Donor-substituted perethynylated dehydroannulenes and radiaannulenes: Acetylenic carbon sheets featuring intense intramolecular charge transfer

Article abstract of DOI:10.1002/hlca.200490104

In this article, we report the preparation of unprecedented φ-conjugated macrocycles (Fig. 1) by acetylenic scaffolding using modular tetraethynylethene (TEE, 3,4-diethynylhex-3-ene-1,5-diyne) building blocks. A novel photochemical access to (Z)-bisdeprot

Full text of DOI:10.1002/hlca.200490104

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Donor-Substituted Perethynylated Dehydroannulenes and Radiaannulenes:
Acetylenic Carbon Sheets Featuring Intense Intramolecular Charge Transfer
by Frieder Mitzela), Corinne Boudonb), Jean-Paul Gisselbrechtb), Paul Seilera), Maurice Grossb), and
FranÁois Diederich*a)
a) Laboratorium f¸r Organische Chemie, ETH-Hˆnggerberg, CH-8093Z¸rich
(e-mail: diederich@org.chem.ethz.ch)
) Laboratoire d×Electrochimie et de Chimie Physique du Corps Solide, UMR 7512, C.N.R.S., Universite Louis
b
¬
Pasteur, 4 rue Blaise Pascal, F-6700 Strasbourg
In this article, we report the preparation of unprecedented p-conjugated macrocycles (Fig. 1) by acetylenic
scaffolding using modular tetraethynylethene (TEE, 3,4-diethynylhex-3-ene-1,5-diyne) building blocks. A novel
photochemical access to (Z)-bisdeprotected TEEs (Scheme 1) enabled the synthesis of the anilino-substituted
perethynylated octadehydro[12]- (5) and dodecadehydro[18]annulenes (6) (Scheme 2). Following the
serendipitous discovery of perethynylated radiaannulenes (Scheme 3) that can be viewed as hybrids between
perethynylated dehydroannulenes and expanded radialenes, two series of monocyclic (7 9; Scheme 6) and
bicyclic (10 and 11; Scheme 7) representatives were prepared. Substantial strain in the macrocyclic perimeter of
radiaannulene 7 was revealed by X-ray crystal-structure analysis (Fig. 2). Nevertheless, mono- and bicyclic
radiaannulenes are stable at room temperature in air for months. The opto-electronic properties of both
dehydroannulenes and radiaannulenes are substantially enhanced by the introduction of the peripheral anilino
donor groups that undergo strong intramolecular charge-transfer interactions with the electron-accepting all-C
cores. As a result, the UV/VIS spectra feature intense, bathochromically shifted charge-transfer bands that
disappear upon protonation of the anilino moieties and are fully recovered upon neutralization (Figs. 4 9). A
comparison between anilino-substituted perethynylated dehydroannulenes, expanded radialenes, and radiaan-
nulenes revealed that the efficiency of the intramolecular charge-transfer interaction strongly depends on the
structure of the electron-accepting all-C perimeter. Electrochemical investigations (Table) demonstrated that
the radiaannulenes are particularly powerful electron acceptors. Thus, bicyclic radiaannulene 11, which
‡
possesses eight peripheral 3,5-di(tert-butyl)phenyl substituents, is reversibly reduced at À0.83V in THF ( vs. Fc /
Fc), making it a better electron acceptor than buckminsterfullerene C60 under comparable conditions.
1. Introduction. Decades after the seminal work by Sondheimer and co-workers
[1], dehydroannulenes [2 4] and other types of acetylenic macrocycles [5 14]
continue to attract extraordinary interest for various reasons. First, experimental and
theoretical studies on these p-electron systems continue to deepen the understanding
of the phenomenon of aromaticity [4f][15]. Second, many of these acetylenic
chromophores display fascinating opto-electronic properties [16] and third, it has been
noted that such C-rich molecules represent sub-structures of two-dimensional all-C
networks [17][18] and are potential precursors for the preparation of new molecular C
allotropes [3b][19].
In the early 1990s, we started a program on macrocyclic acetylenic scaffolding by
using a versatile new family of tetraethynylethene (TEE, 3,4-diethynylhex-3-ene-1,5-
diyne) building blocks [20]. We prepared per(silylethynylated) octadehydro[12]annu-
lene 1 and dodecadehydro[18]annulene 2, and demonstrated that the former has
antiaromatic character, whereas the latter is aromatic [21] (Fig. 1). In another work, we
synthesized the first expanded radialenes such as 3 and 4, members of a new class of

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Fig. 1. Perethynylated dehydroannulenes, expanded radialenes, and radiaannulenes

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cross-conjugated macrocyclic p-chromophores [16][21b][22] (see also [5]). Both
perethynylated dehydroannulenes and expanded radialenes were shown by electro-
chemical investigations to be strong electron acceptors [23], which we explained with
the large number of C(sp)-atoms in the large all-C cores. Reduction of the expanded
radialenes was found to be particularly facilitated [16b], and this was recently
explained by aromaticity enhancement at the stage of the formed mono- and di-anions
[24]. Introduction of peripheral N,N-dialkylanilino groups into 4 resulted in strong,
bathochromically shifted intramolecular charge-transfer transitions [16].
We subsequently became interested in functionalizing dehydroannulenes 1 and 2
with peripheral donor groups in order to investigate whether intramolecular charge-
transfer effects are influenced by the aromaticity/antiaromaticity of the macrocyclic
perimeters. However, (Z)-bisdeprotected TEEs, required for oxidative macrocycliza-
tion [25], had been available only by a tedious multistep synthesis including several
highly unstable intermediates, which prevented the preparation of functionalized
derivatives of 1 and 2. Here, we report a new, simple photochemical route to (Z)-
bisdeprotected TEEs that finally enabled the preparation and spectroscopic inves-
tigation of the perethynylated dehydroannulenes 5 and 6, which bear lateral N,N-
dimethylanilino (DMA) substituents (for a preliminary communication of parts of this
work, see [26]). We also report here the synthesis and properties of 7 9, and 10 and 11,
mono- and bicyclic members of a new family of all-C macrocycles, that, from a
structural viewpoint, can be regarded as hybrids between the dehydroannulenes and
expanded radialenes, and which we have, therefore, christened −radiaannulenes× (for a
preliminary communication, see [27]). The intramolecular charge-transfer properties
of the new donor-substituted all-C cores 5 11 are discussed in detail.
2. Results and Discussion. 2.1. Photochemical Synthesis of (Z)-Bisdeprotected
TEEs. Starting from the trans-bisdeprotected TEE 12 [20a], the trans-diarylated, trans-
disilylated TEEs 13a 13f (13a, 13b, and 13e had been previously reported; see [28])
were prepared in good yield by Pd0-catalyzed Sonogashira cross-coupling with the
corresponding aryl iodides 14a 14f (Scheme 1).
The compounds were subsequently examined for their ability to undergo photo-
chemical (E)/(Z) isomerization [29]. For this purpose, solutions of 13a 13f in Et2O
(c ˆ 2.5 mm) were irradiated with a water-cooled medium-pressure Hg lamp (125 W)
over the course of 2 5 h at room temperature. Doubling of the acetylenic 13C-NMR
resonances of the crude products, compared to the spectra of the starting materials,
suggested that photochemical (Z)/(E) isomerization had taken place in all runs
(Scheme 1). The isomeric mixtures 13a/15a and 13b/15b, respectively, could be readily
separated by flash chromatography (FC; SiO2; CH2Cl2/hexane mixtures) to yield ca.
40% of the desired (Z)-isomer along with ca. 50% of the (E)-isomer that was used for
further photoisomerization. (E)-Isomers 15a and 15b are air- and light-stable, yellow-
orange solids, but they isomerize rapidly in solution when exposed to light. In contrast,
the formed isomeric mixtures 13c/15c to 13f/15f could not be separated on a
preparative scale (FC); evidently the polarity of the respective (Z)- and (E)-
derivatives is too similar in these cases.
2.2. Synthesis of the DMA-Substituted Perethynylated Dehydroannulenes 5 and 6.
The (i-Pr)3Si protecting groups of 15a and 15b were readily cleaved with Bu4NF in

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Scheme 1. Synthesis of (E)-Diaryl-TEEs 13a 13f and Photochemical (E) ! (Z) Isomerization
a) [PdCl2(PPh3)2], CuI, (i-Pr)2NH (13a 13d, 13f) or Et3N (13e), r.t., 16 18 h; 85% (13a); 99% (13b); 78%
(13c); 76% (13d); 28% (13e); 72% (13f). b) hn, Et2O, r.t., 2 5 h; 41% (15a) and 53% (13a); 39% (15b) and
52% (13b); mixtures 13c/15c to 13f/15f not separable on a preparative scale.
moist THF, and the tetrabutylammonium salts subsequently removed by filtration
through as short plug of SiO2. The resulting free (Z)-enediynes can be handled without
problems in solution but deteriorate rapidly in neat form. Hence, they were not
characterized and were always freshly prepared before use in subsequent oxidative
couplings. Hay coupling of 15a afforded octadehydro[12]annulene 5 and dodecadehy-
dro[18]annulene 6 as deep-purple solids (Scheme 2). Interestingly, higher macrocyclic
oligomers were not detectable in the matrix-assisted laser-desorption-ionization
(MALDI-TOF) mass spectrum (matrix: DCTB ˆ {(2E)-3-[4-(tert-butyl)phenyl)-2-
methylprop-2-enylidene}malononitrile) of the crude product.
The two macrocycles are well soluble in CH2Cl2 and CHCl3 but only sparingly
soluble in many other organic solvents, which rendered their separation by repetitive
FC (3 Â SiO2; CH2Cl2/hexane/Et3N 1:1:0 ! 99 :0 :1) quite difficult. The ratio of the
two annulenes is concentration-dependent [21b], as was qualitatively assessed by TLC
(SiO2; CH2Cl2/hexane 1:1) of the crude reaction mixture. Nevertheless, even under
very high dilution conditions, which favor cyclodimerization over cyclotrimerization,
the isolated yield of octadehydro[12]annulene 5 always remained low as a result of its
marked instability, which caused a significant loss of product during workup and
purification. Careful removal of solvents after workup and chromatography was
mandatory; before full evaporation of the solvents, 5 was precipitated with hexane to
avoid complete decomposition. Once a solid, the compound could be stored for several
days at À208 without significant decomposition. Dodecadehydro[18]annulene 6, on the
other hand, is remarkably stable and can be handled without problem. The identity of
the two annulenes was confirmed by 1H- and 13C-NMR spectroscopy, and high-

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Scheme 2. Synthesis of Perethynylated Dehydroannulenes 5 and 6
a) Bu4NF, THF, 08, 10 min. b) CuCl, N,N,N',N'-Tetramethylethylenediamine (TMEDA), air, Me2CO, r.t., 2 h;
2% (5); 22% (6).
resolution MALDI Fourier-transform (FT) mass spectrometry. Attempts to prepare
the corresponding dehydroannulenes, which bear electron-withdrawing 4-nitrophenyl
groups, starting from 15b, remained unsuccessful. In all cases, complete decomposition
of the starting material was observed.
2.3. Synthesis of Monocyclic Perethynylated Radiaannulenes. The discovery of a new
class of p-chromophores, radiaannulenes 7 9, occurred during the attempted
formation of macrocycle 16 (Scheme 3). When trimeric TEE 17 was reacted under
oxidative Hay coupling conditions with 15a (4 equiv.), after in situ silyl deprotection of
the two compounds, the targeted new p-system 16 was not formed, but rather
radiaannulene 7 with a smaller, much more strained 16-membered macrocyclic
perimeter was obtained (MS, NMR). This observation led to the present systematic
investigation of the radiaannulenes.
In view of the solubility problems encountered with the DMA-substituted
dehydroannulenes 5 and 6, we decided to introduce peripheral anilino donors with
longer alkyl chains. For this purpose, the new TEE 18 with N,N-dihexylanilino groups
was prepared from 19 via 20 and 21, by using dibromoolefin 22 [20a] (Scheme 4).
TEEs 18, 23 [20a], and 24 [28] were subsequently mono-desilylated with K2CO3 in
MeOH/THF and combined with a solution of in situ bisdeprotected (Z)-enediynes 15a
and 15b, respectively, followed by addition of Hay catalyst (Scheme 5). The use of a six-
fold excess of 18, 23, or 24 ensured that only the desired mixed TEE trimers 17 and
25 27 were formed besides dimers resulting from homo-coupling of the mono-
deprotected TEEs.

