CA1122973A - Cephalosporin antibiotics - Google Patents
Cephalosporin antibioticsInfo
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- CA1122973A CA1122973A CA328,415A CA328415A CA1122973A CA 1122973 A CA1122973 A CA 1122973A CA 328415 A CA328415 A CA 328415A CA 1122973 A CA1122973 A CA 1122973A
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Abstract
ABSTRACT OF THE DISCLOSURE
Cephalosporin antibiotics of general formula:
(I) (wherein Ra and Rb, which may be the same or different, each represent a C1-4 alkyl group or Ra and Rb together with the carbon atom to which they are attached form a C3-7 cycloalkylidene group, and Y represents a C-linked 5- or 6-membered heterocyclic ring containing at least one nitrogen atom, which ring may also contain one or more sulphur atoms and/or may be substituted by a C1-4 alkyl group) exhibit broad spectrum antibiotic activity, the activity being unusually high against gram-negative organisms such as strains of Pseudomonas organisms.
Also described are compositions containing the antibiotics of the invention and processes for the preparation of the antibiotics.
Cephalosporin antibiotics of general formula:
(I) (wherein Ra and Rb, which may be the same or different, each represent a C1-4 alkyl group or Ra and Rb together with the carbon atom to which they are attached form a C3-7 cycloalkylidene group, and Y represents a C-linked 5- or 6-membered heterocyclic ring containing at least one nitrogen atom, which ring may also contain one or more sulphur atoms and/or may be substituted by a C1-4 alkyl group) exhibit broad spectrum antibiotic activity, the activity being unusually high against gram-negative organisms such as strains of Pseudomonas organisms.
Also described are compositions containing the antibiotics of the invention and processes for the preparation of the antibiotics.
Description
~2~?73 This invention is concerned with cephalosporin compounds possessing valuable antibiotic properties.
The cephalosporin compounds in this specifica-tion are named with reference to "cepham" after 5 J. Amer Chem. Soc , 1962, 84, 3400, the term "cephem"
referring to the basic cepham structure with one double bond Cephalosporin antibiotics are widely used in the treatment of diseases caused by pathogenic bacteria in 10 human beings and animals, and are especially useful in the treatment of diseases caused by bacteria which are resistant to other antibiotics such as penicillin compounds, and in the treatment of penicillin-sensitive patients. In many instances it is desirable to employ a 15 cephalosporin antibiotic which exhibits activity against both gram-positive and gram-negative microorganisms, and a significant amount of research has been directed to the development of various types of broad spectrum cephalo-sporin antibiotics.
Thus, for example, in our British Patent Specifica-tion No. 1,399,086, we describe a novel class of cephalo-~p~rin antibiotics containing a 7~ -etherified oximino)-acylamido group, the oximino group having the syn $
l~ZZ~'73 configuration. This class of antibiotic compo~mds is characterised by high antibacterial activity against a range of gram-positive and gram-negative organisms coupled with particularly high stability to ~-lactamases produced by various gram-negative organisms.
The discovery of this class of compounds has stimulated further research in the same area in attempts to find compounds which have improved properties, for example against particular classes of organisms especially gram-negative organisms.
In our British Patent Specification No. 1,496,757, we describe cephalosporin antibiotics containing a 7~-acylamido group of the formula R.C.CO.NH- A
0. tCH2) C (CH2) COOH (A) RB
(wherein R is a thienyl or furyl group; R and RB may vary widely and may,for example,be Cl 4 alkyl groups or together with the carbon atom to which they are attached form a C3 7 cycloalkylidene group, and m and n are each 0 or 1 such that the sum of m and n is 0 or l), the compounds being syn isomers or mixtures of syn and anti isomers containing at least 90% of the syn isomer. The 3-position of the cephalosporin molecule may be unsubstituted or may contain one of a wide variety of possible substituents. These compounds have been found to have particularly good activity against gram-negative organisms.
l~Z297:~
Other compounds of similar structure have been developed from these compounds in further attempts to find antibiotics having improved broad spectrum anti-biotic activity and/or high activity against gram-5 negative organisms. Such developments have involvedvariations in not only the 7~-acylamido group in the above formula but also the introduction of particular groups in the 3-position of the cephalosporin molecule.
Thus, for example, in Belgian Patent Specification 10 No. 852,427, there are described cephalosporin antibiotic compo~mds falling within the general scope of our British Patent Specification No. 1,399,086, and wherein the group R in formula (A) above may be replaced by a variety of different organic groups, including 2-aminothiazoI-4-yl, and the oxygen atom in the oxyimino group is attached to an aliphatic hydrocarbon group which may itself be substituted by, for example, carboxy. In such compounds, the substituent at the 3:position may vary widely and ~ay be inter alia an optionally substituted hetero~yclic-thiomethyl ~roup.
20 Many examples of such groups are given in the specifica-tion including those in which the heterocyclic moiety of the group is a 3- to 8- membered heterocyclic ring containing 1 to 4 nitrogen atoms, e.g. an imidazolyl, pyrazolyl, pyridyl, pyrimidyl or tetrazolyl group which may be substituted, e.g. a 1-methyl-lH-tetrazol-5-yl group.
Furthermore, Belgian Patent Specification No.
836,813 describes cephalosporin compounds wherein the group R in formula (A) above may be replaced by, for example, 2-aminothiazol-4-yl, and the oxyimino group llZ~973 is a hydroxyimino or blocked hydroxyimino group, e.g. a methoxyimino group. In such compounds, the 3-position of the cephalosporin molecule is substituted by a methyl group which may itself be optionally substituted by any of a large number of residues of nucleophilic compounds therein described. Examples of such residues include the mercapto group ~hich may be attached to a 5- or 6-membered heterocyclic ring which may contain 1 to 4 - heteroatoms selected from oxygen, sulphur and nitrogen, e.g. pyridyl, pyrimidyl, pyrazolyl, or irnidazolyl, which rings may, if desired, be substituted for example by lower alkyl groups. In the above mentioned Specifica-tion no antibiotic activity is ascribed to such compounds which are only mentioned as intermediates for the preparation of antibiotics descrlbed in that speci-fication.
Belgian Patent Specification No.853,545 describes cephalosporin antibiotics wherein the 7~-acylamido side chain is primarily a 2-(2-aminothiazol-4-yl)
The cephalosporin compounds in this specifica-tion are named with reference to "cepham" after 5 J. Amer Chem. Soc , 1962, 84, 3400, the term "cephem"
referring to the basic cepham structure with one double bond Cephalosporin antibiotics are widely used in the treatment of diseases caused by pathogenic bacteria in 10 human beings and animals, and are especially useful in the treatment of diseases caused by bacteria which are resistant to other antibiotics such as penicillin compounds, and in the treatment of penicillin-sensitive patients. In many instances it is desirable to employ a 15 cephalosporin antibiotic which exhibits activity against both gram-positive and gram-negative microorganisms, and a significant amount of research has been directed to the development of various types of broad spectrum cephalo-sporin antibiotics.
Thus, for example, in our British Patent Specifica-tion No. 1,399,086, we describe a novel class of cephalo-~p~rin antibiotics containing a 7~ -etherified oximino)-acylamido group, the oximino group having the syn $
l~ZZ~'73 configuration. This class of antibiotic compo~mds is characterised by high antibacterial activity against a range of gram-positive and gram-negative organisms coupled with particularly high stability to ~-lactamases produced by various gram-negative organisms.
The discovery of this class of compounds has stimulated further research in the same area in attempts to find compounds which have improved properties, for example against particular classes of organisms especially gram-negative organisms.
In our British Patent Specification No. 1,496,757, we describe cephalosporin antibiotics containing a 7~-acylamido group of the formula R.C.CO.NH- A
0. tCH2) C (CH2) COOH (A) RB
(wherein R is a thienyl or furyl group; R and RB may vary widely and may,for example,be Cl 4 alkyl groups or together with the carbon atom to which they are attached form a C3 7 cycloalkylidene group, and m and n are each 0 or 1 such that the sum of m and n is 0 or l), the compounds being syn isomers or mixtures of syn and anti isomers containing at least 90% of the syn isomer. The 3-position of the cephalosporin molecule may be unsubstituted or may contain one of a wide variety of possible substituents. These compounds have been found to have particularly good activity against gram-negative organisms.
l~Z297:~
Other compounds of similar structure have been developed from these compounds in further attempts to find antibiotics having improved broad spectrum anti-biotic activity and/or high activity against gram-5 negative organisms. Such developments have involvedvariations in not only the 7~-acylamido group in the above formula but also the introduction of particular groups in the 3-position of the cephalosporin molecule.
Thus, for example, in Belgian Patent Specification 10 No. 852,427, there are described cephalosporin antibiotic compo~mds falling within the general scope of our British Patent Specification No. 1,399,086, and wherein the group R in formula (A) above may be replaced by a variety of different organic groups, including 2-aminothiazoI-4-yl, and the oxygen atom in the oxyimino group is attached to an aliphatic hydrocarbon group which may itself be substituted by, for example, carboxy. In such compounds, the substituent at the 3:position may vary widely and ~ay be inter alia an optionally substituted hetero~yclic-thiomethyl ~roup.
20 Many examples of such groups are given in the specifica-tion including those in which the heterocyclic moiety of the group is a 3- to 8- membered heterocyclic ring containing 1 to 4 nitrogen atoms, e.g. an imidazolyl, pyrazolyl, pyridyl, pyrimidyl or tetrazolyl group which may be substituted, e.g. a 1-methyl-lH-tetrazol-5-yl group.
Furthermore, Belgian Patent Specification No.
836,813 describes cephalosporin compounds wherein the group R in formula (A) above may be replaced by, for example, 2-aminothiazol-4-yl, and the oxyimino group llZ~973 is a hydroxyimino or blocked hydroxyimino group, e.g. a methoxyimino group. In such compounds, the 3-position of the cephalosporin molecule is substituted by a methyl group which may itself be optionally substituted by any of a large number of residues of nucleophilic compounds therein described. Examples of such residues include the mercapto group ~hich may be attached to a 5- or 6-membered heterocyclic ring which may contain 1 to 4 - heteroatoms selected from oxygen, sulphur and nitrogen, e.g. pyridyl, pyrimidyl, pyrazolyl, or irnidazolyl, which rings may, if desired, be substituted for example by lower alkyl groups. In the above mentioned Specifica-tion no antibiotic activity is ascribed to such compounds which are only mentioned as intermediates for the preparation of antibiotics descrlbed in that speci-fication.
Belgian Patent Specification No.853,545 describes cephalosporin antibiotics wherein the 7~-acylamido side chain is primarily a 2-(2-aminothiazol-4-yl)
-2-(_y~)-methoxyimino-acetamido group and the substituent in the 3-positio~ is broadly defined in a similar ~a~
to that in the above-mentioned Belgian Patent Specifica-tion No. 836,813. Cornpounds specifically exemplified in the Specification include compounds in which the
to that in the above-mentioned Belgian Patent Specifica-tion No. 836,813. Cornpounds specifically exemplified in the Specification include compounds in which the
3-position is substituted by various heterocyclic-thio methyl radicals including methyltetrazolylthiomethyl radicals.
We have now discovered that by an appropriate selection of a small number of particular groups at the ~q~
7~-position in combination with a heterocyclic-substituted thiomethyl group at the 3-position, cephalosporin compounds having particularly advantageous activity (described in more detail below) against a wide range of commonly encountered pathogenic organisms may be obtained.
The present invention provides cephalosporin antibiotics of the general formula =~L--C r CO ~ NH ~-- H H
N\ ~ ~ 1 !~ ~ (I) O.C.COOH COOH
Rb (wherein Ra and Rb, which may be the same or different, each represent a Cl 4 alkyl group (preferably a straight chain alkyl group, i.e. a methyl, ethyl, n-propyl or n-butyl group and particularly a methyl or ethyl group) or Ra and Rb together with the carbon atom to which they are attached form a C3 7 cycloalkylidene group, preferably a C3 5 cycloalkylidene group;
and Y represents a C-linked tetrazolyl group optionally substituted by a Cl 4 alkyl group) and non-toxic salts and non-toxic metabolically labile esters thereof.
