Solid-Phase Synthesis of Oligo(triacetylene)s and Oligo(phenylenetriacetylene)s Employing Sonogashira and Cadiot-Chodkiewicz-Type Cross-Coupling Reactions

Article abstract of DOI:10.1002/hlca.200490066

We describe the first polymer-supported synthesis of poly(triacetylene)-derived monodisperse oligomers, utilizing Pd ⁰-catalyzed Sonogashira and Cadiot-Chodkiewicz-type cross-couplings as the key steps in the construction of the acetylenic scaf

Full text of DOI:10.1002/hlca.200490066

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Helvetica Chimica Acta Vol. 87 (2004)
Solid-Phase Synthesis of Oligo(triacetylene)s and
Oligo(phenylenetriacetylene)s Employing Sonogashira and
CadiotÀChodkiewicz-Type Cross-Coupling Reactions
by Nils F. Utesch and FranÁois Diederich*
Laboratorium f¸r Organische Chemie, ETH-Hˆnggerberg, HCI, CH-8093Z¸rich
and
Corinne Boudon, Jean-Paul Gisselbrecht, and Maurice Gross
¬
Laboratoire d×Electrochimie et de Chimie Physique du Corps Solide, Faculte Louis Pasteur and CNRS, UMR
no. 7512, 4, rue Blaise Pascal, F-67000 Strasbourg
We describe the first polymer-supported synthesis of poly(triacetylene)-derived monodisperse oligomers,
utilizing Pd0-catalyzed Sonogashira and CadiotÀChodkiewicz-type cross-couplings as the key steps in the
construction of the acetylenic scaffolds. For our investigations, Merrifield resin functionalized with a 1-(4-
iodoaryl)triazene linker was chosen as the polymeric support (R2; Figure and Scheme 3). The linker selection
was made based on the results of several model studies in the liquid phase (Schemes 1 and 2). For the solid-
support synthesis of the oligo(phenylene triacetylene)s 7b 7d, a set of only three reactions was required: i) Pd0-
catalyzed Sonogashira cross-coupling, ii) Me3SiÀalkyne deprotection by protodesilylation, and iii) cleavage of
the linker with liberation of the generated oligomers (Scheme 5). The longest-wavelength absorption maxima of
the oligo(phenylene triacetylene)s 7a 7d shift bathochromically with increasing oligomeric length, from lmax
337 nm (monomer 7a) to 384 nm (tetramer 7d; Table 2). Based on the electronic absorption data, the effective
conjugation length (ECL) of the oligo(phenylene triacetylene)s is estimated to involve at least four monomer
units and 40 C-atoms. p-Electron conjugation in these oligomers is less efficient than in the known
oligo(triacetylene)s 14a 14d (Table 2) due to poor transmittance of p-electron delocalization by the phenyl
rings inserted into the oligomeric backbone. Similar conclusions were drawn from the electrochemical
properties of the two oligomeric series as determined by cyclic (CV) and rotating-disk voltammetry (RDV;
Table 3). In sharp contrast to 14b 14d, the oligo(phenylene triacetylene)s 7b 7d are strongly fluorescent, with
the highest quantum yield FF ˆ 0.69 measured for trimer 7c (Table 2). Whereas the Sonogashira cross-coupling
on solid support proceeded smoothly, optimal conditions for alkyneÀalkyne cross-coupling reactions employing
Pd0-catalyzed CadiotÀChodkiewicz conditions still remain to be developed, despite extensive experimentation
(Scheme 7 and Table 1).
1. Introduction. Monodisperse linearly p-conjugated oligomers of precise length
and constitution have attracted considerable scientific interest. They have been
recognized as valuable model systems for the corresponding infinite polymers, and their
investigation has greatly benefitted the rational design of new functional polymers [1].
Furthermore, they have become integral to electronic and optical applications in
emerging technologies such as organic light-emitting diodes [2], organic semiconduc-
tors [3], and nanoscale as well as single-molecule-based molecular electronics [4].
To explore structureÀproperty relationships in oligo(triacetylene)s and extrapolate
the properties of long-chain poly(triacetylene)s (PTAs), we had prepared several series
of monodisperse PTA oligomers extending in length up to 17.8 nm (24-mer) by

Helvetica Chimica Acta Vol. 87 (2004)
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oxidative acetylenic coupling [5] of monomeric (E)-1,2-diethynylethene (DEE; (E)-
hex-3-ene-1,5-diyne; e.g., DEE derivative 1) or higher oligomers [6]. This approach
always generated oligomeric mixtures, and the separation and isolation of individual
oligomers, formed in low-to-moderate yield, required tedious gravity and high-
performance gel permeation chromatography (GPC).
Solid-phase synthesis could offer a more efficient approach towards tailor-made
PTA oligomers, potentially facilitating workup and purification protocols, and allowing
flexible control of the oligomeric length. With the extensive development of solid-
phase organic synthesis in the 1990s [7], monodisperse p-conjugated oligomers, in
particular oligothiophenes [8] and oligo(phenylene ethynylene)s [9], have indeed
increasingly been prepared on polymeric support, thereby overcoming the problems
associated with solution-phase synthesis. Here, we present the development of a solid-
phase synthesis on Merrifield resin (chloromethyl-substituted, 1% cross-linked poly-
(styrene divinylbenzene)) [10] for the construction of oligo(triacetylene)s and
oligo(phenylene triacetylene)s, a new class of linearly p-conjugated oligomers, by
means of Pd0-catalyzed cross-coupling reactions (for a preliminary communication of
parts of this work, see [11]).
2. Results and Discussion. 2.1. Evaluation of Suitable Linker Systems in Liquid-
Phase Studies. A prerequisite for a successful application of solid-support chemistry to
oligomer synthesis is the choice of an appropriate linker moiety to attach the starting
monomer onto the resin. 1-Aryltriazene linkers have been widely used in the
preparation of oligo(phenylene ethynylene)s as well as phenylacetylene-based
dendrimers [9]; they are compatible with Pd0-catalyzed coupling reactions and can
be cleaved from the resin under a variety of conditions [7c][9][12]. Thus, aromatic
diazonium salts are accessible by cleaving the triazene with trifluoroacetic acid (TFA)
[12b,c], whereas a cleavage utilizing MeI generates the corresponding aryl iodides
[7c][9][12f]. Traceless cleavage replacing the triazene substituent with a CÀH bond
can be achieved by either using 10% HCl in THF [12a], H3PO2 in Cl2CHCOOH [12a],
or HSiCl3 in CH2Cl2 [12e].
We opted for the two resin-linker conjugates R2 and R3, which were introduced by
Moore and co-workers [9a c] and differing only in the length of the spacer between
the triazene moiety and the resin. In a first step, we investigated their applicability to
the synthesis of oligo(triacetylene)s in liquid-phase test reactions by using the readily
available, soluble counterparts 2 and 3 (Figure).

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Figure. Merrifield resin-linker conjugates R2 and R3, and their soluble counterparts 2 and 3
Attachment of mono-deprotected DEE 4 [6a] to both linker systems 2 and 3 by
Sonogashira cross-coupling [13] proceeded smoothly, providing the DEE-linker
conjugates 5 and 6, respectively, in high yield (ca. 90%; Scheme 1). In contrast, 5 and
6 differed substantially in their reactivity during linker cleavage using MeI at 1108 for
6 h. (Benzyloxyethyl)triazene 5 was more reactive and provided aryl iodide 7a in 85%
yield, whereas cleavage of benzyl derivative 6 only proceeded in 66% yield,
demonstrating the steric advantage of the longer spacer connecting the triazene
moiety to the aryl ring in 2 (and to the Merrifield resin in R2; Figure). We also
examined the DEE-linker conjugate 6 under the conditions of traceless cleavage
(Scheme 1) [12a,e]. Unfortunately, all applied experimental conditions turned out to be
too acidic, and, in each experiment, diol 8 was obtained by cleavage of the O-protecting
silyl groups.
Protodesilylation of 5 and 6 with 2n NaOH in MeOH/THF provided the terminally
deprotected alkynes 9 and 10, respectively (Scheme 2). Besides unproblematic
Sonogashira cross-couplings with aryl halides [14], acetylenic hetero-couplings under
Hay [15] and Cadiot À Chodkiewicz-type conditions [16] were explored with the two
alkynes. In the latter conversion, the original protocol (CuCl, Et2NH, NH2OH ¥ HCl,
EtOH/H2O 95 :5) [16] was not used, since the Merrifield resin (in the subsequent solid-
supported reactions) swells poorly in alcoholic solutions [17]. To circumvent this
problem, we switched to the alternative Pd0-catalyzed alkyne cross-coupling in benzene
developed by Vasella and co-workers for the synthesis of acetylenosaccharides [18].
[(Benzyloxy)ethyl]triazene 9 was found superior in both the Hay coupling with 4 (4
equiv.) and the CadiotÀChodkiewicz-type coupling with bromoalkyne 11 (1 equiv.)
[19], providing 12 in 58 and 56% yield, respectively. The yields of 13 in the
corresponding coupling with benzyltriazene 10 were markedly lower (47 and 43%,
resp.). DEE Dimer 14b, resulting from oxidative homo-coupling of 4, was an important
side-product under the Hay-coupling conditions, but was also formed in small
quantities in the Pd0-catalyzed cross-coupling of 10 with 11.
Finally, the triazene linkers were cleaved with MeI at 1108 for 6 h to yield (4-
iodophenyl)-substituted DEE dimer 15. Again, the yield for cleavage of the
(benzyloxy)ethyl derivative 12 was much higher (60%) compared with only 21% for
benzyl derivative 13. The moderate cleavage yields for both linker systems are in

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Scheme 1. Liquid-Phase Test Reactions with Linkers 2 and 3
a) [Pd(PPh3)2Cl2], CuI, Et3N, 258, 20 h; 89% (5); 90% (6). b) MeI, 1108, 6 h; 85% (from 5); 66% (from 6). c) 1n
HCl/THF 1:10, ultrasound, 508, 10 min; 43%. d) H3PO2, Cl2CHCOOH, 258, 4 h; 37%. e) HSiCl3, CH2Cl2, 408,
15 min; 52%.
agreement with previous reports, which show that electron-withdrawing groups in the
para-position of the aromatic ring, such as the DEE dimer fragments in 12 and 13 [14b],
slow down the conversion to the aryl iodide [9f][20].
Clearly, the (benzyloxyethyl)triazene linker system with the longer spacer between
triazene moiety and aryl ring shows, certainly for steric reasons, substantial advantages
over the benzyltriazene analog in terms of alkyne coupling yields and cleavage
efficiency. Therefore, the resin-linker combination R2 (Figure) was used in the
development of a solid-phase synthesis of oligo(triacetylene)-derived oligomers.
2.2. Solid-Phase Synthesis of Oligo(phenylene Triacetylene)s by Sonogashira Cross-
Coupling. In a first step, polymer-supported triazene R2 was obtained by etherification
of Merrifield resin (0.9 mmol Cl/g resin) with (2-hydroxyethyl)triazene 16 with NaH in
THF [9b] (Scheme 3). Elemental analysis showed a resin loading of 0.57 mmol I/g
resin. Thus, a comparison of this value with the theoretical maximum loading of
0.72 mmol I/g resin provides a yield of 79% [9d] (see also Exper.Part ). The resin-
bound linker was subsequently coupled under Sonogashira conditions with DEE

