Synthesis of chiral azomethines from methyl l-3-phenylalaninate hydrochloride and substituted benzaldehydes of vanillin series

Article abstract of DOI:10.1134/S1070428011020084

A preparative procedure is developed for the synthesis of chiral azomethines from methyl L-3-phenylalaninate and substituted aldehydes of vanillin series.

Full text of DOI:10.1134/S1070428011020084

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 2, pp. 202206. Pleiades Publishing, Ltd., 2011.
Original Russian Text  E.A. Dikusar, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47, No. 2, pp. 213216.
Synthesis of Chiral Azomethines
from Methyl L-3-Phenylalaninate Hydrochloride
and Substituted Benzaldehydes of Vanillin Series
E. A. Dikusar
Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus, Minsk, 220072 Belarus
e-mail: dikusar@ifoch.bas-net.by
Received June 1, 2010
Abstract—A preparative procedure is developed for the synthesis of chiral azomethines from methyl L-3-
phenylalaninate and substituted aldehydes of vanillin series.
DOI: 10.1134/S1070428011020084
We formerly reported on the synthesis of azome-
thines from methyl L-valinate hydrochloride [1]. Many
azomethines exhibit a high antiviral, antitumor, and
antimicrobial action [2–4]. Methyl L-3-phenylalaninate
hydrochloride (I) may also serve as a convenient and
available synthon for the synthesis of chiral nitrogen
organic compounds [5].
ries IIa–IIt, IIIa–IIIl in the presence of sodium hydrogen
carbonate (at the stoichiometric reagents ratio 1 : 1 : 1)
led to the formation of new chiral alkylaromatic azome-
thines (Schiff bases) containing ether and ester groups
IVa–IVt, Va–Vl, VI, VIIa, VIIb. The condensation was
carried out in anhydrous methanol over 30–45 min. Chiral
alkylaromatic azomethines IVa–IVt, Va–Vl, VI, VIIa,
VIIb were obtained in preparative yields 77–90%.
The condensation of methyl L-3-phenylalaninate hy-
drochloride (I) with substituted aldehydes of vanillin se-
Azomethines IVa–IVt, Va–Vl, VI, VIIa, VIIb are
CHO
HC N CHCH2Ph
CO2Me
CO2Me
NaHCO3
NaCl
+
CHCH2Ph
.
R
R
NH2 HCl
R'
IIa_IIt, IIIa_IIIl
R'
IVa_IVt, Va_Vl
I
II, IV, R = H, R' = MeO (a); R = MeO, R' = HO (b), MeO (c), MeC(O)O (d), EtC(O)O (e), PrC(O)O (f), Me2CHC(O)O
(g), BuC(O)O (h), Me2CHCH2C(O)O (i), Me(CH2)8C(O)O (j), Me(CH2)16C(O)O (k), H2C=C(Me)C(O)O (l), C6H5CH(Me)
CH2C(O)O (m), C6H5C(O)O (n), 2,4-Cl2C6H3C(O)O (o), 4-BrC6H4C(O)O (p), 3-O2NC6H4C(O)O (q), MeOC(O)O (r),
EtOC(O)O (s), 1-AdC(O)O (t); III, V, R = EtO, R’= HO (a), MeO (b), MeC(O)O (c), EtC(O)O (d), PrC(O)O (e), Me2CHC(O)
O (f), BuC(O)O (g), Me2CHCH2C(O)O (h), 4-MeC6H4C(O)O (i), MeOC(O)O (j), EtOC(O)O (k), 1-AdC(O)O (l).
N
CHCH2Ph
CO2Me
HC
PhCH2HC N CH
CO2Me
X
VI, VIIa, VIIb
X = 4,4'-biphenyl (VI), ArOC(O)CH2CH2C(O)OAr [VII; Ar = C6H3(3-OMe) (a), C6H3(3-OEt) (b)].
