Practical synthesis of spermine, thermospermine and norspermine

Article abstract of DOI:10.1248/cpb.c16-00355

Polyamines, such as spermine (1), thermospermine (2) and norspermine (3), are widely distributed in nature, and have multiple biological activities. In addition, many of their conjugates have potential for pharmacological use. Here, we present a solid-phase synthesis using our nitrobenzenesulfonyl (Ns) strategy, which can provide 1, 2 and 3 on a gram scale. This approach should be suitable for facile construction of a diverse library of polyamines.

Full text of DOI:10.1248/cpb.c16-00355

Vol. 64, No. 9
Chem. Pharm. Bull. 64, 1403–1407 (2016)
1403
Note
Practical Synthesis of Spermine, Thermospermine and Norspermine
Yuka Kariya,a Yuta Asanuma,a Makoto Inai,a Tomohiro Asakawa,a Kyoko Ohashi-Ito,b
,a
Hiroo Fukuda,b Masahiro Egi,a and Toshiyuki Kan*
a School of Pharmaceutical Sciences, University of Shizuoka; 52–1 Yada, Suruga-ku, Shizuoka 422–8526, Japan: and
b Department of Biological Sciences, Graduate School of Science, The University of Tokyo; 7–3–1 Hongo, Bunkyo-ku,
Tokyo 113–0033, Japan.
Received April 25, 2016; accepted June 6, 2016
Polyamines, such as spermine (1), thermospermine (2) and norspermine (3), are widely distributed in
nature, and have multiple biological activities. In addition, many of their conjugates have potential for phar-
macological use. Here, we present a solid-phase synthesis using our nitrobenzenesulfonyl (Ns) strategy, which
can provide 1, 2 and 3 on a gram scale. This approach should be suitable for facile construction of a diverse
library of polyamines.
Key words secondary amine synthesis; nitrobenzenesulfonyl (Ns) strategy; thermospermine; solid-phase
synthesis
Polyamines, especially of the spermine family (such as 1, 2 with a tert-butoxycarbonyl (Boc) group and alcohol with a
and 3) are ubiquitous in microorganisms, plants, and animals, tert-butyldimethylsilyl (TBS) group afforded 6 and 8, respec-
and have multiple biological activities.1–4) They interact with tively. Upon treatment of 6 and 8 with Cs2CO3 in the presence
nucleic acids and modulate DNA synthesis and cell prolifera- of tetrabutylammonium iodide, the desired coupling reaction
tion.5–7) Due to their biological significance, practical and ver- proceeded smoothly to give 9. Selective deprotection of TBS
satile synthetic methods are needed, but the lability of these ether was carried out by treatment with 10-camphorsulfonic
compounds to oxidation, as well as their highly polar nature, acid (CSA) in methanol. Although Mitsunobu reaction of al-
makes handling difficult. We have shown that the nitroben- cohol 10 and Ns-amide proceeded smoothly, we converted 10
zenesulfonyl (Ns) moiety is available as both a protecting to iodide 11 in a two-step sequence for ease of purification.
and activating group of amino group for flexible and practical Furthermore, iodide 11 opens up the possibility of further
synthesis of these compounds.8,9) More recently, some of the alkylation with sulfonamides such as 8 and 12 to extend the
present authors reported that thermospermine (2) plays a key polyamine chain. In order to synthesize thermospermine (2),
role in regulation of cell division and differentiation in plant alkylation of sulfonamide 12 was conducted with iodide 11,
meristems.10) Inspired by this interesting biological activity, which was readily prepared from diaminopropane by using
we wished to synthesize thermospermine (2) and related com- our protocol.11–13) After removal of the Boc group of 13, pri-
pounds on a large scale for biological testing and mechanistic mary amine 14 was attached to our resin 15, which is readily
investigations. Here, we describe practical gram-scale synthe- obtained from Merrifield resin.14–16) The alkoxytrityl chloride
ses of 1, 2 and 3 by means of a solid-phase method employing resin 15 offers significant advantages in terms of high reactiv-
our Ns strategy (Fig. 1).
