CA1064039A - .beta.-LACTAMASE INHIBITORS AND PROCESS FOR THEIR PREPARATION - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Isoclavulanic acid and derivatives of it are dis-closed which have .beta.-lactamase inhibitory and antibacterial properties, the preferred compounds being of the formula (I) wherein R is hydrogen or wherein n is 0 or an integer from 1 to 6; R1 is a hydrogen or a phenol or phenoxy group and R2 is a hydrogen or halogen atom or a C1-4 alkyl, C1-4 alkoxy, -CO2R3 group where R3 is a hydro-carbon group of 1-8 carbon atoms or ;
or pharmaceutically acceptable salts thereof of the group of sodium, potassium, calcium, magnesium and aluminum; or pharmaceutically acceptable esters thereof of the formula .

Description

The present invention relates to novel ~-lactam con-tainin(3 compounds, to their preparation and to compositions containing them, the said ~-lactam containing compounds possessing g-lactamase inhibiting activity as well as a degree of anti bacterial activity.

Belgian Patent No. 827926 discloses inter alia clavulanic acid which is the compound o the formula (0):
H C~2H
rt ~ _ N ~ ~ ~ (0) and its salts and esters. Clavulanic acid is a ~-lactamase inhibitor and an antibacterial agent.

We have now discovered a distinct group of compounds which have ~-lactamase inhibitory and antibacterial properties.

Accordingly, the present invention provides compounds of the formula (I):
.,~

~ ~M~ _~ CH2OR
'CO~H
wherein R is a hydrogen atom or an acyl group and salts and esters thereof.

.

.
.. ., . ~,, . . . , :
. ~ , , .

: ' . ' ~ ~ ' :

Suitably R is a hydrogen atom or an acyl group contalnl.rlg up to 16 carbon atQm~.

Pre~erably R is a hydrogen atom.

Suitably when R is an acyl group it is one that occurs in the acylamino side chain of a known antibacterially active penicillin~r cephalosporin, for example R may be anO_-amino-acetyl, ~-aminophenylacetyl, ~-amino~4-hydroxyphenylacetyl, phenylacetyl, phenoxyacetyl, 2-thienylacetyl, 3-thienylacetyl, ~-hydroxyphenylacetyl, ~ carboxyphenylacetyl, ~_-carboxy-3-thienylacetyl, ~-azidophenylacetyl or p-hydroxyphenylacetyl group. When there is an amino group present this may be protected by conventional means, for example by a carhoxybenzyl group.

Most suitably when R is an acyl group it is one of the sub-formula:
- CO - CH - (C~I2)n- R2

2~ Rl wherein n is O or an integer rom 1 to 6; Rl is a hydrogen atom or a phenyl or phenoxy group and R2 is a hydrogen or halogen atom or a Cl_~ alkyl, Cl_4 alkoxy or Co~R3 group where R3 is a hydrocarbon group oF 1 to 8 carbon atoms.

Pr~ferably n is O ox an integer from 1 to 3; Rl is a hydrogen atom or a phenyl or phenoxy group and R2 is a hydrogen atom or :

. .
, .

: :: : . .. - .. .. ; ... . , :~.
., :: - .. : ~ .: .. : . . .
,:
" ~i .: , ,, ~.: .. . . - ' . . - ., ?

Co2R4 group where R4 ls a phenyl or benzyl group.

Suitable salts or esters of those compounds of the invention wherein R is an acyl group are those described hereinafter as suitable for those compounds of the invention wherein R is a hydrogen atom.

A particularly suitable group of compounds of the formula (I) are those of the formula (II):
H

(II~

N ~ ~ H~OH

and pharmaceutically acceptable salts and esters thereof.

Suitable salts include sodium, potassium, calcium, magnesium, aluminium and conventional substitute~ anmlanium salts.

Most suitably the salts of the compounds of the formula (II) are those of the formula (III):

H
1 ---r~~ ~

0~ n ~ CH 2 0~1 ( I I I ) C02~ MJ
wherein ~'is a sodium or potassium ion~
Such salts may form hydrates.

: . ~ . .. : .
'~
: .

- , :: . . .:
, Further particularly suitable groups of compounds of the formula tI) are those oE the ormula (IV)-~ ~ ~
~ ~ (IV) O ~ CH20H

wherein A is a group such that C02A is an ester groupO10 Suitably ~ is an inert organic group of up to 16 carbon atoms and most suitably an inert organic group o up to 12 carbon atoms.

Suitable values for A include alkyl, alkenyl, alkynyl, aryl or aralkyl groups any of which may be substituted if desired.

Suitabie substituents which may be included in the group A
include halogen atoms and lower alkoxy, hydroxy, lower acyloxy or lower aryloxy groups.

When used herein the term 7 lower' means the group contains up to 7 carbon atoms.

