Synthesis and dimerization of dibutyl (3,5-di-tert-butyl-4-oxo-2,5- cyclohexadienylidenemethyl)phosphonate

Full text of DOI:10.1007/s11172-012-0335-8

Russian Chemical Bulletin, International Edition, Vol. 61, No. 12, pp. 2367—2369, December, 2012
2367
Synthesis and dimerization of dibutyl
(3,5ꢀdiꢀtertꢀbutylꢀ4ꢀoxoꢀ2,5ꢀcyclohexadienylidenemethyl)phosphonate
T. R. Shaekhov, E. M. Gibadullina, Yu. K. Voronina, A. R. Burilov, and M. A. Pudovik
A. E. Arbuzov Institute of Organic and Physical Chemistry Kazan Scientific Center of the Russian Academy of Sciences,
8 ul. Akad. Arbuzova, 420088 Kazan, Russian Federation.
Fax: +7 (843) 275 2253. Eꢀmail: elmirak@iopc.ru
trometer (in KBr pellets for crystalline samples) in the range of
400—4000 cm–1. Mass spectra of the matrixꢀactivated laser desꢀ
orption/ionization (MALDI) were obtained on a Bruker Dalꢀ
tonics MALDI TOF/TOF timeꢀofꢀflight mass spectrometer.
Elemental analysis was performed on a CarloꢀErba EA 1108
elemental analyzer. A crystal of compound 3 (C46H78O8P2,
M = 821.02) is orthorhombic, space group Pbcn, at 296 K
While studing the synthesis and properties of phosphoꢀ
rylated methylenequinones,1—5 we have accessed dibutyl
(3,5ꢀdiꢀtertꢀbutylꢀ4ꢀoxoꢀ2,5ꢀcyclohexadienylidenemethꢀ
yl)phosphonate (1) by oxidation of dibutyl (3,5ꢀdiꢀtertꢀ
butylꢀ4ꢀhydroxybenzyl)phosphonate (2) with alkaline poꢀ
tassium ferrihexacyanide (Scheme 1).
3
The structure and composition of compound 1 were
a = 17.521(5), b = 14.434(4), c = 19.997(6) Å, V = 5057(3) Å ,
1
established based on the H, 31P NMR and IR spectroꢀ
Z = 4, F(000) = 1792, dcalc = 1.078 g cm–3,  = 0.131 mm–1
.
scopic data, mass spectrometric (MALDI) data, and eleꢀ
mental analysis. We found that with time compound 1
undergoes dimerization leading to 1,2ꢀbis(dibutoxyphosꢀ
phoryl)ꢀ1,2ꢀbis(3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxyphenyl)ethane
(3). The process reached completion within 10 days, which
was indicated by the disappearance in the 31P NMR specꢀ
trum of the signal for the starting compound 1 (P 15.0)
and the presence of the only singlet for the dimerization
product 3 (P 27.5). The structure and composition
Parameters of the unit cell and intensities of 36391 reflections
were measured on a Smart Apex II CCD diffractometer (296 K,
MoꢀK irradiation, graphite monochromator, ꢀ and ꢀscan
technique, 
= 26.0). The structure was solved by direct
max
method using the SIR program6 and refined first in isotropic and
then in anisotropic approximation using the SHELXLꢀ97 proꢀ
gram.7 Positions of hydrogen atoms were calculated geometriꢀ
cally and refined in isotropic approximation. The final Rꢀfacꢀ
tors: R1 = 0.0775 for 2105 independent reflections with I > 2(I)
and wR2 = 0.2860 for 4972 independent reflections. All the calꢀ
culations were carried out using the WinGX8 and APEX2 proꢀ
grams.9 The figures of the molecules were performed using the
ORTEP3 and PLATON programs.10—11 The hydrogen atom of
the hydroxy group containing atom O(12) was not found in the
differential Fourierꢀsynthesis because of the low reflecting abiliꢀ
ty of the crystal and the high degree of disorder in it. Thus, both
nꢀbutyl groups are disordered over two positions with the popuꢀ
lations of 0.68 : 0.32 and 0.78 : 0.22, respectively. The crystalloꢀ
graphic data were deposited with the Cambridge Structural Daꢀ
tabase CCDC (the structure number 884917).
1
of compound 3 were confirmed by the H, 31P NMR
and IR spectroscopic data, mass spectrometric (MALDI)
data, elemental analysis, and Xꢀray diffraction studies
(Fig. 1).
It should be noted that in the solution in benzene,
methylenequinone 1 did not undergo visible changes over
prolonged period of time.
1
H NMR spectra were recorded on a Bruker Avanceꢀ600
spectrometer (600 MHz) relative to the signals of residual proꢀ
tons of the deuterated solvent (DMSOꢀd6), 31P NMR spectra
were recorded on a Bruker MSLꢀ400 spectrometer (166.93 MHz)
relative to the 85% aqueous H3PO4 as an external standard.
IR spectra were recorded on a Bruker Vector 22 Fourierꢀspecꢀ
Solvents were purified and dried according to the known
procedures.12 Dibutyl (3,5ꢀdiꢀtertꢀbutylꢀ4ꢀhydroxybenzyl)phosꢀ
phonate (2) was synthesized using procedure described earlier.13
Dibutyl (3,5ꢀdiꢀtertꢀbutylꢀ4ꢀoxoꢀ2,5ꢀcyclohexadienylideneꢀ
methyl)phosphonate (1). A solution of dibutyl (3,5ꢀdiꢀtertꢀbutylꢀ
Scheme 1
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2344—2346, December, 2012.
1066ꢀ5285/12/6112ꢀ2367 © 2012 Springer Science+Business Media, Inc.

