Reactions of 4-acylresorcinol derivatives with 3,5-di-tert-butyl-4- hydroxybenzyl acetate

Article abstract of DOI:10.1007/s11172-006-0395-8

Reactions of hydroxyphenylcarbonyl derivatives with 3,5-di-tert-butyl-4- hydroxybenzyl acetate under mild conditions gave novel functionalized diarylmethanes. Springer Science+Business Media, Inc. 2006.

Full text of DOI:10.1007/s11172-006-0395-8

Russian Chemical Bulletin, International Edition, Vol. 55, No. 7, pp. 1171—1176, July, 2006
1171
Reactions of 4ꢀacylresorcinol derivatives
with 3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl acetate
E. M. Kasymova,a A. R. Burilov,a L. I. Vagapova,a N. A. Mukmeneva,b S. V. Bukharov,b G. N. Nugumanova,b
D. B. Krivolapov,a M. A. Pudovik,aꢀ I. A. Litvinov,a and A. I. Konovalova
aA. E. Arbuzov Institute of Organic and Physical Chemistry,
Kazan Research Center of the Russian Academy of Sciences,
8 ul. Akad. Arbuzova, 420088 Kazan, Russian Federation.
Fax: +7 (843 2) 75 2253. Eꢀmail: pudovik@iopc.knc.ru
bKazan State Technological University,
68 ul. K. Marksa, 420015 Kazan, Russian Federation.
Reactions of hydroxyphenylcarbonyl derivatives with 3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl
acetate under mild conditions gave novel functionalized diarylmethanes.
Key words: Cꢀbenzylation, diarylmethanes, resorcinols, arenes, carbonyl compounds, Xꢀray
diffraction analysis.
Scheme 1
Researchers are giving much attention to problems of
the synthesis, structures, and properties of phenol stabiꢀ
lizers of polymeric materials. Relevant data, including
those on their efficiencies and stabilization mechanism,
have been reported in some monographs.1—7 2ꢀHydroxyꢀ
phenylcarbonyl compounds belong to a commonly used
class of light stabilizers of polymers.8 Introduction of steriꢀ
cally hindered phenolic fragments (e.g., 3,5ꢀdiꢀtertꢀbuꢀ
tylꢀ4ꢀhydroxybenzyl group) affords polyfunctional stabiꢀ
lizers that function as both UV absorbers and scavengers
for peroxide radicals.9 However, a search for efficient
benzylating agents for selective introduction of 3,5ꢀdiꢀ
tertꢀbutylꢀ4ꢀhydroxybenzyl fragments with the aim of obꢀ
taining novel sterically hindered phenol derivatives reꢀ
mains of topical interest. Recently, we have developed a
simple and feasible method for the synthesis of 3,5ꢀdiꢀ
tertꢀbutylꢀ4ꢀhydroxybenzyl acetate (1) and showed some
of its synthetic potentialities.10
Here we studied acetate 1 as a possible reagent for the
benzylation of 2ꢀhydroxyꢀ4ꢀmethoxybenzophenone (2a)
and 2ꢀhydroxyꢀ4ꢀoctyloxybenzophenone (2b) (Scheme 1).
Reactions catalyzed by acetic, formic, or perchloric acid
under mild conditions (1.5 h, 40 or 50 °C) gave 5ꢀbenꢀ
zylated benzophenones 3a,b in high yields.
R = Me (2a, 3a), C8H17 (2b, 3b)
The 1H NMR spectra of products 3a,b show no signal
for the H(2) proton, which is present in the spectra of the
starting compounds 2a,b. The signal for the OH proton at
δ 12.9 is retained, while the signals for the H(1) and
hydroxybenzaldehyde (4b) gave 3,5ꢀdibenzylated prodꢀ
ucts (Scheme 2). Earlier,11 it has been assumed that such
reactions involve simultaneous benzylation of position 5
of the aromatic ring and of the OH group at the C(4) atom.
It should be noted that dibenzylation products 5a,b
were detected in the reaction mixture even when the reꢀ
agents had been used in an equimolar ratio. Their strucꢀ
tures were proven by 1H and 13C NMR spectroscopy. The
1
H(4) protons appear as singlets. The H NMR data unꢀ
ambiguously confirm our conclusion about the structures
of the final products. Analogous reactions of benzyl acꢀ
etate 1 with 2,4ꢀdihydroxybenzophenone (4a) and 2,4ꢀdiꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1128—1133, July, 2006.
