NMR study of products of thermal transformation of substituted N-aryl-o-quinoneimines

Article abstract of DOI:10.1023/A:1023979311368

Products of thermal transformation of substituted N-aryl-o-quinoneimines were studied using NMR spectroscopy. The formation of 4aH-phenoxazine, which was further dimerized by the Diels-Alder reaction, was established.

Full text of DOI:10.1023/A:1023979311368

712
Russian Chemical Bulletin, International Edition, Vol. 52, No. 3, pp. 712—717, March, 2003
NMR study of products of thermal transformation
of substituted Nꢀarylꢀoꢀquinoneimines*
ꢀ
G. A. Abakumov, N. O. Druzhkov, Yu. A. Kurskii, and A. S. Shavyrin
G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences,
49 ul. Tropinina, 603600 Nizhny Novgorod, Russian Federation.
Fax: +7 (831 2) 66 1497. Eꢀmail: andrew@imoc.sinn.ru
Products of thermal transformation of substituted Nꢀarylꢀoꢀquinoneimines were studied
using NMR spectroscopy. The formation of 4aHꢀphenoxazine, which was further dimerized by
the Diels—Alder reaction, was established.
Key words: substituted Nꢀarylꢀoꢀquinoneimines, hexaphene, 4aHꢀphenoxazine, NMR,
2D NMR, structure.
Arylꢀsubstituted оꢀbenzoquinoneimines are quinone
ucts were isolated upon heating of individual compounds
derivatives bearing several reaction centers capable of enꢀ
tering into various chemical reactions.1 The area of their
application covers chelating systems, dyes, and starting
compounds for syntheses of metalꢀcoordinating ligands.
The purpose of our work is to study the products
formed both on heating of individual Nꢀ(2,6ꢀdialkylꢀ
phenyl)ꢀ3,5ꢀdiꢀtertꢀbutylꢀоꢀbenzoquinoneimines 1 and
during the synthesis of these compounds.
1a and 1b. It was found that heating of 1a,b in heptane for
12 h resulted in decoloration of the solution. Since the
initial compounds 1а and 1b are intensely dark red, we
can suggest their complete transformation. Compounds
1a,b are not completely consumed in methanol under the
same conditions.
It is known that quinoneimines with the aryl substituꢀ
ent at the nitrogen atom can form cyclic products1,2 due
to the electrocyclic reaction of ring closure.3 For example,
the oxidation of 2ꢀaminoꢀ4,6ꢀdiꢀtertꢀbutylphenol with
3,5ꢀdiꢀtertꢀbutylbenzoquinone affords 2,4,6,8ꢀtetraꢀtertꢀ
butylꢀ1Нꢀphenoxazinꢀ1ꢀone in high yields and quinoneꢀ
imine as an intermediate.2 It should be mentioned that
compounds 1 can exhibit Z/Eꢀisomerism similar to that
observed for other quinoneimines.4,5 Ring closure is posꢀ
sible only for the Zꢀisomer relatively to the C=N bond.
Probably, this rearrangement can be initiated by the
Z/Eꢀtransition via the torsion twisting mechanism.4 The
aromatic and quinoneimine rings are situated in different
planes, and rotation of the rings relatively to each other is
sterically hindered. Due to this, the NMR spectra exhibit
the nonequivalent methyl groups of the isopropyl subꢀ
stituents in compound 1b.
Prevalence of ring closure reactions for the quinoneꢀ
imine systems suggests the formation of the cyclic prodꢀ
uct of the phenoxazine type at the first step of thermal
transformation of compound 1. The Zꢀisomer of 1 should
produce 4aHꢀphenoxazine derivative 2 when the aromatic
ring turns to the same plane with the quinoneimine ring.
Molecule 2 has a chiral center in position 4а, i.e., a mixꢀ
ture of Rꢀ and Sꢀenantiomers forms. This phenoxazine
isomer has not previously been prepared, and its formaꢀ
tion was assumed only as an intermediate.3 We succeeded
to detect the formation of compound 2b by NMR on
R = Me (a), Pri (b)
The synthesis of 1 from 3,5ꢀdiꢀtertꢀbutylꢀоꢀbenzoꢀ
quinone and 2,6ꢀdisubstituted anilines affords, along with
the main product, a new compound being, probably, a
dimer, because the total number of protons and nonꢀ
equivalent carbon atoms in the NMR spectra doubles
compared to that expected for compound 1. The resulting
compound has a distinct melting point. According to the
IR spectroscopic data, it contains no carbonyl groups and
is asymmetric, because the most part of protons and alꢀ
most all carbon atoms, except for those of the methyl
groups in the tertꢀbutyl substituents, are nonequivalent in
the NMR spectra. The methyl groups in the isopropyl
substituents are also nonequivalent, indicating the presꢀ
ence of chiral centers or steric hindrance. Similar prodꢀ
* Dedicated to Academician I. P. Beletskaya on the occasion of
her anniversary.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 682—687, March, 2003.
