Improved Access to 1,8-Dichloro-10-(ethynyl)anthracene: A Useful Building Block for (Semi-)rigid Organic Frameworks

Article abstract of DOI:10.1055/s-0036-1591925

An easy access to 1,8-dichloro-10-(ethynyl)anthracene is reported, which is widely applicable for building up rigid linkers between two 1,8-dichloroanthracene units. For this, 1,8-dichloroanthren-10(9 H)-one was reacted with ethynylmagnesium bromide in the presence of CeCl ₃; the yield was 65%. This building block was used as a substrate in (cross-)coupling reactions and some examples of linked 1,8-dichloroanthracen-10-yls (e.g., 1,8-bis[(1,8-dichloroanthracen-10-yl)-ethynyl]naphthalene or 1,2-bis[(1,8-dichloroanthracen-10-yl)ethynyl]-benzene) were synthesized in good to moderate yields. Linked 1,8-dichloroanthracen-10-yl derivatives were also synthesized by cross-coupling reactions using 10-bromo-1,8-dichloroanthracene and doubly ethynyl-substituted substrates. Linkers between the 1,8-dichloroanthracene units were: butadiynediyl, dimethylsilyldiethynyl, octa-1,7-diyne-1,8-diyl, propane-1,3-diylbis(dimethylsilyl)diethynyl, benzene-1,2-diethynyl, naphthalene-1,8-diyldiethynyl, and anthracene-1,8-diyldiethynyl. The new anthracene compounds were characterized by NMR spectroscopy, high-resolution mass spectrometry, and, in part, by X-ray diffraction experiments.

Full text of DOI:10.1055/s-0036-1591925

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2018, 50, A–J
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J.-H. Lamm et al.
Paper
Synthesis
Improved Access to 1,8-Dichloro-10-(ethynyl)anthracene:
A Useful Building Block for (Semi-)rigid Organic Frameworks
Jan-Hendrik Lamm‡
Philipp Niermeier‡
Leif A. Körte
Beate Neumann
Hans-Georg Stammler
Norbert W. Mitzel*
Universität Bielefeld, Fakultät für Chemie, Lehrstuhl für
Anorganische Chemie und Strukturchemie, Centrum für
Molekulare Materialien CM2, Universitätsstraße 25, 33615
Bielefeld, Germany
mitzel@uni-bielefeld.de
‡ These authors contributed equally to this work.
Received: 05.12.2017
Accepted after revision: 11.01.2018
Published online: 06.02.2018
DOI: 10.1055/s-0036-1591925; Art ID: ss-2017-t0787-op
Abstract An easy access to 1,8-dichloro-10-(ethynyl)anthracene is re-
ported, which is widely applicable for building up rigid linkers between
two 1,8-dichloroanthracene units. For this, 1,8-dichloroanthren-
10(9H)-one was reacted with ethynylmagnesium bromide in the pres-
A
B
C
ence of CeCl3; the yield was 65%. This building block was used as a sub-
strate in (cross-)coupling reactions and some examples of linked 1,8-di-
chloroanthracen-10-yls (e.g., 1,8-bis[(1,8-dichloroanthracen-10-yl)-
ethynyl]naphthalene or 1,2-bis[(1,8-dichloroanthracen-10-yl)ethynyl]-
benzene) were synthesized in good to moderate yields. Linked 1,8-di-
chloroanthracen-10-yl derivatives were also synthesized by cross-cou-
pling reactions using 10-bromo-1,8-dichloroanthracene and doubly
ethynyl-substituted substrates. Linkers between the 1,8-dichloroan-
thracene units were: butadiynediyl, dimethylsilyldiethynyl, octa-1,7-
diyne-1,8-diyl, propane-1,3-diylbis(dimethylsilyl)diethynyl, benzene-
1,2-diethynyl, naphthalene-1,8-diyldiethynyl, and anthracene-1,8-di-
yldiethynyl. The new anthracene compounds were characterized by
NMR spectroscopy, high-resolution mass spectrometry, and, in part, by
X-ray diffraction experiments.
Figure 1 Examples of rigid organic frameworks consisting of alkyne-
linked aryls by Eglinton (A),1a Tobe (B)2 and Toyota (C)3
In the course of our investigations in the field of poly-
Lewis acids with rigid organic frameworks,9a,b we have to
make use of donor-atom-free organic backbones with di-
rected functionalities. Latterly, we have used 1,8-substitut-
ed anthracene derivatives and synthesized bidentate Al, Ga,
and In Lewis acids with almost parallelly oriented earth
metal acceptor functions.9 Their use as Lewis acidic recep-
tor molecules in host-guest chemistry has been demon-
strated.9c,10 In order to increase the number of oriented
functions, we found that systems with two 1,8-dichloro-
anthracene units donor-freely linked in the 10-position are
desirable synthetic targets (Scheme 1).
Key words anthracenes, alkynes, rigid organic frameworks, cross-
coupling reactions, solid-state structures
Rigid organic frameworks consisting of alkyne-linked
aryl units are widely utilized in many fields of (synthetic)
chemistry. The corresponding molecules are of structural
interests, like those shown in Figure 1.1–3
Cl
Cl
Cl
Cl
Cl
Cl
linker
They also find versatile applications in supramolecular
chemistry, e.g. as host structures in host-guest chemistry,4
in creating nanoscale 3D structures with large interior
space,5 as building blocks in shape-persistent, fluorescent
or through-space conjugated polymers,6 in sensors7 or in
light-emitting diodes (LEDs).8 Further applications of these
(conjugated) backbones are conceivable, especially when
the aryl rings are substituted with atoms or groups allow-
ing further functionalizations.
H
linker
4
Scheme 1 Schematic drawing of two linked 1,8-dichloro-10-
(ethynyl)anthracene units
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–J

B
J.-H. Lamm et al.
Paper
Synthesis
Herein we report an efficient route to 1,8-dichloro-10-
(ethynyl)anthracene (4) and demonstrate some examples
to join two of these units using different linker systems.
These systems allow the variation of the orientation of the
C–Cl functions from 180° to almost parallel. Further func-
tionalization of these backbones is optional, but not report-
ed in this work.
Cl
O
Cl
i)
ii)
O
Cl
Cl
Cl
Cl
1
As shown in Scheme 2, 1,8-dichloro-10-(ethynyl)-
anthracene (4) can be synthesized using various multistep
routes starting from commercially available 1,8-dichloro-
anthraquinone (1). We recently reported the synthesis of
3
O
2
iv)
v)
iii)
Cl
Cl
Cl
Cl
Cl
Cl
1,8-dichloro-10-[(trimethylsilyl)ethynyl]anthracene
(5),
vii)
vi)
the SiMe3-protected form of the desired species 4, by con-
version of the 1,8-dichloroanthracen-10(9H)-one (2) with
[(trimethylsilyl)ethynyl]magnesium bromide.11 Compound
5 was also obtained by a Sonogashira–Hagihara cross-cou-
pling reaction using 10-bromo-1,8-dichloroanthracene
(6).12 The latter can be prepared from 1,8-dichloroanthra-
cene (3) with elemental bromine in quantitative yield.13
Cleaving off the TMS group by a standard protocol affords
1,8-dichloro-10-(ethynyl)anthracene (4) in an overall yield
of 53% starting from 214 and 84% starting from 3.
