Synthesis, structures, and optical properties of heteroarene-fused dispiro compounds

Article abstract of DOI:10.1021/jo902482n

(Chemical Equation Presented) Novel heteroarene-fused dispiro compounds, dispiro[9H-fluorene-9,5′(6′H)-diindeno[1,2-b:2′,1′-d] -furan-6′,9″-[9H]fluorene] (dsp-DIF), dispiro[9H-fluorene-9, 5′(6′H)-diindeno[1,2-b:2′,1′-d]thiophene-6′, 9″-[9H]fluorene] (dsp-

Full text of DOI:10.1021/jo902482n

pubs.acs.org/joc
Synthesis, Structures, and Optical Properties of Heteroarene-Fused
Dispiro Compounds
Toshiyuki Kowada, Toshihisa Kuwabara, and Kouichi Ohe*
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering,
Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
ohe@scl.kyoto-u.ac.jp
Received November 26, 2009
Novel heteroarene-fused dispiro compounds, dispiro[9H-fluorene-9,50(60H)-diindeno[1,2-b:20,10-d]-
furan-60,900-[9H]fluorene] (dsp-DIF), dispiro[9H-fluorene-9,50(60H)-diindeno[1,2-b:20,10-d]thiophene-
60,900-[9H]fluorene] (dsp-DIT), and 11-phenyldispiro[9H-fluorene-9,50(60H)-diindeno[1,2-b:20,10-d]pyrrole-
60,900-[9H]fluorene] (dsp-DIP-Ph) have been synthesized. Their structures were unambiguously determined
by X-ray crystallography. These three dispiro compounds showed blue fluorescence with moderate
quantum yields.
Introduction
great interest as potential components of such organic
electronic devices because of their high coplanarity, intense
luminescence, and carrier mobility.4,5 Since the first synthesis
of ladder-type poly(p-phenylene)s in 1991,4a there have been
many efforts to clarify their structure-property relation-
ships by using structurally defined conjugated oligomers.
Among them, 6,12-dihydroindeno[1,2-b]fluorene (IF) is one
of the simplest ladder-type oligomers and regarded as a
promising building block for OLEDs and OFETs (Figure 1).5
On the other hand, the physical properties of ladder-type
compounds can be modulated by incorporating heteroatoms
as bridging atoms of the π-backbone4b,c,5d,6 or incorporating
Conjugated polymers and oligomers have attracted con-
siderable attention in recent years as organic semiconductors
for application in devices such as organic light-emitting
diodes (OLEDs),1 organic field-effect transistors (OFETs),2
and solar cells.3 In particular, ladder-type materials are of
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Published on Web 01/07/2010
DOI: 10.1021/jo902482n
r
2010 American Chemical Society

Kowada et al.
JOCArticle
FIGURE 1. Structures of IF and DIT derivatives and the corresponding dispiro compounds.
heteroarenes directly as components of the π-backbone.4g,7,8
Indeed, 10,11-dihydrodiindeno[1,2-b:20,10-d]thiophene (DIT)
derivatives, in which the central benzene ring of IF is replaced
by a thiophene ring, show relatively high hole mobilities.7c
Recently, much attention has been paid to the construction
of ladder-type compounds with rigid spiro structures
(Figure 1).4c,6b,9-11 However, to the best of our knowledge,
ladder-type compounds involving both heteroarenes and spiro
structures have been less investigated.7b
SCHEME 1. Synthetic Route to sp-FIF and sp-FIT
Recently, furan- or thiophene-containing spiro compounds,
sp-FIF and sp-FIT, have been newly synthesized in our labo-
ratory (Scheme 1).12 Then, we envisioned that novel hetero-
arene-fused ladder-type compounds could be synthesized
SCHEME 2. Synthetic Route to Dispiro Compounds
(7) (a) Wong, K.-T.; Chao, T.-C.; Chi, L.-C.; Chu, Y.-Y.; Balaiah, A.;
Chiu, S.-F.; Liu, Y.-H.; Wang, Y. Org. Lett. 2006, 8, 5033. (b) Xie, L.-H.;
Hou, X.-Y.; Tang, C.; Hua, Y.-R.; Wang, R.-J.; Chen, R.-F.; Fan, Q.-L.;
Wang, L.-H.; Wei, W.; Peng, B.; Huang, W. Org. Lett. 2006, 8, 1363.
(c) Chao, T.-C.; Wong, K.-T.; Hung, W.-Y.; Hou, T.-H.; Chen, W.-J.
Tetrahedron Lett. 2009, 50, 3422. (d) Jiang, Z.; Yao, H.; Liu, Z.; Yang, C.;
Zhong, C.; Qin, J.; Yu, G.; Liu, Y. Org. Lett. 2009, 11, 4132.
based on an intramolecular Friedel-Crafts-type alkylation.
Herein, we report the synthesis, structures, and optical
properties of unique dispiro compounds containing hetero-
les, such as furan, thiophene, or pyrrole (Scheme 2).
€
(8) (a) Baierweck, P.; Simmross, U.; Mullen, K. Chem. Ber. 1988, 121,
2195. (b) Graham, J.; Ninan, A.; Reza, K.; Sainsbury, M.; Shertzer, H. G.
Tetrahedron 1992, 48, 167. (c) Brown, D. W.; Mahon, M. F.; Ninan, A.
Tetrahedron 1993, 49, 8919.
(9) Bent-type diindenothiophene (2,11-dihydrodiindeno[2,1-b:10,20-d]thio-
phene) derivatives have been reported. See ref 7b.