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Scheme 2. Alkyne Coupling and Linker-Cleavage Test Reactions in the Liquid Phase
a) 2n NaOH, MeOH/THF 1:1, 258, 45 min; quant. b) CuCl, TMEDA, O2, CH2Cl2, 258, 3.5 h; 58% (12) and
27% (14b); 47% (13) and 50% (14b). c) [Pd2(dba)3], CuI, PMP, LiI, C6H6, 258, 7 h; 56% (12); 43% (13) and
17% (14b). d) MeI, 1208, 6 h; 60% (from 12); 21% (from 13). TMEDA ˆ N,N,N',N'-Tetramethylethylenedi-
amine; dba ˆ dibenzylideneacetone; PMP ˆ 1,2,2,6,6-pentamethylpiperidine.
monomer 4 (1.5 equiv.) to afford polymer-bound DEE 17 in 91% yield. Conditions
were chosen (see Exper.Part ) to minimize by rigorous degassing homo-coupling of
4, and to allow recovery and recycling of excess starting material. At the end of the
coupling reaction, resin-bound DEE 17 was isolated by filtration, washed, and dried in
vacuo. Treatment with MeI at 1208 for 24 h led to linker cleavage, providing
iodoarylated DEE 7a in a satisfying yield of 83% over three steps (including the
attachment of linker 16 to the Merrifield resin). Also, protodesilylation of 17 (2n
NaOH, MeOH/THF) proceeded smoothly, providing the terminally deprotected
alkyne 18 in quantitative yield. The progress of the deprotection was analyzed by
infrared (IR) spectroscopy, monitoring the disappearance of the band at 2133 cmÀ1
(CꢀCÀSiMe3 stretch) and the appearance of the bands at 3311 cmÀ1 (CꢀCÀH

Helvetica Chimica Acta Vol. 87 (2004)
Scheme 3. Synthesis of Resin-Bound DEE
703
a) NaH, THF, À788 ! 458, 5 d; 79%. b) 4, [Pd2(dba)3], CuI, PPh3, Et3N, 708, 24 h; 91%. c) MeI, 1208, 24 h; 83 %
(3steps). d) 2n NaOH, MeOH/THF 1:1, 708, 3h; quant. Yields are given starting from the attachment of 16 to
the Merrifield resin (see also the Exper.Part ).
stretch) and 2109 cmÀ1 (CꢀCÀH stretch). IR Analysis was also useful for monitoring
the progress of the subsequent cross-coupling reactions.
Initially, we wanted to build up oligo(phenylene triacetylene)s by mono-cross-
coupling of resin-bound DEE 18 to 1,4-diiodobenzene 19, followed by a repetitive
sequence of i) cross-coupling with DEE monomer 4, ii) alkyne desilylation, and iii)
mono-coupling to 19 (Scheme 4). Product analysis after each step would be done by
both elemental analysis and IR spectroscopy. Regrettably, substantial siteÀsite
interactions were already observed during the first coupling between 18 and 19 despite
using a large excess of 19 (5 equiv.). After executing the Sonogashira cross-coupling,
cleavage of the linker with MeI provided the desired bis(4-iodophenyl)-substituted
DEE 20 (19% over five steps) in addition to the bis-DEE derivative 21 (27% over five
steps). This undesired side-product is formed by the reaction of two adjacent resin-
bound DEEs 18 with 1 equiv. of diiodide 19. SiteÀsite interactions are of frequent
concern in solid-phase chemistry, even in highly cross-linked resins with low loading
levels [21]. The pseudo-dilution effect provided by the Merrifield support has been
shown to be rather limited, largely due to its conformational flexibility [22].
In view of the encountered siteÀsite interactions, the synthetic strategy was
changed to the successful one shown in Scheme 5. The oligo(phenylene triacetylene)s
7b 7d were prepared in a short period of time starting from 17 (Scheme 3) by
repetitive cycles of three conversions: i) deprotection of the resin-bound alkyne, ii)
Sonogashira cross-coupling with iodoarylated DEE 7a, and iii) liberation of the formed
oligomer from the solid support with MeI. The solvent mixture used in the cross-
coupling step was changed from Et3N to THF/Et2NH 4 :1 to take advantage of the
better swelling properties of Merrifield beads in THF [17].

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Scheme 4. SiteÀSite Interactions in the Sonogashira Cross-Coupling between Resin-Bound DEE 18 and 1,4-
Diiodobenzene (19)
a) [Pd2(dba)3], CuI, PPh3, Et3N, 708, 24 h. b) MeI, 1208, 24 h; 19% (20, 5 steps); 27% (21, 5 steps).
The oligomeric yields exhibited a significant dependence upon the iodine-loading
level s of resin R2. At a loading of 0.57 mmol/g resin, only dimer 7b was obtained in
good yield (63% over five steps), whereas trimer 7c was formed in only 10% yield (over
seven steps), and tetramer 7d could not be isolated at all (Scheme 5). Apparently, a
high concentration of reactive sites functionalized with the oligomers leads to
overcrowding of the resin pores, thereby preventing further conversions. The use of
solid support R2 containing a lower iodine-loading of 0.20 mmol/g resin, indeed,
provided significantly better results. Whereas monomer 7a (Scheme 3) was obtained in
identical yield at both resin loadings, the reduced loading substantially increased the
yield of dimer 7b (82% over five steps), trimer 7c (56% over seven steps), and tetramer
7d (36% over nine steps).
The oligo(phenylene triacetylene)s 7b 7d are yellow, air- and light-stable solids
that melt, apart from tetramer 7d, without decomposition. Solubility decreases rapidly
with increasing oligomeric length. Whereas monomer 7a and dimer 7b are soluble in all
common solvents, trimer 7c and especially tetramer 7d are only poorly soluble in
CH2Cl2.
Dimer 7b and tetramer 7d were also prepared by an iterative divergent/convergent
strategy (Scheme 6) utilizing a resin with an iodine-loading of 0.31 mmol/g resin. In
general, this binomial approach provides higher yields of longer oligomers due to the
reduction in the number of transformations [9b,c,d][23]. However, in this study, we
observed the opposite. Dimer 7b was formed in only 50% yield (over five steps), and

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Scheme 5. Solid-Phase Synthesis of Oligo(phenylene triacetylene)s 7b 7d
a) 2n NaOH, MeOH/THF 1 :1, 708, 3 h. b) 7a, [Pd2(dba)3], CuI, PPh3, Et2NH/THF 1:4, 708, 24 h. c) MeI, 1208,
24 h. Iodine loading sR2 in mmol/g resin.
tetramer 7d was obtained in just 19% yield (over seven steps), which is less than the
yields obtained in the stepwise synthesis (Scheme 5). We tentatively explain these
results that contrast some of those obtained by others on similar resins with similar
loadings [9a d][22][23a c] with the steric hindrance in the resin pores, caused by the
bulky (t-Bu)Me2SiOCH2 substituents on the oligomeric backbones, as well as the
limited solubility of the formed oligo(phenylene triacetylene)s.
2.3. Solid-Phase Synthesis of Oligo(triacetylene)s by CadiotÀChodkiewicz-Type
Cross-Coupling. In contrast to the large number of published Sonogashira cross-
coupling reactions on solid phase [1a][9][22][23a c], only one report has appeared on
solid-supported CadiotÀChodkiewicz couplings [24]. Following the test reactions in
solution (Scheme 2), we reacted resin-supported DEE 18 (iodine-loading of precursor
resin R2: s ˆ 0.20 mmol/g resin) with bromoderivative 11 under various conditions
(Table 1) in degassed benzene or THF at 458. After 20 24 h, IR analysis still showed
incomplete conversion. Cleavage of the linker with MeI at 1208 provided in each run a
mixture of three compounds, namely the desired hetero-coupled dimer 15, uncoupled
monomer 22, and homo-coupled dimer 23, resulting from siteÀsite interactions. While
rather unstable, oily 22 was readily isolated by chromatography (SiO2; hexanes/CH2Cl2
2 :1), separation of the two yellow, stable dimers 15 and 23 was unsuccessful, even by
preparative high-performance liquid chromatography (HPLC). The yields of the two
dimers, however, could be determined by analytical HPLC. For a complete character-

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Scheme 6. Binomial Synthesis of Oligo(phenylene Triacetylene)s
a) [Pd2(dba)3], CuI, PPh3, Et2NH/THF 1 :4, 708, 24 h. b) MeI, 1208, 24 h; 83 % (7a, 3steps); 50% ( 7b, 5 steps);
19% (7d, 7 steps). c) 2n NaOH, MeOH/THF 1:1, 708, 3 h.
ization, dimer 23 was independently prepared by oxidative Hay coupling of 22
(Scheme 7), obtained by deprotection of 7a.
The Pd0-catalyzed CadiotÀChodkiewicz coupling on solid support was investigated
in further detail (Table 1). Benzene was found to be superior to THF as the solvent,
providing slightly higher product yields and selectivities. Omitting CuI ions, while at the
same time raising the amount of Pd catalyst, leads to preferential formation of the
desired dimer 15 (Table 1, Entry 4 vs.1 ). The best result was obtained when,

