Concise synthesis and antimicrobial activities of new substituted 5-isoxazolpenicillins

Article abstract of DOI:10.1002/jccs.200700092

The synthesis of a series of new 5-isoxazolpenicillins is described, which were obtained by coupling substituted isoxazoles with 6-APA. Concise large-scale synthesis of 3,5-disubstituted isoxazoles by 1,3-dipolar cycloaddition using copper(I) as catalyst was also investigated. Representative compounds were assayed for antimicrobial activities, showing satisfactory antimicrobial activities against Gram-negative bacteria.

Full text of DOI:10.1002/jccs.200700092

Journal of the Chinese Chemical Society, 2007, 54, 643-652
643
Concise Synthesis and Antimicrobial Activities of New Substituted
5-Isoxazolpenicillins
Xi-Zhao Wanga (
Wei-Ren Xub (
Fang-Niu Shib (
), Jiong Jiaa (
), Wei Liub (
) and Jian-Wu Wanga* (
), Yan Zhanga (
),
),
)
aSchool of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, P. R. China
bTianjin Institute of Pharmaceutical Research, Tianjin 300193, P. R. China
The synthesis of a series of new 5-isoxazolpenicillins is described, which were obtained by coupling
substituted isoxazoles with 6-APA. Concise large-scale synthesis of 3,5-disubstituted isoxazoles by 1,3-
dipolar cycloaddition using copper(I) as catalyst was also investigated. Representative compounds were
assayed for antimicrobial activities, showing satisfactory antimicrobial activities against Gram-negative
bacteria.
Keywords: Penicillin; Isoxazole; Synthesis; Antimicrobial activity.
INTRODUCTION
Emergence of penicillinase-producing bacterial strains
cules of medicinal interest and used as important interme-
diates in organic synthesis.3-5 Sharpless found that cop-
per(I) was an effective catalyst for the cycloaddition reac-
tions of nitrile oxides with alkynes to produce isoxazoles,6
and Fokin synthesized a number of 3,5-disubstituted iso-
xazoles in good yields in a analogous manner.7 Given the
bacterial resistance to antibiotics and the frequent genera-
tion of drug-fast bacteria, the development of new antibi-
otic drugs has become urgent.8-10 We therefore undertook a
concise synthetic program in order to improve the synthesis
of 5-isoxazolpenicillins and develop new antimicrobial
agents.
led to the development of the first generation of semi-syn-
thetic penicillinase-resistant penicillin, which achieve their
effectiveness by attaching a bulky substituted isoxazole
fragment to the penicillin molecule, preventing penicil-
linase from entering the penicillin molecule and cleaving
the b-lactam ring.1 The present study in this field focuses
on the structural modification and the improvement of anti-
microbial activity of 4-isoxazolpenicillins (Fig. 1, A), which
contain the 3,5-disubstituted-4-isoxazolyl group. How-
ever, little attention has been paid to substituted 5-isoxazol-
penicillins (Fig. 1, B), except for a few examples, such as
6-[(3-arylisoxazol-5-yl)acetamido]penicillins (Fig. 1, C)
with low yields and a hard work-up procedure.2
RESULTS AND DISCUSSION
Furthermore, considerable progress had been made
recently in the synthesis of isoxazole compounds, since
isoxazole derivatives are often encountered in the mole-
3,5-Disubstituted isoxazoles are important intermedi-
ates for the synthesis of isoxazolpenicillins, and using an
experimentally convenient method, we obtained the re-
Fig. 1. Structures of two kinds of isoxazolpenicillins and an analog.
* Corresponding author. Fax: +86-531-88564464; E-mail: jwwang@sdu.edu.cn

644 J. Chin. Chem. Soc., Vol. 54, No. 3, 2007
Wang et al.
gioselective 3,5-disubstituted isoxazoles on a large-scale
through 1,3-dipolar cycloaddition of nitrile oxides to ace-
tylenes. Although 1,3-dipolar cycloaddition has been known
for a long time,11 its application to the synthesis of isoxa-
zole is scarce. In the reported process (Scheme I, A), the re-
action conditions are variable from several hours at 60-70
°C to several days at ambient temperature and while both
isoxazole regioisomers are usually obtained, the yields of
isoxazole products are often quite low, and side reactions
result in impurities which complicate the isolation and pu-
rification.6
prepared on a large-scale with high yields, and only one
regioisomer was obtained and without tedious chromato-
graphic purification.
Thus, starting from the inexpensive and readily ob-
tainable aryldehydes 1, the corresponding aldoximes 2
were synthesized via the reaction with hydroxylamine
(Scheme II).12 As for chlorination of the aldoximes, previ-
ously reported preparations of imidoyl chlorides required
either the use of chlorine, nitrosyl chloride, t-butyl hypo-
chlorite and a complex experimental procedure utilizing
N-chlorosuccinimide (NCS) in DMF or the hydrogen chlo-
ride/DMF/Oxone.13,14 In this paper, the aldoximes 2 were
readily transformed to the corresponding imidoyl chlorides
3 using NCS/DMF which is suitable for aromatic aldoximes.
The base-induced dehydrohalogenation of imidoyl chlo-
rides 3 produced nitrile oxides that are important interme-
diates in 1,3-dipolar cycloaddition reactions to form isoxa-
zoles. As nitrile oxides are unstable and dimerize readily,5
NCS was added in small portions while maintaining a low
Recently several new catalysts for the 1,3-dipolar cy-
cloaddition reaction of nitrile oxides and alkynes, espe-
cially the copper(I) catalysts, have been found to form iso-
xazole concisely and efficiently. In the presence of a cata-
lytic amount of copper(I), the in situ generated nitrile oxide
undergoes a stepwise addition to a copper(I) acetylenide
under mild reaction conditions (Scheme I, B). By this con-
cise method, 3,5-disubstituted isoxazole compounds were
Scheme I 1,3-Dipolar cycloaddition of nitrile oxides to acetylenes
Scheme II The synthetic strategy to the title compounds
Ar = C6H5 (7a), 4-FC6H4 (7b), 2-ClC6H4 (7c), 4-ClC6H4 (7d), 2-BrC6H4 (7e), 2-CH3OC6H4 (7f),
4-CH3OC6H4 (7g), 2-NO2C6H4 (7h), 4-NO2C6H4 (7i), 3-CF3C6H4 (7j), 4-CF3C6H4 (7k),
2,4-Cl2C6H3 (7l), 3,4-Cl2C6H3 (7m), 2,4,5-Cl3C6H2 (7n), 3,4,5-Cl3C6H2 (7o), pyridin-2-yl (7p),
pyridin-4-yl (7q).

