# Synthesis and Anticancer Activity of 1-(1H-Indol-3-yl)-2-(4-diarylmethylpiperazine-1-yl)ethane-1,2-dione Derivatives

Authors: Jun-Rong Jiang; Feng Xu; Han-Gui Wu
Journal: Journal of Chemistry
 (2016)

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## Abstract

Several new 1-(4-diarylmethylpiperazine-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione derivatives were synthesized by acylation of 1-diarylmethylpiperazine with 2-(1H-indol-3-yl)-2-oxoacetyl chloride. Their structures were confirmed by 1H NMR, IR, mass spectra, and elemental analysis. These compounds were further evaluated for their anticancer activity, and most of them were found to have moderate-to-potent antiproliferative activities against Hela, A-549, and ECA-109 cancer cell linesin vitro.


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## Body

## 1. Introduction

Compounds containing the 1-(1H-indol-3-yl)ethane-1,2-dione have antiviral [1], antimicrobial [2], and anticancer [3] activities. For example, compound1, named BMS-378806, has been found to have good HIV-1 attachment inhibitory activity in preventing entry to the host cell by binding to the viral envelope gp120 [1]; compound2, an indolylglyoxamide derivative, has good antibacterial activity against Gram-positive pathogens [2]; compound3 exhibited good ATP-β binding cassette (ABC) transporter modulatory activity and can be used as a potential anticancer agent [3].Until now, the N4-substituent of the piperazine ring of the above-reported compounds contains only an aryl group (Figure 1) [4–6], and there have been few reports on diaryl-substituted compounds. Herein, we adopted a skeleton splicing method to design a new class of compounds, 1-(1H-indol-3-yl)-2-(4-diarylmethylpiperazine-1-yl)ethane-1,2-dione derivatives, which not only contain the skeleton of 1-(piperazine-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione (from compounds1 and2) but also contain the skeleton of a diaryl methyl group (from compound3).Figure 1
Some reported 1-(1H-indol-3-yl)ethane-1,2-dione derivatives.


## 2. Results and Discussion

The reactions for synthesis of 1-(1H-indol-3-yl)-2-(4-diarylmethylpiperazine-1-yl)ethane-1,2-dione derivatives (19–30) are summarised in Scheme 1. Compounds4–6 were prepared from indole and oxalyl chloride in anhydrous ether at 0~5°C under the protection of nitrogen [7]. Compounds7–10 were obtained from diaryl ketones in the presence of sodium borohydride in methanol at reflux [8]. A following chlorination of7–10 with a stoichiometric amount of thionyl chloride in dichloromethane at room temperature afforded11–14 [9]. Compounds11–14 were then treated with piperazine in DMF at 80°C to yield15–18 [9], acylation of which with1 in the presence of triethylamine in dry THF, and then gave compounds19–30 [10].Scheme 1
Synthesis of the compounds (19–30).In the infrared (IR) spectra of19–30, the most characteristic absorptions are at 3154–3225 cm−1 (NH) and 1612–1652 cm−1 ((C=O)2 broad peaks). In the 1H NMR spectra, for compounds19–30, characteristic signals due to the (NH) protons appeared at 12.22–12.46 ppm, and signals due to the (CH) protons attached to the diaryl moiety appeared at 4.37–4.43 ppm.Compounds19–30 were testedin vitro for anticancer activity by MTT assays against cervix uterus cancer cell Hela, human lung adenocarcinoma cell A-549, and human esophageal carcinoma cancer cell ECA-109. Cisplatin (DDP) was employed as a positive control in the assay. The results are presented in Table 1.Table 1
Antiproliferative activities (IC50) of compounds 19–30 against human cancer cell lines.
Compd.
Cell lines (IC50, μM)a
Hela
A-549
ECA-109
19
6.75 ± 0.40
11.29 ± 1.60
16.65 ± 1.98
20
4.06 ± 0.06
14.74 ± 2.68
8.23 ± 1.46
21
7.22 ± 1.72
16.72 ± 1.56
9.51 ± 1.22
22
11.58 ± 1.05
12.92 ± 1.17
12.26 ± 0.99
23
4.78 ± 0.67
13.34 ± 2.05
2.13 ± 0.35
24
15.03 ± 2.01
33.28 ± 4.35
8.74 ± 1.22
25
8.99 ± 1.21
20.00 ± 2.05
8.19 ± 0.75
26
5.21 ± 0.70
70.89 ± 5.33
2.60 ± 0.36
27
93.17 ± 5.00
97.42 ± 9.21
12.80 ± 1.98
28
>212
74.56 ± 8.73
153.35 ± 14.36
29
61.12 ± 6.85
28.19 ± 2.26
162.90 ± 11.78
30
>194
>194
>194
DDP
17.50 ± 0.83
30.89 ± 1.44
12.73 ± 0.70
aValues presented are means of three experiments.According to Table1, most of the title compounds19–30 exhibited moderate-to-potent antiproliferative activities against Hela, A-549, and ECA-109 cancer cell linesin vitro. It was noteworthy that the antiproliferative effects of compounds19–30 were more pronounced againstHela andECA-109 cells compared with A-549 cancer cells; some of them displayed higher activities (e.g.,19~26 with IC50 4.06~15.03 μM for Hela and20~26 with IC50 2.13~12.26 μM forECA-109) in comparison with cisplatin (IC50 17.50 μM forHela and 12.73 μM forECA-109). When the different substituents R
2 were introduced to the title compounds, the antiproliferative activities varied greatly. Compounds27~30 were less effective than19~26 on all cell lines and this result may be caused by the introduction of the CH3 group of R
2, which might lead to27~30 having a different conformation by comparison with19~26. Compounds20 and23 showed the most effective activity onHela andECA-109 and were 4-fold and 6-fold more active than DDP, respectively, which deserves further research.


