Synthesis of some new bis-(p-fluorophenyl)amides of the thieno[3,2-b]thiophene, thieno[3,2-b]furan and 1,2-bis{5-[2-(2-thienyl)ethenyl] 2-thienyl}ethene series

Article abstract of DOI:10.3390/71200871

Three new heterocyclic substituted dianilides, namely 3-chloro-5-[1-(p- fluorophenylcarbamoyl)-2-(2-thienyl)ethenyl]thieno-[3,2-b]thiophene-2-carboxy-p- fluoroanilide (8), 1,2-bis{5-[2-(p-fluorophenylcarbamoyl)-2-(2-thienyl)ethenyl]- 2-thienyl}ethene (13) and 6-chloro-2-{2-[3-chloro-2-(p-fluorophenyl-carbamoyl)- 5-thieno[3,2-b]thienyl]-2-ethoxycarbonylethenyl}thieno[3,2-b] furan-5-carboxy-p-fluoroanilide (20) were prepared by multistep synthesis. The prepared dianilides are of particular interest for their potential to serve as the planar heteroaromatic core of DNA intercalators or groove binders.

Full text of DOI:10.3390/71200871

Molecules 2002, 7, 871-884
molecules
ISSN 1420-3049
http://www.mdpi.org
Synthesis of Some New bis-(p-Fluorophenyl)amides of the
Thieno[3,2-b]thiophene, Thieno[3,2-b]furan and 1,2-bis{5-[2-(2-
Thienyl)ethenyl]2-thienyl}ethene Series
Davorka Pavlicic1, Jasna Dogan Koružnjak1, Zrinka Banic-Tomišic1 and Grace Karminski-
Zamola2,
*
1
"Pliva" d.d., Research and Development, Prilaz baruna Filipovica 25, 10000 Zagreb, Croatia.
Department of Organic Chemistry, Faculty of Chemical Engineering and Technology, University of
2
Zagreb, Marulicev trg 20, 10000 Zagreb, Croatia.
*Author to whom correspondence should be addressed; e-mail gzamola@pierre.fkit.hr
Received: 13 August 2002; in revised form: 28 November 2002 / Accepted: 4 December 2002 /
Published: 31 December 2002
Abstract: Three new heterocyclic substituted dianilides, namely 3-chloro-5-[1-(p-
fluorophenylcarbamoyl)-2-(2-thienyl)ethenyl]thieno-[3,2-b]thiophene-2-carboxy-p-fluoro-
anilide
(13)
(8),
and
1,2-bis{5-[2-(p-fluorophenylcarbamoyl)-2-(2-thienyl)ethenyl]-2-thienyl}ethene
6-chloro-2-{2-[3-chloro-2-(p-fluorophenyl-carbamoyl)-5-thieno[3,2-b]thienyl]-2-
ethoxycarbonylethenyl}thieno[3,2-b]furan-5-carboxy-p-fluoroanilide (20) were prepared by
multistep synthesis. The prepared dianilides are of particular interest for their potential to
serve as the planar heteroaromatic core of DNA intercalators or groove binders.
Keywords: Amides, thieno[3,2-b]thienyl- series, potential intercalators or groove binders.
Introduction
There is little recent literature data on the thieno[3,2-b]- or thieno[3,4-b]thiophenes with different
features [1-3] and applications [4,5]. For example, the new class of thienothiophenes, some of which
are available from monobromo-, dibromo- or tribromothiophenes [6], was recently described [7].
3,6-Dimethylthieno[3,2-b]thiophene, prepared as the monomer for a polymerization process [8-9], or

