Synthesis of benzo[f]indole-4,9-dione and benzo[b]carbazole-6,11-dione derivatives via one-pot sequential C,N-dialkylation of enaminones of β-diketones and ketoesters by 2,3-dichloronaphthoquinone

Article abstract of DOI:10.1055/s-2006-948171

Direct one-pot syntheses of benzo[f]indole-4,9-dione and benzo[b]carbazole-6,11-dione derivatives have been achieved in moderate to high yields via sequential C,N-dialkylation of the monoenamines of β-dicarbonyl compounds (the β-enaminones) by 2,3-dichlor

Full text of DOI:10.1055/s-2006-948171

LETTER
1913
Synthesis of Benzo[f]indole-4,9-dione and Benzo[b]carbazole-6,11-dione
Derivatives via One-Pot Sequential C,N-Dialkylation of Enaminones of
b-Diketones and Ketoesters by 2,3-Dichloronaphthoquinone
B
enzo[
f
]
indole-4,9
u
-dione and
B
a
enzo[
b
]ca
r
-
bazole-6
Y
,11-dione
D
erivati
o
ves u Hu, Yun Liu, Miao Ye, Jian-Hua Xu*
Department of Chemistry, Nanjing University, Nanjing 210093, P. R. of China
Fax +86(25)83317761; E-mail: xujh@nju.edu.cn
Received 24 February 2006
structure–activity relationship is still hampered by the
lack of simple and efficient one-pot synthesis of the two
classes of compounds from easily accessible starting
materials. Following our recent work on the synthesis of
naphtho[b]furan-4,9-dione derivatives via the C,O-di-
alkylation of the enolate of 1,3-dicarbonyl compounds by
2,3-dichloronaphthoquinone (1),21 we became interested
in the possibility of synthesizing benzo[f]indole-4,9-di-
ones and benzo[b]carbazole-6,11-diones via the reaction
of 1 with the monoenamine of 1,3-dicarbonyl compounds
(the b-enaminones). b-Enaminones are known to be ambi-
dent nucleophiles that may react with electrophiles with
either the N or the Ca atom, or with both sequentially,22
and their application in the synthesis of N-containing
heterocycles by the reactions with 1,2-electrophilic spe-
cies, such as benzoquinone,23 a,b-unsaturated carbonyl
compounds,24 1,2,4-triazines,25 alkynyl ketones or propi-
olates,26 bromoacetates,27 among others,22 has been ac-
tively researched. However, direct alkylations at both the
Ca and N atoms of b-enaminones via nucleophilic substi-
tution of halogen atoms at a C=C bond have rarely been
reported. To our knowledge, there was only one report on
such reactions in which three benzo[f]indole-4,9-diones
were synthesized by the reaction of 1 with the mono-
enamine of b-ketoesters in a stepwise way.17 We report
here the direct one-pot syntheses of both benzo[f]indole-
4,9-diones 3 and benzo[b]carbazole-6,11-diones 5, 7 and
8 via the C,N-dialkylation of a series of acyclic b-enami-
nones 2 and cyclic b-enaminones 4 and 6 by 1 (Scheme 1,
Scheme 2 and Table 1).