ity, because the reactive site is well separated from the bulky
As shown in Chart 1, thermospermine (2) was synthesized polystyrene backbone. After deprotection of the Ns group was
by orthogonal extension of bromide 4 and alcohol 7. After accomplished by treatment with 2-mercaptoethanol and 1,8-di-
conversion of 4 and 7 to Ns amide, protection of sulfonamide azabicyclo[5.4.0]undec-7-ene (DBU), the product was cleaved
from the resin under acidic conditions. Upon removal of the
solvent, 2 was obtained in high purity. All spectroscopic
data (1H- and 13C-NMR spectra and MS) of synthetic 2 were
identical with those reported in the literature.17) This synthetic
protocol was applicable on a gram scale and we were able to
synthesize 1g of 2 in a pure form without the need for HPLC
purification. Synthetic thermospermine (2) showed the expect-
ed activity for regulation of cell division and differentiation in
meristems.10)
Next, we turned our attention to the synthesis of spermine
1 and norspermine 3. Considering the symmetrical struc-
tures of 1 and 3, we expected that these polyamines could be
synthesized via a simultaneous two-dimensional extension
strategy, as illustrated in Chart 2. Although we have reported
the synthesis of several protected spermine derivatives in the
solution phase, as well as in the solid phase,14) the present
method should be more convenient. Upon treatment of 2.2eq
of sulfonamide 17 with dibromobutane 18a or dibromopro-
Fig. 1. Structures of Spermine (1), Thermospermine (2) and Nor-
spermine (3)
*To whom correspondence should be addressed. e-mail: kant@u-shizuoka-ken.ac.jp
© 2016 The Pharmaceutical Society of Japan

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Vol. 64, No. 9 (2016)
Reagents and conditions: (a) 5, Na2CO3, CH2Cl2/H2O, (b) Boc2O, Et3N, DMAP, CH2Cl2, (c) TBSCl, imidazole, DMF, (d) Cs2CO3, TBAI, MeCN, 60°C, (e) CSA, MeOH,
(f) MsCl, Et3N, CH2Cl2, (g) NaI, butanone, 60°C, (h) Cs2CO3, MeCN, 60°C, (i) SOCl2, MeOH, (j) 15, N,N-diisopropylethylamine, DMAP, DMF, (k) 2-mercaptoethanol,
DBU, DMF, (l) 3% TFA in CH2Cl2.
Chart 1. Synthesis of Thermospermine (2) via an Orthogonal Extension Strategy
Reagents and conditions: (a) Cs2CO3, TBAI, MeCN, 60°C, (b) SOCl2, MeOH, (c) 15, N,N-diisopropylethylamine, DMAP, DMF, (d) 2-mercaptoethanol, DBU, DMF, (e)
3% TFA in CH2Cl2.
Chart 2. Synthesis of Spermine (1) and Norspermine (3) via a Simultaneous Extension Strategy
pane 18b in the presence of Cs2CO3 and a catalytic amount of
n-tetrabutylammonium iodide, the desired double alkylation
Experimental
General
Comments Nuclear
magnetic
resonance
reaction proceeded readily to provide 19a and b, respectively. [1H-NMR (500MHz), 13C-NMR (125MHz)] spectra were de-
This one-step construction is superior to the stepwise-elonga- termined on JEOL ECA-500 instrument. Chemical shifts for
tion of protected spermine and norspermine from diaminopro- 1H-NMR were reported in parts per million downfields from
pane. After removal of the Boc group, attachment of 20a or tetramethylsilane (δ) as the internal standard and coupling
b to 15 was performed by treatment with a catalytic amount constants were in hertz (Hz). The following abbreviations are
of N,N-dimethyl-4-aminopyridine (DMAP) and diisopropyl- used for spin multiplicity: s=singlet, d=doublet, t=triplet,
ethylamine. Subsequently, similar treatment to that used for q=quartet, m=multiplet, br=broad. Chemical shifts for
the preparation of thermospermine (2) provided the natural 13C-NMR were reported in ppm relative to the centerline of
products 1 and 3.
