CA1097613A - Cephalosporin ethers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The present invention relates to a novel process for preparing cephalosporin ethers which comprises reacting a 7-acylamido-, or 7-amino-3-hydroxy-3-cephem-4-carboxylic acid ester with a diazoalkane. Removal of the ester group provides a 3-alkoxy-3-cephem acid. The 3-alkoxy-3-cephem acids are valuable antibiotic compounds.

Description

~7~

The present invention relates to a novel process for preparing ceph-alosporin ethers which comprises reacting a 7-acylamido-, or 7-amino-3-hyd-roxy-3-cephem-4-carboxylic acid ester with a diazoalkane. Removal of the ester group provides a 3-alkoxy-3-cephem acid. The 3-alkoxy-3-cephem acids are valuable antibiotic compounds.
This invention relates to the cephalosporin class of antibiotics.
In particular, it relates to cephalosporin ethers represented by the follow-ing general formula H

S
R-N
O-R

C=O
\OR

wherein R is hydrogen or an acyl group derived from a carboxylic acid, Rl is methyl, ethyl, 3-methyl-2-butenyl or diphenylmethyl, and R2 is hydrogen or an ester forming group.
Previously, numerous antibiotics of the cephalosporin class have been described. These antibiotics, all having the same basic ring structure com-prising the 4-membered ~-lactam ring fused to a 6-membered dihydrothiazine ring, differ from one another structurally and biologically in many respects.
Structurally, the known cephalosporin antibiotics differ in the nature of the 7-acylamido substituent and also in the nature of the substituent in the 3-position of the dihydrothiazine ring. The cephalosporanic acids, for example, - cephalothin, are characterized by an acetoxymethyl group in the 3-position.
The desacetoxycephalosporanic acids, for example, cephalexin, have a 3-methyl substituent. Numerous cephalosporins having a substituted methyl group in the 3-position have also been described. The desacetyl cephalosporins have a 3-hydroxymethyl substituent and 3-alkylthiomethylcephalosporins have also been described. Recently, certain 3-methoxymethylcephalosporins have been disclosed.
Also, cert~in 7-acylamido-3-cephem-4~carboxylic acids wherein the 3-position of the dihydrothiazine ring bears only a hydrogen atom have been . .

.
.

-6~3 described.
The present invention provides a process for preparing cephalosporin antibiotic compounds of the above formula wherein an ether group is attached directly to the 3-position of the dihydrothiazine ring.
As described in our copending Canadian application number 186,650, filed November 26, 1973, 7-acylamido-, or 7-amino-3-methylenecepham-4-car-boxylic acid esters are reacted with ozone to form an intermediate ozonide involving the 3-exomethylene moiety. Decomposition of the ozonide provides, 7-acylamido-, or 7-amino-3-hydroxy-3-cephem-4-carboxylic acid esters.
lOAccording to the process of the invention, the 3-hydroxy-3-cephem ester is then reacted, for example, with diazomethane or diazoethane to yeild a 3-methoxy- or a 3-ethoxy-3-cephem-4-carboxylic acid ester or an alkoxy nucleus ester, a 7-amino-3-alkoxy-3-cephem-4-carboxylic acid ester.
; The latter compound is acylated by known procedures with the desired der-ivative of a carboxylic acid to provide, alternatively, a 7-acylamido-3-alkoxy-3-cephem-4-carboxylic acid ester. Removal of the carboxylic acid protecting ester group, R27 provides the antibiotic compound wherein R is acyl and R2 is hydrogen.
The cephalosporing ethers provided by this invention are useful antibiotic substances which can be employed to combat infections caused by gram-positive and gram-negative microorganisms.
The cephalosporin compounds o~ this invention are represented by the following Formula I.

~R-N
~ N ~ ~ O-R
O
C-O
OR ~

I

wherein R is hydrogen, or an acyl group of the formula o R'-C-~7 l3 wherein R' is a) Cl-C7 alkyl, C3-C7 alkenyl? cyanomethyl, halomethyl, 4-a~ino-4-carboxybutyl, protected 4-amino-4-carboxybutyl; or b) the group R" wherein R" is 1,4-cyclohexyl-dienyl, phenyl, or phenyl substituted`by halogen, hydroxy, nitro, amino, cyano, Cl-C4 lower allcyl, Cl-C4 lower alkoxy, hydroxymethyl, aminomethyl, protected aminomethyl, carboxy or carboxy-methyl; or c) an arylalkyl group oE the formula R"-(Y) -CH2- wherein R"
is as defined above, Y is O or S, m is O or l; or d) a substituted arylalkyl group of the formula H
R" '-C-Z , wherein R" ' is R" as defined above, 2-thienyl or 3-thienyl, Z is hydroxy or protected hydroxy; or e) a heteroarylmethyl group of the formula R""-CH2- wherein R"" is 2-thienyl, 3-thienyl, 2-furyl, 3-furyl, 2-thiazyl,

2--oxazyl, 5-tetrazyl or 1 tetrazyl;
and wherein Rl is methyl or ethyl; and R2 is hydrogen or a carboxylic acid protecting ester forming group. The present invention also embraces pharm-aceutically acceptable non-toxic salts of the aforesaid compounds of Formula I when R2 is hydrogen.
The te~rns employed in the folegoing deflnitlon of the compounds of the invention have the following meanings when employed herein. The term, "Cl-C7 alkyl," refers ~o aliphatic hydrocarbon chains such as methyl9 ethyl, ~; ~-propyl, n-butyl, iso-butyl, n-hexyl, or n-heptyl. "C3-C7 alkenyl" has ref-erence to the unsaturated hydrocarbon chains such as propenyl (allyl), butenyl, pentenyl, hexenyl, or heptenyl. "Halomethyl" refers to chloromethyl or bromomethyl.
When in the above de~inition R" represents a substituted phenyl group, R" can be a mono or disubstituted halophenyl group such as 4-chloro-' ~

: .. , , . : . .

a76~

phenyl, 2,6-dichlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 3-chloro-phenyl, 3-bromophenyl, 4-bromophenyl? 3,4-dibromophenyl, 4-fluorophenyl, or 2-fluorophenyl; a mono or dihydroxyphenyl group such as 4-hydroxyphenyl, 3-hydroxyphenyl, or 2,4-dihydroxyphenyl; a mononitrophenyl group such as 3- or 4-nitrophenyl; a monoaminophenyl group such as 4-aminophenyl, 3-aminophenyl or 2-aminophenyl; a cyanophenyl group, for example, 4-cyanophenyl; a mono or disubstituted lower alkylphenyl group such as ~-methylphenyl, 2,4-dimethyl-phenyl, 2-methylphenyl, 4-isopropylphenyl, 4-ethylphenyl, or 3-n-propylphenyl;
a mono or disubstituted lower alkyl phenyl ether for example, 2,6-dimethoxy-phenyl, 4-methoxyphenyl, 3-ethoxyphenyl, 4-isopropoxyphenyl, 4-t-butoxyphenyl,

3-ethoxy-4-methoxyphenyl; an aminomethylphenyl group such as 3- or 4- amino-methylphenyl; a carboxyphenyl group such as 3- or 4-carboxyphenyl; or R" rep-resents a carboxymethylphenyl group such as a 3- or 4-carboxymethylphenyl group. Also, R" represents disubstituted phenyl groups wherein the substit-uents can be different fcr example, 3-methyl-4-hydroxyphenyl, 3-chloro-4-hydroxyphenyl, 2-methoxy-4-bromophenyl, 4-ethyl-2-hydroxyphenyl, 3 hydroxy-

4-nitrophenyl, or 2-hydroxy-4-carboxyphenyl.
The term, "protected amino" as employed in the above definition has refere~ce to an amino group substituted with one of the commonly employed amino blocking groups sucb as the t-butyloxycarbonyl group (t-BOC), the benzyl-oxycarbonyl group, the p-me-thoxybenzyloxycarbonyl group, the p-nitrobenzyl-oxycarbonyl group, the 2,2,2-trichloroethyloxycarbonyl group, the l-carbo-methoxy-2-p-ropenyl group formed with methyl acetoacetate, or the trimethyl-silyl group. When in the Formula I, ~' is the 4 amino-4-carboxybutyl group, then ln addition to the above amino protecting groups the chloroacetyl,~prop-ionyl and 2,4-dichlorobenzoyl groups can be employed to advantage in protect-ing the amino group thereof.
The term "protected hydroxy" has reference to the readily cleavable groups formed with an hydroxyl group such as the formyloxy group, the chloro-acetoxy group, the benzhydryloxy group, the trityloxy group, the p-nitrobenzy-loxy group, or the trimethylsilyl group. 0 Illustrative of the acyl groups, R~ C as defined above are acetyl, s ~ - 4 -.
.

~a7~3 propionyl, butyryl, hexanoyl, heptanoyl, 2-pentenoyl, acryloyl, 5-aminoadi-poyl, chloroacetyl, or bromoacetyl~ O
Representative of the acyl groups R"-C-, are benzoyl, 2,6-dimethoxy-benzoyl, 4-chlorobenzoyl, 4-methylbenzoyl, 3,4-dichlorobenzoyl, 4-cyano-benzoyl, 3-bromobenzoyl, 3-aminobenzoyl or 4-nitrobenzoyl.
Illustrative of the acyl groups R~-C-, when ~' is a group of the Eormula ~'-(Y)m-CH2- and m i5 O, are cyclohexa-1,4-diene-1-acetyl, phenyl-acetyl, 4-chlorophenylacetyl, 3-hydroxyphenylacetyl, 4-carboxyphenylacetyl, 3-cyanophenylacetyl, 4-aminophenylacetyl, 4-hydroxy-3-methylphenylacetyl, 4-bromophenylacetyl, 4-ethoxyphenylacetyl, 4-nitrophenylacetyl, or 3,4-dimeth-oxyphenylacetyl; and when m is 1 and Y is 0, representative acyl groups are phenoxyacetyl, 3-hydroxyphenoxyacetyl, 4-chlorophenoxyacetyl, 3,4-dichloro-phenoxyacetyl, 2-chlorophenoxyacetyl, 4-methoxyphenoxyacetyl, 3-aminophenoxy-acetyl, 4-carboxymethylphenoxyacetyl, 4-aminoethylphenoxyacetyl, 2-ethoxy-phenoxyacetyl, 3,4-dimethylphenoxyacetyl, 4-isopropylphenoxyacetyl, 3-cyano-phenoxyacetyl, or 3-nitrophenoxyacetyl; and when m is 1 and Y is S, rep-; resentative thiophenoxyacetyl groups are thiophenoxyacetyl, 2,6-dichlorothio-: phenoxyacetyl, 4-chlorothiophenoxyacetyl, 4-cyanothiophenoxyacetyl, 3-bromo-thiophenoxyacetyl or 3-aminothiophenoxyacetyl.
Illustrative of the acyl groups when R' is a substituted arylalkyl group of the formula H
R." '--C--Z
: are the hydroxy substituted arylalkyl groups such as the mandeloyl group of the formula O

