Knoevenagel reaction of diethylphosphonoacetic acid: A facile route to diethyl (E)-2-arylvinylphosphonates

Article abstract of DOI:10.1055/s-2005-918406

Knoevenagel reaction of aromatic aldehydes or α-substituted aliphatic aldehydes with diethylphosphonoacetic acid leads to the formation of 3-substituted-2-(diethoxyphosphoryl)acrylic acids. Decarboxylation of the resulting (E)-3-aryl-2-(diethoxyphosphoryl)acrylic acids afforded diethyl (E)-2-arylvinylphosphonates. Direct synthesis of diethyl vinylphosphonates from some aromatic aldehydes and formaldehyde is also reported. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2005-918406

PAPER
2887
Knoevenagel Reaction of Diethylphosphonoacetic Acid: A Facile Route to
Diethyl (E)-2-Arylvinylphosphonates
K
noevenage
l
Rea
c
e
tion of
D
ie
n
thylphosphon
r
oacetic
yAcid k Krawczyk,* Łukasz Albrecht
Institute of Organic Chemistry, Technical University, Żeromskiego 116, 90-924 Łódź, Poland
Fax +48(42)6365530; E-mail: henkrawc@p.lodz.pl
Received 26 April 2005; revised 13 June 2005
there is still a great need for cheaper methods using more
accessible starting materials.
Abstract: Knoevenagel reaction of aromatic aldehydes or a-substi-
tuted aliphatic aldehydes with diethylphosphonoacetic acid leads to
the formation of 3-substituted-2-(diethoxyphosphoryl)acrylic acids.
Decarboxylation of the resulting (E)-3-aryl-2-(diethoxyphosphor-
yl)acrylic acids afforded diethyl (E)-2-arylvinylphosphonates. Di-
rect synthesis of diethyl vinylphosphonates from some aromatic
aldehydes and formaldehyde is also reported.
Recently, we have been exploring the condensations of di-
ethylphosphonoacetic acid (1) with formaldehyde as an
effective route to 1-(aminomethyl)vinylphosphonates,11
1-(alkoxymethyl)vinylphosphonates12 and dicyclohexyl-
ammonium 2-(diethoxyphosphoryl)acrylate.13 Among
others, we have found that a mixture of b-alanine and
AcOH is a versatile catalyst for the Knoevenagel reaction
of the acid 1 with isobutyraldehyde (2j) producing (E,Z)-
2-diethoxyphosphoryl-4-methyl-2-pentenoic acid (3j).12
Key words, Knoevenagel reaction, vinylphosphonates, decarboxy-
lation, acrylic acids, diethylphosphonoacetic acid
Sequential Knoevenagel condensation of acetic acids
bearing different electron-withdrawing groups at C-2 with
carbonyl compounds and decarboxylation of the resulting
2-alkenoic acids is a versatile and generally used synthetic
approach to the corresponding functionalized olefins.
Within this area, the use of malonic acid, malonic mo-
noesters and cyanoacetic acid for carboxyolefination of
aldehydes and ketones leading to 2-alkenoic acids, 2-al-
kenoates and related cyanides, respectively, is well docu-
mented.1 Surprisingly, phosphonoolefination of carbonyl
compounds with dialkylphosphonoacetic acids to give
a,b-unsaturated phosphonates remains unexplored.
In this paper we demonstrate that such a type of conden-
sation has general applicability and can be treated as a
convenient source of differently substituted 2-(diethoxy-
phosphoryl)acrylic acids 3. Moreover, we show that the
novel condensation together with subsequent decarboxy-
lation of the acids 3 constitutes particularly advantageous
and atom economic approach to (E)-2-arylvinylphospho-
nates. Additionally, direct phosphonoolefination of some
aromatic aldehydes and formaldehyde with the acid 1 is
described.
We began our investigations with the goal of finding the
most suitable conditions for the preparation of acrylic ac-
ids 3. Various aliphatic and aromatic aldehydes were re-
acted with the acid 1 in boiling benzene in the presence of
b-alanine (10 mol%) and AcOH (27 mol%) with azeotro-
pic removal of water (Scheme 1).
For the past several years there has been considerable in-
terest in the stereoselective synthesis of diethyl 1-alke-
nylphosphonates due to their use as versatile
intermediates both in the synthesis of highly functional-
ized organophosphorus and organic compounds.2 A num-
ber of synthetic approaches have been reported for this
class of phosphonates. They are readily available by Hor-
ner–Wadsworth–Emmons reaction of aldehydes with tet-
raethyl methylenebisphosphonate,3 palladium-catalyzed
reaction of 1-alkenyl bromides with diethyl phosphite,4
dehydration of b-hydroxyphosphonates5 and Peterson re-
action of aldehydes with diethyl trimethylsilylmeth-
ylphosphonate.6 Other, equally attractive methods involve
Heck coupling of aryl bromides, aryldiazonium salts or
arylboronic acids with diethyl vinylphosphonate,7 cross
metathesis of diethyl vinylphosphonate with terminal ole-
fins,8 reduction of the corresponding 1-alkynyl-
phosphonates9 and finally palladium-catalyzed reaction of
E- and Z-alkenylboronic acids with triethylphosphite.10
Although these protocols have found widespread utility
In order to achieve high conversion of the acid 1 in a short
period of time 1.3 equivalents of aldehyde were routinely
used. The amounts of b-alanine and AcOH were held con-
stant. The progress of each reaction was monitored by 1H
and 31P NMR spectroscopy. The reactions with several al-
dehydes 2a–k were terminated within 20 to 22 hours pro-
viding the alkenoic acids 3a–k, each as a mixture of E and
Z isomers with close to a 6:1 ratio. Data collected in
Table 1 show that catalytic system proved to be versatile
with respect not only to the condensation of a-substituted
aldehydes 2j,k but also aromatic aldehydes 2a–i contain-
ing electron-withdrawing or electron-donating substitu-
ents on the aromatic ring. No reaction was observed with
a-unsubstituted aliphatic aldehydes, m- and p-hydroxy-
benzaldehydes or indole-3-carboxaldehyde.
The crude (E,Z)-alkenoic acids 3a–k were then converted
into the dicyclohexylammonium salts 4a–k. Convenient-
ly, the crystalline salts 4a–k were isolated as the E iso-
mers, exclusively. We believe that Z to E isomerization of
SYNTHESIS 2005, No. 17, pp 2887–2896
Advanced online publication: 29.09.2005
DOI: 10.1055/s-2005-918406; Art ID: Z08205SS
x
x.
x
x
.
2
0
0
5
© Georg Thieme Verlag Stuttgart · New York

2888
H. Krawczyk, Ł. Albrecht
O
O
O
O
a
(EtO)2P
COOH
R
b
(EtO)2P
COO NH2(c-Hex)2
R
(EtO)2P
COOH
R
H
H
H
2a–k
1
(E,Z)-3a–k
(E)-4a–k
O
O
(EtO)2P
COOH
R
(EtO)2P
H
R
c
d
H
H
(E)-3a–i
(E,Z)-3j,k
(E)-5a–i
Scheme 1 Reagents and conditions: (a) 27 mol% CH3COOH, 10 mol% b-alanine, benzene, reflux, 20–22 h.; (b) (c-Hex)2NH, benzene, r.t.;
(c) ion-exchange chromatography; (d) 40 mol% piperidine, toluene, reflux, 2 h.
the acids 3a–k is induced by thermodynamically con- of a catalytic amount of piperidine (40 mol%) for two
trolled Michael addition and readdition of dicyclohexyl- hours. Under these conditions the decarboxylation of (E)-
amine. The salts (E)-4a–i were converted into the 3-arylacrylic acids 3a–i proved to be highly efficient pro-
corresponding E-acrylic acids 3a–i by ion-exchange chro- viding the corresponding (E)-2-arylvinylphosphonates
matography in nearly quantitative yields. The ion-ex- 5a–i in fully stereoselective manner. None of the Z iso-
change chromatography of the alkenoates 4j,k was mers were detected by NMR analysis of the crude reaction
accompanied by their partial isomerization. The corre- mixture. However, this method proved to be ineffective
sponding acids 3j,k were isolated as mixtures of E and Z for decarboxylation of the alkenoic acids 3j,k. The result-
isomers in ratios 6:1 and 95:5, respectively.
ing (E)-2-arylvinylphosphonates 5a–i were purified by
column chromatography and their physical properties
were found to be identical with those given in the litera-
ture. The structures of new compounds were assigned on
the basis of the corresponding spectral data.
With the suitable substrates in hand, we turned our atten-
tion to their effective conversion into vinylphosphonates
5. Guided by the knowledge of pyridine-catalyzed decar-
boxylation of arylidenemalonic acids,14 we have devised
a method for the decarboxylation of the acrylic acids 3a– It occurred to us that the formation of the acids 3 and their
k using piperidine as a catalyst (Scheme 1, Table 1). The decarboxylation could be carried out in a single synthetic
acids 3a–k were heated in boiling toluene in the presence operation by a proper choice of the solvent and catalyst.
Table 1 Dicyclohexylammonium Acrylates 4a–k, Phosphonoacrylic Acids 3a–k and Vinylphosphonates 5a–i Prepared
Entry
R
Yield (%)
Dicyclohexylammonium acrylate 4 Acrylic acid 3
Vinylphosphonate 5
a
b
c
d
e
f
4-NO2C6H4
82
74
76
73
71
75
96
91
95
93
92
94
89
83
80
84
81
81
3-NO2C6H4
4-CH3C6H4
4-CH3OC6H4
3,4-(CH3O)2C6H3
O
O
g
4-BrC6H4
77
67
94
89
82
86
h
O
i
70
91
77
O
H3C
j
(CH3)2CH
cC6H11
69
71
95
94
–
–
k
Synthesis 2005, No. 17, 2887–2896 © Thieme Stuttgart · New York

PAPER
Knoevenagel Reaction of Diethylphosphonoacetic Acid
2889
O
To validate this hypothesis piperidine–AcOH was exam-
ined as the catalyst of the selected condensations. The re-
action of aldehydes 2a–k with the acid 1 performed in
boiling benzene in the presence of a catalytic amount of
piperidine (27 mol%) and AcOH (20 mol%) failed to give
any products. However, changing the solvent to toluene
brought some interesting results.
