NO750325L - - Google Patents

Description

Procedure for the manufacture of penicillins.

The present invention relates to the production of new penicillins with the formula:

where R is cyclohexadienyl, cyclohexenyl, cyclohexyl or isobutyl, and A is a polycyclic nitrogen-containing heteroaromatic ring, and non-toxic salts thereof.

The penicillins with formula (I) produced according to the invention are characterized by the fact that the polycyclic heteroaromatic ring represented by the symbol A has at least one hydroxy group as illustrated in formula (I), preferably in a neighboring position to the carbon atom of which 6-(α-aminoacylamido) -the penicillanic acid group with the formula:

where R is as indicated above, is bound. In the event that the hydroxy group is able to assume a tautomeric form such as a keto-enol form, it may be present in the keto form (0=CC^) •

Examples of the polycyclic nitrogen-containing heteromaromatic ring A are quinoline, isoquinoline, cinnoline, naphthyridine, quinoxaline, pyrazolopyridine, pyridopyrimidine, etc. Among these, a naphthyridine ring is preferred.

The ring A can, in addition to at least one hydroxy group as indicated above, have any other substituents such as, for example: lower alkyl, lower alkoxy, lower alkanoyl, lower alkoxycarbonyl, lower alkyl-thio, mercapto, lower alkoxymethyl, halogen, cyano, nitro, lower alkylsulfonyl, arylsulfonyl, sulfamoyl , carbamoyl, aryloxycarbonyl-amino, acetoacetylamino, lower alkylamino, di-loweralkylamino, liuiOyvin—lavoXSoilCyl , luvélt a J-KfeJHy i , cxj. yy. , cyCiO-xavuieaiKyi , condensed cyclo-lower alkylene, etc.

The non-toxic - pharmaceutically acceptable salts of the penicillins (I) are e.g. the inorganic salts such as sodium, potassium, ammonium, calcium and magnesium salts, and the organic salts such as diethylamine, triethylamine, N,N'-dibenzylethylenediamine, diethanolamine, pyrrolidine, morpholine and procaine salts.

The α-carbon atom on the penicillin side chain (to which the acyl group is bound) is an asymmetric carbon atom, and the compounds produced according to the invention can therefore exist in two optically active isomeric forms (i.e. the D- and L-diastereoisomers) as well as in The DL form which is a mixture of the two optically active forms; while

all such isomeric forms of the compounds are covered by the invention, but the D(-) form is preferred. The present invention also includes esters which can be easily hydrolysed to the corresponding free acids by chemical or enzymatic hydrolysis.

It is well known that 6-(α-aminoacylamido)-penicillanic acid derivatives such as 6-(α-amino-phenylacetamido)-penicillanic acid (ampicillin), 6-(α-amino-p~hydroxy.phenylacetamido)-penicillanic acid (amoxycillin ), 6-(α-amino-thienylacetamido)-penicillanic acid, 6-(1-amino-cyclohexane-carboxamido)-penicillanic acid (cyclacillin), 6-(α-amino-isothiazolyl-acetamido)-penicillanic acid and 6-[α- amino-2-(1,4-hexadienylacetamido)]-penicillanic acid (epicillin) inhibits the growth of various gram-positive and gram-negative bacteria. In particular, ampicillin has excellent chemotherapeutic properties. However, these compounds do not exert any particular antimicrobial activity against Pseudomonas. On the other hand, there is a tendency for infections caused by Pseudomonas to increase. Recently, some penicillin antibiotics effective in treating Pseudomonas infections such as "Carbenicillin" and "Sulfocillin" appeared on the market, but their activity against Pseudomonas is not sufficiently strong. In US patent 3-433,784 some N-acyl derivatives of aminobenzylpenicillin (ampicillin) are indicated. However, their activity against Pseudomonas is not that high, and the antimicrobial activity against other Gram-negative bacteria is rather low. In German publication document 2.165-462, some N-acyl derivatives of aminobenzylpenicillin are indicated. But groups of 'for-

v

bonds where the symbol R is other than phenyl are not indicated. IN

In Japanese unexamined patent No. 48-92391, analogous penicillms to those of formula (I) are indicated. The symbol A is, however, limited to a monocyclic nitrogen-containing heteroaromatic ring. Compared with the antibacterial activity of the penicillins in the Japanese patent, the antibacterial activity of the penicillins (I) is stronger, especially against Escherichia coli, Proteus vulgaris and Klebsiella pneumoniae.

The pencillines (I) produced according to the invention exert an excellent antibacterial activity against gram-positive and gram-negative bacteria, especially against Pseudomonas aeruginosa. They are thus useful as antibacterial agents, particularly in the treatment of infections caused by Gram-positive and Gram-negative bacteria including Pseudomonas aeruginosa.

Accordingly, it is a main object of the present invention to provide the penicillins (I) and their non-toxic salts which are useful as antimicrobial agents.

