Pd-catalyzed direct C-H arylation of thieno[3,4-c]pyrrole-4,6-dione (TPD): A step-economical synthetic alternative to access TPD-centred symmetrical small molecules

Article abstract of DOI:10.1039/c4ra05380j

We demonstrate a step-economical and viable synthetic alternative to access a series of thieno[3,4-c]pyrrole-4,6-dione (TPD)-based π-conjugated molecules through Pd-catalyzed direct C-H arylations. A comprehensive synthetic study including the screening of various kinds of palladium catalysts, ligands, and bases is reported. Under the optimum reaction conditions, TPD and its common derivatives underwent efficient and mild direct C-H arylations with a variety of functionalized bromoarenes. Functional groups such as ester, nitrile, ketone, aldehyde, and halide were well-tolerated, which substantially extended the reaction scope. We hope the reported method will provide materials scientists a relatively greener synthetic route to efficiently prepare TPD-containing π-functional materials. This journal is the Partner Organisations 2014.

Full text of DOI:10.1039/c4ra05380j

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PAPER
Pd-catalyzed direct C–H arylation of thieno[3,4-c]
pyrrole-4,6-dione (TPD): a step-economical
synthetic alternative to access TPD-centred
symmetrical small molecules†
Cite this: RSC Adv., 2014, 4, 35868
*
Shan-Yun Chang, Po-Han Lin and Ching-Yuan Liu
We demonstrate a step-economical and viable synthetic alternative to access a series of thieno[3,4-c]
pyrrole-4,6-dione (TPD)-based p-conjugated molecules through Pd-catalyzed direct C–H arylations. A
comprehensive synthetic study including the screening of various kinds of palladium catalysts, ligands,
and bases is reported. Under the optimum reaction conditions, TPD and its common derivatives
underwent efficient and mild direct C–H arylations with a variety of functionalized bromoarenes.
Functional groups such as ester, nitrile, ketone, aldehyde, and halide were well-tolerated, which
substantially extended the reaction scope. We hope the reported method will provide materials scientists
a relatively greener synthetic route to efficiently prepare TPD-containing p-functional materials.
Received 6th June 2014
Accepted 5th August 2014
DOI: 10.1039/c4ra05380j
www.rsc.org/advances
bidirectional facile conjugation extension from the electron-
decient TPD core-structure still remains, to the best of our
Introduction
knowledge, unexplored. Therefore, we report herein the Pd-
catalyzed direct C–H arylation of TPD or its derivatives with a
variety of functionalized bromoarenes can be achieved under
pre-optimized reaction conditions. We anticipated that by
examining carefully the reaction parameters and substrate
scope would allow us to nd an effective and broadly applicable
catalytic system for the efficient synthesis TPD-centred D–A–D3b
or A0–A–A09a,c,i type (D: donor; A: acceptor) p-functional mole-
cules (Scheme 1).
In recent years, the transition-metal-catalyzed direct C–H
(hetero)arylation is emerging as a viable and key synthetic
alternative to traditional C(sp2)–C(sp2) forming reactions
because it avoids the use of air-sensitive or toxic organometallic
compounds such as Grignard reagents or organotin species.1
More recently, further application of the direct C–H (hetero)
arylations in the efficient synthesis of various functional p-
conjugated oligomers and polymers has attracted particular
research attention and numerous remarkable results have been
disclosed by some research groups.1c,2 In order to extend the
substrate scope of the existing C–H arylation technology and,
simultaneously, to bridge the research area of synthetic meth-
odology with organic electronics, our attention has been drawn
to the preparation of thieno[3,4-c]pyrrole-4,6-dione (TPD)-based
functional small molecules3 or polymers4 and their potential
applications as organic eld-effect transistors (OFET)5 and
organic photovoltaic cells (OPVC).6 TPD is an electron-decient
unit exhibiting superior planarity and solubility, which is
benecial to the charge transfer and device fabrication while
incorporated into various conjugated systems.7 Despite the
employment of TPD as key conjugated backbone for optoelec-
tronic applications has been widely investigated,3–7 a step-
economical and comprehensive synthetic study involving the
screening of all required reaction parameters for the
Results and discussion
In order to obtain the optimum reaction conditions, the direct
C–H arylation was rst examined with 5-hexyl-4H-thieno[3,4-c]
Department of Chemical and Materials Engineering, National Central University,
Jhongli City, Taiwan 320, R.O.C. E-mail: cyliu0312@ncu.edu.tw; Tel:
+886-3-422-7151
† Electronic supplementary information (ESI) available: NMR spectra (1H and 13C)
Scheme 1 Traditional and step-economical synthetic routes to access
thieno[3,4-c]pyrrole-4,6-dione (TPD)-based p-functional molecules.
for compounds 1, 3, 4, 5 and 6. See DOI: 10.1039/c4ra05380j
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pyrrole-4,6-dione 1a and bromobenzene 2a. Initially, as tetrabutylammonium bromide in DMF, 100 ꢀC, 12 h). However,
shown in Table 1, we followed a general procedure oen the desired product 3a was isolated in only 13% yield (entry 1,
used in Pd-catalyzed C–H arylation of heteroarenes,8 in Table 1). In entry 2, an improved yield (40%) was obtained while
which the two-fold phenylation of 1a was conducted under a KOAc was replaced with Cs2CO3 and a phosphine ligand (PPh3)
simple and phosphine-free reaction condition in polar was added. Prolonging the reaction time to 24 h under identical
aprotic solvent (palladium(II) acetate, potassium acetate, and reaction conditions described in entry 2 did not give a notable
enhancement of yield (43%, entry 3). With these preliminary
results in hand, we reasoned that switching the nature of
solvent from polar to less polar might be crucial to the direct
C–H arylation of TPD. Indeed, as the reaction was performed in
nonpolar solvent (toluene), a considerably improved yield was
observed (70%, entry 4). Therefore, we turned to use toluene as
the primary solvent for the subsequent screening of other
reaction parameters. Firstly, we endeavored to examine the
direct C–H arylation using various kinds of palladium catalysts
(entries 5–10). Both cis-PdCl2(PPh3)2 and its trans-form were
found to be much less effective and gave poor yields (trace to
10%, entries 5–6). Likewise, PdCl2(dppf) was tested to afford the
product in only 5% yield (entry 7). From entry 8 through 10,
three kinds of commonly used Pd(0)-catalysts were also inves-
tigated under identical reaction conditions. However, none of
them gave satisfactory results (0–20%). Accordingly, palladiu-
m(II) acetate was used as the optimum catalyst for subsequent
optimization since it exhibits the highest activity.
Table 1 Optimization of the Pd-catalyzed direct C–H arylation of
hexyl-TPD with bromobenzenea
Entry [Pd]
Ligand
Base
Solvent Yieldg (%)
1b,c
2c
3
Pd(OAc)2
—
KOAc
Cs2CO3 DMF
Cs2CO3 DMF
Cs2CO3 Toluene 70
Cs2CO3 Toluene 10
Cs2CO3 Toluene Trace
Cs2CO3 Toluene
Cs2CO3 Toluene 20
Cs2CO3 Toluene
DMF
13
40
43
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
PdCl2(PPh3)2 PPh3
PdCl2(PPh3)2 PPh3
PdCl2(dppf) PPh3
PPh3
PPh3
PPh3
4
5
6d
7
5
8
9
Pd2(dba)3
Pd/C
PPh3
PPh3
The direct C–H arylation of TPD was then examined with a
variety of ligands (20 mol%) in the presence of Pd(OAc)2 (10
mol%) and Cs2CO3 (2.4 equiv.) in toluene at 110 ꢀC for 24 h
(entries 11–22). Firstly, two monodentate trialkylphosphine
ligands were successively employed to furnish the desired
product in good yields (77–86%, entries 11–12). From entry 13
through 15, the arylation was performed, respectively, with
three different kinds of constitutional isomers of tritolylphos-
phine, resulting in the formation of 3a in moderate to excellent
yields (71–96%). Further, the more electron-rich ligand (L2),
however, did not provide a better yield (75%, entry 16),
presumably due to the increased steric hindrance. The dia-
lkylarylphosphine ligands, such as Johnphos and Xphos, were
also tested to give the product in relatively poor to moderate
yields (39 and 63%, entries 17, 18, respectively). In addition, we
have carried out the C–H arylation using a number of bidentate
ligands. In entries 19 and 20, the reaction underwent with dppb
and dppf to afford 3a in 85% and 34% yield, respectively,
whereas the N,N-ligands such as bipyridyl and phenanthroline
were shown to be ineffective in the direct arylations of TPD (0%,
starting materials recovered, entries 21–22). Finally, under a
phosphine-ligand-free condition, the C–H arylation hardly
occurred and only trace amount of the desired product was
isolated (entry 23). Subsequent screenings of base and solvent
effects were carried out using the combination of Pd(OAc)2 and
P(m-tolyl)3 since entry 14 had shown the optimum result. As
expected, K2CO3 provided a comparable yield (90%, entry 24).