202

SYNTHESIS OF CHIRAL AZOMETHINES
203
colorless or weakly colored thick oily fluids or crystal-
line substances, do not require an additional purification,
and are free of impurities of the initial compounds. The
structure of azomethines IVa–IVt, Va–Vl, VI, VIIa, VIIb
was proved by elemental analysis, IR, UV, 1H NMR, and
GC-MS methods. The purity of compounds obtained at-
tained 95±2%.
thin films or pellets with KBr, UV spectra, on a spec-
trophotometer Specord UV Vis from 1·10–4 M solutions
of compounds in methanol, 1H NMR spectra on a spec-
trometer Tesla BS-587A (100 MHz) from 5% solutions
in CDCl3 or (CD3)2SO4, internal reference TMS. The
specific rotation was measured on SM-2 instrument from
5% solutions of compounds in acetone. GC-MS measure-
ments were performed on a Hewlett Packard 5890/5972
instrument in the electron impact ionization mode, elec-
trons energy 70 eV, capillary column HP-5MS 30 m ×
0.25 mm, stationary phase 5% PhMe Silicone, 0.25 μm,
vaporizer temperature 250°C. The elemental analysis
was carried out on a CHNOS-analyzer Elementar Vario
EL-III, evaluation error 0.1%.
The following characteristic absorption bands were
observed in the IR spectra of azomethines IVa–IVt,
Va–Vl, VI, VIIa, VIIb (ν, cm–1): 3085–3000, 870–700
(CHarom), 2995–2825 (CHaliph), 1770–1738 (C=Oester ‘,
)
IVd–IVt, Vc–Vl, VIIa, VIIb, 1643–1633 (C=N),
1600–1418 (C=Carom), 1267–1025 (C–O). The presence
of the NO2 group in the compound IVq was proved by
the characteristic absorption bands in the IR spectrum in
the region 1531 and 1348 cm–1.
Initial methyl L-phenylalaninate hydrochloride (I)
was of “pure for analysis” grade, purity 98%, mp 161–
162°C, [α]D20 +32.1°. The vanillin and vanillal esters
IIa–IIt, IIIa–IIIl were prepared by procedures [7–10].
The UV spectra of compounds IVd–IVt, Vc–Vl, VIIa,
VIIb contain characteristic absorption maxima, λmax, nm
(ε): 204 (25000), 260 (9000), 303 (5000), 402 (200), due
to the presence in their molecules of the fragments of
methyl (E,S)-2-(3-alkoxy-4-acyloxybenzylideneamino)-
3-phenylpropionate.
Chiral alkylaromatic azomethines IVa–IVt, Va–Vl.
Amixture of 5 mmol of methyl L-phenylalaninate hydro-
chloride (I), 5 mmol of vanillin series aldehyde IIa–IIt,
IIIa–IIIl, and 5 mmol of sodium hydrogen carbonate in
30 ml of anhydrous methanol was boiled for 30–45 min.
The hot solution was filtered through a folded filter, the
solvent was removed in a vacuum. The residue was dis-
solved in 10 ml of anhydrous ethyl ether, the solution
was filtered through a folded filter, and the solvent was
removed in a vacuum. The final purification was per-
formed by column chromatography on neutral aluminum
oxide, 40–100 μm, II grade of Brockmann activity, eluent
dichloromethane.
In the 1H NMR spectra of azomethines IVa–IVt, Va–
Vl, VI, VIIa, VIIb the proton signals of the CH2 group ap-
pear as a multiplet in the region 2.90–3.60 ppm, the signals
of CHaliph, as a multipler in the region 4.05–4.65 ppm,
the signals of CO2Me, as a singlet at 3.74–3.76 ppm. In
the 1H NMR spectra of azomethines IVa–IVt, Vb, VIIa
the protons of MeO group give rise to a singlet in the
range 3.80–3.95 ppm, in the spectra of compounds Va–Vl,
VIIb the proton signals of EtO group are observed as
a triplet in the region 0.95–1.35 ppm (Me) and a quartet at
3.50–4.25 ppm (CH2). The signals of the aromatic protons
in the spectra of compounds IVa–IVt, Va–Vl, VI, VIIa,
VIIb appear in the range 6.75–7.75 ppm, the protons of
the azomethine group HC=N give rise to a singlet in the
region 7.80–7.83 ppm, characteristic of the azomethines
of (E)-configutation [6].
Methyl (E,S)-2-(4-methoxybenzylideneamino)-3-
phenylpropionate (IVa). Yield 87%, colorless crystals,
mp 78–79°C, [α]D20 –101.5°. Found, %: C 73.12; H 6.52;
N 4.35. M+ 297. C18H19NO3. Calculated, %: C 72.71;
H 6.44; N 4.71. M 297.35.
