Synthesis of 7-bromo, 7-phenylethynyl, 7-azido, and 7-nitro derivatives of N-acetyl-1,3a,4,8b-tetrahydrocyclopenta[b]indole

Article abstract of DOI:10.1134/S1070428014010096

7-Bromo-, 7-phenylethynyl-, 7-azido-, 7-nitro-, and 5,7-dinitro-substituted N-acetyl-1,3a,4,8b-tetrahydrocyclopenta[b]indoles have been synthesized starting from anilines and 3-chlorocyclopentene. The NMR spectra of N-acetyl-7-nitro-1,3a,4,8b-tetrahydrocyclopenta[b]indoles displayed no signal doubling typical of the other 7-substituted derivatives.

Full text of DOI:10.1134/S1070428014010096

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2014, Vol. 50, No. 1, pp. 48–53. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © D.A. Skladchikov, A.A. Fatykhov, R.R. Gataullin, 2014, published in Zhurnal Organicheskoi Khimii, 2014, Vol. 50, No. 1,
pp. 55–60.
Synthesis of 7-Bromo, 7-Phenylethynyl, 7-Azido, and 7-Nitro
Derivatives of N-Acetyl-1,3a,4,8b-tetrahydrocyclopenta[b]indole
D. A. Skladchikov, A. A. Fatykhov, and R. R. Gataullin
Institute of Organic Chemistry, Ufa Research Center, Russian Academy of Sciences,
pr. Oktyabrya 71, Ufa, 450054 Bashkortostan, Russia
e-mail: gataullin@anrb.ru
Received July 31, 2013
Abstract—7-Bromo-, 7-phenylethynyl-, 7-azido-, 7-nitro-, and 5,7-dinitro-substituted N-acetyl-1,3a,4,8b-tetra-
hydrocyclopenta[b]indoles have been synthesized starting from anilines and 3-chlorocyclopentene. The NMR
spectra of N-acetyl-7-nitro-1,3a,4,8b-tetrahydrocyclopenta[b]indoles displayed no signal doubling typical of the
other 7-substituted derivatives.
DOI: 10.1134/S1070428014010096
Cyclopenta[b]indole derivatives with different
substituents on C7 are used in photochemical studies
[1–5]; they also modulate activity of some receptors
[6, 7]. In this work we made an attempt to introduce
phenylethynyl and azido groups into the 7-position of
cyclopenta[b]indole. The resulting compounds could
be used in “click” chemistry reactions for the prepara-
tion of triazole derivatives. We tried to attach a phenyl-
ethynyl group to C7 through 7-bromo derivative. For
this purpose, aniline (Ia) and 4-bromoaniline (Ib) were
brought into transformations according to Scheme 1 to
obtain N-acetyl-1,3a,4,8b-tetrahydrocyclopenta[b]in-
dole (VIa) [8] and its 7-bromo-substituted analog VIb.
The bromination of VIa with N-bromosuccinimide was
not complete, and 7-bromo derivative VIb was formed
in 60% yield. To introduce a halogen atom, we also
examined the reaction of VIa with tetrabutylam-
monium tribromide [9], taking into account the
efficiency of this procedure in the bromination of
N-acylaniline [10]. However, the reaction involved the
double bond in the cyclopentene fragment with forma-
tion of stereoisomeric 2,3-dibromo derivatives which
were characterized by similar Rf values, so that we
failed to separate them by chromatography.
chloroform. 7-Nitro compound VIII was isolated from
the mother liquor by chromatography. Therefore, azide
IX was obtained by reaction of 7-bromo derivative VIb
with sodium azide (Scheme 2) under the conditions
described in [11], i.e., by heating in the presence of
CuI, L-proline, and NaOH in aqueous methanol. The
reaction required a long time, and the conversion of
VIb was incomplete. We failed to synthesize 7-amino
derivative X according to the procedure reported in
[12] by reaction of bromide VIb with ammonia in the
presence of CuI iodide and L-proline; after prolonged
heating at 50°C, the initial compound was recovered
from the reaction mixture. Compound XI possessing
a phenylethynyl group on C7 was synthesized by
alkynylation of bromo derivative VIb with phenyl-
acetylene according to [13]; this procedure was used
by us previously to obtain nucleoside derivatives.