Molecules 2002, 7
872
thieno[3,2-b]thiophenes which are synthesized from phthalimido sulfenyl chloride upon reaction with
diaryl (or heteroaryl) acetylenes [10] or as intermediates in the synthesis of heteroarenes which are
isoelectric with perylene [11] and various thieno[3,2-c]-anellated 1,2-dithiins prepared from
appropriate thiophene precursors [12] are also known. The corresponding dianilides of the thieno[3,2-
b]thiophene and thieno[3,2-b]furan types are however unknown. On the other hand, there is patent
literature that describes the synthesis of thiophene-3,4-carboxamide derivatives and their application as
dopamine receptor blockers [13] or herbicides [14]. Some substituted benzo[b]thiophene-
carboxamides are used as inhibitors of neutrophil-endothelial cell adhesion [15].
Results and Discussion
In our previous papers we have reported the synthesis and the photochemistry of some
heteropolycyclic anilides of the naphthothieno[3,2-b]thiophene series [16], dianilides of the
benzo[b]thiophene, thieno[2,3-b]thiophene [17], benzo[1,2-b:4,5-b']dithiophene and dithieno[3,2-
b:2',3'-d]thiophene series [18], and their photochemical reactions leading to the corresponding
quinolones. In this paper we describe the synthesis of the dianilides 8, 13 and 20, which are interesting
polycondensed heteroaromatic compounds as well as potential planar aromatic core of DNA
intercalators [20-22].
Dianilides 8 and 13 were prepared in the several steps from (Z)-2,3-di-(2-thienyl)acrylic acid (1,
Scheme 1). Vilsmeier formylation [23] of the methyl ester 3 of acrylic acid 1 afforded methyl Z-2-(5-
formyl-2-thienyl)-3-(2-thienyl)acrylate (4) in 69% yield [16]. Condensation of compound 4 with
malonic acid followed by hydrolysis of the ester group afforded 3-{5-[2-(2-thienyl)-1-
}
carboxy]ethenyl -2-(2-thienyl)acrylic acid (6) [16]. Treatment of 6 with thionyl chloride and pyridine
[24] provided 3-chloro-5-[1-chlorocarbonyl-2-(2-thienyl)ethenyl]thieno[3,2-b]thiophene-2-carbonyl
chloride (7). The reaction of the chloride 7 with p-fluoroaniline in chloroform gave 3-chloro-5-[1-(p-
fluorophenylcarbamoyl)-2-(2-thienyl)ethenyl]thieno[3,2-b]thiophene-2-carboxy-p-fluoroanilide
(8)
in
34% yield [16,17].
Compound 1 was decarboxylated [25] to 1,2-di-(2-thienyl)ethene (9) and formylated by the
Vilsmeier method to afford 1,2-di-[(5-formyl)-2-(2-thienyl)]ethene (10) in 42.3% yield. Reaction of
compound 10 with 2-thienylacetic acid [26] gave (Z)-1,2-bis{5-[2-carboxy-2-(2-thienyl)ethenyl]-2-(2-
thienyl)}ethene (11), as dark red crystals, in about 30 % yield. The geometry of the molecule was
determined from 1H-NMR data. The corresponding dianilide, (Z)-1,2-bis{5-[2-(p-fluorophenyl-
carbamoyl)-2-(2-thienyl)ethenyl]-2-thienyl}ethene (13), was prepared in this manner in over 56%
yield.

Molecules 2002, 7
873
Scheme 1

Molecules 2002, 7
The dianilide
874
6-chloro-2-{2-[3-chloro-2-(p-fluorophenylcarbamoyl)-5-thieno[3,2-b]thienyl]-2-
ethoxycarbonylethenyl}thieno[3,2-b]furan-5-carboxy-p-fluoroanilide (20), was prepared in several
steps. Furan-2-carboxaldehyde reacted with 2-thiopheneacetic acid to give a mixture of the (E)- and
(Z)-3-(2-furyl)-2-(2-thienyl)acrylic acids (14) and (15) [27]. The (Z)-isomer 15 was converted into the
corresponding methyl ester 16 which was formylated to give ethyl (Z)-3-[5-formyl-(2-furyl)]-2-[5-
formyl-(2-thienyl)]acrylate (17). Dialdehyde 17 was converted to the corresponding diacrylic acid-
ester, ethyl (Z)-3-[5-(2-carboxy)ethenyl-2-furyl)]-2-[5-(2-carboxy-ethenyl)-(2-thienyl)]acrylate (18)
upon reaction with malonic acid. The yield was 41%. A double cyclization with SOCl2 in the presence
of the catalytic amount of pyridine afforded 3-chloro-5-{2-ethoxycarbonyl-2-[3'-chlorocarbonyl-5'-
thieno[3,2-b]thienyl]ethenyl}thieno[3,2-b]furancarbonyl chloride (19) in 35% yield, which was
successfully converted into the corresponding dianilide 20 in 50% yield (Scheme 2).
Scheme 2

