DK143031B - METHOD OF PREPARING 7-AMINOCEPHALOSPORANIC ACID - Google Patents

Description

14303 1

The present invention relates to a process for the preparation of 7-aminocephalosporanoic acid by in situ preparation and recovery of a derivative of cephalosporin C and subsequent cleavage thereof.

Methods for recovering cephalosporin C from a culture medium are described in the disclosures to U.S.A. patents Nos. 3,093,638 and 3,094,527, wherein cephalosporin C is adsorbed on an adsorbent instead of solvent extraction. While lower alkyloxycarbonyl or aryloxycarbonyl or (lower) alkylcarbamoyl or aryl carbomoyl-cephalosporin C derivatives are not disclosed scan formed "in situ" in the cephalosporin C culture medium, or as useful in extracting cephalosporin C from the nutrient medium or as useful as starting material preparation of 7-ACA are some of these compounds described in the patent literature (English Patents Nos. 1,014,883 and 1,064,495 as well as U.S. Patents 3,227,707 and 3,227,712 as antibiotics). Several methods of chemically cleaving cephalosporin C or some of its derivatives are described in the patent literature (U.S. Patents Nos. 1,188,311, 3,234,223 and 3,124,576, and English Patent Nos. 1,041,985). None of these methods use N- (lower) alkyloxycarbonyl or N- (lower) alkyl or arylcarbamoylcephalosporin C and a silyl ester thereof as starting material.

7-Aminocephalosporanoic acid (7-ACA) having the formula: V ^ o N ___ CH_-O-C-CH.

CO2H

is an extremely valuable intermediate in the preparation of a large number of semi-synthetic cephalosporanoic acid antibacterial agents. Due to the difficulties of total synthesis of 7-ACA on a large scale, this compound is prepared in practice by the chemical degradation of naturally occurring cephalosporanoic acid, i.e. cephalosporin C produced by fermentation. Most 7-ACA is made from cephalosporin C (U.S. Patent 3,093,638) having the formula:

H OH S

H, N-C- (CH _) - -C-N-f> £ \ L · 3 q C0 «H„ // - N. CH2-0-C-CH3 o / co2h

The preparation of 7-ACA by the methods available today is fraught with difficulties ranging from the fermentation to the chemical decomposition of cephalosporin C. Low yields of 7-ACA have made it difficult for cephalosporanoic acids to occupy this additional space within the antibiotic. therapy. For this reason, the method of the present invention represents a significant improvement over the prior art.

Cephalosporin C is characterized by an amino acid function in the side chain. The amino acid exists in the form of a zwitterion in aqueous solution and as such it is highly water soluble. Due to its highly ionic nature, it is extremely difficult to recover by solvent extraction from the culture medium. The recovery method used today involves adsorption of the crude cephalosporin C from the culture medium onto a suitable adsorbent, e.g. charcoal, an ion exchange resin or the like followed by elution, concentration and precipitation at the isoelectric point or by salt formation (U.S. Patent No. 3,094,527). The low efficiency of the complexity of each step of this process makes it very difficult to prepare 7-ACA.

Most 7-ACA is produced by partial degradation of cephalosporin C or its derivatives by chemical agents (U.S.

3,124,576, 3,188,311 and 3,234,223).

Again, these methods provide practical yields that are undesirably low. Furthermore, these methods must inevitably scan starting material using a purified form of cephalosporin C which is difficult to obtain.

The process of the present invention for the preparation of 7-ACA goes through a derivative of cephalosporin C which need not be present in a purified form and unexpectedly high yields of 7-ACA are obtained.

The process of the present invention is characterized by the characterizing part of claim 1, and it generally comprises the following steps wherein the preferred disclosures relate to preferred embodiments of the invention which provide particularly high yields of 7-ACA: (A) Addition of an acylating agent , in the form of an isocyanate of the formula:

R - N = C = O

or a halogen formate of the formula:

