Facile synthesis of photoactive diaryl(hetaryl)cyclopentenes by ionic hydrogenation

Article abstract of DOI:10.1039/c6ra11791k

A facile synthetic approach to photoactive diarylethenes comprising a cyclopentene ring as an ethene bridge was developed based on reduction of 2,3-diaryl(hetaryl)cyclopent-2-en-1-ones through an ionic hydrogenation reaction. The method provides access to

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Facile synthesis of photoactive diaryl(hetaryl)cyclopentenes by
ionic hydrogenation
Andrey G. Lvov,a Ekaterina Yu. Bulich,b Anatoly V. Metelitsa,c Valerii Z. Shiriniana*
Received 00th January 20xx,
Accepted 00th January 20xx
A facile synthetic approach to photoactive diarylethenes comprising a cyclopentene ring as an ethene bridge was
developed based on reduction of 2,3-diaryl(hetaryl)cyclopent-2-en-1-ones through ionic hydrogenation reaction. The
method provides an access to unsymmetrical photoswitchable diarylethenes containing benzene, thiophene, or azoles
(thiazole, oxazole, imidazole) as aromatic moieties in 40-71% yields. Diarylethenes comprising two heterocyclic moieties
show typical photochromic properties, with absorption maxima of the photoinduced form in the blue region (yellow
photochromes).
DOI: 10.1039/x0xx00000x
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Photochromic diarylethenes are promising candidates for the family of diarylethenes in order to develop different types of
development of photoswitchable materials and devices.1 light-controlling materials and devices.11-17 In addition, the
Nowadays, synthetic organic chemistry gives access to a great elaboration of an alternative and effective synthetic protocol is
variety of diarylethenes, which in turn allows the investigation one of the major challenges in modern organic synthesis
of relationships between the structure of diarylethene having a high priority in the development of new technologies
molecules and their photochromic properties. The electronic and smart materials.18-20 However, the synthesis of these
and steric effects of the so-called ethene bridge, the fragment compounds remains a difficult task and has a lot of limitations.
with
a
central double bond, greatly influence the There are two synthetic protocols for the preparation of
photochromic properties, including on the absorption maxima diarylcyclopentenes (Scheme 1). One method is based on the
and quantum yields. Strong electron-withdrawing moieties intramolecular McMurry cyclization of 1,5-diarylpentane-1,5-
(perfluorocyclopentene, maleic anhydride, maleimide, diones (pathway
cyclopentenone, etc.) are commonly used as ethene bridges in involves the
I
in Scheme 1).2,21-24 Another approach
Pd-catalyzed cross-coupling of 1,2-
photochromic diarylethenes, while there is only one truly dibromocyclopentene (pathway II in Scheme 1).4,11,12,25,26
electron-neutral core, cycloalkene (mainly cyclopentene).2-4 These methods are quite suitable for thiophene and
Photochromic diarylethenes of the cyclopentene series have benzothiophene derivatives, including unsymmetric,23 but they
several advantages. First, the cyclopentene ethene bridge are generally limited to azole compounds (oxazole, imidazole,
provides a shift of the absorption maxima of the photoinduced thiazole) because the starting compounds are difficult to
form to the blue region giving rise to yellow developing access and the reaction requires harsh conditions. In addition,
photochromic compounds. It is indispensable to prepare red an alternative synthesis was used for the preparation of
and yellow developing diarylethene derivatives for their diarylcyclopentene derivatives by the reduction of the
application as full-color display and in many other fields.5-10 carbonyl group in diarylcyclopentenones.27 The method
Most of diarylethenes based on perfluourocyclopentenes, includes the following three steps: the reduction of
maleic anhydride, maleimides, cyclopentenone and other diarylcyclopentenones with sodium borohydride to hydroxy
carbo- and heterocyclic derivatives belong to red derivatives followed by tosylation and reduction with sodium
photochromes. Yellow developing photochromes are hydride in the last steps, however it is difficult to evaluate the
practically very few and they basically belong to either inverse experimental opportunities of the method as the synthesis
diarylethenes or cyclopentene derivatives. Second, in the case was carried out only for a single substrate.
of photochromes of the cyclopentene series the spectral and
O
O
McMurry reaction
kinetic properties depend only on the nature and substituents
of aryl moieties, which greatly simplifies the management of
these characteristics. Besides, it is of interest to study this
I
Het
Het
Cross-coupling
Reduction
II
Br
Br
Het
Het
a.N.D. Zelinsky Institute of Organic Chemistry RAS, 47 Leninsky prosp., 119991
Moscow, Russian Federation, e-mail: shir@ioc.ac.ru
O
This work
b.Mendeleev University of Chemical Technology of Russia, Miusskaya Sq., 9,
Moscow, 125047, Russian Federation.