Molecules 2002, 7
875
1
The structures of all new compounds were confirmed by H-NMR, 13C-NMR, IR spectra,
elemental analysis and, in the case of compound 5, its X-ray crystal structure was also determined
(Figures 1 and 2) [28].
Figure 1. X-Ray structure of the 3-{5-[1-methoxycarbonyl-2-(2-
thienyl)ethenyl]-2-thienyl}acrylic acid (5)
Figure 2. X-Ray structure of 3-{5-[1-methoxycarbonyl-2-(2-thienyl)-ethenyl]-2-
thienyl}acrylic acid (5) bonded into dimers via H-bonding

Molecules 2002, 7
876
Acknowledgements
The authors wish to express their gratitude to PLIVA - Research and Development and to the
Ministry of Science and Technology of Croatia for financial support of this research under project no.
125005. We are also thankful to the Department of Inorganic Chemistry, Faculty of Mathematics and
Natural Sciences, University of Zagreb, for the crystallographic measurements.
Experimental
General
Melting points were determined on a Koffler hot stage microscope and are uncorrected. IR spectra
were recorded on a PERKIN-ELMER Model 257 spectrophotometer in KBr discs or as liquid films
1
between sodium chloride plates. H-NMR (300 MHz) and 13C-NMR (75.46 MHz) spectra were
recorded for CDCl or DMSO-d6 solutions with TMS as internal standard on a Varian Gemini 300.
3
spectrometer. Mass spectra were recorded on a Shimadzu QP-5000 GC/MS instrument at 70 eV using
a direct inlet system and with an ion source temperature of 300°C.
(E)- and (Z)-2,3-di-(2-thienyl)acrylic acids (1) and (2) [23].
Compounds 1 and 2 were prepared by heating 2-thienylcarboxaldehyde (23.8 g, 0.21 mol) and
thiopheneacetic acid (30 g, 0.21 mol) in triethylamine (31.5 mL) and acetic acid anhydride (31.5 mL)
for 1.5 h. After the reaction was complete, the mixture was cooled, acidified with (1:1) conc.
hydrochloric acid-water and the two isomers were extracted with ether (350 mL). The organic layer
was washed with water and the acids were extracted into 7.5% sodium carbonate solution (1000 mL).
The hot alkaline solution of sodium salts was boiled with charcoal, filtered, cooled and acidified to pH
5 with acetic acid. The precipitated (Z)- isomer 1 was filtered off and recrystallized from methanol.
The yield was 28.10 g, (58.00%), mp 236-239°C (lit. [18], mp 240-241°C). Concentrated hydrochloric
acid was added to the filtrate and additional crystalline crops consisting of the (E)-isomer 2 were thus
obtained. The yield of isomer 2 was 4.5 g (9.02 %), mp 174-175°C (lit.[23] mp 174.5-175.5°C).
Methyl (Z)-2,3-di-(2-thienyl)acrylate (3) [23, 26].
Methyl ester 3 was prepared by refluxing 1 (13 g, 0.055 mol) dissolved in absolute methanol (570
mL) and conc. sulphuric acid (2 mL) for 15 h. The volume of the cooled reaction mixture was reduced
to 200 mL and the content was poured into crushed ice (700 g). Crystalline crops were recrystallized
from methanol. White crystals (11.3 g, 82.00 %), mp 76-77°C were obtained (lit.[23] mp 75-78.5°C).

