Tertiary phosphine oxides in reaction with benzaldehyde

Article abstract of DOI:10.1023/A:1026340532022

Symmetrical and unsymmetrical tertiary phosphine oxides containing benzyl and 5-chloro-2-thienyl radicals stereoselectively react with benzaldehyde in the sodium amide-THF system to form the E isomers of 1-organyl-2-phenylethene and diorganylphosphinic ac

Full text of DOI:10.1023/A:1026340532022

Russian Journal of General Chemistry, Vol. 73, No. 6, 2003, pp. 877 879. Translated from Zhurnal Obshchei Khimii, Vol. 73, No. 6, 2003,
pp. 927 929.
Original Russian Text Copyright
2003 by Ivanova, Gusarova, Reutskaya, Shaikhutdinova, Arbuzova, Trofimov.
Tertiary Phosphine Oxides in Reaction with Benzaldehyde
N. I. Ivanova, N. K. Gusarova, A. M. Reutskaya,
S. I. Shaikhutdinova, S. N. Arbuzova, and B. A. Trofimov
Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences, Irkutsk, Russia
Received May 21, 2001
Abstract Symmetrical and unsymmetrical tertiary phosphine oxides containing benzyl and 5-chloro-2-
thienyl radicals stereoselectively react with benzaldehyde in the sodium amide THF system to form the E
isomers of 1-organyl-2-phenylethene and diorganylphosphinic acids in high yields. Triethyl, tris(2-phenyl-
ethyl)-, and tris[(4-methoxyphenyl)methyl]phosphine oxides under the above-mentioned conditions do not
react with benzaldehyde.
Recently we reported [1 3] that symmetrical tri-
benzylphosphine oxide Ia under conditions of the
Wittig Horner reaction have opened fresh opportuni-
ties for stereoselective synthesis of 1,2-disubstituted
alkenes, including functionally substituted alkenes and
their hetero analogs, which are promising optical
switches and photochemical sensors [4, 5], inter-
mediate products for production of dyes, optical
bleachers, complex-forming agents and clusters [6],
drugs [7, 8], and natural antioxidants and chelating
agents like pinosylvin and resveratrol [8, 9].
tertiary phosphine oxides [10 12] toward benzal-
dehyde.
It was found that in the reaction studied, along with
tribenzylphosphine oxide (Ia), its hetero analog, tris-
[(5-chloro-2-thienyl)methyl]phosphine oxide (Ib), as
well as unsymmetrical benzyldiethyl- and dibenzyl-
ethylphosphine oxides (Ic, Id) can be successfully
used. Successive treatment of phosphine oxides Ia Id
with NaNH2 THF, benzaldehyde (at 58 60 C), and
aqueous HCl (at room temperature) gives the E iso-
mers of 1,2-diphenylethene (IIa) (with phosphine
oxides Ia, Ic, Id) and 1-thienyl-2-phenylethene (IIb)
(with phosphine oxide Ib). In this way we also pre-
pared previously unknown or hardly available di-
benzyl, bis[(5-chloro-2-thienyl)methyl]-, diethyl-, and
benzylethylphosphinic acids IIIa IIId in yields of up
to 65%.
In the present work, with the purpose of extending
the preparative potential of the Wittig Horner reaction,
we have explored the reactivity of new available
(prepared from elemental phosphorus and organyl
halides or styrene) symmetrical and unsymmetrical
1) NaNH2/THF
2) HCl/H2O
R1
R2
R1
H
IIa, IIb
R2
R3
O
O
H
O
H
Ph
+
P
+ Ph C
P
R3
OH
IIIa IIId
(1)
Ia Id
(Ib IIIb); R1 = Ph, R2 = R3 = Me (Ic, IIa, IIIc);
R1 = R2 = R3 = Ph (Ia IIIa); R1 = R2 = R3 =
Cl
S
R1 = R2 = Ph, R3 = Me (Id, IIa, IIId).
The electron-acceptor phenyl and thienyl radicals
in the methylenephosphoryl group in phosphine
oxides Ia Id favor reaction (1) by stabilizing inter-
mediate carbanion A. At the same time, tris[(4-me-
thoxyphenyl)methyl]phosphine oxide under the above
conditions fails to react with benzaldehyde, which can
be explained by destabilization of the carbanion by
the electron-donor methoxy group (p conjugation).
1070-3632/03/7306-0877$25.00 2003 MAIK Nauka/Interperiodica

