Synthesis of novel phosphorus-containing sterically hindered phenols by the reaction of diphenyl (3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidene) methylphosphonate with phenols

Article abstract of DOI:10.1007/s11172-011-0303-8

Diphenyl (3,5-di-tert-butyl-4-hydroxybenzyl)phosphonate was oxidized to the corresponding methylidenequinonoid derivative. The addition of phenols to the exocyclic double bond of this compound gave phosphonates with two phenol moieties.

Full text of DOI:10.1007/s11172-011-0303-8

Russian Chemical Bulletin, International Edition, Vol. 60, No. 10, pp. 1999—2002, October, 2011
1999
Synthesis of novel phosphorusꢀcontaining sterically hindered phenols
by the reaction of diphenyl (3,5ꢀdiꢀtertꢀbutylꢀ4ꢀoxocyclohexaꢀ2,5ꢀ
dienylidene)methylphosphonate with phenols
T. R. Shaekhov, E. M. Gibadullina, Yu. K. Voronina, V. V. Syakaev,
D. R. Sharafutdinova, A. R. Burilov, and M. A. Pudovik
A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences,
8 ul. Akad. Arbuzova, 420088 Kazan, Russian Federation.
Fax: +7 (843) 275 2253. Eꢀmail: elmirak@iopc.ru
Diphenyl (3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl)phosphonate was oxidized to the correspondꢀ
ing methylidenequinonoid derivative. The addition of phenols to the exocyclic double bond of
this compound gave phosphonates with two phenol moieties.
Key words: diphenyl (3,5ꢀdiꢀtertꢀbutylꢀ4ꢀoxocyclohexaꢀ2,5ꢀdienylidene)methylphosꢀ
phonate, oxidation, phenols, phosphonates.
Scheme 1
Derivatives of 2,6ꢀdiꢀtertꢀbutylphenols are efficient anꢀ
tioxidants, which are widely used as inhibitors of thermoꢀ
oxidative destruction of polymers, oils, fats, fuels, etc.
and as correctors of oxidant pathologies in living biologiꢀ
cal systems.1 The contemporary approach to the developꢀ
ment of new types of antioxidants is the design of hybrid
molecules containing combinations of several reaction
centers capable of inhibiting oxidation via various mechaꢀ
nisms.2,3 From this point of view it is interesting to obtain
structures containing simultaneously phosphorus atoms
and a fragment of sterically hindered phenol.4,5 Similar
structures can be synthesized using a phosphorusꢀconꢀ
taining derivative of 2,6ꢀdiꢀtertꢀbutylꢀ4ꢀmethylidenecycloꢀ
hexaꢀ2,5ꢀdienone.6—8 High reactivity of phosphorylated
methylidene quinones makes it possible to use them
successfully for synthesis of diverse sterically hindered
phenols, and in some cases the abovementioned approach
is most optimum.
bond angles in the molecule are within the values standard
for each type of the bond. The coordination polyhedron of
the pentavalent phosphorus atom is a distorted tetraꢀ
hedron, the phenoxyl substituents are turned mutually perꢀ
pendicularly and are localized at different sides from the
plane of the molecule (Fig. 1).
In the framework of the synthesis and study of the
properties of phosphorylated methylidene quinones,8—10
we developed the method of preparation of diphenyl
(3,5ꢀdiꢀtertꢀbutylꢀ4ꢀoxocyclohexaꢀ2,5ꢀdienylidene)ꢀ
methylphosphonate (2) by oxidation of diphenyl (3,5ꢀdiꢀ
tertꢀbutylꢀ4ꢀhydroxybenzyl)phosphonate (1) with an alkaꢀ
line solution of potassium ferricyanide (Scheme 1).
For the purpose of synthesizing phosphorylꢀcontainꢀ
ing sterically hindered phenols, we carried out the reacꢀ
tions of methylidene quinone 2 with phenol, pyrocateꢀ
chol, resorcinol, and hydroquinone. It is known10,11 that
phosphorylated methylidene quinones react with aliphatic
alcohols in the presence of catalytic amounts of mineral
acids to form dialkyl (αꢀalkoxyꢀ3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydrꢀ
oxybenzyl)phosphonates. When optimizing the condiꢀ
tions for the reaction between phosphorylated methꢀ
ylidene quinone 2 and phenol (Scheme 2), it turned out
to be efficient to use trifluoromethanesulfonic acid as
a catalyst: in the presence of its catalytic amounts, reacꢀ
tion product 3 formed in 87% yield in acetonitrile at room
temperature.
