Synthesis and antibacterial activities of novel C(3)-aminopyrimidinyl substituted cephalosporins including against respiratory tract pathogens

Article abstract of DOI:10.1016/S0960-894X(00)00425-X

The variety of cephalosporins 1 and 2 which possessed C(3)-aminopyrimidinyl substituents were prepared and evaluated for their antibacterial activities. They exhibited excellent in vitro activities especially against respiratory tract pathogens such as penicillin resistant Streptococcus pneumonia, Moraxella catarrhalis and Haemophilus influenza. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0960-894X(00)00425-X

Bioorganic & Medicinal Chemistry Letters 10 (2000) 2123±2127
Synthesis and Antibacterial Activities of Novel
C(3)-Aminopyrimidinyl Substituted Cephalosporins Including
Against Respiratory Tract Pathogensy
Chang-Seok Lee,* Eun-Jung Ryu, Seong Ho Oh, Kyoung-Sook Paek,
Mu Yong Kim and Hasik Youn
Life Science R & D, LG Chemical Ltd, Research Park, Science Town, Taejon 305-380, South Korea
Received 29 May 2000; accepted 14 July 2000
AbstractÐThe variety of cephalosporins 1 and 2 which possessed C(3)-aminopyrimidinyl substituents were prepared and evaluated
for their antibacterial activities. They exhibited excellent in vitro activities especially against respiratory tract pathogens such as
penicillin resistant Streptococcus pneumonia, Moraxella catarrhalis and Haemophilus in¯uenza. # 2000 Elsevier Science Ltd. All
rights reserved.
The cephalosporin antimicrobial agents continue to
play a major role in the treatment of bacterial infections
such as respiratory tract pathogens. Recently, new oral
cephalosporin antibiotics with excellent activities against
Gram-positive and Gram-negative bacteria such as cef-
tibutene,1 cefdinir,2 and FK0413 have been developed
and introduced to clinical practice. However most of the
cephalosporin antibiotics are no longer available against
respiratory tract infections due to resistance problems,
especially caused by penicillin-resistant Streptococcus
pneumonia (PRSP).4 In a previous paper,5 we described
the synthesis and antibacterial activities of cephalo-
sporins which possess ((aminopyrimidiniumyl or ami-
nopyrimidinyl)thio)methyl group at the 3-position of
cephem nucleus. Those compounds exhibited good
activities against Gram-negative strains, but showed
moderate activities against Gram-positive bacteria. We
wish to synthesize new cephalosporins which have not
only a broad spectrum of antibacterial activities, but
also excellent activities against major respiratory tract
community pathogens such as PRSP, H. in¯uenza and
M. catarrhalis. A new class of cephalosporins bearing
C(3)-aminopyrimidinyl substituents was found to exhi-
bit well balanced activities against Gram-positive and
Gram-negative bacteria including the above major
respiratory tract pathogens. Thus, we have prepared a
series of novel compounds which possess the amino-
pyrimidinyl group at the 3-position of cephem nucleus
(Figs. 1 and 2). We report herein the synthesis of these
compounds and their antimicrobial activities.
Chemistry
The compounds 1 from 3-methanesulfonylcephalo-
sporin 3 and aminothiazole 6 were prepared as follows
(Scheme 1). The synthesis of the amine 5 started from
the 3-methanesulfonylcephalosporin 3. The amine 3 was
treated with substituted pyrimidinethiols at 60 ꢀC,
then warmed-up to ambient temperature for 8 h to pro-
duce 3-thiopyrimidine 4. The diphenylmethyl group at
the C-4 position of the compound 4 was removed by
tri¯uoroacetic acid (TFA) and anisole to a€ord the
amine 5. The C-5 chlorination of aminothiazole ring in
compound 6 with N-chlorosuccinimide, protection of
amine to t-butyl carbamate, hydrolysis of ethyl ester using
sodium hydroxide and ®nally tritylation of hydroxyl-
amine produced the acid 7. When X=CH, no chlorina-
tion step was needed. Also when the R group was
propargyl, alkyloxime was prepared by the addition of
propargyl bromide instead of using trityl chloride. The
activated ester 8 was synthesized from the acid 7 by the
addition of diethyl chlorothiophosphate in the presence
of triethylamine. Coupling of the amine 5 and the acti-
vated ester 8 was carried out with treatment of N,O-
bistrimethylsilylacetamide and pyridine in dichloro-
methane to give the coupled product 9, which was treated
yPresented in part at the 39th ICAAC Meeting, San Francisco, CA,
26±29 September, 1999, F-0398.
*Corresponding author. Tel.: +82-42-866-2261; fax: +82-42-861-2566;
e-mail: csleed@lgchem.co.kr
0960-894X/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved.
PII: S0960-894X(00)00425-X