O
(EtO)2P
(EtO)2P
H
O
a
COOH
Ar
H
H
Ar
1
(E)-7a–e
6a–e
Scheme 2 Reagents and conditions: (a) 20 mol% CH3COOH, 27
mol% piperidine, toluene, reflux, 20 h.
The reactions of the acid 1 with aliphatic aldehydes 2j,k
performed in boiling toluene were not chemoselective.
Under the same conditions aromatic aldehydes 2a–i af-
forded the corresponding vinylphosphonates 5a–i accom-
panied by small amounts of other organophosphorus
compounds and unreacted starting material. In practice,
the one-pot methodology could be effectively applied to
benzaldehydes 6a–d bearing hydroxy group on the aro-
matic ring and indole 3-carboxaldehyde (6e) (Scheme 2,
Table 2). All these reactions were terminated within 20
hours and the resulting E-vinylphosphonates 7a–e were
isolated by column chromatography.
compound was thermally unstable and underwent decom-
position to give the phosphonate 9 on heating in boiling
benzene. Our recent efforts to optimize the synthesis of
the phosphonate 9 have led to remarkable observation that
efficiency of the decarboxylation can be improved signif-
icantly by using DABCO as a catalyst (Scheme 3).
O
(EtO)2P
O
(EtO)2P
a
COONH2(c-Hex)2
9
8
In parallel investigations, we studied the condensation of
formaldehyde with the acid 1 as a route to diethyl vi-
nylphosphonate (9). In one of our previous papers we re-
ported on the synthesis of dicyclohexylammonium 2-
(diethoxyphosphoryl)acrylate (8).13 We found that this
Scheme 3 Reagents and conditions: (a) 1 equiv DABCO, benzene,
reflux.
It is likely that the above reaction involves addition of
DABCO to the acrylic acid 10 to give the zwitterionic in-
termediate 11 followed by spontaneous decarboxylative
elimination of the latter in tautomeric form of the carbox-
ylate anion 12 (Scheme 4).
Table 2 Vinylphosphonates 7a–e Prepared
Entry Aldehyde 6
Vinylphosphonate 7
Yield
(%)
Based on these results we have come to the conclusion
that the vinylphosphonate 9 can be obtained directly from
formaldehyde and the acid 1. Indeed, the reaction of the
acid 1 with excess of formaldehyde performed in boiling
benzene in the presence of catalytic amounts of dicyclo-
hexylamine (15 mol%) and DABCO (15 mol%) afforded
the phosphonate 9 in 73% yield (Scheme 5).
O
O
a
O
82
(EtO)2P
H
H
H
HO
H
OH
OH
b
68
80
O
(EtO)2P
H
H
HO
In summary, we have developed a novel and effective
method for the synthesis of diethyl vinylphosphonates
based on the Knoevenagel type reaction of aromatic alde-
hydes and formaldehyde with diethylphosphonoacetic ac-
id. Particular attention has been paid to the generality of
the process that guarantees the synthesis of a range of (E)-
2-arylvinylphosphonates in good yields and in a stereose-
lective manner.
H
c
O
O
MeO
(EtO)2P
H
OMe
OH
HO
H
NMR spectra were recorded on a Bruker DPX 250 instrument at
250.13 MHz for 1H, 62.9 MHz for 13C and 101.3 MHz for 31P NMR,
using TMS as internal and 85% H3PO4 as external standard. The
multiplicity of carbons was determined by DEPT experiments. IR
spectra were measured on a Specord M80 (Zeiss) instrument. Ele-
mental analyses were performed on a Perkin–Elmer PE 2400 ana-
lyzer. Melting points were determined in open capillaries and are
uncorrected. Diethylphosphonoacetic acid (1) was prepared accord-
ing to the literature procedure.15
d
79
76
O
O
(EtO)2P
H
HO
H
OH
OH
H
HO
e
O
O
(EtO)2P
H
H
Dicyclohexylammonium (E)-2-(Diethoxyphosphoryl)acrylates
(4); General Procedure
A mixture of diethylphosphonoacetic acid (1; 19.6 g, 0.1 mol), al-
H
N
H
NH
dehyde 2 (0.13 mol), b-alanine (0.89 g, 0.01 mol) and AcOH (1.62
Synthesis 2005, No. 17, 2887–2896 © Thieme Stuttgart · New York

2890
H. Krawczyk, Ł. Albrecht
O
O
(EtO)2P
COONH2(c-Hex)2
(EtO)2P
COOH
(c-Hex)2NH
8
10
O
OH
O
O
O
(EtO)2P
DABCO
(EtO)2P
CO2
(EtO)2P
N
– CO2
– DABCO
– (c-Hex)2NH
N
N
N
11
12
9
Scheme 4
O
O
Anal. Calcd for C25H39N2O7P: C, 58.81; H, 7.70. Found: C, 58.94;
H, 7.78.
a
(EtO)2P
COOH
(EtO)2P
Dicyclohexylammonium (E)-2-Diethoxyphosphoryl-3-
(p-tolyl)acrylate (4c)
9
1
Yield: 76%; white crystals; mp 157–159 °C.
IR (CCl4): 2984, 1628, 1392, 1264, 1028, 952, 764 cm–1.
Scheme 5 Reagents and conditions: (a) 2.2 equiv (HCHO)n, 15
mol% DABCO, 15 mol% (c-Hex)2NH, benzene, reflux.
1H NMR (250 MHz, CDCl3): d = 1.03–1.24 (m, 6 H, 3 × CH2), 1.34
(t, 3JHH = 7.1 Hz, 6 H, 2 × CH3CH2OP), 1.41–1.61 (m, 6 H, 3 × CH2),
1.70–1.74 (m, 4 H, 2 × CH2), 1.94–1.99 (m, 4 H, 2 × CH2), 2.32 (s,
3 H, CH3Ar), 2.85–2.94 (m, 2 H, 2 × CHN), 4.13–4.25 (m, 4 H, 2 ×
g, 0.027 mol) in benzene (200 mL) was heated at reflux under
Dean–Stark water separator for 20–22 h. The reaction progress was
occasionally monitored with 31P NMR. After the acid 1 was com-
pletely consumed, dicyclohexylamine was added (18.1 g, 0.1 mol)
and the solvent was evaporated. The solid residue was suspended in
Et2O and the crystals were collected by filtration to afford the crude
product. Recrystallization of the solid from CH2Cl2–acetone afford-
ed the acrylate 4.
CH3CH2OP), 7.08 (d, 3JHH = 8.1 Hz, 2 H, 2 × CHAr), 7.11 (d, 3JHP
=
26.5 Hz, 1 H, CHAr), 7.59 (d, 3JHH = 8.1 Hz, 2 H, 2 × CHAr).
31P NMR (101 MHz, CDCl3): d = 19.06.
Anal. Calcd for C26H42NO5P: C, 65.11; H, 8.83. Found: C, 65.00; H,
8.76.
Dicyclohexylammonium (E)-2-Diethoxyphosphoryl-3-(4-meth-
oxyphenyl)acrylate (4d)
Yield: 73%; white crystals; mp 160–162 °C.
IR (CCl4): 2936, 1628, 1512, 1396, 1240, 1176, 1024, 756 cm–1.
Dicyclohexylammonium (E)-2-Diethoxyphosphoryl-3-(4-nitro-
phenyl)acrylate (4a)
Yield: 82%; pale yellow crystals; mp 155–157 °C.
IR (CCl4): 2936, 1628, 1528, 1348, 1240, 1108, 1024, 968, 784
cm–1.
1H NMR (250 MHz, CDCl3): d = 0.96–1.26 (m, 6 H, 3 × CH2), 1.34
(t, 3JHH = 7.1 Hz, 6 H, 2 × CH3CH2OP), 1.41–1.61 (m, 6 H, 3 × CH2),
1.70–1.75 (m, 4 H, 2 × CH2), 1.95–2.00 (m, 4 H, 2 × CH2), 2.88–
2.97 (m, 2 H, 2 × CHN), 3.80 (s, 3 H, CH3OAr), 4.12–4.24 (m, 4 H,
1H NMR (250 MHz, CDCl3): d = 0.99–1.27 (m, 6 H, 3 × CH2), 1.37
(t, 3JHH = 7.0 Hz, 6 H, 2 × CH3CH2OP), 1.38–1.51 (m, 4 H, 2 × CH2),
1.62–1.77 (m, 6 H, 3 × CH2), 1.95–1.99 (m, 4 H, 2 × CH2), 2.88–
2.98 (m, 2 H, 2 × CHN), 4.15–4.26 (m, 4 H, 2 × CH3CH2OP), 7.15
3
2 × CH3CH2OP), 6.80 (d, JHH = 8.8 Hz, 2 H, 2 × CHAr), 7.08 (d,
3JHP = 26.5 Hz, 1 H, CHAr), 7.67 (d, 3JHH = 8.8 Hz, 2 H, 2 × CHAr).
31P NMR (101 MHz, CDCl3): d = 19.45.
3
3
(d, JHP = 25.8 Hz, 1 H, CHAr), 7.85 (d, JHH = 8.8 Hz, 2 H, 2 ×
CHAr), 8.14 (d, 3JHH = 8.8 Hz, 2 H, 2 × CHAr).
31P NMR (101 MHz, CDCl3): d = 16.79.
Anal. Calcd for C26H42NO6P: C, 63.01; H, 8.54. Found: C, 62.88; H,
8.47.
Anal. Calcd for C25H39N2O7P: C, 58.81; H, 7.70. Found: C, 58.94;
H, 7.76.
