Synthesis, structure, electrochemistry, and photophysics of 2,5-dibenzylidenecyclopentanones containing in benzene rings substituents different in polarity

Article abstract of DOI:10.1007/s11172-016-1508-7

A series of cross-conjugated dienones was synthesized to study the dependence of physicochemical characteristics on the nature of substituents in the aromatic groups of symmetric cyclopentanone dibenzylidene derivatives. The structure of compounds was established by electronic, IR, and NMR spectroscopy and X-ray diffraction study. All the compounds obtained possess the E,E-geometry. In the crystalline state, the arrangement of the dienone molecules is unfavorable for the intermolecular [2+2] photocycloaddition to take place. The low-temperature phases transition for unsubstituted diphenyl derivative of cyclopentanone was detected using variable-temperature X-ray diffraction and differential scanning calorimetry. Oxidation and reduction potentials of the dienones were measured by cyclic voltammetry. Their dependence on the nature and placement of substituents in the benzene rings was demonstrated. A linear correlation (R = 0.9343) between the difference of electrochemical oxidation and reduction potentials and the energy of the long-wavelength absorption maximum was found, that allows us to recommend the use of the data obtained in the correlation analysis of other compounds of this class.

Full text of DOI:10.1007/s11172-016-1508-7

Russian Chemical Bulletin, International Edition, Vol. 65, No. 7, pp. 1761—1772, July, 2016
1761
Synthesis, structure, electrochemistry, and photophysics
of 2,5ꢀdibenzylidenecyclopentanones containing in benzene rings substituents
different in polarity*
S. Z. Vatsadze,a G. V. Gavrilova, F. S. Zyuz´kevich, V. N. Nuriev, D. P. Krut´ko, A. A. Moiseeva,
a
b
a
a
a
a
b
c
c
d
a,b
A. V. Shumyantsev, A. I. Vedernikov, A. V. Churakov, L. G. Kuz´mina, J. A. K. Howard, and S. P. Gromov
aM. V. Lomonosov Moscow State University, Department of Chemistry,
Build. 3, 1 Leninskie Gory, 119991 Moscow, Russian Federation.
Fax: +7 (495) 932 8846. Eꢀmail: szv@org.chem.msu.ru
b
Center of Photochemistry, Russian Academy of Sciences,
7
Aꢀ1 ul. Novatorov, 119421 Moscow, Russian Federation.
Fax: +7 (495) 936 1255. Eꢀmail: spgromov@mail.ru
c
N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
3
1 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (495) 954 1279
d
Chemistry Department, Durham University, South Road, Durham DH1 3LE, UK.
A series of crossꢀconjugated dienones was synthesized to study the dependence of physicoꢀ
chemical characteristics on the nature of substituents in the aromatic groups of symmetric
cyclopentanone dibenzylidene derivatives. The structure of compounds was established by
electronic, IR, and NMR spectroscopy and Xꢀray diffraction study. All the compounds
obtained possess the E,Eꢀgeometry. In the crystalline state, the arrangement of the dienone
molecules is unfavorable for the intermolecular [2+2] photocycloaddition to take place. The
lowꢀtemperature phases transition for unsubstituted diphenyl derivative of cyclopentanone was
detected using variableꢀtemperature Xꢀray diffraction and differential scanning calorimetry.
Oxidation and reduction potentials of the dienones were measured by cyclic voltammetry.
Their dependence on the nature and placement of substituents in the benzene rings was demonꢀ
strated. A linear correlation (R = 0.9343) between the difference of electrochemical oxidation
and reduction potentials and the energy of the longꢀwavelength absorption maximum was
found, that allows us to recommend the use of the data obtained in the correlation analysis of
other compounds of this class.
Key words: dienones, synthesis, NMR spectroscopy, Xꢀray diffraction, differential scanꢀ
ning calorimetry, supramolecular chemistry, [2+2] photocycloaddition, CVA, electronic
spectroscopy, correlation analysis.
Extremely large synthetic potential of carbonꢀcarbon
double bond conjugated with a carbonyl group has been
successfully used in organic chemistry for a long time.
ed dienones with pyridine substituents became widely used
as ligands for obtaining discrete and polymeric coordinaꢀ
tion compounds.
1
7—9
Michael reaction and its numerous variations are a typical
example of this. The conjugation of two double bonds
Besides participation in addition reactions, the double
bonds of dienones also substantiate two important specific
features of this class of compounds. First, an inherent
property of the dienones is their existence in the form of
Eꢀ and Zꢀisomers, the interconversion of which can be
initiated upon influence of different factors, such as light,
2
with a keto function makes possible a number of additional
3
transformations. Such compound called the crossꢀconꢀ
jugated dienones or (less frequently) ketone diarylidene
derivatives attract attention of scientists by their rich synꢀ
thetic chemistry and wide applied possibilities, first of all,
1
0—14
acids, transition metals.
As a rule, a E,Eꢀisomer
4
—6
in biology and agriculture.
Lately, the crossꢀconjugatꢀ
is the most stable in a number of cyclopentanone and
cyclohexanone derivatives. The percentage of E,Zꢀ and
Z,Zꢀisomers increases with the increase in the ring size.4
The second important property of this class of comꢀ
pounds is their ability to undergo [2+2] photocycloaddiꢀ
,12
*
Based on the materials of the International Congress on the
Heterocyclic Chemistry "KOSTꢀ2015" (October 18—23, 2015,
Moscow, Russia).
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1761—1772, July, 2016.
066ꢀ5285/16/6507ꢀ1761 © 2016 Springer Science+Business Media, Inc.
1

1
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Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
Vatsadze et al.
tion reactions (PCA),12,15,16 and in the case of free diꢀ
enones such transformations can take place both in crystal
and in solution. The possibility of PCA and their stereoseꢀ
lectivity can be controlled using supramolecular preorgaꢀ
tion and reduction potentials in order to find out the deꢀ
pendences of energy characteristics of the molecules on
placement, nature, and number of substituents. Apart from
that, we attempted to find out the existance of any correꢀ
lation between electrochemical and photophyical characꢀ
teristics of dienones 1a—g.
nization of the double bonds for the development of the
most suitable geometry of a preceding dimer.1
7—19
In the
case of the crystalline forms of pyridine derivatives, such
transformations can be effected using supramolecular temꢀ
Results and Discussion
2
0
plation by metal complexes, resorcinol (pyridineꢀconꢀ
taining monoenones21 and acyclic dienones ) or upon
treatment with silver ions (only pyridineꢀcontaining acyclic
dienones have been studied).2
22
Compounds 1a—g were synthesized using a procedure
of the alkaline aldolꢀcrotonic condensation of cyclopenꢀ
tanone with two equivalents of substituted benzaldehyde
3
For implementation of the project on development of
supramolecular systems capable of photoswitching, we
began a comprehensive study of crossꢀconjugated dienones
containing ionophoric substituents, for example, crown
ethers.2 The purpose of this study is the development of
hybrid molecules combining two functional centers in one
structure: an ionophoric one capable of coordination with
metal ions, ammonium, and other analytes, and a photoꢀ
switching one necessary for implementation of controlled
coordination using an external treatment with light. For
deeper understanding of occurring photochemical transꢀ
formations, it is necessary to in detail study properties of
model compounds and their physicochemical characꢀ
teristics. Apart from that, it was necessary to find out
whether the PCA reaction can proceed in crystal and in
solution without supramolecular preorganization of reactꢀ
ing double bonds.
