The compounds of this invention are cephalosporins having various acyl substituents at the 7-position and a carboxyalkyl or carbamoylalkyl substituted oxadiazolylthiomethyl group at the 3-position of the cephem nucleus and intermediates for the preparation thereof. The 7-acylated compounds have antibacterial activity.

This invention relates to a new series of cephalosporin compounds which 
have antibacterial activity when administered parenterally and orally and 
to intermediates for the preparation thereof. In particular, the 
structures of the biologically active cephalosporin compounds of this 
invention are characterized by having a carboxyalkyl or carbamoylalkyl 
substituted oxadiazolylthiomethyl group at the 3-position of the cephem 
nucleus. Also, this invention extends to methods and compositions for 
treating certain bacterial infections using these new compounds as well as 
to certain chemical intermediates and methods for preparing the compounds 
described hereafter. 
The compounds of this invention are represented by the following structural 
formula: 
##STR1## 
in which: R.sup.1 is an acyl group selected from the group consisting of: 
##STR2## 
where: X is thienyl; dihydrophenyl; phenyl or phenyl monosubstituted with 
hydroxy, hydroxymethyl, formamido, ureido or carboxymethylamino; 
A is NH.sub.2, OH, COOH or SO.sub.3 H; or formyloxy when X i phenyl; 
Y is cyano, aminomethylphenyl, sydnone, pyridone, thienyl or tetrazolyl; 
Z is methyl, trifluoromethyl, trifluoroethyl, pyridyl or cyanomethyl; 
m is 0 to 2; 
n is 1 to 5; and 
R.sup.2 is hydroxy, amino, lower alkylamino or di(lower)alkylamino, 
Or a non-toxic pharmaceutically acceptable salt thereof. 
As used herein, the term "lower alkyl" refers to groups containing from 1 
to 4 carbon atoms. 
It will be recognized that the 4-carboxylic acid group of the compounds of 
Formula I may be readily esterified by methods well known to the art. 
These esters include, for example, simple alkyl and aryl esters as well as 
esters which are easily cleaved, within the body, to the parent acid such 
as indanyl, pivaloyloxymethyl, acetoxymethyl, propionyloxymethyl, 
glycyloxymethyl, phenylglycyloxymethyl and thienylglycyloxymethyl esters 
and others. Of course, when A is COOH, this group may be similarly 
esterified. All such esters are included within the scope of this 
invention. 
A particular group of compounds of this invention is represented by Formula 
I where n is 1 and R.sup.2 is hydroxy. 
Another group of compounds of this invention is represented by Formula I 
where n is 1, R.sup.2 is hydroxy and 
##STR3## 
A more particular group of compounds is that represented by Formula I where 
n is 1, R.sup.2 is hydroxy, 
##STR4## 
Examples of some 7-acyl substituents (R.sup.1 -NH--) of the compounds of 
Formula I are listed below: 
.alpha.-hydroxyphenylacetamido 
.alpha.-aminophenylacetamido 
.alpha.-amino-4-hydroxyphenylacetamido 
trifluoromethylthioacetamido 
methylthioacetamido 
2,2,2-trifluoroethylsulfinylacetamido 
cyanoacetamido 
.alpha.-carboxythienylacetamido 
.alpha.-carboxyphenylacetamido 
.alpha.-sulfophenylacetamido 
methylsulfonylacetamido 
cyanomethylthioacetamido 
.alpha.-amino-4-carboxymethylaminophenylacetamido 
2-aminomethylphenylacetamido 
3-sydnoneacetamido 
1-tetrazolylacetamido 
2-thienylacetamido 
2-pyridoneacetamido 
4-pyridoneacetamido 
4-pyridylthioacetamido. 
An example of the compounds of this invention is the compound 
7-D-mandelamido-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephe 
m-4-carboxylic acid. 
Cephalosporin derivatives having the 7-acyl substituents defined above are 
all documented in the prior art. Substitution by a substituted 
S-heterocyclicthiomethyl group (--CH.sub.2 SHet) where Het includes 
oxadiazolyl at the 3-position of the cephem nucleus is also known and is 
generically disclosed in Belgian Pat. No. 814,546 where the heterocyclic 
ring also may be substituted by, among others, carboxy; in Belgian Pat. 
Nos. 808,906 and 818,209 where the heterocyclic ring is substituted by, 
among others, carboxyalkyl; in U.S. Pat. No. 3,819,623, Netherlands Pat. 
No. 6916131, Belgian Pat. No. 827,600 and German Offenlegungschrift 
2,445,071 where the heterocyclic ring is substituted by, inter alia, 
carboxy and carboxyalkyl; in U.S. Pat. No. 3,883,520 where the 
heterocyclic ring is substituted by, among others, carboxy and 
carboxamido; in Belgian Pat. No. 823,861 where the heterocyclic ring is 
substituted by, inter alia, carboxy, carboxyalkyl, carbamoyl and 
carbamoylalkyl; and in Japanese Pat. No. 7,205,550 where the heterocyclic 
ring is substituted by --(CH.sub.2).sub.n R.sup.3 where n is 0 to 3 and 
R.sup.3 includes carboxy and N-alkoxyalkylcarbamoyl. No specific example 
of any cephalosporin containing a 3-oxadiazolylthiomethyl group 
substituted by carboxy, carboxyalkyl, carbamoyl or carbamoylalkyl, 
especially with the 7-acyl groups here disclosed, is believed to be known 
in the art. 
The compounds of Formula I are preferably prepared by acylating 
7-aminocephalosporanic acid (7-ACA) with an appropriate acylating agent, 
suitably protected as necessary, and then displacing the 3-acetoxy group 
with the desired substituted oxadiazole thiol of the formula: 
##STR5## 
in which: n is 1 to 5; and 
R.sup.2 is hydroxy, amino, lower alkylamino or di(lower)alkylamino, 
with subsequent removal of the protective group(s). When certain acylating 
agents are used, for example activated and protected derivatives of 
mandelic acid, it is preferable to remove the protecting group from the 
7-sidechain prior to displacement. 
