Backσ_round of the Invention

The present invention relates to 2-aπ.ino-5-hydroxy- 4-pyrimidones , pharmaceutical compositions comprising such compounds and the use of such compounds in treating inflammation or other leukotriene mediated diseases, including pulmonary, asthmatic, allergic, and gastrointestinal diseases.

European Patent Application Publication No. 0 180 298 refers tc other 2-amino-5-hydroxy-4- pyri idoneε that are stated to be useful as histamine H„-antagonists .

Summary of the Invention

The present invention relates to a compound of the formula

or a pharmaceutically acceptable salt thereof, wherein R 1 is hydrogen; R2 is (C..-C, ₅ ) alkyl ,

(C--C- _r ) alkenvl , phenyl, substituted phenyl (C_-C ₂₀ )phenylalkyl, or substituted (C ₇ -C ₂₀ )phenylalkyl wherein the substituents on the substituted phenyl and substituted phenylalkyl, are independently one or two of fluoro, chloro, (C.-C,) alkyl, (C^C^ alkoxy, and trifluoromethyl; or R and R together with the nitrogen atom to which they are attached form a pyrrolidinyl, substituted pyrrolidinyl, piperidyl or substituted piperidyl group, wherein the substituents or. said substituted pyrrolidinyl and piperidyl groups

are independently ^* - one cf (C1, -C6 _c ) alkyl , p-henv-l , and

(C-C _q )phenylalkyl; and R is (C,-C ₈ ) alkyl , phenyl, substituted phenyl, (C_.-C _q ) phenylalky , cr substituted (C ₇ -Cg) henylalkyl, wherein the substituents on the substituted phenyl and substituted phenylalkyl are independently one or two of fluoro, chloro, (C.-C,) alkyl, (C-^-C.^) alkoxy, and trifluoromethyl.

The present invention also relates to a pharmaceutical composition useful in the treatment of leukotriene.mediated diseases, including inflammation, comprising an amount of a compound of the formula I effective to treat a leukotriene mediated disease and a pharmaceutically acceptable carrier.

The present invention also relates to a method of treating a leukotriene mediated disease (for example, inflammation) comprising administering to a patient in need of such treatment a compound of formula I in an amount effective to treat such disease.

Unless otherwise indicated, the alkyl groups of the compounds referred to herein (e.g. when R 2 of the compound of the formula I is (C_.-C, ₅ ) alkyl) , portions of such alkyl groups and the alkyl portions of other groups (e.g., alkenyl or phenylalkyl) referred to herein may be linear, branched or cyclic. Examples of cyclic alkyl groups include cyclopentyl and cyclohexyl.

A preferred embodiment of the invention relates to compounds of the formula I wherein R 1 is hydrogen; R2 is linear or branched (C^-C^.-) alkyl or (C ₇ -C ₂ _)phenyl¬ alkyl wherein the alkyl moiety is linear or branched;

3 and R is hydrogen or methyl. In a more preferred

1 2 3 embodiment, R is hydrogen, R is methylheptyl and R is hydrogen. Another preferred embodiment relates to compounds of the formula I wherein R 1 is heptyl, R2 is

3 hvdroσen and R is methvl.

Specific preferred compounds cf the present invention include the following: Z-heptylamino-5- rcxy- -met yl-4-p rimi ene ; 2- (6-methylheptyl-2-amino) -5-hydroxy-4-pyrimidcr_e; 2- [ (l-methyl-3-phenyl) -propyl] amino-5-hydroxy-4- pyrimidone; and 2-benzylamino-5-hydroxy-4-pyrimidone.

Other compounds of the present invention include 5-hydroxy-6-methyl-2-phenylhexylamino-4-pyrimidone and 5-hydroxy-6-methyl-2-phenylpropylamino-4-pyrimidone. Detailed Description of the Invention

Compounds cf the formula I may be prepared aε shown below in Scheme 1, which is discussed in detail below.

Scheme 1

In order to prepare compounds of the formula I wherein R is hydrogen, a compound of the formula II, wherein

1 and R2 are as defined above, s reacted with a

compound cf the fcrmula. Ill (prepared as described by

J. LaMattina, Tetrahedron Letters, 2053 (1983)) in a polar prcti solvent, under an inert atmosphere, in the presence cf an inorganic base (e.g., sodium hydroxide, potassium hydroxide or sodium hydride) or a strong organic base (e.g., sodium ethoxide or potassium tert-butoxide) , at a temperature of about 0 to about

100°C. The reaction mixture is preferably maintained at a temperature cf about 25°C for about 30 minutes to about 24 hours, more preferably for about 1 hour.

Preferred solvents are C, to C. alcohols. The resulting compound of the formula IV is reacted with an acid catalyst (e.g., hydrochloric acid) in a polar protic solvent at a temperature cf about 0 to 100°C

(preferably, about 60°C) for about 4 to about 48 hours to provide a compound of the formula I. Preferably, the acid catalyzed reaction is carried out in neat formic acid.

