Synthesis and evaluation of thiophene-based organic dyes containing a rigid and nonplanar donor with secondary electron donors for use in dye-sensitized solar cells

Article abstract of DOI:10.1002/ejoc.201501190

We demonstrate herein the divergent synthesis of six dyes containing our originally developed rigid and nonplanar donor with three different secondary electron donors (SEDs), namely thiophene, 4-methoxybenzene, and diphenylethene. Evaluation of the photop

Full text of DOI:10.1002/ejoc.201501190

DOI: 10.1002/ejoc.201501190
Full Paper
Solar Cells
Synthesis and Evaluation of Thiophene-Based Organic Dyes
Containing a Rigid and Nonplanar Donor with Secondary
Electron Donors for Use in Dye-Sensitized Solar Cells
Shinichiro Fuse,*[a][‡] Ryota Takahashi,[a] Masato M. Maitani,[a] Yuji Wada,[a] Tatsuo Kaiho,[b]
Hiroshi Tanaka,[a] and Takashi Takahashi[c]
Abstract: We demonstrate herein the divergent synthesis of six depended on their structure and position of attachment. The
dyes containing our originally developed rigid and nonplanar introduction of the thiophene SED to D4π4A2, which we previ-
donor with three different secondary electron donors (SEDs), ously reported to be our best dye, resulted in an increased Jsc.
namely thiophene, 4-methoxybenzene, and diphenylethene. The dye-sensitized solar cell (DSSC) prepared by using dye 2b,
Evaluation of the photophysical properties of the synthesized which contains the thiophene SED, shows a higher power con-
dyes revealed that the introduction of the SEDs resulted in an version efficiency (PCE; η = 4.62 0.02 %) and a higher incident
increased absorbance in the 350–450 nm region. The influence photon-to-current conversion efficiency (IPCE) in the region
of the SEDs on the electrochemical and photovoltaic properties 300–600 nm than D4π4A2.
Introduction
azine,[17] diphenylamine,[19] julolidine,[20] and ethene[21] groups
have been reported. In particular, Chen and co-workers re-
ported that the introduction of a diphenylethene, which is
found in high-performance organic indoline dyes,[22,23] into the
dye TPAR1 (Figure 1, a) resulted in increases in both the Voc and
the short-circuit current density (Jsc) of DSSCs.[24]
We have previously reported the rapid synthesis of metal-
free organic donor–π–acceptor (D–π–A) dyes for use in
DSSCs.[25–28] In the course of our study, we synthesized D–π–
A dyes containing our originally designed rigid and nonplanar
donors (Figure 1, b, Type I and II) and evaluated their photovol-
taic properties.[27] Most Type I dyes exhibit low PCEs probably
due to a less-positive HOMO level, and the best dye, D4π4A2,
is of the Type II variety. To further improve the PCEs of DSSCs,
we decided to introduce SEDs into our D–π–A dyes. Herein we
wish to report the divergent synthesis of six dyes, 2a–c (Type I)
and 3a–c (Type II), containing the SEDs thiophene, 4-methoxy-
benzene, or diphenylethene (Figure 1, c). In addition, we also
report on the photophysical, electrochemical, and photovoltaic
properties of the synthesized dyes to elucidate their structure–
property relationships.
Dye-sensitized solar cells (DSSCs) have garnered considerable
attention due to their high power conversion efficiencies (PCEs),
simple fabrication procedures, and low production costs.[1–5] As
sensitizers, dye molecules play a crucial role in DSSCs.[6,7] The
most common, readily available, high-performing dyes are the
ruthenium-centered polypyridyls.[6,7] Metal-free organic dyes
are a very important class of compounds owing to their large
molar absorptivity, design flexibility, and the potentially lower
production costs compared with the polypyridyl Ru dyes.[8–12]
The creation of high-performance organic dyes with excellent
PCEs is important for the further improvement of DSSCs.
In 1995, Bignozzi and co-workers reported the introduction
of a secondary electron donor (SED) moiety into the tris(bipyr-
idine)ruthenium dye, which led to an extremely long-lived
charge-separated pair with an improved open-circuit voltage
(Voc).[13] Similar reports have since cited the use of ruthenium-
containing dyes.[14–16] With respect to metal-free organic dyes,
the introduction of SEDs such as carbazole,[17,18] phenothi-
[a] Department of Applied Chemistry, Tokyo Institute of Technology,
2-12-1, Ookayama, Meguro-ku, Tokyo 152-8552, Japan
[b] Kanto Natural Gas Development Co., Ltd.,
Brine Resources Research & Development Division,
Chiba 297-8550, Japan
Results and Discussion
We planned to synthesize six dyes, 2a–c and 3a–c, by divergent
approaches involving sequential Suzuki–Miyaura (SM) coupling
reactions[29,30] of aromatic scaffold 1, a subsequent Knoeven-
agel condensation, and finally the removal of the tert-butyl
group (Scheme 1). We considered compounds 1a–1d, each of
which bear two halogen atoms, as candidates for the aromatic
scaffold. Both halogen atoms X1 and X2 are located in para
positions with respect to the amino group in the scaffolds 1a–
[c] Yokohama University of Pharmacy,
601, Matano-cho, Totsuka-ku, Yokohama, Kanagawa 245-0066, Japan
[‡] Present address: Chemical Resources Laboratory,
Tokyo Institute of Technology,
4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
E-mail: sfuse@res.titech.ac.jp
http://syn.res.titech.ac.jp/
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/ejoc.201501190.
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1d. Our preliminary investigation revealed that the C–X1 bond
of 1 is less reactive (more electron-rich) than the C–X2 bond
towards oxidative addition of a palladium catalyst. This is proba-
bly because the lone pair of the nitrogen atom and the π orbital
of aromatic ring A lie in a common plane, whereas the π orbital
of aromatic ring B tends to lie perpendicular to the lone pair of
the nitrogen atom to minimize steric repulsion. Therefore, we
considered that the chemoselective SM coupling reaction
might be achieved by using the scaffold 1c with two iodo
groups. However, we did not use 1c due to its difficult prepara-
tion. Our preliminary experiments also revealed that when X1 =
Br, the oxidative addition of the deactivated aryl A–Br did not
proceed smoothly and an unsatisfactory yield was observed
(<15 %). Thus, we chose to use neither 1b nor 1d, which con-
tain the deactivated aryl A–Br moiety. For these reasons, 1a
bearing both an iodo and a bromo group was selected as the
scaffold. The key to success was to achieve selective reaction of
the carbon–iodine bond, which is more deactivated by electron
donation from the nitrogen atom, without affecting the car-
bon–bromide bond, which is less deactivated by the nitrogen
atom in the first SM coupling reaction.
The aromatic scaffold 1a was prepared from compound 6[31]
by a chemoselective Buchwald–Hartwig coupling reaction[32,33]
and subsequent regioselective iodination, as shown in
Scheme 2.
Figure 1. Metal-free organic D–π–A dyes containing the SED moiety (FF = fill
factor).
Scheme 2. Preparation of the aromatic scaffold 1a (dppf = 1,1′-bis(diphenyl-
phosphanyl)ferrocene).
Scheme 1. Divergent synthesis of six D–π–A dyes 2a–2c and 3a–3c containing SEDs based on the aromatic scaffold 1 (Bu = butyl; Pin = pinacol).
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The key chemoselective SM coupling of the aromatic scaffold
1a with 8–11 was performed as shown in Scheme 3. Pd(OAc)2
(10 mol-%) and [(tBu3P)H]BF4 (30 mol-%) were added to a
stirred solution of aryl iodide 1a (1 equiv.), boronic acids or
boronic acid pinacol esters 8–11 (2 equiv.), and base (Na2CO3
or K2CO3) in THF/water (1:1). After a standard work-up proce-
dure and silica gel column chromatographic separation, the de-
sired coupling products 12–15 were obtained in satisfactory-
to-good yields. With respect to the coupling reaction between
1a and 11, we attempted to use the corresponding cyano-
acrylic acid tert-butyl ester instead of aldehyde 11, but this re-
sulted in a decreased yield (24 %). Thus, we employed aldehyde
11 for this coupling reaction.
Scheme 4. Second SM coupling of the aryl bromides 12–15 with 4 and 8–
10 (BRSM = based on recovered starting material).
cant increase in their near-UV absorbance (Table 1, entries 2
and 3 vs. 8). On the other hand, the introduction of the diphen-
ylethene SED significantly decreased the visible absorbance
whereas the introduction of this SED slightly decreased the
near-UV absorbance (entry 1 vs. entry 8). A different tendency
was observed in terms of the absorbance of Type II dyes. The
introduction of the diphenylethene and 4-methoxybenzene
SEDs only increased the near-UV absorbance (entries 4 and 6
vs. 7), whereas the introduction of the thiophene SED increased
both the visible and near-UV absorbance (entry 5 vs. entry 7).
In terms of the visible absorption wavelength, the introduc-
tion of the SEDs resulted in no significant change for either
Type I or II dyes (entries 1–3 vs. entry 8, entries 4–6 vs. entry 7).
In terms of near-UV absorption wavelength, the introduction of
the diphenylethene SED resulted in a 25–29 nm redshift (en-
try 1 vs. entry 8, entry 4 vs. entry 7), whereas the introduction
of the other SEDs resulted in a 7–16 nm redshift (entries 2 and
3 vs. entry 8, entries 5 and 6 vs. entry 7).
Scheme 3. First chemoselective SM coupling of the aromatic scaffold 1a with
8–11. Ac = acetyl.
The second SM coupling of the aryl bromides 12–15 with 4
and 8–10 was performed as shown in Scheme 4. Pd(OAc)2
(10 mol-%) and [(tBu3P)H]BF4 (30 mol-%) were added to a
stirred solution of the aryl bromides 12–15 (1 equiv.), boronic
acids or boronic acid pinacol esters 4 and 8–10 (2 equiv.), and
base (Na2CO3 or K2CO3) in THF/water (1:1). After a standard
work-up procedure and silica gel column chromatographic sep-
aration, the desired coupling products 16–21 were obtained in
moderate yields.
