Ir-catalyzed direct borylation at the 4-position of pyrene

Article abstract of DOI:10.1021/jo301293w

The first direct borylation of a C-H bond at the 4-position of pyrene was achieved using [Ir(COD)Cl]₂/dtbpy as the catalyst precursor and B₂pin₂ as the boron source. The position-related photophysical properties of pyrene

Full text of DOI:10.1021/jo301293w

Note
pubs.acs.org/joc
Ir-Catalyzed Direct Borylation at the 4‑Position of Pyrene
Zhiqiang Liu,*,† Yuanyuan Wang,† Ying Chen,† Jie Liu,† Qi Fang,† Christian Kleeberg,‡
and Todd B. Marder*,‡,§
†State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China
‡Department of Chemistry, Durham University, Durham, DH1 3LE, United Kingdom
§Institut fur Anorganische Chemie, Julius-Maximilians-Universitat Wurzburg, Am Hubland, 97074 Wurzburg, Germany
̈
̈
̈
̈
S
* Supporting Information
ABSTRACT: The first direct borylation of a C−H bond at the 4-position of pyrene was
achieved using [Ir(COD)Cl]2/dtbpy as the catalyst precursor and B2pin2 as the boron source.
The position-related photophysical properties of pyrene derivatives are reported.
oron plays an important role in modern organic chemistry,
both for synthetic methodology1 and for functional
sequent rearomatization, gives 2,7-substituted pyrenes,24 while
the ruthenium-catalyzed oxidation at the K-region of
pyrene25,26 or Lewis acid catalyzed bromination of 2,7-di-tert-
butyl pyrene can extend pyrene at the 4,5,9,10 positions.27
Itami and co-workers have very recently reported the
palladium-catalyzed oxidative direct arylation of pyrene at the
4-position.28 However, there are no reports of direct borylation
of pyrene at the 4-position due to the steric-selectivity of the Ir-
catalyst mentioned above.
Thus, Marder et al. reported a one-step Ir-catalyzed direct
borylation of pyrene at the 2- or 2,7-positions with high
selectivity,19 which provided a rapid and efficient route to
functionalized pyrenes,29−31 and even rich crystallographic
behaviors.19c Furthermore, the authors also noted that trace
amounts of a triborylated pyrene were observed by EI/MS after
extended reaction times of 3−4 days, when 2.2 mol equiv of
B2pin2 were used, although they had not separated and
characterized it at that time.19a
Herein, we examine the regio-selectivity of the Ir-catalyzed
borylation of pyrene, which has previously been substituted at
the 2,7 positions by bulkyl groups such as tert-butyl and/or
Bpin, and demonstrate the position-related photophysical
properties of pyrene derivatives (Scheme 1).
First, pyrene was selectively mono- or- di-tert-butylated using
tert-butyl chloride and aluminum chloride to afford mono- or
di-tert-butyl-pyrene depending on the number of equivalents of
tert-butyl chloride.32 The orientation of the substituents has
been shown by crystal structure analysis,33 and it is unique,
because of the extreme bulk of the tert-butyl groups, that
electrophilic substitution takes place at the 2,7-positions. In a
typical borylation reaction, equimolar quantities of substrate
and B2pin2 (normally 10 mmol) and a catalytic amount of
[Ir(COD)Cl]2 (1 mol % Ir) and dtbpy (1 mol %) were reacted
B
materials.2−4 In particular, aryl boronates (boronic acids,
boronate esters, and trifluoroborate salts) are widely used as
key intermediates for a variety of cross-coupling reactions.5−7
Boronates can be prepared either from halo-substituted arenes
via reactive lithium or Grignard reagents or via transition metal
catalyzed borylation.1 Recently, the direct borylation of C−H
bonds has attracted great attention.8 Thus, Ishiyama, Miyaura
and Hartwig,9,10 Smith11 and Marder12 and their co-workers
showed that an Ir-complex can be used for borylation of
aromatic C−H bonds under mild conditions. Ground breaking
experimental and theoretical studies have been carried out to
examine the mechanism13,14 and extend the use of this
borylation reaction from aryl and heteroaryl systems to fused
