Quinone imines and aminophenols as precursors of new heterocycles

Article abstract of DOI:10.1007/s11172-006-0157-7

Cyclization of substituted quinone imines and diazabutadiene derivatives of aminophenols affords 4aH-phenoxazine or 4H-1,4-benzoxazine derivatives, which are finally transformed into the following fused heterocycles: the stable 1,4,6,8-tetra(tert-butyl)phenoxazin-10-yl radical and 7a, 14a, 15a, 15b-tetrahydro-14,16-dioxa-5,9-diaza-8,15-ethenohexaphene and 5a,6,11a,12-tetrahydro[1,4]benzoxazino[3,2-b][1,4]benzoxazine derivatives. The influence of the substituents on the pathways of the reactions of intermediate benzoxazines and phenoxazines, such as oxidation, [2+4] dimerization, and the closure of the second ring, was studied. The structures of the fused heterocycles were determined by X-ray diffraction, NMR spectroscopy, and ESR.

Full text of DOI:10.1007/s11172-006-0157-7

Russian Chemical Bulletin, International Edition, Vol. 54, No. 11, pp. 2571—2577, November, 2005
2571
Quinone imines and aminophenols as precursors of new heterocycles
G. A. Abakumov, N. O. Druzhkov, Yu. A. Kurskii,ꢀ L. G. Abakumova, A. S. Shavyrin, G. K. Fukin,
A. I. Poddel´skii, V. K. Cherkasov, and L. S. Okhlopkova
G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences,
49 ul. Tropinina, 603950 Nizhny Novgorod, Russian Federation.
Fax: +7 (831 2) 62 7497. Eꢀmail: kursk@iomc.ras.ru
Cyclization of substituted quinone imines and diazabutadiene derivatives of aminophenols
affords 4aHꢀphenoxazine or 4Hꢀ1,4ꢀbenzoxazine derivatives, which are finally transformed
into the following fused heterocycles: the stable 1,4,6,8ꢀtetra(tertꢀbutyl)phenoxazinꢀ10ꢀyl
radical and 7a,14a,15a,15bꢀtetrahydroꢀ14,16ꢀdioxaꢀ5,9ꢀdiazaꢀ8,15ꢀethenohexaphene and
5a,6,11a,12ꢀtetrahydro[1,4]benzoxazino[3,2ꢀb][1,4]benzoxazine derivatives. The influence of
the substituents on the pathways of the reactions of intermediate benzoxazines and phenꢀ
oxazines, such as oxidation, [2+4] dimerization, and the closure of the second ring, was
studied. The structures of the fused heterocycles were determined by Xꢀray diffraction, NMR
spectroscopy, and ESR.
Key words: cyclization, 4Hꢀ1,4ꢀbenzoxazine, 4aHꢀphenoxazine, 14,16ꢀdioxaꢀ5,9ꢀdiazaꢀ
8,15ꢀethenohexaphene, [1,4]benzoxazino[3,2ꢀb][1,4]benzoxazine, stable radical, Xꢀray difꢀ
fraction, NMR, ESR.
The range of heterocyclic compounds is being graduꢀ
ally extended due to the involvement of new synthons
capable of undergoing cyclization.1 The recently deꢀ
scribed2 cyclization of Nꢀarylꢀоꢀquinoneimines affords
chiral 4aHꢀphenoxazine derivatives (1). In molecule 1,
the 2Hꢀ1,4ꢀoxazine fragꢀ
ment, in which the double
bond is located at the niꢀ
trogen atom, is indicated by
hypothesized that the reaction affords substituted 1,4ꢀdiꢀ
azabutadiene as an intermediate, in which the intramoꢀ
lecular addition of two hydroxy groups at the C=N double
bonds occur. All the aboveꢀmentioned reactions give (or
supposedly give) heterocycles containing the 2Hꢀ1,4ꢀoxꢀ
azine fragment as intermediate products. The aim of the
present study was to examine the influence of the subꢀ
stituents on the pathways of the reactions of heterocycles
containing this isomeric oxazine fragment.
thick solid lines. This comꢀ
pound is an isomer of
4Hꢀ1,4ꢀoxazine containing
a substituent at the nitroꢀ
Oxidation of MnIII complex (2) containing two
Nꢀ(2,6ꢀdiisopropylphenyl)ꢀ3,5ꢀdi(tertꢀbutyl)ꢀоꢀbenzoꢀ
quinone imine ligands in air afforded 1,3,11,13ꢀtetra(tertꢀ
butyl)ꢀ6,8,14a,15bꢀtetraisopropylꢀ7a,14a,15a,15bꢀtetraꢀ
hydroꢀ14,16ꢀdioxaꢀ5,9ꢀdiazaꢀ8,15ꢀethenohexaphene (3)
(Scheme 1).
