2-DIETHYLAMINOVINYL DERIVATIVES OF HALOGENATED 1,4-QUINONES: SYNTHETIC AND STRUCTURAL ASPECTS

Article abstract of DOI:10.1134/S0022476620080107

Abstract: Diethylaminovinyl derivatives of halogenated 1,4-quinones (enaminoquinones) are produced by the interaction of halogenated 1,4-quinones with N,N-diethyl-N-vinylamine obtained in situ from Et₂NH and MeCHO. Molecular and crystal structu

Full text of DOI:10.1134/S0022476620080107

ISSN 0022-4766, Journal of Structural Chemistry, 2020, Vol. 61, No. 8, pp. 1253-1259. © Pleiades Publishing, Ltd., 2020.
Russian Text © The Author(s), 2020, published in Zhurnal Strukturnoi Khimii, 2020, Vol. 61, No. 8, pp. 1321-1327.
2-DIETHYLAMINOVINYL DERIVATIVES
OF HALOGENATED 1,4-QUINONES: SYNTHETIC
AND STRUCTURAL ASPECTS
S. I. Zhivetyeva1*, I. A. Zayakin1,
I. Yu. Bagryanskaya1,2, and E. V. Tretyakov1,2
Diethylaminovinyl derivatives of halogenated 1,4-quinones (enaminoquinones) are produced by the
interaction of halogenated 1,4-quinones with N,N-diethyl-N-vinylamine obtained in situ from Et2NH and
MeCHO. Molecular and crystal structures of enaminoquinones halogenated in the quinone fragment are
determined. It is shown that in the solid phase, atoms of the entire push-pull system of enaminoquinones lie
practically in one plane.
DOI: 10.1134/S0022476620080107
Keywords: N-vinylamines, halogenated 1,4-quinones, enaminoquinones, crystal structure, hydrogen bond,
π-stacking.
INTRODUCTION
Organic molecules with conjugated acceptor quinone fragment Q and donor amine function NR2 can be designated
by the general formula Q–Sp–NR2, where Sp is an unsaturated bridging fragment. These compounds are promising for the use
in nonlinear optical blocks [1-5], molecular electronic devices [6-8], and also systems modeling the work of natural
photosynthetic centers [9-12].
The family of the Q–Sp–NR2 structure type still contains insufficiently studied but interesting types of compounds.
Enaminoquinones QHal–CH=CH–NR2 with a halogenated quinone fragment QHal, which not only enhances the push-pull
character of the QHal–CH=CH–NR2 system but also opens new ways to functionalize the quinone core, belong to them [13-
15]. The aim of this work was the synthesis of 2-diethylaminovinyl-1,4-quinones QHal–CH=CH–NEt2 with different QHal and
the analysis of their structure and packing.
EXPERIMENTAL
1
19
1
Materials and methods. Н and F NMR spectra were measured on a Bruker AV-300 spectrometer ( Н operating
19
frequency 300.13 MHz, F operating frequency 282.36 MHz); CDCl3 (H 7.24 ppm) and C6F6 (F 162.9 ppm with respect to
CFCl3) were used as the internal standards. Melting points were determined on a Mettler Toledo apparatus with a FP 900
Thermosystem cell and were not corrected. The C, H, N elemental analysis was conducted on a Carlo Erba Model 1106,
1
Vorozhtsov Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia;
2
*zhivietsv@nioch.nsc.ru. Novosibirsk State University, Novosibirsk, Russia. Original article submitted January 29, 2020;
revised March 11, 2020; accepted March 13, 2020.
0022-4766/20/6108-1253 © 2020 by Pleiades Publishing, Ltd.
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F instrument by spectrophotometry. Accurate masses of molecular ions were determined on a high-resolution Thermo
Scientific DFS mass spectrometer (Double Focusing Sector Mass Spectrometer, DFS High Resolution GC/MS). IR spectra
were measured on a Vector-22 instrument from the samples pressed in pellets with KBr. UV spectra were recorded on a
Cary5000 apparatus in methylene chloride. The reaction course and the purity of products were controlled by thin-layer
chromatography (TLC) on Merck Silica gel 60 F254с plates. Silica gel (50-160 mesh) was applied for chromatography.
Amines Et2NH, Et3N, as well as solvents were distilled before the use. Acetaldehyde was used without preliminary
purification.