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Scheme 7. CadiotÀChodkiewicz Cross-Coupling on Solid Support
a) [Pd2(dba)3], CuI, LiI, PMP, C6H6 or THF, 458, 20 24 h. b) MeI, 1208, 24 h (for yields, see Table 1). c) CuCl,
TMEDA, O2, CH2Cl2, 258, 12 h; 19%.
Table 1. Optimization of the Pd0-Catalyzed CadiotÀChodkiewicz Cross-Coupling on Solid Support. Solvent:
benzene.
Entry
Equiv. of 11
Equiv. of
[Pd2(dba)3]
Equiv. of
CuI
Yield [%]
22a)
15/23b)
1
2
3
4
5
6
1.5
1.5
1.5
1.5
5.0
5.0
0.030.02
27
16 :35
0.10
:278
21 : 4
0.03
0.20
0.20
0.03
0.20
5
8
20
27 : 13
36 : 8
23
2
37 : 10
a) Isolated yields. b) Determined by calibrated HPLC.
additionally, the amount of bromoderivative 11 was raised to 5 equiv. (Entry 6).
Nevertheless, the formation of the undesired, unseparable side-product 23 by homo-
coupling could never be completely suppressed. The occurrence of 23 at rather low
resin loading provides another example of the limited pseudo-dilution effect of
polymeric resins in solid-phase syntheses.
2.4. Optical Spectroscopy. The electronic absorption and emission spectra of the
new oligo(triacetylene)s 15, 20, and 23, and of oligo(phenylene triacetylene)s 7a 7d
and 21 in CHCl3 at room temperature are shown in Table 2 in comparison to the data
for the previously prepared oligo(triacetylene)s 14a 14d.
In the UV/VIS spectra, the following trends are observed: the longest-wavelength
absorption maxima lmax as well as the end-absorptions lend expectedly shift to lower
energies with increasing oligomer length. Thus, the end-absorptions in the spectra of
the oligo(phenylene triacetylene)s shift from 362 nm (monomer 7a), to 443nm (dimer
7b), and to 462 nm (tetramer 7d). With increasing oligomer length, the spectral fine-
structure is lost (for a spectral depiction, see [11]). The bathochromic shifts with
increasing conjugation length are less pronounced than in the series of oligo(triace-

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Table 2. UV/VIS and Fluorescence Data of the New Oligo(triacetylene)s 15, 20, and 23, and of Oligo(phenylene
Triacetylene)s 7a 7d and 21 in Comparison to the Known Oligo(triacetylene)s 14a 14d. Spectra recorded at
room temperature in CHCl3.
f
Compound
lmax/nma) [eV]
(e/mÀ1 cmÀ1)b)
lend/nmc)
lexc/nmd)
lem/nme)
FF
)
(e/mÀ1 cmÀ1)b)
20
15
23
7a
7b
7c
7d
21
363 [3.42] (sh, 23800)
391 [3.17] (sh, 27300)
408 [3.04] (sh, 37100)
337 [3.68] (41100)
360 [3.44] (54200)
381 [3.25] (97800)
384 [3.23] (122000)
372 [3.33] (60300)
296 [4.18] (sh, 19700)
376 [3.30] (sh, 24700)
407 [3.05] (sh, 36700)
439 [2.82] (sh, 56800)
405
441
451
362
443
457
462
441
322
415
449
494
350 (32000)
300 (26600)
350 (49300)
300 (34200)
350 (51000)
350 (75700)
350 (81100)
350 (51200)
388, 410
425, 448
439, 464
364
414, 439
436, 459
444, 475
425, 448
0.02
0.02
0.10
0.01
0.24
0.69
0.60
0.19
14ag)
14bg)
14cg)
14dg)
356 (25300)
356 (31800)
425
399, 440
0.01
0.01
a) Experimentally observed longest-wavelength absorption maxima. b) Molar extinction coefficient. c) Exper-
imentally observed wavelength at which the absorption reaches e ˆ 0 mÀ1 cmÀ1
.
d) Excitation wavelength.
e) Fluorescence emission band maximum. f) Fluorescence quantum yield: anthracene (FF ˆ 0.33 in hexane)
was used as reference compound [25]. g) Data taken from [6b,c].
tylene)s 14a 14d, since the phenyl rings in 7a 7d with their localized aromatic
resonance stabilization
are not as effective in propagating linear p-electron
delocalization. Nevertheless, saturation of the optical properties is not yet observed,
i.e., the effective conjugation length of oligo(phenylene triacetylene)s involves more
than 40 conjugated C-atoms. Substitution of terminal Me3Si groups by 4-iodoaryl
residues results in a bathochromic shift of the longest-wavelength absorption maxima
lmax [6e]. This is nicely illustrated by the comparison between the PTA dimers, bis-
Me3Si-end-capped 14b (376 nm), mono-iodoarylated 15 (391 nm), and bis(iodoary-
lated) 23 (408 nm).
In sharp contrast to poly(triacetylene) oligomers, the novel oligo(phenylene
triacetylene)s are strong emitters in CHCl3 at room temperature. Fluorescence
quantum yields FF were measured relative to anthracene in hexane solution (FF ˆ 0.33
[25]; Table 2). Whereas PTA dimer 14b and trimer 14c are only weakly fluorescent
(FF ˆ 0.01), and the tetramer 14d does not fluoresce at all, the oligo(phenylene
triacetylene)s 7b 7d are strong emitters with the highest quantum yield, FF ˆ 0.69,
being measured for trimer 7c. The weaker emitting properties of tetramer 7d cannot be
explained by chromophoric aggregation (as seen for oligo(phenylene ethynylene)s, see
[26]) since the LambertÀBeer law [27] is observed in the concentration range applied.
Rather, radiationless deactivation of the singlet excited state S1 could become more

Helvetica Chimica Acta Vol. 87 (2004)
709
important with increasing oligomeric length as a result of higher conformational
flexibility of the p-conjugated rod. The high fluorescence quantum yields of the
oligo(phenylene triacetylene)s 7b 7d are quite remarkable in view of their terminal
iodine substituents, which should promote intersystem crossing to the corresponding
triplet excited state T1.
2.5. Electrochemical Investigations. The redox characteristics of all new compounds
listed in Table 3 were studied by cyclic (CV) and rotating-disk voltammetry (RDV) in
CH2Cl2 (‡0.1m Bu4NPF6) at 208 with a classical three-electrode cell. The working
electrode was a glassy-C electrode (3mm in diameter), and the counter electrode was a
Pt wire. An Ag/AgCl electrode was used as reference electrode. All potentials are
‡
referred to the ferricinium/ferrocene (Fc /Fc) couple used as internal standard.
Table 3. Redox Characteristics of the New Oligo(phenylene Triacetylene)s 7a 7d and 21, and of Oligo(triace-
tylene)s 15, 20, and 23, Determined by Cyclic (CV) and Rotating-Disk Voltammetry (RDV) in CH2Cl2 at 208
a
Compound
CV
)
RDVb)
Epc [V]c)
Epa [V]c)
E
[V]
E
[V]
red
ox
1=2
1=2
(slope [mV]d))
(slope [mV]d))
e
7a
7b
À 2.35
À 2.17
À 2.32
À 2.12
À 2.20
‡ 1.25
‡ 1.15
À 2.34 (80)
À 2.17 (70)
)
)
e
7c
‡ 1.15
À 2.27 (140)
ca. ‡1.2
e
7d
20
‡ 1.30
‡ 1.21
)
)
e
e
À 2.24
À 2.39
À 2.13
À 2.29
À 2.07
À 2.32
À 2.07
À 2.30
)
e
e
21
15
23
‡ 1.16
‡ 1.24
‡ 1.30
)
)
e
À 2.12 (125)
)
e
e
‡ 1.23
)
)
a
‡
) Potentials vs. ferricinium/ferrocene (Fc /Fc), glassy C-electrode in CH2Cl2 ‡ 0.1m Bu4NPF6, scan rate n ˆ
b
0.1 V sÀ1
.
) Potentials vs. ferricinium/ferrocene (Fc /Fc), rotating disk-electrode in CH2Cl2 ‡ 0.1m Bu4NPF6.
‡
c) Peak potential Epc and Epa for irreversible reduction and oxidation, respectively. d) Logarithmic analysis of
the wave obtained by plotting E vs. log[(I/Ilim À I)]. e) Electrode inhibition.
In contrast to the oligo(triacetylene)s 14a 14d [6b,c], the new oligo(phenylene
triacetylene)s 7a 7d (as well as the other new chromophores 15, 20, 21, and 23)
displayed only irreversible electron transfers. Strong inhibition of the C-electrode
prevented the determination of their oxidation potentials by RDV, whereas the
reduction potentials were ascertained. The determination of the reduction potential of
tetramer 7d was impossible by both CVand RDV. Whereas the peak potentials Epa for
irreversible first oxidation in both oligomeric series are in the same range (7a 7d:
between 1.15 and 1.30 V; 14a 14d: between 1.23and 1.29 V [6b]), the anodic shift of
the reduction potentials upon increasing the oligomer length is much more pronounced
in the oligo(triacetylene)s (the reversible redox potential E'0 changes from À2.68 (14a)
to À1.80 V (14d)) than in the oligo(phenylene triacetylene)s (peak potential Epc
changes from À2.35 (7a) to À2.12 V (7c)). Although comparisons of irreversible

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Helvetica Chimica Acta Vol. 87 (2004)
peak potentials and reversible reduction potentials need to be taken with caution, the
results are in agreement with the UV/VIS data, which indicate that p-electron
delocalization in the oligo(triacetylene)s, facilitating electron uptake, is more effective
than in the oligo(phenylene triacetylene)s. At present, the reason for the irreversibility
of the electron transfers in the new oligomeric series is not clear.
3. Conclusions. We have described the preparation of the first monodisperse
oligo(phenylene triacetylene)s 7a 7d on solid phase by using a Merrifield resin with an
1-aryltriazene linker. The key step in the short synthesis involves the Pd0-catalyzed
Sonogashira cross-coupling, confirming previous work that this important C,C bond-
forming reaction proceeds smoothly on solid supports [9][12d f][22][23a c].
The novel oligo(phenylene triacetylene)s 7a 7d display interesting optical proper-
ties. Their longest-wavelength absorption maxima lmax expectedly shift bathochromi-
cally with increasing p-conjugation length although this shift is not as pronounced as in
the series of oligo(triacetylene)s 14a 14d, due to the reduced ability of the phenyl
rings to transmit p-electron delocalization along the oligomeric backbone. In sharp
contrast to 14b 14d, however, the new oligomers 7b 7d display strong fluorescence
with the highest quantum yield, FF ˆ 0.69, measured for trimer 7c. The preparation of
larger oligomers and related polymers will be further pursued with the objective to
explore potential electroluminescence applications.
Whereas the Sonogashira cross-coupling on solid support proceeded smoothly,
optimal conditions for polymer-supported CadiotÀChodkiewicz-type couplings still
remain to be found. One problem encountered in the entire study was the formation of
undesirable side products (such as 21 and 23) resulting from siteÀsite interactions. It is
clear that the pseudo-dilution effect is quite limited on Merrifield beads even at low
loadings, presumably due to the substantial conformational flexibility provided by this
support, as had already been pointed out in other studies [21][22].
We acknowledge the financial support by the Swiss National Science Foundation through the NCCR
−Nanoscale Science× and the ETH Research Council. We thank Prof. Dr. M.B.Nielsen (Odense) for helpful
discussions and Boris Thamberger for the preparation of starting materials.
Experimental Part
General. Reagents and solvents purchased were reagent grade and used as received. Compounds 4 [6a] and
11 [19] were synthesized according to literature procedures. CH2Cl2 was dried over CaH2, and PhMe and THF
over Na/benzophenone ketyl. All reactions, except Hay couplings, were carried out in oven-dried glassware
under Ar by applying a positive pressure of the protecting gas. For the Hay couplings, the following mixture was
used as −Hay catalyst×: CuCl (0.13g, 1.3mmol) and N,N,N ',N'-tetramethylethylenediamine (TMEDA; 0.16 g,
1.4 mmol) in CH2Cl2 (4.5 ml). Evaporations and concentrations in vacuo were carried out at H2O-aspirator
pressure. TLC: Macherey-Nagel ALUGRAM SIL G/UV254 plates. Column-chromatographic purification refers
to flash chromatography (FC) on silica gel 60 (230 400 mesh). Anal. HPLC: Merck-Hitachi Pump L-7100,
Merck-Hitachi Autosampler L-7200, Merck-Hitachi UV Detector L-7400, Merck-Hitachi Interface L-7000; all
separations were carried out at r.t. on a Knauer LiChrosorb 4.0-mm column at a flow rate of 1 ml minÀ1 and a
pressure of 35 bar. M.p.: B¸chi Melting Point B-450; uncorrected. UV/VIS Spectra (lmax [nm] (e [mÀ1 cmÀ1])):
Varian Cary-500 UV/VIS/NIR spectrophotometer, at r.t. Fluorescence spectra (lem [nm]): Spex FluoroLog-3.22
spectrophotometer, at r.t. Anthracene in hexane was used as reference compound in quantum-yield
determinations [25]. IR Spectra [cmÀ1]: Perkin-Elmer 1600 FT-IR, measured in KBr, CHCl3, CCl4, or as film.
1H- and 13C-NMR spectra [ppm]: Bruker AMX-500, Varian Gemini-200 and -300, at r.t. in CDCl3 or (CD3)2SO;
solvent peaks (CDCl3: 7.26 ppm for 1H and 77.0 ppm for 13C; (CD3)2SO: 2.05 ppm for 1H and 39.52 ppm for 13C)