The structure of the newly synthesized compounds
was determined by spectral methods. The nitro groups
in molecule VII occupy meta positions with respect to
1
each other, as follows from the H NMR spectrum
which contains two downfield one-proton singlets in
the aromatic region at δ 8.45 and 8.50 ppm. Compound
1
VIII displayed in the H NMR spectrum two doublets
due to 5-H and 6-H and a singlet from 8-H, indicating
that the nitro group is attached to C7. The 5-H proton is
also involved in long-range couplings with small
constants of 0.7 to 2.4 Hz (Figs. 1, 2).
In the 1H NMR spectra of IX and XI, the 5-H signal
is displaced downfield (δ 8.17 ppm), whereas the cor-
Our endeavor to introduce an azide group into the
7-position of cyclopenta[b]indole through 7-nitro
derivative was unsuccessful. Compound VIa reacted
with trifluoroacetyl nitrate under mild conditions to
give a mixture of products from which we isolated
5,7-dinitro derivative VII by crystallization from
48

SYNTHESIS OF 7-BROMO, 7-PHENYLETHYNYL, 7-AZIDO, AND 7-NITRO
49
Scheme 1.
NH2
NH2
145°C, 4 h
+
Cl
Ia
IIIa
NH2
H
N
NH2
Et3N, 80°C, 2 h
HCl, xylene, reflux, 6 h
+
Cl
H
X
X
X
Ia, Ib
IIa, IIb
IIIa, IIIb
H
H
I2, NaHCO3
CH2Cl2
Piperidine
reflux, 5 h
X
X
X
Ac2O, CH2Cl2
I
I
N
N
N
H
H
H
H
Ac
Ac
IVa, IVb
Va, Vb
VIa, VIb
H
H
8
5
O2N
O2N
NH4NO3, (F3CCO)2O
CH2Cl2, –30°C
NBS, CH2Cl2, 20°C
+
6
VIa
VIb
N
N
H
H
Ac
Ac
NO2
VII
VIII
X = H (a), Br (b).
Scheme 2.
H
N3
NaN3, CuI, L-proline, NaOH
MeOH, 80°C, 48 h
N
H
H
Ac
IX (syn, anti)
Br
Ph
Ph
N
H
H
H
Ac
VIb (syn, anti)
HC≡CPh, CuI, Pd/C, Et3N
MeCN, 80°C, 12 h
+
N
N
H
H
O
Me
Me
O
XI (anti)
XI (syn)
H
NH3, CuI, L-proline, K2CO3
DMSO, 50°C, 36 h
H2N
VIb
IX
N
H
Ac
responding signal of VIb is observed at δ 8.08 ppm.
Replacement of the bromine atom in VIb by a phenyl-
ethynyl or azide group almost does not affect the posi-
tion of signals from protons on the double bond and
methylene group in the cyclopentene fragment, while
the 3a-H and 8b-H signals of XI are located slightly
downfield (Δδ 0.03 and 0.02 ppm, respectively) rela-
tive to the corresponding signals of bromo derivative
VIb. The phenylethynyl group induces a downfield
shift of the methyl proton signal from the N-acetyl
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 50 No. 1 2014

SKLADCHIKOV et al.
50
26.72
96.39
5.4
100.07
4.1
33.20
6.0
5.0
δ, ppm
Fig. 1. A fragment of the 1H NMR spectrum of compound VIa (CDCl3) corresponding to the 8b-H, 3a-H, 2-H, and 3-H signals.
191.84
6.0
99.81
5.7
99.50
4.2 δ, ppm
5.0
Fig. 2. A fragment of the 1H NMR spectrum of compound VIII (acetone-d6) corresponding to the 8b-H, 3a-H, 2-H, and 3-H signals.
group (Δδ 0.02 ppm) in the major syn isomer. The
acetyl proton signal of the minor anti isomer of XI
undergoes a stronger downfield shift (Δδ 0.04 ppm) as
compared to the minor isomer of VIb.
With a view to elucidate configuration of the
partially double C–N bond, NOE experiments were
carried out. Saturation at the 3a-H resonance frequency
produced a 2.5% increase in the CH3 signal intensity.