Importantly, another inorganic base, tripotassium phosphate
(K3PO4), which has excellent solubility in nonpolar solvent also
afforded the product with a good yield (88%, entry 25), whereas
the less basic Na2CO3 gave a diminished yield (31%, entry 26).
In the absence of base, 3a was formed in trace amount (entry
27). Therefore, we selected Cs2CO3 for the nal solvent
0
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29e
30
31
32f
Pd(PPh3)4
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
—
PCy3
L1
P(p-tolyl)3
P(m-tolyl)3
P(o-tolyl)3
L2
JohnPhos
XPhos
Dppb
Cs2CO3 Toluene 15
Cs2CO3 Toluene 81
Cs2CO3 Toluene 86
Cs2CO3 Toluene 90
Cs2CO3 Toluene 96
Cs2CO3 Toluene 71
Cs2CO3 Toluene 75
Cs2CO3 Toluene 39
Cs2CO3 Toluene 63
Cs2CO3 Toluene 85
Cs2CO3 Toluene 34
Dppf
Bipyridyl
Cs2CO3 Toluene
0
0
Phenanthroline Cs2CO3 Toluene
—
Cs2CO3 Toluene Trace
P(m-tolyl)3
P(m-tolyl)3
P(m-tolyl)3
P(m-tolyl)3
P(m-tolyl)3
P(m-tolyl)3
P(m-tolyl)3
P(m-tolyl)3
P(m-tolyl)3
K2CO3
K3PO4
Toluene 90
Toluene 88
Na2CO3 Toluene 31
Toluene Trace
—
Cs2CO3 o-Xylene 93
Cs2CO3 Dioxane 91
Cs2CO3 NMP
Cs2CO3 DMSO
17
12
Cs2CO3 CH3CN 29
a
Unless specied, the C–H arylation was conducted with TPD 1a (1
equiv.) and bromobenzene 2a (2.5 equiv.) in the presence of [Pd]-
catalyst (10 mol%), ligand (20 mol%), base (2.4 equiv.) in 3 mL
b
solvent at 110 ꢀC for 24 h.
In addition to KOAc,
c
tetrabutylammonium bromide (TBAB, 1.0 equiv.) was added. The
d
e
reaction time was 12 h. trans-PdCl2(PPh3)2 was used. The reaction
f
temperature was 100 ꢀC. The reaction temperature was 80 ꢀC.
g
Isolated yields.
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optimization. Firstly, another frequently used nonpolar solvent of TPD (91%, entry 29). On the contrary, the reaction was also
(o-xylene) was tested and we were pleased to nd that the performed with a series of polar aprotic solvents, respectively. It
product was isolated in excellent yield (93%, entry 28). Besides, appears, however, that the direct arylation of TPD was impeded
it is worth noting that, 1,4-dioxane, a low-polarity ethereal in polar solvents, and 3a was then obtained all in poor yields
solvent, was demonstrated to promote the direct C–H arylation (12–29%, entries 30–32). Thus, we concluded that the polarity of
Table 2 Substrate scope: Pd-catalysed direct C–H arylation of hexyl-substituted TPD 1a with various aryl bromides 2b–ua
a
Unless specied, the C–H arylation was conducted with TPD 1a (1 mmol) and the corresponding aryl bromides 2b–u (2.5 mmol) in the presence of
b
Pd(OAc)2 (10 mol%), P(m-tolyl)3 (20 mol%), and Cs2CO3 (2.4 mmol) in toluene (3 mL) at 110 ꢀC for 24 h. Isolated yield.
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Table 3 Substrate scope: Pd-catalysed direct C–H arylation using
TPD's derivative (1b) and its furan congener (1c)a
solvent would have a signicant inuence on the reaction
conversion while utilizing TPD as the C–H activation substrate.
Accordingly, the nonpolar toluene or o-xylene would be selected
as the best solvent for the subsequent investigation of substrate
scope.
The optimum reaction condition acquired in entry 14 was
used to further explore the substrate scope of this methodology
by treating hexyl-substituted TPD 1a with various functionalized
aryl bromides 2b–u (Table 2). Firstly, reaction of 1a with ethyl 4-
bromobenzoate 2b under [Pd(OAc)2, P(m-tolyl)3, and Cs2CO3 in
ꢀ
toluene at 110 C for 24 h] led to the formation of para-diester
3b in 66% yield. Interestingly, when 2-bromobenzoate 2c was
used, ortho-diester 3c was obtained in excellent yield (94%),
presumably owing to the formation of coordinatively stabilized
oxidative-addition intermediate [Ar–Pd(II)–Br] resulting from
the chelation of ortho-ester group to Pd(II). Subsequently, we
found that the sensitive but synthetically useful functionalities
such as nitrile, ketone, and aldehyde were well tolerated under
present reaction conditions, which step-economically elongated
the conjugation length of TPD and simultaneously installed
these readily transformable functional groups at both ends,
affording desired 3d–3f in good to excellent yields (70–93%). A
chemoselective direct C–H arylation was achieved by the reac-
tion of TPD with 1-bromo-4-chlorobenzene 2g, giving the
dichloro species 3g in 85% yield. Next on, we examined a series
of uorine-containing coupling partners 2h–2m. The resulting
TPD-based (poly)uorinated oligomers 3h–3m were readily
isolated in 55–95% yields. Because of the alkyl chain of TPD,
these compounds generally exhibit good solubility in acetone,
chloroform, and THF, which is important for further device
fabrications. These uorine-containing or -terminated products
3h–3m could be important for the application of organic eld-
effect transistors.9
a
Reaction conditions: 1b–c (1 mmol), aryl bromides (2.5 mmol),
Pd(OAc)2 (10 mol%), P(m-tolyl)3 (20 mol%), and Cs2CO3 (2.4 mmol),
b
toluene (3 mL), 110 ꢀC, 24 h. Isolated yield.
TPD, furo[3,4-c]pyrrole-4,6-dione (FPD) (1c) was found to
In addition to the electron-withdrawing bromoarenes, we've successfully undergo the C–H arylation under our optimized
also tested a number of electron-donating/-rich ones 2n–u. We conditions and offered a good yield (5a) in the reaction with
found that the isolated yields obtained by treating TPD with the bromobenzene. The other example using FPD demonstrated
corresponding 2- or 4-bromotoluene did not differ greatly (82% that the versatile cyano group was also tolerated and the
for 3n; 87% for 3o). Other alkylated products 3p and 3q exhib- resulting di-nitrile product (5b) was isolated in 62% yield.
iting superior solubility in most organic solvents were synthe-
In order to shed light on the importance of high functional-
sized in moderate yields (86% and 72%). Similar to the ester group compatibility of our method and demonstrate this
group, the stabilization effect was observed again while the strategy could become a step-economical and viable synthetic
ortho-methoxy group was involved, furnishing 3s in 80% yield alternative for the preparation of TPD-incorporated functional
(64%for the para-isomer 3r). Of particular importance, triphe- small molecules, we describe a two-step facile synthesis, in
nyamine (TPA), a good hole-transporting moiety,10 could be which the readily available di-aldehyde species (3f) of Table 2
step-economically installed at both ends of TPD, thus leading to was further end-capped with the strongly electron-withdrawing
the formation of a donor–acceptor–donor (D–A–D) type mole- dicyanovinyl groups by an operationally simple and solvent-free
cule 3t in 66% yield. In addition, the pyrene-capped TPD 3u was mixing procedure under air,11 which resulted in the formation
also efficiently prepared through present methodology (71%).
The scope of the direct C–H arylation with respect to TPD's quantitative yield (Scheme 2).
of the A0-p–A–p-A012 (A or A0: acceptors) type oligomer (6) in
derivatives was then investigated in Table 3. Reaction of
A plausible reaction mechanism was proposed in Scheme 3.
ethylhexyl-substituted TPD (1b) with bromoarenes carrying Aer the oxidative addition, coordination of the bicarbonate ion
electron-withdrawing groups such as ester or triuoromethyl to palladium center generated the intermediate A. Subse-
group gave moderate to good yields (4a, 4b). However, while the quently, the proton abstraction of TPD would take place
electron-donating methyl or triphenyamino group, relatively possibly via a concerted metalation-deprotonation (CMD)
lower isolated yields were obtained (4c and 4d) because in both mechanism to afford intermediate B, which would then
cases the separation of desired 4c or 4d from the mono-arylated undergo the reductive elimination to give the desired arylated
byproduct was difficult. On the other hand, the congener of product C and regenerate Pd(0) species.
