PEG-400 assisted Kr?hnke synthesis of 2-(2-hydroxyphenyl)-4-arylpyridines annulated by C5-C6 cycles with substituted benzylidene group

Article abstract of DOI:10.1080/00397911.2019.1706182

A simple and efficient method has been developed for the synthesis 2-(2-hydroxyphenyl)-4-arylpyridines annulated by C₅-C₆ cycles with substituted benzylidene group is achieved by multi-component Kr?hnke-type reaction with moderate to

Full text of DOI:10.1080/00397911.2019.1706182

Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic
Chemistry
ISSN: 0039-7911 (Print) 1532-2432 (Online) Journal homepage: https://www.tandfonline.com/loi/lsyc20
PEG-400 assisted Kröhnke synthesis of 2-(2-
hydroxyphenyl)-4-arylpyridines annulated by C5-C6
cycles with substituted benzylidene group
Sergey Batalin, Margarita Golikova, Alexandra Khrustaleva & Nina
Pchelintseva
To cite this article: Sergey Batalin, Margarita Golikova, Alexandra Khrustaleva & Nina
Pchelintseva (2020): PEG-400 assisted Kröhnke synthesis of 2-(2-hydroxyphenyl)-4-arylpyridines
annulated by C5-C6 cycles with substituted benzylidene group, Synthetic Communications, DOI:
10.1080/00397911.2019.1706182
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SYNTHETIC COMMUNICATIONSV
https://doi.org/10.1080/00397911.2019.1706182
€
PEG-400 assisted Krohnke synthesis of 2-(2-hydroxyphenyl)-
4-arylpyridines annulated by C5-C6 cycles with substituted
benzylidene group
Sergey Batalin , Margarita Golikova, Alexandra Khrustaleva, and
Nina Pchelintseva
Department of Organic and Bioorganic Chemistry, Institute of Chemistry, National Research State
University, Saratov, Russia
ABSTRACT
ARTICLE HISTORY
Received 26 October 2019
A simple and efficient method has been developed for the synthesis
2-(2-hydroxyphenyl)-4-arylpyridines annulated by C5-C6 cycles with
substituted benzylidene group is achieved by multi-component
Krohnke-type reaction with moderate to good yields in PEG-400. The
classical version was considered using cross-conjugated dienones as
substrates by counter synthesis.
KEYWORDS
€
Cross-conjugated dienones;
2-(2-hydroxyphenyl)pyri-
€
dines; Krohnke reaction;
PEG-400
GRAPHICAL ABSTRACT
Introduction
In recent years, the development of highly efficient, selective, green, safe, atomic and
stepwise-economic strategies for the synthesis of target compounds became one of
the most prominent areas of organic chemistry. Special attention is paid to multi-
component reactions (MCR) as they allow simplifying product separation, reducing
reaction time and usually result in higher overall yield of final product compared to
step-by-step synthesis.[1] It should be also noted that polyethylene glycol 400 has
become a common solvent used for various organic reactions as it is inexpensive, ther-
mally stable and easy to use. It also has low toxicity, thus making it preferable for
“green” chemistry applications.[2] Thus PEG-400 and derivatives of PEG are an effective
CONTACT Sergey Batalin
batalinsd@bk.ru
Department of Organic and Bioorganic Chemistry, Institute of
Chemistry, National Research State University, Saratov 410012, Russia.
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/lsyc.
Supplemental data for this article can be accessed on the publisher’s website.
ß 2020 Taylor & Francis Group, LLC

