Synthesis and Liquid Crystalline Self-Assembly of Concave Diindoles with a Hydropentalene Core

Article abstract of DOI:10.1002/ejoc.202001656

Fischer indole reaction of Weiss diketone with 4-bromophenylhydrazine provided the 2,8-dibromo-hexahydropentaleno[2,1-b:5,4-b’]diindole key intermediate, which was converted to the target compounds by N-protection/Suzuki cross-coupling. Variation of prote

Full text of DOI:10.1002/ejoc.202001656

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Synthesis and Liquid Crystalline Self-Assembly of Concave
Diindoles with a Hydropentalene Core
[a]
[a]
[a]
[a]
[a]
Andrea Bühlmeyer, Philipp Ehni, Dustin Ullmann, Wolfgang Frey, Angelika Baro, and
[a]
Sabine Laschat*
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Fischer indole reaction of Weiss diketone with 4-bromophenyl-
hydrazine provided the 2,8-dibromo-hexahydropentaleno[2,1-
b:5,4-b’]diindole key intermediate, which was converted to the
target compounds by N-protection/Suzuki cross-coupling. Varia-
tion of protecting groups, mesogenic units, and their alkoxy
substitution gave calamitic diindole mesogens. Both N-protec-
tion and alkoxy chain influenced the mesomorphic properties
of phenyl diindoles. Among the differently N-protected deriva-
tives only ethylcarbamate-protected ones formed enantiotropic
mesophases. Mesophase range and type were controlled by the
chain lengths: chains�C12 gave nematic (N) phases, diindoles
with side chainsꢀC14 formed additional lower temperature
smectic (SmA) phases. Irrespective of the chain lengths 4’-
alkyloxybiphenyl diindoles formed N and SmA phases upon first
heating but tended to decomposition below their clearing
points. X-ray crystal structure analysis of bis(4’-decyloxy)
biphenyl diindole reveals that in the solid-state the folding
angle of the hydropentalene core caused an almost perpendic-
ular orientation of the two indole/biphenyl parts with respect
to each other.
Introduction
Indole derivatives are key building blocks for organic materials,
natural products, pharmaceuticals, agrochemicals, biopolymers,
and synthetic functional polymers. With respect to material
science
their
electron-rich
heteroaromatic
π-system,
fluorescence, hole conducting properties, and versatile func-
tionalization make them ideal candidates for dye-sensitized
solar cells, organic photovoltaics, organic light-emitting diodes,
[1]
and organic field-effect transistors. Regarding liquid crystalline
indole materials, most work has been carried out on indole-
containing discotic and dendrimeric liquid crystals. Typical
examples are the star-shaped triindoles 1 developed by
[
2]
[3]
Omenat, taper-shaped dendrons 2 reported by Percec, and
shape-persistent macrocycles published by Tanaka
(
3
[4]
Scheme 1).
In the majority of these cases, carbazole moieties were used
[5,6]
rather than the parent indoles.
Calamitic indoles (or
carbazoles) were only rarely explored. Marin disclosed a dimer
, where the two N-acetylindole moieties are connected via a
4
[7]
flexible triethylene glycol spacer. However, the phase type
could not be assigned due to the lack of XRD data. More
[a] Dr. A. Bühlmeyer, P. Ehni, D. Ullmann, Dr. W. Frey, Dr. A. Baro,
Prof. S. Laschat
Institut für Organische Chemie, Universität Stuttgart,
Pfaffenwaldring 55, 70569 Stuttgart, Germany
E-mail: sabine.laschat@oc.uni-stuttgart.de
https://www.ioc.uni-stuttgart.de/en/research/ak-laschat/
Supporting information for this article is available on the WWW under
https://doi.org/10.1002/ejoc.202001656
Scheme 1. Some selected liquid crystalline indole materials from the
literature.
©
2021 The Authors. European Journal of Organic Chemistry published by
Wiley-VCH GmbH. This is an open access article under the terms of the
Creative Commons Attribution Non-Commercial License, which permits use,
distribution and reproduction in any medium, provided the original work is
properly cited and is not used for commercial purposes.
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recently, a nematic carbazole-containing rigid oligomer was
reported by O’Neill.
promote mesophase formation. Furthermore, the concave
saturated hydropentalene spacer unit sterically shields the
indole moiety against sequential oxidation/polymerization re-
actions. In the current manuscript, we report the successful
realization of this design concept.
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[8]
[11]
This lack of information on liquid crystalline indole deriva-
tives might be due to the pronounced tendency of indoles
[1f]
towards oxidation and subsequent polymerization. In order to
avoid such complications and to tailor mesomorphic properties
by suitable functionalization, we chose the hexacyclic diindole
unit on the basis of unsubstituted compound 5, which was Results and Discussion
originally synthesized by Cook to obtain a fully conjugated
[9]
[10]
pentaleno[2,1-b:5,4-b’]diindole scaffold (Scheme 2).
Synthesis of Diindoles
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We aimed at compound 6 carrying mesogenic units. The
protecting groups at the indole nitrogen were intended to
stabilize the indole against oxidative decomposition and to
The synthesis of diindoles 6 commenced with a twofold Fischer
[12]
indole synthesis of Weiss diketone 7 with 4-bromophenylhy-
drazine hydrochloride 8 (Scheme 3). The initial protocol by
[
13]
Kotha
utilizing thionyl chloride in EtOH at 70°C for 24 h
provided dibromodiindole 9 in only 29%, and thus, other acids
and conditions were tested (Table S1). According to a modified
Fischer indole synthesis by Chandrasekhar using the solid
acid Amberlite® IR120, a cation exchange resin, Weiss diketone
[14]
7
and bromophenylhydrazine 8 finally were reacted in refluxing
EtOH for 12 h, then the resin was filtered off and derivative 9
was isolated in 49% after workup (Scheme 3). It should be
emphasized that a two-step protocol towards 9 via Fischer
indole synthesis using phenylhydrazine, followed by bromina-
tion of the resulting diindole was not amenable (Table S2,
Supporting Information), as was previously reported for the
bromination of cyclopenta[b]indoles with standard bromination
[15]
reagents.
Scheme 2. Envisaged hexacyclic diindole moiety 6.
Scheme 3. Synthesis of the diindole derivatives Ph-6 via the two routes A and B.
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The target compounds 6 were accessible from dibromodiin-
dole 9 either by running first the Suzuki coupling and
subsequently the N-protection (route A) or the reversed order
route B). The Suzuki coupling of dibromodiindole 9 with 4-
dodecyloxy)phenylboronic acid 10c proceeded without any
In addition, the aspect (lengths to breadths) ratio was
increased by attaching 4’-(alkoxy)-1,1’-biphenyl units to the
diindole core 12a, and the resulting target compounds Biph-
6a–d were isolated in 23–43% yield (Scheme 4).
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(
(
Fortunately, single crystals of diethyl 2,8-bis(4’-decyloxy-1,1’-
biphenyl)-tetrahydropentaleno[2,1-b:5,4-b’]diindole-5,11-dicar-
boxylate Biph-6a could be obtained, which enabled an X-ray
event and the resulting diindole 11 was isolated in 64% (route
A). Compound 11 was then used as a key intermediate to
introduce the N-protecting groups. The reaction of 11 with
ethyl chloroformate and KOH in DMF at 0°C and warming to
[19]
crystal structure determination (Figure 1).
Biph-6a crystallized with one molecule in the asymmetric
unit of the centrosymmetric, triclinic space group P-1. Both
terminal aliphatic chains are disordered (Figure S1). The central
hydropentalene core features a folding angle between the 5-
membered ring systems of 64.2(1)°, resulting in a nearly
perpendicular orientation of the indole and biphenyl moieties
(average about 75°). Both biphenyl units are out of plane in
their orientation, but with clearly different values (24.0(3)° and
11.1(3)°, respectively). The packing diagram of the cell plot
(Figure 1b) shows only a slight interdigitation of the molecules.
This observation is supported by the disordered behavior of the
aliphatic chains which underlines no clear orientation of them
to each other. Nevertheless, we observe three types of weak
intermolecular interactions, namely π-π interactions of the
indole moieties characterized representatively by a N1-C13
distance of 3.40 Å, aliphatic-π interactions which have more
electrostatic character, for example, between aliphatic C51 and
biphenyl C38 with a distance of 3.41 Å (the distance of the
donor H51A and the acceptor C38 is 2.81 Å and the relevant
angle C51-H51A···C28 is 120°), and last a type of weak hydro-
room temperature over 16 h gave diethyl diindoledicarboxylate
1
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Ph-6c in 74%. Treatment of 11 with Boc O in the presence of
2
[16]
DMAP in THF following a method by Zaimoku provided the
Boc-protected diindole Ph-6g albeit with a disappointing yield
of 36%. Alkylation with 1-iodopropane and 1-bromododecane,
respectively, yielded the N-alkylated products Ph-6j and Ph-6k
1
(
R =C H and C H ) in 80% and 38%.
3
7
12 25
Following route B key intermediate 9 was submitted first to
the N-protection. The yields of the N-protected dibromodiin-
doles 12 ranged between 80% and 88%, except for the Z-
protected derivative 12d, which was isolated in only 35%
(
Scheme 3). The subsequent Suzuki cross-coupling of com-
pounds 12a–e with 4-(dodecyloxy)phenylboronic acid 10c
again turned out to be a certain bottleneck, providing the
respective target diindoles Ph-6c,f–i in 10–45% yield. In order
to vary the alkoxy chain lengths, N-protected dibromodiindole
2a was coupled with 4-(alkoxy)phenylboronic acids 10a–e to
yield the diindoles Ph-6a–e in 22–45% (Scheme 3).
1
Furthermore, we aimed to increase the volume requirement
of the side chains. For this purpose, 12a was reacted with 3,4-
bis(dodecyloxy)- and 3,4,5-tris(dodecyloxy) phenylboronic
phobic intermolecular interactions between the aliphatic chains
characterized by a C57···C61 distance of 3.57 Å. The distance of
the donor H57B to the acceptor C61 is 2.77 Å and the relevant
angle C57-H17B···C61 is 138°.
[17,18]
acid
substituted diindoles Ph-6l and Ph-6m in 51% and 43% yield
Scheme 4).
to give the respective tetra- and hexa-dodecyloxy-
(
Mesomorphic Properties of Diindoles
The liquid crystalline behavior of the synthesized diindoles 6
was first investigated by differential scanning calorimetry (DSC).
Selected DSC curves are given in Figure 2. Among the differ-
ently N-protected diindoles only diethyl diindoledicarboxylate
Ph-6c formed enantiotropic mesophases, whereas the other
derivatives were either monotropic (Ph-6f,g) or non-mesomor-
phic (Ph-6h–k). The series of compounds Ph-6a–e carrying
alkyloxy substituents of various chain lengths showed enantio-
tropic mesomorphism. The results of the DSC measurements
are summarized in Table 1 and visualized in Figure 4 for
comparison.
The first heating curve of Ph-6c showed an endothermal
melting transition at 184°C and a hardly visible weak clearing
transition at 203°C (Figure 2a). Upon first cooling, the isotropic-
to-mesophase transition appeared at 206°C, while the M!Cr
2
transition at 110°C showed a pronounced hysteresis due to
supercooling. In addition, a Cr !Cr transition at 100°C was
2
1
detected. The phase behavior during subsequent heating/
cooling cycles was fully reproducible. Under the polarizing
optical microscope (POM) Schlieren textures were observed at
Scheme 4. Synthesis of diindole derivatives Ph-6l,m and Biph-6.
2
06°C (Figure 3a), which are indicative of a nematic (N) phase.
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Figure 1. a) Structure of Biph-6a in the solid-state (central hydropentalene core in grey, H atoms omitted for clarity). b) Packing diagram of the unit cell (for
clarity top view orientation to one side of the π-systems); and c) a further view on the orientation of two molecules revealing interactions between the alkyl
chain and biphenyl unit.
À 1
Table 1. Phase transition temperatures [°C] and enthalpies ΔH [kJmol ] of diindoles Ph-6a–e and Biph-6a–d upon second heating (H) and cooling (C) (rate
À 1 [a,b]
10 Kmin ).
Compd
Phase
T (ΔH)
Phase
T (ΔH)
Phase
T (ΔH)
Phase
Ph-6a
Cr
Cr
Cr
209 (44.5)
162 (38.5)
200 (62.1)
151 (37.6)
183 (59.7)
110 (40.6)
174 (59.0)
103 (39.4)
166 (56.6)
97 (17.4)
203 (30.2)
193 (16.1)
168 (16.3)
154 (19.2)
N
N
N
N
N
N
N
N
N
N
N
N
N
N
250 (1.0)
249 (1.2)
230 (1.1)
230 (1.1)
203 (1.0)
206 (1.2)
200 (0.9)
200 (1.0)
185 (0.8)
186 (1.0)
338
I
I
I
I
I
I
I
I
H
C
H
C
H
C
H
C
H
C
H
H
H
H
Ph-6b
Ph-6c
Ph-6d
Ph-6e
[
c]
Cr
Cr
Cr
Cr
Cr
Cr
Cr
Cr
Cr
Cr
Cr
[d]
SmA
SmA
SmA
SmA
183 (0.2)
185 (0.3)
180 (0.8)
181 (0.1)
I
I
Biph-6a
Biph-6b
Biph-6c
Biph-6d
I (dec.)
I (dec.)
I (dec.)
I (dec.)
SmA
SmA
SmA
207 (60.1)
193 (33.9)
196 (29.3)
303
301
304
[
20]
[
a] The onset of the heat flow peaks was used for the determination of the corresponding transition temperature. Phases observed: Cr crystalline; N
nematic; SmA smectic A; I isotropic. [b] The phase transitions of compounds Biph-6a-Biph-6d were determined upon first heating due to decomposition in
st
subsequent cooling/heating cycles. [c] 1 heating curve was taken; an additional Cr-to-Cr transition at 132°C. [d] Additional Cr-to-Cr transition at 104°C.
