Practical synthetic method of (2Z,3E)-1,4-Diphenylbutadiene T-2639, an inhibitor of plasminogen activator inhibitor-1 (PAI-1) production

Article abstract of DOI:10.1021/op9000719

A practical synthetic method of (2Z,3E)-1,4-diphenylbutadiene derivative T-2369 (1), a potent inhibitor of plasminogen activator inhibitor-1 (PAI-1) production, is described. Conditions of Stobbe condensation in the conventional synthesis of T-2369 were e

Full text of DOI:10.1021/op9000719

Organic Process Research & Development 2009, 13, 760–763
Practical Synthetic Method of (2Z,3E)-1,4-Diphenylbutadiene T-2639, an Inhibitor of
Plasminogen Activator Inhibitor-1 (PAI-1) Production
Hiroshi Miyazaki, Hiroshi Ohmizu, and Tsuyoshi Ogiku*
Medicinal Chemistry Laboratory, Mitsubishi Tanabe Pharma Co., Ltd., 3-16-89, Kashima, Yodogawa, Osaka 532-8505, Japan
Abstract:
A practical synthetic method of (2Z,3E)-1,4-diphenylbutadiene
derivative T-2369 (1), a potent inhibitor of plasminogen activator
inhibitor-1 (PAI-1) production, is described. Conditions of Stobbe
condensation in the conventional synthesis of T-2369 were exam-
ined, and a new method to efficiently synthesize the key intermedi-
ate, (2Z,3E)-2,was derived. (2Z,3E)-2 was selectively obtained in
82% (with 91:9 selectivity) by predominant precipitation of
Figure 1. Structures of T-2639 (1) and the key intermediate
(2Z,3E)-2.
(2Z,3E)-2 Na salt and in situ isomerization of (2E,3E)-2 to
(2Z,3E)-2.
(Scheme 1), has some drawbacks. Notably, the second Stobbe
condensation of succinate 45 with 3′,5′-dimethoxyacetophenone
Introduction
5 is unselective, leading to a mixture of two isomers (2Z,3E)-
It is well-known that plasminogen activator inhibitor-1 (PAI-
1), a specific inhibitor of both tissue-type plasminogen activator
and (2E,3E)-2. Moreover, due to the difficult separation of the
two isomers as carboxylic acids, the mixture of isomers has to
and urokinase-type plasminogen activator, plays an important
be converted into the corresponding methoxymethyl (MOM)
esters. After separation by silica gel column chromatography,
(2Z,3E)-6 is deprotected to (2Z,3E)-2. For scale-up synthesis
of T-2639, it is necessary to overcome these drawbacks. In this
paper, we report a practical synthetic method of T-2639.
role in regulation of the fibrinolytic system.1 As inhibition of
PAI-1 activity or reduction of its production is believed to result
in antithrombotic effect, a number of small molecules with the
potential to inhibit PAI-1 or suppress PAI-1 production have
recently been studied.2,3
We have previously reported T-2639 (1, Figure 1)4 as a
potent orally active inhibitor of PAI-1 with good DMPK and
strong antithrombotic activity. However, the synthetic route of
T-2639, which mainly consists of two Stobbe condensations
Results and Discussion
In order to improve selectivity in the second Stobbe
condensation, we first examined the reaction conditions. The
results are shown in Table 1. Stobbe condensation proceeded
according to the amount of t-BuOK used, but the ratio of
(2Z,3E) to (2E,3E) was less than 2 to 1 (entries 1-4).6 Heating
in t-BuOH at 60 °C did not improve the selectivity (entry 5).
Next, the effect of the solvent on selectivity was examined using
24% w/w NaOMe solution in MeOH as a base. In the case of
t-BuOH as a solvent, the selectivity was slightly improved (entry
6). However, in the case of other solvents including MeOH,
THF, or toluene, no beneficial effect was observed (entries
7-9). Although we could not find ideal conditions to improve
selectivity for (2Z,3E)-2, the use of toluene as a solvent allowed
a small amount of (2Z,3E)-2 Na salt to precipitate as crystals
in the reaction vessel after cooling, indicating that crystallinity
of (2Z,3E)-2 Na salt in toluene is higher than that of (2E,3E)-2
Na salt. Thus, we anticipated that (2Z,3E)-2 Na salt could
predominantly be obtained if isomerization of (2E,3E)-2 to
(2Z,3E)-2 takes place and the generated (2Z,3E)-2 is separated
* Author to whom correspondence may be sent. Fax +81-6-6300-2564.
