Design and synthesis of new functionalized isoindigo and (3Z,3′Z)-3,3′-(ethane-1,2-diylidene)bis(indolin-2-one) derivatives

Article abstract of DOI:10.1007/s00706-018-2272-1

Abstract: A library of N,N-substituted isoindigo derivatives were prepared by reaction of isoindigo with a variety of alkylating agents in the presence of MeONa under mild conditions in yields of 65–80%. A new, more efficient synthesis of (3Z,3′Z)-3,3′-(ethane-1,2-diylidene)bis(indolin-2-one) is described by reaction of oxindole with glyoxal at reflux in methanol—a small library of N,N′-substituted derivatives were also prepared in 60–70% yield. Graphical abstract: [Figure not available: see fulltext.].

Full text of DOI:10.1007/s00706-018-2272-1

Monatshefte für Chemie - Chemical Monthly
https://doi.org/10.1007/s00706-018-2272-1(0123456789(). -, vo Vl
)
0
1
2
3
4
5
6
7
8
9
(
)
.
-
v
o
l
V
)
ORIGINAL PAPER
Design and synthesis of new functionalized isoindigo and (3Z,30Z)-3,30-
(ethane-1,2-diylidene)bis(indolin-2-one) derivatives
Gholamhossein Khalili1,2 Anthony C. Willis3 Paul A. Keller1
•
•
Received: 5 May 2018 / Accepted: 1 July 2018
Ó Springer-Verlag GmbH Austria, part of Springer Nature 2018
Abstract
A library of N,N-substituted isoindigo derivatives were prepared by reaction of isoindigo with a variety of alkylating agents
in the presence of MeONa under mild conditions in yields of 65–80%. A new, more efficient synthesis of (3Z,30Z)-3,30-
(ethane-1,2-diylidene)bis(indolin-2-one) is described by reaction of oxindole with glyoxal at reflux in methanol—a small
library of N,N0-substituted derivatives were also prepared in 60–70% yield.
Graphical abstract
R
N
H
N
O
O
DMF
MeONa,
+
RBr
45 6 h
O
°C,
O
N
N
R
H
R=
Br.
groups
alkene,
alkyl, allyl, cyclohexyl,
18
+
SO functional
2
examples
65-80 %
Cl, CN, O, S,
R
H
N
N
O
N
O
O
reflux
H
MeOH,
6 h
O
+
H
DMF
2
MeONa,
45 8 h
RBr
N
H
°C,
O
O
O
N
H
R
3
examples
60-70%
Keywords Isoindigo Á Oxindole Á (3Z,30Z)-3,30-(Ethane-1,2-diylidene)bis(indolin-2-one)
Introduction
optical and electronic materials [1, 2]. In this area, organic
semiconductors are finding widespread use as replacements
for their inorganic counterparts to develop their potential
applications in flexible and low-cost organic opto-elec-
tronic devices, such as organic field-effect transistors
(OFETs) [3–5], organic photovoltaic (OPVs) [6–8], and
organic light-emitting devices (OLEDs) [9, 10]. A suc-
cessful method to prepare of p-conjugated organic mate-
rials entails the creation of donor–acceptor (D–A) units,
having both electron-donating and electron-withdrawing
structures [11]. In this approach, a p-electron rich donor is
combined with a p-electron-deficient acceptor, with the
interaction of their frontier orbitals, reducing the effective
bandgap [12]. Among them, perylene imides [13], bithio-
phene imides [14], naphthalenediimides [15], and dike-
topyrroles [11, 16] have been extensively studied as
polymeric donors and building blocks for donor–acceptor
type molecular architecture in recent years. One amide/
imide acceptor employed to date is isoindigo which has
attracted considerable attention as a useful building block
Organic p-conjugated compounds are increasingly impor-
tant as promising candidates in conductance, photonics,
and magnetism due to their p-electronic communication. In
particular, organic p-conjugated small molecules have been
studied extensively because of their unique applications in
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s00706-018-2272-1) contains
supplementary material, which is available to authorized
users.
& Gholamhossein Khalili
khalili_gh1352@yahoo.com
1
School of Chemistry, University of Wollongong,
Wollongong, NSW 2522, Australia
2
Chemistry Department, Bushehr Branch, Islamic Azad
University, PO Box 7519619555, Bushehr, Iran
3
Research School of Chemistry, Australian National
University, Canberra, ACT 2601, Australia
123

G. Khalili et al.
to construct high-performance organic semiconductors
[17–19]. The two fused, planar lactam rings adjacent to the
aryl moieties endow the unit with a strong electron-with-
drawing nature and represent a highly reactive conjugated
system. This allows these molecules to be incorporated into
materials for transistor applications due to their extended
delocalised planar aromatic p-system, which may facilitate
p–p stacking and enable high-charge carrier mobility [20].
Copolymers based on these nitrogen-containing electron-
deficient dyes have been developed for organic solar cells
[21].
showed a resonance at 55.9 ppm assigned to the CH2S
group.
The utility of the protocol was extended to the reaction
of 2e with 2-mercaptobenzothiazole (5) in CH2Cl2 at reflux
to give the (E)-1,10-bis[5-(benzo[d]thiazol-2-ylthio)-
pentyl]-[3,30-biindolinylidene]-2,20-dione (6a) in satisfac-
tory yield (Scheme 3). Analysis of the FT-IR spectrum of
6a showed absorption at 1690 cm-1 assigned to the car-
bonyl moiety.