Phenyl diindoles Ph-6g,f suffered from thermal decomposi-
tion already during first heating and were not further inves-
tigated (Figure S3, Figure S4, and Figure S19, Supporting In-
formation).
peripheral tetradecyloxy and hexadecyloxy substituents formed
additional mesophases at lower temperatures (Table 1). The
corresponding phase transition was hardly visible in the DSC
curves but could be detected under the POM. An exemplary
DSC curve is shown in Figure 2b for Ph-6e where an
A comparison of the alkoxy chain lengths reveals that the
short-chain members Ph-6a–c with C , C and C12 chains
endothermal melting transition at 166°C, an endothermal M !
8
10,
1
displayed only nematic phases, while diindoles Ph-6d,e with
M transition at 180°C and a low-intensity clearing transition at
2
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Figure 3. Textures as seen between crossed polarizers upon cooling from
the isotropic liquid. (a) Nematic droplets and Schlieren texture of Ph-6c at
2
06°C, (b) Schlieren texture of Ph-6d at 198°C, (c) fan-shaped texture of Ph-
6
d at 178°C, (d) Schlieren texture of Ph-6e at 183°C, (e) fan-shaped texture
of Ph-6e at 175°C, and (f) Schlieren texture of Biph-6a at 263°C (cooling
À 1
rate 5 Kmin ).
melting and clearing points decreased with increasing chain
lengths, resulting in nematic phase widths of 41 K (for C ) to 5 K
8
(
for C ). The phase widths of the SmA phase, however,
16
increased slightly from 9 K (for C ) to 14 K (for C ). In the
1
4
16
cooling cycle phase widths of the nematic phase for C -C
8
12
diindoles Ph-6a–c increased significantly to 87 K, 97 K, and
6 K, respectively, due to supercooling effects. For the C14 and
9
C16 diindoles Ph-6d and Ph-6e the same effects could be
noticed for the SmA mesophases, leading to large phase widths
of 82 K and 84 K, respectively.
Figure 2. DSC curves of (a) phenyl diindole derivatives Ph-6c, (b) Ph-6e, and
st
nd
(
c) 4’-(decyloxy)biphenyl diindole Biph-6a (c). (1.H, 2.H, 3.H relates to 1 , 2 ,
Whereas phenyl diindoles Ph-6l,m with 4 or 6 dodecyloxy
side chains were non-mesomorphic, 4’-alkoxybiphenyl-substi-
tuted diindoles Biph-6a–d were liquid crystalline. The DSC
curve of Biph-6a, for example, revealed melting at 203°C and a
clearing point at 338°C upon first heating (Figure 2c and
rd
st
nd
rd
and 3 heating; 1.C, 2.C, 3.C relates to 1 , 2 , and 3 cooling).
1
85°C upon heating were visible. Upon cooling the isotropic
liquid-to-mesophase transition appeared at 186°C, the M !M
Table 1). In subsequent heating/cooling scans no further
transitions were detectable due to thermal decomposition, as
was confirmed by thermogravimetric analysis (Figure S25).
Irrespective of the chain lengths, the biphenyls Biph-6a–d were
thermally stable up to 280°C. Upon further heating, decom-
2
1
transition at 181°C, and the crystallization peak at 97°C with a
large hysteresis.
Under the POM a Schlieren texture was observed for Ph-6d
at 198°C, which persisted upon cooling until 178°C, when a
fan-shaped texture appeared, suggesting a smectic A (SmA)
phase (Figure 3b, Figure 3c). Figure 3d, Figure 3e display the
Schlieren and fan-shaped textures of diindole Ph-6e at 183°C
and 175°C, respectively.
position was accompanied by loss of mass. As the clearing
points were located above the decomposition temperature,
further characterization was done during the first heating.
Figure 4b revealed very broad nematic phase widths for
Biph-6a–d ranging from 77 K (for C ) to 84 K (for C ).
As shown in Figure 4a, the mesophase ranges in the series
of Ph-6a–e depended on the alkoxy chain lengths. Both the
1
0
16
Compound Biph-6a only displayed a nematic phase until
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Table 2. XRD data of diindoles Ph-6d,e and Biph-6b–d.
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Compound
Phase
SmA
T [°C]
d [Å]
Miller Indices
Ph-6d
161
40.78
4.47
(001)
Halo
(001)
Halo
(001)
Halo
(001)
Halo
(001)
Halo
Ph-6e
SmA
SmA
SmA
SmA
159
220
220
244
42.21
4.55
Biph-6b
Biph-6c
Biph-6d
46.13
4.25
49.69
4.50
53.02
1
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5
5
5
5
5
5
5
4.43
sharp (001) reflection in the small-angle range and a diffuse
signal (halo) in the wide-angle section (Figure 5b and Table 2).
As seen in Figure 6a for diindole Ph-6d, temperature-
dependent SAXS measurements of the (001) reflection showed
a decrease of the layer distance d with increasing temperature,
[22]
which is typical for SmA phases. Similar results were obtained
for the C16 diindole Ph-6e (Figures S32–S34). The experimentally
determined layer distance d001 =39.46 Å at 200°C for Ph-6d is
somewhat smaller than the calculated fully stretched all-trans
[23]
molecular length of 53.3 Å. Usually, interdigitation of alkyl
chains is observed in lamellar phases with bilayers and is rather
uncommon in monolayers due to lack of space. However, due
to their nature, the cores of the diindoles take up a lot of space,
which creates free volume that can be filled by interdigitation
of the alkyl chains. Assuming fully interdigitated alkyl chains
Figure 4. Mesophase widths of (a) phenyl diindoles Ph-6a–e obtained by
DSC upon second heating and cooling, and (b) of Biph-6a-d upon first
heating until the decomposition temperature (*) (heating rate 10 Kmin ).
À 1
(
Figure 6b), a smectic layer would thus consist of the length of
the core (for Ph-6d: 19.0 Å) and the length of the alkyl chain
for Ph-6d: 18.6 Å), resulting in a total length of dcalc =37.6 Å,
which is close to the experimentally determined value of d001
(
decomposition, which could be due to the shorter length.
Diindoles with chain lengths C -C showed additional SmA
=
39.46 Å for Ph-6d. This deviation from the d001-value can be
explained by differences in temperature or discrepancies in
calculated molecule shape to the real shape of the diindoles.
Experimental layer distances for the C16 compound Ph-6e (d=
42.21 Å at 159°C) show similar behavior in comparison with Ph-
1
2
16
phases of 14–42 K width. With increasing chain lengths, the
nematic-to-SmA transition is shifted towards lower temperature
and so the more structured low-temperature SmA phase is
observed to a higher degree. The extension of the aspect ratio
has increased the stability of the nematic phase but at the
expense of thermal decomposition of the compounds.
6d.
XRD studies of the biphenyl diindole series Biph-6a–d
agreed well with the results of the liquid crystalline phenyl
diindoles Ph-6. For example, the WAXS diffractogram of
derivative Biph-6c in the low-temperature mesophase at 200°C
revealed a distinct (001) layer reflex at small angles and in the
wide-angle section a broad halo at 4.50 Å (Figure 5c). Temper-
ature-dependent XRD measurements of the (001) reflections
further supported the SmA assignment and provided layer
distances d001 of 46.19 Å (n=12, 220°C), 49.64 Å (n=14, 218°C)
and 52.76 Å (n=16, 220°C) for the larger biphenyl diindoles
Biph-6b–d with different chain lengths, which is in good
agreement to the SmA packing model provided in Figure 6b.
The WAXS diffraction pattern of Biph-6c in the high-temper-
ature mesophase resembled that of the N phase of Ph-6a
(Figure 5a), displaying two diffuse reflections in the small-angle
region and the arch-like halo perpendicular to the reflections.
While the X-ray crystal structure of biphenyl diindole Biph-
6a revealed a partial overlap of the alkyl side chains and
aromatic units in the crystalline solid, a nematic phase showing
Under the POM a Schlieren texture was observed for Biph-
6
a at 263°C (Figure 3f). The higher homolog Biph-6b displayed
fan-shaped textures, whereas diindoles Biph-6c,d with C14 and
C16 side chains showed focal-conic defects, indicating a SmA
phase (Figures S13–S15).
X-Ray diffraction (XRD) experiments gave more insight into
the phase geometries of the liquid crystalline diindoles. The
XRD data are summarized in Table 2. The wide-angle X-ray
scattering profile and the diffraction pattern of an oriented
nematic phase of Ph-6a at 230°C are given in Figure 5a.
The reflection in the small-angle region is broadened due to
the lack of a positional long-range order in the N phase. In the
corresponding diffraction pattern, two diffuse peaks in the
small-angle and two perpendicularly oriented (induced by
magnetic preorientation of the sample) arch-shaped broad
reflexes in the wide-angle regime are visible, which are
[21]
characteristic of a nematic phase.
In contrast, the WAXS
profile of diindole Ph-6d in the SmA phase at 161°C revealed a
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1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
Figure 5. Wide-angle X-ray scattering (WAXS) profiles of (a) Ph-6a in the
nematic (N) phase at 230 C, (b) Ph-6d in the SmA phase at 161 C, and (c)
°
°
Biph-6c in the SmA phase at 200
pattern.
°
C. Inset: the corresponding diffraction
only 1D long-range orientational order was detected by XRD for
this particular derivative. Upon increasing the chain lengths in
the biphenyl series, van der Waals interactions between the
side chains increased, resulting in increased nanosegregation
and formation of lamellar SmA phases in addition to the N
phases, as was shown by XRD studies for Biph-6b-Biph-6d. In
Figure 6. (a) Temperature-dependent SAXS layer distances d001 for phenyl
diindole Ph-6d and (b) schematic illustration of the proposed packing of Ph-
6d in the SmA phase.
contrast, increasing the number of side chains in the phenyl Conclusion
series resulted in a significant decrease of the melting point for
Ph-6m with six peripheral side chains while simultaneously
suppressing mesophase formation. This is probably due to the
large difference in volume requirements of the core unit and
the side chains, which do not allow self-assembly into a stable
mesophase.
A new family of indole-containing rigid, concave-shaped
calamitic liquid crystals was prepared by a twofold Fischer
indole synthesis as the key step. From a practical point of view,
it was found advantageous to convert the dibromodiindole
intermediate 9 into the target diindoles Ph-6 and Biph-6 via
sequential N-protection / Suzuki cross-coupling rather than
using the reversed sequence.
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The N-protecting group had a major impact on the liquid
crystalline self-assembly. Among all tested protecting groups
Boc, CO Me, CO Et, Z, Me, n-propyl, n-dodecyl, Ts) only the
ethylcarbamate led to stable mesophases and reproducible
phase behavior.
form, strongly acidic) was added, and the reaction mixture stirred at
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
0°C for 16 h. After cooling to room temperature, the resin was
filtered off, washed with EtOAc and the filtrate was concentrated
under vacuum. The resulting solid was dissolved in EtOAc, the
(
2
2
organic layer washed with H O, dried (MgSO ), and the solvent was
2
4
removed under vacuum. The crude product was purified by column
Chain length variation in the series of phenyl diindoles Ph-
chromatography on silica (gradient hexanes/EtOAc 50:1!3:1) to
give 9 (1.46 g, 3.31 mmol, 46%) as a yellow solid. M.p. 256–257
°
C;
a
6
a–e (C -C ) resulted in destabilization of the nematic phase
8
16
1
H NMR (500 MHz, [D ]DMSO): δ=2.91–2.98 (m, 2H; 6-H , 12-H ),
with increasing chain lengths, whereas SmA phases were
stabilized. An increase of the total number of alkoxy substitu-
ents from 2 to 4 or 6 led to the loss of mesophases.
On the other hand, an increase of the aspect ratio by
extending the hexacyclic diindole core with peripheral alkyloxy-
biphenyl instead of alkyloxyphenyl significantly stabilized the
nematic phase. However, in agreement with the old saying
6
a
3.24–3.32 (m, 2H; 6-H , 12-H ), 4.38–4.43 (m, 2H; 6a-H, 12a-H), 7.08
b
b
(dd, J=8.8, 1.9 Hz, 2H; 3-H, 9-H), 7.22 (d, J=8.8, 2H; 4-H, 10-H), 7.63
13
(
d, J=1.9 Hz, 2H; 1-H, 7-H), 10.98 ppm (s, 2H, NH); C NMR
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
(
125 MHz, [D ]DMSO): δ=30.8 (C-6, C-12), 46.9 (C-6a, C-12a), 111.2
6
(C-2, C-8), 113.6 (C-4, C-10), 119.7 (C-1, C-7), 119.8 (C-6b, C-12b),
122.0 (C-3, C-9), 125.3 (C-6c, C-12c), 139.8 (C-4a, C-10a), 144.3 ppm
(
C-5a, C-11a). FT-IR (ATR): ~n =3441 (w), 3068 (w), 2931 (w), 2844 (w),
1724 (w), 1606 (w), 1572 (w), 1466 (w), 1425 (s), 1349 (w), 1282 (s),
“
every magic comes with a price” the increase of the aspect
1221 (w), 1148 (w), 1041 (w), 976 (w), 924 (w), 863 (s), 837 (w), 796
ratio of Biph-6 led to clearing points above the decomposition
temperature of 280°C. From the XRD results a packing model
for the SmA phase was proposed, where the S-shaped rigid
cores arrange themselves in an interdigitated monolayer, which
is in agreement with the solid-state packing of Biph-6a.
Our results reveal that the steric isolation of the two indole
moieties by a saturated hydropentalene core together with the
choice of suitable carbamate protecting group indeed lead to
stable calamitic indoles suitable for further exploration as
organic soft matter materials.
À 1
(
s), 743 (w), 693 (w), 641 (w), 582 (s) cm ; MS (ESI): m/z=438.9
À
À
[MÀ H] , 324.9; HRMS (ESI): m/z calcd for C H Br N -H : 438.9440
2
0
14
2
2
À
À
[MÀ H] , found: 438.9435 [MÀ H] .