(10) For IF derivatives with spiro linkage, see: (a) Cocherel, N.; Poriel,
Results and Discussion
ꢁ
C.; Rault-Berthelot, J.; Barriere, F.; Audebrand, N.; Slawin, A. M. Z.;
Vignau, L. Chem.;Eur. J. 2008, 14, 11328. (b) Chi, L.-C.; Hung, W.-Y.;
Chiu, H.-C.; Wong, K.-T. Chem. Commun. 2009, 3892. (c) Poriel, C.; Liang,
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J.-J.; Rault-Berthelot, J.; Barriere, F.; Cocherel, N.; Slawin, A. M. Z.;
Horhant, D.; Virboul, M.; Alcaraz, G.; Audebrand, N.; Vignau, L.; Huby,
Scheme 3 shows the synthetic route to dispiro[9H-fluo-
rene-9,50(60H)-diindeno[1,2-b:20,10-d]furan-60,900-[9H]fluorene]
(dsp-DIF). In the first step, lithiation of 1,2-dibromobenzene
followed by reaction with 9-fluorenone afforded the alcohol
1 in 94% yield, which was converted to the corresponding
silyl ether derivative 2 (96%). The Stille coupling reaction of
2 with 2,5-bis(trimethylstannyl)furan afforded 3 in 85% yield.
Deprotection of 3 produced the precursor diol 4 in 76% yield.
The conversion of the diol 4 to dsp-DIF is sensitive to the
reaction conditions. A typical method for constructing the
N.; Wantz, G.; Hirsch, L. Chem.;Eur. J. 2007, 13, 10055. (d) Thirion, D.;
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Poriel, C.; Barriere, F.; Metivier, R.; Jeannin, O.; Rault-Berthelot, J. Org.
Lett. 2009, 11, 4794. (e) Horhant, D.; Liang, J.-J.; Virboul, M.; Poriel, C.;
Alcaraz, G.; Rault-Berthelot, J. Org. Lett. 2006, 8, 257. (f) Poriel, C.; Rault-
ꢁ
Berthelot, J.; Barriere, F.; Slawin, A. M. Z. Org. Lett. 2008, 10, 373. (g) Vak,
D.; Lim, B.; Lee, S.-H.; Kim, D.-Y. Org. Lett. 2005, 7, 4229.
(11) (a) Wu, Y.; Zhang, J.; Bo, Z. Org. Lett. 2007, 9, 4435. (b) Wu, Y.;
Zhang, J.; Fei, Z.; Bo, Z. J. Am. Chem. Soc. 2008, 130, 7192.
(12) (a) Kowada, T.; Matsuyama, Y.; Ohe, K. Synlett 2008, 1902.
(b) Kowada, T.; Ohe, K. Bull. Korean Chem. Soc. In press.
J. Org. Chem. Vol. 75, No. 3, 2010 907

Kowada et al.
JOCArticle
SCHEME 3. Synthesis of dsp-DIF
SCHEME 4. Synthesis of dsp-DIT
of diyne 10 with aniline. Furthermore, it was possible to trans-
form diyne 10 to thiophene 6, leading to dsp-DIT, by reaction
with Na2S 9H2O (Scheme 6). This result suggests that diyne 10
3
has great potential as a key structure to prepare various hetero-
arene-fused dispiro compounds.
spirofluorene skeleton is the acid-promoted Friedel-Crafts
reaction.13 Although several acids were tested for this reaction
at room temperature or 0 °C, only a trace amount of dsp-DIF
was detected by TLC analysis. Finally, dsp-DIF was isolated in
47% yield using methanesulfonic acid in CH2Cl2 at -78 °C.
The synthesis of dispiro[9H-fluorene-9,50(60H)-diindeno-
[1,2-b:20,10-d]thiophene-60,900-[9H]fluorene] (dsp-DIT) is depic-
ted in Scheme 4. The methoxy methyl ether 5 was obtained in
79% yield through protection of the alcohol 1 with chlorodi-
methyl ether. The Stille coupling reaction between 2 equiv of 5
and 2,5-bis(trimethylstannyl)thiophene afforded 6 in 33%
yield. The reaction of 6 with 10% aq HCl in acetic acid afforded
dsp-DIT as a result of the reaction cascade with a deprotection
and intramolecular double Friedel-Crafts alkylation.
To prepare a pyrrole analogue of dsp-DIF and dsp-DIT,
we first examined the Stille coupling reaction of 5 with
N-methyl-2,5-bis(trimethylstannyl)pyrrole according to the
synthetic route of dsp-FIT. However, the reaction did not
proceed at all. Therefore, we employed another synthetic
route based on utilization of copper-catalyzed double hydro-
amination of a diyne (Scheme 5). The halogen-lithium
exchange reaction of 5 followed by quenching with molecu-
lar iodine gave 7, which was subsequently reacted with
trimethylsilylacetylene to afford 8 in 71% yield in two steps.
Deprotection of the silyl group of 8 gave alkyne 9, and Glaser
coupling gave diyne 10 in excellent yield (98 and 94%,
respectively). Finally, 11-phenyldispiro[9H-fluorene-9,50(60H)-
diindeno[1,2-b:20,10-d]pyrrole-60,900-[9H]fluorene] (dsp-DIP-Ph)
was obtained in 22% yield (in two steps) by acid-promoted
intramolecular Friedel-Crafts reaction of the major product,
which was produced by copper-catalyzed double hydroamination
Single crystals of dsp-DIF, dsp-DIT, and dsp-DIP-Ph were
grown by slow evaporation of solution of the compound in
CH2Cl2/hexane, toluene/hexane, and EtOAc/hexane at
room temperature, respectively. X-ray crystal structures of
dsp-DIF, dsp-DIT, and dsp-DIP-Ph are shown in Figure 2.
