The formation and thermal decomposition of 4-hydroperoxy-2-hydroxy-3,4,6- triisopropylcyclohexa-2,5-dienone

Article abstract of DOI:10.1023/A:1026029410312

Auto-oxidation of 3,4,6-triisopropylcatechol affords crystalline 2-hydroxy-4-hydroperoxy-3,4,6-triisopropylcyclohexa-2,5-dienone. Thermal decomposition of the resulting hydroperoxide was carried out and the reaction products were determined. The decomposition mainly proceeds by a route without cleavage of the O - O bond, unusual for hydroperoxides, to give the starting 3,4,6-triisopropylcatechol and 3,4,6-triisopropylbenzo-1,2-quinone. The hydroperoxide decomposes in part according to the traditional pattern involving the O - O bond cleavage to give 3-hydroxy-2,5-diisopropylbenzo-1,4-quinone.

Full text of DOI:10.1023/A:1026029410312

Russian Chemical Bulletin, International Edition, Vol. 52, No. 8, pp. 1847—1853, August, 2003
1847
The formation and thermal decomposition of 4ꢀhydroperoxyꢀ2ꢀhydroxyꢀ
3,4,6ꢀtriisopropylcyclohexaꢀ2,5ꢀdienone
ꢀ
G. A. Abakumov, N. N. Vavilina, Yu. A. Kurskii, V. I. Nevodchikov, V. K. Cherkasov, and A. S. Shavyrin
G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences,
49, ul. Tropinina, 603600 Nizhnii Novgorod, Russian Federation
Fax: +7 (831 2) 66 1497. Eꢀmail: andrew@imoc.sinn.ru
Autoꢀoxidation of 3,4,6ꢀtriisopropylcatechol affords crystalline 2ꢀhydroxyꢀ4ꢀhydroperoxyꢀ
3,4,6ꢀtriisopropylcyclohexaꢀ2,5ꢀdienone. Thermal decomposition of the resulting hydroperꢀ
oxide was carried out and the reaction products were determined. The decomposition mainly
proceeds by a route without cleavage of the O—O bond, unusual for hydroperoxides, to give the
starting 3,4,6ꢀtriisopropylcatechol and 3,4,6ꢀtriisopropylbenzoꢀ1,2ꢀquinone. The hydroperꢀ
oxide decomposes in part according to the traditional pattern involving the O—O bond cleavꢀ
age to give 3ꢀhydroxyꢀ2,5ꢀdiisopropylbenzoꢀ1,4ꢀquinone.
Key words: quinones, catechols, oxidation, hydroperoxide, hydroperoxycyclohexadienone,
thermal decomposition, NMR, 2D NMR procedures.
Catechols and quinones readily undergo redox reacꢀ
tions. Compounds of this type are used as oxidation inꢀ
hibitors and participate in many biological processes;
therefore, oxidation of these compounds with both oxyꢀ
gen1—4 and other oxidants,5 including those giving rise to
peroxides,1,6 has been studied rather comprehensively.
Spontaneous oxidation of 1,3,6,8ꢀtetraꢀtertꢀbutylꢀ4,5ꢀ
dihydroxyphenanthrene with oxygen in the light to give
1,3,6,8ꢀtetraꢀtertꢀbutylꢀ1ꢀhydroperoxyꢀ5ꢀhydroxyꢀ
4(1H )ꢀphenanthrenone is documented.1 Studies dealing
with the synthesis of substituted alkylperoxycyclohexaꢀ
dienones have been reported.6 Hydroperoxyhydroxyꢀ
cyclohexadienone has been suggested as an intermediate
in the oxidation of 3,6ꢀdiꢀtertꢀbutylbenzoꢀ1,2ꢀquinone
and 3,6ꢀdiꢀtertꢀbutylcatechol with tertꢀbutylhydroperꢀ
oxide.5 When investigating the oxidation of quinones and
catechols, some researchers5,6 assumed the involvement
of peroxycyclohexadienone radicals.
2ꢀhydroxyꢀ3,4,6ꢀtriisopropylcyclohexaꢀ2,5ꢀdienone (3).
