CA1070673A - 7.beta.-(2-ARYL-2-(ETHERIFIED OXIMINO) ACETAMIDO) -3-N-SUBSTITUTED CARBAMOYLOXYMETHYLCEPH-3-EM-4-CARBOXYLIC ACIDS - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Cephalosporin antibiotics in which the 7.beta.-acylamido group is syn 2-aryl-2-(etherified imino) acetamido and in which the 3-position substituent is an alkyl-, alkenyl-etc substituted carbamoyloxymethyl group exhibit high antibacterial activity against a broad range of gram positive and gram negative organisms, particularly high stability to .beta.-lactamases produced by various organisms, and stability in vivo. The compounds are syn isomers or exist as mixtures of syn and anti isomers containing at least 90% of the syn isomer.

Description

10706~3 This invention is concerned with improvements in or relating to antibiotics of the cephalosporin series.
The cephalosporin compounds in this specification are named with reference to "cepham" after J.Amer. Chem.
Soc., 1962, 84, 3400, the term "cephem" referring to the basic cepham structure with one double bond.
Many cephalosporin compounds possessing a degree of antibacterial activity are known in the art, these com-pounds possessing ~3 unsaturation and ordinarily being substituted at the 3-position by a methyl or substituted methyl g~ up and at the 7~-position by an acylamido group.

It is now well recognised that the antibiotic properties of a particular ceph-3-em-4-carboxylic acid are predomin-antly controlled by the nature of both the 7~-acylamido group thereof and the 3-position substituent which the compound carries; considerable research has been undertaken to find combinations of such groups which will yield anti-biotics with particular properties.
Cephalosporin antibiotics are widely used in the treat-ment of diseases caused by pathogenic bacteria in human beings and animals, for example in the treatment of ~. ' ' ~070673 diseases caused by bacteria which are resistant to other antibiotics such as penicillin compounds and in the treatment of penicillin-sensitive patients. In many appli-cations it is desirable to employ a cephalosporin antibiotic which exhibits activity against both gram positive and gram negative microorganisms, and a significant amount of re-search has been directed to the development of improved -broad spectrum cephalosporin antibiotics.
The practical utility of a significant number of known commercial and experimental cephalosporin anti-biotics is limited by their relatively high suscepti-bility to the ~-lactamases which are produced by many bacteria. A desirable property of a broad spectrum cephalosporin antibiotic is therefore that it should exhibit substantial resistance to ~-lactamases, including those produced by gram negative microorganisms.

A further difficulty with many cephalosporin anti-biotics intended for therapeutic applications is that they are subject to degradation in vivo. Thus a signifi-cant member of known cephalosporin antibiotics - , . . . ~ ;. ............... ,, :
: . .... ,.. ~... . .

have been found to suffer the dîsadvantage that following administration they are deactivated, often rapidly, by enzymes (e.g. esterases) present in the body.
As a result of prolonged studies of numerous cephalo-sporin ~ompounds we have now found a class of cephalo-sporin antibiotics having a particular combination of 7~-acylamido group and 3-position substituent which endows the compounds with good broad spectrum activity coupled with the above-described desiderata of high ~-lactamase stability and good stability.in vivo.
The present in~ention, therefore, provides antibiotic compounds of the general formula H H
R.C.CONH ~ S ~ .
ORa ~ ~ CH20.CO.NH.RS (I) COOH

~070673 (where R represents a furyl, thienyl or phenyl group;
Ra represents a Cl-C4 alkyl group, a C2-C4 alkenyl group, a C3-C7 cycloalkyl group or a phenyl group :
and R represents a Cl-C4 alkyl group, a C2-C4 alkenyl group, a C3-C7 cycloalkyl group, a benzyl group or a phenyl group) and non-toxic derivatives thereof, the compounds being syn isomers or existing as mixtures of ~y~ and anti isomers containing at least 90% of the syn isomer. Most preferably the compounds are syn isomers essentially free from the corresponding anti isomers.
The compounds of the present invention are defined as having the syn (cls)- isomeric form as regards the configuration of the group ORa with respect to the carboxamido group. In this specification the syn configuration is structurally defined thus R.C.CONH ~ .
1¦ (Ia) N

\

The syn configuration is assigned on the basis of the ~ork of Ahmad and Spenser n Can. J. Chem 1961, 39, 1340 , - ,' : ~ . .... .. .

. - ~

~070G73 The term "non-toxic" as applied to derivatives of the compounds of the invention means those derivatives which are physiologically acceptable in the dosage at which they are administered. Such derivatives may include, for example, salts , biologically acceptable esters ,l-oxides and solvates (especially hydrates).
Salts which may be formed, where applicable, from the compounds according to the invention include inorganic base salts such as alkali metal, e.g. sodium and potassium, alkaline earth metal e.g. calcium, and organic base, e.g.
procaine, phenylethylbenzylamine, dibenzylethylenediamine, ethanolamine, diethanolamine, triethanolamine and N-methylglucosamine,salts. The salts may also be in the form of resinates, formed e.g. with a polystyrene resin or cross-linked polystyrene divinylbenzene copolymer resin con'aining amino or quaternarv amino groups.
When R in the above formul~ I is a furyl group it may be fur-2-yl or fur-3-yl and where it is a thienyl group it may be thien-2-yl or thien-3-yl. Preferably the 1070673 ~

