Synthesis and cytotoxicity evaluation of novel indolylpyrimidines and indolylpyrazines as potential antitumor agents

Article abstract of DOI:10.1016/S0968-0896(00)00337-0

Novel indolylpyrimidines and indolylpyrazines have been synthesized as potential antitumor agents. They were screened in a panel of 60 human tumor cell lines in vitro. Compounds 7, 9, 10, 15, 21 exhibited efficiently cytotoxic activities with GI₅₀ values in the low micromolar range against a variety of human cancer cell lines. 2,4-Bis(3′-indolyl)pyrimidine 8 displayed selective cytotoxic activity against IGROV1 tumor cell line with the GI₅₀ value below 0.01 μM.

Full text of DOI:10.1016/S0968-0896(00)00337-0

Bioorganic & Medicinal Chemistry 9 (2001) 1149±1154
Synthesis and Cytotoxicity Evaluation of Novel Indolylpyrimidines
and Indolylpyrazines as Potential Antitumor Agents
Biao Jiang,* Cai-Guang Yang, Wen-Nan Xiong and Jun Wang
Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, P.R.China
Received 26 September 2000;accepted 2 December 2000
AbstractÐNovel indolylpyrimidines and indolylpyrazines have been synthesized as potential antitumor agents. They were screened
in a panel of 60 human tumor cell lines in vitro. Compounds 7, 9, 10, 15, 21 exhibited eciently cytotoxic activities with GI50 values
0
in the low micromolar range against a variety of human cancer cell lines. 2,4-Bis(3 -indolyl)pyrimidine 8 displayed selective cyto-
toxic activity against IGROV1 tumor cell line with the GI50 value below 0.01 mM. # 2001 Elsevier Science Ltd. All rights reserved.
Chemistry
Introduction
Natural bisindole alkaloids have emerged as an impor-
tant structural class based upon their high degree of
Meridianin D, isolated from the marine tunicate Apli-
dium meridianum, showed cytotoxicity toward LMM3
(murine mamarian adenocarcinoma cell line) with an
1
biological activity. A very interesting group of this
class of compounds incorporates a ®ve- or six-mem-
8
IC50 value of 33.9 mM. It has a structure of brominated
2À5
bered heterocyclic ring between the two indole rings.
indole ring linking a 2-aminopyrimidine at the 3-position
of indole. We have reported an ecient synthesis of meridi-
anin D (1) and its analogue 6-debromomeridianin D (2),
Due to the interesting biological activities and unique
chemical structures of marine indole alkaloids and its low
availability, marine indole alkaloids as lead compounds
for discovery of new drugs have been an attractive ®eld in
medicinal chemistry. In our e€orts to search for novel
antitumor agents, we have designed and synthesized a
novel type of bisindole alkaloids, including the analogues
of the cytotoxic marine bisindole alkaloid, nortopsen-
tines in which imidazole moiety was replaced with a
thiazole, pyrazinone or pyrazine ring. Those bisindole
analogues were found to possess signi®cant cytotoxic
activities against human cancer cell lines with GI
9
via the palladium catalyzed cross-coupling reaction.
Moreover, a series of novel bis(N-tosylindolyl)pyrim-
idine alkaloids 5±7 were synthesized by palladium cata-
lyzed reaction of 2,4-dichloropyrimidines with N-tosyl-
9
,10
3-indolylboronic acid.
Deprotection of the N-toluene-
sulfonyl group in the indole ring with sodium hydroxide
in re¯uxing methanol a€orded the corresponding 2,4-
0
bis(3 -indolyl)pyrimidines 8±10 (Scheme 1).
In order to further study the SAR of bisindole alka-
loids, we planned to synthesize the indole alkaloids
bearing a pyrazine ring. In the previous paper, we have
5
0
6
,7
values in the low micro-molar concentration range.