Synthesis and Bio-activities of 5-Isoxazolpenicillins
J. Chin. Chem. Soc., Vol. 54, No. 3, 2007 645
temperature, and nitrile oxides were used without purifica-
tion immediately after they were prepared. The freshly gen-
erated nitrile oxides reacted with propargyl alcohol via
1,3-dipolar cycloaddition in the presence of a catalytic
amount of copper(I), obtained from reduction of copper(II)
sulfate with sodium ascorbate. The 3,5-disubstituted isoxa-
zole products 4 were obtained in moderate to good overall
yields (55-75%) after a simple filtration or extraction.
Utilizing a copper(I)-catalyzed regioselective cyclo-
addition reaction, 3,5-disubstituted isoxazoles 4 were ob-
tained in good yields by a convenient three-step procedure
between in situ generated nitrile oxides and terminal acety-
lenes, and the oxidation of isoxazoles 4 gave the isoxazol-
5-yl carbonic acid compounds 5. So far, there have been
several reagents to achieve the oxidation reaction, such as
KMnO4, K2Cr2O7, and so forth. However, we found that
Jone’s Reagent was the most effective reagent for this reac-
tion with a yield of up to 95% and the work-up procedure
was very simple. The carbonic acids reacted with refluxing
SOCl2 or POCl3 to produce isoxazol-5-yl carbonyl chlo-
rides 6, which coupled with 6-amino-penicillanic acid
(6-APA), the main precursor for the production of penicil-
lin, to yield the title compounds 7 in moderate yields. The
work-up procedure would be very difficult if the starting
material, especially the compounds 5, had a small amount
of impurities, and therefore the purification of isoxazoles 4
through chromatography on silica gel were necessary in
certain cases. In addition, to obtain more pure title com-
pounds, the transformation of penicillanic acids to sodium
salts was often necessary.
Biological Activity
Compounds 7b-7e, 7g, 7i, 7j were selected and
screened in vitro for their antibacterial activity against
Gram positive bacteria (Staphylococcus aureus and Bacil-
lus pumilus) and Gram negative bacteria (Pseudomonass
aureginosa and Klebsiella pneumoniae) employing the
cup-plate method at the concentration of 50 mg/mL in nu-
trient agar media.15 Azithromycin (AZ) and Gentamycin
Sulfate (GS) were used as standard antibacterial agents.
The results which are presented in Table 1 show that most
of the compounds were active against Gram positive bacte-
ria, especially compounds 7b, 7c and 7i showed better in-
hibitory effect to Staphylococcus aureus than AZ; how-
ever, the activities against Gram negative bacteria were
weak. And the investigation on the structure-activity rela-
tionship shows that halogen atoms can enhance the antibac-
terial action of the title compounds. Further investigation
on the biological activity of other compounds is still in
progress.
EXPERIMENTAL
All melting points were determined with an XT-4 mi-
croscopic melting apparatus and are uncorrected. 1H NMR
spectra were recorded on a Bruker Avance DPX400 spec-
trometer with TMS as internal standard. IR spectra were
Table 1. The antibacterial activity of the tested products (7b-7e, 7g, 7i, 7j)
Staphylococcus
Bacillus
Pseudomonass
Klebsiella
NO.
aureus
pumilus
aureginosa
pneumoniae
7b
7c
0.99
0.91
0.62
1.53
0.69
0.93
1.61
1
6.16
5.51
4.07
8.45
4.47
6.88
5.61
1
> 100
90.21
> 100
> 100
> 100
> 100
96.30
92.59
73.53
> 100
84.75
58.14
> 100
69.32
7d
7e
7g
7i
7j
AZa
GSb
1
1
a Azithromycin (AZ) was used as a standard antibacterial agent against Gram positive
bacteria. The concentration is set to 1 ug/mL.
b Gentamycin Sulfate (GS) was used as a standard antibacterial agent against Gram negative
bacteria. The concentration is set to 1 ug/mL.
The activity is presented as the relative value of the concentration with the same activity of
the standard antibacterial agent (1ug/mL).

646 J. Chin. Chem. Soc., Vol. 54, No. 3, 2007
Wang et al.
obtained from a Nicolet 5700 FT-IR spectrophotometer as
KBr pellets. Elemental analyses were performed with an
Elementar EL Vario III analyzer. The mass spectra were
obtained on an API2000 LC-mass spectrometer, utilizing
electrospray ionization technique (ESI). TLC (Thin Layer
Chromatography) analysis was utilized to ascertain the
purities of the products.
mL of water). The reaction mixture was then treated with
KHCO3 (60 mmol) and left to be stirred for 1.5 h at ambient
temperature. The reaction mixture was diluted with water,
and the solid off-white isoxazole product was filtered off
(82-92% yields).
3-Phenyl-5-hydroxymethylisoxazole 4a
Yield: 2.98 g, 85%. m.p. 52-53.5 °C. 1H NMR (CDCl3,
400 MHz): d 2.25 (bs, 1H), 4.75 (s, 2H), 6.40 (s, 1H), 7.32
(m, 3H), 7.73 (m, 2H). Anal. Calcd. for C10H9NO2: C,
68.56; H, 5.18; N, 8.00%. Found: C, 68.70; H, 5.12; N,
7.99%.
1. General Procedure for Preparation of Aromatic
Aldoximes (2a-2q)
To a suspension of aldehydes (100 mmol) in a 1:2
mixture of H2O/MeOH (80 mL) was added hydroxylamine
hydrochloride (100 mmol), followed by adding Na2CO3
(55 mmol). After being stirred at room temperature for 3 h,
was added to the solution 100 mL of water and then ex-
tracted with diethyl ether. The aqueous phase was acidified
to pH 6 by concentrated hydrogen chloride while keeping
the temperature below 30 °C and extracting with ether. The
organic phase was dried over MgSO4, and the solvent was
evaporated to give the oximes in 85-95% yield, which were
used directly in the next step.
3-(4-Fluorophenyl)-5-hydroxymethylisoxazole 4b
Yield: 3.13 g, 81%. m.p. 97-98 °C. 1H NMR (CDCl3,
400 MHz): d 2.24 (bs, 1H), 4.84 (s, 2H), 6.51 (s, 1H), 7.12
(m, 2H), 7.51 (m, 2H). Anal. Calcd. for C10H8FNO2: C,
62.18; H, 4.17; N, 7.25%. Found: C, 62.10; H, 4.12; N,
7.29%.
3-(2-Chlorophenyl)-5-hydroxymethylisoxazole 4c
Yield: 3.35 g, 80%. m.p. 73.5-74 °C. 1H NMR (CDCl3,
400 MHz): d 3.16 (bs, 1H), 4.82 (s, 2H), 6.72 (s, 1H), 7.37
(m, 2H), 7.49 (m, 1H), 7.72 (m, 1H). Anal. Calcd. for
C10H8ClNO2: C, 57.30; H, 3.85; N, 6.68%. Found: C,
57.26; H, 3.88; N, 6.63%.