the group R is a fur-2-yl group.
As indicated above, the group Ra in formula I
represents an alkyl group containing 1-4 carbon atoms e.g. a methyl or ethyl group; an alkenyl or alkynyl group containing 2-4 carbon atoms, e.g. vinyl, allyl or propargyl; a cycloalkyl group containing 3-7 carbon atoms, e.g. a cyclopentyl group; or a phenyl group.
The group Rs in formula I may, where the definition so permits,bethe same AS or~ifferent from the group Ra.
It may represent an alkyl group containing 1-4 carbon atoms e.g. a methyl or ethyl group; a C2-C~ alkenyl group e.g. a vinyl or allyl group; a C3-C7 cycloalkyl group e.g. cyclopentyl.
Preferably the group R is a fur-2-yl group and the group R is a methyl group.
The ~ntibiotic compounds of the invention are characterized by their high antibacterial activity against a range of gram-positive and gram-negative organisms, their particularly high stability to ~-lactamases produced by various gram negative organisms, which properties may render them useful in the treatment of a variety of diseases caused by pathogenic bacteria in , human beings and animals.
An important compound falling within general formula ; I by virtue of its broad spectrum antibiotic properties;
stability in the presence of human serum; high stability to ~-lactamases produced by a variety of organisms; and resistance to the action of mammalian esterases is (6R,7R)-7-~2-(fur-2-yl)-2-methoxyiminoacetamido]-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid (syn isomer), having the formula `' ~ \ ~ CONH ~ ~

~OCH ' CH2O.CO,NHCH3 (II) ` for example as its sodium or potassium salt.
The compounds according to the invention may be pre-pared by any convenient method.
According to one embodiment of the invention we provide a process for the preparation of an antibiotic , 1070673 ~

~ompound of general formula I (as hereinbefore defined) and non-toxic,derivatives thereof which : .
comprises either (A) condensing a compound of the formula N2~ ~ 1 C~20.CO.NH.R~ (III) O
COOR
(wherein B is> S or~ S-~O, Rl is hydrogen or a carboxyl blocking group, Rs has the above-defined meaning, and the dott,ed line bridging the 2-, 3- and 4- positions of formula (II) indicates that the compound may be a ceph-2-em or ceph-3-èm compound) or an acid addition salt or N-silyl derivative there-of with an acylating agent corresponding to the acid:-R.C.COOH 1--' 11 \ OR tIV) i (wherein R and Ra haye the above-defined meanings) or with an acylating~agent corresponding to an acid ~, of formula R.CO.COOH (where R is as defined above);
or (B) reacting a compound of the formula i .
_ g _ .

.

.. . . .
- : - : ' . . ~ : ' ' H H

Acyl.NH j ~ B
~cH2oH (V) COOR
(wherein Acyl is the group R.C.CO or the group R . CO . CO, N
\ORa ,, s, Rl and the dotted line have the above meanings) with an isocyanate of the formula Rs NCO (wherein Rs has the above defined meaning) whereafter, if necessary and desired in each instance, any of the following reactions (C), in any appropriate sequence, are carried out (i) conversion of the pre-cursor group R.CO.CO into the desired R.C.CO-\ORa group, (ii) conversion of a ~2 isomer into the desired ~3 isomer, (iii) removal of any carboxyl blocking groups, and (iv) reduction of a compound in which B is >S~ O to form the desired R=~S compound;
and (D) recovering the desired compound of ~070673 formula (I), after separation of syn and anti isomers if necessary, and if desired after conversion of the compound to a non-toxic derivative thereof.
Where Rl is a carboxyl blocking group it may be the residue of an ester-forming alcohol (aliphatic or arali-phatic), phenol, silanol or stannanol or a symmetrical or mixed anhydride group derived from an appropriate acid.
Non-toxic derivatives of formula I may be formed in any convenient way. For example base salts may be formed by reaction of the cephalosporin acid with sodium or potassium 2-ethylhexanoate. Biologically acceptable ester derivatives may be formed using conventional ester-ifying agents. l-Oxides may be formed by treatment of the ; corresponding cephalosporin sulphide with an appropriate oxidising agent, for example, with a peracid such as metaperiodic, peracetic, monoperphthalic or m-chloro-perbenzoic acid or with t-butyl hypochlorite, conveniently in the presence of a weak base such as pyridine.
One may condense an acylating agent corresponding to the acid of formula (IV) with an amino compound of formula (III) where B and the dotted line have the above defined meanings and Rl is hydrogen or a carboxyl block-~0706~3 -ing group or a derivative thereof, e.g., a salt such as a tosylate or an N-silyl derivative, the condensation op-tionally being effected in the presence of a condensation agent, and being followed, if necessary, by removal of a carboxyl blocking group R .
Compounds of formula I may thus be prepared by employing as the acylating agent an acid halide, particu-larly an acid chloride or bromide, corresponding to the acid (IV). Such acylations may be effected at temper-atures of from -50 to +50C, preferably -20 to +30C.
The acylation may be effected in aqueous or non-aqueous media.
Acylation with an acid halide may be effected in the presence of an acid binding agent, e.g., a tertiary amine such as triethylamine or dimethylaniline, an inorganic base such as calcium carbonate or sodium bicarbonate, or an oxirane, which serves to bind hydrogen halide liberated in the acylation reaction. Where an oxirane is employed for this purpose this is preferably a lower-l, 2-alkylene oxide such as ethylene oxide or p~opylene oxide.
The free acid form of a compound of formula (IV) may itself be used as the acylating agent. Such acylations 1()70673 are desirably conducted in the presence of, for example, a carbodiimide such as N,N'-diethyl-, dipropyl- or diisop-ropylcarbodiimide, N,N'-dicyclohexyl-carbodiimide, or N-ethyl-N'- dimethylaminopropylcarbodiimide; a carbonyl com-pound such as carbonyldiimidazole; or an isoxazolinium salt such as N-ethyl-5-phenylisoxazolinium-3'-sulphonate or N-t-butyl-5-methylisoxazolinium perchlorate. The con-densation reaction is desirably effected in an anhydrous reaction medium, e.g. methylene chloride, dimethylformamide or acetonitrile.
Acylation may also be effected with other amide-form-ing derivatives of the free acid (IV) such as, for example, a symmetrical anhydride or mixed anhydride, e.g. with pival-ic acid or formed with a haloformate such as a lower alky-lhaloformate. The mixed or symmetrical anhydrides may be generated in situ. For example, a mixed anhydride may be generated using N-ethoxycarbonyL-2-ethoxy-1,2-dihydroquino-line.,~Mixed anhydrides may also be formed with phosphorus acids (for example phosphoric or ph~sphorousacids3, sulph-uric acid or aliphatic or aromatic sulphonic acids (for example ~-toluenesulphonic acid).