Abstract: Direct one-pot syntheses of benzo[f]indole-4,9-dione
and benzo[b]carbazole-6,11-dione derivatives have been achieved
in moderate to high yields via sequential C,N-dialkylation of the
monoenamines of b-dicarbonyl compounds (the b-enaminones) by
2,3-dichloronaphthoquinone
Key words: benzo[f]indole-4,9-dione, benzo[b]carbazole-6,11-di-
one, enaminone, 2,3-dichloronaphthoquinone, C,N-dialkylation
Naturally occurring quinones constitute an important
class of natural products1 that have a wide range of biolog-
ical activity resulting from their ability to intercalate with
DNA via charge transfer interaction with the electron-rich
DNA bases and their effect to interfere with the basic nu-
clear processes via redox cycling of the quinone and gen-
eration of active oxygen species.2 A basic structural unit
in these quinone natural products is the indoloquinone
moiety.3 As benzannulated indoloquinones, the synthesis
of benzo[f]indole-4,9-diones is drawing much attention in
relation to the synthesis of the mitomycin alkaloid
congeners4 and because of their own diversified bio-
logical activity, such as antineoplastic, antibacterial,
virus-static, fungicidic, and anticoagulant activity.5
Benzo[b]carbazole-6,11-diones (indolonaphthoquinones)
as bisannulated indoloquinones are also important syn-
thetic targets since they were once assigned as the
framework of the natural antibiotics kinamycin.6 Al-
though the kinamycin structure was later revised to
have a benzo[b]fluorene rather than benzo[b]carbazole
skeleton,7 the structural similarity of the indolonaphtho-
quinones with their naturally occurring aza analogues
ellipticine quinones,8 calothrixins A and B,9 and the
carbazole alkaloids,10 makes them continue to be interest-
ing target compounds for biological investigation. Indeed,
benzo[b]carbazole-6,11-diones have been found in recent
years to be biologically important on their own because of
their promising versatile antitumor activity.11
O
COR
R1
O
Cl
Cl
O
NHR2
R1
+
N
R
R2
O
O
1
2
3
2a R = R1 = Me, R2 = Ph
3a R = R1 = Me, R2 = Ph
Several synthetic methods have been reported for ben-
zo[f]indole-4,9-diones12–17 and benzo[b]carbazole-6,11-
diones.4,7,18–20 However, a majority of the present methods
are based on rather long reaction sequences. As a result,
further investigation of the biological activity and the
2b R = R1 = Me, R2 = p-MeOPh
2c R = R1 = Me, R2 = p-MeCOPh
2d R = OEt, R1 = Me, R2 = Ph
2e R = R2 = Ph, R1 = Me
3b R = R1 = Me, R2 = p-MeOPh
3c R = R1 = Me, R2 = p-MeCOPh
3d R = OEt, R1 = Me, R2 = Ph
3e R = R2 = Ph, R1 = Me
2f R = OEt, R1 = Me, R2 = n-Bu
3f R = OEt, R1 = Me, R2 = n-Bu
Scheme 1
SYNLETT 2006, No. 12, pp 1913–1917
0
1
.0
8
.2
0
0
6
Advanced online publication: 24.07.2006
DOI: 10.1055/s-2006-948171; Art ID: W04506ST
© Georg Thieme Verlag Stuttgart · New York

1914
H.-Y. Hu et al.
LETTER
O
O
O
O
O
Cl
K2CO3
+
MeCN, reflux
Cl
N
NHR
O
R
4
5
1
4a R = Ph
5a R = Ph
4b R = p-MeOPh
4c R = p-ClPh
5b R = p-MeOPh
5c R = p-ClPh
HO
O
O
O
O
O
O
O
Cl
Cl
K2CO3
+
+
MeCN, reflux
N
N
NHR
O
R
R
8
1
6
7
6a R = Ph
6b R = 1-Naphthyl
7a R = Ph
7b R = 1-Naphthyl
8a R = Ph
8b R = 1-Naphthyl
O
O
O
O
O
Cl
NHR2
R1
Cl
R
N
R2
R1
O
R
I
II
Scheme 2
Preliminary experiments showed that reaction of 1 with the enaminones 2a–f conducted in DMF or MeCN with
the enaminone 2e did proceed in the presence of sodium potassium carbonate as a solid base gave better results.
carbonate to give the desired benzo[f]indole-4,9-dione 3e. Under these conditions, the reactions proceeded smoothly
The yield, however, is highly sensitive to the choice of the in all cases at 75–80 °C to give the corresponding products
base and the solvent. After examining different combina- 3a–f in moderate to high yields (Table 1). The structures
1
tions of solvent and base, we found that reactions of 1 with of all these products are elucidated by spectral (IR, H
NMR and MS) and analytical data, and are further sup-
ported by an X-ray crystallographic analysis of 3a
Table 1 Synthesis of Benzo[f]indole-4,9-diones 3 and Benzo[b]car-
bazoles 5, 7 and 8
(Figure 1). These reactions are proposed to proceed by
first attack of the Ca in 2 at one of the C(–Cl) atoms in 1,17
Reactants Solvent, base
Temp
(°C)
Time
(h)
Product (yield,
%)a
leading to the monoalkylated product followed by
intramolecular attack of the N atom in 1 at the second
C(–Cl) bond to give the products 3.28,29 It was noted that
enaminones with an aryl at the N atom (2a–e) gave better
yields of the dialkylation products (3a–e) than the enami-
nones with an alkyl at the N atom (2f). Control experi-
ments showed that the enaminone 2f and the product 3f
are stable on lengthy refluxing with sodium carbonate in
acetonitrile without significant decomposition. Therefore,
the reduced yield for 2f is probably caused by the higher
basicity and nucleophilicity of the enamine moiety in 2f
than in 2a–e, which may result in the competitive first
attack of the N atom at the C–Cl bond of 1 in the first stage
of the reaction to lead to II, which cannot be further
cyclized.