These results prompted us to further study the SAR of
new type of indole alkaloids.
reported the synthesis of 2,5-bisindolylpyrazine from 3-
7
(
a-azidoacetyl)indole via condensation reaction. How-
In this paper, we designed and synthesized new series
of 4-indolylpyrimidines, 2,4-bis(3 -indolyl)pyrimidines,
5
which were evaluated for cytotoxic activity against the
diverse human tumor cell lines in vitro by the National
Cancer Institute, USA.
ever, this method was not suitable to the synthesis of
bisindolylpyrazines bearing a functional group in pyra-
zine ring. Therefore, a new synthetic route starting from
2-aminopyrazine (11) via the Suzuki cross-coupling
reaction was employed, as depicted in Scheme 2. Thus 2-
aminopyrazine (11) was converted to 2-amino-3,5-
diboromopyrazine (12) by bromination with N-bromo-
succinimide in aqueous dimethyl sulfoxide in 85%
yield. Treatment of the dibromopyrazine 12 with
sodium methoxide regioselectively a€orded 2-amino-3-
methoxyl-5-bromopyrazine (14) in methanol under
0
-indolylpyrazines, and 3,5-bis(3 -indolyl)pyrazines,
0
*
6
Corresponding author. Tel.: +86-21-6416-3300;fax: +86-21-6416-
128;e-mail: jiangb@pub.sioc.ac.cn
0968-0896/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved.
PII: S0968-0896(00)00337-0

1150
B.Jiang et al./ Bioorg.Med.Chem.9 (2001) 1149±1154
Scheme 1.
Scheme 2.
1
1
re¯uxing. 2-(N,N-Dimethyl)amino-3,5-dibromopyr-
azine (13) was obtained by treatment 12 with sodium
hydride and iodomethane in dimethylformamide quan-
titatively.
(triphenylphosphine)palladium and aqueous cesium
carbonate in DME under re¯uxing. The structure of
compound 15 was con®rmed by X-ray single crystal
analysis (Fig. 1). The mild condition and good yields of
the cross-coupling reaction between the 3-indolylboronic
acid and the brominated pyrazines are considered to be
an excellent method for the preparation of indolylpyr-
azines. Bisindo-lylpyrazine 20 was obtained through
cross-coupling reaction between 2-(N,N-dimethyl)-
amino-3,5-dibromopyrazine 13 and N-tosyl-3-indo-
Finally, the desired monoindolylpyrazine 15 or bisindo-
lylpyrazine 17 were respectively prepared by Suzuki
cross-coupling reaction between 2-amino-3,5-dibromo-
pyrazine 12 and 1.1 equiv or 2.2 molar equiv of N-tosyl-
3
-indolylboronic acid 3 in the presence of 10% tetrakis-

B.Jiang et al./ Bioorg.Med.Chem.9 (2001) 1149±1154
1151
SR, CNS Cancer SF-539, and breast cancer MDA-MB-435
cell lines with the GI50 value of 0.22, 0.16, and 0.22 mM,
respectively. 2,4-Bis(3-indolyl)pyrimidine 8 displayed
strong selective cytotoxic activity against IGROV1 tumor
cell line with GI50 values below 0.01 mM.
One dose primary anticancer assay results indicated that
N-protected bis(indolyl)pyrazines 17, 20 were inactive
against NCI-H460, MCF7 and SF-268 tumor cells. 3,5-
0
Bis(3 -indolyl)pyrazine 21 demonstrated good inhibitory
e€ects against a variety of tumor cell lines with the GI50
values less than 10 mM. However, compared to 2,5-
0
7
bis(3 -indolyl)pyrazine and its N-methylated derivative,
their antitumor activity were weaker. To our surprise,
-amino-5-bromo-3-(N-tosyl)pyrazine 15 also showed
2
good inhibitory activity against a variety of tumor cell
lines with GI50 value below 10 mM. It was noted that
0
excellent selective inhibition against CCRF-CEM cancer
2-amino-3-methoxyl-5-(3 -indolyl)pyrazine 19 exhibited
lines (GI =0.81 mM) and HOP-92 cancer lines
5
0
(
GI =0.03 mM).