_ 13 ~

If desired, one can first prepare a compound of formula H H
R . CO . ca . Nll oJ "N~CH20.CO.NH.R
COORl (VI) (where B, R, R , Rs and the dotted line have the above ; defined meanings) and then effect reaction of the compound formula (V) with an etherified hydroxylamine of formula Ra O.N~2 (Ra having the above defined meaning), followed, if necessary, by removal of the group Rl. The reaction : product may be separated to give the required svn isomer before or after removal of Rl.

: The reaction of the 3-hydroxymethyl cephalosporin (V) with the isocyanate of formula R .NCO (wherein R has the above defined meaning) ~ . .

~070673 is preferably effected in the presence of a lower (Cl-C4) trialkylamine. The reaction may be effected at a temperature in the range -50 to +105C, ~onveniently from 0 to - -+25C. The reaction may be effected in a substantially inert organic solvent eg. an N,N-disubstituted amide, a ~ 5 halogenated hydrocarbon or an ether. Reactions of this ; type are described for example in United States Patent No. 3,355,452.
3-Hydroxymethyl starting material for use in the process of this embodiment of the invention may be prepared by, for example, the methods described in British Patent No. 1,121,308, and Belgian Patent No. 783,449.
As indicated above, starting materials of formula ; -IIImay if desired be employed in the form of acid addition salts, e.g. with hydr-ochloric, hydrobromic, sulphuric, nitric, phosphoric, toluene-~-sulphonic or methane sulphonic acids.
Any blocking group substituting the 4-carboxy group ` of compounds of formula III,V or VI is desirably a group which may readily be split off at a later stage of a "~ .
~ -15 _ ; ' .. . . . - , , .
.. .. .

reaction sequence and advantageously is a group contain-ing 1-20 carbon atoms. Suitable b~locked carboxyl groups are well known in the art, a list of representative groups being included in our aforementioned Belgian Patent No.
783,449. Preferred blocked carboxyl groups include aryl lower alkoxycarbonyl groups such as ~-methoxybenzyloxy-carbonyl, p-nitrobenzyloxy carbonyl and diphenylmethoxy-carbonyl; lower alkoxycarbonyl groups such as t-butoxy-carbonyl; and lower haloalkoxycarbonyl groups such as

2,2,2-trichloroethoxycarbonyl. The carboxyl blocking group may subsequently be removed by any of the appropriate methods disclosed in the literature; thus, for example, acid or base catalysed hydrolysis is applicable in many cases, as are enzymically catalysed hydrolyses.
Where at the end of a given preparative sequence compounds are obtained wherein B is~ S ->0 and a compound is desired in which B is~ S, conversion to a sulphide may for example, be effected by reduc,tion of the corresponding acyloxysulphonium or alkyloxysulphonium salt prepared in situ by reaction with e.g. acetyl chloride in the case _16_ 107~673 of an acetoxysulphonium salt, reduction being effected by, for example, sodium dithionite or by iodide ion as in a solution of potassium iodide in a water miscible solvent e.g. acetic acid, tetrahydrofuran, dioxan, dimethylformamide or dimethylacetamide. The reaction may be effected at a temperature of -20 to +50C.
Where the resultant compound is a ceph-2-em-4-carboxylic ester the desired ceph-3-em compound may be obtained by ; treatment of the former with a base.
The antibiotic compounds according to the invention may be formulated or administration in any convenient way, by analogy with other antibiotics and the invention there-fore, includes within its scope a pharmaceutical composition comprising an antibiotic compound of formula I or a non-toxic derivative e.g. salt or biologically acceptable ester thereof adapted for use in human or veterinary medicine.
Such compositions may be presented for use in conventional manner with the aid of any necessary pharmaceutical carriers or excipients.

_ lZ

.