## 3. Experimental

Melting points were carried out on a XRC-1 apparatus and are uncorrected (Beijing Technical Instrument Co.). Infrared spectra were recorded, from KBr discs of solid materials, on a Nicolex FI-IR-170 instrument. The1H NMR spectra were run on a Bruker AC500 (500 MHz). Compounds were dissolved in d6-DMSO, and chemical shifts were referenced to TMS. Mass spectra were obtained on a Agilent 1260 lon Trap LC/MS 500 analysis system. Elemental analyses were performed on a Thermo-Finnigan Flash EA 1112 instrument. TCL was carried out on silica gel UV-254 plates.


### 3.1. Synthesis of Compounds (15–18)

Compounds15–18 were synthesized from7–10 via11–14 according to literature methods [9], respectively. Compounds7–10 were obtained from diaryl ketones in the presence of sodium borohydride in methanol at reflux [8]. Compounds,11 [11],12 [8],13 [12],14 [13],15 [11],16 [8], and17 [12], were reported in literatures. But the characterized data of compound18 had not been reported.1-[(4-Bromophenyl)(phenyl)methyl]piperazine (
18
).  1H NMR (CDCl3, 400 MHz): δ 7.80 (t, 2H,J = 4.2 Hz, Ar), 7.56–7.66 (m, 5H, Ar), 7.47 (t, 2H,J = 7.6 Hz, Ar), 3.70 (m, 1H, CH), 2.94 (brs, 4H, NCH2), 2.88 (brs, 4H, NCH2).