2. General Procedure for Preparation of Arylhydroxi-
moyl Chloride (3a-3q)
To a solution of oximes (50 mmol) in DMF (20 mL)
was added NCS (10 mmol) in one portion. The beginning
of the reaction caused a slight increase of the reaction tem-
perature. (If the reaction does not start, a small amount of
aqueous HCl in DMF can be added. With the electron-
deficient oximes, the reaction mixture is heated to 45 °C).
The remaining 40 mmol of NCS was added in small por-
tions while keeping the temperature below 35 °C. The mix-
ture was stirred at room temperature for 1 h, poured into
water, and extracted with diethyl ether. The organic phase
was washed with brine and dried over Na2SO4, and the sol-
vent was removed to give the imidoyl chlorides in 70-90%
yields. They were used directly without further purification
in the next step.
3-(4-Chlorophenyl)-5-hydroxymethylisoxazole 4d
Yield: 3.44 g, 82%. m.p. 99.5-100 °C. 1H NMR (CDCl3,
400 MHz): d 2.74 (bs, 1H), 4.79 (s, 2H), 6.51 (s, 1H), 7.41
(m, 2H), 7.79 (m, 2H). Anal. Calcd. for C10H8ClNO2: C,
57.30; H, 3.85; N, 6.68%. Found: C, 57.21; H, 3.84 N,
6.65%.
3-(2-Bromophenyl)-5-hydroxymethylisoxazole 4e
Yield: 3.05 g, 75%. m.p. 82-83 °C. 1H NMR (CDCl3,
400 MHz): d 3.16 (bs, 1H), 4.73 (s, 2H), 6.58 (s, 1H), 7.24-
7.31 (m, 3H), 7.64 (m, 1H). Anal. Calcd. for C10H8BrNO2:
C, 47.27; H, 3.17; N, 5.51%. Found: C, 47.19; H, 3.25; N,
5.60%.
3. General Procedure for Copper(I)-Catalyzed Syn-
thesis of 3,5-Disubstituted Isoxazoles (4a-4q)
Arylhydroximoyl chloride (20 mmol) and propargyl
alcohol (22 mmol) were dissolved in 50 mL of a 1:1 tert-
BuOH/H2O mixture. While the mixture was being stirred,
sodium ascorbate (2 mmol in 3 mL of water) was added,
followed by copper(II) sulfate pentahydrate (0.6 mmol in 2
3-(2-Methoxyphenyl)-5-hydroxymethylisoxazole 4f
Yield: 3.12 g, 76%. m.p. 74-75 °C. 1H NMR (CDCl3,
400 MHz): d 3.25 (bs, 1H), 3.83 (s, 3H), 4.76 (s, 2H), 6.71
(s, 1H), 6.93-7.01 (m, 3H), 7.40 (m, 1H). Anal. Calcd. for
C11H11NO3: C, 64.38; H, 5.40; N, 6.83%. Found: C, 64.33;

Synthesis and Bio-activities of 5-Isoxazolpenicillins
H, 5.36 N, 6.85%.
J. Chin. Chem. Soc., Vol. 54, No. 3, 2007 647
400 MHz): d 2.45 (bs, 1H), 4.81 (s, 2H), 6.51 (s, 1H), 7.38-
7.66 (m, 3H). Anal. Calcd. for C10H7Cl2NO2: C, 49.21; H,
2.89; N, 5.74%. Found: C, 49.24; H, 2.96; N, 5.70%.
3-(4-Methoxyphenyl)-5-hydroxymethylisoxazole 4g
Yield: 3.03 g, 74%. m.p. 89-90.5 °C. 1H NMR (CDCl3,
400 MHz): d 1.88 (bs, 1H), 3.85 (s, 3H), 4.81 (s, 2H), 6.51
(s, 1H), 7.02 (m, 2H), 7.39 (m, 2H). Anal. Calcd. for
C11H11NO3: C, 64.38; H, 5.40; N, 6.83%. Found: C, 64.43;
H, 5.42 N, 6.86%.
(2,4,5-Trichlorophenyl)-5-hydroxymethylisoxazole 4n
Yield: 4.23 g, 76%. m.p. 121-122 °C. 1H NMR (CDCl3,
400 MHz): d 2.16 (bs, 1H), 4.85 (s, 2H), 6.57 (s, 1H), 7.68
(s, 1H), 7.79 (s, 1H). Anal. Calcd. for C10H6Cl3NO2: C,
43.12; H, 2.17; N, 5.03%. Found: C, 43.11; H, 2.20; N,
5.12%.
3-(3-Nitrophenyl)-5-hydroxymethylisoxazole 4h
1
Yield: 3.09 g, 70%. m.p. 134-134.5 °C. H NMR
(CDCl3, 400 MHz): d 1.96 (bs, 1H), 4.81 (s, 2H), 6.77 (s,
1H), 7.56 (m, 1H), 7.95 (m, 2H), 8.39 (m, 1H). Anal. Calcd.
for C10H8N2O4: C, 54.55; H, 3.66; N, 12.72%. Found: C,
54.48; H, 3.61 N, 12.70%.
(3,4,5-Trichlorophenyl)-5-hydroxymethylisoxazole 4o
Yield: 4.12 g, 74%. m.p. 135-136 °C. 1H NMR (CDCl3,
400 MHz): d 2.27 (bs, 1H), 4.84 (s, 2H), 6.58 (s, 1H), 7.78
(d, J = 1.9, 2H). Anal. Calcd. for C10H6Cl3NO2: C, 43.12;
H, 2.17; N, 5.03%. Found: C, 43.19; H, 2.11; N, 5.08%.
3-(4-Nitrophenyl)-5-hydroxymethylisoxazole 4i
Yield: 3.21 g, 73%. m.p. 145-146 °C. 1H NMR (CDCl3,
400 MHz): d 2.29 (bs, 1H), 4.87 (s, 2H), 6.58 (s, 1H), 7.98
(m, 2H), 8.35 (m, 2H). Anal. Calcd. for C10H8N2O4: C,
54.55; H, 3.66; N, 12.72%. Found: C, 54.53; H, 3.60 N,
12.76%.
3-(Pyridin-2-yl)-5-hydroxymethylisoxazole 4p16
1
Yield: 2.53 g, 72%. m.p. 100-100.5 °C. H NMR
(CDCl3, 400 MHz): d 2.77 (bs, 1H), 4.82 (s, 2H), 6.91 (s,
1H), 7.57-8.65 (m, 4H). Anal. Calcd. for C9H8N2O2: C,
61.36; H, 4.58; N, 15.90%. Found: C, 61.39; H, 4.61; N,
15.88%.