Thus for example A may be a methyl, ethyl, n-propyl, iso-propyl, straight or branched hutyl, pentyl, heptyl, octyl, nonyl r decyl, undecyl r dodecyl, vinyl, aillyl, butenyl, cyclopropyl, cyclobutyl, _ r : ~ . ' ' . ~ , , ' , ,- . . '; : ' .- ', : : ' ' :
:' ~ . -: .. ~ : ' : ~ : ' . . . , . ' - .
`' ~, , , :,:

cyclopentyl, cyclohexyl, cycloheptyl, cyclohexenyl, cyclohexadienyl, methylcyclopentyll methyyyclohexyl, ben2yl, benzhydryl, phenylethyl, naphthylmethyl, phenyl, naphthyl, propynyl, tolyl, 2-chloroethyl, 2,2,2,-trichloroethyl, 2,2,2,-trifluoroethyl, aoetylmethyl, ben201methyl, 2-methoxyethyl, 2-dimethylaminoethyl, 2-diethylamino-ethyl, 2-piperidinoethyl, 2-morpholinoethyl, 3~dimethylaminopropyl, p-chlorobenzyl, p-methoxybenzyl, p-nitrobenzyl, p-bromobenzyl, m-chlorobenzyl, 6-methoxynaphthyl-2-methyl, p-chlorophenyl or p-methoxyphenyl group.

A preferred group of compounds of the formula (IV) are those wherein A is a group of the sub-formulae (a) - (d):
CAlA2 X - C0 - A3 ~a) - CH -1 _ ~
0 (b) - CHA4As (c) - A6 .. (d) wherein Al is a hydrog~n atom or a methyl group; A2 is a hydrogen atom or a C1_~ alkyl, phenyl or benzyl group; A3 is a lower alkyl, aryl or C7_11 aralkyl group; X is oxygen or sulphur; Z is a divalent organic group; A4 is a hydrogen atom or an inert aryl group; As is an inert aryl group; A6 is a hydrocarbon group of 1 to 9 carbon atoms optionally substituted by halogen atoms or by lowex alkyl, 2~ lower acyl, lower etherified or acylated hydroxy groups.

.
.

, : . . .
, In the above sub-formulae most su:itably ~l is a hyc:lrocJen atom;

~2 is a hydrogen atom or a methyJ. group; A3 is a methy],-~ -hutyl or phenyl ~roup; X ls oxyc~en; Z is -CH2C~ CH=Cfl--, ,~D "~ ""~
. OC113 A~ is hydrogen, phenyl, tolyl, halophenyl or methoxyphenyl group; A5 i5 a phenyl, tolyl, ha].ophenyl or methoxyphenyl group and ~6 is a hydrocarbon group of l to 6 carbon atoms optionally substituted by Cl, Br/ I, CF3, C(CH3)3, methoxy, acetyl, benzoyl or acetoxy groups.

A further preferred group of compounds of the ormula (IV) are those wherein A is a group of the sub-formulae (e) and ~f):

- C - O - CO - Ag A8 (e) - CH ~ Al2 Alo C = All wherein A7 is a hydrogen atom or a methyl group; A8 is a hydrogPn atom or a methyl, ethyl or phenyl group; Ag is an alkyl group of l to 6 carbon atoms or a phenyl or benzyl group; Alo is -CH2CH2-, -CH=CH-~
~ ' OC
~ J ~ ~ G~

and All and Al2 ara oxygen or sulphur atomsO

~, . . .. . .

, ~ .

In the above sub-ormulae (e) an~. (f) A8 is more suitably a hydrogen atom; Ag is more suitably a methyl, ethyl, propyl, butyl or phenyl group; All and A12 are more suitably oxygen atoms and Alo is more suitably a ~ G~ \

The esters of the compounds o the formula (I) wherein the ester group is convertible to the free carboxylic acid or a salt thereof are valuable intermediates in the preparation of the compounds of the formula (II) or a salt thereof.

One particularly suitable group of intermediates of this kind are those of the formula (V):

F~, (V) , CH2OR

wherein R is as defined in relation to formula (I) and the group Co2R5 is an ester group which is convertible to a carboxylic acid group or a salt thereof by hydrogenolysis~

.:

~ - , . , :
-: : :

, : , , Suitable g~oups R5 include -t}-le ben~yl, naphtllylm~thyl., benzhydryl ox trityl groups ancl their iner-t substi.tuted derivatives such as the 4-bromoben~yl, 3,4-dimcthoxybenæyl, 6-methoxy-2-naphthylmethyl, 4,4-dimethoxyb~nzhydryl, 2--nitro-benzyl or like group.
Of all the foregoing compounds, a pre:Eerred group are those of formula I

~ N 2 (1) o C02~1 wherein R is hydrogen or -Co-fH- (CH2)n-R

Rl wherein n is 0 or an integer from 1 to 6; R is a hydrogen or a phenyl or phenoxy group and R is a hydrogen or halogen atom or a Cl 4 alkyl, C1 4 alkoxy, -CO2R group where R is a hydro-carbon group of 1-8 carbon atoms or 11 -NHC~OCH2C6H5;
or pharmaceutically acceptable salts thereof of the group of sodium, potassium, calcium, magnesium and aluminumi or pharmacetuically acceptable esters thereof of the formula ~ n /~ N ~ \
o ~\ C11201 ~`7 ~ _9_ ' ~ ' ^ ~ " "' '', : ' ~, .