5
0
In summary, we have synthesized a series of novel
indolylpyrimidines and indolylpyrazines that showed
sucient inhibitory e€ects in the growth of a wide variety
of human tumor cell lines in vitro. 2-Amino-3-meth-
Figure 1. ORTEP drawing of the X-ray crystal structure of compound
Ê
5. Crystal structure data: cell parameters: a=15.843(4) A, b=
0
oxyl-5-(3 -indolyl)pyrazine 19 exhibited good selective
inhibition against CCRF-CEM and HOP-92 cancer lines
1
Ê
Ê
ꢀ
Ê
3
8
.936(5) A, c=17.966(7) A, g=104.68(2) , V=2460(1) A. Space
/a (#14). Z value 4. No. of observations: 2542. No. of vari-
ables: 299. Residuals: R;Rw 0.048;0.053. Goodness of ®t indicator
.84.
0
group: P2
1
and 2,4-bis(3 -indolyl)pyrimidine 8 displayed excellent
selective inhibitory activity against the IGROV1 tumor
cell line. They are considered to be promising lead
compounds for the further development of indole alka-
loids as antitumor agents.
1
lylboronic acid 3 in 79% yield and 2-amino-3-methoxyl-
0
5
-(N-tosyl-3 -indolyl)-pyrazine 18 was gained by cou-
pling of 2-amino-3-methoxyl-5-bromopyrazine 14 and 3
in 91% yield under the same condition. Deprotection of
the N-toluenesulfonyl group with sodium hydroxide in
re¯uxing methanol a€orded the corresponding mono-
indolyl- and bisindolyl-pyrazines 16, 19 and 21 in high
yields.
Experimental
All melting points were measured with a WRS-1A digi-
tal melting point apparatus, without correction. IR
spectra were determined with a Shimadzu IR-440 spectro-
1
13
meter. H NMR and C NMR spectra were recorded
on a Bruker AM-300 instrument. The chemical photo
shifts are expressed in ppm and coupling constants are
given in Hz. Low-resolution MS spectra were obtained
on a VG-Quattro or HP-5969A spectrometer and high-
resolution MS spectra were recorded on a Finnigan
MAT-95 spectrometer. Elemental analyses were carried
out on a Heraeus Rapid-CHNO instrument. Column
chromatography was performed on silica gel H (10±40
mm). Reagents purchased commercially from Aldrich
were used without further puri®cation. Solvents were dried
Pharmacological Results and Discussion
The obtained indole alkaloids were evaluated for cyto-
toxicity in the National Cancer Institute (USA) in vitro
disease-oriented antitumor screening using sulforhod-
amines B (SRB) assay including a panel of 60 human
tumor cell lines representing nine di€erent cancer
1
2À14
types.
The results are presented in Table 1 as GI50
values in mM.
0
using standard procedures. 2,4-Bis(N-tosyl-3 -indolyl)pyr-
imidines (5), (6) and (7) were prepared according our pre-
The natural product, meridianin D 1 showed weak
antitumor activities against a variety of tumor cell lines,
and its analogue 6-debromomeridianin D 2 did not
show any antitumor activity at all.
9
vious reported.
0
General procedure for synthesis of 2,4-bis(3 -indolyl)pyr-
0
9
imidines. 2,4-Bis(N-tosyl-3 -indolyl)pyrimidines and
sodium hydroxide in methanol were re¯uxed for 2 h.
After cooled to rt, methanol was removed under
vacuum and the residue was dispersed into water and
ethyl acetate. The organic layer was separated and
washed with water and brine successively. Then the
organic phase was dried over anhydrous sodium sulfate
0
Although 2,4-bis(N-tosyl-3 -indolyl)pyrimidines 5±6
were inactive, their N-detosylated derivatives 8±9
demonstrated good inhibitory e€ects against a variety
of tumor cell lines with the GI50 values less than 10 mM.
