CS235546B2 - Method of 1-ethyl-6-halogen-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridine derivatives preparation - Google Patents

Description

The invention relates to a process for the production of novel naphthyridine derivatives with high antibacterial activity. According to the invention, they are produced. compounds of formula 1

where they changed

X is fluorine or chlorine; and

C 1-2 hydrogen or C 1 -C 6 alkyl and non-toxic pharmaceutically acceptable salts thereof. Salts of the naphthyridine compounds of formula I are prepared from the naphthyridine compounds of formula I and acids or esters. The acids may be various inorganic and organic acids. Examples of suitable acids are hydrochloric acid, acetic acid, lactic acid, succinic acid, lactobonic acid and methanesulfonic acid. The bases may be any inorganic or organic bases which are capable of forming salts with the carboxyl group of a compound of formula I. Examples of suitable bases are metal hydroxides such as sodium or potassium hydroxide and metal carbonates such as sodium or potassium carbonate.

Particularly preferred salts of the compounds of formula I are the hydrochlorides or methanesulfonates.

Under certain conditions, the naphthyridine salts of formula I may form hydrates. These hydrates are also encompassed by the naphthyridine compounds of formula I of the present invention.

Typical examples of the novel compounds of the invention with their structural formulas are given below:

1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8-naphthyridine-3-carboxylic acid (compound 1) of the formula

COOH. .., 1 /

NNN HN ^^ c ₂ H _5, and a nontoxic pharmaceutically acceptable salt thereof.

Ethyl 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8-nephthyridine-3-carboxylate (ethyl ester of compound 1) of the formula

N

COOC ₂ H ₆

HN

N

I c ₂ h ₅ o

: .Cfe

And its non-toxic pharmaceutically acceptable salts and salts thereof

6-chloro-1-ethyl-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8-naphthyridine-3-carboxylic acid (compound 2) of the formula

and non-toxic pharmaceutically acceptable salts thereof.

Of the naphthyridine compounds of this invention, Compound 1 and its salts are the most valuable antibacterial agent. As shown in Tables I-1 below, Compound 1 and its salts show very high entibacterial activity in both in vitro and in vivo assays for Gram-positive and Gram-negative bacteria including Pseudomonas aeruglnosa. Since their toxicity is extremely low, they are useful for the treatment not only of the urinary tract infections caused by various gram-positive and gram-negative bacteria, but also for the treatment of systemic infections caused by these bacteria. The lower alkyl ester of compound 1 has a fairly high antibacterial activity in vivo. This ester is useful not only as an antibacterial agent, but also as an intermediate for the preparation of compound 1.

US Patent No. 4,017,622 discloses piperezine derivatives of the general formula

and salts thereof which are structurally similar to the compounds of the invention. In the above formula

R 1 represents a hydrogen atom, a C 1 -C 4 alkyl group, a benzyl group or an acetyl group,

R ₂ is hydrogen, alkyl having 1 to 4 carbon atoms, benzyl group, or a vinyl group, and

R ^ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

As can be clearly seen from the above formula, the 1,8-naphthyridine derivatives described in US Patent No. 4,017,622 have no substituent at position 6 of the naphthyridine core.

Investigations by the inventors have shown, as shown in Tables I and II below, that the compounds of the invention have much better antibacterial activity on gram-negative bacteria including Pseudomonas aeruglnosa and also against grempositive bacteria than the 1,8-naphthyridine derivatives disclosed in the aforementioned US patent.

Japanese Patent Laid-open Publication No. 83 590 (77), the summary of which is described in the Central Patent Index published by Derwent Publicetion Ltd., No. 60,389Y (34), describes 6-nitro-1,8-naphthyridine derivatives of the general formula

COOR in which

-N (R 'R') is a member of the group consisting of amino, substituted aniline, alkylamino, cycloalkylamino, dlalkylaminoalkylamino, hydroxyelkylamino, dlalkylamino, alkylalylamino, alkylcycloalkylamino, dlhydroxyelkylamino, plperol, pyrrolldln, plperolldln, plololldln, plololldin, plololldin, plolldol, R 8 represents a lower alkyl group.

However, Japanese publications merely state that these compounds have antltrlchomonelic activity. It does not relate here to the antibacterial agents of the invention.

In summary, in the Proceedings of the 98th Annuel Meeting of the Fharmeeeutleel Society of Japan, p. 233 (published March 10, 1978), ee states that compounds of the formula

in which

R, a modified ethyl group or a corresponding group thereof,

Rg represents a hydrogen atom,

R ₃ and R 6 denote groups of the alectronocceptor α type

The electron-donating group has a strong activity.

In this publication, it is noted that compounds of the above formula wherein R 1a represents a chlorine or fluorine atom and R 1 represents a plperezine or substituted plperezine group have been studied for the relationship between their structures and activities and that wherein R 1 is ethyl, R 8 is hydrogen, R 6 and R 6 are chlorine or fluorine, and R 6 is a plpiperidine group, have been found to exhibit stronger entibacterial activity than nalldix ciclines.

U.S. Patent No. 4,146,719, which corresponds to Belgian Patent No. 863,429, describes the choline derivatives of the formula (referred to as Compound D)

Japanese Patent Laid-open Publication No. 65,887 (78), the summary of which is described in Der.

436 A (29) discloses a quinoline derivative of the formula (this compound is referred to as compound C)

Investigations by the inventors have shown, as Table II-III indicates, that compounds 1 and 2 of the invention have much better antibacterial activity against gram-negative bacteria including Pseudomonas aeruginosa than quinoline derivatives such as compounds C and D.

