Synthesis and photochromism of functionalized benzothiophene-based fulgides and fulgimides

Article abstract of DOI:10.1007/s11172-010-0099-y

Earlier unknown fulgides and the corresponding functionalized fulgimides containing a primary amino group were obtained. Their photochromism was examined using spectroscopic methods.

Full text of DOI:10.1007/s11172-010-0099-y

Russian Chemical Bulletin, International Edition, Vol. 59, No. 2, pp. 446—451, February, 2010
446
Synthesis and photochromism of functionalized
benzothiopheneꢀbased fulgides and fulgimides
S. I. Luyksaar, V. A. Migulin, B. V. Nabatov, and M. M. Krayushkin
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 137 6939. Eꢀmail: luyksaar@gmail.com
Earlier unknown fulgides and the corresponding functionalized fulgimides containing
a primary amino group were obtained. Their photochromism was examined using spectroscopic
methods.
Key words: benzothiophenes, Stobbe condensation, fulgides, fulgimides, photochromism.
Scheme 1
Photochromic fulgides and fulgimides have high faꢀ
tigue resistances and are thermally and chemically stable
in both open and closed forms. These properties make
them convenient materials for designing optical storage
devices, molecular switches, dynamic chemosensors and
biosensors, and biological activity controllers.1—4
In the literature, this class of photochromic compounds
is mainly represented by thiophene, furan, and indole deꢀ
rivatives. It should be noted that only two fulgides with an
unsubstituted benzothiophene fragment have been deꢀ
scribed to date,5,6 while their analogs with a substituted
benzene ring have not been documented at all.
The goal of the present work was to develop methods
for the synthesis of (1) photochromic fulgides containing
a 5ꢀsubstituted benzothiophene fragment and (2) the corꢀ
responding fulgimides with an unsubstituted primary amiꢀ
no group and to examine their photochromic characterisꢀ
tics. The presence of the reactive functional group enables
the fulgimides obtained to be modified or be introduced as
a photochromic fragment into other compounds, which
extends the area of application of these photochromes.
R = Me (1b, 2a, 4a), Cl (1c, 2b, 4b), Br (1d, 2c, 4c)
The Friedel—Crafts acylation of compounds 1a—d
with acetyl chloride gave 3ꢀacetylꢀ2ꢀmethylbenzo[b]thiopheꢀ
nes 5a—d (Scheme 2). Ketones 5a—c were used in the
Stobbe condensation with diethyl isopropylidenesuccinate
6.6 Treatment of the reaction mixture (without isolation or
purification of intermediate fulgenates 7a—c and the corꢀ
responding fulgenic acids 8a—c) with acetyl chloride afforꢀ
ded benzothienylfulgides 9a—c in 11—19% yields with
respect to the corresponding 3ꢀacetylbenzothiophenes (see
Scheme 2).
Unlike fulgide 9c, its bromo analog was not obtained
because the Stobbe condensation of 5ꢀbromoꢀ2ꢀmethylꢀ
benzo[b]thiophene 1d produces a complex mixture of prodꢀ
ucts. The structures of fulgides 9a—c were confirmed by
1H NMR and mass spectra and elemental analysis data.
The 1H NMR spectra show singlets for the methyl groups
at δH 2.15—2.51 and signals for the aromatic protons of
the benzothiophene fragment at δH 7.11—7.68.
Results and Discussion
Earlier unknown fulgides and fulgimides were obtained
from various 2ꢀmethylbenzo[b]thiophenes. For instance,
2ꢀmethylbenzo[b]thiophene (1a) was prepared by lithiaꢀ
tion of commercial benzothiophene followed by alkylaꢀ
tion with dimethyl sulfate according to a known proceꢀ
dure.7 5ꢀSubstituted 2ꢀmethylbenzo[b]thiophenes 1b—d
were prepared by reactions of appropriate benzenethiols
2a—c with 2ꢀbromoꢀ1,1ꢀdiethoxypropane (3) followed by
thermal cyclization of intermediate sulfides 4a—c in polyꢀ
phosphoric acid (Scheme 1). The yields of 2ꢀmethylꢀ
benzo[b]thiophenes 1b—d range from 54 to 69% with reꢀ
spect to the starting mercaptans.