ISLAND

II

X - C - O - R

Wherein R is alkyl of 1-10 carbon atoms, preferably ethyl, n-propyl, isopropyl, n-butyl or isobutyl or a group of the formula: wherein n is an integer from 1-6 when B in the formula III below is -OR, 23 and from 0-6 when B represents -NHR and R and R are the same or different and each represents H, Cl, Br, F, NO2, alkyl containing 1-10 carbon atoms or alkoxy containing 1 -10 carbon atoms, preferably hydrogen, and X represents chlorine, bromine or iodine, to an acid-incubated culture substrate, preferably pre-filtered, containing cephalosporin C, at a ratio of at least 2 moles of acylating agent per liter. mole of cephalosporin C, but preferably in a ratio of 2-10 moles of acylating agent per ml. mole of cephalosporin C, and especially preferably 5-8 moles of acylating agent per mole. mole of cephalosporin C, at a pH above 7, preferably ca. 8, at a temperature below 40 ° C, preferably from -5 to 20 ° C to form a derivative of cephalosporin C of the general formula:

H 0 H S

mo2c-c- (ch2) 3-c-n ... _ NH 0

c = o j-n s? —ch2-o-c-ch3 III

B O

CO 2 M

wherein M represents hydrogen or a metal or amine cation and B represents a group of the formula -NHR or -OR, R having the meaning given above, (B) recovering the derivative of cephalosporin c of formula III, preferably by extraction using of a water-immiscible organic solvent such as methyl isobutyl ketone, butanol, ethyl acetate or the like, preferably methyl isobutyl ketone, when B represents -OR and n-butanol, when B represents -NHR at a pH value of 1-3, preferably approx. 2, (C) mixing the compound of formula III with a silyl compound of formula: mf 'Sl'im \ ΚΛ L J <Rj R M 7- or R5 R6-Si-X v 17

K

Wherein R, R and R are hydrogen, halogen, (lower) alkyl, halogen

(lower) alkyl or phenyl, with at least one of the groups R, R and R

4 is different from halogen and hydrogen, R represents (lower) alkyl, m is 1 or 2 and X represents halogen or the group:

-N

Wherein R represents hydrogen or (lower) alkyl and R represents hydrogen, (lower) alkyl or the group: R5 R6-Si--

I 7 R

preferably dimethyldichlorosilane or trimethylchlorosilane, under anhydrous conditions in the presence of an acid-deactivating tertiary amine which may be triethylamine, dimethylaniline, quinoline, lutidine or pyridine, in an inert solvent which may be methylene chloride, dichloroethane, chloroform, to produce the corresponding sily ester of compound III, (D) admixing the sily ester with a halogenating agent which is preferably phosphorus pentachloride, phosphorus pentabromide, phosphorus trichloride, phosphorus tribromide, oxalyl chloride, p-toluenesulfonyl halide, phosphorus or oxychloride, ratio of at least one mole of halogenating agent per moles of silyl ester, preferably ca. 2 mol, under anhydrous conditions in an inert solvent such as methylene chloride, dichloroethane, chloroform, tetrachloroethane, nitromethane, diethyl ether or the like in the presence of an acid-deactivating tertiary amine in the form of triethylamine, diethylaniline, quinoline, lutidine, pyridine or the like at temperatures below 0 ° C, preferably in the range of -40 ° C to -60 ° C, to produce in solution of the corresponding imino halide, (E) mixing said solution of imino halide with an alcohol, preferably in the form of aliphatic alcohols containing 1-12 carbon atoms or phenylalkyl alcohols containing 1-7 carbon atoms at a temperature below 0 ° C, preferably -40 ° to -70 ° C to produce in solution of the corresponding imino ether, and (F) mixing said solution of imino ether under acidic conditions with water or an alcohol, in particular an aliphatic alcohol or a mixture of both to produce 7-aminocephalosporanoic acid.

The process of the invention provides unexpectedly high yields, both under laboratory conditions and on a commercial scale. The yields, which may be of the order of 50-70%, are attributed to the use of silyl esters on the carboxyl groups for the compounds of formula III. The silyl esters can be prepared and hydrolyzed to the acid again without loss of product, especially if the reaction takes place at temperatures below -20 ° C, preferably -40 ° to -70 ° C to form the imino ether. In addition, the use of cilyl esters instead of the esters used in the above patents simplifies the process, since the cilyl ester hydrolyses immediately during cleavage of the imino group double bond and avoids the separate step of cleavage of the 4-carboxylic acid esters by the known methods. .

The formation of the silyl ester occurs by reacting a silyl compound of formula IV or V under anhydrous conditions in an inert organic solvent with the compound of formula III or a salt thereof in the presence of an acid deactivating tertiary amine.

