Alkylation of catechol with cyclohexene. Novel sterically hindered o-quinones and catechols

Article abstract of DOI:10.1007/s11172-020-3051-9

A synthetic procedure for the preparation of sterically hindered catechols and o-quinones by the reaction of catechol with cyclohexene was developed. Novel cyclohexyl substituted catechols displayed remarkable stability during redox transformations and could be used as redoxactive ligands.

Full text of DOI:10.1007/s11172-020-3051-9

Russian Chemical Bulletin, International Edition, Vol. 69, No. 12, pp. 2383—2389, December, 2020
2383
Alkylation of catechol with cyclohexene.
Novel sterically hindered o-quinones and catechols
T. N. Kocherova, N. O. Druzhkov, K. A. Martyanov, A. S. Shavyrin, M. V. Arsenyev,
T. I. Kulikova, E. V. Baranov, V. A. Kuropatov, and V. K. Cherkasov
G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences,
49 ul. Tropinina, 603950 Nizhny Novgorod, Russian Federation.
Fax: +7 (831) 462 7497. E-mail: viach@iomc.ras.ru
A synthetic procedure for the preparation of sterically hindered catechols and o-quinones
by the reaction of catechol with cyclohexene was developed. Novel cyclohexyl substituted cat-
echols displayed remarkable stability during redox transformations and could be used as redox-
active ligands.
Key words: o-quinones, catechols, redox-active ligands, alkylation, cyclohexene.
The development of new approaches for the synthesis
of substituted catechols remains relevant, despite the fact
that these compounds have been objects of study for many
decades. Catechols are used as biologically active com-
pounds,1 food components,2 and pharmaceuticals.3—8
A characteristic feature of catechols is their redox
activity. Catechols are capable of reversibly changing their
oxidation state, successively transforming into semiqui-
nones and o-quinones both in the non-coordinated form
and as a dioxolene ligand in the coordination sphere of
the metal.9,10 The redox activity of dioxolene ligands
underlies the most interesting phenomena discovered
during the study of their metal complexes, in particular,
the temperature-dependent reversible bending of crystals
of rhodium semiquinone complexes,11 as well as spin
crossover on cobalt semiquinone complexes.12
In contrast to catechols, their oxidized forms are usu-
ally very reactive. An example is the Diels—Alder cyclo-
addition of o-quinones.13 The stability of the oxidized
forms of dioxolene ligands is increased by steric blockage
of the chelating site, usually with bulky tert-butyl sub-
stituents which provide protection for both the dioxolene
fragment and the peripheral positions 4 and 5 of the
o-quinone ring.14 The peripheral positions 4 and 5 are
used for additional functionalization. In such substituted
derivatives, tert-butyl groups experience steric repulsion
from carbonyl quinone groups, as well as from substituents
at positions 4 and 5 of the ring, which results in significant
distortions of the o-quinone skeleton.15—18 The distortion
can be reduced by decreasing the bulkiness of protecting
substituents, for example, by replacing tertiary carbon
substituents with secondary ones.
Results and Discussion
There are many approaches for introduction of alkyl
substituents into the aromatic ring. Some of them, such
as free radical reactions and reactions with organometal-
lic compounds,19,20 have rather limited application. The
most universal is the Friedel—Crafts alkylation. This
method is used for the preparation of tert-butyl-substituted
o-quinones (Scheme 1).14 The composition of the alkyl-
ation products depends significantly on the nature of the
electrophilic agent (alcohol, halogenated hydrocarbon, or
alkene), catalyst, solvent, and reaction temperature. The
alkylation of catechol with tertiary alcohols at an alco-
Scheme 1
Reagents and conditions: i. ButOH or H2C=CMe2, ii. Ph2CHOH.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2383—2389, December, 2020.
1066-5285/20/6912-2383 © 2020 Springer Science+Business Media LLC

Kocherova et al.
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Russ. Chem. Bull., Int. Ed., Vol. 69, No. 12, December, 2020
hol : catechol molar ratio 2 : 1 gives a mixture of 3,5- and
3,6-disubstituted derivatives. An excess amount of alkyl-
ating agent does not lead to the formation of any additional
products.
