Halogenation of n-substituted p-quinone monoimines and p-quinone monooxime esters: VIII. Halogenation of N-aroyl(arylsulfonyl)-2,6-di-tert-butyl-1,4- benzoquinone monoimines and their reduced forms

Article abstract of DOI:10.1134/S1070428008060055

Chlorination of N-aroyl(arylsulfonyl)-2,6-di-tert-butyl-1,4-benzoquinone imines gave Z and E isomers of 4-arylsulfonylimino-2,6-di-tert-butyl-5,6- dichlorocyclohex-2-en-1-ones and Z isomers of 4-aroyl-(arylsulfonyl)imino-2,6- di-tert-butyl-5,5,6-trichloro

Full text of DOI:10.1134/S1070428008060055

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2008, Vol. 44, No. 6, pp. 807–813. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © A.P. Avdeenko, V.V. Pirozhenko, O.V. Shishkin, G.V. Palamarchuk, R.I. Zubatyuk, S.A. Konovalova, O.N. Ludchenko, 2008,
published in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 6, pp. 818–824.
Halogenation of N-Substituted p-Quinone Monoimines
and p-Quinone Monooxime Esters: VIII.* Halogenation
of N-Aroyl(arylsulfonyl)-2,6-di-tert-butyl-1,4-benzoquinone
Monoimines and Their Reduced Forms
A. P. Avdeenkoa, V. V. Pirozhenkob, O. V. Shishkinc, G. V. Palamarchukc, R. I. Zubatyukc,
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, ul. Murmanskaya 5, Kiev, 02660 Ukraine
c Institute of Single Crystals, National Academy of Sciences of Ukraine, Kharkov, Ukraine
Received March 10, 2007
Abstract—Chlorination of N-aroyl(arylsulfonyl)-2,6-di-tert-butyl-1,4-benzoquinone imines gave Z and E
isomers of 4-arylsulfonylimino-2,6-di-tert-butyl-5,6-dichlorocyclohex-2-en-1-ones and Z isomers of 4-aroyl-
(arylsulfonyl)imino-2,6-di-tert-butyl-5,5,6-trichlorocyclohex-2-en-1-ones, in which the tert-butyl group on the
sp3-hybridized carbon atom occupies exclusively the axial position. The formation of Z/E-isomeric structures is
related to configurational stability of the chlorination products. The chlorination of 4-aroylamino-2,6-di-tert-
butylphenols was found to be accompanied by replacement of one tert-butyl group by chlorine atom with
formation of 4-aroylimino-6-tert-butyl-2,3,5,6-tetrachlorocyclohex-2-en-1-ones.
DOI: 10.1134/S1070428008060055
The presence of donor isopropyl groups in positions
2 and 6 of 1,4-benzoquinone monoimines was shown
to favor formation of carbocationic intermediate in the
halogenation of these compounds, making both trans
and cis addition of the second halogen atom possible
[1]. As a result, cyclohexene structures were obtained,
in which the isopropyl group at the sp3-hybridized car-
bon atom occupies equatorial (trans addition) or axial
position (cis addition); such a behavior was not
reported previously for these compounds. Addition of
a halogen molecule at the double C=C bond in the
quinoid ring usually gives products with trans-diaxial
orientation of the halogen atoms. It might be expected
that introduction of a stronger electron-donating and
bulkier tert-butyl group into positions 2 and 6 of the
quinoid ring will favor formation of intermediate carbo-
cation to even greater extent, so that the tert-butyl
group in the adduct will occupy only the axial position.
