CS242274B1 - Method of 7-((1h-tetrazole-1-yl)acetamido)-3-(5-methyl-1,3,4-thiadiazol-2-yl)-thiomethyl)-3-cefem-carboxyl acid's preparation - Google Patents

Description

The present invention relates to a process for the preparation of 7 - [(1H-tetrazol-1-yl) acetamido] -3 - [(5-methyl-1,3,4-thiadiazol-2-yl) thiomethyl] -3-cephem- 4-carboxylic acids of formula I

N-CH; CO-t-1H Z ² N = CH

COOH fd

The compound of formula I is used in the form of salts or esters as a semi-synthetic antibiotic with a broad spectrum of activity against both Gram-positive and Gram-negative bacteria.

To date, this compound has been produced by acylating 7-amino-3 - [(5-methyl-1,3,4-thiadiazol-2-yl) thiomethyl] -3-cephem-4-carboxylic acid with the appropriate active acid derivatives (ΙΗ). -tetrazol-1-yl) acetic acid (see e.g. DE-OS 2 263 861 (1971); DE-OS 2 318 829 (1973); Japan Kokai 74 108 091 (1974); DE-OS 2 540 374 (1975)) (DE-OS 2,730,579 (1976)).

Another large group consists of procedures starting from 7 - [(1H-tetrazol-1-yl) acetamido] -2-acetoxymethyl-3-cephem-4-carboxylic acid and its sodium salt, respectively (see, e.g., J. Antibiotic 3 (23)). , 1970, 131; U.S. Pat. No. 3,516,997 (1968); DE-OS 1953 861 (1971); South African Patent 6,907,500 (1971); Fr. Pat. 2,068,419 (1969); DE-OS 2,617 442 (1976); DE-OS No. 2,607,681 (1975); Japan Kokai 7114,736 (1967); US Pat. 3,799,923 (1974).

In these processes, the starting compound, generally in the form of the sodium salt, is reacted with 2-mercapto-5-methyl-1,3,4-thiadiazole in phosphate buffer pH 6.4, with the addition of sodium bicarbonate, at 60 ° C. for about 6 h and the compound of formula I is isolated after completion of the reaction by acidifying the reaction mixture and extracting the product into ethyl acetate, concentrating and drying.

Another method for the preparation of DE-OS 2 436 771 (1974) is based on 7- [(ΙΗ-tetrazol-1-yl) acetamido] -3-halomethyl-3-cephem-4-carboxylic acid which reacts with 2-mercapto- 5-methyl-1,3,4-thiadiazole in dichloromethane in the presence of propylene oxide.

According to Fujisawa, the compound of formula I can be prepared by the reaction of 7 - [(1H-tetrazol-1-yl) acetamido] -3 - [(pyrimidinlum-1-oxide-2-yl) thiomethyl] -3-cephem-4 salts. carboxylic acids with 2-mercapto-5-methyl-1,2,4-thiadiazole in N, N-dimethylformamide in the presence of copper (II) chloride (Japan Kokai 74 117 487 (1973)).

Another Fujisawa patent describes the preparation of a compound of formula I by reacting 7 - [(1H-tetrazol-1-yl) acetamido] -3-azidomethyl) -3-cephem-4-carboxylic acid with 2-mercapto-5-methyl-1, 3,4-thiadiazole in phosphate buffer pH 6.4 and with the addition of sodium bicarbonate.

Said processes for the preparation of the compound of formula I have several disadvantages from an industrial point of view. In virtually all of the above processes, a complicated method of product isolation is used, whereupon the reaction mixture is acidified, the product is extracted into ethyl acetate, the extracts are washed, dried and the compound of formula I is obtained after distilling off the ethyl acetate in vacuo. Such an isolated product generally does not meet the quality standards and must be further purified, which is associated with further losses.

This method of isolation also produces a large amount of wastewater with an increased salt content, which has a negative impact on the environment.