The mixture of catechols remaining in the mother liquor
was oxidized with potassium ferricyanide in an alkaline
medium to the corresponding quinones. Most of 3,6-di-
cyclohexyl-o-benzoquinone (4) precipitated during re-
crystallization of the mixture of quinones from hexane.
3,4,6-Tricyclohexyl-o-benzoquinone (6) was isolated from
the mother liquor by column chromatography. Products 1
and 3 were obtained in pure form by reduction of o-quin-
ones 4 and 6 with hydrazine hydrate (see Scheme 2).
Catechols 1—3 are colorless and air-stable solids. The
corresponding quinones 4—6 are also stable on storage in
air at room temperature.
The quantitative composition of alkylation products
1—3 was monitored by reverse phase chromatography.
Preliminary experiments showed that the mixture of cate-
chols 1—3 is rather difficult to separate chromatographi-
cally; therefore, the reaction mixture prior to analysis was
oxidized with an excess of potassium ferricyanide in an
alkaline medium to quinones. Table 1 shows the results of
the analysis of the composition of the mixture of alkyla-
tion products of catechol with cyclohexene based on the
data of reverse phase chromatography and 1H NMR spec-
troscopy.
The available data on the regioselectivity and quantita-
tive composition of the alkylation products of catechol
with secondary alcohols and alkenes are rather contradic-
tory. In the case of benzhydrol, a 4,5-disubstituted prod-
uct is formed in >50% yield, 3,5-di- and 3,4,6-trisubsti-
tuted derivatives are formed in smaller amounts,21 while
a symmetric 3,6-disubstituted product is not formed at all
(see Scheme 1). It is noted that alkylation of catechol with
cyclohexene in the presence of aluminum phenoxide leads
to 3,5- and 3,6-disubstituted derivatives, with their ratio
varying depending on the concentration of the catalyst
and the process temperature.22 The formation of 3,4,6-tri-
isopropyl-substituted catechol upon alkylation with pro-
pan-2-ol is mentioned.23
In the present work, we studied the possibility of con-
trolling the acid-catalyzed alkylation of catechol with
cyclohexene. The reactions were carried out by heating
a neat mixture of the starting compounds at a molar ratio
of catechol : cyclohexene = 1 : 2.5. Sulfuric, polyphos-
phoric, and perchloric acids were used as the catalyst.
Preference was given to perchloric acid, since sulfuric and
polyphosphoric acids caused polymerization of the alkyl-
ating agent, which resulted in significant resinification.
The conditions for the process were selected taking into
account the data24 on the alkylation of phenols with cyclo-
hexene. According to these data, the alkylation proceeds
most efficiently at 120 C without solvent using 57% per-
chloric acid as a catalyst.
Using 1H NMR spectroscopy, it was possible to com-
pare the quantitative composition of the primary mixture
of catechols and the corresponding mixture of o-quinones
(see Table 1). For this purpose, we compared the integral
intensities of the signals for protons bonded directly to the
catechol (quinone) ring of the molecule. Both the catechol
and the quinone signals are well resolved in this spectral
region. The chemical shifts for the catechol protons of
compounds 1 and 3 are δ 6.72 and 6.61, respectively. Two
nonequivalent catechol ring protons of 3,5-dicyclohexyl-
catechol (2) are observed at δ 6.58 and 6.62, with the
second signal overlapping with signals of compound 3. For
this reason, the amount of product 3 in the reaction mix-
ture was determined as the difference between the integral
We found that the reaction of catechol with cyclo-
hexene gives 3,6-di-, 3,5-di-, and 3,4,6-trialkylated
products 1—3, respectively (Scheme 2). The products were
separated as follows. The major part of 3,5-dicyclohexyl-
catechol (2) was isolated by recrystallization from hexane.
