Vinyl triphenylphosphonium salt-mediated synthesis of functionalized alkenes

Article abstract of DOI:10.1080/10426500903348047

Deoxybenzoin undergoes a smooth reaction with acetylenic esters in the presence of triphenylphosphine to produce phosphorus ylides. Only the tert-butyl phosphorus ylide undergoes an intramolecular Wittig reaction to produce highly strained cyclobutenes in boiling toluene, which spontaneously undergoes ring-opening reactions to produce highly functionalized 1,3-dienes. The unstable ylides undergo a 1,2-proton transfer and the loss of PPh₃ to produce functionalized alkenes. Copyright

Full text of DOI:10.1080/10426500903348047

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Phosphorus, Sulfur, and Silicon and the
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Vinyl Triphenylphosphonium
Salt–Mediated Synthesis of
Functionalized Alkenes
Sakineh Asghari a , Fahimeh Molaee a & Samaneh Ramezani a
a Department of Chemistry , Mazandaran University , Babolsar, Iran
Published online: 25 Aug 2010.
To cite this article: Sakineh Asghari , Fahimeh Molaee & Samaneh Ramezani (2010) Vinyl
Triphenylphosphonium Salt–Mediated Synthesis of Functionalized Alkenes, Phosphorus, Sulfur, and
Silicon and the Related Elements, 185:9, 1896-1904, DOI: 10.1080/10426500903348047
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Phosphorus, Sulfur, and Silicon, 185:1896–1904, 2010
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500903348047
VINYL TRIPHENYLPHOSPHONIUM SALT–MEDIATED
SYNTHESIS OF FUNCTIONALIZED ALKENES
Sakineh Asghari, Fahimeh Molaee, and Samaneh Ramezani
Department of Chemistry, Mazandaran University, Babolsar, Iran
Deoxybenzoin undergoes a smooth reaction with acetylenic esters in the presence of triph-
enylphosphine to produce phosphorus ylides. Only the tert-butyl phosphorus ylide undergoes
an intramolecular Wittig reaction to produce highly strained cyclobutenes in boiling toluene,
which spontaneously undergoes ring-opening reactions to produce highly functionalized 1,3-
dienes. The unstable ylides undergo a 1,2-proton transfer and the loss of PPh3 to produce
functionalized alkenes.
Keywords Alkyl propiolates; deoxybenzoin; dialkyl acetylenedicarboxylate; triphenylphos-
phine; Wittig reaction
INTRODUCTION
Phosphorus ylides are reactive systems that take part in many valuable reactions in
organic chemistry.1–8 These ylides have found use in a wide variety of reactions interest-
ing to synthesis chemists, especially in the synthesis of naturally occurring products, and
compounds with biological and pharmacological activities.2,9–13 These ylides are usually
prepared by treatment of a phosphonium salt with a base, and the salts are usually prepared
from the phosphine and an alkyl halide.14 Phosphonium salts can also be prepared by
Michael addition of phosphorus (III) compounds such as triphenylphosphine to acetylenic
esters, leading to zwitterionic intermediates, which are not detected even at low temper-
atures. These unstable intermediates can be trapped by a proton donor such as methanol,
amide, imide, strong CH-acid, and a variety of electrophiles to produce various compounds
such as ylides.15
We have recently described the synthesis of 2H-oxetes16 1 from the reaction of
phenacylchloride as an electron-deficient ketone with dialkyl acetylenedicarboxylate and
triphenylphosphine. With the purpose of preparing 2H-oxetes having phenyl and benzyl
group at C-2, such as 2, we performed the reaction of deoxybenzoin 4 with triphenylphos-
phine and dialkyl acetylenedicarboxylates 3. This reaction did not afford the corresponding
2H-oxetes 2, but yielded phosphorus ylide 5 (Scheme 1).
Received 29 June 2009; accepted 18 September 2009.
Address correspondence to Sakineh Asghari, Department of Chemistry, Mazandaran University, P. O. Box.