E-mail: ogiku.tsuyoshi@me.mt-pharma.co.jp.
(1) Schneiderman, J.; Loskutoff, D. J. Trends CardioVasc. Med. 1991, 1,
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(2) (a) Folkes, A.; Roe, M. B.; Sohal, S.; Golec, J.; Faint, R.; Brooks, T.;
Charlton, P. Bioorg. Med. Chem. Lett. 2001, 11, 2589. (b) Folkes, A.;
Brown, S. D.; Canne, L. E.; Chan, J.; Engelhardt, E.; Epshteyn, S.;
Faint, R.; Golec, J.; Hanel, A.; Kearney, E.; Leahy, J. W.; Mac, M.;
Matthews, D.; Prisbylla, M. P.; Sanderson, J.; Simon, R. J.; Tesfai,
Z.; Vicker, N.; Wang, S.; Webb, R. R.; Charlton, P. Bioorg. Med.
Chem. Lett. 2002, 12, 1063. (c) Wang, S.; Golec, J.; Miller, W.;
Milutinovic, S.; Folkes, A.; Williams, S.; Brooks, T.; Hardman, K.;
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12, 2367. (d) De Nanteuil, G.; Lila-Ambroise, C.; Rupin, A.; Vallez,
M. O.; Verbeuren, T. J. Bioorg. Med. Chem. Lett. 2003, 13, 1705. (e)
Ye, B.; Bauer, S.; Buckman, B. O.; Ghannam, A.; Griedel, B. D.;
Khim, S. K.; Lee, W.; Sacchi, K. L.; Shaw, K. J.; Liang, A.; Wu, Q.;
Zhao, Z. Bioorg. Med. Chem. Lett. 2003, 13, 3361. (f) Ye, B.; Chou,
Y. L.; Karanjawala, R.; Lee, W.; Lu, S. F.; Shaw, K. J.; Jones, S.;
Lentz, D.; Liang, A.; Tseng, J. L.; Wu, Q.; Zhao, Z. Bioorg. Med.
Chem. Lett. 2004, 14, 761. (g) Gopalsamy, A.; Kincaid, S. L.;
Ellingboe, J. W.; Groeling, T. M.; Antrilli, T. M.; Krishnamurthy,
G.; Aulabaugh, A.; Friedrichs, G. S.; Crandall, D. L. Bioorg. Med.
Chem. Lett. 2004, 14, 3477. (h) Hu, B.; Jetter, J. W.; Wrobel, J. E.;
Antrilli, T. M.; Bauer, J. S.; Di, L.; Polakowski, S.; Jain, U.; Crandall,
D. L. Bioorg. Med. Chem. Lett. 2005, 15, 3514.
(3) Elokdah, H.; Abou-Gharbia, M.; Hennan, J. K.; McFarlane, G.;
Mugford, C. P.; Krishnamurthy, G.; Crandall, D. L. J. Med. Chem.
2004, 47, 3491.
(5) Sai, H.; Ogiku, T.; Ohmizu, H.; Ohtani, A. Chem. Pharm. Bull. 2006,
54, 1686.
(4) Miyazaki, H.; Ogiku, T.; Sai, H.; Ohmizu, H.; Murakami, J.; Ohtani,
A. Bioorg. Med. Chem. Lett. 2008, 18, 6419.
(6) Even if the reaction time was extended to more than 5 h, further Stobbe
condensation in t-BuOH didn’t proceed.