Helvetica Chimica Acta Vol. 87 (2004)
711
as internal references. MS (m/z (%)). EI: VG Tribrid mass spectrometer at 70-eV ionization energy; MALDI-
TOF-MS: Bruker Reflex-MALDI-TOF (337-nm N2-laser system), 2,5-dihydroxybenzoic acid (DHB) as matrix;
HR-FT-ICR-MALDI-MS: Ion Spec Ultima FT-ICR-MS (337-nm N2-laser system), DHB and {(2E)-3-[4-(tert-
butyl)phenyl]-2-methylprop-2-enylidene}malononitrile (DCTB) as matrix. Elemental analyses were carried out
by the Mikroanalytisches Labor des Laboratoriums f¸r Organische Chemie at ETH Z¸rich.
Resin Loadings and Yields. In case of an easily detectable element present, the respective resin loadings
were determined by elemental analysis. Due to the polydispersity of Merrifield resin and the minor-weight
fractions of the resin-bound compounds compared to the overall material weight, the data obtained are only
approximated values. The following equation was used to determine the resin loadings: sx ˆ mx/Mx [mol/g], with
sx being the resin loading of the element X in mol/g and Mx being the molecular weight of the element X, while
mx corresponds to the weight fraction of X detected by elemental analysis. These resin loadings were compared
with the theoretical maximum loading s0: s0 ˆ N0/(1 ‡ N0 ¥ DM) [mol/g], with N0 being the molar amount of the
initial functionality per 1 g of resin and DM being the change in molecular weight of the resin-bound compound
by a reaction. The ratio between the experimentally obtained resin loading sx and the theoretical maximum
loading s0 provides the yield of a reaction on solid support.
Electrochemistry. CH2Cl2 purchased was from Merck, spectroscopic grade dried over molecular sieves
(4 ä), and stored under Ar prior to use. Bu4NPF6 was purchased electrochemical grade from Fluka and used as
received. The electrochemical experiments were carried out at 208 in 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 a Ag/AgCl 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. The electrochemical cell was connected to the
computerized multipurpose electrochemical device AUTOLAB (Eco Chemie BV, Utrecht, The Netherlands) by
the GPSE software running on a personal computer.
General Procedure 1 (GP 1) for Cleavage of Me3Si-Protecting Groups in Solution. To Me3Si-protected
alkyne (2 mmol) in MeOH/THF 1:1 (80 ml), 2n NaOH (2.5 ml) was added, and the mixture was stirred for ca.
15 min at r.t. (TLC control). After addition of sat. aq. NH4Cl soln. (120 ml), the two phases were separated, and
the aq. phase was extracted with CH2Cl2 (3 Â 120 ml), dried (MgSO4), and evaporated in vacuo. The products
were used without further purification.
General Procedure 2 (GP 2) for Sonogashira Cross-Couplings in Soln. An oven-dried Schlenk flask was
charged with the linker system 2 or 3 (1.0 equiv.), monomer 4 (1.1 equiv.), [Pd(PPh3)2Cl2] (5 mol-%), and Et3N
(20 ml/1 mmol linker), while Ar was flushed through the flask. After three freeze-pump-thaw cycles, the soln.
was frozen once again, and CuI (0.1 equiv.) was added while Ar was flushed through the flask. The flask was
evacuated and back-filled with Ar three times. The flask was sealed, and the mixture was allowed to warm up to
r.t. After stirring for 20 h, the resulting suspension was taken up in hexane and passed through a plug (SiO2-60;
hexane ! hexane/CH2Cl2 1:1) to remove residual catalyst. After evaporation in vacuo, the crude product was
purified by FC.
General Procedure 3 (GP 3) for the Cleavage of the Triazene Linker in Soln. An oven-dried, heavy-walled,
and screw-capped sealed tube was charged with the respective linker-alkyne conjugate and MeI (1 ml/0.1 mmol
triazene). After three freeze-pump-thaw cycles, the flask was back-filled with Ar, and the soln. was stirred for
6
18 h at 1108 1208. The resulting suspension was taken up in hexane and passed through a plug (SiO2-60;
hexane ! hexane/CH2Cl2 2 :1). After evaporation in vacuo, the crude product was purified by FC.
General Procedure 4 (GP 4) for Pd0-Catalyzed CadiotÀChodkiewicz Cross-Couplings in Soln. An oven-
dried Schlenk flask was charged with the linker-alkyne conjugate (1.0 equiv.), LiI (0.2 equiv.), 1,2,2,6,6-
pentamethylpiperidine (PMP; 2.8 equiv.), [Pd2(dba)3] (3mol-%), and C 6H6 (3ml/0.05 mmol alkyne). The
mixture was degassed by flushing Ar through the suspension for 10 min. CuI (2 mol-%) and 11 (1.0 equiv.) were
added successively, and the mixture was stirred for 7 h at r.t. The resulting suspension was taken up in hexane
and passed through a plug (SiO2-60; hexane ! hexane/CH2Cl2 1 :1) to remove residual catalyst. After
evaporation in vacuo, the crude product was purified by either FC or prep. TLC.
General Procedure 5 (GP 5) for the Sonogashira Cross-Coupling of 4 to the Solid Support. To an oven-
dried, heavy-walled flask with an Ar inlet, R2 (1.0 equiv.), 4 (1.5 2.0 equiv.), and Et3N or THF/Et2NH 4 :1
(2 ml/g resin) were added. This suspension was degassed by three freeze-pump-thaw cycles, and the flask was
back-filled with Ar. In a separate dry flask, a catalyst soln. consisting of [Pd2(dba)3] (2.5 mm), CuI (4.0 mm), and
PPh3 (20.0 mm) in Et3N or THF/Et2NH 4 :1 was degassed by three freeze-pump-thaw cycles and stirred at 708
for 2 h under Ar. The supernatant of this soln. (6 ml/g resin) was transferred via cannula to the flask containing

