Synthesis and photoluminescence study of benz[f]indene derivatives

Article abstract of DOI:10.1016/j.tetlet.2005.04.128

The synthesis and optical properties of a series of benz[f]indenes as new building blocks for electronic and optoelectronic materials are described.

Full text of DOI:10.1016/j.tetlet.2005.04.128

Tetrahedron
Letters
Tetrahedron Letters 46 (2005) 4627–4631
Synthesis and photoluminescence study of benz[f]indene derivatives
Do Han Kim,a Jung A Lee,a Seung Uk Son,a Young Keun Chunga,* and Cheol Ho Choib
aDepartment of Chemistry, College of Natural Sciences, Seoul National University, Seoul 151-747, Republic of Korea
bDepartment of Chemistry, Kyungpook National University, Daegu 702-701, Republic of Korea
Received 18 August2004; revised 27 April 2005; accepted 28 April 2005
Available online 23 May 2005
Abstract—The synthesis and optical properties of a series of benz[f]indenes as new building blocks for electronic and optoelectronic
materials are described.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Anthracene derivatives are key compounds in the design
1
benz[f]indenes and a time-dependent DFT calculation
of their excited states.
of luminescentmaetrials.
For example, 9,10-diphenyl-
anthracene (DPA) has been widely used in chemilumin-
escene2 and many functionalized anthracenes have been
reported to yield efficient blue organic light-emitting
diodes.3 Moreover, light-emitting polymers containing
DPA have been widely studied.4
Scheme 1 shows the synthesis of benz[f]indenes. Unsub-
stituted benz[f]indene (1) was prepared by the procedure
reported by Becker and McLaughlin.9 Compounds 2–6
were synthesized by a method previously reported by
the authors.7 As described in Scheme 1, compound b,
synthesized by an intermolecular Pauson–Khand reac-
tion of substituted oxabenzonorbornadienes and alky-
nes, was transformed into c by dehydration under an
acidic condition. Treatment of c with a hydrogen bal-
loon in the presence of Pd/C, followed by reduction by
LAH and dehydration (refluxing with anhydrous
MgSO4 in hexane or toluene) afforded 2–6 in high yields.
In the dehydration step, compounds 3e, 4e, and 5e were
refluxed with anhydrous MgSO4 in hexane because they
have a good solubility in hexane at high temperature.
However, compounds 2e and 6e have a poor solubility
in hexane. Thus, they were refluxed with anhydrous
MgSO4 in toluene. After dehydration, two isomeric
compounds were obtained for 5e due to a double bond
migration. However, a chromatographic separation
gave a pure 5. All compounds except 2 and 6 were quite
soluble in dichloromethane and THF. To confirm the
structure of this family of compounds, a single-crystal
X-ray analysis of 4 (formed in Et2O by slow cooling)
was performed (Fig. 1).10
Fluorene has aromatic benzene rings fused to both
cyclopentadiene double bonds. Recently, polyfluorenes
(PF) have especially attracted much attention as good
candidates for light-emitting diode applications because
of their high solid-state photoluminescence (PL) quan-
tum efficiencies, excellent solubility, and film-forming
capability, and the ease in controlling their properties
via facile substitution in the 9-position.5 Moreover, the
liquid-crystalline order of some PFs has opened the
way to fabricate blue polarized electroluminescent
devices.6
In contrast, benz[f]indenes, the isomer of fluorenes, hav-
ing quite a similar structure to anthracenes, have hith-
erto never attracted attention in relation to the study
of luminescent materials, presumably due to the lack
of available synthetic methods. However, we recently
developed a synthetic method for benz[f]indenes using
the Diels–Alder reaction and Pauson–Khand reaction.7
Interestingly, our methodology easily introduces substit-
uents to the 4,9-positions of benz[f]indenes. Here we re-
port the synthesis and optical properties of a series of
Figure 2 displays the UV–vis and photoluminescent
(PL) spectra of 1–6 in solution. In the cases of 2–4
and 6, t hekmax values were red-shifted compared to
those of 1 and 5 presumably due to the longer conjuga-
tion by the presence of phenyl group. The absorption
spectra of 2–4 and 6 display two groups of bands around
Keywords: Fluorescence; Photoluminescence; Benzindene.
