pfizer Inc.)
• Original Assignee: Warner-Lambert Company (Pfizer Inc.)
• Inventors: Toogood, Peter Laurence, Zhou, Hairong, Vanderwel, Scott Norman, Quin, John III, Booth, Richard John, Repine, Joseph Thomas, Barvian, Mark, Sheehan, Derek J.
• Primary Examiner(s): RAO, DEEPAK R
• Application Number:
  US11/046,126
• Publication Number:
  US 20050137214A1
• Time in Patent Office: 816 Days
• Field of Search: 544/117, 544/279, 540/575, 540/600, 514/217.06, 514/218, 514/234.02, 514/252.16, 514/264.11
• US Class Current: 514/217.06
• CPC Class Codes: A61K 31/519 ortho- or peri-condensed with heterocyclic rings
• CPC Class Codes: A61K 31/675 having nitrogen as a ring hetero atom, e.g. pyridoxal phosphate
• CPC Class Codes: A61P 13/12 of the kidneys
• CPC Class Codes: A61P 15/00 Drugs for genital or sexual disorders for disorders of sex hormones A61P5/24; Contraceptives
• CPC Class Codes: A61P 17/00 Drugs for dermatological disorders
• CPC Class Codes: A61P 17/06 Antipsoriatics
• CPC Class Codes: A61P 19/02 for joint disorders, e.g. arthritis, arthrosis
• CPC Class Codes: A61P 25/00 Drugs for disorders of the nervous system
• CPC Class Codes: A61P 25/28 for treating neurodegenerative disorders of the central nervous system, e.g. nootropic agents, cognition enhancers, drugs for treating Alzheimer's disease or other forms of dementia
• 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 3/10 for hyperglycaemia, e.g. antidiabetics
• CPC Class Codes: A61P 31/00 Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics
• CPC Class Codes: A61P 31/10 Antimycotics
• CPC Class Codes: A61P 31/12 Antivirals
• CPC Class Codes: A61P 31/18 for HIV
• CPC Class Codes: A61P 31/22 for herpes viruses
• CPC Class Codes: A61P 35/00 Antineoplastic agents
• CPC Class Codes: A61P 35/02 specific for leukemia
• CPC Class Codes: A61P 37/06 Immunosuppressants, e.g. drugs for graft rejection
• CPC Class Codes: A61P 43/00 Drugs for specific purposes, not provided for in groups A61P1/00-A61P41/00
• CPC Class Codes: A61P 9/00 : Drugs for disorders of the cardiovascular system
• CPC Class Codes: A61P 9/10 : for treating ischaemic or atherosclerotic diseases, e.g. antianginal drugs, coronary vasodilators, drugs for myocardial infarction, retinopathy, cerebrovascula insufficiency, renal arteriosclerosis
• CPC Class Codes: C07D 471/04 : Ortho-condensed systems
• CPC Class Codes: Y02A 50/30 : Against vector-borne diseases, e.g. mosquito-borne, fly-borne, tick-borne or waterborne diseases whose impact is exacerbated by climate change

Abstract

The present invention provides substituted 2-aminopyridines useful in treating cell proliferative disorders. The novel compounds of the present invention are potent inhibitors of cyclin-dependent kinases 4 (cdk4)

Claims

1. A compound of the formula I:

2. A compound of claim 1, having the following structure:

3. A compound of claim 1 or claim 2 wherein R³ is a cyclopentyl group.

4. A compound according to claim 2 wherein R¹ is methyl.

5. A compound according to claim 2 wherein R² is (CO)CH₃.

6. A compound according to claim 1 selected from the group consisting of:

6-Acetyl-8-cyclopentyl-2-[5-(3,5-dimethyl-piperazin-1-yl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-[5-(3,3-dimethyl-piperazin-1-yl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-[5-(4-methyl-piperazin-1-yl)-pyridin-2-ylamino]-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-2-[5-(3-amino-pyrrolidin-1-yl)-pyridin-2-ylamino]-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-(5-morpholin-4-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

2-{5-[Bis-(2-methoxy-ethyl)-amino]-pyridin-2-ylamino}-6-bromo-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-(5-morpholin-4-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-2-{5-[bis-(2-methoxy-ethyl)-amino]-pyridin-2-ylamino}-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

4-[6-(8-Cyclopentyl-6-iodo-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino)-pyridin-3-yl]-piperazine-1-carboxylic acid tert-butyl ester,

8-Cyclopentyl-6-iodo-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

2-(5-[Bis-(2-methoxy-ethyl)-amino]-pyridin-2-ylamino]-6-bromo-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-2-{5-[bis-(2-methoxy-ethyl)-amino]-pyridin-2-ylamino}-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-(pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-[5-(4-methyl-piperazin-1-yl)-pyridin-2-ylamino]-8H-pyrido[2,3-d]pyrimidin-7-one,

8-Cyclopentyl-6-(1-ethoxy-vinyl)-5-methyl-2-[5-(4-methyl-piperazin-1-yl)-pyridin-2-ylamino]-8H-pyrido[2,3-d]pyrimidin-7-one,