. ~ ` ' ' . ' .
:' ' ~ ` ' ' :
.

wherein A is a hydrocarbon ~Jroup oE 1 to 9 carbon atoms or a hydrocarbon group of 1 to 9 carbon atoms substituted by one or more halogen, lower alkyl, lower acyl, lower e-therified or acylated hydroxy ~roups.
In a composition aspec-t, the present invention provides a pharmaceutical composition which comprises a compound of the ormula (I) as hereinbefore described. Such compositions will also comprise a pharmaceutically acceptable carrier.
The compasitions of this invention will normally be adapted for adminis-tration to humans and other mammals, for example, in conventional modes of treatment of diseases of the urinary tract, respiratory system and soft tissues as well as diseases such as otitis media and mastitis and the like.
Suitable forms of the compositions of this invention include tablets, capsules, creams, syrups, suspensions, solutlons t reconstitutable powders, and sterile forms suitable for injec-tions or infusion may be used. Such compositions may contain conventional pharmaceutically acceptable materials such as diluents, binders, colours, 1avours, preservatives, disin-tegrants and the like in accordance with conventional pharma-ceutical practice.

-9a-~ ` .

` ~ ' ' . ' ' ' ~ , ' '. ' ' , ' , ' ' ' ' ' ~ ' ' . . '" ' ;
.' ~ ' ` ' . ' ~ ' ' , .'` "`
' ' ' ' ' : ' . ' ' , . ' ' ": ' . ~ ' :
. . , ' . : ' . . ~ ~ .

The compo-uld of formula (I) may be presellt in -the composi-tion AS sole therapeutic agen-t or it may be present togJether w:;th other -therapeutic agel1ts such as a penicillin or ceph~llospor.in an-tibio-tlc. Thus, sui-table penicillin or cephalospori.n 5 an-ti.bio-tlcs ~or .inclus.i.on in -the composiLtion of this inverltion include berlzylpen:ici1.1in, phenoxymethylpenicilli.n, carbenic:i].].in, me-thicillin, propicil]in, he-tacillin, ampiclllin~ amoxycillin7 ticarcillin, cephaloridine, cephalothin, cephalexln~
cephamandole~ cephaloglycin, cefuroxime and in-vivo hydrolysable esters of suoh compol~ds such as the phenyl and indanyl esters of carbenicillin and ticarcillin, -the ace-toxymethyl ester of benzylpenicillin and the pivaloyloxymethyl and ph-thalidyl ester of ampicillin and amoxycillin.

When present in a pharmaceutical composi-tion together wi-th a penicillirl or cephalosporin, the ratio of the compGund of formula (I) ~resent to penicillin or cephalospor.in present m.ay be from, for example, 10: 1 to 1.: 3 and advantageously maSr l~e 5: 1 to 1: 2? ~or example5 3: 1 to 1: 1.

The total quantity o. antibacterial agents present in any unit dosage form will normaily be between 5~ and 15nO mg and ~ill u~u:all~- be between 100 and 1000 mg. ~owever, injec~able or infusabi.e composi-tions may con-tain greater quantit.ies if desired, for example; 4 g or more of ac-tive material.

.

. . . ~ .
.

~, ., ~, ' , . ' ~

Norma~l~ly be~ween 50 and 6000 m~ of the compositi.ons o f` the invention w.i~.l be administered each clay o.E treatmerlt b~lt more usually betwee~ 500 ancl 3000 mg of`-the compositions o~
the inven-tion will be administered per da~O However; for the trea-tment o:E severe systemic infections or in~ections o~
part.icularly in-transigent organisms, higher doses may be used in accordance with clinic~l practice.

The present inventi.on also provides a process for the preparation of a compound of the lormula ~I) as hereinbefore dePined or a salt or ester thereof which process comprises the isomerisation of a compound of the formula (VI):

.', ~_~' '. .

(VI) CO ~' ' ' or a salt or ester thereof wherein R is a hydrogen atom or an acyl group.

. Preferably the reaction is carried out on a compound of the fol~ula (~I ? wherein R is a hydrogeIl atom~

From one aspect the isomerisation reaction compri.ses contacting a compound of the formula (VI) with a tran$ition me-tal catal~s-t in the presence of hydrogen.

.
-- 11 -- . - .

.

. :. . - - . , - ~ ~ : .. ~ . . , .. . . . ~ :
., . ~ ,- , .