a triplet at 77.0ppm for deuteriochloroform. High-resolution
In conclusion, we have developed a practical, large-scale (HR)-MS were obtained on a BRUKER DALTONICS mi-
synthesis of polyamines via efficient extension reaction on a crOTOF electrospray ionization (ESI). IR spectra were record-
solid support based on the Ns strategy. This method does not ed on a SHIMADZU IRPrestige-21. Analytical TLC was per-
require tedious purification of polyamines, which can easily formed on Merck precoated analytical plates, 0.25mm thick,
be prepared on a gram scale. The method should be applicable silica gel 60F254. Preparative TLC separations were made on
to various types of polyamines, including long-chain poly- 7×20cm plates prepared with a 0.25mm layer of Merck silica
amines (LCPAs). This application is currently being investi- gel 60F254. Compounds were eluted from the adsorbent with
gated in our laboratories, and the results will be reported in 10% MeOH in chloroform. Column chromatography separa-
due course.
tions were performed on KANTO CHEMICAL Silica Gel 60
(spherical) 40–50µm, Silica Gel 60 (spherical) 63–210µm or
Silica Gel 60N (spherical, neutral) 63–210µm. Reagents and

Vol. 64, No. 9 (2016)
Chem. Pharm. Bull.
1405
solvents were commercial grades and were used as supplied Cs2CO3 (49.5g, 152mmol) at 0°C under an argon atmosphere.
with the following exceptions. 1) Dichloromethane, tetra- The mixture was stirred at 60°C for 2h. Then the mixture
hydrofuran and toluene: dried over molecular sieves 4A. 2) was quenched with saturated aqueous NH4Cl solution and
MeOH and acetonitrile: dried over molecular sieves 3A. All extracted with EtOAc. The organic layer was washed with
reactions sensitive to oxygen and/or moisture were conducted brine, dried over anhydrous MgSO4, filtered, and concentrated
under an argon atmosphere.
under reduced pressure. The residue was purified by silica gel
Bromide 6 To a solution of 4 (10.0g, 45.7mmol) in column chromatography (n-hexane–EtOAc=1:2) to afford 9
CH2Cl2 (100mL) and water (100mL) were added Na2CO3 (29.6g, 82%) as a light yellow amorphous solid. FT-IR (film)
(9.68g, 91.4mmol) and NsCl (222g, 43.5mmol) at 0°C. The cm−1: 657, 777, 837, 851, 961, 984, 1103, 1123, 1142, 1175,
mixture was stirred at room temperature for 1h. Then the 1258, 1292, 1356, 1377, 1441, 1462, 1539, 1551, 1734, 2858,
mixture was quenched with 10% citric acid and extracted with 2885, 2932, 2995, 3100. 1H-NMR (CDCl3) δ: 0.01 (s, 6H),
CH2Cl2. The organic layer was washed with brine, dried over 1.33 (s, 9H), 0.85 (s, 9H), 1.76 (dt, J=5.7, 7.4Hz, 2H), 2.01
anhydrous Na2SO4, filtered, and concentrated under reduced (quint, J=7.4Hz, 2H), 3.38–3.46 (m, 4H), 3.60 (t, J=5.7Hz,
pressure. The crude material was used for the following reac- 2H), 3.72 (t, J=7.4Hz, 2H), 7.58–7.62 (m, 1H), 7.63–7.78 (m,
tion without further purification. To a solution of crude materi- 5H), 7.98–8.04 (m, 1H), 8.23 (d, J=7.4Hz, 1H). 13C-NMR
al in CH2Cl2 (300mL) were added Et3N (8.35mL, 65.3mmol), (CDCl3) δ: −5.4, 18.3, 25.9, 27.8, 31.4, 44.7, 45.0, 45.4, 60.3,
DMAP (532mg, 4.35mmol), and Boc2O (11.4g, 52.2mmol) 85.4, 124.2, 124.5, 130.9, 131.8, 131.9, 133.1, 133.6, 134.5,
at 0°C. The mixture was stirred at room temperature for 147.6, 148.0, 150.2. HR-MS (ESI-TOF) m/z: 739.2085 (Calcd
1h. Then the mixture was quenched with saturated aque- for C29H44N4O11S2SiNa+ [M+Na]+: 739.2109).