2
S. BATALIN ET AL.
Scheme 1. Microwave assisted synthesis of annulated pyridines.
alternative medium for various multi-component transformations and can be used for
such reactions as Biginelli reaction,[3] 1,3-dipolar cycloaddition,[4] Hantzch synthesis[5]
and other multi-component reactions.[6]
The pyridine heterocyclic core is widespread in various natural products, pharmaceut-
icals,[7] and supramolecular assemblies with p–p staking and directional H-bonding.[8]
€
One method used for constructing this heterocycle is a two-step Krohnke synthesis via
reaction of pyridinium salts with a,b-unsaturated ketones in the presence of a mixture
of ammonium acetate and acetic acid or other solvent.[9] Recently special attention has
€
been paid to Krohnke multi-component reaction where a,b-unsaturated intermediate is
not isolated from the reaction medium, which was confirmed for one-pot synthesis of
2,4,6-triarylpyridines,[10,11] substituted 5,6-dihydrobenzo[h]quinolines,[11] 5,7-dihydro-
1,6-naphtyridines,[12] and annulated by ‘5-‘ cycles pyridines[11–13] were obtained
8
assisted by microwave irradiation (Scheme 1).
Non-symmetric 2-(2-hydroxyaryl)pyridines and their derivatives have some interest-
ing properties, namely, the ability to form coordination compounds with transition met-
als,[14] a wide spectrum of biological activity[15] and capability of engaging in the
excited state intramolecular proton transfer (ESIPT).[16] These systems are usually syn-
[15,17]
€
thesized via the Krohnke method under classical conditions.
To the best of our
knowledge, PEG-400 has not yet been used for this chemical transformation in the clas-
sical and multi-component versions.
Thus, we would like to report on the application of PEG-400 in multi-component
€
Krohnke-type reaction between aromatic aldehydes, N-(2-hydroxyphenacyl) pyridinium
iodide, C5-C6 cycloalkanones and ammonium acetate, and counter synthesis using a
cross-conjugated dienones from cyclopentanone and cyclohexanone as substrates by
classical version in PEG-400.

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SYNTHETIC COMMUNICATIONSV
3
Table 1. Optimization of reaction conditions.
Entry
1
Substrate
1a
3a (eq.)
Solvent
PEG-400b
Time (min)
15
Yielda %
1.2
4a 40
5a 19
4a 59
4a 67
4a 76
4a 51
4a 56
4a 48
4g 51
4g 58
4g 63
4g 71
4g 44
4g 52
4g 47
2
3
4
5
6
7
8
9
10
11
12
13
14
1a
1a
1a
1a
1a
1a
1b
1b
1b
1b
1b
1b
1b
1.3
1.4
1.5
1.5
1.5
1.5
1.2
1.3
1.4
1.5
1.5
1.5
1.5
PEG-400b
PEG-400b
PEG-400b
CH3CNc
AcOHc
10
8
8
25
25
40
16
10
10
10
30
30
45
EtOHc
PEG-400b
PEG-400b
PEG-400b
PEG-400b
CH3CNc
AcOHc
EtOHc
Reaction conditions: cycloalkanone 1 (1 mmol), benzaldehyde 2a (2 mmol, 2 eq.), N-(2-hydroxyphenacyl) pyridinium iod-
ide 3, ammonium acetate (3 g) aYields of isolated products 4a and 4g after recrystallization from EtOH-CHCl3 mixture
b
c
(with 3:1 ratio). The reaction was performed at 80 ꢀC. Reflux temperature.
Results and discussion
It’s generally known that cross-conjugated dienones are formed as a result of condensa-
tion of aldehydes and cycloalkanones at a 2:1 ratio in the presence of a basic[18] or
acidic[19] catalyst, and there are studies reporting that aldol condensation occurs in
PEG-400 in the presence of potassium carbonate.[20] We hypothesized that cross-
conjugated dienones can serve as the intermediate in the one-pot reaction between
C5-C6-cycloalkanones, aromatic aldehydes and N-(2-hydroxyphenacyl) pyridium iodide
that would result in producing pyridine annulated by C5-C6 cycles with an additional 7-
or 8-substituted benzylidene group.
First, we studied the optimal synthesis conditions for the reaction between C5-C6
cycloalkanones (1a,b), benzaldehyde (2a) and pyridinium salt (3). The impact of various
reaction conditions on the reaction outcome, including amount of pyridinium salt, time
of reaction, and solvents are summarized in Table 1. The reaction proceeded with low
yield in PEG-400 using 1.2 eq. of pyridinium salt (entries 1, 8) with the formation of
cross-conjugated dienone (5a, entry 1) as by-product. Using a larger amount of N-(2-
hydroxyphenacyl) pyridinium iodide 3 in the reaction increased on the yield of the