1
The structure of compound 2 was confirmed by Н,
13С, and 31Р NMR spectroscopy, IR spectroscopy, mass
spectrometry, and Xꢀray diffraction analysis. In the 1Н
NMR spectrum, signals of the aromatic Н(3) and Н(5)
protons neighboring to the 2,6ꢀdiꢀtertꢀbutyl moieties apꢀ
pear as two singlets at δ 7.20 and 7.88, respectively. Acꢀ
cording to the Xꢀray structure data, the bond lengths and
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1964—1967, October, 2011.
1066ꢀ5285/11/6010ꢀ1999 © 2011 Springer Science+Business Media, Inc.

2000
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 10, October, 2011
Shaekhov et al.
Scheme 3
C(20)
C(21)
C(19)
C(18)
C(25)
C(16)
O(15)
P(7)
C(17)
C(22)
C(26)
C(23)
C(6)
O(32)
C(27)
C(5)
O(8)
C(2)
C(3)
C(14)
C(9)
C(4)
C(28)
O(1)
C(30)
C(31)
C(13)
C(12)
C(10)
C(11)
C(29)
Fig. 1. Crystal structure of molecule 2. Thermal vibrational elꢀ
lipsoids of nonꢀhydrogen atoms are shown with 50% probability.
Scheme 2
Experimental
1
Н and 13С NMR spectra were recorded on a Bruker Avance
600 instrument at working frequencies of 600 and 150 MHz,
respectively, using residual signals of the deuterated solvent
(DMSOꢀd6) as standards. 31Р NMR spectra were obtained on
a Bruker MSLꢀ400 instrument with a working frequency of
166.93 MHz relative to 85% Н3РО4 as the external standard. IR
spectra were recorded on a Vector 22 FTIR spectrometer (Bruker)
in the range from 400 to 4000 cm–1. The matrixꢀactivated laser
desorption/ionization mass spectra were obtained on a MALDI
TOF/TOF timeꢀofꢀflight mass spectrometer (Bruker Daltonics).
Elemental analyses were carried out on a Carlo Erba EA 1108
elemental analyzer.
Single crystals of compound 2 were grown in DMSO. The
Xꢀray structure analysis of compound 2 was carried out at 20 °C
on a Bruker Smart APEX2 automated diffractometer (MoꢀKα
radiation, graphite monochromator, ω scan mode, θmax = 28.80°).
The crystal of compound 2 is monoclinic, C27H31O4P, М = 450.49,
space group P21/с, at Т = 296 °С: a = 8.918(2) Å, b = 24.427(6) Å,
c = 11.670(3) Å, β = 104.554(3)°, V = 2460.7(11) Å3, Z = 4,
F(000) = 960, dcalc = 1.216 g cm–3, μ = 0.141 mm–1. The strucꢀ
ture was solved by a direct method using the SIR program12 and
refined first in the isotropic and then in the anisotropic approxiꢀ
mation using the SHELXLꢀ97 program.13 The positions of hyꢀ
drogen atoms were calculated geometrically and refined in the
isotropic approximation. The final R factors were R1 = 0.0442
for 2829 independent reflections with I > 2σ(I) and wR2 = 0.1031
for all 5916 independent reflections.
i. PhOH, CF3SO3H, MeCN.
The structure and composition of compound 3 were
established from the data of Н and 31Р NMR spectroꢀ
scopy, IR spectroscopy, mass spectrometry (MALDIꢀ
TOF), and elemental analysis.
1
Diatomic phenols, such as pyrocatechol, hydroquinone,
and resorcinol, react with methylidene quinone 2 in the ratio
1 : 2 to form the corresponding bisꢀadducts 4—6 (Scheme 3).
