Synthesis and antibacterial activity of 1β-methyl-2-(5-substituted thiazolidinopyrrolidin-3-ylthio)carbapenems and related compounds

Article abstract of DOI:10.1002/1521-4184(200204)335:4<152::AID-ARDP152>3.0.CO;2-B

The synthesis of a new series of 1β-methylcarbapenems containing the substituted thiazolidinopyrrolidine moiety is described. Their in vitro antibacterial activities against both Gram-positive and Gram-negative bacteria were tested and the effect of substituent on the thiazolidine ring was investigated. A particular compound (18c) having a 2-amide substituted thiazolidine moiety showed the most potent antibacterial activity.

Full text of DOI:10.1002/1521-4184(200204)335:4<152::AID-ARDP152>3.0.CO;2-B

152 Oh et al.
Arch. Pharm. Pharm. Med. Chem. 2002, 4, 152–158
Chang-Hyun Oha),
Han-Won Choa),
In-Kyu Leea),
Jai-Yang Gongb),
Joung-Hoon Choic),
Jung-Hyuck Choa)
Synthesis and Antibacterial Activity of
1␤-Methyl-2-(5-substituted
thiazolidinopyrrolidin-3-ylthio)carbapenems and
Related Compounds
The synthesis of a new series of 1β-methylcarbapenems containing the substituted
thiazolidinopyrrolidine moiety is described. Their in vitro antibacterial activities
against both Gram-positive and Gram-negative bacteria were tested and the effect
of substituent on the thiazolidine ring was investigated.A particular compound (18c)
having a 2-amide substituted thiazolidine moiety showed the most potent anti-
bacterial activity.
a)
Medicinal Chemistry
Research Center,
Korea Institute of Science
and Technology, Seoul,
Korea
b)
Pharmaceutical Screening
Lab, Korea Research
Institute of Chemical
Keywords: Carbapenem; Antibiotics
Technology , Taejon, Korea
Department of Chemistry,
c)
Received: October 1, 2001 [FP637]
Hanyang University,
Seoul, Korea
Introduction
Chemistry
Imipenem [1], the first marketed carbapenem antibiotic,
is highly valued in the clinic for its efficacy against seri-
ous bacterial infections. However, due to its instability to
renal dehydropeptidase-I(DHP-I), it is used in combina-
tion with cilastatin, a DHP-I inhibitor. In 1984, it was re-
ported by Merck researchers [2] that the introduction of a
methyl group on the carbapenem nucleus resulted in a
great improvement of both the chemical and metabolic
stabilities.
Our general synthetic route leading to new carbapen-
ems involved the preparation of appropriately protected
thiols containing a thiazolidine ring as side chain and
their coupling reaction with the carbapenem diphenyl-
phosphates, followed by deprotection of the resulting
protected carbapenems in the usual manner.
2-Substituted thiazolidine derivatives (6a–e) were pre-
pared by the sequence shown in Scheme 1.Formation of
the 2-substituted thiazolidine ring was accomplished by
the reaction of the aldehydic compound 1 [10] with L-
cysteine ethyl ester in 60% aq EtOH solution.Thiazolid-
ine 2 was reduced with sodium borohydride in EtOH/
THF, and subsequently O-acetylation with acetic anhy-
dride was performed to give 4. Deprotection of the silyl
ether with TBAF gave the hydroxyl compound, which
was converted into the O-mesylated compound (5, 7, 9)
by treatment with mesyl chloride.Treatment of 5 with po-
tassium thioacetate in DMF followed by hydrolysis of the
resulting acetylthio group with 4N-NaOH in methanol
lead to the thiol compound (6a). Also, preparation of the
2-thiazinanecarboxylic acid (10) was carried out with
homocysteine using the same method as for the prepa-
ration of 2 and esterfication of 10 with EtOH in the pres-
ence of acid gave the ethyl 2-thiazinanecarboxlic ester
(11).
The carbapenem compounds which have a pyrrolidin-3-
ylthio group at the C-2 position in the carbapenem skele-
ton are noted for their broad and potent antibacterial ac-
tivity [3], and a large number of derivatives have been
synthesized and investigated [4–6]. Previously, we re-
ported the synthesis and biological properties of carbap-
enem compounds having the heterocyclic [7] and bicy-
clic moiety [8, 9].
As part of our program directed toward a new parenteral
1β-methylcarbapenem agent with improved properties
including antibacterial activity and stability to DHP-I, 1β-
methyl-2-(5-substituted
pyrrolidin-3-ylthio)carbapen-
ems, bearing 2-substituted thiazolidine or N-substituted
thiazolidine, were prepared.
The 2′-thiazolidinecarboxylic ester (2) was converted to
the amide (8) by aminolysis with aqueous ammonia in
MeOH. Preparation of thiols (6b–e) was carried out by a
method similar to that used for the preparation of 6a.
Correspondence: Jung-Hyuck Cho, Medicinal Chemistry
Research Center, Korea Institute of Science and Technology,
Seoul 130-650, Korea, Fax: +82 2 958 5189, e-mail:
choh@kist.re.kr.
© WILEY-VCH Verlag GmbH, 69451 Weinheim, 2002
0365-6233/04/0152 $ 17.50+.50/0

Arch. Pharm. Pharm. Med. Chem. 2002, 335, 152–158
New 1β-Methylcarbapenems 153
Scheme 1. (a) L-Cysteine ethyl ester, 60% ethanol, 0°C. (b) NaBH4, THF:EtOH = 4:6, 0°C. (c) (CH3CO)2O, Et3N,
CH2Cl2, 0°C. (d) TBAF, THF. (e) MsCl, Et3N, CH2Cl2. (f) AcSK, DMF:Toluene = 1:1, 70°C. (g) 4N NaOH, MeOH. (h)
NH4OH, MeOH, rt. (i) L-Homocysteine, 60% ethanol. (j) EtOH, H+.