3-3-(Trifluoromethyl)phenyl-5-hydroxymethylisoxazole
4j
3-(Pyridin-4-yl)-5-hydroxymethylisoxazole 4q
Yield: 3.41 g, 70%. m.p. 86-87 °C. 1H NMR (CDCl3,
400 MHz): d 3.16 (bs, 1H), 4.85 (s, 2H), 6.59 (s, 1H), 7.49
(m, 2H), 7.98 (m, 2H). Anal. Calcd. for C11H8F3NO2: C,
54.33; H, 3.32; N, 5.76%. Found: C, 54.41; H, 3.40; N,
5.71%.
Yield: 2.48 g, 71%. m.p. 105-106 °C. 1H NMR (CDCl3,
400 MHz): d 2.59 (bs, 1H), 4.84 (s, 2H), 6.90 (s, 1H), 8.01-
8.63 (m, 4H). Anal. Calcd. for C9H8N2O2: C, 61.36; H,
4.58; N, 15.90%. Found: C, 61.31; H, 4.64; N, 15.93%.
4. General Procedure for Synthesis of Isoxazol-5-yl
Carbonic Acid (5a-5q)
3-4-(Trifluoromethyl)phenyl-5-hydroxymethylisoxazole
4k
To a solution of 3,5-disubstituted isoxazoles (20
mmol) in acetone (25 mL) at 0 °C was added the Jones re-
agent (40 mmol) dropwise. After stirring at the same tem-
perature for 0.5 h, the reaction mixture was allowed to
stand at 35 °C for another 3 h. This mixture was diluted
with water and extracted with ether. The combined organic
phases were dried over anhydrous Na2SO4, filtered, and
evaporated to give the desired carbonic acid compound 5
(95-98% yields).
Yield: 3.45 g, 71%. m.p. 96-97.5 °C. 1H NMR (CDCl3,
400 MHz): d 2.25 (bs, 1H), 4.83 (s, 2H), 6.53 (s, 1H), 7.57
(m, 2H), 7.92 (m, 2H). Anal. Calcd. for C11H8F3NO2: C,
54.33; H, 3.32; N, 5.76%. Found: C, 54.26; H, 3.35; N,
5.74%.
3-(2,4-Dichlorophenyl)-5-hydroxymethylisoxazole 4l
Yield: 3.85 g, 79%. m.p. 115-116 °C. 1H NMR (CDCl3,
400 MHz): d 2.47 (bs, 1H), 4.82 (s, 2H), 6.69 (s, 1H), 7.42-
7.75 (m, 3H). Anal. Calcd. for C10H7Cl2NO2: C, 49.21; H,
2.89; N, 5.74%. Found: C, 49.25; H, 2.94; N, 5.71%.
3-Phenyl-5-isoxazolylcarboxylic acid 5a
Yield: 3.70, 97%. m.p. 176-177 °C. 1H NMR (DMSO,
400 MHz): d 7.58-7.98 (m, 5H), 7.64 (s, 1H), 14.10 (bs,
1H). IR (KBr): u 3425 (OH, acid), 1750 (C=O, acid), 1432
(isoxazolyl ring) cm-1. Anal. Calcd. for C10H7NO3: C,
3-(3,4-Dichlorophenyl)-5-hydroxymethylisoxazole 4m
Yield: 3.81 g, 78%. m.p. 106-107 °C. 1H NMR (CDCl3,

648 J. Chin. Chem. Soc., Vol. 54, No. 3, 2007
Wang et al.
63.49; H, 3.73; N, 7.40%. Found: C, 63.56; H, 3.71; N,
7.44%.
(bs, 1H). IR (KBr): u 3433 (OH, acid), 1751 (C=O, acid),
1430 (isoxazolyl ring) cm-1. Anal. Calcd. for C11H9NO4: C,
60.27; H, 4.14; N, 6.39%. Found: C, 60.23; H, 4.09; N,
6.44%.
3-(4-Fluorophenyl)-5-isoxazolylcarboxylic acid 5b
Yield: 3.93, 95%. m.p. 197-197.5 °C. 1H NMR (DMSO,
400 MHz): d 7.39 (m, 2H), 7.81 (s, 1H), 8.04 (m, 2H), 14.30
(bs, 1H). IR (KBr): u 3435 (OH, acid), 1754 (C=O, acid),
1433 (isoxazolyl ring) cm-1. Anal. Calcd. for C10H6FNO3:
C, 57.98; H, 2.92; N, 6.76%. Found: C, 57.94; H, 3.01; N,
6.74%.
3-(3-Nitrophenyl))-5-isoxazolylcarboxylic acid 5h
Yield: 4.53, 96%. m.p. 223-222 °C. 1H NMR (DMSO,
400 MHz): d 8.03-8.46 (m, 4H), 7.93 (s, 1H), 14.30 (bs,
1H). IR (KBr): u 3435 (OH, acid), 1759 (C=O, acid), 1437
(isoxazolyl ring) cm-1. Anal. Calcd. for C10H6N2O5: C,
51.29; H, 2.58; N, 11.96%. Found: C, 51.36; H, 2.49; N,
11.91%.
3-(2-Chlorophenyl)-5-isoxazolylcarboxylic acid 5c
Yield: 4.23, 95%. m.p. 176-177 °C. 1H NMR (DMSO,
400 MHz): d 7.68-8.06 (m, 4H), 7.71 (s, 1H), 14.34 (bs,
1H). IR (KBr): u 3436 (OH, acid), 1753 (C=O, acid), 1436
(isoxazolyl ring) cm-1. Anal. Calcd. for C10H6ClNO3: C,
53.71; H, 2.70; N, 6.26%. Found: C, 53.74; H, 2.76; N,
6.29%.
3-(4-Nitrophenyl)-5-isoxazolylcarboxylic acid 5i
Yield: 4.60, 97%. m.p. 242-243 °C. 1H NMR (DMSO,
400 MHz): d 7.90 (s, 1H), 8.01 (m, 2H), 8.44 (m, 2H), 14.53
(bs, 1H). IR (KBr): u 3438 (OH, acid), 1760 (C=O, acid),
1439 (isoxazolyl ring) cm-1. Anal. Calcd. for C10H6N2O5:
C, 51.29; H, 2.58; N, 11.96%. Found: C, 51.35; H, 2.62; N,
11.99%.
