Efficient synthesis of stable phosphonate ylides and phosphonate esters: Reaction between activated acetylenes and triphenylphosphite in the presence of sulfonamide and heterocyclic NH-Acids

Article abstract of DOI:10.2174/1386207311107010002

An efficient synthesis of stable phosphonate ylides and phosphonate esters is described via a one-pot reaction between activated acetylenes and triphenylphosphite in the presence of sulfonamides and heterocyclic NH-acids. Single X-ray diffraction analysis

Full text of DOI:10.2174/1386207311107010002

2
Combinatorial Chemistry & High Throughput Screening, 2011, 14, 2-8
Efficient Synthesis of Stable Phosphonate Ylides and Phosphonate Esters:
Reaction Between Activated Acetylenes and Triphenylphosphite in the
Presence of Sulfonamide and Heterocyclic NH-Acids
Faramarz Rostami Charati*,1, Malek Taher Maghsoodlou2, Sayyed Mostafa Habibi-Khorassani2,
Nourallah Hazeri2, Ali Ebrahimi2, Zinatossadat Hossaini3, Pouneh Ebrahimi1, Nariman Maleki2,
Sayyed Reza Adhamdoust2, Fatemeh Vasheghani-Farahani2, Ghasem Marandi2, Alexandre Sobolev4
and Mohamed Makha4
1Faculty of Basic Science, Gonbad Institutes of Higher Education, P.O. Box 163, Gonbad, Iran
2Department of Chemistry, The University of Sistan and Baluchestan, P.O. Box 98135-674, Zahedan, Iran
3Department of Chemistry, Islamic Azad University, Qaemshahr Branch, P.O.Box 163, Qaemshahr, Iran
4School of Biomedical, Biomolecular and Chemical Sciences, M310, University of Western Australia, Perth, WA 6009,
Australia
Abstract: An efficient synthesis of stable phosphonate ylides and phosphonate esters is described via a one-pot reaction
between activated acetylenes and triphenylphosphite in the presence of sulfonamides and heterocyclic NH-acids. Single
X-ray diffraction analysis and NMR studies were used in characterizing the ylides and phosphonate ester products.
Dynamic NMR studies performed on a phosphonate ylide allowed the calculation of the free energy barrier for the inter-
conversion between the geometrical isomers (E) and (Z).
Keywords: Dialkyl acetylenedicarboxylates, sulfonamide NH-acids, heterocyclic NH-acids, triphenylphosphite, phosphonate
ylide, dynamic NMR.
1. INTRODUCTION
procedure for direct synthesis of stable phosphonate ylides, 4
from the reaction of triphenylphosphite 1 and acetylenic
esters 2 in the presence of sulfonamides 3 at ambient
temperature in diethyl ether as a solvent (Scheme 1). The
major product is the phosphonate ylide 4 and then followed
by the hydrolysis reaction leads to the phosphonate esters 5.
Phosphorus ylides are important class of organic
compounds due to their applications in organic synthesis [1-
6], especially for the preparation of naturally occurring
products of biological and pharmacological activity [7-18].
Phosphorus ylides chemistry has contributed to the
development of modern synthetic chemistry of naturally and
physiologically active molecules [18]. These compounds are
widely used reagents as synthetic building blocks in the
formation of carbon-carbon double bonds. This has
awakened interest in the study of the synthesis, structure and
properties of phosphorus ylides and their derivatives [19]. In
the course of our investigations to develop syntheses of
organophosphorus compounds [20-30], we successfully
synthesised a new class of stable phosphonate ylides, 4
which was undertaken from the reaction between
triphenylphosphite 1 and acetylenic esters 2 in the presence
of sulfonamides 3. Subsequently, the hydrolysis of the
The structures of compounds 4 and 5 were assigned by
IR, 1H NMR, 13C NMR, 31P NMR and mass spectral data and
confirmed by X-ray diffraction. The 1H NMR spectrum of 4a
exhibited two singlets at 3.57 and 3.63 ppm arising from
methoxy protons and a doublet at ꢀ = 6.2 (3JPH = 6.0 Hz) for
the methine proton, along with multiplets at ꢀ = 6.91-7.20 for
the aromatic protons. The carbonyl groups resonances in the
13C NMR spectra of 4a appear at ꢀ = 167.0 (d, 3JPC = 6.8 Hz)
2
and 169.0 (d, JPC = 8.2 Hz) ppm. The mass spectrum of 4a
displayed the molecular ion peak at m/z = 685, which are
consistent with the 1:1:1 adduct of dimethyl acetyl-
enedicarboxylate, triphenylphosphite, and sulfonamide. The
structure of 4a was further confirmed by a single crystal X-
ray diffraction analysis (Fig. 1). The 1H and 13C NMR
spectra of compounds 4b and 4c are similar to those of 4a,
except for the aromatic moiety, which exhibited character-
istic signals with appropriate chemical shifts (see experi-
mental). Moreover, The structure of 4b was further con-
firmed by a single crystal X-ray diffraction analysis (Fig. 1).
phosphonate ylides,
phosphonate esters, 5 in excellent yields.
