Photochromic dihetarylethenes 19. * Synthesis of 1, 2-dihetarylethenes on the basis of thieno[3,2-b]pyrroles linked by a maleimide bridge

Article abstract of DOI:10.1023/A:1026069007586

New photochromic 1,2-dihetarylethenes containing maleimide-bridged thieno[3,2-b]pyrrole fragments with aliphatic and aromatic substituents at the nitrogen atom were synthesized.

Full text of DOI:10.1023/A:1026069007586

1814
Russian Chemical Bulletin, International Edition, Vol. 52, No. 8, pp. 1814—1816, August, 2003
Photochromic dihetarylethenes
19.* Synthesis of 1,2ꢀdihetarylethenes on the basis
of thieno[3,2ꢀb]pyrroles linked by a maleimide bridge
a
a
a
M. M. Krayushkin,a V. N. Yarovenko, S. L. Semenov, I. V. Zavarzin,
ꢀ
A. Yu. Martynkin,a and B. M. Uzhinovb
aN. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (095) 137 6939. Eꢀmail: mkray@mail.ioc.ac.ru
bDepartment of Chemistry, M. V. Lomonosov Moscow State University,
Leninskie Gory, 119899 Moscow, Russian Federation.
Fax: +7 (095) 932 8846. Eꢀmail: uzhinov@mail.ru
New photochromic 1,2ꢀdihetarylethenes containing maleimideꢀbridged thieno[3,2ꢀb]pyrꢀ
role fragments with aliphatic and aromatic substituents at the nitrogen atom were synthesized.
Key words: photochromes, 1,2ꢀdihetarylethenes, thieno[3,2ꢀb]pyrroles, maleic anhydride,
maleimides.
1,2ꢀDihetarylethenes are considered as promising carꢀ
ethanol for 6—7 h and affords photochromic 1,2ꢀdiꢀ
hetarylethenes 2a—h in good yields (Scheme 1).
riers of threeꢀdimensional optical memory.2,3 A rather
large number of derivatives of this type have now been
obtained; however, the broad range of demands placed on
photochromic substances stimulates the synthesis of new
compounds of this class. A promising route in the design
of these structures is the use of fused heterocycles, beꢀ
cause photochromic products based on heterocycles such
as benzothiophene, indole, and thieno[3,2ꢀb]thiophene
are known to possess high fatigue resistance and thermal
irreversibility.3,4
Scheme 1
Previously,5 we have demonstrated for the first time
that thieno[3,2ꢀb]pyrroles, close analogs of the aboveꢀ
mentioned heterocycles, can be used in the design of
photochromic system 1, which exhibits a high thermal
irreversibility. It is also known that the maleimide fragꢀ
ment is widely used in photochromic 1,2ꢀdihetarylethenes
as a bridge. The transformation of 1,2ꢀdihetarylmaleic
anhydrides into maleimides containing an unsubstituted
nitrogen atom (on treatment with ammonium acetate or
hexamethyldisilazane) or into Nꢀalkylmaleimides (using
aliphatic amines) has been reported; however, no data
concerning the use of aromatic amines in these reactions
are available.6,7
R = Me (a), CH2CH2OH (b), CH2Ph (c), CH2CH=CH2 (d),
CH2C(O)Ph (e), OMe (f), 2ꢀpyridyl (g), Ph (h)
It is worth noting that substituents present at the
maleimide nitrogen atom include hydroxyethyl, allyl, and
phenacyl groups, capable of further transformations. For
example, photochromes 2b,d can be used in the formaꢀ
tion of films or can be grafted to appropriate matrices.
By using Oꢀmethylhydroxylamine, photochrome 2f,
containing a methoxy group at the nitrogen atom of the
maleimide ring, was synthesized for the first time.
This study is an attempt to construct new photochroꢀ
mic compounds containing thieno[3,2ꢀb]pyrrole fragꢀ
ments with Nꢀsubstituted maleimide bridges by the reacꢀ
tion of furandione 1 with a series of aliphatic and aroꢀ
matic amines. This reaction takes place on refluxing in
* For Part 18, see Ref. 1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1719—1721, August, 2003.
1066ꢀ5285/03/5208ꢀ1814 $25.00 © 2003 Plenum Publishing Corporation

Thieno[3,2ꢀb]pyrroles linked by a maleimide bridge Russ.Chem.Bull., Int.Ed., Vol. 52, No. 8, August, 2003
1815
Table 1. Photochemical characteristics of the obtained comꢀ
pounds
row range, 582—590 nm. The only deviation, the reason
for which is not entirely clear, is λ = 548 nm found for
compound 2f, containing the OMe group.