CE~--C--\ - / OH
and the substituted mandeloyl groups, for example, 4-methoxymandeloyl, 4-hydroxymandeloyl, 3,4-dichloromandeloyl, 3-cyanomandeloyl, 3-bromomandeloyl, 3-hydroxymandeloyl, 4-aminomandeloyl, 3-nitromandeloyl, 4-fluoromandeloyl, 4-carboxymandeloyl, 4-carboxymethylmandeloyl or 4-aminomethylmandeloyl; or ~7~

such groups as Il 11 0 \ S CH-C-z or o rc H - C

wherein Z is a hydroxy or protected hydroxy group.
Representative of the acyl group R'-C-, when R' is a heteroarylmethyl group of the formula R " '-CH2- are, 2-thienylacetyl, 3-thienylacetyl, 2-fury-lacetyl, a 2-oxazylacetyl group of the formula P~ O
CH~ -C-O
a 2-thiazylacetyl group of the formula S ~ CH~ -C-or a l-tetrazylacetyl group of the formula CH~

The cephalosporin~ ethers defined above, can be prepared by a div-ersity oE synthe-tic routes. The starting~material in each instance is a 3-hydroxy-3-cephem-4-carboxylic acid ester. These starting materials are pre-pared, as described in our copending Canadian application number 186,650, by reacting a 7-acylamidocephalosporanic acid with a sulfur con~aining nucleo~
phile according to known procedures to effect the nucleophilic displacement `; of the acetoxy group of the cephalosporanic acid and provide a 7-acylamido-3-thiosubstituted methyl-3-cephem-4-carboxylic acid. The 3-thiosubstituted cephem product is then reduced with hydrogen in the presence of Raney nickel or with zinc/formic acid in the presence of dimethylformamide to produce an : - . .
~. , . ~, . .
. .
-- , ~7~3 3-exomethylenecepham acid The 3-exomethylenecepham nucleus can be prepared by reacting a 7-acylamido-3-exomethylenecepham-4-carboxylic acid ester with phosphorus pent~-chloride (PC15) in the presence of pyridine to obtain the intermediate imino chloride. The imino chloride is reacted with methanol in the cold to afford the imino ether. The imino ether readily undergoes hydrolysis to provide the 7-amino-3-exomethylenecepham-4-carboxylic acid ester. The ester group is then removed to yield the 3-exomethylenecepham nucleus.
The 7-acylamido-3-exomethylenecepham-4-carboxylic acid ester or an ester o~ the 3-exomethylenecepham nucleus is then reacted with ozone to form an intermediate ozonide which on decomposition yields the corresponding 3-hydroxy-3-cephem-4-carboxylic acid ester as illustrated by the following general reaction scheme.

~ ~ 'd ~ ~1~ 0 ~
COOR~ (1) COOR~

r N~ ~ 03 7~ ~ ~

O \I CH~ O ~ OH
COOR~ (2) COOR 7 According to the process of the pre~sent invention, the 7-acylamido-3-hydroxy-3-cephem ester (1) or the 3-hydroxy nucleus ester (2), or the Keto tautomer thereof, is reacted with diazomethane, diazoethane, diphenyldiazo-methane, or l-diazo-3-methyl-2-butene to provide the corresponding e~her com-pound as i]lustrated with diazomethane in the following reaction scheme.

~!

O H

(1) CH~=N. R'-C--N- ~ S
N ~ O-CH3 ~ N~

COOR
(3) H~N_____~" S
(2) CH~=N >
- N ~ OCH3 + N~

OOR~
(4) Alternatively, the 3-hydroxy nucleus ester (2) can be acylated to provide the 7-acylamido-3-hydroxy-3-cephem-4-carboxylic acid ester (1) which on re-action with the desired diazo compound yields the compound (3).
According to another synthetic pathway of the invention, the 3-alkoxy nucleus ester (4) can be acylated to provide a cephalosporin ether (3).
The antibiotic compounds of this in~ention, the 3-methoxy, ethoxy, diphenylmethyloxy and 3-methyl-2-butenyl-1-oxy-3-cephem-4-carboxylic acids (Formula I, R ~ R~ C ~ R2 = H) are prepared by reacting a 3-hydroxy-3-cephem-ester intermediate with the respective diazo compound. The ester forming group, R2, is then removed to provide the antibiotic compound represented by o the Formula I wherein R is an acyl group R~ C and R2 is hydrogen.
The diazo compounds employed in the present reaction are diazomethane, diazoethane, diphenyldiazomethane and l-diazo-3-methyl-2-butene. The diazo compounds are prepared by known procedure. and are readily available.
The etheriEication reaction is carried out by adding an ethereal sol-ution of the diazo compound to a solution of the 3-hydroxy cephalosporin ester in an inert solvent. An excess of the diazo compound is desirable. The ëtherification proceeds at a satisfactory rate at a temperature between about 20 and 25C. Inert solvents which can be employed are those which are un-reac~ive toward the diazo compound and preferably the chlorinated hydrocarbon solvents~ for example methylene chloride and chloroform.
The rate of the etherification reaction can be enhanced by the add-ition of a catalytic amount of boron trifluoride etherate to the reaction . .
.

76~3 mixture. Ordinarily the etherification reaction with diazomethane proceeds to completion in ~bout 2 hours.
The cephalosporin ethers are readily recovered from the etherifica-tion reaction mixture and purified by evaporation of the mixture to dryness and crystallization of the resiclue~
The 3-hydroxy-3-cephem esters can also be reacted with etherifying reagents other than diazo compounds, to provide varying ether substituents.
For example, the 3-hydroxy-3-cephem esters can be reacted in the presence of a base with methyl iodlde, a lower alkyl ester of sulfuric acid such as dim-ethyl sulfate or with trimethyl oxonium fluoroborate to provide the methylether or a higher homolog thereof. Activated halo compounds can also react in the presence of a base with the 3-hydroxy-3-cephem esters to provide other ether derivatives. For example, activated halo compounds such as the d-halo-ethers, chloromethyl methyl ether and bromomethyl ethyl ether; d-haloacid esters such as ethyl bromoacetate, methyl chloroacetate, ethyl ~-bromopro-pionate; and allylic halides such as allyl bromide and allyl chloride can react to provide 3-cephem-3-ethers. The preparation of 3-cephem-3-ethers with the above mentioned reagents is accompanied by alkylation in the 4-position of the dihydrothiazine ring. For example, methyl iodide reacts with p-nitrobenzyl 7-phenylacetamido-3-hydroxy-3-cephem-4-carboxylate in the presence of a base to yield a reaction product mixture comprising the desired 3-methoxy ether, the 4-methyl-3-hydroxy-2-cephem-4-carboxylate and the 4-methyl-3-methoxy-2-cephem-4-carboxylate. Such mixtures can be separated by chromatography to provide the desired 3-ether.
The preferred etherifying reagents, the above named diazo compounds such as diazomethane, react with the 3-hydroxy-3-cephem esters to provide the 3-cephem ethers without concurrent alkylation in the 4-position.
In a specific embodiment of this invention p-nitrobenzyl 7-[2~(2--thienyl)acetamido]-3-hydroxy-3-cephem-4-carboxylate is dissolved in methy-lene chloride and a solution of excess diazomethane in methylene chloride is added. The reaction mixture is stored at room temperature for 2 hours, the solvent evaporated, and the residue dissolved in ethyl acetate. The ethyl _ 37~

acetate solution is chilled to precipitate p-nitrobenzyl 7-[2-(2-thienyl) acetamido]-3-methoxy-3-cephem-4-carboxylate as a crystalline solid.
In a similar manner the 3-ethoxy compound is prepared with diazo-ethane.
~ s described in the methods and procedures of this invention the carboxylic acid group of the cephalosporin compound is protected with a cleavable ester forming group such as one of those previously listed. Like-wise, in t~e case of the compounds of the Formula I wherein the acylamido group bears an hydroxyl group or an amino group substituent, as for example the mandeloyl and aminoadipoyl groups, or a carboxylic acid group, such reactive functions are protected with a cleavable blocking group. The car-boxylic acid, amino and hydroxyl group protecting groups which are described herein are only illustrative of the many known protecting groups which will be recognized as applicable in this invention. The only requirement is that such groups be stable blocking groups under the described conditions of ozo-nolysis, acylation and etherification and that they be readily removed by acid or base hydrolysis or catalytic hydrogenolysis under conditions which are not destructive of the cephalosporin molecule.
Preferred carboxylic acid protecting groups of the present invention are the p-ni~robenzyl, p-methoxybenzyl and benzhydryl groups. The p-nitro-benzyl ester group is removed by catalytic hydrogenolysis under acidic con-ditions. The p-methoxybenzyl and benzhydryl groups are cleaved with tri-fluoroacetic acid at O-10C. in anisole, as described by J. Org. Chem., 36, 1259 (1971). However, other carboxylic acid protecting ester forming groups such as the benzyl, 2,2,2-trichloroethyl and t-butyl groups can be employed.
Preferred hydroxyl group protecting groups are the formyl group and the methoxy ethyl group, CH30-CH~CH3, formed by the reaction of the hydroxyl ~ group with me~hyl vinyl ether.
- Preferred amino protecting groups are ~he t-butyloxy-carbamido group, and the 1-carbomethoxy-2-propenyl group prepared by the condensation of the amino group with acetoacetic ester.