4
afforded the corresponding
2. RESULTS AND DISCUSSION
As part of our current studies on the development of new
routes in heterocyclic synthesis, we report an efficient
1
The H NMR spectrum of 5c exhibited two singlets at
3.54 and 3.60 ppm arising from methoxy protons, two
doublet of doublet at the ꢀ = 3.75 (dd, 1H, 2JPH= 17 Hz, 3JHH
= 12 Hz), and ꢀ = 5.72 (dd, 1H, 3JPH= 15 Hz, 3JHH = 1.5 Hz),
for methine proton, along with multiplets at ꢀ = 6.91-7.70
*Address correspondence to this author at the Faculty of Basic Science,
Gonbad Institutes of Higher Education, P.O. Box 163, Gonbad, Iran;
Tel: 0172-2225021; Fax: 0172-2224060;
E-mails: f_rostami_ch@yahoo.com, frostami@gau.ac.ir
1386-2073/11 $58.00+.00
© 2011 Bentham Science Publishers Ltd.

Synthesis of Stable Phosphonate Ylides and Phosphonate Esters
Combinatorial Chemistry & High Throughput Screening, 2011, Vol. 14, No. 1 3
X
X
X
CO2Me
PhO
O
P
SO2
SO2
Ar
PhO
PhO
PhO
H2O
Ar
Dry Et2O, r.t.
H
P
N
O
S
N
(PhO)3P
+
+
Ar
PhO
- PhOH
N
H
O
C
H
H
CO2Me
MeO2C
CO2Me
MeO2C
CO2Me
4
5
3
1
2
Ar
X
%Yield of 4, 5
4, 5
a
b
c
Phenyl
Phenyl
2,6-dimethylphenyl
H
CH3
H
85, 80
90, 85
95, 90
Scheme 1. Reaction between triphenylphosphite and acetylenic esters in the presence of sulfonamides.
ppm for the aromatic protons. The carbonyl groups
addition of water to the reaction mixture. Since the reactions
were carried out under an ordinary atmosphere, the
conversion of ylide 4 to phosphonate ester 5 can also be
accomplished by hydrolysis from moisture in air or under
chromatographic conditions.
resonances in the 13C NMR spectra of 5c appear at ꢀ = 165.3
2
2
(d, JCP = 5.5 Hz) and 169.3 (d, JCP = 2.5 Hz) ppm. The
structure of 5c was further confirmed by a single crystal X-
ray diffraction analysis (Fig. 1).
Under similar reaction conditions, the reaction between
activated acetylenes 2 and heterocyclic NH-acids 6 in the
presence of triphenylphosphite, 1 as a nucleophile leads to
functionalized phosphonate ylides 7 in good yields (Scheme
3).
The 1H NMR spectrum of 7a in CDCl3 shows two
singlets at ꢀ = 3.57 and 3.65 ppm for the methoxy protons
and a doublet at ꢀ = 6.02 (3JPH = 16.9 Hz) for the methine
proton, along with multiplets at ꢀ = 6.98–9.20 for the
aromatic protons. At ambient temperature, the 1H NMR
spectrum of 7a in CDCl3 exhibits two sets of methoxy
resonances at 3.21 and 3.72 ppm and at 3.09 and 3.77 ppm
with a relative intensity ratio of ca. 3:1. As the temperature
was increased, broadening of the signals occurred
(coalescence temperature, 295 ± 1 K). Although an extensive
line-shape analysis in relation to the dynamic 1H NMR effect
observed for 7a was not undertaken, the variable temperature
spectra allowed the calculation of the free energy barrier for
the dynamic NMR process in 7a. From coalescence of the O-
Me proton resonances and using the expression, k = ꢁꢁꢂ/ꢂ2,
the first-order rate constant (k) for the dynamic NMR effect
in 7a was calculated to be 55.53 s-1 at 295 K (Table 1).
Application of the absolute rate theory with a transmission
coefficient of 1 gives a free-energy of activation (ꢁG#) of
62.28 ± 2 kJ.mol-1, where all known sources of errors are
estimated and included [34].
Fig. (1). ORTEP representation of the molecular structure of 4a, 4b
and 5c.
Although we have not established the mechanism of the
reaction between the triphenylphosphite and the acetylenic
The E–Z isomerism of ylides possessing a carbonyl group at
the ꢃ-position has been observed previously [10, 35, 36].