Among these compounds, bis(N-tosylindolyl)pyrimidine 7
exhibited signi®cant inhibitory activities against leukemia

1152
B.Jiang et al./ Bioorg.Med.Chem.9 (2001) 1149±1154
Table 1. Cancer cell growth inhibitory activity of compounds 1, 7±10 and 15, 19, 21 in vitroa,b
Panel/cell lines
1
7
8
910
15
1 92 1
Leukemia
CCRF-CEM
RPMI-8226
SR
41.1
22.6
17.3
NDc
0.37
0.22
1.51
1.91
4.24
1.52
3.90
11.3
1.13
2.80
9.53
ND
2.28
0.77
0.81
1.01
15.0
ND
2.74
3.24
Non-small cell lung cancer
A549/ATCC
HOP-92
15.7
45.6
30.0
0.52
1.42
0.39
3.28
1.70
2.87
3.64
2.03
2.65
3.26
2.34
3.08
1.81
0.87
2.82
31.2
0.03
26.3
3.33
3.20
2.12
NCI-H460
Colon cancer
COLO 205
HCT-116
KM12
18.7
18.6
24.2
0.36
0.40
0.51
5.44
4.36
3.93
4.58
4.56
3.79
8.32
3.43
4.18
2.61
0.31
2.34
29.0
21.7
9.19
2.30
3.13
2.19
CNS cancer
SF-295
SF-539
SNB-19
U251
35.3
32.6
20.7
30.9
0.50
0.16
0.56
0.36
2.93
4.37
4.81
3.86
3.29
11.7
7.88
6.46
3.14
7.14
5.26
4.19
2.86
2.87
0.73
0.91
29.4
33.7
66.5
31.0
2.33
4.21
1.15
3.37
Melanoma
LOX IMVI
M14
25.3
24.6
0.48
0.36
2.82
1.99
3.62
4.32
4.84
4.08
2.66
1.76
25.3
30.1
2.51
1.89
Ovarian cancer
IGROV1
OVCAR-5
23.7
17.5
0.25
0.38
<0.01
>100
1.14
5.50
1.86
8.13
1.37
4.15
19.6
39.6
3.24
4.68
Renal cancer
SN12C
UO-31
21.7
18.7
0.53
0.58
2.78
3.98
1.68
6.97
ND
5.53
0.42
4.36
5.88
21.2
2.88
3.73
Prostate cancer
PC-3
30.1
0.39
2.72
3.49
2.84
2.23
26.5
3.69
Breast cancer
MCF7
MDA-MB-435
19.9
26.6
0.39
0.22
2.74
4.52
3.05
5.87
3.55
5.76
0.82
0.29
2.85
23.5
2.30
3.31
a
Data obtained from NCI's in vitro disease-oriented tumor cells screen.
GI50 is the molar concentration causing 50% growth inhibition of tumor cells. Compounds with GI50>100 mM are considered inactive. GI50 values
b
in mM.
Not determined.
c
overnight. After evaporation under vacuum, the solid
residue was puri®ed by chromatography to give 2,4-
bis(3 -indolyl)pyrimidines.
calcd for C H N : 324.1375. Found: 324.1357.
21 16 4
0
0
5-Methoxy-2,4-bis(3 -indolyl)pyrimidine
9
(10).
Yield
ꢀ
1532, 1453, 1432, 1297, 1242, 1130, 1035 cm
2%. Mp 291.4±292.8 C;IR (KBr) nmax 3384, 1566,
0
À1
1
2
>
1
7
,4-Bis(3 -indolyl)pyrimidine (8). Yield 97%. Mp
;
H
ꢀ
300 C;IR (KBr) n
439, 1265, 1171, 1092 cm ; H NMR (DMSO-d ) d
.16±7.27 (m, 4H), 7.50±7.55 (m, 2H), 7.59 (d, J=5.4
3391, 1615, 1578, 1548, 1455,
À1
NMR (DMSO-d ) d 4.09 (s, 3H), 7.14±7.28 (m, 4H),
max
6
1
7.49±7.56 (m, 2H), 8.19 (d, J=1.5 Hz, 1H), 8.40 (d,
J=1.8 Hz, 1H), 8.54 (s, 1H), 8.61 (d, J=7.7 Hz, 1H),
8.89- 8.92 (m, 1H), 11.52 (br s, 1H), 11.80 (br s, 1H);
6
1
3
Hz, 1H), 8.33 (d, J=1.1 Hz, 1H), 8.41 (d, J=1.8 Hz,
C
1
1
H), 8.62±8.67 (m, 3H), 11.64 (br s, 1H), 11.83 (br s,
+
NMR (DMSO-d ) d 56.1, 110.2, 111.8, 115.6, 119.9,
6
H);EIMS m/z (%) 310 (M , 100), 141 (22). Anal.