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10.1021/op9000719 CCC: $40.75  2009 American Chemical Society
Published on Web 05/28/2009

Scheme 1. Conventional synthesis of T-2639 (1)
Table 1. Stobbe condensation of succinate 4 and
3′,5′-dimethoxyacetophenone 5 with various bases and
solventsa
Scheme 2. Selective preparation of (2Z,3E)-2 by
predominant precipitation of (2Z,3E)-2 Na salt and in situ
isomerization of (2E,3E)-2 to (2Z,3E)-2
ratiob
yield (%)
solvent
(2Z,3E)-2: (2Z,3E)-2 +
entry base (equiv) (3 v/w) temp. (2E,3E)-2 (2E,3E)-2
1
2
3
4
5
6
7
8
9
t-BuOK (1.0) t-BuOH rt
t-BuOK (1.2) t-BuOH rt
t-BuOK (1.5) t-BuOH rt
t-BuOK (2.0) t-BuOH rt
t-BuOK (1.5) t-BuOH 60 °C
NaOMec (1.5) t-BuOH reflux
NaOMec (1.5) MeOH reflux
0.8:1
1.3:1
1.9:1
2.0:1
1.9:1
2.9:1
1.3:1
1.5:1
1.8:1
1.8:1
3.4:1
11.5:1
45b
55b
70b
75b
79b
65d
67d
59d
57d
65d
78d
82d
NaOMec (1.5) THF
reflux
NaOMec (1.5) toluene reflux
10e NaOMec (1.5) toluene reflux
11f NaOMec (1.5) toluene reflux
12e,f NaOMec (1.5) toluene reflux
a 3′,5′-Dimethoxyacetophenone 5 was reacted with succinate 4 (1.2 equiv) for
5 h. b Ratio and yield were determined by 1H NMR of the reaction mixture after
acid quenching [relative integration ratio between
5 (δ ) 2.58 ppm, 3H),
(2Z,3E)-2 (δ ) 1.78 ppm, 3H) and (2E,3E)-2 (δ ) 2.44 ppm, 3H)]. c 24% w/w
NaOMe solution in MeOH was used. d Isolated yield (%). The ratio of
(2Z,3E)-2:(2E,3E)-2 was almost the same as that of the reaction mixture. e MeOH
originating from NaOMe solution was removed. f Powder of (2Z,3E)-2 Na salt
(0.01 equiv) was added to the reaction mixture, and the new mixture was heated
under refluxing for 2 h.
as a solid from the reaction mixture under the reaction conditions
(Scheme 2).7,8
observed, and the selectivity of the product was improved
((2Z,3E)-2:(2E,3E)-2 ) 3.4:1), indicating that predominant
precipitation of (2Z,3E)-2 Na salt and in situ isomerization
of (2E,3E)-2 to (2Z,3E)-2 occurred. The best result was
obtained by a combination of seeding and removal of
MeOH from the reaction system (entry 12).9,10 In this case,
selectivity was greatly improved by up to 11.5:1.
As described above, we could selectively prepare
(2Z,3E)-2.11 Actually, a scale-up synthesis of T-2639 using
this optimized method, in which the undesired isomer was
In order to accelerate isomerization of (2E,3E)-2 to
(2Z,3E)-2 and precipitation of (2Z,3E)-2 Na salt, MeOH
originating from NaOMe solution was removed during the
reaction (entry 10). However, the expected precipitation
of the salt was not observed, and the yield and selectivity
for (2Z,3E)-2 were not improved. Next, to precipitate the
desired salt, powder of (2Z,3E)-2 Na salt (0.01 equiv) was
added as seeds to the reaction mixture (entry 11). In this
case, generation of a substantial amount of the salt was
(9) See Experimental Section.
(7) In fact, the isomerization from (2E,3E)-2 to (2Z,3E)-2 had been
observed under the basic conditions. When (2E,3E)-2 had been treated
with t-BuOK (1.1-1.2 equiv) in t-BuOH at 50-60 °C for 10 min,
1:1 mixture of (2E,3E)-2 and (2Z,3E)-2 had been obtained, which had
been monitored by TLC.
(8) Because such salt precipitation was not observed with t-BuOK, the
effect of Na may be related to precipitation.
(10) NaOMe solution was used instead of powder NaOMe because it was
easy to handle in consideration of application to process chemistry.
The reaction will take place similarly even if powder NaOMe is used.
(11) It was possible to further enrich the isomeric purity of (2Z,3E)-2 via
further recrystallization from AcOEt, but in case the ratio of (2Z,3E)-
2:(2E,3E)-2 was 85:15 or more, (2E,3E)-2 didn’t influence the purity
of 1 (T-2639).
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Scheme 3. Scale-up synthesis of T-2639
aqueous NaHCO3 solution (100 mL). AcOEt (250 mL)
was added to the previous aqueous layer, and the mixture
was acidified with concd HCl below 15 °C (pH 2). The
organic and aqueous layers were separated, and the organic
layer was washed with 10% brine (100 mL) and saturated
brine (100 mL) and dried over MgSO4. After activated
charcoal (2 g, nacalai tesque, code: 079-09) was added to
the solution, the suspension was filtered, and the filtrate
was concentrated in Vacuo. The residue was diluted with
i-Pr2O and filtered to give 2 (19.1 g, 82%, (2Z,3E)-2:
(2E,3E)-2 ) 91:9) as a solid.