Analogous products were prepared by heating Nꢀarylꢀ
оꢀquinoneimines in solution as a result of cyclization givꢀ
ing rise to substituted 4aHꢀphenoxazines 1 followed by
Diels—Alder dimerization of 1.2 The dimerization occurs
stereoselectively to give only 7aR,8R,14aR,15S,15aS,15bR
isomer 3 and its 7aS,8S,14aS,15R,15aR,15bS enantiomer,
although the formation of eight diastereomers (a total of
16 isomers) is theoretically possible for cyclic compound
3 containing six chiral carbon atoms. Slow crystallization
of compound 3 prepared from complex 2 gave crystals
suitable for Xꢀray diffraction study. The structure of 3
was established by Xꢀray diffraction (Fig. 1). In comꢀ
pound 3, two 4,6ꢀdi(tertꢀbutyl)phenyloxyimine fragments
are linked by the 1,4ꢀethenoꢀ1,3,5,7ꢀtetraisopropylꢀ
1,2,3,4,4a,5,6,7aꢀoctahydronaphthalene fragments, and
gen atom. New isomers of phenoxazine appeared to be
highly reactive. In 1,4aꢀdialkylꢀ4aHꢀphenoxazines 1, the
double bonds at positions 1 and 3 are activated by the
2Hꢀ1,4ꢀoxazine fragment. Hence, compounds 1 readily
undergo Diels—Alder dimerization (thermal [2+4] dimerꢀ
ization), and the formation of 6,8ꢀdi(tertꢀbutyl)ꢀ1,4aꢀ
diisopropylꢀ4aHꢀphenoxazine was detected only in soluꢀ
tion by NMR spectroscopy.2 Condensation of оꢀaminoꢀ
phenols with ninhydrin affords stable 5aꢀhydroxyꢀ5aHꢀ
indeno[2,1ꢀb]benzoꢀ1,4ꢀoxazinꢀ5ꢀone derivatives3 (in the
fragment of 1, R = OH). The 4aꢀunsubstituted 4aHꢀphenꢀ
oxazine derivatives, which are apparently generated as
intermediates, are readily subjected to oxidation4 or oxiꢀ
dative aromatization.5 The reaction of 2ꢀpropynꢀ1ꢀol
with an excess of оꢀaminophenols or 2ꢀamino alcohol in
the presence of HgCl2 produces only cisꢀ[1,4]oxaziꢀ
no[3,2ꢀb][1,4]oxazine derivatives.6 In the study,6 it was
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2491—2496, November, 2005.
1066ꢀ5285/05/5411ꢀ2571 © 2005 Springer Science+Business Media, Inc.

2572
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005
Abakumov et al.
But
Pri
C(13)
C(12)
But
C(1)
O(14)
C(11)
C(10)
C(2)
But
C(14a)
C(15)
But
C(13a)
C(17)
O(16)
C(15a)
C(16a)
C(3)
C(4)
C(9a)
N(9)
C(18)
C(8a)
C(8)
C(4a)
N(5)
C(15b)
Pri
Pri
C(7a)
C(5a)
C(6)
C(7)
Pri
Fig. 1. Molecular structure of 3. The terminal carbon atoms of the tertꢀbutyl and isopropyl groups are omitted. Here and in Figs 2
and 4, the atoms are represented by anisotropic displacement ellipsoids at the 30% probability level.