Dicyclohexylammonium (E)-2-Diethoxyphosphoryl-3-(3,4-
dimethoxyphenyl)acrylate (4e)
Yield: 71%; white crystals; mp 155–157 °C.
Dicyclohexylammonium (E)-2-Diethoxyphosphoryl-3-(3-nitro-
phenyl)acrylate (4b)
IR (CCl4): 2936, 1628, 1600, 1508, 1396, 1320, 1236, 1132, 1020,
952, 784 cm–1.
Yield: 74%; white crystals; mp 124–126 °C.
IR (CCl4): 2936, 1628, 1532, 1352, 1248, 1032, 964, 760 cm–1.
1H NMR (250 MHz, CDCl3): d = 1.03–1.24 (m, 6 H, 3 × CH2), 1.35
(t, 3JHH = 7.1 Hz, 6 H, 2 × CH3CH2OP), 1.43–1.61 (m, 6 H, 3 × CH2),
1.69–1.74 (m, 4 H, 2 × CH2), 1.94–1.98 (m, 4 H, 2 × CH2), 2.83–
2.92 (m, 2 H, 2 × CHN), 3.85 (s, 3 H, CH3OAr), 3.86 (s, 3 H,
CH3OAr), 4.13–4.24 (m, 4 H, 2 × CH3CH2OP), 6.76 (d, 3JHH = 9.0
1H NMR (250 MHz, CDCl3): d = 0.90–1.29 (m, 6 H, 3 × CH2), 1.37
(t, 3JHH = 7.0 Hz, 6 H, 2 × CH3CH2OP), 1.40–1.62 (m, 6 H, 3 × CH2),
1.71–1.76 (m, 4 H, 2 × CH2), 1.97–2.01 (m, 4 H, 2 × CH2), 2.89–
2.98 (m, 2 H, 2 × CHN), 4.16–4.26 (m, 4 H, 2 × CH3CH2OP), 7.15
(d, 3JHP = 26.0 Hz, 1 H, CHAr), 7.48 (t, 3JHH = 8.0 Hz, 1 H, CHAr),
3
Hz, 1 H, CHAr), 7.07 (d, JHP = 26.5 Hz, 1 H, CHAr), 7.30 (d,
3
3
7.95 (d, JHH = 8.0 Hz, 1 H, CHAr), 8.14 (d, JHH = 8.0 Hz, 1 H,
3JHH = 9.0 Hz, 1 H, CHAr), 7.32 (s, 1 H, CHAr).
31P NMR (101 MHz, CDCl3): d = 19.43.
CHAr), 8.66 (s, 1 H, CHAr).
31P NMR (101 MHz, CDCl3): d = 17.27.
Synthesis 2005, No. 17, 2887–2896 © Thieme Stuttgart · New York

PAPER
Knoevenagel Reaction of Diethylphosphonoacetic Acid
2891
Anal. Calcd for C27H44NO7P: C, 61.70; H, 8.44. Found: C, 61.59; H,
8.35.
Anal. Calcd for C24H40NO6P: C, 61.39; H, 8.59. Found: C, 61.29; H,
8.50.
Dicyclohexylammonium (E)-3-Benzo[1,3]dioxol-5-yl-2-(di-
ethoxyphosphoryl)acrylate (4f)
Yield: 75%; white crystals; mp 157–159 °C.
Dicyclohexylammonium (E)-2-(Diethoxyphosphoryl)-4-methyl-
2-pentenoate (4j)
Yield: 69%; white crystals; mp 106–108 °C.
IR (CCl4): 2936, 1624, 1548, 1488, 1440, 1400, 1304, 1240, 1200,
1100, 1020, 968, 784 cm–1.
IR (CCl4): 2936, 1624, 1392, 1328, 1280, 1244, 1160, 1036, 792
cm–1.
3
1H NMR (250 MHz, CDCl3): d = 1.05–1.24 (m, 6 H, 3 × CH2), 1.34
(t, 3JHH = 7.0 Hz, 6 H, 2 × CH3CH2OP), 1.42–1.60 (m, 6 H, 3 × CH2),
1.71–1.76 (m, 4 H, 2 × CH2), 1.97–2.01 (m, 4 H, 2 × CH2), 2.90–
2.99 (m, 2 H, 2 × CHN), 4.11–4.25 (m, 4 H, 2 × CH3CH2OP), 5.93
1H NMR (250 MHz, CDCl3): d = 1.05 [d, JHH = 6.5 Hz, 6 H,
(CH3)2CH], 1.13–1.30 (m, 6 H, 3 × CH2), 1.31 (t, 3JHH = 7.0 Hz, 6
H, 2 × CH3CH2OP), 1.46–1.65 (m, 6 H, 3 × CH2), 1.76–1.79 (m, 4
H, 2 × CH2), 2.01–2.06 (m, 4 H, 2 × CH2), 2.93–3.05 (m, 2 H, 2 ×
CHN), 3.02–3.16 [m, 1 H, (CH3)2CH], 4.06–4.18 (m, 4 H, 2 ×
CH3CH2OP), 6.29 (dd, 3JHP = 24.2 Hz, 3JHH = 9.5 Hz, 1 H, C=CH).
3
(s, 2 H, CH2O2Ar), 6.73 (d, JHH = 8.3 Hz, 1 H, CHAr), 7.03 (d,
3JHP = 26.3 Hz, 1 H, CHAr), 7.10 (dd, 3JHH = 8.3 Hz, 4JHH = 1.5 Hz,
1 H, CHAr), 7.42 (d, 4JHH = 1.5 Hz, 1 H, CHAr).
31P NMR (101 MHz, CDCl3): d = 18.96.
31P NMR (101 MHz, CDCl3): d = 19.22.
Anal. Calcd for C22H42NO5P: C, 61.23; H, 9.81. Found: C, 61.35; H,
9.92.
Anal. Calcd for C26H40NO7P: C, 61.28; H, 7.91. Found: C, 61.13; H,
7.84.
Dicyclohexylammonium (E)-3-Cyclohexyl-2-(diethoxyphos-
phoryl)acrylate (4k)
Yield: 71%; white crystals; mp 132–134 °C.
Dicyclohexylammonium (E)-2-Diethoxyphosphoryl-3-(4-bro-
mophenyl)acrylate (4g)
Yield: 77%; white crystals; mp 156–158 °C.
IR (CCl4): 2936, 1624, 1448, 1396, 1316, 1244, 1164, 1032, 960,
776 cm–1.
IR (CCl4): 2936, 1624, 1520, 1464, 1384, 1312, 1248, 1100, 1028,
784 cm–1.
1H NMR (250 MHz, CDCl3): d = 1.06–1.22 (m, 11 H, CH2), 1.31
(dt, 3JHH = 7.3 Hz, 4JHP = 0.5 Hz, 6 H, 2 × CH3CH2OP), 1.47–1.81
(m, 15 H, CH2), 2.02–2.06 (m, 4 H, CH2), 2.81–2.84 [m, 1 H,
(CH2)5CH], 2.92–3.02 (m, 2 H, 2 × CHN), 4.06–4.17 (m, 4 H, 2 ×
CH3CH2OP), 6.32 (dd, 3JHP = 24.5 Hz, 3JHH = 9.5 Hz, 1 H, C=CH).
1H NMR (250 MHz, CDCl3): d = 1.01–1.27 (m, 6 H, 3 × CH2), 1.35
(t, 3JHH = 7.0 Hz, 6 H, 2 × CH3CH2OP), 1.43–1.65 (m, 6 H, 3 × CH2),
1.73–1.78 (m, 4 H, 2 × CH2), 1.95–2.00 (m, 4 H, 2 × CH2), 2.87–
2.97 (m, 2 H, 2 × CHN), 4.09–4.25 (m, 4 H, 2 × CH3CH2OP), 7.07
3
3
(d, JHP = 26.0 Hz, 1 H, CHAr), 7.40 (d, JHH = 8.5 Hz, 2 H, 2 ×
31P NMR (101 MHz, CDCl3): d = 19.38.
CHAr), 7.56 (d, 3JHH = 8.5 Hz, 2 H, 2 × CHAr).
Anal. Calcd for C25H46NO5P: C, 63.67; H, 9.83. Found: C, 63.75; H,
9.91.
31P NMR (101 MHz, CDCl3): d = 17.95.
Anal. Calcd for C25H39BrNO5P: C, 55.15; H, 7.22. Found: C, 55.29;
H, 7.31.
2-(Diethoxyphosphoryl)acrylic Acids (3); General Procedure
Ion-exchange chromatography of the salts 4a–k (0.05 mol) was per-
formed on a glass column packed with Dowex 50W using H2O–ac-
etone (1:1) as eluent. The eluent was evaporated to give an oily
residue. The residue was dissolved in acetone and after evaporation
of the solvent it was left to crystallize. The solid was suspended in
Et2O, collected by filtration and air-dried.
Dicyclohexylammonium (E)-2-(Diethoxyphosphoryl)-3-(furan-
2-yl)acrylate (4h)
Yield: 67%; pale yellow crystals; mp 141–143 °C.
IR (CCl4): 2936, 1628, 1556, 1384, 1296, 1236, 1160, 1020, 784
cm–1.
1H NMR (250 MHz, CDCl3): d = 1.07–1.24 (m, 6 H, 3 × CH2), 1.34
(t, 3JHH = 7.1 Hz, 6 H, 2 × CH3CH2OP), 1.46–1.62 (m, 6 H, 3 × CH2),
1.72–1.77 (m, 4 H, 2 × CH2), 2.03–2.07 (m, 4 H, 2 × CH2), 2.95–
3.04 (m, 2 H, 2 × CHN), 4.12–4.23 (m, 4 H, 2 × CH3CH2OP), 6.40
(dd, 3JHH = 3.4 Hz, 3JHH = 1.8 Hz, 1 H, CHAr), 6.89 (d, 3JHH = 3.4 Hz,
1 H, CHAr), 6.99 (d, 3JHP = 25.8 Hz, 1 H, CHAr), 7.38 (d, 3JHH = 1.8
Hz, 1 H, CHAr).