The compounds of the formula I and their salts are prepared by reacting a compound of the formula II

O

where

X is as defined for formula I and wherein is

R 6 is a hydrogen atom or a protecting group,

R ^ is carboxy, -COOR, or R ^, wherein R ^ is cyano, carbamoyl, amidino, or formula

-C = NH1

0-R

R is an alkyl group having 1 to 6 carbon atoms, with an ethylating agent, and then the reaction product is hydrolyzed when R ^ is R ^ or the protecting group is removed from the reaction product when R ^ is a protecting group and optionally the reaction product is converted to its non-toxic, pharmaceutically acceptable salt.

Any ethylating agent may be used. Particular examples of ethylating agents include ethyl halides, such as ethyl iodide, and ethyl esters, such as, for example, diethyl sulfate, ethyl p-toluenesulfonate, or triethyl phosphate.

This ethylation reaction is generally carried out by treating a compound of formula II with a stoichiometric amount of ethylating agent in an inert solvent at an elevated temperature, for example at 25 to 150 ° C. When R1 is a protecting group, the ethylating agent can be used in excess.

Examples of solvents are ethanol, dioxane, methyl cellulose, dimethylformamide, dimethylsulfoxide and water. The reaction is accelerated by the addition of an acid acceptor, for example a base such as an alkali metal carbonate, an alkali metal hydroxide, an alkali metal alkoxide, sodium hydride, pyridine, triethylamine or benzyltrimethylammonium hydroxide.

The resulting compound at the 3-position with the substituent R ^ as R R is further hydrolyzed. The resulting compound wherein R 1 is a protecting group is subjected to a reaction to remove a protecting group, for example, solvolysis or hydrogenolysis.

This affords the desired compound. The hydrolysis reaction of the group R1 is carried out by contacting the obtained compound with water. Generally, this reaction is carried out in the presence of a catalyst, for example an acid or a base, to accelerate. Examples of acids include inorganic acids, such as hydrochloric, hydrobromic, sulfuric or phosphoric acids, and organic acids, such as acetic, trifluoroacetic, formic and toluene sulfonic acids. Examples of bases include alkali metal hydroxides such as sodium hydroxide and alkaline earth metals such as barium hydroxide, alkali metal carbonates such as sodium or potassium carbonate, and sodium acetate. The hydrolysis reaction can also be carried out directly by heating the resulting compound in the presence of the above acid and then adding water. The solvent is generally water, but an organic solvent such as ethanol, dioxane, ethylene glycol dimethyl ether, benzene or acetic acid may be used together with water depending on the properties of the compound. The reaction temperature is generally 0 to 150 ° C, preferably 30 to 100 ° C.

In the case where R 6 in the resulting compound is a protecting group, such a protecting group is removed by solvolysis including hydrolysis or, for example, hydrogenolysis.

\

The protecting group R @ 1 is a group which can be removed by solvolysis, including hydrolysis or hydrogenolysis.

Specific examples of the protecting group R @ 1 which can be removed by solvolysis include acyl groups such as formyl, acetyl, trifluoroacetyl, benzyloxycarbonyl, tert-butoxycarbonyl, p-methoxybenzyloxycarbonyl, vinyloxycarbonyl, ethoxycarbonyl, ethoxy ethoxycarbonyl, arylsulfenyl groups such as o-nitrophenylsulfenyl, tri / lower alkylsilyl groups such as trimethylsilyl, phenyl substituted methyl groups such as trityl, tetrahydropyranyl or diphenylphosphinyl.

Specific examples of the group R @ 1 which can be removed by hydrogenolysis are arylsulfonyl groups such as p-toluenesulfonyl, phenyl substituted with phenyl or benzyloxy such as benzyl, trityl or benzyloxymethyl, acyl groups such as benzyloxycarbonyl , p-methoxybenzyloxycarbonyl, beta, beta, beta-trichloroethoxycarbonyl or beta-iodoethoxycarbonyl.

When R1 is a solvolytically removable group, removal of such a protecting group is accomplished by solvolysis of the resulting compound, including hydrolysis of the resulting compound. This solvolytic reaction involving hydrolysis is accomplished by contacting the resulting compound with a solvent in the presence or absence of a catalyst, such as an acid or a base. Examples of inorganic acids include hydrochloric, hydrobromic, sulfuric, or phosphoric acids, and examples of organic acids include acetic acid, trifluorootic acid, formic acid and toluenesulfonic acid.

Examples of bases include alkali metal and alkaline earth metal hydroxides such as sodium hydroxide and barium hydroxide, alkali metal carbonates. such as sodium and potassium carbonate and sodium acetate. For example, water is used as the solvent, but depending on the properties of the resulting compound, solvents such as ethanol, dioxane, ethylene glycol dimethyl ether, benzene, acetic acid or mixtures thereof with water may be used. The reaction temperature is usually 0 to 50 ° C, preferably 30 to 100 ° C.

If the group of the symbol Ηβ is removable by reduction, the protecting group may be removed by hydrogenolysis. The hydrogenolytic reduction conditions should be chosen depending on the properties of the protecting group Ry. In general, the reaction is carried out as follows:

In the hydrogenolysis reduction, the resulting compound is treated with a stream in an inert solvent in the presence of a catalyst such as knitted fabric, palladium, Reneyl nickel or the like metal. The catalytic hydrogenolysis is carried out at room temperature. However, it can optionally be carried out at elevated temperatures of up to 60 ° C. Suitable solvents for this reaction are ethylene glycol, dioxane, dimethylformamide, ethanol and acetic acid.