Another disadvantage of the processes starting from 7 - [(1H-tetrazol-1-yl) -acetamido] -3-acetoxymethyl-3-cephem-4-carboxylic acid is the need to prepare the sodium salt of this compound, since in the acylation of 7-aminocephalosporanoic acid The product is isolated as the free acid or as a trialkylammonium salt of (1H-tetrazol-1-yl) -acetic acid.

All these negative factors reduce production capacity and adversely affect the entire production economy.

The process for the preparation of the compound of the formula I according to the invention is based on the reaction of the salt of 7 - [(ΙΗ-tetrazol-1-yl) -acetamido] -3-acetoxymethyl-3-cephem-4-carboxylic acid of the formula II, N-CtyCO-NHN = CH o '

COOM

wherein M is a RWHNY type cation wherein R ¹ , R ² , R ³ is hydrogen, C 1 -C 6 alkyl, C 1 -C 6 cycloalkyl, or benzyl; with 2-mercapto-5-methyl-1,3,4-thiadiazole in phosphate buffer, at a pH of the reaction medium of 5.0 to 6.4, preferably at a pH of 5.25 + 0.15 and at a temperature of 40 to 80 ° C, preferably at a temperature of 60 to 63 ° C.

The process according to the invention is carried out by dissolving 1.0 to 1.4 moles of 2-mercapto-5-methyl-1,3,4-thiadiazole in a buffer solution, preferably in a phosphate buffer having an initial pH of 8.0 to 8 1, and 1.0 mole of the compound of formula II is added to the resulting solution.

After dissolution of the raw materials, the pH of the reaction medium drops, depending on the initial pH, to 5.0 to 6.4. When using a phosphate buffer with an initial pH of 8.0 to 8.1, the pH drops to 5.4.

The reaction solution is heated to a temperature of 40 to 80 ° C, preferably to a temperature of 60 to 63 ° C, and is maintained at this temperature until the reaction is complete. The reaction time is between 2 and 8 hours, depending on the reaction temperature. At a reaction temperature of 60-63 ° C, the reaction time is 5.5 hours.

After completion of the reaction, a water-miscible organic solvent such as methanol, ethanol, tetrahydrofuran, Ν, Ν-dimethylformamide and the like, preferably acetone, is added to the solution, and the reaction mixture is acidified while still warm with a strong mineral acid, preferably concentrated hydrochloric acid. to a pH of 2.1 to 2.2.

The reaction mixture was then cooled to 20 ° C over 2-3 hours. The product, which begins to precipitate from the solution at about 50 ° C, is filtered off after cooling to 20 ° C, washed on the filter with distilled water, ethanol and finally ether.

The washed product is dried to constant weight, preferably under vacuum and at a maximum temperature of 40 ° C. The compound of formula I can be purified by crystallization from a water-miscible water-miscible solvent, e.g. methanol, ethanol, dioxane, tetrahydrofuran, N, N242274

dimethylformamide, preferably acetone, wherein the ratio between water and organic solvent is 1: 1 to 1: 5, preferably 1: 4 using a water-acetone mixture.

A more preferred method of purifying the compound of Formula I without thermally stressing the purified compound is to dissolve the contaminated compound in a 1: 1 to 2: 1 mixture of N, N-dimethylformamide-methanol, and to purify the solution by adding a suitable sorbent, e.g. The mixture is filtered, bleached with clay, activated charcoal and the like, filtered and the purified compound of formula I is separated from the filtrate by the addition of an additional 2-6 parts of methanol, filtered and dried, preferably under vacuum.

An advantage of the process according to the invention is that the reaction is based on ammonium and ammonium, respectively. substituted ammonium salts of 7 - [(1H-tetrazol-1-yl) acetamido] -3-acetoxymethyl-3-cephem-4-carboxylic acid (compound of formula II), which is prepared according to known procedures (e.g. 239 416) and is isolated directly from the reaction mixture, so it is not necessary to pre-prepare the free acid or its sodium salt, which are used as feedstock in other nucleophilic substitution procedures.

