Practical Large-Scale Synthesis of Doripenem: A Novel 1β- Methylcarbapenem Antibiotic

Article abstract of DOI:10.1021/op034088n

A practical large-scale process for the synthesis of doripenem hydrate (1), a novel parenteral 1β-methylcarbapenem antibiotic, from p-nitrobenzyl-protected enolphosphate 2b and N-(p-nitrobenzyloxycarbonyl)- protected aminomethylpyrrolidine 3c is described. We found effective extraction conditions to remove p-toluidine and most other organic impurities using a THF/ water system containing an inorganic salt. Significant improvements have been made to the previous synthesis using a medicinal chemical procedure. The new process requires no chromatographic purification and affords the target compound 1 as a sterile crystalline powder. Several kilograms of compound 1 were successfully prepared by this process.

Full text of DOI:10.1021/op034088n

Organic Process Research & Development 2003, 7, 846−850
Practical Large-Scale Synthesis of Doripenem: A Novel 1â-Methylcarbapenem
Antibiotic
Yutaka Nishino,† Makoto Kobayashi, Taneyoshi Shinno, Kenji Izumi, Hiroshi Yonezawa,‡ Yoshiyuki Masui,* and
Masayuki Takahira§
Bulk Chemicals Process R&D Department, Manufacturing Technology R&D Laboratories, Shionogi & Co., Ltd.,
Kuise Terajima 2-chome, Amagasaki, Hyogo 660-0813, Japan
Abstract:
is a novel parenteral 1â-methylcarbapenem antibiotic.8 In
our previous reports,8,9 its synthesis, biology, and structure-
activity relationships (SAR) have been reported. Compound
1 exhibits potent, broad, and well-balanced antibacterial
activity against a wide range of both Gram-positive and
Gram-negative bacteria including Pseudomonas aeruginosa.
According to the conventional retrosynthetic analysis of
a carbapenem, doripenem can be assembled from enolphos-
phate 2 and the 2-aminomethylpyrrolidin-4-ylthio-containing
side chain 3 (Scheme 1). In the medicinal chemical route
(Scheme 2),8,9 compound 1 was prepared by deprotection of
compound 5a or 5b with AlCl3-anisole.10 Compound 5a or
5b was synthesized from the diphenylmethyl-protected
enolphosphate 2a and N-p-methoxybenzyl()PMZ)-protected
aminomethylpyrrolidine 3a or N-BOC-protected amino-
methylpyrrolidine 3b, respectively. Although this route
facilitated the SAR studies and led to rapid optimization of
lead derivatives, it had several drawbacks for a multikilo-
gram-scale preparation of compound 1. The two most serious
problems resided in the isolation in the deprotection step.
Compound 1 was isolated as a foam. The original route
required chromatographic purification on Diaion HP-20. In
the first-generation process (Scheme 3), we succeeded in
obtaining compound 1 as a crystalline monohydrate. How-
ever, the process still required chromatographic purification,
and the yield (49%) of compound 1 from compound 5b
through the deprotection, purification, and crystallization
steps on a pilot scale was lower than that (72%) through the
deprotection and purification step on a bench scale. We
investigated the reason for this as follows: The step yields
of the deprotection reaction were the same on bench and
pilot scales. The yield of crystallization including sterilization
on pilot scale was 88%. However, the yields of purified
compound 1 before crystallization on bench and pilot scales
were 72 and 56%, respectively. During chromatography and
concentration of the eluents, decomposition of the target
comound 1 was observed, resulting in a 16% yield decrease
due to longer operating times on scale-up. To increase the
yield and to avoid the chromatographic purification, we then
developed an improved process which requires no chro-
matographic purification. In this contribution,11a we describe
A practical large-scale process for the synthesis of doripenem
hydrate (1), a novel parenteral 1â-methylcarbapenem antibiotic,
from p-nitrobenzyl-protected enolphosphate 2b and N-(p-
nitrobenzyloxycarbonyl)-protected aminomethylpyrrolidine 3c
is described. We found effective extraction conditions to remove
p-toluidine and most other organic impurities using a THF/
water system containing an inorganic salt. Significant improve-
ments have been made to the previous synthesis using a
medicinal chemical procedure. The new process requires no
chromatographic purification and affords the target compound
1 as a sterile crystalline powder. Several kilograms of compound
1 were successfully prepared by this process.