*
Corresponding author. Tel.: +82 2 880 6662; fax: +82 2 889 0310;
e-mail: ykchung@plaza.snu.ac.kr
0040-4039/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2005.04.128

4628
D. H. Kim et al. / Tetrahedron Letters 46 (2005) 4627–4631
R
R
R
R
2
O
R
2
2
O
R
2
H
H
R
R
R
i
ii
3
3
3
O
R
R
O
R
R
1
+
R
R
R
3
3
3
R
1
R
1
2
2
2b: R = Ph, R1=R2 = R3 = H
2c - 6c
3b: R = Ph, R1 = H, R2 = Me, R3 = H
4b: R = Ph, R1 = H, R2 = Ph, R3 = H
5b: R = R1 = R2 = Me, R3 = H
iii
6b: R = Ph, R1 = H, R2 = Me, R3 = OMe
R
R
2
R
OH
2
O
R
2
R
R
R
iv
v
3
3
3
R
R
R
R
R
R
3
3
3
R
1
R
R
R
2
R
1
1
2
2
2 - 6
Scheme 1. Synthetic strategy for synthesis of benz[f]indenes.8
2e - 6e
2d - 6d
Figure 1. An ORTEP drawing of 4.
270–300 and 320–350 nm, butfor 1 and 5 one group of
band appears around 280–320 nm. The noticeable differ-
ence in the UV–vis spectra between these two groups of
compounds is presumably due to the presence of (a)
phenyl group(s) in the cyclopentadiene moiety. When
we calculated the kmax values for 1–6 and compared
them with observed values (Table 1), the overall trends
were consistent. B3LYP11 exchange-correlational func-
tions in combination with 6-31G(d) basis sets were
adopted to optimize geometries of 1–6. After that,
TD-DFT using the same theories were performed to cal-
culate excited states. All calculations were performed
using Gaussian98.12 The kmax values around 288–
344 nm for 1–6 suggested that benz[f]indenes are large
band-gap compounds.
Figure 2. UV–vis absorption (5 lM in dichloromethane) and PL
(0.5 lM in dichloromethane).
In solution, all these neutral compounds exhibit blue
emission (maximum of emission around 357–411 nm).
The kmax values were slightly dependent upon the

D. H. Kim et al. / Tetrahedron Letters 46 (2005) 4627–4631
4629
Table 1. Spectroscopic data for 1–6
Supplementary data
a
Compd Obsd kmaxabs
(nm)
Calcd kmaxabs kmaxem
(nm)
Urel
(%)
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.tetlet.
2005.04.128.
(nm)
1
2
3
4
5
6
278 288 300
278 289 323
285 298 327 341 298 331 349 406
295 301
341 352 357 374
5
26
38
78
5
274 292 326 369 387 407
288 299 342 283 305 336 407
301 313 304 346 356 371 388
271 301 344 357 258 306 312 344 357
References and notes
7
a Quantum yields were measured by dilute method14 using 2-(4-
biphenylyl)-5-phenyl-1,3,4-oxadiazole as standard.
1. (a) Rosenstock, H. B. J. Chim. Phys.-Chim. Biol. 1968, 48,
532; (b) Matsui, A.; Mizuno, K.; Kobayashi, M. J. Phys.
Colloq. 1985, 7, 19; (c) Kim, Y.-H.; Shin, D.-C.; Kim,
S.-H.; Ko, C.-H.; Yu, H.-S.; Chae, Y.-S.; Kwon, S.-K.
Adv. Mater. 2001, 13, 1690; (d) Gutierrez-Llorente, A.;
Perez-Casero, R.; Pajot, B.; Roussel, J.; Defourneau, R.
M.; Defourneau, D.; Fave, J. L.; Millon, E.; Perriere, J.
Appl. Phys. A: Mater. Sci. Process. 2003, 77, 785; (e)
Balaganesan, B.; Shen, W.-J.; Chen, C. H. Tetrahedron
Lett. 2003, 44, 5747; (f) Yamashita, T.; Uchida, T.;
Fukushima, T.; Teramae, N. J. Phys. Chem. B 2003, 107,
4786; (g) Geue, J. P.; Head, N. J.; Ward, A. D.; Lincoln, S.
F. J. Chem. Soc., Dalton Trans. 2003, 4, 521.
2. (a) Leszthelyi, C. P.; Bard, A. J. J. Electrochem. Soc. 1973,
120, 41; (b) Collinson, M. M.; Wightman, R. M. Anal.
Chem. 1993, 65, 2576; (c) Oyama, M.; Okazaki, S. Anal.
Chem. 1998, 70, 5079.
3. (a) Zhang, Z. L.; Jiang, X. Y.; Zhu, W. Q.; Zheng, X. Y.;
Wu, Y. Z.; Xu, S. H. Synth. Met. 2003, 137, 1141; (b)
Kondakov, D. Y.; Sandifer, J. R.; Tang, C. W.; Young, R.