1066ꢀ5285/03/5203ꢀ712 $25.00 © 2003 Plenum Publishing Corporation

Thermal transformation of Nꢀarylꢀoꢀquinoneimines Russ.Chem.Bull., Int.Ed., Vol. 52, No. 3, March, 2003
713
heating in methanolꢀd4. The presence of the ABM system
of protons in the diene region, AB system in the aromatic
region, and signals from the tertꢀbutyl groups in the
1Н NMR spectrum of intermediate 2b proves the strucꢀ
ture of 2b. The individual compound was not isolated,
because the product was unstable and readily entered into
subsequent transformations.
Considering possible routes for the preparation of the
dimer, we concluded that dimerization by the Diels—Alder
reaction was most probable. An attempt to grow crystals
R = Me (a), Pri (b)
appropriate for Xꢀray diffraction analysis was unsuccessꢀ
ful. The modern twoꢀdimensional NMR methods make it
possible to obtain (in the liquid phase) data, whose inforꢀ
mative content is comparable with that of Xꢀray diffracꢀ
tion analysis.6 The structure of the product was deterꢀ
mined using the oneꢀ and twoꢀdimensional procedures6,7
Table 1. Correlations in the 2D NMR spectra of compound 3a
Atom, group
Crossꢀpeaks
COSY
COLOC
NOESY
C(1)
C(1)C(CH3)3
C(3), C(11)
C(1)—C(CH3)3
C(1)—C(CH3)3
C(3)—C(CH3)3,
C(11)—C(CH3)3
C(3)—C(CH3)3,
C(11)—C(CH3)3
С(5a)
C(3)C(CH3)3, C(11)—C(CH3)3
C(1)C(CH3)3
C(1)C(CH3)3
C(3)C(CH3)3,
C(11)—C(CH3)3
C(3)C(CH3)3,
C(11)—C(CH3)3
C(6)CH3, C(15b)CH3, С(7)H
C(6)CH3
Harom
Harom
w
w
С(15)H, Harom
Harom
С(6)
C(6)CH3
С(7)H
С(7a)H, С(7)H, C(6), C(15a)H
C(6)CH3
С(7)H w, С(7a)H w
C(6)CH3 w, С(7a)H w,
С(15a)H
С(7)H
C(8)CH3, C(6)CH3,
С(7a)H
С(7a)H
C(6)CH3 w, С(15a)H,
С(7)H
C(8)CH3, C(15b)CH3,
C(6)CH3, С(15a)H, С(7)H
С(8)
C(8)CH3
C(8)CH3
С(8a)
C(8), C(8a)
С(15)H w, C(8)CH3,
С(18)H w
С(18)H, С(7)H
C(14a)CH3
w
C(13)
C(13)C(CH3)3
C(13)C(CH3)3
C(13)C(CH3)3
C(14a)CH3
C(13)—C(CH3)3
C(13)—C(CH3)3
С(14a)
Harom
w
C(14a)CH3, Harom
C(14a)CH3
C(14a), C(15)H, C(8a)
С(15)H w, С(17)H w
С(15)H, С(15a)H,
C(13)—C(CH3)3
С(15)H
C(14a)CH3
C(15b)CH3
C(14a)CH3 w, С(15a)H,
С(18)H, С(17)H
C(14a)CH3, С(15a)H,
С(18)H w, С(17)H,
C(1)C(CH3)3
C(15b)CH3, С(7a)H,
С(15)H, C(1)C(CH3)3,
С(15a)H
С(7a)H, С(15)H,
С(7)H w, С(17)H w,
C(15b)CH3 w
C(14a)CH3
w
С(15b)
C(15b)CH3
C(15b)CH3
С(17)H
C(15b), C(15a)H
C(15b)CH3
С(15a)H
С(15)H, С(18)H,
C(14a)CH3
C(8)CH3, С(15)H w,
С(17)H
C(14a)CH3 w, C(8)CH3,
С(15)H, С(18)H, С(15a)H w
С(15)H, С(17)H, C(8)CH3 w
С(18)H
Harom
Carom
Harom, C(CH3)3
Harom, C(CH3)3
Harom, C(CH3)3 w
Harom, C(CH3)3

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Abakumov et al.
