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doi.org/10.1002/cplu.202100062
ChemPlusChem
analyses show that the furan cores favour the formation of
strong π-stacking that quenches the solid state emission.
Finally, the lengthening of the extended systems with the
presence of two cyanovinyl bonds, induces the formation of a
111.0, 110.8, 105.5, 98.9, 64.1, 56.1. HRMS (TOF) calculated for
C H NO : 305.1052, found: 305.10464.
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19 15
3
(
E)-2-(benzofuran-2-yl)-3-(3,4,5-trimethoxyphenyl)
2
D π-stacking favourable to the development of organic field
acrylonitrile: Be3
effect transistors.
1
Yellow solid (70% yield). . H NMR (CDCl ):, 7.73 (s,1H), 7.61 (d, 1H,
3
J=7.1 Hz), 7.49 (d, 1H, 7.7 Hz), 7.37–7.27 (m, 2H), 7.24 (s,2H), 7.04 (s,
1
3
1
H), 3.95 and 3.94 (2 s, 9H). C NMR (CDCl ): 155.3, 153.4, 151.3,
3
Experimental Section
Detailed protocols for the synthesis of 2-coumaranone, ylide Y and
aldehydes DFF and FuCN are presented in the Supporting
Information.
140.8, 140.1, 128.5, 125.7, 123.6, 121.6, 116.5, 111.1, 111.0, 106.9,
1
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06.2, 100.5, 61.1, 56.2. HRMS (TOF) calculated for C H NO :
35.11521, found: 335.11495.
20 17 4
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(E)-5-(2-(benzofuran-2-yl)-2-cyanovinyl)cyanofuran: Fu1
H NMR and C NMR spectra were obtained at 300 and 75 MHz
1
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respectively with CDCl3 as solvent and the H and C chemical
shifts were determined by reference to residual non deuterated
solvent resonances. Data are reported as follows: chemical shift in
ppm (δ), multiplicity (s=singlet, d=doublet, t=triplet, m=
multiplet), integration and coupling constant (Hz).
1
Orange solid (70% yield). H NMR (CDCl ):, 7.63 (d, 1H, J=7.8 Hz),
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7.58 (s,1H), 7.49 (d, 1H, 8.2 Hz), 7.41 (t, 1H, J=7.2 Hz) 7.31 – 7.24 (m,
13
3
1
H), 7.16 (s, 1H). C NMR (CDCl ): 155.7, 153.5, 149.8, 128.3, 127.3,
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26.9, 124.0 (2), 123.6, 122.1, 114.8, 111.3, 110.9, 109.2, 103.2. HRMS
(
TOF) calculated for C H N O : 260.05913, found: 260.05856.
16 8 2 2
Synthesis of 2-(benzofuran-2-yl)acetonitrile (1)
(2E,2’E)-3,3’-(furan-2,5-diyl)bis(2-(benzofuran-2-yl)
acrylonitrile): Fu2
To a solution of 2-coumaranone (500 mg, 3.73 mmol) in toluene
(5 mL) was added ylide Y (1.13 g, 3.75 mmol). The mixture was
irradiated in a CEM Discover microwave (300 W, 150°C, 5 bars) for
1
Red solid (75% yield). H NMR (CDCl ): 7.64 (s,1H), 7.60 (d, 1H, J=
3
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.7 Hz), 7.50 (d, 1H, 8.2 Hz), 7.39 (s, 1H), 7.40–7.25 (m, 2H), 7.11 (s,
15 min. The solvent was then evaporated and the residue was
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1H). C NMR (CDCl
21.8, 118.5, 115.6, 111.2, 107.9, 100.5. HRMS (TOF) calculated for
C H N O : 402.09989, found: 402.10008.
): 155.6, 151.9, 150.7, 128.5, 126.4, 124.2, 123.8,
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treated with 10 mL of methanol. The solid corresponding to
insoluble part of oxide of triphenylphosphine was filtered and
washed with 5 mL of methanol (830 mg, 2.98 mmol). The filtrate
containing the target molecule 1 was evaporated and the residue
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was purified over silica gel (petroleum ether/ methylene chloride
Cycloaddition [2+2] (1R,2R,3S,4S)-1,3-di(benzofuran-2-yl)-2,
4-bis(4-methoxyphenyl)cyclobutane-1,3-dicarbonitrile: Cy-Be1
1
2
/8) to give a white solid (450 mg, 2.87 mmol, 77% yield). H NMR
(
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CDCl ): 7.56 (dd, 1H, J=7.3 Hz, J=1.1 Hz), 7.46 (d, 1H, J=7.9 Hz),
3
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.35-7.21 (m, 2H), 6.75 (d, 1H, J=1.1 Hz), 3.92 (d, 2H, J=1.1 Hz).