Inert solvents which may be used include methylene chloride, dichloromethane, chloroform, tetrachloromethane, nitromethane, benzene and diethyl ether.

Salts of Compound III which may be used include, among others, alkali metal and alkaline earth metal salts such as potassium, sodium, calcium, aluminum, etc. Also, anroonium and amine salts, preferably of tertiary amines, such as triethylamine, dibenzylamine, trimethylamine, N-methylmorpholine, pyridine, N-benzyl-ft-phenethylamine, 1-ephenamine, Ν, Ν'-dibenzylethylene diamine, dehydroabiethylamine, may be used. and N- (lower) alkyl-piperidines such as N-ethylpiperidine. Tertiary amine salts are preferred.

Acid deactivating tertiary amines which may be used include, inter alia, triethylamine, dimethylaniline, quinoline, lutidine and pyridine. Preferably, the amount of acid deactivating amine used is an amount equivalent to approx. 75% of the total acid developed during the process of the halogenating agent and halogen silane compound reacting with Compound III.

Silyl compounds of formulas IV and V which may be used are: trimethylchlorosilane, hexamethyldisilane, triethylchlorosilane, methyltrichlorosilane, dimethyldichlorosilane, triethylbromosilane, tri-n-propylchlorosilane, bromomethyl dimethylchlorosilane, tri-dimethylchlorosilane, -bromsilan, benzylmethylethylchlorsilan, phenylethylmethylchlorsilan, triphenylchlorosilane, triphenylfluorsilan, tri-o-tolylchlorsilan, tri-p-dimethylaminophenylchlorsilan, N-ethyltriethylsilylamin, hexaethyl disilazane, triphenylsilylamin, tri-n-propylsilylamin, tetraethyldi-hexamethyldisilazane, tetramethyldiethyldisilazan, tetramethyldiphenyl-disilazane, hexaphenyldisilazan and hexa-p-tolyldisilazane. The same effect is obtained by hexa-alkylcyclotrisilazanes or octa-alkylcyclo-tetrazilazanes. Other suitable silylating agents are silylamides and silylurides, such as trialkylsilylacetamide and bis-trialkylsilylacetamide.

Preferably, the imino compound is an imino chloride or bromide which can be prepared by reacting the silyl ester of Compounds III with a halogenating agent such as phosphorus pentachloride, phosphorus pentabromide, phosphorus trichloride, phosphorus tribromide, oxalyl chloride, p-toluenesulfonic acid chloride, or agents at temperatures, preferably below 0 ° C, such as 40 ° to _60 ° C.

8 143031

A very important step for obtaining high yields in the process of the invention is the formation of the imino ether by reacting the imino halide under anhydrous conditions with a primary or secondary alcohol at temperatures between -20 ° C and -70 ° C, preferably ca. -40 ° C to -70 ° C. Temperatures above -40 ° lead to a significant reduction in yield.

Alcohols that can be used to prepare the imino ethers from the imino halides include primary and secondary alcohols of the general formula R 2 OH, wherein R 2 represents (A) alkyl, containing 1-10 carbon atoms, preferably 1-3 carbon atoms such as ethanol, ethanol. , propanol, isopropanol, n-butanol, amyl alcohol and decanol, (B) phenylalkyl of 1-7 alkyl carbon atoms such as benzyl alcohol and 2-phenylethanol-1, (C) cycloalkyl such as cyclohexyl alcohol, (D) hydroxyalkyl of 2 -12 carbon atoms, preferably at least 3 carbon atoms such as 1,6-hexanediol, (E) alkoxyalkyl, containing 3-12 carbon atoms such as 2-methoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, (F) aryl-oxyalkyl having 3-7 carbon atoms in the aliphatic chain such as 2-p-chlorophenoxyethanol, (G) aralkoxyalkyl of 3-7 carbon atoms in the aliphatic chain such as 2- (p-methoxybenzoyloxy) ethanol, (H) hydroxy-alkoxyalkyl of 4-7 carbon atoms, such as diglycol. Mixtures of these alcohols are also suitable for preparing the imino ethers.