For dsp-DIF and dsp-DIP-Ph, the two fluorene rings are
favorably overlapped and fixed closely by the diindenofuran
skeleton. The longest distances between the two opposite carbon
˚
atoms of each fluorene skeleton are 4.828(15)-4.589(5) A,
while the distances between the two spiro carbon atoms are
˚
3.892(11)-3.831(3) A. On the other hand, for dsp-DIT, the
longest and shortest distances between two fluorene rings
˚
are 3.859(6) and 3.603(5) A, respectively, and the distance
˚
between two spiro carbon atoms is 3.709(4) A. This shorter
distance seems to be due to the longer C-S bond length of
˚
dsp-DIT by ca. 0.34 A than the C-O bond length of dsp-DIF
and the existence of an intramolecular π-π stacking inter-
action.14 It is noteworthy that the two fluorene units are
completely overlapped in the structure (Figure 2b). Diinde-
noheteroarene frameworks of three dispiro compounds exhi-
bit nearly planar structures, as found in the small dihedral angles
between the mean planes of the two benzene rings (dsp-DIF,
1.6°; dsp-DIT, 1.2°; dsp-DIP-Ph, 2.8°). As a result, highly
symmetrical structures of these compounds afforded simple
NMR spectra. Furthermore, according to the packing structure,
the intermolecular π-π stackings are completely suppressed
by the orthogonally arranged spirofluorene structures.15
The absorption and emission spectra of dispiro com-
pounds dsp-DIF, dsp-DIT, and dsp-DIP-Ph were measured
(14) Curtis, M. D.; Cao, J.; Kampf, J. W. J. Am. Chem. Soc. 2004, 126,
(13) Saragi, T. P. I.; Spehr, T.; Siebert, A.; Fuhrmann-Lieker, T.; Salbeck,
J. Chem. Rev. 2007, 107, 1011.
4318.
(15) See the Supporting Information.
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SCHEME 5. Synthesis of dsp-DIP-Ph
In addition, dsp-DIT showed higher photoluminescence
quantum yield in the solid state compared to DIT because
of the suppression of intermolecular π-π stackings by
SCHEME 6. Transformation of 10 to 6
in THF (Figure 3), and the results are summarized in Table 1.
These dispiro compounds exhibited a blue emission in THF
solution with moderate quantum efficiency. In the absorp-
tion spectra, the absorption maxima of dsp-DIF were obser-
ved at 348 and 367 nm, while those of dsp-DIT and dsp-DIP-
Ph were slightly red-shifted from 6 to 10 nm. The Stokes
shifts were very small (6-18 nm) because of their extremely
rigid structure. It is conceivable that both absorption and
emission maxima of dsp-FIP-Ph were observed more red-
shifted because the π-system is slightly extended due to
delocalization of the π-electron over the phenyl group on
the nitrogen atom.
We next compared the photophysical properties of dsp-
DIT with those of reference compounds 2,5-diphenylthio-
phene (DPT) and DIT (Figure 3, Table 1). The absorption
and emission spectra of DIT were largely red-shifted, com-
pared with those of DPT because of the linking between a
thiophene ring and two phenyl groups with methylene
chains. The photoluminescence quantum yield of DIT was
also increased because of the higher rigidity of its structure.
Furthermore, by incorporation of spirofluorene moieties,
greater bathochromic shifts were observed in the absorption
and emission spectra of dsp-DIT, as well as an increase in
quantum yield. This suggests that spirofluorene moieties
increase the rigidity of the π-backbone and suppress the
photo/thermal oxidation of methylene carbon,16 thereby ex-
tending the π-conjugation and increasing the quantum yield.
FIGURE 2. X-ray crystal structures of (a) dsp-DIF, (b) dsp-DIT,
and (c) dsp-DIP-Ph: (left) top view and (right) side view. All solvent
molecules and hydrogen atoms are omitted for clarity.
(16) Wiesenhofer, H.; Beljonne, D.; Scholes, G. D.; Hennebicq, E.;
ꢀ
Bredas, J.-L.; Zojer, E. Adv. Funct. Mater. 2005, 15, 155.
J. Org. Chem. Vol. 75, No. 3, 2010 909

Kowada et al.
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FIGURE 3. Absorption spectra (left) and the emission spectra (right) of dsp compounds and related compounds in THF.
TABLE 1. Optical Properties of dsp Compounds and Related Compounds in THF
aAbsolute quantumyield determined by a calibrated integrating sphere system. bλex 350 nm. Relative quantumyield calculated using quinine sulfate in
0.1 M aq H2SO4 as a standard.
TABLE 2. Optical Properties of dsp Compounds and DIT in the Solid
State
a
compound
λex [nm]
λem [nm]
Φsolid
dsp-DIF
dsp-DIT
dsp-DIP-Ph
DIT
348
356
358
342
401, 422
492, 522
467
0.089
0.099
0.040
0.017
409
aAbsolute quantum yield determined by a calibrated integrating
sphere system.
FIGURE 4. Molecular orbital plots for dsp-DIT.
spirofluorene moieties (Table 2). The bathochromic shifts of
absorption and emission maxima of dsp-DIT relative to
those of DIT seem to be also attributed to spiroconjugation17
between two fluorene moieties and the diindenothiophene
skeleton. We then performed a DFT calculation (B3LYP/
6-31G(d)) to gain insight into spiroconjugation for dsp-DIT.
Indeed, the conjugation between two fluorene moieties and
the diindenothiophene skeleton was confirmed to exist in the
HOMO level (Figure 4).
