Double elimination protocol for convenient synthesis of dihalodiphenylacetylenes: Versatile building blocks for tailor-made phenylene-ethynylenes

Article abstract of DOI:10.1002/adsc.200404014

Dihalodiphenylacetylenes are conveniently synthesized by a double elimination reaction of β-substituted sulfones which are readily obtained from halogen-substituted benzyl sulfone and benzaldehyde derivatives. Halogens can be incorporated at any desired positions in the diphenylacetylene skeleton simply by choosing the substitution position of the halogen on the aromatic rings of the starting compounds. The diphenylacetylenes with different halogen substituents thus obtained undergo sequential carbon-carbon bond formations due to the different reactivities of the halogens. Thus, various moieties can be incorporated on the diphenylacetylene skeleton at whichever positions so that a variety of tailor-made phenylene-ethynylenes with regulated structure and composition could be designed.

Full text of DOI:10.1002/adsc.200404014

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Double Elimination Protocol for Convenient Synthesis of
Dihalodiphenylacetylenes: Versatile Building Blocks for
Tailor-Made Phenylene-Ethynylenes
Akihiro Orita, Kazuhiko Miyamoto, Mikio Nakashima, Fangguo Ye, Junzo Otera*
Department of Applied Chemistry, Okayama University of Science, Ridai-cho, Okayama 700-0005, Japan
Fax: (þ81)-86-256-4292, e-mail: otera@high.ous.ac.jp
Received: January 16, 2004; Accepted: March 22, 2004
Dedicated to Dr. Joe P. Richmond on the occasion of his 60th birthday.
Supporting Information for this article is available on the WWW under http://asc.wiley-vch.de or from the author.
Abstract: Dihalodiphenylacetylenes are conveniently carbon bond formations due to the different reactivi-
synthesized by a double elimination reaction of b-sub- ties of the halogens. Thus, various moieties can be in-
stituted sulfones which are readily obtained from hal- corporated on the diphenylacetylene skeleton at
ogen-substituted benzyl sulfone and benzaldehyde whichever positions so that a variety of tailor-made
derivatives. Halogens can be incorporated at any de- phenylene-ethynylenes with regulated structure and
sired positions in the diphenylacetylene skeleton sim- composition could be designed.
ply by choosing the substitution position of the halo-
gen on the aromatic rings of the starting compounds.
The diphenylacetylenes with different halogen sub- Keywords: acetylene; aldehydes; double elimination;
stituents thus obtained undergo sequential carbon- halogen; sulfone;
Introduction
Dihalodiphenylacetylenes 1 would be more versatile
building blocks for phenylene-ethynylenes (Figure 1).
The phenylene-ethynylene array is an important com- In particular, those with different halogen substituents
ponent for organic materials such as liquid crystals,[1] on the respective phenyl rings (1, X=Y) are expected
photo-luminescent compounds[2] and carbon-rich mate- to serve for designing tailor-made phenylene-ethyny-
rials.[3] Sonogashira coupling[4] which is commonly em- lenes with regulated structure and composition because
ployed for arylacetylenes can also be invoked for the different, and hence selective, carbon-carbon bond for-
synthesis of phenylene-ethynylenes. However, the sim- mations are feasible on the both sides of the molecules
ple protocol cannot be applied to the fabrication of on account of different reactivities of the halogens.
this framework, for which a variety of kits must be as-
We have been interested in aromatic acetylenes as
sembled at will, and accordingly, much more elaboration novel organic materials and have developed a conven-
is required. For example, substrates with two terminal ient methodology, i.e., a double elimination protocol,
acetylenes protected by TMS and TIPS groups are occa- for the synthesis of these compounds (Scheme 1).[7] Al-
sionally used. Selective deprotection of the TMS group though this protocol is composed of a number of reac-
followed by Sonogashira reaction at the newly generat- tions such as aldol reaction, protection of the aldolate
ed reaction site incorporates an arylacetylene unit. and double elimination of the resulting b-substituted
Next, deprotection of the remaining TIPS-acetylene sulfone, all operations could be carried out in one-pot.
and another Sonogashira coupling enable incorporation By taking advantage of this protocol, we have already
of the other unit to assemble the repeating arene-acety-
lene kits.[5] Unsymmetrically substituted dihaloarenes
are also useful building blocks.[6] Bromoiodo- and chlor-
oiodobenzenes can be converted to structurally diverse
phenylene-ethynylenes by making use of the different
reactivities of the halogen functions.
Figure 1. Dihalodiphenylacetylenes 1.
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DOI: 10.1002/adsc.200404014
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Akihiro Orita et al.
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succeeded in the preparation of a highly strained cyclic
acetylene,[7c] enantiopure cyclophanes of the phenyl-
ene-ethynylene motif[7d] and unsymmetrically substitut-
ed di(phenylethynyl)benzenes.[7a, b] We postulated that
this methodology could be applied to a convenient syn-
thesis of 1 (Scheme 2). This is indeed the case. We report
herein the straightforward synthesis of dihalodiphenyla-
cetylenes. On account of the facile availability of both
benzyl sulfones and aldehydes substituted by a halogen
at any position of the benzene ring, dihalodiphenylace-
tylenes with all possible substitution patterns are acces-
sible. In addition, the utilization of these compounds for
structurally regulated higher homologues is demon-
strated.
Scheme 3. Preparation of 1g through double elimination of 4
derived from the reaction of 2a with 3g.
parable, but LDA produced an inseparable mixture of 1,
5 and 6.
Next, dihalodiphenylacetylenes with all possible halo-
Results and Discussion
The synthesis of the dihalodiphenylacetylenes by the gen substitution modes were synthesized by use of the
double elimination protocol is straightforward. A proce- corresponding halobenzyl sulfone and halobenzalde-
dure for bromoiododiphenylacetylene 1g is described as
an example (Scheme 3). To a THF solution of bromo
sulfone 2a were added consecutively BuLi, iodobenzal-
deyde 3g, diethyl chlorophosphate and LiHMDS (lithi-
um hexamethyldisilazide) in this order. The desired bro-
moiododiphenylacetylene 1g was obtained in 78% yield.
Although this process is composed of a number of trans-
formations, it was proved by monitoring the reactions
that all steps have proceeded smoothly.[8] After addition
of ClP(O)(OEt)2, the formation of phosphate 4 was
clearly shown on TLC. Addition of LiHMDS gave rise Figure 2. Halobenzyl sulfone and halobenzaldehyde partners.
to the formation of the desired acetylene 1g as the sole
product. A single spot due to 1g was detected on TLC
of the crude product.[8] Although rapid lithium-halogen
exchange often occurs with aryl bromides and iodides,[9]
GC analysis of the crude product indicated no dehaloge-
nation products such as 1-(2-bromophenyl)-2-phenyla-
cetylene (5)[10] and diphenylacetylene (6).[8] When t-
BuOK was used instead of LiHMDS, the yield was com-
Scheme 4. Syntheses of dihalodiphenylacetylenes 1 by use of
2- and 3-bromobenzyl sulfones 2a, b.