The process according to the invention further allows, in obtaining the same reaction yields and better product quality, to use a much simpler method of isolation whereby the product (compound of formula 1j is isolated directly from the reaction mixture after addition of a water-miscible organic solvent and subsequent acidification of the solution.

The result of this process is technology with minimal waste generation, as the extraction of the product into ethyl acetate has been bypassed, which is both technologically and wastewater intensive. After acidification, the product, which is practically insoluble in the reaction mixture, is filtered off while the impurities remain in solution. It is not necessary to further purify the recovered product before further processing.

Further, the invention is described by way of examples, which describe in more detail some of the possibilities of preparation and purification of the compound of formula I without limiting the scope of the invention in any way.

Example 1

Weigh 9,07 g of potassium dihydrogen phosphate (KH2PO4} into a 1 liter graduated flask, dissolve in distilled water and make up to the mark to make stock solution A.

Weigh 23,20 g of potassium hydrogen phosphate (K2HPO4) into a 2 liter graduated flask, dissolve in distilled water and make up to the mark to make stock solution B.

To a 2.5 L three necked flask equipped with a stirrer, thermometer and reflux condenser was measured 1,520 mL of stock solution B and added enough stock solution A so that the pH of the solution after mixing was 8.0-8.1. The approximate consumption of solution A is 80 ml. The contents of the flask are heated to 60-63 ° C with stirring and 30.6 g (0.232 mol) of 2-mercapto-5-methyl-1,3,4-thiadiazole are dissolved in the solution at this temperature, followed by 96.8 g (0.200 moles). molj of 7 - [(1H-tetrazol-1-yl) acetamido] -3-acetoxymethyl-3-cephem-4-carboxylic acid triethylammonium salt.

After dissolution of the raw materials, the pH of the solution drops to about 5.4. The reaction mixture is stirred at 60-63 ° C for 5.5 h. 200 ml of acetone are then added to the solution and at 55-60 ° C the solution is acidified with concentrated hydrochloric acid to pH 2.1-2.2 ( approximately 35 to 37 milliliters).

After acidification, the solution was further stirred and cooled to 20 ° C over 2 h. During cooling, at a temperature of about 50 ° C, the product starts to precipitate out of solution. After cooling to 20 ° C, the product is filtered off, washed with 2X 100 ml distilled water, 2X 100 ml ethanol (99.8%) and finally with 2 X 50 ml dried ether.

The washed and well aspirated product is dried to constant weight, preferably under vacuum and at a maximum temperature of 40 ° C. 50 g (55%) of the compound of formula I having a melting point of 189 DEG-190 DEG C. (with decomposition) is obtained: for C14H14N8O4S3 (m.p. 454.51 g. Mol ^-1 ) calculated:

H, 3.10; N, 24.66.

14.08% O, 21.17% S;

found:

27.3% C, 3.4% H, 24.3% N, 13.9% O; 21,2% S.

The IR spectrum of the compound of formula I in the nujol suspension shows characteristic bands at 3,280 cm ^-1 [—NH-], 3-140 and 3,075 cm ^-1 (tetrazole ring —N = N— and —C = N—), 1770, 1715 and 1550 cm ^-1 (C = O of lactone, acid, amide I and amide II j.

Purity of the prepared compound of formula I:

The absorbance of 1 g of the compound of formula I dissolved in 10 ml of a 0.5 mol / L sodium bicarbonate solution, measured at 400 nm, was 0.16. Content determined by liquid chromatography (LCj) was 98.7%

The procedure is as in Example 1, except that after dissolving 2-mercapto-5-methyl-1,3,4-thiadiazole in the buffer, 0.2 mol of the diisopropylammonium salt of the compound of formula II is added to the solution and after the reaction is complete. 280 mL of tetrahydrofuran was added to the reaction mixture.

The further isolation procedure is again identical to the 2427 step in Example 1. 46.4 g (51 percent) of the compound of formula I were obtained. The structure was confirmed by melting point, elemental analysis and IR spectroscopy. The absorbance (determined as in Example 1) was 0.22 and the LC content was 95.5%.

