Synthesis and?biological evaluation of?1β-methylcarbapenems having cyclic thiourea moieties and?their?related compounds

Article abstract of DOI:10.1016/j.ejmech.2006.02.006

The synthesis of a new series of 1β-methylcarbapenems having cyclic thiourea moieties is described. Their in vitro antibacterial activities against both Gram-positive and Gram-negative bacteria were tested and the effect of substituent on the pyrrolidine

Full text of DOI:10.1016/j.ejmech.2006.02.006

European Journal of Medicinal Chemistry 41 (2006) 825–832
http://france.elsevier.com/direct/ejmech
Original article
Synthesis and biological evaluation of 1β-methylcarbapenems having
cyclic thiourea moieties and their related compounds
T. Han b, J.-H. Cho a, C.-H. Oh a,*
a Medicinal Chemistry Research Center, Korea Institute of Science and Technology, Seoul 130-650, South Korea
b Hawon Pharm. Co., Seoul 135-080, South Korea
Received 27 April 2005; received in revised form 17 February 2006; accepted 27 February 2006
Available online 05 June 2006
Abstract
The synthesis of a new series of 1β-methylcarbapenems having cyclic thiourea moieties is described. Their in vitro antibacterial activities
against both Gram-positive and Gram-negative bacteria were tested and the effect of substituent on the pyrrolidine ring was investigated. A
particular compound (IIId) having piperazine thiourea moiety showed the most potent antibacterial activity.
© 2006 Elsevier SAS. All rights reserved.
Keywords: 1β-Methylcarbapenems; Antibacterial activity; Substituent effects
1. Introduction
thiourea substituted pyrrolidine-3′-ylthio group as a C-2 side
chain and our approach for improvement of antibacterial activ-
ity of the carbapenems is discussed.
The carbapenem compounds which have a (3S)-pyrrolidin-
3-ylthio group at the C-2 position in the carbapenem skeleton
are noted for their broad and potent antibacterial activity [1],
and a large number of derivatives have been synthesized and
investigated with enthusiasm. Among those compounds, pani-
penem [2] and meropenem [3] was the first to be successfully
launched in the market and clinical evaluations are in progress
for S-4661 [4], BO-2727 [5] and DX-8739 [6], which have
enhanced metabolic stability to renal dehydropeptidase-1
(DHP-1) because of the introduction of a 1β-methyl| group to
the carbapenem skeleton for high antibacterial potency. We
were also interested in this pyrroldin-3-ylthio group and re-
ported that the carbapenem compounds which have a pyrroli-
dine-3-ylthio group at the C-2 position in the carbapenem ske-
leton are noted for their broad and potent antibacterial activity,
and a large number of derivatives have been synthesized and
investigated [7–13]. In our previous work [13], the introduction
of thiourea moieties showed potent and well-balanced antibac-
terial activity.
2. Chemistry
Our general synthetic route leading to new carbapenems in-
volved the preparation of appropriately protected thiols con-
taining pyrrolidine ring as a side chain and subsequent cou-
pling reaction with the carbapenem diphenylphosphates,
followed by deprotection of the resulting protected carbape-
nems in a usual manner.
The O-mesylated compound 1 was treated with sodium tri-
phenylmethylthioate, which was generated in situ from triphe-
nylmethyl mercaptan and sodium hydride in DMF, to provide
2 with inversion of the C-4 configuration. Compound 2 was
reduced with lithium borohydride in THF-EtOH and subse-
quently mesylated to give 4. The treatment of the mesylated
4 with sodium azide in DMSO gave the azide compound 5,
which was successfully converted into the amine 6 using tri-
phenylphosphine.
In this paper, we describe the synthesis and structure–activ-
ity relationships of 1β-methylcarbapenems having a 5′-cyclic
The amine 6 was converted to the isothiocyanate compound
7 by treatment of carbon disulfide and ethyl chloroformate.
Preparation of the thiourea type compounds (8) was accom-
plished by treatment of compound 7 with corresponding cyclic
amine (Scheme 1).
* Corresponding author.
E-mail address: choh@kist.re.kr (C.-H. Oh).
0223-5234/$ - see front matter © 2006 Elsevier SAS. All rights reserved.
doi:10.1016/j.ejmech.2006.02.006

826
T. Han et al. / European Journal of Medicinal Chemistry 41 (2006) 825–832
Scheme 1.
Scheme 2.
Carbamoylation of amine was carried out by a conventional
was defined as the lowest concentration that visibly inhibited
growth.
method using p-nitrophenyl chloroformate to give urea type
compounds (9) (Scheme 2). Deprotection of the trityl group
to mercaptans (I and II) were achieved by treatment of 8 and
9 with trifluoroacetic acid in the presence of triethylsilane.
Finally, the reaction of 10 [14] with thiols (I and II) in the
presence of diisopropylethylamine provided the 2-substituted
carbapenems (11). Deprotection of these compounds were car-
ried out by tetrakis(triphenylphosphine)palladium(0) and tribu-
tyltin hydride gave the crude products, which were purified by
HP-20 column to give the pure carbapenems (III and IV)
(Scheme 3).
The in vitro antibacterial activities of the new carbapenems
(IIIa–f and IVa–d) prepared above against Gram-positive and
negative bacteria are listed in Table 1. For comparison, the
MIC values of imipenem and meropenem are also listed. All
compounds displayed superior or similar antibacterial activities
against Gram-positive to meropenem, and against Gram-nega-
tive bacteria except Pseudomonas aeruginosa to imipenem.
As to the substituent on the pyrrolidine chain, the com-
pounds IIIa–f having cyclic thiourea moieties were generally
more potent than the cyclic urea compounds IVa–d. Compar-
ing the compounds IIIa–f having cyclic thiourea moieties
showed slight differences in the antibacterial activities against
Gram-positive and Gram-negative bacteria. As expected, the
piperazine thio compound IIId exhibited the most potent and
well-balanced activity. Furthermore we observed that the thio-
morpholine thiourea IIIa is more potent than the morpholine
IIIb. Introduction of sulfur atom significantly enhanced anti-
bacterial activity against Gram-negative bacteria compared to
that of oxygen atom (Table 2).