4
S. BATALIN ET AL.
€
Scheme 2. Gram-scale multi-component Krohnke reaction in PEG-400.
product and reduces reaction time (entries 2–4, 9–11). We have found that the optimal
reagent ratio (1–2a–3) is 1:2:1.5 (entries 4, 11) and temperature 80 ꢀC. A further
increase in the amount of pyridinium salt did not lead to an increase in yield. When
carrying out the synthesis in PEG-400, the reaction proceeded smoothly with good
yields, while for other solvents the transformation takes much more time and the final
product yields are smaller (entries 5–7, 12–14). The reaction was monitored via TLC
with the mixture of hexane-chloroform-ethyl acetate at 3:1:1 ratio used as an eluent. At
the end of the reaction, water is added to the reaction mixture; the product is filtered
off and recrystallized from ethanol-chloroform mixture (with 3:1 ratio).
€
For the quantitative generalization of multicomponent Krohnke-type synthesis, the
above optimized reaction conditions were applied for the reaction between 5 mmol
cycloalkanone 1, 10 mmol benzaldehyde 2a, and 7,5-mmol N-(2-hydroxyphenacyl) pyri-
dinium iodide 3. Reaction finished after 15 min for cyclopentanone 1a and 20 min for
cyclohexanone 1b with good yield (4a, 73%; 4g 66%) (Scheme 2).
After optimization, a series of annulated 2-(2-hydroxyphenyl)pyridines by C5-C6
cycles (4a–k) was synthesized with moderate to good yields with reaction time 8 and
50 min. It should be noted that during the reaction in PEG-400, aromatic aldehydes
containing electron-donating groups, formed annulated 2-(2-hydroxyphenyl) pyridines
with good yield. When the same aromatic aldehyde was used as a substrate, the yields
of the products for cyclopentanone were higher and the reaction time was shorter than
compared to cyclohexanone (Table 2). Isolated products by reactions between the pyri-
dinium salt 3, cyclopentanone 1a and 4-N,N-dimethylaminobenzaldehyde 2g (reaction
time 30 min) and between cyclohexanone 1b and 4-chlorobenzaldehyde 2b (reaction
time 10 min) either were not characterized due to their low solubility in organic sol-
vents. The same is true for the reaction between pyridinium salt, cycloalkanones, 4- and
3-nitro substituted benzaldehydes.
Many works[21] with various C-nucleophiles and N-nucleophiles have been presented
for cross-conjugated dienones, but, as far as we know, the use of these substrates in the
€
Krohnke reaction has never been described. We performed a counter synthesis of annu-
lated pyridines from cross-conjugated dienones (5a–f, 6a–e) (Table 3). When using this
synthetic route, the reaction time increased, the yield of the product decreased, and it
was necessary to use a larger amount of pyridinium salt and ammonium acetate, a