Knoevenagel condensation of aldehydes 16–21 with cyano-
acrylic acid tert-butyl ester (5) in the presence of piperidine
afforded the desired coupling compounds 22–27 in good-to-
excellent yields (Scheme 5). Subsequent removal of the tert-
butyl group by trifluoroacetic acid (TFA) afforded the desired
dyes 2a–2c and 3a–3c in good-to-excellent yields.
In terms of the EHOMO values for the Type I dyes, the EHOMO
values for 2a–2c containing the SEDs are less positive than that
of D4π4A2 without a SED. The EHOMO values become less posi-
tive in the order D4π4A2 > 2a > 2c > 2b (entries 1–3 vs. en-
try 8). In contrast, the EHOMO values for the Type II dyes 3a–3c
The absorption spectra and electrochemical properties of the
six synthesized dyes 2a–2c and 3a–3c were measured using
D3π4A2 and D4π4A2 without the SEDs as references (see Fig-
ures 2 and 3, Table 1).
In terms of the absorbance of Type I dyes, the introduction containing the SEDs are similar to, or more positive than, that
of the thiophene and 4-methoxybenzene SEDs led to a slight of D3π4A2 without a SED. In detail, the EHOMO values become
decrease in the visible (ca. 500 nm) absorbance, but a signifi- more positive in the order D3π4A2 ≈ 3c < 3a < 3b (entries 4–
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Figure 2. Absorption spectra of 2a–2c, 3a–3c, D3π4A2, and D4π4A2 in CH2Cl2.
Scheme 5. Knoevenagel condensation of aldehydes 16–21 with cyanoacrylic
acid tert-butyl ester (5) and subsequent acidic removal of the tert-butyl
group.
6 vs. entry 7). No significant change in the ELUMO values was
observed by introducing the SEDs (entries 1–3 vs. entry 8, en-
tries 4–6 vs. entry 7).
The HOMOs and LUMOs of all the synthesized dyes meet the
minimum requirement for a dye sensitizer in DSSCs, that is, the
values of the EHOMO and ELUMO are more positive than the
iodine/iodide redox potential [+0.4 V vs. a normal hydrogen
electrode (NHE)] and more negative than the conduction band
edge of TiO2 (–0.5 V vs. NHE), respectively. Photovoltaic proper-
ties were evaluated for the solar cells prepared by using the six
synthesized dyes with those prepared with D3π4A2, D4π4A2,
and D149 as references (Table 2).
Figure 3. Cyclic voltammograms of the synthesized dyes 2a–2c and 3a–3c
adsorbed on TiO2 mesoporous films on FTO substrates were recorded in
MeCN solution with LiClO4 (0.1
M) as electrolyte and with Pt wire and Ag/
Ag+ (0.01
M
of AgNO3 in MeCN) as counter and reference electrodes, respec-
tively. Before and after each measurement, the Ag/Ag+ reference electrode
was calibrated independently against the redox potential of ferrocene (FeIII/
FeII) on a Pt plate working electrode with LiClO4 (0.1
MeCN (referenced to +0.853 V vs. NHE).[34]
M) as electrolyte in
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Table 1. Photophysical and electrochemical properties of the six synthesized
dyes with D3π4A2 and D4π4A2 as references.
in a 33 mV increase in Voc in the case of Type II dyes (entry 4
vs. entry 7).
ε[b]
[M
Optical
E
HOMO [V][d] ELUMO [V][e]
[a]
–
Entry
Dye
λmax
In terms of the values of Jsc, for the Type I dyes, the introduc-
tion of the thiophene SED increases the Jsc (Table 2, entry 2 vs.
entry 8), whereas the introduction of the other SEDs did not
have a significant effect (entries 1 and 3 vs. entry 8). A different
tendency is observed for the Type II dyes. The introduction of
the diphenylethene and thiophene SEDs slightly increases the
[nm] 1 cm–1
]
edge[c] [nm]
(vs. NHE)
(vs. NHE)
1
2
3
4
5
6
7
8
2a
2b
402
489
389
501
383
498
402
516
390
520
384
520
377
519
373
494
30400
644
640
646
648
658
644
660
624
1.04
–0.89
23200
45900
42400
45200
46000
39400
30400
46300
41000
36000
34000
24600
31200
34200
48300
0.96
1.00
1.01
1.04
0.97
0.98
1.08
–0.97
–0.92
–0.90
–0.85
–0.95
–0.90
–0.91
2c
J
sc (entries 4 and 5 vs. entry 7), whereas the introduction of the
3a
4-methoxybenzene SED significantly decreases the Jsc (entry 6
vs. entry 7).
3b
In terms of the PCEs (values of η), for the Type I dyes, the
introduction of the thiophene SED improves the PCE (entry 2
vs. entry 8), whereas the introduction of the other SEDs de-
creases the PCE (entries 1 and 3 vs. entry 8). A different tend-
ency is observed for the Type II dyes. The introduction of the
diphenylethene SED improves the PCE (entry 4 vs. entry 7),
whereas the introduction of the thiophene SED has no effect
on the PCE (entry 5 vs. entry 7). On the other hand, the intro-
duction of the 4-methoxybenzene SED significantly decreases
the PCE (entry 6 vs. entry 7). Pleasingly, the DSSC prepared by
using the dye 2b, which contains the thiophene SED, exerts
a higher PCE (η = 4.62 0.02 %) than that prepared with our
previously reported best dye, D4π4A2 (entry 2 vs. entry 8).
3c
D3π4A2
D4π4A2
[a] Absorption maxima in CH2Cl2. [b] Molar absorption coefficients in CH2Cl2.
[c] The optical transmittance edge was defined by extrapolating the leading
edge of the optical transmission spectra of the dyes on TiO2 (see the Support-
ing Information) to the baseline. [d] EHOMO was determined by cyclic voltam-
metry. [e] The EHOMO–ELUMO gap was determined by the optical transmittance
edge, i.e., the EHOMO–ELUMO gap [eV] was calculated from 1240/optical edge.
E
LUMO was then calculated by the summation of the HOMO potential and the
E
HOMO–ELUMO gap.
The photocurrent–voltage curves and the IPCE spectra of the
six synthesized dyes, with D3π4A2, D4π4A2, and D149 as refer-
ences, are shown in Figure 4. As expected, the best dye 2b
exhibits a higher IPCE than our previously reported best dye,
D4π4A2, in the region 300–600 nm.
Table 2. Photovoltaic properties of the solar cells prepared by using the six
synthesized dyes with D3π4A2, D4π4A2, and D149 as references.
[a]
Entry
Dye
η
[a] [%]
FF[a]
Voc [mV]
Jsc [mA cm–1
]
[a]
1
2
3
4
5
6
7
8
9
2a
2b
2c
3a
3b
3c
3.85 0.20 0.517 0.023
4.62 0.02 0.571 0.005
4.24 0.07 0.567 0.028
4.38 0.02 0.586 0.014
4.23 0.07 0.575 0.016
2.96 0.10 0.657 0.017
723
722
714
751
703
695
718
758
737
9
7
6
1
7
6
0
1
9
10.3 0.14
11.2 0.05
10.5 0.57
10.0 0.33
10.5 0.35
6.5 0.36
9.4 0.28
10.1 0.26
7.97 0.14
D3π4A2 4.23 0.07 0.625 0.010
D4π4A2 4.45 0.14 0.582 0.027
D149
3.84 0.10 0.654 0.009
[a] Average values from two or three independent experiments.
In terms of the FF values, for the Type I dyes, the introduction
of the diphenylethene SED significantly decreases the FF (en-
try 1 vs. entry 8), whereas the introduction of the other SEDs
only slightly decreases the FF (entries 2 and 3 vs. entry 8). A
different tendency in the FF is observed for the Type II dyes.
The introduction of the diphenylethene and thiophene SEDs
led to a decrease in the FF values (entries 4 and 5 vs. entry 7),
whereas the introduction of the 4-methoxybenzene SED in-
creases the FF (entry 6 vs. entry 7).
In terms of the values of Voc, for the Type I dyes, the introduc-
tion of the SEDs decreases the value of Voc (Table 2, entries 1–
3 vs. entry 8). A different tendency is observed for the Type II
dyes. The introduction of the thiophene and 4-methoxy-
benzene SEDs decreases the value of Voc (Table 2, entries 5 and
6 vs. entry 7), whereas the introduction of the diphenylethene
SED increases the Voc (Table 2, entry 4 vs. entry 7). It is interest-
ing that the introduction of the diphenylethene SED results in
a 35 mV decrease in Voc in the case of the Type I dyes (entry 1
vs. entry 8), whereas the introduction of the same SED resulted
Figure 4. (a) Photocurrent–voltage curves obtained with DSSCs based on 2a–
2c, 3a–3c, D3π4A2, D4π4A2, and D149 under standard AM 1.5 solar condi-
tions and (b) incident photon-to-current conversion efficiency spectra for
DSSCs based on 2a–2c, 3a–3c, D3π4A2, D4π4A2, and D149.
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340.0714. The observed 1H NMR spectrum is consistent with that
of the reported spectrum.[27]
Conclusions
We have demonstrated a divergent synthesis of six dyes con-
taining our originally developed rigid and nonplanar donor
with three types of SEDs. Evaluation of the photophysical prop-
erties of the synthesized dyes revealed that the introduction of
the SEDs resulted in an increased absorbance in the 350–
450 nm region. The SEDs exert an influence on the electro-
9-(4-Bromophenyl)-6-iodo-2,3,4,4a,9,9a-hexahydro-1H-1,4-
methanocarbazole (1a): N-Iodosuccinimide (337 mg, 1.50 mmol)
was added to a stirred solution of 7 (280 mg, 0.823 mmol) in THF
(10 mL) at room temperature under Ar. After stirring at the same
temperature for 2 h, the reaction mixture was quenched with 10 %
aq. Na2S2O3 and extracted with Et2O. The extract was washed with
chemical and photovoltaic properties that differs according to brine, dried with sodium sulfate, filtered, and concentrated in vacuo.