Scheme 2. (k) L-Cysteine, 60% ethanol. 0°C. (l) BrCH2CH2SO2Cl, Et3N, CH2Cl2, 0°C. (m) cyclic amine, K2CO3, DMF,
90°C (n) RX, K2CO3, CH3CN, (o) ClSO2CH3, Et3N, CH2Cl2, 0°C.

154 Oh et al.
Arch. Pharm. Pharm. Med. Chem. 2002, 335, 152–158
Scheme 3. (p) Diisopropylethylamine, CH3CN, 0°C. (q) H2, Pd/C, THF:H2O = 1:1.
The N-alkylated and acylated thiazolidine thiol deriva-
tives (15a–g) were prepared as shown in Scheme 2.
Treatment of 12 with bromoethanesulfonyl chloride pro-
vided 13, which was reacted with cyclic amines to afford
corresponding compounds (14a–b). Also treatment of
12 with alkyl halides gave the corresponding N-alkylated
thiazolidine derivatives (14c–g). Other thiols (14a–g)
were prepared by a procedure similar to the preparation
of 6a.
positive and negative bacteria are listed in Table 1. For
comparision, the MIC values of Imipenem and Meropen-
em are also listed. Comparison of the compounds
(18a–c) having an amide, ester, or hydroxy group at the
2′ position of thiazolidine showed little difference in the
antibacterial activities against Gram-positive and Gram-
negative bacteria; however, the substituted thiazolidines
exhibited superior antibacterial activities to the non-sub-
stituted compound (20g). As expected, the 2-amide-
substituted compound (18c) showed the most potent
and well balanced activity. The ester-substituted com-
pound (18a) showed better antibacterial activity, espe-
cially against Gram-positive bacteria than the corre-
sponding analogues (18b–c, 20g).On the other hand, in
the N-alkylated thiazolidine series, the N-mesylated
compound (20f) showed the most potent activities
against Gram-positive and Gram-negative bacteria in-
cluding Pseudomonas aeruginosa. However, most N-
alkylated thiazolidine compounds (20a–e) displayed in-
ferior or similar antibacterial activities to the compound
20g, especially against Gram-positive bacteria includ-
Reaction of 16 [9] with thiol (6a–e, 15a–g) in the pres-
ence of diisopropylethylamine provided the 2-substitut-
ed carbapenem (18a–e, 20a–g) (Scheme 3). Deprotec-
tion of these compounds by catalytic hydrogenation
gave the crude products, which were purified on a HP-20
column to give the pure carbapenems.
Results and discussion
The in vitro antibacterial activities of the new carbapen-
ems (18a–e, 20a–g) prepared above against Gram-

Arch. Pharm. Pharm. Med. Chem. 2002, 335, 152–158
New 1β-Methylcarbapenems 155
Table 1. In vitro antibacterial activity(MIC, µg/mL) and DHP-1 stability of the carbapenem derivatives.
Strains
18a 18b 18c 18d 18e 20a 20b 20c 20d 20e 20f 20g Imi- Mero-
penem penem
1 Streptococcus pyogenes 308A
2 Streptococcus pyogenes 77A
3 Staphylococcus aureus SG511
4 Staphylococcus aureus 285
5 Escherichia coli DC2
<0.01 <0.01 0.01 <0.01 0.01 0.20 0.01 0.01 0.01 0.01 <0.01 0.01 <0.01 0.01
<0.01 <0.01 0.01 <0.01 0.01 0.10 0.01 0.01 0.01 0.01 <0.01 0.01 <0.01 <0.01
0.05 0.05 0.10 0.05 0.10 0.80 0.10 0.20 0.20 0.05 0.03 0.20 0.01 0.10
0.10 0.20 0.20 0.05 0.10 0.80 0.20 0.40 0.40 0.10 0.05 0.40 0.01 0.10
0.01 0.03 0.03 0.03 0.05 0.10 0.40 0.80 0.40 0.05 0.01 0.40 0.40 0.03
0.01 0.10 0.10 0.05 0.05 0.40 1.56 0.20 0.20 0.10 0.03 0.40 0.20 0.03
6 Escherichia coli TEM
7 Pseudemonas aeroginosa 1592E 1.56 12.5 0.80 6.10 1.56
25 100 25.0 50.0 1.56 3.10 6.25 0.80 0.20
8 Salmonella typhimurium
9 Klebsiella aerogenes 1522E
10 Enterobacter cloacae 132lE
DHP-1
0.20 0.10 0.05 0.80 0.05 0.40 0.20 0.40 0.40 0.20 0.03 0.40 0.80 0.03
0.05 0.20 0.05 0.10 0.05 0.80 3.10 0.40 0.40 0.20 0.03 0.40 0.10 0.05
0.01 0.05 0.01 0.05 0.02 0.20 0.80 0.20 0.20 0.05 0.03 0.20 0.10 0.03
10.80 11.14 13.80 13.17 14.43 11.91 13.9 11.01 11.50 9.40 9.81 10.30 1.84 9.13
ing Pseudomonas aeruginosa. Comparing the com-
pounds (18b, c, d, e) with 2-substituted thiazolidine or
2-substituted thiazinane moiety at C′-5 of pyrrolidine,
similar activity was observed against all tested bacteria.