The carboxylic acid group of the acylating agent in the first step of this 
reaction, the 7-acylation, is activated by any of the standard methods 
known to the art such as conversion to the mixed anhydride, acid chloride, 
acid imidazolide or activated ester. In addition, a reagent such as 
dicyclohexylcarbodiimide can be used provided that the carboxyl group on 
the cephem nucleus is protected with an easily removable protecting group 
such as a benzhydryl, t-butyl, trichloroethyl, benzyl, benzyloxymethyl, 
p-methoxybenzyl or p-nitrobenzyl ester. When A is NH.sub.2, the 
.alpha.-amino group of the acylating agent is, preferably, protected prior 
to acylation with an easily removable protective group known in the art 
such as t-butoxycarbonyl, trichloroethoxycarbonyl, benzyloxycarbonyl, the 
methyl acetoacetate adduct or similar groups commonly used in the 
synthesis of peptides. 
Alternatively, the compounds of Formula I are prepared by acylation, as 
described above, of an appropriate 7-amino-3-(carboxyalkyl or 
carbamoylalkyl substituted oxadiazolylthiomethyl) cephalosporin nucleus of 
Formula III: 
##STR6## 
in which: n is 1 to 5; 
R.sup.2 is hydroxy, amino, lower alkylamino or di(lower)alkylamino; and 
R.sup.3 is hydrogen or a protecting ester group, 
with an appropriate acylating agent followed by removal of the protective 
groups when present. 
The protective groups can be removed according to methods well known to the 
art, such as with trifluoroacetic acid when t-butyl or t-butoxycarbonyl 
protective groups are used. The resulting salt is converted to the 
zwitterionic product or to the free acid by means of a basic ion exchange 
resin such as polystyreneamine ion exchange resin (Amberlite IR-45) or 
else by basification of an aqueous solution of the salt. 
The acylating agents used as starting materials are either known or 
prepared by known methods. 
The 7-amino-3-(carboxyalkyl and carbamoylalkyl substituted 
oxadiazolylthiomethyl) cephalosporin starting materials of Formula III are 
prepared by reaction of 7-aminocephalosporanic acid and a substituted 
oxadiazole thiol of Formula II and then esterifying. 
The carboxyalkyl substituted oxadiazole thiols of Formula II are prepared 
from reaction of a dithiocarbazic acid salt, prepared from hydrazine and 
carbon disulfide in the presence of a base such as potassium hydroxide, 
with a carbalkoxyalkanoic acid halide, preferably chloride, for example 
ethyl malonyl chloride, followed by thermal cyclization to give a 
2-carbalkoxyalkyl-1,3,4-oxadiazole-5-thiol with subsequent hydrolysis of 
the ester function. 
The carbamoylalkyl substituted oxadiazole thiols of Formula II are prepared 
by treatment of a 2-carbalkoxyalkyl-1,3,4-oxadiazole-5-thiol with ammonia 
when R.sup.2 is amino or with an alkyl-or dialkylamine when R.sup.2 is 
lower alkylamino or di(lower)alkylamino, respectively. 
Certain compounds of this invention are capable of forming salts at any 
acidic or basic groups present with, for example, the alkali metals such 
as sodium or potassium, the alkaline earth metals such as calcium or with 
the ammonium cation. When A is NH.sub.2, the compounds can exist as the 
zwitterion or as either an acid or base salt. These salts are prepared by 
standard methods using a wide variety of non-toxic pharmaceutically 
acceptable acids and bases known in the art and are also considered as 
objects of this invention. 
It will be recognized that due to the asymmetric .alpha.-carbon atom in the 
7-acetamido group of Formula I when 
##STR7## 
optical isomers will exist. Racemic or resolved products are obtained 
depending upon whether a racemic or resolved sidechain acid is used as an 
acylating agent. The resolved side-chain acids are readily obtained from 
the racemic compounds by resolution according to well known methods, 
including fractional crystallization of a salt formed with an optically 
active acid or base. All of the isomers, including separated isomers and 
mixtures thereof, are included within the scope of this invention. 
The compounds of Formula I have exceptional antibacterial activity against 
both Gram-positive and Gram-negative organisms. Minimum inhibitory 
concentrations (MIC's) range from 0.2 to &gt;200 .mu.g./ml. in in vitro 
testing. Test results for the compound 
7-D-mandelamido-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephe 
m-4-carboxylic acid and its disodium salt, respectively, are given below: 
______________________________________ 
Bacteria MIC (.mu.g./ml.) 
______________________________________ 
S. aureus HH 125 1.6, 3.1 
S. aureus SK 23390 0.4, 0.8 
S. villaluz SK 70390 
50, 200 
Strep. faecalis HH 34358 
12.5, 50 
E. coli SK 12140 0.8, 0.8 
E. coli HH 33779 1.6, 3.1 
Kleb. pneumo. SK 4200 
0.8, 0.8 
Kleb. pneumo. SK 1200 
0.8, 0.4 
Salmonella ATCC 12176 
0.8, 0.8 
Shigella HH 117 0.2, 0.4 
Pseudo. aerug. HH 63 
&gt;200, &gt;200 
Serratia marc. ATCC 13880 
25, 50 
Proteus morgani 179 6.3, 6.3 
Entero. aerog. ATCC 13048 
3.1, 3.1 
Entero. cloacae HH 31254 
1.6, 1.6 
______________________________________ 
In the in vivo mouse protection test, 
7-D-mandelamido-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephe 
m-4-carboxylic acid exhibited ED.sub.50 's of 1.56 mg./kg. against E. coli 
12140 and 0.86 mg./kg. against Kleb. pneumo. 4200 upon subcutaneous 
injection. 