### 3.2. Synthesis of Compounds (19–30): General Procedure

Triethylamine was added to the mixture of 1-diarylmethylpiperazine compounds15–18 (9.5 mmol) and compounds4–6 (10 mmol) in THF (50 mL) with acyl chloride (10 mmol) at 0°C; the mixture was kept under magnetic stirring for 30 min and then was warmed up to room temperature for 10~20 h at which time the progress of the reaction was monitored by thin-layer chromatography (ethyl acetate : alcohol = 9 : 1). The reaction mixture was then concentrated under reduced pressure and the residue was purified by column chromatography on silica gel (eluent: 2% EtOH in EtOAc) to obtain title compounds19–30.1-(4-Benzhydrylpiperazine-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione (
19
). A light gray solid (55%, mp 225~227°C). IR 3157, 3081, 3062, 2984, 1652, 1519, 1436, 1241, 957, 775 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.30 (s, 1H, NH), 8.13 (s, 1H, CH), 8.08 (d, 1H,J = 7.6 Hz, Ar), 7.53 (d, 1H,J = 7.8 Hz, Ar), 7.42 (d, 4H,J = 7.8 Hz, Ar), 7.17–7.31 (m, 8H, Ar), 4.37 (s, 1H, CH), 3.66 (t, 2H,J = 4.6 Hz, NCH2), 3.37 (t, 2H,J = 4.6 Hz, NCH2), 2.43 (t, 2H,J = 4.6 Hz, NCH2), 2.27 (t, 2H,J = 4.6 Hz, NCH2); ESI-MS,m/z(%): 424.4 [(M+H)+, 100]; Anal. calcd for C27H25N3O2: C, 76.57; H, 5.95; N, 9.92; O, 7.56; Found: C, 76.55; H, 5.94; N, 9.93; O, 7.57.1-(4-((4-Chlorophenyl)(phenyl)methyl)piperazine-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione (
20
). A white solid (60%, mp 241~243°C); IR 3156, 3099, 3063, 2983, 1617, 1523, 1463, 1242, 1001, 806 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.29 (s, 1H, NH), 8.13 (s, 1H, CH), 8.08 (d, 1H,J = 7.7 Hz, Ar), 7.53 (d, 1H,J = 7.8 Hz, Ar), 7.17–7.45 (m, 11H, Ar), 4.43 (s, 1H, CH), 3.46 (t, 2H,J = 4.6 Hz, NCH2), 3.37 (t, 2H,J = 4.6 Hz, NCH2), 2.42 (t, 2H,J = 4.6 Hz, NCH2), 2.26 (t, 2H,J = 4.6 Hz, NCH2); ESI-MS,m/z(%): 460.4 [(M+2)+, 50], 458.4 [(M+H)+, 100]; Anal. calcd for C27H24ClN3O2: C, 70.81; H, 5.28; N, 9.18; O, 6.99 Found: C, 70.80; H, 5.28; N, 9.17; O, 7.00.1-(4-((4-Fluorophenyl)(phenyl)methyl)piperazine-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione (
21
). A white solid (59%, mp 246~248°C); IR 3159, 3099, 3063, 2982, 1610, 1506, 1446, 1244, 999, 800 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.28 (s, 1H, NH), 8.13 (s, 1H, CH), 8.08 (d, 1H,J = 7.5 Hz, Ar), 7.53 (d, 1H,J = 7.9 Hz, Ar), 7.10–7.46 (m, 11H, Ar), 4.42 (s, 1H, CH), 3.65 (s, 2H, NCH2), 3.37 (s, 2H, NCH2), 2.42 (s, 2H, NCH2), 2.26 (s, 2H, NCH2); ESI-MS,m/z(%): 442.4 [(M+H)+, 100]; Anal. calcd for C27H24FN3O2: C, 73.45; H, 5.48; N, 9.52; O, 7.25; Found: C, 73.48; H, 5.47; N, 9.53; O, 7.24.1-(4-((4-Bromophenyl)(phenyl)methyl)piperazine-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione (
22
). A pale white solid (62%, mp 227~229°C); IR 3225, 3060, 2980, 1617, 1491, 1444, 1244, 997, 775 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.28 (s, 1H, NH), 8.13 (s, 1H, CH), 8.10 (d, 1H,J = 7.7 Hz, Ar), 7.53 (d, 1H,J = 7.8 Hz, Ar), 7.17–7.50 (m, 11H, Ar), 4.41 (s, 1H, CH), 3.66 (s, 2H, NCH2), 3.36 (t, 2H,J = 4.5 Hz, NCH2), 2.43 (t, 2H,J = 4.7 Hz, NCH2), 2.26 (s, 2H, NCH2); ESI-MS,m/z(%): 504.4 [(M+2)+, 100], 502.4 [(M+H)+, 100]; Anal. calcd for C27H24BrN3O2: C, 64.55; H, 4.81; N, 8.36; O, 6.37; Found: C, 64.53; H, 4.82; N, 8.35; O, 6.38.1-(4-Benzhydrylpiperazine-1-yl)-2-(5-bromo-1H-indol-3-yl)ethane-1,2-dione (
23
). A pale white solid (53%, mp 238~240°C); IR 3154, 3083, 3061, 2970, 1617, 1477, 1438, 1232, 998, 807 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.46 (s, 1H, NH), 8.19–8.21 (m, 2H, Ar+CH), 7.50 (d, 1H,J = 8.6 Hz, Ar), 7.18–7.43 (m, 11H, Ar), 4.38 (s, 1H, CH), 3.65 (s, 2H, NCH2), 3.37 (t, 2H,J = 4.7 Hz, NCH2), 2.43 (t, 2H,J = 4.7 Hz, NCH2), 2.27 (s, 2H, NCH2); ESI-MS,m/z(%): 504.4 [(M+2)+, 100], 502.4 [(M+H)+, 100]; Anal. calcd for C27H24BrN3O2: C, 64.55; H, 4.81; N, 8.36; O, 6.37; Found: C, 64.57; H, 4.80; N, 8.34; O, 6.38.1-(5-Bromo-1H-indol-3-yl)-2-(4-((4-chlorophenyl)(phenyl)methyl)piperazine-1-yl)ethane-1,2-dione (
24