1
2
(
Claisen—Schmidt reaction, Scheme 1).
Scheme 1
4
All the compounds 1a—g were isolated as brightly colꢀ
ored crystalline substances. All the compounds, except 1c
and 1f, were characterized by Xꢀray diffraction data (for
details, see below), from which it follows that all the dienꢀ
ones are formed as E,Eꢀisomers. A similar conclusion can
be drawn from the NMR spectroscopy data.
The chemical shifts for the olefin protons in dienones
a—g lying in the range of δ 7.51—7.60, correspond to the
E,Eꢀisomers. Note that the chemical shifts of the
nuclei of the bisꢀmethylidenecyclopentanone fragment in
compounds 1a—g change very little upon introduction of
substituents in the aromatic rings. The only exception was
a small (~2 ppm) upfield shift of the signals for the carbon
nuclei next to the carbonyl group in dialkylamino derivaꢀ
tives 1b and 1c as compared to other compounds.
Since one of the methods of supramolecular organizaꢀ
tion of dienones is their reaction with Brønsted acids,
it was important to find out how the obtained compounds
behave upon protonation both in solvents and in solid
phase. It should be noted that acidochromism in substiꢀ
1
In the present work, we synthesized and studied diꢀ
enones 1a—g, differing in the nature and the number of
alkylthio, dialkylamino, and alkoxy substituents. The
structures under study are chromophoric models of the
corresponding crown ethers and aza/thiaꢀcrown ethers.
The cyclopentanone moiety was chosen as a central fragꢀ
ment, since it is known that dienone derivatives of cycloꢀ
pentanone are characterized by high degree of conjugation
of all the multiple bonds because of almost ideally planar
conformation of the molecules.12
12
13
C
20—23
2
5,26
tuted dienones has been observed earlier.
After a number of preliminary experiments with differꢀ
ent in strength organic and mineral acids, our choice fell
on trichloroacetic acid, since in this case the changes obꢀ
served were the most illustrative. In the experiments in
solution, the changes in the presence of CCl COOH were
analyzed by NMR spectroscopy. The addition of 1 equiv.
3
1
1
: R = H (a), NMe (b), NEt (c), SMe (d), OMe (e—g);
2
2
2
R = H (a—e), OMe (f), OEt (g)
of CCl COOH to solutions of 1a, 1d, and 1e in CDCl
3
3
The structures of the synthesized compounds were esꢀ
leads to a reversible protonation at the carbonyl group,
with the equilibrium being strongly shifted to the side of
the starting ketone. Noticeable changes in the chemical
shifts were observed only for the C=O group and the =CH
tablished by electronic, IR, and NMR spectroscopy, as
well as by Xꢀray diffraction. The latter method was used to
find out how favorable the double bonds of the neighborꢀ
ing molecules are arranged for the PCA reaction to occur
in crystal. Cyclic voltammetry was used to obtain oxidaꢀ
fragment (in both cases this was a downfield shift of δ by
C
~2—3 ppm and δ by ~0.1 ppm). The effect was considerꢀ
H

2
,5ꢀDibenzylidencyclopentanones
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
1763
ably lower when TsOH was used. In the case of ketone 1b,
the reaction with both acids involved only the dimethyꢀ
lamino group.
NMR data given above. Thus, a conclusion can be drawn
that the basicity of compounds 1a, 1d, and 1e is very low,
therefore, in dilute solutions the equilibrium of the protoꢀ
nation at the carbonyl group is considerably shifted to the
side of the starting ketones. In the case of ketone 1b, the
protonation mainly occurs at the amino groups.
In the absence of solvent, the addition of one or more
equivalents of CCl COOH to compounds 1a, 1b, 1d, and
3
1
e with subsequent mechanical trituration leads to the
formation of brightly colored powdered products (similar
The data obtained can be used in future in the design of
supramolecular templates suitable for carrying out directꢀ
ed reactions of crossꢀconjugated dienones.
changes take place upon addition of an excess of HClO ).
4
In the IR spectra of these products in Nujol (except for the
reaction of 1b with CCl COOH), the band of the stretchꢀ
The Xꢀray diffraction studies confirmed the NMR
spectroscopy data on the formation of only E,Eꢀisomers
in the case of dienone molecules (Fig. 1 and 2, Table 1).
Compound 1b was obtained in the nonꢀsolvate form (by
growing crystals from a CH Cl —hexane solvent mixture)
3
–
1
ing vibrations of the carbonyl group (~1700 cm ) disꢀ
appears simultaneously with the change in the general
pattern of the spectrum. In the case of compound 1b, the
band does not shift, but considerably broadens. When
TsOH is used, the position of the vibration band of C=O
remains unchanged, but its intensity decreases.
2
2
and as a solvate with the CHCl molecule (by growing
3
from chloroform). Note that the crystal structures of diꢀ
2
7,28
28
29
Electronic absorption spectra of the solutions of ketones
enones 1a
, 1e, and 1f were studied earlier at room
1
a, 1b, 1d, and 1e treated with an excess of CCl COOH
temperature. In the present work, we obtained similar crysꢀ
tallographic parameters and packing motives for comꢀ
3
correspond to the initial ones. These facts agree with the
C(10A)
C(9A)
C(2)
C(5)
C(20)
C(1)
O(1)
C(3)
C(4)
C(4A)
N(1)
O(1)
C(9)
C(8A)
C(7A)
C(5A)
C(2A)
C(1)
C(8)
C(7)
C(6A)
C(4)
C(5)
C(6)
C(21)
C(13)
C(2)
C(3)
C(10)
C(9)
C(3A)
C(12) C(10)
C(11)
C(15)
C(14)
C(19)
C(16)
C(6)
C(8)
C(17)
C(18)
C(22)
N(2)
C(7)
1
a
1b
Cl(1A)
C(6A)
C(23)
C(11)
Cl(2A)
Cl(3A)
C(10)
C(9)
C(2)
N(1)
S(1)
C(19)
C(20)
C(8)
C(7)
O(1)
C(4)
C(5)
C(18)
C(17)
C(14)
O(1)
C(1)
C(15)
C(12)
C(13)
C(6)
C(2)
C(3)
C(1)
C(3)
C(16)
C(2A)
C(22)
C(4A)
C(24)
C(25)
C(26)
C(30)
C(3A)
C(23)
C(5A)
C(10A)
C(29)
C(6A)
C(7A)
C(9A)
C(27)
C(28)
C(5)
C(8A)
S(1A)
C(4)
C(11A)
N(2)
1
b•CHCl3
1d
Fig. 1. The molecular structures of compounds 1a (a highꢀtemperature phase), 1b, 1b•CHCl , and 1d. Thermal ellipsoids are shown
3
with 50% probability.

1
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Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
Vatsadze et al.