1066ꢀ5285/06/5507ꢀ1171 © 2006 Springer Science+Business Media, Inc.

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Kasymova et al.
Scheme 2
ments C(8)—C(13) and C(24)—C(29) are 121.0(3)° and
103.3(3)°, respectively. The angle between the
C(8)—C(13) and C(24)—C(29) planes is 17.8(4)°.
In the crystal of complex 5b•HCO2H, intermolecular
OH...O hydrogen bonds unite molecules of compound 5b
and solvate molecules of formic acid into an infinite zigꢀ
zag chain aligned with the axis 0x (Fig. 2). The hydrogen
bonds parameters for the fragment O(1)—H(1)...O(43´)
(x, 1 – y, 1/2 + z) are O(1)—H(1) 0.82 Å, H(1)...O(43)
2.06 Å, O(1)...O(43) 2.78(1) Å, and O(1)—H(1)...O(43)
148° and for the fragment O(41)—H(41)...O(15) are
O(41)—H(41) 0.82 Å, O(41)...H(41) 2.02 Å,
O(41)...O(15) 2.83(2) Å, and O(41)—H(41)...O(15) 175°.
A reaction of benzylic acetate 1 with 2,4ꢀdihydroxyꢀ
benzophenone (4a) in the presence of triethylamine gave
3ꢀ(3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl)ꢀ2,4ꢀdihydroxyꢀ
benzophenone (6) (Scheme 3). Here triethylamine acts as
a base with respect to both benzophenone 4a and benzylic
acetate 1, thus providing the formation of 2,6ꢀdiꢀtertꢀ
butylꢀpꢀquinone methide (7) from the latter.12 Comꢀ
pound 6 is an adduct of anion 8 and pꢀquinone methide 7.
Structure 6 was confirmed by 1H and 13C NMR specꢀ
troscopy and Xꢀray diffraction analysis (Fig. 3, Table 1).
The asymmetric part of the crystal of compound 6
contains two independent molecules A and B. It should
be noted that the geometrical parameters of molecules A
R = Ph (4a, 5a), H (4b, 5b)
crystal structure of compound 5b was determined by Xꢀray
diffraction analysis (Fig. 1, Table 1).
The asymmetric part of the unit cell contains a molꢀ
ecule of compound 5b and a molecule of formic acid.
The aromatic fragments have standard geometries. The
angles between the plane of the central aromatic fragꢀ
ment C(1)—C(6) and the terminal aromatic fragꢀ
C(21)
C(20)
C(37)
C(35)
C(19)
C(18)
C(34)
C(36)
C(12)
O(1)
C(29)
C(28)
O(11)
C(13)
C(8)
C(24)
C(11)
C(10)
C(23)
O(27)
C(1)
C(27)
C(6)
C(7)
C(15)
C(26)
C(25)
C(9)
C(14)
C(2)
C(3)
C(5)
C(32)
C(16)
C(17)
C(30)
C(31)
C(4)
C(22)
C(33)
O(3)
O(15)
O(41)
O(43)
C(42)
Fig. 1. Crystal geometry for the complex of compound 5b with formic acid.

Reactions of 4ꢀacylresorcinol derivatives
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 7, July, 2006
1173
Table 1. Crystallographic parameters of compounds 5b and 6
and a summary of data collection
Parameter
5b
6
Color, habitus
Colorless prismatic
Molecular formula
Crystal system
Space group
Unit cell parameters:2
C37H50O5•CO2H2
Orthorhombic
Pbcn
C28H32O4
Monoclinic
P21/n
a/Å
b/Å
c/Å
32.748(10)
11.33(2)
19.171(10)
—
7115(13)
8
8.473(2)
15.54(6)
38.03(10)
95.2(4)
4986(24)
8
β/deg
V/Å3
Z
Fig. 2. Hydrogen bonds in the crystal of complex 5b•HCO2H.
Molecular mass
ρ
620.80
1.159
432.54
1.152
calc/g cm–3
Absorption coefficient,
Scheme 3
µCu/cm–1
6.27
2688
6.02
1856
F(000)
Radiation
CuKα
λ/Å
1.54184
θ range
2.7 < θ < 55.06
4.67 < θ < 59.95
Scan mode
ωꢀScan mode
Ranges of hkl indices
0 < h < 34,
–12 < k < 12,
–163 < l < 20
10234
0 < h < 6,
17 < k < 17,
–42 < l < 42
5940
Number of measured
reflections
Number of observed
reflections with I > 2σ(I )
Final residuals
R
Rw
GOOF
1357
877
0.064
0.171
0.939
0.04
0.088
0.161
1.522
0
∆/σ
Number of reflections
used in the refinement
Number of parameters
refined
4459
400
5940
298
Note. Standard (two orientation checking and three intensity
control) reflections were measured after every 200 reflections.