The compounds according to the invention are ~y~
isomers. The sYn isomeric form is defined by the ~ -5-~ .~
:11229173 configuration of the group i ! ' ' .
I 1~
with respcct to the carboxamido group. In this specification the ~y~ configuration is denoted structurally as J ~2 S N
\O . (' . (`0()1~
It will be understood that since the compo~mds accord-ing to the invention are geometric isomers, some admixture with the corresponding anti isomer may occur.
The invention also includes within its scope the solvates (especially the hydrates) of the compounds of formula (I). It also includes within its scope salts of esters of compounds of formula (I).
The compounds according to the present invention may exist in tautomeric forms (for example in respect of the 2-~minothiazolyl group) and it will be understood that such tautomeric forms, e.g. the 2-iminothiazolinyl ~122~73 form, are included within the scope of the invention.
It will also be appreciated that when Ra and Rb in the above formula represent different Cl 4 alkyl groups, the carbon atom to which they are attached will comprise a centre of asymmetry. Such compounds are diastereoisomeric and the present invention embraces individual diastereoisomers of these compounds as well as mixtures thereof.
In formula (I) above, the heterocyclic ring represented by Y may, if desired, be substituted by a Cl 4 alkyl group, e.g.
a methyl group.
The compounds according to the invention exhibit broad spectrum antibiotic activity. Against gram-~1122973 negative organisms the activity is unusually high.This high activity extends to many ~-lactamase-producing gram-negative strains. The compounds also possess high stability to ~-lactamases produced by a range of gram-negative organisms.
Compounds according to the invention have been found to exhibit unusually high activity against strains of Pseudomonas organisms, e.gO strains of Pseudomonas aeruginosa as well as high activity against various members of the Enterobacteriaceae (e.g, strains of Escherichia coli, ~lebsiella pneumoniae, Salmonella typhimurium, S~i&~ sonnei, _ Enterobacter cloacae, Serratia marcescens,Providence species, Proteus mirabilis and especially indole-positive 15 Proteus organisms such as Proteus vulgaris and Proteus _ _ morganii),and strains of Haemophilus in~luenzae.
~12Z97;~
The antibiotic properties of the compounds according to the invention compare very favourably with those of the ami.noglycosides s~lch as am;kac;.n or gentamicin, In particular, thi.s applies to their activity against strains of various Pseudomonas organisms which are not susceptable to the majority of exist-ing commercially available antibiotic compounds.
Unlike the aminoglycosides, cephalospori.n anti.biotics normally exhibi.t low toxicity in man, The use of amino-glyco~sides in human therapy tends to be limited orcompli.caLed by the hightoxici~y c~ these antibiotics.
The cepllalospori.n antib;otics of the present imvelltion thus possess potentially great advantages over the ami.lloglycosi.des~
~on-toxic salt derivatives which may be formed by reaction of either or both of the carboxyl groups present i,n the compounds of general ~orrnula (I) include inorganic base salts such as alkali metal sa]-s (e.g.
sodium and potassium salts) and alkaline earth Inetal salts (e.g. calci.um salts); an-l;no aci,d ~salts (e.g. ]y.sine and arginine sa]ts); organi.c base salts (e.g. ploca;.lle, phenylethyl-benzy]amine, dibenzylethylenecliarnine, ethanolamine, diethanolamine and N-methylglucosamine salts). Other non-toxic salt derivatives include acid addition salts, e.g. formed with hydrochloric, hydrobromic, sulphuric, nitric, phosphoric, formic and trifluoroacetic acids. The salts may also be in the form of resinates formed with, for example, a polystyrene resin or cross-]inked polystyrene divinylbenzene copolymer resin containing amino or quarternary amino 10 groups or sulphonic acid groups, or with à resin containing carboxyl groups, e.g. a polyacrylic acid resin. Soluble base salts (e.g. alkali metal salts such as the sodium salt) of compounds of formula (I)`
may be used in therapeutic applications because of the rapid distribution of such salts in the body upon administration. Where, however, insoluble salts of compounds (I) are desired in a particular application, e.g. for use in depot preparations, such salts may be formed in conventional manner, for example with 20 appropriate organic amines.
These and other salt derivatives such as the salts with toluene-~-sulphonic and methanesulphonic acids may be employed as intermediates in the prepara-tion and/or purification of the present compounds of 25 formula (I), for example in the processes described below, Non-toxic metabolically labile ester derivatives which may be formed by esterification of either or both carboxyl groups in the parent compound of formula (I) ~iZ2~373 include acyloxyalkyl esters, e.g. lower alkanoyloxy-methyl or -ethyl esters such as acetoxy-methyl or -ethyl or pivaloyloxy-methyl esters. In addition to the above ester derivatives, the present invention includes within its scope compounds of formula (I) in the form of other physiologically acceptable equivalents, i.e. physiologically acceptable compounds which, like the meta-bolically labile esters, are converted in vivo into the parent antibiotic compound of formula (I).
:1~22~
Examples of preferred compounds according to the present invention include the ollowing compounds of formula (I) and their non-toxic salts and non-toxic metabolically labile esters, namely:-(6R,7R)-7-[(Z~-2-(2-aminothiazol-4-yl)-2-(2-carboxyprop-2-oxyimino) acetamido~-3~ methyltetrazol-5-ylthiomethyl) ceph-3-em-4-carboxylic acid (6R,7R)-7-~(Z)-2-(2-aminothiazol-4-yl)-2-(1-carboxycyclo-but-l-oxyimino) acetamido~-3~ methyltetrazol-5-ylthio-methyl) ceph-3-em-4-carboxylic acid, Other compounds according to the present invention include for example those wherein the groups R , R and Y in formula (I) are as follows:-:l~Z~ 3 _ . _ . . _ . _ _ . , . . _ .
Ra Rb Y
. __ . . . . __ . _ . _ . . __, ~) ,Alkyl groups ~ . .
~3 ~ C2H5 l.methyl-tetrazol-5-yl-b~ Cycloalkylidene groups __ . __ .
cyclopropylidene l-methyl-tetrazol-5-yl cyc lopentylidene . . . _ . ._ ~lZ2973 The compounds of formula (I) may be used for treating a variety of diseases caused by pathogenic bacteria in human beings and animals, such as respiratory tract infections and urinary tract infections.
According to another embodiment of the invention we provide a process for the preparation of an antibiotic compound of general formula (I) as hereinbefore defined or a non-toxic salt (including internal salt) or non-toxic metabolically labile ester thereof which comprises (A) a~ylating a compound of the formula 1.~ 11 H2 = B
N ~ SY
COORl (II) [wherein Y is as defined above; B is )S or ) S--~ 0 (~-or ~-); R represents hydrogen or a carboxyl blocking group, e.g. the residue of an ester-forming aliphatic or araliphatic alcohol or an ester-forming phenol, silanol or stannanol (the said alcohol, phenol, silanol or stannanol preferably containing 1-20 carbon atoms); and the dotted line bridging the 2-, 3-, and 4-positions indicates that the compound is a ceph-2-em or ceph-3-em compound] or a salt, e.g. an acid addition salt (formed with, for example, a mineral acid such as hydrochloric, hydrobromic, sulphuric, nitric or phosphoric acid or an organic acid such as methanesulphonic or toluene-p-sulphonic acid) or an N-silyl derivative thereof, with an acid of formula ~2~973 S N
C.COOH
Il a N R
\ O.C.COOR (III) Ib (wherein Ra and Rb are as hereinbefore dcfined; R2 rcpresents a carboxyl blockin~ group, e.g. as described for R ; and R is an amino or protected amino group) or with an acylating agent corresponding thereto; (B) reacting a compound of formula S N
\ / -C.~O.~ ~ B ~
N Ra oJ ~ CI~ X
\ o.~.. cooR4a (,ooR4 Rb (IV) (wherein R , Rb, R3, B and thc dotted llne are as dcfined above; R4 and R4a may lndependently rcpresent hydrogen or a carboxyl blocking group; and X is a replaceable residue of a nucleophile, e.g. an acetoxy or dichloroacetoxy group or a halogen atom such as chlorine, bromine or iodine) or a salt thereof with a sulphur nucleophile serving to form a group of formula -CH2SY (wherein Y is as defined above~
at the 3-position; whereafter, if neoessary-and/or desired in 1~229'73 each instance, any of the following reactions, in any appropriate sequence, are carried out:-i) conversion of a Q -isomer into the desired Q -isomer, S ii) reduction of a compound wherein B is >S ? O to form a compound wherein B is >S, iii) conversion of a carboxyl group into a non-toxic salt or non-toxic metabolically labile ester function, and iv) removal of any carbox~ blocking and/or N-protecting groups.
In the above-described process (A), the starting material of formula (II) is preferably a compound wherein B is >S and the dotted line represents a ceph-3-em compound, Acylating agents which may be ernployed in the preparation of compo~mds of forlnula (I) include acid halides, particularly acid chlorides or bromides. Sucll acylating agents may be prepared by reacting an acid (III) or a salt thereof with a halogenating agent e.g.
phosphorus pentachloride, thionyl chloride or oxalyl chloride.
Acylations employing acid halides may be effected in aqueous and non-aqueous reaction media, conveniently at temperatures of from -50 to +50C, preferably -20 to +30C, if desired in the presence of an acid binding agent. Suitable reaction media include aqueous ketones such as aqueous acetone, esters such as ethyl acetate, halogenated hydrocarbons such as methylene chloride, amides such as dimethylacetamide, nitriles such as acetonitrile, or mixtures of two or more such solvents.
Suitable acid binding agents include tertiary amines (e.g. triethylamine or dimethylaniline), inorganic bases (e.g. calcium carbonate or sodi~lm bicarbonate), and oxiranes such as lower 1,2-alkylene oxides (e.g. ethylene oxide or propylene oxide) which bind hydrogen halide liberated in the acylation reaction.
Acids of formula (III) may themselves be used as acylating agents in the preparation of compounds of 1~2~973 1~
formula (I). Acylations employing acids (III) are desirably conducted in the presence of a condensing agent, for example a carbodiimide such as N,N'-dicyclohexyl-carbodiimide or N-ethyl-N'-y-dimethylaminopropylcarbodiimide;
a carbonyl compound such as carbonyldiimidazole; or an isoxazolium salt such as N-ethyl-5-phenylisoxazolium perchlorate.
Acylation may also be effected with other amide-forming derivatives of acids of formula (III) such as, for example, an activated ester, a symmetrical anhydride or a mixed anhydride (e.g. formed with pivalic acid or with a haloformate, such as a lower alkylhaloformate). Mixed anhydrides may also be formed with phosphorus acids (for example phosphoric or phosphorous acids), sulphuric acid or aliphatic or aromatic sulphonic acids (for example toluene-p-sulphonic acid). An activated ester may conveniently be formed in situ using, for example, l-hydroxybenzotriazole in the presence of a condensing agent as set out above. Alternatively, the activated ester may be preformed.
Acylation reactions involving the free acids or their above-mentioned amide-forming derivatives are desirably effected in an anhydrous reaction medium, e.g.
methylene chloride, tetrahydrofuran, dimethylformamide or acetonitrile.
If desired, the above acylation reactions may be carried out in the presence of a catalyst such as 4-dimethylaminopyridine.
The acids of formula (III) and acylating agents corresponding thereto may, if desired, be prepared and employed in the form of their acid addition salts. Thus, for example, acid chlorides may conveniently be emp]oyed li;~Z97j~
as their hydrochloride salts, and acid bromides as their hydrobromide salts.