Following the preparation o e a cephalosporin ether (Formula I) the ~7~3 carboxylic acid protecting ester group and, if such are pre~ent in the side chain, the hydroxyl and amino protecting groups are removed to provide an antibiotic compound. Accordingly, the cephalosporin esters, protected amino compounds and protected hydroxyl group compounds are useful as intermediates in the preparation of the cephalosporin ether ant:ibiotics.
Illustrative of the cephalosporin antibiotics provided by the process of this invention are the following:
7-acetamido-3-methoxy-3-cephem-4-carboxylic acid, 7-propionamido-3-methoxy-3-cephem-4-carboxylic acid, 7-cyanoacetamido-3-methoxy-3-cephem-4-carboxylic acid, 7-chloroacetamido-3-methoxy-3-cephem-4-carboxylic acid, 7-phenylacetamido-3-methoxy-3-cephem-4-carboxylic acid, 7-(4-chlorophenylacetamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(4-methoxyphenylacetamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(3,4-dichlorophenoxyacetamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-phenoxyacetamido-3-ethoxy-3-cephem-4-carboxylic acid, 7-thiophenoxyacetamido-3-methoxy-3-cephem-4-carboxylic acid, 7-(4-chlorothiophenoxyacetamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-phenoxyacetamido-3-methoxy-3 cephem-4-carboxylic acid, 7-acetamido-3-ethoxy-3-cephem-4-carboxylic acid, 7-(4-hydroxyphenoxyacetamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-benzamido-3-methoxy-3-cephem-4-carboxylic acid, 7-(2,6-dimethoxybenzamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(3,4-dichlorobenzamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(3-bromobenzamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(2-chlorophenoxyacetamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(4-cyanophenylacetamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(4-nitrophenylacetamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-[2-(2-thienyl)acetamîdo]-3-methoxy-3-cephem-4-carboxylic acid, 7-[2-(2-thienyl)acetamido]-3-e-thoxy-3-cephem-4-carboxylic acid, 7-[2-(3-thienyl)acetamido]-3-methoxy-3-cephem-4-carboxylic acid, 7-[2-(2-~uryl)acetamidoJ-3-methoxy-3-cephem-4-carboxylic acid, . ., 9~3l3 7-~2~ tetrazyl)acetamido]-3-methoxy-3-cephem-4-carboxylic acid, 7~[2-(2-oxazyl)acetamido]~3~methoxy-3-cephem-4-carboxylic acid, 7-[2-(2-thiazyl)acetamido]-3-methoxy-3-cephem-4-carboxylic acid, 7-[2-(5-tetrazyl)acetamido]-3-methoxy-3-cephem-4-carboxylic acid, 7-(D-mandelamido)-3-methoxy-3-cephem-~-carboxylic acid, 7-(2-chlorothiophenoxyacetamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(D-4-hydroxymandelamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(D-3-hydroxymandelamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(D-3-methoxymandelamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(D-mandelamido)-3-ethoxy-3-cephem-4-carboxylic acid, 7~phenylacetamido-3-benzhydryloxy-3-cephem-4-carboxylic acid, 7-[2-(2-thienyl)acetamido]-3-(3-methyl-2-butenyl-1-oxy)-3-cephem-4-carboxylic acid, 7-phenoxyacetamido-3-benzhydryloxy-3-cephem-4-carboxylic acid, 7-acetamido-3-(3-methyl-2-butenyl-1-oxy)-3-cephem-4-carboxylic acid, 7-[2-(2-oxazyl)acetamido]-3-ethoxy-3-cephem-4-carboxylic acid, 7-(5-amino-5-carboxyvaleramido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(4-aminomethylphenylacetamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(4-carboxymethylphenylacetamido)-3-methoxy-3-cephem-4-carboxylic acid, and 7-(3-chloro-4-hydroxyphenoxyacetamido)-3-methoxy-3-cephem-4-carboxylate.
The cephalosporin ether nuclei (Formula I, R = M) are especially : valuable compounds since they can be acylated with the desired acyl group to prGvide an antibiotic compound (Formula I, R = acyl).
The acylation of these nuclei can be carried out by the known methods used for the acylation of 7-aminocephalosporanic acid or 7-aminodesacetoxy-cephalosporanic acid. The cephalospor-in ether nucleus acids or esters can be acylated under anhydrous acylation methods as well as in the presence of water. ~ccordingly, the cephalosporin ether~nucleus free acid or an ester thereof can be~acylated with a carboxylic acid halide in an aqueous solvent system, for example aqueous acetone, in the presence of a hydrogen halide ~ - 12 -7~3 acceptor such as triethyl amine, pyridine or sodium bicarbonate. The acyla-tion can also be effected by reacting an ester of the ether nucleus with a carboxylic acid ill the presence of a condensing agent such as N-ethoxycarbon-yl-2-ethoxyYl,2-dihydroquinoline (EEDQ) or dicyclohexylcarbodiimide. Also the ether nucleus ester can be acylated with the anhydride of a carboxylic acid or with a mixed anhydride. sy yet another known acylation method, the ether nucleus can be acylated with an active ester of a carboxylic acid, for example the pentachlorophenyl ester of a carboxylic acid.
For example, p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate is reacted with thiophene-2-acetyl chloride in aqueous acetone containing sodium bicarbonate to provide p-nitrobenzyl 7-~2-(2-thienyl)acetamido]-3-methoxy-3-ceyhem-4-carboxylate.
p-Nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate is reacted with phenoxyacetic acid in a tetrahydrofuranacetone solvent mixture in the presence of EEDQ to provide p-nitrobenzyl 7-[N-(t-butyloxycarbonyl)-D-~-phenylglycylamido]-3-methoxy-3-cephem-4-carboxylate.
p-Nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate is reacted with mandelic 0-carboxy-anhydride in ethyl acetate to provide p-nitrobenzyl 7-(D-~-mandelamido)-3-methoxy-3-cephem-4-carboxylate.
Illustrative of the acylating groups which can be employed in the above methods are thiophene-2-acetyl chloride, phenoxyacetyl chloride, pheny-lacetyl chloride, pentachlorophenyl thiophene-3-carboxylate, oxazole-2-acetyl bromide, thiazole-2-acetyl chloride, tetrazole-l-acetic acid, mandelic acid 0-carboxy anhydride, 4-hydroxymandelic acid O-carboxy anhydride, 4-chloro-phenoxyacetyl bromide, benzoyl chloride, 4-cyanobenzoyl chloride, 4-cyano-phenylacetyl chloride, and 3,4-dichlorothiophenoxyacetyl chloride.
Illustrative of the cephalosporin ether nucleus acids and esters thereof which are provided by the process of this invention are 7-amino-3-methoxy-3-cephem-4-carboxylic acid, 7-amino-3-ethoxy-3-cephem-4-carboxylic acid, p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate, p-methoxybenzyl 7-amino-3-methoxy-3-cephem 4-carboxylate, 2,2,2-trichloroethyl 7-amino-3-methoxy-3-cephem-4-carboxylate, 2,2,2-trichloroethyl 7-amino-3-ethoxy-3-cephem-4-carboxylate, diphenylmethyl 7-amino-3-methoxy-3-cephem-4-carboxylate, p-nitrobenzyl 7-amino-3-benzhydryloxy-3-cephem~4-carboxylate, 7-amino-3-benzhydryloxy-3-cephem-4-carboxylic acid, and p-nitrobenzyl 7-amino-3-(3-methyl-2-butenyl-1-oxy)-3-cephem-4-carboxylate.
The cephalosporin ether nucleus esters can also be prepared by the cleavage of the protected-aminoadlpoyl side chain from a 3-ether derivative of cephalosporin C. For example, 7-(5-propionamido-5-carboxyvaleramido)-3-methoxy-3-cephem-4-carboxylic acid dibenzhydryl ester is reacted with phos-phorus pentachloride in the presence of pyridine to provide the imino halide which on reaction with added methanol affords the methyl enol ether. The enol ether is readily hydrolyzed to yield benzhydryl 7-amino-3-methoxy-3-cephem-4-carboxylate. The side chain cleavage reaction is carried out by following the known PC15 cleavage conditions and procedures which are used in the cleavage of the aminoadipoyl side chain of cephalosporin C to provide a 7-aminocephalosporanic acid ester.
Accordingly, the 7-(5-protected amino-5-carboxyvaleramido)-3-hydroxy-3~cephem-4-carboxylic acid diesters wherein the protected amino group is the chloroacetamido, propionamido or 2,4-dichlorobenzamido group, are converted to the 3-ether derivatives (Formula I, R = 5-protected amino-5-carboxyval-eryl) by the etherification method of this invention as described previously.Accordingly 7-(5-propionamido-5-carboxyvaleramido)-3-methoxy-3-cephem-4-carboxylic acid, 7-(5-chloroacetamido-5-carboxyvaleramido)~3-methoxy-3-cephem-4-carboxylic acid and~ 7-[5-(2,4-dichlorobenzamido)-5-carboxyvaler-amido]-3-methoxy-3-cephem-4-carboxylic acid and the readily removable diest-ers thereof and notably the benzhydryl esters are a partlcularly useful group o~ compounds. Likewise, the correspondingly substituted 3-hydroxy-3-cephem esters are useEul starting materials for the preparation of these compounds.
Following the procedures described above the 7-methoxy derivative of cephalosporin C, which is obtained as a ermentation product of a Stree~omy-cete as described in J. Am~ Chem. Soc. 93~ 2308 (1971), can be converted to the 7-methoxy-3-hydroxy-3-cephem ester. Following the etherification reac-~ - 14 -~ . -7~3 tion disclosed herein the 3,7-dimethoxy-3-cephem ester can be prepared and on cleavage of the protected aminoadipoyl side chain with PC15 in the pres-ence of pyridine, an ester of 7-amino-3,7-dimethoxy-3-cephem-4-carboxylic acid, for example the benzhydryl or p-nitrobenzyl ester, is obtained. The 7-amino-3,7-dimethoxy nucleus ester can be acylated by known procedures to provide 7-acylamido-3,7-dimethoxy-3-cephem-4-carboxylates. Removal of the ester group provides an antibiotic 7-acylamido-3,7-dimethoxy-3-cephem-4-carboxylic acid. For example, 7-mandelamido-3,7-dimethoxy-3-cephem-4-carboxy-lic acid, 7-[2-(2-thienyl)-acetamido]-3,7-dimethoxy-3-cephem-4-carboxylic acid and the 7-~3- or 4-hydroxymandelamido)-3, 7-dimethoxy-3-cephem-4-carbox-ylic acid can be prepared.
The 3-etherified 7-arylamido-3-cephem-4-carboxylic acids (Formula I, R = R~ C Rl = methyl, ethyl, diphenylmethyl, or 3-methyl-2-butenyl, R2 =
hydrogen) are useful antibiotic compounds which inhibit the growth of gram-positive and gram-negative microorganisms.
In Table I which ~ollows, the minimum inhibitory concentration (MIC) of the compounds prepared by the process oE the invention is illustrated by the data presented for the listed compounds. The data were obtained by the standard agar disc method.