120.5, 121.6, 121.8, 122.2, 122.7, 125.6, 126.2, 127.2,
131.5, 131.7, 136.2, 137.0, 138.8, 146.5, 150.8, 156.2;
calcd for C H N : C, 77.40;H, 4.55;N, 18.05. Found:
2
C, 77.30;H, 4.47;N, 17.98.
0
14
4
+
EIMS m/z (%) 340 (M , 100), 297 (21), 183 (50), 155
(55), 128 (41), 101 (16);HRMS calcd for C 21H N O:
340.1324. Found: 340.1322.
16 4
0
Mp 263.2±265.3 C;IR (KBr)
5
-Methyl-2,4-bis(3 -indolyl)pyrimidine (9). Yield 97%.
ꢀ
n
max
À1
3397, 1618, 1552,
1
1
538, 1445, 1239, 1114, 1010 cm ; H NMR (DMSO-
2-Amino-3,5-dibromopyrazine (12). N-Bromosuccinimide
(14.95 g, 84 mmol) is added over 50 min to a mixture of
d6) d 2.51 (s, 3H), 7.09±7.28 (m, 4H), 7.86 (dd, J=13.4
and 7.3 Hz, 2H), 8.07 (d, J=2.1 Hz, 1H), 8.24 (d, J=1.5
Hz, 1H), 8.59 (s, 1H), 7.86 (dd, J=14.0 and 7.9 Hz,
2-aminopyrazine (11) (3.80 g, 40 mmol) in DMSO (80
ꢀ
mL) and H O (2 mL) below 15 C. After stirring for 6 h
2
2
H), 11.61 (br s, 1H), 11.80 (br s, 1H); 13C NMR
at rt, the mixture is poured into ice-water (250 mL) and
extracted with EtOAc (4Â50 mL). The extract is ®ltered,
washed with 5% aq Na CO (50 mL) and H O, and
(
DMSO-d ) d 18.4, 112.3 113.7, 116.0, 120.5, 120.8,
6
1
1
22.3, 122.6, 122.7, 126.2, 127.0, 128.5, 128.7, 129.6,
29.8, 136.6, 136.8, 137.6, 158.4, 160.6, 161.7;EIMS m/z
2
3
2
dried with anhydrous sodium sulfate. The solvent is
evaporated and the residue is sublimed to recrystallize
+
(
%) 324 (M , 100), 181 (7), 154 (21), 115 (12);HRMS

B.Jiang et al./ Bioorg.Med.Chem.9 (2001) 1149±1154
1153
from EtOH to give 2-amino-3,5-dibromopyrazine (12)
8
8.12 (d, J=8.0 Hz, 1H), 8.26 (d, J=6.5 Hz, 1H), 8.35
13
ꢀ
3451, 3284, 1625, 1508,
.61 g (85% yield) as white solid. Mp 117.6±118.8 C
ꢀ
(d, J=2.7 Hz, 2H), 8.65 (s, 1H); C NMR (DMSO-d6)
1
5
(
lit. mp 116 C);IR (KBr) n
453, 1316, 1099 cm ; H NMR (CDCl ) d 5.00 (br s,
d 20.9, 21.0, 113.0, 113.2, 117.9, 119.9, 122.3, 122.4, 123.3,
123.5, 123.7, 125.1, 125.2, 125.9, 126.8, 127.2, 128.2, 129.2,
130.3, 131.9, 133.9, 134.0, 134.1, 134.8, 136.0, 138.7,
max
À1
1
1
2
2
3
+
H), 7.97 (s, 1H);EIMS m/z (%) 253 (M , 100),
51:255 (52:53), 172:174 (24:23), 66 (20).
+
145.6, 145.7, 152.1;EIMS m/z (%) 634 (M , 14),
478 (44), 323 (42), 262 (100), 183 (87), 108 (52);
HRMS calcd for C H N O S : 633.1504. Found:
633.1505.
2
-(N,N-Dimethyl)amino-3,5-dibromopyrazine (13). To a
3
4
27
5
4 2
solution of 2-amino-3,5-dibromopyrazine (12) (253 mg,
mmol) in DMF is added 60% NaH (88 mg, 2.2
1
0
mmol). Then, iodomethane (568 mg, 4 mmol) is added
to the mixture in one port. After stirring for 15 min, the
mixture is treated with water (5 mL) and extracted with
ether (2Â10 mL). The organic layer is washed with
water and brine and dried over anhydrous sodium sul-
fate. The solvent is evaporated and the residue is puri®ed
with column chromatography to give a yellow liquid 13
2-Amino-3-methoxyl-5-(N-tosyl-3 -indolyl)pyrazine (18).
