Preparation of α-ketophosphonates by oxidation of α-hydroxyphosphonates with chromium-based oxidants

Article abstract of DOI:10.1081/SCC-120030697

Various types of diethyl α-hydroxyphosphonates were efficiently converted to diethyl α-ketophosphonates by nicotinium dichromate (NDC), nicotinium chlorochromate (NCC), and isonicotinium dichromate (INDC) in high yields.

Full text of DOI:10.1081/SCC-120030697

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Preparation of α‐Ketophosphonates by Oxidation
of α‐Hydroxyphosphonates with Chromium‐Based
Oxidants
Habib Firouzabadi a , Nasser Iranpoor a & Sara Sobhani a
a Department of Chemistry, College of Sciences , Shiraz University , Shiraz, 71454, Iran
Published online: 21 Aug 2006.
To cite this article: Habib Firouzabadi , Nasser Iranpoor & Sara Sobhani (2004) Preparation of α‐Ketophosphonates by
Oxidation of α‐Hydroxyphosphonates with Chromium‐Based Oxidants, Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic Chemistry, 34:8, 1463-1471, DOI: 10.1081/SCC-120030697
To link to this article: http://dx.doi.org/10.1081/SCC-120030697
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SYNTHETIC COMMUNICATIONSw
Vol. 34, No. 8, pp. 1463–1471, 2004
Preparation of a-Ketophosphonates by
Oxidation of a-Hydroxyphosphonates
with Chromium-Based Oxidants
*
Habib Firouzabadi, Nasser Iranpoor, and
Sara Sobhani
Department of Chemistry, College of Sciences,
Shiraz University, Shiraz, Iran
ABSTRACT
Various types of diethyl a-hydroxyphosphonates were efficiently
converted to diethyl a-ketophosphonates by nicotinium dichromate
(NDC), nicotinium chlorochromate (NCC), and isonicotinium dichromate
(INDC) in high yields.
Key Words: a-Ketophosphonates; a-Hydroxyphosphonates; Chloro-
chromates; Dichromates; Oxidation.
*
Correspondence: Habib Firouzabadi, Department of Chemistry, College of Sciences,
Shiraz University, Shiraz 71454, Iran; Fax: þ98-711-2280926; E-mail: firouzabadi@
chem.susc.ac.ir.
1463
DOI: 10.1081/SCC-120030697
0039-7911 (Print); 1532-2432 (Online)
www.dekker.com
Copyright # 2004 by Marcel Dekker, Inc.

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1464
Firouzabadi, Iranpoor, and Sobhani
INTRODUCTION
Organophosphorus compounds have found wide applications in synthetic
chemistry, medicinal chemistry, and biology. Phosphonates, as a class of organo-
phosphorus compounds, are important complement to phosphates in terms of
biological activity and these aspects as well as syntheses of phosphonates have
been well documented in the literature.[1] a-Ketophosphonates constitute an
important subclass of phosphonates. The adjacent phosphoryl and carbonyl
functional groups make a-ketophosphonates interesting compounds as
potential precursors in organic synthesis.[2] For instance, it is possible to
convert them to a,a-difluorophosphonates[3] and oximes,[4] to reduce enantio-
selectively to the corresponding a-hydroxyphosphonates,[5] and to use them in
the hetero Diels–Alder[6] and the Wittig reactions.[7] It is also a very well
known fact that the carbon–phosphorus bond in a-ketophosphonates is
readily cleaved as a result of nucleophilic attack.[8] This property makes a-
ketophosphonates potentially useful acylating agents, but also susceptible to
hydrolysis and difficult to handle.[8]
The Michael–Arbuzov reaction is a general method for the preparation of
these compounds from acyl chlorides and trialkylphosphites.[9] This method
works well for simple acyl chlorides but it is less successful for preparation
of a-keto-b,g-unsaturated phosphonates, where multiple addition products
were often observed.[9] Another method which has rarely been used for the
preparation of these compounds is the oxidation of a-hydroxyphospho-
nates.[10] A literature survey shows that in contrast to the large number of
existing methods for conversion of alcohols to carbonyl compounds, few
methods are known for the preparation of diethyl a-ketophosphonates from
the corresponding diethyl a-hydroxyphosphonates. Oxidation by known
reagents such as CrO3, MnO2, CrO3/Al2O3, and Pfitzner–Moffatt oxidation
condition require long reaction times, high molar ratio of an oxidant/
substrate, or special treatment for activation of the reagents.[3,11]
In recent years, we have reported new and efficient methods for the prep-
aration of diethyl a-functionalized phosphonates from diethyl a-hydroxyphos-
phonates.[12]
In continuation of our interests for preparation of diethyl a-ketophospho-
nates 2, now we report successful and highly efficient oxidation of various
types of diethyl a-hydroxyphosphonates 1 by nicotinium dichromate
(NDC),[13] nicotinium chlorochromate (NCC),[14] and isonicotinium dichromate
(INDC)[15] in dry and refluxing CH3CN (Sch. 1 and Table 1). Fortunately, the
cleavage of the C(O)–P bond in the presence of these oxidants has not been
observed which constitutes a strong merit of the presented protocol.
