Synthesis and photophysical properties of tetra- and pentaalkynylfluorobenzenes by Sonogashira reactions of novel iodofluorobenzenes

Article abstract of DOI:10.1016/j.tet.2012.10.049

1,2-Difluoro-3,4,5,6-tetraiodobenzene, 1,3-difluoro-2,4,5,6- tetraiodobenzene, 1,4-difluoro-2,3,5,6-tetraiodobenzene and 1-fluoro-2,3,4,5,6- pentaiodobenzene were prepared by oxidative iodination of fluorinated benzenes. Sonogashira cross-coupling reactio

Full text of DOI:10.1016/j.tet.2012.10.049

Tetrahedron 69 (2013) 174e183
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis and photophysical properties of tetra- and
pentaalkynylfluorobenzenes by Sonogashira reactions
of novel iodofluorobenzenes
,
b
,
,
b
,
,
b
d
e
Muhammad Sharif a c, Aneela Maalik a c, Sebastian Reimann a , Jamshed Iqbal , Tamas Patonay ,
ꢀ
Anke Spannenberg b, Alexander Villinger a, Peter Langer a
Institut fur Chemie, Universitat Rostock, Albert-Einstein-Str. 3a, 18059 Rostock, Germany
,b,
*
a
€
€
b
€
€
Leibniz-Institut fur Katalyse an der Universitat Rostock e. V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany
c Department of Chemistry, COMSATS Institute of Information Technology, Abbottabad, Pakistan
d Department of Pharmacy, COMSATS Institute of Information Technology, Abbottabad, Pakistan
e
ꢀ
Department of Organic Chemistry, University of Debrecen, H-4032 Debrecen, Egyetem ter 1, Hungary
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 10 August 2012
Received in revised form 10 October 2012
Accepted 16 October 2012
Available online 30 October 2012
1,2-Difluoro-3,4,5,6-tetraiodobenzene, 1,3-difluoro-2,4,5,6-tetraiodobenzene, 1,4-difluoro-2,3,5,6-
tetraiodobenzene and 1-fluoro-2,3,4,5,6-pentaiodobenzene were prepared by oxidative iodin-
ation of fluorinated benzenes. Sonogashira cross-coupling reactions of these fluorinated perio-
dobenzenes afforded fluorescent penta- and tetraalkynylfluorobenzenes in high yields.
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Organofluorine compounds
Alkynes
Sonogashira reaction
Palladium
Cross-coupling
1. Introduction
been synthesized by different synthetic approaches.12 Hex-
aalkynylbenzenes of C2v symmetry have been prepared by Diel-
Polyalkynylated carbon rich molecules are of considerable
importance as liquid crystals,1 non-linear optical materials,2 light-
emitting materials3 and building blocks for two-dimensional
carbon networks.1a,4 Light emitting materials have been applied
in biological and material sciences, such as FET (field effect tran-
sistors), OLED (organic light emitting devices), photovoltaic cells
seAlder reaction of tetraalkynylcyclopentadienones with
alkynes.13 A method for the synthesis of hexaalkynylbenzenes of
D3h symmetry was developed by Rubin.14 Recently, Anthony et al.
reported the synthesis of a D2h symmetric hexaalkynylbenzene
from tetrabromo-benzoquinone.15 Vollhardt et al. reported the
synthesis of hexaalkynylbenzenes and their application to the
synthesis of archimedanes.16
The fluorine atom has a strong electronic influence on aromatic
compounds. Despite the importance of fluorinated arenes in medicinal
chemistry and material sciences,17,18 peralkynylated fluorobenzenes
have, to the best of our knowledge, not been reported so far. Herein, we
report the synthesis of four novel hexahalobenzenes, i.e., 1,2-difluoro-
3,4,5,6-tetraiodo-benzene, 1,3-difluoro-2,4,5,6-tetraiodobenzene, 1,4-
difluoro-2,3,5,6-tetraiodobenzene and 1-fluoro-2,3,4,5,6-pentaiodo-
benzene. Despite their structural simplicity, only fluo-
ropentaiodobenzene has been previously reported and fully charac-
terized. Although all four compounds represent very interesting
synthetic building blocks, their chemistry has, to the best of our
knowledge, not been studied so far. Herein, we report Sonogashira re-
actions of these molecules, which allow for a convenient synthesis of
hitherto unknown fluorescent tetra- and pentaalkynylfluorobenzenes.
and 3D-optical memory devices.5 Extended
often give rise to extraordinary electronic and optical changes of
the molecule.6 In this context, star-shaped
-conjugated mole-
p-systems of alkynes
p
cules with C6 and C3 symmetries have attracted considerable at-
tention.7 D6h-symmetric hexaethynylbenzenes and related
compounds have been used as core structures for dendritic ma-
terials,8 and functional dyes.9 Recently, hexaethynylbenzene de-
rivatives have also been employed as building blocks for
supramolecular architectures10 and potential nonlinear optical
materials for two-photon absorption (TPA) and third-order optical
nonlinearity.3,11 Functionalized hexa(arylethynyl)-benzenes have
* Corresponding author. E-mail address: Peter.langer@uni-rostock.de (P. Langer).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.10.049

M. Sharif et al. / Tetrahedron 69 (2013) 174e183
175
2. Results and discussion
1,2-Difluoro-3,4,5,6-tetraiodobenzene (1), 1,3-difluoro-2,4,5,6-
tetraiodobenzene (3), 1,4-difluoro-2,3,5,6-tetraiodobenzene (5)
and 1-fluoro-2,3,4,5,6-pentaiodobenzene (7) were prepared in very
good yields by potassium persulfate mediated periodination of 1,2-
difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene and
fluorobenzene, respectively (Scheme 1). The reactions were carried
out using the method recently developed by Rahman et al.19 The
synthesis and characterization of 7 has been previously reported.19
The synthesis of 5 was mentioned in a patent,20 however, spec-
troscopic data were not enclosed. The synthesis of 1 and 3 has, to
the best of our knowledge, not yet been reported. We have fully
characterized all four derivatives and were also able to grow single
crystals and to obtain X-ray crystal structure analyses for all mol-
ecules (Figs. 1e4).
Fig. 2. The molecular structure of 3 in the crystal.
F
F
I2 (5.0 equiv.)
I
I
F
I
K2S2O8 (5.0 equiv.)
F
TFA (5.0 equiv.)
DCE, 80 °C, 90 h
I
1 (90%)
I
I2 (7.0 equiv.)
F
I
F
I
K2S2O8 (5.0 equiv.)
F
F
TFA (5.0 equiv.)
DCE, 80 °C, 90 h
I
3 (88%)
F
F
F
I2 (5.0 equiv.)
I
I
I
I
K2S2O8 (5.0 equiv.)
Fig. 3. The molecular structure of 5 in the crystal.
TFA (5.0 equiv.)
DCE, 80 °C, 90 h
F
5 (80%)
F
F
I2 (8.0 equiv.)
I
I
I
I
K2S2O8 (6.0 equiv.)
TFA (5.0 equiv.)
DCE, 80 °C, 90 h
I
7 (76%)
Scheme 1. Synthesis of fluoroiodobenzenes 1, 3, 5 and 7.
Fig. 4. The molecular structure of 7 in the crystal.
The 13C NMR data reveal interesting structural properties. On
the one hand, the iodo substituent has a strong anisotropic effect
and results in a strong upfield shift of the signal of the carbon atom
attached to the iodine atom. On the other hand, fluorine has
a strong negative inductive effect and a strong downfield shift is
generally observed for the signal of carbon atoms neighbouring to
fluorine.
Fig. 1. The molecular structure of 1 in the crystal.

176
M. Sharif et al. / Tetrahedron 69 (2013) 174e183
Table 1
Due to the
p-donating effect of fluorine, an upfield shift is ob-
Optimization of the synthesis of 2a
served for carbon atoms located ortho to a fluorine atom. In case of
1, a significant upfield shift was observed for carbon atoms C3 and
C6 (97.3 ppm), due to the anisotropic effect of the iodo substituent
Catalyst
Base
T
[ꢀC]
CuI
[mol]
t
[h]
Yielda
[%]
1
2
3
4
5
6
Pd(PPh3)4 (5 mol %)
Pd(PPh3)4 (5 mol %)
HN(iPr)2
NEt3
20
80
80
80
80
5
5
5
5
d
20
20
12
12
12
12
Traces
Traces
48
60
30
and the p-donating effect of the fluoro substituent in ortho position.
For comparison, the signals of carbon atoms C4 and C5 located meta
to the fluoro substituent appears at 115.3 ppm. Carbon atoms C1
and C2 resonate at 150.5 ppm. An upfield shift is observed with
regard to products 3 and 5 (vide infra), due to the neighbourhood of
the second fluoro substituent. The signal of carbon C2 of 3 is dra-
matically shifted upfield (70.7), due the neighbourhood of two
fluoro substituents located in ortho position. For comparison, car-
bon atoms C4 and C6 (located ortho to one fluoro substituent)
resonate at 91.6 ppm and carbon C5 appears at 124.2 ppm. Carbon
atoms C2, C3, C4 and C5 of 5 are all located ortho to one fluoro
substituent and the signal appears at 98.0 ppm. Carbon atoms C2/
C6 of 1-fluoro-2,3,4,5,6-pentaiodobenzene resonate at 96.6 ppm,
due to their location ortho to one fluoro substituent. Carbon atoms
C3/5 appear at 117.8 ppm, while C4 is observed at 124.1 ppm. The
discussion shows the strong influence and the additive character of
Pd(PPh3)2Cl2 (5 mol %)
Pd(OAc)2/S-Phos (5 mol %)
Pd(OAc)2/S-Phos (5 mol %)
Pd(OAc)2 (5 mol %) X-Phos
(10 mol %)/
HN(iPr)2
NEt3
Cs2CO3
NEt3
100
1
78
a
Yields of isolated products.
Four CeC bonds are formed in only one step, which refers to a
nearly quantitative yield and less than 1 mol % of catalyst for
each bond formation. The reaction of 1 with various alkynes, using
our optimized procedure, afforded products 2aei in good yields
(Table 2).
The Sonogashira reaction of 3, 5 and 7 with various alkynes
afforded, following our optimized procedure, the tetra- and
pentaalkynylated fluorobenzenes 4aed, 6aee and 8aeg, re-
spectively (Scheme 2, Tables 3e5). The structures of all products
were confirmed by spectroscopic methods. The structure of 6c
was independently confirmed by X-ray crystal structure analysis
the
p-donating effect of the fluoro substituent on the electron
distribution of the benzene ring.
The Sonogashira coupling of 1 with 7 equiv of phenylacetylene
afforded 3,4,5,6-tetraalkynyl-1,2-difluorobenzene (2a) in up to 78%
yield (Scheme 2). During the optimization (Table 1), the use of steri-
cally demanding ligands, such as X-Phos (2-dicyclohexylphosphino-
20,40,60-triisopropylbiphenyl) or HP(tBu)3BF4, proved to be important.
Table 2
Synthesis of 2aei
2
a
Alkyne
t [h]
Yielda [%]
78
Pd(OAc)2
(5 mol%)
R
R
F
12
X-Phos
F
F
(10 mol%)
I
I
F
I
R
b
c
10
8
65
70
+
CuI, NEt3
dioxane
7eq.
