Synthesis and anticancer activity of 5,6,8,13-tetrahydro-7Hnaphtho[2,3-a] [3]-benzazepine-8,13-diones

Article abstract of DOI:10.1007/s12272-012-0502-3

A series of naphthoquinones fused benzazepines, 5,6,8,13-tetrahydro-7H- naphtho[2,3-a][3]- benzazepine-8,13-diones, were synthesized and evaluated for their anticancer activity against four cell lines; human breast carcinoma cell line, human cervix carcinoma cell line, human hepatocellular carcinoma cell line and human keratinocyte cell line. The results showed that 5,6,8,13-tetrahydro- 2,3,4,9-tetramethoxy-7H-naphtho[2,3-a][3]benzazepine-8,13-dione 4g and 5,6,8,13-tetrahydro-2,3,9-trimethoxy-7H-naphtho[2,3-a][3]benzazepine-8,13-dione 4h have significant cytotoxicity against a hepatocellular carcinoma cell line with IC₅₀ = 3.5 μg/mL and 3.0 μg/mL, respectively.

Full text of DOI:10.1007/s12272-012-0502-3

Arch Pharm Res Vol 35, No 5, 769-777, 2012
DOI 10.1007/s12272-012-0502-3
Synthesis and Anticancer Activity of 5,6,8,13-tetrahydro-7H-
naphtho[2,3-a][3]-benzazepine-8,13-diones
Weerachai Phutdhawong1, Gedsirin Eksinitkun2, Wanwikar Ruensumran1, Thongchai Taechowisan3, and
Waya S. Phutdhawong2
1Department of Chemistry, Faculty of Liberal Arts and Science, Kasetsart University, Kampang Saen campus, Nakhon
2
Pathom, 73140, Thailand, Department of Chemistry, Faculty of Science, Silpakorn University, Nakorn Pathom, 73000,
3
Thailand, and Department of Microbiology, Faculty of Science, Silpakorn University, Nakhon Pathom, 73000, Thailand
(Received May 23, 2011/Revised August 29, 2011/Accepted October 11, 2011)
A series of naphthoquinones fused benzazepines, 5,6,8,13-tetrahydro-7H-naphtho[2,3-a][3]-
benzazepine-8,13-diones, were synthesized and evaluated for their anticancer activity against
four cell lines; human breast carcinoma cell line, human cervix carcinoma cell line, human
hepatocellular carcinoma cell line and human keratinocyte cell line. The results showed that
5,6,8,13-tetrahydro-2,3,4,9-tetramethoxy-7
5,6,8,13-tetrahydro-2,3,9-trimethoxy-7 -naphtho[2,3-
nificant cytotoxicity against a hepatocellular carcinoma cell line with IC50 = 3.5
g/mL, respectively.
H
-naphtho[2,3-
][3]benzazepine-8,13-dione 4h have sig-
g/mL and 3.0
a][3]benzazepine-8,13-dione 4g and
H
a
µ
µ
Key words: Naphthoquinones, Aminonaphthoquinones, Benzazepine, Anticancer agents
(Phutdhawong et al., 2009). Further studies of the
cytotoxicity in regards to these types of compounds
INTRODUCTION
Heterocyclic naphthoquinones are of considerable against several tumor cell lines showed a moderate to
interest as they possess biological effects especially high selectivity against NCI-H18-small cell lung
antitumor properties (Tandon et al., 2004; Miguel cancer and human hepatocellular carcinoma cell line
del Corral et al., 2005, 2006a, 2006b; Yamashita et (HepG2) (Ruensamran, 2009). All of these results pro-
al., 2007; Park et al., 2010). The mechanism of mpted us to synthesize 5,6,8,13-tetrahydro-7
H-naphtho
action of the quinone derivatives is well documented [2,3- ][3]-benzazepine-8,13-diones, in which the na-
a
and known to inhibit topoisomerase enzyme via DNA phthoquinones are fused with a benzazepine moiety,
intercalation and reduction of the quinone moiety by as potential anticancer agents.
oxido-reductases (DT-diaphorase) in the process of
Previous approaches to azepine-fused naphthoqui-
redox cycling (Lee et al., 2003; Miguel del Corral et al., nones have been based on two strategies. The first in-
2006a; Valderrama et al., 2008). Studies on the struc- volved the intramolecular cyclization of phenol deriva-
ture-activity relationship of heterocyclic naphthoqui- tives bearing aminonaphthoquinones with hyperval-
nones have revealed that the cytotoxic activity relies ent iodine reagent (Kita et al., 1996). The second strat-
upon the number and position of nitrogen atoms in egy relied on the Prins cyclization of amino-lapachol
the heterocyclic quinones (Kim et al., 2004). As part of derivatives (Camara et al., 2002). Of the two strategies
our ongoing research to identify structurally novel to obtain azepinonaphthoquinones, we have chosen
bioactive compounds, we recently reported on the syn- the palladium (II)-catalysted oxidative cyclization of
thesis and inflammatory activity concerning a series the aminonaphthoquinone derivatives since this pro-
of naphtho[2,3-
d
]-azepino[4,5-
b
]indole-9,14-diones cedure has been reported to provide very good yields per-
taining to the cyclization of naphthoquinone derivatives
Correspondence to: Waya S. Phutdhawong, Department of
Chemistry, Faculty of Science, Silpakorn University, Thailand
Tel: 66-34255797
(Knölker and O'Sullivan, 1994; Miguel del Corral et
al., 2006b; Phutdhawong et al., 2009).
E-mail: sengwaya@su.ac.th
769

770
W. Phutdhawong et al.
4.13 (t,
J
= 6.9 Hz, 2H, N-CH2), 6.75-6.83 (m, 3H,
MATERIALS AND METHODS
ArH), 7.62 (dd,
Melting points (m.p.) were determined on a Stuart 1.2, 7.5 Hz, 1H, ArH), 8.00 (dd,
Scientific SMP 2 melting point apparatus and were ArH), 8.14 (dd,
= 1.2, 7.5 Hz, 1H, ArH); 13C-NMR
uncorrected. Infrared spectra were recorded on CH2Cl2- (CDCl3) 36.6, 46.4, 55.8, 55.9, 111.5, 112.1, 120.9,
J
= 1.5, 7.5 Hz, 1H, ArH), 7.71 (dd,
J =
J
= 1.5, 7.5 Hz, 1H,
J
δ
films with a Perkin Elmer Spectrum GX FT-IR spec- 126.8, 126.9, 129.8, 130.2x2C, 132.3, 132.4, 134.8, 146.6,
trophotometer. 1H- and 13C-NMR spectra were recorded 147.9, 149.2, 176.3, 179.9; HRES-MS m/z calcd for
on (D) chloroform solutions at 300 MHz for 1H and 75 [M+H]+ C20H19BrNO4: 416.0497, found: 416.0574.
MHz for 13C with a Bruker AVANCE 300 spectrometer.
Tetramethylsilane was used as the internal standard. 3-Bromo-2-(3-methoxyphenethylamino)-1,4-naph-
Mass spectra were recorded on a POLARIS Q or thoquinone (3c)
HEWLETT PACKARD 5973 mass spectrometer.