3. Biological activity
The MICs were determined by the agar dilution method
using test agar. An overnight culture of bacteria in tryptosoy
broth was diluted to about 106 cells per ml with the same broth
and inoculated with an inoculating device onto agar containing
serial twofold dilutions of the test compounds. Organisms were
incubated at 37 °C for 18–20 hours. The MICs of a compound

T. Han et al. / European Journal of Medicinal Chemistry 41 (2006) 825–832
827
Scheme 3.
Table 1
In vitro antibacterial activities of carbapenem derivatives (IIIa–f)
R=
IPMa
MPMb
Organism
IIIa
IIIb
0.01
0.05
0.05
0.03
0.05
0.05
3.10
0.10
0.10
0.05
1.67
IIIc
IIId
IIIe
0.01
0.03
0.05
0.05
0.05
0.05
6.20
0.10
0.10
0.10
1.54
IIIf
Streptococcus pyogenes. 308A < 0.01
< 0.01
< 0.01
0.03
0.03
0.05
0.05
1.50
0.10
0.05
0.05
2.31
< 0.01
< 0.01
0.03
0.01
0.05
0.05
0.40
0.10
0.05
0.05
1.85
<0.01
<0.01
0.03
0.03
0.05
0.03
1.50
0.05
0.05
0.03
1.98
<0.01
<0.01
0.01
0.01
0.40
0.10
0.80
0.80
0.10
0.20
0.12
0.01
0.01
0.05
0.05
0.03
0.03
0.40
0.05
0.03
0.03
1.00
Streptococcus pyogenes 77A
Streptococcus aureus SG 511
Streptococcus aureus 503
Escherichia coli DC O
Escherichia coli 1507 E
P. aeruginosa 9027
Salmonella typhimurium
Enterobacter cloacae P 99
Enterobacter cloacae 1321 E
DHP-I
0.03
0.01
0.01
0.05
0.03
3.10
0.03
0.05
0.01
2.37
MIC (µg ml–1) determined by agar dilution method.
a
IPM = imipenem.
MPM = meropenem.
b
Table 2
In vitro antibacterial activities of carbapenem derivatives (IVa–d)
R=
IPMa
MPMb
Organism
IVa
IVb
0.02
0.20
0.20
0.10
0.40
0.20
12.0
0.20
0.40
0.20
0.75
IVc
IVd
0.01
0.10
0.10
0.05
0.20
0.10
6.10
0.20
0.20
0.10
1.14
Streptococcus pyogenes 308A
Streptococcus pyogenes 77A
Streptococcus aureus SG 511
Streptococcus aureus 503
Escherichia coli DC O
Escherichia coli 1507 E
P. aeruginosa 9027
Salmonella typhimurium
Enterobacter cloacae P 99
Enterobacter cloacae 1321 E
DHP-I
0.01
0.10
0.10
0.10
0.20
0.10
6.10
0.20
0.20
0.10
0.80
0.01
0.05
0.10
0.05
0.20
0.10
3.10
0.10
0.20
0.10
1.23
<0.01
<0.01
0.01
0.01
0.40
0.10
0.80
0.80
0.10
0.20
0.18
0.01
0.01
0.05
0.05
0.03
0.03
0.40
0.05
0.03
0.03
1.00
MIC (µg ml–1) determined by agar dilution method.
a
IPM = imipenem.
MPM = meropenem.
b

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T. Han et al. / European Journal of Medicinal Chemistry 41 (2006) 825–832
Table 3
Comparative in vitro antibacterial activity of IIId, meropenem and imipenem against 40 strains (MIC, µg ml–1
)
Organism
IIId
0.03
0.03
0.01
0.01
<0.01
0.03
0.10
0.03
0.05
0.80
0.80
0.80
0.40
0.10
0.05
0.05
0.05
0.05
0.10
0.10
< 0.01
< 0.01
0.03
0.01
0.05
0.40
0.10
0.05
0.05
1.85
IPM
0.01
0.01
< 0.01
0.01
< 0.01
0.01
0.10
0.03
0.03
0.80
0.80
0.80
0.80
0.80
0.10
0.10
0.10
0.05
0.20
0.10
< 0.01
< 0.01
0.01
0.01
0.40
0.80
0.80
0.10
0.20
0.12
MPM
0.10
0.10
0.05
0.05
0.01
0.05
0.80
0.05
0.05
0.40
0.80
0.40
0.20
0.40
0.03
0.01
0.03
0.01
0.03
0.03
0.01
0.01
0.05
0.05
0.03
0.40
0.05
0.03
0.03
1.00
Organism
IIId
0.10
0.20
0.20
0.03
0.10
0.10
0.20
0.03
0.05
0.20
0.20
0.40
0.20
0.20
0.40
0.40
0.40
0.05
0.01
0.01
IPM
0.10
0.40
0.40
0.05
0.20
0.20
0.20
0.10
0.10
0.20
0.40
0.80
0.20
0.10
0.10
0.20
0.20
<0.01
0.01
< 0.01
MPM
0.03
0.05
0.05
0.01
0.10
0.03
0.05
0.01
0.01
0.05
0.05
0.20
0.10
0.10
0.10
0.10
0.05
0.05
0.05
0.03
Staphylococcus aureus giorgio
Staphylococcus aureus 209P
Staphylococcus aureus 503
Micrococcus luteus ATCC 9341
Streptococcus facium 77A
Streptococcus agalctiae B
Streptococcus durans D
Bacillus subtilts ATCC 6633
Bacillus megatherium
P. aeruginosa 9027
Salmonella paratyphi A
Salmonella typhimurium
Salmonella oranienberg
Salmonella typhi
Salmonella orion
Salmonella give
Klebsiella pneumonise 477
Enterobacter cloacae
Enterobacter cloacae 417
Serratia marcescens 370
Serratia marcescens 6093
Serratia marcescens 14273
Proteus mirabilis 112/3
Proteus mirabilis 174/3
Proteus vulgaris 868
Proteus rettgeri 936
P. aeruginosa 77/2
P. aeruginosa 110/2
P. aeruginosa 880/2
P. cepacia
Escherichia coli 086
Escherichia coli 0114
Escherichia coli 0126
Escherichia coli V6311/65
Escherichia coli TEM
Escherichia coli 1507
Streptococcus p. 308A
Streptococcus p. 77A
Streptococcus a. SG 511
Streptococcus a. 503
Escherichia coli DC O
Pseudomonas a. 9027
Salmonella typhimurium
Enterobacter cloacae P99
Enterobacter c.1321E
DHP-I
Proteus rettgeri 937
Pasteurella multocida
Corynebacterium diphtheriae
Corynebacterium pyogenes
The stability [13] to DHP-I of most compounds was tested
and all the compounds were more stable than meropenem. In
particular, the compounds IIIa and IIIc exhibited the most sta-
bility.