1, 2a
1, 2b
1, 2c
1, 2d
1, 2e
1, 2f
DMF, K2CO3
DMF, K2CO3
DMF, K2CO3
DMF, K2CO3
DMF, K2CO3
MeCN, K2CO3
MeCN, K2CO3
MeCN, K2CO3
MeCN, K2CO3
MeCN, K2CO3
MeCN, K2CO3
MeCN, K2CO3
80
6
6
3a (91)
75
3b (91)
80
6
3c (91)
80
8
3d (43)
80
8
3e (67)
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
8
3f (41)
1, 4a
1, 4b
1, 4c
1, 6a
1, 6ab
1, 6b
8
5a (75)
8
5b (83)
8
5c (60)
Reaction of 1 with the monoenamines of dimedone (4a–c)
similarly results in the one-pot synthesis of the corre-
sponding benzo[b]carbazoles 5 in 60–83% yields. How-
ever, in the reactions of 1 with the cyclohexadione
monoenamines 6a and 6b, 1,2,3,4-tetrahydro-5H-ben-
zo[b]carbazole-4,6,11-triones 7a,b were obtained togeth-
er with their dehydrogenated products 8a and 8b. Control
10
30
10
7a (50), 8a (7)
8a (52)
7b (60), 8b(6)
a Yield of isolated products.
b Reaction was conducted under an oxygen atmosphere.
Synlett 2006, No. 12, 1913–1917 © Thieme Stuttgart · New York

LETTER
Benzo[f]indole-4,9-dione and Benzo[b]carbazole-6,11-dione Derivatives
1915
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Figure 1 ORTEP drawing of 3a (No. CCDC 298875)
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experiments showed that the dehydrogenative aromatiza-
tions are effected by dissolving oxygen in the reaction so-
lution. Therefore, reaction of 1 with 6a in deoxygenated
solution under argon atmosphere gave 7a as the only
product in 52% yield without 8a formation. We have fur-
ther found that 7a can be transformed into 8a in 90% yield
by refluxing in oxygen-saturated MeCN solution. There-
fore, by conducting the reaction of 1 with the cyclohex-
anedione monoenamines under deaerated and aerated
conditions, respectively, selective preparations of the
hydrogenated benzo[b]carbazole-4,6,11-triones 7 or the
dehydro-aromatized
4-hydroxy
benzo[b]carbazole-
(9) (a) Rickards, R. W.; Rothschild, J. M.; Willis, A. C.; de
Chazal, N. M.; Kirk, J.; Kirk, K.; Saliba, K. J.; Smith, G. D.
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4,6,11-triones 8 can be achieved. This further increases
the synthetic versatility of this one-pot reaction of 1 with
the enaminones.
In summary, an efficient and direct one-pot synthesis of
benzo[f]indole-4,9-diones 3 and benzo[b]carbazole-6,11-
diones 5, 7 and 8 has been achieved by novel sequential
Ca- and N-dialkylations of a series of b-enaminones by
2,3-dichloronaphthoquinone 1 in the presence of the solid
base sodium carbonate in moderate to high yields. The
1,2,3,4-tetrahydro-5H-benzo[b]carbazole-4,6,11-triones
7 formed in the reactions of the cyclohexadione mono-
enamines 6 with 1 can be easily dehydrogenated to the
benzo[b]carbazole-6,11-diones.
(12) (a) Germeraad, P.; Moore, H. W. J. Chem. Soc., Chem.
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Acknowledgment
(13) Weeratunga, G.; Prasad, G. K. B.; Dilley, J.; Taylor, N. J.;
Dmitrienko, G. I. Tetrahedron Lett. 1990, 31, 5713.
(14) (a) Jiang, M.-C.; Chuang, C.-P. J. Org. Chem. 2000, 65,
5409. (b) Wu, Y.-L.; Chuang, C.-P.; Lin, P.-Y. Tetrahedron
2001, 57, 5543. (c) Tseng, C.-C.; Wu, Y.-L.; Chuang, C.-P.