Molecules 2002, 7
877
Methyl (Z)-2-(5-formyl-2-thienyl)-3-(2-thienyl)acrylate(4) [23]
Methyl ester 3 was formylated by the Vilsmeier method. Phosphorus oxychloride (20.80 mL, 0.227
mol) was added dropwise to a cooled solution of methyl ester 3 (10.80 g, 0.043 mol) in DMF (19.00
mL, 0.246 mol) at such a rate that the temperature of the reaction mixture did not exceed 10°C. After
the addition was complete, the mixture was stirred for 1 h at room temperature, then heated at 90-95°C
for 1.5 h, cooled and poured into crushed ice (500 g), made weakly alkaline with conc. sodium
hydroxide solution and left overnight on ice. The gummy product collected was washed with water
and recrystallized from (2:3) benzene-hexane. A yellow crystalline product (8.3 g, 69.10 %) was thus
obtained, mp 137-139°C (lit.[23] 141-142°C); 13C-NMR (CDCl ) (d ppm): 52.5, 119.5, 137.8, 144.7,
3
145.4, 165.8, 184.4.
3-{5-[1-methoxycarbonyl-2-(2-thienyl)ethenyl]-2-thienyl}acrylic acid (5) [18]
Compound 5 was prepared by the condensation of formylated ester 4 (5.00 g, 0.018 mol) with
malonic acid (1.9 g, 0.002 mol) in pyridine (60 mL) to which a catalytic amount (a few drops) of
piperidine was added. The reaction mixture was heated for 2 h at 45-50°C and for 2.5 h at 100°C.
After cooling, the reaction mixture was poured into ice (500 g) and acidified with (1:1) conc.
hydrochloric acid-water (130 mL). The yellow crystals formed were filtered off and recrystallized
-1
from (2:1) ethanol-dioxane to give 2.9 g (50.40%) of the title compound, mp 196-199°C; IR (cm )
1
(KBr): 1705 (COOCH3), 1660 (COOH), 1600 (C=C); H-NMR (DMSO-d6) (d ppm): 3.96 (3H, s,
CH3), 6.20 (1H, d, J = 15.63 Hz, Hethylenic), 7.04 (1H, d, J = 3.36 Hz, Hd), 7.09 (1H, ABsyst., J = 3.37
Hz, J = 5.07 Hz, He), 7.56 (1H, d, J = 3.47 Hz, H ), 7.62 (1H, d, J = 3.48 Hz, Ha), 7.76 (1H, d, J = 5.07
b
Hz, H), 7.77 (1H, d, J = 15.63 Hz, Hethylenic), 8.22 (1H, s, Hc); 13C-NMR (DMSO-d6) (d ppm): 52.5,
f
118.1, 120.0, 127.3, 130.8, 132.3, 141.4, 166.1, 167.3. Anal. Calcd. for C15H12O4S2 C, 56.23; H, 3.75;
:
S, 20.03%; Found: C, 56.65; H, 3.96; S, 20.49%.
3-{5-[2-(2-thienyl)-1-carboxy]ethenyl}-2-(2-thienyl)acrylic acid (6)
Diacid 6 was prepared by hydrolysis of 5 (2.00 g, 0.006 mol) which was added to the solution of
10% NaOH (30 mL) and methanol (30 mL) and refluxed for 2.5 h. Methanol was distilled off in
vacuo, the residue dissolved in water, acidified with 10% hydrochloric acid and the crude product was
-
recrystallized from (1:1) ethanol-dioxane [16]. The yield was 1.85 g (96.70%), mp 232-235°C; IR (cm
1) (KBr): 1600 (C=C), 1620 (C=C), 1670 (COOH), 1690 (COOH). 1H-NMR (DMSO-d6) (d ppm): 5.94
(1H, d, J = 15.8 Hz, Hethylenic) 7.04 (1H, d, J = 3.36 Hz, Hd), 7.20 (1H, ABsyst., J = 3.36 Hz, J = 5.12
,
Hz, H), 7.44 (1H, d, J = 3.90 Hz, H , 7.52 (1H, d, J = 3.97 Hz, H), 7.58 (1H, d, J = 15.9 Hz,
e
a
b
)
Hethylenic), 7.80 (1H, d, J = 5.12 Hz, H ), 8.09 (1H, s, Hc); 13C-NMR (DMSO-d6) (d ppm): 119.1, 128.0,
f
140.3, 143.7, 167.1, 167.6. Anal. Calcd. for: C H10O4S2: C, 54.88; H, 3.27; S, 20.95%; Found: C,
14
54.59; H, 3.07; S, 21.40%.