In process (B) above, the sulphur nucleophile may be used to displace a wide variety of substituents X
from the cephalosporin of formula (IV~. To some extent the facility of the displacement is related to the pKa of the acid HX from which the substituent is derived. Thus, atoms or groups X derived from strong acids tend, in general, to be more easily displaced than atoms or groups derived from weaker acids. The facility of the displacement is also related, to some extent, to the precise character of the sulphur nucleophile. The latter nucleophile may be employed for example in the form of an appropriate thiol or thione.
The displacement of X by the sulphur nucleophile may conveniently be effected by maintaining the reactants in solution or suspension. The reaction is advantageously effected using from 1 to 10 moles of the nucleophile.
Nucleophilic displacement reactions may conveniently be carried out on those compounds of formula (IV) wherein the substituent X is a halogen atom or an acyloxy group, for example as discussed below.
Acylo~ rou~s Compounds of formula (IV) wherein X is an acetoxy 2~ group are convenient starting materials for use in the nucleophilic displacement reaction with the sulphur nucleophile. Alternative starting materials in this class include compounds of formula (IV) in which X is the residue of a 9ubstituted acetic acid e.g. chloroacetic acid, dichloroacetic acid and trifluoroacetic acid.
Displacement reactions on compounds (IV) possessing X substitue~ts of this class, particularly in the case where liZ2973 X is an acetoxy group, may be facilitated by the presence in the reaction medium of iodide or thiocyanate ions.
The substituent X may also be derived from formic acid, a haloformic acid such as chloroformic acid,or a carbamic acid.
When using a compound of formula (IV) in which X represents an acetoxy or substituted acetoxy group, it is generally desirable that the group R4 in formula (IV) should be a hydrogen atom and that B should represent ~S.
In this case, the reaction is advantageously effected in an aqueous medium.
Under aqueous conditions, the pH value of the reaction solution is advantageously maintained in the range 6-g, if necessary by the addition of a base. The base is conveniently an alkali metal or alkaline earth metal hydroxide or bicarbonate such as sodium hydroxide or sodium bicarbonate.
When using compounds of formula (IV) in which X
is an acetoxy group, the reaction is conveniently effected at a ter.~perature of 30C to 110C, preferably 50 to 80C.
- Halo~ens Compounds o~ ~orrnula (IV) in which X is a chlorine, bromine or iodine atom can also be conveniently used as starting materials in the nucleophilic displacement reaction with the sulphur nucelophile. When using compounds of formula (IV) in this class, B may represent ~ S and R4may represent a carboxyl b]ocking group. The reaction is conveniently effected in a non-aqueous medlum which preferably comprises one or more organic solvents, advantageously of a polar nature such as ethers, e.g. dioxan or tetrahydrofuran, esters, e.g.
....
lJ Z2973 ethyl acetate, amides, e.g. formamide and N,N-dimethyl-formamide, and ketones e.g. acetone. Other suitable organic solvents are described in more detail in British Patent Specification No. 1,326,531. The reaction medium shou]d be neither extremely acidic nor extremely basic.
When using compounds of formula (IV) in which X
is a halogen atom as described above, the reaction is conveniently effected at a temperature of -20 to +60, preferably 0 to ~30C.
The react;on is generally effected in the presence of an acid scavenging agent for example a base such as triethylamine or calcium carbonate.
~ZZ9~3 The reacti.on product may be separated from the reaction mixture, which may contain, for example, unchanged cephalosporin starting material and other substances, by a variety of processes including recrystalli.sation, ionophoresis~ column chromatography and use of ion-exchangers (for example by chromatography on ion-exchange resins) or macroreticular resins.
~ -Cephalosporin ester derivatives obtained in accordance with the process of the invention may be converted lnto the corresponding ~ -derivative by, for example, treatment of the ~ -ester with a base, such as pyridine or triethylamine.
A ceph-2-em reaction product may also be oxidised to yield the corresponding ceph-3-em l-oxide, for example by reaction with a peracid, e.g. peracetic or m chloroperbenzoic acid; the resulting sulphoxide may, if desired, subsequently be reduced as described hereinafter to yield the corresponding ceph-3-em sulphide.
Where a compound is obtained in which B is > S ~ 0 this may be converted to the corresponding sulphide by, for example, reduction of the corresponding acyloxysulphonium or alkoxysulphonium salt prepared in situ by reaction with e.g. acetyl chloride in the case of an acetoxysulphonium salt, reduction being effected by, for example, sodium dithionite or by iodide ion as in a solution of potassium iodide in a water-miscible solvent e.g. acetic acid, acetone, tetrahydrofuran, dioxan, dimethylformamide or dimethylacetamide. The reaction may be effected at a temperature of from -20 to +50C.
Metabolically labile ester derivatives of the compounds of formula (I) may be prepared by reacting a compound of formula (I) or a salt or protected derivative thereof with the appropriate esterifying agent such as an acyloxyalkyl halide (e.g. iodide) conveniently in an inert organic solvent such as dimethylformamide or acetone, followed,where necessary9 by removal of any protecting groups.
Base salts of the compound of formula (I) may be formed by reacting an acid of formula (I) with an appropriate base. Thus, for example, sodium or potassium salts may be prepared using the respective 2-ethylhexanoate or hydrogen carbonate salt. Acid addition salts may be prepared by reacting a compound of formula (I) or a metabolically labile ester derivative thereof with the appropriate acid~
Where a compound of formula (I) is obtained as a mixture of isomers, the ~y~ isomer may be obtained by, ~Z~973 2~ -for example, conventional methods such as crystallisation or chromatography.
For use as starting materials for the preparation of compounds of general formula (I) according to the invention, compounds of general formula (III) and acid halides and anhydrides corresponding thereto in their ~y_ isomeric form or in the form of mixtures of the syn isomers and the corresponding anti isomers containing at least 90% of the syn isomer are preferably used.
Acids of formula (III) (provided that R and R
together with the carbon atom to which they are attached do not form a cyclopropylidene group) may be prepared by etherification of a compound of formula ~s~
ooR5 !1 (v) OH
(wherein R is as hereinbefore defined and R represents a carboxyl blocking group), by reaction with a compound of general formula Ra T.c.cooR2 Rb (VI) (wherein R and R and R are as hereinbefore defined and T is halogen such as chloro, bromo or iodo;
sulphate; or sulphonate such as tosylate), followed by removal of the carboxyl blocking group R5~ Separation of isomers may be effected either before or after such ~ ..
ll~Z~73 - 25 ~
etherification. The etherification reaction is generally carried out in the presence of a base, e.g. potassium carbonate or sodium hydride, and is preferably conducted in an organic solvent, for example dimethylsulphoxide, a cyclic ether such as tetrahydrofuran or dioxan, or an N,N-disubstituted amide such as dimethylformamide. Under these conditions the configuration of the oxyimino group is substantially unchanged by the etherification reaction. The reaction should be effected in the presence of a base if an acid addition salt of a compound of formula (V) ,s used.
The base should be used in sufficient quantity to neutralise rapidly the acid in guestion.
Acids of general formula (III) may also be prepared by reaction of a compound of formula S~
~ CO.COOR ~V~I) (wherein R and R are as hereinbefore defined) with a compound of formula lRa 2 H2N.O.C.COOR (VIII) Rb (wherein Ra, Rb and R are as defined above), followed by removal of the carboxyl blocking group R , and where necessary by the separation of syn and anti isomers.
The last mentioned reaction is particularly applicable to the preparation of acids of formula (III) wherein Ra and Rb together with the carbon atom to which they are attached form a cyclopropylidene group. In this case, the relevant compounds of formula (VIII) may be prepared in conventional manner, e.g. by means of the synthesis described in Belgian Patent Specification No.
866,422 for the preparation of t-butyl l-amino-oxycyclo-propane carboxylate.
The acids of formula (III) may be converted to the corresponding acid halides and anhydrides and acid addition salts by conventional methods, for example as described hereinabove.
Where X is a halogen (i.e. chlorine, bromine or iodine) atom in formula (IV), ceph-3-em starting compounds may be prepared in conventional mamler, e.g. by halogenation of a 7~-protected amino-3-methylceph-3-em-4-carboxylic acid ester l~-oxide, removal of the 7~-protecting group, acylation of the resulting 7~-amino compound to form the desired 7~-acylamido group, e.g.
in an analogous manner to process (A) above, followed by reduction of the l~-oxide group later in the sequence.
This is described in British Patent No. 1,326,531. The corresponding ceph-2-em compounds may be prepared by the method of Dutch published Patent Application No.
6,902,013 by reaction of a 3-methylceph-2-em compound with N-bromosuccinimide to yield the corresponding 3-bromomethylceph-2-em-compound.
Where X in formula (IV) is an acetoxy group, such starting materials may be prepared for example by acylation of 7-aminocephalosporanic acid, e.g. in an analogous manner to process (A) above. Compounds of formula (IV) in which X represents other acyloxy groups can be prepared by acylation of the corresponding 3-~122~'73 hydroxymethyl compounds which may be prepared for example by hydrolysis of the appropriate 3-acetoxymethyl compounds, e.g. as described for example in British Patent Specifications Nos. 1,474,519 and 1,531,212.
Compounds of formula (II) may also be prepared in con-ventional manner, e.g. by nucleophilic displacement of a corresponding 3-acyloxymethyl or 3-halomethyl compound with the appropriate nucleophile, e.g. as described in British Patents Nos.1,012,943 and 1,241,657.
A further method for the preparation of the starting - materials of formula (II) comprises deprotecting a corresponding protected 7~-amino compound in conventional manner, e.g.
using PC15 It should be appreciated that in some of the above transformati~ns it may be necessary to protect any sensitive groups in the molecule of the compound in question to avoid undesirable side reactions. For example, during any of the reaction sequences referred to above it may be necessary to protect the NH2 group of the aminothiazolyl moiety, for example by tritylation, acylation (e.g. chloroacetylation), protonation or other conventional method. The protecting group rnay there-after be removed in any convenient way which does not cause breakdown of the desired compound, e.g. in the case of a trityl group by using an optionally halogenated carboxylic acid, e.g. acetic acid, formic acid, chloroacetic acid or trifluoroacetic acid or using a mineral acid, e.g. hydrochloric acid or mixtures of such acids, preferably in the presence of a protic solvent such as water, or, in the case of a chloro-acetyl group, by treatment with thiourea.
Carboxyl blocking groups used in the preparation of compounds of formula (I) or in the preparation of necessary starting materials are desirably groups which llZ~73 may readily be split off at a suitable stage in the reaction sequence, conveniently at the last stage. ~t may, however, be convenient in some instances to employ non-toxic metabolically labile carboxyl blocking groups such as acyloxy-methyl or -ethyl groups (e.g.
acetoxy-methyl or-ethyl or pivaloyloxymethyl) and retain these in the final product to give an appropriate ester derivative of a compound of formula (I), Suitable carboxyl blocking groups are well known in the art, a list of representative blocked carboxyl groups being included in British Patent No. 1,399,086.
Preferred blocked carboxyl groups include aryl lower alkoxycarbonyl groups such as p-methoxybenzyloxycarbonyl, p-nitrobenzyloxycarbonyl and diphenylmethoxycarbonyl;
lower alkoxycarbonyl groups such as t-butoxycarbonyl; and lower haloalkoxycarbonyl groups such as 2,2,2-trichloroethoxycarbonyl. Carboxyl blocking group(s) may subsequently be removed by any of the appropriate methods disclosed in the literature; thus, for example, acid or base catalysed hydrolysis is applicable in many cases, as are enzymically-catalysed hydrolyses.
The antibiotic compounds of the invention may be formulated for administration in any convenient way~ by analogy with other antibiotics and the invention therefore includes within its scope pharmaceutical compositions comprising an antibiotic compound in accordance with the invention adapted for use in human or veterinary medicine.