Introduction
Carbapenem compounds are noted for their broad and
potent antibacterial activity.1 Imipenem,2 panipenem,3 mero-
penem,4 biapenem5 and ertapenem6 are marketed products.
In the cases of meropenem, biapenem and ertapenem,
introduction of a 1â-methyl group to the carbapenem skeleton
enhances metabolic stability to renal dehydropeptidase-1
(DHP-1) and leads to high antibacterial potency.7 Doripenem
hydrate (S-4661, 1), which was discovered by Shionogi
Research Laboratories, Shionogi & Co., Ltd., Osaka, Japan,
* Corresponding author. E-mail: yoshiyuki.masui@shionogi.co.jp.
† Current address: Clinical Trial Drugs Producing Unit, Manufacturing
Technology R&D Laboratories, Shionogi & Co., Ltd., Kuise Terajima 2-chome,
Amagasaki, Hyogo 660-0813, Japan.
‡ Current address: Kuise Plant, Manufacturing Division, Shionogi & Co.,
Ltd., Kuise Terajima 2-chome, Amagasaki, Hyogo 660-0813, Japan.
§ Current address: Corporate Quality Assurance Department, Shionogi & Co.,
Ltd., Kuise Terajima 2-chome, Amagasaki, Hyogo 660-0813, Japan.
(1) (a) For a brief history: Sunagawa, M.; Sasaki, A Heterocycles 2001, 54,
497-528. (b) Kawamoto, I. Drugs Future 1998, 23, 181-189. (c) Coulton,
S.; Hunt, E. In Progress in Medicinal Chemistry; Ellis, G. P., Luscombe,
D. K., Eds.; Elsevier Science: New York, 1996; Vol. 33, pp 99-145. (d)
Sader, H. S.; Gales, A. C. Drugs 2001, 61, 553-564.
(2) (a) Leanza, W. J.; Wildonger, K. J.; Miller, T. W.; Christensen, B. G. J.
Med. Chem. 1979, 22, 1435-1436. (b) Kropp, H.; Sundelof, J. G.; Kahan,
J. S.; Kahan, F. M.; Birnbaum, J. Antimicrob. Agents Chemother. 1980,
17, 993-1000. (c) Kahan, F. M.; Kropp, H.; Sundelof, J. G.; Birnbaum, J.
J. Antimicrob. Chemother. 1983, 12 (Suppl. D), 1-35.
(3) Miyadera, T.; Sugimura, Y.; Hashomoto, T.; Tanaka, T.; Iino, K.; Shibata,
T.; Sugawara, S. J. Antibiot. 1983, 36, 1034-1039.
(4) Sunagawa, I.; Matsumura, H.; Inoue, T.; Fukasawa, M.; Kato, M. J. Antibiot.
1990, 43, 519-532.
(5) Hiraishi, T.; Miyata, A.; Hara, T.; Araake, M.; Ogawa, H. Jpn. J. Antibiot.
2001, 54, 581-595.
(8) Iso, Y.; Irie, T.; Nishino, Y.; Motokawa, K.; Nishitani, Y. J. Antibiot. 1996,
49, 199-209.
(6) Fuchs, P. C.; Barry, A. L.; Brown, S. D. Antimicrob. Agents Chemother.
2001, 45, 1915-1918 and references therein.
(7) Shih, D. H.; Baker, F.; Cama, L.; Christensen, B. G. Heterocycles 1984,
21, 29-40.
(9) Iso, Y.; Irie, T.; Iwaki, T.; Kii, M.; Sendo, Y.; Motokawa, K.; Nishitani, Y.
J. Antibiot. 1996, 49, 478-484.
(10) Ohtani, M.; Watanabe, F.; Narisada, M. J. Org. Chem. 1984, 49, 5271-
5272.
846
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Vol. 7, No. 6, 2003 / Organic Process Research & Development
10.1021/op034088n CCC: $25.00 © 2003 American Chemical Society
Published on Web 09/24/2003

Scheme 1
In the catalytic hydrogenolysis process, we found an
extremely effective extraction process to remove p-toluidine
and most of the other organic impurities using a THF/water
system coupled with an inorganic salt to achieve a salting-
out effect. The number of phase cuts, % recovery, and purity
of compound 1 were examined by using a model system for
the extraction in the presence of various inorganic salts. The
aqueous layer was washed with THF (38 mL) until its
amount was less than 5.5 g. The results are summarized in
Table 1. The most important parameter is % purity. The
theoretical water content is 4.1 wt %. With MgCl2 and LiCl
(entries 1 and 2), the amount of the residual inorganic salt
was less than 0.1% because of their high solubility in aqueous
MeOH. However, with the other salts (entries 3-7), residual
salts were left in the product (8-30 wt %) because of their
poor solubility in aqueous MeOH. LiCl required more phase
cuts than MgCl2. Therefore, we chose MgCl2 as an additive.