Molecules 2002, 7
878
3-Chloro-5-[1-chlorocarbonyl-2-(2-thienyl)ethenyl]thieno[3,2-b]thiophene-2-carbonylchloride (7)
Compound 6 (1.00 g, 0.003 mol) was suspended in thionyl chloride (20 mL, 0.275 mol). The
mixture was stirred for 15 min. under external cooling by ice. To this mixture was added dropwise
pyridine (1 mL) in SOCl (1 mL). The reaction mixture was stirred for 0.5 h at room temperature and
2
for 45 h at 80-90°C. Excess thionyl chloride was removed under reduced pressure and the remaining
material was extracted with hot hexane (20 mL) to give an oily product (0.54 g, 45%) which was used
in the next step without further purification.
3-Chloro-5-[1-(p-fluorophenylcarbamoyl)-2-(2-thienyl)ethenyl]thieno[3,2-b]thiophene-2-carboxy-
p-fluoroanilide (8)
One equivalent of p-fluoroaniline (0.0013 mol) dissolved in chloroform (5 mL) and triethylamine
(5 mL) was added dropwise under stirring at room temperature to a solution of dichloride 7 (0.5 g,
0.0013 mol) in chloroform (5 mL) The reaction mixture was refluxed for 1 h. After cooling the
p-fluoroaniline hydrochloride formed was filtered off, the filtrate was concentrated in vacuo, the
residue suspended in toluene and the resulting crystals were recrystallized from N,N-
dimethylformamide [9-10]. Dianilide 8 (0.27 g, 34.10% yield) was thus obtained, mp 252-253°C; IR
1
(cm-1) (KBr): 1615 (C=C), 1660 (CONH), 3400 (NH); H-NMR (DMSO-d6) (d ppm): 7.10 (1H,
ABsyst., J = 4.76 Hz, J = 3.67 Hz, Hd), 7.15-7.21 (4 H, m, Harom.), 7.48 (1H, d, J = 3.67 Hz, H ), 7.64-
c
7.75 (4H, m, Harom), 7.71 (1H, J = 4.27 Hz, H ), 7.82 (1H, s, H ), 7.96 (1H, s, Hb), 9.85 (1H, s, NH),
e
a
10.30 (1H, s, NH); 13C-NMR (DMSO-d6) (d ppm): 115.0, 115.7 131.0, 134.3, 135.2, 135.7, 142.4,
156.7, 157.1, 159.8, 162.5, 163.1, 164.9; MS (m/z): 556 (M+), 382, 205, 177. Anal. Calcd. for:
C26H15O2ClF2N2S3: C, 56.05; H, 2.69; N, 5.05; S, 17.28%; Found: C, 56.35; H, 2.32; N, 4.91; S,
17.60%.
(Z)-1,2-di-(2-thienyl)ethene (9)
Decarboxylation of the corresponding acid 1 (10.00 g, 0.042 mol) was accomplished by a method
described earlier [25], by heating with Cu-powder (10 g) in boiling quinoline (50 mL, dried over
molecular sieves) for 1 h. The reaction mixture was taken up in ether (100 mL) and washed with 10%
hydrochloric acid (150 mL). All etheral extracts were collected, washed with water, 10% hydrochloric
acid, then with water and dried over magnesium sulphate. The residue left after the ether was
evaporated, was suspended in methanol (50 mL) and the precipitate filtered. Yellow crystals (4.8 g,
1
59.00%), mp 130-132°C were thus obtained (lit.[29] mp 133-134°C); H-NMR (CDCl ) (d ppm): 6.98
3
(1H, ABsyst., J = 5.05 Hz, J = 3.65 Hz, H or H ), 7.03 (1H, d, J = 3.65 Hz, Hc or H), 7.05 (1H, s,
b
g
f
Hethylenic), 7.17 (1H, d, J = 5.05 Hz, Ha or Hh).