4.1. (2S,4S)-4-Tritylthio-1-(allyloxycarbonyl)pyrrolidine-2-
carboxylic acid methyl ester (2)
To a stirred solution of triphenylmethylthiol (80.0 g,
0.29 mol) in dry DMF (600 ml) was added dropwise sodium
hydride (11.6 g, 0.29 mol, 60% oil suspension) at 0 °C and was
stirred for 1 h at room temperature. To the resulting solution
was added 1 (76.7 g, 0.25 mol) solution in dry DMF (150 ml)
at 0 °C and was stirred for 3 h at room temperature. The reac-
tion mixture was poured into cold dilute HCl and extracted
with ethyl acetate. The organic layer was successively washed
with water and dried over anhydrous Na2SO4. Evaporation of
the solvent in vacuo gave a crude residue, which was purified
by silica gel column chromatography (EtOAc/n-hexane = 1:6)
to give 2 (100.6 g, 82.5%) as a pale yellow oil. 1H-NMR
(CDCl3) δ 1.75–1.85 (m, 1H), 2.01–2.20 (m, 1H), 2.85 (m,
1H), 3.16 (bs, 1H), 3.54 (bs, 1H), 3.77 and 3.80 (2s, 3H),
4.22 (m, 1H), 4.50–4.59 (bs, 2H), 5.20–5.31 (m, 2H), 5.84–
5.98 (m, 1H) 7.18–7.26 (m, 9H), 7.48 (d, 6H, J = 7.2).
The thiourea substituted compounds (IIIa–f) showed more
improved stability to DHP-I than the urea analogues (IVa–d).
Comparative in vitro activities of IIId, meropenem, and
imipenem against 40 bacterial strains were summarized in Ta-
ble 3. The selected carbapenem IIId possessed excellent in vi-
tro activity against 40 target pathogens except P. aeruginosa,
and superior or similar antibacterial activities against Gram-
positive to meropenem, and against Gram-negative bacteria to
imipenem. Against Pseudomonas cepacia, IIId was two to
four times more active than the compared meropenem and imi-
penem.
4. Experimental
Melting point (m.p.): Thomas Hoover apparatus, uncor-
rected. UV spectra: Hewlett Packard 8451A UV–VIS spectro-
photometer. IR spectra: Perkin Elmer 16F-PC FT-IR. NMR
spectra: Varian Gemini 300 spectrometer, tetramethylsilane
(TMS), as an internal standard. The mass spectrometry system
was based on a HP5989A MS Engine (Palo Alto, CA, USA)
mass spectrometer with a HP Model 59987A.
4.2. (2S,4S)-2-Hydroxymethyl-4-tritylthio-1-(allyloxycarbonyl)
pyrrolidine (3)
To a solution of 2 (107.3 g, 0.22 mol) in THF (800 ml) was
added slowly LiBH4 (4.79 g 0.22 mol) at 0 °C and was stirred
for 9 h at room temperature. The mixture was diluted with H2O

T. Han et al. / European Journal of Medicinal Chemistry 41 (2006) 825–832
829
(200 ml), 1 N-HCl (200 ml) and ethyl acetate (800 ml). The
organic layer was dried over anhydrous Na2SO4, concentrated,
and the resulting residue was purified by silica gel column
chromatography (EtOAc/n-hexane = 1:3) to give 3 (79.4 g,
NMR (CDCl3) δ 1.88 (m, 1H), 2.19 (m, 1H), 2.4–2,80 (d, 2H),
2.85–3.01 (m, 2H), 3.88 (m, 1H), 4.45–4.56 (m, 2H), 5.22–
5.30 (bs, 2H), 5.81–5.93 (m, 1H), 7.20–7.30 (m, 9H), 7.45
(d, 6H, J = 7.5).
1
78.5%) as a pale yellow oil. H-NMR (CDCl3) δ 1.58 (m,
1H), 1.98 (m, 1H), 2.75–2.89 (m, 2H), 3.01 (m, 1H), 3.55
(bs, 2H), 3.74 (m, 1H), 4.52 (bs, 2H), 5.23–5.30 (m, 2H),
5.80–5.88 (m, 1H), 7.20–7.27 (m, 9H), 7.47 (d, 6H, J = 7.5).