According to the general procedure; treatment of 2,3-
dibromo-1,4-naphthoquinone (1a) (0.30 g, 0.95 mmol)
in DCM (2 mL) with phenethylamine (2c) (0.17 g, 1.14
mmol) in EtOH (6 mL) gave 3c as a red solid (0.22 g,
General procedure for the synthesis of ami-
nonaphthoquinones (3a-h)
To a solution of naphthoquinones (
1
) (1 equiv.) in 60%), m.p. 137-139oC; IR (CH2Cl2): νmax/cm−1, 3427,
1
dichloromethane (DCM, 2 mL) was added portion wise 1735, 1682; H-NMR (CDCl3)
δ
2.89 (dd,
J
= 7.2, 6.9
= 6.9
equiv.) in EtOH (2 mL). The reaction mixture was Hz, 2H, N-CH2), 6.04 (br s, 1H, NH), 6.71-6.78 (m, 3H,
stirred for 15 h at room temperature. In addition, the ArH), 7.15-7.20 (m, 1H, ArH), 7.55 (td, = 7.5, 0.9 Hz,
solvent was evaporated in vacuo to give the crude pro- 1H, ArH), 7.64 (td, = 7.5, 1.2 Hz, 1H, ArH), 7.93 (d,
duct, which was purified by flash chromatography on = 7.5 Hz, 1H, ArH), 8.07 (d, = 7.5 Hz, 1H, ArH);
silica gel (hexane-EtOAc 6:1) to afford pure aminonaph- 13C-NMR (75 MHz, CDCl3)
37.1, 46.2, 55.2, 112.2,
a solution of the appropriate phenethylamines (2) (1.2 Hz, 2H, C-CH2), 3.72 (s, 3H, ArOCH3), 4.07 (q, J
J
J
J
J
δ
thoquinones 3a-h
.
114.6, 121.2, 126.9, 127.0, 128.2, 129.9, 132.4, 134.5,
134.8, 139.3, 142.6, 146.5, 159.9, 176.4, 180.0; HRES-
MS m/z calcd for [M+H]+ C19H17BrNO3: 386.0392,
found: 386.0407.
3-Bromo-2-(2,3,4-trimethoxyphenethylamino)-1,4-
naphthoquinone (3a)
The following general procedure applied: treatment of
2,3-dibromo-1,4-naphthoquinone (1a) (0.50 g, 1.59 mmol) 2-(2-(Benzo[d][1,3]dioxol-5-yl)ethylamino)-3-bromo-
in DCM (3 mL) with phenethylamine (2a) (0.44 g, 2.07 1,4-naphthoquinone (3d)
mmol) in EtOH (15 mL) gave 3a as a viscous solid According to the general procedure; treatment of 2,3-
(0.34 g, 49%), IR (CH2Cl2): νmax/cm−1, 3429, 1735, 1638; dibromo-1,4-naphthoquinone (1a) (0.20 g, 0.63 mmol)
1H-NMR (CDCl3)
δ 2.93 (t, J = 6.6 Hz, 2H, C-CH2), in DCM (2 mL) with phenethylamine (2d) (0.13 g, 0.76
3.83 (s, 3H, ArOCH3), 3.86 (s, 3H, ArOCH3), 3.93 (s, mmol) in EtOH (6 mL) gave 3d as a red solid (0.19 g,
3H, ArOCH3), 4.05-4.13 (m, 2H, N-CH2), 6.61 (d,
8.4 Hz, 1H, ArH), 6.87 (d,
(td, = 1.2, 7.5 Hz, 1H, ArH), 7.69 (td,
1H, ArH), 7.99 (d, = 7.5 Hz, ArH), 8.13 (d,
1H, ArH); 13C-NMR (CDCl3)
J
=
75%), m.p. 145-178oC; IR (CH2Cl2): νmax/cm−1, 3414, 1734,
1
J
= 8.4 Hz, 1H, ArH), 7.60 1608; H-NMR (CDCl3)
δ
2.82 (t,
= 6.8 Hz, 2H, N-CH2), 5.84 (s, 2H,
= 7.5 Hz, OCH2O), 5.97 (br s, 1H, NH), 6.59-6.68 (m, 3H, ArH),
J = 7.0 Hz, 2H, C-
J
J = 1.2, 7.5 Hz, CH2), 4.00 (q, J
J
J
δ
29.9, 45.5, 54.9, 59.8, 7.53 (t,
J
= 7.5 Hz, 1H, ArH), 7.62 (t,
= 7.5 Hz, 1H, ArH), 8.04 (d,
131.7, 133.7, 133.9, 141.2, 146.1, 150.9, 141.9, 175.4, Hz, 1H, ArH); 13C-NMR (CDCl3)
32.8, 45.4, 99.9, 107.5,
179.1; HRES-MS m/z calcd for [M+H]+ C21H21BrNO5: 108.0, 120.9, 125.8, 126.0, 126.2, 130.3, 130.9, 131.3,
J
= 7.5 Hz, 1H,
89.9, 106.4, 122.8, 123.5, 125.7, 125.9, 128.9, 131.2, ArH), 7.90 (d,
J
J
= 7.5
δ
446.0603, found: 446.0685.
131.4, 131.7, 133.8, 146.5, 146.9, 175.4, 179.0; HRES-MS
m/z calcd for [M+H]+ C19H14BrNO4: 400.0184, found:
400.0252.
3-Bromo-2-(3,4-dimethoxyphenethylamino)-1,4-
naphthoquinone (3b)
According to the general procedure; treatment of 2,3- 2-(3-(Benzyloxy)-4-methoxyphenethylamino)-3-
dibromo-1,4-naphthoquinone (1a) (0.71 g, 2.25 mmol) bromo-1,4-naphthoquinone (3e)
in DCM (4 mL) with phenethylamine (2b) (0.37 mL, According to the general procedure; treatment of 2,3-
2.25 mmol) in EtOH (12 mL) gave 3b as a red solid dibromo-1,4-naphthoquinone (1a) (0.90 g, 2.85 mmol)
(0.61 g, 66%), m.p. 154-158oC; IR (CH2Cl2): νmax/cm−1, in DCM (5 mL) with phenethylamine (2e) (0.88 g, 3.42
3423, 1735, 1679; 1H-NMR (CDCl3)
δ
2.93 (t,
J = 6.9 Hz, mmol) in EtOH (25 mL) gave 3e as a viscous solid
2H, C-CH2), 3.85 (s, 3H, ArOCH3), 3.88 (s, 3H, ArOCH3), (0.51 g, 36%), IR (CH2Cl2): νmax/cm−1, 3427, 1734, 1604;

Synthesis and Anticancer Activity of Naphthoazepines
771
1H-NMR (CDCl3)
3.86 (s, 3H, ArOCH3), 4.04 (td,
CH2), 5.15 (s, 2H, O-CH2), 6.06 (br s, 1H, NH), 6.77- According to the general procedure; treatment of 5-
6.83 (m, 3H, ArH), 7.24-7.44 (m, 5H, ArH), 7.62 (td, methoxy-2,3-dibromo-1,4-naphthoquinone (1b) (0.50
= 1.5, 7.5 Hz, 1H, ArH), 7.71 (td, = 1.5, 7.5 Hz, 1H, g, 1.45 mmol) in EtOH (6.6 mL) with phenethylamine
ArH), 8.00 (d, = 7.5 Hz, 1H, ArH), 8.14 (d,
Hz, 1H, ArH); 13C-NMR (CDCl3)
δ
2.86 (t,
J
= 6.9 Hz, 2H, C-CH2), 3-Bromo-2-(3,4-dimethoxyphenethylamino)-5-
= 6.6, 6.9 Hz, 1H, N- methoxy-1,4-naphthoquinone (3h)
J
J
J
J
J
= 7.5
(2h) (0.34 g, 1.87 mmol) in EtOH (0.5 mL) gave 3h as
δ
36.5, 46.3, 56.1, a red solid (0.41 g, 64%); m.p. 154-156oC; IR (CH2Cl2):
71.1, 112.2, 114.9, 121.6, 126.8, 127.0, 127.3 (x 2C), νmax/cm−1, 3302, 1674, 1574, 1515; H-NMR (CDCl3)
δ
1
127.5, 127.8, 127.9, 128.5x2C, 130.1, 132.4, 134.8, 137.0, 2.92 (t,
146.6, 148.3, 148.7, 149.9, 176.4, 179.3; HRES-MS m/ 3.87 (s, 3H, ArOCH3), 3.99 (s, 3H, ArOCH3), 4.12 (q,
calcd for [M+H]+ C21H21BrNO5: 492.0810, found: = 6.2 Hz, 2H, N-CH2), 6.26 (br s, 1H, NH), 6.74-6.77
J = 6.5 Hz, 2H, C-CH2), 3.84 (s, 3H, ArOCH3),
J
z
492.0909.