3-(4-Chlorophenyl)-5-isoxazolylcarboxylic acid 5d
Yield: 4.25, 95%. m.p. 185-186 °C. 1H NMR (DMSO,
400 MHz): d 7.64 (m, 2H), 7.75 (s, 1H), 8.05 (m, 2H), 14.60
(bs, 1H). IR (KBr): u 3437 (OH, acid), 1753 (C=O, acid),
1430 (isoxazolyl ring) cm-1. Anal. Calcd. for C10H6ClNO3:
C, 53.71; H, 2.70; N, 6.26%. Found: C, 53.65; H, 2.73; N,
6.31%.
3-3-(Trifluoromethyl)phenyl-5-isoxazolylcarboxylic
acid 5j
Yield: 4.98, 97%. m.p. 156-157 °C. 1H NMR (DMSO,
400 MHz): d 7.64 (s, 1H), 7.66-7.97 (m, 4H), 14.54 (bs,
1H). IR (KBr): u 3430 (OH, acid), 1755 (C=O, acid), 1437
(isoxazolyl ring) cm-1. Anal. Calcd. for C11H6F3NO3: C,
51.37; H, 2.35; N, 5.45%. Found: C, 51.43; H, 2.39; N,
5.41%.
3-(2-Bromophenyl)-5-isoxazolylcarboxylic acid 5e
Yield: 5.12, 96%. m.p. 172-172.5 °C. 1H NMR (DMSO,
400 MHz): d 7.48-7.98 (m, 4H), 7.88 (s, 1H), 14.54 (bs,
1H). IR (KBr): u 3436 (OH, acid), 1751 (C=O, acid), 1434
(isoxazolyl ring) cm-1. Anal. Calcd. for C10H6BrNO3: C,
44.81; H, 2.26; N, 5.23%. Found: C, 44.90; H, 2.31; N,
5.28%.
3-4-(Trifluoromethyl)phenyl-5-isoxazolylcarboxylic
acid 5k
Yield: 4.86, 95%. m.p. 176-177 °C. 1H NMR (DMSO,
400 MHz): d 7.72-8.05 (m, 4H), 7.63 (s, 1H), 14.34 (bs,
1H). IR (KBr): u 3438 (OH, acid), 1754 (C=O, acid), 1439
(isoxazolyl ring) cm-1. Anal. Calcd. for C11H6F3NO3: C,
51.37; H, 2.35; N, 5.45%. Found: C, 51.41; H, 2.31; N,
5.42%.
3-(2-Methoxyphenyl)-5-isoxazolylcarboxylic acid 5f
Yield: 4.29, 98%. m.p. 165-166 °C. 1H NMR (DMSO,
400 MHz): d 7.39-7.94 (m, 4H), 7.63 (s, 1H), 14.46 (bs,
1H). IR (KBr): u 3431 (OH, acid), 1755 (C=O, acid), 1431
(isoxazolyl ring) cm-1. Anal. Calcd. for C11H9NO4: C,
60.27; H, 4.14; N, 6.39%. Found: C,60.24; H, 4.11; N,
4.19%.
3-(2,4-Dichlorophenyl)-5-isoxazolylcarboxylic acid 5l
Yield: 5.06, 99%. m.p. 168-169 °C. 1H NMR (DMSO,
400 MHz): d 7.59-8.02 (m, 3H), 7.71 (s, 1H), 14.64 (bs,
1H). IR (KBr): u 3436 (OH, acid), 1753 (C=O, acid), 1432
(isoxazolyl ring) cm-1. Anal. Calcd. for C10H5Cl2NO3: C,
46.54; H, 1.95; N, 5.43%. Found: C, 46.58; H, 1.98; N,
5.40%.
3-(4-Methoxyphenyl)-5-isoxazolylcarboxylic acid 5g
Yield: 4.26, 97%. m.p. 181-182 °C. 1H NMR (DMSO,
400 MHz): d 7.37 (m, 2H), 7.60 (s, 1H), 7.96 (m, 2H), 14.61

Synthesis and Bio-activities of 5-Isoxazolpenicillins
J. Chin. Chem. Soc., Vol. 54, No. 3, 2007 649
3-(3,4-Dichlorophenyl)-5-isoxazolylcarboxylic acid 5m
Yield: 4.99, 98%. m.p. 191-192 °C. 1H NMR (DMSO,
400 MHz): d 7.54-7.89 (m, 3H), 7.82 (s, 1H), 14.60 (bs,
1H). IR (KBr): u 3434 (OH, acid), 1753 (C=O, acid), 1436
(isoxazolyl ring) cm-1. Anal. Calcd. for C10H5Cl2NO3: C,
46.54; H, 1.95; N, 5.43%. Found: C, 46.52; H, 1.99; N,
5.48%.
of dry acetone, which was used directly in next step.
6. General Procedure for the Synthesis of 5-Isoxazol-
penicillins (7a-7q)
A stirred suspension of 6-APA (7 mmol) in water (15
mL) was adjusted to pH 7.0-7.5 with 1 N aqueous sodium
hydroxide at 0 °C and with a buffer function of Na2HPO4
solution. The resulting solution was treated with the ace-
tone solution of isoxazol-5-yl carbonyl chloride (7 mmol)
prepared in the procedure above below -5 °C, and was ad-
justed to pH 7.5-8.0 with saturated NaHCO3 solution. After
stirring vigorously at the same temperature for 1 h, the re-
action was allowed to stand at 20 °C for another 3 h. This
mixture was diluted with water and acidified to pH 2.5 by
adding 10% hydrochloric acid while keeping the tempera-
ture below 25 °C and extracting with ethyl acetate. The or-
ganic phase was washed with brine, dried over MgSO4 and
was concentrated under reduced pressure. Adding petro-
leum ether to the above concentrated solution, the precipi-
tated solid was filtered off and dissolved in a little ethyl ac-
etate. Sodium isooctanoate was added and stored below -5
°C overnight; pale powder was filtrated and dried to obtain
isoxazolpenicillin.
(2,4,5-Trichlorophenyl)-5-isoxazolylcarboxylic acid 5n
Yield: 5.56, 96%. m.p. 196 °C (dec.). 1H NMR (DMSO,
400 MHz): d 7.48-7.98 (m, 2H), 7.84 (s, 1H), 14.54 (bs,
1H). IR (KBr): u 3435 (OH, acid), 1756 (C=O, acid), 1438
(isoxazolyl ring) cm-1. Anal. Calcd. for C10H4Cl3NO3: C,
41.06; H, 1.38; N, 4.79%. Found: C, 41.01; H, 1.37; N,
4.74%.
(3,4,5-Trichlorophenyl)-5-isoxazolylcarboxylic acid 5o
Yield: 5.64, 98%. m.p. 185-186 °C. 1H NMR (DMSO,
400 MHz): d 7.86 (d, J = 2.0, 2H), 7.79 (s, 1H), 14.50 (bs,
1H). IR (KBr): u 3431 (OH, acid), 1757 (C=O, acid), 1436
(isoxazolyl ring) cm-1. Anal. Calcd. for C10H4Cl3NO3: C,
41.06; H, 1.38; N, 4.79%. Found: C, 50.41; H, 3.50; N,
9.74%.