polycyclic aromatics and even polymers.15−21 The Ir-catalyst,
normally prepared in situ via the reaction of [Ir(COD)Cl]2 or
[Ir(COD)OMe]2 with 4,4′-di-tert-butyl-2,2′-bipyridine
(dtbpy), borylates arenes with unusual sterically driven
regioselectively, typically avoiding positions ortho to either
substituents or to ring junctions.8 This selectivity is due to the
crowded nature of the five-coordinate trisboryl species
[Ir(dtbpy)(Bpin)3], which is believed to be the key
intermediate in the catalytic cycle responsible for the C−H
activation.13
Pyrene-based materials for organic electronics have been the
subject of tremendous investigation.22 From a synthetic
viewpoint, the chemistry of pyrene is strongly position-
dependent. The 1-, 3-, 6-, and 8-positions of pyrene are the
active sites for electrophilic aromatic substitution (SEAr)
reactions, and most pyrene derivatives are prepared via such
processes.22 Thus, monobromination is known to occur
preferentially at the C1 position of pyrene.23 For substitution
at the unfavorable 2,7 and 4,5,9,10 positions, an indirect
multistep route normally has to be employed. For example, Pd/
C catalyzed reduction of pyrene with H2 to give 4,5,9,10-
tetrahydropyrene, which followed by substitution and sub-
Received: June 21, 2012
Published: July 20, 2012
© 2012 American Chemical Society
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dx.doi.org/10.1021/jo301293w | J. Org. Chem. 2012, 77, 7124−7128

The Journal of Organic Chemistry
Note
a
Scheme 1. Borylation of Pyrene Derivatives
a
(a) t-BuCl, AlCl3, DCM, rt, 16 h; (b) B2pin2, [Ir(COD)Cl]2, dtbpy, hexane, 80 °C, 48 h; (c) 4-bromo-toluene, Pd(PPh3)4, Na2CO3, toluene/H2O,
80 °C, 16 h.
in hexane (15 mL) under N2 at 80 °C for 48 h. When 2-tert-
butyl-pyrene was used, the Ir-catalyzed monoborylation clearly
took place at the 7-position in nearly 100% yield, confirmed by
NMR spectroscopy and crystal structure analysis.19b The
borylation of di-tert-butylpyrene was also quite clean, affording
1 in 52% yield after workup. Although the yield is moderate,
the product is very easily purified, and most of the unreacted di-
tert-butylpyrene can be recovered and recycled. Further efforts
to increase the yield by using larger amounts of B2pin2 or
extending the reaction time always increased the quantity of
byproduct (i.e., a mixture of diborylated pyrenes).
occupied. A related finding in the borylation of phenacenes
was recently reported.35
Considering that previous reports indicated relatively
sluggish reactivity of 2,7-di-Bpin-pyrene in Suzuki−Miyaura
cross-coupling reactions,19b,36 compared with -B(OH)2 or
-BF3K analogues,19b the reactivity of the 4-Bpin-substituted
pyrenes was also examined. First, 4-bromo-toluene and 1 were
used as coupling partners, employing the Pd(PPh3)4-Na2CO3-
toluene system for Suzuki−Miyaura coupling. This reaction
worked well and gave the 4-arylated product 2 in high yield,
indicating good reactivity of the 4-Bpin group. To our surprise,
compound 3 also coupled readily with 4-bromotoluene under
the same conditions. Interestingly, all three Bpin groups reacted
giving 2,4,7-tri-4-tolylpyrene 4 in 75% yield. Compared with S-
2, it appears that the lower symmetry of the 4-substituted
derivatives may activate the Bpin groups at the 2,7-postions. In
contrast with the reported 2,7-Ph2-pyrene,36b in the solid state,
the tolyl moieties at the 2,7-positions in 4 are nearly coplanar
with the pyrene skeleton, with angles between the respective
mean planes of 16.67(7) and 3.98(9)°. However, maybe
because of steric hindrance, the tolyl groups at the 4-position
are twisted, with angles between the respective mean planes of
64.8(1)° in 2 and 54.58(6)° in 4 (Figure S5, Supporting
Information). Note that 2 forms a 1:1 π-stacked cocrystal with
C6F6 (see Figure S6, Supporting Information, ref 19c and
references therein).