Further evidence for the presence of the ylide ester group in 7a
was based on the observation of a strong low-frequency
carbonyl absorption at 1667 cm-1 in the IR spectrum [10]. The
other ester carbonyl absorption in 7a appears at 1722 cm-1. The
13C and 31P NMR spectra of 7a also confirmed the presence of
two rotational isomers at ambient temperature. Thus, the 13C
NMR spectrum consisted of two sets of signals that comprised
more than 50 resonances in total. Characteristic carbonyl
esters in the presence of sulfonamide derivatives
3
experimentally, a possible explanation is proposed in
Scheme 2. The initial step may involve addition of
triphenylphosphite to the acetylenic ester [31-33], and
formation of the 1:1 adducts I which protonated by
sulfonamide to give a transition state II. Subsequently, the
positively charged ion II is attacked by the anion of the NH-
acid 3 to produce ylide 4, which is hydrolyzed to give
phosphonate ester 5. The hydrolysis of ylide 4 to the
corresponding phosphonate ester 5 can be achieved by

4
Combinatorial Chemistry & High Throughput Screening, 2011, Vol. 14, No. 1
Charati et al.
(PhO)3P
RO2C
(PhO)3P
3
C
C
CO2R
C
C
CO2R
H
1
+
2
RO2C
II
I
O
O
Ar
S
N
H2O
-PhOH
5
4
X
Scheme 2. Proposed mechanism for the reaction of triphenylphosphite and acetylenic esters in the presence of sulfonamides.
CO2R
PhO
PhO
PhO
Z
P
Dry Et2O, r.t.
(PhO)3P
Z-H
+
+
H
RO2C
CO2R
CO2R
6
7
7
1
2
Z
R
%Yield
O
a
b
c
92
90
85
Me
Et
O
S
But
N
O
N
97
d
Me
Scheme 3. Reaction between triphenylphosphite and acetylenic esters in the presence of NH-acids.
resonances appear clearly at ꢀ = 173.1, 168.4 (d, 2JPC = 17 Hz)
and 169.4 (d, 2JPC = 18 Hz) ppm, whereas the ylide carbon atom
exhibits resonances at ꢀ = 41.1 (d, 1JPC = 225 Hz) and 41.2 (d,
1JCP = 223 Hz) ppm. The observed 1JCP values are typical of an
ꢁ-ylide ester [11]. The double bond character of the C–P bond
and the presence of three electronegative oxo substituents on the
phosphorus atom increases the 1JCP value [37].
3. CONCLUSION
In conclusion, we have found that the reaction of Dialkyl
acetylenedicarboxylates with triphenylphosphite in the
presence of several NH-acid leads to a facile synthesis of
some functionalized phosphonate ylieds and phosphonate
esters. Also, dynamic NMR effect is observed in the 1H
NMR spectra of some phosphonate ylides. The present
Table 1. Selected Proton Chemical Shifts (at 500.1 MHz, in ppm, Me4Si) and Calculated Activation Parameters (kJ.mol-1) for 7a in
CDCl3
Compound Temp (˚C)
ꢀ (OMe)
ꢀ (CH)
ꢁꢂ (Hz)
k (s-1) TC (K) ꢁGꢃ (kJ. mol-1) ꢁHꢃ (kJ. mol-1)
ꢁSꢃ (kJ. mol-1)
7a
7
2
3.57 3.62
----
----
25
35
55.53
77.74
295
290
62.28 ± 2
60.37 ± 2
48.82 ± 2
-0.376 ± 2
5.94 6.01

Synthesis of Stable Phosphonate Ylides and Phosphonate Esters
Combinatorial Chemistry & High Throughput Screening, 2011, Vol. 14, No. 1 5
O
P
OMe
CO2Me
MeO
P
O
PhO
PhO
PhO
PhO
CO2Me
H
H
PhO
N
O
PhO
N
O
O
O
(Z)-7a
(E)-7a
Scheme 4. Geometrical isomers (E)-7a and (Z)-7a.
method is advantageous because the reaction is performed
under neutral conditions and the reagents can be used
without prior activation or modification.
C--CH), 6.90-7.20 (25Harom, 5C6H5). 13C NMR (125.8 MHz,
1
CDCl3), ꢂC 43.12 (d, JPC = 226.03 Hz P+-C-), 53.21 and
52.40 (2OCH3), 55.20 (d, 2JPC = 15.01 Hz, P+-C--CH), 113.5,
3
115.9, 121.02 (d, JPC = 4.5 Hz, Cortho), 127.3 (Cpara), 129.1
2
(Cmetha), 130.2, 138.4, 139.7, 152.3 (d, JPC = 6.2 Hz, Cipso),
Material and Methods
167.0 (d, 3JPC = 6.8 Hz, C=O), 169.0 (d, 2JPC = 8.2 Hz, C=O):
31P NMR (202.5 MHz, CDCl3): ꢂP 40.70 [(PhO)3P+-C-].