H. J. Appl. Phys. 2003, 93, 1108; (c) Danel, K.; Huang,
T.-H.; Lin, J. T.; Tao, Y.-T.; Chuen, C.-H. Chem. Mater.
2002, 14, 3860; (d) Jiang, X.-Y.; Zhang, Z.-L.; Zheng,
X.-Y.; Wu, Y.-Z.; Xu, S.-H. Thin Solid Films 2001, 401,
251; (e) Kim, Y.; Oh, E.; Choi, D. W.; Lim, H.; Ha, C. S.
Nanotechnology 2004, 15, 149.
substituent. Compounds 2–4 and 6 having (a) phenyl
group(s) have a tendency to be slightly red-shifted and
have a similar longest wavelength. Compared with fluor-
ene (kmaxabs = 265 nm; kmaxem = 313 nm in cyclohex-
ane),13 kmax values of 1 were red-shifted even though
the difference of the solvents were considered. Unfortu-
nately, the quantum yields were poor except for 4 and
were highly dependent upon the substituents. In the
beginning, we envisioned that the formation of excimers
was one of the reasons of poor quantum yields. How-
ever, the study on the concentration and solvent effect
upon PL spectra showed that the formation of excimers
seemed to be difficult for 1–6. For example, the kmaxem
values of 4 in dichloromethane, chloroform, and ethyl
acetate were 407, 406, and 402 nm, respectively. Because
1–6 do not have any functional groups to react with sol-
vent molecules, we expect that there is no apparent dif-
ference depending upon the solvent. The Stokes shifts
were rather insensitive to the substituent. The poor
quantum yields might originate from other quenching
processes when radiated. Further study will provide
some clues for the rationalization of the poor quantum
4. (a) Boyd, T. J.; Geerts, Y.; Lee, J.-K.; Fogg, D. E.; Lavoic,
G. G.; Schrock, R. R.; Rubner, M. F. Macromolecules
1997, 30, 3553; (b) Boyd, T. J.; Schrock, R. R. Macro-
molecules 1999, 32, 6608.
yields. The highestquantum yield (0.78) observed for
4
was presumably due to the barricade of three phenyl
groups in the quenching processes. It has been well
established15 that the introduction of long or branched
side chains and copolymerization with suitable bulky
comonomers in fluorescentplanar molecules or poly-
mers suppresses the formation of p-aggregates.
5. (a) Grice, A. W.; Bradley, D. D. C.; Bernius, M. T.;
Inbasekaran, M.; Wu, W. W.; Woo, E. P. Appl. Phys. Lett.
1998, 73, 629; (b) Bernius, M. T.; Inbasekaran, M.;
OÕBrien, J.; Wu, W. S. Adv. Mater. 2000, 12, 1737; (c)
Neher, D. Macromol. Rapid Commun. 2001, 22, 1365; (d)
Scherf, U.; List, E. W. J. Adv. Mater. 2002, 14, 477; (e)
Leclerc, M. J. Polym. Sci. Part A: Polym. Chem. 2001, 39,
2867.
In summary, we have synthesized a series of benz[f]in-
dene derivatives by using our newly developed method
and studied their photophysical properties. All benz-
[f]indene derivatives investigated in this study have
exhibited fluorescence in the blue region (emission maxi-
mum around 350–410 nm) and have large band-gaps.
Depending upon the substituents, some of them showed
potential for application as optoelectronic materials. We
are currently exploring the synthesis of benz[f]indenes
having a polar functional group as well as improvement
of the photophysical properties in relation to the
substituent.
6. Grell, M.; Knoll, W.; Lupo, D.; Melsel, A.; Miteva, T.;
Neher, D.; Nothofer, H.-G.; Scherf, Y.; Yasuda, A. Adv.
Mater. 1999, 11, 671.
7. Kim, D. H.; Son, S. U.; Chung, Y. K. Org. Lett. 2003, 5,
3151.
8. General procedure for the Pauson–Khand reaction: To a
100 mL high-pressure reactor were added oxabenzonor-
bornadiene (0.52 g, 3.64 mmol), phenyl acetylene (0.20 mL,
1.82 mmol), 15 mL of CH2Cl2, and Co2(CO)8 (31 mg,
91 lmol). After the solution was flushed with CO gas for
several seconds, the reactor was pressurized with 30 atm of
CO. The reactor was heated at 130 ꢁC for 18 h. After the
reactor was cooled to rt and excess gas was relieved, the
solution was transferred into a flask and then evaporated to
dryness. The residue was chromatographed on a silica gel
column eluting with hexane and ethyl acetate (v/v, 8:1).
