Note: Descriptions are shown in the official language in which they were submitted.
~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
-- 2
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:~
-- 3
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
-- 4
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
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
NH2
=~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
-- 6
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,
73
- 10
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).
--11--
: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
- 13 -
_ . _ . . _ . _ _ . , . . _ .
Ra Rb Y
. __ . . . . __ . _ . _ . . __,
~) ,Alkyl groups
~ . .
~3 ~ C2H5 l.methyl-tetrazol-5-yl-
2 5
b~ Cycloalkylidene groups
__ . __ .
cyclopropylidene l-methyl-tetrazol-5-yl
cyc lopentylidene . . . _ . ._
~lZ2973
14
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
R3
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
R3
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
- 16 -
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,
973
- 17 -
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~
19
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
21
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
- 22 -
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
73
- 23
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
R3
~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
R3
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
1122973
26
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
27
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
28
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
- 30
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
- 31
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
- 32
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
- 33
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
- 34 -
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
36-
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
- 38 -
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
1122973
- 39 -
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.