Diethyl (6aSR,12aSR)-2,8-dibromo-6,6a,12,12a-tetrahydropenta-
leno[2,1-b:5,4-b’]diindole-5,11-dicarboxylate (12a): To a solution
of 9 (1.22 g, 2.74 mmol) in abs. DMF (25 mL) with powdered KOH
(774 mg, 13.8 mmol) ethyl chloroformate (7.88 mL, 898 mg,
8
.28 mmol) was slowly added at 0°C and the reaction mixture was
then stirred at room temperature for 16 h. The reaction mixture
was diluted with H O (200 mL), and the resulting solid was filtered
2
off, washed with EtOAc and dried to give 12a (1.45 g, 2.26 mmol,
8
2%) as a colorless solid. M.p. 335°C (dec.); due to poor solubility
1
2a could not be characterized by NMR spectroscopy; FT-IR (ATR):
~
n=3069 (w), 2982 (w), 2919 (w), 2852 (w), 1743 (s), 1728 (s), 1609
Experimental Section
(w), 1591 (w), 1564 (w), 1476 (w), 1458 (w), 1438 (s), 1403 (s), 1376
General. All chemicals were used as purchased. Anhydrous solvents
were dried and distilled under nitrogen atmosphere prior to use. All
reactions were carried out under a nitrogen atmosphere with
Schlenk-type glassware unless otherwise stated. NMR spectra were
recorded on Bruker Avance 400, 500 or 700 MHz instruments. All
chemical shifts (δ) are given in ppm and are referenced to
tetramethylsilane as an internal standard unless otherwise stated.
Assignment of the resonances was supported by 2D experiments
(s), 1346 (s), 1318 (s), 1289 (w), 1274 (w), 1235 (w), 1213 (s), 1162
(w), 1125 (s), 1055 (s), 960 (w), 935 (w), 884 (w), 871 (w), 851 (w),
8
4
4
13 (s), 786 (w), 762 (s), 744 (w), 707 (s), 653 (w), 577 (w), 499 (w),
À 1
+
54 (w), 426 (w) cm . MS (EI): m/z=586.0 [M] (100), 508.1 (15),
41.0 (4), 360.0 (9), 279.1 (9) 79.9 (6), 44.0 (4); HRMS (EI): m/z calcd
+
+
+
for C H Br N O : 583.9946 [M] , found: 583.9942 [M] .
2
6
22
2
2
4
General Procedure for the Preparation of Carbamate-protected
2
Diindoles (GP1): To a solution of 9 (430 μmol) in abs. CH Cl2
(COSY and HMBC). IR spectra were recorded on a Bruker Vektor 22
(
20 mL) with powdered NaOH (2.15 mmol) and Bu NBr (43.0 μmol)
instrument equipped with a MKII Golden Gate Single Reflection
Diamond ATR. MS and HRMS were measured on a Bruker micro-
TOF-Q spectrometer with electrospray ionization (ESI) or on a
Finnigan Varian MAT95 spectrometer with electron ionization (EI).
GC-MS was performed on an Agilent Technologies 6890N Network
GC system equipped with an Agilent 5973 Network Mass Selective
Detector. An Olympus BX50 combined with a Linkam TP93 central
controller was used for polarizing optical microscopy (POM).
Differential scanning calorimetry (DSC) was carried out on a Mettler
4
the appropriate formate (1.29 mmol) was added and the reaction
mixture stirred at room temperature for 16 h. The formed
suspension was mixed with H O (3×20 mL) and the resulting solid
2
was filtered off, washed with Et O (2×20 mL) and dried.
2
Dimethyl (6aSR,12aSR)-2,8-dibromo-6,6a,12,12a-tetrahydropen-
taleno[2,1-b:5,4-b’]diindole-5,11-dicarboxylate (12b): According
to GP1, from 9 (190 mg, 430 mmol), NaOH (86.0 mg, 2.15 mmol),
Bu NBr (14.0 mg, 43.0 mmol), methyl formate (0.80 mL, 77.0 mg,
e
4
Toledo DSC822 and X-ray diffraction (XRD) measurements on a
1
>
.29 mmol); yield: 210 mg, 376 mmol, 88%, colorless solid; m.p.
350°C; due to poor solubility 12b could not be characterized by
Bruker AXS Nanostar C with ceramic tube generator (1500 W) and
cross-coupled Goebel mirrors (monochromatic CuK,α1 radiation,
NMR spectroscopy; FT-IR (ATR): ~n =3333 (w), 3108 (w), 2916 (s),
2848 (s), 1732 (s), 1613 (w), 1593 (w), 1562 (w), 1462 (s), 1439 (s),
1398 (w), 1368 (s), 1336 (w), 1319 (s), 1284 (w), 1258 (w), 1235 (w),
1.5405 Å). Diffraction patterns were measured with a Bruker HI-
STAR detector and were calibrated using a diffraction pattern of
silver behenate at room temperature. The diffraction patterns were
analyzed with Datasqueeze and Origin. Flash chromatography was
performed on silica gel, grain size 40–63 μm (Fluka), and aluminium
sheets precoated with silica gel 60 F254 (Merck) were used for thin-
layer chromatography (TLC).
1
213 (s), 1164 (w), 1127 (s), 1089 (w), 1049 (s), 999 (w), 952 (w), 937
(
w), 879 (w), 862 (w), 812 (s), 784 (w), 759 (s), 745 (w), 729 (w), 708
À 1
(s), 660 (w), 579 (w), 542 (w), 499 (w), 433 (w) cm ; MS (ESI): m/z=
+
5
80.95 [M+Na] , 393.30, 301.14; HRMS (ESI): m/z calcd for
+
+
+
C H Br N O : 578.9526 [M+Na] , found: 578.9520 [M+Na] .
2
4
18
2
2
4
(
6aSR,12aSR)-2,8-Dibromo-5,6,6a,11,12,12a-hexahydropentaleno
Di-tert-butyl (6aSR,12aSR)-2,8-dibromo-6,6a,12,12a-tetrahydro-
pentaleno[2,1-b:5,4-b’]diindole-5,11-dicarboxylate (12c): To a sol-
ution of 9 (125 mg, 283 μmol) in abs. THF (50 mL) di-tert-butyl
dicarbonate (148 mg, 676 μmol) and 4-dimethylaminopyridine
[2,1-b:5,4-b’]diindole (9): To a solution of ketone 7 (1.00 g,
7.24 mmol) and 4-bromophenylhydrazine hydrochloride 8 (3.80 g,
17.0 mmol) in abs. EtOH (70 mL) Amberlite® IR 120 (10 g; hydrogen
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+
+
(
3.00 mg, 28.3 μmol) were added and the reaction mixture was
(APCI): m/z calcd for C H Br N O S +H : 748.9773 [M+H] ,
found: 748.978 [M+H] .
3
4
26
2
2
4 2
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
+
stirred at room temperature for 5 h. The reaction mixture was then
washed with a satd solution of NaHCO (15 mL) and extracted with
EtOAc (3×20 mL). The combined organic layers were washed with
3
General Procedure for the Preparation of Alkoxy-protected
Diindoles (GP2): To a solution of the respective diindole (351 μmol)
in abs. DMF (5 mL) with powdered KOH (49.0 mg, 876 μmol) the
appropriate 1-bromoalkane (876 μmol) was added and the reaction
mixture was stirred at room temperature for 16 h. The reaction
H O (3×20 mL), dried (MgSO ), and the solvent was removed under
2
4
vacuum. The crude product was purified by column chromatog-
raphy on silica with hexanes/EtOAc (5:1) to give 12c (147 mg, 228
1
mmol, 81%) as a colorless solid; m.p. 236°C; H NMR (700 MHz,
mixture was washed with H
O (15 mL), and extracted with CH Cl
2
2 2
CDCl ): δ=1.62 (s, 18H; CH ), 3.21–3.31 (m, 2H; 6-H , 12-H ), 3.44–
3
3
a
a
(
3×20 mL). The combined organic layers were dried (MgSO ) and
4
3.54 (m, 2H; 6-H , 12-H ), 4.30–4.52 (m, 2H; 6a-H, 12a-H), 7.32 (dd,
b
b
the solvent was removed under vacuum. The crude products were
J=8.8, 1.9 Hz, 2H; 3-H, 9-H), 7.59 (d, J=1.9 Hz, 2H; 1-H, 7-H),
13
either recrystallized from Et
2
O/EtOAc or purified by column
7
.98 ppm (d, J=8.8 Hz, 2H; 4-H, 10-H); C NMR (176 MHz, CDCl3):
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
chromatography on silica gel.
δ=28.2 (CH ), 33.9 (C-6, C-12), 45.7 (C-6a, C-12a), 84.0 (C(CH ) ),
3
3 3
1
1
16.1 (C-2, C-8), 117.4 (C-4, C-10), 120.8 (C-1, C-7), 125.3 (C-6b, C-
2b), 125.8 (C-3, C-9), 127.5 (C-6c, C-12c), 139.0 (C-4a, C-10a), 143.3
(
6aSR,12aSR)-5,11-Dipropyl-2,8-bis(4-dodecyloxyphenyl)-
5
6
6
,6,6a,11,12,12a-hexahydropentaleno[2,1-b:5,4-b’]diindole (Ph-
j): According to GP2, from 11 (100 mg, 124 mmol), KOH (35.0 mg,
21 mmol), 1-bromopropane (0.60 mL, 106 mg, 621 mmol), column
(
C-5a, C-11a), 149.4 ppm (NCOO); FT-IR (ATR): ~n =3005 (w), 2975 (w),
2927 (w), 2856 (w), 1728 (s), 1612 (w), 1593 (w), 1561 (w), 1474 (w),
1458 (w), 1433 (w), 1402 (w), 1391 (w), 1365 (s), 1335 (w), 1319 (w),
chromatography with CH Cl /hexanes (1:5); yield: 88.0 mg, 98.9
2
2
1
1
1
272 (w), 1256 (w), 1233 (w), 1216 (w), 1158 (w), 1123 (s), 1054 (w),
027 (w), 933 (w), 908 (w), 881 (w), 856 (w), 837 (w), 814 (w), 806
°
mmol, 80%, colorless solid, m.p. 167 C; H NMR (700 MHz, CDCl
δ=0.89 (t, J=7.3 Hz, 12H; CH ), 1.24–1.41 (m, 32H; CH ), 1.45–1.52
m, 4H; CH ), 1.71–1.85 (m, 8H; CH ), 3.10–3.18 (m, 2H; 6-H , 12-H ),
):
3
3
2
(
(
w), 767 (w), 733 (w), 703 (w), 674 (w), 650 (w), 578 (w), 498 (w), 462
(
2
2
a
a
À 1
+
w), 426 (w) cm ; MS (ESI): m/z=663.45 [M+Na] , 597.4, 447.34,
91.28, 371.31, 333.16, 305.13; HRMS (ESI): m/z calcd for
3
6
.29–3.39 (m, 2H; 6-H , 12-H ), 3.81–3.97 (m, 4H; NCH ), 4.01 (t, J=
b
b
2
3
.7 Hz, 4H; OCH ), 4.58–4.66 (m, 2H; 6a-H, 12a-H), 6.98 (d, J=8.6 Hz,
2
+
+
C H Br N O +Na : 663.0465 [M+Na] , found: 663.0468 [M+
3
0
30
2
2
4
4H; 3’-H), 7.24–7.27 (m, 2H; 3-H, 9-H), 7.30 (d, J=8.5 Hz, 2H; 1-H, 7-
H), 7.59 (d, J=8.7 Hz, 4H; 2’-H), 7.67–7.72 ppm (m, 2H; 4-H, 10-H);
+
Na] .
1
3
C NMR (176 MHz, CDCl ): δ=11.6 (NCH CH CH ), 14.1 (CH ), 22.7,
3 2 2 3 3
Dibenzyl (6aSR,12aSR)-2,8-dibromo-6,6a,12,12a-tetrahydropenta-
leno[2,1-b:5,4-b’]diindole-5,11-dicarboxylate (12d): According to
2
4
3.6, 26.1, 29.4, 29.4, 29.6, 29.7, 30.2, 31.0 (CH ), 31.9 (C-6, C-12),
2
6.5 (NCH ), 47.4 (C-6a, C-12a), 68.1 (OCH ), 109.9 (C-3, C-9), 114.7
2
2
GP1, from 9 (130 mg, 294 mmol), NaOH (30.0 mg, 747 mmol), Bu
NBr
4
(
(
C-3’), 116.2 (C-4, C-10), 119.3 (C-6b, C-12b), 120.0 (C-1, C-7), 124.3
C-6c, C-12c), 128.2 (C-2’), 132.1 (C-2, C-8), 135.3 (C-1’), 140.4 (C-4a,
(7.00 mg, 20.6 mmol), benzyl chloroformate (1.00 mL, 120 mg, 705
mmol), yield: 66.0 mg, 92.9 mmol, 32%, colorless solid; m.p. 305°C;
due to poor solubility 12d could not be characterized by NMR
spectroscopy; FT-IR (ATR): ~n =3066 (w), 3031 (w), 2936 (w), 2862
C-10a), 145.2 (C-5a, C-11a), 157.9 ppm (C-4’); FT-IR (ATR): n=3037
~
(w), 2954 (w), 2919 (s), 2851 (s), 1609 (w), 1575 (w), 1516 (s), 1467
(
(
7
8
C
s), 1432 (w), 1358 (w), 1324 (w), 1302 (w), 1272 (s), 1245 (s), 1176
(
w), 1732 (s), 1614 (w), 1598 (w), 1566 (w), 1500 (w), 1456 (w), 1443
w), 1127 (w), 1109 (w), 1030 (w), 946 (w), 875 (w), 831 (w), 801 (s),
(w), 1400 (s), 1352 (s), 1334 (w), 1314 (s), 1271 (w), 1257 (w), 1209
(s), 1157 (w), 1125 (s), 1057 (s), 1035 (w), 985 (w), 942 (w), 899 (w),
À 1
20 (w), 630 (w), 610 (w), 529 (w), 437 (w) cm ; MS (APCI): m/z=
+
89.66 [M+H] , 456.33, 432.32; HRMS (ESI): m/z calcd for
8
58 (w), 836 (w), 809 (s), 763 (w), 742 (s), 712 (w), 691 (s), 651 (w),
+
+
+
À 1
62 84 2 2
H N O +H : 889.6606 [M+H] , found: 889.6609 [M+H] .