(m, 2H, ArH), 7.18 (d,
= 7.9 Hz, 1H, ArH), 7.81 (d,
NMR (CDCl3) 36.6, 46.4, 55.9, 56.3, 111.5, 111.9,
116.2, 117.4, 118.5, 119.3, 119.9, 120.9, 130.1, 137.7,
J
= 8.3 Hz, 1H, ArH), 7.63 (d,
J
J
= 7.3 Hz, 1H, ArH); 13C-
2-(3,4-bis(Benzyloxy)phenethylamino)-3-bromo-
1,4-naphthoquinone (3f)
δ
According to the general procedure; treatment of 2,3- 136.0, 136.3, 147.9, 149.1, 160.1, 176.2, 178.1; HRES-
dibromo-1,4-naphthoquinone (1a) (0.63 g, 2.00 mmol) MS m/z calcd for [M+H]+ C21H20BrNO5: 446.0603,
in EtOH (9 mL) with phenethylamine (2f) (0.87 g, 2.60 found: 446.0574.
mmol) in EtOH (1 mL) gave 3f as a red solid (0.75 g,
72%), m.p. 79-81oC; IR (CH2Cl2): νmax/cm−1, 3332, 1674,
General procedure for the palladium-catalyzed
oxidative cyclization
1
1600, 1574, 1514; H-NMR (CDCl3)
δ
2.85 (t,
J = 6.9
Hz, 2H, C-CH2), 4.02 (q,
J
= 6.6 Hz, 2H, N-CH2), 5.10
A mixture of 3-bromo-2-substituted amino-1,4-na-
(s, 2H, O-CH2), 5.14 (s, 2H, O-CH2), 6.04 (br s, 1H, phthoquinones (3a-h) (1 equiv.), palladium acetate
NH), 6.74 (dd, = 1.9, 8.1 Hz, 1H, ArH), 6.81 (d, (Pd(OAc)2) (0.10 equiv.), triphenylphosphine (PPh3)
1.9 Hz, 1H, ArH), 6.88 (d, = 8.1 Hz, 1H, ArH), 7.24- (0.10 equiv.) and potassium carbonate (3 equiv.) in dry
7.43 (m, 10H, ArH), 7.58 (td,
= 1.3, 7.5 Hz, 1H, ArH), toluene was stirred in a sealed tube at 120oC for 36 h
7.67 (td, = 1.3, 7.5 Hz, 1H, ArH), 7.96 (dd, = 1.2, 7.5 under an argon atmosphere. After cooling, the reaction
Hz, 1H, ArH), 8.11 (dd,
= 1.2, 7.5 Hz, 1H, ArH); 13C- mixture was poured into water, and extracted with
NMR (CDCl3) 36.5, 46.3, 71.4x2C, 115.4, 115.9, 121.8, EtOAc. Furthermore, the extract was washed with
J
J =
J
J
J
J
J
δ
126.8, 126.9, 127.3, 127.4*2, 127.8, 127.9, 128.2, 128.3, water, dried (Na2SO4), evaporated in vacuo and subject-
128.5x2C, 129.8, 131.1, 132.3, 132.4, 134.8, 137.3, 137.4, ed to flash column chromatography on silica gel (hexane-
146.5, 147.9, 149.2, 176.3, 179.9; HRES-MS m/z calcd ethyl acetate 6:1).
for [M+H]+ C32H26BrNO4: 568.1123, found: 568.1060.
Cyclization of 3-bromo-2-(2,3,4-trimethoxyphen-
3-Bromo-2-(2,3,4-trimethoxyphenethylamino)-5-
methoxy-1,4-naphthoquinone (3g)
ethylamino)-1,4-naphthoquinone (3a)
According to the general procedure; treatment of 3a
According to the general procedure; treatment of 5- (0.16 g, 0.36 mmol) with Pd(OAc)2 (8.3 mg, 0.037
methoxy-2,3-dibromo-1,4-naphthoquinone (1b) (0.20 mmol), PPh3 (19 mg, 0.074 mmol) and K2CO3 (0.15 g,
g, 0.58 mmol) in EtOH (6.6 mL) with phenethylamine 1.08 mmol) in toluene (4 mL) gave in the first column
(
2g) (0.16 g, 0.76 mmol) in EtOH (0.5 mL) gave 3g as fraction 5,6,8,13-tetrahydro-2,3,4-trimethoxy-7H-na-
a red solid (0.17 g, 62%); m.p. 113-115oC; IR (CH2Cl2): phtho[2,3-
a][3]benzazepine-8,13-dione 4a (7.7 mg, 18%)
νmax/cm−1, 3303, 1672, 1601, 1578; H-NMR (CDCl3)
2.92 (t,
δ
as a purple viscous solid; IR (CH2Cl2): νmax/cm−1, 3429,
1
1
J
= 6.7 Hz, 2H, C-CH2), 3.82 (s, 3H, ArOCH3), 1733, 1635; H-NMR (CDCl3)
δ
3.12-3.14 (m, 2H, C-
3.86 (s, 3H, ArOCH3), 3.92 (s, 3H, ArOCH3), 3.98 (s, CH2), 3.81-3.84 (m, 2H, N-CH2), 3.87 (s, 3H, ArOCH3),
3H, ArOCH3), 4.08 (q, = 6.6 Hz, 2H, N-CH2), 6.60 (d, 3.89 (s, 3H, ArOCH3), 3.94 (s, 3H, ArOCH3), 6.57 (br s,
= 8.5 Hz, 1H, ArH), 6.87 (d, = 8.4 Hz, 1H, ArH), 1H, N-H), 6.94 (s, 1H, H-13), 7.65 (dd, = 1.3, 7.6 Hz,
= 8.5 Hz, 1H, ArH), 7.62 (dd, = 8.0, 8.1 Hz, 1H, ArH), 7.77 (dd, = 1.3, 7.6 Hz, 1H, ArH), 8.09 (d,
= 7.5 Hz, 1H, ArH); 13C-NMR
= 7.6 Hz, 1H, ArH), 8.22 (d, = 7.6 Hz, 1H, ArH);
31.1, 55.9, 56.4, 56.5, 60.7, 60.9, 107.3, 13C-NMR (CDCl3)
25.3, 51.9, 56.0, 60.9, 61.6, 112.4,
J
J
J
J
7.17 (d,
J
J
J
1H, ArH), 7.80 (d,
(CDCl3)
J
J
J
δ
δ
116.1, 119.0, 119.8, 123.7, 124.4, 124.5, 124.8, 134.7, 113.1, 125.9, 126.9, 128.2, 128.6, 130.2, 132.1, 133.9,
135.8, 142.2, 151.9, 160.0, 176.2, 178.3; HRES-MS m/ 134.8, 141.7, 146.7, 149.6, 150.9, 182.2, 182.3; HRES-
z
calcd for [M+H]+ C22H22BrNO6: 476.0709, found: MS m/z calcd for [M+H]+ C21H20NO5: 366.1341, found:
476.0668.
