Halogenation of N-substituted p-quinone monoimines and p-quinone monooxime esters: X. Halogenation of N-aroyl-2,5(2,3)-dialkyl-1,4-benzoquinone monoimines and their reduction products

Article abstract of DOI:10.1134/S1070428009120094

Introduction of a strong electron-withdrawing substituent to the nitrogen atom of 2,5(2,3)-dialkyl-1,4-benzoquinone imines makes their halogenation products, the corresponding cyclohexene derivatives, very unstable and favors halogenation of methyl groups

Full text of DOI:10.1134/S1070428009120094

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2009, Vol. 45, No. 12, pp. 1799–1813. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © A.P. Avdeenko, S.A. Konovalova, O.N. Ludchenko, 2009, published in Zhurnal Organicheskoi Khimii, 2009, Vol. 45, No. 12,
pp. 1804–1817.
Halogenation of N-Substituted p-Quinone Monoimines
and p-Quinone Monooxime Esters: X.* Halogenation
of N-Aroyl-2,5(2,3)-dialkyl-1,4-benzoquinone Monoimines
and Their Reduction Products
A. P. Avdeenko, S. A. Konovalova, and O. N. Ludchenko
Donbass State Machine-Building Academy, ul. Shkadinova 72, Kramatorsk, 84313 Ukraine
e-mail: chimist@dgma.donetsk.ua
Received August 1, 2008
Abstract—Introduction of a strong electron-withdrawing substituent to the nitrogen atom of 2,5(2,3)-dialkyl-
1,4-benzoquinone imines makes their halogenation products, the corresponding cyclohexene derivatives, very
unstable and favors halogenation of methyl groups in the quinoid ring. Bromination of 4-amino-N-aroyl-2,5-
dialkyl-6-bromophenols gave 2,5-dialkyl-6-benzoyloxy-3,5-dibromocyclohex-2-ene-1,4-diones.
DOI: 10.1134/S1070428009120094
We previously examined halogenation of N-aryl-
sulfonyl-2,5-dialkyl-1,4-benzoquinone imines [2] and
found that the main factors determining the direction
of addition of halogen molecule are the size of substit-
uents in the quinoid ring and the size of the halogen
atom. The presence of a strong electron-withdrawing
substituent on the nitrogen atom, in particular aroyl
group, also considerably affects the halogenation proc-
ess [1, 3, 4]. Halogenation of N-aroyl-2,5(2,3)-dialkyl-
substituted 1,4-benzoquinone imines and their reduc-
tion products, N-aroyl-2,5(2,3)-dialkyl-4-aminophe-
nols was not reported previously.
Due to the presence of a methyl or isopropyl group
in the ortho position with respect to the imino nitrogen
atom, quinone imines I–III in solution exist as a single
1
isomer, which is confirmed by the H NMR data. In
1
the H NMR spectra of N-aroyl-2,5-dialkyl-1,4-benzo-
quinone imines, differences in the chemical shifts of
protons in the quinoid ring were considerably smaller
than those observed for analogous N-arylsulfonyl de-
rivatives; therefore, assignment of signals in the spec-
tra of compounds I–III was more difficult. The 3-H
proton in I–III resonated in the 1H NMR spectra in the
region δ 6.58–6.66 ppm, while the 6-H signal was
located at δ 6.44–6.59 ppm; the corresponding signals
of N-arylsulfonyl derivatives appeared in the regions
δ 7.89–7.96 and 6.50–6.64 ppm, respectively [2].
The goal of the present work was to study halo-
genation of N-aroyl-2,5(2,3)-dialkyl-1,4-benzoquinone
imines, elucidate specific features of the halogenation
process, and compare these reactions with halogena-
tion of the corresponding N-arylsulfonyl derivatives.
As substrates we used N-aroyl-1,4-benzoquinone
imines which, like N-arylsulfonyl derivatives studied
previously [2], contained different alkyl substituents
(i-Pr, Me) in positions 2 and 5 of the quinoid ring:
N-aroyl-2,5-dimethyl-, -2-isopropyl-5-methyl-, and
-5-isopropyl-2-methyl-1,4-benzoquinone imines Ia–Ic,
IIa–IIc, and IIIa–IIIc, and their reduction products,
4-amino-N-aroyl-2,5-dimethyl-, 2-isopropyl-5-methyl-,
and -5-isopropyl-2-methylphenols IVa–IVc, Va–Vc,
and VIa–VIc.
N-Aroyl-2,5-dialkyl-1,4-benzoquinone imines I–III
were synthesized by oxidation of the corresponding
aminophenols IV–VI with lead tetraacetate in acetic
acid. The chlorination of quinone imines I–III and
aminophenols IV–VI was performed using gaseous
chlorine, and the bromination was carried out with
molecular bromine in CHCl3, AcOH, DMF, or DMF–
AcOH (1:5) at different substrate-to-reagent ratios
under different temperature conditions. The results are
given in Scheme 1. Unlike N-arylsulfonyl-2,5-dialkyl-
1,4-benzoquinone imines which took up one halogen
molecule [2], the halogenation of N-aroyl-2,5-dialkyl-
1,4-benzoquinone imines gave only several analogous
cyclohexene compounds, namely N-(5,6-dichloro-2,5-
* For communication IX, see [1].
1799

AVDEENKO et al.
1800
Scheme 1.
O
O
N
Me
Me
Br
Cl
Cl
Me
Br
Pr-i
N
COPh
COAr
VII
VIIIb, VIIIc
O
Br
Br
Pr-i
XIXa–XIXc
Br2
Me
N
COC6H4NO2-4
O
Br
Br
Br
Me
COAr
IX
i-Pr
O
N
OH
R1
Hlg
R2
R1
R2
Hlg2
N
R2
XXIIa–XXIIc
HN
COAr
COAr
Ia–Ic, IIa–IIc
IIIa–IIIc
Xa–Xc, XIa–XIc, XIIa–XIIc
XIIIa–XIIIc, XIVa–XIVc, XVa–XVc
O
OH
Hlg
R2
R1
R1
Hlg2
R2
N
HN
COAr
COAr
XVIa–XVIc, XVIIa–XVIIc, XVIIIa–XVIIIc
XIXa–XIXc, XXa–XXc, XXIa–XXIc
IVa–IVc, Va–Vc
VIa–VIc
Hlg2
O
R1
Hlg
Hlg
R2
Hlg
COAr
N
XXIIIa–XXIIIc, XXIVa, XXIVc, XXVa–XXVc
XXVIa–XXVIc, XXVIIa, XXVIIc
OH
O
N
R1
Hlg
R1
Hlg
R2
Hlg2
Hlg
R2
Hlg
HN
COAr
COAr
Xa–Xc, XIa, XIc, XIIa–XIIc
XIIIa–XIIIc, XIVa–XIVc, XVa, XVc
XXIIIa–XXIIIc, XXIVa, XXIVc, XXVa–XXVc
XXVIa–XXVIc, XXVIIa, XXVIIc
Ar =Ph (a), 4-MeC6H4 (b), 4-O2NC6H4 (c); I, IV, X, XI, XVI, XVII, XXIII, XXIV, R1 = R2 = Me; II, V, XII, XIII, XVIII, XIX,
XXV, R1 = i-Pr, R2 = Me; III, VI, XIV, XV, XX, XXI, XXVI, XXVII, R1 = Me, R2 = i-Pr; X, XII, XIV, XVI, XVIII, XX,
XXIII, XXV, XXVI, Hlg = Cl; XI, XIII, XV, XVII, XIX, XXI, XXIV, XXVII, Hlg = Br.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 12 2009

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... X.
1801
dimethyl-4-oxocyclohex-2-en-1-ylidene)benzamide
(VII), N-(5,6-dibromo-2-isopropyl-5-methyl-4-oxocy-
clohex-2-en-1-ylidene)benzamides VIIIb and VIIIc,
and N-(5,6-dibromo-3-isopropyl-6-methyl-4-oxocyclo-
hex-2-en-1-ylidene)-4-nitrobenzamide (IX). Obvious-
ly, the corresponding 4-aroyliminocylohex-2-en-1-one
derivatives are unstable due to effect of a strong elec-
tron-withdrawing substituent on the nitrogen atom
(aroyl group), and they readily undergo dehydrohalo-
genation.
characteristically displayed in the 13C NMR spectra
two upfield signals from sp3-hybridized carbon atoms
at δC 64.99, 58.88 (CClCH3, CHCl) and 57.52,
49.37 ppm (CBrCH3, CHBr), respectively.
By chlorination of quinone imines I–III and amino-
phenols IV–VI we obtained N-(3-chloro-4-hydroxy-
2,5-dimethylphenyl)benzamides Xa–Xc, N-(3-chloro-
4-hydroxy-5-isopropyl-2-methylphenyl)benzamides
XIIa–XIIc, N-(3-chloro-4-hydroxy-2-isopropyl-5-
methylphenyl)benzamides XIVa–XIVc, N-(3-chloro-
2,5-dimethyl-4-oxocyclohexa-2,5-dien-1-ylidene)benz-
amides XVIa–XVIc, N-(3-chloro-5-isopropyl-2-meth-
yl-4-oxocyclohexa-2,5-dien-1-ylidene)benzamides
XVIIIa–XVIIIc, N-(3-chloro-2-isopropyl-5-methyl-4-
oxocyclohexa-2,5-dien-1-ylidene)benzamides XXa–
XXc, N-(3,5,6-trichloro-2,5-dimethyl-4-oxocyclohex-
2-en-1-ylidene)benzamides XXIIIa–XXIIIc, N-(3,5,6-
trichloro-5-isopropyl-2-methyl-4-oxocyclohex-2-en-1-
ylidene)benzamides XXVa–XXVc, and N-(3,5,6-tri-
chloro-2-isopropyl-5-methyl-4-oxocyclohex-2-en-1-
ylidene)benzamides XXVIa–XXVIc.
Compounds VII, VIIIb, and VIIIc are products of
addition of halogen molecule at the double C=C bond
located syn with respect to the substituent on the nitro-
gen atom in quinone imines Ia, IIIb, and IIIc, respec-
tively. Chlorine addition in the chlorination of quinone
imine Ia strictly follows general relations found previ-
ously for the halogenation of N-arylsulfonyl-2,5-di-
methyl-1,4-benzoquinone imines [2]. The bromination
of compounds IIIb and VIIIc could occur at both
double C=C bonds in the quinoid ring, but only isomer
VIII was isolated. In the reaction with quinone imine
IIc, as might be expected, bromine molecule adds at
the more sterically accessible double C=C bond in the
trans position with respect to the substituent on the
nitrogen atom.
Compounds XXIII, XXV, and XXVI are the final
stable chlorination products of the corresponding qui-
none imines I–III. The formation of aminophenols X,
XII, and XIV in more than 50% yield from amino-
phenols IV–VI at a substrate-to-chlorine ratio of 1:1
indicates that the reaction occurs as electrophilic sub-
stitution of hydrogen in the benzene ring of amino-
phenol IV–VI by chlorine atom. Obviously, aminophe-
nols X, XII, and XIV are then oxidized with chlorine
to the corresponding quinone imines which take up one
more chlorine molecule at the double C=C bond to
give stable trichlorocyclohexene derivatives XXIII,
XXV, and XXVI.
The structure of compounds VII, VIIIb, VIIIc, and
1
IX was confirmed by the H and 13C NMR spectra.