According to the present invention, the penicillin (I) is prepared by reacting a carboxylic acid with the formula: where A is as stated above, or a reactive derivative thereof, with a compound of the formula:

where R is as above, or its derivative.

The reaction between the compound (II) or its reactive derivative, and the compound (III) or its derivative is usually carried out in an inert solvent such as a polar solvent (e.g. dichloromethane, chloroform, acetone, tetrahydrofuran, dioxane, acetonitrile, methylisobutyl ketone, ethanol , dimethylformamide, dimethylacetamide, dimethylsulfoxyd, sulfone, hexamethylphosphoric triamide, water), a non-polar solvent (eg benzene, toluene, petroleum ether, n-hexane) or mixtures thereof. In some cases, an aqueous medium can be used. The reaction temperature is not limiting and is usually below 50°C.

The reactive derivative of the carboxylic acid (II) on the carboxyl group includes e.g. acid halides, acid anhydrides, mixed acid anhydrides, acid azolides, acid azides and active esters. Examples of acid azolides are those prepared from imidazole, substituted imidazole, dimethylpyrazole, triazole, tetrazole, etc. The active esters can be cyanomethyl ester, p-nitrophenyl ester, 2,4-dinitrophenyl ester, trichloro-phenyl ester, pentachlorophenyl ester, methanesulfonyl ester, l-hydroxy ~2(1H)-pyridone, N-hydroxysuccinimide, N-hydroxydiphthalimide, etc.

When the carboxylic acid (II) is used in the form of a free acid, the amidation with the compound (III) or its derivative can preferably be carried out in the presence of a coupling reagent such as N,N'-dicyclohexylcarbodiimide, N-cyclohexyl-N'-morpholinoethylcarbodiimide, triphenylphosphine , 2-ethyl-5-(m-sulfonyl)-isdxazolium hydroxide internal salt or carbonyldiimidazole.

When the mixed acid anhydride is prepared to activate the carboxylic acid (II), the following method can be recommended. A molar amount of the carboxylic acid (II) reacts with approx. 2 molar amounts of a lower alkoxycarbonyl halide (e.g. ethyl chloroformate, isobutylchloroformate) or a lower alkanoyl halide (e.g. pivaloyl chloride) in the presence of approx. 2 molar amounts of a base to obtain a mixed acid anhydride of the formula: where Z is an acyl group, and A is as indicated above. The product of the amidation using such a mixed anhydride can be represented by the formula:

where A, R and Z are as indicated above, which can be transferred to the corresponding penicillin (I) by treatment with an organic or inorganic base (e.g. sodium carbonate, potassium carbonate, sodium hydroxide, ammonia water, triethylamine, dimethylamine, potassium 2-ethylhexanoate). The transfer can also be carried out under acidic conditions, although basic conditions are usually preferred.

The derivative of the compound (III) can e.g. be salts, esters or N-substituted compounds thereof. Examples of the salts are salts of alkali metals (e.g. sodium, potassium), alkaline earth metals

(e.g. calcium, barium), organic bases (e.g. trimethylamine, triethylamine) and organic sulfonic acids (e.g. toluenesulfonic acid, naphthalene sulfonic acid, tetrahydronaphthalene sulfonic acid).. Examples of the esters and the N-substituted compounds are as follows:

where R is as above, R 2 and R 3 are lower alkyl or lower alkoxy, R 2 and R 3 are lower alkyl, and R 6 is lower alkyl, aryl or a hetero ring.

Further examples of the ester unit in the esters of compound (III) are as follows: toluenesulfonyl ethyl ester, p-nitrobenzyl ester, benzyl ester, phenacyl ester, diphenyl methyl ester, substituted diphenyl methyl ester, trxtyl ester, benzoyioxymetny ester, lower alkanoyioxyrnetnyl ester, dimethylmethbylene amino ester, p-nitrophenyl ester, methylsulfonyl phenyl ester .

These esters can are used in salt form such as those obtained by using organic sulphonic acids (e.g. toluene sulphonic acid, tetrahydro-naphthalene sulphonic acid).

After the amidation with the compound (II) or its reactive derivative, these ester parts can be eliminated using methods known per se such as reduction or hydrolysis under such mild conditions that the (3-lactam ring of the penicillin core is not affected.

The following examples are given to further illustrate the invention.