366.1415.

772
W. Phutdhawong et al.
The second fraction gave 2-(2,3,4-trimethoxypheneth- (0.13 g, 0.32 mmol) with Pd(OAc)2 (7.4 mg, 0.032 mmol),
ylamino)naphthalene-1,4-dione 5a (13.3 mg, 31%) as a PPh3 (17 mg, 0.066 mmol) and K2CO3 (0.13 g, 0.96
orange solid m.p. 142-145oC; IR (CH2Cl2): νmax/cm−1, mmol) in toluene (3.8 mL) gave in the first fraction of
3388, 1735, 1679; 1H-NMR (CDCl3)
6.6 Hz, 2H, C-CH2), 3.36 (t, = 6.9 Hz, 1H, N-CH2),
3.85 (s, 3H, ArOCH3), 3.89 (s, 3H, ArOCH3), 3.98 (s, 5%) as a purple solid, m.p. 275-279ºC; IR (CH2Cl2):
δ
2.93 (dd,
J
= 6.9, the column 5,6,8,13-tetrahydro-2,3-methylenedioxy-
-naphtho[2,3- ][3]benzazepine-8,13-dione 4d (5 mg,
J
7H
a
3H, ArOCH3), 5.78 (s, 1H, C=CH), 6.33 (br s, 1H, NH), νmax/cm−1, 3418, 1734, 1606; H-NMR (CDCl3)
6.63 (d, = 8.4 Hz, 1H, ArH), 6.85 (d, = 8.4 Hz, 1H, 2.98 (m, 2H, C-CH2), 3.83-3.90 (m, 2H, N-CH2), 5.99
ArH), 7.60 (td, = 1.2, 7.5 Hz, 1H, ArH), 7.71 (td, (s, 2H, OCH2O), 6.51 (br s, 1H, NH), 6.62 (s, 1H, ArH),
1.2, 7.5 Hz, 1H, ArH), 8.02 (dd, = 1.2, 7.5 Hz, 1H, 7.05 (s, 1H, ArH), 7.65 (td, = 1.3, 7.5 Hz, 1H, ArH),
ArH), 8.09 (dd, = 1.3, 7.5 Hz, 1H, ArH), 8.08 (dd, = 1.3,
= 1.2, 7.5 Hz, 1H, ArH); 13C-NMR 7.77 (td,
(CDCl3) 28.8, 43.7, 56.0, 60.8, 61.0, 100.7, 107.4, 123.9, 7.5 Hz, 1H, ArH), 8.21 (dd, = 1.3, 7.5 Hz, 1H, ArH);
124.3, 126.1, 126.2, 130.6, 131.8, 133.7, 134.6, 142.3, 13C-NMR (CDCl3)
33.8, 50.9, 100.1, 106.9, 107.4,
148.2, 141.9, 152.9, 181.8, 182.9; HRES-MS m/z calcd 111.9, 112.5, 125.0, 125.9, 129.2, 131.1, 132.9, 133.8,
δ 2.94-
1
J
J
J
J =
J
J
J
J
J
δ
J
δ
for [M+H]+ C21H22NO5: 368.1498, found: 368.1579.
134.6, 142.4, 144.9, 146.3, 180.1, 181.3; HRES-MS m/z
calcd for [M+H]+ C19H14NO4: 320.0923, found: 320.0984.
Cyclization of 3-bromo-2-(3,4-dimethoxypheneth- The second fraction gave 2-(2-(benzo[
ylamino)-1,4-naphthoquinone (3b) yl)ethylamino)naphthalene-1,4-dione (5d) (27.5 mg,
According to the general procedure; treatment of 3b 26%) as a red solid, m.p. 150-153ºC; IR (CH2Cl2): νmax
(0.16 g, 0.38 mmol) with Pd(OAc)2 (8.8 mg, 0.039 cm−1, 3391, 1732, 1609; 1H-NMR (CDCl3)
2.78 (t,
mmol), PPh3 (20 mg, 0.078 mmol) and K2CO3 (0.16 g, 7.0 Hz, 1H, C-CH2), 3.30 (q, = 7.0 Hz, 2H, N-CH2),
1.14 mmol) in toluene (4.5 mL) gave in the first fraction 5.66 (s, 1H, C=CH), 5.82 (s, 2H, OCH2O), 5.93 (br s,
of the column 5,6,8,13-tetrahydro-2,3-dimethoxy-7 1H, NH), 6.55-6.59 (m, 2H, ArH), 6.65 (d, = 7.8 Hz,
naphtho[2,3- ][3]benzazepine-8,13-dione 4b (11.5 mg, 1H, ArH), 7.49 (td, = 1.2, 7.5 Hz, 1H, ArH), 7.61 (td,
7.3%) as a purple viscous solid, IR (CH2Cl2): νmax/cm−1,
= 1.2, 7.5 Hz, 1H, ArH), 7.89 (dd, = 1.2, 7.5 Hz, 1H,
3426, 1734, 1606; 1H-NMR (CDCl3) = 1.2, 7.5 Hz, 1H, ArH); 13C-NMR
2.96-3.00 (m, 2H, ArH), 7.98 (dd,
C-CH2), 3.83-3.87 (m, 2H, N-CH2), 3.90 (s, 3H, ArOCH3), (CDCl3) 32.9, 42.7, 99.5, 99.9, 107.4, 108.0, 120.6,
3.91 (s, 3H, ArOCH3), 6.54 (br s, 1H, NH), 6.61 (s, 1H, 125.1, 125.2, 129.4, 130.5, 130.9, 132.5, 133.7, 145.5,
H-16), 7.15 (s, 1H, H-13), 7.63 (td, = 1.3, 7.6 Hz, 1H, 146.7, 146.9, 180.7, 181.9; HRES-MS m/z calcd for
ArH), 7.74 (td, = 1.3, 7.6 Hz, 1H, ArH), 8.07 (d,
[M+H]+ C19H16NO4: 322.1079, found: 322.1148.