Such compositions may be presented for use in conventional ~anner ~ith the aid of any necessary pharmaceutical carriers or excipients.
The antibiotic compounds according to the invention 1~229~j3 2g may be formulated for injection and may be presented in unit dose form in ampoules, or in muLti-dose containers, if necessary with an added preservative. The compositions may also take such forms as suspensions, solutions, or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilising and/or dispersing agents. Alternatively the active ingredient may be in powder form for reconstitution with a suitable vehicle, e.g. sterile, pyrogen-free water, before use.
If desired, such powder formulations may contain an appropriate non-toxic base in order to improve the water-solubility of the active ingredient andlor to ensure that when the powder is reconstituted with water, the pH of the resulting aqueous formulation is physiologically acceptable. Alternatively the base may be present in the water with which the powder is reconstituted. The base may be, for example, an inorganic base such as sodium carbonate, sodium bicarbonate or sodium acetate, or an organic base such as lysine or lysine acetate.
The antibiotic compounds may also be formulated as suppositories, e.g~ containing conventional suppository bases such as cocoa butter or other glycerides.
Compositions for veterinary medicine may, for example, be formulated as intramammary preparations in either long acting or quick-release bases.
The compositions may contain from 0.1% upwards~ e.g.
~ 992 of the active material, depending on the method of administration. When the compositions comprise dosage units, each unit will preferably contain ~1229~3 50-1500 mg of the active ingredient. The dosage as employed for adult human treatment will preferably range from 500 to 6000 mg per day, depending on the route and fre~uency of admin;stration. For example, in adult human treatment 1000 to 3000 mg per day administered intravenously or intramuscularly will normally suffice. In treating Pseudomonas infections higher daily doses may be required.
The antibiotic compounds according to the invention may be administered in combination with other therapeutic agents such as antibiotics, for example penicillins or other cephalosporins.
The following Examples illustrate the invention.
All temperatures are in C. ~Petrol~ means petroleum ether (b.p. 40-60).
Z5~73 Preparation 1 Ethyl (Z)-2-(2-aminothiaæol 4-yl)-2-(hYdroxyimino)acetate To a stirred and ice-cooled solution of ethyl aceto~cetate (292 g) in glacial acetic acid (296 ml) was added a solution of sodium nitrite (180 g) in water (400 ml) at such a rate that the reaction temperature was maintained below 10C. Stirring and cooling were continued for about 30 min., when a solution of potassium chloride (160 g) in water (800 ml) was addedO The resulting mixture was stirred for one hour. The lower oily phase was separated and the aqueous phasewas extracted with diethyl ether. The extract was combined with the oil, washed successively with water and saturated brine, dried, and evaporated. The residual oil, which solidified on standing, was washed with petrol and dried in vacuo over potassium hydroxide, giving ethyl (Z)-2-(hydroxyimino)-3-oxobutyrate (309 g).
A stirred and ice-cooled solution of ethyl (Z)-2-(hydroxyimino)-3-oxobutyrate (150 g) in dichloromethane (400 ml) was treated dropwise with sulphuryl chloride (140 g). The resulting solution was kept at room temperature for 3 days, then evaporated.
The residue was dissolved in diethyl ether, washed with water until thewashings were almost neutral, dried, and evaporated. The residual oil (177 g) was dissolved in ethanol (500 ml) and dimethylaniline~ (77 ml) and thiourea (42 g) were added with stirring. After two hours, ~hc pr~duct wa~ collected by filtration, washed with ethanol and dried to give the title compound (73 g);
m.p.188 (decomp.).
~lZZ~7 Pre~aration 2 Ethyl (Z)-2-hydroxyimino-2-(2-tritylaminothiazol-4-y acetate, hydrochloride, Trityl chloride (16.75 g) was added portionwise over 2 hours to a stirred and cooled (-30) solution of the product of Preparation 1 (12.91 g) in dimethylformamide (28 ml) containing triethylamine (8.4 ml). The mixture was allowed to warm to 15 over one hour, stirred for a further 2 hours and then partitioned between water (500 ml) and ethyl acetate (500 ml). The organic phase was separated, washed with water (2 x 500 ml) and then shaken with lN HCl (500 ml). The precipitate was collected, washed successively with water (100 ml), ethyl acetate (200 ml) and ether (200 ml) and dried in vacuo to provide the title compound as a wh~te solid (16.4 g); m.p. 184 to 186 (decomp~.
Preparation 3 Ethyl (Z)-2-(2-t-butoxycarbonylprop-2-oxyimino)-2-(2~trityl-aminothiaæol-4-yl)acetate Potassium carbonate (34.6 g) and t-butyl 2-bromo-2-methylpropionate (24.5 g) in dimethylsulphoxide (25 ml) were added to a stirred solution under nitrogen of the product of Preparation 2 (49.4 g) in dimethylsulphoxide (200 ml) and the mixture was stirred at room temperature for 6 hours. The mixture was poured into water (2 1), stirred for 10 mins., and filtered. The solid was washed with water and dissolved in ethyl acetate ~600 ~1), The solution was washed successively with water, 2N hydrochloric acid, water, and saturated brine, dried, and evaporated. The residue was recrystallised from petroleum ether (b.po 60-80) to give the title Z9'^~3 compound (34 g), m.p. 123.5 to 125 Preparation 4 (Z)-2-(2-t-Butoxycarbonylprop-2-oxyimino?-2-(2-tritylamino-thiazol-4-yl)acetic acid The produc~ of Preparation 3 (2 g) was dissolved in methanol (20 ml) and 2N sodium hydroxide (3.3 ml) was added. The mixture was refluxed for 1.5 hours and then concentrated. The residue was taken up in a mixture of water (50 ml), 2N hydrochloric acid (7 ml), and ethyl acetate (50 ml). The organic phase was separated, and the aqueous phase extracted with ethyl acetate. The organic solutions were combined, washed successively with water and saturated brine, dried, and evaporated The residue was recrystallised from a mixture of carbon tetrachloride and petrol to give the title compound (1 g), m.p. 152 to 156 (decomp).
Preparation 5 Ethyl (Z)-2-(2-tritylaminothiazol-4-yl)-2-(1-t-butoxY-carbonylcyclobut-l-oxyimino) acetate.
The product of Preparation 2 (55.8 g) was stirred under nitrogen in dimethylsulphoxide (400 ml) with potassium carbonate (finely ground, 31.2 g) at room temperature. After 30 minutes, t-butyl l-bromocyclobutane carboxylate (29.2 g) was added. After 8 hours further potassium carbonate (31.2 g) was added. More potassium carbonate (6 x 16 g portions) was added during the next three days and further t-butyl l-bromocyclobutane c3~boxy1ate ~3.45 g) was added after 3 days. After 4 days in all, the mixture was poured into ice-water (ca.
3 litres) and the solid was collected by filtration and ~122973 washed well with water and petrol. The solid was dissolved in ethyl acetate and the solution washed with brine (twice), dried with magnesium sulphate and evaporated to a foam, This foam was dissolved in ethyl acetate-petrol(1:2) and filtered through silica gel (S00 g).
Evaporation gave the title compound (60 g) as a foam, v (CHBr3) 3400 (NH) and 1730 cm (ester).
Preparation 6 (Z)-2-(1-t-Butoxycarbonylcyclobut-l-oxyimino~-2-(2-trityl-aminothiazol-4-yl) acetic acidO
A mixture of the product of Preparation 5 (3.2g) and potassium carbonate (1.65 g) was refluxed in methanol (180 ml) and water (20 ml) for 9 hours and the mixture was cooled to room temperatureO The mixture was concentrated and the residue partitioned between ethyl lS acetate and water, to which was added 2N HCl (12.2 ml)O
The organic phase was separated and the aqueous phase extracted with ethyl acetate. The combined organic extracts were washed with saturated brine, dried and evaporated to give the title compound (2.3 g);
(ethanol) 265 nm (Elcm 243)-llZZ9~3 Example l a) Diphenylmethy1_(6R~7R)-7-r(Z~-2-(1-t-butoxycarbonyl-cyclobut-l-oxyimino)_2-(2-tritylaminothiazol-4-yl) acetamido],3-(l methyltetrazol-5-~_thiomethyl)ceph-3-em-4-carboxylate To a solution of the product of Preparation 6 (4.5 g) in tetrahydrofuran (lOO ml) was added l-hydroxybenzo-triazole hydrate (1.18 g), followed by dicyclohexylcarbo-diimide (2.39 g). The resulting suspension was treated with diphenylmethyl 7-amino-3-(1-methyltetrazol-5-ylthiomethyl) ceph-3-em-4-carboxylate (3.82 g) and stirred at 25- for 24 h. The mixture was filtered and evaporated, and the residue was chromatographed over silica gel, using ethyl acetate-petrol (1:2 to 1:1) as the eluant.
11229~3 The product (4.52 g) was crystallised from ether to give the title compound, m.p. 139- (decomp.); [a~D (DMSO) - 68-;
A (EtOH) 260 nm (inf.) ~E 22,000).
b) (6R lR)-7-r(Z~2-(l-Carboxycyclobut-l-oxyimino)-2-(_2-t (l-methyltetrazol-5-ylthiomethyl)-ceph-3-em-4 carboxylic acid.
The produc~ of Stage a) (2.445 g) in anisole (10 ml) was treated with trifluoroacetic acid (20 ml), and the mixture was stirred at 25- for 1 h. Most of the volatile solvent was removed in vac~lo and the residue was dissolved in ethyl acetate, washed thoroughly with water, dried, and evaporated~ The residual oil was treated with petrol and the resulting solid was collected, and dissolved in ethyl acetate. The solution was washed thoroughly with water, dried, and evaporated to give the title compound, (1.21 g),m.p. 143- (decomp.) A max (pH 6 buffer) 258 (inf) (~ 20,530), 305 nm (inf) (~6,450) c) (6R,7R)-7-~(Z)-2-~2-Aminothiazol-4-yl)-2-(1-carboxy-cYclobut-l-oxyimino)acetam dol-3-(l-methv]tetrazol-5-. .
vlthiomethyl ~ -3-em-4-carboxvl;c acicl.
The product from Stage b) (1.155 g) was dissolYed in 90~/O formic acid (15 ml) and treated with water (4 ml). The mixture was stirred at 25' for 1 h, then poured into water and filtered. The filtrate was extractecl with dichloro-methane, and the aqueous phase was concentrated under reduced pressure. The resulting solid was col]ected and dried to give the title compound (407 mg), [a~D (DMSO) - 65-, Amax (pH 6 buffer) 240 ( 18,350), 252 (inf.) (~ 18,050), 302.5 nm (inf) ( 7,600).
llZ~73 More of the title compound was obtained by evaporation of the mother liquors, and by evaporation of the aqueous washings from Stage b) aboveO
Example 2_ a) D ~
carbonylprop-2-oxvimino~-2-(2-tritylaminothiazol-4-vl)acetamido~-3-(l-methyltetrazol-5-ylthiomethyl) ce~4~:
To a stirred solution of the product of Preparation 4 (4.39g) and l-hydroxybenzotriazole hydrate (1 18g) in dry tetrahydrofuran (lOOml) was added diphenylmethyl (6R,7R)-7-amino-3-(1-methyltetrazol-5-ylthiomethyl)ceph-3-em-4-carboxylate (3.8g), followed by a solution of dicyclo-hexylcarbodiimide (2.37g) in tetrahydrofuran (50ml), After 24 h, the mixture was filtered and the filtrate was evaporated. Chromatography of the residue over silica gel using ethyl acetate-petroleum ether(b.p. 60-80-) (1:1 to 3:2) as eluant, followed by recrystallisation from ether, yielded the title compound (2.8g), m.p. 141, [~D (DMS0)-73-.
b~ (6R~/R)-7-r(z)-2-(2-Aminothiazol-4-yl) 2-(2-carboxyprl~mino)acetamido l-3-(l.-met Yl-tetrazol-5-ylthiomethyl~ceDh-3-em-4-carboxylic acid.