R
I
R
2a-i
1
d
e
f
8
12
12
12
62
67
71
54
R
Pd(OAc)2
(5 mol%)
X-Phos
I
F
F
(10 mol%)
F
F
R
+
CuI, NEt3
dioxane
7eq.
g
I
I
R
R
R
R
I
h
8
70
64
R
4a-d
3
Pd(OAc)2
(5 mol%)
X-Phos
i
12
F
a
F
Yields of isolated products.
(10 mol%)
I
I
I
I
+
R
CuI, NEt3
dioxane
6eq.
Table 3
Synthesis of 4aed
R
R
F
R
R
F
6a-e
4
a
Alkyne
T [ꢀC]
t [h]
Yielda [%]
81
Pd(OAc)2
(5 mol%)
X-Phos
5
F
100
12
F
(10 mol%)
I
I
I
I
b
c
80
10
12
68
75
R
+
CuI, NEt3
dioxane
8eq.
R
R
100
I
R
8a-g
7
d
100
12
83
a
Scheme 2. Synthesis of peralkynylated fluorobenzenes 2aei, 4aed, 6aee and 8aeg.
Yields of isolated products.

M. Sharif et al. / Tetrahedron 69 (2013) 174e183
177
Table 4
Synthesis of 6aee
6
a
Alkyne
T [ꢀC]
t [h]
Yielda [%]
85
100
12
b
c
100
100
12
12
86
80
d
80
10
12
78
83
e
100
a
Yields of isolated products.
Table 5
Synthesis of 8aeg
Fig. 6. Absorption and fluorescence of 2h, 4b, 6d and 8g (measurements in
dichloromethane).
8
Alkyne
T [ꢀC]
t [h]
Yielda [%]
55
a
80
12
6d and 4b, which might be again explained by the more extended
p
-system. Within a series of a specific core structure a bath-
ochromic shift is observed for aryl- as compared to alkyl-
substituted derivatives, due to the extended -system. No clear
b
c
d
e
f
80
100
80
12
12
10
12
12
69
74
68
79
63
p
trend was observed for the influence of different types of sub-
stituents attached to the phenyl group. Comparison of the ab-
sorption and emission of 8d and 8g with the known21 non-
fluorinated penta(alkynyl)benzene derivatives revealed a slight
bathochromic shift in case of the fluorinated compounds. This
might be explained by the electronic correspondence between the
electron donating alkynyl groups and the electron-withdrawing
fluoride substituent.
100
100
In conclusion, we have reported the synthesis of a variety of
hitherto unknown fluorescent tetra- and pentaalkynyl-
fluorobenzenes by Sonogashira reactions of novel hexahalobenzenes,
i.e., 1,2-difluoro-3,4,5,6-tetraiodo-benzene (1), 1,3-difluoro-2,4,5,6-
tetraiodo-benzene (3), 1,4-difluoro-2,3,5,6-tetraiodobenzene (5) and
1-fluoro-2,3,4,5,6-pentaiodobenzene (7). We believe that fluo-
roiodobenzenes 1, 3, 5 and 7 represent interesting building blocks
for other synthetic transformations, which will be studied in the
future.
g
80
12
78
a
Yields of isolated products.
(Fig. 5). The phenyl groups and the central benzene moiety are
nearly in plane. Layers are formed in the crystal lattice.
Compounds 2, 4, 6 and 8 show fluorescence in the range of
352e454 nm (Fig. 6). Comparison of the spectra of derivatives 2h,
4b, 6d and 8g, all containing a p-methoxyphenyl group, reveals that
the absorption and fluorescence depend on the type of core
structure (Table 6). Product 8g, containing five alkynyl groups,
shows a bathochromic shift compared to the tetraalkynyl de-
rivatives. Compound 2h shows a bathochromic shift compared to
Table 6
Photophysical properties of compounds 2aei, 4aed and 6aee and 8aeg (mea-
surements in dichloromethane)
fluo
max
Compd
labs [nm]
l
[nm]
Stokes shift [nm]
([105 Mꢁ1 cmꢁ1
)
2a
2b
2c
2d
2f
309
309
320
229
325
325
333
305
310
314
300
313
317
316
317
258
337
336
317
337
346
390
424
409
352
420
420
396
400
425
410
370
409
421
419
428
360
430
454
421
440
444
81
115
99
123
95
95
63
95
115
96
2g
2h
4a
4b
4c
4d
6a
6b
6c
6d
6e
8c
8d
8e
8f
70
96
104
103
111
102
93
108
104
103
108
8g
Fig. 5. The molecular structure of 6c in the crystal.

178
M. Sharif et al. / Tetrahedron 69 (2013) 174e183
~
3. Experimental section
J¼23.3 Hz, C), 115.3 (C), 150.3 (d, J¼243.2 Hz, CF). IR (KBr): ¼2635,
n
2366, 2340, 2188, 2043, 1979 (w), 1537 (m), 1408, 1402 (s), 1316,
1224, 1172, 1046, 876, 702 (m), 678, 656, 557 (s) cmꢁ1. GCeMS (EI,
70 eV): m/z (%)¼617 ([M]þ, 100), 490 (24), 237 (22), 127 (10), 110
(22). HRMS (EI) calcd for C6F2I4 [M]þ: 617.61413 found 617.613808.
Anal. Calcd for C6F2I4: C, 11.67. Found: C, 11.68.
3.1. General
1H NMR spectroscopy: Bruker: AM 250, Bruker ARX 300, Bruker
ARX 500;
d
¼0.00 ppm for tetramethylsilane;
d
¼7.26 ppm for
(CDCl3); Characterization of the signal fragmentations: s¼singlet,
d¼doublet, dd¼double of doublet, t¼triplet, q¼quartet,
m¼multiplet, br¼broadly. All coupling constants are indicated as
(J). 2D NMR techniques (NOESY, COSY, HMQC and HMBC) were used
for the confirmation of structure. 13C NMR Spectroscopy: Bruker:
AM 250, (62.9 MHz); Bruker: ARX 300, (75 MHz), Bruker: ARX 500,
(125 MHz) Ref: 29.84ꢂ0.01 ppm and 206.26ꢂ0.13 ppm
3.2.2. 1,3-Difluoro-2,4,5,6-tetraiodobenzene (3). Starting with 1,3-
difluorobenzene (1.00 g, 0.008 mol), K2S2O8 (11.0 g, 0.044 mol),
TFA (11.8 g, 0.044 mol) and iodine (16.9 g, 0.067 mmol), 3 was
isolated as a yellow crystalline solid (4.7 g, 88%). Mp 176e177 ꢀC. 19F
NMR (282 MHz, CDCl3):
d
¼ꢁ70.0. 13C NMR (62.8 MHz, CDCl3):
d
¼70.7 (t, J¼36.6 Hz, C), 91.6 (dd, J¼31.9, 3.10 Hz, C), 124.2 (C), 161.0
d¼77.00 ppm for CDCl3. The multiplicity of the carbon atoms was
(dd, J¼241.1, 7.03 Hz, CF), 161.1 (dd, J¼241.1, 7.03 Hz, CF). IR (KBr):
~
determined by the DEPT 135 and APT technique (APT¼Attached
Proton Test) and quoted as CH3, CH2, CH and C for primary, sec-
ondary, tertiary and quaternary carbon atoms. Characterization of
the signal fragmentations: quart¼quartet the multiplicity of the
signals was determined by the DEPT recording technology and/or
the APT recording technology. Mass Spectroscopy: AMD MS40,
Varian MAT CH 7, MAT 731 (EI, 70 eV), Intecta AMD 402 (EI, 70 eV
and CI), Finnigan MAT 95 (CI, 200 eV). High Resolution mass
spectroscopy: Finnigan MAT 95 or Varian MAT 311; Bruker FT CIR,
AMD 402 (AMD Intectra). Infrared spectroscopy (IR): Bruker IFS 66
(FT-IR), Nicolet 205 FT-IR; Nicolet Protege 460, Nicolet 360 Smart
Orbit (ATR); KBr, KAP, Nujol and ATR; Peaks are given following
assignments: w¼weak, m¼medium, s¼strong, br¼broad. Ele-
mental Analysis: LECO CHNS-932, Thermoquest Flash EA 1112. UV/
vis and Fluorescence measurement: UV/vis spectra were recorded
at 20 ꢀC with a Lamda 5 (PerkineElmer) spectrometer with a so-
n
¼2921 (w), 2764 (w), 2591 (w), 2412 (w), 2351 (w), 1667 (w), 1604
(w), 1474 (w), 1380 (w), 1355 (w), 1275 (w), 1238 (w), 1188 (w), 1079
(w), 1033 (w), 923 (w), 889 (w), 820 (w), 699 (w), 634 (w), 559 (w)
cmꢁ1. MS (EI, 70 eV): m/z (%)¼617 (100) [M]þ, 490 (2), 237 (22), 127
(10), 110 (22). HRMS (EI) calcd for C6F2I4 [M]þ: 617.61413; found
617.61438. Anal. Calcd for C6F2I4: C, 11.67. Found: C, 12.15.
3.2.3. 1,4-Difluoro-2,3,5,6-tetraiodobenzene (5). Starting with 1,4-
difluorobenzene (1.00 g, 0.008 mol), K2S2O8 (11.0 g, 0.044 mol),
TFA (11.8 g, 0.044 mol) and I2 (12.1 g, 0.048 mmol), 5 was isolated as
a yellow crystalline solid (4.3 g, 80%). Mp 253e255 ꢀC. 19F NMR
(282 MHz, CDCl3):
d
¼ꢁ54.40. 13C NMR (62.8 MHz, DMSO-d6):
d
¼98.0 (dd, J¼38.6, 4.74 Hz, C), 156.9 (dd, J¼239.5, 4.5 Hz, C). IR
~
(KBr):
n
¼2773 (w), 2655 (w), 2515 (w),1380 (w),1311 (w),1268 (w),
1222 (w), 1172 (w), 1099 (w), 1005 (w), 920 (w), 806 (w), 705 (w),
664 (w), 616 (w), 586 (w), 538 (w) cmꢁ1. MS (EI, 70 eV): m/z (%)¼
617 (100) [M]þ, 491 (17), 490 (11), 363 (31), 237 (14), 128 (13), 110
(17), 43 (14). HRMS (EI): calcd for C6F2I4 [M]þ: 617.61413; found
617.614004. Anal. Calcd for C6F2I4: C, 11.67. Found: C, 11.94.
lution concentration of 10ꢁ5e10ꢁ6 mol Lꢁ1
, lmax in nm. Fluores-
cence spectra were recorded with a Hitachi F-4010 fluorescence
spectrophotometer using similar concentration solutions. Distilled
dichloromethane was used as a solvent. Melting points: micro
€
heating table HMK 67/1825 Kuestner (Buchi apparatus). Column
3.2.4. 1-Fluoro-2,3,4,5,6-pentaiodobenzene (7). Starting with fluo-
robenzene (0.008 mol), K2S2O8 (11.0 g, 0.044 mol), TFA (11.8 g,
0.044 mol) and I2 (19.4 g, 0.077 mmol), 7 was isolated as a yellow
crystalline solid (4.1 g, 76%). Mp 259e260 ꢀC. 19F NMR (282 MHz,
chromatography: chromatography was performed over Merck sil-
ica gel 60 (0.063e0.200 mm, 70e230 mesh) as normal and/or over
mesh silica gel 60 (0.040e0.063 mm, 200e400 mesh) as Flash
Chromatography. All solvents were distilled before use. X-ray
crystal structure analysis:22 crystallographic data were collected on
a Bruker X8Apex, Diffractometer with CCD-Kamera (MoKa und
CDCl3):
d
¼ꢁ39.8. 13C NMR (62.8 MHz, CDCl3):
¼96.6 (d, J¼31.7 Hz,
d
C), 117.8 (d, J¼3.92 Hz, C), 124.1 (C), 158.8 (d, J¼241.6 Hz, CF). IR
~
(KBr):
n
¼2924 (m), 2810 (m), 2778 (m), 2533 (m), 2477 (m), 2351
ꢁ
Graphit Monochromator¼0.71073 A). The structures were solved
(m), 1693 (m), 1650 (m), 1587 (m), 1494 (m), 1471 (m), 1327 (s), 1274
(s), 1206 (m), 1150 (m), 1052 (m), 923 (m), 875 (s), 802 (m), 764 (m),
688 (m), 620 (s), 584 (s), 539 (m) cmꢁ1. MS (EI, 70 eV): m/z (%)¼726
(30) [M]þ, 600 (100), 473 (25), 346 (22), 219 (16), 92 (19). HRMS (EI)
calcd for C6FI5 [M]þ: 725.52319; found: 725.519725.
by direct methods using SHELXS-97 and refined against F2 on all
data by full matrix least-squares with SHELXL-97. SCHAKAL 99
program (Schakal 99. Keller, E.; University of Freiburg, Germany,
1999) is used for the molecular representation of crystal structures.