As shown in Table 1, diethyl a-hydroxy-(phenylmethyl)phosphonates with
different substituents onthe phenylgroup (1a–k), diethyl a-hydroxy-2-naphthyl,

ORDER
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a-Ketophosphonates Preparation by Oxidation
1465
Scheme 1.
3-pyridyl, and also b,g-unsaturated phosphonates (1l–o) were easily converted
to the corresponding diethyl a-ketophosphonates (2a–o) in the presence of
NDC, INDC, or NCC in 88–99%, 85–98%, and 87–98% yields, respectively.
We have observed that the oxidants such as PCC[16] and PDC[17] also
worked efficiently but suffered from a troublesome workup such as vacuum
distillation for isolation of a-ketophosphonates from pyridine, which is
present in the reaction medium. We have also observed that the acidic
work-up in those cases was always accompanied by the extensive cleavage
Table 1. Oxidation of a-hydroxyphosphonates 1 to a-ketophosphonates 2 by NDC,
INDC, and NCC in refluxing CH3CN.
NDC
INDC
NCC
Time Yielda Time Yielda Time Yielda
Product 2
R-
(min)
(%)
(min)
(%)
(min)
(%)
a
b
c
d
e
f
C6H5–
5
15
5
99
90
94
95
97
98
95
99
90
91
90
91
97
95
88
30
30
25
40
20
25
15
20
45
50
40
35
25
15
45
97
96
94
90
95
94
95
98
89
90
87
87
96
95
85
5
10
15
30
50
60
45
40
35
45
30
40
15
20
50
98
93
90
88
87
89
93
92
91
88
90
87
96
90
87
4-CH3C6H4–
4-CH3OC6H4–
2,4,6-(CH3)3C6H2–
2-ClC6H4–
5
20
20
25
5
3-ClC6H4–
4-ClC6H4–
g
h
i
2,6-Cl2C6H3–
2-O2NC6H4–
3-O2NC6H4–
4-O2NC6H4–
2-Naphthyl
40
50
40
30
15
10
25
j
k
l
m
n
o
3-Pyridyl
PhCH55CH–
CH3CH55CH–
aOxidant/substrate ¼ 1/1, isolated yields. All of the products gave satisfactory spec-
tral data compared with authentic samples.

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1466
Firouzabadi, Iranpoor, and Sobhani
of the C(O)–P bond. Similar oxidations conducted in the presence of NDC,
INDC, or NCC produced solid mixtures of chromium(III) residues (green)
accompanied by nicotinic or isonicotinic acids which were simply isolated
by filtration. Evaporation of the solvent produced the desired a-ketophospho-
nates 2 in high yields and purities.
In conclusion, in this report we applied NDC, NCC, INDC as efficient
oxidizing agents for the facile preparation of diethyl a-ketophosphonates by
direct oxidation of diethyl a-hydroxyphosphonates. The absence of by-
products due to the cleavage of the C(O)–P bond, the use of equimolar
amounts of the oxidants and the simple work-up of reaction mixtures are
the advantages of the presented protocol.