Saturation of the methyl proton signal gave NOEs on
3a-H (1.2%) and 3-H (0.8%). The intensity of the CH3
signal increased by 1.5% on saturation of the 3-H res-
onance. No NOE was observed between 5-H and
methyl protons. Presumably, the formation of partially
double C–N bond in molecule VIII is possible, but,
unlike 7-unsubstituted analogs, the syn–anti equilib-
rium is displaced almost completely toward the isomer
in which the CH3 group and C3a atom are oriented syn
with respect to the C=N bond. An additional factor
The presence of an electron-withdrawing nitro
group in the aromatic ring of VIII eliminates doubling
1
of some signals, which is typical of the H NMR
spectra of initial compound VIa and its 7-methyl
[14, 15], 7-azido, and 7-phenylethynyl derivatives. In
the spectrum of 7-bromo derivative VIb, where the
bromine atom exerts +M and –I effects, signals from
some protons were also split at a ratio of 5:1.
Partially double character of the bond between
the acetyl carbonyl carbon atom and nitrogen atom
[16, 17] in N-acetyltetrahydrocyclopenta[b]indole
derivatives may be determined by several factors. No
signal doubling is observed if an electron-donating or
electron-withdrawing substituent (NO2, Me, OMe,
NH2 [14, 15]) is present in the 5-position or electron-
withdrawing nitro group is attached to C7 while the
5-position is not occupied.
H
H
O2N
O2N
N
N
H
H
Me
O
H
O
Me
VIII (syn)
VIII (anti)
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 50 No. 1 2014

SYNTHESIS OF 7-BROMO, 7-PHENYLETHYNYL, 7-AZIDO, AND 7-NITRO
51
favoring syn orientation of the methyl group is en-
hancement of the intramolecular hydrogen bonding be-
tween 5-H and carbonyl oxygen atom due to electron-
withdrawing effect of the 7-nitro group, which makes
the 5-H proton more acidic.
was distilled in a vacuum. Yield 49 g (69%), bp 145–
150°C (3 mm). IR spectrum: ν 3406 cm–1 (NH).
4-Bromo-2-(cyclopent-2-en-1-yl)aniline (IIIb).
A solution of 24 g (0.1 mol) of compound IIb in
70 mL of xylene was saturated with excess gaseous
hydrogen chloride. The mixture was heated for 10 h
under reflux, cooled, and treated with a solution of 5 g
(0.125 mol) of sodium hydroxide in 25 mL of water,
and the organic phase was separated, dried over KOH,
and distilled under reduced pressure to isolate 4.13 g
(24%) of 4-bromoaniline and 15 g (65%) of compound
IIIb as a yellowish liquid, bp 130°C (2 mm). IR spec-
In summary, 7-bromo-, 7-(phenylethynyl)-, and
7-azido-N-acetyl-1,3a,4,8b-tetrahydrocyclopenta[b]in-
doles have been synthesized starting from p-bromo-
aniline. The nitration of N-acetyl-1,3a,4,8b-tetrahydro-
cyclopenta[b]indole gives a mixture of 7-nitro- and
5,7-dinitro derivatives. Amide conjugation in the
N-acetyl group of 7-bromo, 7-phenylethynyl, and
7-azido derivatives gives rise to syn/anti isomerism
which is reflected in doubling of some signals in the
NMR spectra. The presence of a nitro group in position
7 stabilizes the syn isomer, so that no signal doubling
is observed.
1
trum, ν, cm–1: 3383, 3469 (NH2). H NMR spectrum
(CDCl3), δ, ppm: 1.72–1.82 m (1H, 5′-H), 2.32–2.52 m
(3H, 4′-H, 5′-H), 3.66 br.s (2H, NH2), 3.80–3.82 m
(1H, 1′-H), 5.80–5.82 m (1H, 2′-H), 6.00–6.02 m (1H,
3′-H), 6.50 d.d (1H, 5-H, J = 1.3, 8.6 Hz), 7.03 s (1H,
3-H), 7.09 d.d (1H, 6-H, J = 1.3, 8.6 Hz). 13C NMR
spectrum (CDCl3), δC, ppm: 30.29 and 32.49 (C4′, C5′),
46.89 (C1′), 110.47 (C4), 117.27 (C6); 129.69, 130.39,
132.59, 133.34 (C3, C5, C2′, C3′); 131.68 (C2), 143.16
(C1). Found, %: C 55.36; H 5.01; Br 33.44; N 5.79.
C11H12BrN. Calculated, %: C 55.48; H 5.08; Br 33.56;
N 5.88.