Het
Het
c. Institute of Physical and Organic Chemistry, Southern Federal University, 194/2
Stachka Avenue, Rostov on Don 344090, Russian Federation.
Scheme 1 Recent approaches to the synthesis of photochromic diarylcyclopentenes
J. Name., 2013, 00, 1-3 | 1
Electronic Supplementary Information (ESI) available: experimental procedures
and full spectroscopic data for all new compounds. See DOI: 10.1039/x0xx00000x
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In the last decades photochromic diarylethenes bearing azole ethene bridge (Scheme 2).34 These compounds can be
units28-32 have attracted much attention because of their synthesized from readily available ketoesters
and
potential ability to form hydrogen bond and the possibility of bromoketones based on thiophene, benzothiophene,
its application as an effective tool for the spatiotemporal benzene,34,35 oxazole,36,37 imidazole38 derivatives, as well as
control of switchable biological systems.33 some other heterocyclic compounds.39 Due to the possibility of
1
2
Therefore, the development of an alternative method for the varying the heterocyclic moieties, 2,3-diaryl(hetaryl)cyclopent-
preparation of diary(hetaryl)lcyclopentenes based on azoles, 2-en-1-ones can be considered as suitable synthons for the
primarily unsymmetrical, is of most importance for the design synthesis of diarylcyclopentene derivatives. We have found
of new smart materials for various fields of science, medicine that the ionic hydrogenation (Kursanov reaction)40 in Olah’s
and technology. In this study, we present a novel method for modification41 is a convenient method for carbonyl reduction.
the synthesis of diaryl(hetaryl)cyclopentenes by ionic In this reaction triethylsilane serves as a reducing agent in the
hydrogenation of appropriate cyclopentenone derivatives.
Earlier, we have proposed a new type of photochromic 2,3-di(het)arylcyclopent-2-en-1-ones
diarylethenes based on the cyclopentenone core as an hydrogenation reaction (Scheme 2, Table 1).
presence of trifluoromethanesulfonic acid. A wide range of
3
were tested in the ionic
3
Scheme 2 Synthetic protocol for the preparation of diarylcyclopentenes 4
Table 1 Structures and spectral properties of diarylethenes 3 and 4
Diarylethene 3
Diarylethene 4
№
Ar1
Ar2
Yield of 3a Yield of 4
λmax(A)b
λmax(B)c
λmax(A)b
λmax(B)c
d
d
N
3a/4a
35%
52%
40%
71%
64%
65%
300
-
294
-
Me
Me
Ph
O
e
-
e
-
N
3b/4b
3c/4c
362
298
319
290
N
N
523
452
Me
Me
Me
Me
Me
Me
Me
Me
Me
Ph
S
S
S
S
O
N
f
f
Me
O
3d/4d
3e/4e
3f/4f
15%
32%
21%
61%
60%
50%
251, 385
343
-
250, 385
325
-
S
N
501
555
420
460
Me
Me
Ph
Ph
N
N
329
293
Me
N
3g/4g
35%
40%
327
558
296
481
Me
Ph
S
N
Me
Me
S
Ph
N
N
3h/4h
3i/4i
20%
34%
60%
33%
57%
48%
0%
346
359
540
565
284
304
424
500
Me
Me
Me
Ph
Me
Me
Me
Me
Me
Me
Me
Me
S
S
S
N
N
3j/4j
Me
Ph
S
N
N
3k/4k
0%
O
O
aThe yields of 3 are given for two steps; b The absorption maxima of the open-ring isomer, nm; cThe absorption maxima of the closed-ring isomer, nm; dThe irreversible
photorearrangement affords a naphthalene derivative [ref 42]; eStable under irradiation; fPhotochromic properties are poorly manifested.
