A. Beauchard et al. / Bioorg. Med. Chem. 17 (2009) 6257–6263
6261
0
0
ture was then heated to 80 °C for 15 min, allowed to cool to 70 °C,
and cooled on ice. The solution was then poured into ice, and was
extracted with ethyl acetate and washed with water. The organic
5.1.4.4. (2 Z)-5 -Bromo-6-nitroindirubin (18). Yield: 55% . mp
1
>260 °C. H NMR (400 MHz, DMSO-d
11.29 (s, N H), 8.85 (d, 1H, J = 8.8 Hz, H-4), 7.94 (d, 1H,
J = 10.4 Hz, H-6 ), 7.80 (s, 1H, H-7), 7.76 (d, 1H, J = 10.4 Hz, H-7 ),
7.60 (s, 1H, H-4 ), 7.42 (d, 1H, J = 8.8 Hz, H-5). IR 3296, 1683,
1607, 1460, 1119, 81 cm . HRMS (EI) [M] (C16
384.96982, found 384.9687.
6
) d ppm 11.48 (s, NH),
0
0
0
layer was dried (MgSO
4
) and the filtrate was concentrated under
0
reduced pressure. The crude residue were recrystallized from
1
ꢁ1
+Å
79
water. Yield : 65%. mp = 195–200 °C. H NMR (400 MHz, DMSO-
8
H N
3
O
4
Br): calcd
6
d ) d ppm 8.19 (d, 1H, J = 8.0 Hz, H-4), 7.92 (d, 1H, J = 7.2 Hz, H-
13
6
), 7.44 (t, 1H, J = 7.2 and 8.0 Hz, H-5).
C NMR (100 MHz,
0
1
6
DMSO-d ) d ppm 183.57, 159.45, 149.30, 140.27, 124.03, 123.43,
5.1.4.5. (2 Z)-6-Aminoindirubin (22). Yield: 57%. Mp >260 °C. H
NMR (400 MHz, DMSO-d
NH), 8.57 (d, 1H, J = 8.4 Hz, 4-H), 7.58 (d, 1H, J = 7.6 Hz, H arom),
,47 (t, 1H, J = 7.6 Hz, H arom), 7,29 (d, 1H, J = 8.4 Hz, 5-H), 6,92
0
1
(
19.98, 104.53. IR = 3179, 1737, 1613, 1322, 1130, 757. HRMS
6
) d ppm 10.54 (s, 1H, N H), 10.43 (s, 1H,
EI) [M]+ (C
Å
H NO
4 2
79
Br) calcd 224.94254, found 224.9425.
8
7
5
.1.2.3. 7-Bromo-5-nitroisatin (4). To
a
SO
solution of NaNO
(6.8 mL) was added
3
(t, 1H, J = 7.6 Hz, H arom), 6,19 (m, 2H, 7-H et H arom), 5,89 (s,
2H, NH
2
). IR = 3176, 1714, 1482, 1274, 1004. HRMS (EI) [M]+
Å
(
0.337 g, 3.97 mmol) in concentrated H
2
4
dropwise a solution of 7-bromoisatin 3 (0.898 g, 3.97 mmol) in
concentrated H SO (5.7 mL) for a period of 1 h at 0 °C. The reac-
tion mixture was then poured into ice water (30 mL), and the pre-
11 3 2
(C16H N O ): calcd 277.08513, found 277.0838.
2
4
0
5.1.5. General procedure for the synthesis of 3 -monoxime
indirubin derivatives
cipitate was collected by filtration and washed with water to give
1
4
. Yield : 85%. H NMR (400 MHz, DMSO-d
6
) d ppm 11.92 (s, 1H,
Under an inert atmosphere of argon, to a stirred solution of
indirubin derivatives 12, 13, 17, 18, 22 (3 mmol) in pyridine (5 mL)
was added 2.1 g (30 mmol) of hydroxylamine hydrochloride. The
mixture was irradiated during 10 min. The irradiation in CEM oven
was programmed to maintain a constant temperature (110 °C) with
a maximal power output of 150 W. After cooling, the pyridine was
removed under reduced pressure. The crude material was succes-
sivelyand intensivelywashed with coldwater and acetone. Thesolid
13
NH), 8.61 (s, 1H, H-6), 8.18 (s, 1H, H-4). C NMR (100 MHz,
DMSO-d ) d ppm 181.60, 160.16, 154.25, 143.00, 134.80, 119.57,
18.20, 140.38. IR = 3185, 1750, 1612, 1528, 1340. HRMS (EI)
6
1
[
+Å
79
8 3 4
M] (C H NO Br) calcd 269.92762, found 269.9279.