3.2. General procedure for the periodination
3.3. General procedure for Sonogashira coupling reactions
The arene (1.0 mmol), molecular iodine and K2S2O8 were dis-
solved in dichloroethane (DCE) (10 mL). The reaction mixture was
stirred at 0 ꢀC for 5 min and then TFA (4 mL) and H2SO4 (concen-
trated, 0.18 mL, 1 mmol) were slowly added with stirring. The
mixture was stirred at 0 ꢀC for 10 min and at 20 ꢀC for 15 min.
Subsequently, the temperature of the mixture was slowly increased
to the indicated temperature and the mixture was stirred until
completion of the reaction. The mixture was cooled and poured
into ice-cold H2O (40e50 mL). The precipitated solid was filtered
off, washed with H2O (30e40 mL) and subsequently with CH2Cl2
(20e25 mL) to remove unreacted iodine.
A suspension of tetraiodobenzenes (1, 3, 5, 7), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), CuI (5 mol %), Cs2CO3 (5 equiv) in 1,4-dioxane or
DMF was degassed three time in a pressure tube. The alkyne
(1.2 equiv per bromine atom) was added using a syringe. The
mixture was heated at the indicated temperature (60e100 ꢀC) for
12e72 h. The reaction mixture was filtered and the residue was
washed with CH2Cl2. The filtrate was washed with a saturated so-
lution of ammonium chloride (2ꢃ25 mL), water (2ꢃ25 mL) and
dried over anhydrous Na2SO4. The solvent was removed in vacuo.
The product was purified by column chromatography on silica gel.
3.3.1. 1,2-Difluoro-3,4,5,6-tetrakis(phenylethynyl)benzene
(2a). Starting with 1 (150 mg, 0.24 mmol), phenylacetylene
(149 mg, 1.45 mmol), CuI (5 mol %), X-Phos (10 mol %), Pd(OAc)2
(5 mol %), Cs2CO3 (5 equiv) and DMF (5 mL), 2a was isolated as
a yellow solid (97 mg, 78%). Mp 150e152 ꢀC. 1H NMR (300 MHz,
3.2.1. 1,2-Difluoro-3,4,5,6-tetraiodobenzene (1). Starting with 1,2-
difluorobenzene (1.00 g, 0.008 mol), K2S2O8 (11.0 g, 0.044 mol),
TFA (11.8 g, 0.044 mol) and I2 (12.1 g, 0.048 mmol), 1 was isolated as
a yellow crystalline solid (4.8 g, 90%). Mp 153e155 ꢀC. 19F NMR
(282 MHz, CDCl3):
d
¼ꢁ94.3. 13C NMR (62.8 MHz, CDCl3):
d
¼97.3 (d,
CDCl3):
d
¼7.27e7.34 (m, 10H, ArH), 7.52e7.57 (m, 10H, ArH). 13C

M. Sharif et al. / Tetrahedron 69 (2013) 174e183
179
NMR (75.4 MHz, CDCl3):
d
¼80.8 (C^C), 85.9 (C^C), 98.5 (C^C),
2901 (w), 2865 (w), 2710 (w), 2212 (w),1912 (w),1660 (w),1607 (w),
1587 (w),1552 (w),1515 (w),1455 (m),1409 (w),1391 (w),1315 (w),
1267 (w),1200 (w),1182 (w),1107 (m),1079 (w),1064 (w),1015 (w),
943 (m), 830 (s), 784 (w), 735 (w), 697 (w), 656 (w), 620 (w), 559 (s),
528 (w). MS (EI, 70 eV); m/z (%)¼728 (36) [M]þ, 617 (73), 364 (15),
237 (10), 128 (27), 110 (20), 57 (17), 44 (100). HRMS (EI) calcd for
C54H52F2 [M]þ: 738.40316; found 738.409188.
101.4 (C^C), 116.1 (t, J¼6.25 Hz, C), 122.6 (d, J¼58.7 Hz, C), 125.1 (C),
128.2 (CH), 128.5 (CH), 129.1 (d, J¼38.7 Hz, CH), 131.6 (CH), 131.7
(CH), 131.9 (CH), 150.1 (dd, J¼256.2, 16.3 Hz, CF). 19F NMR (282 MHz,
~
CDCl3):
d
¼ꢁ131.12. IR (ATR, cmꢁ1):
¼3078 (w), 3052 (w), 3030 (w),
n
2928 (w), 2872 (w), 2714 (w), 2524 (w), 2435 (w), 2393 (w), 2207
(w),1947 (w), 1872 (w),1798 (w), 1744 (w),1666 (w),1584 (w),1492
(m), 1453 (m), 1441 (m), 1409 (m), 1355 (w), 1327 (w), 1276 (w),
1235 (w),1194 (w), 1174 (w), 1132 (w),1093 (w),1066 (m),1023 (m),
998 (w), 966 (w), 934 (m), 910 (w), 871 (w), 835 (w), 771 (w), 748
(s), 682 (s), 622 (w), 577 (m), 528 (m). MS (EI, 70 eV); m/z (%)¼514
(100) [M]þ, 513 (19), 512 (17), 492 (10), 436 (14), 385 (19), 384 (78),
369 (10), 198 (11). HRMS (EI) calcd for C38H20F2 [M]þ: 514.15276;
found 514.153109.
3.3.5. 1,2-Difluoro-3,4,5,6-tetrakis(4-n-propyl-phenylethynyl)-ben-
zene (2e). Starting with 1 (100 mg, 0.16 mmol), 4-n-propyl-butyl-
phenylacetylene (139 mg, 0.97 mmol), CuI (5 mol %), X-Phos
(10 mol %), Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and DMF (5 mL), 2e
was isolated as a yellow oil (74 mg; 67%). 1H NMR (300 MHz,
CDCl3):
2.54 (t, J¼7.4 Hz, 8H, CH2), 7.09e7.13 (m, 8H, ArH), 7.44e7.47 (m, 8H,
ArH). 13C NMR (75.4 MHz, CDCl3):
d
¼0.89 (t, J¼7.11 Hz, 12H, CH3), 1.53e1.66 (sext, 8H, CH2),
3.3.2. 1,2-Difluoro-3,4,5,6-tetrakis(4-methylphenylethynyl)-benzene
(2b). Starting with 1 (150 mg, 0.24 mmol), 4-methylphenyl-
acetylene (168 mg, 1.45 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and DMF (5 mL), 2b was iso-
lated as a yellow solid (90 mg; 65%). Mp 171e173 ꢀC. 1H NMR
d¼13.8 (2CH3), 24.3 (2CH2), 38.0
(2CH2), 80.5 (C^C), 85.5 (C^C), 98.6 (C^C), 101.6 (C^C), 119.7 (C),
120.2 (C), 125.0 (C), 128.6 (C), 128.7 (CH), 131.5 (CH), 131.8 (CH),
143.9 (C), 144.3 (C), 160.2 (dd, J¼251.0, 13.6 Hz, CF). 19F NMR
~
(282 MHz, CDCl3):
d
¼ꢁ131.76. IR (ATR, cmꢁ1):
¼3400 (w), 3119
n
(300 MHz, CDCl3):
d
¼2.33 (s, 12H, CH3), 7.09e7.14 (m, 8H, ArH),
(w), 3078 (w), 2956 (m), 2927 (m), 2869 (m), 2732 (w), 2668 (w),
2206 (m), 1906 (w), 1787 (w), 1703 (w), 1666 (w), 1604 (w), 1553
(w), 1509 (m), 1454 (s), 1412 (m), 1338 (m), 1258 (m), 1178 (m), 1113
(m), 1079 (m), 1018 (m), 941 (m), 867 (m), 800 (s), 741 (m), 660 (m),
561 (m), 528 (m). MS (EI, 70 eV); m/z (%)¼682 (91) [M]þ, 653 (11),
397 (17), 396 (78), 394 (20), 329 (12), 153 (10), 44 (100). HRMS (EI)
calcd for C50H44F2 [M]þ 682.34056; found 682.339960.
7.42e7.45 (m, 8H, ArH). 13C NMR (75.4 MHz, CDCl3):
d¼21.60, 21.63,
29.6 (CH3), 80.5 (C^C), 85.5 (C^C), 98.5 (C^C), 101.5 (C^C), 115.9
(CH),119.4 (C),119.9 (C),125.0 (C),128.2 (CH),129.5 (CH),131.6 (CH),
139.1 (C), 139.6 (C), 159.8 (d, JCF¼247.6 Hz, CF). 19F NMR (282 MHz,
~
CDCl3):
d
¼ꢁ131.78. IR (ATR, cmꢁ1):
¼3051 (w), 3028 (w), 2960
n
(w), 2917 (w), 2849 (w), 2733 (w), 2204 (w), 1895 (w), 1739 (w),
1603 (m), 1581 (w), 1509 (m), 1450 (m), 1412 (w), 1378 (w), 1316
(w), 1280 (w), 1260 (w), 1212 (w), 1195 (w), 1177 (w), 1101 (m), 1076
(w), 1037 (w), 1019 (m), 941 (m), 869 (w), 810 (s), 728 (w), 659 (w),
646 (w). MS (EI, 70 eV); m/z (%)¼6570 (41) [M]þ. HRMS (EI): calcd
for C42H28F2 [M]þ: 570.21536; found 570.213690.