Fulgides 9a—c were used in reactions with NꢀBocꢀ
1,4ꢀphenylenediamine 10 as described earlier8 (Scheme 3).
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 436—441, February, 2010.
1066ꢀ5285/10/5902ꢀ0446 © 2010 Springer Science+Business Media, Inc.

Aminoꢀcontaining fulgimides
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 2, February, 2010
447
Scheme 2
1, 5, 7—9: R = H (a), Me (b), Cl (c); 1, 5: R = Br (d)
Scheme 3
R = H (a), Me (b), Cl (c)

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Russ.Chem.Bull., Int.Ed., Vol. 59, No. 2, February, 2010
Luyksaar et al.
On reflux in benzene for 15—20 h, the resulting mixꢀ
pear at δH 1.9—2.5, while the EꢀCH3 group of the isoproꢀ
pylidene fragment in the Eꢀisomer resonates at δH 1.3—1.4
because of the shielding effect of the benzothiophene sysꢀ
tem characteristic only of Eꢀisomers of fulgides and fulgimꢀ
ides. The signals for the methyl groups of all the benꢀ
zothiopheneꢀcontaining fulgides 9a—c and fulgimides
14a—c appear at δH 2.11—2.55, thus suggesting their
Zꢀconfiguration.
We examined the photochromism of fulgides 9a—c
and fulgimides 14a—c in acetonitrile using spectroscopic
methods (Table 1). Note that spectroscopic data on the
photochromism of unsubstituted fulgide 9a in toluene are
available.6 We recorded electronic absorption spectra of
this fulgide in acetonitrile for convenient comparison of
its properties with the spectroscopic characteristics of
fulgides 9b—c and fulgimides 14a—c.
All the fulgides and fulgimides obtained are photoꢀ
chromes. When their solutions are exposed to monochroꢀ
mated UV light (313 nm), their spectra contain new broad
bands in the visible range. The corresponding peaks appear
at 480—500 nm (see Table 1). This suggests UVꢀinduced
formation of the close (cyclic) forms of these compounds.12
For the starting (open) forms of fulgides 9a—c, the
absorption bands are similar in shape and peak position
(see Table 1). Introduction of both electronꢀreleasing (Me)
and electronꢀwithdrawing substituents (Cl) significantly
ture of crude amic acids 11a—c and 12a—c was dissolved
in THF and stirred with N,N´ꢀcarbonyldiimidazole (CDI)
(1.1 equiv.) at room temperature for 5 h. At a final step,
the Bocꢀprotection was eliminated from intermediate
NꢀBocꢀamino fulgimides 13a—c under the action of 5 M
HCl in ethanol followed by alkalization with a methanolic
solution of ammonia. The yields of Nꢀ(4ꢀaminopheꢀ
nyl)fulgimides 14a—c were 65—71% with respect to the
starting fulgide.
The structures of products 14a—c were confirmed by
1
mass and H NMR spectra and elemental analysis data.
1
The H NMR spectra contain singlets for the methyl
groups at δH 2.11—2.55 and broadened singlets for the
amino group at δH 3.56—5.24. Signals for the aromatic
protons in the phenyl substituents appear as doublets at
δH 6.59—7.49.
It is known1 that fulgides and fulgimides can exist as
three isomers (Scheme 4).