The oxidation potentials of dsp compounds and related
compounds were measured in CH2Cl2 (Table 3). The first
oxidation potentials of dsp compounds were dependent on the
nature of the central heteroarene. Because N-phenylpyrrole
TABLE 3. Oxidation Potentials of dsp Compounds and Related Com-
pounds in CH2Cl2
compound
E1/2 ox [V]b
dsp-DIF
dsp-DIT
dsp-DIP-Ph
DPT
0.504, 1.132
0.452, 0.596, 0.920
0.272, 1.100
0.616, 0.932
0.616
DIT
aAbsolute quantum yield determined by a calibrated integrating
sphere system. bIn CH2Cl2 containing 0.10 M Bu4NPF6 vs Fc/Fcþ at
100 mV s-1
.
can stabilize the generated radical cation, dsp-DIP-Ph shows
the lowest oxidation potential. Thiophene compounds DPT
and DIT show their first oxidation potentials with the same
value. It is suggested that bridging between the thiophene ring
€
(17) For a recent review, see: Geuenich, D.; Hess, K.; Kohler, F.; Herges,
R. Chem. Rev. 2005, 105, 3758.
910 J. Org. Chem. Vol. 75, No. 3, 2010

Kowada et al.
JOCArticle
and two phenyl rings scarcely affects the electronic nature of
these compounds. Nevertheless, the first oxidation potential of
dsp-DIT is much lower than those of DPT and DIT. Itmight be
due to increase of the HOMO level of dsp-DIT by spiroconju-
gation.
The solvents were removed under reduced pressure, and the residue
was purified with column chromatography on SiO2 (hexane) to give
2 (2.36 g, 96%) as a white solid: mp 129.0-129.8 °C; IR (KBr) 550,
622, 751, 841, 889, 936, 1019, 1066, 1252, 1448, 2947, 3062 cm-1
;
1H NMR (300 MHz, CDCl3) δ=-0.37 (s, 9H), 7.11 (m, 3H), 7.16
(dd, J=7.3, 7.7 Hz, 2H), 7.34-7.46 (m, 4H), 7.64 (d, J=7.3 Hz,
2H), 8.45 (br s, 1H); 13C NMR (75.5 MHz, CDCl3) δ=1.0, 84.8,
119.8, 120.5, 125.0, 126.8, 127.9, 128.7, 129.0, 129.6, 134.3, 142.0,
142.7, 148.2. Anal. Calcd for C22H21BrOSi: C, 64.54; H, 5.17.
Found: C, 64.33; H, 5.16.
In conclusion, we have synthesized new types of ladder
dispiro compounds dsp-FIF, dsp-FIT, and dsp-FIP-Ph. In
the emission spectra, the dispiro compounds showed blue
emission with moderate quantum yields, and it was clarified
that two spirofluorene moieties could increase the rigidity of
the π-frameworks, resulting in an elongation of π-conjuga-
tion and higher photoluminescence quantum yields.
Furthermore, a DFT calculation supported the suggestion
that the bathochromic shifts of the absorption and emission
maxima of dsp-DIT relative to those of DIT were attributed
to spiroconjugation between two fluorene moieties and the
diindenothiophene skeleton. The structures of all dispiro
compounds have been confirmed by X-ray crystallography,
and their two fluorene moieties were fixed closely at the same
side. In particular, for dsp-DIT, two fluorene rings were
placed in a parallel fashion and completely overlapped,
and their distances from each other were suitable for π-π
stacking.
2,5-Bis(2-(9-(trimethylsilyloxy)-9H-fluoren-9-yl)phenyl)furan
(3). A flame-dried flask was charged with 2 (15.7 g, 38.3 mmol),
2,5-bis(trimethylstannyl)furan19 (7.52 g, 19.1 mmol), Pd(PPh3)4
(2.19 g, 1.89 mmol), and dry 1,4-dioxane (60 mL) under nitrogen
atmosphere. The solution was stirred at 100 °C for 12 h. The
reaction mixture was cooled to room temperature and filtered
through a short Celite pad. After an addition of water (30 mL),
the filtrate was extracted with EtOAc (3ꢀ20 mL). The organic
layers were combined, washed with brine (2ꢀ20 mL), and dried
over MgSO4. The solvents were removed under reduced pres-
sure to give a yellowish brown solid. The crude product was
purified by washing with hexane to give 3 (10.9 g, 85%) as a
white solid: mp 232.2-233.0 °C; IR (KBr) 731, 751, 842, 890,
1
934, 1056, 1251, 1449, 2954, 3061 cm-1; H NMR (300 MHz,
CDCl3) δ=-0.49 (s, 18H), 4.16 (br s, 2H), 6.49 (d, J=7.3 Hz,
2H), 6.99 (d, J=7.3 Hz, 4H), 7.09 (dd, J=7.0, 7.3 Hz, 4H), 7.17
(dd, J=7.0, 7.7 Hz, 4H), 7.23 (m, 6H), 7.43 (dd, J=7.7, 7.7 Hz,
2H), 8.26 (br s, 2H); 13C NMR (75.5 MHz, CDCl3) δ=0.9, 84.2,
109.1, 119.7, 125.2, 126.2, 127.4, 127.6, 128.0, 128.4, 129.6,
132.2, 140.6, 142.9, 149.8, 150.7. Anal. Calcd for C48H44O3Si2:
C, 79.52; H, 6.12. Found: C, 79.48; H, 6.11.
Experimental Section
General. Unless otherwise specified, all reagents were pur-
chased from a chemical supplier and used without further
purification. All solvents were dried by the standard method.
Melting points are uncorrected. Degassed spectral grade sol-
vents were used for the UV-visible absorption and emis-
sion spectra measurements. Absolute fluorescence quantum
yields were determined by the calibrated integrating sphere
system.