3.3.6. 1,2-Difluoro-3,4,5,6-tetra(4-n-pentylphenylethynyl)-benzene
(2f). Starting with 1 (150 mg, 0.24 mmol), 4-n-pentylphenylace-
tylene (206 mg, 1.20 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and 1,4-dioxane (5 mL), 2f was
isolated as a brown solid (137 mg; 71%). Mp 72e74 ꢀC. 1H NMR
3.3.3. 1,2-Difluoro-3,4,5,6-tetra(3-methylphenylethynyl)-benzene
(2c). Starting with 1 (150 mg, 0.24 mmol), 3-methylphenyl-
acetylene (139 mg, 1.20 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and 1,4-dioxane (5 mL), 2c was
isolated as an orange solid (98 mg; 70%). Mp 151e153 ꢀC. 1H NMR
(300 MHz, CDCl3):
d
¼0.82 (m, 12H, CH3), 1.23e1.26 (m, 16H, CH2),
1.49e1.59 (m, 8H, CH2), 2.54 (t, J¼7.7 Hz, 8H, CH2CH2CH2CH2CH3),
7.08 (dd, J¼8.4, 5.9 Hz, 8H, ArH), 7.43 (dt, J¼8.5, 1.0 Hz, 8H, ArH). 13C
NMR (75.4 MHz, CDCl3):
d¼14.0 (4CH3), 22.6 (4CH2), 30.9 (4CH2),
31.5 (4CH2), 36.0 (4CH2), 80.6 (C^C), 85.6 (C^C), 98.6 (C^C), 101.1
(C^C), 116.0 (C), 116.3 (C), 119.7 (C), 120.2 (C), 125.0 (C), 125.3 (C),
126.6 (C), 128.6 (2C), 131.8 (d, J¼8.3 Hz, 2CH), 144.4 (C), 150.0 (d,
JCF¼256.8 Hz, CF), 150.5 (d, JCF¼256.8 Hz, CF). 19F NMR (282 MHz,
~
(300 MHz, CDCl3):
(m, 4H, ArH), 7.31 (q, J¼15.1, 7.4 Hz, 4H, ArH), 7.48e7.52 (m, 8H,
ArH). 13C NMR (75.4 MHz, CDCl3):
d
¼2.38 (s, 6H, CH3), 2.41 (s, 6H, CH3), 7.23e7.27
d
¼21.2 (2CH3), 21.3 (2CH3), 80.8
(C^C), 85.8 (C^C), 98.7 (C^C), 101.7 (C^C), 116.1 (t, J¼6.4 Hz, 2C),
122.3 (C), 122.8 (2C), 125.2 (t, J¼2.8 Hz, C), 128.4 (d, J¼2.2 Hz, 4C),
128.9 (4CH), 129.0 (4CH), 130.2 (4CH), 132.5 (d, J¼4.4 Hz, 4C), 138.2
(C), 138.6 (C), 150.0 (d, JCF¼256.2 Hz, CF), 150.5 (d, JCF¼256.2 Hz, CF).
~
CDCl3):
d
¼ꢁ131.89 (CF). IR (ATR, cmꢁ1):
¼3030 (w), 2925 (m),
n
2854 (m), 2206 (w), 1901 (w), 1605 (w), 1511 (m), 1453 (s), 1376 (w),
1284 (w), 1200 (w), 1177 (w), 1115 (w), 1079 (w), 1018 (w), 941 (m),
849 (m), 806 (s), 729 (m), 688 (w), 644 (w), 527 (s), 479 (w), 428 (w)
cmꢁ1. UVevis (CH2Cl2) lmax: 229, 255, 325, 369 nm. Fluorescence
(CH2Cl2, lexcitation¼350 nm): lmax (emission)¼420 nm. MS (EI,
70 eV); m/z (%)¼794 (100) [M]þ, 44 (28). HRMS (EI) calcd for
C58H60F2 [M]þ: 794.46576; found 794.465130. Anal. Calcd for
C58H60F2: C, 87.61. H, 7.61. Found: C, 87.64. H, 7.64.
19F NMR (282 MHz, CDCl3):
d
¼ꢁ131.45 (CF). IR (ATR, cmꢁ1):
¼2916
n
(w), 2202 (w), 1773 (w), 1577 (w), 1487 (w), 1452 (w), 1408 (w),
1293 (w), 1268 (w), 1152 (w), 1093 (w), 997 (w), 960 (w), 902 (w),
854 (w), 777 (w), 683 (w), 586 (w), 569 (w), 501 (w), 435 (w), 383
(w) cmꢁ1. UVevis (CH2Cl2) lmax: 233, 255, 320, 362 nm. Fluores-
cence (CH2Cl2, lexcitation¼350 nm): lmax (emission)¼409, 421 nm.
MS (EI, 70 eV); m/z (%)¼570 (100) [M]þ, 555 (20), 540 (14). HRMS
(EI) calcd for C42H28F2 [M]þ: 570.21536; found 570.216596. Anal.
Calcd for C42H28F2: C, 88.40. H, 4.95. Found: C, 88.45. H, 4.99.
3.3.7. 1,2-Difluoro-3,4,5,6-tetra(n-heptylphenylethynyl)-benzene
(2g). Starting with 1 (150 mg, 0.24 mmol), n-heptylphenylacety-
lene (240 mg, 1.20 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and 1,4-dioxane (5 mL), 2g was
isolated as a yellow solid (120 mg, 54%). Mp 46e48 ꢀC. 1H NMR
3.3.4. 1,2-Difluoro-3,4,5,6-tetrakis(4-tert-butylphenylethynyl)-ben-
zene (2d). Starting with 1 (100 mg, 0.16 mmol), 4-tert-butylpheny-
lacetylene (153 mg, 0.97 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv)and DMF(5 mL), 2dwasisolated
(300 MHz, CDCl3):
d
¼0.88 (t, 12H, CH3), 1.28e1.32 (m, 30H, CH2),
1.56e1.65 (m, 10H, CH2), 2.62 (t, J¼7.6 Hz, 8H, CH2), 7.17 (dd, J¼8.3,
5.6 Hz, 8H, ArH), 7.52 (dt, J¼8.35, 1.95 Hz, 8H, ArH). 13C NMR
as a yellow oil (74 mg; 62%). 1H NMR (300 MHz, CDCl3):
d
¼1.27 (s,
18H, CH3), 1.28 (s, 18H, CH3), 7.19e7.35 (m, 8H, ArH), 7.47e7.50 (m,
8H, ArH). 13C NMR (75.4 MHz, CDCl3):
(75.4 MHz, CDCl3):
d
¼14.1 (4CH3), 22.7 (4CH2), 29.2 (4CH2), 29.3
(4CH2), 31.3 (4CH2), 31.8 (4CH2), 36.1 (4CH2), 80.5 (C^C), 85.6
(C^C), 98.6 (C^C), 101.6 (C^C), 116.0 (2C), 116.6 (2C), 119.9 (2C),
120.2 (2C), 125.1 (2C), 128.6 (8CH), 131.8 (8CH), 144.1 (C), 149.8 (d,
JCF¼257.9 Hz, CF), 150.0 (d, JCF¼257.9 Hz, CF). 19F NMR (282 MHz,
~
d
¼31.2 [(CH3)3C], 34.9
(C(CH3)), 80.5 (C^C), 85.5 (C^C), 98.5 (C^C),101.5 (C^C),119.5 (C),
120.0 (C), 125.04 (C), 125.5 (CH), 131.6 (CH), 131.7 (CH), 152.3 (C),
152.6 (C), 158.1 (d, J¼242.2 Hz, CF). 19F NMR (282 MHz, CDCl3):
~
CDCl3):
d
¼ꢁ131.90 (CF). IR (ATR, cmꢁ1):
¼2954 (w), 2922 (s), 2852
n
d
¼ꢁ131.77, ꢁ131.77. IR (ATR, cmꢁ1):
n
¼3083 (w), 3035 (w), 2956 (m),
(m), 2208 (w), 1605 (w), 1511 (w), 1455 (s), 1376 (w), 1178 (w), 1116

180
M. Sharif et al. / Tetrahedron 69 (2013) 174e183
(w), 1018 (w), 942 (w), 805 (m), 724 (w), 526 (m) cmꢁ1. UVevis
(CH2Cl2) lmax: 229, 255, 325, 368 nm. Fluorescence (CH2Cl2,
lexcitation¼350 nm): lmax (emission)¼420 nm. MS (EI, 70 eV); m/z
(%)¼907 (65) [M]þ, 906 (99), 57 (12), 44 (100), 43 (15). HRMS (EI)
calcd for C66H77F2 [M]þ: 907.59879; found 907.596555.
124e126 ꢀC. 1H NMR (300 MHz, CDCl3):
d
¼3.88e3.94 (m, 12H,
OCH3), 6.90e6.97 (m, 9H, ArH), 7.07 (d, J¼8.5 Hz, 2H, ArH),
7.55e7.60 (m, 5H, ArH). 19F NMR (282 MHz, CDCl3):
d
¼ꢁ102.21. IR
(ATR, cmꢁ1):
n
¼2917 (w), 2542 (w), 2205 (w), 1644 (w), 1602 (w),
~
1567 (w), 1509 (w), 1447 (w), 1368 (w), 1289 (w), 1245 (w), 1169
(w), 1104 (w), 1028 (w), 955 (w), 913 (w), 868 (w), 828 (w), 766 (w),
708 (w), 679 (w), 615 (w), 532 (w). MS (EI, 70 eV); m/z (%)¼634 (17)
[M]þ, 397 (23), 396 (100), 394 (25), 329 (13), 210 (10), 186 (10), 153
(10), 152 (10). HRMS (EI) calcd for C42H28O4F1 [M]þ: 634.19502;
found 634.197057.
3.3.8. 1,2-Difluoro-3,4,5,6-tetrakis(4-methoxylphenylethynyl)-ben-
zene (2h). Starting with 1 (150 mg, 0.24 mmol), 4-methoxyphenyl-
acetylene (191 mg, 1.45 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and DMF (5 mL), 2h was
isolated as a yellow solid (107 mg; 70%). Mp 151e153 ꢀC. 1H NMR
(300 MHz, CDCl3):
6.79e6.83 (m, 8H, ArH), 7.44e7.48 (m, 8H, ArH). 13C NMR
(75.4 MHz, CDCl3):
d
¼3.75 (s, 6H, OCH3), 3.76 (s, 6H, OCH3),
3.3.12. 1,3-Difluoro-2,4,5,6-tetra(4-n-pentylphenylethynyl)-benzene
(4c). Starting with 3 (100 mg, 0.16 mmol), 4-n-pentylphenylace-
tylene (137 mg, 0.80 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and 1,4-dioxane (5 mL), 4c was
isolated as a dark brown oil (97 mg, 75%). 1H NMR (300 MHz,
d
¼55.4 (2OCH3), 80.1 (C^C), 85.1 (C^C), 98.3
(C^C), 101.4 (C^C), 114.2 (CH), 114.6 (CH), 115.2 (C), 122.2 (C), 124.8
(C), 128.8 (CH), 130.9 (CH), 133.3 (CH), 133.5 (CH), 152.2 (d,
J¼258.0 Hz, CF), 160.1 (C), 167.8 (C). 19F NMR (282 MHz, CDCl3):
~
CDCl3):
d
¼0.79e0.84 (m, 12H, 4CH3), 1.23e1.26 (m, 16H, 8CH2),
d
¼ꢁ132.35. IR (ATR, cmꢁ1):
n
¼2957 (w), 2931 (w), 2838 (w), 2536
1.47e1.57 (m, 8H, 2CH2), 2.54 (t, J¼7.6 Hz, 8H, 4CH2), 7.06e7.12 (m,
(w), 2206 (w), 2041 (w), 1907 (w), 1722 (w), 1660 (w), 1602 (m),
1565 (w), 1509 (s), 1455 (m), 1415 (w), 1389 (w), 1286 (m), 1244 (s),
1203 (w), 1177 (m), 1167 (s), 1103 (m), 1072 (w), 1022 (s), 939 (m),
832 (s), 795 (m), 743 (w), 705 (w), 651 (w), 642 (w), 636 (w), 533
(m). MS (EI, 70 eV); m/z (%)¼634 (100) [M]þ. HRMS (EI) calcd for
C42H28O4F2 [M]þ: 634.19502; found 634.195842.