Molecules that contain a pyrimidine nucleus possess a
wide range of biological activities and occur in living
systems in the form of vitamins and nucleic acids [26–28]
and, therefore, compound 8a (Scheme 4) was synthesised
by reaction of 2e with 2-mercaptopyrimidine (7) in the
presence of trimethylamine at 80 °C for 4 h. Analysis of
the 1H NMR spectrum revealed a triplet at 6.93 ppm
(J = 8.0 Hz) and a doublet at 8.47 ppm (J = 8.0 Hz),
assigned to the pyrimidyl H50 and H40/60 protons, respec-
tively, whereas the 13C NMR spectrum displayed the
characteristic resonance at 166.8 ppm assigned to the iso-
indigo carbonyl, and a resonance at 156.1 ppm assigned to
the pyrimidyl C20. The HR-ESI mass spectrum showed a
peak at m/z = 617.1768, assigned to the molecular formula
C32H30N6O2S2 and was indicative of the addition of two
thiopyrimidine unit.
Results and discussion
In general, N-alkyl isoindigo compounds are prepared by
the reaction of alkyl halides with isoindigo in the presence
of potassium carbonate under thermal conditions (100 °C)
[22]. In addition, the reaction of haloalkyl isatins with
tris(diethylamino)phosphine at low temperature (- 60 °C)
forms isoindigo compounds with two haloalkyl functional
groups [23–25]. Due to the widespread applications of
substituted isoindigos, we investigated the breadth of N,N0-
disubstituted analogs, with subsequent reactions to extend
the catalog of possible derivatives—this included an array
of chains or rings bearing bromo, chloro, nitrile, benzyl
ether, allyl, alkene, cyclohexene, and cyclohexane. Further,
we applied this strategy to the reaction with the p-extended
conjugated compound, (3Z,30Z)-3,30-(ethane-1,2-diyli-
dene)bis(indolin-2-one).
Sulfones can also possess interesting biological activity
[29, 30] and, therefore, (E)-1,10-bis(5-bromopentyl)-[3,30-
biindolinylidene]-2,20-dione (2e) was reacted with sodium
benzenesulfinate producing (E)-1,10-bis[5-(phenylsul-
fonyl)pentyl]-[3,30-biindolinylidene]-2,20-dione
(10a),
Therefore, to a stirred solution of isoindigo 1 sodium
methoxide was added followed by the alkyl bromide, and
after stirring at 45 °C for 6 h, and upon workup, the N,N0-
disubstituted isoindigos were isolated in 65–80% yield
(Scheme 1).
incorporating the sulfonyl functional group (Scheme 5).
The isoindigo analog (3Z,30Z)-3,30-(ethane-1,2-diyli-
dene)bis(indolin-2-one) (12) is an extended p-conjugate
dimeric heterocycle in which two oxindole rings are con-
nected by an ethylene. This structure is less rigid than
isoindigo due rotational freedom in the single bonds. Its
synthesis is reported as a two-step process (22 and 74%
yield, 16% overall) [31] and its application as an attractive
building block for conjugated photovoltaic polymers has
been recently reported [32]. Therefore, we extended our
isoindigo alkylation strategy to include the p-extended
heterocycles 12. The synthesis of the parent structure was
achieved by heating oxindole 11 with glyoxal in methanol
at reflux producing 12 in 32% yield in a single step
(Scheme 6).
In a typical example, analysis of the 13C NMR spectra of
compound 2m showed a resonance at d = 166.9 ppm
assigned to the carbonyl group, confirming the molecular
1
symmetry. Analysis of the H NMR spectrum showed a
doublet at 9.16 ppm with J = 8.0 Hz assigned to H4. For
this compound, broad absorption bands with two maxima
at 280 and 390 nm were observed in the UV–Vis spectrum.
The structure of 2m was unambiguously confirmed by
X-ray crystallographic analysis (Fig. 1).
The substrate scope of substituted isoindigos was then
further explored through the reaction of (E)-1,10-bis(5-
bromopentyl)-[3,30-biindolinylidene]-2,20-dione (2e) with
thios. The reaction of 2e with sodium thiophenolate (3) in
DMF at 70 °C for 6 h gave (E)-1,10-bis[5-(phenylthio)-
pentyl]-[3,30-biindolinylidene]-2,20-dione (4a) in 65%
yield (Scheme 2). Analysis of the 1H NMR spectrum
showed resonances at 7.45, 7.52, and 7.78 ppm assigned to
the thiophenyl protons, whereas the 13C NMR spectrum
Utilizing the same alkylation strategy, (3Z,30Z)-3,30-
(ethane-1,2-diylidene)bis(indolin-2-one)
4 was reacted
with a variety of alkyl halides to produce 13a–13c in yields
of 60–70% (Scheme 7). Analysis of the 1H NMR spectra of
(3Z,30Z)-3,30-(ethane-1,2-diylidene)bis(1-isopropylindolin-
2-one) (5a) showed a sharp singlet at 8.98 ppm, assigned to
the two central olefinic protons in an s-trans configuration.
Analysis of the FT-IR spectrum of 13a showed absorption
123

Design and synthesis of new functionalized isoindigo and (3Z,30Z)-3,30-(ethane-1,2-diylidene)…
Scheme 1
at 1689 cm-1 assigned to the two carbonyl moieties and
Conclusion
analysis of the UV–Vis spectrum showed two maximum
absorptions at 228 and 386 nm for this red compound.
In summary, we have developed an efficient, high yielding,
and attractive alkylation of isoindigo and its p-extended
analog 12 with a range of alkylating agents using MeONa
123

G. Khalili et al.
as the base under mild conditions. Previous alkylation
strategies for isoindigo relied on DMF solutions using
K2CO3 and heating to 100 °C for up to 24 h—while these
could produce reasonable yields [18], our milder conditions
with shorter reaction represents an improved strategy. The
products are highly functionalized molecules, potentially
amenable to further manipulations. Notably, the prepara-
tion of analog (3Z,30Z)-3,30-(ethane-1,2-diylidene)bis(in-
dolin-2-one) (12) in 32% yield as a p-extended conjugated
compound by condensation of oxindole with glyoxal
compound represents a more efficient single step, higher
yielding methodology using inexpensive reagents com-
pared to that previously published. We are currently using
this new method for the construction of new isoindigo
derivatives with potential electronic, biological, and phar-
maceutical activities.