Scheme 4
Table 1. Photochromism of fulgides and fulgimides
max
Соедиꢀ
нение
λ (AA)a
λ
AB
А
B
nm
9a
341b
500
490
0.060
0.070
231 (1.040), 268 (0.613),
336 (0.137)
9b
234 (1.305), 268 (0.759),
338 (0.161)
237 (1.538), 270 (0.726),
326 (0.184)
235 (1.770), 262 sh,
324 sh
241 (1.245), 266 (1.153),
328 sh
500
490
482
491
479
0.104
0.060
0.192
0.014
0.203
9c
X = O, NR´
14a
14b
14c
All three isomers are in photochemical equilibrium but
only the Eꢀ and Cꢀisomers are involved in photochromic
transformations. The geometry of the Zꢀisomer precludes
its cyclization and an additional portion of the UV light
energy is required for the Z—E isomerization, which inevꢀ
itably lowers the yield of cyclic photoproducts because
E—Z isomerization is a parallel channel for deactivation
of the excitedꢀstate energy. The Zꢀ or Eꢀconfiguration of
fulgides and fulgimides containing an exocyclic isopropylꢀ
idene substituent can easily be determined from the
1H NMR spectra: this problem was discussed in detail
earlier.9—11 The configurations of such fulgides and fulgimꢀ
ides are determined by the chemical shifts of the signals
for the methyl groups in the isopropylidene fragment. For
the Zꢀisomers of fulgides and fulgimides, these signals apꢀ
241 (2.050), 266 sh,
322 sh
Note: λ and AA are the absorption peak wavelengths and the
corresponding optical densities of the starting (open) form, reꢀ
A
spectively; λ is the peak wavelength of the longerꢀwavelength
B
absorption of the colored (cyclic) form; ABmax is the optical denꢀ
sity of the solution (for a 1ꢀcmꢀthick layer) at the peak waveꢀ
length for the cyclic form in the photostationary state induced by
UV irradiation with monochromatized light (313 nm).
a
The measurements were conducted in acetonitrile
(C = 5•10–5 mol L–1).
b Data from Ref. 6. The measurements were conducted in toluꢀ
ene. The cited ABmax value is calculated for C = 5•10–5 mol L–1
.

Aminoꢀcontaining fulgimides
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 2, February, 2010
449
does not change the band shape or position, as compared
to the open form of unsubstituted fulgide 9a. For instance,
the band at 230 nm for compounds 9a—c shows a slight
bathochromic shift (by 3 nm) and the longꢀwavelength
band for compound 9c shows a hypsochromic shift (by
10 nm) relative to the same band for compound 9a. The
electronic absorption spectrum of compound 9a, which is
typical of this group of compounds, is displayed in Fig. 1, a.
The spectra of fulgimides 14a—c are also similar to
each other but contain no distinct absorption bands at
270—330 nm, in contrast to the spectra of the correspondꢀ
ing fulgides. The electronic absorption spectrum of comꢀ
pound 14a, which is typical of this group of compounds, is
displayed in Fig. 1, b.
As with the open forms of fulgides, the presence of
substituents virtually does not affect the band shape and
position in the spectra of the cyclic forms of fulgides 9b—c
compared to unsubstituted fulgide 9a. Note that the longꢀ
erꢀwavelength of the cyclic form of fulgide 9b (containing
an electronꢀreleasing substituent) shows a bathochromic
shift by 10 nm relative to the corresponding band of comꢀ
pounds 9a,c.
presence of the substituents makes insignificant changes
in the spectra of these photochromes.
Experimental
1
H NMR spectra were recorded on Bruker WMꢀ250 (250 MHz)
and Bruker AM300 spectrometers (300 MHz) in CDCl3
and DMSOꢀd6; mass spectra (EI) were recorded on a Finniꢀ
gan MAT instrument (EI, 70 eV). Melting points were measured
on a Boetius hotꢀstage microscope and are given uncorrected.
The course of the reaction was monitored, and the purity of
the compounds obtained was checked, by TLC on Merck 60
F254 plates.
Commercial benzo[b]thiophene, potassium tertꢀbutoxide,
and N,N´ꢀcarbonyldiimidazole (Acros) were used. Diethyl isoꢀ
propylidenesuccinate 6 was prepared by condensation of diethyl
succinate with acetone in the presence of potassium tertꢀbutoxꢀ
ide.13 2ꢀMethylbenzo[b]thiophene (1a),7 3ꢀacetylꢀ2ꢀmethylꢀ
benzo[b]thiophene (5a),14 and NꢀBocꢀ1,4ꢀphenylenediamine
10 15 were prepared according to known procedures.
The electronic absorption spectra of the compounds obtained
were recorded in solutions on a Lambda 650 twoꢀchannel specꢀ
trophotometer (Perkin Elmer). In photochemical studies, all soꢀ
lutions were exposed to UV light with λ = 313 or 365 nm. The
light emitted by a DRKꢀ120 mercuryꢀquartz lamp as part of an
OIꢀ18A luminescent lighter (LOMO) was monochromated with
a set of glass compound light filters. Measurements were carried
out in quartz cells (10 mm thick) in the following modes: monoꢀ
chromator step 1 nm, slit width 3 nm, averaging over 3—5 points
in each step.