). A white solid (81%, mp 240~242°C); IR 3164, 3061, 3028, 2922, 1620, 1489, 1447, 1234, 954, 804 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.46 (s, 1H, NH), 8.19–8.21 (m, 2H, Ar+CH), 7.50 (d, 1H,J = 8.6 Hz, Ar), 7.19–7.46 (m, 11H, Ar), 4.43 (s, 1H, CH), 3.65 (s, 2H, NCH2), 3.37 (s, 2H, NCH2), 2.42 (s, 2H, NCH2), 2.26 (s, 2H, NCH2); ESI-MS,m/z(%): 540.3 [(M+4)+, 30], 538.3 [(M+2)+, 100], 536.3 [(M+H)+, 70]; Anal. calcd for C27H23BrClN3O2: C, 60.41; H, 4.32; N, 7.83; O, 5.96; Found: C, 60.44; H, 4.31; N, 7.84; O, 5.95.1-(5-Bromo-1H-indol-3-yl)-2-(4-((4-fluorophenyl)(phenyl)methyl)piperazine-1-yl)ethane-1,2-dione (
25
). A white solid (82%, mp 251~253°C); IR 3156, 3064, 3031, 2964, 1624, 1478, 1437, 1232, 999, 806 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.46 (s, 1H), 8.20–8.21 (m, 2H, Ar+CH), 7.50 (d, 1H,J = 8.6 Hz, Ar), 7.11–7.47 (m, 11H, Ar), 4.42 (s, 1H, CH), 3.65 (s, 2H, NCH2), 3.36 (s, 2H, NCH2), 2.42 (s, 2H, NCH2), 2.26 (s, 2H, NCH2); ESI-MS,m/z(%): 522.4 [(M+2)+, 100], 520.4 [(M+H)+, 100]; Anal. calcd for C27H23BrFN3O2: C, 62.32; H, 4.45; N, 8.07; O, 6.15; Found: C, 62.33; H, 4.45; N, 8.08; O, 6.14.1-(5-Bromo-1H-indol-3-yl)-2-(4-((4-bromophenyl)(phenyl)methyl)piperazine-1-yl)ethane-1,2-dione (
26
). A white solid (78%, mp 227~229°C); IR 3158, 3082, 3060, 2970, 1617, 1477, 1437, 1233, 998, 807 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.46 (s, 1H, NH), 8.20–8.21 (m, 2H, Ar), 7.51 (d, 1H,J = 8.6 Hz, Ar), 7.18–7.49 (m, 11H, Ar), 4.41 (s, 1H, CH), 3.65 (s, 2H, NCH2), 3.37 (t, 2H,J = 4.5 Hz, NCH2), 2.42 (t, 2H,J = 4.6 Hz, NCH2), 2.27 (s, 2H, NCH2); ESI-MS,m/z(%): 584.2 [(M+4)+, 50], 582.3 [(M+2)+, 100], 580.3 [(M+H)+, 50]. Anal. calcd for C27H23Br2N3O2: C, 55.79; H, 3.99; N, 7.23; O, 5.50; Found: C, 55.81; H, 4.00; N, 7.22; O, 5.51.1-(4-Benzhydrylpiperazine-1-yl)-2-(2-methyl-1H-indol-3-yl)ethane-1,2-dione (
27
). A gray solid (78%, mp 199~201°C); IR 3180, 3103, 3058, 2974, 1610, 1492, 1457, 1246, 986, 790 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.22 (s, 1H, NH), 7.88 (s, 1H, Ar), 7.15–7.44 (m, 13H, Ar), 4.38 (s, 1H, CH), 3.66 (s, 2H, NCH2), 3.33 (s, 2H, NCH2), 2.59 (s, 3H, CH3), 2.41 (s, 2H, NCH2), 2.22 (s, 2H, NCH2); ESI-MS,m/z(%): 438.2 [(M+H)+, 100]; Anal. calcd for C28H27N3O2: C, 76.86; H, 6.22; N, 9.60; O, 7.31; Found: C, 76.89; H, 6.21; N, 9.62; O, 7.30.1-(4-((4-Chlorophenyl)(phenyl)methyl)piperazine-1-yl)-2-(2-methyl-1H-indol-3-yl)ethane-1,2-dione (
28
). A gray solid (85%, mp 180~182°C); IR 3180, 3103, 3058, 2974, 1610, 1492, 1457, 1247, 986, 790 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.22 (s, 1H, NH), 7.87 (s, 1H, Ar), 7.14–7.44 (m, 12H, Ar), 4.43 (s, 1H, CH), 3.66 (s, 2H, NCH2), 3.33 (s, 2H, NCH2), 2.59 (s, 3H, NCH2), 2.42 (s, 2H, NCH2), 2.24 (s, 2H, NCH2); ESI-MS,m/z(%): 474.3 [(M+2)+, 40], 472.5 [(M+H)+, 100]; Anal. calcd for C28H26ClN3O2: C, 71.25; H, 5.55; N, 8.90; O, 6.78; Found: C, 71.26; H, 5.54; N, 8.89; O, 6.79.1-(4-((4-Fluorophenyl)(phenyl)methyl)piperazine-1-yl)-2-(2-methyl-1H-indol-3-yl)ethane-1,2-dione (
29
). A gray solid (79%, mp >300°C); IR 3185, 3085, 3057, 2973, 1616, 1508, 1437, 1245, 986, 800 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.22 (s, 1H, NH), 7.88 (s, 1H, Ar), 7.11–7.46 (m, 12H, Ar), 4.39 (s, 1H, CH), 3.66 (s, 2H, NCH2), 3.33 (s, 2H, NCH2), 2.59 (s, 3H, CH3), 2.41 (s, 2H, NCH2), 2.22 (s, 2H, NCH2); ESI-MS,m/z(%): 456.5 [(M+2)+, 60], 457.4 [(M+2)+, 100]; Anal. calcd for C28H26FN3O2: C, 73.83; H, 5.75; N, 9.22; O, 7.02; Found: C, 73.81; H, 5.75; N, 9.21; O, 7.03.1-(4-((4-Bromophenyl)(phenyl)methyl)piperazine-1-yl)-2-(2-methyl-1H-indol-3-yl)ethane-1,2-dione (
30
). A gray solid (79%, mp 181~183°C); IR 3182, 3085, 3057, 2970, 1612, 1491, 1453, 1246, 986, 789 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.22 (s, 1H, NH), 7.87 (s, 1H, Ar), 7.15–7.49 (m, 12H, Ar), 4.39 (s, 1H, CH), 3.66 (s, 2H, NCH2), 3.38 (s, 2H, NCH2), 2.58 (s, 3H, CH3), 2.42 (s, 2H, NCH2), 2.24 (s, 2H, NCH2); ESI-MS,m/z(%): 518.4 [(M+2)+, 50], 516.4 [(M+H)+, 100]; Anal. calcd for C28H26BrN3O2: C, 65.12; H, 5.07; N, 8.14; O, 6.20; Found: C, 65.15; H, 5.06; N, 8.15; O, 6.19.