If the isomerisation reaction is carried out on an ester o:~
a compound of the formula (VI) then if this ester group i.s a group Co2R5 wherein Co2R5 is as defined in relation to :formula (V), the end product is often a compouncl of the formula (I) or a salt thereof.

A part.icularly suitable method of preparing a compound of the ormula (II) or a salt thereof comprises contac~ing a compound of the formula (VII):

O /
t: 02R5 wherein Co2R5 is as defined in relation to formula (V) with a transition metal catalyst in the presence of hydrogen, the said reaction being carrled out in the presence of base when it is desired to prepare a salt of the compound of the formula (II)~

A particularly suitable transition metal catalyst for carrying out the isomerisation reaction is palladiuml for example 10 palladium on charcoal.

When carrying out the isomerisation reaction the ratio of the weight of transition metal catalyst present to the weight of compound of the formula (VI) or tVII) present will suitably be less than 1 : 3, for example 1 : ~5 to 1 : 3. When used herein, the term 'the weight of transition metal catalyst' includes the .

- ` ` ' :

weight of any support provided for the transition metal catalyst.

If the reaction is carried out in the presence oE 1 atmosphere of hydrogen, then the reaction will normally be over in less than 10 hours. Particularly prolonged reaction times should he avoided as they can lead to an unaccep~able degree of reduction of the exocylic double bond of compounds (I) or (II).

The reaction may be carried ou~ at any non-extreme temperature, for example, -20C to +100C, such as -5C to +40C, for example, 0C to +20C.

The;reaction is normally carried out in an organic solvent inert under the reac~ion conditions. Suitable solvents include lower alkanols such as ethanol, low boiling halohydrocarbons such as chloroform and dichloromethane, ethers such as tetrahydrofuran and the like solvents.

It should be realised that the compounds of formulae ~VI) and tVII) are not always entirely converted to the corresponding compounds of the formula (I~ and (II) and that frequently an equilibrium mixture of compounds (VI) and (I) or (VII) and (II) is produced. Such mixtures may then be separated if desired by conventional means, for example, chromatographically.

.
:- ,. ~.......... ... . .. .. . . .

, . : . . , : ., , . : ~, .
. , ~ : . . : :, :

,;. -, ~ ,, . :,: -. . ~:

From a urther aspect the isomerisation reaction comprises the ultra-violet irradiation of a compound of the formula (VI):

N ~

or a salt or ester thereof wherein R is a hydrogen atom or an acyl groupO

This ultra-violet irradiation is most suitably carried out on thP benzyl ester of a compound of the formula (VI), ~or example the benzyl ester of the compound of the formula (VI) wherein R
is hydrogen.

This reaction is normally carried out in a degassed organic solvent such as benzene, carbon tetrachloride, acetonitrile or other conventional solvents.
~

This reaction is normally carried out in an inert atmosphere such as argon or nitrogen.

Thls reaction is normally carried ou~ at ambient temperature Eor the sake of convenience but any non-extreme temperature may be used, for example, -~0 to +80C, although moderate ~emperatures are preferred, for example 0C to +30C.

. .
~:
.
. -..
~ .. ' '. ' ' .. ' ' '' ' '' ~ .' . ' ' ' ' .' ' , :

In accordance with conventional ~-ractice a photosensitizer may be included if desired. Thus such agents as dibenzyl, iodine, acetophenone, benzophenone and the like may be included.

Wide or narrow spectrum u.v. may he employed to produce ~hotolytic isomerisation of the compound of formula (VI). We have found that Hanovia low and medium pressure mercury lamps give satisfactory results. In use such lamps may employ a water-coolinq jacket o silica or glass (Pyrex).

When a compound of the formula (VI) is irradiated with ultra-violet light the compound of the formula (I) may be formed in admixture with the starting material or with a numher of other products. This mixture may be separated by conventional means, for exampIe, by chromatography. We have ~ound that separation of the compounds o~ the formula (I~ may often suitably be effected by column chromatography, for example by column chromatography on silica gel with a ethyl acetate/cyclohexane mixture.

The carboxylic acid derived func~ion at the 2- position oE the compounds of the formula (I) may be converted to another carboxylic acid derived function by conventional methods well known to those skilled in the art.

Thus when there is a free carboxylic acid group at the 2- position this may be converted to an ester group by reaction with an alcohol AOH wherein A is as defined in relation to formula (IV) in . .
~ - 15 -. . -. : , . .
: : : .. ,' : , ,, : ' : ' ~, , ... ,, ~ ' ,, ' .: . . ':
,: . .
:. . .

the presence of a condensation promoring agen-t, such as dicyclohexylcarbodiimide, or by reaction with a diazocompound, such as diaZomethane or alternatively it may be converted into a salt by treatment with base, such as sodium or potassium bicarbonate.