Scheme 2

Alkylation of catechol
Russ. Chem. Bull., Int. Ed., Vol. 69, No. 12, December, 2020
2385
Table 1. Composition of the mixture of alkylation products of
catechol with cyclohexene
C(7A)
Method
Object
of study
Product (mol.%)
C(13A)
1 or 4
2 or 5
3 or 6
HPLC
After oxidation
(quinones)
Primary mixture
(catechols)
After oxidation
(quinones)
18
19
17
68
14
17
18
C(3A)
C(2A)
C(4A)
1H NMR
1H NMR
64
65
C(5A)
O(2A)
C(6A)
C(19A)
C(1A)
intensities of the signal in the region δ 6.61—6.62 and the
signal of the proton of catechol 2 at δ 6.58. Analysis of the
1H NMR spectra of the mixture of quinones 4—6 was
somewhat simpler, since the proton signals of the quinone
ring of different products do not overlap. Thus, the signals
at δ 6.66 and 6.64 belong to the protons of quinones 4 and
6, respectively, while the protons of quinone 5 appear as
singlets at δ 6.07 and 6.59.
O(1A)
Fig. 1. The structure of the independent molecule A of o-quinone 6.
Thermal ellipsoids are shown with a 30% probability. Hydrogen
atoms are omitted.
The used procedures for determining the quantitative
composition of the mixture of alkylation products give
similar results (see Table 1). The predominant reaction
product was 3,5-dialkylated derivative 2. 3,6-Dicyclo-
hexylcatechol 1 and 3,4,6-tricyclohexylcatechol 3 are
formed in approximately equal proportions.
Table 2. Principal bond lengths (d) in two in-
dependent molecules A and B in the unit cell of
o-quinone 6
Bond
d/Å
It was indicated above that a 25% excess of cyclohex-
ene was used in the alkylation of catechol. It is obvious
that this excess amount is a reason of the formation of the
trialkylated product. At the same time, with a stoichio-
metric ratio of catechol and cyclohexene (1 : 2) the num-
ber of products would increase, namely, isomeric mono-
alkylated 3- and 4-cyclohexylcatechols were added to
dicyclohexyl derivatives 1—3. The question about the
mechanism of formation and the precursor of 3,4,6-tri-
cyclohexylcatechol 3 requires a separate study. The avail-
able data allow suggestion that the rate of formation of
this compound is comparable with the rate of introduction
of the second cyclohexyl group in the catechol ring.
Quinones 4—6 and catechols 1—3 were characterized
by physicochemical methods. The IR spectra of quinones
exhibit strong bands in the region of 1640—1700 cm–1
characteristic of the stretching vibrations of carbonyl
groups in sterically hindered o-quinones.
3,4,6-Tricyclohexyl-o-quinone (6) was characterized
by X-ray diffraction analysis. The unit cell contains two
independent molecules of o-quinone 6 slightly differing
in geometrical characteristics. The structural parameters
of compound 6 are typical of sterically hindered o-quinones
(Fig. 1, Tables 2 and 3). In particular, an alternation of
bond lengths characteristic of o-quinones is observed in
the central six-membered ring. Deviation from the planar
structure is observed in the geometry of the quinone ring
because of the close spatial arrangement of two bulky
A
B
O(1)—C(1)
O(2)—C(2)
C(1)—C(2)
C(2)—C(3)
C(3)—C(4)
C(4)—C(5)
C(5)—C(6)
C(1)—C(6)
C(3)—C(7)
C(4)—C(13)
C(6)—C(19)
1.222(4)
1.212(4)
1.540(4)
1.481(4)
1.357(4)
1.475(4)
1.346(4)
1.460(4)
1.525(4)
1.523(4)
1.519(4)
1.215(4)
1.212(4)
1.540(4)
1.485(4)
1.356(4)
1.471(4)
1.343(4)
1.465(4)
1.517(4)
1.516(4)
1.509(5)
cyclohexyl substituents at positions 3 and 4. In addition,
in order to minimize steric interactions the substitu-
ents at positions 3 and 4 in the crystal structure are
forced to be turned perpendicular to the plane of the
o-quinone ring.
The study of the electrochemical characteristics of new
o-quinones (Table 4) showed that the substituted deriva-
tives 4 and 5 are stronger acceptors than their tert-butyl
counterparts.* The first reduction potential of compounds
4 and 5 is shifted towards positive values by ~0.1 V com-
* S. V. Norkov, A. V. Cherkasov, A. S. Shavyrin, M. V. Arsenyev,
V. A. Kuropatov, V. K. Cherkasov, Beilstein J. Org. Chem., 2020;
in press.

Kocherova et al.