Table 2. Correlations in the 2D NMR spectra of compound 3b
Atom, group
Crossꢀpeaks
COLOC
COSY
NOESY
C(1)
С(1)C(CH3)3
C(1) w
С(1)C(CH3)3
w
w
С(1)C(CH3)3
С(1)C(CH3)3
C(3),C(11)
Harom, C(15a)H w
С(3)C(CH3)3 w,
С(11)C(CH3)3
С(3)C(CH3)3,
С(11)C(CH3)3
w
w
w
С(3)C(CH3)3,
С(11)C(CH3)3
С(3)C(CH3)3,
С(11)C(CH3)3
С(4а)
C(3) w, C(11) w
Harom
С(6)CH(CH3)2
C(7)H
w
C(5a)
C(6)
C(6)CH(CH3)2
С(6)CH(CH3)2
C(6), C(4a)H w
C(6), C(4a)H w
C(5a)
w
w
С(6)CH(CH3)2
С(6)CH(CH3)2
С(6)CH(CH3)2
С(7)H
С(6)CH(CH3)2
С(6)CH(CH3)2
С(6)CH(CH3)2
C(7a)H
C(7)H, С(6)CH(CH3)2
С(6)CH(CH3)2
C(7)H, С(6)CH(CH3)2
C(8)CH(CH3)2, C(7a)H,
C(6)CH(CH3)2
С(7а)H
C(15a)H
C(7)H
C(7)H, C(8)CH(CH3)2 w
C(8)
C(8)CH(CH3)2
C(8)CH(CH3)2
C(8)CH(CH3)2
C(8)CH(CH3)2
C(8) w
w
w
C(8)CH(CH3)2
C(8)CH(CH3)2
C(8)CH(CH3)2
C(8)CH(CH3)2, C(7)H,
C(7a)H w, C(18)H w
C(8)CH(CH3)2, C(7)H,
C(7a)H w, C(18)H w
C(8)CH(CH3)2
C(8) w
C(8)CH(CH3)2
C(8a)
C(15)H w
C(13)
С(13)C(CH3)3
C(13) w
С(13)C(CH3)3
С(14a)CH(CH3)2
С(14а)CH(CH3)2
C(14a) w
w
С(13)C(CH3)3
С(13)C(CH3)3
C(14a)
С(14а)CH(CH3)2
С(14a)CH(CH3)2
С(14a)CH(CH3)2
С(15)H
Harom, С(15)H w
w
w
С(14а)CH(CH3)2
С(14а)CH(CH3)2
С(14а)CH(CH3)2
C(15a)H, C(18)H,
C(17)H
С(14a)CH(CH3)2
С(14a)CH(CH3)2
С(13)C(CH3)3, C(18)H w,
C(17)H
C(14a) w
C(8a)
С(15a)H
C(7a)H
C(7a)H, C(15)H
С(15b)CH(CH3)2, С(7а)Н,
С(1)C(CH3)3
C(15b)
С(15b)CH(CH3)2
С(15b)CH(CH3)2
C(15b) w
C(15b) w
C(18)H
w
С(15b)CH(CH3)2
С(15b)CH(CH3)2
С(15b)CH(CH3)2
С(17)H
С(15b)CH(CH3)2
С(15b)CH(CH3)2
С(15b)CH(CH3)2
C(18)H, C(15)H
C(17)H, C(15)H
С(15b)CH(CH3)2
С(15b)CH(CH3)2
С(15b)CH(CH3)2, C(15a)H
C(15)H, C(18)H
C(17)H, C(15)H w,
C(8)CH(CH3)2 w
all C(CH3)3
С(18)H
C(17)H
Harom
Carom
Harom, C(CH3)3
Harom, C(CH3)3
of 1Н and 13С NMR, DEPT, COSY, NOESY, XHCORR
(carbonꢀproton correlation), and COLOC (carbonꢀproꢀ
ton longꢀrange correlation) (Tables 1 and 2). These proꢀ
cedures allow one to observe hyperfine interactions, inꢀ
cluding those invisible in the 1D 1Н and 13C NMR spectra.