When R1 is benzyl, triyl, benzyloxycarbonyl or p-toluenesulfonyl, which is a sodium-metal-cleavable group in liquid ammonia, cleavage is carried out at a temperature of -50 to -20 ° C. Hydrogenolysis can also be carried out by reacting the resulting compound with a metal such as zinc in acetic acid or an alcohol such as methanol.

For example, the starting compound of formula II can be prepared according to the following reaction scheme:

diazotace

'ν ι * γ

Η

COOEt

COOEt cyclization compound b

and ₂

Wherein G and X are as defined above, Et is ethyl and A is halogen containing an anionic group.

The cyclization reaction in the above reaction sequence (i.e. the conversion of Compound J 1 to Compound 6) is carried out as follows:

This reaction is carried out by heating the compound of formula (b) directly or in a high-boiling solvent such as diphenylether, diphenyl, o-dichloro benzene, diphenyl oxide, dibutyl phthalate or mixtures thereof. A suitable heating temperature is 140 to 260 ° C. The cyclization can also be carried out in the presence of conventional cyclizing agents such as polyphosphoric acid, lower alkyl phosphates, concentrated sulfuric acid, phosphoryl chloride or phosphorous pentoxide. When polyphosphoric acid, lower alkyl phosphates or phosphorous pentoxide is used, the reaction is usually carried out in a solvent such as benzene, dioxane or dimethylformamide. When concentrated sulfuric acid is used, the reaction is carried out in a solvent such as acetic anhydride or acetic acid. Also, the cyclizing agent may serve as a solvent, depending on its properties. When a cyclizing agent is used, the reaction is carried out at relatively low temperatures, for example at 100 to 160 ° C.

The compounds of formula (I) prepared by the process of the present invention are isolated and part of conventional methods. The compounds of formula (I) are prepared in free form or in salt form depending on the starting material used and reaction conditions. The compounds of formula (I) may be converted into pharmaceutically acceptable salts by treatment with an acid or base. The acid may be various organic or inorganic acids, for example hydrochloric acid, acetic acid, lactic acid, succinic acid, lactobionic acid, oxalic acid and methanesulfonic acid.

The new 1,8-naphthyridine derivatives of the invention, as will be explained below, have excellent antibacterial activity and low toxicity. These compounds may be used as medicaments in the treatment or prevention of bacterial infections in warm-blooded mammals including humans.

The dosage of the compound of formula (I) prepared by the method of the invention, or a salt thereof, when administered to humans should be adjusted according to the age, body weight and condition of the patient, route of administration, number of administrations and similar circumstances. For adults, the usual dose is 0.1 to 7.0 g / day, preferably 0.2 to 5.0 g / day.

The compounds prepared by the process according to the invention can be used as medicaments, for example in the form of pharmaceutical preparations which contain them in admixture with organic or inorganic pharmaceutically acceptable solid or liquid excipients which are suitable for oral or topical administration.

Pharmaceutically acceptable excipients are those which do not react with the compounds of formula I. Examples are water, gelatin, lectose, starch, cellulose (preferably microcrystalline cellulose), carboxymethylcellulose, sorbitol, magnesium stearate, talc, vegetable oils, benzyl alcohol. gums, propylene glycol, polyalkylene glycols, methylparaben (methyl-p-hydroxysalycytate) and other known medical excipients. The pharmaceutical preparations may be powders, granules, tablets, ointments, suppositories, creams, capsules and the like. They may be sterilized and / or may contain other agents such as preservatives, stabilizers or wetting agents. They may further contain other therapeutically valuable compounds according to the medical purpose.

The preparation of the novel compounds according to the invention and their salts and their pharmacological activity are illustrated in the following examples. The paragraph "Preparation 1" explains how to prepare the starting material. Examples 1 to 4 illustrate processes for preparing the compounds of formula (T) and their salts according to the invention. Paragraph "Preparation 2" describes a process for the preparation of a compound that is novel and does not fall within the scope of the invention.

Examples A to G show the pharmacological activities of the compounds of the formula I and their salts according to the invention in comparison with the compounds which are not within the scope of the invention and which are referred to as control compounds.

All prepared compounds were identified by elemental analysis, mass spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, and thin layer chromatography.

Preparation 1

c ₂ h ₅ oco-n

Reaction of the 2,6-dichloro-3-yltropyridine with N-ethoxycarbonylpiperesis affords 6-chloro-2- (4-ethoxycarbonyl-1-piperezinyl) -3-nitropyridine. The product is heated without further purification with ethanclic ammonia in a sealed tube at 120 to 125 ° C to give 6-emino-2- (4-ethoxycarbonyl-1-piperazinyl) -3-nitropyridine, m.p. 132-134 ° C. This product is treated with acetic anhydride in acetic acid to give 6-ethylemino-2- (4-ethoxycarbonyl-1-piperphenyl) -3-nitropyridine, m.p. 166-169 ° C. This compound was catalytically hydrogenated in the presence of 5% palladium on carbon in acetic acid. 3-amino-6-acetylemino-2- (4-ethoxycarbonyl-1-piperazinyl) pyridine is obtained. The obtained 3-amino derivative was dissolved in a mixture of ethanol and 42% of tetrafluoroboric acid without further purification. To this solution was added a solution of isoamylnitrile in ethanol at a temperature below 0 ° C. with stirring. After 20 ml ether was added to the solution. The resulting precipitated solid was filtered, washed with methanol-ether, then chloroform, to give 6-ethyl-amino-2- [4-ethoxycarbonyl-1-piperazinyl] -3-pyridinediazonium tetrafluoroborane, m.p. 117-117.5 °. C (decomposition).