8H, ArH), 7.40e7.45 (m, 8H, ArH). 13C NMR (75.4 MHz, CDCl3):
d¼14.1 (4CH3), 22.6 (4CH2), 30.9 (d, J¼2.0 Hz, 4CH2), 31.5 (4CH2),
36.3 (d, J¼2.0 Hz, 4CH2), 76.2 (d, J¼165.9 Hz, C^C), 76.6 (C^C), 80.0
(C^C), 85.9 (t, J¼4.8 Hz, C^C), 99.0 (t, J¼3.0 Hz, C), 101.4 (t,
J¼4.8 Hz, C), 101.6 (C), 103.1 (t, J¼20.6 Hz, C), 111.2 (C), 111.5 (d,
J¼7.8 Hz, C), 119.4 (C), 119.9 (d, J¼4.2 Hz, C), 128.6 (6CH), 128.6 (CH),
131.7 (3CH), 131.9 (CH), 132.0 (CH), 149.2 (C), 144.6 (d, J¼2.0 Hz, C),
161.5 (d, JCF¼259.1 Hz, CF), 161.8 (d, JCF¼259.1 Hz, CF). 19F NMR
~
3.3.9. 1,2-Difluoro-3,4,5,6-tetrakis(4-n-butyl-ethynyl)benzene (2i). Starting
with 1 (100 mg, 0.16 mmol), 4-n-butyl-acetylene (80 mg, 0.97 mmol), CuI
(5 mol %), X-Phos (10 mol %), Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and
DMF (5 mL), 2i was isolated as a yellow oil (45 mg; 64%). 1H NMR
(282 MHz, CDCl3):
d
¼ꢁ101.12 (CF). IR (ATR, cmꢁ1):
¼3027 (w),
n
2955 (w), 2925 (m), 2854 (m), 2204 (w), 1905 (w), 1606 (w), 1509
(m), 1444 (s), 1377 (w), 1262 (w), 1178 (w), 1092 (m), 1019 (m), 904
(w), 809 (m), 727 (w), 661 (w), 551 (m), 459 (w) cmꢁ1. UVevis
(CH2Cl2) lmax: 228, 262, 314, 355 nm. Fluorescence (CH2Cl2,
lexcitation¼350 nm): lmax (emission)¼410 nm. MS (EI, 70 eV); m/z
(%)¼794 (100) [M]þ, 737 (10), 625 (11), 338 (10), 285 (10), 284 (23),
44 (53), 43 (11), 41 (13) cmꢁ1. HRMS (EI) calcd for C58H60F2 [M]þ:
794.46576; found 794.465446.
(300 MHz, CDCl3):
d
¼0.88 (t, J¼7.20 Hz, 12H, CH3),1.40e1.57 (m, 16H CH2),
2.40e2.46 (sext, 8H, CH2). 13C NMR (75.4 MHz, CDCl3):
d
¼13.6 (2CH3), 19.6
(2CH3), 21.9 (2CH2), 22.6 (2CH2), 29.6 (2CH2), 30.6 (2CH2), 31.5 (2CH2), 38.1
(2CH2), 59.5 (C^C), 72.3 (C^C), 98.5 (C^C), 102.1 (CC), 125.9 (C), 135.5 (C),
137.0 (C), 148.3 (C), 150.9 (dd, JCF¼246.8, 14.3 Hz, CF). 19F NMR (282 MHz,
~
CDCl3):
d
¼ꢁ133.81. IR (ATR, cmꢁ1):
¼3390 (w), 2956 (w), 2930 (w), 2871
n
(w), 2228 (w), 1714 (w), 1683 (w), 1608 (w), 1558 (w), 1509 (w), 1456 (m),
1378 (w), 1341 (w), 1246 (w), 1180 (w), 1119 (w), 1068 (w), 997 (w), 900
(w), 828 (w), 745 (w), 723 (w), 694 (w), 541 (m). MS (EI, 70 eV); m/z (%)¼
434 (36) [M]þ, 397 (33), 396 (94), 394 (36), 331 (11), 329 (21), 277 (15), 210
(15), 198 (11), 186 (16), 44 (100). HRMS (EI) calcd for C30H36F2 [M]þ:
434.27786; found 434.278396.
3.3.13. 1,3-Difluoro-2,4,5,6-tetra(hex-1-ynyl)benzene (4d). Starting
with 3 (100 mg, 0.16 mmol), 1-hexyne (65 mg, 0.80 mmol), CuI
(5 mol %), X-Phos (10 mol %), Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv)
and 1,4-dioxane (5 mL), 4d was isolated as a dark brown oil (59 mg,
83%). 1H NMR (300 MHz, CDCl3):
d
¼0.79e0.91 (m, 12H, CH3),
1.06e1.21 (m, 3H, CH2), 1.38e1.58 (m, 15H, CH2), 2.39e2.47 (m, 6H,
CH2). 13C NMR (75.4 MHz, CDCl3):
3.3.10. 1,3-Difluoro-2,4,5,6-tetra(phenylethynyl)benzene (4a). Starting
with 3 (100 mg, 0.16 mmol), phenylacetylene (83 mg, 0.81 mmol), CuI
(5 mol %), X-Phos (10 mol %), Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and
1,4-dioxane (5 mL), 4a was isolated as orange solid (68 mg; 81%). Mp
d
¼13.6 (CH3), 13.6 (2CH2), 13.7
(CH3), 19.5 (2CH2), 19.6 (CH2), 19.7 (CH2), 21.8 (3CH2), 21.9 (CH2),
30.4 (CH2), 30.6 (2CH2), 30.7 (CH2), 71.7 (C), 77.2 (C), 99.5 (2C), 99.6
(C^C), 101.5 (C^C), 102.4 (C^C), 102.5 (C^C), 162.0 (d,
JCF¼255.7 Hz, CF), 162.3 (d, JCF¼255.7 Hz, CF). 19F NMR (282 MHz,
~
155e157 ꢀC. 1H NMR (300 MHz, CDCl3):
d
¼7.51e7.56 (m, 12H, ArH),
7.27e7.33 (m, 8H, ArH). 13C NMR (75.4 MHz, CDCl3):
d
¼75.5 (C^C),
CDCl3):
d
¼ꢁ103.9 (CF). IR (ATR, cmꢁ1):
¼2957 (m), 2931 (m), 2871
n
80.3 (C^C), 86.2 (C^C), 98.9 (C^C),101.3 (t, J¼2.6 Hz, C),101.4 (C),111.3
(C),111.5 (d, J¼7.5 Hz, C),122.2 (C),122.6 (C),122.7 (C),128.5 (6CH),128.6
(CH),129.1 (CH),129.4(d, J¼3.5Hz,CH),131.8(2CH),132.0(CH),161.5(d,
JCF¼260.4 Hz, CF), 161.7 (d, JCF¼260.4 Hz, CF). 19F NMR (282 MHz,
~
(w), 2234 (w), 1718 (w), 1599 (w), 1445 (s), 1378 (w), 1318 (w), 1260
(w), 1168 (w), 1104 (w), 1025 (m), 876 (w), 801 (w), 725 (w), 555
(w). UVevis (CH2Cl2) lmax: 251, 260, 380, 300 nm. Fluorescence
(CH2Cl2, lexcitation¼350 nm): lmax (emission)¼359, 370 nm. MS (EI,
70 eV); m/z (%)¼434 (100) [M]þ, 391 (10), 377 (14), 363 (10), 349
(19), 335 (25), 321 (19), 307 (15), 295 (11), 281 (14), 277 (10), 275
(13), 257 (10), 105 (13), 71 (12), 57 (22), 44 (19), 43 (26), 40 (21)
cmꢁ1. HRMS (EI) calcd for C30H36F2 [M]þ: 434.27796; found
434.278900.
CDCl3):
d
¼ꢁ100.42 (CF). IR (ATR, cmꢁ1):
¼3051 (m), 2205 (m), 1887
n
(w), 1596 (m), 1489 (m), 1441 (m), 1352 (m), 1268 (w), 1214 (m), 1156
(w),1094 (m),1067 (m), 998 (w), 939 (m), 747 (s), 684 (s), 578 (m), 529
(m), 498 (m), 436 (m) cmꢁ1. UVevis (CH2Cl2) lmax: 228, 255, 305,
345 nm. Fluorescence (CH2Cl2, lexcitation¼350 nm): lmax (emission)¼
400, 409 nm. MS (EI, 70 eV); m/z (%)¼514 (75) [M]þ, 69 (29), 44 (100).
HRMS (EI) calcd for C38H20F2 [M]þ: 514.15276; found 514.154168. Anal.
Calcd for C38H20F2: C, 88.70. H, 3.92. Found: C, 88.75. H, 3.66.
3.3.14. 1,4-Difluoro-2,3,5,6-tetra(3-methylphenylethynyl)-benzene
(6a). Starting with 5 (100 mg, 0.16 mmol), 3-methylphenyl-
acetylene (92 mg, 0.80 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and 1,4-dioxane (5 mL), 6a was
isolated as a yellow solid (79 mg, 85%). Mp 198e200 ꢀC. 1H NMR
3.3.11. 1,3-Difluoro-2,4,5,6-tetrakis(4-methoxylphenylethynyl)-ben-
zene (4b). Starting with
3
(100 mg, 0.16 mmol), 4-
methoxyphenylacetylene (128 mg, 0.97 mmol), CuI (5 mol %), X-
Phos (10 mol %), Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and DMF
(5 mL), 4b was isolated as a yellow solid (69 mg; 68%). Mp
(300 MHz, CDCl3):
(m, 8H, ArH). 13C NMR (75.4 MHz, CDCl3):
(2C^C), 101.4 (2C^C), 114.9 (C), 115.1 (d, J¼8.1 Hz, C), 122.3 (C),
d
¼2.27 (s,12H, CH3), 7.12e7.21 (m, 8H, ArH), 7.30
d
¼21.2 (4CH3), 80.8

M. Sharif et al. / Tetrahedron 69 (2013) 174e183
181
128.4 (4CH), 129.0 (4CH), 130.2 (2CH), 132.6 (4CH), 138.2 (C), 158.3
(w), 1105 (w), 1025 (w), 944 (w), 821 (w), 792 (w), 718 (w), 660 (w),
643 (w), 628 (w), 594 (w), 531 (m). MS (EI, 70 eV); m/z (%)¼634 (70)
[M]þ, 396 (15), 119 (25), 91 (25), 69 (10), 57 (14), 55 (11), 44 (100),
41 (15). HRMS (EI) calcd for C42H28F2O4 [M]þ: 634.19502; found
634.197451.