435, Babolsar, Iran. E-mail: s.asghari@umz.ac.ir
1896

SYNTHESIS OF FUNCTIONALIZED ALKENES
1897
Ph
CH2Ph
Ph
CH2Cl
O
O
RO2C
CO2R
RO2C
CO2R
2
1
Scheme 1
Only compound 5c-I undergoes an intramolecular Wittig reaction to produce highly
strained cyclobutene 6 in boiling toluene, which spontaneously undergoes a ring opening
reaction to produce highly functionalized 1,3-diene 7 (Scheme 2).
O
CH2Cl2
Ph
PPh3
RO2C
C
C
CO2R
+
+
Ph
r.t
R= Me, Et, t-Bu
3
4
O
H
Ph
Ph
Ph
Ph
Toluene
reflux
H
CO2R
O=PPh3
+
Ph3P
RO2C
CO2R
CO2R
6
5
yield of 7(%)
yield of 5(%)
R
CO2R Ph
_
ring-opening
a= Me
70
H
H
b= Et
75
75
_
70
CO2R Ph
c= t-Bu
7
Scheme 2
When the reaction of deoxybenzoin was carried out with alkyl acetylenedicarboxylate
8 (a mono acetylenic ester) in the presence of PPh3, the phosphorus ylide 10 was not
obtained, but the functionalized alkene 9 was isolated (Scheme 3).
RESULTS AND DISCUSSON
On the basis of the chemistry of trivalent phosphorus nucleophiles,1,2,9,13 it is reason-
able to assume that phosphorus ylide 5 results from the initial addition of triphenylphosphine
to dialkyl acetylenedicarboxylate and subsequent protonation of the zwitterionic interme-
diate by the deoxybenzoin. Then the positively charged ion is attacked by the enolate of
deoxybenzoin to form the stable ylides 5a–c. These compounds possess two stereogenic
centers, and two diastereomers are expected (I and II). We could only isolate diastere-
omeric ylides of 5c from its reaction mixture as yellow (5c-I) and white (5c-II) powders,
respectively, but we could not isolate diastereomers of 5a and 5b (Scheme 4).
Both diastereomers of 5c were refluxed separately in toluene. First the diastereomer of
5c (yellow powder) only underwent an intramolecular Wittig reaction to produce unstable

1898
S. ASGHARI ET AL.
O
O
Ph
Ph
RO2C
CH2Cl2
r.t
Ph
PPh3
H
C
CO2R
C
+
+
Ph
H
8
9
H
R
yield of 9
a= Me
b= Et
8
7
Scheme 3
O
O
H
H
Ph
Ph3P
Ph
Ph
Ph
*
*
*
*
H
CO2R
CO2R
Ph3P
H
CO2R
CO2R
Scheme 4
cyclobutene 6, which spontaneously was converted to functionalized 1,3-diene 7 by a
ring-opening reaction.
It seems that when the reaction of deoxybenzoin was carried out with alkyl propiolate
in the presence of PPh3, phosphorus ylide 10 was formed. These ylides are less stable than
5 and spontaneously undergo a 1,2-proton transfer and then loss of triphenylphosphine to
produce functionalized alkenes 11 (Scheme 5).
The structures of 5a–c (I and II) were deduced from 1H, 13C, 31P NMR, IR, and mass
1
spectra. The H NMR spectrum of stable ylide 5c-I (yellow powder, first diastereomer)
exhibited four singlets at about 0.80, 1.26, 1.27, and 1.43 ppm for four tert-butyl groups,
two doublets of doublet at about 3.21 ppm (3JPH 17.8 Hz, 3JHH 11.1 Hz) and 3.20 ppm (3JPH
17.8 Hz, 3JHH 11.1 Hz) for two methine protons of CHCO2But groups, and two doublets
at about 6.55 ppm (3JHH 11.1 Hz) and 6.25 ppm (3JHH 11.1 Hz) for two methine protons
of CHPh groups with unequal intensity ratio for their (Z) and (E) isomers, respectively.
As the temperature was increased, these signals collapsed; for example, two doublets at
about 6.25 and 6.55 ppm for CHPh converted to a broad doublet at 333 K. This observation
is attributed to the temperature-dependent equilibrium between the geometric (rotational)
isomers, E and Z, i.e., the result of a restricted rotation (Scheme 6).