The product of the borylation of di-tert-butylpyrene was fully
characterized by NMR, MS, and elemental analysis, and its
structure was confirmed by single-crystal X-ray diffraction,
demonstrating that this borylation occurred exclusively at the 4-
1
position as expected. Its H NMR spectral pattern is quite
similar with that reported for 4-bromo-2,7-di-tert-butylpyrene.34
In the single crystal structure (Figure S4, Supporting
Information) of 1, two types of disorder involving methyl
and Bpin groups precluded our obtaining highly accurate
structural parameters, but the data confirmed that boron is
connected to the 4-position of pyrene. Interestingly, the space
group of the crystals of 1 is CC, such that all molecules of 1 pack
along one polar axis.
Encouraged by this result, the borylation of 2,7-di-Bpin-
pyrene (S-2) under the same conditions was examined, and
2,4,7-tri-Bpin-pyrene (3) was successfully isolated in 62% yield.
The positions of borylation in compound 3 were also
confirmed by single-crystal X-ray diffraction (Figure S4,
Supporting Information). Compound 3 crystallizes in the
noncentrosymmetric spacegroup P21; however, it is partly
disordered. The disorder was refined employing a suitable split-
atom model. The three borolane rings are nearly coplanar with
the pyrene skeleton as indicated by the small angles of 5.3(9)°
to 19.3(7)° between the mean plane of the pyrene skeleton and
the respective O−B−O planes. The bond lengths of the three
B−C bonds are in a narrow range around 1.57 Å. Thus, Ir-
catalyzed borylation can also occur at a C−H bond ortho to a
ring junction when more sterically favored positions are
Pyrene is a prototypical and widely used fluorophore.22 The
photophysical properties of pyrene derivatives can be tuned not
only by the substituent but also by its position. In our recent
paper,30 we demonstrated and discussed the differences
between 1- and 2-substituted pyrene derivatives. Although
several 4-subsitituted pyrenes have been reported,25−28,37 few
studies of the relationship between substitution position and
basic photophysical properties have appeared.37 We therefore
recorded absorption and emission spectra, fluorescence
quantum yields and lifetimes of compounds 1−4, and for
comparison, 2,7-tBu2-pyrene (S-1), 2-tBu-7-Bpin-pyrene (5)19b
and 2-tBu-6-Bpin-pyrene (6)38 (Figure 1 and Table 1).
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Note
As shown in Figure 1, the absorption spectrum of 2-Bpin-7-t-
butyl-pyrene (5) is quite similar to that of unsubstituted pyrene
with only a 3 nm red-shift.30 However, borylation at the “1-
position” (2-t-butyl-6-Bpin-pyrene, 6) causes a red-shift of 17
nm and a 6 fold increase in ε for the lowest energy transtion.
These are in accordance with the observation that substitution
at the 2,7-positions has little influence on the S2 ← S0
absorption but a large influence on the S1 ← S0 absorption,
whereas 1-substitution influences both S2 ← S0 and S1 ← S0
absorptions.30 However, the absorption maximum of the 4-
Bpin substituted compound 1 is fairly similar to that of 6,
including the S1 ← S0 absorption at 380 nm, but its pattern is
quite different. The main S2 ← S0 absorption band (i.e., 330−
360 nm for 1) has become a broad band comprising two weak
peaks with much lower extinction coefficients. The absorption
of tri-Bpin substituted 3 shows a significant red-shift vs the
other Bpin derivatives, and again, evidence that symmetry
breaking makes the S1 ← S0 transition more allowed.
For the emission spectra of the substituted compounds, some
of the fine structure observed for pyrene is lost, and the main
emission peaks are significantly red-shifted. The spectral profile
for compound 1 is nearly the same as that of 6. Compound 3
fluoresces at longer wavelength than the others but shows a
similar pattern to that of 5. In addition, the fluorescence
lifetimes of 4-substituted 1 and 3 are also similar to that of 6,
but only half of that of 5. For the tolyl substituted compounds 2
and 4, the typical S2 ← S0 absorption observed in pyrene
around 334 nm appears as broad bands with unresolved
vibrational structures, and the weak S1 ← S0 pyrene absorption
at 372 nm was not observed.