Acknowledgments
1
Compound 2b. Yield: 98%; H NMR (CDCl3): d 7.81 (d,
J = 2.9 Hz, 1H), 7.72 (d, J = 6.9 Hz, 2H), 7.41–7.33 (m,
5H), 7.21 (m, 2H), 5.52 (s, 1H), 5.23 (s, 1H), 3.10 (dd,
J = 5.2, 2.9 Hz, 1H), 2.73 (d, J = 5.2 Hz, 1H); 13C NMR
(CDCl3): d 205.4, 157.0, 147.7, 145.8, 131.6, 129.2, 128.8,
We thank the Ministry of Commerce, Industry, and
Energy of Korea. D.H.K. and J.A.L. are grateful for
a Brain Korea 21 fellowship.

4630
D. H. Kim et al. / Tetrahedron Letters 46 (2005) 4627–4631
1
127.7, 127.5, 126.3, 120.2, 119.9, 81.8, 80.4, 54.5, 48.5; IR
m(C@O) 1702 cmÀ1; HRMS for C19H14O2: calcd 274.0994,
obsd 274.0996.
Compound 5c. Yield: 92%; H NMR (CDCl3): d 7.99 (d,
J = 7.9 Hz, 1H), 7.90 (d, J = 8.2 Hz, 1H), 7.50 (d,
J = 8.4 Hz, 1H), 7.44 (d, J = 8.2 Hz, 1H), 2.85 (s, 3H),
2.61 (s, 3H), 2.34 (s, 3H), 1.79 (s, 3H); 13C NMR (CDCl3): d
197.8, 155.2, 137.3, 136.8, 134.2, 133.6, 127.9, 126.6, 126.2,
126.1, 125.3, 124.9, 16.17, 14.4, 11.8, 7.98; IR m(C@O)
1679 cmÀ1; HRMS for C17H16O: calcd 236.1201, obsd
236.1203.
1
Compound 3b. Yield: 92%; H NMR (CDCl3): d 7.76 (d,
J = 3.0 Hz, 1H), 7.72 (m, 2H), 7.40–6.90 (m, 7H), 3.06 (dd,
J = 5.1, 2.9 Hz, 1H), 2.57 (d, J = 5.1 Hz, 1H), 1.89 (s, 3H),
1.84 (s, 3H); 13C NMR (CDCl3): d 204.2, 155.5, 148.5,
147.6, 131.3, 128.7, 128.4, 127.3, 127.2, 126.9, 125.8, 118.2,
118.1, 85.8, 85.1, 57.5, 52.6, 14.7, 14.4; IR m(C@O)
1698 cmÀ1; HRMS for C21H18O2: calcd 302.1307, obsd
302.1306.
1
Compound 6c. Yield: 86%; H NMR (CDCl3): d 7.90 (s,
1H), 7.85 (d, J = 7.2 Hz, 2H), 7.42 (t, J = 7.7 Hz, 2H), 7.34
(t, J = 7.2 Hz, 1H), 7.32 (s, 1H), 7.16 (s, 1H), 4.04 (s, 3H),
4.02 (s, 3H), 2.85 (s, 3H), 2.52 (s, 3H); 13C NMR (CDCl3): d
197.6, 150.6, 149.1, 141.7, 137.9, 135.5, 134.6, 132.4, 131.3,
129.6, 128.6, 128.3, 127.4, 126.0, 125.4, 125.2, 106.6, 105.3,
56.0, 14.1, 12.3; IR m(C@O) 1685 cmÀ1; HRMS for
C23H20O3: calcd 344.1412, obsd 344.1417.
1
Compound 4b. Yield: 96%; H NMR (CDCl3): d 8.06 (d,
J = 7.1 Hz, 2H), 7.74 (d, J = 7.0 Hz, 2H), 7.51–6.86 (m,
15H), 4.19 (m, 1H), 3.86 (d, J = 5.9 Hz, 1H); 13C NMR
(CDCl3): d 203.3, 154.9, 145.4, 144.9, 143.7, 137.6, 130.9,
128.7, 128.4, 128.2, 128.1, 127.6, 127.5, 127.3, 127.1, 126.7,
126.3, 125.9, 120.9, 119.5, 90.4, 89.8, 58.6, 53.3; IR m(C@O)
1699 cmÀ1; HRMS for C31H22O2: calcd 426.1620, obsd
426.1622.
