An iterative approach to cis-oligodiacetylenes

Article abstract of DOI:10.1002/1099-0690(200110)2001:20<3879::AID-EJOC3879>3.0.CO;2-K

Phenyl-terminated cis-oligodiacetylenes such as 18, containing a π-conjugated backbone with four triple and three double bonds, were synthesized using Pd-catalysed Sonogashira coupling reactions. Compound 18 represents the longest cis-oligoenyne system to date, but it suffers from the drawback of cis/trans isomerization observed in solution. In order to avoid cis/trans isomerization in such cis-oligodicacetylenes, the ene moieties within the oligomeric backbone were locked by incorporation into ring systems. 1,2-Dibromocyclopentene was used as an olefinic building block for this purpose, permitting the iterative synthesis of the cis-oligodiacetylenes 27 and 28, possessing the same π-conjugated backbone as 18. Unlike that compound, however, 27 and 28 are stable both in solution and in the solid state. Whereas X-ray crystallography revealed a completely planar structure for 27 in the single crystal, NMR and computational investigations suggest that a preferred helical conformation is likely in solution.

Full text of DOI:10.1002/1099-0690(200110)2001:20<3879::AID-EJOC3879>3.0.CO;2-K

FULL PAPER
An Iterative Approach to cis-Oligodiacetylenes
Christoph Kosinski,[a] Andreas Hirsch,*[a] Frank W. Heinemann,[b] and Frank Hampel[a]
Dedicated to Professor Michael Hanack on the occasion of his 70th birthday
Keywords: Enynes / Helical structures / Oligodiacetylenes / Sonogashira coupling
Phenyl-terminated cis-oligodiacetylenes such as 18, con- cyclopentene was used as an olefinic building block for this
taining a π-conjugated backbone with four triple and three
purpose, permitting the iterative synthesis of the cis-oligodia-
double bonds, were synthesized using Pd-catalysed Sonoga- cetylenes 27 and 28, possessing the same π-conjugated back-
shira coupling reactions. Compound 18 represents the long-
est cis-oligoenyne system to date, but it suffers from the
drawback of cis/trans isomerization observed in solution. In
bone as 18. Unlike that compound, however, 27 and 28 are
stable both in solution and in the solid state. Whereas X-ray
crystallography revealed a completely planar structure for 27
order to avoid cis/trans isomerization in such cis-oligodicace- in the single crystal, NMR and computational investigations
tylenes, the ene moieties within the oligomeric backbone
suggest that a preferred helical conformation is likely in solu-
were locked by incorporation into ring systems. 1,2-Dibromo- tion.
Introduction
The synthesis of π-conjugated oligomers[2,9] is also of in-
terest because it is anticipated that these oligomers should
be important components of molecular electronic devices.
Moreover, they can serve as constrained model systems, the
spectroscopic properties of which can be extrapolated to en-
able the electronic, optical, thermal, and morphological
properties of the corresponding polymers[4,10] to be pre-
dicted. Polydiacetylenes 2 have not been investigated to the
same extent as other linear oligomers of π-conjugated, non-
aromatic, all-carbon backbones, presumably due to the fact
that it is difficult to find a topochemically controlled syn-
thesis of their π-conjugated backbone.[9] The first studies of
the synthesis of the polydiacetylenes go back to Slysh, Geor-
giana, and Desai in 1960,[11] who investigated the polymeriz-
ation of butadiyne (diacetylene), C4H2. The first systematic
series of trans-enyne oligomers, dating back to 1986, was
published by Wudl and Bittler,[12] who reported the synthesis
of tert-butyl-endcapped oligomers. The tert-butyl endcaps
were found to be essential for sufficient thermal stability,
with the oligomers displaying no particular sensitivity to air
and light, as is generally observed in the case of oligoenes. In
1992, Lindsell produced the phenyl-endcapped trans-enyne
oligomer 6.[13] In 1992, Bergman’s group published the syn-
thesis of the longest all-cis oligomer 7 so far, together with
its cis,trans and trans,trans isomers.[14]
Linear polymers with π-conjugated carbon scaffolds are
predicted to have special electronic and optical proper-
ties.[1,2] Stepwise reduction in saturation of the carbon scaf-
fold, starting with polyacetylene 1,[3] produces the hypothet-
ical carbon allotrope carbyne 5,[4,5] via polydiacetylene 2[6]
or polytriacetylene 4.[7] Another π-conjugated carbon scaf-
fold is represented by the cross-conjugated system 3.[8]
[a]
Institut für Organische Chemie der Universität Erlangen-
Nürnberg
Henkestr. 42, 91054 Erlangen, Germany
Fax: (internat.) ϩ 49-(0)9131/852-6864
E-mail: hirsch@organik.uni-erlangen.de
[b]
Institut für Anorganische Chemie der Universität Erlangen-
Nürnberg
Egerlandstr. 1, 91058 Erlangen, Germany
Eur. J. Org. Chem. 2001, 3879Ϫ3890
WILEY-VCH Verlag GmbH, 69451 Weinheim, 2001
1434Ϫ193X/01/1020Ϫ3879 $ 17.50ϩ.50/0
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C. Kosinski, A. Hirsch, F. W. Heinemann, F. Hampel
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The number of synthetic approaches to cis-enyne oligo-
mers is very limited.[13,14] Here we introduce our new iterat-
ive approach for a homologous series of cis-oligoacetyl-
enes 8.
Scheme 2. Synthesis of 14: a) K2CO3, CH3OH/H2O, room temp.,
6 h, then 10 (1.9 equiv.), Pd(PPh3)4, CuI, nBuNH2, C6H6, room
temp., 100 h, 42% (2 steps)
We refrained from purification and characterisation of
the unprotected alkynes because of the poor stability of
these compounds. Further experiments to elongate the
chain by coupling with TMS-acetylene were unsuccessful.
Since the instability of the products precluded purification,
we modified the synthesis route and decided to use TIPS
instead of TMS as protecting group. Analogously to the
synthesis of 12, the chloride 11 was coupled with TIPS-
acetylene to generate 15 in 94% yield (Scheme 3). Removal
of the TIPS protecting group with TBAF and coupling of
the product with (Z)-1,2-dichloroethene (10) afforded 14 in
up to 41% yield. Subsequent treatment of 14 with TIPS-
acetylene produced 16 in 41% yield, but further coupling
steps were unsuccessful.
Results and Discussion
Our strategy for the construction of cis-enyne oligomers
is based on the Sonogashira Pd-catalysed sp-sp2 coupling
of terminal acetylenes with vinyl halides in the presence of
an amine and CuI.[15] Use of the phenyl group as the
endcap turned out to be favourable for this approach, as it
caused an increase in the reactivity of the π-conjugated car-
bon chain. The synthesis of a first series of cis-enyne oligo-
mers started with the coupling of phenylacetylene 9 and 2.0
equiv. of (Z)-1,2-dichloroethene (10) (Scheme 1), producing
11[16] in 76% yield. Subsequently, 11 was treated with
phenylacetylene (9) to yield [(3Z)-6-phenylhex-3-ene-1,5-di-
ynyl]benzene (13) (87%). Treatment of 11 with TMS-acetyl-
ene gave 12[17] in up to 84% yield.
Scheme 3. Preparation of 16: a) TIPS-acetylene (1.2 equiv.),
Pd(PPh3)4, CuI, nBuNH2, C6H6, room temp., 72 h, 94%; b) TBAF,
THF/H2O, 3 h, then 10 (1.4 equiv.), Pd(PPh3)4, CuI, nBuNH2,
C6H6, room temp., 100 h, 41% (2 steps); c) TIPS-acetylene (1.5
equiv.), Pd(PPh3)4, CuI, nBuNH2, C6H6, room temp., 20 h, 41%
Scheme 1. Synthesis of 12 and 13: a) Pd(PPh3)4, CuI, nBuNH2,
C6H6, room temp., 24 h, 76%; b) TMS-acetylene (1.3 equiv.),
Pd(PPh3)4, CuI, nBuNH2, C6H6, room temp., 48 h, 84%; c) · 9 (1.0
equiv.), Pd(PPh3)4, CuI, nBuNH2, C6H6, room temp., 24 h, 87%
When we started from 12, however, we were able to syn-
thesize the cis-oligoeneynes 17 and 18 in yields of 29% and
The next step involved the cleavage of the TMS pro- 6%, respectively (Scheme 4). Compound 18 is longer than
tecting group by the action of a solution of potassium car- 7[14] and is the all-cis isomer of the all-trans-6 synthesized
bonate in methanol to afford the terminal alkyne interme- by Lindsell.[13] To extend the range of compounds available
diate. This was coupled in situ with 1.5 equiv. of (Z)-1,2- for comparative purposes, we also synthesized 19, from 1-
dichloroethene (10) under Sonogashira conditions to give hexyne and (Z)-1,2-dichloroethene (10), in 80% yield
14 in up to 42% yield (Scheme 2).
(Scheme 5).[18]
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An Iterative Approach to cis-Oligodiacetylenes
FULL PAPER
among other things for the synthesis of platyrins from the
group of the porphyrins.[19] This should simultaneously pre-
vent both polymerization, thanks to steric obstruction, and
also cis/trans isomerization of the double bond (Figure 1).
As the cyclic olefin we used 1,2-dibromocyclopentene
(20).[20]
Figure 1. Stabilisation of the enyne backbones in cis-polydiacetyl-
enes by introduction of ene moieties into a ring system
Scheme 4. Synthesis of 17 and 18: a) K2CO3, CH3OH/H2O, room
temp., 6 h, then 11 (1.2 equiv.), Pd(PPh3)4, CuI, nBuNH2, C6H6,
room temp., 24 h, 29% (2 steps); b) K2CO3, CH3OH/H2O, room
temp., 6 h, then 10 (0.4 equiv.), Pd(PPh3)4, CuI, nBuNH2, C6H6,
room temp., 72 h, 6% (2 steps)
The change in the ethylene component had the further
advantage of enabling us to use PdCl2(PPh3)2 as the catalyst
instead of Pd(PPh3)4; this produced better results than
those found in the synthesis of the ‘‘naked’’ chain. Like the
synthesis of the ‘‘naked’’ cis-enyne chains, that of the ‘‘pro-
tected’’ chain started with the coupling of phenylacetylene
(9) with 1,2-dibromocyclopentene (20). In contrast with the
synthesis described above, this technique always afforded a
mixture of the products 21 and 22, together with small
Scheme 5. Synthesis of 19: a) 10 (0.5 equiv.), Pd(PPh3)4, CuI, amounts of (4-phenylbuta-1,3-diinyl)benzene, which was
nBuNH2, C6H6, room temp., 80 h, 80%
separated by column chromatography with hexane/dichlor-
omethane (15:1 and 10:1; Scheme 6).