ous NH4Cl solution and extracted with CH2Cl2. The organic
Iodide 2-Mer 11 To a solution of 9 (5.18g, 7.01mmol) in
layer was washed with brine, dried over anhydrous MgSO4, MeOH (24.1mL) was added CSA (838mg, 3.61mmol) at 0°C
filtered, and concentrated under reduced pressure. The residue under an argon atmosphere. The reaction mixture was stirred
was crystallized from EtOAc and n-hexane to afford 6 (18.4g, at room temperature for 1h. Then the mixture was quenched
quant. for the 2 steps from 4) as a light yellow solid. FT-IR with Et3N, and concentrated under reduced pressure. The
(film) cm−1: 719, 743, 773, 853, 1123, 1150, 1175, 1256, 1288, residue was poured into saturated aqueous NH4Cl solution,
1
1339, 1366, 1541, 1724, 2980, 3102. H-NMR (CDCl3) δ: 1.38 and the aqueous layer was extracted thoroughly with CH2Cl2.
(s, 9H), 2.32 (dt, J=6.8, 7.1Hz, 2H), 3.46 (t, J=6.8Hz, 2H), The organic layer was dried over anhydrous MgSO4, filtered,
3.92 (t, J=7.1Hz, 2H), 7.71–7.79 (m, 3H), 8.28–8.34 (m, 1H) and concentrated under reduced pressure. To a solution of
13C-NMR (CDCl3) δ: 27.8, 28.2, 29.6, 33.1, 46.7, 85.4, 124.3, the crude of alcohol 10 in CH2Cl2 (24.5mL) were added
131.8, 133.2, 133.3, 134.3, 147.5, 150.2. HR-MS (ESI-TOF) m/z: Et3N (3.10mL, 22.1mmol) and MsCl (1.79mL, 22.1mmol) at
445.0057 (Calcd for C14H19BrN2O6SNa+ [M+Na]+: 445.0039).
0°C under an argon atmosphere. The reaction mixture was
Ns Amide 8 To a solution of 7 (1.00g, 13.3mmol) in stirred at room temperature for 10min. Then the mixture was
CH2Cl2 (26.5mL) and water (26.5mL) were added Na2CO3 quenched with saturated aqueous NH4Cl solution, and it was
(1.41g, 13.3mmol) and NsCl (2.79g, 12.6mmol) at 0°C. The extracted thoroughly with CH2Cl2. The organic layer was
mixture was stirred at room temperature for 3h. Then the dried over anhydrous MgSO4, filtered, and concentrated under
mixture was quenched with 10% citric acid and extracted with reduced pressure. The crude material of mesylate was used
CH2Cl2. The organic layer was washed with brine, dried over for the following reaction without further purification. To a
anhydrous Na2SO4, filtered, and concentrated under reduced solution of the crude of mesylate in 2-butanone (25.4mL) was
pressure. The crude material was used for the following reac- added NaI (3.42g, 22.8mmol) at 0°C under an argon atmo-
tion without further purification. To a solution of crude mate- sphere. The reaction mixture was stirred at 60°C for 1h. Then
rial in N,N-dimethylformamide (DMF) (1.26mL) were added the mixture was quenched with saturated aqueous Na2S2O3
imidazole (2.57g, 37.8mmol) and TBSCl (2.85g, 18.9mmol) solution, and it was extracted thoroughly with CH2Cl2. The
at 0°C under an argon atmosphere. The mixture was stirred organic layer was washed with brine, dried over anhydrous
at room temperature for 3h. Then the mixture was quenched MgSO4, filtered, and concentrated under reduced pressure.