712
Helvetica Chimica Acta Vol. 87 (2004)
R2. This flask was sealed and kept for 24 h at 658 while agitating periodically. The resin was transferred to a
fritted filter with CH2Cl2, washed with CH2Cl2, DMF, a 0.05m soln. of sodium diethyl dithiocarbamate in DMF/
Et(i-Pr)2N 99 :1, DMF, CH2Cl2, and MeOH (30 ml/g resin each), and dried in vacuo to constant mass.
General Procedure 6 (GP 6) for Cleavage of Me3Si Protecting Groups on Solid Support. A suspension of
polymer-bound Me3Si-protected alkyne in MeOH/THF 1:1 (25 ml/g resin) and 2n NaOH (1 ml/g resin) was
heated under gentle stirring to 708 for 3h. The resin was transferred to a fritted filter, washed sequentially with
MeOH, H2O, MeOH, CH2Cl2, DMF, CH2Cl2, and MeOH (30 ml/g resin each), and dried in vacuo.
General Procedure 7 (GP 7) for Oligomeric Extension by Sonogashira Cross-Couplings on Solid Support.
To an oven-dried, heavy-walled flask with an Ar inlet, polymer-bound deprotected alkyne (1.0 equiv.), 4-
iodoarylated DEE 7a (2.0 equiv.), and Et3N or THF/Et2NH 4 :1 (2 ml/g resin) were added. This suspension was
degassed by three freeze-pump-thaw cycles, and the flask was back-filled with Ar. In a separate dry flask, a
catalyst soln. consisting of [Pd2(dba)3] (2.5 mm), CuI (4.0 mm), and Ph3P (20.0 mm) in Et3N or THF/Et2NH 4 :1
was degassed by three freeze-pump-thaw cycles and stirred at 708 for 2 h under Ar. The supernatant of this soln.
was transferred via cannula to the flask containing the polymer-bound deprotected alkyne (6 ml/g resin). This
flask was sealed and kept for 24 h at 658 while agitating periodically. The resin was transferred to a fritted filter
with CH2Cl2, washed with CH2Cl2, DMF, a 0.05m soln. of sodium diethyl dithiocarbamate in DMF/Et(i-Pr)2N
99 :1, DMF, CH2Cl2, and MeOH (30 ml/g resin each), and dried in vacuo to constant mass.
General Procedure 8 (GP 8) for Pd0-Catalyzed CadiotÀChodkiewicz Cross-Couplings on Solid Support.
An oven-dried, heavy-walled flask with an Ar inlet was charged with resin-bound alkyne (1.0 equiv.), LiI
(0.2 equiv.), PMP (2.8 equiv.), and benzene (18 ml/g resin). The suspension was degassed by three freeze-pump-
thaw cycles and warmed up to r.t. [Pd2(dba)3] (3mol-%) was added while Ar was flushed through the
suspension. Finally, CuI (2 mol-%) and a degassed soln. of 11 (1.5 5 equiv.) were added. The flask was sealed
and shaken for 20 24 h at 458. The suspension was taken up in CH2Cl2, transferred to a fritted filter, and washed
with CH2Cl2 (30 ml/g resin). Excess 11 can be recovered from the first CH2Cl2 wash. The resin was washed
sequentially with DMF, 0.05m soln. of sodium diethyl dithiocarbamate in DMF/Et(i-Pr)2N 99 :1, DMF, CH2Cl2,
and MeOH (30 ml/g resin each), and dried in vacuo to constant mass.
General Procedure 9 (GP 9) for the Cleavage of the Triazene Linkage on Solid Support. To an oven-dried,
heavy-walled flask with an Ar inlet, the respective polymer-supported oligomer and MeI (8 ml/g resin) were
added. The suspension was degassed by three freeze-pump-thaw cycles, and the flask was back-filled with Ar
and sealed. The suspension was stirred for 24 h at 110 1208. After removal of MeI in vacuo, the resin was
transferred to a fritted filter with CH2Cl2, and the product was extracted from the resin with hot CH2Cl2. The
resulting soln. was cooled to r.t. and filtered through a plug of SiO2. After evaporation in vacuo, the crude
product was purified by FC.
1-(4-Iodophenyl)-3-(2-hydroxyethyl)-3-ethyltriazene (16). To a suspension of 2-(ethylamino)ethanol
(1.66 ml, 17.0 mmol), K2CO3 (9.396 g, 68.0 mmol), and DMF (50 ml) at 08, 4-iodophenyldiazonium tetrafluoro-
borate [28] (5.402 g, 17.0 mmol) was added in portions over 1 h. After addition of H2O (100 ml), the mixture was
extracted with CH2Cl2 (150 ml). The org. phase was washed with H2O (1.5 l) and sat. aq. LiCl soln. (500 ml),
dried (MgSO4), and evaporated in vacuo to give 16 (4.888 g, 92%). Red oil. FT-IR (CHCl3): 3011m, 2977w,
2878w, 1433s, 1390s, 1338s, 1239m, 1224s, 1158m, 1046m, 1002m, 825m. 1H-NMR (200 MHz, CDCl3): 1.24 (t, J ˆ
7.0, 3H); 2.00 ( s, 1 H); 3.70 3.85 (m, 6 H); 7.14 (d, J ˆ 8.4, 2 H); 7.60 (d, J ˆ 8.4, 2 H). 13C-NMR (50 MHz,
‡
CDCl3): 13.4; 52.5; 60.9; 89.5; 122.2; 137.6; 149.6. FT-ICR-MALDI-MS (DHB, two-layer): 319.0131(3, M ,
‡
‡
‡
C10H14IN3O ; calc. 319.0182), 318.0095 (31, [M À H] ), 299.9987 (100, [M À H À H2O] ). Anal. calc. for
C10H14IN3O (319.15): C 37.63, H 4.42, N 13.17; found: C 37.80, H 4.38, N 12.97.
1-(4-Iodophenyl)-3-[2-(benzyloxy)ethyl]-3-ethyltriazene (2). To a soln. of PhCH2Br (0.855 g, 5.0 mmol) and
16 (1.595 g, 5.0 mmol) in dry THF (100 ml) at À508, NaH (0.400 g, 10.0 mmol) was added under Ar. The soln.
was warmed to r.t., then heated to reflux for 6 h. After addition of H2O (100 ml), the mixture was extracted with
CH2Cl2 (3 Â 70 ml). The combined org. phases were dried (MgSO4) and evaporated in vacuo. FC (SiO2-60;
hexane/CH2Cl2 4 :1) gave 2 (1.625 g, 79%). Yellow oil. FT-IR (film): 3022m, 2978m, 2931s, 2855s, 1472s, 1427s,
1389s, 1344s, 1239s, 1193m, 1161m, 1093s, 1001m, 825m. 1H-NMR (300 MHz, CDCl3): 1.33 (t, J ˆ 6.9, 3H); 3.79
(t, J ˆ 5.7, 2 H); 3.89 (q, J ˆ 6.9, 2 H); 3.99 (t, J ˆ 5.7, 2 H); 4.59 (s, 2 H); 7.25 (d, J ˆ 8.7, 2 H); 7.30 7.45 (m, 5 H);
7.68 (d, J ˆ 8.7, 2 H). 13C-NMR (50 MHz, CDCl3): 14.0; 46.7; 50.0; 67.2; 73.0; 89.2; 122.5; 127.5; 127.6; 128.4;
‡
‡
137.6; 138.0; 150.6. FT-ICR-MALDI-MS (DHB, two-layer): 409.0610 (19, M , C17H20IN3O ; calc. 409.0651),
408.0571 (100, [M À H] ).
‡
3-[2-(Benzyloxy)ethyl]-1-[4-((E)-3,4-bis{[(tert-butyl)dimethylsilyloxy]methyl}-6-(trimethylsilyl)hex-3-
ene-1,5-diyne-1-yl)phenyl]-3-ethyltriazene (5). The following compounds were reacted according to the GP 2: 2
(0.425 g, 1.04 mmol), 4 (0.500 g, 1.15 mmol), [Pd(PPh3)2Cl2] (0.036 g, 0.052 mmol, 5.0 mol-%), CuI (0.020 g,

Helvetica Chimica Acta Vol. 87 (2004)
713
0.104 mmol), and Et3N (20 ml). FC (SiO2-60; hexane/CH2Cl2 1:1 ! hexane/AcOEt 10 :1 ! hexane/AcOEt
5 :1) afforded 5 (0.665 g, 89%). Red oil. FT-IR (film): 2951s, 2929s, 2856s, 2133w, 1494w, 1462m, 1428m, 1394m,
1344m, 1251s, 1097s, 93 1w, 840s. 1H-NMR (200 MHz, CDCl3): 0.13( s, 12 H); 0.26 (s, 9 H); 0.98 (s, 18 H); 1.3 1 (t,
J ˆ 7.0, 3H); 3.77 ( t, J ˆ 5.8, 2 H); 3.88 (q, J ˆ 7.2, 2 H); 3.98 (t, J ˆ 5.4, 2 H); 4.56 (s, 2 H); 4.58 (s, 2 H); 4.59 (s,
2 H); 7.25 7.50 (m, 9 H). 13C-NMR (50 MHz, CDCl3): À5.1; À0.1; 11.4; 18.4; 25.8; 63.9; 64.2; 73.2; 81.4; 86.6;
102.1; 102.2; 106.4; 119.7; 120.5; 127.6; 127.7; 128.4; 128.7; 131.1; 132.1; 138.0; 150.9. FT-ICR-MALDI-MS (DHB,
‡
‡
‡
two-layer): 717.4117 (13, M , C40H63N3O3Si3 ; calc. 717.4177), 608.3524 (100, [M À BnOH À H] ). Anal. calc. for
C40H63N3O3Si3 (717.22): C 66.89, H 8.84, N 5.85; found: C 66.94, H 8.67, N 5.60.
3-[2-(Benzyloxy)ethyl]-1-{4-[(E)-3,4-bis{[(tert-butyl)dimethylsilyloxy]methyl}hex-3-ene-1,5-diyn-1-yl]-
phenyl}-3-ethyltriazene (9). The following compounds were reacted according to the GP 1: 5 (0.048 g,
0.067 mmol), THF (10 ml), MeOH (10 ml), and 2N NaOH (0.5 ml). Workup provided 9 (0.043g, 100%).
Yellow oil. FT-IR (CHCl3): 3312m, 3289w, 3054s, 2930m, 2856m, 2188w, 1461w, 1422w, 1394w, 1343w, 1256s,
1096m, 841m. 1H-NMR (300 MHz, CDCl3): 0.13( s, 12 H); 0.94 (s, 18 H); 1.29 (t, J ˆ 7.2, 3H); 3.54 ( s, 1 H); 3 .75
(t, J ˆ 5.7, 2 H); 3.86 (q, J ˆ 7.2, 2 H); 3.96 (t, J ˆ 5.4, 2 H); 4.54 (s, 2 H); 4.55 (s, 2 H); 4.56 (s, 2 H); 7.25 7.45 (m,
9 H). 13C-NMR (75 MHz, CDCl3): À5.3; 18.3; 25.7; 63.9; 64.0; 73.2; 81.1; 86.2; 88.3, 102.1; 115.0; 119.5; 120.5;
‡
127.5; 127.6; 127.8; 128.4; 132.1; 132.4; 139.3; 151.1. FT-ICR-MALDI-MS (DHB, two-layer): 646.3754 (2, M ,
‡
‡
C37H55N3O3Si2 , calc. 646.0300), 536.3134 (100, [M À BnOH À 2 H] ).
3-[2-(Benzyloxy)ethyl]-3-ethyl-1-{4-[(E,E)-3,4,9,10-tetrakis{[(tert-butyl)dimethylsilyloxy]methyl}-12-(tri-
methylsilyl)dodeca- 3,9-diene-1,5,7,11-tetrayn-1-yl]phenyl}triazene (12). The following compounds were reacted
according to GP 4: 9 (0.036 g, 0.050 mmol), 11 (0.025 g, 0.050 mmol), [Pd2(dba)3] (0.0012 g, 0.0014 mmol,
2.8 mol-%), CuI (0.00025 g, 0.0012 mmol), PMP (0.023ml, 0.126 mmol), LiI (0.0012 g, 0.009 mmol), and
benzene (3ml). Prep. TLC (SiO 2; hexane/CH2Cl2 1 :1) afforded 12 (0.030 g, 56%). Red-brown oil. FT-IR
1
(CHCl3): 2956s, 2856s, 2367w, 2133w, 1472m, 1433m, 1389m, 1344m, 1252m, 1100s, 83 9s. H-NMR (300 MHz,
CDCl3): 0.11 (s, 12 H); 0.13( s, 12 H); 0.21 (s, 9 H); 0.93( s, 36 H); 1.28 (t, J ˆ 7.2, 3H); 3.75 ( t, J ˆ 5.7, 2 H); 3.86
(q, J ˆ 7.2, 2 H); 3.96 (t, J ˆ 5.4, 2 H); 4.44, (s, 2 H); 4.49 (s, 2 H); 4.54 (s, 2 H); 4.55 (s, 2 H); 4.58 (s, 2 H); 7.25
7.45 (m, 9 H). 13C-NMR (75 MHz, CDCl3): À5.3; À0.3; 10.8; 18.3; 25.8; 63.9; 64.2; 68.1; 73.2; 81.9; 82.6; 85.1;
85.7; 86.9; 101.6; 104.2, 109.2; 119.4; 120.6; 127.6; 127.7; 128.5; 128.9; 129.7; 132.3; 133.1; 133.9; 138.1; 151.3. FT-
‡
‡
ICR-MALDI-MS (DHB, two-layer): 1102.6140 (39, [M ‡ Na] , C60H97N3NaO5Si5 ; calc. 1102.6172), 1079.6144
‡
‡
‡
(41, M ; C60H97N3O5Si5 ; calc. 1079.6275), 897.4910 (100, [M À BnOH À 2 H] ).
3-Benzyl-1-(4-iodophenyl)-3-propyltriazene (3). To suspension of PhCH2NH(Pr) [29] (2.237 g,
a
15.0 mmol), K2CO3 (8.291 g, 60.0 mmol), and DMF (100 ml) at 08, 4-iodophenyldiazonium tetrafluoroborate
[28] (4.639 g, 14.6 mmol) was added in portions over 1 h. After addition of H2O (200 ml), the mixture was
extracted with CH2Cl2 (200 ml). The org. phase was washed with H2O (2 l) and sat. aq. LiCl soln. (500 ml), dried
(MgSO4), and evaporated in vacuo. FC (SiO2-60; hexane/CH2Cl2 2 :1) afforded 3 (4.595 g, 81%). Red oil. FT-IR
(film): 3028m, 2965s, 2873m, 2367w, 1894w, 1677w, 1600w, 1495m, 1478s, 1450s, 1388s, 1344s, 1172s, 1150s, 1094s.
1H-NMR (200 MHz, CDCl3): 1.04 (t, J ˆ 7.6, 3H); 1.80 (− q×, J ˆ 7.6, 2 H); 3.77 (t, J ˆ 7.6, 2 H); 5.07 (s, 2 H); 7.41
(m, 5 H); 7.78 (br. s, 2 H); 7.81 (br. s, 2 H). 13C-NMR (50 MHz, CDCl3): 11.3; 21.6; 49.3; 55.7; 89.4; 122.5; 127.3;
‡
‡
127.8, 128.4; 136.5; 137.6; 150.3. FT-ICR-MALDI-MS (DHB, two-layer): 379.0447 (17, M , C16H18IN3 ; calc.
‡
‡
‡
379.0545), 378.0414 (100, [M À H] ), 364.2017 (11, [M À Me] ), 252.1477 (3, [M À I] ). Anal. calc. for
C16H18IN3 (379.08): C 50.67, H 4.78, N 11.08; found: C 50.85, H 4.90, N 10.92.
3-Benzyl-1-[4-((E)-3,4-bis{[(tert-butyl)dimethylsilyloxy]methyl}-6-(trimethylsilyl)hex-3-ene-1,5-diyn-1-yl)-
phenyl]-3-propyltriazene (6). The following compounds were reacted according to GP 2: 3 (0.394 g, 1.04 mmol),
4 (0.500 g, 1.15 mmol), [Pd(PPh3)2Cl2] (0.036 g, 0.052 mmol, 5.0 mol-%), CuI (0.020 g, 0.104 mmol), and Et3N
(6 ml). FC (SiO2-60; hexane/CH2Cl2 2 :1) afforded 6 (0.658 g, 90%). Red oil. FT-IR (film): 2963s, 2918s, 2823s,
2133m, 1494m, 1448m, 1400m, 1361m, 1251m, 1097m, 93 1w, 83 9s. 1H-NMR (200 MHz, CDCl3): 0.16 (s, 12 H);
0.26 (s, 9 H); 0.94 (t, J ˆ 6.6, 3H); 0.97 ( s, 18 H); 1.69 (−q×, J ˆ 6.6, 2 H); 3.68 (t, J ˆ 6.6, 2 H); 4.58 (br. s, 4 H);
4.99 (s, 2 H); 7.3 3 m( , 5 H); 7.47 (m, 4 H). 13C-NMR (50 MHz, CDCl3): À5.1; À0.1; 11.4; 18.4; 25.8; 63.8; 64.1;
86.6; 102.0; 102.1; 106.4; 119.7; 120.5; 127.4; 127.9; 128.5; 131.0; 132.1; 136.8; 150.7. MALDI-TOF-MS (DCTB):
‡
‡
688.4 ([M ‡ H] ), 631.3 ([M À t-Bu] ). Anal. calc. for C39H61N3O2Si3 (688.19): C 68.07, H 8.93, N 6.11; found:
C 68.67, H 8.46, N 6.04.
(E)-3,4-Bis{[(tert-butyl)dimethylsilyl)oxy]methyl}-1-(4-iodophenyl)-6-(trimethylsilyl)hex-3-ene-1,5-diyne
(7a). The following compounds were reacted according to GP 3: 6 (0.097 g, 0.146 mmol) and MeI (1.5 ml). FC
(SiO2-60; hexane/CH2Cl2 2 :1) afforded 7a (0.062 g, 66%). Colorless solid. M.p. 518. UV/VIS (CHCl3): 253
(14100), 317 (47800), 337 (41100). FT-IR (CHCl3): 3013m, 2957m, 2924m, 2857m, 2135w, 1599w, 1499w, 1489w,
1388w, 1252m, 1222s. 1H-NMR (300 MHz, CDCl3): 0.11 (s, 12 H); 0.22 (s, 9 H); 0.93( s, 18 H); 4.49 (s, 2 H); 4.54
(s, 2 H); 7.15 (d, J ˆ 8.4, 2 H); 7.72 (d, J ˆ 8.4, 2 H). 13C-NMR (75 MHz, CDCl3): À5.3; À0.3; 18.2; 25.8; 63.9;