1
The 3-H signal appears in the H NMR spectrum of
N-(5,6-dichloro-2,5-dimethyl-4-oxocyclohex-2-en-1-
ylidene)benzamide (VII) as a quartet at δ 6.52 ppm,
which is consistent with meta position of that proton
with respect to the C=N bond; the multiplicity of the
3-H signal results from coupling with protons in the
neighboring methyl group (δ 2.30 ppm, d). The
1H NMR spectrum of VII also contained a singlet from
6-H at δ 4.83 ppm, which is typical of a proton
attached to an sp3-hybridized carbon atom. The 3-H
proton in N-(5,6-dibromo-2-isopropyl-5-methyl-4-oxo-
cyclohex-2-en-1-ylidene)-4-methylbenzamide (VIIIb)
gave s singlet at δ 6.40 ppm, and the 6-H signal was
a singlet at δ 5.07 ppm. Compound IX in solution
exists as Z isomer, and the substituent on the nitrogen
atom is oriented syn with respect to the double C=C
bond in the quinoid ring. The 6-H proton in IX reso-
nates as a broadened singlet at δ 6.42 ppm; its position
is typical of protons at the quinoid C=C double bond.
The 3-H signal of IX was a singlet at δ 4.92 ppm; its
position corresponds to a proton at an sp3-hybridized
carbon atom neighboring to a carbonyl group. Protons
in the methyl group resonated in the spectrum as
a singlet at δ 2.31 ppm. Compounds VII and VIIIb
The bromination of quinone imines I–III afforded
N-(3-bromo-4-hydroxy-2,5-dimethylphenyl)benz-
amides XIa–XIc, N-(3-bromo-4-hydroxy-5-isopropyl-
2-methylphenyl)benzamides XIIIa–XIIIc, and
N-(3-bromo-4-hydroxy-2-isopropyl-5-methylphenyl)-
benzamides XVa–XVc. These compounds can be
formed only as a result of reduction of quinone imines
XVII, XIX, and XXI, respectively, with hydrogen bro-
mide liberated in the dehydrohalogenation of interme-
diate cyclohexene derivatives A which cannot be iso-
lated in most cases due to their instability (Scheme 2).
Analogous cyclohexene compound IX was obtained
only by bromination of quinone imine IIc.
The reduction of quinone imines XVII, XIX, and
XXI is possible due to higher redox potential of
N-aroyl-1,4-benzoquinone imines as compared to their
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 12 2009

AVDEENKO et al.
1802
Scheme 2.
O
Br
Br
R1
HBr
Br2
Br2
Ia–Ic, IIa–IIc
IIIa–IIIc
XVIIa–XVIIc, XIXa–XIXc
XXIa–XXIc
XIa–XIc, XIIIa–XIIIc
XVa–XVc
–HBr
R2
N
COAr
A
N-arylsulfonyl analogs [5]; no reduction of the latter
was observed previously [2]. By contrast, the bromina-
tion of N,N′-bis(arylsulfonyl)-1,4-benzoquinone di-
imines was accompanied by reduction process [6], for
their redox potentials are considerably higher than
those of the corresponding quinone monoimines [7].
while cyclohexene derivatives XXIV and XXVII were
isolated in the bromination of quinone imines I–III,
XVII, XIX, and XXI.
1
In the H NMR spectra of cyclohexene compounds
XXIIIa–XXIIIc, XXIVa, XXIVc, XXVa–XXVc,
XXVIa–XXVIc, XXVIIa, and XXVIIc, the singlet in
the region δ 4.78–5.10 ppm was assigned to 6-H
attached to the sp3-hybridized carbon atom in the ortho
position with respect to the imino carbon atom. Methyl
protons resonated as a singlet in the region δ 1.83–
2.06 ppm. The 13C NMR spectra of compounds
XXIIIa, XXIIIb, XXVIa, and XXVIb contained two
upfield signals belonging to sp3-carbon atoms at
δC 64.68–64.39 (CClCH3) and 59.19–58.05 ppm
(CHCl). The corresponding signals of compound
XXIVa are located in a stronger field relative to those
of XXIII and XXVI: δC 56.40 (CBrCH3) and
47.70 ppm (CHBr). The sp3-carbon atoms in the cyclo-
hexene ring of XXVa resonated at δC 82.86 (CClPr-i)
and 59.96 ppm (CHCl).
The bromination of aminophenol Vb in DMF with
molecular bromine at a reactant ratio of 1:6.5 at 35°C
gave 4-methyl-N-(5,5,6-tribromo-3-isopropyl-6-meth-
yl-4-oxocyclohex-2-en-1-ylidene)benzamide (XXIIb).
Compound XXIIb may be formed as a result of either
electrophilic replacement of hydrogen in the ortho-
position with respect to the hydroxy group in initial
aminophenol Vb, followed by oxidation and addition
of bromine molecule, or oxidation of aminophenol Vb,
addition of bromine molecule at the sterically less
hindered double C=C bond, dehydrobromination, and
addition of the second bromine molecule at the same
bond. Compound XXIIb was also synthesized by
1
bromination of quinone imine XIXb. In the H NMR
spectrum of XXIIb, the 2-H signal appeared as a sin-
glet at δ 6.58 ppm, and protons in the 6-methyl group
resonated as a singlet at δ 2.08 ppm, in keeping with
the assumed structure. The 13C NMR spectrum of
XXIIb contained signals from two sp3-carbon atoms at
δC 88.50 (CBr2) and 70.47 ppm (fragment CBrCH3).
In order to identify aminophenols X–XV, these
compounds were synthesized independently by hydro-
halogenation of quinone imines I–III and were then
oxidized to the corresponding quinone imines XVI–
XXI with lead tetraacetate in acetic acid. Attempts to
effect further hydrohalogenation of quinone imines
XVI–XXI were unsuccessful, and the initial com-
pounds were recovered from the reaction mixtures
(Scheme 3).
By bromination of aminophenols IV–VI we ob-
tained o-bromoaminophenols XIa–XIc, XIIIa–XIIIc,
and XVa–XVc, N-(3-bromo-2,5-dimethyl-4-oxocyclo-
hexa-2,5-dien-1-ylidene)benzamides XVIIa–XVIIc,
and N-(3,5,6-tribromo-2,5-dimethyl-4-oxocyclohex-2-
en-1-ylidene)benzamides XXIVa and XXIVc. In these
reactions, aminophenols XI, XIII, and XV are most
likely to be formed via electrophilic replacement of
hydrogen in initial aminophenols IV–VI by bromine.
Taking into account high redox potential of N-aroyl
derivatives, subsequent oxidation of aminophenols XI,
XIII, and XV with bromine and addition of another
bromine molecule seem to be improbable. Therefore,
quinone imines XVII, XIX, and XXI were isolated
mainly in the bromination of quinone imines I–III,
Scheme 3.
HHlg
HHlg
Pb(OAc)4
I–III
X–XV
XVI–XXI
The structure of quinone imines XVI–XXI was
1
proved by the H NMR data. The 6-H proton in XVI,
1
XVII, XX, and XXI resonated in the H NMR spectra
as a quartet in the region δ 6.62–6.71 ppm, i.e., in the
range corresponding to ortho position of that proton
with respect to the quinone imine C=N fragment. The
signal is split due to coupling with protons in the
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 12 2009

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... X.
1803
Scheme 4.
OH
O
OH
O
O
Br
Br
R1
O
Br
Me
Me
Br
R1
Br
Br2
Br2
Br
O
Br
Me
Br
R2
R2
BrCH2
Ph
HN
N
HN
COPh
COPh
COPh
XIa
XXVIII
XIa, XIIIa
XXIX, XXX
XXIX, R1 = R2 = Me; XXX, R1 = i-Pr, R2 = Me.
methyl group on C5; the 5-CH3 signal appeared as
a doublet at δ 1.98–2.02 ppm. The 6-H signal of
quinone imines XVIIIa–XVIIIc and XIXa–XIXc was
a doublet located in the region δ 6.59–6.61 ppm, while
the 2-CH3 group gave a singlet at δ 2.43–2.48 ppm.
X-ray analysis [1]. The IR spectrum of XXIX con-
tained carbonyl absorption bands at 1710, 1735, and
1590 cm–1; the latter was assigned to the ester car-
bonyl. In the 13C NMR spectrum of XXIX, carbonyl
carbon atoms in the cyclohexene ring resonated at
δC 186.35 and 183.66 ppm, and two upfield signals
(δC 78.73 and 58.09 ppm) were assigned to the sp3-hy-
bridized carbon atoms. Compounds XXIX and XXX
displayed in the 1H NMR spectra singlets from the 1-H
proton at δ 6.07–6.17 ppm and from the methyl group
on C6 at δ 2.00–2.27 ppm.
The bromination of aminophenol XIa with 5 equiv
of bromine in acetic acid at 70°C resulted in the
formation of N-(2,5,5,6-tetrabromo-6-bromomethyl-3-
methylcyclohex-2-en-1-ylidene)benzamide (XXVIII)
1
(Scheme 4) whose structure was confirmed by H and
13C NMR and IR spectra and elemental analysis. In the
1H NMR spectrum of XXVIII the CH2Br signal is
located at δ 4.36–4.43 ppm. Insofar as the CH2Br
group is attached to a chiral sp3-hybridized carbon
atom, protons therein are diastereotopic, and they ap-
pear in the spectrum as a doublet of doublets (J1 = 3.3,
J2 = 9.0 Hz). The 13C NMR spectrum of XXVIII con-
tained signals from two sp3-carbon atoms (C5, C6) at
δC 66.93 and 87.51 ppm and a signal from the CH2Br
group at δC 25.60 ppm. In the IR spectrum of this
compound we observed absorption band at 1720 cm–1
due to stretching vibrations of the carbonyl group.
We then examined halogenation of N-aroyl-2,3-di-
methyl-1,4-benzoquinone imines XXXIa and XXXIb
which exist in solution as a single isomer where both
methyl groups are located at the double C=C bond in
the anti position with respect to the N-aroyl group, thus
creating considerable steric hindrances to halogen ad-
dition at that double bond. Therefore, addition of the
first halogen molecule should be strictly regioselective
and should occur at the unsubstituted C=C bond in the
quinoid ring. Quinone imines XXXIa and XXXIb
were synthesized by oxidation of the corresponding
N-aroyl-4-amino-2,3-dimethylphenols XXXIIa and
XXXIIb with lead tetraacetate in acetic acid. Com-
pounds XXXIIa and XXXIIb were prepared in turn by
acylation of 4-amino-2,3-dimethylphenol with benzoyl
and 4-methylbenzoyl chlorides, respectively.
Bromination of the methyl group suggests the pres-
ence in the reaction mixture of radical species which
may be formed as a result of oxidation of liberated
hydrogen bromide with atmospheric oxygen. Halo-
genation of methyl group at the quinoid ring was
observed by us previously only in the bromination of
N-aroyl-2,6-dimethyl-1,4-benzoquinone imines and
chlorination of N-aroyl-3,5-dimethyl-1,4-benzoqui-
none imines [1].
The chlorination and bromination of benzoquinone
imines XXXIa and XXXIb and aminophenols
XXXIIa and XXXIIb were carried out according to
the procedures described above for the halogenation of
2,5-dialkyl-substituted derivatives. The results are
given in Scheme 5. As expected, we isolated no prod-
ucts of addition of one halogen molecule at the unsub-
stituted double bond of quinone imines XXXIa and
XXXIb because of their very low stability. Obviously,
the primary adducts underwent dehydrohalogenation
with formation of N-(5-halo-2,3-dimethyl-4-oxocyclo-
hexa-2,5-dien-1-ylidene)benzamides XXXVa,
XXXVb, XXXVIa, and XXXVIb. At a lower sub-
3,6-Dialkyl-4,6-dibromo-2,5-dioxocyclohex-2-en-
1-yl benzoates XXIX and XXX were synthesized by
bromination of aminophenols XIa and XIIIa, respec-
tively, with 2 equiv of molecular bromine in DMF at
60°C (Scheme 4). Compound XXX was formed only
in a mixture with cyclohexene derivative XXIIa. Anal-
ogous dioxocyclohexenes were obtained previously in
the bromination of N-aroyl-2,6-dimethyl-1,4-benzo-
quinone imines, and their structure was proved by
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 12 2009

AVDEENKO et al.