Experimental
Reagents and solvents were purchased reagent grade and
used without further purification except isoindigo [33]. All
reactions were performed in standard oven-dried glassware
Fig. 1 The X-ray crystal structure 2m
Scheme 2
Scheme 3
123

Design and synthesis of new functionalized isoindigo and (3Z,30Z)-3,30-(ethane-1,2-diylidene)…
Scheme 4
Scheme 5
(IR) spectra were recorded on neat samples. UV–Vis
Scheme 6
spectra were recorded with solutions of samples in CH2Cl2.
Thin-layer chromatography (TLC) was performed using
Silica Gel F254 aluminum sheets. Column chromatography
was performed under gravity using Silica Gel 60
(0.063–0.200 mm). Eluents are in volume to volume
(v:v) proportions. Solvent extracts or chromatographic
fractions were concentrated by rotary evaporation in vacuo.
General procedure for the preparation of 2
1
under a nitrogen atmosphere unless otherwise stated. H
and 13C NMR spectra (CDCl3 solutions) were recorded at
400 and 100.6 MHz with chemical shifts (d) reported in
parts per million relative to TMS (d = 0 ppm) or CDCl3
(d = 77.0 ppm) as internal standards. Coupling constants
(J) are reported in Hertz (Hz). Multiplicities are reported as
singlet (s), broad singlet (bs), doublet of doublets (dd), or
multiplet (m). High-resolution electrospray (HR-ESI—
single quadrupole) mass spectra have their ion mass to
charge (m/z) values stated with their relative abundances as
a percentage in parentheses. Peaks assigned to the molec-
ular ion are denoted by [M?H]? or [M?Na]?. Infrared
To a magnetically stirred solution of 131 mg isoindigo 1
(0.5 mmol) in 3 cm3 DMF, 59.4 mg sodium methoxide
solution (1.1 mmol) was added in 2 cm3 DMF at room
temperature. The reaction mixture stirred for 30 min, fol-
lowed by the addition of the alkyl bromide (3 mmol) and
the reaction stirred for 6 h at 45 °C. The mixture was
poured into 10 cm3 H2O, extracted with 20 cm3 CH2Cl2,
dried (MgSO4), and the solvent was removed under
reduced pressure. The residue was subjected to silica gel
column chromatography using hexane–ethyl acetate as
eluent.
123

G. Khalili et al.
Scheme 7
(E)-1,10-Diallyl-[3,30-biindolinylidene]-2,20-dione (2a) Dark
red powder; yield 80%; m.p.: 166 °C. Spectroscopic data
are in agreement with that reported [25].
(400.1 MHz, CDCl3): (Z) d = 1.84–1.86 (m, 6H), 4.45 (dd,
J = 6.4, 0.4 Hz, 4H), 5.41–5.52 (m, 2H), 5.71–5.76 (m,
2H), 6.73–6.79 (m, 2H), 7.04 (td, J = 7.9, 1.1 Hz, 2H),
7.32 (td, J = 7.6,1.1 Hz, 2H), 9.20 (dd, J = 8.0, 0.4 Hz,
2H) ppm; 13C NMR (100.6 MHz, CDCl3): d = 13.2, 36.9,
108.1, 121.6, 123.9, 124.1, 128.4, 129.8, 132.2, 133.4,
144.6, 167.5 ppm; HRMS (ESI): [M?H]? calcd for
C24H23N2O2 371.1760, found 371.1774.
(E)-1,10-Dibut-3-en-1-yl-[3,30-biindolinylidene]-2,20-dione
(2b, C24H22N2O2) Dark red powder; yield 78%; m.p.:
-1
ꢀ
98 °C; IR (KBr): m = 1683, 1606, 1080, 669, 557 cm
;
1
kmax/nm (e) = 258 (4000), 374 (3850) nm (M-1 cm-1); H
NMR (400.1 MHz, CDCl3): d = 2.46 (td, J = 10.2, 1.1 Hz,
4H), 3.82–3.86 (m, 4H), 5.04–5.13 (m, 4H), 5.79–5.89 (m,
2H), 6.79 (dd, J = 7.8, 0.4 Hz, 2H), 7.04 (td, J = 7.7
1.0 Hz, 2H), 7.35 (td, J = 7.7, 1.2 Hz, 2H), 9.18 (dd,
J = 8.0, 0.7 Hz, 2H) ppm; 13C NMR (100.6 MHz, CDCl3):
d = 31.8, 39.4, 107.8, 117.5, 121.7, 122.2, 129.9, 132.3,
133.4, 134.4, 144.4, 167.8 ppm; HRMS (ESI): [M?H]?
calcd for C24H23N2O2 371.1760, found 371.1754.
(E)-1,10-Dicyclohex-2-en-1-yl-[3,30-biindolinylidene]-2,20-
dione (2d, C28H26N2O2) Dark red powder; yield 68%; m.p.:
ꢀ
181 °C; IR (KBr): m = 1689, 1603, 1465, 1108, 725,
681 cm-1; kmax/nm (e) = 238 (4000), 403 (3940) nm
(M-1 cm-1); 1H NMR (400.1 MHz, CDCl3): d = 1.78–1.85
(m, 2H), 1.92–1.98 (m, 6H), 2.01–2.18 (m, 4H), 5.25–5.27
(m, 2H), 5.67 (d, J = 10.1 Hz, 2H), 6.00–6.03 (m, 2H),
6.98–7.05 (m, 4H), 7.24–7.28 (m, 2H), 9.13 (dd, J = 7.9,
0.7 Hz, 2H) ppm; 13C NMR (100.6 MHz, CDCl3): d = 21.8,
24.5, 25.8, 48.5, 110.3, 121.8, 121.9, 127.6, 129.7, 131.0,
132.0, 133.4, 134.8, 167.6 ppm; HRMS (ESI): [M?Na]?
calcd for C28H26N2O2Na 445.1892, found 445.1904.