Pharmaceutical compositions having antibacterial activity which comprise a 
pharmaceutical carrier containing an active but non-toxic quantity of a 
compound of Formula I as well as methods of combatting bacterial 
infections by administering such a composition to an infected host in a 
non-toxic amount sufficient to combat such infections are also objects of 
this invention. The administration may be orally or by parenteral 
injection such as subcutaneously, intramuscularly or intravenously. The 
injection of suitably prepared sterile solutions or suspensions containing 
an effective, non-toxic amount of the new cephalosporin compound is the 
preferred route of administration. 
The compounds of Formula I are formulated and administered in the same 
manner as other cephalosporins. The dosage regimen comprises 
administration, preferably by injection, of an active but non-toxic 
quantity of a compound of Formula I selected from the dosage unit range of 
from 100 to 1000 mg. with the total daily dosage regimen being from 400 
mg. to 6 g. The precise dosages are dependent upon the age and weight of 
the subject and on the infection being treated and can be determined by 
those skilled in the art based on the data disclosed herein compared with 
that available to the art attained with known cephalosporins. 
The following examples illustrate the invention but are not to be construed 
as limiting the scope thereof. Temperatures are in degrees Centigrade 
(.degree.C.) unless otherwise stated.

EXAMPLE 1 
7-D-Mandelamido-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephem 
-4-carboxylic acid 
Carbon disulfide (152 g, 2.0 mol) was added dropwise to a cooled (ca. 
15.degree.) solution of 130 g (2.0 mol) of potassium hydroxide (85%) and 
64 g (2.0 mol) of hydrazine (95%) in 1000 ml of ethanol and the mixture 
was stirred for 1 hour in the cold. The solid which formed was collected 
and recrystallized from water-methanol-ethanol to give dithiocarbazic acid 
potassium salt, m.p. 78.degree.-90.degree. C (dec.). 
A solution of 44.4 g (0.296 mol) of ethyl malonyl chloride in 80 ml of 
tetrahydrofuran and a solution of 29.6 g (0.296 mol) of potassium 
bicarbonate in 100 ml of water were added simultaneously over a 45 minute 
interval to a solution of 43.2 g (0.296 mol) of dithiocarbazic acid 
potassium salt in 200 ml of tetrahydrofuran and 200 ml of water at 
5.degree.. The reaction mixture was stirred at 5.degree. for 1 hour then 
at ambient temperature for 12 hours. The solvents were evaporated and the 
residue was taken up into 350 ml of ethanol and refluxed on a steam bath 
for 1.5 hours. The mixture was evaporated to dryness, 300 ml of ethyl 
acetate and 175 ml of water were added to the residue and it was acidified 
to pH 2.3 by addition of 3N hydrochloric acid. The layers were separated 
and the aqueous phase was extracted twice more with 250 ml portions of 
ethyl acetate. The combined organic extracts were dried (MgSO.sub.4), then 
the solvent was evaporated to give a residue which was dissolved in 
methylene chloride. The methylene chloride solution was filtered and the 
filtrate was evaporated to dryness. The residue was chromatographed on 
silica gel with 98:2:3 chloroform-ethanol-formic acid as eluant to give 
2-carbethoxymethyl-1,3,4-oxadiazole-5-thiol as a viscous oil. 
C.sub.6 H.sub.8 N.sub.2 O.sub.3 S. Calculated: 38.29%, C; 4.28%, H; 14.88% 
N. Found: 38.18%, C; 4.40%, H; 14.61% N. 
A solution of 3.15 g (0.017 mol) of 
2-carbethoxymethyl-1,3,4-oxadiazole-5-thiol in 25 ml of water and 25 ml of 
ethanol was stirred for 5 hours while maintaining the pH at 10-11 by 
addition of 10% aqueous sodium hydroxide solution. The mixture was 
neutralized to pH 7.0 then evaporated to dryness. The residue was 
dissolved in 15 ml of water, 50 ml of ethyl acetate was added and the 
solution was acidified to pH 1.5 with 3N hydrochloric acid. The layers 
were separated and the aqueous phase was extracted twice with ethyl 
acetate. The combined extracts were dried (Na.sub.2 SO.sub.4) and the 
solvent was evaporated to give a residue which was recrystallized from 
ether-cyclohexane to give 2-carboxymethyl-1,3,4-oxadiazole-5-thiol, m.p. 
167.degree. -169.degree. (dec.) 
C.sub.4 H.sub.4 N.sub.2 O.sub.3 S. Calculated: 29.99%, C; 2.52%, H; 17.49% 
N. Found: 30.58%, C; 2.90%, H; 17.46%, N. 
A solution of 1.25 g (7.82 mmol) of 
2-carboxymethyl-1,3,4-oxadiazole-5-thiol, 3.00 g 7.02 mmol) of 
7-D-mandelamidocephalosporanic acid sodium salt and 1.31 g (15.64 mmol) of 
sodium bicarbonate in 55 ml of water was stirred at 70.degree. for 5.5 
hours while maintaining the pH at 7.0 by addition of 5% aqueous sodium 
bicarbonate. The mixture was chromatographed on XAD-7 resin and eluted 
with water. The product-containing fractions were lyophilized and the 
lyophilized material was recrystallized from methanol-ether. The product 
was taken up in water and lyophilized to give the title compound as the 
disodium salt. 
C.sub.20 H.sub.16 N.sub.4 O.sub.8 S.sub.2.sup.. 2 Na .sup.. 2 H.sub.2 O 
.sup.. 0.14 C.sub.4 H.sub.10 O. Calculated: 41.98%, C; 3.61%, H; 9.38%, N. 
