(
(
CH), 124.03 (CH), 124.02 (CH), 123.1 (C), 114.9 (CH), 84.1
1 h after which time saturated brine (50 ml) was added. The
C), 36.4 (CH ), 28.0 (Me).
organic layer was separated and the aqueous extracted with
ether (2 × 30 ml). The combined ethereal layers were further
dried over Na SO , filtered and evaporated in vacuo. The result-
2
tert-Butyl 3,3,-dimethyl-2-oxo-2,3-dihydroindole-1-carboxylate
2
4
ing yellow oil was purified by flash chromatography on silica
eluting with light petroleum–ether (85 : 15) to give diazo-
tert-Butyl 2-oxo-2,3-dihydroindole-1-carboxylate (16.7 g, 71.6
mmol) was dissolved in dry THF (175 ml) under nitrogen.
Methyl iodide (13.5 ml, 214.8 mmol) was added and the mix-
ture cooled on ice. Sodium hydride (60%; 6.3 g, 157.5 mmol)
was added portionwise over 0.75 h maintaining the internal
temperature below 10 ЊC. After complete addition the reaction
mixture was stirred for a further 3 h before water (500 ml) was
added. The resulting solution was then extracted into di-
chloromethane (4 × 100 ml), the combined organic extracts
washed with saturated brine (2 × 200 ml), and dried further
ϩ
thioamide 8 (1.24 g, 61%) as a yellow oil, (Found: M ϩ Na ,
3
40.0733. C H N O S ϩ Na requires 340.0732); ν
(film)/
15
15
3
3
max
Ϫ1
cm 2976, 2927, 2143, 1732 (br), 1678 (br), 1460, 1352, 1236,
136, 1037, 752; δ (400 MHz; CDCl ) 7.22 (4 H, m), 4.23 (2 H,
1
H
3
q, J 7.1), 1.50 (6 H, s), 1.24 (3 H, t, J 7.1); δ (75.5 MHz; CDCl )
C
3
2
14.1 (C), 163.4 (C), 159.0 (C), 140.8 (C), 139.3 (C), 127.9
(
CH), 125.0 (CH), 123.2 (CH), 111.3 (CH), 75.2 (C), 62.1
(
CH ), 56.2 (C), 28.5 (Me), 14.2 (Me); m/z (EI) 289 (M–N ,
2
2
9
3%), 243 (74), 217 (95), 202 (57), 177 (76), 176 (89), 162 (59),
over Na SO . Removal of the solvent in vacuo gave a red solid
which was purified by chromatography on silica eluting with
light petroleum–ether (4 : 1) to give the title compound (12.5 g,
2
4
161 (100).
N-Methylmaleimide cycloadduct 10
6
7%) as a colourless solid, mp 45–46 ЊC (from ethyl acetate–
Diazothioamide 8 (195 mg, 0.62 mmol) in dry toluene (3.5 ml)
was added dropwise over a period of 20 min to a solution of
N-methylmaleimide (75 mg, 0.68 mmol), dirhodium() tetra-
acetate (cat 1.4 mg) in dry toluene (2 ml) at 90 ЊC. The resulting
solution was stirred for an additional 2 h, allowed to cool and
filtered. Evaporation of the solvent gave a brown solid which
was purified by chromatography on silica eluting with light pet-
roleum–ethyl acetate (10 50%) to give (i) the exo-cycloadduct
light petroleum); (Found: C, 69.0; H, 7.5; N, 5.3. C H NO
requires C, 68.9; H, 7.3; N, 5.4%); νmax (KBr)/cm 2980, 1772,
15
19
3
Ϫ1
1
7
730, 1608, 1481, 1348, 1254, 1149, 779; δ (300 MHz; CDCl )
.85 (1 H, d, J 8.2), 7.33–7.13 (3 H, m), 1.66 (9 H, s), 1.43 (6 H,
H
3
s); δ (75.5 MHz; CDCl ) 179.8 (C), 149.5 (C), 138.3 (C), 134.5
C
3
(
C), 127.9 (CH), 124.5 (CH), 122.2 (CH), 115.0 (CH), 84.3 (C),
4
2
4.5 (C), 28.1 (Me), 25.3 (Me); m/z (CI) 279 (M ϩ NH , 100%),
62 (59).