Compounds 4—6 are mixtures of diastereomers, which
is confirmed by doubling of all signals in the 31Р and Н
1
NMR spectra. The signal of the proton at the Cα carbon
atom appears in compounds 4—6 in the region δ 5.0—5.25
as two doublets of the diastereomeric pair with spinꢀspin
coupling constants 2JP,H = 23.0—26.0 Hz. In the 13С NMR
spectrum, the signal from the carbon atom at the phosꢀ
phorus atom for compounds 4 and 5 lies in the region
δ 41.82—46.6 with the spinꢀspin coupling constants
1JP,С = 148—150 Hz.
In summary, the reaction of diphenyl (3,5ꢀdiꢀtertꢀ
butylꢀ4ꢀoxocyclohexaꢀ2,5ꢀdienylidene)methylphosphonꢀ
ate with phenols can serve as a convenient method for the
preparation of novel phosphorylated polyphenols containꢀ
ing sterically hindered moieties. The synthesized products
are promising as potential antioxidants.
All calculations were performed using the WinGX (see
Ref. 14) and APEX2 (see Ref. 15) programs. The figures of molꢀ
ecules and analysis of intermolecular interactions were made
using the ORTEP3 and PLATON programs.16,17 The crystalloꢀ

Phosphorylated bisꢀphenols
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 10, October, 2011
2001
graphic data were deposited with the Cambridge Crystallographic
Data Centre (CCDC 832621).
Solvents were purified and dehydrated using known proceꢀ
dures.18 Diphenyl (3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl)phosphoꢀ
nate was synthesized by a published procedure.19
115.86, 116.00 (both s, С(4)); 117.84, 118.32 (both d, С(3),
J = 155 Hz); 120.43, 120.68, 120.92, 121.07 (all d, С(9´),
J = 162 Hz); 125.93—126.89 (m, С(10´)); 130.02, 130.09 (both d,
С(2´), J = 162 Hz); 139.45, 139.84 (both s, С(3´)); 144.86, 144.98
(both s, С(1´)); 150.43, 150.50, 150.56, 150.63 (all s, С(8´)); 150.99,
151.05 (both s, С(4´)); 153.86, 153.92 (both s, С(1)). 31P NMR
(C6H6), δ: 22.42, 22.80. IR, ν/cm–1: 3628 (OH); 3123 (ОН);
1614, 1533 (Сarom); 1204 (Р=О); 1059 (POC). MS (MALDI),
m/z: 1011.43 [M]+, 1034.56 [M + Na]+, 1051.07 [M + K]+.
4,6ꢀBis[(3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxyphenyl)(diphenoxyphosꢀ
phoryl)methyl]resorcinol (5) was synthesized similarly to the preꢀ
vious compound from methylidene quinone 2 (1 g, 2.2 mmol) and
resorcinol (0.12 g, 1.1 mmol) in a yield of 0.98 g (97%), m.p.
195—197 °С (from pentane). Found (%): С, 70.52; Н, 6.94;
Р, 6.28. C60H68O10Р2. Calculated (%): С, 71.27; H, 6.78;
Р, 6.13. 1Н NMR, δ: 1.24, 1.30 (both s, 18 H each, C(CH3)3); 5.15,
5.20 (both d, 1 H each, PCH, JP,H = 26.00 Hz); 6.40 (br.s, 2 Н,
ОН); 6.46 (s, 1 H, Н(2)); 6.69 (d, 2 H, Н(9´), J = 8.05 Hz); 6.78,
6.82 (both d, 2 Н each, Н(9´), J = 8.30 Hz); 6.94 (d, 2 H, Н(9´),
J = 8.05 Hz); 7.05—7.16 (m, 8 Н, Н(10´)); 7.20 (t, 4 Н, Н(11´),
J = 7.90 Hz); 7.26 (s, 4 Н, Н(2´)); 7.46 (s, 1 Н, Н(5)); 9.64 (s, 2 Н,
ОН). 31P NMR (C6H6), δ: 21.89, 22.06. 13С NMR, δ: 30.86
(q, (СН3)3С, J = 125 Hz); 34.97, 35.02 (both s, (СН3)3С)); 41.82,
42.75 (both d, СHP, 1JС,Р = 150 Hz); 102.99 (d, С(2), J = 153 Hz);
114.75 (s, С(5)); 115.88, 119.32 (both d, С(4), J = 155 Hz);
120.43—121.07 (m, С(9´)); 125.93—126.89 (m, С(10´)); 130.02,
130.09 (both d, С(2´), J = 162 Hz); 139.45, 139.84 (both s, С(3´));
144.86, 144.98 (both s, С(1´)); 150.43—150.63 (m, С(8´));
150.99, 151.05 (both s, С(4´)); 153.86, 153.92 (both s, С(1)). IR,
ν/cm–1: 3646 (OH); 3134 (ОН); 1621, 1542 (arom.); 1218
(Р=О); 1061 (POC). MS (MALDI), m/z: 1011.67 [M]+, 1035.67
[M + Na]+, 1052.28 [M + K]+.