EXPERIMENTAL
Chemicals were either prepared in our laboratories or were purchased
from Fluka and Merck Chemical Companies. NDC, NCC, INDC were
prepared according to the reported procedures.[14,15] Products were purified
by plate chromatography. The purity determination of the products was
accomplished by TLC on silica gel polygram SIL G/UV 254 plates. Mass
spectra were run on a Shimadzu GC-Mass-QP 1000 EX at 70 eV. The IR spec-
tra were recorded on a Shimadzu Fourier Transform Infrared Spectropho-
tometer (FT-IR-8300). The NMR spectra were recorded on a Bruker
advance DPX 250 MHz spectrometer.
Preparation of Diethyl a-Ketophosphonates by the Oxidation
of Diethyl a-Hydroxyphosphonates (General Procedure)
To a solution of diethyl a-hydroxyphosphonate (5 mmol) in dry CH3CN
(50 mL), the oxidant (5 mmol) was added and the resulting mixture was stirred
under reflux for the time given in Table 1. The resulting heterogeneous reac-
tion mixture was then filtered and the filter cake was washed with CCl4
(4 ꢀ 25 mL). Evaporation of the solvent afforded an oily material containing
a crude 2, contaminated with the tiny amounts of white solid residues of
nicotinic or isonicotinic acids. Further purification was proceeded by dissol-
ution of the crude product in CCl4 (25 mL), filtration, and distillation. All
compounds gave satisfactory spectral data compared with authentic samples.
The following compounds were obtained:
Diethyl benzoyl phosphonate (2a). B.p. 125–1268C/0.05 mmHg
1
(lit.[2a] b.p. 106–1098C/0.01 mmHg); H NMR (CDCl3, TMS): d 1.37–1.68
2
2
(t, 6H, JHH ¼ 7.1 Hz, 2-OCH2CH3), 4.08–4.28 (dq, 4H, JPH ¼ 7.1 Hz,

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a-Ketophosphonates Preparation by Oxidation
1467
2JHH ¼ 7.1 Hz, 2-OCH2CH3), 7.28–7.6 (m, 3H), 8.03–8.25 (m, 2H) ppm; 13
C
3
NMR (CDCl3, TMS): 16.64 (d, JCP ¼ 5.7 Hz, 2-OCH2CH3), 64.31
2
(d, JCP ¼ 7.5 Hz, 2-OCH2CH3), 129.15, 130.06, 135.03, 136.29 (–C6H5),
1
199.12 (d, JCP ¼ 177.5 Hz, C55O) ppm; IR (neat): n 1650 (C55O), 1267
(P55O) cm21; MS: Mþ (242), M–P(O)(OEt)2 (105); Elemental analysis for
C11H15O4P requires C 54.5%, H 6.2%; found: C 54.2%, H 6.0%.
Diethyl 4-methyl-benzoyl phosphonate (2b). B.p. 130–1318C/
1
0.05 mmHg (lit.[2a] b.p. 116–1178C/0.03 mmHg); H NMR (CDCl3, TMS):
2
d 1.29–1.42 (t, 6H, JHH ¼ 7.1 Hz, 2-OCH2CH3), 2.35 (s, 3H, –CH3),
2
2
4.11–4.16 (dq, 4H, JPH ¼ 7.1 Hz, JHH ¼ 7.1 Hz, 2-OCH2CH3), 7.12–7.21
(m, 2H), 8.04–8.07 (m, 2H) ppm; 13C NMR (CDCl3, TMS): 16.67
3
2
(d, JCP ¼ 5.7 Hz, 2-OCH2CH3), 22.18 (–CH3), 64.24 (d, JCP ¼ 7.5 Hz,
2-OCH2CH3), 127.35, 129.89, 130.31, 146.41 (–C6H4), 198.46
1
(d, JCP ¼ 176.6 Hz, C55O) ppm; IR (neat): n 1650 (C55O), 1261 (P55O)
cm21; MS: Mþ (256), M–P(O)(OEt)2 (119); Elemental analysis for
C12H17O4P requires C 56.2%, H 6.6%; found: C 56.0%, H 6.1%.