Tetrahedron 2002, 58, 7625. (d) Tseng, C.-M.; Wu, Y.-L.;
Chuang, C.-P. Tetrahedron 2004, 60, 12249.
This work was supported by the National Natural Science Founda-
tion of China [NSFC 20272024]. Partial support from the Modern
Analytical Center at Nanjing University is also appreciated.
References and Notes
(15) (a) Kobayashi, K.; Takeuchi, H.; Seko, S.; Kanno, Y.;
Kujime, S.; Suginome, H. Helv. Chim. Acta 1993, 76, 2942.
(b) Kobayashi, K.; Takeuchi, H.; Seko, S.; Suginome, H.
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(16) Shakhnovich, A. I. J. Heterocycl. Chem. 1991, 28, 33.
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214358.
(1) (a) The Chemistry of Functional Groups: The Chemistry of
the Quinoid Compounds; Patai, S.; Rappoport, Z., Eds.;
Wiley: New York, 1988. (b) Thomson, R. H. Naturally
Occurring Quinones, 4th ed.; Chapman and Hall: London,
New York, 1997.
Synlett 2006, No. 12, 1913–1917 © Thieme Stuttgart · New York

1916
H.-Y. Hu et al.
LETTER
(18) (a) Knölker, H.-J.; O’Sullivan, N. Tetrahedron 1994, 50,
10893. (b) Knölker, H.-J.; O’Sullivan, N. Tetrahedron Lett.
1994, 35, 1695.
2837, 1665, 1589, 1515, 1495, 1459, 1430, 1281, 1246, 1212
cm–1. MS: m/z (%) = 359 [M+, base], 344 (87), 328 (16), 273
(15), 238 (7), 217 (6), 127 (8), 92 (9), 77 (14). Anal. Calcd
for C22H17NO4: C, 73.54; H, 4.74; N, 3.90. Found: C, 73.55;
H, 4.63; N, 4.00.
(19) (a) Liu, Y.; Gribble, G. W. Tetrahedron Lett. 2001, 42,
2949. (b) Bennasar, M.-L.; Roca, T.; Ferrando, F.
Tetrahedron Lett. 2004, 45, 5605. (c) Cruces, J.; Martinez,
E.; Treus, M.; Martinez, L. A.; Estévez, J. C.; Estévez, R. J.;
Castedo, L. Tetrahedron 2002, 58, 3015. (d) Miki, Y.;
Tsuzaki, Y.; Matzukida, H. Heterocycles 2002, 57, 1645.
(e) Rajeswaran, W. G.; Srinivasan, P. C. Synthesis 1994,
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Tetrahedron Lett. 1993, 34, 4713. (b) Echavarren, A. M.;
Tamayo, N.; de Frutos, Ó.; Garcia, A. Tetrahedron 1997,
53, 16835.
Compound 3c: yellow solid, mp 254–256 °C. 1H NMR (300
MHz, CDCl3): d = 2.22 (s, 3 H), 2.72 (s, 3 H), 2.81 (s, 3 H),
7.42 (d, 2 H, J = 8.4 Hz), 7.65–7.75 (m, 2 H), 8.00 (dd,
J = 7.5, 1.5 Hz), 8.18–8.20 (m, 3 H). 13C NMR (100 MHz,
CDCl3): d = 11.8, 26.8, 31.8, 123.0, 125.4, 126.3, 126.9,
127.7, 129.7, 131.0, 132.8, 133.4, 133.5, 133.6, 137.8,
140.8, 142.3, 175.0, 180.8, 196.7, 198.8. IR (KBr): n = 3349,
3321, 3091, 3063, 3032, 3003, 1686, 1670, 1651, 1602,
1589, 1525, 1498, 1426, 1356, 1281, 1267, 1246, 1212, 1116
cm–1. MS: m/z (%) = 371 [M+, base], 356 (85), 328 (14), 310
(11), 228 7), 171 (7), 127 (7), 76 (10). Anal. Calcd for
C23H17NO4: C, 74.39; H, 4.58; N, 3.77. Found: C, 74.46; H,
4.78; N, 3.77.
(21) Hu, H.-Y.; Zhu, Y.; Wang, L.; Xu, J.-H. Synthesis 2005,
1605.
Compound 5a: yellow solid, mp 259–260 °C. 1H NMR (300
MHz, CDCl3): d = 1.11 (s, 6 H), 2.48 (s, 2 H), 2.56 (s, 2 H),
7.33–7.36 (m, 2 H), 7.61–7.66 (m, 4 H), 7.71 (td, J = 7.4, 1.4
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Rappoport, Z., Ed.; Wiley: Chichester, 1994, Chap. 10, 523.