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Table 2. One-pot synthesis of annulated pyridines.
Yielda
%
Entry
Substrate
Product
R
Time (min)
1
2
3
4
5
6
7
8
9
1a 1 2a
1a 1 2b
1a 1 2c
1a 1 2d
1a 1 2e
1a 1 2f
1b 1 2a
1b 1 2c
1b 1 2d
1b 1 2f
4a
4b
4c
4d
4e
4f
4g
4h
4i
Ph
4-Cl-C6H4
4-MeO-C6H4
3,4-(MeO)2-C6H3
3,4,5-(MeO)3-C6H2
4-OH-3-MeO-C6H3
Ph
4-MeO-C6H4
3,4-(MeO)2-C6H3
8
10
12
18
25
30
10
15
25
50
76
69
68
71
64
61
71
59
66
57
10
4j
4-OH-3-MeO-C6H4
Reaction conditions: cycloalkanone 1 (1 mmol), substituted benzaldehyde 2 (2 mmol), N-(2-hydroxyphenacyl) pyridinium
iodide 3 (1,5 mmol), ammonium acetate (3g) in 1 ml PEG-400 at 80 ꢀC. aIsolated yield after recrystallization from
EtOH-CHCl3 mixture (with 3:1 ratio).
Table 3. Counter synthesis of annulated pyridines.
Yielda
Entry
Substrate þ 3 (eq.)
Product
R
Time (min)
%
1
2
3
4
5
6
7
8
9
5a, 2.5
5b, 2.5
5c, 3.0
5d, 3.0
5e, 3.5
5f, 3.5
6a, 2.0
6b, 2.5
6c, 2.5
6d, 3.0
4a
4b
4c
4d
4e
4f
4g
4h
4i
Ph
4-Cl-C6H4
40
45
90
120
160
180
30
45
70
120
46
51
41
34
30
29
54
47
42
43
4-MeO-C6H4
3,4-(MeO)2-C6H3
3,4,5-(MeO)3-C6H2
4-OH-3-MeO-C6H3
Ph
4-MeO-C6H4
3,4-(MeO)2-C6H3
4-OH-3-MeO-C6H4
10
4j
Reaction conditions: cross-conjugated dienone 5 or 6 (1 mmol), N-(2-hydroxyphenacyl) pyridinium iodide 3, ammonium
a
acetate (5g) in 3 ml PEG-400 at 100 ꢀC. Isolated yield after recrystallization from EtOH-CHCl3 mixture (with 3:1 ratio).

6
S. BATALIN ET AL.
Scheme 3. Enol-imino keto-amino tautomerism.
larger volume of PEG-400 and higher reaction temperature. Since cross-conjugated
dienones had an E configuration, the synthesized annulated pyridines also had an E
configuration. Using this path led to the same products as in the multi-component ver-
€
sion. This means that the E-isomer also formed in the one-pot Krohnke type reaction.
The composition of the synthesized compounds was established on the basis of elem-
1
ental analysis data, the structures were further characterized by IR, H and 13C NMR
1
spectroscopy. As the solubility of compound 4e is very low, only its H NMR spectrum
1
was obtained. The characteristic H chemical shift of the phenol proton of products 4
indicates the intramolecular hydrogen bond. This proton resonates as a single peak
because of the difficulty of exchanging a phenolic proton with a deuterated solvent.[23]
In addition, the value of the chemical shift of this proton is influenced by the substitu-
ents in the aromatic ring of the benzylidene group and the aryl group in position 4 of
the pyridine ring. In the 13C NMR spectrum of products 4b, 4c, 4h a carbonyl carbon
signal is detected in solution, but carbonyl absorption was absent in the IR spectra in
the KBr matrix. For these compounds, the signal is detected at 176.55–176.32 ppm in
CDCl3, also in work[22] carbonyl carbon resonated at 174.8 and 171.1 ppm in CDCl3 for
gossypol imine derivatives. These signals may serve as indicators of enol-imino keto-
amine tautomerism of these compounds and the existence of tautomers 7a–c (Scheme
3) in solution. For compounds 4c and 4h, UV-VIS spectra were recorded in acetonitrile
and it were recorded absorption of the carbonyl group with a maximum at 403–430 nm
(4h) and 440–480 nm (4c) region, which is consistent with the paper on the tautomer-
ism of 2-(2-hydroxyaryl)azines.[23]
In the published work[11] on annulated pyridines it was not reported which isomer
was isolated. Some cyclopenta[b]pyridines in the 13C NMR spectrum showed 4 signals
in the region 29.4–27.3, which may be evidence of the presence Z and E isomers. Based
on these data and our results, we propose reaction mechanisms for multicomponent
version, which are depicted in Scheme 4. First possible way is based on cross-conjugated
intermediate. Cycloalkanone 1 and aromatic aldehyde 2 undergo aldol condensation to
form E-cross-conjugated dienone 5, 6, assisted by ammonium acetate.[24] Pyridinium
salt 3 enolizes to form enol A, catalyzed by acetic acid, followed Michael reaction with
cross-conjugated dienone to form 1,5-diketone B. Pyridinium cation is then eliminated
to form unsaturated 1,5-diketone C. Nucleophilic addition ammonia to diketone C fol-
lowed dehydration via D generates enamine E. Enamine cyclizes with the carbonyl to
generate hydroxy-intermediate F. Dehydration of intermediate F generates the target

