6818
L. Matesic et al. / Tetrahedron 68 (2012) 6810e6819
(CDCl3, 500 MHz):
d
4.36 (t, J¼6.5 Hz, 2H), 4.63 (t, J¼6.5 Hz, 2H),
1H), 7.50 (t, J¼7.5 Hz, 1H), 7.56 (t, J¼7.5 Hz, 1H), 7.74 (d, J¼8.0 Hz,
1H), 7.85 (d, J¼9.0 Hz, 1H), 8.17 (d, J¼8.5 Hz, 1H), 8.63 (d, J¼9.0 Hz,
5.27 (s, 2H), 7.08 (t, J¼7.0 Hz, 1H), 7.25 (d, J¼7.5H, 1H), 7.50 (t,
J¼8.0 Hz,1H), 7.56 (t, J¼8.0 Hz,1H), 7.72 (d, J¼8.0 Hz, 2H), 7.79e7.84
1H). 13C NMR (CDCl3, 126 MHz):
d
44.5, 66.1,y 119.1, 121.6, 123.3,
(m, 3H). 13C NMR (CDCl3, 126 MHz):
d
40.7, 65.9,y 103.2, 117.4, 120.0,
124.1, 125.1, 125.3, 125.5, 126.1, 127.3, 129.2, 129.3, 129.4, 129.8,
130.2, 134.4, 141.9,y174.3. LREI-MS: m/z (%): 329 (44) [Mþ], 300
(100), 256 (31), 229 (28), 201 (18), 128 (33), 114 (32), 100 (28).
HRESI-MS: m/z calcd for C21H16NO3 [MþH]þ: 330.1130; found
330.1081.
122.3, 122.4, 123.4, 123.5, 124.3, 124.5, 125.2, 126.4, 127.3, 128.7,
128.8, 130.3, 133.0, 139.3, 183.2. LREI-MS: m/z (%): 329 (33) [Mþ],
300 (100), 256 (33), 229 (30), 201 (57), 128 (30), 114 (33). HRESI-
MS: m/z calcd for C21H16NO3 [Mþ]: 330.1130; found 330.1117.
4.2.29. 7H-Benzo[j]pyrrolo[3,2,1-de]phenanthridine-4,5-dione
(36). The cyclised ketal 35 (1.10 g, 3.34 mmol) was dissolved in 6 M
HCl/THF (1:1, 35 mL) and heated at reflux for 5 h. Upon cooling, H2O
(200 mL) was added, the solution filtered and washed with more
H2O to yield 36 as a fine dark red powder (641 mg, 67%), mp
4.2.33. 7H-Benzo[l]pyrrolo[3,2,1-de]phenanthridine-4,5-dione
(40). The compound was prepared according to the method for 36
using the cyclised ketal 39 (420 mg, 1.28 mmol) in 6 M HCl/THF
(1:1, 13.4 mL) as starting materials to yield 40 as a fine dark red
powder (330 mg, 90%), mp 205e207 ꢀC. 1H NMR (CDCl3, 500 MHz):
251e253 ꢀC. 1H NMR (CDCl3, 500 MHz):
d
5.44 (s, 2H), 7.14 (t,
d
5.15 (s, 2H), 7.18 (t, J¼8.0 Hz, 1H), 7.24 (d, J¼8.0 Hz, 1H), 7.48 (d,
J¼7.5 Hz, 1H), 7.45 (d, J¼7.5 Hz, 1H), 7.62 (t, J¼7.0 Hz, 1H), 7.66 (t,
J¼7.5 Hz, 1H), 7.95 (d, J¼8.5 Hz, 1H), 8.01 (t, J¼7.5 Hz, 2H), 8.16 (d,
J¼9.0 Hz, 1H), 8.25 (d, J¼8.0 Hz, 1H). 13C NMR (CDCl3, 126 MHz):
J¼7.5 Hz, 1H), 7.55 (t, J¼8.5 Hz, 1H), 7.60 (td, J¼1.0, 8.5 Hz, 1H), 7.80
(d, J¼8.5 Hz, 1H), 7.89 (d, J¼8.0 Hz, 1H), 8.37 (d, J¼8.0 Hz, 1H), 8.55
(d, J¼8.5 Hz, 1H). 13C NMR (CDCl3, 126 MHz):
d 44.3, 117.2, 120.2,
d
40.8, 115.7, 118.7, 119.6, 122.4, 123.4, 124.4, 124.7, 127.0, 127.8,
123.6, 123.9, 124.2, 124.6, 124.7, 126.3, 127.6, 129.2, 129.8, 129.9,
130.8, 134.2, 135.6, 149.2, 158.8, 183.1. LREI-MS: m/z (%): 285 (48)
[Mþ], 256 (100), 228 (35), 201 (26), 128 (13), 114 (39), 100 (48).