After formation of the imino ether from the imino halide, the iroino bond must be cleaved to produce 7-ACA. This is achieved by mild hydrolysis or alcoholysis. If the amount of acid-deactivating tertiary amine present during the process is an amount less than the acid produced by the silylation and halogenation, the cleavage is likely to occur simultaneously with the formation of the imino ether. However, if the amount of acid deactivating amine is more than the acid produced, the cleavage step will require careful addition of an amount of H + to effect the cleavage.

7-ACA is recovered from the reaction mixture by adjusting the pH of the mixtures to or near the 7-ACA isoelectric point, after which the 7-ACA is crystallized and collected by filtration.

In order to obtain the highest possible yields of 7-ACA, it is preferred to use high concentrations of the reactants. For the preparation of the silyl esters, e.g. 20% to 30%, preferably 25% by weight of compound III in an inert organic solvent and a base for best results. The silane is preferably used in excess, i.e. 10% to 60% above theoretical amounts.

A molecule of cephalosporin C derivative III has two reactive carboxylic acid groups capable of forming silyl esters. Therefore, for the silylation reaction, 1 mole III is equal to two weight equivalents.

Therefore, when compound III is treated with dichlorodimethylsilane, 1 molecule of compound III (two weight equivalents) is treated with at least 1 molecule (2 weight equivalents) dichlorodimethylsilane. Similarly, when compound III is treated with chlorotrimethylsilane, 1 molecule III (2 weight equivalents) is treated with at least two molecules (2 weight equivalents) chlorotrimethylsilane.

This allows solvents which are not completely dry to be used because traces of water are removed therefrom by reaction with excess silylating agent. Of course, the amount of silane compound required depends on whether one or both carboxylic acid groups of compound III are available for silyl ester formation. The reaction scheme is illustrated below:

Process progress in H OH

'"' Æ ho2c-c- (ch2) 3-c-n_j_S X 0 NH / L N CH2-0-C-CH. ·

»* O 'J

C = 0 · COpNs 1. (C * ® \ 5 ^ i x p vo

/ X X

'*'% x,

CH "/" X

/ \ I · I

CH, CH,

3 OH OH

π 1 »ts • -OCp- (CH_), -CN —-- / \ 0 NH -5 I" <j) = 0 J, _N -CH ^ OC-CH ^ / fcH? ^ X-0- (CHj Si '0H "

32 \ / \ O

. CH, CH, 13 3 in X-. Pci ^ --- rr * ψ 5 —x π I Cl s' -0-C-9- (CH_), -CelL- o

NH -5 I

/ yr. J- \ J-ge2- ° - ° -ge3 (ch J ^ i 6h2 To- \ CH "

/ \ O

CH CH3 / s \ O ^ ¥ —γ-Υ ^ \ ° ^

1-N J_CH-0-C-CH

// xr ^ 23 o I

co2h 11 143031

Process II

H OH

i "i S

H02C ~ C- (CH2) 3-C-N_j-S \ | ISLAND

NH, 1-N 1-GH2-O-C-CH

, / ys 3 G = 0 1 i CO Na CH3 'rTn OH s Λ

-0-δ-φ- <0Η2) 3 ^ -ά ^ N O

f _N, -CH -O-C-CH

/ 9 = o IT

(CH) "Si NH0 C-O- ^ C I ft (ch2) 3 o CH3 S._ PCI.," - ^ - v 5 ^ 7h Cl s

-0-0 - (^ - (ch2) ^ -c-n —— / N J

NH _N J-CH ^ -O-C-CH, / u f (CH) Si · O C-O- J ^ \ nh «

'Oh

(CH

I c J

CH, L_ r y-τηΑ ° γ · ° Η2 ′ 0 ′ ° C, I3 12 143031

Example 1

Preparation of sodium N-carbisobutoxycephalosporin C H OH S

ho2c- c - (ch2) 3 - C - N i-

NH S

Jr —— N Λ — ch7 - o - c - ch7 c-o y.

CO, Na CH, 2

-CH

qh / \ h3

Two thousand hundreds of liters of culture medium containing cephalosporin C were mixed with 108 kg of filter aid and 300 ml of silicon foam and then filtered at a pH of 6.9 at 10 ° C.

