AU2303701A - Novel esters and their use in a process for producing antibacterial beta-lactams - Google Patents

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: Bristol-Myers Squibb Company Actual Inventor(s): John J Usher, Guna Romancik Address for Service: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: NOVEL ESTERS AND THEIR USE IN A PROCESS FOR PRODUCING ANTIBACTERIAL BETA-

LACTAMS

Our Ref: 637347 POF Code: 140109/140109 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1- NOVEL ESTERS AND THEIR USE IN A PROCESS FOR PRODUCING ANTIBACTERIAL p-LACTAMS The present application is a divisional application of Australian Patent Application No. 37264/97, (hereinafter referred to as the "parent" application) the entire contents of which are herein incorporated by reference.

The present invention is directed to novel esters. These esters are useful in a process for the production of antibacterial p-lactams, namely penicillins and cephalosporins, in the presence of the enzyme, acylase.

Japanese Patent Application Publication Nos. 47-25388, 47-29588, 48- 26985, 48-35090, 48-99393, 49-14687, 49-36890, 49-48892, 49-75787, 49- 134893 and 52-110896 teach processes for preparing penicillins or cephalosporins by reacting a methyl or ethyl ester of the acyl moiety to be introduced, with 6-aminopenicillanic acid or 7-aminocephalosporanic acid or derivatives thereof. The acyl source in these references is a lower alkyl ester and especially a methyl ester. Eiji Kondo, et al., U.S. Patent No. 4,340,672, issued July 20, 1982, discloses a process for preparing antibacterial p-lactams, 20 that is penicillins and cephalosporins, by the action of an acylase on a penicillin or cephalosporin nucleus amine and an ester(1) of the following formula as the acyl source

RCOO(CH

2 CHO)nY x (I) wherein RCO is an acyl group of penicillin or cephalosporin side chains; X is a hydrogen atom, lower alkyl group or hydroxy lower alkyl group; Y is a hydrogen atom or a lower alkyl group; and n is an integer from 1 to 20. The foregoing process uses the (poly)ethyleneglycol ester as the acyl source which is freely miscible with water as compared to known acyl sources, such as methyl esters, which have low solubility.

JMN W:\SPECdiv727543.doc 2a WO 92/01061, assigned to Novo Nordisk and published January 23, 1992, relates to a process for the preparation of p-lactam derivatives by enzymatic acylation of the parent amino p-lactam with amides as acylating agents.

The above discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia before the priority date of each claim of this application.

The present invention provides the ester R-COO-CH 2

-CH

2 -OH wherein RCO is D-phenylglycyl or 4-hydroxy-D-phenylglycl. These esters are novel and important reactants in a process described in the parent application because they provide yields of over 90% of the final products. These esters are prepared by known methods.

The novel process described in the parent application is for preparing S* 20 antibacterial p-lactams, that is penicillins and cephalosporins, by the action of an acylase on a penicillin or cephalosporin nucleus amine and an ester having the formula (II) as the acyl source

RCOOCH-R'

R" (II wherein RCO is a penicillin or cephalosporin side chain acyl group; R' is H or

CH

2 X or CHXY; R" is H or CH 2 Y or CHXY and X and Y each are independently hydrogen, hydroxy, lower alkyl or hydroxy-lower alkyl.

JMN W:\SPECMiv727543.doc 3 As used in the specification, unless otherwise indicated explicitly or by context, the acyl group represented by RCO is an acyl of natural or synthetic, penicillins or cephalosporins. The lower alkyl includes alkyl of 1 to 4 carbon atoms.

Throughout the description and claims of this specification, the word "comprise" and variations of the word, such as "comprising" and "comprises", is not intended to exclude other additives, components, integers or steps.

In this process p-lactam antibacterials are produced by reacting an ester of the formula (II) with aminoazetidinone carboxylic acid of the formula (III) in the presence of acylase to produce the p-lactam antibacterial of the formula (IV) acylase RCOOCH-R' NH 2 -Q RCONH-Q HO-CH-R'

I

R" R" wherein RCO is straight, branched, cyclic or partially cyclic lower alkanoyl or lower alkenoyl; monocyclic lower aralkanoyl, monocyclic aryloxylower alkanoyl, N, or S)-heterocyclic-lower alkanoyl, N, or S)-heterocyclic thio-lower alkanoyl, cyanoacetyl, cyanomethyl-thioacetyl, monocyclic arylglycyl, monocyclic cycloalkenylglycyl, monocyclicarylglycolyl, N-acyl-arlglycyl, monocyclicarylmalonyl or arylsulfoalkanoyl, all above optionally having lower alkyl, aminomethyl, halogen, hydroxy, lower alkanoyloxy or lower alkoxy as a substituent, and preferably containing 1 to 15 carbon atoms; NH 2 -Q is an amino source and the substituents R' and R" are as defined above.

In this process the preferred RCO groups are D-phenylglycyl and 4hydroxy-D-phenylglycyl which are well known as side chains of antibiotics such as cephalexin and amoxicillin.