with saturated aqueous NH4Cl solution and extracted with The residue was purified by silica gel column chromatogra-
EtOAc. The organic layer was washed with brine, dried over phy (n-hexane–EtOAc=1:1) to afford 11 (4.02g, 78% for the
anhydrous MgSO4, filtered, and concentrated under reduced 3 steps from 9) as a light yellow solid. FT-IR (film) cm−1:
pressure. The residue was purified by silica gel column chro- 842, 852, 974, 1103, 1123, 1157, 1260, 1292, 1356, 1369, 1438,
1
matography (n-hexane–EtOAc=4:1) to afford 8 (4.68g, 96% 1543, 1734, 2937, 2980, 3099. H-NMR (CDCl3) δ: 1.37 (s,
for the 2 steps from 7) as a yellow oil. FT-IR (film) cm−1: 780, 9H), 2.02 (quint, J=7.4Hz, 2H), 2.13 (dt, J=7.4, 6.8Hz, 2H),
837, 854, 1094, 1169, 1345, 1360, 1420, 1536, 1560, 2858, 2929, 3.17 (t, J=6.8Hz, 2H), 3.39–3.47 (m, 4H), 3.73 (t, J=7.4Hz,
1
3349. H-NMR (CDCl3) δ: 0.04 (s, 6H), 0.86 (s, 9H), 1.73 (tt, 2H), 7.62–7.67 (m, 1H), 7.68–7.78 (m, 5H), 8.06–8.11 (m, 1H),
J=5.7, 6.2Hz, 2H), 3.23 (q, J=6.2Hz, 2H), 3.68 (t, J=5.7Hz, 8.26–8.33 (m, 1H). 13C-NMR (CDCl3) δ: 1.5, 27.8, 28.6, 32.0,
2H), 5.68 (t, J=5.4Hz, 1H), 7.70–7.74 (m, 2H), 7.81–7.86 (m, 45.1, 45.3, 47.9, 85.5, 124.3, 124.4, 130.1, 131.8, 131.9, 132.8,
1H), 8.10–8.14 (m, 1H). 13C-NMR (CDCl3) δ: −5.5, 18.2, 25.8, 133.2, 133.7, 134.3, 147.5, 147.9, 150.1. HR-MS (ESI-TOF) m/z:
31.8, 41.8, 61.0, 125.1, 131.0, 132.6, 133.4, 133.6, 148.1. HR-MS 735.0262 (Calcd for C23H29IN4O10S2Na+ [M+Na]+: 735.0262).
(ESI-TOF) m/z: 375.1406 (Calcd for C15H27N2O5SSi+ [M+H]+:
375.1404).
Protected Thermospermine 13 To a solution of iodide
11 (4.70g, 6.60mmol) and Ns amide 12 (2.00g, 5.37mmol) in
TBS-Protected 2-Mer 9 To a solution of 6 (30.0g, MeCN (15.7mL) was added Cs2CO3 (4.60g, 14.1mmol) at 0°C
70.9mmol), 8 (19.0g, 50.6mmol) and tetrabutylammonium io- under an argon atmosphere. The mixture was stirred at 60°C
dide (TBAI) (3.70g, 10.1mmol) in MeCN (253mL) was added for 2h. Then the mixture was quenched with saturated aque-

1406
Chem. Pharm. Bull.