584 (w), 506 (w), 496 (w), 425 (w) cm ; MS (ESI): m/z=733.01 [M+
+
Na] , 503.35, 459.32, 415.30, 381.29, 353.26; HRMS (ESI): m/z calcd
for C H Br N O +Na : 731.02 [M+Na] , found: 731.01 [M+Na] .
(
6aSR,12aSR)-5,11-Didodecyl-2,8-bis(4-dodecyloxyphenyl)-
+
+
+
36
26
2
2
4
5,6,6a,11,12,12a-hexahydropentaleno[2,1-b:5,4-b’]diindole (Ph-
6
k): According to GP2, from 11 (50.0 mg, 62.1 mmol), KOH (9.00 mg,
(
6aSR,12aSR)-2,8-Dibromo-5,11-ditosyl-5,6,6a,11,12,12a-hexahy-
155 mmol), 1-bromododecane (0.39 mL, 39.0 mg, 155 mmol), recrys-
dropentaleno[2,1-b:5,4-b’]diindole (12e): To solution of
a
9
tallization from EtOAc; yield: 27.0 mg, 23.6 mmol, 38%, colorless
(
(
180 mg, 407 μmol) in abs. CH Cl2 (20 mL) with powdered NaOH
2
1
solid, m.p. 129°C; H NMR (400 MHz, CDCl ): δ=0.80–0.92 (m, 12H;
3
81.0 mg, 2.04 mmol) and Bu NBr (14.0 mg, 40.7 μmol) p-toluenesul-
4
CH ), 1.14–1.42 (m, 68H; CH ), 1.42–1.61 (m, 4H; CH ), 1.61–1.76 (m,
3
2
2
fonic acid chloride (163 mg, 855 μmol) was added and the reaction
mixture was stirred at room temperature for 16 h. The reaction
mixture was washed with H O (15 mL), dried (MgSO ), and the
4
3
6
H; CH ), 1.76–1.87 (m, 4H; CH ), 3.07–3.19 (m, 2H; 6-H , 12-H ),
2
2
a
a
.26–3.39 (m, 2H; 6-H , 12-H ), 3.81–3.96 (m, 4H; NCH ), 4.01 (t, J=
.6 Hz, 4H; OCH ), 4.55–4.68 (m, 2H; 6a-H, 12a-H), 6.98 (d, J=8.4 Hz,
b
b
2
2
4
2
solvent was removed under vacuum. The crude product was
4H; 3’-H), 7.25–7.27 (m, 2H; 4-H, 10-H), 7.30 (dd, J=8.5, 1.6 Hz, 2H;
3-H, 9-H), 7.58 (d, J=8.4 Hz, 4H; 2’-H), 7.69 ppm (d, J=1.6 Hz, 2H; 1-
dissolved in CH Cl (5 mL), precipitated with Et O and filtered off to
2
2
2
give 12e (243 mg, 324 mmol, 80%) as a colorless solid. M.p. 277°C;
1
3
1
H, 7-H); C NMR (101 MHz, CDCl
3
): δ=14.1 (CH
6.1, 27.1, 29.3, 29.3, 29.4, 29.4, 29.5, 29.5, 29.6, 29.6, 29.6, 29.6, 29.7,
9.7, 30.3, 31.0 (CH ), 31.9 (C-6, C-12), 31.9 (CH ), 44.9 (NCH ), 47.5
3 3
), 22.7 (CH ), 22.7,
H NMR (400 MHz, [D ]THF): δ=2.20 (s, 6H; 5’-H), 3.28–3.38 (m, 2H;
8
2
2
6-H , 12-H ), 3.45-3.56 (m, 2H; 6-H , 12-H ), 4.31–4.41 (m, 2H; 6a-H,
a
a
b
b
2
2
2
1
9
7
2a-H), 6.99 (d, J=8.4 Hz, 4H; 3’-H), 7.37 (dd, J=8.8, 2.0 Hz, 2H; 3-H,
(
C-6a, C-12a), 68.1 (OCH ), 109.9 (C-4, C-10), 114.7 (C-3’), 116.2 (C-1,
2
-H), 7.54 (d, J=8.4 Hz, 4H; 2’-H), 7.73 (d, J=2.0 Hz, 2H; 1-H, 7-H),
13
C-7), 119.3 (C-6b, C-12b), 120.0 (C-3, C-9), 124.3 (C-6c, C-12c), 128.2
(C-2’), 132.1 (C-2, C-8), 135.4 (C-1’), 140.3 (C-4a, C-10a), 145.2 (C-5a,
C-11a), 157.9 ppm (C-4’); FT-IR (ATR): ~n =2955 (w), 2918 (s), 2850 (s),
.92 ppm (d, J=8.8 Hz, 2H; 4-H, 10-H); C NMR (101 MHz, [D ]THF):
8
δ=21.4 (C-5’), 33.4 (C-6, C-12), 47.2 (C-6a, C-12a), 116.9 (C-4, C-10),
17.7 (C-2, C-8), 122.4 (C-1, C-7), 126.9 (C-3, C-9), 127.3 (C-2’), 127.7
1
1
1
7
715 (w), 1608 (w), 1576 (w), 1514 (w), 1461 (s), 1366 (w), 1242 (s),
(C-6b, C-12b), 129.1 (C-6c, C-12c), 130.6 (C-3’), 136.3 (C-1’), 140.1 (C-
4a, C-10a), 144.6 (C-5a, C-11a), 146.0 ppm (C-4’); FT-IR (ATR): ~n =
181 (w), 1140 (w), 1113 (w), 1029 (w), 870 (w), 829 (w), 801 (w),
À 1
72 (w), 721 (w), 640 (w), 610 (w), 575 (w), 531 (w), 435 (w) cm ;
2
1
1
1
6
921 (w), 2852 (w), 1721 (w), 1596 (w), 1560 (w), 1494 (w), 1454 (w),
431 (w), 1389 (w), 1367 (w), 1329 (w), 1305 (w), 1268 (w), 1251 (w),
218 (w), 1187 (w), 1170 (s), 1127 (w), 1089 (w), 1056 (w), 1023 (w),
004 (w), 939 (w), 906 (w), 862 (w), 829 (w), 807 (s), 738 (w), 702 (w),
+
MS (APCI): m/z=1141.93 [M+H] , 1073.63, 973.75, 922.01, 663.45,
+
6
22.03, 551.50, 443.23; HRMS (APCI): m/z calcd for C H N O +H :
80 120 2 2
+ +
1141.9423 [M+H] , found: 1141.9374 [M+H] .
À 1
82 (w), 664 (s), 581 (s), 564 (w), 539 (s), 494 (w), 422 (w) cm ; MS
General Procedure for the Suzuki-Coupling (GP3): The appropriate
diindole 9, 12a–e (226 mmol) was dried under vacuum with the
respective boronic acid 10a–e (905 mmol), K CO (2.26 mmol) and
+
+
(APCI): m/z=750.98 [M+H] , 595.96 [MÀ 2Ts] , 363.97; HRMS
2
3
Eur. J. Org. Chem. 2021, 1452–1465
www.eurjoc.org
1460
© 2021 The Authors. European Journal of Organic Chemistry published
by Wiley-VCH GmbH

Full Papers
doi.org/10.1002/ejoc.202001656
1
Pd(PPh ) (45.2 mmol) prior to dissolving in abs. THF/abs. toluene
less solid; H NMR (500 MHz, CDCl ): δ=0.89 (t, J=6.9 Hz, 6H; CH ),
3 3
3
4
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
(
22 mL, 1:1, v/v) and degassed H O (10 mL) under nitrogen
1.23–1.39 (m, 24H; CH ), 1.42 (t, J=7.1 Hz, 6H; COOCH CH ), 1.45–
1.53 (m, 4H; CH ), 1.77–1.87 (m, 4H; CH ), 3.34–3.44 (m, 2H; 6-H , 12-
2 2 a
2
2
2
3
atmosphere. The reaction mixture was stirred at 80 C for 16 h. After
cooling to room temperature, the reaction mixture was diluted with
H
°
H ), 3.50–3.60 (m, 2H; 6-H , 12-H ), 4.01 (t, J=6.6 Hz, 4H; OCH ),
a
b
b
2
O and EtOAc and purified by method A or B. Method A: the
4.34–4.43 (m, 4H; COOCH ), 4.45–4.50 (m, 2H; 6a-H, 12a-H), 7.00 (d,
2
2
organic layer was dried (MgSO ) and the solvent was evaporated.
J=8.7 Hz, 4H; 3’-H), 7.44 (dd, J=8.6, 1.9 Hz, 2H; 3-H, 9-H), 7.58 (d,
J=8.7 Hz, 4H; 2’-H), 7.64 (d, J=1.9 Hz, 2H; 1-H, 7-H), 8.15 ppm (d,
4
The resulting solid was purified by column chromatography on
silica as indicated for each compound. Method B: the precipitated
solid was filtered off, washed with EtOAc, and dried.
1
3
J=8.6 Hz, 2H; 4-H, 10-H); C NMR (126 MHz, CDCl ): δ=14.1 (CH ),
3
3
14.5 (COOCH CH ), 22.7, 26.1, 29.3, 29.4, 29.6, 29.6, 31.9 (CH ), 33.8
2
3
2
(C-6, C-12), 46.0 (C-6a, C-12a), 62.9 (COOCH ), 68.1 (OCH ), 114.8 (C-
2
2
2
,8-Bis(4-(dodecyloxy)phenyl)-5,6,6a,11,12,12a-hexahydropenta-
leno[2,1-b:5,4-b’]diindole (11): According to GP3, from 9 (100 mg,
26 mmol), 10c (277 mg, 905 mmol), K CO (313 mg, 2.26 mmol),
3’), 116.1 (C-4, C-10), 116.3 (C-1, C-7), 122.4 (C-3, C-9), 126.6 (C-6b,
C-12b), 126.8 (C-6c, C-12c), 128.3 (C-2’), 134.1 (C-1’), 136.0 (C-2, C-8),
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
2
2
3
1
39.4 (C-4a, C-10a), 142.3 (C-5a, C-11a), 151.1 (NCOO), 158.5 ppm
Pd(PPh ) (52.0 mg, 45.2 mmol); purification method A: chromatog-
raphy with hexanes/EtOAc (25:1); yield: 117 mg, 145 mmol, 64%,
colorless solid; H NMR (500 MHz, [D
6
3
4
(
C-4’); FT-IR (ATR): ~n =3066 (w), 3036 (w), 2920 (w), 2851 (w), 1727
(s), 1607 (w), 1580 (w), 1517 (w), 1459 (s), 1399 (s), 1377 (s), 1354
(w), 1333 (s), 1304 (w), 1293 (w), 1263 (s), 1252 (s), 1216 (s), 1189 (s),
1
]DMSO): δ=0.88 (t, J=7.1 Hz,
6
H; CH ), 1.22–1.40 (m, 32H; CH ), 1.44–1.52 (m, 4H; CH ), 1.77–1.85
3
2
2
1142 (w), 1118 (s), 1048 (w), 1028 (w), 987 (w), 946 (w), 910 (w), 872
(
m, 4H; CH ), 3.07–3.14 (m, 2H; 6-H , 12-H ), 3.25–3.34 (m, 2H; 6-H ,
2
a
a
b
(w), 836 (w), 815 (s), 764 (w), 750 (w), 732 (w), 692 (w), 608 (w), 572
1
6
7
2-H ), 3.99 (t, J=6.5 Hz, 4H; OCH ), 4.52–4.58 (m, 2H; 6a-H, 12a-H),
À 1
+
b
2
(
(
w), 531 (w), 434 (w) cm ; MS (EI): m/z (%)=892.5 (100) [M] , 848.5
3), 820.5 (13), 446.2 (3), 306.1 (4); HRMS (EI): m/z calcd for
.98 (d, J=8.6 Hz, 4H; 3’-H), 7.21–7.29 (m, 4H; 1-H, 3-H, 7-H, 9-H),
.56 (d, J=8.6 Hz, 4H; 2’-H), 7.62 (br s, 2H; NH), 7.66–7.69 ppm (m,
+
+
+
C H N O : 892.5390 [M] , found: 892.5395 [M] ; elemental
13
58 72
2
6
2H; 4-H, 10-H); C NMR (125 MHz, [D
]DMSO): δ=14.1 (CH ), 22.7,
6
3
analysis calcd (%) for C H N O : C 77.99, H 8.12, N 3.14; found: C
5
8
72
2
6
2
(
6.1, 29.4, 29.4, 29.6, 29.6, 29.7, 29.7 (CH ), 31.3 (C-6, C-12), 31.9
2
77.84, H 7.93, N 3.02.