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Russ. Chem. Bull., Int. Ed., Vol. 69, No. 12, December, 2020
Table 3. Basic crystallographic data and structure refinement
statistics for compound 6
a
Parameter
Value
Molecular formula
C24H34O2
354.51
Molecular weight
Т/K
100(2)
Crystal system
Orthorhombic
Pbca
11.1571(9)
20.4996(16)
35.525(3)
90
Space group
a/Å
b/Å
c/Å
3438
3442
3446 H/G
/deg
/deg
90
90
/deg
b
V/Å3
8125.0(11)
16
Z
d/g cm–3
1.159
/mm–1
0.071
F(000)
3104
Crystal size/mm
-Range for data collection/deg
Indices of h, k, l regions
0.220.140.06
2.07—25.35
–13 ≤ h ≤ 13
–24 ≤ k ≤ 24
–42 ≤ l ≤ 42
103067
7447 (0.1167)
1.055
0.0816/0.1509
0.1308/0.1732
0.271/–0.228
Number of collected reflections
Number of unique reflections (Rint
GOOF (F2)
)
3438
3442
3446 H/G
R1/wR2 (I > 2 (I))
R1/wR2 (for all parameters)
Residual electron density
/e Å–3, max/min
c
Table 4. Reduction potentials of quinones 4—6
according to cyclic voltammetry*
Quinone
–E (1)
–E (2)
½
½
V
4
5
6
0.43
0.47
0.53
0.76
0.91
0.77
3438
3441
3444 H/G
Fig. 2. EPR spectra of mono-reduced potassium derivatives of
o-quinones 4 (a), 5 (b), and 6 (c) recorded in a THF solution at
293 K.
* Ag/AgCl/KCl (sat.), MeCN, C = 5•10–3 mol L–1
.
gradually decreases to almost zero, which is explained by
the formation of diamagnetic catecholate species. The
reduced forms of quinones are relatively stable in solution
in the absence of oxygen. Thus, the intensity of the EPR
signal of semiquinone complexes in a sealed tube in the
absence of metallic potassium remains unchanged for
several hours.
The spin density distribution in the semiquinone ligand
is generally similar to the distribution observed for their
counterparts with tert-butyl substituents.25 At the same
time, the presence of a proton at the tertiary carbon atom
of cyclohexyl substituents in quinones 4—6 allows evalu-
pared to tert-butyl derivatives. In addition, a decrease in
the interval between the first and second reduction poten-
tials by ~0.15 V is observed for cyclohexyl o-quinones. The
first and second reduction waves for all investigated quin-
ones can be characterized as quasi-reversible and one-
electron ones.
The ability of quinones 4—6 to one-electron stepwise
reduction in solution is also confirmed by reactions with
alkali metals. The EPR spectroscopy data show that the
reduction of o-quinones 4—6 with potassium metal at the
first stage gives paramagnetic semiquinone adducts (Fig. 2).
With further reduction, the intensity of the EPR signal

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Russ. Chem. Bull., Int. Ed., Vol. 69, No. 12, December, 2020
2387
Table 5. Parameters of EPR spectra of mono-reduced potassium derivatives of quinones 4—6 in
solution in THF*
Quinone
g-Factor
HFS constants for aromatic ring protons
(methine protons of cyclohexyl substituent)/G**
3
4
5
6
4
5
6
2.0047
2.0047
2.0046
— (0.50)
— (0.65)
— (0.10)
(3.13) —
(3.13) —
— (1.06)
(3.13) —
— (1.80)
(3.13) —
— (0.50)
(0.715) —
— (0.47)
* The spectra were recorded at 293 К.
** The positions of aromatic protons for which the interaction with an unpaired electron is observed
are given in accordance with the notation in Scheme 1. The experimentally measured HFS constant
values on protons were refined using the simulated spectra.
Supporting electrolyte was 0.1 M Bu4NClO4 recrystallized twice
from aqueous EtOH and vacuum dried (48 h) at 50 C. The
concentration of o-benzoquinones 4—6 in acetonitrile was
ation of the spin density at positions of the quinone ring
bound to the alkyl groups.