Br
6
H
Si
4
5
Scheme 2 Various synthetic routes for 1,8-dichloro-10-(ethynyl)an-
thracene (4). Reagents and conditions: (i) Na2S2O4, DMF, H2O, 90 °C, 4 h,
92%;16 (ii) 1. Zn, aq NH3; 2. HCl, i-PrOH, 85%;17 (iii) HC≡CMgBr, CeCl3,
THF, 0 °C to r.t., overnight, 65%; (iv) 1. Me3SiC≡CMgBr (3 equiv), Et2O,
r.t. overnight; 2. aq workup, 56%;11,14 (v) Br2, CH2Cl2, 0 °C to r.t.,
quant.;13 (vi) 1. Me3SiC≡CH (2 equiv), CuI (10 mol%), PdCl2(PPh3)2 (5
mol%), i-Pr2NH, reflux, 3d; 2. aq workup, 89%; (vii) K2CO3, MeOH, r.t.,
94%.
A new and efficient single step access to compound 4 is
provided by a CeCl3-promoted conversion of anthrone 2
with ethynylmagnesium bromide in THF (yield: 65% start-
ing from 2). Imamoto and co-workers demonstrated in
1989 that the addition of CeCl3 improves the addition of
Grignard reagents to ketones by suppressing side reac-
tions.15 The presence of the cerium salt seems to be import-
ant, since the yield of 4 is remarkably lower (14%), when
the reaction is carried out under the same conditions in the
absence of CeCl3.
Compounds 7 and 10 were synthesized in good to mod-
erate yields by Sonogashira–Hagihara cross-coupling reac-
tions with 1,8-diiodonaphthalene and 1,2-diiodobenzene
as aryl halide species. In all cases, the extreme low solubili-
ty of the obtained products 7 and 9 in common organic sol-
vents, polar as well as non-polar ones, caused serious prob-
lems in recording NMR spectra. Notwithstanding, the com-
pounds were identified and their successful synthesis was
1
Compound 4 was identified by H and 13C NMR spec-
troscopy, as well as by (high resolution) mass spectrometry.
Its 1H NMR spectrum recorded at ambient temperature
(298 K) in CDCl3 shows the typical set of resonances for
1,8,10-substituted anthracene derivatives. It contains one
singlet at 9.35 (H9), two doublets at 8.53 (H4/H5) and 7.68
(H2/H7), and one doublet of doublets at 7.53 (H3/H6). The
singlet at 4.03 is caused by the ethynyl proton.
As described above, the deprotected species 4 can be
used to construct rigid organic frameworks with directed
chloro substituents, allowing further functionalization. As
displayed in Scheme 3, we used (cross-)coupling reactions
to synthesize such fourfold chlorine-substituted organic
backbones, whereby the direction of the C–Cl functions can
be varied from nearly parallel orientation (in 7) to anti-
parallel (ca. 180° in 9).
1
proven by at least H NMR spectroscopy and (high-resolu-
tion) mass spectrometry.
To increase the solubility compared to that of 10, two
n-hexyl moieties were introduced into the linker unit
(Scheme 3). Starting from 1,2-dichlorobenzene, 1,2-dihex-
yl-4,5-diiodobenzene was synthesized in analogy to a liter-
ature protocol in a two-step reaction via 1,2-dihexyl-
benzene.19 In fact, 11 shows a much better solubility than
1
10 and can be purified by column chromatography. The H
NMR spectrum recorded at ambient temperature (298 K) in
CDCl3 shows an anthracene signal pattern being compara-
ble with that of compound 4, whereby the anthracene reso-
nances are slightly shifted. Besides these signals a singlet at
7.66 can be assigned to the two protons at the benzene unit
and broad multiplet signals at 2.74, 1.70, 1.42, and 0.94 are
observed for the overall 26 protons of the n-hexyl substitu-
ents.
The butadiynyl-linked species 9 was obtained in excel-
lent yield by a Cu-mediated oxidative Eglinton coupling re-
action using copper(II) acetate and a mixture of diethyl
ether, methanol, and pyridine as the solvent.18
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J.-H. Lamm et al.
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Synthesis
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
7
Si
i)
8
ii)
Cl
Cl
Cl
Cl
iii)
H
4
iv)
Cl
Cl
R
Figure 2 Different views of the molecular structure of 11 in the crys-
talline state. Displacement ellipsoids are drawn at the 50% probability
level, hydrogen atoms are omitted for clarity. The side view (below) il-
lustrates the orthogonality of the anthracene units. Selected bond
lengths (Å) and angles: C(1)–C(2) 1.433(2), C(1)–C(14) 1.354(2), C(1)–
Cl(1) 1.742(1), C(2)–C(3) 1.396(2), C(2)–C(11) 1.438(2), C(10)–C(11)
1.411(2), C(10)–C(15) 1.434(2), C(15)–C(16) 1.200(2), C(16)–C(17)
1.429(2), C(17)–C(18) 1.401(2), C(17)–C(42) 1.407(2), C(18)–
C(19)1.388(2), C(19)–C(20) 1.509(2), C(19)–C(44) 1.416(2); C(1)–
C(2)–C(3) 123.5(1)°, C(1)–C(2)–C(11) 116.9(1)°, C(2)–C(1)–Cl(1)
118.8(1)°, C(9)–C(10)–C(11) 121.2(1)°, C(9)–C(10)–C(15) 119.4(1)°,
C(10)–C(15)–C(16) 177.6(1)°, C(15)–C(16)–C(17) 177.0(1)°, C(16)–
C(17)–C(18) 119.9(1)°, C(17)–C(18)–C(19) 121.9(1)°, C(18)–C(19)–
C(20) 121.8(1)°, C(18)–C(19)–C(44) 119.0(1)°.
R
Cl
Cl
Cl
9
10 R = H
11 R = n-Hex
Cl
Scheme 3 Use of 1,8-dichloro-10-(ethynyl)anthracene (4) as a precur-
sor for rigid organic frameworks. Reagents and conditions: (i) 1,8-
diiodonaphthalene, PdCl2(PPh3)2, CuI, i-Pr2NH, r.t., 15 h; 2. aq workup,
63%; (ii) 1. BuLi, THF, –78 °C, 1 h; 2. Me2SiCl2, r.t. 12 h; 3. aq workup,
73%; (iii) Cu(OAc)2, Et2O/MeOH/pyridine (4:1:1), reflux, 2 h, 92%; (iv)
synthesis of 10: 1,2-diiodobenzene, PdCl2(PPh3)2, CuI, i-Pr2NH, r.t., 15
h; 2. aq workup, 83%; synthesis of 11: 1,2-dihexyl-4,5-diiodobenzene,
PdCl2(PPh3)2, CuI, i-Pr2NH, r.t., 18 h; 2. aq workup, 60%.
Single crystals of 1,2-bis[(1,8-dichloroanthracen-10-
yl)ethynyl]-4,5-dihexylbenzene (11) were obtained by slow
evaporation of the solvent after column chromatography.
Its molecular structure was determined by X-ray diffraction
and is depicted in Figure 2.
cal within experimental error, well comparable with the
corresponding C≡C triple bond length in 5 [1.208(3) Å12]
and conform to the standard C≡C triple bond length (1.20
Å20). The alkynyl group of the orthogonally twisted anthra-
cene substituent is slightly more distorted from linearity as
is indicated in the corresponding angles {177.6(1)° [C(10)–
C(15)–C(16)] vs. 179.0(1)° [C(35)–C(40)–C(41)] and
177.0(1)° [C(15)–C(16)–C(17)] vs. 178.9(1) [C(40)–C(41)–
C(42)]}. Distances and angles at the central benzene ring
are not markedly influenced by the substituents in 1-, 2-, 4-
and 5-position as the C–C distances vary just marginally
from that of benzene (1.395 Å21). With C–C–C angles rang-
ing from 119.0(1)° [C(18)–C(19)–C(44)] to 121.8(1)°
[C(18)–C(19)–C(20)] all quaternary benzene carbon atoms
are trigonal-planar coordinated.