(1-{6-[8-Cyclopentyl-6-(1-ethoxy-vinyl)-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino]-pyridin-3-yl}-pyrrolidin-3-yl)-carbamic acid tert-butyl ester,

6-Acetyl-8-cyclopentyl-2-(4-hydroxy-3,4,5,6-tetrahydro-2H-[1,3′

]bipyridinyl-6′

-ylamino)-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

4-[6-(6-Bromo-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino)-pyridin-3-yl]-azepane-1-carboxylic acid tert-butyl ester,

6-Bromo-8-cyclopentyl-2-(5-[1,4]diazepan-1-yl-pyridin-2-ylamino)-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

4-{6-[8-Cyclopentyl-6-(1-ethoxy-vinyl)-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino]-pyridin-3-yl}-[1,4]diazepane-1-carboxylic acid tert-butyl ester,

6-Acetyl-8-cyclopentyl-2-(5-[1,4]diazepan-1-yl-pyridin-2-ylamino)-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-(pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimindin-7-one,

4-[6-(8-Cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino)-pyridin-3-yl]-piperazine-1-carboxylic acid tert-butyl ester,

8-Cyclopentyl-5-methyl-2-(5-piperazin-4-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

4-[6-(6-Bromo-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino)-pyridin-3-yl]-2,2-dimethyl-piperazine-1-carboxylic acid tert-butyl ester,

6-Bromo-8-cyclopentyl-2-[5-(3,3-dimethyl-piperazin-1-yl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3d]pyrimidin-7-one,

4-{6-[8-Cyclopentyl-6-(1-ethoxy-vinyl)-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino]-pyridin-3-yl}-2,2-dimethyl-piperazine-1-carboxylic acid tert-butyl ester,

4-[6-(6-Bromo-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino)-pyridin-3-yl]-2,6-dimethyl-piperazine-1-carboxylic acid tert-butyl ester,

6-Bromo-8-cyclopentyl-2-[5-(3,5-dimethyl-piperazin-1-yl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

4-{6-[8-Cyclopentyl-6-(1-ethoxy-vinyl)-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimindin-2-ylamino]-pyridin-3-yl}-2,6-dimethyl-piperazine-1-carboxylic acid tert-butyl ester,

8-Cyclopentyl-6-(1-ethoxy-vinyl)-5-methyl-2-(5-morpholin-4-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-(3,4,5,6-tetrahydro-2H-[1,3′

]bipyridinyl-6′

-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

8-Cyclopentyl-6-(1-ethoxy-vinyl)-5-methyl-2-(3,4,5,6-tetrahydro-2H-[1,3′

]bipyridinyl-6′

-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-(3,4,5,6-tetrahydro-2H-[1,3′

]bipyridinyl-6′

-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-2-[5-(2,6-dimethyl-morpholin-4-yl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

8-Cyclopentyl-2-[5-(2,6-dimethyl-morpholin-4-yl)-pyridin-2-ylamino]-6-(1-ethoxy-vinyl)-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-[5-(2,6-dimethyl-morpholin-4-yl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

8-Cyclopentyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino)-6-propionyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-(5-piperizin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

2-[5-(4-tert-Butoxycarbonyl-piperazin-1-yl)-pyridin-2-ylamino]-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidine-6-carboxylic acid ethyl ester,

6-Acetyl-8-cyclopentyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-[5-(3-ethylamino-pyrrolidin-1-yl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-(5-pyrrolidin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-2-{5-[3-(1-amino-1-methyl-ethyl)-pyrrolidin-1-yl]-pyridin-2-ylamino}-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

1-[6-(6-Acetyl-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino)-pyridin-3-yl]-pyrrolidine-2-carboxylic acid,

6-Acetyl-8-cyclopentyl-2-[5-(4-diethylamino-butylamino)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-(3,4,5,6-tetrahydro-2H-[1,3′

]bipyridinyl-6═

-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-2-(5-diethylamino-pyridin-2-ylamino)-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

2-{5-[Bis-(2-hydroxy-ethyl)-amino]-pyridin-2-ylamino}-6-bromo-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

2-[5-(2-Amino-ethylamino)-pyridin-2-ylamino]-6-bromo-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-2-(5-dimethylamino-pyridin-2-ylamino)-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

N-[6-(6-Bromo-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino)-pyridin-3-yl]-N-methyl-acetamide,

6-Bromo-8-cyclopentyl-2-[5-(2-methoxy-ethoxy)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-2-[5-(2-methoxy-ethoxymethyl)-pyridin-2-)Amino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-2-[5-(2-diethylamino-ethoxy)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-(5-pyrrolidin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-(6-methyl-5-piperazin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-(3,4,5,6-tetrahydro-2H-[1,3′