Methyl (E,S)-2-(4-hydroxy-3-methoxybenzylidene-
amino)-3-phenylpropionate (IVb). Yield 77%, color-
less crystals, mp 167–168°C, [α]D20 –103.7°. Found, %:
C 69.41; H 6.28; N 4.05. M+ 313. C18H19NO4. Calculated,
%: C 68.99; H 6.11; N 4.47. M 313.35.
In the IR, UV, and 1H NMR spectra of azomethines
IVa–IVt, Va–Vl, VI, VIIa, VIIb the absorption bands
and proton signals are observed confirming the presence
of the corresponding fragment of ester groups.
Methyl (E,S)-2-(3,4-dimethoxybenzylideneamino)-
3-phenylpropionate (IVc). Yield 91%, colorless
20
fluid,
d
1.2488, nD20 1.5640, [α]D20 –105.5°. Found, %:
EXPERIMENTAL
20
C 69.98; H 6.59; N 3.94. M+ 327. C19H21NO4. Calculated,
%: C 69.71; H 6.47; N 4.28. M 327.37.
IR spectra of compounds were recorded on an IR
Fourier spectrophotometer Nicolet Protégé-460 from
Methyl (E,S)-2-(4-acetoxy-3-methoxybenzylidene-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 2 2011

DIKUSAR
204
ryloxy)benzylideneamino]-3-phenylpropionate
(IVm). Yield 90%, colorless crystals, mp 45–
46°C, [α]D20 –138.0°. Found, %: C 73.63; H 6.39;
N 2.84. M+ 459. C28H29NO5. Calculated, %: C 73.18;
H 6.36; N 3.05. M 459.53.
amino)-3-phenylpropionate (IVd). Yield 85%, colorless
crystals, mp 28–29°C, [α]D20 –112.6o. Found, %: C 67.86;
H 6.20; N 3.66. M+ 355. C20H21NO5. Calculated, %:
C 67.59; H 5.96; N 3.94. M 355.38.
Methyl (E,S)-2-(3-methoxy-4-propionyloxy-ben-
zylidene-amino)-3-phenylpropionate (IVe). Yield 86%,
colorless crystals, mp 35–36°C, [α]D20 –119.8°. Found, %:
C 68.81; H 6.37; N 3.60. M+ 369. C21H23NO5. Calculated,
%: C 68.28; H 6.28; N 3.79. M 369.41.
Methyl (E,S)-2-(4-benzoyloxy-3-methoxybenzyl-
idene-amino)-3-phenylpropionate (IVn). Yield 86%,
colorless fluid, d2200 1.2512, nD20 1.5720, [α]D20 –132.4°.
Found, %: C 72.27; H 5.68; N 3.08. M+ 417. C25H23NO5.
Calculated, %: C 71.93; H 5.55; N 3.36. M 417.45.
Methyl (E,S)-2-(4-butyryloxy-3-methoxybenzyl-
idene-amino)-3-phenylpropionate (IVf). Yield 88%,
colorless crystals, mp 31–32°C, [α]D20 –127.2°. Found, %:
C 69.26; H 6.82; N 3.19. M+ 383. C22H25NO5. Calculated,
%: C 68.91; H 6.57; N 3.65. M 383.44.
Methyl (E,S)-2-[4-(2,4-dichlorobenzoyloxy)-3-me-
thoxybenzylideneamino]-3-phenylpropionate (IVo).
20
Yield 87%, colorless fluid,
d
1.2684, nD20 1.5855, [α]
20
20 –144.1°. Found, %: C 62.18; H 4.49; Cl 14.21; N 2.52.
D
M+ 486. C25H21Cl2NO5. Calculated, %: C 61.74; H 4.35;
Cl 14.58; N 2.88. M 486.34.
Methyl (E,S)-2-(4-isobutyryloxy-3-methoxy-ben-
zylidene-amino)-3-phenylpropionate (IVg). Yield 87%,
20
colorless fluid, d 1.2124, nD20 1.5415, [α]D20 –132.9°.
Methyl (E,S)-2-[4-(4-bromobenzoyloxy)-3-
20
Found, %: C 69.33; H 6.68; N 3.46. M+ 383. C22H25NO5.
