1H-Pyrrolo[2,3-b]pyridine-2,3-dione-2-oxime 10
J4,6 1.6, H(4)], 8.06 [1H, s, H(2)] and 8.39 [1H, dd, J6,4 1.6 and
J
6,5 4.7, H(6)]; dC 21.19 (CH3), 26.53 (CH3), 114.27, 117.64 (quat),
To a suspension of 1,2-dihydropyrrolo[2,3-b]pyridin-3-one 8K
(140 mg, 1.04 mmol) in water (40 cm3) and acetic acid (0.2 cm3) was
added sodium nitrite (135 mg, 1.73 mmol) and the mixture was
stirred at room temperature for 1 h. The mixture was filtered,
the filtrate extracted with dichloromethane (3 ¥ 100 cm3), the
organic extracts dried (MgSO4) and the solvent removed by rotary
evaporation to yield crude 1H-pyrrolo[2,3-b]pyridine-2,3-dione-2-
oxime 10 (38 mg, 22%); (Found: M+ 163.0382, C7H5N3O2 requires
M 163.0382); dH ([2H6]DMSO) 7.00 [1H, dd, J5,6 5.6 and J5,4 7.6,
H(5)], 7.95 [1H, dd, J4,6 1.7 and J4,5 7.6, H(4)], 8.42 [1H, dd, J6,5
5.6 and J6,4 1.7, H(6)], 10.97 (1H, br s) and 11.97 (1H, br s); dC
([2H6]DMSO) 109.31 (quat), 113.53 (quat), 116.64, 132.80, 155.93,
163.08 (quat) and 179.29 (quat); m/z 163 (M+, 83%), 146 (54), 134
(58), 119 (100), 118 (49) and 91 (44).
119.09, 127.23, 132.63 (quat), 145.20, 147.88 (quat), 168.20 (quat)
and 169.03 (quat); m/z 218 (M+, 4%), 176 (19), 134 (100), 133 (31),
79 (21) and 78 (30).
2,2-Dimethyl-5-(3-oxo-2,3-dihydropyrrolo[2,3-b]pyridin-1-
ylmethylene)-1,3-dioxane-4,6-dione 16
Methoxymethylene Meldrum’s acid 15 (142 mg, 0.76 mmol)
was added to a suspension of 1,2-dihydropyrrolo[2,3-b]pyridin-
3-one 8K (122 mg, 0.91 mmol) in acetonitrile (7 cm3) and
the mixture was stirred at room temperature for 20 h.
The resulting solution was filtered through Celite, the sol-
vent concentrated to 0.5 cm3 and the precipitate collected
to yield 2,2-dimethyl-5-(3-oxo-2,3-dihydropyrrolo[2,3-b]pyridin-
1-ylmethylene)-1,3-dioxane-4,6-dione 16 (30 mg, 14%); (Found:
M+ 288.0746, C14H12N2O5 requires M 288.0746); dH 1.99 (6H, s, 2
CH3), 4.87 (2H, s, CH2), 7.37 [1H, dd, J5,4 6.6 and J5,6 4.9, H(5)],
8.13 [1H, dd, J4,5 6.6 and J4,6 1.8, H(4)], 8.71 [1H, dd, J6,4 1.8 and
J6,5 4.9, H(6)] and 9.79 (1H, s, alkene); dC 26.95 (2CH3), 59.10
(CH2), 92.19 (quat), 103.94 (quat), 117.10 (quat), 122.04, 133.70,
146.00, 156.34, 160.03 (quat), 163.17 (quat), 163.32 (quat) and
191.62 (quat); m/z 288 (M+, 0.4%), 230 (55), 186 (23), 158 (33),
152 (21) and 119 (100).
2-[2-Oxo-1,2-dihydro-indol-(3Z)-ylidene]-1,2-dihydropyrrolo[2,3-
b]pyridin-3-one 12
To a solution of isatin 11 (87 mg, 0.58 mmol) in methanol
(10 cm3) was added solid 1,2-dihydropyrrolo[2,3-b]pyridin-3-one
8K (81 mg, 0.60 mmol) followed by N,N-diisopropylethylamine
(ca. 0.066 cm3) and the mixture was stirred at room temperature
for 30 min. The resulting precipitate was collected and washed
with methanol to yield 2-[2-oxo-1,2-dihydro-indol-(3Z)-ylidene]-
1,2-dihydropyrrolo[2,3-b]pyridin-3-one 12 (27 mg, 17%); mp >
330 ◦C; (Found: M+ 263.0696, C15H9N3O2 requires M 263.0695);
6-Hydroxypyrido[3,2-b]pyrrolizin-5-one 17
l
max (methanol) 505 nm (e 7900 mol-1 cm-1); dH ([2H6]DMSO) 6.93
(1H, m, Ar–H), 7.05 (1H, m, Ar–H), 7.12 [1H, dd, J5,4 7.5 and J5,6
5.1, H(5)], 7.30 (1H, m, Ar–H), 8.11 [1H, dd, J4,5 7.5 and J4,6 1.7,
H(4)], 8.50 (1H, dd, J6,4 1.7 and J6,5 5.1, H(6)], 8.68 (1H, m, Ar–H),
10.79 (1H, br s, NH) and 11.04 (1H, br s, NH); dC ([2H6]DMSO)
108.59 (quat), 110.32, 113.23 (quat), 118.17, 121.28 (quat), 121.98,
125.22, 130.55, 133.98, 137.94 (quat), 141.72 (quat), 156.06, 163.29
(quat), 171.40 (quat) and 186.45 (quat); m/z 264 (77%), 263 (M+,
100), 236 (20), 235 (57), 207 (15) and 78 (50).