HPLC retention time: 2.8 min (elution with 35:65
acetonitrile/20 mM phosphate buffer, pH 6.5), relative
retention time (RRT) to 1 (T-2639): 0.47; IR (Nujol) 2924,
2853, 1710, 1685, 1603, 1589, 1451, 1424, 1274, 1206
removed by recrystallization in the final step, provided
up to 420 g of pure T-2639 without chromatography
(Scheme 3).
cm-1 1H NMR (CDCl3, 400 MHz) δ 8.00 (s, 1H),
;
7.60-7.70 (m, 2H), 7.30-7.45 (m, 3H), 6.40 (t, J ) 2.3
Hz, 1H), 6.33 (d, J ) 2.3 Hz, 2H), 3.80 (s, 6H), 3.53 (s,
3H), 1.78 (s, 3H); 13C NMR (CDCl3, 100 MHz) δ 172.1,
167.6, 160.5, 150.2, 144.9, 144.6, 134.7, 130.0, 129.8,
128.7, 128.0, 124.8, 104.6, 99.4, 55.3, 51.9, 23.6; MS ESI
m/z: 381 ([M - H]-); HR-MS ESI Calcd for C22H23O6
([M + H]+): 383.1495. Found: 383.1485.
1-Methyl 2-[1-(3′,5′-Dimethoxyphenyl)-(E)-ethylidene]-3-
[1-phenyl-(E)-methylidene]-4-succinic Acid ((2E,3E)-2).
HPLC retention time: 2.6 min (elution with 35:65 acetonitrile/
20 mM phosphate buffer pH 6.5), relative retention time (RRT)
to 1 (T-2639): 0.43; IR (ATR) 2841, 2524, 1711, 1658, 1592,
1426, 1316, 1205, 1157 cm-1; 1H NMR (CDCl3, 400 MHz) δ
7.50 (s, 1H), 7.25-7.40 (m, 5H), 6.22 (t, J ) 2.3 Hz, 1H),
5.85 (d, J ) 2.3 Hz, 2H), 3.79 (s, 3H), 3.54 (s, 6H), 2.44 (s,
3H); 13C NMR (CDCl3, 100 MHz) δ 172.6, 167.5, 160.1, 154.7,
144.8, 143.4, 135.0, 129.9, 129.4, 129.2, 128.3, 124.0, 103.9,
100.4, 55.1, 52.0, 23.1; MS ESI m/z: 381 ([M - H]-); HR-
MS ESI Calcd for C22H23O6 ([M + H]+): 383.1495. Found:
383.1485.
Methyl (Z)-3-(3′,5′-Dimethoxyphenyl)-2-[(E)-1-(4-meth-
ylpiperazin-1-ylcarbamoyl)-2-phenylvinyl]-2-butenoate Hy-
drochloride (1, T-2369). Oxalyl chloride (194 g, 133.3 mL,
1.52 mol) was added dropwise over 20 min to (2Z,3E)-2
(487 g, 1.27 mol, containing <10% of (2E,3E)-2) solution
in CH2Cl2 (1 L) and DMF (1 L). The reaction mixture
was stirred for 2 h and then concentrated in Vacuo. After
the residue was dissolved in THF (4 L), a mixture of Et3N
(214 mL, 1.52 mol) and 1-amino-4-methylpiperazine (168
mL, 1.52 mol) was added dropwise to the mixture,
maintaining the temperature below 20 °C. After 2 h, the
reaction mixture was diluted with AcOEt (4 L) and washed
with water (3 L) twice and brine (2 L). The organic layer
was dried over MgSO4 and concentrated in Vacuo. The
resulting oil was diluted with CH2Cl2 (3 L), and i-Pr2O
(1 L) was added. The mixture was concentrated in Vacuo
until the volume was about 1.5 L. After the mixture was
stirred for 5 h at room temperature, the crystals were
collected by filtration and washed with i-Pr2O. The crystals
obtained were next dissolved in EtOH (4.9 L), and concd
HCl (86 mL) was added dropwise at room temperature.