1804
Scheme 5.
O
Me
Me
N
COAr
XXXIa, XXXIb
Hlg2
or HHlg
OH
O
N
O
N
O
N
O
O
Me
Cl
Cl
Me
Br
Br
Br
Br
COAr
XXXVIIIa, XXXVIIIc
Me
Br
Br
Me
Me
Me
Hlg
Me
Me
Hlg
Cl
Me
Br
Me
Me
Cl
Cl
Me
Br
HN
N
O
COAr
COAr
COAr
COPh
XXXIIIa, XXXIIIb
XXXIVa, XXXIVb
XXXVa, XXXVb
XXXVIa, XXXVIb
XXXVIIa, XXXVIIb
XXXIX
XL
Pb(OAc)4, AcOH
Hlg2
OH
Me
Me
HN
COAr
XXXIIa, XXXIIb
Ar = Ph (a), 4-MeC6H4 (b), 3-Br-4-MeC6H3 (c); XXXIII, XXXV, Hlg = Cl; XXXIV, XXXVI, Hlg = Br.
strate-to-halogen ratio we also isolated N-(5-halo-4-
hydroxy-2,3-dimethylphenyl)benzamides XXXIIIa,
XXXIIIb, XXXIVa, and XXXIVb. Quinone imines
XXXV and XXXVI were also synthesized by oxida-
tion of aminophenols XXXIII and XXXIV with lead
tetraacetate (Scheme 5). Further chlorination of com-
pounds XXXVa and XXXVb resulted in chlorine ad-
dition only at the methyl-substituted double C=C bond
to give stable N-(3,5,6-trichloro-5,6-dimethyl-4-oxo-
cyclohex-2-en-1-ylidene)benzamides XXXVIIa and
XXXVIIb.
and XXXVIb. These intermediates were unstable, and
they readily lose hydrogen bromide with subsequent
addition of one more bromine molecule. In this case,
the second bromine molecule added at both dimethyl-
substituted double C=C bond, yielding N-(5,5,6,6-
tetrabromo-2,3-dimethylcyclohex-2-en-1-ylidene)-
benzamide (XXXVIIIa), and the other C=C bond
(CH=CBr) to give N-(2,3,5,6-tetrabromo-5,6-dimethyl-
cyclohex-2-en-1-ylidene)benzamide (XXXIX); com-
pound XXXVIIIa was formed as the major product.
The chlorination of quinone imines XXXIa and
XXXIb was often accompanied by hydrolysis, so that
5,6-dichloro-2,3-dimethylcyclohex-2-ene-1,4-dione
(XL) was formed in high yield in many cases. Depend-
ing on the conditions, halogenation of N-aroyl-4-
Likewise, we failed to isolate the corresponding
N-(5,5,6-tribromo-2,3-dimethyl-4-oxocyclohex-2-en-
1-ylidene)benzamides which should be formed as a re-
sult of bromine addition to quinone imines XXXVIa
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HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... X.
1805
amino-2,3-dimethylphenols XXXIIa and XXXIIb led
to the formation of N-(5-halo-4-hydroxy-2,3-dimethyl-
phenyl)benzamides XXXIIIa, XXXIIIb, XXXIVa,
and XXXIVb, N-(3,5,6-trichloro-5,6-dimethyl-4-oxo-
cyclohex-2-en-1-ylidene)benzamides XXXVIIa and
XXXVIIb, or mixtures of bromine addition products
XXXVIIIa and XXXIX at different C=C bonds of the
quinoid ring. Aminophenols XXXIIIa, XXXIIIb,
XXXIVa, and XXXIVb were also synthesized by
hydrohalogenation of quinone imines XXXIa and
XXXIb (Scheme 5).
XXVa–XXVc, XXVIa–XXVIc, XXVIIa, and
XXVIIc, as well as in bromomethyl-substituted com-
pound XXVIII, follows from their H NMR spectra
where protons in the isopropyl group give rise to two
doublets (the CH2Br protons in XXVIII appear as
a doublet of doublets). These compounds attract
interest from the viewpoint of studying spontaneous
enantiomer resolution, which was revealed by us pre-
viously [9].
1
EXPERIMENTAL
Surprisingly, the bromination of N-(5-bromo-2,3-di-
methyl-4-oxocyclohexa-2,5-dien-1-ylidene)-4-methyl-
benzamide (XXXVIb) with 8 equiv of bromine in
DMF–AcOH at 55°C was accompanied by electro-
philic replacement of hydrogen in the p-tolyl ring, and
the product was 3-bromo-4-methyl-N-(5,5,6,6-tetra-
bromo-2,3-dimethylcyclohex-2-en-1-ylidene)benz-
amide (XXXVIIIc) (Scheme 5). Analogous process,
i.e., chlorination of the 4-methoxyphenylsulfonyl resi-
due, was observed previously only in the chlorination
of N-(4-methoxyphenyl)sulfonyl-1,4-benzoquinone
imines [8].
1
The H and 13C NMR spectra were measured on
a Varian VXR-300 spectrometer at 300 and 75.4 MHz,
respectively, using CDCl3 as solvent and tetramethyl-
silane as internal reference. The reaction mixtures were
analyzed by thin-layer chromatography on Silufol UV-
254 plates using benzene–hexane (10:1) as eluent;
spots were visualized under UV light.
N-(2,5-Dialkyl-4-oxocyclohexa-2,5-dien-1-yli-
dene)benzamides Ia–Ic, IIa–IIc, IIIa–IIIc, XXXIa,
and XXXIb and N-(2,5-dialkyl-4-hydroxyphenyl)-
benzamides IVa–IVc, Va–Vc, VIa–VIc, XXXIIa,
and XXXIIb were synthesized according to the proce-
dures described in [10, 11], and were recrystallized
from acetic acid.
The 6-H proton in quinone imines XXXV and
1
XXXVI resonated in the H NMR spectra at δ 7.03–
7.32 ppm; also, signals from protons in the two methyl
groups were observed at δ 2.16–2.17 and 2.29–
2.30 ppm as doublets with a coupling constant J of
0.9–1.2 Hz. Cyclohexene derivatives XXXVIIa and
N-(2,5-Dimethyl-4-oxocyclohexa-2,5-dien-1-
ylidene)benzamide (Ia). Yield 92%, mp 97–99°C.
1H NMR spectrum, δ, ppm: 1.94 d (3H, 5-Me, J =
1.2 Hz), 2.28 d (3H, 2-Me, J = 1.2 Hz), 6.59 q (1H,
3-H, J = 1.2 Hz), 6.66 q (1H, 6-H, J = 1.2 Hz), 7.48–
7.92 m (5H, Ph). Found, %: N 5.58, 5.82. C15H13NO2.
Calculated, %: N 5.85.
1
XXXVIIb displayed in the H NMR spectra a singlet
at δ 7.01–7.03 ppm due to proton at the double C=C
bond, and the methyl groups gave rise to two singlets
at δ 2.04 and 2.13–2.14 ppm. The spectra of
XXXVIIIa and XXXVIIIc contained two singlets
from protons in the methyl groups at δ 1.88–1.89 and
2.20–2.21 ppm, indicating that these groups are at-
tached to sp2-carbon atoms. The corresponding signals
of compound XXXIX, in which the methyl groups are
attached to sp3-hybridized carbon atoms, are located in
a stronger field, at δ 1.73 and 1.34 ppm. 5,6-Di-
chloro-2,3-dimethylcyclohex-2-ene-1,4-dione (XL)
N-(2,5-Dimethyl-4-oxocyclohexa-2,5-dien-1-
ylidene)-4-methylbenzamide (Ib). Yield 89%,
mp 116–118°C. H NMR spectrum, δ, ppm: 1.93 d
(3H, 5-Me, J = 1.2 Hz), 2.24 s (3H, 4-MeC6H4), 2.27 d
(3H, 2-Me, J = 1.2 Hz), 6.58 q (1H, 3-H, J = 1.2 Hz),
6.64 q (1H, 6-H, J = 1.2 Hz), 7.28–7.80 d.d (4H, C6H4,
J = 8.4 Hz). Found, %: N 5.10, 5.51. C16H15NO2. Cal-
culated, %: N 5.53.
1
1
showed in the H NMR spectrum an upfield singlet
N-(2,5-Dimethyl-4-oxocyclohexa-2,5-dien-1-
ylidene)-4-nitrobenzamide (Ic). Yield 94%, mp 187–
(δ 4.68 ppm) from the equivalent 5-H and 6-H protons
and a singlet at δ 2.09 ppm from the equivalent methyl
groups.
1
188°C. H NMR spectrum, δ, ppm: 1.97 d (3H, 5-Me,
J = 1.5 Hz), 2.29 d (3H, 2-Me, J = 1.8 Hz), 6.62 q (1H,
3-H, J = 1.8 Hz), 6.66 q (1H, 6-H, J = 1.5 Hz), 8.08–
8.35 d.d (4H, C6H4, J = 9.0 Hz). Found, %: N 9.58,
9.90. C15H12N2O4. Calculated, %: N 9.85.
Molecules VII, VIIIb, VIIIc, IX, XXIIIa–XXIIIc,
XXIVa, XXIVc, XXVa–XXVc, XXVIa–XXVIc,
XXVIIa, XXVIIc, and XXVIII possess an asym-
metric carbon atom. The presence of a chiral center in
isopropyl-substituted derivatives VIIIb, VIIIc, IX,
N-(5-Isopropyl-2-methyl-4-oxocyclohexa-2,5-di-
en-1-ylidene)benzamide (IIa). Yield 88%, mp 110–
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AVDEENKO et al.
1806
1
111°C. H NMR spectrum, δ, ppm: 1.02 d (6H,
5-CHMe2, J = 6.9 Hz), 2.27 d (3H, 2-Me, J = 1.5 Hz),
2.91–3.05 m (1H, 5-CH), 6.56 d (1H, 6-H, J = 0.9 Hz),
6.58 q (1H, 3-H, J = 1.5 Hz), 7.48–7.92 m (5H, Ph).
Found, %: N 5.08, 5.29. C17H17NO2. Calculated, %:
N 5.24.
N-(4-Hydroxy-2,5-dimethylphenyl)-4-methyl-
benzamide (IVb). Yield 78%, mp 266–268°C. Found,
%: N 5.24, 5.37. C16H17NO2. Calculated, %: N 5.49.
N-(4-Hydroxy-2,5-dimethylphenyl)-4-nitrobenz-
amide (IVc). Yield 96%, mp 198–200°C. Found, %:
N 9.53, 9.85. C15H14N2O4. Calculated, %: N 9.78.
N-(5-Isopropyl-2-methyl-4-oxocyclohexa-2,5-di-
en-1-ylidene)-4-methylbenzamide (IIb). Yield 91%,
mp 110–111°C. 1H NMR spectrum, δ, ppm: 1.02 d (6H,
5-CHMe2, J = 6.9 Hz), 2.27 d (3H, 2-Me, J = 1.5 Hz),
2.44 s (3H, 4-MeC6H4), 2.91–3.05 m (1H, 5-CH),
6.56 d (1H, 6-H, J = 0.9 Hz), 6.58 q (1H, 3-H, J =
1.5 Hz), 7.28–7.81 d.d (4H, C6H4, J = 8.4 Hz). Found,
%: N 4.77, 5.10. C18H19NO2. Calculated, %: N 4.98.
N-(4-Hydroxy-5-isopropyl-2-methylphenyl)-
benzamide (Va). Yield 93%, mp 185–186°C. Found,
%: N 5.02, 5.45. C17H19NO2. Calculated, %: N 5.20.
N-(4-Hydroxy-5-isopropyl-2-methylphenyl)-
4-methylbenzamide (Vb). Yield 95%, mp 150–152°C.