A salt oE a compound of the formula ~I) may be converted into an ester by a conventional nucleophllic substitution reaction by reaction with a compound ~Q wherein A is as deined in - relation to formula (IV) and Q is a good leaving group such as r~ I~ OSO2C~13, 0~02C~H4CH3 or the like.

The compounds of the formula ~I) wherein R is an acyl group may be prepared from the corresponding compound of the formula (I) wherein R is a hydrogen atom by conventional acylation procedures, for example by reaction with a compound of the formula ROH wherein R is an acyl group. Suitably this reaction is carried out in the presence of a condensation promoting agent, such as dicyclohexylcarbodiimide. Suitable acylation procedures are described in our co-pending Canadian application S.N. 237,296 filed 8 October 1975.

The following Examples illustrate the invention:

: ' ~ C~i~0H
L ~ h~ + (I) ~2C1~2CC6~15 C02CH2COC6H5 (1) (2) A dilute solution of phenacyl clavulanate (1) in dry ~enzene was irradiated in a quartz vessel using a 450 watt Hanovia medium pressure mercury lamp (ohtained from Engelharfl l~anovia Lamps, Bath Road, Slough, Buckinghamshiret England3 under nitrogen for 3 hours. The solvent was removed and t,l~c. of the residue showed two components which were separated by chromatography on silica gel~ The more polar component was examined spectroscopically and found to be identical with the starting material, The less polar component was examined by h~p~loc~ and found to be a mixture of two compounds which were separated by preparative h~p~l~co The second eluted component was obtained as a colourless oil and was assigned the structure -(2) on spectroscopic evidence.
IOr. (film): 3~80, 1790, 1750, 1690 cm 1, NOm.r. (CDC13): 3.02 (lH, dd, J 17Hz, J' lHz, 6~ -H); 3052 (lH, dd, J 17Hz, J' 3Hz, 6~ -H); 4,27 (2H, d, J 9Hz, ~2OH);
5.43 (lH, s, CHCO2R); 5.48 (lH, mr CHCH2OH) 5.52 (2H, s, CH2COPhj; 5,73 (lH, dd, J 3Hz, J' lHz~ 5-H) and 7.7 (5H, m, aromatic -H), , .;

: . .
-, . ~ - :. , : ' -~XAr~lpI~F, ~
~ s .

~ CH?OH ~

O O/J `~/ ~ H Oli CO~C~2C6~s ~02C ~I~C6~-15

(3) (l~) A solution of benzyl clavulanate ~3) in dry benzene was irradiated under nitrogen in a ~uartz vessel using a Hanovia Photochemcial 'Reading Reactor' to give benzyl isoclavulanate

(4) as a colourless oil, yield 40% after column chromatography.
The lamp unik (obtained from Engelhard Hanovia Lamps, Bath Road, Slough, Buckinghamshire, England) con~ains two low pressure ultra-violet lamps of 45 watts each with an energy max at 254 n.m.
I.r. (CH2C12): 3550, 1795, 1740, 1685 cm 1 N.m.r. (CDC13): 1.85 (lH, s, CH2OH); 2.98 (lH, dd, J 17Hz, J' lHz, 6~ -H); 3.45 (lH, dd, J 17Hz, Jl 2 5Hz, 6~J-H); 4 05 (2H, d, J 7Hz~ CH2OH); 5 18 ~2H, s, CH~C6H5) 5.32 (lH, s, CHCO2CH2C6Hs);

5.35 (lH, m, obscured by signal at 5.32, CHCH2OH); 5.63 (lH, dd, 3 ; 2 5Hz, J' lHz, 5-H); 7 3~ (5M, s, aromatic -H). The mass spectrum of the pxoduct showed a molecular ion at m/e 289.0949 (C15H15NO5 requires 289 09503O

':

~, . , , , - . -- .
' EX~IPLE ~

o/~ 0~l ~C1~20~
~02CH2C6H5 lc~2c~l2(~6~ Br C02CH2C6~14Br (3) (5) (6) Benzyl clavulanate (3) (94 mgs) in ethanol (8 mls) was hydrogenated over 10~ Pd/C (30 mgs) and soclium hydrogen carbonate (28 mgs) for 60 minutes~ The catalyst was Eiltered, washed with water and then ethanol and the combined filtrates were evaporated. The residue was dissolved in dry dimethyl~
formamide (2.5 ml) containing p-bromobenzyl bromide (245 mgs) and the solution was left at ambient temperature for 2 hours~ The solution was fractionated on silica gel eluting first with ethyl acetate-hexane (1:1) and Einally ethyl acetate.
Fractions 1~ were evaporated to give p~bromobenzyli~o-clavulanate (5) (11 mgs) as thin rods, m.p. 134 - 134.5C
~from methylene chlori~e - carbon tetrachloride). Fractions 21 - 24 were evaporated to give p-bromobenzylclavulanate (6) (52 mgs) as needles, m.p. 103 - 104 C ~from methylene chloride - carbon tetrachloride).
.
The structures and absolute stereochemistry of the two products (5) and (6) were confirmed by X-ray analysis~

. . :~. : . . :
.
. .
.
.: - -: . , -- ~ . ~ . .
: . : ., : :
', , ' .. , ' ,: ' :

E~lp~ o?
.