Compound 11 crystallizes in the triclinic space group P1
with two molecules per unit cell. As illustrated in the struc-
ture side view (Figure 2, below), one anthracene unit is al-
most coplanar with the central benzene ring [angle be-
tween their mean planes: 2.4(1)°], whereas the second an-
thracene substituent is found to be nearly orthogonal to the
other benzene ring as is indicated by the 86.8(1)° angle be-
tween their mean planes. The four chlorine atoms are found
to be in-plane with the adjacent anthracene units. The an-
thracene units themselves exhibit the expected bond
lengths and angles, the structural parameters being well
comparable with those of the previously reported SiMe3 de-
rivative 5.11 The bond lengths C(15)–C(16) and C(40)–C(41)
are 1.200(2) Å and 1.203(2) Å, respectively. They are identi-
In the case of the conversion of 1,8-dichloro-10-
(ethynyl)anthracene (4) with the diiodobenzene derivatives
we were capable of isolating the corresponding mono-
alkynyl-substituted species 10a by sublimation and 11a by
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J.-H. Lamm et al.
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Synthesis
column chromatography. We also determined the molecu-
lar structures of compounds 10a and 11a by X-ray crystal-
lography; they are displayed in Figure 3.
within experimental error. All mentioned distances and an-
gles of the (alkynyl-)dichloroanthracene unit are well com-
parable with those observed in various other 10-substitut-
ed 1,8-dichloroanthracene derivatives.11,13
Table 1 Selected Bond Lengths and Angles of the Mono-iodine
Compounds 10a and 11a
Bonds and angles
Bond lengths (Å) or angles
10a
11a
1.429(2)
C(1)–C(2)
1.428(5)
1.354(6)
1.743(4)
1.411(6)
1.427(6)
1.415(6)
1.431(6)
1.201(6)
1.428(6)
1.410(5)
1.446(6)
2.091(4)
1.368(6)
123.4(4)°
117.2(4)°
119.4(4)°
177.5(5)°
175.4(4)°
122.4(4)°
120.6(3)°
C(1)–C(14)
1.361(2)
1.741(2)
1.396(2)
1.435(2)
1.413(2)
1.429(2)
1.202(2)
1.428(2)
1.396(2)
1.410(2)
2.092(2)
1.393(2)
122.8(1)°
117.0(1)°
119.7(1)°
178.4(2)°
176.0(2)°
123.5(1)°
121.0(1)°
C(1)–Cl(1)
C(2)–C(3)
C(2)–C(11)
C(9)–C(10)
C(10)–C(15)
C(15)–C(16)
C(16)–C(17)
C(17)–C(18)
C(17)–C(22)
C(18)–I(1)
C(19)–C(20)
C(1)–C(2)–C(3)
C(1)–C(2)–C(11)
C(9)–C(10)–C(15)
C(10)–C(15)–C(16)
C(15)–C(16)–C(17)
C(16)–C(17)–C(18)
C(17)–C(18)–I(1)
Figure 3 Molecular structure of the mono-iodine compounds 10a
(above) and 11a (below) in the crystalline state. Displacement ellipsoids
are drawn at the 50% probability level, hydrogen atoms are omitted for
clarity. Selected bond lengths and angles are listed in Table 1.
In contrast to the synthetic (cross-coupling) pathways
described above, we isolated bis[(1,8-dichloroanthracen-
10-yl)ethynyl]dimethylsilane (8) after deprotonation of the
ethynyl function of 10-ethynyl-1,8-dichloroanthracene (4)
and subsequent conversion with dichlorodimethylsilane.
Owing to the fact, that similar structural parameter val-
ues are observed for 10a and 11a, their molecular struc-
tures are described together. In contrast to the molecular
structure of 11 described above, the two aromatic ring sys-
tems of the mono-iodine species 10a and 11a are found to
be not exactly coplanar. The angles between the corre-
sponding mean planes are 9.4(1)° (10a) and 5.1(1)° (11a),
obviously differing from that of 11 [2.4(1)°]. As observed in
the case of 11, the chlorine atoms of 10a and 11a (as well as
the iodine atoms) are in-plane with the aromatic ring sys-
tems. All bond lengths and angles are within the expected
range (Table 1), so only two selected structural parameters
deserve detailed comments. As is exemplarily indicated in
the distances C(19)–C(20) [1.368(6) (10a) vs. 1.393(2) Å
(11a)] and C(17)–C(22) [1.446(6) (10a) vs. 1.410(2) Å
(11a)], the geometry of the central benzene ring seems to
be affected by the n-hexyl substituents, whereby a signifi-
cant aberration is observed in the latter case. The dichloro-
anthracene and alkyne values are found to be identical
1
The desired compound was clearly identified by H NMR
spectroscopy, showing the typical anthracene signal pat-
tern described above; EI (high-resolution) mass spectrome-
try experiments also confirm the formation of 8. After
recrystallization from benzene, single crystals, suitable for
X-ray diffraction experiments, were obtained in 73% yield.
The dimethylsilylethynyl-bridged compound 8 crystallizes
in the monoclinic space group C2/c with four molecules per
unit cell, i.e. it is located on a twofold axis. Its molecular
structure in the crystalline state is depicted in Figure 4,
showing that the chlorine functionalities of the different
anthracene units almost point in perpendicular orientation.
The twist angle between the mean planes of the aromatic
ring systems is 15.1° (Figure 4, below). The alkyne units are
distorted from linearity as it is indicated by the C(15)–
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J.-H. Lamm et al.
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Synthesis
C(16)–Si(1) angle [169.3(1)°]. All other bond lengths and
angles are found to be in a normal range and identical with-
in experimental error with 1,8-dichloro-10-[(trimethyl-
silyl)ethynyl]anthracene (5).11
chloroanthracenes in 12 are found to be in normal ranges.
The C≡C–C/C≡C–Si units [d(C≡C): 1.202(3) and 1.209(3) Å,
respectively] are close to linearity as it is indicated by the
corresponding C–C–C and C–C–Si angles ranging from
177.0(2)° to 178.8(2)°. The two Si atoms are connected by a
propylene bridge of twisted zigzag structure. The torsion
angle C(21)–C(20)–C(19)–Si(1) is found to be –58.6(2)°
[vs. C(19)–C(20)–C(21)–Si(2): –171.5(1)°].
Cl
Cl
Cl
Cl
Cl
Cl
Si
Cl
Si
Cl
12
i)
ii)
Br
6
iii)
Cl
Cl
Cl
Cl
Cl
Cl
13
Figure 4 Different views of the molecular structure of 8 in the crystal-
line state. Displacement ellipsoids are drawn at the 50% probability lev-
el, hydrogen atoms are omitted for clarity. The side view (below)
illustrates the bending of the alkyne units and the twist angle between
the anthracene mean planes (15.1°). Selected bond lengths (Å) and an-
gles: C(1)–C(2) 1.431(2), C(1)–C(14) 1.360(2), C(1)–Cl(1) 1.738(2),
C(2)–C(3) 1.396(2), C(2)–C(11) 1.435(2), C(10)–C(11) 1.418(2),
C(10)–C(15) 1.431(2), C(15)–C(16) 1.207(2), C(16)–Si(1) 1.829(2),
C(17)–Si(1) 1.855(2); C(1)–C(2)–C(3) 122.8(1)°, C(1)–C(2)–C(11)
117.3(1)°, C(2)–C(1)–Cl(1) 119.0(1)°, C(9)–C(10)–C(11) 121.1(1)°,
C(9)–C(10)–C(15) 119.6(1)°, C(10)–C(15)–C(16) 177.5(2)°, C(15)–
C(16)–Si(1) 169.3(2)°, C(16)–Si(1)–C(16′) 106.7(1)°, C(16)–Si(1)–C(17)
112.5(1)°.