Scheme 3. Attempted Synthesis of 16 and Unexpected Preparation of Radiaannulene 7
a) Bu4NF, THF. b) CuCl, TMEDA, air, Me2CO.

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Scheme 4. Synthesis of TEE 18
a) [PdCl2(PPh3)2)], CuI, (i-Pr)2NH, r.t., 5 h; 95%. b) K2CO3, MeOH, THF, r.t, 30 min; 99%. c)
[PdCl2(PPh3)2)], CuI, (i-Pr)2NH, r.t., 16 h; 69%.
The mixed TEE trimers and homo-dimer side products were readily separated by
FC (SiO2; hexane/AcOEt or hexane/CH2Cl2). The brown-colored trimers 17, 26, 27,
and purple-colored 25 are air-stable compounds that were fully characterized. After
desilylation with Bu4NF, they were subjected to ring closure under Hay coupling
conditions (Scheme 6). Starting from 17, 25, and 27, the perethynylated radiaannulenes
7 9 were isolated as the sole products after purification. They are remarkably stable,
brown (7) or waxy purple solids (8 and 9) that were fully characterized. In the
cyclization of 26, radiaannulene 28 was also formed, as detected by mass spectrometry,
but amounts of isolated, purified macrocycle were consistently too small for full
characterization. It thus appears that 28 is destabilized by the four electron-with-
drawing peripheral 4-nitrophenyl groups.
Single crystals of radiaannulene 7 were obtained by slow diffusion of hexane into a
≈
solution in CHCl3. The compound crystallizes in the triclinic space group P1 with two
molecules in the unit cell. The X-ray crystal structure [27] shows a virtually planar
macrocyclic framework with a mean out-of-plane deviation of 0.040 ä and a maximum
deviation of 0.091 ä (C(6); Fig. 2). The bond angles of the TEE moiety around the
C(1)ˆC(16) bond are all close to the ideal angle of 1208 (117.08 122.08). Strain in the
16-membered ring is expressed by bending of the three buta-1,3-diynediyl moieties,
with CꢀCÀC(sp) angles as low as 169.28 and by
a deviation of the
C(sp)ÀC(sp2)ÀC(sp) angles at the exocyclic ethylene units from ideally 1208 to ca.
1118. Most strain, however, occurs at the macrocyclic CꢀCÀC(sp2) angles
C(4)ÀC(5)ÀC(6), C(6)ÀC(7)ÀC(8), C(9)ÀC(10)ÀC(11), and C(11)ÀC(12)ÀC(13),
with a bending from ideally 1808 to ca. 1648.
2.4. Synthesis of Bicyclic Perethynylated Radiaannulenes. The synthesis of the
bicyclic radiaannulenes 10 and 11 started from the parent tetraethynylethene 29 that
was prepared in situ by treatment of the corresponding tetrakis(trimethylsilyl)-
protected derivative in MeOH/THF with K2CO3 [20a] (Scheme 7). Oxidative Hay
coupling of 29 with an excess of TEEs 18, 23, or 30 [16b], after removal of their Me3Si
protecting groups by protodesilylation, afforded the pentameric TEEs 31 33,
respectively, in fair yields (29 39%), together with considerable amounts of homo-
coupled TEE dimers. Pentamers 31 and 33 were readily separated from the homo-

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Scheme 5. Synthesis of TEE Hetero-Trimers 17 and 25 27
a) Bu4NF, THF, 08, 10 min. b) K2CO3, MeOH/THF, r.t., 2.5 h. c) CuCl, TMEDA, air, Me2CO, r.t., 1 2 h; 57%
(17); 32% (25); 63% (26); 32% (27).
dimers (formed from 23 and 30, resp.) by FC (SiO2; hexane/AcOEt 6 :1). Under these
conditions, pentamer 32 could not be separated from the undesired homo-dimer (of
18), but full separation was possible by gel-permeation chromatography (GPC) on a
polystyrene resin cross-linked with divinylbenzene (Bio-Beads 1-SX) with THF as the
eluent. The pentameric TEEs are air-stable, red (31 and 33) or brown (32) waxy solids
that were fully characterized. Compounds 31 33 represent the first derivatives of

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Scheme 6. Synthesis of Monocyclic Radiaannulenes
a) Bu4NF, THF, 08, 10 min. b) CuCl, TMEDA, air, Me2CO, r.t., 1 1.5 h; 48% (7); 32% (8); traces (28); 14%
(9).
tetrakis(buta-1,3-diynyl)ethane (C18H4; 5,6-di(buta-1,3-diynyl)dec-5-ene-1,3,7,9-tet-
rayne) that had so far been elusive [20a].
Initial attempts to prepare the bicyclic perethynylated radiaannulenes 10 and 34 by
silyl deprotection (Bu4NF) of the pentameric TEEs, followed by intramolecular
oxidative Hay coupling under conditions identical to those applied to the synthesis of
the monocyclic derivatives 7 9, failed. TLC Analysis indicated that the desilylation
proceeded smoothly, and that the deprotected pentamers were sufficiently stable for
further manipulation. Rather, complete decomposition occurred upon addition of the
Hay catalyst. Gratifyingly, a slight modification of the Hay coupling conditions, with
Me2CO/THF/PhH 1:1:1 instead of pure Me2CO as solvent allowed the preparation of
the octakis(N,N-dihexylanilino) derivative 10 that was isolated in 16% yield as a deep-
purple, waxy solid. On the other hand, the targeted octaphenyl derivative 34 could still
not be isolated, and only decomposition was observed. In sharp contrast, octakis[3,5-
di(tert-butyl)phenyl] derivative 11 was obtained in excellent yield (88%). Thus, our
investigations of perethynylated dehydroannulenes, expanded radialenes [16], and
radiaannulenes consistently show that electron-donating peripheral substituents such

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Fig. 2. ORTEP Plot of 7 with arbitrary numbering. The H-atoms are omitted for clarity. Atomic displacement
parameters at 183K are drawn at the 30% probability level. Selected bond lengths [ä] and bond angles [ 8]:
C(1)ÀC(2), 1.427(2); C(2)ÀC(3), 1.204(2); C(3)ÀC(4) 1.364(2); C(4)ÀC(5), 1.209(2); C(5)ÀC(6), 1.423(2);
C(6)ÀC(56), 1.378(2); C(6)ÀC(7), 1.423(2); C(7)ÀC(8), 1.206(2); C(8)ÀC(9), 1.358(2); C(9)ÀC(10),
1.207(2); C(10)ÀC(11), 1.425(2); C(11)ÀC(39), 1.374(2); C(11)ÀC(12), 1.424(2); C(12)ÀC(13), 1.207(2);
C(13)ÀC(14), 1.368(3); C(14)ÀC(15), 1.206(3); C(15)ÀC(16), 1.421(3); C(1)ÀC(16), 1.387(3);
C(19)ÀC(20), 1.396(3); C(19)ÀC(24), 1.398(2); C(20)ÀC(21), 1.373 (3); C(21)ÀC(22), 1.406(3);
C(22)ÀC(23), 1.401(3); C(23) ÀC(24), 1.373(3); C(30)ÀC(31), 1.390(3); C(30)ÀC(35), 1.397(3);
C(31)ÀC(32), 1.381(3); C(32)ÀC(33), 1.403(3); C(33)ÀC(34), 1.402(3); C(34)ÀC(35), 1.371(3);
C(16)ÀC(1)ÀC(2),
C(3)ÀC(4)ÀC(5),
C(6)ÀC(7)ÀC(8),
120.17(16);
175.98(19);
164.86(18);
C(1)ÀC(2)ÀC(3),
C(4)ÀC(5)ÀC(6),
C(7)ÀC(8)ÀC(9),
178.64(19);
163.18(18);
169.17(19);
C(2)ÀC(3)ÀC(4),
C(5)ÀC(6)ÀC(7),
C(8)ÀC(9)ÀC(10),
174.50(19);
111.76(14);
170.12(19);
C(9)ÀC(10)ÀC(11), 163.88(19); C(10)ÀC(11)ÀC(12), 111.18(15); C(11)ÀC(12)ÀC(13), 162.78(17);
C(12)ÀC(13)ÀC(14), 176.55(18); C(13)ÀC(14)ÀC(15), 174.56(19); C(14)ÀC(15)ÀC(16), 178.80 (20);
C(15)ÀC(16)ÀC(1), 120.99(15).
as dialkylanilino or 3,5-di(tert-butyl)phenyl groups provide substantial stabilization to
the extended electron-deficient macrocyclic all-C cores. In addition to electronic
effects, steric protection may also add to the observed kinetic stability. It should be
mentioned that all mono- and bicyclic radiaannulenes isolated in this work are stable at
room temperature in the air for months.

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Scheme 7. Synthesis of Bicyclic Radiaannulenes
a) K2CO3, MeOH, THF, r.t. 15 30 min. b) CuCl, TMEDA, air, Me2CO, r.t., 1.5 2.5 h; 39% (31, 32); 29% (33).
c) Bu4NF, THF, 08, 10 min. d) CuCl, TMEDA, air, Me2CO/THF/PhH 1 :1:1, r.t., 1 2 h; 0% (34); 16% (10);
88% (11).

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1
The proposed structures of 10 and 11 were confirmed by IR, UV/VIS, H- and
13C-NMR spectroscopy, and MALDI-TOF mass spectrometry. A high-resolution FT-
‡
ICR (ion-cyclotron-resonance) mass spectrum of 11 (matrix: DCTB) features the M
ion (m/z 2113.3166; calc. for C162H168: 2113.3146) as the only significant peak (Fig. 3).
The 13C-NMR spectrum (125 MHz) of 11 in CDCl3 displays the expected 21 resonances
in the C(sp)/C(sp2) spectral region, thereby confirming the high symmetry (D2h) of the
bicyclic structure.
Fig. 3. High-resolution FT-ICR-MALDI mass spectrum (positive-ion mode) of 11. Matrix: DCTB.
2.5. UV/VIS Spectroscopy. We were interested in exploring whether the aromaticity/
antiaromaticity of the new perethynylated dehydroannulenes would affect their
capacity to mediate p-electron donor-acceptor conjugation. The UV/VIS spectrum of
the aromatic dehydro[18]annulene 6 in CHCl3 (Fig. 4) is dominated by an intense,
broad longest-wavelength absorption band at lmax ˆ 518 nm (2.39 eV, e ˆ 105200 mÀ1
cmÀ1) and features an end-absorption (around 700 nm, 1.77 eV) that is bathochromi-
cally shifted by more than 200 nm compared to that of the corresponding silyl-
substituted derivative 2 (480 nm, 2.57 eV) [21]. Upon acidification with TsOH, the
color of the solution of 6 changes from purple to yellow, which is the color of the silyl-
substituted derivative 2. Accordingly, the intense absorption at 518 nm disappears
nearly completely, and the spectrum becomes strikingly similar to that of 2 with the
most-intense band now being shifted to 427 nm (2.90 eV; 2: 405 nm, 3.06 eV). The
residual absorptivity above 500 nm in the acidified solution may be explained by
incomplete hexaprotonation. Neutralization with Et3N completely regenerates the
original spectrum. This behavior identifies the intense longest-wavelength absorption
at lmax ˆ 518 nm as a charge-transfer band, resulting from efficient intramolecular
charge-transfer between the electron-donating anilino groups and the electron-
accepting all-C core.