To the filtered medium was added sufficient oxalic acid to obtain a pH of 3.1. After this addition, the pH was adjusted to 2 with the addition of 30% sulfuric acid. 54 kg of fresh filtration aid was added and the mixture was filtered. The filtrate thus obtained was extracted with \ volume of methyl isobutyl ketone (MIBK) at a pH of 2 and then separated. The MIBK phase was discarded.

A quarter volume of acetone was added to the extracted medium and the pH was adjusted to 7.85 with a solution of sodium hydroxide.

2 kg of isobutyl chloroformate per 1000 liters of filtered medium was added slowly with stirring (a molar ratio of 5.9 moles of isobutyl chloroformate per mole of cephalosporin C). The pH was kept constant at 7.8 - 8.0 by the addition of 15% sodium hydroxide, and the temperature was kept in the range 0 - 10 ° C during the addition. Stirring was continued until the pH became constant without the addition of additional sodium hydroxide, for a period of approx. 2 hours.

The pH was adjusted to 2 by the addition of 13% sulfuric acid and the acylated medium was extracted with ½ volume of MIBK. The MIBK phase was washed with water and then concentrated to ca. 1/3 of the original volume at 36 ° C in vacuo. The water content of the concentrate was 0.2% (Karl Fisher's method).

The concentrate was cooled and a solution of sodium methyl hexanoate in MIBK was added to a pH of 4.8. The sodium salt of a carbisobutoxy-cephalosporin C was precipitated and collected by filtration. The precipitate was washed with MIBK, slurried in petroleum ether, filtered and dried in a vacuum oven at 40 ° C to 60 ° C to yield 7.2 kg of product. Examination of the remaining medium showed the presence of less than 1% cephalosporin C activity. The product collected was estimated to be 42% to 50% pure sodium n-carbisobutoxycephalosporin C. The product was of sufficient purity for subsequent preparation of 7-aminocephalosporanoic acid.

Example 2

Sodium N-carbisobutoxycephalosporin C (13.5 g) from Example 1, 45 ml of methylene chloride, 3.0 ml of dimethylaniline and 3.67 ml of triethylamine were mixed together. 6.2 ml of dichlorodimethylsilane was added with stirring at a temperature of 28 ° C. The solution was stirred for 40 minutes. Next, the solution was cooled to -60 ° C and 12.0 g of phosphorus pentachloride dissolved in 100 ml of methylene chloride was added. An additional 11.0 ml of dimethylaniline was added while maintaining the temperature of the reaction mixture below -40 ° C. The temperature was steeply lowered to -73 ° C after two hours, and a mixture of 60 ml of methanol and 2.5 ml of dimethylaniline cooled to 78 ° C was added slowly. The temperature rose to -45 ° C. The mixture was stirred and cooled again to -50 ° C. After two hours, 55 ml of water was added, heated to + 90 ° C. The temperature rose to + 3 ° C. The mixture was cooled in an ice bath and stirred for four minutes. 22 ml. ammonia water was added over a period of eight minutes to a pH of 3.7. The mixture was stirred for several hours and then filtered. The precipitate was collected, washed with 50 ml of methylene chloride, then 40 ml of water, then 50 ml of methanol and finally 50 ml of acetone. The solid was dried to give 2.25 g of 92.5% 7-ACA.

Example 3

Preparation of Sodium N-Carbisobutoxycephalosporin C The procedure described in Example 1 was repeated, using a molar ratio of 4.5: 1 instead of a 5.9: 1 molar ratio of isobutyl chloroformate to cephalosporin C, and 10.4 was obtained. kg of product. Examination of the residual culture medium after extraction showed the presence of less than 14% cephalosporin C activity.

14 143031

Example 4 13.5 g of sodium N-carbisobutoxycephalosporin C prepared as described in Example 3, 50 ml of methylene chloride, 3 ml of dimethylaniline and 3.67 ml of triethylamine were mixed together. 6.2 ml of dichlorodimethylsilane was added with stirring at a temperature of 25-29 ° C. The solution was stirred for 30 minutes, then cooled to -60 ° C and 12.0 g of PCI, in 100 ml of methylene chloride was added. The temperature was kept at -40 ° C for two hours. The solution was cooled to -73 ° C and a solution of 60 ml of methanol and 2.5 ml of dimethylaniline cooled to -78 ° C was added. The temperature rose to -46 ° C. The temperature was kept in the range -45 ° to -50 ° C for two hours. 55 ml of water heated to 95 ° C was added with stirring. The temperature rose to + 5 ° C. After four minutes of stirring (pH 0.2), 22 ml of ammonia water was added over 7 minutes to a pH of 3.8. Stirring was continued for several days while cooling. The precipitated 7-ACA was collected by filtration, washed with 50 ml of methylene chloride, 40 ml of water, 50 ml of methanol and then 50 ml of acetone. The dried solid weighed 2.3 g and was 95.4% 7-ACA.