C6H13
R =
R
14
Scheme 4 Use of 10-bromo-1,8-dichloroanthracene (6) as a precursor
for rigid organic frameworks. Reagents and conditions: (i) 1. 1,3-
bis(ethynyldimethylsilyl)propane, CuI, PdCl2(PPh3)2, i-Pr2NH, reflux, 4 d;
2. aq workup, 48%; (ii) 1. octa-1,7-diyne, CuI, PdCl2(PPh3)2, i-Pr2NH, re-
flux, 4 d; 2. aq workup, 72%; (iii) 1. 17, CuI, PdCl2(PPh3)2, i-Pr2NH, reflux,
5 d; 2. aq workup, 20%.
We also used 10-bromo-1,8-dichloroanthracene (6) to
construct organic frameworks bearing two dichloroanthra-
cene subunits (Scheme 4). The semi-rigid compounds 12
and 13 were obtained in Sonogashira–Hagihara cross-cou-
pling reactions by converting 6 with 1,3-bis(ethynyldi-
methylsilyl)propane (see the Supporting Information for
synthesis) and octa-1,7-diyne, respectively. Both species
show a good solubility in organic solvents and could be
completely characterized by multinuclear NMR spectrosco-
py, (high-resolution) mass spectrometry, and X-ray diffrac-
tion experiments (see Figure 5 for 12 and Figure S1, Sup-
porting Information, for 13). 12 crystallizes in the triclinic
space group P1 with two molecules per unit cell. As already
observed in 8 and 11, the bond lengths and angles of the di-
A directed orientation of the four chlorine atoms is pro-
vided by a twofold Sonogashira–Hagihara cross coupling re-
action of 6 with 1,8-diethynyl-10-(oct-1-ynyl)anthracene
(17) which can be synthesized in three steps from 10-bromo-
1,8-dichloroanthracene [6; Scheme 5; see the Supporting
Information for experimental details (Scheme S2) and solid
state structures of 15 (Figure S2), 16 (Figure S3), and 17
(Figure S4)].
Although 14 is equipped with a potential solubility pro-
moting octynyl substituent, it turned out to be scarcely sol-
uble in organic solvents at ambient temperature. Anyhow,
14 was undoubtedly identified by multinuclear NMR and
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Si
Si
Si
Si
H13C6
UV
C6H13
2
C6H13
16
Si
Si
16a
Scheme 6 UV light-induced photodimerization of 16 yielding the
[4π+2π] cycloaddition byproduct 16a
duced photodimerization reaction yielding the cycloaddi-
tion product 16a (Scheme 6).
Figure 5 Molecular structure of 12 in crystalline state. Displacement
ellipsoids are drawn at 50% probability level, hydrogen atoms are omit-
ted for clarity. Selected bond lengths (Å) and angles: C(1)–C(2)
1.432(2), C(1)–C(14) 1.356(3), C(1)–Cl(1) 1.739(2), C(2)–C(3)
1.388(3), C(2)–C(11) 1.442(2), C(10)–C(11) 1.413(2), C(10)–C(15)
1.439(2), C(15)–C(16) 1.202(3), C(16)–Si(1) 1.840(2), C(17)–Si(1)
1.867(2), C(19)–Si(1) 1.877(2), C(19)–C(20) 1.356(2); C(1)–C(2)–C(3)
123.3(2)°, C(1)–C(2)–C(11) 116.8(2)°, C(2)–C(1)–Cl(1) 118.4(1)°, C(9)–
C(10)–C(11) 121.4(2)°, C(9)–C(10)–C(15) 119.4(1)°, C(10)–C(15)–
C(16) 177.3(2)°, C(15)–C(16)–Si(1) 177.0(2)°, C(16)–Si(1)–C(19)
108.4(1)°, C(18)–Si(1)–C(19) 111.9(1)°, C(19)–C(20)–C(21) 114.2(2)°,
C(20)–C(19)–Si(1) 116.8(1)°, C(20)–C(21)–Si(2) 112.6(1)°.
Such [4π+2π] cycloadditions are known for anthracene
derivatives, particularly for those bearing alkynyl substitu-
ents in the 10 position.22 The photodimer was clearly iden-
tified by NMR spectroscopy (see the Supporting Informa-
tion) and by X-ray diffraction experiments (Figure 6).
The photodimer 16a crystallizes in the monoclinic
space group P21/n with four molecules per unit cell. As it
can be seen from Figure 6, an intermolecular dimerization
took place. An octynyl unit of one molecule underwent a
[4π+2π] cycloaddition reaction with the central anthracene
ring of a second molecule. This results in a remarkable
elongation of the former C≡C bond [C(57)–C(58): 1.336(4) Å
vs. C(25)–C(26): 1.197(4) Å]. The folding angle between the
two isolated aromatic systems is 60.4(1)°, whereas all car-
bon atoms of the intact anthracene system found to be in
the mean plane (RMSD: 0.045 Å). All C≡C–C/C≡C–Si units
[d(C≡C): 1.204(5)–1.209(5) Å] are remarkably bent from
linearity as it is indicated by the corresponding C≡C–CAr and
C≡C–Si angles ranging from 169.3(3)° [C(52)–C(53)–Si(4)]
to 177.4(4)° [C(37)–C(52)–C(53)]. With C–C–C angles rang-
ing from 104.6(2)° to 106.2(2)°, the two bridgehead atoms
C(3) and C(10) exhibit a distorted tetrahedral coordination
geometry.
In conclusion, 1,8-dichloro-10-(ethynyl)anthracene (4),
a highly conjugated anthracene containing species, was af-
forded by the reaction of 1,8-dichloroanthracen-10(9H)-
one (2) with ethynylmagnesium bromide in one step,
whereby addition of cerium(III) chloride led to a remark-
able increase in yield. Compound 4 was demonstrated to be
a useful building block in the formation of rigid organic
backbones for (cross-)coupling reactions. A serious restric-
tion in applicability of most of these linked products is their
(extremely) low solubility in organic solvents. This problem
was exemplarily solved in one case by the introduction of
long-chain alkyl groups. 10-Bromo-1,8-dichloroanthracene
(6) was also used to form (semi-)rigid organic frameworks
R'
R'
Cl
Cl
Cl
Cl
i)
ii)
R
Br
R
6
15
R' = SiMe3 (16)
iii)
R' = H (17)
C6H13
R =
Scheme 5 Synthesis of 1,8-diethynyl-10-(oct-1-ynyl)anthracene (17)
starting from 10-bromo-1,8-dichloroanthracene (6). Reagents and con-
ditions: (i) 1. oct-1-yne, CuI, PdCl2(PPh3)2, i-Pr2NH, reflux, 4 d; 2. aq
workup, 84%; (ii) Me3SiC≡CMgBr (9 equiv), Ni(acac)2, PPh3, THF, reflux,
4 d; 2. aq workup, 83%; (iii) K2CO3, MeOH, r.t., 1 d, 67%. See the Sup-
porting Information for further details and solid state structures of 15,
16, and 17 (Figures S2, S3, and S4).
1
MALDI MS experiments. The H NMR spectrum of 14 con-
tains two sets of 1,8,10-trisubstituted anthracene reso-
nances and five signals for the terminal hexyl chain.
During our attempts to synthesize the desired com-
pound, we observed that the bis[(trimethylsilyl)ethynyl]
precursor 16 is obviously able to undergo a UV light-in-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–J

G
J.-H. Lamm et al.