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C.-S. Lee et al. / Bioorg. Med. Chem. Lett. 10 (2000) 2123±2127
Figure 1.
Figure 2.
with TFA and anisole to a€ord the ®nal products 1.
Nucleophiles shown in Figure 1 were prepared using the
methods presented in the previous papers.6a,b Spectral
data for the cephalosporin 1a are given below.
removal of phenylacetyl group, the amine 11. The C-5
chlorination of the aminothiazole ring in compound 12
with N-chlorosuccinimide, protection of amine to t-
butyl carbamate, hydrolysis of ethyl ester using sodium
hydroxide and ®nally tritylation of hydroxylamine pro-
duced the acid 13. When X=H in 13, no chlorination
step was needed. Also when R=Me, no tritylation step
was required. The acid 13 was added to the amine 11
and pyridine at 20 ꢀC, then the subsequent addition of
phosphorous oxychloride (POCl3) a€orded the coupling
product 14. A one-pot sequential hydrolysis/alkylation
of compound 14 gave C-3 chloromethylthio cephalo-
sporin, which was displaced with nucleophiles (pyr-
imidinethiols) in DMF to furnish the compound 15.
Finally, removal of the protecting groups with tri-
¯uoroacetic acid (TFA) and anisole a€orded the
Spectra for 1a: IR (Nujol) 1770cm 1 (carbonyl on b-lac-
tam ring); 1H NMR (d, D2O) 3.68 (ABq, 2H, J=17.6 Hz),
4.08 (s, 3H), 5.41 (d, 1H, J=4.9 Hz), 5.81 (d, 1H, J=
4.9 Hz), 5.85 (s, 1H), 7.02 (s, 1H); Mass (FAB, m/e) 523.
The compounds 2 from the 3-hydroxycephalosporin 10
and the aminothiazole 12 were prepared as follows
(Scheme 2). The synthesis of the 3-acetate 11 started
from the commercially available 3-hydroxycephalo-
sporin 10.7 The enol ester 10 was treated with chloro-
diphenylphosphate and thiolacetic acid to a€ord, after

C.-S. Lee et al. / Bioorg. Med. Chem. Lett. 10 (2000) 2123±2127
2125
Scheme 1. (a) Substituted aminopyrimidine A or B, THF, DMF, 60 ꢀC to RT; (b) TFA, anisole, 0 ꢀC to RT; (c) (1) when R=Me or Et, X=H;
BOC2O, DMAP; NaOH, H2O, EtOH, (2) when R=propargyl, X=H; BOC2O, DMAP, CH2Cl2; NaOH, H2O, EtOH; propargyl bromide, K2CO3,
DMF, (3) when R=H, X=H; BOC2O, DMAP, CH2Cl2; NaOH, H2O, EtOH; TrCl, K2CO3, DMF, (4) when R=H, X=Cl; N-chlorosuccinimide,
DMF; BOC2O, DMAP, CH2Cl2; NaOH, H2O, EtOH; TrCl, K2CO3, DMF; (d) diethyl chlorothiophosphate, Et3N, CH2Cl2, 0 ꢀC to 40 ꢀC; (e) N,O-
bistrimethylsilylacetamide, pyridine, CH2Cl2, 7, 0 ꢀC to 10 ꢀC; (f) TFA, anisole, 0 ꢀC to RT.
cephalosporins 2. Nucleophiles shown in Figure 2 were
prepared by the methods presented in the previous
papers.5,6b,8a,b Spectral data for the cephalosporin 2c
are given below.
against selected organisms. The MIC values for cefdinir
against the same strains are shown for comparison. This
series of new C-3-substituted cephalosporins exhibited
comparable antibacterial activities to cefdinir against
the Gram-positive bacteria such as methicillin resistant
S. aureus and against Gram-negative organisms includ-
ing E. coli. In general, the cephalosporins 2 showed
better activities in S. aureus and E. faecalis compared to
the cephalosporins 1. When M. catarrhalis 25240 was
employed in cephalosporins 2, all of the in vitro anti-
1
Spectra for 2c: IR (Nujol) 1765 cm (carbonyl on b-
lactam ring); 1H NMR (d, D2O) 3.73 (ABq, 2H,
J=17.3 Hz), 4.42 (ABq, 2H, J=14.0 Hz), 5.21 (d, 1H,
J=4.6 Hz), 5.87 (d, 1H, J=4.6 Hz), 6.04 (s, 1H); Mass
(FAB, m/e) 589.
bacterial activities (MIC) of compounds
2 were
0.008 mg/mL or less. Most of the compounds in Table 1
showed much better antibacterial activities in the
respiratory tract pathogens, PRSP, M. catarrhalis and
H. in¯uenza, than those of the reference (cefdinir). It is
worthwhile to note that the compounds 1 series showed
Antibacterial Activities and Discussion
Agar dilution method was used to determine the mini-
mal inhibitory concentration (MIC) of compounds
Table 1. Antibacterial activities of cephalosporins 1 (MIC, mg/mL)a
Compounds
S.a.1
S.a.2
E.f.
E.c.
K.p.
P.v.
S.p.
M.c.
H.i.
1a
1b
1c
1d
1e
1f
1g
0.5
0.25
0.5
0.5
1
0.25
0.25
0.5
4
2
4
4
4
2
2
4
4
>64
8
32
64
64
2
0.031
0.031
0.13
0.13
0.063
0.25
0.063
0.5
0.031
0.5
1
2
2
2
2
1
8
0.13
0.016
0.031
0.031
0.063
0.063
0.5
0.063
0.5
0.031
0.5
0.5
0.25
0.5
0.25
1
0.5
1
4
<0.008
<0.008
0.016
<0.008
<0.008
<0.008
ndb
0.016
0.13
0.031
0.063
0.13
0.5
0.016
1
0.5
8
4
8
1h
Cefdinir
<0.008
0.016
0.063
aS.a.1, Staphylococcus aureus giorgio, methicillin susceptible; S.a.2, Staphylococcus aureus 77, methicillin resistant; E.f., Enterococcus faecalis 29212;
E.c., Escherichia coli 3190Y; K.p., Klebsiella pneumonia 2011E; P.v., Proteus vulgaris 6059; S.p., Streptococcus pneumonia PN010, penicillin resiatant;
M.c., Moraxella catarrhlis 25240; H.i., Haemophilus in¯uenza HIN003, beta-lactamase producing resistant strain.
bnd, not detected.