The presence of the HOO group was confirmed by
Scheme 1
Autoꢀoxidation of catechol 1 by atmospheric oxygen
This study deals with the oxidation of 3,4,6ꢀtriisoꢀ
propylcatechol (1). This compound was prepared by alkyꢀ
lation of unsubstituted catechol with propanꢀ2ꢀol. Oxidaꢀ
tion of catechol 1 gave 3,4,6ꢀtriisopropylbenzoꢀ1,2ꢀ
quinone (2).
Upon slow crystallization of compound 1 from hexꢀ
ane, colorless needleꢀlike crystals were isolated. The
1H NMR spectrum of the product exhibited signals for
three isopropyl groups, two OH groups, and one ring
proton, as was to be expected for 1; however, all the methyl
groups of the isopropyl fragments were nonequivalent.
More detailed investigation using 1D (1H, 13C, DEPT 7)
and 2D (COSY, NOESY)7 NMR techniques allowed
identification of the isolated compound as 4ꢀhydroperoxyꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1751—1757, August, 2003.
1066ꢀ5285/03/5208ꢀ1847 $25.00 © 2003 Plenum Publishing Corporation

1848
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 8, August, 2003
Abakumov et al.
iodometric titration. It was further demonstrated that the
addition of compound 3 to a solution of 1 or keeping of a
solution of 1 in the light accelerates the formation of
hydroperoxide 3.
The transformation of catechol 1 into hydroperoxide 3
is apparently similar to autoꢀoxidation of some substiꢀ
tuted dihydroxyphenanthrenes1 (Scheme 1).
Crystalline hydroperoxide 3 is rather stable; it decomꢀ
poses on heating above the melting point (107—109 °C).
The COSY spectrum of compound 3 (Fig. 1) shows
spinꢀspin coupling of the methyl (δ 0.8—1.4) and methine
(δ 2.9—3.1) protons of the isopropyl groups and coupling
of the methine proton of one isopropyl group (δ 3.0) with
the ring proton C(5)H (δ 6.76). The observed nonꢀ
equivalence of the methyl groups in the isopropyl subꢀ
stituents is caused by the presence of a chiral center in the
molecule of 3; the largest difference between the chemiꢀ
cal shifts of the CH3 groups in the isopropyl substituent is
observed for C(4)Pri (∆δ 0.39), a smaller difference is
found for C(3)Pri (∆δ 0.09), and in the case of C(6)Pri,
which is fairly remote from the chiral center, this differꢀ
ence is negligible (∆δ 0.02).
of the methyl groups of the C(4)(CH3)CHCH3 fragment
(δ 1.10) are observed together with the trivial coupling of
the methine and methyl protons within each isopropyl
group. The C(5)H proton (δ 6.76) is coupled with the
protons of the two methyl groups in C(6)CH(CH3)2
(δ 1.12 and 1.14) and the methyl group in
C(4)(CH3)CHCH3 (δ 0.71). One can observe weak couꢀ
pling of the proton of the C(2)OH hydroxy group (δ 6.65)
with the methyl groups of C(3)CH(CH3)2 (δ 1.29, 1.38)
and peaks indicating the exchange between OH and OOH
groups with each other and with water protons.
According to Xꢀray diffraction data (Fig. 2, selected
bond lengths are given in the Experimental), the C—C
and C—O bond lengths are close to the average lengths for
such bonds in known compounds. In the crystal strucꢀ
ture, the molecules are connected by hydrogen bonds
(Fig. 3), two of these bonds being weak (the
O(2A)...O(1C), 2.7537(19) Å, and O(4B)...O(2C),
2.881(2) Å, distances are close to twice the van der Waals
radius of oxygen, 2.80 Å) and the third one being someꢀ
what stronger (O(1A)...O(2C) 2.6298(19) Å).
The data from 2D NMR spectra are consistent with
Xꢀray diffraction data and confirm the fact that the conꢀ
formations of compound 3 in solution and in the crystalꢀ
line state are similar.
In the NOESY spectrum of compound 3, the dipoleꢀ
dipole couplings of the protons of the C(3)CH(CH3)2
(δ 2.72) and C(4)CH(CH3)2 (δ 2.12) fragments and one
δ
1
2
3
4
5
6
7
7
6
5
4
3
2
1
δ
1
Fig. 1. Twoꢀdimensional H—1H (COSY) correlation spectrum of compound 3.