Paper
Synthesis
1,8-Dichloroanthracen-10(9H)-one (2),16 1,2-dihexyl-4,5-diiodoben-
zene,19 and 1,8-diiodonaphthalene23 were synthesized according to
literature protocols. For the synthesis of 1,3-bis(ethynyldimethylsi-
lyl)propane, 1,8-dichloro-10-(oct-1-ynyl)anthracene (15), 1,8-
bis[(trimethylsilyl)ethynyl]-10-(oct-1-ynyl)anthracene (16), and 1,8-
diethynyl-10-(oct-1-ynyl)anthracene (17) see the Supporting Infor-
mation. Ethynylmagnesium bromide solution (0.5 M in THF) was pur-
chased from Sigma Aldrich, anhyd CeCl3 (purchased from Strem
Chemicals) was used without further purification. All reactions using
metal organic reagents were carried out under an anhydrous, inert at-
mosphere of N2 using standard Schlenk techniques in dry THF (dried
over potassium and freshly distilled before use). Column chromatog-
raphy was performed on silica gel 60 (0.04–0.063 mm). NMR spectra
were recorded on Bruker Avance III 300, a Bruker DRX 500, and a
Bruker Avance III 500 instruments at 298 K and referenced to solvent
1
1
(CDCl3: H NMR δ = 7.26, 13C NMR δ = 77.16; C6D6: H NMR δ = 7.16,
13C NMR δ = 128.06) or referenced externally (29Si NMR: TMS). EI-MS
were recorded using an Autospec X magnetic sector mass spectrome-
ter with EBE geometry (Vacuum Generators, Manchester, UK)
equipped with a standard EI source. MALDI TOF mass spectra were
recorded with a Voyager DE Instrument (PE Biosystems GmbH, Weit-
erstadt, Germany) and ESI/APCI mass spectra were recorded using an
Esquire 3000 ion trap mass spectrometer (Bruker Daltonik GmbH,
Bremen, Germany) equipped with a standard ESI/APCI source. The
numbering scheme for NMR assignments (Scheme 7) is based on
IUPAC guidelines.
9
8
1
9a
4a
8a
2
3
Figure 6 Molecular structure of 16a in the crystalline state. Displace-
ment ellipsoids are drawn at the 50% probability level, hydrogen atoms
are omitted for clarity. Selected bond lengths (Å) and angles: C(1)–C(2)
1.390(4), C(1)–C(14) 1.411(5), C(1)–C(15) 1.442(4), C(2)–C(3)
1.523(4), C(2)–C(11) 1.407(4), C(3)–C(58) 1.533(4), C(10)–C(11)
1.533(4), C(10)–C(25) 1.465(4), C(15)–C(16) 1.209(5), C(16)–Si(1)
1.845(3), C(17)–Si(1) 1.855(4), C(25)–C(26) 1.197(4), C(26)–C(27)
1.467(4), C(27)–C(28) 1.523(4), C(33)–C(34) 1.438(4), C(33)–C(46)
1.368(5), C(33)–C(47) 1.447(4), C(34)–C(35) 1.390(4), C(34)–C(43)
1.442(4), C(42)–C(43) 1.407(4), C(42)–C(57) 1.489(4), C(47)–C(48)
1.205(5), C(48)–Si(3) 1.848(3), C(49)–Si(3) 1.850(4), C(57)–C(58)
1.336(4), C(58)–C(59) 1.503(4), C(59)–C(60) 1.525(4); C(1)–C(2)–C(3)
127.3(3)°, C(1)–C(2)–C(11) 120.1(3)°, C(1)–C(15)–C(16) 174.3(3)°,
C(2)–C(1)–C(15) 123.0(3)°, C(2)–C(3)–C(4) 106.1(2)°, C(2)–C(3)–C(58)
106.2(2)°, C(3)–C(58)–C(57) 113.8(3)°, C(3)–C(58)–C(59) 119.4(3)°,
C(9)–C(10)–C(11) 104.6(2)°, C(9)–C(10)–C(25) 112.3(3)°, C(10)–
C(25)–C(26) 175.4(3)°, C(10)–C(57)–C(58) 113.9(3)°, C(15)–C(16)–
Si(1) 171.9(1)°, C(16)–Si(1)–C(17) 107.7(2)°, C(25)–C(26)–C(27)
178.4(4)°, C(26)–C(27)–C(28) 114.3(3)°, C(27)–C(28)–C(29) 115.5(3)°,
C(33)–C(34)–C(35) 122.6(3)°, C(33)–C(34)–C(43) 118.1(3)°, C(33)–
C(47)–C(48) 173.3(3)°, C(34)–C(33)–C(47) 120.2(3)°, C(34)–C(35)–
C(36) 122.0(3)°, C(42)–C(57)–C(58) 124.7(3)°, C(57)–C(58)–C(59)
126.7(3)°, C(58)–C(59)–C(60) 112.6(3)°, C(59)–C(60)–C(61) 112.9(3)°.
7
6
10a
10
4
5
Scheme 7 Anthracene numbering scheme, exemplarily shown for a
1,8,10-substituted anthracene derivative.
1,8-Dichloro-10-(ethynyl)anthracene (4)
Dry THF (25 mL) was added to CeCl3 (2.11 g, 8.6 mmol) at 0 °C under
vigorous stirring and the grey suspension was stirred for a further 3.5
h at r.t. A 0.5 M soln of ethynylmagnesium bromide in THF (17.0 mL,
8.5 mmol) was added dropwise at 0 °C, then a solution of 1,8-dichlo-
roanthracen-10(9H)-one (1.50 g, 5.7 mmol) dissolved in dry THF (20
mL) was added to the black solution at the same temperature. The
mixture was stirred overnight and allowed to warm up to r.t. The
mixture was quenched with sat. aq NH4Cl soln (20 mL) and the aque-
ous layer was extracted with THF (4 × 50 mL). The combined organic
phases were washed with brine and dried (MgSO4). The solvent was
evaporated and the crude yellow brownish solid was purified by flash
column chromatography. (i.d. = 3 cm, length 5 cm, n-pentane) afford-
ing 4 as a yellow solid; yield: 1.01 g (65%).
1H NMR (500 MHz, CDCl3): δ = 9.35 (s, 1 H, H9), 8.53 (d, 3JH,H = 8.8 Hz,
2 H, H4/H5), 7.68 (d, 3JH,H = 7.2 Hz, 2 H, H2/H7), 7.53 (dd, 3JH,H = 7.2, 8.7
Hz, 2 H, H3/H6), 4.03 (s, 1 H, C≡CH).
13C{1H} NMR (125 MHz, CDCl3): δ = 134.3, 133.2, 129.1, 127.1 (C3/C6),
126.6 (C2/C7), 126.0 (C4/C5), 122.7 (C9), 120.9, 89.5 (C≡CH), 79.9
(C≡CH).
MS (EI, 70 eV): m/z = 270.0 [M]+, 235.0 [C16H8Cl]+, 200.0 [C16H8]+.
HRMS: m/z [M]+ calcd for C16H8Cl2: 270.00031; found: 269.99416.
bearing four chlorine substituents in a directed manner. A
1,8-diethynylanthracene bridging unit can be utilized to
build up rigid frameworks, whereby an octynyl moiety en-
hances the solubility of the whole system. A slight flexibili-
ty is provided by a four- or five-membered (sila)alkyl chain
connecting two 1,8-dichloro-10-ethynyl units.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–J

H
J.-H. Lamm et al.
Paper
Synthesis
Bis[(1,8-dichloroanthracen-10-yl)ethynyl]dimethylsilane (8)
Due to extreme low solubility, no 13C{1H} NMR spectrum could be re-
corded.