CH ), 47.6 (C-6a, C-12a), 68.1 (OCH ), 111.6 (C-1, C-7), 114.7 (C-3’),
2
2
1
1
1
16.1 (C-4, C-10), 120.1 (C-3, C-9), 122.0 (C-2, C-8), 124.6 (C-6b, C-
2b), 128.2 (C-2’), 132.8 (C-6c, C-12c), 135.2 (C-1’), 140.4 (C-4a, C-
0a), 142.7 (C-5a, C-11a), 158.0 ppm (C-4’); FT-IR (ATR): ~n =3397 (w),
Diethyl (6aSR,12aSR)-2,8-bis(4-(dodecyloxy)phenyl)-6,6a,12,12a-
tetrahydropentaleno-[2,1-b:5,4-b’]diindole-5,11-dicarboxylate
(Ph-6c): According to GP3, from 12a (100 mg, 171 mmol), 10c
(209 mg, 682 mmol), K CO (236 mg, 1.71 mmol), Pd(PPh ) (20.0 mg,
3033 (w), 2920 (s), 2851 (s), 1738 (w), 1607 (w), 1577 (w), 1513 (s),
1456 (s), 1390 (w), 1353 (w), 1269 (w), 1237 (s), 1077 (w), 1135 (w),
2
3
3 4
17.1 mmol), purification method A: chromatography with hexanes/
EtOAc (50:1!CH Cl ); yield: 62.0 mg, 65.3 mmol, 38%, colorless
1
(
[
8
101 (w), 1031 (w), 985 (w), 928 (w), 875 (w), 833 (s), 801 (s), 722
2
2
À 1
1
m), 680 (w), 616 (w), 597 (w), 534 (w) cm ; MS (ESI): m/z=804.6
solid; H NMR (500 MHz, CDCl ): δ=0.89 (t, J=6.9 Hz, 6H; CH ), 1.22-
3 3
+
+
M] , 554.4, 278.2, 110.0; HRMS (ESI): m/z calcd for C H N O
:
1.40 (m, 32H; CH ), 1.42 (t, J=7.1 Hz, 6H; COOCH CH ), 1.45–1.53 (m,
56
72
2
2
2
2
3
+
+
À 1
04.5594 [M] , found: 804.5601 [M] . DSC: Cr 212°C (7.5 kJmol )
4H; CH ), 1.77–1.86 (m, 4H; CH ), 3.35–3.42 (m, 2H; 6-H , 12-H ),
2 2 a a
À 1
SmA 242°C (5.4 kJmol ) I (2.heating).
3.50–3.59 (m, 2H; 6-H , 12-H ), 4.01 (t, J=6.6 Hz, 4H; OCH ), 4.34-
b
b
2
4.49 (m, 6H; COOCH 6a-H, 12a-H), 6.99 (d, J=8.7 Hz, 4H; 3’-H), 7.44
2
,
Diethyl (6aSR,12aSR)-2,8-bis(4-(octyloxy)phenyl)-6,6a,12,12a-tet-
(dd, J=8.6, 1.9 Hz, 2H; 3-H, 9-H), 7.58 (d, J=8.7 Hz, 4H; 2’-H), 7.64
(d, J=1.9 Hz, 2H; 1-H, 7-H), 8.14 ppm (d, J=8.6 Hz, 2H; 4-H, 10-H);
13
rahydropentaleno[2,1-b:5,4-b’]diindole-5,11-dicarboxylate
(Ph-
6
a): According to GP3, from 12a (305 mg, 520 mmol), 10a (390 mg,
C NMR (126 MHz, CDCl ): δ=14.1 (CH ), 14.5 (CO CH CH ), 22.7,
3
3
2
2
3
1.56 mmol), K CO3 (216 mg, 1.56 mmol), Pd(PPh3)4 (60.0 mg, 52.0
2
2
1
1
6.1, 29.4, 29.4, 29.4, 29.6, 29.6, 29.7, 29.7, 31.9 (CH ), 33.8 (C-6, C-
2
mmol), purification method B; yield: 198 mg, 237 mmol, 45%, color-
less solid; H NMR (500 MHz, CDCl ): δ=0.90 (t, J=6.8 Hz, 6H; CH ),
1
2), 46.0 (C-6a, C-12a), 62.9 (COOCH ), 68.1 (OCH ), 114.8 (C-3’),
1
2
2
3
3
16.1 (C-4, C-10), 116.3 (C-1, C-7), 122.4 (C-3, C-9), 126.6 (C-6b, C-
.23–1.39 (m, 16H; CH ), 1.41 (t, J=7.1 Hz, 6H; COOCH CH ), 1.45–
2
2
3
12b), 126.8 (C-6c, C-12c), 128.3 (C-2’), 134.1 (C-1’), 136.0 (C-2, C-8),
39.4 (C-4a, C-10a), 142.3 (C-5a, C-11a), 151.1 (NCOO), 158.5 ppm
1
.53 (m, 4H; CH ), 1.77–1.86 (m, 4H; CH ), 3.35–3.41 (m, 2H; 6-H , 12-
2
2
a
1
H ), 3.50–3.58 (m, 2H; 6-H , 12-H ), 4.01 (t, J=6.6 Hz, 4H; OCH ),
a
b
b
2
(
(
(
(
C-4’); FT-IR (ATR): ~n =3394 (w), 2913 (s), 2850 (w), 1727 (s), 1607
w), 1580 (w), 1518 (w), 1459 (s), 1399 (w), 1376 (s), 1353 (w), 1332
s), 1303 (w), 1293 (w), 1262 (s), 1252 (s), 1235 (w), 1215 (w), 1187
s), 1143 (w), 1117 (s), 1047 (s), 1029 (w), 910 (w), 871 (w), 836 (w),
4
.34-4.48 (m, 6H; COOCH , 6a-H, 12a-H), 6.99 (d, J=8.8 Hz, 4H; 3’-H),
2
7.43 (dd, J=8.6, 1.9 Hz, 2H; 3-H, 9-H), 7.58 (d, J=8.8 Hz, 4H; 2’-H),
7.64 (d, J=1.9 Hz, 2H; 1-H, 7-H), 8.14 ppm (d, J=8.6 Hz, 2H; 4-H, 10-
H); C NMR (126 MHz, CDCl ): δ=14.1 (CH ), 14.5 (CO CH CH ), 22.7,
13
3
3
2
2
3
835 (w), 813 (s), 763 (w), 749 (w), 722 (w), 691 (w), 662 (w), 621 (w),
2
6
1
1
6.1, 29.3, 29.3, 29.4, 31.8 (CH ), 33.8 (C-6,C-12), 46.0 (C-6a, C-12a),
À 1
2
608 (w), 571 (w), 531 (w), 434 (w) cm ; MS (APCI): m/z=949.61 [M
2.9 (COOCH ), 68.1 (OCH ), 114.8 (C-3’), 116.1 (C-4, C-10), 116.3 (C-
+
2
2
+
H] , 663.45, 607.39, 462.30, 394.34, 333.16; HRMS (APCI): m/z
, C-7), 122.4 (C-3, C-9), 126.6 (C-6b, C-12b), 126.8 (C-6c, C-12c),
28.3 (C-2’), 134.1 (C-1’), 136.0 (C-2, C-8), 139.4 (C-4a, C-10a), 142.3
+
+
calcd for C H N O +H : 949.6089 [M+H] , found: 949.6085 [M+
6
2
80
2
6
+
H] ; elemental analysis calcd (%) for C H N O : C 78.44, H 8.50, N
6
2
80
2
6
(C-5a, C-11a), 151.1 (NCOO), 158.5 (C-4’); FT-IR (ATR): ~n =3036 (w),
2.95; found: C 78.55, H 8.62, N 2.73.
2
1
1
9
6
923 (w), 2854 (w), 1729 (s), 1607 (w), 1580 (w), 1517 (w), 1459 (s),
400 (w), 1377 (s), 1352 (w), 1332 (s), 1303 (w), 1293 (w), 1262 (s),
251 (s), 1215 (s), 1184 (w), 1141 (w), 1118 (s), 1046 (w), 1030 (w),
71 (w), 909 (w), 873 (w), 836 (w), 814 (s), 763 (w), 725 (w), 691 (w),
Diethyl
(6aSR,12aSR)-2,8-bis(4-(tetradecyloxy)phenyl)-
6,6a,12,12a-tetrahydropentaleno-[2,1-b:5,4-b’]diindole-5,11-dicar-
boxylate (Ph-6d): According to GP3, from 12a (250 mg, 426 mmol),
10d (428 mg, 1.28 mmol), K CO (177 mg, 1.28 mmol), Pd(PPh3)4
À 1
08 (w), 572 (w), 531 (w), 434 (w) cm ; MS (EI): m/z (%)= 836.4
2
3
+
(100) [M] , 808.4 (3), 764.4 (8), 466.2 (3), 418.2 (3), 306.1 (3); HRMS
(49.0 mg, 42.6 mmol), purification method B; yield: 133 mg, 132
1
+
+
(EI): m/z calcd for C54
elemental analysis calcd (%) for C H N O : C 77.48, H 7.71, N 3.35;
found: C 77.26, H 7.52, N 3.24.
H
64
N
O
2
: 836.4764 [M] , found: 836.4743 [M] ;
mmol, 31%, colorless solid; H NMR (500 MHz, CDCl ): δ=0.88 (t, J=
3
6
6.8 Hz, 6H; CH ), 1.19–1.40 (m, 40H; CH ), 1.42 (t, J=7.1 Hz, 6H;
54 64
2
6
3
2
COOCH CH ), 1.45–1.52 (m, 4H; CH ), 1.79–1.85 (m, 4H; CH ), 3.33-
2 3 2 2
3
6
.45 (m, 2H; 6-H , 12-H ), 3.50–3.60 (m, 2H; 6-H , 12-H ), 4.02 (t, J=
a
a
b
b
Diethyl (6aSR,12aSR)-2,8-bis(4-(decyloxy)phenyl)-6,6a,12,12a-tet-
.5 Hz, 4H; OCH ), 4.35–4.46 (m, 4H; COOCH ), 4.45–4.51 (m, 2H; 6a-
2
2
rahydropentaleno[2,1-b:5,4-b’]diindole-5,11-dicarboxylate (Ph-
b): According to GP3, from 12a (400 mg, 682 mmol), 10b (569 mg,
.05 mmol), K CO3 (283 mg, 2.05 mmol), Pd(PPh3)4 (79.0 mg, 68.2
H, 12a-H), 7.00 (d, J=8.3 Hz, 4H; 3’-H), 7.44 (dd, J=8.6, 1.6 Hz, 2H;
3-H, 9-H), 7.59 (d, J=8.3 Hz, 4H; 2’-H), 7.65 (d, J=1.6 Hz, 2H; 1-H, 7-
6
2
13
2
H), 8.15 ppm (d, J=8.6 Hz, 2H; 4-H, 10-H); C NMR (176 MHz,
mmol), purification method B; yield: 244 mg, 273 mmol, 40%, color-
Eur. J. Org. Chem. 2021, 1452–1465
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© 2021 The Authors. European Journal of Organic Chemistry published
by Wiley-VCH GmbH

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CDCl ): δ=14.1 (CH ), 14.5 (COOCH CH ), 22.7, 26.1, 29.3, 29.4, 29.4,
(w), 749 (w), 735 (w), 691 (w), 646 (w), 609 (w), 577 (w), 531 (w), 434
+ +
3
3
2
3
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
À 1
2
9.6, 29.6, 29.7, 29.7, 29.7, 29.7, 31.9 (CH ), 33.8 (C-6, C-12), 46.0 (C-
(w) cm ; MS (APCI): m/z=921.57 [M+H] , 889.65 [MÀ OCH +H] ,
2
3
+
+
6a, C-12a), 62.9 (COOCH ), 68.1 (OCH ), 114.8 (C-3’), 116.1 (C-4, C-
863.56 [M–COOCH +H] , 663.45 [M–CO CH +H] , 576.43, 506.47,
3 2 3
+
448.28, 394.34, 333.17; HRMS (APCI): m/z calcd for C H N O +H :
60 76 2 6
+ +
2
2
10), 116.3 (C-1, C-7), 122.4 (C-3, C-9), 126.6 (C-6b, C-12b), 126.8 (C-
6c, C-12c), 128.3 (C-2’), 134.1 (C-1’), 136.0 (C-2, C-8), 139.4 (C-4a, C-
921.5776 [M+H] , found: 921.5698 [M+H] .
1
0a), 142.3 (C-5a, C-11a), 151.1 (NCOO), 158.5 ppm (C-4’); FT-IR
Di-tert-butyl (6aSR,12aSR)-2,8-bis(4-dodecyloxypheny-
(
ATR): ~n =2918 (s), 2850 (s), 1727 (s), 1607 (w), 1580 (w), 1518 (w),
l)-6,6a,12,12a-tetrahydropentale-no-[2,1-b:5,4-b’]diindole-5,11-di-
carboxylate (Ph-6g): According to GP3, from 12c (100 mg, 156
mmol), 10c (354 mg, 623 mmol), K CO (215 mg, 1.56 mmol), Pd-
1
1
459 (s), 1400 (s), 1377 (s), 1353 (w), 1333 (s), 1304 (w), 1293 (w),
262 (s), 1252 (s), 1216 (s), 1187 (s), 1143 (w), 1118 (s), 1048 (w),
2
3
1025 (w), 978 (w), 909 (w), 872 (w), 836 (w), 814 (s), 764 (w), 750 (w),
733 (w), 722 (w), 692 (w), 663 (w), 609 (w), 572 (w), 532 (w), 499 (w),
(
PPh ) (11.0 mg, 9.30 mmol); purification method A: chromatogra-
3 4
À 1
+
phy with hexanes/EtOAc (50:1!10:1); yield: 71.0 mg, 70.6 mmol,
4
3
35 (w) cm ; MS (ESI): m/z=1027.64 [M+Na] , 685.43, 447.34,
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
1
+
45%, colorless solid, m.p.146°C; H NMR (700 MHz, CDCl
3
): δ=0.89
93.29; HRMS (ESI): m/z calcd for C H N O +Na : 1027.6535 [M+
Na] , found: 1027.6505 [M+Na] ; elemental analysis calcd (%) for
66
88
2
6
+
+
(t, J=7.1 Hz, 6H; CH ), 1.23–1.41 (m, 32H; CH ), 1.45–1.51 (m, 4H;
3 2
CH ), 1.62 (s, 18H; BOC-CH ), 1.79–1.86 (m, 4H; CH ), 3.36–3.44 (m,
2
3
2
C H N O : C 78.84, H 8.82, N 2.79; found: C 78.81, H 8.64, N 2.75.