Among these compounds, 18b, 18d, and 20f showed
superior or similar antibacterial activity against Gram-
positive bacteria to Meropenem, and 18c and 20f exhib-
ited improved antibacterial activity against Gram-nega-
tive bacteria compared to Imipenem, except in the case
of P.aeruginosa.As for DHP-I stability, most of the amide
substituted thiazolidine compounds, especially 18c and
18e, showed high stability to renal DHP-I.
monitored by the spectrophotometric method.One unit of activ-
ity was defined as the amount of enzyme hydrolyzing 1 µM of
glycyldehydrophenylalanine per min when the substrate,
50 µM, was incubated at 35 °C in 50 mM MOPS buffer, pH 7.0.
4-(tert-Butyldimethylsilanyloxy)-2-[(4-ethoxycarbonymethyl)-
thiazolidin-2-yl]-1-(p-nitrobenzyl oxycarbonyl)pyrrolidine (2)
To a solution of 1 (7.38 g, 18.0 mmol) in 90% aq. EtOH (50 mL)
was added slowly a solution of L-cysteine ethyl ester hydro-
chloride (3.34 g, 18.0 mmol) in water (20 mL) and NaHCO3
(1.52 g, 18.0 mmol) at –5°C. The reaction mixture was stirred
for 24 h at room temperature and then concentrated in vacuo to
give a white solid, which was diluted ethyl acetate and water.
Organic layers were dried over anhydrous Na2SO4, and the sol-
vent was removed in vacuo to give 2 as a light yellowish oil.Yield
77.3%.– 1H-NMR (CDCl3):δ (ppm) = 0.05 (s, 6H), 0.98 (s, 9H),
1.20 (t, 3H, J = 7.0 Hz), 2.01 (bs, 2H), 2.88 (m, 1H), 3.02–3.17
(bs, 4H), 3.25 (bs, 1H), 4.11 (q, 2H, J = 7.0 Hz), 4.23 (bs, 1H),
4.35 (bs, 1H), 5.06–5.19 (m, 2H), 7.46 (d, 2H, J = 7.2 Hz), 8.16
(d, 2H, J = 7.2 Hz). – IR (KBr) 3220 (NH), 1710, 1690 (C=O)
cm–1.
Experimental part
Melting point (mp): Thomas Hoover apparatus, uncorrected. –
UV spectra: Hewlett Packard 8451A UV-VIS spectrophotome-
ter. – 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-(tert-Butyldimethylsilanyloxy)-2-[(4-hydroxymethyl)thiazoli-
din-2-yl]-1-(p-nitrobenzyl oxycarbonyl)pyrrolidine (3)
To a solution of 2 (2.55 g, 4.80 mmol) in EtOH (50 mL) was add-
ed slowly NaBH4 (0.54 g 14.3 mmol) at 0°C. After 5 h, the mix-
ture was diluted with H2O (20 mL), 1N-HCl, and ethyl acetate
(50 mL).The organic layer was dried over anhydrous, concen-
trated Na2SO4 , and the resulting residue was purified by silica
gel column chromatography to give 3 as a pale yellow oil.Yield
67.3%.– 1H-NMR (CDCl3):δ (ppm) = 0.05 (s, 6H), 0.98 (s, 9H),
2.01 (bs, 2H), 2.88 (m, 1H), 3.02–3.17 (bs, 3H), 3.25–3.45 (m,
4H), 4.23 (bs, 1H), 4.35 (bs, 1H), 5.06–5.19 (m, 2H), 7.56 (d,
2H, J = 7.2 Hz), 8.12 (d, 2H, J = 7.2 Hz). – IR (KBr) 3318 (OH),
3220 (NH), 1690 (C=O) cm–1.
Measurement of in vitro antibacterial 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/mL with the same broth and inoc-
ulated with an inoculating device onto agar containing serial
twofold dilutions of the test compounds. Organisms were incu-
bated at 37°C for 18–20 hours. The MICs of a compound was
defined as the lowest concentration that visibly inhibited
growth.
Determination of susceptibility to renal dehydropeptidase-I
(DHP-I)
2-[(4-Acetoxymethyl)thiazolidin-2-yl]-4-(tert-butyldimethyl-
silanyloxy)-1-(p-nitrobenzyl oxycarbonyl)pyrrolidine (4)
The relative hydrolysis rate of carbapenems by porcine renal
DHP-I was determined, taking the initial hydrolysis rate of imi-
penem as 1.0. Partially purified porcine DHP-I (final concentra-
tion, 0.3 U/mL) was incubated with 50 µM carbapenem at 35°C
in 50 mM MOPS buffer. pH 7.0. The initial hydrolysis rate was
A solution of 3 (1.30 g, 2.71 mmol) and triethylamine (0.57 mL,
4.07 mmol) in dry CH2Cl2 was cooled to –5°C under nitrogen
and treated with acetic anhydride (0.38 mL, 4.07 mmol). The
mixture was stirred at 0°C for 1 h, diluted with ethyl acetate
(50 mL), and washed with cold water and brine. The organic

156 Oh et al.
Arch. Pharm. Pharm. Med. Chem. 2002, 335, 152–158
(m, 2H), 5.91 and 6.08 (2 s, 2H), 7.46 (d, 2H, J = 7.2 Hz), 8.16
(d, 2H, J = 7.2 Hz). – IR (KBr) 3230 (NH), 1705, 1670 (C=O)
cm–1
layer was dried over anhydrous Na2SO4, concentrated, and the
resulting residue was purified by silica gel column chromato-
grahy to give 4 as a pale yellow oil. Yield 95. %. – 1H-NMR
(CDCl3): δ (ppm) = 0.05 (s, 6 H), 1.98 (bs, 2H), 2.15 (s, 3H),
2.98 (m, 1H), 3.03–3.21 (bs, 3H), 3.25–3.45 (m, 4H), 4.21 (bs,
1H), 4.37 (bs, 1H), 5.06–5.13 (m, 2H), 7.50 (d, 2H, J = 7.2 Hz),
8.15 (d, 2H, J = 7.2 Hz).– IR (KBr) 3220 ( H), 1705, 1690 (C=O)
cm–1.