We succeeded to establish that the thermal transformaꢀ
tion of compounds 1a and 1b produced products 3a and
3b, respectively.
Let us consider how NMR data can be applied for
revealing the structure of the product using the С(15)Н
group and its nearest environment. It is impossible to
determine the position of the signal belonging to С(15)Н
1
using the H NMR spectra only. Based on the chemical
1
shifts and multiplicities of the Н NMR signals, we find
the pair of adjacent protons at the double bond of С(17)Н
and С(18)Н at 6.26 and 5.77 ppm. It is seen from the

Thermal transformation of Nꢀarylꢀoꢀquinoneimines Russ.Chem.Bull., Int.Ed., Vol. 52, No. 3, March, 2003
715
COSY spectrum that this pair is characterized by the scaꢀ
lar spinꢀspin coupling, and the proton at 6.26 ppm has the
scalar coupling with the protons at 1.11, 1.68, and
3.64 ppm. The signals at 1.11 and 1.68 ppm (C(14a)CH3
and C(8)CH3) belong to protons of the methyl groups
(1Н NMR, DEPT). Therefore, the signal at 3.64 ppm
belongs to С(15)Н, which is confirmed by the 13С NMR,
XHCORR, and DEPT data. This proton is characterized
by spinꢀspin couplings (in the COSY spectrum) with the
methyl group at δ 1.11 and with the protons at δ 3.31,
6.26, and 5.77 (С(15a)H, С(17)Н, and С(18)Н, respecꢀ
tively). The twoꢀdimensional NOESY spectrum maniꢀ
fests the interaction of С(15)Н with the protons at δ 1.11,
3.31, and 5.77 (С(14а)СН3, С(15а)Н, and С(17)Н, reꢀ
spectively), indicating their close arrangement in the
space. The COLOC spectrum exhibits the longꢀrange spinꢀ
spin 13С—Н coupling of С(15) with С(14a)СН3.
All observed interactions coincide with those
expected for the С(15)Н fragment in structure 3а.
The data of the COSY and NOESY spectra make
it possible to monitor the chain of correlations
C(7)H—C(7a)H—C(15a)H—C(15)H—C(17)H—С(18)H
and others characteristic of structures 3а and 3b. The
XHCORR and COLOC spectra allowed us to assign
all lines in the 13C NMR spectra and confirmed the
connectivities revealed in the homonuclear correlation
experiments. Thus, based on the data of the oneꢀ and
twoꢀdimensional spectra, we obtained a consistent patꢀ
tern for interactions in the molecule. This pattern was
expected for the proposed structure. All lines observed in
the proton and carbon spectra were assigned to the fragꢀ
ments of the structure.
The fine analysis of the NOESY spectrum and threeꢀ
dimensional model of the molecule allowed the relative
configuration of all six chiral centers of 3а to be deterꢀ
mined. For example, a weak intensity of the crossꢀ
peaks of C(15a)H and С(7a)H with the protons of the
C(17)H=C(18)H bridge in the NOESY spectrum of 3а
suggests that the distance between these pairs of protons is
greater than 4Å.6 According to the threeꢀdimensional
model of the molecule optimized in the HyperChem proꢀ
gram, this is possible only if the C(15a)H and С(7a)H
protons are in the endoꢀposition relatively to the bridge
in the
ring
and, vice versa, the methyl protons of C(14a)CH3
are arranged in the exoꢀposition relatively to the
C(17)H=C(18)H bridge, because the NOESY spectrum
contains crossꢀpeaks between the protons of the
C(14a)CH3 and C(17)H groups. The methyl group
of the C(15b)CH3 fragment is situated at one side
of the
ring
with the protons at the C(7a) and C(15a) atoms, because
the NOESY spectrum exhibits the dipoleꢀdipole interacꢀ
tion between the protons of the C(15b)CH3, C(15a)H,
and C(7a)H fragments. The resulting configuration corꢀ
responds to the exoꢀproduct of the Diels—Alder reaction,
and the reacting molecules during the reaction should fit
each other as it is shown below.