(E)-1,10-(E/Z)-Dibut-2-en-1-yl-[3,30-biindolinylidene]-2,20-dione
(2c, C24H22N2O2) Dark red powder; yield 76%; m.p.:
ꢀ
128 °C; IR (KBr): m = 1683, 1606, 1433, 1378, 1103,
776 cm-1; kmax/nm (e) = 263 (4000), 363 (3791) nm
(M-1 cm-1);
1H
NMR
(400.1 MHz,
CDCl3):
(E) d = 1.67–1.69 (m, 6H), 4.33–4.35 (m, 4H), 5.41–5.52
(m, 2H), 5.71–5.76 (m, 2H), 6.73–6.79 (m, 2H), 7.04 (td,
J = 7.9, 1.1 Hz, 2H), 7.32 (td, J = 7.6, 1.1 Hz, 2H), 9.20
(dd, J = 8.0, 0.4 Hz, 2H) ppm; 13C NMR (100.6 MHz,
CDCl3): d = 17.6, 41.6, 108.3, 122.2, 123.9, 129.1, 129.9,
130.0, 132.2, 133.4, 144.6, 167.5 ppm; 1H NMR
(E)-1,10-Bis(5-bromopentyl)-[3,30-biindolinylidene]-2,20-
dione (2e) Dark red powder; yield 76%; m.p.: 138 °C.
Spectroscopic data are in agreement with that reported
[23].
(E)-1,10-Bis(cyclohexylmethyl)-[3,30-biindolinylidene]-2,20-
dione (2f, C30H34N2O2) Dark red powder; yield 76%; m.p.:
123

Design and synthesis of new functionalized isoindigo and (3Z,30Z)-3,30-(ethane-1,2-diylidene)…
145 °C; IR (KBr): mꢀ = 1687, 1607, 1460, 1448, 1355,
1087, 773 cm-1; kmax/nm (e) = 276 (3952), 391 (3263) nm
(E)-1,10-Bis(3-bromopropyl)-[3,30-biindolinylidene]-2,20-
dione (2 k) Dark red powder; yield 77%; m.p.: 178 °C.
Spectroscopic data are in agreement with that reported
[23].
(M-1 cm-1);
1H
NMR
(400.1 MHz,
CDCl3):
d = 1.04–1.22 (m, 10H), 1.65–1.75 (m, 10H), 1.80–1.85
(m, 2H), 3.60 (d, J = 7.3 Hz, 4H), 6.77 (d, J = 7.6 Hz,
2H), 7.03 (td, J = 7.7, 1.0 Hz, 2H), 7.33 (td, J = 7.7,
1.1 Hz, 2H), 9.15 (dd, J = 8.0, 0.7 Hz, 2H) ppm; 13C NMR
(100.6 MHz, CDCl3): d = 25.7, 26.2, 31.1, 36.5, 46.4,
108.2, 121.6, 122.1, 129.8, 132.2, 133.5, 145.2, 168.2 ppm;
HRMS (ESI): [M?H]? calcd for C30H35N2O2 455.2699,
found 455.2691.
(E)-1,10-Bis[2-(benzyloxy)ethyl]-[3,30-biindolinylidene]-2,20-
dione (2 l, C34H30N2O4) Dark red powder; yield 86%;
ꢀ
m.p.: 130 °C; IR (KBr): m = 1683, 1604, 1465, 1347, 1031,
772, 696, 442 cm-1; kmax/nm (e) = 268 (4000), 394 (3089)
1
nm (M-1 cm-1); H NMR (400.1 MHz, CDCl3): d = 3.75
(t, J = 5.7 Hz, 4H), 4.00 (t, J = 5.7 Hz, 4H), 4.51 (s, 4H),
6.90 (d, J = 7.6 Hz, 2H), 7.03 (td, J = 7.7, 1.0 Hz, 2H),
7.21–7.27 (m, 10H), 7.29–7.31 (m, 2H), 9.15 (dd, J = 8.0,
0.7 Hz, 2H) ppm; 13C NMR (100.6 MHz, CDCl3):
d = 40.2, 67.4, 73.2, 108.6, 121.6, 122.2, 127.5, 127.6,
128.3, 129.7, 132.3, 133.3, 137.8, 144.9, 168.0 ppm;
HRMS (ESI): [M?Na]? calcd for C34H30N2O4Na
553.2103, found 553.2088.
(E)-1,10-Diisopentyl-[3,30-biindolinylidene]-2,20-dione (2 g,
C26H30N2O4) Dark red powder; yield 69%; m.p.: 106 °C;
IR (KBr): m = 1683, 1608, 1356, 1098, 764 cm-1; kmax/nm
ꢀ
1
(e) = 229 (1344), 277 (1505) nm (M-1 cm-1); H NMR
(400.1 MHz, CDCl3): d = 0.99 (d, J = 6.5 Hz, 12H),
1.55–1.61 (m, 4H), 1.64–1.74 (m, 2H), 3.78 (t, J = 5.8 Hz,,
4H), 6.77 (d, J = 7.4 Hz, 2H), 7.03 (td, J = 7.7, 1.0 Hz,
2H), 7.33 (td, J = 7.6, 1.1 Hz, 2H), 9.18 (dd, J = 8.0,
0.7 Hz, 2H) ppm; 13C NMR (100.6 MHz, CDCl3):
d = 22.5, 26.1, 36.0, 38.4, 107.7, 121.7, 122.1, 129.9,
132.2, 133.5, 144.6, 167.7 ppm; HRMS (ESI): [M?H]?
calcd for C26H31N2O4 403.2386, found 403.2388.