In summary, we have shown that an Ir catalyst will borylate
pyrene at the 4-position, which is ortho to ring junctions, if the
2- and 7-positions are occupied. Moreover, the 4-Bpin
compounds show good reactivity for Suzuki−Miyaura coupling,
and the asymmetry induced seems to activate Bpin groups at
2,7-positions as well. The absorption and emission properties of
4-substituted compounds also show much similarity to those of
1-substituted pyrenes, i.e., spectral patterns and peak positions.
We expect this borylation process to be of use in extending the
chemistry of pyrene.
Figure 1. Normalized absorption (top) and emission (bottom) spectra
of pyrene and 1-, 2-, and 4-borylated pyrenes.
Table 1. Spectroscopic Data for Pyrene Derivatives in
Degassed Hexane
λabs
/
λem
/
τ/
ns
R
nm
ε/mol−1 cm−1
L
nm
Φ
S-1
1
R2 = t-butyl
R7 = t-butyl
R4 = H
376
337
322
380
350
336
342
328
800
67000
45000
2600
378
388
398
381
391
402
381
391
400
402
425
450
420
0.42
78
45
60
42
52
74
40
EXPERIMENTAL SECTION
■
All reactions were carried out under a nitrogen atmosphere using
standard Schlenk techniques. NMR spectra were obtained in CDCl3
using 400 MHz spectrometers. Chemical shifts are reported relative to
tetramethylsilane and are referenced to residual proton or carbon
resonances in CDCl3. High-Res MS (HRMS) were record in MALDI
(DHB matrix, FTMS) or ESI (Q-TOF positive ion) modes. The
melting points were measured on a DSC at a heating rate of 20 °C
min−1 under a nitrogen atmosphere. UV−vis absorption spectra and
fluorescence emission spectra were recorded with C = 1.0 × 10−5
mol·L−1 in hexane. For luminescence quantum yield and lifetime
measurements, dilute solutions (C = 2.0−5.0 × 10−6) of the
compounds were carefully degassed via three freeze−pump−thaw
cycles to remove any dissolved oxygen.
4-Bpin-2,7-di-tert-butylpyrene (1). In a dry nitrogen-filled
glovebox, the precatalyst [Ir(COD)Cl]2 (33.5 mg, 0.1 mmol Ir),
ligand dtbpy (27 mg, 0.1 mmol) and a small amount of B2pin2 (ca. 50
mg) were mixed in 2 mL of hexane in a Schlenk tube and stirred
vigorously until the solution turned brown. Then di-tert-butylpyrene
(S-1, 3.14 g, 10.0 mmol) and B2pin2 (2.54 g, 10.0 mmol) and 20 mL of
hexane were add into this tube under N2, the tube was sealed with
Teflon cap, and the mixture was stirred at 80 °C for 48 h to give a dark
red solution. The mixture was filtered through a short silica pad to
remove the Ir-containing catalyst and then concentrated. Removal of
R2 = t-butyl
R7 = t-butyl
R4 = Bpin
0.66
0.55
0.62
0.44
0.49
0.83
34000
37000
60000
48000
2
R2 = t-butyl
R7 = t-butyl
R4 = p-tolyl
R2 = Bpin
R7 = Bpin
R4 = Bpin
R2 = p-tolyl
R7 = p-tolyl
R4 = p-tolyl
R2 = t-butyl
R7 = Bpin
R4 = H
3
399
347
337
345
336
320
385
337
322
381
352
335
5000
29000
55000
50000
64000
62000
1200
4
5
386
408
432
382
391
402
74000
45000
7300
6
R2 = t-butyl
R6 = Bpin
R7 = R4 = H
69000
51000
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The Journal of Organic Chemistry
Note
the volatiles and subsequent column chromatography on silica gel,
eluting with hexane: CHCl3 = 1:1, resulted in two colorless
compounds, 1 and S-1 in 52 and 45% yields, respectively. The
product was recrystallized from hexane to give colorless prismatic
crystals: mp 173−174 °C; 1H NMR (CDCl3, 400 MHz), δ = 9.18 (d, J
= 2 Hz, 1 H), 8.66 (s, 1 H), 8.23 (d, J = 2 Hz, 1 H), 8.19 (d, J = 2 Hz,
1 H), 8.16 (d, J = 2 Hz, 1 H), 8.00 (AB quartet), 1.59 (s, 9H), 1.56 (s,
9H), 1.51 (12 H); 13C{1H} NMR (CDCl3, 125 MHz), δ = 148.5,
148.4, 138.5, 133.1, 130.8, 130.7, 130.0, 127.9, 126.7, 124.0, 123.5,
122.9, 122.81, 122.75, 121.9, 83.8, 35.4, 35.2, 31.97, 31.95, 25.1. Anal.