2,5ꢀBis[(3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxyphenyl)(diphenoxyphosꢀ
phoryl)methyl]hydroquinone (6) was synthesized similarly from
methylidene quinone (1 g, 2.2 mmol) and hydroquinone (0.12 g,
1.1 mmol) in a yield of 0.96 g (95%), m.p. 152—154 °С (from
pentane). Found (%): С, 68.92; Н, 7.02; Р, 7.16. C60H68O10Р2.
Calculated (%): С, 71.27; H, 6.78; Р, 6.13. 1Н NMR, δ: 1.22,
1.29 (both s, 18 H each, C(CH3)3); 5.06, 5.25 (both d, 1 H each,
PCH, JP,H = 27.00 Hz); 5.95 (s, 2 Н, ОН); 6.56 (s, 1 H, Н(3));
6.77 (d, 2 H, Н(9´), J = 8.00 Hz); 6.88, 6.99 (both d, 2 Н each,
Н(9´), J = 8.30 Hz); 7.04 (d, 2 H, Н(9´), J = 8.00 Hz); 7.07—7.17
(m, 8 Н, Н(10´)); 7.22 (t, 4 Н, Н(11´), J = 8.50 Hz); 7.34 (s, 4 Н,
Н(2´), Н(6´)); 7.58 (s, 1 Н, Н(6)); 8.25 (s, 2 Н, ОН). 31P NMR
(C6H6), δ: 21.32, 22.18. IR, ν/cm–1: 3637 (OH); 3162 (ОН);
1617, 1535 (arom.); 1206 (Р=О); 1057 (POC). MS (MALDI),
m/z: 1010.45 [M]+, 1034.45 [M + Na]+, 1051.43 [M + K]+.
Diphenyl (3,5ꢀdiꢀtertꢀbutylꢀ4ꢀoxocyclohexaꢀ2,5ꢀdienylidene)ꢀ
methylphosphonate (2). A solution of diphenyl (3,5ꢀdiꢀtertꢀbuꢀ
tylꢀ4ꢀhydroxybenzyl)phosphonate (1) (4.5 g, 1 mmol) in benzꢀ
ene (160 mL) was stirred with a solution of K3Fe(CN)6 (19.8 g,
0.06 mol) in 2 М КОН (180 mL) at room temperature for 3 h.
A colored benzene solution was separated, washed with water to
neutral pH, and dried with Na2SO4. Benzene was removed
in vacuo of a waterꢀjet pump. The yellow crystalline product was
isolated in a yield of 3.1 g (67%), m.p. 76 °С. Found (%): С, 69.74;
Н, 7.14; Р, 6.95. C27H31O4Р. Calculated (%): С, 71.98; H, 6.94;
1
Р, 6.88. Н NMR, δ: 1.15, 1.22 (both s, 18 Н each, (СН3)3С);
6.92 (d, 1 Н, РСН, JP,H = 16.8 Hz); 7.19 (s, 1 Н, Н(3)); 7.23
(t, 2 Н, Н(11), J = 7.6 Hz); 7.26 (t, 4 Н, Н(9), J = 8.4 Hz); 7.41
(t, 4 Н, Н(10), J = 8.05 Hz); 7.87 (s, 1 Н, Н(5)). 13С NMR, δ:
29.71 (q, (СН3)3С, J = 128 Hz); 35.6 (s, (СН3)3С)); 121.13
(d, С(9), J = 160.94 Hz); 126.26 (d, С(11), J = 160.21 Hz); 125.40
(d, С(7), JP,С = 182.9 Hz); 128.54 (d, С(3), JP,С = 7.18 Hz,
J = 160.03 Hz); 130.78 (d, С(10), J = 160.58 Hz); 134.3 (d, С(5),
JP,С = 26.81 Hz, J = 163.48 Hz); 147.00 (s, С(4)); 150.05
(s, С(2)); 150.66 (s, С(8), JP,С = 23.77 Hz); 186.39 (s, С(О)).