7.6 Hz, 1H, ArH), 8.20 (d,
= 7.6 Hz, 1H, ArH); 13C-
NMR (CDCl3) 34.9, 51.8, 55.9, 56.0, 110.9, 113.3, Cyclization of 2-(3-(benzyloxy)-4-methoxyphe-
d][1,3]dioxol-5-
/
δ
J =
J
H-
J
a
J
J
J
δ
J
δ
J
J
J =
J
δ
116.3, 124.9, 125.9, 126.8, 130.2, 132.0, 133.9, 134.4, nethylamino)-3-bromo-1,4-naphthoquinone (3e)
134.7, 143.5, 146.7, 148.6, 182.3, 182.5; HRES-MS m/ According to the general procedure; treatment of 3e
z
calcd for [M+H]+ C20H18NO4: 336.1236, found: 336.1301. (0.15 g, 0.31 mmol) with Pd(OAc)2 (7 mg, 0.031 mmol),
The second fraction gave 2-(3,4-dimethoxyphenethyl- PPh3 (16 mg, 0.063 mmol) and K2CO3 (0.13 g, 0.91
amino)naphthalene-1,4-dione (5b) (36.8 mg, 28%) as a mmol) in toluene (3.7 mL) gave in the first fraction of
orange solid, m.p. 140-142ºC; IR (CH2Cl2): νmax/cm−1, the column 3-benzyloxy-5,6,8,13-tetrahydro-2-methoxy-
3427, 1733, 1605; 1H-NMR (CDCl3)
6.9 Hz, 2H, C-CH2), 3.33 (q,
3.77 (s, 3H, ArOCH3), 3.78 (s, 3H, ArOCH3), 5.68 (s, νmax/cm−1, 3429, 1735, 1635; H-NMR (CDCl3)
1H, C=CH), 5.91 (br s, 1H, NH), 6.64-6.75 (m, 3H, 2.92 (m, 2H, C-CH2), 3.79-3.82 (m, 2H, N-CH2), 3.91
ArH), 7.50 (td, = 1.2, 7.5 Hz, 1H, ArH), 7.61 (td, (s, 3H, ArOCH3), 5.76 (s, 2H, OCH2), 6.52 (br s, 1H,
1.2, 7.5 Hz, 1H, ArH), 7.90 (dd, = 1.2, 7.5 Hz, 1H, NH), 6.62 (s, 1H, ArH), 7.17 (s, 1H, ArH), 7.30-7.34
ArH), 7.96 (dd, = 7.5 Hz, 1H, ArH), 7.75 (t,
= 1.2, 7.5 Hz, 1H, ArH); 13C-NMR (m, 5H, ArH), 7.63 (t,
(CDCl3)
126.2, 130.3, 130.5, 131.9, 133.6, 134.7, 147.7, 148.0, (d,
δ
2.83 (dd,
J
= 7.2,
7H-naphtho[2,3-a][3]benzazepine-8,13-dione 4e (18 mg,
J
= 6.9 Hz, 2H, N-CH2), 14%) as a purple solid, m.p. 194-196ºC; IR (CH2Cl2):
1
δ
2.88-
J
J =
J
J
J
J
δ
33.9, 13.7, 55.9x2C, 100.9, 111.8, 120.6, 126.1, = 7.5 Hz, 1H, ArH), 8.06 (d,
J
= 7.5 Hz, 1H, ArH), 8.20
J
= 7.5 Hz, 1H, ArH); 13C-NMR (CDCl3)
δ
33.7,
149.2, 181.7, 182.9; HRES-MS m/z calcd for [M+H]+ 50.7, 55.2, 70.0, 112.2, 112.6, 115.9, 124.5, 124.9, 125.8,
C20H20NO4: 338.1392, found: 338.1456.
162.2*2, 126.8, 127.5x2C, 129.2, 130.9, 132.9, 133.3,
133.7, 136.1, 142.5, 146.4, 146.8, 181.3, 181.4; HRES-
Cyclization of 2-(2-(benzo[
amino)-3-bromo-1,4-naphthoquinone (3d)
According to the general procedure; treatment of 3d The second fraction gave 2-(3-(benzyloxy)-4-methoxy-
d
][1,3]dioxol-5-yl)ethyl- MS m/z calcd for [M+H]+ C26H22NO4: 412.1549, found:
412.1634.

Synthesis and Anticancer Activity of Naphthoazepines
773
phenethylamino)naphthalene-1,4-dione (5e) (30 mg, 490.1997.
23%) as a purple solid, m.p. 136-138ºC; IR (CH2Cl2):
1
νmax/cm−1, 3391, 1733, 1609; H-NMR (CDCl3)
δ
2.85 Cyclization of 3-bromo-2-(2,3,4-trimethoxyphe-
(dd,
J
= 6.9, 7.2 Hz, 1H, C-CH2), 33.4 (td,
J
= 6.6, 6.9 nethylamino)-5-methoxy-1,4-naphthoquinone (3g)
Hz, 1H, N-CH2), 3.87 (s, 3H, ArOCH3), 5.14 (s, 2H, O- According to the general procedure; treatment of 3g
CH2), 5.74 (s, 1H, C=CH), 5.91 (br s, 1H, NH), 6.74- (0.13 g, 0.27 mmol), Pd(OAc)2 (6.3 mg, 0.028 mmol),
6.78 (m, 2H, ArH), 6.85 (d,
7.28 (td, = 8.1, 1.2 Hz, 5H, ArH), 7.34 (td,
1.2 Hz, 1H, ArH), 7.71 (td, = 7.5, 1.2 Hz, 1H, ArH), 5,6,8,13-tetrahydro-2,3,4,9-tetramethoxy-7
8.00 (d, = 7.5 Hz, ArH), 8.10 (d,
ArH); 13C-NMR (CDCl3)
J
= 8.1 Hz, 1H, ArH), 7.25- PPh3 (15 mg, 0.056 mmol), K2CO3 (0.11 g, 0.82 mmol)
= 7.5, in toluene (3 mL) gave the first column fraction as
-naphtho
J
J
J
H
J
J = 7.5 Hz, 1H, [2,3-a][3]benzazepine-8,13-dione 4g (30 mg, 28%) as a
δ
33.7, 43.6, 53.4, 71.2, 100.9, viscous solid, IR (CH2Cl2): νmax/cm−1, 3330, 1668, 1607,
1
112.2, 114.7, 121.4, 126.4, 126.2, 127.3x2C, 127.9, 128.5 1580; H-NMR (CDCl3)
δ 3.07-3.10 (m, 2H, C-CH2),
x2C, 130.2, 130.5, 132.0, 133.6, 134.8, 137.0, 147.7, 3.79-3.82 (m, 2H, N-CH2), 3.84 (s, 3H, ArOCH3), 3.87
148.4, 148.8, 181.7, 182.9; HRES-MS m/z calcd for (s, 3H, ArOCH3), 3.92 (s, 3H, ArOCH3), 4.03 (s, 3H,
[M+H]+ C26H24NO4: 414.1705, found: 414.1787.
