CA1332059C - Process for preparing cis-1-carba(1-dethia)cephalosporins and intermediates therefor - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The present invention provides 1-benzyl (or substituted benzyl)-3.beta.-[4(S)-aryl-oxazolidin-2-one-3-yl]-4.beta.-(2-arylvinyl)azetidin-2-ones represented by the formula (1):

1 wherein Ar is phenyl, C1-C4 alkylphenyl, halophenyl, C1-C4 alkoxyphenyl, naphthyl, thienyl, furyl, benzothienyl, or benzofuryl; R is phenyl, C1-C4 alkylphenyl, C1-C4 alkoxyphenyl, or halophenyl; Y is -CH=CH-, or -CH2-CH2-;
and R' is phenyl,C1-C4 alkoxyphenyl halophenyl, furyl or naphthyl. These compounds of Formula (1) are provided via cycloaddition of a 4(S)-aryloxazolidin-2-one-3-ylacetyl halide and an imine formed with a benzylamine and a 3-arylacrolein, eg. cinnamaldehyde. The above azetidinones are useful chiral intermediates in an asymmetric synthesis of 1-carbat(-dethia)-3-cephem-4-carboxylic acids and esters (which have utility as antibiotics), and are also useful as intermediates in the synthesis of monocyclic .beta.-lactam antibiotics.

Description

13320~9 PROCESS FOR PREPARING CIS-l-CARBA(l-DETHIA)CEPHALOSPORINS
AND INTERMEDIATES THEREFOR

This invention relates to a process for the preparation of 1-carba(l-dethia)-3-cephem-4-carboxylic acids and derivatives thereof, and to certain novel intermediates of value in that process. In particular, it relates to a chiral process for the preparation of 1-carb~ dethia)-3-cephem-4-carboxylic acids and to l-substituted-3~-(4(S)-aryloxazolidin-2-one-3-yl)-4~-styryl (or substituted styryl)azetidin-2-one intermedi-ates useful therein. Related 4~substituted 3~-(4(S)-aryloxazolidin-2-one-3-yl)azetidin-2-one compounds, -~
useful in the chiral synthesis of other ~-lactam antibiotics, are pro~ided.
The l-carba(1-dethia)-3-cephem-4-carboxylic acids, hereinafter l-carbacephalosporins, possess the 4,6-bicyclic ring system represented by the following structural formula:

o~ ~ 4~
~OOH ~;
. :

wherein the arbitrary numbering system employed accord-, ing to the cepham nomenclature system is used for con-venience as indicated.
The preparation of l-carba-3-cephem-4-carboxylic acids having antibiotic acti~ity is taught in EP14476. -;~

'' "'' ~' ~. ' ~332~

The l-carbacephalosporins thus far have not been ob-tained from natural sources, for example, as microbial metabolites. Accordingly, methods for the total syn-thesis of these promising compounds are highly desirable, particularly methods which are adaptable to large scale manufacture.
l-Substituted-3~-[4(S~-aryloxazolidin-2-one-3-yl]-4~-(2-arylvinyl)azetidin-2-ones are prepared via cycloaddition of a 4(S)-aryloxazolidin-2-one-3-ylacetyl halide with an imine formed with a benzylamine and a 3-arylacrolein, eq. cinnamaldehyde. A preferred inter-mediate, l-benzyl-3~-~4(S)-phenyloxazolidin-2-one-3-yl)-4~-(3-methoxystyryl)azetidin-2-one, is converted asym-metrically to l-carbacephalosporins as follows. The 15 4~-(3-methoxystyryl)substituted azetidinone is first ~-hydrogenated to the corresponding 4~-[2-(3-methoxy-phenyl)ethyl]azetidinone and lithium-ammonia reduction of the latter in the presence of t-butyl alcohol pro-vides 3~-amino-4~-[2-(5-methoxycyclohex-1,4-dienyl)-ethyl]azetidinone. Following protection of the 3-amino group of the reduction product the diene is oxidized with ozone to form the ~-keto ester, me~hyl 5-[3 (protected amino)azetidin-2-one-4-yl]-3-oxopentanoate.
The ~-keto ester is converted to the 4-diazo-3-oxo-25 pentanoic acid methyl ester via diazo transfer and the -~
latter is cyclized with Rhodium (II) to the 7~-protected amino-3-hydroxy-1-carbacephalosporin-4-carboxylic acid methyl ester. Alternatively, the diazo ~-keto methyl ester is converted to an ester more readily removed, eg.
the diazo ~-keto benzyl ester, via transesterification . :: ~;. - : .:
,. ,: : . .:
. . . .
:,; ., .".

: ,:: ~;~, . :,.
.., ..:: .. "~
, . ~ ..

: :',~.'~ :;'''':;

:' --- 1332Q~
X-6605 _3_ with titanium tetraisopropoxide and benzyl alcohol.
The 7-protected amino 3-hydroxy l-carbacephalosporin can be deprotected, acylated with the desired carboxylic acid, reacted with diazomethane and then deesterified to S provide the desired 7~-acylamino-3-methoxy-1-carbacepha-losporin-4-carboxylic acid antibiotic.
Other l-substituted 3~-(4(S)-aryloxazolidin-2-one-3-yl)-4~-substituted azetidin-2-ones are useful ~-~
intermediates to monocyclic ~lactam antibiotics such as the monobactam acids.
In one aspect of the invention there are pro-vided 3~-(4(S) aryloxazolidin-2-one-3-yl)azetidin-2-one intermediates represented by the formula 1 Ar 7 ~ ~ CH

wherein Ar is phenyl, C1-C4 alkylphenyl, halophenyl~
C1-C4 alkoxyphenyl, naphthyl, thienyl, furyl, benzo-thienyl, or benzofuryl; R is phenyl, Cl-C4 alkylphenyl, C1,C4 alkoxyphenyl, or halophenyl; Y is -CH=CH-, or ;~
-CH2-CH~-; and R' is phenyl, Cl-C4 alkylphenyl, Cl-C
alkoxyphenyl, halophenyl, furyl or naphthyl.
Preferred azetidinones are represented by the formula 1 wherein Ar and R are phenyl or substituted phenyl, and R' is phenyl, substituted phenyl, or furyl.
Examples of such preferred compounds are l-benzyl-3~
,,, ~ .

' . ' ~332~9 X-6605 _4_ [4(S)-phenyloxazolidin-2-one-3-yl]~4~-styrylazetidin-2-one, 1-benzyl-3~-[4(S)-phenyloxazolidin-2-one-3-yl]-4~-(3-methoxystyryl)azetidin-2-one, and 1-benzyl-3~-[4(S)-phenyloxazolidin-2-one-3-yl]-4~-[2-(2-furyl)ethenyl]-azetidin-2-one.
The azetidinones represented by the formula 1 are obtained by the cycloaddition of a 4(S)-aryloxazol-idin-2-one-3-ylacetyl halide and an imine formed with a benzylamine and a 3-arylacrolein. The acid halide is converted ln situ with a trialkylamine to the corre-sponding homochiral ketene. The ketene and imine upon cycloaddition provide the azetidinone. Alternatively, the ketene can be generated with the anhydride of the -~
oxazolidinone acetic acid and trifluoroacetic acid, or lS with phosphoryl chloride or phosphoryl bromide. The cycloaddition reaction is a key step in the asymmetric process of this invention for the preparation of l-carba~
(1-dethia)cephalosporins as described ~ereinafter.
The 4(S)-aryloxazolidin-2-one-3-ylacetyl halide employed in the cyclization is obtained with an L-arylglycine represented by the formula la ;
H N~
- Ar I la COOH
wherein Ar has the same meanings as defined for 30 Iformula 1. The preparation is illustrated in the !
following reaction scheme.
; . - . . .;.,;

"-,.' ~ ' ' .~`' ':

:.:

3320~

O O
ll OH- ll la + alk-O-C-Cl alk-O-C-NH~CH-Ar 2a >
COOH ~ -2a + BH3 (CH~)2S redn. alk-O-C-NH ~CH-Ar 3a ", 15 3a + butyllithium cyclize ~ ~H 4a H

Ar P . , 4a + X-cH2-cooalk 1) alkylate ~\ 5a 2) deesterify ) halogenate ~11 IH
Ar In the above scheme "alk" refers to Cl-C4 ;~
alkyl, e q., methyl, ethyl, n-propyl, and ~-butyl; X
refers to halogen, preferably chloro or bromo; X' is chloro, bromo, trifluoroacetoxy, or -OP(-~)X2 wherein X
is halogen; and Ar has the same meanings as previously defined.
In carrying out the preparation of the 4-aryl-oxazolidinone 4a the L-arylglycine is first converted to the carbamate 2a. The arylg ycine is dissolved in agueous base by utilizing only the amount of base needed to form the soluble salt plus a small excess. The solu-tion is cooled to a temperature between about 0C and about 10C and non-stoichiometric amounts of the halo-1 3 3 2 0 5 9 !

:
formate are added in several portions with stirring.
Additional base is added to redissolve the arylglycine and additional haloformate is added portionwise with stirring. This process is repeated in the cold until an excess of the stoichiometric amount of haloformate has been added and carbamate formation is completed. The reaction is preferably carried out as rapidly as possi- ~-ble. Bases such as the alkali metal hydroxides, e.q., sodium hydroxide and potassium hydroxide are preferred. ;;~
Preferably 3N sodium hydroxide is used. The L-carbamate derivative 2a is recovered from the reaction mixture by acidification and extraction of the precipitated car- ;
bamate with a water immiscible solvent eg. a halogenated hydrocarbon solvent such as dichloromethane.
The L-carbamate 2a is reduced with excess borane-dimethylsulfide in tetrahydrofuran at a tempera-ture between about 20C and about 40C to provide the L-alcohol 3a. The borane-dimethylsulfide reagent is added to a solution of the carbamate acid in tetrahydro-20 furan coole~ to about 0C and the mixture is stirred at ~;
the temperature range, conveniently at room temperature, for about 10 hours to 20 hours. The excess borane is ~;destroyed by ~uenching the mixture with water and 3a is ~
recovered by concentrating the mixture by evaporation, ~ ~ -25 diluting the concentrate with more water if necessary, ~ -and extracting 3a with a water immiscible solvent such `~
as methylene chloride. The recovered 3a is of suffi~
cient purity to use directly in the cyclization to 4a, ~`
however, it may be further purified prior to use by ;~
30 recrystaIlization. ~ -. . . .