4.6. (2S,4S)-2-(2-Isothiocyanatomethyl-4-tritylthio-1-
(allyloxycarbonyl)pyrrolidine (7)
A solution of 6 (2.0 g, 4.4 mmol) and triethylamine
(0.66 ml, 4.8 mmol) in dry THF (20 ml) was cooled to 0 °C
under nitrogen and treated with carbon disulfide (0.30 ml,
4.8 mmol). The mixture was stirred at 0 °C for 1 h and was
dropwise ethyl chloroformate (0.45 ml, 4.80 mmol). The mix-
ture was stirred at room temperature for 1 h, and then diluted
with ethyl acetate (100 ml), and washed with 10% NaHCO3
and brine. The organic layer was dried over anhydrous
Na2SO4. Evaporation of the solvent in vacuo gave a crude re-
sidue, which was purified by silica gel column chromatography
(EtOAc/n-hexane = 1:4) to give 7 (2.0 g, 91.6%) as a pale yel-
4.3. (2S,4S)-2-Mesyloxymethyl-4-tritylthio-1-(allyloxycarbonyl)
pyrrolidine (4)
A solution of 3 (68.9 g, 0.15 mol) and triethylamine
(24.2 ml, 0.18 mol) in dry CH2Cl2 (400 ml) was cooled to
0 °C under nitrogen and treated with methanesulfonyl chloride
(20.6 g, 0.18 mol). The mixture was stirred at 0 °C for 1 h,
diluted with CH2Cl2 (200 ml), and washed with 10%
NaHCO3 and brine. The organic layer was dried over anhy-
drous Na2SO4. Evaporation of the solvent in vacuo gave a
crude residue, which was purified by silica gel column chro-
matography (EtOAc/n-hexane = 1:3) to give 4 (75.2 g, 93.2%)
1
low oil. H-NMR (CDCl3) δ 1.70–1.77 (m, 1H), 1.94 (m, 1H),
2.81 (m, 1H), 2.89–3.10 (bs, 2H), 3.51 (bs, 1H), 3.78 (bs, 1H),
3.90 (bs, 1H), 4.55–4.62 (m, 2H), 5.26–5.35 (m, 2H), 5.85–
5.97 (m, 1H), 7.21–7.34 (m, 9H), 7.50 (d, 6H, J = 7.2).
1
as a pale yellow oil. H-NMR (CDCl3) δ 1.81 (bs, 1H), 2.11
(bs, 1H), 2.75–2.82 (bs, 2H), 2.99 (bs, 4H), 3.95 (bs, 1H), 4.22
(bs, 1H), 4.40–4.50 (bs, 3H), 5.22-5.31 (bs, 2H), 5.80–5.91 (m,
1H), 7.20–7.31 (m, 9H), 7.48 (d, 6H, J = 7.7).
4.7. (2S,4S)-2-[2-(4-Thiomorpholinylthioureido)methyl]-4-
tritylthio-1-(allyloxycarbonyl)pyrrolidine (8a)
4.4. (2S,4S)-2-Azidomethyl-4-tritylthio-1-(allyloxycarbonyl)
pyrrolidine (5)
To a solution of 7 (1.0 g, 2.0 mmol) in MeOH (10 ml) was
added slowly thiomorpholine (0.41 g, 4.0 mmol) at room tem-
perature and was stirred for 2 h. The mixture was diluted with
H2O (30 ml) and ethyl acetate (50 ml). The organic layer was
dried over anhydrous Na2SO4, concentrated, and the resulting
residue was purified by silica gel column chromatography
(EtOAc/n-hexane = 1:1) to give 8a (0.98 g, 84.5%) as a pale
A mixture of 4 (28.5 g, 0.053 mol) and sodium azide
(13.8 g, 0.21 mol) in DMSO (300 ml) was heated at 70 °C
for 5 h. The reaction mixture was poured into ice water and
extracted with ethyl acetate (300 ml × 2). The organic layer
was successively washed with water (200 ml × 2), brine and
dried over anhydrous Na2SO4. Evaporation of the solvent in
vacuo gave a crude residue, which was purified by silica gel
column chromatography (EtOAc/n-hexane = 1:5) to give 5
(22.6 g, 85.4%) as a pale yellow oil. 1H-NMR (CDCl3) δ
1.92 (m, 1H), 2.15 (m, 1H), 2.77–2.82 (bs, 2H), 2.85–3.01
(m, 2H), 3.88 (m, 1H), 4.52–4.63 (bs, 3H), 5.29–5.38 (bs,
2H), 5.80–5.88 (m, 1H), 7.22–7.31 (m, 9H), 7.46 (d, 6H,
J = 7.5).
1
yellow oil. H-NMR (CDCl3) δ 1.54 (m, 1H), 2.12 (m, 1H),
2.43 (bs, 1H), 2.73–2.80 (bs, 4H), 2.83–2.90 (bs, 2H), 2.96–
3.17 (bs, 2H), 3.68–3.89 (bs, 1H), 3.85–4.15 (m, 4H), 4.45 (d,
2H, J = 5.5 Hz), 5.23–5.30 (m, 2H), 5.85–5.97 (m, 1H), 7.22–
7.32 (m, 9H), 7.46 (d, 6H, J = 7.5), 8.07 (bs, 1H).
The synthesis of compounds 8b–f were carried out by the
same procedure as described for the preparation of 8a using the
corresponding amines.
1
8b: Yield 85.5%. H-NMR (CDCl3) δ 1.64 (m, 1H), 2.12
4.5. (2S,4S)-2-(2-Aminomethyl-4-tritylthio-1-(allyloxycarbonyl)
pyrrolidine (6)
(m, 1H), 2.69–2.77 (m, 2H), 3.01 (bs, 1H), 3.30 (m, 1H), 3.66
(bs, 4H), 3.75 (bs, 4H), 3.89 (m, 2H), 4.44 (d, 2H, J = 5.2 Hz),
5.23–5.29 (m, 2H), 5.72–5.81 (m, 1H), 7.22–7.32 (m, 9H),
7.46 (d, 6H, J = 7.5), 8.13 (bs, 1H).
A mixture of 5 (9.0 g, 18.0 mmol), triphenylphosphine
(5.36 g, 20.0 mmol) and H2O (0.34 ml, 18.0 mmol) in THF
(30 ml) was heated at 40 °C for 4 h. After cooling, the reaction
mixture was diluted with H2O (30 ml) and ethyl acetate
(30 ml). The organic layer was successively washed with
water, brine and dried over anhydrous Na2SO4. Evaporation
of the solvent in vacuo gave a crude residue, which was pur-
ified by silica gel column chromatography (EtOAc/acet-
8c: Yield 83.0%.1H-NMR (CDCl3) δ 1.45–1.50 (bs, 3H),
1.75–1.85 (bs, 2H), 2.18 (m, 1H), 2.68–2.74 (bs, 2H), 2.92–
2.98 (bs, 2H), 3.29–3.40 (m, 3H), 3.82–3.90 (bs, 3H), 4.04–
4.20 (bs, 2H), 4.35 (d, 2H, J = 5.8), 5.17–5.24 (m, 2H), 5.86
(m, 1H), 7.22–7.32 (m, 9H), 7.46 (d, 6H, J = 7.5), 8.00 (bs,
1H).