Found: 41.70%, C; 3.80%, H; 8.72% N. 
7-D-Mandelamido-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephem 
-4-carboxylic acid disodium salt is dissolved in methanol containing a 
little water and stirred with Amberlite IR-120H ion exchange resin to give 
the title compound. 
EXAMPLE 2 
7-(D-.alpha.-Aminophenylacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylt 
hiomethyl)-3-cephem-4-carboxylic acid 
A mixture of 5.22 g (10.0 mmol) of 
7-(D-.alpha.-t-butoxycarbonylaminophenylacetamido)cephalosporanic acid and 
2.40 g (15.0 mmol) of 2-carboxymethyl-1,3,4-oxadiazole-5-thiol in 75 ml of 
pH 6.4 phosphate buffer solution is treated with sufficient solid sodium 
bicarbonate to give a pH of 6.4. The mixture is heated at 70.degree. for 
4.5 hours, cooled and acidified to pH 2.5 by addition of 3N hydrochloric 
acid and extracted with ethyl acetate. The extract is evaporated to 
dryness and the residue is chromatographed on silica gel to give 
7-(D-.alpha.-t-butoxycarbonylaminophenylacetamido)-3-(5-carboxymethyl-1,3, 
4-oxadiazol-2-ylthiomethyl)-3-cephem-4-carboxylic acid. 
7-(D-.alpha.-t-Butoxycarbonylaminophenylacetamido)-3-(5-carboxymethyl-1,3,4 
-oxadiazol-2-ylthiomethyl)-3-cephem-4-carboxylic acid is stirred at 
25.degree. with 25 ml of trifluoroacetic acid and 25 ml of 
1,3-dimethoxybenzene for 1.25 hours. The mixture is evaporated to dryness, 
ether is added to the residue and the precipitated salt is collected and 
dissolved in 350 ml of water containing a few drops of trifluoroacetic 
acid. The aqueous solution is treated with excess Amberlite IR-45 
ion-exchange resin to pH 2.7, then lyophilized to give the title compound. 
EXAMPLE 3 
Reaction of the N-t-butoxycarbonyl derivative of the following 
cephalosporanic acids: 
7-(.alpha.-amino-4 -hydroxyphenylacetamido)cephalosporanic acid 
7-(.alpha.-amino-4-formamidophenylacetamido)cephalosporanic acid 
7-(.alpha.-amino-3-formamidophenylacetamido)cephalosporanic acid 
7-(.alpha.-amino-4-ureidophenylacetamido)cephalosporanic acid 
7-(.alpha.-amino-3-ureidophenylacetamido)cephalosporanic acid 
7-(60 -amino-4-hydroxymethylphenylacetamido)cephalosporanic acid 
7-(.alpha.-amino-1,4-cyclohexadienylacetamido)cephalosporanic acid 
7-(.alpha.-amino-4-carboxymethylaminophenylacetamido)cephalosporanic acid 
with 2-carboxymethyl-1,3,4-oxadiazole-5-thiol as described in the procedure 
of Example 2 followed by removal of the protective group and conversion of 
the trifluoroacetic acid salt to the free acid as described therein gives 
the following compounds of this invention: 
7-(.alpha.-amino-4-hydroxyphenylacetamido)-3-(5-carboxymethyl-1,3,4-oxadiaz 
ol-2-ylthiomethyl)-3-cephem-4-carboxylic acid 
7-(.alpha.-amino-4-formamidophenylacetamido)-3-(5-carboxymethyl-1,3,4-oxadi 
azol-2-ylthiomethyl)-3-cephem-4-carboxylic acid 
7-(.alpha.-amino-3-formamidophenylacetamido)-3-(5-carboxymethyl-1,3,4-oxadi 
azol-2-ylthiomethyl)-3-cephem-4-carboxylic acid 
7-(.alpha.-amino-4-ureidophenylacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazo 
l-2-ylthiomethyl)-3-cephem-4-carboxylic acid 
7-(.alpha.-amino-3-ureidophenylacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazo 
l-2-ylthiomethyl)-3-cephem-4-carboxylic acid 
7-(.alpha.-amino-4-hydroxymethylphenylacetamido)-3-(5-carboxymethyl-1,3,4-o 
xadiazol-2-ylthiomethyl)-3-cephem-4-carboxylic acid 
7-(.alpha.-amino-1,4-cyclohexadienylacetamido)-3-(5-carboxymethyl-1,3,4-oxa 
diazol-2-ylthiomethyl)-3-cephem-4-carboxylic acid 
7-(.alpha.-amino-4-carboxymethylaminophenylacetamido)-3-(5-carboxymethyl-1, 
3,4-oxadiazol-2-ylthiomethyl)-3-cephem-4-carboxylic acid. 
EXAMPLE 4 
7-(4-Hydroxymandelamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl) 
-3-cephem-4-carboxylic acid is prepared by reaction of 
7-(4-hydroxymandelamido)cephalosporanic acid sodium salt, 
2-carboxymethyl-1,3,4-oxadiazole-5-thiol and sodium bicarbonate as 
described in the procedure of Example 1 followed by conversion of the 
product salt to the free acid as described therein. 
EXAMPLE 5 
When the sodium salt of a cephalosporanic acid listed below: 
7-(3-sydnoneacetamido)cephalosporanic acid 
7-(2-thienylacetamido)cephalosporanic acid 
7-(1-tetrazolylacetamido)cephalosporanic acid 
is reacted with 2-carboxymethyl-1,3,4-oxadiazole-5-thiol and sodium 
bicarbonate by the procedure described in Example 1 and the product is 
converted to the free acid as described therein, the following compounds 
of this invention are obtained, respectively: 
7-(3-sydnoneacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3 
-cephem-4-carboxylic acid 
7-(2-thienylacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3 
-cephem-4-carboxylic acid 
7-(1-tetrazolylacetamido)-3-(5-carboxyymethyl-1,3,4-oxadiazol-2-ylthiomethy 
l)-3-cephem-4-carboxylic acid. 