Hydroperoxycyclohexadienone
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 8, August, 2003
1849
The thermal decomposition of hydroperoxide 3 withꢀ
out a solvent (vacuum, 120 °C) is accompanied by gas
evolution. According to NMR data, the volatile prodꢀ
ucts isolated from the reaction mixture included water,
propanꢀ2ꢀol (major components), and a minor amount of
acetone. The presence of H2O2 (∼1—2%) in the volatile
products was established by iodometric titration.
C(12)
C(11)
C(10)
C(13)
O(2)
The major nonvolatile products formed in the decomꢀ
position of 3 include catechol 1 (∼35%), quinone 2
(∼20%), and 3ꢀhydroxyꢀ2,5ꢀdiisopropylbenzoꢀ1,4ꢀ
quinone (4) (∼25%). Attractive features are unusually high
yield of catechol 1 and the fact that the content of 1 in the
products is substantially higher than that of quinone 2.
The relative molar contents of identified compounds were
C(15)
C(14)
C(3)
O(3)
O(4)
H(40)
C(2)
C(1)
C(4)
1
determined from the integral intensities of the H NMR
C(5)
signals of the nonvolatile products formed upon decomꢀ
position of hydroperoxide 3. The resulting values coinꢀ
cided, to within the experimental error, with the yields
determined after chromatographic separation of the
products.
C(6)
O(1)
C(7)
C(9)
Thermal decomposition of hydroperoxide 3 follows
an unusual route with homolytic cleavage of the C—O
bond of the hydroperoxide group (Scheme 2).
C(8)
This decomposition route has been observed previꢀ
ously for related hydroperoxides with a cyclohexadiene
structure and bulky substituents in the ring.8 The radiꢀ
Fig. 2. Structure of hydroperoxide 3.
O(2A)
H(O(4C))
H(O(2))
O(1C)
O(2C)
O(4C)
O(3A)
O(3C)
O(4A)
O(1A)
H(O(4A))
H(O(2C))
H(O(4B))
O(4B)
O(1B)
H(O(2B))
O(2B)
O(3B)
Fig. 3. Fragment of the crystal structure of 3 (only the hydrogen atoms at the OH groups are shown). Molecules B and C are identical
and are enantiomers relative to molecule A.

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Russ.Chem.Bull., Int.Ed., Vol. 52, No. 8, August, 2003
Abakumov et al.
Scheme 2
Scheme 3
The major route of decomposition of hydroperoxide 3
The minor route of decomposition of hydroperoxide 3
frequency reaches 1010 s–1 at 120 °C. NMR analysis of the
decomposition products of 3 showed the presence of
isopropoxyphenols 5 and 6, which resulted from the secꢀ
ondary recombination reaction of the isopropyl and
phenoxyl radicals (1a,b) (Scheme 4).
Scheme 4
Recombination of radicals to give isopropoxyphenols
cal 1а produced upon the homolytic cleavage can be transꢀ
formed into the reaction products along two pathways,
namely, (i) by reduction to give catechol 1 and oxygen
and (ii) by disproportionation with the hydroperoxide radiꢀ
cal (a radical pair in the singlet (S) state) yielding diamagꢀ
netic products, quinone 2 and H2O2. Despite the fact that
only singlet radical pairs can recombine (disproportionꢀ
ate) to give diamagnetic products, the first disproportionꢀ
ation can also take place in the triplet (T) state of the
radical pair because the ground state of oxygen is a triplet.
Typical decomposition of hydroperoxide 3 accompaꢀ
nied by homolytic cleavage of the O—O bond yields radiꢀ
cal 3a, which is further converted into quinone 4 upon
fragmentation with elimination of an isopropyl radical
(Scheme 3). The share of this route is less than one third.
The use of CꢀphenylꢀNꢀtertꢀbutylnitrone as a spin trap
allowed detection of a stable radical resembling most
closely in its parameters9 (аH = 2.55 mT, аN = 14.75 mT,
g = 2.0062, dH = 1.2 mT) the spin adduct with the isoproꢀ
pyl radical.
