2-Azetidinone 4-carboxy derivatives and a process for producing the same

A 2-azetidinone of formula (I): ##STR1## wherein R.sub.1 represents an aralkoxy, acyloxy, sulphonyloxy or amino group any of which may be substituted, or hydrogen, hydroxy, alkoxy or azido; PA0 R.sub.2 represents an alkyl or aralkyl group either of which may be substituted, or hydrogen; PA0 R.sub.3 represents an alkyl, aryl, aralkyl, alkenyl, aralkenyl, alkynyl, aralkynyl, acyl or heterocyclic group any of groups may be substituted; and PA0 R.sub.4 represents an alkyl, alkenyl, aryl or aralkyl group any of which may be substituted; or formula (I'): ##STR2## wherein R.sub.1 ' is the same as R.sub.1 above; PA0 R.sub.2 ' represents an alkyl, aralkyl or trialkylsilyl group any of which may be substituted, or hydrogen; PA0 R.sub.3 ' is the same as R.sub.3 above; and PA0 R.sub.4 ' represents an alkyl, aralkyl or trialkylsilyl group any of which may be substituted, or hydrogen; provided that when R.sub.1 ' represents azido or optionally substituted amino, R.sub.2 ' represents hydrogen or CH.sub.2 CCl.sub.3 and R.sub.4 ' represents ##STR3## R.sub.3 ' represents other than ##STR4## or a pharmaceutically acceptable salt thereof is disclosed. The derivatives exhibit .beta.-lactamase inhibiting activity and are thus of interest as anti-bacterial agents, used alone or together with known antibiotic subtances.

SUMMARY OF THE INVENTION 
This invention relates to 2-azetidinone derivatives. 
In general terms, the present invention provides a 2-azetidinone derivative 
corresponding to the following general formula (I): 
##STR5## 
wherein R.sub.1 represents an aralkoxy (e.g. benzyloxy), acyloxy (e.g. 
carbobenzoxy or acetyloxy), sulphonyloxy (e.g. p-toluene-sulphonyloxy or 
methanesulphonyloxy) or amino (e.g. dialkylamino, phthalylimino, 
alkylidene-amino, carbobenzoxyamino or benzylamino) group any of which may 
be substituted one or more times (e.g. by halogen, lower alkyl, lower 
alkoxy or nitro) or hydrogen, hydroxy, alkoxy (e.g. tetrahydropyranyloxy 
or t-butoxy) or azido; 
R.sub.2 represents an alkyl (e.g. methyl, ethyl, i-propyl or n-, i- or 
t-butyl) or aralkyl (e.g. benzyl, diphenylmethyl, trityl or phthalidye) 
group either of which groups may be substituted one or more times (e.g. by 
halogen, lower alkyl, lower alkoxy or nitro) or hydrogen; 
R.sub.3 represents an alkyl (e.g. methyl, ethyl, n-, or i-butyl or pentyl) 
aryl (e.g. phenyl or naphthyl), aralkyl (e.g. benzyl), alkenyl (e.g. 
ethenyl, 1- or 2-propyl or 3-butenyl), aralkenyl (e.g. styryl or 
cinnamyl), alkynyl (e.g. ethynyl, 1- or 2-propynyl or 1- or 2-butynyl), 
aralkynyl (e.g. 2-phenyl-1-ethynyl), acyl (e.g. acetyl, propionyl or 
butyryl), or heterocyclic group (e.g. 2- or 3-furyl, 2- or 3-thienyl, 2- 
or 3-pyrrolyl, 2- or 4-imidazolyl, 3-pyrazolyl, 4-isoxazolyl, 2-, 3-, 4-, 
5-, 6- or 7-indolyl or 2- or 3-benzo (b) furanyl), any of which groups may 
be substituted one or more times (e.g. by halogen, lower alkyl, lower 
alkoxy, lower acyloxy, hydroxy, optionally substituted amino, optionally 
substituted thio or nitro); 
R.sub.4 represents an alkyl (e.g. methyl, ethyl, i-propyl, pentyl or n-, i- 
or t-butyl), alkenyl (e.g. ethenyl, 1- or 2-propenyl or 3-butenyl), aryl 
(e.g. phenyl or naphthyl) or aralkyl (e.g. benzyl, diphenylmethyl, trityl 
or phthalidyl) group any of which groups may be substituted one or more 
times (e.g. by halogen, lower alkyl, lower alkoxy, lower acyloxy, hydroxy, 
optionally substituted amino, optionally substituted thio or nitro); or 
corresponding to the following general formula (I'): 
##STR6## 
wherein R.sub.1 ' represents an aralkoxy (e.g. benzyloxy), acyloxy (e.g. 
carbobenzoxy or acetyloxy), sulphonyloxy (e.g. p-toluene-sulphonyloxy or 
methanesulphonyloxy) or amino (e.g. dialkylamino, phthalylimino, 
alkylidene-amino, carbobenzoxyamino or benzylamino) group any of which may 
be substituted one or more times (e.g. by halogen, lower alkyl, lower 
alkoxy or nitro) or hydrogen, hydroxy, alkoxy (e.g. tetrahydropyranyloxy 
or t-butoxy) or azido; 
R.sub.2 ' represents an alkyl (e.g. methyl, ethyl, i-propyl or n-, i- or 
t-butyl), aralkyl (e.g. benzyl, diphenylmethyl, trityl or phthalidyl) or 
trialkylsilyl group any of which groups may be substituted one or more 
times (e.g. by halogen, lower alkyl, lower alkoxy or nitro) or hydrogen; 
R.sub.3 ' represents an alkyl (e.g. methyl, ethyl, n- or i-butyl or 
pentyl), aryl (e.g. phenyl or naphthyl), aralkyl (e.g. benzyl), alkenyl 
(e.g. ethenyl, 1- or 2-propenyl or 3-butenyl), aralkenyl (e.g. styryl or 
cinnamyl), alkynyl (e.g. ethynyl, 1- or 2-propynyl or 1- or 2-butynyl), 
aralkynyl (e.g. 2-phenyl-1-ethynyl), acyl (e.g. acetyl, propionyl or 
butyryl) or heterocyclic group (e.g. 2- or 3-furyl, 2- or 3-thienyl, 2- or 
3-pyrrolyl, 2- or 4-imidazolyl, 3-pyrazolyl, 4-isoxazolyl, 2-, 3-, 4-, 5-, 
6- or 7-indolyl or 2- or 3-benzo (b) furanyl) any of which group may be 
substituted one or more times (e.g. by halogen, lower alkyl, lower alkoxy, 
lower acyloxy, hydroxy, optionally substituted amino, optionally 
substituted thio or nitro); 
and 
R.sub.4 ' represents an alkyl, (e.g. methyl, ethyl i-propyl or n-, i- or 
t-butyl), aralkyl (e.g. benzyl, diphenylmethyl, trityl or phthalidyl) or 
trialkylsilyl group any of which groups may be substituted one or more 
times (e.g. by halogen, lower alkyl, lower alkoxy or nitro) or hydrogen; 
or a pharmaceutically acceptable salt thereof. 
Also, in general terms, the present invention provides an optically active 
form of such a derivative corresponding to the following general formula 
(Ia): 
##STR7## 
wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are as defined above; or 
corresponding to the following general formula (I'a): 
##STR8## 
wherein R.sub.1 ', R.sub.2 ', R.sub.3 ' and R.sub.4 ' are as defined 
above; or a pharmaceutically acceptable salt thereof. 
In a first embodiment, the present invention provides a 2-azetidinone 
derivative corresponding to the following general formula (II): 
##STR9## 
wherein R.sub.1 represents an aralkoxy, acyloxy, sulphonyloxy or amino 
group any of which groups may be substituted one or more times or 
hydrogen, hydroxy, alkoxy or azido; 
R.sub.2 represents an alkyl or aralkyl group either of which groups may be 
substituted one or more times; 
R.sub.3 represents an alkyl, aryl, aralkyl, alkenyl, aralkenyl, alkynyl, 
aralkynyl or acyl group any of which groups may be substituted one or more 
times; 
and 
R.sub.4 represents an alkyl, alkenyl, aryl, or aralkyl group any of which 
groups may be substituted one or more times. 
This embodiment of the present invention also provides an optically active 
form of such a derivative corresponding to the following general formula 
(IIa): 
##STR10## 
wherein R.sub.2, R.sub.3 and R.sub.4 are as defined above. 