2 | J. Name., 2012, 00, 1-3
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The nature of the heterocycle attached to the central double of this isomer could be explained by [1,3]-H shift of
bond strongly affects the ionic hydrogenation process. The diarylethene 4a
.
reduction of ketones, including benzene or 2,5-
dimethylthiophene at position 2 of the cyclopentenone and
azoles at position 3 (compounds 3a-i), proceeded smoothly in
40-71% yields. The ionic hydrogenation of diarylethenes
bearing oxazolyl and thiazolyl moieties (compounds 3a-e) was
accomplished at room temperature, whereas the reduction of
Scheme 4 The ionic hydrogenation of the cyclopentenone 3a
.
imidazole (3f,g), imidazo[2,1-
b]thiazole (3h) and imidazo[1,2-
a
]pyridine (3i) derivatives requires prolonged heating under
Depending on the nature of aryl moieties, diarylethenes
showed different behavior under UV irradiation. Diarylethene
4a based on oxazole and benzene rings underwent
photorearrangement to a naphthalene derivative.42 Compound
4b (bearing benzene and imidazo[1,2- ]pyridine as the
4
reflux. This can be explained by strong basicity of the imidazole
rings, resulting in the protonation of the starting diarylethenes,
thus decelerating the ionic hydrogenation process. Meanwhile,
a
we
failed
to
reduce
bis-(2,5-dimethylthien-3-
b
yl)cyclopentenone 3j. Even after prolonged heating under
reflux (for more 12 hrs), no conversion was observed and the
starting compound was completely returned (for details see
Supplementary data). The increase of the reaction
temperature (refluxing in dichloroethane) also does not lead to
substituents), as well as parent ketone 3b, showed unexpected
stability under the action of light. On the contrary, compounds
4c,e-i comprising two heterocycles as aryl moieties (excluding
anthracene derivative 4d
, which has no photochromic
properties because of strong fluorescence) exhibited typical
photochromic properties (Scheme 5).
the desired results, there is observed only
a gradual
degradation of the starting cyclopentenone. The proposed
mechanism of this transformation involves two-fold stepwise
protonation-hydride transfer reaction (Scheme 3). Apparently,
the protonation of 3j produces the more stabilized carbocation
intermediate 5, which completely inhibits the hydride transfer
and the further reduction of carbonyl groups.41 Another
limitation of this reaction is that it is difficult to reduce bis-
oxazolyl derivative 3k
. In this case, the reaction was
Scheme 5 Photocyclization of diarylcyclopentenes
accompanied by a number of side processes and the target
product was not isolated.
Figure 1 presents the absorption spectra of a solution of 4f
before and after UV irradiation. Initial isomer
A has a
O
HO
HO
H+
H-
+
maximum at 293 nm; photoisomer B, at 460 nm. A reverse
Ar1
Ar2
Ar1
Ar2
Ar1
Ar2
H-
photoreaction occurs under the action of visible light. As can
be seen in Table 1, the reduction of the carbonyl group in
3
5
6
H+
-H2O
diarylethenes 3 resulted in a hypsochromic shift of the maxima
+
of both the initial and photoinduced forms. It should be noted
that photochromic diarylethenes 3c,e-i characterized by
absorption maxima in the blue region of the visible spectrum,
in other words, they are yellow photochromes. Earlier, the lack
of examples of such photochromes has been noted,5,6 and
solutions to this issue have been proposed in a number of
studies.7-10 As can be seen in Table 1, the introduction of
various azole groups into cyclopentene-based diarylethenes
Ar1
Ar2
Ar1
Ar2
4
7
Scheme
3 Proposed mechanistic pathway of the ionic hydrogenation of the
diarylcyclopentenones
As can be seen in Table 1, the reduction of
diarylcyclopentenones 3a-i proceeds in moderate yields (48-
71%). It should be noted that in all the cases except
diarylethene 3a, the reaction gives no by-products and only a
slight resinification is observed. An interesting result was
obtained in the reduction of 3a. Thus, the reaction affords by-
gives rise to photochromes with absorption maxima of form
B
in the range from 420 to 500 nm. We supposed that a new
synthetic strategy for the preparation of azole-containing
diaryl(hetaryl)cyclopentenes opens up new opportunities to
access the photochromic compounds with specified spectral
properties including absorption maxima.
product
8
in 10% yields along with the target
diarylcyclopentene 4a in 71% yield (Scheme 4). The formation
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15 D. Wilson and N. R. Branda, Angew. Chem. Int. Ed., 2012, 51
5431.