2-[4-(tert-Butyldimethylsilanyloxy)-1-(p-nitrobenzyloxycarbo-
nyl)pyrrolidin-2-yl]-[1,3]thiazinane-4-carboxylic acid ethyl ester
(11)
L-Homocysteine hydrochloride (0.71 g, 4.13 mmol) was dis-
solved in H2O (10 mL).NaOH (0.17 g, 4.13 mmol) in H2O (4 mL)
was added, followed by a solution of 2 (1.65 g, 4.13 mmol) in
EtOH (95%, 20 mL).The reaction mixture was stirred overnight
at room temperature and then concentrated in vacuo to give a
residue, which was diluted with ethyl acetate and water.Organ-
ic layers were dried over anhydrous Na2SO4, and the solvent
was removed in vacuo to give 10 as a light yellowish oil. This
material was used without further purification.To a stirred solu-
tion of 10 in EtOH (20 mL) was added three drops of sulfuric ac-
id. The reaction mixture was refluxed for 4 h and then was
cooled to 0°C.The mixture was neutralized with 10% NaHCO3 ,
diluted with ethyl acetate (50 mL) and H2O (20 mL), and
washed with brine.The organic layer was dried over anhydrous
Na2SO4. Removal of the solvent gave a crude residue, which
was purified by silica gel column chromatography to give 11 as
2-[(4-Acetoxymethyl)thiazolidin-2-yl]-4-methanesulfonyloxy-
1-(p-nitrobenzyloxycarbonyl)pyrrolidine (5)
To a solution of 4 (0.89 g, 1.66 mmol) inTHF (50 mL) was added
slowly a solution of 1 M tetrabutylammonium fluoride (2.49 mL,
2.49 mmol) in HF, and then was stirred for 2H at room tempera-
ture. The solvent was concentrated in vacuo to give a residue,
which was used without further purification. A solution of this
residue (0.67 g, 1.57 mmol) and triethylamine (0.23 mL,
1.73 mmol) in dry CH2Cl2 was cooled to –5°C under nitrogen
and treated with methanesulfonyl chloride (0.20 g, 1.73 mmol).
The mixture was stirred at 0°C for 1 h, diluted with ethyl acetate
(50 mL), and washed with cold water and brine.The organic lay-
er was dried over anhydrous Na2SO4. Evaporation of the sol-
vent in vacuo gave a crude residue, which was purified by silica
gel column chromatography to give 5 as a pale yellow oil.Yield
1
a pale yellow oil. Yield 75.6%. – H-NMR (CDCl3): δ (ppm) =
1
0.05 (s, 6H), 0.98 (s, 9H), 1.20 (t, 3H, J = 7.0 Hz), 1.68–1.85
(bs, 2H), 2.01 (bs, 2H), 2.78 (m, 1H), 3.02–3.17 (bs, 3H), 3.25
(bs, 2H), 4.11 (q, 2H, J = 7.0 Hz), 4.23 (bs, 1H), 4.35 (bs, 1H),
5.06–5.19 (m, 2H), 7.56 (d, 2H, J = 7.2 Hz), 8.14 (d, 2H, J = 7.2
Hz). – IR (KBr) 3250 (NH), 1720, 1680 (C=O) cm–1.
69.0%. – H-NMR (CDCl3): δ (ppm) = 1.98 (bs, 2H), 2.15 (s,
3H), 2.96 (m, 1H), 3.01 (s, 3H), 3.06–3.17 (bs, 3H), 3.25–3.45
(m, 4H), 4.21 (bs, 1H), 4.37 (bs, 1H), 5.06–5.13 (m, 2H), 7.54
(d, 2H, J = 6.9 Hz), 8.22 (d, 2H, J = 6.9 Hz). – IR (KBr) 3230
(NH), 1705, 1690 (C=O), 1220 (S=O) cm–1.
4-(tert-Butyldimethylsilanyloxy)-2-(thiazolidin-2-yl)-1-(p-nitro-
benzyloxycarbonyl)pyrrolidine (12)
2-(4-Hydroxymethylthiazolidin-2-yl)-4-mercapto-1-(p-nitro-
benzyloxycarbonyl)pyrrolidine (6a)
Synthesis of 12 from 1 was carried out by the same procedure
using aminoethane thiol as described for the preparation of 2.
Yield 87.2%.– 1H-NMR (CDCl3):δ (ppm) = 0.03 (s, 6H), 0.95 (s,
9H), 2.01 (bs, 2H), 2.88 (m, 1H), 3.02 (m, 1H), 3.14–3.30 (bs,
5H), 4.25 (bs, 1H), 4.35 (bs, 1H), 5.06 (q, 2H), 7.46 (d, 2H, J =
7.2 Hz), 8.13 (d, 2H, J = 7.2 Hz). – IR (KBr) 3250 (NH), 1680
(C=O) cm–1.