Scheme 1. Double elimination of b-substituted sulfones de-
rived from the reaction of a sulfone with an aldehyde.
Scheme 2. Retrosynthesis for unsymmetrically dihalogen-
substituted diphenylacetylenes 1.
Scheme 5. Dimerization of 4-bromobenzyl sulfone 1.
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Convenient Synthesis of Dihalodiphenylacetylenes
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Scheme 6. Syntheses of dihalo diphenylacetylenes 1 by use of
4-bromobenzyl sulfone 3c.
Scheme 8. Sonogashira coupling between diiodobenzene and
4-bromophenylethyne.
necessary for isolation of the pure compound. Appa-
rently, it is difficult to differentiate the same halogen
functions in the Sonogashira reaction. The other route
to arrive at the same target is the combination of 4-bro-
moiodobenzene and 4-iodophenylacetylene. However,
unfavorable self-coupling of the 4-iodophenylacetylene
competes with the desired intermolecular reaction un-
der normal conditions.
With the above compounds in hand, we turned our at-
tention to demonstrate their synthetic potentialas build-
ing blocks for a wide spectrum of higher homologues of
phenylene-ethynylenes. First, homologation by Sonoga-
shira reaction of bromoiododiphenylacetylenes, 1x and
Scheme 7. Syntheses of bromo iodo diphenylacetylenes 1 by
use of iodobenzyl sulfones 2.
hyde partners (Figure 2) under similar conditions. Com- 1bb, was carried out (Scheme 9). As expected, treat-
bination of 2- and 3-bromobenzyl sulfones 2a, b and hal- ment of the substrates with one equivalent of arylacety-
obenzaldehydes 3 furnished the corresponding products lenes resulted in exclusive reaction on the iodide leaving
1a q in good yields irrespective of the position of the the bromide intact to afford the desired arylene-ethyny-
halogens in 3 (Scheme 4). When 4-bromobenzyl sulfone lenes 9a and 9b, respectively. It should be noted that
2c was employed, however, dibromostilbene 7 formed in when a symmetrical dibromodiphenylacetylene 1u was
88% yield (Scheme 5). Fortunately, this reaction was subjected to a similar reaction, the desired monobromo
suppressed by use of LiHMDS instead of BuLi as a compound was obtained only in 47% yield (Scheme 10).
base to generate the a-sulfonylbenzyl anion, and the de- A considerable amount of the di-coupling product was
sired dihalodiphenylacetylenes 1f, n, r u were obtained formed. It is difficult to stop the reaction after the
in good yields (Scheme 6). This modification also al- mono-coupling stage. The corresponding diiodide sub-
lowed us to use iodobenzyl sulfones which are liable to strate brought about a worse outcome: no monoiodides
dehalogenation with BuLi, and the desired coupling were detected at all. As soon as the mono-coupling
products were obtained without loss of the halogen products were formed, they underwent further coupling
(Scheme 7). Note that, when BuLi was employed in immediately. Apparently, the bromo iodo derivative is
place of LiHMDS for the generation a-lithiobenzyl sul- crucial for the selective Sonogashira coupling.
fone, deiodination occurred to produce an inseparable
mixture of 1 and monobromodiphenylacetylene.
Next, analogously prepared monobromides, 9c and
9d, were used for exemplifying the effectiveness to con-
The utility of the double elimination route for the di- trol the structure and composition of the higher phenyl-
halodiphenylacetylenes is apparent from a comparison ene-ethynylene homologues (Scheme 11). Subjection of
with the Sonogashira protocol (Scheme 8). When 1,4- these monobromides to additional Sonogashira reaction
diiodobenzene was subjected to Sonogashira coupling led to 10a and 10b, respectively. The positions of the
with 4-bromophenylacetylene in a 1:1 ratio, the desired ethynyl groups on the aromatic rings can be controlled
coupling product 1bb was contaminated by double cou- by choosing appropriate dihalodiphenylacetylenes. Sub-
pling product 8 together with unreacted diiodobenzene. stituents like the hexyl group can also be incorporated at
Separation of 1 from these contaminants was difficult on whichever positions depending on the substituents of
account of their similar polarity and solubility in organic the starting sulfone and aldehyde. Suzuki Miyaura cou-
solvents, and repeated column chromatography was pling[11] was employable for the second reaction as well,
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Akihiro Orita et al.
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Scheme 9. Syntheses of unsymmetrically substituted acetylenes by use of 1 through Sonogashira coupling.
and a biphenylacetylene derivative 10c was obtained.
The Mizoroki Heck reaction[12] also worked well
(Scheme 12). The reaction of the bromo iodo substrate
1x with methyl acrylate proceeded exclusively on the io-
dide to afford 9e. Subjection of this compound to the So-
nogashira reaction provided an ene-yne 10d, while con-
junction with Suzuki Miyaura coupling furnished the
corresponding biphenyl derivative 10e.
The combination ofbromo and chloro functions is also
useful for selective carbon-carbon bond formations.
Subjection of the bromo-chloro substrate 1 l to a Sono-
gashira reaction led to monochloride 9f, which then un-
derwent Negishi coupling[13] to afford the biphenyl de-
rivative 10c (Scheme 13).
Conclusion
The double elimination reaction of b-substituted sul-
fones has proved to be useful for the synthesis of dihalo-
diphenylacetylenes. In particular, otherwise difficult-to-
prepare diphenylacetylenes with different halogen sub-
stituents are accessible in a straightforward manner.
These compounds are versatile building blocks for high-
er homologues of phenylene-ethynylenes because vari-
ous carbon-carbon bond formations like Sonogashira,
Mizoroki Heck, Suzuki Miyaura, and Negishi cou-
plings can be conducted sequentially on the different
halogen functions. The iodo-bromo and bromo-chloro
substrates undergo exclusive consumption of the iodo
and bromo groups, respectively, in the initial reaction.
The remaining halogen functions undergo the other car-
bon-carbon bond formations. Needless to say, a higher
selectivity would be feasible with chloro-iodo sub-
strates. According to this strategy, various moieties can
be incorporated at any desired position because all sub-
stitution patterns of halogens are accessible for dihalo-
diphenylacetylenes. Notably, the substitution modes
are readily controlled by suitable choice of substituted
benzyl sulfones and benzaldehydes. As a consequence,
À
Scheme 10. Attempts for selective C C bond formation of di-
bromide 1u and diiodide 1aa.
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Convenient Synthesis of Dihalodiphenylacetylenes
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À
Scheme 11. Syntheses of unsymmetrically substituted acetylenes by sequential transition metal-catalyzed C C bond forma-
tions.