.:

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

\
1 3 3 2 o ~ 9!
X-6605 _7_ The L-alcohol 3a is then cyclized to the (S)-4-aryloxazolidin-2-one (4a) in an inert solvent with n-butyllithium or an alkali metal alkoxide such as lithium or sodium ethoxide. n-Butyllithium is the preferred base and is generally used in less than the stoichiometric amount. The reaction is carried out for from 2 to 8 hours at a temperature between about 25C
and about 65C and preferably at about 55C. Suitable inert solvents are tetrahydrofuran, 1,2-dimethoxyethane 10 and like ethers. After completion of the cyclization, ~-the reaction mixture is treated with acetic acid in an amount corresponding to the amount of base used, and is concentrated. The oxazolidin-2-one(4a) is recovered from the concentrate by extraction with a suitable organic solvent such as methylene chloride, chloroform, or trichloroethane.
The (S3-4-aryloxazolidin-2-one (4a) is -;~
N-alkylated with a haloacetic acid ester, the ester -deesterified, and the acid converted to the acyl halide ~;~
20 5a. ;
The alkylation of 4a with the haloacetic acid ester is carried out in dimethylformamide or tetrahydro-furan with sodium hydride to provide the (S)-4-aryloxa~
zolidin-2-one-3-ylacetic acid ester. The haloacetic acid ester is represented by the formula X-CH2COOalk in the foregoing reaction scheme, wherein X is chloro or ` ~-bromo and alk is Cl-C4 alkyl. Preferably, alk is i t-butyl or ethyl. Examples of haloacetic acid esters are t-butyl bromoacetate, ethyl bromoacetate, methyl chloroacetate, t-butyl chloroacetate, methyl bromoacetate, .' ~ ~.":

133~

X-6605 -8- ~
: , ~
isopropyl bromoacetate, and like esters. Preferred halo esters are t-butyl bromoacetate and ethyl bromoacetate.
The deesterification of the oxazolidinone acetic acid ester is achieved by standard deesterifica~
tion procedures. For example, the t-butyl ester group is removed upon treatment of the ester with trifluoro- -acetic acid while other lower alXyl esters such as the ethyl ester can be saponified.
The oxazolidinone acetic acid is converted to 10 the acid halide (5a, X' = halogen), preferably the acid ~
chloride, the anhydride formed with trifluoroacetic acid ~ ;
(X'=~COCF3), or with a phosphoryl halide (X'= -O-P(=O)X2).
The acid halide, preferably the chloride, is a preferred source of the ketene for use in the subsequent cyclo-lS addition reaction. The acid chloride is obtained for example with oxalyl chloride in an inert solvent such as benzene, toluene, or xylene. Other con~entional acid `
halide forming reagents may be used.
The (S)-4-aryloxazolidin-2-one-3-ylacetyl -~
halide or anhydride is the functionalized form of the chiral auxiliary moiety used to form the ~-lactam ring of the azetidinone intermediates represented by the formula 1.
The acetyl halide (5a) is allowed to react with the imine formed with a benzylamine and a 3-arylacrolein to form the 1-benzyl-3~-[(S)-4-aryloxazolidin-2-one-3-yl]-4~-(2-arylvinyl)azetidinone (formula 1, Y = -CH=CH).
A minor amount of isomeric cycloaddition product is also formed. The cycloaddition reaction is illustrated in ;
the following reaction scheme , :,;

, ~ ,, ,, '. ,~ ' :~"

~ - 13320~9 sa + R~_~ ~a 7 /
Ar l/
H H

~ 0~ CH

wherein R, R' and Ar have the siame meanings as defined ~-~
for formula 1.
The reaction can be carried out at a tempera- ``~
ture between about -78C and about 25C in an inert organic solvent, ~uch as methylene chloride, chloroform, ~ :~
toluene, or a di- or trichloroethane in the presence of a tri-(Cl-C4 alkyl)amine. The reaction can be accom~
plished by adding a solution of the imine (6a) to a solution of Sa in an inert solvent containing the tri-(Cl-C4 alkyl)amine in an amount in excess of the stoichiometric amount. The tri-(Cl-C4 alkyl)amine should be added to the solution of 5a prior to addition of the imine 6a. The acid derivative Sa and the amine are preferably mixed at a temperature between about -80C and about -50C to form in situ the ketene. The imine 6a should then be added to form the azetidinone 1. ;~
Conveniently, the solvent for the imine is the solvent ln which it was prepared as described hereinbelow. Such ~ : ' !: 1 13320~9 solvents as benzene, toluene, and the xylenes are suit-able. Following the addition of the imine, the reaction is prefera~ly warmed and maintained at about 0C for from 2 to 4 hours. The mixture of the major isomer S ~formula 1) and the minor isomer can then be recovered ~-from the reaction mixture as follows. The reaction mixture is diluted with a water immiscible organic solvent such as methylene chloride or chloroform and is first washed with a weak acid such as tartaric acid or citric acid followed by a wash with sa~urated aqueous alkali metal bicarbonate. After drying, the washed mixture is evaporated to dryness. Most often, the major isomer 1 can be crystallized from the residue from ethyl acetate-hexanes (ca 30% hexanes by volume).
Alternatively, the major isomer can be separated from the minor isomer by chromatography over silica by using step-wise elution or gradient elution. Step-wise elution with ethyl acetate-methylene chloride with a percentage ethyl acetate by volume of from ca 20% will ;~
generally elute 1 while increased polarity (ca 40%-50% ;
ethyl acetate by volume) will elute the minor component. ~ ;
After chromatography isomer 1 can be recrystallized to ~
enhance its purity. ; , ;
The imine 6a employed in the cycloaddition is obtained by condensing a 3-arylacrolein with benzyl-amine or a substituted benzylamine in a suitable solvent. `~
The water produced during the reaction is removed either by using a drying agent or by azeo~ropic distillation.
A small excess over the stoichicmetric amount of the `--acrolein is preferably used. Drying agents such as magnesium sulfate or molecular sieves are suitable.
Organic solvents such as diethyl ether or an aromatic hydrocarbon such as benzene or toluene can be employed.
The condensation to form the imine proceeds rapidly at a temperature between about 25C and 65C in the presence of a drying agent or during azeotropic removal of water.
Examples of 3-arylacroleins which can be used are represented by the formula HC-CH=CH-R' -wherein R' is phenyl, Cl-C4 alkylphenyl, Cl-C4 alkbxy-phenyl, halophenyl, furyl or naphthyl. Examples of such aldehydes are cinnamaldehyde, 4-methylcinnaldehyde, 3~ethylcinnamaldehyde, 4-ethoxycinnamaldehyde, 3-methoxy-cinnamaldehyde, 3-t-butyloxycinnamaldehyde, 3-ethoxycin-namaldehyde, 3-bromocinnamaldehyde, 2-(2-furyl)acrolein, 2-(2-naphthyl~acrolein, and like aldehydes.
Examples of benzylamines useful in the imine formation are benzylamine and the C1-C4 alkyl, Cl-C4 alkoxy, and halo-substituted benzylamines such as 4-methylbenzylamine, 3-chlorobenzylamine, 3,4-dichloro-benzylamine, 4-methoxybenzylamine, 2-bromobenzylamine, 3-ethylbenzylamine, 3,4-dimethylbenzylamine, 2,4-di- -methylbenzylamine, 4-chloro-3-methylbenzylamine, 4-iso-propylbenzylamine, 4-t-butylbenzylamine, and the like.
The imine 6a can be employed in the cyclo- ~ ~;
30 addition reaction without prior isolation. For example, ~ --the reaction mixture in which the imine is prepared may be used directly in the cycloaddition to form the `~
azetidinone 1.

1332~59 :

The azetidinone represented by the formula 1,wherein Y is -CH=CH- and R' is a m-alkoxyphenyl group, is a valuable intermediate in a process provided by this invention for the asymmetric preparation of l-carba- -~
cephalosporins. In particular the process comprises the preparation of l~carba-3-hydroxy-3-cephem-4i-carboxylic -acid esters. ~:
According to the process the (S)-4-aryloxa- ;~ :
zolidin-2-one-3-ylacetyl halide (5a) is reacted in ~he cycloaddition reaction described above with the imine (6a), formed with a benzylamine and a m-alkoxycinnamal- ~
dehyde, to provide the azetidinone represented by the ~;;; .
formula 1 wherein Y is -CH=CH- and R' is a m-Cl-C4 alkoxyphenyl group. The azetidinone 1 is hydrogenated to the corresponding 4~-[2-(m-alkoxyphenyl)ethyl]-azetidinone, and the latter is reduced with lithium- .~
ammonia in the presence of t-butyl alcohol to effect .~:-reduction of the phenyl ring, removal of the chiral ' :.
auxiliary and the l-benzyl group to provide a 3~-amino~
4~-[2-(5-alkoxycyclohex-1,4-dienyl)ethyl]azetidinone. : -The 3-amino group of the azetidinone is protected with .
a conventional amino-protecting group and the 3~-pro~
tected-aminoazetidinone is subjected to ozonolysis to :~
yield the ~-keto ester Cl-C4 alkyl 5-[3~-(protected :
amino~azetidin-2-one-4~-yl]-3-oxopentanoate.
The ~-keto ester ozonolysis product is con~
verted to the a-diazo derivative and the diazo derivative ~ ;:
is cyclized with Rhodium (II) to provide the 3-hydioxy~
l-carbacephalosporin ester. ~ :
One specific embodiment of the process is illustrated in the following reaction scheme, where "alk" represents Cl-C4 alkyl.
~',, '~

.

` :"`
13320~g sa + /~ a R~ \0-alk Ar .~
Ar H2, ~7 ~HzCHz_~ 1 (y --^H CH

¦ Li, NH3 l t-C~HsOH

H2 ~ f H2CH2 _ ~ ~- 7a ~H 0-alk . acylata :~
_ .
R1CON ~ ~ H2CH2 ~ aa ~- H 0-alk .
l û3 O ~ i --R1CON ~ ~CH2CH2~-CH2-_C0-alk ~a ~ H
' ~'' 1332~9 It will be appreciated with reference to the foregoing reaction scheme that the imine 6a is struc- ~' turally selective in the process. The m-alkoxyphenyl group of the imine ultimately provides the alkyl ~-ketoester 9a via oæonolysis of the 5-alkoxycyclohexa-1,4-diene 8a which in turn is provided by the lithium in ammonium reduction of 1 wherein Y = -CH2-CE2~
According to this process the azetidinone 1 (Y = -C~=CH-) is hydrogenated over a palladium catalyst such as a supported palladium catalyst, ~ , 5% or 10%
palladium on carbon, barium carbonate, or other suitable ~-support. The reduction can be carried out at atmospheric pressure, or at somewhat elevated pressures, in an inert solvent at room temperature. Inert solvents such as methylene chloride, di- or trichloroethane, tetra-hydrofuran, methyl alcohol, ethyl alcohol, or ethyl ~
acetate may be used. ~-The 4~-[2-(m-alkoxyphenyl)ethyl]azetidinone is reduced to the 3~-amino-4~-[2-(5-alkoxycyclohex-1,4-dienyl)ethyl]azetidin-2-one (7a) with lithium in liquid ammonia containing t-butyl alcohol. The reduction is carried out at a temperature between about -30C and about -90C and preferably at between about -70C and about -80C. The reduction is carried out by dissolv~
ing lithium in liquid ammonia and cooling the solution to a range of about -50C to about -90C. An excess of t-butyl alcohol is added followed by the addition of a -solution of the azetidinone in an inert solvent. The solution of the azetidinone may contain t-butyl alcohol as a cosolvent. Suitable solvents for the azetidinone include tetrahydrofuran, dimethoxyethane, or like solvent.