The residue was purified by column chromatography on silica gel,
eluting with 10 % toluene in hexane to afford 9-(4-bromophenyl)-
6-iodo-2,3,4,4a,9,9a-hexahydro-1H-1,4-methanocarbazole (1a;
232 mg, 0.50 mmol, 61 %) as a white solid, m.p. 140–142 °C. 1H
NMR (400 MHz, CDCl3): δ = 7.36 (dt, J = 8.7, 2.4 Hz, 2 H), 7.30 (d,
J = 2.0 Hz, 1 H), 7.22 (dd, J = 8.7, 1.9 Hz, 1 H), 7.07 (dt, J = 9.2,
2.4 Hz, 2 H), 6.62 (d, J = 8.7 Hz, 1 H), 4.12 (d, J = 8.2 Hz, 1 H), 3.19
(d, J = 8.2 Hz, 1 H), 2.39 (d, J = 2.9 Hz, 1 H), 2.28 (s, 1 H), 1.60–1.46
(m, 2 H), 1.40 (d, J = 10.2 Hz, 1 H), 1.38–1.30 (m, 1 H), 1.28–1.16 (m,
1 H), 1.08 (d, J = 10.2 Hz, 1 H) ppm. 13C NMR (100 MHz, CDCl3): δ =
the structure of the SED (thiophene, 4-methoxybenzene, or di-
phenylethene) and their positions (Type I or Type II). The values
of EHOMO for the Type I dyes become less positive on the intro-
duction of the SEDs, whereas the values of EHOMO for the Type II
dyes become more positive on the introduction of the SEDs.
The introduction of the thiophene SED to the Type I dye re-
sulted in an increase in Jsc. The DSSC prepared by using the
dye 2b has a PCE (η = 4.62 0.02 %) higher than that of our
previously reported best dye, D4π4A2. The dye 2b exhibits an
IPCE that is also higher than that of D4π4A2 in the region 300– 148.1, 142.0, 136.6, 135.9, 133.7, 132.1, 121.1, 114.1, 110.0, 79.1, 71.3,
50.0, 43.4, 40.8, 32.3, 28.3, 25.1 ppm. FTIR (neat): ν = 2955, 2870,
600 nm.
˜
1582, 1491, 1474, 1413, 1370, 1327, 1301, 1252, 1218, 1113, 1065,
1003, 799, 770, 665, 508 cm–1. HRMS (ESI-TOF): calcd. for C19H18NBrI
465.9667 [M + H]+; found 465.9691.
Experimental Section
General Procedure for the First Suzuki–Miyaura Coupling Reac-
tion in the Synthesis of 12–15: Base, Pd(OAc)2, [(tBu3P)H]BF4, and
arylboronic acid or arylboronic acid pinacol ester 8–11 were added
to a stirred solution of aryl iodide 1a in solvent at room temperature
under Ar. After stirring at the given temperature for the specified
General: NMR spectra were recorded with a JEOL Model EX-270
(270 MHz for 1H, 67.8 MHz for 13C) or ECP-400 (400 MHz for 1H,
100 MHz for 13C) spectrometer in the indicated solvent. Chemical
shifts are reported in ppm relative to the signal of tetramethylsilane
1
(δ = 0 ppm for H) as internal reference for solutions in CDCl3. The
time, the reaction mixture was quenched with 1
M HCl and ex-
NMR spectroscopic data are reported as follows: chloroform (δ =
7.26 ppm for 1H), [D6]DMSO (δ = 2.50 ppm) or [D]chloroform (δ =
77.1 ppm for 13C), [D6]DMSO (δ = 49.8 ppm). Multiplicities are re-
ported according to the following abbreviations: s = singlet, d =
doublet, t = triplet, q = quartet, m = multiplet, br. = broad. Coupling
tracted with Et2O. The extract was washed with brine, dried with
sodium sulfate, filtered, and concentrated in vacuo. The residue was
purified by column chromatography to afford the products 12–15.
9-(4-Bromophenyl)-6-(2,2-diphenylvinyl)-2,3,4,4a,9,9a-hexa-
constants (J) are given in Hz. IR spectra were recorded with a Per- hydro-1H-1,4-methanocarbazole (12): From aryl iodide 1a
kin–Elmer Spectrum One FT-IR spectrophotometer. Only the strong (100 mg, 0.215 mmol) in THF (2 mL), 1 aq. Na2CO3 (0.323 mL,
and/or structurally important absorptions are reported. All the reac- 0.323 mmol), Pd(OAc)2 (4.8 mg, 0.022 mmol), [(tBu3P)H]BF4
M
tions were monitored by TLC carried out on 0.2 mm E. Merck silica
gel plates (60F-254) with UV light, visualized by p-anisaldehyde so-
lution, ceric sulfate, or 10 % ethanolic phosphomolybdic acid. Merck
(18.7 mg, 0.0645 mmol), arylboronic acid pinacol ester 8 (79.0 mg,
0.258 mmol) at room temp. for 15 h. Column chromatography on
silica gel, eluting with 5 % ethyl acetate in hexane, gave product
silica gel 60 (0.063–0.200 mm) was used for column chromatogra- 12 (66.3 mg, 0.128 mmol, 60 %) as a yellow solid, m.p. 60–63 °C. 1H
phy. ESI TOF mass spectra were recorded with a Waters LCT
NMR (400 MHz, CDCl3): δ = 7.35 (d, J = 8.7 Hz, 2 H), 7.38–7.14 (m,
PremierTM XE spectrometer. HRMS (ESI-TOF) were calibrated with 10 H), 7.10 (d, J = 8.7 Hz, 2 H), 6.87 (s, 1 H), 6.75 (d, J = 8.2 Hz, 1
leucine enkephalin (SIGMA) as internal standard.
H), 6.79 (d, J = 8.2 Hz, 1 H), 6.65 (s, 1 H), 4.11 (d, J = 8.2 Hz, 1 H),
3.06 (d, J = 8.2 Hz, 1 H), 2.39 (s, 1 H), 2.03 (s, 1 H), 1.65–1.55 (m, 2
H), 1.36 (d, J = 10.1 Hz, 1 H), 1.32–1.28 (m, 1 H), 1.28–1.20 (m, 1 H),
1.03 (d, J = 10.1 Hz, 1 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 146.8,
143.7, 142.1, 139.0, 133.3, 131.9, 130.5, 129.3, 128.6, 128.2, 128.1,
127.2, 127.1, 126.8, 126.2, 120.6, 113.3, 107.4, 71.0, 49.9, 43.0, 40.6,
9-(4-Bromophenyl)-2,3,4,4a,9,9a-hexahydro-1H-1,4-methano-
carbazole (7): [PdCl2(dppf)] (115 mg, 0.157 mmol) was added to a
stirred solution of 6 (578 mg, 3.14 mmol), 1-bromo-4-iodobenzene
(1.07 g, 3.77 mmol), and KOtBu (529 mg, 4.71 mmol) in toluene
(10 mL) at room temperature under Ar. After stirring at 100 °C for
32.1, 28.2, 25.1 ppm. FTIR (neat): ν = 2955, 1677, 1588, 1493, 1445,
˜
15 h, the reaction mixture was diluted with Et2O and 1
M HCl and
1376, 1328, 1260, 1216, 1181, 1108, 1074, 900, 809, 759, 698,
499 cm–1. HRMS (ESI-TOF): calcd. for C33H29NBr 518.1483 [M + H]+;
found 518.1512.
extracted with Et2O. The extract was washed with brine, dried with
sodium sulfate, filtered, and concentrated in vacuo. The residue was
purified by column chromatography on silica gel, eluting with 20 %
toluene in hexane to afford 9-(4-bromophenyl)-2,3,4,4a,9,9a-hexa- 9-(4-Bromophenyl)-6-(thiophen-2-yl)-2,3,4,4a,9,9a-hexahydro-
hydro-1H-1,4-methanocarbazole (7; 864 mg, 2.53 mmol, 81 %) as a
white solid. H NMR (400 MHz, CDCl3): δ = 7.37 (dt, J = 9.2, 2.9 Hz,
1H-1,4-methanocarbazole (13): Aryl iodide 1a (50 mg,
0.107 mmol), THF (1 mL), water (1 mL), K2CO3 (34.5 mg, 0.25 mmol),
Pd(OAc)2 (2.0 mg, 0.0089 mmol), [(tBu3P)H]BF4 (10.0 mg,
0.034 mmol), arylboronic acid 9 (20 mg, 0.16 mmol), 70 °C, 15 h.
Column chromatography on silica gel, eluting with 10 % ethyl ace-
tate in hexane, gave product 13 (32.0 mg, 0.076 mmol, 71 %) as a
white solid, m.p. 153–155 °C. 1H NMR (400 MHz, CDCl3): δ = 7.41
(dt, J = 8.7, 2.5 Hz, 2 H), 7.34 (s, 1 H), 7.29 (dd, J = 8.2, 1.9 Hz, 1 H),
1
2 H), 7.15 (dt, J = 9.2, 2.9 Hz, 2 H), 7.08 (d, J = 7.2 Hz, 1 H), 7.01 (t,
J = 7.2 Hz, 1 H), 6.90 (d, J = 7.2 Hz, 1 H), 6.70 (t, J = 7.2 Hz, 1 H),
4.15 (d, J = 8.2 Hz, 1 H), 3.27 (d, J = 8.2 Hz, 1 H), 2.45 (d, J = 3.4 Hz,
1 H), 2.33 (s, 1 H), 1.64–1.50 (m, 2 H), 1.44 (d, J = 10.2 Hz, 1 H), 1.42–
1.34 (m, 1 H), 1.30–1.19 (m, 1 H), 1.08 (d, J = 10.2 Hz, 1 H) ppm.