Although the generation of a series of cis-oligoenynes
proved successful, it must be noted that their isolation and
handling posed some difficulties. The instability of these
systems is evident from the observed cis/trans isomerization
and ease of polymerization. A clear example of cis/trans
1
isomerization is provided by compound 18. The H NMR
signals of the hydrogen atoms of the central double bond
give a singlet at δ ϭ 7.96, while two doublets at δ ϭ 5.94
and 6.70 are observed for the hydrogen atoms of the outer
double bonds. The coupling constant is 12.0 Hz, typical for
cis double bonds. After only a short time, however, changes
can be observed in the 1H NMR spectrum of 18. Alongside
the old signals, new peaks appear at δ ϭ 7.39 (singlet) for
the central double bond and at δ ϭ 6.39 and 7.01 (two
Scheme 6. Preparation of 21 and 22: a) PdCl2(PPh3)2, CuI,
nBuNH2, C6H6, room temp., 6 h
Compound 21 was coupled with 4.0 equiv. of TMS-acet-
doublets with the typical trans coupling constant of ylene in a Sonogashira reaction to afford 23 in 91% yield
16.1 Hz) for the outer double bonds. We also observed (Scheme 7). Before the chain was elongated further, the
changes in the chemical shifts of the olefinic carbon atoms TMS group was cleaved by treatment with methanolic pot-
in the 13C NMR spectrum: The carbon atoms of the central assium carbonate solution. The reaction proceeded almost
bond in the all-cis isomer resonated at δ ϭ 128.67 and those quantitatively, but we refrained from isolation and charac-
of the outer double bonds at δ ϭ 107.80 and 138.09; the terization of the product because of the instability of the
corresponding values for the all-trans isomer are δ ϭ deprotected form. Coupling of 23 with 1.2 equiv. of 1,2-
1
126.66, 108.48, and 140.52, respectively. In the H NMR dibromocyclopentene (20) resulted in 24. The yield after
spectrum of 17, we unexpectedly found only one peak for two steps was 36%. A yield of 99% was obtained for the
the four olefinic hydrogen atoms at δ ϭ 6.14. As anticip- coupling of 24 with TMS-acetylene to give 25. Removal of
ated, however, the 13C NMR spectrum contained two peaks the TMS protecting group and coupling with 1.1 equiv. of
for the four olefinic carbon atoms at δ ϭ 118.98 and 119.97 1,2-dibromocyclopentene (20) gave 26 in a yield of 22%. In
and three peaks for the acetylenic C atoms at δ ϭ 87.23, the next step, compound 27 was obtained in 81% yield on
94.98, and 98.27.
treatment of 26 with 6.0 equiv. of TMS-acetylene.
In order to circumvent these problems associated with
We obtained 28 in 9% yield from 23, by removal of the
instability and isomerization, we decided to use cyclic TMS group and subsequent Sonogashira coupling with
double bond moieties Ϫ a well established concept used 0.45 equiv. of 1,2-dibromocyclopentene (20) (Scheme 8).
Eur. J. Org. Chem. 2001, 3879Ϫ3890
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C. Kosinski, A. Hirsch, F. W. Heinemann, F. Hampel
FULL PAPER
Scheme 9. Synthesis of 29, 30 and 31: a) 20 (0.25 equiv.),
PdCl2(PPh3)2, CuI, nBuNH2, C6H6, room temp., 48 h, 87%; b) 20,
PdCl2(PPh3)2, CuI, nBuNH2, C6H6, room temp., 18 h
compounds with larger π-conjugated systems exhibit ba-
thochromic shifts and increases in extinction coefficients.
This is evident in the colour of the compounds either in
solution or as solids; the colours become more intense and
change from white or yellow (compounds 21, 22, 23, 24,
and 25, for example) to brownish (26 and 28) or orange
(27). Figure 2, a), shows spectra of selected examples with
‘‘naked’’ chains (19 and 13) and with ‘‘protected’’ chains
(29 and 22). A comparison of the spectra demonstrates that
the presence of the cyclopentene ring has a negligible influ-
ence on the UV absorption, since 19 and 13 have spectra
very similar to those of 29 and 22, respectively. Only a weak
increase in absorbance can be discerned. The use of phenyl
groups, which conjugate with the π-system of the diacetyl-
ene, in place of alkyl groups has a much greater influence
on the absorption. In this case, both the absorbance and
the peak wavelengths increase. The shift of the maxima with
increasing chain length is shown in Figure 2, b). Com-
pounds 24 and 26 have essentially similar UV spectra, but
that of 21 is quite different, presumably because it lacks an
enediyne moiety.
Scheme 7. Synthesis of 27: a) TMS-acetylene (4.0 equiv.),
PdCl2(PPh3)2, CuI, nBuNH2, C6H6, room temp., 24 h, 91%; b)
K2CO3, CH3OH/H2O, room temp., 16 h, then 20 (1.2 equiv.),
PdCl2(PPh3)2, CuI, nBuNH2, C6H6, room temp., 20 h, 36% (2
steps); c) TMS-acetylene (4.0 equiv.), PdCl2(PPh3)2, CuI, nBuNH2,
C6H6, room temp., 48 h, 99%; d) K2CO3, CH3OH/H2O, room
temp., 36 h, then 20 (1.1 equiv.), PdCl2(PPh3)2, CuI, nBuNH2,
C6H6, room temp., 72 h, 22% (2 steps); e) TMS-acetylene (6.0
equiv.), PdCl2(PPh3)2, CuI, nBuNH2, C6H6, room temp., 72 h, 81%
Compound 24 was generated as a by-product in this reac-
tion (19% yield).
Finally, we can see in Figure 2, c), that the substitution
of one phenyl group by a TMS protecting group (no con-
jugation with the π-system) in the compounds with highest
chain length (27 and 28) has a strong effect on absorbances
and peak maxima, but only a limited influence on the relat-
ive appearance of the UV spectra.
Scheme 8. Preparation of 28: a) K2CO3, CH3OH/H2O, room temp.,
20 h, then 20 (0.45 equiv.), PdCl2(PPh3)2, CuI, nBuNH2, C6H6,
room temp., 20 h, 9% (2 steps)
The IR stretching modes of all the acetylenes synthesized
We obtained compound 29 in 87% yield from 1,2-dibro- appear between 2130 and 2218 cmϪ1. The olefinic valence
mocyclopentene (20), by coupling with 1-pentyne. De- vibrations appear from 1628Ϫ1677 cmϪ1 and are in general
pending on the amount of 20 used, coupling with TMS- much more easily observable in the ‘‘naked’’ chains than in
acetylene would produce either a mixture of the two prod- the ‘‘protected’’ ones. The cis-olefinic deformation modes
ucts 30 and 31, or 31 exclusively (Scheme 9).
always appear at 744 cmϪ1 for 19 and between 678 and 700
All products were purified by column chromatography cmϪ1 for the other compounds.
and were completely characterized by IR, UV/Vis, 1H
The 13C NMR signals of the acetylenic carbon atoms ap-
NMR, 13C NMR, MS, and microanalysis. The UV spectra pear between δ ϭ 83 and 98 for C atoms bonded to sp2-
of selected molecules are shown in Figure 2. In general, hybridized carbon atoms, δ ϭ 100Ϫ103 for those from the
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An Iterative Approach to cis-Oligodiacetylenes
FULL PAPER
The compounds with three cyclopentene rings (26, 27,
and 28) display interesting behaviour in solution, in com-
parison with their smaller homologues. This is shown in the
1H NMR spectra of molecules 27 and 28 (Figure 3). The
hydrogen atoms of the two outer cyclopentene rings A of
the symmetrical compound 28 have chemical shifts of δ ϭ
1.73 and 2.46 and are shifted to a higher field than those
of the rings in the centre (δ ϭ 1.92 or 2.61).
Figure 3. The 1H NMR shifts of the cyclopentene rings of com-
pounds 21, 23, 24, 25, 26, 27, and 28; upfield shifts of the cyclopen-
tene C ring signals of 26 and 27 and of the A ring signals of the
symmetrical compound 28 are apparent
Different behaviour is observed in the unsymmetrical
compound 27. In this case, the hydrogen atoms of the cyclo-
pentenes A and B show the same chemical shifts, δ ϭ 1.96
and 2.63. It is conspicuous that the chemical shifts of the
hydrogen atoms of the cyclopentenes A in compound 28
are almost identical to the shifts of those of ring C in com-
pound 27 (δ ϭ 1.70 or 2.43), and they are shifted upfield
relative to those of ring B. The best explanation for this
behaviour is the adoption of a helical conformation by
compounds 27 and 28 (Figure 4).
Figure 2. The UV spectra of selected compounds (further details
in the text)
Many organic molecules are helical.[21] The conformation
TMS- and TIPS-acetylene groups, and δ ϭ 77 to 78 for of natural biopolymers is stabilized by, among other things,
acetylenic atoms bound to sp3-hybridized C atoms (com- localised non-covalent interactions such as hydrogen bond-
pounds 19 and 29). For the olefinic carbon atoms, there is ing, hydrophobic, and van der Waals forces.[22] In nonbiolo-
a general trend towards upfield shifting of the olefinic C gical macromolecules, particularly when dissolved in polar
atoms of the ‘‘naked’’ chain (δ ϭ 112Ϫ129) relative to the solvents, these forces are relatively unimportant.[23] In this
C atoms of the ‘‘protected’’ diacetylenes (δ ϭ 124Ϫ132).
case, the structure of the molecules arises from nonspecific
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C. Kosinski, A. Hirsch, F. W. Heinemann, F. Hampel
FULL PAPER
of the centre double bond (δ ϭ 7.96). This may be an in-
dication of a helical conformation in this molecule in solu-
tion. However, this result should not be overemphasised, as
no ‘‘naked’’ chain compounds analogous to 26 and 27 have
been prepared.
