Synthesis of β-Enaminophosphonates and β-Methoxyiminophosphonates

Full text of DOI:10.1134/S1070363209120263

ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 12, pp. 2703–2704. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © E.V. Grishkun, O.I. Kolodyazhnyi, 2009, published in Zhurnal Obshchei Khimii, 2009, Vol. 79, No. 12, pp. 2065–2066.
LETTERS
TO THE EDITOR
Synthesis of β-Enaminophosphonates
and β-Methoxyiminophosphonates
E. V. Grishkun and O. I. Kolodyazhnyi
Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine,
Murmanskaya ul. 1, Kiev, 02094 Ukraine
fax: 38(044)573-2555
e-mail: olegkol321@rambler.ru
Received April 22, 2009
DOI: 10.1134/S1070363209120263
We found that reaction of dialkyl lithiummethyl-
phosphonate with nitriles in THF proceeds at low
temperature resulting in β-enaminophosphonates Ia–Id
in high yields. They are stable liquids, which are easily
distilled in a vacuum. β-Enaminephosphonates I are
prototropic forms of iminophosphonates II. However,
the tautomeric equilibrium I →← II is shifted to enamine
form I, what is unambiguously indicated by the NMR
spectra. They content clear doublet signal of PCH-
group proton and two protons of NH2-group. At the
same time β-enaminophosphonates enter easily into
the reaction with methyl ether of hydroxylamine
typical of imine compound, to form the previously un-
known β-methoxyiminophosphonates III in quantitative
1
yields [1, 2]. The H and 31P NMR spectra of com-
pounds III confirm their structure: δP values are shifted
1
to 30 ppm, and in the HMR spectra there is a doublet
signal belonging to the two protons of PCH2-group.
R'CN
(RO)2P(O)CH2Li
(RO)2P(O)CH
Ia_Id
(RO)2P(O)CH2C
NH
C
NH2
H+
R'
R'
II
[MeONH3]+ Cl _
_NH4Cl
(RO)2P(O)CH2C
R'
NOMe
IIIa, IIIc, IIId
R = Me, R' = Ph (а), R = Et, R' = C6H4F (b), R = Et, R' = Furyl (c), R = Et, R' = CF3 (d).
with anhydrous Na2SO4 and concentrated in a vacuum.
Dimethyl [(E)-2-amino-2-phenylethenyl] phos-
phonate (Ia). To a solution of dimethyl lithiumme-
thylphosphonate generated from 0.01 mol of dimethyl
methylphosphonate and 0.011 mol of butyllithium in
5 ml of THF at –80ºC was added a solution of
0.01 mol of benzonitrile in 3 ml of THF. The reaction
mixture was stirred for 3 h at this temperature. Then
the temperature was increased to +20°C, and 10 ml of
the saturated aqueous solution of NH4Cl was added.
The organic layer was separated. The water layer was
extracted with ethyl acetate. This extract was dried
Yield 75%, bp 142°C (0.045 mm Hg), Rf 0.45 (Silufol,
1
ethyl acetate). Н NMR spectrum (CDCl3), δH, ppm:
1.32 t (6H, J 6.9, CH3), 4.1 d (1H, PCH, J 12 Hz),
4.05 m (4H, OCH2), 5.9 br (2H, NH2), 7.38–7.54 m
(C6H5). 31Р NMR spectrum (CDCl3), δP, ppm: 28.8.
Found, %: N 6.20; P 13.65. C10H14NO3P. Calculated,
%: N 6.17; P 13.63.
Diethyl [(E)-2-amino-2-(4-fluorophenyl)ethenyl]
phosphonate (Ib) was prepared similarly. Yield 48%,
2703

