Substituted dibenzo[2,3:5,6]-pyrrolizino[1,7-bc]indolo[1,2,3-lm]carbazoles: A series of new electron donors

Article abstract of DOI:10.1016/j.tet.2013.02.007

The synthesis and spectroscopic properties of a series of new organic electron donors derived from dibenzo[2,3:5,6]pyrrolizino-[1,7-bc]indolo[1,2,3- lm]carbazole are described. These compounds can be considered as planar hybrids of carbazole and p-phenylenediamine and possess high thermal stability. The electron donating properties and one- and two-photon spectroscopic features of methoxy derivatives are very sensitive to the number and positions of the methoxy groups. The X-ray structure of the 2,11-dimethoxy derivatives features slipped π-stacks and short interplanar distance between the molecules in the stacks similar to those found in the unsubstituted derivative.

Full text of DOI:10.1016/j.tet.2013.02.007

Accepted Manuscript
Substituted dibenzo[2,3:5,6]-pyrrolizino[1,7-bc]indolo[1,2,3-lm]carbazoles: a series of
new electron donors
Morgane Rivoal, Laura Bekere, David Gachet, Vladimir Lokshin, Wladimir Marine,
Vladimir Khodorkovsky
PII:
S0040-4020(13)00180-4
10.1016/j.tet.2013.02.007
TET 23996
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 3 November 2012
Revised Date: 14 January 2013
Accepted Date: 1 February 2013
Please cite this article as: Rivoal M, Bekere L, Gachet D, Lokshin V, Marine W, Khodorkovsky V,
Substituted dibenzo[2,3:5,6]-pyrrolizino[1,7-bc]indolo[1,2,3-lm]carbazoles: a series of new electron
donors, Tetrahedron (2013), doi: 10.1016/j.tet.2013.02.007.
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Substituted dibenzo[2,3:5,6]-pyrrolizino[1,7-
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Morgane Rivoal, Laura Bekere, David Gachet, Vladimir Lokshin, Wladimir Marine, Vladimir Khodorkovsky
CNRS, Centre Interdisciplinaire de Nanoscience de Marseille (CINaM) UMR CNRS 7325), 13288, Marseille,
Aix-Marseille Universite, 13288 Marseille Cedex 9, France

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1
Tetrahedron
journal homepage: www.elsevier.com
Substituted dibenzo[2,3:5,6]-pyrrolizino[1,7-bc]indolo[1,2,3-lm]carbazoles: a series
of new electron donors
Morgane Rivoal, Laura Bekere, David Gachet, Vladimir Lokshin, Wladimir Marine and Vladimir
Khodorkovsky*
CNRS, Centre Interdisciplinaire de Nanoscience de Marseille (CINaM) UMR CNRS 7325), 13288, Marseille, Aix-Marseille Universite, 13288 Marseille Cedex
9, France
ARTICLE INFO
ABSTRACT
Article history:
Received
The synthesis and spectroscopic properties of a series of new organic electron donors derived
from dibenzo[2,3:5,6]pyrrolizino-[1,7-bc]indolo[1,2,3-lm]carbazole are described. These
Received in revised form
Accepted
Available online
compounds can be considered as planar hybrids of carbazole and p-phenylenediamine and
possess high thermal stability. The electron donating properties and one- and two-photon
spectroscopic features of methoxy derivatives are very sensitive to the number and positions of
the methoxy groups. The X-ray structure of the 2,11-dimethoxy derivatives features slipped π-
stacks and short interplanar distance between the molecules in the stacks similar to those found
in the unsubstituted derivative.
Keywords:
Electron Donors
Fluorescence
Carbazole
2009 Elsevier Ltd. All rights reserved.
Indole
1. Introduction
structural variations of carbazoles have demonstrated the
potential of indolocarbazoles5,8,20 and bisindoloquinolines21 for
Currently, small organic π-conjugated molecules constitute
one of the most extensively studied field of research owing to
their potential as components of charge transporting, nonlinear
optical and other advanced materials,1 in particular, organic field-
effect transistors.2,3 Derivatives of triaryl amines and carbazole,
especially indolo[3,2-b]carbazoles, are considered to be the most
promising classes of organic electron donors and are the subjects
of intensive investigations. Research efforts in this field cover a
broad spectrum of topics for biological targets4 and numerous
investigations of potential applications of such materials as
components for organic light-emitting diodes,5,6 organic thin-film
transistors7 and photovoltaic cells.8 The charge transfer within
aromatic amines occurs in a chain of redox processes between the
neutral molecule and its cation radical in their ground state,9
which requires high stability of both electron donors and their
oxidized forms. Thus, the known instability of the triaryl amine
cation radicals, which undergo dimerization to form
tetraarylbenzidines10 was the driving force to design fully
reversible redox systems involving the p-phenylenediamine
moiety.11-13
applications involving charge transfer. Recently, we showed that
a new heterocyclic system, dibenzo[2,3:5,6]pyrrolizino-[1,7-
bc]indolo[1,2,3-lm] carbazole, which can be considered as a
planar hybrid of carbazole and p-phenylenediamine, can readily
be prepared from commercial precursors and possesses high
thermal stability and strong electron donor properties comparable
to tetra- and pentacene.22 However, the only known derivative of
the parent compound with four methoxy groups at 2,3,11,12
positions was highly insoluble22 that prevented the spectroscopic
and electrochemical characterization of this compound, which
was supposed to be a stronger electron donor. Here we report on
the preparation and properties of a number of other substituted
derivatives which solubility is sufficient for, at least,
spectroscopic characterization.