EXAMPLE 6 
7-(2-aminomethylphenylacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthi 
omethyl)-3-cephem-4-carboxylic acid 
When 7-(2-aminomethylphenylacetamido)cephalosporanic acid sodium salt is 
reacted with 2-carboxymethyl-1,3,4-oxadiazole-5-thiol and sodium 
bicarbonate by the procedure described in Example 1 and the product is 
converted to the free acid as described therein, the title compound is 
obtained. 
EXAMPLE 7 
7-Trifluoromethylthioacetamido-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiom 
ethyl)-3-cephem-4-carboxylic acid 
to an aqueous solution of 1.95 g (12.2 mmol) of 
2-carboxymthyl-1,34-oxadiazole-5-thiol and 2.05 g (24.4 mmol) of sodium 
bicarbonate in 35 ml of water is added 3.42 g (8.1 mmol) of 
7-trifluoromethylthioacetamidocephalosporanic acid sodium salt. The 
reaction mixture is stirred at 70.degree. for 4.5 hours, then cooled and 
chromatographed on XAD-2 resin with water and methanol as eluants. The 
product-containing fractions are combined and evaporated to dryness to 
give a residue which is stirred with 30 ml of water. Ethyl acetate is 
added and the resulting mixture is filtered. The layers are separated and 
the aqueous phase is lyophilized to give 
7-trifluoromethylthioacetamido-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthio 
methyl)-3-cephem-4-carboxylic acid disodium salt. 
7-Trifluoromethylthioacetamido-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiom 
ethyl)-3-cephem-4-carboxylic acid disodium salt is dissolved in a minimum 
amount of water to which ethyl acetate is added. While stirring, 3N 
hydrochloric acid is added until the solution is acidified to pH 2.5. The 
layers are separated, the aqueous phase is extracted with ethyl acetate 
and the combined extracts are washed with water, dried (MgSO.sub.4) and 
evaporated to dryness to give the title compound. 
EXAMPLE 8 
Reaction of the sodium salt of a cephalosporanic acid listed below: 
7-(2,2,2-trifluoroethylthioacetamido)cephalosporanic acid 
7-trifluoromethylsulfinylacetamidocephalosporanic acid with 
2-carboxymethyl-1,3,4-oxadiazole-5-thiol and sodium bicarbonate as 
described in the procedure of Example 7 gives, after conversion of the 
product salts to the free acids as described therein, the following 
compounds of this invention as final products: 
7-(2,2,2-trifluoethylthioacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2-yl 
thiomethyl)-3-cephem-4-carboxylic acid 
7-trifluoromethylsulfinylacetamido-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylt 
hiomethyl-3-cephem-4-carboxylic acid 
EXAMPLE 9 
7-Amino-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephem-4-carbo 
xylic acid 
A solution of 9.61 g (0.06 mol) of 2-carboxymethyl-1,3,4-oxadiazole-5-thiol 
in 120 ml of acetone is added to a warm (45.degree.) solution of 10.9 g 
(0.04 mol) of 7-aminocephalosporanic acid in a mixture of 220 ml of water, 
50 ml of acetone and 13.44 g (0.16 mol) of sodium bicarbonate. The 
temperature is raised to 65.degree. and the pH maintained at 7.4-7.6 by 
addition of aqueous sodium carbonate solution. After 3 hours, the acetone 
is removed in vacuo and the reaction mixture is cooled to 10.degree. and 
adjusted to pH 3.5 by addition of dilute hydrochloric acid. The product is 
collected, washed with water and then acetone to give the title compound. 
EXAMPLE 10 
When an equivalent amount of an acid chloride prepared from the following 
acid esters: 
succinic acid monomethyl ester 
glutaric acid monomethyl ester 
adipic acid monoethyl ester 
pimelic acid monomethyl ester 
by treatment with thionyl chloride or phosphorus pentachloride is used in 
the procedure of Example 1 in place of ethyl malonyl chloride in the 
reaction with dithiocarbazic acid potassium salt and the resulting ester 
substituted oxadiazole compounds are hydrolyzed as described therein, the 
following acid substituted oxadiazole thiols are prepared: 
2-(2-carboxyethyl)-1,3,4-oxadiazole-5-thiol 
2-(3-carboxypropyl)-1,3,4-oxadiazole-5-thiol 
2-(4-carboxybutyl)-1,3,4-oxadiazole-5-thiol 
2-(5-carboxypentyl)-1,3,4-oxadiazole-5-thiol. 
Reaction of a 2-carboxyalkyl-1,3,4-oxadiazole-5-thiol listed above with 
7-D-mandelamidocephalosporanic acid sodium salt and sodium bicarbonate 
according to the procedure described in Example 1 followed by conversion 
of the salts formed to the free acids gives the following compounds of 
this invention: 
7-D-mandelamido:3-[5-(2-carboxyethyl)-1,3,4-oxadiazol-2-ylthiomethyl]-3-cep 
hem-4-carboxylic acid 
7-D-mandelamido-3-[5-(3-carboxypropyl)-1,3,4-oxadiazol-2-ylthiomethyl]-3-ce 
phem-4-carboxylic acid 
7-D-mandelamido-3-[5-(4-carboxybutyl)-1,3,4-oxadiazol-2-ylthiomethyl]-3-cep 
hem-4-carboxylic acid 
7-D-mandelamido-3-[5-(5-carboxypentyl)-1,3,4-oxadiazol-2-ylthiomethyl]-3-ce 
phem-4-carboxylic acid. 