According to PM3 calculations[27] on compounds 27 and
28, the helical conformation is favoured over the chain by
about 1.9 and 1.3 kcal/mol respectively. In contrast, the
chain form of compound 26 is about 1.5 kcal/mol more
stable than the helix. These values are similar to the error
limits intrinsic to the method and they are too low to allow
ascertainment of which of these conformations would occur
in the gas phase. Another interesting result appeared when
we optimized the structure of 22 with ab initio methods[28]
[the calculations were performed at the standard MP2(fc)/
6-311ϩG(d,p) level using Gaussian98 Rev. A.5]. According
to these calculations, the whole molecule, including the
cyclopentene ring, should have a flat structure.
Recrystallization of compound 22 by diffusion of hexane
into a dichloromethane solution produced crystals suitable
for X-ray analysis. This structural analysis of 22, which
crystallised in the monoclinic system, confirms this unex-
pected result [Figure 6, a) and b)]. The cyclopentene ring
has a flat structure and, furthermore, the molecule as a
whole is almost flat, as predicated by the calculation. Only
one phenyl ring shows a slight twist out of the molecular
plane. The planar structure of the molecule permits efficient
packing [Figure 6, c) and d)] of the molecules within the
unit cell to form a ‘‘herringbone’’ pattern. The distance be-
tween each layer amounts to 462.3 pm, which allows only
weak van der Waals forces between the molecules.
Figure 4. The backbone can adopt a transoid or a cisoid conforma-
tion by rotation about the triple bond
forces such as solvophobic interactions[24] and πϪπ interac-
tion[25] of aromatic units. Moore has recently observed that
certain phenylene-ethylene oligomers undergo a cooperative
conformational transition in solution, from a random state
to a putative helical structure stabilized by the π-stacking
of aromatic residues.[26]
In the PM3-calculated helical conformers of 27 and 28,
both cyclopentenes A of 28 and ring C of 27 lie directly
over phenyl rings (Figure 5) and so are situated in the shi-
elding region due to the diamagnetic ring current. This con-
sequently results in a weak upfield shifting of these proton
signals.
Compound 27 crystallised out of [D2]dichloromethane
with one molecule of CD2Cl2 in every formula unit (Fig-
ure 7). The molecule and the solvent are located on the
crystallographic mirror plane of the space group Pmn21 of
the orthorhombic system. The molecules crystallize in al-
ternately repeating layers [Figure 7, c)]. The TMS groups
within each layer all point in the same direction, but the
TMS groups in the adjacent layers point in the opposite
direction, to achieve the highest possible packing efficiency.
Because of this arrangement of the molecules within the
crystal, the intermolecular distance between apparent
stacking partners [Figure 7, b)] comes to 710.7 pm, signific-
antly greater than that found in 22. This is also more than
double the distance associated with the usual πϪπ stacking
separation observed in aromatic[29] compounds and graph-
ite (335.4 pm).[30] At this distance, only very weak van der
Waals forces and πϪπ interactions are to be expected.
In the X-ray analysis of 22 and 27, the planar structure
Figure 5. POV-ray representations of the PM3-optimized structures
of 27 (a) and 28 (b) in the helical conformation (grey ϭ carbon,
white small ϭ hydrogen, white large ϭ silicon; left: side view of the
helix; right: view through the helix; the spatial proximity to the
phenyl rings of the cyclopentene A ring in 28 and the C ring in 27
is apparent
Compound 26 shows similar behaviour to its short-chain
homologues 21 and 24 in the protons at the cyclopentene of the molecule is noteworthy: It provides evidence of full
ring C. The signal of the methylene group in the centre, for conjugation of the π-backbone of both compounds within
example, shows an upfield shift [δ ϭ 1.76, compared to δ ϭ the crystal. Another indication of the distinct conjugation
1.91 in the A and B rings and δ ϭ 2.02 (21) and δ ϭ 1.99 of the π-backbone is given by comparison of the CϪC bond
(24)], an indication that molecule 26 is present in helical lengths within the crystal. Whereas the lengths of the
form. The same pattern is observed for the other methylene double and triple bonds lie in the usual ranges (120Ϫ121
group in the C ring. In the ‘‘naked’’ chain compound 18, pm for the triple bonds, 134Ϫ136 pm for the nonaromatic
1
the H NMR signals of the two outer double bond hydro- double bonds and 137Ϫ139 pm for the aromatic CϪC
gen atoms are observed upfield (δ ϭ 5.94 and 6.70) of those bonds), the single bonds of the chain are significantly
3884
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An Iterative Approach to cis-Oligodiacetylenes
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Figure 6. X-ray crystal structure of compound 22 (hydrogen atoms omitted for clarity): a) view of the molecule plane; b) side view; c)
˚
and d) arrangement of the molecules within the unit cell; selected bond lengths [A] and angles [°]: C(3)ϪC(61) 1.432(3), C(2)ϪC(3)
1.199(3), C(2)ϪC(11) 1.420(3), C(11)ϪC(12) 1.346(3), C(11)ϪC(15) 1.503(3), C(14)ϪC(15) 1.510(3); C(2)ϪC(3)ϪC(61) 176.6(2),
C(3)ϪC(2)ϪC(11) 178.0(2), C(12)ϪC(11)ϪC(2) 125.4(2), C(2)ϪC(11)ϪC(15) 123.3(2), C(12)ϪC(11)ϪC(15) 111.3(2),
C(11)ϪC(15)ϪC(14) 104.5(2), C(13)ϪC(14)ϪC(15) 108.0(2)
shorter, 141Ϫ143 pm instead of the usual 154 pm. The NMR and computational investigations suggest that a pre-
CϪC single bonds of the cyclopentene rings are of normal ferred helical conformation is likely in solution. The syn-
length (150Ϫ154 pm). The CϪSi bond lengths of 27 are the thesis of even longer oligoenynes is currently underway.
typical 185Ϫ186 pm.
Experimental Section
Conclusion
General Remarks: 1H NMR and 13C NMR: Jeol JNM EX 400 and
Jeol JNM GX 400. Ϫ MS: Varian MAT 311 A (EI), Micromass
The longest oligoenyne described up to now was (Z,Z)-
ZabSpec (FAB). Ϫ IR: Bruker FT-IR Vector 22. Ϫ UV/Vis: Shim-
deca-3,7-diene-1,5,9-triyne (7), synthesized by Bergman in
adzu UV 3102 PC. Ϫ Elemental analysis: EA 1110 CHNS, CE
1992.[14] By using cyclic 1,2-dibromocyclopentene as a con-
formationally locked olefinic building block, we have been
able to synthesize stable phenyl-terminated cis-oligoenynes
containing backbones with up to seven conjugated triple
and double bonds, in an iterative approach based on Pd-
catalysed Sonogashira coupling reactions. Whereas these
Instruments. Ϫ Melting point apparatus: IA 9100, Electrothermal
(values are uncorrected). Ϫ Preparative HPLC: Shimadzu Class
LC10, SIL 10A, SPD 10A, CBM 10A, LC 8A, FRC 10A (Nucleo-
sil, 5 µm, 200 ϫ 4). Ϫ Analytical HPLC: Shimadzu Class LC10,
SIL 10A, SPD-M10A, CBM 10A, LC 10AT (Nucleosil, 5 µm, 250
ϫ 21). Ϫ TLC: Merck, silica gel 60 F 254 nm, viewing by UV or
molecules are completely planar in the solid state, both by staining with molybdophosphoric acid and cerium sulfate in
Eur. J. Org. Chem. 2001, 3879Ϫ3890 3885

C. Kosinski, A. Hirsch, F. W. Heinemann, F. Hampel
FULL PAPER
particle size 0.04Ϫ0.063 nm, Merck). The semiempirical PM3 cal-
culations were carried out with the PC software package VAMP
7.0a[32] and HyperChem 5.1 or HyperChem 6.0. IUPAC names
were generated with the software package ACDLabs Chem Sketch
for WINDOWS 4.02. In the assignment of the NMR signals of
protected chains, the numbering of the carbon atoms always starts
at the acetylenic carbon atom connected to the ipso-carbon atom
of the phenyl group, irrespective of the IUPAC nomenclature. The
numbering of the carbon atoms of the unprotected chain corre-
sponds to IUPAC nomenclature.
General Procedure I for the Sonogashira Coupling: A vinyl halide
component, the acetylene compound, and lastly nBuNH2 (5Ϫ6
equiv.) were added to a solution of Pd(PPh3)4 or PdCl2(PPh3)2
(4Ϫ10 mol %) and CuI (4Ϫ10 mol %) in benzene (2Ϫ3 mL/mmol).
The reaction mixture was stirred for 18Ϫ100 h (TLC monitoring)
and was transferred to a separating funnel. The organic layer was
washed with 10% hydrochloric acid (2 ϫ 40 mL), saturated
NaHCO3 (aq) (1 ϫ 30 mL), and brine (1 ϫ 50 mL), dried with
Na2SO4 and filtered. Evaporation of the solvent gave the crude
product (usually brown oil), which was purified by FC or HPLC.
General Procedure II for the Removal of TMS Protecting Group:
The TMS-protected compound was dissolved in 1 mL of THF and
the resulting solution was diluted with methanol (2Ϫ3 mL/mmol).
A few drops of water were added to the solution, which was then
cooled to 0 °C. K2CO3 (about 6Ϫ8 equiv.) was added. The mixture
was stirred for 30 min at 0 °C, and then for 6Ϫ36 h at room temper-
ature (TLC monitoring). The reaction mixture was then poured
into a separating funnel containing 100 mL of diethyl ether and 50
mL of iced H2O. The organic layer was washed with iced H2O (4
ϫ 25 mL) and brine (1 ϫ 30 mL), dried with Na2SO4, and filtered.
The solution was concentrated under vacuum and used directly in
the next step.