EXPERIMENTAL
The IR spectra were recorded on a Shimadzu IR
Presstige-21 spectrometer with Fourier transform. The
1H and 13C NMR spectra were measured on a Bruker
1
AM 300 (300.13 and 75.45 MHz for H and 13C,
respectively) and Bruker Avance III 500 instruments
(500.13 and 125.73 MHz) using tetramethylsilane as
internal reference. The elemental compositions were
determined on a EURO EA-3000 CHNS Elemental
Analyzer. The mass spectra (atmospheric pressure
chemical ionization) were obtained on a Shimadzu
LCMS-2010EV instrument (eluent methanol–water,
1:1). The purity of liquid products was checked by
GLC on a Khromos GKh-1000 chromatograph
equipped with a flame-ionization detector and a 1-m×
3-mm column packed with 5% SE30 on Chromaton
N-AW; carrier gas helium. Qualitative TLC analyses
were carried out on Sorbfil PTSKh-AF-V-UF plates
(Sorbpolimer, Krasnodar, Russia); spots were detected
under UV light (λ 254 nm) and by treatment with
iodine vapor.
1-[(3R*,3aR*,8bS*)-7-Bromo-3-iodo-1,2,3,3a,4,8b-
hexahydrocyclopenta[b]indol-4-yl]ethanone (Vb).
Compound IIIb, 6.3 g (26 mmol), was dissolved in
60 mL of chloroform, 7 g of sodium hydrogen car-
bonate and 7 g of iodine were added, and the mixture
was stirred for 5 h, the progress of the reaction being
monitored by TLC. When the reaction was complete,
the mixture was diluted with 50 mL of chloroform,
treated with a 5% solution of Na2S2O3 (3×100 mL),
and washed with water (100 mL). The organic phase
was dried over MgSO4, and the solvent was removed
under reduced pressure. Yield of crude product IVb
9.1 g (25 mmol), Rf 0.76 (benzene). 1H NMR spectrum
(CDCl3), δ, ppm: 1.78–2.59 m (2H, CH2), 3.91 t (1H,
8b-H, J = 8.7 Hz), 4.09 br.s (1H, NH), 4.19 s (1H,
3-H), 4.75 d (1H, 3a-H, J = 8.7 Hz), 6.35 d (1H, 5-H,
J = 8.3 Hz), 7.05 d.d (1H, 6-H, J = 2.0, 8.3 Hz), 7.13 d
(1H, 8-H, J = 2.0 Hz).
4-Bromo-N-(cyclopent-2-en-1-yl)aniline (IIb).
Excess 3-chlorocyclopentene was added under stirring
to a solution of 51.6 g (0.3 mol) of 4-bromoaniline in
200 mL of triethylamine. The mixture was heated for
2 h at 90°C on a water bath, cooled to room tempera-
ture, and treated with a solution of 20 g (0.5 mol) of
sodium hydroxide in 80 mL of water. The mixture was
stirred, the organic layer was separated, dried over
KOH, separated from the drying agent by decanting,
and evaporated under reduced pressure, and the residue
Compound IVb, 8.3 g (23 mmol), was dissolved in
40 mL of methylene chloride, 14 g of potassium car-
bonate was added, and 3.2 g (26 mmol) of acetyl
bromide was added dropwise under stirring. When the
reaction was complete (TLC), the mixture was washed
with 50 mL of water and extracted with 50 mL of
methylene chloride. The extract was dried over MgSO4
and evaporated under reduced pressure, and the residue
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 50 No. 1 2014

SKLADCHIKOV et al.
52
was purified by chromatography on silica gel using
benzene as eluent. Yield of Vb 5 g (49% calculated on
IIIb). Gray needles, mp 133–134°C (from EtOH).
1H NMR spectrum (CDCl3), δ, ppm: 1.62–1.73 m (1H,
2-H), 2.05–2.15 m (2H, 1-H, 2-H), 2.34 s (3H, CH3),
2.58–2.69 m (1H, 1-H), 4.03 t (1H, 8b-H, J = 8.0 Hz),
4.41 d (1H, 3-H, J = 5.3 Hz), 5.10 d (1H, 3a-H, J =
8.0 Hz), 7.27—7.31 m (2H, 6-H, 8-H), 7.99 d (1H,
5-H). 13C NMR spectrum (CDCl3), δC, ppm: 23.97
(CH3), 29.93 and 35.65 (C1, C2), 23.29 (C3), 45.06
(C8b), 75.89 (C3a), 116.65 (C7), 117.83 (C5), 127.03
(C8), 128.29 (C6), 135.54 (C8a), 142.01 (C4a), 168.64
(C=O). Found, %: C 38.37; H 3.16; Br 19.58; I 31.16;
N 3.45. C13H13BrINO. Calculated, %: C 38.45; H 3.23;
Br 19.68; I 31.25; N 3.45.
lene chloride was cooled to –30°C, and trifluoroacetyl
nitrate prepared by mixing 0.32 g (4 mmol) of ammo-
nium nitrate and 2.5 g (12 mmol) of trifluoroacetic
anhydride in 2 mL of methylene chloride was added.