2. Results and discussion
2.1. Synthesis
Of two possible synthetic routes employed previously for the
synthesis of the parent unsubstituted derivative 1 (R = R1 = H),22
the cyclization of the dichloro substituted derivatives 2 in the
presence of CuI and a base is certainly the most suitable for the
preparative purpose.
Carbazoles, as a larger planar aromatic system, possess also
strong fluorescence in both solution and solid state14,15 and
enhanced thermal stability. These derivatives can also serve as
the efficient electron donating moieties in second harmonic
generating16 and two-photon absorbing (TPA) chromophores.17,18
However, their oxidation gives rise to oligomerization.19 Further
Thus, the substituted 6,12-diaryl-5,11-dihydroindolo[3,2-
b]carbazoles 2 can serve as convenient precursors of derivatives

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2
Tetrahedron
of 1. The known synthetic routes toward derivatives 2 are based
on the condensation of aryl aldehydes and indoles. One of the
approaches involves iodine catalyzed self-condensation of 3,3’-
bis(indolyl)methanes,23 whereas the direct condensation of an
indole and an aromatic aldehyde in the presence of iodine was
supposed to afford isomeric 6,12-diaryl-5,7-dihydroindolo[2,3-
b]carbazoles.24 It was demonstrated later25 that the purported
isomeric 6,12-diphenyl [2,3-b] derivative is actually 6,12-
diphenyl-5,6,11,12-tetrahydroindolo[3,2-b]carbazole. Moreover,
the reported high yields of the products were not reproducible.
An alternative catalyst, hydroiodic acid, was proposed25 as an
efficient catalyst of the reaction of indoles with aromatic
aldehydes.
HO
HOOC
Cl
N
Cl
H
H
N
N
N
H
H
H
Cl
Cl
O
COOH
5e
4
Derivatives 3g and 3h afforded the same deeply colored
insoluble product. This compound may correspond to the
oxidized quinoid form of 2h (4) and was not further investigated.
Derivatives 2c and 2d were prepared from 5-methoxyindole, the
corresponding methoxy 2-chlorobenzaldehyde and catalytic
amount of hydroiodic acid according to the published
procedure.25
R1
R2
R2
R
R
R1
Cl
HN
N
N
NH
Cl
R1
R
R
R2
R2
R1
1
2
Another approach involves a thermal reaction of 3-alkylated
indole derivatives, which form in a three-component solvent-free
reaction of indole, aromatic aldehydes and N,N-
dimethylbarbituric acid.26
Fig. 1: Molecular and crystal structure of 5e (thermal ellipsoids
are presented at 50% of probability).
R2
R1
O
N
O
The formation of dihydroindolocarbazoles 2 was always
accompanied by the formation of some amount of the tetrahydro
derivatives 5. These derivatives seem indeed to be the primary
reaction products, which undergo relatively rapid oxidation in
solution, but owing to the low solubility they precipitate out of
the reaction mixture avoiding thus further oxidation. In
particular, we isolated the tetrahydro derivative 5e, which is less
soluble than 2e. Interestingly, this compound forms the same
6,12-trans isomer (Fig. 1) isolated in the case of the 6,12-
diphenyl analog.25 The tetrahydro derivatives 5 can be oxidized
to 2 by refluxing their solutions in the presence of iodine.25
However, we found that in the presence of a base (TBAOH)
during the cyclization step, the oxidation of derivatives 5 occurs
easily by residual oxygen and may additionally be catalized by
CuI so that the separation of 2 and 5 from their mixtures is not
necessary.
2
Cl
N
R
O
N
H
3 a) R = R1 = R2 = H; b) R = OMe, R1 = R2 = H
c) R = R1 = OMe, R2 = H; d) R = R2 = OMe, R1 = H;
e) R = COOH, R1 = R2 = H; f) R = NO2, R1 = R2 = H;
g) R = OCH2Ph, R1 = R2 = H; h) R = OH, R1 = R2 = H
We tested both the above approaches using 2-
chlorobenzaldehydes and found that the route involving 3-
alkylated indole derivatives 326 is the most general and
convenient in the cases when 2-chlorobenzaldehyde itself is used.
