FI67381B - FRUIT PROCEDURE FOR FRAMSTAELLNING AV ETT 6-FLUORO-1,8-NAPHTHYRIDINDERIVAT ANVAENDBART SOM ANTIBAKTERIELLT MEDEL - Google Patents

Description

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Japan-Japan (JP) 122220/79 (71) Dainippon Pharmaceutical Co., Ltd., 25, 3-chome, Doshomachi, Higashi-ku, Osaka, Japan-Japan (JP) (72) Jun-ichi Matsumoto, Ikoma- shi, Nara-ken, Yoshiyuki Takase, Amagasaki-shi, Hyogo-ken, Teruyuki Miyamoto, Sakai-shi, 0saka-fu, Japan-Japan (JP) (74) Oy Kolster Ab (54) Method for use as antibacterial agent 6-fluoro -1,8 - for the preparation of a naphthyridine derivative - For the preparation of a 6-fluoro-1,8-naphthyridine derivative having an antibacterial composition

The present invention relates to a process for the preparation of a 6-fluoro-1,8-naphthyridine derivative of formula I useful as an antibacterial agent.

F ° COOH

HN ®

\ _ / n U

° 2w5

and its salts, which process is characterized by oxidizing a 1,8-naphthyridine derivative of formula II

= c.

R.-N

Wherein R 1 is hydrogen or a protecting group, and R 2 is hydrogen or lower alkyl having 1 to 4 carbon atoms, and when R 1 is a protecting group, the reaction product obtained is hydrolyzed.

In the above formula, the protecting group R 1 is, for example, an acyl group such as ethoxycarbonyl, trichloroethoxycarbonyl, benzyloxycarbonyl, acetyl or trifluoroacetyl, an arylsulfonyl group such as p-toluenesulfonyl, and the like, which can be easily removed by hydrolysis.

The compound of the formula I is known per se from FI patent application 792 645 (patent 66 379).

The compound of formula I and its salts are useful antibacterial agents against gram-positive bacteria such as Staphylococcus aureus strains and gram-negative bacteria such as Escherichia coli-Pseudomonas aeruginosa strains.

The compound of formula I and its hydrochloride or methanesulfonate have a particularly advantageous therapeutic effect at low doses in urinary tract infections (ascending nephritis), systemic infections, etc. infections caused by various pathogenic bacteria. In addition, their toxicity is very low. Examples of the antibacterial activity, toxicity and plasma of 1-ethyl-6-fluoro-1,4-dihydro-4-dihydro-4-oxo-7- (1-piperidinyl) -1,8-naphthyridine-3-carboxylic acid (Compound 1) prepared by the process of the invention and blood levels, the following experiments are presented.

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Experiment 1 (in vitro antibacterial activity)

MIC

Kanta (ug / ing)

Staphylococcus aureus 209? JC-1 0.78

Gram-positive No. 5077-0.78 bacteria

Streptococcus faecalis P-2473 12.5 "pyogenes 65-A 12.5

Corynebacterium pyogenes C-21 1.56

Escherichia coli NIHJ JC-2 0 ^, 2 "" P-5101 0.1 "" P-140a 0.2

Salmonella typhimurium S-9 0.1 "enteritidis No. 1891 0.1

Shigella flexneri 2a 0f2 __ "" P-350 ____ 0.59

Gram-nega- Klebsiella pneumoniae No. 13 0.2 bacteria Enterobacter cloacae P-254-0 0.2

Pseudomonas aeruginosa Tsuchijima 0.39 "" 1110 12 0.78

Serratia marcescens IFO 3756 0.39

Proteus morganii Kono 0.2 "mirabilis P-2381 0.39

The figures in the table refer to the minimum inhibitory concentrations (MIC: pg / ml) measured by the method described in Chemotherapy, 22 (6), 1126 (1974).