Scheme 12. Syntheses of unsymmetrically substituted acetylenes by sequential Mizoroki Heck/Sonogashira or Suzuki
Miyaura couplings.
Scheme 13. Synthesis of unsymmetrically substituted acetylene by sequential Sonogashira/Negishi couplings.
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was stirred for 0.5 h. Diethyl chlorophosphate (0.14 mL,
1.0 mmol) was added at À788C, and the mixture was stirred
at room temperature for 1 h. A THF solution of LiHMDS
(1.0 M, 4.0 mL, 4.0 mmol) was added at À788C, and the mix-
ture was stirred at room temperature for 2 h. After usual
work-up with ethyl acetate and aqueous NH4Cla, followed by
drying over MgSO4 and evaporation, the residue was subjected
to a thin pad of silica gel to furnish 1r in a pure form; yield:
245 mg (84%).
1-(2-Bromophenyl)-2-(2-chlorophenyl)ethyne (1a): mp
82 848C; 1H NMR (300 MHz, CDCl3): d¼7.16 7.34 (m,
4H), 7.41 7.47 (m, 1H), 7.57 7.67 (m, 3H); 13C NMR
(75 MHz, CDCl3): d¼91.2, 93.5, 123.5, 125.7, 126.2, 127.1,
127.7, 130.0, 130.2, 130.4, 133.1, 134.1, 134.2, 136.6; elemental
analysis: calcd. for C14H8BrCl (%): C 57.67, H 2.77; found: C
57.36, H 2.38.
1-(2-Bromophenyl)-2-(3-chlorophenyl)ethyne (1b): mp
34 358C; 1H NMR (300 MHz, CDCl3): d¼7.16 7.23 (m,
1H), 7.26 7.37 (m, 3H), 7.43 7.49 (m, 1H), 7.54 7.65 (m,
3H); 13C NMR (75 MHz, CDCl3): d¼89.8, 93.0, 125.2, 125.5,
126.4, 127.7, 129.5, 130.2, 130.3, 130.4, 132.1, 133.1, 133.9,
134.8; elemental analysis: calcd. for C14H8BrCl (%): C 57.67,
H 2.77; found: C 57.68, H 2.48.
a variety of aromatic acetylene compounds with regulat-
ed structure and composition can be tailored conven-
iently. We believe that the present protocol will find a
wide range of utilization in the synthesis of acetylenic
materials.
Experimental Section
General Remarks
All reactions were carried out under an atmosphere of nitrogen
with freshly distilled solvents, unless otherwise noted. Tetrahy-
drofuran (THF) was distilled from sodium/benzophenone.
Other solvents such as toluene and diisopropylamine were dis-
tilled from CaH2. A hexane solution of BuLi was purchased
from Aldrich and titrated before use by the Gilman method.[14]
A THF solution of LiHMDS was purchased and used without
titration. Pd(PPh3)4 was prepared according to the reported
method.[15] Silica gel (Daiso gel IR-60) was used for column
chromatography. NMR spectra were recorded at 258C on
JEOL Lambda 300 and JEOL Lambda 500 instruments and
calibrated with tetramethylsilane (TMS) as an internal refer-
ence. Elemental analyses were performed with a Perkin Elmer
PE 2400.
1-(2-Bromophenyl)-2-(4-chlorophenyl)ethyne (1c): mp 71
738C; 1H NMR (300 MHz, CDCl3): d¼7.19 (t, J¼7.7 Hz, 1H),
7.26 7.37 (m, 3H), 7.49 7.57 (m, 3H), 7.62 (d, J¼7.7 Hz, 1H);
13C NMR (75 MHz, CDCl3): d¼89.5, 93.3, 122.0, 125.7, 126.2,
127.7, 129.3, 130.2, 133.1, 133.5, 133.8, 135.3; elemental analy-
sis: calcd. for C14H8BrCl (%): C 57.67, H 2.77; found: C 57.56,
H 2.37.
Starting compounds 3a f are commercially available, while
sulfones 2a f and iodobenzaldehyde 3g i were prepared from
the corresponding benzyl bromides and benzyl alcohols, re-
spectively. Experimental details are described in the Support-
ing Information.
1,2-Bis(2-bromophenyl)ethyne
(1d):[7e]
1H NMR
(300 MHz, CDCl3): d¼7.01 (dt, J¼1.5, 7.6 Hz, 2H), 7.12 (dt,
J¼0.9, 7.6 Hz, 2H), 7.45 (dd, J¼1.2, 7.9 Hz, 4H); 13C NMR
(75 MHz, CDCl3): d¼92.8, 125.0, 125.4, 126.9, 129.6, 132.4,
133.5.
Preparation of 1a through Double Elimination of b-
Substituted Sulfone Derived from the Reaction of 2a
with 3a; Typical Procedure
1-(2-Bromophenyl)-2-(3-bromophenyl)ethyne (1e):[16] mp
54 568C; 1H NMR (300 MHz, CDCl3): d¼7.16 7.33 (m,
3H), 7.48 7.56 (m, 3H), 7.62 (d, J¼8.0 Hz, 1H), 7.73 (s, 1H);
13C NMR (75 MHz, CDCl3): d¼89.2, 92.2, 122.2, 124.9, 125.7,
127.1, 129.7, 129.8, 130.2, 131.7, 132.5, 133.3, 134.3.
1-(2-Bromophenyl)-2-(4-bromophenyl)ethyne (1f):[17] mp
To a THF solution (5 mL) of 2-bromobenzyl phenyl sulfone 2a
(372 mg, 1.2 mmol) was added a hexane solution of BuLi (1.60
M, 0.75 mL, 1.2 mmol) at À788C, and the mixture was stirred
for 0.5 h. A THF solution (3 mL) of 2-chlorobenzaldehyde 3a
(141 mg, 1.0 mmol) was added at À788C, and the mixture
was stirred for 0.5 h. Diethyl chlorophosphate (0.14 mL,
1.0 mmol) was added at À788C, and the mixture was stirred
at room temperature for 1 h. A THF solution of LiHMDS
(1.0 M, 4.0 mL, 4.0 mmol) was added at À788C, and the mix-
ture was stirred at room temperature for 2 h. After usual
work-up with ethyl acetate and aqueous NH4Cl, followed by
drying over MgSO4 and evaporation, the residue was subjected
to a thin pad of silica gel to furnish 1a in a pure form; yield:
216 mg (74%).
1
71 738C; H NMR (300 MHz, CDCl3): d¼7.16 (dt, J¼1.7,
7.6 Hz, 1H), 7.26 (dt, J¼0.9, 7.6 Hz, 1H), 7.39 7.55 (m, 5H),
7.60 (d, J¼8.1 Hz, 1H); 13C NMR (75 MHz, CDCl3): d¼89.1,
92.7, 121.8, 122.9, 125.0, 125.6, 127.0, 129.6, 131.6, 132.5,
133.0, 133.2.