A mixture of 5 (0.58 g, 1.15 mmol) and potassium thioacetate
(0.39 g, 3.45 mmol) in DMF (20 mL) and toluene (20 mL) was
stirred at 70°C for 3 h under N2 gas. After cooling, the reaction
mixture was diluted with ethyl acetate (50 mL), water (50 mL),
and the aqueous layer was washed with ethyl acetate (20 mL
× 2). The combined solvent was washed with brine and dried
over anhydrous Na2SO4. Removal of the solvent gave a crude
residue, which was chromatographed on silica gel using ethyl
acetate/n-hexane (1:1) to give thioacetyl compound as a pale
yellow oil.To a solution of the above acetyl compound in MeOH
(15 mL) was added 0.58 mL of 4N-NaOH in an ice bath. After
stirring for 20 min, 0.58 mL of 4N-HCl was added to this solution
and the mixture diluted with ethyl acetate, washed with water,
brine and dried over anhydrous Na2SO4.The solvent was evap-
2-[3-(2-Chloroethanesulfonyl)thiazolidin-2-yl]-4-(tert-butyldi-
methylsilanyloxy)-1-(p-nitrobenzyloxycarbonyl)pyrrolidine (13)
A solution of 12 (2.27 g, 4.85 mmol) and triethylamine (0.81 mL,
5.82 mmol) in dry CH2Cl2 was cooled to –5°C under nitrogen
and treated with chloroethanesulfonyl chloride (0.61 mL,
5.82 mmol).The mixture was stirred at 0°C for 1 h, diluted with
ethyl acetate (50 mL), and washed with 10% NaHCO3 and
brine.The organic layer was dried over anhydrous Na2SO4.Re-
moval of the solvent gave a crude residue, which was purified
by silica gel column chromatography to give 13 as a pale yellow
oil.Yield 76.9%.– 1H-NMR (CDCl3):δ (ppm) = 0.05 (s, 6H), 0.94
(s, 9H), 1.98 (bs, 2H), 2.94 (m, 1H), 3.02 (m, 1H), 3.17–3.29
(bs, 5H), 3.45 (t, 2H, J = 5.8 Hz), 3.64 (t, 2H, J = 5.8 Hz), 4.23
(bs, 1H), 4.35 (bs, 1H), 5.06 (q, 2H), 7.55 (d, 2H, J = 6.9 Hz),
8.18 (d, 2H, J = 6.9 Hz). – IR (KBr) 1690 (C=O), 1220 (S=O)
cm–1.
1
orated in vacuo to give 6a as a yellow oil. Yield 78.9%. – H-
NMR (CDCl3):δ (ppm) = 2.05 (bs, 2H), 2.96 (m, 1H), 3.06–3.17
(bs, 3H), 3.25–3.45 (m, 4H), 4.21 (bs, 1H), 4.37 (bs, 1H),
5.06–5.13 (m, 2H), 7.41 (d, 2H, J = 6.9 Hz), 8.18 (d, 2H, J =
6.9 Hz). – IR (KBr) 3360 (OH), 3230 (NH), 2580 (SH), 1670
(C=O) cm–1.
Compounds 6b–e were prepared by a similar procedure to that
described for the preparation of 6a.
4-(tert-Butyldimethylsilanyloxy)-2-[(4-carbamoyl)thiazolidin-
2-yl]-1-(p-nitrobenzyloxycarbonyl)pyrrolidine (8)
4-(tert-Butyldimethylsilanyloxy)-2-[3-(2-thiomorpholin-4-yl-
ethanesulfonyl)thiazolidin-2-yl]-1-(p-nitrobenzyloxycarbonyl)-
pyrrolidine (14a)
To a stirred solution of 2 (1.50 g, 2.78 mmol) in MeOH (20 mL)
was added ammonium hydroxide (28%, 20 mL) and was stirred
for 20 h at room temperature.The mixture was neutralized with
6N-HCl, diluted with ethyl acetate (50 mL), and washed with
brine.The organic layer was dried over anhydrous Na2SO4, and
was purified by silica gel column chromatography to give 8 as a
pale yellow oil. Yield 87.1%. – 1H-NMR (CDCl3): δ = 0.05
(s, 6H), 0.98 (s, 9H), 2.01 (bs, 2H), 2.99 (m, 1H), 3.02–3.17
(bs, 2H), 3.25 (bs, 1H), 4.23 (bs, 1H), 4.35 (bs, 1H), 5.06–5.19
Compound 13 (1.11 g, 1.87 mmol), potassium carbonate
(0.28 g, 2.05 mmol), and thiomorpholine (0.21 g, 2.05 mmol)
were dissolved in DMF (20 mL) and the solution was heated at
90°C for 10 h.The resulting solution was diluted with ethyl ace-
tate. The organic layer was washed with water, 1N-HCl and
brine.Evaporation of the solvent in vacuo gave a crude residue,

Arch. Pharm. Pharm. Med. Chem. 2002, 335, 152–158
New 1β-Methylcarbapenems 157
(1R,5S,6S)-6-[(1R)-Hydroxyethyl)]-3-[5-(4-hydroxymethylthi-
azolidin-2-yl)pyrrolidin-3-ylthio]-1-methyl-1-carbapen-2-em-3-
carboxylic acid (18a)
which was chromatographed on silica gel using ethyl acetate/
hexane (1:1) as eluent to give 14a as a pale yellow oil. Yield
80.1%.– 1H-NMR (CDCl3):δ (ppm) = 0.01 (s, 6H), 0.95 (s, 9H),
1.98 (bs, 2H), 2.94 (m, 1H), 3.02–3.31 (bs, 8H), 3.40–3.62 (bs,
8H), 3.68 (t, 2H, J = 5.8 Hz), 4.23 (bs, 1H), 4.35 (bs, 1H), 5.01
(q, 2H), 7.42 (d, 2H, J = 7.2 Hz), 8.11 (d, 2H, J = 7.2 Hz).