ꢀ
3289, 3152, 1629, 1561, 1486, 1372, 1220, 1174, 1092
Yield 89%. Mp 214.3±215.5 C;IR (KBr) nmax 3464,
À1
1
cm ; H NMR (DMSO-d ) d 2.34 (s, 3H), 4.08 (s, 3H),
6
6.12 (br, 2H), 7.27±7.38 (m, 4H), 7.85 (d, J=8.4 Hz,
2H), 7.97±8.06 (m, 3H), 8.23 (dd, J=7.06 and 1.0 Hz,
+
1H);EIMS m/z (%) 394 (M , 33), 239 (100), 212 (8),
155 (6);HRMS calcd for C H N O S: 394.1100.
(
248 mg, 90%). IR (KBr) n
2954, 1543, 1498, 1403,
max
20 18
4
3
À1
1
1
160, 1046 cm ; H NMR (CDCl ) d 3.09 (s, 6H), 8.10
Found: 394.1108. Anal. calcd for C H N O S: C,
20 18 4 3
60.91;H, 4.57;N, 14.21. Found: C, 60.81;H, 4.72;N,
14.09.
3
+
(
4
s, 1H);EIMS m/z (%) 281 (M , 26), 266 (12), 252 (45),
4 (100).
0
2
2
-Amino-3-methoxyl-5-bromopyrazine (14). A mixture of
-amino-3,5-dibromopyrazine (12) (5.06 g, 20 mmol)
2-(N,N-Dimethyl)amino-3,5-bis(N-tosyl-3 -indolyl)pyrazine
ꢀ
2924, 1597, 1548, 1493, 1446, 1373, 1270, 1172, 1089
(20). Yield 94%. Mp 120.9±121.7 C;IR (KBr) nmax
and sodium methoxide (1.06 g, 20 mmol) in methanol is
re¯uxed. After the reaction was completed, the mixture
is cooled to rt slowly and the product is precipitated as a
colorless crystal weighed 3.43 g, 84% yield. Mp 140.5±
À1
1
cm ; H NMR (CDCl ) d 2.31 (s, 3H), 2.33 (s, 3H),
2.86 (s, 6H), 7.20±7.42 (m, 8H), 7.79±7.87 (m, 4H), 8.02
(s, 1H), 8.02±8.10 (m, 2H), 8.16±8.23 (m, 2H), 8.19 (s,
3
o
11
o
13
1
41.6 C (lit. mp 138 C);IR (KBr) n
3489, 3287,
À1
1H), 8.46 (s, 1H); C NMR (CDCl ) d 21.5, 40.9, 113.5,
max
3
1
3
140, 1633, 1544, 1505, 1423, 1304, 1222, 1007 cm ; H
113.6, 120.2, 120.9, 122.1, 122.6, 123.5, 123.6, 123.7,
124.9, 125.1, 126.0, 126.9, 128.6, 129.0, 129.8, 129.9,
135.1, 135.6, 136.1, 136.5, 138.6, 145.1, 145.2, 154.9;
EIMS m/z (%) 662 (M , 48), 506 (100), 350 (63), 91
(32);HRMS calcd for C 36H N O S : 661.1834. Found:
661.1826.
NMR (CDCl ) d 5.00 (br s, 2H), 7.97 (s, 1H);EIMS m/z
3
+
(
(
%) 204 (M , 2), 203/205 (5/5), 182 (55), 125 (100), 109
54), 69 (64).
+
31 5 4 2
General procedure for palladium catalyzed cross-coupling
reaction of bromopyrazine with N-tosyl-3-indolylboronic
acid (3). A mixture of N-tosyl-3-indolylboronic acid (3)
General procedure for removal N-tosyl to indolyl-pyra-
zine. The procedure is same as the synthesis of com-
pounds 8±10.