The absorption spectra of fulgimides 14 show a slight
hypsochromic shift (~10 nm) of the absorption peaks of
the cyclic forms compared to the corresponding fulgides 9
(Table 1). In addition, solutions of the cyclic forms
of fulgimides 14a,c in the photostationary state have
max
higher optical densities DB
than the corresponding
fulgides; the opposite pattern is observed for the pair
fulgimide 14b/fulgide 9b. Fulgimides 14a,c are most phoꢀ
tosensitive among the compounds studied, which is eviꢀ
dent from the highest optical densities at the absorption
peak wavelength for their cyclic forms in the photostaꢀ
tionary state.
Electronic absorption spectra were recorded in acetonitrile
(99% purity, Acros). The concentration of all solutions was
5•10–5 mol L–1
.
Synthesis of 5ꢀsubstituted 2ꢀmethylbenzo[b]thiophenes 1b—d
(general procedure). Potassium tertꢀbutoxide (6.4 g, 57.1 mmol)
was dissolved in cold anhydrous ethanol (50 mL). Appropriate
benzenethiol 2a—c (51.9 mmol) was added in one portion and
the mixture was homogenized by stirring it for 2 h. Then
2ꢀbromoꢀ1,1ꢀdiethoxypropane 3 16 (13.2 g, 62.3 mmol) was addꢀ
ed and the reaction mixture was refluxed for 15—25 h until the
starting compound was completely consumed (monitoring by
TLC). The solvent was removed and the residue was diluted with
CH2Cl2 and water. Organic material from the aqueous layer was
extracted with CH2Cl2 (2×50 mL). The combined organic phasꢀ
es were washed with water and brine, dried with anhydrous
Na2SO4, filtered, and concentrated. Sulfides 4b—d isolated as
light brown oils were employed in the next step without addiꢀ
tional purification. Sulfides 4b—d were added in small portions
to a stirred boiling suspension of polyphosphoric acid (30 g) in
chlorobenzene (120 mL) for 1 h. The reaction mixture was reꢀ
fluxed for 8—10 h until the starting compound was completely
consumed (monitoring by TLC). On cooling, the organic layer
was separated by decanting. The brown residue was dissolved in
water and the product was extracted with CH2Cl2 (3×75 mL).
The combined organic phases were washed with water, dried
over Na2SO4, filtered, and concentrated. The residue was subꢀ
limed in vacuo (1.2 Torr) to give the corresponding 2ꢀmethylꢀ
benzo[b]thiophene.
Thus, we obtained fulgides and fulgimides containing
the 5ꢀsubstituted benzothiophene ring and found that the
A
1.0
0.8
0.6
0.4
0.2
2
1
0
250 300 350 400 450 500 550 600 λ/nm
Fig. 1. Electronic absorption spectra A(λ) of compounds 9a (a)
and 14a (b) in acetonitrile at 298 K for a 1ꢀcmꢀthick layer:
(1) the starting open form and (2) the photostationary state
induced by UV irradiation with monochromatized light (313 nm).
2,5ꢀDimethylbenzo[b]thiophene (1b). Yield 4.5 g (54%), white
powder, m.p. 43—45 °C (cf. Ref. 17: m.p. 45—46 °C).

450
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 2, February, 2010
Luyksaar et al.
5ꢀChloroꢀ2ꢀmethylbenzo[b]thiophene (1c). Yield 6.5 g (69%),
light petroleum (35 mL) was added dropwise. On cooling, the
crystals that formed were filtered off and washed with light peꢀ
troleum.
4ꢀIsopropylideneꢀ3ꢀ[Zꢀ1ꢀ(2ꢀmethylꢀ3ꢀbenzothienyl)ethylꢀ
idene]furanꢀ2,5ꢀdione (9a). Yield 19%, white crystals, m.p.
174—176 °C (cf. Ref. 6: m.p. 173—176 °C).
3ꢀ[Zꢀ1ꢀ(2,5ꢀDimethylꢀ3ꢀbenzothienyl)ethylidene]ꢀ4ꢀ(isoproꢀ
pylidene)furanꢀ2,5ꢀdione (9b). Yield 15%, m.p. 161—163 °C.