Found, %: N 4.29, 4.78. C18H21NO2. Calculated, %:
N 4.94.
N-(4-Hydroxy-5-isopropyl-2-methylphenyl)-
4-nitrobenzamide (Vc). Yield 73%, mp 190–193°C.
Found, %: N 8.71, 8.89. C17H18N2O4. Calculated, %:
N 8.91.
N-(5-Isopropyl-2-methyl-4-oxocyclohexa-2,5-
dien-1-ylidene)-4-nitrobenzamide (IIc). Yield 76%,
1
mp 154–156°C. H NMR spectrum, δ, ppm: 1.04 d
(6H, 5-CHMe2, J = 7.2 Hz), 2.28 d (3H, 2-Me, J =
1.5 Hz), 2.93–3.07 m (1H, 5-CH), 6.55 q (1H, 6-H, J =
1.2 Hz), 6.62 q (1H, 3-H, J = 1.5 Hz), 8.10–8.37 d.d
(4H, C6H4, J = 9.0 Hz). Found, %: N 8.71, 8.94.
C17H16N2O4. Calculated, %: N 8.97.
N-(4-Hydroxy-2-isopropyl-5-methylphenyl)-
benzamide (VIa). Yield 87%, mp 196–198°C. Found,
%: N 5.05, 5.37. C17H19NO2. Calculated, %: N 5.20.
N-(4-Hydroxy-2-isopropyl-5-methylphenyl)-
4-methylbenzamide (VIb). Yield 81%, mp 163–
165°C. Found, %: N 4.10, 4.67. C18H21NO2. Calculat-
ed, %: N 4.94.
N-(2-Isopropyl-5-methyl-4-oxocyclohexa-2,5-
dien-1-ylidene)benzamide (IIIa). Yield 93%, mp 80–
1
81°C. H NMR spectrum, δ, ppm: 1.28 d (6H,
N-(4-Hydroxy-2-isopropyl-5-methylphenyl)-
4-nitrobenzamide (VIc). Yield 90%, mp 137–140°C.
Found, %: N 8.64, 8.98. C17H18N2O4. Calculated, %:
N 8.91.
2-CHMe2, J = 6.9 Hz), 1.94 d (3H, 5-Me, J = 1.5 Hz),
3.30–3.44 m (1H, 2-CH), 6.56 d (1H, 3-H, J = 0.6 Hz),
6.66 q (1H, 6-H, J = 1.5 Hz), 7.48–7.91 m (5H, Ph).
Found, %: N 5.10, 5.17. C17H17NO2. Calculated, %:
N 5.24.
N-(2,3-Dimethyl-4-oxocyclohexa-2,5-dien-
1-ylidene)benzamide (XXXIa). Yield 93%, mp 94–
N-(2-Isopropyl-5-methyl-4-oxocyclohexa-2,5-di-
en-1-ylidene)-4-methylbenzamide (IIIb). Yield 77%,
1
96°C. H NMR spectrum, δ, ppm: 2.10 d (3H, 3-Me,
1
J = 1.2 Hz), 2.29 d (3H, 2-Me, J = 1.2 Hz), 6.48 d (1H,
5-H, J = 10.2 Hz), 6.83 q (1H, 6-H, J = 10.2 Hz),
7.46–7.90 m (5H, Ph). Found, %: N 5.78, 5.91.
C15H13NO2. Calculated, %: N 5.85.
mp 64–66°C. H NMR spectrum, δ, ppm: 1.27 d (6H,
2-CHMe2, J = 6.6 Hz), 1.93 d (3H, 5-Me, J = 1.5 Hz),
2.44 s (3H, 4-MeC6H4), 3.29–3.43 m (1H, 2-CH),
6.55 d (1H, 3-H, J = 0.6 Hz), 6.65 q (1H, 6-H, J =
1.5 Hz), 7.28–7.79 d.d (4H, C6H4, J = 8.4 Hz). Found,
%: N 4.57, 4.89. C18H19NO2. Calculated, %: N 4.98.
N-(2,3-Dimethyl-4-oxocyclohexa-2,5-dien-
1-ylidene)-4-methylbenzamide (XXXIb). Yield 97%,
1
mp 104–106°C. H NMR spectrum, δ, ppm: 2.10 d
N-(2-Isopropyl-5-methyl-4-oxocyclohexa-2,5-
dien-1-ylidene)-4-nitrobenzamide (IIIc). Yield 85%,
(3H, 3-Me, J = 0.9 Hz), 2.28 d (3H, 2-Me, J = 0.9 Hz),
2.43 s (3H, 4-MeC6H4), 6.47 d (1H, 5-H, J = 10.2 Hz),
6.81 d (1H, 6-H, J = 10.2 Hz), 7.27–7.78 d.d (4H,
C6H4, J = 8.1 Hz). Found, %: N 5.51, 5.67. C16H15NO2.
Calculated, %: N 5.53.
1
mp 124–126°C. H NMR spectrum, δ, ppm: 1.28 d
(6H, 2-CHMe2, J = 6.9 Hz), 1.97 d (3H, 5-Me, J =
1.8 Hz), 3.27–3.41 m (1H, 2-CH), 6.60 d (1H, 3-H, J =
0.6 Hz), 6.66 q (1H, 6-H, J = 1.8 Hz), 8.08–8.37 d.d
(4H, C6H4, J = 9.0 Hz). Found, %: N 8.80, 8.91.
C17H16N2O4. Calculated, %: N 8.97.
N-(4-Hydroxy-2,3-dimethylphenyl)benzamide
(XXXIIa). Yield 89%, mp 210–211°C. Found, %:
N 5.73, 5.84. C15H15NO2. Calculated, %: N 5.80.
N-(4-Hydroxy-2,5-dimethylphenyl)benzamide
(IVa). Yield 73%, mp 257–259°C. Found, %: N 5.15,
5.59. C15H15NO2. Calculated, %: N 5.80.
N-(4-Hydroxy-2,3-dimethylphenyl)-4-methyl-
benzamide (XXXIIb). Yield 95%, mp 224.5–226°C.
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HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... X.
1807
Found, %: N 5.40, 5.49. C16H17NO2. Calculated, %:
N 5.49.
(1H, 3-H, J = 1.2 Hz), 7.48–7.97 m (5H, Ph). 13C NMR
spectrum, δC, ppm: 18.48 (2-Me), 22.00 (5-Me), 58.58
(C6), 64.99 (C5), 128.77 (C2′), 129.62 (C3′), 131.03 (C3),
131.43 (C1′), 134.19 (C4′), 148.65 (C2), 159.80 (C1),
178.49 (NC=O), 188.15 (C4). Found, %: Cl 22.53,
22.90. C15H13Cl2NO2. Calculated, %: Cl 22.86.
Chlorination of quinone imines Ia–Ic, IIa–IIc,
IIIa–IIIc, XVIa–XVIc, XVIIIa–XVIIIc, XXa–XXc,
XXXIa, XXXIb, XXXVa, and XXXVb and amino-
phenols IVa–IVc, Va–Vc, VIa–VIc, Xa–Xc, XIIa–
XIIc, XIVa–XIVc, XXXIIa, XXXIIb, XXXIIIa, and
XXXIIIb (general procedure). A stream of dry chlo-
rine was passed at a flow rate of 15–20 ml/min through
a solution of 2 mmol of the corresponding quinone
imine or aminophenol in 3 ml of chloroform, acetic
acid, dimethylformamide, or dimethylformamide–
acetic acid mixture (1:5), maintained at 30–40°C. The
amount of chlorine was controlled by the gain in
weight until a substrate-to-chlorine ratio of 1:1 to 1:3.
The precipitate was filtered off and recrystallized from
acetic acid.
N-(3-Chloro-4-hydroxy-2,5-dimethylphenyl)-
benzamide (Xa). Yield 61%, mp 218–219°C. Found,
%: Cl 12.46, 12.81. C15H14ClNO2. Calculated, %:
Cl 12.86.
N-(3-Chloro-4-hydroxy-2,5-dimethylphenyl)-
4-methylbenzamide (Xb). Yield 58%, mp 197–198°C.
Found, %: Cl 11.92, 12.10. C16H16ClNO2. Calculated,
%: Cl 12.24.
N-(3-Chloro-4-hydroxy-2,5-dimethylphenyl)-
4-nitrobenzamide (Xc). Yield 70%, mp 241–242°C.
Found, %: Cl 10.69, 11.12. C15H13ClN2O4. Calculated,
%: Cl 11.05.
Compound VII was obtained by chlorination of
quinone imine Ia in chloroform at a substrate-to-
chlorine ratio of 1:3; compounds Xa–Xc, XIIa–XIIc,
and XIVa–XIVc were obtained by chlorination of
aminophenols IVa–IVc, Va–Vc, and VIa–VIc in
AcOH or DMF–AcOH (1:5) at a substrate-to-chlorine
ratio of 1 : 1; compounds XVIa–XVIc, XVIIIa–
XVIIIc, and XXa–XXc were obtained by chlorination
of quinone imines Ia–Ic, IIa–IIc, and IIIa–IIIc in
AcOH at a substrate-to-chlorine ratio of 1:2; com-
pounds XXIIIa–XXIIIc, XXVa–XXVc, and XXVIa–
XXVIc were obtained by chlorination of quinone
imines Ia–Ic, IIa–IIc, and IIIa–IIIc or aminophenols
IVa–IVc, Va–Vc, and VIa–VIc in DMF–AcOH (1:5)
at a substrate-to-chlorine ratio of 1:3 or by chlorina-
tion of aminophenols Xa–Xc, XIIa–XIIc, and XIVa–
XIVc or quinone imines XVIa–XVIc, XVIIIa–
XVIIIc, and XXa–XXc in AcOH or DMF–AcOH 1:5
at a substrate-to-chlorine ratio of 1 :1; compounds
XXXIIIa and XXXIIIb were obtained by chlorination
of aminophenols XXXIIa and XXXIIb in AcOH,
DMF, or DMF–AcOH (1:5) at a substrate-to-chlorine
ratio of 1:1; compounds XXXVIIa and XXXVIIb
were obtained by chlorination of aminophenols
XXXIIIa and XXXIIIb or quinone imines XXXIa,
XXXIb, XXXVa, and XXXVb in DMF or DMF–
AcOH (1:5) at a substrate-to-chlorine ratio of 1:1;
compound XL was obtained by chlorination of qui-
none imines XXXIa and XXXIb in CHCl3.
N-(3-Chloro-4-hydroxy-5-isopropyl-2-methyl-
phenyl)benzamide (XIIa). Yield 57%, mp 173–
175°C. Found, %: Cl 11.29, 11.60. C17H18ClNO2. Cal-
culated, %: Cl 11.67.
N-(3-Chloro-4-hydroxy-5-isopropyl-2-methyl-
phenyl)-4-methylbenzamide (XIIb). Yield 45%,
mp 192–194°C. Found, %: Cl 10.63, 11.04.
C18H20ClNO2. Calculated, %: Cl 11.16.
N-(3-Chloro-4-hydroxy-5-isopropyl-2-methyl-
phenyl)-4-nitrobenzamide (XIIc). Yield 74%,
mp 240–242.5°C. Found, %: Cl 9.70, 10.20.
C17H17ClN2O4. Calculated, %: Cl 10.16.
N-(3-Chloro-4-hydroxy-2-isopropyl-5-methyl-
phenyl)benzamide (XIVa). Yield 32%, mp 182–
184°C. Found, %: Cl 11.30, 11.75. C17H18ClNO2. Cal-
culated, %: Cl 11.67.
N-(3-Chloro-4-hydroxy-2-isopropyl-5-methyl-
phenyl)-4-methylbenzamide (XIVb). Yield 69%,
mp 202–204°C. Found, %: Cl 11.24, 11.58.
C18H20ClNO2. Calculated, %: Cl 11.16.