Vol. 64, No. 9 (2016)
ous NH4Cl and extracted with EtOAc. The organic layer was phy (n-hexane–EtOAc=1:2) to afford 19a (105mg, quant.)
washed with brine, dried over anhydrous MgSO4, filtered, and as a light yellow amorphous solid. FT-IR (film) cm−1: 584,
concentrated under reduced pressure. The residue was purified 737, 779, 853, 1061, 1126, 1163, 1252, 1269, 1344, 1367, 1439,
1
by silica gel column chromatography (n-hexane–EtOAc=1:1) 1458, 1516, 1545, 1701, 2934, 2976. H-NMR (CDCl3) δ: 1.43
to afford 13 (5.14g, quant.) as a light yellow amorphous solid. (s, 18H), 1.47–1.53 (m, 4H), 1.70 (t, J=6.8Hz, 4H), 3.05–3.15
FT-IR (film) cm−1: 837, 851, 961, 984, 1103, 1123, 1142, 1175, (m, 4H), 3.23–3.33 (m, 8H), 4.83 (brs, 2H), 7.60–7.64 (m,
1258, 1292, 1356, 1377, 1441, 1462, 1539, 1551, 1734, 2858, 2H), 7.66–7.73 (m, 4H), 7.94–8.00 (m, 2H). 13C-NMR (CDCl3)
1
2885, 2932, 2955, 3099. H-NMR (CDCl3) δ: 1.32 (s, 9H), 1.42 δ: 25.0, 28.3, 28.6, 37.4, 45.1, 46.9, 77.3, 124.2, 130.4, 131.8,
(s, 9H), 1.43–1.49 (m, 2H), 1.56 (quint, J=6.8Hz, 2H), 1.86 133.0, 133.6, 147.9, 156.0. HR-MS (ESI-TOF) m/z: 795.2639
(m, 2H), 1.96 (quint, J=7.4Hz, 2H), 3.08 (q, J=6.2Hz, 2H), (Calcd for C32H48N6O12S2Na+ [M+Na]+: 795.2664).
3.27–3.33 (m, 6H), 3.36 (t, J=7.4Hz, 2H), 3.69 (t, J=7.4Hz,
Ns-Protected Spermine on Resin 21a To a solution of
2H), 4.64 (brs, 1H), 7.58–7.65 (m, 2H), 7.65–7.78 (m, 7H), 19a (105mg, 278µmol) in MeOH (1mL) was added SOCl2
7.97–8.04 (m, 2H), 8.23–8.30 (m, 1H). 13C-NMR (CDCl3) δ: (404 µL, 5.56mmol) at 0°C under an argon atmosphere. The
25.4, 27.0, 27.8, 28.4, 28.6, 31.9, 44.7, 45.0, 45.3, 47.3, 85.5, mixture was stirred at room temperature for 2h. Then the
124.16, 124.24, 124.4, 130.1, 131.8, 131.9, 132.8, 133.2, 133.7, reaction mixture was evaporated to give the crude material of
134.3, 147.5, 147.9, 150.1, 156.9. HR-MS (ESI-TOF) m/z: 20a. To a suspension of the freshly prepared resin (1.39mmol)
980.2435 (Calcd for C38H51N7O16S3Na+ [M+Na]+: 980.2447).
and the crude material of 20a in DMF (5mL) were added
Ns-Protected Thermospermine on Resin 16 To a so- DMAP (170mg, 1.39mmol) and DIPEA (726µL, 4.17mmol).
lution of 13 (5.14g, 5.37mmol) in MeOH (33.0mL) was The mixture was slowly stirred for 24h at room temperature.
added SOCl2 (4.09mL, 56.4mmol) at 0°C under an argon Then the mixture was washed with DMF, CH2Cl2, MeOH,
atmosphere. The mixture was stirred at room temperature H2O, DMF, MeOH, CH2Cl2, MeCN, CH2Cl2 and dried in
for 2h. Then the reaction mixture was evaporated to give the vacuo for 2h. For analytical purpose, a small amount of the
crude of 14. To a suspension of the freshly prepared resin 15 resin 21a was treated with 3% TFA in CH2Cl2, the suspen-
(27.2 mmol),16) the crude material of 14 and DMAP (3.33g, sion was filtered and the resin was washed with 10% MeOH
27.2mmol) in DMF (215mL) was added N,N-diisopropylethyl- in CH2Cl2. The filtrate was concentrated in vacuo to afford
amine (DIPEA) (14.2mL, 81.7mmol). The mixture was slowly primary amine 20a as a brown oil. HR-MS (ESI-TOF) m/z:
stirred for 24h at room temperature. Then the mixture was 572.1718 (Calcd for C22H32N6O8S+2 [M]+ 572.1718).