C
Ground powder of Be1 (15 mg) was irradiated for 18–24 h with a
366 nm lamp (P=10 W). The cycloaddition can be followed by TLC
with eluent DCM/EP (1/1) with Rf=0.8 for Be1 and Rf=0.2 for Cy-
Be1. The resulting solid was dissolved in 1 mL of dichloromethane
and chromatographed under silica gel (eluent DCM/EP 1/1) to
separate Be1 and Cy-Be1.
NMR (CDCl ): 155.4, 146.1, 127.9, 125.0, 123.4, 121.2, 115.1, 111.3,
3
105.6, 18.2. HRMS (EI) calculated for C H NO: 157.0528, found:
10
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157.0525.
General Knoevenagel condensations procedure
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White solid (70% yield). H NMR (CDCl ): 7.56–7.48 (m, 4H), 7.38-
3
A mixture of aldehyde (2 mmol), carbonitrile derivative 1 (2 mmol
or 4 mmol) and catalytic amount of NaOtBu (10% mol) was stirred
in ethanol (5 or 10 mL) for 12 h at room temperature. The resulting
precipitate was filtered then washed with cold ethanol. Afterwards,
the solid was dried in high vacuo to afford crystalline powders.
7.24 (m, 8H), 6.90 (s, 2H), 6–78 (d, 4H, J=8 Hz), 5,35 (s, 2H), 3.73 (s,
1
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6H). C NMR (CDCl ): 160.1, 155.3, 149.3, 130.2,127.5,125.5,124.1,
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123.6, 121.6, 118.9, 114.2, 111.7, 108.2, 55.3, 54.8, 45.3. HRMS (TOF)
calculated for C H N O Na: 573.17848, found: 573.17992
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X-ray crystallography
(E)-2-(benzofuran-2-yl)-3-(4-methoxyphenyl)acrylonitrile: Be1
Single crystals suitable for X-ray diffraction analyses were obtained
for all the compounds by the slow evaporation of ethanol –
chloroform solution.
1
Pale yellow solid (65% yield). H NMR (CDCl ): 7.93 (d, 2H, J=
3
8.7 Hz), 7.75 (s,1H), 7.58 (d, 1H, 7.7 Hz), 7.48 (d, 1H, 7.7 Hz), 7.32–
1
3
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.23 (m, 2H), 7.00 (d, 2H, 8.7 Hz), 6.98 (s,1H), 3.89 (s, 3H). C NMR
X-ray single-crystal diffraction data were collected on an a Rigaku
Oxford Diffraction SuperNova diffractometer equipped with Atlas
CCD detector and mirror monochromated micro-focus Cu-Kα
radiation (λ=1.54184 Å). The structures were solved by direct
methods or dual-space algorithm (using ShelxS/ShelXT) and refined
(
1
CDCl ): 162.0, 155.2, 151.8, 140.0, 131.6, 128.8, 126.2, 125.5, 123.6,
21.6, 116.8, 114.7, 111.1, 105.6, 99.0, 55.6. HRMS (TOF) calculated
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for C H NO : 275.09408, found: 275.09403.
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on F by full matrix least-squares techniques using SHELX (G.M.
(E)-2-(benzofuran-2-yl)-3-(3,4-dimethoxyphenyl)acrylonitrile:
Sheldrick, 1997, 2014, 2016, 2018) package. All non-hydrogen atoms
were refined anisotropically and the H atoms were included in the
calculation without refinement. Multiscan empirical absorption was
corrected using CrysAlisPro program (CrysAlisPro, Agilent Technolo-
gies,/Rigaku Oxford Diffraction, 2014–2019).
Be2
1
Pale yellow solid (75% yield). H NMR (CDCl ):, 7.75 (s,1H), 7.72 (d,
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1H, J=2.2 Hz), 7.59 (d, 1H, 7.0 Hz), 7.48 (d, 1H, 7.6 Hz), 7.43 (dd, 1H,
J=8.4 Hz, J=2.2 Hz), 7.36–7.23 (m, 2H), 7.00 (s,1H), 6.95 (d, 1H, J=
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.4 Hz), 3.99 and 3.96 (2 s, 6H). C NMR (CDCl ): 155.2, 151.7, 151.6,
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149.2, 140.1, 128.6, 126.3, 125.5, 124.9, 123.5, 121.5, 116.8, 111.1,
ChemPlusChem 2021, 86, 475–482
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