4
1
0 (163 mg, 66%) as colourless prisms, mp 189–190 ЊC (from
ethyl acetate); (Found: C, 59.7; H, 4.8; N, 6.6. C H N O S
20
20
2
5
3
,3-Dimethyl-1,3-dihydroindol-2-one
Ϫ1
requires C, 60.0; H, 5.0; N, 7.0%); νmax (KBr)/cm 2966, 2951,
1784, 1729 (br), 1707 (br), 1481, 1435, 1383, 1356, 1311, 1286,
1109, 1030, 769; δ (400 MHz; CDCl ) 7.50 (1 H, d, J 7.6), 7.23
tert-Butyl 3,3,-dimethyl-2-oxo-2,3-dihydroindole-1-carboxylate
8.41 g, 32.3 mmol) was dissolved in dichloromethane (60 ml)
(
H
3
and cooled to 0 ЊC. TFA (30 ml) was added dropwise and the
resulting mixture was stirred at 0 ЊC for 0.5 h. After this time the
mixture was evaporated in vacuo and the residue purified by
flash chromatography on silica eluting with light petroleum–
ethyl acetate (3 : 1) to give the title compound (5.11 g, 98%) as a
(2 H, m), 7.12 (1 H, t, J 6.9), 4.39 (2 H, q, J 7.1), 4.09 (1 H, d,
J 6.8), 3.95 (1 H, d, J 6.8), 3.04 (3 H, s), 1.70 (3 H, s), 1.50 (3 H,
s), 1.30 (3 H, t, J 7.1); δ (100 MHz; CDCl ) 172.7 (C), 172.3
(C), 170.1 (C), 163.0 (C), 139.4 (C), 138.4 (C), 128.1 (CH),
125.0 (CH), 122.1 (CH), 114.1 (CH), 92.3 (C), 71.9 (C), 63.1
C
3
26
pale brown solid, mp 149–151 ЊC (from ethyl acetate) (lit., mp
52–153 ЊC); δ (300 MHz; CDCl ) 9.42 (1 H, br s), 7.21 (2 H,
(CH ), 55.6 (CH), 48.9 (CH), 44.4 (C), 28.5 (Me), 25.6 (Me),
2
ϩ
1
22.8 (Me), 14.0 (Me); m/z (EI) 400 (M , 33%), 299 (29), 289
H
3
m), 7.02 (2 H, m), 1.42 (6 H, s); δ (75.5 MHz; CDCl ) 184.6
(100), 243 (42); (ii) the endo-cycloadduct (22 mg, 9%) as pale
brown plates, mp 181–182 ЊC (from ethyl acetate); (Found: C,
60.1; H, 5.1; N, 6.5. C H N O S requires C, 60.0; H, 5.0; N,
C
3
(
C), 140.0 (C), 136.2 (C), 127.6 (CH), 122.5 (CH), 122.4 (CH),
1
10.0 (CH), 44.7 (C), 24.3 (Me).