,~,, . ". j, .. .. . . .. ~ , . ... .

~ - ~ ~
-` 13320.59 After the solution of the azetidinone is added, the reduction mixture is stirred for about 30 minutes to about 2 hours. On small laboratory size reactions, the reduction is allowed to stir in the cold for about 30 minutes while with large scale reductions in manufacture somewhat longer reduction time may be re~uired for complete reduction to the diene 7a.
The reduction effects the removal of the chiral auxiliary moiety, incorporated via the cyclo-addition with 6a, leaving the 3-amino group. The reduction also effects removal of the l-benzyl or 1-substituted benzyl group.
The 3-aminoazetidinone 7a can be isolated from -~
the reduction mixture and used in the next step after ;~
amino group protection as shown in the reaction scheme.
Alternatively, and preferably in the process context, 7a is acylated in the same reaction vessel to provide the acylated aminoazetidinone 8a. Although the preced-ing reaction scheme shows only acylation producing an acylamino group of formula RlCONH-, those skilled in the art will immediately appreciate that the 3~-amino func-tion of the intermediate of formula 7a can also be pro-tected with a conventional amino protecting group such as t-butoxycarbonyl. The intermediates of the formula 25 7a and 8a type are novel and, accordingly in a further -~
aspect of the invention there are provided compounds of formula ~IV): -~ ' ~
. ", . ..
~"~

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

1 3 3 2 0 5 9 ! ~
X-6605 -16~

, -' '',' :.
Rs~ f ~CH2CH2 ~ - ,`lH Oa l k :
( IV ) ~ ;

wherein R5 is amino, optionally protected by a conven-tional amino protecting group, or an acylamino group of the formula RlCONH.

wherein R1 is as defined above. ~;~
Following the reduction the reaction mixture is treated with sufficient benzene to discharge the blue ~--color of the mixture. Ammonium acetate is added to the 20 mixture and the bulk of the ammonia is distilled off. -~
The solvent and any remaining ammonia are evaporated.
The residue 7a is treated with a water miscible organic ~;
solvent such as tetrahydrofuran and the mixture or solution is acidified to a pH between about 7 and about `~;
25 9. The solution of 7a is then treated with an acylating -agent to provide the 3~-acylamino-4~-[2-(5-alkoxycyclo- ;~
hex-1,4-dienyl)ethyl]azetidinone 8a. The 3~-amino group is protected to protect its integrity during the subse-~uent ozonolysis step in the process.

"'' ~

,~

13320~9 The acylating agent may be formed with any carboxylic acid, the acyl residue of which is stable in the subsequent ozonolysis step of the process. The carboxylic acid can be,for example,an alkylcarboxylic acid such as acetic acid, propionic acid, butyric acid and the like; an arylcarboxylic acid such as benzoic acid, naphthoic acid, which may be optionally substituted by lower alkyl, lower alkoxy, or halogen; or an aryl-acetic acid such as phenylacetic acid, phenoxyacetic acid, phenylthioacetic acid, and such acids optionally substituted. The desired carboxylic acid for use in the acylation is converted to an active derivative such as the acid chloride, acid anhydride or anhydride formed with a halo formate such as a Cl-C4 alkyl chloroformate, ~g~ ethyl chloroformate and iso-butyl chloroformate.
The acylating agent can be an aryloxycarbonyl halide such as benzyloxycarbonyl chloride or p-nitrobenzyloxy- ~`
carbonyl chloride.
Preferred acylating agents are represented by ;~
20 the formula ;~ ~
O ~;-.:
Rl-C-W ~,' .
wherein Rl is Cl-C6 alkyl; a phenyl group i a ~==~
~ ;

~' ~,' "''' ~'~:''',~',' ''"''''~''''' ;; '~

1332059 :

X-6605 -18~

wherein a and a' independently are hydrogen, C1-C4 alkyl, C1-C4 alkoxy or halogen; a group represented by the formula ;
S ~ ~ ~z) ~ H~

wherein Z is 0 or S, m is 0 or 1, and a and a' have the ;
10 same meanings as defined above; or Rl is R10 wherein `~
Rl represents Cl-C4 alkyl, C5-C7 cycloalkyl, benzyl, ~ :
nitrobenzyl, methoxybenzyl, or halobenzyl; and W is .. :~
chloro, bromo, or an anhydride forming group represented :
by the formula ll O C Rl, ~ .`~ , `
wherein Rl has the same meanings as defined above. ;: ::.
Examples of acyl halides represented by the . ~
above formula are acetyl chloride, acetyl bromide, butyryl chloride, propionyl chloride, benzoyl chloride, 4-chlorobenzoyl chloride, 4-methylbenzoyl chloride, :~
phenoxyacetyl chloride, 4-chlorophenoxyacetyl chloride, phenylacetyl chloride, 3-ethylphenylacetyl bromide, phenylmercaptoacetyl chloride, 4-chlorophenylmercapto~
acetyl chloride, benzyloxycarbonyl chloride, cyclohexy-oxycarbonyl chloride, cyclopentyloxycarbonyl chloride, lethoxycarbonyl chloride, and the like.
Examples of anhydrides represented by the ;-above formula are benzoic acid anhydride, phenoxyacetic ;',~: ', ' '';~'~ ''-' ;;~ '' 1. ~ 3 2 0 ~ !

acid anhydride, phenylacetic acid anhydride, p-chloro-phenoxyacetic acid anhydride, phenylmercaptoacetic acid anhydride, di-t-butyl dicarbonate, dibenzyl dicarbonate, di-(p-nitrobenzyl) dicarbonate, di-ethyl dicarbonate, 5 di-cyclohexyl dicarbonate, and like anhydrides. ::
The N-acylated reduction product 8a is re-covered from the mixture by extraction and is purified by chromatography over silica.
In an alternative to the above described preferred one-pot conversion of l(Y = -CH2CH2-) to 8a, compound 1 is reduced with lithium in liquid ammonia without added t-butyl alcohol to provide the 3-amino-azetidinone represented by the formula . .
H H

H2Nr b~ Ik .
Acylation of the 3~-amino group with the desired car- :~
boxylic acid or amino-protecting group followed by re-duction with lithium in liquid ammonia in the presence~:.
of excess t-butyl alcohol provides the 5-alkoxycyclohex-~; 25 1,4-diene 8a.
Preferably the above-described alternative `
- reduction with lithium in ammonia is carried out by usin~ only about 3 equivalents of t-butyl alcohol rather than an excess. When the reduction is carried out with ~ -3 equivalents of t-butyl alcohol over a short reaction ,: '- ' ~ :' ;'"'':
.':~,'. .',',...

, ';` '' 1 3 3 2 0 5 9 `:

X-6605 -20- , time the aromatic phenyl ring remains intact while the "
chiral auxiliary and N-benzyl group are removed. When `
the reduction is carried out as described above without ,, added t-butyl alcohol incomplete removal of the 1-benzyl,`, 5 group and the chiral auxiliary can result. , ,`, The 3-acylaminoazetidinone 8a, obtained by either route, is then converted to the ~-keto ester 9a'~ ,, by oæonolysis. The ozonolysis is preferably car,ried out in 50% methyl alcohol in dichloromethane or other suit-, , 10 able solvent mixture, at a temperature between about -5C~, and about -80C. The ozone is passed into the solution of the diene 8a until the reaction is complete. The~ '~
ozone is most conveniently obtained from a conventional ozone generator in a stream of air. The completion of the ozonolysis may be determined by the use of a diene indicator such as solvent red ("Sudan III", Aldrich ,,~
Chemical Company). Following completion any ozonide ' and excess ozone is destroyed in the cold with dimethyl -;, -'' sulfide or other suitable reducing agent such as a 20 sulfite or phosphite and the product 9a is recovered ~' from the mixture. For example, the reaction mixture is~
allowed to warm to room temperature, is poured into ' ' brine and the product is extracted with a water immiscible solvent such as methylene chloride. The 25 ~-keto ester 9a may be further purified by chroma- ~ ' tography over silica. , , The ~-keto ester 9a is then converted to the 7-acylamino-1-carba(1-dethia)-3-hydroxy-3-cephem ester lla via diazo compound lOa, and cyclization of the diazo ~ ; ,;
30 ester to the 1-carbacephalosporin with Rhodium (II). ~ ' ;
'.

* Trade mark ~3320n~j9 sa ~.

R1 CONI~CHzCHz~--COOa I k 0~ H 1 oa Rh ( II) Rl CONI~

~ H
t 1 la COOalk The ~-keto ester 9a is best converted to the diazo ester lOa in an inert solvent such as acetonitrile, --dichloromethane, trichloroethane, or the like, with p-toluenesulfonyl azide (tosyl azide) in the presence of ~ hindered tertiary amine, e.q., diisopropylethylamine.
The reaction is conveniently carried out at room tempera~
ture. Generally the tosyl azide is used in an excess of 25 the stoichiometric amount while the amine is used in an ~;
amount of about one-fourth of the stoichiometric amount. ;-^~
The diazo ester can be recovered from the reaction mix~
ture by partitioning the mixture between a water lmmiscible solvent such as methylene chloride and brine containing 30 some tartaric acid or citric acid. The diazo ester is ~ `
.':
i"'~.'',''.'' ",','' 1 3 3 2 0 r~ 9 obtained in purified form from the extract via chroma-tography over silica and recrystallization.
The ester moiety "alk" of 10a becomes the ester group of the 1-carbacephalosporin lla upon cycliza-tion as shown in the reaction scheme. Ester groups suchas the lower n-alkyl groups, e.q., methyl, and ethyl, are less readily removed form the carboxy function than~ ~;
other groups. From synthetic point of view, it may be desirable to form a l-carbacephalosporin lla wherein the 10 ester group is a conventional carboxy-protecting group ;
more readily removed than methyl or ethyl. A further aspect of this invention provides a process for the transesterification of the ester group ~alk) of 10a to diazo ester 10b as shown below.

RlCON CHz-CH2 ~ ~ -C00alk ~ ~ 2 10a ;~ ;
0~ ¦ RzOH
1 Ti(OR2)4 : ~

R1CON ~ CH2CH2~ -C00R2 10b ~ :

~ H
~ :
wherein R1 and alk have the previously defined meanings and R2 is allyl, 2,2,2-trichloroethyl, 2,2,2-tribromo-ethyl, ~-tri(Cl-C4 alkyl)silylethyl, benzyl, Cl-C4 alkyl-benzyl, Cl-C4 alkoxybenzyl, nitrobenzyl, or chlorobenzyl.
Other ester groups conventionally used to protect the 4-carboxylic acid function of cephalosporins can simi-larly be introduced in the compound of formula 10b.

~.,. " ... ~... .... .... . . .