Example 5

Preparation of Sodium N-Carbethoxycephalosporin C The procedure described in Example 1 was repeated except that instead of a 5.9: 1 molar ratio of isobutyl chloroformate to cephalosporin C, a molar ratio of 7.0: 1 was used. ethyl chloroformate per mole of cephalosporin C to give sodium N-carbethoxycephalosporin C.

Example 6 12.0 g of sodium N-carbethoxycephalosporin C, prepared as in Example 5, 45 ml of methylene chloride, 3.47 ml of triethylamine and 7.0 ml of N, N-dimethyl-aniline were added to a 500 ml flask. The slurry was stirred and 4.75 ml of dichlorodimethylsilane was added dropwise at 25-28 ° C. The reaction was held at ca. 25 ° C for 45 minutes. The reaction was cooled abruptly to -60 ° C and 10.8 g of PCI (0.052 mol) in 100 ml of methylene chloride was added at such a rate that the temperature was kept below -40 ° C. Then, 11.7 ml of Ν, Ν-dimethylaniline was added, keeping the temperature at -40 ° C. The reaction was held at -40 ° C for two hours. The reaction was cooled to -73 ° C and 60 ml of methanol containing 2.36 ml of Ν, Ν-dimethylaniline at -78 ° C was added in a rapid stream to the reaction. The temperature rose to -43 ° C, the reaction cooled to -50 ° C and kept at -50 ° C for two hours. 45 ml of water at + 15 ° C + 65 ° C was added to the reaction and the reaction was heated to + 5 ° C and stirred for four minutes. The pH was about 0. 10 ml of concentrated ammonia water was added dropwise over approx. 6 minutes (pH = 1.6). The temperature was maintained at 0 to + 5 ° C with an ice bath. 5 g of ammonium carbonate in 10 ml of water were added to the hydrolysis mixture (pH = 3.0). The pH was then adjusted to 3.8 with 3.0 ml of ammonia water. The crystallization mixture was stirred for two hours in an ice bath and kept in ice for 16 hours. The crystals were filtered off, washed with methylene chloride, 20 ml of water, 50 ml of methanol and acetone. The crystals were dried. 3.72 g of yield = 58.2%.

Example 7

Preparation of N- (Ν'-butylcarbomoyl) cephalosporin C

H OH s.

ho2c - C - (ch2) 3 - C - N _ NH I 0 C - 0 - "\ J-C, 12 - 0 - C - Cllj

NH 0 T

- CO2Na

Cch2), 3 ch3

Two thousand hundreds of liters of culture medium containing cephalosporin C were mixed with 108 kg of filter aid and 300 ml of silicon foam and then filtered at a pH of 6.9 at 10 ° C.

To the filtered medium was added sufficient oxalic acid to obtain a pH of 3.1. After this addition, the pH was adjusted to 2 by the addition of 30% sulfuric acid. 54 kg of fresh filtration aid was added and the mixture was filtered. The filtrate thus obtained was extracted ½ volume of methyl isobutyl ketone (MIBK) at a pH of 2 and then separated. The MIBK phase was discarded.

A quarter volume of acetone was added to the extracted medium and the pH was adjusted to 7.85 with a solution of sodium hydroxide, n-butyl isocyanate (2 kg / 1000 l medium) was added slowly with stirring (a molar ratio of about 6.1 mole of n-butyl isocyanate per mole of 16 cephalosporin C).

The pH was kept constant at 7.8 to 8.0 by the addition of 15% sodium hydroxide, and the temperature was kept in the range 0 to 10 ° C during addition. Stirring was continued until the pH remained constant without further addition of sodium hydroxide, for a period of approx. two hours.