1H NMR (CDCl3), δ: 2.16 (s, 3 H, CH3); 2.22 (s, 3 H, CH3);
2.42 (s, 3 H, CH3); 2.43 (s, 3 H, CH3); 2.51 (s, 3 H, CH3); 7.11
(m, 2 H, Hthioph); 7.64 (d, 1 H, Hthioph, J = 8.1 Hz). MS, m/z
(Irel (%)): 326 [M]+ (100). Found (%): C, 69.88; H, 5.43; S, 9.75.
C19H18O3S. Calculated (%): C, 69.91; H, 5.56; S, 9.82.
3ꢀ[Zꢀ1ꢀ(5ꢀChloroꢀ2ꢀmethylꢀ3ꢀbenzothienyl)ethylidene]ꢀ4ꢀ
(isopropylidene)furanꢀ2,5ꢀdione (9c). Yield 11%, m.p. 187—189 °C.
1H NMR (CDCl3), δ: 2.18 (s, 3 H, CH3); 2.21 (s, 3 H, CH3);
2.45 (s, 3 H, CH3); 2.50 (s, 3 H, CH3); 7.30 (m, 2 H, Hthioph);
7.68 (d, 1 H, Hthioph, J = 8.3 Hz). MS, m/z (Irel (%)): 346 [M]+
(100). Found (%): C, 62.36; H, 4.31; S, 9.26. C18H15Cl3S. Calꢀ
culated (%): C, 62.34; H, 4.36; S, 9.24.
Synthesis of aminophenylfulgimides 14a—c (general proceꢀ
dure). A solution of fulgide 9 (7.2 mmol) and NꢀBocꢀ1,4ꢀpheꢀ
nylenediamine 10 (1.57 g, 7.54 mmol) in benzene (50 mL) was
refluxed for 15—20 h. The solvent was removed on a rotary
evaporator and the residue was dissolved in THF (50 mL). Then
N,N´ꢀcarbonyldiimidazole (1.28 g, 7.9 mmol) was added and
the reaction mixture was stirred at room temperature for 5 h and
concentrated on a rotary evaporator. The residue was dissolved
with stirring in a 5 M methanolic solution of HCl (75 mL) and
left at room temperature for 12 h. The reaction mixture was
concentrated to dryness on a rotary evaporator and the residue
was dissolved in methanol (30 mL) and alkalized with a 5 M
methanolic solution of ammonia (10 mL). The resulting solution
was concentrated to dryness on a rotary evaporator and the resiꢀ
due was diluted with water (100 mL). The product was extracted
with ethyl acetate (2×30 mL) and the organic layer was separatꢀ
ed, dried over Na2SO4, and concentrated. The resulting light
yellow oil solidified slowly. Recrystallization from ethyl acetꢀ
ate—hexane gave 4ꢀaminophenylfulgimides 14a—c.
white powder, m.p. 78—82 °C (cf. Ref. 17: m.p. 79.5 °C).
5ꢀBromoꢀ2ꢀmethylbenzo[b]thiophene (1d). Yield 7.2 g (61%),
white powder, m.p. 93—95 °C. 1H NMR (CDCl3), δ: 2.62
(s, 3 H); 6.92 (s, 1 H); 7.35 (dd, 1 H, J1 = 8.3 Hz, J2 = 2.0 Hz);
7.61 (d, 1 H, J1 = 8.3 Hz); 7.79 (d, 1 H, J2 = 2.0 Hz). Found (%):
C, 47.45; H, 3.09; S, 14.18. C9H7BrS. Calculated (%): C, 47.60;
H, 3.11; S, 14.12.
Synthesis of 3ꢀacetylꢀ2ꢀmethylbenzo[b]thiophenes 5a—d
(general procedure). Benzothiophene 1a—d (0.011 mol) and
acetyl chloride (1.29 g, 0.016 mol) were dissolved in dry benzene
(100 mL) and the mixture was cooled to 5 °C. Then a solution of
SnCl4 (4.17 g, 0.016 mol) in dry benzene (30 mL) was added
dropwise for 30 min. The reaction mixture was stirred at room
temperature for 3 h and acidified with cold 10% aqueous HCl
(50 mL). The organic layer was separated, dried over Na2SO4,
and concentrated in vacuo. The residue solidified slowly. Reꢀ
crystallization from hexane gave 3ꢀacetylꢀ2ꢀmethylbenzo[b]ꢀ
thiophenes 5a—d.