4 67381

Experiment 2 (Therapeutic Effect on Infections) ED50

Infection Strain (mg / kg) (* 1) Staphylococcus aureus No. 5077 ^ 10

Systemic ------ injection Escherichia coli P-5301 Ifö

Pseudomonas aeruginosa No. 12 9.0

Ascending x 2 kidney- Pseudomonas aeruginosa No. 12 2r4- inflammation (x 1) Experimental conditions Experimental animal: male mouse (ddY-S)

Bacterial count: (1) Staphylococcus aureus No. 50774; g 5 x 10 live cells / mouse.

(2) Escherichia coli P-5101, 9 x 10 6 live cells / mouse (3) Pseudomonas aeroginosa No. 12, 3 x 10 x live cells / mouse.

By infecting:

Staphylococcus aureus No. 50774: intravenous injection of Escherichia coli P-5101 and Pseudomonas aeruginosa No. 12: intraperitoneal injection.

Medication:

Orally, Compound 1 is administered immediately after infection and 6 hours after infection.

Evaluation of results: ED, -Q values were calculated from the proportion of survivors 14 days after infection in Staphylococcus aureus No. 50774 infection, 7 days after Escherichia coli P-5101 infection and on the same day in Pseudomonas aeruginosa No. 12 infection (Behrens-Kaer method) .

5 67381 x 2 Test method

Female mice (22-30 g) were opened under pentobarbital anesthesia (manufactured by Dainippon Pharmaceutical Co., Ltd). The bladder was infected by injecting 0.1 ml of a cell suspension of Pseudomonas aeruginosa No. 12 in trypto-soy broth (manufactured by Eiken Kagaku Co., Ltd.) at a dilution of 1.5: 10,000. Mice were not allowed to drink for two days starting the day before infection and continuing to the day of infection. Compound 1 was administered orally at 3, 8, 24, 30, 48 and 54 hours after infection. On the fifth day of drug administration, mice were sacrificed and their kidneys were removed, dissected, and the sectioned surface was pressed onto King A agar, which was then incubated at 37 ° C overnight. If no bacteria were found in the kidneys, the medication was considered effective. ED 2 Q values (mg / kg) were calculated by Probit analysis.

Experiment 3 (toxicity)

Acute toxicity

Compound 1 was administered orally to male mice (ddY-S). The LDj-Q value was calculated from the number of surviving animals after 7 days by the Baehrens-Kaerber method. The LD50 (mg / kg) was greater than 4,000.

Subacute toxicity

Compound 1 was administered orally suspended in 0.2% carboxymethylcellulose solution to 6 female mice (JCL-ICR strain) weighing an average of 20 g at a dose of 2 g / kg once daily for 14 days. During the experiment, the weight of each mouse was measured. At day 15, the mice were examined hematologically and sacrificed, and their organs were weighed and examined histopathologically.

As a result, no abnormalities in weight development, organ weight, hematology studies, and histopathology were observed in Compound 1-treated experimental animals.

Experiment 4 (plasma and urine concentrations) Sample Plasma Urine

Time (hours) 0.5 1 2 3 6 8 10 0-24

Concentration 0.6 2.4 5.5 5.9 4.2 3.7 2.4 606

(μg / ml) / 40.7% J

6 67381

The number in parentheses indicates the amount (%) of compound 1 recovered from the urine.

Experimental Procedure

Two male Beagle dogs (12 kg each) were orally administered a capsule containing milk at a dose of 25 mg / kg with milk (20 ml). After administration, blood was drawn from the vessel at regular intervals from the vessel, and the blood of the cumin dog was centrifuged separately, and the plasma was separated. Total urine from dogs was collected for 24 hours after compound administration. Concentrations of Compound 1 in plasma and pooled urine were determined by the thin-layer cup plate method using Escherichia coli Kp strain as an indicator.