Example 1

Preparation of 6-[D-2-(4-hydroxy-7-methyl-1,8-naphthyridine-3-carbonamido)-2-cyclohexylacetamido j-penicillanic acid:

To a solution of 2.16 g of 6-aminopenicillanic acid, 2.02 g of triethylamine and 1.33 g of dimethylaniline in 40 ml of dichloromethane was added dropwise 2.16 g of trimethylchlorosilah. After refluxing for 50 minutes, the mixture was cooled to -20°C To this mixture was added 2.33 g of D-α-cyclohexylglycyl chloride hydrochloride, and the mixture was stirred for 1 hour while the temperature was maintained at -20° C. After adding 3.01 g of 4-hydroxy-7-methyl-1, 8-naphthyridine.~3-carboxylic acid-N-hydroxysuccinimide ester, 2.26 g triethylamine and 55 ml dim et hy lf ormamide, the mixture was stirred at room temperature for 4 hours. Insolubles were removed by filtration, ether was added to the filtrate, and the precipitated crystals were collected by filtration.The crystals thus obtained were suspended in 100 ml of dichloromethane

with stirring, and the suspension was filtered, whereby 3.5 g of the triethylamine salt of the title compound was obtained.

Example 2

Preparation of 6-[D-2-(4-hydroxy-1,5-naphthyridin-3-ca rbon-amido)-2-(1-cyclohex:enyl)-acetaraido]-penicillansy re:

To a solution of 5>079f enacyl-6-[D-2-amino-2-(1--cyclohexenyl)-acetamido]-penicillanate hydrochloride and 2.02 g of triethylamine in 50 ml of dimethylformamide was added 3?00 g of 4 -hydroxy-1,5~naphthyridine-3-carboxylic acid-N-hydroxysuccinimide ester, and the mixture was stirred at room temperature for 3 hours. The reaction mixture was poured into 250 ml of ice-cooled aqueous 1% sodium bicarbonate solution with stirring. The precipitated white crystals were collected by filtration, washed with water and dried over phosphorus pentoxide under reduced pressure, whereby 5.60 g of phenacyl-6-[D-2-(4-hydroxy-1,5-naphthyridine-3-carbonamido) were obtained )-2-(1-cyclohexenyl)-acetamido]-penicillanate. The thus obtained phenacyl ester of the title compound was added to 150 ml of dimethylformamide, 2.3 g of sodium thiophenoxide was added, and then stirring was continued at room temperature for 1 hour. To this mixture was added 500 ml of acetone, and the precipitated solid was collected by filtration and washed with acetone and ether to give 4.28 g of the sodium salt of the title compound.

Example 3

Preparation of 6-[D-2-(4-bydroxy-1,5-naphthyridine-3-carbon-amido)-2-isobutylacet amido]-penicillanic acid:

2.45 g of 4-hydroxy-1,5 -naphthyridine-3-carbonyl chloride hydrochloride, and then 1.01 g of triethylamine with stirring. The mixture was stirred for 3 hours while cooling in an ice bath and for a further 1 hour at room temperature. The precipitated crystals were collected by filtration, washed with dichloromethane and dried under reduced pressure, whereby 3.76 g of the triethylamine salt of the title compound was obtained.

Example l 4

Preparation of 6-[D-2-(3-hydroxyquinoxaline-2-carbonamido)-2-(1-cyclohexenyl)-acetamido]-penicillanic acid:

To a solution of 1.90 g of 3-hydroxy-quinoxaline~2-carboxylic acid

1.78 g of carbonyldiimidazole was added to 30 ml of dimethylformamide, and the mixture was stirred at room temperature for 30 minutes. A solution of 4.54 g of 6-[D-2-amino-2-(1-cyclohexenyl)-acetamido]-penicillanic acid-triethylamine salt in 30 ml was added to this reaction mixture. dichloromethane, and stirring was continued at room temperature for 6 hours. After adding 3.64 g of a 50% n-butanol solution of potassium 2-ethylhexanoate followed by ether, the precipitated crystals were

collected by filtration, washed with acetone and dissolved in water. This aqueous solution was adjusted to pH 2 with 1 N hydrochloric acid while stirring and cooling. The precipitated crystals were collected by filtration, washed well with cold water and dried over phosphorus pentoxide under reduced pressure to give 3.32 g of the title compound.

Example 5

Preparation of 6-[D-2-(4-hydroxy-1,5-naphthyridine-3-carbon-amido)-2-(1,4-cyclohexadienyl)-acetamido]-penicillanic acid:

To 100 ml of dry dimethylformamide was added 1,896-[D-2-araino-2-(1,4-cyclohexadienyl)-acetamido-penicillanic acid and 0.92 g of triethylamine, and the mixture was stirred at room temperature for a while. £, i Lei lxla<=Lilxiivj of ,L,4h- puxVeiiSéi'u i+-åy <_»± oxy -x , j -u<jx <- i«y x iiixn - j ~ carboxylic acid-N-bydroxysuccinimide ester and then 20 ml of dimethylformamide, the mixture was stirred at room temperature for 3 hours. The mixture was poured into 1000 ml of acetone, whereby 1.48 g of the triethylamine salt of the title compound was precipitated as crystals.