Molecules 2002, 7
879
(Z)-1,2-di-[5-formyl-2-(2-thienyl)]ethene (10)
Compound 10 was prepared in the same way as 4, starting from 9 (5.00 g, 0.026 mol) in DMF
(17.5 mL) to which a mixture of POCl (18.5 mL, 0.202 mol) and DMF (17.5 mL) was added
3
dropwise under stirring and cooling,. The crude product was recrystallized from chloroform. The yield
was 2.75 g (42.30%), mp 210-212°C; IR (cm-1) (KBr): 1640 (COH), 1660 (COH); 1H-NMR (CDCl3)
(d ppm): 7.22 (1H, d, J = 3.93 Hz, Hb), 7.26 (1H, s, Hethylenic), 7.69 (1H, d, J = 3.93 Hz, Ha), 9.94 (1H,
s, CHO); 13C-NMR (CDCl ) (d ppm): 124.6, 129.0, 138.5, 142.5, 149.8 183.9; Anal. Calcd. for:
3
C12H8O2S2: C, 58.49; H, 3.22; S, 25.84%; Found: C, 58.52; H, 3.48; S, 26.12%.
(Z)-1,2-bis{5-[2-carboxy-2-(2-thienyl)ethenyl]-2-thienyl}ethene (11)
Compound 11 was prepared in same way as 1, using dialdehyde 10 (5.2 g, 0.002 mol) and
2-thiopheneacetic acid (6.3 g, 0.0044 mol) in acetic anhydride (30 mL) and triethylamine (30 mL)
[16]. Red crystals (3.2 g, 30.8% yield) were obtained after recrystalization from DMF, mp 254-257°C;
1
IR (cm-1) (KBr): 1590 (C=C), 1670 (COOH); H-NMR (DMSO-d6) (d ppm): 6.85 (1H, s, H), 7.02
g
(1H, d, J = 3.66 Hz, Hc), 7.18 (1H, ABsyst., J = 3.36 Hz, J = 3.67 Hz, Hb), 7.22 (1H, d, J = 3.97 Hz, He),
13
7.42 (1H, J = 3.96 Hz, Hf), 7.76 (1H, d, J = 3.67 Hz, Ha), 8.04 (1H, s, H ); C-NMR (DMSO-d6) (d
d
ppm): 127.3, 127.8, 132.8, 140.3, 140.8, 141.6, 142.6, 151.5, 172.8; Anal. Calcd. for: C24H16O4S4: C,
58.03; H, 3.22; S, 25.84%; Found: C, 57.85; H, 3.53; S, 26.04%.
(Z)-{5,5'-di-[2-(2-thienyl)-2-chlorocarbonylethenyl]}-1,2-di-(2-thienyl)ethene (12)
Dichloride 12 was prepared from diacid 11 (19 g, 0.20 mol) and SOCl (5 mL, 0.07 mol) dissolved
2
in dry toluene (15 mL). The mixture was stirred 30 min. at room temperature and then 2 h at 70°C.
Excess SOCl was removed under reduced pressure. The residue was extracted with hexane (50 mL)
2
and dried over magnesium sulphate. After evaporation of the solvent an oily product was obtained
-1
which was used without further purification in the next step; IR (cm ) (KBr): 1740 (COCl), 1590
(C=C).
(Z)-1,2-bis{5-[2-(p-fluorophenylcarbamoyl)-2-(2-thienyl)ethenyl]-2-thienyl}ethene (13)
p-Fluoroaniline (0.36 g, 3.2 mmol) dissolved in chloroform (30 mL) and triethylamine (5 mL) was
added dropwise at room temperature to a solution of the oily product 12 (0.8 g, 1.5 mmol) in
chloroform. After the addition was complete the mixture was stirred for 1h at room temperature.
Excess chloroform was distilled off under reduced pressure and the solid residue was suspended in
acetone (15 mL). The precipitate was filtered, the filtrate was concentrated under reduced pressure and
the remaining solid residue suspended in toluene (15 mL). After recrystallization from (1:1) DMF-
ethanol, orange-brown crystals were obtained in the yield of 0.58 g (56.70%), mp 224-227°C; IR