[(3Z)-4-Chlorobut-3-en-1-ynyl]benzene (11):[16] Compound 11 was
synthesized according to general procedure I, with phenylacetylene
(2.50 g) and (Z)-1,2-dichloroethene (4.75 g). Product 11 was puri-
fied by column chromatography with hexane as eluent. Yield 3.03 g
(76%) yellow oil (Rf ϭ 0.42 in pentane). Ϫ 1H NMR (400 MHz,
3
CDCl3, 25 °C): δ ϭ 6.08 (d, J ϭ 7.4 Hz, 1 H, 3-CHolef), 6.43 (d,
3J ϭ 7.6 Hz, 1 H, 4-CHolef), 7.33 (m, 3 H, 2-CHar, 2Ј-CHar, 4-
CHar), 7.50 (m, 2 H, 3-CHar, 3Ј-CHar). Ϫ 13C NMR (105.5 MHz,
CDCl3, 25 °C): δ ϭ 83.25 (Cacet-2), 97.40 (Cacet-1), 112.06 (Colef
-
3), 122.67 (Car-1), 128.23 (Colef-4), 128.32 (Car-4), 128.72 (Car-2,
Car-2Ј), 131.65 (Car-3, Car-3Ј). Ϫ IR (NaCl): ν˜ [cmϪ1] ϭ 3083, 3027,
2204, 1953, 1599, 1581, 1489, 1441, 1342, 1264, 1188, 1070, 1028,
984, 916, 806, 756, 722, 690, 636. Ϫ MS (70 eV, EI): m/z (%) ϭ 162
(100) [M]ϩ, 127 (83) [M Ϫ Cl]ϩ.
Figure 7. X-ray crystal structure of compound 27 (hydrogen atoms
and solvent molecules omitted for clarity): a) view of the molecule
plane; b) and c) arrangement of the molecules within the unit cell;
Trimethyl[(3Z)-6-phenylhex-3-ene-1,5-diynyl]silane (12):[17] Com-
pound 12 was synthesized according to general procedure I, with
11 (1.30 g) and TMS-acetylene (1.03 g). Product 12 was isolated by
flash column chromatography, with pentane as eluent. Yield 1.52 g
(84%) yellow oil (Rf ϭ 0.20 in pentane). Ϫ 1H NMR (400 MHz,
CDCl3, 25 °C): δ ϭ 0.24 (s, 9 H, CH3), 5.87 (d, 3J ϭ 11.0 Hz, 1 H,
˚
selected bond lengths [A] and angles [°]: C(20)ϪC(21) 1.410(5),
C(21)ϪC(22) 1.211(5), C(22)ϪC(23) 1.398(5), C(23)ϪC(27)
1.361(5),
C(27)ϪC(28)
1.414(5),
C(28)ϪC(29)
1.195(5),
Si(1)ϪC(29) 1.858(4), Si(1)ϪC(30) 1.850(5), C(23)ϪC(24) 1.535(6),
C(24)ϪC(25) 1.518(8), C(25)ϪC(26) 1.528(7), C(26)ϪC(27)
1.518(6); C(21)ϪC(22)ϪC(23) 176.7(4), C(27)ϪC(23)ϪC(22)
126.7(3), C(23)ϪC(27)ϪC(28) 125.3(4), C(29)ϪC(28)ϪC(27)
179.7(4), C(27)ϪC(23)ϪC(24) 111.1(3), C(23)ϪC(27)ϪC(26)
110.7(3), C(25)ϪC(24)ϪC(23) 105.1(4), C(24)ϪC(25)ϪC(26)
107.2(5), C(27)ϪC(26)ϪC(25) 105.8(4), C(28)ϪC(29)ϪSi(1)
173.9(4), C(30)ϪSi(1)ϪC(29) 106.8(2)
3
3-CHolef), 6.05 (d, J ϭ 10.7 Hz, 1 H, 4-CHolef), 7.32 (m, 3 H, 2-
CHar, 2Ј-CHar, 4-CHar), 7.47 (m, 2 H, 3-CHar, 3Ј-CHar). Ϫ 13C
NMR (105.5 MHz, CDCl3, 25 °C): δ ϭ Ϫ0.12 (CH3), 87.07 (Cacet
-
5), 97.57 (Cacet-6), 102.18 (Cacet-1), 103.35 (Cacet-2), 119.33, 120.67
(Colef-3, Colef-4), 123.04 (Car-1), 128.30 (Car-4), 128.61 (Car-2, Car-
2Ј), 131.77 (Car-3, Car-3Ј). Ϫ IR (NaCl): ν˜ [cmϪ1] ϭ 3056, 2960,
H2SO4 (aq) or with KMnO4 (aq). Ϫ Materials and solvents were 2899, 2195, 2145, 1881, 1715, 1676, 1598, 1489, 1443, 1395, 1251,
obtained from commercial suppliers and were dried and purified
1051, 1027, 999, 961, 845, 757, 690, 633. Ϫ MS (70 eV, EI): m/z
according to literature methods.[31] Products were isolated when- (%) ϭ 224 (68) [M]ϩ, 209 (100) [M Ϫ CH3]ϩ, 193 (14), 165 (15),
ever possible by flash column chromatography (FC) (silica gel 60, 105 (15), 83 (22), 43 (17).
3886
Eur. J. Org. Chem. 2001, 3879Ϫ3890

An Iterative Approach to cis-Oligodiacetylenes
FULL PAPER
[(3Z)-6-Phenylhex-3-ene-1,5-diynyl]benzene (13):[17] Compound 13
was synthesized according to general procedure I, with 11 (0.22 g)
and phenylacetylene (0.14 g). Product 13 was isolated by flash col-
NMR (105.5 MHz, CDCl3, 25 °C): δ ϭ 11.21 [CH(CH3)2], 18.57
[CH(CH3)2], 87.21 (Cacet-9), 94.63, 95.00 (Cacet-5, Cacet-6), 97.94
(Cacet-10), 100.68 (Cacet-1), 103.93 (Cacet-2), 119.15, 119.83, 120.25,
umn chromatography, with hexane as eluent. Yield 0.26 g (87%) 120.34 (Colef-3, Colef-4, Colef-7, Colef-8), 123.04 (Car-1), 128.28 (Car-
yellow solid (Rf ϭ 0.16 in pentane). Ϫ 1H NMR (400 MHz, CDCl3,
˜
4), 128.59 (Car-2, Car-2Ј), 131.86 (Car-3, Car-3Ј). Ϫ IR (NaCl): ν
25 °C): δ ϭ 6.10 (s, 2 H, 3-CHolef, 4-CHolef), 7.33 (m, 6 H, 2 ϫ 2- [cmϪ1] ϭ 33042, 2943, 2890, 2865, 2197, 2137, 1673, 1598, 1489,
CHar, 2Ј-CHar, 4-CHar), 7.52 (m, 4 H, 2 ϫ 3-CHar, 3Ј-CHar). Ϫ 13C 1463, 1406, 1384, 1240, 1136, 1071, 1022, 997, 918, 883, 754, 678.
NMR (105.5 MHz, CDCl3, 25 °C): δ ϭ 87.29 (Cacet-2, Cacet-5), Ϫ UV/Vis (cyclohexane): λmax [nm] ϭ 227.0, 275.0, 344.0, 368.5.
97.57 (Cacet-1, Cacet-6), 119.42 (Colef-3, Colef-4), 123.10 (2 ϫ Car-1), Ϫ MS (70 eV, EI): m/z (%) ϭ 358 (64) [M]ϩ, 315 (100) [M Ϫ
128.36 (2 ϫ Car-4), 128.61 (2 ϫ Car-2, Car-2Ј), 131.66 (2 ϫ Car-3,
C3H7]ϩ, 272 (72) [315 Ϫ C3H7]ϩ, 257 (23) [272 Ϫ CH3]ϩ, 245 (44),
Car-3Ј). Ϫ IR (NaCl): ν [cmϪ1] ϭ 3080, 3058, 2216, 2180, 1713, 238 (51), 202 (22), 129 (35), 99 (27), 69 (19), 57 (37), 43 (36).
˜
1674, 1597, 1572, 1488, 1441, 1401, 1263, 1176, 1157, 1069, 1030,
[(3Z,7Z)-10-Phenyldeca-3,7-diene-1,5,9-triynyl]benzene (17): Gen-
996, 915, 757, 689. Ϫ UV/Vis (CH2Cl2): λmax (ε) [nm] ϭ 257.5
eral procedure II was carried out, with 12 (0.15 g) and K2CO3
(23400), 328.5 (26625), 352.0 (17875). Ϫ MS (70 eV, EI): m/z (%) ϭ
(0.74 g). The crude product was used in the next step according to
228 (100) [M]ϩ, 126 (25), 28 (27). Ϫ C18H12 (228.29): calcd. C
general procedure I, with 11 (0.13 g). The product 17 was isolated
94.70, H 5.30; found C 94.09, H 5.74; m.p. 34 °C.
by flash column chromatography, with pentane as eluent. Yield
[(3Z,7Z)-8-Chloroocta-3,7-diene-1,5-diynyl]benzene (14): General 0.05 g (29%) brownish oil (Rf ϭ 0.09 in pentane). Ϫ 1H NMR
procedure II was carried out, with 12 (0.80 g) and K2CO3 (3.72 g).
(400 MHz, CDCl3, 25 °C): δ ϭ 6.14 (s, 4 H, CHolef), 7.20Ϫ7.53 (m,
The crude product was used in the next step according to general 10 H, CHar). Ϫ 13C NMR (105.5 MHz, CDCl3, 25 °C): δ ϭ 87.23
procedure I, with (Z)-1,2-dichloroethene (0.66 g). Product 14 was
isolated by flash column chromatography, with hexane/chloroform
(10:1) as eluent. Yield 0.32 g (42%) yellow solid (Rf ϭ 0.38 in pent-
(Cacet-2, Cacet-9), 94.98 (Cacet-5, Cacet-6), 98.27 (Cacet-1, Cacet-10),
118.98, 119.97 (Colef-3, Colef-4, Colef-7, Colef-8), 122.89 (2 ϫ Car-1),
128.14 (2 ϫ Car-4), 128.50 (2 ϫ Car-2, Car-2Ј), 131.92 (2 ϫ Car-3,
ane/chloroform ϭ 10:1). Ϫ 1H NMR (400 MHz, CDCl3, 25 °C): Car-3Ј). Ϫ IR (NaCl): ν [cmϪ1] ϭ 3034, 2925, 2192, 2164, 1675,
δ ϭ 6.09 (m, 3 H, 3-CHolef, 4-CHolef, 7-CHolef), 6.45 (d, 3J ϭ 1598, 1489, 1442, 1408, 1130, 1070, 1029, 932, 915, 757, 689. Ϫ
7.3 Hz, 1 H, 8-CHolef), 7.31 (m, 3 H, 2-CHar, 2Ј-CHar, 4-CHar), 7.47 MS (70 eV, EI): m/z (%) ϭ 278 (58) [M]ϩ, 276 (100), 228 (12), 226
(m, 2 H, 3-CHar, 3Ј-CHar). Ϫ 13C NMR (105.5 MHz, CDCl3, 25 (13), 138 (17). Ϫ C22H14 (278.35): calcd. C 94.93, H 5.07; found C
˜
°C): δ ϭ 87.01 (Cacet-2), 90.92 (Cacet-6), 94.92 (Cacet-5), 98.14 (Cacet
-
92.78, H 5.00.