The pH was adjusted to 2 by the addition of 30% sulfuric acid and the acylated medium was extracted with 3/4 volume of n-butanol. The butanol phase was washed with water and then concentrated to ca. half of the initial volume in 36 ° C in vacuo. The water content of the concentrate was negligible.

The concentrate was cooled and a solution of sodium ethyl hexanoate in n-butanol was added to a pH of 4.8. The sodium salt of N, Ν'-butyl-carbamoylcephalosporin C precipitated and collected by filtration. The precipitate was washed with butanol, suspended in petroleum ether, washed with acetone, filtered and dried in a vacuum oven at 40 - 60 ° C to give the product. Examination of the remaining medium showed the presence of less than 15% cephalosporin C activity. The product was sufficiently pure for subsequent preparation of 7-ACA. It appeared as the di-acid.

For C for forH O OO SS-1 ^O: C 47.36; H 6 06; N, 10.54; H2 O 3.38.

Found: C 47.85- H 6.52 * N 10.54- H2 O 3.48.

Example 8 13.4 g of sodium N- (Ν'-butylcarbamoyl) cephalosporin C prepared as in Example 7, 45 ml of methylene chloride, 1.0 ml of dimethylaniline and 3.67 triethylamine were mixed together, 5.0 ml of dichlorodimethylsilane was added with stirring. a temperature of 25 to 28oc. The solution was stirred for 30 minutes. The solution was then cooled to -60 ° C and 11.5 g of phosphorus pentachloride dissolved in 100 ml of methylene chloride was added while maintaining the temperature of the reaction below -40 ° C. An additional 12.4 ml of Ν, Ν-dimethylaniline was added in 10 ml of methylene chloride. The temperature was kept below -40 ° C for two hours, then abruptly cooled to -73 ° C, and a mixture of 60 ml of methanol and 2.5 ml of dimethylaniline cooled to -78 ° C was added slowly. The temperature rose to -47 ° C. The mixture was stirred and cooled again to -50 ° C. After two hours, 55 ml of water was added, heated to + 95 ° C. The temperature rose to + 45 ° C. The mixture was cooled in an ice bath and stirred for four minutes. The pH was less than 0.1. 21.5 ml of ammonia water was added over 8 minutes to a pH of 3.8. The mixture was stirred for several hours and then filtered. The precipitate was collected, washed with 25 ml of methylene chloride, then 25 ml of water, then 50 ml of methanol and finally with 50 ml of acetone. The solid was dried to give 4.05 g of 93.7% 7-ACA.

Example 9

Preparation of Sodium N- (N'-phenylcarbamoyl) -cephalosporin C The procedure of Example 7 was repeated, using a molar ratio of 7: 1 instead of a 6.1: 1 molar ratio of n-butyl isocyanate to cephalosporin C. phenyl isocyanate and cephalosporin C. A product was found which was satisfactory for cleavage to 7-ACA. Examination of the residual medium after extraction showed the presence of less than 15% cephalosporin C activity. It was investigated as the diacid.

Analysis calculated for C 23 H 26 N 4 ° 9 S: C 51.68 - H 4.90; N, 10.48; S, 6.00. Found: C, 51.63; H, 5.27; N, 10.62; S 6.14.

Example 10 13.9 g of sodium N- (N'-phenylcarbamoyl) cephalosporin C, prepared as in Example 9, 45 ml of methylene chloride, 1 ml of dimethylaniline and 3.67 ml of triethylamine were mixed together. 5.5 ml of dichlorodimethylsilane was added with stirring at a temperature of 25 to 28 ° C. The slurry was stirred for 75 minutes, then cooled to -60 ° C and 12.0 g of PCI, in 100 ml of methylene chloride was added. An additional 11.8 ml of dimethylaniline was added in 10 ml of methylene chloride. The temperature was kept at -40 ° C for two hours. The solution was cooled to -75 ° C and a solution of 60 ml of methanol and 2.5 ml of dimethylaniline cooled to -78 ° C was added. The temperature rose to -52 ° C. The temperature was kept in the range -45 ° C to -50 ° C for two hours. 50 ml of water heated to 95 ° C was added with stirring. The temperature rose to + 5 ° C. After four minutes of stirring (pH 0.0), 22 ml of ammonia water was added over a period of 8 minutes to a pH of 3.7. The slurry was stirred for several days while cooling.

