The invention relates to novel compounds of high antimicrobial activity of the formula: ##STR1## wherein R.sup.1 is amino or protected amino, PA0 R.sup.2 is carboxy(lower)alkyl or protected carboxy(lower)alkyl, and PA0 R.sup.3 is carboxy or protected carboxy, and a pharmaceutically acceptable salt thereof.

The present invention relates to new cephem compounds and pharmaceutically 
acceptable salts thereof. More particularly, it relates to new cephem 
compounds and pharmaceutically acceptable salts thereof, which have 
antimicrobial activities, to processes for preparation thereof, to 
pharmaceutical composition comprising the same, and to a method of using 
the same therapeutically in the treatment of infectious diseases in human 
being and animals. 
Accordingly, it is one object of the present invention to provide new 
cephem compounds and pharmaceutically acceptable salts thereof, which are 
active against a number of pathogenic microorganisms, especially for oral 
administration. 
Another object of the present invention is to provide processes for the 
preparation of new cephem compounds and pharmaceutically acceptable salts 
thereof. 
A further object of the present invention is to provide pharmaceutical 
composition comprising, as active ingredients, said new cephem compounds 
and pharmaceutically acceptable salts thereof. 
Still further object of the present invention is to provide a method for 
the treatment of infectious diseases cuased by pathogenic bacteria in 
human being and animals. 
The object new cephem compounds are novel and can be represented by the 
following general formula: 
##STR2## 
wherein R.sup.1 is amino or protected amino, 
R.sup.2 is carboxy(lower)alkyl or protected carboxy(lower)alkyl, and 
R.sup.3 is carboxy or protected carboxy. 
According to the present invention, the new cephem compounds (I) can be 
prepared by various processes which are illustrated in the following 
schemes. 
##STR3## 
wherein R.sup.1, R.sup.2 and R.sup.3 are each as defined above, 
R.sub.a.sup.2 is protected carboxy(lower)alkyl, and 
R.sub.b.sup.2 is carboxy(lower)alkyl. 
Regarding the object compounds (I) and (Ib) and the starting compounds (Ia) 
and (III), it is to be understood that said object and starting compounds 
include syn isomer, anti isomer and a mixture thereof. For example, with 
regard to the object compound (I), syn isomer means one geometrical isomer 
having the partial structure represented by the following formula: 
##STR4## 
(wherein R.sup.1 and R.sup.2 are each as defined above) and anti isomer 
means the other geometrical isomer having the partial structure 
represented by the following formula: 
##STR5## 
(wherein R.sup.1 and R.sup.2 are each as defined above). 
Suitable pharmaceutically acceptable salts of the object compounds (I) are 
conventional non-toxic salt and include a metal salt such as an alkali 
metal salt (e.g. sodium salt, potassium salt, etc.) and an alkaline earth 
metal salt (e.g. calcium salt, magnesium salt, etc.), an ammonium salt, an 
organic base salt (e.g. trimethylamine salt, triethylamine salt, pyridine 
salt, picoline salt, dicyclohexylamine salt, N,N'-dibenzylethylenediamine 
salt, etc.), an organic acid salt (e.g. acetate, maleate, tartrate, 
methanesulfonate, benzenesulfonate, formate, toluenesulfonate, etc.), an 
inorganic acid salt (e.g. hydrochloride, hydrobromide, sulfate, phosphate, 
etc.), or a salt with an amino acid (e.g. orginine, aspartic acid, 
glutamic acid, etc.), and the like. 
In the above and subsequent descriptions of the present specification, 
suitable examples and illustrations of the various definitions which the 
present invention include within the scope thereof are explained in 
details as follows. 
The term "lower" is intended to mean 1 to 6 carbon atoms, unless otherwise 
indicated. 
Suitable "protected amino" may include an acylamino or an amino group 
substituted by a conventional protecting group such as ar(lower)alkyl 
which may have at least one suitable substituent(s), (e.g. benzyl, trityl, 
etc.) or the like. 