~ E-I
o~N o>~ ) o-~>q\

C2CH2C6~l5 ('2 Na A mixture of benzyl isoclavulanate (4) (60 m~s), sodium hydrogen carbonate (17.6 mg) and 10~ palladium on charcoal (20 mg) in ethanol was hydrogenated at 20C and 1 atmosphere pressure for 105 minutes after which time t.l~c. (ethyl acetate - cyclohexane; 1:1) showed the reaction to be complete, The catalyst was filtered off and washed with water and the filtrate and combined washings evaporated. The residue was twice treated with ethanol and evaporatedl and acetone and I evaporated, and triturated with acetone/ether to give sodium isoclavulanate (7) (30 mg) as an off-white powder.
N~mOr. (D20): 3.10 (lH, d, J 17.5Hz, 6 f?-CH); 3.64 (lH, dd, J 17.5Hz, J' 3.aHz); 4.1R (2H, d, J 7.5Hz, CH~OH); 5.22 (2H, m, =C~-CH20H, 3-CH); 5.86 (lH, d, J 3.OHz, 5-CH), The minimum inhibitory concentrations (MIC~ in ~g/ml o~ sodium isoclavulanate, ampicillin and combina~ions of sodium isoclavulanate with ampicillin against certain ~~lactamase pro-ducing organisms are given below in Table 1. The results were obtained by the microti~re technique with an inoculum of 1/500 of overnight broth.

~` , :~

~ In O
U~ ~ O
a r ~ l _ U
~1 O r~ r-l :~ a~
_~t~ r~ (~
.~ O rl ~C h V t~ ~1 o -r ~ ~ O U~

~:~1 ~ H
r-l ~ -- --r Q t rl 1 ~1a~ 1 r~ ) ~
rl~1 Ql rl O ~1 CO
O ~:; . O ~ ~ iJ') ~i ~ t,) r r~ O
~1 ~ l~ ,~
r-l ~ ~J tll H
~ ~ U~ _ _. ___, 1~ ~r S
(~ ~ rl ~1 o l I I _I P _l ~ o . . _.
o O ~. .~

'i o o ..

rl ~ __ . .~ U~l ~1 ~ ~ ~ ~ . [~
o~ I X ~ R o ~ u~ ~1 K ~ _ ' , ,, . ,. , - . , , ... , , .. .. . . . . .. , . .. : . .

EXAMPLP, 5 ~1 H

/~rN ~ ~ N
' CH2 OH I CH~ OH
t:~O~,~ Na~ C02CH2C6~i5Br (7) (5) Sodium isoclavulanate (7) (1~.5 mg3 was treated wi.th p-bromo-benzyl bromide (22.5 ~g) in dry dime-l;'ny1~ormamide for 3 hours a~ter which -time t~l~co (butanol ethanol-water; 16:4:7) showed -the reaction t.o be almost comp`ete. The solvent was : removed in ~acuo and -the residue chroma-tographed on sili.ca gel (elu-tion with ethyl ace-ta-te cyclohexane, 1:1) to give th~ product (5~ (lL~.5 mg) ~.p. 32 - 1~4C, ~' .

1. -- 22 -,i , .

~ 5 ;~
.

.. . .. , .. . . . . . , : --,.. ,: . . ~ . . . :
: . . . . .
.~ . ., ., -,.. : . ~ :.: , ......... . .

EX~MPI,~ 6 .~t~ ~'t3 I,I ,T~
~--~ C6~l5l~C~2~ r-~~~ o ~N ~/C~ ~ C02C~C~ 5 )r- ,/ C~I20C~'~C~E~5 CtO2C~ C6~l5 . C02(YH2C6~T5 ~ ~ ~C~ 5 (L, ~ (fl) Benzyl isocl~1vuIanate (L, ) (82 m~) was dissol~ed in clry m~thylene chloride and benzyl phe2lylmalonic acid (76 mg) added. The solut.ion was cooled to 0C and divyclohex~l-carbodiimide.~57.7 mg) added. The mix-ture was stirred at 0C
~or 1 hour and at room temperature overnight; the mi~ture.w~s filt,ered and the filtrate concentr~-,;ed to give the crude ¦ p~d.uct (8), The crude product was purified by fractionatio~
on silica gel and gradient.elution wi-th ethyl ~;cetat,e/
c~Jc'~hexane gave the product ~8) ~42 mg; 32% yield~ as a I colourless gum.
J..~. (fil.m~: 18Vn59 1745, 1695 cm~l;
N.m.r. ~CDC13): 2.95 (lH, cld~ J 1'7Hz~ J' lHz7 6,B-H);
' 3.42 (1H9 ddS J 17Hz, J' 3~I7, 6~H); ~.57 (2H, m, C=CHCH2~;
L,,59 (lH, s, OCO~HPh); 5.0~ (2~I, s, CHPhCO2CH2Ph); 5.12 (lH, m9 o~vscured9 C-CHCH2); 5.14 (2H7 s9 NCHCO2CH~Ph); 5.35 (lH, bs~ NCHCO2C~2C6H5~; 5.6~ (lH, cld, J 3Hz, J~ z1 5-H) and 7~8~ (1,5H~ S9 ~romatic ~H3; ~n.w~ (mass speotrom~try) 541~