The suspension of the diaznium salt in toluene is gradually heated up to 120 ° C (lesion temperature), which is maintained for 30 minutes with stirring. After distilling off the solvent under reduced pressure, the residue was basified with 10% sodium carbonate solution and extracted with chloroform. The chloroform extract was dried over anhydrous potassium carbonate. After distilling off the solvent, the crystalline residue was recrystallized from ethyl acetate. There was thus obtained 6-acetylamino-2- (4-ethoxycarbonyl-1-piperazinyl) -3-fluoropyridine, m.p. 132-133 ° C. 3-Fluoromethyl is further hydrolyzed with 15% hydrochloric acid / methanol (1: 2, by volume). There was thus obtained 6-amino-2- (4-ethoxycarbonyl-1-piperazinyl) -3-fluoropyridine. This compound was treated with diethylethoxymethylene malonate at 130-140 ° C to give diethyl N- (2- (4-ethoxycarbonyl-1-piperazinyl) -3-fluoro-6-pyridinyl) aminomethylene malonate, m.p. 144-145. Deň: 32 ° C. This product is then cyclized by heating at 255 ° C to give ethyl 7- (4-ethoxycarbonyl-1-piperazinyl) -6-fluoro-1,4-dihydro-4-oxo-1,8- m.p. 279-281 ° C.

He exemplified the preparation of compound Ί and its acid addition salt

Ethyl 7- (4-ethoxycarbonyl-1-piperazinyl) -6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylate (1.0 g) was suspended in dimethylformamide (10 ml) /. Potassium carbonate (0.53 g) was added to the suspension. The mixture is maintained at 60 ° C for 10 minutes with stirring. Ethyl iodide (1.2 g) was then added to the solution. The reaction mixture was stirred at 60-70 ° C for two hours. The reaction mixture was distilled to dryness under reduced pressure.

Water was added to the residue. The solution was extracted with chloroform. The chloroform extract was dried over anhydrous potassium carbonate. After distilling off the chloroform, the resulting solid was recrystallized from a mixture of dichloromethane and hexane. There was thus prepared 0.89 g of ethyl 1-ethyl-6-, fluoro-1,4-dihydro-4-oxo-7- (4-ethoxycarbonyl-1-piperazinyl) -1,8-naphthyridine-3-carboxylate. mp 171-173 ° C. A mixture of the above ethyl ester (0.8 g), 10% sodium hydroxide (6 ml) and ethanol (2 ml) was refluxed for three hours. After cooling, the pH of the solution was adjusted to 7.0-7.5 by the addition of 10% acetic acid. The precipitated solid was filtered off, washed with ethanol and recrystallized from a mixture of dimethylformamide and ethanol. 0.57 g of 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) -, 8-nephthyridine-3-carboxylic acid, having a melting point of 220 DEG to 220 DEG C., is obtained. 224 ° C.

The carboxylic acid thus prepared (0.2 g) was dissolved in 5% hydrochloric acid. The solution was evaporated to dryness under reduced pressure. The residue was recrystallized from water to give the carboxylic acid hydrochloride of melting point at 300 ° C in a yield of 0.21 g.

Alternatively, the above free carboxylic acid (0.2 g) is dissolved in a 7% methanesulfonic acid solution with heating. After cooling, the precipitated solid was recrystallized from dilute methanol. The carboxylic acid salt of methanesulfonic acid having a melting point above 300 DEG C. with decomposition (0.22 g) is obtained.

The free carboxylic acid (1.0 g) was heated in ethanol until dissolution. Acetic acid (1.0 ml) was then added. After cooling the mixture, the crystals obtained are filtered off and recrystallized from ethanol. 228 DEG-229 DEG C. (0.93 g) is obtained.

Example 2

Preparation of compound 2

6-Chloro-1-ethyl-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8-naphthyridine-3-carboxylic acid hydrochloride, m.p. > ethyl 6-chloro-7- (4-ethoxycarbonyl-1-piperazinyl) -1,4-dihydro-4-oxo-1,8-nephthyridine-3-carboxylate by the same procedure as described in Example 1.

Example 3

Preparation of the ethyl ester of compound 1

Ethyl 6-fluoro-1,4-dihydro-4-oxo-7- (4-trifluoroacetyl-1-piperazinyl) -1,8-aphthyridine-3-carboxylate is reacted with ethyl iodide and β potassium carbonate in dimethylforraamide as described in Example 1. Ethyl 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (4-trifluoroacetyl-1-piperazinyl) -1,8-naphthyridine-3- is obtained. carboxylate. This product is hydrolyzed with aqueous potassium carbonate in chloroform-methanol to give ethyl 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8-naphthyridine- M.p. 150 DEG-151 DEG.

Example 1 a d 4

Preparation of propyl and butyl ester of compound 1

Propyl 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8-naphthyridine-3-carboxylate, m.p. 133-135 ° C and butyl -1- ethyl 6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8-nephthyridine-3-carboxylate, m.p. 119-120 ° C, was prepared as described in Example 3.