HRMS (ESI-TOF): calcd. for C19H19NBr 340.0701 [M + H]+; found
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7.20–7.14 (m, 2 H), 7.17 (dt, J = 8.7, 2.5 Hz, 2 H), 7.02 (t, J = 4.3 Hz, tography on silica gel, eluting with 10 % ethyl acetate in hexane,
1 H), 6.89 (d, J = 8.2 Hz, 1 H), 4.23 (d, J = 8.2 Hz, 1 H), 3.32 (d, J = gave product 16 (29.8 mg, 0.0348 mmol, 42 %) as a red solid and
1
8.2 Hz, 1 H), 2.47 (d, J = 3.4 Hz, 1 H), 2.40 (s, 1 H), 1.65–1.55 (m, 2
H), 1.48 (d, J = 10.2 Hz, 1 H), 1.45–1.38 (m, 1 H), 1.30–1.22 (m, 1 H),
1.13 (d, J = 10.2 Hz, 1 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 147.7,
substrate 12 (11.7 mg, 0.226 mmol, 27 %), m.p. 53–55 °C. H NMR
(400 MHz, CDCl3): δ = 9.94 (s, 1 H), 7.88 (s, 1 H), 7.52 (d, J = 8.7 Hz,
2 H), 7.40–7.22 (m, 11 H), 7.25 (d, J = 8.7 Hz, 2 H), 7.09 (s, 1 H), 6.81
145.1, 142.3, 134.5, 132.1, 127.8, 125.7, 125.3, 122.9, 122.8, 121.1, (d, J = 5.3 Hz, 1 H), 6.68 (s, 1 H), 4.23 (d, J = 7.8 Hz, 1 H), 3.09 (d,
120.8, 113.5, 108.2, 71.3, 50.1, 43.4, 40.8, 32.3, 28.4, 25.2 ppm. FTIR
J = 7.8 Hz, 1 H), 2.80 (t, J = 6.7 Hz, 2 H), 2.48 (s, 1 H), 2.08 (s, 1 H),
1.74–1.65 (m, 2 H), 1.61–1.52 (m, 2 H), 1.40 (d, J = 9.2 Hz, 1 H), 1.35–
(neat): ν = 2956, 2870, 1611, 1584, 1492, 1446, 1427, 1374, 1328,
˜
1301, 1257, 1216, 1111, 1076, 1002, 808, 758, 692 cm–1. HRMS (ESI- 1.20 (m, 20 H), 1.08 (d, J = 9.2 Hz, 1 H), 0.87 (t, J = 6.3 Hz, 3 H) ppm.
TOF): calcd. for C23H21BrNS 422.0578 [M + H]+; found 422.0533.
13C NMR (100 MHz, CDCl3): δ = 183.0, 146.7, 146.3, 144.1, 143.7,
142.9, 142.5, 141.0, 139.1, 138.2, 133.6, 130.5, 129.4, 128.9, 128.6,
128.1, 127.2, 127.1, 126.9, 126.4, 126.3, 126.2, 125.2, 118.8, 117.4,
107.9, 70.8, 50.0, 49.9, 43.0, 40.7, 32.2, 31.9, 30.5, 29.7, 29.6, 29.5,
9-(4-Bromophenyl)-6-(4-methoxyphenyl)-2,3,4,4a,9,9a-hexa-
hydro-1H-1,4-methanocarbazole (14): Aryl iodide 1a (100 mg,
0.215 mmol), THF (3 mL), 1
M aq. Na2CO3 (0.428 mL, 0.428 mmol),
29.4, 29.3, 28.6, 28.3, 25.2, 22.6, 14.1 ppm. FTIR (neat): ν = 2923,
˜
Pd(OAc)2 (2.4 mg, 0.011 mmol), [(tBu3P)H]BF4 (9.2 mg, 0.032 mmol),
arylboronic acid 10 (39.0 mg, 0.257 mmol), 60 °C, 15 h. Column
chromatography on silica gel, eluting with 10 % ethyl acetate in
hexane, gave product 14 (65.0 mg, 0.146 mmol, 68 %) as a yellow
2852, 1664, 1597, 1493, 1408, 1377, 1228, 1124, 811, 761,
698 cm–1. HRMS (ESI-TOF): calcd. for C56H58NOS3 856.3681 [M + H]+;
found 856.3647.
1
oil. H NMR (400 MHz, CDCl3): δ = 7.47 (d, J = 6.8 Hz, 2 H), 7.40 (d,
Aldehyde 17: Aryl bromide 13 (20.0 mg, 0.0474 mmol), THF (1 mL),
J = 6.7 Hz, 2 H), 7.30 (s, 1 H), 7.22 (dd, J = 8.7, 1.9 Hz, 1 H), 7.18 (d,
J = 6.7 Hz, 2 H), 6.96 (d, J = 8.7 Hz, 1 H), 6.93 (d, J = 6.8 Hz, 1 H),
4.23 (d, J = 7.7 Hz, 1 H), 3.34 (d, J = 7.7 Hz, 1 H), 2.48 (s, 1 H), 2.40
(s, 1 H), 1.61–1.55 (m, 2 H), 1.52 (d, J = 10.1 Hz, 1 H), 1.45–1.38 (m,
1 H), 1.30–1.22 (m, 1 H), 1.12 (d, J = 10.1 Hz, 1 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 158.4, 147.0, 142.6, 134.4, 133.9, 132.0, 127.3,
125.6, 123.3, 120.5, 114.1, 113.1, 108.4, 71.2, 55.3, 50.3, 43.4, 40.8,
1
M aq. Na2CO3 (0.095 mL, 0.095 mmol), Pd(OAc)2 (1.1 mg,
0.0047 mmol), [(tBu3P)H]BF4 (4.1 mg, 0.014 mmol), arylboronic acid
pinacol ester 4 (51.6 mg, 0.0947 mmol), 70 °C, 15 h. Column chro-
matography on silica gel, eluting with 10 % ethyl acetate in hexane,
gave product 17 (15.7 mg, 0.0206 mmol, 44 %) as an orange solid,
1
m.p. 72–76 °C. H NMR (400 MHz, CDCl3): δ = 9.92 (s, 1 H), 7.86 (s,
1 H), 7.55 (d, J = 8.7 Hz, 2 H), 7.35 (s, 1 H), 7.32–7.28 (m, 3 H), 7.29
(d, J = 8.7 Hz, 2 H), 7.18–7.15 (m, 2 H), 7.10 (s, 1 H), 7.03 (t, J =
4.8 Hz, 1 H), 7.00 (d, J = 8.2 Hz, 1 H), 4.29 (d, J = 8.2 Hz, 1 H), 3.33
(d, J = 8.2 Hz, 1 H), 2.80 (t, J = 6.7 Hz, 2 H), 2.53 (s, 1 H), 2.41 (s, 1
H), 1.73–1.68 (m, 2 H), 1.63–1.57 (m, 2 H), 1.50 (d, J = 10.2 Hz, 1 H),
1.45–1.20 (m, 20 H), 1.13 (d, J = 10.2 Hz, 1 H), 0.87 (t, J = 6.3 Hz, 3
H) ppm. 13C NMR (100 MHz, CDCl3): δ = 182.9, 147.5, 146.3, 145.3,
145.1, 144.3, 144.0, 143.0, 142.5, 138.9, 128.2, 127.8, 126.4, 125.7,
125.3, 122.9, 122.8, 121.1, 118.9, 117.3, 108.5, 71.1, 50.1, 43.4, 40.8,
32.3, 31.9, 30.5, 29.7, 29.6, 29.5, 29.4, 29.3, 28.3, 25.2, 22.6, 14.1 ppm.
32.3, 28.4, 25.2 ppm. FTIR (neat): ν = 2956, 2079, 1641, 1585, 1491,
˜
1370, 1328, 1298, 1246, 1179, 1112, 1042, 802, 755 cm–1. HRMS (ESI-
TOF): calcd. for C26H25ONBr 446.1120 [M + H]+; found 446.1103.
Aldehyde 15: Aryl iodide 1a (200 mg, 0.429 mmol), THF (6 mL), 1
M
aq. Na2CO3 (0.856 mL, 0.856 mmol), Pd(OAc)2 (4.8 mg, 0.022 mmol),
[(tBu3P)H]BF4 (18.3 mg, 0.063 mmol), arylboronic acid pinacol ester
11 (280 mg, 0.515 mmol), 60 °C, 10 h. Column chromatography on
silica gel, eluting with 10 % ethyl acetate in hexane, gave product
1
15 (220 mg, 0.291 mmol, 67 %) as a red solid, m.p. 108–111 °C. H
FTIR (neat): ν = 2923, 2851, 1660, 1600, 1485, 1408, 1377, 1328,
˜
NMR (400 MHz, CDCl3): δ = 9.93 (s, 1 H), 7.87 (s, 1 H), 7.42 (d, J =
8.7 Hz, 2 H), 7.33 (s, 1 H), 7.29 (s, 1 H), 7.27 (dd, J = 8.2, 1.9 Hz, 2
H), 7.18 (d, J = 8.7 Hz, 2 H), 7.03 (s, 1 H), 6.88 (d, J = 8.2 Hz, 1 H),
4.25 (d, J = 8.2 Hz, 1 H), 3.32 (d, J = 8.2 Hz, 1 H), 2.79 (t, J = 6.7 Hz,
2 H), 2.45 (s, 1 H), 2.41 (s, 1 H), 1.74–1.67 (m, 2 H), 1.64–1.55 (m, 2
H), 1.48 (d, J = 10.1 Hz, 1 H), 1.45–1.20 (m, 20 H), 1.13 (d, J = 10.1 Hz,
1 H), 0.87 (t, J = 6.3 Hz, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ =
182.9, 148.3, 146.4, 145.6, 144.8, 144.1, 142.4, 141.9, 138.0, 134.5,
132.1, 128.9, 127.3, 125.2, 124.6, 124.4, 122.4, 121.1, 117.0, 114.0,
108.0, 71.3, 50.0, 43.4, 40.7, 32.2, 32.1, 31.9, 30.4, 29.7, 29.6, 29.5,
1257, 1227, 1124, 810, 756, 691 cm–1. HRMS (ESI-TOF): calcd. for
C
46H50NOS4 760.2775 [M + H]+; found 760.2741.