The process is carried out by mixing an excessof the alcohol, R2OH, with titanium tetraisopropoxide and removing isopropyl alcohol by evaporation. The diazo ester, 10a, is added to the solution of the S Ti(oR2)4 in excess alcohol, and an inert solvent if necessary, and the solution is maintained at a tempera-ture between about 25C and about 45C until trans-esterification is complete.
Inert solvents which may be used are, for ~ -example, methylene chloxide, di- or trichlorethane, chloroform, acetonitrile, tetrahydrofuran, or dioxane. ~
When benzyl alcohol is used in the process to form the ~ -R2 ester group it also may serve as a solvent for the ~-process. ; -;
Once again, although the 3~-amino function of the intermediates of formula 9a, 10a and 10b is shown as being protected by a group of formula RlCO, those skilled in the art will appreciate that other conven~
tional amino protecting groups such as t-butoxycarbonyl can similarly be used. Thus, in accordance with a further aspect of the present invention there are pro-vided compounds of formula (V)~
H H
R6NH~ CH2CH2 ~ OR2 wherein R6 is as defined as a conventional amino pro- ~
30 tecting group or a group of formula RlCO, where R1 is ~ ;
as defined above.
~''' ' '..,',~,~

;`''' '''`'', '',,''"', .,...,.,.,,. "

13320i~9 '' The diazo ester lOa or the diazo ester lOb obtained via the transesterification process can then be cyclized to a l-carbacephalosporin of the lla type (or the R2 derivative) with a rhodium (II) salt, pref-erably the acetate, conveniently in chloroform at thereflux temperature. The reaction can be accomplished by heating for about 15 minutes to about one hour. Typical reaction temperature may vary from 0 to 100C. The 7- ;
acylamino-3-hydroxy-1-carba(1-dethia)-3-cephem-carboxylic -acid ester can be recovered as such from the reaction mixture or may be converted to a derivative which is then isolated.
Again, the reaction schedule depicts only the preparation of 3-hydroxycarbacephem derivatives in which ~ ;
15 the 7-amino group is substituted by R2CO, obviously, the ;~
7-amino group can be protected by other conventional amino protecting groups.
The 3-hydroxy l-carbacephalosporin ester may be recovered from the reaction mixture by first diluting the mixture with water or brine, acidifying the mixture, and then extracting the mixture with a solvent such as ethyl acetate or methylene chloride. The extract is washed, dried and evaporated to provide the product.
The product may be further purified by chromatography and recrystallization.
The cls-enantiomer of the type depicted as lla above is novel and accordingly in a further aspect of the invention there is provided a compound of formula (X):

R6~
~ r~

~ OH
,COF~ , wherein R6 is hydrogen; a conventional amino protecting :: :
group; or a group of formula R1CO whe~e R1 is Cl-C6 alkyl;
10 a phenyl group ~-~::: .

X
a .; . .. :~
wherein a and a' independently are hydrogen, Cl-C4 alkyl, .
Cl-C4 alkoxy or halogen; a group represented by the fonmula ~ :.

~ ;~ m ~
a wherein Z is O or S, m is O or 1, and a and a' have the 2S same meanings as defined above; or R1 is R10 where~n Rl represents C1-C4 alkyl, C~-C7 cycloalkyl, benzyl, nitrobenæyl, methoxybenzyl, or halobe~z~
wherein R2 represents a conventional car~oxy protecting -~ group; ~-or an acid-addition salt the_eof.

This aspect of the invention is also disclosed, ;
and is claimed, in Canadian Patent Application No. 513,971 of David A. Evans et al., filed July 16, 1986, of which the present application is a divisional.
~,~"..

,, , X-6605 -26- 1 3 ~ 9 : ~

The chiral form of the type depicted as lla above is of particular value since it is this enantiomer, and this enantiomer alone, which can be converted to the pharmacologically useful antibiotics of the type :
described in EPl4476; ~ee al~o our Canadian Patent Application Serial No. 513,962, filed July 16, 1986, now Canadian Patent No. 1,262,356, granted October 17, 1989.
In a preferred em~odiment of the process L-phenylglycine (la, Ar=phenyl) is converted to the ethylcarbamate with ethy.l chloroformate, the carbamate ~ :
10 acid is reduced with borane-dimethyl sulfide to L-l- -.
ethoxycarbonylamino-l-phenylethanol (3a, alk=ethyl), and the F~henylethanol is cyclized with n-butyllithium to (S)-4~phenyloxazolidin-2-one 4a. The latter is converted ~;
to 5a via alkylation with ethyl bromoacetate, saponifi~
cation, and treatment of the acid with oxalyl chloride.
The (S)-4-phenyloxazolidin-2-one-3-ylacetyl .
chloride is condensed with the imine formed with benzyl~
amine and m-methoxycinnamaldehyde (form 6a, alk=methyl, R=phenyl) to form the azetidinone 1, Ar=phenyl, alk=methyl). ~:
20 Catalytic reduction of 1 over 5% Pd-C provides l, (Y = -CH2-CH2-) which on reduction in lithium in liguid ammonia ;
and t-butyl alcohol yields the 3-aminoazetidinone (7a, alk=methyl). Without isolation, the 3-aminoazetidinone is acylated with di-(t-butyl) dicarbonate to form the :~
25 3-t-butyloxycarbonylaminoazetidinone (8a, R1 = t-butyl- :
oxy, alk = methyl). Ozonolysis of the 3-t-BOC amino :: :
protected diene product in 50% methyl alcohol in di-chloromethane provides the ~-keto methyl ester 9a. The ~-~-keto methyl ester is reacted in acetonitrile with :
tosyl azide in the presence of diisopropylethylamine ~;

,~ .

to provide the diazo methyl ester (lOa, Rl = t-butyloxy, alk = methyl). The transesterification of the diazo methyl ester to the corresponding benzyl ester is carried out in excess benzyl alcohol with titanium tetra-isopropoxide with heating at about 36C for 42 hours. The diazo benzyl ester is treated in refluxing chloroform with rhodium (II) acetate to provide benzyl ~ ~-7~-(t-butyloxycarbonylamino)-3-hydroxy-1-carba(l-dethia)-3-cephem-4-carboxylate.
10In another embodiment of the process L-phenyl-glycine is converted to 3~-(4(S)-phenyloxazolidin-2-one-3-yl)-4~-[2-(m-methoxyphenyl)ethyl]-1-benzylazetidin-2-one, the latter reduced with lithium in liquid ammonia and t-butyl alcohol and the reduction product, 3~-amino- -~
154~-[2-(5-methoxycyclohex-1,4-diene)ethyl]azetidin-2-one -(7a, alk = methyI) without isolation is acylated with phenoxyacetic acid anhydride. The 3~-phenoxyacetylamino-azetidinone is then converted, as described above for the t-BOC amino-protected azetidinone, to benzyl 7 phenoxyacetylamino-3-hydroxy-1-carba(l-dethia)-3-cephem-4-carboxylate.
The azetidinone represented by the formula 1, -~
wherein Y is -CH=CH- and R' is furyl, also is useful as -~
" ~ .
an intermediate in the preparation of l-carbacephalo-sporins. Accordingly, this intermediate is hydrogenated in a suitable solvent to the corresponding 3~-(2-furyl-ethyl)azetidinone (formula 1, Y= -CH2-CH2-, R' = furyl) over 5% palladium on carbon. The hydrogenation product is converted to the l-carbacephalosporin as shown in the ~ollowing scheme ~`",,',' :~," ~
, ~, .

13320.~9 X-6605 -28- :

Li, NH3, t-C~HsOH

H2~ ~ 2CHz~ 2 o ~ 1 , RsNY ~ CH2CH2~- ~ 13 :~;

H

R~N ~ H2CH2~ 4 ~ ;

l 3 R6N ~ ~ H2CH2COOH

0~ CH2COOR2 DCC
R6NH~ ~ H2CH2COSR7 0~ CH2COOR2 l 2 f t ::;
OH 1~

.. , . ., . , ~ . . .. . . . ..

where R2 is as defined above, preferably "alk", and R7is Cl-C6 alkyl, benzyl or phenyl optionally substituted with Cl-C4 alkyl Cl-C4 alkoxy or halo.
The hydrogenation product is first reduced with lithium in ammonia in the presence of about 3 molar equivalents of t-~utyl alcohol to provide the 3~-amino-azetidinone 12, and the amino group is protected with a conventional protecting group such as the t-butoxy-carbonyl group to yield 13. N-Alkylation of 13 with a 10 reagent of formula X-CH2COOR2 preferably an alkyl halo- -acetate, e.q. t-butyl bromoacetate, affords 14.
Ozonolysis of 14 provides the 2-carboxyethyl N-alkylated protected aminoazetidinone 15. Formation of the thio ester of 15 wi~h the appropriate thiophenol or mercaptan and dicyclohexylcarbodiimide is followed by cyclization to the 3-hydroxy-1-carbacephalosporin ester 17 with lithium hexamethyldisilazane, or a similar hindered base. Hindered bases are strong bases which are non~
nucleophilic to the ~-lactam moiety.
The compound of formula 16 is novel and is provided in a further aspect of the invention.
The 3-hydroxy-1-carbacephalosporin ester 17 can be treated to remove the amino-protecting group to provide the nucleus ester 7~-amino-3-hydroxy-1-carba(l-dethia)-3-cephem-4-carboxylic acid ester. The latter can be acylated with the desired carboxylic acid deriva-tive, e.q. phenylacetyl chloride or phenoxyacetyl chlo-ride, and then treated with diazomethane to form the ~-, 7,B-acylamino-3-methoxy-1-carbaS1-dethia)-3-cephem-4-carboxylic acid ester. The ester is deesterified to yield the free acid antibiotic compound. `

,.., :~
`'' "~-' ..:
'":'-'-',, . ~'`' '' ,.. .

1 3 3 2 !0 ~i 9 The 3-hydroxy-1-carbacephalosporins of formula lla and 17 can also be converted to the corresponding 3-halo derivati~es by the process of our Canadian Patent No.
1,262,356, isRued October 17, 1989.
The azetidinones represented by the formula 1, wherein Y is -CH=CH-, also are useful intermediates in the preparation of the monocyclic ~-lactam antibiotic, 3~-[2-(2-aminothiazol-4-yl)-2-(carboxymethoxyimino)-acetamido]-3~-carbamoyloxymethylazetidin-2-one-1-sulfate, described by U.S. Patent No. 4,502,994. The azetidinone is subjected to ozonolysis to form the 4~-formylazeti-dinone as shown below ;
Ar CH=CH-~

Ar ~CH0 ~5 ' The 3~-~ormyl azetidinone is reduced with sodium boro-hydride to the corresponding 3~-hydroxymethyl substituted azetidinone represented by the formula ~ .