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Helvetica Chimica Acta Vol. 87 (2004)
64.0; 88.0; 94.5; 100.1; 101.8; 107.2; 122.8; 129.9; 130.5; 132.9; 137.6. FT-ICR-MALDI-MS (DHB, two-layer):
‡
‡
‡
‡
661.1825 (24, [M ‡ Na] ; C29H47INaO2Si3 ; calc. 661.1826), 638.1867 (46, M , C29H47IO2Si3 ; calc. 638.1928),
‡
‡
637.1841 (100, [M À H] ), 581.1235 (29, [M À t-Bu] ). Anal. calc. for C29H47IO2Si3 (638.85): C 54.52, H 7.42;
found: C 55.07, H 7.80.
(E)-2-(Phenylethynyl)-3-[(trimethylsilyl)ethynyl]but-2-ene-1,4-diol (8). To a soln. of 6 (0.10 g, 0.15 mmol)
in CH2Cl2 (40 ml) at r.t., HSiCl3 (15 ml, 0.15 mmol) was added. After stirring for 15 min, SiO2 (0.15 g) was added,
and the resulting suspension was filtered. The filtrate was evaporated in vacuo, and FC (SiO2-60; hexane/AcOEt
5 :2) afforded 8 (0.022 g, 52%). Yellow solid. 1H-NMR (300 MHz, CDCl3): 0.24 (s, 9 H); 1.85 1.95 (2 H); 4.47
‡
(s, 2 H); 4.49 (s, 2 H); 7.3 7.5 ( m, 5 H). EI-MS: 284.1 (M ).
3-Benzyl-1-[4-((E)-3,4-bis{[(tert-butyl)dimethylsilyloxy]methyl}hex-3-ene-1,5-diyn-1-yl)phenyl]-3-propyl-
triazene (10). The following compounds were reacted according to GP 1: 6 (0.10 g, 0.146 mmol), THF (10 ml),
MeOH (10 ml), and 2n NaOH (1 ml). After workup, 10 (0.087 g, 97%) was obtained as a red-brown oil. FT-IR
(CHCl3): 3300m, 2928s, 2845s, 2189w, 1600w, 1494m, 1448s, 1400s, 1355s, 1250s, 1094s, 83 9s, 778s. 1H-NMR
(200 MHz, CDCl3): 0.15 (s, 12 H); 0.89 (t, J ˆ 7.0, 3H); 0.96 ( s, 18 H); 1.69 (−q×, J ˆ 7.0, 2 H); 3.56 (s, 1 H); 3 .68 (t,
J ˆ 7.0, 2 H); 4.58 (br. s, 4 H); 4.99 (s, 2 H); 7.3 0 (m, 5 H); 7.45 (m, 4 H). 13C-NMR (50 MHz, CDCl3): À5.0;
11.4; 18.4; 25.9; 64.0; 64.1; 80.9; 86.3; 88.3; 102.0; 119.7; 120.6; 127.6; 128.0; 128.6; 131.9; 132.2; 150.9. FT-ICR-
‡
‡
MALDI-MS (DHB, two-layer): 614.3619 (39, [M À H] , C36H52N3O2Si2 ; calc. 614.3598), 569.2479 (7, [M À H À
‡
‡
3Me] ); 481.2674 (100, [M À 3 H À OSi(t-Bu)Me2] ).
3-Benzyl-3-propyl-1-[4-((E,E)-3,4,9,10-tetrakis{[(tert-butyl)dimethylsilyloxy]methyl}-12-(trimethylsilyl)-
dodeca-3,9-diene-1,5,7,11-tetrayn-1-yl)phenyl]triazene (13). The following compounds were reacted according
to GP 4: 10 (0.034 g, 0.055 mmol), 11 (0.028 g, 0.055 mmol), [Pd2(dba)3] (0.0014 g, 0.0017 mmol, 3.1 mol-%),
CuI (0.00025 g, 0.0012 mmol), PMP (0.023ml, 0.126 mmol), LiI (0.0012 g, 0.009 mmol), and C 6H6 (3ml). Prep.
TLC (SiO2; hexane/CH2Cl2 1:1) afforded 13 (0.020 g, 43%) and 14b (4 mg, 17%) [6b]. Red-brown, viscous oil.
FT-IR (CHCl3): 3677w, 3611w, 3011s, 2389m, 2134w, 1517m, 1416m, 1228s, 1200s, 1044m, 794s. 1H-NMR
(300 MHz, CDCl3): 0.11 (s, 12 H); 0.12 (s, 12 H); 0.21 (s, 9 H); 0.92 (s, Me); 0.93( s, 36 H); 1.67 (−q×, J ˆ 7.0, 2 H);
3.66 (t, J ˆ 7.0, 2 H); 4.43(br. s, 2 H); 4.49 (br. s, 2 H); 4.53(br. s, 2 H); 4.58 (br. s, 2 H); 4.98 (s, 2 H); 7.20 7.40
(m, 5 H); 7.43( m, 4 H). 13C-NMR (75 MHz, CDCl3): À5.1; À0.2; 11.4; 18.4; 25.9; 63.9; 64.1; 64.2; 81.9; 82.6;
85.1; 85.7; 86.9; 88.3; 101.6; 104.2; 119.5; 120.7; 127.7; 128.0; 128.6; 129.7; 130.9; 132.2; 132.3; 133.1; 133.8; 151.1.
‡
‡
FT-ICR-MALDI-MS (DHB, two-layer): 1072.6055 ([M ‡ Na] , C59H95N3NaO4Si5 ; calc. 1072.6068). Anal. calc.
for C59H95N3O4Si5 (1050.85): C 67.44, H 9.11, N 4.00; found: C 67.48, H 9.13, N 3.73.
(E,E)-1-(4-Iodophenyl)-3,4,9,10-tetrakis{[(tert-butyl)dimethylsilyloxy]methyl}-12-(trimethylsilyl)dodeca-
3,9-diene-1,5,7,11-tetrayne (15). The following compounds were reacted according to GP 3: 13 (0.010 g,
0.0097 mmol) and MeI (1 ml). FC (SiO2-60; hexane/CH2Cl2 1 :1) afforded 15 (0.006 g, 21%). Yellow solid. Mp
628. UV/VIS (CHCl3): 260 (30500), 287 (29000), 303 (33100), 324 (33300), 367 (46700), 391 (sh, 33200). FT-IR
(CHCl3): 2955s, 2929s, 2911m, 2856s, 2381w, 2133w, 1475m, 1389w, 1361w, 1252s, 1104s, 83 s8. 1H-NMR
(300 MHz, CDCl3): 0.08 0.12 (br. s, 24 H); 0.21 (s, 9 H); 0.92 (s, 36 H); 4.43 (br. s, 2 H); 4.48 (br. s, 2 H); 4.51
(br. s, 2 H); 4.53(br. s, 2 H); 7.16 (d, J ˆ 8.4, 2 H); 7.69 (d, J ˆ 8.4, 2 H). 13C-NMR (75 MHz, CDCl3): À5.1;
À0.2; 18.4; 25.9; 63.9; 64.1; 82.3; 82.6; 85.6; 85.7; 88.3; 94.8; 101.7; 102.0; 102.2; 122.5; 128.9; 129.0; 129.7; 133.0;
‡
‡
133.3; 133.5; 137.8. FT-ICR-MALDI-MS (DHB, two-layer): 1023.3815 (100, [M ‡ Na] , C49H81INaO4Si5 ; calc.
‡
1023.3924), 897.4863 (13, [M À OSi(t-Bu)Me2] ). Anal. calc. for C49H81IO4Si5 (1001.51): C 58.77, H 8.15; found:
C 59.13, H 7.75.
Resin-Bound 3-Ethyl-3-(2-hydroxyethyl)-1-(4-iodophenyl)triazene (R2). A Schlenk flask was charged with
Merrifield resin (1.684 g, 1.57 mmol Cl) and three times evacuated and back-filled with Ar. A soln. of 16 (2.50 g,
7.80 mmol) in dry THF (20 ml) was transferred via cannula onto the Merrifield resin under Ar. The mixture was
cooled to À788, and NaH (0.186 g, 4.65 mmol) was added in portions under a Ar blanket. After complete
addition, the mixture was warmed first to r.t., then heated to 458. After 5 d, the mixture was cooled, and MeOH/
H2O 1:1 (10 ml) was added. The polymer was isolated by filtration, washed with CH2Cl2, H2O, MeOH, AcOEt,
hexane, CH2Cl2, and MeOH (3 Â 100 ml of each), and dried in vacuo to a constant mass of 1.79 g. An elemental
analysis revealed an iodide loading of 0.57 mmol/g (79%). FT-IR (CCl4): 3062s, 3029s, 2928s, 2852s, 1942w,
1871w, 1803w, 1602s, 1493s, 1454s, 1369m, 1344m, 1327m, 1179m, 1091m, 1028m, 906w. Gel-phase 13C-NMR
(75 MHz, CDCl3): 14.4; 22.8; 31.7; 40.5; 42.0; 42.7; 44.0; 45.5; 46.0; 73.2; 89.3; 122.5, 127.9; 137.7; 145.3; 150.5.
Resin-Bound 1-[4-((E)-3,4-Bis{[(tert-butyl)dimethylsilyloxy]methyl}-6-(trimethylsilyl)hex-3-ene-1,5-diyn-
1-yl)phenyl]-3-ethyl-3-(2-hydroxyethyl)triazene (17). The following compounds were reacted according to
GP 5: R2 (0.500 g, 0.29 mmol), 4 (0.308 g, 0.60 mmol), [Pd2(dba)3] (0.011 g, 0.012 mmol, 4.1 mol-%), CuI
(0.0036 g, 0.019 mmol), PPh3 (0.025 g, 0.095 mmol), and Et3N (6 ml). After workup, the polymer was dried in