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Experimental
General information
Unless otherwise indicated, all reactions were carried out with
magnetic stirring and, if air or moisture sensitive, in ame-
dried glassware under nitrogen. 5-(Alkyl)-4H-thieno[3,4-c]
pyrrole-4,6(5H)-dione (TPD) (1a–b) and its congener (FPD) (1c)
were synthesized according to the literatures.13,14 Reagents
including various bromoarenes (2a–u), palladium catalysts,
ligands, and additives (bases) are commercially available.
Anhydrous solvents such as N,N-dimethylformamide (DMF),
toluene, o-xylene, dioxane, N-methyl-2-pyrrolidone (NMP),
dimethyl sulfoxide (DMSO) and acetonitrile were purchased
from Sigma-Aldrich and used directly without further purica-
tions. Syringes used to transfer reagents and solvents were
purged with nitrogen prior to use. Reactions were monitored by
thin layer chromatography (TLC, aluminum plates coated with
silica gel, Merck 60, F-254). The spots were visualized by UV
light. Flash column chromatography was performed using silica
gel 60 (spherical, 63–210 mm) from Merck. The diameters of the
columns and the amount of silica gel loaded were calculated
according to the recommendation of W. C. Still.15 Melting
points were measured on a Fargo MP-2D apparatus. NMR
spectra were recorded on a Bruker Magnet System 300 MHz/54
mm instrument. Chemical shis were given relative to CDCl3
(7.26 ppm for 1H NMR, 77.0 ppm for 13C NMR), DMSO-d6 (2.50
ppm for 1H NMR, 39.4 ppm for 13C NMR), CD2Cl2 (5.32 ppm for
1H NMR, 54.0 ppm for 13C NMR). For the characterization of the
observed signal multiplicities, the following abbreviations were
applied: s (singlet), d (doublet), dd (double doublet), dt (double
triplet), t (triplet), td (triple doublet), q (quartet), quint (quintet),
m (multiplet), as well as br (broad). Mass spectra were recorded
on a JEOL JMS-700 for electron impact ionization (EI) and high
resolution mass spectra (HRMS) on a JEOL JMS-700 spectrom-
eters. Fast atom bombardment (FAB) samples were recorded in
a 3-nitrobenzyl alcohol matrix.
Scheme 2 A two-step facile synthesis of the dicyano-terminated A0-
p–A–p-A0 type oligomer.
Scheme 3 Plausible reaction mechanism.
Conclusions
In summary, we have demonstrated a step-economical synthetic
strategy through direct C–H arylations for the facile preparation
General procedure for the synthesis of TPD (1a–b)
Synthesis of 1H,3H-thieno[3,4-c]furan-1,3-dione. In a 500 mL
double-necked round-bottom ask equipped with a reux
condenser, 3,4-thiophenedicarboxylic acid (1.0 equiv.) was dis-
solved in acetic anhydride and the solution was stirred at 140 ꢀC
for overnight. The reaction mixture was then cooled to room
temperature and the solvent was removed under reduced
pressure to yield a dark brown solid, and the crude product was
used directly for the next step without further purication.
Synthesis of 5-(alkyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione.
The crude product obtained from the previous step was dis-
solved in toluene and the corresponding amine (1.5 equiv.) was
then added to the stirring solution. The reaction mixture was
heated at reux (ꢁ140 ꢀC) for 24 h before it was cooled to room
temperature. The solvent was evaporated under reduced pres-
sure. The resulting solid was dissolved in thionyl chloride. The
mixture was then heated at reux for 3 hours before it was
cooled to room temperature. The solvent was distilled off under
of
a variety of thieno[3,4-c]pyrrole-4,6-dione (TPD)-based
symmetrical oligoarenes. A broad range of important func-
tional groups such as ester, nitrile, ketone, aldehyde, and halide
are compatible with the optimum reaction conditions, in which
a comprehensive screening of all required reaction parameters
was carried out. Interestingly, it was found that the direct C–H
arylation of TPD would be best performed in nonpolar solvents
such as toluene, xylene, or dioxane. In addition, the direct C–H
arylation also proceeded smoothly with TPD's derivative and its
furan congener (FPD), which further extended the reaction
scope. Therefore, we wish present synthetic approach would
become a more efficient and viable synthetic alternative to
traditional cross-couplings, thereby providing
a relatively
greener route to access TPD-containing p-functional small
molecules. Further application in organic electronics of the
obtained products is currently underway in our laboratory.
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ambient pressure by simple distillation. Purication by ash (dichloromethane–hexane
¼
2 : 1) yielded the desired
chromatography gave the desired products 1a–b.
product 1c.
5-Hexyl-4H-furo[3,4-c]pyrrole-4,6(5H)-dione (1c). The title
5-Hexyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione.13 (1a) The title
compound was prepared from 3,4-thiophenedicarboxylic acid compound was prepared from dimethyl-3,4-furandicarboxylate
(5.40 g, 31.4 mmol), acetic anhydride (60 mL), 1-hexylamine (2.75 g, 14.9 mmol), ethanol (90 mL), KOH (3.35 g, 59.6
(4.80 g, 47.2 mmol), toluene (100 mL), and thionyl chloride (200 mmol), oxalyl chloride (32.5 mL), 1-hexylamine (1.35 g, 13.3
mL) according to the general procedure for the synthesis of TPD mmol), and DMAP (470 mg, 3.85 mmol) according to the
and yielding aer column chromatography (ethyl acetate– general procedure for the synthesis of FPD and yielding aer
hexane ¼ 1 : 9) the pure product 1a (5.90 g, 79%). A pale orange column chromatography (dichloromethane–hexane ¼ 2 : 1) the
solid; m.p.: 120.3–122.3 ꢀC. 1H NMR (CDCl3, 300 MHz, ppm): d pure product 1c (1.19 g, 36%). A white solid; m.p.: 116.2–116.6
7.79 (s, 2H), 3.59 (t, J ¼ 6.00 Hz, 2H), 1.55–1.68 (m, 2H), 1.22– ꢀC. 1H NMR (CDCl3, 300 MHz, ppm): d 7.74 (s, 2H), 3.57 (t, J ¼
1.37 (m, 6H), 0.86 (t, J ¼ 6.00, 3H); 13C NMR (CDCl3, 75 MHz, 7.5 Hz, 2H), 1.54–1.67 (m, 2H), 1.21–1.35 (m, 6H), 0.86 (t, J ¼ 7.1,
ppm): d 162.6, 136.6, 125.4, 38.4, 31.3, 28.4, 26.5, 22.5, 14.0.
5-(2-Ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione.13
3H); 13C NMR (CDCl3, 75 MHz, ppm): d 161.6, 138.5, 122.4, 38.5,
(1b) 31.2, 28.2, 26.4, 22.4, 13.9; MS (EI, 70 ev): 221 (M+, 6%), 150
The title compound was prepared from 3,4-thio- (82%), 123 (93%), 66 (100%); HRMS (EI): calcd for C12H15NO3:
phenedicarboxylic acid (5.40 g, 31.4 mmol), acetic anhydride (60 221.1052%, found: 221.1054%.
mL), 2-ethylhexylamine (6.10 g, 47.2 mmol), toluene (100 mL),
and thionyl chloride (200 mL) according to the general proce-
dure for the synthesis of TPD and yielding aer column chro-
matography (ethyl acetate–hexane ¼ 1 : 9) the pure product 1b
General procedure for Table 1
To a solution of Pd(OAc)2 (10 mol%), P(m-tolyl)3 (20 mol%), and
Cs2CO3 (2.40 mmol) in toluene (3 mL) in a ame-dried Schlenk
tube (20 mL) were added TPD (1.00 mmol) and the corre-
sponding bromobenzene (2.50 mmol) under N2. The reaction
mixture was then heated at 110 ꢀC under N2 for 24 h. Aer the
reaction mixture had cooled to room temperature, water
(10 mL) was added. The mixture was extracted with ethyl acetate
(2 ꢂ 30 mL), and the combined organic layers were washed with
brine (50 mL), dried (Na2SO4) and concentrated in vacuo. Puri-
cation by ash chromatography (ethyl acetate–hexane) yielded
the desired products 3a.
