Synthesis and antitumor activity of cis-dichloridoplatinum(II) complexes of 1,1′-biisoquinolines

Article abstract of DOI:10.1016/j.ejmech.2009.09.023

A simple approach to 1,1′,2,2′,3,3′,4,4′-octahydro-1,1′-biisoquinolines is described. Reaction of phenethylamines with oxalyl chloride led to N,N′-bis(phenethyl) oxamides (1). Cyclization of oxamides by using Bischler - Napieralski conditions gave 3,3′,4,4′-tetrahydro-1,1′-biisoquinoline(3) and unusual products 2, 4, 5. Reduction of 3,3′,4,4′-tetrahydro-1,1′-biisoquinolines with sodium boron hydride gave both rac-1,1′,2,2′,3,3′,4,4′-octahydro-1,1′-biisoquinolines(6) and meso-1,1′,2,2′,3,3′,4,4′ -octahydro-1,1′-biisoquinolines(7). Compound 6 was resolved to (1S, 1S′) (8) and (1R, 1R′) (9) furtherly. By treating all the biisoquinolines with K₂PtCl₄ afforded their cis-dichloridoplatinum (II) complexes (12-18). The antitumor activity of these complexes was evaluated.

Full text of DOI:10.1016/j.ejmech.2009.09.023

European Journal of Medicinal Chemistry 45 (2010) 55–62
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and antitumor activity of cis-dichloridoplatinum(II) complexes
of 1,10-biisoquinolines
,
b
c
Chen-Yuan Kuo a , Ming-Jung Wu , Chu-Chieh Lin
*
a Department of Biological Science and Technology, Yung-Ta Institute of Technology and Commerce, 316 JhongShan Road, Pingtung 909, Taiwan, ROC
b Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan, ROC
c Department of Chemistry, National Chung-Hsing University, Taichung 402, Taiwan, ROC
a r t i c l e i n f o
a b s t r a c t
A simple approach to 1,10,2,20,3,30,4,40-octahydro-1,10-biisoquinolines is described. Reaction of phenethyl-
amines with oxalyl chloride led to N,N0-bis(phenethyl) oxamides (1). Cyclization of oxamides by using
Bischler – Napieralski conditions gave 3,30,4,40-tetrahydro-1,10-biisoquinoline(3) and unusual products 2, 4,
5. Reduction of 3,30,4,40-tetrahydro-1,10-biisoquinolines with sodium boron hydride gave both rac-
1,10,2,20,3,30,4,40-octahydro-1,10-biisoquinolines(6) and meso-1,10,2,20,3,30,4,40 -octahydro-1,10-biisoquino-
lines(7). Compound 6 was resolved to (1S, 1S0) (8) and (1R, 1R0) (9) furtherly. By treating all the biisoquinolines
with K2PtCl4 afforded their cis-dichloridoplatinum (II) complexes (12–18). The antitumor activity of these
complexes was evaluated.
Article history:
Received 23 March 2009
Received in revised form
27 July 2009
Accepted 10 September 2009
Available online 16 September 2009
Keywords:
Biisoquinoline
Antitumor activity
Bischler – Napieralski
Ó 2009 Elsevier Masson SAS. All rights reserved.
1. Introduction
a room temperature ionic liquid gave excellent yields [16], but the
costly ionic liquid is a disadvantage. Pt adducts containing the
The adrenergic transmitters adrenaline and noradrenaline are
the natural chemical messengers which on ‘switch on’ the recep-
tors in the adrenergic nervous system. They have an alkylamine
chain linked to a catechol ring (the 1,2-benzenediol ring) [1]. The
backbone appears in isoquinolines which appear in numerous
natural products [2,3], and most of them exhibit different kind of
bioactivity [4–6]. Thus, the synthesis of a variety of isoquinolines,
such as 1-substituented-isoquinolines [7,8] has been wildly
attempted by many researchers. Biisoquinolines, a kind of iso-
quinolines, constituted a new class ligands for the synthesis of
oligocyclic metal(II) complexes. Nielsen [9] afforded epimeric 2,20-
diacetyl-1,10,2,20-tetrahydro-1,10-biisoquinolines by biomolecular
reduction of isoquinoline with zinc-acetic anhydride, and the
1,10,2,20,3,30,4,40-octahydro-1,10-biisoquinoline was obtained via
four steps. That using biisoquinolines as ligands reacted with some
metal ion (Pt, Fe, Ru,Os) to obtain the complexes of metal have been
studied by Kato et al. [10]. Besides, these compounds contain chiral
diamino groups which have numerous applications in asymmetric
synthesis [11,12]. Recently, Judeh and his partners reported that
the 6,60,7,70-tetramethoxy-3,30,4,40-tetrahydro-1,10-biisoquinoline
were synthesized by Bischler – Napieralski cyclization [13–15] in
specially designed chiral diamine ligand, Bip ¼ 2,20-bipiperidine,
are dramatically less fluxional [17]. On the other hand, cisplatin is
a very useful antitumor agent for the treatment of testicular and
ovarian cancers [18,19]. Since the antitumor activity of cisplatin was
reported, various platinum complexes have been synthesized and
tested for the antitumor activity [13]. In the present paper, we used
the simple double Bischler – Napieralski cyclization followed by
reduction of the resulting bis-imine to synthesize 1,10,2,20,3,30,4,40-
octahydro-1,10-biisoquinolines and investigated all possible
products in different conditions. Furthermore, we synthesized
cis-dichloridoplatinum(II) complexes of 1,10,2,20,3,30,4,40-octahy-
dro-1,10-biisoquinolines (OHBIIQs) and their antitumor activity of
these complexes was evaluated.
2. Chemistry
The treatment of 3,4-dimethoxyphenethylamine with oxalyl
chloride gave N,N0-Bis(3,4-dimethoxyphenethyl)oxamide 1 in good
yield. The most directroute to3 (2,4,5 also gave) would be via double
Bischler – Napieralski cyclization from compound 1. Treatment of
bis-imine 3 with NaBH4 gave a mixture of diastereomers 6 and 7.
Rac-6 were resolved to 8 (1S, 1S0) and 9 (1R, 1R0). By treating all the
biisoquinolines with K2PtCl4 afforded their cis-dichloridoplatinum
(II) complexes (12–18).
* Corresponding author. Tel.: þ886 4 2840412x718; fax: þ886 8 7227024.
E-mail address: cchlin@mail.nchu.edu.tw (C.-Y. Kuo).
0223-5234/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2009.09.023

56
C.-Y. Kuo et al. / European Journal of Medicinal Chemistry 45 (2010) 55–62
MeO
MeO
MeO
O
O
O
Py.
+
Cl
Cl
(
)
2
HN
NH2
MeO
1
MeO
MeO
MeO
MeO
MeO
N
N
POCl3
O
N
MeO
)
HN
2
O
MeO
MeO
MeO
MeO
NH
3
2
MeO
MeO
MeO
MeO
N
N
MeO
MeO
N
MeO
MeO
NH
5
4
Scheme 1.