butyl-1,4-benzoquinone imines I and II and their
reduction products III and IV. It should be noted that
both N-aroyl- and N-arylsulfonyl-2,6-di-tert-butyl-1,4-
benzoquinone imines I and II in solution undergo Z/E
isomerization and that the corresponding activation
barriers are considerably different. For example, the
Gibbs energy of activation ΔG≠298 for the isomeriza-
tion of N-aroyl-1,4-benzoquinone imines ranges from
44 to 46 kJ/mol [2], while the ΔG≠298 value for N-aryl-
sulfonyl-1,4-benzoquinone imines varies from 65 to
1
80 kJ/mol [3]. This is also reflected in the H NMR
spectra of these compounds: the 3-H and 5-H signals
in the spectra of Ib and Ic give one broadened singlet
in a strong field, while signals from analogous protons
in arylsulfonyl derivatives IIa and IIc appear as dou-
blets, and the difference in their chemical shifts Δδ is
about 1.2 ppm. Taking into account that Z/E isomeriza-
tion could essentially affect the halogenation of N-aryl-
sulfonyl-1,4-benzoquinone imines [4], some differ-
ences in the behavior of compounds I and II under
halogenation conditions might be expected.
In order to verify this assumption, we examined
halogenation of N-aroyl(arylsulfonyl)-2,6-di-tert-
* For communication VII, see [1].
807

AVDEENKO et al.
808
Scheme 1.
O
N
O
N
t-Bu
Cl
t-Bu
Bu-t
Bu-t
Cl
+
Cl
Cl
O
N
t-Bu
Bu-t
SO2Ar
ArSO2
Cl2
(Z)-Va, (Z)-Vc
(E)-Va, (E)-Vc
O
N
OH
t-Bu
Bu-t
t-Bu
Bu-t
XAr
Cl
Cl2
Ib, Ic, IIa, IIc
Cl
Cl
HN
XAr
XAr
(Z)-VIa–(Z)-VIc, (Z)-VIIa
IIIa–IIIc, IVa, IVc
O
t-Bu
Cl
Cl
Cl
Cl
N
ArCO
(E)-VIIIa–(E)-VIIIc
Ar = Ph (a), 4-MeC6H4 (b), 4-O2NC6H4 (c); I, III, VI, X = CO; II, IV, VII, X = SO2.
We found that compounds I–IV do not undergo
bromination with molecular bromine. A probable
reason is the large size of both tert-butyl group and
bromine atom. In the reactions with I and IV we
isolated from the reaction mixture 2,6-di-tert-butyl-
1,4-benzoquinone, whereas compounds II and III re-
mained intact.
pound Va was isolated only as a mixture with VIIa.
These data indicate high reactivity of the correspond-
ing cyclohexene structures.
1
According to the H NMR data, 4-arylsulfonyl-
imino-2,6-di-tert-butyl-5,6-dichlorocyclohex-2-en-1-
ones Va and Vc in solution exist as mixtures of Z and
E isomers at a ratio of 1:1. Their spectra contain
double sets of signals from 3-H and 5-H and protons in
The chlorination of compounds I–IV with gaseous
chlorine was performed in acetic acid and acetic acid–
dimethylformamide mixture (5:1) at different sub-
strate-to-reagent ratios. Products of addition of one
chlorine molecule, 4-arylsulfonylimino-2,6-di-tert-
butyl-5,6-dichlorocyclohex-2-en-1-ones Va and Vc
were obtained only from arylsulfonyl derivatives IIa
and IIc (Scheme 1). As noted above, N-aroyl deriva-
tives are characterized by considerably lower barrier to
Z/E isomerization, whereas the ability of cyclohexene
structures to undergo dehydrochlorination is strongly
related to their isomer composition: dehydrochlorina-
tion of the Z isomers occurs more readily [4]. There-
fore, we failed to isolate products of addition of one
chlorine molecule to quinone imines Ib and Ic. Obvi-
ously, their fast dehydrochlorination is followed by
addition of the second chlorine molecule. Compound
Vc was isolated as individual substance, and com-
13
the tert-butyl groups. The C NMR spectra of Va and
Vc also displayed double sets of signals. The chemical
shift of C5 strongly depends on the orientation of the
substituent on the nitrogen atom. E Isomers of V (trans
orientation of the arylsulfonyl group with respect to the
double C=C bond) are characterized by more upfield
position of the C5 signal (δC 58.97 ppm), while the C5
signal of the Z isomers is located at δC 67.16 ppm. The
signal from the sp3-hybridized C6 carbon atom appears
in a fairly weak field, at δC 86.48 and 86.90 ppm for
the E and Z isomers, respectively. We previously
revealed a relation between the chemical shift of the
sp3-C6 atom and orientation of the substituent attached
thereto in 4-aroyl(arylsulfonyl)imino-3,5,6-trichloro-
2,6-diisopropylcyclohex-2-en-1-ones (the C6 signal is
displaced considerably downfield if the isopropyl
group occupies the axial position) [1]. Therefore, axial
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 6 2008

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... VIII.