General procedure for the synthesis of benz[f]indanone: To
a 50 mL schlenk flask filled with nitrogen were added a
solution of 3c (0.30 g, 1.06 mmol) in 25 mL of THF and Pd/
C (0.30 g, Pd 10%, dry wt. basis Water ꢀ50%). The solution
was flushed with a balloon of H2 gas. The resulting solution
was stirred for 10 min. When the yellow color of the
solution disappeared, the reaction was completed. Pd/C
was recovered by filtration and reused for other reactions.
Filtrate was concentrated and chromatographed on a silica
gel column eluting with hexane and ethyl acetate (v/v, 9:1).
1
Compound 5b. Yield: 85%; H NMR (CDCl3): d 7.18 (m,
4H), 2.79 (d, J = 4.6 Hz, 1H), 2.36 (d, J = 5.1 Hz, 1H), 2.15
(s, 3H), 1.84 (s, 3H), 1.78 (s, 3H), 1.72 (s, 3H); 13C NMR
(CDCl3): d 204.9, 166.4, 148.8, 148.3, 141.7, 126.8, 126.6,
117.8, 117.7, 84.9, 84.8, 57.0, 56.7, 17.5, 15.9, 14.0, 8.17; IR
m(C@O) 1689 cmÀ1; HRMS for C17H18O2: calcd 254.1307,
obsd 254.1311.
1
1
Compound 6b. Yield: 82%; H NMR (CDCl3): d 7.76 (d,
Compound 2d. Yield: 87%; H NMR (CDCl3): d 8.39 (s,
J = 2.9 Hz, 1H), 7.72 (d, J = 8.1 Hz, 2H), 7.40 (m, 3H), 6.84
(s, 1H), 6.81 (s, 1H), 3.93 (s, 3H), 3.92 (s, 3H), 3.06 (dd,
J = 2.9, 5.0 Hz, 1H), 2.56 (d, J = 5.3 Hz, 1H), 1.88 (s, 3H),
1.85 (s, 3H); 13C NMR (CDCl3): d 204.6, 155.8, 148.4,
148.2, 147.6, 141.1, 140.8, 131.5, 128.9, 128.6, 127.5, 102.9,
86.2, 85.5, 58.3, 56.6, 56.5, 53.4, 15.0, 14.8; IR m(C@O)
1704 cmÀ1; HRMS for C23H22O4: calcd 362.1518, obsd
362.1514.
1H), 8.00 (d, J = 8.2 Hz, 1H), 7.95 (s, 1H), 7.90 (d,
J = 8.3 Hz, 1H), 7.62 (t, J = 8.1 Hz, 1H), 7.55 (t,
J = 7.3 Hz, 1H), 7.36–7.21 (m, 5H), 4.02 (dd, J = 4.6,
8.9 Hz, 1H), 3.87 (dd, J = 8.9, 17 Hz, 1H), 3.46 (dd, J = 4.2,
17 Hz, 1H); 13C NMR (CDCl3): d 206.5, 146.5, 140.0,
137.5, 134.1, 132.8, 130.6, 129.1, 129.0, 128.1, 128.0, 127.3,
126.4, 126.0, 125.6, 124.8, 54.4, 35.5; IR m(C@O)
1716 cmÀ1; HRMS for C19H14O1: calcd 258.1045, obsd
258.1046.
General procedure for the synthesis of benz[f]indenone: To
a 100 mL of round-bottom flask was added b. To t he
solution was added MeOH and hydrochloric acid (2 mL of
HCl in 30 mL of MeOH). After the resulting solution was
refluxed for 6 h, the solution was cooled to rt. The solution
was filtered and the precipitant was washed with methanol.
Dichloromethane was added to extract organic com-
pounds. The dichloromethane extract was dried over
anhydrous MgSO4, filtered, and chromatographed on a
silica gel column eluting with hexane and ethyl acetate (v/v,
9:1).
1
Compound 3d. Yield: 93%; H NMR (CDCl3): d 8.27 (d,
J = 8.4 Hz, 1H), 8.09 (d, J = 8.4 Hz, 1H), 7.66 (t,
J = 8.4 Hz, 1H), 7.56 (t, J = 8.4 Hz, 1H), 7.32–7.20 (m,
5H), 3.95 (dd, J = 4.8, 9.1 Hz, 1H), 3.73 (dd, J = 9.1, 17 Hz,
1H), 3.28 (dd, J = 4.7, 17 Hz, 1H), 3.07 (s, 3H), 2.65 (s, 3H);
13C NMR (CDCl3): d 208.2, 144.5, 140.6, 136.6, 135.6,
132.8, 130.1, 128.9, 128.4, 128.1, 127.1, 126.7, 126.0, 125.6,
124.4, 54.7, 34.2, 14.2, 12.7; IR m(C@O) 1705 cmÀ1; HRMS
for C21H18O: calcd 286.1358, obsd 286.1363.