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C.-S. Lee et al. / Bioorg. Med. Chem. Lett. 10 (2000) 2123±2127
Scheme 2. (a) ClP(O)(OPh)2, Hunig's base, MeCN; AcSH, triethylamine, MeCN; PCl5, pyridine, then isobutyl alcohol, 10ꢁ 15 ꢀC; (b) (1) when
R=Me, X=H; BOC2O, DMAP; NaOH, H2O, EtOH, (2) when R=H, X=H; BOC2O, DMAP; NaOH, H2O, EtOH; TrCl, K2CO3, DMF, (3) when
R=H, X=Cl; N-chlorosuccinimide, DMF; BOC2O, DMAP; NaOH, H2O, EtOH; TrCl, K2CO3, DMF; (c) pyridine, POCl3, CH2Cl2, 20 ꢀC; (d)
ICH2Cl, morpholine, pyridine, PhH, DMF, 20 ꢀC; NaI, DMF, aryl thiol; (e) TFA, anisole, 0 ꢀC to RT.
4 to 16 times better activities against PRSP compared to
that of cefdinir. Oxime-substituted 1a, 1c±e and unsub-
stituted 1b cephalosporins having 2,6-diaminopyrimine
at C-3 exhibited similar potency against both Gram-
positive and Gram-negative bacteria including respiratory
tract pathogens. When 2-amino-4-hydroxy substituted
pyrimidine at C-3 was employed, the antibacterial
activities against PRSP and H. in¯uenza were better in
5-chloro-substituted aminothiazole 1g than in 5-H
aminothiazole 1h. Overall, most of the compounds 1
displayed much better antibacterial activities against
penicillin resistant S. pneumonia, M. caterrhalis and H.
in¯uenza than those of the cefdinir.
excellent activity against E. faecalis compared to that of
cefdinir. The compounds 2c±e,g,h which possessed 5-
chloro (X=Cl) in aminothiazole ring showed lack of
ecacy in Gram-negative bacteria such as Klebsiella
pneumonia and Proteus vulgaris compared to 2a,b,f
which had 5-H (X=H) in the aminothiazole ring.
However 2c±e,g,h exhibited good and balanced activ-
ities against respiratory tract pathogens, PRSP, H.
in¯uenza and M. catarrhalis, compared to the cephalos-
porins 2a,b,f. Among those ®ve compounds, 2c and 2d
showed the most balanced antibacterial activities
against both Gram-positive and Gram-negative bacteria
including PRSP, H. in¯uenza and M. catarrhalis. Some
of the compounds shown in Table 2 exhibited good
pharmacokinetic value and bioavailability. In parti-
cular, the compound 2c showed excellent oral absorp-
tion (Cmax ꢁ13.8 mg/mL) and half life (139 min) in rats
(20 mg/kg administration). Based on the MIC value and
the pharmacokinetic data, the compound 2c proved that
this compound deserves further evaluation for new
oral antibiotics especially against respiratory tract
pathogens.
In general, the compounds 2a±2d (4-pyrimidinethiol
substituents) in Table 2 showed better antibacterial
activities than those of the cephalosporins 2e±2g (2-
pyrimidinethiol substituents). This series of new C-3
substituted cephalosporins exhibited good antibacterial
activities against Gram-positive bacteria such as S. aur-
eus including methicillin resistant S. aureus. It is worth-
while to note that the compounds 2a,c,d showed