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SYNTHETIC COMMUNICATIONSV
7
Scheme 4. Proposed mechanisms of multi-component reaction.
product 4. In the second proposed way, cycloalkanone 1 and aromatic aldehyde 2
undergo aldol condensation to form monoenone G, which then reacts with enol A by
Michael reaction to form diketone H. Pyridinium cation is then eliminated to form
unsaturated 1,5-diketone I. Nucleophilic addition ammonia to diketone I followed dehy-
dration via J generates enamine K, which cyclizes with the carbonyl to generate
hydroxy-intermediate L. Dehydration of intermediate L generates the annulated

8
S. BATALIN ET AL.
pyridines M. Ammonium acetate and intramolecular hydrogen bond in annulated pyri-
dine M promote aldol reaction with the aromatic aldehyde 2 to form aldol N, which
dehydrated to form product 4. Intramolecular hydrogen bond in aldol N between the
phenolic proton and the nitrogen atom of the pyridine ring sterically blocks the dehy-
dration and formation of the Z-isomer O and therefore only E-isomers are formed.
When using cross-conjugated dienones 5, 6, the possible mechanism should
be considered along the first way. Comparing the results of the classical and multi-com-
€
ponent versions of the Krohnke reaction for the synthesis of annulated 2-(2-hydroxy-
phenyl)pyridines 4 and based on published data, we believe that the multi-component
version of this transformation proceeds through the second proposed pathway.
€
In conclusion, we have developed new conditions for Krohnke reaction for multi-
component and classical version in PEG-400 between readily available cycloalkanones,
aromatic aldehydes or the corresponding cross-conjugated dienones and N-(2-hydroxy-
phenacyl)pyridinium iodide in the presence of ammonium acetate resulting in a fast
and efficient synthesis of the previously unknown 2-(2-hydroxyphenyl)-4-arylpyridines
annulated by C5-C6 cycles and containing a substituted benzylidene group. According
to the 13C NMR and UV/VIS data, the existence of two tautomeric forms of some com-
pounds was shown. The resulting compounds can be considered as potential N-, O-
bidentate ligands or ESIPT fluorophores.
Experimental section
€
Method A. Multi-component version of Krohnke reaction for products 4; gen-
eral procedure
A mixture of cycloalkanone 1 (1 mmol, 1 eq.), aromatic aldehyde 2 (2 mmol, 2 eq.),
N-(2-hydroxyphenacyl) pyridinium iodide 3 (1.5 mmol, 1.5 eq.) ammonium acetate (3g)
and 1 ml of PEG-400 was stirred at 80 ꢀC for same time. The reaction was monitored
by thin-layer chromatography. After the reaction is finished, ice cold water was added
to the reaction mixture (50 ml) and stirred for 15 min. The resulting solid product 4
was filtered, rinsed with ice cold water (50 ml) and recrystallized from EtOH-CHCl3
mixture (at 3:1 ratio).
€
Method B. Classical version of Krohnke reaction for products 4; general procedure
A mixture of cross-conjugated dienone 5 or 6 (1 mmol, 1 eq.), N-(2-hydroxyphenacyl)
pyridinium iodide 3 (2.0–3.5 mmol, 2–3.5 eq.) ammonium acetate (5g) and 3 ml of
PEG-400 was stirred at 100 ꢀC for same time. The reaction was monitored by thin-layer
chromatography. After the reaction is finished, ice cold water was added to the reaction
mixture (50 ml) and stirred for 15 min. The resulting solid product 4 was filtered,
rinsed with ice cold water (50 ml) and recrystallized from EtOH-CHCl3 mixture (at
3:1 ratio).
1
Full experimental details including all information, H and 13C NMR spectra, elemen-
tal analysis and IR spectra data have been provided in supporting information as a sep-
arate file.