Derivatives 3a, b, e-h were prepared in fair to excellent yields
according to the procedure27 as colorless crystals and their
structures were confirmed by the X-ray analysis. However, we
were unable to prepare derivatives 3c and 3d from the
corresponding methoxy 2-chlorobenzaldehydes. The conversion
of 3 into indolocarbazoles 2 required much more time than
reported.26 Thus, 2a was obtained in 40 % yield after 20 h of
reflux in acetic acid (instead of 45% during 40 min of reflux
reported in26). In some cases, using formic acid considerably
increased the yields and shortened the reaction time, however, the
purification of the compounds from the side products becomes
more complicated.
The mixtures of derivatives 2a-e/5a-e underwent cyclization
under the conditions described earlier for 1a and the synthesis
can be scaled up without the loss in the yields. The mixture of
2f/5f did not cyclize even under drastic conditions. New
derivatives 1b and c form yellow needle-like crystals limitedly
soluble in non-polar solvents (about 10-4 M in toluene) similarly
to 1a, and 1d forms dark yellow microcrystals with metallic
luster, soluble in benzonitrile (about 10-5 M). These compounds
possess high thermal stability: they do not melt and sublime
above 300°C. Derivative 1e is insoluble in most common organic
solvents, but forms soluble salts upon addition of TBAOH or
KOH. Yellow prisms of 1b suitable for the X-ray analysis were
grown from benzonitrile.

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3
increase with the increasing number of the methoxy groups:
from 4 nm (1a) up to 19 nm (1d). The p-methoxy substituents
diminish the intensity of the longest wavelength absorption band:
the molar absorption coefficient of 1b is 9 000 M-1cm-1, more
than twice smaller compared to 20 200 M-1cm-1 measured for 1a.
The fluorescence quantum yields in toluene for 1b and 1c were
found to amount 41 and 53%, respectively.
a)
b)
Fig.2. Molecular (a) and crystal (b) structures of 1b. Selected
bond lengths in Å: C1–C6 1.431(3); C6-C7 1.460(3); C7-C8
1.399(3); C8 C9 1.393(3); C9 C10 1.462(3); C10 C15 1.431(3);
C15 N1 1.400(3); C1 N1 1.406(3); C8 N1 1.372(3)
The X-ray structure determination showed that the molecules
of 1b are almost planar, the terminal benzenic rings are twisted
from the molecular plane less than observed for 1a (1.5° vs. 5°,
respectively). The methoxy groups are twisted by 11.3° from the
molecular plane. The molecules in crystal form slipped π-stacks
with the distance between each mean square molecular planes of
3.29 Å (that is even shorter than found for 1a: 3.380 Å) (Fig. 2).
Fig. 3. Normalized absorption (a) and fluorescence (b) spectra:
1a – 1c in toluene, 1d in benzonitrile.
2.2. UV-Vis absorption and fluorescence spectra
The basic features of UV-Vis absorption and fluorescence
spectra of 1a have already been discussed in ref.22. The positions
of the longest wavelength absorption maxima of 1b - d undergo
strong shifts upon increasing the number of the methoxy groups
(Fig. 3).
The two-photon fluorescence excitation spectra of 1b and 1c
(Fig. 4) resemble that of 1a and exhibit broad vibronically split
bands stretching from 900 nm down to 700 nm and, probably,
below. Indeed, solutions of 1b and 1c fluoresce upon irradiation
by 532 and 640 nm lasers. The two-photon absorption cross
sections were found to amount 30 and 60 GM for 1b and 1c,
respectively, at 740 nm, larger than found for 1a (20 GM at 730
nm).
The direction of the shifts strongly depends on the substitution
position and two methoxy groups at 2,11 positions (1b) give rise
to ca. 20 nm red shift. Further substitution by the two methoxy
groups at 8,17 positions (1d) moves the longest wavelength
absorption band toward red by 20 nm, while the substitution by
the two methoxy groups at 7, 16 position (1c) brings about a blue
shift ca. 15 nm compared to 1b. Only weak positive
solvatochromism of about 4 – 6 nm roughly correlating with the
refractive indices of solvents was observed. The Stokes shifts
The absorption and fluorescence spectra of the dipotassium
and TBA salts of 1e are similar to those of 1a.