C(2S)
C(2´)
C(4´)
C(20´)
O(1´)
C(3´)
C(1´)
O(3´)
C(9´)
C(1S)
N(1S)
C(7´)
C(9A)
O(2A)
C(5´)
C(8´)
C(11A)
O(2´)
C(6´)
C(10´)
C(10A)
C(13´)
C(17´)
C(15´)
C(16´)
C(12´)
C(21´)
C(8A)
C(7A)
C(5A)
C(14´)
C(4A)
O(1)
C(1)
C(11´)
C(19´)
C(22´)
C(6A)
C(2A)
C(18´)
C(23´)
O(4´)
C(20)
C(24´)
O(5´)
C(3A)
C(3)
C(4)
C(2)
C(4)
C(2)
C(5)
C(1)
C(25´)
C(3)
C(10)
C(9)
O(1)
O(3)
C(7) C(8)
C(6) C(5)
C(6)
C(7)
C(9)
O(2)
C(8)
C(10)
C(21)
C(13)
C(18)
C(12)
O(2)
C(11)
C(14)
1
e
C(11)
C(22)
C(15)
C(16)
C(19)
C(24)
C(17)
O(5) O(4)
C(25)
C(23)
1
g•0.5MeCN
Fig. 2. The molecular structures of compounds 1e and 1g•0.5 MeCN (two independent molecules). Thermal ellipsoids are shown with
0% probability.
5
pounds 1a (a highꢀtemperature phase) and 1e, but experiꢀ
ments were carried out on cooling to 120—240 K.
In the structures of compounds 1a (a highꢀtemperaꢀ
ture phase), 1d, and 1e, the dienone molecules are located
on the second order crystallographic axes, while in the
structures 1a (a lowꢀtemperature phase), 1b, 1b•CHCl3,
and 1g•0.5MeCN they are in general positions. In most
cases, the molecules are virtually planar, with the angle of
turning around the central bond of the =C—Ar fragment
being no larger than 9°. Only for one aryl substituent in
Table 1. Geometric parameters of compounds 1a, 1b, 1b•CHCl , 1d, 1e, and 1g•0.5MeCN
3
1
2
Compound
d(C=O) d(C(O)—C) d(C=CHAr) d(CH—CAr
)
θ(C=CH—C —C ) d(C –R ) d(C —R )
Ar
Ar
Ar
Ar
/
deg
Å
Å
1
a*
1.234(11) 1.450(11),
.484(13)
1.350(13),
1.358(11)
1.346(4)
1.342(10),
1.329(10)
1.362(4),
1.347(4)
1.339(4)
1.347(2)
1.340(4),
1.345(4),
1.346(4),
1.350(4)
1.512(13),
2.7, 3.0
1.—
1.—
1
1.456(13)
1.452(5)
1.452(11),
1.424(10)
1.438(4),
1.450(4)
1.466(4)
1.461(2)
1.466(4),
1.464(4),
1.453(4),
1.461(4)
1
1
a**
b
1.224(5)
1.254(9)
1.471(4)
1.491(11),
3.1
5.4, –5.5
1.—
1.—
1.—
1.372(9),
1.381(9)
1.363(4)
1
.472(10)
1.469(4),
.472(4)
1
b•CHCl3
1.233(3)
7.4, –6.4
1.—
1
1
1
1
d
e
1.212(5)
1.218(3)
1.238(4),
1.486(4)
1.9
8.7
6.8, 17.4,
–1.9, 7.0
1.771(3)
1.—
1.—
1.375(4),
1.371(4),
1.369(4),
1.381(4)
1.4919(19)
1.481(5),
1.487(5),
1.3694(17)
1.365(4),
1.369(4),
1.362(3),
1.360(4)
g•0.5MeCN
1
.228(4)
1
1
.486(4),
.481(4)
*
at 200 K, P21.
*
* at 240 K, C2221.

2
,5ꢀDibenzylidencyclopentanones
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
1765
though these bonds are arranged not parallel to each other.
The compound 1a was found to undergo the solidꢀphase
PCA reaction with the formation of a cyclobutane derivaꢀ
tive, which corresponds to the topology of the dimeric pair
2
7
of the starting molecules in crystal.
The structure of crystal 1g•0.5MeCN differs from others,
probably, because of the inclusion of an acetonitrile moleꢀ
cule, which forms a C=O(3´)...H C(2S)CN contact with
3
one of the independent molecule of 1g (d(O...H) =
=
2.25 Å). Here, the closest C=C bonds are remote from
each other by a distance of 4.51—4.70 Å and are arranged
crossꢀlike, that is unfavorable for PCA.
For compound 1a, a reversible phase transition is obꢀ
served in the region of 220—230 K (lowꢀtemperature monꢀ
oclinic P2 ↔ highꢀtemperature orthorhombic C222 ). In
1
1
Fig. 3. Intermolecular contacts in crystals 1b, 1b•CHCl , 1d,
and 1e.
the structure of the highꢀtemperature phase, the molecule
is located on the second order axis, passing through the C
and O atoms of the carbonyl group. In the structure of the
lowꢀtemperature phase, the molecule occupies a general
position. A decrease in temperature leads to the appearꢀ
ance of considerable differences in the C(O)—C (>0.03 Å)
and CH—Ph bond distances (>0.05 Å). However, no conꢀ
siderable conformational changes are observed in the molꢀ
ecule: the central fiveꢀmembered ring virtually retains its
planarity and the angles of turning of the phenyl substituꢀ
ents almost do not change. It should be noted that the
structures of 1a at 200 and 220 K can be refined in the
3
one of the independent molecules of 1g this angle is equal
to 17.4°, that, however, does not interfere with the effiꢀ
cient conjugation over the entire chromophore. In generꢀ
al, the bond distances and bond angles are close to comꢀ
mon values for conjugated ketones.
In crystals 1b, 1b•CHCl , 1d, and 1e, directed or bifurꢀ
3
cated shortened contacts C=O...H C—CH between
2
2
the neighboring molecules are observed (d(O...H) =
2.46—2.69 Å), which leads to the formation of chained
=
orthorhombic group C222 , but this leads to more than
1
structures with hydrogen bonding (Fig. 3). In these strucꢀ
tures, the C=C bonds of the neighboring molecules are
not parallel and are considerably remote from each other,
twoꢀfold increase in the final R factor and appearance of
1
the abnormal values for thermal ellipsoids in all the atoms
of the phenyl rings.
Differential scanning calorimetry (DSC) was used to find
out the phase transition temperatures of compound 1a. The
most informative part of the thermogram of this compound
upon heating in the thermocycling regime is given on Fig. 5.
30
that, according to topochemical criteria, is unfavorable
for the PCA reaction to occur in the solid phase.
In the structure of compound 1a (a highꢀtemperature
phase), the topology of these contacts is somewhat differꢀ
ent and leads to the formation of hydrogenꢀbonded layers
(
Fig. 4). We also observed such layers for 2,5ꢀbis(4ꢀ
1
2
pyridylmethylidene)cyclopentanone. In such packings,
the C=C double bonds of neighboring molecules approach
each other in the parallel planes to a distance less than 4 Å,
DSC/mW mg–1
1
95 °С
4
2
0
2
4
6
8
1
87 °С
1
3
2
–
–
–
–
1
46 °С
–
10
1
20 130 140 150 160 170 180 190 200 T/°С
Fig. 5. The results of analysis by DSC of the sample 1a: the first
heating (1), cooling (2), repeated heating (3).