Calculated, %: C 68.91; H 6.57; N 3.65. M 383.44.
methoxy-benzylideneamino]-3-phenylpropio-
20
nate (IVp). Yield 85%, colorless fluid,
d
1.2707,
20
nD20 1.5960, [α]D20 –139.3°. Found, %: C 60.83; H 4.67;
Br 15.77; N 2.45. M+ 496. C25H22BrNO5. Calculated, %:
C 60.50; H 4.47; Br 16.10; N 2.82. M 496.07.
Methyl (E,S)-2-(4-valeroyloxy-3-methoxybenzyl-
idene-amino)-3-phenylpropionate (IVh). Yield 85%,
colorless crystals, mp 87–88°C, [α]D20 –130.6°. Found, %:
C 69.92; H 7.03; N 3.25. M+ 397. C23H27NO5. Calculated,
%: C 69.50; H 6.85; N 3.52. M 397.46.
Methyl (E,S)-2-[3-methoxy-4-(3-nitrobenzoyloxy)
benzylideneamino]-3-phenylpropionate (IVq). Yield
82%, colorless crystals, mp 132–133°C, [α]D20 –151.2°.
Found, %: C 65.23; H 4.99; N 5.78. M+ 462. C25H22N2O7.
Calculated, %: C 64.93; H 4.80; N 6.06. M 462.45.
Methyl (E,S)-2-(4-isovaleroyloxy-3-methoxyben-
zylidene-amino)-3-phenylpropionate (IVi). Yield 87%,
colorless crystals, mp 162–163°C, [α]D20 –134.2°. Found,
%: C 69.87; H 6.99; N 3.20. M+ 397. C23H27NO5. Calcu-
lated, %: C 69.50; H 6.85; N 3.52. M 397.46.
Methyl (E,S)-2-(4-methoxycarbonyl-3-me-
thoxybenzylidene-amino)-3-phenylpropionate
20
(IVr). Yield 82%, colorless fluid,
d
1.2288, nD20 1.5485,
Methyl (E,S)-2-(4-caprinoyloxy-3-methoxybenzyl-
iden-eamino)-3-phenylpropionate (IVj). Yield 89%,
colorless crystals, mp 64–65°C, [α]D20 –135.7°. Found, %:
C 72.26; H 8.16; N 2.76. M+ 467. C28H37NO5. Calculated,
%: C 71.92; H 7.98; N 3.00. M 467.60.
20
[α]D20 –115.6°. Found, %: C 65.21; H 5.82; N 3.56.
M+ 371. C20H21NO6. Calculated, %: C 64.68; H 5.70;
N 3.77. M 371.38.
Methyl (E,S)-2-(3-methoxy-4-ethoxycarbonyl-
oxybenzylideneamino)-3-phenylpropionate
Methyl (E,S)-2-(3-methoxy-4-stearoyloxy-benzyl-
idene-amino)-3-phenylpropionate (IVk). Yield 91%,
colorless crystals, mp 52–53°C, [α]D20 –139.2°. Found, %:
C 74.86; H 9.32; N 2.18. M+ 579. C36H53NO5. Calculated,
%: C 74.57; H 9.21; N 2.42. M 579.81.
20
(IVs). Yield 83%, colorless fluid,
d
1.2230,
20
nD20 1.5460, [α]D20 –117.1°. Found, %: C 65.89; H 6.24;
N 3.18. M+ 385. C21H23NO6. Calculated, %: C 65.44;
H 6.02; N 3.63. M 385.41.
Methyl (E,S)-2-(4-methacryloyloxy-3-me-
Methyl (E,S)-2-[4-(1-adamantylmethanoyloxy)-
3-methoxybenzylideneamino]-3-phenylpropio-
nate (IVt). Yield 87%, colorless crystals, mp 66–67°C,
[α]D20 –147.0°. Found, %: C 73.72; H 7.17; N 2.63. M+
475. C29H33NO5. Calculated, %: C 73.24; H 6.99; N 2.95.
M 475.58.
thoxy-benzylideneamino)-3-phenylpropionate
20
(IVl). Yield 88%, colorless fluid,
d
1.2278,
20
nD20 1.5605, [α]D20 –126.5°. Found, %: C 69.51; H 6.24;
N 3.29. M+ 381. C22H23NO5. Calculated, %: C 69.28;
H 6.08; N 3.67. M 381.42.