ArOCH3), 6.70 (br s, 1H, NH), 6.96 (s, 1H, ArH), 7.20
(d, = 8.5 Hz, 1H, ArH), 7.69 (d, = 7.7, 8.2 Hz, 1H,
Cyclization of 2-(3,4-bis(benzyloxy)phenethyl- ArH), 7.89 (d,
= 7.7 Hz, 1H, ArH); 13C-NMR (CDCl3)
amino)-3-bromo-1,4-naphthoquinone (3f) 25.3, 51.8, 56.0, 56.5, 60.9, 61.5, 111.4, 112.2, 115.6,
J
J
J
δ
According the general procedure; treatment of 3f 117.9, 119.7, 127.9, 128.7, 136.0, 136.4, 141.5, 144.8,
(0.16 g, 0.28 mmol), Pd(OAc)2 (7 mg, 0.028 mmol), PPh3 149.6, 150.9, 159.6, 18.05, 181.7; HRES-MS m/z calcd
(15 mg, 0.057 mmol), K2CO3 (0.12 g, 0.84 mmol) in for [M+H]+ C22H22NO6: 396.1447, found: 396.1398.
toluene (3 mL) gave the first fraction of the column as The second fraction gave 2-(2,3,4-trimethoxypheneth-
2,3-dibenzyloxy-5,6,8,13-tetrahydro-7
[3]benzazepine-8,13-dione 4f (34 mg, 25%) as a purple 35%) as a red solid, m.p. 130-132oC; IR (CH2Cl2): νmax
solid, m.p. 139-142oC; IR (CH2Cl2): νmax/cm−1, 3343, 1667, cm−1, 3355, 1670, 1609, 1581; 1H-NMR (CDCl3)
2.91
1598, 1567; 1H-NMR (CDCl3)
2.93 (t, = 4.5 Hz, 2H, (t, = 6.85 Hz, 2H, C-CH2), 3.37 (q, = 6.4 Hz, 2H, N-
C-CH2), 3.80 (q, = 4.3 Hz, 2H, N-CH2), 5.20 (s, 4H, CH2), 3.85 (S, 3H, ArOCH3), 3.88 (S, 3H, ArOCH3),
O-CH2), 6.71 (s, 1H, ArH), 7.33-7.41 (m, 7H, ArH), 3.96 (S, 3H, ArOCH3), 3.99 (S, 3H, ArOCH3), 5.73 (s,
7.47-7.54 (m, 4H, ArH), 7.64 (td, = 1.2, 7.5 Hz, 1H, 1H, ArH), 6.33 (br s, 1H, NH), 6.62 (d, = 8.5 Hz, 1H,
ArH), 7.76 (td, = 1.2, 7.5 Hz, 1H, ArH), 8.08 (dd, ArH), 6.84 (d, = 8.5 Hz, 1H, ArH), 7.17 (dd, = 0.8,
0.9, 7.8 Hz, 1H, ArH), 8.23 (dd, = 1.2, 7.8 Hz, 1H, 8.5 Hz, 1H, ArH), 7.65 (dd, = 7.7, 8.3 Hz, 1H, ArH),
ArH); 13C-NMR (CDCl3) = 1.0, 7.6 Hz, 1H, ArH); 13C-NMR (CDCl3)
34.8, 51.6, 71.3, 71.5, 114.5, 7.78 (dd,
114.6, 119.9, 125.8, 125.8, 126.8, 127.3, 127.4, 127.6, 28.9, 43.4, 56.0, 56.4, 60.9, 61.0, 99.2, 107.4, 115.8,
H
-naphtho[2,3-
a]
ylamino)-5-methoxynaphthalene-1,4-dione (5g) (38 mg,
/
δ
δ
J
J
J
J
J
J
J
J
=
J
J
J
J
δ
J
δ
127.6, 127.7, 127.8, 128.3, 128.4, 130.2, 131.9, 133.2, 118.3, 119.0, 123.8, 124.3, 135.9, 136.1, 142.3, 149.0,
133.9, 134.7, 135.2, 137.3, 137.5, 143.4, 146.9, 148.6; 151.9, 152.9, 160.0, 180.1, 182.4; HRES-MS m/z calcd
HRES-MS m/z calcd for [M+H]+ C32H26NO4: 488.1862, for [M+H]+ C22H24NO6: 398.1603, found: 398.1540.
found: 488.1819.
The second fraction gave 2-(3,4-bis(benzyloxy)phene- Cyclization of 3-bromo-2-(3,4-dimethoxyphene-
thylamino)naphthalene-1,4-dione (5f) (32 mg, 23%) as thylamino)-5-methoxy-1,4-naphthoquinone (3h)
a red solid, m.p. 125-128oC; IR (CH2Cl2): νmax/cm−1, According to the general procedure; treatment of 3h
3353, 1676, 1606, 1569, 1510; 1H-NMR (CDCl3)
(t, = 7.0 Hz, 2H, C-CH2), 3.37 (q,
CH2), 5.16 (s, 2H, CH2Ar), 5.17 (s, 2H, CH2Ar), 5.17 (s, in toluene (3 mL) gave the first column fraction as 5,
1H, C=CH), 5.95 (br s, 1H, NH), 6.75 (dd, = 1.9, 8.1 6,8,13-tetrahydro-2,3,9-trimethoxy-7 -naphtho[2,3-
Hz, 1H, ArH), 6.81 (d, = 1.9 Hz, 1H, ArH), 6.92 (d, [3]benzazepine-8,13-dione 4h (28 mg, 34%) as a pur-
= 8.1 Hz, 1H, ArH), 7.32-7.48 (m, 10H, ArH), 7.62 (td, ple solid, m.p. 137-139oC; IR (CH2Cl2): νmax/cm−1, 3328,
= 1.2, 7.5 Hz, 1H, ArH), 7.74 (td, 2.97 (t,
= 1.2, 7.5 Hz, 1H, 1668, 1607, 1574, 1514; 1H-NMR (CDCl3)
ArH), 8.04 (d, = 7.5 Hz, 1H, ArH), 8.13 (d, = 7.5 Hz, 4.6 Hz, 2H, C-CH2), 3.85 (q, = 4.1 Hz, 2H, N-CH2),
1H, ArH); 13C-NMR (CDCl3)
33.8, 43.6, 71.4, 71.5, 3.91 (s, 3H, ArOCH3), 3.92 (s, 3H, ArOCH3), 4.05 (s, 3H,
100.9, 115.5, 115.7, 121.6, 126.2, 126.3, 127.4, 127.6, ArOCH3), 6.61 (s, 1H, ArH), 6.70 (br s, 1H, NH), 7.19
127.8, 127.9, 128.5, 130.5, 131.1, 132.0, 133.6, 134.8, (s, 1H, ArH), 7.21 (dd, = 0.8, 8.1 Hz, 1H, ArH), 7.70
137.2, 137.3, 147.7, 148.1, 149.2, 181.7, 183.0; HRES- (t, = 7.7, 8.4 Hz, 1H, ArH), 7.90 (dd, = 1.0, 7.7 Hz,
MS m/z calcd for [M+H]+ C32H28NO4: 490.2018, found: 1H, ArH); 13C-NMR (CDCl3)
29.7, 51.7, 55.9, 56.0,
δ
2.87 (0.10 g, 0.22 mmol), Pd(OAc)2 (5.2 mg, 0.023 mmol),
J
J = 6.5 Hz, 2H, N- PPh3 (12 mg, 0.046 mmol), K2CO3 (93 mg, 0.68 mmol)
J
H
a]
J
J
J
J
δ
J =
J
J
J
δ
J
J
J
δ

774
W. Phutdhawong et al.
56.5, 110.9, 111.6, 115.6, 116.1, 118.0, 119.6, 124.8, Purification by flash chromatography on silica gel
134.2, 135.9, 136.5, 144.5, 146.7, 148.4, 159.6, 180.7, (hexane-EtOAc 4:1) gave 6f (32 mg, 82%) as a dark
181.9; HRES-MS m/z calcd for [M+H]+ C21H20NO5: purple solid, m.p. decomposed >289oC; 1H-NMR (CDCl3)
366.1341, found: 366.1328.