1
8d: Yield 88.8%. H-NMR (CDCl3) δ 1.53 (m, 1H), 2.07
1
one = 2:1) to give 6 (7.29 g, 88.3%) as a pale yellow oil. H-
(m, 1H), 2.65–2.77 (bs, 2H), 3.02 (bs, 1H), 3.32 (bs, 1H),

830
T. Han et al. / European Journal of Medicinal Chemistry 41 (2006) 825–832
3.80–3.95 (bs, 8H), 4.46 (d, 2H, J = 5.8), 5.22–5.26 (bs, 2H),
5.90–5.96 (m, 1H), 7.18–7.31 (m, 9H), 7.46 (d, 6H, J = 7.0),
8.10 (bs, 1H).
4.9. Allyl (1R,5S,6S)-6-[(1R)-hydroxyethyl]-2-[5-
(thiomorpholinylthioureido)methyl]-1-(allyloxycarbonyl)
pyrrolidin-3-ylthio]-1-methylcarbapen-2-em-3-carboxylate
(11a)
1
8e: Yield 79.4%. H-NMR (CDCl3) δ 1.53 (m, 1H), 1.84–
1.95 (bs, 4H), 2.18 (m, 1H), 2.68–2.74 (bs, 2H), 2.97 (bs, 1H),
3.05 (bs, 1H), 3.54–3.69 (bs, 5H), 3.82 (bs, 1H), 4.48 (d, 2H,
J = 5.8), 5.25–5.34 (m, 2H), 5.86 (m, 1H), 7.22–7.32 (m, 9H),
7.46 (d, 6H, J = 7.3), 8.06 (bs, 1H).
To a solution of 8a (0.60 g, 1.0 mmol) in CH2Cl2 (2 ml)
was added dropwise triethylsilane (0.13 g, 1.1 mmol) at 5 °C,
and then TFA (2 ml). After stirring for 30 min at room tem-
perature, the mixture was evaporated under reduced pressure.
The residue was dissolved with ethyl acetate and washed with
10% NaHCO3, brine. The organic layer was concentrated in
vacuo to give a residue (Ia), which was used without further
purification. A solution of allyl (1R,5S,6S)-2-(diphenylpho-
sphoryloxy)-6-[(R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-
carboxylate (10, 0.50 g, 1.0 mmol) in CH3CN (10 ml) was
cooled to 0° C under N2. To this solution was added diisopro-
pylethyl amine (0.13 g, 1.0 mmol) and a solution of the mer-
capto compound Ia in CH3CN (5 ml). After stirring for 5 h, the
mixture was diluted with ethyl acetate, washed with 10%
NaHCO3, brine, and dried over anhydrous MgSO4. Evapora-
tion in vacuo gave a foam, which was purified by silica gel
chromatography (EtOAc/n-hexane = 2:1) to give 11a (0.38 g,
59.5%) as a yellow amorphous solid. 1H-NMR (CDCl3) δ 1.27
(d, 3H, J = 7.0 Hz), 1.37 (d, 3H, J = 6.2 Hz), 1.88–1.96 (bs,
2H), 2.19 (bs, 2H), 2.66–2.85 (bs, 4H), 3.10 (bs, 1H), 3.25–
3.36 (m, 2H), 3.49–3.59 (bs, 2H), 3.71–3.84 (bs, 4H), 3.95 (m,
1H), 4.10–4.23 (bs, 2H), 4.40–4.52 (bs, 2H), 4.85 (dd, 1H,
J = 5.2 and 5.6 Hz), 4.98 (dd, 1H, J = 5.2 and 5.6 Hz), 5.12–
5.50 (m, 4H), 5.69–6.01 (bs, 2H), 8.08 (s, 1H).
1
8f: Yield 79.4%. H-NMR (CDCl3) δ 1.42–1.50 (bs, 2H),
1.80–1.91 (bs, 3H), 2.10–2.21 (m, 1H), 2.68–2.74 (bs, 2H),
2.97 (bs, 1H), 3.15 (bs, 2H), 3.64–3.72 (bs, 5H), 3.82 (bs,
1H), 4.48 (d, 2H, J = 5.8), 5.25–5.34 (m, 2H), 5.82–5.89 (m,
1H), 7.22–7.32 (m, 9H), 7.46 (d, 6H, J = 7.5), 8.03 (bs, 1H).
4.8. (2S,4S)-2-[2-(Thiomorpholinylureido)methyl]-4-tritylthio-
1-(allyloxycarbonyl)pyrrolidine (9a)
To a solution of 6 (2.0 g, 4.4 mmol) and triethylamine
(1.34 ml, 9.6 mmol) in dry CH2Cl2 (30 ml) was added slowly
p-nitrophenyl chloroformate (1.0 g, 5.0 mmol) at 0 °C and was
stirred for 1 h at same temperature. The mixture was diluted
with H2O (30 ml), CH2Cl2 (50 ml) and washed with brine. The
organic layer was concentrated in vacuo to give a residue,
which was used without further purification. To the solution
of residue in ethanol (20 ml) was added thiomorpholine
(0.90 g, 8.7 mmol) and stirred for 1 h at room temperature.
The reaction mixture was neutralized with 3 N-HCl, diluted
with ethyl acetate (100 ml), and washed with brine. The organ-
ic layer was dried over anhydrous Na2SO4, which was purified
by silica gel column chromatography (EtOAc/n-hexane = 1:1)
to give 9a (1.4 g, 55.0%) as a pale yellow oil. 1H-NMR
(CDCl3) δ 1.57 (m, 1H), 2.17 (m, 1H), 2.53–2.57 (bs, 4H),
2.72–2.77 (bs, 2H), 2.95–3.10 (bs, 2H), 3.61 (m, 1H), 3.64–
3.69 (bs, 4H), 3.79 (m, 1H), 4.47 (d, 2H, J = 5.9 Hz), 5.21–
5.26 (d, 2H), 5.80–5.86 (m, 1H), 6.45 (bs, 1H), 7.18–7.32 (m,
9H), 7.46 (d, 6H, J = 7.5).