Absorption correction was not applied.
and B are equal to within the experimental error. The
aromatic fragments have standard bond lengths and angles,
as in the crystal of compound 5b. In molecule A, the
angles between the plane of the central aromatic fragment
C(16A)—C(21A) and the terminal aromatic fragments
C(2A)—C(7A) and C(22A)—C(28A) are 101.3(5)°
and 125.5(5)°, respectively. The angle between the
C(2A)—C(7A) and C(22A)—C(28A) planes is 53.8(5)°.
In molecule B, the angles between the plane of the central
aromatic fragment C(16B)—C(21B) and the terminal aroꢀ
matic fragments C(2B)—C(7B) and C(22B)—C(28B)
are 100.8(5)° and 124.2(5)°, respectively. The angle beꢀ
tween the C(2B)—C(7B) and C(22B)—C(28B) planes
is 54.1(5)°.
Intraꢀ and intermolecular OH...O hydrogen bonds
were detected in the crystal of compound 6 (Fig. 4). The
intramolecular hydrogen bond O(17A)—H(17A)...O(22A)
(O(17A)—H(17A) 0.82 Å, H(17A)...O(22A) 1.80 Å,
O(17A)...O(22A) 2.53(2) Å, O(17A)—H(17A)...O(22A)
145°) closes a sixꢀmembered ring. The parameters
of the intermolecular hydrogen bonds are as folꢀ
lows: O(21A)—H(21A) 0.82 Å, H(21A)...O(22A)

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Kasymova et al.
O(21A)
C(2A)
C(15A)
C(6A)
C(21A)
C(20A)
C(12A)
O(5A)
C(7A)
C(19A)
C(16A)
C(14A)
C(5A)
C(4A)
C(8A)
C(1A)
C(18A)
C(28A)
C(27A)
C(26A)
C(17A)
O(17A)
C(11A)
C(22A)
C(3A)
C(9A)
C(11B)
C(23A)
O(22A)
C(25A)
C(24A)
C(9B)
O(22B)
C(23B)
C(8B)
C(4B)
O(17B)
C(22B)
C(17B)
C(24B)
C(25B)
C(10B)
C(3B)
C(1B)
O(5B)
C(14B)
C(5B)
C(6B)
C(7B)
C(26B)
C(27B)
C(28B)
C(18B)
C(19B)
C(2B)
C(12B)
C(15B)
C(16B)
C(21B)
C(13B)
C(20B)
O(21B)
Fig. 3. Geometry of the independent molecules in the crystal of compound 6.
2.04 Å, O(21A)...O(22A) 2.79(2) Å, and
parameters of the interaction are as follows: distance beꢀ
tween the C(16A)—C(21A) and C(16B)—C(21B) planes
(3/2 – x, 1/2 + y, 1/2 – z) is 3.550 Å and the angle
between the planes is 1°.
O(21A)—H(21A)...O(22A) 151° in the fragment
O(21A)—H(21A)...O(22A) (1/2 – x, 1/2 + y, 1/2 – z)
and O(21B)—H(21B) 0.96 Å, H(21B)...O(22B)
1.84
Å,
O(21B)...O(22B)
2.71(2)
Å,
and
To elucidate the causes of the regioselectivity of this
O(21B)—H(21B)...O(22B) 150° in the fragment
O(21B)—H(21B)...O(22B) (1/2 – x, –1/2 + y, 1/2 – z).
The resulting parallel infinite zigzag chains are aligned
with the axis 0b and linked by the π...πꢀinteractions of the
aromatic rings. Interestingly, the chains consist of molꢀ
ecules of one type (A or B).
reaction, additional investigation is required.
The acidꢀcatalyzed benzylation of 2,4ꢀdihydroxyꢀ
phenylcarbonyl compounds is a reversible process. This is
evident from a structural change in compound 6 upon its
heating in acetone in the presence of perchloric acid (see
1
Scheme 3). The H NMR spectrum of the reaction mixꢀ
The π...πꢀinteractions give rise to molecular stacks in
the crystal, which are parallel to the axis 0a (Fig. 5). The
ture contains a signal for the methylene protons at δ 3.76
characteristic of a 3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl subꢀ
Fig. 4. Hydrogen bonds in the crystal of compound 6 (hydrogen atoms are omitted).