C.-S. Lee et al. / Bioorg. Med. Chem. Lett. 10 (2000) 2123±2127
Table 2. Antibacterial activities of cephalosporins 2 (MIC, mg/mL)a
2127
Compounds
S.a.1
S.a.2
E.f.
E.c.
K.p.
P.v.
S.p.
M.c.
H.i.
2a
2b
2c
2d
2e
2f
2g
0.13
0.25
0.13
0.13
0.5
0.13
0.25
0.5
1
4
1
1
4
1
2
4
4
1
64
1
1
4
4
2
4
8
0.031
0.063
0.25
0.25
0.25
0.063
1
0.5
0.5
1
2
1
0.5
8
8
0.13
0.031
0.016
0.25
0.13
0.25
0.031
0.5
0.5
0.13
0.25
0.5
2
1
1
1
4
2
0.5
0.13
0.063
0.13
1
0.5
0.13
0.5
0.5
1
0.5
0.031
0.016
1
0.25
0.016
0.5
2h
Cefdinir
1
0.031
1
0.031
0.063
aS.a.1, Staphylococcus aureus giorgio, methicillin susceptible; S.a.2, Staphylococcus aureus 77, methicillin resistant; E.f., Enterococcus faecalis 29212;
E.c., Escherichia coli 3190Y; K.p., Klebsiella pneumonia 2011E; P.v., Proteus vulgaris 6059; S.p., Streptococcus pneumonia PN010, penicillin resistant;
M.c., Moraxella catarrhalis MCA027, beta-lactamase producing resistant strain; H.i., Haemophilus in¯uenza HIN003, beta-lactamase producing
resistant strain.
3. FK041: Yamamoto, H.; Kawabata, K.; Tawara, S.; Taka-
Acknowledgements
sugi, H.; Tanaka, H. J. Antibiotics 1998, 51, 683.
4. Breiman, R. F.; Betler, J. C.; Tenover, F. C.; Elliott, J. A.;
Facklam, R. R. J. American Medical Association 1994, 271,
1831.
5. For 2e,f,g: Kim, Y.-Z.; Lim, J.-C.; Yeo, J.-H.; Bang, C.-S.;
Kim, W.-S.; Kim, S.-S.; Woo, Y.-M.; Yang, D.-H.; Oh, H. S.;
Nahm, K. J. Med. Chem. 1994, 37, 3828.
We would like to thank the pharmodokinetic group (Dr.
Sunhwa Lee) and microbiology group (Mr. Hyung Yeul
Joo and Seong Baek Lee) for providing in vitro data.
6. (a) For 1a±f: purchased from Aldrich Co. (b) For 1g,h, 2d:
Koppel, H. C.; Springer, R. H.; Robins, R. K.; Cheng, C. C. J.
Org. Chem. 1961, 26, 792.
References and Notes
1. Ceftibutene: Ishikura, K.; Hamashima, Y.; Nakashimizu,
H.; Motokawa, K.; Toshida, T. J. Antibiotics 1994, 47, 466.
2. Cefdinir: Inamoto, Y.; Chiba, T.; Kamimura, T.; Takaya,
T. J. Antibiotics 1988, 41, 828.
7. Yamamoto, Y.; Okonogi, T.; Shibahara, S.; Inoue, S. US
Patent 5,332,731, 1994.
8. (a) For 2a,b,c: purchased from Aldrich Co. (b) For 2e: Levin,
G.; Kalmus, A.; Bergmann, F. J. Org. Chem. 1960, 25, 1752.