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Fig. 4. UV/VIS Spectra of 5 and 6 in pure CHCl3 (thick lines) and after acidification with TsOH (thin lines)
In agreement with its antiaromaticity, the per(silylethynylated) dehydro[12]annu-
lene 1 featured a much lower HOMO-LUMO gap (end-absorption near 660 nm,
1.87 eV) than the corresponding aromatic dehydro[18]annulene 2 (480 nm, 2.57 eV),
with weak bands between 490 and 620 nm (e ˆ 200 to 400 mÀ1 cmÀ1) being responsible
for its buckminsterfullerene-type magenta-purple color [21]. In the donor-substituted
antiaromatic dehydro[12]annulene 5, these weak bands are now completely overlapped
by an intramolecular charge-transfer transition, featuring the same absorption
maximum (lmax ˆ 518 nm, 2.39 eV, e ˆ 35100 mÀ1 cmÀ1) and end-absorption (around
700 nm, 1.77 eV) as the aromatic dehydro[18]annulene 6 (Fig. 4). As in the case of 6,
the lowest-energy band disappears nearly completely upon acidification with TsOH
and is regenerated upon neutralization with Et3N. Clearly, both [12]annulene 5 and
[18]annulene 6 are capable of mediating p-electron donor-acceptor conjugation in a
similar fashion. Interestingly, the intensity of the charge-transfer band of 5 is
significantly weaker than that of 6, even when the smaller number of donor-acceptor
conjugation paths is taken into account1). This is somewhat surprising since one might
expect the charge-transfer to be more efficient in the [12]annulene, as the uptake of
electrons reduces the antiaromaticity, whereas, in the case of the [18]annulene, the
uptake of electrons is accompanied by a loss of aromaticity. Theoretical calculations
might provide further insight into the additional factors that govern the intensity of
these electronic transitions.
1
)
To rule out the possibility that the molar extinction coefficient of 5 is so much lower than that of 6 due to
decomposition during the UV/VIS measurements, the homogeneity of
5 was checked after the
measurements by 1H-NMR spectroscopy and MALDI-TOF-MS. No indications for any decomposition
were obtained.

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The anilino-substituted monocyclic perethynylated radiaannulenes 7 9 also dis-
play intense intramolecular charge-transfer bands in CHCl3 (Fig. 5). Upon acid-
ification with CF3COOH (TFA), these bands disappear, and, not surprisingly, similar
UV/VIS spectra are obtained for the three protonated compounds. The residual
absorptivity above 550 nm in the case of the hexaanilino derivative 8 may be explained
by incomplete hexaprotonation. Upon neutralization with Et3N, the original spectra are
all regenerated.
Fig. 5. UV/VIS Spectra of 7 (top left), 8 (top right), and 9 (bottom left) in pure CHCl3 (thick lines) and after
addition of TsOH (thin lines). Shown on the bottom right is a comparison of the spectra of 7 9 in CHCl3.
Position and intensity of the CT band are affected by the number of peripheral
donor groups. Thus, the CT band of dianilino-substituted 7 is rather weak (lmax
ˆ
588 nm (2.11 eV, e ˆ 31900 mÀ1 cmÀ1)) and detectable only as a shoulder. In contrast,
hexaanilino-substituted 8 features a split CT band (lmax ˆ 521 nm (2.37 eV, e ˆ
106100 mÀ1 cmÀ1) and lmax ˆ 615 nm (2.02 eV, e ˆ 99900 mÀ1 cmÀ1)), that is much more

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intense and bathochromically shifted. The end-absorptions of both compounds,
however, are nearly identical (around 700 nm, 1.77 eV).
Introducing two 4-nitrophenyl donor groups in 9, while maintaining four peripheral
anilino donor groups, does not affect the position of the longest-wavelength maximum
of the split CT band (lmax ˆ 614 nm (2.02 eV, e ˆ 89300 mÀ1 cmÀ1) as compared with
hexa-donor-substituted 8 (lmax ˆ 615 nm (2.02 eV, e ˆ 99900 mÀ1 cmÀ1). UV/VIS
Measurements of acyclic TEE dimers with anilino donor substituents had already
previously shown that the strong electron-acceptor properties of the all-C cores are
only weakly enhanced upon further introduction of additional 4-nitrophenyl acceptor
groups [16b]. The end-absorption, however, shifts substantially from ca. 700 nm
(1.77 eV) in 8 to ca. 800 nm (1.55 eV) in 9.
The intramolecular charge-transfer between the electron-donating amino groups
and the electron-accepting all-C core in 7 can be further assessed by determining the
quinoid character of the anilino ring. The quinoid character of a benzene ring is
expressed by the parameter drˆ [(a À b) ‡ (c À b)]/2, with a, b, and c being the
different bond lengths in the ring as shown in Fig. 6 [30]. In benzene, dr equals zero,
whereas values between 0.08 and 0.1 are found for fully quinoid rings. With the bond
lengths from the X-ray crystal-structure analysis (Fig. 2), an average value drˆ 0.0245
is calculated for the two anilino groups of 7, indicating considerable quinoid character
of the rings and confirming the prevalence of intramolecular charge-transfer (for an
even more pronounced quinoid character, see [31]).
Fig. 6. Resonance structures of donor-acceptor-substituted benzene rings. The quinoid character of the benzene
ring is a measure of the strength of the intramolecular charge transfer.
A comparison of the UV/VIS spectra of acyclic TEE trimer 25 and radiaannulene 8
reveals that the intramolecular charge-transfer interactions are much more efficient in
the macrocyclic compound (Fig. 7). Whereas the lowest-energy band with CT
character in acyclic 25 appears at lmax ˆ 486 nm (2.56 eV, e ˆ 98800 mÀ1 cmÀ1), the
split CT band in macrocyclic 8 is strongly bathochromically shifted (lmax ˆ 521 nm
(2.37 eV, e ˆ 106000 mÀ1 cmÀ1) and lmax ˆ 615 nm (2.02 eV, e ˆ 99900 mÀ1 cmÀ1)). On the
other hand, the longest linear p-conjugation pathways in both compounds are identical,
and the optical end-absorptions occur at similar wavelengths (around 700 nm, 1.77 eV).
Hence, the fact that the acetylenic core of 8 is a better electron acceptor is a special
feature of the macrocyclic scaffold. A similar effect was also observed for the anilino-
substituted expanded radialene 4, which displays a pronounced macrocyclic p-
conjugation effect when compared with acyclic TEE dimers possessing the same
longest linear p-conjugation pathway [16b].

Helvetica Chimica Acta Vol. 87 (2004)
1145
Fig. 7. UV/VIS Spectra of acyclic TEE trimer 25 and radiaannulene 8 in CHCl3
Dehydroannulene 6, expanded radialene 4, and radiaannulene 8 all are macrocyclic
TEE trimers with the same number of peripheral anilino donor groups. Nonetheless,
their UV/VIS spectra display profound differences (Fig. 8). The longest-wavelength
charge-transfer absorption shifts bathochromically from 518 nm (e ˆ 105200 mÀ1 cmÀ1)
in 6 (with a shoulder at 533 nm) to 615 nm (e ˆ 99900 mÀ1 cmÀ1) in 8, and to 646 nm
(e ˆ 171000 mÀ1 cmÀ1) [16b] in 4, while at the same time, the optical end-absorption also
shifts from around 700 nm (in 6 and 8) to ca. 750 nm (in 4). Furthermore, the
exceptionally high molar extinction coefficient of 4, when compared with 6 and 8, is
noteworthy. Clearly, the capability of macrocyclic TEE scaffolds to mediate charge-
transfer interactions depends much on the arrangement of the TEE moieties in the
macrocyclic all-carbon perimeter2). Future theoretical studies should provide more
insight into the observed dependency of intramolecular donor-acceptor interactions
from the structure of the macrocyclic acceptor.
Bicyclic radiaannulene 10 with its electron-accepting C50 core features the most-
intense and the most bathochromically shifted charge-transfer absorptions of all
macrocyclic TEE derivatives prepared so far. Its UV/VIS spectrum displays two intense
maxima at lmax ˆ 558 nm (2.22 eV, e ˆ 176700 mÀ1 cmÀ1) and lmax ˆ 698 nm (1.78 eV,
e ˆ 85900 mÀ1 cmÀ1; Fig. 9). The end-absorption reaches 850 nm (1.46 eV), which is the
lowest-energy one known for TEE oligomers. Even expanded [5]- and [6]radialenes
with C50 and C60 cores and ten or twelve peripheral anilino groups, respectively, do not
2
)
It is known that the elongation of the alkyl chains in N,N-dialkylanilines can enhance their electron-
donating ability [32]. However, we believe that the spectral differences between short-chain 6, and longer-
chain 4 and 8 cannot be explained by such chain-length effects. The CT band maxima are not simply
shifted but, instead, entirely new absorption bands appear in the spectra of 4 and 8.

1146
Helvetica Chimica Acta Vol. 87 (2004)
Fig. 8. Comparison of the UV/VIS spectra of hexaanilino-substituted dehydroannulene 6, expanded radialene 4,
and radiaannulene 8
feature such low-energy CT transitions and optical end-absorptions [16]. We take this
as strong evidence for particularly efficient electronic communication within the
bicyclic core of 10. The CT absorptions of 10 disappear upon acidification and are
regenerated unchanged upon neutralization (Fig. 9).
2.6. Electrochemistry. The electron-accepting power of the novel dehydroannulenes
and expanded radialenes was quantified by cyclic voltammetry (CV) and rotating-disc
voltammetry (RDV). The measurements were conducted in both THF and CH2Cl2
solutions on a glassy-C working electrode with 0.1m Bu4NPF6 as the supporting
‡
electrolyte. The potentials are referred to the ferricinium/ferrocene (Fc /Fc) couple as
the internal standard. The results obtained in THF are shown in the Table; data
obtained in CH2Cl2 do not differ much [27].
The CV of anilino-substituted [18]annulene 6 features two well-resolved reversible
one-electron reduction steps (À1.36 and À1.72 V in THF; Table) demonstrating the
electron-acceptor properties of the central C30 core. The two reduction steps occur at
more negative potentials than those of the silyl-substituted [18]annulene 2 (À1.12 and
À1.52 V) [21b][23], which is readily explained by the higher electron density in the all-
C core inflicted by the six anilino groups. Additionally, the CV of 6 shows an
irreversible third reduction step at À2.27 V (peak potential at 0.1 VsÀ1) and a
reversible, two-electron oxidation step at ‡0.25 V; the latter can be attributed to the
oxidation of two of the six anilino groups. The remaining anilino groups were oxidized
in an irreversible, unresolved peak whose potential was observed at ‡0.4 V (at
0.1 VsÀ1). The redox properties of [12]annulene 5 could, unfortunately, not be studied
due to its instability.

Helvetica Chimica Acta Vol. 87 (2004)
1147
Fig. 9. UV/VIS Spectra of bicyclic radiaannulene 10 in pure CDCl3 and upon acidification with TsOH. The
spectrum obtained after neutralization with Et3N is virtually identical to that shown in pure CDCl3.
The electrochemical behavior of hexaanilino-substituted radiaannulene 8 in THF is
characterized by two reversible, one-electron reduction steps at À1.37 and À1.67 V
(Table), values that are similar to those of 6, followed by two irreversible reduction
steps at À1.85 and À2.15 V. Two irreversible one-electron uptakes are found at ‡0.38
and ‡0.54 V that are attributed to the oxidation of the anilino groups. The redox
properties of dianilino-substituted radiaannulene 7 are quite similar to those of
hexaanilino derivative 8. Two reversible one-electron reductions are observed at À1.20
and À1.47 V (THF; Table), which are less-negative potentials than those of 8 due to
the smaller number of electron-donating anilino groups. Several irreversible reduction
transfers are detected at À1.86, À1.94, and À2.22 V, and one irreversible two-electron
oxidation step is found at ‡0.34 V for the oxidation of the anilino groups. The
tetraanilino-dinitro-substituted radiaannulene 9 displays four reversible one-electron
reduction steps at À1.13, À1.38, À1.73, and À1.81 V, followed by an irreversible
reduction at À2.33 V (THF; Table). An irreversible oxidation step for the anilino
groups is observed at ‡0.44 V. The assignment of the four reversible reductions is not
unequivocally possible, but it is likely that the first two reductions occur on the
conjugated all-C core and the last two reductions on the 4-nitrophenyl groups [30].
The bicyclic octaanilino-substituted radiaannulene 10 shows three well-separated,
one-electron-reduction steps at À0.99, À1.36, and À1.78 V (Table). Remarkably, these
potentials are less negative than those measured for hexaanilino-substituted macro-
cycles such as 6 and 8, which already indicates that the bicyclic all-C core has
exceptional electron-acceptor properties. Two irreversible oxidation peaks for the
anilino groups are observed at ‡0.48 and ‡0.57 V. Bicyclic radiaannulene 11, lacking
anilino donor groups, displays an extremely low first reduction potential at À0.83V