washed with DMF, H2O, 10% MeOH in CH2Cl2, CH2Cl2 and
Spermine (1) To a suspension of the resin 21a in DMF
dried in vacuo for 5h. For analytical purpose, a small amount (5.00mL) were added DBU (831µL, 5.56mmol) and 2-mer-
of the resin 16 was treated with 3% trifluoroacetic acid (TFA) captoethanol (391µL, 5.56mmol) at 0°C under an argon atmo-
in CH2Cl2, the suspension was filtered and the resin was sphere. The mixture was slowly stirred at room temperature
washed with 10% MeOH in CH2Cl2. The filtrate was concen- for 24h. Then the mixture was washed with DMF, CH2Cl2,
trated in vacuo to afford primary amine 14 as a brown oil. MeOH, DMSO, CH2Cl2, MeCN, CH2Cl2 and dried in vacuo
HR-MS (ESI-TOF) m/z: 758.1603 (Calcd for C28H36N7O16S+3 for 2h. The resin was treated with 3% TFA in CH2Cl2, the
[M+H]+: 758.1579).
suspension was filtered and the resin was washed with 10%
Thermospermine (2) To a suspension of the resin 16 MeOH in CH2Cl2. The combined washings were evaporated
in N,N-dimethylformamide (DMF) (180mL) were added and dried in vacuo to provide pale yellow amorphous solid
DBU (23.1mL, 164mmol) and 2-mercaptoethanol (11.5mL, of 1 (30mg, 52% for the 4 steps from 19a) as the TFA salt.
164mmol) at 0°C under an argon atmosphere. The mixture FT-IR (film) cm−1: 1177, 1120, 1670. 1H-NMR (CD3OD) δ:
was slowly stirred at room temperature for 24h. Then the 1.78–1.84 (m, 4H), 2.08 (quint, J=7.9Hz, 4H), 3.03–3.10 (m,
mixture was washed with CH2Cl2, MeOH, dimethyl sulfoxide 8H), 3.31 (t, J=7.9Hz, 4H). 13C-NMR (CD3OD) δ: 24.2, 25.3,
(DMSO), CH2Cl2, MeCN and dried in vacuo for 10h. The 37.8, 45.8, 48.2. HR-MS (ESI-TOF) m/z: 203.2236 (Calcd for
resin was treated with 3% TFA in CH2Cl2, the suspension was C10H27N+4 [M+H]+ 203.2230).
filtered and the resin was washed with 10% MeOH in CH2Cl2.
Protected Norspermine (19b) To a solution of 17 (100mg,
The combined washings were evaporated and dried in vacuo 278µmol) and TBAI (23mg, 63µmol) in MeCN (500µL) were
to afford a pale yellow amorphous solid of 2 (1.1g, quant. added Cs2CO3 (272mg, 835µmol) and 1,3-dibromopropane
for the 4 steps from 13). FT-IR (film) cm−1: 1136, 1163, 1198, (18b) (12.8µL, 126µmol) at 0°C under an argon atmosphere.
1
1670. H-NMR (CD3OD) δ: 1.71–1.83 (m, 4H) 2.02–2.18 (m, The mixture was stirred at 60°C for 2h. Then the mixture was
4H), 2.98 (t, J=7.4Hz, 2H), 3.04–3.10 (m, 4H), 3.11–3.19 (m, quenched with saturated aqueous NH4Cl solution and extract-
6H). 13C-NMR (CD3OD) δ: 24.1, 24.2, 25.3, 25.5, 37.8, 40.0, ed with CH2Cl2. The organic layer was dried over anhydrous
45.8, 46.0, 48.2. HR-MS (ESI-TOF) m/z: 225.2045 (Calcd for MgSO4, filtered, and concentrated under reduced pressure.