3. Pharmacology
[20]. All of these compounds exhibited activity against MCF-7 cell
line and showed good activity. In order to understand the relation-
ship between the structure of ligands of the complexes and the biological
activity further, we synthesized a series of cis-dichloridoplatinum(II)
Fifteen cis-dichloridoplatinum complexes have been synthesized
by treatment of 1-(2-aminophenyl)-1,2,3,4 -tetrahydroisoquinolines
(THIQs) with K2PtCl4. The antitumor activity of these compounds
was examined against four different human tumor cell lines. Their
structure-activity relationships for antitumor activity were reported
Table 2
Reaction of 6,60,7,70-tetramethoxy-3,30,4,40-tetrahydro-1,10-biisoquinoline (3) with
reducing agents.
Table 1
Entry
Reducing agent
Temp (ꢀC)
Yields [%]
6/7 Ratio
Reaction of N,N0-bis(3,4-dimethoxyphenethyl)oxamide with POCl3.
1
2
3
4
5
6
NaBH4
NaBH4
NaBH3CN
NaBH3CN
LiAlH4
r.ta
55a
r.tb
55b
r.tc
35c
68
76
75
82
0
18:50
19:67
75:0
82:0
0:0
Entry
Method
Temp (ꢀC)
Time (h)
Yields (%)
2
3
4
5
1
2
3
4
A1
A2
A2
A2
111
80
80
5–6
5–6
12–18
5–6
5
15
6
18
75
50
–
34
–
10
–
17
–
8
LiAlH4
0
0:0
a
All reactions were carried out using General Procedure C.
All reactions were carried out using General Procedure D.
Reactions were carried out using General Procedure C. No products were
70
84
–
b
c
Method A1: Treated with POCl3 and toluene.
Method A2: Treated with POCl3 and CH3CN.
obtained.
H
H
MeO
MeO
MeO
MeO
N
N
N
MeO
MeO
MeO
MeO
NH
3
4
-H2
MeO
MeO
MeO
MeO
MeO
N
NH
N
NH
NH
-H2
MeO
MeO
MeO
MeO
MeO
MeO
MeO
N
5
Scheme 2.

C.-Y. Kuo et al. / European Journal of Medicinal Chemistry 45 (2010) 55–62
57
M
S
NaBH CN
MeO
MeO
M
3
N
S
N
H
NH
N
H
NH
H
NH
N
H
NH
NaBH3CN
NaBH4
MeO
MeO
3
Ar
H-
Ar
Ar
Ar
L
L
M
MeO
MeO
H-
S
H
M
S
N
NH
NH
NH
H
NH
H
NH
CH3OH
H
NH
H
NaBH4
MeO
MeO
N
Ar
Ar
Ar
Ar
Ar
Ar
L
L
( Rac Major)
H
MeO
MeO
Fig. 2. Treating 3 with sodium cyanoborohydride.
CH3OH
H
NH
NH
NH
NH
product 6. The results are summarized in Table 2. Interestingly,
replacement of the NaBH4 with LiAlH4 afforded no 6 and 7. For the
additions to the carbon-nitrogen double bond of imine (3) con-
MeO
MeO
Ar
Ar
taining an asymmetric
a-carbon, Cram’s rule [21] may predict
( Meso Major)
which diastereomer will predominate. The rule indicates that the
presence of an asymmetric center in a molecule induces the
formation of an asymmetric center adjacent to it based on steric
hindrance. If the molecule is observed along its axis, it may be
represented as in Fig. 1, where S, M, and L stand for small, medium,
and large, respectively. The nitrogen of the imino orients itself
between the small- and the medium-sized groups. The rule is that
the incoming group preferentially attacks on the side of plan
containing the small group. By the rule, it can be predicted that
meso- will be formed in larger amounts than rac-. Treating 3 with
sodium borohydride under different reaction conditions, gave
compounds 6 (rac-) and 7 (meso-) were obtained in 1:3 ratios as
Table 2 shown, respectively. The results follow the Cram’s rule
(Fig. 1). In contrasting, treating 3 with sodium cyanoborohydride
gave compound 6 (rac-) only. That is because the sodium cyano-
borohydride interacted with C]N and N-H groups that the
incoming group (Hꢁ) preferentially attacks on the other side
(Fig. 2). Rac-6 were resolved to (1S, 1S0) and (1R, 1R0) as outline in
Fig. 1. Treating 3 with sodium borohydride.
complexes
of
1,10,2,20,3,30,4,40-octahydro-1,10-biisoquinolines
(OHBIIQs) and evaluated their antitumor activity in this paper.
4. Results and discussions
The most direct route to 3 would be via double Bischler –
Napieralski cyclization from compound 1 (Scheme 1). However,
the products were contaminated with an intensely red impurity
that could not be easily removed by chromatography. The results
are summarized in Table 1. Treatment of compound 1 with 5 equiv
of POCl3 at 111 ꢀC for 6 h afforded a 18:5:34:17 mixtures of prod-
ucts, 3, 2, 4, and 5 (entry 1), which were separated by column
chromatography. A better yield of 3 (75%) was obtained if
compound 1 was treated with 5 equiv of POCl3 at 80 ꢀC for 6 h
(entry 2). However, treatment with 5 equiv of POCl3 at 70 ꢀC for 6 h
afforded compound 2 in high yield (84%) (entry 4). The relation-
ship among 3, 4 and 5 are shown in Scheme 2. Treatment of bis-
imine 3 with NaBH4 gave a mixture of diastereomers 6 and 7 in 18%
and 50% (19% and 67%) yields, respectively. However, replacement
of the NaBH4 with NaBH3CN afforded only the rac reduction
Scheme 3 [22]. Treatment of Rac-6 with D-(þ)-
a-bromo camphor-
p
-sulfonic acid ammonium salt afforded the (1S, 1S0)-1,10–biiso-
quino line sulfonic acid salt. The sulfonic acid salt was alkalinized
then. Removal of drying agent and solvent gave solid, and the solid
was recrystallised from ethanol to give (1S, 1S0) 8. Similarly,
replacement of the D-(þ)-
a
-bromo camphor-p-sulfonic acid
MeO
MeO
MeO
N
NH
NH
NaBH4
MeOH
NH
MeO
MeO
MeO
MeO
MeO
MeO
+
N
NH
MeO
MeO
MeO
3
7
( meso)
6
(d, l )
Rac
1. D-(+) or (-)-bromocamphor
sulfonic acid ammonium salt
2.NaOH
8 (S,S) + 9 (R,R)
Scheme 3.

58
C.-Y. Kuo et al. / European Journal of Medicinal Chemistry 45 (2010) 55–62
HO
HO
HO
NH
NH
NH
NH
48% HBr
HO
HO
6, 7
2HBr
2HBr
+
HO
HO
HO
11
10
Scheme 4.
MeO
MeO
K2PtCl4
N
N
NH
NH
3, 6, 7, 8,
9, 10, 11
MeO
MeO
MeO
MeO
PtCl2
PtCl2
MeO
MeO
MeO
MeO
13 (dl)
12
MeO
NH
NH
NH
MeO
MeO
PtCl2
MeO
MeO
MeO
MeO
PtCl2
PtCl2
NH
NH
NH
MeO
MeO
HO
MeO
14 (meso)
15 (S, S)
16 (R, R)
HO
NH
NH
NH
HO
HO
HO
HO
PtCl2
PtCl2
NH
HO
HO
17
18
Scheme 5.
ammonium salt with D-(-)-
a
- bromocamphor-
p
-sulfonic acid
HeLa and MCF-7 cell lines. The results are summarized in Table 3.