According to the invention, a compound of formula I can be prepared in excellent yield by oxidizing a compound of formula II dissolved or suspended in a solvent and then optionally hydrolysing the reaction product to remove the protecting group. Such oxidation can be performed using any of the oxidation methods or oxidants commonly used to oxidize aldehydes (R-CHO where R is an organic group) or ketones (R-COCH 2) to organic carboxylic acids (R-COOH). The starting material (II) can be oxidized, for example, by treatment with a hypohalite such as potassium hypochlorite or sodium hypojodite; a manganese or chromium compound such as potassium permanganate, sodium dichromate or chromium trioxide; nitric acid; with air (oxygen) in the presence of potassium tert-butoxide; iodopyridine and alkali; or carbon tetrachloride in the presence of an alkali in an aqueous solvent such as tert-butanol-water. Oxidation of a compound of formula II with bromine or iodine in alkaline solution corresponds to oxidation with the above-mentioned hypohalites. The reaction temperature and solvent must be selected according to the oxidation method. The reaction temperature is usually -5 ° to 100 ° C, preferably 5 ° to 80 ° C. The solvent used can be any that does not participate in the above-mentioned oxidation reaction and remains unchanged under the oxidation conditions. Suitable solvents are, for example, dioxane, acetone, pyridine, chloroform, tert-butanol, ethanol, hexamethylphosphoric triamide (i.e.

7 67381 tris (dimethylamino) phosphine oxide), acetic acid, water and mixtures of water and the above-mentioned organic solvents.

When a compound of formula II having a protecting group is used as a starting material, deprotection can take place simultaneously with oxidation, depending on the reaction conditions.

If the protecting group is still in place after oxidation, it can be removed by hydrolysis, if desired, to give a compound of formula I.

The hydrolysis reaction is carried out by contacting the obtained compound with water. Generally, the reaction is carried out to accelerate it in the presence of a catalyst such as an acid or a base. Examples of acids are inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid or phosphoric acid, and organic acids such as acetic acid, trifluoroacetic acid, formic acid or toluenesulfonic acid.

Examples of bases are alkali metal hydroxides such as sodium hydroxide, alkaline earth hydroxides such as barium hydroxide, alkali metal carbonates such as sodium carbonate or potassium carbonate, and sodium acetate.

The reaction can also be carried out directly by heating the obtained compound with one of the above-mentioned acids and then adding water. The solvent is usually water, but depending on the properties of the compound obtained, for example, ethanol, dioxane, ethylene glycol dimethyl ether, benzene or acetic acid can be used with water. The reaction temperature is usually 0 ° to 150 ° C, preferably 30 ° to 100 ° C.

The compound prepared by the process of the invention can be isolated and purified by conventional methods. Depending on the starting materials and reaction conditions, the compound of the formula I can be obtained either as the free compound or as a salt thereof. The compound of formula I may be converted into a pharmaceutically acceptable salt by treatment with an acid or base. As the acid, many different organic and inorganic acids can be used, such as hydrochloric acid, acetic acid, lactic acid, succinic acid, lactobionic acid and methanesulfonic acid.

8 67381

The 1,8-naphthyridine derivative prepared according to the invention has, as shown by the above experiments, excellent antibacterial properties and low toxicity. Thus, this compound can be used as a medicament in the treatment or prevention of bacterial infections in warm-blooded animals, including humans.

The drug dose of a compound of formula I or a salt thereof should be adjusted according to the age, body weight and disease state of the recipient, as well as the mode of administration, the frequency of administration, and the like. Usually the dose for an adult human is 0.1 to 7 g / day, preferably 0.2 to 5 g / day.

The compound of the invention may be used as a medicament in the form of pharmaceutical preparations which, in addition to the active ingredient, contain an organic or inorganic pharmaceutically acceptable solid or liquid excipient suitable for oral or topical administration.

Pharmaceutically acceptable excipients are those that do not react with a compound of the invention. Examples are water, gelatin, lactose, starch, cellulose (preferably microcrystalline cellulose), carboxymethylcellulose, methylcellulose, sorbitol, magnesium stearate, talc, vegetable oils, benzyl alcohol, gums, propylene glycol, polyalkylene glycol, methylalkylene glycols, methylalkyl glycols, methylalkyl glycols. The pharmaceutical preparations may be powders, granules, tablets, ointments, suppositories, ointments, capsules, etc. They may be sterilized and / or may contain additional preservatives, stabilizers or surfactants. They may also contain other therapeutically active valuable therapeutic agents.