Compound 17a (0.24 g, 0.06 mmol) and 0.1 g of Pd/C (10%)
were dissolved in THF/phosphate buffer (pH = 7) (1:1, 10 mL
each). The mixture was hydrogenated at 345 kPa for 1 h. The
solution was filtered through celite and washed with water (2 ×
10 mL).The combined filtrate was washed with ethyl ether (2 ×
20 mL) and lyophilized to give a yellow powder which was puri-
fied on reversed phase column chromatography, eluting with
5% THF in water. Fractions having UV absorption at 298 nm
were collected and lyophilized again to give the title compound
18a as a white powder.Yield 47.9%. – UV λmax : 298 nm. – Mp
145–150°C (dec.). – 1H-NMR (D2O): δ (ppm) = 1.06 (d, 3H, J =
6.5 Hz), 1.15 (d, 3H, J = 5.7 Hz), 1.56 (bs, 1H), 2.04 (bs, 1H),
2.46 (m, 1H), 3.05 (bs, 2H), 3.23 (bs, 2H), 3.40 (bs, 2H), 3.56
(bs, 2H), 3.77 (m, 2H), 4.10 (m, 2H), 4.39 (bs, 1H). – IR (KBr):
3470 (OH), 3230 (NH), 1710, 1690 (C=O) cm–1. – FABMS: m/z
430 (M + H)+.
Compounds 14b from 13 were prepared by the same proce-
dure as described for the preparation of 14a.
4-(tert-Butyldimethylsilanyloxy)-2-(3-methylthiazolidin-2-yl)-
1-(p-nitrobenzyloxycarbonyl)pyrrolidine (14c)
To a solution of potassium carbonate (0.54 g, 3.96 mmol) in dry
CH3CN (50 mL) was added slowly a solution of 12 (1.85 g, 3.96
mmol) in dry CH3CN (10 mL) under N2 gas. After 1 h, methyl
iodide (2.81 g, 19.8 mmol) was added dropwise to the reaction
mixture, which was stirred for 24 h at room temperature.The re-
sulting mixture was diluted with ethyl acetate (50 mL). The or-
ganic layer was washed with brine and dried over anhydrous
Na2SO4. Removal of the solvent gave a crude residue, which
was chromatographed on silica gel using ethyl acetate as elu-
1
18b:Yield 42.3%.– UV λmax:297 nm.– Mp 139–144°C (dec.).–
1H-NMR (D2O):δ (ppm) = 1.06 (d, 3H, J = 6.5 Hz), 1.15 (d, 3H, J
= 5.7 Hz), 1.23 (t, 3H, J = 7.0 Hz), 1.66 (bs, 1H), 2.04 (bs, 1H),
2.46 (m, 1H), 3.05 (bs, 2H), 3.23 (bs, 2H), 3.40 (bs, 2H), 3.77
(m, 2H), 4.10 (m, 2H), 4.11 (q, 2H, J = 7.0 Hz), 4.39 (bs, 1H). –
IR (KBr): 3450 (OH), 3250 (NH), 1720, 1705 (C=O) cm–1. –
FABMS: m/z 472 (M + H)+.
ent to give 14c as a pale yellow oil. Yield 82.0%. – H-NMR
(CDCl3): δ (ppm) = 0.05 (s, 6H), 0.98 (s, 9H), 2.06 (bs, 2H),
1
2.99 (m, 1H), 3.13–3.25 (bs, 6H), 3.30 (s, 3H), 4.24 (bs, H),
4.54 (bs, 1H), 5.11 (q, 2H), 7.46 (d, 2H, J = 7.2 Hz), 8.13 (d, 2H,
J = 7.2 Hz).
4-(tert-Butyldimethylsilanyloxy)-2-(3-methanesulfonylthiazoli-
din-2-yl)-1-(p-nitrobenzyloxycarbonyl)pyrrolidine (14g)
18c:Yield 34.6%.– UV λmax:298 nm.– Mp 172–180°C (dec.).–
1H-NMR (D2O):δ (ppm) = 1.09 (d, 3H, J = 6.3 Hz), 1.16 (d, 3H, J
= 5.9 Hz), 1.70 (bs, 1H), 2.04 (bs, 1H), 2.55 (m, 1H), 3.05 (bs,
2H), 3.23 (bs, 2H), 3.40 (bs, 2H), 3.77 (m, 2H), 4.10 (m, 2H),
4.39 (bs, 1H). – IR (KBr): 3450 (OH), 3240 (NH), 1690, 1660
(C=O) cm–1. – FABMS: m/z 443 (M + H)+.
A solution of 12 (0.73 g, 1.57 mmol) and triethylamine (0.23 mL,
1.73 mmol) in dry CH2Cl2 was cooled to 0°C under nitrogen and
treated with methanesulfonyl chloride (0.20 g, 1.73 mmol).The
mixture was stirred at 0°C for 1 h, diluted with ethyl acetate
(50 mL), and washed with cold water and brine. The organic
layer was dried over anhydrous Na2SO4.Evaporation of the sol-
vent in vacuo gave a crude residue, which was purified by silica
gel column chromatography to give 14g as a pale yellow oil.