1148
Helvetica Chimica Acta Vol. 87 (2004)
Table. Cyclic Voltammetry (CV) and Rotating-Disk-Voltammetry Data in THF (‡ 0.1m Bu4NPF6). Potentials vs.
‡
Fc/Fc . Working electrode: glassy-C electrode; counter electrode: Pt; reference electrode: Ag/AgCl. Scan rate:
0.1 V sÀ1
Cyclic Voltammetry
Rotating-Disk Voltammetry
E8/Va)
DEp/mV
Ep/Vb)
E1/2/V
Slope/mV
6
7
‡ 0.25
À 1.36
À 1.72
120
75
100
À 2.27
‡ 0.34
‡ 0.41 (2 eÀ)
60
70
80
À 1.20
À 1.47
90
80
À 1.22 (1 eÀ)
À
À 1.53(1 e
À 1.91
)
À 1.86
À 1.94
À 2.22
8
‡ 0.54
‡ 0.40 (2 eÀ)
‡ 0.28 (2 eÀ)
À 1.29 (1 eÀ)
80
3
80
‡ 0.38
5
À 1.37
À 1.67
90
90
c
)
À 1.85
À 2.15
‡ 0.44
c
9
)
À 1.1370
À 1.38
À 1.12 (1 eÀ)
80
100
120
80
70
À 1.38 (1 eÀ)
À
À 1.7360
À 1.81
À 1.73(2 e
)
À 2.33
10
11
‡ 0.57
‡ 0.48
‡ 0.37 (8 eÀ)
À 1.00 (1 eÀ)
À 1.37 (1 eÀ)
À 1.87 (1 eÀ)
80
80
70
À 0.99
À 1.36
À 1.78
80
80
90
À 0.83100
À 0.89
120
c
À 1.19
125
125
125
)
À 1.62
À 1.75
a) E8 ˆ (Epc ‡ Epa)/2, where Epc and Epa correspond to the cathodic and anodic peak potentials, respectively.
b) Ep ˆ Irreversible peak potential. c) Unresolved further waves.
(Table). This is the lowest value observed for any macrocyclic TEE oligomer and is
even lower than the first reduction potential of buckminsterfullerene C60 (À1.02 V
under comparable conditions [20]), which is touted as a very good electron acceptor.
3. Conclusions. Acetylenic molecular scaffolding by using tetraethynylethene
building blocks provides access to unprecedented families of all-C macrocycles
featuring exceptional properties. In this paper, a new class of all-C sheets, the
perethynylated mono- (C30 core) and bicyclic (C50 core) radiaannulenes are introduced
for the first time. These compounds can be stored at room temperature in the air for
months without decomposition. Electrochemical (CVand RDV) analysis demonstrates

Helvetica Chimica Acta Vol. 87 (2004)
1149
that these macrocycles are exceptional electron acceptors. Thus, bicyclic radiaannulene
11, possessing eight peripheral 3,5-di(tert-butyl)phenyl substituents, is reversibly
‡
reduced at À0.83V in THF ( vs. Fc /Fc), making it a better electron acceptor than
buckminsterfullerene C60 under comparable conditions. In previous work, we had
shown that peripheral dialkylanilino substituents dramatically enhance the stability and
optoelectronic properties of perethynylated expanded radialenes [16]. Further
evidence in this direction was obtained in this work. A novel photochemical access
to (Z)-bisdeprotected TEEs paved the way to the synthesis of anilino-substituted
dehydroannulenes 5 and 6. Both mono- and bicyclic radiaannulenes with peripheral
anilino groups were also prepared in this work. The combined study of all of these
anilino-substituted acetylenic macrocycles (annulenes, radialenes, radiaannulenes)
allows the following conclusions concerning the beneficial effects of the donor groups:
i) they increase the solubility of the macrocycles, ii) they provide remarkable
stabilization of the electron-deficient all-C cores against nucleophilic attack and
cycloadditions, and iii) they undergo strong intramolecular charge-transfer interactions
with the electron-accepting all-C cores, resulting in intense, bathochromically shifted
CT bands. The efficiency of the charge-transfer interactions strongly depends on the
structure of the all-C core, which should be further clarified by a future theoretical
study. Facile synthetic protocols, high stability, and fascinating physical properties make
the radiaannulenes interesting advanced materials for optoelectronic applications.
Accordingly, the investigation of their nonlinear optical and two-photon absorption
properties is now being pursued in collaboration.
We gratefully acknowledge financial support for this work from the ETH Research Council and the German
Fonds der Chemischen Industrie. We thank Dr. Carlo Thilgen (ETHZ) for help with the nomenclature.
Experimental Part
General. Reagents and solvents were purchased as reagent grade and used without further purification.
THF was freshly distilled under N2 from sodium/benzophenone. Hay catalyst is referred to as a freshly prepared
solution of CuCl (100 mg, 1.0 mmol) and N,N,N',N'-tetramethylethylenediamine (TMEDA; 0.15 ml, 116 mg,
1.0 mmol) in Me2CO or CH2Cl2 (25 ml). Iodoarenes 14b and 14f were commercially available; 14a [34] and 14e
[28] as well as TEEs 12 [20a], 13b [28], 13e [28], and 30 [16b] were prepared according to literature procedures.
All reactions were conducted in standard, oven-dried glassware under an inert atmosphere (N2 or Ar), except
for the Hay coupling reactions, which were conducted exposed to air. Evaporation and concentration in vacuo
was performed at water aspirator pressure; drying in vacuo at 10À2 Torr. Flash column chromatography (FC):
SiO2-60 (230 400 mesh ASTM, 0.040 0.063 mm; E. Merck). TLC: glass sheets coated with SiO2-60 F254 from
E. Merck; visualization with a UV lamp (254 or 366 nm). Prep. gravity GPC: BIO-RAD Beads S-X1 (pore size
200 400 mm) as stationary phase at ambient pressure and temp. M.p.: B¸chi B-540 melting-point apparatus in
open capillaries; uncorrected. Some melting/decomposition points could not be determined due to the dark
color of the solid. UV/VIS Spectra: Cary-5 spectrometer; absorption maxima in nm and molar extinction
coefficients in mÀ1 cmÀ1; sh ˆ shoulder. IR Spectra: Perkin-Elmer FT-IR 1600 spectrometer; KBr pellet, soln. in
1
CHCl3, or film. H-NMR Spectra: Varian GEMINI 300 spectrometer at 300 MHz in CDCl3 or (CD3)2NCDO;
chemical shift d [ppm], coupling constant J (Hz); residual protic solvent CHCl3 (7.24 ppm) and (CHD2)2NCDO
(2.74 ppm) used as internal reference. 13C-NMR Spectra: Varian GEMINI 300 spectrometer at 75 MHz or
Varian GEMINI 500 instrument at 125 MHz; CDCl3 (77.00 ppm) and (CD3)2NCDO (30.1 ppm) as reference
signals. EI-MS (70 eV): VG-Tribid instrument; MALDI-TOF-MS: Bruker Reflex with DCTB ({(2E)-3-[4-(tert-
butyl)phenyl]-2-methylprop-2-enylidene}malononitrile) as matrix; high-resolution (HR) MALDI-MS: Ion
¾
Spec Ultima FT-ICR spectrometer (with DCTB as matrix). Elemental analyses were performed by the
Mikrolabor at the Laboratorium f¸r Organische Chemie, ETH Z¸rich, with a LECO CHN/900 instrument.

1150
Helvetica Chimica Acta Vol. 87 (2004)
Electrochemistry. The electrochemical experiments were carried out at 208 in THF or CH2Cl2 containing
0.1m Bu4NPF6 in a classical three-electrode cell. The working electrode was a glassy C disk electrode (3mm in
diameter) used either in a motionless mode for CV (0.1 to 10 V sÀ1) or as rotating-disk electrode for RDV. The
counter electrode was Pt electrode, and the pseudo-reference electrode used was a Pt wire. All potentials are
‡
referenced to the ferricinium/ferrocene (Fc /Fc) couple used as an internal standard. The accessible range of
‡
‡
potentials on the glassy C electrode was ‡1.4 to À2.4 V vs. Fc /Fc in CH2Cl2 and ‡1.1 to À2.9 V vs. Fc /Fc in
THF. The electrochemical cell was connected to a computerized multipurpose electrochemical device
AUTOLAB (Eco Chemie BV, NL-Utrecht) by the GPSE software running on a personal computer.
N,N-Dibutyl-4-iodoaniline (14c). To 4-iodoaniline (2.0 g, 9.1 mmol) and 1-iodobutane (3.5 ml, 5.5 g,
30.1 mmol) in DMF (25 ml), Na2CO3 (1.7 g, 16.0 mmol) was added, and the mixture was heated to 958 for 20 h.
After cooling to r.t., the mixture was poured into H2O (100 ml) and extracted with AcOEt (2 Â 100 ml). The
combined org. layers were washed with H2O (2 Â 50 ml) and sat. aq. NaCl soln. (50 ml), dried (MgSO4), and
evaporated in vacuo. Filtration of the residue through a plug (SiO2; hexane) gave 14c (2.9 g, 96%). Colorless oil.
1
IR (film): 3085, 2954, 1587, 1496, 1368, 801. H-NMR (300 MHz, CDCl3): 0.92 (t, J ˆ 7.4, 6 H); 1.32 (m, 4 H);
1.50 (m, 4 H); 3 .20 (t, J ˆ 7.7, 4 H); 6.39 (d, J ˆ 9.2, 2 H); 7.39 (d, J ˆ 9.2, 2 H). 13C-NMR (75 MHz, CDCl3):
‡
‡
14.10; 20.38; 29.25; 50.72; 75.23; 113.89; 137.45; 147.42. EI-MS: 331 (40, M ), 288 (100, [M À C3H7] ). Anal. calc.
for C14H22IN (331.24): C 50.77, H 6.69, N 4.23; found: C 50.71, H 6.62, N 4.26.
N,N-Dihexyl-4-iodoaniline (14d). To 4-iodoaniline (2.0 g, 9.1 mmol) and 1-iodohexane (4.5 ml, 6.17 g,
30.1 mmol) in DMF (25 ml), Na2CO3 (1.7 g, 16.0 mmol) was added, and the mixture was heated to 958 for 20 h.
After cooling to r.t., the mixture was poured into H2O (100 ml) and extracted with AcOEt (2 Â 100 ml). The
combined org. layers were washed with H2O (2 Â 50 ml) and sat. aq. NaCl soln. (50 ml), dried (MgSO4), and
evaporated in vacuo. Filtration of the residue through a plug (SiO2; hexane) afforded 14d (3.1 g, 88%).
Colorless oil. IR (film): 3080, 2925, 1589, 1496, 1367, 802. 1H-NMR (300 MHz, CDCl3): 0.88 (t, J ˆ 6.6, 6 H); 1.28
(m, 12 H); 1.53( m, 4 H); 3 .19 (t, J ˆ 7.7, 4 H); 6.38 (d, J ˆ 9.0, 2 H); 7.39 (d, J ˆ 9.0, 2 H). 13C-NMR (75 MHz,
‡
CDCl3): 14.14; 22.74; 26.84; 27.06; 31.75; 50.98; 75.27; 113.84; 137.42; 147.36. EI-MS: 387 (35, M ), 316 (100,
‡
[M À C5H11] ). Anal. calc. for C18H30IN (387.35): C 55.82, H 7.81, N 3.62; found: C 55.80, H 7.86, N 3.76.
N,N-Dimethyl-4-{(3E)-6-[4-(dimethylamino)phenyl]-3,4-bis[(triisopropylsilyl)ethynyl]hex-3-ene-1,5-diyn-
1-yl})benzenamine (13a) [28]. To a degassed soln. of 14a [34] (340 mg, 1.38 mmol) in (i-Pr)2NH (15 ml), 12
[20a] (300 mg, 0.68 mmol), [PdCl2(PPh3)2] (30 mg, 0.043 mmol), and CuI (15 mg, 0.079 mmol) were added, and
the mixture was stirred for 18 h at r.t. Hexane (50 ml) was added to the deep-red suspension that was filtered
through a plug (SiO2; CH2Cl2). The brown solid obtained by evaporation in vacuo was purified by FC (SiO2;
hexane/CH2Cl2 1:1) to give 13a (388 mg, 85%; [28]: 43%). Orange solid with anal. data identical to those
reported in [28].
N,N-Dibutyl-4-{(3E)-6-[4-(dibutylamino)phenyl]-3,4-bis[(triisopropylsilyl)ethynyl]hex-3-ene-1,5-diyn-1-
yl}benzenamine (13c). To a degassed soln. of 14c (190 mg, 0.58 mmol) in (i-Pr)2NH (10 ml), 12 [20a] (130 mg,
0.29 mmol), [PdCl2(PPh3)2] (20 mg, 0.03mmol), and CuI (10 mg, 0.05 mmol) were added, and the mixture was
stirred for 18 h at r.t. Hexane (50 ml) was added to the deep-red suspension that was filtered through a plug
(SiO2; CH2Cl2). The brown solid obtained by evaporation in vacuo was purified by FC (SiO2; hexane/CH2Cl2
6 :1) to yield 13c (190 mg, 78%). Orange solid. Mp 73.0 75.48. UV/VIS (CHCl3): 299 (40000), 476 (46000). IR
(KBr): 2928, 2863, 2195, 2138, 1602, 1520. 1H-NMR (300 MHz, CDCl3): 0.96 (t, J ˆ 7.2, 12 H); 1.13( s, 42 H); 1.3 5
(m, 8 H); 1.56 (m, 8 H); 3 .27 (t, J ˆ 7.8, 8 H); 6.53( d, J ˆ 8.9, 4 H); 7.29 (d, J ˆ 8.9, 4 H). 13C-NMR (75 MHz,
CDCl3): 11.49; 14.10; 18.83; 20.40; 29.45; 50.70; 86.92; 99.87; 100.12; 104.58; 108.49; 110.92; 115.55; 133.06;
‡
148.05. EI-MS: 842 (100, M ). Anal. calc. for C56H86N2Si2 (843.48): C 79.74, H 10.28, N 3.32; found: C 79.69,
H 10.30, N 3.23.
N,N-Dihexyl-4-{(3E)-6-[4-(dihexylamino)phenyl]-3,4-bis[(triisopropylsilyl)ethynyl]hex-3-ene-1,5-diyn-1-
yl}benzenamine (13d). To a degassed soln. of 14d (230 mg, 0.59 mmol) in (i-Pr)2NH (10 ml), 12 [20a] (130 mg,
0.29 mmol), [PdCl2(PPh3)2] (20 mg, 0.03mmol), and CuI (10 mg, 0.05 mmol) were added, and the mixture was
stirred for 18 h at r.t. Hexane (20 ml) was added to the deep-red suspension that was filtered through a plug
(SiO2; CH2Cl2). The brown solid obtained by evaporation in vacuo was purified by FC (SiO2; hexane/CH2Cl2
4 :1) to provide 13d (210 mg, 76%). Orange solid. Mp 75.1 75.98. UV/VIS (CHCl3): 300 (36000), 476 (42000).
IR (KBr): 2928, 2861, 2195, 2138, 1602, 1520. 1H-NMR (300 MHz, CDCl3): 0.92 (t, J ˆ 6.3, 12 H); 1.15 (s, 42 H);
1.33 ( m, 24 H); 1.59 (m, 8 H); 3 .28 t(, J ˆ 7.5, 8 H); 6.54 (d, J ˆ 9.0, 4 H); 7.31 (d, J ˆ 9.0, 4 H). 13C-NMR
(75 MHz, CDCl3): 11.48; 14.14; 18.82; 22.77; 26.87; 27.26; 31.77; 50.97; 86.92; 99.82; 100.12; 104.59; 108.46;
‡
110.89; 115.57; 133.05; 148.01. MALDI-MS: 954 (100, M ). Anal. calc. for C64H102N2Si2 (955.69): C 80.43,
H 10.76, N 2.93; found: C 80.20, H 10.87, N 2.85.