In a second embodiment, the present invention provides a 2-azetidinone 
derivative corresponding to the following general formula (III): 
##STR11## 
wherein R.sub.1 represents an aralkoxy, acyloxy, sulphenyloxy or amino 
group any of which groups may be substituted one or more times or 
hydrogen, hydroxy, alkoxy or azido; 
R.sub.2 represents an alkyl or aralkyl group either of which groups may be 
substituted one or more times; 
R.sub.3 represents an alkyl, aryl, aralkyl, alkenyl, aralkenyl, alkynyl, 
aralkynyl, acyl or heterocyclic group any of which groups may be 
substituted one or more times; 
and 
R.sub.4 represents an alkyl, alkenyl, aryl or aralkyl group any of which 
groups may be substituted one or more times. 
This embodiment of the present invention also provides an optically active 
form of such a derivative corresponding to the following general formula 
(IIIa): 
##STR12## 
wherein R.sub.2, R.sub.3 and R.sub.4 are as defined above. 
In a third embodiment, the present invention provides a 2-azetidinone 
derivative corresponding to the following general formula (IV): 
##STR13## 
wherein R.sub.1 ' represents an aralkoxy, acyloxy or sulphonyloxy group 
any of which groups may be substituted one or more times or hydrogen, 
alkoxy, azido or disubstituted amino; 
R.sub.2 ' represents an alkyl, aralkyl or trialkylsilyl group any of which 
groups may be substituted one or more times or hydrogen; 
R.sub.3 ' represents an alkyl, aryl, aralkyl, alkenyl, aralkenyl, alkynyl, 
aralkynyl, acyl or heterocyclic group any of which groups may be 
substituted one or more times; 
and 
R.sub.4 ' represents an alkyl, aralkyl or trialkylsilyl group any of which 
groups may be substituted one or more times or hydrogen; 
or a pharmaceutically acceptable salt thereof. 
This embodiment of the present invention also provides an optionally active 
form of such a derivative corresponding to the following general formula 
(IVa): 
##STR14## 
wherein R.sub.1 ', R.sub.2 ', R.sub.3 ' and R.sub.4 ' are as defined 
above; or a pharmaceutically acceptable salt thereof. 
Regarding the compounds corresponding to above general formulae (I), (Ia), 
(II), (IIa), (III) and (IIIa), when R.sub.3 represents an acyl group 
corresponding to the following general formula: 
##STR15## 
wherein R.sub.5 represents C.sub.2 -C.sub.5 alkyl; at least part of these 
compounds is present in the following end form conjugated with a secondary 
amide: 
##STR16## 
Preferred examples of pharmaceutically acceptable salts of the above 
compounds include metallic salts obtained using, as at least one member of 
R.sub.2, R.sub.2 ', R.sub.4 or R.sub.4 ', an alkali metal (e.g. sodium or 
potassium) or an alkaline earth metal (e.g. calcium or magnesium) and 
salts obtained using an organic base (e.g. triethylamine, 
dicyclohexylamine, morpholine, piperidine or pyridine). 
The derivatives corresponding to the above general formulae exhibit 
.beta.-lactamase inhibiting activity and are thus of interest as 
anti-bacterial agents. For example, they may be used alone or together 
with known antibiotic substances, such as cephalosporins and penicillins, 
for treating various infectious diseases. 
They may also be used as intermediates in the preparation of other similar 
derivatives. 
For example, they may be used in the preparation of bicyclic .beta.-lactam 
antibiotic substances such as O-2-isocephem compounds corresponding to the 
following general formula (reported by T. W. Doyle et al, Can. J. Chem., 
55, 484, (1977)) and analogues thereof: 
##STR17## 
The present invention is based upon the discovery that various antibiotic 
substances of .beta.-lactam type and skeletal analogues thereof possess 
commonly a certain absolute configuration at the 4th position of the 
2-azetidinone which appears to be essential for exhibiting activity 
against bacteria and .beta.-lactamase. 
.beta.-lactamase inhibiting activities of some compounds according to the 
present invention were determined by using .beta.-lactamase produced by 
Enterobacter sp. KY 3073 and chromogenic cephalosporin as substrate in a 
similar manner to that described in Antimicrobial Agent and Chemotherapy, 
Vol. 1, 283, (1972) to give the following results: 
______________________________________ 
Inhibition 
Concentration activity 
Compound of (.mu.g/ml) % 
______________________________________ 
Example 6 50 50 
7 100 50 
9 50 18 
11 50 15 
12 50 22 
14 50 20 
15 50 34 
______________________________________ 
In one embodiment, the present invention further provides a process for the 
preparation of a derivative corresponding to above general formulae (I), 
(Ia), (II), (IIa), (III) and (IIIa) which comprises condensing, in a 
solvent, an aspartic acid derivative corresponding to the following 
general formula: 
##STR18## 
an aldehyde corresponding to the following general formula: 
EQU R.sub.3 CHO 
and an isonitrile corresponding to the following general formula: 
EQU R.sub.4 N.tbd.C 
wherein 
R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are as defined above. 
In another embodiment, the present invention further provides a process for 
the preparation of a derivative corresponding to above general formulae 
(I'), (I'a), (IV) and (IVa) which comprises reacting a 2-azetidinone 
derivative corresponding to the following general formula: 
##STR19## 
wherein R.sub.1 ', R.sub.2 ' and R.sub.3 ' are as defined above; 
and 
R.sub.6 represents an alkyl, alkenyl, aryl or aralkyl group any of which 
groups may be substituted one or more times; 
with a halogenating agent to give an imidoylhalide, reacting the 
imidoylhalide with an appropriate alcohol or alkoxide to give an 
iminoether derivative and hydrolysing the iminoether derivative. 
The present invention also relates to the thus prepared derivatives and to 
pharmaceutical compositions comprising such derivatives and 
pharmaceutically acceptable carriers or diluents and optionally 
penicillins or cephalosporins. The present invention further relates to 
the use of such derivatives or such compositions for inhibiting 
.beta.-lactamase activity. 
In more general terms now, the derivatives corresponding to the following 
general formula: 
##STR20## 
wherein R.sub.7 represents hydrogen, hydroxy, alkoxy, optionally 
substituted aralkyloxy, optionally substituted acyloxy, optionally 
substituted sulphonyloxy, optionally substituted amino or azido; 
R.sub.8 and R.sub.10, which may be the same or different, each represents 
hydrogen, optionally substituted alkyl or optionally substituted aralkyl; 
and 
R.sub.9 represents an alkyl, aryl, aralkyl, alkenyl, aralkenyl, alkynyl, 
aralkynyl, heterocyclic or acyl group, each of which may optionally be 
substituted; 
or optionally active derivatives corresponding to the following general 
formula: 
##STR21## 
wherein R.sub.7, R.sub.8, R.sub.9 and R.sub.10 are as defined above; may 
be prepared by treating a 2-azetidinone derivative corresponding to one of 
the following general formulae: 
##STR22## 
wherein R.sub.7 ' represents hydrogen, alkoxy, optionally substituted 
aralkyloxy, optionally substituted acyloxy, optionally substituted 
sulphonyloxy, di-substituted amino or azido; 
R.sub.8 ' represents an optionally substituted alkyl or optionally 
substituted aralkyl group; 
R.sub.9 is as defined above; 
and 
R.sub.11 represents an alkyl, alkenyl, aryl or aralkyl group, each of which 
may optionally be substituted; 
[however, when R.sub.9 represents an acyl group in enol form, the enol of 
R.sub.9 may be protected by an acyl group (e.g. enol acetate) or alkyl 
group (e.g. enol methyl ester)]; with a halogenating agent to form a 
corresponding imidoylhalide derivative, treating the imidoylhalide 
derivative with an alcohol or alkoxide to form an iminoether derivative, 
subjecting the same to the hydrolysis and, if desired, removing the 
protective group from the carboxyl, amino or hydroxy group in conventional 
manner. 
The derivatives corresponding to the above general formulae (C) and (D) may 
be prepared by carrying out, in a suitable solvent a condensation reaction 
of an aspartic acid derivative corresponding to the following general 
formula: 
##STR23## 
wherein R.sub.12 represents hydrogen, hydroxy, alkoxy, optionally 
substituted aralkyloxy, optionally substituted sulphonyloxy, substituted 
amino or azido; and 
R.sub.8 ' is as defined above; with an aldehyde corresponding to the 
following general formula: 
EQU R.sub.9 CHO 
wherein R.sub.9 is as defined above; and an isonitrile corresponding to the 
following general formula: 
EQU R.sub.11 N.tbd.C 
wherein R.sub.11 is as defined above; and, if desired, removing the 
protective group from the carboxylic group or amino group. 