Scheme 1
was observed also for other compounds containing the
1,4ꢀethenooctahydronaphthalene fragment.8
Heating of Nꢀ[2,5ꢀdi(tertꢀbutyl)phenyl]ꢀ3,5ꢀ(diꢀtertꢀ
butyl)ꢀоꢀbenzoquinone imine (4) also leads to intramoꢀ
lecular cyclization. This reaction is most probable for the
Z isomer. The barrier to the interconversion between the
E and Z isomers relative to the C=N bond is low (102 15
kJ mol–1).9 Unlike 4aꢀalkylꢀsubstituted phenoxazines,2
intermediate 4aHꢀphenoxazine is easily oxidized. In this
reaction, both atmospheric oxygen and the starting
quinone imine can serve as an oxidizer, the latter being
reduced to aminophenol. Diels—Alder dimerization of
this 4aHꢀphenoxazine derivative is hindered, because both
conjugated double bonds at positions 1 and 3 are shielded
by the bulky tertꢀbutyl groups. Oxidation affords the stable
radical, viz., 1,4,6,8ꢀtetra(tertꢀbutyl)phenoxazinꢀ10ꢀyl (5)
(Scheme 2). The structure of 5 was established by Xꢀray
diffraction (Fig. 2) and ESR spectroscopy (Fig. 3).
Xꢀray diffraction study demonstrated that molecule 5
is planar, and the Mе groups of the tertꢀbutyl substituents
are in an eclipsed configuration relative to each other.
The N(10)—C(9a) and N(10)—C(10a) distances are
1.364(4) and 1.369(4) Å, respectively. The N—C disꢀ
tances in radical 5 are somewhat shorter than those in
analogous phenoxazines (for example, 1.375—1.425 Å in
10ꢀ(3´ꢀchlorobutyl)phenoxazine10 and 1.397—1.411 Å in
10ꢀ(3´ꢀchloropropyl)ꢀ2ꢀchlorophenoxazine11) and are
longer than the analogous distances in pyridine (1.337 Å).7
This is a consequence of delocalization the unpaired elecꢀ
tron over the C(9a)—N(10)—C(10a) fragment.
the molecule, as a whole, adopts a Z configuration. The
lengths of the single bonds (except for C(7a)—C(8)) and
double bonds in the 1,4ꢀethenooctahydronaphthalene
fragment are in the ranges typical of the C—C and C=C
bonds (1.447(2)—1.563(2) and 1.328(2)—1.337(2) Å, reꢀ
spectively) and agree with the tabulated values.7 The
C(7a)—C(8) distance is 1.603(2) Å, which is, apparently,
attributed to steric hindrance caused by the isopropyl
group at position 8. The C(17)...C(14a), C(17)...C(15a),
C(18)...C(8a), and C(18)...C(7a) distances are in the
range of 2.454(2)—2.512(2) Å. An analogous situation
This radical is highly stable. For example, it remains
intact in solutions of concentrated strong organic and
mineral acids and captures a proton to form the radical
cation of 1,4,6,8ꢀtetra(tertꢀbutyl)ꢀ10Hꢀphenoxazine. The

Quinoneimines as precursors of heterocycles
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005 2573
Scheme 2
In the presence of acids, N,N´ꢀbis(hydroxyphenyl)ꢀ
substituted diazabutadienes (7a,b) easily undergo rearꢀ
rangements. An attempt to synthesize dimethylꢀsubstiꢀ
tuted (R = Me) diazadiene 7b failed. The product is unꢀ
stable and was rearranged to give 2,4,8,10ꢀtetra(tertꢀbuꢀ
tyl)ꢀ5a,11aꢀdimethylꢀ5a,6,11a,12ꢀtetrahydro[1,4]benzꢀ
O(5)
C(6)
C(4)
C(1)
C(5a)
C(4a)
C(3)
C(7)
C(8)
oxazino[3,2ꢀb][1,4]benzoxazine (8b) already during the
synthesis (Scheme 3).
Apparently, the formation of the heterocycle started
with protonation of the nitrogen atom. The positive charge
in the cation is localized not on the nitrogen atom but
predominantly on the adjacent carbon atom. The subseꢀ
quent nucleophilic intramolecular cyclization affords
2Hꢀ1,4ꢀbenzoxazine, in which the oxazine ring includes
the chiral carbon atom.
C(2)
C(9a)
C(10a)
C(9)
N(10)
The replacement of the hydrogen atoms of the azadiene
fragment in 7a with the methyl substituents increases staꢀ
bility of the cation. As a result, the rearrangement of
dimethylꢀsubstituted diazadiene 7b occurs more easily.
The direction of the approach of the oxygen atom to the
carbon atom in the course of second cyclization is conꢀ
trolled by the configuration of the first chiral center. That
is why only a racemic mixture of the RR and SS isomers is
produced.