After 30 min, the mixture was poured onto ice (20 g),
and the product was extracted into 50 mL of methylene
chloride. The organic phase was washed with water
(10 mL) and dried over Na2SO4, the solvent was
removed under reduced pressure, and the residue was
crystallized from chloroform. Yield 0.18 g (31%), light
brown transparent crystals, mp 231–233°C (from
CHCl3). 1H NMR spectrum (DMSO-d6), δ, ppm: 2.35 s
2
(3H, CH3), 2.64 d (1H, 1-H, J = 17.4 Hz), 2.95–
3.05 m (1H, 1-H), 4.31 t (1H, 8b-H, J = 8.0 Hz), 5.74 d
3
(1H, 3a-H, J = 8.0 Hz), 6.02–6.07 m (2H, 2-H, 3-H),
8.45 d (1H, 6-H, J = 2.0 Hz), 8.50 d.d (1H, 8-H, J =
1.4, 2.0 Hz). Found, %: C 53.87; H 3.76; N 14.47.
C13H11N3O5. Calculated, %: C 53.98; H 3.83; N 14.53.
1-[(3aR*,8bR*)-7-Bromo-1,3a,4,8b-tetrahydro-
cyclopenta[b]indol-4-yl]ethanone (VIb). a. A solu-
tion of 4.65 g (11 mmol) of compound Vb in 20 mL of
piperidine was heated for 8 h under reflux (TLC).
Excess piperidine was distilled off under reduced
pressure, the residue was treated with a 5% solution of
sodium hydrogen carbonate and extracted with 250 mL
of chloroform, and the extract was dried over MgSO4
and evaporated under reduced pressure to isolate 3 g
(98%) of crude product VIb as an amorphous powder.
Crystallization from ethanol gave 2.26 g (74%) of VIb
as grayish crystals with mp 153–154°C (from EtOH).
1H NMR spectrum (CDCl3), δ, ppm: 2.34 s (3H, CH3),
2.41 s (3H, CH3, minor), 2.63 d.quint (1H, 1-H, J =
1-[(3aR*,8bR*)-7-Nitro-1,3a,4,8b-tetrahydro-
cyclopenta[b]indol-4-yl]ethanone (VIII) was isolated
by chromatography (silica gel, benzene–ethyl acetate,
9:1) of the residue obtained after removal of the
solvent from the mother liquor. Yield 0.146 g (30%),
yellowish crystals, mp 153–154°C (from MeOH),
1
Rf 0.41 (C6H6–EtOAc, 9:1). H NMR spectrum
(CDCl3), δ, ppm: 2.42 s (3H, CH3), 2.71 d (1H, 1-H,
J = 16.9 Hz), 3.08 d.d.q (1H, 1-H, J = 2.0, 8.0,
16.9 Hz), 4.15 t (1H, 8b-H, J = 8.0 Hz), 5.50 d (1H,
3
3a-H, J = 8.0 Hz), 5.82–8.87 m (1H, 3-H), 6.05–
2
2.0, J = 17.0 Hz), 2.99 d.d.q (1H, 1-H, J = 2.0, 8.3,
6.11 (1H, 2-H), 6.07 s (1H, 8-H), 6.13 d.d.d (1H, 6-H,
2J = 17.0 Hz), 4.07 t (1H, 8b-H, J = 8.3 Hz),
5.35 d.quint (1H, 3a-H, J = 1.5, 8.3 Hz), 5.77–5.80 m
(1H, 3-H), 5.97–6.02 m (1H, 2-H), 7.27 d (1H, 8-H,
J = 1.3 Hz), 7.31 d.d (1H, 6-H, J = 1.3, 8.5 Hz), 8.08 d
(1H, 5-H, J = 8.5 Hz). Found, %: C 56.01; H 4.27;
Br 27.99; N 4.96. C13H12BrNO. Calculated, %:
C 56.14; H 4.35; Br 28.13; N 5.04.