The starting materials of the formula II are novel compounds which are prepared, for example, as described in the following reference example. The following reference example and examples illustrate the invention in detail.

Starting Example 2 2,6-Dichloropyridine (450 g) was added to a mixture of fuming nitric acid (1350 ml) and concentrated sulfuric acid (2250 ml). The mixture was heated on a steam bath at 100 ° C with stirring for 4 hours. The reaction mixture 67381 was cooled and then poured into ice water (50 mL) with stirring.

The resulting precipitate was collected and washed with water. The product obtained from the two batches of the method described above was dissolved in 5000 ml of chloroform. The chloroform solution was neutralized with saturated NaHCO 3 solution and the chloroform layer was separated. The chloroform was distilled off to give 880 g of 2,6-dichloro-3-nitropyridine, which was used without purification in the next reaction step.

A mixture of anhydrous piperazine (785 g), chloroform (4000 ml), ethanol (1000 ml) and triethylamine (635 ml) was cooled to -20 ° C. A cooled (-20 ° to -13 ° C) chloroform solution of 2,6-dichloro-3-nitropyridine (880 g) was added to the cold mixture with stirring. To this solution were added acetic anhydride (1293 mL) and chloroform (1300 mL) over 30 minutes. Stirring was continued for 20 minutes. The reaction mixture was added to about 1000 ml of water. The chloroform layer was separated and the solvent was evaporated. The residue was crystallized from water-ethanol to give 1.2 kg of 2- (4-acetyl-1-piperazinyl) -6-chloro-3-nitropyridine, m.p. 137-138 ° C (recrystallization from ethyl acetate).

2- (4-Acetyl-1-piperazinyl) -6-chloro-3-nitropyridine (1.0 kg; 25% ammonia (3000 mL) and ethanol (3000 mL) was placed in an autoclave and heated to 90-91 °. With stirring at 4 ° C. The precipitate formed was collected, washed with water and dried to give 610 g of 2- (4-acetyl-1-piperazinyl) -6-amino-3-nitropyridine, mp 202-203 ° C ( recrystallization from ethanol-chloroform).

A mixture of 2- (4-acetyl-1-piperazinyl-6-amino-3-nitropyridine (1744 g), acetic acid (6000 ml) and acetic anhydride (1100 ml) was heated under reflux for 1.5 hours and evaporated to dryness under reduced pressure. acetone (ca. 4000 mL), the crystals were collected to give 1869 g of b-acetylamino-2- (4-acetyl-1-piperazinyl) -3-nitropyridine, mp 189-193 ° C, and 221-223 ° C. C (crystallization from acetonitrile).

To a stirred suspension of 6-acetylamino-2- (4-acetyl-1-piperazinyl-3-nitropyridine (1.0 kg) in a mixture of acetic acid (4000 ml) and ethanol (8000 ml) was added at 50-55 ° C over 1 hour. 1464 g of zinc dust in portions, the mixture was filtered and the filtrate was evaporated to dryness under reduced pressure, and the residue was dissolved in a mixture of 42% aqueous tetrafluoroboric acid (2400 ml) and ethanol (2400 ml), cooled to below -5 ° C and added with stirring. Within 25 minutes, a solution of sodium nitrite (269.4 g) in water (400 ml) was stirred for a further 20 minutes, the precipitate formed was collected and washed with ethanol (1000 ml) to give 1158 g of 6-acetylamino-2- (4-acetyl · - 1-piperazinyl) pyridine-3-diazonium tetrafluoroborate, mp 121-124 ° C.