809
ethyl(diisopropyl)amine and N-chlorosuccinimide in
orientation of the tert-butyl group in molecules V was
assumed.
tetrahydrofuran [5].
The structure of cyclohexenone derivatives VIa and
VIIIa was unambiguously proved by X-ray analysis of
their single crystals (Figs. 1, 2). The results indicated
considerable steric strain in their molecules due to the
presence of bulky substituents. Structure VIa is char-
acterized by the following short intramolecular con-
tacts: Cl2 ···C12 3.18, C4 ···C13 2.99, C4 ···H13c 2.48,
C3 · · · H10a 2.73, C3 · · · H10c 2.74, C3 · · · H13c 2.69,
C10 ···H3 2.41, H3 ···H10a 2.25, and H3 ···H10c 2.15 Å;
the sums of the corresponding van der Waals radii [6]
are Cl···C 3.61, C···C 3.42, C···H 2.87, and H···H
2.25 Å. As a result, some bond angles are distorted.
The bond angles C3C2C7 [122.9(2)°] and C6C5Cl2
[114.3(2)°] are larger than C1C2C7 [118.6(2)°] and
C4C5Cl2 [110.9(2)°]. In addition, the bond angles
C6C11C13 and C6C11C12 are increased to 112.7(2) and
113.5(2)°. respectively, as compared to the other bond
angles at the quaternary carbon atoms in the tert-butyl
groups [107.3(2)–111.2(2)°]. Steric strain in molecule
VIa also induces appreciable extension of the C1–C6
[1.544(3) Å] and C6–C11 bonds [1.550(3) Å]; the corre-
sponding average values are 1.51 [7] and 1.53 Å,
respectively. Difference in the lengths of the chem-
ically equivalent C5–Cl2 [1.762(2) Å] and C5–Cl3
bonds [1.800(2) Å] should also be noted. The C6–Cl1
bond length is intermediate between the above values,
1.789(2) Å.
Cl
Cl
H
H
ArSO2
N
O
ArSO2
N
O
Cl
Bu-t
Cl
Bu-t
(Z)-V
(E)-V
By chlorination of quinone imines Ib and Ic and
aminophenols IIIa, IIIc, and IVa at a substrate-to-
chlorine ratio of 1:3 to 1:4.5 we obtained 4-aroyl-
(arylsulfonyl)imino-2,6-di-tert-butyl-5,5,6-trichloro-
cyclohex-2-en-1-ones VIa–VIc and VIIa whose struc-
1
ture was confirmed by analysis of their H NMR
spectra. Compounds VIa–VIc displayed the 3-H signal
at δ 6.83–6.84 ppm, while the chemical shift of 3-H in
VIIa was 8.17 ppm. These data unambiguously in-
dicate location of the 3-H proton at the double C=C
bond. In the 13C NMR spectra of the products, the
sp3-hybridized C5 carbon atom resonated at δC 92.85–
93.19 ppm, and the C6 signal was located in the region
δC 94.34–95.07 ppm. We believe that the downfield
position of the C6 signal indicates axial orientation of
the tert-butyl group attached thereto.
