Patent Application
20170298406
The present invention relates to the hemi sulfuric acid salt of
Enzymatic production of semisynthetic β-lactam antibiotics by acylation of the parent amino β-lactam moiety with a side chain acid derivative, such as an amide or an ester, has been widely described in the patent literature e.g. DE 2163792, DE 2621618, EP 339751, EP 473008, U.S. Pat. No. 3,816,253, WO 92/01061, WO 93/12250, WO 96/02663, WO 96/05318, WO 96/23796, WO 97/04086, WO 98/56946, WO 99/20786, WO 2005/00367, WO 2006/069984 and WO 2008/110527. The enzymes used in the art are in most cases penicillin acylases obtained from Escherichia coli and are immobilized on various types of water-insoluble materials (e.g. WO 97/04086).
Due to the sensitive nature of biocatalysts, enzymatic processes usually have strict requirements with regard to the presence of contaminants. Often, unwanted impurities disturb the proper functioning of an enzyme. For this reason, also in the enzymatic production of semisynthetic β-lactam antibiotics by acylation of the parent amino β-lactam moiety with a side chain acid derivative, such as an amide or an ester, the starting materials are preferably in the highest possible purity. The latter is usually achieved by isolating the starting materials, preferably by means of crystallization. For example, for
In order to achieve this,
It is an object of the present invention to provide a derivative of
The term “nucleus” is defined herein as the β-lactam moiety of the semi synthetic β-lactam and may be any penem or cephem, for instance 6-aminopenicillanic acid (6-APA), 7-aminodeacetoxy-cephalosporanic acid (7-ADCA), 7-aminocephalosporanic acid (7-ACA) or 7-amino-3-chloro-3-cephem-4-carboxylate (7-ACCA).
The term “side chain” is defined herein as the moiety which in the semi synthetic β-lactam compound is attached to the 6-amino or 7-amino position in the nucleus as defined herein, i.e.
The term “free side chain” is the un-derivatized form of the side chain, i.e.
The term “side chain ester” is the ester form of the free side chain whereby the carboxyl group of the free side chain is esterified to an alcohol, for instance
The term “hemi sulfuric acid salt of
In a first aspect, the invention provides the hemi sulfuric acid salt of
The (PGMH)2SO4 of the present invention advantageously is a stable solid. The only other known stable inorganic acid salt of
In a second aspect, the invention provides a method for the preparation of (PGMH)2SO4 comprising the steps of:
Preferably, the amount of sulfuric acid is chosen such that the molar amount of sulfuric acid is from 0.4 to 0.6 relative to the molar amount of (PGMH)2SO4. In a preferred embodiment, (PGMH)2SO4 is isolated by separating the aqueous phase in step (a) and crystallizing (PGMH)2SO4 therefrom. Crystallization may be carried out according to methods known to the skilled person, for example by lowering the temperature. It was found that a preferred crystallization temperature is from −5 to 15° C., more preferably from 0 to 10° C.
In one embodiment, it was found that the overall yield can be improved by recycling the aqueous phase remaining after the isolation in step (b) of the above method. Thus, the aqueous mother liquor is added to the mixture of step (a) in a next cycle of the method as described above. Preferably recycling is carried out such that part of the aqueous mother liquor is discarded prior to addition to the mixture of step (a). A suitable small part is from 1 to 50% by volume, preferably from 2 to 25% by volume, more preferably from 3 to 15% by volume As a result of the phase separation it was found that this recycling can be performed without accumulation of impurities.
The method of the second aspect can be carried out with various organic solvents. It was found that preferred solvents are those having a solubility in water of from 0% (w/w) to 25% (w/w) and having a polarity index of from 1 to 5. Preferably said polarity index is from 2 to 3 as this generally leads to the best results. Preferred solvents are butyl acetate, diethyl ether, ethyl acetate, methyl isobutyl ketone and methyl tert-butyl ether.