2,5-Bis(2-(9-hydroxy-9-fluorenyl)phenyl)furan (4). To a solu-
tion of 3 (10.9 g, 15.3 mmol) in MeOH (200 mL) was added
K2CO3 (10.3 g, 74.5 mmol), and the solution was stirred at 50 °C
for 48 h. After cooling to ambient temperature, the reaction
mixture was filtered through a short Celite pad, and MeOH was
removed under reduced pressure. After an addition of water
(80 mL), the residue was extracted with Et2O (3 ꢀ 30 mL). The
organic layers were combined, washed with brine (3 ꢀ 20 mL),
and dried over MgSO4. The solvents were removed under
reduced pressure, and the residue was purified by washing with
Et2O-hexane (1:10) to give 4 (6.74 g, 76%) as a white solid: mp
230.1-231.0 °C; IR (KBr) 637, 732, 769, 914, 1013, 1117, 1165,
1448, 3060, 3438, 3532 cm-1; 1H NMR (300 MHz, CDCl3) δ=
2.44 (s, 2H), 4.78 (br s, 2H), 6.79 (d, J=7.3 Hz, 2H), 7.06-7.14
(m, 8H), 7.19 (dd, J=7.3, 7.7 Hz, 4H), 7.26 (dd, J=7.3, 7.3 Hz,
2H), 7.34-7.43 (m, 6H), 7.99 (br s, 2H); 13C NMR (75.5 MHz,
CDCl3) δ=83.0, 109.4, 120.0, 124.2, 126.7, 127.3, 128.0, 128.4,
128.6, 129.6, 132.3, 139.8, 141.1, 150.8 (one peak cannot be
discriminated due to overlap with another peak). Anal. Calcd
for C42H28O3: C, 86.87; H, 4.86. Found: C, 86.57; H, 4.92.
Dispiro[9H-fluorene-9,50(60H)-diindeno[1,2-b:20,10-d]furan-60,900-
[9H]fluorene] (dsp-DIF). To the solution of 4 (116 mg, 0.199 mmol)
in CH2Cl2 (15 mL) was added MeSO3H (114 mg, 1.16 mmol) in
CH2Cl2 (5 mL) at -78 °C. After stirring for 1 h, the reaction
mixture was quenched with water (15 mL) and extracted with
CH2Cl2 (2ꢀ5 mL). The organic layers were combined, washed with
brine (2 ꢀ 10 mL), and dried over MgSO4. The solvents were
removed under reduced pressure to give a yellow solid. The crude
product was recrystallized from toluene-hexane (4:1) to give dsp-
DIF (51.5 mg, 47%) as a white solid: mp 284.4-285.1 °C; IR (KBr)
735, 759, 1446 cm-1; 1H NMR (300 MHz, CDCl3) δ=6.46 (d, J=
7.7 Hz, 4H), 6.51 (d, J=7.7 Hz, 2H), 6.71 (dd, J=7.3, 7.7 Hz, 4H),
6.88 (dd, J = 7.3, 7.7 Hz, 2H), 7.00 (dd, J = 7.3, 7.7 Hz, 4H),
7.26 (dd, J = 7.3, 7.7 Hz, 2H), 7.31 (d, J = 7.7 Hz, 4H), 7.53 (d,
9-(2-Bromophenyl)-9H-fluoren-9-ol (1).18 To the solution of
1,2-dibromobenzene (2.83 g, 12.0 mmol) in dry THF (20 mL)
and dry Et2O (20 mL) was added dropwise 1.55 M hexane
solution of n-BuLi (7.74 mL, 12.0 mmol) at -120 °C. After
stirring for 1 h, 9-fluorenone (1.95 g, 10.8 mmol) in dry THF/
Et2O (15 mL, 1:2) was added over 35 min and stirred at -120 °C
for 3 h. The reaction mixture was quenched with saturated
aqueous solution of NH4Cl (30 mL) and extracted with Et2O
(3 ꢀ 10 mL). The organic layers were combined, washed with
brine (2 ꢀ 10 mL), and dried over MgSO4. The solvents were
removed under reduced pressure to give an orange oil. The crude
product was purified with column chromatography on SiO2
(EtOAc-hexane, 1:20) to give 1 (3.41 g, 94%) as a white solid:
mp 145.2-146.0 °C; IR (KBr) 767, 920, 1005, 1157, 1333, 1448,
1604, 3063, 3571 cm-1; 1H NMR (300 MHz, CDCl3) δ = 2.39
(br s, 1H), 7.13-7.25 (m, 5H), 7.36-7.47 (m, 4H), 7.67 (d, J =
7.7 Hz, 2H), 8.44 (br s, 1H); 13C NMR (75.5 MHz, CDCl3) δ=
83.0, 120.2, 120.9, 123.9, 127.0, 128.3, 129.0, 129.1, 129.2, 134.3,
140.8, 141.3, 148.6.
9-(2-Bromophenyl)-9-(trimethylsilyloxy)-9H-fluorene (2). To
the solution of 1 (2.03 g, 6.02 mmol), Et3N (4.20 mL, 30.1
mmol), and DMAP (73.5 mg, 0.602 mmol) in CH2Cl2 (10 mL)
was added chlorotrimethylsilane (1.08 mL, 8.55 mmol), and the
solution was stirred at room temperature for 13 h under nitrogen
atmosphere. The reaction mixture was quenched with water (15 mL)
and extracted with CH2Cl2 (3 ꢀ 10 mL). The organic layers were
combined, washed with brine (2ꢀ10 mL), and dried over MgSO4.
(18) Arts, H. J.; Kranenburg, M.; Meijers, R. H. A. M.; Ijpeij, E. G.;
Gruter, G. J. M.; Beijer, F. H. Indenyl compounds for the polymerisation of
olefins. Eur. Pat. Appl. 1059300, Nov 6, 1999; Chem Abstr. 2000, 134, 42577.
(19) Seitz, D. E.; Lee, S.-H.; Hanson, R. N.; Bottaro, J. C. Synth.
Commun. 1983, 13, 121.
J. Org. Chem. Vol. 75, No. 3, 2010 911

Kowada et al.