Example 3

The procedure was as in Example 1, except that after dissolving 2-mercapto-5-methyl-1,3,4-thiadiazole in the buffer, 0.2 mol of the N, N-dimethylbenzylammonium salt of the compound of formula II was added to the solution and after the reaction time, 250 ml of methanol were added to the solution.

A further isolation procedure is identical to Example 1. 42.7 g (47%) of the compound of formula I were obtained. The structure was again confirmed by melting point, elemental analysis and IR spectroscopy. The absorbance (determined as in Example 1) was 0.27. The LC content was 95.1%.

Example 4

In a 2 L stirrer flask, 400 g of the impure compound of formula I (with an initial absorbance of 0.62 and an LC content of 93.7%) was dissolved in a mixture of 600 ml of N, N-dimethylformamide and 600 ml of methanol. After clarifying the solution, 5 g of activated carbon were added, the mixture was stirred for 10 minutes and then filtered into a 5 L beaker. An additional 1,800 ml of methanol was added to the filtrate, the solution was stirred, cooled to 5 ° C and left at this temperature for 5 hours.

The separated purified compound of formula I was then filtered off, washed with 2X 200 ml ethanol (99.8%) on the filter and finally with 2X 200 ml dried ether. After vacuum drying at max. 40 ° C, 324 g (81%) of the purified compound of formula I were obtained.

The structure was again confirmed by melting point, elemental analysis and IR spectroscopy.

Purity: the absorbance (determined as in Example 1j was 0.35 and the LC content was 97.25%).

Claims (6)

SUBJECT A process for the preparation of 7 - [(1H-tetrazol-1-yl) acetamido] -3 - [(5-methyl-1,3,4-thiadiazole) HNALEZE -2-yl) -thiomethyl-3-chloro-4-carboxylic acid of formula I, N-CH 2 CO-NH X ² N = CH (D) characterized in that 1 molar of the salt of 7 - [(1H-tetrazol-1-yl) -acetamido] -3-acetoxymethyl-3-cephem-4-carboxylic acid of the general formula II, n-ch .alpha.-nhN-CH2 C 14 O-CO-CH 3 COOM wherein M represents ammonium, respectively. substituted ammonium cation R ¹ R ² R ³ HN ⁺ , where R ¹ , R ² , R ³ is hydrogen, C 1 -C 6 alkyl, C 3 -C 6 cycloalkyl or henzyl, reacts with 1.0 to 1.4 molar parts of 2-mercapto-5- methyl () -1,2,4-thiadiazole in phosphate buffer medium, at pH 5.0 to 6.4, at 40 to 80 ° C, for 2 to 8 hours, and the resulting compound of formula I is isolated from the solution by adding a miscible organic solvent with water, acidification with a strong mineral acid to a pH of 2.1 to 2.2, slowly cooling the solution, filtering, drying, preferably under vacuum, with optional purification. 2. The process according to claim 1, wherein the reaction is preferably carried out in a phosphate buffer medium at a pH of 5.25 ± 0.15. 3. The process according to claim 1, wherein the reaction is preferably carried out at a temperature of 60 to 63 [deg.] C. for a reaction time of 5.5 hours. 4. The process according to claim 1, wherein methanol, ethanol, tetrahydrofuran, N, N-dimethylformamide, dimethylsulfoxide, dioxane, preferably acetone are used as the water-miscible organic solvent to be added to the reaction mixture prior to acidification. 5. Process according to claim 1, characterized in that sulfuric acid, phosphoric acid, hydrobromic acid or hydrochloric acid are used as the strong mineral acid suitable for acidifying the reaction mixture. 6. The process of claim 1 wherein the compound of formula I is purified by a process without thermal stress by dissolving said compound in a 1: 1 to 2: 1 mixture of N, N-dimethylformamide-methanol, resulting solution. The mixture is purified by a suitable sorbent, such as bleaching earth, activated carbon and the like, filtered and the purified compound of formula I is precipitated by addition of an additional 3-6 parts of methanol, filtered and dried.