Cl
Cl
Cl
H
ArX
N
O
ArCO
N
O
Cl
Bu-t
(Z)-VI, (Z)-VII
Cl
Bu-t
The axial orientation of the tert-butyl group in mole-
cule VIIIa gives rise to short intramolecular contacts
Cl4···H10c 2.67 Å (the sum of the corresponding van
der Waals radii is 3.06 Å) and Cl4 · · · H8c 2.76 Å
(3.06 Å). Attractive interaction N1 ···H21a 2.48 Å
(2.67 Å) is observed between the H1 atom and the
aromatic ring; this interaction cannot be regarded as
intramolecular hydrogen bond, for the C13H21aN1 angle
is 103°. Among structural features common for both
molecules, shortening of the N1–C4 bond to 1.263(2) Å
in VIa and 1.267(2) Å in VIIIa against average bond
length 1.279 Å should be noted.
(E)-VIII
The chlorination of aminophenols IIIa–IIIc in
acetic acid led to the formation of anomalous products,
4-aroylimino-6-tert-butyl-2,3,5,6-tetrachlorocyclohex-
2-en-1-ones VIIIa–VIIIc, i.e., the reaction involved
replacement of one tert-butyl group by chlorine atom.
The chemical shifts of 5-H (δ 5.34–5.37 ppm) and
C6 (δC 84.25 ppm) in the H and 13C NMR spectra
1
indicated axial orientation of the tert-butyl group in
molecules VIII [1]. Presumably, compounds VIII are
formed through intermediate 4-aroylimino-2,6-di-tert-
butyl-5,6-dichlorocyclohex-2-en-1-ones that are anal-
ogous to compounds V; the subsequent elimination of
isobutane molecule gives N-aroyl-2-tert-butyl-5,6-di-
chloro-1,4-benzoquinone imine which takes up the
second chlorine molecule at the double C=C bond sub-
stituted by tert-butyl group. Polo et al. [5] previously
reported on the replacement of the tert-butyl group in
2,6-di-tert-butyl-1,4-benzoquinone 4-oxime by
chlorine in the reaction with S2Cl2 in the presence of
The existence of compounds V–VIII as Z and E
isomers is related to their configurational stability and
is determined by steric effect of the substituents in
positions 3 and 5. For example, the hydrogen atom at
the sp2-hybridized C3 carbon atom and chlorine and
hydrogen atoms at the sp3-hybridized C5 atom in cy-
clohexene structure V exert equivalent steric effects on
the arylsulfonyl group, and compounds V in solution
exist as equimolar mixtures of Z and E isomers. Steric
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 6 2008

AVDEENKO et al.
810
C12
C14
C13
C11
Cl1
Cl2
C6
C5
C1
O1
N1
C4
O2
C9
C2
C7
Cl3
C3
C15
C21
C8
C16
C10
C20
C17
C19
C18
Fig. 1. Structure of the molecule of N-(3,5-di-tert-butyl-5,6,6-trichloro-4-oxocyclohex-2-en-1-ylidene)benzamide (VIa) according to
the X-ray diffraction data.
C8
C10
C7
O2
C9
Cl4
C17
C11
C6
C5
N1
C1
C16
C12
C4
O1
C3
Cl3
C2
C13
Cl1
C15
Cl2
C14
Fig. 2. Structure of the molecule of N-(5-tert-butyl-2,3,5,6-tetrachloro-4-oxocyclohex-2-en-1-ylidene)benzamide (VIIIa) according
to the X-ray diffraction data.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 6 2008

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... VIII.
811
effect on the ArX group of two chlorine atoms at the
sp3-hybridized C5 atom in compounds VI and VII is
much stronger than that of the chlorine atom at the
sp2-hybridized C3 atom; therefore, these compounds in
solution exist only as Z isomers. By contrast, steric
effect on the ArCO group of the Cl and H atoms on C5
(sp3) in structure VIII is considerably weaker than the
effect of Cl on C3 (sp2), and compounds VIII exist
only as E isomers.
0.45 mm–1; F(000) = 1792. Total of 10977 reflections
were measured, 3677 of which were independent
(Rint = 0.025). Absorption by the crystal was taken into
account on a semiempirical level, Tmin. = 0.948, Tmax
=
0.956 [10]. The final divergence factors were wR2 =
0.107 (for 3677 reflections) and R1 = 0.040 [for 2623
reflections with F > 4σ(F), S = 0.932].
