Reaction of methyl-3-nitroacrylate with 3-(2-nitroethenyl)indole

Full text of DOI:10.1134/S1070428006080288

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2006, Vol. 42, No. 8, pp. 1246-1247. Ó Pleiades Publishing, Inc. 2006.
Original Russian Text Ó N.A. Anisimova, G.A. Berkova, V.V. Ladygin, V.M. Berestovitskaya, 2006, published in Zhurnal Organicheskoi
Khimii, 2006, Vol. 42, No. 8, pp. 1263-1264.
SHORT
COMMUNICATIONS
Reaction of Methyl-3-nitroacrylate with 3-(2-Nitroethenyl)indole
N.A.Anisimova, G.A. Berkova, V.V. Ladygin, and V.M. Berestovitskaya
Herzen Russian Pedagogical University, St. Petersburg, 191186 Russia, e-mail: kohrgpu@yandex.ru
Received January 24, 2006
DOI: 10.1134/S1070428006080288
two paths and led to the formation of regioisomeric tetra-
hydrocarbazoles Ia and Ib which already under the reac-
tion conditions suffered an intramolecular transformation
Carbazole is a structural fragment of many substances
possessing useful properties [1]. This heterocycle attracts
interest because it is widespread in the nature (being the
key structural element of the carbazole alkaloids [2]) and
is relatively easily available (being one of the components
of coal-tar pitch [3]).
(
dehydration and denitration) into the corresponding
carbazolylcarboxylates possessing a nitro group IIa and
IIb or free of the nitro group IIIa and IIIb.
Applying the column chromatography we not only
succeeded in isolation compounds Ia, Ib–IIIa, IIIb as
mixtures of regioisomeric pairs, but we were also able to
identify regioisomers IIb and IIIa as individual substances.
It is known that a- and b-nitrovinylindoles react with
dienophiles (maleic anhydride, ethyl acrylate, acrylonitrile,
cinnamic aldehyde) to form the corresponding substituted
carbazoles [4, 5].
In order to prepare functionalized nitrocarbazoles we
investigated for the first time a [4+2]-cycloaddition of
methyl 3-nitroacrylate (dienophile) and 3-(2-nitroethenyl)-
indole (diene). The reaction was carried out by boiling
the reagents mixture in toluene in the presence of
aluminum chloride for 2 h. The process proceeded along
The structure of compounds Ia, Ib–IIIa, IIIb obtained
was established by IR and H NMR spectroscopy in
1
comparison with the spectra of structurally similar
compounds described in [6, 7]. The formation of regio-
isomeric pairs of these compounds follows from the
1
appearance in the H NMR spectrum of a double set of
+
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2 0H
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+ 12
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B
B
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1246