Helvetica Chimica Acta Vol. 87 (2004)
715
vacuo to a constant mass of 0.516 g (91%). FT-IR (CCl4): 3067w, 3022m, 2927s, 2855m, 2367w, 2133w, 1452s,
1390m, 1344m, 1092m, 1033w, 928w.
Resin-Bound 1-[4-((E)-3,4-Bis{[(tert-butyl)dimethylsilyloxy]methyl}hex-3-ene-1,5-diyn-1-yl)-phenyl]-3-
ethyl-3-(2-hydroxyethyl)triazene (18). The following compounds were reacted according to GP 6: 17 (0.300 g,
0.13mmol immobilized DEE), THF (5 ml), MeOH (5 ml), and 2 n NaOH (1 ml). After workup, the polymer
was dried in vacuo to a constant mass of 0.230 g (quant.). FT-IR (CCl4): 3311m, 3022w, 2955m, 2927m, 2855m,
1448s, 1428m, 1389m, 1344m, 1173w.
(E)-3,4-Bis{[(tert-butyl)dimethylsilyloxy]methyl}-1,6-bis(4-iodophenyl)hex-3-ene-1,5-diyne (20) and 1,4-
Bis((E)-3,4-bis{[(tert-butyl)dimethylsilyloxy]methyl}-6-(4-iodophenyl)hex-3-ene-1,5-diyn-1-yl)benzene (21).
The following compounds were reacted according to the modified GP 7 (using 19 instead of 7a as chain-
extending building block): immobilized DEE monomer 18 (1.10 g, 0.20 mmol) and 19 (0.332 g, 1.0 mmol). After
workup, the resin-bound products were cleaved according to GP 9: immobilized, phenyl-substituted DEE (1.0 g,
0.16 mmol) and MeI (10 ml). FC (SiO2-60; hexane/CH2Cl2 2 :1) afforded 20 (0.023g, 19%) and 21 (0.052 g,
27%).
Data of 20: Yellow solid. M.p. 1548 1558. UV/VIS (CHCl3): 279 (18200), 316 (27200), 340 (37200), 363
(23800). FT-IR (CHCl3): 2958s, 2872m, 1705w, 1647w, 1432s, 1391m, 1362m, 1314m, 1248m, 1232s, 1215m, 1158s,
1
1120m, 1026w, 861m. H-NMR (300 MHz, CDCl3): 0.13( s, 12 H); 0.93( s, 18 H); 4.58 (s, 4 H); 7.17 (d, J ˆ 8.7,
4 H); 7.68 (d, J ˆ 8.7, 4 H). 13C-NMR (75 MHz, CDCl3): À5.2; 18.3; 25.8; 64.0; 88.2; 94.5; 100.2; 122.8; 129.8;
‡
‡
132.9; 137.7. FT-ICR-MALDI-MS (DHB, two-layer): 791.0708 ([M ‡ Na] , C32H42I2NaO2Si2 ; calc. 791.0711),
‡
‡
‡
‡
768.0758 (M , C32H42I2O2Si2 ; calc. 768.0813), 753.0613 ([ M À Me] ), 711.0112 ([M À t-Bu] ). Anal. calc. for
C32H42I2O2Si2 (768.66): C 50.00, H 5.51; found: C 50.11, H 5.51.
Data of 21: Yellow solid. M.p. 2248 2268. UV/VIS (CHCl3): 257 (24400), 289 (22500), 336 (44500), 372
(60300). FT-IR (CHCl3): 3008s, 2975m, 2924w, 2896w, 2857w, 2431w, 2397m, 1698w, 1652w, 1600m, 1516w,
1
1508w, 1471w, 1443w, 1415w, 1244m, 1046m, 928m, 872m, 83 6m. H-NMR (300 MHz, CDCl3): 0.15 (s, 24 H);
0.94 (s, 36 H); 4.61 (s, 8 H); 7.18 (d, J ˆ 8.4, 4 H); 7.42 (s, 4 H); 7.69 (d, J ˆ 8.4, 4 H). 13C-NMR (75 MHz,
CDCl3): À5.2; 18.3; 25.8; 64.0; 64.1; 88.3; 89.0; 94.5; 100.2; 100.9; 122.8; 123.4; 129.8; 129.9; 131.5; 132.9; 137.7.
‡
‡
FT-ICR-MALDI-MS (DHB, two-layer): 1229.3074 (29, [M ‡ Na] , C58H80I2NaO4Si4 ; calc. 1229.31201),
‡
‡
‡
‡
1206.3191 (83, M ; C58H80I2O4Si4 ; calc. 1206.3223), 1205.3175 (100, [M À H] , C58H79I2O4Si4 ; calc. 1205.3145).
General Procedures for the Synthesis of the Oligo(phenylene Triacetylene)s 7b 7d. a) Unidirectional,
Stepwise Oligomer Growth. The attachment of 4 to Merrifield resin R2 was followed by sequential repetition of
GP 6 and GP 7, until the desired oligomer was synthesized. Finally, this oligomer was cleaved from the solid
support according to GP 9 and purified by FC.
b) Unidirectional, Iterative Divergent/Convergent Oligomer Growth. After attachment of 4 to Merrifield
resin R2, one sequence of GP 6, GP 7, and GP 9 led to dimer 7b, which was purified by FC. This compound was
then subjected to another sequence of GP6, GP7, and GP9 to give, after FC, tetramer 7d.
1-((E)-3,4-Bis{[(tert-butyl)dimethylsilyloxy]methyl}-6-(4-iodophenyl)hex-3-ene-1,5-dyine-1-yl)-4-((E)-
3,4-bis{[(tert-butyl)dimethylsilyloxy]methyl}-6-(trimethylsilyl)hex-3-ene-1,5-diyn-1-yl)benzene (7b). The fol-
lowing compounds were reacted according to GP 9: immobilized DEE dimer (0.800 g, 0.12 mmol) and MeI
(10 ml). FC (SiO2-60; hexane/CH2Cl2 2 :1) afforded 7b (0.106 g, 82%). Yellow solid. M.p. 1798 1808. UV/VIS
(CHCl3): 273 (18900), 321 (37000), 360 (54200). FT-IR (CCl4): 2952m, 2928m, 2925w, 2857m, 2129w, 1504w,
1481w, 1471w, 1465w, 1387w, 1359w, 1251m, 1101m, 1006w, 928w, 83 8s. 1H-NMR (300 MHz, CDCl3): 0.12 (s,
12 H); 0.14 (s, 12 H); 0.22 (s, 9 H); 0.93( s, 36 H); 4.51 (s, 2 H); 4.54 (s, 2 H); 4.59 (s, 2 H); 4.61 (s, 2 H); 7.16 (d,
J ˆ 8.4, 2 H); 7.40 (s, 4 H); 7.68 (d, J ˆ 8.4, 2 H). 13C-NMR (75 MHz, CDCl3): À4.9; 0.0; 18.5; 26.2; 63.9; 64.1;
64.2; 88.2; 88.7; 88.8; 94.5; 100.1; 100.7; 100.8; 101.8; 107.1; 122.6; 123.1; 123.2; 129.6; 129.7; 130.3; 131.2; 132.7,
‡
‡
137.5. FT-ICR-MALDI-MS (DHB, two-layer): 1099.4236 (100, [M ‡ Na] ; C55H85INaO4Si5 ; calc. 1099.4237),
‡
‡
‡
1076.4361 (17, M ; C55H85IO4Si5 ; calc. 1076.4339), 1019.3694 (32, [M À t-Bu] ). Anal. calc. for C55H85IO4Si5
(1077.61): C 61.30, H 7.95; found: C 61.51, H 7.93.
(E)-3,4-Bis{[(tert-butyl)dimethylsilyloxy]methyl}-1-[4-((E)-3,4-bis{[(tert-butyl)dimethylsilyloxy]methyl}-
6-(4-iodophenyl)hex-3-ene-1,5-diyn-1-yl)phenyl]-6-[4-((E)-3,4-bis{[(tert-butyl)dimethylsilyloxy]methyl}-6-(tri-
methylsilyl)hex-3-ene-1,5-diyn-1-yl)phenyl]hex-3-ene-1,5-diyne (7c). The following compounds were reacted
according to GP 9: immobilized DEE trimer (1.300 g, 0.17 mmol) and MeI (13 ml). FC (SiO2-60; hexane/
CH2Cl2 2 :1) afforded 7c (0.144 g, 56%). Yellow solid. M.p. 2308 23 18. UV/VIS (CHCl3): 283(25400), 309 (sh,
36200), 381 (97800). FT-IR (CCl4): 3005s, 2973m, 2927w, 2890w, 2853w, 2433w, 2396m, 1600m, 1510w, 1443w,
1253m, 1138w, 1043m, 93 1m, 83 6m. 1H-NMR (300 MHz, CDCl3): 0.11 (s, 12 H); 0.13( s, 24 H); 0.21 (s, 9 H); 0.92
(s, 54 H); 4.50 (s, 2 H); 4.53( s, 2 H); 4.59 (br. s, 8 H); 7.15 (d, J ˆ 8.1, 2 H); 7.39 (m, 4 H), 7.40 (m, 4 H); 7.67 (d,
J ˆ 8.1, 2 H). 13C-NMR (75 MHz, CDCl3): À5.0; À0.2; 18.6; 25.9; 63.9; 64.1; 88.3; 88.7; 88.8; 94.5; 100.2; 100.8;