3-(Pyridin-2-yl)-5-isoxazolylcarboxylic acid 5p
Yield: 3.61, 95%. m.p. 210 °C (dec.). 1H NMR (DMSO,
400 MHz): d 7.59-8.65 (m, 4H), 7.87 (s, 1H), 14.90 (bs,
1H). IR (KBr): u 3429 (OH, acid), 1756 (C=O, acid), 1434
(isoxazolyl ring) cm-1. Anal. Calcd. for C9H6N2O3: C,
56.85; H, 3.18; N, 14.73%. Found: C, 56.81; H, 3.15; N,
14.76%.
6-(3-Phenylisoxazole-5-carboxamido)-penicillanate so-
dium 7a
Yield: 2.03 g, 71%. m.p. 133 °C (dec.). IR (KBr): u
3406 (NH, amide), 1791 (C=O, lactam), 1682 (C=O, am-
ide), 1606 (C=O, carboxylate ion), 1575 (NH, amide),
1
1560, 1434 (isoxazolyl ring) cm-1. H NMR (D2O, 400
MHz): d 1.64 (s, 3H), 1.75 (s, 3H), 4.56 (s, 1H), 5.65 (d, J =
4.0 Hz, 1H), 5.88 (d, J = 4 Hz, 1H), 7.30 (s, 1H), 7.51 (m,
2H), 7.81 (m, 2H). ESI-MS: m/z 409 (M+), 411 (M++2).
Anal. Calcd. for C18H16N3NaO5S: C, 52.81; H, 3.94; N,
10.26%. Found: C, 52.69; H, 4.05; N, 10.30%.
3-(Pyridin-4-yl)-5-isoxazolylcarboxylic acid 5q
Yield: 3.67, 96%. m.p. 204 °C (dec.). 1H NMR (DMSO,
400 MHz): d 8.02-8.69 (m, 4H), 7.89 (s, 1H), 14.84 (bs,
1H). IR (KBr): u 3436 (OH, acid), 1757 (C=O, acid), 1435
(isoxazolyl ring) cm-1. Anal. Calcd. for C9H6N2O3: C,
56.85; H, 3.18; N, 14.73%. Found: C, 56.89; H, 3.11; N,
14.68%.
6-3-(4-Fluorophenyl)isoxazole-5-carboxamido-penicil-
lanate sodium 7b
Yield: 2.04 g, 68%. m.p. 112 °C (dec.). IR (KBr): u
3401 (NH, amide), 1795 (C=O, lactam), 1697 (C=O, am-
ide), 1608 (C=O, carboxylate ion), 1578 (NH, amide),
5. General Procedure for Synthesis of 3,5-Disubsti-
tuted Isoxazol-5-yl Carbonyl Chlorides (6a-6q)
1
1558, 1439 (isoxazolyl ring) cm-1. H NMR (D2O, 400
A mixture of isoxazol-5-yl carboxylic acid (8 mmol)
and SOCl2 (6 mL) was heated under reflux for 7 h. The ex-
cess SOCl2 was removed with a water vacuum pump and
the residue was distilled in vacuo to give carbonyl chlo-
rides (over 85% yield). The product was dissolved in 10 mL
MHz): d 1.65 (s, 3H), 1.76 (s, 3H), 4.53 (s, 1H), 5.63 (d, J =
4.1 Hz, 1H), 5.86 (d, J = 4.0 Hz, 1H), 7.22 (m, 2H), 7.31 (s,
1H), 7.61 (m, 2H). ESI-MS: m/z 427 (M+). Anal. Calcd. for
C18H15FN3NaO5S: C, 50.59; H, 3.54; N, 9.83%. Found: C,
50.41; H, 3.50; N, 9.74%.

650 J. Chin. Chem. Soc., Vol. 54, No. 3, 2007
Wang et al.
6-3-(2-Chlorophenyl)isoxazole-5-carboxamido-penicil-
lanate sodium 7c
6-3-(4-Methoxyphenyl)isoxazole-5-carboxamido-penicil-
lanate sodium 7g
Yield: 2.17 g, 70%. m.p. ~145 °C (dec.). IR (KBr): u
3411 (NH, amide), 1797 (C=O, lactam), 1692 (C=O, am-
ide), 1607 (C=O, carboxylate ion), 1574 (NH, amide),
Yield: 2.34 g, 76%. m.p. 124 °C (dec.). IR (KBr): u
3411 (NH, amide), 1784 (C=O, lactam), 1672 (C=O, am-
ide), 1602 (C=O, carboxylate ion), 1572 (NH, amide),
1
1
1556, 1434 (isoxazolyl ring) cm-1. H NMR (D2O, 400
1551, 1424 (isoxazolyl ring) cm-1. H NMR (D2O, 400
MHz): d 1.64 (s, 3H), 1.75 (s, 3H), 4.56 (s, 1H), 5.66 (d, J =
4.1 Hz, 1H), 5.89 (d, J = 4.2 Hz, 1H), 7.30 (s, 1H), 7.39-
7.74 (m, 4H). ESI-MS: m/z 443 (M+), 445 (M++2). Anal.
Calcd. for C18H15ClN3NaO5S: C, 48.71; H, 3.41; N, 9.47.
Found: C, 48.78; H, 3.55; N, 9.55%.
MHz): d 1.61 (s, 3H), 1.72 (s, 3H), 3.84 (s, 3H), 4.54 (s,
1H), 5.64 (d, J = 4.2 Hz, 1H), 5.84 (q, J = 4.3 Hz, 1H), 6.97
(m, 2H), 7.32 (s, 1H), 7.74 (m, 2H). ESI-MS: m/z 439 (M+).
Anal. Calcd. for C19H18N3NaO6S: C, 51.93; H, 4.13; N,
9.56%. Found: C, 51.81; H, 4.09; N, 9.39%.
6-3-(4-Chlorophenyl)isoxazole-5-carboxamido-penicil-
lanate sodium 7d
6-3-(3-Nitrophenyl)isoxazole-5-carboxamido-penicil-
lanate sodium 7h
Yield: 2.48 g, 80%. m.p. 155 °C (dec.). IR (KBr): u
3415 (NH, amide), 1798 (C=O, lactam), 1691 (C=O, am-
ide), 1604 (C=O, carboxylate ion), 1571 (NH, amide),
Yield: 2.57 g, 81%. m.p. 160 °C (dec.). IR (KBr): u
3430 (NH, amide), 1789 (C=O, lactam), 1686 (C=O, am-
ide), 1606 (C=O, carboxylate ion), 1579 (NH, amide),
1
1
1555, 1433 (isoxazolyl ring) cm-1. H NMR (D2O, 400
1557, 1434 (isoxazolyl ring) cm-1. H NMR (D2O, 400
MHz): d 1.62 (s, 3H), 1.78 (s, 3H), 4.54 (s, 1H), 5.64 (d, J =
4.2 Hz, 1H), 5.84 (d, J = 4.2 Hz, 1H), 7.32 (s, 1H), 7.44 (m,
2H), 7.75 (m, 2H). ESI-MS: m/z 443 (M+), 445 (M++2).