,
16 A. R. Tuktarov, A. A. Khuzin, A. R. Akhmetov, V. A.
Barachevsky, O. V. Venidiktova and U. M. Dzhemilev,
Tetrahedron Lett., 2015, 56, 7154.
17 O. Babii, S. Afonin, L. V. Garmanchuk, V. V. Nikulina, T. V.
Nikolaienko, O. V. Storozhuk, D. V. Shelest, O. I. Dasyukevich,
L. I. Ostapchenko, V. Iurchenko, S. Zozulya, A. S. Ulrich and I.
V. Komarov, Angew. Chem., Int. Ed., 2016, 55, 5493.
18 Carruthers, W.; Coldham, I. “Modern Methods of Organic
Synthesis” 4th ed.; Cambridge, UK, 2004.
19 Ananikov, V. P.; Khokhlova, E. A.; Egorov, M. P.; Sakharov, A.
M.; Zlotin, S. G.; Kucherov, A. V.; Kustov, L. M.; Gening, M. L.;
Nifantiev, N. E. Mendeleev Commun., 2015, 25, 75-82.
20 For more detailed reviews on the modern organic synthesis
see also original review articles in Chem. Rev. 2015, Vol. 115,
issue 17, pp. 8945-9654.
Figure 1. Changes of an absorption spectrum of compound 4f under irradiation with UV
light (313 nm, 6W lamp) in acetonitrile (c ≈ 10-5 M).
21 M. M. Krayushkin, M. A. Kalik and V. A. Migulin, Russ. Chem.
Rev., 2009, 78, 329.
22 Z.-N. Huang, B.-A. Xu, S. Jin and M.-G. Fan, Synthesis, 1998,
1092.
23 V. A. Migulin, M. M. Krayushkin, V. A. Barachevsky, O. I.
Kobeleva, T. M. Valova and K. A. Lyssenko, J. Org. Chem.,
2012, 77, 332.
24 V. A. Migulin, M. M. Krayushkin, V. A. Barachevsky, O. I.
Kobeleva, V. V. Novikov and K. A. Lyssenko, Tetrahedron,
2015, 71, 584.
25 M. Herder, M. Utecht, N. Manicke, L. Grubert, M. Patzel, P.
Saalfrank and S. Hecht, Chem. Sci., 2013, 4, 1028.
Conclusions
In summary, we have proposed a new synthetic approach for
the preparation of photoactive diaryl(hetaryl)cyclopentenes.
The method allows the synthesis of unsymmetrical products
bearing thiophene, benzene or various azoles as aryl moieties
starting from appropriate available ketones in 40-71% yields.
26 T. Yamaguchi, M. Hosaka, K. Shinohara, T. Ozeki, M. Fukuda,
S. Takami, Y. Ishibashi, T. Asahi and M. Morimoto, J.
Photochem. Photobiol. A, 2014, 285, 44.
27 N.-H. Nam, Y. Kim, Y.-J. You, D.-H. Hong, H.-M. Kim and B.-Z.
Ahn, Bioorg. Med. Chem. Lett., 2002, 12, 1955.
28 Irie, M., Yokoyama, Y., Seki, T., Eds. New Frontiers in
Acknowledgements
Authors thank the Russian Foundation for Basic Research
(RFBR grant 15-03-05546) for financial support of this study.
This work was also partly financially supported by the Russian
Science Foundation (RSF grant 14-50-00126) in regard with the
characterization of the compounds obtained. The authors
thank Professor Leonid I. Belen’kii for helpful comments.
Photochromism Springer: Tokyo, 2013
.
29 K. Morinaka, T. Ubukata and Y. Yokoyama, Org. Lett., 2009,
11, 3890.
30 S. Fukumoto, T. Nakashima and T. Kawai, Angew. Chem., Int.
Ed., 2011, 50, 1565.