The oxidation of quinones and catechols is known to
give reaction products with ring expansion.1,5 As shown
by NMR spectroscopy, the decomposition products of 3
contained minor amounts of 3,4,6ꢀtriisopropyloxepineꢀ
The two oxygen atoms in radical 1a are involved in
very fast proton exchange, similar to that in 3,6ꢀdiꢀtertꢀ
butylꢀ2ꢀhydroxyphenoxyl radical10 where the exchange

Hydroperoxycyclohexadienone
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 8, August, 2003
1851
The organic layer was separated, washed with a dilute solution
of NaOH and water, and dried with Na2SO4. After evaporation
of the solvent, the residue was recrystallized from hexane to give
26 g (65%) of compound 1, m.p. 75—77 °C. Found (%): C, 75.23;
H, 10.23. C15H24O2. Calculated (%): C, 75.46; H, 10.43.
IR (hexane), ν/cm–1: 3640, 3570 (OH free and intramolecular).
IR (Nujol), ν/cm–1: 3300 (OH intermolecular). 1H NMR
(CDCl3), δ: 1.21, 1.26 (both d, each 6 H, Me, J = 6.9 Hz); 1.39
(d, 6 H, Me, J = 7.1 Hz); 3.05, 3.17 (both sept, each 1 H,
CHMe2, J = 6.9 Hz); 3.37 (br.sept, 1 H, CHMe2, J = 7.1 Hz);
4.80, 5.37 (both br.s, each 1 H, OH); 6.65 (s, 1 H, C(5)H).
13C NMR (CDCl3), δ: 21.0, 22.7, 24.3 (Me); 26.8, 27.5, 29.2
(CHMe2); 113.5 (C(5)H); 128.9, 131.4, 138.6, 143.0 (C(1),
C(2), C(3), C(4), C(6)).
2,7ꢀdione (7) (less than 10% of the total product yield)
and 2ꢀhydroxyꢀ3,4,6ꢀtriisopropylbenzoꢀ1,4ꢀquinone (8)
(∼2—3%), which could be produced upon the secondary
oxidation of catechol 1 and quinone 2 with oxidants
present in the system.
3,4,6ꢀTriisopropylbenzoꢀ1,2ꢀquinone (2). A solution of
3,4,6ꢀtriisopropylcatechol (1) (10 mmol) in Et2O (100 mL) was
stirred for 2 h with an aqueous solution containing K3Fe(CN)6
(15.0 g), KOH (3 g), and Na2CO3 (5 g). The colorless solution
turned darkꢀred. After separation of the organic layer and evapoꢀ
ration of the solvent, the residue was recrystallized from hexane
to give 1.6 g (70%) of brownꢀred crystals of 2, m.p. 45—47 °C.
Found (%): C, 76.78; H, 9.58. C15H22O2. Calculated (%):
When the thermal decomposition of hydroperoxide 3
is carried out in a toluene solution at 110 °C, оꢀquinone 2
(∼40%) and pꢀquinone 4 (∼40%) are formed as the major
products, the fraction of catechol 1 being only 1—2% (the
1
yields were determined from the H NMR spectrum of
the resulting mixture). Due to its stability, radical 1a canꢀ
not abstract a hydrogen atom from the solvent (toluene)
molecule. In our opinion, radical 1a formed upon deꢀ
composition in a melt oxidizes predominantly the hydroꢀ
peroxide radical (see Scheme 2), being thus reduced to
catechol 1. However, in solution, the hydroperoxide radiꢀ
cal reacts with the solvent and is removed as H2O2. This
accounts for the smaller amount of catechol 1 and, as a
consequence, larger yields of quinones 2 and 4 as the
reaction products.
The ease of formation and specific features of decomꢀ
position of hydroperoxide 3 are probably due to the staꢀ
bility of radical 1а and its capability of being readily oxiꢀ
dized/reduced. At room temperature, radical 1а is oxiꢀ
dized with oxygen to hydroperoxide 3, whereas at 120 °C,
1а itself mainly oxidizes the •OOH radical to produce
oxygen, being thus reduced to catechol 1.