Synthesis of (E)-2-(2-(diethylamino)vinyl)-3,5,6,7,8-pentafluoronaphthalene-1,4-dione (8). To a solution of
quinone 5 (0.050 g, 0.188 mmol) in CH2Cl2 (2.0 mL) a solution of Et2NH (0.014 g, 0.188 mmol) and MeCHO (0.026 g,
0.590 mmol) in CH2Cl2 (2.0 mL) was added. The reaction mixture was stirred for 1 h at room temperature and then
evaporated at lowered pressure. The residue was purified by TLC (silica gel Merck on a glass plate, 1:2 Et2O–hexane) and
0.021 g (32%) of quinone 8 as blue crystals and 0.020 g (34%) of quinone 9 [16] as red oil were obtained.
19
8: m.p. 189.7 °C (with decomposition). UV (CH2Cl2) λmax, nm (lgε): 599 (4.07), 331 (4.40). F NMR (CDCl3, δ,
3
ppm, J, Hz): 30.93 (br. s., 1F, F ), 22.60 (m., 2F, F ), 16.70 (m., 1F, F or F ), 14.24 (m., 1F, F or F ). H NMR (CDCl3,
5,8
6
7
6
7
1
3
3
3
δ, ppm, J, Hz): 7.90 (d.d., 1H, CH, JHH = 13.4, J = 2.6), 5.24 (d., 1H, CH, JHH = 13.4), 3.35 (q., 4H, 2CH2, JHH = 7.1), 1.24
3
–1
(t., 6H, 2CH3, JHH = 7.1). IR, cm : 2987, 2962, 2945, 2879, 1678, 1649, 1614, 1585, 1547, 1502, 1470, 1454, 1435, 1381,
1365, 1340, 1313, 1250, 1184, 1147, 1126, 1095, 1078, 1051, 1018, 987, 966, 953, 933, 841, 822, 802, 787, 764, 611, 550.
+
+
Found [М] 345.0780. Calculated [М] for С16H12F5NO2 345.0783. Found (%): С 55.55, H 3.78, N 3.65. Calculated for
С16H12F5NO2 (%): С 55.66, H 3.50, N 4.06.
The synthesis of 2,3,5-tribromo-6-(2′-(diethylamino)vinyl)-benzo-1,4-quinone (2b, 18%) [17] from bromanil and
2-diethylaminovinyl-3-bromo-1,4-narhthoquinone (4b, 35%) from 2,3-dibromo-1,4-naphthoquinone 6 was performed by the
similar procedure. In 1 h, a reaction of 2-methoxypentafluoro-1,4-naphtnoquinone resulted in a mixture of initial quinone and
unidentified products.
The single crystal X-ray diffraction (XRD) study of compounds 2b, 4b, and 8 was conducted on an automated
Bruker KAPPA APEX II CCD diffractometer: graphite monochromator; λMoKα = 0.71073 Å; ω–ϕ scanning; temperature
296 K. Absorption correction was applied semi-empirically using the SADABS program [18]. The structures were solved by
a direct method using the SHELXT-2014/5 program [19] and refined first in the isotropic and then anisotropic
approximations using the SHELXL-2014/7 program [19]. Hydrogen atoms in the structures were placed in geometrically
calculated positions and refined by the riding model. The main parameters of the single crystal XRD experiment are listed in
Table 1. The figures were drawn and the analysis of intermolecular interactions was carried out using the PLATON [20] and
MERCURY [21] programs, respectively.
Full tables of interatomic distances and bond angles, atomic coordinates and displacement parameters have been
deposited with the Cambridge Crystallography Data Center (CCDC 1971279, 1971280, 1971281 for 2b, 4b, 8 respectively;
deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).
RESULTS AND DISCUSSION
It has been previously shown that 2-diethylaminovinyl-1,4-quinones 1b, 2b formed with a low yield (NMR yield
∼70% and ∼60%, product yield ∼50% and ∼40% for 1b and 2b respectively) in the interaction of Et3N with tetrachloro- and
tetrabromo-1,4-benzoquinones in benzene [15]. The interaction of 2,3-dibromonaphtho-1,4-quinone with Et3N in CH2Cl2 by
the above described procedure yielded 2-diethylaminovinyl-1,4-quinone 4b only in trace amounts [22]. A low yield of
quinones 1b, 2b, and 4b is due to two factors: firstly, a part of initial quinones was consumed to oxidize Et3N to enamine in
the reaction; secondly, the lability of formed enaminoquinones that partially decomposed during isolation processes.
A more efficient method for preparing 2-dialkylaminovinyl-1,4-quinones was described by Henbest and coworkers.