1,8-Dichloro-10-ethynylanthracene (4; 2.25 g, 8.3 mmol) was dis-
solved in dry THF (150 mL). A 1.6 M soln BuLi in n-hexane (5.2 mL,
8.3 mmol) was added dropwise at –78 °C and the resulting black
solution was stirred at this temperature for 1 h. After slow warming
to r.t., Me2SiCl2 (0.5 mL, 4.1 mmol) was added. The mixture was
stirred overnight and hydrolyzed with water (120 mL). The resulting
yellow solid was filtered with suction and the filtrate was extracted
with CH2Cl2 (3 × 30 mL). The combined organic phases were dried
(MgSO4). The solvent was evaporated and the crude yellow solid was
recrystallized (benzene) affording 8 as a yellow solid; yield: 1.79 g
(73%).
1H NMR (500 MHz, CDCl3): δ = 9.34 (s, 1 H, H9), 8.60 (d, 3JH,H = 8.7 Hz,
2 H, H4/H5), 7.67 (d, 3JH,H = 7.2 Hz, 2 H, H2/H7), 7.49 (dd, 3JH,H = 7.2, 8.7
Hz, 2 H, H3/H6), 0.81 (s, 3 H, CH3).
13C{1H} NMR (125 MHz, CDCl3): δ = 134.2, 133.2, 129.1, 127.3 (C3/C6),
126.6 (C2/C7), 126.1 (C4/C5), 122.9 (C9), 118.4 (C10), 103.8 (C≡CSi),
102.4 (C≡CSi), –0.9 (CH3).
MS (MALDI-TOF, positive ions, DHB): m/z = 667.0 [C42H21Cl4]+, 524.0
[C42H20]+.
HRMS (MALDI-TOF): m/z [M]+ calcd for C42H20Cl4: 664.03136; found:
664.03177.
1,2-Bis[(1,8-dichloroanthracen-10-yl)ethynyl]benzene (10)
Synthesis according to the general procedure using 1,2-diiodoben-
zene (0.27 g, 0.82 mmol), 1,8-dichloro-10-(ethynyl)anthracene (4;
0.46 g, 1.71 mmol), and i-Pr2NH (20 mL). After stirring overnight at
r.t., the reaction was quenched with aq NH4Cl soln. The solid was fil-
tered with suction and washed with water and cold n-pentane. Traces
of the monosubstituted byproduct 10a (analytical data see below)
were removed by sublimation (170 °C, 7 × 10−3 mbar) to give 10 as a
yellow-brownish solid; yield: 0.42 g (83%).
Compound 10
29Si{1H} NMR (99 MHz, CDCl3): δ = –38.5.
MS (EI, 70 eV): m/z = 596.0 [M]+, 270.0 [C16H7Cl2]+.
HRMS: m/z [M]+ calcd for C34H20Cl4Si: 596.00829; found: 596.00817.
1H NMR (500 MHz, CDCl3): δ = 9.30 (s, 2 H, H9), 8.59 (d, 3JH,H = 8.7 Hz,
4 H, H4/H5), 7.91 (m, 2 H, PhH), 7.54 (m, 2 H, PhH), 7.49 (d, 3JH,H = 7.1
Hz, 4 H, H2/H7), 6.88 (dd, 3JH,H = 7.2, 8.7 Hz, 4 H, H3/H6).
13C{1H} NMR (125 MHz, CDCl3): δ = 133.8, 132.9, 132.6, 129.1, 129.0,
126.8, 126.5, 126.3, 125.8, 122.3, 118.8, 100.6, 90.2.
1,4-Bis(1,8-dichloroanthracen-10-yl)buta-1,3-diyne (9)
MS (ESI, positive mode, CH2Cl2/MeOH, AgBF4): m/z = 639.4 [C38H18Cl4-
1,8-Dichloro-10-(ethynyl)anthracene (4; 130 mg, 0.48 mmol) was
Na]+, 581.3 [C38H18Cl3]+.
added to
a blue solution of Cu(OAc)2 (0.30 g, 1.6 mmol) in
=
614.2 [M]+, 472.2
Et2O/MeOH/pyridine (4:1:1; 30 mL) and heated to reflux for 2 h. A red
solid precipitated, and this was filtered off and washed with small
amounts of Et2O; yield: 119 mg (92%).
1H NMR (300 MHz, CDCl3): δ = 9.40 (s, 2 H, H9), 8.63 (d, 3JH,H = 9.1 Hz,
4 H, H4/H5), 7.73 (d, 3JH,H = 7.0 Hz, 4 H, H2/H7), 7.62 (dd, 3JH,H = 7.5, 8.4
Hz, 4 H, H3/H6).
MS (MALDI-TOF, positive ions, DHB): m/z
[C38H18]+.
HRMS (MALDI-TOF): m/z [M]+ calcd for C38H18Cl4: 614.01571; found:
614.01569.
Compound 10a
Due to extreme low solubility, no 13C{1H} NMR spectrum could be re-
corded.
1H NMR (300 MHz, CDCl3): δ = 9.34 (s, 1 H, H9), 8.78 (d, 3JH,H = 8.7 Hz,
2 H, H4/H5), 7.98 (d, 3JH,H = 8.0 Hz, 1 H, PhH), 7.79 (dd, 3JH,H = 1.4, 7.7
Hz, 1 H, PhH), 7.69 (d, 3JH,H = 7.2 Hz, 2 H, H2/H7), 7.55 (dd, 3JH,H = 7.3,
MS (EI, 70 eV): m/z = 540.0 [M]+, 504.0 [C32H14Cl3]+, 468.0 [C32H14Cl2]+,
3
432.0 [C32H14Cl]+, 396.0 [C32H14]+, 269.9 [C16H7Cl2]+.
8.6 Hz, 2 H, H3/H6), 7.45 (td, JH,H = 1.0, 7.6 Hz, 1 H, PhH), 7.12 (td,
3JH,H = 1.6, 7.9 Hz, 1 H, PhH).
MS (MALDI-TOF, positive ions, DHB): m/z = 541.0 [C32H15Cl4]+, 468.5
[C32H14Cl2]+.
MS (EI, 70 eV): m/z = 471.7 [M]+, 436.8 [C22H11ClI]+, 343.8 [C22H11Cl2]+,
309.9 [C22H11Cl]+, 274.1 [C22H11]+.
HRMS (MALDI-TOF): m/z [M]+ calcd for C32H14Cl4: 537.98441; found:
537.98453.
1,2-Bis[(1,8-dichloroanthracen-10-yl)ethynyl]-4,5-dihexylben-
zene (11)
Sonogashira–Hagihara Coupling Reactions; General Procedure
Synthesis according to the general procedure using 1,2-dihexyl-4,5-
diiodobenzene (55 mg, 0.11 mmol), 1,8-dichloro-10-(ethynyl)anthra-
cene (4; 65 mg, 0.24 mmol), and i-Pr2NH (10 mL). After stirring over-
night at r.t., the reaction was quenched with aq NH4Cl soln. The aque-
ous layer was extracted with CH2Cl2 (3 × 15 mL), the combined organ-
ic phases were washed with brine and dried (MgSO4). The solvent
was evaporated and the crude yellow-orange solid was purified by
column chromatography (i.d. = 3 cm, length = 20 cm, n-pentane) to
give 11 and 11a as bright yellow solids; yield: 52 mg (60%).
The aryl halide and the (di-)ethynyl compound were dissolved in i-
Pr2NH and the solution was degassed by at least two freeze-pump-
thaw cycles. CuI and PdCl2(PPh3)2 (one spatula tip of each compound)
were added to the mixture which was then stirred under various con-
ditions (see below).