6
6
88
2
6
2H; 6-H
, 12-H
), 3.52–3.60 (m, 2H; 6-H , 12-H ), 4.02 (t, J=6.5 Hz,
a
a
b b
Diethyl
,6a,12,12a-tetrahydropentaleno[2,1-b:5,4-b’]diindole-5,11-dicar-
boxylate (Ph-6e): According to GP3, from 12a (300 mg, 512 mmol),
0e (556 mg, 1.54 mmol), K CO3 (212 mg, 1.54 mmol), Pd(PPh3)4
(6aSR,12aSR)-2,8-bis(4-(hexadecyloxy)phenyl)-
4H; OCH ), 4.44-4.50 (m, 2H; 6a-H, 12a-H), 6.99 (d, J=8.4 Hz, 4H; 3’-
2
6
H), 7.43 (dd, J=8.5, 1.8 Hz, 2H; 3-H, 9-H), 7.58 (d, J=8.4 Hz, 4H; 2’-
H), 7.64 (d, J=1.8 Hz, 2H; 1-H, 7-H), 8.08–8.16 ppm (m, 2H; 4-H, 10-
13
1
H); C NMR (176 MHz, CDCl ): δ=14.1 (CH ), 22.7, 26.1 (CH ), 28.2
2
3
3
2
(
59.0 mg, 51.2 mmol), purification method B; yield: 122 mg, 114
mmol, 22%, colorless solid; H NMR (500 MHz, CDCl
(BOC-CH ), 29.3, 29.4, 29.4, 29.6, 29.6, 29.7, 29.7, 31.9 (CH ), 34.0 (C-
3
2
1
): δ=0.88 (t, J=
6, C-12), 45.9 (C-6a, C-12a), 68.1 (OCH
), 83.4 (C(CH
)
3
), 114.8 (C-3’),
3
3
2
6
.8 Hz, 6H; CH ), 1.20–1.38 (m, 48H; CH ), 1.41 (t, J=7.1 Hz, 6H;
116.2 (C-1, C-7), 116.2 (C-4, C-10), 122.2 (C-3, C-9), 126.4 (C-6b, C-
12b), 126.5 (C-6c, C-12c), 128.2 (C-2’), 134.1 (C-1’), 135.8 (C-2, C-8),
139.4 (C-4a, C-10a), 142.7 (C-5a, C-11a), 149.8 (NCOO), 158.4 ppm
(C-4’); FT-IR (ATR): ~n =2922 (w), 2852 (w), 1725 (s), 1606 (w), 1579
(w), 1516 (w), 1459 (s), 1420 (w), 1369 (s), 1331 (w), 1303 (w), 1294
(w), 1263 (w), 1250 (s), 1219 (w), 1170 (w), 1143 (w), 1119 (s), 1026
(w), 966 (w), 873 (w), 837 (w), 815 (w), 767 (w), 725 (w), 687 (w), 608
3
2
COOCH CH ), 1.44–1.53 (m, 4H; CH ), 1.74–1.87 (m, 4H; CH ), 3.30–
2
3
2
2
3
6
.44 (m, 2H; 6-H , 12-H ), 3.47–3.58 (m, 2H; 6-H , 12-H ), 4.00 (t, J=
a
a
b
b
.6 Hz, 4H; OCH ), 4.33–4.44 (m, 4H; COOCH ), 4.44–4.47 (m, 2H; 6a-
2
2
H, 12a-H), 6.99 (d, J=8.7 Hz, 4H; 3’-H), 7.43 (dd, J=8.6, 1.8 Hz, 2H;
3-H, 9-H), 7.58 (d, J=8.7 Hz, 4H; 2’-H), 7.64 (d, J=1.8 Hz, 2H; 1-H, 7-
13
H), 8.14 ppm (d, J=8.6 Hz, 2H; 4-H, 10-H); C NMR (126 MHz,
CDCl ): δ=14.2 (CH ), 14.5 (COOCH CH ), 22.7, 26.1, 29.4, 29.4, 29.5,
À 1
(w), 572 (w), 532 (w), 494 (w), 471 (w), 434 (w) cm ; MS (ESI): m/z=
3
3
2
3
+
2
1
1
1
9.7, 29.7, 29.7, 29.7, 29.8, 32.0 (CH ), 33.9 (C-6, C-12), 46.0 (C-6a, C-
1027.61 [M+Na] , 685.42, 663.44, 625.43, 597.40, 447.34, 393.29,
2
+
2a), 62.9 (COOCH ), 68.2 (OCH ), 114.8 (C-3’), 116.1 (C-4, C-10),
333.16; HRMS (ESI): m/z calcd for C H N O +Na : 1027.6535 [M+
2
2
66 88
2
6
+
+
16.3 (C-1, C-7), 122.4 (C-3, C-9), 126.6 (C-6b, C-12b), 126.9 (C-6c, C-
2c), 128.3 (C-2’), 134.1 (C-1’), 136.1 (C-2, C-8), 139.4 (C-4a, C-10a),
Na] , found: 1027.6483 [M+Na] ; elemental analysis calcd (%) for
C H N O : C 78.84, H 8.82, N 2.79; found: C 77.97, H 8.59, N 2.67.
6
6
88
2
6
142.4 (C-5a, C-11a), 151.1 (NCOO), 158.5 ppm (C-4’); FT-IR (ATR): ~n =
Dibenzyl (6aSR,12aSR)-2,8-bis(4-dodecyloxyphenyl)-6,6a,12,12a-
tetrahydropentaleno-[2,1-b:5,4-b’]diindole-5,11-dicarboxylate
2917 (s), 2849 (s), 1727 (s), 1607 (w), 1518 (w), 1459 (s), 1400 (s),
1
1
8
5
377 (s), 1353 (w), 1333 (s), 1304 (w), 1293 (w), 1262 (s), 1252 (s),
216 (s), 1188 (s), 1143 (w), 1118 (s), 1047 (w), 1026 (w), 909 (w),
72 (w), 836 (w), 814 (s), 764 (w), 733 (w), 721 (w), 692 (w), 609 (w),
(
Ph-6h): According to GP3, from 12d (100 mg, 156 mmol), 10c
(172 mg, 563 mmol) K CO (195 mg, 1.41 mmol), Pd(PPh ) (16.0 mg,
2
3
3 4
À 1
8.40 mmol), purification method A: chromatography with hexanes/
72 (w), 531 (w), 505 (w), 434 (w) cm ; MS (EI): m/z=1060.7 (100)
+
EtOAc (50:1!5:1); yield: 15 mg, 13.9 mmol, 10%, colorless solid,
[M] , 988.7 (21), 820 (4), 748.5 (4), 518.4 (5), 466.2 (4), 306.1 (11),
1
+
m.p. >350°C; H NMR (500 MHz, CDCl
3
): δ=0.88 (t, J=6.8 Hz, 6H;
91.1 (5), 71.1 (5); HRMS (EI): m/z calcd for C70
H
N
O
: 1060.7268
M] , found: 1060.7272 [M] ; elemental analysis calcd (%) for
C H N O : C 79.20, H 9.12, N 2.64; found: C 79.08, H 8.83, N 2.45.
96
2
6
+
+
CH ), 1.20–1.44 (m, 32H; CH ), 1.45–1.55 (m, 4H; CH ), 1.78–1.89 (m,
3 2 2
[
4
H; CH ), 3.27–3.39 (m, 2H; 6-H , 12-H ), 3.41–3.52 (m, 2H; 6-H , 12-
2
a
a
b
7
0
96
2
6
H ), 4.04 (t, J=6.6 Hz, 4H; OCH ), 4.34–4.49 (m, 2H; 6a-H, 12a-H),
b
2
Dimethyl (6aSR,12aSR)-2,8-bis(4-dodecyloxyphenyl)-6,6a,12,12a-
tetrahydropentaleno-[2,1-b:5,4-b’]diindole-5,11-dicarboxylate
5.36 (s, 4H; COOCH ), 7.01 (d, J=8.7 Hz, 4H; 3’-H), 7.21–7.31 (m, 6H;
2
4’’-H, 5’’-H), 7.36–7.46 (m, 6H; 3-H, 9-H, 3’’-H), 7.52–7.60 (m, 6H; 1-H,
1
3
(
(
(
Ph-6f): According to GP3, from 12b (150 mg, 269 mmol), 10c
329 mg, 1.07 mmol), K2CO3 (371 mg, 2.69 mmol), Pd(PPh3)4
31.0 mg, 26.9 mmol), purification method A: chromatography with
7-H, 2’-H), 8.11–8.20 ppm (m, 2H; 4-H, 10-H); C NMR (126 MHz,
CDCl ): δ=14.1 (CH ), 22.7, 26.1, 29.4, 29.5, 29.6, 29.6, 29.7, 29.7,
3
3
29.7, 31.9 (CH ), 33.8 (C-6, C-12), 46.0 (C-6a, C-12a), 68.2 (OCH ), 68.5
2
2
hexanes/EtOAc (50:1!5:1); yield: 80 mg, 86.8 mmol, 32%, colorless
(C-1’’), 114.8 (C-3’), 116.1 (C-4, C-10), 116.3 (C-1, C-7), 122.5 (C-3, C-
9), 126.6 (C-6c, C-12c), 127.0 (C-6b, C-12b), 128.3, 128.4, 128.6, 128.7
(C-2’, C-3’’, C-4’’, C-5’’), 134.1 (C-1’), 135.0 (C-2’’), 136.2 (C-2, C-8),
139.4 (C-4a, C-10a), 142.1 (C-5a, C-11a), 150.8 (NCOOCH2),
158.5 ppm (C-4’); FT-IR (ATR): ~n =3064 (w), 3035 (w), 2922 (s), 2852
(s), 1729 (s), 1608 (w), 1516 (w), 1461 (s), 1402 (s), 1359 (s), 1335 (w),
1304 (w), 1248 (s), 1214 (s), 1181 (w), 1124 (s), 1028 (s), 908 (w), 874
(w), 814 (s), 761 (w), 750 (w), 729 (w), 694 (w), 665 (w), 625 (w), 609
(w), 582 (w), 531 (w), 496 (w), 456 (w), 446 (w), 434 (w), 409 (w)
1
solid, m.p. 184 C; H NMR (700 MHz, CDCl ): δ=0.89 (t, J=7.0 Hz,
°
3
6H; CH ), 1.23–1.41 (m, 32H; CH ), 1.45–1.52 (m, 4H; CH ), 1.82 (d, J=
6
3
2
2
.7 Hz, 4H; CH ), 3.32–3.40 (m, 2H; 6-H , 12-H ), 3.47–3.57 (m, 2H; 6-
2
a
a
H , 12-H ), 3.95 (s, 6H; COOCH ), 4.01 (t, J=6.6 Hz, 4H; OCH ), 4.44–
b
b
3
2
4
8
1
.50 (m, 2H; 6a-H, 12a-H), 7.00 (d, J=8.7 Hz, 4H; 3’-H), 7.44 (dd, J=
.6, 1.8 Hz, 2H; 3-H, 9-H), 7.59 (d, J=8.7 Hz, 4H; 2’-H), 7.65 (d, J=
13
.8 Hz, 2H; 1-H, 7-H), 8.10–8.19 ppm (m, 2H; 4-H, 10-H); C NMR
(176 MHz, CDCl ): δ=14.1 (CH ), 22.7, 26.1, 29.3, 29.4, 29.4, 29.6,
3
3
À 1
+
29.7, 29.7, 30.3, 31.9 (CH
), 33.7 (C-6, C-12), 46.0 (C-6a, C-12a), 53.5
2
cm ; MS (APCI): m/z=1073.63 [M+H] , 1029.64, 922.01, 874.47,
813.42 [M-C H OC H +H], 769.43, 721.36, 663.45, 614.36, 570.37,
(
7
1
COOCH ), 68.1 (OCH ), 114.8 (C-3’), 116.1 (C-4, C-10), 116.3 (C-1, C-
), 122.4 (C-3, C-9), 126.9 (C-6c, C-12c), 128.3 (C-2’), 128.3 (C-6b, C-
2b), 134.0 (C-1’), 136.1 (C-2, C-8), 139.4 (C-4a, C-10a), 142.2 (C-5a,
3
2
6
4
12 25
524.31, 480.32, 429.09, 354.15, 310.16, 264.10; HRMS (APCI): m/z
+
+
calcd for C H N O +H : 1073.6402 [M+H] , found: 1073.6392 [M
7
2
84
2
6
+
C-11a), 151.6 (NCOO), 158.5 ppm (C-4’); FT-IR (ATR): ~n =3038 (w),
920 (s), 2851 (w), 1737 (w), 1603 (w), 1568 (w), 1516 (w), 1460 (s),
+H] .
2
(
5
6
6aSR,12aSR)-2,8-Bis(4-dodecyloxyphenyl)-5,11-ditosyl-
,6,6a,11,12,12a-hexahydropentaleno[2,1-b:5,4-b’]diindole (Ph-
i): According to GP3, from 12e (175 mg, 233 mmol), 10c (286 mg,
1442 (w), 1413 (w), 1366 (s), 1343 (s), 1305 (w), 1244 (s), 1217 (s),
1171 (s), 1122 (s), 1031 (w), 909 (w), 876 (w), 834 (w), 814 (w), 762
Eur. J. Org. Chem. 2021, 1452–1465
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© 2021 The Authors. European Journal of Organic Chemistry published
by Wiley-VCH GmbH

Full Papers
doi.org/10.1002/ejoc.202001656
9
33 mmol), K CO3 (322 mg, 2.33 mmol), Pd(PPh3)4 (27.0 mg, 23.3
29.5, 29.6, 29.7, 29.7, 29.7, 29.8, 29.8, 30.4, 31.9, 32.0 (CH ), 33.9 (C-6,
2
2
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
mmol), purification method A: chromatography with hexanes/EtOAc
C-12), 46.0 (C-6a, C-12a), 62.9 (COOCH ), 69.4 (m-OCH ), 73.6 (p-
2
2
(
50:1!CH Cl ); yield: 41 mg, 36.8 mmol, 16%, colorless solid, m.p.