JMN W:\SPECldiv727543.doc 3a The amino source NH 2 -Q refers to the substituent on the 7-amino group or 6-amino group of known cephalosporin or penicillin antibiotics, Q having the formula (VI)

S

OR

oyeN

CO

2 H 0

C

0 2

H

(VI)

wherein Z is hydrogen, halogen, lower alkyl of 1-3 carbon atoms, haloalkyl of 1- 3 carbon atoms, C2-4 alkenyl, a nucleophilic group or lower alkyl of 1-3 carbon atoms substituted by a nucleophilic group. The halogen atom is preferably chlorine, bromine or iodine and preferred representative nucleophilic groups are disclosed in Japanese Patent Application Publication No. 49-81381.

SThe enzyme acylase used in this process can be of plant, animal, fungal or bacterial origin or obtained by recombinant methods. The bacterial or fungal 15 acylases are especially important as far as production, efficiency, cost and stability are concerned.

Representative bacteria or fungi for the acylase source include strains of microorganisms belonging to, for example, genera Acetobacter, 20 Achromobacter, Aeromonas, Alkaligenes, Arthrobacter, Brevibacterium, Beneckea, Bacillus, Corynebacterium, Escherichia, Flavobacterium, Gluconobacter, Kluyvera, Microbacterium, Micrococcus, Nocardia, Proteus, Pseudomonas, Rhodopseudomonas, Spirillum, Staphylococcus, Xanthomonas, Aphanocladium or Cephalosporium, or natural or artificial mutants or variants of them capable of producing acylase for the reaction of this invention. Such strains include those described in, for example, Advances in Applied Microbiology, Volume 20, page 217 (1976), or natural or artificial mutants of JMN W:\SPECdiv727543.doc 4 them available for the reaction of this invention. An especially useful enzyme is penicillin G amidase which can be obtained from Escherichia coli by methods which are well known in the art. It can also be obtained by use of recombinant E. Coli containing the penicillin G amidase gene with a tac promoter by methods which are well known in the art. This method is preferred since it makes available large quantities of the enzyme suitable for the manufacturing process.

The aminoazetidinone carboxylic acid of formula (III) can be used in this process as water soluble alkali metal salts, such as sodium, lithium and potassium, or as an ester, such as methanesulfonylethyl ester or acetonyl ester.

The aminoazetidinones of formula (III) and its salts or esters are known compounds and can be prepared by known methods.

In the parent application it is disclosed that the esters of formula (II) can be prepared by known methods, that is, by reaction of an acid RCOOH with a diol or triol or polyol of the formula (V)

HO-CH-R'

IR" (V) wherein RCO, R' and R" are as defined above. The esterification reaction can be by dehydration under acid catalyzed conditions or by means of acid halide or by ester exchange reactions. The RCOOH and the diol, triol or polyol are .i known compounds or can be obtained by methods which are well known in the art.

The esters of this invention are particularly useful in the process described in the parent application.

Thus, a preferred embodiment of the invention described in the parent application is a process for preparing antibacterial p-lactams, that is, cefprozil, cefadroxil and amoxicillin by the action of penicillin G amidase on penicillin or cephalosporin amines of the following formula (VII) JMN W:\SPECMdlv727543.doc

H

2 N

S

H2N Z OR H 2

N

COOH 0 COOH (VII) 6-APA wherein Z is methyl (in 7-ADCA) or I-propenyl (in 7-PACA, the cefprozil nucleus) group and an ester of the formula (VIII)

R-COO-CH

2

-CH

2 -OH (VIII) wherein RCO is 4-hydroxy-D-phenylglycyl. The penicillin or cephalosporin amines of the formula (VII) are known compounds and can be obtained by methods well known in the art.

The ester of formula (VIII) can be obtained by reacting RCOOH wherein RCO is defined as above with ethylene glycol. The compound RCOOH and ethylene glycol are commercially available.

9 The process described in the parent application is carried out by preparing a solution containing ester, cephalosporin or penicillin amine and the enzyme without a buffer at room temperature. This solution is prepared by 20 dissolving the ester in water and adding ammonium hydroxide until a pH of is reached. Then the penicillin or cephalosporin amine is added to the ester solution and the pH again adjusted to 7.5 with ammonium hydroxide. The mixture is then cooled to 5-150C and the solid enzyme is added to it. During this time, the pH falls about 0.6 units and is not maintained at 7.5 The reaction mixture is then analyzed by high pressure liquid chromatography, for example on a C18 reversed phase column, 5 cm X 4.6 mm, 5im spherosorb ODS2. The final product is obtained in a yield of 90-99%.

JMN W:\SPECMdv727543.doc The process described in the parent application gives the final antibacterial p-lactam in the usual yield of over 90% and sometimes over and occasionally over 99%. The yield obtained by simple alkyl esters, such as methyl are usually in the range of 70 to 90%. Because of the high yield of the final antibiotic obtained by the process, the process is very useful for the manufacture of penicillin or cephalosporin antibiotics.