The second fraction gave 2-(3,4-dimethoxyphenethyl- ArH), 6.97 (s, 1H, ArH), 7.69 (td,
amino)-5-methoxynaphthalene-1,4-dione (5h) (35 mg, ArH), 7.79 (td, = 1.2, 7.5 Hz, 1H, ArH), 8.06 (d,
42%) as a red solid; m.p. 132-134oC; IR (CH2Cl2): νmax = 7.8 Hz, 1H, ArH); 13C-
7.5 Hz, 1H, ArH), 8.10 (d,
cm−1, 3358, 1669, 1609, 1581, 1514; 1H-NMR (CDCl3)
NMR (CDCl3) 34.5, 51.6, 113.2, 119.4, 124.0, 126.1,
2.89 (t, = 6.9 Hz, 2H, C-CH2), 3.38 (q, = 6.5 Hz, 2H, 127.0, 128.7, 130.2, 132.2, 133.9, 134.4, 134.9, 141.9,
δ
2.88 (t, 2H, C-CH2), 3.75 (t, 2H, N-CH2), 6.59 (s, 1H,
J
= 1.2, 7.5 Hz, 1H,
J
J =
/
J
δ
δ
J
J
N-CH2), 3.84 (s, 3H, ArOCH3), 3.85 (s, 3H, ArOCH3), 143.9, 144.4, 181.9, 183.4; HR-ESIMS m/z calcd. for
3.95 (s, 3H, ArOCH3), 5.69 (s, 1H, C=CH), 6.09 (br s, [M+H]+ C18H14NO4: 308.0923, found: 308.0915.
1H, NH), 6.70-6.76 (m, 2H, ArH), 6.80 (d,
1H, ArH), 7.14 (d, = 0.9, 8.3 Hz, 1H, ArH), 7.62 (td,
= 7.8, 8.3 Hz, 1H, ArH), 7.74 (dd, = 0.9, 8.3 Hz, 1H,
ArH); 13C-NMR (CDCl3)
99.3, 111.5, 111.7, 115.8, 118.1, 118.9, 120.7, 130.3,
J = 8.1 Hz,
J
Pharmacology
In vitro evaluation of cytotoxic activity using
J
J
δ
33.9, 43.6, 55.9x2C, 56.4, MTT assay
All the synthesized compounds were tested at the
135.9, 136.0, 147.9, 148.6, 149.2, 160.0, 179.9, 182.4; Department of Microbiology, Silpakorn University,
HRES-MS m/z calcd for [M+H]+ C21H22NO5: 368.1498, Thailand. Four cell lines were used for the evaluation-
found: 368.1484.
human breast carcinoma cell line (MCF7), human
cervix carcinoma cell line (HeLa), HepG2 and human
keratinocyte cell line (HaCaT). Cytotoxicity studies
were performed on a 96-well plate. All cell lines were
5,6,8,13-tetrahydro-3-hydroxy-2-methoxy-7H-na-
phtho[2,3-a][3]benzazepine-8,13-dione (6e)
Palladium on activated carbon (7.1 mg, 10% w/w) was mechanically scraped and plated 2
added to a solution of 4e (71 mg, 0.14 mmol) in MeOH well plate containing 100 L of Dulbecco's modified
×
105/well on a 96-
µ
(3 mL) on activated carbon (7.1 mg, 10% w/w) and the Eagle's medium (DMEM) with 10% fetal bovine serum
resulting suspension was stirred under a hydrogen (FBS) and incubated at 37oC and 5% CO2, overnight. All
atmosphere for 12 h (a balloon of hydrogen gas was compounds to be tested were dissolved in
N,N-dimethyl-
equipped to the reaction flask). The mixture was formamide (DMF) to give the stock solution. The DMF
filtered and the solvent was removed under reduced concentrations in all assays did not exceed 0.1%.
pressure. Purification by flash chromatography on Twenty-four hours after seeding, 100
silica gel (hexane-EtOAc 4:1) gave 6e (31 mg, 69%) as or test compound (at the concentration of 12.5, 25, 50,
a dark purple solid, m.p. 211-213oC; IR (CH2Cl2): νmax
100, 200 g/mL) was added, and the plates were incu-
cm−1, 3339, 1667, 1598, 1566, 1511; 1H-NMR (CDCl3)
bated for 24 h. Cells were washed once before the 50
2.94 (t, = 4.5 Hz, 1H, C-CH2), 3.83 (q, = 4.5 Hz, 2H, L FBS-free medium containing 5 mg/mL MTT was
µL new medium
/
µ
δ
J
J
µ
N-CH2), 3.92 (s, 3H, OCH3), 5.74 (br s, 1H, OH), 6.55 added. After 4 h of inoculation at 37oC, the medium
(br s, 1H, NH), 6.71 (s, 1H, ArH), 7.14 (s, 1H, ArH), was discarded and the formazan blue, which formed
7.28 (s, 1H, ArH), 7.64 (t,
(t, = 7.5 Hz, 1H, ArH), 8.07 (d,
8.21 (d,
= 7.6 Hz, 1H, ArH); 13C-NMR (CDCl3)
J
= 7.5 Hz, 1H, ArH), 7.76 in the cells, was dissolved in 50
= 7.6 Hz, 1H, ArH), density was measured at 540 nm. Moreover, the con-
34.5, centration required for reducing the absorbance by 50%
µL DMSO. The optical
J
J
J
δ
51.8, 56.2, 113.8, 115.7, 124.3, 125.5, 125.9, 126.8, 130.2, (IC50) compared to the control cells was determined.
132.0, 133.9, 134.7, 135.2, 143.5, 144.5, 145.4, 182.3,
182.5; HR-ESIMS m/z calcd. for [M+H]+ C19H16NO4:
RESULTS AND DISCUSSION
322.1079, found: 322.1074.
The construction of the 7H-naphtho[2,3-a][3]-benza-
5,6,8,13-tetrahydro-2,3-dihydroxy-7
H-naphtho[2,3-
zepine-8,13-diones skeleton was based on a palladium-
catalyzed intramolecular cyclization of 2-bromo-3-ethyl-
a][3]benzazepine-8,13-dione (6f)
Palladium on activated carbon (5 mg, 10% w/w) was aminophenol-1,4-naphthoquinones as the key step. The
added to a solution of 4f (50 mg, 0.12 mmol) in MeOH starting materials, 2,3-dibromo-1,4-naphthoquinones
(3 mL) on activated carbon (5 mg, 10% w/w) and the 1a-b), were prepared according to a previous report
(
resulting suspension was stirred under a hydrogen (Miguel del Corral et al., 2005). Nucleophilic substitu-
atmosphere for 8 h (a balloon of hydrogen gas was tions of 2,3-dibromo-1,4-naphthoquinones (1a) with
equipped to the reaction flask). The mixture was filtered various phenethylamines (2a-f) (Nimgirawath et al.,
and the solvent was removed under reduced pressure. 2009) in dichloromethane-ethanol at room tempera-

Synthesis and Anticancer Activity of Naphthoazepines
775
Scheme 1. Synthesis of aminonaphthoquinones (3a-h).