Anal. Calcd. for C18H15ClN3NaO5S: C, 48.71; H, 3.41; N,
9.47. Found: C, 48.65; H, 3.31; N, 9.36%.
MHz): d 1.63 (s, 3H), 1.74 (s, 3H), 4.55 (s, 1H), 5.65 (d, J =
4.4 Hz, 1H), 5.86 (d, J = 4.4 Hz, 1H), 7.30 (s, 1H), 7.69 (m,
1H), 8.06-8.34 (m, 3H). ESI-MS: m/z 454 (M+), 455
(M++1). Anal. Calcd. for C18H15N4NaO7S: C, 47.58; H,
3.33; N, 12.33%. Found: C, 47.65; H, 3.36; N, 12.19%.
6-3-(2-Bromophenyl)isoxazole-5-carboxamido-penicil-
lanate sodium 7e
6-3-(4-Nitrophenyl)isoxazole-5-carboxamido-penicil-
lanate sodium 7i
Yield: 2.45 g, 72%. m.p. 132 °C (dec.). IR (KBr): u
3424 (NH, amide), 1791 (C=O, lactam), 1686 (C=O, am-
ide), 1606 (C=O, carboxylate ion), 1573 (NH, amide),
Yield: 2.60 g, 82%. m.p. 153 °C (dec.). IR (KBr): u
3427 (NH, amide), 1788 (C=O, lactam), 1691 (C=O, am-
ide), 1607 (C=O, carboxylate ion), 1577 (NH, amide),
1
1
1559, 1429 (isoxazolyl ring) cm-1. H NMR (D2O, 400
1560, 1436 (isoxazolyl ring) cm-1. H NMR (D2O, 400
MHz): d 1.64 (s, 3H), 1.75 (s, 3H), 4.55 (s, 1H), 5.65 (d, J =
4.0 Hz, 1H), 5.88 (d, J = 4.0 Hz, 1H), 7.33 (s, 1H), 7.48-
7.84 (m, 4H). ESI-MS: m/z 487 (M+), 489 (M++2). Anal.
Calcd. for C18H15BrN3NaO5S: C, 44.28; H, 3.10; N, 8.61%.
Found: C, 44.20; H, 3.02; N, 8.54%.
MHz): d 1.63 (s, 3H), 1.73 (s, 3H), 4.55 (s, 1H), 5.64 (d, J =
4.2 Hz, 1H), 5.84 (d, J = 4.2 Hz, 1H), 7.32 (s, 1H), 8.01-
8.35 (m, 4H). ESI-MS: m/z 454 (M+), 455 (M++1). Anal.
Calcd. for C18H15N4NaO7S: C, 47.58; H, 3.33; N, 12.33%.
Found: C, 47.39; H, 3.25; N, 12.26%.
6-3-(2-Methoxyphenyl)isoxazole-5-carboxamido-penicil-
lanate sodium 7f
6-3-(3-Trifluoromethylphenyl)isoxazole-5-carboxamido-
penicillanate sodium 7j
Yield: 2.18 g, 71%. m.p. 103 °C (dec.). IR (KBr): u
3406 (NH, amide), 1786 (C=O, lactam), 1678 (C=O, am-
ide), 1601 (C=O, carboxylate ion), 1577 (NH, amide), 1550,
1421 (isoxazolyl ring) cm-1. 1H NMR (D2O, 400 MHz): d
1.64 (s, 3H), 1.74 (s, 3H), 3.91 (s, 3H), 4.56 (s, 1H), 5.65 (d,
J = 4.3 Hz, 1H), 5.88 (d, J = 4.3 Hz, 1H), 7.02 (m, 2H), 7.29
(s, 1H), 7.51 (m, 1H), 7.90 (m, 1H). ESI-MS: m/z 439 (M+),
440 (M++1). Anal. Calcd. for C19H18N3NaO6S: C, 51.93; H,
4.13; N, 9.56%. Found: C, 51.86; H, 4.06; N, 9.44%.
Yield: 2.23 g, 67%. m.p. 89 °C (dec.). IR (KBr): u
3403 (NH, amide), 1781 (C=O, lactam), 1686 (C=O, am-
ide), 1606 (C=O, carboxylate ion), 1571 (NH, amide),
1
1561, 1439 (isoxazolyl ring) cm-1. H NMR (D2O, 400
MHz): d 1.64 (s, 3H), 1.75 (s, 3H), 4.56 (s, 1H), 5.65 (d, J =
4.4 Hz, 1H), 5.88 (d, J = 4.4 Hz, 1H), 7.30 (s, 1H), 7.48-
7.94 (m, 4H). ESI-MS: m/z 477 (M+). Anal. Calcd. for
C19H15F3N3NaO5S: C, 47.80; H, 3.17; N, 8.80%. Found: C,
47.66; H, 3.08; N, 8.67%.

Synthesis and Bio-activities of 5-Isoxazolpenicillins
J. Chin. Chem. Soc., Vol. 54, No. 3, 2007 651
6-3-(4-Trifluoromethylphenyl)isoxazole-5-carboxamido-
penicillanate sodium 7k
8.11%.
Yield: 2.13 g, 64%. m.p. 105 °C (dec.). IR (KBr): u
3409 (NH, amide), 1780 (C=O, lactam), 1681 (C=O, am-
ide), 1604 (C=O, carboxylate ion), 1576 (NH, amide),
6-3-(3,4,5-Trichlorophenyl)isoxazole-5-carboxamido-
penicillanate sodium 7o
Yield: 2.39 g, 67%. m.p. 146 °C (dec.). IR (KBr): u
3426 (NH, amide), 1793 (C=O, lactam), 1703 (C=O, am-
ide), 1606 (C=O, carboxylate ion), 1578 (NH, amide),
1
1567, 1436 (isoxazolyl ring) cm-1. H NMR (D2O, 400
MHz): d 1.64 (s, 3H), 1.75 (s, 3H), 4.56 (s, 1H), 5.65 (d, J =
4.2 Hz, 1H), 5.88 (d, J = 4.2 Hz, 1H), 7.31 (s, 1H), 7.41 (m,
2H), 7.94 (m, 2H). ESI-MS: m/z 477 ( M+). Anal. Calcd. for
C19H15F3N3NaO5S: C, 47.80; H, 3.17; N, 8.80%. Found: C,
47.69; H, 3.08; N, 8.75%.