Note. Figures 5 and 6 are available in full color on the web page
of the journal (http://www.link.springer.com).
Fig. 4. Intermolecular contacts in crystal 1a.

1
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Vatsadze et al.
DSC/mW mg–1
ally characteristic of the processes on metallic electrodes.31
Therefore, in the present publication we discuss the results
obtained on more inert GC electrode, since the values of
potentials recorded on both electrode are close to each other.
Preliminary experiments showed that the cathodic
peaks of all the dienones under study are electrochemicalꢀ
ly irreversible and correspond to the transfer of one elecꢀ
tron. For the twoꢀstep reduction of dienones 1a, 1b, 1d,
and 1e, the following sequence of steps can be suggested.
The electron transferring on the conjugated system of
0
0
0
0
.20
.15
.10
.05
0
0.05
0.10
0.15
1
2
–
–
–
–
150 –100 –50
0
50
100 T/°С
Fig. 6. DSC curves of the sample 1a upon heating (1) and coolꢀ
ing (2) in the region of low temperatures. Glassꢀtransition paraꢀ
meters upon heating: beginning –20.62 °C; middle –20.93 °C;
πꢀbonds of the substrate (at E ) is mostly localized on the
1
oxygen atom of the carbonyl group. The forming radical
anion either dimerizes, or undergoes protonation (the
ECEꢀmechanism) with the formation of a free radical,
inflection point –21.01 °C; end –21.23 °C; change C
p*
–
1
0
–
.066 J (g K) ; upon cooling: beginning –42.31 °C; middle
which, as a rule, undergoes reduction at the E of the
38.55 °C; inflection point –41.97 °C; end –50.98 °C; change
1
–
1
Cp* 0.107 J (g K)
.
substrate (with either the supporting electrolyte, or the
3
2—34
solvent serving as proton donors
).
The range of differences of potentials of the first cathꢀ
odic peaks of dienones 1b—g is quite wide (20—270 mV)
as compared to unsubstituted dienone 1a. The donor inꢀ
fluence of alkoxy and dimethylamino groups on the values
of cathodic potentials is comparable between each other:
the potentials shift to the cathodic region by 130 and 120 mV,
respectively. The influence of the methylthio group is conꢀ
siderably lower (around 20 mV). The presence of the second
alkoxy group at metaꢀposition in compounds 1f and 1g
virtually does not affect the values of potentials of the first
step of reduction, probably, due to the absence of conjugaꢀ
tion with the carbonyl group.
Compound 1a was found to demonstrate high stability
of the structure upon heating up to the melting point
195 °C), that is reflected in the absence of changes in the
(
form of heating (cooling) curves. The difference in the
values of its melting point and crystallization temperature
by the DSC data is explained by kinetic specificities of the
method used, in particular, by both "overcooling" of the
melt and possible insignificant degradation. This is indicated
by the form of the DSC curves in the second heating.
The studies of thermal properties of compound 1a in
the region of negative temperatures showed the presence
–
1
of insignificant thermal effect (ΔCp* = 0.107 J (g K) ),
The influence of substituents on electrooxidation of
dienones 1b—g turned out to be more noticeable as comꢀ
which was observed in the 230—222 K temperature range
(
Fig. 6).
This effect can be explained by glass transition or other
Table 2. Electrochemical potentials of compounds 1a—g in
MeCN measured relative to Ag/AgCl/KCl(sat.) by CVA in the
presence of 0.1 M Bu NClO on GCꢀelectrode, the potential
structural rearrangement of crystals, that is in good agreeꢀ
ment with the data on phase transition obtained by Xꢀray
diffraction.
4
–1
4
sweep speed 200 mV s
To establish the influence of substituents in the aroꢀ
matic rings of crossꢀconjugated dienones on the energy of
frontier orbitals of molecules, compounds 1a—g were studꢀ
ied by cyclic voltammetry (CVA) on a purified surface of
glassy carbon (GC) or Pt electrodes in solutions of MeCN
and DMF (Fig. 7, Table 2). The CVAꢀcurves were recordꢀ
ed from 0 V to the cathodic or anodic region of potentials.
Table 2 contains the data on peak potentials obtained
in a solution of MeCN, in order to compare electrochemꢀ
ical parameters with the data of other physicochemical
methods of study carried out in the same solvent. The
Table also contains the values of differences of reduction
and oxidation potentials of the substrates as compared to
unsubstituted compound 1a. Despite the lower solubility
of compounds 1b—g in MeCN as compared to DMF, we
preferred to use the former as the solvent. In turn, recordꢀ
ing of the CVAꢀcurves on Pt electrode showed that for
some compounds (see Fig. 7, d), it contains an adsorption
prepeak in the potentials region –0.6+0.9 V, that is generꢀ
Comꢀ
pound
Ered/V ΔEred
*
E /V
ΔE ** ΔE = Eox –Ered
ox
ox
/mV
/mV
/V
1
1
a
b
–1.26,
1.87
–1.38,
1.71
000
1.92
0000
3.18
—
120
270
0.93
1.04/0.94
0999
1110
2.31
–
1
.34/1.24
0.81
.94/0.84
.20/1.24
1.50
1
c
–1.53
2. 34
0
1
1d
–1.24,
–1.86
–1.39,
–20
130
0420
0440
2.74
2.87
1
e
1.48
–
1.94
1
1
f
g
–1.38,
–1.38
120
120
1.35
1.36
0570
0560
2.73
2.74
* Shift of reduction potential relative to 1a.
** Shift of oxidation potential relative to 1a.

2
,5ꢀDibenzylidencyclopentanones
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
1767
I/mA
a
I/mA
b
0
0
0
.06
.04
.02
0
0.12
0.08
0.04
0
–
0.02
–0.04
–
2000 –1000
0
1000
2000 E/mV
–2000 –1000
I/mA
0
1000 2000 3000 E/mV
I/mA
c
d
0
0
0
0
0
.10
0
0
.02
.08
.06
.04
.02
0
.01
0
–
0.01
–
1000
0
1000
2000
3000 E/mV
–1000
0
1000
2000 E/mV
Fig. 7. Cyclic currentꢀpotential curves of dienones: (a) 1d in DMF (solid line) and in MeCN (dashed line) on GCꢀelectrode, (b) 1a in
MeCN on GCꢀelectrode, (c) 1a (solid line), 1b (dashed line), and 1c (dotted line) in MeCN on Pt electrode, (d) 1c in MeCN on GCꢀ
(
dashed line) and Pt electrodes (solid line).
pared to unsubstituted 1a. The shifts of potentials to the less
anodic region were 440—1110 mV (Table 2, Fig. 7, c).