Diethyl 4-methoxy-benzoyl phosphonate (2c). B.p. 166–1678C/
0.05 mmHg (lit.[2a] b.p. 175–1798C/1.5 mmHg); H NMR (CDCl3, TMS): d
1
2
1.11–1.29 (t, 6H, JHH ¼ 7.1 Hz, 2-OCH2CH3), 3.80 (s, 3H, –CH3), 3.90–
2
2
4.10 (dq, 4H, JPH ¼ 7.1 Hz, JHH ¼ 7.1 Hz, 2-OCH2CH3), 6.84–6.90
(m, 2H), 7.42–7.50 (m, 2H) ppm; 13C NMR (CDCl3, TMS): 16.75
3
2
(d, JCP ¼ 5.7 Hz, 2-OCH2CH3), 55.59 (–CH3), 63.46 (d, JCP ¼ 7.5 Hz,
2-OCH2CH3), 114.03, 128.82, 129.21, 159.78 (–C6H4), 198.01
1
(d, JCP ¼ 176.2 Hz, C55O) ppm; IR (neat): n 1655 (C55O), 1265 (P55O)
cm21; MS: Mþ (272), M–P(O)(OEt)2 (135); Elemental analysis for
C12H17O5P requires C 52.9%, H 6.2%; found: C 52.2%, H 5.9%.
Diethyl 2,4,6-trimethyl-benzoyl phosphonate (2d). B.p. 108–1098C/
0.07 mmHg (lit.[2a] b.p. 131–1328C/0.3 mmHg);1H NMR (CDCl3, TMS): d
2
1.25–1.32 (t, 6H, JHH ¼ 7.1 Hz, 2-OCH2CH3), 2.23 (s, 6H, 2,6-diCH3),
2
2
2.27 (s, 3H, 4-CH3), 4.06–4.17 (dq, 4H, JPH ¼ 7.1 Hz, JHH ¼ 7.1 Hz,
2-OCH2CH3), 6.83 (s, 2H) ppm; 13C NMR (CDCl3, TMS): 16.81
3
(d, JCP ¼ 5.7 Hz, 2-OCH2CH3), 21.17 (2,6-diCH3), 21.38 (4-CH3), 63.12
2
(d, JCP ¼ 7.5 Hz, 2-OCH2CH3), 129.74, 130.3, 137.69, 137.75 (–C6H2),
1
199.01 (d, JCP ¼ 177.0 Hz, C55O) ppm; IR (neat): n 1665 (C55O), 1250
(P55O) cm21; MS: Mþ (284), M–P(O)(OEt)2 (142); Elemental analysis for
C14H21O4P requires C 59.1%, H 7.4%; found: C 59.3%, H 7.6%.
Diethyl 2-chloro-benzoyl phosphonate (2e). B.p. 105–1068C/
1
0.05 mmHg (lit.[18] b.p. 158–1608C, 2.3 mmHg); H NMR (CDCl3, TMS):
2
d
1.58 (t, 6H, JHH ¼ 7.1 Hz, 2-OCH2CH3), 4.17–4.30 (m, 4H,
2-OCH2CH3), 7.24–7.44 (m, 3H), 8.14–8.20 (m, 1H) ppm; 13C NMR (CDCl3,
3
2
TMS): 16.65 (d, JCP ¼ 5.7 Hz, 2-OCH2CH3), 64.82 (d, JCP ¼ 7.4
Hz, 2-OCH2CH3), 126.84, 127.10, 130.64–132.07, 132.68–133.85,

ORDER
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1468
Firouzabadi, Iranpoor, and Sobhani
134.16–135.98 (–C6H4), 200.53 (d, 1JCP ¼ 182.0 Hz, C55O) ppm; IR (neat):
n 1650 (C55O), 1245 (P55O) cm21; MS: Mþ (276), M þ 2 (279),
M–P(O)(OEt)2 (139); Elemental analysis for C11H14ClO4P requires C
47.8%, H 5.1%; found: C 47.5%, H 4.9%.