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Russ.Chem.Bull., Int.Ed., Vol. 61, No. 12, December, 2012
Shaekhov et al.
C(28A)
C(19)
C(27A)
C(26A)
C(25A)
C(7)
C(18)
C(17)
C(24A)
C(22A)
O(4)
C(21A)
C(23A)
O(3)
C(8)
C(20)
O(12)
C(14)
C(13)
P(2)
C(15a)
C(9)
C(16a)
C(6)
C(5)
C(10)
C(15)
O(2)
C(13a)
C(10a)
C(9a)
C(11a)
O(2a)
P(2a)
C(14a)
C(6a)
C(11)
O(3a)
C(16)
C(5a)
O(12a)
C(7a)
C(8a)
C(17a)
C(25Aa)
O(4a)
C(20a)
C(18a)
C(23Aa)
C(21Aa)
C(22Aa)
C(19a)
C(24Aa)
C(26Aa)
C(27Aa)
C(28Aa)
Fig. 1. Molecular structure of compound 3. The hydrogen atoms and the disorder of the C(21)—C(22)—C(23)—C(24) and
C(25)—C(26)—C(27)—C(28) chains are not shown. Ellipsoids of anisotropic thermal vibrations are given with 20% probability.
4ꢀhydroxybenzyl)phosphonate (2) (4.1 g, 10 mmol) in benzene
(160 mL) was stirred with a solution of K3Fe(CN)6 (24.6 g,
60 mmol) in 2 M KOH (180 mL) for 3 h at 20 C. The colored
benzene solution was separated, washed with water to neutrality,
and dried with anhydrous Na2SO4. Benzene was evaporated
in vacuo using a waterꢀjet pump, the residue was washed with
pentane and dried in vacuo to obtain reddish brown tarꢀlike prodꢀ
uct 1 (3.9 g, 97%). Found (%): C, 66.84; H, 9.47; P, 7.26.
C23H39O4P. Calculated (%): C, 67.29; H, 9.58; P, 7.54. 1H NMR
(CDCl3), : 0.72 (m, 6 H, CH3(CH2)2); 1.07 (m, 18 H, (CH3)3C);
1.22 (m, 4 H, —CH3CH2—); 1.46 (m, 4 H, —CH2CH2O); 3.80
(br.s, 4 H, —CH2CH2O); 5.80 (d, 1 H, PCH, JP,H = 14.0 Hz);
6.06 (s, 1 H, Harom); 7.79 (s, 1 H, Harom). 31P NMR (CDCl3),
: 15.4. IR (neat), /cm–1: 1634 (C=O), 1596 (C=CH), 1251
(P=O), 934 (POC). MS, m/z: 410.50 [M]+.
2.98 (m, 4 H, —CH2CH2O); 3.44 (m, 2 H, —CH2CH2O); 3.53
(m, 2 H, —CH2CH2O); 3.73 (d, 1 H, —CH—CH—, J = 7 Hz);
3.74 (d, 1 H, —CH—CH—, J = 7 Hz); 5.13 (s, 2 H, OH);
7.36 (br.s, 4 H, Harom). 31P NMR (DMSOꢀd6), : 27.57. IR,
/cm–1: 1648 (Carom), 1251 (P=O), 934 (POC). MS, m/z:
824.13 [M]+.
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 12ꢀ03ꢀ97041)
and the Ministry of Education and Science of the Russian
Federation (Federal Target Program "Scientific and Sciꢀ
entificꢀPedagogical Specialists of the Innovative Russia,
GK No. P837).
1,2ꢀBis(dibutoxyphosphoryl)ꢀ1,2ꢀbis(3,5ꢀdiꢀtertꢀbutylꢀ4ꢀ
hydroxyphenyl)ethane (3). Compound 1 (0.8 g) was allowed to
stand at room temperature for 10 days. A crystalline product
formed was washed with pentane several times and dried in vacꢀ
uo using a waterꢀjet pump to obtain light yellow product 3 (0.6 g,
74%). M.p. 223—226 C (pentane). Found (%): C, 67.38; H,
10.20; P, 7.64. C46H80O8P2 Calculated (%): C, 67.13; H, 9.80;
P, 7.53. 1H NMR (DMSOꢀd6), : 0.69 (t, 6 H, CH3CH2,
J = 7 Hz); 0.76 (t, 6 H, CH3CH2, J = 7 Hz); 0.94—1.14 (m, 16 H,
CH3(CH2)2); 1.46 (s, 36 H, (CH3)3C); 2.86 (m, 2 H, —CH2CH2O);
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Received June 27, 2011;
in revised form December 4, 2012