N. S. Goulioukina et al. / Tetrahedron: Asymmetry 12 (2001) 319–327
325
(dd, 2JHH3 =1.3 Hz, 3JPH=21.6 Hz, 1H, cis-PCꢁCH),
thylethenylphosphonic acid 1c (1.22 g, 5.2 mmol),
HCOONH4 (1.98 g, 31 mmol) and Pd/C (5%, 0.31 g) in
water (40 mL). Pale cream solid, mp 181–182°C. 31P
3
6.84 (d, JAB=8.8 Hz, 2H, arom.), 7.45 (dd, JAB=8.8
Hz, 2H, arom.). IR (film): w=2985, 1610, 1520, 1300,
1260, 1185, 1040, 970, 845, 800 cm−1.
NMR (CD3OD): l 28.6. H NMR (CD3OD): l 1.71
1
3
3
(dd, JHH=7.4 Hz, JPH=17.8 Hz, 3H, CH3), 4.14 (dq,
2
1-(6-Methoxy-2-naphthyl)ethenylphosphonate 2f was
prepared in 74% yield analogously to 2a from 2-eth-
ynyl-6-methoxynaphthalene (0.64 g, 3.5 mmol),
HP(O)(OEt)2 (0.45 mL, 3.5 mmol), Pd2(dba)3·CHCl3
(54.4 mg, 53 mmol) and PPh3 (110 mg, 0.42 mmol) in
THF (3.5 mL). After evaporation of the solvent, the
residue was purified by chromatography on silica gel
(Chemapol, L 5/40). PPh3 and dibenzylideneacetone
were eluted with benzene and diethyl ether then 2e was
eluted with ethyl acetate. Evaporation of the product
fractions afforded a reddish oil, Rf 0.2 (Silufol, Et2O).
3JHH=7.4 Hz, JPH=22.8 Hz, 1H, CH), 5.48 (s, OH),
7.4–7.6 (m, 3H, arom.), 7.7–7.8 (m, 2H, arom.), 7.86 (d,
3
3JHH=8.0 Hz, 1H, arom.), 8.19 (d, JHH=8.0 Hz, 1H,
arom.). IR (Nujol): w=2700 v.br., 2230 v.br., 1520,
1130, 990, 935, 800, 780 cm−1. Anal. calcd for
C12H13O3P: C, 61.02; H, 5.55; P, 13.11. Found: C,
60.96; H, 5.42; P, 13.00%.
4.6. Reduction of diethyl 1-phenylethenylphosphonate
2a. Typical procedure
1
31P NMR (CH3OH): l 17.0. H NMR (CDCl3): l 1.28
A mixture of 2a (1.20 g, 5 mmol), ammonium formate
(1.91 g, 30 mmol) and palladium on carbon (5%, 0.29 g)
in 70 mL of MeOH was heated to reflux for 3 h under
argon atmosphere. The catalyst was filtered off using a
short pad of silica gel. The reaction mixture was evapo-
rated to dryness in vacuo. The residue was extracted
with Et2O and the combined organic layers were
washed with water, dried (MgSO4), filtered and evapo-
rated. The pale yellow oil thus obtained was distilled to
give diethyl 1-phenylethylphosphonate 4a as a color-
less viscous liquid (1.05 g, 87%), bp 90–92°/10−1
mmHg.6b,c,11c 31P NMR (CH3OH): l 30.2. 1H NMR
3
(t, JHH=7.2 Hz, 6H, CH2CH3), 3.92 (s, 3H, OCH3),
2
3
4.12 (m, 4H, CH2CH3), 6.25 (dd, JHH=1.5 Hz, JPH
=
2
45.8 Hz, 1H, trans-PCꢁCH), 6.37 (dd, JHH=1.5 Hz,
3JPH=21.9 Hz, 1H, cis-PCꢁCH), 7.1–7.2 (m, 2H,
arom.), 7.6–7.8 (m, 3H, arom.), 7.98 (s, 1H, arom.). IR
(film): w=2990, 1635, 1610, 1490, 1395, 1265, 1170,
1040, 970, 860, 810, 760 cm−1.
4.5. Reduction of 1-phenylethenylphosphonic acid 1a.
Typical procedure
3
A mixture of 1a (0.92 g, 5 mmol), ammonium formate
(1.90 g, 30 mmol) and palladium on carbon (5%, 0.30 g)
in MeOH (70 mL) was heated under reflux for 4 h
under argon. The mixture was filtered through a short
pad of silica gel. Methanol was removed from the
filtrate in vacuo. The residue was acidified with conc.
HCl (ca. 1 mL) and extracted with AcOEt. The com-
bined organic layers were dried (MgSO4), filtered and
evaporated in vacuo to furnish a pale yellow oil.