(d, JCF¼253.5 Hz, CF),158.6 (d, JCF¼253.5 Hz, CF). 19F NMR (282 MHz,
~
n
¼2917 (w), 2206 (w), 1769
CDCl3):
d
¼ꢁ108.69 (CF). IR (ATR, cmꢁ1):
(w), 1599 (w), 1485 (w), 1444 (w), 1408 (w), 1346 (w), 1273 (w),
1089 (w), 1038 (w), 961 (w), 874 (w), 774 (m), 683 (m), 587 (w), 537
(w), 441 (m), 394 (w) cmꢁ1. UVevis (CH2Cl2) lmax: 228, 313,
378 nm. Fluorescence (CH2Cl2, lexcitation¼350 nm): lmax
(emission)¼409 nm. MS (EI, 70 eV); m/z (%)¼570 (100) [M]þ. HRMS
(EI) calcd for C42H28F2 [M]þ: 570.21536; found 570.21536. Anal.
Calcd for C42H28F2: C, 88.40. H, 4.95. Found: C, 88.36. H, 4.91.
3.3.18. 1,4-Difluoro-2,3,5,6-tetra(hex-1-ynyl)benzene (6e). Starting
with 5 (100 mg, 0.16 mmol), 1-hexyne (65 mg, 0.80 mmol), CuI
(5 mol %), X-Phos (10 mol %), Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv)
and 1,4-dioxane (5 mL), 6e was isolated as a brown solid (59 mg,
83%). Mp 66e68 ꢀC. 1H NMR (300 MHz, CDCl3):
d
¼0.87 (t, J¼7.0 Hz,
3.3.15. 1,4-Difluoro-2,3,5,6-tetra(4-n-propylphenylethynyl)-benzene
(6b). Starting with 5 (100 mg, 0.16 mmol), 4-n-propylphenylace-
tylene (115 mg, 0.80 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and 1,4-dioxane (5 mL), 6b was
isolated as yellow solid (96 mg, 86%). Mp 189e191 ꢀC. 1H NMR
12H, CH3), 1.38e1.59 (m, 16H, CH2), 2.43 (t, J¼6.7 Hz, 8H, CH2). 13
C
NMR (75.4 MHz, CDCl3):
d
¼13.6 (4CH3), 19.6 (4CH2), 21.9 (4CH2),
30.5 (4CH2), 72.3 (t, J¼2.0 Hz, 2C^C),101.9 (t, J¼2.3 Hz, 2C^C),114.7
(d, J¼8.8 Hz, C), 114.9 (d, J¼9.2 Hz, C), 159.0 (d, JCF¼249.8 Hz, CF),
159.3 (d, JCF¼249.8 Hz, CF). 19F NMR (282 MHz, CDCl3):
d
¼ꢁ111.10
(CF). IR (ATR, cmꢁ1):
~
n
¼2952 (m), 2930 (m), 2865 (w), 2231 (w),1707
(300 MHz, CDCl3):
d
¼0.85 (t, J¼7.3 Hz, 12H, CH3), 1.51e1.61 (m, 8H,
CH2), 2.52 (t, J¼7.8 Hz, 8H, CH2), 7.08 (dt, J¼6.5, 2.0 Hz, 8H, ArH),
(w), 1463 (m), 1441 (s), 1420 (m), 1374 (w), 1315 (w), 1265 (w), 1106
(w), 1029 (w), 974 (w), 926 (w), 888 (w), 840 (w), 740 (w), 688 (w),
553 (w), 518 (w), 446 (w), 419 (w) cmꢁ1. UVevis (CH2Cl2) lmax: 227,
7.42 (dt, J¼6.5, 2.0 Hz, 8H, ArH). 13C NMR (75.4 MHz, CDCl3):
¼13.8
d
(4CH3), 24.4 (4CH2), 38.4 (4CH2), 80.6 (2C^C), 101.4 (2C^C), 114.8
(d, J¼8.7 Hz, C),114.9 (d, J¼8.4 Hz, C),128.7 (4CH),131.9 (4CH),144.3
(C), 158.4 (d, JCF¼253.6 Hz, CF), 158.7 (d, JCF¼253.6 Hz, CF). 19F NMR
~
258, 301, 314, 333, 351 nm. Fluorescence (CH2Cl2, lexcitation
¼
350 nm): lmax (emission)¼360, 380 nm. MS (EI, 70 eV); m/z (%)¼434
(100) [M]þ, 377 (19), 349 (10), 277 (10), 275 (10), 265 (10). HRMS (EI)
calcd for C30H36F2 [M]þ: 434.27796; found 434.278389.
(282 MHz, CDCl3):
d
¼ꢁ108.88 (CF). IR (ATR, cmꢁ1):
¼2957 (m),
n
2929 (m), 2868 (m), 2206 (m), 1904 (m), 1604 (m), 1510 (s),1442 (s),
1376 (m), 1344 (m), 1266 (m), 1201 (m), 1112 (m), 1018 (m), 944 (s),
868 (m), 800 (s), 709 (m), 645 (m), 566 (s), 524 (s), 440 (m) cmꢁ1
.
3.3.19. 1-Fluoro-2,3,4,5,6-pentakis(2-methylphenylethynyl)-benzene
(8a). Starting with 7 (100 mg, 0.16 mmol), 2-methylphenyl-
acetylene (95 mg, 0.82 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and DMF (5 mL), 8a was iso-
lated as a yellow solid (59 mg, 55%). Mp 128e130 ꢀC. 1H NMR
UVevis (CH2Cl2) lmax: 228, 317, 382 nm. Fluorescence (CH2Cl2,
lexcitation¼350 nm): lmax (emission)¼410, 421 nm. MS (EI, 70 eV);
m/z (%)¼682 (100) [M]þ, 284 (23). HRMS (EI) calcd for C50H44F2
[M]þ: 682.34056; found 682.339721. Anal. Calcd for C50H44F2: C,
87.94. H, 6.49. Found: C, 87.91. H, 6.45.
(300 MHz, CDCl3):
CH3), 7.04e7.17 (m, 15H, ArH), 7.21e7.49 (m, 5H, ArH). 13C NMR
(75.4 MHz, CDCl3):
d¼2.37 (s, 3H, CH3), 2.39 (s, 6H, CH3), 2.46 (s, 6H,
3.3.16. 1,4-Difluoro-2,3,5,6-tetra(4-n-pentylphenylethynyl)-benzene
(6c). Starting with 5 (100 mg, 0.16 mmol), 4-n-pentylphenylace-
tylene (137 mg, 0.80 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and 1,4-dioxane (5 mL), 6c was
isolated as a yellow solid (103 mg, 80%). Mp 114e116 ꢀC. 1H NMR
d
¼20.8, 20.9, 21.0, 29.7 (CH3), 85.2 (C^C), 85.3
(C^C), 90.7 (C^C), 99.1 (C^C), 122.4 (CH), 122.6 (CH), 125.5 (CH),
1125.6 (CH), 129.1 (d, J¼3.85 Hz, C), 132.2 (C), 132.4 (C), 140.6 (C),
140.8 (C), 140.9 (C), 155.9 (C), 157.9 (d, J¼233 Hz, CF). 19F NMR
(282 MHz, CDCl3):
d
¼ꢁ102.35. MS (EI, 70 eV): m/z (%)¼666 (100)
(300 MHz, CDCl3):
d
¼0.82 (t, J¼6.6 Hz,12H, CH3),1.24e1.27 (m, 14H,
[M]þ. HRMS (EI) calcd for C51H35F [M]þ: 666.271173; found
666.271113.
CH2), 1.50e1.60 (m, 10H, CH2), 2.56 (t, J¼7.6 Hz, 8H, CH2), 7.11 (dt,
J¼6.4, 1.9 Hz, 8H, ArH), 7.44 (dt, J¼6.4, 1.9 Hz, 8H, ArH). 13C NMR
(75.4 MHz, CDCl3):
d
¼14.1 (4CH3), 22.6 (4CH2), 30.9 (4CH2), 31.5
3.3.20. 1-Fluoro-2,3,4,5,6-pentakis(4-methylphenylethynyl)-benzene
(8b). Starting with 7 (100 mg, 0.14 mmol), 4-methylphenyl-
acetylene (95 mg, 0.82 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and DMF (5 mL), 8b was
isolated as yellow solid (63 mg, 69%). Mp 102e104 ꢀC. 1H NMR
(4CH2), 36.2 (4CH2), 80.6 (4C^C), 101.4 (4C^C), 114.7 (d, J¼8.7 Hz,
C), 114.9 (d, J¼10.0 Hz, C), 119.7 (C), 128.6 (4CH), 131.9 (4CH), 144.6
(C), 158.3 (d, JCF¼253.9 Hz, CF), 158.7 (d, JCF¼253.9 Hz, CF). 19F NMR
~
(282 MHz, CDCl3):
d
¼ꢁ108.90 (CF). IR (ATR, cmꢁ1):
¼3029 (w),
n
2956 (m), 2926 (m), 2853 (m), 2205 (m), 1898 (w), 1686 (w), 1605
(w), 1512 (m), 1441 (m), 1375 (w), 1347 (m), 1270 (w), 1177 (w), 1114
(w), 1018 (w), 946 (m), 829 (m), 804 (m), 746 (w), 656 (w), 571 (w),
538 (m), 493 (w), 441 (w) cmꢁ1. UVevis (CH2Cl2) lmax: 227, 316,
381 nm. Fluorescence (CH2Cl2, lexcitation¼350 nm): lmax
(emission)¼419 nm. MS (EI, 70 eV); m/z (%)¼794 (100) [M]þ, 682
(10), 681 (20), 284 (20), 69 (10), 44 (48). HRMS (EI) calcd for
C58H60F2 [M]þ: 794.46576; found 794.465121.
(300 MHz, CDCl3):
d
¼2.32 (s, 15H, CH3), 7.09e7.13 (m, 10H, ArH),
7.43e7.45 (m, 10H, ArH). 19F NMR (282 MHz, CDCl3):
d
¼ꢁ103.13. IR
(ATR, cmꢁ1):
n
~
¼3171 (w), 3077 (w), 3025 (w), 2952 (w), 2918 (w),
2856 (w), 2729 (w), 2204 (w), 1903 (w), 1726 (w), 1604 (w), 1115
(w), 1069 (w), 1019 (w), 985 (w), 961 (w), 945 (w), 932 (w), 811 (s),
741 (w), 721 (w), 706 (w), 690 (w), 659 (w), 645 (w), 526 (w). MS
(EI, 70 eV); m/z (%)¼666 (36) [M]þ, 397 (33), 396 (94), 394 (36), 331
(11), 329 (21), 277 (15), 210 (15), 198 (11), 186 (16), 44 (100). HRMS
(EI) calcd for C51H35F [M]þ: 666.27173; found 666.273441.