2.3. Electron donating properties

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4
Tetrahedron
The low solubility of derivatives 1 prevented the detailed
symmetrically substituted derivative 1d is calculated to be the
strongest donor of the series with the IP by 0.67 eV lower than
that of 1a. The AM1 calculation results showed a similar trend
judging by the HOMO/LUMO energy changes. The discussed
above shifts in the position of the longest wavelength absorption
maxima within the series 1a – 1d are well reproduced by the
calculations. The calculated oscillator strengths f are also in
agreement with the experimental molar absorption coefficients
found for 1a and 1b.
electrochemical studies. The propensity of the oxidized form of
1a to deposit on the electrode as a black shining film during the
CV experiments22 is even stronger for the substituted derivatives.
We were able to observe the oxidation peak only for 1b in warm
DMSO at about 0.5 V (Pt electrode, TBAPF6, vs. SCE). It is a
considerable shift compared to the unsubstituted derivative
(about 1 V vs. SCE under the same conditions). Addition of
strong
acceptors
(tetracyanoethylene
or
tetracyano-
quinodimethane) to solutions of 1b in toluene led to immediate
development of dark green color and eventual formation of a
black precipitate.
3. Conclusion
The new derivatives of dibenzo[2,3:5,6]pyrrolizino-[1,7-
bc]indolo[1,2,3-lm]carbazole possess many of the properties
required by applications involving charge transporting and
optical phenomena. The remarkable sensitivity of the parent
heterocycle to the number and position of substituents suggests
the possibility of further tuning the electron donating ability and
the electronic transition energies.
Table 1. Quantum mechanical calculations summary
EHOMO/LUMO
Compd
IP (eV) EA (eV)
EET1(f)
(AM1)(eV)
-8.05/-1.25
-7.91/-1.33
-7.79/-1.18
-7.67/-1.24
1a
1b
1c
1d
6.53
6.26
5.95
5.86
0.64
0.66
0.42
0.55
2.98 (0.14)
2.78 (0.08)
2.85 (0.16)
2.57 (0.08)
The energy of the 1st electronic transition calculated by the TD DFT
1
method.
a)
4. Experimental section
4.1. General
All chemicals including the solvents were used without prior
drying except DMF, which was freshly distilled over P2O5. All
1
reagents and solvents were of reagent grade. The H-NMR and
13C-NMR spectra were recorded on a Bruker AC-250 (1H
spectra: 250 MHz; 13C spectra: 62.5 MHz) using TMS as an
internal standard. Chemical shifts (δ) are given in ppm and
coupling constants (J) in Hz. Elemental analyses were performed
on a Thermo Finnigan Flash EA1112 series. Melting points
(uncorrected) were determined using a Buchi-510 apparatus. X-
Ray crystallography data were collected on a Bruker-Nonius
KappaCCD diffractometer with CCD detector using MoKα
radiation (λ=0.71073 Å). UV-Vis absorption spectra were
recorded on an Ocean Optics USB 4000 spectrophotometer
combined with UV-Vis-IR Light Source Micropack DH-2000.
Fluorescence spectra were recorded on a Fluorolog-3 (Jobin
Yvon) fluorimeter. The quantum yields of fluorescence were
determined in toluene at 20 °C using quinine sulfate in a solution
of H2SO4 (0.1 M) as a reference.
b)
Fig. 4. Two-photon (solid curves) and one-photon (dashed
curves) fluorescence excitation spectra of 1b (a) and 1c (b) in
toluene. For the two-photon spectra the X-axis values are λ/2.
Commercially available reagents were used as received.
Two-photon absorption cross sections were determined by
In order to reveal the effect of the substitution on the electron
donating properties of the new heterocyclic system, we
performed quantum mechanical calculations at the semiempirical
(AM1//AM1) and DFT (TD B3LYP/6-31G(d,p)//B3LYP/6-
31G(d,p)) levels.28 The ionization potentials (IP) and electron
affinities (EA) were calculated as the energy difference between
the neutral molecule and the corresponding radical cation (IP)
and between the radical anion and neutral molecule (EA). The
major results are collated in Table 1. The effect of the methoxy
groups at 8,17 positions on the electron donating properties
should be considerably stronger than at 7,16 positions. Thus, the
photoluminescence excitation spectroscopy.
A
tunable
Ti:Sapphire femtosecond laser (MaiTai HP, Spectra-Physics, 150
fs pulses at 80 MHz) in the 690-1050 nm range was used for
excitation of toluene solutions in a 1 cm quartz cell. The laser
beam was focused in the cell using a NA 0.4 objective. The
generated photoluminescence was collected in a 90° geometry
and filtered with a short-pass interference filter. It was then sent
into a monochromator (Spectra Pro 500i, Acton) before being
detected
by
a
ICCD
camera
(Roper
Scientific).