_ _ . . _~
The product of Stage a) (2.0g) in anisole (lOml) was stirred with trifluoroacetic acid (20ml) at 25-. After 2.5 h, the volatile solvent was removed in vacuo and the residue was partitioned between water and ethyl acetate.
~he aqueou~ phase was evaporated to give the title compound (920mg), [~D (DMSO)-58-, A (pH 6 buffer) 232 (inf) ( 17,860), 256nm (inf) ~ 16,280).
2g~73 PHARMACY EXAMPLES
.
EXAMPL~ A - Dr~ Powder for Ini~ction Formula Per Vial .
(6R,7R)-7-L(Z)-2-(2-aminothiazol-4-yl)-2-(2-carboxyprop-2-oxyimino)acetamido]-3-(1-mPthyltetrazol-5-ylthiomethyl) ceph-3-em-4-carboxylic acid 500mg Sodium Carbonate, anhydrous 113mg Method Blend the sterile cephalosporin antibiotic with sterile sodium carbonate under aseptic conditions, Fill aseptically into glass vials under a blanket of sterile nitrogen, Close the vials using rubber discs or plugs, held in position by aluminium overseals, thereby preventing gaseous exchange or ingress of micro-organisms, Reconstitute the product by dissolving in Water for Injections or other suitable sterile vehicle shortly before administration, EXAMPLE B - Dry Powder for Iniection _ Fill sterile (6R,7R)-7-~(Z)-2-(2-aminothiazol-4-yl)-2-(1-carboxycyclobut-1-oxyimino)acetamido]-3-(1-methyltetrazol-5-ylthiomethyl)ceph-3-em-4-carboxylic acid, disodium salt into glass vials such that each vial contains an amount equivalent to 500mg of the antibiotic acid, Carry out the filling aseptically under a blanket of sterile nitrogen, Close the vials using rubber discs or plugs, held in position by aluminium overseals, thereby preventing gaseous exchange or ingress of micro-organisms.
Reconstitute the product by dissolving in Water for Injections or other suitable sterile vehicle shortly before administration.
We have now discovered that by an appropriate selection of a small number of particular groups at the ~q~
7~-position in combination with a heterocyclic-substituted thiomethyl group at the 3-position, cephalosporin compounds having particularly advantageous activity (described in more detail below) against a wide range of commonly encountered pathogenic organisms may be obtained.
The present invention provides cephalosporin antibiotics of the general formula =~L--C r CO ~ NH ~-- H H
N\ ~ ~ 1 !~ ~ (I) O.C.COOH COOH
Rb (wherein Ra and Rb, which may be the same or different, each represent a Cl 4 alkyl group (preferably a straight chain alkyl group, i.e. a methyl, ethyl, n-propyl or n-butyl group and particularly a methyl or ethyl group) or Ra and Rb together with the carbon atom to which they are attached form a C3 7 cycloalkylidene group, preferably a C3 5 cycloalkylidene group;
and Y represents a C-linked tetrazolyl group optionally substituted by a Cl 4 alkyl group) and non-toxic salts and non-toxic metabolically labile esters thereof.
The compounds according to the invention are ~y~
isomers. The sYn isomeric form is defined by the ~ -5-~ .~
:11229173 configuration of the group i ! ' ' .
I 1~
with respcct to the carboxamido group. In this specification the ~y~ configuration is denoted structurally as J ~2 S N
\O . (' . (`0()1~
It will be understood that since the compo~mds accord-ing to the invention are geometric isomers, some admixture with the corresponding anti isomer may occur.
The invention also includes within its scope the solvates (especially the hydrates) of the compounds of formula (I). It also includes within its scope salts of esters of compounds of formula (I).
The compounds according to the present invention may exist in tautomeric forms (for example in respect of the 2-~minothiazolyl group) and it will be understood that such tautomeric forms, e.g. the 2-iminothiazolinyl ~122~73 form, are included within the scope of the invention.
It will also be appreciated that when Ra and Rb in the above formula represent different Cl 4 alkyl groups, the carbon atom to which they are attached will comprise a centre of asymmetry. Such compounds are diastereoisomeric and the present invention embraces individual diastereoisomers of these compounds as well as mixtures thereof.
In formula (I) above, the heterocyclic ring represented by Y may, if desired, be substituted by a Cl 4 alkyl group, e.g.
a methyl group.
The compounds according to the invention exhibit broad spectrum antibiotic activity. Against gram-~1122973 negative organisms the activity is unusually high.This high activity extends to many ~-lactamase-producing gram-negative strains. The compounds also possess high stability to ~-lactamases produced by a range of gram-negative organisms.
Compounds according to the invention have been found to exhibit unusually high activity against strains of Pseudomonas organisms, e.gO strains of Pseudomonas aeruginosa as well as high activity against various members of the Enterobacteriaceae (e.g, strains of Escherichia coli, ~lebsiella pneumoniae, Salmonella typhimurium, S~i&~ sonnei, _ Enterobacter cloacae, Serratia marcescens,Providence species, Proteus mirabilis and especially indole-positive 15 Proteus organisms such as Proteus vulgaris and Proteus _ _ morganii),and strains of Haemophilus in~luenzae.
~12Z97;~
The antibiotic properties of the compounds according to the invention compare very favourably with those of the ami.noglycosides s~lch as am;kac;.n or gentamicin, In particular, thi.s applies to their activity against strains of various Pseudomonas organisms which are not susceptable to the majority of exist-ing commercially available antibiotic compounds.
Unlike the aminoglycosides, cephalospori.n anti.biotics normally exhibi.t low toxicity in man, The use of amino-glyco~sides in human therapy tends to be limited orcompli.caLed by the hightoxici~y c~ these antibiotics.
The cepllalospori.n antib;otics of the present imvelltion thus possess potentially great advantages over the ami.lloglycosi.des~
~on-toxic salt derivatives which may be formed by reaction of either or both of the carboxyl groups present i,n the compounds of general ~orrnula (I) include inorganic base salts such as alkali metal sa]-s (e.g.
sodium and potassium salts) and alkaline earth Inetal salts (e.g. calci.um salts); an-l;no aci,d ~salts (e.g. ]y.sine and arginine sa]ts); organi.c base salts (e.g. ploca;.lle, phenylethyl-benzy]amine, dibenzylethylenecliarnine, ethanolamine, diethanolamine and N-methylglucosamine salts). Other non-toxic salt derivatives include acid addition salts, e.g. formed with hydrochloric, hydrobromic, sulphuric, nitric, phosphoric, formic and trifluoroacetic acids. The salts may also be in the form of resinates formed with, for example, a polystyrene resin or cross-]inked polystyrene divinylbenzene copolymer resin containing amino or quarternary amino 10 groups or sulphonic acid groups, or with à resin containing carboxyl groups, e.g. a polyacrylic acid resin. Soluble base salts (e.g. alkali metal salts such as the sodium salt) of compounds of formula (I)`
may be used in therapeutic applications because of the rapid distribution of such salts in the body upon administration. Where, however, insoluble salts of compounds (I) are desired in a particular application, e.g. for use in depot preparations, such salts may be formed in conventional manner, for example with 20 appropriate organic amines.
These and other salt derivatives such as the salts with toluene-~-sulphonic and methanesulphonic acids may be employed as intermediates in the prepara-tion and/or purification of the present compounds of 25 formula (I), for example in the processes described below, Non-toxic metabolically labile ester derivatives which may be formed by esterification of either or both carboxyl groups in the parent compound of formula (I) ~iZ2~373 include acyloxyalkyl esters, e.g. lower alkanoyloxy-methyl or -ethyl esters such as acetoxy-methyl or -ethyl or pivaloyloxy-methyl esters. In addition to the above ester derivatives, the present invention includes within its scope compounds of formula (I) in the form of other physiologically acceptable equivalents, i.e. physiologically acceptable compounds which, like the meta-bolically labile esters, are converted in vivo into the parent antibiotic compound of formula (I).
:1~22~
Examples of preferred compounds according to the present invention include the ollowing compounds of formula (I) and their non-toxic salts and non-toxic metabolically labile esters, namely:-(6R,7R)-7-[(Z~-2-(2-aminothiazol-4-yl)-2-(2-carboxyprop-2-oxyimino) acetamido~-3~ methyltetrazol-5-ylthiomethyl) ceph-3-em-4-carboxylic acid (6R,7R)-7-~(Z)-2-(2-aminothiazol-4-yl)-2-(1-carboxycyclo-but-l-oxyimino) acetamido~-3~ methyltetrazol-5-ylthio-methyl) ceph-3-em-4-carboxylic acid, Other compounds according to the present invention include for example those wherein the groups R , R and Y in formula (I) are as follows:-:l~Z~ 3 _ . _ . . _ . _ _ . , . . _ .
Ra Rb Y
. __ . . . . __ . _ . _ . . __, ~) ,Alkyl groups ~ . .
~3 ~ C2H5 l.methyl-tetrazol-5-yl-b~ Cycloalkylidene groups __ . __ .
cyclopropylidene l-methyl-tetrazol-5-yl cyc lopentylidene . . . _ . ._ ~lZ2973 The compounds of formula (I) may be used for treating a variety of diseases caused by pathogenic bacteria in human beings and animals, such as respiratory tract infections and urinary tract infections.
According to another embodiment of the invention we provide a process for the preparation of an antibiotic compound of general formula (I) as hereinbefore defined or a non-toxic salt (including internal salt) or non-toxic metabolically labile ester thereof which comprises (A) a~ylating a compound of the formula 1.~ 11 H2 = B
N ~ SY
COORl (II) [wherein Y is as defined above; B is )S or ) S--~ 0 (~-or ~-); R represents hydrogen or a carboxyl blocking group, e.g. the residue of an ester-forming aliphatic or araliphatic alcohol or an ester-forming phenol, silanol or stannanol (the said alcohol, phenol, silanol or stannanol preferably containing 1-20 carbon atoms); and the dotted line bridging the 2-, 3-, and 4-positions indicates that the compound is a ceph-2-em or ceph-3-em compound] or a salt, e.g. an acid addition salt (formed with, for example, a mineral acid such as hydrochloric, hydrobromic, sulphuric, nitric or phosphoric acid or an organic acid such as methanesulphonic or toluene-p-sulphonic acid) or an N-silyl derivative thereof, with an acid of formula ~2~973 S N
C.COOH
Il a N R
\ O.C.COOR (III) Ib (wherein Ra and Rb are as hereinbefore dcfined; R2 rcpresents a carboxyl blockin~ group, e.g. as described for R ; and R is an amino or protected amino group) or with an acylating agent corresponding thereto; (B) reacting a compound of formula S N
\ / -C.~O.~ ~ B ~
N Ra oJ ~ CI~ X
\ o.~.. cooR4a (,ooR4 Rb (IV) (wherein R , Rb, R3, B and thc dotted llne are as dcfined above; R4 and R4a may lndependently rcpresent hydrogen or a carboxyl blocking group; and X is a replaceable residue of a nucleophile, e.g. an acetoxy or dichloroacetoxy group or a halogen atom such as chlorine, bromine or iodine) or a salt thereof with a sulphur nucleophile serving to form a group of formula -CH2SY (wherein Y is as defined above~
at the 3-position; whereafter, if neoessary-and/or desired in 1~229'73 each instance, any of the following reactions, in any appropriate sequence, are carried out:-i) conversion of a Q -isomer into the desired Q -isomer, S ii) reduction of a compound wherein B is >S ? O to form a compound wherein B is >S, iii) conversion of a carboxyl group into a non-toxic salt or non-toxic metabolically labile ester function, and iv) removal of any carbox~ blocking and/or N-protecting groups.
