Halogenation of N-substituted p-quinone monoimines and p-quinone monooxime ethers: XV. Synthesis and bromination of 4-(cinnamoyloxyimino)-cyclohexa-2,5-dienones

Article abstract of DOI:10.1134/S1070428016070034

New 4-(cinnamoyloxyimino)cyclohexa-2,5-dien-1-ones were synthesized, and their bromination afforded bromine addition products to the syn- and anti-C=C bonds of the quinoid ring. In all cases, bromine addition to the C=C double bond of the cinnamoyl fragme

Full text of DOI:10.1134/S1070428016070034

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2016, Vol. 52, No. 7, pp. 939–945. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © S.A. Konovalova, A.P. Avdeenko, S.A. Goncharova, 2016, published in Zhurnal Organicheskoi Khimii, 2016, Vol. 52, No. 7,
pp. 947–953.
Halogenation of N-Substituted p-Quinone Monoimines
and p-Quinone Monooxime Ethers:
XV.1 Synthesis and Bromination of 4-(Cinnamoyloxyimino)-
cyclohexa-2,5-dienones
S. A. Konovalovaa, A. P. Avdeenkoa,* and S. A. Goncharovab
a Donbass State Engineering Academy, ul. Shkadinova 72, Kramatorsk, 84313 Ukraine
*e-mail: chimist@dgma.donetsk.ua
b Sumy State University, ul. Rimskogo-Korsakova 2, Sumy, 40007 Ukraine
Received April 12, 2016
Abstract—New 4-(cinnamoyloxyimino)cyclohexa-2,5-dien-1-ones were synthesized, and their bromination
afforded bromine addition products to the syn- and anti-C=C bonds of the quinoid ring. In all cases, bromine
addition to the C=C double bond of the cinnamoyl fragment was observed.
DOI: 10.1134/S1070428016070034
We previously synthesized new N-benzylidene-
acetyl-substituted 1,4-benzoquinone imines by reac-
tions of the corresponding 4-aminophenols with ben-
zylideneacetyl chloride (3-phenylacryloyl chloride) [2].
Carboxylic acid chlorides are capable of reacting not
only with aminophenols but also with p-quinone mono-
oximes to give p-quinone monooxime O-ethers [3]; the
latter were found to undergo regioselective halogena-
tion of the double bonds in the quinoid ring [4].
The goal of the present work was to synthesize new
4-(cinnamoyloxyimino)cyclohexa-2,5-dien-1-ones and
study their halogenation. By reaction of 4-(hydroxy-
imino)cyclohexa-2,5-dien-1-ones 1a–1h with 3-phe-
nylacryloyl chloride (2) in diethyl ether in the presence
of triethylamine on cooling we obtained 4-(cin-
namoyloxyimino)cyclohexa-2,5-dien-1-ones 3a–3h
(Scheme 1) whose structure was confirmed by elemen-
tal analyses and 1H NMR and IR spectra. The IR spec-
tra of 3a–3h contained absorption bands at 1620–1660
(C=O, quinone), 1680–1730 (C=O, ester), and 1550–
1620 cm–1 (C=N). In the 1H NMR spectra of 3a–3h we
observed two doublets in the δ range from 6.88 to
7.53 ppm due to protons of the exocyclic CH=CH
fragment, and the positions and multiplicities of
signals from protons of the quinoid ring were fully
1
consistent with the proposed structures. The H NMR
spectrum of 2-methyl derivative 3b displayed a double
set of signals due to the presence of Z and E isomers
with respect to the C=N bond at a ratio of 60:40; the
Gibbs free energy of activation for the Z/E isomeriza-
tion of 4-(hydroxyimino)cyclohexa-2,5-dien-1-ones
about the C=N bond was estimated at ΔG≠ > 100 kJ×
Scheme 1.
R1
R1
R2
N
O
R2
N
O
Ph
Cl
+
HO
Ph
O
R4
R4
O
R3
1a–1h
O
R3
2
3a–3h
R1 = R2 = R3 = R4 = H (a); R1 = Me, R2 = R3 = R4 = H (b); R1 = R3 = R4 = H, R2 = Me (c); R1 = R2 = Me, R3 = R4 = H (d); R1 = R3 =
Me, R2 = R4 = H (e); R1 = R4 = Me, R2 = R3 = H (f); R1 = R4 = H, R2 = R3 = Me (g); R1 = Me, R2 = R4 = H, R3 = i-Pr (h).
1
For communication XIV, see [1].
939

KONOVALOVA et al.
940
Me
O
O
Ph
O
Ph
O
N
N
Me
O
O
Z-3b
E-3b
mol–1 [5]. The 3-H proton in 3b resonated as a quartet
at δ 7.44 (Z) or 7.26 ppm (E), the 5-H signal was
a doublet of doublets at δ 7.37–7.40 (Z) or 7.73–
7.77 ppm (E), and the 6-H proton gave a doublet
(vicinal coupling) at δ 6.68 (Z) or 6.59 ppm (E).
and 2-H signals were doublets of doublets at δ 4.73
and 6.19 (E) and 4.58 and 6.34 ppm (Z), respectively.
According to the data of [5], no Z,E-isomerization
of p-quinone monooxime O-ethers is observed at room
temperature, and the Z and E isomers are converted
into each other neither in initial solution nor during
halogenation [4]. Therefore, the isomer ratio of the
halogenation products should be the same as that of
initial O-substituted p-quinone monooximes.
The chlorination of 3a–3h was carried out by
saturation with gaseous chlorine. As a result, complex
non-crystallizable mixtures of products were formed,
which we failed to isolate and identify. The bromina-
tion of 3a–3h was performed in acetic acid using
5 equiv of bromine. Crystalline bromination products
As shown previously, the ratio of the halogen
addition products to the syn- and anti-C=C bonds of
the quinoid ring is determined by two factors, elec-
tronic (acceptor properties of the substituent on the
nitrogen atom) and steric (size of substituents in the
quinoid ring) [4, 6, 7]. The syn-C2=C3 bond in
O-arenesulfonyl-substituted p-quinone monooximes is
more reactive due to its lower polarity (the conjugation
along the N=C–C2=C3–C=O bond sequence is weaker
than that along the N=C–C5=C6–C=O sequence) [4],
while reduction of the acceptor power of the ArNHCO
substituent on the oxygen atom in O-arylamino-
carbonyl derivatives leads to leveling of the reactivities
of the quinoid C=C bonds toward halogens [8].
1
were analyzed by H NMR before recrystallization in
order to detect all components of the product mixtures.
The regioselectivity of halogen addition to the
double bonds of the quinoid ring was studied for un-
substituted and 2,6(3,5)-dimethyl-substituted deriva-
tives with a symmetric structure of the quinoid ring
[4]. The bromination of 3a, 3f, and 3g gave mixtures
of Z- and E-isomeric products at ratios of 36:64 (4a),
42 :58 (4f), and 36:64 (4g) as a result of bromine
addition to the syn- or anti-C=C bond with respect to
the substituent on the nitrogen (Scheme 2).
1
In the H NMR spectrum of 4a, the 5-H and 6-H
signals were quartets at δ 4.68 and 5.73 ppm (E) and
4.81 and 5.40 ppm (Z), respectively; the 2-H and 3-H
protons resonated as doublets of doublets at δ 6.49–
6.53 (2-H, E), 6.43–6.47 (2-H, Z), 7.23–7.26 (3-H, E),
and 7.57–7.61 ppm (3-H, Z). The doublet signal from
the 2-Me protons of 4f was located at δ 2.17 (Z) and
2.14 (E), and from the 6-Me group, at δ 2.14 (Z) and
2.12 ppm (E). The 5-Me signal of both isomers of 4g
was a singlet at δ 2.34 ppm, the 3-Me group gave rise
to doublets at δ 2.61 (E) and 2.59 ppm (Z), and the 6-H
The results of bromination of compounds 3a, 3f,
and 3g showed that the fraction of the E isomer
(Scheme 2) arising from the addition of bromine to the
syn-C=C bond is considerably smaller than in the
halogenation of 4-(arenesulfonyloxyimino)cyclohexa-
2,5-dien-1-ones (80–85% of the E isomer) [9] and is
comparable with that in the halogenation of 4-(car-
bamoyloxyimino)cyclohexa-2,5-dien-1-ones (58–64%
of the E isomer) [8]. Therefore, we can conclude that
the PhCH=CHCO substituent on the oxime oxygen
Scheme 2.
R1
R4
Br
Br
R3
R2
N
O
O
Br2
Br
Br
3a–3h
+
Ph
O
R4
Br
Ph
O
N
R1
R3
Br
O
Br
O
R2
Br
Z-4a, Z-4b, Z-4f, Z-4g
E-4a–E-4h
R1 = R2 = R3 = R4 = H (a); R1 = Me, R2 = R3 = R4 = H (b); R1 = R3 = R4 = H, R2 = Me (c); R1 = R2 = Me, R3 = R4 = H (d); R1 = R3 =
Me, R2 = R4 = H (e); R1 = R4 = Me, R2 = R3 = H (f); R1 = R4 = H, R2 = R3 = Me (g); R1 = Me, R2 = R4 = H, R3 = i-Pr (h).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 7 2016

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... XV.
941
atom of 3a, 3f, and 3g, as well as ArNHCO group,
exerts a weaker acceptor effect on the quinoid double
bonds than does arenesulfonyl group.
While studying the mechanism of halogenation of
p-quinone monooxime O-esters [4], the bromination of
4-aroyl(arenesulfonyl)oxyimino-2,3-dimethylcyclo-
hexa-2,5-dien-1-ones was carried out in the presence
of LiCl. In this work we also performed bromination of
3d in acetic acid in the presence of LiCl, which led to
the formation of a mixture of compounds 4d and 5 at
a ratio of 47:53 (Scheme 3).
The bromination of 3b gave a mixture of Z-4b and
E-4b at a ratio of 58:42 (Scheme 2). Bromine mole-
cule adds exclusively to the unsubstituted C=C bond,
and the isomer ratio Z-4b/E-4b is the same as
Z-3b/E-3b; i.e., E-3b is converted to E-4b, and Z-3b to
Z-4b. This is one more proof for the fact that the Z and
E isomers of p-quinone monooxime O-ethers are not
converted into each other during the halogenation
process. The absence of addition products to the C2=C3
bond of 3b containing a methyl group also indicates
reduced acceptor effect of the PhCH=CHC(O) or
PhC(Br)H–C(Br)HC(O) substituent on the oxygen
atom as compared to arenesulfonyl group. The direc-
tion of halogen addition is determined mainly by steric
factor, and the reaction becomes completely regio-
selective since the presence of a methyl group on C2
hampers addition to the C2=C3 bond.
Scheme 3.
Cl
Br
O
Br2, LiCl
Br
3d
E-4d +
Ph
O
N
Me
Br
O
Me
5
Comparison of the spectral data showed that the
bromine and chlorine atoms in 5 are attached to C5 and
C6, respectively. The 6-H and 5-H protons resonated as
doublets at δ 4.69 and 5.77 (4d) and 4.57 and 5.76 ppm
(5), respectively. The 6-H signal of 5 appeared in
a stronger field relative to the corresponding signal of
4d, indicating that the chlorine atom is located in the
ortho position with respect to the carbonyl group. This
is consistent with the results of halogenation of
4-aroyl- and 4-arenesulfonyloxyimino analogs [4].
The structure of the Z and E isomers of 4b was
1
determined by comparing their H NMR data with
those of the halogenation products of 4-(aroyloxy-
imino)-2-methylcyclohexa-2,5-dien-1-ones [4, 10]. In
1
the H NMR spectrum of 4b, the 3-H and 5-H protons
resonated as quartets at δ 7.41 and 5.38 (Z) and 7.05
and 5.69 ppm (E), respectively, and the 2-Me and 6-H
signals appeared as doublets (meta coupling) at δ 2.16
and 4.82 (Z) and 2.13 and 4.69 ppm (E).
In keeping with the classical theory, the addition of
bromine to double C=C bond involves initial formation
of a π-complex which is then converted to bromonium
ion [12]. Depending on the conditions, the latter either
reacts directly with bromide ion or is transformed to
carbenium ion which in turn takes up bromide ion.
As shown in [4], the formation of carbenium ion is
possible only in the halogenation of 1,4-benzoquinone
imines but is not typical of 1,4-quinone monooxime
ethers [4].
The bromination of 3c, 3d, 3e, and 3h, which were
obtained as a single isomer, afforded only the syn-
addition products, E isomers 4c, 4d, 4e, and 4h
(Scheme 2), whose structure was confirmed by
1H NMR and elemental analyses. Analogous aroyl and
arenesulfonyl derivatives reacted with bromine to give
addition products to both syn- and anti-C=C bonds of
the quinoid ring [4, 11].
In all cases, bromination of the quinoid ring of
3a–3h was accompanied by bromine addition to the
exocyclic double bond of the cinnamoyl fragment, and
the reaction mixtures contained no dehydrobromina-
tion products like those obtained previously in the
halogenation of aroyl, arenesulfonyl [4, 9–11], and
carbamoyl derivatives [8].
In order to get a deeper insight into the mechanism
of bromination of compounds 3a–3h, we performed
quantum chemical calculations of possible interme-
diates A–C in the bromination of 3d. All attempts to
optimize the structures of carbocations B and C were
unsuccessful; the optimization process resulted in
H
H
Br
Br
O
O
H
H
Ph
O
Ph
O
N
Me
N
Me
O
Me
O
Me
A
B
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 7 2016

KONOVALOVA et al.
942
H
Br
H
O
Br
H
N
O
H
Cl–
Ph
O
Ph
O
Me
N
Me
O
Me
O
Me
Me
C
D
Me
Br
H
O
H
O
H
H
Ph
O
Ph
O
N
N
Br
O
Me
O
Me
E
F
rupture of the C–O bond in the C=NOC=O fragment;
therefore, we presumed that no carbocation is formed
in the bromination of 3d.
gen atom in 4-(cinnamoyloxyimino)cyclohexa-2,5-di-
en-1-ones affects the regioselectivity of halogen addi-
tion to the quinoid C=C bonds to a smaller extent than
in 4-(arenesulfonyloxyimino)cyclohexa-2,5-dien-
1-ones, which is related to weaker acceptor effect of
the PhCH=CHC(O) substituent on the quinoid ring.
It may be concluded that the first step in the
bromination of 3d is addition of bromine cation to the
quinoid C=C bond with formation of bromonium ion
A. Next follows trans-addition of bromide ion (or
chloride in the reaction in the presence of LiCl), which
is confirmed by quantum chemical calculations (opti-
mization of intermediate D led to a structure analogous
to 5) and is very consistent with the results of halo-
genation of 4-(aroyloxyimino)- and 4-(arenesulfonyl-
oxyimino)cyclohexa-2,5-dien-1-ones [4].
EXPERIMENTAL
1
The H NMR spectra were recorded on a Varian
VXR-300 spectrometer at 300 MHz using CDCl3 as
solvent and tetramethylsilane as internal standard. The
purity of compounds 3a–3h, 4a–4h, and 5 was
checked by TLC on Silufol UV-254 plates; samples
were applied from solutions in chloroform, ethanol–
chloroform (1:10) was used as eluent, and spots were
visualized under UV light.
The total energy of optimized structure 5 is lower
by 15 kJ/mol than the energy of the alternative isomer
with the chlorine atom attached to C5 (i.e., in the ortho
position with respect to the imino group) and the
bromine atom on C6. An additional evidence in support
of the proposed mechanism is that the halogenation of
O-substituted p-quinone monooximes gave only prod-
ucts with trans arrangement of the halogen atoms on
the sp3-carbon atoms of the cyclohexene ring.
Quantum chemical calculations were performed in
terms of the density functional theory with the B3LYP
functional and 6-31+G(d) basis set using Firefly QC
package [13] based in part on the GAMESS (US)
code [14].
3-Phenylacryloyl chloride (2) was synthesized
according to the procedure described in [15] and was
recrystallized from hexane.
In order to rationalize different reactivities of the
C=C bonds in the quinoid ring, we performed quantum
chemical calculations of possible intermediates, bro-
monium ions E and F, corresponding to the bromina-
tion of 3c, 3e, and 3h. The energy of transition state F
was estimated at –3508.658078 Ha, while attempted
optimization of structure E led to rupture of the O–C
bond in the C=NO–C=O fragment, which indicated
its instability. Thus, the bromination of 2,5-dialkyl-
substituted 4-(cinnamoyloxyimino)cyclohexa-2,5-dien-
1-ones does not give addition products to the anti-C=C
bond since the formation of the corresponding bromo-
nium ion is impossible.
4-{[(Cinnamoyl)oxy]imino}cyclohexa-2,5-dien-1-
ones 3a–3h (general procedure). Quinone oxime 1a–
1h, 0.01 mol, was dispersed in 30–35 mL of anhydrous
diethyl ether, and an equimolar amount of 3-phenyl-
acryloyl chloride (2) and 0.011 mol of triethylamine
were slowly added with stirring and cooling. A crys-
talline solid separated from the mixture and was
filtered off, washed with water, and recrystallized from
glacial acetic acid or isopropyl alcohol.
4-{[(3-Phenylprop-2-enoyl)oxy]imino}cyclohexa-
2,5-dien-1-one (3a). Yield 48%, mp 102–103°C.
1H NMR spectrum, δ, ppm: 6.60 d.d (1H, 6-H, J = 1.8,
The results of our present study showed that the
orientation (syn or anti) of the substituent on the nitro-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 7 2016

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... XV.
943
10.5 Hz), 6.63 d (1H, CH=CH, J = 15.9 Hz), 6.64 d.d
(1H, 2-H, J = 1.8, 10.5 Hz), 7.46 d.d (1H, 5-H, J = 2.4,
10.5 Hz), 7.45–7.63 m (5H, Ph), 7.81 d.d (1H, 3-H,
J = 2.4, 10.5 Hz), 7.96 d (1H, CH=CH, J = 15.9 Hz).
Found, %: N 5.63, 5.41. C15H11NO3. Calculated, %:
N 5.53.
CH=CH, J = 15.9 Hz). Found, %: N 5.00, 4.85.
C17H15NO3. Calculated, %: N 4.98.
3,5-Dimethyl-4-{[(3-phenylprop-2-enoyl)oxy]-
imino}cyclohexa-2,5-dien-1-one (3g). Yield 54%,
1
mp 175–176°C. H NMR spectrum, δ, ppm: 2.36 d
(3H, 3-Me, J = 1.5 Hz), 2.56 d (3H, 5-Me, J = 1.5 Hz),
6.29 q (1H, 6-H), 6.40 q (1H, 2-H), 6.58 d (1H,
CH=CH, J = 16.2 Hz), 7.44–7.63 m (5H, Ph), 7.93 d
(1H, CH=CH, J = 15.9 Hz). Found, %: N 5.05, 4.79.
C17H15NO3. Calculated, %: N 4.98.
2-Methyl-4-{[(3-phenylprop-2-enoyl)oxy]imino}-
cyclohexa-2,5-dien-1-one (3b). Yield 56%, mp 145–
1
146°C. H NMR spectrum, δ, ppm: Z isomer (60%):
2.13 d (3H, 2-Me, J = 1.5 Hz), 6.63 d (1H, CH=CH,
J = 15.9 Hz), 6.68 d (1H, 6-H, J5,6 = 9.9 Hz), 7.39 d.d
(1H, 5-H, J = 2.7, 9.9 Hz), 7.44 q (1H, 3-H), 7.44–
7.63 m (5H, Ph), 7.97 d (1H, CH=CH, J = 15.9 Hz);
E isomer (40%): 2.08 d (3H, 2-Me, J = 1.5 Hz), 6.59 d
(1H, 6-H, J5,6 = 9.9 Hz), 6.63 d (1H, CH=CH, J =
15.9 Hz), 7.26 q (1H, 3-H), 7.44–7.63 m (5H, Ph),
7.75 d.d (1H, 5-H, J = 2.7, 9.9 Hz), 7.95 d (1H,
CH=CH, J = 15.9 Hz). Found, %: N 5.30, 5.14.
C16H13NO3. Calculated, %: N 5.24.
5-Isopropyl-2-methyl-4-{[(3-phenylprop-2-
enoyl)oxy]imino}cyclohexa-2,5-dien-1-one (3h).
1
Yield 73%, mp 104–105°C. H NMR spectrum, δ,
ppm: 1.25 d [6H, CH(CH3)2, J = 6.9 Hz], 2.09 br.s
(3H, 2-Me), 3.44–3.53 m [1H, CH(CH3)2], 6.43 br.s
(1H, 6-H), 6.68 d (1H, CH=CH, J = 15.6 Hz), 7.44–
7.63 m (5H, Ph), 7.60 br.s (1H, 3-H), 7.93 d (1H,
CH=CH, J = 16.5 Hz). Found, %: N 4.61, 4.38.
C19H19NO3. Calculated, %: N 4.53.
3-Methyl-4-{[(3-phenylprop-2-enoyl)oxy]imino}-
cyclohexa-2,5-dien-1-one (3c). Yield 64%, mp 177–
178°C. 1H NMR spectrum, δ, ppm: 2.37 s (3H, 3-Me),
6.44 q (1H, 2-H), 6.53 d.d (1H, 6-H, J = 1.8, 10.2 Hz),
6.65 d (1H, CH=CH, J = 16.2 Hz), 6.78 d (1H, 5-H,
J = 10.2 Hz), 7.44–7.63 m (5H, Ph), 7.93 d (1H,
CH=CH, J = 16.2 Hz). Found, %: N 5.34, 5.10.
C16H13NO3. Calculated, %: N 5.24.
Bromination of 4-{[(cinnamoyl)oxy]imino}cy-
clohexa-2,5-dien-1-ones 3a–3h (general procedure).
A solution of 5 mmol of compound 3a–3h in 3 mL of
acetic acid was heated to the boiling point, a solution
of 25 mmol of bromine in 2 mL of acetic acid heated
to 50–60°C was added dropwise under vigorous
stirring, and the mixture was refluxed for 5–10 min
under vigorous stirring. The mixture was cooled, and
the precipitate was filtered off and recrystallized from
acetic acid.
2,3-Dimethyl-4-{[(3-phenylprop-2-enoyl)oxy]-
imino}cyclohexa-2,5-dien-1-one (3d). Yield 70%,
1
mp 185–186°C. H NMR spectrum, δ, ppm: 2.06 s
5,6-Dibromo-4-{[(2,3-dibromo-3-phenylpro-
(3H, 2-Me), 2.35 s (3H, 3-Me), 6.53 d (1H, 6-H, J =
10.2 Hz), 6.65 d (1H, CH=CH, J = 15.9 Hz), 7.44–
7.62 m (5H, Ph), 7.75 d (1H, 5-H, J = 10.2 Hz), 7.94 d
(1H, CH=CH, J = 15.9 Hz). Found, %: N 5.00, 5.15.
C17H15NO3. Calculated, %: N 4.98.
panoyl)oxy]imino}cyclohex-2-en-1-one (4a). Yield
1
54%, mp 129–130°C. H NMR spectrum, δ, ppm:
Z isomer (36%): 4.81 q (1H, 6-H), 5.07 d (1H,
CHBrCHBr, J = 11.7 Hz), 5.40 q (1H, 5-H), 5.42 d
(1H, CHBrCHBr, J = 11.7 Hz), 6.45 d (1H, 2-H, J =
9.3 Hz), 7.42–7.52 m (5H, Ph), 7.59 d (1H, 3-H, J =
9.6 Hz); E isomer (64%): 4.68 q (1H, 6-H), 5.07 d and
5.47 d (1H each, CHBrCHBr, J = 11.7 Hz), 5.73 q
(1H, 5-H), 6.50 d (1H, 2-H, J = 9.3 Hz), 7.24 d (1H,
3-H, J = 9.6 Hz), 7.42–7.52 m (5H, Ph). Found, %:
Br 55.60, 55.52; N 2.35, 2.55. C15H11Br4NO3. Cal-
culated, %: Br 55.79; N 2.45.
2,5-Dimethyl-4-{[(3-phenylprop-2-enoyl)oxy]-
imino}cyclohexa-2,5-dien-1-one (3e). Yield 82%,
1
mp 195–196°C. H NMR spectrum, δ, ppm: 2.08 d
(3H, 2-Me, J = 1.5 Hz), 2.33 d (3H, 5-Me, J = 1.5 Hz),
6.41 q (1H, 6-H), 6.70 d (1H, CH=CH, J = 15.6 Hz),
7.43–7.63 m (5H, Ph), 7.57 q (1H, 3-H), 7.93 d (1H,
CH=CH, J = 16.2 Hz). Found, %: N 5.05, 5.10.
C17H15NO3. Calculated, %: N 4.98.
5,6-Dibromo-4-{[(2,3-dibromo-3-phenylpro-
panoyl)oxy]imino}-2-methylcyclohex-2-en-1-one
2,6-Dimethyl-4-{[(3-phenylprop-2-enoyl)oxy]-
1
imino}cyclohexa-2,5-dien-1-one (3f). Yield 76%,
(4b). Yield 62%, mp 163–164°C. H NMR spectrum,
1
mp 139–140°C. H NMR spectrum, δ, ppm: 2.07 d
δ, ppm: Z isomer (58%): 2.16 d (3H, 2-Me, J =
1.5 Hz), 4.82 d (1H, 6-H, J = 2.7 Hz), 5.06 d (1H,
CHBrCHBr, J = 11.7 Hz), 5.38 q (1H, 5-H), 7.39–
7.50 m (5H, Ph), 7.41 q (1H, 3-H), 5.43 d (1H,
(1H, 2-Me, J = 1.2 Hz), 2.13 d (1H, 6-Me, J = 1.2 Hz),
6.65 d (1H, CH=CH, J = 16.2 Hz), 7.18 q (1H, 5-H),
7.57 q (1H, 3-H), 7.43–7.63 m (5H, Ph), 7.94 d (1H,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 7 2016

KONOVALOVA et al.
944
CHBrCHBr, J = 11.7 Hz); E isomer (42%): 2.13 d (3H,
2-Me, J = 0.9 Hz), 4.69 d (1H, 6-H, J = 3.0 Hz), 5.06 d
(1H, CHBrCHBr, J = 11.7 Hz), 7.39–7.50 m (5H, Ph),
5.43 d (1H, CHBrCHBr, J = 11.7 Hz), 5.69 q (1H, 5-H),
7.05 q (1H, 3-H). Found, %: Br 54.30, 54.55; N 2.47,
2.25. C16H13Br4NO3. Calculated, %: Br 54.46; N 2.39.
7.44–7.63 m (5H, Ph); E isomer (64%): 2.34 s (3H,
5-Me), 2.61 d (3H, 3-Me, J = 2.1 Hz), 4.73 q (1H,
6-H), 5.01 d and 5.41 d (1H each, CHBrCHBr, J =
11.7 Hz), 6.19 q (1H, 2-H), 7.44–7.63 m (5H, Ph).
Found, %: Br 53. 02, 53. 27; N 2. 41, 2. 50.
C17H15Br4NO3. Calculated, %: Br 53.19; N 2.33.
5,6-Dibromo-4-{[(2,3-dibromo-3-phenylpro-
panoyl)oxy]imino}-3-isopropyl-6-methylcyclohex-2-
en-1-one (4h). Yield 76%, mp 117–118°C. H NMR
spectrum, δ, ppm: 1.26 d [6H, CH(CH3)2, J = 6.9,
13.6 Hz], 2.09 s (3H, 6-Me), 3.30–3.41 m [1H,
CH(CH3)2], 5.11 d and 5.42 d (1H each, CHBrCHBr,
J = 12.0 Hz), 5.89 d (1H, 2-H, J = 2.7 Hz), 6.32 br.s
(1H, 5-H), 7.41–7.50 m (5H, Ph). Found, %: Br 50.68,
50.75; N 2.15, 2.31. C19H19Br4NO3. Calculated, %:
Br 50.82; N 2.23.
5,6-Dibromo-4-{[(2,3-dibromo-3-phenylpro-
panoyl)oxy]imino}-3-methylcyclohex-2-en-1-one
(4c). Yield 78%, mp 164–165°C. 1H NMR spectrum, δ,
ppm: 2.37 d (3H, 3-Me, J = 1.5 Hz), 4.64 q (1H, 6-H),
5.04 d and 5.43 d (1H each, CHBrCHBr, J = 9.9 Hz),
7.42–7.50 m (5H, Ph), 5.77 d (1H, 5-H, J = 2.4 Hz),
6.34 q (1H, 2-H). Found, %: Br 54.27, 54.64; N 2.45,
2.60. C16H13Br4NO3. Calculated, %: Br 54.46; N 2.39.
1
5,6-Dibromo-4-{[(2,3-dibromo-3-phenylpro-
panoyl)oxy]imino}-2,3-dimethylcyclohex-2-en-1-one
1
Bromination of 2,3-dimethyl-4-{[(3-phenylprop-
2-enoyl)oxy]imino}cyclohexa-2,5-dien-1-one (3d) in
the presence of LiCl. A solution of 5 mmol of
compound 3d in 3 mL of acetic acid was heated to the
boiling point, an equimolar amount of lithium chloride
was added in portions under stirring, and a solution of
25 mmol of bromine in 2 mL of acetic acid heated to
50–60°C was then added dropwise under vigorous
stirring. The mixture was refluxed for 5–10 min with
stirring. After cooling, the precipitate was filtered off
and recrystallized from acetic acid.
(4d). Yield 70%, mp 186–187°C. H NMR spectrum,
δ, ppm: 2.11 s (3H, 2-Me), 2.34 s (3H, 3-Me), 4.69 d
(1H, 6-H, J = 2.1 Hz), 5.07 d and 5.43 d (1H each,
CHBrCHBr, J = 11.7 Hz), 7.41–7.46 m (5H, Ph),
5.77 d (1H, 5-H, J = 2.1 Hz). Found, %: Br 53.10,
53.28; N 2.53, 2.25. C17H15Br4NO3. Calculated, %:
Br 53.19; N 2.33.
5,6-Dibromo-4-{[(2,3-dibromo-3-phenylpro-
panoyl)oxy]imino}-3,6-dimethylcyclohex-2-en-1-one
1
(4e). Yield 50%, mp 91–92°C. H NMR spectrum, δ,
ppm: 2.10 s (3H, 6-Me), 2.34 d (3H, 3-Me, J =
1.2 Hz), 5.11 d and 5.43 d (1H each, CHBrCHBr, J =
11.7 Hz), 5.86 d (1H, 5-H, J = 2.7 Hz), 6.34 q (1H,
2-H), 7.42–7.49 m (5H, Ph). Found, %: Br 53.08,
53.31; N 2.40, 2.20. C17H15Br4NO3. Calculated, %:
Br 53.19; N 2.33.
5-Bromo-6-chloro-4-{[(2,3-dibromo-3-phenyl-
propanoyl)oxy]imino}-2,3-dimethylcyclohex-2-en-1-
one (5). 1H NMR spectrum, δ, ppm: 2.11 s (3H, 2-Me),
2.34 s (3H, 3-Me), 4.57 d (1H, 6-H, J = 2.1 Hz), 5.07 d
and 5.42 d (1H each, CHBrCHBr, J = 11.7 Hz), 5.76 d
(1H, 5-H, J = 2.4 Hz), 7.42–7.46 m (5H, Ph).
5,6-Dibromo-4-{[(2,3-dibromo-3-phenylpro-
panoyl)oxy]imino}-2,6-dimethylcyclohex-2-en-1-one
(4f). Yield 69%, mp 139–140°C. 1H NMR spectrum, δ,
ppm: Z isomer (42%): 2.14 s (3H, 6-Me), 2.17 d (3H,
2-Me, J = 1.2 Hz), 5.05 d and 5.45 d (1H each,
CHBrCHBr, J = 11.7 Hz), 5.45 q (1H, 5-H), 7.32 q
(1H, 3-H) 7.42–7.46 m (5H, Ph); E isomer (58%):
2.12 s (6H, 6-Me), 2.14 d (3H, 2-Me, J = 1.2 Hz),
5.08 d and 5.44 d (1H each, CHBrCHBr, J = 11.7 Hz),
7.42–7.46 m (5H, Ph), 5.79 q (1H, 5-H), 6.98 q (1H,
3-H). Found, %: Br 53.12, 53.25; N 2.51, 2.42.
C17H15Br4NO3. Calculated, %: Br 53.19; N 2.33.
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