The hyperfine splitting constant values for hydrogen
atoms observed for mono-reduced potassium derivatives
of o-quinones 4—6 are given in Table 5. The correlation
of the constant values with specific atoms in the semiqui-
none ligand was carried out by analogy with the previously
described derivatives of bis(diphenylmethyl)-substituted
o-quinones.21 It should be noted that the character of the
spin density distribution in cyclohexyl semiquinonate
species are very similar to that in corresponding bis-
(diphenylmethyl)-substituted derivatives.
5•10–3 mol L–1
.
HPLC was carried out on a Knauer liquid chromatograph
equipped with a UV detector ( = 254 nm) and a steel column
100×6 mm in size filled with a Silasorb 600 SPH sorbent; eluent
hexane—THF, 150 : 1, the eluent flow rate was 1.5 mL min–1
.
Solvents were purified and dehydrated using standard pro-
cedures.26 Commercially available catechol and cyclohexene
were used without prior purification.
Samples of potassium semiquinolates for recording EPR
spectra were prepared according to the procedure described
earlier.27
In conclusion, we have developed a convenient pro-
cedure for the preparative synthesis of cyclohexyl-substi-
tuted o-quinones, the degree of steric protection of the
dioxolene fragment in which is lower than in the tert-
butyl analogs. Despite the reduced hindering, the new
o-quinones and their reduced derivatives are stable and
can be used as redox-active dioxolene ligands for the
preparation of metal complexes. It is important that the
reaction of catechol with cyclohexene gives a symmetric
3,6-disubstituted derivative, which is absent in the products
of the alkylation of catechol with benzhydrol.
Alkylation of catechol. Cyclohexene (25 mL, 0.25 mol) was
slowly added dropwise to a melt of catechol (11 g, 0.1 mol) with
perchloric acid (2 mL, 0.02 mol) in a flat-bottom flask equipped
with a condenser at 120 С with continuous stirring. After cool-
ing, the solidified reaction mixture was dissolved in diethyl ether,
washed from acid with water until neutral pH, and the solvent
was evaporated under reduced pressure on a rotary evaporator.
The solid residue was dissolved in hexane (200 mL) with heating;
3,5-dicyclohexylcatechol (2) (10.5 g, 38%) was crystallized upon
cooling the solution to –18 С. The solvent was evaporated from
the mother liquor under reduced pressure, the residue was dis-
solved in diethyl ether and the solution was oxidized with a solu-
tion of K3Fe(CN)6 (100 g), KOH (5 g), and Na2CO3 (10 g) in
water (250 mL) with magnetic stirring. Then, the organic layer
was washed with water until the washings were neutral and dried
with anhydrous Na2SO4, the solvent was evaporated under re-
duced pressure. The solid residue was dissolved in hexane
(100 mL) upon heating, quinone 4 (2.5 g) was precipitated from
the solution at –18 С. The remaining mixture of o-quinones
was separated by column chromatography (eluent hexane—
ethyl acetate (25 : 1), silica gel (0.063—0.2 mm, Macherey-
Nagel)) and crystallized from hexane to isolate quinone 6 (4.9 g,
14%), quinone 4 (3.3 g, 12%) (total from the reaction mixture
and after column chromatography), and quinone 5 (5.4 g, 20%).
Crystals of 3,4,6-tricyclohexyl-o-quinone (6) suitable for X-ray
diffraction analysis were obtained after recrystallization upon
cooling to –18 С from hexane—diethyl ether (10 : 1).
Experimental
NMR spectra were recorded on a Bruker Avance III 400
spectrometer (400 (1H) and 100 MHz (13C and DEPT)). EPR
spectra were obtained on a Bruker EMX 8/2.7 spectrometer. The
WinEPR SimFonia v1.25 program (Bruker) was used for spectra
simulation. IR spectra were recorded on a Bruker Vertex 70 FT-IR
spectrometer with a RAM II diffuse reflectance sampling acces-
sory. The elemental analysis was performed on an Elementar
vario EL cube automatic elemental analyzer (Germany).
The reduction potentials were measured by cyclic volt-
ammetry (CV) in a three-electrode cell using an Elins P-45X
potentiostat in acetonitrile in an argon atmosphere. The working
electrode was a stationary glassy carbon (GC) electrode with
a diameter of 2 mm, the auxiliary electrode was a platinum grid.