Aldehyde 18: Aryl bromide 14 (42.0 mg, 0.0941 mmol), THF (2 mL),
aq. Na2CO3 (0.188 mL, 0.188 mmol), Pd(OAc)2 (2.1 mg,
1
M
0.0094 mmol), [(tBu3P)H]BF4 (8.2 mg, 0.028 mmol), arylboronic acid
pinacol ester 4 (102 mg, 0.188 mmol), 70 °C, 10 h. Column chroma-
tography on silica gel, eluting with 10 % ethyl acetate in hexane,
gave product 18 (25.2 mg, 0.0321 mmol, 34 %) as a red solid, m.p.
1
56–60 °C. H NMR (400 MHz, CDCl3): δ = 9.92 (s, 1 H), 7.85 (s, 1 H),
29.4, 29.3, 28.3, 25.1, 22.6, 14.1 ppm. FTIR (neat): ν = 2924, 2853,
˜
7.53 (d, J = 7.2 Hz, 2 H), 7.48 (d, J = 7.2 Hz, 2 H), 7.34–7.28 (m, 3 H),
7.26 (m, 1 H), 7.24 (s, 1 H), 7.09 (s, 1 H), 7.05 (d, J = 5.3 Hz, 1 H),
6.94 (d, J = 7.3 Hz, 2 H), 4.28 (d, J = 7.8 Hz, 1 H), 3.83 (s, 3 H), 3.34
(d, J = 7.8 Hz, 1 H), 2.80 (t, J = 6.7 Hz, 2 H), 2.55 (s, 1 H), 2.41 (s, 1
H), 1.69 (m, 2 H), 1.61–1.55 (m, 2 H), 1.50 (d, J = 9.2 Hz, 1 H), 1.45–
1.20 (m, 20 H), 1.13 (d, J = 9.2 Hz, 1 H), 0.87 (t, J = 6.3 Hz, 3 H) ppm.
13C NMR (100 MHz, CDCl3): δ = 183.0, 158.4, 146.8, 146.3, 145.3,
144.3, 144.2, 142.4, 138.1, 134.6, 133.8, 132.0, 128.9, 128.1, 127.3,
126.4, 126.0, 125.6, 125.1, 123.3, 118.5, 117.9, 117.3, 114.1, 108.8,
71.0, 55.3, 50.3, 43.4, 40.8, 32.3, 31.9, 30.4, 29.7, 29.6, 29.5, 29.4, 29.3,
1661, 1611, 1585, 1493, 1408, 1369, 1327, 1258, 1228, 1171, 1124,
809, 756 cm–1. HRMS (ESI-TOF): calcd. for C42H47BrNOS3 756.2003
[M + H]+; found 756.1969.
General Procedure for the Second Suzuki–Miyaura Coupling Re-
action for the Synthesis of 16–21: Base, Pd(OAc)2, [(tBu3P)H]BF4,
and arylboronic acid or arylboronic acid pinacol ester 4 or 8–10
were added to a stirred solution of aryl bromide 12–15 in the given
solvent at room temperature under Ar. After stirring at the given
temperature for the specified time, the reaction mixture was
28.4, 25.2, 22.6, 14.0 ppm. FTIR (neat): ν = 2923, 2852, 2082, 1659,
quenched with 1
M
HCl and extracted with Et2O. The extract was
˜
1482, 1408, 1372, 1302, 1227, 1177, 1124, 803, 697 cm–1. HRMS (ESI-
TOF): calcd. for C49H54NO2S3 784.3317 [M + H]+; found 784.3272.
washed with brine, dried with sodium sulfate, filtered, and concen-
trated in vacuo. The residue was purified by column chromatogra-
phy to afford products 16–21.
Aldehyde 19: Aryl bromide 15 (56.7 mg, 0.0749 mmol), toluene
(2 mL), water (0.5 mL), Na2CO3 (50 mg, 0.472 mmol), Pd(OAc)2
(3.0 mg, 0.0134 mmol), [(tBu3P)H]BF4 (10.0 mg, 0.0345 mmol), aryl-
boronic acid pinacol ester 8 (77.9 mg, 0.254 mmol), 110 °C, 15 h.
Aldehyde 16: Aryl bromide 12 (42.8 mg, 0.0827 mmol), toluene
(2 mL), 1
M aq. Na2CO3 (0.500 mL, 0.500 mmol), Pd(OAc)2 (1.8 mg,
0.0083 mmol), [(tBu3P)H]BF4 (7.2 mg, 0.025 mmol), arylboronic acid
pinacol ester 4 (100 mg, 0.169 mmol), 100 °C, 15 h. Column chroma- Column chromatography on silica gel, eluting with 10 % ethyl
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acetate in hexane, gave product 19 (32.3 mg, 0.0377 mmol, 50 %) same temperature for 6 h, the reaction mixture was diluted with
as a red solid, m.p. 71–75 °C. 1H NMR (400 MHz, CDCl3): δ = 9.92 (s,
1 H), 7.85 (s, 1 H), 7.42–7.23 (m, 13 H), 7.06 (d, J = 9.2 Hz, 2 H), 7.02
(s, 1 H), 6.98 (d, J = 9.2 Hz, 1 H), 6.92 (s, 1 H), 6.90 (d, J = 4.8 Hz, 1
H), 4.22 (d, J = 8.2 Hz, 1 H), 3.28 (d, J = 8.2 Hz, 1 H), 2.79 (t, J =
6.7 Hz, 2 H), 2.46 (s, 1 H), 2.38 (s, 1 H), 1.74–1.67 (m, 2 H), 1.62–1.55
Et2O, quenched with water, and extracted with Et2O. The extract
was washed with brine, dried with sodium sulfate, filtered, and con-
centrated in vacuo. The residue was purified by column chromatog-
raphy to afford protected dyes 22–27. Trifluoroacetic acid (0.70 mL)
was added to a stirred solution of the protected dyes 22–27 in
(m, 2 H), 1.46 (d, J = 10.1 Hz, 1 H), 1.45–1.20 (m, 20 H), 1.13 (d, J = dichloromethane (3.0 mL) at room temperature under argon. After
10.1 Hz, 1 H), 0.87 (t, J = 6.3 Hz, 3 H) ppm. 13C NMR (100 MHz, stirring at the same temperature for 5 h, the mixture was concen-
CDCl3): δ = 182.9, 148.3, 146.4, 145.6, 145.0, 144.1, 143.5, 142.4,
trated in vacuo. The residue was purified by column chromatogra-
141.4, 140.7, 138.0, 134.6, 130.7, 130.4, 130.3, 128.9, 128.7, 128.1, phy on silica gel, eluting with 0.01 % acetic acid in ethyl acetate to
127.5, 127.3, 127.1, 125.1, 124.3, 122.3, 118.2, 117.0, 108.4, 71.0, 49.9, afford the dyes 2a–2c and 3a–3c.
43.4, 40.8, 32.3, 31.9, 30.4, 29.7, 29.6, 29.5, 29.4, 29.3, 28.3, 25.2, 22.6,
Dye 2a: Knoevenagel condensation reaction of aldehyde 16
(13.7 mg, 0.016 mmol), THF (1 mL), and tert-butyl cyanoacetate
(4.6 μL, 0.032 mmol). Column chromatography on silica gel, eluting
14.1 ppm. FTIR (neat): ν = 2924, 2853, 1661, 1597, 1510, 1407, 1372,
˜
1328, 1258, 1228, 1124, 808, 759, 698 cm–1. HRMS (ESI-TOF): calcd.
for C56H58NOS3 856.3681 [M + H]+; found 856.3664.
with 10 % ethyl acetate in hexane, gave protected dye 22 (12.5 mg,
Aldehyde 20: Aryl bromide 15 (40.0 mg, 0.0528 mmol), THF (1 mL),
aq. Na2CO3 (0.106 mL, 0.106 mmol), Pd(OAc)2 (1.2 mg,
0.0053 mmol), [(tBu3P)H]BF4 (4.6 mg, 0.016 mmol), arylboronic acid
0.0128 mmol, 80 %) as a red amorphous solid. 1H NMR (400 MHz,
CDCl3): δ = 8.23 (s, 1 H), 7.91 (s, 1 H), 7.52 (d, J = 8.7 Hz, 2 H), 7.40–
7.22 (m, 11 H), 7.26 (d, J = 8.7 Hz, 2 H), 7.09 (s, 1 H), 6.90 (s, 1 H),
1
M
9 (13.6 mg, 0.106 mmol), 70 °C, 20 h. Column chromatography on 6.81 (d, J = 5.3 Hz, 1 H), 6.68 (s, 1 H), 4.23 (d, J = 7.8 Hz, 1 H), 3.10
silica gel, eluting with 10 % ethyl acetate in hexane, gave product
20 (11.6 mg, 0.0152 mmol, 29 %) as a red solid and substrate 15
(24.0 mg, 0.0317 mmol, 60 %), m.p. >300 °C. 1H NMR (400 MHz,
CDCl3): δ = 9.93 (s, 1 H), 7.87 (s, 1 H), 7.57 (d, J = 8.7 Hz, 2 H), 7.34
(s, 1 H), 7.30 (d, J = 8.7 Hz, 2 H), 7.30 (s, 1 H), 7.29 (m, 1 H), 7.25 (s,
1 H), 7.23 (d, J = 5.3 Hz, 1 H), 7.06 (dd, J = 5.3, 3.9 Hz, 1 H), 7.04 (s,
(d, J = 7.8 Hz, 1 H), 2.80 (t, J = 6.7 Hz, 2 H), 2.48 (s, 1 H), 2.08 (s, 1
H), 1.74–1.65 (m, 2 H), 1.61–1.52 (m, 2 H), 1.40 (d, J = 9.2 Hz, 1 H),
1.35–1.20 (m, 20 H), 1.08 (d, J = 9.2 Hz, 1 H), 0.87 (t, J = 6.3 Hz, 3
H) ppm. 13C NMR (100 MHz, CDCl3): δ = 161.8, 146.9, 146.7, 146.0,
145.4, 144.2, 143.7, 142.9, 142.7, 141.0, 139.1, 138.9, 136.8, 133.6,
130.5, 129.4, 128.7, 128.6, 128.2, 128.1, 127.2, 127.1, 127.2, 127.1,
1 H), 6.95 (d, J = 8.2 Hz, 1 H), 4.33 (d, J = 8.2 Hz, 1 H), 3.32 (d, J = 126.9, 126.4, 126.2, 125.3, 118.8, 116.9, 116.4, 107.9, 99.3, 83.4, 70.8,
8.2 Hz, 1 H), 2.80 (t, J = 6.7 Hz, 2 H), 2.52 (s, 1 H), 2.42 (s, 1 H), 1.74–
1.67 (m, 2 H), 1.64–1.55 (m, 2 H), 1.53 (d, J = 10.1 Hz, 1 H), 1.45–
49.9, 43.0, 40.7, 32.2, 31.9, 30.5, 29.8, 29.6, 29.5, 29.4, 29.3, 28.3, 28.0,
25.2, 22.6, 14.1 ppm. FTIR (neat): ν = 2928, 2856, 2215, 1712, 1582,
˜
1.20 (m, 20 H), 1.13 (d, J = 10.1 Hz, 1 H), 0.87 (t, J = 6.3 Hz, 3 H) ppm. 1512, 1485, 1454, 1408, 1369, 1255, 1153, 840, 754, 703 cm–1. HRMS
13C NMR (100 MHz, CDCl3): δ = 182.9, 148.5, 146.4, 145.6, 145.0,
(ESI-TOF): calcd. for C63H67N2O2S3 979.4365 [M + H]+; found
144.3, 144.1, 142.4, 142.1, 138.0, 134.6, 128.7, 128.0, 127.9, 127.2, 979.4331.