HRESI-MS: m/z calcd for C19H12NO2 [MþH]þ: 286.0868; found
286.0860.
129.2, 129.9, 130.2, 130.8, 133.3, 134.2, 146.5, 157.8, 182.9. LREI-MS:
m/z (%): 285 (55) [Mþ], 256 (100), 229 (38), 201 (32), 128 (23), 114
(40), 100 (43). HRESI-MS: m/z calcd for C19H12NO2 [MþH]þ:
286.0868; found 286.0829.
4.2.30. 7-Iodo-1-(naphthalen-2-ylmethyl)-1H-indole-2,3-dione
(37). The compound was prepared according to the method for 13
using 32 (2.50 g, 9.16 mmol), NaH (307 mg, 12.8 mmol), KI (304 mg,
1.83 mmol) and 2-(bromomethyl)naphthalene (3.03 g, 13.7 mmol)
as starting materials. The resulting solid was purified by flash
chromatography (100% CHCl3) to yield 37 as red/brown crystals
4.2.34. 2-Bromo-7H-benzo[l]pyrrolo[3,2,1-de]phenanthridine-4,5-di-
one (41). According to the bromination method of Zysman-
Colman et al.,35 the cyclised phenanthridine 40 (100 mg,
351
m
mol) was dissolved in anhydrous CH3CN (1 mL) at 0 ꢀC.
NBS (62.5 mg, 351 mol) in anhydrous CH3CN (1 mL) was added
and the reaction mixture was warmed to rt and stirred for 18 h.
DCM (30 mL) was added and the solution was extracted with
H2O (3ꢃ20 mL). The organic extract was dried over MgSO4, fil-
tered and evaporated. The resulting solid was purified using
flash chromatography (100% CHCl3) to yield 41 as a fine dark red
powder (49.2 mg, 39%), mp 197e199 ꢀC. 1H NMR (CDCl3,
(1.37 g, 36%), mp 154e155 ꢀC. 1H NMR (CDCl3, 500 MHz):
d 5.64 (s,
2H), 6.88 (t, J¼7.5 Hz, 1H), 7.38 (d, J¼7.5 Hz, 1H), 7.46 (dd, J¼3.0,
6.0 Hz, 2H), 7.61 (s, 1H), 7.68 (d, J¼6.5 Hz, 1H), 7.75 (dd, J¼3.0,
5.5 Hz, 1H), 7.81e7.85 (m, 2H), 7.94 (d, J¼8.0 Hz, 1H). 13C NMR
(CDCl3, 126 MHz):
d 43.8, 73.7, 120.8, 124.4, 124.9, 125.5, 125.7,
126.0, 126.4, 127.7, 127.8, 128.7, 132.7, 133.3,y 150.9, 151.1, 159.2,
182.4. LREI-MS: m/z (%): 413 (56) [Mþ], 272 (85) [M-CH2C10H7], 141
(100), 115 (47). HRESI-MS: m/z calcd for C19H13INO2 [MþH]þ:
413.9991; found 413.9950.