878
IVANOVA et al.
O
H
1) Ph C
;
R1
R2
O
2) HCl/H2O
NaNH2/THF
Ia Id
P
IIa, IIb + IIIa IIId
(2)
R3
A
An even stronger anion-destabilizing effect is
characteristic by alkyl and phenylalkyl radicals, be-
cause of which we could involve triethyl- and tris-
(2-phenylethyl)phosphine oxides in reaction (1).
E-1,2-Diphenylethene (IIa), yield 88, 70, and
62% from phosphine oxides Ia, Ic, and Id, respec-
tively. The constants and spectral data of ethene IIa
agree with those reported in [1, 14].
These results complement the known data [13]
concerning the determining role of the nature of sub-
stituents in triorganylphosphine oxides in their de-
protonation under conditions of the Wittig Horner
reaction. The synthetic material presented in this work
considerably extends the range of application of the
Wittig Horner reaction for stereoselective synthesis
of substituted stylbenes and suggest that this strategy
can be succssfully extended to hetero analogs of
benzyl halides having substituents in the heteroring.
E-1-(5-Chloro-2-thienyl)-2-phenylethene (IIb),
1
yield 71%, mp 66-68 C. H NMR spectrum, , ppm:
3
6.79 s, 6.80 s (2H, H3, H4), 6.78 d (1H, H , JHH
3
15.8 Hz), 7.06 d (1H, H , JHH 15.8 Hz), 7.24 t (1H,
Hp), 7.33 t (2H, Hm), 7.43 d (2H, Ho). The H and H
1
signals were assigned on the basis of the 1H H
NOEZSY spectrum which showed a cross peak cor-
responding to H Ho coupling. Since the signals of
H3 and H4 protons and one of the components of the
1
H
doublet in the H NMR spectrum overlap, the
H,C-correlation (HMQC) experiment was performed
EXPERIMENTAL
for signal assignment. 13C NMR spectrum, C, ppm:
124.03 (C ), 128.02 (cross peak with the proton at
6.80, C3, or C4), 129.02 (Co), 129.40 (cross peak with
the proton at 6.79, C3, or C4), 130.54 (Cp), 131.22
The H and 31P NMR spectra were recorded on a
1
Bruker DPX-400 spectrometer in CDCl3 against in-
ternal HMDS and external 85% phosporic acid, res-
pectively. The IR spectra were recorded on a Specord
75-IR spectrometer.
(C ), 131.43 (Cm). Found, %: C 64.83; H 4.08; Cl
16.11; S 14.39. C12H9ClS. Calculated, %: C 65.30; H
4.11; Cl 16.06; S 14.53.
Synthesis of 1-organyl-2-phenylethenes IIa, IIb
and diorganylphosphinic acids IIIa IIId (general
procedure. Sodium amide, 6.6 mmol, was added to a
solution of 2.2 mmol of triorganylphosphine oxide in
40 ml of THF heated to 58 60 C. The resulting mix-
ture was stirred for 1 h at 58 60 C and, after
2.2 mmol of benzaldehyde had been added, refluxed
for 1 h, cooled, diluted with 35 ml of water, and
extracted with ether (3 10 ml). The ethereal extract
was washed with water (2 8 ml), dried over potas-
sium carbonate, the ether was removed, and the
residue was dried in a vacuum to obtain (E)-1-orga-
nyl-2-phenylethene IIa, IIb. The aqueous layers were
combined and acidified with 2 N HCl to pH 2 3. The
precipitate that formed was successively washed with
water, ethanol, ether, and dried in a vacuum to obtain
diorganylphosphinic acid IIIa, IIIb. In the case of
formation of water-soluble acids, the aqueous fraction
was acidified and extracted with chloroform to obtain
acid IIIc, IIId. Acid IIId was not isolated pure, and
is probably present in the aqueous fraction among four
organophosphorus compounds ( P 49.48, 46.20, 45.36,
and 38.09 ppm, integral intensity ratio the 31P NMR
signals 20:48:10:22).
Dibenzylphosphinic acid (IIIa), yield 65%, mp
189 190 C (from ethanol) (published data [15]: mp
1
191 C). H NMR spectrum, , ppm: 2.85 d (4H, CH2,
2JPH 16.9 Hz), 7.21 m (10H, C6H5), 9.02 s (1H, OH).
31P NMR spectrum, P, ppm: 49.48. Found, %: C
67.92; H 6.13; P 12.71. C14H15O2P. Calculated, %: C
68.29; H 6.14; P 12.58.
Bis[(5-chloro-2-thienyl)methyl]phosphinic acid
1
(IIIb), yield 39%, mp 168 170 C (from ethanol). H
2
NMR spectrum, , ppm: 3.16 d (4H, CH2P, JPH
3
16.3 Hz), 6.77 t (2H, H3), 6.99 d (2H, H4, JHH
4.0 Hz). 31P NMR spectrum, P, ppm: 46.6. Found,
%: C 36.83; H 2.73; Cl 21.68; P 9.56; S 19.43.
C10H9Cl2O2PS2. Calculated, %: C 36.71; H 2.77; Cl
21.67; P 9.47; S 19.60.
Diethylphosphinic acid (IIIc), yield 48%, bp
194 195 C (21 mm) [16]. 1H NMR spectrum, , ppm:
1.05 t (6H, CH3), 1.81 m (4H, CH2), 9.08 s (1H, OH).
31P NMR spectrum, P, ppm: 51.8. Found, %: C
39.87; H 9.23; P 25.66. C4H11O2P. Calculated, %: C
39.35, H 9.08, P 25.37.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 73 No. 6 2003