Melting points were measured on an Electrothermal 9100
apparatus. Elemental analyses for C, H, and N were
performed using a Heraeus CHN-O-Rapid analyzer. Mass
spectra were recorded on a FINNIGAN-MATT 8430
spectrometer operating at an ionization potential of 70 eV.
The X-ray diffracted intensities were measured from a
single crystal 0.40 x 0.36 x 0.32 mm at about 100 K on an
Oxford Diffraction Xcalibur-S CCD diffractometer using
monochromatized Cu-Kꢃ (ꢀ = 0.71073 Å). Data were
corrected for Lorentz and polarization effects and absorption
correction applied using multiple symmetry equivalent
reflections. The structure were solved by direct method and
refined on F2 using SHELX-97 crystallographic package. A
full matrix least-squares refinement procedure was used,
IR spectra were measured on
a Shimadzu IR-460
spectrometer. H, 13C, and 31P NMR spectra were measured
with a BRUKER DRX-500 AVANCE spectrometer at 500.1,
125.8, and 202.4 MHz, respectively. 1H, 13C, and 31P spectra
were obtained for solutions in CDCl3 using TMS as internal
standard or 85% H3PO4 as external standard. All the
chemicals used in this work were purchased from Fluka
(Buchs, Switzerland) and were used without further
purification.
1
2
2
2
minimizing w(Fo -Fc ), with w = [ꢀ2(Fo )+(AP)2+BP]-1,
2
2
where P= (Fo +2Fc )/3. Agreement factors (R = ꢀ||Fo|-
2
2 2
2 2
|Fc||/ꢀ|Fo|, wR2 = {ꢀ[w(Fo -Fc ) ]/ꢀ[w(Fo ) ]}1/2 and GOF =
{ꢀ[w(Fo -Fc ) ]/(n-p)}1/2 are cited, where n is the number of
reflections and p the total number of parameters refined). All
non-hydrogen atoms were refined anisotropically. Positions
of hydrogen atoms were localized from difference Fourier
synthesis and their atomic parameters were constrained to
the bonded atoms during the refinement.
2
2 2
These results were rationalized on the basis of the
presence of geometrical isomers (E)-7a and (Z)-7a (see
Scheme 4) that undergo rapid interconversion at 295 K.
General Procedure
To
a magnetically stirred a solution of dialkyl
Crystal/Refinement Details
acetylendicarboxylate 2 (2 mmol) and sulfonamide 3 (2
mmol) was added triphenylphosphite (0.62 g, 2 mmol) 1
slowly at room temperature in dry diethyl ether as a solvent.
The reaction mixture was stirred for 2 hours at room
temperature. The resultant precipitate was collected and
washed with cooled n-Hexane and diethyl ether (3ꢀ5 mL) to
yield the phosphonate ylide 4. The phosphonate ester 5 is
resulted if few drops of distilled water added to the reaction
mixture after 2 hours reaction or by leaving the reaction
mixture exposed to air for a week. The work-up followed
removal of the solvent under reduced pressure and the
resultant yellow residue was collected and crystallized from
ether/n-Hexane (4:1).
C36H32NO9PS, M = 685.66, F(000) = 2864 e, monoclinic,
C2/c (No. 15), Z = 8, T = 100(2) K, a = 22.7564(2), b =
21.5187(2), c = 15.4042(1) Å, ꢀ = 120.563(1) °, V =
6495.27(9) Å3; Dc = 1.402 g cm-3; sinꢁ/ꢁmax = 0.7035;
N(unique) = 9469 (merged from 102564, Rint = 0.0281, Rsig
=
0.0199), No (I > 2ꢂ(I)) = 7234; R = 0.0406, wR2 = 0.1119
(A,B = 0.08, 3.50), GOF = 1.007; |ꢂꢃmax| = 0.47(6) e Å-3.
CCDC 729585
Dimethyl 2-(N-p-Toluenesulfonyl-N-Phenyl-3-yl)-3-(Tri-
phenoxyphosphanylidene) Butandioate (4b)
White powder, yield 70, R (KBr) (ꢁmax, cm-1): 1755,
1650(C=O). NMR (500.1 MHz, CDCl3): 2.4 (s, -CH3), 3.50
and 3.68 (6H, 2s, 2OCH3), 62.3 (1H, d, 3JPH = 7.4 Hz, P+-C--
CH), 6.80-7.30 (24Harom, 5C6H5).