5
5
.1.3. Synthesis of 6-N-substituted-isatins
.1.3.1. 6-Nitroisatin (6). Under an inert atmosphere of argon, to
a solution of 6-nitro-3-indolaldehyde (1.71 g, 9.0 mmol) in acetic
acid was added dropwise over a period of 15 min a solution of
chromium trioxide (3.6 g, 36.0 mmol) in acetic acid (5 mL) and
water (1.6 mL). The dark brown solution was stirred at room tem-
perature for 30 h. The bright orange solid was filtered, washed with
was dried over P
2
O
5
under reduced pressure (14–84%).
0
0
0
5.1.5.1. (2 Z,3 E)-7-Bromo-5-nitroindirubin-3 -oxime
1
(23). Yield: 52%. Mp >260 °C. H NMR (400 MHz, DMSO-d
6
) d ppm
0
0
13.99 (s, 1H, N OH), 12.02 (s, 1H, N H), 11.59 (s, 1H, NH), 9.47 (s, 1H,
H-4), 8.26 (d, 1H, J = 7.6 Hz, H arom), 8.19 (s, 1H, H-6), 7.51 (d, 1H,
J = 7.6 Hz, H arom), 7.45 (t, 1H, J = 7.6 Hz, H arom), 7.12 (t, 1H,
J = 7.6 Hz, H arom). IR = 3096, 2904, 1718, 1677, 13337, 1226. HRMS
water, dried, and recrystallized from ethanol. Yield : 58% . mp
1
>
260 °C . H NMR (400 MHz, DMSO-d
6
) d ppm 11.31 (s, NH), 7.85
(
(
dd, 1H, J = 2.0 and 8.0 Hz, H-5), 7.76 (d, 1H, J = 8.0 Hz, H-4), 7.54
+Å
79
d, 1H, J = 2.0 Hz, H-7). IR = 3191, 1750, 1549, 1328, 1213, 736 cm
(EI) [M] (C16
9
H N
4
O
4
Br) : calcd 399.98072, found 399.9803.
ꢁ1
+Å
.
8 4 2 4
HRMS (EI) [M] (C H N O ): calcd 192.01711, found 192.0180.
0
0
0
5
.1.5.2. (2 Z, 3 E)-6-Nitroindirubin-3 -oxime (24). Yield: 14%. Mp
1
0
5
.1.4. General procedure for the synthesis of indirubin
6
>260 °C. H NMR (400 MHz, DMSO-d ) d ppm 12.17 (s, 1H, N H),
derivatives
11.15 (s, 1H, NH), 8.75 (dd, 1H, J = 4.0 and 8.8 Hz, H arom), 8.24 (d,
1H, J = 8.0 Hz, H arom), 7.83 (d, 1H, J = 3.2 and 8.8 Hz, H arom),
7.64 (s, 1H, H-7), 7.52 (dd, 1H, J = 3.2 and 8.0 Hz, H arom), 7.44 (t,
1H, J = 7.2 Hz, H arom), 7.39 (t, 1H, J = 4.0 Hz), 7.12 (td, 1H, J = 4.0
and 7.2 Hz). IR = 3225, 2917, 1721, 1668, 1566, 1330, 608.
Under an inert atmosphere of argon, a solution of isatin deriva-
tives 4, 6 (3 mmol), indoxyl acetate 10 or 11 (5 mmol) in methanol
(
2 3
15 mL) was vigorously stirred with Na CO . After 1 h under stir-
ring at 45 °C, the dark violet residue was filtered and successively
and intensively washed with methanol and cold water. The solid
0
0
0
0
was dried over P
2
O
5
under reduced pressure (45–95%).
5.1.5.3. (2 Z, 3 E)-5 -Bromo-6-nitroindirubin-3 -oxime (29). Yield:
1
1
4%. Mp >260 °C. H NMR (400 MHz, DMSO-d
N H), 11.08 (s, 1H, NH), 8.72 (d, 1H, J = 8.8 Hz, H-4), 8.34 (d, 1H,
J = 1.2 Hz, H-7), 7.82 (dd, 1H, J = 1.2 and 8.8 Hz, H-5), 7.65 (d, 1H,
J = 1.6 Hz, H-4 ), 7.62 (dd, 1H, J = 1.6 and 8.8 Hz, H-6 ), 7.48 (d, 1H,
J = 8.8 Hz, H-7 ). IR = 3186, 2929, 1714, 1569, 1333.