1), 112.06 (Colef-7), 118.66, 120.52 (Colef-3, Colef-4), 122.95 (Car-1),
128.27 (Car-4), 128.65 (Car-2, Car-2Ј), 129.20 (Colef-8), 132.01 (Car-
[(3Z,7Z,11Z)-14-Phenyltetradeca-3,7,11-triene-1,5,9,13-
tetraynyl]benzene (18): General procedure II was carried out, with
12 (0.34 g) and K2CO3 (1.68 g). The crude product was used in the
next step according to general procedure I, with (Z)-1,2-dichloroe-
thene (0.06 g). Product 18 was isolated first by flash column chro-
matography, with pentane/chloroform (12:1) as eluent, and then by
preparative HPLC, with heptane/dichloromethane (95:5) as eluent.
Yield 0.03 g (6%) yellow solid (Rf ϭ 0.21 in pentane/chloroform ϭ
12:1). Ϫ 1H NMR (400 MHz, CDCl3, 25 °C): δ ϭ 5.94 (d, 3J ϭ
3, Car-3Ј). Ϫ IR (NaCl): ν [cmϪ1] ϭ 3082, 2199, 2176, 1677, 1597,
˜
1554, 1489, 1442, 1400, 1332, 1268, 1217, 1130, 1070, 1028, 981,
916, 857, 783, 756, 723, 690, 670. Ϫ UV/Vis (CH2Cl2): λmax (ε)
[nm] ϭ 248.5 (48670), 261.0 (46940), 272.5 (25020), 290.0 (38540),
308.0 (56700), 329.0 (50350), 348.5 (2985). Ϫ MS (70 eV, EI): m/z
(%) ϭ 212 (100) [M]ϩ, 176 (90) [M Ϫ Cl]ϩ, 151 (29). Ϫ C14H9Cl
(212.68): calcd. C 79.06, H 4.91; found C 84.81, H 5.38; m.p. 76 °C.
3
Triisopropyl[(3Z)-6-phenylhex-3-ene-1,5-diynyl]silane (15): Com-
12.0 Hz, 2 H, 3-CHolef, 12-CHolef), 6.70 (d, J ϭ 12.0 Hz, 2 H, 4-
pound 15 was synthesized according to general procedure I, with CHolef, 11-CHolef), 7.32 (m, 6 H, 2 ϫ 2-CHar, 2Ј-CHar, 4-CHar), 7.48
11 (1.56 g) and TIPS-acetylene (2.10 g). Product 15 was isolated by
flash column chromatography, with hexane as eluent. Yield 2.80 g
(94%) yellowish oil (Rf ϭ 0.45 in pentane). Ϫ 1H NMR (400 MHz,
(m, 4 H, 2 ϫ 3-CHar, 3Ј-CHar), 7.96 (s, 2 H, 7-CHolef, 8-CHolef). Ϫ
13C NMR (105.5 MHz, CDCl3, 25 °C): δ ϭ 88.51, 88.99, 92.48
(Cacet-2, Cacet-5, Cacet-6, Cacet-9, Cacet-10, Cacet-13), 96.49 (Cacet-1,
CDCl3, 25 °C): δ ϭ 1.10 [s, 21 H, CH(CH3)2], 5.90 (d, 3J ϭ 11.0 Hz, Cacet-14), 107.80 (Colef-3, Colef-12), 123.41 (2 ϫ Car-1), 128.39 (2 ϫ
1 H, 3-CHolef), 6.05 (d, 3J ϭ 10.5 Hz, 1 H, 4-CHolef), 7.30 (m, 3 H, Car-4), 128.43 (2 ϫ Car-2, Car-2Ј), 128.67 (Colef-7, Colef-8), 131.43
2-CHar, 2Ј-CHar, 4-CHar), 7.45 (m, 2 H, 3-CHar, 3Ј-CHar). Ϫ 13C (2 ϫ Car-3, Car-3Ј), 138.09 (Colef-4, Colef-11). Ϫ IR (KBr): ν
˜
NMR (105.5 MHz, CDCl3, 25 °C): δ ϭ 11.26 [CH(CH3)2], 18.64 [cmϪ1] ϭ 3619, 2956, 2189, 1598, 1489, 1441, 1250, 1069, 1028,
[CH(CH3)2], 87.09 (Cacet-5), 97.16 (Cacet-6), 99.94 (Cacet-1), 103.97 952, 913, 838, 755, 689. Ϫ UV/Vis (CH2Cl2): λmax (ε) [nm] 235.0
(Cacet-2), 119.46, 120.17 (Colef-3, Colef-4), 123.08 (Car-1), 128.20 (21330), 350.0 (32015). Ϫ MS (FAB): m/z ϭ 330 [M ϩ 2 H]ϩ, 252
(Car-4), 128.49 (Car-2, Car-2Ј), 131.71 (Car-3, Car-3Ј). Ϫ IR (NaCl): [330 Ϫ C6H6]ϩ. Ϫ C26H16 (328.41): calcd. C 95.09, H 4.91; found
ν˜ [cmϪ1] ϭ 2943, 2891, 2865, 2194, 2141, 1676, 1598, 1568, 1489,
1463, 1394, 1366, 1050, 1017, 997, 953, 918, 883, 784, 755, 678. Ϫ
UV/Vis (CH2Cl2): λmax (ε) [nm] ϭ 261.0 (7500), 307.0 (22670),
327.0 (21410). Ϫ MS (70 eV, EI): m/z (%) ϭ 308 (43) [M]ϩ, 265
(100) [M Ϫ C3H7]ϩ, 237 (21), 223 (24), 195 (40), 104 (33), 59 (20).
Ϫ C21H28Si (308.54): calcd. C 81.75, H 9.15; found C 81.18, H 9.09.
C 92.74, H 5.63; m.p. 175 °C.
(7Z)-Tetradec-7-ene-5,9-diyne (19):[18] Compound 19 was synthe-
sized according to general procedure I, with 1-hexyne (0.35 g) and
(Z)-1,2-dichloroethene (0.21 g). Product 19 was isolated by flash
column chromatography, with pentane as eluent. Yield 0.32 g (80%)
1
yellow oil (Rf ϭ 0.27 in pentane). Ϫ H NMR (400 MHz, CDCl3,
3
Triisopropyl[(3Z,7Z)-10-phenyldeca-3,7-diene-1,5,9-triynyl]silane 25 °C): δ ϭ 0.90 (t, 6 H, J ϭ 7.2 Hz, 1-CH3, 14-CH3), 1.48 (m, 8
3
(16): Compound 15 was synthesized according to general proced-
ure I, with 14 (0.32 g) and TIPS-acetylene (0.41 g). Product 16 was
isolated by flash column chromatography, with hexane/chloroform
H, 2-CH2, 3-CH2, 12-CH2, 13-CH2), 2.37 (t, J ϭ 6.8 Hz, 4-CH2,
11-CH2), 5.70 (s, H, 7-CHolef 8-CHolef).
2
,
Ϫ
13C NMR
(105.5 MHz, CDCl3, 25 °C): δ ϭ 13.60 (CH3-1, CH3-14), 19.43
(CH2-4, CH2-11), 21.88 (CH2-2, CH2-13), 30.70 (CH2-3, CH2-12),
(10:1) as eluent. Yield 0.79 g (41%) yellow oil (Rf ϭ 0.23 in hexane/
1
chloroform ϭ 15:1). Ϫ H NMR (400 MHz, CDCl3, 25 °C): δ ϭ 78.28 (Cacet-6, Cacet-9), 97.83 (Cacet-5, Cacet-10), 118.93 (Colef-7,
1.08 [s, 21 H, CH(CH3)2], 5.89Ϫ6.11 (m, 4 H, CHolef), 7.31 (m, 3
Colef-8). Ϫ IR (NaCl): ν˜ [cmϪ1] ϭ 3026, 2958, 2932, 2872, 2218,
H, 2-CHar, 2Ј-CHar, 4-CHar), 7.46 (m, 2 H, 3-CHar, 3Ј-CHar). Ϫ 13C 1677, 1577, 1466, 1429, 1398, 1379, 1326, 1250, 1161, 1107, 745. Ϫ
Eur. J. Org. Chem. 2001, 3879Ϫ3890
3887

C. Kosinski, A. Hirsch, F. W. Heinemann, F. Hampel
FULL PAPER
UV/Vis (CH2Cl2): λmax (ε) [nm] ϭ 263.5 (11950), 277.5 (11320). Ϫ (2.49 g) and K2CO3 (7.81 g). The crude product was used in the
MS (70 eV, EI): m/z (%) ϭ 188 (92) [M]ϩ, 145 (27) [M Ϫ C3H7]ϩ, next step according to general procedure I, with 1,2-dibromocyclo-
131 (93), 117 (100), 105 (31), 103 (31), 91 (97), 79 (25), 77 (48), 65 pentene (2.55 g). Product 24 was isolated by flash column chroma-
(20), 63 (24), 57 (23), 51 (27), 43 (28), 41 (53), 39 (35), 29 (21),
27 (30).
tography, with hexane/dichloromethane (5:1) as eluent. Yield 0.90 g
(36%) yellow solid (Rf ϭ 0.43 in hexane/dichloromethane, 5:1). Ϫ
1H NMR (400 MHz, CDCl3, 25 °C): δ ϭ 1.99 (2 ϫ quint, 4 H,
[(2-Bromocyclopent-1-en-1-yl)ethynyl]benzene (21) and {[2-(Phenyle-
thynyl)cyclopent-1-en-1-yl]ethynyl}benzene (22): Compounds 21 and
22 were synthesized according to general procedure I, with phenyl-
acetylene (3.19 g) and 1,2-dibromocyclopentene (7.77 g). Products
21 and 22 were purified by column chromatography, with a mixture
of hexane/dichloromethane (15:1) as eluent. Yield 21 6.18 g (80%)
yellow oil (Rf ϭ 0.55 in hexane/dichloromethane, 15:1), 22 1.19 g
(20%) white solid (Rf ϭ 0.28 in hexane/dichloromethane, 15:1).
