Russian Journal of General Chemistry, Vol. 72, No. 5, 2002, pp. 818 819. Translated from Zhurnal Obshchei Khimii, Vol. 72, No. 5, 2002,
pp. 875 876.
Original Russian Text Copyright
2002 by Ismagilov, Moskva, Ofitserov, Shamsutdinova.
LETTERS
TO THE EDITOR
Ethoxydeamination of -Phenylaminobenzylphosphonate
Derivatives
R. K. Ismagilov, V. V. Moskva, E. N. Ofitserov, and L. P. Shamsutdinova
Kazan State Technological University, Kazan, Tatarstan, Russia
Received July 5, 2001
-Substituted phosphonates are being intensively
studied [1 3]. We showed that the reactions of diethyl
( -phenylamino-3,5-di-tert-butyl-4-hydroxybenzyl)-
phosphonate and diphenyl( -phenylamino-3,5-di-tert-
butyl-4-hydroxybenzyl)phosphine oxide with ethanol
in the presence of hydrochloric acid involve substitu-
tion of the phenylamino group by ethoxyl. This find-
benzyl)phosphonate (I). A solution of 0.55 g of di-
ethyl ( -phenylamino-3,5-di-tert-butyl-4-hydroxy-
benzyl)phosphonate in 10 ml of ethanol and 3 ml of
concentrated hydrochloric acid was refluxed for 1 h
and then allowed to reduce by half at room tempera-
ture (24 h). 3,5-Di-tert-butyl-4-hydroxybenzaldehyde,
0.05 g, precipitated, mp 188 189 C (from alcohol)
ing is at variance with what has been reported in [1, 2]. {mp 188 189 C [6]}. The coarse crystals that formed
after volatile components had been almost completely
O
removed were washed on a filter with aqueous alcohol
(1:1) to obtain 0.22 g (37%) of compound I, mp 135
138 C (heptane) (mp 137 138 C [7]).
R2P CH
OH + EtOH
NHPh
1
The IR and H NMR spectra of 3,5-di-tert-butyl-4-
O
hydroxybenzaldehyde and compound I are identical
to those of authentic samples, and mixed samples give
no melting point depression.
HCl
R2P CH
OEt
OH
PhNH2 HCl
Diphenyl( -ethoxy-3,5-di-tert-butyl-4-hydroxy-
benzyl)phosphine oxide (II). a. A solution of 0.47 g
of diphenyl( -phenylamino-3,5-di-tert-butyl-4-hydr-
oxybenzyl)phosphine oxide in a mixture of 5 ml of
ethanol and 2 ml of concentrated hydrochloric acid
was refluxed for 1.5 h and then treated as described
above to obtain 0.03 g of 3,5-di-tert-butyl-4-hydroxy-
benzaldehyde, mp 184 186 C (alcohol), and 0.31 g
(62%) of compound II, mp 145 149 C (hexane). IR
I, II
R = OEt (I), Ph (II).
The presence in the reaction mixture of only traces
of 3,5-di-tert-butyl-4-hydroxybenzaldehyde suggests
an inconsiderable contribution of full hydrolysis
which is characteristic of unsubstituted -phenyl-
aminobenzylphosphonates in acid media [4, 5].
1
spectrum, , cm : 3350 sh (OHass), 1595 (C6H5),
1
1190 (COC), 1150 (P=O). H NMR spectrum (CCl4 +
The effect of structural factors on the above reac-
tion pathway can be explained by a scheme involving
protonation of the nitrogen atom, elimination of
aniline hydrochloride, and formation of intermediate
-phosphorylated 2,6-di-tert-butyl-4-methylene-2,5-
cyclohexadienone.
acetone-d6), , ppm: 1.1 t (3H, CH3), 1.21 s [18H,
C(CH3)3], 3.42 m (2H, OCH2), 4.85 d (1H, PCH, 2JPH
4
12.5 Hz), 5.31 s (1H, OH), 6.8 d (2H, C6H2, JHH
2 Hz), 7.45 m (5H, C6H5), 7.82 m (5H, C6H5). Found,
%: P 6.95, 6.80. C29H37O3P. Calculated, %: P 6.68.
b. To a solution of 0.42 g of -diphenylphosphino-
yl-2,6-di-tert-butyl-4-methylene-2,5-cyclohexadienone
in 10 ml of ethanol we added 2 drops of sulfuric acid,
and the mixture was refluxed for 1 h, after which the
alcohol was removed by vacuum distillation, and the
residue was treated with hexane to obtain 0.20 g
(47%) of compound II, mp 149 150 C (heptane).
Compound II was obtained by independent syn-
thesis. The reaction of ethanol with -diphenylphos-
phinoyl-2,6-di-tert-butyl-4-methylene-2,5-cyclohexa-
dienone in the presence of catalytic amounts of sul-
furic acid occurs by the 1,6-addition scheme.
Diethyl ( -ethoxy-3,5-di-tert-butyl-4-hydroxy-
1070-3632/02/7205-0818$27.00 2002 MAIK Nauka/Interperiodica