The 13C NMR spectrum of 5c-I displayed two unequal doublets at about 39.66 ppm
(1JPC 123.8 Hz) and 42.63 ppm (1JPC 131.9 Hz) for two P C groups, two unequal doublets
at about 48.13 ppm (2JPC 12.9 Hz) and 47.58 ppm (2JPC 12. Hz) for two CHCO2But groups,
and two unequal doublets at about 51.38 ppm (3JPC 4.9 Hz) and 52.66 ppm (3JPC 5.4 Hz)
for two CHPh groups, respectively. The 31P NMR spectrum of 5c-I exhibited two unequal
signals at about 23.72 and 24.51 ppm for their Z- and E-isomers.

SYNTHESIS OF FUNCTIONALIZED ALKENES
1899
O
H
..
Ph3P
H
CO2R
H
Ph
H
CH2Cl2
r.t
Ph
H
CO2R
_
C
C
_
+
+
Ph3P
O
+
O
H
Ph3P
Ph
CO2R
1,2- proton transfer
Ph
Ph
H
+
+
Ph
_
Ph3P
CO2R
H
H
H
10
O
O
Ph
H
Ph
Ph
RO2C
Ph
-PPh3
_
Ph3+P
CO2R
H
H
H
11
Scheme 5
O
O
H
CO2R
H
CO2R
_
Ph
Ph
OR
O
H
Ph
_
O
+
H
+
Ph3P
Ph3P
OR
Z-isomer
E-isomer
Scheme 6
The 1H NMR spectrum of 5c-II (white powder, second diastereomer) exhibited four
singlets at about 0.92, 1.30, 1.31, and 1.60 ppm for four tert-butyl groups, two doublet of
3
doublets at about 3.35 ppm (3JPH 18.4 Hz, JHH 10.8 Hz) and 3.36 ppm (3JPH 18.3 Hz,
3JHH 10.7 Hz) for two methine protons of CHCO2But groups, and two doublets at about
6.32 ppm (3JHH 10.7 Hz) and 5.98 ppm (3JHH 10.8 Hz) for two methine protons of CHPh
groups with unequal intensities, respectively. The 13C NMR spectra of 5c-II displayed
two unequal doublets at about 38.66 ppm (1JPC 126.6 Hz) and 41.12 ppm (1JPC 133.7
Hz) for two P C groups, two unequal doublets at about 47.86 ppm (2JPC 12.9 Hz) and
47.12 ppm (2JPC 12.4 Hz) for two CHCO2But groups, and two unequal doublets at about
51.86 ppm (3JPC 4.9 Hz) and 52.80 ppm (3JPC 5.5 Hz) for two CHPh groups, for their Z-
and E-isomers, respectively. The 31P NMR spectrum of 5c-II exhibited two unequal signals
at 23.72 and 24.10 ppm. The mass spectrum of 5c displayed a molecular ion peak at m/z
684. Fragmentations involve the loss of one of the side chains (C4H7, OC4H7, CO2But,
1
and PPh3). The structural assignment made on the basis of H and 13C NMR spectra for
compound 5c was supported by a measurement of its IR spectrum.
1
The H and 13C NMR spectra of the mixture of diastereomeric ylides 5a and 5b
are similar to those of 5c, except for the esteric groups, which exhibited characteristic

1900
S. ASGHARI ET AL.
resonances with appropriate chemical shifts. The mass spectra of 5a and 5b exhibited
molecular ion peaks at m/z 600 and 628 for methyl and ethyl derivatives, respectively.
1
Selected H, 13C, and 31P NMR chemical shifts and coupling constants in diastere-
omeric ylides 5a–c are shown in Table I. Partial assignments of IR and mass spectra are
given in the Experimental section.
The structure of 7 was deduced from its 1H, 13C NMR, IR, and mass spectra. The 1H
NMR of 7 exhibited two singlets at about 1.45 and 1.65 ppm for two tert-butyl groups, and
two singlets at about 5.40 and 6.92 ppm for two olefinic protons. The 13C NMR spectrum
of 7 displayed two signals at about 28.10 and 28.15 ppm for two tert-butyl groups, two
signals at about 80.70 and 82.56 ppm for two quaternary carbons of tert-butoxy groups,
and two signals at about 120.68 and 151.19 ppm for olefinic carbons. The mass spectrum
of 7 displayed a molecular ion peak at m/z 406. Fragmentations involve the loss of one of
the side chains. The structure of 7 was supported by measurements of its IR spectrum. 1H,
13C NMR, IR, and mass spectra of 7 are given in the Experimental section.