Compound VI I Ia . Monoclinic crystals,
C17H15Cl4NO2, with the following unit cell parameters
(100 K): a = 7.9010 (2), b = 20.2480 (4), c =
11.1500 (2) Å; β = 96.399 (2)°, V = 1772.66 (2) Å3;
M 407.10; Z = 4; space group P21/n; dcalc = 1.525 g×
cm–3; μ(MoKα) = 0.677 mm–1; F(000) = 832. Total of
12382 reflections were measured, 3064 of which were
independent (Rint = 0.028). Absorption by the crystal
was taken into account on a semiempirical level,
Quinone oxime esters, 4-aroyloxyimino- and 4-aryl-
sulfonyloxymino-2,6-di-tert-butylcyclohexa-2,5-dien-
1-ones IXa–IXc and Xa–Xc [Ar = Ph (a), 4-MeC6H4
(b), 4-O2NC6H4 (c)] failed to undergo halogenation.
Thus chlorination of N-aroyl(arylsulfonyl)-2,6-di-
tert-butyl-1,4-benzoquinone imines gives cyclohex-
enone derivatives in which the tert-butyl group at the
sp3-hybridized carbon atom occupies exclusively the
axial position, indicating that the process involves
formation of intermediate carbocation and subsequent
syn-addition of the second chlorine atom [8]. The Z/E
isomer ratio of the addition products is determined by
their configurational stability.
T
min = 0.850, Tmax = 0.940. The final divergence factors
were wR2 = 0.063 (for 3024 reflections) and R1 = 0.028
[for 2938 reflections with F > 4σ(F), S = 1.054].
The complete sets of crystallographic data for com-
pounds VIa and VIIIa, including the final coordinates
of atoms and geometric parameters of molecules, were
deposited to the Cambridge Crystallographic Data
Center, entry nos. CCDC 632049 and CCDC 632048,
respectively.
EXPERIMENTAL
1
The H and 13C NMR spectra were recorded from
Initial compounds Ib, Ic, and IIIa–IIIc were re-
ported in [2], and IIa, IIc, IVa, and IVc, in [3, 11].
solutions in CDCl3 on a Varian VXR-300 spectrometer
operating at 300 MHz; the chemical shifts were meas-
ured relative to tetramethylsilane. Thin-layer chroma-
tography was performed on Silufol UV-254 plates;
samples were applied as solutions in chloroform, and
the chromatograms were eluted with benzene–hexane
(10:1); spots were visualized under UV light.
Quinone oxime ethers IXa–IXc and Xa–Xc were
synthesized by acylation of 2,6-di-tert-butyl-4-nitroso-
phenol with the corresponding substituted benzoyl
chlorides or arenesulfonyl chlorides in diethyl ether in
the presence of triethylamine according to the proce-
dure described in [12].
The X-ray diffraction data for single crystals of
compound VIa and VIIIa were acquired at 20°C using
an Xcalibur-3 diffractometer (MoKα irradiation, CCD
Chlorination of quinone imines Ia, Ib, IIa, and
IIc and aminophenols IIIa–IIIc, IVa, and IVc.
A stream of dry chlorine was passed at a flow rate of
15–20 ml/min at 35–75°C through a solution of
2 mmol of quinone imine Ia, Ib, IIa, or IIc or amino-
phenol IIIa–IIIc, IVa, or IVc in 3 ml of chloroform,
acetic acid, or 1:5 DMF–AcOH mixture. The sub-
strate-to chlorine ratio was controlled by the gain in
weight and was varied from 1:1 to 1:4.5. After 24 h,
the precipitate was filtered off and recrystallized from
acetic acid.
detector, graphite monochromator, ω-scanning, 2θmax
=
50°). The structures were solved by the direct method
and were refined with respect to F2 by full-matrix
least-squares procedure in anisotropic approximation
for non-hydrogen atoms using SHELXTL software
package [9]. The positions of hydrogen atoms were
determined by difference syntheses of electron density
and were refined using the riding model with unfixed
Uiso (VIa) or in isotropic approximation (VIIIa).