The reaction mixture was left at room temperature for 1 h
Conclusions
In conclusion, we have succeeded in improving the synthesis
of T-2639 using predominant precipitation of (2Z,3E)-2 Na salt
and in situ isomerization of (2E,3E)-2 to (2Z,3E)-2.
Experimental Section
General. Melting points were measured using a Bu¨chi
535 capillary melting point apparatus and are uncorrected.
IR spectra were recorded on a Perkin-Elmer Spectrum One
FT-IR spectrometer or Perkin-Elmer PARAGON1000. 1H
NMR and 13C NMR spectra were recorded on a Bruker
AVANCE 400 spectrometer or Varian UNITY INOVA500
with Me4Si as an internal standard. Mass spectra data were
obtained on a ThermoFisher FINNIGAN LXQ or a Q-TOF
Ultima API mass spectrometer. Elemental analyses were
obtained on a Perkin-Elmer 2400 II (C, H, N) and Dionex
DX-320 (Cl).
HPLC was conducted using an L-column ODS (3 µm, 4.6
mm × 50 mm). The mobile phase consisted of acetonitrile and
20 mM phosphate buffer, pH 6.5. The analytes were eluted at
a flow rate of 1 mL/min with column temperature of 40 °C
and observed by UV absorption at 210 nm.
1-Methyl 2-[1-(3′,5′-Dimethoxyphenyl)-(Z)-ethylidene]-
3-[1-phenyl-(E)-methylidene]-4-succinic Acid ((2Z,3E)-2).
Twenty-four percent w/w NaOMe solution in MeOH (20.5
g, 91.5 mmol) was added to a solution of dimethyl (E)-
2-benzylidenesuccinate5 (4) (17.1 g, 73 mmol) in toluene
(50 mL), and the mixture was stirred at 30-40 °C for 30
min. After 3′,5′-dimethoxyacetophenone (5) (11.0 g, 61
mmol) was added to the reaction mixture at 30-40 °C,
powder of (2Z,3E)-2 Na salts (233 mg, 0.61 mmol) was
added as seeds to the reaction mixture, and the mixture
was stirred at reflux for 1 h. After the salts were
precipitated, the mixture was concentrated in Vacuo until
the volume was about 22 mL (2 v/w of 3′,5′-dimethoxy-
acetophenone (5)). The mixture was again stirred at reflux
for 1 h. Acetic acid (2.9 g, 49 mmol) was then added to
the mixture below 15 °C, and ice-water was poured into
the mixture.12 The organic and aqueous layers were
separated, and the organic layer was washed with 5%
(12) It was confirmed that isomerization between (2Z,3E)-2 and (2E,3E)-2
didn’t occur during aqueous workup.
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and cooled in a refrigerator (-25 °C) for 14 h. Crystals
were collected by filtration and washed with Et2O (1 L)
to provide 420 g of 1 (64%).
55.5, 53.3, 52.4, 51.3, 43.2, 22.2; MS APCI m/z: 480 ([M +
H]+). Anal, Calcd for C27H33N3O5 ·HCl: C 62.84; H 6.64; N
8.14; Cl 6.87. Found: C 62.61; H 6.71; N 8.09; Cl 6.79.
Mp ) 235-240 °C; HPLC area: 99.7%; HPLC retention
time: 6.0 min (elution with 35:65 acetonitrile/20 mM phosphate
buffer pH 6.5); IR (Nujol) 3196, 2924, 2854, 1698, 1662, 1595,
1464, 1262 cm-1; 1H NMR (DMSO-d6, 500 MHz) δ 10.11 (br,
1H), 9.48 (s, 1H), 7.54 (d, J ) 7.2 Hz, 2H), 7.30-7.50 (m,
4H), 6.43 (s, 1H), 6.29 (d, J ) 1.8 Hz, 2H), 3.73 (s, 6H), 3.37
(s, 3H), 3.00-3.50 (m, 8H), 2.79 (s, 3H), 1.65 (s, 3H); 13C
NMR (CDCl3, 100 MHz) δ 168.9, 164.9, 160.8, 149.0, 143.5,
140.9, 134.7, 129.7, 129.5, 128.6, 128.6, 125.1, 104.7, 99.9,
Supporting Information Available
NMR chart of (2Z,3E)-2, (2E,3E)-2, and T-2639 (1). This
material is available free of charge via the Internet at
http://pubs.acs.org.
Received for review March 26, 2009.
OP9000719
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