1
C, 76.88; H, 9.46. IR, ν/cm–1: 1665, 1685 (C=O). H NMR
(CDCl3), δ: 1.11, 1.18, 1.25 (all d, each 6 H, Me, J =
6.9 Hz); 2.93, 3.10, 3.22 (all sept, each 1 H, CHMe2,
J = 6.9 Hz); 6.73 (s, 1 H, C(5)H). 13C NMR (CDCl3), δ: 20.3,
21.1, 21.5 (Me); 26.9, 27.4, 29.3( CH(Me)2); 133.6 (C(5)H);
140.3 (C(6)); 146.9 (C(3)); 153.4 (C(5)); 180.6, 181.4 (O=C(1),
O=C(2)).
4ꢀHydroperoxyꢀ2ꢀhydroxyꢀ3,4,6ꢀtriisopropylcyclohexaꢀ2,5ꢀ
dienone (3). A solution of 3,4,6ꢀtriisopropylcatechol (1)
(10 mmol) in light petroleum (50 mL) was left in a loosely
covered beaker at ∼20 °C for 20 days. The precipitated large,
colorless columnar crystals of the hydroperoxide were separated
and recrystallized from heptane to give 1.1 g (43%) of comꢀ
pound 3, m.p. 107—109 °C. Determination of active oxygen by
iodometric titration gave an overestimated result because the
quinone formed also entered into the reaction together with
hydroperoxide 3. Found (%): C, 66.73; H, 9.00. C15H24O4.
Calculated (%): C, 67.13; H, 9.01. IR, ν/cm–1
: 970
(=CH def. vibr.); 1145, 1170 (Pri); 3420, 3320 (stretch. vibr.
of the alcohol and hydroperoxy groups in an associꢀ
ated form); 1645 (C=O); 1620 (C=C). 1H NMR (CDCl3),
δ: 0.71 (d, 3 H, C(4)(CH3)CHCH3, J = 6.9 Hz); 1.10 (d,
3 H, C(4)(CH3)CHCH3, J = 6.9 Hz); 1.12 (d, 3 H,
Experimental
NMR spectra were recorded on a Bruker Avance DPXꢀ200
1
instrument (200 МHz for H and 50 МHz for 13C). The followꢀ
C(6)(CH3)CHCH3, J = 6.9 Hz); 1.14 (d,
C(6)(CH3)CHCH3, J = 6.9 Hz); 1.29 (d,
C(3)(CH3)CHCH3, J = 7.0 Hz); 1.38 (d,
C(3)(CH3)CHCH3, J = 7.0 Hz); 2.12 (sept,
C(4)(CH3)CHCH3, J = 6.9 Hz); 2.72 (sept,
C(3)(CH3)CHCH3, J = 7.0 Hz); 3.01 (sept,
3
3
3
1
1
1
H,
H,
H,
H,
H,
H,
ing 2D NMR experiments were carried out: COSY (COSY45),
i.e., proton—proton correlation due to spin—spin coupling;
NOESY, i.e., proton—proton correlation due to dipole—dipole
interaction; and XHCORR, i.e., carbon—proton correlation due
to the spin—spin coupling between neighboring nuclei. The
XwinNMR 2.1 program was used for processing. In NOESY
experiments, the mixing time was 250 ms. Xꢀray diffraction study
was performed on a Bruker SMART 1000 CCD diffractometer
(T = 193 K, MoꢀKα radiation). ESR spectra were run on a
Bruker ER200DꢀSRC instrument operating at 9.5 GHz. IR specꢀ
tra were measured on a Perkin—Elmer 577 spectrometer in Nujol.
3,4,6ꢀTriisopropylcatechol (1). Concentrated H2SO4
(0.81 mol) was slowly added with vigorous stirring to a boiling
mixture of catechol (0.2 mol), propanꢀ2ꢀol (0.8 mol), and
nꢀheptane (60 mL). The reaction mixture was stirred for 5 h.
C(6)(CH3)CHCH3, 3J = 6.9 Hz, 4J = 1.0 Hz); 6.65 (s, OH),
6.76 (d, 1 H, C(5)H, J = 1.0 Hz); 7.60 (br.s, 1 H, OOH).
13C NMR (CDCl3), δ: 17.5 (C(4)(CH3)CHCH3); 17.9
(C(4)(CH3)CHCH3); 18.9 (C(3)(CH3)CHCH3); 19.5
(C(3)(CH3)CHCH3); 21.4 (C(6)(CH3)CHCH3); 22.2
(C(6)(CH3)CHCH3); 26.4 (C(3)CHMe2); 26.8 (C(6)CHMe2);
33.1 (C(4)CHMe2); 87.6 (C(4)); 134.6, 145.8, 145.9 (C(2), C(3),
C(6)); 142.5 (C(5)H); 181.5 (C(1)). The 1H and 13C NMR
signals were assigned using COSY, NOESY, DEPT, and
XHCORR techniques.