Diethyl 3-chloro-benzoyl phosphonate (2f). B.p. ¼ 101–1028C/
0.06 mmHg (lit.[19] b.p. 1278C/0.4 mmHg); 1H NMR (CDCl3, TMS): d
1.28–1.34 (m, 6H, 2-OCH2CH3), 4.16–4.27 (m, 4H, 2-OCH2CH3), 7.22–
7.53 (m, 3H), 7.96 (s, 1H) ppm; 13C NMR (CDCl3, TMS): 18.44
3
2
(d, JCP ¼ 5.7 Hz, 2-OCH2CH3), 66.45 (d, JCP ¼ 7.4 Hz, 2-OCH2CH3),
1
130.15–139.50 (–C6H4), 201.46 (d, JCP ¼ 182.0 Hz, C55O) ppm; IR
(neat): n 1650 (C55O), 1267 (P55O) cm21; MS: Mþ (276), M þ 2 (279),
M–P(O)(OEt)2 (139); Elemental analysis for C11H14ClO4P requires C
47.8%, H 5.1%; found: C 47.4%, H 4.7%.
Diethyl 4-chloro-benzoyl phosphonate (2g). B.p. 142–1438C/
1
0.06 mmHg (lit.[2a] b.p. 112–1138C/0.01 mmHg); H NMR (CDCl3, TMS):
2
d 1.13–1.42 (t, 6H, JHH ¼ 7.1 Hz, 2-OCH2CH3), 4.15–4.33 (dq, 4H,
2
2JPH ¼ 7.1 Hz, JHH ¼ 7.1 Hz, 2-OCH2CH3), 7.47–7.50 (m, 2H), 8.21–8.24
3
(m, 2H) ppm; 13C NMR (CDCl3, TMS): 16.75 (d, JCP ¼ 5.7 Hz,
2
2-OCH2CH3), 64.49 (d, JCP ¼ 7.5 Hz, 2-OCH2CH3), 129.62, 131.58,
1
133.72, 141.85 (–C6H4), 198.09 (d, JCP ¼ 180.0 Hz, C55O) ppm; IR
(neat): n 1650 (C55O), 1260 (P55O) cm21; MS: Mþ (277), M þ 2 (279),
M–P(O)(OEt)2 (139); Elemental analysis for C11H14ClO4P requires C
47.8%, H 5.1%; found: C 47.9%, H 5.3%.
Diethyl 2,6-dichloro-benzoyl phosphonate (2h). B.p. 150–1518C/
1
2
0.05 mmHg; H NMR (CDCl3, TMS): d 1.04–1.24 (t, 6H, JHH ¼ 7.1 Hz,
2-OCH2CH3), 3.95–4.23 (dq, 4H, 2JPH ¼ 7.1 Hz, 2JHH ¼ 7.1 Hz,
2-OCH2CH3), 6.90–7.09 (m, 3H) ppm; 13C NMR (CDCl3, TMS): 16.61
3
2
(d, JCP ¼ 5.7 Hz, 2-OCH2CH3), 64.85 (d, JCP ¼ 7.5 Hz, 2-OCH2CH3),
1
128.06, 128.56, 131.51, 132.07 (–C6H3), 204.36 (d, JCP ¼ 195.5 Hz,
C55O) ppm; IR (neat): n 1691 (C55O), 1264 (P55O) cm21; MS: Mþ (311),
M þ 2 (313), M þ 4 (315), M–P(O)(OEt)2 (174); Elemental analysis for
C11H13Cl2O4P requires C 42.4%, H, 4.2%; found: C 42.0%, H 4.0%.
Diethyl 2-nitro-benzoyl phosphonate (2i).a B.p. 146–1478C/
0.05 mmHg; 1H NMR (CDCl3, TMS): d 1.34 (t, 6H, JHH ¼ 7.0 Hz,
2
2-OCH2CH3), 4.20–4.32 (dq, 4H, 2JPH ¼ 7.2 Hz, 2JHH ¼ 7.3 Hz,
2
2-OCH2CH3), 7.4 (d, 1H, JHH ¼ 7.4 Hz), 7.70–7.85 (m, 2H), 8.44 (d, 1H,
2JHH ¼ 7.7 Hz,) ppm; 13C NMR (CDCl3, TMS): 16.64 (d, JCP ¼ 5.7 Hz,
3
aCompounds 2i, 2j, and 2n are known compounds and they are reported in the litera-
ture.[11b] Physical and analytical data are not reported for any of them.