1
Compound 4d. Yield: 88%; H NMR (CDCl3): d 7.80 (d,
1
Compound 2c. Yield: 84%; H NMR (CDCl3): d 7.94 (s,
J = 8.4 Hz, 1H), 7.73 (d, J = 8.4 Hz, 1H), 7.55–7.35 (m,
12H), 7.19 (m, 5H), 3.87 (dd, J = 5.4, 8.9 Hz, 1H), 3.52 (dd,
J = 9.0, 17 Hz, 1H), 3.22 (dd, J = 5.4, 17 Hz, 1H); 13C
NMR (CDCl3): d 205.1, 144.3, 139.7, 137.6, 136.6, 136.2,
135.7, 132.8, 130.2, 130.1, 129.9, 129.7, 129.0, 128.9, 128.8,
128.6, 128.2, 128.1, 127.9, 127.0, 126.2, 126.0, 54.6, 34.3; IR
m(C@O) 1711 cmÀ1; HRMS for C31H22O: calcd 410.1671,
obsd 410.1676.
1H), 7.89 (d, J = 6.9 Hz, 2H), 7.83 (s, 1H), 7.81 (d,
J = 7.4 Hz, 1H), 7.74 (d, J = 7.9 Hz, 1H), 7.53 (t,
J = 7.1 Hz, 1H), 7.46 (t, J = 6.9 Hz, 1H), 7.46–7.39 (m,
3H), 7.40 (s, 1H); 13C NMR (CDCl3): d 195.2, 143.6, 140.1,
138.6, 131.6, 130.9, 128.9, 128.7, 128.6, 127.3, 127.0, 125.9,
124.6, 121.2; IR m(C@O) 1698 cmÀ1; HRMS for C19H12O:
calcd 256.0888, obsd 256.0883.
1
1
Compound 3c. Yield: 90%; H NMR (CDCl3): d 8.07 (d,
Compound 5d. Yield: 63%; H NMR (CDCl3): d 8.22 (d,
J = 6.8 Hz, 1H), 7.98 (s, 1H), 7.92 (d, J = 7.7 Hz, 1H), 7.88
(d, J = 7.0 Hz, 2H), 7.58 (t, J = 7.0 Hz, 1H), 7.49 (t,
J = 7.1 Hz, 1H), 7.42 (t, J = 7.5 Hz, 2H), 7.34 (t,
J = 7.2 Hz, 1H), 2.92 (s, 3H), 2.58 (s, 3H); 13C NMR
(CDCl3): d 197.2, 141.7, 141.6, 139.1, 136.1, 135.9, 135.8,
134.7, 132.2, 128.7, 128.6, 128.5, 127.5, 126.9, 126.7, 126.3,
125.5, 13.8, 12.0; IR m(C@O) 1694 cmÀ1; HRMS for
C21H16O: calcd 284.1201, obsd 284.1201.
J = 8.6 Hz, 1H), 8.02 (d, J = 8.5 Hz, 1H), 7.59 (t, J =
8.2 Hz, 1H), 7.50 (t, J = 8.2 Hz, 1H), 3.66 (q, J = 7.4 Hz,
1H), 3.03 (s, 3H), 2.85 (q, J = 7.3 Hz, 1H), 2.65 (s, 3H), 1.23
(d, J = 7.2 Hz, 3H), 1.09 (d, J = 7.2 Hz, 3H); 13C NMR
(CDCl3): d 210.2, 149.9, 135.7, 135.3, 132.7, 129.6, 127.9,
127.2, 126.6, 125.5, 124.4, 49.0, 36.1, 18.0, 13.9, 12.7, 10.1;
IR m(C@O) 1707 cmÀ1
238.1358, obsd 238.1360.