The antibiotic compounds according to the invention may be formulated for injection and may be presented in unit dose form in ampoules, or in multidose containers with an added preservative. The compositions may take such forms as suspensions, solutions, emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilising and/or dispersing agents. Alter-natively the active ingredient may be in powder form for re-constitution with a suitable vehicle, e.g. sterile, pyrogen-free water before use.
For veterinary medicine the compositions may, for example, be formulated as intramammary preparations in ether long acting or quick-release bases.
In general the compositions may contain from 0. l~/o upwards, preferably from 10-60% of the active material;
depending on the method of administration. Where the compositions comprise dosage units, each unit will prefer-ably contain 50-1500 mg. of the active ingredient. The dosage as employed for adult human treatment will prefer-ably range from 500 - 4000 mg. per day, depending on the _ 18-- - . . . . .
. .
, .

route and frequency of administratinn.
The compounds according to the invention may be administered in combination with other compatible thera-peutic agents such as antibiotics, for example penicillins, other cephalosporins or tetracyclines.
The following examples illustrate the invention. All temperatures are in C. Melting points were determined on a Kofler block for Examples 1-6; for Examples 7-13 melting points were determined in open-ended capillaries on a Mettler apparatus a~nd take the form (My3 where x is the rate of heating in C per minute and y is the insertion temperature. Rotations were measured in the temperature range 18-24C. Ultra-violet spectra were measured in pH6 phosphate buffer. Structures were also confirmed by infrared and proton magnetic resonance spectropscopy.

.:

Example 1 (6R,7R)-7-~2-(Fur-2-yl)-2-methoxyiminoacetamido~-3-N-phenylcarbamoyloxvmethvlceph-3-em-4-carboxvlic Acid ~syn isomer) A solution of (6R,7R)-7-[2-(fur-2-yl)-2-methoxy-iminoacetamido]-3-hydroxymethylceph-3-em-4-carboxylic acid (syn isomer) (l.OOg) in N,N-~tbyl-formamide (20ml, purified by filtration through basic alumina) was cooled to 5 and was treated with triethyl-amine (0.73ml) and phenyl isocyanate (2.85ml).
The reaction was stirred for 1 hour at 5 when the ice-bath was removed and stirring continued for 1.5 hours at ca. 20 . The solution was partitioned between aqueous sodium bicarbonate solution (3%, lOOml) and ethyl acetate (lOOml). The layers were separated and the aqueous solution was washed with ethyl acetate (3xlOOml), then covered with ethyl acetate (lOOml) and acidified to pH 1.8 with concentrated hydrochloric acid.

The layers were separated and the aqueous layer extracted with further ethyl acetate (4xlOOml). The combin-ed organic extracts were washed with water (5xl50ml) and saturated sodium chloride solution (lOOml) and dried (MgS04), and the solvent was removed in vacuo to give a yellow froth which was t~iturated with ether (50ml) to give the title compound ~905mg) [a]D + 27 (c 1, DMSO) AP max 255nm (~ 23,500) and 270nm (19,500) Example 2 Sodium (6R,7R)-7-L2-(Fur-2-yl)-2-methoxyiminoacetamido]-

3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylate(syn isomer) Treatment of (6R,7R)-7-[2-(fur-2-yl)-2-methoxy-iminoacetamido]-3-hydroxymethylceph-3-em-4-carb~xylic acid (syn isomer) (1.525g~ i~ N,N-dimethylformamide (60ml) with triethylamine (1~12ml~, and methyl isocyanate (2.0ml~ as in Examplç 1, gave (6R,7R)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid (syn isomer) (0.803g). Part of this (0.726g) .

107~)673 was dissolved in ac.etone.(2ml) and a solution of sodium DL-2-ethylhexanoate (1.66mmole) in acetone (1.6ml) was added and the solution refrige.rated overnight. The product was filtered off, washed with chilled acetone and dried in vacuo to give the title compound (282mg) [a]D +

59 (C 1,H20); A max 274nm (~ 17,600) Example 3 (6R,7R) 3-(N-Ethylcarbamoyloxymeth~ 7--[2-(fur-2-yl)-2-methoxyiminoacetamido~ceph-3-em-4-carboxylic Acid(syn isomer) Reaction of (6R,7R)-7-~2-(fur-2-yl)-2-methoxy-iminoacetamido]-3-hydroxymethylceph-3-em-4-carboxylic acid (syn isomer) (1.54g) in N,N-dimethylformamide (60ml) with ethyl isocyanate (2.0ml) and triethylamine (1.12ml) as in Example 1 gave the .-title compound (622mg? ~a]D + 68 (C 1, DMS0); .~
A max 273nm (E 16,350). :

.

Example 4 (6R.7R)-3-(N-t-ButylcarbAmoyloxymethv1-7-~2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic Acid (syn isomer) Reaction of (6R,7R)-7-[2-(fur-2-yl)-2-methoxyimino-acetamido]-3-hydroxymethylceph-3-em-4-carboxylic acid (syn isomer) (2.00g) in N,N~d~G~hy~f3r~E~de (60ml) with t-butyl isocyanate (5.20g) and triethylamine (2.92ml) as in,Example 1, gave the title comPound (1.58g) [a~D + 77(c 1, DMS0);

AP max 275nm (~ 16,400).
Exam~e~e 5 (6R,7R)-3-(N-Allylcarbamoyloxymethyl)-7-~2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic Acid (syn isomer) Treatment of (6R,7R)-7-[2-(fur-2-yl)-2-methoxyimino-acetamido]-3-hydroxymethylceph-3-em-4-carboxylic acid (syn isomer) (2.00g~ in N,N-dimethylformamide (lQQ~l) with triethylamine (2.0ml) and allyl isocyanate (4.42g) as in Example 1, afforded the ' . : : , ' :'- . : ' -.