31Р NMR acetone), δ: 6.7. IR, ν/cm–1: 1648 (Сarom); 1631
(С=О); 1593 (С=СН); 1253 (Р=О); 932 (РОС). MS (MALDI),
m/z: 450.45 [M]+.
Diphenyl (3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxyphenyl)(4ꢀhydroxyꢀ
phenyl)methylphosphonate (3). A solution of phenol (0.1 g,
1.1 mmol) in acetonitrile (1 mL) was added to a solution of
methylidene quinone 2 (0.5 g, 1.1 mmol) in acetonitrile (2 mL).
Then trifluoromethanesulfonic acid (0.002 mL, 0.02 mol) was
added. The reaction mixture was kept at room temperature for
4 h, and the white precipitate that formed was filtered off and
washed with pentane. The product was dried in a vacuum of an
oil pump (1 h, 20 °С, 1 Torr), the yield was 0.52 g (87%), m.p.
138—140 °С (from pentane). Found (%): С, 70.34; Н, 6.47;
Р, 5.41. C33H37O5Р. Calculated (%): С, 72.78; H, 6.85; Р, 5.69.
1Н NMR, δ: 1.40 (s, 18 H, C(CH3)3); 4.65 (d, 1 H, PCH, JP,H
=
= 25.90 Hz); 5.95 (br.s, 2 Н, ОН); 6.61 (d, 2 H, Н(2),
J = 8.20 Hz); 6.73 (d, 2 Н, Н(3), J = 8.20 Hz); 6.87 (d, 2 H,
H(9´), J = 8.00 Hz); 7.05, 7.08 (both t, 2 H, Н(11´) J = 7.50 Hz),
7.15, 7.20 (both t, 2 Н each, Н(10´) J = 8.00 Hz); 7.33 (d, 2 Н,
H(9´), J = 8.00 Hz); 7.35 (s, 2 Н, Н(2´)). 31P NMR (CHCl3), δ:
19.65. IR, ν/cm–1: 3563 (OH); 3440 (ОН); 1613, 1516 (Сarom);
1210 (Р=О); 1036 (POC). MS (MALDI), m/z: 544.68 [M]+.
4,5ꢀBis[(3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxyphenyl)(diphenoxyphosꢀ
phoryl)methyl]pyrocatechol (4) was synthesized similarly to comꢀ
pound 3 from methylidene quinone (1 g, 2.2 mmol) and pyrocatꢀ
echol (0.12 g, 1.1 mmol) in a yield of 0.95 g (94%), m.p.
129—130 °С (from pentane). Found (%): С, 69.68; Н, 7.14;
Р, 6.56. C60H68O10Р2. Calculated (%): С, 71.27; H, 6.78; Р, 6.13.
1Н NMR, δ: 1.23, 1.30 (both s, 18 H each, C(CH3)3); 5.01, 5.21
(both d, 1 H each, PCH, JP,H = 27.00 Hz); 6.05 (br.s, 4 Н, ОН);
6.50, 6.52 (both d, 2 H each, Н(9´), J = 8.00 Hz); 6.66, 6.82
(both d, 2 Н each, Н(9´), J = 8.0 Hz); 7.05 (s, 2 Н, Н(2´));
7.07—7.17 (m, 8 Н, Н(10´); 7.19—7.22 (m, 4 Н, Н(11´)); 7.41
(s, 2 Н, Н(6´)); 7.43 (s, 1 Н, Н(3)); 7.60 (s, 1 Н, Н(6)). 13С NMR,
δ: 30.76, 30.86 (both q, (СН3)3С, J = 125 Hz); 34.96, 35.12
(both s, (СН3)3С)); 45.16, 46.49 (both d, СHP, 1JС,Р = 148 Hz);
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 11ꢀ03ꢀ00416a)
and the Ministry of Education and Science of the Russian
Federation (Federal Target Program "Scientific and Sciꢀ
entific Pedagogical Personnel of Innovative Russia", State
Contract No. P837).
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Received August 8, 2011;
in revised form September 21, 2011