Recrystallization from benzene/petroleum ether
afforded 1-phenylethylphosphonic acid 3a as a white
solid (0.65 g, 70%), mp 151°C.6a 31P NMR (EtOAc): l
(CDCl3): l 1.13 (t, JHH=7.1 Hz, 3H, CH2CH3), 1.26
3
3
(t, JHH=7.1 Hz, 3H, CH2CH3), 1.57 (dd, JHH=7.4
3
3
Hz, JPH=18.5 Hz, 3H, CHCH3), 3.17 (dq, JHH=7.4
Hz, JPH=22.6 Hz, 1H, CH), 3.78 (m, 1H, CH2CH3),
2
3.92 (m, 1H, CH2CH3), 4.02 (m, 2H, CH2CH3), 7.20–
7.35 (m, 5H, arom.). IR (film): w=2985, 2935, 1500,
1460, 1395, 1250, 1165, 1030, 965, 810, 770, 705 cm−1.
Diethyl 1-(4-methoxyphenyl)ethylphosphonate 4e was
prepared in 88% yield analogously to 4a from diethyl
1-(4-methoxyphenyl)ethenylphosphonate 2e (0.72 g, 2.7
mmol), HCOONH4 (1.27 g, 20 mmol) and Pd/C (5%,
0.28g) in MeOH (40 mL). Reaction time was 10 h.
Compound 4e was isolated as a colorless viscous liquid,
bp 137–141°C/10−1 mmHg. 31P NMR (CH3OH): l 30.6.
1H NMR (CDCl3): l 1.14 (t, 3JHH=7.0 Hz, 3H,
1
3
31.0. H NMR (CD3OD): l 1.59 (dd, JHH=7.6 Hz,
3JPH=18.0 Hz, 3H, CH3), 3.18 (dq, 3JHH=7.6 Hz,
2JPH=22.6 Hz, 1H, CH), 4.95 (s, OH), 7.20–7.40 (m,
1+2+2H, arom.). IR (Nujol): w=2700 v.br., 2350 v.br.,
1500, 1175, 1005, 940, 775, 700 cm−1.
3
CH2CH3), 1.26 (t, JHH=7.0 Hz, 3H, CH2CH3), 1.53
3
3
(dd, JHH=7.4 Hz, JPH=18.5 Hz, 3H, CHCH3), 3.11
3
2
1-(4-Methylphenyl)ethylphosphonic acid 3b was pre-
pared in 87% yield analogously to 3a from 1-(4-
methylphenyl)ethenylphosphonic acid 1b (0.99 g, 5
mmol), HCOONH4 (1.90 g, 30 mmol) and Pd/C (5%,
0.30 g) in MeOH (70 mL). Pale cream solid, mp 129–
(dq, JHH=7.4 Hz, JPH=22.5 Hz, 1H, CH), 3.78 (s,
3H, OCH3), 3.79 (m, 1H, CH2CH3), 3.90 (m, 1H,
3
CH2CH3), 4.01 (m, 2H, CH2CH3), 6.85 (d, JAB=8.7
Hz, 2H, arom.), 7.10 (d, JAB=8.7 Hz, 2H, arom.). IR
3
(film): w=2990, 2940, 1520, 1470, 1300, 1250, 1180,
1030, 960, 840, 785 cm−1. Anal. calcd for C13H21O4P: C,
57.35; H, 7.77; P, 11.38. Found: C, 57.26; H, 8.05; P,
11.12%.
130°C. 31P NMR (CD3OD):
(CD3OD): l 1.52 (dd, JHH=7.0 Hz, JPH=17.9 Hz,
l
27.9. 1H NMR
3
3
3
3H, CHCH3), 2.28 (s, 3H, CH3C6H4), 3.08 (dq, JHH
=
2
7.0 Hz, JPH=22.1 Hz, 1H, CH), 5.13 (s, OH), 7.09 (d,
3JAB=7.6 Hz, 2H, arom.), 7.21 (d, JAB=7.6 Hz, 2H,
Diethyl 1-(6-methoxy-2-naphthyl)ethylphosphonate 4f
was prepared in 88% yield analogously to 4a from
1-(6-methoxyl-2-naphthyl)ethenylphosphonate 2f (0.72
g, 2.3 mmol), HCOONH4 (1.06 g, 16.9 mmol) and Pd/C
(5%, 0.24g) in 34 mL of MeOH. Reaction time 10 h.
3
arom.). IR (Nujol): w=2700 v.br., 2270 v.br., 1520,
1205, 1005, 950, 825, 730 cm−1. Anal. calcd for
C9H13O3P: C, 54.00; H, 6.55; P, 15.47. Found: C, 53.81;
H, 6.64; P, 15.24%.
1
Pale yellow oil. 31P NMR (CH3OH): l 30.0. H NMR
3
1-(1-Naphthyl)ethylphosphonic acid 3c was prepared in
74% yield analogously to 3a from 1-naph-
(CDCl3): l 1.06 (t, JHH=7.0 Hz, 3H, CH2CH3), 1.22
3
3
(t, JHH=7.0 Hz, 3H, CH2CH3), 1.61 (dd, JHH=7.2