Fig. 2. Molecular structure of stable radical 5.
a
Xꢀray diffraction study of tetracyclic compound 8b
(Fig. 4) demonstrated that the methyl substituents
b
H(12)
N(12)
C(10)
C(1)
C(9)
C(8)
O(11)
C(11a)
C(6a)
C(10a)
C(12a)
C(4a)
C(2)
C(3)
C(5a)
O(5)
N(5)
C(7)
1 mT
H(5)
C(4)
Fig. 3. Experimental (a) and calculated (b) ESR spectra of stable
radical 5.
structure of radical 5 was chemically confirmed by the
fact that it is reduced with hydrazine hydrate to give
1,4,6,8ꢀtetra(tertꢀbutyl)ꢀ10Hꢀphenoxazine (6).
Fig. 4. Molecular structure of 8b. The structure of one indepenꢀ
dent molecule is shown; only the H atoms at the N atoms are
displayed.

2574
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005
Abakumov et al.
Scheme 3
R = H (a), Me (b)
50 MHz for 13C) with Me4Si as the internal standard. The data
were processed using the XwinNMR 2.1 program. The ESR
spectra were measured on a Bruker ER200DꢀSRC instrument
operating at 9.5 GHz. The IR spectra were recorded on a
Perkin—Elmer 577 instrument in Nujol mulls. Xꢀray diffraction
data sets for complexes 3 and 8b were collected on an automated
Smart APEX diffractometer. Xꢀray diffraction data for comꢀ
plex 5 were measured on a Siemens P3/PC diffractometer. The
principal crystallographic characteristics, details of Xꢀray data
collection, and parameters of structure refinement are given in
Table 1. All structures were solved by direct methods and refined
are in cis positions with respect to each other. The
Me—C(5a)—C(11a)—Me dihedral angle is 62°. The conꢀ
figuration and geometry of product 8b are similar to the
corresponding characteristics of (5aR,11aR)ꢀ5a,6,11a,12ꢀ
tetrahydroꢀ5aꢀmethylꢀ11aꢀphenylꢀ[1,4]benzoxaziꢀ
no[3,2ꢀb][1,4]benzoxazine.6
The NMR spectroscopic data confirm that the cis isoꢀ
mer containing the chiral C(5a) and C(11a) centers in the
RR or SS configuration is formed both in the case of 8a
and 8b. The 13C NMR spectra of products 8a and 8b each
show six peaks corresponding to the carbon atoms of two
aromatic rings, one signal for the C(5a) and C(11a) atoms,
and signals for two nonequivalent tertꢀbutyl groups. Adꢀ
ditional signals, which could belong to the trans isomers
of 8a or 8b containing chiral centers in the RS configuraꢀ
tion, were not observed.
To summarize, оꢀquinone imines and оꢀaminophenols
are convenient starting compounds serving as precursors
of new heterocycles. Cyclization of substituted оꢀquinone
imines or diazadiene derivatives of оꢀaminophenols affords
unstable intermediate 4aHꢀphenoxazine or 4Hꢀ1,4ꢀbenzꢀ
oxazine derivatives. Then unsubstituted 4aHꢀphenoxazine
derivatives are easily oxidized, 4aꢀalkylꢀsubstituted
4aHꢀphenoxazine derivatives spontaneously undergo
Diels—Alder dimerization, and Nꢀоꢀaminophenol derivaꢀ
tives of 4Hꢀ1,4ꢀbenzoxazine close the second heterocycle.
The reactions proceed stereoselectively to give fused
heterocycles in high yields.