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1997, 67, 207. (d) Michael, J. P.; Konig, C. B. D.;
Gravestock, D.; Hoskens, G. D.; Howard, A. S.; Jungmann,
C. M.; Krause, R. W. W.; Parsons, A. S.; Pelly, S. C.;
Stanbery, T. V. Pure Appl. Chem. 1999, 71, 979. (e) Erian,
A. W. Chem. Rev. 1993, 93, 1991. (f) Elassar, A.-Z. A.; El-
Khair, A. A. Tetrahedron 2003, 59, 8463. (g) Stanovnik,
B.; Svete, J. Chem. Rev. 2004, 104, 2433.
Hz), 7.98 (dd, J = 7.5, 1.2 Hz), 8.27 (dd, J = 7.5, 1.3 Hz). 13
C
NMR (75 MHz, CDCl3): d = 28.7, 35.2, 36.9, 53.8, 118.5,
126.4, 127.3, 127.7, 130.1, 133.0, 133.4, 134.1, 134.3,
137.0, 151.4, 176.2, 179.5, 191.7. IR (KBr): n = 3320, 3085,
2959, 2934, 2871, 1682, 1668, 1591, 1497, 1467,
1284,1268, 1202 cm–1. MS: m/z (%) = 369 [M+], 313 (100),
312 (45), 285 (18), 77 (13). Anal. Calcd for C24H19NO3: C,
78.05; H, 5.15; N, 3.79. Found: C, 78.08; H, 5.25; N, 3.74.
Compound 5b: yellow solid, mp 258–260 °C. 1H NMR (300
MHz, CDCl3): d = 1.11 (s, 6 H), 2.49 (s, 2 H), 2.55 (s, 2 H),
3.93 (s, 3 H), 7.09 (d, 2 H, J = 8.8 Hz), 7.25 (d, 2 H, J = 8.8
Hz), 7.64 (td, 1 H, J = 7.4, 0.9 Hz), 7.71 (td, 1 H, J = 7.4, 1.0
(23) Allen, G. R. Org. React. 1973, 20, 337.
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(b) Rehn, S.; Bergman, J. Tetrahedron 2005, 61, 3115.
(25) Charushin, V. N.; Mochulskaya, N. N.; Andreiko, A. A.;
Filyakova, V. I.; Kodess, M. I.; Chupakhin, O. N.
Tetrahedron Lett. 2003, 44, 2421.
(26) (a) Savarin, C. G.; Murry, J. A.; Dormer, P. G. Org. Lett.
2002, 4, 2071. (b) Bashford, K. E.; Burton, M. B.; Cameron,
S.; Cooper, A. L.; Hogg, R. D.; Kane, P. D.; MacManus, D.
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(28) General Procedures for the Synthesis of 3.
A mixture of 1 (1.1 mmol), 2 (1 mmol) and Na2CO3 (2.5
mmol) in DMF (15 mL) was heated at 80 °C for 6 h with
magnetic stirring and TLC monitoring of the reaction, the
solvent was removed under reduced pressure, and the
residual solid was separated by flash chromatography on a
silica gel column with PE (bp 60–90 °C)–EtOAc as eluent to
give the product.
General Procedures for the Synthesis of 7 and 8.
A mixture of 1 (1.1 mmol), 6 (1 mmol) and Na2CO3 (2.5
mmol) in MeCN (15 mL) was heated under reflux for 8 h.
The reaction mixture was poured into H2O and the pH of the
aqueous solution was adjusted to 5 by adding aq HCl. Work-
up of the residual solid as above gave the products.
(29) Analytical and Spectroscopic Data of New Compounds
Prepared.
Hz), 7.98 (d, 1 H, J = 7.5 Hz), 8.25 (d, 1 H, J = 7.2 Hz). 13
C
NMR (100 MHz, CDCl3): d = 28.3, 34.7, 36.6, 53.4, 55.6,
114.8, 117.9, 125.0, 126.0, 127.2, 128.0, 129.1, 132.6,
133.0, 133.6, 133.7, 133.9, 151.4, 160.3, 175.9, 179.2,
191.4. IR (KBr): n = 3317, 3064, 3011, 2955, 2935, 2896,
2868, 2838, 1686, 1660, 1608, 1588, 1514, 1497, 1469,
1304, 1283, 1268, 1251, 1202, 1172 cm–1. MS: m/z (%) =
399 [M+], 343 (100), 300(9), 105 7), 85 (7), 77 (7), 55 (9), 44
(82). Anal. Calcd for C25H21NO4: C, 75.19; H, 5.26; N, 3.51.