(
1 or 2 mmol), bromopyrazine (1 mmol), DME (15 mL),
aqueous cesium carbonate (1 or 2 mL, 2 M) and tetra-
kis(triphenylphosphine)palladium (0.1 or 0.2 mmol) was
re¯uxed under an argon atmosphere. The reaction was
monitored with TLC. When the reaction completed,
anhydrous sodium sulfate was added. The mixture was
0
2-Amino-3-(3 -indolyl)-5-bromopyrazine
(16).
3469, 3291, 3175,
Yield
ꢀ
1624, 1534, 1514, 1444, 1224, 1130, 987 cm ; H NMR
96%. Mp 187 C (dec.);IR (KBr) n
max
À1
1
®
ltered and the ®ltrate was evaporated under reduced
(DMSO-d ) d 6.34 (br s, 2H), 7.13±7.24 (m, 2H), 7.49 (d,
6
pressure. The residue was subjected to ¯ash column
chromatography (eluted with ethyl acetate/hexane) to
give cross-coupling products.
J=8.0 Hz, 1H), 7.92 (s, 1H), 8.08 (d, J=1.5 Hz, 1H),
1
3
8.22 (d, J=7.7 Hz, 1H), 11.69 (br s, 1H); C NMR
(DMSO-d ) d 110.4, 111.9, 120.3, 121.5, 122.5, 124.1,
6
1
26.1, 126.8, 136.5, 137.8, 138.4, 151.7;EIMS m/z (%)
+
0
2
-Amino-3-(N-tosyl-3 -indolyl)-5-bromopyrazine
(15).
288/290 (M , 100/98), 209 (17), 182 (21), 155 (30), 128
(10);HRMS calcd for C 12H N Br: 288.0009. Found:
288.0002.
ꢀ
297, 3171, 1631, 1448, 1372, 1281, 1172, 1130, 1089,
Yield 90%. Mp 188.9±190.6 C;IR (KBr) nmax 3456,
9
4
3
1
(
1
À1
1
014 cm ; H NMR (DMSO-d ) d 2.32 (s, 3H), 6.69
6
0
br s, 2H), 7.32±7.45 (m, 4H), 7.94±8.09 (m, 4H), 8.11 (s,
+
2-Amino-3-methoxyl-5-(3 -indolyl)pyrazine (19). Yield
3479, 3406, 3140,
max
ꢀ
1733, 1631, 1558, 1491, 1448, 1314, 1216, 1095 cm ; H
H), 8.37 (s, 1H);EIMS m/z (%) 442:444 (M , 52:59),
95%. Mp 182 C (dec.);IR (KBr) n
À1
1
287:289 (97:100), 208 (65), 91 (32). Anal. calcd for
C H N BrO S: C, 51.58;H, 3.39;N, 12.67. Found: C,
NMR (DMSO-d ) d 4.04 (s, 3H), 6.01 (br s, 2H), 7.05±
1
9
15
4
2
6
5
1.54;H, 3.61;N, 12.60.
7.16 (m, 2H), 7.42 (dd, J=7.6 and 1.5 Hz, 1H), 7.83 (d,
J=1.6 Hz, 1H), 8.00 (s, 1H), 8.25 (d, J=7.8 Hz, 1H),
0
13
2
5
1
-Amino-3,5-bis(N-tosyl-3 -indolyl)pyrazine (17). Yield
1%. Mp 246.5 C (dec.);IR (KBr) nmax 3494, 3380,
11.27 (br s, 1H); C NMR (DMSO-d ) d 53.0, 111.6,
6
ꢀ
609, 1478, 1445, 1364, 1279, 1173, 1086 cm
113.2, 119.4, 120.8, 121.3, 122.8, 124.9, 128.8, 134.9,
+
À1
1
;
H
136.7, 143.2, 146.9;EIMS m/z (%) 240 (M , 100), 198
(20), 156 (16);HRMS calcd for C 13H N O: 240.1011.