by the leastꢀsquares method against F 2 with anisotropic disꢀ
hkl
placement parameters for all nonhydrogen atoms. The H atoms
in complexes 3 and 5 were located from difference Fourier maps
and refined isotropically. The H atoms in complex 8b were
placed in geometrically calculated positions and refined using a
riding model. All calculations were carried out with the use of
the SHELXTL v. 6.10 program package.12 Absorption correcꢀ
tions were applied using the SADABS program.13
[4,6ꢀDi(tertꢀbutyl)ꢀNꢀ(2,6ꢀdiisopropylphenyl)ꢀоꢀiminobenzoꢀ
semiquinono]ꢀ[4,6ꢀdi(tertꢀbutyl)ꢀNꢀ(2,6ꢀdiisopropylphenyl)ꢀ
оꢀamidophenolato]manganese(III) tetrahydrofuranate (2) was preꢀ
pared according to a known procedure.14
1,3,11,13ꢀTetra(tertꢀbutyl)ꢀ6,8,14a,15bꢀtetraisopropylꢀ
7a,14a,15a,15bꢀtetrahydroꢀ14,16ꢀdioxaꢀ5,9ꢀdiazaꢀ8,15ꢀethenoꢀ
hexaphene (3). Compound 2 (0.225 mmol, 0.2 g) was dissolved
in toluene (30 mL) and the mixture was refluxed in air for
30 min. After recrystallization at –12 °C for 2 days, dark semiꢀ
transparent rhombic crystals of 3 with m.p. 152—154 °C (with
decomp.) were obtained in a yield of 0.05 g (29.2%). The Xꢀray
diffraction data are given in Tables 1 and 2. The structure is
completely identical to that established earlier by twoꢀdimenꢀ
sional NMR.2
Experimental
2,4ꢀDi(tertꢀbutyl)ꢀ6ꢀ[2´,5´ꢀdi(tertꢀbutyl)phenyl]iminocycloꢀ
hexaꢀ2,4ꢀdienꢀ1ꢀone (4). 3,5ꢀDi(tertꢀbutyl)ꢀоꢀbenzoquinone
(10 mmol, 2.2 g) was dissolved in methanol (20 mL), and
2,5ꢀdi(tertꢀbutyl)aniline (2.05 mL) was added. The reaction
Oneꢀ and twoꢀdimensional NMR spectra were recorded on
a Bruker Avance DPXꢀ200 instrument (200 MHz for 1H and

Quinoneimines as precursors of heterocycles
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005 2575
Table 1. Principal crystallographic characteristics, details of Xꢀray diffraction study, and parameters of
structure refinement for 3, 5, and 8b
Parameter
Formula
Molecular weight
Temperature/K
3
5
8b
C52H74N2O2
C28H40NO
759.13
100(2)
P21/c
C32H48N2O2
406.61
492.73
293(2)
293(2)
P21/n
Space group P21/n
a/Å
b/Å
c/Å
β/deg
V/Å3
Z
21.5738(9)
20.792(4)
10.602(2)
11.342(2)
98.74(3)
2471.0(9)
4
1.093
0.065
56
15.5889(7)
10.5861(5)
36.9007(17)
94.774(1)
6068.4(5)
4
9.9610(4)
22.2183(10)
109.663(1)
4496.2(3)
8
ρ
calc/g cm–3 1.121
1.079
0.066
50
µ/mm–1
2θmax/deg
0.067
58
Number of measured reflections
Number of reflections with I > 2σ
Number of parameters in refinement
R1 (I > 2σ(I ))
46263
2770
33008
10300 (Rint = 0.0286) 1505 (Rint = 0.1023) 10686 (Rint = 0.0438)
789
431
0.0569
0.1163
721
0.0713
0.0568
0.1468
wR2 (based on F 2 for all reflections)
Weighting scheme
0.1978
2
2
2
w
–1 = σ (F02) + (αP)2 + βP, where P = 1/3(F0 + 2Fc
)
α
β
0.0765
1.8421
0.0494
0.1254
0.0895
1.8676
Residual electron density
peaks, max/min, e Å–3
Transmission factors, Tmin/Tmax
1.520/–0.216
0.112/–0.173
0.487/–0.230
0.9734/0.9934
0.9489/0.9969
mixture was stirred without heating for 10 h (until the color of
the starting quinone disappeared). The precipitate that formed
was filtered off and dissolved in diethyl ether. After recrystallizaꢀ
tion from diethyl ether, darkꢀbrown crystals of 4 precipitated.