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Helvetica Chimica Acta Vol. 87 (2004)
100.9; 101.0; 101.8 107.2; 122.6; 123.2; 123.3; 128.7; 129.8; 130.5; 130.9; 131.4; 132.4; 132.8, 137.6. FT-ICR-
‡
‡
‡
MALDI-MS (DHB, two-layer): 1537.6630 ([M ‡ Na] , C81H123INaO6Si7 ; calc. 1537.6647), 1514.6686 (M ,
‡
‡
C81H123IO6Si7 ; calc. 1514.6749), 1457.6062 (6, [M À t-Bu] ). Anal. calc. for C81H123IO6Si7 (1516.37): C 64.16,
H 8.18; found: C 64.31, H 7.99.
1-{(E)-3,4-bis{[(tert-butyl)dimethylsilyloxy]methyl}-6-[4-((E)-3,4-bis{[(tert-butyl)dimethylsilyloxy]meth-
yl}-6-(4-iodophenyl)hex-3-ene-1,5-diyn-1-yl)phenyl]hex-3-ene-1,5-diyn-1-yl}-4-((E)-3,4-bis{[(tert-butyl)dime-
thylsilyl-oxy]methyl}-6-[4-((E)-3,4-bis{[(tert-butyl)dimethylsilyloxy]methyl}-6-(trimethylsilyl)hex-3-ene-1,5-
diyn-1-yl)phenyl]hex-3-ene-1,5-diyn-1-yl)benzene (7d). The following compounds were reacted according to
GP 9: immobilized DEE tetramer (0.830 g, 0.099 mmol) and MeI (10 ml). FC (SiO2-60; hexane/CH2Cl2 2 :1 !
0 :1) afforded 7d (0.070 g, 36%). Yellow solid. M.p. > 2408 (dec.). UV/VIS (CHCl3): 384 (122000). FT-IR
(CCl4): 3009s, 2973m, 2928w, 2854w, 2431w, 2394m, 1600m, 1517w, 1445w, 1332w, 1253m, 1140w, 1045m, 1029w,
1
965w, 929m, 875w, 83 6m. H-NMR (300 MHz, CDCl3): 0.12 0.16 (48 H); 0.21 (s, 9 H); 0.92 0.95 (m, 72 H);
4.51 (s, 2 H); 4.54 (s, 2 H); 4.59 4.63( m, 12 H); 7.17 (d, J ˆ 8.4, 2 H); 7.40 7.42 (m, 12 H); 7.68 (d, J ˆ 8.4, 2 H).
13C-NMR (75 MHz, CDCl3): À5.1; À0.2; 18.3; 25.9; 63.7; 63.9; 88.0; 88.5; 88.7; 88.8; 94.2; 100.0; 100.5; 100.6;
100.7; 101.6; 106.9; 122.4; 123.0; 123.3; 128.5; 129.5; 130.1; 130.5; 131.1; 132.1; 132.5, 137.3. FT-ICR-MALDI-MS
‡
‡
‡
(DCTB): 1976.9069 (100, [M ‡ H ‡ Na] , C107H162INaO8Si9 ; calc. 1976.9316), 1895.8357 (37, [M À t-Bu] ).
Anal. calc. for C107H161IO8Si9 (1955.12): C 65.73, H 8.30; found: C 65.77, H 8.29.
(E)-3,4-Bis{[(tert-butyl)dimethylsilyloxy]methyl}-1-(4-iodophenyl)hex-3-ene-1,5-diyne (22). The following
compounds were reacted according to GP 1: 7a (0.120 g, 0.188 mmol), THF (40 ml), MeOH (40 ml), and 2n
NaOH (1 ml). Workup afforded 22 (0.091 g, 85%). Colorless solid. M.p. 1198 1208. FT-IR (CCl4): 3308w, 2955s,
1
2929s, 2856m, 1712m, 1583w, 1471m, 1389w, 1253s, 1057m, 1005m. H-NMR (300 MHz, CDCl3): 0.11 (12 H);
0.92 (18 H); 3.56 (s, 1 H); 4.52 (s, 2 H); 4.53( s, 2 H); 7.16 (d, J ˆ 8.4, 2 H); 7.67 (d, J ˆ 8.4, 2 H). 13C-NMR
(75 MHz, CDCl3): À5.0; 18.4; 25.9; 63.8; 64.0; 80.5; 87.6; 90.0; 94.6; 100.0; 122.5; 131.3; 132.4; 133.5; 137.3. FT-
‡
‡
ICR-MALDI-MS (DHB, two-layer): 589.1421 (100, [M ‡ Na] , C26H39INaO2Si2 ; calc. 589.1431). Anal. calc. for
C26H39IO2Si2 (566.67): C 55.11, H 6.94; found: C 55.28, H 6.78.
(E,E)-3,4,9,10-Tetrakis{[(tert-butyl)dimethylsilyloxy]methyl}-1,12-bis(4-iodophenyl)-dodeca-3,9-dien-
1,5,7,11-tetrayne (23). To 22 (0.091 g, 0.16 mmol) in CH2Cl2 (40 ml), Hay catalyst soln. (0.6 ml) was added. The
soln. was stirred 18 h at r.t. and then passed through a plug (SiO2-60; CH2Cl2). Evaporation in vacuo and FC
(SiO2-60; hexane/CH2Cl2 2 :1 ! CH2Cl2) afforded 23 (0.035 g, 19%). Yellow solid. M.p. 1668 1688. UV/VIS
(CHCl3): 256 (26900), 366 (57100), 379 (sh, 55800), 408 (sh, 37100). FT-IR (CCl4): 2952s, 2925s, 2885m, 2857s,
1
2358m, 1482m, 1471m, 1459w, 1359w, 1256m, 1099m, 1024w, 1008m, 906s, 83 6s. H-NMR (300 MHz, CDCl3):
0.12 (s, 24 H); 0.93( s, 36 H); 4.52 (s, 4 H); 4.54 (s, 4 H); 7.16 (d, J ˆ 8.4, 4 H); 7.68 (d, J ˆ 8.4, 4 H). 13C-NMR
(75 MHz, CDCl3): À4.9; 18.5; 25.9; 63.9; 64.0; 82.4; 85.9; 88.0; 94.7; 102.0; 122.3; 128.7; 132.7; 133.1, 137.5. FT-
‡
‡
‡
ICR-MALDI-MS (DCTB): 1153.2789 (100, [M ‡ Na] , C52H76INaO4Si4 ; calc. 1153.2808), 1130.2777 (18, M ,
‡
‡
C52H76IO4Si4I ; calc. 1130.2910), 1073.2084 (17, [M À t-Bu] ). Anal. calc. for C52H76I2O4Si4 (1131.32): C 55.21,
H 6.77; found: C 55.04, H 6.84.
CadiotÀChodkiewicz Coupling on Solid Phase. The following compounds were reacted according to GP 8:
immobilized DEE monomer 18 (0.500 g, 0.085 mmol), 11 (0.219 g, 0.43mmol), LiI (0.002 g, 0.017 mmol), PMP
(0.04 ml, 0.238 mmol), [Pd2(dba)3] (0.0022 g, 0.0026 mmol, 3mol-%), and benzene (9 ml). After workup, the
resin-bound products were cleaved according to GP 9: immobilized DEE derivatives (0.48 g) and MeI (5 ml).
FC (SiO2-60; hexane/CH2Cl2 2 :1) afforded 22 (0.001 g, 2%) and an inseparable mixture of 15 and 23. Further
investigation of this mixture by calibrated, anal. HPLC (hexane/CH2Cl2 2 :1) provided 15 (37%) and 23 (10%).
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Received October 7, 2003