~ 7~

TABLE I

ANTIBIOTIC SPECTRUM OF CEPHALOSPORIN ETHERS
Disc-plate ~ethod . .
Antibiotic Concentration mg/ml Microorganlsm Zone of Inhibition (diameter in mm) A B
'1.0 0.1 0.01 1.0 0.1 0.01 . ~
Staphylococcus aureus 31 24 10 34 25 16 Bacillus subtilis 44 32 16 42 2i 15 Sarcina lutes 33~ 23 T 29 23 13 Mycobact rium avium T O - - - -S~accharomyces pastorianus - - - - - -Neurospora crassa - - - - - -.
Candida tropicalis - - - - - -mar1 m monilifo me - - - - - -Trichophyton mentagrophytes Proteus wlgaris ~ 20- l5 - 2-4 Salmonella gallinarum; 23 ~ T - 24 14 Escherchia coli ~ 21 13 - 28 16 - -Pseudomonas aeruginosa Klebsiella pneumoniae 23 13 - 23 15 .... _ . . :
Serratia marcescens . _~ , . . . _ . _ _ . _ Pseudomonas eolanacearcum 31 22 - 34 26 T
17 Compound A = 7-[2-(2-thienyl)acetamido]-3-methoxy-3-cephem-4-carboxylic acid.
Compound B = 7-(D-mandelamido)-3-me1:hoxy-3-cephem-4-carboxylic acid.

2/ A "T" indicates a trace æone of inhibition.
A dash indicatPs no observed- zone of inhibition at the test concentration.

~a 16-.

~7~L3 The following Table II lists the minimum inhibitory concentrations ~M¢C) for compounds prepared by the process of the invention against clinical isolates of penicillin resistant Staphylococcus both in the presence and absence of serum. The MIC values were determined by the Gradient Plate technique performed essentially as described by Byrson and Szybalski, Science, 6, 45, (1952).
Table II
Antibiotic Activity vs. Penicillin Resistant Stephylococcus 1 Staphylococcus Clinical Isolates Compound MIC (mcg/ml) 2 V-41 V-32X-400 V-84 Xl.l _ A ~20 ~20 ~20 ~20>20 ~20 4.8 >200.8 3.0 B 18.4 ~20 >20 ~20 ~20 ~20 9.4 11.1 0.6 0.5 1/ Compounds A and B are the compounds of footnoot l of Table I

2/ Methicillin resistant Staph_lococcus 3/ NS - no serum S - serum In Table III below, the MIC values for the test~compounds against representative gram-negative organisms is presented. The data were obtained by the Gradient Plate technique.

Table III

Antibiotic Activity vs. Gram-negative Organisms Organism MIC of Test Compound (mcg/ml) A B
. ~
_igella ~ 48.8 8.0 Escherichia coli 57.5 8.6 Klebsiella pneumoniae 11.2 4.5 Aerobacter ~ @~ 9.9 4.3 ~ . . .
Salmonella heidelberg 9.8 4.8 Pseudomonas aeruginosa >200 ~ 200 Serratia marcescens 7200 164 ll Compounds A and B are the compounds named in footnote 1 of Table I.

~ ~ ~L 4,o The cephalosporin ether antibiotics prepared by the process of this invention are relatively non-toxic substances which are useful in combating infections in warm blooded mammals when administered parenterally in a pharmaceutically effective non-toxic dosage form. The antibiotic ethers are effective in combatting infections when administered in a dose of about 25 to 50 mg/kg of body weight. In controlling infections in particular hosts repeated administration of smaller doses may suffice while in other instances larger non-toxic doses may be administered to achieve the desired control.
A preferred group of antibiotic compounds prepared by the process of this invention are the 3-methoxy cephalosporins represented by the Formula I
wherein R is an acyl group R~ C- Rl is methyl and R2 is hydrogen. A part-icularly preferred group of antibiotics are represented by the Formula I
wherein R' is the group H
~" '--C--z wherein Z is hydroxy, Rl is methyl and R2 is hydrogen. Illustrative of these preferred compounds are 7-~D-mandelamido)-3-methoxy-3-cephem-4-carbo~ylic acid, 7-(D-4-hydroxymandelamido~ -3-methoxy-3-cephem 4-carboxylic acid, 7-(D-3-hydroxymandelamido)-3-methoxy-3-cephem-4-carboxylic acid, 7-[2-(2-thienyl)-2-hydroxyacetamido]-3-methoxy-3-cephem-4-carboxylic acid and 7-[2-(3-thienyl)-2-hydroxyacetamido]-3-methoxy-3-cephem-4-carboxylic acid.
The antibiotic compounds prepared by the process of this invention can be administered in the free acid form or in the form of a pharmaceutically acceptable non-toxic salt such as the sodium or potassium salt. Such salts are prepared by reacting the antibiotic acid with a suitable base such as sodium carbonate, ~odium bicarbonate, sodium hydroxide, potassium carbonate and li~e bases.
The following examples are provided to further illustrate the inven-tion.

r :
~' '`I

Exam~le 1 p-Nitrobenzyl 7-amino-3-hydroxy-3~cephem-4-carboxylate hydrochloride.
~ solution of 3.85 g. o~ p-nitrobenzyl 7-amino-3-methylenecepham 4-carboxylate hydrochloride in 600 ml. of methanol was cooled in an acetone-dry ice bath. Ozone was bubbled through the reaction mixture for approxim-ately 20 minutes at ~hich time the reaction mixture developed a faint blue coloration. Nitrogen was then passed through the reaction mixture to expel excess ozone. Next, the intermediate ozonide was decomposed by passing sulfur dioxide gas through the reaction mixture until the mixture gave a negative potassium iodide-starch test.
The reaction mixture was evaporated in vacuo and the residue was dissolved in 200 ml. of 0.1N hydrogen chloride in methylene chloride. The solution was evaporated to dryness and the residual reaction product was dissolved in acetone. On cooling, 3.15g. of p-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxylate hydrochloride precipitated as a crystalline solid.
I.R. ("Nujol"* Mull):
; Carbonyl absorption at

5~55 k3-lactam carbonyl) and 5.02 (ester carbonyl hydrogen bonded to 3 hydroxy) microns.
Electrometric titration (66% DMF) pKa 4.0 and 6.3.
Example 2 p-Nitrobenzyl 7-amino~3-methoxy-3-cephem-4-carboxylate hydrochloride.
To a stirred suspension of 445 mg. of p-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxylate hydrochloride (prepared as described by ; Example 1) in 30 ml. of methylene chloride was added 131 mg. of mono-tri--; methylsilyl acetamide~and t~he~mixture was stirred~at room temperature for 30 min. An ethereal solution of excess diazomethane was added and after 20 min.
the mixture was evaporated to remove solvent and excess diazomethane. The residue was treated with 1 ml. of methanol and then dissolved in an ethyl acetate-water mixture. The ethyl acetate layer was separated, washed with * Trademark for a highly refined mineral oil. It is a colorless and odorless oily liquid; comprising a mixture of hydrocarbons.

,, -- 19 --water and dried. Hydrogen chloride was passed through the dried ethyl acetate layer to precipitate the reaction product, p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate hydrochloride, N.M.R. (D~S0 d6): signals at 6.97 (broad s, 3H, NH3), 6.31 (s, 2H, C2-H2), 6.23 (s, 3H, C3 methoxyl), 5.39 (d, lH, C6H), 5.05 (d, lH, C7H) and 2~5-1,92 (q, 4H, aromatic H) tau.
Example 3 p-Nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate.
To a stirred suspension o~ 445 mg. of p-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxylate hydrochloride (prepared as described by Example 1) in 35 ml. of dry tetrahydrofuran was added one equivalent of triethylamine followed by 10 ml. of an ethereal solution of diazomethane in excess. After 30 min. the solvent and excess diazomethane were evaporated and the residue was dissolved in a mixture of water and ethyl acetate. The organic layer was separated and was washed with water and dried. The dried ethyl acetate solution was èvaporated to dryness to yield 310 mg. of p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate. The product was obtained crystalline by trituration with diethyl ether.
Elemental analysis for C15H15N3~6S:
Theory: C, 49.31; H, 4.14; N, 11.50 Found: C, 49.51; H, 4.40; N, 11.25 I.R. ("Nujol" Mull): abeorptlon peaks at 2.99 (amide), 5.75 (broad, ~-lactam and ester carbonyl), and 5.98 (amide carbonyl) microns.
U.V. (ethano~ absorption maximum 268 mu.
~=14,600.
.M.R. (DMS0 d6): signals at 7.10 (broad s, 2H, ¢7NH2-), 6.22 (s, 2H, C2H2), 6,20 (s, 3H, C3 methoxyl), 5.27 (d, lH, C6H), 4.92 (d, lH, C7H), 4.60`(s,~2H, ester C~2), and 2.35-1.6 (q, 4H, aromatic H) tau.
Exam ~e 4 7-Amino-3-methoxy-3-cephem-4-carboxylic acid.
. solution of 730 mg. of p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-. . . .