As shown in Table 3, all these compounds exhibited good activity
against MCF-7 cell lines, except compound 12 which are planar
due to the C]N bond. D’Ocon et al. [23] reported that the planarity
ammonium salt, using the same process, afforded (1R, 1R0) 9.
Converting methyl ether to hydroxyl groups will usually
strengthen hydrogen bonding. The obvious explanation is that the
proton of the hydroxyl group is involved in the hydrogen bond to
the receptor and if it is removed the hydrogen bonding is lost.
According to this reason, we converted compounds 6 and 7 to the
compounds (10, 11), which may strengthen the biological activity.
The title compounds were prepared as Scheme 4 shown. The BIIQs
(3,6,7,8,9) and equimolar amounts of K2PtCl4 were dissolved in
0.1 M HCl at 60–65 ꢀC. To this stirring solution was added with
0.1 N NaOH to neutrality at 60–65 ꢀC. [BIIQs] dichlorido-
platinums(II) (12–16) were obtained in good yields. On the other
hand, The BIIQs (10, 11) were dissolved in water at 60–65 ꢀC. To this
stirring solution was added with 0.1 N NaOH to neutrality at
60–65 ꢀC. [BIIQs] dichloridoplatinums(II) (17,18) were obtained in
good yields (Scheme 5). Due to Cl-DMSO ligand exchange [19], the
of the isoquinoline ring decreases the affinity for
eceptor, whereas the more flexible THIQ ring increases the inter-
action with the 1-adrenoreceptor site. In our report, compound
a1-adrenor-
a
12, containing planar structure, exhibited similar result as D’Ocon
et al. reported in against MCF-7 cell lines.
Table 3
Cytotoxicity of compounds 12–18 against Human Tumor Cells (IC50 ꢂ SD,
mM).
Compound
Hepa59T/VGHa
WiDrb
HeLac
MCF-7d
12
13
14
15
16
17
18
cisplatin
(-)
(-)
(-)
(-)
(-)
24.31 ꢂ 0.67
10.12 ꢂ 0.17
8.63 ꢂ 0.75
5.37 ꢂ 0.32
5.19 ꢂ 0.44
7.83 ꢂ 0.22
8.14 ꢂ 0.37
7.76 ꢂ 0.30
29.05 ꢂ 0.73
26.50 ꢂ 1.09
29.84 ꢂ 1.15
(-)
27.55 ꢂ 0.95
22.23 ꢂ 1.39
16.48 ꢂ 0.61
8.84 ꢂ 0.52
(-)
(-)
target products showed multiple sets of signals in 1H NMR and 13
C
29.94 ꢂ 1.07
21.95 ꢂ 0.32
(-)
25.98 ꢂ 0.40
NMR spectra, taken in DMSO (d6) that made assignment more
(-)
(-)
difficult. The 1H NMR spectroscopic data of compound 13 and 14
23.67 ꢂ 0.84
show the presence of multiple sets singlet signals at
d 4.37–4.88
3.52 ꢂ 0.33
12.06 ꢂ 0.41
corresponding to the methine (CH) group at the 1,10 position.
Elemental analysis confirmed the structure of the target products
further. The cytotoxicities of the series of cis-dichloridoplatinum
complexes (12–18) were examined with Hepa59T/VGH, WiDr,
a
Human liver carcinoma.
Human colon adenocarcinoma.
Human cervical epitheloid carcinoma.
Human breast adenocarcinoma (-) IC50 > 50 mM.
b
c
d

C.-Y. Kuo et al. / European Journal of Medicinal Chemistry 45 (2010) 55–62
59
5. Conclusion
layers were separated. The organic phase was washed with saturated
Na2CO3 solution (3 ꢃ10 mL), 10 mL of water, and 10 mL of brine and
dried (MgSO4). After filtration and evaporation, the residue was
recrystallized from ethyl alcohol to give 3.
Double Bischler – Napieralski cyclization of compound 1 afforded
a mixture of products, 3, 2, 4, and 5. Treatment of bis-imine with
NaBH4 gave a mixture of diastereomers rac and meso. However,
replacement of the NaBH4 with NaBH3CN afforded only the rac
reduction product. Seven platinum complexes of BIIQ have been
synthesized. Most of these compounds exhibited good activity
against MCF-7 cell lines.
6.3.2. General procedure B (method A2)
To a stirring solution of N,N0-diphenethyloxamide (12.9 mmol) in
dry CH3CN (80 mL) was added POCl3 (32 mmol) dropwise, and the
stirring was continued for 1 h at room temperature. The resulting
mixture was heated to reflux and stirred for approximately 5–12 h.
After removal of the solvent in vacuo, CHCl3 (50 mL) and H2O (50 mL)
were added, and the aqueous phase was adjusted with aqueous 10 N
NaOH to pH 12. The organic layer waswashed with saturated aqueous
NaHCO3 (3 ꢃ100 mL), dried over anhydrous Na2SO4, and the solvent
was removed in vacuo. The crude product was purified by column
chromatography using silica gel (EtOAc/n-hexane, 2:1) and then
recrystallization of the products from ethanol, afforded compounds
2,3,4,5.
6. Experimental
6.1. Chemistry
All melting points were determined on a Digital MEL-TEMP
melting point apparatus, and are uncorrected. Infrared spectra were
recorded on a Digilab FTIR spectrophotometer. The 1H and 13C NMR
spectrawere recorded at 400 and 100 MHz, respectively. High-resolution
mass spectra were recorded on a double focusing magnetic sector
mass spectrometer using EI at 70 eV. All reactions were monitored
by analytical TLC (silica gel 60 F254, Merck). The residues were
purified by flash chromatography (230–400 mesh). Elemental
analyses were recorded using a Heraeus CHNO-Rapid elemental
analyzer.
6.3.2.1. 1-(3,4-dimethoxyphenethyl carbamoyl) 6,7-dimethoxy-3,4
–dihydro isoquinoline (2). White powders, mp 118–120 ꢀC, 1H NMR
(400 MHz, CDCl3) d 7.96 (1H, s, H-8), 7.63 (1H, br, NH), 6.76–6.80 (3H,
m, H-10,50,60), 6.67 (1H, s, H-5), 3.91 (3H, s, OMe), 3.90 (3H, s, OMe),
3.87 (3H, s, OMe), 3.86 (3H, s, OMe), 3.72 (2H, t, J ¼ 7.6 Hz, ]NCH2),
3.62 (2H, q, J ¼ 7.2 Hz, NHCH2), 2.85 (2H, t, J ¼ 7.2 Hz, NHCH2 CH2),
6.2. N,N0-Bis(3,4-dimethoxyphenethyl)oxamide (1)
2.64 (2H, t, J ¼ 7.6 Hz, ]NCH2CH2); 13C NMR (100 MHz, CDCl3)
d164.2
(C]O),158.8 (C]N),151.6 (C-6),148.8 (C-7),147.9 (C-40),147.3 (C-30),
132.0 (C-4a), 131.4 (C-8a), 120.6 (C-8), 119.0 (C-1), 112.0 (C-5), 111.9
(C-60), 111.3 (C-50), 109.8 (C-20), Anal. Calcd for C22H24N2O4: C, 69.46;
H, 6.36; N, 7.36. Found: C, 69.71; H, 6.41; N, 7.25.