Photoluminescence spectra were recorded for excitation
wavelength ranging typically from 700 to 950 nm, with a 5 nm

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5
span. Integration time ranged from 10 ms to 2 s. The average
15.2568(4),
= 112.403(1), space group P21/n. Deposition
laser power was typically kept around 500 mW. Two-photon
absorption spectra were then calculated by integration of the
photoluminescence spectrum for each excitation wavelength.
They were normalized by the integration time and the square of
the average laser power.
number CCDC 905656.
4.2.1.4. 5-[(2-chlorophenyl)(5-nitro-1H-indol-3-yl)methyl]1,3-
dimethylpyrimidine-2,4,6(1H,3H,5H)-trione 3f. From 5-
nitroindole, at 90°C, 46% yield, yellow crystals from acetone,
1
m.p. 141-143°C. H NMR (DMSO-d6): δ = 2.93 (s, 3H, CH3),
3
3
The two-photon cross sections were determined by comparing
the two-photon absorption spectra with rhodamine B in methanol
and normalizing by their quantum yields. The known literature
values have been determined with the same typical pulse duration
of ~150 fs.29
3.03 (s, 3H, CH3), 4.53 (d, J = 3.95 Hz, 1H, CH), 5.60 (d, J =
3.79 Hz, 1H, CH), 7.60 (m, 8H, CH), 11.81 (s, 1H, NH). 13C
NMR (DMSO-d6): δ = 167.64 (C), 167.53 (C), 151.18 (C),
140.44 (C), 139.12 (C), 137.04 (C), 132.42 (C), 131.27 (CH),
129.27 (CH), 129.00 (CH), 128.39 (CH), 126.92 (CH), 125.65
(C), 116.88 (CH), 114.98 (C), 114.67 (CH), 112.28 (CH), 52.92
(CH), 40.57 (CH), 28.17 (CH3), 28.02 (CH3). C21H17Cl1N4O5.
Unit cell parameters: a = 9.3874(2), b = 25.5888(6), c =
4.2. Synthesis
4.2.1. A general procedure for 5-[(2-chlorophenyl)(1H-indol-3-
yl)methyl]-1,3 dimethylpyrimidine-2,4,6(1H,3H,5H)-triones (3).
Equimolar amounts of an indole derivative, 2-chloro
benzaldehyde and N,N-dimethylbarbituric acid were heated for
15 min. The reaction mixture was cooled down and a mixture of
petroleum ether:ethanol (4:1) was added. The precipitate was
filtered off and washed with ethanol. Crystals of 3 were obtained
by crystallization from ethanol. The identities of derivatives 3
were confirmed by the X-ray structure determination and the
crystal structures have been deposited at the Cambridge
Crystallographic Data Centre.
8.8179(2),
= 101.582(1), space group P21/c. Deposition
number CCDC 905659.
4.2.1.5.
5-[[5-(benzyloxy)-1H-indol-3-yl](2-chlorophenyl)
methyl]-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione
3g.
From 5-benzyloxyindole, at 90°C, 66% yield, m.p. 150-152°C.
1H NMR (DMSO-d6): δ = 2.89 (s, 3H, CH3), 3.05 (s, 3H, CH3),
4.39 (d, 3J = 3.63, 1H, CH), 4.95 (s, 2H, CH2), 5.43 (d, 3J = 3.32,
1H, CH), 6.60 (s, 14H, CH), 10.91 (s, 1H, NH). 13C NMR
(DMSO-d6): δ = 167.87 (C), 167.65 (C), 152.03 (C), 151.21 (C),
137.43 (C), 132.39 (C), 131.30 (C), 131.18 (C), 129.02 (C),
128.62 (CH), 128.26 (CH), 127.52 (CH), 126.62 (CH), 124.71
(CH), 112.25 (CH), 111.98 (C), 111.79 (CH), 101.57 (CH), 69.77
(CH2), 53.19 (CH), 41.35 (CH), 28.11 (CH), 27.90 (CH).
C28H24Cl1N3O4 x H2O. Unit cell parameters: a = 7.8046(2), b =
4.2.1.1.
5-[(2-chlorophenyl)(1H-indol-3-yl)methyl]-1,3
dimethylpyrimidine-2,4,6(1H,3H,5H)-trione 3a. From indole, at
1
85°C, 80% yield, m.p. 197-199°C. H NMR (DMSO-d6): δ =
2.88 (s, 3H, CH3), 3.04 (s, 3H, CH3), 4.40 (d, 3J = 3.63, 1H, CH),
3
8.2404(2), c = 20.6471(6),
= 87.541(1),
= 86.842(1),
=
5.53 (d, J = 3.48, 1H, CH), 7.06 (m, 9H, CH), 11.04 (s, 1H,
NH).13C NMR (DMSO-d6): δ = 167.84 (C), 167.63 (C),
151.18(C), 137.59 (C), 135.86 (C), 132.35 (C), 131.39 (CH),
129.00 (CH), 128.62 (CH), 126.61 (CH), 126.26 (C), 123.94
(CH), 121.35 (CH), 118.73 (CH), 117.63 (CH), 112.19 (C),
111.57 (CH), 53.13 (CH), 41.28 (CH), 28.09 (CH3), 27.87 (CH3).