Note that four isomers of the carbon framework could
be generated by the dimerization reaction due to the inꢀ
volvement of different double bonds in the reaction. Each
isomer could have several diastereomers due to different
relative orientations of the molecules during the interacꢀ
tion. In the case of several isomers or several diastereꢀ
omers in the reaction product, we would observe an inꢀ
This variant of the approach is more sterically favorꢀ
able because the substituents in position 4а of the reacting
molecules are directed to opposite sides relatively to the
plane in which the diene rings localized. The reaction
involves R+Rꢀ or S+Sꢀ2. The predominant formation of
the exoꢀproduct can be explained by the fact that this
provides better conditions during the reaction for the
dienophile πꢀorbitals, which are not involved in the reacꢀ
tion, to overlap. The [2+4]ꢀcycloaddition reaction inꢀ
volves the πꢀС(6)—С(7) bonds of one molecule and
С(6)—С(7) and С(8)—С(9) bonds of another molecule.
The С(8)—С(9) bond does not act as a dienophile, probꢀ
ably, due to steric hindrance.
1
crease in the number of the Н and 13С NMR spectral
lines, which could not be assigned to one molecule beꢀ
cause necessary 2Dꢀcorrelation crossꢀpeaks would be abꢀ
sent from the spectra. In fact, the reaction produces preꢀ
dominantly one isomer with a certain relative configuraꢀ
tion of chiral centers, because we assigned all signals in
1
the Н and 13С NMR spectra using the twoꢀdimensional
procedures and found no signal of any additional isomers.
Therefore, only one certain double bond reacts as a
dienophile of two bonds present in molecule 2, and only
one variant is realized during [2+4]ꢀcycloaddition among
several variants of relative orientation of asymmetric molꢀ
ecules 2: one diastereomer and its enantiomer are formed.
Such a high stereoselectivity confirms that dimerization
occurs due to the Diels—Alder reaction.
Thus, the intermediate and final products of the therꢀ
mal transformation of Nꢀarylꢀоꢀbenzoquinoneimines 1 in
hexane and methanol were established. Based on the strucꢀ
tures of the intermediate and final products, we conꢀ

716
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 3, March, 2003
Abakumov et al.
6.0 Hz, J3,4 = 9.5 Hz); 7.27 (d, 1 Н, С(9)Н, J9,7 = 2.4 Hz); 7.30
(d, 1 Н, С(7)Н, J7,9 = 2.4 Hz).
Constants and refined chemical shifts of protons in the reꢀ
gion of 6.0—7.3 ppm were obtained by iteration fitting of the
simulated spectra of the AB and ABM systems.
cluded that the reaction mechanism should include the
ring closure of quinoneimine 1 to form 4аНꢀphenoxazine
2 followed by the dimerization of 2 through [2+4]ꢀcycloꢀ
addition to form compound 3. Product 3 forms with a
high stereospecificity.
1,3,11,13ꢀTetraꢀtertꢀbutylꢀ6,8,14а,15bꢀtetramethylꢀ
7а,14а,15а,15bꢀtetrahydroꢀ14,16ꢀdioxaꢀ5,9ꢀdiazaꢀ8,15ꢀethenoꢀ
hexaphene (3a). Quinoneimine 1а (3.2 g, 10 mmol) was disꢀ
solved in heptane (70 mL) in an evacuated system and heated on
a boiling water bath for 12 h until the solution became colorless.
Compound 3a was isolated from the reaction mixture at ∼20 °C
in 72% yield (2.3 g) as colorless crystals. Found (%): C, 81.20;
H, 9.00. C44H58N2O2. Calculated (%): C, 81.69; H, 9.04;
O, 4.95. IR (Nujol), ν/cm–1: 1645 (C=N); 1235 (C—O—C).