500 MHz):
d
5.09 (s, 2H), 7.20 (d, J¼8.0 Hz, 1H), 7.47e7.57 (m,
2H), 7.63 (app. br s, 1H), 7.81 (d, J¼8.0 Hz, 1H), 7.87 (d, J¼7.0 Hz,
1H), 8.30e8.35 (m, 1H), 8.41 (br s, 1H). 13C NMR (CDCl3,
126 MHz):
d 44.2, 116.6, 118.1, 122.0, 122.7, 124.0, 124.6, 126.1,
126.5, 128.1, 129.4, 129.6, 130.7, 134.1, 135.6, 137.5, 147.9, 157.9,
4.2.31. 70-Iodo-10-(naphthalen-2-ylmethyl)spiro[[1,3]-dioxolane-
2,30-indolin]-20-one (38). The compound was prepared according to
the method for 34 using the isatin 37 (1.10 g, 2.66 mmol), ethylene
glycol (4.95 g, 4.45 mL, 79.8 mmol) and PTSA (110 mg, 10% of
starting material weight) as starting materials. The resulting solid
was purified by flash chromatography (100% DCM) to yield 38 as
a beige powder (1.12 g, 92%), mp 156e158 ꢀC. 1H NMR (CDCl3,
181.7. LREI-MS: m/z (%): 363/365 (24) [Mþ] 79Br/81Br, 334/336
(38), 256 (53), 227 (61), 200 (35), 100 (65). HRESI-MS: m/z calcd
79
for C19
H
BrNO2 [MþH]þ: 363.9973; found 363.9991.
11
4.3. Cytotoxicity testing
500 MHz):
d
4.36e4.39 (m, 2H), 4.62e4.64 (m, 2H), 5.51 (s, 2H),
Human U937 histiocytic lymphoma cells were obtained from the
American Type Culture Collection (ATCC, VA, USA). Cells were rou-
tinely maintained in RPMI-1640 medium, containing 2 mM L-glu-
6.82 (t, J¼8.0 Hz, 1H), 7.35 (dd, J¼1.5, 8.5 Hz, 1H), 7.41 (dd, J¼1.0,
7.0 Hz, 1H), 7.43e7.45 (m, 2H), 7.57 (s, 1H), 7.71 (dd, J¼1.0, 8.5 Hz,
1H), 7.75e7.77 (m, 1H), 7.80e7.82 (m, 2H). 13C NMR (CDCl3,
tamine, 5.6% (2 g/L) sodium bicarbonate and 5% foetal calf serum (at
37 ꢀC, 95% humidified atmosphere and 5% CO2). Cytotoxicity of the
isatin derivatives was determined using the CellTiter 96Ò AQueous
One Solution Cell Proliferation Assay (MTS assay) (Promega Co.,
Madison, WI, USA) as described previously.1c The concentration re-
quired to inhibit 50% of the metabolic activity of the cell population
(IC50) was calculated from sigmoidal doseeresponse curves using
GraphPad Prism 5.00 (GraphPad Software Inc., San Diego, CA, USA)
from at least two independent experiments performed in triplicate.
126 MHz):
d
43.7, 66.3,y 72.6, 101.1, 124.5, 124.7, 124.9, 125.2, 125.7,
126.1,127.4,127.6, 127.9, 128.5, 132.6,133.4,134.1,144.4,144.5,174.5.
LREI-MS: m/z (%): 457 (23) [Mþ], 316 (100) [MꢁCH2C10H7], 272 (45)
[MꢁCH2C10H7e(CH2)2O], 141 (37), 115 (35). HRESI-MS: m/z calcd
for C21H17INO3 [MþH]þ: 458.0253; found 458.0215.
4.2.32. Spiro[benzo[l]pyrrolo[3,2,1-de]phenanthridine-4,20-[1,3]diox-
olan]-5(7H)-one (39). The compound was prepared according to
the method for 35 using the ketal 38 (1.00 g, 2.19 mmol), Pd(OAc)2
(49.2 mg, 219
mmol), TBAB (777 mg, 2.41 mmol) and NaOAc
(902 mg, 11.0 mmol) as starting materials. The resulting solid was
purified using flash chromatography (100% CHCl3) to yield 39 as
a beige powder (485 mg, 67%), mp 161e163 ꢀC. 1H NMR (CDCl3,
Acknowledgements
We thank the University of Wollongong for financial support
through the Centre for Medicinal Chemistry (CMC), a University of
Wollongong Small Grant and an Australian Postgraduate Award to L.M.
500 MHz):
d
4.36 (t, J¼6.5 Hz, 2H), 4.61 (t, J¼6.5 Hz, 2H), 5.05 (s,
2H), 7.14 (t, J¼8.0 Hz, 1H), 7.21 (d, J¼8.5 Hz, 1H), 7.30 (d, J¼7.5 Hz,