1
J = 0.8, 2.3, 8.6 Hz). H NMR spectrum (acetone-d6),
δ, ppm: 2.40 s (3H, CH3), 2.72 d (1H, 1-H, J = 0.5,
17.2 Hz), 3.10 d.d.d.q (1H, 1-H, J = 0.6, 2.0, 8.2,
17.2 Hz), 4.25 t (1H, 8b-H, J = 8.2 Hz), 5.69 d.quint
(1H, 3a-H, J = 1.8, 8.2 Hz), 5.97–6.08 m (1H, 2-H,
3-H), 8.11 d.d.d (1H, 5-H, J = 0.7, 2.4, 8.5 Hz), 8.13 s
(1H, 8-H), 8.26 d (1H, 6-H, J = 8.5 Hz). Found, %:
C 63.81; H 4.90; N 11.38. C13H12N2O3. Calculated, %:
C 63.93; H 4.95; N 11.47.
b. Compound VIa, 100 mg (0.5 mmol), was
dissolved in 2 mL of methylene chloride, 89 mg
(0.5 mmol) of N-bromosuccinimide was added, and the
mixture was stirred for 12 h at room temperature
(TLC). The solvent was distilled off under reduced
pressure, and the residue was subjected to column
chromatography on silica gel using benzene–ethyl
acetate (9:1) as eluent. Yield 95 mg (60%). Samples of
VIb obtained as described in a and b were identical in
physicochemical characteristics.
1-[(3aR*,8bR*)-7-Azido-1,3a,4,8b-tetrahydro-
cyclopenta[b]indol-4-yl]ethanone (IX). A mixture of
0.278 g (1 mmol) of compound VIb, 0.13 g (2 mmol)
of sodium azide, 0.02 g (0.1 mmol) of copper(I)
iodide, 0.035 g (0.3 mmol) of L-proline, and 0.012 g
(0.3 mmol) of sodium hydroxide in 1.5 mL of ethanol
and 0.5 mL of water was heated for 24 h under reflux.
When the reaction was complete (TLC), the mixture
was washed with 50 mL of water and extracted with
chloroform (3×75 mL), the combined extracts were
dried over MgSO4 and evaporated under reduced pres-
1-[(3aR*,8bR*)-5,7-Dinitro-1,3a,4,8b-tetrahydro-
cyclopenta[b]indol-4-yl]ethanone (VII). A solution of
0.398 g (2 mmol) of compound VIa in 1 mL of methy-
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SYNTHESIS OF 7-BROMO, 7-PHENYLETHYNYL, 7-AZIDO, AND 7-NITRO
53
sure, and the residue was subjected to chromatography
on silica gel. The first fraction contained 93 mg of
a mixture of compounds VIb and IX at a ratio of 2:1,
and from the second fraction we isolated 0.051 g
(21%) of compound IX, mp 112–114°C. Rf 0.48
From the next fractions we isolated 0.297 g of
a mixture of compound XI and initial bromo derivative
VIb at a ratio of 2:1.
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ppm: 2.34 s (3H, CH3), 2.41 s (3H, CH3, minor),
2
2.63 d (1H, 1-H, J = 17.0 Hz), 3.00 d.d.q (1H, 1-H,
2J = 17.0, J = 8.3, 2.0 Hz), 3.92 t (1H, 8b-H, minor, J =
8.0 Hz), 4.06 t (1H, 8b-H, J = 8.0 Hz), 5.39 d.quint
(1H, 3a-H, J = 8.0, 2.0 Hz), 5.70–6.00 m (2H, 2-H,
3-H), 6.83 s (1H, 8-H), 6.86 d.d.d (1H, Harom, J = 0.8,
2.2, 8.5 Hz), 8.17 d (1H, 5-H, J = 8.5 Hz). 13C NMR
spectrum (CDCl3), δC, ppm: 23.67 (CH3), 39.58 (C1),
42.49 (C8b), 71.57 (C3a); 114.86, 118.49, 118.58,
128.16, 134.57 (C2, C3, C5, C6, C8); 135.38, 137.54,
138.68 (C4a, C7, C8a); 167.95 (C=O). Mass spectrum,
m/z: 240.1 [M]+, 212.1 [M – N2]+, 169.1 [M –
COCH3 – N2]+. Found, %: C 64.88; H 4.98; N 23.24.