1Н NMR (CDCl3), δ: 1.10 (s, 3 Н, C(14a)CH3); 1.27 (s, 3 Н,
C(15b)CH3); 1.33 (s, 18 Н, C(3)C(CH3)3 and C(11)C(CH3)3);
1.44 (s, 9 Н, C(13)C(CH3)3); 1.47 (s, 9 Н, C(1)C(CH3)3); 1.68
(s, 3 Н, C(8)CH3); 2.00 (br.s, 3 Н, C(6)CH3); 2.80 (m, 1 Н,
С(7a)H); 3.34 (d, 1 Н, С(15a)H, J = 8.0 Hz); 3.64 (d, 1 Н,
С(15)H, J = 6.8 Hz); 5.77 (dd, 1 Н, С(18)H, J = 8.1 Hz, J =
1.1 Hz); 6.00 (m, 1 Н, С(7)H); 6.26 (dd, 1 Н, С(17)H, J =
6.8 Hz, J = 8.1 Hz); 7.18, 7.19, 7.22, 7.31 (all m, 1 Н each,
C(2)H, C(4)H, C(10)H, C(12)H). 13С NMR (CDCl3), δ:
16.9 (C(8)CH3); 18.1 (C(6)CH3); 18.3 (C(14a)CH3); 25.8
(C(15b)CH3); 30.0 (C(1)C(CH3)3); 30.3 (C(13)C(CH3)3);
31.56, 31.61 (C(3)C(CH3)3, C(11)C(CH3)3); 34.39, 34.46
(C(3)C(CH3)3, C(11)C(CH3)3); 35.0 (C(13)C(CH3)3); 35.2
C(1)C(CH3)3); 43.7 (С(15a)H); 44.3 (С(15)H); 48.0 (С(7a)H);
48.6 (С(8)); 73.8 (С(15b)); 74.3 (С(14a)); 121.5, 122.4, 123.0,
123.2 (C(2)H, C(4)H, C(10)H, C(12)H); 130.9 (С(17)H); 132.6
(С(7)H); 132.4 (С(6)); 135.0, 136.1, 141.5, 141.4 (C(4a), C(9a),
C(13a), C(16a)); 136.0 (С(18)H); 136.5 (C(1)); 137.4 (C(13));
143.3, 143.4 (C(3), C(11)); 161.1 (С(5a)); 170.5 (С(8a)).
1,3,11,13ꢀTetraꢀtertꢀbutylꢀ6,8,14а,15bꢀtetraisopropylꢀ
7а,14а,15а,15bꢀtetrahydroꢀ14,16ꢀdioxaꢀ5,9ꢀdiazaꢀ8,15ꢀethenoꢀ
hexaphene (3b) was synthesized similarly from quinoneimine 1a
(3.8 g, 10 mmol). Compound 3b was isolated in 65% yield (2.47 g)
as colorless crystals. Found (%): C, 82.31; H, 9.58. C52H74N2O2.
Calculated (%): C, 82.27; H, 9.83. IR (Nujol), ν/cm–1: 1645
(C=N); 1235 (C—O—C). 1Н NMR (CDCl3), δ: 0.69 (d,
3 H, С(14a)(CH3)CHCH3, J = 7.1 Hz); 0.75 (d, 3 H,
Experimental
Oneꢀdimensional and twoꢀdimensional NMR spectra were
obtained on a Bruker Avance DPXꢀ200 instrument (200 MHz
for 1H, 50 MHz for 13C). The following twoꢀdimensional exꢀ
periments were carried out: COSY, protonꢀproton correlation
due to spinꢀspin coupling (including COSY45 (shortꢀrange inꢀ
teractions) and COSY90 (longerꢀrange interactions)); NOESY,
protonꢀproton correlation due to the dipoleꢀdipole interaction;
XHCORR, carbonꢀproton correlation due to the spinꢀspin inꢀ
teraction between the adjacent nuclei; and COLOC, carbonꢀ
proton correlation due to the longꢀrange spinꢀspin interaction
between nuclei. Twoꢀdimensional COLOC experiments were
carried out with optimization for constants of 3 and 10 Hz. In
NOESY experiments, mixing time of 250 ms was used. IR specꢀ
tra were recorded on a Perkin Elmer 577 instrument.
3,5ꢀDiꢀtertꢀbutylquinone was synthesized using a known
procedure.8 2,6ꢀDimethylaniline was a commercial product
available from Fluka, and commercial 2,6ꢀdiisopropylaniline
(Aldrich) was used.
Nꢀ(2,6ꢀDimethylphenyl)ꢀ3,5ꢀdiꢀtertꢀbutylꢀоꢀbenzoquinoneꢀ
imine (1a). 3,5ꢀDiꢀtertꢀbutylquinone (2.2 g, 10 mmol) and
2,6ꢀdimethylaniline (1.5 mL, 12 mmol) were dissolved in MeOH
(20 mL), and 1—2 drops of 88% HCOOH were added. The
mixture was stirred using a magnetic stirrer at ∼20 °C for 6 h
until the starting quinone disappeared. Compound 1a was isoꢀ
lated from the reaction mixture in 82% yield (3.83 g) as dark
cherryꢀcolored crystals, m.p. 102—103 °C. Found (%): С, 82.22;
Н, 9.00. Calculated (%): С, 81.73; Н, 8.97. IR (Nujol, ν/cm–1):
1670 (С=О); 1630 (С=N). 1Н NMR (CDCl3), δ: 1.09, 1.34
(both s, 9 H each, But); 1.94 (s, 6 H, CH3); 5.84 (d, 1 H,
C=CH, J = 2.3 Hz); 6.90—7.00 (m, 3 H, PhH); 7.02 (d, 1 H,
C=CH, J = 2.3 Hz).