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SYNTHETIC COMMUNICATIONSV
9
Disclosure statement
No potential conflict of interest was reported by the authors.
ORCID
Sergey Batalin
Nina Pchelintseva
http://orcid.org/0000-0001-6771-230X
http://orcid.org/0000-0002-5830-9807
References
ꢀ
ꢀ
[1] (a) Ibarra, I. A.; Islas-Jacome, A.; Gonzalez-Zamora, E. Org. Biomol. Chem. 2018, 16,
1402–1418. DOI: 10.1039/C7OB02305G. (b) Haji, M. Beilstein J. Org. Chem. 2016, 12,
1269–1301. DOI: 10.3762/bjoc.12.121. (c) Volla, C. M. R.; Atodiresei, I.; Rueping, M.
Chem. Rev. 2014, 114, 2390–2431. DOI: 10.1021/cr400215u.
[2] Chen, J.; Spear, S. K.; Huddleston, J. G.; Rogers, R. D. Green Chem. 2005, 7, 64–82. DOI:
10.1039/b413546f.
[3] (a) Jain, S. L.; Singhal, S.; Sain, B. Green Chem. 2007, 9, 740–741. DOI: 10.1039/b702311a.
(b) Wang, X.; Quan, Z.; Wang, F.; Wang, M.; Zhang, Z.; Li, Z. Synth. Commun. 2006, 36,
451–456. DOI: 10.1080/00397910500383519.
[4] (a) Rajeswari, M.; Sindhu, J.; Singh, H.; Khurana, J. M. RSC Adv. 2015, 5, 39686–39691.
DOI: 10.1039/C5RA03505H. (b) Sindhu, J.; Singh, H.; Khurana, J. M. Mol. Divers. 2014,
18, 345–355. DOI: 10.1007/s11030-014-9505-y.
[5] Wang, X.; Gong, H.; Quan, Z.; Li, L.; Ye, H. Synth. Commun. 2011, 41, 3251–3258. DOI:
10.1080/00397911.2010.517888.
[6] (a) Ahad, A.; Maqdoom, F. Chem. Sci. Trans. 2016, 5, 202–206. (b) Nagaraju, A.; Ramulu,
B. J.; Shukla, G.; Srivastava, A.; Verma, G. K.; Raghuvanshi, K.; Singh, M. S. Green Chem.
2015, 17, 950–958. DOI: 10.1039/C4GC01431F. (c) Shitole, N. V.; Shelke, K. F.; Sadaphal,
S. A.; Shingate, B. B.; Shingare, M. S. Green Chem. Let. Rev. 2010, 3, 83–87. DOI: 10.
1080/17518250903567246.
[7] Uredi, D.; Reddy, M. D.; Watkins, E. B. Chem. Commun. (Camb.) 2019, 55, 3270–3273.
DOI: 10.1039/c9cc01097a.
[8] (a) Khavasi, H. R.; Sadegh, B. M. M. Dalton Trans. 2015, 44, 5488–5502. DOI: 10.1039/
C4DT03518F. (b) Eryazici, I.; Moorefield, C. N.; Durmus, S.; Newkome, G. R. J. Org.
Chem. 2006, 71, 1009–1014. DOI: 10.1021/jo052036l.
€
[9] (a) Krohnke, F. Synthesis 1976, 1, 1–24. DOI: 10.1055/s-1976-23941. (b) Sasaki, I.
Synthesis 2016, 48, 1974–1992. DOI: 10.1055/s-0035-1561974.
[10] Ladani, N. K.; Patel, M. P.; Patel, R. G. Phosphorus, Sulfur, and Silicon Relat. Elem. 2010,
185, 658–662. DOI: 10.1080/10426500902915507.
[11] Yan, C.-G.; Cai, X.-M.; Wang, Q.-F.; Wang, T.-Y.; Zheng, M. Org. Biomol. Chem. 2007, 5,
945–951. DOI: 10.1039/b617256c.
[12] Yan, C.-G.; Wang, Q.-F.; Cai, X.-M.; Sun, J. Cent. Eur. J. Chem. 2008, 6, 188–198.
[13] Wang, Q.-F.; Yan, C.-G. Chem. Res. Chin. Univ. 2009, 25, 338–342. DOI: 10.1007/s40242-
018-8014-4.
[14] Ganis, P.; Saporito, A.; Vitagliano, A.; Valle, G. Inorganica Chim. Acta. 1988, 142, 75–79.
DOI: 10.1016/S0020-1693(00)80661-1.
[15] (a) Shrestha, A.; Park, S.; Shin, S.; Kadayat, T. M.; Bist, G.; Katila, P.; Kwon, Y.; Lee, E.-S.
Bioorg. Chem. 2018, 79, 1–18. DOI: 10.1016/j.bioorg.2018.03.033. (b) Kadayat, T. M.;
Park, S.; Jun, K.-Y.; Magar, T. B. T.; Bist, G.; Yoo, H. Y.; Kwon, Y.; Lee, E.-S. Eur. J. Med.
Chem. 2015, 90, 302–314. DOI: 10.1016/j.ejmech.2014.11.046.
ꢀ
[16] LeGourrierec, D.; Kharlanov, V.; Brown, R. G.; Rettig, W. J. Photochem. Photobiol. A
Chem. 1998, 117, 209–216. DOI: 10.1016/S1010-6030(98)00328-1.