Example 6

Preparation of 6-[D-2-(6-dimethylamino-4-hydroxy-1,5-naphthyridine-3-carbonamido)-2-(1,4-cyclohexadienyl)-acetamido]-penicillanic acid:

To a suspension of 3.49 g of 6-dimethylamino-4-hydroxy-.1,5-naphthyridine-3-carboxylic acid and 3.039 triethylamine in 80 ml of dichloromethane cooled to between -15° and -20°C, was added dropwise 3.249 ethyl chlorocarbonate, and the mixture was stirred at -15° to -20°C for 30 minutes. A cooled solution of 6.80 g of 6-[D-2-amino-2-(1,4-cyclohexadienyl)-acetamido]-penicillanic acid triethylamine salt in 40 ml of dichloromethane was added, and the resulting mixture was stirred for 2 hours. After adding a solution of 3>40 g of sodium bicarbonate in 200 ml of water, the mixture was shaken with 600 ml of ethyl acetate, and the water layer was separated. The aqueous layer was adjusted to pH 2 with 1 N hydrochloric acid while stirring and cooling. The precipitated crystals were collected by filtration, washed with water and dried over phosphorus pentoxide under reduced pressure, thereby obtaining 8.70 g of the ethyl pyrocarbonate derivative of the title compound. The product was dissolved in a mixture of 20 ml of dimethylformamide and 220 ml of acetone. After removing insoluble substances by filtration, 5.45 g of a 50% n-butanol solution of potassium 2-ethylhexanoate was added to the filtrate and stirred. Addition of 5p0 ml of ether to the mixture led to a refinement of crystals, which were collected by filtration, washed with ether and dried under reduced pressure, whereby 8.3 g of the potassium salt of the title compound was obtained.

Determined by the agar dilution method, the penicillins (I) showed the minimal inhibition concentrations against microorganisms which are indicated in Table 1.

In the above description, the term "lower" is used in connection with hydrocarbon groups, especially alkyl, to indicate a group with no more than 8 carbon atoms, preferably no more than 5 carbon atoms, and preferably no more than 3 carbon atoms. Typical examples of the term "aryl" include phenyl and naphthyl. The term "halogen"

can cover chlorine, bromine, iodine and fluorine.

Claims (12)

1. Procedure for the production of penicillins with the formula: where R is cyclohexadienyl, cyclohexenyl, cyclohexyl or isobutyl, and-A is a polycyclic nitrogen-containing heteroaromatic ring, and their non-toxic pharmaceutically acceptable salts, characterized in that a carboxylic acid of the formula: HO-A-COOH where A is as indicated above, or its reactive derivative, is reacted with a compound of the formula: where R is as above, or its derivative. 2. Method according to claim 1, characterized in that the reaction is carried out in a inert solvent. 3- Method according to claim 2, characterized in that dichloromethane, chloroform, acetone, tetrahydrofuran, dioxane, acetonitrile, methylisobutylketone, ethanol, dimethylformaraide, dimethylacetamide, dimethylsulfoxide, sulfone, hexamethylphosphoric triamide, water, benzene, toluene, petroleum ether or n-hexane, or mixtures are used as inert solvents hence. 4- Method according to claim 1, characterized in that the reaction is carried out at a temperature below 50°C. 5« Procedure according to claims 1-4? characterized in that acid halide, acid anhydride, an active azolide, acid azide or active ester are used as reactive derivative of the carboxylic acid. 6. Proceedings are carried out in accordance with requirements 1 - 5, characterized in that the derivative of the compound to be reacted with the carboxylic acid or its reactive derivative, 7« Procedure according to claim 1, characterized in that 6-[D-2-(4-hydroxy-1,5-naphthyridine-3-ca rbonamido)-2-(1-cyclohexenyl)-acetamido]-penicillanic acid is produced. 8. Method according to claim 1, characterized by the fact that one. prepares 6-[d-2-(4-hydroxy-1,5-naphthyridine-3-carbonamido)-2-isobutylacetamido]-penicic acid. 9- Method according to claim 1, characterized in that 6-[d-2-(3-hydroxyquinoxaline-2-carbonamido)-2-(1-cyclohexenyl)-acetamido]-penicillanic acid is produced. 10. Method according to claim 1, characterized in that 6-[D-2-(4-hydroxy-7-methyl-1,8-naphthyridine-3-carbonamido)-2-cyclohexylacetamido]-penicillanic acid is produced. 11. Method according to claim 1, characterized in that 6-[D-2-(4-hydroxy-1,5-naphthylidine-3-carbonamido)-2-(1,4-cyclohexadienyl)-acetamido]-penicillanic acid is produced. 12. Method according to claim 1, characterized in that mari produces 6-[D-2-(6-dimethylamino-4-hydroxy-1,5-naphthyridine-3-carbonamido)-2-(1,4-cyclohexadienyl)-acetamido]-penicillanic acid.