Nꢀ(2,6ꢀDiisopropylphenyl)ꢀ3,5ꢀdiꢀtertꢀbutylꢀоꢀbenzoquinoneꢀ
imine (1b). Compound 1b was synthesized similarly from 3,5ꢀdiꢀ
tertꢀbutylquinone (2.2 g, 10 mmol) and 2,6ꢀdiisopropylaniline
(1.8 mL, 11 mmol) in 68% yield (2.58 g) as dark red crystals,
m.p. 145—147 °C. Found (%): С, 83.00; Н, 10.24. Calcuꢀ
lated (%): С, 82.30; Н, 9.76. IR (Nujol), ν/cm–1: 1670 (С=О);
С(14a)(CH3)CHCH3,
С(15b)(CH3)CHCH3,
С(15b)(CH3)CHCH3,
С(6)(CH3)CHCH3,
С(6)(CH3)CHCH3,
J
J
J
=
=
=
7.1 Hz); 0.82 (d,
7.1 Hz); 0.94 (d,
7.1 Hz); 1.04 (d,
7.1 Hz); 1.11 (d,
7.1 Hz); 1.29 (d,
3
3
3
3
3
H,
H,
H,
H,
H,
J
J
=
=
C(8)(CH3)CHCH3, J = 7.1 Hz); 1.32, 1.33 (both s, 9 Н each,
С(3)C(CH3)3, С(11)C(CH3)3); 1.44 (s, 9 Н, С(1)C(CH3)3);
1.51 (s, 9 Н, С(13)C(CH3)3); 1.58 (d, 3 H, C(8)(CH3)CHCH3,
J = 7.1 Hz); 1.96 (m, 1 Н, С(15b)CH(CH3)2); 2.10 (m, 1 Н,
С(14а)CH(CH3)2); 2.11 (m, 1 Н, C(8)CH(CH3)2); 3.17 (m,
1 Н, С(7а)H); 3.22 (m, 1 Н, С(6)CH(CH3)2); 3.37 (d, 1 H,
С(15a)H, J = 7.8 Hz); 3.63 (d, 1 H, С(15)H, J = 6.8 Hz); 5.70
(d, 1 H, С(18)H, J = 8.0 Hz); 5.83 (d, 1 H, С(7)H, J = 3.6 Hz);
6.16 (dd, 1 H, С(17)H, J = 6.8 Hz, J = 8.0 Hz); 7.10, 7.13, 7.08,
7.13 (all m, 1 H each, C(2)H, C(4)H, C(10)H, C(12)H).
13С NMR (CDCl3), δ: 16.1 (С(15b)(CH3)CHCH3); 17.3
(С(15b)(CH3)CHCH3); 17.7 (C(8)(CH3)CHCH3); 18.35
(С(6)(CH3)CHCH3); 18.36 (C(8)(CH3)CHCH3); 19.9
(С(14a)(CH3)CHCH3); 22.1 (С(6)(CH3)CHCH3); 22.8
1
1635 (С=N). Н NMR: (CDCl3), δ: 1.10 (s, 9 H, But); 1.39 (s,
9 H, But); 1.08 (d, 6 H, 2 CH3CHCH3, J = 6.8 Hz); 1.18 (d,
6 H, 2 CH3CHCH3, J = 6.8 Hz); 2.68 (sept, 2 H, 2 CHMe2,
J = 6.8 Hz); 5.90 (d, 1 H, C=CH, J = 2.3 Hz); 7.04 (d, 1 H,
C=CH, J = 2.3 Hz); 7.16 (m, 3 H, PhH).
6,8ꢀDiꢀtertꢀbutylꢀ1,4аꢀdiisopropylꢀ4аНꢀphenoxazine (2b).