10
S. BATALIN ET AL.
[17] Olekhnovich, E. P.; Korobka, I. V.; Borodkin, G. S.; Makarova, N. I.; Knyazhanskii, M. I.
Russ. J. Org. Chem. 1996, 32, 1055–1058. DOI: 10.1002/chin.199718169.
[18] (a) Rahman, A. F. M. M.; Ali, R.; Jahng, Y.; Kadi, A. A. Molecules 2012, 17, 571–583.
DOI: 10.3390/molecules17010571. (b) Kumar, S.; Kumar, P.; Makrandi, J. K. Der Chem.
Sin. 2012, 3, 269–273.
[19] (a) Karimi-Jaberi, Z.; Pooladian, B. Green Chem. Let. Rev. 2012, 5, 187–193. DOI: 10.
1080/17518253.2011.611478. (b) Hasaninejad, A.; Zare, A.; Balooty, L.; Mehregan, H.;
Shekouhy, M. Synth. Commun. 2010, 40, 3488–3495. DOI: 10.1080/00397910903457282.
(c) Wei, X.; Du, Z.-Y.; Zheng, X.; Cui, X.-X.; Conney, A. H.; Zhang, K. Eur. J. Med.
Chem. 2012, 53, 235–245. DOI: 10.1016/j.ejmech.2012.04.005.
[20] Cao, Y.-Q.; Dai, Z.; Zhang, R.; Chen, B.-H. Synth. Commun. 2005, 35, 1045–1049. DOI:
10.1081/SCC-200054198.
[21] (a) Nuriev, V. N.; Vatsadze, I. A.; Sviridenkova, N. V.; Vatsadze Rus, S. Z. J. Org. Chem.
2016, 52, 389–396. (b) Gulai, T. V.; Morozova, A. A.; Golikov, A. G. Russ. J. Org. Chem.
2011, 47, 1690–1694. DOI: 10.1134/S1070428011110066. (c) Sheikhhosseini, E.; Farrokhi,
E.; Bigdeli, M. A. J. Saudi Chem. Soc. 2016, 20, 227–230. (d) El-Subbagh, H. I.; Abu-Zaid,
S. M.; Mahran, M. A.; Badria, F. A.; Al-Obaid, A. M. J. Med. Chem. 2000, 43, 2915–2921.
DOI: 10.1021/jm000038m.
[22] Dykun, A. M.; Anishchenko, V. N.; Redko, A. N.; Rybachenko, V. I.; Chotiy, K. Y. J. Mol.
Struct. 2019, 1179, 289–296. DOI: 10.1016/j.molstruc.2018.11.028.
[23] Stekhova, S. A.; Lapachev, V. V.; Mamaev, V. P. Chem. Heterocycl. Compd. 1990, 26,
65–70.
[24] Kim, D. H.; Rahman, A. F. M. M.; Jeong, B.-S.; Lee, E. S.; Jahng, Y. Bull. Korean Chem.
Soc. 2009, 30, 797–802.