### 3.3. Treatment of Tumor Cell Lines

The antiproliferative activity of compounds19–30 against several human cancer cell lines was assayed by standard MTT assay procedures. Cells were cultured in DMEM medium at 37°C with 5% CO2 and 95% air, supplemented with 10% (V/V) bovine calf serum [14]. Cells were plated in 96-well plates at the density of 10,000 cells per well. After 24 h, the cells were treated with various concentrations of compounds from 1.0 to 100.0 μg/mL. Wells containing culture medium without cells were used as blanks and cisplatin was assayed at the same time as a positive control. The cells were further incubated for 72 h. The cytotoxicity was measured by adding 5 mg/mL of MTT to each well and incubated for another 4 h. The formazan crystals were dissolved by adding 150 μL of DMSO to each well. The optical density of each well was then measured on a microplate spectrophotometer at a wavelength of 570 nm. The IC50 value (μg/mL) was determined from plots of % viability against dose of compound added.The calculation formula of IC50 values has been revised as follows:(1)IC50=lg-1⁡Xm-iΣP-0.5,where X
m is the log value of the designed maximum concentration, i is the log value of dilution ratio, and Σ
P is the sum of growth inhibition rate of each group: (2)I%=100%1-EC,where I
(
%
) is the growth inhibition rate, E are the mean OD values for experimental groups, and C are the mean OD values for control groups.


## 3.1. Synthesis of Compounds (15–18)

Compounds15–18 were synthesized from7–10 via11–14 according to literature methods [9], respectively. Compounds7–10 were obtained from diaryl ketones in the presence of sodium borohydride in methanol at reflux [8]. Compounds,11 [11],12 [8],13 [12],14 [13],15 [11],16 [8], and17 [12], were reported in literatures. But the characterized data of compound18 had not been reported.1-[(4-Bromophenyl)(phenyl)methyl]piperazine (
18
).  1H NMR (CDCl3, 400 MHz): δ 7.80 (t, 2H,J = 4.2 Hz, Ar), 7.56–7.66 (m, 5H, Ar), 7.47 (t, 2H,J = 7.6 Hz, Ar), 3.70 (m, 1H, CH), 2.94 (brs, 4H, NCH2), 2.88 (brs, 4H, NCH2).