Reactions of 4ꢀacylresorcinol derivatives
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 7, July, 2006
1175
Fig. 5. Crystal packing of compound 6.
acetate (1)10 (2.78 g, 0.01 mol) in AcOH (20 mL). The reaction
mixture was kept at 50 °C for 90 min and poured into water. The
precipitate that formed was filtered off, washed with water, dried,
and crystallized from hexane. The yield of compound 3a was
3.17 g (71%), m.p. 136 °C. Found (%): C, 78.26; H, 7.70.
C29H34O4. Calculated (%): C, 78.00; H, 7.67. 1H NMR, δ: 1.38
(s, 18 H, CMe3); 3.71 (s, 2 H, CH2); 3.90 (s, 3 H, MeO); 5.04 (s,
1 H, OH); 6.50 (s, 1 H, H(1)); 6.94 (s, 2 H, H(3)); 7.21 (s, 1 H,
H(4)); 7.35—7.55 (m, 5 H, ArH); 12.68 (s, 1 H, OH...O).
13C NMR (CDCl3, 20 °C), δ: 30.3 (CMe3); 34.2 (CMe3); 34.8
(ArCH2Ar); 55.7 (MeO); 199.8 (C=O); 99.2; 112.3; 122.3; 125.3;
128.1; 128.7; 130.7; 131.3; 134.6; 135.7; 138.3; 151.9; 164.0;
165.1 (Carom).
5ꢀ(3,5ꢀDiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl)ꢀ2ꢀhydroxyꢀ4ꢀoctylꢀ
oxybenzophenone (3b). Two to three drops of 72% HClO4 were
added to a solution of 2ꢀhydroxyꢀ4ꢀoctyloxybenzophenone (2b)
(3.26 g, 0.01 mol) and ester 1 (2.78 g, 0.01 mol) in AcOH
(20 mL). The reaction mixture was kept at 40 °C for 1.5 h and
poured into water. The resulting oil was extracted with diethyl
ether, the extract was concentrated, and the residue was washed
with hexane. The yield of compound 3b was 3.81 g (70%), m.p.
103—104 °C. Found (%): C, 79.81; H, 8.36. C36H48O4. Calcuꢀ
lated (%): C, 79.37; H, 8.88. 1H NMR, δ: 0.89 (t, 3 H, CH3);
1.10—1.65 (m, 10 H, CH2); 1.39 (s, 18 H, CMe3); 1.74—1.95
(m, 2 H, CH2); 3.71 (s, 2 H, ArCH2Ar); 4.03 (t, 2 H, CH2O; J =
6.5 Hz); 5.03 (s, 1 H, OH); 6.47 (s, 1 H, H(1)); 6.95 (s, 2 H,
H(3)); 7.24 (s, 1 H, H(4)); 7.35—7.65 (m, 5 H, ArH); 12.69 (s,
1 H, OH...O).
3,5ꢀBis(3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl)ꢀ2,4ꢀdihydroxyꢀ
benzophenone (5a). Two to three drops of 72% HClO4 were
added to a solution of 2,4ꢀdihydroxybenzophenone (4a) (2.14 g,
0.01 mol) and ester 1 (5.56 g, 0.02 mol) in AcOH (40 mL). The
reaction mixture was kept at 50 °C for 1.5 h. The precipitate that
formed was filtered off, washed successively with AcOH and
water, and recrystallized from EtOH. The yield of compound 5a
was 5.26 g (81%), m.p. 166—167 °C. Found (%): C, 79.53;
H, 8.80. C43H54O5. Calculated (%): C, 79.35; H, 8.36. 1H NMR,
δ: 1.37, 1.39 (both s, 18 H each, CMe3); 3.74, 4.00 (both s,
2 H each, CH2); 5.08, 5.10 (both s, 1 H each, OH); 5.66 (s, 1 H,
OH(5)); 7.00 (s, 2 H, H(3)); 7.18 (s, 2 H, H(6)); 7.22 (s, 1 H,
H(4)); 7.35—7.67 (m, 5 H, Ph); 12.90 (s, 1 H, OH...O).
3,5ꢀBis(3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl)ꢀ2,4ꢀdihydroxyꢀ
benzaldehyde (5b). Ester 1 (2.64 g) was added to a solution of
2,4ꢀdihydroxybenzaldehyde (4b) (0.59 g) in acetone (9 mL) and
HCO2H (26 mL). The reaction mixture was heated with stirring
a
b
c
4.1
4.0
3.9
3.8
3.7
δ
Fig. 6. Fragments of the 1H NMR spectra (CDCl3) of comꢀ
pound 6 prior to (a) and after the treatment with perchloric
acid (b) and the H NMR spectrum of compound 5a (c).