N-(3-Chloro-4-hydroxy-2-isopropyl-5-methyl-
phenyl)-4-nitrobenzamide (XIVc). Yield 69%,
mp 173–174°C. Found, %: Cl 9. 89, 10. 32.
C17H17ClN2O4. Calculated, %: Cl 10.16.
N-(3-Chloro-2,5-dimethyl-4-oxocyclohexa-2,5-di-
en-1-ylidene)benzamide (XVIa). Yield 87%, mp 101–
1
103°C. H NMR spectrum, δ, ppm: 2.01 d (3H, 5-Me,
N-(5,6-Dichloro-2,5-dimethyl-4-oxocyclohex-
2-en-1-ylidene)benzamide (VII). Yield 60%, mp 126–
128°C. 1H NMR spectrum, δ, ppm: 1.79 s (3H, 5-Me),
2.30 d (3H, 2-Me, J = 1.2 Hz), 4.83 s (1H, 6-H), 6.52 q
J = 1.2 Hz), 2.44 s (3H, 2-Me), 6.71 q (1H, 6-H, J =
1.2 Hz), 7.48–7.90 m (5H, Ph). Found, %: Cl 12.88,
13.32. C15H12ClNO2. Calculated, %: Cl 12.95.
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AVDEENKO et al.
1808
N-(3-Chloro-2,5-dimethyl-4-oxocyclohexa-2,5-
3.72–3.86 m (1H, 2-CH), 6.64 q (1H, 6-H, J = 1.2 Hz),
7.29–7.77 d (4H, C6H4, J = 8.4 Hz). Found, %:
Cl 11.01, 11.71. C18H18ClNO2. Calculated, %: Cl 11.23.
dien-1-ylidene)-4-methylbenzamide (XVIb). Yield
1
73%, mp 140–142°C. H NMR spectrum, δ, ppm:
2.00 d (3H, 5-Me, J = 1.5 Hz), 2.44 s (3H, 4-MeC6H4),
2.44 s (3H, 2-Me), 6.69 q (1H, 6-H, J = 1.5 Hz), 7.28–
7.79 d.d (4H, C6H4, J = 8.1 Hz). Found, %: Cl 12.08,
12.49. C16H14ClNO2. Calculated, %: Cl 12.32.
N-(3-Chloro-2-isopropyl-5-methyl-4-oxocyclo-
hexa-2,5-dien-1-ylidene)-4-nitrobenzamide (XXc).
1
Yield 61%, mp 136–138°C. H NMR spectrum, δ,
ppm: 1.48 d (6H, 2-CHMe2, J = 7.2 Hz), 2.02 d (3H,
5-Me, J = 1.5 Hz), 3.72–3.86 m (1H, 2-CH), 6.65 q
(1H, 6-H, J = 1.5 Hz), 8.06–8.38 d.d (4H, C6H4, J =
9.0 Hz). Found, %: Cl 9.76, 10.25. C17H15ClN2O4. Cal-
culated, %: Cl 10.22.
N-(3-Chloro-2,5-dimethyl-4-oxocyclohexa-2,5-di-
en-1-ylidene)-4-nitrobenzamide (XVIc). Yield 63%,
1
mp 196–198°C. H NMR spectrum, δ, ppm: 2.05 d
(3H, 5-Me, J = 1.8 Hz), 2.46 s (3H, 2-Me), 6.72 q (1H,
6-H, J = 1.8 Hz), 8.09–8.36 d.d (4H, C6H4, J = 9.3 Hz).
Found, %: Cl 10.93, 11.25. C15H11ClN2O4. Calculated,
%: Cl 11.12.
N-(3,5,6-Trichloro-2,5-dimethyl-4-oxocyclohex-
2-en-1-ylidene)benzamide (XXIIIa). Yield 11%,
1
mp 128–129°C. H NMR spectrum, δ, ppm: 1.86 s
N-(3-Chloro-5-isopropyl-2-methyl-4-oxocyclo-
hexa-2,5-dien-1-ylidene)benzamide (XVIIIa). Yield
(3H, 5-Me), 2.47 s (3H, 2-Me), 4.87 s (1H, 6-H), 7.48–
7.97 m (5H, Ph). 13C NMR spectrum, δC, ppm: 16.57
(2-Me), 23.18 (5-Me), 58.05 (C6), 64.65 (C5), 128.79
(C2′), 129.59 (C3′), 131.28 (C1′), 134.29 (C4′), 137.15
(C3), 144.89 (C2), 158.42 (C1), 178.12 (NC=O), 181.63
(C4). Found, %: Cl 30.94, 31.81. C15H12Cl3NO2. Cal-
culated, %: Cl 30.86.
1
57%, mp 94–96°C. H NMR spectrum, δ, ppm: 1.04 d
(6H, 5-CHMe2, J = 6.9 Hz), 2.44 s (3H, 2-Me), 2.96–
3.10 m (1H, 5-CH), 6.61 d (1H, 6-H, J = 1.2 Hz),
7.48–7.91 m (5H, Ph). Found, %: Cl 11.80, 12.32.
C17H16ClNO2. Calculated, %: Cl 11.75.
N-(3-Chloro-5-isopropyl-2-methyl-4-oxocyclo-
4-Methyl-N-(3,5,6-trichloro-2,5-dimethyl-4-oxo-
cyclohex-2-en-1-ylidene)benzamide (XXIIIb). Yield
59%, mp 90–91°C. H NMR spectrum, δ, ppm: 1.85 s
hexa-2,5-dien-1-ylidene)-4-methylbenzamide
1
1
(XVIIIb). Yield 61%, mp 96–98°C. H NMR spec-
trum, δ, ppm: 1.03 d (6H, 5-CHMe2, J = 6.9 Hz),
2.43 s (3H, 2-Me), 2.44 s (3H, 4-MeC6H4), 2.96–3.10
(1H, 5-CH), 6.60 d (1H, 6-H, J = 0.9 Hz), 7.28–
7.79 d.d (4H, C6H4, J = 8.1 Hz). Found, %: Cl 11.04,
11.59. C18H18ClNO2. Calculated, %: Cl 11.23.
(3H, 5-Me), 2.44 s (3H, 4-MeC6H4, J = 8.4 Hz), 2.46 s
(3H, 2-Me), 4.86 s (1H, 6-H), 7.28–7.85 d.d (4H,
C6H4, J = 8.4 Hz). 13C NMR spectrum, δC, ppm: 16.61
(2-Me), 21.83 (MeC6H4), 22.58 (5-Me), 58.20 (C6),
64.68 (C5), 128.54 (C1′), 129.53 (C2′), 129.73 (C3′),
137.12 (C3), 145.04 (C4′), 145.42 (C2), 158.20 (C1),
178.13 (NC=O), 181.72 (C4). Found, %: Cl 29.31,
29.79. C16H14Cl3NO2. Calculated, %: Cl 29.66.
N-(3-Chloro-5-isopropyl-2-methyl-4-oxocyclo-
hexa-2,5-dien-1-ylidene)-4-nitrobenzamide
1
(XVIIIc). Yield 60%, mp 169–170°C. H NMR spec-
trum, δ, ppm: 1.07 d (6H, 5-CHMe2, J = 6.6 Hz),
2.45 s (3H, 2-Me), 2.98–3.12 m (1H, 5-CH), 6.61 d
(1H, 6-H, J = 0.9 Hz), 8.10–8.37 d.d (4H, C6H4, J =
9.3 Hz). Found, %: Cl 9.88, 10.34. C17H15ClN2O4. Cal-
culated, %: Cl 10.22.
4-Nitro-N-(3,5,6-trichloro-2,5-dimethyl-4-oxo-
cyclohex-2-en-1-ylidene)benzamide (XXIIIc). Yield
59%, mp 160–162°C. H NMR spectrum, δ, ppm:
1.88 s (3H, 5-Me), 2.48 s (3H, 2-Me), 4.88 s (1H,
6-H), 8.13–8.37 d.d (4H, C6H4, J = 9.0 Hz). Found, %:
Cl 26.98, 27.33. C15H11Cl3N2O4. Calculated, %:
Cl 27.30.
1
N-(3-Chloro-2-isopropyl-5-methyl-4-oxocyclo-
hexa-2,5-dien-1-ylidene)benzamide (XXa). Yield
1
31%, mp 84–86°C. H NMR spectrum, δ, ppm: 1.48 d
N-(3,5,6-Trichloro-5-isopropyl-2-methyl-4-oxo-
cyclohex-2-en-1-ylidene)benzamide (XXVa). Yield
(6H, 2-CHMe2, J = 6.9 Hz), 1.99 d (3H, 5-Me, J =
1.5 Hz), 3.72–3.86 m (1H, 2-CH), 6.65 q (1H, 6-H, J =
1.5 Hz), 7.48–7.89 m (5H, Ph). Found, %: Cl 11.40,
11.79. C17H16ClNO2. Calculated, %: Cl 11.75.
1
43%, mp 139–141°C. H NMR spectrum, δ, ppm:
0.88–1.11 d.d (6H, 5-CHMe2, J = 6.3 Hz), 2.24–
2.38 m (1H, 5-CH), 2.45 s (3H, 2-Me), 5.10 s (1H,
6-H), 7.48–7.93 m (5H, Ph). 13C NMR spectrum, δC,
ppm: 16.36 and 17.20 (CHMe2), 18.77 (2-Me), 36.08
(CHMe2), 59.96 (C6), 82.86 (C5), 128.88 (C2′), 129.54
(C3′), 130.90 (C1′), 134.50 (C4′), 138.69 (C3), 144.54
(C2), 158.76 (C1), 178.23 (NC=O), 183.50 (C4). Found,
N-(3-Chloro-2-isopropyl-5-methyl-4-oxocyclo-
hexa-2,5-dien-1-ylidene)-4-methylbenzamide
1
(XXb). Yield 21%, mp 102–104°C. H NMR spec-
trum, δ, ppm: 1.47 d (6H, 2-CHMe2, J = 7.5 Hz),
1.98 d (3H, 5-Me, J = 1.2 Hz), 2.44 s (3H, 4-CH3C6H4),
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 12 2009

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... X.
1809
%: Cl 28.10, 28.37. C17H16Cl3NO2. Calculated, %:
Cl 28.54.
%: Cl 25.04, 25.40. C17H15Cl3N2O4. Calculated, %:
Cl 25.46.
N-(5-Chloro-4-hydroxy-2,3-dimethylphenyl)-
benzamide (XXXIIIa). Yield 80%, mp 176–178°C.
Found, %: Cl 12.65, 12.89. C15H14ClNO2. Calculated,
%: Cl 12.86.
4-Methyl-N-(3,5,6-trichloro-5-isopropyl-2-
methyl-4-oxocyclohex-2-en-1-ylidene)benzamide
1
(XXVb). Yield 47%, mp 168–170°C. H NMR spec-
trum, δ, ppm: 0.87–1.11 d.d (6H, 5-CHMe2, J =
6.6 Hz), 2.23–2.37 m (1H, 5-CH), 2.44 s (3H,
4-MeC6H4), 2.44 s (3H, 2-Me), 5.09 s (1H, 6-H), 7.28–
7.82 d.d (4H, C6H4, J = 8.4 Hz). Found, %: Cl 27.45,
27.78. C18H18Cl3NO2. Calculated, %: Cl 27.50.
N-(5-Chloro-4-hydroxy-2,3-dimethylphenyl)-
4-methylbenzamide (XXXIIIb). Yield 53%, mp 226–
228°C. Found, %: Cl 12.01, 12.29. C16H16ClNO2. Cal-
culated, %: Cl 12.24.
4-Nitro-N-(3,5,6-trichloro-5-isopropyl-2-methyl-
N-(5-Chloro-2,3-dimethyl-4-oxocyclohexa-
2,5-dien-1-ylidene)benzamide (XXXVa). Yield 15%,
mp 136–138°C. H NMR spectrum, δ, ppm: 2.16 d
4-oxocyclohex-2-en-1-ylidene)benzamide (XXVc).