20
Ϫ1
20
2
5
7
1
.0%); νmax (KBr)/cm 2958, 2927, 1782, 1745 (br), 1713 (br),
483, 1431, 1394, 1306, 1232, 1090, 978, 766; δH (400 MHz;
3
,3-Dimethyl-1,3-dihydroindole-2-thione 7
CDCl ) 7.41 (1 H, d, J 7.9), 7.17 (3 H, m), 4.31 (3 H, m), 4.19 (1
3
3
,3-Dimethyl-1,3-dihydroindol-2-one (1.64 g, 10.2 mmol) was
H, d, J 8.4), 2.75 (3 H, s), 1.97 (3 H, s), 1.45 (3 H, s), 1.40 (3 H, t,
J 7.1); δ (100 MHz; CDCl ) 172.3 (C), 170.6 (C), 163.7 (C),
dissolved in dry toluene (20 ml) under nitrogen. Lawesson’s
reagent (2.17 g, 5.2 mmol) was added and the reaction mixture
heated at reflux for 1.5 h. After this time the reaction mixture
was allowed to cool and poured into water (75 ml). The organic
layer was separated and the aqueous extracted with ether (3 ×
C
3
1
1
61.9 (C), 141.2 (C), 134.7 (C), 128.3 (CH), 125.6 (CH),
22.6 (CH), 112.4 (CH), 92.1 (C), 69.0 (C), 63.2 (CH ), 56.3
2
(
(
(
CH), 52.8 (CH), 43.6 (C), 32.4 (Me), 25.1 (Me), 22.3 (Me), 14.1
Me); m/z (EI) 400 (M , 22%), 368 (39), 295 (87), 289 (50), 224
70); and (iii) the thioisomünchnone 9 (34 mg, 19%), data given
ϩ
5
0 ml). The combined organic layers were washed with satur-
ated brine (2 × 50 ml) and dried further over Na SO . Removal
2
4
below.
of the solvents in vacuo gave a pale orange solid which was
purified by flash chromatography on silica eluting with hexane–
ethyl acetate (5 25%) to give the title compound 7 (1.34 g,
Thioisomünchnone 9
Diazothioamide 8 in toluene was treated with dirhodium()
tetraacetate at 80 ЊC for 1.5 h. Evaporation of the solvent and
chromatography on silica eluting with ethyl acetate gave the
title compound (80–85%) as an amorphous yellow solid, mp
9
1%) as a pale yellow solid, mp 107–108 ЊC (from ethanol)
20
(
lit., mp 109–110 ЊC); δ (300 MHz; CDCl ) 10.79 (1 H, br s),
H
3
7
.27 (2 H, m), 7.16 (1 H, t, J 7.1), 7.08 (1 H, d, J 7.7), 1.47 (6 H,
s); δ (75.5 MHz; CDCl ) 214.2 (C), 141.3 (C), 140.7 (C), 127.9
C
3
1
78–179 ЊC (from ethanol); (Found: C, 62.2; H, 5.1; N, 4.6.
(
CH), 124.1 (CH), 123.1 (CH), 110.3 (CH), 55.3 (C), 27.7 (Me).
C H NO S requires C, 62.3; H, 5.2; N, 4.8%); (Found: 2M ϩ
1
5
15
3
ϩ
H , 579.1639. C H N O S ϩ H requires 579.1624); νmax
30
30
2
6 2
Ethyl 2-diazo-3-(3,3-dimethyl-2-thioxo-2,3-dihydroindol-yl)-3-
oxopropanoate 8
Ϫ1
(
1
KBr)/cm 2989, 2970, 1681, 1662, 1581, 1467, 1438, 1374,
340, 1188, 1070, 761; δH (300 MHz; CDCl ) 8.40 (1 H, d,
3
3
,3-Dimethyl-1,3-dihydroindole-2-thione 7 (1.13 g, 6.4 mmol)
was dissolved in dry ether (30 ml) under nitrogen and cooled to
ЊC. Sodium hydride (60%, 282 mg, 7.0 mmol) was added and
the resulting mixture stirred to room temperature over 10 min.
J 7.4), 7.45 (3 H, m), 4.35 (2 H, d, J 7.2), 1.65 (6 H, s), 1.37 (3 H,
t, J 7.2); δ (75.5 MHz; CDCl ) 173.2 (C), 163.2 (C), 157.1 (C),
142.9 (C), 138.3 (C), 129.1 (CH), 127.9 (CH), 122.6 (CH), 115.7
C
3
0
(CH), 91.4 (C), 60.5 (CH ), 49.0 (C), 27.1 (Me), 14.7 (Me);
2
21
Ethyl diazomalonyl chloride (1.47 g, 8.3 mmol) was added in
one portion and the reaction mixture stirred for an additional
m/z (FAB) 601 (2M ϩ Na, 61%), 579 (2M ϩ H, 14), 312 (100)
(M ϩ Na), 290 (28), 244 (86).
O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 2 7 1 6 – 2 7 2 2
2719