It consisted in the interaction of halogenated para-quinone with an equivalent amount of acetic or crotonic aldehyde and two
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TABLE 1. Crystallographic Data and Details of the Single Crystal XRD Experiment
Parameter
2b
4b
8
Chemical formula
Formula weight
C12H12Br3NO2
441.96
C16H16BrNO2
334.21
C16H12F5NO2
345.27
Crystal system
Triclinic
Monoclinic
P21/с; 4
7.9468(4),
18.2894(8),
10.4268(4);
90,
Triclinic
Space group; Z
P-1; 2
P-1; 2
Unit cell parameters: a, b, c, Å;
7.3381(3),
10.6657(4),
10.6823(4);
62.980(2),
70.854(2),
84.943(2)
701.76(5)
2.092
8.1031(12),
9.8177(13),
9.8306(13);
106.744(6),
103.086(6),
97.146(6)
714.2(2)
α, β, γ, deg
105.243(2),
90
3
V, Å
1462.1(1)
1.518
3
d
calc, g/cm
–1
μ, mm
1.605
8.615
2.812
0.149
2.15-30.04
2.23-27.60
2.21-25.78
θ range, deg
Reflections measured / unique
14287 / 3724
(0.0512)
22872 / 3379
(0.0517)
11774 / 2715
(0.0641)
(Rint)
3075
0.0435, 0.0988
0.0553, 0.1062
1.009
2349
0.0584, 0.1553
0.0902, 0.1859
1.043
1410
0.0541, 0.0968
0.1295, 0.1191
1.023
Observed reflections with I > 2σ(I)
R1, wR2 over I > 2σ(I)
R1, wR2 over unique reflections
GOOF
CCDC
1971279
1971280
1971281
equivalents of Alk2NH in a benzene or water-dioxane solution. Both enaminoquinones and products of the dialkylamino
group substitution for the halogen atom formed here [23]. In order to avoid the formation of the latter, Fokin and coauthors
[24] proposed a modified procedure, according to which, an aqueous dialkylamine solution (R2NH, R = Me, Et) was
gradually added to a solution of 1,4-quinone and aldehyde in aqueous dioxane at pH 6-7. Under these conditions, respective
enaminoquinones 1a and 3a were obtained with a yield of 70-86% [24] (Scheme 1). Later it was shown that the use of the
inverse order of adding the reagents, namely, the addition of the amine and aldehyde solution to the solution of 1,4-quinone in
toluene also resulted in target 2-dialkylaminovinyl-1,4-quinones 1a, b, 2b, and 3b with high yields (67-90%) [17] (Scheme 1).
Scheme 1.
Having analyzed the available methods for obtaining enaminoquinones, we selected the variant with the inverse
order of mixing reagents and used it, including for the preparation of previously unknown polyfluorinated enaminoquinone 8.
Under the optimized conditions (EXPERIMENTAL), namely, by the interaction of hexafluoro-1,4-naphthoquinone 5 with
a solution of Et2NH (1 eq.) and MeCHO (3.1 eq.) in CH2Cl2, we managed to obtain enaminoquinone 8 with a yield of 32%
(Scheme 2). Here, along with 8 as a by-product naphthoquinone 9 formed (34%). Under similar conditions, 2,3-dibromo-1,4-
naphthoquinone 6 gave 2-diethylaminovinyl-3-bromo-1,4-naphthoquinone 4b with a 35% yield.
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Scheme 2.
Crystals of compounds 2b and 4b were grown from a dichlorometane–heptane (1:1) mixture at –5 °C for 30 and 7
days respectively. Crystals of compound 8 were grown for 7 weeks in a closed bottle from benzene by gas exchange with
hexane at room temperature.
According to the single crystal XRD data, the tribromobenzoquinone fragment in 2b as well as 2-bromo-1,4-
naphthoquinone fragment in 4b and pentafluoro-1,4-naphthoquinone one in 8 are almost planar. The mean average square
deviation from the plane drawn through all non-hydrogen atoms of these fragments is 0.070 Å, 0.032 Å, and 0.036 Å for 2b,
4b, and 8 respectively. In all three compounds, the aminovinyl fragment is also planar and lies in the same plane as the
tribromobenzoquinone fragment in 2b, the 2-bromo-1,4-naphthoquinone fragment in 4b, and pentafluoro-1,4-naphthoquinone
one in 8. In the molecules of compounds 2b and 8, ethyl groups are directed in different sides from the plane in which the
other atoms lie, whereas in the 4b molecule, ethyl groups are located at one side of the plane in which the other atoms lie.