3ꢀAcetylꢀ2ꢀmethylbenzo[b]thiophene (5a). Yield 1.63 g (86%),
white crystals, m.p. 68—70 °C (cf. Ref. 14: m.p. 69—70 °C).
3ꢀAcetylꢀ2,5ꢀdimethylbenzo[b]thiophene (5b). Yield 1.73 g
1
(77%), white crystals, m.p. 74—76 °C. H NMR (CDCl3), δ:
2.48 (s, 3 H); 2.56 (s, 3 H); 2.68 (s, 3 H); 7.17 (dd, 1 H, J1 = 8.1 Hz,
J2 = 2.0 Hz); 7.61 (d, 1 H, J1 = 8.1 Hz); 8.00 (d, 1 H, J2 = 2.1 Hz).
Found (%): C, 70.49; H, 5.89; S, 15.65. C12H12OS. Calculatꢀ
ed (%): C, 70.55; H, 5.92; S, 15.70.
3ꢀAcetylꢀ5ꢀchloroꢀ2ꢀmethylbenzo[b]thiophene (5c). Yield
1.73 g (81%), white crystals, m.p. 92—95 °C. 1H NMR (CDCl3),
δ: 2.46 (s, 3 H); 2.55 (s, 3 H); 7.14 (dd, 1 H, J1 = 8.3 Hz, J2 = 2.1 Hz);
7.61 (d, 1 H, J = 8.3 Hz); 8.38 (d, 1 H, J = 2.1 Hz). Found (%):
C, 58.63; H, 4.01; S, 14.15. C11H9ClOS. Calculated (%):
C, 58.80; H, 4.04; S, 14.27.
3ꢀAcetylꢀ5ꢀbromoꢀ2ꢀmethylbenzo[b]thiophene (5d). Yield
2.76 g (93%), white crystals, m.p. 94—96 °C. 1H NMR (CDCl3),
δ: 2.63 (s, 3 H); 2.78 (s, 3 H); 7.43 (dd, 1 H, J1 = 8.3 Hz, J2 = 2.0 Hz);
7.57 (d, 1 H, J = 8.3 Hz); 8.41 (d, 1 H, J = 2.0 Hz). Found (%):
C, 49.00; H, 3.33; S, 11.85. C11H9BrOS. Calculated (%):
C, 49.09; H, 3.37; S, 11.91.
Synthesis of fulgides 9a—c (general procedure). A 500ꢀmL
roundꢀbottomed flask fitted with a mechanical stirrer, a dropꢀ
ping funnel, and a reflux condenser was charged with potassium
tertꢀbutoxide (11 g, 0.098 mol) and anhydrous toluene (250 mL).
The resulting suspension was vigorously stirred for 30 min while
adding dropwise a solution of appropriate 3ꢀacetylꢀ2ꢀmethylꢀ
benzothiophene 5a—c (0.093 mol) and diethyl isopropylideneꢀ
succinate (6) (20 g, 0.093 mol) in dry toluene (50 mL). The
reaction mixture was stirred at room temperature for 8 h, poured
into water (300 mL), and stirred for 10 min. The aqueous layer
was separated and organic material was extracted with toluene
(2×50 mL). The extract was acidified with conc. HCl to pH 1
and the product was extracted with ethyl acetate (4×75 mL). The
extract was concentrated on a rotary evaporator to a brown oil,
which was diluted with ethanol (70 mL) and water (150 mL) and
alkalized with KOH (15 g, 0.27 mol). The mixture was refluxed
for 6 h, evaporated to dryness, diluted with water (150 mL), and
acidified with conc. HCl (20 mL). The resulting viscous dark
brown oil was dissolved in CH2Cl2 (50 mL) and acetyl chloride
(70 mL). The reaction mixture was stirred at room temperature
for 3 h and concentrated to dryness on a rotary evaporator. The
residue was dissolved in boiling chloroform (15 mL), whereupon
1ꢀ(4ꢀAminophenyl)ꢀ4ꢀisopropylideneꢀ3ꢀ[Zꢀ1ꢀ(2ꢀmethylꢀ3ꢀ
benzothienyl)ethylidene]pyrrolidineꢀ2,5ꢀdione (14a). Yield 68%,
colorless crystals, m.p. 239—241 °C. 1H NMR (CDCl3), δ: 2.16
(s, 3 H, CH3); 2.21 (s, 3 H, CH3); 2.45 (s, 3 H, CH3); 2.52 (s, 3 H,
CH3); 3.58 (br.s, 2 H, NH2); 6.59 (d, 2 H, Har, J = 7.5 Hz);
7.0 (d, 2 H, Har, J = 7.8 Hz); 7.12—7.48 (m, 3 H, Hthioph); 7.75
(d, 1 H, Hthioph, J = 9.1 Hz). MS, m/z (Irel (%)): 402 [M]+ (100).