: . ' - . , ' .

:

. -. ~ .. . . ~ . - . , ... , . , . . , . . . . . . -EX~IPLE 7 __ _ H
C6H5CH20coN~c~2co2H
0// -N , ~H2H H

02CH?C6T-15 ) ~
O , CH20CCH2 NHCOCI12C6~5 (~) C02CH2C6H5 Benzyl isoclavulanate (4) (120 mg) was treated with henzyl-oxycarbonyl glycine (84 mg~, pyridine (32 mg) and dicyclo-hexylcarbodiimide (82 mg) in methylene chloride at 0C. The solution was stirred overnight at room temperature and filtered, Silica gel chromatography yielded th~ desired pro-duct (9) as a colourless gum in 72~ yield, I.r, (film): 3370, 1810, 1700-1760, 1665 cm 1;
n.m,r. (CDC13): 3002 (lH, dd, J 17,5Hz, J' lHz, 6 ~-H);
; 3.49 (lH, dd, J 17.5Hz, J' 3Hz, 6~ -H); 309 (2H, d, J 6Hz, CH2NH); 4.67 (2H, m, C-CH,CH2) 5,14 (2H, s, NCHC02CH2Ph);
5-21 ~2H~ s, NH ~ CH2C6H5); 5.46 (lH, bs, NCH~C02CH2C6Hs);
5.72 (lH, dd, J 3Hz, J' lHz, 5-H); 7,38 (lOH, s, aromatic -H)o .

, . .

.

~' .
.~, .. -. ~
- ~ .: .- : . : - .

Claims

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 a compound of formula (I) wherein R is hydrogen or wherein n is 0 or an integer from 1 to 6; R1 is a hydrogen or a phenyl or phenoxy group and R2 is a hydrogen or halogen atom or a C1-4 alkyl, C1-4 alkoxy, -CO2R3 group where R3 is a hydro-carbon group of 1-8 carbon atoms or ;
or pharmaceutlcally acceptable salts thereof of the group of sodium, potassium, calcium, magnesium and aluminum; or pharma-ceutically acceptable esters thereof of the formula wherein A is a hydrocarbon group of 1 to 9 carbon atoms or a hydrocarbon group of 1 to 9 carbon atoms substituted by one or more halogen, lower alkyl, lower acyl, lower etherified or acylated hydroxy groups; which comprises isomerization of a compound of the formula (VI) wherein R is as defined or a salt or ester thereof as defined, said isomerization being carried out by (i) contacting the compound of formula (VI) or salt or ester thereof with a transition metal catalyst in the presence of hydrogen, or (ii) ultra-violet radiation of the compound of formula (VI) or salt or ester thereof, and recovering the compound of formula I or said salt or ester thereof and where required converting the carboxylic acid derived function at the 2-position to another carboxylic acid derived function and/or converting one R group to another R
group.

2, A process for the preparation of a compound of formula I wherein R is , or a salt or ester thereof as defined in claim 1 which comprises preparing the compound of formula I
wherein R is H or a salt or ester thereof by the process of claim 1 and further reacting said compound or salt or ester with a compound of formula ROH wherein R is as defined and recovering the required compound and where required converting it to a salt or ester as defined.
3. A process for the preparation of an ester of a compound of formula I as defined in claim 1 which comprises preparing a salt of a compound of formula I by the process of claim 1 and further reacting it with a compound AQ wherein A is as defined in claim 1 and Q is C1, Br, I, OSO2CH3 or OSO2C5H4CH3 and recovering said ester.

4. A process for the preparation of an ester of a compound of formula I as defined in claim 1 which comprises preparing a compound of formula I by the process of claim 1 and further reacting it with a compound AOH while A is as defined in claim 1 and recovering said ester.
5. A process according to claim 1 wherein R is a hydrogen atom.
6. A process according to claim 1 wherein the isomerisation reaction comprises contacting a compound of the formula (VI) or a salt or ester thereof as defined with a transition metal catalyst in the presence of hydrogen.