1852
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 8, August, 2003
Abakumov et al.
XꢀRay diffraction study of compound 3 gave 3426 indepenꢀ
Table 3. Gеometric parameters of hydrogen bonds in the crystal
structure of hydroperoxide 3 (see Fig. 3)
dent reflections (Rint = 0.0239). Crystal data at T = 193 K:
–
C15H24O4, triclinic system, space group P1, a = 7.0974(12) Å,
b = 9.3995(16) Å, c = 11.944(2) Å, α = 80.288(4)°,
Parameter
Value
β = 85.954(4)°, γ = 73.028(4)°, V = 751.0(2) Å3, Z = 2, dcalc
=
1.187 g cm–3
.
Distance
d/Å
O(2A)—H(O(2A))
O(1C)...(H(O(2)))
O(2A)...O(1C)
O(2C)—H(O(2C))
O(1A)...H(O(2C))
O(1A)...O(2C)
O(4B)—H(O(4B))
O(2C)...H(O(4B))
O(4B)...O(2C)
0.88(3)
1.95(3)
2.7537(19)
0.88(3)
2.15(3)
2.6298(19)
0.84(3)
2.04(3)
2.881(2)
ω/deg
The absorption corrections were applied using the SADABS
program package (Tmin = 0.9710, Tmax = 0.9916). The structure
of 3 (see Fig. 2) was solved by the direct method followed by
calculation of difference Fourier series and refined by the fullꢀ
matrix leastꢀsquares method for the structural factors F 2. All the
nonhydrogen atoms were refined with anisotropic thermal paꢀ
rameters. The H atoms were located from the difference Fourier
synthesis and refined in the isotropic approximation. The final
Rꢀfactors were (I > 2σ(I )): R1 = 0.0436, wR2 = 0.0989. All
calculations were carried out using a SHELXTL 11 (5.10) proꢀ
gram package.
Angle
O(2A)—H(O(2A))...O(1C)
O(1A)...H(O(2C))—O(2C)
O(4B)—H(O(4B))...O(2C)
151(2)
113(2)
172(3)
Selected bond lengths and angles in the molecule of hydropꢀ
eroxide 3 and the geometric parameters of hydrogen bonds in
the crystal structure of hydroperoxide 3 (see Fig. 3) are listed in
Tables 1—3.
Silochrome (using a 50 : 1 hexane—ethyl acetate mixture as the
eluent) in order to isolate reaction products in a pure state. The
yields are given in molar percent.
Decomposition of hydroperoxide 3. Hydroperoxide 3 (0.54 g,
2.21 mmol) was heated for 0.5 h at 115—120 °C in an evacuated
tube; this was accompanied by vigorous bubbling and the colorꢀ
less melt acquired a darkꢀred color. After gas evolution ceased,
heating was terminated, the reaction mixture was cooled, and
the liquid and gaseous reaction products were separated. The
glassy residue (0.50 g) was dissolved in hexane and chromaꢀ
tographed on a column with Silochrome. Elution with hexane
gave three zones: a colorless (1), a lightꢀyellow (2), and a darkꢀ
yellow (3). Each of the three zones was subjected to preliminary
qualitative TLC analysis on Silufol UVꢀ254 plates with a 50 : 1
heptane—acetyl acetate solvent mixture. The faintly colored
spots formed on the plates were visualized by iodine vapor. Then
each zone was chromatographed once again on a column with
Compounds 5, 6, and 7 were isolated from zone 1.
2ꢀIsopropoxyꢀ3,5,6ꢀtriisopropylphenol (5), yield 0.02 g (4%),
1
white crystals. H NMR (CDCl3), δ: 1.21 (d, 12 H, Me, J =
6.9 Hz); 1.28 (d, 6 H, Me, J = 6.9 Hz); 1.34 (d, 6 H, OCHMe2,
J = 6.2 Hz); 3.18 (sept, 1 H, C(6)CHMe2, J = 6.9 Hz); 3.19,
3.26 (both sept, each 1 H, CHMe2, J = 6.9 Hz); 4.07 (sept, 1 H,
OCHMe2, J = 6.2 Hz); 5.87 (s, 1 H, OH); 6.64 (s, 1 H, C(4)H).