Insofar as compound Va was isolated in a mixture
with VIIa, its melting point and elemental composition
were not determined.
Compound VIa. Monoclinic crystals, C21H24Cl3NO2,
with the following unit cell parameters (293 K): a =
26.151(4), b = 8.214(2), c = 20.897(3) Å; β =
108.294(13)°; V = 4261.8(1) Å3; M 428.76; Z = 8;
space group C2/c; dcalc = 1.336 g/cm3; μ(MoKα) =
N-(3,5-Di-tert-butyl-5,6-dichloro-4-oxocyclohex-
2-en-1-ylidene)benzenesulfonamide (Va). 1H NMR
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 6 2008

AVDEENKO et al.
812
4
spectrum, δ, ppm: Z isomer: 7.98 d (1H, 2-H, J =
8.19–8.39 d.d (4H, Harom, J = 8.7 Hz). Found, %:
Cl 22.07, 22.35. C21H23Cl3N2O4. Calculated, %:
Cl 22.45.
4
2.1 Hz), 4.97 d (1H, 6-H, J = 2.1 Hz), 1.18 d and
1.31 d (9H each, t-Bu), 7.58–8.07 m (5H, Ph);
E isomer: 6.80 d (1H, 2-H, J = 2.1 Hz), 6.32 d (1H,
6-H, J = 2.1 Hz), 1.18 d and 1.31 d (9H each, t-Bu),
4
N-(3,5-Di-tert-butyl-5,6,6-trichloro-4-oxocyclo-
hex-2-en-1-ylidene)benzenesulfonamide (VIIa) was
synthesized from compound IVa. Yield 58%, mp 150–
4
7.58–8.07 m (5H, Ph).
1
N-(3,5-Di-tert-butyl-5,6-dichloro-4-oxocyclohex-
2-en-1-ylidene)-4-nitrobenzenesulfonamide (Vc)
(a mixture of Z and E isomers at a ratio of 55:45).
152°C. H NMR spectrum, δ, ppm: 8.17 s (1H, 2-H),
1.36 s and 1.19 s (9H each, t-Bu), 7.58–8.07 m (5H,
13
Ph). C NMR spectrum, δC, ppm: 187.16 (C4), 167.25
1
(C3), 158.33 (C1), 139.77 (C1′), 133.68 (C4′), 129.15
(C3′, C5′), 128.11 (C2), 127.36 (C2′, C6′), 94.63 (C6),
93.21 (C5), 42.82 and 37.47 (Me3C), 29.48 and 29.07
(Me3C). Found, %: Cl 22.81, 22.99. C20H24Cl3NO3S.
Calculated, %: Cl 22.88.
Yield 63%, mp 168–170°C. H NMR spectrum, δ,
ppm, Z isomer: 7.90 d (1H, 2-H, 4J = 2.1 Hz), 4.95 d
4
(1H, 6-H, J = 2.1 Hz), 1.19 d and 1.33 d (9H each,
t-Bu), 8.18–8.47 d.d (4H, Harom, J = 9.0 Hz); E isomer:
4
4
6.79 d (1H, 2-H, J = 2.1 Hz), 6.19 d (1H, 6-H, J =
2.1 Hz), 1.19 d and 1.33 d (9H each, t-Bu), 8.18–
N-(5-tert-Butyl-2,3,5,6-tetrachloro-4-oxocyclo-
hex-2-en-1-ylidene)benzamide (VIIIa). Yield 60%,
13
8.47 d.d (4H, Harom, J = 9.0 Hz). C NMR spectrum,
δC, ppm: 189.09, 188.94 (C4); 171.98, 171.95 (C1);
162.72, 159.75 (C3); 150.61 (C4′); 145.07, 144.81 (C1′);
135.65, 127.91 (C2); 128.96, 128.77 (C2′, C6′); 124.41,
124.34 (C3′, C5′); 86.90, 86.48 (C5); 67.16, 58.97 (C6);
41.71, 41.48, 37.35, 37.01 (CMe3); 29.00, 28.22, 28.10
(Me3C). Found, %: Cl 14.67, 15.01. C20H24Cl2N2O5.