6.2.1. General procedure A
Oxalyl chloride (7.25 g, 57 mmol) was dissolved in dry benzene
(30 mL) and added dropwise to a stirred solution of 3,4-dime-
thoxyphenethylamine (8.12 g, 44 mmol) and pyridine (4.53 g,
57 mmol) in dry benzene (100 mL). The mixture was continuously
stirred at room temperature overnight and then poured into water
(200 mL). Filterated the solution and the solid were washed with
1.0 N HCl (100 mL), 1.0 N NaOH (100 mL), and water (100 mL).
Recrystallization of the crude product from EtOAc afforded 1
(5.91 g). The mother layer was evaporated and the residue was
recrystallized from EtOAc to afford white crystals 1 (1.54 g). Totally,
compound 1 was obtained in 83% yield (7.45 g).
6.3.2.2. 6,60,7,70-tetramethoxy-3,30,4,40-tetrahydro-1,10-biisoquino-
line (3). Red powders, m.p. 198–200 ꢀC, 1H NMR (400 MHz, CDCl3)
d
6.84 (2H, s, H-8,80) 6.72 (2H, s, H-5,50) 3.92 (6H, s, OMe-C7,70) 3.91
(4H, t, J ¼ 7.6 Hz, H-3) 3.71 (6H, s, OMe-C6,60), 2.80 (4H, t, J ¼ 7.6 Hz,
H-4); 13C NMR (100 MHz, CDCl3), 164.6 (C]N), 51.6 (C-6,60), 147.4
d
(C-7,70), 131.5 (4a,4a0), 120.8 (C-8a,8a0), 110.6 (5,50), 110.3 (8,80), 56.0
(OMe), 55.9 (OMe) 47.1 (C-3,30), 25.6 (C-4,40); HREIMS m/z (%) ¼ 380
(100) [Mþ], Anal. Calcd for C22H24N2O4,0.5 H2O: C, 67.85; H, 6.47; N,
7.19. Found: C, 68.51; H, 6.63; N, 6.69.
M.p. 170–171 ꢀC, 1H NMR (400 MHz, CDCl3)
6.71–6.75 (2H, m) 6.8 (1H, d) 3.87 (3H, s) 3.86 (3H, s) 3.54 (2H, q)
2.80 (2H, t); 13C NMR (100 MHz, CDCl3, ppm)
159.6 (C]O), 149.1
(C-3), 147.8 (C-4), 130.5 (C-1), 120.6 (C-6), 111.7 (C-2), 111.4 (C-5),
55.9 (OCH3), 55.8 (OCH3), 40.9 (CH2N), 35.0 (CH2CH2N). EI-MS m/z
(%) ¼ 416 (100) [Mþ], Anal. Calcd for C22H28N2O6: C, 63.45; H, 6.78;
N, 6.73. Found: C, 62.74; H, 6.68; N, 6.79.
d 7.51 (1H, br s)
d
6.3.2.3. 6,60,7,70-tetramethoxy-3,4-dihy dro-2H,40H-[1,10]biisoquino-
linylidene (4). Brown liquid, 1H NMR (400 MHz, CDCl3)
d 7.17 (1H, s,
H-8) 6.94 (1H, s, H-80) 6.70 (1H, s, H-5) 6.66 (2H, m, H-3 and H-20)
6.63 (1H, s, H-50) 4.03 (2H, s, H-4) 3.85 (3H, s, OCH3-7) 3.80 (3H, s,
OCH3-6) 3.76 (3H, s, OCH3-70) 3.75 (3H, s, OCH3-60) 3.77 (2H, q,
J ¼ 6.8 Hz, H-30) 2.83 (2H, t, J ¼ 6.8 Hz, H-40); 13C NMR (100 MHz,
6.3. 6,60,7,70-tetramethoxy-3,30,4,40 tetrahydro-1,10-biisoquinoline
and their relative compounds
CDCl3) d
148.9 (C-6), 148.2 (C-7), 147.9 (C-60), 147.5 (C-70), 145.4 (C-3
C]N), 129.4 (C-1), 129.3 (C-10), 122.5 (C-4a), 120.9 (C-40a), 119.9 (C-
8a), 119.9 (C-80a), 111.2 (C-80), 111.1, (C-8), 110.9 (C-50), 105.8 (C-5),
55.8 (OMe), 55.7 (OMe), 55.6 (OMe),þ40.7 (C-30), 033.0 (C-4), 25.6 (C-
40); HREIMS m/z(%) ¼ 380 (100) [M ], 379 (34) [Mþ-H], 365 (30)
[Mþ- CH3], 349 [Mþ-H-2CH3], Anal. Calcd for C22H24N2O4: C, 69.46;
H, 6.36; N, 7.36. Found: C, 69.33; H, 6.31; N, 7.41.
6.3.1. General procedure B (method A1)
A
mixture of N,N0-diphenethyloxamide (6.7 mmol), POCl3
(33 mmol), and dry toluene (100 mL) was refluxed for 3 h. The
cooled mixture was poured into ice-water (100 mL) and stirred for
2 h. The organic layer was discarded. The water layer and precipitates
were then basified with 2 N NaOH (100 mL) and extracted with
CH2Cl2 (50 mL ꢃ 3). The extracts were washed with water (100 mL),
dried (Na2SO4), and evaporated to give product as a solid. The crude
product was purified by column chromatography using silica gel
(EtOAc/n-hexane, 2:1) and then recrystallization of the products
from ethanol, afforded compounds 2,3,4,5. The products were
contaminated with an intensely red impurity. The red impurity was
separated through a silica gel pad (column 20 ꢃ 100 mm) using
EtOAc-AcOH-MeOH 8:1:1. The resulting mixture was diluted with
50 mL of CH2Cl2 and 50 mL of water, basified with 2 N NaOH, and the
6.3.2.4. 6,60,7,70-tetramethoxy-30,40- dihydro-1,10-biisoquinoline
(5). Yellowish powders, m.p. 184–186 ꢀC, 1H NMR (400 MHz, CDCl3)
d
8.45 (1H, d, J ¼ 7.0 Hz, H-3) 7.56 (1H, d, J ¼ 7.0 Hz, H-4) 7.42 (1H, s,
H-8) 7.11 (1H, s, H-5) 6.78 (1H, s, H-80) 6.51 (1H, s, H-50) 4.03 (3H, s, H-
7) 4.03 (2H, t, J ¼ 7.6 Hz, H-30) 3.93 (3H, s, H-60) 3.87 (3H, s, H-70) 3.56
(3H, s, H-60) 2.89 (2H, t, J ¼ 7.6 Hz, H-40); 13C NMR (100 MHz, CDCl3)
d
165.4 (N]C0-1), 154.8 (N]C-10), 152.9 (C-6), 151.5 (C-7), 150.2 (C-
60), 147.4 (C-70), 140.7 (C-3), 133.9 (C-4), 131.7 (C-4a), 123.1 (C-8a),
122.0 (C-40a),119.9 (C-8a0),111.2 (C-80),110.3 (C-8),104.8 (C-50),104.7
(C-5), 56.0 (OMe), 55.9 (OMe), 55.7 (OMe), 47.6 (C-3,30), 25.7 (C-4,40);

60
C.-Y. Kuo et al. / European Journal of Medicinal Chemistry 45 (2010) 55–62
HREIMS m/z (%) ¼ 378 (36) [Mþ], 377 (19) [Mþ-H], 363 (100) [Mþ-
CH3], 347 (99) [Mþ-H-2CH3], Anal. Calcd for C22H22N2O4 1/2H2O: C,
68.20; H, 5.98; N, 7.23. Found: C, 68.09; H, 5.83; N, 7.14.