3.3.17. 1,4-Difluoro-2,3,5,6-tetrakis(4-methoxylphenylethynyl)-ben-
zene (6d). Starting with
5
(100 mg, 0.16 mmol), 4-
3.3.21. 1-Fluoro-2,3,4,5,6-penta(4-n-propylphenylethynyl)-benzene
(8c). Starting with 7 (100 mg, 0.13 mmol), 4-n-propylphenylace-
tylene (112 mg, 0.78 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and 1,4-dioxane (5 mL), 8c was
isolated as a dark brown solid (83 mg, 74%). Mp 85e87 ꢀC. 1H NMR
methoxyphenylacetylene (128 mg, 0.97 mmol), CuI (5 mol %), X-
Phos (10 mol %), Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and DMF
(5 mL), 6d was isolated as a yellow solid (80 mg, 78%). Mp
179e180 ꢀC. 1H NMR (300 MHz, CDCl3):
d
¼3.78 (s, 12H, OCH3), 6.83
(dt, J¼9.00 Hz, 8H, ArH), 7.47 (dt, J¼9.00 Hz, 8H, ArH). 13C NMR
(300 MHz, CDCl3):
d
¼0.82 (t, J¼7.3 Hz, 15H, CH3), 1.53e1.65 (m, 10H,
(75.4 MHz, CDCl3):
d
¼55.4 (OCH3), 80.2 (C^C), 101.1 (C^C), 114.2
CH2), 2.54 (t, J¼7.3 Hz, 10H, CH2), 7.10 (dd, J¼8.3, 4.0 Hz, 10H, ArH),
(CH), 114.7 (C), 132.2 (C), 133.5 (CH), 160.4 (C), 162.9 (d,
7.46 (dt, J¼8.0, 3.3 Hz, 10H, ArH). 13C NMR (75.4 MHz, CDCl3):
JCF¼257.2 Hz, CF). 19F NMR (282 MHz, CDCl3):
d¼ꢁ103.13. IR (ATR,
d¼13.8 (5CH3), 24.4 (5CH2), 38.1 (5CH2), 80.9 (C^C), 86.5 (C^C),
cmꢁ1):
n
¼2914 (w), 2847 (w), 2206 (w), 1604 (w), 1566 (w), 1513
86.6 (C^C), 100.4 (C^C), 100.6 (C^C), 114.5 (C), 120.0 (C), 120.2 (C),
120.5 (C), 128.7 (d, J¼2.0 Hz, 8CH), 143.7 (C), 144.1 (d, J¼1.4 Hz, C),
~
(w), 1467 (w), 1413 (w), 1376 (w), 1343 (w), 1292 (w), 1249 (w), 1170

182
M. Sharif et al. / Tetrahedron 69 (2013) 174e183
163.5 (d, JCF¼255.6 Hz, CF). 19F NMR (282 MHz, CDCl3):
d
¼ꢁ103.17
158.0 (d, JCF¼249.9 Hz, CF). 19F NMR (282 MHz, CDCl3):
d
¼ꢁ103.2
(CF). IR (ATR, cmꢁ1):
¼3025 (w), 2956 (w), 2868 (w), 2323 (w),
(CF). IR (ATR, cmꢁ1):
¼3025 (w), 2953 (w), 2922 (s), 2852 (m),
~
n
~
n
2205 (w), 1906 (w), 1671 (w), 1604 (m), 1509 (w), 1455 (s), 1376 (m),
1338 (w), 1257 (w), 1203 (w), 1178 (w), 1113 (w), 1090 (w), 1018 (w),
933 (w), 867 (w), 799 (w), 528 (w), 450 (w) cmꢁ1. UVevis (CH2Cl2)
lmax: 227, 337, 380 nm. Fluorescence (CH2Cl2, lexcitation¼350 nm):
lmax (emission)¼430 nm. MS (EI, 70 eV); m/z (%)¼806 (42) [M]þ.
HRMS (EI) calcd for C62H57F [M]þ: 806.42823; found 806.425932. *:
CF-group not resolved in 13C NMR.
2205 (w), 1903 (w), 1690 (w), 1604 (w), 1510 (w), 1462 (w), 1425
(m), 1375 (w), 1261 (w), 1177 (w), 1115 (w), 1070 (w), 1018 (w), 933
(w), 839 (m), 806 (m), 725 (m), 527 (m), 400 (m) cmꢁ1. UVevis
(CH2Cl2) lmax: 228, 259, 337, 378 nm. Fluorescence (CH2Cl2,
lexcitation¼350 nm): lmax (emission)¼440 nm. MS (EI, 70 eV); m/z
(%)¼1086 (10) [M]þ, 612 (14), 610 (10). HRMS (EI) calcd for C62H57
F
[M]þ not possible: *CF-group not resolved in 13C NMR. Anal. Calcd
for C62H57F: C, 88.14. H, 9.90. Found: C, 88.18. H, 9.93.
3.3.22. 1-Fluoro-2,3,4,5,6-pentakis(4-tert-butylphenylethynyl)-ben-
zene (8d). Starting with 7 (100 mg, 0.16 mmol), 4-butylphenyl-
acetylene (129 mg, 0.82 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and DMF (5 mL), 8d was
isolated as a yellow solid (96 mg, 68%). Mp 161e163 ꢀC. 1H NMR
3.3.25. 1-Fluoro-2,3,4,5,6-pentakis(4-methoyphenylethynyl)-ben-
zene (8g). Starting with 7 (100 mg, 0.16 mmol), 4-methox-
yphenylacetylene (108 mg, 0.82 mmol), CuI (5 mol %), X-Phos
(10 mol %), Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and DMF (5 mL),
8g was isolated as a yellow solid (94 mg, 78%). Mp 151e153 ꢀC. 1H
(300 MHz, CDCl3):
CH3), 7.31e7.35 (m, 10H, ArH), 7.48e7.51 (m, 10H, ArH). 13C NMR
(75.4 MHz, CDCl3):
d¼1.28 (s, 27H, CH3), 1.29 (s, 9H, CH3), 1.48 (s, 9H,
NMR (300 MHz, CDCl3):
6.79e6.84 (m, 10H, ArH), 7.45e7.48 (m, 10H, ArH). 13C NMR
(75.4 MHz, CDCl3):
d
¼3.77 (s, 6H, OCH3), 3.78 (s, 9H, OCH3),
d
¼31.2 ((CH3)3C), 34.9 (C(CH3)3), 80.3 (C^C),
80.9 (C^C), 83.3 (C^C), 86.2 (C^C), 89.8 (C^C), 100.3 (C^C),
100.5 (C^C), 119.8 (C), 120.1 (C), 125.5 (CH), 125.6 (CH), 131.5 (C),
131.6 (C), 131.7 (C), 152.0 (C), 152.4 (C).*19F NMR (282 MHz, CDCl3):
d
¼55.4 (2OCH3), 55.5 (2OCH3), 80.5 (C^C),
100.1 (C^C), 100.2 (C^C), 114.1 (CH), 114.2 (CH), 115.0 (C), 115.5
(C), 116.6 (C), 133.2 (CH), 133.3 (CH), 160.0 (C), 160.2 (C), 160.9*.
d
¼ꢁ103.10. IR (ATR, cmꢁ1): ¼3082 (w), 3033 (w), 2958 (w), 2902
19F NMR (282 MHz, CDCl3):
d
¼ꢁ103.84. IR (ATR, cmꢁ1): ¼3045
~
n
~
n
(w), 2866 (w), 2205 (w), 1605 (w), 1513 (w), 1504 (w), 1462 (w),
1406 (w), 1361 (w), 1267 (w), 1201 (w), 1107 (w), 1016 (w), 934 (w),
876 (w), 831 (m), 736 (w), 665 (w), 614 (w), 559 (w). MS (EI, 70 eV);
m/z (%)¼876 (17) [M]þ, 207 (11), 97 (10), 69 (23), 44 (100). HRMS
(EI): calcd for C66H65F [M]þ: 876.50648; found 876.513743. Anal.
Calcd for C66H65F: C, 90.37. H, 7.47. Found: C, 90.35. H, 6.70. *: CF-
group not resolved in 13C NMR.
(w), 2999 (w), 2954 (w), 2835 (w), 2536 (w), 2203 (w), 1715 (w),
1603 (m), 1565 (w), 1505 (s), 1455 (m), 1413 (w), 1361 (w), 1288
(m), 1243 (s), 1167 (s), 1104 (m), 1024 (m), 932 (m), 825 (s), 717
(w), 665 (w), 642 (w), 627 (w), 531 (m). MS (EI, 70 eV); m/z (%)¼
746 (100) [M]þ, 135 (10), 57 (15). HRMS (EI) calcd for C51H35O5F
[M]þ: 746.24630; found 746.248188. *: CF-group not resolved in
13C NMR.
3.3.23. 1-Fluoro-2,3,4,5,6-penta(4-n-pentylphenylethynyl)-benzene
(8e). Starting with 7 (100 mg, 0.13 mmol), 4-n-pentylphenylace-
tylene (142 mg, 0.82 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and 1,4-dioxane (5 mL), 8e was
isolated as a dark brown oil (103 mg, 79%). 1H NMR (300 MHz,
Acknowledgements
Financial support by the DAAD, by the State of Pakistan and by
the State of Mecklenburg-Vorpommern (scholarships for M.S.) and
by the University of Rostock (INF scholarship for S.R.) is gratefully
CDCl3):
d
¼0.83 (t, J¼6.5 Hz, 15H, CH3), 1.24e1.28 (m, 20H, CH2),
ꢀ
acknowledged. The work was also supported by the TAMOP-4.2.1/
1.53e1.61 (m, 10H, CH2), 2.56 (t, J¼7.7 Hz, 10H, CH2), 7.10 (dd, J¼8.3,
B-09/KONV-2010-007 project. The project is implemented through
the New Hungary Development Plan, co-financed by the European
Social Fund and the European Regional Development Fund.
4.7 Hz, 10H, ArH), 7.46 (dt, J¼8.0, 3.0 Hz, 10H, ArH). 13C NMR
(75.4 MHz, CDCl3):
d
¼14.1 (5CH3), 22.5 (CH2), 30.9 (CH2), 31.0 (CH2),
36.3 (CH2), 80.9 (C^C), 86.1 (C^C), 86.5 (C^C), 86.6 (C^C), 97.8
(C^C), 100.4 (C), 100.5 (d, J¼5.1 Hz, C), 114.2 (C), 114.4 (C), 120.0 (C),
120.2 (C), 120.5 (C), 128.6 (d, J¼2.8 Hz, 8CH), 131.7 (4CH), 131.9 (d,
J¼3.3 Hz, 8CH), 144.0 (C), 144.3 (d, J¼1.8 Hz, C), 161.1 (d,
References and notes
JCF¼256.0 Hz, CF). 19F NMR (282 MHz, CDCl3):
d
¼ꢁ103.17 (CF). IR
1. (a) Bunz, U. H. F.; Rubin, Y.; Tobe, Y. Chem. Soc. Rev. 1999, 28, 107; (b) Diederich,
F. Nature 1994, 369, 199.
2. (a) Ebert, M.; Jungbauer, D. A.; Kleppinger, R.; Wendorff, J. H.; Kohne, B.;
Praefcke, K. Liq. Cryst. 1989, 4, 53; (b) Kumar, S.; Varshney, S. K. Angew. Chem.,
Int. Ed. 2000, 39, 3140.
(ATR, cmꢁ1):
¼3025 (w), 2953 (w), 2924 (m), 2854 (m), 2206 (w),
~
n
1908 (w), 1679 (w), 1605 (w), 1510 (m), 1455 (m), 1376 (w), 1260
(w), 1178 (w), 1113 (w), 1070 (w), 1018 (w), 968 (w), 897 (w), 813
(m), 727 (w), 529 (m), 444 (w), 403 (w) cmꢁ1. UVevis (CH2Cl2) lmax
:
3. Kondo, K.; Yasuda, S.; Sakaguchi, T.; Miya, M. J. Chem. Soc., Chem. Commun.
1995, 55.