Found: C, 75.24; H, 5.32; N, 3.30.
Compound 5c: yellow solid, mp 268–269 °C. 1H NMR (300
MHz, CDCl3): d = 1.10 (s, 6 H), 2.47 (s, 2 H), 2.53 (s, 2 H),
7.32 (d, 2 H, J = 8.6 Hz), 7.58 (d, 2 H, J = 8.6 Hz), 7.63 (dd,
1 H, J = 7.5, 1.4 Hz), 7.69 (td, 1 H, J = 7.5, 1.3 Hz), 7.93 (dd,
1 H, J = 7.5, 1.3 Hz), 8.21 (dd, 1 H, J = 7.6, 1.2 Hz). 13
C
NMR (100 MHz, CDCl3): d = 28.3, 34.8, 36.6, 53.3, 118.3,
125.2, 126.0, 127.3, 128.3, 130.0, 132.4, 133.1, 133.6,
133.8, 133.9, 135.0, 135.9, 150.8, 175.9, 179.0, 191.2. IR
(KBr): n = 3306, 3112, 3091, 3060, 3043, 2956, 2928, 2896,
2870, 1684, 1660, 1591, 1496, 1465, 1421, 1300, 1283,
1266, 1202 cm–1. MS: m/z (%) = 405 [M + 2], 403 [M+], 388
(10), 347 (100), 319 (15), 284 (11), 126 (10). Anal. Calcd for
C24H18ClNO3: C, 71.38; H, 4.46; N, 3.47. Found: C, 71.40;
H, 4.56; N, 3.56.
Compound 7a: yellow solid, mp 269–271 °C. 1H NMR (300
HMz, CDCl3): d = 2.16 (quint, 2 H, J = 6.2 Hz), 2.61–2.70
(m, 4 H), 7.36–7.39 (m, 2 H), 7.60–7.65 (m, 4 H), 7.70 (td,
1 H, J = 7.4, 1.3 Hz), 7.96 (dd, 1 H, J = 7.5, 1.2 Hz), 8.24
(dd, 1 H, J = 7.7, 1.2 Hz). 13C NMR (100 MHz, CDCl3):
d = 22.6, 22.8, 39.4, 119.0, 125.2, 125.9, 126.9, 127.2,
129.6, 129.7, 132.5, 132.9, 133.3, 133.7, 133.9, 136.6,
152.1, 175.8, 179.1, 191.7. IR (KBr): n = 3309, 3048, 2952,
2872, 1684, 1661, 1593, 1496, 1470, 1278, 1208 cm–1. MS:
m/z (%) = 341 [M+], 339 (100), 313 (78), 285 (15), 254 (16),
Compound 3b: yellow solid, mp 209–210 °C. 1H NMR (300
MHz, CDCl3): d = 2.21 (s, 3 H), 2.81 (s, 3 H), 3.92 (s, 3 H),
7.08 (d, 2 H, J = 8.8 Hz), 7.21 (d, 2 H, J = 8.8 Hz), 7.64–7.74
(m, 2 H), 8.02 (dd, 1 H, J = 7.1, 1.6 Hz), 8.19 (dd, 1 H,
J = 7.1, 1.4 Hz). 13C NMR (75 MHz, CDCl3): d = 12.2, 32.2,
55.9, 115.1, 122.9, 125.5, 126.6, 127.1, 128.5, 129.8, 131.5,
133.5, 133.6, 133.7, 134.0, 143.4, 160.6, 175.4, 181.3,
199.4. IR (KBr): n = 3302, 3096, 3066, 3005, 2962, 2934,
Synlett 2006, No. 12, 1913–1917 © Thieme Stuttgart · New York

LETTER
Benzo[f]indole-4,9-dione and Benzo[b]carbazole-6,11-dione Derivatives
1917
228 (18), 180 (10), 152 (28), 126 (26), 105 (25), 77 (88).
Anal. Calcd for C22H15NO3: C, 77.42; H, 4.40; N, 4.11.