After the hydrogenolysis, MgCl2 was added to the reaction
mixture. As expected, after extraction the aqueous layer
contained less than 0.1 wt % of p-toluidine. In addition,
interestingly, MgCl2 increased solubility of compound 1 in
the aqueous layer.14 Thus, MgCl2 was used also as an additive
to the biphasic reaction mixture to prevent precipitation
during the hydrogenolysis and extraction. In a pilot proce-
dure, the number of phase cuts was reduced by addition of
THF after hydrogenolysis to shorten operating times (see
Experimental Section).
an efficient and practical synthesis of compound 1 from
PNB-protected enolphophate 2b7,12 and N-(p-nitrobenzyl-
oxycarbonyl()PNZ))-protected aminomethylpyrrolidine 3c.11a,b
This process is amenable to large-scale production. Enol-
phosphate 2b is also used for the synthesis of ertapenem as
a starting material.13 We have already reported an efficient
and practical large-scale synthesis of aminomethylpyrrolidine
3c in our previous paper.11b Both the enolphophate 2b and
aminomethylpyrrolidine 3c are now commercially available.
Results and Discussion
Both deprotection processes, cleavage using Lewis acid
(AlCl3)-anisole and catalytic hydrogenolysis using Pd/C, to
give compound 1 required chromatographic purification on
Diaion HP-20 to remove impurities before this study. In the
original process (Scheme 2)8,9 and the first-generation process
(Scheme 3), an AlCl3-anisole system was used for the
deprotection. The reaction mixture contained aluminum ion
and numerous organic impurities (anisole, methoxybenzene
derivatives and unknown water-soluble organic compounds).
Anisole and methoxybenzene derivatives are easily removed
by extraction. However, aluminum ion and several unknown
organic impurities cannot be removed completely by extrac-
tion using acetylacetone. They were left in the API without
chromatographic purification. On the other hand, after
replacing the N-BOC or N-PMZ group with the N-PNZ
group, we tried deprotection by catalytic hydrogenolysis with
Pd/C. In this case, however, chromatographic purification
was still necessary because the reaction mixture contained
numerous kinds of impurities (p-toluidine and several
unknown water-soluble organic compounds) which could not
be removed completely by extraction because of their high
solubility in water.
To increase the yield and to avoid the chromatographic
purification, we then developed an improved process for the
synthesis of compound 1 which is shown in Scheme 4.
Compound 5c was synthesized by the coupling reaction
between PNB-protected enolphosphate 2b and in situ in-
termediate mercaptopyrrolidine 4c, which was prepared
from N-PNZ-protected aminomethylpyrrolidine 3c, in 88%
yield. Catalytic hydrogenolysis of compound 5c with Pd/C
in the presence of MgCl2 in aqueous THF followed by an
improved workup (removal of Pd/C by filtration, extrac-
tion, crystallization) afforded compound 1 as a nonsterile
crystalline powder in 73% yield. The nonsterile crystal was
sterilized and recrystallized to give compound 1 as a
sterile API in 88% yield. The overall yield of compound 1
from compound 5c was 64%, 15% higher than that by the
first-generation process. The amounts of residual Pd and
Mg in the API were lower than 20 ppm and 0.1%, re-
spectively. The quality of API which was afforded by the
improved procedure without chromatographic purification
was satisfactory. This new process is more practical and
effective than the previous process because it requires no
chromatographic purification and affords the target com-
(11) (a) A portion of this study was patented. Nishino, Y.; Yuasa, T.; Komurasaki,
T.; Kakinuma, M.; Masui, T.; Kobayashi, M. Patent Application No. JP
2001-140782. (b) Nishino, Y.; Komurasaki, T.; Yuasa, T.; Kakinuma, M.;
Izumi, K.; Kobayashi, M.; Fujiie, S.; Gotoh, T.; Masui, Y.; Hajima, M.;
Takahira, M.; Okuyama, A.; Kataoka, T. Org. Process Res. DeV. 2003, 7,
649-654.