3 Compounds of the formula I wherein R is methyl are prepared by condensing an activated ester

(preferably an acid chloride) with 5-acetoxy-2-amino-

6-methyl-4-pyrimidone in an aprotic solvent (preferably methylene chloride or pyridine) at about -20 to about

100°C (preferably about 0°C) for about 0.5 to about 24 hours (preferably about 18 hours) with a base catalyst

(preferably, dimethylaminopyridine) . The isolated compounds are reduced with a hydride reducing agent

(e.g., diborane) in an anhydrous solvent (preferably tetrahydrofuran) for about 1 to about 24 hours

(preferably about 18 hours) at about 0 to about 50°C

(preferably about 25°C) .

Acid addition salts of the compounds of formula I are prepared in a conventional manner by treating a solution or suspension of the free base of a compound

of the formula I with about one cb.emicel equivalent of a pharmaceutically acceptable acid. Conventional concentration and recrysi allizaticr. technique? are employed in isolating the salts. Illustrative of suitable acids are acetic, lactic, succinic, maleic, tartaric, citric, gluconic, ascorbic, benzoic, cinnamic, fu aric , sulf ric, phosphoric, hydrochloric, hydrobromic, hydroiodic, εulfa ic, sulfonic such as methanesulfonic, benzenesulfonic, and related acids. Preferably, the acid is phosphoric acid.

Base addition salts of compounds of the formula I may be prepared in a conventional manner by reacting a compound of the formula I with about one chemical equivalent of inorganic base such as an alkali metal hydroxide or an alkaline earth metal hydroxide.

The activity of the compounds of formula I and their salts in the treatment of pulmonary, asthmatic, allergic and inflammatory diseases may be determined by a standard test measuring an agent's ability to inhibit cyclooxygenase and 5-lipoxygenase enzyme activity of rat basophil leukemia 5-.(RBL-l) cells. According to this test as described by Jak-εchick et al., Prostaglandins, 3^,733-747 (1978) , a onolayer of RBL-1 cells is grown for 1 or 2 days in spinner culture in Eagle's minimum essential medium, 15% heat-inactivated fetal calf serum and an antibiotic/antimycotic mixture. The cells are washed after centrifugatxon and incubated in a buffer. A volume of 0.5 ml of cell suspension is preincubated at 30°C for ten minutes with a 1 microliter dimethylsulfoxide (DMSO) solution of the agent to be tested. The incubation is initiated by

simultaneous addition cf 5 icroliters of (1 ^" * ^* C)~ arachidonic acid in ethanol and 2 microliters calcium icncphcre (A^ISS") in DKSC for final ccr.cer.traticr.s cf 5 and 7.6 micrσmoiar, respectively. Five minutes later, the incubation is terminated by the addition of 0.27 ml acetonitrile/acetic acid (100:3) . High pressure liquid chromatography is performed using acetonitrile/water/acetic acid solvent. Radiolabeled prostaglandin D ₂ (PGD ₂ ) , leukotriene B.(LTB.) , 5-hydroxy- eicosatetraenoic acid (5-HETE) , and unreacted arachidonic acid are determined. The inhibitory effect on the cyclooxygenase pathway is assessed from the reduction of PGD_ levels and the inhibitory effect on the 5-lipoxygenase pathway is assessed from the decrease in the amount of LTB. and 5-HETE.

The compounds of the formula I and their pharmaceutically acceptable salts are effective inhibitors of mammalian leukotriene biosynthesis in mammals and are thus useful in the treatment of various leukotriene mediated conditions. In particular, the compounds have utility, both as the sole active agent and also in combination with other active agents, for the treatment of various pulmonary, gastrointestinal, inflammatory, dermatological and cardiovascular conditions such as inflammation, arthritis, allergy, psoriasis, asthma, bronchitis, pulmonary hypertension and hypoxia, peptic ulcers, inflammatory bowel disease or cardiovascular spasm, such as acute myocardial infarctions, and the like in mammals, especially in humans.

For treatment of the various conditions described above, the compounds of formula I and their pharm¬ aceutically acceptable salts may be administered to a subject in need of treatment by a variety of con¬ ventional routes of administration, including oral, by injection, topical, and in an aerosol carrier composit¬ ion for administration by inhalation..

The exact dosage of a compound of the present invention will depend upon such factors as the age, weight and condition of the patient and the severity of disease. In general, however, a therapeutically- effective dose of a compound of formula I or a pharmaceutically acceptable salt thereof will range from 0.01 to 100 g/kg body weight of the subject to be treated per day, preferably 0.1 to 50 mg/kg per day.

Although the compounds of formula I and their salts can be administered alone, they will generally be administered in admixture with a pharmaceutical carrier selected with regard to the intended route of administration and standard pharmaceutical practice. For example, oral administration may be in the form of tablets containing such excipients as starch or lactose, or in the form of elixirs or suspensions containing flavoring or coloring agents. In the case of animals, they are advantageously contained in an animal feed or drinking water. For parenteral injection, they may be used in the form of a sterile aqueous solution which may contain other solutes, for example enough salt or glucose to make the solution isotonic. Other active compounds, including NSAIDS (non-steroidal antiinflammatory drugs) may be administered along with the compounds of the present invention.