3
3J ϭ 7.6 Hz, CH2-b, CH2-e), 2.55 (m, 2 H, CH2-d), 2.65 (t, J ϭ
7.6 Hz, 4 H, CH2-a, CH2-c), 2.74 (t, 3J ϭ 7.6 Hz, 2 H, CH2-f), 7.29
(m, 3 H, 2-CHar, 2Ј-CHar, 4-CHar), 7.48 (m, 2 H, 3-CHar, 3Ј-CHar).
Ϫ
13C NMR (105.5 MHz, CDCl3, 25 °C): δ ϭ 22.54 (CH2-e), 23.20
(CH2-b), 35.95 (CH2-d), 36.90, 37.10 (CH2-a, CH2-c), 40.46 (CH2-
f), 86.30 (Cacet-2), 91.87, 92.04 (Cacet-5, Cacet-6), 96.84 (Cacet-1),
123.42 (CHar-1), 124.37 (Colef-8), 128.17 (CHar-4), 128.25 (CHar-2,
CHar-2Ј), 130.00, 130.81 (Colef-3, Colef-4, Colef-7), 131.85 (CHar-3,
Compound 21: 1H NMR (400 MHz, CDCl3, 25 °C): δ ϭ 2.02
CHar-3Ј). Ϫ IR (KBr): ν [cmϪ1] ϭ 3442, 2923, 2851, 2197, 1715,
˜
3
3
(quint, 2 H, J ϭ 7.6 Hz, CH2-b), 2.57 (t, J ϭ 7.6 Hz, 2 H, CH2-
a), 2.76 (t, 3J ϭ 7.6 Hz, 2 H, CH2-c), 7.34 (m, 3 H, 2-CHar, 2Ј-CHar,
4-CHar), 7.50 (m, 2 H, 3-CHar, 3Ј-CHar). Ϫ 13C NMR (105.5 MHz,
CDCl3, 25 °C): δ ϭ 22.50 (CH2-b), 35.88 (CH2-a), 40.35 (CH2-c),
84.89 (Cacet-2), 95.25 (Cacet-1), 123.08 (Car-1), 124.19 (Colef-4),
127.77 (Colef-3), 128.27 (CHar-4), 128.36 (CHar-2, CHar-2Ј), 131.61
1595, 1488, 1439, 1362, 1312, 1289, 1203, 1119, 1084, 1070, 1025,
970, 918, 878, 810, 756, 694, 591, 534, 500, 439. Ϫ UV/Vis
(CH2Cl2): λmax (ε) [nm] ϭ 262.5 (17132), 334.0 (18140). Ϫ MS
(70 eV, EI): m/z (%) ϭ 338 (100) [M81Br]ϩ, 336 (100) [M79Br]ϩ, 256
(17) [M Ϫ Br]ϩ, 241 (32), 229 (36), 215 (25), 202 (17), 115 (20), 85
(19), 71 (29), 57 (51), 43 (40). Ϫ C20H17Br (337.26): calcd. C 71.23,
H 5.08; found C 70.93, H 5.13; m.p. 71 °C.
(CHar-3, CHar-3Ј). Ϫ IR (NaCl): ν [cmϪ1] ϭ 3060, 2954, 2851,
˜
2218, 2203, 2151, 1594, 1487, 1442, 1319, 1069, 1026, 931, 755,
689. Ϫ UV/Vis (CH2Cl2): λmax (ε) [nm] ϭ 285.5 (31960), 303.5
(25300), 329.0 (3910). Ϫ MS (70 eV, EI): m/z (%) ϭ 248 (83)
[M81Br]ϩ, 246 (84) [M79Br]ϩ, 167 (87), 165 (100), 152 (72), 139
(29), 83 (30), 82 (30), 43 (25). Ϫ C13H11Br (247.13): calcd. C 63.18,
H 4.49; found C 59.64, H 4.20.
Trimethyl[(2-{[2-(phenylethynyl)cyclopent-1-en-1-yl]ethynyl}-
cyclopent-1-en-1-yl)ethynyl]silane (25): Compound 25 was synthe-
sized according to general procedure I, with 24 (0.65 g) and TMS-
acetylene (0.75 g). Product 25 was isolated by flash column chro-
matography, with hexane/dichloromethane (10:1) as eluent. Yield
0.67 g (99%) yellowish solid (Rf ϭ 0.18 in hexane/dichloromethane,
10:1). Ϫ 1H NMR (400 MHz, CDCl3, 25 °C): δ ϭ 0.15 [s, 9 H,
Compound 22: 1H NMR (400 MHz, CDCl3, 25 °C): δ ϭ 2.02
3
3
(quint, 2 H, J ϭ 7.6 Hz, CH2-b), 2.69 (t, J ϭ 7.6 Hz, 4 H, CH2-
a, CH2-c), 7.31 (m, 6 H, 2 ϫ 2-CHar, 2Ј-CHar, 4-CHar), 7.51 (m, 4
H, 2 ϫ 3-CHar, 3Ј-CHar). Ϫ 13C NMR (105.5 MHz, CDCl3, 25 °C):
δ ϭ 23.18 (CH2-b), 36.99 (CH2-a, CH2-c), 86.30 (Cacet-2, Cacet-5),
96.64 (Cacet-1, Cacet-6), 123.41 (2 ϫ Car-1), 128.25 (2 ϫ CHar-4),
128.28 (2 ϫ CHar-2, CHar-2Ј), 130.31 (Colef-3, Colef-4), 131.59 (2 ϫ
3
Si(CH3)3], 1.95 (2 ϫ quint, 4 H, J ϭ 7.7 Hz, CH2-b, CH2-e), 2.63
(m, 8 H, CH2-a, CH2-c, CH2-d, CH2-f), 7.28 (m, 3 H, 2-CHar, 2Ј-
CHar, 4-CHar), 7.44 (m, 2 H, 3-CHar, 3Ј-CHar). Ϫ 13C NMR
(105.5 MHz, CDCl3, 25 °C): δ ϭ 0.01 [Si(CH3)3], 23.18 (CH2-b,
CH2-e), 36.99, 37.08, 37.12, 37.21 (CH2-a, CH2-c, CH2-d, CH2-f),
86.43 (Cacet-2), 93.11, 93.37 (Cacet-5 and Cacet-6), 96.82 (Cacet-1),
101.57 (Cacet-10), 102.23 (Cacet-9), 123.50 (CHar-1), 128.17 (CHar-
CHar-3, CHar-3Ј). Ϫ IR (KBr): ν [cmϪ1] ϭ 3077, 2925, 2851, 2359,
˜
2184, 1596, 1487, 1439, 1363, 1277, 1155, 1066, 1027, 989, 915,
839, 755, 689, 591, 528, 447, 431. Ϫ UV/Vis (CH2Cl2): λmax (ε)
[nm] ϭ 229.5 (19180), 261.5 (24642), 332.0 (23645), 356.0 (14194).
Ϫ MS (70 eV, EI): m/z (%) ϭ 268 (100) [M]ϩ, 252 (38) [M Ϫ CH2]ϩ.
Ϫ C21H16 (268.36): calcd. C 93.99, H 6.01; found C 93.27, H 5.86;
m.p. 87 °C.
4), 128.25 (CHar-2, CHar-2Ј), 130.07, 130.18, 130.40 (Colef-3, Colef
-
˜
4, Colef-7, Colef-8), 131.77 (CHar-3, CHar-3Ј). Ϫ IR (KBr): ν
[cmϪ1] ϭ 3442, 2955, 2924, 2853, 2130, 1600, 1488, 1442, 1374,
1253, 1241, 1069, 1027, 968, 916, 844, 750, 687, 621, 563, 524, 438.
Ϫ UV/Vis (CH2Cl2): λmax (ε) [nm] ϭ 231.0 (10347), 281.5 (9396),
351.5 (13001), 377.0 (8619). Ϫ MS (70 eV, EI): m/z (%) ϭ 354 (100)
[M]ϩ, 339 (33) [M Ϫ CH3]ϩ, 311 (27), 295 (52), 279 (42), 265 (23),
252 (22), 73 (91), 59 (49). Ϫ C25H26Si (354.56): calcd. C 84.69, H
7.39; found C 83.41, H 7.53; m.p. 101 °C.