By the process according to the present invention, a secondary amide 
derivative is converted into an iminoether-type compound which is then 
converted into an ester-type compound. The application of such a method to 
the preparation of 2-azetidinone derivatives is now proposed for the first 
time although this method is known in connection with other compounds. For 
example, analogous methods have been applied to the amidolysis of acylated 
7-aminocephalosporanic acid derivatives, but such methods were not 
directed to the production of esters, but to the production of amino 
compounds. In other words, such methods were used to obtain an amino group 
attached to the 3rd position of a 2-azetidinone moiety, as reported, for 
example, in Helv. Chim. Acta., 51, p. 1108 (1968); J. Org. Chem. 36, p. 
1259 (1971); J. Antibiotics, 25, p. 248 (1972); and published Japanese 
Patent Application Nos. 23090/77 and 31095/77. 
Reference may also be made in this connection to German Auslegeschrift No. 
1,160,444. 
Alternatively, the derivatives corresponding to above-defined general 
formulae (A) or (B) may be prepared by converting an ester group of a 
derivative corresponding to one of the following general formulae: 
##STR24## 
wherein R.sub.7 ', R.sub.8 ' and R.sub.9 are as defined above; 
and 
R.sub.13 represents alkyl or aralkyl; 
selectively into the corresponding carboxyl group. In this case, it is 
possible to select, depending upon the types of the groups R.sub.8 ' and 
R.sub.13 ', various techniques of the known types, for example, the 
reaction conditions (e.g. the intensity of the reagents (acid and base), 
reaction temperature and time and agents used for hydrolysis, reduction, 
hydrogenation or dealkylation). 
In a preferred embodiment of the present process, the hydrogenation of a 
compound corresponding to general formulae (E) or (F) (wherein R.sub.8 ' 
represents benzyl and R.sub.13 represents methyl) may be effected by using 
a palladium-carbon catalyst so that the hydrogenolysis of the group 
--COOR.sub.8 ' is selectively effected to form a compound (A) or (B) 
(wherein R.sub.8 represents hydrogen R.sub.10 represents methyl) as 
monocarboxylic acid. On the other hand, when a compound (E) or (F) 
(wherein R.sub.8 ' represents t-butyl and R.sub.13 represents methyl) is 
used for the reaction, the group --COOR.sub.13 is selectively hydrolized 
in the presence of a potassium carbonate catalyst to form a compound (A) 
or (B) (wherein R.sub.8 represents t-butyl and R.sub.10 represents 
hydrogen) as monocarboxylic acid. 
When a compound (A) or (B) wherein either of R.sub.8 or R.sub.10 represents 
hydrogen is prepared, it is advantageous to use as a starting material a 
compound wherein one of R.sub.8 or R.sub.10 may more readily be converted 
into a carboxylic acid than the other. 
It is particularly advantageous to select R.sub.8 so that the group may be 
converted to a carboxylic acid group without undesirable side-effects upon 
other parts of the molecule, because those compounds wherein only the 
R.sub.8 group has been converted to a carboxylic acid group are 
particularly useful as intermediates. 
The derivatives (A) may be prepared by treating a compound (C) with a 
halogenating agent to form a corresponding iminohalide, treating the 
iminohalide with an alcohol or alkoxide of an alkali metal to form an 
iminoether and subjecting the same to the hydrolysis. In this process, the 
reaction proceeds as follows. 
##STR25## 
In this process, it is possible, if desired, to remove the protective group 
from a carboxyl, amino or hydroxy group in conventional manner, as shown 
by the line marked**. 
The above-mentioned reaction may proceed continuously in a same solvent and 
thus the intermediates are usually not isolated. Examples of the inert 
solvents which may be used include: chloroform, dichloromethane, 
dichloroethane, benzene, diethyl ether, tetrahydrofuran and dioxane. The 
starting materials are usually used in an amount of from 1 millimole to 2 
mole preferably from 10 millimole to 0.5 mole, per liter of solvent. 
Examples of the halogenating agents which may be used include: phosphorus 
pentachloride, phosphorus oxychloride, thionyl chloride, phosgene, 
oxalylchloride and a complex of dichlorophenylphosphine and chlorine; it 
is preferred to use phosphorus pentachloride. 
The amount of halogenating agent used is generally from 1 to 10 mole, 
preferably from 1 to 2 mole, per mole of compound. Depending upon the type 
of starting materials used and other conditions, the reaction temperature 
and time may vary from -78.degree. to +150.degree. C., preferably from 
-10.degree. to +50.degree. C., for a period of from 10 minutes to 24 
hours. In the reaction, it is possible to use as a catalyst a base, such 
as a tertiary amine, e.g. triethylamine, pyridine, quinoline or 
dimethylaniline. Generally, the amount of base used may vary, depending 
upon the amount of the halogenating agent used and other conditions, from 
1 to 50 mole, preferably from 1 to 20 mole, per mole of the starting 
materials. 
Examples of the alcohols and alkoxides which may be used include: lower 
alkyl alcohols, e.g. methanol or isobutanol and lower haloalkyl alcohols 
and alkoxides obtained using such alcohols and alkali metals. Usually, an 
excess of alcohol is used, e.g. from 20 to 1000 mole per mole of the 
starting materials, while the amount of alkoxide used may vary, depending 
upon the amount of halogenating agent used in the foregoing steps, 
preferably from 2 to 50 mole. 
The reaction temperature and time may vary, depending, for example, upon 
the type of halogenating agent, base, alcohol or alkoxide used, from 
-78.degree. to +150.degree. C., preferably from -40.degree. to +50.degree. 
C., for a period of from 10 minutes to 48 hours. 
The ester (E) is obtained by treating the produced iminoether with an 
acidic aqueous solution, water or an alkaline aqueous solution, depending, 
for example, upon R.sub.11 and the reaction conditions in the foregoing 
steps. An especially good result may be obtained by using an aqueous 
solution of HCl (from 0.1 to 1.0 N) and in this case the reaction is 
preferably effected at from -10.degree. to +50.degree. C. for from 5 
minutes to 12 hours.

PREFERRED EMBODIMENTS 
The following non-limitative examples illustrate the invention. 
(Unless otherwise indicated, all products are white to light yellow in 
colour.) 
EXAMPLE 1 
Preparation of 
(4S)-t-butyl-.alpha.-(4-benzyloxycarbonyl-2-oxo-azetidine-1-yl)-.alpha.-(a 
cetyl) acetamide, i.e. 
##STR26## 
L-aspartic acid-.alpha.-benzyl ester (634 mg, 2.84 millimole) suspended in 
methanol (10 ml) was added to 40% aqueous pyruvaldehyde (0.28 ml 1.5 
millimole) and t-butylisonitrile (250 mg, 3.0 millimole) and was stirred 
under nitrogen at room temperature for 48 hours. After completion of the 
reaction, the solution was filtered to remove insoluble materials and the 
filtrate was distilled under reduced pressure to remove the solvent. The 
thus-obtained oily substance was then transferred to a column (diameter 
about 2 cm) packed with 30 g of silica gel (Q23 obtainable from Wako 
Junyaku K.K. Japan) and was purified by column-chromatography using a 
solvent system of hexane/ethyl acetate (1:1 by volume). The eluate was 
divided into 8 ml fractions. Fractions 9 to 30 were collected and 
combined. The solvent was removed from the combined fractions by 
distillation under reduced pressure to yield an oily substance (515 mg) 
having the following physical characteristics. 
______________________________________ 
Elemental analysis as C.sub.19 H.sub.24 N.sub.2 O.sub.5 (molecular 
weight 
360.40): 
C H N 
______________________________________ 
Calculated: (%) 63.32 6.71 7.77 
Observed: (%) 63.41 7.02 7.73 
Specific rotation: [.alpha.].sub.D.sup.23 = -66.9 (CHCl.sub.3, C = 1.63) 
Infra-red absorption spectrum: .gamma..sup.CHCl.sbsp.3 .sub.max(cm.sup.-1) 
1780, 1745, 1680, 1625 
N.M.R. spectrum: .delta.CDCl.sub.3 
1.33; 1.37 (2S 9H) 1.87 (brs 1.88H) 
2.03 (brs 0.3H) 2.30 (brs 0.82H) 2.63- 
3.53 (m 2H) 4.1-4.73 (m 1H) 4.92 (brs 
0.1H) 5.23 (brs 2H) 7.33 (brs 1H) 15.13 
(brs 0.9H) 
Thin layer chromatography: 
Using a silica gel plate (Merck) and 
benzene/acetone (1:1 by volume), a single spot 
was observed (Rf = 0.70). 