Yield 89.0%.– 1H-NMR (CDCl3):δ (ppm) = 0.01 (s, 6H), 0.98 (s,
9H), 2.05 (bs, 2H), 2.82 (m, 1H), 3.05 (s, 3H), 3.22 (m, 1H),
3.14–3.30 (bs, 5H), 4.25 (bs, 1H), 4.35 (bs, 1H), 5.06–5.11 (q,
2H), 7.43 (d, 2H, J = 7.1 Hz), 8.13 (d, 2H, J = 7.1 Hz).– IR (KBr)
3250 (NH), 1680 (C=O), 1225 (S=O) cm–1.
18d:Yield 36.9%.– UV λmax:297 nm.– Mp 125–130°C (dec.).–
1H-NMR (D2O):δ (ppm) = 1.06 (d, 3H, J = 6.5 Hz), 1.15 (d, 3H, J
= 5.7 Hz), 1.23 (t, 3H, J = 7.0 Hz), 1.66–1.78 (bs, 3H), 2.02 (bs,
1H), 2.56 (m, 1H), 3.05 (bs, 2H), 3.23 (bs, 2H), 3.40 (bs, 2H),
3.77 (m, 2H), 4.10–4.16 (m, 4H), 4.39 (bs, 1H). – IR (KBr):
3480 (OH), 3210 (NH), 1705, 1690 (C=O) cm–1. – FABMS: m/z
472 (M + H)+.
18e:Yield 27.3%.– UV λmax:298 nm.– Mp 189–192°C (dec.).–
1H–NMR (D2O): δ (ppm) = 1.11 (d, 3H, J = 6.2 Hz), 1.21 (d, 3H,
J = 5.8 Hz), 1.59–1.78 (bs, 3H), 2.01 (bs, 1H), 2.78 (m, 1H),
3.05 (bs, 2H), 3.23 (bs, 2H), 3.42 (bs, 2H), 3.87 (m, 2H), 4.12
(m, 2H), 4.34 (bs, 1H).– IR (KBr):3430 (OH), 3250 (NH), 1685,
1665 (C=O) cm–1. – FABMS: m/z 457 (M + H)+.
Compounds 15b–f from 14b–f were carried out by the same
procedure as described for the preparation of 6a.
p-Nitrobenzyl(1R,5S,6S)-6-[(1R)-hydroxyethyl)]-2-[5-(4-hy-
droxymethylthiazolidin-2-yl)-1-(p-nitrobenzyloxycarbonyl)-
pyrrolidin-3-ylthio]-1-methyl-1-carbapen-2-em-3-carboxylate
(17a)
20a:Yield 66.0%. – UV λmax: 296 nm. – 1H-NMR (D2O): δ (ppm)
= 1.13 (d, 3H, J = 6.2 Hz), 1.21 (d, 3H, J = 5.8 Hz), 1.59 (bs,
1H), 2.01 (bs, 1H), 2.78–3.05 (m, 6H), 3.15 (bs, 2H), 3.23–
3.35 (bs, 6H), 3.42–3.66 (bs, 6H), 3.87 (m, 2H), 4.11 (m, 2H),
4.39 (bs, 1H). – IR (KBr): 3510 (OH), 3300 (NH), 1690 (C=O)
cm–1. – FABMS: m/z 529 (M + H)+.
A solution of p-nitrobenzyl-(1R,5S,6S)-3-(diphenylphosphoryl-
oxy)-6-[(R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carb-
oxylate (16, 0.54 g, 0.91 mmol) in CH3CN (50 mL) was cooled
to 0°C under N2. To this solution was added diisopropyl ethyl-
amine (0.13 g, 1.0 mmol) and a solution of the mercapto com-
pound 6a (0.36 g, 0.91 mmol) in CH3CN (10 mL). After stirring
for 2 h, the mixture was diluted with ethyl acetate, washed with
10% NaHCO3, brine, and dried over MgSO4. Evaporation in
vacuo gave a foam, which was purified by silica gel chromatog-
20b: Yield 35.0%. – UV λmax: 298, 310 nm. – Mp 145–151°C
(dec.).– 1H-NMR (D2O):δ (ppm) = 1.13 (d, 3H, J = 6.2 Hz), 1.21
(d, 3H, J = 5.8 Hz), 1.59 (bs, 1H), 2.21 (bs, 1H), 2.78–3.05 (m,
2H), 3.15 (bs, 2H), 3.24–3.55 (bs, 10H), 3.42–3.66 (bs, 6H),
1
raphy to give 17a as a yellow foam solid. Yield 79.3%. – H-
1
3.87 (m, 2H), 4.05 (m, 2H), 4.49 (bs, 1H), 7.31 (t, H, J = 6.4
NMR (CDCl3): δ (ppm) = 1.25 (d, 3H, J = 6.6 Hz), 1.33 (d, 3H, J
= 6.2 Hz), 1.88 (bs, 1H), 2.14 (m, 1H), 2.46 (m, 1H), 2.95 (m,
2H), 3.33 (bs, 2H), 3.45 (d, 2H, J = 9.6 Hz), 3.87 (m, 2H) 4.01–
4.18 (m, 3H), 4.25–4.35 (m, 2H), 4.43 (bs, 1H), 5.11–5.55 (m,
4H), 7.21 (d, 2H, J = 7.4 Hz), 7.41 (d, 2H, J = 7.4 Hz), 8.18 (d,
4H, J = 7.4 Hz). – IR (KBr): 3410 (OH), 3230 (NH), 1720, 1705,
1660 (C=O) cm–1.