Preparation 2

Described is a process for the preparation of a compound which is not within the scope of the compound of formula (I) and whose preparation has not yet been published, in order to evaluate the pharmacological effects of the novel 1,8-naphthyridine compounds prepared by the process of the invention.

Preparation of Comparative Compound of Formula

YOU ™

-xXlT

CHg-N_N N N

C ₂ H ₅

6.0 g of 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8 g was added to a solution of 37% formalin (12 ml) of formic acid (18 ml). -nthyridine-3-carboxylic acid. The mixture was heated for 4 hours at 120-125 ° C with stirring. The mixture was evaporated to dryness under reduced pressure. The pH of the residue was adjusted to 8 by adding 7% aqueous sodium bicarbonate solution. The solution was extracted with chloroform. The extract was dried and the solvent was distilled off. The crystalline residue was recrystallized from a mixture of dichloromethane and ethanol. 5.0 g of 1-ethyl-6-fluoro-1,4-dlhydroc-7- (4-methyl-1-piperazinyl) -4-oxo-1,8-nephthyridine-3-carboxylic acid are obtained, m.p. 228 to 230 ° C.

The pharmacological activities of the compounds of the formula I and their salts prepared by the process according to the invention are shown in Examples A to G in comparison with the antibacterial agents known in the art. The following compounds are tested:

Compound 1

1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) 1,8-nephthyridine-3-carboxylic acid.

HN <i

N

C ₂ H ₅

Compound 1

1-Ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8-naphthyridine-3-carboxylic acid methanesulfonate

COOH

TT

HŇ Ň 'NN .ch ₃ Sat ₃ h.

c ₂ h ₅

Compound 2

6-Chloro-1-ethyl-1,4-dlhydro-4-oxo-7- (1-piperezinyl) -1,8-naphthyridine-3-carboxylic acid hydrochloride

HN

CL

T

Ν 'N _ /

COOH. HCl

Compound A

1-ethyl-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8-naphthyridine-3-carboxylic acid (also referred to as unsubstituted 1,8-naphthyridine)

(The compound is described in U.S. Patent No. 4,017,622).

Compound 3

1-Ethyl-6-fluoro-1,4-dihydro-7- (4-methyl-1-piperazinyl) -4-oxo-1,8-naphthyridine-3-carboxylic acid. Preparation 2 /

O

c ₂ h ₅

Compound C

6-chloro-1-ethyl-1,4-dihydro-4-oxo-7- (1-piperazinyl) quinoline-3-carboxylic acid

HN N ^C '^^ JU ^COOH

Xv

C, H

2 5 ⁿ / compound is disclosed in Japanese Patent Laid Open Pat. No. 65,887 / 78 /.

Compound D

1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) quinoline-3-carboxylic acid (The compound is described in Belgian patent No. 863 429)

O

F

H

COOH

C ₂ H ₅

Compound E

1-Ethyl-1,4-dihydro-7-methyl-4-oxo-1,8-nephthyridine-3-carboxylic acid (nalipixic acid) (The compound is described in U.S. Pat. No. 3,149,104).

Compound F

8-ethyl-5,8-dihydro-5-oxo-2- (1-piperazinyl) pyrido (2,3-d) pyrimidine-6-carboxylic acid (pipemidic acid) / The compound is described in U.S. Patent No. 3,887 557 /.

Compound G

Alpha- (5-indanynyloxycarbonyl) benzylpenicillin (carindacillin) sodium salt The compound is described in U.S. Patent No. 3,557,090).

Compound H

D-alpha-Aminobenzylpenilcilin (ampicillin) (The compound is described in U.S. Patent No. 2,985,648).

Compound J

7- (D-alpha-Aminophenylacetamido) -decetoxycephalosporanic acid (Cephalexin) (described in U.S. Patent No. 3,507,861).

Example A

Table 1 shows the minimum inhibitory concentrations [mu] g / ml / in vitro.

Tabulkal,

Anti bacterial activity in vitro on 19 strains of bacteria

Bacteria Compound j_r_2

Gram-positive bacteria

Staphylococcus aureus

209P JC-1 0.78 0.78 3.13 Staphylococcus aureus No. 50,774 0.78 0.78 6.25 Streptococcus faecalis P-2473 12.5 12.5 25 Streptococcus pyogenes 65A 12.5 12.5 12.5 Corynebac teri um pyogenes C-21 1, 56 1.56 5.25

Bacteria Compound

1 1 2 Gram-negative bacteria Escherlchle coll KIHJ JC-2 Sseherlehla coll 0.2 0.2 0.78 P-5101 Escherlchle coll 0.1 0.1 0.39 P-140a 0.2 0.2 0.39 Salmonella typhtmuríum S-9 0.1 0.1 0.39 Salmonella .enterltldls No. 1891 0.1 0.1 0.39 Shlgalia flexnerl 2a Shlgella flexnerl 4a 0.2 .0,2 0,78 - P-330 0.39 0.39 1.56 Klebsiella pneumonlae No 13 0.2 0.2 1.56 Enterobacter cloacae P-2540 0.2 0.2 0.78 Pseudomonas aeruglnosa Tsuchl jlma Pseudomonas aeruglnosa 0.39 0.39 6.25 No 12 0.78 0.78 6.25 Serratia marcescens IFO 3736 0.39 0.39 1.56 Proteus morgani1 Kono Proteus mlrebllla 0.2 0.2 1.56 P-2381 0.39 0.39 3.13 Bacteria Compound « AND 3 C D E Gram-cultivating bacteria Staphylococcus aureus 209P JC-1 25 1.56 0.78 0.39 100 ALIGN! Staphylococcus aureus No. 50,774 50 1.56 1.56 0.78 50 Streptococcus faecalls P-2473 Streptococcus pyogenes > 100 12.5 6.25 3.13 > 200 65 A 50 6.25 6.25 - > 200 Corynebacterium pyogenes C-21 50 1, 56 1.56 0.78 > 200