The synthesis of compounds 11b–f and 12a–d were carried
out by the same procedure as described for the preparation of
11a.
11b: Yield 61.4%. 1H-NMR (CDCl3) δ 1.24 (d, 3H,
J = 7.1 Hz), 1.33 (d, 3H, J = 6.4 Hz), 1.74 (bs, 1H), 2.02 (bs,
1H), 2.56 (m, 1H), 3.10–3.30 (bs, 2H), 3.49–3.59 (bs, 2H),
3.65–3.74 (bs, 4H), 3.81–3.90 (bs, 5H), 4.10–4.23 (bs, 2H),
4.40–4.52 (bs, 2H), 4.59 (dd, 1H, J = 5.2 and 5.6 Hz), 4.68
(dd, 1H, J = 5.2 and 5.6 Hz), 5.13–5.45 (m, 4H), 5.69–6.00
(bs, 2H), 8.09 (bs, 1H).
The compounds 9b–d were also prepared as described for
the preparation of 9a using the corresponding amines.
11c: Yield 49.8%. 1H-NMR (CDCl3) δ 1.24 (d, 3H,
J = 7.0 Hz), 1.34 (d, 3H, J = 6.1 Hz), 1.43–1.57 (bs, 2H),
1.60–1.98 (bs, 3H), 1.98 (m, 1H), 2.46 (bs, 1H), 3.23–3.39
(m, 2H), 3.49–3.69 (bs, 4H), 3.80–3.95 (m, 2H), 4.10–4.20
(bs, 5H), 4.40–4.52 (bs, 2H), 4.59 (dd, 1H, J = 5.1 and
5.5 Hz), 4.68 (dd, 1H, J = 5.1 and 5.5 Hz) , 5.20–5.49 (m,
4H), 5.89–6.00 (bs, 2H), 7.99 (bs, 1H).
11d: Yield 51.4%. 1H-NMR (CDCl3) δ 1.26 (d, 3H,
J = 7.0 Hz), 1.35 (d, 3H, J = 6.2 Hz), 1.68 (bs, 1H), 2.03 (bs,
1H), 2.80 (bs, 1H), 3.13 (bs, 1H), 3.35–3.46 (m, 3H), 3.59–
3.79 (bs, 10H), 3.95 (m, 1H), 4.18–4.23 (bs, 2H), 4.40–4.52
(bs, 2H), 4.55 (bs, 2H), 4.59 (m, 2H), 4.78 (m, 2H), 5.12–
5.50 (m, 6H), 5.65–6.01 (bs, 3H), 8.20 (bs, 1H).
1
9b: Yield 60.2%. H-NMR (CDCl3) δ 1.42 (bs, 1H), 2.05
(bs, 1H), 2.67 (bs, 1H), 2.97 (bs, 1H), 3.07 (bs, 2H), 3.24 (bs,
4H), 3.75 (bs, 5H), 3.82 (bs, 1H), 4.45 (bs, 2H), 5.25 (bs, 2H),
5.75–5.80 (m, 1H), 6.65 (bs, 1H), 7.13–7.22 (m, 9H), 7.40 (d,
6H, J = 7.5).
1
9c: Yield 58.8%. H-NMR (CDCl3) δ 1.45–1.52 (bs, 3H),
1.76–1.84 (bs, 2H), 2.11 (m, 1H), 2.68–2.77 (bs, 1H), 2.90–
2.95 (bs, 2H), 3.33–3.45 (bs, 2H), 3.82–3.94 (bs, 4H), 4.04–
4.10 (bs, 2H), 4.39 (bs, 2H), 5.25–5.32 (m, 2H), 6.55 (bs, 1H),
7.14–7.20 (m, 9H), 7.42 (d, 6H, J = 7.5).
1
9d: Yield 52.9%. H-NMR (CDCl3) δ 1.45 (m, 1H), 1.69–
11e: Yield 59.2%. 1H-NMR (CDCl3) δ 1.28 (d, 3H,
J = 7.0 Hz), 1.37 (d, 3H, J = 6.1 Hz), 1.43–1.52 (bs, 2H),
1.63–1.88 (bs, 3H), 1.98 (m, 1H), 2.46 (bs, 1H), 3.10 (bs,
1H), 3.20–3.44 (m, 3H), 3.49–3.69 (bs, 4H), 3.95–4.08 (m,
1.85 (bs, 4H), 2.12 (bs, 1H), 2.68–2.94 (bs, 4H), 3.29 (m, 1H),
3.75–3.82 (bs, 4H), 3.90 (bs, 1H), 4.45 (bs, 2H), 5.25–5.34 (m,
2H), 5.79–5.83 (m, 1H), 6.60 (bs, 1H), 7.14–7.20 (m, 9H),
7.42 (d, 6H, J = 7.8).

T. Han et al. / European Journal of Medicinal Chemistry 41 (2006) 825–832
831
1H), 4.11–4.23 (bs, 2H), 4.26–4.69 (bs, 6H), 5.13–5.49 (m,
4H), 5.76–5.98 (bs, 2H), 8.02 (bs, 1H).
1210 (C=S) cm−1. HRMS (FAB) Calcd. for C20H30N4O4S3
486.1429, Found 486.1428.
11f: Yield 58.3%. 1H-NMR (CDCl3) δ 1.22 (d, 3H,
J = 6.7 Hz), 1.30 (d, 3H, J = 6.2 Hz), 1.36–1.44 (bs, 2H),
1.76–2.03 (bs, 3H), 2.39 (bs, 1H), 3.11 (bs, 1H), 3.23–3.38
(m, 3H), 3.42–3.51 (bs, 3H), 3.80 (bs, 1H), 3.90–4.03 (m,
3H), 4.09–4.24 (bs, 2H), 4.40–4.76 (bs, 6H), 5.10–5.51 (m,
4H), 5.79–6.00 (bs, 2H)), 8.08 (bs, 1H).