ture afforded the corresponding aminonaphthoquinones del Corral et al., 2006a). This was probably due to the
3a-f) (Scheme 1) in moderate yields (36-75%). In the flexibility of the phenethylamine bond which led to
case of 2,3-dibromo-5-methoxy-1,4-naphthoquinone conformation unfavorable for the formation of the
1b), the substitutions were probably at C-3 of the 5- cyclized/reduced products, as 3c did not give any
(
(
methoxynaphthoquinones. The structures of 3g-h could cyclized or reduced products, only very complex reac-
1
not be confirmed by H- and 13C-NMR. However, the tion products were obtained. Cyclization of 5a was
regioselective addition of amines at C-3 of juglone had achieved in a separate reaction with Pd(OAc)2 in AcOH
been reported previously (Chaker et al., 1994; Knölker to afford the seven-membered ring heterocyclic naph-
and O'Sullivan, 1994).
thoquinone (4a) in a 15% yield. The structures of the
1
The intramolecular cyclization of (3a-h) using a pal- cyclized products (4a-h) were supported by the H-
ladium(0)-catalyzed reaction was investigated. Several NMR which indicated the absence of the ortho-aroma-
standard conditions for aryl coupling to vinyl bromide tic proton of the phenethylamines. The 1H-NMR of the
using palladium(II) acetate in the presence of triphen- reduced products (5a-h) showed the presence of the
ylphosphine as a catalyst were applied. However, de- singlet proton at around
δ 5.5 ppm of the H-2 naphth-
composition products or recovered starting materials oquinone. The HMBC correlation of H-8/C-1 was more
were obtained. Substantial optimization to 10 mol% intense than the HMBC correlation of H-8/C-4 which
Pd(OAc)2 in the presence of 20 mol% of triphenylphos- confirmed the structure of
phine and 3 equiv. of K2CO3 in toluene at 120oC for 24
In additions, attempts to improve the yield by in-
h in a pressured tube afforded the corresponding creasing the mol% of Pd(OAc)2 or by using Pd(OAc)2 in
desired azepine-fused naphthoquinones , although in the presence of cupric acetate to reoxidize the Pd(0) to
relatively low yields and also the production of the Pd(II) did not give the expected cyclized products, only
reduced compounds (Scheme 2, Table I). In contrast the reduced products were obtained. Increasing the
5.
4
5
to the preparation of the fused five-membered hetero- reaction time yielded more reduced products. Thus,
cyclic ring on the quinone moiety, the application of a when the reaction was carried out at higher tempera-
palladium-catalyzed reaction presented the cyclized tures using mesitylene (bp. 163-175oC) as a solvent,
products in good yields (Van and Kimpe, 2003; Miguel much decomposition was observed.
Scheme 2. Palladium-catalyzed oxidative cyclization.

776
W. Phutdhawong et al.
Table I. Palladium-catalyzed oxidative cyclization to benzazepinonaphthiquinones
Product (% )
Entry
Substrate
R1
R2
R3
R4
4
5
1
2
3
4
5
6
7
8
3a
3b
3c
3d
3e
3f
H
H
OCH3
H
OCH3
OCH3
OCH3
OCH3
OCH3
H
18
31
11.5
−
28
−
H
H
H
H
-OCH2O-
5
26
23
23
35
42
H
H
OCH2Ph
OCH2Ph
OCH3
OCH3
OCH2Ph
OCH3
14
25
28
34
H
H
3g
3h
OCH3
OCH3
OCH3
H
OCH3
OCH3
Table II. Cytotoxicity data (IC50 in
derivatives 3-6
µ
g/mL) of 1,4-NQ
Compound
MCF7
HeLa
HepG2
HaCaT
3a
200.0
95.0
122.0
22.0
100.0
30.0
48.0
264.0
90.0
74.0
143.0
26.0
60.0
24.0
30.0
NT
60.0
59.0
100.0
41.0
48.0
78.0
28.0
290.0
106.0
66.0
76.0
61.0
56.0
42.0
48.0
NT
>50.0
33.0
34.0
24.0
5.8
21.0
66.0
3b
3f
48.0
3g
104.0
89.0
3h
Scheme 3. Debenzylation using catalytic hydrogenation.
4a
17.0
36.0
12.0
3.5
102.0
99.0
4b
4f
116.0
107.0
130.0
122.0
95.0
In an attempt to study the importance of the
hydroxyl group for the cytotoxicity, removal of the
methyl group from the phenolic group was attempted
by refluxing 3a and 3g in pyridine-hydrochloride but
only starting materials were recovered. However,
debenzylation of 4e and 4f was achieved by catalytic
hydrogenation to give 6e and 6f in 69% and 82%,
respectively.
4g
4h
3.0
5f
>50.0
25.0
31.0
18.0
>50.0
2.7
5g
5h
110.0
109.0
145.0
NT
6e
6f
Actinomycin D
Evaluation of the cytotoxicity of the synthesized
compounds was performed on different cell lines using
MTT colorimetric assay. DMF was used as a solvent
NT: not tested
control. The IC50 (µg/mL) values were compared with synthesized via an intramolecular palladium-catalyz-
the anticancer drug actinomycin D and the results are ed cyclization of aminonaphthoquinones (3a-g) and
summarized in Table II. Compounds 4g and 4h showed evaluated for their anticancer activities. Among the
marked anticancer activities against HepG2 cell line tested compounds, 4g and 4h were the most effective
with less cytotoxicity against the normal cell line against HepG2, showing IC50 values of 3.5 and 3.0 µg/
(HaCaT). The presence of a methoxy substituent at C- mL, respectively. Although these compounds showed
5 position of the 1,4-naphthoquinone ring (4g-h) caused fewer cytotoxic effects in comparison with the anti-
an improvement in activity in comparison with the cancer drugs, the series of benzazepinonaphthoquino-
unsubstituted quinones (4a-b). Futhermore, the sub- nes derivatives may be considered as structure lead
stituents on the benzene ring of the benzazepine also compounds for further development of anticancer
affected the activity. Compound 4f bearing 3,4-di- agents.
benzyloxy substituents possessed moderated activity
against HepG2 cell line and low activity against the
two tumor cell lines (MCF7, HeLa) and the normal
cell line (HaCaT). However, replacement of the 3,4-
ACKNOWLEDGEMENTS
We gratefully acknowledge support from the Fac-
dibenzyloxy group with a 3,4-dimethoxy group and ulty of Science, Silpakorn University and the Depart-
hydroxyl group resulted in much reduced activity.
In conclusion, azepinonaphthoquinones (4a
ment of Chemistry, Silpakorn University for a schol-
) were arship (to G.E). The Human keratinocyte cell line
-g

Synthesis and Anticancer Activity of Naphthoazepines
777
Gualberto, S. A., Cuevas, C., and San Feliciano, A., New
cytotoxic furoquinones obtained from terpenyl-1,4-na-
phthoquinones and 1,4-anthracenediones. Bioorg. Med.
Chem., 14, 7231-7240 (2006b).
(HaCaT) was kindly provided by Professor Dr. N.E.
Fusenig, Division of Differentiation and Carcinogenesis,
German Cancer Research Center (DKFZ), Heidelberg,
Germany.
Nimgirawath, S., Udomputtimekakul, P., Taechowisan, T.,
Wanbanjob, A., and Shen, Y., First total syntheses of ( )-
isopiline, ( )-preocoteine, ( )-oureguattidine and ( )-3-
methoxynordomesticine and the biological activities of ( )-
3-methoxynordomesticine. Chem Pharm Bull. (Tokyo), 57,
368-376 (2009).
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