Molecules 2002, 7
880
(cm-1) (KBr): 1600 (C=C), 1662 (CONH), 3295 (NH), 3397 (NH); 1H-NMR (DMSO-d6) (d ppm): 6.87
(1H, s, Hg), 7.13-7.19 (4H, m, Harom.), 7.22 (1H, d, J = 3.67 Hz, He), 7.26 (1H, ABsyst., J = 3.97 Hz, J =
4.57 Hz, H ), 7.36 (1H, d, J = 3.97 Hz, Hf), 7.65 (1H, d, J = 3.97 Hz, Hc), 7.82 (1H, s, H ), 7.84 (1H,
b
d
d, J = 5.19 Hz, H ); 13C-NMR (DMSO-d6) (d ppm): 115.2, 115.5, 122.2, 122.5, 122.6, 126.3, 129.9,
a
131.8, 134.5, 137.7, 145.6, 157.0, 160.2, 165.6; Anal. Calcd. for: C36H24O2F2N2S4: C, 63.32; H, 3.52;
N, 4.10; S, 18.80%; Found: C, 63.55; H, 3.96, N, 3.89; S, 18.92%.
(Z)- and (E)-3-(2-furyl)-2-(2-thienyl)acrylic acids (14) and (15).
Compounds 14 and 15 were prepared in a manner described earlier [23, 27] from
2-furancarboxaldehyde (7.54 g, 0.078 mol) and thiophene-2-acetic acid (10 g, 0.07 mol) in acetic
anhydride (10 mL) and triethylamine (10 mL). After recrystallization from methanol, 8.3 g (53.90%)
of the (Z)- isomer, mp 197-200°C and 1.9 g (12.60%) of the (E)-isomer, mp 178-184°C were
1
obtained; IR (cm-1) (KBr) for (15): 1615 (C=C), 1670 (COOH); H-NMR (DMSO-d6) (d ppm): 6.22
(1H, d, J = 3.36 Hz, H), 6.53 (1H, ABsyst., J = 3.67 Hz, J = 4.88 Hz, Hb), 7.03 (1H, d, J = 3.60 Hz,
c
He), 7.12 (1H, ABsyst., J = 3.66 Hz, J = 4.89 Hz, H ), 7.65 (1H, d, J = 4.58 Hz, Hg), 7.67 (1H, s, H ),
f
d
7.75 (1H, d, H), 12.6 (1H, s, COOH); Anal. Calcd. for: C11H8O3S: C, 59.99; H, 3.66; S, 14.56%;
a
Found: C, 59.87; H, 3.61; S, 14.62%.
Ethyl (E)-3-(2-furyl)-2-(2-thienyl)acrylate (16).
Ethyl ester 16 was prepared in the manner described for the preparation of 3 by refluxing acid 15
(14.0 g, 0.064 mol) dissolved in absolute ethanol (250 mL) containing conc. sulphuric acid (2 mL) for
17h. The crude product was recrystallized from ethanol. The yield was 10.8 g, (68.80%), mp 58-59°C;
1
IR (cm-1) (KBr): 1615 (C=C), 1700 (COOEt); H-NMR (DMSO-d6) (d ppm): 1.20 (3 H, t, J = 7.32 Hz,
J = 7.02 Hz, CH3), 4.20 (2H, q, J = 7.02 Hz, CH ), 6.25 (1H, d, J = 3.67 Hz, Hc), 6.54 (1H, ABsyst., J =
2
3.67 Hz, J = 4.88 Hz, H), 7.05 (1H, d, J = 3.60 Hz, He), 7.14 (1H, ABsyst., J = 3.67 Hz, J = 4.88 Hz,
b
Hf), 7.67 (1H, d, J = 4.57 Hz, Hg), 7.69 (1H, s, H ), 7.78 (1H, d, Ha); Anal. Calcd. for: C13H12O3S: C,
d
62.89; H, 4.87; S, 12.91%; Found: C, 62.93; H, 4.83; S, 13.02%.
Ethyl (Z)-3-[5-formyl-(2-furyl)]-2-[5-formyl-(2-thienyl)]acrylate (17)
Compound 17 was prepared in a manner similar to the preparation of 4, but starting from 16 (11.00
g, 0.044 mol) dissolved in DMF (21 mL) to which POCl (22 mL, 0.240 mol) was added dropwise
3
under stirring and cooling at a temperature not exceeding 10°C. The gummy product was recrystallized
from (1:2) benzene-hexane to give a yellow crystalline product (5.2 g, 38.60% yield), mp 134-136°C;
1
IR (cm-1) (KBr): 1665 (CHO), 1675 (CHO), 1710 (COOEt); H-NMR (CDCl ) (d ppm): 1.27 (3H, t, J
3
= 7.1 Hz, CH3), 4.31 (2H, q, J = 7.05 Hz, CH2), 6.30 (1H, d, J = 3.65 Hz, Hb), 7.14 (1H, d, J = 3.93
Hz, H), 7.20 (1H, d, J = 3.65 Hz, H ), 7.80 (1H, d, J = 3.94 Hz, H), 7.84 (1H, s, H ), 9.59 (1H, s,
d
a
e
c