In the above-described process (A), the starting material of formula (II) is preferably a compound wherein B is >S and the dotted line represents a ceph-3-em compound, Acylating agents which may be ernployed in the preparation of compo~mds of forlnula (I) include acid halides, particularly acid chlorides or bromides. Sucll acylating agents may be prepared by reacting an acid (III) or a salt thereof with a halogenating agent e.g.
phosphorus pentachloride, thionyl chloride or oxalyl chloride.
Acylations employing acid halides may be effected in aqueous and non-aqueous reaction media, conveniently at temperatures of from -50 to +50C, preferably -20 to +30C, if desired in the presence of an acid binding agent. Suitable reaction media include aqueous ketones such as aqueous acetone, esters such as ethyl acetate, halogenated hydrocarbons such as methylene chloride, amides such as dimethylacetamide, nitriles such as acetonitrile, or mixtures of two or more such solvents.
Suitable acid binding agents include tertiary amines (e.g. triethylamine or dimethylaniline), inorganic bases (e.g. calcium carbonate or sodi~lm bicarbonate), and oxiranes such as lower 1,2-alkylene oxides (e.g. ethylene oxide or propylene oxide) which bind hydrogen halide liberated in the acylation reaction.
Acids of formula (III) may themselves be used as acylating agents in the preparation of compounds of 1~2~973 1~
formula (I). Acylations employing acids (III) are desirably conducted in the presence of a condensing agent, for example a carbodiimide such as N,N'-dicyclohexyl-carbodiimide or N-ethyl-N'-y-dimethylaminopropylcarbodiimide;
a carbonyl compound such as carbonyldiimidazole; or an isoxazolium salt such as N-ethyl-5-phenylisoxazolium perchlorate.
Acylation may also be effected with other amide-forming derivatives of acids of formula (III) such as, for example, an activated ester, a symmetrical anhydride or a mixed anhydride (e.g. formed with pivalic acid or with a haloformate, such as a lower alkylhaloformate). Mixed anhydrides may also be formed with phosphorus acids (for example phosphoric or phosphorous acids), sulphuric acid or aliphatic or aromatic sulphonic acids (for example toluene-p-sulphonic acid). An activated ester may conveniently be formed in situ using, for example, l-hydroxybenzotriazole in the presence of a condensing agent as set out above. Alternatively, the activated ester may be preformed.
Acylation reactions involving the free acids or their above-mentioned amide-forming derivatives are desirably effected in an anhydrous reaction medium, e.g.
methylene chloride, tetrahydrofuran, dimethylformamide or acetonitrile.
If desired, the above acylation reactions may be carried out in the presence of a catalyst such as 4-dimethylaminopyridine.
The acids of formula (III) and acylating agents corresponding thereto may, if desired, be prepared and employed in the form of their acid addition salts. Thus, for example, acid chlorides may conveniently be emp]oyed li;~Z97j~
as their hydrochloride salts, and acid bromides as their hydrobromide salts.
In process (B) above, the sulphur nucleophile may be used to displace a wide variety of substituents X
from the cephalosporin of formula (IV~. To some extent the facility of the displacement is related to the pKa of the acid HX from which the substituent is derived. Thus, atoms or groups X derived from strong acids tend, in general, to be more easily displaced than atoms or groups derived from weaker acids. The facility of the displacement is also related, to some extent, to the precise character of the sulphur nucleophile. The latter nucleophile may be employed for example in the form of an appropriate thiol or thione.
The displacement of X by the sulphur nucleophile may conveniently be effected by maintaining the reactants in solution or suspension. The reaction is advantageously effected using from 1 to 10 moles of the nucleophile.
Nucleophilic displacement reactions may conveniently be carried out on those compounds of formula (IV) wherein the substituent X is a halogen atom or an acyloxy group, for example as discussed below.
Acylo~ rou~s Compounds of formula (IV) wherein X is an acetoxy 2~ group are convenient starting materials for use in the nucleophilic displacement reaction with the sulphur nucleophile. Alternative starting materials in this class include compounds of formula (IV) in which X is the residue of a 9ubstituted acetic acid e.g. chloroacetic acid, dichloroacetic acid and trifluoroacetic acid.
Displacement reactions on compounds (IV) possessing X substitue~ts of this class, particularly in the case where liZ2973 X is an acetoxy group, may be facilitated by the presence in the reaction medium of iodide or thiocyanate ions.
The substituent X may also be derived from formic acid, a haloformic acid such as chloroformic acid,or a carbamic acid.
When using a compound of formula (IV) in which X represents an acetoxy or substituted acetoxy group, it is generally desirable that the group R4 in formula (IV) should be a hydrogen atom and that B should represent ~S.
In this case, the reaction is advantageously effected in an aqueous medium.
Under aqueous conditions, the pH value of the reaction solution is advantageously maintained in the range 6-g, if necessary by the addition of a base. The base is conveniently an alkali metal or alkaline earth metal hydroxide or bicarbonate such as sodium hydroxide or sodium bicarbonate.
When using compounds of formula (IV) in which X
is an acetoxy group, the reaction is conveniently effected at a ter.~perature of 30C to 110C, preferably 50 to 80C.
- Halo~ens Compounds o~ ~orrnula (IV) in which X is a chlorine, bromine or iodine atom can also be conveniently used as starting materials in the nucleophilic displacement reaction with the sulphur nucelophile. When using compounds of formula (IV) in this class, B may represent ~ S and R4may represent a carboxyl b]ocking group. The reaction is conveniently effected in a non-aqueous medlum which preferably comprises one or more organic solvents, advantageously of a polar nature such as ethers, e.g. dioxan or tetrahydrofuran, esters, e.g.
....
lJ Z2973 ethyl acetate, amides, e.g. formamide and N,N-dimethyl-formamide, and ketones e.g. acetone. Other suitable organic solvents are described in more detail in British Patent Specification No. 1,326,531. The reaction medium shou]d be neither extremely acidic nor extremely basic.
When using compounds of formula (IV) in which X
is a halogen atom as described above, the reaction is conveniently effected at a temperature of -20 to +60, preferably 0 to ~30C.
The react;on is generally effected in the presence of an acid scavenging agent for example a base such as triethylamine or calcium carbonate.
~ZZ9~3 The reacti.on product may be separated from the reaction mixture, which may contain, for example, unchanged cephalosporin starting material and other substances, by a variety of processes including recrystalli.sation, ionophoresis~ column chromatography and use of ion-exchangers (for example by chromatography on ion-exchange resins) or macroreticular resins.
~ -Cephalosporin ester derivatives obtained in accordance with the process of the invention may be converted lnto the corresponding ~ -derivative by, for example, treatment of the ~ -ester with a base, such as pyridine or triethylamine.
A ceph-2-em reaction product may also be oxidised to yield the corresponding ceph-3-em l-oxide, for example by reaction with a peracid, e.g. peracetic or m chloroperbenzoic acid; the resulting sulphoxide may, if desired, subsequently be reduced as described hereinafter to yield the corresponding ceph-3-em sulphide.
Where a compound is obtained in which B is > S ~ 0 this may be converted to the corresponding sulphide by, for example, reduction of the corresponding acyloxysulphonium or alkoxysulphonium salt prepared in situ by reaction with e.g. acetyl chloride in the case of an acetoxysulphonium salt, reduction being effected by, for example, sodium dithionite or by iodide ion as in a solution of potassium iodide in a water-miscible solvent e.g. acetic acid, acetone, tetrahydrofuran, dioxan, dimethylformamide or dimethylacetamide. The reaction may be effected at a temperature of from -20 to +50C.
Metabolically labile ester derivatives of the compounds of formula (I) may be prepared by reacting a compound of formula (I) or a salt or protected derivative thereof with the appropriate esterifying agent such as an acyloxyalkyl halide (e.g. iodide) conveniently in an inert organic solvent such as dimethylformamide or acetone, followed,where necessary9 by removal of any protecting groups.
Base salts of the compound of formula (I) may be formed by reacting an acid of formula (I) with an appropriate base. Thus, for example, sodium or potassium salts may be prepared using the respective 2-ethylhexanoate or hydrogen carbonate salt. Acid addition salts may be prepared by reacting a compound of formula (I) or a metabolically labile ester derivative thereof with the appropriate acid~
Where a compound of formula (I) is obtained as a mixture of isomers, the ~y~ isomer may be obtained by, ~Z~973 2~ -for example, conventional methods such as crystallisation or chromatography.
For use as starting materials for the preparation of compounds of general formula (I) according to the invention, compounds of general formula (III) and acid halides and anhydrides corresponding thereto in their ~y_ isomeric form or in the form of mixtures of the syn isomers and the corresponding anti isomers containing at least 90% of the syn isomer are preferably used.
Acids of formula (III) (provided that R and R
together with the carbon atom to which they are attached do not form a cyclopropylidene group) may be prepared by etherification of a compound of formula ~s~
ooR5 !1 (v) OH
(wherein R is as hereinbefore defined and R represents a carboxyl blocking group), by reaction with a compound of general formula Ra T.c.cooR2 Rb (VI) (wherein R and R and R are as hereinbefore defined and T is halogen such as chloro, bromo or iodo;
sulphate; or sulphonate such as tosylate), followed by removal of the carboxyl blocking group R5~ Separation of isomers may be effected either before or after such ~ ..
ll~Z~73 - 25 ~
etherification. The etherification reaction is generally carried out in the presence of a base, e.g. potassium carbonate or sodium hydride, and is preferably conducted in an organic solvent, for example dimethylsulphoxide, a cyclic ether such as tetrahydrofuran or dioxan, or an N,N-disubstituted amide such as dimethylformamide. Under these conditions the configuration of the oxyimino group is substantially unchanged by the etherification reaction. The reaction should be effected in the presence of a base if an acid addition salt of a compound of formula (V) ,s used.
The base should be used in sufficient quantity to neutralise rapidly the acid in guestion.
Acids of general formula (III) may also be prepared by reaction of a compound of formula S~
~ CO.COOR ~V~I) (wherein R and R are as hereinbefore defined) with a compound of formula lRa 2 H2N.O.C.COOR (VIII) Rb (wherein Ra, Rb and R are as defined above), followed by removal of the carboxyl blocking group R , and where necessary by the separation of syn and anti isomers.
The last mentioned reaction is particularly applicable to the preparation of acids of formula (III) wherein Ra and Rb together with the carbon atom to which they are attached form a cyclopropylidene group. In this case, the relevant compounds of formula (VIII) may be prepared in conventional manner, e.g. by means of the synthesis described in Belgian Patent Specification No.
866,422 for the preparation of t-butyl l-amino-oxycyclo-propane carboxylate.
The acids of formula (III) may be converted to the corresponding acid halides and anhydrides and acid addition salts by conventional methods, for example as described hereinabove.
Where X is a halogen (i.e. chlorine, bromine or iodine) atom in formula (IV), ceph-3-em starting compounds may be prepared in conventional mamler, e.g. by halogenation of a 7~-protected amino-3-methylceph-3-em-4-carboxylic acid ester l~-oxide, removal of the 7~-protecting group, acylation of the resulting 7~-amino compound to form the desired 7~-acylamido group, e.g.
in an analogous manner to process (A) above, followed by reduction of the l~-oxide group later in the sequence.
This is described in British Patent No. 1,326,531. The corresponding ceph-2-em compounds may be prepared by the method of Dutch published Patent Application No.
6,902,013 by reaction of a 3-methylceph-2-em compound with N-bromosuccinimide to yield the corresponding 3-bromomethylceph-2-em-compound.
Where X in formula (IV) is an acetoxy group, such starting materials may be prepared for example by acylation of 7-aminocephalosporanic acid, e.g. in an analogous manner to process (A) above. Compounds of formula (IV) in which X represents other acyloxy groups can be prepared by acylation of the corresponding 3-~122~'73 hydroxymethyl compounds which may be prepared for example by hydrolysis of the appropriate 3-acetoxymethyl compounds, e.g. as described for example in British Patent Specifications Nos. 1,474,519 and 1,531,212.