1-(2-Bromophenyl)-2-(2-iodophenyl)ethyne (1g):[7e] mp
1
68 708C; H NMR (300 MHz, CDCl3): d¼7.03 (dt, J¼1.5,
7.8 Hz, 1H), 7.20 (dt, J¼1.5, 7.3 Hz, 1H), 7.28 7.38 (m, 2H),
7.56 7.66 (m, 3H), 7.88 (dd, J¼7.8, 1.0 Hz, 1H); 13C NMR
(75 MHz, CDCl3): d¼91.4, 95.5, 100.6, 125.1, 125.5, 127.0,
127.8, 129.5, 129.6, 129.7, 132.5, 133.0, 133.6, 138.8.
1-(2-Bromophenyl)-2-(3-iodophenyl)ethyne (1h): mp 53
558C; 1H NMR (300 MHz, CDCl3): d¼7.10 (t, J¼8.8 Hz,
1H), 7.20 (dt, J¼1.7, 7.5 Hz, 1H), 7.30 (dt, J¼1.2, 7.5 Hz,
1H), 7.50 7.56 (m, 2H), 7.62 (dd, J¼1.2, 8.0 Hz, 1H), 7.69 (d,
J¼7.8 Hz, 1H), 7.92 7.94 (m, 1H); 13C NMR (75 MHz,
CDCl3): d¼89.2, 92.0, 93.7, 124.9, 125.0, 125.7, 127.1, 129.7,
129.9, 130.8, 132.5, 133.3, 137.6, 140.1; elemental analysis:
calcd. for C14H8BrI (%): C 43.90, H 2.11; found: C 43.87, H 2.30.
1-(2-Bromophenyl)-2-(4-iodophenyl)ethyne (1i):[16] mp
Preparation of 1r through Double Elimination of b-
Substituted Sulfone Derived from the Reaction of 2c
with 3a; Typical Procedure
To a THF solution (5 mL) of 4-bromobenzyl phenyl sulfone 2c
(372 mg, 1.2 mmol) was added a THF solution of LiHMDS (1.0
M, 1.2 mL, 1.2 mmol) at À788C, and the mixture was stirred
for 0.5 h. A THF solution (3 mL) of 2-chlorobenzaldehyde 3a
(141 mg, 1.0 mmol) was added at À788C, and the mixture
1
63 658C; H NMR (300 MHz, CDCl3): d¼7.19 (dt, J¼1.8,
772
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7.7 Hz, 1H), 7.25 7.33 (m, 3H), 7.54 (dd, J¼1.8, 7.7 Hz, 1H),
7.61 (dd, J¼1.3, 7.9 Hz, 1H), 7.68 7.73 (m, 2H); 13C NMR
(75 MHz, CDCl3): d¼89.4, 92.9, 94.6, 122.4, 125.0, 125.6,
127.1, 129.6, 132.5, 133.1, 133.2, 137.5.
133.7, 134.8; elemental analysis: calcd. for C14H8BrCl (%): C
57.67, H 2.77; found: C 57.69, H 2.51.
1-(4-Bromophenyl)-2-(4-chlorophenyl)ethyne (1t): mp
1
188 1908C; H NMR (300 MHz, CDCl3): d¼7.30 7.40 (m,
1-(3-Bromophenyl)-2-(2-chlorophenyl)ethyne (1j): mp 57
4H), 7.42 7.51 (m, 4H); 13C NMR (75 MHz, CDCl3): d¼
89.8, 89.9, 122.0, 122.4, 123.3, 129.3, 132.2, 133.4, 133.6, 135.1;
elemental analysis: calcd. for C14H8BrCl (%): C 57.67, H 2.77;
found: C 57.30, H 2.38.
1
598C; H NMR (300 MHz, CDCl3): d¼7.20 7.32 (m, 3H),
7.41 7.58 (m, 4H), 7.71 7.74 (m, 1H); 13C NMR (75 MHz,
CDCl3): d¼88.0, 93.4, 122.8, 123.3, 125.7, 127.1, 129.9, 130.2,
130.4, 130.9, 132.3, 133.9, 135.0, 136.6; elemental analysis:
calcd. for C14H8BrCl (%): C 57.67, H 2.77; found: C 57.77, H
2.50.
1,2-Bis(4-bromophenyl)ethyne (1u):[19] mp 190 1928C;
1H NMR (300 MHz, CDCl3): d¼7.35 7.40 (m, 4H), 7.46
7.52 (m, 4H); 13C NMR (75 MHz, CDCl3): d¼90.0, 122.4,
123.4, 132.3, 133.6.
1-(3-Bromophenyl)-2-(3-chlorophenyl)ethyne (1k):[18] mp
89 918C; 1H NMR (300 MHz, CDCl3): d¼7.18 7.35 (m,
3H), 7.37 7.53 (m, 4H), 7.66 7.70 (m, 1H); 13C NMR
(75 MHz, CDCl3): d¼89.5, 89.7, 122.8, 125.0, 125.3, 129.5,
130.2, 130.3, 130.4, 130.8, 132.1, 132.3, 134.8, 134.9.
1-(4-Bromophenyl)-2-(2-iodophenyl)ethyne (1v): mp 93
948C; 1H NMR (300 MHz, CDCl3): d¼7.03 (dt, J¼1.7,
7.7 Hz, 1H), 7.33 (dt, J¼1.0, 7.7 Hz, 1H), 7.42 7.54 (m, 5H),
7.88 (dd, J¼1.0, 8.0 Hz, 1H); 13C NMR (75 MHz, CDCl3):
d¼91.9, 92.7, 101.1, 121.8, 122.9, 127.9, 129.4, 129.6, 131.7,
132.4, 133.0, 138.8; elemental analysis: calcd. for C14H8BrI
(%): C 43.90, H 2.11; found: C 43.87, H 2.28.
1-(3-Bromophenyl)-2-(4-chlorophenyl)ethyne (1l):[18] mp
101 1038C; 1H NMR (300 MHz, CDCl3): d¼7.08 (t, J¼
7.8 Hz, 1H), 7.30 7.36 (m, 2H), 7.41 7.50 (m, 3H), 7.65
7.70 (m, 1H), 7.87 7.89 (m, 1H); 13C NMR (75 MHz,
CDCl3): d¼89.3, 90.1, 121.8, 122.8, 125.5, 129.4, 130.4, 130.7,
132.2, 133.5, 134.9, 135.3.