The 1H NMR signals were assigned using the COSY and NOESY
techniques.
2ꢀIsopropoxyꢀ3,4,6ꢀtriisopropylphenol (6), yield ∼0.008 g
1
(∼1.5%). H NMR (CDCl3), δ: 1.21, 1.23 (both d, each 6 H,
Me, J = 6.9 Hz); 1.33 (d, OCHMe2, J = 6.2 Hz); 1.34 (d, 6 H,
Me, J = 7.3 Hz); 3.19, 3.30 (both sept, each 1 H, CHMe2, J =
6.9 Hz); 3.48 (sept, 1 H, CHMe2, J = 7.3 Hz); 4.03 (sept, 1 H,
OCHMe2, J = 6.2 Hz); 5.67 (s, 1 H, OH); 6.84 (s, 1 H, C(4)H).
The 1H NMR signals were assigned using the COSY and NOESY
techniques.
Table 1. Selected bond lengths in the molecule of hydroperꢀ
oxide 3
Bond
d/Å
Bond
d/Å
3,4,6ꢀTriisopropyloxepineꢀ2,7ꢀdione (7), yield 0.04 g (7%).
1H NMR (CDCl3), δ: 1.08, 1.17, 1.22 (all d, each 6 H, Me, J =
6.9 Hz); 2.92 (sept, 1 H, C(6)CHMe2, 3J = 6.9 Hz, 4J = 1.2 Hz);
3.02, 3.04 (both sept, each 1 H, CHMe2, J = 6.9 Hz); 6.41 (d,
1 H, C(5)H, 4J = 1.2 Hz). 13C NMR (CDCl3), δ: 21.4, 21.53,
21.53 (Me); 28.9, 29.1, 32.8 (CHMe2); 128.4 (C(5)H);
137.4, 142.6, 142.7 (C(3), C(4), C(6)); 162.1, 162.3 (O=C(2),
O=C(7)). The structure of this product was additionally conꢀ
firmed by an alternative synthesis according to a known proceꢀ
dure.12 The NMR spectra of compound 7 isolated from the
product mixture after decomposition of hydroperoxide 3 fully
coincided with the spectra of this compound synthesized by the
known procedure.
O(1)—C(1)
O(2)—C(2)
O(2)—H(O(2))
O(3)—C(4)
O(3)—O(4)
1.233(2)
1.371(2)
0.88(3)
1.443(2)
1.4679(19)
O(4)—H(O(4))
C(2)—C(3)
C(3)—C(4)
C(5)—C(6)
0.84(3)
1.340(2)
1.510(3)
1.336(3)
Table 2. Selected bond angles in the molecule of hydroperꢀ
oxide 3
Angle
ω/deg
C(4)—O(3)—O(4)
O(3)—O(4)—H(O(4))
O(1)—C(1)—C(2)
O(1)—C(1)—C(6)
C(3)—C(2)—O(2)
O(2)—C(2)—C(1)
O(3)—C(4)—C(5)
O(3)—C(4)—C(3)
107.43(12)
93(2)
Compounds 4 and 8 were isolated from zone 2.
3ꢀHydroxyꢀ2,5ꢀdiisopropylbenzoꢀ1,4ꢀquinone (4), yield
0.112 g (24%), bright yellow, m.p. 56—58 °C (from pentane).