12a: Yield 61.2%. 1H-NMR (CDCl3) δ 1.24 (d, 3H,
J = 7.0 Hz), 1.35 (d, 3H, J = 6.2 Hz), 1.78–1.86 (bs, 1H),
2.15 (bs, 2H), 2.60–2.70 (bs, 4H), 3.10–3.24 (bs, 2H), 3.49–
3.69 (bs, 6H), 3.95 (m, 1H), 4.10–4.23 (bs, 2H), 4.40–4.52 (bs,
2H), 4.55 (dd, 1H, J = 5.2 and 5.6 Hz), 4.66 (dd, 1H, J = 5.2
and 5.6 Hz), 5.12–5.50 (m, 4H), 5.81–6.01 (bs, 2H), 6.60 (bs,
1H).
12b: Yield 53.8%. 1H-NMR (CDCl3) δ 1.24 (d, 3H,
J = 7.1 Hz), 1.33 (d, 3H, J = 6.4 Hz), 1.74 (bs, 1H), 2.09 (bs,
1H), 2.56 (m, 1H), 3.10–3.27 (bs, 2H), 3.40–3.59 (bs, 3H),
3.65–3.79 (bs, 6H), 4.02–4.13 (bs, 2H), 4.20–4.32 (bs, 2H),
4.40–4.52 (bs, 2H), 4.59 (dd, 1H, J = 5.2 and 5.6 Hz), 4.68
(dd, 1H, J = 5.2 and 5.6 Hz), 5.13–5.49 (m, 4H), 5.79–5.97
(bs, 2H), 6.65 (bs, 1H).
12c: Yield 48.8%. 1H-NMR (CDCl3) δ 1.24 (d, 3H,
J = 7.0 Hz), 1.34 (d, 3H, J = 6.1 Hz), 1.43–1.59 (bs, 2H),
1.66–1.98 (bs, 3H), 2.04 (m, 1H), 2.46 (bs, 1H), 3.23–3.39
(m, 2H), 3.49–3.77 (bs, 5H), 3.80–3.95 (m, 2H), 4.10–4.26
(bs, 5H), 4.40–4.52 (bs, 2H), 4.59 (dd, 1H, J = 5.1 and
5.5 Hz), 4.68 (dd, 1H, J = 5.1 and 5.5 Hz), 5.20–5.49 (m,
4H), 5.89–6.00 (bs, 2H), 6.69 (bs, 1H).
The synthesis of compounds IIIb–f and IVa–d were carried
out by the same procedure as described for the preparation of
IIIa.
1
IIIb: Yield 22.6%. UV λmax: 298 nm. H-NMR (D2O) δ
1.05 (d, 3H, J = 7.1 Hz), 1.16 (d, 3H, J = 6.5 Hz), 1.68 (m,
1H), 2.45–2.59 (bs, 2H), 2.85–3.19 (bs, 2H), 3.29–3.48 (bs,
5H), 3.53–3.65 (bs, 2H), 3.70–3.85 (bs, 6H), 3.96–4.11 (m,
2H). IR (KBr): 3460, 1710, 1670, 1210 (C=S) cm−1. HRMS
(FAB) Calcd. for C20H30N4O5S2 470.1658, Found 470.1658.
1
IIIc: Yield 21.5%. UV λmax: 298 nm. H-NMR (D2O) δ
1.08 (d, 3H, J = 5.5 Hz), 1.15 (d, 3H, J = 6.7 Hz), 1.36–1.47
(bs, 2H), 1.69 (m, 1H), 1.76–1.97 (bs, 2H), 2.48–2.59 (m, 1H),
3.23–3.38 (bs, 4H), 3.53–3.65 (m, 2H), 3.76–3.96 (bs, 6H),
4.04–4.29 (bs, 3H). IR (KBr): 3430, 1720, 1710, 1210 (C=S)
cm−1. HRMS (FAB) Calcd. for C21H32N4O5S2 484.1814,
Found 484.1811.
1
IIId: Yield 21.2%. UV λmax: 298 nm. H-NMR (D2O) δ
1.01 (d, 3H, J = 7.0 Hz), 1.14 (d, 3H, J = 6.2 Hz), 1.40–1.57
(m, 1H), 2.45–2.56 (bs, 2H), 2.96–3.18 (bs, 5H), 3.21–3.44
(bs, 2H), 3.51–3.58 (bs, 2H), 3.64–3.88 (bs, 6H), 4.14 (bs,
2H). IR (KBr): 3400, 1720, 1670, 1220 (C=S) cm−1. HRMS
(FAB) Calcd. for C20H31N5O4S2 469.1817, Found 469.1820.
1
IIIe: Yield 18.6%. UV λmax: 298 nm. H-NMR (D2O) δ
1.10 (d, 3H, J = 6.9 Hz), 1.21 (d, 3H, J = 6.2 Hz), 1.77–1.86
(bs, 4H), 2.44 (m, 1H), 3.13–3.30 (bs, 5H), 3.34–3.45 (m, 2H),
3.54–3.69 (bs, 4H), 3.82 (bs, 1H), 3.95 (m, 1H), 4.16 (m, 2H).
IR (KBr): 3390, 1710, 1680, 1220 (C=S) cm−1. HRMS (FAB)
Calcd. for C20H30N4O4S2 454.1708, Found 454.1708.
12d: Yield 51.7%. 1H-NMR (CDCl3) δ 1.24 (d, 3H,
J = 7.0 Hz), 1.35 (d, 3H, J = 6.0 Hz), 1.45–1.58 (bs, 2H),
1.79–1.92 (bs, 3H), 1.98 (m, 1H), 2.46 (bs, 1H), 3.16–3.44
(bs, 4H), 3.49–3.71 (bs, 5H), 3.90–4.08 (m, 2H), 4.11–4.23
(bs, 2H), 4.26–4.69 (bs, 4H), 5.13–5.49 (m, 4H), 5.76–5.98
(bs, 2H), 6.61 (bs, 1H).