Calcd: for C30H37BO2; C 81.81, H 8.47; found C, 81.68; H, 8.43.
HRMS (MALDI/DHB) Calcd for C30H3710BO2 440.2881; found
440.2887. HRMS (ESI) Calcd for C30H3810BO2 441.2965; found
441.2975.
4-Tolyl-2,7-di-tert-butylpyrene (2). Compound 1 (0.40 g, 1.0
mmol) and 4-bromo-toluene (0.34 g, 2.0 mmol) were placed in a 100
mL Schlenk tube, which was evacuated and purged with nitrogen gas
three times. Pd(PPh3)4 (12 mg, 0.01 mmol), toluene (∼10 mL) and a
saturated aqueous solution of Na2CO3 (∼0.5 mL) were added under
nitrogen. The tube was sealed with a Teflon cap and stirred at 80 °C
for 16 h before it was quenched. The mixture was extracted with
CH2Cl2, dried over MgSO4, and concentrated in vacuo. Purification by
column chromatography (silica gel using chloroform-petroleum ether
(1: 6)) gave a colorless oil in 64% yield. The product was recrystallized
from hexane with addition of hexafluorobenzene to give colorless
needle-like crystals: mp 121−123 °C; 1H NMR (CDCl3, 400 MHz), δ
= 8.29 (d, J = 2 Hz, 1 H), 8.20 (d, J = 1 Hz, 1H), 8.18 (s, 2 H), 8.05
(d, J = 2 Hz, 2 H), 7.974 (s, 1 H), 7.60 (d, J = 8 Hz, 2 H), 7.38 (d, J =
8 Hz, 2 H), 2.52 (s, 3 H), 1.58 (s, 9 H), 1.48 (s, 9 H); 13C{1H} NMR
(CDCl3, 100 MHz), δ = 148.8, 148.3, 139.5, 138.2, 137.0, 131.0, 130.8,
130.6, 130.1, 129.9, 129.1, 128.4, 127.9, 127.7, 127.2, 123.2, 122.4,
122.1, 121.8, 121.2, 35.3, 35.2, 32.0, 31.9, 21.3. Anal. Calcd: for
C31H32: C 92.03, H 7.97; found C 91.97; H, 8.01. HRMS (MALDI/
DHB) Calcd for C31H32 404.2499; found 404.2496. HRMS (ESI)
Calcd for C31H33 405.2582; found 405.2547.
H), 7.38 (m, 4 H), 7.31 (d, J = 8 Hz, 2 H), 2.51 (s, 3 H), 2.47 (s, 3 H),
2.43 (s, 3 H); 13C {H} NMR (CDCl3, 100 MHz), δ =140.1, 139.0,
138.9, 138.7, 137.9, 137.28, 137.25, 137.14, 131.7, 131.5, 131.3, 130.9,
130.0, 129.8, 129.7, 129.3, 128.3, 128.1, 127.93, 127.85, 127.75, 124.1,
123.9, 123.74, 123.69, 123.5, 123.2, 122.8, 21.4, 21.2, 21.2. Anal. Calcd:
for C37H28: C 94.03, H 5.97; found C 94.07; H, 5.93. HRMS
(MALDI/DHB) Calcd for C37H28 472.2182; found 472.2185. HRMS
(ESI) Calcd for C37H29 473.2269; found 473.2261.