The reference electrode was Ag/AgCl/KCl (sat.) with a water-
3,6-Dicyclohexylbenzene-1,2-diol (1). Hydrazine hydrate was
added dropwise from a capillary to a solution of 3,6-dicyclohexyl-
о-quinone (4) (0.25 g, 1 mmol) in anhydrous methanol (10 mL)
with magnetic stirring until the solution was completely discol-
proof diaphragm. The potential sweep rate was 100 mV s–1
.

Kocherova et al.
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Russ. Chem. Bull., Int. Ed., Vol. 69, No. 12, December, 2020
ored. Product 1 was precipitated from the solution by the grad-
ual addition of water with constant vigorous stirring. The pre-
cipitate was collected by filtration, washed with water, and dried
under reduced pressure. A colorless powder. The yield was 0.14 g
(56%), m.p. 128—129 С. Found (%): C, 78.34; H, 9.48.
: 1.06—1.45 and 1.66—1.84 (both m, 5 H each, CH2 in cyclo-
С6H11); 2.48—2.65 (m, 1 H, CH in cyclo-С6H11); 6.66 (s, 1 H).
13C NMR (CDCI3), : 26.1; 26.4; 32.2; 36.6; 133.6; 146.4; 181.0.
3,5-Dicyclohexylcyclohexa-3,5-diene-1,2-dione (5). Cherry-
red crystals, m.p. 47—48 С. Found (%): C, 79.25; H, 9.10.
C18H24O2. Calculated (%): C, 79.37; H, 8.88; O, 11.75. IR,
/cm–1: 1682 (s), 1660 (s), 1634 (s), 1597 (w), 1576 (m), 1464 (m),
1450 (s), 1400 (m), 1377 (m), 1357 (m), 1333 (m), 1315 (m),
1306 (m), 1290 (m), 1254 (s), 1240 (m), 1200 (m), 1180 (w),
1134 (w), 1118 (w), 1078 (w), 1030 (w), 1001 (w), 992 (w),
964 (w), 946 (m), 920 (w), 891 (m), 858 (m), 798 (m), 780 (w),
763 (w), 720 (w), 648 (w), 618 (w), 603 (w), 580 (w), 555 (w),
507 (w), 499 (w), 475 (w). 1H NMR (CDCl3), : 1.11—1.45 and
1.68—1.95 (both m, 10 H each, CH2 in cyclo-С6H11); 2.10—2.21
and 2.58—2.68 (both m, 1 H each, CH in cyclo-С6H11); 6.07 and
6.59 (both s, 1 H each, C(4)H and C(6)H). 13C NMR (CDCI3),
: 25.7 (CH2); 26.0 (CH2); 26.1 (CH2); 26.4 (CH2); 30.8 (CH2);
32.3 (CH2); 36.8 (CH); 44.9 (CH); 122.2 (CH); 135.5 (CH);
148.1 (C); 160.9 (C); 180.3 (C); 180.8 (C).
3,4,6-Tricyclohexylcyclohexa-3,5-diene-1,2-dione (6). Dark
cherry crystals, m.p. 136—137 С. Found (%): C, 81.37; H, 9.90.
C24H34O2. Calculated (%):C, 81.31; H, 9.67. IR, /cm–1: 1675 (s),
1653 (s), 1626 (m), 1562 (w), 1450 (s), 1400 (m), 1377 (m),
1360 (m), 1347 (m), 1325 (m), 1313 (m), 1289 (m), 1267 (m),
1253 (m), 1232 (m), 1208 (w), 1187 (w), 1177 (w), 1140 (w),
1127 (w), 1060 (w), 1047 (w), 1027 (w), 1000 (w), 985 (m),
964 (w), 928 (m), 892 (m), 878 (m), 850 (w), 842 (w), 833 (w),
800 (w), 788 (w), 734 (w), 714 (w), 669 (w), 656 (w), 588 (m),
532 (w), 505 (w), 488 (w), 459 (w). 1H NMR (CDCl3),
: 1.11—1.96 (m, 30 H, CH2 in cyclo-С6H11); 2.50—2.61,
2.63—2.75 and 2.78—2.88 (all m, 1 H each, CH in cyclo-С6H11);
6.72 (s, 1 H, H(5)). 13C NMR (CDCI3), : 25.7 (CH2);
25.8 (CH2); 25.9 (CH2); 26.1 (CH2); 26.4 (CH2); 27.1 (CH2);
30.2 (CH2); 30.7 (CH2); 32.2 (CH2); 36.8 (CH); 38.0 (CH);
40.6 (CH); 135.1 (CH); 140.0 (C); 145.7 (C); 153.1 (C);
180.7 (C); 181.9 (C).