C21H18Cl1N3O3. Unit cell parameters: a = 8.3515(2), b =
85.098(1), space group P -1. Deposition number CCDC 905658.
4.2.1.6.
5-[(2-chlorophenyl)(5-hydroxy-1H-indol-3-
yl)methyl]1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione 3h.
1
From 5-hydroxyindole, at 90°C, 46%, m.p. 154-156°C. H NMR
(DMSO-d6): δ = 2.89 (s, 3H, CH3), 3.06 (s, 3H, CH3), 4.36 (d, 3J
3
4
= 3.48, 1H, CH), 5.42 (d, J = 3.48, 1H, CH), 6.44 (d, J = 2.05,
29.0327(8), c = 7.7279(2),
= 94.731(2), space group P 21/c.
3
4
1H, CH), 6.57 (dd, J = 8.61, J = 2.29, 1H, CH), 7.31 (m, 6H,
CH), 10.74 (s, 1H, NH). 13C NMR (DMSO-d6): δ = 167.91 (C),
167.69 (C), 151.23 (C), 150.48 (C), 137.73 (C), 132.37 (C),
131.48 (CH), 130.34 (CH), 128.99 (CH), 128.58 (CH), 127.06
(C), 126.61 (CH), 124.15 (CH), 111.93 (CH), 111.80 (CH),
101.74 (CH), 53.08 (CH), 41.41 (CH), 28.12 (CH3), 27.92 (CH3).
C21H18Cl1N3O4 x C2H5OH. Unit cell parameters: a = 7.7795(2), b
Deposition number CCDC 905654.
4.2.1.2. 5-[(2-chlorophenyl)(5-methoxy-1H-indol-3-yl)methyl]-
1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione 3b. From 5-
methoxyindole, at 85°, 75% yield, m.p. 147-149°C. 1H NMR
(CDCl3): δ = 3.00 (s, 3H, CH3), 3.21 (s, 3H, CH3), 3.72 (s, 3H,
3
3
CH3), 4.40 (d, J = 3.16, 1H, CH), 5.68 (d, J = 3.16, 1H, CH),
7.10 (m, 8H, CH), 8.04 (s, 1H, NH). 13C NMR (CDCl3): δ =
168.07 (C), 167.68 (C), 164.65 (C), 154.18 (C), 136.69 (C),
133.41 (C), 131.02 (C), 130.90 (CH), 129.51 (CH), 128.88 (CH),
127.05 (C), 126.70 (CH), 123.84 (CH), 114.34 (C), 112.69 (CH),
111.84 (CH), 100.65 (CH), 55.69 (OCH3), 53.87 (CH), 42.80,
28.74 (CH3), 28.45 (CH3). C22H20Cl1N3O4. Unit cell parameters:
= 8.2998(3), c = 17.6713(6), = 102.884(1), = 91.024(1),
=
95.201(3), space group P -1. Deposition number CCDC 905657.
4.2.2.
Mixtures
of
6,12-bis(2-chlorophenyl)-5,11-
(2) and 6,12-bis(2-
dihydroindolo[3,2-b]carbazoles
chlorophenyl)-5,6,11,12-tetrahydroindolo[3,2-b]carbazoles (5).
a) A solution of 3 (16.1 mmol) in 40 ml of glacial acetic acid was
refluxed during 20h. The reaction mixture was cooled down, a
yellowish mixture of 2 and 5 was filtered off and washed
thoroughly with hot ethanol. The yields of 2a, b, e and f
containing 15 to 20% of the respective 5 (evidenced by the
a = 9.4793(2), b = 9.6922(2), c = 11.7006(3), = 74.031(1),
=
86.420(1), = 77.097(2), space group P -1. Deposition number
CCDC 906218.
4.2.1.3.
3-[(2-chlorophenyl)(1,3-dimethyl-2,4,6-
1
presence of the H NMR signal about 5.7 ppm) varied between
trioxohexahydropyrimidin-5-yl)methyl]-1H-indole-5-carboxylic
acid 3e. From indole-5-carboxylic acid at 95°C, 80% yield, m.p.