Calculated, %: Cl 14.92.
1
mp 104–106°C. H NMR spectrum, δ, ppm: 5.35 s
(1H, 6-H), 1.21 s (9H, t-Bu), 7.50–7.98 m (5H, Ph).
13C NMR spectrum, δC, ppm: 181.63 (C4), 177.85
(C=O, amide), 155.64 (C1), 144.08 and 141.50 (C2,
C3), 134.65 (C4′), 130.89 (C1′), 129.65 (C2′, C6′), 128.93
(C3′, C5′), 84.25 (C5), 59.00 (C6), 42.43 (Me3C), 27.45
(Me3C). Found, %: Cl 34.56, 34.78. C17H15Cl4NO2.
Calculated, %: Cl 34.83.
N-(3,5-Di-tert-butyl-5,6,6-trichloro-4-oxocyclo-
hex-2-en-1-ylidene)benzamide (VIa). Yield 57%,
mp 108–110°C. H NMR spectrum, δ, ppm: 6.84 s
N-(5-tert-Butyl-2,3,5,6-tetrachloro-4-oxocyclo-
1
hex-2-en-1-ylidene)-4-methylbenzamide (VIIIb).
(1H, 2-H), 1.26 s and 1.23 s (9H each, t-Bu), 7.51–
8.02 m (5H, Ph). 13C NMR spectrum, δC, ppm: 187.52
(C4), 178.02 (C=O, amide), 159.25 (C1), 156.09 (C3),
134.21 (C4′), 131.95 (C1′), 129.51 (C2′, C6′), 128.95
(C3′, C5′), 128.46 (C2), 94.34 (C5), 92.85 (C6), 42.97
and 36.81 (Me3C), 29.52 and 28.99 (Me3C). Found, %:
Cl 24.52, 24.77. C21H24Cl3NO2. Calculated, %:
Cl 24.80.
1
Yield 42%, mp 158–160°C. H NMR spectrum, δ,
ppm: 5.34 s (1H, 6-H), 1.21 s (9H, t-Bu), 7.30–
7.86 d.d (4H, Harom, J = 8.1 Hz), 2.45 s (3H, MeC6H4).
Found, %: Cl 33.57, 33.81. C18H17Cl4NO2. Calculated,
%: Cl 33.67.
N-(5-tert-Butyl-2,3,5,6-tetrachloro-4-oxocyclo-
hex-2-en-1-ylidene)-4-nitrobenzamide (VIIIc). Yield
1
59%, mp 162–164°C. H NMR spectrum, δ, ppm:
N-(3,5-Di-tert-butyl-5,6,6-trichloro-4-oxocyclo-
hex-2-en-1-ylidene)-4-methylbenzamide (VIb). Yield
56%, mp 110–112°C. H NMR spectrum, δ, ppm:
5.37 s (1H, 6-H), 1.23 s (9H, t-Bu), 8.14–8.39 d.d
(4H, Harom, J = 9.0 Hz). Found, %: Cl 31.15, 31.42.
C17H14Cl4N2O4. Calculated, %: Cl 31.37.
1
6.83 s (1H, 2-H), 1.26 s and 1.22 s (9H each, t-Bu),
7.31–7.91 d.d (4H, Harom, J = 8.1 Hz), 2.45 s (3H,
MeC6H4). 13C NMR spectrum, δC, ppm: 187.67 (C4),
178.03 (C=O, amide), 159.02 (C1), 155.95 (C3), 145.32
(C4′), 129.68 (C2′, C6′), 129.62 (C3′, C5′), 129.52 (C1′),
128.58 (C2), 94.40 (C6), 93.04 (C5), 43.01 and 38.81
(Me3C), 29.56 and 29.02 (Me3C), 21.86 (MeC6H4).