(E)-1,10-Bis(4-bromobutyl)-[3,30-biindolinylidene]-2,20-dione
(2m, C24H24Br2N2O2) Dark red powder; yield 71%; m.p.:
ꢀ
93 °C; IR (KBr): m = 1683, 1606, 1465, 1449, 1356, 773,
747 cm-1; kmax/nm (e) = 280 (3975), 390 (3706) nm
(M-1 cm-1);
1H
NMR
(400.1 MHz,
CDCl3):
d = 1.87–1.98 (m, 8H), 3.46 (t, J = 6.3 Hz, 4H), 3.83 (t,
J = 6.6 Hz, 4H), 6.81 (d, J = 7.7 Hz, 2H), 7.06 (td,
J = 7.8, 1.0 Hz, 2H), 7.37 (td, J = 7.7, 1.2 Hz, 2H), 9.16
(d, J = 8.0 Hz, 2H) ppm; 13C NMR (100.6 MHz, CDCl3):
d = 25.0, 28.7, 32.0, 37.9, 106.8, 120.6, 121.3, 128.9,
(E)-1,10-Diisobutyl-[3,30-biindolinylidene]-2,20-dione
(2 h,
C24H26N2O2) Dark red powder; yield 74%; m.p.: 138 °C;
ꢀ
IR (KBr): m = 1690, 1608, 1465, 1356, 1331, 1095, 775,
743 cm-1; kmax/nm (e) = 247 (4000), 361 (2626) nm
1
(M-1 cm-1); H NMR (400.1 MHz, CDCl3): d = 0.99 (d,
131.5, 132.4, 143.3, 166.9 ppm; HRMS (ESI): [M?Na]?
79
calcd for C24H Br2N2O2Na 553.0102, found 553.0115.
24
J = 6.6 Hz, 12H), 2.13–2.23 (m, 2H), 3.59 (d, J = 7.5 Hz,
4H), 6.78 (d, J = 7.8 Hz, 2H), 7.03 (td, J = 7.8, 1.0 Hz,
2H), 7.33 (td, J = 7.7, 1.1 Hz, 2H), 9.16 (dd, J = 8.0,
0.7 Hz, 2H) ppm; 13C NMR (100.6 MHz, CDCl3):
d = 20.3, 27.2, 47.5, 108.1, 121.6, 122.1, 129.8, 132.2,
133.5, 145.1, 168.2 ppm; HRMS (ESI): [M?H]? calcd for
C24H27N2O2 375.2090, found 375.2073.
(E)-6,60-(2,20-Dioxo-[3,30-biindolinylidene]-1,10-diyl)di-
hexanenitrile (2n, C28H28N4O2) Dark red powder; yield
ꢀ
78%; m.p.: 105 °C; IR (KBr): m = 1680, 1608, 1468, 1455,
1350, 1161, 1095, 759, 774, 671 cm-1; kmax/nm (e) = 267
(3960), 392 (2638) nm (M-1 cm-1); 1H NMR
(400.1 MHz, CDCl3): d = 1.52–1.58 (m, 4H), 1.67–1.77
(m, 8H), 2.34 (t, J = 7.1 Hz, 4H), 3.79 (t, J = 7.1 Hz, 4H),
6.77 (d, J = 7.4 Hz, 2H), 7.05 (td, J = 7.7, 1.0 Hz, 2H),
7.35 (td, J = 7.7, 1.1 Hz, 2H), 9.15 (dd, J = 8.0, 0.7 Hz,
2H) ppm; 13C NMR (100.6 MHz, CDCl3): d = 17.0, 25.0,
26.0, 26.7, 39.5, 107.7, 119.5, 121.6, 122.3, 129.9, 132.5,
133.4, 144.4, 167.8 ppm; HRMS (ESI): [M?Na]? calcd
for C28H28N4O2Na 475.2110, found 475.2105.
(E)-1,10-Bis(3-chloropropyl)-[3,30-biindolinylidene]-2,20-
dione (2i) Dark red powder; yield 76%; m.p.: 148 °C.
Spectroscopic data are in agreement with that reported
[24].
(E)-1,10-Dibenzhydryl-[3,30-biindolinylidene]-2,20-dione (2j,
C42H30N2O2) Dark red powder; yield 65%; m.p.: 293 °C;
ꢀ
IR (KBr): m = 1690, 1604, 1477, 1453, 1005, 762, 749,
663 cm-1; kmax/nm (e) = 274 (3736), 402 (2059) nm
(E)-1,10-Bis(5-phenylthio)-[3,30-biindolinylidene]-2,20-dione
(4a, C38H38N2O2S2) A mixture of 168 mg (E)-1,10-bis(5-
bromopentyl)-[3,30-biindolinylidene]-2,20-dione
1
(M-1 cm-1); H NMR (400.1 MHz, CDCl3): d = 6.40 (d,
J = 7.9 Hz, 2H), 6.95 (td, J = 8.0, 1.0 Hz, 2H), 7.04 (td,
J = 7.8, 1.2 Hz, 2H), 7.16 (s, 2H), 7.33 (br, 20H), 9.11 (dd,
J = 7.9, 0.8 Hz, 2H) ppm; 13C NMR (100.6 MHz, CDCl3):
d = 57.3, 110.5, 120.8, 121.0, 126.7, 127.4, 127.6, 128.6,
130.9, 132.3, 136.5, 143.0, 167.0 ppm; HRMS (ESI):
[M?H]? calcd for C42H31N2O2 595.2386, found 595.2403.