226-228°C. 1H NMR (DMSO-d6): δ = 2.91 (s, 3H, CH3), 3.03 (s,
5% (2e/5e), 40% (2a/5a), 74% (2f/5f) and 80% (2b/5b). The
mixtures were used in the next step without further purification.
b) A solution of 5-methoxyindole (3 mmol), 2-chloro-4(5)-
methoxybenzaldehyde (3 mmol) and hydroiodic acid (1.4
mmol)(57% water solution) in 20 ml of acetonitrile was refluxed
under Ar for 15 h. After evaporation of the solvent, the residue
was washed by methanol, filtered and washed with acetonitrile.
The resulting mixtures of 2c/5c (10% yield) and 2d/5d (4%
yield) were used in the next step without further purification.
Derivative 5e was isolated by crystallization of the mixture of 2e
and 5e from DMSO as colorless crystals involving one molecule
3
3
3H, CH3), 4.45 (d, J = 3.63, 1H, CH), 5.58 (d, J = 3.63, 1H,
CH), 7.48 (m, 8H, CH), 11.41 (s, 1H, NH). 13C NMR (75 MHz,
DMSO-d6): δ = 168.07 (C), 167.77 (C), 167.69 (C), 151.18 (C),
138.39 (C), 137.49 (C), 132.36 (C), 131.36 (CH), 129.16 (C),
128.81 (CH), 126.80 (CH), 125.93 (CH), 125.85 (CH), 122.74
(CH), 121.42 (CH), 120.38 (CH), 113.56 (C), 111.43 (CH), 53.08
(CH), 40.96 (CH), 28.13 (CH3), 27.97 (CH3). C22H18Cl1N3O5.
Unit cell parameters: a = 15.2196(3), b = 9.2427(2), c =

ACCEPTED MANUSCRIPT
6
Tetrahedron
8. Blouin, N.; Michaud, A.; Wakim, S.; Boudreault, P.-L. T.; Leclerc, M.;
Vercelli, B.; Zecchin, S.; Zotti, G. Macromol. Chem. Phys., 2006, 207,
166-174.
of DMSO. C32H26Cl2N2O5S1. Unit cell parameters:
a =
13.4133(4), b = 8.6773(2), c = 15.3735(4), = 101.709(1), space
group P 21/c. Deposition number CCDC 905653.
9. Stolka, M.; Yanus, J. F.; Pai, D. M. J. Phys. Chem., 1984, 88, 4707-
4714.
4.2.3.
Dibenzo[2,3:5,6]pyrrolizino[1,7-bc]indolo[1,2,3-
lm]carbazoles (1). The mixture of 2 and 5 (2.3 mmol), CuI (2.3
mmol) and tetrabutylammonium hydroxide (5.13 mmol) (40%
methanol solution) were suspended in 30 ml of freshly distilled
DMF under Ar and heated at 120°C during 24h. The mixture was
cooled down to room temperature, and the yellow precipitate was
filtered off and washed with MeCN. Pure products can be
obtained by crystallization from benzonitrile.
10. Seo, E. T.; Nelson, R. F.; Fritsch, J. M.; Marcoux, L. S.; Leedy, D. W.;
Adams, R. N. J. Am. Chem. Soc. 1966, 88, 3498-3503.
11. Thelakkat, M.; Schmidt, H. W. Adv. Mater. 1998, 10, 219-223.
12. Katsuma, K.; Shirota, Y. Adv. Mater. 1998, 10, 223-226.
13. Louie, J.; Hartwig, J. F. J. Am. Chem. Soc. 1997, 119, 11695-11696.
14. Palayangoda, S. S.; Cao, X.; Adhikari, R. M.; Neckers, D. C. Org. Lett.
2008, 10, 282-284.
15. Adhikari, R. M.; Mondal, R.; Shah, B. K.; Neckers, D. C. J. Org.
Chem., 2007, 72, 4727-4732.
4.2.3.1.
Dibenzo[2,3:5,6]pyrrolizino[1,7-bc]indolo[1,2,3-
lm]carbazole (1a). Yellow needles from benzonitrile identical to
16. Meshulam, G.; Berkovic, G.; Kotler, Z.; Ben-Asuli, A.; Mazor, R.;
Shapiro, L.; Khodorkovsky, V. Synth. Met. 2000, 115, 219-223.
17. Kotler, Z.; Segal, J.; Sigalov, M.; Ben-Asuli, A.; Khodorkovsky, V.
Synth. Met. 2000, 115, 269-273.
18. Vaganova, E.; Yitzchaik, S.; Sigalov, M.; Borst, J. W.; Visser, A.;
Ovadia, H.; Khodorkovsky, V. New. J. Chem. 2005, 29, 1044-1048.
19. Cattarin, S.; Mengoli, G.; Musiani, M. M.; Schreck, B. J. Electroanal.
Chem. 1988, 246, 87-98.
described in22 yield 73%.
4.2.3.2.