White solid, m.p. 130–133 ꢀC, 1H NMR (400 MHz, CDCl3)
d 6.73
6.65 (2H, ss, H-8,80) 6.37 6.35 (2H, ss, H-5,50), 4.76 4.73 (2H, ss, H-
1,10), 4.47 (1H, d, J ¼ 4.4 Hz, CHBr), 3.85 (6H, s, 2OMe), 3.71 (6H, s,
2OMe), 3.51–3.54 (2H, m, H-3e,30e), 3.09–3.23 (2H, m, H-3a, 3a0),
2.83–3.02 (6H, m, H-4, CHCH2), 2.58 (1H, d, J ¼ 14.0 Hz, CHCHBr),
1.98 (2H, m, CHCH2), 1.56 (1H, m, CCH2-e), 1.36 (1H, m, CCH2-a),1.06
6.4. 6,60,7,70-tetramethoxy-1,10,2,20,3, 30,4,40-octahydro-1,10-
biisoquinolines (6,7)
(CH3), 0.88 (CH3); 13C NMR (100 MHz, CDCl3)
d 211.9 (C]O), 149.0
(C-7,70), 147.7 (C-6,60), 127.0 126.9(C-4a,4a0), 121(C-8a,8a0), 111.5
111.4 (C-5,50), 110.7(C-8,80), 59.5 (C-1), 57.6 (CC]O), 56.0
(4 ꢃ OMe), 53.9 (O3SCH2), 53.4 (CHBr), 47.2 (C), 46.8 (CHCHBr),
40.3 (C-3,30), 30.1 (CCH2), 26.8 (C-4,40), 22.0 (CHCH2), 17.4 (CH3),
9.7 (CH3);
6.4.1. General procedure C
To a solution of 6,60,7,70-tetramethoxy- 3,30,4,40-tetrahydro-1,10-
biisoquinolines (3) (4.2 mmol) in methanol (80 mL) NaBH4
(21 mmol) was added in portions, the mixture was continuously
stirred at room temperature for approximately 4 h. After removal of
the solvent in vacuo, CH2Cl2 (50 mL) and H2O (50 mL) were added.
The aqueous phase was extracted with CH2Cl2 (20 mL ꢃ 2), and the
combined organic layers were washed with water (30 mL ꢃ 2) and
dried over anhydrous MgSO4. The solvent was evaporated in vacuo.
The crude products were separated by a flash column (EtOAc/n-
Hexane 2:1), afforded crystals 6, 7.
6.5.2. (1S, 1S0)-6,60,7,70-tetramethoxy -1,10,2,203,30,4,40-octahydro-
1,10 –biisoquinline (8)
D-(þ)-
a-bromocamphor-p- sulfonic acid salt (0.44 mmol) was
stirred in CH2Cl2 (20 mL) and 5 M NaOH (20 mL) at rt for 2 h. The
organic layer was separated and dried over NaOH (pellets).
Removal of drying agent and solvent gave solid, recrystallization
from ethanol to give 0the title compound in 77% yield.
6.4.1.1. Rac-6,60,7,70-Tetramethoxy-1,10, 2,20,3,30,4,40-octahydro-1,10-
biisoquinline (6). The title compound was obtained as a White
powders in 56% yield from 3 following procedures C; mp 174–
White solid, mp 182–185 ꢀC, 1H NMR (400 MHz, CDCl3)
d 6.74
(2H, s, H-8,80) 6.60 (2H, s, H-5,50), 4.52 (2H, s, H-1,10), 3.85 (6H, s,
2OMe), 3.84 (6H, s, 2OMe), 3.17–3.23 (2H, m, H-3e,30e), 2.80–2.90
(4H, m, H- 3a, 3a0, H-4e, 4e0), 2.55–2.60 (2H, m, H-4a, 4a0), 2.07 (2H,
179 ꢀC, 1H NMR (400 MHz, CDCl3)
d
6.75 (2H, s, H-8,80) 6.60 (2H, s,
H-5,50), 4.53 (2H, s, H-1,10), 3.86 (6H, s, 2OMe), 3.85 (6H, s, 2OMe),
3.17–3.22 (2H, m, H-3e,30e), 2.79–2.90 (4H, m, H- 3a, 3a0, H-4e, 4e0),
2.54–2.60 (2H, m, H-4a, 4a0), 2.05 (2H, br, 2 NH); 13C NMR (100 MHz,
br, 2 NH); 13C NMR (100 MHz, CDCl3)
d
147.7 147.5 (C-6,60,7,70),
129.3 (4a,4a0), 127.0 (C-8a,8a0), 111.9 (5,50), 108.6 (8,80), 59.5 (C-1),
56.0 (OMe), 55.9 (OMe) 42.3 (C-3,30), 29.5 (C-4,40); HREIMS m/z
(%) ¼ 384 (0) [Mþ], 192 (100) [Mþ/2], 176 (20) [Mþ/2- H-CH3], Anal.
Calcd for C22H28N2O4: C, 68.73; H, 7.34; N, 7.29. Found: C, 68.55; H,
7.23; N, 7.35.
CDCl3) d
147.6 147.5 (C-6,60,7,70), 129.4 (4a,4a0), 127.1 (C-8a,8a0), 111.9
(5,50), 108.7 (8,80), 59.4 (C-1), 56.0 (OMe), 55.8 (OMe) 42.4þ(C-3,30),
29.5 (C-4,40); HREIMS m/z(%) ¼ 384 (0) [Mþ], 192 (100) [M /2], 176
(20) [Mþ/2- H-CH3], Anal. Calcd for C22H28N2O4: C, 68.73; H, 7.34; N,
7.29. Found: C, 68.81; H, 7.20; N, 7.01.
6.5.3. (1R, 1R0)-6,60,7,70-tetramethoxy -1,10,2,203,30,4,40-octahydro-
6.4.1.2. Meso-6,60,7,70-Tetramethoxy-1,10,2,20,3,30,4,40-octahydro-1,10-
biisoquinoline (7). The title compound was obtained as a white
powders in 18% yield from 3 following procedures C; mp 165–168 ꢀC
1,10–biisoquinoline D-(-)-
a-bromocamphor-p- sulfonic acid salt
Rac-6,60,7,70-tetramethoxy-1,10,2,203,30,4,40-octahydro-1,10-bii-
soquinoline (0.24 g, 0.625 mmol) and D-(-)-bromo camphor-
sulfonic acid ammonium salt (0.22 g, 0.62 mmol) were recrys-
tallized from ethanol (5 mL) to give the title compound in 89%
yield.