The structures of 11a and 11b were deduced from their 1H, 13C NMR, IR, and mass
spectra. The 1H NMR spectrum of 11a exhibited a signal at about 3.75 ppm for methoxy
group, a singlet at about 5.30 ppm for methine proton of CHPh group, and two signals
at about 5.89 and 6.48 ppm for two geminal vinylic protons. The 13C NMR spectrum of
11a displayed a signal at about 52.2 ppm for methoxy group, a signal at 55.39 ppm for
CHPh, and two signals at 132.96 and 140.23 ppm for olefinic carbons. The mass spectrum
of 11a exhibited a molecular ion peak at m/z 280. The IR spectrum of 11a displayed strong
carbonyl absorption bands at 1709 and the C C absorption band at 1636 cm−1. The 1H and
13C NMR spectra of 11b are similar to those of 11a, except for the esteric group, which
exhibited characteristic resonances with appropriate chemical shifts. The mass spectrum of
11b exhibited a molecular ion peak at m/z 294.
In conclusion, the present method may be considered as a practical synthesis of stable
diastereomeric phosphorus ylides, which can be converted to functionalized alkenes under
neutral conditions in good yields.
EXPERIMENTAL
Deoxybenzoin, triphenylphosphine, dialkyl acetylenedicarboxylates, and alkyl pro-
piolate were obtained from Fluka (Buche, Switzerland) and were used without further
purification. IR spectra were recorded on a FT-IR Bruker Vector 22 spectrometer. Mass
spectra were recorded on a Finnigan-Matt 8430 mass spectrometer operating at an ionization
potential of 70 eV. 1H, 13C, and 31P NMR spectra were measured with a Bruker DRX-300
AVANCE spectrometer at 300.1, 75.5, and 121.5 MHz, respectively. Melting points were
measured on an Electrothermal 9100 apparatus. Elemental analyses were performed using
a Heraeus CHN-O rapid analyzer.
Preparation of Dialkyl 2-(2-Oxo-1,2-diphenyl
ethyl)-3-(triphenylphosphoran yliden)succinate (5): General Procedure
A solution of dialkyl acetylenedicarboxylate (2 mmol) in CH2Cl2 (3 mL) was added
dropwise to a magnetically stirred solution of deoxybenzoin (0.39 g, 2 mmol) and triph-
enylphosphine (0.52 g, 2 mmol) in CH2Cl2 (10 mL) at −10◦C over 10 min. The mixture
was allowed to stand at room temperature for 24 h. The solvent was removed under re-
duced pressure, and the residue was purified by silica gel (Merck silica gel, 230–400 mesh)

SYNTHESIS OF FUNCTIONALIZED ALKENES
1901
Table I Selected 1H, 13C, and 31P NMR chemical shifts (δ in ppm) and coupling constants (J in Hz) for ylides