______________________________________ 
From these data, the oily substance obtained was identified as 
(4S)-t-butyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(ac 
etyl) acetamide [yield: 50.3%]. When subjected to the FeCl.sub.3 colour 
reaction on the thin layer chromatography plate, this substance becomes 
brown. Also the N.M.R. spectrum reveals a signal of a proton at 
.delta.15.13 which is exchangeable with deuterated methanol. 
These facts indicate the presence of this substance mainly in enol form. 
EXAMPLE 2 
Preparation of 
(4S)-t-butyl-.alpha.-(4-methoxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(styr 
yl) acetamide, i.e. 
##STR27## 
L-aspartic acid-.alpha.-methyl ester (405 mg 2.76 millimole) suspended in 
methanol (8 ml) was added to cinnamaldehyde (0.38 ml, 3.0 millimole) and 
t-butylisonitrile (250 mg 3.0 millimole) and was stirred under nitrogen at 
room temperature for 48 hours. After completion of the reaction, the 
solvent was evaporated off under reduced pressure and the residue was 
washed using a solvent of ethyl acetate and hexane (20 ml; 2:1, by 
volume). The resulting solution was concentrated under reduced pressure 
and was then transferred to a column (diameter about 2 cm) packed with 60 
g of silica gel (Q23). The purification was effected by column 
chromatography using a solvent system of ethyl acetate hexane (1:1 by 
volume) and the eluate was divided into 3 ml fractions. Fractions 28 to 
120 were collected and combined. The combined fractions were distilled 
under reduced pressure to remove the solvent giving a white powder (90 mg) 
having the following physical characteristics. 
______________________________________ 
Elemental analysis as C.sub.19 H.sub.24 N.sub.2 O.sub.4 (molecular 
weight 
344.40): 
C H N 
______________________________________ 
Calculated (%): 
66.26 7.02 8.13 
Observed (%): 
66.16 7.06 7.95 
Specific rotation: [.alpha.].sub.D.sup.23 = -60.0 (CHCl.sub.3, C = 0.02) 
Infra-red absorption spectrum: .gamma..sup.CHCl.sbsp.3 .sub.max(cm.sup.-1) 
1760 (br), 1680 
N.M.R. spectrum: .delta.CD.sub.3 OD 
Note:- ( ) indicates the coupling 
constant (Hz) 1.33 (brs 9H) 2.94-3.39 
(m 2H) 3.63 (S 1.14H) 3.79 (S 1.86H) 
4.43 (m 1H) 4.88 [d 1H(6)] 6.24 [dd 1H 
(6, 16)] 6.74 [dd 1H (2, 16)] 7.33 
(brs 5H) 
Thin layer chromatography: 
Using a silica gel plate (Merck) and 
benzene/ethyl acetate (1:1 by volume) single spot 
was observed (Rf = 0.50). 
______________________________________ 
From these data, the thus-obtained white powder was identified as 
(4S)-t-butyl-.alpha.-(4-methoxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(styr 
yl) acetamide [yield: 9.5%]. 
EXAMPLE 3 
Preparation of 
(4S)-t-butyl-.alpha.-(4-methoxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(isop 
ropyl) acetamide i.e. 
##STR28## 
L-aspartic acid-.alpha.-methylester (405 mg 2.76 millimole) suspended in 
methanol (8 ml) was added to isobutylaldehyde (216 mg 3.0 millimole) and 
t-butylisonitrile (250 mg 3.0 millimole) and was stirred under nitrogen at 
room temperature for 16 hours. After this, the solvent was removed by 
distillation under reduced pressure to give an oily substance which was 
transferred to a column (diameter about 2 cm) packed with 60 g of silica 
gel (Q23). The purification was effected by column chromatography: 200 ml 
of a solvent system of hexane and ethyl acetate (1:1 by volume) is passed 
through the column and then elution is effected using a solvent of 
hexane/ethyl acetate (1:2 by volume). The effluent is divided into 8 ml 
fractions and fractions 35 to 65 are collected and combined. The solvent 
is evaporated off under reduced pressure to give a colourless oily 
substance (520 mg) having the following physical characteristics. 
______________________________________ 
Elemental analysis as C.sub.14 H.sub.24 N.sub.2 O.sub.4 (molecular 
weight 
284.35): 
C H N 
______________________________________ 
Calculated (%): 
59.14 8.51 9.85 
Observed (%): 
59.10 8.58 9.67 
Specific rotation: [.alpha.].sub.D.sup.23 = -69.1 (CHCl.sub.3, C = 1.37) 
Infra-red absorption spectrum: .gamma..sup.CHCl.sbsp.3 .sub.max(cm.sup.-1) 
1755 (br), 1680 
N.M.R. spectrum: in CDCl.sub.3 
as shown in Figure 1 
Thin layer chromatography: 
Using a silica gel plate (Merck) and 
benzene/ethyl acetate (1:1, by volume), a single 
spot was observed (Rf = 0.44). 
______________________________________ 
From these data, the oily substance obtained was identified as 
(4S)-t-butyl-.alpha.-(4-methoxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(isop 
ropyl) acetamide [yield 66.2%]. 
EXAMPLE 4 
Preparation of 
(4S)-t-butyl-.alpha.-(4-benzyloxycarbonyl-2-oxo-azetidine-1-yl)-.alpha.-(p 
henyl) acetamide i.e. 
##STR29## 
L-aspartic acid-.alpha.-benzyl ester (634 mg, 3 millimole) was suspended in 
methanol (10 ml). The suspension was then added to benzaldehyde (318 mg, 3 
millimole) and t-butyl-isonitrile (250 mg, 3 millimole). The mixture was 
stirred under nitrogen at room temperature for 17 hours. After completion 
of the reaction, the solvent was evaporated off and the residue was washed 
using a solvent mixture (20 ml) of ethyl acetate/petroleum ether (20 ml, 
1:10, by volume). The washing solution was concentrated under reduced 
pressure and was then purified by column chromatography using Q23 silica 
gel (60 g). A solvent system of benzene/ethyl acetate (3:1, by volume) was 
used and the eluate was divided into 3 ml fractions. Fractions 28 to 60 
were collected and combined and the solvent was removed by distillation 
under reduced pressure to give an oily substance (380 mg) having the 
following physical characteristics. 
______________________________________ 
Elemental analysis as C.sub.23 H.sub.26 N.sub.2 O.sub.4 (molecular 
weight 
394.45): 
C H N 
______________________________________ 
Calculated (%): 70.63 6.64 7.10 
Observed (%): 70.51 6.56 7.11 
Specific rotation: [.alpha.].sub.D.sup.23 = -65.4 (CHCl.sub.3, C = 0.77) 
Infra-red absorption spectrum: .gamma..sup.CHCl.sbsp.3 .sub.max(cm.sup.-1 
1770, 1740- 60 (sh), 1680 
N.M.R. spectrum: (in CDCl.sub.3) as shown in FIG. 2 
Thin layer chromatography: 
Using a silica gel plate (Merck) and 
benzene/ethyl acetate (1:1, by volume), a single 
spot was observed (Rf = 0.60). 
______________________________________ 
From these data, the oily substance obtained was identified as 
(4S)-t-butyl-.alpha.-(4-benzyloxycarbonyl-2-oxo-azetidine-1-yl)-.alpha.-(p 
henyl) acetamide [yield 32.1%]. 
EXAMPLE 5 
Preparation of 
(4S)-ethyl-.alpha.-(4-methoxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(acetyl 
) acetamide i.e. 
##STR30## 
L-aspartic acid-.alpha.-methyl ester (802 mg, 5.45 millimole) suspended in 
methanol (20 ml) was added to 40% aqueous pyruvaldehyde (0.61 ml, 3.27 
millimole) and ethylisonitrile (300 mg, 5.45 millimole) and was stirred 
under nitrogen at room temperature for 18 hours. After completion of the 
reaction, the solvent was evaporated off. The residue was added to water 
(20 ml) and was extracted using three 20 ml portions of ethyl acetate. The 
extract was washed twice using 10 ml portions of a saturated solution of 
sodium chloride and was dried over Glauber's salt. The solvent was 
distilled off under reduced pressure to give an oily substance which is 
transferred to a column (diameter about 5 cm) packed with 150 g of silica 
gel (Q23). The purification was effected by column chromatography. 