1
1
Yield 60%, mp 157–159°C. H NMR spectrum, δ,
(3H, 3-Me, J = 1.2 Hz), 2.30 d (3H, 2-Me, J = 1.2 Hz),
7.05 s (1H, 6-H), 7.47–7.90 m (5H, Ph). Found, %:
Cl 12.84, 12.99. C15H12ClNO2. Calculated, %: Cl 12.95.
ppm: 0.90–1.17 d.d (6H, 5-CHMe2, J = 6.6 Hz), 2.25–
2.39 m (1H, 5-CH), 2.47 s (3H, 2-Me), 5.14 s (1H,
6-H), 8.10–8.38 d.d (4H, C6H4, J = 9.0 Hz). Found,
%: Cl 25.10, 25.59. C17H15Cl3N2O4. Calculated, %:
Cl 25.46.
N-(5-Chloro-2,3-dimethyl-4-oxocyclohexa-2,5-
dien-1-ylidene)-4-methylbenzamide (XXXVb). Yield
1
21%, mp 169–170°C. H NMR spectrum, δ, ppm:
N-(3,5,6-Trichloro-2-isopropyl-5-methyl-4-oxo-
cyclohex-2-en-1-ylidene)benzamide (XXVIa). Yield
2.15 d (3H, 3-Me, J = 1.2 Hz), 2.30 d (3H, 2-Me, J =
1.2 Hz), 2.44 s (3H, 4-MeC6H4), 7.03 s (1H, 6-H),
7.28–7.78 d.d (4H, C6H4, J = 8.1 Hz). Found, %:
Cl 12.31, 12.45. C16H14ClNO2. Calculated, %: Cl 12.32.
1
84%, mp 122–123°C. H NMR spectrum, δ, ppm:
1.45–1.51 d.d (6H, 2-CHMe2, J = 7.2 Hz), 1.83 s (3H,
5-Me), 3.63–3.77 m (1H, 2-CH), 4.79 s (1H, 6-H),
7.48–7.96 m (5H, Ph). 13C NMR spectrum, δC, ppm:
18.78 and 19.86 (CHMe2), 22.52 (5-Me), 31.81
(CHMe2), 59.19 (C6), 64.39 (C5), 128.81 (C2′), 129.61
(C3′), 131.35 (C1′), 134.24 (C4′), 135.97 (C3), 152.00
(C2), 157.27 (C1), 177.63 (NC=O), 182.10 (C4). Found,
%: Cl 28.12, 28.51. C17H16Cl3NO2. Calculated, %:
Cl 28.54.
N-(3,5,6-Trichloro-5,6-dimethyl-4-oxocyclohex-
2-en-1-ylidene)benzamide (XXXVIIa). Yield 11%,
1
mp 61–63°C. H NMR spectrum, δ, ppm: 2.04 s
(3H, 5-Me), 2.14 s (3H, 6-Me), 7.03 s (1H, 2-H), 7.48–
7.93 m (5H, Ph). Found, %: Cl 30.76, 30.79.
C15H12Cl3NO2. Calculated, %: Cl 30.86.
4-Methyl-N-(3,5,6-trichloro-5,6-dimethyl-4-oxo-
cyclohex-2-en-1-ylidene)benzamide (XXXVIIb).
Yield 68%, mp 79–80°C. H NMR spectrum, δ, ppm:
2.04 s (3H, 5-Me), 2.13 s (3H, 6-Me), 2.44 s (3H,
4-MeC6H4), 7.01 s (1H, 2-H), 7.29–7.82 d.d (4H,
C6H4, J = 8.4 Hz). Found, %: Cl 29.58, 29.68.
C16H14Cl3NO2. Calculated, %: Cl 29.66.
4-Methyl-N-(3,5,6-trichloro-2-isopropyl-5-
1
methyl-4-oxocyclohex-2-en-1-ylidene)benzamide
1
(XXVIb). Yield 63%, mp 138–140°C. H NMR spec-
trum, δ, ppm: 1.44–1.51 d.d (6H, 2-CHMe2, J =
7.2 Hz), 1.83 s (3H, 5-Me), 2.44 s (3H, 4-MeC6H4),
3.62–3.76 m (1H, 2-CH), 4.78 s (1H, 6-H), 7.29–
7.84 d.d (4H, C6H4, J = 8.1 Hz). 13C NMR spectrum,
δC, ppm: 18.78 and 19.85 (CHMe2), 21.81 (4-MeC6H4),
22.52 (5-Me), 31.78 (CHMe2), 59.13 (C6), 64.40 (C5),
128.70 (C1′), 129.52 (C2′), 129.69 (C3′), 135.79 (C3),
145.31 (C4′), 152.09 (C2), 157.01 (C1), 177.59 (NC=O),
182.14 (C4). Found, %: Cl 27.41, 27.93. C18H18Cl3NO2.
Calculated, %: Cl 27.50.
5,6-Dichloro-2,3-dimethylcyclohex-2-ene-1,4-
1
dione (XL). Yield 83%, sublimes at 158°C. H NMR
spectrum, δ, ppm: 2.09 s (6H, Me), 4.68 s (2H, 5-H,
6-H). Found, %: Cl 34.10, 34.22. C8H8Cl2O2. Calculat-
ed, %: Cl 34.29.
Bromination of quinone imines Ia–Ic, IIa–IIc,
IIIa–IIIc, XVIIa–XVIIc, XIXa–XIXc, XXIa–XXIc,
XXXIa, XXXIb, XXXVIa, and XXXVIb and
aminophenols IVa–IVc, Va–Vc, VIa–VIc, XIa–XIc,
XIIIa–XIIIc, XVa–XVc, XXXIIa, XXXIIb,
XXXIVa, and XXXIVb (general procedure). A solu-
tion of bromine in chloroform, acetic acid, dimethyl-
formamide, or dimethylformamide–acetic acid (1:5)
4-Nitro-N-(3,5,6-trichloro-2-isopropyl-5-methyl-
4-oxocyclohex-2-en-1-ylidene)benzamide (XXVIc).
1
Yield 70%, mp 159–162°C. H NMR spectrum, δ,
ppm: 1.44–1.52 d.d (6H, 2-CHMe2, J = 7.2 Hz), 1.85 s
(3H, 5-Me), 3.62–3.76 m (1H, 2-CH), 4.78 s (1H,
6-H), 8.11–8.38 d.d (4H, C6H4, J = 9.0 Hz). Found,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 12 2009

AVDEENKO et al.
1810
1
was added dropwise under stirring at 30–40°C to
a solution of 2 mmol of the corresponding substrate in
3 ml of the same solvent until a required substrate-to-
bromine ratio was attained (1:1 to 1:10). The precip-
itate was filtered off and recrystallized from acetic
acid.
Yield 95%, mp 119–121°C. H NMR spectrum, δ,
ppm: 1.26–1.31 d.d (6H, 2-CHMe2, J = 6.9 Hz), 1.97 s
(3H, 5-Me), 2.44 s (3H, 4-MeC6H4), 3.25–3.39 m (1H,
2-CHMe2), 5.07 s (1H, 6-H), 6.40 s (1H, 3-H), 7.27–
7.88 d.d (4H, C6H4, J = 8.1 Hz). 13C NMR spectrum,
δC, ppm: 20.82 and 21.45 (CHMe2), 21.86 (4-MeC6H4),
24.73 (5-Me), 28.35 (CHMe2), 49.37 (C6), 57.52 (C5),
127.11 (C3), 128.79 (C1′), 129.44 (C2′), 129.73 (C3′),
145.16 (C4′), 157.80 (C2), 158.87 (C1), 178.75 (NC=O),
188.94 (C4). Found, %: Br 36.01, 36.39. C18H19Br2NO2.
Calculated, %: Br 36.22.
Compounds VIIIb and VIIIc were obtained by
bromination of quinone imines IIIb and IIIc in AcOH
at a substrate-to-bromine ratio of 1:3; compound IX
was obtained by bromination of quinone imine IIc in
DMF–AcOH (1:5) at a substrate-to-bromine ratio of
1:1; compounds XIa–XIc, XIIIa–XIIIc, and XVa–
XVc were obtained by bromination of quinone imines
Ia–Ic, IIa–IIc, and IIIa–IIIc in AcOH or amino-
phenols IVa–IVc, Va–Vc, and VIa–VIc in AcOH,
DMF–AcOH (1:5), DMF, or CHCl3 at a substrate-to-
bromine ratio of 1 :1; compounds XVIIa–XVIIc,
XIXa–XIXc, and XXIa–XXIc were obtained by
bromination of quinone imines Ia–Ic, IIa–IIc, and
IIIa–IIIc or aminophenols IVa–IVc, Va–Vc, and VIa–
VIc in DMF at a substrate-to-bromine ratio of 1:2;
compounds XXIIa–XXIIc were obtained by bromina-
tion of quinone imines XVa–XVc in DMF at a sub-
strate-to-bromine ratio of 1:2; compounds XXIVa,
XXIVc, XXVIIa, and XXVIIc were obtained by
bromination of quinone imines Ia, Ic, IIIa, IIIc,
XVIIa, XVIIc, XXIa, and XXIc or aminophenols IVa,
IVc, VIa, VIc, XIa, XIc, XVa, and XVc in AcOH or
DMF–AcOH (1:5) at a substrate-to-bromine ratio of
1:5; compound XXVIII was obtained by bromination
of aminophenol XIa in AcOH at a substrate-to-
bromine ratio of 1:10; compounds XXIX and XXX
were obtained by bromination of aminophenols XIa
and XIIIa in DMF at a substrate-to-bromine ratio of
1 :6; compounds XXXIVa and XXXIVb were ob-
tained by bromination of quinone imines XXXIa and
XXXIb or aminophenols XXXIIa or XXXIIb in
CHCl3 or AcOH at a substrate-to-bromine ratio of 1:1;
compounds XXXVIa and XXXVIb were obtained by
bromination of quinone imines XXXIa and XXXIb or
aminophenols XXXIIa and XXXIIb in AcOH or
DMF–AcOH (1:5) at a substrate-to-bromine ratio of
1:5; compounds XXXVIIIa, XXXVIIIc, and XXXIX
were obtained by bromination of quinone imines
XXXIa, XXXIb, XXXVIa, and XXXVIb or amino-
phenols XXXIIa, XXXIIb, XXXIVa, and XXXIVb in
DMF–AcOH (1 :5) at a substrate-to-bromine ratio
of 1:10; we failed to separate compounds XXXVIIIa
and XXXIX.
N-(5,6-Dibromo-2-isopropyl-5-methyl-4-oxo-
cyclohex-2-en-1-ylidene)-4-nitrobenzamide (VIIIc).
1
Yield 66%, mp 144–146°C. H NMR spectrum, δ,
ppm: 1.27–1.33 d.d (6H, 2-CHMe2, J = 6.9 Hz), 2.00 s
(3H, 5-Me), 3.23–3.37 m (1H, 2-CH), 5.08 s (1H,
6-H), 6.46 s (1H, 3-H), 8.15–8.37 d.d (4H, C6H4, J =
8.7 Hz). Found, %: Br 33.45, 33.91. C17H16Br2N2O4.
Calculated, %: Br 33.85.
N-(5,6-Dibromo-3-isopropyl-6-methyl-4-oxo-
cyclohex-2-en-1-ylidene)-4-nitrobenzamide (IX).
1
Yield 35%, mp 119–120°C. H NMR spectrum, δ,
ppm: 1.02–1.08 d.d (6H, 3-CHMe2, J = 6.9 Hz), 2.31 s
(3H, 6-Me), 2.91–3.05 m (1H, 3-CH), 4.92 s (1H,
5-H), 6.42 s (1H, 2-H), 8.12–8.37 d.d (4H, C6H4, J =
9.0 Hz). Found, %: Br 33.54, 33.91. C17H16Br2N2O4.
Calculated, %: Br 33.85.