In a third aspect, the invention provides the use of (PGMH)2SO4 in the preparation of ampicillin, cefaclor or cephalexin comprising contacting said (PGMH)2SO4 with 6-aminopenicillanic acid (6-APA), 7-amino-3-chloro-3-cephem-4-carboxylate (7-ACCA) or 7-aminodeacetoxycephalosporanic acid (7-ADCA), respectively in the presence of a penicillin acylase, preferably an immobilized penicillin acylase. This enzymatic reaction may be carried according to any of the processes known in the art and which have been cited hereinbefore. For instance, the synthesis of ampicillin may be carried out as described in EP 339751 or WO 98/56946. Likewise, the synthesis of cephalexin may be carried out as described in WO 96/23796. The synthesis of cefaclor may be carried out as has been described in WO 2006/069984.
After the enzymatic coupling, the semi synthetic beta-lactam antibiotic can be recovered using known methods. For instance, the enzyme reactor may be discharged through the bottom sieve using upwards stirring. The resulting semi synthetic beta-lactam antibiotic suspension may then be filtered through a glass filter.
Due to the low amount of free side chain present after the enzymatic coupling reaction, crystallization of the final semi synthetic beta-lactam antibiotic may be carried out at high concentrations of the beta-lactam antibiotic which results in high yields.
In another embodiment, the third aspect of the invention provides the use of the hemi sulfuric acid salt of
A sample was loaded onto a closed sample holder with inner knife (to minimize background scattering) and cavity (diameter 2 cm). The loading was carried out in a fume hood without grinding, in order to minimize dust formation during the sample preparation. Samples were analyzed on an X-ray powder diffractometer D2 Phaser from Bruker. It uses a LynxEye detector with 1° opening angle, a 0.1 mm receiving slit and a nickel filter. The diffraction angle 2∂ ranges from 2° to 60°, with step (in 2θ)˜0.008° and the count time 4 s/step. The sample rotates at 15 rpm during the measurement (for good statistics) and the data are approximately background subtracted.
An aqueous solution of
An aqueous solution of
In the preparation of (PGMH)2SO4 as described in Example 2 separation of the organic phase at pH=4.2 is done while (PGMH)2SO4 is supersaturated. At some point in time, crystallization may start before the organic layer is separated from the aqueous phase. In order to design a process that will avoid crystallization of (PGMH)2SO4 in the presence of organic solvent, and controlled crystallization after separation of the organic phase, solubility of (PGMH)2SO4 as a function of temperature was investigated. The hemi sulfuric acid salt of
The solubility at 20° C. should allow phase separation after mixing
7-Aminodeacetoxycephalosporanic acid (7-ADCA, 55.4 g) was suspended in water (237 mL) and the temperature was controlled at 20° C. The mixture was stirred for 5 min while maintaining the pH at 7.0 by the addition of an aqueous solution of ammonia (25%). Immobilized enzyme (comprising mutant 1 as described in U.S. Pat. No. 8,541,199; 18.7 g) was added together with water (25 mL). Next, solid (PGMH)2SO4 (61.5 g) was dosed at a constant rate in 200 min. whilst the pH was maintained at 7.0 by the addition of an aqueous solution of ammonia (25%) or with an aqueous solution of sulfuric acid (30%) once all (PGMH)2SO4 was added. After 230 min., the pH was adjusted to 5.8 by addition of an aqueous solution of sulfuric acid (30%). During the course of the reaction samples were taken and analyzed by HPLC with the results as outlined in Table 2.
For comparative reasons the above cephalexin protocol was repeated however using PGM solution (as obtained in by Example 8 of U.S. Pat. No. 8,541,199; 100.7 g; assay PGM: 44%) instead of solid (PGMH)2SO4. In addition the initial suspension of 7-ADCA was in 187 mL of water instead of 237 mL During the course of the reaction samples were taken and analyzed by HPLC with the results as outlined in Table 3.
Inspection of Tables 2 and 3 revealed that the use of solid (PGMH)2SO4 resulted in significantly better results over the use of PGM in solution, in terms of maximum cephalexin formation, maximum conversion and overall S/H ratio.
| Number | Date | Country | Kind |
|---|---|---|---|
| 14185735.9 | Sep 2014 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/071324 | 9/17/2015 | WO | 00 |