:` ~3320~9 X-6605 -31- ~ -Ar ~ HzOH

0 CH2R :
In the above formulae Ar, R' and R have the :~
same meanings as defined for formula 1.
The 3~-hydroxymethyl compound is reduced with lithium in liquid ammonia containing about 3 equivalents -~
of t-butyl alcohol to yield the 3~-amino-4~-hydroxy- ~:
methylazetidin-2-one represented by the formula i -,.,'- :-.-:
: 15 H2N ~ ~ CH20H

~---NH

The amino group is protected with a conventional amino- ~:.
: 20 protecting group such as the benzyloxycarbonyl group or : : the t-butyloxycarbonyl group and the hydroxy group of ;-~
: . the 4~-hydroxymethyl substituent is protected for ~; ~
:: examp}e by esterification with a lower alkanoic acid , .:
chloride such as acetyl chloride, chloroacetyl chloride, .
or trichloroacetyl chloride. The di-protected compound then is reacted with SO3 in pyridine to for.m the .;
azetidinone represented by the formula :.
P~IH~ CH20--acy 1 ~ ~ 30 T
:~ ~ N-S0~

:"

-` 13320~9 wherein P is a conventional amino-protecting group, acyl is the acyl moiety of a lower alkanoic acid and M~ is an alkali metal cation or a tetraalkylammonium ion such as tetrabutylammonium ion.
The hydroxy-protecting acyl group is removed by basic hydrolysis and the product reacted with an isocyanate to provide the compound represented by the formula C
P~ ~CH20 -~HP' T _ T-~S;)3~ : .
O
wherein P' is for example an acyl group such as tri-chloroacetyl or trifluoroacetyl. Removal OI the amino protecting group P, the carbamoyl N-protecting group P', and reacylation of the 3~-amino group with an active carboxy derivative of a 2-(2-protected-aminothiazol-4-yl)-2-(protected-carboxymethoxyimino)acetic acid provides the di-protected antibiotic. Removal of the protecting groups affords the sulfazecin related antibiotic repre-sented by the formula.
:.

H2~ CHzOC_NH2 `~
-~Cl- CONH
OCH2cOoH g ~S03 ~ :~
:' ' : ~

13320~9 The 4~-formylazetidinone of the above formula also may be converted to the _orrespond1ng 4~-carboxy-azetidinone hy oxidation,e.g.,with chromium trioxide-H2S04 in acetone or with acidic permanganate or other S suitable reagent. The carboxy group may be esterified to a Cl-C4 alkyl ester and the latter reduced with sodium borohydride or lithium aluminum hydride to the 4~-hydroxymethylazetidinone. The 4~-carboxyazetidinone in the form of a lower alkyl ester may be epimerized ~, with a t-alkylamine to the 4a-carboxyazetidinone ester and the latter reduced to the 4a-hydroxymethyl azetidinone.
The epimeric 4-hydroxymethylazetidinones may be converted individually to the 4-halomethyl azetidinone, e.q.,the bromomethyl or iodomethyl derivative and the 15 latter reduced with lithium aluminum hydride to the ~-corresponding epimeric 4-methylazetidinone.
The 4-methylazetidinones thus obtained can be subjected to lithium in ammonia reduction with t-butyl alcohol to remove the chiral auxiliary and the l-benzyl 20 group to provide the 3~-amino-4-methylazetidinone. The -latter is converted by known methods to the monocyclic antibiotic, monobactam, represented by the formula H2~ / ~
~ CON t CH3 OCH3 ,~I-SO

-`- 1332059 .

In a further aspect of this invention there is provided substituted azetidinones represented by the formula Ar ~t r r ~ CH2R
wherein R4 is formyl, carboxy, Cl-C4 alkoxycarbonyl, methyl, halomethyl, or hydroxymethyl and Ar and R have the same meanings as defined for formula 1 above and when R4 is other than formyl, the 4-position epimers thereof.
A preferred group of substituted azetidinones are represented when Ar is phenyl or substituted phenyl, R is phenyl, and R4 is formyl or hydroxymethyl. A pre-ferred compound is l-benzyl-3~-[(S)-4-phenyloxazolidin- ~
2-one-3-yl]-4~-hydroxymethylazetidin-2-one. Another pre- -fPrred compound is 1-benzyl-3~-[(S)-4-phenyloxazolidin-2-one-3-yl]-4~-formylazetidin-2-one. -The intermediates useful in the asymmetric synthesis of the azetidinones of formula 1 described above are also part of the invention. The 4(S)-aryl-oxazolidin-2-one-3-ylacetic acids, esters, and halides represented by the formula 5a are useful in the process as chiral auxiliary forming moieties upon cyclization with the imine 6a to form the azetidinone 1. The chiral auxiliary functions in the process to direct the syn-thesis of 1 to the desired stereo configuration. These .. ~.
''.',,'' ' ; 13320~9 X-6605 -35~

acyl halides, anhydrides, and the ester and acid pre-cursors thereof are represented by the formula :~
, ' '':
~ -CHzCOR3 '1~,l 1 I H ~,~
, ,:
:
10 wherein Ar has the same meanings as defined for formula -1, and R3 is hydroxy, Cl-C4 alkoxy, chloro, bromo, :
trifluoroacetoxy, or -O-P(=O)X2.
Examples of the above intermediates are 4(S)-phenyloxazolidin-2-one-3-ylacetic acid, 4(S)-~4-chloro- :~
phenyl)oxazolidin-2-one-3-ylacetic acid, 4(S)-(4-methyl~
phenyl)oxazolidin-2-one-3yl-acetic acid, 4(S)-(3-methoxy- : ~
phenyl)oxazolidin-2-one-3yl-acetic acid, 4(S)-(2-naphthyl)- :
oxazolidin-2-one-3yl-acetic acid, 4(S)-(2-thienyl) oxazolidin-2-one-3yl-acetic acid, 4(S)-(benzothien-2-yl)-oxazolidin-2-one-3yl-acetic acid, and the Cl-C4 alkyl esters, the acyl chloride and bromide, and the trifluoro~
acetic acid and phosphoryl halide derivatives thereof. ~:
Preferred compounds are represented when Ar is phenyl or .
substituted phenyl, and R3 is t-butyl or chloro. Espe-cially preferred compounds are 4(S)-phenyloxazolidin-2-one-3-ylacetic acid, the ethyl and t-butyl esters and :
the acid chloride thereof. .~:
,, I :
. ~;

The 5-alkoxycyclohex-1,4-dienyl substituted azeti-dinones (formulae 7a and 8a) are also novel intermediates and are represented by the following formula H H
Rs ~ ~ CH2CHz ~ ~-~H ~
a l k wherein R5 is amino or an acylamino group Rl-C0- wherein R1 has the same meanings as defined hereinabove with reference to formula 8a, and alk is Cl-C4 alkyl. In -the above formula alk is preferably methyl.
Examples of RlC0 acyl groups when R1 is an alkoxy, cycioalkoxy or benzyloxy group are ethoxycarbonyl, t-butyloxycarbonyl, cyclopentyloxycarbonyl, cyclohexy-oxycarbonyl, benzyloxycarbonyl, and p-nitrobenzyloxy-carbonyl, and the like. -~
Examples of RlC0 acyl groups when Rl (formula 8a) is other than R1 are phenylacetyl, phenoxyacetyl, phenylmercaptoacetyl, benzoyl, p-chlorobenzoyl, 2,6- ~
dimethoxybenzoyl, 4-chlorophenylmercaptoacetyl, 3,4- ~ -dimethylphenylacetyl, 4-methoxyphenylacetyl, and 3- ~ ~
25 chlorophenoxyacetyl. ~-The 3~-aminoazetidinones of the above formula, ~ -wherein R5 is amino,can form salts with suitable inorganic and organic acids. Examples of such acids are ~
hydrochloric acid, hydrobromic, sulfuric acid and ~;
phosphoric acid, and the alkyl and aryl sulfonic acids ",' ~', `',`,~,'' ','',;' ~' ~."

1332~59 such as a Cl-C4 alkylsulfonic acid, ~g.)methanesulfonic acid and n-butylsulfonic acid; arylsulfonic acids, ~g., benæenesulfonic acid, p-toluenesulfonic acid, p-chloro-phenylsulfonic acid, p-bromobenzenesulfonic acid, and naphthalenesulfonic acid.
The following Examples are provided to further illustrate the invention. In the Examples compound numbers refer to the numbered compounds in the reaction schemes.
PreDaration 1 (S)-4-Phenyloxazolidin-2-one To a stirred, 0C solution of L-phenylglycine (25.3 g, 167.4 mmol) in 60 mL of 3N aqueous NaOH was added ethyl chloroformate (8 mL) in several portions.
Additional 3N aqueous NaOH (35 mL) was add~d to redis-solve the precipitated phenylglycine, followed by ethyl chloroformate (4 mL). This process was continued with 3N aqueous NaOH (65 mL) and ethyl chloroformate (8 mL, total of 20 mL, 209 mmol) over a period of ca. 10 minutes. After stirring for 1 hour at 0C the solution was acidified with 6 M H2SO4, and the precipitated car- ;
bamate was extracted into 8% isopropanol in dichloro-methane (2 X 300 mL). The combined organic layers were dried (Na2SO4) and concentrated to afford 37.3 g of~ ;~
N-ethoxycarbonyl L-phenylglycine as a white solid. The carbamate was dissolved in 170 mL of THF, cooled to 0C, treated with borane-dimethylsulfide (33.5 mL of a 10 M
: . .

~332059 solution), and stirred at room temperature for 17 hours.Excess borane was cautiously quenched with water (100 mL), and the bulk of the THF removed under reduced pressure.
The white slurry was diluted with additional water (350 mL) and then extracted with dichloromethane (2 X
500 mL). The combined organic layers were washed with 100 mL of saturated aqueous NaHC03, dried (Na2SO4), and concentrated to give 27.4 g of (S)-2-ethoxycarbonylamino-2-phenylethanol as a white solid. The crude alcohol was dissolved in 200 mL of THF, cooled to 0C, and treated with n-butyllithium in hexane (6 mL of a 2 M solution).
After heating at 55C for 6 hours, the solution was treated with acetic acid (1 ml) and concentrated. The residue was dissolved in dichloromethane (300 mL), washed with 100 mL of brine, dried (Na2SO4), and con- -centrated to a white solid. Recrystallization from toluene gave 17.14 g (63%) of (S)-4-phenyloxazolidin- ~;
2-one; mp 132-133C; [a]D20 +49.5o (c = 2.1, CEC13);
IR (CHC13) 3460, 3020, 1760, 1500, 1480, 1460, 1400, ~
1230 cm~1; lHNMR ~ 7.45-7.30 (m, 5, ArH), 6.42 (br s, -~-1, NH), 4.96 (br t, 1, J = 7.8 Hz, OCH2CH), 4.72 (t, 1, J = 8.6 ~z, one of OCH2CH), 4.17 (dd, 1, J = 6.7, ~;
8.7 Hz; one of OCH2CH).
Anal. Calcd for CgHgNO2 C, 66.24; H, 5.56.
Found: C, 66.16i H, 5.62.
,;,. .