31 H. Ogawa, K. Takagi, T. Ubukata, A. Okamoto, N. Yonezawa,
S. Delbaere and Y. Yokoyama, Chem. Commun., 2012, 48
11838.
32 R. Li, T. Nakashima, O. Galangau, S. Iijima, R. Kanazawa and
T. Kawai, Chem. Asian J., 2015, 10, 1725.
33 W. Szymanski, J. M. Beierle, H. A. V. Kistemaker, W.A.
Velema and B. L. Feringa, Chem. Rev., 2013, 113, 6114.
34 V. Z. Shirinian, A. A. Shimkin, D. V. Lonshakov, A. G. Lvov and
M. M. Krayushkin, J. Photochem. Photobiol., A, 2012, 233, 1.
35 V. Z. Shirinian, D. V. Lonshakov, A. G. Lvov, A. M. Kavun, A. V.
Yadykov and M. M. Krayushkin, Dyes Pigm., 2016, 124, 258.
36 V. Z. Shirinian, A. G. Lvov, M. M. Krayushkin, E. D. Lubuzh and
B. V. Nabatov, J. Org. Chem., 2014, 79, 3440.
37 A. G. Lvov, V. Z. Shirinian, A. M. Kavun and M. M. Krayushkin,
Mendeleev Commun., 2014, 24, 277.
38 V. Z. Shirinian, A. G. Lvov, E. Yu. Bulich, A. V. Zakharov and M.
M. Krayushkin, Tetrahedron Lett., 2015, 56, 5477.
39 A. G. Lvov, V. Z. Shirinian, A. V. Zakharov, M. M. Krayushkin,
,
Notes and references
1
M. Irie, T. Fukaminato, K. Matsuda, and S. Kobatake, Chem.
Rev., 2014, 114, 12174.
2
L. N. Lucas, J. J. D. de Jong, J. H. van Esch, R. M. Kellogg and
B. L. Feringa, Eur. J. Org. Chem., 2003, 155.
G. Szalóki and J.-L. Pozzo, Chem. Eur. J., 2013, 19, 11124.
M. Herder, B. Schmidt, L. Grubert, M. Pätzel, J. Schwarz and
S. Hecht, J. Am. Chem. Soc., 2015, 137, 2738.
H. Dürr, H. Bouas-Laurent, Eds. Photochromism: Molecules
and Systems; Elsevier: Amsterdam, 2003.
3
4
5
6
7
K. Uchida and M. Irie, Chem. Lett., 1995, 969.
Q. Luo, X. Li, S. Jing, W.-H. Zhu and H. Tian, Chem. Lett., 2003,
32, 1116.
8
9
S. Takami and M. Irie, Tetrahedron, 2004, 60, 6155.
C. Zheng, S. Pu, G. Liu and B. Chen., Tetrahedron Lett., 2013,
54, 7024.
10 S. Takami, A. Shimizu, K. Shimizu, R. Miyoshi, T. Yamaguchi
and M. Irie, Bull. Chem. Soc. Jpn., 2013, 86, 1059.
11 M. Singer and A. Jäschke, J. Am. Chem. Soc., 2010, 132, 8372.
12 H. Cahova and A. Jäschke, Angew. Chem. Int. Ed., 2013, 52
3186.
13 E. Orgiu, N. Crivillers, M. Herder, L. Grubert, M. Patzel, J.
Frisch, E. Pavlica, D. T. Duong, G. Bratina, A. Salleo, N. Koch,
S. Hecht and P. Samori, Nature Chem., 2012, 675.
14 D. Vomasta, C. Högner, N. R. Branda and B. König, Angew.
Chem. Int. Ed., 2008, 47, 7644.
V. V. Kachala and I. V. Zavarzin, J. Org. Chem., 2015, 80
11491.
,
40 D. N. Kursanov, Z. N. Parnes and N. M. Loim, Synthesis, 1974,
633.
41 G. A. Olah, M. Arvanaghi and L. Ohannesian, Synthesis, 1986,
770.
42 A. G. Lvov, V. Z. Shirinian, V. V Kachala, A. M. Kavun, I. V.
Zavarzin and M. M. Krayushkin, Org. Lett., 2014, 16, 4532.
,
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