Compounds of formula (II) may also be prepared in con-ventional manner, e.g. by nucleophilic displacement of a corresponding 3-acyloxymethyl or 3-halomethyl compound with the appropriate nucleophile, e.g. as described in British Patents Nos.1,012,943 and 1,241,657.
A further method for the preparation of the starting - materials of formula (II) comprises deprotecting a corresponding protected 7~-amino compound in conventional manner, e.g.
using PC15 It should be appreciated that in some of the above transformati~ns it may be necessary to protect any sensitive groups in the molecule of the compound in question to avoid undesirable side reactions. For example, during any of the reaction sequences referred to above it may be necessary to protect the NH2 group of the aminothiazolyl moiety, for example by tritylation, acylation (e.g. chloroacetylation), protonation or other conventional method. The protecting group rnay there-after be removed in any convenient way which does not cause breakdown of the desired compound, e.g. in the case of a trityl group by using an optionally halogenated carboxylic acid, e.g. acetic acid, formic acid, chloroacetic acid or trifluoroacetic acid or using a mineral acid, e.g. hydrochloric acid or mixtures of such acids, preferably in the presence of a protic solvent such as water, or, in the case of a chloro-acetyl group, by treatment with thiourea.
Carboxyl blocking groups used in the preparation of compounds of formula (I) or in the preparation of necessary starting materials are desirably groups which llZ~73 may readily be split off at a suitable stage in the reaction sequence, conveniently at the last stage. ~t may, however, be convenient in some instances to employ non-toxic metabolically labile carboxyl blocking groups such as acyloxy-methyl or -ethyl groups (e.g.
acetoxy-methyl or-ethyl or pivaloyloxymethyl) and retain these in the final product to give an appropriate ester derivative of a compound of formula (I), Suitable carboxyl blocking groups are well known in the art, a list of representative blocked carboxyl groups being included in British Patent No. 1,399,086.
Preferred blocked carboxyl groups include aryl lower alkoxycarbonyl groups such as p-methoxybenzyloxycarbonyl, p-nitrobenzyloxycarbonyl and diphenylmethoxycarbonyl;
lower alkoxycarbonyl groups such as t-butoxycarbonyl; and lower haloalkoxycarbonyl groups such as 2,2,2-trichloroethoxycarbonyl. Carboxyl blocking group(s) may subsequently be removed by any of the appropriate methods disclosed in the literature; thus, for example, acid or base catalysed hydrolysis is applicable in many cases, as are enzymically-catalysed hydrolyses.
The antibiotic compounds of the invention may be formulated for administration in any convenient way~ by analogy with other antibiotics and the invention therefore includes within its scope pharmaceutical compositions comprising an antibiotic compound in accordance with the invention adapted for use in human or veterinary medicine.
Such compositions may be presented for use in conventional ~anner ~ith the aid of any necessary pharmaceutical carriers or excipients.
The antibiotic compounds according to the invention 1~229~j3 2g may be formulated for injection and may be presented in unit dose form in ampoules, or in muLti-dose containers, if necessary with an added preservative. The compositions may also take such forms as suspensions, solutions, or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilising and/or dispersing agents. Alternatively the active ingredient may be in powder form for reconstitution with a suitable vehicle, e.g. sterile, pyrogen-free water, before use.
If desired, such powder formulations may contain an appropriate non-toxic base in order to improve the water-solubility of the active ingredient andlor to ensure that when the powder is reconstituted with water, the pH of the resulting aqueous formulation is physiologically acceptable. Alternatively the base may be present in the water with which the powder is reconstituted. The base may be, for example, an inorganic base such as sodium carbonate, sodium bicarbonate or sodium acetate, or an organic base such as lysine or lysine acetate.
The antibiotic compounds may also be formulated as suppositories, e.g~ containing conventional suppository bases such as cocoa butter or other glycerides.
Compositions for veterinary medicine may, for example, be formulated as intramammary preparations in either long acting or quick-release bases.
The compositions may contain from 0.1% upwards~ e.g.
~ 992 of the active material, depending on the method of administration. When the compositions comprise dosage units, each unit will preferably contain ~1229~3 50-1500 mg of the active ingredient. The dosage as employed for adult human treatment will preferably range from 500 to 6000 mg per day, depending on the route and fre~uency of admin;stration. For example, in adult human treatment 1000 to 3000 mg per day administered intravenously or intramuscularly will normally suffice. In treating Pseudomonas infections higher daily doses may be required.
The antibiotic compounds according to the invention may be administered in combination with other therapeutic agents such as antibiotics, for example penicillins or other cephalosporins.
The following Examples illustrate the invention.
All temperatures are in C. ~Petrol~ means petroleum ether (b.p. 40-60).
Z5~73 Preparation 1 Ethyl (Z)-2-(2-aminothiaæol 4-yl)-2-(hYdroxyimino)acetate To a stirred and ice-cooled solution of ethyl aceto~cetate (292 g) in glacial acetic acid (296 ml) was added a solution of sodium nitrite (180 g) in water (400 ml) at such a rate that the reaction temperature was maintained below 10C. Stirring and cooling were continued for about 30 min., when a solution of potassium chloride (160 g) in water (800 ml) was addedO The resulting mixture was stirred for one hour. The lower oily phase was separated and the aqueous phasewas extracted with diethyl ether. The extract was combined with the oil, washed successively with water and saturated brine, dried, and evaporated. The residual oil, which solidified on standing, was washed with petrol and dried in vacuo over potassium hydroxide, giving ethyl (Z)-2-(hydroxyimino)-3-oxobutyrate (309 g).
A stirred and ice-cooled solution of ethyl (Z)-2-(hydroxyimino)-3-oxobutyrate (150 g) in dichloromethane (400 ml) was treated dropwise with sulphuryl chloride (140 g). The resulting solution was kept at room temperature for 3 days, then evaporated.
The residue was dissolved in diethyl ether, washed with water until thewashings were almost neutral, dried, and evaporated. The residual oil (177 g) was dissolved in ethanol (500 ml) and dimethylaniline~ (77 ml) and thiourea (42 g) were added with stirring. After two hours, ~hc pr~duct wa~ collected by filtration, washed with ethanol and dried to give the title compound (73 g);
m.p.188 (decomp.).
~lZZ~7 Pre~aration 2 Ethyl (Z)-2-hydroxyimino-2-(2-tritylaminothiazol-4-y acetate, hydrochloride, Trityl chloride (16.75 g) was added portionwise over 2 hours to a stirred and cooled (-30) solution of the product of Preparation 1 (12.91 g) in dimethylformamide (28 ml) containing triethylamine (8.4 ml). The mixture was allowed to warm to 15 over one hour, stirred for a further 2 hours and then partitioned between water (500 ml) and ethyl acetate (500 ml). The organic phase was separated, washed with water (2 x 500 ml) and then shaken with lN HCl (500 ml). The precipitate was collected, washed successively with water (100 ml), ethyl acetate (200 ml) and ether (200 ml) and dried in vacuo to provide the title compound as a wh~te solid (16.4 g); m.p. 184 to 186 (decomp~.
Preparation 3 Ethyl (Z)-2-(2-t-butoxycarbonylprop-2-oxyimino)-2-(2~trityl-aminothiaæol-4-yl)acetate Potassium carbonate (34.6 g) and t-butyl 2-bromo-2-methylpropionate (24.5 g) in dimethylsulphoxide (25 ml) were added to a stirred solution under nitrogen of the product of Preparation 2 (49.4 g) in dimethylsulphoxide (200 ml) and the mixture was stirred at room temperature for 6 hours. The mixture was poured into water (2 1), stirred for 10 mins., and filtered. The solid was washed with water and dissolved in ethyl acetate ~600 ~1), The solution was washed successively with water, 2N hydrochloric acid, water, and saturated brine, dried, and evaporated. The residue was recrystallised from petroleum ether (b.po 60-80) to give the title Z9'^~3 compound (34 g), m.p. 123.5 to 125 Preparation 4 (Z)-2-(2-t-Butoxycarbonylprop-2-oxyimino?-2-(2-tritylamino-thiazol-4-yl)acetic acid The produc~ of Preparation 3 (2 g) was dissolved in methanol (20 ml) and 2N sodium hydroxide (3.3 ml) was added. The mixture was refluxed for 1.5 hours and then concentrated. The residue was taken up in a mixture of water (50 ml), 2N hydrochloric acid (7 ml), and ethyl acetate (50 ml). The organic phase was separated, and the aqueous phase extracted with ethyl acetate. The organic solutions were combined, washed successively with water and saturated brine, dried, and evaporated The residue was recrystallised from a mixture of carbon tetrachloride and petrol to give the title compound (1 g), m.p. 152 to 156 (decomp).
Preparation 5 Ethyl (Z)-2-(2-tritylaminothiazol-4-yl)-2-(1-t-butoxY-carbonylcyclobut-l-oxyimino) acetate.
The product of Preparation 2 (55.8 g) was stirred under nitrogen in dimethylsulphoxide (400 ml) with potassium carbonate (finely ground, 31.2 g) at room temperature. After 30 minutes, t-butyl l-bromocyclobutane carboxylate (29.2 g) was added. After 8 hours further potassium carbonate (31.2 g) was added. More potassium carbonate (6 x 16 g portions) was added during the next three days and further t-butyl l-bromocyclobutane c3~boxy1ate ~3.45 g) was added after 3 days. After 4 days in all, the mixture was poured into ice-water (ca.
3 litres) and the solid was collected by filtration and ~122973 washed well with water and petrol. The solid was dissolved in ethyl acetate and the solution washed with brine (twice), dried with magnesium sulphate and evaporated to a foam, This foam was dissolved in ethyl acetate-petrol(1:2) and filtered through silica gel (S00 g).
Evaporation gave the title compound (60 g) as a foam, v (CHBr3) 3400 (NH) and 1730 cm (ester).
Preparation 6 (Z)-2-(1-t-Butoxycarbonylcyclobut-l-oxyimino~-2-(2-trityl-aminothiazol-4-yl) acetic acidO
A mixture of the product of Preparation 5 (3.2g) and potassium carbonate (1.65 g) was refluxed in methanol (180 ml) and water (20 ml) for 9 hours and the mixture was cooled to room temperatureO The mixture was concentrated and the residue partitioned between ethyl lS acetate and water, to which was added 2N HCl (12.2 ml)O
The organic phase was separated and the aqueous phase extracted with ethyl acetate. The combined organic extracts were washed with saturated brine, dried and evaporated to give the title compound (2.3 g);
(ethanol) 265 nm (Elcm 243)-llZZ9~3 Example l a) Diphenylmethy1_(6R~7R)-7-r(Z~-2-(1-t-butoxycarbonyl-cyclobut-l-oxyimino)_2-(2-tritylaminothiazol-4-yl) acetamido],3-(l methyltetrazol-5-~_thiomethyl)ceph-3-em-4-carboxylate To a solution of the product of Preparation 6 (4.5 g) in tetrahydrofuran (lOO ml) was added l-hydroxybenzo-triazole hydrate (1.18 g), followed by dicyclohexylcarbo-diimide (2.39 g). The resulting suspension was treated with diphenylmethyl 7-amino-3-(1-methyltetrazol-5-ylthiomethyl) ceph-3-em-4-carboxylate (3.82 g) and stirred at 25- for 24 h. The mixture was filtered and evaporated, and the residue was chromatographed over silica gel, using ethyl acetate-petrol (1:2 to 1:1) as the eluant.