Found, %: Cl 23.68, 23.90. C22H26Cl3NO2. Calculated,
%: Cl 24.02.
Bromination of quinone imines Ib, Ic, IIa, and
IIc and aminophenols IIIc and IVc (general proce-
dure). Compound Ib, Ic, IIa, IIc, IIIc, or IVc,
2 mmol, was dissolved in 3 ml of DMF–AcOH (1:5),
a solution of bromine in the same solvent mixture was
added dropwise under stirring to a substrate-to-
bromine ratio of 1:5, and the mixture was heated at
70–80°C.
N-(3,5-Di-tert-butyl-5,6,6-trichloro-4-oxocyclo-
hex-2-en-1-ylidene)-4-nitrobenzamide (VIc). Yield
67%, mp 180–182°C. H NMR spectrum, δ, ppm:
Chlorination of p-quinone oxime esters IXa–IXc
and Xa–Xc (general procedure). A stream of dry
chlorine was passed at a flow rate of 15–20 ml/min at
65–75°C through a solution of 2 mmol of quinone
1
6.84 s (1H, 2-H), 1.26 s and 1.25 s (9H each, t-Bu),
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 6 2008

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... VIII.
813
3. Belov, V.V., Loban’, S.V., Burmistrov, K.S., and Prosya-
oxime ether IXa–IXc or Xa–Xc in 3 ml of AcOH,
DMF–AcOH (1 :5), or MeOH until a substrate-to-
chlorine ratio of 1:7 was attained. After 24 h, the pre-
cipitate was filtered off and recrystallized from acetic
acid. We thus isolated unreacted initial compounds.
nik, A.V., Zh. Org. Khim., 1983, vol. 19, p. 825.
4. Avdeenko, A.P. and Konovalova, S.A., Russ. J. Org.
Chem., 2006, vol. 42, p. 349.
5. Polo, C., Ramos, V., and Torroba, T., Tetrahedron, 1998,
vol. 54, p. 223.
Bromination of p-quinone oxime esters IXc and
Xc (general procedure). Compound IXc or Xc,
2 mmol, was dissolved in 3 ml of DMF, DMF–AcOH
(1:5), or MeOH, and a solution of bromine in the same
solvent was added dropwise under stirring to a sub-
strate-to-bromine ratio of 1:5. The mixture was heated
to 70°C and kept for several minutes at that tempera-
ture. After cooling, the precipitate was filtered off,
washed with acetic acid, and recrystallized from acetic
acid. Unchanged initial compounds were thus isolated.
6. Zefirov, Yu.V. and Zorkii, P.M., Usp. Khim., 1989,
vol. 58, p. 713.
7. Burgi, H.-B. and Dunitz, J.D., Structure Correlation,
Weinheim: VCH, 1994, vol. 2, p. 741.
8. Avdeenko, A.P., Konovalova, S.A., Il’chenko, A.Ya.,
and Glinyanaya, N.M., Russ. J. Org. Chem., 2006,
vol. 42, p. 64.
9. Sheldrick, G.M., SHELXTL PLUS. PC Version. A Sys-
tem of Computer Programs for the Determination of
Crystal Structure from X-ray Diffraction Data. Rev. 5.1,
1998.
REFERENCES
10. Blessing, R.H., Acta Crystallogr., Sect. A, 1995, vol. 51,
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1. Avdeenko, A.P., Pirozhenko, V.V., Shishkin, O.V.,
Shishkina, S.V., Konovalova, S.A., and Ludchenko, O.N.,
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11. Burmistrov, K.S., Doctoral (Chem.) Dissertation,
Dnepropetrovsk, 1990.
2. Pirozhenko, V.V. and Avdeenko, A.P., Russ. J. Org.
Chem., 1995, vol. 31, p. 1514.
12. Titov, E.A. and Burmistrov, S.I., Ukr. Khim. Zh., 1960,
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