Dimethyl
2-(2-Oxo-2,3-Dihydro-1,3-Benzoxazol-3-yl)-3-
(Triphenoxyphosphanylidene) Butandioate (4a)
White powder, yield 85%, mp 140-142ºC, IR (KBr) (ꢁmax
,
The X-ray diffracted intensities were measured from a
single crystal (4b) of 0.26 x 0.15 x 0.07 mm at about 100 K
on an Oxford Diffraction Gemini-R Ultra CCDC diffract
meter using a Mo-Kꢃ (ꢀ = 0.71073 Å.) Data were corrected
for Lorentz and polarization effects and analytical absorption
correction. The structure were solved by direct method and
cm-1): 1745, 1638 (C=O). MS, (m/z, %): 685 (M+, 5), 592
(M+- OPh, 90), 499(M+-2Oph, 55), 406 (-P(OPh)3), 60. Anal.
Calcd for C36H32NO9PS C, 63.06; H, 4.70; N, 2.04, Found:
1
C, 63.1; H, 4.77; N, 2.12. H NMR (500.1 MHz, CDCl3):
3.57 and 3.63 (6H, 2s, 2OCH3), 6.2 (1H, d, 3JPH = 6.0 Hz, P+-

6
Combinatorial Chemistry & High Throughput Screening, 2011, Vol. 14, No. 1
Charati et al.
refined on F2 using SHELX-97 crystallographic package. A
of C6H5), 125.6, 125.7 (2 Cpara of 2C6H5), 128.4, 128.5
full matrix least-squares refinement procedure was used,
(2Cmeta of 2C62H5), 129.3, 129.6, 129.7, 129.9, 133.1 135,
3
2
2
2
minimizing w(Fo -Fc ), with w = [ꢀ2(Fo )+(AP)2+BP]-1,
139, 150.0 (d, JCP = 9.6 Hz, Cipso of C6H5), 150.2 (d, JCP
=
2
2
2
where P= (Fo +2Fc )/3. Agreement factors (R = ꢁ||Fo|-
9.4 Hz, Cipso of C6H5), 166.0 (d JCP = 6.7 Hz, C=O ester),
168.4 (s, C=O ester), 31P NMR (202.4 MHz, CDCl3): ꢅ 11.8
[-(PhO)231PO].
|Fc||/ꢁ|Fo|, wR2 = {ꢁ[w(Fo -Fc ) ]/ꢁ[w(Fo ) ]}1/2 and GOF =
2
2 2
2 2
{ꢁ[w(Fo -Fc ) ]/(n-p)}1/2 are cited, where n is the number of
reflections and p the total number of parameters refined). All
non-hydrogen atoms were refined anisotropically. The
positions of hydrogen atoms were localized from difference
Fourier synthesis and refined with constrains to the bonded
atoms.
2
2 2
Dimethyl-N-(1,6-Dimethylphenylsulfonamino-N-yl)-3-(Di-
phenoxyphosphoryl) Butenedioate (5c)
Colurless crystals, 0.53 g, yield 70%, m.p. 168-170 ºC. IR
(KBr) (ꢄmax, cm-1): 2951 (SO2), 1781 and 1750 (2 C=O of
esters), 1591 (C=C). MS, (m/z, %): 637 (M+, 80), 544 (M+-
OPh, 95), 45160 (M+-2Oph, 55). Anal. Calcd for
C32H32NO9PS C, 60.28; H, 5.06; N, 2.20; Found: C, 60.65;
C37H34NO9PS, M = 699.68, F(000) = 732 e, triclinic, P-1
(No. 2), Z = 2, T = 100(2) K, a = 10.7430(4), b = 10.8875(4),
c = 15.1457(9) Å, ꢀ = 105.338(4), ꢁ = 96.991(4), ꢂ =
99.420(3) °, V = 1659.83(13) Å3; Dc = 1.400 g cm-3;
sinꢃ/ꢂmax = 0.6497; N(unique) = 7595 (merged from 38528,
Rint = 0.0744, Rsig = 0.0930), No (I > 2 ꢀ(I)) = 4587; R =
0.1188, wR2 = 0.3575 (A,B = 0.06, 42.5), GOF = 1.006;
|ꢃ max| = 1.5(2) e Å-3, CCDC 715538.