(E)-2-Diethoxyphosphoryl-3-(4-nitrophenyl)acrylic Acid (3a)
Yield: 96%; pale yellow crystals; mp 147–149 °C.
IR (CCl4): 2864, 1708, 1592, 1520, 1376, 1192, 1032, 760 cm–1.
1H NMR (250 MHz, acetone-d6): d = 1.34 (dt, 3JHH = 7.3 Hz, 4JHP
0.5 Hz, 6 H, 2 × CH3CH2OP), 4.12–4.24 (m, 4 H, 2 × CH3CH2OP),
7.65 (d, 3JHP = 24.0 Hz, 1 H, CHAr), 7.85 (d, 3JHH = 8.8 Hz, 2 H,
2 × CHAr), 8.30 (d, 3JHH = 8.8 Hz, 2 H, 2 × CHAr).
=
31P NMR (101 MHz, CDCl3): d = 18.61.
13C NMR (62.9 MHz, acetone-d6): d = 16.38 (d, 3JCP = 6.2 Hz, 2 ×
CH3CH2OP), 63.66 (d, 2JCP = 5.0 Hz, 2 × CH3CH2OP), 124.38 (2 ×
CHAr), 130.82 (2 × CHAr), 130.82 (d, 1JCP = 175.0 Hz, PC), 141.12
Anal. Calcd for C23H38NO6P: C, 60.64; H, 8.41. Found: C, 60.51; H,
8.34.
3
2
(d, JCP = 21.0 Hz, CAr), 144.21 (d, JCP = 6.1 Hz, CHAr), 149.06
Dicyclohexylammonium (E)-2-(Diethoxyphosphoryl)-3-(5-
methylfuran-2-yl)acrylate (4i)
Yield: 70%; yellow crystals; mp 141–143 °C.
(CAr), 167.16 (d, 2JCP = 11.5 Hz, COOH).
31P NMR (101 MHz, acetone-d6): d = 12.19.
IR (CCl4): 2936, 1624, 1392, 1248, 1032, 964, 800 cm–1.
Anal. Calcd for C13H16NO7P: C, 47.42; H, 4.90. Found: C, 47.24;
H, 4.77.
1H NMR (250 MHz, CDCl3): d = 1.05–1.23 (m, 6 H, 3 × CH2), 1.33
(t, 3JHH = 7.0 Hz, 6 H, 2 × CH3CH2OP), 1.45–1.61 (m, 6 H, 3 × CH2),
1.71–1.76 (m, 4 H, 2 × CH2), 2.01–2.06 (m, 4 H, 2 × CH2), 2.28 (s,
3 H, CH3Ar), 2.94–3.03 (m, 2 H, 2 × CHN), 4.11–4.22 (m, 4 H, 2 ×
CH3CH2OP), 6.00 (d, 3JHH = 2.8 Hz, 1 H, CHAr), 6.86 (d, 3JHH = 2.8
Hz, 1 H, CHAr), 6.96 (d, 3JHP = 25.8 Hz, 1 H, CHAr).
(E)-2-Diethoxyphosphoryl-3-(3-nitrophenyl)acrylic Acid (3b)
Yield: 91%; white crystals; mp 118–120 °C.
IR (CCl4): 2984, 2528, 1708, 1624, 1528, 1352, 1200, 1012, 784
cm–1.
3
31P NMR (101 MHz, CDCl3): d = 19.26.
1H NMR (250 MHz, acetone-d6): d = 1.34 (t, JHH = 7.0 Hz, 6 H,
2 × CH3CH2OP), 4.12–4.24 (m, 4 H, 2 × CH3CH2OP), 7.65 (d,
Synthesis 2005, No. 17, 2887–2896 © Thieme Stuttgart · New York

2892
H. Krawczyk, Ł. Albrecht
3JHP = 24.0 Hz, 1 H, CHAr), 7.77 (t, 3JHH = 8.0 Hz, 1 H, CHAr), 8.02
5.1 Hz, 2 × CH3CH2OP), 112.22 (CHAr), 113.35 (CHAr), 123.14 (d,
3
3
(d, 3JHH = 8.0 Hz, 1 H, CHAr), 8.30 (d, JHH = 8.0 Hz, 1 H, CHAr),
1JCP = 181.6 Hz, PC), 124.58 (CHAr), 127.26 (d, JCP = 21.1 Hz,
8.50 (s, 1 H, CHAr).
CAr), 146.91 (d, 2JCP = 6.4 Hz, CHAr), 150.04 (CAr), 150.44 (CAr),
168.25 (d, 2JCP = 12.4 Hz, COOH).
31P NMR (101 MHz, acetone-d6): d = 14.82.
13C NMR (62.9 MHz, acetone-d6): d = 16.47 (d, 3JCP = 6.4 Hz, 2 ×
2
CH3CH2OP), 63.77 (d, JCP = 5.2 Hz, 2 × CH3CH2OP), 124.21
1
(CHAr), 125.25 (CHAr), 129.56 (d, JCP = 174.9 Hz, PC), 130.95
Anal. Calcd for C15H21O7P: C, 52.33; H, 6.15. Found: C, 52.18; H,
6.08.
(CHAr), 136.00 (CHAr), 136.50 (d, 3JCP = 21.4 Hz, CAr), 144.73 (d,
2
2JCP = 6.5 Hz, CHAr), 149.18 (CAr), 167.18 (d, JCP = 11.8 Hz,
COOH).
(E)-3-Benzo[1,3]dioxol-5-yl-2-(diethoxyphosphoryl)acrylic
Acid (3f)
Yield: 94%; white crystals; mp 149–151 °C.
31P NMR (101 MHz, acetone-d6): d = 12.30.
Anal. Calcd for C13H16NO7P: C, 47.42; H, 4.90. Found: C, 47.28; H,
4.78.
IR (CCl4): 2920, 1712, 1600, 1488, 1448, 1260, 1192, 1016, 784
cm–1.
(E)-2-Diethoxyphosphoryl-3-(p-tolyl)acrylic Acid (3c)
Yield: 95%; white crystals; mp 96–98 °C.
1H NMR (250 MHz, acetone-d6): d = 1.31 (dt, 3JHH = 7.0 Hz, 4JHP
=
0.5 Hz, 6 H, 2 × CH3CH2OP), 4.06–4.18 (m, 4 H, 2 × CH3CH2OP),
6.08 (s, 2 H, CH2O2Ar), 6.92 (d, 3JHH = 8.0 Hz, 1 H, CHAr), 7.16 (d,
3JHH = 8.0 Hz, 1 H, CHAr), 7.18 (s, 1 H, CHAr), 7.39 (d, 3JHP = 24.5
Hz, 1 H, CHAr).
IR (CCl4): 2912, 1708, 1608, 1512, 1400, 1300, 1288, 1184, 1040,
964, 792 cm–1.
1H NMR (250 MHz, acetone-d6): d = 1.32 (dt, 3JHH = 7.3 Hz, 4JHP
=
0.3 Hz, 6 H, 2 × CH3CH2OP), 2.36 (s, 3 H, CH3Ar), 4.08–4.19 (m,
13C NMR (62.9 MHz, acetone-d6): d = 16.49 (d, 3JCP = 6.5 Hz, 2 ×
4 H, 2 × CH3CH2OP), 7.25 (d, 3JHH = 8.0 Hz, 2 H, 2 × CHAr), 7.47
CH3CH2OP), 62.99 (d, JCP = 5.0 Hz, 2 × CH3CH2OP), 102.79
2
3
3
(d, JHP = 24.5 Hz, 1 H, CHAr), 7.51 (d, JHH = 8.0 Hz, 2 H, 2 ×
(CH2O2Ar), 108.92 (CHAr), 109.19 (CHAr), 124.25 (d, 1JCP = 177.0
Hz, PC), 126.61 (CHAr), 128.88 (d, 3JCP = 21.1 Hz, CAr), 146.19 (d,
CHAr).
2JCP = 6.3 Hz, CHAr), 149.10 (CAr), 150.57 (CAr), 168.04 (d, 2JCP
=
13C NMR (62.9 MHz, acetone-d6): d = 16.47 (d, 3JCP = 6.5 Hz, 2 ×
12.1 Hz, COOH).
31P NMR (101 MHz, acetone-d6): d = 14.30.
2
CH3CH2OP), 31.34 (CH3Ar), 63.38 (d, JCP = 5.1 Hz, 2 ×
1
CH3CH2OP), 124.93 (d, JCP = 178.3 Hz, PC), 130.18 (2 × CHAr),
3
130.25 (2 × CHAr), 131.94 (d, JCP = 20.8 Hz, CAr), 141.67 (CAr),
Anal. Calcd for C14H17O7P: C, 51.23; H, 5.22. Found: C, 51.03; H,
5.14.
147.03 (d, 2JCP = 6.2 Hz, CHAr), 167.91 (d, 2JCP = 12.5 Hz, COOH).
31P NMR (101 MHz, acetone-d6): d = 14.13.
(E)-2-Diethoxyphosphoryl-3-(4-bromophenyl)acrylic Acid (3g)
Yield: 94%; white crystals; mp 106–108 °C.
IR (CCl4): 2912, 1712, 1528, 1484, 1396, 1204, 1032, 760 cm–1.
Anal. Calcd for C14H19O5P: C, 56.37; H, 6.42. Found: C, 56.27; H,
6.35.
(E)-2-Diethoxyphosphoryl-3-(4-methoxyphenyl)acrylic Acid
(3d)
Yield: 93%; white crystals; mp 95–97 °C.
IR (CCl4): 2912, 1708, 1608, 1512, 1308, 1192, 1012, 788 cm–1.