228, 260, 337, 378 nm. Fluorescence (CH2Cl2, lexcitation¼350 nm):
lmax (emission)¼440 nm. MS (EI, 70 eV); m/z (%)¼946 (10) [M]þ,
448 (13), 432 (19), 403 (10), 69 (13), 44 (100). HRMS (EI) calcd for
C72H77F [M]þ: 946.58473; found 946.583714.
4. (a) Kehoe, J. M.; Kiley, J. H.; English, J. J.; Johnson, C. A.; Petersen, R. C.; Haley, M.
M. Org. Lett. 2000, 2, 969; (b) Wan, W. B.; Brand, S. C.; Pak, J.; Haley, M. M. Chem.
dEur. J. 2000, 6, 2044 For recent reviews, see: (c) Haley, M. M. Synlett 1998,
557; (d) Haley, M. M.; Wan, W. B. In Advances in Strained and Interesting Organic
Molecules; Halton, B., Ed.; JAI: New York, NY, 2000; Vol. 8, p 1.
5. (a) Gray, G. W.; Hird, M.; Toyne, K. Liq. Cryst. 1991, 195, 221; (b) Lincker, F.;
Bourgun, P.; Masson, P.; Dider, P.; Guidoni, L.; Bigot, J. Y.; Nicoud, J. F.; Donnio,
B.; Guillon, D. Org. Lett. 2005, 7, 1505; (c) Kraft, A.; Grimsdale, A. C.; Holmes, A.
B. Angew. Chem., Int. Ed. 1998, 37, 402; (d) Lo, S. C.; Burn, P. L. Chem. Rev. 2007,
107, 1097; (e) Fichou, D. J. Mater. Chem. 2000, 10, 571; (f) Funahashi, M.; Zhang,
F.; Tamaoki, N. Adv. Mater. (Weinheim, Ger.) 2007, 19, 353; (g) Yu, G.; Gao, J.;
Hummelen, J. C.; Wudl, F.; Heeger, A. J. Science 1995, 270, 1789; (h) Denk, W.;
Strickler, J. H.; Webb, W. W. Science 1990, 248, 73.
3.3.24. 1-Fluoro-2,3,4,5,6-penta(4-n-heptylphenylethynyl)-benzene
(8f). Starting with 7 (100 mg, 0.13 mmol), 4-n-heptylphenylace-
tylene (165 mg, 0.82 mmol), CuI (5 mol %), X-Phos (10 mol %),
Pd(OAc)2 (5 mol %), Cs2CO3 (5 equiv) and 1,4-dioxane (5 mL), 8f was
isolated as a yellow-brown oil (95 mg, 63%). 1H NMR (300 MHz,
CDCl3):
d
¼0.81 (t, J¼6.6 Hz, 15H, CH3), 1.21e1.26 (m, 30H, CH2),
6. Itami, K.; Yamazaki, D.; Yoshida, J.-I. J. Am. Chem. Soc. 2004, 126, 15396; (b) Lin,
Y.-C.; Lai, C. K.; Chang; Liu, K. T. Liq. Cryst. 2002, 29, 237.
1.49e1.60 (m, 20H, CH2), 2.56 (t, J¼7.7 Hz, 10H, CH2), 7.10 (d,
J¼255.6 Hz, 10H, ArH), 7.46 (dt, J¼8.3, 3.0 Hz, 10H, ArH). 13C NMR
7. (a) Bryce, M. R.; Marshallsay, G. J.; Moore, A. J. J. Org. Chem. 1992, 57, 4859; (b)
ꢀ
Fourmigue, M.; Johannsen, I.; Boubekeur, K.; Nelson, C.; Batail, P. J. Am. Chem. Soc.
(75.4 MHz, CDCl3):
d
¼14.1 (5CH3), 22.7 (5CH2), 29.2 (5CH2), 31.3
1993, 115, 3752; (c) Bunz, U. H. F.; Enkelmann, V. Organometallics 1994, 13, 3823;
(d) Iyoda, M.; Fukuda, M.; Yoshida, M.; Sasaki, M. S. Chem. Lett. 1994, 2369.
8. Kayser, B.; Altman, J.; Beck, W. Chem.dEur. J. 1999, 5, 754.
9. Ito, S.; Inabe, H.; Morita, N.; Ohta, K.; Kitamura, T.; Imafuku, K. J. Am. Chem. Soc.
2003, 125, 1669.
(5CH2), 31.8 (CH2), 36.3 (CH2), 80.9 (CH2),100.4 (C^C),100.6 (C^C),
119.9 (C^C), 120.2 (C^C), 120.5 (C^C), 128.0 (d, J¼2.5 Hz, 8CH),
129.3 (C), 131.5 (2C), 131.6 (2C), 131.7 (4CH), 131.8 (d, J¼2.5 Hz, 8CH),
134.5 (d, J¼4.1 Hz, 2C), 142.8 (2C), 143.9 (2C), 144.4 (d, J¼1.3 Hz, 4C),
10. Hasegawa,M.;Enozawa,H.;Kawabata, Y.; Iyoda,M. J. Am.Chem.Soc. 2007,129, 3072.

M. Sharif et al. / Tetrahedron 69 (2013) 174e183
11. (a) Kamada, K.; Antonov, L.; Yamada, S.; Ohta, K.; Yoshimura, T.; Tahara, K.;
183
Med. Chem. 1991, 34, 2857; (j) Albrecht, H. A.; Beskid, G.; Christenson, J. G.;
Deitcher, K. H.; Georgopapadakou, N. H.; Keith, D. D.; Konzelmann, F. M.;
Pruess, D. L.; Wie, C. C. J. Med. Chem. 1994, 37, 400; (k) Song, C. W.; Lee, K. Y.;
Kim, C. D.; Chang, T.-M.; Chey, W. Y. J. Pharmacol. Exp. Ther. 1997, 281, 1312; (l)
De Voss, J. J.; Sui, Z.; DeCamp, D. L.; Salto, R.; Babe, L. M.; Craik, C. S.; Ortiz de
Montellano, P. R. J. Med. Chem. 1994, 37, 665; (m) Anjaiah, S.; Chandrasekhar,
S.; Gree, R. Adv. Synth. Catal. 2004, 346, 1329; (n) Iorio, M. A.; Paszkowska, R.
T.; Frigeni, V. J. Med. Chem. 1987, 30, 1906; (o) Popp, J. L.; Musza, L. L.; Barrow,
C. J.; Rudewicz, P. J.; Houck, D. R. J. Antibiot. 1994, 47, 411; (p) Chen, T. S.;
Petuch, B.; MacConnell, J.; White, R.; Dezeny, G. J. Antibiot. 1994, 47, 1290; (q)
Lam, K. S.; Schroeder, D. R.; Veitch, J. M.; Colson, K. L.; Matson, J. A.; Rose, W.
C.; Doyle, T. W.; Forenza, S. J. Antibiot. 2001, 54, 1.
Inaba, A.; Sonoda, M.; Tobe, Y. ChemPhysChem 2007, 8, 2671; (b) Ha-Thi,
ˇ
M.-H.;
ꢀ
Souchon, V.; Hamdi, A.; Metivier, A. R. V.; Nakatani, K. P.; Lacroix, G.; Genet, J.-P.;
Michelet, V.; Leray, I. Chem.dEur. J. 2006, 12, 9056.
12. (a) Sonoda, M.; Inabe, A.; Itahashi, K.; Tobe, Y. Org. Lett. 2001, 3, 2419; (b)
Kobayashi, K.; Kobayashi, N. J. Org. Chem. 2004, 69, 2487.
13. (a) Tobe, Y.; Kubota, K.; Naemura, K. J. Org. Chem. 1997, 62, 3430; (b)
Tovar, J. D.; Jux, N.; Jarrosson, T.; Khan, S. I.; Rubin, Y. J. Org. Chem. 1997,
62, 3432.
14. Anthony, J. E.; Khan, S. I.; Rubin, Y. Tetrahedron Lett. 1997, 38, 3499.
15. Bowls, D. M.; Palmer, G. J.; Landis, C. A.; Scott, J. L.; Anthony, J. E. Tetrahedron
2001, 57, 3753.
16. Diercks, R.; Armstrong, J. C.; Boese, R.; Vollhardt, K. P. C. Angew. Chem., Int. Ed.
18. Reviews: (a) Tredwell, M.; Gouverneur, V. Org. Biomol. Chem. 2006, 4, 26; (b)
Ma, J.-A.; Cahard, D. Chem. Rev. 2004, 104, 6119; (c) Singh, R. P.; Shreeve, J. M.
Synthesis 2002, 17, 2561; (d) Taylor, S. D.; Kotoris, C. C.; Hum, G. Tetrahedron
1999, 55, 12431; (e) Purrington, S. T.; Kagen, B. S.; Patrick, T. B. Chem. Rev. 1986,
86, 997; (f) Nyffeler, P. T.; Duron, S. G.; Burkart, M. D.; Vincent, S. P.; Wong, C.-H.
Angew. Chem., Int. Ed. 2005, 44, 192; (g) Singh, R. P.; Shreeve, J. M. Acc. Chem. Res.
2004, 37, 31.
19. Rahman, M. A.; Shito, F.; Kitamura, T. Synthesis 2010, 27.
20. U.S. Patent 5,386,069, 31.1.1995.
21. Ehlers, P.; Neubauer, A.; Lochbrunner, S.; Villinger, A.; Langer, P. Org. Lett. 2011,
13, 1618.
Engl. 1986, 25, 268.
17. (a) Fluorine in Bioorganic Chemistry; Filler, R., Kobayasi, Y., Yagupolskii, L. M.,
Eds.; Elsevier: Amsterdam, 1993; (b) Filler, R. Fluorine Containing Drugs in
Organofluorine Chemicals and Their Industrial Application; Pergamon: New
York, NY, 1979, Chapter 6; (c) Hudlicky, M. Chemistry of Organic Compounds;
Ellis Horwood: Chichester, UK, 1992; (d) Kirsch, P. Modern Fluoroorganic
Chemistry; VCH: Weinheim, 2004; (e) Chambers, R. D. Fluorine in Organic
Chemistry; Blackwell Publishing CRC: 2004; See also: (f) Ryckmanns, T.;
Balancon, L.; Berton, O.; Genicot, C.; Lamberty, Y.; Lallemand, B.; Passau, P.;
ꢀ ꢀ
Pirlot, N.; Quere, L.; Talaga, P. Bioorg. Med. Chem. Lett. 2002, 12, 261; (g)
Malamas, M. S.; Sredy, J.; Moxham, C.; Katz, A.; Xu, W.; McDevitt, R.; Ade-
bayo, F. O.; Sawicki, D. R.; Seestaller, L.; Sullivan, D.; Taylor, J. R. J. Med. Chem.
2000, 43, 1293; (h) Ciha, A. J.; Ruminski, P. G. J. Agric. Food Chem. 1991, 39,
2072; (i) Albrecht, H. A.; Beskid, G.; Georgopapadakou, N. H.; Keith, D. D.;
Konzelmann, F. M.; Pruess, D. L.; Rossman, P. L.; Wei, C. C.; Christenson, J. G. J.
22. CCDC-908403e908406 and CCDC-905527 contain all crystallographic details
of this publication and is available free of charge at www.ccdc.cam.ac.uk/
conts/retrieving.html or can be ordered from the following address:
Cambridge Crystallographic Data Centre, 12 Union Road, GB-Cambridge
CB21EZ; Fax: (þ44)1223-336-033; or deposit@ccdc.cam.ac.uk.