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a-Ketophosphonates Preparation by Oxidation
1469
2
2-OCH2CH3), 64.92 (d, JCP ¼ 7.2 Hz, 2-OCH2CH3), 123.92, 124.48,
128.56–130.44, 131.93–132.88, 136.24, 147.08 (–C6H4), 203.86
1
(d, JCP ¼ 180.0 Hz, C55O) ppm; IR (neat): n 1655 (C55O), 1260 (P55O)
cm21; MS: Mþ (287), M–P(O)(OEt)2 (150); Elemental analysis for
C11H14NO6P requires C 46.0%, H 4.9%; found: C 46.3%, H 5.3%.
Diethyl 3-nitro-benzoyl phosphonate (2j). B.p. 149–1508C/0.05mmHg;
1H NMR (CDCl3, TMS): d 1.15–1.43 (m, 6H, 2-OCH2CH3), 4.10–4.20 (q, 2H,
2JHH ¼ 7.1 Hz, 2-OCH2CH3), 4.30–4.39 (q, 2H, 2JHH ¼ 7.1 Hz, 2-OCH2CH3),
8.44–8.48 (m, 2H), 8.59–8.62 (m, 1H), 8.84 (s, 1H) ppm; 13C NMR (CDCl3,
3
2
TMS): 16.63 (d, JCP ¼ 5.5 Hz, 2-OCH2CH3), 65.12 (d, JCP ¼ 7.5 Hz,
2-OCH2CH3), 129.04, 129.94, 130.64, 132.74, 135.71–137.33, 167.0
1
(–C6H4), 197.75 (d, JCP ¼ 183.4 Hz, C55O) ppm; IR (neat): n 1650 (C55O),
1260 (P55O) cm21; MS: Mþ (287), M–P(O)(OEt)2 (150); Elemental analysis
for C11H14NO6P requires C 46.0%; H 4.9%; found: C 45.8%, H 4.6%.
Diethyl 4-nitro-benzoyl phosphonate (2k). M.p. 140–1418C (lit.[20] M.p.
1
142–1438C); H NMR (CDCl3, TMS): d 1.23–1.321 (m, 6H, 2-OCH2CH3),
2
4.00–4.18 (m, 2H, 2-OCH2CH3), 7.66 (d, 2H, JHH ¼ 7.5 Hz), 8.7 (d, 2H,
2JHH ¼ 8.7 Hz) ppm; IR (KBr): n 1650 (C55O), 1260 (P55O) cm21; MS: Mþ
(287), M–P(O)(OEt)2 (150); Elemental analysis for C11H14NO6P requires C
46.0%, H 4.9%; found: C 46.4%, H 5.2%.
Diethyl 2-naphthoyl phosphonate (2l). B.p. 152–1538C/0.07 mmHg
(lit.[18] b.p. 188–1918C/1.2 mmHg); 1H NMR (CDCl3, TMS): d 11.33–
1.44 (m, 6H, 2-OCH2CH3), 4.28–4.39 (m, 4H, 2-OCH2CH3), 7.57–7.64
(m, 2H), 7.85–7.93 (m, 2H), 8.04–8.14 (m, 2H), 9.08 (s, 1H) ppm; 13C
3
NMR (CDCl3, TMS): 16.79 (d, JCP ¼ 5.7 Hz, 2-OCH2CH3), 64.52
2
(d, JCP ¼ 7.3 Hz, 2-OCH2CH3), 123.75–136.67, 169.90 (C10H7), 199.07
1
(d, JCP ¼ 174.9 Hz, C55O) ppm; IR (neat): n 1655 (C55O), 1260 (P55O)
cm21; MS: Mþ (292), M–P(O)(OEt)2 (155); Elemental analysis for
C15H17O4P requires C 61.6%, H 5.8%; found: C 61.2%, H 5.3%.