1,8-Bis[(1,8-dichloroanthracen-10-yl)ethynyl]naphthalene (7)
Synthesis according to the general procedure using 1,8-diiodonaph-
thalene (70 mg, 0.19 mmol), 1,8-dichloro-10-(ethynyl)anthracene (4;
100 mg, 0.37 mmol), and i-Pr2NH (10 mL). After stirring overnight at
r.t., the reaction was quenched with aq NH4Cl soln. The solid was fil-
tered with suction and washed with water and cold n-pentane to give
7 as a yellow-brownish solid; yield: 80 mg (63%).
1H NMR (300 MHz, CDCl3): δ = 9.33 (s, 2 H, H9), 8.78 (d, 3JH,H = 8.3 Hz,
4 H, H4/H5), 8.33 (m, 2 H, NaphH), 8.16 (m, 2 H, NaphH), 7.92 (d,
3JH,H = 6.9 Hz, 4 H, H2/H7), 7.69 (m, 4 H, H3/H6) 7.54 (m, 2 H, NaphH).
Compound 11
1H NMR (500 MHz, CDCl3): δ = 9.27 (s, 2 H, H9), 8.60 (d, 3JH,H = 8.7 Hz,
4 H, H4/H5), 7.66 (s, 2 H, PhH), 7.47 (d, 3JH,H = 7.1 Hz, 4 H, H2/H7), 6.87
(dd, 3JH,H = 7.3, 8.7 Hz, 4 H, H3/H6), 2.74 {m, 4 H, [PhCH2(C5H11)]2}, 1.70
{m, 4 H, [PhCH2CH2(C4H9)]2}, 1.42 {m, 12 H, [Ph(CH2)2(C3H6)CH3]2}, 0.94
{m, 6 H, [Ph(C5H10)CH3]2}.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–J

I
J.-H. Lamm et al.
Paper
Synthesis
13C{1H} NMR (125 MHz, CDCl3): δ = 142.5, 133.7, 133.1, 132.9 (PhCH),
129.1, 126.6, 126.5, 123.0, 122.0 (C9), 119.2, 101.2, 89.1, 32.9
(PhCH2C5H11), 31.9, 31.3, 29.9, 22.8, 14.3 (CH3). One signal missing
due to overlap or line broadening. Owing to similar NMR shifts, no
further assignments were possible.
MS (MALDI-TOF, positive ions, DHB): m/z = 784.3 [C50H43Cl4]+.
HRMS (MALDI-TOF): m/z [M]+ calcd for C50H42Cl4: 782.20351; found:
1H NMR (500 MHz, CDCl3): δ = 9.15 (s, 2 H, H9), 8.41 (d, 3JH,H = 8.7 Hz,
4 H, H4/H5), 7.56 (d, 3JH,H = 7.1 Hz, 4 H, H2/H7), 7.32 (dd, 3JH,H = 7.2, 8.7
Hz, 4 H, H3/H6), 2.88–2.93 (m, 4 H, C≡C-CH2), 2.15–2.19 (m, 4 H,
C≡CCH2CH2).
13C{1H} NMR (125 MHz, CDCl3): δ = 133.6, 133.0, 129.0, 126.4 (C3/C6),
126.3 (C2/C7), 126.1 (C4/C5), 121.0 (C9), 120.0, 102.7 (Ar-C≡C), 77.6
(Ar-C≡C), 28.4 (C≡CCH2CH2), 20.0 (C≡CCH2).
782.20291.
MS (EI, 70 eV): m/z = 596.4 [M]+, 559.1 [C36H22Cl3]+.
HRMS (MALDI-TOF): m/z [M]+ calcd for C36H22Cl4: 594.0476; found:
594.0493.
Compound 11a
1H NMR (500 MHz, CDCl3): δ = 9.31 (s, 1 H, H9), 8.79 (d, 3JH,H = 8.6 Hz,
2 H, H4/H5), 7.72 (s, 1 H, PhH), 7.68 (d, 3JH,H = 7.1 Hz, 2 H, H2/H7), 7.55
1,8-Bis[(1,8-dichloroanthracen-10-yl)ethynyl]-10-(oct-1-ynyl)an-
thracene (14)
3
(dd, JH,H = 7.4, 8.5 Hz, 2 H, H3/H6), 7.52 (s, 1 H, PhH), 2.61 {m, 4 H,
[PhCH2(C5H11)]2}, 1.61 {m, 4 H, [PhCH2CH2(C4H9)]2}, 1.39 {m, 12 H,
[Ph(CH2)2(C3H6)CH3]2}, 0.92 {m, 6 H, [Ph(C5H10)CH3]2}.
13C{1H} NMR (125 MHz, CDCl3): δ = 144.1, 141.3, 139.5, 133.9, 133.9,
133.1, 129.3, 127.1, 126.9, 126.7, 126.6, 122.1, 119.3, 103.7, 97.1, 88.3,
32.5, 32.5, 31.9, 31.8, 31.3, 31.2, 29.5, 29.5, 22.8, 22.8, 14.3. One signal
missing due to overlap or line broadening.
Synthesis according to the general procedure using 1,8-diethynyl-10-
(oct-1-ynyl)anthracene (17; 0.69 mg, 0.21 mmol), 10-bromo-1,8-di-
chloroanthracene (6; 170 mg, 0.52 mmol), and i-Pr2NH (43 mL). After
the mixture was heated to reflux for 5 d, the reaction was quenched
with aq NH4Cl soln. The aqueous layer was extracted with CH2Cl2 (2 ×
50 mL), the combined organic phases were washed with brine and
dried (MgSO4). The solvent was evaporated and the crude yellow solid
was purified by column chromatography (i.d. = 6 cm, length = 13 cm,
n-pentane/CH2Cl2, 8:1 ) and recrystallization (boiling toluene, 20 mL)
to give 14 as a barely soluble yellow solid; yield: 34 mg (20%).
MS (EI, 70 eV): m/z = 640.1 [M]+, 514.2 [C34H35Cl2]+, 498.9 [C33H32Cl2].
HRMS (EI): m/z [M]+ calcd for C34H35Cl2I: 640.11550; found:
640.11565.
1H NMR (500 MHz, CDCl3): δ = 10.16 [s, 1 H, H9 (bAnt)], 9.00 [s, 2 H,
1,3-Bis{[(1,8-dichloroanthracen-10-yl)ethynyl]dimethylsilyl}pro-
pane (12)
3
3
H9 (tAnt)], 8.70 [d, JH,H = 8.7 Hz, 2 H, H4/H5 (bAnt)], 8.38 [dd, JH,H
=
3
2.7, 7.1 Hz, 4 H, H2/H7 (tAnt)], 8.00 [(d, JH,H = 6.8 Hz, 2 H, H2/H7
(bAnt)], 7.67 [dd, 3JH,H = 6.8, 8.8 Hz, 2 H, H3/H6 (bAnt)], 6.99–7.05 [m, 8
H, H4/H5 and H3/H6 (tAnt)], 2.83 (t, 3JH,H = 7.1 Hz, 2 H, C≡CCH2), 1.89
(quint., 3JH,H = 7.3 Hz, 2 H, C≡CCH2CH2), 1.69 (quint., 3JH,H = 7.4 Hz, 2 H,
C≡CCH2CH2CH2), 1.43–1.47 (m, 4 H, CH2CH2CH3), 0.98 (t, 3JH,H = 6.8 Hz,
3 H, CH3); bAnt = bridging-Ant, tAnt = terminal-Ant.
Synthesis according to the general procedure using 1,3-bis(ethynyldi-
methylsilyl)propane (104 mg, 0.50 mmol), 10-bromo-1,8-dichloroan-
thracene (6; 326 mg, 1.00 mmol), and i-Pr2NH (30 mL). After the mix-
ture was heated to reflux for 4 d, the reaction was quenched with aq
NH4Cl soln (100 mL). The aqueous layer was extracted with CH2Cl2
(3 × 50 mL), the combined organic phases were washed with brine
and dried (MgSO4). The solvent was evaporated and the crude yellow
solid was purified by column chromatography (i.d. = 6 cm, length = 14
cm, n-pentane) to give 12 as a yellow solid; yield: 0.17 g (48%).