(lip. 169–171), 1H NMR (400 MHz, CDCl3)
d
6.55 (2H, s, H-8,80) 6.41
(2H, s, H-5,50), 4.58 (2H, s, H-1,10), 3.83 (6H, s, 2OMe), 3.56 (6H, s,
2OMe), 3.08–3.14 (2H, m, H-3e,30e), 2.83–2.90 (2H, m, H-3a),
2.63–2.70 (2H, m, H-4e), 2.54–2.59 (2H, m, H-4a), 2.04 (2H, br, 2 NH);
White solid, m.p. 135–137 ꢀC, 1H NMR (400 MHz, CDCl3)
d 6.75
13C NMR (100 MHz, CDCl3)
d
147.4 147.3 (C-6,60,7,70), 129.0 (4a,4a0),
6.66 (2H, ss, H-8,80) 6.38 6.35 (2H, ss, H-5,50), 4.77 4.74 (2H, ss, H-
1,10), 4.48 (1H, d, J ¼ 4.4 Hz, CHBr), 3.85 (6H, s, 2OMe), 3.72 (6H, s,
2OMe), 3.51–3.55 (2H, m, H-3e,30e), 3.10–3.23 (2H, m, H-3a, 3a0),
2.83–3.04 (6H, m, H-4, CHCH2), 2.59 (1H, d, J ¼ 14.0 Hz, CHCHBr),
1.99 (2H, m, CHCH2), 1.55 (1H, m, CCH2-e), 1.36 (1H, m, CCH2-a),1.05
127.6o (C-8a,8a0),111.8 (5,50),109.1 (8,80), 60.1 (C-1), 55.8 (OMe), 55.5
(OMe) 42.2 (C-3,30), 29.7 (C-4,40); HREIMS m/z(%) ¼ 384 (0) [Mþ],192
(100) [Mþ/2], 176 (20) [Mþ/2- H-CH3], Anal. Calcd for C22H28N2O4: C,
68.73; H, 7.34; N, 7.29. Found: C, 68.35; H, 7.13; N, 6.97.
(CH3), 0.89 (CH3); 13C NMR (100 MHz, CDCl3)
d 211.1 (C]O), 149.2
(C-7,70), 147.8 (C-6,60), 127.1 126.9(C-4a,4a0), 121.1 (C-8a,8a0), 111.5
111.4 (C-5,50), 110.7(C-8,80), 59.5 (C-1), 57.6 (CC]O), 56.0
(4 ꢃ OMe), 53.7 (O3SCH2), 53.4 (CHBr), 47.2 (C), 46.9 (CHCHBr),
40.4 (C-3,30), 30.3 (CCH2), 26.6 (C-4,40), 22.0 (CHCH2), 17.4 (CH3),
9.8 (CH3);
6.4.2. General procedure D
To
a
solution of 3,30,4,40-tetrahydro-1,10-biisoquinolines
(4.2 mmol) in methanol (80 mL), 3 N HCl (3 mL) and NaBH3CN
(21 mmol) was added in portions, the mixture was continuously
stirred at room temperature for approximately 4 h. After removal of
the solventinvacuo, CH2Cl2 (50 mL)and H2O(50 mL)wereadded,and
the aqueous phase was adjusted with aqueous 10 N NaOH to pH 12.
The organic layer was washed with saturated aqueous NaHCO3
(3 ꢃ100 mL), dried over anhydrous Na2SO4, and the solvent was
removed invacuo.Recrystallizationofthecrudeproductfromethanol,
afforded crystal 7 (81%).
6.5.4. (1R, 1R0)-6,60,7,70-tetramethoxy -1,10,2,203,30,4,40-octahydro-
1,10 –biisoquinoline (9)
The title compound was obtained as a white powders in 82%
yield in a similar procedure for the preparation of 8; m.p. 180–
182 ꢀC, 1H NMR (400 MHz, CDCl3) 6.75 (2H, s, H-8,80) 6.61 (2H, s,
d
H-5,50), 4.54 (2H, s, H-1,10), 3.87 (6H, s, 2OMe), 3.85 (6H, s, 2OMe),
3.16–3.22 (2H, m, H-3e,30e), 2.79–2.91 (4H, m, H- 3a, 3a0, H-4e,
4e0), 2.54–2.61 (2H, m, H-4a, 4a0), 2.06 (2H, br, 2 NH); 13C NMR
6.5. (1S, 1S0) and (1R, 1R0) (-6,60,7,70-tetramethoxy-1,10,2,203,30,4,40-
octahydro-1,10-biisoquinoline)
(100 MHz, CDCl3)
d
147.6 147.4 (C-6,60,7,70), 129.3 (4a,4a0), 127.3
6.5.1. (1S, 1S0)-6,60,7,70-tetramethoxy- 1,10,2,203,30,4,40-octahydro-
(C-8a,8a0), 111.9 (5,50), 108.7 (8,80), 59.3 (C-1), 55.9 (OMe), 55.8
(OMe) 42.6 (C-3,30), 29.5 (C-4,40); HREIMS m/z(%) ¼ 384 (0) [Mþ],
192 (100) [Mþ/2], 176 (20) [Mþ/2- H-CH3], Anal. Calcd for
C22H28N2O4: C, 68.73; H, 7.34; N, 7.29. Found: C, 69.01; H, 7.40; N,
7.32.
1,10–biiso- quinline D-(þ)-
a
-bromocamphor-
p
- sulfonic acid salt
Rac-6 (0.24 g, 0.625 mmol) and D-(þ)-
a
-bromocamphor-p-
sulfonic acid ammonium salt (0.21 g, 0.625 mmol) were recrystal-
lized from ethanol (5 mL) to give the title compound in 82% yield.

C.-Y. Kuo et al. / European Journal of Medicinal Chemistry 45 (2010) 55–62
61
6.6. 6,60,7,70-Tetrahydroxy-1,10,2,20, 3,30,4,40-octahydro-1,10-
for C22H28N2O4PtCl2,C2H5OH: C, 41.39; H, 4.92; N, 4.02. Found: C,
biisoquinoline Dihydrobromides (10,11)
41.34; H, 5.17; N, 4.26.
6.6.1. General procedure E
6.7.1.4. (1S, 1S0)-6,60,7,70-tetramethoxy -1,10,2,203,30,4,40-octahydro-
A suspension of the, 60,7,70-tetrameth oxy-1,10,2,20,3,30,4,40-
octahydro-1,10-biisoquinoline (10 mmol) in 48% aqueous hydro-
bromic acid (3 mL) was refluxed until TLC showed no starting
material (approximately 4–8 h). The reaction mixture was slowly
cooled to 5 ꢀC and stirred at this temperature for additional 12 h.
The resulting yellow precipitate was filtered, immediately washed
with Et2O (3 ꢃ 5 mL) and then dried in vacuo.