(2e,
0.3 mmol) and 132 mg sodium thiophenolate (3, 1 mmol)
in 5 cm3 DMF was stirred for 6 h at 70 °C. The resulting
mixture was extracted with CH2Cl2 (2 9 10 cm3), washed
with 10 cm3 water and the combined organic layers dried
(MgSO4) and concentrated. The residue was subjected to
flash column chromatography (silica gel) using petroleum
123

G. Khalili et al.
ether–ethyl acetate (4:1) as eluent to give the dione. Dark
ꢀ
(M-1 cm-1); 1H NMR (400.1 MHz, CDCl3): d = 1.88 (br,
8H), 3.20 (t, J = 6.6 Hz, 4H), 3.83 (t, J = 6.8 Hz, 4H), 6.79
(d, J = 7.6 Hz, 2H), 6.93 (t, J = 4.8 Hz, 2H), 7.02–7.06
(m, 2H), 7.32–7.36 (m, 2H), 8.47 (d, J = 4.8 Hz, 4H), 9.15
(d, J = 7.4 Hz, 2H) ppm; 13C NMR (100.6 MHz, CDCl3):
d = 25.6, 25.7, 29.3, 38.5, 106.8, 115.3, 120.6, 121.2,
128.9, 131.4, 132.4, 143.5, 156.1, 166.8, 171.3 ppm;
HRMS (ESI): [M?H]? calcd for C32H31N6O2S2 595.1950,
found 595.1946.
red powder; yield 65%; m.p.: 142 °C; IR (KBr): m = 1690,
1604, 1477, 1465, 1453, 1423, 1005, 745 cm-1; kmax/nm
1
(e) = 267 (3963), 395 (3883) nm (M-1 cm-1); H NMR
(400.1 MHz, CDCl3): d = 1.34–1.38 (m, 4H), 1.58–1.61
(m, 4H), 1.65–1.69 (m, 4H), 2.98 (t, J = 7.8 Hz, 4H), 3.64
(t, J = 7.1 Hz, 4H), 6.64 (d, J = 7.7 Hz, 2H), 6.94 (td,
J = 8.0, 0.7 Hz, 2H), 7.24 (td, J = 7.6, 1.0 Hz, 2H), 7.45 (t,
J = 7.2 Hz, 4H), 7.52 (t, J = 7.1 Hz, 2H), 7.78 (t,
J = 7.2 Hz, 4H), 9.02 (d, J = 7.9 Hz, 2H) ppm; 13C NMR
(100.6 MHz, CDCl3): d = 24.4, 25.6, 27.0, 39.5, 55.9,
107.7, 121.5, 122.3, 127.9, 129.3, 129.9, 132.4, 133.3,
133.7, 139.0, 144.3, 167.8 ppm; HRMS (ESI): [M?Na]?
calcd for C38H38N2O2S2Na 641.2273, found 641.2798.
(E)-1,10-Bis[5-(phenylsulfonyl)pentyl]-[3,30-biindolinyli-
dene]-2,20-dione (10a, C38H38N2O6S2) The mixture of
168 mg
(E)-1,10-bis(5-bromopentyl)-[3,30-biindolinyli-
dene]-2,20-dione (2e, 0.3 mmol) and 164 mg sodium ben-
zenesulfinate (9, 1 mmol) in 5 cm3 DMF was stirred for
8 h at 70 °C. The resulting mixture was extracted with
CH2Cl2 (2 9 10 cm3), washed with 10 cm3 water and the
combined organic layers dried (MgSO4) and concentrated.
The resulting solid was subjected to flash column chro-
matography (silica gel) using petroleum ether–ethyl acetate
(3:1) as an eluent and gave the dione 10a. Dark red pow-
(E)-1,10-Bis[5-(benzo[d]thiazol-2-ylthio)pentyl]-[3,30-biin-
dolinylidene]-2,20-dione (6a, C40H36N4O2S4) A mixture of
168 mg
(E)-1,10-bis(5-bromopentyl)-[3,30-biindolinyli-
dene]-2,20-dione (2e, 0.3 mmol), 167 mg 2-mercaptoben-
zothiazole (5, 1 mmol) and 101 mg triethylamine
(1 mmol) in 6 cm3 CH2Cl2 was heated at reflux with stir-
ring for 6 h. The solvent was removed under reduced
pressure and the residue subjected to silica gel column
chromatography using petroleum spirit–ethyl acetate (4:1)
as eluent to give the dione 6a. Dark red powder; yield 54%;
ꢀ
der; yield 66%; m.p.: 154 °C; IR (KBr): m = 1692, 1604,
1461, 1443, 1417, 1251 1005, 782, 723 cm-1; kmax/nm
1
(e) = 265 (3992), 395 (3439) nm (M-1 cm-1); H NMR
(400.1 MHz, CDCl3): d = 1.41–1.49 (m, 4H), 1.65–1.80
(m, 8H), 3.06 (t, J = 7.8 Hz, 4H), 3.74 (t, J = 7.0 Hz, 4H),
6.73 (d, J = 7.7 Hz, 2H), 7.03 (td, J = 7.9, 0.8, 2H), 7.33
(td, J = 7.6, 0.9, 2H), 7.54 (t, J = 7.2 Hz, 4H), 7.61–7.65
(m, 2H), 7.86–7.88 (m, 4H), 9.10 (d, J = 7.4 Hz, 2H) ppm;
13C NMR (100.6 MHz, CDCl3): d = 22.4, 25.7, 27.0, 39.5,
55.9, 107.7, 121.6, 122.3, 128.0, 129.2, 129.9, 132.4,
133.3, 133.6, 139.0, 144.4, 167.8 ppm; HRMS (ESI):
[M?Na]? calcd for C38H38N2O6S2Na 705.2069, found
705.2079.
ꢀ
m.p.: 109 °C; IR (KBr): m = 1690, 1605, 1465, 1453, 1423,
1355, 1005, 749, 734 cm-1; kmax/nm (e) = 271 (3933), 301
1
(2942) nm (M-1 cm-1); H NMR (400.1 MHz, CDCl3):
d = 1.49–1.55 (m, 4H), 1.66–1.74 (m, 4H), 1.78–1.85 (m,
4H), 3.25 (t, J = 7.3 Hz, 4H), 3.72 (t, J = 7.2 Hz, 4H), 6.70
(d, J = 7.7 Hz, 2H), 6.95 (td, J = 8.1, 0.9 Hz, 2H),
7.17–7.20 (m, 2H), 7.24 (td, J = 7.7, 1.0 Hz, 2H), 7.30 (td,
J = 7.2, 1.1 Hz, 2H), 7.64 (d, J = 7.8 Hz, 2H), 7.76 (d,
J = 8.1 Hz, 2H), 9.10 (d, J = 8.0 Hz, 2H) ppm; 13C NMR
(100.6 MHz, CDCl3): d = 25.1, 26.0, 28.0, 32.2, 38.7,
106.8, 119.8, 120.4, 120.6, 121.2, 123.1, 124.9, 128.9,
131.3, 132.4, 134.1, 143.5, 152.2, 165.9, 166.8 ppm;
HRMS (ESI): [M?H]? calcd for C40H37N4O2S4 733.1799,
found 733.1830.