1,2-Bis(2-iodophenyl)ethyne (1w):[20] mp 98 1008C;
1H NMR (300 MHz, CDCl3): d¼7.02 (dt, J¼1.6, 7.6 Hz,
2H), 7.33 (dt, J¼0.4, 7.6 Hz, 2H), 7.57 7.67 (m, 2H), 7.84
7.93 (m, 2H); 13C NMR (75 MHz, CDCl3): d¼94.7, 100.5,
127.7, 129.4, 129.6, 132.9, 138.7.
1,2-Bis(3-bromophenyl)ethyne (1m):[18] mp 99 1028C;
1H NMR (300 MHz, CDCl3): d¼7.23 (t, J¼7.8 Hz, 2H),
7.43 7.52 (m, 4H), 7.67 7.69 (m, 2H); 13C NMR (75 MHz,
CDCl3): d¼89.0, 122.2, 124.7, 129.8, 130.2, 131.8, 134.4.
1-(3-Bromophenyl)-2-(4-bromophenyl)ethyne (1n):[18] mp
101 1038C; 1H NMR (300 MHz, CDCl3): d¼7.22 (t, J¼
7.9 Hz, 1H), 7.36 7.51 (m, 6H), 7.66 7.69 (m, 1H); 13C NMR
(75 MHz, CDCl3): d¼88.9, 89.6, 121.7, 122.2, 122.9, 124.9,
129.8, 130.1, 130.2, 131.6, 131.7, 133.1, 134.3.
1-(4-Bromophenyl)-2-(3-iodophenyl)ethyne (1x): mp 107
1
1108C; H NMR (300 MHz, CDCl3): d¼7.09 (t, J¼7.9 Hz,
1H), 7.37 (d, J¼8.4 Hz, 2H), 7.47 7.51 (m, 3H), 7.65 7.70
(m, 1H), 7.87 7.90 (m, 1H); 13C NMR (75 MHz, CDCl3): d¼
88.7, 89.6, 93.7, 121.7, 122.9, 125.0, 129.9, 130.7, 131.7, 133.0,
137.5, 140.1; elemental analysis: calcd. for C14H8BrI (%): C
43.90, H 2.11; found: C 44.09, H 2.18.
1-(3-Bromophenyl)-2-(2-iodophenyl)ethyne (1o): mp 58
598C; 1H NMR (300 MHz, CDCl3): d¼7.04 (dt, J¼1.7,
7.5 Hz, 1H), 7.24 (t, J¼8.0 Hz, 1H), 7.34 (dt, J¼1.0, 7.7 Hz,
1H), 7.47 7.54 (m, 3H), 7.72 7.75 (m, 1H), 7.88 (dd, J¼1.0,
8.0 Hz, 1H); 13C NMR (75 MHz, CDCl3): d¼91.3, 92.8, 101.2,
122.2, 124.9, 127.9, 129.2, 129.7, 129.8, 130.2, 131.8, 132.5,
134.2, 138.8; elemental analysis: calcd. for C14H8BrI (%): C
43.90, H 2.11; found: C 43.85, H 2.29.
1-(3-Bromophenyl)-2-(3-iodophenyl)ethyne (1p): mp 83
848C; 1H NMR (300 MHz, CDCl3): d¼7.09 (t, J¼7.9 Hz,
1H), 7.23 (t, J¼7.9 Hz, 1H), 7.42 7.50 (m, 3H), 7.67 7.70
(m, 2H), 7.87 7.90 (m, 1H); 13C NMR (75 MHz, CDCl3): d¼
88.8, 89.0, 93.7, 122.2, 124.7, 124.8, 129.8, 129.9, 130.1, 130.7,
131.7, 134.3, 137.6, 140.2; elemental analysis: calcd. for C14H8
BrI (%): C 43.90, H 2.11; found: C 43.83, H 2.27.
1-(2-Iodophenyl)-2-(3-iodophenyl)ethyne (1y): mp 74
778C; H NMR (300 MHz, CDCl3): d¼7.00 7.13 (m, 2H),
1
7.30 7.37 (m, 1H), 7.50 7.57 (m, 2H), 7.66 7.73 (m, 1H),
7.85 7.90 (m, 1H), 7.94 (s, 1H); 13C NMR (75 MHz, CDCl3):
d¼91.1, 92.8, 93.7, 101.2, 124.9, 127.8, 129.2, 129.7, 129.8,
130.7, 132.5, 137.5, 138.7, 140.0; elemental analysis: calcd. for
C14H8I2 (%): C 39.10, H 1.88; found: C 39.35, H 1.97.
1,2-Bis(3-iodophenyl)ethyne (1z):[21] mp 105 1068C;
1H NMR (300 MHz, CDCl3): d¼7.09 (t, J¼7.9 Hz, 2H), 7.48
(d, J¼7.9 Hz, 2H), 7.68 (d, J¼7.9 Hz, 2H), 7.88 (s, 2H);
13C NMR (75 MHz, CDCl3): d¼88.9, 93.7, 124.8, 129.9, 130.7,
137.6, 140.2.
1-(3-Iodophenyl)-2-(4-iodophenyl)ethyne (1aa): mp 143
1
1458C; H NMR (300 MHz, CDCl3): d¼7.09 (t, J¼7.9 Hz,
1H), 7.24 (dd, J¼1.4, 7.0 Hz, 2H), 7.48 (d, J¼7.7 Hz, 1H),
7.66 7.73 (m, 3H), 7.88 (s, 1H); 13C NMR (75 MHz, CDCl3):
d¼89.0, 89.7, 93.7, 94.6, 122.2, 124.9, 129.9, 130.6, 133.1,
137.5, 137.6, 140.1; elemental analysis: calcd. for C14H8I2 (%):
C 39.10, H 1.88; found: C 39.39, H 1.92.
1-(3-Bromophenyl)-2-(4-iodophenyl)ethyne (1q): mp 108
1
1108C; H NMR (300 MHz, CDCl3): d¼7.19 7.26 (m, 3H),
7.42 7.50 (m, 2H), 7.65 7.72 (m, 3H); 13C NMR (75 MHz,
CDCl3): d¼89.1, 89.7, 94.6, 122.2, 122.3, 124.9, 129.8, 130.1,
131.6, 133.1, 134.3, 137.6; elemental analysis: calcd. for C14H8
BrI (%): C 43.90, H 2.11; found: C 44.10, H 2.11.
1-(4-Bromophenyl)-2-(4-iodophenyl)ethyne (1bb): mp
210 2138C; 1H NMR (300 MHz, CDCl3): d¼7.24 (d, J¼
8.6 Hz, 2H), 7.38 (d, J¼8.6 Hz, 2H), 7.49 (d, J¼8.4 Hz, 2H),
7.69 (d, J¼8.4 Hz, 2H); 13C NMR (75 MHz, CDCl3): d¼89.6,
89.7, 94.4, 121.9, 122.4, 122.8, 131.7, 132.99, 133.04, 137.6; ele-
mental analysis: calcd. for C14H8BrI (%): C 43.90, H 2.11;
found: C 44.23, H 2.01.