In this process a typical reaction mixture contains 5-35% of the acyl source (VIII) (preferably 8-12%) and 2-20% of the amine source (VII) (preferably The enzyme can be present in a soluble or insoluble form, but preferably the enzyme is present in the form of an insoluble immobilized preparation. This preparation has advantages, such as improved stability of the enzyme and also relative ease of removal of immobilized enzyme from reaction mixtures as a first step in the isolation of the antibiotic.

o *o JMN W:\SPECMiv727543.doc GD0020A -6- The invention is illustrated but in no way limited by the following Examples: Example 1 Synthesis of cefprozil from (VII) using immobilized recombinant penicillin G amidase as the enzyme and hydroxyethyl ester of 4-hydroxy-D-ohenylglycine prepared by acid catalyzed reaction as the acyl source A mixture of 4-hydroxy-D-phenylglycine (10 ethylene glycol (15 ml) and concentrated sulphuric acid (5 ml) was stirred for 18 hours at 55'C under anhydrous conditions. The solution was cooled, and then ice (10 g) was added to it, and the pH was adjusted to 1.0 with 10 N-NH 4 OH (4.5 ml) giving 40 ml of solution of hydroxyethyl ester.

The enzyme mixture of 20 ml containing 10% ester, 4% (VII), and 8% enzyme (equivalent to 32 IU/ml of enzyme) was made up without buffer as follows: The above prepared ester solution (6.9 ml) was mixed with water (2 ml) and adjusted 20 to pH 7.5 with 10 N-NH 4 OH. Then the compound (VII) (0.8 g) was added to it and the pH adjusted to 7.5 with 1 N-NH 4 OH and the volume to 18.4 ml. Then the mixture was cooled to 5-15'C and solid enzyme (1.6 g; 640 IU) was added to it. The pH was not maintained at 7.5 and fell about 0.6 units during the reaction. The reaction mixture was analyzed by HPLC on a C18 Reverse Phase column 5 cm X 4.6 mm, spherosorb ODS2. The mobile phase was 10% acetonitrile/0.3% H 3

PO

4 2 ml/minute with 215 nm detection. The isomers of cefprozil appeared at 2.9 minutes (cis) and at 5.1 minutes (trans). The final product was obtained with a maximum yield of 92-96%. The whole experiment was completed in 25-50 minutes.

*ooo o GD0020A .7- Example 2 Synthesis of cefprozil from (VII) using immobilized recombinant penicillin G amidase as the enzyme and purified hydroxyethyl ester of 4-hydroxy-D-phenylglycine as the acyl source The purified ester was prepared by the reaction of the Dane salt of 4-hydroxy-Dphenylglycine with bromoethanol and was obtained as a pure crystalline hydrochloride salt.

The reaction mixture of 20 ml containing 12.5% ester, 4% (VII), and 8% enzyme (equivalent to 24 IU/ml of enzyme) was prepared as follows: The purified ester (2.5 prepared as above, was mixed with water (9 ml) and adjusted to pH 8.0 with concentrated NH 4 OH to give a solution. The compound (VII) (0.8 g) was added to the solution and the pH of the solution adjusted to 6.76 with 2M-

H

2

SO

4 and the volume to 18.4 ml. This solution was cooled to 15'C and then solid enzyme (1.6 g; 480 IU) was added to it. The pH was not maintained and fell about 0.6 units during the reaction. The final product was obtained in a maximum yield of 99%.

20 The area percent of unreacted (VII) fell to The experiment was completed in twenty-five minutes.

Example 3 Synthesis of cefadroxil from 7-ADCA using Boehringer penicillin G amidase as the enzyme and hydroxyethyl ester of 4-hydroxy-D-phenylglycine prepared by acid catalyzed reaction as the acyl source The ester was prepared as in Example 1. The experiment was repeated as in Example 1 but at 15'C and using 1.6 g of the Boehringer enzyme. The reaction mixture was analyzed by HPLC on a Merck column, 250-4, LiChrosorb RP-18 (10 im), with acetonitrile/1% NH 4

H

2

PO

4 as mobile phase run at 1.3 ml/minute with 280nm detection. The product was obtained with a maximum yield of The experiment was completed in minutes.

G D0020A -8- Example 4 Synthesis of amoxicillin from 6-APA using Boehringer penicillin G amidase as the enzyme and hydroxyethyl ester of 4-hydroxy-D-phenylglycine Drepared by acid catalyzed reaction as the acyl source A mixture of volume 20 ml containing 12% ester, 3% 6-APA, and 8% enzyme was prepared as follows: A solution of the ester (prepared as in Example 1, 8.3 ml) was mixed with water (2 ml) and adjusted to pH 7.5 with 10 N-NH 4 OH. Then the compound 6-APA (0.6 g) was added to the solution and the pH adjusted to -7.0 with 1N ammonium hydroxide to a volume to 18.4 ml. Then the solution was cooled to 20'C and Boehringer enzyme (1.6 g) was added to it. This solution was analyzed by HPLC on a C18 Reverse Phase column 5cm X 4.6 mm, 5 pm spherosorb ODS 2. The mobile phase was acetonitrile/0.025M NaH 2

PO

4 to pH 3.5 with H 3

PO

4 run 1 ml/minute with 215 nm detection. The final product was obtained in a yield of 90-95% in 160 minutes.

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