Suitable acyl moiety in the term "acylamino" may include aliphatic acyl 
group and acyl group containing an aromatic or heterocyclic ring. And, 
suitable examples of the said acyl may be 
lower alkanoyl (e.g. formyl, acetyl, propionyl, butyryl, isobutyryl, 
valeryl, isovaleryl, oxalyl, succinyl, pivaloyl, etc.); 
lower alkoxycarbonyl (e.g. methoxycarbonyl, ethoxycarbonyl, 
propoxycarbonyl, 1-cyclopropylethoxycarbonyl, isopropoxycarbonyl, 
butoxycarbonyl, tert-butoxycarbonyl, pentyloxycarbonyl, hexyloxycarbonyl, 
etc.); 
lower alkanesulfonyl (e.g. mesyl, ethanesulfonyl, propanesulfonyl, 
isopropanesulfonyl, butanesulfonyl, etc.); 
arenesulfonyl (e.g. benzenesulfonyl, tosyl, etc.); 
aroyl (e.g. benzoyl, toluoyl, xyloyl, naphthoyl, phthaloyl, indancarbonyl, 
etc.); 
ar(lower)alkanoyl (e.g. phenylacetyl, phenylpropionyl, etc.); 
ar(lower)alkoxycarbonyl (e.g. benzyloxycarbonyl, phenethyloxycarbonyl, 
etc.), and the like. 
The acyl moiety as stated above may have at least one suitable 
substituent(s) such as halogen (chlorine, bromine, fluorine and iodine) or 
the like. 
Suitable "protected carboxy" and "protected carboxy moiety" in the term 
"protected carboxy(lower)alkyl" may include an esterified carboxy and the 
like, and suitable examples of the ester moiety in said esterified carboxy 
may be the ones such as lower alkyl ester (e.g. methyl ester, ethyl ester, 
propyl ester, isopropyl ester, butyl ester, isobutyl ester, tert-butyl 
ester, pentyl ester, hexyl ester, 1-cyclopropylethyl ester, etc.) which 
may have at least one suitable substituent(s), for example, 
lower alkanoyloxy(lower)alkyl ester (e.g. acetoxymethyl ester, 
propionyloxymethyl ester, butyryloxymethyl ester, valeryloxymethyl ester, 
pivaloyloxymethyl ester, 2-acetoxyethyl ester, 2-propionyloxyethyl ester, 
hexanoyloxymethyl ester, etc.), lower alkanesulfonyl(lower)alkyl ester 
(e.g. 2-mesylethyl ester, etc.) or mono(or di or tri)-halo(lower)alkyl 
ester (e.g. 2-iodoethyl ester, 2,2,2-trichloroethyl ester, etc.); lower 
alkenyl ester (e.g. vinyl ester, allyl ester, etc.); 
lower alkynyl ester (e.g. etynyl ester, propynyl ester, etc.); 
ar(lower)alkyl ester which may have at least one suitable substituent(s) 
(e.g. benzyl ester, 4-methoxybenzyl ester, 4-nitrobenzyl ester, phenethyl 
ester, trityl ester, diphenylmethyl ester,bis(methoxyphenyl)methyl ester, 
3,4-dimethoxybenzyl ester, 4-hydroxy-3,5-di-tert-butylbenzyl ester, etc.); 
aryl ester which may have at least one suitable substituent(s) (e.g. phenyl 
ester, 4-chlorophenyl ester, tolyl ester, tert-butylphenyl ester, xylyl 
ester, mesityl ester, cumenyl ester, etc.), and the like. 
Preferable example of the esterified carboxy as mentioned above may include 
lower alkoxycarbonyl (e.g. methoxycarbonyl, ethoxycarbonyl, 
propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, 
tert-butoxycarbonyl, pentyloxycarbonyl, tert-pentyloxycarbonyl, 
hexyloxycarbonyl, 1-cyclopropylethoxycarbonyl, etc.). 
Suitable "lower alkyl moiety" in the terms "carboxy(lower)alkyl" and 
"protected carboxy(lower)alkyl" may include methyl, ethyl, propyl, 
isopropyl, butyl, t-butyl, pentyl, hexyl and the like. 
Preferable example of carboxy(lower)alkyl may include carboxymethyl, 
1-carboxyethyl, 2-carboxyethyl, 1-carboxypropyl, 2-carboxypropyl, 
3-carboxypropyl, 4-carboxybutyl, 5-carboxypentyl, 6-carboxyhexyl, 
1-carboxyisopropyl, 1-ethyl-1-carboxyethyl, 2-methyl-2-carboxypropyl, and 
the like. 