1-(2-Iodophenyl)-2-(4-iodophenyl)ethyne (1cc): mp 75
778C; 1H NMR (300 MHz, CDCl3): d¼7.03 (dt, J¼1.4,
7.8 Hz, 1H), 7.20 (dt, J¼1.7, 7.8 Hz, 1H), 7.28 7.38 (m, 2H),
7.57 7.66 (m, 3H), 7.86 7.90 (m, 1H); 13C NMR (75 MHz,
CDCl3): d¼91.4, 95.5, 100.6, 125.4, 127.0, 127.8, 129.7, 129.8,
1-(4-Bromophenyl)-2-(2-chlorophenyl)ethyne (1r): mp 46
1
488C; H NMR (300 MHz, CDCl3): d¼7.20 7.30 (m, 2H),
7.41 7.44 (m, 3H), 7.46 7.56 (m, 3H); 13C NMR (75 MHz,
CDCl3): d¼87.9, 94.0, 122.4, 123.5, 123.6, 127.1, 130.0, 130.1,
132.3, 133.7, 133.8, 136.5; elemental analysis: calcd. for C14H8
BrCl (%): C 57.67, H 2.77; found: C 57.30, H 2.38.
1-(4-Bromophenyl)-2-(3-chlorophenyl)ethyne (1s): mp
1
104 1068C; H NMR (300 MHz, CDCl3): d¼7.24 7.43 (m,
5H), 7.45 7.55 (m, 3H); 13C NMR (75 MHz, CDCl3): d¼
89.7, 90.1, 122.3, 123.5, 125.2, 129.3, 130.2, 130.3, 132.0, 132.3,
Adv. Synth. Catal. 2004, 346, 767 776
asc.wiley-vch.de
¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
773

Akihiro Orita et al.
FULL PAPERS
132.5, 133.0, 133.6, 138.8; elemental analysis: calcd. for C14H8I2
(%): C 39.10, H 1.88; found: C 39.29, H 1.97.
Mizoroki Heck Reaction of 1-(4-Bromophenyl)-2-(3-
iodophenyl)ethyne (1x) with Methyl Acrylate; Typical
Procedure for Selective C C Bond Formation at an
1,2-Bis(4-iodophenyl)ethyne (1dd):[22] mp 247 2508C;
1H NMR (300 MHz, CDCl3): d¼7.24 (d, J¼8.6 Hz, 4H), 7.69
(d, J¼8.6 Hz, 4H); 13C NMR (75 MHz, CDCl3): d¼90.0,
94.7, 122.8, 133.4, 138.0.
À
Iodide Moiety in 1x
A DMF solution (10 mL) of 1x (383.0 mg, 1.0 mmol), methyl
acrylate (86.1 mg, 1.1 mmol), Pd(OAc)2 (2.2 mg, 0.01 mmol),
Bu4NCl (277.9 mg, 1.0 mmol) and NaHCO3 (210 mg,
2.5 mmol) was heated at 808C for 20 h. After usual work-
up with AcOEt/aqueous NH4Cl, the combined organic layer
was washed with aqueous NaCl, dried over MgSO4 and evapo-
rated. The crude products obtained were subjected to column
chromatography on silica gel (hexanes) to afford methyl
(2E)-3-{3-[2-(4-bromophenyl)ethynyl]phenyl}prop-2-enoate
(9e); yield: 269.5 mg (79%).
Sonogashira Coupling of 1-(4-Bromophenyl)-2-(3-
iodophenyl)ethyne (1x) with Phenylethyne; Typical
À
Procedure for Selective C C Bond Formation at an
Iodide Moiety in 1x
A toluene solution (3 mL) of 1x (191.5 mg, 0.50 mmol), phe-
nylethyne (51.1 mg, 0.50 mmol), Pd(PPh3)4 (28.9 mg,
0.025 mmol), CuI (4.8 mg, 0.025 mmol) and diisopropylamine
(1.0 mL) was stirred at room temperature for 12 h. After filtra-
tion, the filtrate was washed with aqueous NH4Cl, and the
aqueous solution extracted with AcOEt. The combined organ-
ic layer was washed with aqueous NaCl, dried over MgSO4 and
evaporated. The crude products obtained were subjected to
column chromatography on silica gel (5% AcOEt/hexanes)
to afford 3-[2-(4-bromophenyl)ethynyl]-1-(2-phenylethynyl)-
benzene (9d); yield: 151.8 mg (85%).
Negishi Coupling of 3-[2-(4-Chlorophenyl)ethynyl]-1-
(2-phenylethynyl)benzene (9f) with PhZnBr
To a THF solution (2 mL) of iodobenzene (122.4 mg,
0.6 mmol) was added a hexane solution (0.5 mL) of BuLi (1.3
M, 0.65 mmol) at À788C. After 10 min, a THF solution
(2.0 mL) of ZnBr2 (135.1 mg, 0.6 mmol) was added, and the
mixture was stirred at room temperature for 10 min. This mix-
ture was added to a THF solution (3 mL ) of 9f (156.4 mg,
0.5 mmol) and PdCl2(dppf) (20.4 mg, 0.025 mmol), and the
mixture was heated at reflux for 12 h. After usual work-
up with AcOEt/aqueous NH4Cl, the combined organic layer
was washed with aqueous NaCl, dried over MgSO4 and evapo-
rated. The crude products obtained were subjected to column
chromatography on silica gel (hexanes) to afford 1-(2-phenyl-
ethynyl)-3-[2-(4-phenylphenyl)ethynyl]benzene (10c); yield:
134.7 mg (76%).
Sonogashira Coupling of 3-[2-(4-
Bromophenyl)ethynyl]-1-(2-phenylethynyl)benzene
À
(9d) with Phenylethyne; Typical Procedure for C C
Bond Formation at a Bromide Moiety
A toluene solution (5 mL) of 9d (178.6 mg, 0.50 mmol),
phenylethyne (51.1 mg, 0.50 mmol), Pd(PPh3)4 (28.9 mg,
0.025 mmol), CuI (4.8 mg, 0.025 mmol) and diisopropylamine
(2.0 mL) was stirred at 708C for 12 h. After filtration, the fil-
trate was washed with aqueous NH4Cl, and the aqueous solu-
tion extracted with AcOEt. The combined organic layer was
washed with aqueous NaCl, dried over MgSO4 and evaporated.
The crude products obtained were subjected to column chro-
matography on silica gel (hexanes) to afford 1-(2-phenylethyn-
yl)-3-{2-[4-(2-phenylethynyl)phenyl]ethynyl}benzene (10b);
yield: 157.1 mg (83%).
