Synthesis of optically active α-aminophosphine oxides and enantioselective membrane transport of acids with their participation

Full text of DOI:10.1134/S107036321104027X

ISSN 1070-3632, Russian Journal of General Chemistry, 2011, Vol. 81, No. 4, pp. 773–774. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © R.A. Cherkasov, A.R. Garifzyanov, S.A. Koshkin, 2011, published in Zhurnal Obshchei Khimii, 2011, Vol. 81, No. 4, pp. 683–684.
LETTERS
TO THE EDITOR
Synthesis of Optically Active α-Aminophosphine Oxides
and Enantioselective Membrane Transport of Acids
with Their Participation
R. A. Cherkasov, A. R. Garifzyanov, and S. A. Koshkin
Kazan (Volga Region) Federal University, ul. Kremlevskaya 18, Kazan, 420008 Russia
e-mail: scioris@yandex.ru
Received November 18, 2010
DOI: 10.1134/S107036321104027X
Previously, we have shown the prospect of using
lipophilic α-aminophosphine oxides in the processes of
membrane extraction for efficient and selective
extraction of substrates of different nature, including
mineral and organic acids [1]. We first attempted to
carry out the enantioselective membrane transport of
chiral carboxylic acids with optically active α-amino-
phosphine oxides. For their synthesis we used the
Kabachnik–Fields reaction in the three-component
system phosphinous acid–formaldehyde–amine. The
stereogenic carbon atom was introduced into the
structure of α-aminophosphine oxides by using the (R)-
enantiomer of α-methylbenzylamine. The chiral center
on the phosphorus atom was introduced by the reaction
of racemic decylphenylphosphinous acid followed by
the separation of stereoisomers mixture. The reactions
were carried out in the boiling toluene, using a small
(4%) excess of formaldehyde and catalyzing with p-
toluenesulfonic acid.
Optically pure α-aminophosphine oxides I were
prepared in 94% yield by reacting didecylphosphinite
with formaldehyde and (R)-α-methylbenzylamine for
3 h and were purified by recrystallization from hexane.
O
O
H2N
H+
+ CH2O
P
+
*CH
P
HN
−H2O
H
*
C10H21
C10H21
C10H21
C10H21
CH2
CH
H3C
CH3
(RC)-I
(R)
The longer heating (5 h) was required in the case of
the reaction of decylphenylphosphinous acid with
formaldehyde and 2-aminopyridine, which gave rise to
aminophosphine oxide II.
O
O
H+
*
P
HN
*
P
N
+ CH2O +
−H2O
C10H21
H
CH2
C10H21
Ph
H2N
N
Ph
II
The formation of aminophosphine oxide II as a
racemic mixture is characterized by the appearance in
the 31P{H} NMR spectrum of the signals of two
enantiomeric products (38.7 and 39.5 ppm); a singlet at
40.5 ppm corresponds to them in chloroform solution
that may testify to the diastereomeric associates
formation [2].
For the racemate resolution, the aminophosphine
oxide II was converted into the tartrate salt via the
773

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CHERKASOV et al.
reaction with an equimolar amount of D-tartaric acid in
ethanol. Further fractional crystallization of the result-
ing tartrate and the conversion of α-aminophosphine
oxide into the basic form by the action of sodium
carbonate resulted in the isolation of (–)-stereoisomer.
The attempts to isolate (+)-enantiomer have not been
successful.
–4.95° (с 2, С6H5СH3), pKBH 4.65 (isopropanol–
+
water, 1:1). 31P{H} NMR spectrum (С6H5CH3), δР,
ppm: 38.7, 39.5. 31P{H} NMR spectrum (CHCl3), δР,
1
ppm: 40.5. H NMR spectrum (СDCl3), δ, ppm: 0.89–
2.09 m (24Н, С10Н21, СН3), 4.08 m (2Н, РСН2N), 4.37
s (1Н, NH), 6.5–6.6, 8.06 m (3Н, C5H3N), 7.37–7.81
m (5Н, С6H5). IR spectrum, ν, cm–1: 3385 s (NH),
1130 s (Р=О), 1653 m, 1561 br.s (CH, pyridine), 1443
m, 1530 br.s (CHAr).
The study of membrane transport of D- and L-
tartaric acids with aminophosphine oxide I under the
conditions given in [1] showed that the rate of transfer
of the L-form (40×10–6 mol min–1 m–2) through an
impregnated membrane is 4.4 times higher compared
with the corresponding D-form (9.1×10–6 mol min–1 m–2).
The results obtained indicate suitability of the enan-
tiomeric aminophosphine oxide for the enantio-
selective membrane transport of acidic chiral substrates.
1
The H and 31P{H} NMR spectra were registered
on a Varian XL-300 spectrometer operating at 300 and
122.4 MHz respectively. The IR spectra were Regis-
tered on a Fourier-spectrometer Tensor 27 (Bruker) in
mineral oil.
ACKNOWLEDGMENTS
(R)-Didecyl-(N-1-phenylethyl)aminomethylphos-
phine oxide (I). Yield 94%. White crystals, mp 47°С,
This work was financially supported by the Russian
Foundation for Basic Research (grant no. 10-03-
00580).
pKBH
4.13 (isopropanol–water, 1:1). 31P{H} NMR
+
spectrum (С6H5CH3), δР, ppm: 43.87. 1H NMR
spectrum (СDCl3), δ, ppm: 0.85–1.7 m (15Н, 2С6Н11,
2
CH3), 2.66 d.d.d (2Н, СН2Р, 2JHH 15, JРH 64.5 Hz),
REFERENCES
3.69 q (Н, СН, 3JHH 6 Hz), 7.27 m (5Н, С6Н5). IR
spectrum, ν, cm–1: 3367 s (NH), 1156 s (Р=О), 1458
m, 1465 s (CHAr).
1. Cherkasov, R.A., Garifzyanov, A.R., Talan, A.S.,
Davletshin, R.R., and Kurnosova, N.M., Zh. Obshch.
Khim., 2009, vol. 79, no. 9, p. 1480.
(–)-Didecylphenyl-(N-2-pyridinyl)aminomethylphos-
phine oxide (II). Yellow amorphous substance. [αD23]
2. Kabachnik, M.I., Mastryukova, T.А., and Vaisberg, M.S.,
Usp. Khim., 1978, vol. 47, no. 9, p. 1541.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 81 No. 4 2011