The product with m.p. 121—123 °C was isolated in a yield of
1.9 g (49.6%). Found (%): C, 82.35; H, 10.29. C28H41NO. Calꢀ
culated (%): C, 82.50; H, 10.14. IR (Nujol mulls), ν/cm–1: 1670
(C=O); 1630 (C=N). 1H NMR (CDCl3), δ: 1.12, 1.27, 1.34,
and 1.35 (all s, 9 H each, But); 6.25 (d, 1 H, C(5)H, J = 2.4 Hz);
6.42 (d, 1 H, C(6´)H, J = 2.2 Hz); 7.04 (d, 1 H, C(3)H, J =
2.4 Hz); 7.15 (dd, 1 H, C(4´)H, J = 2.2 and 8.2 Hz); 7.34 (d,
1 H, C(3´)H, J = 8.2 Hz).
1,4,6,8ꢀTetra(tertꢀbutyl)phenoxazinꢀ10ꢀyl (5). Formic acid
(1—2 drops) was added to a solution of 4 (10 mmol, 4.07 g) in
methanol (70 mL), and the reaction mixture was heated for 2 h.
The precipitate that formed was filtered off and dissolved in
hexane. After recrystallization from hexane, brightꢀred crystals
of 5 precipitated. The product with m.p. 158—160 оC was isoꢀ
lated in a yield of 3.2 g (78.9%). Found (%): C, 82.79; H, 10.09.
C28H40NO. Calculated (%): C, 82.76; H, 9.92. ESR (a/mT):
1,4,6,8ꢀTetra(tertꢀbutyl)ꢀ10Hꢀphenoxazine (6). A solution
of hydrazine hydrate was added dropwise to a suspension of 5
(10 mmol, 4.06 g) in methanol (50 mL) under argon until the
precipitate was completely dissolved and the reaction mixture
turned colorless. After cooling, colorless crystals of 6 precipiꢀ
tated. The product was isolated in a yield of 2.76 g (64.2%).
Found (%): C, 82.45; H, 9.87. C28H41NO. Calculated (%):
C, 82.50; H, 10.14. IR (Nujol mulls), ν/cm–1: 1205 (C—O—C),
3600 (NH). 1H NMR (CDCl3), δ: 1.26, 1.40, 1.43, and 1.46
(all s, 9 H each, But); 5.32 (s, 1 H, NH); 6.25 (d, 1 H, C(7)H,
J = 2.5 Hz); 6.63 (d, 1 H, C(3)H, J = 8.6 Hz); 6.72 (d, 1 H,
C(9)H, J = 2.5 Hz); 6.74 (d, 1H, C(2), J = 8.6 Hz). 13C NMR
(CDCl3): 30.2, 30.7, 30.9, and 31.3 (C(CH3)3); 33.5, 34.33,
34.4, and 34.8 (C(CH3)3); 109.0 (C(9)H); 116.5 (C(C(7)H);
118.1 (C(3)H); 120.2 (C(2)H); 130.3, 130.6, 131.0, 135.0, 136.3,
140.0, 143.4 (C(1), C(4), C(4a), C(5a), C(6), C(9a), C(10a));
145.4 (C(8)).
N,N´ꢀEthaneꢀ1,2ꢀdiylidenedi(2ꢀaminoꢀ4,6ꢀdiꢀtertꢀbutylꢀ
phenol) (7a). A 40% glyoxal solution (0.23 mL, 2 mmol) in
methanol (5 mL) was added with stirring to a solution of
2ꢀaminoꢀ4,6ꢀdi(tertꢀbutyl)phenol (4 mmol, 0.89 g) in methanol
(25 mL). After 1 h, yellow crystals of 7a that precipitated were
filtered off and washed with cold methanol. The product was
isolated in a yield of 0.52 g (55%). Found (%): C, 77.27; H, 9.69.
C30H44N2O2. Calculated (%): C, 77.59; H, 9.48. IR (Nujol
mulls), ν/cm–1: 3360 (OH); 1625 (C=N). 1H NMR (CDCl3), δ:
1.34 and 1.45 (both s, 18 H each, But); 7.27 (d, 2 H, C(5)H, J =
2.3 Hz); 7.35 (d, 2 H, C(3)H, J = 2.3 Hz); 7.85 (br.s, 2 H, OH);
8.6 (s, 2 H, CH=N). 13C NMR (CDCl3), δ: 29.3, 31.5
(C(CH3)3); 34.6, 35.1 (C(CH3)3); 109.8 (C(3)H); 125.9
g
=
2.0037, aN
=
=
0.747, aH(1 H, C(2)H)
0.406, aH(1 H, C(7)H)
=
=
0.076,
0.406,
aH(1 H, C(3)H)
aH(1 H, C(9)H) = 0.283. The Xꢀray diffraction data are given in
Tables 1 and 2. After dissolution of 5 in a mixture of triꢀ
fluoroacetic and sulfuric acid, the radical cation was obtained.