NMR (DMSO-d /CDCl ) d 2.31 (s, 3H), 2.34 (s, 3H),
6
3
12
4
6
.48 (br, 2H), 7.17±7.42 (m, 8H), 7.90±8.05 (m, 6H),
Found: 240.1028. Anal. calcd for C H N O 1/8H O:
13 12 4 2

1154
B.Jiang et al./ Bioorg.Med.Chem.9 (2001) 1149±1154
C, 64.40;H, 5.06;N, 23.12. Found: C, 64.37;H, 5.14;N,
2
Shyy, S. H.;Wang, J. C.;Liu, L. F. Cell 1988, 53, 433. (f)
Merino, A.;Madden, K. R.;Lane, W. S.;Champoux, J. J.;
Deinberg, D. Nature 1993, 365, 227.
2.93.
0
2. (a) Alvarez, M.;Salas, M. Heterocycles 1991, 32, 1391. (b)
Wipf, P. Chem.Rev. 1995, 95, 2115. (c) Faulkner, D. J. Nat.
Prod.Rep. 1999, 16, 155.
2
-(N,N-Dimethyl)amino-3,5-bis(3 -indolyl)pyrazine (21).
ꢀ
924, 2853, 1723, 1537, 1488, 1455, 1336, 1240, 1170, 1097
Yield 99%. Mp 140.8 C (dec.);IR (KBr) nmax 3396,
2
3
. (a) Wright, A. E.;Pomponi, S. A.;Cross, S. S.;McCarthy,
À1
1
cm ; H NMR (DMSO-d ) d 2.79 (s, 6H), 7.05±7.22 (m,
H), 7.46±7.52 (m, 2H), 8.02 (s, 1H), 8.12 (s, 1H), 8.32±
.37 (m, 2H), 8.48 (s, 1H), 11.46 (br s, 1H), 11.54 (br s,
H); C NMR (DMSO-d ) d 40.9, 111.7, 111.8, 113.3,
13.5, 119.6, 119.7, 121.0, 121.6, 121.7, 121.8, 124.3, 125.1,
25.9, 126.8, 132.7, 136.4, 136.9, 140.3, 142.0, 152.8;
6
P. J.Org.Chem. 1992, 57, 4772. (b) Capon, R. J.;Rooney, F.;
Murray, L. M.;Collins, E.;Sim, A. T. R.;Rostas, J. A. P.;
Butler, M. S.;Carroll, A. R. J.Nat.Prod. 1998, 61, 660.
4. Kohmoto, S.;Kashman, Y.;McConnell, O. J.;Rinehart,
K. L.;Wright, A., Jr.;Koehn, F. J.Org.Chem. 1988, 53,
3116.
4
8
1
1
1
1
3
6
+
5. (a) Sakemi, S.;Sun, H. H. J.Org.Chem. 1991, 56, 4304. (b)
Kawasaki, I.;Yamashita, M.;Ohata, M. Chem.Pharm.Bull.
EIMS m/z (%) 354 (M , 100), 339 (21), 140 (15);HRMS
calcd for C H N : 353.1640. Found: 353.1609.
2
2
19
5
1
996, 44, 1831.
. (a) Gu, X.-H.;Wan, X.-Z.;Jiang, B. Bioorg.Med.Chem.
6
Lett. 1999, 9, 569. (b) Jiang, B.;Gu, X.-H. Heterocycle 2000,
Acknowledgements
53, 1559.
7. Jiang, B.;Gu, X.-H. Bioorg.Med.Chem. 2000, 8, 363.
È
8. Franco, L. H.;Jo€e , E. B. K.;Puricelli, L.;Tatian, M.;
We express deep thanks to Dr. B. L. Robeson, Dr. E. A.
Sausville, Dr. V. L. Narayanan and their colleagues of
National Cancer Institute (USA) for conducting the in
vitro disease-oriented primary antitumor screen. This
work was ®nancially supported by grant from Shanghai
Municipal Committee of Science and Technology.
Seldes, A. M.;Palermo, J. A. J.Nat.Prod. 1998, 61, 1130.
9. Jiang, B.;Yang, C.-G. Heterocycles 2000, 53, 1489.
10. Zheng, Q.;Yang, Y.;Martin, A. R. Heterocycles 1994, 37,
1
1
1
1
761.
1. Camerino, B.;Palamidessi, G. Gazz.Chim.Ital. 1960, 90,
807.
2. Rubinstein, L. V.;Shoemaker, R. H.;Paull, K. D.;Simon,
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