5a–c
Ylides 5
1H, 13C, and 31P NMR: δ (ppm) (CDCl3, TMS)
5a-I (Z-isomer)
δH: 2.89 and 3.46 (2OCH3), 3.35 (1H, dd, 3JPH 17.3 Hz, 3JHH 11.1 Hz, CH), 6.42 (1H, d,
3JHH 11.1 Hz, CH)
δC: 40.91 (d, 1JPC 124.6 Hz, P C), 47.60 (d, 2JPC 12.5 Hz, CH), 48.46 and 51.44
(2OCH3), 51.88 (d, 3JPC 5.0 Hz, CH), 201.08 (C O, Ketone)
δp: 23.63
(E-isomer)
δH: 3.46 and 3.56 (2OCH3), 3.33 (1H, dd, 3JPH 17.1 Hz, 3JHH 11.1 Hz, CH), 6.22 (1H, d,
3JHH 11.1 Hz, CH)
δC: 41.88 (d, 1JPC 133.4 Hz, P C), 46.96 (d, 2JPC 12.6 Hz, CH), 49.85 and 50.06
(2OCH3), 52.25 (d, 3JPC 5.2 Hz, CH), 200.62 (C O, Ketone)
δp: 24.16
5a-II (Z-isomer)
(E-isomer)
δH: 3.01 and 3.55 (2OCH3), 3.5 (1H, dd, 3JPH 17.0 Hz, 3JHH 10.7 Hz, CH), 6.27 (1H, d,
3JHH 10.7 Hz, CH)
δC: 39.37 (d, 1JPC 126.1 Hz, P C), 47.26 (d, 2JPC 12.5 Hz, CH), 48.61 and 51.46
(2OCH3), 51.77 (d, 3JPC 4.9 Hz, CH), 201.08 (C O, Ketone)
δp: 24.22
δH: 3.44 and 3.74 (2OCH3), 3.61 (1H, dd, 3JPH 18.6 Hz, 3JHH 10.6 Hz, CH), 5.81 (1H, d,
3JHH 10.6 Hz, CH)
δC: 40.16 (d, 1JPC 133.5 Hz, P C), 46.29 (d, 2JPC 12.4 Hz, CH),50.91 and 51.00
(2OCH3), 53.52 (d, 3JPC 5.5 Hz, CH), 201.45 (C O, Ketone)
δp: 24.59
5b-I (Z-isomer)
(E-isomer)
δH: 0.30 (3H, t, 3JHH 7.1 Hz, CH3), 0.99 (3H, t, 3JHH 7.1 Hz, CH3), 3.33 (1H, dd, 3JHP 16.9
Hz, 3JHH 11.1 Hz, CH), 3.43–4.20 (4H, m, 2OCH2), 6.47 (1H, d, 3JHH 11.1 Hz, CH)
δC: 13.95 and 13.98 (2CH3), 40.68 (d, 1JPC 124.5 Hz, P C), 47.36 (d, 2JPC 12.5 Hz, CH),
51.75 (d, 3JPC 4.5 Hz, CH), 57.06 and 59.86 (2OCH2), 201.79 (C O Ketone)
δp: 24.09
δH: 1.23 (3H, t, 3JHH 7.0 Hz, CH3), 1.38 (3H, t, 3JHH 7.1 Hz, CH3), 3.29 (1H, dd, 3JHP
16.9 Hz, 3JHH 11.1 Hz, CH), 3.43–4.20 (4H, m, 2OCH2), 6.24 (1H, d, 3JHH 11 Hz, CH)
δC: 15.15 and 15.48 (2CH3), 42.14 (d, 1JPC 127.6 Hz, P C), 46.75 (d, 2JPC 12.5 Hz, CH),
52.71 (d, 3JPC 4.5 Hz, CH), 58.03 and 59.86 (2OCH2), 200.67 (C O Ketone)
δp: 24.24
δH: 0.37 (3H, t, 3JHH 7.1 Hz, CH3), 1.22 (3H, t, 3JHH 7.0 Hz, CH3), 3.36 (1H, dd, 3JHP
16.5 Hz, 3JHH 10.7 Hz, CH), 3.43–4.20 (4H, m, 2OCH2), 6.32 (1H, d, 3JHH 10.7 Hz,
CH)
δC: 13.95 and 13.98 (2CH3), 39.22 (d, 1JPC 126.3 Hz, P C), 47.49 (d, 2JPC 12.0 Hz, CH),
51.59 (d, 3JPC 4.8 Hz, CH), 57.15 and 60.46(2OCH2), 201.07 (C O Ketone)
δp: 24.06
5b-II (Z-isomer)
(E-isomer)
δH: 1.01 (3H, t, 3JHH 7.0 Hz, CH3), 1.08 (3H, t, 3JHH 7.1 Hz, CH3), 3.43 (1H, dd, 3JHP 16.5
Hz, 3JHH 10.7 Hz, CH), 3.43–4.20 (4H, m, 2OCH2), 5.91 (1H, d, 3JHH 10.7 Hz, CH)