The most significant shift was observed in the case of diꢀ
enones 1b and 1c containing dimethyl and diethylamino
groups as substituents, the values of oxidation potentials
of which are close to the corresponding values of amines
Table 3. Parameters of electron absorption (λabs (ε)) and fluoresꢀ
cence spectra of dienones (λ ) 1a—g in MeCN
fl
Compound
λabs (ε)
λfl/nm
/nm (L mol– cm–1
1
)
3
5
(
0.8—1.1 V). Such a considerable difference of anodic
potentials in substituted dienones 1b—g as compared to
unsubstituted dienone 1a indicates that the HOMO is
mostly localized on the donor substituents of the conjuꢀ
gated πꢀsystem. The oxidation of dialkoxy derivatives of
dienones 1f and 1g with one alkoxy group at metaꢀposition
not conjugated with the carbonyl group proceeds easier
only by 120 mV, than that of monosubstituted alkoxy
derivative.
1
1b
a
345 (37900), 231 (12000)
458 (64300), 378 (18300),
330 (6900), 269 (18500)
471 (64600), 276 (16400)
380 (43000), 242 (15100)
—
562
1c
562
508
—
500
500
1
1
1
1
d
e
f
396 (35100), 258 (11600)
395 (38900), 268 (9300), 253 (11600)
395 (35300), 268 (9300), 253 (11200)
g

1
768
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
Vatsadze et al.
D
existence of a linear dependence between electrochemical
and spectrophotometric characteristics of dienone moleꢀ
cules.
0
.7
.6
.5
.4
.3
.2
.1
1
b
1c
37—39
0
0
0
0
0
0
To establish a relationship between the data of absorpꢀ
tion spectra and the electrochemical parameters, as well
as the presence of the dependence of such results on the
electronic properties of substituents in the benzene rings
of dienones 1a—g, we carried out a correlation analysis of
the following dependences: 1) between the oxidation/reꢀ
duction potential differences and the LAB maximum
energy; 2) the difference between the calculated HOMO/
LUMO energies and the LAB maximum energy; 3) energy
of HOMO and the oxidation potential values; 4) energy of
LUMO and the reduction potential values; 5) between the
sigma constants of substituents and the LAB maximum
energy. The most acceptable results were obtained for deꢀ
pendences (1) (Fig. 9) (with the correlation coefficient
of 0.9343) and (2) (with the correlation coefficient of
1
1
g 1d
a
1
f
1e
3
00
400
500
600 λ/nm
Fig. 8. Absorption spectra of dienones 1a—g in MeCN, C =
–
5
–1
=
1•10 mol L .
–
0.8620).
To establish the influence of substituents polarity
These results allow us to state that in the series of
on spectral properties of dienones 1a—f, we recorded
related compounds, for example, for crossꢀconjugated
dienones, despite the irreversibility of the electrochemical
reduction step, the energy characteristics of frontier orbitꢀ
als can be adequately described by both the electrochemiꢀ
cal and the spectrophotometric data. The dependences
obtained in this work can be used in the analysis of other
dienone compounds and obtaining necessary characterisꢀ
tics of new molecules.
Since the Xꢀray diffraction data showed unfavorable
orientation of the double bonds in dienones 1a, 1b, 1d,
and 1e for the PCA to take place, we decided to check
a possibility of photochemical transformations for powꢀ
ders of 1c and 1f, the crystal structures of which were not
known to us. The samples were exposed to the light of an
incandescant lamp during 5 h, which is usually enough for
the reaction to proceed at least by 10%. Analysis by NMR
their electronic absorption and fluorescence spectra
(Table 3, Fig. 8).
All the dienones have a strong longꢀwavelength absorpꢀ
tion band (LAB) with λmax from 345 nm (for 1a) to 471 nm
for 1c) and additionally several bands in more shortꢀwaveꢀ
length region of the spectrum. The LAB can be assigned to
(
2
5,26
transitions of the type HOMO—LUMO,
the shortꢀ
wavelength bands to the local electron transitions in the
aromatic rings. It is worthy to note a qualitative depenꢀ
dence of the LAB maxima on the donor ability of substituꢀ
ents at paraꢀposition of the benzylidene fragments. Thus,
the LAB of paraꢀdialkylaminoꢀsubstituted 1b,c are shifted
the most to the red region relative to that of unsubstituted
1
a, which is in good agreement with the high electronꢀ
donating character of the substituents and correlates with
the lowest oxidation potentials in the series of compounds
under consideration (see Table 2). The LAB maxima of
metaꢀalkoxyꢀsubstituted compounds 1f and 1g are shifted
to 395—396 nm, whereas the oxidation potentials are inꢀ
creased as compared to those of 1b and 1c. In dienone 1d,
the SMe substituents are even less electronꢀdonating, that
expectedly leads to further shortꢀwavelength shift of the
LAB maximum and increase in the Eox value.
spectroscopy in MeCNꢀd showed the absence of photoꢀ
3
reaction products, that can be explained by the absence of
favorable orientations of the double bonds in dienones for
ΔE/V
3
3
.4
.2
The dependence of the fluorescent properties of comꢀ
pounds 1a—g on their oxidation potentials is in general
1
a
3.0
2.8
1e
similar to the dependence λmax(LAB)—E . Amino derivꢀ
ox
atives 1b and 1c are characterized by the most bright, as
well as the most longꢀwavelength fluorescence (see Table 3,
Fig. 8). Specifics of absorption and emission of compound
2
2
.6
.4
1f,g 1f
1
c
1
c and its azacrown ether analog are described in our reꢀ
2.2
1b
3
6
cent work.
Earlier, we carried out the studies of a number of deꢀ
pendences of calculated and experimental characteristics
of a wide range of Nꢀdonor ligands, including some
pyridineꢀcontaining dienones. Among other, we found an
680
730
780
830
880 ν/THz
Fig. 9. Correlation dependence between the energy of longꢀ
wavelength absorption maximum and the difference of oxidaꢀ
tion/reduction potentials (ΔE) for dienones 1a—g.

2
,5ꢀDibenzylidencyclopentanones
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
1769
the potential sweep speed was 200 mV s–1, the potentials are
given with allowance for iRꢀcompensation. The number of transꢀ
ferred electrons was determined by a comparison of the value of
current peak in substrate and the current of oneꢀelectron oxidaꢀ
tion of ferrocene taken in equal concentrations.
the PCA to take place in the solid phase. In solution, the
product of such transformation was observed only in the
NMR spectra of cyclopentanone 1a (~10%, both in the
presence of CCl COOH and without the acid) after the
3
exposure of the sample to the ambient light. The appearꢀ
ance in the solution of characteristic signals, viz., a singlet
of the cyclobutane protons at δ 4.43 and a multiplet of
cyclopentanone protons in the region of δ 2.5, agrees with
the data obtained by us earlier for the PCA products: in the
The temperatures of compound phase transitions were deꢀ
termined by DSC. The studies were carried out on a Netzsch
DSC 204 F1 Phoenix automated differential calorimeter
(GERMANY) in the temperature range from –180 to 700 °C at
–
1
the rate of heating and cooling of the sample of 5 deg min . The
studies were carried out under nitrogen, the weight of the test
sample was 100 mg. In the experiment, the compound herꢀ
metized in an aluminum crucible with a hole in the cap for
a possibility to remove gaseous decomposition products. The
crucible on a sample holder was cooled by a controlled automatꢀ
ed supply with liquid nitrogen.