OCH ), 106.5 (C-2’), 116.1 (C-4, C-10), 116.6 (C-1, C-7), 122.8 (C-3, C-
2
2
2
1
183°C; H NMR (400 MHz, CDCl ): δ=0.88 (t, J=6.7 Hz, 6H; CH ),
9), 126.5 (C-6b, C-12b), 126.8 (C-6c, C-12c), 136.7 (C-2, C-8), 137.2 (C-
1’), 137.8 (C-4’), 139.7 (C-4a, C-10a), 142.4 (C-5a, C-11a), 151.1
(NCOO), 153.4 ppm (C-3’); FT-IR (ATR): ~n =2921 (s), 2852 (w), 1736
(w), 1583 (w), 1566 (w), 1508 (w), 1458 (s), 1424 (w), 1377 (w), 1336
(w), 1258 (w), 1216 (w), 1116 (s), 1041 (w), 907 (s), 814 (w), 764 (w),
3
3
1.19–1.42 (m, 32H; CH
), 1.42–1.53 (m, 4H; CH
2
), 1.81 (d, J=7.1 Hz,
2
4
H; CH ), 2.16 (s, 6H; 5’’-H), 3.31–3.48 (m, 2H; 6-H , 12-H ), 3.49–3.61
2
a
a
(m, 2H; 6-H , 12-H ), 4.01 (t, J=6.5 Hz, 4H; OCH ), 4.35–4.48 (m, 2H;
b
b
2
6
a-H, 12a-H), 6.79 (d, J=8.1 Hz, 4H; 3’’-H), 6.99 (d, J=8.7 Hz, 4H; 3’-
À 1
H), 7.42–7.49 (m, 6H; 2’’-H, 3-H, 9-H), 7.55 (d, J=8.7 Hz, 4H; 2’-H),
7.62 (d, J=1.7 Hz, 2H; 1-H, 7-H), 8.02 ppm (d, J=8.6 Hz, 2H; 4-H, 10-
731 (s), 641 (w), 584 (w), 496 (w) cm ; MS (ESI): m/z=1709 [M+
+
+
Na] ; HRMS (ESI): m/z calcd for C110H176N O +Na : 1708.3217 [M+
2
10
13
+
+
H); C NMR (101 MHz, CDCl
): δ=14.1 (CH
), 21.5 (C-5’’), 22.7, 26.1,
3
Na] , found: 1708.3174 [M+Na] .
3
2
4
9.3, 29.4, 29.4, 29.6, 29.6, 29.6, 29.7, 31.9 (CH ), 32.6 (C-6, C-12),
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
2
Diethyl (6aSR,12aSR)-2,8-bis(4’-(decyloxy)-[1,1’-biphenyl]-4-yl)-
6.4 (C-6a, C-12a), 68.1 (OCH ), 114.8 (C-4, C-10), 114.8 (C-3’), 116.7
2
6
,6a,12,12a-tetrahydropentaleno[2,1-b:5,4-b’]diindole-5,11-dicar-
(
C-1, C-7), 122.6 (C-3, C-9), 126.2 (C-2’’), 127.0 (C-2, C-8), 127.9 (C-6b,
C-12b), 128.3 (C-2’), 129.6 (C-3’’), 133.5 (C-1’), 135.3 (C-1’’), 136.9 (C-
c, C-12c), 139.4 (C-4a, C-10a), 142.5 (C-5a, C-11a), 144.5 (C-4’’),
boxylate (Biph-6a): According to GP3, from 12a (250 mg, 426
mmol),
[24a]
4’-(decyloxy)-4-biphenylboronic
acid
(553 mg,
6
1
.28 mmol), K CO (117 mg, 1.28 mmol), Pd(PPh3)4 (49.0 mg, 42.6
2
3
158.7 ppm (C-4’); FT-IR (ATR): ~n =2918 (w), 2851 (w), 1606 (w), 1515
(w), 1453 (w), 1363 (s), 1332 (w), 1300 (w), 1274 (w), 1239 (w), 1206
mmol), purification method B and subsequent recrystallization from
CH Cl ; yield: 101 mg, 96.6 mmol, 23%, colorless solid; H NMR
1
2
2
(
(
w), 1186 (w), 1167 (s), 1132 (w), 1117 (w), 1099 (w), 1087 (w), 1030
w), 1016 (w), 1003 (w), 973 (w), 944 (w), 907 (w), 835 (w), 812 (s),
(
700 MHz, CDCl ): δ=0.89 (t, J=7.0 Hz, 6H; CH ), 1.23–1.40 (m, 24H;
3
3
CH ), 1.43 (t, J=7.1 Hz, 6H; COOCH CH ), 1.45–1.51 (m, 4H; CH ),
2
2
3
2
7
52 (w), 721 (w), 701 (w), 669 (s), 637 (w), 623 (w), 607 (w), 581 (s),
À 1
1.78–1.85 (m, 4H; CH ), 3.36–3.44 (m, 2H; 6-H
2
, 12-H
a
a
), 3.53–3.61 (m,
5
42 (s), 488 (w), 431 (w), 420 (w) cm ; MS (MALDI-TOF): m/z calcd
+
+
+
2
H; 6-H , 12-H ), 4.00 (t, J=6.5 Hz, 4H; OCH ), 4.34–4.49 (m, 4H;
b
b
2
for C H N O S : 1112.5 [M] , found: 1111.2 [M] .
70
84
2
6 2
COOCH ), 4.47-4.54 (m, 2H; 6a-H, 12a-H), 6.99 (d, J=8.6 Hz, 4H; 7’-
2
Diethyl
,6a,12,12a-tetra-hydropentaleno[2,1-b:5,4-b’]diindole-5,11-dicar-
boxylate (Ph-6l): According to GP3, from 12a (75.0 mg, 128 mmol),
(6aSR,12aSR)-2,8-bis[3,4-bis(dodecyloxy)phenyl]-
H), 7.52 (dd, J=8.5, 1.9 Hz, 2H; 3-H, 9-H), 7.58 (d, J=8.6 Hz, 4H; 6’-
H), 7.65 (d, J=8.3 Hz, 4H; 3’-H), 7.72 (d, J=8.3 Hz, 4H; 2’-H), 7.74 (d,
6
13
J=1.9 Hz, 2H; 1-H, 7-H), 8.15–8.25 ppm (m, 2H; 4-H, 10-H); C NMR
[
17]
3,4-bis(dodecyloxy)phenylboronic acid (188 mg, 384 mmol), K CO
(53.0 mg, 384 mmol), Pd(PPh
(176 MHz, CDCl ): δ=14.2 (CH ), 14.5 (CO CH CH ), 22.7, 26.1, 29.3,
2
3
3
3
2
2
3
)
3
(15.0 mg, 12.8 mmol), purification
29.3, 29.4, 29.6, 29.6, 31.9 (CH ), 33.8 (C-6, C-12), 46.0 (C-6a, C-12a),
4
2
method A: chromatography with hexanes/EtOAc (50:1!10:1);
62.9 (COOCH ), 68.1 (OCH ), 114.8 (C-7’), 116.2 (C-4, C-10), 116.5 (C-
2 2
1
yield: 86.0 mg, 65.2 mmol, 51%, colorless solid, m.p. 168°C; H NMR
1, C-7), 122.5 (C-3, C-9), 126.6 (C-6b, C-12b), 126.8 (C-6c, C-12c),
127.0 (C-3), 127.6 (C-2’), 128.0 (C-6’), 133.0 (C-5’), 135.8 (C-2, C-8),
139.4 (C-4’), 139.8 (C-4a, C-10a), 139.9 (C-1’), 142.4 (C-5a, C-11a),
151.1 (NCOO), 158.7 ppm (C-8’); FT-IR (ATR): ~n =2920 (w), 2850 (w),
1728 (s), 1605 (w), 1501 (w), 1458 (s), 1405 (w), 1375 (s), 1352 (w),
1325 (s), 1242 (s), 1213 (s), 1176 (w), 1117 (s), 1046 (w), 815 (s), 766
(500 MHz, CDCl ): δ=0.84–0.92 (m, 12H; CH ), 1.21–1.40 (m, 64H;
3
3
CH ), 1.43 (t, J=7.2 Hz, 6H; COOCH CH ), 1.45–1.55 (m, 8H; CH ),
2
2
3
2
1
.80-1.91 (m, 8H; CH ), 3.35–3.43 (m, 2H; 6-H , 12-H ), 3.51–3.61 (m,
2
a
a
2H; 6-H , 12-H ), 4.06 (t, J=6.6 Hz, 4H; OCH ), 4.10 (t, J=6.6 Hz, 4H;
OCH
6
b
b
2
), 4.36–4.48 (m, 4H; COOCH
), 4.48–4.53 (m, 2H; 6a-H, 12a-H),
2
2
À 1
.98 (d, J=8.0 Hz, 2H; 5’-H), 7.16–7.22 (m, 4H; 2’-H, 6’-H), 7.44 (dd,
(w), 704 (w), 524 (w) cm ; MS (MALDI-TOF): m/z calcd for
+
J=8.6, 1.8 Hz, 2H; 3-H, 9-H), 7.64 (d, J=1.8 Hz, 2H; 1-H, 7-H),
C H N O : 1440.6, found: 1042.1; elemental analysis calcd (%) for
7
0
80
2
6
13
8
.16 ppm (d, J=8.6 Hz, 2H; 4-H, 10-H); C NMR (126 MHz, CDCl3):
C H N O : C 80.42, H 7.72, N 2.68; found: C 80.06, H 7.59, N 2.66.
70 80 2 6
À 1
δ=14.1 (CH ), 14.5 (COOCH CH ), 22.7, 26.1, 26.1, 29.4, 29.4, 29.5,
DSC: 203°C (30.2 kJmol ) N 338°C I (decomp., 1. heating).
3
2
3
2
9.5, 29.7, 29.7, 29.7, 31.9 (CH ), 33.9 (C-6a, C-12a), 46.0 (C-6, C-12),
2
Diethyl (6aSR,12aSR)-2,8-bis(4’-(dodecyloxy)-[1,1’-biphenyl]-4-yl)-
62.9 (COOCH
), 69.5 (OCH ), 69.6 (OCH ), 113.7 (C-6’), 114.3 (C-5’),
2 2
2
6
,6a,12,12a-tetrahydropentaleno[2,1-b:5,4-b’]diindole-5,11-dicar-
1
16.1 (C-4, C-10), 116.4 (C-1, C-7), 119.9 (C-2’), 122.6 (C-3, C-9), 126.5
boxylate (Biph-6b): According to GP3, from 12a (100 mg, 170
mmol), 4’-(dodecyloxy)-4-biphenylboronic acid
(
(
C-6b, C-12b), 126.8 (C-6c, C-12c), 134.9 (C-1’), 136.3 (C-2, C-8), 139.5
C-4a, C-10a), 142.4 (C-5a, C-11a), 148.7 (C-3’), 149.4 (C-4’),
[24b]
(196 mg, 512
mmol), K CO (71.0 mg, 512 mmol), Pd(PPh ) (20.0 mg, 17.1 mmol),
2
3
3 4
1
(
51.1 ppm (NCOO); FT-IR (ATR): ~n =2921 (s), 2852 (s), 1732 (s), 1614
w), 1584 (w), 1519 (w), 1462 (s), 1425 (w), 1406 (w), 1380 (w), 1351
purification method B; yield: 55 mg, 49.9 mmol, 29%, colorless solid;
1
H NMR (500 MHz, CDCl ): δ=0.89 (t, J=6.9 Hz, 6H; CH ), 1.21–1.41
3
3
(w), 1329 (w), 1252 (s), 1217 (w), 1199 (w), 1146 (w), 1124 (s), 1037
(w), 853 (w), 807 (w), 763 (w), 722 (w) cm ; MS (ESI): m/z=1340 [M
+
À 1
(m, 32H; CH
CH
(m, 2H; 6-H
2
), 1.43 (t, J=7.1 Hz, 6H; COOCH
2
CH
3
), 1.46–1.52 (m, 4H;
+
+
2
), 1.76–1.88 (m, 4H; CH
, 12-H ), 4.01 (t, J=6.6 Hz, 4H; OCH
2
2
), 3.38–3.45 (m, 2H; 6-H
a a
, 12-H ), 3.55-3.64
Na] ; HRMS (ESI): m/z calcd for C H N O +Na : 1339.9563 [M+
86 128 2 8
+ +
), 4.36–4.49 (m, 4H;
b
b
Na] , found: 1339.9490 [M+Na] .