Preferable example of protected carboxy(lower)alkyl may include esterified 
carboxy(lower)alkyl, and more preferably lower alkoxycarbonyl(lower)alkyl 
(e.g. methoxycarbonylmethyl, ethoxycarbonylmethyl, propoxycarbonylmethyl, 
tert-butoxycarbonylmethyl, 2-ethoxycarbonylethyl, 2-ethoxycarbonylpropyl, 
4-ethoxycarbonylbutyl, 1-tert-butoxycarbonylisopropyl, 
1-tert-butoxycarbonyl-1-methylpropyl, 4-tert-butoxycarbonylbutyl, 
5-tert-butoxycarbonylpentyl, 6-butoxycarbonylhexyl, etc.) and the like. 
The processes for preparing the object compounds of the present invention 
are explained in details in the following. 
PROCESS 1 
The object compound (I) or a salt thereof can be prepared by reacting the 
compound (II) or its reactive derivative at the amino group or a salt 
thereof with the compound (III) or its reactive derivative at the carboxy 
group or a salt thereof. 
Suitable reactive derivative at the amino group of the compound (II) may 
include Schiff's base type imino or its tautomeric enamine type isomer 
formed by the reaction of the compound (II) with a carbonyl compound such 
as aldehyde, ketone or the like; a silyl derivative formed by the reaction 
of the compound (II) with a silyl compound such as 
bis(trimethylsilyl)acetamide, trimethylsilylacetamide or the like; a 
derivative formed by reaction of the compound (II) with phosphorus 
trichloride or phosgene, and the like. 
Suitable salt of the compounds (II) and (III) may include an acid addition 
salt such as an organic acid salt (e.g. acetate, maleate, tartrate, 
benzenesulfonate, toluenesulfonate, etc.) or an inorganic acid salt (e.g. 
hydrochloride, hydrobromide, sulfate, phosphate, etc.); a metal salt (e.g. 
sodium salt, potassium salt, calcium salt, magnesium salt, etc.); ammonium 
salt; an organic amine salt (e.g. triethylamine salt, dicyclohexylamine 
salt, etc.), and the like. 
Suitable reactive derivative at the carboxy group of the compound (III) may 
include an acid halide, an acid anhydride, an activated amide, an 
activated ester, and the like. The suitable example may be an acid 
chloride, an acid azide; a mixed acid anhydride with an acid such as 
substituted phosphoric acid (e.g. dialkylphosphoric acid, phenylphosphoric 
acid, diphenylphosphoric acid, dibenzylphosphoric acid, halogenated 
phosphoric acid, etc.), dialkylphosphorous acid, sulfurous acid, 
thiosulfuric acid, sulfuric acid, alkylcarbonic acid, aliphatic carboxylic 
acid (e.g. pivalic acid, pentanoic acid, isopentanoic acid, 2-ethylbutyric 
acid or trichloroacetic acid, etc.) or aromatic carboxylic acid (e.g. 
benzoic acid, etc.); a symmetrical acid anhydride; an activated amide with 
imidazole, 4-substituted imidazole, dimethylpyrazole, triazole or 
tetrazole; or an activated ester (e.g. cyanomethyl ester, methoxymethyl 
ester, dimethyliminomethyl [(CH.sub.3).sub.2 N.sup.+ .dbd.CH--]ester, 
vinyl ester, propargyl ester, p-nitrophenyl ester, 2,4-dinitrophenyl 
ester, trichlorophenyl ester, pentachlorophenyl ester, mesyl phenyl ester, 
phenylazophenyl ester, phenyl thioester, p-nitrophenyl thioester, p-cresyl 
thioester, carboxymethyl thioester, pyranyl ester, pyridyl ester, 
piperidyl ester, 8-quinolyl thioester, etc.), or an ester with a N-hydroxy 
compound (e.g. N,N-dimethylhydroxylamine, 1-hydroxy-2-(1H)-pyridone, 
N-hydroxysuccinimide, N-hydroxyphthalimide, 1-hydroxy-6 
-chloro-1H-benzotriazole, etc.), and the like. These reactive derivatives 
can optionally be selected from them according to the kind of the compound 
(III) to be used. 
The reaction is usually carried out in a conventional solvent such as 
water, acetone, dioxane, acetonitrile, chloroform, methylene chloride, 
ethylene chloride, tetrahydrofuran, ethyl acetate, N,N-dimethylformamide, 
pyridine or any other organic solvents which do not adversely influence 
the reaction. These conventional solvents may also be used in a mixture 
with water. 