1H NMR (250 MHz, acetone-d6): d = 1.32 (dt, 3JHH = 7.0 Hz, 4JHP
=
0.5 Hz, 6 H, 2 × CH3CH2OP), 4.09–4.21 (m, 4 H, 2 × CH3CH2OP),
7.50 (d, 3JHP = 24.0 Hz, 1 H, CHAr), 7.54–7.66 (m, 4 H, 4 × CHAr).
13C NMR (62.9 MHz, acetone-d6): d = 16.47 (d, 3JCP = 6.5 Hz, 2 ×
3
2
1H NMR (250 MHz, acetone-d6): d = 1.31 (t, JHH = 7.0 Hz, 6 H,
CH3CH2OP), 63.50 (d, JCP = 5.2 Hz, 2 × CH3CH2OP), 124.93
2 × CH3CH2OP), 3.85 (s, 3 H, CH3OAr), 4.07–4.18 (m, 4 H, 2 ×
(CAr), 127.34 (d, 1JCP = 177.06 Hz, PC), 131.81 (2 × CHAr), 132.66
(2 × CHAr), 133.96 (d, 3JCP = 21.0 Hz, CAr), 145.74 (d, 2JCP = 6.5 Hz,
CHAr), 167.45 (d, 2JCP = 12.1 Hz, COOH).
CH3CH2OP), 6.99 (d, 3JHH = 8.8 Hz, 2 H, 2 × CHAr), 7.45 (d, 3JHP
24.6 Hz, 1 H, CHAr), 7.61 (d, 3JHH = 8.8 Hz, 2 H, 2 × CHAr).
=
13C NMR (62.9 MHz, acetone-d6): d = 16.44 (d, 3JCP = 6.7 Hz, 2 ×
31P NMR (101 MHz, acetone-d6): d = 14.73.
2
CH3CH2OP), 55.72 (CH3OAr), 63.25 (d, JCP = 5.2 Hz, 2 ×
Anal. Calcd for C13H16BrO5P: C, 43.00; H, 4.44. Found: C, 42.87;
H, 4.32.
CH3CH2OP), 114.90 (2 × CHAr), 122.63 (d, 1JCP = 179.83 Hz, PC),
3
127.01 (d, JCP = 21.2 Hz, CAr), 132.32 (2 × CHAr), 147.00 (d,
2
2JCP = 6.5 Hz, CHAr), 162.43 (CAr), 168.08 (d, JCP = 12.6 Hz,
(E)-2-(Diethoxyphosphoryl)-3-(furan-2-yl)acrylic Acid (3h)
Yield: 89%; pale yellow crystals; mp 85–87 °C.
COOH).
31P NMR (101 MHz, acetone-d6): d = 14.73.
IR (CCl4): 2864, 2552, 1716, 1620, 1544, 1472, 1392, 1188, 1016,
792 cm–1.
Anal. Calcd for C14H19O6P: C, 53.50; H, 6.09. Found: C, 53.38; H,
6.01.
1H NMR (250 MHz, acetone-d6): d = 1.32 (dt, 3JHH = 7.1 Hz, 4JHP
0.6 Hz, 6 H, 2 × CH3CH2OP), 4.08–4.19 (m, 4 H, 2 × CH3CH2OP),
=
(E)-2-Diethoxyphosphoryl-3-(3,4-dimethoxyphenyl)acrylic
Acid (3e)
Yield: 92%; white crystals; mp 126–128 °C.
IR (CCl4): 2936, 1708, 1596, 1516, 1276, 1024, 976, 784 cm–1.
6.63 (dd, 3JHH = 3.5 Hz, 3JHH = 1.8 Hz, 1 H, CHAr), 7.10 (d, 3JHH
=
3.5 Hz, 1 H, CHAr), 7.34 (d, 3JHP = 24.0 Hz, 1 H, CHAr), 7.75 (d,
3JHH = 1.8 Hz, 1 H, CHAr).
13C NMR (62.9 MHz, acetone-d6): d = 16.38 (d, 3JCP = 6.6 Hz, 2 ×
1H NMR (250 MHz, acetone-d6): d = 1.31 (dt, 3JHH = 7.3 Hz, 4JHP
=
CH3CH2OP), 63.47 (d, JCP = 5.2 Hz, 2 × CH3CH2OP), 113.45
2
0.5 Hz, 6 H, 2 × CH3CH2OP), 3.81 (s, 3 H, CH3OAr), 3.86 (s, 3 H,
CH3OAr), 4.07–4.19 (m, 4 H, 2 × CH3CH2OP), 6.99 (d, 3JHH = 8.3
Hz, 1 H, CHAr), 7.23 (dd, 3JHH = 8.3 Hz, 4JHH = 2.2 Hz, 1 H, CHAr),
(CHAr), 118.57 (CHAr), 120.28 (d, 1JCP = 182.4 Hz, PC), 133.72 (d,
2JCP = 8.0 Hz, CHAr), 147.05 (CHAr), 150.28 (d, JCP = 24.3 Hz,
3
CAr), 166.93 (d, 2JCP = 11.8 Hz, COOH).
31P NMR (101 MHz, acetone-d6): d = 14.67.
4
3
7.29 (d, JHH = 2.2 Hz, 1 H, CHAr), 7.43 (d, JHP = 24.5 Hz, 1 H,
CHAr).
Anal. Calcd for C11H15O6P: C, 48.18; H, 5.51. Found: C, 48.01; H,
5.39.
13C NMR (62.9 MHz, acetone-d6): d = 16.46 (d, 3JCP = 6.5 Hz, 2 ×
2
CH3CH2OP), 55.99 (CH3OAr), 56.03 (CH3OAr), 63.13 (d, JCP
=
Synthesis 2005, No. 17, 2887–2896 © Thieme Stuttgart · New York

PAPER
Knoevenagel Reaction of Diethylphosphonoacetic Acid
2893
(E)-2-(Diethoxyphosphoryl)-3-(5-methylfuran-2-yl)acrylic
Acid (3i)
Anal. Calcd for C13H23O5P: C, 53.79; H, 7.99. Found: C, 53.65; H,
7.88.
Yield: 91%; yellow crystals; mp 154–156 °C.
Diethyl (E)-2-Arylvinylphosphonates (5); General Procedure
A mixture of 2-(diethoxyphosphoryl)acrylic acid 3 (1 mmol) and pi-
peridine (34 mg, 0.4 mmol) in toluene (20 mL) was heated at reflux
for 2 h. The solvent was evaporated and the residue was dissolved
in CH2Cl2 (15 mL), washed with sat. aq NaHCO3 solution (10 mL)
and H2O (10 mL) and dried over MgSO4. Evaporation of the solvent
under reduced pressure afforded the crude product which was puri-
fied by column chromatography [silica gel; CH2Cl2–MeOH (98:2)
as eluent] to give pure vinylphosphonate 5.
IR (CCl4): 2904, 2544, 1712, 1624, 1588, 1512, 1368, 1348, 1188,
1092, 760 cm–1.
3
1H NMR (250 MHz, acetone-d6): d = 1.31 (t, JHH = 7.0 Hz, 6 H,
2 × CH3CH2OP), 2.33 (s, 3 H, CH3Ar), 4.06–4.17 (m, 4 H, 2 ×
CH3CH2OP), 6.26 (d, 3JHH = 3.2 Hz, 1 H, CHAr), 7.06 (d, 3JHH = 3.2
Hz, 1 H, CHAr), 7.27 (d, 3JHP = 23.8 Hz, 1 H, CHAr).
13C NMR (62.9 MHz, acetone-d6): d = 13.71 (CH3Ar), 16.50 (d,
2
3JCP = 6.5 Hz, 2 × CH3CH2OP), 62.95 (d, JCP = 5.0 Hz, 2 ×
1
CH3CH2OP), 110.22 (CHAr), 118.80 (d, JCP = 184.7 Hz, PC),
Diethyl (E)-2-(4-Nitrophenyl)vinylphosphonate (5a)7a
Yield: 89%; pale yellow crystals; mp 101–103 °C (Lit. 102–103.5
°C).
3
120.29 (CHAr), 134.01 (d, 2JCP = 8.0 Hz, CHAr), 149.26 (d, JCP
=
23.9 Hz, CAr), 157.50 (CAr), 167.17 (d, 2JCP = 11.8 Hz, COOH).
31P NMR (101 MHz, acetone-d6): d = 15.47.
IR (CCl4): 2992, 1720, 1612, 1448, 1392, 1200, 1028, 972, 804
cm–1.
Anal. Calcd for C12H17O6P: C, 50.00; H, 5.94. Found: C, 49.88; H,
5.85.
3
1H NMR (250 MHz, CDCl3): d = 1.38 (t, JHH = 7.0 Hz, 6 H, 2 ×
CH3CH2OP), 4.12–4.24 (m, 4 H, 2 × CH3CH2OP), 6.45 (dd, 3JHH
=
(E,Z)-2-(Diethoxyphosphoryl)-4-methyl-2-pentenoic Acid (3j)
Yield: 95%; colorless oil.
IR (CCl4): 2776, 1712, 1624, 1392, 1208, 1032, 812, 732 cm–1.
2
3
17.5 Hz, JHP = 16.2 Hz, 1 H, CHP), 7.54 (dd, JHP = 22.2 Hz,
3JHH = 17.5 Hz, 1 H, CHAr), 7.67 (d, 3JHH = 8.9 Hz, 2 H, 2 × CHAr),
8.26 (d, 3JHH = 8.9 Hz, 2 H, 2 × CHAr).