A suspension of diazonium tetrafluoroborate (1322 g) in cyclohexane (13 liters) was heated to reflux with stirring for 5 hours. The mixture was cooled, the reddish brown precipitate was collected and suspended in a mixture of water (4000 ml) and chloroform (3000 ml) with vigorous stirring. The organic phase was separated. The aqueous phase was shaken once more with chloroform (1000 ml). The combined chloroform extracts were washed with dilute aqueous ammonia, and the solvent was distilled off. The residue was crystallized from ether (4000 ml) to give 467 g of 6-acetylamino-2- (4-acetyl-1-piperazinyl) -3-fluoropyridine, m.p. 178-179.5 ° C (crystallization from ethyl acetate).

A suspension of 6-acetylamino-2- (4-acetyl-1-piperazinyl) -3-fluoropyridine (255 g) in a 10% mixture of hydrochloric acid (332 ml) and methanol (1700 ml) was heated under reflux for 2 hours. The mixture was cooled and then made less acidic with sodium bicarbonate. The methanol was distilled off, the residue was neutralized with aqueous sodium bicarbonate solution and extracted with chloroform. The chloroform extract was washed and dried. The solvent was evaporated and the residue was crystallized from ethyl acetate to give 194 g of 6-amino-2- (4-acetyl-1-piperazinyl) -3-fluoropyridine, m.p. 116-118 ° C (crystallization from ethyl acetate).

A mixture of 6- (4-acetyl-1-piperazinyl) -2-amino-5-fluoropyridine (23.8 g) and ethyl ethoxymethylene acetoacetate (18.6 g) was heated and stirred at 100-110 ° C for 1 hour. To the solution was added 100 ml of ethanol. The precipitate formed on cooling the solution was filtered to give 34.4 g of ethyl N- (6- (4-acetyl-1-piperazinyl) -5-fluoro-2-pyridyl) aminomethylene / acetoacetate, m.p. 162-163 ° C (crystallization from ethanol).

11 67381

A mixture of aminomethyleneacetoacetate (10 g) and Dowtherm (100 ml} was slowly refluxed with stirring for 1 hour, cooled to about 60 ° C and treated with 200 ml of n-hexane and the precipitate formed was filtered to give 6.47 g of 3 -acetyl-7- (4-acetyl-1-piperazinyl) -6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine, mp over 300 ° C.

A mixture of 1,4-dihydro-4-oxo-1,8-naphthyridine (6.0 g), dimethylformamide (50 ml) and potassium carbonate (6.0 g) was heated at 60 ° C with stirring for 15 minutes. 4.3 ml of ethyl iodide were added to the solution, and the solution was refluxed for 1 hour, then evaporated to dryness under reduced pressure. The residue was dissolved in water, and the solution was extracted with chloroform. The extract was washed with water and dried. The chloroform was distilled off, and the resulting crystalline residue was recrystallized from ethanol to give 4.58 g of 3-acetyl-7- (4-acetyl-1-piperazinyl) -1-ethyl-6-fluoro-1,4 -dihydro-4-oxo-1,8-naphthyridine, m.p. 225-226 ° C.

Example 1 A suspension of 3-acetyl-7- (4-acetyl-1-piperazinyl) -1-ethyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine (1.44 g) in water ( 20 ml) and 10% sodium hypochlorite solution (20 ml) were added with stirring at room temperature 4 ml of 2N sodium hydroxide. Stirring was continued for 6 hours, then the solution was neutralized with acetic acid. The precipitate was collected and recrystallized from chloroform-ethanol to give 1.28 g of 7- (4-acetyl-1-piperazinyl) -1-ethyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyrene. -dine-3-carboxylic acid, m.p. above 300 ° C.

To 1.0 g of the compound obtained above was added 10 ml of 5% sodium hydroxide solution, and the solution was heated on a steam bath for 30 minutes. The solution was neutralized with acetic acid while cooling with ice. The precipitate was collected and crystallized from ethanol-chloroform to give 0.7 g of 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8-naphthyridine-3- carboxylic acid (Compound 1), m.p. 220-224 ° C.

The obtained compound 1 (0.2 g) was dissolved with heating in 5% hydrochloric acid. The solution was evaporated to dryness under reduced pressure.

6 7381

The crystalline residue was filtered and recrystallized from water to give 0.21 g of compound 1 hydrochloride (HCl salt), m.p. above 300 ° C.