11229~3 The product (4.52 g) was crystallised from ether to give the title compound, m.p. 139- (decomp.); [a~D (DMSO) - 68-;
A (EtOH) 260 nm (inf.) ~E 22,000).
b) (6R lR)-7-r(Z~2-(l-Carboxycyclobut-l-oxyimino)-2-(_2-t (l-methyltetrazol-5-ylthiomethyl)-ceph-3-em-4 carboxylic acid.
The produc~ of Stage a) (2.445 g) in anisole (10 ml) was treated with trifluoroacetic acid (20 ml), and the mixture was stirred at 25- for 1 h. Most of the volatile solvent was removed in vac~lo and the residue was dissolved in ethyl acetate, washed thoroughly with water, dried, and evaporated~ The residual oil was treated with petrol and the resulting solid was collected, and dissolved in ethyl acetate. The solution was washed thoroughly with water, dried, and evaporated to give the title compound, (1.21 g),m.p. 143- (decomp.) A max (pH 6 buffer) 258 (inf) (~ 20,530), 305 nm (inf) (~6,450) c) (6R,7R)-7-~(Z)-2-~2-Aminothiazol-4-yl)-2-(1-carboxy-cYclobut-l-oxyimino)acetam dol-3-(l-methv]tetrazol-5-. .
vlthiomethyl ~ -3-em-4-carboxvl;c acicl.
The product from Stage b) (1.155 g) was dissolYed in 90~/O formic acid (15 ml) and treated with water (4 ml). The mixture was stirred at 25' for 1 h, then poured into water and filtered. The filtrate was extractecl with dichloro-methane, and the aqueous phase was concentrated under reduced pressure. The resulting solid was col]ected and dried to give the title compound (407 mg), [a~D (DMSO) - 65-, Amax (pH 6 buffer) 240 ( 18,350), 252 (inf.) (~ 18,050), 302.5 nm (inf) ( 7,600).
llZ~73 More of the title compound was obtained by evaporation of the mother liquors, and by evaporation of the aqueous washings from Stage b) aboveO
Example 2_ a) D ~
carbonylprop-2-oxvimino~-2-(2-tritylaminothiazol-4-vl)acetamido~-3-(l-methyltetrazol-5-ylthiomethyl) ce~4~:
To a stirred solution of the product of Preparation 4 (4.39g) and l-hydroxybenzotriazole hydrate (1 18g) in dry tetrahydrofuran (lOOml) was added diphenylmethyl (6R,7R)-7-amino-3-(1-methyltetrazol-5-ylthiomethyl)ceph-3-em-4-carboxylate (3.8g), followed by a solution of dicyclo-hexylcarbodiimide (2.37g) in tetrahydrofuran (50ml), After 24 h, the mixture was filtered and the filtrate was evaporated. Chromatography of the residue over silica gel using ethyl acetate-petroleum ether(b.p. 60-80-) (1:1 to 3:2) as eluant, followed by recrystallisation from ether, yielded the title compound (2.8g), m.p. 141, [~D (DMS0)-73-.
b~ (6R~/R)-7-r(z)-2-(2-Aminothiazol-4-yl) 2-(2-carboxyprl~mino)acetamido l-3-(l.-met Yl-tetrazol-5-ylthiomethyl~ceDh-3-em-4-carboxylic acid.
_ _ . . _~
The product of Stage a) (2.0g) in anisole (lOml) was stirred with trifluoroacetic acid (20ml) at 25-. After 2.5 h, the volatile solvent was removed in vacuo and the residue was partitioned between water and ethyl acetate.
~he aqueou~ phase was evaporated to give the title compound (920mg), [~D (DMSO)-58-, A (pH 6 buffer) 232 (inf) ( 17,860), 256nm (inf) ~ 16,280).
2g~73 PHARMACY EXAMPLES
.
EXAMPL~ A - Dr~ Powder for Ini~ction Formula Per Vial .
(6R,7R)-7-L(Z)-2-(2-aminothiazol-4-yl)-2-(2-carboxyprop-2-oxyimino)acetamido]-3-(1-mPthyltetrazol-5-ylthiomethyl) ceph-3-em-4-carboxylic acid 500mg Sodium Carbonate, anhydrous 113mg Method Blend the sterile cephalosporin antibiotic with sterile sodium carbonate under aseptic conditions, Fill aseptically into glass vials under a blanket of sterile nitrogen, Close the vials using rubber discs or plugs, held in position by aluminium overseals, thereby preventing gaseous exchange or ingress of micro-organisms, Reconstitute the product by dissolving in Water for Injections or other suitable sterile vehicle shortly before administration, EXAMPLE B - Dry Powder for Iniection _ Fill sterile (6R,7R)-7-~(Z)-2-(2-aminothiazol-4-yl)-2-(1-carboxycyclobut-1-oxyimino)acetamido]-3-(1-methyltetrazol-5-ylthiomethyl)ceph-3-em-4-carboxylic acid, disodium salt into glass vials such that each vial contains an amount equivalent to 500mg of the antibiotic acid, Carry out the filling aseptically under a blanket of sterile nitrogen, Close the vials using rubber discs or plugs, held in position by aluminium overseals, thereby preventing gaseous exchange or ingress of micro-organisms.
Reconstitute the product by dissolving in Water for Injections or other suitable sterile vehicle shortly before administration.
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the preparation of cephalosporin antibiotics of the general formula (I) (wherein Ra and Rb, which may be the same or different, each represent a C1-4 alkyl group or Ra and Rb together with the carbon atom to which they are attached form a C3-7 cycloalkylidene group, and Y represents a C-linked tetrazolyl group optionally substituted by a C1-4 alkyl group) and non-toxic salts and non-toxic metabolically labile esters thereof characterised in that (A) a compound of formula:
(II) (wherein Y is as defined above; B is > S ?O; R1 represents hydrogen or a carboxyl blocking group and the dotted line bridging the 2-, 3- and 4- positions indicates that the compound is a ceph-2-em or ceph-3-em compound) or salt or N-silyl derivative thereof is acylated with an acid of formula:
(III) (wherein Ra and Rb are as defined above; R2 represents a carboxyl blocking group; and R3 is an amino or protected amino group) or with an acylating agent corresponding thereto; or (B) a compound of formula:
(IV) (wherein Ra, Rb, R3, B and the dotted line are as defined above;
R4 and R4a may independently represent hydrogen or a carboxyl blocking group; and X is a halogen atom or an acyloxy group) or a salt thereof is reacted with a sulphur nucleophile serving to form a group of formula -CH2SY (wherein Y is as defined above) at the 3-position; whereafter, if necessary and/or desired in each instance, any of the following reactions, in any appropriate sequence, are carried out:-i) conversion of a .DELTA.2 -isomer into the desired .DELTA.3 -isomer, ii) reduction of a compound wherein B is > S?O to form a compound wherein B is >S, iii) conversion of a carboxyl group into a non-toxic salt or non-toxic metabolically labile ester function, and iv) removal of any carboxyl blocking and/or N-protecting groups.
(II) (wherein Y is as defined above; B is > S ?O; R1 represents hydrogen or a carboxyl blocking group and the dotted line bridging the 2-, 3- and 4- positions indicates that the compound is a ceph-2-em or ceph-3-em compound) or salt or N-silyl derivative thereof is acylated with an acid of formula:
(III) (wherein Ra and Rb are as defined above; R2 represents a carboxyl blocking group; and R3 is an amino or protected amino group) or with an acylating agent corresponding thereto; or (B) a compound of formula:
(IV) (wherein Ra, Rb, R3, B and the dotted line are as defined above;
R4 and R4a may independently represent hydrogen or a carboxyl blocking group; and X is a halogen atom or an acyloxy group) or a salt thereof is reacted with a sulphur nucleophile serving to form a group of formula -CH2SY (wherein Y is as defined above) at the 3-position; whereafter, if necessary and/or desired in each instance, any of the following reactions, in any appropriate sequence, are carried out:-i) conversion of a .DELTA.2 -isomer into the desired .DELTA.3 -isomer, ii) reduction of a compound wherein B is > S?O to form a compound wherein B is >S, iii) conversion of a carboxyl group into a non-toxic salt or non-toxic metabolically labile ester function, and iv) removal of any carboxyl blocking and/or N-protecting groups.
2. A process as claimed in claim 1 characterised in that there is employed a compound of formula (III) or (IV) in which at least one of Ra and Rb represents a methyl or ethyl group.
3. A process as claimed in claim 1 characterised in that there is employed a compound of formula (III) or (IV) in which Ra and Rb together with the carbon atom to which they are attached form a C3-5 cycloalkylidene group.
4. A process according to claim 1 characterised in that the starting materials Ra and Rb are both methyl groups and Y is l-methyltetrazol-5-yl.
5. A process for the preparation of (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2-(2-carboxyprop-2-oxyimino)acetamido]-3-(1-methyltetrazol-5-ylthiomethyl)ceph-3-em-4-carboxylic acid characterised in that diphenylmethyl (6R,7R)-7-amino-3-(1-methyltetrazol-5-ylthiomethyl)ceph-3-em-4-carboxylate is acylated with (Z)-2-(2-t-butoxycarbonylprop-2-oxyimino)-2-(2-tritylamino-thiazol-4-yl)acetic acid in the presence of l-hydroxybenzotriazole and dicyclohexylcarbodiimide, and the protective t-butyl, diphenylmethyl and trityl groups are then removed.
6. A process according to claim 1 characterised in that in the starting materials Ra and Rb together with the carbon atoms to which they are attached form a cyclobutylidene group and Y is l-methyltetrazol-5-yl.
7. A process for the preparation of (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2-(1-carboxycyclobut-1-oxyimino)acetamido]-3-(1-methyltetrazol-5-ylthiomethyl)ceph-3-em-4-carhoxylic acid characterised in that diphenylmethyl (6R,7R)-7-amino-3-(1-methyltetrazol-5-ylthiomethyl)ceph-3-em-4-carboxylate is acylated with (Z)-2-(1-t-butoxycarbonylcyclobut-1-oxyimino)-2-(2-tritylaminothiazol-4-yl)acetic acid in the presence of l-hydroxybenzotriazole and dicyclohexylcarbodiimide, and the protective t-butyl, diphenylmethyl and trityl groups are then removed.
8. A process as claimed in claim 1, 2 or 3 characterised in that one employs a ceph-3-em compound of formula (II) in which B is >S.
9. A process as claimed in claim 1, 2 or 3 characterised in that one acylates a compound of formula (II) with an acid halide corresponding to the acid of formula (III).
10. A process as claimed in claim 1, 2 or 3 characterised in that one employs a compound of formula (IV) wherein X is an acetoxy group or bromine atom.
11. A cephalosporin antibiotic of the general formula (I) defined in claim 1, and non-toxic salts, and non-toxic metabolically labile esters thereof, when prepared by the process of claim 1 or by an obvious chemical equivalent thereof.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB23041/78 | 1978-05-26 | ||
| GB2304278A GB1604724A (en) | 1978-05-26 | 1978-05-26 | 7-(2-aminothiazol-4-yl)-2-oxymino-acedamido)-cephem derivatives |
| GB23042/78 | 1978-05-26 | ||
| GB23041/78A GB1604723A (en) | 1978-05-26 | 1978-05-26 | 7-(2-aminothiazol-4-yl)-2-oxyimino-acetamido)-cephem derivatives |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1122973A true CA1122973A (en) | 1982-05-04 |
Family
ID=26256274
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA328,415A Expired CA1122973A (en) | 1978-05-26 | 1979-05-25 | Cephalosporin antibiotics |
Country Status (2)
| Country | Link |
|---|---|
| AT (1) | AT365600B (en) |
| CA (1) | CA1122973A (en) |
-
1979
- 1979-05-25 CA CA328,415A patent/CA1122973A/en not_active Expired
- 1979-05-25 AT AT0383779A patent/AT365600B/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| AT365600B (en) | 1982-01-25 |
| ATA383779A (en) | 1981-06-15 |
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| MKEX | Expiry |