When the compound (III) is used in free acid form or its salt form in the 
reaction, the reaction is preferably carried out in the presence of a 
conventional condensing agent such as N,N'-dicyclohexylcarbodiimide; 
N-cyclohexyl-N'-morpholinoethylcarbodiimide; 
N-cyclohexyl-N'-(4-diethylaminocyclohexyl)carbodiimide; 
N,N'-diethylcarbodiimide; N,N'-diisopropylcarbodiimide; 
N-ethyl-N'-(3-dimethylaminopropyl)carbodiimide; 
N,N-carbonylbis-(2-methylimidazole); 
pentamethyleneketene-N-cyclohexylimine; diphenylketene-N-cyclohexylimine; 
ethoxyacetylene; 1-alkoxy-1-chloroethylene; trialkyl phosphite; ethyl 
polyphosphate; isopropyl polyphosphate; phosphorus oxychloride (phosphoryl 
chloride); phosphorus trichloride; thionyl chloride; oxalyl chloride; 
triphenylphosphine; 2-ethyl-7-hydroxybenzisoxazolium salt; 
2-ethyl-5-(m-sulfophenyl)isoxazolium hydroxide intra-molecular salt; 
1-(p-chlorobenzenesulfonyloxy)-6-chloro-1H-benzotriazole; so-called 
Vilsmeier reagent prepared by the reaction of dimethylformamide with 
thionyl chloride, phosgene, phosphorus oxychloride, etc.; or the like. 
The reaction may also be carried out in the presence of an inorganic or 
organic base such as an alkali metal bicarbonate, tri(lower)alkylamine, 
pyridine, N-(lower)-alkylmorphorine, N,N-di(lower)alkylbenzylamine, or the 
like. The reaction temperature is not critical, and the reaction is 
usually carried out under cooling or at ambient temperature. 
PROCESS 2 
The object compound (Ib) or a salt thereof can be prepared by subjecting 
the compound (Ia) or a salt thereof to elimination reaction of the carboxy 
protective group on R.sub.a.sup.2. 
Suitable salts of the compounds (Ia) and (Ib) can be referred to the one 
exemplified for the compound (I). 
In the present elimination reaction, all conventional methods used in the 
elimination reaction of the carboxy protective group, for example, 
hydrolysis, elimination using Lewis acid, etc. are applicable. When the 
carboxy protective group is an ester, it can be eliminated by hydrolysis 
or elimination using Lewis acid. The hydrolysis is preferably carried out 
in the presence of a base or an acid. Suitable base may include an 
inorganic base and an organic base as aforementioned. 
Suitable acid may include an organic acid (e.g. formic acid, acetic acid, 
propionic acid, etc.) and an inorganic acid (e.g. hydrochloric acid, 
hydrobromic acid, sulfuric acid, etc.). 
The present hydrolysis is usually carried out in an organic solvent, water 
or a mixed solvent thereof. 
The reaction temperature is not critical, and it may suitably be selected 
in accordance with the kind of the carboxy protective group and the 
elimination method. 
The elimination using Lewis acid is preferable to eliminate substituted or 
unsabstituted ar(lower)alkyl ester or lower alkyl ester and carried out by 
reacting the compound (Ia) or a salt thereof with Lewis acid such as boron 
trihalide (e.g. boron trichloride, boron trifluoride, etc.), titanium 
tetrahalide (e.g. titanium tetrachloride, titanium tetrabromide, etc.), 
tin tetrahalide (e.g. tin tetrachloride, tin tetrabromide etc.), aluminum 
halide (e.g. aluminum chloride, aluminum bromide, etc.), trihaloacetic 
acid (e.g. trichloroacetic acid, trifluoroacetic acid, etc.) or the like. 
This elimination reaction is preferably carried out in the presence of 
cation trapping agents (e.g. anisole, phenol, etc.) and is usually carried 
out in a solvent such as nitroalkane (e.g. nitromethane, nitroethane, 
etc.), alkylene halide (e.g. methylene chloride, ethylene chloride, etc.), 
diethyl ether, carbon disulfide or any other solvent which does not 
adversely affect the reaction. A liquid acid can also be used as the 
solvent. These solvents may be used as a mixture thereof. The reaction 
temperature is not critical, and the reaction is usually carried out under 
cooling, at ambient temperature or under warming. 