1
H, 5.40; N, 2.18. H NMR (500.1 MHz, CDCl3): 1.78, 1.79
(2ꢆs, 6H, 2CH3), 3.5(s, 3H, OCH3), 3.6 (s, 3H, OCH3), 3.75
2
3
3
(dd, 1H, JPH = 17 Hz, JHH = 12 Hz), 5.7 (dd, 1H, JPH = 15
Hz, JHH = 1.5 Hz), 6.9-7.7 (m, 18H, Aromatic region). 13C
3
NMR (75 MHz, CDCl3): ꢅ 18.7, 19.7 (2ꢆs, 2CH3), 46.5 (d,
1JCP = 130.9 Hz, P-13CH), 52.6, 52.9 (2ꢆs, 2OCH3), 60.4 (d,
3
2JCP = 4 Hz, P-CH-13CH), 120.3 (d, JCP = 4.9 Hz, Cortho of
Dimethyl 2-(N-Benzensulfonyl-N-2,6 Dimethyl phenyl-3-
yl)-3-(Triphenoxyphosphanylidene) Butandioate (4c)
3
C6H5), 120.6, 121 (d, JCP = 4.3 Hz, Cortho of C6H5), 125.5,
125.6 (2 Cpara of 2C6H5), 128.4, 129.0 (2Cmeta of 2C6H5),
129.4, 129.5, 129.8, 130.1, 132.9, 134.2, 137.9, 140.1, 141.9,
IR (KBr) (ꢄmax, cm-1): 1745, 1655 (C=O). NMR (500.1
MHz, CDCl3): 2.4 and 2.6 (2 CH3), 3.2 and 3.8 (6H, 2s,
142.4, 149.9 (d, 2JCP = 7.7 Hz, Cip2so of C6H5), 150.5(d, 3JCP
=
3
2OCH3), 6.2 (1H, d, JPH = 6.0 Hz, P+-C--CH), 6.90-7.20
9.5 Hz, Cipso of C6H5), 165.3 (d JCP = 5.5 Hz, C=O ester),
169.3 (s, C=O ester).
(23Harom).
Dimethyl-N-(Phenylsulfonamino-N-yl)-3-(Diphenoxyphos-
phoryl)Butanedioate (5a)
X-Ray Crystallography (5c): Crystal/Refinement Details
The X-ray diffracted intensities were measured from a
single crystal (5c) of 0.33 x 0.23 x 0.11 mm at about 100 K
on an Oxford Diffraction Xcalibur-S CCDC diffractometer
using monochromatized Mo-Kꢇ (ꢄ = 0.71073 Å.) Data were
corrected for Lorentz and polarization effects and absorption
correction applied using multiple symmetry equivalent
reflections. The structure were solved by direct method and
refined on F2 using SHELX-97 crystallographic package. A
full matrix least-squares refinement procedure was used,
Colorless crystals, 0.53 g, yield 70%, m.p. 125-127 ºC. IR
(KBr) (ꢄmax, cm-1): 2946 (SO2), 1745, 1638 (2 C=O of
esters), 1588 (C=C). MS, (m/z, %): 609 (M+, 100). Anal.
Calcd for C30H28NO9PS C, 59.11; H, 4.63; N, 2.30; Found:
1
C, 59.18; H, 4.71; N, 2.24. H NMR (500.1 MHz, CDCl3):
2
3.6 (s, 3H, OCH3), 3.8(s, 3H, OCH3), 3.99 (dd, 1H, JPH
=
=
3
3
3
22.5 Hz, JHH = 11.5 Hz), 5.9 (dd, 1H, JPH = 8.8 Hz, JHH
11.5 Hz), 7.0 - 7.4 (m, 20H, Aromatic region). 13C NMR (75
MHz, CDCl3): ꢅ 48.4 (d, JCP = 130.5 Hz, P-13CH), 52.6,
1
2
2
2
minimizing w(Fo -Fc ), with w = [ꢀ2(Fo )+(AP)2+BP]-1,
53.2 (2ꢆs, 2OCH3), 60.9 (d, JCP = 2.6 Hz, P-CH-13CH),
2
2
2
where P= (Fo +2Fc )/3. Agreement factors (R = ꢁ||Fo|-
3
3
120.2 (d, JCP = 4.5 Hz, Cortho of C6H5) 120.6, 120.7 (d, JCP
= 4.5 Hz, Cortho of C6H5), 125.6, 125.7 (2 Cpara of 2C6H5),
128.4, 128.5 (2Cmeta of 2C6H5), 129.3, 129.6, 129.7, 129.9,
133.1 135, 139, 150.0 (d, 2JCP = 9.6 Hz, Cipso of C6H5), 150.2
(d, 3JCP = 9.4 Hz, Cipso of C6H5), 166.0 (d 2JCP = 6.7 Hz, C=O
ester), 168.4 (s, C=O ester), 31P NMR (202.4 MHz, CDCl3):
ꢅ 11.5 [-(PhO)231PO].
|Fc||/ꢁ|Fo|, wR2 = {ꢁ[w(Fo -Fc ) ]/ꢁ[w(Fo ) ]}1/2 and GOF =
2
2 2
2 2
2
2 2
{ꢁ[w(Fo -Fc ) ]/(n-p)}1/2 are cited, where n is the number of
reflections and p the total number of parameters refined). All
non-hydrogen atoms were refined anisotropically using all
reflections. Positions of hydrogen atoms were localized from
difference Fourier synthesis and their atomic parameters
were constrained to the bonded atoms during refinement.