1
ꢀ
(6.20 g, 75%). A pale brown solid; m.p.: 72.4–74.0 C. H NMR
(CDCl3, 300 MHz, ppm): d 7.80 (s, 2H), 3.51 (d, J ¼ 7.3 Hz, 2H),
1.72–1.87 (m, 1H), 1.19–1.40 (m, 8H), 0.83–0.93 (m, 6H); 13C
NMR (CDCl3, 75 MHz, ppm): d 162.9, 136.6, 125.4, 42.3, 38.1,
30.4, 28.4, 23.8, 23.0, 14.0, 10.4.
General procedure for the synthesis of FPD14 (1c)
Synthesis of furan-3,4-dicarboxylic acid. Dimethyl-3,4-
furandicarboxylate (2.75 g, 14.9 mmol) and ethanol (88 mL)
were placed in a round-bottomed ask mounted over a
magnetic stirrer and maintained at 50–60 ꢀC. Subsequently,
KOH (3.35 g, 59.6 mmol) was added and the reaction mixture
was stirred for 2 h before it was quenched by water. The
unreacted dimethyl-3,4-furandicarboxylate was removed by
ether extraction and the desired carboxylic acid was obtained by
the following method: the aqueous phase was acidied (pH ¼ 2)
with 6 N HCl and then extracted with ether. The combined ether
extracts were dried with Na2SO4 and concentrated in vacuo. The
pure product was obtained aer drying under vacuum (1.82 g,
86%).
Representative example of Table 1
5-Hexyl-1,3-diphenyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (3a).
The title compound was prepared from 1a (237 mg, 1.00 mmol)
and bromobenzene (2a) (393 mg, 2.50 mmol) according to the
general procedure for Table 1 and yielding aer column chro-
matography (ethyl acetate–hexane ¼ 3 : 97) the pure product 3a
(374 mg, 96%). A white solid; m.p.: 97.9–98.2 ꢀC. 1H NMR
(CDCl3, 300 MHz, ppm): d 8.13 (dd, J ¼ 7.8, 1.5 Hz, 4H), 7.35–7.55
(m, 6H), 3.67 (t, J ¼ 7.5 Hz, 2H), 1.60–1.75 (m, 2H), 1.21–1.43 (m,
6H), 0.88 (t, J ¼ 6.82 Hz, 3H); 13C NMR (CDCl3, 75 MHz, ppm): d
163.0, 145.0, 130.5, 130.4, 130.1, 128.9, 128.1, 38.6, 31.4, 28.4,
26.6, 22.5, 14.0; MS (FAB): 390 ([M + 1]+, 100%), 318 (46%), 228
(51%); HRMS (FAB): calcd for C24H23NO2S: 389.1449%, found:
389.1453%.
Synthesis of furan-3,4-dicarbonyl dichloride. Oxalyl chloride
(32.5 mL) was added slowly to the furan-3,4-dicarboxylic acid
(2.00 g, 12.8 mmol). The mixture was then heated at reux for 2
h before it was cooled to room temperature. The volatiles were
General procedure for Table 2
removed under reduced pressure, and the obtained crude To a solution of Pd(OAc)2 (10 mol%), P(m-tolyl)3 (20 mol%), and
product was used directly in the next step without further Cs2CO3 (2.40 mmol) in toluene (3 mL) in a ame-dried Schlenk
purication.
tube (20 mL) were added TPD 1a (1.00 mmol) and the corre-
Synthesis of 5-hexyl-4H-furo[3,4-c]pyrrole-4,6(5H)-dione. A sponding aryl bromides (2.50 mmol) under N2. The reaction
mixture of 1-hexylamine (1.35 g, 13.3 mmol), furan-3,4- mixture was then heated at 110 ꢀC under N2 for 24 h. Aer the
dicarbonyl dichloride (2.00 g, 12.8 mmol) and DMAP (470 mg, reaction mixture had cooled to room temperature, water (10
3.85 mmol) was heated at 140 ꢀC for 2 h before the mixture was mL) was added. The mixture was extracted with ethyl acetate (2
cooled to room temperature. The mixture was extracted with ꢂ 30 mL), and the combined organic layers were washed with
ethyl acetate (2 ꢂ 30 mL), and the combined organic layers were brine (50 mL), dried (Na2SO4) and concentrated in vacuo. Puri-
washed with sodium carbonate (100 mL), dried (Na2SO4) and cation by ash chromatography (ethyl acetate–hexane) yielded
concentrated in vacuo. Purication by column chromatography the desired products 3b–u.
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Diethyl 4,40-(5-hexyl-4,6-dioxo-5,6-dihydro-4H-thieno[3,4-c]-
4,40-(5-Hexyl-4,6-dioxo-5,6-dihydro-4H-thieno[3,4-c]pyrrole-
pyrrole-1,3-diyl)dibenzoate (3b). The title compound was 1,3-diyl)dibenzaldehyde (3f). The title compound was prepared
prepared from 1a (237 mg, 1.00 mmol) and ethyl 4-bromo- from 1a (237 mg, 1.00 mmol) and 4-bromobenzaldehyde (2f)
benzoate (2b) (573 mg, 2.50 mmol) according to the general (463 mg, 2.50 mmol) according to the general procedure for
procedure for Table 2 and yielding aer column chromatog- Table 2 and yielding aer column chromatography (ethyl
raphy (ethyl acetate–hexane ¼ 10 : 90) the pure product 3b (352 acetate–hexane ¼ 20 : 80) the pure product 3f (312 mg, 70%). A
1
1
ꢀ
mg, 66%). A yellow solid; m.p.: 167.9–168.4 ꢀC. H NMR (CDCl3, yellow solid; m.p.: 163.6–164.4 C. H NMR (CDCl3, 300 MHz,
300 MHz, ppm): d 8.20 (d, J ¼ 8.6 Hz, 4H), 8.12 (d, J ¼ 8.6 Hz, ppm): d 10.03 (s, 2H), 8.29 (d, J ¼ 7.9 Hz, 4H), 7.95 (d, J ¼ 7.9 Hz,
4H), 4.40 (q, J ¼ 7.1 Hz, 4H), 3.67 (t, J ¼ 7.3 Hz, 2H), 1.59–1.75 4H), 3.66 (t, J ¼ 6.9 Hz, 2H), 1.57–1.81 (m, 2H), 1.18–1.49
(m, 2H), 1.24–1.47 (m, 12H), 0.88 (t, J ¼ 6.7 Hz, 3H); 13C NMR (m, 6H), 0.87 (s, 3H); 13C NMR (CDCl3, 75 MHz, ppm): d 191.1,
(CDCl3, 75 MHz, ppm): d 165.4, 162.1, 143.5, 133.8, 131.7, 131.3, 162.4, 143.8, 137.0, 135.5, 132.6, 130.2, 128.6, 38.9, 31.4, 28.4,
129.8, 127.6, 61.1, 38.6, 31.2, 28.2, 26.5, 22.4, 14.1, 13.9; MS 26.6, 22.5, 14.0; MS (EI, 70 ev): 445 (M+, 60%), 374 (46%), 149
(FAB): 534 ([M + 1]+, 46%), 488 (31%), 141 (55%), 106 (64%), 51 (50%), 71 (42%), 58 (100%); HRMS (EI): calcd for C26H23NO4S:
(100%); HRMS (FAB): calcd for C30H31NO6S: 533.1872%, found: 445.1348%, found: 445.1340%.
533.1876%.