In case that the object compound (I) is obtained in a form of the free acid 
at the 4-position and/or the oxime portion and/or in case that the object 
compound (I) has free amino group, it may be transformed into its 
pharmaceutically acceptable salt as aforementioned by a conventional 
method. 
The object compounds (I) and pharmaceutically acceptable salts thereof of 
the present invention are novel compounds which exhibit high antibacterial 
activity and inhibit the growth of a wide variety of pathogenic 
microorganisms including Gram-positive and Gram-negative bacteria and are 
useful as antimicrobial agents, especially for oral administration. For 
therapeutic purpose, the compounds according to the present invention can 
be used in the form of conventional pharmaceutical preparation which 
contain said compounds, as an active ingredient, in admixture with a 
pharmaceutically acceptable carrier such as an organic or an inorganic 
solid or liquid excipient suitable for oral, parenteral or external 
administration. The pharmaceutical preparations may be in solid form such 
as capsule, tablet, dragee, ointment or suppository, or in liquid form 
such as solution, suspension, or emulsion. If desired, there may be 
included in the above preparations auxiliary substances, stabilizing 
agents, wetting or emulsifying agents, buffers and other commonly used 
additives, such as lactose, fumaric acid, citric acid, tartaric acid, 
stearic acid, maleic acid, succinic acid, malic acid, magnesium stearate, 
terra alba, sucrose, corn starch, talc, gelatin, agar, pectin, peanut oil, 
olive oil, cacao butter, ethylene glycol and the like. 
While the dosage of the compounds will vary depending upon the age and 
condition of the patient, an average single dose of about 10 mg, 50 mg, 
100 mg, 250 mg, 500 mg, and 1000 mg of the compounds according to the 
present invention was proved to be effective for treating infectious 
diseases caused by pathogenic bacteria. In general, amounts between 1 
mg/body and about 6,000 mg/body or even more may be administered per day. 
In order to illustrate the usefulness of the object compound, 
anti-microbial activities, urinary excretion and biliary excretion of a 
representative compound of the present invention are shown below. 
[1] Test Compound: 
7-[2-Carboxymethoxyimino-2-(5-amino-1,2,4-thiadiazol-3-yl)acetamido]-3-azid 
omethyl-3-cephem-4-carboxylic acid (syn isomer). 
(hereinafter referred to as Test Compound (1)) 
[2] Test: 
(A) Minimal inhibitory concentration 1 Test Method 
In vitro antibacterial activity was determined by the two-fold agar-plate 
dilution method as described below. 
One loopful of an overnight culture of each test strain in Trypticase-soy 
broth (10.sup.8 viable cells per ml) was streaked on heart infusion agar 
(HI-agar) containing graded concentrations of representative test 
compound, and the minimal inhibitory concentration (MIC) was expressed in 
tems of .mu.g/ml after incubation at 37.degree. C. for 20 hours. 
2 Test Results 
______________________________________ 
MIC (.mu.g/ml) 
Compound 
Test strains Test Compound (1) 
______________________________________ 
Proteus mirabilis 18 
0.05 
Proteus vulgaris 2 
0.1 
______________________________________ 
(B) Urinary excretion 
1 Test Method 
Urine of rats was collected with a urine collector at 0 to 6, and 6 to 24 
hours after oral administration of 100 mg/kg of the test antibiotic. The 
antibiotic levels in the urine samples were bioassayed with the standard 
solution prepared with M/15 phosphate buffer (pH 7.0) and the urinary 
recovery in 24 hours was calculated. 
2 Test Result 
______________________________________ 
Urinary recovery in 
24 hours (%) 
______________________________________ 
Test Compound (1) 
26.61 
______________________________________ 
(C) Biliary excretion 
1 Test Method 
Rats anesthetized with pentobarbital were fixed in supine position, and a 
polyethylene cannula was inserted into the bile duct. Bile samples were 
collected at 0 to 3, 3 to 6, and 6 to 24 hours after oral administration 
of 100 mg/kg of the test antibiotic. The antibiotic levels in the bile 
samples were bioassayed with the standard solutions prepared with M/15 
phosphate buffer (pH 7.0) and the biliary recovery in 24 hours were 
calculated. 
2 Test Result 
______________________________________ 
Biliary recovery in 
24 hours (%) 
______________________________________ 
Test Compound (1) 
4.72 
______________________________________ 
The following examples are given for the purpose of illustrating the 
present invention in more detail.