2704
GRISHKUN, KOLODYAZHNYI
1
bp 165°C (0.03 mm Hg). Н NMR spectrum (CDCl3),
δH, ppm: 1.33 t (6H, CH3, J 7.2 Hz), 4.06 m (4H,
OCH2), 4.08 d (1Н, PCH=, J 10.2 Hz), 5.86 br (2H,
NH2), 7.07 and 7.56 m (4H, C6H4).31Р NMR spectrum
(CDCl3), δP, ppm: 25.9. 19F NMR spectrum (CDCl3),
δF, ppm: –106.2. Found, %: N 5.18; P 11.32.
C12H17FNO3P. Calculated, %: N 5.13; P 11.34.
distilled in a vacuum. Yield 75%, bp 140°C (0.05 mm Hg).
1Н NMR spectrum (CDCl3), δH, ppm: 3.46 d (2H,
PCH2, J 23.7 Hz), 3.67 d (6H, CH3O, J 11.5 Hz), 4.04
s (3H, CH3O), 7.37 m, 7.71 m (5H, C6H5). 31Р
(CDCl3), δP, ppm: 30. Found, %: N 5.40; P 12.05.
C11H16NO4P. Calculated, %: N 5.45; P 12.04.
Diethyl [(2E)-2-(2-furanyl)-2-(methoxyimine)ethyl]-
phosphonate (IIIc) was prepared similarly. Yield
Diethyl [(E)-2-amino-2-(2-furanyl)ethenyl]phos-
phonate (Ic) was prepared similarly. Yield 74%, bp
152–155°C (0.03 mm Hg), Rf 0.43 (Silufol, ethyl
1
79%, bp 132–135°C (0.045 mm Hg). Н NMR spec-
trum (CDCl3), δH, ppm: 1.25 t (6H, CH3, J 6.6 Hz),
3.35 d (1H, PCH2, J 23.1 Hz), 4.02 s (CH3O), 4.06 m
(4H, OCH2), 6.45 d. d (1H, J 1.5, J 3 Hz), 6.75 d (1H,
J 3.5 Hz), 7.46 s (1H). 31Р NMR spectrum (CDCl3), δP,
ppm: 30. Found, %: N 6.01; P 11.26. C11H18NO5P.
Calculated, %: N 5.09; P 11.25.
1
acetate). Н NMR spectrum (CDCl3), δH, ppm: 1.33 t
(6H, CH3, J 6.9 Hz), 4.06 m (4H, OCH2), 4.46 d (1H,
PCH, J 10.8 Hz), 5.98 br (2Н, NH2), 6.47 d (1H, J
3.5 Hz), 6.73 d (1Н, J 3.5 Hz), 7.46 s (1Н, furyl). 31Р
NMR spectrum (CDCl3), δP, ppm: 26.6. Found, %: N
5.74; P 12.60. C10H16 NO4P. Calculated, %: N 5.71; P
12.63.
Diethyl [(2E)-3,3,3-trifluoro-2-(methoxyimino)-
propyl]phosphonate (IIId) was prepared similarly.
1
Yield 82%, bp 118–120°C (0.04 mm Hg). Н NMR
Diethyl [(1E)-2-amino-3,3,3-trifluoro-1-propenyl]-
phosphonate (Id) was prepared similarly. Yield 50%,
spectrum (CDCl3), δH, ppm: 1.32 t (6H, CH3, J 7 Hz),
3.1 d (2H, PCH2, J 24 Hz), 4.04 s (3H, OCH3), 4.09 m
(4H, OCH2). 31Р NMR spectrum (CDCl3), δP, ppm: 30.
Found, %: N 5.16; P 11.19. C8H15F3NO4P. Calculated,
%: N 5.05; P 11.17.
1
bp 118°C (0.04 mm Hg). Н NMR spectrum (CDCl3),
δH, ppm: 1.3 t (6H, CH3, J 6.6 Hz), 3.1 d (1H, PCH,
J 24 Hz), 4.06 m (4H, OCH2), 6.14 br (2H, NH2). 31Р
NMR spectrum (CDCl3), δP, ppm: 30.64. 19F NMR
spectrum (CDCl3), δF, ppm: 106.2. Found, %: F 23.36;
N 5.61; P 12.6. C7H13F3NO3P. Calculated, %: F 23.06;
N 5.67; P 12.5.
The NMR spectra were registered on a Varian-300
spectrometer relative to internal ТМS (1Н and 13С) and
85% Н3РО4 in D2O (31Р). This work was supported by
the grant STCU no. 3558.
Dimethyl [(2E)-2-(methoxyimino)-2-phenylethyl]
phosphonate (IIIa). To a solution of 1.33 g (5 mmol)
of enamine Ia in 3 ml of anhydrous methanol was
REFERENCES
.
added a solution of 0.46 g (5.5 mmol) of MeONH2 HCl
1. Savignac, P. and Iorga, B., Modern Phosphonate
Chemistry, CRC Press, Boca Raton, Florida, 2003.
in 3 ml of anhydrous methanol at room temperature.
Then the reaction mixture was heated for 3–5 min at
80°C. The solvent was evaporated and the residue was
dissolved in ethyl acetate, filtered, concentrated, and
2. Engel, R. and Cohen, J.I., Synthesis of Carbon-
Phosphorus Bonds, CRC Press, 2003.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 12 2009