N-(3-Bromo-4-hydroxy-2,5-dimethylphenyl)-
benzamide (XIa). Yield 98%, mp 204–206°C. Found,
%: Br 24.42, 24.59. C15H14BrNO2. Calculated, %:
Br 24.96.
N-(3-Bromo-4-hydroxy-2,5-dimethylphenyl)-4-
methylbenzamide (XIb). Yield 86%, mp 201–203°C.
Found, %: Br 23.55, 24.01. C16H16BrNO2. Calculated,
%: Br 23.91.
N-(3-Bromo-4-hydroxy-2,5-dimethylphenyl)-4-
nitrobenzamide (XIc). Yield 78%, mp 242–244.5°C.
Found, %: Br 21.49, 21.78. C15H13BrN2O4. Calculated,
%: Br 21.88.
N-(3-Bromo-4-hydroxy-5-isopropyl-2-methyl-
phenyl)benzamide (XIIIa). Yield 95%, mp 173–
175°C. Found, %: Br 22.30, 22.81. C17H18BrNO2. Cal-
culated, %: Br 22.94.
N-(3-Bromo-4-hydroxy-5-isopropyl-2-methyl-
phenyl)-4-methylbenzamide (XIIIb). Yield 59%,
mp 148–150°C. Found, %: Br 21.49, 21.76.
C18H20BrNO2. Calculated, %: Br 22.06.
N-(5,6-Dibromo-2-isopropyl-5-methyl-4-oxocy-
clohex-2-en-1-ylidene)-4-methylbenzamide (VIIIb).
N-(3-Bromo-4-hydroxy-5-isopropyl-2-methyl-
phenyl)-4-nitrobenzamide (XIIIc). Yield 88%,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 12 2009

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... X.
1811
mp 232– 233.5°C. Found, %: Br 20.03, 20.44.
C17H17BrN2O4. Calculated, %: Br 20.32.
7.28–7.79 d.d (4H, C6H4, J = 8.4 Hz). Found, %:
Br 21.74, 22.22. C18H18BrNO2. Calculated, %:
Br 22.18.
N-(3-Bromo-4-hydroxy-2-isopropyl-5-methyl-
phenyl)benzamide (XVa). Yield 75%, mp 198–200°C.
Found, %: Br 22.04, 22.73. C17H18BrNO2. Calculated,
%: Br 22.94.
N-(3-Bromo-5-isopropyl-2-methyl-4-oxocyclo-
hexa-2,5-dien-1-ylidene)-4-nitrobenzamide (XIXc).
1
Yield 83%, mp 166–167°C. H NMR spectrum, δ,
ppm: 2.06 d (6H, 5-CHMe2, J = 6.9 Hz), 2.49 s (3H,
2-Me), 3.00–3.14 m (1H, 5-CH), 6.60 d (1H, 6-H, J =
0.9 Hz), 8.09–8.37 d.d (4H, C6H4, J = 9.0 Hz). Found,
%: Br 20.03, 20.46. C17H15BrN2O4. Calculated, %:
Br 20.42.
N-(3-Bromo-4-hydroxy-2-isopropyl-5-methyl-
phenyl)-4-methylbenzamide (XVb). Yield 99%,
mp 218–220°C. Found, %: Br 21.60, 22.04.
C18H20BrNO2. Calculated, %: Br 22.06.
N-(3-Bromo-4-hydroxy-5-isopropyl-2-methyl-
phenyl)-4-nitrobenzamide (XVc). Yield 96%,
mp 202–203°C. Found, %: Br 20.10, 20.49.
C17H17BrN2O4. Calculated, %: Br 20.32.
N-(3-Bromo-2-isopropyl-5-methyl-4-oxocyclo-
hexa-2,5-dien-1-ylidene)benzamide (XXIa). Yield
1
13%, mp 92–94°C. H NMR spectrum, δ, ppm: 1.50 d
(6H, 2-CHMe2, J = 6.9 Hz), 1.99 d (3H, 5-Me, J =
1.5 Hz), 3.71–3.85 m (1H, 2-CH), 6.63 q (1H, 6-H, J =
1.5 Hz), 7.49–7.89 m (5H, Ph). Found, %: Br 23.04,
24.02. C17H16BrNO2. Calculated, %: Br 23.08.
N-(3-Bromo-2,5-dimethyl-4-oxocyclohexa-
2,5-dien-1-ylidene)benzamide (XVIIa). Yield 36%,
mp 116–118°C. H NMR spectrum, δ, ppm: 2.02 d
(3H, 5-Me, J = 1.5 Hz), 2.49 s (3H, 2-Me), 6.70 q
(1H, 6-H, J = 1.5 Hz), 7.48–7.90 m (5H, Ph). Found,
%: Br 23.83, 24.65. C15H12BrNO2. Calculated, %:
Br 25.11.
1
N-(3-Bromo-2-isopropyl-5-methyl-4-oxocyclo-
hexa-2,5-dien-1-ylidene)-4-methylbenzamide
1
(XXIb). Yield 19%, mp 110–112°C. H NMR spec-
trum, δ, ppm: 1.49 d (6H, 2-CHMe2, J = 6.6 Hz),
1.98 d (3H, 5-Me, J = 1.2 Hz), 2.44 s (3H, 4-CH3C6H4),
3.71–3.85 m (1H, 2-CH), 6.62 q (1H, 6-H, J = 1.2 Hz),
7.29–7.77 d.d (4H, C6H4, J = 8.4 Hz). Found, %:
Br 22.11, 22.35. C18H18BrNO2. Calculated, %:
Br 22.18.
N-(3-Bromo-2,5-dimethyl-4-oxocyclohexa-2,5-
dien-1-ylidene)-4-methylbenzamide (XVIIb). Yield
23%, mp 110–112°C. H NMR spectrum, δ, ppm:
2.01 d (3H, 5-Me, J = 1.5 Hz), 2.44 s (3H,
4-CH3C6H4), 2.48 s (3H, 2-Me), 6.69 q (1H, 6-H, J =
1.5 Hz), 7.28–7.79 d.d (4H, C6H4, J = 7.8 Hz). Found,
%: Br 23.41, 23.87. C16H14BrNO2. Calculated, %:
Br 24.05.
1
N-(3-Bromo-2-isopropyl-5-methyl-4-oxocyclo-
hexa-2,5-dien-1-ylidene)-4-nitrobenzamide (XXIc).
1
Yield 20%, mp 103–105.5°C. H NMR spectrum, δ,
N-(3-Bromo-2,5-dimethyl-4-oxocyclohexa-2,5-di-
en-1-ylidene)-4-nitrobenzamide (XVIIc). Yield 61%,
ppm: 1.50 d (6H, 2-CHMe2, J = 6.9 Hz), 2.03 d (3H,
5-Me, J = 1.5 Hz), 3.75–3.89 m (1H, 2-CH), 6.62 q
(1H, 6-H, J = 1.5 Hz), 8.06–8.38 d.d (4H, C6H4, J =
9.0 Hz). Found, %: Br 20.10, 20.46. C17H15BrN2O4.
Calculated, %: Br 20.42.
1
mp 192–194°C. H NMR spectrum, δ, ppm: 2.06 d
(3H, 5-Me, J = 1.5 Hz), 2.50 s (3H, 2-Me), 6.71 q (1H,
6-H, J = 1.5 Hz), 8.09–8.37 d.d (4H, C6H4, J = 9.0 Hz).
Found, %: Br 21.53, 21.89. C15H11BrN2O4. Calculated,
%: Br 22.00.
N-(5,5,6-Tribromo-3-isopropyl-6-methyl-4-oxo-
cyclohex-2-en-1-ylidene)benzamide (XXIIa).
1H NMR spectrum, δ, ppm: 1.00–1.10 d.d (6H,
3-CHMe2, J = 6.9 Hz), 2.10 s (3H, 6-Me), 2.95–3.09 m
(1H, 3-CH), 6.58 s (1H, 2-H), 7.43–7.92 m (5H, Ph).
N-(3-Bromo-5-isopropyl-2-methyl-4-oxocyclo-
hexa-2,5-dien-1-ylidene)benzamide (XIXa). Yield
1
20%, mp 92–93°C. H NMR spectrum, δ, ppm: 1.04 d
(6H, 5-CHMe2, J = 6.9 Hz), 2.48 s (3H, 2-Me), 2.97–
3.11 m (1H, 5-CH), 6.60 d (1H, 6-H), 7.28–7.79 m
(5H, Ph). Found, %: Br 23.01, 23.25. C17H16BrNO2.
Calculated, %: Br 23.08.
4-Methyl-N-(5,5,6-tribromo-3-isopropyl-6-
methyl-4-oxocyclohex-2-en-1-ylidene)benzamide
1
(XXIIb). Yield 35%, mp 134–136°C. H NMR spec-
N-(3-Bromo-5-isopropyl-2-methyl-4-oxocyclo-
trum, δ, ppm: 1.00–1.09 d.d (6H, 3-CHMe2, J =
6.6 Hz), 2.08 s (3H, 6-Me), 2.40 s (3H, 4-CH3C6H4),
2.94–3.08 m (1H, 3-CH), 6.58 s (1H, 2-H), 7.21–
7.80 d.d (4H, C6H4, J = 8.1 Hz). 13C NMR spectrum,
δC, ppm: 17.58 (6-Me), 20.60 and 20.71 (CHMe2),
21.75 (4-MeC6H4), 28.60 (CHMe2), 70.47 (C6), 88.50
hexa-2,5-dien-1-ylidene)-4-methylbenzamide
1
(XIXb). Yield 35%, mp 100–101°C. H NMR spec-
trum, δ, ppm: 1.03 d (6H, 5-CHMe2, J = 6.9 Hz),
2.44 s (3H, 4-MeC6H4), 2.48 s (3H, 2-Me), 2.96–
3.10 m (1H, 5-CH), 6.59 d (1H, 6-H, J = 0.9 Hz),
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 12 2009

AVDEENKO et al.
1812
(C5), 125.19 (C1′), 129.39 (C2′), 130.08 (C3′), 130.83
(C2), 145.21 (C4′), 152.34 (C3), 163.77 (C1), 183.20
(NC=O), 189.46 (C4). Found, %: Br 45.57, 46.03.
C18H18Br3NO2. Calculated, %: Br 46.09.
ppm: 2.16 s (3H, 3-Me), 4.39 q (2H, CH2Br, J = 3.3,
9.0 Hz), 7.41–7.93 m (5H, Ph). 13C NMR spectrum, δC,
ppm: 18.05 (3-Me), 25.60 (CH2Br), 66.93 (C6), 87.51
(C5), 127.26 (C1′), 128.78 (C2′), 130.35 (C3′), 134.55
(C4′), 138.60 (C3), 140.27 (C2), 163.85 (C1), 178.74
(NC=O), 183.51 (C4). Found, %: Br 62.24, 62.69.
C15H10Br5NO2. Calculated, %: Br 62.84.
4-Nitro-N-(5,5,6-tribromo-3-isopropyl-6-methyl-
4-oxocyclohex-2-en-1-ylidene)benzamide (XXIIc).
1H NMR spectrum, δ, ppm: 1.03–1.12 d.d (6H,
3-CHMe2, J = 6.6 Hz), 2.12 s (3H, 6-Me), 2.96–3.10 m
(1H, 3-CH), 6.59 s (1H, 2-H), 8.08–8.30 d.d (4H,
C6H4, J = 8.7 Hz).
4,6-Dibromo-3,6-dimethyl-2,5-dioxocyclohex-3-
en-1-yl benzoate (XXIX). Yield 42%, mp 134–136°C.