Helvetica Chimica Acta Vol. 87 (2004)
1151
Triisopropyl{(3E)-6-(naphthalen-1-yl)-3-[(naphthalen-1-yl)ethynyl]-4-[(triisopropylsilyl)ethynyl]hex-3-
ene-1,5-diyn-1-yl}silane (13f). To a degassed soln. of 14f (384 mg, 1.51 mmol) in (i-Pr)2NH (20 ml), 12 [20a]
(330 mg, 0.76 mmol), [PdCl2(PPh3)2] (40 mg, 0.06 mmol), and CuI (20 mg, 0.1 mmol) were added, and the
mixture was stirred for 16 h at r.t. Hexane (50 ml) was added to the thick orange suspension that was filtered
through a plug (SiO2; hexane/CH2Cl2). The orange solid obtained by evaporation in vacuo was purified by
recrystallization from EtOH/PhMe to give 13f (377 mg, 72%). Mp 182 1838. UV/VIS (CHCl3): 306 (23700),
408 (35800), 429 (33800). IR (KBr): 2936, 2857, 2196, 2140, 1457, 1399, 1189, 1147, 1088, 996, 881, 794, 766, 677,
663, 643, 582. 1H-NMR (300 MHz, CDCl3): 1.15 (s, 42 H); 7.44 (m, 2 H); 7.53( m, 4 H); 7.71 (m, 2 H); 7.85 (m,
4 H); 8.41 (m, 2 H). 13C-NMR (75 MHz, CDCl3): 11.44; 18.81; 92.79; 96.99; 102.38; 103.76; 116.82; 120.24;
‡
125.04; 126.30; 126.41; 126.81; 128.12; 129.43; 130.59; 133.01; 133.33. EI-MS: 688 (100, M ). Anal. calc. for
C48H56Si2 (689.14): C 83.66, H 8.19; found: C 83.49, H 8.33.
N,N-Dimethyl-4-{(3Z)-6-[4-(dimethylamino)phenyl]-3,4-bis[(triisopropylsilyl)ethynyl]hex-3-ene-1,5-diyn-
1-yl}benzenamine (15a). A soln. of 13a (300 mg, 0.44 mmol) in Et2O (180 ml) was irradiated with a medium-
pressure Hg lamp (125 W) for 2 h at r.t. Evaporation in vacuo gave an orange solid that was subjected to FC
(SiO2; hexane/CH2Cl2 2 :1) to yield 15a (123mg, 41%) besides recovered 13a (160 mg, 53%). Orange solid. Mp
159 1608. UV/VIS (CHCl3): 278 (sh, 27400), 299 (31100), 400 (30000), 460 (31300). IR (KBr): 2941, 2861,
2179, 2126, 1606, 1520, 1367. 1H-NMR (300 MHz, CDCl3): 1.11 (s, 42 H); 2.98 (s, 12 H); 6.61 (d, J ˆ 9.0, 4 H);
7.36 ( d, J ˆ 9.0, 4 H). 13C-NMR (75 MHz, CDCl3): 11.47; 18.84; 40.24; 87.38; 100.18; 100.28; 104.27; 109.80;
‡
111.66; 115.41; 132.86; 150.22. EI-MS: 674 (100, M ). Anal. calc. for C44H62N2Si2 (675.16): C 78.28, H 9.26,
N 4.15; found: C 78.27, H 9.27, N 4.15.
Triisopropyl{(3Z)-3,4-bis[(4-nitrophenyl)ethynyl]-6-(triisopropylsilyl)hex-3-ene-1,5-diyne-1-yl}silane (15b).
A soln. of 13b [28] (75 mg, 0.11 mmol) in Et2O (160 ml) was irradiated with a medium-pressure Hg lamp
(125 W) for 5 h at r.t. Evaporation in vacuo provided a residue that was subjected to FC (SiO2; hexane/CH2Cl2
2 :1) to give 15b (29 mg, 39%) and recovered 13b (37 mg, 52%). Yellow solid. Mp 172 1738. UV/VIS (CHCl3):
1
318 (36600), 404 (30300). IR (KBr): 2941, 2863, 1592, 1519, 1340, 850, 828, 683. H-NMR (300 MHz, CDCl3):
1.12 (s, 42 H); 7.59 (d, J ˆ 8.9, 4 H); 8.21 (d, J ˆ 8.9, 4 H). 13C-NMR (75 MHz, CDCl3): 11.33; 18.72; 91.71; 96.21;
‡
102.45; 104.51; 117.88; 123.48; 129.03; 132.40; 147.33. EI-MS: 678 (100, M ). Anal. calc. for C40H50N2O4Si2
(679.02): C 70.76, H 7.42, N 4.13; found: C 70.81, H 7.56, N 4.22.
4,4',4'',4'''-[Cyclododeca-1,7-diene-3,5,9,11-tetrayne-1,2,7,8-tetrayltetrakis(ethyne-2,1-diyl)]tetrakis[N,N-di-
methylaniline] (5) and 4,4',4'',4''',4'''',4'''''-[Cyclooctadeca-1,7,13-triene-3, 5,9,11,15,17-hexayne-1,2,7,8,13,14-hex-
aylhexakis(ethyne-2,1-diyl)]hexakis[N,N-dimethylaniline] (6). To
a cooled (08) soln. of 15a (100 mg,
0.148 mmol) in moist THF (10 ml), Bu4NF (0.44 ml of a 1.0m soln. in THF, 0.44 mmol) was added. After
stirring for 10 min, TLC control indicated that the deprotection was complete. CH2Cl2 (50 ml) was added, and
the soln. was filtered through a plug (SiO2; CH2Cl2). Evaporation in vacuo provided a brownish oil that was
dissolved in Me2CO (150 ml). Hay catalyst (3ml) was added, and the mixture was stirred under air at r.t. for 2 h,
after which time TLC control indicated that all the deprotected starting material had been consumed. The deep-
purple soln. was filtered through a plug (SiO2) and concentrated in vacuo to a volume of ca. 100 ml. Hexane
(200 ml) was added, and the soln. was once again concentrated to ca. 100 ml, resulting in the formation of a black
precipitate. The remaining soln. was decanted off, and the residue was subjected to FC (hexane/CH2Cl2 1 :1 !
CH2Cl2/Et3N 10 :1) to yield 5 (1.1 mg, 2.1%) and 6 (11.8 mg, 22%).
Data of 5: Deep-purple solid. UV/VIS (CHCl3): 327 (53400), 431 (24100), 518 (35100), 566 (sh, 20600).
1H-NMR (500 MHz, (CD3)2NCDO): 3.04 (s, 24 H); 6.78 (d, J ˆ 9.0, 8 H); 7.36 (d, J ˆ 9.0, 8 H). 13C-NMR
(125 MHz, (CD3)2NCDO): 39.92; 85.28; 87.85; 95.32; 107.12; 107.62; 112.66; 120.83; 133.80; 152.14. MALDI-
‡
‡
‡
TOF-MS: 720 (100, M ). HR-FT-ICR-MALDI-MS: 720.3253 (M ; C52H40N4 ; calc. 720.3253).
Data of 6: Deep-purple solid. UV/VIS (CHCl3): 297 (69800), 366 (32600), 518 (105200), 533 (sh, 99000).
IR (KBr): 3037, 2990, 2140, 1617, 1456, 815, 797, 552. 1H-NMR (500 MHz, (CD3)2NCDO): 3.10 (s, 36 H); 6.89 (d,
J ˆ 9.0, 12 H); 7.63( d, J ˆ 9.0, 12 H). 13C-NMR (125 MHz, (CD3)2NCDO): 39.98; 83.22; 86.23; 87.26; 107.71;
‡
107.90; 112.76; 115.84; 134.03; 152.26. MALDI-TOF-MS: 1080 (100, M ). HR-FT-ICR-MALDI-MS: 1080.4884
‡
‡
(M , C78H60N6 ; calc. 1080.4879). Anal. calc. for C78H60N6 (1081.37): C 86.64, H 5.59, N 7.77; found: C 86.70,
H 5.77, N 7.60.
N,N-Dihexyl-4-[(trimethylsilyl)ethynyl]aniline (20). To a deoxygenated soln. of 14d (1.5 g, 3.87 mmol) in
(i-Pr)2NH (50 ml), 19 (1.27 ml, 0.86 g, 8.76 mmol), [PdCl2(PPh3)2] (80 mg, 0.11 mmol), and CuI (40 mg,
0.21 mmol) were added, and the mixture was stirred for 5 h at r.t. Hexane (50 ml) was added, and the mixture
was filtered through a plug (SiO2; CH2Cl2). The residue obtained after evaporation in vacuo was subjected to
FC (SiO2; hexane/CH2Cl2 5 :1) to yield 20 (1.33 g, 95%). Colorless oil. IR (film): 2958, 2924, 2857, 2146, 1606,
1516, 1466, 1368, 1248, 1183, 864, 758, 632. 1H-NMR (300 MHz, CDCl3): 0.21 (s, 9 H); 0.88 (t, J ˆ 6.5, 6 H); 1.29