FVP of 2,2-dimethyl-5-(3-oxo-2,3-dihydropyrrolo[2,3-b]pyridin-
1-ylmethylene)-1,3-dioxane-4,6-dione 16 (29 mg, 0.10 mmol, Tf
◦
650 ◦C, Ti 160 C, P 2.3 ¥ 10-2 Torr, t 10 min) yielded 6-
hydroxypyrido[3,2-b]pyrrolizin-5-one 17 (5 mg, 27%); (Found: M+
186.0429. C10H6N2O2 requires M 186.0429); dH ([2H6]DMSO) 5.94
[1H, d, J7,8 3.0, H(7)], 7.17 [1H, dd, J3,4 7.4 and J3,2 5.1, H(3)], 7.50
[1H, d, J8,7 3.0, H(7)], 7.91 [1H, dd, J4,3 7.4 and J4,2 1.6, H(4)] and
8.36 [1H, dd, J2,4 1.6 and J2,3 5.1, H(2)]; dC ([2H6]DMSO) 106.92,
116.35 (quat), 120.04, 121.71, 123.64 (quat), 132.10, 151.28, 151.48
(quat), 154.19 (quat) and 172.75 (quat); m/z 187 (12%), 186 (M+,
100), 160 (12), 104 (17), 103 (11) and 77 (12).
3-Acetoxy-1H-pyrrolo[2,3-b]pyridine 13
1,2-Dihydropyrrolo[2,3-b]pyridin-3-one 8K (32 mg, 0.24 mmol)
was placed in a 10 cm3 round bottomed flask, and acetic anhydride
(0.5 cm3) added. The contents were swirled, and immediately
evacuated to 2.8 ¥ 10-2 Torr. After removal of solvent, 1H NMR
analysis of the product mixture showed a 1 : 2 ratio of 3-acetoxy-
1-acetyl-1H-pyrrolo[2,3-b]pyridine 14 (see below) and 3-acetoxy-
1H-pyrrolo[2,3-b]pyridine 13 identified by its 1H NMR spectrum;
dH 2.36 (3H, s, acetyl), 7.09 [1H, dd, J5,4 7.9 and J5,6 4.8, H(5)],
7.44 [1H, s, H(2)], 7.90 [1H, dd, J4,5 7.9 and J4,6 1.4, H(4)] and 8.26
[1H, dd, J6,4 1.4 and J6,5 4.8, H(6)].
4-Acetyltetrazolo[1,5-a]quinoline 19
3-Acetyl-2-chloroquinoline 18 (1.60 g, 7.79 mmol) (ESI†) and
sodium azide (1.23 g, 19.1 mmol) were suspended in a mixture
of aqueous ethanol (10%,◦110 cm3) and hydrochloric acid (10%,
5.5 cm3) and heated at 95 C for 3 h. The solvents were removed
by rotary evaporation, water (ca. 35 cm3) was added and the
resulting precipitate collected and washed with water to yield◦4-
acetyltetrazolo[1,5-a]quinoline 19 (1.53 g, 91%); mp 186–188 C
(from acetonitrile); (Found: M+ 212.0698. C11H8N4O requires M
212.0698); dH 3.12 (3H, s, acetyl), 7.79 (1H, ddd, J 0.9, 7.2 and
8.1, Ar–H), 8.01 (1H, ddd, J 0.6, 7.2 and 7.8, Ar–H), 8.14 (1H,
dd, J 0.9 and 7.8, Ar–H), 8.67 [1H, s, H(4)] and 8.72 (1H, dd, J
0.6 and 8.1, Ar–H); dC 30.95 (CH3), 116.88, 122.49 (quat), 122.69
(quat), 128.50, 130.94, 131.79 (quat), 133.46, 135.97, 146.17 (quat)
and 193.72 (quat); nmax 1693 (acetyl), 1618, 1599, 1561, 1465, 1409
and 1091 cm-1; m/z 212 (M+, 21%), 184 (100), 142 (62), 129 (45),
115 (65) and 114 (50).
3-Acetoxy-1-acetyl-1H-pyrrolo[2,3-b]pyridine 14
1,2-Dihydropyrrolo[2,3-b]pyridin-3-one 8K (36 mg, 0.27 mmol)
was dissolved in acetic anhydride (2 cm3) and heated with a hot
air blower for 10 min. The excess reagent was evaporated un-
der reduced pressure to yield 3-acetoxy-1-acetyl-1H-pyrrolo[2,3-
b]pyridine 14 (52 mg, 88%); (Found: M+ 218.0691. C11H10N2O3
requires M 218.0691); dH 2.37 (3H, s, acetyl), 3.04 (3H, s, acetyl),
7.22 (1H, dd, J5,4 7.9 and J5,6 4.7, H(5)], 7.82 [1H, dd, J4,5 7.9 and
This journal is
The Royal Society of Chemistry 2010
Org. Biomol. Chem., 2010, 8, 5166–5173 | 5171
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