13C{1H} NMR (125 MHz, CDCl3): δ = 133.1, 132.9, 132.8, 131.8, 130.6
[C2/C7 (bAnt)], 128.5, 128.4, 126.3 [C3/C6 (bAnt)], 126.3, 125.7, 125.6,
124.5 [C9 (bAnt)], 122.1, 121.8 [C9 (tAnt)], 118.3, 103.8, 99.3 [bAnt-
C≡C-tAnt], 92.1, 31.6 (CH2CH2CH3 or CH2CH2CH3), 29.2 (C≡CCH2CH2 or
C≡CCH2CH2CH2), 29.1 (C≡CCH2CH2CH2 or C≡CCH2CH2), 22.8
(CH2CH2CH3 or CH2CH2CH3), 20.4 (C≡CCH2), 14.3 (CH3). Due to low sol-
ubility, no further 13C{1H} NMR signals were detected.
1H NMR (500 MHz, CDCl3): δ = 8.93 (s, 2 H, H9), 8.20 (d, 3JH,H = 8.7 Hz,
3
3
4 H, H4/H5), 7.37 (d, JH,H = 7.2 Hz, 4 H, H2/H7), 7.23 (dd, JH,H = 7.2,
8.7 Hz, 4 H, H3/H6), 2.01–2.09 (m, 2 H, SiCH2CH2), 1.04–1.10 (m, 4 H,
SiCH2), 0.41 (s, 12 H, CH3).
MS (MALDI-TOF, positive ions, DCTB): m/z = 824.1 [M]+.
HRMS (MALDI-TOF): m/z [M]+ calcd for C54H34Cl4: 822.1415; found:
13C{1H} NMR (125 MHz, CDCl3): δ = 133.4, 132.8, 128.4, 126.5 (C2/C7),
126.1 (C3/C6), 125.8 (C4/C5), 121.7 (C9), 118.5, 106.6 (Ar-C≡C), 101.7
(Ar-C≡C), 20.5 (Si-CH2), 19.5 (Si-CH2-CH2), –1.1 (CH3).
822.1431.
29Si{1H} NMR (99 MHz, CDCl3): δ = –15.3.
MS (EI, 70 eV): m/z = 698.1 [M]+.
HRMS (MALDI-TOF): m/z [M]+ calcd for C39H32Cl4Si2: 696.0797; found:
Crystal Structure Determination
Suitable crystals of compounds 8, 10a, 11, 11a, 12, 13, 15, 16, 16a,
and 17 were obtained by slow evaporation of saturated solutions in
CHCl3 (10a, 15, 16, 16a, and 17), n-pentane (11 and 11a), and benzene
(8, 12, and 13), respectively. Crystals were selected, coated with para-
tone-N oil, mounted on a glass fiber and transferred onto the goniom-
eter of the diffractometer into a nitrogen cold stream of 100 K solidi-
fying the oil.
696.0798.
1,8-Bis(1,8-dichloroanthracen-10-yl)octa-1,7-diyne (13)
Synthesis according to the general procedure using octa-1,7-diyne
(0.07 mL, 0.5 mmol), 10-bromo-1,8-dichloroanthracene (6; 349 mg,
1.07 mmol), and i-Pr2NH (13 mL). After stirring overnight at r.t., the
reaction was quenched with aq NH4Cl soln. The aqueous layer was ex-
tracted with CH2Cl2 (3 × 40 mL); the combined organic phases were
washed with brine and dried (MgSO4). The solvent was evaporated
and the crude yellow solid was purified by column chromatography
(i.d. = 3 cm, length = 15 cm, n-pentane/CH2Cl2, 1:1) to give 13 as a yel-
low solid; yield: 0.22 g (72%).
The structures were solved by direct methods and refined by full-ma-
trix least-squares cycles (program SHELX-97).24 Crystal and refine-
ment details, as well as CCDC numbers are provided in Table S1 in the
Supporting Information.25
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–J

J
J.-H. Lamm et al.
Paper
Synthesis
Funding Information
(7) See, for example: (a) Zhou, Q.; Swager, T. M. J. Am. Chem. Soc.
1995, 117, 12593. (b) Yang, J.-S.; Swager, T. M. J. Am. Chem. Soc.
1998, 120, 11864.
(8) See, for example: (a) Montali, A.; Smith, P.; Weder, C. Synth. Met.
1998, 97, 123. (b) Pang, Y.; Li, J.; Hu, B.; Karasz, F. E. Macromole-
cules 1998, 31, 6730. (c) Häger, H.; Heitz, W. Macromol. Chem.
Phys. 1998, 199, 1821.
This work was financially supported by Deutsche Forschungsgemein-
schaft (DFG). Grant Number MI 477/25-1.
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Acknowledgment
(9) See, for example: (a) Chmiel, J.; Neumann, B.; Stammler, H.-G.;
Mitzel, N. W. Chem. Eur. J. 2010, 16, 11906. (b) Lamm, J.-H.;
Horstmann, J.; Nissen, J. H.; Weddeling, J.-H.; Neumann, B.;
Stammler, H.-G.; Mitzel, N. W. Eur. J. Inorg. Chem. 2014, 4294.
(c) Katz, H. E. J. Org. Chem. 1989, 54, 2179.
The authors thank Sonja Fürst and Lisa Kuhlmann, M.Sc., for their as-
sistance in the lab, Klaus-Peter Mester and Gerd Lipinski for recording
NMR spectra, as well as Heinz-Werner Patruck for measuring mass
spectra.
(10) Lamm, J.-H.; Niermeier, P.; Mix, A.; Chmiel, J.; Neumann, B.;
Stammler, H.-G.; Mitzel, N. W. Angew. Chem. Int. Ed. 2014, 53,
7938; Angew. Chem. 2014, 126, 8072.
Supporting Information
(11) Chmiel, J.; Heesemann, I.; Mix, A.; Neumann, B.; Stammler, H.-
G.; Mitzel, N. W. Eur. J. Org. Chem. 2010, 3897.
(12) Lamm, J.-H.; Glatthor, J.; Weddeling, J.-H.; Mix, A.; Chmiel, J.;
Neumann, B.; Stammler, H.-G.; Mitzel, N. W. Org. Biomol. Chem.
2014, 12, 7355.
(13) Lamm, J.-H.; Vishnevskiy, Yu. V.; Ziemann, E.; Kinder, T. A.;
Neumann, B.; Stammler, H.-G.; Mitzel, N. W. Eur. J. Inorg. Chem.
2014, 941.
(14) Chmiel, J. Dissertation; University of Münster: Germany, 2010.
(15) Imamoto, T.; Takiyama, N.; Nakamura, K.; Hatajima, T.; Kamiya,
Y. J. Am. Chem. Soc. 1989, 111, 4392.
Supporting information for this article is available online at
https://doi.org/10.1055/s-0036-1591925.
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© Georg Thieme Verlag Stuttgart · New York — Synthesis 2018, 50, A–J