C13H12N4O. Calculated, %: C 64.99; H 5.03; N 23.32.
M 240.1006.
1-[(3aR*,8bR*)-7-(Phenylethynyl)-1,3a,4,8b-
tetrahydrocyclopenta[b]indol-4-yl]ethanone (XI).
A mixture of 0.278 g (1 mmol) of compound VIb,
0.107 g (1.05 mmol) of phenylacetylene, 0.042 g of
10% Pd/C, 0.042 g (0.16 mmol) of triphenylphosphine,
and 0.01 g of copper(I) iodide in 2.5 mL of triethyl-
amine and 1.5 mL of acetonitrile was heated for 16 h
under reflux. When the reaction was complete (TLC),
the mixture was evaporated under reduced pressure,
and the residue was subjected to column chromatog-
raphy on silica gel using benzene as eluent. Yield
0.036 g (12%), deliquescent material on exposure to
9. Kong, D.-L., He, L.-H., and Wang, J.-Q., Catal.
Commun., 2010, vol. 11, p. 992.
10. Bernard, A., Kumar, A., Jamir, L., Sinha, D., and
Sinha, U.B., Acta Chim. Slov., 2009, vol. 56, p. 457.
11. Zhu, W. and Ma, D., Chem. Commun., 2004, p. 888.
12. Jiang, L., Lu, X., Zhang, H., Jiang, Y., and Ma, D.,
1
J. Org. Chem., 2009, vol. 74, p. 4542.
air, Rf 0.5 (C6H6–EtOAc, 9:1). H NMR spectrum
13. Tolstikov, G.A., Mustafin, A.G., Gataullin, R.R., and
Abdrakhmanov, I.B., Izv. Akad. Nauk, Ser. Khim., 1992,
p. 1449.
14. Skladchikov, D.A., Suponitskii, K.Yu., Abdrakhma-
nov, I.B., and Gataullin, R.R., Russ. J. Org. Chem.,
2012, vol. 48, p. 957.
15. Skladchikov, D.A., Buranbaeva, R.S., Fatykhov, A.A.,
Ivanov, S.P., and Gataullin, R.R., Russ. J. Org. Chem.,
2012, vol. 48, p. 1550.
16. Comprehensive Organic Chemistry, Barton, D. and
Ollis, W.D., Eds., Oxford: Pergamon, 1979, vol. 2.
Translated under the title Obshchaya organicheskaya
khimiya, Moscow: Khimiya, 1983, vol. 4, p. 426.
(CDCl3), δ, ppm: 2.36 s (3H, CH3), 2.45 s (3H, CH3,
2
minor), 2.68 d.quint (1H, 1-H, J = 17.0, J = 2.0 Hz),
2
3.00 d.d.q (1H, 1-H, J = 17.0, J = 8.3, 2.0 Hz), 3.92 t
(1H, 8b-H, minor, J = 8.3 Hz), 4.08 t (1H, 8b-H, J =
8.3 Hz), 5.38 d.quint (1H, 3a-H, J = 8.3, 2.0 Hz), 5.78–
5.82 m (1H, 3-H), 5.97–6.02 m (1H, 2-H), 7.28–
7.41 m (7H, Harom), 8.17 d (1H, 5-H, J = 8.5 Hz).
13C NMR spectrum (CDCl3), δC, ppm: 23.94 (CH3),
39.79 (C1), 42.36 (C8b), 71.63 (C3a), 88.71 and 89.76
(C≡C); 117.41, 127.36, 127.54, 128.20, 131.82, 134.82
(C2, C3, C5, C6, C8, C4′); 128.41, 131.49 (C2′, C3′, C5′,
C6′); 118.49, 123.44, 136.14, 138.12 (C4a, C7, C8b, C1′);
127.03 (C8), 168.41 (C=O). Mass spectrum, m/z: 299.1
[M]+, 256.1 [M – COCH3]+. Found, %: C 84.13;
H 5.63; N 4.62. C21H17NO. Calculated, %: C 84.25;
H 5.72; N 4.68. M 299.1305.
17. Eliel, E.L., Wilen, S.H., and Doyle, M.P., Basic Organic
Stereochemistry, New York: Wiley, 2001. Translated
under the title Osnovy organicheskoi stereokhimii,
Moscow: Binom, 2007, p. 355.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 50 No. 1 2014