]bipyridinyl-6′

-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-(5-diethylamino-pyridin-2-ylamino)-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-2-{5-[bis-(2-hydroxy-ethyl)-amino]-pyridin-2-ylamino}-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-2-[5-(2-amino-ethylamino)-pyridin-2-ylamino]-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-(5-dimethylamino-pyridin-2-ylamino)-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

N-[6-(6-Acetyl-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino)-pyridin-3-yl]-N-methyl-acetamide,

6-Acetyl-8-cyclopentyl-2-[5-(2-methoxy-ethoxy)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-[5-(2-methoxy-ethoxymethyl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-[5-(2-diethylamino-ethoxy)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-(5-pyrrolidin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-(6-methyl-5-piperazin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-[5-(2-methoxy-ethoxy)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-[5-(2-methoxy-ethylamino)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-2-(5-azetidin-1-yl-pyridin-2-ylamino)-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimindin-7-one,

6-Acetyl-2-(5-azepan-1-yl-pyridin-2-ylamino)-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

N-[6-(6-Acetyl-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino)-pyridin-3-yl]-acetamide,

6-Acetyl-8-cyclopentyl-5-methyl-2-(5-phenylamino-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-[5-(4-fluoro-benzylamino)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

N-[6-(6-Acetyl-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidin-2-ylamino)-pyridin-3-yl]-methanesulfonamide,

6-Acetyl-8-cyclopentyl-2-(5-methanesulfonyl-pyridin-2-ylamino)-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-(5-phenyl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-[5-(piperazine-1-carbonyl)-pyridin-2-ylamino]-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-2-[5-(3,5-dimethyl-piperazine-1-carbonyl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

2-[5-(3-Amino-pyrrolidine-1-carbonyl)-pyridin-2-ylamino]-6-bromo-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-[5-(morpholine-4-carbonyl)-pyridin-2-ylamino]-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-[5-(piperazine-1-carbonyl)-pyridin-2-ylamino]-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-[5-(3,5-dimethyl-piperazine-1-carbonyl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-2-[5-(3-amino-pyrrolidine-1-carbonyl)-pyridin-2-ylamino]-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-[5-(morpholine-4-carbonyl)-pyridin-2-ylamino]-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-[5-(piperazine-1-sulfonyl)-pyridin-2-ylamino]-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-[5-(morpholine-4-sulfonyl)-pyridin-2-ylamino]-8H-pyrido[2,3-d]pyrimidin-7-one,

2-[5-(3-Amino-pyrrolidine-1-sulfonyl)-pyridin-2-ylamino]-6-bromo-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-2-[5-(3,5-dimethyl-piperazine-1-sulfonyl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-[5-(piperazine-1-sulfonyl)-pyridin-2-ylamino]-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-5-methyl-2-[5-(morpholine-4-sulfonyl)-pyridin-2-ylamino]-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-2-[5-(3-amino-pyrrolidine-1-sulfonyl)-pyridin-2-ylamino]-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-[5-(3,5-dimethyl-piperazine-1-sulfonyl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one, and

6-Acetyl-8-cyclopentyl-5-methyl-2-([1,6]naphthyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-8-cyclopentyl-2-[5-(1,1-dioxo-1|6-thiomorpholin-4-yl)-pyridin-2-ylamino]-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

8-Cyclopentyl-6-hydroxymethyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-2-(3-chloro-5-piperazin-1-yl-pyridin-2-ylamino)-8-cyclopentyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one,

4-[6-Acetyl-5-methyl-7-oxo-2-(pyridin-2-ylamino)-7H-pyrido[2,3-d]pyrimidin-8-yl]-cyclohexanecarboxylic acid,

4-[6-Acetyl-2-(5-dimethylamino-pyridin-2-ylamino)-5-methyl-7-oxo-7H-pyrido[2,3-d]pyrimidin-8-yl]-cyclohexanecarboxylic acid,

6-Bromo-8-cyclopentyl-5-methyl-2-[5-(piperazine-1-sulfonyl)-pyridin-2-ylamino]-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-5-methyl-2-(5-methyl-pyridin-2-ylamino)-8-piperidin-4-yl-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Acetyl-2-[5-(3,4-dihydroxy-pyrrolidin-1-yl)-pyridin-2-ylamino]-8-methoxymethyl-5-methyl-8H-pyrido[2,3-d]pyrimidin-7-one.

7. A compound according to claim 1 selected from the group consisting of:

6-Bromo-8-cyclopentyl-5-methyl-2-(5-piperizin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

2-[5-(4-tert-Butoxycarbonyl-piperazin-1-yl)-pyridin-2-ylamino]-8-cyclopentyl-5-methyl-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidine-6-carboxylic acid ethyl ester,

6-Acetyl-8-cyclopentyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

6-Bromo-8-cyclopentyl-5-methyl-2-(pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one,

and pharmaceutilly acceptable salts thereof.

9. A pharmaceutical composition comprising a therapeutically effective amount of a compound according to claim 1 and a pharmaceutical carrier, diluent, or excipient therefor.

8. A pharmaceutically acceptable salt of 6-Acetyl-8-cyclopentyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one.