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Helvetica Chimica Acta Vol. 87 (2004)
(m, 12 H); 1.53( m, 4 H); 3 .23 t(, J ˆ 7.8, 4 H); 6.48 (d, J ˆ 9.0, 2 H); 7.27 (d, J ˆ 9.0, 2 H). 13C-NMR (75 MHz,
CDCl3): 0.38; 14.12; 22.75; 26.85; 27.23; 31.77; 50.93; 90.95; 106.78; 108.53; 110.91; 133.11; 147.88. EI-MS: 357
‡
‡
(37, M ), 286 (100, [M À C5H11] ). Anal. calc. for C23H39NSi (357.65): C 77.24, H 10.99, N 3.92; found: C 77.41,
H 11.06, N 3.92.
4-Ethynyl-N,N-dihexylaniline (21). To 20 (1.25 g, 3.49 mmol) in THF (20 ml) and MeOH (20 ml), K2CO3
(0.96 g, 6.97 mmol) was added, and the mixture was stirred for 30 min at r.t. Hexane (50 ml) was added, and the
mixture was filtered through a plug (SiO2; AcOEt). Evaporation in vacuo gave 21 (0.98 g, 99%). Colorless oil.
IR (film): 3305, 3092, 3042, 2926, 2851, 2100, 1608, 1517, 1466, 1369, 1292, 1255, 1180, 813, 642. 1H-NMR
(300 MHz, CDCl3): 0.90 (t, J ˆ 6.8, 6 H); 1.31 (m, 12 H); 1.56 (m, 4 H); 2.94 (s, 1 H); 3.25 (t, J ˆ 7.8, 4 H); 6.52
(d, J ˆ 9.0, 2 H); 7.31 (d, J ˆ 9.0, 2 H). 13C-NMR (75 MHz, CDCl3): 14.13; 22.76; 26.87; 27.22; 31.77; 50.97; 74.37;
‡
‡
85.06; 107.33; 110.94; 133.22; 148.05. EI-MS: 285 (20, M ), 214 (100, [M À C5H11] ). Anal. calc. for C20H31N
(285.47): C 84.15, H 10.95, N 4.91; found: C 83.97, H 10.79, N 4.86.
N,N-Dihexyl-4-(3-{[4-(dihexylamino)phenyl]ethynyl}-6-(triisopropylsilyl)-4-[(triisopropylsilyl)ethynyl]-
hex-3-ene-1,5-diyn-1-yl)benzenamine (18). To a deoxygenated soln. of 22 [20a] (767 mg, 1.66 mmol) and 21
(946 mg, 3.32 mmol) in Et3N (30 ml), [PdCl2(PPh3)2] (46 mg, 0.07 mmol) and CuI (23mg, 0.12 mmol) were
added, and the mixture was stirred for 16 h at r.t. Hexane (50 ml) was added, and the mixture was filtered
through a plug (SiO2; hexane/CH2Cl2 1 :1). Evaporation in vacuo gave a brown oil that was subjected to FC
(SiO2; hexane/CH2Cl2 10 :1) to yield 18 (1.00 g, 69%). Yellow oil. UV/VIS (CHCl3): 312 (32900), 445 (58600).
IR (film): 2928, 2863, 2196, 2170, 2134, 1603, 1520, 1465, 1407, 1363, 1248, 1186, 1110, 1019, 999, 862, 811.
1H-NMR (300 MHz, CDCl3): 0.25 (s, 9 H); 0.90 (t, J ˆ 6.8, 12 H); 1.13( s, 21 H); 1.3 2 (m, 24 H); 1.57 (m, 8 H);
3.27 (t, J ˆ 7.7, 8 H); 6.52 (d, J ˆ 9.0, 2 H); 6.55 (d, J ˆ 9.0, 2 H); 7.33 (d, J ˆ 9.0, 2 H); 7.35 (d, J ˆ 9.0, 2 H).
13C-NMR (75 MHz, CDCl3): 0.09; 11.55; 14.14; 18.81; 22.75; 26.86; 27.27; 31.76; 50.96; 86.39; 86.82; 99.90;
100.88; 100.93; 102.35; 103.00; 104.59; 108.20; 108.25; 110.90; 110.99; 111.80; 120.08; 133.28; 148.22; 148.26.
‡
MALDI-TOF-MS: 871 (100, M ). Anal. calc. for C58H90N2Si2 (871.52): C 79.93, H 10.41, N 3.21; found: C 79.87,
H 10.30, N 3.02.
4-((3Z)-4-{[4-(Dimethylamino)phenyl]ethynyl}-12-phenyl-10-(phenylethynyl)-3-{8-phenyl-6-(phenyl-
ethynyl)-5-[(triisopropylsilyl)ethynyl]oct-5-ene-1,3,7-triyn-1-yl}-9-[(triisopropylsilyl)ethynyl]dodeca-3,9-diene-
1,5,7,11-tetrayn-1-yl)-N,N-dimethylbenzenamine (17). According to the protocol described for 5/6, 15a (70 mg,
0.10 mmol) was desilylated with Bu4NF. Also, to a soln. of 23 [20a] (340 mg, 0.79 mmol) in THF (20 ml) and
MeOH (10 ml), K2CO3 (213mg, 1.55 mmol) was added, and the mixture was stirred for 2.5 h at r.t. After
complete Me3Si deprotection (TLC), CH2Cl2 (50 ml) was added, and the mixture was filtered through a plug
(SiO2; CH2Cl2). Evaporation in vacuo left a brown oil. Crude deprotected 15a and 23 were dissolved in Me2CO
(150 ml), and Hay catalyst (10 ml) was added. The mixture was stirred for 1.5 h at r.t. exposed to air, filtered
through a plug (SiO2; acetone), and evaporated in vacuo. The residual brown oil was subjected to FC (hexane/
AcOEt 4 :1 ! AcOEt) to yield 17 (70 mg, 57%). Reddish-brown solid. UV/VIS (CHCl3): 302 (81500), 367
(57400), 460 (58400), 543 (sh, 31400). IR (KBr): 2936, 2857, 2162, 1603, 1521, 1441, 1363, 1161, 1108, 813, 754,
687. 1H-NMR (300 MHz, CDCl3): 1.11 (s, 42 H); 23.01 (s, 12 H); 6.62 (d, J ˆ 9.6, 4 H); 7.33 7.62 (m, 24 H).
13C-NMR (75 MHz, CDCl3): 11.38; 18.76; 40.13; 82.51; 82.96; 83.86; 84.46; 86.63; 87.11; 87.33; 100.43; 100.68;
101.85; 103.11; 104.23; 108.68; 111.58; 115.43; 116.36; 121.16; 122.03; 122.30; 128.12; 128.40; 129.03; 129.23;
‡
‡
131.75; 132.04; 133.14; 150.55. FT-ICR-MALDI-MS: 1261 (27, [M ‡ K] ), 1245 (100, [M ‡ Na] ), 1222 (14,
‡
‡
‡
M ). HR-FT-ICR-MALDI-MS: 1222.6003( M , C88H82N2Si2 ; calc. 1222.6017). Anal. calc. for C88H82N2Si2
(1223.80): C 86.37, H 6.75, N 2.29; found: C 86.18, H 6.94, N 2.35.
4-((9Z)-18-[4-(Dihexylamino)phenyl]-3,16-bis{[4-(dihexylamino)phenyl]ethynyl}-9,10-bis{[4-(dimethyl-
amino)phenyl]ethynyl}-4,15-bis[(triisopropylsilyl)ethynyl]octadeca-3,9,15-triene-1,5,7,11,13,17-hexayn-1-yl)-
N,N-dihexylbenzenamine (25). To a soln. of 18 (387 mg, 0.44 mmol) in THF (20 ml) and MeOH (10 ml), K2CO3
(121 mg, 0.88 mmol) was added, and the mixture was stirred for 2.5 h at r.t. After complete Me3Si deprotection,
CH2Cl2 (50 ml) was added, and the mixture was filtered through a plug (SiO2; CH2Cl2). Evaporation in vacuo
left a brown oil that was taken up in Me2CO (100 ml). To this was added a soln. of 15a (50 mg, 0.074 mmol) that
had been bis-silyl-deprotected with Bu4NF as described for 5/6, in Me2CO (50 ml). Hay catalyst (10 ml) was
added, and the mixture was stirred for 1 h at r.t. exposed to air. The soln. was filtered through a plug (SiO2;
Me2CO), and evaporation in vacuo gave a solid that was purified by FC (SiO2; hexane/CH2Cl2 3:1 ! 1.5 :1) to
yield 25 (47 mg, 32%). Deep-purple waxy solid. UV/VIS (CHCl3): 301 (96700), 486 (98800). IR (KBr): 2924,
2857, 2160, 1602, 1521, 1363, 1183, 1107, 812. 1H-NMR (300 MHz, CDCl3): 0.81 0.92 (m, 24 H); 1.11 (s, 42 H);
1.23 1.31 ( m, 48 H); 1.53( m, 16 H); 2.99 (s, 12 H); 3.16 3.29 (m, 16 H); 6.50 6.62 (m, 12 H); 7.31 7.42 (m,
12 H). 13C-NMR (75 MHz, CDCl3): 11.55; 14.15; 18.89; 22.77; 26.87; 27.3; 31.76; 40.17; 50.97; 82.17; 83.42; 83.66;
86.43; 87.03; 87.13; 87.74; 100.47; 102.87; 102.94; 103.82; 107.72; 108.16; 109.31; 109.81; 110.90; 111.30; 111.64;