Hexane/ethyl acetate (700 ml, 1:1 by volume) was passed through the column 
and elution was effected using a solvent mixture of hexane/ethyl acetate 
(1:3 by volume). The eluate was divided into 8 ml fractions and fractions 
96 to 145 were collected and combined and the solvent was evaporated off 
under reduced pressure to yield an oily substance (240 mg) having the 
following physical characteristics. 
______________________________________ 
Elemental analysis as C.sub.11 H.sub.16 N.sub.2 O.sub.5 
(molecular weight 256.25): 
C H N 
______________________________________ 
Calculated (%): 51.56 6.29 10.93 
Observed (%): 51.41 6.20 10.65 
Specific rotation: [.alpha.].sub.D.sup.23 = -86.5 (CHCl.sub.3, C = 2.0) 
Infra-red absorption spectrum: .gamma..sub.max.sup.CHCl.sbsp.3 
(cm.sup.-1) 
1780, 1745, 1680, 1630 
N.M.R. spectrum: .delta. CDCl.sub.3 
Note: ( ) indicates the coupling 
constant (Hz). 1.17 [t 3H (S)] 1.97 
(S 1.94H) 2.03 (S 0.59H) 2.30 (m 0.48H), 
2.66-3.59 (m 4H) 3.83 (S 3H) 4.30 (m 1H) 
5.06 (brs 0.2H) 7.10 (brs 1H) 14.97 (brs 
0.8H) 
Thin layer chromatography: 
Using a silica gel plate (Merck) and 
benzene/ethyl acetate (1:1 by volume), a single 
spot was observed (Rf = 0.33). 
______________________________________ 
From these data, this oily substance was identified as 
(4S)-ethyl-.alpha.-(4-methoxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(acetyl 
) acetamide. When subjected to the FeCl.sub.3 colour reaction on the thin 
layer chromatography plate, this substance becomes brown. Also, the N.M.R. 
spectrum reveals a signal of a proton (.delta.14.97) which is exchangeable 
with deuterated methanol. 
These facts indicate the presence of this substance mainly in enol form. 
EXAMPLE 6 
Preparation of 
(4S)-ethyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(acet 
yl) acetamide, i.e. 
##STR31## 
L-aspartic acid-.alpha.-benzyl ester (1.27 g, 5.7 millimole) suspended in 
methanol (20 ml) was added to 40% aqueous pyruvaldehyde (0.56 ml, 3.0 
millimole) and ethylisonitrile (330 mg, 6.0 millimole). The mixture was 
stirred at room temperature for 48 hours, followed by stirring at 
45.degree. C. for 2 hours. After the removal of insoluble materials, the 
solvent was removed by distillation under reduced pressure. An oily 
substance was obtained, which was transferred to a column (diameter about 
4 cm) packed with 120 g of silica gel (Q23) to effect purification by 
column chromatography. A solvent mixture of benzene and ethyl acetate (160 
ml 5:1 by volume) was passed through the column and then elution was 
effected using a solvent mixture of benzene and ethyl acetate (2:1 by 
volume). The eluate was divided into 8 ml fractions. Fractions 45 to 90 
were collected and combined and the solvent was evaporated off under 
reduced pressure to yield an oily substance (350 mg) having the following 
physical characteristics. 
______________________________________ 
Elemental analysis as C.sub.17 H.sub.20 N.sub.2 O.sub.5 
(molecular weight 332.35): 
C H N 
______________________________________ 
Calculated (%): 61.44 6.07 8.43 
Observed (%): 61.65 6.28 8.43 
Specific rotation: [.alpha.].sub.D.sup.23 = -66.7 (CHCl.sub.3, C = 0.86) 
Infra-red absorption spectrum: .gamma..sub.max.sup.CHCl.sbsp.3 
(cm.sup.-1) 
1780, 1740, 1690, 1625 
N.M.R. spectrum: .delta. CDCl.sub.3 
Note: ( ) indicates the coupling 
constant (Hz), 1.17 [t 3H (8)] 1.94 
(S 2.22H) 2.06 (S 0.36H) 2.26 (S 0.42H) 
3.03-3.59 (m 2H) 4.36 (m 1H) 5.23 (S 2H) 
7.13 (brs 1H) 7.36 (S 5H) 14.95 (brs 1H) 
Thin layer chromatography: 
Using a silica gel plate (Merck) and 
benzene/ethyl acetate (1:1 by volume), a single 
spot (Rf = 0.53) was observed. 
______________________________________ 
From these data, this oily substance was identified as 
(4S)-ethyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(acet 
yl) acetamide. This substance becomes brown on being subjected to the 
FeCl.sub.3 colour reaction on the thin layer chromatography plate, while 
the N.M.R. spectrum reveals a signal of a proton (.delta.14.95) which is 
exchangeable with deuterated methanol. 
These facts indicate the presence of this substance mainly in enol form. 
EXAMPLE 7 
Preparation of 
3,4-erythro-ethyl-.alpha.-(4-t-butoxycarbonyl-3-t-butoxy-2-oxoazetidine-1y 
l)-.alpha.-(acetyl) acetamide i.e. 
##STR32## 
Erythro-.beta.-t-butoxy-DL-aspartic acid .alpha.-t-butyl ester (750 mg, 3 
millimole) dissolved in a mixture of chloroform (30 ml) and water (30 ml) 
was added to 40% aqueous pyruvaldehyde (0.56 ml 3 millimole) and 
ethylisonitrile (165 mg, 3 millimole) and was stirred under nitrogen at 
room temperature for 72 hours. After completion of the reaction, the 
chloroform phase of the reaction solution was combined with another 
chloroform phase obtained by extracting the aqueous phase twice using 20 
ml portions of chloroform. The combined solutions were washed twice using 
20 ml portions of a saturated solution of sodium chloride and the 
chloroform phase was then dried over Glauber's salt. The residue was 
transferred to a column (diameter about 3 cm) packed with 40 g of silica 
gel (Q23). Purification was effected by column chromatography using a 
solvent mixture of benzene and ethyl acetate (2:1 by volume). The eluate 
was divided into 3 ml fractions. Fractions 21 to 50 were collected and 
combined. The solvent was evaporated off under reduced pressure giving 
crystals (180 mg) having the following physical characteristics. 
Melting point: 119.degree.-120.degree. C. 
______________________________________ 
Elemental analysis as C.sub.18 H.sub.30 N.sub.2 O.sub.6 
(molecular weight 370.44) 
C H N 
______________________________________ 
Calculated (%): 58.36 8.16 7.56 
Observed (%): 58.15 8.12 7.46 
Infra-red absorption spectrum: .gamma. .sub.max.sup.KBr (cm.sup.-1) 
1790 (sh), 1780, 1720 1620 (br) 
N.M.R. spectrum: .delta. CD.sub.3 OD--CDCl.sub.3 
Note: ( ) indicates the coupling 
constant (Hz). 1.17 [t 3 H (8)] 1.30 
(S 9 H) 1.53 (S 9H) 2.0 (S 2.6H) 2.33 
(brs 0.4H) 3.30 [q 2H (8)] 4.0 [d 1H 
(2)] 4.80 [d 1H (2)] 
Thin layer chromatography: 
Using a silica gel plate (Merck) and 
benzene/ethyl acetate (1:1, by volume), a single 
spot was observed (Rf = 0.74). 
______________________________________ 
From these data, the crystals were identified as 
3,4-erythro-ethyl-.alpha.-(4-t-butoxycarbonyl-3-t-butoxy-2-oxoazetidine-1- 
yl)-.alpha.-(acetyl) acetamide. This substance becomes brown when subjected 
to the FeCl.sub.3 colour reaction on the thin layer chromatography plate, 
while the N.M.R. spectrum reveals a single peak (.delta.14.97) which is 
exchangeable with deuterated methanol. 
These facts indicate the presence of this substance mainly in enol form. 
EXAMPLE 8 
Preparation of 
(4S)-ethyl-.alpha.-(4-methoxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(phenyl 
) acetamide, i.e. 