óekterlβ Compound AND (B) C D E Gratnnegati smells good Esoheriohia coli NTHJ JC-2 6.25 0.39 0.39 0.1 12.5 Escher’chla celt P-5101 3.13 0.2 0.2 0.05 3.13 Escherlchia coli P-, 40a 6.25 0.39 0.2 0.1 Seliaonelle typliiinurtum S-9 6.25 0.2 0.2 0.05 3.13 Salmonelle enteritidis No. 1891 1.56 0.1 0.2 0.05 3.13 Shigelle flexneri 2a 6.25 0.39 0.39 0.1 6.25 Shigelle flexneri 4a 12.5 0.78 0.2 0.2 - P-330. 12.5 0.78 0.2 0.2 - Xlebsi elle pneuoioniee C. 13 2.5 0.39 0.78 0.2 12.5 Enterobacter cloacoe 6.25 0.39 0.2 0.1 6.25 P-254C 6.25 0.39 0.2 0.1 6.25 Pseudomanas ceruglnosa Tsuchijloa 25 1.56 3.13 0.39 200 Pseudomonas aeruginosa house 12 25 3.13 3.13 0.78 200 Serratie morcescens IFO 3736 12.5 1.56 0.78 0.2 6,25, Proteus merganli Horses 6.25 0.78 0.39 0.1 6.25 Proteus mirabi li s P-2381 25 1.56 0.39 0.2

Bekterie Compound F G H J Qrampositive bacteria Staphyloeoocus eureus 209P JC-1 12.5 0.39 0.05 1.56 Stnphylococcus eureus No. 50774 25 0.78 0.1 1.56 Streptococous faeoalts P-2473 200 50 1.56 200 Streptococous pyogenes 200 0.2 0,025 0.78 65 A 200 0.2 0,025 0.78 Coryne bac terum pyogenes C-21 25 3.13 1.56 1.56

π

Bacteria Compound P 0 H J Gram-negative bacteria Escherlchla ooll NIHJ JC-2 1.56 6.25 6.25 12.5 Escherlchla coli P-5101 1.56 6.25 6.25 12.5 Escherlchle cell P-140a 1.56 50 200 > 200 Selmonella typhimurium S-9 1.56 0.78 0.39 6.25 Selmonella enteritidis No. 1891 1.56 0.78 0.2 3.13 Shlgelle flexnerl 2e 3.13 12.5 3.13 12.5 Shlgelle flexnerl 4a P-330 1.56 6.25 6.25 200 Klebsielle pneumonlae No 13 6.25 > 200 100 ALIGN! 6.25 Enterobacter cloacee P-2540 1.50 3.13 > 200 > 200 Pseudomonas aeruglnosa Tsuchl jlma 12.5 6.25 > 200 > 200 Pseudomonas aeruglnosa No, 2 25 50 > 200 > 200 Serratia * marceecens IFO 3736 3.13 3.13 25 > 200 Proteus morganii Kono 3.13 0.78 100 ALIGN! > 200 Próteus mírabilis P-2381 3.13 0.78 3.13 12.5

Note: The figures in the table give the minimum inhibitory concentration (MIC) / [µg / ml]

Method: Chemotheran 22/6 /. 1126, (1974).

The results in Table I show:

1. Compounds 1, 1 * and 2, in particular compounds 1 and 1 *, prepared by the process according to the invention, show very high anti-bacterial action on both grempositive and gremnegetic bacteria, including Ponomidase eeruginose.

2. Compound A (at position 6, unsubstituted 1,8-naphthyridine) has much worse antibacterial activity against Gram-positive and Gram-negative bacteria compared to the compounds prepared by the method of the invention.

Example B (Therapeutic efficacy in vivo)

Compounds 1, 1 * and 2, the ethyl ester of compound 1 and compounds A to J are each dissolved in deionized water or suspended in a 0.2% aqueous CMC solution. The solutions are administered orally to mice infected with the test organisms under the conditions described below. The mean effective doses obtained (ED 50) are given in Table II.

Experimental conditions:

Mice: velvet / ddY · mice weighing approximately 20 g.

Infection: 1. Stephylococcus eureus No. 50,774.

Intravenous infection with a dose of 5 to 10 LD? / Approximately 5.10? Bur / mouse / bacterial bacterial suspension in saline.

2. Eseherlchla coll P-5101

Intraperltoneal infection at a dose of 5 to 10 / approximately 9:10 &lt; 5 &gt; cells / dish / bacterial suspension in tryptic soy medium with 4% mucin.

Pseudomonas aeruginosa S. 12

Intraperltoneal infection with a dose of 50 to 100 LD ^ q (approximately 5 × 10 cells) mouse / bacterial suspension in tryptosoy soy medium with 4 * mucin ·

Medication: twice, about 5 minutes after infection and 6 hours after infection

Observation: Staphylococcus aureus # 50 774 after 14 days

Eseherlchla coli P-5101 after 7 days

Pseudomonas aeruginosa 12 after 7 days

Note: The figures in Table II below indicate EI ^ ₀ (mg / kg).