126.7, 125.2, 124.4, 123.9, 122.4, 122.1, 119.6, 117.0, 108.1, 71.2, 50.0,
Removal of tert-butyl group gave dye 2a: Yield 90 %; dark-red solid,
43.5, 40.8, 32.3, 31.9, 30.5, 29.8, 29.6, 29.5, 29.4, 29.3, 28.4, 25.2, 22.6,
m.p. 165–170 °C. 1H NMR (400 MHz, [D6]DMSO): δ = 8.49 (s, 1 H),
8.23 (s, 1 H), 7.69 (s, 1 H), 7.56 (d, J = 8.7 Hz, 2 H), 7.42–7.35 (m, 2
H), 7.35–7.20 (m, 9 H), 7.16 (d, J = 8.6 Hz, 2 H), 6.96 (s, 1 H), 6.78 (s,
2 H), 6.60 (s, 1 H), 4.30 (d, J = 8.3 Hz, 1 H), 3.01 (d, J = 8.2 Hz, 1 H),
2.76 (t, J = 6.7 Hz, 2 H), 2.32 (s, 1 H), 1.94 (s, 1 H), 1.70–1.58 (m, 2
H), 1.55–1.40 (m, 2 H), 1.53 (d, J = 9.2 Hz, 1 H), 1.35–1.20 (m, 20 H),
0.99 (d, J = 9.2 Hz, 1 H), 0.80 (t, J = 6.3 Hz, 3 H) ppm. 13C NMR
14.1 ppm. FTIR (neat): ν = 2924, 2852, 1660, 1601, 1535, 1501, 1407,
˜
1372, 1258, 1228, 1124, 810, 692 cm–1. HRMS (ESI-TOF): calcd. for
C46H50NOS4 760.2775 [M + H]+; found 760.2787.
Aldehyde 21: Aryl bromide 15 (30.0 mg, 0.0396 mmol), THF (1 mL),
1
M
aq. Na2CO3 (0.106 mL, 0.106 mmol), Pd(OAc)2 (1.2 mg,
0.0053 mmol), [(tBu3P)H]BF4 (4.6 mg, 0.016 mmol), arylboronic acid
10 (16.1 mg, 0.106 mmol), 70 °C, 20 h. Column chromatography on (67.8 MHz, [D6]DMSO): δ = 146.6, 146.4, 146.0, 143.6, 143.0, 142.8,
silica gel, eluting with 10 % ethyl acetate in hexane, gave product
21 (13.8 mg, 0.0176 mmol, 44 %) as a red solid and substrate 15
(24.0 mg, 0.0317 mmol, 60 %), m.p. >300 °C. 1H NMR (400 MHz,
CDCl3): δ = 9.93 (s, 1 H), 7.87 (s, 1 H), 7.57 (d, J = 8.7 Hz, 2 H), 7.34
(s, 1 H), 7.30 (d, J = 8.7 Hz, 2 H), 7.30 (s, 1 H), 7.29 (m, 1 H), 7.25 (s,
1 H), 7.23 (d, J = 5.3 Hz, 1 H), 7.06 (dd, J = 5.3, 3.9 Hz, 1 H), 7.04 (s,
1 H), 6.95 (d, J = 8.2 Hz, 1 H), 4.33 (d, J = 8.2 Hz, 1 H), 3.32 (d, J =
8.2 Hz, 1 H), 2.80 (t, J = 6.7 Hz, 2 H), 2.52 (s, 1 H), 2.42 (s, 1 H), 1.74–
1.67 (m, 2 H), 1.64–1.55 (m, 2 H), 1.53 (d, J = 10.1 Hz, 1 H), 1.45–
1.20 (m, 20 H), 1.13 (d, J = 10.1 Hz, 1 H), 0.87 (t, J = 6.3 Hz, 3 H) ppm.
13C NMR (100 MHz, CDCl3): δ = 182.9, 148.5, 146.4, 145.6, 145.0,
144.3, 144.1, 142.4, 142.1, 138.0, 134.6, 128.7, 128.0, 127.9, 127.2,
126.7, 125.2, 124.4, 123.9, 122.4, 122.1, 119.6, 117.0, 108.1, 71.2, 50.0,
43.5, 40.8, 32.3, 31.9, 30.5, 29.8, 29.6, 29.5, 29.4, 29.3, 28.4, 25.2, 22.6,
142.4, 142.0, 140.5, 137.9, 137.8, 137.0, 133.2, 131.5, 129.8, 129.4,
128.9, 128.2, 128.0, 127.7, 126.8, 126.5, 126.1, 125.9, 125.7, 125.3,
118.4, 118.1, 116.7, 107.3, 69.6, 48.9, 42.6, 31.6, 31.2, 29.6, 28.9, 28.8,
28.6, 27.6, 24.5, 22.0, 13.8 ppm. FTIR (neat): ν = 2923, 1675, 1570,
˜
1481, 1401, 1259, 758 cm–1. HRMS (ESI-TOF): calcd. for C59H59N2O2S3
923.3739 [M + H]+; found 923.3761.
Dye 2b: Knoevenagel condensation reaction of aldehyde 17
(23.0 mg, 0.0303 mmol), THF (3 mL), and tert-butyl cyanoacetate
(6.9 μL, 0.048 mmol). Column chromatography on silica gel, eluting
with chloroform, gave protected dye 23 (17.6 mg, 0.0199 mmol,
1
66 %) as a red solid, m.p. 86–89 °C. H NMR (400 MHz, CDCl3): δ =
8.22 (s, 1 H), 7.88 (s, 1 H), 7.54 (d, J = 8.7 Hz, 2 H), 7.35 (s, 1 H),
7.34–7.28 (m, 3 H), 7.30 (d, J = 8.7 Hz, 2 H), 7.18–7.15 (m, 2 H), 7.10
(s, 1 H), 7.03 (t, J = 4.8 Hz, 1 H), 7.00 (d, J = 8.2 Hz, 1 H), 4.29 (d, J =
8.2 Hz, 1 H), 3.33 (d, J = 8.2 Hz, 1 H), 2.81 (t, J = 6.7 Hz, 2 H), 2.53
(s, 1 H), 2.41 (s, 1 H), 1.73–1.68 (m, 2 H), 1.63–1.57 (m, 2 H), 1.57 (s,
9 H), 1.50 (d, J = 10.2 Hz, 1 H), 1.45–1.20 (m, 20 H), 1.13 (d, J =
10.2 Hz, 1 H), 0.87 (t, J = 6.3 Hz, 3 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 161.8, 147.4, 146.9, 146.0, 145.3, 145.1, 144.1, 143.0,
142.7, 138.0, 136.8, 134.6, 128.6, 127.8, 126.5, 126.4, 125.7, 125.3,
122.9, 122.8, 121.1, 118.9, 116.8, 116.4, 108.6, 99.3, 83.3, 71.1, 50.1,
43.4, 40.8, 32.3, 31.9, 30.5, 29.8, 29.6, 29.5, 29.4, 29.3, 28.3, 28.0, 25.2,
14.1 ppm. FTIR (neat): ν = 2924, 2852, 1660, 1601, 1535, 1501, 1407,
˜
1372, 1258, 1228, 1124, 810, 692 cm–1. HRMS (ESI-TOF): calcd. for
C49H54NO2S3 784.3317 [M + H]+; found 784.3287.
General Procedure for the Knoevenagel Condensation Reaction
and the Subsequent Removal of the tBu Group for the Synthe-
sis of 2a–2c and 3a–3c: tert-Butyl cyanoacetate and piperidine
(20 μL) were added to a stirred solution of aldehyde 16–21 in the
given solvent at room temperature under Ar. After stirring at the
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22.6, 14.1 ppm. FTIR (neat): ν = 2924, 1711, 1581, 1484, 1408, 1370,
1.62–1.55 (m, 2 H), 1.57 (s, 9 H), 1.46 (d, J = 10.1 Hz, 1 H), 1.45–1.20
(m, 20 H), 1.13 (d, J = 10.1 Hz, 1 H), 0.87 (t, J = 6.3 Hz, 3 H) ppm.