1,3-Bis(4-chlorophenyl)-5-hexyl-4H-thieno[3,4-c]pyrrole-
Diethyl 2,20-(5-hexyl-4,6-dioxo-5,6-dihydro-4H-thieno[3,4-c]- 4,6(5H)-dione (3g). The title compound was prepared from 1a
pyrrole-1,3-diyl)dibenzoate (3c). The title compound was (237 mg, 1.00 mmol) and 1-bromo-4-chlorobenzene (2g) (479
prepared from 1a (237 mg, 1.00 mmol) and ethyl 2-bromo- mg, 2.50 mmol) according to the general procedure for Table 2
benzoate (2c) (573 mg, 2.50 mmol) according to the general and yielding aer column chromatography (ethyl acetate–
procedure for Table 2 and yielding aer column chromatog- hexane ¼ 5 : 95) the pure product 3g (390 mg, 85%). A pale
1
ꢀ
raphy (ethyl acetate–hexane ¼ 15 : 85) the pure product 3c (502 yellow solid; m.p.: 147.2–147.6 C. H NMR (CDCl3, 300 MHz,
1
mg, 94%). Viscous liquid. H NMR (CDCl3, 300 MHz, ppm): d ppm): d 8.08 (d, J ¼ 8.3 Hz, 4H), 7.44 (d, J ¼ 8.3 Hz, 4H), 3.66 (t, J
8.03 (d, J ¼ 7.1 Hz, 2H), 7.46–7.62 (m, 6H), 4.26 (q, J ¼ 7.2 Hz, ¼ 7.3 Hz, 2H), 1.61–1.74 (m, 2H), 1.26–1.42 (m, 6H), 0.88 (t, J ¼
4H), 3.51 (t, J ¼ 7.2 Hz, 2H), 1.48–1.66 (m, 2H), 1.19–1.36 (m, 6.2 Hz, 3H); 13C NMR (CDCl3, 75 MHz, ppm): d 162.7, 143.5,
12H), 0.84 (t, J ¼ 6.6 Hz, 3H); 13C NMR (CDCl3, 75 MHz, ppm): d 136.3, 130.7, 129.3, 129.2, 128.8, 38.7, 31.4, 28.4, 26.6, 22.5, 14.0;
166.4, 162.6, 142.8, 131.6, 131.5, 131.23, 131.15, 130.8, 130.0, MS (EI, 70 ev): 457 (M+, 35%), 417 (18%), 386 (24%), 373 (13%),
129.5, 61.1, 38.0, 31.2, 28.2, 26.3, 22.3, 13.8; MS (EI, 70 ev): 533 57 (100%); HRMS (EI): calcd for C24H21Cl2NO2S: 457.0670%,
(M+, 35%), 85 (38%), 71 (55%), 57 (100%); HRMS (EI): calcd for found: 457.0673%.
C
30H31NO6S: 533.1872%, found: 533.1871%.
1,3-Bis(4-uorophenyl)-5-hexyl-4H-thieno[3,4-c]pyrrole-
4,40-(5-Hexyl-4,6-dioxo-5,6-dihydro-4H-thieno[3,4-c]pyrrole- 4,6(5H)-dione (3h). The title compound was prepared from 1a
1,3-diyl)dibenzonitrile (3d). The title compound was prepared (237 mg, 1.00 mmol) and 1-bromo-4-uorobenzene (2h) (438
from 1a (237 mg, 1.00 mmol) and 4-bromobenzonitrile (2d) (455 mg, 2.50 mmol) according to the general procedure for Table 2
mg, 2.50 mmol) according to the general procedure for Table 2 and yielding aer column chromatography (ethyl acetate–
and yielding aer column chromatography (ethyl acetate– hexane ¼ 2 : 98) the pure product 3h (328 mg, 77%). A white
hexane ¼ 20 : 80) the pure product 3d (409 mg, 93%). A yellow solid; m.p.: 122.8–123.1 ꢀC. 1H NMR (CDCl3, 300 MHz, ppm): d
solid; m.p.: 193.5–194.2 ꢀC. 1H NMR (CDCl3, 300 MHz, ppm): d 8.07–8.17 (m, 4H), 7.09–7.20 (m, 4H), 3.65 (t, J ¼ 7.4 Hz, 2H),
8.27 (d, J ¼ 8.5 Hz, 4H), 7.77 (d, J ¼ 8.5 Hz, 4H), 3.68 (t, J ¼ 7.3 1.60–1.73 (m, 2H), 1.26–1.40 (m, 6H), 0.88 (t, J ¼ 6.8 Hz, 3H); 13
C
1
Hz, 2H), 1.55–1.75 (m, 2H), 1.25–1.45 (m, 6H), 0.88 (t, J ¼ 6.3 Hz, NMR (CDCl3, 75 MHz, ppm): d 163.6 (d, JC,F ¼ 251 Hz), 162.7,
3H); 13C NMR (CDCl3, 75 MHz, ppm): d 162.3, 143.1, 134.0, 143.4, 130.1 (d, 3JC,F ¼ 9 Hz), 126.69, 126.65, 116.0 (d, 2JC,F ¼ 22
132.7, 128.5, 127.9, 118.1, 113.6, 38.9, 31.3, 28.3, 26.5, 22.4, 13.9; Hz), 38.6, 31.4, 28.4, 26.6, 22.5, 14.0; MS (EI, 70 ev): 425 (M+,
MS (EI, 70 ev): 439 (M+, 83%), 370 (31%), 204 (100%); HRMS 100%), 368 (8%), 354 (85%); HRMS (EI): calcd for
(EI): calcd for C26H21N3O2S: 439.1354%, found: 439.1347%.
C
24H21F2NO2S: 425.1261%, found: 425.1255%.
1,3-Bis(4-acetylphenyl)-5-hexyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-
1,3-Bis(2,4-diuorophenyl)-5-hexyl-4H-thieno[3,4-c]pyrrole-
dione (3e). The title compound was prepared from 1a (237 mg, 4,6(5H)-dione (3i). The title compound was prepared from 1a
1.00 mmol) and 4-bromoacetophenone (2e) (498 mg, 2.50 (237 mg, 1.00 mmol) and 1-bromo-2,4-diuorobenzene (2i) (483
mmol) according to the general procedure for Table 2 and mg, 2.50 mmol) according to the general procedure for Table 2
yielding aer column chromatography (ethyl acetate–hexane ¼ and yielding aer column chromatography (ethyl acetate–
20 : 80) the pure product 3e (403 mg, 85%). A yellow solid; m.p.: hexane ¼ 4 : 96) the pure product 3i (378 mg, 82%). A white
173.1–175.0 ꢀC. 1H NMR (CDCl3, 300 MHz, ppm): d 8.25 (d, J ¼ solid; m.p.: 118.4–119.7 ꢀC. 1H NMR (CDCl3, 300 MHz, ppm): d
8.4 Hz, 4H), 8.06 (d, J ¼ 8.4 Hz, 4H), 3.69 (t, J ¼ 7.2 Hz, 2H), 2.64 8.35–8.55 (m, 2H), 6.90–7.18 (m, 4H), 3.65 (t, J ¼ 7.5 Hz, 2H),
(s, 6H), 1.62–1.79 (m, 2H), 1.24–1.47 (m, 6H), 0.88 (t, J ¼ 6.5 Hz, 1.59–1.82 (m, 2H), 1.21–1.49 (m, 6H), 0.87 (t, J ¼ 6.2 Hz, 3H); 13
C
¼
3H); 13C NMR (CDCl3, 75 MHz, ppm): d 196.5, 162.0, 143.3, NMR (CDCl3, 75 MHz, ppm): d 163.7 (dd, 1JC,F ¼ 253 Hz, 3JC,F
137.5, 133.8, 131.9, 128.6, 127.8, 38.6, 31.2, 28.1, 26.40, 26.35, 12 Hz), 162.6, 159.6 (dd, 1JC,F ¼ 257 Hz, 3JC,F ¼ 16 Hz), 137.6 (dd,
22.3, 13.8; MS (EI, 70 ev): 473 (M+, 90%), 251 (100%), 238 (47%), 3JC,F ¼ 7 Hz, 3JC,F ¼ 5 Hz), 132.7 (dd, 3JC,F ¼ 10 Hz, 5JC,F ¼ 3 Hz),
223 (96%), 147 (43%); HRMS (EI): calcd for C28H27NO4S: 131.4, 114.7 (dd, 2JC,F ¼ 13 Hz, 4JC,F ¼ 4 Hz), 112.0 (dd, 2JC,F ¼ 21
4
2
473.1661%, found: 473.1659%.
Hz, JC,F ¼ 3 Hz), 104.5 (t, JC,F ¼ 26 Hz), 38.6, 31.3, 28.3, 26.5,
35874 | RSC Adv., 2014, 4, 35868–35878
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22.4, 13.9; MS (EI, 70 ev): 461 (M+, 79%), 390 (100%), 338 (58%); 26.5, 22.5, 14.0; MS (FAB): 582 ([M + 1]+, 1%), 461 (2%), 401 (2%),
HRMS (FAB): calcd for C24H19F4NO2S: 461.1073%, found: 141 (85%), 106 (100%); HRMS (FAB): calcd for C28H21F6NO4S:
461.1067%.
5-Hexyl-1,3-bis(4-(triuoromethyl)phenyl)-4H-thieno[3,4-c]-
581.1095%, found: 581.1089%.