3
1H NMR (250 MHz, acetone-d6): d = 1.07 [d, JHH = 6.8 Hz, 6 H,
3
13C NMR (62.9 MHz, CDCl3): d = 16.06 (d, JCP = 6.3 Hz, 2 ×
(CH3)2CH, E isomer], 1.08 [d, 3JHH = 6.5 Hz, 6 H, (CH3)2CH, Z iso-
mer], 1.29 (dt, 3JHH = 7.0 Hz, 4JHP = 0.5 Hz, 6 H, 2 × CH3CH2OP),
3.03–3.25 [m, 1 H, (CH3)2CH, E isomer], 3.30–3.45 [m, 1 H,
(CH3)2CH, Z isomer], 4.04–4.15 (m, 4 H, 2 × CH3CH2OP), 6.77 (dd,
CH3CH2OP), 61.83 (d, 2JCP = 5.7 Hz, 2 × CH3CH2OP), 119.21 (d,
1JCP = 190.0 Hz, PCH), 123.76 (2 × CHAr), 128.06 (2 × CHAr),
3
2
140.55 (d, JCP = 23.5 Hz, CAr), 145.13 (d, JCP = 6.6 Hz, CHAr),
148.10 (CAr).
31P NMR (101 MHz, CDCl3): d = 17.52.
3
3JHP = 23.0 Hz, JHH = 10.0 Hz, 1 H, C=CH, E isomer), 7.44 (dd,
3JHP = 41.8 Hz, 3JHH = 11.8 Hz, 1 H, C=CH, Z isomer).
13C NMR (62.9 MHz, CDCl3): d = 15.68 (d, JCP = 6.4 Hz, 2 ×
3
Diethyl (E)-2-(3-Nitrophenyl)vinylphosphonate (5b)
Yield: 83%; pale yellow crystals; mp 44–46 °C.
IR (CCl4): 2984, 1624, 1532, 1352, 1236, 1028, 816, 736 cm–1.
CH3CH2OP, E isomer), 15.70 (d, 3JCP = 6.3 Hz, 2 × CH3CH2OP, Z
4
isomer), 21.11 (d, JCP = 1.5 Hz, 2 × CH3, Z isomer), 21.25 (d,
3
4JCP = 1.1 Hz, 2 × CH3, E isomer), 29.21 [d, JCP = 5.0 Hz,
3
3
1H NMR (250 MHz, CDCl3): d = 1.38 (t, JHH = 7.0 Hz, 6 H, 2 ×
(CH3)2CH, Z isomer], 29.59 [d, JCP = 16.3 Hz, (CH3)2CH, E iso-
mer], 62.50 (d, 2JCP = 5.6 Hz, 2 × CH3CH2OP, E isomer), 62.59 (d,
CH3CH2OP), 4.11–4.27 (m, 4 H, 2 × CH3CH2OP), 6.43 (dd, 3JHH
=
1
2JCP = 5.8 Hz, 2 × CH3CH2OP, Z isomer), 119.38 (d, JCP = 184.7
2
3
17.8 Hz, JHP = 16.3 Hz, 1 H, CHP), 7.54 (dd, JHP = 21.5 Hz,
3JHH = 17.8 Hz, 1 H, CHAr), 7.59 (t, 3JHH = 8.2 Hz, 1 H, CHAr), 7.89
(d, 3JHH = 8.2 Hz, 1 H, CHAr), 8.23 (d, 3JHH = 8.2 Hz, 1 H, CHAr),
8.37 (s, 1 H, CHAr).
1
Hz, PC, Z isomer), 121.77 (d, JCP = 183.6 Hz, PC, E isomer),
2
165.63 (d, 2JCP = 4.0 Hz, C=CH, E isomer), 165.81 (d, JCP = 18.9
Hz, COOH, Z isomer), 166.09 (d, 2JCP = 14.4 Hz, COOH, E isomer),
170.83 (d, 2JCP = 7.9 Hz, C=CH, Z isomer).
3
13C NMR (62.9 MHz, CDCl3): d = 16.03 (d, JCP = 6.3 Hz, 2 ×
31P NMR (101 MHz, acetone-d6): d = 15.09, 16.27 for E and Z iso-
mers, respectively (E:Z = 6:1).
CH3CH2OP), 61.74 (d, 2JCP = 5.6 Hz, 2 × CH3CH2OP), 117.81 (d,
1JCP = 190.2 Hz, PCH), 121.59 (CHAr), 124.06 (CHAr), 129.66
(CHAr), 133.13 (CHAr), 136.25 (d, 3JCP = 24.0 Hz, CAr), 145.15 (d,
2JCP = 6.9 Hz, CHAr), 148.26 (CAr).
Anal. Calcd for C10H19O5P: C, 48.00; H, 7.65. Found: C, 47.89; H,
7.57.
31P NMR (101 MHz, CDCl3): d = 17.75.
(E,Z)-3-Cyclohexyl-2-(diethoxyphosphoryl)acrylic Acid (3k)
Yield: 94%; white crystals; mp 64–66 °C.
Anal. Calcd for C12H16NO5P: C, 50.63; H, 5.65. Found: C, 50.88; H,
5.73.
IR (CCl4): 2928, 1720, 1612, 1448, 1392, 1200, 1028, 972, 804
cm–1.
Diethyl (E)-2-(p-Tolyl)vinylphosphonate (5c)7a
1H NMR (250 MHz, acetone-d6): d = 1.19–1.35 (m, 5 H, CH2), 1.29
(dt, 3JHH = 7.0 Hz, 4JHP = 0.5 Hz, 6 H, 2 × CH3CH2OP), 1.71–1.76
(m, 5 H, CH2), 2.89–3.00 [m, 1 H, (CH2)5CH, E isomer], 2.99–3.17
[m, 1 H, (CH2)5CH, Z isomer], 4.04–4.15 (m, 4 H, 2 × CH3CH2OP),
Yield: 80%; yellow oil.
IR (CCl4): 2984, 1616, 1512, 1248, 1028, 964, 840, 800 cm–1.
1H NMR (250 MHz, CDCl3): d = 1.35 (t, JHH = 7.0 Hz, 6 H, 2 ×
CH3CH2OP), 2.37 (s, 3 H, CH3Ar), 4.08–4.17 (m, 4 H, 2 ×
CH3CH2OP), 6.19 (dd, 3JHH = 17.5 Hz, 2JHP = 17.5 Hz, 1 H, CHP),
7.18 (d, 3JHH = 8.0 Hz, 2 H, 2 × CHAr), 7.39 (d, 3JHH = 8.0 Hz, 2 H,
2 × CHAr), 7.48 (dd, 3JHP = 22.5 Hz, 3JHH = 17.5 Hz, 1 H, CHAr).
3
3
3
6.70 (dd, JHP = 23.5 Hz, JHH = 10.0 Hz, C=CH, 1 H, E isomer),
7.35 (dd, 3JHP = 43.8 Hz, 3JHH = 11.2 Hz, 1 H, C=CH, Z isomer).
13C NMR (62.9 MHz, acetone-d6, E isomer): d = 16.07 (d, 3JCP = 6.4
Hz, 2 × CH3CH2OP), 25.04 (2 × CH2), 25.55 (CH2), 31.50 (2 ×
CH2), 39.57 [d, 3JCP = 15.7 Hz, (CH2)5CH], 62.84 (d, 2JCP = 5.6 Hz,
2 × CH3CH2OP), 122.13 (d, 1JCP = 183.29 Hz, PC), 165.07 (C=CH),
166.77 (d, 2JCP = 16.2 Hz, COOH).
31P NMR (101 MHz, acetone-d6): d = 15.98, 16.54 for E and Z iso-
mers, respectively (E:Z = 95:5).
13C NMR (62.9 MHz, CDCl3): d = 15.97 (d, JCP = 6.4 Hz, 2 ×
3
2
CH3CH2OP), 20.93 (CH3Ar), 61.27 (d, JCP = 5.4 Hz, 2 ×
CH3CH2OP), 112.24 (d, 1JCP = 191.8 Hz, PCH), 127.24 (2 × CHAr),
3
129.13 (2 × CHAr), 131.73 (d, JCP = 23.6 Hz, CAr), 140.11 (CAr),
148.25 (d, 2JCP = 6.7 Hz, CHAr).
31P NMR (101 MHz, CDCl3): d = 20.34.
Synthesis 2005, No. 17, 2887–2896 © Thieme Stuttgart · New York

2894
H. Krawczyk, Ł. Albrecht
3
Diethyl (E)-2-(4-Methoxyphenyl)vinylphosphonate (5d)7b
Yield: 84%; yellow oil.
13C NMR (62.9 MHz, CDCl3): d = 16.11 (d, JCP = 6.5 Hz, 2 ×
CH3CH2OP), 61.58 (d, 2JCP = 5.5 Hz, 2 × CH3CH2OP), 114.72 (d,
1JCP = 191.2 Hz, PCH), 124.10 (CAr), 128.80 (2 × CHAr), 131.74
(2 × CHAr), 133.46 (d, 3JCP = 23.7 Hz, CAr), 146.86 (d, 2JCP = 6.8 Hz,
CHAr).
IR (CCl4): 2984, 1604, 1512, 1304, 1260, 1176, 1024, 964, 864, 848
cm–1.
3
1H NMR (250 MHz, CDCl3): d = 1.35 (t, JHH = 7.3 Hz, 6 H, 2 ×
31P NMR (101 MHz, CDCl3): d = 19.22.
CH3CH2OP), 3.84 (s, 3 H, CH3OAr), 4.03–4.18 (m, 4 H, 2 ×
CH3CH2OP), 6.09 (dd, 3JHH = 17.8 Hz, 2JHP = 17.8 Hz, 1 H, CHP),
6.90 (d, 3JHH = 8.8 Hz, 2 H, 2 × CHAr), 7.45 (d, 3JHH = 8.8 Hz, 2 H,
2 × CHAr), 7.45 (dd, 3JHP = 23.5 Hz, 3JHH = 17.8 Hz, 1 H, CHAr).
Diethyl (E)-2-(Furan-2-yl)vinylphosphonate (5h)2d,n
Yield: 86%; red oil.
IR (CCl4): 2984, 1624, 1552, 1476, 1392, 1248, 1048, 960, 848,
812, 768 cm–1.