Helvetica Chimica Acta Vol. 87 (2004)
1153
115.92; 123.31; 133.12; 133.42; 133.70; 148.34; 148.52; 150.40 (35 out of 36 signals). FT-ICR-MALDI-MS: 1956
‡
‡
(39, M ), 1799 (100, [M À C9H21Si] ). Anal. calc. for C136H182N6Si2 (1957.11): C 83.46, H 9.37, N 4.29; found:
C 83.43, H 9.50, N 4.44.
4-((3Z)-4-{[4-(Dimethylamino)phenyl]ethynyl}-12-(4-nitrophenyl)-10-[(4-nitrophenyl)ethynyl]-3-{8-(4-ni-
trophenyl)-6-[(4-nitrophenyl)ethynyl]-5-[(triisopropylsilyl)ethynyl]oct-5-ene-1,3,7-triyn-1-yl}-9-[(triisopropylsi-
lyl)ethynyl]dodeca-3,9-diene-1,5,7,11-tetrayn-1-yl)-N,N-dimethylbenzenamine (26). TEE 15a (90 mg,
0.13mmol) was bis-deprotected with Bu 4NF as described for 5/6. Also, Me3Si deprotection of 24 [28]
(417 mg, 0.8 mmol) with K2CO3 in THF/MeOH was performed as described for 17. The two crude deprotected
species were dissolved in Me2CO (200 ml), and Hay catalyst (20 ml) was added. The mixture was stirred for 2 h
at r.t. exposed to air, filtered through a plug (SiO2; Me2CO), and the solvents were evaporated in vacuo to yield
a brown solid. FC (3 Â hexane/AcOEt 4 :1 ! AcOEt) provided 26 (114 mg, 63%). Brown solid. UV/VIS
(CHCl3): 325 (87000), 400 (sh, 57600), 488 (49400), 594 (sh, 24800). IR (KBr): 2936, 2863, 2151, 1603, 1519,
1340, 1161, 853. 1H-NMR (300 MHz, CDCl3): 1.09 (s, 42 H); 3.03 (s, 12 H); 6.64 (d, J ˆ 9.0, 4 H); 7.42 (d, J ˆ 9.0,
4 H); 7.65 (d, J ˆ 9.0, 4 H); 7.68 (d, J ˆ 9.0, 4 H); 8.21 (d, J ˆ 9.0, 4 H); 8.22 (d, J ˆ 9.0, 4 H). 13C-NMR (75 MHz,
CDCl3): 11.33; 18.74; 40.16; 81.91; 83.85; 84.66; 85.50; 86.59; 90.47; 90.78; 98.03; 98.13; 101.09; 105.69; 106.33;
108.26; 111.64; 116.53; 118.60; 118.77; 123.51; 132.72; 128.44; 128.65; 132.46; 132.67; 133.22; 147.41; 147.49;
‡
‡
‡
150.79. FT-ICR-MALDI-MS: 1425 (100, [M ‡ Na] ), 1402 (71, M ). HR-FT-ICR-MALDI-MS: 1402.5430 (M ,
‡
C88H78N6O8Si2 ; calc. 1402.5420). Anal. calc. for C88H78N6O8Si2 (1403.79): C 75.29, H 5.60, N 5.99; found:
C 75.10, H 5.64, N 5.93.
4-{(9Z)-18-[4-(Dihexylamino)phenyl]-3,16-bis{[4-(dihexylamino)phenyl]ethynyl}-9,10-bis[(4-nitrophenyl)-
ethynyl]-4,15-bis[(triisopropylsilyl)ethynyl]octadeca-3,9,15-triene-1,5,7,11,13,17-hexayn-1-yl}-N,N-dihexylben-
zenamine (27). To a cooled (08) soln. of 15b (157 mg, 0.23mmol) in moist THF (15 ml), Bu 4NF (0.69 ml of a 1m
soln. in THF, 0.69 mmol) was added. After stirring for 10 min, TLC control indicated complete desilylation. The
soln. was diluted with CH2Cl2 (50 ml) and filtered through a plug (SiO2). The solvents were evaporated in vacuo,
and the residue was dissolved in Me2CO (100 ml). To this was added a soln. of 18 (1.266 g, 1.45 mmol) that had
been Me3Si-deprotected with K2CO3 in THF/MeOH as described for 17, in Me2CO (100 ml). Hay catalyst
(10 ml) was added, and the mixture was stirred for 1.5 h at r.t. exposed to air. Filtration through a plug (SiO2;
Me2CO), evaporation in vacuo, and FC (SiO2; hexane/CH2Cl2 3:1 ! 1:1) yielded 27 (145 mg, 32%). Brown
solid. UV/VIS (CHCl3): 311 (87400), 454 (80000). IR (KBr): 2925, 2859, 2158, 1601, 1521, 1341, 1186, 1108, 852,
1
812. H-NMR (300 MHz, CDCl3): 0.83( t, J ˆ 6.6, 12 H); 0.89 (t, J ˆ 6.6, 12 H); 1.12 (s, 42 H); 1.23( m, 24 H);
1.31 (m, 24 H); 1.53( m, 16 H); 3.20 (t, J ˆ 7.8, 8 H); 3.27 (t, J ˆ 7.7, 8 H); 6.52 (d, J ˆ 9.1, 4 H); 6.53( d, J ˆ 9.1,
4 H); 7.3 5 (t, J ˆ 9.1, 8 H); 7.63( d, J ˆ 8.9, 4 H); 8.21 (d, J ˆ 8.9, 4 H). 13C-NMR (75 MHz, CDCl3): 11.39; 14.02;
18.75; 22.64; 26.75; 27.14; 31.65; 50.91; 81.41; 81.98; 87.20; 87.44; 87.88; 89.15; 91.45; 97.91; 101.03; 102.46; 104.35;
104.49; 107.54; 107.80; 108.75; 110.94; 111.26; 117.63; 123.80; 124.66; 128.80; 132.44; 133.67; 133.83; 147.59;
‡
‡
‡
148.65; 148.71. FT-ICR-MALDI-MS: 1999 (49, [M ‡ K] ), 1983(92, [ M ‡ Na] ), 1960 (49, M ), 1803(100,
[M À Si(CH(CH3)2)3] ). HR-FT-ICR-MALDI-MS: 1960.2829 (M , 13C12C131H170N6O4Si2 ; calc. 1960.2822).
‡
‡
‡
Anal. calc. for C132H170N6O4Si2 (1960.97): C 80.85, H 8.74, N 4.29; found: C 81.02, H 6.68, N 4.26.
4,4'-({7,12-Bis[3-phenyl-1-(phenylethynyl)prop-2-yn-1-ylidene]cyclohexadec-1-ene-3,5,8,10,13,15-hexayne-
1,2-diyl}bis(ethyne-2,1-diyl))bis[N,N-dimethylaniline] (7). To a cooled (08) soln. of 17 (62 mg, 0.05 mmol) in
moist THF (10 ml), Bu4NF (0.15 ml of a 1.0m soln. in THF, 0.15 mmol) was added dropwise. After stirring for
10 min, TLC control indicated complete desilylation. CH2Cl2 (20 ml) was added, and the soln. was filtered
through a plug (SiO2; CH2Cl2). The solvents were evaporated in vacuo, and the residue was dissolved in Me2CO
(150 ml). Hay catalyst (5 ml) was added, and the mixture was stirred for 1 h at r.t. exposed to air. After filtration
through a plug (SiO2), the solvent was evaporated in vacuo, and the residue was subjected to FC (SiO2; hexane/
CH2Cl2 2 :1 ! 1:2) to yield 7 (22 mg, 48%). Dark-brown solid. UV/VIS (CHCl3): 312 (67500), 381 (28500), 494
(103900), 588 (sh, 31900). IR (KBr): 2146, 1600, 1522, 1362, 1180, 1085, 808, 752, 685. 1H-NMR (300 MHz,
CDCl3): 3.01 (s, 12 H); 6.62 (d, J ˆ 9.3, 4 H); 7.35 7.42 (m, 16 H); 7.54 7.60 (m, 8 H). 13C-NMR (125 MHz,
CDCl3): 40.09; 82.67; 86.06; 86.87; 86.93; 86.94; 87.18; 87.37; 88.19; 96.63; 101.01; 101.32; 105.15; 108.75; 111.70;
113.67; 116.08; 117.78; 121.94; 128.44; 129.57; 132.16; 132.29; 133.29; 150.80 (25 out of 28 signals). FT-ICR-
‡
‡
‡
MALDI-MS: 908 (100, M ). HR-FT-ICR-MALDI-MS: 908.3180 (M , C70H40N2 ; calc. 908.3191). Anal. calc.
for C70H40N2 (909.10): C 92.48, H 4.43, N 3.08; found: C 92.37, H 4.49, N 3.04.
4,4',4'',4'''-[(11,12-Bis{[4-(dimethylamino)phenyl]ethynyl}cyclohexadec-11-ene-2,4,7,9,13,15-hexayne-1,6-
diylidene)bis(penta-1,4-diyne-1,5-diyl-3-ylidene)]tetrakis[N,N-dihexylaniline] (8). To a cooled (08) soln. of 25
(45 mg, 0.023mmol) in moist THF (15 ml), Bu 4NF (0.07 ml of a 1.0m soln. in THF, 0.07 mmol) was added
dropwise. After stirring for 10 min, CH2Cl2 (50 ml) was added, and the soln. was filtered through a plug (SiO2;
CH2Cl2). The residue obtained by evaporation in vacuo was dissolved in Me2CO (150 ml), and Hay catalyst

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Helvetica Chimica Acta Vol. 87 (2004)
(10 ml) was added. After stirring for 1 h at r.t. exposed to air, the soln. was filtered through a plug (SiO2).
Evaporation in vacuo and FC (SiO2; hexane/CH2Cl2 2 :1 ! 1:2) afforded 8 (11.9 mg, 32%). Deep-purple waxy
solid. UV/VIS (CHCl3): 304 (82400), 521 (106100), 614 (99900). IR (CHCl3): 2957, 2930, 2858, 2164, 1603, 1522,
1
1366, 1189, 1086, 986, 817. H-NMR (300 MHz, CDCl3): 0.88 0.89 (m, 24 H); 1.26 1.54 (m, 48 H); 1.57 (m,
16 H); 3.00 (s, 12 H); 3.26 (m, 16 H); 6.53 6.62 ( m, 12 H); 7.37 7.42 (m, 12 H). 13C-NMR (75 MHz, CDCl3):
14.18; 22.78; 26.87; 27.28; 31.76; 40.17; 51.02; 83.58; 84.85; 86.00; 86.05; 86.51; 87.24; 87.33; 89.79; 96.85; 103.58;
103.71; 104.00; 107.50; 109.10; 110.41; 111.07; 111.59; 115.26; 117.36; 133.06; 133.72; 133.85; 148.57; 146.61;
‡
‡
‡
150.44 (32 out of 34 signals). FT-ICR-MALDI-MS: 1681 (2, [M ‡ K] ), 1665 (12, [M ‡ Na] ), 1642 (100, M ).
HR-FT-ICR-MALDI-MS: 1642.1141 (M , 13C12C117H140N6 ; calc. 1642.1139).
‡
‡
4,4'-[(7,12-Bis{3-(4-nitrophenyl)-1-[(4-nitrophenyl)ethynyl]prop-2-yn-1-ylidene}cyclohexadec-1-ene-
3,5,8,10,13,15-hexayne-1,2-diyl)bis(ethyne-2,1-diyl)]bis[N,N-dimethylaniline] (28). Starting from 26 and accord-
ing to the protocol described for the synthesis of 8, traces of unstable 28 were isolated. FT-ICR-MALDI-MS:
‡
‡
‡
1088 (100, M ). HR-FT-ICR-MALDI-MS: 1088.2639 (M , C70H36N6O8 ; calc. 1088.2595).
4,4',4'',4'''-[{11,12-Bis[(4-nitrophenyl)ethynyl]cyclohexadec-11-ene-2,4,7,9,13,15-hexayne-1,6-diylidene}bis-
(penta-1,4-diyne-1,5-diyl-3-ylidene)]tetrakis[N,N-dihexylaniline] (9). To a cooled (08) soln. of 27 (145 mg,
0.074 mmol) in moist THF (15 ml), Bu4NF (0.22 ml of a 1.0m soln. in THF, 0.22 mmol) was added dropwise.
After stirring for 10 min, CH2Cl2 (50 ml) was added, and the soln. was filtered through a plug (SiO2; CH2Cl2).
The residue obtained by evaporation in vacuo was dissolved in Me2CO (200 ml), and Hay catalyst (10 ml) was
added. After stirring for 1.5 h at r.t. exposed to air, the soln. was filtered through a plug (SiO2; Me2CO).
Evaporation in vacuo and FC (SiO2; hexane/CH2Cl2 3:1 ! 1:1) gave 9 (16.6 mg, 14%). Deep-purple waxy
solid. UV/VIS (CHCl3): 303 (85500), 542 (98800), 614 (89300). IR (CHCl3): 2957, 2930, 2858, 2156, 1601, 1522,
1349, 1187, 1130, 854, 817. 1H-NMR (300 MHz, CDCl3): 0.87 (t, J ˆ 6.8, 24 H); 1.30 (m, 48 H); 1.57 (m, 16 H);
3.27 (t, J ˆ 7.5, 16 H); 6.55 (d, J ˆ 8.4, 8 H); 7.38 (d, J ˆ 8.7, 8 H); 7.65 (d, J ˆ 9.0, 4 H); 8.20 (d, J ˆ 9.0, 4 H).
13C-NMR (125 MHz, CDCl3): 14.03; 22.67; 26.78; 27.22; 29.71; 31.68; 51.01; 84.02; 84.52; 86.66; 86.95; 87.58;
87.70; 90.50; 92.11; 96.52; 98.59; 104.54; 105.47; 107.32; 107.37; 109.44; 111.21; 111.24; 116.91; 119.12; 123.83;
‡
128.35; 128.81; 132.44; 134.02; 147.71; 149.017; 149.022. FT-ICR-MALDI-MS: 1646 (100, M ). HR-FT-ICR-
‡
‡
MALDI-MS: 1644.9992 (M , C114H128N6 ; calc. 1644.9997).
Triisopropyl(17-phenyl-15-(phenylethynyl)-3-[3-phenyl-1-(phenylethynyl)prop-2-yn-1-ylidene]-8,9-bis{8-
phenyl-6-(phenylethynyl)-5-[(triisopropylsilyl)ethynyl]oct-5-ene-1,3,7-triyn-1-yl}-14-[(triisopropylsilyl)ethynyl]-
heptadeca-8,14-diene-1,4,6,10,12,16-hexayn-1-yl)silane (31). To a soln. of tetrakis(trimethylsilyl)-protected 29
[20a] (65 mg, 0.16 mmol) in THF/MeOH (1:1, 20 ml), K2CO3 (50 mg, 0.36 mmol) was added, and the mixture
was stirred for 30 min at r.t. Me2CO (50 ml) was added, and the mixture was filtered through a plug (SiO2;
Me2CO). A soln. of Me3Si-deprotected 23 (for the deprotection protocol, see synthesis of 17) [20a] (957 mg,
1.90 mmol) in Me2CO (200 ml) was added, followed by Hay catalyst (15 ml). The mixture was stirred for 2.5 h at
r.t. exposed to air, then filtered through a plug (SiO2; Me2CO), and evaporated in vacuo. FC (SiO2; hexane/
AcOEt 5 :1) gave 31 (114 mg, 39%). Red waxy solid. UV/VIS (CHCl3): 289 (101000), 373 (101000), 444 (sh,
60800), 505 (44500). IR (CHCl3): 2944, 2866, 2186, 1492, 1463, 1443, 1070, 998, 883. 1H-NMR (300 MHz,
CDCl3): 1.10 (s, 84 H); 7.33 7.37 (m, 24 H); 7.49 7.56 (m, 16 H). 13C-NMR (75 MHz, CDCl3): 11.38; 18.76;
81.83; 82.02; 86.37; 86.98; 87.07; 87.21; 101.16; 101.21; 101.44; 103.72; 114.82; 119.02; 121.83; 122.16; 122.22;
‡
128.17; 128.44; 129.20; 129.48; 131.81; 132.01. MALDI-TOF-MS: 1846 (100, M ).
4-(18-[4-(Dihexylamino)phenyl]-9,10-bis{8-[4-(dihexylamino)phenyl]-6-{[4-(dihexylamino)phenyl]ethyn-
yl}-5-[(triisopropylsilyl)ethynyl]oct-5-ene-1,3,7-triyn-1-yl}-3,16-bis{[4-(dihexylamino)phenyl]ethynyl}-4,15-
bis[(triisopropylsilyl)ethynyl]octadeca-3,9,15-triene-1,5,7,11,13,17-hexayn-1-yl)-N,N-dihexylbenzenamine (32).
To a soln. of tetrakis(trimethylsilyl)-protected 29 [20a] (35 mg, 0.085 mmol) in THF/MeOH 1:1 (20 ml),
K2CO3 (44 mg, 0.32 mmol) was added and the mixture was stirred for 15 min at r.t. Me2CO (50 ml) was added,
and the mixture was filtered through a plug (SiO2; Me2CO). A soln. of 18 (1.486 g, 1.70 mmol), which had been
Me3Si-deprotected as described for the preparation of 25, in Me2CO (150 ml) was added, followed by Hay
catalyst (15 ml). The mixture was stirred for 2.5 h at r.t. exposed to air, then filtered through a plug (SiO2;
Me2CO), and evaporated in vacuo. FC (short SiO2 column; hexane/AcOEt 10 :1), followed by gravity GPC
(Bio-Beads 1-SX; THF), afforded 32 (109 mg, 39%). Brown waxy solid. UV/VIS (CHCl3): 304 (147800), 459
(143400), 641 (sh, 43800). IR (CHCl3): 2943, 2931, 2863, 2161, 1601, 1521, 1368, 1110, 816. 1H-NMR (300 MHz,
CDCl3): 0.83( t, J ˆ 6.6, 24 H); 0.90 (t, J ˆ 6.6, 24 H); 1.10 (s, 84 H); 1.23( m, 48 H); 1.3 1 (s, 48 H); 1.54 (m,
32 H); 3.25 (m, 32 H); 6.50 (d, J ˆ 8.9, 8 H); 6.52 (d, J ˆ 8.9, 8 H); 7.26 (d, J ˆ 8.9, 8 H); 7.33 (d, J ˆ 8.9, 8 H).
13C-NMR (75 MHz, CDCl3): 11.39; 14.03; 14.08; 18.76; 22.65; 22.71; 26.76; 26.81; 27.16; 27.28; 31.67; 31.72; 50.92;
82.03; 82.70; 86.77; 87.36; 88.01; 88.99; 100.67; 102.56; 103.52; 105.14; 107.27; 108.13; 109.11; 110.93; 111.30;
‡
117.48; 124.35; 133.60; 133.78; 148.52; 148.78. MALDI-TOF-MS: 3312 (100, M ).