JOCArticle
J = 7.7 Hz, 2H); 13C NMR (75.5 MHz, CDCl3) δ = 58.4, 116.2,
119.4, 122.9, 124.2, 125.4, 127.1, 127.4, 127.6, 132.3, 134.2, 141.1,
144.1, 150.4, 162.4. Anal. Calcd for C42H24O: C, 92.62; H, 4.44.
Found: C, 92.67; H, 4.61.
reaction mixture was stirred at room temperature for 3 h. The
reaction mixture was quenched with 10% aqueous solution of
NaHSO3 (10 mL) and extracted with EtOAc (3 ꢀ 10 mL). The
organic layers were combined, washed with brine (2ꢀ10 mL), and
dried over MgSO4. The solvents were removed under reduced
pressure, and the residue was partially purified with column chro-
matography on SiO2 (EtOAc-hexane, 1:10) to give 7 (266 mg) as a
white solid.
A flame-dried Schlenk flask was charged with 7 (266 mg,
1.44 mmol), CuI (3.9 mg, 0.020 mmol), Pd(PPh3)4 (7.9 mg, 6.8ꢀ
10-3 mmol), i-PrNH2 (1.5 mL), dry THF (6 mL), and trimethyl-
silylacetylene (0.115 mL, 0.81 mmol) under nitrogen atmo-
sphere. The solution was stirred at room temperature for 16 h.
The reaction mixture was cooled to room temperature and
filtered through a short Celite pad. After an addition of water
(10 mL), the filtrate was extracted with EtOAc (3ꢀ5 mL). The
organic layers were combined, washed with brine (2 ꢀ 10 mL),
and dried over MgSO4. The solvents were removed under
reduced pressure, and the residue was purified with column chro-
matography on SiO2 (EtOAc-hexane, 1:40) to give 8(188 mg, 71%
yield based on 5) as a pale yellow solid.
9-(2-Bromophenyl)-9-(methoxymethoxy)-9H-fluorene (5). A
flame-dried flask was charged with NaH (60% dispersion in oil,
73.2 mg, 1.8 mmol) and dry THF (5 mL) under nitrogen atmo-
sphere. A solution of 1 (460 mg, 1.37 mmol) in dry THF (3 mL) was
added to the suspension, and the mixture was stirred at 0 °C for
2 h. To the reaction mixture was added ClCH2OCH3 (0.430 mL,
5.70 mmol), and the reaction mixture was stirred at 0 °C for 3 h.
After an addition of water (10 mL), the residue was extracted with
Et2O (3ꢀ10 mL). The organic layers were combined, washed with
brine (3 ꢀ 10 mL), and dried over MgSO4. The solvents were
removed under reduced pressure, and the residue was purified with
column chromatography on SiO2 (EtOAc-hexane, 1:20) to give 5
(412 mg, 79%) as a white solid: mp 73.5-74.4 °C; IR (KBr) 733,
763, 916, 1026, 1039, 1086, 1148, 1269, 1461, 2927 cm-1; 1H NMR
(300 MHz, CDCl3) δ = 3.16 (s, 3H), 4.29 (s, 2H), 7.10-7.15 (m,
3H), 7.20-7.25 (m, 2H), 7.37-7.47 (m, 4H), 7.66 (d, J= 7.3 Hz,
2H), 8.48 (br s, 1H); 13C NMR (75.5 MHz, CDCl3) δ=55.9, 86.3,
91.5, 119.8, 120.8, 125.0, 126.9, 128.0, 128.8, 129.3, 129.4, 134.7,
141.0, 142.8, 145.3. Anal. Calcd for C21H17BrO2: C, 66.16; H, 4.49.
Found: C, 66.22; H, 4.55.
2,5-Bis(2-(9-(methoxymethoxy)-9H-fluoren-9-yl)phenyl)thio-
phene (6). A flame-dried Schlenk flask was charged with 5 (723 mg,
1.90 mmol), 2,5-bis(trimethylstannyl)thiophene19 (369 mg, 0.901
mmol), Pd(PPh3)4 (53.3 mg, 0.046 mmol), and dry toluene (8 mL)
under nitrogen atmosphere. The solution was stirred at 100 °C for
87 h. The reaction mixture was cooled to room temperature and
filtered through a short Celite pad. The solvents were removed
under reduced pressure, and the residue was purified with column
chromatography on SiO2 (EtOAc-hexane, 1:12) to give 6 (202 mg,
33%) as a yellow solid: mp 210.9-211.8 °C; IR (KBr) 736, 756,
1036, 1152, 1211, 1449, 2924 cm-1; 1H NMR (300 MHz, CDCl3)
δ=3.19 (s, 6H), 4.13 (s, 4H), 4.50 (s, 2H), 6.86 (d, J=7.3 Hz, 2H),
7.03-7.10 (m, 8H), 7.15-7.22 (m, 8H), 7.28 (dd, J= 7.3, 7.7 Hz,
2H), 7.49 (dd, J= 7.3, 7.7 Hz, 2H), 8.43 (d, J= 8.0 Hz, 2H); 13C
NMR (75.5 MHz, CDCl3) δ=55.8, 85.8, 91.3, 119.6, 125.0, 125.2,
126.2, 126.9, 127.7, 127.8, 128.7, 132.8, 132.8, 140.1, 141.4, 141.8,
147.3. Anal. Calcd for C46H36O4S: C, 80.67; H, 5.30. Found: C,
80.40; H, 5.59.