## 3.2. Synthesis of Compounds (19–30): General Procedure

Triethylamine was added to the mixture of 1-diarylmethylpiperazine compounds15–18 (9.5 mmol) and compounds4–6 (10 mmol) in THF (50 mL) with acyl chloride (10 mmol) at 0°C; the mixture was kept under magnetic stirring for 30 min and then was warmed up to room temperature for 10~20 h at which time the progress of the reaction was monitored by thin-layer chromatography (ethyl acetate : alcohol = 9 : 1). The reaction mixture was then concentrated under reduced pressure and the residue was purified by column chromatography on silica gel (eluent: 2% EtOH in EtOAc) to obtain title compounds19–30.1-(4-Benzhydrylpiperazine-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione (
19
). A light gray solid (55%, mp 225~227°C). IR 3157, 3081, 3062, 2984, 1652, 1519, 1436, 1241, 957, 775 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.30 (s, 1H, NH), 8.13 (s, 1H, CH), 8.08 (d, 1H,J = 7.6 Hz, Ar), 7.53 (d, 1H,J = 7.8 Hz, Ar), 7.42 (d, 4H,J = 7.8 Hz, Ar), 7.17–7.31 (m, 8H, Ar), 4.37 (s, 1H, CH), 3.66 (t, 2H,J = 4.6 Hz, NCH2), 3.37 (t, 2H,J = 4.6 Hz, NCH2), 2.43 (t, 2H,J = 4.6 Hz, NCH2), 2.27 (t, 2H,J = 4.6 Hz, NCH2); ESI-MS,m/z(%): 424.4 [(M+H)+, 100]; Anal. calcd for C27H25N3O2: C, 76.57; H, 5.95; N, 9.92; O, 7.56; Found: C, 76.55; H, 5.94; N, 9.93; O, 7.57.1-(4-((4-Chlorophenyl)(phenyl)methyl)piperazine-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione (
20
). A white solid (60%, mp 241~243°C); IR 3156, 3099, 3063, 2983, 1617, 1523, 1463, 1242, 1001, 806 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.29 (s, 1H, NH), 8.13 (s, 1H, CH), 8.08 (d, 1H,J = 7.7 Hz, Ar), 7.53 (d, 1H,J = 7.8 Hz, Ar), 7.17–7.45 (m, 11H, Ar), 4.43 (s, 1H, CH), 3.46 (t, 2H,J = 4.6 Hz, NCH2), 3.37 (t, 2H,J = 4.6 Hz, NCH2), 2.42 (t, 2H,J = 4.6 Hz, NCH2), 2.26 (t, 2H,J = 4.6 Hz, NCH2); ESI-MS,m/z(%): 460.4 [(M+2)+, 50], 458.4 [(M+H)+, 100]; Anal. calcd for C27H24ClN3O2: C, 70.81; H, 5.28; N, 9.18; O, 6.99 Found: C, 70.80; H, 5.28; N, 9.17; O, 7.00.1-(4-((4-Fluorophenyl)(phenyl)methyl)piperazine-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione (
21
). A white solid (59%, mp 246~248°C); IR 3159, 3099, 3063, 2982, 1610, 1506, 1446, 1244, 999, 800 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.28 (s, 1H, NH), 8.13 (s, 1H, CH), 8.08 (d, 1H,J = 7.5 Hz, Ar), 7.53 (d, 1H,J = 7.9 Hz, Ar), 7.10–7.46 (m, 11H, Ar), 4.42 (s, 1H, CH), 3.65 (s, 2H, NCH2), 3.37 (s, 2H, NCH2), 2.42 (s, 2H, NCH2), 2.26 (s, 2H, NCH2); ESI-MS,m/z(%): 442.4 [(M+H)+, 100]; Anal. calcd for C27H24FN3O2: C, 73.45; H, 5.48; N, 9.52; O, 7.25; Found: C, 73.48; H, 5.47; N, 9.53; O, 7.24.1-(4-((4-Bromophenyl)(phenyl)methyl)piperazine-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione (
22
). A pale white solid (62%, mp 227~229°C); IR 3225, 3060, 2980, 1617, 1491, 1444, 1244, 997, 775 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.28 (s, 1H, NH), 8.13 (s, 1H, CH), 8.10 (d, 1H,J = 7.7 Hz, Ar), 7.53 (d, 1H,J = 7.8 Hz, Ar), 7.17–7.50 (m, 11H, Ar), 4.41 (s, 1H, CH), 3.66 (s, 2H, NCH2), 3.36 (t, 2H,J = 4.5 Hz, NCH2), 2.43 (t, 2H,J = 4.7 Hz, NCH2), 2.26 (s, 2H, NCH2); ESI-MS,m/z(%): 504.4 [(M+2)+, 100], 502.4 [(M+H)+, 100]; Anal. calcd for C27H24BrN3O2: C, 64.55; H, 4.81; N, 8.36; O, 6.37; Found: C, 64.53; H, 4.82; N, 8.35; O, 6.38.1-(4-Benzhydrylpiperazine-1-yl)-2-(5-bromo-1H-indol-3-yl)ethane-1,2-dione (
23
). A pale white solid (53%, mp 238~240°C); IR 3154, 3083, 3061, 2970, 1617, 1477, 1438, 1232, 998, 807 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.46 (s, 1H, NH), 8.19–8.21 (m, 2H, Ar+CH), 7.50 (d, 1H,J = 8.6 Hz, Ar), 7.18–7.43 (m, 11H, Ar), 4.38 (s, 1H, CH), 3.65 (s, 2H, NCH2), 3.37 (t, 2H,J = 4.7 Hz, NCH2), 2.43 (t, 2H,J = 4.7 Hz, NCH2), 2.27 (s, 2H, NCH2); ESI-MS,m/z(%): 504.4 [(M+2)+, 100], 502.4 [(M+H)+, 100]; Anal. calcd for C27H24BrN3O2: C, 64.55; H, 4.81; N, 8.36; O, 6.37; Found: C, 64.57; H, 4.80; N, 8.34; O, 6.38.1-(5-Bromo-1H-indol-3-yl)-2-(4-((4-chlorophenyl)(phenyl)methyl)piperazine-1-yl)ethane-1,2-dione (
24