Likewise, reaction of the substituted oxadiazole thiols listed above with 
any of the 7-acyl cephalosporanic acids mentioned herein or their 
corresponding salts according to procedures described herein gives the 
corresponding compounds of this invention. 
EXAMPLE 11 
7-(2,2,2-Trifluoroethylsulfinylacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazo 
l-2-ylthiomethyl)-3-cephem-4-carboxylic acid 
To a stirred solution of 5.7 g (0.03 mol) of 
2,2,2-trifluoroethylsulfinylacetic acid and 3.45 g (0.03 mol) of 
N-hydroxysuccinimide in 50 ml of tetrahydrofuran at 0.degree. is added 6.2 
g (0.031 mol) of dicylohexylcarbodiimide. The reaction mixture is stirred 
at 0.degree. for 1 hour then at 25.degree. for 12 hours. The precipitate 
is filtered and washed with tetrahydrofuran and the filtrate is evaporated 
to dryness to give the activated ester of 
2,2,2-trifluoroethylslfinylacetic acid. 
A suspension of 3.4 g (0.01 mol) of 
7-amino-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephem-4-carb 
oxylic acid in 50 ml of dry dimethylformamide is treated with 2 of 
triethylamine and the mixture is stirred for 15 minutes at 25.degree.. A 
slight excess of 0.01 mol of the activated ester of 
2,2,2-trifluoroethylsulfinylacetic acid is added to the mixture and it is 
stirred an additional hour. The reaction mixture is evaporated to dryness 
in vacuo and water and ethyl acetate are added to the residue. The layers 
are separated, the ethyl acetate layer is discarded, fresh ethyl acetate 
is added to the aqueous phase and it is acidified to pH 2.5 by addition of 
6N hydrochloric acid. The mixture is filtered, the layers are separated 
and the aqueous phase is extracted with ethyl acetate. The combined 
extracts are washed with water, dried (MgSO.sub.4) and evaporated to 
dryness to give the title compound. 
EXAMPLE 12 
7-Methylthioacetamido-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3- 
cephem-4-carboxylic acid 
To a stirred, cooled (-20.degree.) solution of 8.8 g (0.026 mol) of 
7-amino-2-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephem-4-carb 
oxylic acid in 220 ml of 3% sodium bicarbonate and 220 ml of acetone is 
added dropwise a solution of 3.66 g (0.029 mol) of methylthioacetyl 
chloride in 52 ml of acetone, during which time the pH of the reaction 
mixture is maintained at 8.0 by addition of 10% sodium hydroxide. After 
addition the reaction mixture is stirred an additional 20 minutes at 
-15.degree., then is warmed to 25.degree. and extracted with ether. The 
remaining aqueous phase is cooled, 250 ml of ethyl acetate is added and 
the slurry is acidified with 3N hydrochloric acid. The layers are 
separated and the aqueous phase is extracted twice more with ethyl 
acetate. The combined extracts are dried (MgSo.sub.4) and evaporated to 
dryness to yield the title compound. 
EXAMPLE 13 
7-(D-.alpha.-Formyloxyphenylacetamido)- 
3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephem-4-carboxylic 
acid 
A mixture of 3.4 g (0.01 mol) of 
7-amino-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephem-4-carb 
oxylic acid, 3.97 g (0.02 mol) of the former ester of D-mandeloyl chloride 
and 3.36 g (0.04 mol) of sodium bicarbonate in 100 ml of water and 140 ml 
of acetone is stirred in the cold for 1 hour, then at 25.degree. for 2 
hours. The acetone is evaporated in vacuo and the remaining aqueous 
mixture is extracted with ethyl acetate. The aqeuous solution is added 
with stirring to a cold mixture of 100 ml of water and 200 ml of ethyl 
acetate and the pH of the resulting mixture is adjusted by 2.0 by addition 
of 6N hydrochloric acid. The mixture is filtered, the layers are separated 
and the ethyl acetate layer is washed with water, dried (MgSO.sub.4) and 
evaporated to dryness to give the title compound. 
EXAMPLE 14 
Acylation of 
7-amino-3-(5-caboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephem-4-carbo 
xylic acid with an activated derivative of an acid listed below: 
cyanoacetic acid 
cyanomethylthioacetic acid 
3-pyridylthioacetic acid 
4-pyridylthioacetic acid 
2-pyridone-N-acetic acid 
4-pyridone-N-acetic acid 
as described in the procedure of Example 11 gives the following compounds 
of this invention: 
7-cyanoacetamido-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephe 
m-4-carboxylic acid 
7-cyanomethylthioacetamido-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethy 
l)-3-cephem-4-caboxylic acid 
7-(3-pyridylthioacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethy 
l)-3-cephem-4-carboxylic acid 
7-(4-pyridylthioacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethy 
l)-3-cephem-4-carboxylic acid 
7-(2-pyridoneacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)- 
3-cephem-4-carboxylic acid 
7-(4-pyridoneacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)- 
3-cephem-4-carboxylic acid. 