9-(2-Iodophenyl)-9-(methoxymethoxy)-9H-fluorene (7): mp
73.6-74.6 °C; IR (KBr) 732, 752, 762, 915, 1029, 1086, 1149,
1447, 2927 cm-1; 1H NMR (300 MHz, CDCl3) δ=3.14 (s, 3H),
4.29 (s, 2H), 6.93 (dd, J=7.7, 7.7 Hz, 1H), 7.10 (d, J=7.3 Hz,
2H), 7.23 (dd, J=7.3, 7.7 Hz, 2H), 7.40 (dd, J=7.7, 7.7 Hz, 2H),
7.51 (dd, J=7.3, 7.3 Hz, 1H), 7.66 (d, J=7.3 Hz, 2H), 7.76 (d,
J=7.3 Hz, 1H), 8.52 (d, J=7.7 Hz, 1H); 13C NMR (75.5 MHz,
CDCl3) δ=55.8, 87.3, 91.6, 119.8, 125.48, 125.45, 127.7, 128.1,
129.0, 129.2, 129.5, 142.2, 143.2, 143.9, 144.8. Anal. Calcd for
C21H17IO2: C, 58.89; H, 4.00. Found: C, 59.15; H, 4.00.
8: mp 47.8-48.8 °C; IR (neat) 751, 766, 838, 859, 1026, 1147,
1246, 1448, 1473, 2155, 2953 cm-1; 1H NMR (300 MHz, CDCl3)
δ=-0.04 (s, 9H), 3.15 (s, 3H), 4.33 (s, 2H), 7.17-7.26 (m, 5H),
7.34-7.39 (m, 4H), 7.62 (d, J=7.3 Hz, 2H), 8.16 (br s, 1H); 13
C
NMR (75.5 MHz, CDCl3) δ=-0.3, 55.8, 86.5, 91.6, 99.1, 102.6,
119.7, 120.5, 125.3, 126.6, 127.0, 127.8, 128.2, 129.0, 135.8,
142.1, 143.3, 146.4. Anal. Calcd for C26H26O2Si: C, 78.35; H,
6.58. Found: C, 78.09; H, 6.50.
9-(2-Ethynylphenyl)-9-(methoxymethoxy)-9H-fluorene (9).
To a solution of 8 (854 mg, 2.14 mmol) in MeOH (20 mL) and
THF (5 mL) was added K2CO3 (443 mg, 3.20 mmol), and the
solution was stirred at 50 °C for 12 h. After cooling to ambient
temperature, the reaction mixture was quenched with water (10 mL)
and extracted with EtOAc (3 ꢀ 5 mL). The organic layers were
combined, washed with brine (2ꢀ10 mL), and dried over MgSO4.
The solvents were removed under reduced pressure, and the residue
was purified with column chromatography on SiO2 (EtOAc-
hexane, 1:25) to give 9 (682 mg, 98%) as a pale yellow oil: IR
Dispiro[9H-fluorene-9,50(60H)-diindeno[1,2-b:20,10-d]thiophene-
60,900-[9H]fluorene] (dsp-DIT). To the solution of 6 (62.2 mg, 0.091
mmol) in AcOH (5.0 mL) was added 10% aqueous solution of HCl
(0.10 mL), and the solution was stirred at room temperature for 1 h.
The reaction mixture was poured into saturated aqueous solution
of NaHCO3 (20 mL) and extracted with EtOAc (3 ꢀ 5 mL). The
organic layers were combined, washed with saturated aqueous
solution of NaHCO3 (3 ꢀ 10 mL), and dried over MgSO4. The
solvents were removed under reduced pressure to give a yellow
solid. The crude product was recrystallized from toluene-hexane
(4:1) to give dsp-DIT (23.6 mg, 46%) as a yellow solid: mp
(neat) 641, 750, 922, 1026, 1152, 1449, 1474, 2930, 3062, 3293 cm-1
;
1H NMR (300 MHz, CDCl3) δ= 2.60 (s, 1H), 3.20, (s, 3H), 4.37
(s, 2H), 7.18-7.29 (m, 5H), 7.33-7.41 (m, 4H), 7.61 (d, J=7.0 Hz,
2H), 8.12 (br s, 1H); 13C NMR (75.5 MHz, CDCl3) δ=55.9, 80.8,
81.8, 86.7, 91.8, 119.4, 119.5, 125.4, 126.7, 127.1, 127.8, 128.5, 129.2,
135.3, 142.4, 144.3, 146.3. Anal. Calcd for C23H18O2: C, 84.64; H,
5.56. Found: C, 84.66; H, 5.57.
276.8-277.5 °C; IR (KBr) 740, 753, 1283, 1447, 1601, 2920 cm-1
;
1H NMR (300 MHz, CDCl3) δ = 6.30 (d, J = 7.3 Hz, 2H), 6.34
(d, J= 7.7 Hz, 4H), 6.65 (dd, J= 7.3, 7.3 Hz, 4H), 6.83 (dd, J=
6.2, 7.7 Hz, 2H), 7.00 (dd, J= 7.3, 7.7 Hz, 4H), 7.20 (dd, J=7.3,
7.7 Hz, 2H), 7.25 (d, J = 7.3 Hz, 4H), 7.49 (d, J = 7.7 Hz, 2H);
13C NMR (75.5 MHz, CDCl3) δ=62.9, 118.2, 119.7, 123.1, 123.2,
125.8, 127.1, 127.2, 127.4, 138.6, 141.1, 144.2, 145.8, 146.4, 151.8;
HRMS (FAB) calcd for C42H25S (M þ Hþ) 561.1677, found
561.1673.
1,4-Bis(2-(9-(methoxymethoxy)-9H-fluoren-9-yl)phenyl)buta-
1,3-diyne (10). To a solution of 9 (1.04 g, 3.20 mmol) and Et3N
(0.900 mL, 6.46 mmol) in 1,4-dioxane (30 mL) was added
Cu(OAc)2 (291 mg, 1.60 mmol), and the solution was stirred
at 100 °C for 13 h. The reaction mixture was cooled down to
ambient temperature and filtered through a short Celite pad.