3
13C NMR (62.9 MHz, CDCl3): d = 15.83 (d, JCP = 6.4 Hz, 2 ×
2
CH3CH2OP), 54.71 (CH3OAr), 61.07 (d, JCP = 5.4 Hz, 2 ×
CH3CH2OP), 110.40 (d, 1JCP = 192.7 Hz, PCH), 113.68 (2 × CHAr),
1H NMR (250 MHz, CDCl3): d = 1.35 (t, JHH = 7.2 Hz, 6 H, 2 ×
3
3
127.03 (d, JCP = 23.7 Hz, CAr), 128.73 (2 × CHAr), 147.75 (d,
CH3CH2OP), 4.06–4.17 (m, 4 H, 2 × CH3CH2OP), 6.11 (dd, 3JHH
=
=
2JCP = 6.9 Hz, CHAr), 160.79 (CAr).
17.8 Hz, 2JHP = 17.8 Hz, 1 H, CHP), 6.45 (dd, 3JHH = 3.0 Hz, 3JHH
3
1.5 Hz, 1 H, CHAr), 6.55 (d, JHH = 3.0 Hz, 1 H, CHAr), 7.26 (dd,
3JHP = 22.5 Hz, 3JHH = 17.8 Hz, 1 H, CHAr), 7.46 (d, 3JHH = 1.5 Hz,
1 H, CHAr).
31P NMR (101 MHz, CDCl3): d = 20.76.
Diethyl (E)-2-(3,4-Dimethoxyphenyl)vinylphosphonate (5e)
Yield: 81%; yellow oil.
3
13C NMR (62.9 MHz, CDCl3): d = 15.90 (d, JCP = 6.4 Hz, 2 ×
CH3CH2OP), 61.35 (d, 2JCP = 5.5 Hz, 2 × CH3CH2OP), 110.75 (d,
1JCP = 194.0 Hz, PCH), 111.73 (CHAr), 113.54 (CHAr), 134.76 (d,
IR (CCl4): 2984, 1600, 1512, 1464, 1268, 1160, 1024, 964, 856, 804
cm–1.
2JCP = 7.6 Hz, CHAr), 144.16 (CHAr), 150.56 (d, JCP = 25.8 Hz,
2
3
1H NMR (250 MHz, CDCl3): d = 1.36 (t, JHH = 7.2 Hz, 6 H, 2 ×
CAr).
CH3CH2OP), 3.91 (s, 6 H, 2 × CH3OAr), 4.06–4.19 (m, 4 H, 2 ×
31P NMR (101 MHz, CDCl3): d = 19.93.
CH3CH2OP), 6.09 (dd, 3JHH = 17.5 Hz, 2JHP = 17.5 Hz, 1 H, CHP),
3
4
6.87 (d, JHH = 8.2 Hz, 1 H, CHAr), 7.03 (d, JHH = 2.0 Hz, 1 H,
CHAr), 7.08 (dd, 3JHH = 8.2 Hz, 4JHH = 2.0 Hz, 1 H, CHAr), 7.44 (dd,
3JHP = 22.5 Hz, 3JHH = 17.5 Hz, 1 H, CHAr).
Diethyl (E)-2-(5-Methylfuran-2-yl)vinylphosphonate (5i)2d
Yield: 77%; red oil.
IR (CCl4): 2984, 1624, 1580, 1392, 1248, 1028, 968, 848, 792 cm–1.
3
13C NMR (62.9 MHz, CDCl3): d = 16.05 (d, JCP = 6.4 Hz, 2 ×
2
3
CH3CH2OP), 55.51 (CH3OAr), 55.58 (CH3OAr), 61.35 (d, JCP
=
1H NMR (250 MHz, CDCl3): d = 1.34 (t, JHH = 7.0 Hz, 6 H, 2 ×
5.4 Hz, 2 × CH3CH2OP), 109.05 (CHAr), 110.67 (CHAr), 110.86 (d,
1JCP = 192.9 Hz, PCH), 121.76 (CHAr), 127.53 (d, 3JCP = 23.9 Hz,
CAr), 148.21 (d, 2JCP = 6.9 Hz, CHAr), 148.56 (CAr), 150.69 (CAr).
31P NMR (101 MHz, CDCl3): d = 20.59.
CH3CH2OP), 2.34 (s, 3 H, CH3Ar), 4.04–4.16 (m, 4 H, 2 ×
CH3CH2OP), 6.00 (dd, 3JHH = 17.2 Hz, 3JHP = 19.0 Hz, 1 H, CHAr),
3
3
6.05 (d, JHH = 3.2 Hz, 1 H, CHAr), 6.44 (d, JHH = 3.2 Hz, 1 H,
CHAr), 7.18 (dd, 3JHH = 17.2 Hz, 2JHP = 5.0 Hz, 1 H, CHP).
13C NMR (62.9 MHz, CDCl3): d = 13.48 (CH3Ar), 16.09 (d, 3JCP
=
Anal. Calcd for C14H21O5P: C, 56.00; H, 7.05. Found: C, 56.16; H,
7.14.
6.4 Hz, 2 × CH3CH2OP), 61.38 (d, 2JCP = 5.3 Hz, 2 × CH3CH2OP),
1
108.36 (CHAr), 108.66 (d, JCP = 194.7 Hz, PCH), 115.33 (CHAr),
2
2
133.28 (d, JCP = 7.7 Hz, CHAr), 147.70 (d, JCP = 25.7 Hz, CAr),
Diethyl (E)-2-(Benzo[1,3]dioxol-5-yl)vinylphosphonate (5f)
Yield: 81%; pale yellow oil.
IR (CCl4): 2984, 1616, 1492, 1448, 1256, 1032, 964, 800 cm–1.
154.87 (CAr).
31P NMR (101 MHz, CDCl3): d = 20.74.
3
1H NMR (250 MHz, CDCl3): d = 1.35 (t, JHH = 7.1 Hz, 6 H, 2 ×
Diethyl (E)-2-Arylvinylphosphonates (7); General Procedure
A mixture of diethylphosphonoacetic acid (1; 392 mg, 2 mmol), al-
dehyde 6 (2.4 mmol), piperidine (46 mg, 0.54 mmol) and AcOH (24
mg, 0.4 mmol) in toluene (20 mL) was heated at reflux for 20 h. The
reaction progress was occasionally monitored with 31P NMR. After
the acid 1 was completely consumed the solvent was evaporated
and the residue was taken up in CH2Cl2 (15 mL), washed with sat.
aq NaHCO3 solution (10 mL), H2O (10 mL) and dried over MgSO4.
Evaporation of the solvent under reduced pressure afforded the
crude product, which was purified by column chromatography (sil-
ica gel; CH2Cl2–MeOH, 98:2 as eluent) to give pure vinylphospho-
nate 7.
CH3CH2OP), 4.05–4.19 (m, 4 H, 2 × CH3CH2OP), 6.01 (s, 2 H,
3
2
CH2O2Ar), 6.05 (dd, JHH = 17.4 Hz, JHP = 17.4 Hz, 1 H, CHP),
6.81 (d, 3JHH = 7.9 Hz, 1 H, CHAr), 6.98 (dd, 3JHH = 7.9 Hz, 4JHH
=
4
1.5 Hz, 1 H, CHAr), 7.01 (d, JHH = 1.5 Hz, 1 H, CHAr), 7.40 (dd,
3JHP = 22.4 Hz, 3JHH = 17.4 Hz, 1 H, CHAr).
13C NMR (62.9 MHz, CDCl3): d = 16.01 (d, JCP = 6.4 Hz, 2 ×
3
2
CH3CH2OP), 61.34 (d, JCP = 5.5 Hz, 2 × CH3CH2OP), 101.20
(CH2O2Ar), 105.78 (CHAr), 108.02 (CHAr), 111.09 (d, 1JCP = 192.5
3
Hz, PCH), 123.54 (CHAr), 128.94 (d, JCP = 24.0 Hz, CAr), 147.92
(d, 2JCP = 5.7 Hz, CHAr), 147.97 (CAr), 149.14 (CAr).
31P NMR (101 MHz, CDCl3): d = 20.41.
Anal. Calcd for C13H17O5P: C, 54.93; H, 6.03. Found: C, 55.08; H,
6.10.
Diethyl (E)-2-(4-Hydroxyphenyl)vinylphosphonate (7a)
Yield: 82%; pale yellow oil.
IR (CCl4): 2980, 1604, 1512, 1208, 1168, 1024, 964, 808 cm–1.
Diethyl (E)-2-(4-Bromophenyl)vinylphosphonate (5g)3c
Yield: 82%; white crystals; mp 71–73 °C (Lit. 69–70 °C).
IR (CCl4): 2984, 1616, 1488, 1396, 1248, 1028, 964, 760 cm–1.
3
1H NMR (250 MHz, CDCl3): d = 1.35 (t, JHH = 7.0 Hz, 6 H, 2 ×
CH3CH2OP), 4.07–4.18 (m, 4 H, 2 × CH3CH2OP), 6.05 (dd, 3JHH
=
2
3
17.5 Hz, JHP = 17.5 Hz, 1 H, CHP), 6.91 (d, JHH = 8.5 Hz, 2 H,
3
1H NMR (250 MHz, CDCl3): d = 1.36 (t, JHH = 7.0 Hz, 6 H, 2 ×
2 × CHAr), 7.35 (d, 3JHH = 8.5 Hz, 2 H, 2 × CHAr), 7.42 (dd, 3JHP
=
CH3CH2OP), 4.08–4.20 (m, 4 H, 2 × CH3CH2OP), 6.25 (dd, 3JHH
=
22.9 Hz, 3JHH = 17.5 Hz, 1 H, CHAr).
2
3
17.5 Hz, JHP = 17.5 Hz, 1 H, CHP), 7.44 (d, JHH = 8.5 Hz, 2 H,
3
13C NMR (62.9 MHz, CDCl3): d = 16.20 (d, JCP = 6.5 Hz, 2 ×
2 × CHAr), 7.44 (dd, JHP = 22.8 Hz, 3JHH = 17.5 Hz, 1 H, CHAr),
3
CH3CH2OP), 62.05 (d, 2JCP = 5.5 Hz, 2 × CH3CH2OP), 108.14 (d,
7.52 (d, 3JHH = 8.5 Hz, 2 H, 2 × CHAr).