; . ,~

'"~,:, '.' ; ' 1 .
.. .- .
.,`.'~,' ,,,~,"., ;,~

13320~9 Preparation 2 S)-4-Phenyloxazolidin-2-one-3-y~lacetic acid To a stirred, 0C solution of (S)-4-phenyl-oxazolidin-2-one (1.07 g, 6.54 mmol) in 15 mL of THF was added sodium hydride (O.32 g of a 60% oil dispersion, 8.0 mmol). When gas evolution had ceased (ca. 10 minutes), ethyl bromoacetate (0.~7 mL, 7.8 mmol) was 10 added. After 2 hours at 0C, the mixture was treated .
with 50 mL of 2N aqueous NaOH, stirred rapidly for 1 hour at room temperature, and then partitioned between hexane (50 mL) and water (50 mL). The aqueous layer :~:
was separated, acidified with 6 M aqueous H2S04, and -extracted with dichloromethane (2 X 200 mL). The combined organic phases were dried (Na2SO4) and con~
centrat~d to a thic~ ~il, which was dissolved in 4 mL
of warm toluene, seeded, and allowed to crystallize .:
overnight; filtration gave 1.33 g (92%) of (S)-4-phenyl- - `
oxazolidin-2-one-3-ylacetic acid: mp 106-108C; [~D22+
173 (c = 2.0, CHC13); IR (CHC13) 3500-2500 (v. br), 1760 (br), 1480, 1460, 1430, 1230 cm~l; lH NMR ~ 11.2 :
(br s, 1, COQH~, 7.47-7.25 (m, 5, Ar~), 5.05 (t, 1, J = 8.4 ~z, OCH2CH), 4.72 (t, 1, J = 8.8 Hz, one of ~:
OCH2CH), 4.32 (d, 1, J = 18.4 Hz, one of NCH2), 4.17 (t, 1, J = 8.4 Hz, one of OCH2C~), 3.41 ~d, 1, J = 18.4 Hz, one of NCH2).
Anal. Calcd for C~ 1NO4: C, 59.72; H, 5.01.
Found: C, 59.83; H, 5.00.
~; 30 , ~

13320~9 PreParation 3 ~

(S)-4-~henYloxazolidi ~ ylacetYl .,;~:.
chloride: A 250 mL round bottom flask fitted with a reflux condenser and a CaS04 drying tube was charged with (S)-4-phenyloxazolidin-2-one-3-ylacetic acid (5.3 g, 23.96 mmol) and 60 mL of toluene. The suspen-sion was treated with oxalyl chloride (3.2 mL, 36.7 mmol) and stirred at 60C for 3 hours. ~t this point gas evolution had ceased and the reaction was homo~
geneous. Removal of solvent under reduced pressure ;
afforded the title acid chloride as a thick oil.

Preparation 4 -~

PreParation of imine formed from benzYlamine and 3-methoxvcinnamaldehvde: To a solution of 3 methoxy~
. .., .~
cinnamaldehyde (4.27 g, 26.33 mmol) in 40 mL of toluene was added benzylamine (2.73 mL, 25.01 mmol). The solu-tion was warmed briefly to ca. 40C, and upon cooling became cloudy from released water. Argon flushed 4A ;`
molecular sieves (18 g, freshly activated) were added and the mixture was allowed to stand at room temperature ~`~
for 16 hours. This solu~ion of imine was used directly 25 in the subsequent cyclization. ;~`

Example 1 Formation of l-benzYl-3~[(S)-4-PhenYloxazoll-din-2-one-3-yl1-4~-~3-methoxystYryl ? azetidin-2-one:
The oxazolidinone acid chloride was dissolved in dichloromethiane (70 mL), cooled to -78C, and treated withi triethylamine (S.0 mL, 35.9 mmol). A fine, heavy precipitate formed over 15 minutes. To this mixture was added, via cannula, the toluene solution of the imine prepared as described above. The sieves from thie imine solution were washed with dichloromethiane (2 X 10 mL), and each wash added to the reaction. The cold bath was removed, the reaction warmed and maintained at 0C for 2 ;-hours. The mixture was poured into 200 mL of dichloro~
, methane, washed with 0.5 M tartaric acid and saturated aqueous Na~C03 (50 mL each), dried (Na2S04), and concen-trated to a reddish oil. Crystallization from ca.
lS0 mL of 30% hexanes in ethyl acetate gave 6.87 g of the title compound as white needles. Chromatography of the mother liguor on 170 g of silica with 20% ethyl acetate in dichloromethane gave an additional 1.9 g of the azetidi~one (total 8.77 g, 80%). The minor isomer was obtained by further elution with 40% ethyl acetate in dichloromethane and was then purified by chromatog-raphy on silica with 30% hexanes in ethyl acetate.
Major isomer, the title compound: mp 142-143C;
[~]D22+ 46.4 ~c = 1.0, CHCl3); IR (CHC13) 3020, 1760, ;~
1600, 1410 cm~l; lH NMR (CDCl3) ~ 7.45-6.75 ~m, 14, ArH), 6.45 (d, 1, J = 16 Hz, ArC~=CH), 5.81 (dd, 1, J = 16, ~;~
8.9 Hz, ArCH=CH), ~.88 (dd, 1, J = 8.9, 7.4 ~z, OCH2CH), :

' ~

13320~9 4.61 (t, 1, J = 8.9 Hæ, one of OCH2CH), 4.55 (d, 1, J = 5 Hz, C3H), 4.53 (d, 1, J = 14.7 Hz, one of ArCH2), 4.23-4-12 (m, 3, one of ArCH2, one of OCH2CH, C4H), 3.82 (s, 3, OCH3) Anal. Calcd for C28H26N204: C, 73.99; H, 5.77.
Found: C, 74.06; H, S.74.

Exam~le 2 By using the method described in Example 1, the imine prepared from benzylamine and cinnamaldehyde, and 4(S)-phenyloxazolidin-2-one-3-ylacetyl chloride there was prepared 1-benzyl-3~-[4(S)-phenyloxazolidine~
2-one-3-yl]-4~-styrylazetidine-2-one: mp 186.5-187.5C;
t~]D22= +56.9 (C = 1.7, CHC13); IR (CHC13) 3010, 1760, 1500, 1460, 1410 cm-1; lH NMR (C~C13) ~ 7.45-7.10 (m, 15, ArH), 6.48 (d, 1, J = 16 ~z, CH=C~-Ar), 5.87 ~dd, 1, J = 9, 16 Hz, CH-CH-Ar), 4.88 (dd, 1, J = 7.4, 8.9 Hz, OCH2CH), 4.61 (t, 1, J = 8.9, one of OC~2C~), 4.55 (d, `^~
1, J = 16 Hz, one of ArC~2), 4.54 (d, 1, J = 4.7 Hz, C-3 H, overlaps with doublet at 4.55), 4.21 (dd, 1, J = 4.7, 9.0 Hz, C-4 H), 4.17 (dd, J = 7.4, 8.9 Hz, one of OCH2CH), ~;~
- 4.14 (d, 1, J = 16 ~z, one of ArCH2).
Anal. Calcd. for C27H24N2O3: C, 76.39; H, 5.70.
Found: C, 76.53; H, 5.69.
. : .
Example 3 By using the method described in Example 1, the imine prepared from benzylamine and 3-(2-furyl)-acrolein was condensed with 4(S)-phenyloxazolidin-2-one-:
13320~9 3-ylacetyl chloride to provide 1-benzyl-3~-[4(S)-phenyloxazolidine-2-one-3-yl]-4~-[2-(2-fuxyl)ethenyl]-azetidine-2-one: mp 181 182C; [a]D20= +13.6 (c = 1.6, CHC13), IR (CHC13) 3020, 1760, 1660, 1500, 1460, 1410 cm~l; lH NMR (CDC13) ~ 7.45-7.07 (m, 11, ArH), 6.39 (dd, 1, J = 1.8, 3.3 Hz, OCH=CH), 6.27 (d, 1, J = 16 Hz, N-CH-CH=CH), 6.25 (d, 1, J = 3.3 Hz, O-C=CH), 5.75 (dd, 1, J = 16, 8.9 Hz, N-CH-CH=CH), 4.91 (dd, 1, J = 8.8, 7.4 Hz, OCH~CH), 4.65 (t, 1, J = 8.9 Hz, one of OCH2CH), 4.61 (d, 1, J = 15 Hz, one of ArCH2), 4.55 (d, 1, J = 4.8 Hz, C-3 H), 4.20 (dd, 1, J = 7.4, 8.8 Hz, one of OCH2CH), 4.11 (dd, 1, J = 4.8, 8.9 Hz, C-4 H), 4.02 (d, 1, J = 15 Hz, one of ArCH2).
. r C25H22N2O4: C, 72.44;
H, 5.35. Found: C, 72.44; H, 5.41.

Example 4 l-Benzyl-3~-[~S~-4-~henyloxazolidin-2-one-3-~11-4~-[2-(3-methoxyphenYl)ethYl]azetidin-2-one The 3-methoxystyryl substituted azetidinone prepared as described in Example 1 (0.552 g, 1.22 mmol) was hydrogenated (balloon pressure) in dichloromethane (20 mL) over 0.052 g of 5% Pd on carbon for 3 hours at room temperature. Filtration through "Celite"*and removal of solvent under reduced pressure afforded 0.555 g ; '(100%) of the corresponding 4~-[2-(3-methoxyphenyl)-ethyl]azetidinone (compound 8) as a white solid. Re-crystallization from hexanes-ethyl acetate gave long * Trade mark for diatomaceous (infusorial) earth and filter aids made therefrom.

13320~9 ~

needles: mp 134-135C; [~]D23 +3~.6 (c = 2.2, CHCl3);
IR (CHC13) 3010, 1755, 1605, 1590, 1410 cm~l; lH NMR
~ 7.44-5.42 (m, 14, ArH), 4.97-4.84 (br t, 1, OCH2CH), 4.68 (t, l, J = 9 Hz, one of OCH2), 4.64-4.59 (br d, 1, C3H), 4.32 (s, 2, ArCH2), 4.27 (dd, l, J = 6.4, 9.0 H~, one of OCH2), 3.77 (s, 3, OCH3), 3.57 (dt, 1, J =
6.6, 4.9 Hz, C4H), 2.36 (br t, 1, J = 8 Hz, ArCH2CH2), 1.56-1.44 (br q, 1, ArCH2CH2).
Anal. Calcd for C20E24N4O6 Found: C, 73.48; H, 6.11.

ExamPle 5 Methyl 5-f3~-(t-butYloxYcarbonylamino)azetidin-2-one-4~-Yl]-3-oxopentanoate Lithium wire (O.548 g, 79 mmol) was added to 55 ml of ammonia at -78C and the mixture was warmed briefly to affect solution of the metal and then recooled to -78C under positive argon pressure. The dark blue solution was first treated with tert-butanol (12 mL).
A solution of the l-benzyl-3~-(4-phenyloxazolidin-2 one-3-yl)-4~-[2-(3-methoxyphenyl)ethyl] azetidin-2-one ~`~
(2.36 g, 5.17 mmol) in THF:tert-butanol (24 mL of a 3:1 mixture) was then added via cannula over a period of 5 minutes. After stirring for exactly 30 additional minutes, dry benzene (2 mL) was added. The blue color `
! - discharged after ca. 1 minute. Ammonium acetate ~' (6.08 g, 79 mmol) was added, the cold bath removed, and the bulk of the ammonia was distilled off through a . . .
.',, ' , '., .....