6
) d ppm 12.16 (s, 1H,
0
0
5
>
.1.4.1. (2 Z)-7-Bromo-5-nitroindirubin (12). Yield: 45%. Mp
1
0
260 °C. H NMR (400 MHz, DMSO-d
6
) d ppm: 11.76 (s, 1H, N H),
0
0
1
1.34 (s, 1H, NH), 9.67 (s, 1H, H-4), 8.30 (s, 1H, H-6), 7.59 (d, 1H,
0
J = 8.0 Hz, H arom), 7.50 (t, 1H, J = 7.2 Hz, H arom), 7.33 (d, 1H,
J = 8.0 Hz, H arom), 6.94 (t, 1H, J = 7.2 Hz, H arom). IR = 3103,
+
Å
79
0
0
0
1
677, 1613, 1465, 1334, 763. HRMS (EI) [M] (C16
8
H N
3
O
4
Br):
5.1.5.4. (2 Z, 3 E)-6-Aminoindirubin-3 -oxime (33). Yield: 84%.
Mp >260 °C. H NMR (400 MHz, DMSO-d
N H), 8.82 (s, 1H, NH), 8.15 (d, 1H, J = 8.0 Hz, H arom), 7.59 (d, 1H,
J = 8.0 Hz, H arom), 7.41 (d, 1H, J = 7.6 Hz, H arom), 7.37 (d, 1H,
J = 8.0 Hz, H arom), 7.35 (d, 1H, J = 7.6 Hz, H arom), 7.25 (d, 1H,
J = 8.0 Hz, H arom), 6.96 (t, 1H, J = 7.2 Hz, H arom), 6.88 (t, 1H,
J = 7.2 Hz, H arom), 3.26 (s large, 2H, NH
1322, 1200. HRMS (EI) [M}] (C16
277.0860.
1
calcd 384.96982, found 384.9687.
6
) d ppm 12.81 (s, 1H,
0
5
.1.4.2. (2 Z)-6-Nitroindirubin (13). Yield: 35%. mp >260 °C . 1H
0
0
NMR (400 MHz, DMSO-d
6
) d ppm 11.43 (s, NH), 11.27 (s, N H), 8.88
(
(
d, 1H, J = 8.8 Hz, H-4), 7.91 (dd, 1H, J = 2.0 and 8.8 Hz, H-5), 7.68
0
d, 1H, J = 7.6 Hz, H-4 ), 7.66 (d, 1H, J = 2.0 Hz, H-7), 7.60 (t, 1H,
2
). IR = 3108, 2960, 1713,
H N O ) : calcd 277.08513 found
0
0
+Å
J = 7.6 Hz, H-5 ), 7.40 (t . 1H, J = 7.6 Hz, H-6 ), 7.09 (t, 1H, J = 7.6 Hz,
H-7 ). IR = 3411, 1738, 1673, 1589, 1463, 1331, 1183, 87 cm . HRMS
(
11 3 2
0
ꢁ1
EI) [M]+ (C16
Å
9
H N
3 4
O ): calcd 307.05931, found 307.0592.
0
0
0
0
5
.1.5.5. 5-Nitro-1H,1 H-[3,3 ]biindolylidene-2,2 -dione or (3 Z)-
0
0
ꢁ1
5
.1.4.3. (2 Z)-5 -7-Dibromo-5-nitroindirubin (17). Yield: 56%.
5-nitroisoindigo (35). Yield: 85%. Mp >260 °C. IR:
3145 (NH), 1705 (C@O), 1682 (C@O) 1525 (NO
NMR d (400 MHz, DMSO-d ): 11.43 (s, 1H, NH), 10.87 (s, 1H, NH),
9.06 (d, 1H, J = 7.6 Hz, 4-H), 8.25 (d, 1H, J = 8.8 Hz, 7-H), 7.38 (t,
m
max (cm ):
1
Mp >260 °C. IR = 3282, 3080, 1706, 1679, 1609, 1462, 1285, 823.
2
) 1339, 1077. H
HRMS (EI) [M]+ (C16
Å
H
7
N
3
O
4
79
Br
2
): calcd 462.88033, found
6
4
62.8803.