C18H26O2. Calculated (%): C, 78.79; H, 9.55. IR, /cm–1
:
3580—3100 (v.br), 1630 (w), 1611 (w), 1577 (w), 1550 (w), 1504 (m),
1350 (s), 1295 (s), 1260 (s), 1235 (s), 1209 (s), 1175 (s), 1131 (s),
1087 (m), 1075 (m), 1050 (m), 1030 (m), 1017 (m), 975 (s),
937 (s), 920 (m), 890 (m), 850 (w), 815 (m), 800 (s), 766 (w),
754 (m), 732 (m), 630 (m), 590 (w), 571 (w), 532 (m), 493 (m),
466 (m). 1H NMR (CDCl3), : 1.14—1.98 (m, 20 H, CH2 in
cyclo-С6H11); 2.58—2.80 (m, 2 H, CH in cyclo-С6H11); 5.12
(s, 2 H, OH); 6.72 (s, 2 H, C(4) and C(5)). 13C NMR (CDCI3),
: 26.2 (CH2); 27.0 (CH2); 33.1 (CH2); 37.5 (CH); 117.9 (CH);
131.0 (C); 140.6 (C).
3,5-Dicyclohexylbenzene-1,2-diol (2). A colorless powder.
The yield was 10.5 g (38%), m.p. 118—119 С. Found (%):
C, 78.16; H, 9.34. C18H26O2. Calculated (%): C, 78.79; H, 9.55.
IR, /cm–1: 3585—3076 (v.br), 1714 (w), 1620 (m), 1600 (m),
1506 (s), 1485 (m), 1460 (s), 1446 (s), 1378 (s), 1366 (s), 1346 (m),
1338 (m), 1296 (s), 1264 (s), 1244 (s), 1229 (s), 1184 (s), 1145 (m),
1134 (m), 1122 (m), 1078 (w), 1043 (w), 1030 (w), 1010 (w),
972 (s), 955 (s), 920 (w), 890 (w), 870 (w), 848 (s), 813 (w), 795 (w),
778 (m), 745 (m), 722 (m), 640 (m), 610 (w), 597 (w), 522 (w),
498 (w), 484 (w). 1H NMR (CDCl3), : 1.13—1.52 and 1.67—1.97
(both m, 10 H each, CH2 in cyclo-С6H11); 2.31—2.46 and
2.70—2.87 (both m, 1 H each, CH in cyclo-С6H11); 5.04 and
5.06 (both s, 1 H each, OH); 6.58 and 6.62 (both s, 1 H each,
C(4)H and C(6)H). 13C NMR (CDCI3), : 26.2 (CH2); 26.3
(CH2); 26.9 (CH2); 27.0 (CH2); 33.1 (CH2); 34.7 (CH2); 37.7
(CH); 44.2 (CH); 110.9 (CH); 117.2 (CH); 133.9 (C); 138.9 (C);
140.6 (C); 142.7 (C).
3,4,6-Tricyclohexylbenzene-1,2-diol (3) was obtained from
3,4,6-tricyclohexyl-о-quinone (6) similar to catechol 1. A color-
less powder. The yield was 0.22 g (61%), m.p. 158—159 С.