(3Z,30Z)-3,30-(ethane-1,2-diylidene)bis(indolin-2-one) (12,
C18H12N2O2) To a magnetically stirred solution of 2.00 g
2-oxindole (11, 15.00 mmol) in 8 cm3 ethanol, 1.08 g
glyoxal (40% w/w, 7.50 mmol) and 1 cm3 concentrated
hydrochloric acid were added and the mixture was heated
for 6 h at reflux. After cooling, the mixture was filtered and
the solid was washed with diethyl ether, ethyl acetate, and
cold ethanol to give 12. Red solid; yield 32%; m.p.:
(E)-1,10-Bis[4-(pyrimidin-2-ylthio)butyl]-[3,30-biindolinyli-
dene]-2,20-dione (8a, C32H30N6O2S2) A mixture of 159 mg
(E)-1,10-bis(4-bromobutyl)-[3,30-biindolinylidene]-2,20-
dione (2m, 0.3 mmol), 112 mg 2-mercaptopyrimidine (7,
1 mmol) and 101 mg Et3N (1 mmol) in 5 cm3 DMF was
stirred for 6 h at 80 °C. The resulting mixture was
extracted with CH2Cl2 (2 9 10 cm3), washed with 10 cm3
water and the combined organic layers dried (MgSO4) and
concentrated. The resulting residue was subjected to flash
column chromatography (silica gel) using petroleum spirit–
dichloromethane (1:3) as an eluent to give the dione 8a.
Dark red powder; yield 58%; m.p.: 172 °C; IR (KBr):
ꢀ
[ 300 °C; IR (KBr): m = 1689, 1601, 1464, 1351, 1176,
1
749, 726 cm-1; H NMR (400.1 MHz, CDCl3): d = 6.85
(d, J = 7.7 Hz, 2H), 4.99 (t, J = 7.4 Hz, 2H), 7.27 (t,
J = 7.6 Hz, 2H), 7.50 (d, J = 7.4 Hz, 2H), 8.79 (s, 2H),
10.68 (s, NH) ppm; 13C NMR (100.6 MHz, CDCl3):
d = 110.4, 121.3, 122.1, 123.6, 127.6, 131.3, 131.8, 142.8,
168.4 ppm; HRMS (ESI): [M?H]? calcd for C18H13N2O2
289.0977, found 289.0981.
ꢀ
m = 1690, 1604, 1465, 1453, 1423, 1005, 762, 749,
718 cm-1; kmax/nm (e) = 247 (4000), 278 (4020) nm
123

Design and synthesis of new functionalized isoindigo and (3Z,30Z)-3,30-(ethane-1,2-diylidene)…
Acknowledgements We thank the Centre for Molecular Biosciences
at the University of Wollongong for support.
General procedure for the synthesis of 13a–13c
To a magnetically stirred solution of (3Z,30Z)-3,30-(ethane-
1,2-diylidene)bis(indolin-2-one) (12, 0.5 mmol) in 3 cm3
DMF, sodium methoxide (1.1 mmol) was added in 2 cm3
DMF at room temperature. The reaction mixture was stir-
red for 30 min, and then the alkyl bromide (3 mmol) was
added and the mixture stirred for 8 h at 45 °C. The mixture
was poured into 10 cm3 H2O, extracted with 20 cm3
CH2Cl2, dried (MgSO4), and the solvent was removed
under reduced pressure. The residue was subjected to silica
gel column chromatography using petroleum spirit–ethyl
acetate mixture as eluent.
References
1. Garcia-Frutos EM (2013) J Mater Chem C 1:3633
2. Ogawa S (2015) Organic electronics materials and devices.
Springer, Berlin
3. Burroughes JH, Bradey DDC, Brown AR, Marks RN, Mackay K,
Friend RH, Burns PL, Holmes AB (1990) Nature 347:539
4. Tsao HN, Cho DM, Park I, Hansen MR, Mavrinskiy A, Yoon
DY, Graf R, Pisula W, Spiess HW, Mullen K (2011) J Am Chem
Soc 133:2605
5. Zaumseil J, Sirringhaus H (2007) Chem Rev 107:1296
6. Yu G, Gao J, Hummelen JC, Wudl F, Heeger AJ (1995) Science
270:1789
7. Mazzio KA, Luscombe CK (2015) Chem Soc Rev 44:78
8. Lin Y, Zhao J, Li Z, Mu C, Ma W, Hu H, Jiang K, Lin H, Ade H,
Yani H (2014) Nat Commun 5:5293
9. Jou J-H, Kumar S, Agrawal A, Li TH, Sahoo S (2015) J Mater
Chem C 3:2974
10. Kraft A, Grimsdale AC, Holmes AB (1998) Angew Chem Int Ed
37:402
11. Coughlin JE, Henson ZB, Welch GC, Bazan GC (2014) Acc
Chem Res 47:257
(3Z,30Z)-3,30-(Ethane-1,2-diylidene)bis(1-isopropylindolin-2-
one) (13a, C24H24N2O2) Red powder; m.p.: 184 °C; IR
-1
ꢀ
(KBr): m = 1689, 1601, 1464, 1351, 1176, 749, 726 cm
;
1
kmax/nm (e) = 228 (3018), 386 (3428) nm (M-1 cm-1); H
NMR (400.1 MHz, CDCl3): d = 1.52 (d, J = 7.0 Hz, 12H),
4.67 (sep, J = 6.9 Hz, 2H), 6.94 (d, J = 7.9 Hz, 2H), 7.00
(td, J = 7.5, 0.7 Hz, 2H), 7.22–7.27 (m, 2H), 7.63 (dd,
J = 7.5, 0.5 Hz, 2H), 8.98 (s, 2H) ppm; 13C NMR
(100.6 MHz, CDCl3): d = 19.5, 43.4, 109.7, 121.3, 121.7,
123.6, 128.5, 130.1, 131.1, 142.1, 166.8 ppm; HRMS
(ESI): [M?Na]? calcd for C24H24N2O2Na 395.1735, found
395.1723.