10 ~0 6~ 3 title compound (1.63g,~ ~]D +32(c 1, l,DMSO~, ~P max 274nm (~ 13,100).
Example 6 (6R,7R)-7-[2-(Fur-2-vl)-2-methoxyiminoacetamido]~3~N~
methylcarbamoyloxymethylceph-3-em-4-carboxylic Acid syn isomer) A suspension of (6R,7R)-7-[2-(fur-2-yl)-2-methoxyimino-acetamido]-3-hydroxymethylceph-3-em-4-carboxylic acid ~yn isomer)(l.OOg) in dry dichloromethane (50 ml,) was treated with tri-n-butyl tin oxide (0.871 g) and stirred under nitrogen for 30 minutes at 21, during which time the suspension dissolved. Methyl isocyanate (0.60 g., 10.50 mmole) was added, and stirring continued for a further 3 hours. Ethyl acetate (30 ml.) and water ~30 ml.) were added and the dichloromethane removed in vacuo.
The volume of ethyl acetate was made up to ca. 30 ml. and the pH of the solution adjusted to 8.5 with aqueous sodium bicarbonate solution. The aqueous solution was washed with ethyl acetate (3 x 30 ml.) then covered with further ethyl acetate (30 ml.) and adjusted to pH 1,9 with hydrochloric acid. The phases were separated and the aqueous phase extracted with fur~ar ethyl acetate (3 x 50 ml.) . ., ~ , .' ' ~ : .

10'70673 The combined ethyl acetate extracts were washed with saturated sodium chloride solution and dried (magnesium sulphate) and the solvent removed in vacuo to give the title carboxYlic acid as an off-white froth (0.962 g);
[a]D + 47 (c 0.57, DMSO); ~max 273nm ( 15, 450).
Example 7 B j ~_~
acetamido]ceph-3-em-4-carboxylic Acid (sYn isomer) A suspension of (6R,7R)-3-hydroxymethyl-7-~2-methoxy-imino-2-(fur-2-yl)acetamido]ceph-3-em-4-carboxylic acid (syn isomer) (l.OOg) in dry benzene (SOml) under nitrogen was treated with tri-n-butyl tin oxide (0.870g) and solution was obtained after stirring for 30 minutes.
lS Cyclohexyl isocyanate (1.318g) was added and stirring was continued for a further 3~ hours by which time the reaction was essentially complete.
Addition of water (50ml) to the reaction mixture caused the precipitation of dicyclohexylurea (which was filtered off). The benæene layer was separated, s~irred and O.lM hydrochloric acid (50ml? was added to give a white gelatinous precipitate which was filter~d off.

' .

-The precipitate was dissolved in aqueous sodium bicarbonate solution which was extracted with ethyl acetate (SOml).
The aqueous phase was acidified with 2M-hydrochloric acid and extracted with ethyl acetate (2x80ml). The organic layer was washed with water (2xlSOml), dried over magnesium S sulphate and evaporated in vacuo to yield the title compound (396mg) as an off-white solid, m.p. (M80) 162,, [a]20-5 +
38.0, (cl.03,dioxan),~max (pH6 phosphate ~uffer)274nm ~s16,~
Example 8 (6R,7R)-3-N-n-Butylcarbamoyloxymethyl-7-~2-methoxyimino-2-(fur-2-yl)acetamido~ceph-3-em-4- ~ lic Acid (sYn isomer) A suspension of (6R,7R)-3-hydroxymethyl-7-[2-methoxy-imino-2-(fur-2-yl)acetamido~ceph-3-em-4-carboxylic acid (syn isomer) (2.00g) in dry benzene (under nitrogen) was treated with tri-n-butyl tin oxide (1.74g) and solution 15-i was obtained after stirring for 1 hour. n-Butyl isocyanate (2.08g) was added and stirring was continued for a further

4 hours. Water (lOOml) was added to the reaction mixture and the stirred separated benzene layer was treated with O.lM hydrochloric acid (lOOml) to deposit a gelatinous ... : . . : ~
. .
': '. ' . ,:

precipitate which was filtered off and dissolved in aqueous saturated sodium bicarbonate solution (lOOml).
After washing the aqueous solution with ethyl acetate (2xlOOml) the aqueous phase was acidified with 2M hydro-chloric acid under an ethyl acetate layer (lOOml). The organic phase was separated and the aqueous layer was re-extracted with ethyl acetate (lOOml). The combined organic extracts were washed with water (2x200ml), dried over magnesium sulphate and evaporated in vacuo to yield the title comPound (1.124g) as a pale yellow solid, m.p.(M80) 149.6, [a]20 5 + 42.6 (c 1.03, DMSO), AmaX (pH6 phosphate buffer) 274nm (~ 16,960).
Example 9 (6R.7Rj-7-[2-Methoxvimino-2-(thlen-2-yl)acetamidol-3-N- '.
methylcarbamoyloxvmethvlceph-3-em-4-carboxYlic Acid (syn isomer) A solution of 2-methoxyimino-2-(thien-2-yl)acetic acid (s~m isomer) (926mg) in dry dichloromethane (30ml) was cooled to ca 0 (under dry nitrogen).
This solution was stirred (at ca 0) with triethyl-amine (0 7ml~, oxalyl chloride (0.43ml) and dry N,N

dimethylformamide (1 drop) for 1,25 hours during which time mild effervescence and decolouration occurred.
The solution was evaporated and dried in vacuo 1.25 hours to give the corresponding acid chloride as ;
off white crystals.
A solution of the acid chloride (ca 5mmole) in dry ;~
acetone (SOml) was added dropwise over 15 minutes (at ca 1C) to a solution of (6R,7R)-7-amino-3-N-methyl-carbamoyloxymethylceph-3-em-4-carboxylic acid (862mg) and sodium hydrogen carbonate (756mg) in water (60ml) and the reaction mixture was stirred for a further 1.25 hours by which time reaction was complete (by t.l.c.).
The solution (at ca pH 7) was washed with ethyl acetate (3xlOOml) and the combined washings back-extrac-ted with water (2x50ml).
The aqueous phase was layered with ethyl acetate (150ml) and acidified to pH 1.9 with concentrated hydro-chloric acid. The aqueous phase was extracted with further ethyl acetate (2xlOOml), the organic extracts were combined, washed with water (2xl50ml), saturated brine (75ml), dried(magnesium sulphate) and evaporated -- , , ~ : ', .