After an addition of water (30 mL), the residue was extracted
with EtOAc (3 ꢀ 10 mL). The organic layers were combined,
washed with brine (3 ꢀ 20 mL), and dried over MgSO4. The
solvents were removed under reduced pressure, and the residue
was purified with column chromatography on SiO2 (EtOAc-
hexane, 1:8) to give 10 (979 mg, 94%) as a white solid: mp
9-(Methoxymethoxy)-9-(2-((trimethylsilyl)ethynyl)phenyl)-9H-
fluorene (8). A flame-dried flask was charged with 5 (254 mg, 0.666
mmol) and dry THF (7 mL) under nitrogen atmosphere. To the
solution was added 1.55 M hexane solution of n-BuLi (0.454 mL,
0.704 mmol) at -78 °C. After stirring 1 h, a solution of I2 (170 mg,
0.671 mmol) in dry THF (3 mL) was added to the solution, and the
912 J. Org. Chem. Vol. 75, No. 3, 2010

Kowada et al.
JOCArticle
172.0-172.7 °C; IR (KBr) 751, 786, 907, 1039, 1093, 1142, 1232,
1450, 2873 cm-1; 1H NMR (300 MHz, CDCl3) δ=3.16 (s, 6H),
4.35, (s, 4H), 7.19-7.38 (m, 18H), 7.58 (d, J=7.0 Hz, 4H), 7.87
(br s, 2H); 13C NMR (75.5 MHz, CDCl3) δ = 56.0, 78.7, 81.1,
87.0, 92.1, 119.7, 119.8, 125.1, 126.7, 127.1, 127.8, 128.6, 129.3,
135.4, 141.8, 145.1, 146.0. Anal. Calcd for C46H34O4: C, 84.90;
H, 5.27. Found: C, 84.81; H, 5.15.
11-Phenyldispiro[9H-fluorene-9,50(60H)-diindeno[1,2-b:20,10-d]
pyrrole-60,900-[9H]fluorene] (dsp-DIP-Ph). A flame-dried Schlenk
flask was charged with 10 (194 mg, 0.299 mmol), CuCl (7.5 mg,
0.076 mmol), and PhNH2 (1.2 mL) under nitrogen atmosphere.
The solution was stirred at 150 °C for 44 h. The reaction mixture
was cooled to room temperature and filtered through a short Celite
pad. After an addition of EtOAc (10 mL), the filtrate was washed
with 10% aqueous solution of AcOH (5 ꢀ 10 mL), saturated
aqueous solution of NaHCO3 (3 ꢀ 10 mL), and brine (10 mL)
and dried over MgSO4. The solvents were removed under reduced
pressure, and the residue was partially purified with column
chromatography on SiO2 (EtOAc-hexane, 1:15) to give crude
product (63.1 mg) as a brown solid.
2923 cm-1; 1H NMR (300 MHz, CDCl3) δ=6.40 (d, J=7.3 Hz,
2H), 6.51 (d, J=7.7 Hz, 4H), 6.67-6.75 (m, 6H), 6.96-7.05 (m,
8H), 7.29 (d, J=7.3 Hz, 4H), 7.59 (dd, J=7.3, 7.7 Hz, 1H), 7.71
(dd, J = 7.3, 7.7 Hz, 2H), 7.93 (d, J = 7.7 Hz, 2H); 13C NMR
(75.5 MHz, CDCl3) δ = 59.3, 116.4, 119.3, 123.1, 124.0, 124.3,
126.2, 126.87, 126.94, 127.9, 129.5, 130.9, 135.9, 138.5, 141.0,
141.7, 145.8, 152.0 (one peak cannot be discriminated due to
overlap with another peak); HRMS (FAB) calcd for C48H30N
(M þ Hþ) 620.2378, found 620.2362.
Synthesis of 6 from Diyne 10. A flame-dried Schlenk flask was
charged with 10 (195 mg, 0.299 mmol), Na2S 9H2O (361 mg,
3
1.50 mmol), and dry DMF (5 mL) under nitrogen atmosphere.
The solution was stirred at 150 °C for 23 h. After cooling to
ambient temperature, water (10 mL) was added to the reaction
mixture. The residue was extracted with EtOAc (3ꢀ5 mL). The
organic layers were combined, washed with brine (3 ꢀ 10 mL),
and dried over MgSO4. The solvents were removed under
reduced pressure, and the residue was purified with column
chromatography on SiO2 (EtOAc-hexane, 1:10) to give 6(142mg,
69%) as a yellow solid.
To the solution of the crude product (63.1 mg) in AcOH
(2 mL) and toluene (2 mL) was added 35% aqueous solution of
HCl (0.050 mL), and the solution was stirred at room tempera-
ture for 3 h. The reaction mixture was poured into saturated
aqueous solution of NaHCO3 (15 mL) and extracted with
EtOAc (3 ꢀ 5 mL). The organic layers were combined, washed
with saturated aqueous solution of NaHCO3 (3 ꢀ 10 mL), and
dried over MgSO4. The solvents were removed under reduced
pressure, and the residue was purified with column chromato-
graphy on SiO2 (EtOAc-hexane, 1:20) to give dsp-DIP-Ph
(40.0 mg, 22% yield based on 10) as a pale yellow solid: mp
284.4-285.5 °C; IR (KBr) 727, 737, 1445, 1473, 1508, 1602,
Acknowledgment. T.K. gratefully acknowledges the finan-
cial support by the Global COE Program “International Center
for Integrated Research and Advanced Education in Materials
Science” (No. B-09) of MEXT.
1
Supporting Information Available: Copies of H and 13C
NMR spectra for all new compounds, X-ray data of dsp-DIF,
dsp-DIT, and dsp-DIP-Ph, and DFT calculation data of dsp-
DIT. This material is available free of charge via the Internet at
http://pubs.acs.org.
J. Org. Chem. Vol. 75, No. 3, 2010 913