ESR of the protonated form (a/mT): g = 2.0035, aN = 0.720,
aH(1 H, C(2)H)
= 0.055 aH(1 H, C(3)H) = 0.330,
aH(1 H, C(7)H) = 0.330, aH(1 H, C(9)H) = 0.125, aH(1 H,
NH) = 0.84. The theoretical spectrum was calculated using the
WinEPR Simfonia v.1.25 program.

2576
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005
Abakumov et al.
Table 2. Selected bond lengths (d) and bond angles (ω) in compounds 3, 5, and 8b
Parameter
Value
Parameter
Value
Parameter
Value
Compound 3
Bond
d/Å
Bond
d/Å
Angle
ω/deg
N(5)—C(4a)
N(5)—C(5a)
C(5a)—C(6)
C(6)—C(7)
C(7)—C(7a)
C(7a)—C(8)
C(8)—C(8a)
N(9)—C(8a)
N(9)—C(9a)
1.412(2)
1.282(2)
1.477(2)
1.337(2)
1.501(2)
1.603(2)
1.531(2)
1.278(2)
1.418(2)
C(14a)—C(15)
C(14a)—C(8a)
C(15)—C(15a)
C(15a)—C(15b)
C(15a)—C(7a)
C(15b)—C(5a)
C(15)—C(17)
C(17)—C(18)
C(18)—C(8)
1.549(2)
1.523(2)
1.558(2)
1.547(2)
1.563(2)
1.518(2)
1.503(2)
1.328(2)
1.518(2)
C(17)—C(15)—C(14a)
C(17)—C(15)—C(15a)
C(14a)—C(15)—C(15a)
C(18)—C(8)—C(7a)
C(8a)—C(8)—C(7a)
C(18)—C(8)—C(8a)
107.0(1)
109.6(1)
107.23(9)
104.3(1)
100.37(9)
110.9(1)
Compound 5
Bond
d/Å
Bond
d/Å
Angle
ω/deg
O(5)—C(5a)
O(5)—C(4a)
N(10)—C(9a)
1.402(4)
1.400(4)
1.364(4)
N(10)—C(10a)
C(5a)—C(9a)
C(4a)—C(10a)
1.369(4)
1.399(5)
1.416(5)
C(4a)—O(5)—C(5a)
C(9a)—N(10)—C(10a)
119.7(3)
118.9(3)
Compound 8b*
Bond
d/Å
Angle
ω/deg
Angle
ω/deg
O(5)—C(4a)
O(5)—C(5a)
O(11)—C(10a) 1.382(2)/1.384(2)
O(11)—C(11a) 1.444(2)/1.448(2)
C(5a)—C(11a) 1.534(3)/1.539(3)
N(6)—C(5a)
N(6)—C(6a)
N(12)—C(11a) 1.424(3)/1.424(2)
N(12)—C(12a) 1.406(2)/1.416(2)
1.379(2)/1.387(2)
1.451(2)/1.444(2)
C(4a)—O(5)—C(5a)
117.0(1)/117.0(1)
O(5)—C(5a)—C(11a) 107.6(2)/107.8(1)
C(21)—C(5a)—C(11a) 114.2(2)/114.2(2)
N(12)—C(11a)—O(11) 107.6(2)/107.8(1)
N(12)—C(11a)—C(30) 109.9(2)/110.1(2)
O(11)—C(11a)—C(30) 108.5(2)/109.2(2)
N(12)—C(11a)—C(5a) 108.3(2)/108.0(2)
C(30)—C(11a)—C(5a) 114.5(2)/114.0(2)
C(10a)—O(11)—C(11a) 117.5(1)/117.3(1)
C(6a)—N(6)—C(5a) 117.2(2)/118.0(2)
C(12a)—N(12)—C(11a) 117.4(2)/116.9(1)
N(6)—C(5a)—O(5)
N(6)—C(5a)—C(21)
O(5)—C(5a)—C(21)
N(6)—C(5a)—C(11a)
107.6(2)/107.3(1)
110.4(2)/110.2(2)
108.6(2)/109.3(2)
108.1(2)/107.8(2)
1.422(2)/1.427(2)
1.413(2)/1.408(2)
* The geometric characteristics for the second independent molecule are also given.