Fig. 1 depicts the molecular structures of 2b, 4b, 8 molecules; their geometric parameters correspond to average statistical
values in the 3σ limit [25]. Intermolecular interactions were analyzed using the PLATON [20] and MERCURY [21]
programs.
Fig. 1. Molecular structures of enaminoquinones 2b, 4b, and 8.
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The conjugated molecules having a planar structure are characterized by the stacked packing, including π-stacking
interactions [26]. The occurrence of substituents often leads to significant lateral displacements of the neighboring molecules
in the stacks. Just this situation is also observed for the crystal packing of compound 2b (Fig. 2) where the molecules are
packed with the formation of a staircase structure instead of stacks. The distance between the centroids of the neighboring
molecules in the stack is 3.965(2) Å, and О…π and Br…π interactions are observed instead of π-stacking interactions (О1
and Br3 atoms interact with the π-system of the benzoquinone fragment of the neighboring chains). The distance from the О1
atom to the centroid (Сg) is 3.504(4) Å and the distance from the Br3 atom to Сg is 3.922(2) Å. There are weak С9–H…О1
hydrogen bonds between the neighboring stacks-staircases along the c axis (Fig. 2); parameters of these bonds are given in
Table 2. A polychlorinated analog of compound 2b was found in CCDC [27] whose crystal packing is similar to that of 2b
because of the presence of stacks with a large lateral displacement, inside which there are О…π and Cl…π interactions.
The crystal structure of compound 4b has the stacking character (head-to-tail) due to π-stacking interactions between
the π-systems of naphthoquinone fragments with the Cg…Cg distance of 3.737(2) Å and the interplanar distance of 3.49 Å,
which is supplemented by the О…π interaction with the О1 atom…centroid (Cg) distance of 3.692(5) Å (Fig. 3). The
neighboring stacks are packed in tiles and linked with each other by weak С7–H…О1 and С9–H…О1 hydrogen bonds
(Table 2). In CCDC there is a close analog of compound 4b which is distinct in that it contains a quinoline-5,6-dione
fragment instead of the naphthoquinone one [28]. Despite that the crystals of compounds with naphthoquinone and quinoline-
5,6-dione fragments are practically isostructural, a substantially larger lateral displacement is observed in the heterocyclic
derivative (the minimum distance between the centroids of the neighboring molecules is 4.490 Å).
Fig. 2. Fragment of the crystal structure of enaminoquinone 2b.
TABLE 2. Parameters of Hydrogen Bonds in Compounds 2b and 4b
Parameter
Compound
Interaction
Н…О, Å
С…О, Å
С–Н…О, deg
2b
4b
C9–H9а⋯O1
C7–H7⋯O1
C9–H9b⋯O1
2.59
2.47
2.59
3.207(7)
3.278(7)
3.508(8)
121
145
157
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Fig. 3. Fragment of the crystal structure of enaminoquinone 4b.
Fig. 4. Fragment of the crystal structure of polyfluorinated quinone 8.
The crystal packing of compound 8 is characterized by the presence of the π-stacking interaction between π systems
of naphthoquinone fragments with the Cg…Cg distance of 3.634(2) Å and the interplanar distance of 3.27 Å. The F…π and
О…π interactions with the F1…centroid (Cg) distance of 3.334(2) Å [29] and the О1…centroid (Cg) distance of 3.399(2) Å
are also observed in these stacks (Fig. 4). Unlike 2b and 4b, in the crystal structure of 8, hydrogen bonds are absent.
CONCLUSIONS
Thus, in this work, diethylaminovinyl derivatives of halogenated 1,4-quinones were synthesized. It is shown that the
reaction of polyfluorinated 1,4-naphthoquinones with in situ obtained N,N-diethyl-N-vinylamine gives a product with
enamine substitution for the fluorine atom in the quinone ring. Molecular and crystal structures of diethylaminovinyl
derivatives of halogenated 1,4-quinones are solved. The obtained data can be used to deduce correlations between the
structure and optical characteristics of QHal–CH=CH–NR2 systems.
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ACKNOWLEDGMENTS
The authors are thankful to the Chemical Service Center of the Institute of Organic Chemistry, Siberian Branch,
Russian Academy of Sciences for performing the single crystal XRD analysis.
FUNDING
The study was supported by the Russian Science Foundation (project No. 17-73-10238).
CONFLICT OF INTERESTS
The authors declare that they have no conflict of interests.
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