(12) (a) There are many efficient approaches to compound 2b: Berks, A. H.
Tetrahedron 1996, 52, 331-375. (b) This is commercially available from
Takasago, Kaneka, and Nisso companies.
(13) Brands, K. M. J.; Jobson, R. B.; Conrad, K. M.; Williams, J. M.; Pipik, B.;
Cameron, M.; Davies, A. J.; Houghton, P. G.; Ashwood, M. S.; Cottrell, I.
F.; Reamer, R. A.; Kennedy, D. J.; Dolling, U.-H.; Reider, P. J. J. Org.
Chem. 2002, 67, 4771-4776.
(14) MgCl2‚6H2O was dissolved in a solution of compound 1 (0.1 g) in water
(2 mL) at room temperature. Then THF (3 mL) was added to the solution
at room temperature with stirring: (entry no., the amount of MgCl2‚6H2O,
layer, result), (entry 1, 0 g, homogeneous, crystallized after 2 h), (entry 2,
0.06 g, homogeneous, immediately crystallized), (entry 3, 0.11 g, biphasic,
slowly crystallized from aqueous layer after 0.5 h), (entry 4, 0.23 g, biphasic,
no crystallization). MgCl2 decreased solubility of compound 1 in homoge-
neous aqueous THF solution (entries 1 and 2). After appearance of aqueous
and organic layers by salting-out effect (entries 3 and 4), compound 1 existed
in the aqueous layer. The solubility of compound 1 with 0.23 g of MgCl2
in the aqueous layer was larger than that with 0.11 g of MgCl2. Thus, MgCl2
increased solubility of compound 1 in the aqueous layer.
Vol. 7, No. 6, 2003 / Organic Process Research & Development
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847

Scheme 2. Original process for medicinal chemistry (bench scale)
Scheme 3. First-generation process (pilot scale)
Experimental Section
Materials and Instrumentations. Diphenylmethyl
(4R,5S,6S)-6-[(1R)-1-hydroxyethyl]-4-methyl-3-[[(3S,5S)-1-
(tert-butoxycarbonyl)-5-[N-sulfamoyl-N-(tert-butoxycarbo-
nyl)aminomethyl]pyrrolidin-3-yl]thio]-7-oxo-1-azabicyclo-
[3.2.0]hept-2-ene-2-carboxylate (5b) was prepared according
to the literature method.9 4-Nitrobenzyl (4R,5S,6S)-3-[(di-
phenylphosphono)oxy]-6-[(1R)-1-hydroxyethyl]-4-methyl-7-
oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate (2b) and
(2S,4S)-4-acetylthio-2-(N-sulfamoyl-tert-butoxycarbonylami-
nomethyl)-1-(4-nitrobenzyloxycarbonyl)pyrrolidine (3c) are
commercially available. All commercially available materials
and solvents were used as received. NMR experiments were
conducted by using a MERCURY 300 and a INOVA 500
NMR spectrometer (Varian). IR spectra were obtained on a
MAGNA 560 FT-IR spectrophotometer (Nicolet).
Preparation of (4R,5S,6S)-6-[(1R)-1-Hydrozyethyl]-4-
methyl-3-[[(3S,5S)-5-(sulfamoylaminomethyl)pyrrolidin-
3-yl]thio]-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carbox-
ylic Acid Hydrate (Doripenem Hydrate: 1) as a Sterile
Active Pharmaceutical Ingredient (API) by Deprotection
of Compound 5b Followed by Purification, Sterilization,
and Crystallization. A mixture of compound 5b (11.0 kg,
14.0 mol) in CH2Cl2 (160 L) was added dropwise to a
solution of AlCl3 (11.2 kg) in anisole (110 L) at 2 °C. After
the addition, the reaction mixture was cooled to -10 °C and
then was added dropwise to a solution of NaHCO3 (4.4 kg)
in water (154 L) at 2 °C. After the aqueous layer was
separated, acetylacetone (33.6 kg) was added. Aqueous 15%
Na2CO3 (ca. 100 kg) was added dropwise to the aqueous
extract at 3 °C to adjust the pH to 5.0. After stirring at 3 °C
for 30 min, the mixture was washed with CH2Cl2 (122 L).