EXAMPLE 15 
Reaction of a cephalosporanic acid listed below or its corresponding salt: 
7-(.alpha.-hydroxy-2-thienylacetamido)cephalospranic acid 
7-(.alpha.-carboxy-2-tienylacetamido)cephalosporanic acid 
7-(.alpha.-sulfophenylacetamido)cephosporanic acid 
with 2-carboxymethyl-1,3,4-oxadiazol-5-thiol in the presence of sodium 
bicarbonate by procedures described hereinabove gives, after conversion of 
the products to the free acids, the following compounds of this invention: 
7-(.alpha.-hydroxy-2-thienlyacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2 
-ylthiomethyl)-3-cephem-4-carboxylic acid 
7-(.alpha.-carboxy-2-thienylacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2 
-ylthiomethyl)-3-cephem-4-carboxylic acid 
7-(.alpha.-sulfophenylacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthi 
omethyl)-3-cephem-4-carboxylic acid 
EXAMPLE 16 
7-(2,2,2-Trifluoroethylsulfonylacetamido)-3-(5-carboxymethyl-1,3,4-oxadiazo 
l-2-ylthiomethyl)-3-cephem-4-carboxylic acid 
To a suspension of 1.86 g (5 mmol) of 
7-amino-3-(5-carboxylmethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephem-4-car 
boxylic acid in 50 ml of methylene chloride is dropwise added over a 30 
minute period 6.0 g (0.03 mol) of O-t-butyl-N,N'-diisopropylpseudourea in 
10 ml of methylene chloride. The reaction mixture is stirred at ambient 
temperature for 78 hours then filtered. The filtrate is concentrated and 
200 ml of benzene is added to the residue. The benzene solution is 
filtered and the filterate is stirred with 1N hydrochlric acid in an ice 
bath for 30 minutes. The layers are hydrochloric acid and in an ice bath 
for 30 minutes. The layers are separated and the organic phase is again 
treated with hydrochloric acid. The acidic aqueous phases are combined, 
adjusted to pH 7.5 by addition of solid sodium bicarbonate and extracted 
with ethyl acetate. The extract is dried (MgSO.sub.4), filtered and 
evaporated to dryness to give 
7-amino-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephem-4-carb 
oxylic acid di-t-butyl ester. 
To a solution of 5.24 g (0.019 mol) of 
7-amino-3-(5-carboxymethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephem-4-carb 
oxylic acid di-t-butyl ester and 3.9 g (0.019 mol) of 
2,2,2-trifluoroethylsulfonylacetic acid in tetrahydrofuran is added 
dropwise a solution of 3.9 g (0.019 mol) of dicyclohexyoacarbodiimide in 
100 ml of tetrahydrofuran. The reaction mixture is stirred at 25.degree. 
for 12 hours, then filtered and concentrated to about 10 ml. The residue 
is filtered and evaporated to dryness to give 
7-(2,2,2-trifluoroethylsulfonylacetamido)-3-(5-carboxymethyl-1,3,4-oxadiaz 
ol-2-ylthiomethyl)-3-cephem-4-carboxylic acid di-t-butyl ester. 
The diester is dissolved in acetonitrile and trifluoroacetic acid is added. 
The solution is stirred for 3 hours and then added to rapidly stirring 
ether to precipitate the title compound. 
EXAMPLE 17 
7-D-Mandelamido-3-(5-carbamoylmethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-ceph 
em-4-carboxylic acid 
A solution of 1.88 g (0.01 mol) of 
2-carbethoxymethyl-1,3,4-oxadiazol-5-thiol in 25 ml of absolute ethanol is 
added dropwise at ambient temperature to 100 ml of a saturated solution of 
anhydrous ammonia in absolute ethanol. When the reaction is complete, as 
evidenced by thin layer chromatography, the solution is evaporated to 
dryness. The residue is dissolved in 100 ml of water and the aqueous 
solution is acidified to pH 2.5 with dilute hydrochloric acid and 
extracted with ethyl acetate. The extract is dried (MgSO.sub.4) and 
evaporated to dryness to give 2-carbamoylmethyl-1,3,4-oxadiazole-5-thiol. 
2-Carbomylmethyl-1,3,4-oxadiazole-5-thiol (12.4 g, 7.82 mmol), 3.00 (7.02 
mmol) of 7-D-mandelamidocephalosporanic acid sodium salt and 0.66 g (7.82 
mmol) of sodium bicarbonate are reacted as described in the procedure of 
Example 1. After cooling, the reaction mixture is acidified to pH 2.0 and 
extracted with ethyl acetate. The extracts are combined and dried and the 
solvent is evaporated to give the title compound. 
EXAMPLE 18 
7-D-Mandelamido-3-[5-(N-methylcarbamoylmethyl)-1,3,4-oxadiazol-2-ylthiometh 
yl]-3-cephem-4-carboxylic acid 
Reaction of 2-carbethoxymethyl-1,3,4-oxadiazole-5-thiol and methylamine 
according to the procedure of Example 17 gives 
2-(N-methylcarbamoylmethyl)-1,3,4-oxadiazole-5-thiol. 
2-(N-Methylcarbamoylmethyl)-1,3,4-oxadiazole-5-thiol, 
7-D-mandelamidocephalosporanic acid sodium salt and sodium bicarbonate are 
reacted as described in the procedure of Example 17. After cooling, the 
reaction mixture is acidified and extracted with ethyl acetate. The 
extract is dried and evaporated to dryness to give the title compound. 
EXAMPLE 19 
7-D-Mandelamido-3-[5-(N,N-dimethylcarbamoylmethyl)-1,3,4-oxadiazol-2-ylthio 
methyl]-3-cephem-4-carboxylic acid 
Substitution of dimethylamine in the procedure of Example 17 in place of 
ammonia in the reaction with 2-carbethoxymethyl-1,3,4-oxadiazole-5-thiol 
gives 2-(N,N-dimethylcarbamoylmethyl)-1,3,4-oxadiazole-5-thiol. 
2-(N,N-Dimethylcarbamoylmethyl)-1,3,4-oxadiazole-5-thiol, 
7-D-mandelamidocephalosporanic acid sodium salt and sodium bicarbonate are 
reacted as described in the procedure of Example 17. After cooling, the 
reaction mixture is acidified and extracted with ethyl acetate. The 
extract is dried and evaporated to dryness to give the title compound. 