1,10-biiso quinoline)dichloridoplatinum(II) (15). 1H NMR (400 MHz,
[D]6DMSO)
d
7.02–7.75 (2H, 2 ꢃ NH), 5.44–6.95 (4H, m, H-5,50,8,80),
4.75 4.38 (2H, br, H-1,10), 3.78 3.75 3.74 3.72 3.70 (12H, 4 ꢃ OMe),
3.05–3.20 (2H, m, H-3e,30e), 2.63–2.93 (2H, m, H-3a, 30a), 2.51–2.54
(2H, m, H-4e, 40e), 2.09–2.33 (2H, m, H-4a, 40a), 1.03 (t, CH3CH2OH),
Anal. Calcd for C22H28N2O4PtCl2,C2H5OH: C, 41.39; H, 4.92; N, 4.02.
Found: C, 41.08; H, 4.84; N, 4.09.
6.6.1.1. Rac-6,60,7,70-Tetrahydroxy-1,10,2,20,3,30,4,40-octahydro-1,10-
6.7.1.5. (1R, 1R0)-6,60,7,70-tetramethoxy -1,10,2,203,30,4,040-octahydro-
biisoquinoline Dihydrobromides (10). Yellow powders, m.p. 228–
1,10-biiso quinoline)dichloridoplatinum(II) (16). 1H NMR (400 MHz,
230 ꢀC, 1H NMR (400 MHz, D2O)
d
6.63–6.85 (2H, m, H-8,80) 5.68–
[D]6DMSO)
d
7.04–7.75 (2H, 2 ꢃ NH), 5.44–6.97 (4H, m, H-5,50,8,80),
6.526 (2H, m, H-5,50), 5.01–5.20 (2H, m, H-1,10), 3.4–.81 (6H, m,
H-3e, H-30e, H-3a, H-3a0, 2 ꢃ NH), 2.92–3.39 (4H, m, H-4e, H-4e0,
H-4a, H-4a0), Anal. Calcd for C18H22N2O4Br2: C, 44.10; H, 4.52; N,
5.71. Found: C, 43.89; H, 4.46; N, 5.84.
4.75 4.39 (2H, br, H-1,10), 3.79 3.75 3.74 3.72 3.70 (12H, 4 ꢃ OMe),
3.06–3.20 (2H, m, H-3e,30e), 2.62–2.93 (2H, m, H-3a, 30a), 2.50–2.54
(2H, m, H-4e, 40e), 2.06–2.33 (2H, m, H-4a, 40a), 1.03 (t, CH3CH2OH),
Anal. Calcd for C22H28N2O4PtCl2,C2H5OH: C, 41.39; H, 4.92; N, 4.02.
Found: C, 41.11; H, 4.79; N, 4.05.
6.6.1.2. Meso-6,60,7,70-Tetrahydroxy-1,10,2,20,3,30,4,40-octahydro-1,10-
biisoquino line Dihydrobromides (11). Yellow powders, m.p. 236–
6.8. 6,60,7,70-tetrahydroxy-1,10,2,20 3,30, 4,40-octahydro-1,10-
biisoquinoline)dichloridoplatinums(II)
238 ꢀC, 1H NMR (400 MHz, D2O)
d
6.72–6.87 (2H, m, H-8,80) 6.21–
6.51 (2H, m, H-5,50), 5.20–5.43 (2H, m, H-1,10), 3.38–3.80 (6H, m,
H-3e, H-30e, H-3a, H-3a0, 2 ꢃ NH), 2.86–2.97 (4H, m, H-4e, H-4e0, H-
6.8.1. General procedure F2
4a, H-4a0); 13C NMR (100 MHz, D2O)
d
145.5 144.7 144.4 144.1 (C-
The BIIQs were dissolved at 60–65 ꢀC in water (50 mL). After
addition of the equimolar amount of K2PtCl4, the mixture was
neutralized slowly with 0.1 M NaOH to pH 6. The complexes
precipitated out, were washed with H2O and with EtOH and were
dried.
6,60,7,70), 126.8 (4a,4a0), 125.9 (C-8a,8a0), 117.7 116.8 116.7 116.3
(C-5,50), 113.5 113.3 112.1109.3 (C-8,80), 57.8 57.7 57.5 55.9 55.8 55.5
(C-1,10), 41.8 41.6 (C-3,30), 25.5 24.3 24.1 (C-4,40), Anal. Calcd for
C18H22N2O4Br2: C, 44.10; H, 4.52; N, 5.71. Found: C, 44.36 H, 4.69; N,
5.58.
6.8.1.1. (Rac-6,60,7,70-tetrahydroxy-1,10, 2,203,30,4,40-octahydro-1,10-
biisoquinoline)dichloridoplatinum(II) (17). IR (cmꢁ1 neat) 3150–
3600 (S, -OH) 2250–2700 (-NHþ-) 1250 (S, Ar-O); 1H NMR
6.7. (6,60,7,70-tetramethoxy -1,10-biiso
quinoline)dichloridoplatinums (II)
(400 MHz, [D]6DMSO)
d 8.60–9.20 (4H, m, OH), 7.01–7.75 (2H, m,
6.7.1. General procedure F1
2 ꢃ NH), 5.45–6.95 (4H, m, H-5,50,8,80), 4.51 4.15 (2H, m, H-1,10),
3.13–3.89 (4H, m, H-3), 2.63–2.98 (4H, m, H- 4), 1.03 (t, CH3CH2OH),
Anal. Calcd for C18H20N2O4PtCl2,C2H5OH: C, 37.39; H, 4.39; N, 4.36.
Found: C, 37.01; H, 4.54; N, 4.23.
The BIIQs were dissolved at 60–65 ꢀC in 0.05 M HCl (50 mL).
After addition of the equimolar amount of K2PtCl4, the mixture was
neutralized slowly with 0.1 M NaOH to pH 6. The complexes
precipitated out, were washed with H2O and with EtOH and were
dried.
6.8.1.2. (Meso-6,60,7,70-tetrahydroxy-1, 10,2,203,30,4,40-octahydro-1,10-
biisoquinoline)dichloridoplatinum(II) (18). IR (cmꢁ1 neat) 3300–
3600 (S, -OH) 2250–2700 (-NHþ-) 1250 (S, Ar-O); 1H NMR
6.7.1.1. (6,60,7,70-tetramethoxy-3,30,4,40-tetrahydro-1,10-biisoquinoli-
ne)dichlorido platinum(II) (12). H1 NMR (400 MHz, [D]6DMSO)
(400 MHz, [D]6DMSO)
d
7.80–9.20 (4H, OH), 7.05–7.20 (2H, 2 ꢃ NH),
d
6.00–8.42 (4H, m, H-5,50,8,80), 3.89 3.88 3.85 3.84 3.82 3.80 3.77
5.50–6.80 (4H, m, H-5,50,8,80), 4.40–4.60 (2H, m, H-1,10), 3.13–3.89
(4H, m, H-3), 2.01–2.90 (4H, m, H- 4), 1.03 (t, CH3CH2OH), Anal.
Calcd for C18H20N2O4PtCl2,C2H5OH: C, 37.39; H, 4.39; N, 4.36.
Found: C, 37.54; H, 4.51; N, 4.26.
3.74 3.72 3.71 3.70 3.69 3.68 3.67 3.58 3.56 (12H, 4 ꢃ OMe), 2.65–
3.13 (4H, m, H-3,30), 2.05–2.54 (4H, m, H-4,40), Anal. Calcd for
C22H24N2O4PtCl2,2H2O: C, 38.72; H, 4.14; N, 4.10. Found: C, 38.41;
H, 4.02; N, 3.94.