;
HRMS for C17H18O: calcd
1
Compound 4c. Yield: 99%; 1H NMR (CDCl3): d 7.69–7.17
(m, 20H); 13C NMR (CDCl3): d 194.8, 142.6, 139.7, 139.3,
136.4, 136.1, 135.5, 135.3, 134.4, 131.6, 130.6, 129.4, 128.6,
128.5, 128.3, 128.2, 128.1, 127.4, 127.3, 126.7, 126.0, 125.9;
Compound 6d. Yield: 85%; H NMR (CDCl3): d 7.43 (s,
1H), 7.32–7.20 (m, 5H), 7.26 (s, 1H), 4.09 (s, 3H), 4.06 (s,
3H), 3.94 (dd, J = 4.5, 9.0 Hz, 1H), 3.69 (dd, J = 9.0, 17 Hz,
1H), 3.27 (dd, J = 4.5, 17 Hz, 1H), 3.01 (s, 3H), 2.60 (s, 3H);
13C NMR (CDCl3): d 208.4, 151.7, 149.3, 144.4, 141.2,
134.7, 132.6, 129.2, 128.7, 128.3, 127.3, 126.6, 104.9, 103.1,
IR m(C@O) 1698 cmÀ1
408.1514, obsd 408.1516.
; HRMS for C31H20O: calcd

D. H. Kim et al. / Tetrahedron Letters 46 (2005) 4627–4631
4631
56.3, 54.9, 34.5, 14.7, 13.2; IR m(C@O) 1709 cmÀ1; HRMS
for C23H22O3: calcd 346.1569, obsd 346.1569.
140.8, 137.8, 136.5, 128.8, 128.3, 127.6, 126.1, 126.0, 125.8,
124.7, 121.9, 103.9, 103.8, 55.9, 38.5, 15.6, 15.3; HRMS for
C23H22O2: calcd 330.1620, obsd 330.1624; decomposed at
230 ꢁC.
General procedure for the synthesis of benz[f]indene: To a
50 mL schlenk flask filled with nitrogen in an ice-bath were
added a solution of 3d (0.28 g, 0.98 mmol) in 15 mL of THF
and LiAlH4 (23 mg, 0.59 mmol). The resulting solution was
allowed to warm to rt. After the solution was stirred for 4 h,
several drops of satd aqueous NH4Cl solution were added.
As the NH4Cl solution was added, fluorescence disap-
peared. The resulting solution was filtered over a MgSO4
pad and the filtrate was evaporated to dryness. The residue
was used for further reactions without further purification.
To a 100 mL round-bottom flask were added the residue,
MgSO4 (5.0 g), and 60 mL of hexane. After the resulting
solution was refluxed, the solution was filtered, evaporated,
and chromatographed on a silica gel column eluting with
hexane and ethyl acetate (v/v, 24:1).
9. Becker, C. L.; McLaughlin, M. L. Synlett 1991, 9, 642.
10. CCDC reference numbers 245437. Crystallographic data
for C31H22: M = 394.49, orthorhombic, P212121, k =
˚
˚
0.71073 A,
T = 293(2) K,
a = 5.9770(10) A,
b =
10.8310(10) A, c = 32.496(2) A, V = 2103.7(4) A , Z = 4,
3
˚
˚
˚
Dcalcd = 1.246 Mg/m3, l = 0.070 mmÀ1
,
F(000) = 832,
crystal size 0.19 · 0.20 · 0.20 mm, h range for data collec-
tion 1.98–26.97ꢁ, index range À7 6 h 6 6, À13 6 k 6 13,
À36 6 l 6 34, 2722 reflections collected, 2722 unique data
(R(int) = 0.0000), refinement method full-matrix least-
squares on F2, data/restraints/parameters 2722/0/280,
goodness-of-fiton F2 0.829, final R indices (I > 2r(I))
R1 = 0.0495, wR2 = 0.1167, largestdifference peak and
Compound 2. Yield: 35%; 1H NMR (CDCl3): d 7.92 (s,
1H), 7.89 (m, 1H), 7.83 (s, 1H), 7.75 (d, J = 7.6 Hz, 2H),
7.47–7.42 (m, 4H), 7.46 (s, 1H), 7.35 (t, J = 7.2 Hz, 1H),
3.99 (s, 2H); Anal. Calcd for C19H14: C, 94.18; H, 5.82.
Found: C, 94.09; H, 5.77; HRMS for C19H14: calcd
242.1096, obsd 242.1100; decomposed at262 ꢁC.
hole 0.258 and À0.264 e A
.
À3
˚
11. (a) Becke, A. D. J. Chem. Phys. 1993, 98, 5648; (b)
Stephens, P. J.; Devlin, F. J.; Chablowski, C. F.; Frisch,
M. J. J. Phys. Chem. 1994, 98, 11623; (c) Hertwig, R. H.;
Koch, W. Chem. Phys. Lett. 1997, 268, 345.
12. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G.
E.; Robb, M. A.; Cheeseman, J. R.; Zakrzewski, V. G.;
Montgomery, J. A., Jr.; Stratmann, R. E.; Burant, J. C.;
Dapprich, S.; Millam, J. M.; Daniels, A. D.; Kudin, K. N.;
Strain, M. C.; Farkas, O.; Tomasi, J.; Barone, V.; Cossi,
M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.;
Clifford, S.; Ochterski, J.; Petersson, G. A.; Ayala, P. Y.;
Cui, Q.; Morokuma, K.; Rega, N.; Salvador, P.; Dannen-
berg, J. J.; Malick, D. K.; Rabuck, A. D.; Raghavachari,
K.; Foresman, J. B.; Cioslowski, J.; Ortiz, J. V.; Baboul,
A. G.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.;
Komaromi, I.; Gomperts, R.; Martin, R. L.; Fox, D. J.;
Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara,
A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen,
W.; Wong, M. W.; Andres, J. L.; Gonzalez, C.; Head-
Gordon, M.; Replogle, E. S.; Pople, J. A. Gaussian, Inc.,
Pittsburgh PA, 2002.
13. Berlman, I. B. Handbook of Fluorescence Spectra of
Aromatic Molecules; Academic: New York, 1971.
14. Fery-Forgues, S.; Lavabre, D. J. Chem. Educ. 1999, 76,
1260.
15. (a) Merlet, S.; Birau, M.; Wang, Z. Y. Org. Lett. 2002, 4,
2157; (b) Marsitzky, D.; Scott, J. C.; Chen, J. P.; Lee, V.
Y.; Miller, R. D.; Setayesh, S.; Muellen, K. Adv. Mater.
2001, 13, 1096.
1
Compound 3. Yield: 70%; H NMR (CDCl3): d 8.03 (m,
2H), 7.69 (d, J = 7.2 Hz, 2H), 7.49 (s, 1H), 7.47 (m, 2H),
7.40 (t, J = 7.8 Hz, 2H), 7.28 (t, J = 7.3 Hz, 1H), 3.81 (s,
2H), 2.73 (s, 3H), 2.64 (s, 3H); 13C NMR (CDCl3): d 146.1,
141.9, 138.9, 136.2, 132.8, 131.5, 128.8, 127.8, 125.9, 125.8,
124.9, 124.6, 124.3, 123.1, 38.4, 15.3, 15.0; HRMS for
C21H18: calcd 270.1409, obsd 270.1405; mp 198 ꢁC.
Compound 4. Yield: 68%; 1H NMR (CDCl3): d 7.71
(d, J = 8.6 Hz, 1H), 7.59 (d, J = 8.6 Hz, 1H), 7.51–7.39
(m, 12H), 7.33–7.10 (m, 5H), 7.05 (s, 1H), 3.67 (s, 2H); 13
C
NMR (CDCl3): d 147.8, 142.2, 139.3, 139.2, 138.8, 135.7,
134.3, 132.3, 131.2, 131.0, 130.1, 128.8, 128.7, 128.6, 128.0,
127.6, 127.4, 126.2, 126.1, 126.0, 125.3, 124.9, 38.8; HRMS
for C31H22: calcd 394.1722, obsd 394.1725; mp 180 ꢁC.
1
Compound 5. Yield: 58%; H NMR (CDCl3): d 7.98 (m,
2H), 7.43 (m, 2H), 6.63 (s, 1H), 3.46 (q, J = 7.2 Hz, 1H),
2.65 (s, 3H), 2.63 (s, 3H), 2.09 (s, 3H), 1.33 (q, J = 7.3 Hz,
3H); 13C NMR (CDCl3): d 151.7, 144.9, 141.4, 131.4, 124.8,
124.6, 124.3, 124.2, 47.2, 16.4, 15.5, 15.2, 14.7; HRMS for
C17H18: calcd 222.1409, obsd 222.1408; mp 66 ꢁC.
1
Compound 6. Yield: 49%; H NMR (CDCl3): d 7.62 (d,
J = 7.7 Hz, 2H), 7.41 (s, 1H), 7.33 (t, J = 7.7 Hz, 2H), 7.21
(s, 2H), 7.20 (t, J = 7.7 Hz, 1H), 3.96 (s, 6H), 3.75 (s, 2H),
2.64 (s, 3H), 2.56 (s, 3H); 13C NMR (CDCl3): d 148.6, 145.2,