). A white solid (81%, mp 240~242°C); IR 3164, 3061, 3028, 2922, 1620, 1489, 1447, 1234, 954, 804 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.46 (s, 1H, NH), 8.19–8.21 (m, 2H, Ar+CH), 7.50 (d, 1H,J = 8.6 Hz, Ar), 7.19–7.46 (m, 11H, Ar), 4.43 (s, 1H, CH), 3.65 (s, 2H, NCH2), 3.37 (s, 2H, NCH2), 2.42 (s, 2H, NCH2), 2.26 (s, 2H, NCH2); ESI-MS,m/z(%): 540.3 [(M+4)+, 30], 538.3 [(M+2)+, 100], 536.3 [(M+H)+, 70]; Anal. calcd for C27H23BrClN3O2: C, 60.41; H, 4.32; N, 7.83; O, 5.96; Found: C, 60.44; H, 4.31; N, 7.84; O, 5.95.1-(5-Bromo-1H-indol-3-yl)-2-(4-((4-fluorophenyl)(phenyl)methyl)piperazine-1-yl)ethane-1,2-dione (
25
). A white solid (82%, mp 251~253°C); IR 3156, 3064, 3031, 2964, 1624, 1478, 1437, 1232, 999, 806 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.46 (s, 1H), 8.20–8.21 (m, 2H, Ar+CH), 7.50 (d, 1H,J = 8.6 Hz, Ar), 7.11–7.47 (m, 11H, Ar), 4.42 (s, 1H, CH), 3.65 (s, 2H, NCH2), 3.36 (s, 2H, NCH2), 2.42 (s, 2H, NCH2), 2.26 (s, 2H, NCH2); ESI-MS,m/z(%): 522.4 [(M+2)+, 100], 520.4 [(M+H)+, 100]; Anal. calcd for C27H23BrFN3O2: C, 62.32; H, 4.45; N, 8.07; O, 6.15; Found: C, 62.33; H, 4.45; N, 8.08; O, 6.14.1-(5-Bromo-1H-indol-3-yl)-2-(4-((4-bromophenyl)(phenyl)methyl)piperazine-1-yl)ethane-1,2-dione (
26
). A white solid (78%, mp 227~229°C); IR 3158, 3082, 3060, 2970, 1617, 1477, 1437, 1233, 998, 807 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.46 (s, 1H, NH), 8.20–8.21 (m, 2H, Ar), 7.51 (d, 1H,J = 8.6 Hz, Ar), 7.18–7.49 (m, 11H, Ar), 4.41 (s, 1H, CH), 3.65 (s, 2H, NCH2), 3.37 (t, 2H,J = 4.5 Hz, NCH2), 2.42 (t, 2H,J = 4.6 Hz, NCH2), 2.27 (s, 2H, NCH2); ESI-MS,m/z(%): 584.2 [(M+4)+, 50], 582.3 [(M+2)+, 100], 580.3 [(M+H)+, 50]. Anal. calcd for C27H23Br2N3O2: C, 55.79; H, 3.99; N, 7.23; O, 5.50; Found: C, 55.81; H, 4.00; N, 7.22; O, 5.51.1-(4-Benzhydrylpiperazine-1-yl)-2-(2-methyl-1H-indol-3-yl)ethane-1,2-dione (
27
). A gray solid (78%, mp 199~201°C); IR 3180, 3103, 3058, 2974, 1610, 1492, 1457, 1246, 986, 790 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.22 (s, 1H, NH), 7.88 (s, 1H, Ar), 7.15–7.44 (m, 13H, Ar), 4.38 (s, 1H, CH), 3.66 (s, 2H, NCH2), 3.33 (s, 2H, NCH2), 2.59 (s, 3H, CH3), 2.41 (s, 2H, NCH2), 2.22 (s, 2H, NCH2); ESI-MS,m/z(%): 438.2 [(M+H)+, 100]; Anal. calcd for C28H27N3O2: C, 76.86; H, 6.22; N, 9.60; O, 7.31; Found: C, 76.89; H, 6.21; N, 9.62; O, 7.30.1-(4-((4-Chlorophenyl)(phenyl)methyl)piperazine-1-yl)-2-(2-methyl-1H-indol-3-yl)ethane-1,2-dione (
28
). A gray solid (85%, mp 180~182°C); IR 3180, 3103, 3058, 2974, 1610, 1492, 1457, 1247, 986, 790 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.22 (s, 1H, NH), 7.87 (s, 1H, Ar), 7.14–7.44 (m, 12H, Ar), 4.43 (s, 1H, CH), 3.66 (s, 2H, NCH2), 3.33 (s, 2H, NCH2), 2.59 (s, 3H, NCH2), 2.42 (s, 2H, NCH2), 2.24 (s, 2H, NCH2); ESI-MS,m/z(%): 474.3 [(M+2)+, 40], 472.5 [(M+H)+, 100]; Anal. calcd for C28H26ClN3O2: C, 71.25; H, 5.55; N, 8.90; O, 6.78; Found: C, 71.26; H, 5.54; N, 8.89; O, 6.79.1-(4-((4-Fluorophenyl)(phenyl)methyl)piperazine-1-yl)-2-(2-methyl-1H-indol-3-yl)ethane-1,2-dione (
29
). A gray solid (79%, mp >300°C); IR 3185, 3085, 3057, 2973, 1616, 1508, 1437, 1245, 986, 800 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.22 (s, 1H, NH), 7.88 (s, 1H, Ar), 7.11–7.46 (m, 12H, Ar), 4.39 (s, 1H, CH), 3.66 (s, 2H, NCH2), 3.33 (s, 2H, NCH2), 2.59 (s, 3H, CH3), 2.41 (s, 2H, NCH2), 2.22 (s, 2H, NCH2); ESI-MS,m/z(%): 456.5 [(M+2)+, 60], 457.4 [(M+2)+, 100]; Anal. calcd for C28H26FN3O2: C, 73.83; H, 5.75; N, 9.22; O, 7.02; Found: C, 73.81; H, 5.75; N, 9.21; O, 7.03.1-(4-((4-Bromophenyl)(phenyl)methyl)piperazine-1-yl)-2-(2-methyl-1H-indol-3-yl)ethane-1,2-dione (
30
). A gray solid (79%, mp 181~183°C); IR 3182, 3085, 3057, 2970, 1612, 1491, 1453, 1246, 986, 789 cm−1; 1H NMR (d6-DMSO, 500 MHz): δ 12.22 (s, 1H, NH), 7.87 (s, 1H, Ar), 7.15–7.49 (m, 12H, Ar), 4.39 (s, 1H, CH), 3.66 (s, 2H, NCH2), 3.38 (s, 2H, NCH2), 2.58 (s, 3H, CH3), 2.42 (s, 2H, NCH2), 2.24 (s, 2H, NCH2); ESI-MS,m/z(%): 518.4 [(M+2)+, 50], 516.4 [(M+H)+, 100]; Anal. calcd for C28H26BrN3O2: C, 65.12; H, 5.07; N, 8.14; O, 6.20; Found: C, 65.15; H, 5.06; N, 8.15; O, 6.19.