Trimethyl{[2-(phenylethynyl)cyclopent-1-en-1-yl]ethynyl}silane (23):
Compound 23 was synthesized according to general procedure I,
with 21 (6.00 g) and TMS-acetylene (9.53 g). Product 23 was isol-
ated by flash column chromatography, with hexane/dichlorome-
thane (20:1) as eluent. Yield 5.84 g (91%) yellowish solid (Rf ϭ 0.24
{[2-({2-[(2-Bromocyclopent-1-en-1-yl)ethynyl]cyclopent-1-en-1-yl}-
ethynyl)cyclopent-1-en-1-yl]ethynyl}benzene (26): General procedure
II was carried out, with 25 (0.77 g) and K2CO3 (1.93 g). The crude
product was used in the next step according to general procedure
I, with 1,2-dibromocyclopentene (0.54 g). Product 26 was isolated
by flash column chromatography, with hexane/dichloromethane
(5:1) as eluent. Yield 0.90 g (36%) yellow-brownish solid (Rf ϭ 0.36
in hexane/dichloromethane, 5:1). Ϫ 1H NMR (400 MHz, CDCl3,
1
in hexane/dichloromethane, 20:1). Ϫ H NMR (400 MHz, CDCl3,
3
25 °C): δ ϭ 0.23 [s, 9 H, Si(CH3)3], 1.94 (quint, 2 H, J ϭ 7.6 Hz,
CH2-b), 2.60 (m, 4 H, CH2-a, CH2-c), 7.30 (m, 3 H, 2-CHar, 2Ј-
CHar, 4-CHar), 7.45 (m, 2 H, 3-CHar, 3Ј-CHar). Ϫ 13C NMR
(105.5 MHz, CDCl3, 25 °C): δ ϭ 0.03 [Si(CH3)3], 23.14 (CH2-b),
36.79 (CH2-a, CH2-c), 86.08 (Cacet-2), 96.71 (Cacet-3), 101.54 (Cacet
-
6), 101.98 (Cacet-5), 123.37 (Car-1), 128.26 (CHar-4), 128.35 (CHar-
2, CHar-2Ј), 130.31 (Colef-3), 131.65 (CHar-3, CHar-3Ј), 131.75
(Colef-4). Ϫ IR (KBr): ν˜ [cmϪ1] ϭ 2959, 2850, 2139, 1600, 1489,
1442, 1350, 1250, 1130, 1069, 1028, 995, 913, 844, 756, 690. Ϫ UV/
Vis (CH2Cl2): λmax (ε) [nm] ϭ 239.0 (19627), 311.0 (28857), 332.0
(24389). Ϫ MS (70 eV, EI): m/z (%) ϭ 264 (100) [M]ϩ, 249 (85). Ϫ
C18H20Si (264.44): calcd. C 81.76, H 7.62; found C 82.28, H 7.83;
m.p. 46 °C.
3
3
25 °C): δ ϭ 1.76 (quint, 2 H, J ϭ 7.6 Hz, CH2-h), 1.91 (t, J ϭ
7.6 Hz, 4 H, CH2-b, CH2-e), 2.35 (t, 3J ϭ 7.6 Hz, 2 H, CH2-g).
2.58 (t, 10 H, J ϭ 7.6 Hz, CH2-a, CH2-c, CH2-d, CH2-f, CH2-i),
3
7.22 (m, 3 H, 2-CHar, 2Ј-CHar, 4-CHar), 7.39 (m, 2 H, 3-CHar, 3Ј-
CHar). Ϫ 13C NMR (105.5 MHz, CDCl3, 25 °C): δ ϭ 22.36 (CH2-
h), 23.18 (CH2-b, CH2-e), 35.91 (CH2-g), 37.06, 37.17, 37.30 (CH2-
a, CH2-c, CH2-d, CH2-f), 40.37 (CH2-i), 86.54 (Cacet-2), 92.09,
({2-[(2-Bromocyclopent-1-en-1-yl)ethynyl]cyclopent-1-en-1-yl}- 92.18, 93.33, 93.59 (Cacet-5, Cacet-6, Cacet-9, Cacet-10), 96.84 (Cacet
-
ethynyl)benzene (24): General procedure II was carried out, with 23
1), 123.42 (CHar-1), 124.47 (Colef-12), 127.92 (Colef-11), 128.06
3888
Eur. J. Org. Chem. 2001, 3879Ϫ3890

An Iterative Approach to cis-Oligodiacetylenes
FULL PAPER
(CHar-4), 128.16 (CHar-2, CHar-2Ј), 129.98, 130.37, 130.40, 130.68 eluent. Yield 0.23 g (87%) yellow oil (Rf ϭ 0.42 in hexane/dichloro-
1
(Colef-3, Colef-4, Colef-7, Colef-8), 131.81 (CHar-3, CHar-3Ј). Ϫ IR methane, 10:1). Ϫ H NMR (400 MHz, CDCl3, 25 °C): δ ϭ 1.00
(KBr): ν [cmϪ1] ϭ 3474, 2963, 2952, 2922, 2849, 2183, 2156, 1735, (t, 6 H, 3J ϭ 7.3 Hz, CH3Ϫ1, CH3Ϫ12), 1.55 (sextet, 4 H, 3J ϭ 7.1,
˜
1604, 1488, 1442, 1378, 1312, 1281, 1210, 1083, 1028, 909, 753, 688, 3J ϭ 7.3 Hz, CH2Ϫ2, CH2Ϫ11), 1.85 (quint, 2 H, 3J ϭ 7.6 Hz, CH2-
594, 523, 417. Ϫ UV/Vis (CH2Cl2): λmax (ε) [nm] ϭ 300.5 (26250),
364.0 (24360). Ϫ MS (70 eV, EI): m/z (%) ϭ 428 (78) [M81Br]ϩ, 426 4 H, CH2-a, CH2-c). Ϫ 13C NMR (105.5 MHz, CDCl3, 25 °C): δ ϭ
(76) [M79Br]ϩ, 347 [M Ϫ Br]ϩ, (100), 317 (16), 303 (19), 294 (30).
13.38 (CH3-1, CH3-12), 21.75 (CH2-3, CH2-10), 22.17 (CH2-2,
Ϫ C27H23Br (427.38): calcd. C 75.88, H 5.42; found C 74.73, H CH2-11), 22.87 (CH2-b), 36.90 (CH2-a, CH2-c), 77.53 (Cacet-5,
b), 2.35 (t, 3J ϭ 7.1 Hz, 4 H, 3-CH2, 10-CH2), 2.46 (t, 3J ϭ 7.6 Hz,
5.44; m.p. 119 °C.
Cacet-8), 96.60 (Cacet-4, Cacet-9), 129.09 (Colef-6, Colef-7). Ϫ IR (NaCl):
ν˜ [cmϪ1] ϭ 2962, 2934, 2871, 2213, 1458, 1380, 1353, 1276. Ϫ UV/
Vis (CH2Cl2): λmax (ε) [nm] ϭ 268.0 (16369), 281.5 (14217). Ϫ MS
(70 eV, EI): m/z (%) ϭ 200 (100) [M]ϩ, 171 (25) [M Ϫ C2H5]ϩ, 157
(10) [171 Ϫ CH2]ϩ, 143 (15) [157 Ϫ CH2]ϩ, 129 (25) [143 Ϫ CH2]ϩ,
115 (13) [129 Ϫ CH2]ϩ, 91 (11). Ϫ C15H20 (200.32): calcd. C 89.94,
H 10.06; found C 88.91, H 9.99.
Trimethyl({2-[(2-{[2-(phenylethynyl)cyclopent-1-en-1-yl]ethynyl}-
cyclopent-1-en-1-yl)ethynyl]cyclopent-1-en-1-yl}ethynyl)silane (27):
Compound 27 was synthesized according to general procedure I,
with 26 (0.09 g) and TMS-acetylene (0.12 g). Product 27 was isol-
ated by flash column chromatography, with hexane/dichlorome-
thane (5:1) as eluent. Yield 0.07 g (81%) orange solid (Rf ϭ 0.42 in
1
[(2-Bromocyclopent-1-en-1-yl)ethynyl](trimethyl)silane (30) and
Trimethyl({2-[(trimethylsilyl)ethynyl]cyclopent-1-en-1-yl}ethynyl)-
silane (31): Compounds 30 and 31 were synthesized according to
general procedure I, with TMS-acetylene (0.33 g) and 1,2-dibromo-
cyclopentene (0.76 g). Products 30 and 31 were purified by column
chromatography, with a mixture of hexane/dichloromethane (20:1)
as eluent. Yield 30 0.36 g (44%) yellow oil (Rf ϭ 0.49 in hexane),
31 0.18 g (21%) yellowish solid (Rf ϭ 0.22 in hexane).
hexane/dichloromethane, 5:1). Ϫ H NMR (400 MHz, CDCl3, 25
°C): δ ϭ 0.20 [s, 9 H, Si(CH3)3], 1.70 (quint, 2 H, 3J ϭ 7.6 Hz,
CH2-h), 1.96 (quint, 4 H, 3J ϭ 7.6 Hz, CH2-b, CH2-e), 2.43 (t, 3J ϭ
7.6 Hz, 4 H, CH2-g, CH2-i), 2.63 (m, 8 H, CH2-a, CH2-c, CH2-d,
CH2-f), 7.27 (m, 3 H, 2-CHar, 2Ј-CHar, 4-CHar), 7.44 (m, 2 H, 3-
CHar, 3Ј-CHar). Ϫ 13C NMR (105.5 MHz, CDCl3, 25 °C): δ ϭ
0.00 [Si(CH3)3], 22.93(CH2-h), 23.13 (CH2-b, CH2-e), 36.79, 36.93
(CH2-g, CH2-i), 37.03, 37.10, 37.25, 37.38 (CH2-a, CH2-c, CH2-d,
CH2-f), 86.44 (Cacet-2), 93.41, 93.49 (Cacet-5, Cacet-6, Cacet-9, Cacet
-
1
Compound 30: H NMR (400 MHz, CDCl3, 25 °C): δ ϭ 0.20 [s, 9
10), 96.83 (Cacet-1), 101.67 (Cacet-14), 101.93 (Cacet-13), 123.35
(CHar-1), 128.01 (CHar-4), 128.12 (CHar-2, CHar-2Ј), 129.90,
130.03, 130.16, 130.33 (Colef-3, Colef-4, Colef-7, Colef-8, Colef-11),
131.82 (CHar-3, CHar-3Ј), 132.04 (Colef-12). Ϫ IR (KBr): ν˜
[cmϪ1] ϭ 3442, 2957, 2926, 2852, 2131, 1718, 1636, 1489, 1443,
1385, 1249, 1177, 1095, 845, 756, 687. Ϫ UV/Vis (CH2Cl2): λmax
(ε) [nm] ϭ 264.0 (23960), 302.5 (30650), 316.0 (41225), 364.5
(34085), 465.5 (3560). Ϫ MS (70 eV, EI): m/z (%) ϭ 444 (100) [M]ϩ,
371 (17) [M Ϫ TMS]ϩ, 73 (65). Ϫ C32H32Si (444.69): calcd. C
86.43, H 7.25; found C 83.53, H 7.08; m.p. 169 °C.