Found (%): C, 69.32; H, 7.70. C12H16O3. Calculated (%):
C, 69.20; H, 7.74. IR (mineral oil), ν/cm–1: 1610 (=C—); 1640,
118.87(17)
121.70(16)
122.94(16)
113.94(15)
109.24(14)
109.96(15)
1
1660 (C=O); 3380, 3280 (OH). H NMR (CDCl3), δ: 1.15 (d,
6 H, C(5)CHMe2, J = 6.8 Hz); 1.23 (d, 6 H, C(2)CHMe2, J =
7.1 Hz); 3.00 (sept, 1 H, C(5)CHMe2, 3J = 6.8 Hz, 4J = 1.1 Hz);

Hydroperoxycyclohexadienone
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 8, August, 2003
1853
3.19 (sept, 1 H, C(2)CHMe2, J = 7.1 Hz); 6.41 (d, 1 H, C(6)H,
4J = 1.1 Hz); 7.06 (s, 1 H, OH). 13C NMR (CDCl3), δ: 19.9
(C(2)CH(CH3)2); 21.3 (C(5)CH(CH3)2); 24.2 (C(2)CHMe2);
26.7 (C(5)CHMe2); 125.1 (C(2)); 133.1 (C(6)H); 149.9 (C(5));
151.0 (C(3)OH); 184.0 (O=C(4)); 187.9 (O=C(1)). The 1H and
13C NMR signals were assigned using COSY and XHCORR
techniques.
2. T. Funabuki, I. Yoneda, M. Ishikawa, M. Ujiie, Y. Nagai,
and S. Yoshida, J. Chem. Soc., Chem. Commun., 1994, 1453.
3. T. Funabuki, A. Mizoguchi, T. Sugimoto, S. Tada, M. Tsuji,
H. Sakamoto, and S. Yoshiba, J. Am. Chem. Soc., 1986,
108, 2921.
4. Y. Sawaki and C. S. Foote, J. Am. Chem. Soc., 1983,
105, 5035.
2ꢀHydroxyꢀ3,4,6ꢀtriisopropylbenzoꢀ1,4ꢀquinone (8), yield
0.008 g (1.5%). H NMR (CDCl3), δ: 1.23, 1.27, 1.28 (all d,
each 6 H, Me, J = 7.0 Hz); 3.19, 3.26, 3.26 (all sept, each 1 H,
CHMe2, J = 7.0 Hz); 7.10 (s, OH).
Zone 3 was separated to give 3,4,6ꢀtriisopropylcatechol (1),
yield 0.18 g (38%), and 3,4,6ꢀtriisopropylbenzoꢀ1,2ꢀquinone (2),
yield 0.10 g (21%).
5. V. N. Glushakova, N. A. Skorodumova, V. I. Nevodchikov,
L. G. Abakumova, N. P. Makarenko, V. K. Cherkasov, and
N. O. Druzhkov, Izv. Akad. Nauk, Ser. Khim., 1999, 943
[Russ. Chem. Bull., 1999, 48, 934 (Engl. Transl.)].
6. M. Ochiai, A. Nakanishi, and A. Yamada, Tetrahedron Lett.,
1997, 38, 3927.
1
7. S. Braun, H. Kalinowski, and S. Berger, 100 and More NMR
Experiments, Weinheim, VCH, 1996, 210 pp.
The authors are grateful to L. H. Zakharov for Xꢀray
diffraction study.
8. V. D. Pokhodenko, Fenoksil´nye radikaly [Phenoxyl Radiꢀ
cals], Naukova dumka, Kiev, 1969, 194 pp. (in Russian).
9. V. E. Zubarev, Metod spinovykh lovushek. Primenenie v khimii,
biologii, meditsine [Spin Traps. The Use in Chemistry, Biology,
and Medicine], Izdꢀvo MGU, Moscow, 1984, 186 pp. (in
Russian).
10. M. I. Kabachnik, N. N. Bubnov, A. I. Prokofiev, and S. P.
Solodovnikov, Science Rev., Ser. B, 1981, 3, XXIV, 197.
11. G. Sheldrick, Bruker XRD, Madison, Wisconsin
(USA), 1998.
These studies were financially supported by the Rusꢀ
sian Foundation for Basic Research (RFBR Project No.
01ꢀ03ꢀ33065). The spectroscopic measurements were perꢀ
formed at the Analytical Center of the Institute of Orgaꢀ
nometallic Chemistry of the Russian Academy of Sciꢀ
ences (RFBR Project No. 00ꢀ03ꢀ40116).
12. C. Grundnman, Methoden der organishen Chemie, Houben
Weyl, Stuttgart, 1977, VII/3b, 1.
References
1. L. M. Engelhardt, F. R. Hewgill, J. M. Stewart, and A. H.
Received March 12, 2003;
White, J. Chem. Soc., Perkin Trans. 1, 1988, 1845.
in revised form May 20, 2003