. ',; .:
'.'': '' ~' 133~0~9 mercury bu~bler. Solvent and any residual ammoniawere removed under reduced pressure at 40C. The re-maining white solid was suspended in 50 mL of THF:H20 (1:1), acidified to pH 8 with 3N ~C1, and treated with di-tert-butyl dicarbonate (1.8 mL, 7.8 mmol). The two phase mixture was stirred rapidly for 12 hours and then partitioned between dichloromethane (200 mL) and H2O ~;:
(50 mL). The aqueous phase was reextracted with dichloromethane (50 mL) and the combined organic phases 10 were washed with 50 mL of saturated agueous NaHCO3, -dried (Na2S04), and concentrated. Chromatography of the residue on 110 g of silica with 40% hexanes in ethyl acetate afforded 1.23 g of the partially purified dihydroaromatic 3~-t-butyloxycarbonylamino-4~-[2-(5-methoxycyclohex-1,4-diene)ethyl]azetidine-2-one as a waxy solid.
The diene product was dissolved in 25 mL of 50% methanol in dichloromethane, treated with one drop of pyridine and ca. 1 mg of "Sudan III"* dye(Aldrich Chemical Co.), and ozonolyzed at -78C until the red color discharged. ~imethyl sulfide (3 mL) was added, the cold bath removed, and the reaction mixture stirred at room temperature for 5 hr. The light orange solution was poured into 100 mL of brine and extracted with dichloromethane (1 X 200 mL, 1 X 50 mL). The combined ~`
organic layers were dried (Na2S04) and concentrated.
Chromatography of the residue on 65 g of silica with 7%
isopropanol in dichloromethane afforded methyl 5-[3~-(t-butyloxycar~onylamino)azetidin-2-one-4~-yl]-3-oxo-pentanoate (0.97 g, 60% from 8) as an off white solid.

:
* Trade mark ~ .

1 3i320.S9 Recrystallization from toluene gave colorless needles:
mp 122-123~C; [a]D20 +48.6 (c = 1.4, CHC13); IR (CHC13) 3430, 3420, 3340 (br), 3020, 2990, 1770, 1720, 1510, 1370, 1250, 1160 cm~1; 1H NMR (CDC13) ~ 6.51 (br s, 1, N~ of ~-lactam), 5.50 ~br d, 1, BocN~, S.05-4.98 (m, 1, C-3H), 3.83-3.71 ~m, 1, C-4H), 3.75 (s, 3, OCH3), 3.48 (s, 2, COCH2CO), 2.74-2.56 (m, 2, CH2C~2CO~, 1.93-1.74 (m, 2, CH2CH2CO), 1.45 (s, 9, tert-butyl).
n 1. Calcd- for C14H22N26 C~ 53-49;
H, 7.06. Found: C, 53.56; H, 7.11. ;~

The 3-t-BOC-aminoazetidinyl ~-keto ester pre~
pared as described above was then converted to the 3-hydroxy-1-carba(1-dethia~-3 cephem ester by the procedures of the following Example 6.

Example 6 --BenzYl 7~-(t-butyloxycarbonylamino)-3-hydr 1-carba(l-dethia)-3-ce~hem-4-carboxylate ; A. Diazo Transfer To a 0C solution of the ~-keto ester (1.13 g, ~`25 3.6 mmol) in 10 mL of acetonitrile was added ~-toluene- ~-sulfonyl azide (3.6 mL of a 1.5 M solution in dichloro- ; -methane) and diisopropylethylamine (0.13 mL, 0.75 mmol).
1: . I , The reaction was covered with foil, stirred at room `
temperature for 2 hours, and then partitioned between -dichloromethane (100 mL) and brine (50 mL) containing 13320~9 X-6605 -~7-10 mL of 0.5 M tartaric acid. The aqueous layer was reextracted with dichloromethane (50 mL) and the com-bined organic layers dried (Na2SO4) and concentrated.
Chromatography of the residue on 100 g of silica with 5%
isopropanol in dichloromethane afforded 1.15 g (94%) of the diazo keto ester as a white solid. Recrystalliza-tion from ethyl acetate-hexanes gave small needles: mp 136-137C (dec); [a]D20 +65.8 (c = 0.6, CHC13); IR
(CHC13) 3440, 3420, 3360 (br), 3020, 2990, 2150, 1770, 1720, 1650, 1510, 1440, 1370, 1320, 1160 cm~l; 1H NMR
~ 6.49 ~br s, 1, NH of ~-lactam); 5.46 (d, 1, J = 8.6, BocNH); 5.06 (dd, 1, J = 4.8 Hz, 8.1 Hz; C3H); 3.85 (s, 3, OCH3); 3.85-3.78 (m, 1, C4H); 3.06-2.82 (m, 2, `
CH2CH2CO); 2.0-1.7S (m, 2, CH2CH2CO); 1.45 (s, 9, tert-15 butyl).
Anal- Calcd- for C14H20N46 C~ 49-40; ~
H, 5.92. Found: C, 49.47; H, 5.93. -B. Transesterlfica ion A solution of benzyl alcohol (20 mL, 193 mmol) and titanium isopropoxide (0.78 mL, 2.62 mmol) was stirred under vacuum (1 mm ~g) for 45 minutes to remove isopropanol. The flask was covered with foil, vented ~-25 to argon, and the diazo ~-~eto methyl ester (0.953 g, ~`
2.80 mmol) was added. the solution was heated at 36C
for 42 hours, diluted with 60 mL of diethyl ether, and treated with saturated aqueous Na2SO4 (3 mL). The mixture was stirred rapidly overnight, and then filtered through a pad of "Celite"*. After removal of ether on a * Trade mark -~

~:

~3~32059 rotary evaporator, the benzyl alcohol was dlstilled off using a kugelrohr oven (15 millitorr, 50C). Chroma-tography of the residue on 100 g of silica afforded the corresponding diazo ~-keto benzyl ester (0.837 g, 72%) as a white solid: mp 152-153 (dec); [~]D20 ~55.6 (c =
0.7, CHC13); IR (CHCl3) 3450, 3420, 3350 (br), 3020, 2990, 2150, 1770, 1715, 1655, 1510, 1370, 1305, 1165 cm~l; lH NMR ~ 7.45-7.3 (m, 5, ArH), 6.4 (br s, 1, NH
of ~-lactam), 5.40 (d, 1, J = 8.6, BocNH), 5.26 (s, 2, ArCH2), 5.06 (br dd, 1, J = 4.5 Hz, 8.5 Hz; C3H), 3.79 (dt, J = 4.5, 8.5 Hz, C4H), 3.05-2.82 (m, 2, CH2CH2CO); ~-2.0-1.73 (m, 2, CH2CH2CO), 1.45 (s, 9, tert-butyl).
Anal. Calcd. for C20H24N406 H, 5.81. Found: C, 57.57; H, 5.74. --~
C. Rhodium (II) CYclization A solution of the diazo ~-keto benzyl ester ;~
(0.12 g, 0.29 mmol) in 6 mL of alumina filtered chloro-20 form was heated to reflux and treated with rhodium (II) ;
acetate dimer (l.S mg, 0.0034 mmol). After heating for ~-~
20 minutes, the title compound was produced.
H NMR (CDC13, 300 MHz) S 11.3 (br s, lH, OH), 7.50~
7.30 (m, 5H, ArH), 5.37-5.27 (AB pattern, 2H, ArCH2), 5.20-5.08 ~m, 2H, C7-H and BocNH), 3.83-3.72 (m, lH, C6-H), 2.58-2.45 (m, 2H, C2 methylene protons), 2.12-2.00 (m, lH, one of Cl methylene protons), 1.74-1.58 (m, lH,ione of C1 methylene protons), 1.47 (s, 9H, tert-butyl group).
~ :.

~`` 13320.~9 ~
X-6605 -48a-Example 7 l-Benzvl-~-[4(S~-phenyloxazolidin-2-one-3- - ;
5 yll-4~-hYdroxymethylazetidin-2-one ~

A solution of l-benzyl-3i3-[4(S)-phenyloxa- - ~.
~ zolidin-2-one-3-yl)-4i3-styryl-azetidine-2-one (3.0 g, :~ 7.06 mmol) in 80 mL of 50% methanol in dichloromethane 1 0 "'"
.~:
,:

~ 15~:

1332059 ~'.
X-6605 -49- ~
. ,j",, .

containing two drops of pyridine and a few milligrams of Sudan III dye (Aldrich Chemical Co.) was treated with a dilute mixture of ozone in oxygen at -7~C. ;`-~
When the red color of the dye was consumed, the ozone ~
5 inlet was removed and 8 mL of dimethyl sulfide added. ~ ;
The solution was stirred for 3 hours at room temperature and then concentrated under reduced pressure. The oil ~-~
was redissolved in 3S mL of ethanol, cooled ot 0C, and ;;1 ;
treated with sodium borohydride (0.40 g, 10.6 mmol). `~
After ca. 15 minutes a heavy precipitate formed. Water 3S mL) was added and stirring continued at room tempera- ;~
ture for another 30 minutes. Most of the ethanol was ~ ;
removed under reduced pressure and the remaining slurry partitioned between dichloromethane and water (200 mL
each). The organic layer was dried (Na25O4) and concen-trated to a white solid. Recrystallization from ethyl acetate - dichloromethane (first crop, 1.887 g) and etkyl acetate - hexanes (second crop, 0.501 g) gave ~ -2~.388 g (96%) of 1-benzyl-3~-[4(S)-phenyloxazolidin-2-20 one-3-yl]-4~-hydroxymethyl-azetidine-2-one as white .!
neçdles: mp l59~.5 - 160.0C; [~]D23 +10g.1 (c = 2.2, CHCl3);; IR 3450 (`br), 3010, 1760, }500, 1480, 1460, ~ ;;
1410 cm~l; 1H NMR (~CDCl3) ~ 7.50-7.00 (m, 10, ArH), 5.09 (dd, l, J = 6.5, 9.1 Hz, ArCHCH2), 4.74 (t, l, J = 9.0 Hz, 25 ~one of ArCHCH2),~4.~49, (d, l, J = 4.7 HZ, C-3 H), 4.32-4.26 (m, 3, AB pattern of ArCH2N and one of ArCHCH2), 3.71 (dt, 1, J = 5.0, 7.2 Hz, C 4 H); 3.56-3.34 (m, 2, CH20H),i2.32 (dd, 1, J = 5.1, 6.5 Hz, OH). I ~

:',; ." 'i ' '.