EXAMPLE 20 
Reaction of the ethyl ester of an acid substituted 1,3,4-oxadiazole-5-thiol 
listed in Example 10 with ammonia as described in the procedure of Example 
17 gives, after acidification, the following carbamoylalkyl substituted 
1,3,4-oxadiazole thiols: 
2-(2-carbamoylethyl)-1,3,4-oxadiazole-5-thiol 
2-(3-carbamoylpropyl)-1,3,4-oxadiazole-5-thiol 
2-(4-carbamoylbutyl)-1,3,4-oxadiazole-5-thiol 
2-(5-cabamoylpentyl)-1,3,4-oxadiazole-5-thiol. 
Substitution of a carbamoylaklyl substituted oxadiazole thiol listed above 
in the procedure described in Example 17 in place of 
2-carbamoylmethyl-1,3,4-oxadiazole-5-thiol gives the cephalosporin 
compounds of this invention listed below as final products: 
7-D-mandelamido-3-[5-(2-carbamoylethyl)-1,3,4-oxadiazol-2-ylthiomethyl]-3-c 
ephem-4-carboxylic acid 
7-D-mandelamido-3-[5-(3-carbamoylpropyl)-1,3,4-oxadiazol-2-ylthiomethyl]-3- 
cephem-4-carboxylic acid 
7-D-mandelamido-3-[5-(4-carbomoylbutyl)-1,3,4-oxadiazol-2-ylthiomethyl]-3-c 
ephem-4-carboxylic acid 
7-D-mandelamido-3-[5-(5-carbamoylpentyl)-1,3,4-oxadiazol-2-ylthiomethyl]-3- 
cephem-4-carboxylic acid. 
In a similar manner, other 
7-acyl-3-(5-carbamoylaklyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-cephem-4-carb 
oxylic acid of this invention are prepared by substitution of a 
2-carbamoylaklyl-1,3,4-oxadiazole-5-thiol in the appropriate procedure 
described herein-above. 
EXAMPLE 21 
When ethylamine, propylamine or butylamine is reacted with 
2-carbethoxymethyl-1,3,4-oxadiazole-5-thiol according to the procedure of 
Example 17, the following N-alkylcarbamoylaklyl substituted oxadiazole 
thiols are ultimately prepared: 
2-(N-ethylcarbamoylmethyl)-1,3,4-oxadiazole-5-thiol 
2-(N-propylcarbamoylmethyl)-1,3,4-oxadiazole-5-thiol 
2-(N-butylcarbamoylmethyl)-1,3,4-oxadiazole-5-thiol. 
Reaction of a substituted oxadiazole thiol listed above with 
7-D-mandelamidocephalosporanic acid sodium salt and sodium bicarbonate 
according to the procedure described in Example 17 gives the following 
compounds of this invention as final products: 
7-D-mandelamido-3-[5-(N-ethylcarbamoylmethyl)-1,3,4-oxadiazol-2-ylthiomethy 
l]-3-cephem-4-carboxylic acid 
7-D-mandelamido-3-[5-(N-propylcarbamoylmethyl)-1,3,4-oxadiazol-2-ylthiometh 
yl]-3-cephem-4-carboxylic acid 
7-D-mandelamido-3-[5-(N-butylcarbamoylmethyl)-1,3,4-oxadiazol-2-ylthiomethy 
l]-3-cephem-4-carboxylic acid. 
Similarly, the alkylcarbamoylalkyl substituted oxadiazole thiols listed 
above are substituted in the appropriate procedures described hereinabove 
to produce other 7-acyl cephalosporin compounds of this invention. 
EXAMPLE 22 
When diethylamine, dipropylamine or dibutylamine is substituted for ammonia 
in the procedure of Example 17, the follwing oxadiazole thiols are 
ultimately prepared: 
2-(N,N-diethylcarbamoylmethyl)-1,3,4-oxadiazole-5-thiol 
2-(N,N-dipropylcarbamoylmethyl)-1,3,4-oxadiazole-5-thiol 
2-(N,N-dibutylcarbamoylmethyl)-1,3,4-oxadiazole-5-thiol. 
Reaction of a substituted oxadiazole thiol listed above with 
7-D-mandelamidocephalosporanic acid sodium salt and sodium bicarbonate 
according to the procedure described in Example 17 gives the following 
compounds of this invention as final products: 
7-D-mandelamido-3-[5-(N,N-diethylcarbamoylmethyl)-1,3,4-oxadiazol-2-ylthiom 
ethyl]-3-cephem-4-carboxylic acid 
7-D-mandelamido-3-[5-(N,N-dipropylcarbamoylmethyl)-1,3,4-oxadiazol-2-ylthio 
methyl]-3-cephem-4-carboxylic acid 
7-D-mandelamido-3-[5-(N,N-dibutylcarbamoylmethyl)-1,3,4-oxadiazol-2-ylthiom 
ethyl]-3-cephem-4-carboxylic acid. 
By similar procedures, the other 
7-acyl-3-[5-(N,N-dialkylcarbamoylmethyl)-1,3,4-oxadiazol-2-ylthiomethyl] 
cephalosporin compounds of this invention are prepared by substitution of 
the dialkylcarbamoylmethyl substituted oxadiazole thiols listed above in 
the appropriate procedures described hereinabove. 
EXAMPLE 23 
An injectable pharmaceutical composition is formed by adding sterile water 
or sterile saline solution (2 ml) to 500 mg of 
7-D-mandelamido-3-(5-carboxylmethyl-1,3,4-oxadiazol-2-ylthiomethyl)-3-ceph 
em-4-carboxylic acid disodium salt. A unit dose is administered 
intramuscularly to a subject infected with an organism suscepticle to the 
compound as noted herebefore every 4 to 6 hours. Intravenous or drip 
administration is also similarly used. 
Pharmaceutical compositions of the other antibacterial compounds disclosed 
above may be formulated and used in a similar manner.