125.3, 125.4, 126.0, 127.1, 127.4, 128.2, 128.8, 129.9,
130.3, 132.4, 132.9, 133.3, 133.7, 134.1, 134.3, 152.8,
Found: C, 77.27; H, 4.34; N, 4.21.
175.7, 179.2, 191.7. IR (KBr): n = 3376, 3057, 2952, 1686,
1666, 1593, 1496, 1474, 1282 cm–1. MS: m/z (%) = 391
[M+], 363 (79), 334 (13), 278 (11), 95 (12), 69 (16), 43 (80).
Anal. Calcd for C26H17NO3: C, 79.80; H, 4.35; N, 3.58.
Found: C, 79.82; H, 4.36; N, 3.57.
Compound 8a: red solid, mp >300 °C. 1H NMR (300 MHz,
CDCl3): d = 6.63 (d, 1 H, J = 8.5 Hz), 6.85 (d, 1 H, J = 7.9
Hz), 7.33 (t, 1 H, J = 8.2 Hz), 7.45 (t, 2 H, J = 4.0 Hz), 7.62–
7.63 (m, 3 H), 7.75 (quint, 2 H, J = 6.9 Hz), 8.07 (d, 1 H,
J = 7.1 Hz), 8.28 (d, 1 H, J = 6.9 Hz). 13C NMR (CDCl3):
d = 103.3, 109.2, 114.7, 121.2, 127.3, 127.4, 127.8, 129.8,
130.0, 130.8, 133.2, 133.9, 134.2, 134.4, 137.0, 143.2,
153.3, 176.9, 183.8. IR (KBr): n = 3043, 1668, 1620, 1589,
1578, 1495, 1430, 1270 cm–1. MS: m/z (%) = 339 (100)
[M+], 310 (14), 254 (11), 151 (7), 77 (11). Anal. Calcd for
C22H13NO3: C, 77.88; H, 3.83; N, 4.13. Found: C, 77.82; H,
3.75; N, 4.16.
Compound 8b: red solid, mp 270–272 °C (dec.). 1H NMR
(300 MHz, CDCl3): d = 6.40 (d, 1 H, J = 8.3 Hz), 6.86 (d, 1
H, J = 7.8 Hz), 7.17 (d, 1 H, J = 8.5 Hz), 7.23–7.32 (m, 1 H),
7.40 (t, 1 H, J = 7.6 Hz), 7.54–7.64 (m, 2 H), 7.66–7.79 (m,
3 H), 7.94 (d, 1 H, J = 7.4 Hz), 8.04 (d, 1 H, J = 8.3 Hz), 8.13
(d, 1 H, J = 8.3 Hz), 8.31 (d, 1 H, J = 7.1 Hz), 10.90 (s, 1 H).
13C NMR (100 MHz, CDCl3): d = 103.1, 108.9, 114.4,
121.9, 125.4, 125.5, 126.9, 127.0, 127.6, 128.6, 130.1,
130.2, 130.5, 133.0, 133.3, 133.4, 133.8, 134.0, 134.4,
135.8, 143.3, 153.0, 176.2, 183.5. IR (KBr): n = 3300, 3134,
3054, 2952, 1664, 1629, 1618, 1586, 1499, 1400, 1270, 1221
cm–1. MS: m/z (%) = 389 [M+], 373 (11), 105 (10), 77 (13).
Anal. Calcd for C26H15NO3: C, 80.21; H, 3.86; N, 3.60.
Found: C, 80.15; H, 3.91; N, 3.78.
Compound 7b: yellow solid, mp 265–266 °C (dec.). 1H
NMR (300 MHz, CDCl3): d = 2.09–2.19 (m, 2 H), 2.37 (dt,
1 H, J = 17.4, 5.4 Hz), 2.63 (d, J = 17.2 Hz), 2.72 (t, 2 H,
J = 6.3 Hz), 7.17 (d, 1 H, J = 8.3 Hz), 7.48–7.74 (m, 6 H),
7.88 (d, 1 H, J = 7.6 Hz), 8.04 (d, 1 H, J = 8.1 Hz), 8.12 (d,
1 H, J = 8.3 Hz), 8.30 (d, 1 H, J = 7.6 Hz). 13C NMR (100
MHz, CDCl3): d = 22.2, 22.6, 39.4, 119.2, 121.2, 124.9,
Synlett 2006, No. 12, 1913–1917 © Thieme Stuttgart · New York