##STR33## 
L-aspartic acid-.alpha.-methyl ester (4.41 g, 30 millimole) suspended in 
methanol (200 ml) was added to benzaldehyde (3.18 g, 30 millimole) and 
ethylisonitrile (1.82 g, 33 millimole). The mixture was stirred under 
nitrogen at room temperature for 48 hours. After completion of the 
reaction, the solvent was evaporated off under reduced pressure to given 
an oily substance which was then transferred to a column (diameter about 8 
cm) packed with 600 g of silica gel (Q23) to effect purification by column 
chromatography. The eluate was divided into 12 ml fractions and fractions 
1 to 72, 73 to 88 and 89 to 260 were eluted using solvent systems of 
hexane/ethyl acetate (1:2 by volume) hexane/ethyl acetate (1:3 by volume) 
and ethyl acetate/methanol (200:1 by volume) respectively. Fractions 71 to 
221 were collected and combined and the solvent was removed by 
distillation to yield crystals (4.17 g) having the following physical 
characteristics [yield 47.9%]. 
______________________________________ 
Elemental analysis as C.sub.15 H.sub.18 N.sub.2 O.sub.4 
(molecular weight 290.31): 
C H N 
______________________________________ 
Calculated (%): 62.05 6.25 9.65 
Observed (%): 61.77 6.38 9.37 
Infra-red absorption spectrum: .gamma..sub.max.sup.KBr (cm.sup.-1) 
1740-1770, 1670, 1660 
N.M.R. spectrum: .delta. CDCl.sub.3 
Note: ( ) indicates the coupling 
constant (Hz). 
1.06 [t 1.35H (7)] 1.20 [t 1.65H (7)] 
2.67-3.63 (m 4 H) 3.40 (S 1.65H) 3.73 
(S 1.35H) 3.8-4.57 (m 1 H) 5.35 (S 
1.65 H) 5.42 (S 1.35 H) 7.30, 7.35 (2S 5H) 
6.4-7.9 (1H) 
Thin layer chromatography: 
Using a silica gel plate (Merck) and 
benzene/ethyl acetate (1:1, by volume), two spots 
were observed (Rf = 0.30 and Rf = 0.36). 
______________________________________ 
EXAMPLE 9 
Preparation of 
(4S)-phenyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(phe 
nyl) acetamide, i.e. 
##STR34## 
L-aspartic acid-.alpha.-benzyl ester (40 g 179.2 millimole) was suspended 
in methanol (1.3 liter) and was added to benzaldehyde (19 g, 179.2 
millimole) and phenylisonitrile (19.4 g, 188.2 millimole). The mixture was 
stirred under nitrogen at room temperature for 64 hours. After the removal 
of the solvent by distillation under reduced pressure, the resulting oily 
substance was added to a saturated sodium chloride solution (500 ml) and 
ethyl acetate (500 ml) to effect extraction. The ethyl acetate layer was 
washed three times using a saturated sodium chloride solution and dried 
over Glauber's salt. After the removal of the solvent by distillation 
under reduced pressure, the resulting oily substance was transferred to a 
column (diameter about 8 cm) packed with 600 g of silica gel (C-200 
obtainable from Wako Junyaku K. K. Japan), to effect purification by 
column chromatography using a solvent system of n-hexane/ethyl acetate 
(1:1, by volume). The eluate was divided into 18 ml fractions. Fractions 
79 to 129 were collected and combined and the solvent was removed by 
distillation under reduced pressure to yield a glassy substance having the 
following physical characteristics. 
______________________________________ 
Elemental analysis as C.sub.25 H.sub.22 N.sub.2 O.sub.4 
(molecular weight 414.44): 
C H N 
______________________________________ 
Calculated (%): 72.45 5.35 6.76 
Observed (%): 72.57 5.50 6.57 
Infra-red absorption spectrum: .gamma..sub.max.sup.CHCl.sbsp.3 
(cm.sup.-1) 
1780 (sh), 1770, 1750 (sh), 1695, 1602 
N.M.R. spectrum: .delta. CDCl.sub.3 
Note: ( ) indicates the coupling 
constant (Hz). 
2.67-3.50 (m 2 H), 3.87, 4.53 [each t 
(4.0), dd (2.5, 5.5), 1H], 4.83, 5.15, 
5.20 (each S 1H), 5.50, 5.57 (each 
S 1 H), 6.87-7.80 (m 15H) 8.73, 9.80 
(each brs 1H) 
Mass spectrum: 
M.sup.+ +1 415; M.sup.+ 414, 294, 266, 204, 91 
Thin layer chromatography: 
Using a silica gel plate (Merck) and 
n-hexane/ethyl acetate (1:1 by volume), a single spot 
was observed (Rf = 0.54). 
______________________________________ 
From these data, the obtained glassy substance was identified as 
(4S)-phenyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(phe 
nyl) acetamide [yield: 29.7%]. 
EXAMPLE 10 
Preparation of 
(4S)-phenyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(3-m 
ethoxyphenyl) acetamide, i.e. 
##STR35## 
L-aspartic acid-.alpha.-benzyl ester (2.25 g, 10 millimole) was suspended 
in methanol (80 ml) and was added to m-anisaldehyde (1.36 g, 10 millimole) 
and phenylisonitrile (1.08 g, 10 millimole). The mixture was stirred under 
nitrogen at room temperature for 45 hours. An oily substance obtained by 
removing the solvent under reduced pressure, was transferred to a column 
(diameter about 5 cm) packed with C-200 silica gel (250 g). Purification 
was carried out by column chromatography using a solvent system of 
n-hexane/ethyl acetate (3:2, by volume). The eluate was divided into 15 ml 
fractions. Fractions 61 to 93 were collected and combined and the solvent 
was evaporated off under reduced pressure to give an oily substance (1.05 
g) having the following physical characteristics. 
______________________________________ 
Elemental analysis as C.sub.26 H.sub.24 N.sub.2 O.sub.5 
(molecular weight 444.47): 
C H N 
______________________________________ 
Calculated (%): 70.25 5.44 6.30 
Observed (%): 70.33 5.75 6.19 
Infra-red absorption spectrum: .gamma..sub.max.sup.CHCl.sbsp.3 
(cm.sup.-1) 
1780 (sh), 1770, 1750 (sh), 1695, 1602 
N.M.R. spectrum: .delta. CDCl.sub.3 
Note: ( ) indicates the coupling 
constant (Hz). 2.73-3.50 (m 2H), 3.67, 
3.70 (each S 3H), 3.90, 4.57 [each t 
(4.0), dd (2.5, 5.5), 1H], 4.87, 5.17, 
5.20 (each S 2H), 5.47, 5.53 (each S 1H), 
6.67-7.83 (m 14H), 8.70, 9.80 (each brs 
1H) 
Mass spectrum: 
M.sup.+ 444, 324, 296, 234, 91 
Thin layer chromatography: 
Using a silica gel plate (Merck) and n- 
hexane/ethyl acetate (1:1, by volume), single spot 
was observed (Rf = 0.54). 
______________________________________ 
From these data, the oily substance was identified as 
(4S)-phenyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1yl)-.alpha.-(3-me 
thoxyphenyl)acetamide [yield: 23.6%] 
EXAMPLE 11 
Preparation of 
(4S)-phenyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(5-m 
ethylfuranyl-2-yl) acetamide, i.e. 
##STR36## 
L-aspartic acid-.alpha.-benzyl ester (2.23 g, 10 millimole) suspended in 
methanol (80 ml) was added to 5-methylfurfural (1.1 g, 10 millimole) and 
phenylisonitrile (1.08 g, 10.5 millimole). The mixture was stirred at room 
temperature for 6 days. An oily substance was obtained by removing the 
solvent under reduced pressure. This substance was transferred to a column 
(diameter about 6 cm) packed with 350 g of silica gel (C-200) for 
purification. Elution is effected using a solvent system of n-hexane/ethyl 
acetate (3:2, by volume). The eluate was divided into 10 ml. fractions and 
fractions 80 to 129 were collected and combined and the solvent was 
evaporated off under reduced pressure to give an oily substance (558 mg) 
having the following physical characteristics. 
______________________________________ 
Elemental analysis as C.sub.24 H.sub.22 N.sub.2 O.sub.5 
(molecular weight 418.43) 
C H N 
______________________________________ 
Calculated (%): 68.89 5.30 6.70 
Observed (%): 69.22 5.41 6.55 
Infra-red absorption spectrum: .gamma..sub.max.sup.CHCl.sbsp.3 
(cm.sup.-1) 
1780 (sh), 1770, 1740, 1700, 1603 
N.M.R. spectrum: .delta..sup.CDCl.sbsp.3 Note: ( ) indicates the 
coupling constant (Hz). 