TERTIARY PHOSPHINE OXIDES IN REACTION WITH BENZALDEHYDE
879
REFERENCES
8. FR Pat. Appl. 2766176, Ref. Zh. Khim., 2000,
19 O 204P.
1. Gusarova, N.K., Ivanova, N.I., Reutskaya, A.M., Ar-
buzova, S.N., and Trofimov, B.A., Zh. Obshch. Khim.,
1999, vol. 69, no. 11, pp. 1922 1923.
9. Wang, Minfu, Jin, Yi, and Ho, Chi-tang, J. Agr. Food
Chem., 1999, vol. 47, no. 10, pp. 3974 3977.
10. Gusarova, N.K., Malysheva, S.F., Arbuzova, S.N., and
Trofimov, B.A., Izv. Ross. Akad. Nauk, Ser. Khim.,
1998, no. 9, pp. 1695 1702.
2. Ivanova, N.I., Reutskaya, A.M., Arbuzova, S.N.,
Baikalova, L.V., Afonin, A.V., Gusarova, N.K., and
Trofimov B.A., Khim. Geterotsikl. Soedin., 2000,
no. 2, p. 262.
11. Trofimov, B.A., Malysheva, S.F., Gusarova, N.K.,
Rakhmatullina, T.N., Dmitriev, V.I., Shaikhutdino-
va, S.I., and Larin, M.F., USSR Inventor’s Certifi-
cate 1680703, Byull. Izobret., 1991, no. 36.
3. Reutskaya, A.M., Zyryanova, I.A., Gusarova, N.K.,
and Trofimov, B.A., Abstracts of Papers, Molodezh-
naya nauchnaya shkola-konferentsiya Aktual’nye
problemy organicheskoi khimii (Youth School Conf.
Actual Problems of Organic Chemistry ), Ekaterin-
burg, 2001, p. 221.
12. Gusarova, N.K., Shaikhutdinova, S.I., Reutskaya, A.M.,
Ivanova, N.I., Tatarinova, A.A., and Trofimov, B.A.,
Izv. Ross. Akad. Nauk, Ser. Khim., 2000, no. 7,
pp. 1323 1324.
4. Simeonov, A., Matsushita, M., Juban, E.A., Thom-
pson, E.H.N., Hoffman, T.Z., Beucher, A.E., Tay-
lor, M.J., Wirsching, P., Rettig, W., McCusker, J.K.,
Stevens, R.C., Millar, D.P., Schultz, P.G., Ler-
ner, R.A., and Janda, K.D., Science, 2000, vol. 290,
pp. 307 313.
13. Buss, A.D. and Warren, S., J. Chem. Soc., Perkin
Trans. 1, 1985, no. 11, pp. 2307 2325.
14. Boutagy, J. and Thomas, R., Chem. Rev., 1974,
vol. 74, no. 1, pp. 87 99.
15. Kudryavtseva, L.I. and Feshchenko, N.G., Zh. Obshch.
Khim., 1981, vol. 51, no. 2, pp. 478 479; Kudryav-
tseva, L.I., Zh. Obshch. Khim., 1989, vol. 59, no. 5,
pp. 1027 1031.
5. Braumann, J.I., Science, 2000, vol. 290, pp. 286 287.
6. Takahiro, K. and Makoto, F., J. Am. Chem. Soc.,
1999, vol. 121, no. 6, pp. 1397 1398.
7. Klauden, J. and Warren, S., Angew. Chem., 1996,
16. Kosolapoff, G.M. and Struck, R.F., J. Chem. Soc.,
vol. 108, no. 3, pp. 261 291.
1959, no. 12, pp. 3950 3952.
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