Quinoneimine 1b (3.2 g, 10 mmol) was dissolved in MeOH
(70 mL) in an evacuated system and heated on a boiling water
bath for 3 h. The formation of compound 2b in the resulting
mixture was detected by NMR. 1Н NMR (CD3OD), δ: 1.33,
1.45 (both s, 9 H each, But); 2.12 (br.sept, 1 H, С(1)CHMe2);
2.28 (sept, 1 H, C(4a)CHMe2); 6.11 (dd, 1 Н, С(4)Н, J4,2
1.3 Hz, J4,3 = 9.5 Hz); 6.29 (dt, 1 Н, С(2)Н, J2,3 = 6.0 Hz, J2,4
=
=
=
1.3 Hz, JH(2),C(1)CHMe = 1.4 Hz); 6.38 (dd, 1 H, C(3)H, J3,2
(С(14a)(CH3)CHCH3);
27.8
(С(6)CH(CH3)2);
30.2
2

Thermal transformation of Nꢀarylꢀoꢀquinoneimines Russ.Chem.Bull., Int.Ed., Vol. 52, No. 3, March, 2003
717
(С(1)C(CH3)3);
(С(14а)CH(CH3)2); 31.5, 31.6 (С(3)C(CH3)3, С(11)C(CH3)3);
32.4 (C(8)CH(CH3)2); 34.2, 34.3 (С(3)C(CH3)3,
30.6
(С(13)C(CH3)3);
31.3
2. E. P. Ivakhnenko, Doct. Sci. (Chem.) Thesis, Rostovꢀonꢀ
Don, 1991, p. 216 (in Russian).
3. S. RodriguesꢀMorgade, P. Vazquez, and T. Torres, Tetraꢀ
hedron, 1996, 52, 6781.
4. S. N. Lyubchenko, V. V. Litvinov, R. A. Ryskina, E. P.
Ivakhnenko, V. A. Kogan, and L. P. Olekhnovich, Zh. Obshch.
Khim., 1990, 60, 1618 [J. Gen. Chem. USSR, 1990, 60 (Engl.
Transl.)].
5. L. P. Olekhnovich, S. N. Lyubchenko, I. N. Shcherbakov,
S. V. Kurbatov, and V. A. Kogan, Ross. Khim. Zh. im. D. I.
Mendeleeva, 1996, 40, 139 [Mendeleev Chem. J., 1996, 40
(Engl. Transl.)].
С(11)C(CH3)3); 34.93 (С(13)C(CH3)3); 35.00 (С(1)C(CH3)3);
37.5 (С(15b)CH(CH3)2); 41.2 (С(15a)H); 41.5 (С(15)H); 45.6
(С(7а)H); 54.7 (C(8)); 80.3 (C(14a)); 81.0 (C(15b)); 121.6,
122.2, 123.7, 123.8, (C(2)H, C(4)H, C(10)H, C(12)H); 127.6
(С(7)H); 129.0 (С(17)H); 130.4 (C(6)); 133.9 (C(13)); 136.4
(C(1)); 139.0 (С(18)H); 142.0, 134.5, 143.2 (C(9a), C(13a),
C(16a)); 142.07, 142.7 (C(3), C(11)); 147.3 (С(4а)); 159.7
(C(5a)); 167.9 (C(8a)).
This work was financially supported by the Russian
Foundation for Basic Research (Project Nos. 00ꢀ15ꢀ97336
and 01ꢀ03ꢀ33065). Spectral works were carried out at the
Analytical Center of the Institute of Organometallic
Chemistry of the RAS (Russian Foundation for Basic
Research, Project No. 00ꢀ03ꢀ42004).
6. A. E. Derome, Modern NMR Techniques for Chemistry Reꢀ
search, Pergamon Press, Oxford, 1987.
7. S. Braun, H.ꢀO. Kalinowski, and S. Berger, 100 and More
NMR Experiments, Weinheim, VCH, 1996.
8. I. S. Belostotskaya, N. L. Komissarova, Z. V. Dzhuaryan, and
V. V. Ershov, Izv. Akad. Nauk SSSR, Ser. Khim., 1972, 1594
[Bull. Acad. Sci. USSR, Div. Chem. Sci., 1972, 21 (Engl.
Transl.)].
References
1. The Chemistry of Quinonoid Compounds, Eds. S. Patai and
Received May 17, 2002;
Z. Rappoport, John Wiley and Sons, 1988, 1712 pp.
in revised form October 2, 2002