Attempt for Unsymmetrically Substituted Acetylenes
by Sonogashira Coupling of Dibromo- and
Diiodoarene; Typical Procedure for Coupling of 1,4-
Diiodobenzene with 1-Bromo-4-ethynylbenzene)
A toluene solution (10 mL) of 1,4-diiodobenzene (165.0 mg,
0.5 mmol), 1-bromo-4-ethynylbenzene (90.5 mg, 0.50 mmol),
Pd(PPh3)4 (28.9 mg, 0.025 mmol), CuI (4.8 mg, 0.025 mmol)
and diisopropylamine (1.0 mL) was stirred at room tempera-
ture for 12 h. After filtration, the filtrate was washed with aque-
ous NH4Cl, and the aqueous solution was extracted with
AcOEt. The combined organic layer was washed with aqueous
NaCl, dried over MgSO4 and evaporated. The crude products
obtained were subjected to column chromatography on silica
gel to afford 1-(4-bromophenyl)-2-(4-iodophenyl)ethyne
(yield: 24.9 mg, 13%), 1,4-bis[2-(4-bromophenyl)ethynyl]ben-
zene (yield: 74.1 mg, 34%) and 1,4-diiodobenzene (yield:
62.7 mg, 38%).
3-[2-(4-Bromophenyl)ethynyl]-1-[2-(4-hexylphenyl)ethy-
nyl]benzene (9a): mp 81 838C; 1H NMR (300 MHz, CDCl3):
d¼0.88 (t, J¼6.6 Hz, 3H), 1.30 (mc, 6H), 1.61 (mc, 2H), 2.62
(t, J¼8.0 Hz, 2H), 7.17 (d, J¼8.0 Hz, 2H), 7.30 7.51 (m,
9H), 7.69 (s, 1H); 13C NMR (75 MHz, CDCl3): d¼14.1, 22.6,
28.9, 31.2, 31.7, 35.9, 87.8, 88.8, 89.7, 90.4, 120.0, 122.0, 122.7,
123.2, 123.9, 128.4, 128.5, 131.0, 131.5, 131.6, 131.7, 133.0,
Suzuki Miyaura Coupling of 3-[2-(4-
Bromophenyl)ethynyl]-1-(2-phenylethynyl)benzene
À
(9d) with Phenylboronic Acid; Typical Procedure C C
Bond Formation at a Bromide Moiety
A benzene solution (10 mL) of 9d (357.2 mg, 1.0 mmol), phe-
nylboronic acid (182.9 mg, 1.5 mmol), Pd(PPh3)4 (23.1 mg,
0.02 mmol), Ba(OH)2 (octahydrate, 473.2 mg, 1.5 mmol) and
water (3.0 mL) was heated at reflux for 16 h. After usual
work-up with AcOEt/water, the combined organic layer
was washed with aqueous NaCl, dried over MgSO4 and evapo-
rated. The crude products obtained were subjected to column
chromatography on silica gel (5% AcOEt/hexanes) to afford
1-(2-phenylethynyl)-3-[2-(4-phenylphenyl)ethynyl]benzene
(10c); yield: 280.0 mg (79%).
774
¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
Adv. Synth. Catal. 2004, 346, 767 776

Convenient Synthesis of Dihalodiphenylacetylenes
FULL PAPERS
134.5, 143.7; elemental analysis: calcd. for C28H25Br (%): C
76.19, H 5.71; found: C 76.47, H 5.62.
1-(2-Phenylethynyl)-3-[2-(4-phenylphenyl)ethynyl]ben-
zene (10c): mp 156 1588C; 1H NMR (300 MHz, CDCl3): d¼
7.33 7.40 (m, 5H), 7.44 7.56 (m, 6H), 7.61 7.64 (m, 6H),
7.74 (s, 1H); 13C NMR (75 MHz, CDCl3): d¼88.5, 89.2, 89.9,
90.0, 121.9, 123.0, 123.6, 127.0, 127.1, 127.7, 128.3, 128.4,
128.5, 128.9, 131.3, 131.6, 132.1, 134.6, 140.3, 141.1; elemental
analysis: calcd. for C28H18 (%): C 94.88, H 5.12; found: C
94.68, H 5.01.
Methyl (2E)-3-(3-{2-[4-(2-Phenylethynyl)phenyl]ethynyl}-
phenyl)prop-2-enoate (10d): mp 188 1918C; 1H NMR
(300 MHz, CDCl3): d¼3.82 (s, 3H), 6.49 (d, J¼16.1 Hz, 1H),
7.34 7.42 (m, 4H), 7.49 7.56 (m, 8H), 7.67 (d, J¼16.1 Hz,
1H), 7.70 (s, 1H); 13C NMR (75 MHz, CDCl3): d¼51.8, 89.0,
89.9, 90.3, 91.4, 118.8, 122.7, 123.0, 123.9, 128.0, 128.5, 129.0,
131.0, 131.5, 131.6, 133.2, 134.7, 143.9, 167.2; elemental analy-
sis: calcd. for C30H20 (%): C 86.16, H 5.01; found: C 86.31, H 4.89.
1-[2-(4-Bromophenyl)ethynyl]-4-[2-(4-hexyloxyphenyl)ethy-
nyl]benzene (9b): mp 232 2348C; 1H NMR (300 MHz,
CDCl3): d¼0.91 (t, J¼7.3 Hz, 3H), 1.34 1.46 (m, 6H), 1.79
(mc, 2H), 3.97 (t, J¼6.4 Hz, 2H), 6.82 6.89 (m, 2H), 7.37
7.51 (m, 10H); 13C NMR (75 MHz, CDCl3): d¼14.0, 22.6,
25.7, 29.1, 31.5, 68.1, 87.7, 89.9, 90.3, 91.7, 113.6, 114.6, 122.0,
122.2, 122.6, 131.4, 131.6, 133.0, 133.1, 134.0, 159.4, 159.8; ele-
mental analysis: calcd. for C28H25BrO (%): C 73.52, H 5.51;
found: C 73.90, H 5.67.
3-[2-(3-Bromophenyl)ethynyl]-1-[2-(4-hexylphenyl)ethy-
nyl]benzene (9c): mp 86 888C; 1H NMR (300 MHz, CDCl3):
d¼0.89 (t, J¼6.6 Hz, 3H), 1.30 (mc, 6H), 1.61 (mc, 2H), 2.62
(t, J¼7.9 Hz, 2H), 7.17 (d, J¼8.2 Hz, 2H), 7.23 (t, J¼7.9 Hz,
1H), 7.34 (t, J¼7.7 Hz, 1H), 7.43 7.51 (m, 6H), 7.68 7.70
(m, 2H); 13C NMR (75 MHz, CDCl3): d¼14.1, 22.6, 28.9,
31.2, 31.7, 35.9, 87.7, 88.3, 89.9, 90.4, 120.0, 122.2, 123.0, 123.9,
125.0, 128.4, 128.5, 129.8, 130.2, 131.1, 131.4, 131.5, 131.5,
131.7, 134.3, 134.6; elemental analysis: calcd. for C28H25Br
(%): C 76.19, H 5.71; found: C 75.92, H 5.66.