Methyl (E,S)-2-[3-methoxy-4-(3-phenylbuty-
Methyl (E,S)-2-(4-hydroxy-3-ethoxybenzylidene-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 2 2011

SYNTHESIS OF CHIRAL AZOMETHINES
205
20
amino)-3-phenylpropionate (Va). Yield 78%, color-
less crystals, mp 143–144°C, [α]D20 –102.8°. Found, %:
C 70.08; H 6.54; N 3.99. M+ 327. C19H21NO4. Calculated,
%: C 69.71; H 6.47; N 4.28. M 327.37.
Yield 84%, colorless fluid,
d
1.2208, nD20 1.5500,
20
[α]D20 –110.7°. Found, %: C 65.80; H 6.18; N 3.47. M+
385. C21H23NO6. Calculated, %: C 65.44; H 6.02; N
3.63. M 385.41.
Methyl (E,S)-2-(4-ethoxycarbonyloxy-3-
Methyl (E,S)-2-(4-methoxy-3-ethoxybenzylidene-
ethoxybenzylidene-amino)-3-phenylpropionate
amino)-3-phenylpropionate (Vb). Yield 80%, colorless
20
20
fluid,
d
1.2414, nD20 1.5605, [α]D20 –108.6°. Found, %:
(Vk). Yield 83%, colorless fluid,
d
1.2164,
20
20
nD20 1.5430, [α]D20 –108.4°. Found, %: C 66.47; H 6.52;
N 3.24. M+ 399. C22H25NO6. Calculated, %: C 66.15;
H 6.31; N 3.51. M 399.44.
C 70.73; H 6.85; N 3.87. M+ 341. C20H23NO4. Calculated,
%: C 70.36; H 6.79; N 4.10. M 341.40.
Methyl (E,S)-2-(4-acetoxy-3-ethoxybenzylidene-
amino)-3-phenylpropionate (Vc). Yield 88%, colorless
crystals, mp 76–77°C, [α]D20 –110.2°. Found, %: C 68.53;
H 6.34; N 3.55. M+ 369. C21H23NO5. Calculated, %:
C 68.28; H 6.28; N 3.79. M 369.41.
Methyl (E,S)-2-[4-(1-adamantylmethanoyl-
oxy)-3-ethoxybenzylideneamino]-3-phenylpropi-
20
onate (Vl). Yield 84%, colorless fluid,
d
1.2326,
20
nD20 1.5560, [α]D20 –125.2°. Found, %: C 73.82; H 7.37;
N 2.80. M+ 489. C30H35NO5. Calculated, %: C 73.59;
H 7.21; N 2.86. M 489.60.
Methyl (E,S)-2-(4-propionyloxy-3-ethoxybenzyl-
idene-amino)-3-phenylpropionate (Vd). Yield 85%,
Bisazomethines VI, VIIa, VIIb were obtained and
isolated analogously to compounds IVa–IVt, Va–Vl.
A mixture of 10 mmol of compound I, 5 mmol of an
appropriate dialdehyde (biphenyl-4,4'-dicarbaldehyde,
succinate of vanillin or vanillal), and 10 mmol of sodium
hydrogen carbonate in 50 ml of anhydrous methanol was
boiled for 45 min.
20
colorless fluid,
d
1.2110, nD20 1.5470, [α]D20 –112.5°.
20
Found, %: C 69.18; H 6.73; N 3.40. M+ 383. C22H25NO5.
Calculated, %: C 68.91; H 6.57; N 3.65. M 383.44.
Methyl (E,S)-2-(4-butyryloxy-3-ethoxybenzyli-
dene-amino)-3-phenylpropionate (Ve). Yield 89%,
colorless fluid, d2200 1.1956, nD20 1.5505, [α]D20 –100.4°.
Found, %: C 69.67; H 7.05; N 3.19. M+ 397. C23H27NO5.
Calculated, %: C 69.50; H 6.85; N 3.52. M 397.46.
Dimethyl 2,2'-{biphenyl-4,4'-diylbis[(E)-
methylidenenitrilo]}di[(S)-3-phenylpropionate]
Methyl (E,S)-2-(4-isobutyryloxy-3-ethoxybenzyl-
20
(VI). Yield 85%, colorless fluid,
d
1.2570,
20
idene-amino)-3-phenylpropionate (Vf). Yield 89%,
nD20 1.6025, [α]D20 –188.3°. Found, %: C 76.93; H 6.12;
N 5.29. M+ 532. C34H32N2O4. Calculated, %: C 76.67;
H 6.06; N 5.26. M 532.63.