1
1554, 1441 (isoxazolyl ring) cm-1. H NMR (D2O, 400
MHz): d 1.64 (s, 3H), 1.75 (s, 3H), 4.56 (s, 1H), 5.65 (d, J =
4.4 Hz, 1H), 5.88 (d, J = 4.2 Hz, 1H), 7.30 (d, 1H), 7.31 (s,
1H), 7.82 (d, J = 1.9, 2H). ESI-MS: m/z 511 (M+), 513
(M++2), 515 (M++4), 517 (M++6). Anal. Calcd. for
C18H13Cl3N3NaO5S: C, 42.17; H, 2.56; N, 8.20%. Found:
C, 42.01; H, 2.47; N, 8.13%.
6-3-(2,4-Dichlorophenyl)isoxazole-5-carboxamido-
penicillanate sodium 7l
Yield: 2.40 g, 72%. m.p. 141 °C (dec.). IR (KBr): u
3417 (NH, amide), 1796 (C=O, lactam), 1701 (C=O, am-
ide), 1608 (C=O, carboxylate ion), 1581 (NH, amide),
6-3-(Pyridin-2-yl)isoxazole-5-carboxamido-penicillanate
sodium 7p
1
1559, 1439 (isoxazolyl ring) cm-1. H NMR (D2O, 400
Yield: 2.01 g, 70%. m.p. 101 °C (dec.). IR (KBr): u
3423 (NH, amide), 1794 (C=O, lactam), 1713 (C=O, am-
ide), 1605 (C=O, carboxylate ion), 1582 (NH, amide),
MHz): d 1.62 (s, 3H), 1.74 (s, 3H), 4.56 (s, 1H), 5.65 (d, J =
4.2 Hz, 1H), 5.88 (d, J = 4.2 Hz, 1H), 7.31 (s, 1H), 7.49-
7.85 (m, 3H). ESI-MS: m/z 477 (M+), 479 (M++2), 481
(M++4). Anal. Calcd. for C18H14Cl2N3NaO5S: C, 45.20; H,
2.95; N, 8.79%. Found: C, 45.11; H, 2.79; N, 8.66%.
1
1558, 1436 (isoxazolyl ring) cm-1. H NMR (D2O, 400
MHz): d 1.64 (s, 3H), 1.76 (s, 3H), 4.56 (s, 1H), 5.65 (d, J =
4.4 Hz, 1H), 5.88 (d, J = 4.4 Hz, 1H), 7.34 (s, 1H), 7.59-
8.68 (m, 4H). ESI-MS: m/z 410 (M+). Anal. Calcd. for
C17H15N4NaO5S: C, 49.75; H, 3.68; N, 13.65%. Found: C,
49.66; H, 3.59; N, 13.61%.
6-3-(3,4-Dichloropheny)isoxazole-5-carboxamido-peni-
cillanate sodium 7m
Yield: 2.44 g, 73%. m.p. 123 °C (dec.). IR (KBr): u
3431 (NH, amide), 1799 (C=O, lactam), 1701 (C=O, am-
ide), 1608 (C=O, carboxylate ion), 1581 (NH, amide),
6-3-(Pyridin-4-yl)isoxazole-5-carboxamido-penicillanate
sodium 7q
1
1559, 1439 (isoxazolyl ring) cm-1. H NMR (D2O, 400
Yield: 2.23 g, 71%. m.p. 89 °C (dec.). IR (KBr): u
3429 (NH, amide), 1789 (C=O, lactam), 1714 (C=O, am-
ide), 1608 (C=O, carboxylate ion), 1581 (NH, amide),
MHz): d 1.64 (s, 3H), 1.75 (s, 3H), 4.56 (s, 1H), 5.65 (d, J =
4.2 Hz, 1H), 5.88 (d, J = 4.2 Hz, 1H), 7.31 (s, 1H), 7.38-
7.66 (m, 3H). ESI-MS: m/z 477 (M+), 479 (M++2), 481
(M++4). Anal. Calcd. for C18H14Cl2N3NaO5S: C, 45.20; H,
2.95; N, 8.79%. Found: C, 45.15; H, 2.87; N, 8.68%.
1
1551, 1438 (isoxazolyl ring) cm-1. H NMR (D2O, 400
MHz): d 1.66 (s, 3H), 1.77 (s, 3H), 4.56 (s, 1H), 5.64 (d, J =
4.4 Hz, 1H), 5.89 (d, J = 4.4 Hz, 1H), 7.35 (s, 1H), 8.01-
8.63 (m, 4H). ESI-MS: m/z 410 (M+). Anal. Calcd. for
C17H15N4NaO5S: C, 49.75; H, 3.68; N, 13.65%. Found: C,
49.69; H, 3.58; N, 13.53%.
6-3-(2,4,5-Trichlorophenyl)isoxazole-5-carboxamido-
penicillanate sodium 7n
Yield: 2.42 g, 68%. m.p. 136 °C (dec.). IR (KBr): u
3423 (NH, amide), 1797 (C=O, lactam), 1706 (C=O, am-
ide), 1609 (C=O, carboxylate ion), 1576 (NH, amide),
ACKNOWLEDGEMENTS
1
1557, 1440 (isoxazolyl ring) cm-1. H NMR (D2O, 400
Mhz): d 1.64 (s, 3H), 1.75 (s, 3H), 4.56 (s, 1H), 5.65 (d, J =
4.2 Hz, 1H), 5.88 (d, J = 4.2 Hz, 1H), 7.33 (s, 1H), 7.78 (s,
1H), 7.85 (s, 1H). ESI-MS: m/z 511 (M+), 513 (M++2), 515
(M++4), 517 (M++6). Anal. Calcd. for C18H13Cl3N3NaO5S:
C, 42.17; H, 2.56; N, 8.20%. Found: C, 42.09; H, 2.43; N,
The authors wish to thank Dr Wei-Ren Xu for anti-
microbial activity test and Dr. Jiong Jia for providing spec-
tral data. Furthermore, the authors would like to express
their appreciation to Tianjin Institute of Pharmaceutical
Research for the support of this study.

652 J. Chin. Chem. Soc., Vol. 54, No. 3, 2007
Wang et al.
2005, 8, 518.
Received June 14, 2006.
9. Chao, S.-J.; Hui, X.-P.; Li, S.; Qiu, Z.-Z.; Xu, P.-F.; Zhang,
Z.-Y.; Wang, Q.; Guan, Z.-W. J. Chin. Chem. Soc. 2005, 52,
539.
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