12. Patel DG, Feng F, Ohnishi YY, Abboud KA, Hirata S, Schanze
KS, Reynolds JR (2012) J Am Chem Soc 134:2599
13. Li C, Wonneberger H (2012) Adv Mater 24:613
14. Zhou N, Guo X, Ortiz RP, Li S, Zhang S, Chang RPH, Facchetti
A, Marks TJ (2012) Adv Mater 24:2242
15. Sommer M (2014) J Mater Chem C 2:3088
16. Qu S, Tian H (2012) Chem Commun 48:3039
17. Stalder R, Mei J, Graham KR, Estrada LA, Reynolds JR (2014)
Chem Mater 26:664
18. Lei T, Wang JY, Pei J (2014) Acc Chem Res 47:1117
19. Wang E, Mammo W, Andersson MR (2014) Adv Mater 26:1801
20. Lei T, Gao Y, Fan Y, Liu CJ, Yuan SC, Pei J (2011) J Am Chem
Soc 133:6099
21. Ho CC, Chang SY, Huang TC, Chen CA, Liao HC, Chen YF, Su
WF (2013) Polym Chem 4:5351
22. Mei J, Graham KR, Stalder R, Reynolds JR (2010) Org Lett
12:660
23. Bogdanov AV, Yusupova GC, Romannova IP, Latypov SK,
Krivolapov DB, Mironov VF, Sinyashin OG (2013) Synthesis
45:668
24. Bogdanov AV, Kuzmicheva TA, Mironov VF (2017) Russ J Org
Chem 53:626
(3Z,30Z)-3,30-(Ethane-1,2-diylidene)bis[1-[(cyclohex-2-en-1-
yl)methyl]indolin-2-one] (13b, C30H328N2O2) Red powder;
ꢀ
m.p.: 188 °C; IR (KBr): m = 1690, 1600, 1464, 1351, 1176,
749, 670 cm-1; kmax/nm (e) = 279 (3754), 404 (3964) nm
(M-1 cm-1);
1H
NMR
(400.1 MHz,
CDCl3):
d = 1.71–1.78 (m, 2H), 1.89–1.95 (m, 6H), 2.09–2.11 (m,
4H), 5.09–5.12 (m, 2H), 5.58 (d, J = 12.0 Hz, 2H),
5.93–5.96 (m, 2H), 6.89–6.94 (m, 4H), 7.12 (td, J = 7.7,
1.1 Hz, 2H), 7.53 (d, J = 7.0 Hz, 2H), 8.93 (s, 2H) ppm;
13C NMR (100.6 MHz, CDCl3): d = 21.8, 24.5, 26.0, 47.9,
110.8, 121.1, 121.8, 123.5, 127.5, 128.7, 130.0, 130.9,
131.1, 142.1, 166.9 ppm; HRMS (ESI): [M?Na]? calcd
for C30H328N2O2Na 471.2048, found 471.2062.
25. Bogdanov AV, Mironov VF, Musin LI, Musin RZ (2010) Syn-
thesis 19:3268
26. Sasada T, Kobayashi F, Sakai N, Konakahara T (2009) Org Lett
11:2161
27. Agarwal N, Raghuwanshi SK, Upadhyay DN, Shukla PK, Ram
VJ (2000) Bioorg Med Chem Lett 10:703
28. Lee HW, Bok YK, Joong BA (2005) Eur J Med Chem 40:862
29. Simpkins NS (1993) Sulfone in organic synthesis. Pergamon
Press, Oxford
30. Sasikumar TK, Qiang L, Burnett DA, Cole D, Xu R, Li HM,
Greenlee WJ, Clader J, Zhang LL, Hyde L (2010) Bioorg Med
Chem Lett 20:3632
31. Johnson AW, Katner AS (1965) J Chem Soc 256:1455
32. Chen SY, Sun B, Guo C, Hong W, Meng YZ, Li YN (2014)
Chem Commun 50:6509
(3Z,30Z)-3,30-(Ethane-1,2-diylidene)bis[1-(4-bromobutyl)in-
dolin-2-one] (13c, C26H26Br2N2O2) Red powder; m.p.:
ꢀ
156 °C; IR (KBr): m = 1690, 1608, 1465, 1356, 1331,
1150, 1095, 775, 743 cm-1; kmax/nm (e) = 234 (3952), 413
1
(4000) nm (M-1 cm-1); H NMR (400.1 MHz, CDCl3):
d = 1.85–1.98 (m, 8H), 3.47 (t, J = 6.3 Hz, 4H), 3.79 (t,
J = 6.6 Hz, 4H), 6.81 (d, J = 7.8 Hz, 2H), 7.03 (td,
J = 7.6, 0.8 Hz, 2H), 7.27–7.31 (m, 2H), 7.63 (dd, J = 7.5,
0.4 Hz, 2H), 8.97 (s, 2H) ppm; 13C NMR (100.6 MHz,
CDCl3): d = 26.2, 29.8, 33.0, 38.6, 108.3, 121.4, 122.3,
123.3, 128.8, 130.5, 130.9, 142.7, 167.1 ppm; HRMS
79
26
(ESI): [M?Na]? calcd for C26H Br2N2O2Na 579.0259,
33. Trost BM, Osipov M (2013) Angew Chem Int Ed 52:9176
found 579.0277.
123