The following non-limiting Examples are illustrative of the compounds erf the present invention. All meltinc points referred to in the Examples are uncorrected.

Example 1

2-Heptylamino-5-hydroxy-6-methyl-4-pyrimidone

A. 5-Acetoxy-2-amino-6-methyl-4-pyrimidone 2-Amino-5-hydroxy-6-methyl-4-pyrimidone (0.88 g, prepared as described in Hull, J. Chem. Soc. , 2033 (1956)) , was treated with pyridine (5 ml) and acetic anhydride ( ^" 0.5 ml) at 0°C. The reaction mixture was stirred at 25°C for 18 hours. Filtration provided a white solid (0.64 g) . Recrystallization (absolute ethanol) afforded a white crystalline solid (m.p.: 273-276°C) .

B. 2-Heptylamino-5-hydroxy-6-methyl-4-pyrimidone

A sample prepared as above (1.83 g, 10 mol) in pyridine (25 ml) was cooled 0°C under ^" ₂ and treated with 4-dimethylaminopyridine (1.6 g) followed by the dropwise addition of heptanoyl chloride (1.9 g, 10 mmol) in methylene chloride (10 ml) . Aqueous extractive work up gave a crude product which was used directly. This product (0.5 g, 1.7 mmol) was dissolved in dry tetrahydrofuran (THF) (10 ml) and treated with borane-THF (1M, 8 ml) . The reaction mixture was stirred overnight and was then quenched with methanol (10 ml) and concentrated on a rotary evaporator. The residue was refluxed in 20 ml of 6N HC1 for 2 hours. The cooled reaction mixture was filtered, providing a white crystalline product (m.p.: 233-235°C) .

Example 2 2- (6-Methylheptyl-2-amino) -5-hydroxy-4-pyrimidone

A. 2-N-Guanidino-6-methylheptane Acetate

3 , 5-Dimethylpyrazole-l-carboxamidine (10 g, 0.07 mol) , 2-amino-6-methylheptane (9.33 g, 0.07 mol) and acetic acid (4.5 ml) were combined and heated under reflux for 96 hours. The reaction mixture was cooled and filtered, yielding a white solid (12.6 g, 82%) m.p. 148-152°C.

B. 2- (6-Methylheptyl-2-amino) -5,5-diethoxy-6H-4- pyrimidone

The above N-alkyl guanidine (5.75 g, 25 mmol) was treated with freshly prepared sodium ethoxide (25 mmol) at 25°C for 1 hour under N ₂ . The reaction was filtered and the filtrate was added to a solution (50 ml ethanol) of 4-nitrophenyl 3-bromo-2,2-diethoxy- propionate (3.0 g, 8.3 mmol) . The reaction mixture was heated under reflux for 24 hours and was then cooled and concentrated. The residue was dissolved in ethyl acetate (100 ml) and extracted with 20% sodium car¬ bonate (2x50 ml) . The organic layer was dried (sodium sulfate) and concentrated, yielding 1.91 g (74%) of crude product. Chromatography (silca gel, 10:1, chloroform:methanol as eluent) and recryεtallization (acetonitrile) afforded an analytically pure sample, m.p. 170-172°C. Anal. Calcd. for C ₁₆ H _{33 3} 0 ₄ : C, 60.81; H, 9.99; N, 13.41. Found: C , 60.44; H, 9.98; N, 13.21.

C. 2- (6-Methylheptyl-2-amino) -5-hydroxy-4-pyrimidone The above compound (1.0 g, 3.2 mmol) was heated under reflux in formic acid (50 ml) for 24 hours. The reaction mixture was then cooled and concentrated.

Chromatography on silica gel- (chlcrofcrm:methanci, 20:1} afforded a solid (0.26 g, 34%) m. . 95-10C ^c C. Trituration cf the solid with ethancl and recrystaliization (acetonitrile) afforded an analyticallv pure sample. Anal. Calcd. for C, _^ H_.N,0_- :

1 i. __J J. 5 .

C, 60.22; H, 8.84; N, 17.56. Found: C, 59.78; H, 8.95; N, 17.31.

Example 3 The following compounds were prepared using methods similar to those set forth in Examples 1 and 2:

R ³

m.p.

(CH ₂ ) ₅ CH ₃ 237-240°C

(CH ₂ ) ₆ CH ₃ 233-235°C

CH ₃ (CH)CH ₂ CH ₂ Ph 125-126°C

CH ₂ Ph 210-215°C

CH ₃ (CH) (CH ₂ ) ₃ CH(CH ₃ ) ₂ 95-100°C

Ph = phenyl

Using the method of Jakschick et al. described above, the title compounds of Example 1 and 2 and the compounds of Example 3 were tested for their ability to inhibit lipoxygenase enzyme.

All of the compounds were active at a level of 20 micromolar.