ASSOCIATED CONTENT
* Supporting Information
■
S
Details of NMR, HRMS, and crystallographic data in CIF
format for 1−4, absorption and excitation spectra of 1, 3, 5, 6,
and absorption and emission spectra of 2 and 4. This material is
available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: zqliu@sdu.edu.cn; todd.marder@uni-wuerzburg.de.
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
Financial support from the National Natural Science
Foundation of China (20802026, 50803033) is gratefully
acknowledged. Z.L. thanks the Royal Society and BP for a
China Incoming Fellowship to support collaboration with Prof.
T. B. Marder at Durham University (U.K.). T.B.M. thanks
AllyChem Co., Ltd. for a generous gift of B2pin2, the Royal
Society for a Wolfson Research Merit Award, the Alexander von
Humboldt Foundation for a Research Award, EPSRC for an
Overseas Research Travel Grant, and the Royal Society of
Chemistry for a Journals Grant for International Authors.
2,4,7-Tri-Bpin-pyrene (3). In a dry, nitrogen-filled Schlenk tube,
in a glovebox, the precatalyst [Ir(COD)Cl]2 (33.5 mg, 0.1 mmol Ir),
ligand dtbpy (27 mg, 0.1 mmol) and a small amount of B2pin2 (ca. 50
mg) were mixed in 2 mL of hexane and stirred vigorously until the
solution turned brown. Then 2,7-di-Bpin-pyrene (S-2) (2.27 g, 5
mmol), B2pin2 (2.54 g, 10 mmol) and 20 mL of hexane were added
under N2 into this tube, and the system was sealed with a Teflon cap
and stirred at 80 °C for 48 h to give a dark red solution. The mixture
was filtered through a short silica pad to remove the Ir-containing
catalyst and then concentrated. Removal of the volatiles and
subsequent column chromatography on silica gel, eluting with
hexane:CHCl3 = 1:1, resulted in two colorless compounds, 3 and S-
2 in 62 and 30% yields, respectively. The product was recrystallized
REFERENCES
■
(1) Hall, D. G. Boronic Acids: Preparation and Applications in Organic
Synthesis, Medicine and Materials, 2nd ed.; Wiley-VCH: Weinheim,
2011.
(2) (a) Entwistle, C. D.; Marder, T. B. Chem. Mater. 2004, 16, 4574.
(b) Entwistle, C. D.; Marder, T. B. Angew. Chem., Int. Ed. 2002, 41,
2927.
(3) Hudson, Z. M.; Wang, S. Acc. Chem. Res. 2009, 42, 1584.
(4) Wade, C. R.; Broomsgrove, A. E. J.; Aldridge, S.; Gabbaï, F. P.
Chem. Rev. 2010, 110, 3958.
(5) Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457.
(6) Chan, D. M. T.; Monaco, K. L.; Li, R.; Bonne, D.; Clark, C. G.;
Lam, P. Y. S. Tetrahedron Lett. 2003, 44, 3863.
(7) Sibi, M. P.; Tatamidani, H.; Patil, K. Org. Lett. 2005, 7, 2571.
(8) Mkhalid, I. A. I.; Barnard, J. H.; Marder, T. B.; Murphy, J. M.;
Hartwig, J. F. Chem. Rev. 2010, 110, 890.
(9) Ishiyama, T.; Takagi, J.; Ishida, K.; Miyaura, N.; Anastasi, N. R.;
Hartwig, J. F. J. Am. Chem. Soc. 2002, 124, 390.
(10) Ishiyama, T.; Takagi, J.; Hartwig, J. F.; Miyaura, N. Angew.
Chem., Int. Ed. 2002, 41, 3056.
(11) Cho, J.-Y.; Tse, M. K.; Holmes, D.; Maleczka, R. E., Jr.; Smith,
M. R., III Science 2002, 295, 305.
(12) Nguyen, P.; Blom, H. P.; Westcott, S. A.; Taylor, N. J.; Marder,
T. B. J. Am. Chem. Soc. 1993, 115, 9329.
(13) Tamura, H.; Yamazaki, H.; Sato, H.; Sakaki, S. J. Am. Chem. Soc.
2003, 125, 16114.
(14) Boller, T. M.; Murphy, J. M.; Hapke, M.; Ishiyama, T.; Miyaura,
N.; Hartwig, J. F. J. Am. Chem. Soc. 2005, 127, 14263.