~7~i~3 carboxylate (prepared as descrihed by ~xample 3) in 20 ml. of water and 20 ml. of acetonitrile was ~cidified momentarily to pH 1 with concentrated hydrochloric acid. Immediately ~herea~ter the solution was back titrated to pH 2.5 with lN sodium hydroxide. The solution was then evaporated to dry-ness and the residue was dissolved in a mixture of 40 ml. THF, 80 ml. of methanol and 6 ml. of water. The solutlon was then hydrogenated in the presence of 730 mg. of 5% palladium-on-carbon (pre-reduced in ethanol) for 2 hours under 50 psi hydrogen pressure at room temperature.
The catalyst was filtered and washed with THF and water. The com-bined washes and filtrate were evaporated and the aqueous residue was slur-ried with ethyl acetate. The pH of the slurry was adjusted to pH 3.5 and the aqueous layer was separated and washed with ethyl acetate. The aqueous layer was concentrated to a volume o~ 4 ml. and was then cooled to precip-itate 160 mg. of 7-amino-3-methoxy-3-cephem-4-carboxylic acid as a crystal-line solld.
Elemental analysis for C8HloN204S:
Theory: C, 41.73; H, 4.38, N, 12.17 Found: C, 43.45; H, 4.50; N, 12~52 I.R. ("Nujol" Mull): absorption peaks at 5.61 microns (~-lactam carbonyl).
N.M.R. (DMS0 d6): signals at 6.35 (s, 2H, C2H2), 6.20 (s, 3H, C3 metho~l), 5.30 (d, lH, C6H) and 4.94 (d, lH, C7H) tau.
U.V. (pH 7 buffer~: ~ max 268 my, =6,500.
Example 5 p-Nitrobenzyl 7-[2-(2-thienyl)acetamido]-3-methoxy-3-cephem-4-carboxylate.
To a solution of 2.4 g. o~ p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate (prepared as described in Example 3) in 50 ml. of acetone was added 1.7 g. of sodium bicarbonate. The suspension was stirred while 1.15 g.
of thiophene-2-acetyl chloride in dry acetone was added dropwise over 45 min.
After stirring for 30 min. the reaction mixture was evaporated and the residue dissolved in a mixture o~ water and ethyl acetate. The organic layer was separated, washed with water, dried and was then evaporated to a concen-' ~r r 7~3 trate. On cooling 1.9 g. of p-nitroben~yl 7-[2-(2-thienyl)acetamido]-3-methoxy-3-cephe~-4-carboxylate crystallized from the concentrate.
N.M.R. ~CDC13/DMSO d6): signals at 6.41 (s, 2H, C2H2),

6.15 (s, 2H, side-chain CH2), 6.10 (s, 3H, C3 methoxyl), 4.91 (d, lH, C6H), 4.7-4.35 (m, 3H, ester CH2, C7H), 3.1-1.7 (m, 7H, aromatic H) and 1.0 (d, lH, C7 NH) tau.
U.V. (ethanol) ~ max 260 m~, ~ =15,000 ~max 235 m~, ~ =16,200.
Example 6 p-Nitrobenzyl 7-[2-(2-thienyl)acetamido]-3-methoxy-3-cephem-4-carbo~ylate.
A. To a solution of 1.55 g. of p-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxylate hydrochloride (prepared as described in Example 1) in 30 ml. of acetone containing 364 mg. (0.5 ml., 3.6 mmole) of triethylamine was added 962 mg. of urea. With stirring at room temperature, a solution of 730 mg. (4.4 mmole) of 2-thiophene acetyl chloride in 20 ml. of acetone was added dropwise to the mixture. After 2.5 hours the reaction mixture was filtered and evaporated. The residue was dissolved in ethyl acetate and the solution was washed successively with water, a 5% solution of sodium bicar-bonate, 5% hydrochloric àcid, and a saturated solution of sodium chloride.
The washed solution was dried and then was concentrated by evaporation in vacuo to yield 1.2 g. of the reaction product as a crystalllne residue. The product was recrystallized from ethyl acetate to yield pure p-nitrobenzyl 7-; [2-(2-thienyl)acetamido]-3-hydroxy-3-cephem-4-carboxylate having the following spectral properties.
I.R. ("Nujol Mull): absorption peaks at 3.0 (amide NH), 5.68 (~-lactam carbonyl), and 6.1 (amide, and ester hydrogen ; bonded to 3 OH) microns.
N.M.R. (CDC13/DMSO d6): signals at 6.54 (2d, 2H, C2H2), 6.16 (s, 2H, side-chain CH2), 4.90 (d, lH, C6H) 4.60 (d, 2H, ester CH2) ,4.43 (q, lH, C7H), 3.1-1.6 (m, 7H, aromatic H) and 1.30 (d, lH, amide NH) tau.
B. To a solution of 2 g. of p-nitrobenzyl 7-[2-~(2-thienyl)acetamido]-.

7~3 -3-hydroxy-3-cephem-4-carboxylate in 50 ml. o~ methylene chloride was added excess diazomethane in methylene chloride and the reaction mixture l~as allowed to stand for 2 hours at room temperature. The reaction mixture was evaporated and the residue was dissolved in ethyl acetate. The ethyl acetate solution was allowed to stand in the cold for 16 hours to precipitate 750 mg.
of crystalline p-nitrobenzyl 7-[2~(2-thienyl) acetamido]-3-methoxy-3-cephem-4-carboxylate.
Elemental analysis for: C21H19N3O7S2 Theory: C, 51.53; H, 3.91; N, 8.58; S, 13.10; 0, 22.88 Fo~md: C, 51.49; H, 3.76; N, 3.49; S9 12.90; O, 23.03 Methoxyl determination:
Theory: 6.33%
Found: 6.09%.
I.R. ('~ujol" Mull): absorption peaks at 3.02 (amide NH), ; 5.65, 5.75 and 6.01 (6-lactam, and ester and amide carbonyl respectively) microns.
N.M.R. (CDC13): signals at 6.62 (s, 2H, C2H2), 6.18 (s, 3H, - C3 methoxyl), 6.16 (s, 2H, side-chain ca2), 4.98 (d, lH, C6H), 4.71 (d, 2H, ester ~l2), 4.42 (q, lH, C7H), 3.19 ~a (d, lH, amide NH) and 3.1-1.65 (m, 7H, aromatic H) tau.
U.V. (ethanol: absorption maxima:
max 237 m~u, P =15,400 max 268 m~, ~ =16,000.
Example 7 7-[2-(2-~hienyl)acetamido]~3-methoxy-3-cephem-4-carboxylic acid.
A solution containing 490 mg. of p-nitrobenzyl 7-~2-(2-thienyl)aceta-mido]-3-methoxy-3-cephem-4-carboxylate (prepared as described by Example 5 or 6), 20 ml. of THF, 60 ml. of methanol and 5 drops of lN hydrochloric acid was hydrogenated in the presence of 490 mg. of 5% Pd-on-C (pre reduced in ethanol) for 2.5 hr. under 50 psi hydrogen pressure at room temperature.
The catalyst was filtered and washed with THF and water. The combined filtrate and washes were evaporated and the pH of the aqueous residue was ~r~3l3 adjusted to pH 2.5. The residue was extracted with ethyl acetate and water was added to the extract. The pH o~ the mixture was adjusted to pH 7 and the aqueous phase was separated and slurried with ethyl acetate. The slurry was acidified to pH 2.5 and the organic layer was separated, washed with water, dried and evaporated, washed with water, dried and ev~porated to dry-ness. The residue was triturated with diethyl ether to yield 156 mg. of 7-[2-(2-thienyl)acetamldo]-3-methoxy-3-cephem-4-carboxylic acid as a crystal-line solid melting at about 168-171C. w:ith decomposition.
Elemental analysis for C14Hl~N205S2:
Theory: C, 47.45; H, 3.98; N, 7.90 Found: C, 47.52; H, 4.20; N, 7.42 N.M.R. (DMS0 d6): signals at 6.35 (s, 2~, C2H2), 6.24 (s, 5H, C3 methoxyl and side-chain CH2), 4.94 (d, lH, C6H), 4.55 (q, lH, C7H), 3.10-2.55 (m, 3H, aromatic H) and 1.10 (d, lH, amide NH) tau.
Example 8 p-Nitrobenzyl 7-(D- ~-phenyl-G~-formyloxyacetamido)-3-methoxy-3-cephem-4-carboxylate.
To a solution of 4 g. of p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-~` 20 carboxylate (prepared as described by~Example 3) in 50 ml. of acetone was added 2.8 g. of sodium bicarbonate. To the suspension was added dropwise with stlrring a solution of 2.3 g. of D- ~-formyloxy-phenylacetyl chloride in dry acetone. The acylation was complete in one hour as evidenced by thin layer chromatography.
The reaction mixture was evaporated under reduced prassure and the residue dissolved in a mixture of water and ethyl acetate. The organic layer was separated, washed with a cold 5% hydrochloric acid, dried and then evap-orated. The residual oil was slurried with diethyl ether to yield 4.8 g. of crystalline produc~.
Elemental analysis for C24H21N309S:
Theory: C, 54.~5; H, 4.01; N, 7.97 ~ound: C, 54.47; H, 4.06; N9 7.75.

~Q~7~

N.M.R. (CDC13): signals at 6.68 (s, 2H, C2H2), 6.20 (s, 3H, C3 methoxyl),~4.99 (d, lH, C6H), 4.71 (d, 2H, ester CH2), 4.48 (q, lH, C7H), 3.74 (s, lH, ~-CH), and 2.75-1.75 (m, llH, amide NH, o-formyl, and aromatic H) tau.
I.R. (~IC13): absorption peaks at 2.9 (amide), 5.58, 5.74 and 5.82 (broad, p-lactam, ester and amide carbonyls) microns.

p-Nitrobenzyl 7-(D-~ -phenyl-dformyloxyacetamido)-3-methoxy-3-cephem-4-carboxylate.
A, To a solution of 1.54 g. of p-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxylate hydrochloride (prepared as described in Example 1~ in 120 ml. of acetone and 40 ml. of water was added 936 mg. of sodium bisulfite.
With stirring a solution of 960 mg. of 0-formyl-D-mandelic acid chloride in ; 20 ml. of anhydrous acetone was added dropwise at room temperature. The reaction mixture was stirred at room temperature for 16 hours and was then evaporated to remove acetone. The aqueous residue was slurried with ethyl acetate and the organic layer separated. The extract was washed with water was dried and evaporated. The crystalline residue was triturated with di-ethyl ether and dried to yleld l g. of p~nitrobenzyl 7-(D-~ -phenyl- ~formyl-oxacetamido~-3-hydroxy-3-cephem-4-carboxylate.
Elemental analysis for C23HlgN309S:
Theory: C, 53.80; H, 3.73; N, 8.18 Found: C, 53.51; H, 3.81, N, 8.46 I.R. (CHC133: carbonyl absorption peaks at 5.55, 5.73, 5.85 and 5.93 microns.
N.~.R. (CDC13): signals at 6.61 (s, 2H, C2H2), 4.95 (d, lH, C6H), 4.61 (d, 2H, es~er CH2), 4.39 (q, lH, C7H), 3.70 (s, lH, ~-CH), and 2.80-I.70 (m, llH, amide NH and aromatic H) tau.
B. To a solution of 500 mg. of p-nitrobenzyl 7-(D- ~-phenyl-~-formy-. ~