Hz), 8.68 (d, 2H, J = 6.4 Hz). – IR (KBr): 3510 (OH), 3300 (NH),
2990, 1690 (C=O) cm–1. – FABMS: m/z 590 (M + H)+.
20c:Yield 41.2%.– UV λmax:298 nm.– Mp 115–123°C (dec.).–
1H-NMR (D2O):δ (ppm) = 1.11 (d, 3H, J = 6.2 Hz), 1.18 (d, 3H, J
= 5.9 Hz), 1.59 (bs, 1H), 2.03 (bs, 1H), 2.84 (m, 1H), 3.05 (bs,
2H), 3.23–3.42 (bs, 5H), 3.55 (s, 3H), 3.77 (m, 2H), 4.12 (m,

158 Oh et al.
Arch. Pharm. Pharm. Med. Chem. 2002, 335, 152–158
2H), 4.45 (bs, 1H). – IR (KBr): 3480 (OH), 3260 (NH), 1670
References
(C=O) cm–1. – FABMS: m/z 414 (M + H)+.
[1] W. J. Leanza, K. J. Wildonger, T. W. Miller, B. G. Chris-
20d:Yield 37.9%.– UV λmax:298 nm.– Mp 132–142°C (dec.).–
1H-NMR (D2O):δ (ppm) = 0.96 (d, 6H, J = 7.6 Hz), 1.16 (d, 3H, J
= 6.2 Hz), 1.30 (d, 3H, J = 5.9 Hz), 1.69 (bs, 1H), 2.03 (bs, 1H),
2.94 (m, 1H), 3.05 (bs, 2H), 3.22–3.51 (bs, 5H), 3.77 (m, 2H),
4.13 (m, 2H), 4.28 (m, 1H), 4.51 (bs, 1H). – IR (KBr): 3440
(OH), 3270 (NH), 1665 (C=O) cm–1. – FABMS: m/z 442
(M + H)+.
tensen, J. Med. Chem. 1979, 22, 1435–1436
[2] D.H.Shih, F.Baker, L.Cama, B.G.Christensen, Heterocy-
cles 1984, 21, 29–40.
[3] G. Albers-Schonberg, B. H. Arison, O. D. Hensens, J.
Hirshfield, K. Hoogstein, B. G. Christensen, J. Am. Chem.
Soc. 1978, 100, 6491–6499.
20e:Yield 34.5%.– UV λmax:296 nm.– Mp 133–134°C (dec.).–
1H-NMR (D2O):δ (ppm) = 1.16 (d, 3H, J = 6.9 Hz), 1.28 (d, 3H, J
= 5.4 Hz), 1.58 (bs, 1H), 2.01 (bs, 1H), 2.79 (m, 1H), 3.03 (bs,
2H), 3.22–3.59 (bs, 9H), 3.77 (m, 2H), 4.13 (m, 2H), 4.44 (bs,
1H). – IR (KBr): 3510 (OH), 3300 (NH), 1690 (C=O) cm–1. –
FABMS: m/z 444 (M + H)+.
[4] R. W. Ratcliffe, G. Albers-Schonberg, Academic Press,
New York, 1982, 2, 227–313.
[5] R. Wise, Antimicrobial Agents Chemother. 1986, 30,
343–349.
[6] D. Livingstone, M. J. Gill, R. Wise, J. Antimicrob. Chemo-
ther. 1995, 35, 1–5.
20f:Yield 40.1%. – UV λmax: 298 nm. – 1H-NMR (D2O): δ (ppm)
= 1.13 (d, 3H, J = 6.2 Hz), 1.19 (d, 3H, J = 5.9 Hz), 1.59 (bs,
1H), 2.03 (bs, 1H), 2.88 (m, 1H), 2.99 (s, 3H), 3.08 (bs, 2H),
3.23–3.42 (bs, 5H), 3.77 (m, 2H), 4.12 (m, 2H), 4.45 (bs, 1H).–
IR (KBr):3510 (OH), 3230 (NH), 1690 (C=O), 1220 (S=O) cm–1.
– FABMS: m/z 478 (M + H)+.
[7] C.-H. Oh, H. J. Kim, J.-H. Cho, Arch. Pharm. (Weinheim).
1995, 328, 385–387.
[8] K.-H. Nam, C.-H. Oh, J. K. Cho, K.-S. Lee, J.-H. Cho, Arch.
Pharm. Pharm. Med. Chem. 1996, 329, 443–446.
20g:Yield 34.7%.– UV λmax:298 nm.– Mp 111–115°C (dec.).–
1H-NMR (D2O):δ (ppm) = 1.13 (d, 3H, J = 6.2 Hz), 1.19 (d, 3H, J
= 5.9 Hz), 1.59 (bs, 1H), 2.03 (bs, 1H), 2.88 (m, 1H), 3.08 (bs,
2H), 3.18 (m, 2H), 3.30–3.55 (bs, 3H), 3.77 (m, 2H), 4.12 (m,
2H), 4.41 (bs, 1H). – IR (KBr): 3510 (OH), 3350 (NH), 1680
(C=O) cm–1. – FABMS: m/z 400 (M + H)+.
[9] K.-H.Nam, C.-H.Oh,Y.H.Ham, K.-S.Lee, J.-H.Cho, Arch.
Pharm. Pharm. Med. Chem. 1997, 330, 268–270.
[10] N. Ohtake, K.Yamada, O. Okamoto, S. Nakayama, J. Anti-
biotics. 1997, 50, 567–585.