7. A process for the preparation of the compound of formula I wherein R is H or a salt thereof as defined in claim 1 which comprises contacting a compound of the formula (VII) (VII) wherein R5 is benzyl, 4-bromobenzyl, or 3,4-dimethoxybenzyl, with a transition metal catalyst in the presence of hydrogen, the reaction being carried out in the presence of a base when it is required to prepare a salt of the compound of formula I as defined in claim 1 and recovering said compound or said salt.
8. A process according to claim 7 wherein the hydrogen is at a pressure of 1 atmosphere.

9. The process of claim 7 wherein the transition metal catalyst is palladium.
10. A process according to claim 7 wherein the reaction is carried out in a solvent inert under the reaction conditions.
11. A process according to claim 10 wherein the solvent is methanol, ethanol, dichloromethane or tetrahydrofuran.

12. A process according to claim 1 wherein the isomerisa-tion process comprises the ultra-violet irradiation of a compound of the formula (VI) or a salt or ester thereof as defined in claim 1.
13. A process according to claim 12 for the preparation of a benzyl ester of a compound of the formula (1).
14. A process according to claim 12 wherein the reaction is carried out in an organic solvent.
15. A process according to claim 14 wherein the organic solvent is benzene, carbon tetrachloride or acetonitrile.
16. A process according to claim 12 wherein the isomerisation reaction is carried out in the presence of a photosensitizer.
17. A process according to claim 12 wherein the ultra-violet radiation is emitted by a medium pressure mercury lamp.
18. A process according to claim 2 wherein the acylation reaction is carried out in the presence of a condensation promoting agent.
19. A process according to claim 4 wherein the further step is carried out in the presence of a condensation promoting agent.
20. A process for the preparation of phenacyl isoclavulanate which comprises the isomerization of phenacyl clavulanate in an inert organic solvent by ultraviolet radiation and recovery of phenacyl iso-clavulanate.
21. A process for the preparation of benzyl isoclavulanate which comprises isomerization of benzyl clavulanate in an inert organic solvent by ultraviolet irradiation and recovery of the benzyl isoclavulanate.
22. A process for the preparation of b-bromobenzyl isoclavulanate which comprises isomerization of benzyl clavulanate in an inert organic solvent in the presence of hydrogen and palladium on carbon catalyst, followed by reaction with p-bromobenzyl bromide in an inert organic solvent and recovery of p-bromobenzyl isoclavulanate.

23. A process for the preparation of sodium isoclavulanate which comprises the preparation of benzyl isoclavulanate by the process of claim 21 plus the additional step of deesterifying the product benzyl isoclavulanate with hydrogen using pallodium on carbon catalyst in the presence of sodium bicarbonate in an inert organic solvent and recovering said sodium isoclavulanate.
24. A process for the preparation of p-bromobenzyl isoclavulanate which comprises preparing sodium isoclavulanate by the process of claim 23 and further reacting it with p-bromobenzyl bromide in an inert organic solvent and recovering said p-bromobenzyl isoclavulanate.
25. A process for the preparation of the compound which comprises preparing benzyl isoclavulanate by the process of claim 21 and further reacting it with benzyl phenyl malonic acid in an inert organic solvent and recovering said compound.

26. A process for the preparation of the compound which comprises preparing benzyl isoclavulanate by the process of claim 21 and further reacting it with benzyloxycarbonyl glycine in an inert organic solvent in the presence of dicyclohexyl carbodicimide and recovering said compound.
27. A compound of the formula (I) wherein R is hydrogen or wherein n is 0 or an integer from 1 to 6; R1 is a hydrogen or a phenyl or phenoxy group and R2 is a hydrogen or halogen atom or a C1-4 alkyl, C1-4 alkoxy or CO2R3 group where R3 is a hydrocarbon group of 1-8 carbon atoms ; or a pharmaceutically acceptable salt thereof of the group of sodium, potassium, calcium, magnesium and aluminum or esters thereof of the formula wherein A is a hydrocarbon group of 1 to 9 carbon atoms or a hydrocarbon group of 1 to 9 carbon atoms substituted by one or more halogen, lower alkyl, lower acyl, lower etherified or acylated hydroxy groups when prepared by the process of claim 1 or an obvious chemical equivalent.
28. Phenacyl isoclavulanate when prepared by the process of claim 20 or an obvious chemical equivalent.
19. Benzyl isoclavulanate when prepared by the process of claim 21 or an obvious chemical equivalent.
30. p-bromobenzyl isoclavulanate when prepared by the process of claim 22 or an obvious chemical equivalent.

31. Sodium isoclavulanate when prepared by the process of claim 23 or an obvious chemical equivalent.
32. p-bromobenzyl isoclavulanate when prepared by the process of claim 24 or an obvious chemical equivalent.
33.

when prepared by the process of claim 25 or an obvious chemical equivalent.
34.

when prepared by the process of claim 26 or an obvious chemical equivalent.