Comꢀ
pound
R
λ
max/nm
τ*/h
The photochromes 2b—h we synthesized are highly
thermally stable (see Table 1), as determined from the
variation of the intensity of the absorption bands correꢀ
sponding to the cyclic forms (B). The data concerning the
thermal stability indicate that products 2b—e,h are therꢀ
mally irreversible over the time periods indicated in
Table 1. The cyclic forms of photochromes 2f,g undergo
only insignificant transformations into the open forms (A)
over a period of 340 h.
A
B
2b
2c
2d
2e
2f
CH2CH2OH
CH2Ph
CH2CH=CH2 294
СH2COPh
OMe
2ꢀPy
293
293
359, 412, 582
358, 414, 584
357, 413, 583
415, 586
414, 548
361, 415, 588
>50
>340
>430
>840
**
293
293
293
294
2g
2h
***
Ph
339, 414, 590 >1200
* Thermal stability in the absence of irradiation.
** Over a period of 340 h, 4% of the cyclic form decomposes.
*** Over a period of 340 h, 3% of the cyclic form decomposes.
Experimental
1
H NMR spectra were recorded on Bruker WMꢀ200
(200 МHz) and Bruker WMꢀ250 (250 МHz) instruments in
DMSOꢀd6 and CDCl3 relative to HMDS. Mass spectra were
run on a Varian MAT CHꢀ6 instrument with direct sample
injection into the ion source; the ionization energy was 70 eV
and the accelerating voltage was 1.75 kV. Melting points were
measured on a Boetius hot stage and were not corrected. The
reaction mixtures were analyzed and the purity of the isolated
products was checked by TLC on Silufol UVꢀ254 plates using an
AcOEt—nꢀC6H14 mixture (1 : 3 v/v) as the eluent.
The samples were irradiated with a DRShꢀ100 mercury lamp
using light filters for separation of mercury spectrum lines
(313 and 546 nm). The absorption spectra were recorded on a
Shimadzu UVꢀ3100 spectrophotometer. The thermal stability of
the cyclic forms was studied at room temperature.
The reaction of the maleic anhydride fragment in
1,2ꢀdihetarylethenes with aromatic amines was also perꢀ
formed for the first time. Photochromic products 2g,h
were isolated in ∼70% yields after refluxing compound 1
in ethanol with aniline or 2ꢀaminopyridine for 6—7 h.
The photochromic properties of the compounds obꢀ
tained were studied in an acetonitrile solution (Table 1); a
typical absorption spectrum of compound 2e is shown in
Fig. 1. The absorption spectra of all the studied subꢀ
stances contain isosbestic points. The fact that the posiꢀ
tions of these points for the forward and back reactions
coincide implies a fully reversible photocyclization and
the absence of side processes. The introduction of differꢀ
ent in kind substituents to the nitrogen atom of the
maleimide bridge does not affect the position of the abꢀ
sorption maxima of the open form (λ = 293—294 nm).
The situation observed for the absorption maxima of the
cyclic form is virtually the same. For photochromes with
aliphatic and aromatic substituents, they occur in a narꢀ
The starting furandione 1 was synthesized by a procedure
described previously.5
Synthesis of maleimides (general procedure). Amine
(0.11 mmol) and TsOH (0.001 g) were added to furandione 1
(0.05 g, 0.1 mmol) in 2—4 mL of 99.5% ethanol and the mixture
was refluxed for 4—8 h (TLC monitoring). The solvent was
evaporated in vacuo and the product was purified by preparative
thin layer chromatography on silica gel and recrystallized
from EtOH.
3,4ꢀBis(5ꢀmethoxycarbonylꢀ2ꢀmethylꢀ4Hꢀthieno[3,2ꢀb]pyrꢀ
rolꢀ3ꢀyl)ꢀ1ꢀmethylꢀ1Hꢀpyrroleꢀ2,5ꢀdione (2a). The yield of 2a
was 0.039 g (76%), m.p. 219—221 °C. MS, m/z: 497 [M]+.