3
3
H, Si(CH3)3], 1.95 (quint, 2 H, J ϭ 7.6 Hz, CH2-b), 2.46 (t, J ϭ
7.6 Hz, 2 H, CH2-a), 2.68 (t, 3J ϭ 7.6 Hz, 2 H, CH2-c). Ϫ 13C
NMR (105.5 MHz, CDCl3, 25 °C): δ ϭ 22.46 (CH2-b), 35.84 (CH2-
a), 40.31 (CH2-c), 100.15 (Cacet-1), 101.00 (Cacet-2), 124.23 (Colef
-
4), 128.81 (Colef-3). Ϫ IR (NaCl): ν [cmϪ1] ϭ 2960, 2854, 2150,
1720, 1609, 1441, 1311, 1250, 1039, 936, 844, 760, 700. Ϫ MS
(70 eV, EI): m/z (%) ϭ 244 (27) [M81Br]ϩ, 242 (26) [M79Br]ϩ, 229
(100) [M81Br Ϫ CH3]ϩ, 227 (97) [M79Br Ϫ CH3]ϩ, 147 (35), 145
(26), 139 (34), 137 (34), 105 (46), 74 (22), 43 (20).
˜
Compound 31: 1H NMR (400 MHz, CDCl3, 25 °C): δ ϭ 0.19 [s, 18
3
3
({2-[(2-{[2-(Phenylethynyl)cyclopent-1-en-1-yl]ethynyl}cyclopent-1-
en-1-yl)ethynyl]cyclopent-1-en-1-yl}ethynyl)benzene (28): General
procedure II was carried out, with 23 (1.60 g) and K2CO3 (4.93 g).
The crude product was used in the next step according to general
procedure I, with 1,2-dibromocyclopentene (0.62 g). Product 28
was isolated by flash column chromatography, with hexane/dichlor-
omethane (5:1) as eluent. Yield 0.11 g (9%) bright brownish solid
H, Si(CH3)3], 1.87 (quint, 2 H, J ϭ 7.6 Hz, CH2-b), 2.51 (t, J ϭ
7.6 Hz, 4 H, CH2-a, CH2-c). Ϫ 13C NMR (105.5 MHz, CDCl3, 25
°C): δ ϭ 0.03 [Si(CH3)3], 23.11 (CH2-b), 36.65 (CH2-a, CH2-c),
101.20 (Cacet-1, Cacet-6), 102.06 (Cacet-2, Cacet-5), 131.74 (Colef-3,
Colef-4). Ϫ IR (KBr): ν [cmϪ1] ϭ 2961, 2924, 2852, 2193, 2135,
˜
1442, 1408, 1330, 1249, 1180, 1015, 844, 758, 698, 618, 556, 478.
Ϫ UV/Vis (CH2Cl2): λmax (ε) [nm] ϭ 282.5 (23252), 297.5 (22011).
Ϫ MS (70 eV, EI): m/z (%) ϭ 260 (80) [M]ϩ, 245 (78) [M Ϫ CH3]ϩ,
171 (45), 157 (18), 115 (35), 73 (100), 59 (21), 45 (25). Ϫ C15H24Si2
(260.53): calcd. C 69.15, H 9.26; found C 68.87, H 9.34; m.p. 39 °C.
(Rf
ϭ 0.18 in hexane/dichloromethane, 5:1). Ϫ
1H NMR
(400 MHz, CDCl3, 25 °C): δ ϭ 1.73 (quint, 4 H, 3J ϭ 7.6 Hz, CH2-
3
b, CH2-h), 1.92 (quint, 2 H, J ϭ 7.6 Hz, CH2-e), 2.46 (2 ϫ tr, 8
H, 3J ϭ 7.6 Hz, CH2-a, CH2-c, CH2-g, CH2-i), 2.61 (t, 3J ϭ 7.6 Hz,
4 H, CH2-d, CH2-f), 7.22 (m, 6 H, 2 ϫ 2-CHar, 2Ј-CHar, 4-CHar),
7.40 (m, 4 H, 2 ϫ 3-CHar, 3Ј-CHar). Ϫ 13C NMR (105.5 MHz,
CDCl3, 25 °C): δ ϭ 22.99 (CH2-b, CH2-h), 23.23 (CH2-e), 36.99,
37.04 (CH2-a, CH2-c, CH2-g, CH2-i), 37.32 (CH2-d, CH2-h), 86.61
(Cacet-2, Cacet-13), 93.50, 93.83 (Cacet-5, Cacet-6, Cacet-9, Cacet-10),
96.84 (Cacet-1, Cacet-14), 123.53 (2 ϫ Car-1), 128.00 (2 ϫ CHar-4),
128.14 (2 ϫ CHar-2, CHar-2Ј), 130.33, 130.50 (2 ϫ Colef-3, 2 ϫ
X-ray Crystallography Study
Crystal Data for 22: C21H16, monoclinic, space group P21/n, a ϭ
˚
5.8013(12), b ϭ 25.336(5), c ϭ 10.741(2) A, β ϭ 91.40(3), V ϭ
1578.3(6) A , Z ϭ 4, µ ϭ 0.064 mmϪ1, Dx ϭ 1.129 Mg/m3,
3
˚
F(000) ϭ 568. Data were collected at 173(2) K with a Nonius
Kappa CCD diffractometer using Mo-Kα radiation (λ ϭ 0.71073
A, range for data collection θ ϭ 3.07 to 26.36°, index ranges 0 Յ
˚
˜
Colef-4, Colef-7), 131.86 (2 ϫ CHar-3, CHar-3Ј). Ϫ IR (KBr): ν
h Յ 7, 0 Յ k Յ 31, Ϫ13 Յ l Յ 13), 3190 reflections collected, 3190
independent reflections (Rint ϭ 0.0000), 1695 reflections [I Ͼ 2σ(I)].
Absorption correction method was applied.[33] The structure was
solved by direct methods and refined using full-matrix, least-
squares procedures on F2 (SHELXL93),[34] data/restraints/para-
meters ϭ 3188/0/191, goodness-of-fit on F2 ϭ 1.014, final R indices
R1 ϭ 0.0581 [I Ͼ 2σ(I)], wR2 ϭ 0.1652 (all data) for 191 refined
[cmϪ1] ϭ 3441, 2924, 2850, 1628, 1488, 1442, 1385, 1122, 754, 688.
Ϫ UV/Vis (CH2Cl2): λmax (ε) [nm] ϭ 250.0 (24310), 279.5 (22967),
315.0 (22395), 330.5 (24901), 382.5 (20473). Ϫ MS (FAB): m/z ϭ
448 [M]ϩ. Ϫ C35H28 (448.61): calcd. C 93.71, H 6.29; found C
88.82, H 6.48; m.p. 158 °C.
1,2-Di(1-pentynyl)cyclopent-1-ene (29): Compound 29 was synthe-
sized according to general procedure I, with 1-pentyne (0.36 g) and
1,2-dibromocyclopentene (0.30 g). Product 29 was isolated by flash
parameters, largest diff. peak and hole: 0.1644 and Ϫ0.145 e·AϪ3
.
Crystal Data for 27: C33H32Cl2D2Si, orthorhombic, space group
˚
column chromatography, with hexane/dichloromethane (10:1) as Pmn21 (no. 31), a ϭ 7.107(1), b ϭ 20.988(2), c ϭ 9.917(1) A, V ϭ
Eur. J. Org. Chem. 2001, 3879Ϫ3890
3889

C. Kosinski, A. Hirsch, F. W. Heinemann, F. Hampel
FULL PAPER
[10b]
3
1479.2(3) A , Z ϭ 2, µ ϭ 0.279 mmϪ1, Dx ϭ 1.194 Mg/m3, yellow
˚
Int. Ed. Engl. 1994, 33, 1360Ϫ1363. Ϫ
L. Jones, II, J. S.
Schumm, J. M. Tour, J. Org. Chem. 1997, 62, 1388.
plate, crystal size 0.70 ϫ 0.55 ϫ 0.15 mm, F(000) ϭ 560. Data were
collected at 200 K with a Siemens P4 diffractometer using Mo-Kα
[11] [11a]
R. S. Slysh, Ph.D. Thesis, The Pennsylvania State Univer-
[11b]
sity, College Park, PA, 1960. Ϫ
J. M. Georgiana, M.Sc.
˚
radiation (λ ϭ 0.71073 A, graphite monochromator, ω-scans with
Thesis, The Pennsylvania University, College Park, PA, 1960;
N. L. Desai, Ph.D. Thesis, The Pennsylvania University, Col-
lege Park, PA, 1960.
F. Wudl, P. Bittler, J. Am. Chem. Soc. 1986, 108, 4685.
W. E. Lindsell, P. N. Preston, P. J. Tomb, J. Organomet. Chem.
1992, 439, 201.
K. N. Bharucha, R. M. Marsh, R. E. Minto, R. G. Bergman,
J. Am. Chem. Soc. 1992, 114, 3120.
K. Sonogashira, Y. Tohda, N. Hagihara, Tetrahedron Lett.
1975, 16, 4467.
J. Burdon, Chem. Commun. 1967, 1259; J. Burdon, J. Chem.
Soc., Perkin Trans.1 1972, 639; T. Jeffery, Tetrahedron Lett.
1992, 33, 1989.
K. P. C. Vollhardt, L. S. Winn, Tetrahedron Lett. 1985, 26, 709;
X.-P. Cao, T.-L. Chan, H. F. Chow, Tetrahedron Lett. 1996,
37, 1049.
4.0 °minϪ1
,
3.8 Յ 2θ Յ 56.0°, index ranges Ϫ9 Յ h Յ 9,
Ϫ27 Յ k Յ 27, Ϫ13 Յ l Յ 13); 4072 reflections collected, 3854
unique reflections (Rint ϭ 0.0136), 2731 observed reflections
[Fo Ն 4.0σ(F)]. A ψ-scan absorption correction was applied (Tmin ϭ
0.687, Tmax ϭ 0.715). The structure was solved by direct methods
and refined using full-matrix, least-squares procedures on F2
[12]
[13]
[14]
[15]
[16]
(SHELXTL NT 5.10);[35] final R values R1 ϭ 0.0496 (Fo
Ն
4.0σ(F)], wR2 ϭ 0.0905 (all data) for 268 refined parameters, abso-
lute structure parameter x ϭ Ϫ0.07(9),[36] largest diff. peak and
hole: 0.206 and Ϫ0.276 e·AϪ3. All hydrogen atom positions were
derived from a difference Fourier synthesis and refined with a fixed
common isotropic displacement parameter.
[17]
[18]
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