Compound 1 (0.2 g) was dissolved with heating in a 7% aqueous solution of methanesulfonic acid. Addition of ethanol gave a precipitate which was filtered and recrystallized from water-methanol to give 0.22 g of the methanesulfonate of compound 1 (methanesulfonic acid salt), m.p. above 300 ° C (decomposes).

Compound 1 (0.2 g) was dissolved in ethanol with heating. Acetic acid (0.2 ml) was added to the solution, and the mixture was cooled to form a precipitate. The precipitate was filtered and crystallized from ethanol to give 0.18 g of compound 1 acetate (acetic acid salt), m.p. 228-229 ° C.

Example 2 3-Acetyl-7- (4-acetyl-1-piperazinyl) -1-ethyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine (1.26 g) (described starting material A mixture of iodine (1.0 g) and pyridine (5 ml) was heated with stirring at 90-100 ° C for 1 hour. Excess pyridine was distilled off under reduced pressure. The residue was crystallized from water, and the crystals were filtered to give 1.4 g of 7- (4-acetyl-1-piperazinyl) -1-ethyl-6-fluoro-1,4-dihydro-4-oxo-1,8-nagtyridine-3 -carbonylmethylpyridinium iodide, m.p. 238-239 ° C (decomposes). The resulting iodide (1.0 g) was added to a mixture of 1N sodium hydroxide (10 ml) and ethanol (40 ml). The mixture was heated under reflux for 1 hour, then neutralized with acetic acid. The ethanol was evaporated under reduced pressure and the aqueous residue was cooled. The precipitate formed was filtered off. to give 0.4 g of 7- (4-acetyl-1-piperazinyl) -1-ethyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid, m.p. above 300 ° C.

The obtained compound was hydrolyzed by the same method as in Example 1 to give 0.26 g of compound 1.

Example 3 7- (4-Acetyl-1-piperazinyl) -1-ethyl-6-fluoro-3-formyl-1,4-dihydro-4-oxo-1,8-naphthyridine (3.46 g) was treated as described in Example 1. to give 3.1 g of 7- (4-acetyl-1-piperazinyl) -1-ethyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-67381 3-carboxylic acid.

The obtained compound was hydrolyzed by the same method as in Example 1 to give 2.0 g of compound 1.

Example 4 7- (4-Acetyl-1-piperazinyl) -1-ethyl-6-fluoro-3-formyl-1,4-dihydro-4-oxo-1,8-naphthyridine (3.46 g) and a suspension of silver oxide (prepared from 3.5 g of silver nitrate and 1.0 g of sodium hydroxide) in a mixture of water (1 ml) and ethanol (30 ml) was shaken vigorously at 10-20 ° C for 15 minutes. An aqueous solution (5 ml) containing 1.5 g of sodium hydroxide was added dropwise to the mixture. The resulting mixture was stirred at room temperature for 2 hours. Water (100 mL) was added and the mixture was filtered to remove separated silver. The filtrate was acidified and the precipitate was collected to give 3.3 g of 7- (4-acetyl-1-piperazinyl) -1-ethyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3 -carboxylic acid, m.p. above 300 ° C.

The obtained compound was hydrolyzed by the method described in Example 1 to give 2.2 g of compound 1.

Claims (1)

A process for the preparation of a 6-fluoro-1,8-naphthyridine derivative of the formula I 0 F \ J1 - COOH j - \ XjCj (i) X- / 2H5 and its pharmaceutically acceptable non-toxic salts useful as an antibacterial agent, characterized in that to oxidize a 1,8-naphthyridine derivative of the formula FyNAyc'i2 / - (JJ IJ (II) ^ - / SH5 wherein R1 is hydrogen or a protecting group, and R6 is very or lower having 1 to 4 carbon atoms, alkyl and When R1 is a protecting group, the reaction product obtained is hydrolyzed, and, if desired, the compound obtained is converted into a pharmaceutically acceptable, non-toxic salt.