ES ₅₀ values are calculated by the Behrens-Keerber / Arch method. Exp. Path. Pharm. Lie, 480, 1931].

po means oral administration calculated for the free carboxylic acid

Table II

In vivo efficacy for systemic infection in a dishwasher

* Staphylococcus aureus 50 504 Bacteria Eseherlchla eoli P-5101 Pseudomonas seruglnoso C. 12 Compound P ° administration after AFTER 1 10 1,8 9.0+ 1 ' 10 * 1,8 * 9.0 * 2 about 90 * 5,5 * 5β, 6 * ethyl ester 1 about 20 - 21; AND > 100 - > 200 (B) 4.8 1,2 10; 6 C esl 100 about 15 > 100 d 21.9 4.7 15.5 E > 800 29.2 > 200 F 215 21.2 99.5 G 10 to 40 100 ALIGN! 201.6 H 2.2 43.5 > 400 J 12.1 22.6 > 400

The results in Table II show:

Compounds 1 and 1 ', prepared by the method of the invention, show potent therapeutic efficacy for systemic infections with both Gram-positive and Gram-negative bskteria.

2. Compounds 1 and 1 'prepared by the method of the invention show better therapeutic efficacy for systemic infections with gram-negative bacteria, in particular Pseudomones eeruginosa, than compounds A and C and compounds E and F, which are commercially available synthetic antibacterial agents and compounds G and H and J, which are commercially available antibiotics.

3. Compounds 1 »Γ, prepared by the method of the invention, are clearly superior in terms of in vivo therapeutic efficacy to Gram positive bacteria than Compound D. Compounds 1 and 1 'have clearly superior in vivo therapeutic efficacy to grempositive bacteria including Pseudomones aeruginosa in comparison with compound D.

4. The ethyl ester of compound 1, prepared by the process of the invention, is useful as an intermediate for the synthesis of compounds 1 and 1 ‘. In addition, it has improved antibacterial activity in vivo against both Gram-positive and Gram-negative bacteria.

Example

In vivo therapeutic efficacy

Compounds 1 and D were tested as follows for therapeutic efficacy in ascending Pseudomones aeruginosa # 12 kidney infection in mice. In Table III, the results obtained are obtained with an ED g of ₀ mg / kgZ.

Experimental method:

Female mice (ddY-S) weighing 22 to 30 g are anesthetized by intravenous injection of sodium pentobarbital at a dose of 50 mg / kg. A small overcap section infects the bladder with 0.1 ml (1:10 000 dilution) Pseudomones aeruginosa # 12, which is cultured for 20 hours in tryptic soy medium, using a 0.25 ml injection with a 0.25 mm needle. Mice are prevented from accessing drinking water from one day before injection to one day after infection. Mice are treated twice daily for 3 days, starting on the day of infection. On the fifth day after infection, the kidneys were harvested to detect the presence of bacteria, sectioned and placed on King A agar where they were incubated overnight at 37 ° C. If no bacteria are found, this is considered to protect against ascending kidney infection. The ED50 values are calculated by probation / detection / analysis.

Table III

Efficacy in vivo on ascending kidney infection caused by Pseudomones aeruginosa # 12 in mice

Compound Administration ≥50 (50 s / kg) after 2.4

D. The results in Table III show that the therapeutic efficacy of Compound 1, prepared by the method of the invention, for the ascending Pseudomones aeruginosa kidney infection is clearly superior to Compound D.

235546 20

Example D

Acute toxicity

A solution containing one of the compounds 1, 1, 2, and 3 at various concentrations is administered orally to male mice (ddY) (4 to 8 in each group) at a dose of 0.1 ml of no .0 g body weight. After 7 days, the number of dead mice is counted. The mean lethal dose (LD 50, mg / kg) is calculated according to the Behrens-Keerber method. The results are shown in Table IV.

Table IV

Acute toxicity in mice

Compound ^LD 50 mg / kg 1 greater than 4000 1 ' greater than 4,000 ⁺ 2 greater than 2,000 ⁺ (B) 210 C greater than 2 000 D greater than 2 000 E 1 516 F greater than 5 000 G greater than 4000 H greater than 5 000 J 3 000

calculated for carboxylic acid

Table IV shows:

1. Compounds 1, 1 'and 2 prepared by the process according to the invention are extremely low toxic.

2. Compound B, which is derived from compound 1 prepared by the process of the invention by introducing a methyl group at the 4-position of the 1-plperazine group of compound 1, has an equivalent or greater antibacterial activity than the compounds of the invention, as shown in Tables I and II, but my extremely high toxicity.

Example £

Subecute toxicity

Compound 1 is orally administered to 6 female mice (JCL-LCR strain) having a mean body weight of 20 g, at a dose of 2 g / kg once daily for 14 days. Body weight of each mouse is measured during the test period. On the fifteenth day, mice are hematologically examined !. The mice are then sacrificed, the organ weights are blotted and the organs examined hi-stop. The following facts were found:

There were no abnormalities in body weight, hematology and histopathological observation with respect to the control group in the Compound 1 group prepared according to the invention. This postpones the high safety of Compound 1, prepared by the process of the invention.