Found (%): C, 71.65; H, 5.53; N, 6.80. C24H22N2O2S. Calculatꢀ
ed (%): C, 71.62; H, 5.51; N, 6.96.
1ꢀ(4ꢀAminophenyl)ꢀ3ꢀ[Zꢀ1ꢀ(2,5ꢀdimethylꢀ3ꢀbenzothienyl)ꢀ
ethylidene]ꢀ4ꢀ(isopropylidene)pyrrolidineꢀ2,5ꢀdione (14b). Yield
65%, colorless crystals, m.p. 195—198 °C. 1H NMR (CDCl3), δ:
2.18 (s, 3 H, CH3); 2.26 (s, 3 H, CH3); 2.43 (s, 3 H, CH3); 2.45
(s, 3 H, CH3); 2.55 (s, 3 H, CH3); 3.56 (br.s, 2 H, NH2); 7.14
(m, 2 H, Hthioph); 7.66 (d, 1 H, Hthioph, J = 8.1 Hz). MS, m/z
(Irel (%)): 416 [M]+ (100). Found (%): C, 71.92; H, 5.75; N, 6.61.
C25H24N2O2S. Calculated (%): C, 72.09; H, 5.81; N, 6.73.
1ꢀ(4ꢀAminophenyl)ꢀ3ꢀ[Zꢀ1ꢀ(5ꢀchloroꢀ2ꢀmethylꢀ3ꢀbenzothiꢀ
enyl)ethylidene]ꢀ4ꢀ(isopropylidene)pyrrolidineꢀ2,5ꢀdione (14c).
Yield 71%, colorless crystals, m.p. 291—293 °C. 1H NMR
(DMSOꢀd6), δ: 2.11 (s, 3 H, CH3); 2.12 (s, 3 H, CH3); 2.39 (s, 3 H,
CH3); 2.42 (s, 3 H, CH3); 5.24 (br.s, 2 H, NH2); 6.51 (d, 2 H,

Aminoꢀcontaining fulgimides
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 2, February, 2010
451
Har, J = 8.0 Hz); 6.78 (d, 2 H, Har, J = 8.0 Hz); 7.30 (d, 1 H,
8. M. M. Krayushkin, F. M. Stoyanovich, S. V. Shorunov, Menꢀ
deleev Commun., 2003, 13, 192.
9. A. Glaze, S. Harris, H. Heller, W. Johncock, S. Oliver,
P. Strydom, J. Whittall, J. Chem. Soc., Perkin Trans. I,
1985, 957.
J = 8.3 Hz); 7.49 (d, 1 H, J = 8.3 Hz); 7.90 (d, 1 H, Hthioph
,
J = 8.3 Hz). MS, m/z (Irel (%)): 436 [M]+ (100). Found (%):
C, 65.83; H, 4.62; N, 6.29. C24H21ClN2O2S. Calculated (%):
C, 65.97; H, 4.84; N, 6.41.
10. J. Kiji, T. Okano, H. Kitamura, Y. Yokoyama, S. Kubota,
Y. Kurita, Bull. Chem. Soc. Jpn, 1995, 68, 616.
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16. F. Bellesia, M. Boni, F. Ghelfi, U. M. Pagnoni, Gazz. Chim.
Ital., 1993, 123, 629.
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Received February 17, 2009;
in revised form December 22, 2009