5-Hexyl-1,3-di-p-tolyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione
pyrrole-4,6(5H)-dione (3j). The title compound was prepared (3n). The title compound was prepared from 1a (237 mg, 1.00
from 1a (237 mg, 1.00 mmol) and 4-bromobenzotriuoride (2j) mmol) and 4-bromotoluene (2q) (428 mg, 2.50 mmol) according
(563 mg, 2.50 mmol) according to the general procedure for to the general procedure for Table 2 and yielding aer column
Table 2 and yielding aer column chromatography (ethyl chromatography (ethyl acetate–hexane ¼ 2 : 98) the pure
acetate–hexane ¼ 2 : 98) the pure product 3j (321 mg, 61%). A product 3q (342 mg, 82%). A white solid; m.p.: 147.8–149.5 ꢀC.
pale yellow solid; m.p.: 101.0–102.3 ꢀC. 1H NMR (CDCl3, 300 1H NMR (CDCl3, 300 MHz, ppm): d 8.02 (d, J ¼ 8.2 Hz, 4H), 7.27
MHz, ppm): d 8.23 (d, J ¼ 8.3 Hz, 4H), 7.71 (d, J ¼ 8.3 Hz, 4H), (d, J ¼ 8.2 Hz, 4H), 3.65 (t, J ¼ 7.5 Hz, 2H), 2.40 (s, 6H), 1.61–1.76
3.64 (t, J ¼ 7.5 Hz, 2H), 1.58–1.75 (m, 2H), 1.22–1.43 (m, 6H), (m, 2H), 1.22–1.42 (m, 6H), 0.88 (t, J ¼ 6.9 Hz, 3H); 13C NMR
0.88 (t, J ¼ 7.5 Hz, 3H); 13C NMR (CDCl3, 75 MHz, ppm): d 162.1, (CDCl3, 75 MHz, ppm): d 162.9, 144.6, 140.3, 129.7, 129.4, 127.8,
2
143.0, 133.1, 132.0, 131.7 (q, JC,F ¼ 33 Hz), 128.0, 125.8, 123.6 38.4, 31.4, 28.4, 26.6, 22.5, 21.4, 14.0; MS (FAB): 418 ([M + 1]+,
1
(q, JC,F ¼ 271 Hz), 38.6, 31.2, 28.2, 26.5, 22.4, 13.8; MS (EI, 70 100%), 346 (63%), 316 (46%), 139 (42%), 106 (56%); HRMS
ev): 525 (M+, 76%), 454 (100%), 372 (49%); HRMS (EI): calcd for (FAB): calcd for C26H27NO2S: 417.1762%, found: 417.1770%.
C
26H21F6NO2S: 525.1197%, found: 525.1191%.
5-Hexyl-1,3-di-o-tolyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione
5-Hexyl-1,3-bis(2-(triuoromethyl)phenyl)-4H-thieno[3,4-c]- (3o). The title compound was prepared from 1a (237 mg, 1.00
pyrrole-4,6(5H)-dione (3k). The title compound was prepared mmol) and 2-bromotoluene (2o) (428 mg, 2.50 mmol) according
from 1a (237 mg, 1.00 mmol) and 2-bromobenzotriuoride (2k) to the general procedure for Table 2 and yielding aer column
(563 mg, 2.50 mmol) according to the general procedure for chromatography (ethyl acetate–hexane ¼ 5 : 95) the pure
Table 2 and yielding aer column chromatography (ethyl product 3o (363 mg, 87%). Viscous liquid. 1H NMR (CDCl3, 300
acetate–hexane ¼ 15 : 85) the pure product 3k (342 mg, 65%). MHz, ppm): d 7.57 (d, J ¼ 7.4 Hz, 2H), 7.25–7.44 (m, 6H), 3.64 (t,
1
Viscous liquid. H NMR (CDCl3, 300 MHz, ppm): d 7.83 (d, J ¼ J ¼ 7.3 Hz, 2H), 2.53 (s, 6H), 1.60–1.77 (m, 2H), 1.25–1.45 (m,
7.2 Hz, 2H), 7.54–7.73 (m, 6H), 3.55 (t, J ¼ 7.3 Hz, 2H), 1.55–1.69 6H), 0.91 (t, J ¼ 6.7 Hz, 3H); 13C NMR (CDCl3, 75 MHz, ppm): d
(m, 2H), 1.19–1.40 (m, 6H), 0.86 (t, J ¼ 6.6 Hz, 3H); 13C NMR 162.5, 144.2, 137.0, 131.3, 130.71, 130.65, 129.7, 129.3, 125.7,
(CDCl3, 75 MHz, ppm): d 162.0, 140.7, 132.9, 132.8, 131.6, 130.0, 38.2, 31.2, 28.2, 26.4, 22.3, 20.3, 13.8; MS (EI, 70 ev): 417 (M+,
2
3
129.7 (q, JC,F ¼ 31 Hz), 128.0, 126.6 (q, JC,F ¼ 5 Hz), 123.5 (q, 66%), 346 (51%), 81 (30%), 58 (100%); HRMS (EI): calcd for
1JC,F ¼ 272 Hz), 38.4, 31.2, 28.2, 26.4, 22.4, 13.9; MS (EI, 70 ev):
525 (M+, 56%), 454 (100%), 407 (35%), 379 (36%); HRMS (EI):
calcd for C26H21F6NO2S: 525.1197%, found: 525.1191%.
C
26H27NO2S: 417.1762%, found: 417.1754%.
1,3-Bis(3,5-dimethylphenyl)-5-hexyl-4H-thieno[3,4-c]pyrrole-
4,6(5H)-dione (3p). The title compound was prepared from 1a
1,3-Bis(3,5-bis(triuoromethyl)phenyl)-5-hexyl-4H-thieno- (237 mg, 1.00 mmol) and 1-bromo-3,5-dimethylbenzene (2p)
[3,4-c]pyrrole-4,6(5H)-dione (3l). The title compound was (463 mg, 2.50 mmol) according to the general procedure for
prepared from 1a (237 mg, 1.00 mmol) and 1-bromo-3,5- Table 2 and yielding aer column chromatography (ethyl
bis(triuoromethyl)benzene (2l) (733 mg, 2.50 mmol) accord- acetate–hexane ¼ 3 : 97) the pure product 3p (383 mg, 86%). A
ing to the general procedure for Table 2 and yielding aer pale yellow solid; m.p.: 129.9–131.4 ꢀC. 1H NMR (CDCl3, 300
column chromatography (ethyl acetate–hexane ¼ 3 : 97) the MHz, ppm): d 7.75 (s, 4H), 7.07 (s, 2H), 3.66 (t, J ¼ 6.0 Hz, 2H),
pure product 3l (628 mg, 95%). A white solid; m.p.: 170.0–170.8 2.4 (s, 12H), 1.60–1.75 (m, 2H), 1.23–1.44 (m, 6H), 0.88 (t, J ¼ 6.8
ꢀC. 1H NMR (CDCl3, 300 MHz, ppm): d 8.69 (s, 4H), 7.98 (s, 2H), Hz, 3H); 13C NMR (CDCl3, 75 MHz, ppm): d 162.9, 145.2, 138.5,
3.73 (t, J ¼ 7.5 Hz, 2H), 1.62–1.78 (m, 2H), 1.23–1.44 (m, 6H), 131.8, 130.4, 130.0, 125.8, 38.6, 31.5, 28.5, 26.6, 22.5, 21.3, 14.0;
0.89 (t, J ¼ 6.7 Hz, 3H); 13C NMR (CDCl3, 75 MHz, ppm): d 162.2, MS (FAB): 446 ([M + 1]+, 100%), 374 (41%), 344 (33%), 130 (27%);
141.6, 133.1, 132.8, (q, 2JC,F ¼ 34 Hz), 131.9, 128.1, 123.8, 122.9, HRMS (FAB): calcd for C28H31NO2S: 445.2075%, found:
1
(q, JC,F ¼ 272 Hz), 39.2, 31.4, 28.4, 26.6, 22.5, 13.9; MS (EI, 70 445.2074%.
ev): 661 (M+, 56%), 590 (100%), 257 (25%); HRMS (EI): calcd for
1,3-Bis(4-butylphenyl)-5-hexyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-
dione (3q). The title compound was prepared from 1a (237 mg,
C
28H19F12NO2S: 661.0945%, found: 661.0942%.