1H NMR (CDCl3), δ: 1.81 (s, 6 H, 2 Me); 3.82 (s, 6 H, 2 MeO);
7.07 (s, 2 H, 2 CHarom); 9.12 (s, 2 H, 2 NH). Found (%):
C, 55.79; H, 3.86; N, 8.60; S, 12.95. C23H19N3O6S2. Calcuꢀ
lated (%): C, 55.52; H, 3.85; N, 8.45; S, 12.89.
1ꢀ(2ꢀHydroxyethyl)ꢀ3,4ꢀbis(5ꢀmethoxycarbonylꢀ2ꢀmethylꢀ
4Hꢀthieno[3,2ꢀb]pyrrolꢀ3ꢀyl)ꢀ1Hꢀpyrroleꢀ2,5ꢀdione (2b). The
yield of 2b was 0.038 g (70%), m.p. 143—145 °C. MS, m/z:
527 [M]+. 1H NMR (DMSOꢀd6), δ: 1.81 (s, 6 H, 2 Me); 3.40 (s,
2 H, NCH2); 3.70 (s, 2 H, CH2OH); 3.82 (s, 6 H, 2 MeO); 7.07
(s, 2 H, 2 CHarom); 11.69 (s, 2 H, 2 NH). Found (%): C, 54.80;
H, 4.03; N, 8.07; S, 12.30. C24H21N3O7S2. Calculated (%):
C, 54.64; H, 4.01; N, 7.96; S, 12.16.
A (rel. units)
293
0.8
0.6
0.4
0.2
415
586
1ꢀBenzylꢀ3,4ꢀbis(5ꢀmethoxycarbonylꢀ2ꢀmethylꢀ4Hꢀ
thieno[3,2ꢀb]pyrrolꢀ3ꢀyl)ꢀ1Hꢀpyrroleꢀ2,5ꢀdione (2c). The yield
of 2c is 0.021 g (35%), m.p. 144—146 °C. MS, m/z: 573 [M]+.
1H NMR (CDCl3), δ: 1.93 (s, 6 H, 2 Me); 3.88 (s, 6 H, MeO);
4.87 (s, 2 H, CH2); 7.06 (s, 2 H, 2 CHarom); 7.30—7.60 (m, 5 H,
0
300
400
500
600
700
λ/nm
Fig. 1. Variation of the absorption spectra of photochrome 2e on
exposure to light with λ = 313 nm.

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Russ.Chem.Bull., Int.Ed., Vol. 52, No. 8, August, 2003
Krayushkin et al.
Ph); 9.18 (s, 2 H, 2 NH). Found (%): C, 60.84; H, 4.05; N, 7.52;
S, 11.40. C29H23N3O6S2. Calculated (%): C, 60.72; H, 4.04;
N, 7.33; S, 11.18.
J = 7.46 Hz); 8.72 (d, 1 H, CHpyridine, J = 4.19 Hz); 9.30 (s, 2 H,
2 NH). Found (%): C, 57.93; H, 3.62; N, 10.15; S, 11.65.
C27H20N4O6S2. Calculated (%): C, 57.85; H, 3.60; N, 9.99;
S, 11.44.
3,4ꢀBis(5ꢀmethoxycarbonylꢀ2ꢀmethylꢀ4Hꢀthieno[3,2ꢀb]pyrꢀ
rolꢀ3ꢀyl)ꢀ1ꢀphenylꢀ1Hꢀpyrroleꢀ2,5ꢀdione (2h). The yield of 2h
was 0.04 g (69%), m.p. 183—185 °C. MS, m/z: 559 [M]+.
1H NMR (DMSOꢀd6), δ: 1.88 (s, 6 H, 2 Me); 3.82 (s, 6 H,
2 MeO); 7.10 (s, 2 H, 2 CHarom); 7.50—7.80 (m, 5 H, Ph); 11.98
(s, 2 H, 2 NH). Found (%): C, 60.25; H, 3.78; N, 7.75; S, 11.62.
C28H21N3O6S2. Calculated (%): C, 60.09; H, 3.78; N, 7.51;
S, 11.46.
1ꢀAllylꢀ3,4ꢀbis(5ꢀmethoxycarbonylꢀ2ꢀmethylꢀ4Hꢀthieꢀ
no[3,2ꢀb]pyrrolꢀ3ꢀyl)ꢀ1Hꢀpyrroleꢀ2,5ꢀdione (2d). The yield of
2d was 0.043 g (80%), m.p. 178—180 °C. MS, m/z: 523 [M]+.