The precipitated 7-ACA was collected by filtration, washed with 50 ml of methylene chloride, 40 ml of water, 50 ml of methanol and then with 50 ml of acetone.

Claims (7)

143031 A process for the preparation of 7-aminocephalosporanoic acid by in situ preparation and recovery of a derivative of cephalosporin C and subsequent cleavage thereof, characterized by adding an acylating agent in the form of an isocyanate of the formula R - N = C = 0 or a halogen formate of formula 0 IV X - C - O - R where R represents alkyl of 1-10 carbon atoms or a group of formula wherein n is an integer of 1-6 when B in the formula III below is -OR, and from 0 to 6 when B is -NHR and R 1 and R 2 are the same or different and each represents H, Cl, Br, F, NO 2, alkyl containing 1-10 carbon atoms or alkoxy containing 1-10 carbon atoms, and X represents chlorine, bromine or iodine to an acid-incubated culture medium containing cephalosporin C at a ratio of at least two moles of acylating agent per mole of cephalosporin C at a pH above 7 at a temperature below 40 ° C to form a derivative of cephalosporin C with the general formula: ig 163031 Η O? s M02C - C - (CH2) 3 - c - N - S wherein M represents hydrogen or a metal or amine cation and B represents a group of the formula -NHR or -OR, R having the meaning given above that the derivative of cephalosporin C of formula (III) is recovered from the culture medium and mixed with a silyl compound of formula R \ R R4 XV \ NH ΛΝH \ ^ r4 ^ \ Λ51 ^ 41 H 'or R5 t R6 - Si - X p £ . n wherein R, R and Ry represent hydrogen, halogen, (lower) alkyl, halogeno (lower) alkyl or phenyl, at least one of the groups R, R ° and R 4 being different from halogen and hydrogen, R (lower) alkyl, m is 1 or 2, and X represents halogen or 1 -R 8 "NCT goq where R represents hydrogen or (lower) alkyl, and R represents hydrogen, (lower) alkyl or the group R 5 f R 6 - Si - under anhydrous conditions in the presence of an acid deactivating tertiary amine in an inert solvent to produce the corresponding silyl ester of compound III, mixing the silyl ester with a halogenating agent at a molar ratio of at least one mole of halogenating agent per mole of silyl ester. in an inert solvent in the presence of an acid deactivating tertiary amine at a temperature below 0 ° C to produce in solution of the corresponding imino halide that the solution of imino halide is mixed with an alcohol at a temperature below 0 ° C to produce in solution of d. a corresponding imino ether and the solution of imino ether under acidic conditions is mixed with water or an alcohol or a mixture of both to give 7-aminocephalosporanoic acid. Process according to claim 1, characterized in that the acylating agent is added to a pre-filtered and acid-incubated culture medium at a ratio of from 2 to 10 moles per ml. mole of cephalosporin C at a pH of 7-9 at a temperature of 0-25 ° C and that the derivative is recovered by extraction with a water-immiscible organic solvent at a pH of 1-3. Process according to claim 2, characterized in that R represents H, the molar ratio of acylating agent to cephalosporin C is from 5: 1 to 8: 1, the temperature is from 0 ° C to 15 ° C and the solvent is methyl isobutyl ketone, ethyl acetate, butanol, chloroform, methylene chloride or dichloroethane. Process according to claims 2-3, characterized in that 2 R represents ethyl, n-propyl, isopropyl, n-butyl or isobutyl, R and R represent H and that approx. 6 moles of acylating agent per mole of cephalosporin C at a pH of approx. 8 at a temperature of from 0 to 5 ° C and that the recovery of the compound of formula III occurs at a pH of approx. 2 using n-butanol when the acylating agent is an isocyanate and of methyl isobutyl ketone when the acylating agent is a halogen formate. Process according to any one of claims 1-4, characterized in that the acylating agent is a chloroformate. Process according to any one of claims 1-4, characterized in that the acylating agent is isobutyl chloroformate. Process according to any one of the preceding claims, characterized in that the ratio of equivalent silylating agent to compound III is 1: 1, that the acid-deactivating tertiary amine in each step is triethylamine, trimethylamine, dimethylaniline, quinoline, lutidine or pyridine. solvent in each step is methylene chloride, dichloroethane, chloroform, tetrachloroethane, nitromethane or