6.9. Cytotoxicity assay (rapid colorimetric assay) [24,25]
6.7.1.2. (Rac-6,60,7,70-tetramethoxy-1,10, 2,203,30,4,40-octahydro-1,10-
biisoquinoline)dichloridoplatinum(II) (13). 1H NMR (400 MHz,
The assay using MTT [3-(4,5–di methylthiazole-2-yl)-2,5-
diphenyltetrazolium bromide] against Hepa59T/VGH (human liver
carcinoma), WiDr (Human colon adenocarcinoma), Hela (human
cervical epitheloid carcinoma) and MCF-7 (Human breast adeno-
carcinoma) tumor cells was based on the reported methods. The
tumor cells were purchased from the American Type Culture
Collection (ATCC). The tumor cell lines and culture conditions used
were the same as previously described. Briefly, cells seeded at
a density 5 ꢃ10ꢁ3 cells per well (0.1 mL) were incubated for 24 h
and 2-fold dilutions (0.1 mL) of tested samples were added. At the
end of 72 h incubation, the medium was replaced with a fresh
medium without fetal calf serum. The cells were then labeled with
[D]6DMSO)
d
7.01–7.75 (2H, 2 ꢃ NH), 5.45–6.95 (4H, m, H-5,50,8,80),
4.76 4.37 (2H, 2s, H-1,10), 3.78 3.75 3.74 3.71 3.70 (12H, 4 ꢃ OMe),
3.03–3.19 (2H, m, H-3e,30e), 2.64–2.93 (2H, m, H-3a, 30a), 2.50–2.54
(2H, m, H-4e, 40e), 2.08–2.33 (2H, m, H-4a, 40a), 1.03 (t, CH3CH2OH),
Anal. Calcd for C22H28N2O4PtCl2,C2H5OH: C, 41.39; H, 4.92; N, 4.02.
Found: C, 40.07; H, 4.74; N, 4.03.
6.7.1.3. (Meso-6,60,7,70-tetramethoxy-1,10,2,203,30,4,40-octahydro-1,10-
biiso quinoline)dichloridoplatinum(II) (14). 1H NMR (400 MHz,
[D]6DMSO)
d
6.95–8.15 (2H, 2 ꢃ NH), 5.55–6.95 (4H, m, H-5,50,8,80),
4.88 4.76 4.55 4.43 (2H, 4s, H-1,10), 3.79 3.77 3.75 3.73 (6H, 2OMe),
3.71 (6H, 2OMe), 3.01–3.13 (2H, m, H-3e,30e), 2.66–2.99 (2H, m,
H-3a, 30a), 2.08–2.54 (3H, m, H-4,40),1.03 (t, CH3CH2OH), Anal. Calcd
10
mL of MTTstock solution (5 mg/mL) and the incubation continued
at 37 ꢀC for 2 h. The medium was removed and 0.2 mL of DMSO was

62
C.-Y. Kuo et al. / European Journal of Medicinal Chemistry 45 (2010) 55–62
[6] K. Orito, M. Miyazawa, R. Kanbayashi, M. Tokuda, H. Suginome, J. Org. Chem.
64 (1999) 6583–6596.
[7] P.S. Charifson, J.P. Bowen, S.D. Wyrick, A.J. Hoffman, M. Cory, A.T. McPhail,
R.B. Mailman, J. Med. Chem. 32 (1989) 2050–2058.
[8] D. Beaumont, R.D. Waigh, M. Sunbhanich, M.W. Nott, J. Med. Chem. 29 (1983)
507–515.
[9] A.H. Nielsen, J. Org. Chem. 35 (1970) 2498–2503.
addes to each well to dissolve formazan crystals. Cytotoxic dose of
50% growth inhibition (The IC50 was defined bycomparisonwith the
untreated cells as the concentration of test sample resulting in 50%
reduction of absorbance) was then estimated from optical density
data at 550 nm. Negative control was also included and the tests
were done quadruplicate and repeated at least twice.
[10] M. Kato, K. Sasano, C. Kosuge, M. Yamazaki, S. Yano, M. Kimura, Inorg. Chem.
35 (1996) 116–123.
[11] J.C. Plaquevent, T. Perrard, C. Cahard, Chemistry 8 (2002) 3300–3307.
[12] D. Lucet, L. Toupet, G.T. Le, C. Mioskowski, J. Org. Chem. 62 (1997) 2682–2683.
[13] E.R. Jamieson, S.L. Lippard, Chem. Rev. 99 (1999) 2467–2498.
[14] H. Ott, G.E. Hardtmann, M.D. Albert, A.J. Frey, J.H. Gogerty, G.H. Leslie,
J.H. Trapold, Journal of Medicinal Chemistry (1968) 777–787.
[15] W.J. Gensler, in: R. Adams (Ed.), Organic Reactions, vol. 6, Wiley, New York,
1951, pp. 191–206.
Acknowledgements
We would like to thank Dr. Sun, researcher of the National
Research Institute of Chinese Medicine, for helpful cytotoxicity
assay.
[16] Z.M.A. Judeh, C.B. Ching, J. Bu, A. McCluskey, Tetrahedron. Lett. 29 (2002)
5089–5091.
[17] S.O. Ano, F.P. Intini, G. Natile, L.G. Marzilli, Inorg. Chem. 38 (1999) 2989–2999.
[18] M.J. Abrams, B.A. Murrer, Science 261 (1993) 725–731.
[19] M.A. Fuertes, C. Alonso, J.M. Perez, Chem. Rev. 103 (2003) 645–662.
[20] C.Y. Kuo, M.J. Wu, Y.H. Kuo, Eur. J. Med. Chem. 41 (2006) 940–949.
[21] D.J. Cram, F.A.A. Elhafez, J. Am. Chem. Soc. 74 (1952) 5828–5835.
[22] M.C. Elliott, E. Williams, Org. Biomol. Chem. 1 (2003) 3038–3047.
[23] P. D’Ocon, R. Blasco, L. Candenas, D. Ivorra, S. Lopez, C. Villaverde, L. Castedo,
D. Cortes, Eur. J. Pharmacol. 196 (1991) 183–187.
References
[1] E.J. Shin, M.R. Hajaligol, F. Rasouli, Fuel 83 (2004) 1445–1453.
[2] A.R. Carroll, R.A. Davis, P.I. Forster, G.P. Guymer, R.J. Quinn, J. Nat. Prod. 64
(2001) 1572–1573.
[3] M.A. Rashid, K.R. Gustafson, M.R. Boyd, J. Nat. Prod. 64 (2001) 1249–1250.
[4] N. Sotomayeor, E. Dominguez, E. Lete, J. Org. Chem. 61 (1996) 4062–4072.
[5] S.A. Kim, Y. Kwon, J.H. Kim, M.T. Muller, I.K. Chung, Biochemistry 37 (1998)
16316–16324.
[24] C.M. Sun, W.J. Syu, Y.T. Huang, C.C. Chen, J.C. Ou, J. Nat. Prod. 60 (1997) 382–384.
[25] T.J. Mosmann, J. Immunol. Meth. 65 (1983) 55–63.