5-Hexyl-1,3-bis(4-(2,2,2-triuoroacetyl)phenyl)-4H-thieno- 1.00 mmol) and 1-bromo-4-butylbenzene (2q) (533 mg, 2.50
[3,4-c]pyrrole-4,6(5H)-dione (3m). The title compound was mmol) according to the general procedure for Table 2 and
prepared from 1a (237 mg, 1.00 mmol) and 40-bromo-2,2,2- yielding aer column chromatography (ethyl acetate–hexane ¼
triuoroacetophenone (2m) (557 mg, 2.20 mmol) according to 6 : 94) the pure product 3q (361 mg, 72%). A yellow solid; m.p.:
the general procedure for Table 2 and yielding aer column 64.3–65.2 ꢀC. 1H NMR (CD2Cl2, 300 MHz, ppm): d 8.02 (d, J ¼ 8.2
chromatography (ethyl acetate–hexane ¼ 30 : 70) the pure Hz, 4H), 7.26 (d, J ¼ 8.2 Hz, 4H), 3.61 (t, J ¼ 7.2 Hz, 2H), 2.66 (t, J
product 3m (320 mg, 55%). A yellow solid; m.p.: 153.0–154.9 ꢀC. ¼ 7.5 Hz, 4H), 1.58–1.77 (m, 6H), 1.27–1.51 (m, 10H), 0.86–1.08
1H NMR (CDCl3, 300 MHz, ppm): d 8.36 (d, J ¼ 8.3 Hz, 4H), 8.20 (m, 9H); 13C NMR (CD2Cl2, 75 MHz, ppm): d 163.4, 146.1, 145.0,
(d, J ¼ 8.3 Hz, 4H), 3.72 (t, J ¼ 7.2 Hz, 2H), 1.64–1.78 (m, 2H), 130.6, 129.4, 128.7, 128.5, 39.0, 36.1, 34.0, 32.1, 29.0, 27.2, 23.2,
1.27–1.43 (m, 6H), 0.89 (t, J ¼ 6.7 Hz, 3H); 13C NMR (CDCl3, 75 23.0, 14.4, 14.3; MS (EI, 70 ev): 501 (M+, 19%), 101 (36%), 87
MHz, ppm): d 179.5 (q, 2JC,F ¼ 36 Hz), 162.2, 143.3, 136.3, 133.2, (100%); HRMS (EI): calcd for C32H39NO2S: 501.2702%, found:
1
130.7, 130.6, 128.5, 116.5 (q, JC,F ¼ 289 Hz), 39.0, 31.3, 28.3, 501.2703%.
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5-Hexyl-1,3-bis(4-methoxyphenyl)-4H-thieno[3,4-c]pyrrole- General procedure for Table 3
4,6(5H)-dione (3r). The title compound was prepared from 1a
To a solution of Pd(OAc)2 (10 mol%), P(m-tolyl)3 (20 mol%), and
Cs2CO3 (2.40 mmol) in toluene (3 mL) in a ame-dried Schlenk
tube (20 mL) were added TPD 1b or FPD 1c (1.00 mmol) and the
corresponding aryl bromides (2.50 mmol) under N2. The reac-
tion mixture was then heated at 110 ꢀC under N2 for 24 h. Aer
the reaction mixture had cooled to room temperature, water
(10 mL) was added. The mixture was extracted with ethyl acetate
(2 ꢂ 30 mL), and the combined organic layers were washed with
brine (50 mL), dried (Na2SO4) and concentrated in vacuo. Puri-
cation by ash chromatography (ethyl acetate–hexane) yielded
the desired products 4a–d, 5a–b.
Diethyl 4,40-(5-(2-ethylhexyl)-4,6-dioxo-5,6-dihydro-4H-thieno-
[3,4-c]pyrrole-1,3-diyl) dibenzoate (4a). The title compound was
prepared from 1b (265 mg, 1.00 mmol) and ethyl 4-bromo-
benzoate (2b) (573 mg, 2.50 mmol) according to the general
procedure for Table 3 and yielding aer column chromatog-
raphy (ethyl acetate–hexane ¼ 10 : 90) the pure product 4a
(477 mg, 85%). A pale yellow solid; m.p.: 140.6–142.6 ꢀC. 1H
NMR (CDCl3, 300 MHz, ppm): d 8.17 (d, J ¼ 8.4 Hz, 4H), 8.09 (d,
J ¼ 8.4 Hz, 4H), 4.38 (q, J ¼ 7.1 Hz, 4H), 3.54 (d, J ¼ 7.2 Hz, 2H),
1.75–1.89 (m, 1H), 1.18–1.49 (m, 14H), 0.82–0.98 (m, 6H); 13C
NMR (CDCl3, 75 MHz, ppm): d 165.5, 162.6, 143.6, 134.0, 131.7,
131.4, 129.9, 127.8, 61.1, 42.5, 38.2, 30.5, 28.4, 23.8, 22.9, 14.2,
14.0, 10.3; MS (EI, 70 ev): 561 (M+, 69%), 462 (63%), 449 (45%),
390 (34%), 57 (100%); HRMS (EI): calcd for C32H35NO6S:
561.2185%, found: 561.2181%.
(237 mg, 1.00 mmol) and 4-bromoanisole (2r) (468 mg, 2.50
mmol) according to the general procedure for Table 2 and
yielding aer column chromatography (ethyl acetate–hexane ¼
6 : 94) the pure product 3r (288 mg, 64%). A pale yellow solid;
m.p.: 135.5–136.0 ꢀC. 1H NMR (CDCl3, 300 MHz, ppm): d 8.09 (d,
J ¼ 8.9 Hz, 4H), 6.97 (d, J ¼ 8.9 Hz, 4H), 3.86 (s, 6H), 3.64 (t, J ¼
7.4 Hz, 2H), 1.60–1.72 (m, 2H), 1.20–1.45 (m, 6H), 0.88 (t, J ¼ 6.6
Hz, 3H); 13C NMR (CDCl3, 75 MHz, ppm): d 163.1, 160.9, 144.2,
129.6, 128.8, 123.5, 114.2, 55.4, 38.5, 31.4, 28.4, 26.6, 22.5, 14.0;
MS (EI, 70 ev): 449 (M+, 100%), 418 (3%), 378 (26%); HRMS (EI):
calcd for C26H27NO4S: 449.1661%, found: 449.1665%.
5-Hexyl-1,3-bis(2-methoxyphenyl)-4H-thieno[3,4-c]pyrrole-
4,6(5H)-dione (3s). The title compound was prepared from 1a
(237 mg, 1.00 mmol) and 2-bromoanisole (2s) (468 mg, 2.50
mmol) according to the general procedure for Table 2 and
yielding aer column chromatography (ethyl acetate–hexane ¼
1
15 : 85) the pure product 3s (360 mg, 80%). Viscous liquid. H
NMR (CDCl3, 300 MHz, ppm): d 8.32 (dd, J ¼ 7.8, 1.6 Hz, 2H),
7.32–7.44 (m, 2H), 7.10 (t, J ¼ 8.0 Hz, 2H), 7.00 (d, J ¼ 8.0 Hz,
2H), 3.91 (s, 6H), 3.65 (t, J ¼ 7.2 Hz, 6H), 1.60–1.75 (m, 2H), 1.24–
1.41 (m, 6H), 0.89 (t, J ¼ 6.8 Hz, 3H); 13C NMR (CDCl3, 75 MHz,
ppm): d 163.1, 156.0, 141.2, 131.3, 130.8, 130.2, 120.6, 119.7,
111.1, 55.4, 38.1, 31.3, 28.3, 26.5, 22.4, 13.9; MS (EI, 70 ev): 449
(M+, 100%), 417 (6%), 378 (35%); HRMS (EI): calcd for
C
26H27NO4S: 449.1661%, found: 449.1663%.