Diethyl 3-pridoyl phosphonate (2m). B.p. 125–1268C/2 mmHg (lit.[21]
b.p. 1288C/2 mmHg); 1H NMR (CDCl3, TMS): d 1.23–1.36 (m, 6H,
2-OCH2CH3), 4.14–4.30 (m, 4H, 2-OCH2CH3), 7.38–7.43 (m, 1H), 7.90
2
2
(d, 2H, JHH ¼ 7.9 Hz), 8.78 (d, 2H, JHH ¼ 3.8 Hz), 9.34 (s, 1H) ppm; 13C
3
NMR (CDCl3, TMS): 16.72 (d, JCP ¼ 5.5 Hz, 2-OCH2CH3), 64.72
2
(d, JCP ¼ 7.5 Hz, 2-OCH2CH3), 124.11, 131.96, 151.27, 154.90 (C5H4N),
1
199.18 (d, JCP ¼ 183.5 Hz, C55O) ppm; IR (neat): n 1654 (C55O), 1245
(P55O) cm21; MS: Mþ (243), M–P(O)(OEt)2 (106); Elemental analysis for
C10H14NO4P requires C 49.4%, H 5.8%; found: C 49.0%, H 5.4%.
Diethyl 1-oxo-3-phenyl-2-propenylphosphonate (2n). B.p. 108–
1
2
1098C/0.05 mmHg; H NMR (CDCl3, TMS): d 1.30 (t, 6H, JHH ¼ 7.1 Hz,
2
2
2-OCH2CH3), 4.14 (dq, 4H, JPH ¼ 7.1 Hz, JHH ¼ 7.1 Hz, 2-OCH2CH3),
7.38–7.43 (m, 1H), 8.45–8.48 (m, 1H), 8.77–8.78 (m, 1H), 9.34 (s, 1H)

ORDER
REPRINTS
1470
Firouzabadi, Iranpoor, and Sobhani
ppm; 13C NMR (CDCl3, TMS): 16.72 (d, 3JCP ¼ 5.7 Hz, 2-OCH2CH3), 64.72
2
(d, JCP ¼ 7.5 Hz, 2-OCH2CH3), 124.11, 137.34, 151.27, 154.90 (–C5H5N),
1
199.18 (d, JCP ¼ 195.5 Hz, C55O) ppm; IR (neat): n 1655 (C55O), 1260
(P55O) cm21; MS: Mþ (268), M–P(O)(OEt)2 (131); Elemental analysis for
C13H17O4P requires C 58.2%, H 6.3%; found: C 58.0%, H 6.1%.
Diethyl 1-oxo-2-butenylphosphonate (2o). B.p. 1058C/10 mmHg;
(lit.[2d] b.p. 1098C/10 mmHg); 1H NMR (CDCl3, TMS): d 1.18–1.33
(m, 6H, 2-OCH2CH3), 1.90–1.96 (m, 3H, CH3), 4.02–4.20 (m, 4H,
2-OCH2CH3), 6.27–6.42 (m, 1H), 7.38–7.53 (m, 1H) ppm; 13C NMR
3
(CDCl3, TMS): 16.71 (d, JCP ¼ 5.5 Hz, 2-OCH2CH3), 18.18 (CH3), 63.14
2
(d, JCP ¼ 7.3 Hz, 2-OCH2CH3), 126.10, 129.78 (CH55CH), 198.08
1
(d, JCP ¼ 189.5 Hz, C55O) ppm; IR (neat): n 1665 (C55O), 1265 (P55O)
cm21; MS: Mþ (206), M–P(O)(OEt)2 (69); Elemental analysis for
C8H15O4P requires C 46.46%, H 7.3%; found: C 46.41%, H 7.1%.
ACKNOWLEDGMENT
We are thankful to Dr. H. Mousavipour and F. Pirhadi for their assistance
and the Shiraz University Research Council for the partial support of this
work.
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Received in Poland August 18, 2003

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