13C NMR (100 MHz, CDCl3): δ = 161.9, 148.4, 147.1, 146.1, 145.8,
145.2, 143.6, 142.7, 141.4, 140.7, 140.7, 138.7, 136.7, 134.7, 130.8,
130.4, 130.4, 128.8, 128.7, 128.2, 127.6, 127.4, 127.2, 125.2, 124.5,
124.3, 122.4, 118.4, 116.5, 108.5, 99.1, 83.4, 71.1, 50.0, 43.5, 40.8,
32.3, 31.9, 30.5, 30.0, 29.9, 29.6, 29.5, 29.3, 28.4, 28.0, 25.2, 22.7,
˜
1328, 1255, 1153, 804, 749 cm–1. HRMS (ESI-TOF): calcd. for
C53H59N2O2S4 883.3459 [M + H]+; found 883.3477.
Removal of the tert-butyl group gave dye 2b, yield quant.; dark-red
solid, m.p. 153–155 °C. 1H NMR (400 MHz, [D6]DMSO): δ = 8.50 (s, 1
H), 8.22 (s, 1 H), 7.66 (s, 1 H), 7.56 (d, J = 8.2 Hz, 2 H), 7.40 (s, 1 H),
7.35 (dd, J = 5.3, 1.0 Hz, 1 H), 7.31–7.26 (m, 5 H), 7.04 (dd, J = 5.3,
3.9 Hz, 1 H), 6.96 (d, J = 8.7 Hz, 1 H), 4.33 (d, J = 8.2 Hz, 1 H), 3.28
(d, J = 8.2 Hz, 1 H), 2.73 (t, J = 6.3 Hz), 2.37 (s, 1 H), 2.34 (s, 1 H),
1.60 (m, 2 H), 1.55–1.45 (m, 2 H), 1.28 (d, J = 6.7 Hz, 1 H), 1.40–1.15
(m, 20 H), 1.04 (d, J = 6.7 Hz, 1 H), 0.79 (t, J = 6.3 Hz, 3 H) ppm. 13C
14.1 ppm. FTIR (neat): ν = 2925, 2853, 2215, 1712, 1581, 1511, 1481,
˜
1407, 1370, 1328, 1253, 1153, 1135, 806, 759, 700 cm–1. HRMS (ESI-
TOF): calcd. for C63H67N2O2S3 979.4365 [M + H]+; found 979.4370.
Removal of the tert-butyl group gave dye 3a, yield 85 %; dark-red
1
NMR (100 MHz, [D6]DMSO): δ = 163.5, 147.0, 146.7, 146.6, 144.1, solid, m.p. 150–155 °C H NMR (400 MHz, [D6]DMSO): δ = 8.51 (s, 1
143.0, 142.4, 142.2, 137.8, 136.8, 134.6, 131.6, 128.0, 127.6, 126.2, H), 8.24 (s, 1 H), 7.66 (s, 1 H), 7.48–7.38 (m, 4 H), 7.32 (d, J = 7.7 Hz,
125.8, 125.5, 125.0, 124.8, 123.3, 122.1, 121.3, 118.5, 116.4, 108.2, 2 H), 7.29–7.22 (m, 5 H), 7.18 (d, J = 7.7 Hz, 2 H), 7.07 (d, J = 8.2 Hz,
97.8, 69.9, 49.1, 42.9, 31.6, 31.1, 29.5, 28.9, 28.8, 28.6, 27.7, 24.5, 21.9,
2 H), 7.02 (s, 1 H), 6.96 (d, J = 8.2 Hz, 2 H), 6.88 (d, J = 8.2 Hz, 1 H),
4.33 (d, J = 8.2 Hz, 1 H), 3.25 (d, J = 8.2 Hz, 1 H), 2.74 (t, J = 6.7 Hz,
13.7 ppm. FTIR (neat): ν = 2924, 2853, 1569, 1483, 1403, 1375, 1258,
˜
808, 687 cm–1. HRMS (ESI-TOF): calcd. for C49H51N2O2S4 827.2833 [M 2 H), 2.34 (s, 1 H), 2.31 (s, 1 H), 1.70–1.58 (m, 2 H), 1.56–1.42 (m, 2
+ H]+; found 827.2811.
H), 1.45–1.20 (m, 21 H), 1.08 (d, J = 9.7 Hz, 1 H), 0.81 (t, J = 6.3 Hz,
3 H) ppm. 13C NMR (67.8 MHz, [D6]DMSO): δ = 163.6, 147.5, 147.1,
146.8, 144.2, 143.9, 142.6, 142.4, 140.8, 140.2, 139.4, 137.6, 136.7,
134.6, 131.9, 130.2, 129.8, 129.6, 129.0, 128.2, 127.5, 127.1, 126.7,
126.6, 124.9, 123.6, 122.0, 117.8, 116.5, 107.9, 97.6, 69.8, 48.9, 43.1,
31.7, 31.2, 29.5, 28.9, 28.8, 28.6, 27.7, 24.4, 22.0, 13.8 ppm. FTIR
Dye 2c: Knoevenagel condensation reaction of aldehyde 18
(24.0 mg, 0.0306 mmol), THF (2 mL), and tert-butyl cyanoacetate
(8.4 μL, 0.058 mmol). Column chromatography on silica gel, eluting
with chloroform, gave protected dye 24 (15.9 mg, 0.00175 mmol,
1
57 %) as a red solid, m.p. 93–96 °C. H NMR (400 MHz, CDCl3): δ =
(neat): ν = 3737, 3015, 2928, 2860, 2325, 2081, 1735, 1493, 1452,
˜
8.22 (s, 1 H), 7.89 (s, 1 H), 7.53 (d, J = 8.7 Hz, 2 H), 7.48 (d, J = 8.7 Hz,
2 H), 7.34–7.28 (m, 3 H), 7.26 (m, 1 H), 7.25 (s, 1 H), 7.10 (s, 1 H),
7.08 (d, J = 8.2 Hz, 1 H), 6.94 (d, J = 8.2 Hz, 2 H), 4.30 (d, J = 8.3 Hz,
1 H), 3.84 (s, 3 H), 3.35 (d, J = 8.2 Hz, 1 H), 2.81 (t, J = 6.7 Hz, 2 H),
1383, 1091, 1050, 875, 824, 635, 516 cm–1. HRMS (ESI-TOF): calcd.
for C59H59N2O2S3 923.3739 [M + H]+; found 923.3689.
Dye 3b: Knoevenagel condensation reaction of aldehyde 20
2.56 (s, 1 H), 2.41 (s, 1 H), 1.70 (m, 2 H), 1.64–1.55 (m, 2 H), 1.57 (s, (17.0 mg, 0.0224 mmol), THF (3 mL), and tert-butyl cyanoacetate
9 H), 1.53 (d, J = 9.2 Hz, 1 H), 1.45–1.20 (m, 20 H), 1.13 (d, J = 9.2 Hz, (8.4 μL, 0.058 mmol). Column chromatography on silica gel, eluting
1 H), 0.87 (t, J = 6.3 Hz, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ =
with chloroform, gave protected dye 26 (13.5 mg, 0.0153 mmol,
161.8, 158.4, 146.9, 146.8, 146.0, 145.4, 144.3, 143.3, 142.7, 138.8, 68 %) as a red amorphous solid: 1H NMR (400 MHz, CDCl3): δ = 8.22
136.8, 134.6, 133.9, 132.1, 128.6, 128.2, 127.3, 126.4, 126.0, 125.6, (s, 1 H), 7.88 (s, 1 H), 7.57 (d, J = 8.7 Hz, 2 H), 7.33 (s, 1 H), 7.30 (d,
125.2, 123.3, 118.5, 116.8, 116.4, 114.1, 108.8, 99.3, 83.3, 71.0, 55.3,
50.3, 43.4, 40.8, 32.3, 31.9, 30.5, 29.8, 29.6, 29.5, 29.4, 29.3, 28.4, 28.0,
J = 8.7 Hz, 2 H), 7.27 (s, 1 H), 7.27 (m, 1 H), 7.24 (s, 1 H), 7.23 (d, J =
5.3 Hz, 1 H), 7.06 (dd, J = 5.3, 3.9 Hz, 1 H), 7.04 (s, 1 H), 6.95 (d, J =
8.2 Hz, 1 H), 4.33 (d, J = 8.2 Hz, 1 H), 3.32 (d, J = 8.2 Hz, 1 H), 2.80
25.2, 22.6, 14.1 ppm. FTIR (neat): ν = 2924, 2853, 2214, 1710, 1602,
˜
1582, 1513, 1481, 1408, 1370, 1250, 1153, 802 cm–1. HRMS (ESI-TOF): (t, J = 6.7 Hz, 2 H), 2.52 (s, 1 H), 2.42 (s, 1 H), 1.74–1.67 (m, 2 H),
calcd. for C56H62N2O3S3 907.4001 [M + H]+; found 907.4000.
1.64–1.55 (m, 2 H), 1.57 (s, 9 H), 1.53 (d, J = 10.1 Hz, 1 H), 1.45–1.20
(m, 20 H), 1.13 (d, J = 10.1 Hz, 1 H), 0.87 (t, J = 6.3 Hz, 3 H) ppm.