After addition of acetylacetone (27.5 kg), the mixture was
washed with CH2Cl2 (61 L × 2). Aqueous 15% Na2CO3 was
added dropwise to the aqueous extract at 3 °C to adjust the
pH to 5.5. After degassing in vacuo at 5 °C for 50 min, the
solution (ca. 300 kg) was chromatographed on a Diaion
HP-20 column. Eluent (ca. 1400 kg) of 7% EtOH was
collected and concentrated by filtration through a RO mem-
brane to give the filtrate (190 kg). The filtrate was concen-
trated to 50 kg and was decolorized with activated carbon
(0.18 kg). The filtrate was filtered through an ultrafiltration
Table 1. Screening of inorganic salts as additives in model
system for extraction after deprotection of compound 5ca
number of
wt of
phase cuts, aq layer, % recovery
% purityc
of 1
entry salt
times
g
of 1
1
2
3
MgCl2
LiCl
NaBr
4
6
4
3
5
4
3
5
3.5
5.4
3.3
3.1
3.9
3.0
4.0
4.2
82
84
84
38
90
83
86
97
96
88
88
83
77
66
4b BaCl2
5b NaCl
6b KCl
7
8
KBr
CaCl2
no crystallization occurred
a Extraction conditions: 1 (1.0 g) in THF (15.6 mL)-water (10.4 mL); after
addition of a salt (1.2 g), the aqueous layer was separated. Crystallization was
carried out as described in the Experimental Section. b Before crystallization,
inorganic salt which was precipitated from the aqueous layer was removed by
filtration. c wt % measured on HPLC analysis.
pound 1 as a sterile API in higher yield. This process is
amenable to large-scale production. In fact, several kilograms
of compound 1 for clinical trials were successfully prepared
by this process.
Conclusions
We developed and described a practical multikilogram-
scale synthesis of doripenem hydrate (1) by deprotection of
compound 5c which was prepared from enolphosphate 2b
and N-PNZ-protected aminomethylpyrrolidine 3c. We found
effective extraction conditions to remove p-toluidine and
most other organic impurities using THF/water and MgCl2.
The reported process requires no chromatographic purifica-
tion and affords compound 1 as a sterile crystalline mono-
hydrate in an efficient yield. This process is practical and
efficient. In fact, this process has been scaled up in a pilot
plant to make compound 1 for clinical studies in >10-kg
scale.
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Vol. 7, No. 6, 2003 / Organic Process Research & Development

Scheme 4. Improved process (pilot scale)
membrane to remove endotoxin. MeOH (25 L) and seed
crystal (16 g) were added to the filtrate (50 kg) at 7 °C.
After the mixture was stirred at 15 °C for 20 min, MeOH
(125 L) was added dropwise at 10 °C over 1 h. The precipi-
tate was collected by filtration, washed with 95% MeOH
kg) in MeOH (140 kg) was stirred at 65 °C for 2.5 h. After
cooling the reaction mixture below 25 °C, the mixture was
concentrated to 110 L under reduced pressure. The resultant
concentrate was poured into a mixture of EtOAc (225 kg)
and water (250 kg). The organic layer was separated and
was washed with an aqueous 5% NaCl (175 kg × 3). Each
aqueous layer was back-extracted with EtOAc (90 kg). The
combined extracts were concentrated to ca. 70 kg, then
EtOAc (180 kg) was added to the residue. The mixture was
concentrated again to give the concentrate (ca. 70 kg)
containing 4c. Enolphosphate 2b (30.0 kg, 50.5 mol) and
DMF (143 kg) were added to the concentrate. After cooling
the mixture to 0 °C, diisopropylethylamine (iPr2NEt, 9.1 kg)
was added. The reaction mixture was stirred at 5 °C for 18
h and then was poured into a mixture of EtOAc (200 kg)
and water (225 L). The organic layer was separated and
washed with aqueous 0.7% HCl (153 kg), 5% NaHCO3 (63
kg), and 5% NaCl (90 kg × 2). Each aqueous layer was
back-extracted with EtOAc (90 kg). The combined extracts
were concentrated to ca. 104 L, and then EtOAc (180 kg ×
2) was added to the residue. The mixture was concentrated
again under reduced pressure to remove water. Toluene (365
kg) was added dropwise to the residue (155 L) over 0.5 h.