:~ ; ",.;'",''' X-6605 _50- 1332059 Example 8 3~BenzyloxYcarbonYlamino-4~-hydroxymethyl- -azetidin-2-one ~-The ~-hydroxymethylazetidinone (0.497 g, :~
1.41 mmol) was dissolved with warming in 8 ml of 7:1 THF:tert-butanol and added to a -78C solution of lithium (0.087 g, 12.6 mmolj in 23 mL of anhydrous ammonia over 2 minutes. After stirring for an addi-tional 2 minutes the excess lithium was quenched with 2 mL of 50% tert-butanol in benzene. Powdered ammonium ; chloride (0.68 g, 12.7 mmol) was added and the ammonia ~-; was allowed to distill off. Solvent, and any remaining 15~ ammoniaj were then removed under reduced pressure. The ,.-residue~was dissolved in water (15 mL), acidified ~-briefly to pH 3 with lN aqueous NaRS04, and then basi-fied to pH 8 with 3N aqueous NaOH. Benzyl chloroformate (0.42 ml, 3.0 mmol) was added, and the reaction stirred ~at room temperature, using a~ueous sodium hydroxide to malntain the pH at ca 8. After 3 hours excess benzyl chloroformate~was~ destroyed with aqueous ammonia and the ~`~
mixturé;~extracted with dichloromethane (1 X 150 mL, 1 X , ~ -50~mL~ The organic layers were dried (Na2SO4) and ``
25 ~ concentrated. ~Chromatography on 35 g of silica with 12%
isopropanol~in;~dichloromethane afforded 0.219 g (62%) of 3;~-benzyloxycarbonylamino-4~-hydroxymethyl-azetidine-2 one as a'~white solid. Recrystallization from hexanes -e ~ 1 ~acetate gave an analytical sample: mp 12 5 ~
~30~ 129.5~C;~ ~a~]D ~= +7.1 (c - 1.0, CHC13~; IR (CHC13) X-6605 -51- 1 3 3 2 0 ~ 9 .. . .
. ,,;
3400 (v br), 3010, 2g50, 1765, 1720, 1520, 1320, 1230, 1050 cm~l; lH NMR (CDCl3) ~ 7.33 (s, 5, ArH), 6.94 (s, 1, NH of ~-lactam), 6.32 (d, 1, J = lOHz, NH at C-~
5.14 (dd, 1, J = 4.9, 10.0 Hz, C-3 H), 5.07 (s; 2, 5 ArC~2), 3.85-3.55 (m, 4, C-4 H, C~2OH).

Example 9 ~, .:,~
l-~enzyl-3~ olidin-2-one-3-Yl)- ,'.~-10 4~-[2-(2-furYl~ethyllazetidin-2-one ~, :

;~ The product obtained as described by Example 3, (O.S g) was dissolved in 10 ml of methylene chloride and was hydrogenated at room temperature for one hour under -~
15~ 50 psi hydrogen pressure in the presence of 0.05 g of 5% ~`
palladium on carbon. The reduction mixture was filtered and the clear filtrate was evaporated to provide the title compound as a white solid.
~ ~.....
ExamPle 10 3~-t-ButYloxvcarbonYlamino-4~-~2-(2-furYl)- ;;H~
ethyllazetidin-2-one A S00 ml 5-necked flask equipped with a ~;-nitrogen inlet, ammonia inlet, stirrer, thermometer, and drying tube was cooled under nitrogen to a temperature of abouti -70C. in an acetone-dry ice bath. The ammonia was turned on, the nitrogen flow discontinued, and about 200 ml of ammonia were collected in the flask. Lithium "~

- .~.......

~ - , ,:" ~
-.~

~332059 (1.66 g, 240 mmole) cut in small pieces from lithium wire and washed under argon with benzene and diethyl ether was added to the ammonia.
To the blue lithium-ammonia solution was added dropwise over 4.5 minutes a solution of 10 g (24 mmole) of 1-benzyl-3~-[4(S)-phenyloxazolidin-2-one-3-yl]-4~-[2-(2-furyl)ethyl]-azetidin-2-one in 80 ml of tetra-hydrofuran containing 3.85 ml (72 mmole) of t-butyl alcohol. The temperature of the reaction mixture rose to -46C. and ~he mixture was stirred for about 3 minutes. The reaction was quenched with 18.9 ml of 1,2-dichloroethane and 3.14 ml of acetic acid. The ammonia was evaporated by warming the mixture to room `
temperature and the T~F was distilled off. THF was again added and distilled off to remove all ammonia.
Aqueous THF was added to the residue of the product fol-lowed by 11.58 ml (48 mmole) of di-t-butyl dicarbonate `~
and the mixture was stirred overnight at room tempera ture.
The two-phase reaction mixture was extracted -with methylene chloride and the extract dried and evapo-rated to dryness. The residue was stirred with diethyl ether a~d the white solid filtered to yield 1.7 g of the product, 3~-t-butyloxycarbonylamino-4~-[2-(2-furyl)ethyl]~
azetidin-2-one as a white solid. An additional 900 mg of the product was obtained from the mother liquor by -~
trituration with ether.
, .'~;'', ' ' '''',''''''' "`.'"
, ~ ,:"~

. -.:; ,: :, :,. "

:'' '.~:', "'~

X-6605 _53_ 1 3 3 2 0 5 9 :

ExamPle 11 l-t-ButYloxYcarbonYlmeth~1-3~-t-~utYloxycar-bonylamlno-4~-l2-(2-furyl)ethYl~azetidin-2-one To a cold (-30C.) solution of 1.2 g (4.3 mmole) of 3~-t-butyloxycarbonylamino-4~-[2-(2-furyl)-ethyl]azetidin-2~one in 15 ml of DMF were added dropwise with stirring 1.94 ml of "Triton B"*. T~e mixture was ~;
stirred for 15 minutes at -30C., warmed to 0C. ~or 15 ~ -minutes, and recooled to -30C. A solution of t-butyl bromoacetate in 3 ml of DMF was added dropwise and the mixture stirred at -30C. for 15 minutes, 1 hour at 0C.
and at room temperature for 2 hours. Cold water was added to the mixture and the precipitate was filtered.
The precipitate was washed with water to remove DMF and dried under vacuum to yield 1.2 g (71% yield) of the title compound as a white solid.

Example 12 l-t-~3utyloxycarbony~-3~-t-butYloxycar bonylamino-4~-(2-carboxYethYl)azetidin-2-one -A 100 ml round bottom flask e~uipped with a ~ -magnetic stirrer, nitrogen inlet, ozone inlet, a sodium bisulfite scrubber, and a thermometer, was charged with -; ~;! "
a solution of 1.0 g of 1-t-butyloxycarbonylmethyl-3~-t-butyloxycarbonyl-amino-4~-[2-(2-furyl)ethyl]azetidin-2-one in 30 ml of methylene chloride:methyl alcohol 1 , * Trade mark for tetramethylammonium hydroxide. ~ ~
'' ' ":'' " ' .:: ' , ' . . .. ' .. . .. .

X-6605 _54_ 13320~9 v:v, and cooled to -78C. A few crystals of Sudan III
red dye were added and a stream of ozone in air was bubbled through the solution until the red color was discharged (ca. 40 minutes)~ The cooling bath was S removed and 1.56 ml of dimethylsulfide were added.
The reaction mixture was warmed to room teperature and ;~
stirred for about 5 hours. The mixture was poured into aqueous sodium bicarbonate and the mixture washed with methylene chloride. The aqueous lay~r was acidified with hydrochloric acid and extracted with methylene chloride. The extract was washed with brine, dried over - -~
sodium sulfate and evaporated to yield 400 mg of the title compound as a foam.
Example 13 ~ -l-t-ButYloxYcarbonvlmethyl-3~-t-butvloxycar- ,.
bonylamino-4~-(2-PhenYlthiocarbonylethyl)azetidin-2-one ;~
.~ , ... . .
,, .y;;
To a cold (0C.) solution of 350 mg of l-t-butyloxycarbonylmethyl-3~-t-butyloxycarbonylamino-4 (2-carboxyethyl)azetidin-2-one in 6 ml of methylene -chloride containing 1 ml of DMF maintained under nitro-gen were added 26 mg of dimethylaminopyridine, 0.308 ml 25 of thiophenol, and 212 mg of dicyclohexylcarbodiimide ;;;~ ;~
(DCC). The mixture was stirred in the cold for 10 min- ; ~-`
utes and at room temperature for 1 hour. An additional `; -~
45 mg of DCC were added and stirring was con~inued for 2 hours. After standing overnight, the mixture was poured into 40 ml of methylene chloride and the mixture washed ;,,. ~. , ,'`'`'-'' i ~;

' ~ ~'' '''."'''.' '' ~''.'~;''' with an aqueous sodium bicarbonate solution (50% of satu-rated), with 0.lN hydrochloric acid, and with a satuxated sodium bicarbonate solution. The solution was dried over sodium sulfate and evaporated to dryness to yield the title compound as a partly crystalline oil.

ExamPle 14 t~But~l 7~-t-b~tyln~yc~rbo~amino-3-hYdroxY-1-carba(l-dethia)-3-ceDhem-4-carboxYlate To a solution of 4.4 g (9.47 mmole) of the azetidinone ~henylthio ester, prepared according to the method described in Example 14 in lO0 ml of dry THF and maintained under argon at -78C is added 29.5 ml (3.12 mmol) of lithium hexamethyldisilazane. After about 15 minutes the mixture is poured into 750 ml of agueous ammonium chloride (50% of saturation) and the pH is adjusted to 3 with lN hydrochloric acid. The acidified mixture is extracted three times with 50 ml portions of methylene chloride, the extracts combined, washed with brine, dried over sodium sulfate and concentrated ;;
by evaporation. The concentrate is initially chro-matographed over silica using hexane-ethyl acetate, ca 3:1, v:v followed by a 1:1, v:v. mixture of the same solvents for elution of the product. The eluate is evaporated to dryness to provide the title compound.

Claims (2)

1. A process for preparing a compound of Formula (I):

(I) wherein Ar is phenyl, C1-C4 alkylphenyl, halophenyl, C1-C4 alkoxyphenyl, naphthyl, thienyl, furyl, benzo-thienyl, or benzofuryl; R is phenyl, C1-C4 alkylphenyl, C1-C4 alkoxyphenyl, or halophenyl; Y is -CH=CH-, or -CH2-CH2-; and R' is phenyl, C1-C4 alkylphenyl, C1-C4 alkoxyphenyl, halophenyl, furyl or naphthyl, which com-prises reacting a compound of Formula (5a):

(5a) with a compound of Formula (6a):

(6a) wherein X' is chloro, bromo, trifluoroacetoxy, or -OP(=O)X2, wherein X is halogen, so as to produce a compound of formula (I) where Y is -CH=CH-, optionally followed by hydrogenation to produce a compound of formula (I) where Y is -CH2-CH2-.

2. A compound of Formula (I):

(I) wherein Ar is phenyl, C1-C4 alkylphenyl, halophenyl, C1-C4 alkoxyphenyl, naphthyl, thienyl, furyl, benzo-thienyl, or benzofuryl; R is phenyl, C1-C4 alkylphenyl, C1-C4 alkoxyphenyl, or halophenyl; Y is -CH=CH-, or -CH2-CH2-; and R' is phenyl, C1-C4 alkylphenyl, C1-C4 alkoxyphenyl, halophenyl, furyl or naphthyl.