REACTION OF METHYL-3-NITROACRYLATE WITH 3-(2-NITROETHENYL)INDOLE
1247
signals from protons of the substituted ring, and from the
ester group protons.
(eluent benzene), ratio IIa:IIb = 1:10, R 0.49, 0.40, mp 133–
f
135°S, isomer IIb (eluent at repeated chromatography
–1
benzene) mp 153–155°C. IR spectrum, cm : 1730 (S=O),
The assignment of the regioisomer structure of
compounds Ia, Ib–IIIa, IIIb obtained was done basing
on the different effect of the substituents on the ring
protons in the compared structures using as an analytical
criterion the difference in the chemical shifts and the
integral intensities of methylene, methine (for compounds
Ia and Ib), and aromatic (for compounds IIa, IIb and
IIIa, IIIb ) protons, and also the coupling constants
1
1
330, 1520 (NO ), 3460 (NH). H NMR spectrum, d, ppm:
2
isomer IIa, 3.90 s (3H, CN ), 7.25–7.65 m (4H, C H ),
.90 d [1H, C H, J 7.5 Hz], 8.15 d (1H, C H,
3
6
4
4
3
7
3,4
J 7.5 Hz), 10.50 (1H, NH); isomer IIb, 4.03 s (3H, CH ),
3,4
3
4
7
8
.25–7.65 m (4H, C H ), 8.15 d (1H, C H, J 8.0 Hz),
.35 d [1N, C H, J 8.0 Hz], 10.00 (1H, NH). Found,
6 4 3,4
3
3,4
%
: C 61.72, 61.77; H 3.30, 3.44; N 9.81, 9.82.
1
C H N O . Calculated, %: C 62.22; H 3.70; N 10.37.
values. For instance, in the H NMR spectrum of the
14 10
2
4
mixture of compounds Ia and Ib the more downfield
2-Methoxycarbonyl- and 1-methoxycarbonyl-
carbazoles (IIIa and IIIb). Yield 25% (eluent benzene),
ratio IIIa:IIIb = 10:1, mp 165–168°C, isomer (IIIa)
(eluent at repeated chromatography benzene) mp 171–
nitromethine protons at 4.30 and 4.35 ppm attached to
2
3
atoms C , C were assigned to isomer Ib on the strength
of the greater deshielding effect of the nitro groups
compared to that (4.20 and 4.25 ppm) for the protons at
–
1
173°C. IR spectrum, cm : 1710 (C=O), 3465 (NH).
1
3
1
C , C in Ia isomer..
H NMR spectrum, d, ppm: isomer IIIa, 4.20 s (3N,
CN ), 7.20–7.60 m (4H, C H ), 7.80 (1H, NH), 7.90–
8
Based on the coupling constants of the vicinal protons
3
6
4
3
4
1
.10 m (2H ,C H ,C H), 8.30 s (1H, C H); isomer IIIb,
equal to 7.5–8.0 Hz we ascribed the ortho-orientaion of
3
4
3.90 s (3H, CH ), 7.20–7.60 m (4N, C H ), 7.90 d.d (1H,
aromatic protons at atoms C , C in carbazole regioisomers
IIa and IIb [4, 8]. The effect of the nitro group caused
a downfield shift of the resonances of aromatic protons
3
6
4
3
4
C H, J 9.0, J3,2 0.8 Hz), 8.10 d.d (1H, C H, J 9.0,
J2,4 0.8 Hz), 8.15 d.d (1H, C H, J 7.9, J2,4 1.1 Hz),
3,4
3,4
2
2,3
3
4
8.70 (1H, NH). Found, %: C 74.27, 74.24; H 4.95, 4.97;
H , H in carbazole IIb to 8.15 and 8.35 ppm, whereas in
isomer IIa they appear in a stronger field, at 7.90 and
N 6.92, 6.93. C H NO . Calculated, %: C 74.66;
14 11
2
1
H 4.89; N 6.63.
8
.15 ppm respectively. In the H NMR spectrum of regio-
1
isomer IIIa the aromatic proton at C gives rise to a
IR spectra were recorded on a spectrophotometer
Infra-LYuM FT-02 from solutions in chloroform, c 0.1–
0.001 mol l-1. 1N NMR spectra were registered on
a spectrometer Bruker AS-200 (200 MHz) in
deuterochloroform, external reference HMDS.
3
4
singlet at 8.30 ppm, and the signals of protons H , H are
observed as a multiplet in the region 7.90–8.10 ppm. The
signals of the aromatic protons of regioisomer IIIb at
the atoms C , C , C appear in the range 7.90–8.15 ppm,
with the coupling constant of the ortho-protons H , H
2
3
4
3
4
2
4
9
.0 Hz, of meta-protons H , H 0.8–1.1 Hz.
REFERENCES
The initial methyl 3-nitroacrylate was prepared by the
procudure from [9] refined by us, the synthesis of 3-(2-
nitroethenyl)indole was performed by method [10].
1
. Filimonov, V.D. and Sirotkina, E.E., Khimiya monomerov na
osnove karbazola (Chemistry of Monomers on the Basis
of Carbazole), Novosibirsk: Nauka, 1995, p. 533.
2. Narsimhan, N.S. and Gokhale, S.M., Chem. Commun., 1985,
p. 86.
2
-Methoxycarbonyl-1,3-dinitro- and 1-methoxy-
carbonyl-2,3-dinitro-1,2,3,4-tetrahydrocarbazoles
Ia and Ib). Yield 34% (eluent acetone), R 0.40,
3. Heterocyclic Compounds, Elderfield, R.C., Ed., New York:
(
0
f
Wiley, 1957, vol. 3.
.45, mp 108–110°C, ratio Ia:Ib = 3:2. IR spec-
4. Narasimhan, N.S. and Kusurkar, R.S., Ind. J. Chem., 1983,
–
1
trum (CHCl ), cm : 1730 (S=O), 1328, 1536 (NO ), 3460
3
2
vol. 22B, p. 846.
1
(
NH). H NMR spectrum, d, ppm: isomer Ia, 2.20–
.50 m (2H, C H, J3 16.5 Hz), 3.50 m (1H, C H),
.90 s (3H, CH ), 4.20 m (1N, C H), 4.25 (1H, C H),
5. Kusurkar, R.S. and Patil, U.G., Ind. J. Chem., 1986, vol. 25B,
4
2
2
3
7
2
3
7
1
,4
p. 1038.
3
1
3
6. Clancy, V.G., Hesabi, M.M., and Meth-Cohn, O., Chem.
Commun., 1980, p. 1112.
7. Moody, C.J. and Rahimtoola, K.F., J. Chem. Soc., Perkin
.20–7.60 m (4H, C H ), 10.20 (1H, NH); isomer Ib,
6
4
4
1
.20–2.50 m (1H, S H, J3,4 16.5 Hz), 3.30 m (1H, C H),
.80 s (3H, CN ), 4.30 m (1N, C H), 4.35 m (1N, C H),
3
2
Trans. 1, 1988, p. 1407.
3
8. Sergeev, N.M., Spektroskopiya YaMR (NMR Spectros-
.20–7.60 m (4H, C H ), 9.50 (1H, NH). Found, %: H
6
4
copy), Moscow: Izd. Moskovskii Gos. Univ., 1981, p. 89.
3.35, 13.39. C H N O . Calculated, %: N 13.17.
1
4
13
3
6
9. Shechter, H. and Conrad, F., J. Am. Chem. Soc., 1953, vol. 75,
2
-Methoxycarbonyl-1-nitro- and 1-methoxy-
p. 5610.
carbonyl-2-nitrocarbazoles (IIa and IIb). Yield 8%
10. Jong, E., J. Chem. Soc., 1958, p. 3493.
RUSSIAN JOURNALOF ORGANIC CHEMISTRYVol. 42 No. 8 2006