7~:L3 loxyacetamido)-3-hydroxy-3-cephem-4-carboxylate in 20 ml. of methylene chloride was added a solution of excess diazomethane in diethyl ether. After 20 min. the mixture was evaporated and the residue was triturated with ether to provide the crystalline product, p-nitroben~yl 7-(D- ~-phenyl- dform oxyacetamido)-3-methoxy-3-cephem-4-carboxylate in a 48% yield.
Elemental analysis Eor C24H21N309S:
Theory: C, 54.65; H, 4.01; N, 7.97 Found: C, 54.43; Il, 4.23; N, 7.99.
ExamRle 10 7-(D-Mandelamido)-3-methoxy-3-cephem-4-carboxylic acid.
A solution of 528 mg. of p-nitrobenzyl 7-(D- ~ -phenyl- ~ -formyloxy-acetamido)-3-methoxy-3-cephem-4-carboxylate (prepared as described in Examples ~3 or 9) in 20 ml. of acetonitrile and 60 ml. of methanol containing 3 drops of lN hydrochloric acid was hydrogenated in the presence of 530 mg.
of 5% palladium-on-carbon (pre-reduced in ethanol) ~mder 50 psi hydrogen pressure for 2.5 hr. at room temperature~
; The catalyst was filtered and washed with T~F and water. The fil-trate and washes were combined and evaporated to remove solvents. The aqueous concentrate was slurried with ethyl acetate and the pH of the slurry was momentarily adjusted to pH 10 with lN sodium hydroxide. The pH was immediately readjusted to pH 7 with lN hydrochloric acid. The aqueous phase . . .
was separated~ washed with ethyl acetate and cooled in an ice bath. Fthyl acetate was added to the cold solution and the pH was adju~ted to pH 2.5 with lN hydrochloric acid. The ethyl acetate layer was separated and was washed with water and dried.
The dried solution was evaporated to dryness and the residue was triturated with diethyl ether to provide 115 mg. of 7-(D-mandelamido)-3-methoxy-3-cephem-4-carboxylic acid as a crystalline solid.
~lemental analysis for C16H16N206S:
Theory: Cs 52.74; H, 4.43; N, 7.69 Found: C, 52.76; H, 4.30; N, 7.46.
I.R. ("Nujol" Mull): absorption peaks at 3.0 (broad, amide NH

, ,:
~ i, ,~, `

~C376~3 and c~ ~Oh), 5.55, 5.84, 6.1 ( ~ -lactam, carboxylic acid and amide carbonyls respectively) and 6.55 (amide II band3 microns.
N.M.R. (DMSO d6): signals at 6.36 (s,2H, C2H2), 6.23 (s, 3H, C3 methoxyl), 4.98-4.45 (m, 3H, C6H side-chain CH and C7-H), 3.80 (broad s, lH, side chain OH, washed out with D20), 2.78-2.38 (m, 5H, aromatic H), and 1.45 (d, lH, amide H) tau.
Exarnple 11 7-(D-Mandelamido)-3-methoxy-3-cephem-4-carboxylic acid.
A solution of 528 mg. of p-nitroben~yl 7-(D- ~-phenyl-ct -formloxy-acetamido)-3-methoxy-3-ceyhem-4-carboxylate (prepared as described in Examples

8 or 9) in 7 ml. of acetonitrile was cooled in an ice bath and 1 ml. of con-centrated hydrochloric acid was added. Next 260 mg. of zinc dust were added portionwise with stirring and the reaction mixture was stirred in the cold for 30 min. and at room temperature for 2 hours.
The reaction mixture was poured into a mixture of water and ethyl acetate and the ethyl acetate layer was separated, washed with water and dried. The dried solution was evaporated to dryness to yield crude, 7-(D-d-phenyl- e-formyloxyacetamido)-3-methoxy-3-cephem-4-carboxylic acid.
The crude acid was dissolved~ in 15 ml. of a 5% solution of sodium -bicarbonate and the solution was extracted with ethyl acetate. The aqueous solution was allowed ~o stand for 2 hours and was then slurried with ethyl ace~ate. The slurry was cooled to 5C. and was ~acidiEied with lN hydrochloric acid to pH 2. The ethyl acetate layer was separated, washed with water, dried and evaporated to dryness. The residue was triturated with diethyl ether to obtain the reaction product, 7-(D-mandelamido-3-methoxy-3-cephem-4-carboxylic acid having spectral properties in agreement with those of the product obtained by Deblocking Method A of Example 10.
Bxan~ple 12 p-Nitrobenzyl 7- (D-mandelamido)-3-methoxy-3-cephem-4-carboxylate.
To a suspension of 365 mg. of p-nitroben~yl 7-amino-3-methoxy-3-. .

~7~

cephem-4-carboxylate (prepared as described in Example 3) in 20 ml. of ethyl acetate was added 200 mgS of mandelic O-carboxy anhydride. Next a solution of 200 mg. of sodium bisulCite in 20 ml. of water was added and the two-phase mixture was vigorously stirred for 30 min.
The ethyl acetate layer was separated, washed with water, dried and evaporated to dryness. The residue was triturated with diethyl ether to yield 350 mg. oE crystalline product.
N.~.R. (CDC13/D20): signals at 6.70 (s, 2H, C2H2), 6.22 (s, 3H, C3 methoxyl), 5.06 (d, lH, C6H), 4.90 (S9 ]H, side-chain CH), 4.75 (d, 2H, ester CH2), 4.58 (q, lH, C7H), and 2.66-1.75 (m, 9H7 aromatic H) tau.
Elemental analysis for C23H21N308:
Theory: C, 55.31; H, 4.24; N, 8.41 Found: C, 55.07; H, 4.17; N, 8~13.
Example 13 ~ethyl 7-phenoxyacetamido-3-methoxy-3-cephem-4-carboxylate.
A. A solution of 1.6 g. of methyl 7-phenoxyacetamido-3-methylene-cepham-4-carboxylate in 300 ml. of methylene chloride was cooled in an acetone-dry ice bath. Ozone was bubbled through the cold solution for three minutes at which time the reac~ion mixture developed a slight blue colora-tion. Excess ozone was expelled with a stream of oxygen and 10 g. of sodium bisulfite were added. The reaction mixture was stirred and allowed to warm ; to 0C. The liquid phase was separated by decantation and was washed succes-sively with a 5% solution of hydrochloric acid, water and a satu~ated solu-tion of sodium chloride. The washed mixture was dried and evaporated to yield 1.5 g. of crude methyl 7-phenoxyacetamido-3-hydroxy-3-cephem-4-carbox-~ ylate as an amorphous solid.
; The crude product was dissolved in ethyl acetate and was extracted with a 5% solution of sodium bicarbonate.' Ethyl acetate was added to the 3~ extract which was then acidified to pH 2 with lN hydrochloric acid. The organic phase was separated'and washed'with a saturated solution of sodium chloride and dried. I'he dried'extract was evaporated'to dryness to yield ~7~3 709 mg. of the reaction product contaiminated with a minor amount of the corresponding 3-hydroxy-3~cephemsulfQxide, an over oxidation product. The product was separated from the sulfoxide impurity and obtained pure by prep-arative thin layer chromatography on silica gel with chloroform:methanol (9:1).
Elemental analysis for: C16H16N206S.H20 Theory: C, 50.26; H, 4.75; N, 7.33; S, 8.38 Found: C, 51.03; H, 4.62; N, 7.06; S, ~.37 I.R. (chloroform): absorption peaks at 2.8 (amide NH), 5.6 (~ -lactam carbonyl), 5.85 (broad, amide and ester carbonyl and 6.6 (amide II) microns.
N.M.R. (CDC13): signals at 6.65 (s, 2H, C2-H2), 6.13 (s, 3H, methyl ester), 5.40 (s, ~H, side-chain H2), 4.93 (d, lH, C6H), 4.32 (q, lH, C7H), 3.15-2.38 (m, 6H, aromatic and amide H), and 1.60 (broad s, lH, 3-OH) tau.
Electrometric titration (66% aqueous DMF):
pKa 5.6.
; b. To a solution of 107 mg. of methyl 7-phenoxyacetamido-3-hydroxy-3-cephem-4-carboxylate in 10 ml. of methylene chloride was added excess dia-zomethane in methylene chloride. After 30 min. the reaction mixture was evaporated and the residue was dissoIved in ethyl acetate. The solution was washed with water and dried. Evaporation of the dried solution gave the product, methyl 7-phenoxyacetamido-3-methoxy-3-cephem-4-carboxylate having the following spectral properties.
I.R. (OEIC13): absorption bands at 2.9 (amide NH), 5.60 ( ~-lactam carbonyl), 5.70 (ester carbonyl), and 5.91 (amide carbonyl) microns.
N.M.R. (CDC13): signals at 6~60 (s, 2H, C2H2~, 6.20 (s, 3H, methyl ester CH3), 6~13 (s, 3H, C3 methoxyl), 5.43 (s, 2H, slde-chain CH2), 4.93 (d~ lH, C6H), 4.40 (q, lH, C7H), 3.27-2.47 (m, 5H, aromatic H) and 2.22 (d, lH, amide NH) tau.