(C(5)H); 133.4 and 136.0 (C(6), C(2)); 147.7 (CH=N); 150.1
and 150.4 (C(4), C(1)).
in a yield of 0.69 g (65%). Found (%): C, 77.91; H, 9.59.
C32H48N2O2. Calculated (%): C, 78.05; H, 9.76. IR (Nujol
1
2,4,8,10ꢀTetra(tertꢀbutyl)ꢀ5a,6,11a,12ꢀtetrahydro[1,4]benzꢀ
oxazino[3,2ꢀb][1,4]benzoxazine (8a). Compound 7a (1 mmol,
0.47 g) was dissolved in methanol (30 mL) and two drops of
formic acid were added. The reaction mixture was refluxed
for 2 h. Then methanol was removed, and the reaction mixture
was dissolved in hexane, from which colorless crystals of 8a
precipitated upon cooling. The product was isolated in a yield of
0.35 g (75%). Found (%): C, 77.18; H, 9.30. C30H44N2O2. Calꢀ
culated (%): C, 77.59; H, 9.48. IR (Nujol mulls), ν/cm–1: 3440,
3390 (NH). 1H NMR (CDCl3), δ: 1.28 and 1.33 (s, 9 H each,
But); 4.70 (br.d, 2 H, NH, J = 3.8 Hz); 5.23 (s, 2 H, CH—N);
6.57 (d, 2 H, C(3)H and C(9)H, J = 2.3 Hz); 6.77 (d, 2 H,
C(1)H and C(7)H, J = 2.3 Hz). 13C NMR (CDCl3), δ: 29.9,
31.6 (C(CH3)3); 34.4, 34.9 (C(CH3)3); 76.3 (CH—NH); 110.1
(C(1)H and C(7)H); 114.7 (C(3)H and C(9)H); 128.9, 137.6,
138.0, 143.6 (C(2) and C(8), C(6a) and C(12a), C(4a) and
C(10a), C(4) and C(10)).
2,4,8,10ꢀTetra(tertꢀbutyl)ꢀ5a,11aꢀdimethylꢀ5a,6,11a,12ꢀ
tetrahydro[1,4]benzoxazino[3,2ꢀb][1,4]benzoxazine (8b). Diꢀ
acetyl (2 mmol) and formic acid (2 drops) were added to a
solution of 2ꢀaminoꢀ4,6ꢀdi(tertꢀbutyl)phenol (4 mmol, 0.89 g)
in methanol (30 mL). The reaction mixture was heated and
refluxed for 2 h. Then methanol was removed, and the reaction
mixture was dissolved in isooctane, from which colorless crysꢀ
tals of 8b precipitated upon cooling. The product was isolated
mulls), ν/cm–1: 3420 (OH), 3400 (NH). H NMR (CDCl3), δ:
1.19 and 1.26 (both s, 9 H each, But); 1.56 (s, 6 H, Me); 4.2
(br.s, 2 H, NH); 6.54 (d, 2 H, C(1)H, C(7)H, J = 2.4 Hz); 6.71
(d, 2 H, C(3)H, C(9)H, J = 2.4 Hz). 13C NMR (CDCl3), δ: 22.5
(Me); 29.8, 31.8 (C(CH3)3); 34.4, 34.9 (C(CH3)3); 82.5 (C(5a),
C(11a)); 110.5 (C(1)H, C(7)H); 115.0 (C(3)H, C(9)H); 128.6,
136.6, 138.9, 142.4 (C(2) and C(8), C(4) and C(10), C(4a) and
C(10a), C(6a) and C(12a)). The Xꢀray diffraction data are given
in Tables 1 and 2. There are two molecules per asymmetric unit
cell. The independent molecules have similar geometric paꢀ
rameters.
This study was financially supported by the Russian
Foundation for Basic Research (Project Nos 04ꢀ03ꢀ32409
and 04ꢀ03ꢀ32413) and the Council on Grants of the Presiꢀ
dent of the Russian Federation (Program for State Supꢀ
port of Leading Scientific Schools of the Russian Federaꢀ
tion, Grant NShꢀ1649.2003.3).
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Received February 4, 2005;
in revised form September 12, 2005