The precipitate was collected by filtration and dried to give
1
and dried to give 18,9 (2.98 kg, 49%) as a sterile API. H
NMR (500 MHz, D2O) δ 1.23 (d, 3H, J ) 7.2 Hz, CH3-
on 4-position), 1.30 (d, 3H, J ) 6.4 Hz, CH3CHOH-), 1.77
(ddd, 1H, J ) 6.6, 9.2, and 14.9 Hz, H-4â of pyrrolidinyl),
2.75 (dt, 1H, J ) 14.3 and 8.0 Hz, H-4R of pyrrolidinyl),
3.38 (dq, 1H, J ) 7.2 and 9.3 Hz, H-4R), 3.44 (dd, 1H, J )
4.2 and 12.4 Hz, H-2R of pyrrolidinyl), 3.44 (dd, 1H, J )
8.3 and 15.0 Hz, one of -CH2-NHSO2NH2), 3.48 (dd, 1H,
J ) 2.5 and 6.1 Hz, H-6), 3.55 (dd, 1H, J ) 4.8 and 15.0
Hz, one of -CH2-NHSO2NH2), 3.72 (dd, 1H, J ) 7.0 and
12.4 Hz, H-2â of pyrrolidinyl), 3.95 (qd, 1H, J ) 4.8 and
8.5 Hz, H-5R of pyrrolidinyl), 4.06 (qd, 1H, J ) 7.4 and
4.2 Hz, H-3R of pyrrolidinyl), 4.24 (dd, 1H, J ) 2.5 and
9.3 Hz, H-5), 4.26 (m, 1H, -CH(OH)CH3).
Screening of Inorganic Salts as Additives in Model
System for Extraction after Deprotection of Compound
5c. An inorganic salt (1.2 g) was dissolved in a solution of
compound 1 (1.0 g) in THF (15.6 mL)-water (10.4 mL).
The aqueous layer was separated and washed with THF (38
mL) until its weight was less than 5.5 g because a smaller
amount of the aqueous extract gives smaller crystallizing
volume and leads to higher throughput. If inorganic salt pre-
cipitated from the solution, it was removed by filtration.
MeOH (20 mL) was added to the obtained aqueous extract.
The precipitate was collected by filtration, and dried to re-
cover compound 1. The results are summarized in Table 1.
Preparation of 4-Nitrobenzyl (4R,5S,6S)-6-[(1R)-1-
Hydroxyethyl]-4-methyl-3-[[(3S,5S)-1-(4-nitrobenzyloxy-
carbonyl)-5-(sulfamoylaminomethyl)pyrrolidin-3-yl]thio]-
7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate (5c). A
mixture of 3c11b (33.6 kg, 63.1 mol) and 98% H2SO4 (15.8
5c (32.5 kg, 88%): mp 160-180 °C dec. In the 1H and 13
C
NMR spectra, a 3:2 mixture of cis and trans C-N rotamers
was observed. 1H NMR (500 MHz, CD3CN) δ 1.21 (d, 3H,
J ) 6.3 Hz, CH3CHOH-), 1.22 (d, 3H, J ) 7.5 Hz, CH3-
on 4-position), 1.81 (m, 1H, one of H-4 of pyrrolidinyl, major
isomer), 1.91 (m, 1H, one of H-4 of pyrrolidinyl, minor
isomer), 2.54 (m, 1H, one of H-4 of pyrrolidinyl), 3.17 (m,
1H, one of H-2 of pyrrolidinyl, minor isomer), 3.26 (m, 1H,
H-5 of pyrrolidinyl, minor isomer), 3.26 (m, 1H, one of
H-2 of pyrrolidinyl, major isomer), 3.30 (m, 1H, H-6), 3.31
(m, 1H, H-5 of pyrrolidinyl, major isomer), 3.49 (m, 1H,
H-4R), 3.76 (m, 1H, H-3 of pyrrolidinyl, minor isomer), 3.80
Vol. 7, No. 6, 2003 / Organic Process Research & Development
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849

(m, 1H, H-3 of pyrrolidinyl, major isomer), 4.05 (m, 2H,
-CH2-NHSO2NH2), 4.11 (m, 1H, -CH(OH)CH3), 4.11 (m,
1H, one of H-2 of pyrrolidinyl), 4.25 (m, 1H, H-5), 5.22 (s,
2H, -CH2- of of PNZ-N<), 5.26 (d, 1H, J ) 14.3 Hz, one
of -CH2- of PNB ester), 5.43 (t, 1H, J ) 6.5 Hz,
-SO2NHCH2- of minor isomer), 5.45 (d, 1H, J ) 14.3 Hz,
one of -CH2- of PNB ester), 5.65 (t, 1H, J ) 6.5 Hz,
-SO2NHCH2- of major isomer), 7.61 (d, 2H, J ) 8.5 Hz,
meta-H of nitrophenyl of PNZ-N-), 7.69 (d, 2H, J )
8.5 Hz, meta-H of nitrophenyl of PNB ester), 8.22 (d, 4H, J
) 8.5 Hz, ortho-H of nitrophenyl). 13C NMR (125 MHz,