(15) Ishiyama, T.; Takagi, J.; Yonekawa, Y.; Hartwig, J. F.; Miyaura,
N. Adv. Synth. Catal. 2003, 345, 1103.
1
from hexane to give colorless prismatic crystals: mp 260−262 °C; H
NMR (CDCl3, 400 MHz), δ = 9.43 (s, 1 H), 8.69 (s, 1 H), 8.66 (s, 1
H), 8.62 (s, 1 H), 8.58 (s, 1 H), 8.05 (AB quartet, 2 H), 1.51 (s, 12 H),
1.45 (s, 12 H), 1.44 (12 H); 13C{1H} NMR (CDCl3, 100 MHz), δ =
138.3, 133.2, 132.5, 132.1, 132.0, 131.03, 130.96, 130.8, 130.0, 128.1,
127.4, 127.0, 126.3, 84.1, 84.0, 25.11, 25.08, 25.05. Anal. Calcd: for
C34H43B3O6; C 70.39, H 7.47; found C, 70.42; H, 7.45. HRMS (ESI)
Calcd for C34H44B3O6 581.3417; found 581.3414.
2,4,7-Tri-4-tolyl-pyrene (4). Compound 3 (0.58 g, 1.0 mmol)
and 4-bromo-toluene (1.00 g, 6.0 mmol) were placed in a 100 mL
Schlenk tube, which was evacuated and purged with nitrogen gas three
times. Pd(PPh3)4 (12 mg, 0.01 mmol), toluene (∼10 mL) and a
saturated aqueous solution of Na2CO3 (∼0.5 mL) were added under
nitrogen. The tube was sealed with a Teflon cap and stirred at 80 °C
for 16 h before it was quenched. This mixture was extracted with
dichloromethane, dried over MgSO4, and concentrated in vacuo.
Purification by column chromatography (silica gel using chloroform/
petroleum ether (1:6)) gave a colorless oil in 75% yield. The product
was recrystallized from toluene to give colorless single crystals: mp
1
202−204 °C; H NMR (CDCl3, 400 MHz), δ = 8.43 (d, J = 1 Hz, 1
H), 8.39 (d, J = 1 Hz, 1H), 8.38 (s, 2 H), 8.15 (s, 2 H), 8.06 (d, 1 H),
7.80 (d, J = 8 Hz, 2 H), 7.66 (d, J = 8 Hz, 2 H), 7.62 (d, J = 8 Hz, 2
(16) Ishiyama, T.; Nobuta, Y.; Hartwig, J. F.; Miyaura, N. Chem.
Commun. 2003, 2924.
7127
dx.doi.org/10.1021/jo301293w | J. Org. Chem. 2012, 77, 7124−7128

The Journal of Organic Chemistry
Note
(17) Cho, J.-Y.; Iverson, C. N.; Smith, M. R., III J. Am. Chem. Soc.
2000, 122, 12868.
(18) Mkhalid, I. A. I.; Coventry, D. N.; Albesa-Jove, D.; Batsanov, A.
S.; Howard, J. A. K.; Perutz, R. N.; Marder, T. B. Angew. Chem., Int. Ed.
2006, 45, 489.
(19) (a) Coventry, D. N.; Batsanov, A. S.; Goeta, A. E.; Howard, J. A.
K.; Marder, T. B.; Perutz, R. N. Chem. Commun. 2005, 2172.
(b) Crawford, A. G.; Liu, Z.; Mkhalid, I. A. I.; Thibault, M.-H.;
Schwarz, N.; Alcaraz, G.; Steffen, A.; Collings, J. C.; Marder, T. B.
Chem.Eur. J. 2012, 18, 5022. (c) Batsanov, A. S.; Howard, J. A. K.;
́
Albesa-Jove, D.; Collings, J. C.; Liu, Z.; Mkhalid, I. A. I.; Thibault, M.-
H.; Marder, T. B. Cryst. Growth Des. 2012, 12, 2794.
(20) Jo, T. S.; Kim, S. H.; Shin, J.; Bae, C. J. Am. Chem. Soc. 2009,
131, 1656.