1
2
case of 3ꢀpyridylꢀsubstituted analog of dienones 1a—g
and product of dimerization of 1a.1 Probably, the presꢀ
5
ence of acceptor aryl substituents in the aromatic rings is
necessary for the PCA reaction to proceed without suꢀ
pramolecular preorganization. In the case of compounds
1
b—g bearing donor substituents and their crown ether
All the measurements were carried out under anhydrous
argon. The samples were dissolved in a preꢀdeaerated anhydrous
solvent, using MeCN of "for electrochemistry" grade (Sigmaꢀ
Aldrich). DMF (pure grade) was purified by stirring over freshly
calcined K2CO3 for four days and subsequent distillation in vacuo
first over P O and then over anhydrous CuSO .
analogs, supramolecular templates should be used for the
PCA reaction to take place.
In conclusion, the obtained results allow us to state
that the condensation products of cyclopentanone with
benzaldehyde derivatives are characterized by the E,Eꢀ
configuration. Molecules of five model dienones in the
crystalline state are arranged unfavorably for the PCA to
occur, which confirms the idea about the necessity of suꢀ
pramolecular preorganization of the double bonds to unꢀ
dergo such a transformation. The found dependences of
the redox potentials on the position, the nature, and the
number of substituents in the benzene ring, as well as their
correlation with photophyical characteristics, are of unꢀ
doubted interest for future studies of the dienone crown
ether derivatives.
2
5
4
Xꢀray diffraction experiments were performed on Bruker
SMART APEX II, Xcalibur Gemini ultra, and Bruker D8 Venꢀ
ture automated diffractometers, using MoꢀKα and CuꢀKα radiꢀ
ation (λ = 0.71073 and 1.54178 Å, respectively, graphite monoꢀ
chromator, ωꢀscan technique). Correction for adsorption was
introduced using measurements of intensities of equivalent reꢀ
4
0
flections. The structures were solved by direct method and
2
refined in the fullꢀmatrix anisotropic least squares method on F
4
1
for all the nonhydrogen atoms. In the structures 1b•CHCl3
and 1e, all the hydrogen atoms were found from the difference
Fourier synthesis and refined isotropically, whereas in all the
other cases hydrogen atoms were placed in calculated positions
and refined using a riding scheme. The crystal of 1a (200 and
Experimental
2
20 K) was found to be a pseudomerohedral twin with a twinning
matrix 1 0 0, 0 –1 0, –1 0 –1 and approximately equal ratio of
domains. The results of the Xꢀray diffraction studies are given in
Tables 4 and 5.
1H and 13C NMR spectra were recorded on Bruker Avanceꢀ400
and Agilent 400ꢀMR spectrometers (at 400 and 100 MHz, reꢀ
spectively) in CDCl at 23 °C. Chemical shifts were measured
The Xꢀray diffraction studies were performed in the Multiꢀ
access Center of the N. S. Kurnakov Institute of General and
Inorganic Chemistry, Russian Academy of Sciences. The strucꢀ
tural data were deposited with the Cambridge Crystallographic
Data Center (CCDC: 1440169 (1a, 150 K), 1440170 (1a, 200 K),
1440171 (1a, 220 K), 1440172 (1a, 230 K), 1440173 (1a, 240 K),
3
relative to TMS (δ ) and CDCl (δ 77). Chemical shifts were
H
3
C
measured with the accuracy of 0.01 ppm, spinꢀspin coupling
constant were measured with the accuracy of 0.1 Hz. Elemental
analysis of synthesized compounds was performed on a Vario
microcube CHNꢀanalyzer. IR spectra were recorded on a URꢀ20
spectrophotometer in Nujol. Electron absorption spectra were
recorded on a Cary 4000 spectrophotometer in MeCN, in the
case of experiments with acids on a Specord Mꢀ40 spectrophotoꢀ
meter in ethanol. Fluorescence spectra were recorded on a Cary
Eclipse spectrofluorimeter at ~20 °C. Reaction progress was
monitored by thinꢀlayer chromatography, using Silufol UVꢀ254
precoated plates.
1440174 (1b•CHCl ), 1440175 (1d), 1440176 (1e), 1446525 (1b)
3
and 1446526 (1g•0.5MeCN).
Synthesis of cyclopentanone 2,5ꢀdibenzylidene derivatives
(1a—e) (general procedure). Ethanol (25 mL) was added to
a solution of NaOH (40 mg, 1 mmol) in water (1 mL) with
vigorous stirring, followed by the addition of benzaldehyde
(10 mmol) and a dropwise addition of cyclopentanone (440 μL,
5 mmol) in EtOH (3 mL). The mixture was stirred for 48 h.
Electrochemical studies were carried out on a IPCꢀPro M
potentiostat. The measurements were carried out following
a threeꢀelectrode scheme. Glassy carbon (d = 2 mm) and platiꢀ
num (d = 3 mm) disks served as working electrodes, supporting
electrolyte was a 0.1 M solution of Bu NClO in DMF or MeCN,
Then, the thickened mixture was diluted with Et O (30 mL) and
2
stirred for 30 min. A precipitate formed was collected by filtraꢀ
tion, then resuspended in Et O, again collected by filtration, and
2
dried in air.
4
4
Ag/AgCl/KCl(aqueous, sat.) served as a reference electrode,
platinum plate as an auxiliary electrode. The surface of working
electrodes was polished with alumina powder with the particle
size no less than 10 μm (SigmaꢀAldrich). In the studies by CVA,
(2E,5E)ꢀ2,5ꢀDibenzylidenecyclopentanone (1a). A pale yelꢀ
low crystalline powder. The yield was 93%, m.p. 196—198 °C
1
(cf. Ref. 12: 196 °C). H NMR, δ: 3.12 (s, 4 H, CH CH ); 7.36—7.46
2
2
(m, 6 H, 2 H(3´), 2 H(4´), 2 H(5´)); 7.60 (m, 6 H, 2 H(2´),

1
770
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
Vatsadze et al.
1g•0.5MeCN
Table 4. Parameters of crystals and Xꢀray diffraction studies for compounds 1b, 1b•CHCl , 1d, 1e, and 1g•0.5MeCN
3
Parameter
1b
1b•CHCl3
1d
1e
Molecular formula
Molecular weight
Crystal size/mm
Crystal system
Space group
Т/K
C23H26N O
C24H27Cl N O
C H20OS2
352.49
C H20O3
320.37
C26H29.5N0.5O5
429.00
2
3
2
21
21
346.46
465.83
0.22×0.08×0.01 0.32×0.06×0.02 0.25×0.20×0.01 0.35×0.30×0.05 0.27×0.20×0.06
Orthorhombic
Orthorhombic
Fdd2
Orthorhombic
Pnma
Orthorhombic
Cmc21
Monoclinic
Cc
P2 2 2
1 1
1
120
150
120
150
120
a/Å
b/Å
c/Å
β/deg
5.8397(12)
7.8165(16)
39.872(7)
90
33.382(2)
45.814(3)
5.9663(4)
90
5.9835(8)
40.775(6)
7.0689(10)
90
36.795(4)
7.1556(8)
6.2162(7)
90
7.8121(3)
18.8257(10)
30.3932(12)
90.273(4)
4469.8(3)
3
V/Å
1820.0(6)
9124.7(10)
1724.6(4)
1636.7(3)
Z
4
16
4
4
8
–
3
dcalc/g cm
μ/mm
F(000)
1.264
0.601
744
1.356
0.421
3904
1.358
0.313
744
1.300
0.086
680
1.275
0.088
1832
–
1
Range of scanning on θ/deg
4.44—76.23
11437
3546 (0.2710)
1297
2.16—27.00
21741
4982 (0.0564)
3845
2.92—25.05
9788
1546 (0.0968)
1048
2.21—30.00
9130
1319 (0.0265)
1261
2.55—29.00
23767
11385 (0.0891)
6626
Number of measured reflections
Number of independent reflections (Rint
Number of reflections with I ≥ 2σ(I)
Number of refinement parameters
)
239
379
113
152
577
R (I ≥ 2σ(I))
0.1158
0.0447
0.0559
0.0379
0.0696
1
wR (on all the reflections)
Reliability on F
0.3251
0.957
0.1007
1.020
0.1065
1.119
0.0995
1.036
0.1065
0.928
2
2
Residual electron density
0.460/–0.368
0.479/–0.583
0.293/–0.342
0.453/–0.194
0.312/–0.259
–
3
(
max/min)/e Å
1
2
2
H(6´), 2 CHPh). 13C NMR, δ: 26.51 (CH CH ); 128.74 (2 C(3´),
C(5´)); 129.35 (2 C(4´)); 130.71 (2 C(2´), 2 C(6´)); 133.82
H NMR, δ: 2.52 (s, 6 H, 2 MeS); 3.09 (s, 4 H, CH CH ); 7.28
2 2
2
2
3
(d, 4 H, 2 H(3´), 2 H(5´), J = 8.5 Hz); 7.52 (d, 4 H, 2 H(2´),
2 H(6´), J = 8.5 Hz); 7.54 (s, 2 H, 2 CHAr). C NMR, δ: 15.13
(2 MeS); 26.55 (CH CH ); 125.87 (2 C(3´), 2 C(5´)); 131.08
(2 C(2´), 2 C(6´)); 132.39 (2 C(1´)); 133.22 (2 CHAr); 136.58 (C(2),
C(5)); 141.04 (2 C(4´)); 196.08 (C=O). Found (%): C, 79.85;
H, 7.13; N, 7.65. C H ON . Calculated (%): C, 79.73; H, 7.56;
3
13
(
2 CHPh); 135.79 (C(2), C(5)); 137.27 (2 C(1´)); 196.35 (C=O).
Found (%): C, 87.22; H, 6.29. C H O . Calculated (%):
C, 87.66; H, 6.19. IR, ν/cm–1: 1700 (C=O), 1630 (C=C).
2E,5E)ꢀ2,5ꢀBis[4ꢀ(dimethylamino)benzylidene]cyclopentanꢀ
one (1b). A dark yellow crystalline powder. The yield was 73%,
m.p. 298 °C (cf. Ref. 43: >300 °C and cf. Ref. 12: 298 °C). H NMR,
1
9
16
5
2
2
(
2
3
26
2
1
–1
N, 8.09. IR, ν/cm : 1700 (C=O), 1615 (C=C).
δ:* 3.03 (s, 12 H, 2 Me N); 3.06 (s, 4 H, CH CH ); 6.73 (d, 4 H,
(2E,5E)ꢀ2,5ꢀBis(4ꢀmethoxybenzylidene)cyclopentanone (1e).
A yellow crystalline powder. The yield was 93%, m.p. 198 °C
2
2
2
3
2
2
4
1
1
H(3´), 2 H(5´), J = 8.9 Hz); 7.52 (s, 2 H, 2 CHAr); 7.53 (d, 4 H,
3
13
1
H(2´), 2 H(6´), J = 8.9 Hz). C NMR, δ: 26.64 (CH CH );
(cf. Ref. 12: 198 °C). H NMR, δ: 3.08 (s, 4 H, CH CH ); 3.86
2
2
2
2
3
0.12 (2 Me N); 111.87 (2 C(3´), 2 C(5´)); 124.25 (2 C(1´));
(s, 6 H, 2 MeO); 6.96 (d, 4 H, 2 H(3´), 2 H(5´), J = 8.8 Hz);
2
3
32.53 (2 C(2´); 2 C(6´)); 133.48 (C(2), C(5)); 133.51 (2 CHAr);
50.71 (2 C(4´)); 196.03 (C=O). Found (%): C, 79.85; H, 7.13;
7.56 (s, 2 H, 2 CHAr); 7.57 (d, 4 H, 2 H(2´), 2 H(6´), J = 8.8 Hz).
13
C NMR, δ: 26.45 (CH CH ); 55.36 (2 MeO); 114.28 (2 C(3´),
2
2
N, 7.65. C H ON . Calculated (%): C, 79.73; H, 7.56; N, 8.09.
2 C(5´)); 128.77 (2 C(1´)); 132.49 (2 C(2´), 2 C(6´)); 133.26
(2 CHAr); 135.28 (C(2), C(5)); 160.51 (2 C(4´)); 196.25 (C=O).
Found (%): C, 78.85; H, 6.13. C H O . Calculated (%): C, 78.73;
2
3
26
2
–
1
IR, ν/cm : 1680 (C=O), 1610 (C=C).
2E,5E)ꢀ2,5ꢀBis[4ꢀ(diethylamino)benzylidene]cyclopentanꢀ
one (1c). A dark yellow fine crystalline powder, m.p. 183—185 °C
(
2
1
20
3
H, 6.29. IR, ν/cm– : 1700 (C=O), 1600 (C=C).
1
1
3
(
cf. Ref. 44: 169 °C). H NMR, δ: 1.20 (t, 12 H, 4 Me, J = 7.1 Hz);
(2E,5E)ꢀ2,5ꢀBis(3,4ꢀdimethoxybenzylidene)cyclopentanone
(1f). Veratric aldehyde (166 mg, 1 mmol) was added to a solution
of cyclopentanone (44 μL, 0.5 mmol) in 75% aqueous EtOH
(5 mL). Then, a solution of NaOH (20 mg, 0.5 mmol) in water
(0.3 mL) was added to the obtained solution with vigorous stirꢀ
ring. The reaction mixture was stirred for 2 h. A yellow precipiꢀ
tate formed was collected by filtration, washed with water and
3
3
6
2
.06 (s, 4 H, CH CH ); 3.41 (q, 8 H, 4 CH Me, J = 7.1 Hz);
2 2 2
.69 (d, 4 H, 2 H(3´), 2 H(5´), J = 8.9 Hz); 7.50 (d, 4 H,
H(2´), 2 H(6´), J = 8.9 Hz); 7.51 (s, 2 H, 2 CHAr). C NMR,
3
3
13
δ: 12.64 (4 Me); 26.68 (CH CH ); 44.44 (4 CH Me); 111.34 (2 C(3´),
2
2
2
2
(
C(5´)); 123.53 (2 C(1´)); 132.82 (2 C(2´), 2 C(6´)); 133.08
C(2), C(5)); 133.43 (2 CHAr); 148.29 (2 C(4´)); 195.94 (C=O).