δC: 14.09 and 14.16 (2CH3), 40.35 (d, 1JPC 127.1 Hz, P C), 47.11 (d, 2JPC 12 Hz, CH),
53.26 (d, 3JPC 4.9 Hz, CH), 58.03 and 60.46 (2OCH2), 200.76 (C O Ketone)
δp: 23.54
5c-I (Z-isomer)
(E-isomer)
δH: 0.80 and 1.27 (18H, 2s, 2CMe3), 3.21 (1H, dd, 3JPH 17.8 Hz, 3JHH 11.1 Hz, CH), 6.55
(1H, d, 3JHH 11.1 Hz, CH)
δC: 28.02 and 28.20 (2CMe3), 39.69 (d, 1JPC 123.8 Hz, P C), 48.13 (d, 2JPC 12.9 Hz,
CH), 51.38 (d, 3JPC 4.9 Hz, CH), 76.54 and 79.18 (2CMe3), 202.54 (C O Ketone)
δp: 23.72
δH: 1.26 and 1.43 (18H, 2s, 2CMe3), 3.20 (1H, dd, 3JPH 17.8 Hz, 3JHH 11.1 Hz, CH), 6.25
(1H, d, 3JHH 11.2 Hz, CH)
δC: 28.02 and 28.96 (2CMe3), 42.63 (d, 1JPC 131.9 Hz, P C), 47.58 (d, 2JPC 12.7 Hz,
CH), 52.66 (d, 3JPC 5.4 Hz, CH), 77.02 and 77.04 (2CMe3), 201.24 (C O Ketone)
δp:24.51
(Continued on next page)

1902
S. ASGHARI ET AL.
Table I Selected 1H, 13C, and 31P NMR chemical shifts (δ in ppm) and coupling constants (J in Hz) for ylides
5a–c (Continued)
Ylides 5
1H, 13C, and 31P NMR: δ (ppm) (CDCl3, TMS)
5c-II (Z-isomer)
δH: 0.92 and 1.30 (18H, 2s, 2CMe3), 3.35 (1H, dd, 3JPH 18.4 Hz, 3JHH 10.8 Hz, CH),
6.32 (1H, d, 3JHH 10.6 Hz, CH)
δC: 28.06 and 28.29 (2CMe3), 38.66 (d, 1JPC 126.6 Hz, P C), 47.86 (d, 2JPC 12.9 Hz,
CH), 51.86 (d, 3JPC 4.9 Hz, CH), 76.40 and 79.72 (2CMe3), 200.86 (C O Ketone)
δp: 23.72
(E-isomer)
δH: 1.31 and 1.60 (18H, 2s, 2CMe3), 3.36 (1H, dd, 3JPH 18.3 Hz, 3JHH 10.7 Hz, CH),
5.98 (1H, d, 3JHH 10.8 Hz, CH)
δC: 28.06 and 28.96 (2CMe3), 41.12 (d, 1JPC 133.7 Hz, P C), 47.12 (d, 2JPC 12.4 Hz,
CH), 52.80 (d, 3JPC 5.51 Hz, CH), 76.81 and 76.84 (2CMe3), 200.72 (C O Ketone)
δp:24.10
column chromatography using hexane:ethyl acetate (50:50) as an eluent. A mixture of two
diastereomeric ylides was obtained for 5a and 5b, but for 5c, ylides 5c-I and 5c-II were
isolated as yellow and white powders, respectively.
Dimethyl 2-(2-oxo-1,2-diphenyl ethyl)-3-(triphenylphosphoran yliden)
succinate (5a, C38H33O5P). Mixture of diastereomeric ylide 5a, yield 70%, IR (KBr)
(νmax, cm−1): 1729, 1684 (C O) and 1633 (C C); MS, m/z (%): 600 (M+) (4), 541 (8),
509 (5), 405 (100), 278 (30), 262 (53), 105 (82), 77 (60).
Diethyl 2-(2-oxo-1,2-diphenyl ethyl)-3-(triphenylphosphoran yliden)
succinate (5b, C40H37O5P). Mixture of diastereomeric ylides of 5b, yield 75%, IR
(KBr) (υmax, cm−1): 1724, 1679 (C O), 1628 (C C); MS, m/z (%): 628 (M+) (3) 583 (5),
555 (18), 509 (22), 433 (100), 278 (15), 262 (93), 183 (87), 105 (78), 77 (45).