1H NMR spectrum, δ, ppm: 2.00 s (3H, 3-Me), 2.29 s
(3H, 6-Me), 6.07 s (1H, 1-H), 7.45–8.00 m (5H, Ph).
13C NMR spectrum, δC, ppm: 17.98 (3-Me), 24.03
(6-Me), 58.09 (C6), 78.73 (C1), 128.00 (C1′), 128.73
(C2′), 130.05 (C3′), 134.14 (C4′), 137.44 (C4), 149.07
(C3), 164.15 (OC=O), 183.66 (C5), 186.35 (C2). Found,
%: Br 38.01, 38.23. C15H12Br2O4. Calculated, %:
Br 38.41.
N-(3,5,6-Tribromo-2,5-dimethyl-4-oxocyclohex-
2-en-1-ylidene)benzamide (XXIVa). Yield 80%,
1
mp 122–124°C. H NMR spectrum, δ, ppm: 2.06 s
(3H, 5-Me), 2.53 s (3H, 2-Me), 5.10 s (1H, 6-H), 7.48–
7.98 m (5H, Ph). 13C NMR spectrum, δC, ppm: 19.98
(2-Me), 25.62 (5-Me), 47.70 (C6), 56.40 (C5), 128.78
(C2′), 129.66 (C3′), 131.30 (C3), 131.57 (C1′), 134.34
(C4′), 145.69 (C2), 158.63 (C1), 179.13 (NC=O), 182.64
(C4). Found, %: Br 50.05, 50.29. C15H12Br3NO2. Cal-
culated, %: Br 50.15.
4,6-Dibromo-6-isopropyl-3-methyl-2,5-dioxocy-
1
clohex-3-en-1-yl benzoate (XXX). H NMR spec-
trum, δ, ppm: 1.48 d (6H, 6-CHMe2, J = 7.2 Hz),
2.27 s (3H, 3-Me), 2.36–2.50 m (1H, 6-CH), 6.17 s
(1H, 1-H), 7.41–8.03 m (5H, Ph).
4-Nitro-N-(3,5,6-tribromo-2,5-dimethyl-4-oxo-
cyclohex-2-en-1-ylidene)benzamide (XXIVc). Yield
1
N-(5-Bromo-4-hydroxy-2,3-dimethylphenyl)-
benzamide (XXXIVa). Yield 89%, mp 209–210°C.
Found, %: Br 24.74, 24.92. C15H14BrNO2. Calculated,
%: Br 24.96.
54%, mp 179–180°C. H NMR spectrum, δ, ppm:
2.08 s (3H, 5-Me), 2.54 s (3H, 2-Me), 5.11 s (1H,
6-H), 8.14–8.37 d.d (4H, C6H4, J = 9.0 Hz). Found,
%: Br 45.59, 45.93. C15H11Br3N2O4. Calculated, %:
Br 45.84.
N-(5-Bromo-4-hydroxy-2,3-dimethylphenyl)-4-
methylbenzamide (XXXIVb). Yield 94%, mp 225.5–
228°C. Found, %: Br 23.75, 27.98. C16H16BrNO2. Cal-
culated, %: Br 23.91.
N-(3,5,6-Tribromo-2-isopropyl-5-methyl-4-oxo-
cyclohex-2-en-1-ylidene)benzamide (XXVIIa). Yield
1
26%, mp 122–124°C. H NMR spectrum, δ, ppm:
1.45–1.53 d.d (6H, 2-CHMe2, J = 7.2 Hz), 2.03 s (3H,
5-Me), 3.61–3.75 m (1H, 2-CH), 5.00 s (1H, 6-H),
7.48–7.98 m (5H, Ph). Found, %: Br 47.01, 47.32.
C17H16Br3NO2. Calculated, %: Br 47.37.
N-(5-Bromo-2,3-dimethyl-4-oxocyclohexa-2,5-
dien-1-ylidene)benzamide (XXXVIa). Yield 73%,
mp 140–142°C. H NMR spectrum, δ, ppm: 2.17 d
(3H, 3-Me, J = 1.2 Hz), 2.30 d (3H, 2-Me, J = 1.2 Hz),
7.32 (1H, 6-H), 7.48–7.90 m (5H, Ph). Found, %:
Br 25.07, 25.36. C15H12BrNO2. Calculated, %:
Br 25.11.
1
4-Nitro-N-(3,5,6-tribromo-2-isopropyl-5-methyl-
4-oxocyclohex-2-en-1-ylidene)benzamide (XXVIIc).
1
Yield 45%, mp 187–189°C. H NMR spectrum, δ,
ppm: 1.45–1.54 d.d (6H, 2-CHMe2, J = 7.2 Hz), 2.05 s
(3H, 5-Me), 3.64–3.78 m (1H, 2-CH), 5.01 s (1H,
6-H), 8.14–8.38 d.d (4H, C6H4, J = 9.3 Hz). 13C NMR
spectrum, δC, ppm: 18.76 and 20.16 (CHMe2), 25.48
(5-Me), 35.56 (CHMe2), 49.24 (C6), 56.45 (C5),
123.99 (C2′), 130.68 (C3′), 131.59 (C1′), 136.42
(C3), 151.00 (C2), 154.43 (C4′), 158.85 (C1), 175.62
(NC=O), 181.91 (C4). Found, %: Br 43.06, 43.46.
C17H15Br3N2O4. Calculated, %: Br 43.50.
N-(5-Bromo-2,3-dimethyl-4-oxocyclohexa-2,5-di-
en-1-ylidene)-4-methylbenzamide (XXXVIb). Yield
15%, mp 151.5–153°C. H NMR spectrum, δ, ppm:
2.17 d (3H, 3-Me, J = 0.9 Hz), 2.29 d (3H, 2-Me, J =
0.9 Hz), 2.44 s (3H, 4-MeC6H4), 7.31 s (1H, 6-H),
7.28–7.79 d.d (4H, C6H4, J = 8.4 Hz). Found, %:
Br 24.02, 24.16. C16H14BrNO2. Calculated, %:
Br 24.05.
1
N-(5,5,6,6-Tetrabromo-2,3-dimethyl-4-oxocyclo-
hex-2-en-1-ylidene)benzamide (XXXVIIIa). 1H NMR
spectrum, δ, ppm: 1.89 s (3H, 3-Me), 2.21 s (3H,
2-Me), 7.42–7.84 m (5H, Ph).
N-(2,5,5,6-Tribromo-6-bromomethyl-3-methyl-4-
oxocyclohex-2-en-1-ylidene)benzamide (XXVIII).
1
Yield 30%, mp 134–136°C. H NMR spectrum, δ,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 12 2009

HALOGENATION OF N-SUBSTITUTED p-QUINONE MONOIMINES ... X.
1813
3-Bromo-4-methyl-N-(5,5,6,6-tetrabromo-2,3-
XXXIa, and XXXIb and aminophenols IVa–IVc, Va–
Vc, VIa–VIc, XXXIIa, and XXXIIb.
dimethyl-4-oxocyclohex-2-en-1-ylidene)benzamide
1
(XXXVIIIc). H NMR spectrum, δ, ppm: 1.88 s (3H,
Quinone imines I–III, XVI–XXI, XXXIa, XXXIb,
XXXVa, XXXVb, XXXVIa, and XXXVIb were also
synthesized by oxidation of aminophenols IV–VI, X–
XV, and XXXII–XXXIV with lead tetraacetate in
acetic acid according to the procedure described in
[11] and were recrystallized from acetic acid.
3-Me), 2.20 s (3H, 2-Me), 2.48 s (3H, 4-MeC6H3),
7.34 d (1H, 5′-H, J = 9.6 Hz), 7.92–7.95 d.d (1H, 6′-H,
J = 9.6 Hz), 8.27 d (1H, 2′-H, J = 1.8 Hz).
N-(2,3,5,6-Tetrabromo-5,6-dimethyl-4-oxocyclo-
1
hex-2-en-1-ylidene)benzamide (XXXIX). H NMR
spectrum, δ, ppm: 1.34 s (3H, 5-Me), 1.73 s (3H,
6-Me), 7.40–7.88 m (5H, Ph).
REFERENCES
Hydrochlorination of quinone imines Ia–Ic, IIa–
IIc, IIIa–IIIc, XVIa–XVIc, XVIIIa–XVIIIc, XXa–
XXc, XXXIa, and XXXIb. A stream of dry gaseous
hydrogen chloride was passed over a period of 15–
20 min through a solution of the corresponding qui-
none imine in 5 ml of anhydrous chloroform. The solu-
tion became lighter, and a colorless solid separated.
The precipitate was filtered off, washed with acetic
acid, and recrystallized from acetic acid. Amino-
phenols Xa–Xc, XIIa–XIIc, XIVa–XIVc, XXXIIIa,
and XXXIIIb thus obtained were identical to the
corresponding chlorination products of quinone imines
Ia–Ic, IIa–IIc, IIIa–IIIc, XXXIa, and XXXIb and
aminophenols IVa–IVc, Va–Vc, VIa–VIc, XXXIIa,
and XXXIIb.
1. Avdeenko, A.P., Konovalova, S.A., Ludchenko, O.N.,
Shishkin, O.V., Palamarchuk, G.V., and Zubatyuk, R.I.,
Russ. J. Org. Chem., 2009, vol. 45, p. 1651.
2. Avdeenko, A.P. and Konovalova, S.A., Russ. J. Org.
Chem., 2006, vol. 42, p. 669.
3. Avdeenko, A.P., Pirozhenko, V.V., Shishkin, O.V.,
Shishkina, S.V., Konovalova, S.A., and Ludchen-
ko, O.N., Russ. J. Org. Chem., 2008, vol. 44, p. 542.
4. Avdeenko, A.P., Pirozhenko, V.V., Shishkin, O.V., Pala-
marchuk, G.V., Zubatyuk, R.I., Konovalova, S.A., and
Ludchenko, O.N., Russ. J. Org. Chem., 2008, vol. 44,
p. 807.
5. Burmistrov, K.S. and Burmistrov, S.I., Zh. Org. Khim.,
1980, vol. 16, p. 1487.
6. Avdeenko, A.P. and Velichko, N.V., Russ. J. Org.
Chem., 1995, vol. 31, p. 221.
Hydrobromination of quinone imines Ia–Ic, IIa–
IIc, IIIa–IIIc, XVIIa–XVIIc, XIXa–XIXc, XXIa–
XXIc, XXXIa, and XXXIb. The corresponding qui-
none imine, 0.01 mol, was dissolved in 10 ml of acetic
acid, and 2 ml of 46% hydrobromic acid was added.
The mixture became lighter. It was diluted with water,
and a colorless solid separated. The precipitate was
filtered off, washed with acetic acid, and recrystallized
from acetic acid. Aminophenols XIa–XIc, XIIIa–
XIIIc, XVa–XVc, XXXIVa, and XXXIVb thus ob-
tained were identical to the corresponding bromination
products of quinone imines Ia–Ic, IIa–IIc, IIIa–IIIc,
7. Burmistrov, K.S. and Yurchenko, A.G., Zh. Org. Khim.,
1990, vol. 26, p. 1995.
8. Avdeenko, A.P., Velichko, N.V., Romanenko, E.A., and
Pirozhenko, V.V., Zh. Org. Khim., 1991, vol. 27,
p. 2350.
9. Kostyanovsky, R.G., Avdeenko, A.P., Konovalova, S.A.,
Kadorkina, G.K., and Prosyanik, A.V., Mendeleev Com-
mun., 2000, no. 1, p. 16.
10. Avdeenko, A.P., Burmistrov, K.S., Dubina, V.L., and
Skripets, V.I., Ukr. Khim. Zh., 1980, vol. 46, p. 1081.
11. Adams, R. and Looker, J.H., J. Am. Chem. Soc., 1951,
vol. 73, p. 1145.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 12 2009