Methyl
(2E)-3-{3-[2-(4-Phenylphenyl)ethynyl]phenyl}-
prop-2-enoate (10e): mp 174 1758C; 1H NMR (300 MHz,
CDCl3): d¼3.83 (s, 3H), 6.49 (d, J¼15.9 Hz, 1H), 7.37 7.51
(m, 5H), 7.55 7.66 (m, 8H), 7.72 (s, 1H); 13C NMR (75 MHz,
CDCl3): d¼51.8, 89.2, 90.1, 118.7, 121.7, 124.1, 127.0, 127.1,
127.7, 127.8, 128.9, 129.0, 131.0, 132.1, 133.1, 134.6, 140.2,
141.2, 143.9, 167.2; elemental analysis: calcd. for C24H18O2
(%): C 85.18, H 5.36; found: C 84.89, H 5.30.
3-[2-(4-Bromophenyl)ethynyl]-1-(2-phenylethynyl)ben-
1
zene (9d): mp 135 1388C; H NMR (300 MHz, CDCl3): d¼
7.33 7.40 (m, 6H), 7.47 7.55 (m, 6H), 7.71 (s, 1H); 13C NMR
(75 MHz, CDCl3): d¼88.4, 88.6, 89.6, 90.1, 121.9, 122.7,
122.9, 123.2, 123.7, 128.4, 128.5, 131.2, 131.5, 131.6, 131.7,
132.5, 133.0, 134.5; elemental analysis: calcd. for C22H13Br
(%): C 73.97, H 3.67; found: C 74.25, H 3.72.
Acknowledgements
Methyl
(2E)-3-{3-[2-(4-Bromophenyl)ethynyl]phenyl}-
Financial support from New Energy and Industrial Technology
Development Organization (NEDO) of Japan for Industrial
Technology Research Grant Program (01B68006d) and the Su-
mitomo Foundation to A. O. is gratefully acknowledged.
prop-2-enoate (9e): mp 133 1358C; 1H NMR (300 MHz,
CDCl3): d¼3.82 (s, 3H), 6.45 (d, J¼16.1 Hz, 1H), 7.36 7.42
(m, 3H), 7.48 7.55 (m, 4H), 7.67 (d, J¼16.1 Hz, 1H), 7.68 (s,
1H); 13C NMR (75 MHz, CDCl3): d¼51.8, 89.1, 89.6, 118.8,
121.8, 122.8, 123.7, 128.0, 129.0, 131.0, 131.7, 133.0, 133.1,
143.8, 167.2; elemental analysis: calcd. for C18H13BrO2 (%): C
63.36, H 3.84; found: C 63.48, H 3.63.
References and Notes
3-[2-(4-Chlorophenyl)ethynyl]-1-(2-phenylethynyl)ben-
1
zene (9f): mp 135 1368C; H NMR (300 MHz, CDCl3): d¼
[1] a) S. Hˆger, V. Enkelmann, K. Bonrad, C. Tschierske,
Angew. Chem. Int. Ed. 2000, 39, 2268; b) C.-H. Lee, T.
Yamamoto, Bull. Chem. Soc. Jpn. 2002, 75, 615; c) C. Se-
kine, K. Iwakura, N. Konya, M. Minai, K. Fujisawa, Liq-
uid Crystals 2001, 28, 1375; d) D. J. Pesak, J. S. Moore,
Angew. Chem. Int. Ed. Engl. 1997, 36, 1636.
7.32 7.37 (m, 6H), 7.44 7.55 (m, 6H), 7.71 (s, 1H); 13C NMR
(75 MHz, CDCl3): d¼88.4, 88.8, 89.5, 90.0, 121.5, 122.9,
123.3, 123.7, 128.4, 128.5, 128.6, 128.7, 131.2, 131.5, 131.6,
132.8, 134.5, 134.6; elemental analysis: calcd. for C22H13Cl
(%): C 84.48, H 4.19; found: C 84.20, H 4.24.
1-[2-(4-Hexylphenyl)ethynyl]-3-{2-[3-(2-phenylethynyl)-
phenyl]ethynyl}benzene (10a): mp 74 778C; 1H NMR
(300 MHz, CDCl3): d¼0.88 (t, J¼3.8 Hz, 3H), 1.31 (mc, 6H),
1.61 (mc, 2H), 2.62 (t, J¼4.8 Hz, 2H), 7.17 (d, J¼5.0 Hz, 2H),
7.20 7.24 (m, 1H), 7.30 7.38 (m, 4H), 7.42 7.56 (m, 8H),
7.67 7.73 (m, 2H); 13C NMR (75 MHz, CDCl3): d¼14.1,
22.6, 28.9, 31.2, 31.7, 35.9, 87.7, 88.3, 88.5, 89.0, 89.9, 90.4,
120.0, 122.2, 123.0, 123.3, 123.9, 125.0, 128.4, 128.5, 129.8,
130.2, 131.1, 131.3, 131.4, 131.5, 131.6, 131.7, 132.5, 134.3,
134.56, 134.6; elemental analysis: calcd. for C36H30 (%): C
93.46, H 6.54; found: C 93.61, H 6.48.
1-(2-Phenylethynyl)-3-{2-[4-(2-phenylethynyl)phenyl]ethy-
nyl}benzene (10b): mp 72 758C; 1H NMR (300 MHz, CDCl3):
d¼7.32 7.38 (m, 7H), 7.48 7.56 (m, 10H), 7.72 (s, 1H);
13C NMR (75 MHz, CDCl3): d¼88.5, 89.0, 89.7, 90.1, 90.4,
91.3, 122.8, 122.9, 123.0, 123.3, 123.4, 123.7, 128.3, 128.3,
128.4, 128.5, 128.6, 131.3, 131.4, 131.5, 131.5, 131.6, 131.6,
134.6; elemental analysis: calcd. for C30H18 (%): C 95.21, H
4.79; found: C 94.88, H 4.44.
[2] a) A. Kokil, I. Shiyanovskaya, K. D. Singer, C. Weder, J.
Am. Chem. Soc. 2002, 124, 9978; b) Y. Morisaki, Y. Chu-
¡
jo, Chem. Lett. 2002, 194; c) O. Mongin, L. Porres, L.
Moreaux, J. Mertz, M. Blanchard-Desce, Org. Lett.
2002, 4, 719.
[3] For carbon anion, see: a) R. Boese, A. J. Matzger,
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