1,3-Bis(4-(diphenylamino)phenyl)-5-hexyl-4H-thieno[3,4-c]-
5-(2-Ethylhexyl)-1,3-bis(4-(triuoromethyl)phenyl)-4H-thieno-
[3,4-c]pyrrole-4,6(5H)-dione (4b). The title compound was
prepared from 1b (265 mg, 1.00 mmol) and 4-bromobenzotri-
uoride (2j) (563 mg, 2.50 mmol) according to the general
procedure for Table 3 and yielding aer column chromatog-
raphy (ethyl acetate–hexane ¼ 1 : 99) the pure product 4b (354
pyrrole-4,6(5H)-dione (3t). The title compound was prepared
from 1a (237 mg, 1.00 mmol) and 4-bromotriphenylamine (2t)
(811 mg, 2.50 mmol) according to the general procedure for
Table 2 and yielding aer column chromatography (ethyl
acetate–hexane ¼ 4 : 96) the pure product 3t (478 mg, 66%). A
1
ꢀ
yellow solid; m.p.: 148.6–149.9 C. H NMR (CDCl3, 300 MHz,
ppm): d 7.97–8.05 (m, 4H), 7.27–7.38 (m, 8H), 7.00–7.23 (m,
16H), 3.64 (t, J ¼ 7.2 Hz, 2H), 1.60–1.74 (m, 2H), 1.21–1.45 (m,
6H), 0.89 (t, J ¼ 6.7 Hz, 3H); 13C NMR (CDCl3, 75 MHz, ppm): d
163.2, 149.4, 146.9, 144.2, 129.5, 129.1, 128.8, 125.4, 124.0,
123.8, 121.5, 38.5, 31.5, 28.5, 26.7, 22.5, 14.1; MS (FAB): 723 (M+,
100%), 141 (60%), 106 (90%); HRMS (FAB): calcd for
1
mg, 64%). A pale yellow solid; m.p.: 101.5–102.6 ꢀC. H NMR
(CDCl3, 300 MHz, ppm): d 8.25 (d, J ¼ 8.4 Hz, 4H), 7.74 (d, J ¼ 8.4
Hz, 4H), 3.57 (d, J ¼ 7.2 Hz, 2H), 1.75–1.93 (m, 1H), 1.20–1.44
(m, 8H), 0.83–0.98 (m, 6H); 13C NMR (CDCl3, 75 MHz, ppm): d
2
162.7, 143.3, 133.4, 132.0, 131.9 (q, JC,F ¼ 32 Hz), 128.3, 126.0
(q, 3JC,F ¼ 4 Hz), 123.7 (q, 1JC,F ¼ 271 Hz), 42.7, 38.3, 30.6, 28.6,
23.9, 23.0, 14.0, 10.4; MS (FAB): 554 ([M + 1]+, 67%), 534 (28%),
454 (100%), 424 (38%); HRMS (FAB): calcd for C28H25F6NO2S:
553.1510%, found: 553.1512%.
C
48H41N3O2S: 723.2919%, found: 723.2928%.
1-(1,2-Dihydropyren-1-yl)-3-(8,10-dihydropyren-1-yl)-5-hexyl-
4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (3u). The title compound
was prepared from 1a (237 mg, 1.00 mmol) and 1-bromopyrene
(2u) (703 mg, 2.50 mmol) according to the general procedure for
Table 2 and yielding aer column chromatography (dichloro-
methane–hexane ¼ 30 : 70) the pure product 3u (453 mg, 71%).
A yellow solid; m.p.: 235.0–236.5 ꢀC. 1H NMR (CDCl3, 300 MHz,
ppm): d 8.55 (d, J ¼ 9.2 Hz, 2H), 7.96–8.49 (m, 16H), 3.66 (t, J ¼
7.5 Hz, 2H), 1.60–1.82 (m, 2H), 1.15–1.50 (m, 6H), 0.85 (t, J ¼ 6.6
Hz, 3H); 13C NMR (CDCl3, 75 MHz, ppm): d 162.7, 144.6, 132.6,
132.5, 131.2, 130.8, 129.2, 128.8, 128.7, 128.6, 127.2, 126.3,
126.0, 125.8, 124.9, 124.6, 124.49, 124.46, 124.2, 38.5, 31.3, 28.4,
26.6, 22.5, 14.0; MS (FAB): 637 (M+, 3%), 537 (2%), 141 (95%),
106 (100%); HRMS (FAB): calcd for C44H31NO2S: 637.2075%,
found: 637.2079%.
5-(2-Ethylhexyl)-1,3-di-p-tolyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-
dione (4c). The title compound was prepared from 1b (265 mg,
1.00 mmol) and 4-bromotoluene (2n) (428 mg, 2.50 mmol)
according to the general procedure for Table 3 and yielding aer
column chromatography (ethyl acetate–hexane ¼ 5 : 95) the
pure product 4c (241 mg, 54%). A white solid; m.p.: 121.1–122.4
ꢀC. 1H NMR (CD2Cl2, 300 MHz, ppm): d 8.01 (d, J ¼ 7.8 Hz, 4H),
7.26 (d, J ¼ 7.8 Hz, 4H), 3.50 (d, J ¼ 7.0 Hz, 2H), 2.39 (s, 6H),
1.73–1.87 (m, 1H), 1.22–1.46 (m, 8H), 0.84–1.00 (m, 6H); 13C
NMR (CD2Cl2, 75 MHz, ppm): d 163.6, 144.9, 141.0, 130.4, 130.0,
128.5, 42.7, 38.9, 31.2, 29.2, 24.5, 23.6, 21.8, 14.5, 10.9; MS (EI,
70 ev): 445 (M+, 63%), 346 (72%), 333 (941%), 84 (100%); HRMS
(EI): calcd for C28H31NO2S: 445.2075%, found: 445.2080%.
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1,3-Bis(4-(diphenylamino)phenyl)-5-(2-ethylhexyl)-4H-thieno-
RSC Advances
(m, 2H), 1.22–1.45 (m, 6H), 0.89 (t, J ¼ 6.5 Hz, 3H); 13C NMR
(CDCl3, 75 MHz, ppm): d 162.3, 158.1, 143.3, 135.4, 133.2, 132.1,
131.3, 129.0, 113.4, 112.4, 84.0, 39.0, 31.3, 28.3, 26.6, 22.5, 14.0;
MS (EI, 70 ev): 542 ([M + 1]+, 100%), 493 (99%), 470 (83%), 423
[3,4-c]pyrrole-4,6(5H)-dione (4d). The title compound was
prepared from 1b (237 mg, 1.00 mmol) and 4-bromotriphenyl-
amine (2t) (811 mg, 2.50 mmol) according to the general
procedure for Table 3 and yielding aer column chromatog-
raphy (ethyl acetate–hexane ¼ 5 : 95) the pure product 4d (383
mg, 51%). An orange solid; m.p.: 176.7–178.7 ꢀC. 1H NMR
(CDCl3, 300 MHz, ppm): d 7.95–8.05 (m, 4H), 7.27–7.40 (m, 8H),
7.00–7.23 (m, 16H), 3.54 (d, J ¼ 7.2 Hz, 2H), 1.75–1.91 (m, 1H),
1.25–1.40 (m, 8H), 0.82–0.98 (m, 6H); 13C NMR (CDCl3, 75 MHz,
ppm): d 163.4, 149.3, 146.8, 144.1, 129.4, 129.0, 128.6, 125.4,
124.0, 123.7, 121.4, 42.4, 38.2, 30.6, 28.6, 23.9, 23.0, 14.1, 10.5;
MS (FAB): 751 (M+, 100%); HRMS (FAB): calcd for C50H45N3O2S:
751.3232%, found: 751.3227%.
(91%), 422 (77%); HRMS (EI): calcd for
541.1572%, found: 541.1567%.
C32H23N5O2S:
Acknowledgements
Financial support provided by the Ministry of Science and
Technology (MOST), Taiwan (NSC 101-2113-M-008-007-MY2)
and the National Central University are gratefully
acknowledged.
5-Hexyl-1,3-diphenyl-4H-furo[3,4-c]pyrrole-4,6(5H)-dione (5a).
The title compound was prepared from 1c (221 mg, 1.00 mmol)
and bromobenzene (2a) (393 mg, 2.50 mmol) according to the
general procedure for Table 3 and yielding aer column chro-
matography (ethyl acetate–hexane ¼ 5 : 95) the pure product 5a
(336 mg, 90%). A white solid; m.p.: 114.9–115.1 ꢀC. 1H NMR
(CDCl3, 300 MHz, ppm): d 8.11 (dd, J ¼ 7.9, 1.5 Hz, 4H), 7.32–
7.47 (m, 6H), 3.58 (t, J ¼ 6.0 Hz, 2H), 1.60–1.72 (m, 2H), 1.23–
1.45 (m, 6H), 0.90 (t, J ¼ 6.4 Hz, 3H); 13C NMR (CDCl3, 75
MHz,ppm): d 161.9, 149.0, 130.1, 128.6, 127.1, 127.7, 117.2, 38.5,
31.2, 28.2, 26.4, 22.4, 13.9; MS (FAB): 374 ([M + 1]+, 100%), 302
(40%), 272 (45%), 63 (82%); HRMS (FAB): calcd for C24H23NO3:
373.1678%, found: 373.1680%.
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