Example F

Plasma level

An adult dog (Beagle), weighing 12 kg, is orally administered a capsule containing Compound 1 in an amount of 25 rag / kg with 200 ml of milk. Blood samples are taken by vein at 0.5, 1.2, 3, 6, 8 and 10 hours after challenge. Samples are individually centrifuged to separate plasma.

The drug level is determined on thin-layered plates using Esoherichia coli Kp as an indicator organism.

The results obtained are shown in Table V.

Table V.

Plasma level

Compound 0,5 1 Time after administration / h 10 2 3 6 8 1 0,6 2,4 5,5 5,9 4.2 3.7 2.4

Note: The numbers in Table V indicate plasma level / concentration / in µg / ml.

The results in Table V show that:

1. Compound 1, prepared by the method of the invention, is well and absorbed in the body by oral administration. The plasma concentration of these compounds is kept high for a relatively long time.

Compound 1 exhibits greater plasma concentrations than MIC values (see Table 1) for most bacteria within 1 to 10 hours after administration. For example, the plasma concentration (5.9 µg / ml) of Compound 1 is about 8-fold higher than the MIC values on pseudomones eeruginose # 12 and Staphylocoecus Aereue # 50,774 and about 6-fold higher than the MIC value on Esoheriohia coli P-5101.

2. Compound 1 has such a high plasma concentration and antibacterial efficacy that at low dosages it gives the best results in the treatment of systemic infections caused by various bacteria.

Example G

Urinary excretion / urinary secretion /

Urine excreted by the dog of Example P is collected for 24 hours. Compound 1 is determined in the collected urine as in Example F. The results are shown in Table VI.

• 22

Table VI

Urinary excretion

Compound Concentration Zjug / ml / Regeneration /% /

606 40.7

The results in Table VI show:

1. The urinary excretion of Compound 1 prepared by the method of the invention is relatively good: approximately 40% of the orally administered compounds are excreted in the urine within 24 hours of administration.

2. The concentration of Compound 1 in the urine (606 µg / ml) is approximately 51-6,000 times higher than the MIC (0.1-12.5 µg / ml) for the various bacteria listed in Table I.

3. Compound 1 exhibits the best effects at low doses in the treatment of urinary tract infections caused by various bacteria.

As exemplified in Tables I to VI, the compounds prepared by the process of the invention, and in particular compounds 1 and 1 ', show the best therapeutic effects on experimental infection by Gram positive and Gram-negative bacteria. When administered orally, these compounds maintain high plasma and urine levels for a sufficient period of time. In addition, they have low toxicity. Thus, these compounds are effective at low times in urinary tract infections and systemic infections caused by various bacteria.

In contrast, the known compounds A and C are clearly inferior in entibacterial activity in vitro as well as in vivo on gram-positive and gram-negative bacteria, as shown in Tables I and II.

Compound D is clearly worse than compounds 1 and 1 ', prepared by the method of the invention, in the therapeutic effects of ascending kidney infection caused by Pseudomonas aeruginosa. Nalidixic acid (compound E) and pipemidic acid (compound F), a commercially available synthetic antibacterial agent, and Carindacillin (compound G), ampicillin (compound H) and oephalexin (compound J), which are commercially available antibiotics, are clearly worse than compounds 1 and 1 * in therapeutic effects (see Table II) in vivo on gram-negative bacteria, in particular Pseudomonas aeruginosa.

Claims (3)

A process for the preparation of 1-ethyl-6-halo-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8-naphthyridine derivatives of the general formula I SUBJECT OF THE INVENTION (II) wherein X is fluorine or chlorine e R ₂ is hydrogen or alkyl having 1 to 6 carbon atoms, or netoxickýoh, pharmaceutically acceptable salts, characterized by reacting a compound of formula II / X η, -Ν ΓΤ Ν ^J \ _ / X where my above meaning and where it means R 1 is a hydrogen atom or a protecting group, R 1 is a carboxyl group, a group of the general formula -COOR, or a group R 6, where is R 1 is cyano, carboamoyl, amidino or a group of formula -C = NH AND O - R R is a C 1-6 alkyl group, with an ethylating agent, and the reaction product in which R 1 is R 2 is hydrolyzed or deprotected from the product in which R 1 is a protecting group and optionally the reaction product is converted to a non-toxic, pharmaceutically acceptable salt. 2. Method according to claim 1 for preparing a derivative of 1-ethyl-6-helegen-1,4-dihydro-4-oxo-7 - / - piperazinyl / -1, 8-nafthyridlnu of formula I wherein X and R ₂ have the or a non-toxic, pharmaceutically acceptable salt thereof, which comprises reacting a compound of formula (II) wherein X and R ^ are as defined in point (1) and wherein R R is a carboxyl group or a group of the formula -COOR, wherein R is as defined in item 1, and an ethylating agent, and then deprotecting the reaction product when R 1 is a protecting group and optionally converting the reaction product to its non-toxic pharmaceutically acceptable salt. 3. The process of item 1 for preparing a 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) -1,8-naphthyridine derivative of the formula I wherein X is fluorine and Rg is as defined in claim 1, or a non-toxic, pharmaceutically acceptable salt thereof, characterized in that a compound of formula IX is reacted wherein X is fluorine and Rj is as defined in point 1 B is carboxyl or a group of the formula -COOR, where R is as defined in point 1, with an ethylating agent, and in the case where R 1 is a protecting group, the protecting group is then cleaved and optionally the reaction product &gt; converted to a non-toxic pharmaceutically acceptable salt thereof. ‘