1
stituent at the C(5) atom of the 2,4ꢀdihydroxybenzoꢀ
phenone system (Fig. 6, b). The data obtained suggest
easy ipsoꢀsubstitution in resorcinol derivatives, which
seems to lead, in our case, to compound 9. This circumꢀ
stance may be responsible for earlier reported13 easy deꢀ
composition of a calix[4]resorcinol system under the acꢀ
tion of benzyl acetate 1 in the presence of acids.
Experimental
1
H and 13C NMR spectra were recorded on a Bruker
WMꢀ250 instrument (250 (1H) and 62.9 MHz (13C)) in CDCl3
at 20 °C. Chemical shifts were measured with reference to sigꢀ
nals for residual protons (1H) and for a deuterated solvent (13C).
5ꢀ(3,5ꢀDiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl)ꢀ2ꢀhydroxyꢀ4ꢀ
methoxybenzophenone (3a). Two to three drops of 72% HClO4
were added to a solution of 2ꢀhydroxyꢀ4ꢀmethoxybenzophenone
(2a) (2.28 g, 0.01 mol) and 3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl

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Kasymova et al.
at 45 °C for 2 h. The crystals that formed were filtered off and
washed with pentane and water. The yield of compound 5b was
1.96 g (80% in respect to 4b), m.p. 92—94 °C. Found (%):
C, 77.52; H, 8.93. C37H50O5 Calculated (%): C, 77.36; H, 8.72.
1H NMR, δ: 1.36, 1.39 (both s, 18 H each, CMe3); 3.84, 4.02
(both s, 2 H each, CH2); 5.14 (s, 2 H, OH); 6.98 (s, 2 H(3));
7.12 (s, 2 H, H(6)); 7.17 (s, 1 H, H(4)); 9.68 (s, 1 H, CH(O));
11.65 (s, 1 H, OH...O).
ties and Efficiencies], Khimiya, Moscow, 1988, 247 (in
Russian).
2. V. V. Ershov, G. A. Nikiforov, and A. A. Volod´kin,
Prostranstvennoꢀzatrudnennye fenoly [Sterically Hindered
Phenols], Khimiya, Moscow, 1972 (in Russian).
3. N. M. Emanuel´ and A. L. Buchachenko, Khimicheskaya
fizika stareniya i stabilizatsii polimerov [Chemical Physics of
Polymer Aging and Stabilization], Nauka, Moscow, 1988 (in
Russian).
3ꢀ(3,5ꢀDiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl)ꢀ2,4ꢀdihydroxybenzoꢀ
phenone (6). A solution of ester 1 (2.78 g, 0.01 mol) in acetone
(30 mL) was added dropwise to a solution of 2,4ꢀdihydroxyꢀ
benzophenone (4a) (2.14 g, 0.01 mol) and triethylamine (2.8 mL,
0.02 mol) in acetone (10 mL). The reaction mixture was kept at
room temperature for a day, diluted with water, and neutralized
with AcOH. The precipitate that formed was washed with water
and recrystallized from ethanol. The yield of compound 6 was
2.16 g (50%), m.p. 223—225 °C. Found (%): C, 77.65; H, 7.30.
4. G. Scott, Development in Polymer Stabilization, Appl. Sci.
Publish., London, 1987.
5. N. Grassie and G. Scott, Polymer Degradation and Stabilizaꢀ
tion, Cambridge University Press, Cambridge, 1985.
6. V. Ya. Shlyapintokh, Fotokhimicheskie prevrashcheniya i
stabilizatsiya polimerov [Photochemical Transformations and
Stabilization of Polymers], Khimiya, Moscow, 1979 (in
Russian).
7. K. P. Piotrovskii and Z. N. Tarasova, Stroenie i stabilizatsiya
sinteticheskikh kauchukov i vulkanizatov [Structures and Staꢀ
bilization of Synthetic Caoutchoucs and Vulcanizates],
Khimiya, Moscow, 1980 (in Russian).