C10H26N4Na+ [M+Na]+: 225.2050).
The residue was purified by silica gel column chromatography
Protected Spermine 19a To a solution of 17 (100mg, (n-hexane–EtOAc=1:1) to afford 19b (80.5mg, 85%) as a light
278µmol) and TBAI (23mg, 63µmol) in MeCN (500µL) were yellow amorphous solid. FT-IR (film): 565, 583, 739, 777, 853,
1
added Cs2CO3 (272mg, 835µmol) and 1,4-dibromobutane 1163, 1346, 1368, 1512, 1543, 1690cm−1; H-NMR (CDCl3) δ:
(18a) (15µL, 126µmol) at 0°C under an argon atmosphere. 1.42 (s, 18H), 1.65–1.77 (m, 4H), 1.83 (t, J=7.2Hz, 2H), 3.11
The mixture was stirred at 60°C for 2h. Then the mixture was (q, J=6.3Hz, 4H), 3.26 (t, J=7.4Hz, 4H), 3.31 (t, J=7.2Hz,
quenched with saturated aqueous NH4Cl solution and extract- 4H), 4.90 (brs, 2H), 7.59–7.64 (m, 2H), 7.67–7.77 (m, 4H),
ed with CH2Cl2. The organic layer was dried over anhydrous 7.94–7.99 (m, 2H). 13C-NMR (CDCl3) δ: 27.4, 28.4, 28.6, 37.4,
MgSO4, filtered, and concentrated under reduced pressure. 45.2, 45.6, 79.3, 124.2, 130.6, 131.9, 132.8, 133.7, 148.0, 156.0;
The residue was purified by silica gel column chromatogra- HR-MS (ESI-TOF) m/z: 781.2532 (Calcd for C31H46N6O12S2Na+

Vol. 64, No. 9 (2016)
Chem. Pharm. Bull.
1407
[M+Na]+: 781.2507).
26102736 and the Platform Project for Supporting in Drug
Ns-Protected Norspermine on Resin 21b To a solution Discovery and Life Science Research (Platform for Drug
of 19b (8.10g, 10.7mmol) in MeOH (50mL) was added SOCl2 Discovery, Informatics, and Structural Life Science) from the
(7.75mL, 107mmol) at 0°C under an argon atmosphere. The Ministry of Education, Culture, Sports, Science and Technolo-
mixture was stirred at room temperature for 2h. Then the gy (MEXT) of Japan, and Japan Agency for Medical Research
reaction mixture was evaporated. The crude material of 20b and Development (AMED).
was used for the following reaction without further purifica-
tion. To a suspension of the freshly prepared resin (54.1mmol)
Conflict of Interest The authors declare no conflict of
and the crude material of 20b in DMF (260mL) were added interest.
DMAP (6.52g, 53.4mmol) and DIPEA (27.9mL, 160mmol).
The mixture was slowly stirred for 24h at room temperature.
Then the mixture was washed with DMF, CH2Cl2, MeOH,
H2O, DMF, MeOH, CH2Cl2, MeCN, CH2Cl2 and dried in
vacuo for 10h. For analytical purpose, a small amount of the
resin the crude material of 21b was treated with 3% TFA in
CH2Cl2, the suspension was filtered and the resin was washed
with 10% MeOH in CH2Cl2. The filtrate was concentrated in
vacuo to afford primary amine 20b as a brown oil. HR-MS
(ESI-TOF) m/z: 559.1627 (Calcd for C21H31N6O8S+2 [M+H]+:
559.1639).
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Acknowledgments This work was financially sup-
ported by MEXT/JSPS KAKENHI Grant Numbers 23390007,
Grants-in-Aid for Scientific Research on Priority Areas
(2002).
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