. ~ ,,, ~7~

U.V. (ethanol); ~ max 268 mu, =7,800.
_xample 14 p-Nitrobenzyl 7~phenoxyacetamida-3-methoxy-3-cephem-4-carboxylate.
~ ollowing the etherification procedure described by Example 13, p-nltrobenzyl 7-phenoxyacetamido-3-hydroxy-3-cephem-4-carboxylate was reacted with diazonlethane to provide after crystallization from ether and warm ben-zene, crystalline p-nitrobenzyl 7-phenoxyacetamido-3--methoxy-3-cephem-4-car-boxylate.
N.M.R. (CDC13): signals at 6.62 (s, 2H, C2H), 6.20 (s, 3H, C3 methoxyl), 5.46 (s, 2H, side-chain CH2), 4.98 (d, lH, C6H), 4.72 (d, 2H, ester CH2), 4.44 (q, lH, C7H), and 3.2-1.7 (m, 10H, aromatic H and amide NH) tau.
Example 15 p-Methoxybenzyl 7-phenoxyacetamido-3-methoxy-3-cephem-4-carboxylate.
A. A solution of 2.5 g. of p-methoxybenzyl 7-phenoxyacetamido-3-methylenecepham-4-carboxylate in 350 ml. of ethyl acetate was cooled in an acetone-dry ice bath. Ozone was bubbled through the cold solution for 8 minutes and then oxygen was passed through the ozonized reaction mixture to expel excess ozone. The intermediate ozonide was decomposed by adding to 20 the reaction mixture 25 g. of sodium bisulfite with stirring at a temperature of about 0C. The reaction solution was decanted and was washed successively with water, 5% hydrochloric acid and a saturated solution of sodium chloride.
The washed mixture was dried and evaporated to yield the reaction product, p-methoxybenzyl 7-phFnoxyacetamido-3-hydroxy-3 cephem-4-carboxylate as an amorphous solid.
N.M.R. (CDG13). signals at 6.73 (s, 2H, C2H2), 6.23 (s, 3H, p-methoxy), 5.53 (s, 2H, side-chain CH2), 5.03 (d, lH, C6H), 4.8~ (s, 2H, ester CH2), 4.47 (q, lH, C7H), 3.40-2.50 ~m, 9H, aromatic H), 2.33 (d, lH, amide NH), and 1.53 '~broad s, lH, 3 OH) tau.
B. 'To a solution of 1.5 'g, of p-methoxybenzyl 7-phenoxyacetamido-3-hydroxy-3-cephem-4-carboxylate in methylene 'chloride was added' diazomethane .~
., .

7~

in methylene chloride followed by two drops of boron trifluoride etherate to catalyze the etherification. The reaction mixture was stirred at room temp-erature for 1.5 hr. and was then evaporated in ~acuo. The residue was dis-solved in ethyl acetate and the solution was washed successively with water, 5% hydrochloric acid, a 5~ solutlon oE sodium bicarbonate and a saturated solution o~ sodium chloride. The washed solution was dried and evaporated to yield 1.5 g. of crude product, p-methoxybenzyl 7-phenoxyacetamido-3-methoxy-3~cephem-4-carboxylate.
The product was purified by preparative thin layer chromatography over silica gel with a 7:3 benzene-ethyl acetate solvent system.
Elemental analysis for C24H24~2O7S:
Theory: C, 59.49; H, 4.99; N, 5.78; S, 6.62 Found: C, 59.35; H, 5.16; ~, 5.56; S, 6.68 I.R. (CHC13): absorption bands at 2.95 (amide NH), 5.6 and 5.9 (broad, ~-lactam carbonyl, and ester and amide carbonyls).
N.M.R. (CDC13): signals at 6.73 (s, 2H, C2H2), 6.23 (s, 6H, p-OCH3 and 3 OCH3), 5.45 (s, 2H, side-chain CH2), 5.00 (d, lH, C6H), 4.85 (s, 2H, ester OE12~, 4.47 (q, lH, C7H~, 3.33~2.50 (m, 9H, aromatic H) and 2.25 (d, lH, amide NH) tau.
U.V. (ethanol) ~ max 268 m~, =5,000 max 220 m~ =14 9000 .
Example 16 7-Phenoxyacetamido-3-methoxy-3-cephem-4-carboxylic acid~
To a solution of 176 mg. of p-methoxybenzyl-7-phenoxyacetamido-3-methoxy-3-cephem-~carboxylate (prepared as described in Example 15) in 10 ml. of benzene con~aining 50 mg. of anisole was added 770 mg. of trifluoro-ace~ic acid. The mixture was stirred at room temperature for 45 min. and was then evaporated in vacuo. The residual oil was dissolved in ethyl acetate and the solution washed with water. Water was added and the mixture was titrated to pH 6.5 with O.lN sodium hydroxide. The aqueous phase was separated and layered with ethyl acetate. The mixture was back titrated to pH 2.8 with hydrochloric acid in the cold. The organic layer was separated, washed with water, dried, and evaporated to dryness to yield 54 mg. of 7-phenoxy-acetamido-3-methoxy-3-cephem-4-carboxylic acid as an amorphous solid.
I.R. (CHC13): absorption peaks at 2.95 (amide NH), 5.60 (~ -lactam carbonyl), 5.89 (broad, amide and carboxylic acid carbonyl), and 6.5 (amide II) microns.
N.M.R. (CDC13): signals at 6.77 (s, 2H, C2H2), 6.13 (s, 3H, C3 methoxyl), 5.47 (s, 2H, side-chain CH2), 4.97 (d, lH, C6H), 4.50 (q, lH, C7H), 3.30-2.53 (m, 5H, aromatic H), 2.33 (d, lH, amide NH) and 1.5 (broad s, lH, C4 COOH) tau.
Example 17 p-Nitrobenzyl 7-acetamido-3-methoxy-3-cephem-4-carboxylate.
A. A solution of 10 mmole of p-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxylate hydrochloride (prepared as described in Example 1) in a mixture of 325 ml. of acetone and 125 ml. of water was cooled in an ice-water bath. With stirring a stream of ketene gas was bubbled through the solution Eor 30 minutes. Thereater the reaction mixture was evaporated to remove acetone and the aqueous residue was slurried with ethyl acetate. The ethyl acetate layer was separated and was washed with 5% hydrochloric acid and a saturated solution of sodium chloride. The washed extract was dried and evaporated in vacuo to yield the reaction product as a crystalline residue.
The residue was triturated with diethyl ether and vacuum dried to yield 3.55 g. of p-nitrobenzyl 7-acetamido-3-hydroxy-3-cephem-4-carboxylate melting at about 146-152C. with decomposîtion.
Elemental analysis for: C16H15N307S:
Theory: C, 48.85; H, 3.84; N, 10.68.
Found: C, 48.97; E, 3.96; N, 10.42.
I.R. (CHC13): absorption bands at 2.9 and 3.0 (amide NH and OH), ~0 5.63 (~ -lactam carbonyl) and 5.95 (broad, amide, and ester carbonyl hydrogen bonded to 3 OH) microns.

N.M.R. (CDC13): signals at 7.90 (s, 3H, 7-acetamido CH3~, ~7~3 6.55 (s, 2M, C2H2), 4.92 (d, lH, C6H), 4.63 (m, 2H, ester CM2), 4.3Q (~, lH, C7H), 2.81 (d, lH, amide NH), 2.5-1.8 (m, 4H, aromatic HO),and 2.8 (s, lH, C3 OH) tau.
Electrometric titration (66% aqueous DMF) pKa 5.9.
B. Following the methylation procedure described by Example 15, p-nitrobenzyl 7-acetamido-3-hydroxy-3-cephem-4-carboxylate was reacted with diazomethane to provide crystalline p-nitrobenzyl 7-acetamido-3-methoxy-3-cephem-4-carboxylate.
Elemental analysis for: C17H17N307S:
Theory: C, 50.12; H, 4,21; N, 10.31 ; Found: C, 50.09; H, 4.20; N, 10.59.
I.R. ("Nujol" Mull): carbonyl absorption at 5.64 and 5.9 microns.
N.M.R. (DMSO d6): signals at 8.05 (s, 3H, 7-acetamido CH3), 6-30 (s, 2H, C2H2), 6.10 (s, 3H, methoxyl), 4.91 (d, lH, C6H), 4.60 (s, 2Hs ester CH2), 4.53 (q, lH, C7H) and 2.4-1.8 (m, 4H, aromatic H) tau.
U.V. (ethanol) ~ max 265 m~, 2 =16,400.
Example 18 .
7-[5-(2-,4-dichlorobenzamido)-5-carboxyvaleramido]-3-methoxy-3-cephem-4-carboxylic acid dibenzhydryl ester.
~ A solution of 7-[5-(2,4-dichlorobenzamldo)-5-carboxyvaleramido]-3-; exomethylenecepham-4-carboxylic acid dibenzhydryl ester in methylene chloride is cooled to -78C. in a dry ice-acetone bath and ozone is bubbled through the mix~ure to form the ozonide.~ Thereafter the reaction mixture is purged of excess ozone by passing nitrogen through the cold mixture. The reaction mixture is then treated with excess gaseous sul$ur dîoxide to de-compose the ozonide and provide 7-[5-(294-dichlorobenzamido)-5-carboxyvaler-amido]-3-hydroxy-3-cephem-4-carboxylic acid dibenzhydryl ester.
To a solution of the 3-hydroxy diester in methylene chloride is added a solution of diazomethane in methylene chloride containing excess di--azomethane. The etherification mixture is al]owed to stand for 2.5 hours at ~, : : : ' .
,- ~ ' ' : .

~7~3 25~C. to provide the etherification product, 7-[5-(2,4-dichlorobenzamido)-5-carboxyvaleramido]-3-methoxy-3-cephem-4-carboxylic acid dibenzhydryl ester.
Example 19 Benzhydryl 7-amino-3-methoxy~3-cephem-4-carboxylate hydrochloride.
To a solution of 7-[5-(2,4-dichlorobenzamido)-5-carboxyvaleramido]-3-methoxy-3-cephem-4-carboxylic acid dibenzhydryl ester (prepared as described in Exan~le 18) in methylene chloride maintained at 0-5C. is added dry pyridine and phosphorus pentachloride in methylene chloride and the reaction mixture is stirred for 3 hours. To the cold reaction mixture is added with stirring an excess of sec-butanol. The precipitate of benæhydryl 7-amino-3-methoxy-3-cephem-4-carboxylate hydrochloride is filtered an~ can be purified by recrystallization.