COOCH ), 4.49–4.55 (m, 2H; 6a-H, 12a-H), 7.00 (d, J=9.6 Hz, 4H; 7’-
2
Diethyl (6aSR,12aSR)2,8-bis[3,4,5-tris(dodecyloxy)phenyl]-
H), 7.53 (dd, J=8.6, 1.9 Hz, 2H; 3-H, 9-H), 7.59 (d, J=9.6 Hz, 4H; 6’-
H), 7.66 (d, J=8.4 Hz, 4H; 3’-H), 7.73 (d, J=8.4 Hz, 4H; 2’-H), 7.75 (d,
6
,6a,12,12a-tetrahydropentaleno[2,1-b:5,4-b’]diindole-5,11-dicar-
1
3
boxylate (Ph-6m): According to GP3, from 12a (100 mg, 171 mmol),
J=1.9 Hz, 2H; 1-H, 7-H), 8.20 ppm (d, J=8.6 Hz, 2H; 4-H, 10-H);
C
[
18]
3
,4,5-tris(dodecyloxy)phenylboronic acid
(288 mg, 426 mmol),
NMR (126 MHz, CDCl ): δ=14.1 (CH ), 14.5 (COOCH CH ), 22.7, 26.1,
3
3
2
3
K CO (71.0 mg, 512 mmol), Pd(PPh ) (20.0 mg, 17.1 mmol), purifica-
29.3, 29.4, 29.4, 29.6, 29.6, 29.7, 29.7, 31.9 (CH ), 33.9 (C-6, C-12),
2
3
3 4
2
tion method A: chromatography with hexanes/EtOAc (50:1!1:1);
46.0 (C-6a, C-12a), 62.9 (COOCH ), 68.1 (OCH ), 114.9 (C-7’), 116.2 (C-
2
2
1
yield: 125 mg, 74.1 mmol, 43%, colorless solid, m.p. 77°C; H NMR
4, C-10), 116.6 (C-1, C-7), 122.6 (C-3, C-9), 126.6 (C-6b, C-12b), 126.9
(C-6c, C-12c), 127.0 (C-3’), 127.7 (C-2’), 128.0 (C-6’), 133.0 (C-5’),
135.9 (C-2, C-8), 139.5 (C-4’), 139.8 (C-4a, C-10a), 140.0 (C-1’), 142.6
(C-5a, C-11a), 151.1 (NCOO), 158.8 ppm (C-8’); FT-IR (ATR): ~n =2922
(s), 2852 (w), 1735 (s), 1609 (w), 1580 (w), 1529 (w), 1503 (w), 1461
(s), 1406 (w), 1379 (s), 1352 (w), 1332 (w), 1284 (w), 1249 (s), 1216
(w), 1204 (w), 1178 (w), 1123 (s), 1051 (w), 999 (w), 878 (w), 813 (s),
(500 MHz, CDCl ): δ=0.85–0.91 (m, 18H; CH ), 1.20–1.39 (m, 108H;
3 3
CH ), 1.43 (t, J=7.1 Hz, 6H; COOCH CH ), 1.47–1.56 (m, 12H; CH ),
2
2
3
2
3
.36–3.43 (m, 2H; 6-H , 12-H ), 3.53–3.63 (m, 2H; 6-H , 12-H ), 4.02 (t,
a a b b
J=6.6 Hz, 4H; p-OCH ), 4.05–4.12 (m, 8H; m-OCH ), 4.36–4.48 (m,
2
2
4
H; COOCH ), 4.48–4.53 (m, 2H; 6a-H, 12a-H), 6.83 (s, 4H; 2’-H), 7.44
2
(dd, J=8.6, 1.8 Hz, 2H; 3-H, 9H), 7.63 (d, J=1.8 Hz, 2H; 1-H, 7-H),
13
À 1
8.17 ppm (d, J=8.6 Hz, 2H; 4-H, 10-H); C NMR (126 MHz, CDCl3):
δ=14.1 (CH
764 (w), 705 (w), 621 (w), 519 (w) cm ; MS (MALDI-TOF): m/z calcd
+
), 14.4 (CO
CH
CH
2
), 22.7, 22.7, 26.2, 26.2, 29.4, 29.4,
3
for C74
H
N
2
O
6
: 1100.6, found: 1098.2; elemental analysis calcd (%)
3
2
88
Eur. J. Org. Chem. 2021, 1452–1465
www.eurjoc.org
1463
© 2021 The Authors. European Journal of Organic Chemistry published
by Wiley-VCH GmbH

Full Papers
doi.org/10.1002/ejoc.202001656
for C H N O : C 80.69, H 8.05, N 2.54; found: C 79.97, H 7.78, N Acknowledgement
7
4
88
2
6
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
À 1
À 1
2
.47. DSC: 193°C (30.2 kJmol ) SmA 207°C (60.1 kJmol ) N 303°C
I (decomp., 1. heating).
Generous financial support by the Ministerium für Wissenschaft,
Forschung und Kunst des Landes Baden-Württemberg, the Fonds
der Chemischen Industrie, the Deutsche Forschungsgemeinschaft
Diethyl (6aSR,12aSR)-2,8-bis(4’-(tetradecyloxy)-[1,1’-biphenyl]-4-
yl)-6,6a,12,12a-tetrahydropentaleno[2,1-b:5,4-b’]diindole-5,11-di-
carboxylate (Biph-6c): According to GP3, from 12a (250 mg, 426
(LA907/17-1 and shared instrumentation grant INST 41/897-1
[
24c]
mmol), 4’-(tetradecyloxy)-4-biphenylboronic acid
(525 mg,
FUGG for 700 MHz NMR), the Bundesministerium für Bildung und
Forschung (shared instrumentation grant 01 RI05177) and the
Carl-Schneider-Stiftung Aalen (shared instrumentation grant) are
gratefully acknowledged. We would like to thank Finn Schulz and
Christopher Schilling for their help during preparation of the
manuscript. Open access funding enabled and organized by
Projekt DEAL.
1.28 mmol), K CO (117 mg, 1.28 mmol), Pd(PPh (49.0 mg, 42.6
)
3 4
2
3
mmol), purification method B; yield: 213 mg, 184 mmol, 43%, color-
1
less solid; H NMR (700 MHz, CDCl ): δ=0.89 (t, J=7.0 Hz, 6H; CH ),
3
3
1
.23–1.40 (m, 40H; CH ), 1.43 (t, J=7.1 Hz, 6H; CO CH CH ), 1.45–
2
2
2
3
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
1.52 (m, 4H; CH ), 1.77–1.86 (m, 4H; CH ), 3.36–3.46 (m, 2H; 6-H , 12-
2
2
a
H ), 3.51–3.64 (m, 2H; 6-H , 12-H ), 4.01 (t, J=6.5 Hz, 4H; OCH ), 4.3–
a
b
b
2
4.48 (m, 4H; COOCH ), 4.49–4.52 (m, 2H; 6a-H, 12a-H), 6.99 (d, J=
2
8.6 Hz, 4H; 7’-H), 7.53 (dd, J=8.5, 1.9 Hz, 2H; 3-H, 9-H), 7.58 (d, J=
8
2
1
2
.6 Hz, 4H; 6’-H), 7.66 (d, J=8.2 Hz, 4H; 3’-H), 7.73 (d, J=8.2 Hz, 4H;
’-H), 7.74 (d, J=1.9 Hz, 2H; 1-H, 7-H), 8.17–8.22 ppm (m, 2H; 4-H,
1
3
0-H); C NMR (176 MHz, CDCl ): δ=14.1 (CH ), 14.5 (COOCH CH ), Conflict of Interest
3
3
2
3
2.7, 26.1, 29.3, 29.4, 29.4, 29.6, 29.6, 29.7, 29.7, 29.7, 29.7, 31.9
(CH ), 33.9 (C-6, C-12), 46.0 (C-6a, C-12a), 62.9 (COOCH ), 68.1
2
2
The authors declare no conflict of interest.
(OCH
), 114.8 (C-7’), 116.2 (C-4, C-10), 116.6 (C-1, C-7), 122.6 (C-3, C-
2
9
1
1
8
1
), 126.6 (C-6b, C-12b), 126.8 (C-6c, C-12c), 127.0 (C-3’), 127.6 (C-2’),
28.0 (C-6’), 133.0 (C-5’), 135.9 (C-2, C-8), 139.4 (C-4’), 139.8 (C-4a, C-
0a), 139.9 (C-1’), 142.5 (C-5a, C-11a), 151.1 (NCOO), 158.8 ppm (C-
’); FT-IR (ATR): ~n =2917 (w), 2848 (w), 1728 (w), 1605 (w), 1501 (w),
457 (s), 1403 (w), 1375 (w), 1353 (w), 1326 (s), 1267 (w), 1242 (s),
Keywords: Hydropentalene
Mesophases · Protecting groups
·
Indole
·
Liquid crystals
·
1213 (w), 1196 (w), 1175 (w), 1118 (s), 1032 (w), 998 (w), 815 (s), 766
(w), 723 (w), 704 (w), 669 (w), 524 (w), 432 (w) cm ; MS (MALDI-
TOF): m/z calcd for C H N O : 1156.72, found: 1155.1; elemental
analysis calcd (%) for C H N O : C 80.93, H 8.36, N 2.42; found: C
À 1
[
1] Reviews: a) Y. Yu, J.-S. Zhong, K. Xu, Y. Yuan, K.-Y. Ye, Adv. Synth. Catal.
2020, 362, 2102–2119; b) M. Vlasselaer, W. Dehaen, Molecules 2016, 21,
785/1–785/38; c) G. Sathiyan, E. K. T. Sivakumar, R. Ganesamoorthy, R.
Thangamuthu, P. Sakthivel, Tetrahedron Lett. 2016, 57, 243–252; d) A.
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Frutos, J. L. Serrano, A. Golemme, B. Gómez-Lor, Chem. Mater. 2013, 25,
+
78 96
2
6
7
8
96
2
6
À 1
8
0.80, H 8.20, N 2.30. DSC: 168°C (16.3 kJmol ) SmA 193°C
À 1
(
33.9 kJmol ) N 301°C I (decomp., 1. heating).
Diethyl (6aSR,12aSR)-2,8-bis(4’-(hexadecyloxy)-[1,1’-biphenyl]-4-
yl)-6,6a,12,12a-tetrahydropentaleno[2,1-b:5,4-b’]diindole-5,11-di-
carboxylate (Biph-6d): According to GP3, from 12a (250 mg, 426
mmol), 4’-(hexadecyloxy)-4-biphenylboronic acid
1.28 mmol), K CO3 (117 mg, 1.28 mmol), Pd(PPh3)4 (49.0 mg, 42.6
mmol), purification method B; yield: 120 mg, 98.9 mmol, 23%,
colorless solid; H-NMR (700 MHz, CDCl ): δ=0.88 (t, J=7.1 Hz, 6H;
CH ), 1.22–1.41 (m, 40H; CH ), 1.44 (t, J=7.1 Hz, 6H; COOCH CH ),
1
H , 12-H ), 3.56–3.63 (m, 2H; 6-H , 12-H ), 4.02 (t, J=6.6 Hz, 4H;
OCH ), 4.38–4.50 (m, 4H; COOCH ), 4.50–4.56 (m, 2H; 6a-H, 12a-H),
7.00 (d, J=8.7 Hz, 4H; 7’'-H), 7.54 (dd, J=8.6, 1.8 Hz, 2H; 3-H, 9-H),
7.60 (d, J=8.7 Hz, 4H; 6’'-H), 7.67 (d, J=8.2 Hz, 4H; 3’'-H), 7.72–7.77
[24c]
(561 mg,
[
2
117–121; b) E. M. García-Frutos, A. Omenat, J. Barberá, J. L. Serrano, B.
1
3
Gómez-Lor, J. Mater. Chem. 2011, 21, 6831–6836; c) E. M. García-Frutos,
B. Gómez-Lor, Proc. SPIE (Eds.: Z. Bao, I. McCulloch), 2009; Vol. 7417, p
74170J–74170J-9; d) M. Talarico, R. Termine, E. M. García-Frutos, A.
Omenat, J. L. Serrano, B. Gómez-Lor, A. Golemme, Chem. Mater. 2008,
20, 6589–6591; e) B. Gómez-Lor, B. Alonso, A. Omenat, J. L. Serrano,
Chem. Commun. 2006, 5012–5014.
3] a) R. Zhang, X. Zeng, B. Kim, R. J. Bushby, K. Shin, P. J. Baker, V. Percec, P.
Leowanawat, G. Ungar, ACS Nano 2015, 9, 1759–1766; b) V. Percec, M.
Glodde, M. Peterca, A. Rapp, I. Schnell, H. W. Spiess, T. K. Bera, Y. Miura,
V. S. K. Balagurusamy, E. Aqad, Chem. Eur. J. 2006, 12, 6298–6314; c) V.
Percec, M. Glodde, T. K. Bera, Y. Miura, I. Shiyanovskaya, K. D. Singer,
V. S. K. Balagurusamy, P. J. Heiney, Polym. Prepr. 2002, 43, 402–403.
3
2
2
3
.46–1.52 (m, 4H; CH ), 1.78–1.87 (m, 4H; CH ), 3.39–3.46 (m, 2H; 6-
2
2
a
a
b
b
2
2
[
1
3
(
(
m, 6H; 1-H, 7-H, 2’'-H), 8.18–8.24 ppm (m, 2H; 4-H, 10-H); C NMR
176 MHz, CDCl ): δ=14.2 (CH ), 14.5 (COOCH CH ), 22.7, 26.1, 29.3,
3
3
2
3
2
6
1
9.4, 29.4, 29.6, 29.7, 29.7 (CH ), 31.9 (C-6, C-12), 46.0 (C-6a, C-12a),
2
2.9 (COOCH ), 68.1 (OCH ), 114.8 (C-7’), 116.2 (C-4, C-10), 116.6 (C-
2
2
[4] a) S.-I. Kawano, M. Kato, S. Soumiya, M. Nakaya, J. Onoe, K. Tanaka,
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1
(
(
(
NCOO), 158.8 ppm (C-8’); FT-IR (ATR): ~n =2919 (s), 2849 (w), 1730
s), 1607 (w), 1502 (w), 1459 (s), 1405 (w), 1377 (s), 1353 (w), 1327
s), 1270 (w), 1245 (s), 1214 (w), 1177 (w), 1120 (s), 1048 (w), 816 (s),
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À 1
7
66 (w), 724 (w), 704 (w), 525 (w) cm ; MS (MALDI-TOF): m/z calcd
+
for C H N O6 : 1212.78, found: 1209.9; elemental analysis calcd
82
104
2
(%) for C82
H
N O : C 81.15, H 8.64, N 2.31; found: C 81.25, H 8.41,
104 2 6
À 1
À 1
N 2.41. DSC: 154°C (19.2 kJmol ) SmA 196°C (29.3 kJmol ) N
3
04°C I (decomp., 1. heating).
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Eur. J. Org. Chem. 2021, 1452–1465
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1464
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by Wiley-VCH GmbH

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[
Manuscript received: January 3, 2021
Revised manuscript received: January 27, 2021
Accepted manuscript online: January 29, 2021
[
crystallographic data for this paper. These data are provided free of
Eur. J. Org. Chem. 2021, 1452–1465
www.eurjoc.org
1465
© 2021 The Authors. European Journal of Organic Chemistry published
by Wiley-VCH GmbH