~n vacuo to give a semi-crystalline white solid (1.503g).
Trituration of the crude product with ether (30ml) afforded the title compound (863mg), as a white solid m.p. (M80) 144, [a]D +57.3 (c 1.14, DMSO), ~max (pH6 phosphate buffer) 263nm ( 16,300) with an inflection at 295nm (f 10,650).
Example 10 (6R 7R)-7- r 2-EthoxYimino-2-phenvlacetamido]-3-N-methyl-~ .
carbamoYloxYmethvl-ceph-3-em-4-carboxylic Acid (sYn isomer) The method of preparation of this compound was similar to that described in Example 9 except that the acid chloride was made from 2-ethoxyimino-2-phenylacetic acid (syn isomer)~61mg) and the crude acid chloride was isolated as a yellow crystalline solid.
Dropwise addition of the acid chloride in dry acetone (28ml) to a solution of (6R,7R)-7-amino-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid (500mg) and sodium hydro~e~ carbonate carbQnate (43~mg) in water (35ml) at ca 10 over 10 minutès and subsequent stirring at 5 to 10 for 3~ hours resulted in the acylation of - \

~070673 the amino compound (as evidenced by tlc) The reaction mixture was then worked up in a manner substantially similar to that of Example 9 to afford the title compound (480mg) as a white powder m.p. (M82o) 138, [a]22 ~58.0 (c 1.0, DMS0), ~ (pH6 phosphate buffer) 259nm ;
( 20,150).
Example 11 (6R.7R)-3-N-methylcarbamovloxymethyl-7- r 2-phenoxyimino-2-phenylacetamido]ceph-3-em-4-carboxylic acid (sYn isomer) : ':
The acid chloride of 2-phenoxyimino-2-phenylacetic acid (sYn isomer) (700mg) was prepared in the same manner as that described in Example 9 The crude acid chloride was isolated as a pale brown gum. -A solution of this crude acid chloride in dry acetone (28ml) was added dropwise to a cooled (10) solution of (6R,7R)-7-amino-3-N-methylcarbamoyloxymethyl-ceph-3-em-4-carboxylic acid (500mg), water (35ml) and sodium hydrogen carbonate (439mg) aver 10 minutes and reaction was complete (by tlc) after stirring for 3 hours at 5 to 10. The reaction mixture was then worked up in a manner substantially similar to that of Example 9 to ., , , ~ . .

~070673 afford the title compound (453mg) as a white powder, m.p. (M82o) 165, [~]D4 ~78.8 (c 1.23, DMS0), ~max (pH6 phosphate buffer) 260nm (~ 20,050) with inflections at 265.5 nm ( 18,685) and 282nm (E 13,300).
Example 12 (6R,7R)-7- r 2-Cvclopentvloximino-2-(fur-2-vl)acetamido]-3-~.
N-methvlcarbamoyloxvmethylceph-3-em-4-carbox~lic Acid (svn isomer) The precedure adopted for the preparation of the acid chloride was similar to that adopted for Example 9 except that 2-cyclopentyloximino-2-(fur-2-yl)acetic acid (svn isomer) (556mg) was employed as the starting acid. The acid chloride was subsequently isolated as a crystalline solid.
A solution of the above acid chloride in dry acetone (25ml) was added dropwise (at ca 10) to a solution of ; (6R,7R)-7-amino-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid (500mg) and sodium hydrogen carbonate (439mg) in water (35ml) over a period of 10 minutes.
After allowing the reaction to continue for 2 hours at 5 to 10 tlc indicated that reaction was complete. The reaction 1070673 ;

mixture was worked up in a manner substantially similar to that of Example 9 to afford the title compound (608mg) as a white powder, m.p. (M 80) 126, [a~D +68.50 (c 1,06, DMS0), ~ma~(pH6 phosphate buffer) 276.5nm (~ 19,400).
Example 13 (6R,7R)-3-N-methylcarbamoyloxymethyl-7-[2-methoxyimino-2-(fur-2-yl)acetamido]ceph-3-em-4-carboxylic Acid (syn ~ isomer) ; 10 Preparation of the acid chloride was similar to the method described in Example 9 except that 2-methoxyimino-2-(fur-2-yl) acetic acid (syn isomer) (282mg) was used as the starting material. The acid chloride was isolated as off-white crystals.
A solution of the acid chloride (ca 1.67mmole) in dry acetone (17ml) was added dropwise (at ca 10) to a solution of (6R,7R)-7-amino-3-N-methylcarbamoyloxymethylceph-3-em- -4-carboxylic acid (287mg) and sodium hydrogen carbonate (252mg), in water (20ml) over 15 minutes. The mixture was main-tained at 5 to 10 for lhour by which time reaction was complete by tlc. The mixture was worked up in a similar .

manner to that described in Example 9 to yield the title compound (258mg) as a solid, m.p. (M80) 159 [~]D
+58.9 (c 1.08, DMS0), A (pH6 phosphate buffer) 273nm ( 17,360) with inflections at 260.5 ( 15,300) and 285nm (~ 15,825).