C
28H32O4. Calculated (%): C, 77.78; H, 7.41. 1H NMR, δ: 1.42
(s, 18 H, CMe3); 4.02 (s, 2 H, CH2); 5.11 (s, 1 H, OH); 5.55 (s,
1 H, H(5)); 6.31 (d, 1 H, H(2), J = 8.5 Hz); 7.21 (s, 2 H, H(3));
7.39 (d, 1 H, H(4), J = 8.5 Hz); 7.42—7.84 (m, 5 H, Ph).
13C NMR, δ: 28.2 (CH2); 30.4 (CMe3); 34.3 (CMe3); 103.8,
107.6, 107.8, 113.4, 115.5, 125.3, 128.2, 128.9, 129.8, 131.3,
133.6, 136.0, 136.4, 138.6, 152.4, 161.3, 164.0, 166.3 (Carom),
200.5 (C=O).
8. B. N. Gorbunov, Ya. A. Gurvich, and I. P. Maslova, Khimiya
i tekhnologiya stabilizatorov polimernykh materialov [Chemisꢀ
try and Technology of Stabilizers of Polymeric Materials],
Khimiya, Moscow, 1981 (in Russian).
Transformation of 3ꢀ(3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl)ꢀ2,4ꢀ
dihydroxybenzophenone (6) in an acidic medium. A drop of HClO4
was added to a solution of compound 6 (0.1 g, 2.3•10–4 mol) in
AcOH (5 mL) and acetone (2 mL). The mixture was heated at
50 °C for 2 h and poured into water. The precipitate was filtered
off, washed with water, and dried. The composition of the reacꢀ
9. J. A. Mock, Plast. Eng., 1982, 38, 35.
10. S. V. Bukharov, G. N. Nugumanova, N. A. Mukmeneva,
A. R. Burilov, E. M. Kasymova, M. A. Pudovik, and A. I.
Konovalov, Zh. Org. Khim., 2004, 40, 327 [Russ. J. Org.
Chem., 2004, 40 (Engl. Transl.)].
11. N. A. Mukmeneva, V. Kh. Kadyrova, S. V. Bukharov, and
G. N. Nugumanova, Zh. Obshch. Khim., 1996, 66, 1725
[Russ. J. Gen. Chem., 1996, 66 (Engl. Transl.)].
12. S. V. Bukharov, G. N. Nugumanova, and N. A. Mukmeneva,
Zh. Obshch. Khim., 2003, 73, 437 [Russ. J. Gen. Chem., 2003,
73 (Engl. Transl.)].
13. S. V. Bukharov, G. N. Nugumanova, N. A. Mukmeneva,
E. A. Teregulova, A. R. Burilov, M. A. Pudovik, I. L.
Nikolaeva, E. M. Kasymova, and A. I. Konovalov, Zh. Org.
Khim., 2003, 39, 735 [Russ. J. Org. Chem., 2003, 39 (Engl.
Transl.)].
1
tion mixture was monitored by H NMR spectroscopy.
Xꢀray diffraction analyses of compounds 5b and 6 (Table 1)
were performed on an EnrafꢀNonius CADꢀ4 automatic fourꢀ
circle diffractometer (λ(CuꢀKα), graphite monochromator,
ωꢀscan mode, θ < 74°). Three intensity control reflections showed
no decrease in intensity during the experiments. The structures
were solved by the direct method with the SIR program14 and
refined first isotropically and then anisotropically with the
SHELXꢀ97 program.15 The coordinates of the hydrogen atoms
were calculated from stereochemical criteria and refined in the
riding model. All calculations were performed with the MoLEN16
and WinGX programs.17 Figures were drawn and the hydrogen
bonds were analyzed with the PLATON program.18
14. A. Altomare, G. Cascarano, C. Giacovazzo, and D. Viterbo,
Acta Crystallogr., Sect. A, 1991, 47, 744.
15. G. M. Sheldrick, SHELXL97, Program for the Refinement of
Crystal Structure, Göttingen University, Göttingen, Gerꢀ
many, 1997.
Structural data have been deposited with the Cambridge
Crystallographic Data Center.
16. L. H. Straver and A. J. Schierbeek, MolEN. Structure Deterꢀ
mination System, Nonius B. V., 1994, 1, 180.
17. L. J. Farrugia, J. Appl. Crystallogr., 1999, 32, 837.
18. A. L. Spek, Acta Crystallogr., Sect. A, 1990, 46, 34.
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 05ꢀ03ꢀ
32136).
References
1. V. A. Roginskii, Fenol´nye antioksidanty. Reaktsionnaya
sposobnost´ i effektivnost´ [Phenol Antioxidants. Reactiviꢀ
Received January 25, 2006;
in revised form May 23, 2006