20
colorless fluid,
d
1.1940, nD20 1.5435, [α]D20 –87.0°.
20
Found, %: C 69.77; H 6.94; N 3.32. M+ 397. C23H27NO5.
Calculated, %: C 69.50; H 6.85; N 3.52. M 397.46.
Bis{3-methoxy-4-[(E,S)-(1-methoxycarbonyl-
Methyl (E,S)-2-(4-valeroyloxy-3-ethoxybenzyli-
dene-amino)-3-phenylpropionate (Vg). Yield 85%,
colorless crystals, mp 67–68°C, [α]D20 –93.3°. Found, %:
C 70.26; H 7.30; N 3.08. M+ 411. C24H29NO5. Calculated,
%: C 70.05; H 7.10; N 3.40. M 411.49.
2-phenyl)ethyliminomethyl]phenyl}butanedio-
20
ate (VIIa). Yield 87%, colorless fluid,
d
1.2428,
20
nD201.5585, [α]D20 –174.5°. Found, %: C 74.87; H 6.07;
N 4.11. M+ 644. C40H40N2O6. Calculated, %: C 74.51;
H 6.25; N 4.34. M 644.76.
Methyl (E,S)-2-(4-isovaleroyloxy-3-ethoxybenzyl-
idene-amino)-3-phenylpropionate (Vh). Yield 83%,
colorless crystals, mp 42–43°C, [α]D20 –99.6°. Found, %:
C 70.38; H 7.24; N 3.17. M+ 411. C24H29NO5. Calculated,
%: C 70.05; H 7.10; N 3.40. M 411.49.
Bis{4-[(E,S)-(1-methoxycarbonyl-2-phenyl)
ethyl-iminomethyl]-3-ethoxyphenyl}butanedio-
20
ate (VIIb). Yield 85%, colorless fluid,
d
1.2342,
20
nD20 1.5515, [α]D20 –166.2°. Found, %: C 75.23; H 6.68;
N 3.76. M+ 672. C42H44N2O6. Calculated, %: C 74.98;
H 6.59; N 4.16. M 672.81.
Methyl (E,S)-2-[4-(4-methylbenzoyloxy)-3-ethoxy-
benzylidene-amino]-3-phenylpropionate (Vi). Yield
89%, colorless crystals, mp 75–76°C, [α]D20 –116.4°.
Found, %: C 73.14; H 6.22; N 2.87. M+ 445. C27H27NO5.
Calculated, %: C 72.79; H 6.11; N 3.14. M 445.51.
REFERENCES
1. Dikusar, E.A., Potkin, V.I., and Zhukovskaya, N.A., Zh.
Org. Khim., 2010, vol. 46, p. 655.
Methyl (E,S)-2-(4-methoxycarbonyloxy-3-eth-
2. Chimirri, A., Gitto, R., Grasso, S., Monforte, A.-M., and
oxybenzylidene-amino)-3-phenylpropionate (Vj).
Zappala, M., Farmaco., 1994, vol. 49, p. 649.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 2 2011

DIKUSAR
206
3. Isaev, S.D., Novoselov, E.F., and Yurchenko, A.G., Zh. Org.
Khim., 1985, vol. 21, p. 103.
7. Dikusar, E.A., Vyglazov, O.G., Moiseichuk, K.L., Zhukovs-
kaya, N.A., and Kozlov, N.G., Zh. Prikl. Khim., 2005, vol.
78, p. 122.
4. Trivedi, S.D., Kubawat, H.T., and Parekh, H.H., J. Indian
Chem. Soc., 2002, p. 282.
8. Dikusar, E.A. and Kozlov, N.G., Khim. Polim. Soedin.,
2005, p. 74.
5. Puchina, G.R., Cand. Sci. (Chem.) Dissertation, Ufa, 2007.
9. Dikusar, E.A., Kozlov, N.G. Zh. Org. Khim., 2005, vol. 41,
6. Dyer, J.R., Applications of Absorption Spectroscopy of
Organic Compounds, Englewood Cliffs: Prentice Hall,
1965.
p. 1015.
10. Dikusar, E.A., Zh. Prikl. Khim., 2006, vol. 79, p. 1043.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 2 2011