.- '~:"

Claims (24)

The embodiments of the invention for which an exclusive property or privilege is claimed are defined as follows:

1. A process for preparing compounds of the formula wherein R' is hydrogen, or an acyl group of the formula wherein R' is C1-C7 alkyl, C3-C7 alkenyl, cyanomethyl, halomethyl, 4-amino-4-carboxybutyl, protected 4-amino-4-carboxybutyl; or the group R" wherein R"
is 1,4-cyclohexadienyl, phenyl, or phenyl substituted by halogen, hydroxy, nitro, amino, cyano, C1-C4 lower alkyl, C1-C4 lower alkoxy, hydroxymethyl, aminomethyl, protected aminomethyl, carboxy or carboxymethyl; or an aryl-alkyl group of the formula R"-(Y)m-CH2- wherein R" is as defined above, Y is O or S, m is 0 or 1; or a substituted arylalkyl group of the formula wherein R''' is R" as defined above, 2-thienyl or 3-thienyl, Z is hydroxy or protected hydroxy; or a heteroarylmethyl group of the formula R" "=CH2-wherein R" " is 3-thienyl, 3-thienyl, 2-furyl, 3-furyl, 2-thiazyl, 2-oxazyl, 5-tetrazyl or 1-tetrazyl; and wherein R1 is methyl or ethyl R2 is hydrogen or a carboxylic acid protecting ester forming group; and when R2 is hydrogen, the pharmaceutically acceptable nontoxic salts thereof; which comprises a) reacting a 3-hydroxy-3-cephem compound of the formula or the Keto tautomer thereof, wherein R is as defined above and R2 is a carboxylic acid protecting ester forming group, with diazomethane or diazo-ethane, in an inert solvent;
b) recovering the 3-alkoxy-3-cephem ester so obtained from the reaction mixture;
c) optionally acylating the recovered 3-alkoxy-3-cephem ester wherein R is hydrogen to provide the corresponding 7-acylamido compound wherein R is other than hydrogen; and d) optionally removing the carboxylic acid protecting ester forming group from the 3-alkoxy-3-cephem ester to provide the corresponding 3-alkoxy-3-cephem carboxylic acid.

2. Compounds of the formula wherein R is hydrogen, or an acyl group of the formula wherein R' is a) C1-C7 alkyl, C3-C7 alkenyl, cyanomethyl, halomethyl, 4-amino-4-carboxybutyl, protected 4-amino-4-carboxybutyl; or b) the group R" wherein R" is 1,4-cyclohexadienyl, phenyl, or phenyl substituted by halogen, hydroxy, nitro, amino, cyano, C1-C4 lower alkyl, C1-C4 lower alkoxy, hydroxymethyl, aminomethyl, protected aminomethyl, carboxy or carboxymethyl; or c) an arylalkyl group of the formula R"-(Y)m-CH2- wherein R"
is as defined above, Y is O or S, m is 0 or 1; or d) a substituted arylalkyl group of the formula wherein R''' is R" as defined above, 2-thienyl or 3-thienyl, Z is hydroxy or protected hydroxy; or e) a heteroarylmethyl group of the formula R" "-CH2- wherein R" " is 2-thienyl, 3-thienyl, 2-furyl, 3-furyl, 2-thiazyl, 2-oxazyl, 5-tetra-zyl or 1-tetrazyl; and wherein R1 is methyl or ethyl; R2 is hydrogen or a carboxylic acid protecting ester forming group; and when R2 is hydrogen, the pharmaceutically acceptable nontoxic salts thereof; whenever prepared by the process of claim 1 or by an obvious chemical equivalent thereof.

3. A process for preparing 7-phenoxyacetamido-3-methoxy-3-cephem-4-carboxylic acid which comprises a) reacting p-methoxybenzyl 7-phenoxyacetamido-3-hydroxy-3-cephem-4-carboxylate with diazomethane in an inert solvent;
b) recovering the p-methoxybenzyl 7-phenoxyacetamido-3-methoxy-3-cephem-4-carboxylate from the reaction mixture; and c) removing the p-methoxybenzyl carboxylic acid protecting group.

4. 7-Phenoxyacetamido-3-methoxy-3-cephem-4-carboxylic acid whenever prepared by the process of claim 3 or by an obvious chemical equivalent thereof.

5. A process for preparing 7-(D-mandelamido)-3-methoxy-3-cephem-4-carboxylic acid which comprises a) reacting p-nitrobenzyl 7-(D-.alpha.-phenyl- .alpha.-formyloxyacetamido) -3-hydroxy-3-cephem-4-carboxylate with diazomethane in an inert solvent;

b) recovering the p-nitrobenzyl 7-(D-.alpha.-phenyl-.alpha.-formyloxy-acetamido)-3-methoxy-3-cephem-4-carboxylate from the reaction mixture; and c) removing the formyl hydroxyl protecting group and the p-nitrobenzyl carboxylic acid protecting group.

6. 7-(D-mandelamido)-3-methoxy-3-cephem-4-carboxylic acid whenever prepared by the process of claim 5 or by an obvious chemical equivalent thereof.

7. A process for preparing p-nitrobenzyl 7-(D-mandelamido)-3-methoxy-3-cephem-4-carboxylate which comprises a) reacting p-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxy-late hydrochloride with diazomethane in an inert solvent;
b) recovering the p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate from the reaction mixture; and c) acylating the p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate with mandelic O-carboxy anhydride.

8. p-Nitrobenzyl 7-(D-mandelamido)-3-methoxy-3-cephem-4-carboxylate whenever prepared by the process of claim 7 or by an obvious chemical equivalent thereof.

9. A process for preparing p-nitrobenzyl 7-(D-.alpha.-phenyl-.alpha.-formylo-xyacetamido)-3-methoxy-3-cephem-4-carboxylate which comprises a) reacting p-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxy-late hydrochloride with diazomethane in an inert solvent.
b) recovering the p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate from the reaction mixture; and c) acylating the recovered p-nitrobenæyl 7-amino-3-methoxy-3 cephem-4-carboxylate with D-.alpha.-formyloxyphenylacetyl chloride.

10. A process for preparing p-nitrobenzyl 7-(D-.alpha.-phenyl-.alpha.-formyl-oxyacetamido)-3-methoxy-3-cephem-4-carboxylate which comprises a) reacting p-nitrobenzyl 7-(D-.alpha.-phenyl-.alpha.-formyloxyacetamido)-3-hydroxy-3-cephem-4-carboxylate with diazomethane in an inert solvent; and b) recovering the p-nitrobenzyl 7-(D-.alpha.-phenyl-.alpha.-formyloxy-acetamido) 3-methoxy-3-cephem-4-carboxylate from the reaction mixture.

11. p-Nitrobenzyl 7-(D-.alpha.-phenyl-.alpha.-formyloxyacetamido)-3-methoxy-3-cephem-4-carboxylate whenever prepared by the process of claims 9 or 10 or by an obvious chemical equivalent thereof.

12. A process for preparing p-nitrobenzyl 7-[2-(2-thienyl)acetamido]
-3-methoxy-3-cephem-4-carboxylate which comprises a) reacting p-nitrobenzyl 7-[2-(2-thienyl)acetamido]-3-hydroxy-3-cephem-4-carboxylate with diazomethane in an inert solvent; and b) recovering the p-nitrobenzyl 7-[2-(2-thienyl)acetamido]-3-methoxy-3-cephem-4-carboxylate from the reaction mixture.

13. A process for preparing p-nitrobenzyl 7-[2-(2-thienyl)acetamido]
-3-methoxy-3-cephem-4-carboxylate which comprises a) reacting p-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxy-late hydrochloride with diazomethane in an inert solvent;
b) recovering the p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate from the reaction mixture; and c) acylating the recovered p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate with thiophene-2-acetyl chloride.

14. p-Nitrobenzyl 7-[2-(2-thienyl)acetamido]-3-methoxy-3-cephem-4-carboxylate whenever prepared by the process of claims 12 or 13 or by an obvious chemical equivalent thereof.

15. A process for preparing 7-[2-(2-thienyl)-acetamido]-3-methoxy-3-cephem-4-carboxylic acid which comprises a) reacting p-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxy-late hydrochloride with diazomethane in an inert solvent;
b) recovering the p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate from the reaction mixture;
c) acylating the recovered p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate with thlophene-2-acetyl chloride; and d) removing the p-nitrobenzyl carboxylic acid protecting group.

16. 7-[2-(2-thienyl)acetamido]-3-methoxy-3-cephem-4-carboxylic acid whenever prepared by the method of claim 15 or by an obvious chemical equiv-alent thereof.

17. A process for preparing p-nitrobenzyl 7-amino-3-methoxy-3-cephem -4-carboxylate which comprises a) reacting p-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxy-late hydrochloride with diazomethane in an inert solvent; and b) recovering the p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate from the reaction mixture.

18. p-Nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate whenever prepared by the process of claim 17 or by an obvious chemical equivalent thereof.

19. A process for preparing 7-amino-3-methoxy-3-cephem-4-carboxylic acid which comprises a) reacting p-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxy-late hydrochloride with diazomethane in an inert solvent;
b) recovering the p-nitrobenzyl 7-amino-3-methoxy-3-cephem-4-carboxylate from the reaction mixture; and c) removing the p-nitrobenzyl carboxylic acid protecting group.

20. 7-Amino-3-methoxy-3-cephem-4-carboxylic acid whenever prepared by the process of claim 19 or by an obvious chemical equivalent thereof.

21. A process for preparing p-nitrobenzyl 7-acetamido-3-methoxy-3-cephem-4-carboxylate which comprises a) reacting p-nitrobenzyl 7-acetamido-3-hydroxy-3-cephem-4-carboxylate with diazomethane in an inert solvent, and b) recovering the p-nitrobenzyl 7-acetamido-3-methoxy-3-cephem-4-carboxylate from the reaction mixture.

22. p-Nitrobenzyl 7-acetamido-3-methoxy-3 cephem-4-carboxylate whenever prepared by the process of claim 21 or by an obvious chemical equivalent thereof.

23. A process for preparing benzhydryl 7-amino-3-methoxy-3-cephem-4-carboxylate hydrochloride which comprises a) reacting 7-[5-(2,4-dichlorobenzamido)-5-carboxyvaleramido]-3-hydroxy-4-carboxylic acid dibenzhydryl ester with diazomethane in an inert solvent:

b) recovering the 7-[5-(2,4-dichlorobenzamido)-5-carboxy-val-eramido]-3-methoxy-4-carboxylic acid dibenzhydryl ester from the reaction mixture; and c) cleaving the 5-(2,4-dichlorobenzamido)-5-carboxyvaleryl side chain by reaction with phosphorus pentachloride.

24. Benzhydryl 7-amino-3-methoxy-3-cephem-4-carboxylate hydro-chloride whenever prepared by the process of claim 23 or by an obvious chemical equivalent thereof.