## 3.3. Treatment of Tumor Cell Lines

The antiproliferative activity of compounds19–30 against several human cancer cell lines was assayed by standard MTT assay procedures. Cells were cultured in DMEM medium at 37°C with 5% CO2 and 95% air, supplemented with 10% (V/V) bovine calf serum [14]. Cells were plated in 96-well plates at the density of 10,000 cells per well. After 24 h, the cells were treated with various concentrations of compounds from 1.0 to 100.0 μg/mL. Wells containing culture medium without cells were used as blanks and cisplatin was assayed at the same time as a positive control. The cells were further incubated for 72 h. The cytotoxicity was measured by adding 5 mg/mL of MTT to each well and incubated for another 4 h. The formazan crystals were dissolved by adding 150 μL of DMSO to each well. The optical density of each well was then measured on a microplate spectrophotometer at a wavelength of 570 nm. The IC50 value (μg/mL) was determined from plots of % viability against dose of compound added.The calculation formula of IC50 values has been revised as follows:(1)IC50=lg-1⁡Xm-iΣP-0.5,where X
m is the log value of the designed maximum concentration, i is the log value of dilution ratio, and Σ
P is the sum of growth inhibition rate of each group: (2)I%=100%1-EC,where I
(
%
) is the growth inhibition rate, E are the mean OD values for experimental groups, and C are the mean OD values for control groups.


## 4. Conclusion

A series of indoleoxoacetic piperazine derivatives19~30 were synthesized and characterized. Thein vitro antitumor activities of these compounds against Hela, A-549, and ECA-109 cells were evaluated. The effects of compounds19–26 are all superior to DDP against all tested cancer cell lines, and compounds20,19, and23 showed the best antiproliferative effect on Hela, A-549, and ECA-109 cells, respectively. These results encourage us to synthesize additional new indoleoxoacetic piperazine derivatives with the expected more potent antitumor activity.



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*Source: 4617454-2016-07-10.xml*