2.10, 2.16 (each S, 3H), 2.77-3.53 (m, 2H), 3.97, 
4.59 (each m, 1H), 4.97, 5.23 (each brs, 2H), 
5.53, 5.57 (each S, 1H), 5.83 (m, 1H), 6.26 
(m, 1H), 6.80-7.80 (m, 10H), 8.63, 9.97 
(each brs, 1H) 
Mass spectrum: (m/e) 
M.sup.+ 418, 298, 270, 208, 91 
Thin layer chromatography: 
Using a silica gel plate (Merck) and n-hexane/ 
ethyl acetate (1:1, by volume), two spots were 
observed (Rf = 0.58 and Rf = 0.61). 
______________________________________ 
From these data, the oily substance was identified as 
(4S)-phenyl-.alpha.-(4-benzyloxy-carbonyl-2-oxoazetidine-1-yl)-.alpha.-(5- 
methylfuran-2-yl)acetamide [yield: 13.8%]. 
EXAMPLE 12 
Preparation of 
(4S)-methyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(phe 
nyl) acetate, i.e. 
##STR37## 
Quinoline (18 ml, 152.0 millimole) was added, under anhydrous condition at 
a temperature of 0.degree. C., to anhydrous chloroform (340 ml) containing 
phosphorus pentachloride (15.83 g, 76.0 millimole), and the solution was 
added, at 0.degree. C. over 20 minutes, to 
(4S)-phenyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(phe 
nyl)-acetamide (21.0 g, 50.7 millimole) consisting of a diastereomeric 
mixture (ratio of about 1:1), prepared as in Example 9 and dissolved in 
anhydrous chloroform (80 ml). The reaction mixture was stirred at from 
0.degree. to 5.degree. C. for 3 hours. The solution was added to anhydrous 
methanol (300 ml) at 0.degree. C. and stirred at room temperature for 3 
hours. After this, the solution was added at 0.degree. C. to 1 N HCl (400 
ml) and methanol (300 ml), followed by stirring at room temperature for 1 
hour. About 60% of the solution was removed by distillation under reduced 
pressure. The remaining solution was extracted using three 250 ml portions 
of ethyl acetate, the ethyl accetate phase was washed three times using a 
saturated solution of sodium chloride and the organic phase was dried over 
Glauber's salt. By removing the solvent under reduced pressure, an oily 
substance was obtained, which was transferred to a column (diameter about 
8 cm) packed with C-200 silica gel (650 g). In order to purify it by 
column chromatography, a mixture of hexane/ethyl acetate (1.4 liter, 5:2, 
by volume) was passed through the column, followed by elution using a 
solvent mixture of hexane/ethyl acetate (3:2, by volume). The eluate was 
divided into 15 ml fractions. Fractions 63 to 104 was collected and 
combined and the solvent was evaporated off under reduced pressure to give 
an oily substance (7.9 g, yield 44.4%). The oily substance obtained from 
Fractions 74 to 104 has the following physical characteristics. 
______________________________________ 
N.M.R. spectrum: .delta..sup.CDCl.sbsp.3 [the 
coupling constant (Hz) is indicated in ( )] 
______________________________________ 
2.83 [dd, 0.5H (2.5, 14.0)], 3.07 [d, 1H (4.0)], 
3.12 [dd, 0.5H (5.5, 14.0)], 3.60 (S, 1.5H), 
3,70 (S, 1.5H), 4.23 [t, 0.5H(4.0)], 4.42 
[dd, 0.5H (2.5, 5.5)], 4.70 (brs, 1H), 5.20 
(S, 1H), 5.50 (S, 1H), 7.20-7.40 (m, 10H) 
Infra-red absorption spectrum: .gamma..sub.max.sup.CHCl.sbsp.3 
(cm.sup.-1) 
1780 (sh), 1775, 1750, 1740 (sh) 
Mass spectrum: (m/e) 
M.sup.+ 353, 294, 266, 91 
Thin layer chromatography: 
Using a silica gel plate (Merck) and hexane/ 
ethyl acetate (1:1, by volume), two spots were 
observed (Rf = 0.52 and Rf = 0.61). 
______________________________________ 
From these data, the oily substance obtained was identified as 
(4S)-methyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(phe 
nyl) acetate consisting of a diastereomeric mixture of two compounds in a 
ratio of about 1:1. 
EXAMPLE 13 
Preparation of 
(4S)-methyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(3-m 
ethoxyphenyl) acetate, i.e. 
##STR38## 
Quinoline (0.825 ml, 6.96 millimole) was added, under anhydrous condition 
at a temperature of 0.degree. C., to anhydrous chloroform (15.4 ml) 
containing phosphrus pentachloride (725 mg, 3.48 millimole) and was then 
added, at 0.degree. C. over 10 minutes, to anhydrous chloroform (6 ml) 
containing 
(4S)-phenyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(3-m 
ethoxyphenyl) acetamide (1.03 g, 2.32 millimole), in Example 10. The 
reaction mixture was stirred for 31/2 hours at 0.degree. C. and was then 
added to anhydrous methaol (14 ml) at 0.degree. C. After stirring at room 
temperature for 3 hours, the solution was added to 1 N HCl (18 ml) and 
methanol (18 ml) at 0.degree. C. and was stirred at room temperature for 1 
hour. About 60% of the solvent was removed by distillation under reduced 
pressure and the remaining solution was extracted using three 30 ml 
portions of ethyl acetate. The organic phase was washed three times using 
a saturated solution of sodium chloride and was dried over Glauber's salt. 
By removing the solvent under reduced pressure, an oily substance was 
obtained which was transferred to a column (diameter about 4 cm) packed 
with C-200 silica gel (120 g) and was purified by column chromatography 
using a solvent system of hexane/ethyl acetate (3:2, by volume). The 
eluate was divided into 6 ml fractions. Fractions 56 to 82 were collected 
and combined and the solvent was removed by evaporation under reduced 
pressure to give an oily substance (473 mg) in a yield of 53.2%. The oily 
substance obtained from fractions 66 to 82 has the following physical 
characteristics. 
______________________________________ 
N.M.R. spectrum: .delta..sup.CDCl.sbsp.3 [The 
coupling constant (Hz) is indicated in ( ).] 
______________________________________ 
2.85 [dd, 2/3 H (2.5, 15.0)], 3.07 [d, 2/3 H 
(4.0)], 3.27 [dd, 2/3 H(5.5, 15.0)], 3.63 
(S, 1H), 3.40 (S, 5H), 4.23 [t, 1/3 H(4.0)], 
4.45 [dd, 2/3 H (2.5, 5.5)], 4.72, 4.74 (AB 
doublet, 4/3 H), 5.20 (S, 2/3H), 5.48 (brs, 1H), 
6.70-7.40 (m, 9H) 
Infra-red absorption spectrum: .gamma..sub.max.sup.CHCl.sbsp.3 
(cm.sup.-1) 
1780 (sh), 1770, 1750, 1740 (sh), 1600, 1590 
Mass spectrum: (m/e) 
M.sup.+ 383, M+1:384, 324, 296, 91 
Thin layer chromatography: 
Using a silica gel plate (Merck) and hexane/ethyl 
acetate (1:1, by volume), two spots (Rf = 0.47 and 
Rf = 0.51) were observed, which suggested a ratio of 
about 2:1. 
______________________________________ 
From these data, the oily substance was identified as 
(4S)-methyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(3-m 
ethoxyphenyl) acetate consisting of a diastereomeric mixture of two 
compounds in a ratio of about 2:1. Similarly, an oily substance obtained 
from fractions 56 to 82 was identified as a diastereomeric mixture of two 
compounds in a ratio of about 1:1. 
EXAMPLE 14 
Preparation of 
(4S)-methyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(5-m 
ethylfuran-2-yl) acetate, i.e. 
##STR39## 
Quinoline (0.46 ml, 3.87 millimole) was added, under anhydrous conditions 
at 0.degree. C., to anhydrous chloroform (8.6 ml) containing phosphorus 
pentachloride (403 mg, 1.94 millimole) and was then added over 10 minutes, 
to anhydrous chloroform (6 ml) containing 
(4-S)-phenyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(5- 
methylfuran-2-yl) acetamide (540 ml, 1.29 millimole) prepared as in Example 
11. The solution was stirred at 0.degree. C. for 31/2 hours and was then 
added to methanol, followed by stirring at room temperature for 1 hour. 