Helvetica Chimica Acta Vol. 87 (2004)
1155
(17-[3,5-Di-(tert-butyl)phenyl]-3-(3-[3,5-di-(tert-butyl)phenyl]-1-{[3,5-di-(tert-butyl)phenyl]ethynyl}-
prop-2-yn-1-ylidene)-8,9-bis(8-[3,5-di-(tert-butyl)phenyl]-6-{[3,5-di-(tert-butyl)phenyl]ethynyl}-5-[(triisopro-
pylsilyl)ethynyl]oct-5-ene-1,3,7-triyn-1-yl)-15-{[3,5-di-(tert-butyl)phenyl]ethynyl}-14-[(triisopropylsilyl)ethynyl]-
heptadeca-8,14-diene-1,4,6,10,12,16-hexayn-1-yl)(triisopropyl)silane (33). To a soln. of tetrakis(trimethylsilyl)-
protected 29 [20a] (50 mg, 0.11 mmol) in THF/MeOH (1:1, 20 ml), K2CO3 (38 mg, 0.27 mmol) was added and
the mixture was stirred for 30 min at r.t. Me2CO (50 ml) was added, and the mixture was filtered through a plug
(SiO2; Me2CO). A soln. of Me3Si-deprotected (for the deprotection protocol, see [16b] or the preparation of
17) 30 (953mg, 1.31 mmol) in Me 2CO (150 ml) was added, followed by Hay catalyst (15 ml). The mixture was
stirred for 1.5 h at r.t. exposed to air, then filtered through a plug (SiO2; Me2CO), and evaporated in vacuo. FC
(hexane/CH2Cl2 98 :2 ! 90 :10) afforded 33 (65 mg, 29%). Red solid. UV/VIS (CHCl3): 255 (107900), 276
(98742), 375 (97700), 413 (sh, 73900), 504 (sh, 36700). IR (CHCl3): 2965, 2866, 2186, 1588, 1464, 1364, 1248,
1
1141, 879. H-NMR (300 MHz, CDCl3): 1.07 (s, 84 H); 1.28 (s, 72 H); 1.3 0 (s, 72 H); 7.3 4 (d, J ˆ 1.8, 8 H); 7.40
(m, 16 H). 13C-NMR (125 MHz, CDCl3): 11.32; 18.67; 31.31; 34.78; 34.84; 81.29; 81.77; 85.97; 86.32; 86.64; 86.67;
101.93; 102.16; 102.50; 103.39; 114.50; 119.26; 121.23; 121.48; 122.36; 123.75; 124.02; 126.21; 126.52; 150.80;
‡
151.06. MALDI-TOF-MS: 2750 (100, M ).
4-{5-[4-(Dihexylamino)phenyl]-3-[10,19,24-tris(3-[4-(dihexylamino)phenyl]-1-{2-[4-(dihexylamino)phen-
yl]ethynyl}prop-2-yn-1-ylidene)-1,2,3,4,6,7,8,9,11,12,13,14,15,16,17,18,20,21,22,23,25,26,27,28-tetracosadehydro-
19,24-dihydrocyclohexadeca[a]cyclohexadecen-5(10H)-ylidene]penta-1,4-diyn-1-yl}-N,N-dihexylaniline (10).
To a cooled (08) soln. of 32 (37.9 mg, 0.011 mmol) in moist THF (20 ml), Bu4NF (0.1 ml of a 1.0m soln. in
THF, 0.1 mmol) was added. After stirring for 10 min, TLC control indicated complete desilylation. CH2Cl2
(30 ml) was added, and the soln. was filtered through a plug (SiO2; CH2Cl2). Evaporation in vacuo left a brown
oil that was redissolved in a mixture of THF, Me2CO, and PhH (150 ml, 1:1 :1). Hay catalyst (15 ml) was added,
and the mixture was stirred for 2 h at r.t. exposed to air. The deep-purple soln. was filtered through a plug (SiO2;
Me2CO) and evaporated in vacuo. FC (hexane/CH2Cl2 4 :1 ! 1 :1) gave 10 (4.6 mg, 16%). Deep-purple waxy
solid. UV/VIS (CHCl3): 306 (122600), 558 (176700), 591 (sh, 160200), 698 (85900). IR (CHCl3): 2957, 2930,
2858, 2159, 1601, 1522, 1265, 1188, 1129, 1085, 909. 1H-NMR (300 MHz, CDCl3): 0.86 (m, 48 H); 1.23( m, 48 H);
1.29 (m, 48 H); 1.51 (m, 32 H); 3.18 (t, J ˆ 8.0, 16 H); 3.26 (t, J ˆ 7.8, 16 H); 6.53( t, J ˆ 9.2, 16 H); 7.38 (d, J ˆ 9.2,
8 H); 7.3 9 (d, J ˆ 9.2, 8 H). 13C-NMR (125 MHz, CDCl3): 14.04; 22.670; 22.673; 26.75; 26.79; 27.22; 27.23; 31.64;
31.68; 50.98; 51.00; 84.32; 84.33; 86.69; 87.42; 87.56; 87.86; 92.27; 96.79; 104.65; 104.84; 107.55; 107.57; 109.76;
‡
111.21; 111.22; 116.38; 120.22; 133.95; 134.13; 148.90; 148.94. MALDI-TOF-MS: 2683.7 (100, M ).
5,10,19,24-Tetrakis(3-[3,5-di(tert-butyl)phenyl]-1-{2-[3,5-di(tert-butyl)phenyl]ethynyl}prop-2-yn-1-yli-
dene)-1,2,3,4,6,7,8,9,11,12,13,14,15,16,17,18,20,21,22,23,25,26,27,28-tetracosadehydro-5,10,19,24-tetrahydrocyclo-
hexadeca[a]cyclohexadecene (11). To a cooled (08) soln. of 33 (90 mg, 0.0328 mmol) in moist THF (20 ml),
Bu4NF (0.5 ml of a 1.0m soln. in THF, 0.5 mmol) was added. After stirring for 10 min, TLC control indicated
complete desilylation. CH2Cl2 (100 ml) was added, and the soln. was filtered through a plug (SiO2; CH2Cl2).
Evaporation in vacuo left a red oil that was redissolved in a mixture of THF, Me2CO, and PhH (450 ml, 1:1 :1).
Hay catalyst (25 ml) was added, and the mixture was stirred for 1 h at r.t. exposed to air. The deep-purple soln.
was filtered through a plug (SiO2; Me2CO) and evaporated in vacuo. The residue was subjected to FC (SiO2;
hexane/AcOEt 20 :1) to provide 11 (61.5 mg, 88%). Brown solid. UV/VIS (CHCl3): 408 (65400), 498 (122500),
595 (42300). IR (CHCl3): 3023, 2966, 2905, 2870, 2181, 1589, 1477, 1431.77, 1395, 1364, 1248, 879. 1H-NMR
(300 MHz, CDCl3): 1.25 (s, 72 H); 1.29 (s, 72 H); 7.3 6 d(, J ˆ 2.0, 16 H); 7.43( t, J ˆ 2.0, 8 H). 13C-NMR
(125 MHz, CDCl3): 31.29; 31.31; 34.82; 34.86; 84.14; 85.27; 86.01; 86.08; 87.03; 87.52; 90.85; 96.27; 103.25; 103.93;
114.61; 115.79; 120.82; 120.89; 121.47; 124.20; 124.37; 126.37; 126.42; 151.05; 151.06. MALDI-TOF-MS: 2115
‡
‡
‡
‡
(100, M ). FT-ICR-MALDI-MS: 2114 (100, M ). HR-FT-ICR-MALDI-MS: 2113.3166 (M , C162H168 ; calc.
2113.3146).
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Received October 21, 2003