1H NMR (CDCl3), δ: 1.81 (s, 6 H, 2 Me); 3.88 (s, 6 H, 2 MeO);
3.92 (s, 1 H, CH=); 4.33 (d, 2 H, CH2=, J = 5.86 Hz); 5.32 (m,
2 H, CH2); 7.07 (s, 2 H, 2 CHarom); 9.17 (s, 2 H, 2 NH).
Found (%): C, 57.60; H, 4.03; N, 8.07; S, 12.30. C25H21N3O7S2.
Calculated (%): C, 57.35; H, 4.04; N, 8.03; S, 12.25.
3,4ꢀBis(5ꢀmethoxycarbonylꢀ2ꢀmethylꢀ4Hꢀthieno[3,2ꢀb]pyrꢀ
rolꢀ3ꢀyl)ꢀ1ꢀ(2ꢀoxoꢀ2ꢀphenylethyl)ꢀ1Hꢀpyrroleꢀ2,5ꢀdione (2e).
The yield of 2e was 0.036 g (63%), m.p. 141—143 °C. MS, m/z:
References
1
601 [M]+. H NMR (CDCl3), δ: 2.01 (s, 6 H, 2 Me); 3.86 (s,
6 H, 2 MeO); 5.15 (s, 2 H, CH2); 7.07 (s, 2 H, 2 CHarom); 7.55
(t, 2 H, 2 CHarom, J = 7.5 Hz); 7.66 (d, 1 H, CHarom, J =
7.25 Hz); 8.04 (d, 1 H, CHarom, J = 7.52 Hz); 9.17 (s, 2 H,
2 NH). Found (%): C, 59.97; H, 3.85; N, 7.12; S, 10.82.
C30H23N3O7S2. Calculated (%): C, 59.89; H, 3.85; N, 6.98;
S, 10.66.
1ꢀMethoxyꢀ3,4ꢀbis(5ꢀmethoxycarbonylꢀ2ꢀmethylꢀ4Hꢀthieꢀ
no[3,2ꢀb]pyrrolꢀ3ꢀyl)ꢀ1Hꢀpyrroleꢀ2,5ꢀdione (2f). The yield of 2f
was 0.040 g (76%), m.p. 148—150 °C. MS, m/z: 513 [M]+.
1H NMR (CDCl3), δ: 1.97 (s, 6 H, 2 Me); 3.88 (s, 6 H, 2 MeO);
4.15 (s, 3 H, MeON); 7.07 (s, 2 H, 2 CHarom); 9.13 (s, 2 H,
2 NH). Found (%): C, 53.95; H, 3.74; N, 8.32; S, 12.62.
C23H19N3O7S2. Calculated (%): C, 53.79; H, 3.73; N, 8.18;
S, 12.49.
1. M. M. Krayushkin, F. M. Stoyanovich, O. Yu. Zolotarskaya,
V. N. Yarovenko, V. N. Bulgakova, I. V. Zavarzin, and A. Yu.
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3. M. M. Krayushkin, Khim. Geterotsikl. Soedinen., 2001, 19
[Chem. Heterocycl. Compd., 2001, 37 (Engl. Transl.)].
4. Jpn Pat. 06161024; Chem. Abstrs., 1995, 122, 68408.
5. M. M. Krayushkin, V. N. Yarovenko, S. L. Semenov, I. V.
Zavarzin, V. Z. Shirinyan, A. Yu. Martynkin, and B. M.
Uzhinov, Zh. Org. Khim., 2002, 38, 1386 [Russ. J. Org. Chem.,
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6. M. M. Faul, J. Org. Chem., 1998, 63, 1961.
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3,4ꢀBis(5ꢀmethoxycarbonylꢀ2ꢀmethylꢀ4Hꢀthieno[3,2ꢀb]pyrꢀ
rolꢀ3ꢀyl)ꢀ1ꢀpyridinꢀ2ꢀylꢀ1Hꢀpyrroleꢀ2,5ꢀdione (2g). The yield of
2g was 0.039 g (67%), m.p. 171—173 °C. MS, m/z: 560 [M]+.
1H NMR (CDCl3), δ: 1.98 (s, 6 H, 2 Me); 3.86 (s, 6 H, MeO);
7.08 (s, 2 H, 2 CHarom); 7.43 (t, 1 H, CHpyridine, J = 6.07 Hz);
Received January 20, 2003;
in revised form April 29, 2003
7.55 (d, 1 H, CHpyridine, J = 7.92 Hz); 7.96 (t, 1 H, CHpyridine
,