~ ' Preparation (6R.7R)-7-Amino-3~N-methylcarbamoyloxyTnethylceph-3-em-4- ~ , carboxylic Acid.

A suspension of (6R,7R)-7-amino-3-hydroxymethylceph-3-em-4-carboxylic acid (1.029g) in dry dichloromethane (50ml) was treated under nitrogen with triethylamine (0.436g) and with tri-n-butyl tin oxide (1,25g) and the mixture was stirred for 30min. Methylisocyanate (0,570g) in dry dichloromethane (5ml) was added and the reaction stirred at 22 for 4 hr. The insoluble material was filtered off and water (2ml) was added, the solution was cooled and the pH adjusted to 3.1 with formic acid.
The resulting suspension was stirred for 30min at ca.5 and the precipitate filtered off, washed with cold water and dried in vacuo to give the title amino-acid (0.482g) [a]D +34 (c 0.70, DMS0), ~max (pH 6 buffer) 263nm (E 7,100~, ~inf 246nm (6,300).

' ~

Claims (37)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the preparation of an antibiotic com-pound of the general formula (I) (where R represents a furyl, thienyl or phenyl group; Ra re-presents a C1-C4 alkyl group, a C2-C4 alkenyl group, a C3-C7 cycloalkyl group or a phenyl group and Rs represents a C1-C4 alkyl group, a C2-C4 alkenyl group, a C3-C7 cycloalkyl group, a benzyl group or a phenyl group) or a non-toxic derivative thereof, the compound being a syn isomer or existing as a mixture of syn and anti isomers containing at least 90% of the syn isomer, characterized in that one either (A) condenses a compound of general formula (III) (wherein B is >S or S?O; R1 is hydrogen or a carboxyl blocking group; Rs has the meaning defined above; and the dotted line bridging the 2-, 3- and 4- positions of the molecule indicates that the compound may be a ceph-2-em or ceph-3-em com-pound) or an acid addition salt or N-silyl derivative thereof with an acylating agent corresponding to the acid (IV) (wherein R and Ra have the meanings defined above) or with an acylating agent corresponding to an acid of formula R.CO.COOH
(where R is as defined above); or (B) reacts compound of the formula (V) (wherein Acyl is the group or the group R.CO.CO, and B, R1 and the dotted line have the above-defined meanings) with an isocyanate of formula Rs.NCO
(wherein Rs has the above defined meaning); whereafter, if necessary and/or desired in each instance, any of the following reactions (C), in any appropriate sequence, are carried out:-(i) conversion of the precursor group R.CO.CO- into the desired group (ii) conversion of a .DELTA.2 isomer into the desired .DELTA.3 isomer, (iii) removal of any carboxyl blocking, and (iv) reduction of a cephalosporin sulphoxide product to yield the corresponding sulphide; and finally (D) recovering the desired compound of formula I, if necessary after separation of syn and anti isomers and if desired after conversion of the compound to a non-toxic derivative thereof.

2. A process according to claim 1 in which R is fur-2-yl, Ra and Rs are methyl groups.

3. A process for the preparation of (6R,7R)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid (syn isomer) and its sodium salt which comprises reacting (6R,7R)-7-[2-(fur-2-yl)-2-methoxyimino-acetamido]-3-hydroxymethylceph-3-em-4-carboxylic acid (syn isomer) with methyl isocyanate and when the sodium salt is required reacting the acid so obtained with sodium DL-2-ethylhexanoate.

4. A process according to claim 1 in which R is fur-2-yl, Ra is methyl and Rs is ethyl.

5. A process for the preparation of (6R,7R)-3-(N-ethyl-carbamoyloxymethyl)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic acid (syn isomer) which comprises reacting (6R,7R)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]-3-hydroxy-methylceph-3-em-4-carboxylic acid (syn isomer) with ethylisocy-anate.

6. A process according to claim 1 in which R is fur-2-yl, Ra is methyl and Rs is t-butyl.

7. A process for the preparation of (6R,7R)-3-(,N-t-butyl-carbamoyloxymethyl)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic acid (syn isomer) which comprises reacting (6R,7R)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]-3-hydroxymethyl-ceph-3-em-4-carboxylic acid (syn isomer) with t-butyl isocyanate.

8. A process according to claim 1 in which R is fur-2-yl, Ra is methyl and Rs is allyl.

9. A process for the preparation of (6R,7R)-3-(N-allyl-carbamoyloxymethyl)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic acid (syn isomer) which comprises reacting (6R,7R)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]-3-hydroxymethyl-ceph-3-em-4-carboxylic acid (syn isomer) with allyl isocyanate.

10. A process according to claim 1 in which R is fur-2-yl, Ra is methyl and Rs is cyclohexyl.

11. A process for the preparation of (6R,7R)-3-(N-cyclo-hexylcarbamoyloxymethyl)-7-12-(fur-2-yl)-2-methoxyimino-acetamido]ceph-3-em-4-carboxylic acid (syn isomer) which com-prises reacting (6R,7R)-3-hydroxymethyl-7-[2-methoxyimino-2-(fur-2-yl)acetamido]ceph-3-em-4-carboxylic acid (syn isomer) with cyclohexyl isocyanate.