2,11-dimethoxydibenzo[2,3:5,6]pyrrolizino[1,7–
bc]indolo [1,2,3-lm]carbazole (1b). Yellow needles from
benzonitrile, 39% yield. Sublime above 300°C. C32H20N2O2. Unit
cell parameters: a = 5.7821(2), b = 16.3748(5), c = 23.1997(8),
space group P bca. Deposition number CCDC 905655.
20. Boudreault, P.-L. T.; Wakim, S.; Blouin, N.; Simard, M.; Tessier, C.;
Tao, Y.; Leclerc, M. J. Am. Chem. Soc. 2007, 129, 9125-9136.
21. Ahmed, E.; Briseno, A. L.; Xia, Y.; Jenekhe, S. A. J. Am. Chem. Soc.
2008, 130, 1118-1119.
22. Niebel, C.; Lokshin, V.; Ben-Asuli, A.; Marine, W.; Karapetian, A.;
Khodorkovsky, V. New J. Chem. 2010, 34, 1243-1246.
23. Deb, M. L.; Bhuyan, P. J. Synlett, 2008, 325-328.
24. Deb, M. L.; Baruah, B.; Bhuyan, P. J. Synthesis, 2008, 286-292.
25. Gu, R.; Van Snick, S.; Robeyns, K.; Van Meervelt, L.; Dehaen, W.
Org. Biomol. Chem. 2009, 7, 380-385.
4.2.3.3. 2,7,11,16-tetramethoxydibenzo[2,3;5,6]pyrrolizino[1,7-
bc]indolo[1,2,3-lm]carbazole (1c). Yellow microcrystals from
benzonitrile, 10% yield, sublime above 300°C. Calcd
C34H24N2O4: C (77.85 %), H (4.61 %), N (5.34 %). Found: C
(77.89 %), H (4.50 %), N (5.37 %).
4.2.3.4. 2,8,11,17-tetramethoxydibenzo[2,3;5,6]pyrrolizino[1,7-
bc]indolo[1,2,3-lm]carbazole (1d). Dark yellow microcrystals
with metallic luster from benzonitrile, 38% yield, sublime above
300°C. Calcd C34H24N2O4: C (77.85 %), H (4.61 %), N (5.34 %).
Found: C (77.99 %), H (4.55 %), N (5.38 %).
26. Deb, M. L.; Mazumder, S.; Baruah, B.; Bhuyan, P. J. Synthesis, 2010,
929-932.
4.2.3.5.
Dibenzo[2,3:5,6]pyrrolizino[1,7-bc]indolo[1,2,3-
acid (1e). Brownish
27. Deb, M. L.; Bhuyan, P. J. Tetrah. Lett. 2007, 48, 2159-2163.
28. Gaussian 09, Revision A.02,
lm]carbazole-2,11-dicarboxylic
Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.;
Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.;
Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.;
Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima,
T.;
Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, Jr., J. A.;
Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.;
Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.;
Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.;
Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.;
Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.;
Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.;
Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.;
Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.;
Farkas, O.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.;
Fox, D. J. Gaussian, Inc., Wallingford CT, 2009.
microcrystals, 88% yield. Decompose above 300°C. Calcd for
C32H16N2O4: C (78.04 %), H (3.27 %), N (5.69 %). Found: C
(78.15 %), H (3.22 %), N (5.61 %). 1H NMR (DMSO-d6 +
TBAOH): δ = 0.94 (t, 12H, CH3), 1.31 (m, 8H, CH2), 1.57 (m,
3
8H, CH2), 3.16 (m, 8H, CH2), 6.93 (d, J = 8.29, 1H, CH), 7.02
(td, 3J = 8.28, 4J = 1.25 Hz, 2H, CH), 7.08 (d, 3J = 8.28, 1H, CH),
7.35 (dd, 3J = 8.37, 4J = 1.25 Hz, 1H, CH), 7.62 (dd, 3J = 8.35, 4J
= 1.22, 1H, CH), 7.69 (dd, 3J = 8.39, 4J = 1.21, 1H, CH), 7.78 (td,
4
4
3J = 8.28, J = 1.25 Hz, 2H, CH), 8.38 (d, J = 1.25, 1H, CH),
3
3
8.55 (d, J = 7.90, 1H, CH), 8.75 (d, J = 7.90, 2H, CH), 9.18(d,
4J = 1.25, 1H, CH).
Acknowledgments
This work was supported by ANR (French Agency for
National Research), project NEM, ANR-09-BLAN-0107. We
thank the French Ministry of Education and Ecole Doctorale des
Sciences Chimiques (ED 250, Marseille) for a fellowship to M.R.
29. Xu, C.; Webb, W. W. J. Opt. Soc. Am. B. 1996, 13, 481-491.
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