About 60% of the solvent was evaporated off under reduced pressure and the 
remaining solution was extracted using three 30 ml portions of ethyl 
acetate. The organic phase was washed three times using a saturated 
solution of sodium chloride and was dried over Glauber's salt. 
The solvent was removed under reduced pressure to give an oily substance 
which was then transferred to a column (diameter about 3 cm) packed with 
60 g of C-200 silica gel. The substance was purified by column 
chromatography using a solvent system of hexane/ethyl acetate. The eluate 
was divided into 3 ml fractions and fractions 55 to 72 were collected and 
combined and the solvent was evaporated off under reduced pressure to give 
an oily substance (191 mg) in a yield of 41.4%. An oily substance obtained 
from fractions 60 to 65 has the following physical characteristics. 
______________________________________ 
N.M.R. spectrum: .delta. CDCl.sub.3 
Note: ( ) indicates the coupling constant (Hz). 
2.17 (S, 1.8H), 2.23 (S, 1.2H), 2.87 [dd, 0.6H 
(2.5, 14.5)], 3.10 [d, 0.8H (4.0)] 3.30 [dd, 
0.6H (5.0, 14.5)], 3.65 (S, 1.2H), 3.73 (S, 
1.8H), 4.18 [t, 0.4H (4.0)], 4.53 [dd, 0.6H 
(2.5, 5.0)], 4.90, 4.93 (AB doublet, 1.2H), 
5.20, (S, 0.8H), 5.57 (S, 1H), 5.87 (m, 1H), 
6.17 [d, 0.6H (3.0)], 6.23 [d, 0.4H (3.0)], 
7.30 (S, 2H), 7.37 (S, 3H) 
Infra-red absorption spectrum: .gamma..sub.max.sup.CHCl.sbsp.3 
(cm.sup.-1) 
1780 (sh), 1770, 1755, 1740 (sh) 
Mass spectrum: (m/e) 
M.sup.+ 357, 329, 298, 270, 91 
Thin layer chromatography: 
Using a silica gel plate (Merck) and benzene/ethyl 
acetate (1:1, by volume), a single spot was observed 
(Rf = 0.49). 
______________________________________ 
From these data, the oily substance was identified as 
(4S)-methyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(5-m 
ethylfuran-2-yl) acetate consisting of two diastereomeric isomers in a 
ratio of about 2:3. 
Similarly, an oily substance obtained from fractions 52 to 72 was 
identified as a diastereomeric mixture of two compounds in a ratio of 
about 2:3. 
EXAMPLE 15 
Preparation of 
(4S)-methyl-.alpha.-(4-carboxyl-2-oxazetidine-1-yl)-.alpha.-(phenyl) 
acetate, i.e. 
##STR40## 
(4S)-methyl-.alpha.-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(phen 
yl) acetate (4.0 g, 11.3 millimole) consisting of a diastereomeric mixture 
(ratio about 1:1) prepared as in Example 12, was dissolved in dioxane (250 
ml), to which was added 10% palladium/carbon catalyst (1.0 g). The 
solution was stirred at room temperature under atmospheric pressure for 17 
hours while nitrogen was passed through the solution. The catalyst was 
removed and the solvent was evaporated off under reduced pressure to give 
an oily substance (2.89 g) having the following physical characteristics. 
______________________________________ 
N.M.R. spectrum: .delta. CHCl.sub.3 [The coupling constant (Hz) is 
indicated in ( ).] 
2.70-3.50 (m, 2H), 3.70, 373 (each S, 5H 4.07- 
4.50 (m, 1H), 5.47, 5.53 (each S, 1H), 7.30, 
7.33 (each S, 5 H) 
Infra-red absorption spectrum: .gamma..sub.max.sup.CHCl.sbsp.3 
(cm.sup.-1) 
1780 (sh), 1775, 1755, 1740 (sh), 1730 (sh), 
1710 (sh) 
Thin layer chromatography: 
Using a silica gel plate (Merck) and benzene/ethyl acetate/ 
acetic acid (6:2:1, by volume), a single spot was observed 
(Rf = 0.32). 
______________________________________ 
From these data, the oily substances was identified as 
(4S)-methyl-.alpha.-(4-carboxyl-2-oxoazetidine-1-yl)-.alpha.-(phenyl) 
acetate consisting of a diastereomeric mixture of two compounds in a ratio 
of about 1:1 (yield: 97.0%). 
EXAMPLE 16 
Preparation of 
(4S)-methyl-.alpha.-(4-carboxyl-2-oxoazetidine-1-yl).alpha.-(3-methoxyphen 
yl) acetate, 
##STR41## 
(4S)-methyl-60 
-(4-benzyloxycarbonyl-2-oxoazetidine-1-yl)-.alpha.-(3-methoxyphenyl) 
acetate (470 mg, 1.23 millimole) consisting of a diastereomeric mixture 
(ratio about 1:1), prepared as in Example 13, was dissolved in dioxane (25 
ml), to which 10% palladium/carbon catalyst (100 mg) was added. The 
mixture was stirred at room temperature under atmospheric pressure for 14 
hours, while nitrogen was passed through the solution. The catalyst was 
removed from the reaction mixture and the solvent was removed under 
reduced pressure to give an oily substance (354 mg) having the following 
physical characteristics. 
______________________________________ 
N.M.R. spectrum: .delta. CHCl.sub.3 [The coupling constant (Hz) 
is indicated in ( ).] 
2.73-3.50 (m 2H), 3.70-3.80 (m, 6H), 4.13- 
4.50 (m, 1H), 5.47 (S, 0.5H), 5.53 (S, 0.5H), 
6.75-7.47 (m, 4H) 
Infra-red absorption spectrum: .gamma..sub.max.sup.CHCl.sbsp.3 
(cm.sup.-1) 
1780 (sh), 1770, 1750, 1740 (sh), 1730 (sh), 
1710 (sh), 1600, 1590 
Thin layer chromatography: 
Using a silica gel plate (Merck) and benzene/ethyl 
acetate/acetic acid (6:2:1, by volume), a single spot 
was observed (Rf = 0.26). 
______________________________________ 
From these data, the oily substance was identified as 
(4S)-methyl-.alpha.-(4-carboxyl-2-oxoazetidine-1-yl)-.alpha.-(3-methoxyphe 
nyl) acetate consisting of a diastereomeric mixture of two compounds (ratio 
about 1:1) [yield 98.0%]. 
EXAMPLE 17 
Preparation of 
(4S)-methyl-.alpha.-(4-carboxyl-2-oxoazetidine-1-yl)-.alpha.-(5-methylfura 
n-2-yl) acetate, i.e. 
##STR42## 
(4S)-methyl-.alpha.-(4-benzyloxycarbonyl-2-oxazetidine-1-yl)-.alpha.-(5-met 
hylfuran-2-yl) acetate (180 mg, 0.5 millimole) consisting of a 
diastereomeric mixture (ratio about 2:3), prepared as in Example 14, was 
dissolved in dioxane (12.5 ml). To the mixture was added 10% 
palladium/carbon catalyst (50 ml). Nitrogen was passed through the 
solution for 14 hours, while it was stirred at room temperature under 
atmospheric pressure. After removal of the catalyst, the solvent was 
evaporated off under reduced pressure to give an oily substance (130 mg) 
having the following physical characteristics. 
______________________________________ 
N.M.R. spectrum: .delta. CDCl.sub.3 
Note: ( ) indicates the coupling constant (Hz). 
2.22 (S, 1.8H), 2.27 (S, 1.2H), 2.77- 
3.57 (m, 2H), 3.77 (S, 3H), 4.07- 
4.63 (m, 1H), 5.60 (brs, 1H), 5.93 
(m, 1H), 6.25 [d, 0.6H (3.0)], 
6.32 [d, 0.4H (3.0)] 
Infra-red absorption spectrum: .gamma..sub.max.sup.CHCl.sbsp.3 
(cm.sup.-1) 
1780 (sh), 1770, 1755, 1740 (sh), 1730 (sh), 
1710 
Thin layer chromatography: 
Using a silica gel plate and benzene/ethyl acetate/acetic 
acid (6:2:1, by volume), a single spot was observed 
(Rf = 0.27). 
______________________________________ 
From these data, the oily substance was identified as 
(4S)-methyl-.alpha.-(4-carboxyl-2-oxoazetidine-1-yl)-.alpha.-(5-methylfura 
n-2-yl) acetate consisting of a mixture of two compounds in a ratio of 
about 2:3 [yield 97.0%].