13C NMR (100 MHz, CDCl3): δ = 161.8, 148.5, 147.0, 146.0, 145.7,
145.7, 145.1, 144.3, 142.7, 142.1, 138.7, 136.6, 134.6, 128.6, 128.0,
127.9, 127.3, 126.7, 125.3, 124.5, 124.3, 123.9, 122.4, 122.1, 119.6,
116.5, 108.1, 99.1, 83.3, 71.2, 50.0, 43.5, 40.8, 32.3, 31.9, 30.4, 30.3,
29.9, 29.6, 29.4, 29.3, 28.4, 28.0, 25.2, 22.6, 14.1 ppm. FTIR (neat):
Removal of the tert-butyl group gave dye 2c, yield quant.; dark-red
solid, m.p. 170–173 °C. 1H NMR (400 MHz, [D6]DMSO): δ = 8.51 (s, 1
H), 8.23 (s, 1 H), 7.67 (s, 1 H), 7.57 (d, J = 8.7 Hz, 2 H), 7.50 (d, J =
8.7 Hz, 2 H), 7.38 (s, 1 H), 7.32 (s, 1 H), 7.30 (d, J = 8.7 Hz, 2 H), 7.25
(dd, J = 8.3, 1.9 Hz, 1 H), 7.02 (d, J = 8.3 Hz, 1 H), 6.94 (d, J = 8.7 Hz,
2 H), 4.33 (d, J = 8.2 Hz, 1 H), 3.76 (s, 3 H), 3.30 (d, J = 8.2 Hz, 1 H),
2.75 (t, J = 7.2 Hz, 2 H), 2.40 (s, 1 H), 2.36 (s, 1 H), 1.61 (m, 2 H),
1.55–1.45 (m, 2 H), 1.39 (d, J = 8.6 Hz, 1 H), 1.40–1.10 (m, 20 H),
1.04 (d, J = 8.6 Hz, 1 H), 0.79 (t, J = 6.3 Hz, 3 H) ppm. 13C NMR
(67.8 MHz, [D6]DMSO): δ = 163.5, 158.0, 146.6, 146.0, 145.0, 143.8,
ν = 2924, 2853, 1713, 1580, 1503, 1480, 1406, 1369, 1328, 1253,
˜
1153, 810, 689 cm–1. HRMS (ESI-TOF): calcd. for C53H59N2O2S4
883.3459 [M + H]+; found 883.3435.
Removal of the tert-butyl group gave dye 3b, yield 58 %; dark-red
143.1, 142.6, 142.5, 137.8, 134.5, 132.7, 131.8, 131.0, 129.5, 127.5, solid, m.p. 145–149 °C. 1H NMR (400 MHz, [D6]DMSO): δ = 8.46 (s, 1
126.7, 126.2, 125.9, 125.1, 125.0, 122.8, 118.2, 116.6, 115.4, 114.1, H), 8.19 (s, 1 H), 7.61 (d, J = 8.7 Hz, 2 H), 7.45 (s, 1 H), 7.44 (s, 1 H),
108.5, 69.9, 55.0, 49.3, 42.9, 31.8, 31.2, 29.6, 28.9, 28.8, 28.6, 27.8,
7.40–7.36 (m, 1 H), 7.34–7.25 (m, 4 H), 7.09 (t, J = 3.9 Hz, 1 H), 6.92
27.1, 25.8, 24.6, 22.0, 13.8 ppm. FTIR (neat): ν = 2924, 2853, 1681, (d, J = 8.7 Hz, 1 H), 4.39 (d, J = 8.2 Hz, 1 H), 3.28 (d, J = 8.2 Hz, 1
˜
1567, 1480, 1401, 1256, 804 cm–1. HRMS (ESI-TOF): calcd. for
C52H55N2O3S3 851.3375 [M + H]+; found 851.3345.
H), 2.74 (t, J = 6.7 Hz, 2 H), 2.36 (s, 2 H), 1.70–1.58 (m, 2 H), 1.56–
1.42 (m, 2 H), 1.40–1.15 (m, 21 H), 1.07 (d, J = 9.7 Hz, 1 H), 0.80 (t,
J = 6.3 Hz, 3 H) ppm. 13C NMR (100 MHz, [D6]DMSO): δ = 163.3,
147.7, 146.4, 146.3, 143.7, 143.6, 143.3, 142.1, 141.4, 137.5, 136.8,
134.5, 131.1, 128.3, 127.7, 126.7, 126.3, 124.9, 124.4, 123.7, 122.4,
122.0, 119.3, 117.8, 107.7, 70.1, 61.9, 49.0, 43.0, 31.7, 31.1, 29.5, 28.9,
Dye 3a: Knoevenagel condensation reaction of aldehyde 19
(21.9 mg, 0.0256 mmol), THF (2 mL), and tert-butyl cyanoacetate
(7.3 μL, 0.051 mmol). Column chromatography on silica gel, eluting
with chloroform, gave protected dye 25 (24.2 mg, 0.0247 mmol,
28.8, 28.6, 27.7, 24.4, 21.9, 13.7 ppm. FTIR (neat): ν = 2924, 2853,
1
˜
96 %) as a red solid, m.p. 93–97 °C. H NMR (400 MHz, CDCl3): δ =
1682, 1570, 1464, 1402, 1372, 1256, 807, 500 cm–1. HRMS (ESI-TOF):
calcd. for C49H51N2O2S4 827.2833 [M + H]+; found 827.2820.
8.22 (s, 1 H), 7.88 (s, 1 H), 7.42–7.23 (m, 13 H), 7.06 (d, J = 8.7 Hz, 2
H), 7.02 (s, 1 H), 6.98 (d, J = 8.7 Hz, 1 H), 6.93 (s, 1 H), 6.90 (d, J =
4.8 Hz, 1 H), 4.23 (d, J = 8.2 Hz, 1 H), 3.28 (d, J = 8.2 Hz, 1 H), 2.79
(t, J = 6.7 Hz, 2 H), 2.46 (s, 1 H), 2.39 (s, 1 H), 1.74–1.67 (m, 2 H),
Dye 3c: Knoevenagel condensation reaction of aldehyde 21
(23.0 mg, 0.0306 mmol), THF (5 mL), and tert-butyl cyanoacetate
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(8.4 μL, 0.058 mmol). Column chromatography on silica gel, eluting
with chloroform, gave protected dye 27 (24.9 mg, 0.0274 mmol,
90 %) as a red solid, m.p. 95–100 °C. 1H NMR (400 MHz, CDCl3): δ =
8.23 (s, 1 H), 7.89 (s, 1 H), 7.53 (d, J = 8.7 Hz, 2 H), 7.52 (d, J = 8.7 Hz,
2 H), 7.34 (d, J = 8.7 Hz, 2 H), 7.33 (s, 1 H), 7.30 (m, 1 H), 7.28 (s, 1
H), 7.03 (s, 1 H), 6.96 (d, J = 8.7 Hz, 2 H), 6.94 (d, J = 5.3 Hz, 1 H),
4.35 (d, J = 7.8 Hz, 1 H), 3.85 (s, 3 H), 3.34 (d, J = 7.8 Hz, 1 H), 2.80
(t, J = 6.7 Hz, 2 H), 2.53 (s, 1 H), 2.43 (s, 1 H), 1.75–1.66 (m, 2 H),
1.61–1.55 (m, 2 H), 1.58 (s, 9 H), 1.54 (d, J = 10.1 Hz, 1 H), 1.45–1.20
(m, 20 H), 1.15 (d, J = 10.1 Hz, 1 H), 0.87 (t, J = 6.3 Hz, 3 H) ppm.
13C NMR (100 MHz, CDCl3): δ = 161.9, 158.8, 148.9, 147.1, 146.0,
145.8, 145.2, 142.7, 141.5, 138.6, 136.6, 134.4, 133.2, 128.6, 127.6,
127.3, 125.3, 124.4, 122.4, 120.0, 116.4, 114.2, 107.9, 99.0, 83.3, 71.3,
55.3, 50.0, 43.5, 40.8, 32.3, 31.9, 30.4, 29.9, 29.6, 29.4, 29.3, 28.4, 28.0,
25.2, 22.6, 14.1 ppm. FTIR (neat): ν = 2926, 2851, 2216, 1710, 1579,
˜
1499, 1479, 1405, 1369, 1327, 1249, 1153, 1136, 808 cm–1. HRMS
(ESI-TOF): calcd. for C56H63N2O3S3 907.4001 [M + H]+; found
907.3973.
Removal of the tert-butyl group gave dye 3c, yield 88 %; dark-red
solid, m.p. 156–159 °C. 1H NMR (400 MHz, [D6]DMSO): δ = 8.51 (s, 1
H), 8.22 (s, 1 H), 7.64 (s, 1 H), 7.56 (d, J = 8.7 Hz, 2 H), 7.55 (d, J =
8.7 Hz, 2 H), 7.42 (s, 1 H), 7.32 (d, J = 8.7 Hz, 2 H), 7.29–7.25 (m, 1
H), 7.24 (s, 1 H), 6.98 (d, J = 8.7 Hz, 2 H), 6.89 (d, J = 8.2 Hz, 2 H),
4.38 (d, J = 7.8 Hz, 1 H), 3.77 (s, 3 H), 3.26 (d, J = 7.8 Hz, 1 H), 2.73
(t, J = 7.2 Hz, 2 H), 2.35 (s, 2 H), 1.65–1.58 (m, 2 H), 1.53–1.48 (m, 2
H), 1.33 (d, J = 9.2 Hz, 1 H), 1.30–1.10 (m, 20 H), 1.06 (d, J = 9.2 Hz,
1 H), 0.80 (t, J = 6.8 Hz, 3 H) ppm. 13C NMR (100 MHz, [D6]DMSO):
δ = 163.5, 158.4, 148.1, 147.0, 146.8, 144.1, 142.4, 140.7, 137.6, 136.6,
134.4, 133.2, 132.1, 127.0, 126.8, 126.4, 125.0, 123.3, 122.0, 117.6,
116.4, 114.2, 107.3, 70.2, 55.0, 49.0, 43.0, 31.7, 31.2, 29.5, 29.0, 28.9,
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Pechy, M. Gratzel, Chem. Commun. 2008, 5194.
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28.8, 28.6, 27.7, 24.4, 21.9, 13.7 ppm. FTIR (neat): ν = 2924, 2853,
˜
1679, 1571, 1499, 1464, 1403, 1256, 1176, 807 cm–1. HRMS (ESI-TOF):
calcd. for C52H54N2O3S3 851.3375 [M + H]+; found 851.3329.
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Acknowledgments
The authors thank Mr. Kohei Kashibuchi and Mr. Keitaro Hashi-
moto, Tokyo Institute of Technology, for measuring the photo-
physical and electrochemical properties of the dyes.
Keywords: Dyes/Pigments · Sensitizers · Solar cells · Sulfur
heterocycles · Fused-ring systems · Cross-coupling · Palladium
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Received: September 12, 2015
Published Online: December 9, 2015
Eur. J. Org. Chem. 2016, 508–517
www.eurjoc.org
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© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim