Halogenation of N-substituted p-quinone monoimines and p-quinone monooxime esters: VII. Halogenation of 4-aroyl(arylsulfonyl)imino- and 4-aroyl(arylsulfonyl)-oxyimino-2,6-diisopropylcyclohexa-2,5-dien-1-ones

Article abstract of DOI:10.1134/S1070428008040131

Halogenation of 4-aroyl(arylsulfonyl)imino-2,6-diisopropylcyclohexa-2,5- dien-1-ones gave 4-aroyl-(arylsulfonyl)imino-3-halo-2,6-diisopropylcyclohexa-2, 5-dien-1-ones and 4-aroyl(arylsulfonyl)imino-3,5,6-trihalo-2,6- diisopropylcyclohex-2-en-1-ones. The l

Full text of DOI:10.1134/S1070428008040131

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2008, Vol. 44, No. 4, pp. 542–552. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © A.P. Avdeenko, V.V. Pirozhenko, O.V. Shishkin, S.V. Shishkina, S.A. Konovalova, O.N. Ludchenko, 2008, published in Zhurnal
Organicheskoi Khimii, 2008, Vol. 44, No. 4, pp. 547–557.
Halogenation of N-Substituted p-Quinone Monoimines
and p-Quinone Monooxime Esters: VII.* Halogenation
of 4-Aroyl(arylsulfonyl)imino- and 4-Aroyl(arylsulfonyl)-
oxyimino-2,6-diisopropylcyclohexa-2,5-dien-1-ones
A. P. Avdeenkoa, V. V. Pirozhenkob, O. V. Shishkinc, S. V. Shishkinac, S. A. Konovalovaa,
and O. N. Ludchenkoa
a Donbass State Machine-Building Academy, ul. Shkadinova 72, Kramatorsk, 84313 Ukraine
e-mail: chimist@dgma.donetsk.ua
b Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev, Ukraine
c Institute of Single Crystals, National Academy of Sciences of Ukraine, Khar’kov, Ukraine
Received March 10, 2007
Abstract—Halogenation of 4-aroyl(arylsulfonyl)imino-2,6-diisopropylcyclohexa-2,5-dien-1-ones gave 4-aroyl-
(arylsulfonyl)imino-3-halo-2,6-diisopropylcyclohexa-2,5-dien-1-ones and 4-aroyl(arylsulfonyl)imino-3,5,6-tri-
halo-2,6-diisopropylcyclohex-2-en-1-ones. The latter were formed as mixtures of two stereoisomers, and the
isopropyl group on the sp3-hybridized carbon atom in one stereoisomer occupies axial position, which is
untypical of such compounds. Halogenation of 4-aroyl(arylsulfonyl)oxyimino-2,6-diisopropylcyclohexa-2,5-di-
en-1-ones leads to the formation of the corresponding addition products with traditional trans-diaxial arrange-
ment of the halogen atoms.
DOI: 10.1134/S1070428008040131
The present work continues our studies in the field
of halogenation of N-substituted 1,4-benzoquinone
monoimines [1] and 1,4-benzoquinone monooxime
ethers [2]. On the basis of our experimental data and
the results of semiempirical calculations we previously
presumed that halogenation of 1,4-benzoquinone
imines and 1,4-benzoquinone oxime ethers initially
involves formation of intermediate halonium ion or
carbocation [1–3]. According to semiempirical calcula-
tions, in the bromination of 1,4-benzoquinone oxime
ethers, bromonium ion is more thermodynamically
stable [2], so that the process is strictly stereoselective
(only trans-addition is possible), and the products are
characterized by trans-diaxial arrangement of the
bromine atoms. In the halogenation of N-arylsulfonyl-
1,4-benzoquinone imines, the corresponding carbo-
cation is thermodynamically more stable [1], and the
process is completely regioselective but not strictly
stereoselective: the addition occurs at only one C=C
bond in the quinoid ring, but both trans- and cis-addi-
tion is possible. The stereoisomer ratio depends on the
steric structure of intermediate carbocation.
The results of our previous studies on the UV and
1H NMR spectra (specifically, 2-H–3-H and 5-H–6-H
coupling constants) of 5,6-dichlorocyclohex-2-ene-1,4-
diones formed by addition of a halogen molecule to
1,4-benzoquinones led us to assign trans-diaxial
orientation of chlorine atoms in their molecules [4, 5].
Our subsequent studies on halogenation of quinoid
systems showed that addition of halogens across the
quinoid C=C bonds gives products in which the halo-
gen atoms at the sp3-hybridized carbon atoms always
occupy axial positions and are arranged trans while
hydrogen atoms or alkyl groups occupy equatorial
positions [2]. In most cases, the substrates were
methyl-substituted benzoquinone derivatives. No halo-
genation products with axial orientation of alkyl sub-
stituents were detected.
Taking into account the data of [1, 2], we antici-
pated that the presence of bulky electron-donating
groups in the quinoid ring and polar solvents should
* For communication VI, see [1].
542

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... VII.
543
Scheme 1.
O
O
OH
Pr-i
Cl
i-Pr
Pr-i
i-Pr
i-Pr
Pr-i
Cl2
Cl2
Cl
Cl
XAr
N
N
HN
XAr
XAr
Ia, Ic, Id, IIa, IIb
XIIa, XIIc, XIId, XIIIa, XIIIb
IIIa–IIId, IVa, IVb
OH
O
i-Pr
Pr-i
i-Pr
Pr-i
Hlg2
[O]
IIIa–IIId, IVa, IVb
Hlg
Hlg
HN
N
XAr
XAr
Va, Vb, VIa, VIb, VIIa, VIIb
VIIIa, VIIId, IXa, IXb
Xa, Xb, XIa, XIb
Ar = Ph (a), 4-MeC6H4 (b), 4-MeOC6H4 (c), 4-O2NC6H4 (d); I, III, V, VIII, IX, XII, X = CO; II, IV, VI, VII, X, XI, XIII,
X = SO2; VI, VIII, X, Hlg = Cl; V, VII, IX, XI, Hlg = Br.
stabilize the corresponding carbocation and hence
favor formation of halogen addition products having
axially oriented alkyl groups [3, 6]. Thus the goal of
the present work was to elucidate how bulky electron-
donating isopropyl groups in positions 2 and 6 of the
quinoid ring and solvent polarity affect halogenation
of N-substituted 1,4-benzoquinone imines and 1,4-ben-
zoquinone oxime ethers. For this purpose we examined
halogenation of 4-aroyl(arylsulfonyl)imino-2,6-diiso-
propylcyclohexa-2,5-dien-1-ones I and II and their
reduction products, the corresponding 4-aroyl(arylsul-
fonyl)amino-2,6-diisopropylphenols III and IV
(Scheme 1).
imino-5,6-dichloro-2,6-dimethylcyclohex-2-en-1-ones
were found to exist as two isomers. As we noted in [7],
semiquinoid compounds capable of undergoing Z,E
isomerization with respect to the C=N bond become
highly reactive, for cis-arrangement of the substituent
on the nitrogen atom relative to the C=C bond favors
their dehydrohalogenation [7].
The bromination of quinone imines Ia, Ic, Id, IIa,
and IIb led to the formation of noncrystallizable oily
mixtures of products whose composition was not
determined.
Depending on the solvent nature and reactant ratio,
halogenation of 4-aroyl(arylsulfonyl)amino-2,6-diiso-
propylphenols IIIa–IIId, IVa, and IVb afforded
4-aroylamino-3-bromo-2,6-diisopropylphenols Va and
Vb, 4-arylsulfonylamino-3-halo-2,6-diisopropyl-
phenols VIa, VIb, VIIa, and VIIb, and semiquinoid
compounds XIIa, XIIc, XIId, XIIIa, and XIIIb.
N-Aroyl(arylsulfonyl)-3-bromo-2,6-diisopropyl-1,4-
benzoquinone imines IXa, IXb, XIa, and XIb and
N-arylsulfonyl-3-chloro-2,6-diisopropyl-1,4-benzo-
quinone imines Xa and Xb were obtained by oxidation
of the corresponding aminophenols Va, Vb, VIa, VIb,
VIIa, and VIIb with lead tetraacetate. We failed to
isolate individual N-aroyl-3-chloro-2,6-diisopropyl-
1,4-benzoquinone imines VIIIa and VIIId in the
chlorination of quinone imines Ia and Id and amino-
phenols IIIa and IIId. Compounds VIIIa and VIIId
were isolated as mixtures with semiquinoid derivatives
XIIIa and XIIId in the chlorination of quinone imines
Ia and Id.
Compounds I and II were treated with gaseous
chlorine or molecular bromine in different solvents
(CHCl3, AcOH, AcOH–DMF, 5:1) using various sub-
strate-to-reagent ratios. The chlorination of benzo-
quinone imines Ia, Ic, Id, IIa, and IIb gave mainly the
corresponding 4-aroyl(arylsulfonyl)imino-3,5,6-tri-
chloro-2,6-diisopropylcyclohex-2-en-1-ones XIIa,
XIIc, XIId, XIIIa, and XIIIb. We failed to isolate
intermediate semiquinoid compounds, addition prod-
ucts of one chlorine molecule to quinone imines,
presumably because of their instability. Such com-
pounds, 4-aroyl(arylsulfonyl)imino-5,6-dichloro-2,6-
diisopropylcyclohex-2-en-1-ones, are analogs of
4-arylsulfonylimino-5,6-dichloro-2,6-dimethylcyclo-
hex-2-en-1-ones (products of addition of one chlorine
molecule to N-arylsulfonyl-2,6-dimethyl-1,4-benzo-
quinone imines), which were obtained previously only
as mixtures with the corresponding dehydrohalogena-
tion products, quinone imines [7]. 4-Arylsulfonyl-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 4 2008

AVDEENKO et al.
544
1
The structure of the isolated compounds was
not reflected in the H and 13C NMR spectra. Analysis
proved by the IR and H and 13C NMR spectra and
of the H and 13C NMR spectra of XIIa, XIIc, XIId,
1
1
1
elemental analyses. The H NMR spectra were re-
XIIIa, and XIIIb showed that different chemical shifts
of proton at the sp3-carbon atom and protons in the iso-
propyl groups may result from different spatial orienta-
tions of the isopropyl group and chlorine atom with
respect to each other; i.e., these compounds are dia-
stereoisomers B and D.
corded only for compounds having quinoid or semi-
1
quinoid structure. In the H NMR spectra of quinone
imines X and XI, the 5-H signal appeared as a broad-
ened singlet at δ 7.92–7.94 ppm. The 5-H proton in
the spectra of compounds VIII and IX resonated as
a broadened singlet at δ 6.61–6.64 ppm. According to
Differences in the steric structure of diastereo-
isomers B and D are clearly observed in the H NMR
1
the H and 13C NMR data, compounds XIIa, XIIc,
1
XIId, XIIIa, and XIIIb in solution exist as two
isomers. By repeated recrystallization of compound
XIId we succeeded in isolating its individual isomers
which had different melting points.
spectra where the 5-H protons and CH protons in the
isopropyl groups have different chemical shifts. In the
1H NMR spectrum of diastereoisomer B, the 5-H sig-
nal appears as a singlet at δ 5.00–5.03 (aroyl deriva-
tives XIIa, XIIc, and XIId) or 6.37–6.40 ppm (sul-
fonyl derivatives XIIIa and XIIIb); the CH proton in
the isopropyl group attached to C6 (sp3) resonates as
a multiplet at δ 2.61–2.76 (XII) or 2.72–2.82 ppm
(XIII). The other diastereoisomer D is characterized
by 5-H signal at δ 5.14–5.17 (XII) or 6.34–6.36 ppm
(XIII) and 6-CH signal at δ 2.31–2.44 (XII) or 2.25–
2.36 ppm (XIII).
In the 13C NMR spectra of diastereoisomers B and
D, the largest difference in chemical shifts is observed
for the sp3-hybridized C6 carbon atom bearing iso-
propyl group. The chemical shifts of C5 and C6 in
diastereoisomer B of XIId are δC 55.8 and 74.4 ppm,
respectively, and the chemical shifts of C5 and C6 in
diastereoisomer D of XIIa and XIId are δC 60.1, 59.7
and 83.9, 83.5 ppm, respectively. The differences in
the carbon chemical shifts (ΔδC) between diastereo-
isomers B and D are as follows, ppm: –8.98 (C6),
–3.89 (C5), 0.29 (C1), 0.61 (C2), 0.52 (C3), 0.95 (C4),
–6.40 (C7), –0.48 and –1.85 (C8, C9), 0.01 (C10), 0.13
and 0.21 (C11, C12), 0.13 (C13), 0.33 (C14), –0.15 (C15,
C19), –0.04 (C16, C18), –0.03 (C17); these values are
very consistent with spatial arrangement of carbon
atoms in structures B and D. In the 13C NMR spectrum
recorded without decoupling from protons, the C5 sig-
nal of diastereoisomer B of XIId appeared as a dou-
blet, and the C6 atom resonated as a multiplet; the C5
and C6 signals of diastereoisomer D were a doublet of
doublets and a multiplet, respectively. These spectral
data may be useful for determination of the steric
structure of halogen addition products at the C=C bond
in the quinoid ring.
Molecules of semiquinoid compounds XIIa, XIIc,
XIId, XIIIa, and XIIIb possess two chiral centers
(sp3-hybridized carbon atoms); therefore, they can
exist as four diastereoisomers or two couples of enan-
tiomers A/B and C/D. While analyzing the steric struc-
ture of these compounds, we assumed that the substit-
uent on the nitrogen atom is oriented trans with respect
to the halogen atom at the C=C bond (the latter is
characterized by a larger conformational volume than
that attached to sp3-hybridized carbon atom, C5), i.e.,
compounds XII and XIII are E isomers.
Cl
Cl
H
Pr-i
O
ArX
ArX
O
Pr-i
H
Cl
Cl
A
B
Cl
Pr-i
H
Cl
O
ArX
ArX
O
H
Cl
Cl
Pr-i
C
D
Provided that the E configuration persists and that
the cyclohexene ring inversion is slow on the NMR
1
time scale, The H NMR spectra should display four
sets of signals belonging to eight possible conformers
(enantiomer couples in achiral solvents give only one
1
13
set of signals in H and C NMR spectra). X-Ray dif-
fraction data for some structurally related compounds
showed disorder of sp3-hybridized carbon atoms with
different populations for enantiomeric structures like A
and B [8, 9], which may be responsible for their optical
activity [10]. As we already noted, such differences in
the steric structure of the compounds under study are
The structure of the isolated individual diastereo-
isomers of XIId was unambiguously proved by X-ray
analysis. The isomer with lower melting point was
shown to have structure B with equatorial orientation
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 4 2008

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... VII.
545
of the isopropyl group on C6 (Fig. 1). Correspondingly,
the high-melting isomer of XIId has structure D with
axial orientation of the isopropyl group on C6 (Fig. 2).
The semiquinoid ring in both stereoisomers has a con-
formation intermediate between half-chair and sofa
with the following puckering parameters [11]: S =
0.75, Θ = 28.8°, Ψ = 8.1° (B); S = 0.71, Θ = 39.2°, Ψ =
12.9° (D). The deviations of the C5 and C6 atoms from
the mean-square plane formed by the other ring carbon
atoms were, respectively, –0.13 and 0.54 Å (B) and
0.16 and –0.55 Å (D).
The substituent on the nitrogen atom occupies syn-
periplanar position with respect to the C4–C5 bond and
is almost orthogonal to the C4–N1 bond [torsion angles
C13N1C4C5 –6.3(3)° (B), 3.4(5)° (D) and C4N1C13O2
–87.0(3)° (B), 84.1(5)° (D)], presumably due to appre-
ciable repulsion between the H5 and C13 atoms
[shortened intramolecular contact H5 ···C13 2.52 (B),
2.55 Å (D) (2.87 Å)]. In addition, such orientation of
the substituent on the nitrogen atom is stabilized by the
attractive interaction H15 ···N1 2.58 (B), 2.53 Å (D)
(sum of van der Waals radii 2.67 Å). The nitro group is
almost coplanar to the aromatic ring plane [torsion
angle O4N2C17C18 14.3(3)° (B), 4.5(6)° (D)], which is
The isopropyl group on C2 is turned in such a way
that the C10–H bond in both stereoisomers appears in
a conformation close to synperiplanar [the torsion
angle C3C2C10H10 is 23° in B and –7.6° in D). This
conformation gives rise to steric repulsion between the
substituents at the endocyclic double bond {shortened
intramolecular contact H10···Cl1 2.60 (B), 2.51 Å (D);
sum of van der Waals radii 3.06 Å [12]}. The chlorine
atom on C5 in both stereoisomers occupies equatorial
position [torsion angle C3C4C5Cl2 –83.5(2)° (B),
–87.4(3)° (D)]. Stereoisomers B and D differ by orien-
tation of the substituents on C6: the chlorine atom in B
occupies axial position, and in D, equatorial [torsion
angle C2C1C6Cl3 –60.1(2)° (B) and 167.1(2)° (D)].
Correspondingly, the isopropyl group on C6 in B is
equatorial, and in D, axial: its arrangement with
respect to the C1–C6 bond is characterized by the
following torsion angles: C2C1C6C7 178.7(2)° (B),
–70.7(4)° (D) and C1C6C7H7 –53.3° (B), 59.8° (D).
The presence of fairly bulky substituents in the cyclo-
hexene ring and their mutual arrangement produce an
appreciable steric strain, as follows from the shortened
intramolecular contacts H5···C8 2.62 Å (B, D; sum of
van der Waals radii 2.87 Å); H5···H8a 2.21 (B), 2.07 Å
(D) (2.34 Å); H7···Cl2 2.84 Å (B) (3.07 Å), H7···C3
2.79 Å (D) (2.87 Å); H7···C4 2.67 Å (D) (2.87 Å);
H8b···Cl3 2.82 (B), 2.78 Å (D) (3.06 Å); H8c···C5 2.70
(B), 2.69 Å (D) (2.87 Å); H9a···Cl3 2.76 (B), 2.79 Å
(D) (3.06 Å); H9c···C1 2.77 (B), 2.63 Å (D) (2.87 Å);
Cl1
C10
C12
O3
C3
C16
C14
C15
C2
C11
N1
N2
C17
C4
Cl3
C1
O4
C18
C13
O2
O1
C9
C6
C19
C5
Cl2
C7
C8
Fig. 1. Structure of the molecule of 3,5,6-trichloro-2,6-diiso-
propyl-4-(4-nitrobenzoylimino)cyclohex-2-en-1-one (XIId,
diastereoisomer B with equatorial orientation of the iso-
propyl group on C6) according to the X-ray diffraction data.
C9
C8
C11
C7
C3
C2
C10
C12
Cl1
N1
O2
C4
C6
C1
Cl3
C13
C14
O1
C5
C19
Cl2
C15
C16
H
12a···C1 2.83 Å (B) (2.87 Å). Steric strain in isomer
C18
B with equatorial orientation of the 6-isopropyl group
induces twisting of the endocyclic double bond [tor-
sion angle C1C2C3C4 7.2(3)°] and makes the endo- and
exocyclic double bonds noncoplanar [torsion angles
O1C1C2C3 147.8(2)°, C2C3C4N1 167.7(2)°]. Isomer D
with axial orientation of the isopropyl group on C6 is
characterized by weaker steric strain, and only non-
coplanarity of the C=C and C=O bonds is observed
[torsion angle O1C1C2C3 163.4(4)°].
C17
N2
O4
O3
Fig. 2. Structure of the molecule of 3,5,6-trichloro-2,6-diiso-
propyl-4-(4-nitrobenzoylimino)cyclohex-2-en-1-one (XIId,
diastereoisomer G with axial orientation of the isopropyl
group on C6) according to the X-ray diffraction data.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 4 2008

AVDEENKO et al.
546
favored by the attractive interactions H16 ···O3 2.47
derivatives was impossible [13]. In the present work
we performed halogenation of 4-aroyloxyimino- and
4-arylsulfonyloxyimino-2,6-diisopropylcyclohexa-2,5-
dien-1-ones XIVa, XIVb, XVa, and XVb and ex-
amined the product mixtures with a view to detect Z
isomers and stereoisomers analogous to those formed
in the halogenation of quinone imines I and II. The
results are illustrated by Scheme 2.
(B), 2.40 Å (D) and H18···O4 2.42 (B), 2.44 Å (D).
Thus the structure of cyclohexene structures XIIa,
XIIc, XIId, XIIIa, and XIIIb suggests that the
chlorination of benzoquinone imines Ia, Ic, Id, IIa,
and IIb involves initial formation of the corresponding
carbocation, followed by trans- or cis-addition of the
second chlorine atom. The formation of carbocation is
favored by the presence of a bulky electron-donating
isopropyl group in the ortho-position with respect to
the carbonyl carbon atom.
Taking into account previously published data [2],
we presumed that halogenation of 1,4-benzoquinone
oxime ethers should give no stereoisomers with axially
oriented alkyl group (in this case, intermediate forma-
tion of carbocation is energetically less favorable than
the formation of halonium ion). The halogenation
products contained no compounds that could be
formed from intermediate carbocation [2].
Preferential formation of intermediate carbocation
and hence of stereoisomer D with axially oriented iso-
propyl group should also be favored by polar solvent.
We performed chlorination of compounds Id and
IIb in chloroform and acetic acid, and examined the
product structure before recrystallization. When the
reaction was carried out in chloroform, stereoisomer B
prevailed among the products: the B:D isomer ratio
was 84:16 for compound XIId and 60:40 for XIIIb.
In going to acetic acid, stereoisomer D became the
major product: the B:D isomer ratio was 22:78 for
compound XIId and 15:85 for XIIIb. These data
provide an additional support to the assumption that
halogenation of quinoid systems involves formation of
carbocationic species, which is favored by increased
solvent polarity.
The halogenation of XIVa, XIVb, XVa, and XVb
was carried out under severe conditions, in DMF at
elevated temperature, using a considerable excess of
halogen. Both chlorination and bromination of com-
pounds XIVa, XIVb, XVa, and XVb gave mixtures of
the corresponding E and Z isomers, the former prevail-
ing. The E/Z ratio for 4-(4-chlorobenzoyloxyimino)-
5,6-dichloro-2,6-diisopropylcyclohex-2-en-1-one
(XVIb) was 95:5, whereas 4-(4-methylbenzoyloxy-
imino)-5,6-dichloro-2,6-diisopropylcyclohex-2-en-1-
one (XVIa) was isolated only as E isomer. In the
halogenation of 4-arylsulfonyloxyimino-2,6-diiso-
propylcyclohexa-2,5-dien-1-ones XVa and XVb the
ratios E-XVIIIa/Z-XVIIIa, E-XIXa/Z-XIXa, and
E-XIXb/Z-XIXb were 92:8, 95:5, and 58:42, re-
spectively. Only the bromination of 4-(4-chloroben-
zoyloxyimino)cyclohexa-2,5-dien-1-one (XIVb) gave
a mixture of isomers E-XVIIb and Z-XVIIb at a ratio
of 32:68.
We previously reported [13] on the halogenation of
4-aroyl(arylsulfonyl)oxyimino-2,6-diisopropylcyclo-
hexa-2,5-dien-1-ones which afforded only E isomers
of the corresponding 4-aroyl(arylsulfonyl)oxyimino-
5,6-dihalo-2,6-diisopropylcyclohex-2-en-1-ones with
trans arrangement of the ArXO group and C=C bond
in the cyclohexene ring with respect to the C=N bond.
It was concluded that halogenation of quinone oxime
ethers is strictly syn-regioselective. The products were
Thus we can state that halogenation of 1,4-benzo-
quinone oxime ethers having two isopropyl groups in
positions 2 and 6 of the quinoid ring gives mainly the
corresponding syn-addition products.
1
analyzed by H NMR spectroscopy after recrystalliza-
tion. We failed to obtain products of more profound
halogenation, for dehydrohalogenation of the dihalo
Scheme 2.
O
O
O
O
Pr-i
Hlg
Pr-i
Hlg
Pr-i
Cl
i-Pr
Pr-i
i-Pr
i-Pr
i-Pr
Hlg2
Cl2
+
–HCl
Hlg
Hlg
Cl
Cl
N
N
N
N
OXAr
XIVa, XIVb, XVa, XVb
OXAr
ArXO
OXAr
E-XVIa, E-XVIb, E-XVIIb
E-XVIIIa, E-XIXa, E-XIXb
Z-XVIb, Z-XVIIb, Z-XVIIIa
Z-XIXa, Z-XIXb
E-XXa, E-XXb, E-XXIa
Ar = 4-MeC6H4 (a), 4-ClC6H4 (b); XIV, XVI, XVII, XX, X = CO; XV, XVIII, XIX, XXI, X = SO2; XVI, XVIII, Hlg = Cl;
XVII, XIX, X = Br.
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HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... VII.
547
Analysis of the chemical shifts of protons in the
cyclohexene ring and CH protons in the isopropyl
second halogen atom; in this case, the formation of
both trans- and cis-addition products is possible. The
relative contributions of these reaction paths are deter-
mined by the substrate structure and reaction condi-
tions. The carbocationic path is favored by the pres-
ence of electron-donating groups in the substrate
molecule and polar solvents. Halogenation of 1,4-ben-
zoquinone oxime ethers follows only the path involv-
ing formation of halonium ion, and the addition prod-
ucts are only the corresponding isomers with trans-
diaxial arrangement of the halogen atoms.
1
groups at sp3- and sp2-carbon atoms in the H NMR
spectra of compounds XVI–XXI, as well as the posi-
tion of signals from sp3-hybridized carbon atoms in the
13C NMR spectrum of E-XVIb, indicate that the halo-
gen atoms in both syn and anti isomers of XVI–XIX
occupy axial positions and are arranged trans with
respect to each other. Correspondingly, the isopropyl
group on C6 is equatorial. In other words, the halo-
genation of benzoquinone oxime ethers gives only one
stereoisomer like B with equatorial alkyl group. Unlike
benzoquinone imines, the formation of halogenation
products XIVa, XIVb, XVa, and XVb with only trans-
diaxial orientation of the halogen atoms is consistent
with the assumption that the process involves initial
formation of halonium ion.
EXPERIMENTAL
The IR spectra were recorded in KBr on a UR-20
spectrometer. The 1H and 13C NMR spectra were meas-
ured from solutions in CDCl3 on a Varian VXR-300
1
instrument (300 MHz for H); tetramethylsilane was
In the chlorination of benzoquinone oxime ethers
XIVa, XIVb, and XVa, the products were mixtures of
the corresponding 4-aroyl(arylsulfonyl)oxyimino-5,6-
dichloro-2,6-diisopropylcyclohex-2-en-1-ones and
4-aroyl(arylsulfonyl)oxyimino-3,5,6-trichloro-2,6-di-
isopropylcyclohex-2-en-1-ones XXa, XXb, and XXIa
used as reference. The reaction mixtures were analyzed
by thin-layer chromatography on Silufol UV-254
plates; samples were applied from solutions in chloro-
form, benzene–hexane (10:1) was used as eluent, and
spots were visualized under UV light.
1
X-Ray diffraction data for diastereoisomers of
compound XIId. Stereoisomer B. Monoclinic crystals,
C19H19Cl3N2O4. Unit cell parameters (20°C): a =
13.060(2), b = 7.148(1), c = 22.410(3) Å; β =
90.90(1)°, V = 2091.9(6) Å3; M 445.71; Z = 4; space
group P21/c; dcalc = 1.415 g/cm3; μ(MoKα) =
0.465 mm–1; F(000) = 920. The unit cell parameters
and intensities of 10205 reflections (4655 independent
reflections with Rint = 0.03) were measured on
an Xcalibur-3 diffractometer (MoKα irradaition, CCD
(Scheme 2). In keeping with the H NMR data, these
compounds exist as E isomers. Insofar as quinone
oximes are characterized by a high barrier to Z–E iso-
merization [14], compounds XXa, XXb, and XXIa
could be formed only via dehydrochlorination of the
Z isomers of XVIa, XVIb, and XVIIIa under severe
reaction conditions and subsequent chlorination of
intermediate 4-aroyl(arylsulfonyl)oxyimino-3-chloro-
2,6-diisopropylcyclohexa-2,5-dien-1-ones at the syn-
C=C bond.
detector, graphite monochromator, ω-scanning, 2θmax
=
We failed to effect dehydrohalogenation of 4-aroyl-
(arylsulfonyl)oxyimino-5,6-dichloro-2,6-diisopropyl-
cyclohex-2-en-1-ones in diethyl ether or chloroform in
the presence of triethylamine with a view to obtain
4-aroyl(arylsulfonyl)oxyimino-3-chloro-2,6-diiso-
propylcyclohexa-2,5-dien-1-ones and expose the latter
to further halogenation.
55°). The structure was solved by the direct method
using SHELXTL software package [15]. The positions
of hydrogen atoms were determined by difference syn-
thesis of electron density and were refined using riding
model (Uiso = n Ueq.; n = 1.5 for methyl hydrogen
atoms, n = 1.2 for the other hydrogen atoms). The
structure was refined with respect to F2 by full-matrix
least-squares procedure in anisotropic approximation
for non-hydrogen atoms; wR2 = 0.124 from 4612 re-
flections [R1 = 0.044 from 3481 reflections with F >
4σ(F), S = 1.125]. The coordinates of atoms and com-
plete sets of bond lengths and bond angles were de-
posited to the Cambridge Crystallographic Data Center
(entry no. CCDC 635555).
Our results led us to conclude that halogen addition
at the double C=C bond in the quinoid ring of N-sub-
stituted 1,4-benzoquinone imines can follow two dif-
ferent paths: (1) with intermediate formation of halo-
nium ion and addition of the second halogen atom
directly to the halonium ion; as a result, only trans-ad-
dition products with trans-diaxial arrangement of the
halogen atoms are obtained; and (2) through inter-
mediate carbocation with subsequent addition of the
St e re o i s o m e r D . M o n o c l i n i c c r y s t a l s,
C19H19Cl3N2O4. Unit cell parameters (20°C): a =
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 4 2008

AVDEENKO et al.
548
18.393(2), b = 9.217(1), c = 12.294(1) Å; β =
99.28(1)°; V = 2056.8(3) Å3; M 445.71; Z = 4; space
group P21/c; dcalc = 1.439 g/cm3; μ(MoKα) =
0.473 mm–1; F(000) = 920. The unit cell parameters
and intensities of 12978 reflections (3615 independent
reflections with Rint = 0.112) were measured
an Xcalibur-3 diffractometer (MoKα irradaition, CCD
amine according to the procedure described in [18];
their properties were given in [13].
4-(4-Chlorophenylsulfonyloxyimino)-2,6-diiso-
propylcyclohexa-2,5-dien-1-one (XVb). Yield 80%,
1
mp 118–120°C. H NMR spectrum, δ, ppm: 7.28 d
(1H, 3-H), 6.78 d (1H, 5-H), 3.01–3.16 m [2H,
CH(CH3)2], 1.10 d and 1.13 d (6H each, CH3), 7.58–
7.99 d.d (4H, Harom). Found, %: N 3.55, 3.62.
C18H20ClNO4S. Calculated, %: N 3.67.
detector, graphite monochromator, ω-scanning, 2θmax
=
50°). The structure was solved by the direct method
using SHELXTL software package [15]. The positions
of hydrogen atoms were determined by difference syn-
thesis of electron density and were refined using riding
model (Uiso = n Ueq.; n = 1.5 for methyl hydrogen
atoms, n = 1.2 for the other hydrogen atoms). The
structure was refined with respect to F2 by full-matrix
least-squares procedure in anisotropic approximation
for non-hydrogen atoms; wR2 = 0.226 from 3473 re-
flections [R1 = 0.075 from 2686 reflections with F >
4σ(F), S = 1.121]. The coordinates of atoms and com-
plete sets of bond lengths and bond angles were de-
posited to the Cambridge Crystallographic Data Center
(entry no. CCDC 635556).
Chlorination of 4-aroyl(arylsulfonyl)-2,6-diiso-
propylcyclohexa-2,5-dien-1-ones Ia, Ic, Id, IIa, and
IIb and 4-aroyl(arylsulfonyl)amino-2,6-diisopropyl-
phenols IIIa–IIId, IVa, and IVb (general procedure).
A stream of dry chlorine was passed at a flow rate of
15–20 ml/min at 25–30°C through a solution of
2 mmol of quinone imine Ia, Ic, Id, IIa, or IIb or
aminophenol IIIa–IIId, IVa, or IVb in 3 ml of chloro-
form, acetic acid, or DMF–AcOH (1:5). The substrate-
to-reagent ratio was controlled by weight and was
varied from 1:1 to 1:4. The mixture was left to stand
for 24 h, and the precipitate was filtered off and
recrystallized from acetic acid. The yields, melting
points, and elemental analyses are given below only
for those compounds which were isolated as individual
substances.
4-Aroylamino-2,6-diisopropylphenols IIIa–IIId
were synthesized by acylation of 4-amino-2,6-diiso-
propylphenol with the corresponding substituted ben-
zoyl chlorides in DMF–AcOH (1:5) in the presence of
sodium acetate according to the procedure described in
[16]. 4-Aroylimino-2,6-diisopropylcyclohexa-2,5-dien-
1-ones Ia, Ic, and Id were synthesized by oxidation of
the corresponding 4-aroylamino-2,6-diisopropyl-
phenols IIIa, IIIc, and IIId with lead tetraacetate in
acetic acid as reported in [16]. The properties of
quinone imines Ia, Ic, and Id and aminophenols IIIa–
IIId were given in [17]. 4-Arylsulfonylamino-2,6-di-
isopropylphenols IVa and IVb were prepared by reac-
tion of 4-amino-2,6-diisopropylphenol with the corre-
sponding arenesulfonyl chlorides in water in the pres-
ence of sodium hydrogen carbonate according to the
procedure described in [17]. 4-Arylsulfonylimino-2,6-
diisopropylcyclohexa-2,5-dien-1-ones IIa and IIb
were obtained by oxidation of 4-arylsulfonylamino-
2,6-diisopropylphenols IVa and IVb with lead tetra-
acetate in acetic acid [17]. The properties of quinone
imines IIa and IIb and aminophenols IVa and IVb
were given in [16]. 4-Aroyl(arylsulfonyl)oxyimino-
2,6-diisopropylcyclohexa-2,5-dien-1-ones XIVa,
XIVb, XVa, and XVb were synthesized by acylation
of 2,6-diisopropyl-4-iminocyclohexa-2,5-dien-1-one
with the corresponding benzoyl and arenesulfonyl
chlorides in diethyl ether in the presence of triethyl-
N-(3-Chloro-4-hydroxy-3,5-diisopropylphenyl)-
benzenesulfonamide (VIa). Yield 65%, mp 121–
122°C. Found, %: Cl 9.55, 9.78. C18H22ClNO3S. Cal-
culated, %: Cl 9.64.
N-(3-Chloro-4-hydroxy-3,5-diisopropylphenyl)-
4-methylbenzenesulfonamide (VIb). Yield 73%,
mp 122–123°C. Found, %: Cl 9. 35, 9. 43.
C19H24ClNO3S. Calculated, %: Cl 9.28.
4-Benzoylimino-3-chloro-2,6-diisopropylcyclo-
1
hexa-2,5-dien-1-one (VIIIa). H NMR spectrum, δ,
ppm: 6.61 d (1H, 5-H), 3.39–3.50 m (1H, 2-CH), 3.01–
3.11 m (1H, 6-CH), 1.39 d [6H, 2-CH(CH3)2], 1.11 d
[6H, 6-CH(CH3)2], 7.47–7.96 m (5H, Harom).
3-Chloro-2,6-diisopropyl-4-(4-nitrobenzoyl-
1
imino)cyclohexa-2,5-dien-1-one (VIIId). H NMR
spectrum, δ, ppm: 6.61 d (1H, 5-H), 3.52–3.62 m (1H,
2-CH), 3.00–3.08 m (1H, 6-CH), 1.35 d [6H,
2-CH(CH3)2], 1.07 d [6H, 6-CH(CH3)2], 8.13–8.38 d.d
(4H, Harom).
3-Chloro-2,6-diisopropyl-4-(phenylsulfonyl-
imino)cyclohexa-2,5-dien-1-one (Xa). Yield 85%,
1
mp 70–72°C. H NMR spectrum, δ, ppm: 7.92 br.s
(1H, 5-H), 3.47–3.56 m (1H, 2-CH), 3.04–3.13 m
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 4 2008

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... VII.
549
1
(1H, 6-CH), 1.30 d [6H, 2-CH(CH3)2], 1.19 d [6H,
6-CH(CH3)2], 7.56–8.07 m (5H, Harom). Found, %:
Cl 9.55, 9.74. C18H20ClNO3S. Calculated, %: Cl 9.69.
Isomer D. Yield 15%, mp 190–192°C. H NMR
spectrum, δ, ppm: 5.17 s (1H, 5-H), 3.47–3.56 m (1H,
2-CH), 2.35–2.44 m (1H, 6-CH), 1.27–1.41 d.d [6H,
2-CH(CH3)2], 0.92–1.20 d.d [6H, 6-CH(CH3)2], 8.12–
8.37 d.d (4H, C6H4). 13C NMR spectrum, δC, ppm:
187.23 (C1); 175.51 (NC=O); 157.20 (C4); 150.99
(C4′); 150.49 (C2); 139.41 (C3); 136.09 (C1′); 130.61
(C2′); 123.97 (C3′); 83.47 (C6); 59.74 (C5); 35.61, 32.09
(CHMe2); 20.24, 18.67, 18,30, 17.05 (Me). Found,
%: Cl 23.22, 23.47. C19H19Cl3N2O4. Calculated, %:
Cl 23.86.
3-Chloro-2,6-diisopropyl-4-(4-methylphenylsul-
fonylimino)cyclohexa-2,5-dien-1-one (Xb). Yield
1
80%, mp 128–131°C. H NMR spectrum, δ, ppm:
7.91 br.s (1H, 5-H), 3.46–3.54 m (1H, 2-CH), 3.05–
3.14 m (1H, 6-CH), 1.29 d [6H, 2-CH(CH3)2], 1.18 d
[6H, 6-CH(CH3)2], 7.37–7.93 d.d (4H, C6H4), 2.46 s
(3H, CH3C6H4). Found, %: Cl 9. 25, 9. 41.
C19H22ClNO3S. Calculated, %: Cl 9.33.
3,5,6-Trichloro-2,6-diisopropyl-4-(phenylsul-
fonylimino)cyclohex-2-en-1-one (XIIIa, isomer B).
1H NMR spectrum, δ, ppm: 6.37 s (1H, 5-H), 3.35–
3.46 m (1H, 2-CH), 2.72–2.82 m (1H, 6-CH), 1.10–
1.36 m (12H, CH3), 7.56–8.08 m (5H, Harom).
4-Benzoylimino-3,5,6-trichloro-2,6-diisopropyl-
cyclohex-2-en-1-one (XIIa, isomer B). 1H NMR spec-
trum, δ, ppm: 5.00 s (1H, 5-H), 3.36–3.48 m (1H,
2-CH), 2.61–2.74 m (1H, 6-CH), 1.26–1.39 d.d [6H,
2-CH(CH3)2], 0.92–1.11 d.d [6H, 6-CH(CH3)2], 7.43–
7.98 m (5H, Harom).
1
Isomer D. Yield 77%, mp 127–128°C. H NMR
1
Isomer D. Yield 30%, mp 139–140°C. H NMR
spectrum, δ, ppm: 6.34 s (1H, 5-H), 3.41–3.55 m (1H,
2-CH), 2.25–2.36 m (1H, 6-CH), 0.90–1.37 m (12H,
CH3), 7.56–8.08 m (5H, Harom). Found, %: Cl 23.95,
24.28. C18H20Cl3NO3S. Calculated, %: Cl 24.35.
spectrum, δ, ppm: 5.14 s (1H, 5-H), 3.45–3.59 m (1H,
2-CH), 2.31–2.44 m (1H, 6-CH), 1.27–1.40 d.d [6H,
2-CH(CH3)2], 0.89–1.13 d.d [6H, 6-CH(CH3)2], 7.48–
7.96 m (5H, Harom). 13C NMR spectrum, δC, ppm:
187.53 (C1); 177.70 (NC=O); 155.91 (C4); 149.50
(C2); 140.34 (C3); 134.31 (C4′); 131.20 (C1′); 129.62
(C2′); 128.84 (C3′); 83.78 (C6); 59.91 (C5); 35.61, 31.92
(CHMe2); 20.24, 18.75, 18.38, 17.12 (Me). Found,
%: Cl 26.73, 26.84. C19H22ClNO3S. Calculated, %:
Cl 26.54.
3,5,6-Trichloro-2,6-diisopropyl-4-(4-methyl-
phenylsulfonylimino)cyclohex-2-en-1-one (XIIIb).
1H NMR spectrum, δ, ppm: isomer B: 6.40 s (1H,
5-H), 3.36–3.45 m (1H, 2-CH), 2.73–2.81 m (1H,
6-CH), 1.10–1.35 m [12H, CH(CH3)2], 7.36–7.95 d.d
(4H, C6H4), 2.46 s (3H, CH3C6H4); isomer D: 6.36 s
(1H, 5-H), 3.43–3.53 m (1H, 2-CH), 2.25–2.34 m (1H,
6-CH), 0.89–1.35 m [12H, CH(CH3)2], 7.38–7.95 d.d
(4H, C6H4), 2.47 s (3H, CH3C6H4).
3,5,6-Trichloro-2,6-diisopropyl-4-(4-methoxy-
1
benzoylimino)cyclohex-2-en-1-one (XIIc). H NMR
spectrum, δ, ppm: isomer B: 5.00 s (1H, 5-H), 3.40–
3.50 m (1H, 2-CH), 2.64–2.76 m (1H, 6-CH), 1.23–
1.40 d.d [6H, 2-CH(CH3)2], 0.89–1.12 d.d [6H,
6-CH(CH3)2], 3.88 s (3H, CH3O), 7.91–8.09 d.d (4H,
The IR spectra of semiquinoid compounds XIIa,
XIIc, XIId, XIIIa, and XIIIb contained absorption
bands in the regions 1720–1700 (C1=O), 1630–1610
(C=N), and 1678–1660 cm–1 (NC=O, XII).
Harom); isomer D: 5.15 s (1H, 5-H), 3.45–3.55 m (1H,
Bromination of 4-aroyl(arylsulfonyl)amino-2,6-
diisopropylphenols IIIa, IIIb, IVa, and IVb (general
procedure). Aminophenol IIIa, IIIb, IVa, or IVb,
2 mmol, was dissolved in 3 ml of chloroform, acetic
acid, DMF, or DMF–AcOH (1:5), and a solution of
bromine in the same solvent was added dropwise to
attain a substrate-to-bromine ratio of 1:1, 1:3, or 1:5.
We succeeded in isolating products when the reaction
was performed in chloroform with an equimolar
amount of bromine. In the other cases, noncrystal-
lizable oily materials were formed, which contained
several components (according to the TLC data). The
product was filtered off, washed with acetic acid and
recrystallized from acetic acid. The structure of com-
pounds Va, Vb, VIIa, and VIIb was proved by the
2-CH), 2.33–2.42 m (1H, 6-CH), 1.25–1.40 d.d [6H,
2-CH(CH3)2], 0.91–1.15 d.d [6H, 6-CH(CH3)2], 3.98 s
(3H, CH3O), 7.91–8.09 d.d (4H, Harom).
3,5,6-Trichloro-2,6-diisopropyl-4-(4-nitroben-
zoylimino)cyclohex-2-en-1-one (XIId, isomer B).
1
Yield 82%, mp 121–123°C. H NMR spectrum, δ,
ppm: 5.03 s (1H, 5-H), 3.39–3.49 m (1H, 2-CH), 2.65–
2.76 m (1H, 6-CH), 1.24–1.40 d.d [6H, 2-CH(CH3)2],
0.94–1.14 d.d [6H, 6-CH(CH3)2], 8.13–8.36 d.d (4H,
H
arom). 13C NMR spectrum, δC, ppm: 187.21 (C1);
175.18 (NC=O); 156.21 (C4); 151.40 (C2); 150.83
(C4′); 136.79 (C3); 136.63 (C1′); 130.48 (C2′); 123.88
(C3′); 74.38 (C6); 55.85 (C5); 32.03, 29.14 (CHMe2);
20.32, 18.48, 18.16, 15.16 (Me). Found, %: Cl 23.40,
23.69. C19H19Cl3N2O4. Calculated, %: Cl 23.86.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 4 2008

AVDEENKO et al.
550
1H NMR data for the corresponding quinone imines
IXa, IXb, XIa, and XIb and elemental analyses.
(1H, 5-H), 3.47–3.57 m (1H, 2-CH), 3.04–3.13 m
(1H, 6-CH), 1.30 d [6H, 2-CH(CH3)2], 1.19 d [6H,
6-CH(CH3)2], 7.56–8.07 m (5H, Harom). Found, %:
Br 19.10, 19.52. C18H20BrNO3S. Calculated, %:
Br 19.47.
4-Benzoylamino-3-bromo-2,6-diisopropylphenol
(Va). Yield 68%, mp 158–160°C. Found, %: Br 20.86,
21.02. C19H22BrNO2. Calculated, %: Br 21.23.
3-Bromo-2,6-diisopropyl-4-(4-methylphenyl-
3-Bromo-2,6-diisopropyl-4-(4-methylbenzoyl-
amino)phenol (Vb). Yield 87%, mp 175–176°C.
Found, %: Br 21.10, 21.17. C20H24BrNO2. Calculated,
%: Br 20.47.
sulfonylimino)cyclohexa-2,5-dien-1-one (XIb). Yield
1
83%, mp 136–138°C. H NMR spectrum, δ, ppm:
7.94 br.s (1H, 5-H), 3.46–3.56 m (1H, 2-CH), 3.05–
3.14 m (1H, 6-CH), 1.29 d [6H, 2-CH(CH3)2], 1.18 d
[6H, 6-CH(CH3)2], 7.37–7.94 d.d (4H, C6H4), 2.46 s
(3H, CH3C6H4). Found, %: Br 18.73, 18.99.
C19H22BrNO3S. Calculated, %: Br 18.83.
3-Bromo-2,6-diisopropyl-4-(phenylsulfonyl-
amino)phenol (VIIa). Yield 90%, mp 160–164°C.
Found, %: Br 19.05, 19.17. C18H22BrNO3S. Calculat-
ed, %: Br 19.38.
The IR spectra of quinone imines IXa, IXb, XIa,
and XIb contained absorption bands in the regions
1660–1645 (C1=O), 1620–1605 (C=N), and 1690–
1670 cm–1 (NC=O, IX).
3-Bromo-2,6-diisopropyl-4-(4-methylphenylsul-
fonylamino)phenol (VIIb). Yield 89%, mp 136–
138°C. Found, %: Br 18.30, 18.64. C19H24BrNO3S.
Calculated, %: Br 18.74.
Chlorination of 4-aroyl(arylsulfonyl)oxyimino-
2,6-diisopropylcyclohexa-2,5-dien-1-ones XIVa,
XIVb, XVa, and XVb (general procedure). Quinone
oxime ether XIVa, XIVb, XVa, or XVb, 2 mmol, was
dissolved in dimethylformamide, and a stream of dry
chlorine was passed through the solution at a flow
rate of 15–20 ml/min until complete saturation. The
mixture was diluted with 10–15 ml of water, and the
precipitate was filtered off and recrystallized from
acetic acid.
4-Aroyl(arylsulfonyl)imino-3-bromo-2,6-diiso-
propylcyclohexa-2,5-dien-1-ones IXa, IXb, XIa,
and XIb (general procedure). Lead tetraacetate,
0.88 mmol, was added at room temperature to a mix-
ture of 0.8 mmol of aminophenol Va, Vb, VIIa, or
VIIb in 3 ml of acetic acid, and the mixture was
stirred. Initial aminophenols dissolved, the solution
warmed up and turned yellow, and a solid separated.
The mixture was cooled, 2–3 drops of ethylene glycol
were added under stirring, and the yellow precipitate
was filtered off, washed with acetic acid, and recrystal-
lized from acetic acid.
Cyclohexene derivatives E-XVIa, E-XVIb, and
E-XVIIIa were identical to those reported in [11].
(Z)-5,6-Dichloro-2,6-diisopropyl-4-(4-methyl-
benzoyloxyimino)cyclohex-2-en-1-one (Z-XVIa).
1H NMR spectrum, δ, ppm: 7.20 q (1H, 3-H), 5.31 d
(1H, 5-H, J3,5 = 2.1 Hz), 3.01–3.11 m (1H, 2-CH),
2.74–2.88 m (1H, 6-CH), 1.16–1.22 d.d [6H,
2-CH(CH3)2], 1.08–1.14 d.d [6H, 6-CH(CH3)2], 7.32–
8.00 d.d (4H, C6H4), 2.46 s (3H, CH3C6H4).
4-Benzoylimino-3-bromo-2,6-diisopropylcyclo-
hexa-2,5-dien-1-one (IXa). Yield 78%, mp 95–96°C.
1H NMR spectrum, δ, ppm: 6.64 d (1H, 5-H), 3.53–
3.62 m (1H, 2-CH), 2.95–3.04 m (1H, 6-CH), 1.35 d
[6H, 2-CH(CH3)2], 1.02 d [6H, 6-CH(CH3)2], 7.47–
7.96 m (5H, Harom). Found, %: Br 20.95, 21.32.
C19H20BrNO2. Calculated, %: Br 21.35.
5,6-Dichloro-4-(4-chlorobenzoyloxyimino)-2,6-
diisopropylcyclohex-2-en-1-one (XVIb, E isomer).
13C NMR spectrum, δC, ppm: 190.13 (C1); 187.95
(NC=O); 157.23 (C4); 151.44 (C2); 140.64 (C4′);
131.09, 129.26 (C2′, C3′); 126.33 (C1′); 126.23 (C3);
72.70 (C6); 51.55 (C5); 29.38, 28.21 (CHMe2); 21.07,
20.29, 18.92, 15.67 (Me).
3-Bromo-2,6-diisopropyl-4-(4-methylbenzoyl-
imino)cyclohexa-2,5-dien-1-one (IXb). Yield 90%,
1
mp 104–106°C. H NMR spectrum, δ, ppm: 6.63 d
(1H, 5-H), 3.53–3.62 m (1H, 2-CH), 2.95–3.04 m
(1H, 6-CH), 1.35 d [6H, 2-CH(CH3)2], 1.01 d [6H,
6-CH(CH3)2], 7.28–7.84 d.d (4H, C6H4), 2.44 s (3H,
CH3C6H4). Found, %: Br 20.65, 20.98. C20H22BrNO2.
Calculated, %: Br 20.58.
1
Z Isomer. H NMR spectrum, δ, ppm: 7.21 q (1H,
3-H), 5.30 d (1H, 5-H, J3,5 = 2.1 Hz), 3.00–3.13 m
(1H, 2-CH), 2.74–2.88 m (1H, 6-CH), 1.17–1.23 d.d
[6H, 2-CH(CH3)2], 1.09–1.15 d.d [6H, 6-CH(CH3)2],
7.50–8.06 d.d (4H, C6H4).
3-Bromo-2,6-diisopropyl-4-(phenylsulfonyl-
imino)cyclohexa-2,5-dien-1-one (XIa). Yield 76%,
1
mp 104–106°C. H NMR spectrum, δ, ppm: 7.96 br.s
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HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... VII.
551
(1H, 5-H, J3,5 = 1.8 Hz), 3.05–3.19 m (1H, 2-CH),
2.45–2.55 m (1H, 6-CH), 1.15–1.20 d.d [6H,
2-CH(CH3)2], 1.09–1.12 d.d [6H, 6-CH(CH3)2], 7.51–
8.07 d.d (4H, C6H4).
5,6-Dichloro-2,6-diisopropyl-4-(4-methylphenyl-
sulfonyloxyimino)cyclohex-2-en-1-one (XVIIIa,
E isomer). 13C NMR spectrum, δC, ppm: 189.93 (C1);
157.34 (C4); 151.42 (C2); 145.77 (C4′); 131.69 (C1′);
129.81, 128.91 (C2′, C3′); 125.16 (C3); 72.59 (C6);
50.92 (C5); 29.36, 28.16 (CHMe2); 21.70, 20.99,
20.17, 18.95, 15.77 (Me).
(Z)-5,6-Dibromo-2,6-diisopropyl-4-(4-methyl-
phenylsulfonyloxyimino)cyclohex-2-en-1-one
1
(Z-XIXa). H NMR spectrum, δ, ppm: 6.96 q (1H,
1
3-H), 5.13 d (1H, 5-H, J3,5 = 1.5 Hz), 2.95–3.06 m
(1H, 2-CH), 2.35–2.44 m (1H, 6-CH), 1.11–1.20 d.d
[6H, 2-CH(CH3)2], 1.02–1.07 d.d [6H, 6-CH(CH3)2],
7.36–7.92 d.d (4H, C6H4), 2.46 s (3H, CH3C6H4).
Z Isomer. H NMR spectrum, δ, ppm: 7.02 q (1H,
3-H), 4.93 d (1H, 5-H, J3,5 = 1.8 Hz), 2.94–3.02 m
(1H, 2-CH), 2.66–2.75 m (1H, 6-CH), 1.11–1.16 d.d
[6H, 2-CH(CH3)2], 1.01–1.09 d.d [6H, 6-CH(CH3)2],
7.36–7.91 d.d (4H, C6H4), 2.46 s (3H, CH3C6H4).
(E)-5,6-Dibromo-4-(4-chlorophenylsulfonyl-
oxyimino)-2,6-diisopropylcyclohex-2-en-1-one
(E-XIXb). H NMR spectrum, δ, ppm: 6.47 q (1H,
3-H), 5.56 d (1H, 5-H, J3,5 = 1.8 Hz), 2.96–3.06 m
(1H, 2-CH), 2.36–2.46 m (1H, 6-CH), 1.13–1.19 d.d
[6H, 2-CH(CH3)2], 1.02–1.08 d.d [6H, 6-CH(CH3)2],
7.54–7.98 d.d (4H, C6H4).
(E)-3,5,6-Trichloro-2,6-diisopropyl-4-(4-methyl-
benzoyloxyimino)cyclohex-2-en-1-one (E-XXa).
Yield 83%, mp 136–138°C. H NMR spectrum, δ,
ppm: 5.65 s (1H, 5-H), 3.42–3.52 m (1H, 2-CH), 2.76–
2.84 m (1H, 6-CH), 1.21–1.38 d.d [6H, 2-CH(CH3)2],
1.09–1.18 d.d [6H, 6-CH(CH3)2], 7.32–8.00 d.d (4H,
C6H4), 2.46 s (3H, CH3C6H4). Found, %: Cl 24.40,
24.61. C20H22Cl3NO3. Calculated, %: Cl 24.69.
1
1
(Z)-5,6-Dibromo-4-(4-chlorophenylsulfonyl-
oxyimino)-2,6-diisopropylcyclohex-2-en-1-one
1
(Z-XIXb). H NMR spectrum, δ, ppm: 6.98 q (1H,
(E)-3,5,6-Trichloro-4-(4-chlorobenzoyloxyimino)-
2,6-diisopropylcyclohex-2-en-1-one (E-XXb).
1H NMR spectrum, δ, ppm: 5.61 s (1H, 5-H), 3.42–
3.52 m (1H, 2-CH), 2.74–2.87 m (1H, 6-CH), 1.23–
1.38 d.d [6H, 2-CH(CH3)2], 1.09–1.17 d.d [6H,
6-CH(CH3)2], 7.51–8.06 d.d (4H, C6H4).
3-H), 5.12 d (1H, 5-H, J3,5 = 1.8 Hz), 3.05–3.19 m
(1H, 2-CH), 2.45–2.55 m (1H, 6-CH), 1.15–1.20 d.d
[6H, 2-CH(CH3)2], 1.02–1.06 d.d [6H, 6-CH(CH3)2],
7.51–8.07 d.d (4H, C6H4).
REFERENCES
(E)-3,5,6-Trichloro-2,6-diisopropyl-4-(4-methyl-
1. Avdeenko, A.P., Konovalova, S.A., and Ludchenko, O.N.,
phenylsulfonyloxyimino)cyclohex-2-en-1-one
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1
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5-H), 3.41–3.52 m (1H, 2-CH), 2.66–2.75 m (1H,
6-CH), 1.18–1.25 d.d [6H, 2-CH(CH3)2], 1.05–
1.10 d.d [6H, 6-CH(CH3)2], 7.36–7.99 d.d (4H, C6H4),
2.46 s (3H, CH3C6H4).
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XVa, and XVb (general procedure). A solution of
bromine in DMF was added dropwise under stirring to
a solution of 2 mmol of quinone oxime ether XIVb,
XVa, or XVb in 3 ml of DMF until a substrate-to-
bromine ratio of 1:5 or 1:8 was attained. The mixture
was diluted with 10–15 ml of water, and the crystalline
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The properties of compounds E-XVIIb and
E-XIXa were consistent with the data reported in [11].
(Z)-5,6-Dibromo-4-(4-chlorobenzoyloxyimino)-
2,6-diisopropylcyclohex-2-en-1-one (Z-XVIIb).
1H NMR spectrum, δ, ppm: 7.17 q (1H, 3-H), 5.51 d
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