Dimethyl-N-(Methylphenylsulfonamino-N-yl)-3-(Diphenoxy-
phosphoryl)Butanedioate (5b)
C32H32NO9PS, M = 637.62, F(000) = 1336 e, triclinic, P-
1 (No. 2), Z = 4, T = 100(2) K, a = 8.2746(1), b =
16.2970(2), c = 23.2316(4) Å, ꢀ = 80.451(1), ꢁ = 89.518(1),
Colorless crystals, 0.53 g, yield 70%, m.p. 125-127 ºC. IR
(KBr) (ꢄmax, cm-1): 2946 (SO2), 1745, 1638 (2 C=O of
esters), 1588 (C=C). MS, (m/z, %): 623 (M+, 80), 530 (M+-
OPh, 40). Anal. Calcd for C31H30NO9PS C, 59.71; H, 4.85;
N, 2.25;, Found: C, 59.80; H, 4.80; N, 2.19.
ꢄ= 87.915(1) °, V = 3087.35(8) Å3; Dc = 1.372 g cm-3; ꢅMo
=
0.213 mm-1; sinꢃ/ꢂmax = 0.7035; N(unique) = 17954 (merged
from 91069, Rint = 0.0516, Rsig = 0.0669), No (I > 2 ꢀ(I)) =
12181; R = 0.0690, wR2 = 0.1781 (A,B = 0.04, 4.7), GOF =
1.002; |ꢃ max| = 0.89(8) e Å-3, CCDC 715537.
1H NMR (500.1 MHz, CDCl3): 2.3 (s, 3H, -CH3), 3.6 (s,
3H, OCH3), 3.8 (s, 3H, OCH3), 3.99 (dd, 1H, 2JPH = 22.5 Hz,
General Procedure for Preparation of Compound 7a
3
3JHH = 11.5 Hz), 5.9 (dd, 1H, JPH = 8.8 Hz, 3JHH = 11.5 Hz),
7.0 - 7.4 (m, 19H, Aromatic region). 13C NMR (75 MHz,
To a magnetically stirred solution of 2-benzoxazolinone
(0.28 g, 2mmol) and triphenylphosphite (0.62 g, 2 mmol) in
10 mL of dry diethyl ether, dimethyl acetylenedicarboxylate
(0.28 g, 2 mmol) was added slowly. After approximately 2-3
CDCl3): ꢅ 48.4 (d, 1JCP = 130.5 Hz, P-13CH), 52.6, 53.2 (2ꢆs,
2
3
2OCH3), 60.9 (d, JCP = 2.6 Hz, P-CH-13CH), 120.2 (d, JCP
= 4.5 Hz, Cortho of C6H5) 120.6, 120.7 (d, 3JCP = 4.5 Hz, Cortho

Synthesis of Stable Phosphonate Ylides and Phosphonate Esters
Combinatorial Chemistry & High Throughput Screening, 2011, Vol. 14, No. 1 7
h stirring at room temperature, the product was filtered and
washed with cold diethyl ether (3ꢀ5 mL) and it was obtained
Dimethyl 2-(2-Thioxo-2, 3-Dihydro-1, 3-Benzoxazole-3-yl)-
3-(Triphenoxyphosphanylidene)Succinate (7d)
as:
º
White powder, yield 97%; mp 136-138 C, IR (KBr)
(ꢁmax, cm-1): 1751 and 1666 (C=O). MS, (m/z, %): 603 (M+,
2), 510 (M+-OPh, 76), 417 (M+-2Oph, 65), 310 (P(OPh)3,
50). Anal. Calcd for C31H26NO8PS C, 61.57; H, 4.28; N,
Dimethyl 2-(2-Oxo-2,3-Dihydro-1,3-Benzoxazol-3-yl)-3-(Tri-
phenoxyphosphanylidene)Butandioate (7a)
º
1
White powder, yield 92%, mp 126-128 C, IR (KBr)
2.39, Found: C, 61.69; H, 4.31; N, 2.32. H NMR (500.1
(ꢁmax, cm-1): 1766, 1748 and 1661 (C=O). MS, (m/z, %):
587(M+, 4), 494 (M+- OPh, 87), 401(M+-2Oph, 74), 310 (
P(OPh)3, 59). Anal. Calcd for C31H26NO9P C, 63.41; H, 4.52;
MHz, CDCl3): 3.58 and 3.68 (6H, 2s, 2OCH3), 6.84 (1H, d,
3JPH = 19.8 Hz, P+-C--CH), 6.90-7.32 (19Harom, m, 3C6H5 and
C7H4NOS). 13C NMR (125.8 MHz, CDCl3), ꢂC 45.11 (d, 1JPC