12. A process according to claim 1 in which R is fur-2-yl, Ra is methyl and Rs is n-butyl.

13. A process for the preparation of (6R,7R)-3-(N-n-butyl-carbamoyloxymethyl)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic acid (syn isomer) which comprises reacting (6R,7R)-3-hydroxymethyl-7-[2-methoxyimino-2-(fur-2-yl)acetamido]-ceph-3-em-4-carboxylic acid (syn isomer) with n-butyl isocyanate.

14. A process according to claim 1 in which R is thien-2-yl, and Ra and Rs are methyl groups.

15. A process for the preparation of (6R,7R)-7-[2-methoxy-imino-2-(thien-2-yl)acetamido]-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid (syn isomer) which comprises (6R,7R)-7-amino-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid with 2-methoxyimino-2-(thien-2-yl)acetyl chloride.

16. A process according to claim 1 in which R is phenyl, Ra is ethyl and Rs is methyl.

17. A process for the preparation of (6R,7R)-7-[2-ethoxy-imino-2-phenylacetamido]-3-N-methylcarbamoyloxymethyl-ceph-3-em-4-carboxylic acid (syn isomer) which comprises reacting (6R,7R)-7-amino-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid with 2-ethoxyimino-2-phenylacetyl chloride.

18. A process according to claim 1 in which R and Ra are phenyl groups and Rs is a methyl group.

19. A process for the preparation of (6R,7R)-3-N-methyl-carbamoyloxymethyl-7-[2-phenoxyimino-2-phenylacetamido]ceph-3-em-4-carboxylic acid (syn isomer) which comprises reacting (6R,7R)-7-amino-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid with 2-phenoxyimino-2-phenylacetyl chloride.

20. A process according to claim 1 in which R is fur-2-yl, Ra is cyclopentyl and Rs is methyl.

21. A process for the preparation of (6R,7R)-7-[2-cyclo-pentyloxyimino-2-(fur-2-yl)acetamido]-3-N-methylcarbamoyloxy-methylceph-3-em-4-carboxylic acid (syn isomer) which comprises reacting (6R,7R)-7-amino-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid with 2-cyclopentyloxyimino-2-(fur-2-yl)acetyl chloride.

22. A process according to claim 1 in which R is fur-2-yl, Ra is methyl and Rs is phenyl.

23. A process for the preparation of (6R,7R)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]-3-N-phenylcarbamoyloxymethylceph-3-em-4-carboxylic acid (syn isomer) which comprises reacting (6R,7R)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]-3-hydroxymethyl-ceph-3-em-4-carboxylic acid (syn isomer) with phenyl isocyanate.

24. An antibiotic compound of the general formula I as defined in claim 1 or a non-toxic derivative thereof, whenever prepared by the process of claim 1 or by an obvious chemical equivalent thereof.

25. (6R,7R)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid (syn isomer) or its sodium salt whenever prepared by the process of claim 3 or by an obvious chemical equivalent thereof.

26. (6R,7R)-3-(N-ethyl-carbamoyloxymethyl)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic acid (syn isomer) whenever prepared by the process of claim 5 or by an obvious chemical equivalent thereof.

27. (6R,7R)-3-(,N-t-butyl-carbamoyloxymethyl)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic acid (syn isomer) whenever prepared by the process of claim 7 or by an obvious chemical equivalent thereof.

28. (6R,7R)-3-(N-allylcarbamoyloxymethyl)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic acid (syn isomer) whenever prepared by the process of claim 9 or by an obvious chemical equivalent thereof.

29. (6R,7R)-3-(N-cyclohexylcarbamoyloxymethyl)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic acid (syn isomer) whenever prepared by the process of claim 11 or by an obvious chemical equivalent thereof.

30. (6R,7R)-3-(N-n-butyl-carbamoyloxymethyl)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic acid (syn isomer) whenever prepared by the process of claim 13 or by an obvious chemical equivalent thereof.

31. (6R,7R)-7-[2-methoxyimino-2-(thien-2-yl)acetamido]-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid (syn isomer) whenever prepared by the process of claim 15 or by an obvious chemical equivalent thereof.

32. (6R,7R)-7-[2-ethoxyimino-2-phenylacetamido]-3-N-methyl-carbamoyloxymethyl-ceph-3-em-4-carboxylic acid (syn isomer) when-ever prepared by the process of claim 17 or by an obvious chemical equivalent thereof.

33. (6R,7R)-3-N-methylcarbamoyloxymethyl-7-[2-phenoxyimino-2-phenylacetamido]ceph-3-em-4-carboxylic acid (syn isomer) whenever prepared by the process of claim 19 or by an obvious chemical equivalent thereof.

34. (6R,7R)-7-[2-cyclopentyloxyimino-2-(fur-2-yl)acetamido]-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid (syn isomer) whenever prepared by the process of claim 21 or by an obvious chemical equivalent thereof.

35. (6R,7R)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]-3-N-phenylcarbamoyloxymethylceph-3-em-4-carboxylic acid (syn isomer) whenever prepared by the process of claim 23 or by an obvious chemical equivalent thereof.

36. A process for the preparation of (6R, 7R)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]-3-N-methylcarbamoyloxymethylceph-3-em-4-carboxylic acid (syn isomer) which comprises reacting (6R, 7R)-7-amino-3-N-methylcar-bamoyloxymethylceph-3-em-4-carboxylic acid with 2-methoxyimino-2-(fur-2-yl) acetyl chloride.

37. (6R, 7R)-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]-3-N-methyl-carbamoyloxymethylceph-3-em-4-carboxylic acid (syn isomer) or its sodium salt whenever prepared by the process of claim 36 or by an obvious chemical equivalent thereof.