(21) Yamaguchi, R.; Hiroto, S.; Shinokubo, H. Org. Lett. 2012, 14,
2472.
(22) Figueira-Duarte, T. M.; Mullen, K. Chem. Rev. 2011, 111, 7260.
̈
(23) Vollmann, H.; Becker, H.; Corell, M.; Streeck, H. Justus Liebigs
Ann. Chem. 1937, 531, 1.
(24) (a) Lee, H.; Harvey, R. G. J. Org. Chem. 1986, 51, 2847.
(b) Connor, D. M.; Allen, S. D.; Collard, D. M.; Liotta, C. L.;
Schiraldi, D. A. J. Org. Chem. 1999, 64, 6888. (c) Godinez, C. E.;
Zepeda, G.; Garcia-Garibay, M. A. J. Am. Chem. Soc. 2002, 124, 4701.
(25) Hu, J.; Zhang, D.; Harris, F. W. J. Org. Chem. 2005, 70, 707.
(26) (a) Zophel, L.; Beckmann, D.; Enkelmann, V.; Chercka, D.;
̈
Rieger, R.; Mullen, K. Chem. Commun. 2011, 47, 6960. (b) Zophel, L.;
̈
̈
Enkelmann, V.; Rieger, R.; Mullen, K. Org. Lett. 2011, 13, 4506.
(27) Hu, J. Y.; Era, M.; Elsegood, M. R. J.; Yamato, T. Eur. J. Org.
Chem. 2010, 2010, 72.
̈
(28) Mochida, K.; Kawasumi, K.; Segawa, Y.; Itami, K. J. Am. Chem.
Soc. 2011, 133, 10716.
(29) (a) Wan, S.; Guo, J.; Kim, J.; Ihee, H.; Jiang, D. Angew. Chem.,
Int. Ed. 2008, 47, 8826. (b) Wan, S.; Guo, J.; Kim, J.; Ihee, H.; Jiang, D.
Angew. Chem., Int. Ed. 2009, 48, 5439.
(30) Crawford, A. G.; Dwyer, A. D.; Liu, Z.; Steffen, A.; Beeby, A.;
Palsson, L.-O.; Tozer, D. J.; Marder, T. B. J. Am. Chem. Soc. 2011, 133,
̊
13349.
(31) Gao, L.; Peay, M. A.; Partyka, D. V.; Updegraff, J. B., III; Teets,
T. S.; Esswein, A. J.; Zeller, M.; Hunter, A. D.; Gray, T. G.
Organometallics 2009, 28, 5669.
(32) Berg, A.; Jakobsen, H. J.; Johansen, S. R. Acta Chem. Scand.
1969, 23, 567.
(33) Hazell, A. C.; Lomborg, J. G. Acta Crystallogr., Sect. B: Struct.
Crystallogr. Cryst. Chem. 1972, 28, 1059.
(34) Yamato, T.; Miyazawa, A.; Tashiro, M. J. Org. Chem. 1992, 57,
266.
(35) Hitosugi, S.; Nakamura, Y.; Matsuno, T.; Nakanishi, W.; Isobe,
H. Tetrahedron Lett. 2012, 53, 1180.
(36) (a) Wanninger-Weiß, C.; Wagenknecht, H.-A. Eur. J. Org. Chem.
2008, 2008, 64. (b) Qiao, Y.; Zhang, J.; Xu, W.; Zhu, D. Tetrahedron
2011, 67, 3395.
(37) (a) Filichev, V. V.; Astakhova, I. V.; Malakhov, A. D.; Korshun,
V. A.; Pedersen, E. B. Chem.Eur. J. 2008, 14, 9968. (b) Astakhova, I.
V.; Lindegaard, D.; A. Korshun, V. A.; Wengel, J. C. Chem. Commun.
2010, 46, 8362.
(38) Figueira-Duarte, T. M.; Simon, S. C.; Wagner, M.; Druzhinin, S.
I.; Zachariasse, K. A.; Mullen, K. Angew. Chem., Int. Ed. 2008, 47,
̈
10175.
7128
dx.doi.org/10.1021/jo301293w | J. Org. Chem. 2012, 77, 7124−7128