1
= 225.2 Hz, P+-C-), 53.16 and 53.47 (2OCH3), 53.63 (d, JPC
2
N, 2.37, Found: C, 63.37; H, 4.43; N, 2.40. H NMR (500.1
= 11.3 Hz, P+-C--CH), 110.28 and 110.51 (2C, C7H4NOS),
MHz, CDCl3): 3.57 and 3.65 (6H, 2s, 2OCH3), 6.02 (1H, d,
3JPH = 17.0 Hz, P+-C--CH), 6.91-7.21 (19Harom, 3C6H5 and
3
120.66 (d, JPC = 4.7 Hz, Cortho), 124.51 and 125.20 (2C,
C7H4NOS), 125.84 (Cpara), 129.92 (Cmetha), 130.12 and
147.16 (2C, C7H4NOS), 150.08 (d, JPC = 7.3 Hz, Cipso),
167.33 (d, JPC = 20.5 Hz, C=O), 168.53 (d, JPC =17.9 Hz,
C=O), 179.87(1C, C7H4NOS) : 31P NMR (202.5 MHz,
CDCl3): ꢂP 42.43 [(PhO)3P+-C-].
C7H4NO2). 13C NMR (125.8 MHz, CDCl3), ꢂC 44.79 (d, JPC
1
= 230.2 Hz P+-C-), 50.44 and 52.60 (2OCH3), 55.18 (d, JPC
2
2
= 13.8 Hz, P+-C--CH), 109.07 and 112.98 (2C, C7H4NO2),
2
3
3
120.08 (d, JPC = 4.5 Hz, Cortho), 121.71 and 123.82 (2C,
C7H4NO2), 126.08 (Cpara), 129.34 (1C, C7H42NO2), 129.83
(Cmetha), 142.23 (1C, C7H4NO2), 149.68 (d, JPC =7.4 Hz,
2
Crystallographic data (excluding structure factors) for the
structures in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supplementary
publications CCDC 729585, 715538 and 715537 for 4a, 4b
and 5c respectively. Copies of the data can be obtained, free
of charge, on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK, (fax: +44-(0)1223-336033 or e-
mail: deposit@ccdc.cam.ac.uk), or via www.ccdc.cam.ac.uk/
data_request/cif
C
ipso), 154.32 (1C, C7H4NO2), 168.27 (d, JPC = 21.4 Hz,
C=O), 169.24 (d, JPC = 17.6 Hz, C=O): 31P NMR (202.5
3
MHz, CDCl3): ꢂP 41.88 [(PhO)3P+-C-].
Diethyl 2-(2-Oxo-2,3-Dihydro-1,3-Benzoxazol-3-yl)-3-(Tri-
phenoxyphosphanylidene)Butandioate (7b)
º
White powder, yield 90%; mp 139-141 C, IR (KBr)
(ꢁmax, cm-1): 1766, 1740 and 1659 (C=O). Anal. Calcd for
C33H30NO9P C, 63.92; H, 4.95; N, 2.31, Found: C, 64.39; H,
4.88; N, 2.28. H NMR (500.1 MHz, CDCl3): 1.14 and 1.18
1
3
ACKNOWLEDGEMENTS
(6H, 2t, JHH = 6.5 Hz 2OCH2CH3), 4.03 and 4.15 (4H, m,
2ABX3 system 2OCH2CH3), 6.03 (1H, d, 3JPH = 16.6 Hz, P+-
C--CH), 6.90-7.18 (19Harom, m, 3C6H5 and C7H4NO2). 13C
NMR (125.8 MHz, CDCl3), ꢂC 14.11 and 14.84
We gratefully acknowledge financial support from the
Research Council of Gonbad High Education Center and
great collaboration of Sistan & Baluchestan University and
the University of Western Australia (UWA).
(2OCH2CH3), 44.90 (d, JPC = 228.8 Hz, P+-C-), 55.28 (d,
1
2JPC = 13.5 Hz, P+-C--CH), 59.12 and 61.51 (2OCH2CH3),
3
108.98 and 113.14 (2C, C7H4NO2), 119.93 (d, JPC = 5.3 Hz
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A simple synthesis of stable
Received: May 15, 2010
Revised: July 9, 2010
Accepted: July 12, 2010