Molecules 2002, 7
881
13
CHO), 9.97 (1H, s, CHO); C-NMR (CDCl3) (d ppm): 14.0, 62.1, 127.0, 144.1, 145.4, 152.7, 153.7,
164.8, 177.7, 182.7; Anal. Calcd. for C H12O5: C, 59.21; H, 3.95; S, 10.53%. Found: C, 59.43; H,
15
3.95; S, 10.20%.
Ethyl (Z)-3-[5-(2-carboxy)ethenyl-(2-furyl)]-2-[5-(2-carboxyethenyl)-(2-thienyl)]acrylate (18)
Dialdehyde 17 (3.00g, 0.01 mol) was condensed with malonic acid (2.25g, 0.02 mol) in pyridine
(55 mL) to which a few drops of piperidine were added. The reaction mixture was heated for 1h at 30-
40°C and for 2 h at 100°C. After cooling, ice was added (300 g) and the reaction mixture was acidified
with 20% hydrochloric acid. Crude product was recrystallized from (2:1) ethanol-dioxane to give 1.6 g
(41.70%) of orange crystals, mp 240-244°C; IR (cm-1) (KBr): 1605 (C=C), 1625 (C=C), 1670
1
(COOH), 1690 (COOH), 1710 (COOEt); H-NMR (DMSO-d6) (d ppm): 1.23 (3H, t, J = 7.06 Hz,
CH3), 4.31 (2H, q, J = 7.05 Hz, CH ), 5.79 (1H, d, J = 15.87 Hz, Hethylenic), 6.18 (1H, d, J = 15.81 Hz,
2
Hethylenic), 6.91 (1H, d, J = 3.49 Hz, Ha), 6.96 (1H, d, J = 3.43 Hz, H ), 7.14 (1H, d, J = 3.67 Hz, H ),
b
d
7.51 (1H, d, J = 3.66 Hz, He), 7.25 (1H, d, J = 15.81 Hz, Hethylenic), 7.68 (1H, s, Hc), 7.75 (1H, d, J =
15.81 Hz, Hetylenic), 12.47 (1H, s, COOH); 13C-NMR (DMSO) (d ppm): 14.1, 61.5, 117.6, 117.9, 118.9,
121.0, 122.1, 128.2, 129.8, 130.1, 131.4, 136.6, 138.8, 140.6, 151.3, 152.9, 165.7, 167.1, 167.5; Anal.
Calcd. for C19H16O7S: C, 58.76; H, 4.12; S, 8.25%; Found: C, 58.54; H, 4.41; S, 8.43%.
3-Chloro-5-{2-ethoxycarbonyl-2-[3'-chloro-2'-chlorocarbonyl-5'-thieno[3,2-b]thienyl]ethenyl}
thieno[3,2-b]furan-carbonylchloride (19)
Compound 19 was prepared in a manner similar to the preparation of 7, starting from 18 (1.00 g,
2.6 mmol) and SOCl2 (14 mL, 0.193 mol), by stirring for 15 min under external cooling on ice. More
SOCl2 (1 mL) and a few drops of pyridine were then added dropwise. The reaction mixture was stirred
for 0.5 h at room temperature and for 40 h at 80°C. Excess SOCl was removed under reduced
2
pressure and the remaining material was extracted with hot hexane. After the removal of the solvent an
oily product (0.50 g, 35.0%) was obtained which was used without further purification in the next step.
6-Chloro-2-{2-[3-chloro-2-(p-fluorophenylcarbamoyl)-5-thieno[3,2-b]thienyl]-2-{ethoxycarbonyl
-ethenyl}thieno[3,2-b]furan-5-carbox-p-fluoroanilide (20)
Compound 20 was prepared from 19 (0.5 g, 0.001 mol) in chloroform (5 mL) and p-fluoroaniline
(0.25 g, 0.002 mol) dissolved in chloroform (5 mL) in a manner similar to the preparation of 8. The
crude product was recrystallized from DMF. Compound 20, mp 249-251°C was obtained in 0.38 g
-1
(50.60%) yield; IR (cm ) (KBr): 1615 (C=C), 1673 (CONH), 1720 (COOEt), 3380, 3410 (NH);
1H-NMR (DMSO-d6) (d ppm): 1.33 (3H, t, J = 7.13 Hz, CH3), 4.46 (2H, q, J = 7.09 Hz, CH ), 7.22
2
(1H, s, Ha), 7.15-7.28 (4H, m, Harom), 7.68 (1H, s, Hc), 7.64-7.78 (4H, m, Harom.), 8.20 (1H, s, Hethylenic),
13
10.3 (2H, s, NH); C-NMR (DMSO-d6) (d ppm): 14.1, 61.9, 115.4, 115.7, 117.6, 119.1, 122.3, 123.1,

Molecules 2002, 7
882
123.2, 123.3, 123.4, 126.8, 126.9, 127.5, 134.9, 136.4, 136.7, 144.0, 150.4, 151.8, 157.5, 160.7, 161.0,
166.9; Anal. Calcd. for C H18F2Cl2N2O5S3: C, 52.91; H, 2.56; N, 3.98; S, 13.68%; Found: C, 53.57;
31
H, 2.92; N, 4.25; S, 13.45%.
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28. CCDC 199584 contains the supplementary crystallographic data for this paper. These data can be
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Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk).
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Sample Availability: Samples of compounds 5 and 13 are available from authors.
© 2002 by MDPI (http://www.mdpi.org). Reproduction is permitted for noncommercial purposes.