CD3CN) δ 17.7, 21.9 (minor), 22.0 (major), 35.1 (major),
35.5 (minor), 40.4 (minor), 40.9 (major), 44.4, 46.7 (minor),
46.9 (major), 55.9 (major), 56.3 (minor), 56.5, 57.5 (minor),
58.3 (major), 60.7, 65.7, 66.1, 66.4 (major), 66.5 (minor),
124.6, 124.7, 125.1 (minor), 128.9 (major), 129.1 (minor),
129.2, 129.3 (minor), 144.7, 145.6, 148.5, 148.6, 151.9
(major), 152.1 (minor), 155.0, 155.8, 161.5, 175.1. IR (KBr)
1769, 1698, 1521, 1345 cm-1. MS (Ion Mode: FAB+) m/z
735 [M + H]+. Anal. Calcd for C30H34N6O12S2: C, 49.04;
H, 4.66; N, 11.44; S, 8.73. Found: C, 48.77; H, 4.79; N,
11.19; S, 8.63.
previous aqueous suspension of 1. MeOH (75 L) was added
dropwise to the suspension. The mixture was stirred at -10
°C for 1 h. The precipitate was collected by filtration, washed
with MeOH, and dried to give 18,9 (3.84 kg, 73%) as a crude
nonsterile crystal.
Purification, Sterilization, and Crystallization to Give
1 as a Sterile API. Crude 1 (3.30 kg, 7.53 mol) was
dissolved in water (66 L) at 55 °C. The solution was filtered
through a funnel precoated with activated carbon (0.10 kg),
a membrane filter (0.2 µm), a membrane for the ultrafiltra-
tion, and a filter for the sterilization. Then the filtrate was
cooled to room temperature. After stirring at room temper-
ature for 0.5 h, the mixture was stirred at 2 °C for 2 h.
2-Propanol (26.1 kg), sterilized with filtration prior to use,
was added dropwise over 80 min. After stirring at -5 °C
for 4 h, the mixture was stirred at -10 °C overnight. The
precipitate was collected by filtration, washed with sterilized
aqueous 80% 2-propanol, and dried to give 18,9 (2.89 kg,
88%) as a sterile API. p-Toluidine and the other organic
impurities were determined by HPLC: Each was less than
0.1% by area. Residual Pd: less than 20 ppm. Residual Mg:
less than 0.1%.
Deprotection of Compound 5c. Deionized water (40 L),
10 wt % Pd/C (5.0 kg), and MgCl2‚6H2O (1.4 kg) were added
to a solution of compound 5c (8.8 kg, 12.0 mol) in THF (60
L). The suspension was stirred from 26 to 38 °C for 2 h
under a H2 atmosphere (0.5 MPa). The used Pd/C was
removed by filtration and washed with a mixture of THF
(18 L) and deionized water (12 L). MgCl2‚6H2O (0.7 kg)
was dissolved in the combined filtrates. After addition of
THF (300 L) to the mixture, the aqueous layer was separated
at 26 °C. After cooling the extract to 0 °C, MeOH (40 L)
and seed crystals (10 g) were added to the extract. After
MgCl2‚6H2O (0.7 kg × 2) was added to the organic layer,
the resulting aqueous layer was separated and added to the
Acknowledgment
We are grateful to Dr. K. Yoshikawa, Ms. S. Sekimoto,
Mr. T. Toya, Mr. K. Hamada, Ms. M. Hiura, Dr. J. Kikuchi,
and their co-workers for analytical data, to Mr. K. Kishimoto,
Mr. Y. Okumura, Mr. M. Toyoda, Mr. I. Nanjo, and their
co-workers for scale-up operations, and to Mr. H. Nakanishi
and co-workers for process engineering data. We also thank
Dr. Y. Nishitani, Dr. M. Kume, Dr. T. Irie, Mr. M. Hajima,
Mr. M. Uenaka, and Mr. A. Okuyama for helpful discussion.
Received for review June 29, 2003.
OP034088N
850
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Vol. 7, No. 6, 2003 / Organic Process Research & Development