2E,5E)ꢀ2,5ꢀBis[4ꢀ(methylthio)benzylidene]cyclopentanone
1d). A yellow crystalline powder. The yield was 92%, m.p. 226 °C.
(
Et O, dried in air. The yield was 78%, m.p. 195—197 °C (cf. Ref. 44:
2
1
(
188—190 °C). H NMR, δ: 3.08 (s, 4 H, CH CH ); 3.90 (s, 12 H,
3´ꢀMeO, 2 4´ꢀMeO); 6.91 (d, 2 H, 2 H(5´), J = 8.5 Hz); 7.10
(d, 2 H, 2 H(2´), J = 1.6 Hz); 7.20 (dd, 2 H, 2 H(6´), J = 8.5 Hz,
J = 1.6 Hz); 7.51 (s, 2 H, 2 CHAr). C NMR, δ: 26.41
2
2
3
2
In the previous publication,12 for technical reasons the proton
spectra for compounds 1b and 1d were given incorrectly.
4
3
*
4
13

2
,5ꢀDibenzylidencyclopentanones
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 7, July, 2016
1771
Table 5. Details of multitemperature Xꢀray diffraction studies of compound 1a
Parameter
Temperature/К
220
1
50
200
230
240
Molecular formula
C H O
1
9
16
Molecular weight
Crystal size/mm
Crystal system
Space group
a/Å
260.32
0.45×0.30×0.12
Monoclinic
P21
0.25×0.12×0.08
Monoclinic
P21
5.516(6)
20.80(2)
6.232(6)
111.422(14)
665.8(12)
2
0.25×0.12×0.08
Monoclinic
P21
0.45×0.30×0.12
Orthorhombic Orthorhombic
C2221
11.806(9)
5.665(4)
20.846(15)
90
C2221
11.811(3)
5.6757(16)
20.805(6)
90
5.614(8)
21.06(3)
6.423(9)
113.46(3)
696.8(16)
2
1.241
0.075
276
5.623(9)
20.90(3)
6.488(11)
114.78(4)
692(2)
b/Å
c/Å
β/deg
V/Å3
Z
dcalc/g cm
μ/mm
F(000)
1394.2(17)
4
1394.6(7)
4
2
–
3
1.299
0.078
276
1.249
0.075
276
1.240
1.240
–
1
0.075
0.075
552
552
Number of measured reflections
4531
5946
6079
6241
6473
Number of independent reflections (Rint
Number of reflections with I ≥ 2σ(I)
Number of refinement parameters
)
1451 (0.0872)
1094
1720 (0.1109)
896
1709 (0.1026)
940
989 (0.0856)
649
987 (0.0494)
725
181
182
182
92
123
R (I ≥ 2σ(I))
0.1086
0.3251
1.118
0.0788
0.2422
0.939
0.0765
0.2523
0.879
0.0935
0.2866
1.813
0.0559
0.1498
1.113
1
wR (on all the reflections)
2
2
Reliability on F
Residual electron density
0.737/–0.432
0.256/–0.272
0.236/–0.241
0.192/–0.383
0.175/–0.182
(
max/min)/e Å–3
(
1
CH CH ); 55.86, 55.93 (2 3´ꢀMeO, 2 4´ꢀMeO); 111.17 (2 C(5´));
13.47 (2 C(2´)), 124.53 (2 C(6´)), 128.99 (2 C(1´)); 133.60
References
2
2
(
1
2 CHAr); 135.35 (C(2), C(5)); 148.91, 150.26 (2 C(3´), 2 C(4´));
95.92 (C=O). Found (%): C, 72.57; H, 6.29. C H O . Calcuꢀ
1
. V. P. Ananikov, L. L. Khemchyan, Yu. V. Ivanova, V. I.
Bukhtiyarov, A. M. Sorokin, I. P. Prosvirin, S. Z. Vatsadze,
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Likholobov, A. V. Romanenko, P. A. Simonov, V. G.
Nenajdenko, O. I. Shmatova, V. M. Muzalevskiy, M. S.
Nechaev, A. F. Asachenko, O. S. Morozov, P. B. Dzhevakov,
S. N. Osipov, D. V. Vorobyeva, M. A. Topchiy, M. A. Zotova,
S. A. Ponomarenko, O. V. Borshchev, Yu. N. Luponosov,
A. A. Rempel, A. A. Valeeva, A. Yu. Stakheev, O. V. Turova,
I. S. Mashkovsky, S. V. Sysolyatin, V. V. Malykhin, G. A.
Bukhtiyarova, A. O. Terent´ev, I. B. Krylov, Russ. Chem.
Rev., 2014, 83, 885.
2
3
24
5
–
1
lated (%): C, 72.63; H, 6.32. IR (KBr), ν/cm : 1680 (C=O).
2E,5E)ꢀ2,5ꢀBis(3ꢀethoxyꢀ4ꢀmethoxybenzylidene)cyclopentꢀ
anone (1g). 3ꢀEthoxyꢀ4ꢀmethoxybenzaldehyde (216 mg, 1.2 mmol)
was added to a solution of cyclopentanone (53 μL, 0.6 mmol) in
(
7
5% EtOH (7 mL). Then, a solution of NaOH (20 mg, 0.5 mmol)
in water (0.3 mL) was added to the obtained solution with vigorꢀ
ous stirring. The reaction mixture was stirred for 2 h. A yellow
precipitate formed was collected by filtration, washed with water
and Et O, dried in air. The yield was 83%, m.p. 198—199 °C.
1
2
3
H NMR, δ: 1.48 (t, 6 H, 2 MeCH , J = 7.0 Hz); 3.08 (s, 4 H,
2
CH CH ); 3.90 (s, 6 H, 2 MeO); 4.13 (q, 4 H, 2 CH Me,
3
2
2
2
3
J = 7.0 Hz); 6.92 (d, 2 H, 2 H(5´), J = 8.4 Hz); 7.12 (d, 2 H,
H(2´), J = 1.9 Hz); 7.20 (dd, 2 H, 2 H(6´), J = 8.4 Hz,
J = 1.9 Hz); 7.51 (s, 2 H, 2 CHAr). C NMR, δ: 14.77 (2 MeCH );
2
3
. Organic Reactions, vol. 10, Ed. R. Adams, Wiley, 1959, 576.
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4
3
2
4
13
2
2
(
1
2
6.45 (CH CH ); 55.99 (2 MeO); 64.42 (2 CH Me); 111.42
2
2
2
4. J. Cui, D. Crich, D. Wink, M. Lam, A.L. Rheingold, D. A.
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2 C(5´)); 114.99 (2 C(2´)); 124.56 (2 C(6´)); 128.98 (2 C(1´));
33.69 (2 CHAr); 135.31 (C(2), C(5)); 148.23, 150.62 (2 C(3´),
C(4´)); 196.01 (C=O). Found (%): C, 73.47; H, 6.79. C H O .
2
5
28
5
5. M. M. Gar, O. N. Arkhipova, S. V. Popkov, Agrokhimiya
–
1
Calculated (%): C, 73.53; H, 6.86. IR (KBr), ν/cm : 1680
C=O).
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Received December 8, 2015;
in revised form April 14, 2016