Found (%): C, 81.06; H, 9.92. C24H36O2. Calculated (%):
C, 80.85; H, 10.18. IR, /cm–1: 3630—3090 (v.br), 1701 (w),
1678 (w), 1670 (w), 1654 (w), 1612 (m), 1576 (m), 1489 (s),
1348 (s), 1325 (m), 1297 (s), 1282 (s), 1262 (s), 1232 (s), 1226
(s), 1216 (s), 1193 (s), 1180 (s), 1136 (s), 1126 (m), 1080 (m),
1055 (m), 1026 (m), 1010 (m), 977 (m), 919 (m), 891 (m),
849 (m), 840 (w), 808 (w), 803 (w), 787 (w), 770 (w), 735 (w),
720 (w), 710 (w), 680 (w), 658 (w), 607 (w), 594 (w), 555 (w),
503 (w). 1H NMR (CDCl3), : 1.14—2.22 (m, 30 H, CH2
in сyclo-С6H11); 2.54—2.76 (m, 2 H, CH in cyclo-С6H11);
2.77—2.91 (m, 1 H, CH in cyclo-С6H11); 4.77 and 5.41 (both s,
1 H each, OH); 6.61 (s, 1 H, H(5)). 13C NMR (CDCI3), : 26.2
(CH2); 26.4 (CH2); 27.0 (CH2); 27.3 (CH2); 27.6 (CH2); 30.47
(CH2); 30.48 (CH2); 33.1 (CH2); 34.9 (CH2); 38.0 (CH); 38.4
(CH); 40.3 (CH); 114.7 (CH); 128.1; 130.3 (C); 137.9 (С);
138.6 (С); 143.1 (C).
X-ray diffraction study of compound 6 was carried out on
a Bruker D8 Quest diffractometer (- and -scan technique,
МоК radiation,  = 0.71073 Å, T = 100 K). The experimental
sets of intensities were integrated using the SAINT program.28
The structure was solved by the direct method and refined by the
full-matrix least squares method with anisotropic displacement
parameters based on F2 for non-hydrogen atoms. Hydrogen
hkl
atoms were positioned geometrically and refined isotropically.
The structure calculations were performed using the SHELXTL
software package.29 Absorption was taken into account using the
SADABS program.30 In the crystal of compound 6, the cyclo-
hexyl substituents are disordered, in molecule A all three cyclo-
hexyl substituents (only two in molecule B) were refined over
two positions. The crystallographic data and parameters of the
X-ray diffraction experiment for compound 6 are given in Tables 2
and 3. Structure 6 is registered at the Cambridge Crystallographic
Data Center (CCDC 2014585) and is available at ccdc.cam.
ac.uk/getstructures.
3,6-Dicyclohexylcyclohexa-3,5-diene-1,2-dione (4). Brown
green crystals, m.p. 129—131 С. Found (%): C, 79.61; H, 9.43.
C18H24O2. Calculated (%): C, 79.37; H, 8.88. IR, /cm–1
:
1674 (s), 1668 (s), 1652 (s), 1464 (s), 1451 (s), 1396 (s), 1378 (s),
1357 (m), 1345 (m), 1325 (m), 1300 (m), 1268 (m), 1233 (m),
1180 (m), 1154 (w), 1134 (w), 1108 (w), 1076 (w), 1052 (w),
1027 (w), 1003 (w), 953 (m), 920 (w), 905 (w), 885 (m), 864 (m),
855 (w), 845 (w), 833 (w), 786 (w), 721 (m), 669 (w), 621 (m),
570 (w), 527 (w), 490 (w), 468 (w). 1H NMR (CDCl3),
This work was financially supported by the Russian
Science Foundation (Project No. 19-13-00142). The stud-
ies were carried out using the equipment of the Center for
Collective Use "Analytical Center of the IMCh RAS" at
the G. A. Razuvaev Institute of Organometallic Chemistry

Alkylation of catechol
Russ. Chem. Bull., Int. Ed., Vol. 69, No. 12, December, 2020
2389
17. G. A. Abakumov, V. K. Cherkasov, T. N. Kocherova, N. O.
Druzhkov, Yu. A. Kurskii, M. P. Bubnov, G. K. Fukin,
L. G. Abakumova, Russ. Chem. Bull., 2007, 56, 1849; DOI:
10.1007/s11172-007-0287-6.
18. G. K. Fukin, A. V. Cherkasov, M. P. Shurygina, N. O.
Druzhkov, V. A. Kuropatov, S. A. Chesnokov, G. A. Aba-
kumov, Struct. Chem., 2010, 21, 607; DOI: 10.1007/s11224-
010-9590-1.
of the Russian Academy of Sciences and supported by the
Federal Target Program "Research and Development on
Priority Directions of Scientific and Technological Com-
plex of Russia for 2014—2020" (unique project identifier
RFMEFI62120X0040).
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Received July 9, 2020;
in revised form August 6, 2020;
accepted September 24, 2020
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