1
IIIf: Yield 16.0%. UV λmax: 298 nm. H-NMR (D2O) δ
1.03 (d, 3H, J = 6.4 Hz), 1.11 (d, 3H, J = 6.2 Hz), 1.33–1.46
(bs, 2H), 1.65–1.96 (bs, 3H), 2.46 (m, 1H), 3.05–3.26 (bs, 4H),
3.45–3.54 (bs, 2H), 3.60–3.78 (bs, 5H), 3.95–4.08 (bs, 2H),
4.18 (m, 2H). IR (KBr): 3490, 1720, 1680, 1190 (C=S) cm−1.
HRMS (FAB) Calcd. for C21H32N4O5S2 484.1814, Found
484.1812.
1
4.10. (1R,5S,6S)-6-[(1R)-Hydroxyethyl]-2-{5-[5-
(thiomorpholinylthioureido)methyl] pyrrolidin-3-ylthio}-1-
methylcarbapen-2-em-3-carboxylic acid (IIIa)
IVa: Yield 24.6%. UV λmax: 298 nm. H-NMR (D2O) δ
1.06 (d, 3H, J = 5.0 Hz), 1.13 (d, 3H, J = 6.2 Hz), 1.56 (m,
1H), 2.48–2.55 (m, 1H), 2.58–2.65 (bs, 5H), 2.85–3.01 (bs,
2H), 3.24–3.48 (bs, 5H), 3.53–3.65 (bs, 4H), 3.70–3.82 (bs,
1H), 4.11 (m, 1H). IR (KBr): 3480, 1710, 1690, 1660, 1210
(C=S) cm−1. HRMS (FAB) Calcd. for C20H30N4O5S2
470.1658, Found 470.1656.
To a stirred solution of 11a (0.42 g, 0.68 mol) and
Pd(PPh3)4 (60 mg) in CH2Cl2 (10 ml) was added dropwise n-
tributytin hydride (0.36 ml, 1.32 mmol) at 0 °C and was stirred
for 1 h at same temperature. To the resulting solution was di-
luted with water (20 ml) and the organic layers was washed
with water (2 × 220 ml). The combined aqueous layers were
washed with ethyl ether (2 × 20 ml) and lyophilized to give a
yellow powder which was purified on a Diaion HP-20 column,
eluting with 2% THF in water. Fractions having UV absorption
at 298 nm were collected and lyophilized again to give the title
1
IVb: Yield 29.2%. UV λmax: 298 nm. H-NMR (D2O) δ
1.07 (d, 3H, J = 6.9 Hz), 1.16 (d, 3H, J = 6.2 Hz), 1.55 (m,
1H), 2.45–2.55 (m, 1H), 3.21–3.42 (bs, 6H), 3.45–3.51 (bs,
2H), 3.55–3.69 (bs, 6H), 3.76–3.83 (m, 1H), 3.86–3.94 (m,
1H), 3.98–4.11 (m, 2H). IR (KBr): 3490, 1730, 1710, 1670,
1210 (C=S) cm−1. HRMS (FAB) Calcd. for C20H30N4O6S
454.1886, Found 454.1883.
1
compound IIIa as an amorphous solid. Yield 24.3%. UV λmax
:
IVc: Yield 21.0%. UV λmax: 298 nm. H-NMR (D2O) δ
1
298 nm. H-NMR (D2O) δ 1.01 (d, 3H, J = 5.3 Hz), 1.12 (d,
3H, J = 6.5 Hz), 1.58 (m, 1H), 2.48–2.57 (bs, 2H), 2.85–3.11
(bs, 5H), 3.24–3.48 (bs, 3H), 3.53–3.65 (bs, 2H), 3.70–3.90
(bs, 6H), 3.96–4.11 (m, 2H). IR (KBr): 3480, 1710, 1660,
1.08 (d, 3H, J = 5.5 Hz), 1.15 (d, 3H, J = 6.7 Hz), 1.38–1.49
(bs, 2H), 1.60 (m, 1H), 1.75–1.98 (bs, 2H), 2.48–2.59 (m, 1H),
3.23–3.38 (bs, 4H), 3.53–3.65 (m, 2H), 3.76–3.96 (bs, 6H),
4.04–4.20 (bs, 3H). IR (KBr): 3430, 1730, 1720, 1670, 1210

832
T. Han et al. / European Journal of Medicinal Chemistry 41 (2006) 825–832
(C=S) cm−1. HRMS (FAB) Calcd. for C21H32N4O6S 468.2043,
Found 468.2040.
[5] K. Inoue, Y. Hamana, T. Inoue, M. Fukasawa, M. Kato, Abstracts of
Papers of 34th Interscience Conference on Antimicrobial Agents Che-
motherapy, No. 1, Orlando, 1994.
1
IVd: Yield 23.2%. UV λmax: 298 nm. H-NMR (D2O) δ
[6] G. Bourboulis, P. Grecka, M. Grammatikou, H. Giamarellou, Abstracts
of Papers of 34th Interscience Conference on Antimicrobial Agents Che-
motherapy, No. 68, Orlando, 1994.
1.09 (d, 3H, J = 7.0 Hz), 1.19 (d, 3H, J = 6.2 Hz), 1.67 (m,
1H), 1.80 (bs, 4H), 2.45–2.56 (m, 1H), 3.09–3.18 (bs, 4H),
3.21–3.34 (bs, 2H), 3.45–3.58 (bs, 4H), 3.74–3.83 (bs, 1H),
3.85–3.98 (bs, 1H), 4.14 (bs, 2H). IR (KBr): 3480, 1720,
1700, 1670, 1220 (C=S) cm−1. HRMS (FAB) Calcd. for
C20H30N4O5S 438.1937, Found 438.1940.
[7] C.-H. Oh, J.-H. Cho, J. Antibiot 47 (1994) 126–128.
[8] C.B. Jin, I.S. Jung, H.-J. Ku, J.W. Yook, D.-H. Kim, J.-H. Cho, M.S.
Kim, C.-H. Oh, Toxicology 138 (1999) 59–67.
[9] C.-H. Oh, H.-W. Cho, I.-K. Lee, J.-Y. Gong, J.-H. Choi, J.-H. Cho,
Arch. Pharm. Med. Chem. 335 (2002) 152–158.
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