3
1JCP = 194.9 Hz, PCH), 115.97 (2 × CHAr), 125.98 (d, JCP = 23.8
Synthesis 2005, No. 17, 2887–2896 © Thieme Stuttgart · New York

PAPER
Knoevenagel Reaction of Diethylphosphonoacetic Acid
2895
2
Hz, CAr), 129.50 (2 × CHAr), 149.65 (d, JCP = 6.9 Hz, CHAr),
31P NMR (101 MHz, CDCl3): d = 21.33.
159.82 (CAr).
Anal. Calcd for C12H17O5P: C, 52.94; H, 6.29. Found: C, 53.08; H,
6.40.
31P NMR (101 MHz, CDCl3): d = 21.41.
Anal. Calcd for C12H17O4P: C, 56.25; H, 6.69. Found: C, 56.10; H,
6.60.
Diethyl (E)-2-(1H-Indol-3-yl)vinylphosphonate (7e)
Yield: 76%; brown oil.
Diethyl (E)-2-(3-Hydroxyphenyl)vinylphosphonate (7b)
Yield: 68%; yellow oil.
IR (CCl4): 2984, 1608, 1440, 1392, 1216, 1024, 960, 856, 800, 744
cm–1.
3
IR (CCl4): 2980, 1588, 1452, 1292, 1240, 1040, 856, 780 cm–1.
1H NMR (250 MHz, CDCl3): d = 1.42 (t, JHH = 7.2 Hz, 6 H, 2 ×
CH3CH2OP), 4.14–4.26 (m, 4 H, 2 × CH3CH2OP), 6.20 (dd, 3JHH
=
3
1H NMR (250 MHz, CDCl3): d = 1.35 (t, JHH = 7.0 Hz, 6 H, 2 ×
17.5 Hz, 2JHP = 18.5 Hz, 1 H, CHP), 7.26–7.35 (m, 2 H, 2 × CHAr),
7.48–7.51 (m, 2 H, 2 × CHAr), 7.77 (dd, 3JHP = 23.2 Hz, 3JHH = 17.5
Hz, 1 H, CHAr), 7.93–7.97 (m, 1 H, CHAr), 9.08 (s, 1 H, NH).
CH3CH2OP), 4.08–4.21 (m, 4 H, 2 × CH3CH2OP), 6.24 (dd, 3JHH
=
2
3
17.5 Hz, JHP = 17.5 Hz, 1 H, CHP), 6.92 (d, JHH = 8.0 Hz, 1 H,
CHAr), 7.05 (d, 3JHH = 8.0 Hz, 1 H, CHAr), 7.18 (s, 1 H, CHAr), 7.21
(t, 3JHH = 8.0 Hz, 1 H, CHAr), 7.51 (dd, 3JHP = 23.0 Hz, 3JHH = 17.5
Hz, 1 H, CHAr).
13C NMR (62.9 MHz, CDCl3): d = 16.22 (d, JCP = 6.7 Hz, 2 ×
3
CH3CH2OP), 61.65 (d, 2JCP = 5.4 Hz, 2 × CH3CH2OP), 105.28 (d,
1JCP = 194.6 Hz, PCH), 112.22 (CHAr), 113.02 (d, JCP = 25.6 Hz,
3
3
13C NMR (62.9 MHz, CDCl3): d = 16.33 (d, JCP = 6.4 Hz, 2 ×
CAr), 119.65 (CHAr), 120.93 (CHAr), 122.67 (CHAr), 124.98 (CAr),
CH3CH2OP), 62.30 (d, 2JCP = 5.5 Hz, 2 × CH3CH2OP), 112.57 (d,
1JCP = 191.6 Hz, PCH), 114.99 (CHAr), 118.15 (CHAr), 118.80
(CHAr), 129.93 (CHAr), 135.70 (d, 3JCP = 23.5 Hz, CAr), 149.92 (d,
2JCP = 6.5 Hz, CHAr), 157.87 (CAr).
129.61 (CHAr), 137.47 (CAr), 143.40 (d, 2JCP = 6.7 Hz, CHAr).
31P NMR (101 MHz, CDCl3): d = 22.59.
Anal. Calcd for C14H18NO3P: C, 60.21; H, 6.50. Found: C, 60.41; H,
6.61.
31P NMR (101 MHz, CDCl3): d = 20.20.
Anal. Calcd for C12H17O4P: C, 56.25; H, 6.69. Found: C, 56.08; H,
6.62.
Diethyl Vinylphosphonate (9)16
A mixture of the acid 1 (3.92 g, 0.02 mol), dicyclohexylamine
(0.543 g, 0.003 mol), DABCO (0.336 g, 0.003 mol) and paraform-
aldehyde (1.32 g, 0.044 mol) in benzene (50 mL) was heated at re-
flux under a Dean–Stark water separator for 2 h. The solution was
filtered to remove the polymeric species and the filtrate was concen-
trated under vacuum. The resulting oily residue was dissolved in
CHCl3 (50 mL), washed with water (3 × 10 mL) and dried over
MgSO4. Removal of the solvent gave the crude product, which was
purified by vacuum distillation. Yield: 73%; colorless oil; bp 80–82
°C/15 mmHg (lit.16b bp 80–83/15 mmHg).
Diethyl (E)-2-(4-Hydroxy-3-methoxyphenyl)vinylphosphonate
(7c)
Yield: 80%; white crystals; mp 99–101 °C.
IR (CCl4): 2936, 1584, 1512, 1216, 1032, 968, 840, 760 cm–1.
3
1H NMR (250 MHz, CDCl3): d = 1.35 (t, JHH = 7.1 Hz, 6 H, 2 ×
CH3CH2OP), 3.92 (s, 3 H, CH3OAr), 4.10–4.18 (m, 4 H, 2 ×
CH3CH2OP), 6.06 (dd, 3JHH = 17.5 Hz, 2JHP = 17.5 Hz, 1 H, CHP),
3
4
6.91 (d, JHH = 8.1 Hz, 1 H, CHAr), 7.00 (d, JHH = 1.8 Hz, 1 H,
CHAr), 7.05 (dd, 3JHH = 8.1 Hz, 4JHH = 1.8 Hz, 1 H, CHAr), 7.42 (dd,
3JHP = 22.5 Hz, 3JHH = 17.5 Hz, 1 H, CHAr).
Acknowledgment
3
13C NMR (62.9 MHz, CDCl3): d = 15.98 (d, JCP = 6.5 Hz, 2 ×
2
Research project 3T09A07528 was financed from the government
budget for science in the years 2005–2007.
CH3CH2OP), 55.50 (CH3OAr), 61.57 (d, JCP = 5.5 Hz, 2 ×
1
CH3CH2OP), 109.10 (d, JCP = 194.1 Hz, PCH), 109.48 (CHAr),
3
114.92 (CHAr), 122.03 (CHAr), 126.41 (d, JCP = 23.8 Hz, CAr),
147.26 (CAr), 148.68 (CAr), 149.03 (d, 2JCP = 6.9 Hz, CHAr).
31P NMR (101 MHz, CDCl3): d = 20.71.
References
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H. O. Modern Synthetic Reactions, 2nd ed.; Benjamin, W.
A., Ed.; Mentlo Park: California, 1972, 646. (c) Deutsch, H.
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Anal. Calcd for C13H19O5P: C, 54.54; H, 6.69. Found: C, 54.41; H,
6.60.
Diethyl (E)-2-(3,4-Dihydroxyphenyl)vinylphosphonate (7d)
Yield: 79%; white crystals; mp 87–89 °C.
IR (CCl4): 2992, 1596, 1528, 1444, 1368, 1292, 1188, 1048, 976,
952, 784 cm–1.
3
1H NMR (250 MHz, CDCl3): d = 1.35 (t, JHH = 7.5 Hz, 6 H, 2 ×
CH3CH2OP), 4.06–4.18 (m, 4 H, 2 × CH3CH2OP), 6.04 (dd, 3JHH
=
(d) D’Onofrio, F.; Piancatelli, G.; Nicolai, M. Tetrahedron
1995, 51, 4083. (e) Kim, D. Y.; Rhie, D. Y. Tetrahedron
1997, 53, 13603. (f) Nagaoka, Y.; Tomioka, K. J. Org.
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Shapiro, G.; Pombo-Villar, E. J. Org. Chem. 2000, 65,
2
3
17.4 Hz, JHP = 19.2 Hz, 1 H, CHP), 6.90 (d, JHH = 8.2 Hz, 1 H,
CHAr), 6.98 (dd, 3JHH = 8.2 Hz, 4JHH = 2.0 Hz, 1 H, CHAr), 7.18 (d,
4JHH = 2.0 Hz, 1 H, CHAr), 7.43 (dd, 3JHP = 23.0 Hz, 3JHH = 17.4 Hz,
1 H, CHAr).
3
13C NMR (62.9 MHz, CDCl3): d = 16.09 (d, JCP = 6.7 Hz, 2 ×
CH3CH2OP), 62.28 (d, 2JCP = 5.6 Hz, 2 × CH3CH2OP), 107.87 (d,
1JCP = 195.3 Hz, PCH), 114.21 (CHAr), 115.42 (CHAr), 121.32
(CHAr), 126.73 (d, 3JCP = 24.0 Hz, CAr), 144.84 (CAr), 147.60 (CAr),
150.24 (d, 2JCP = 6.5 Hz, CHAr).
Synthesis 2005, No. 17, 2887–2896 © Thieme Stuttgart · New York

2896
H. Krawczyk, Ł. Albrecht
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Synthesis 2005, No. 17, 2887–2896 © Thieme Stuttgart · New York