Di-tert-butyl 2-(2-oxo-1,2-diphenylethyl)-3-(triphenylphosphoran yliden)
succinate (5c, C44H45O5P). First diastereomer: 5c-I, yellow powder, mp 155–157◦C,
yield 45%; IR (KBr) (υmax, cm−1): 1729 and 1710 (C O), 1678 (C C); MS, m/z (%): 684
(M+) (5), 583 (23), 489 (81), 377 (100), 333 (48), 278 (30), 262 (25), 77 (40), 57 (60).
Second diastereomer: 5c-II, white powder, mp 208–210◦C, yield 55%; IR (KBr)
(υmax, cm−1): 1725 and 1710 (C O), 1678 (C C); MS, m/z (%): 684 (M+) (3), 526 (36),
489 (65), 377 (100), 333 (48), 278 (20), 262 (37), 57 (65).
Preparation of Di(tert–butyl) (E-2-[(Z)-1,2-Diphenyl-1-ethenyl]2-
butenedioate (7, C26H30O4)
Compound 5c-I was refluxed in toluene, and after 24 h, it was converted to compound
7 by loss of OPPh3. The solvent was removed under reduced pressure, and viscous residue
was purified by silica gel (Merck silica gel, 230–400 mesh) column chromatography using
hexane:ethyl acetate (50:50). The solvent was removed under reduced pressure, and the
product was obtained from recrystallization in ether.
7, white powder, mp 114–116◦C, yield 70%; IR (KBr) (υmax, cm−1): 1720 and 1685
(C O) and 1610 (C C); MS, m/z (%): 406 (M+) (2), 350 (4), 294 (83), 276 (62), 231
1
(100), 203 (34), 105 (20), 77 (6), 57 (63); H NMR (300 MHz, CDCl3): δH 1.45 (9H, s,
CMe3), 1.65 (9H, s, CMe3), 5.40 (1H, s, olefinic proton), 6.92 (1H, s, olefinic proton),
6.85–6.89 (2H, m, aromatic protons), 7.07–7.14 (3H, m, aromatic protons), 7.20–7.23 (2H,

SYNTHESIS OF FUNCTIONALIZED ALKENES
1903
m, aromatic protons), 7.38–7.44 (3H, m, aromatic protons);13C NMR (75.5 MHz, CDCl3):
δC 28.10 (2CMe3), 80.70 and 82.56 (2OCMe3), 120.68, 151.19 (olefinic carbons), 128.08,
129.13, 129.94, 130.12, 134.84, 135.72, 136.92 and 137.70 (aromatic carbons), 164.62 and
167.27 (2C O, ester).
Preparation of Methyl-2-[2-oxo-1,2-diphenyl ethyl)acrylate
(11a, C18H16O3)
A solution of triphenylphosphine (0.52 g, 2 mmol) in CH2Cl2 (3 mL) was added
dropwise to a magnetically stirred solution of deoxybenzoin (0.39 g, 2 mmol) and methyl
propiolate (0.17 mL, 2 mmol) in CH2Cl2 (10 mL) at −10◦C over 10 min. The reaction
mixture then was allowed to warm up at room temperature and was stirred for 24 h.
The solution was removed under reduced pressure, and the residue was purified by silica
gel (Merck silica gel, 230–400 mesh) column chromatography using hexane:ethyl acetate
(80:20) as an eluent. The solvent was removed under reduced pressure, and 11a was
obtained as yellow powder.
Yellow powder, mp 62–64◦C, yield 80%; IR (KBr) (υmax, cm−1): 1709 (C O), 1636
1
(C C); MS, m/z (%): 280 (M+) (5), 249 (5), 115 (41),105 (PhCO+) (100), 77 (79); H
NMR (300 MHz, CDCl3): δH 3.75 (3H, s, OCH3), 5.30 (1H, s, CH), 5.89 (1H, s, CH),
6.48 (1H, s, CH), 7.26–8.00 (10H, m, aromatic protons); 13C NMR (75.5 MHz, CDCl3):
δC 52.20 (OCH3), 55.39 (CH), 127.72, 128.55, 128.69, 128.90, 129.12, 129.58, 135.67
and 136.35 (aromatic carbons), 132.96 and 140.23 (olefinic carbons), 167.07 (C O ester),
197.48 (C O ketone).
Ethyl-2-[2-oxo-1,2-diphenyl ethyl)acrylate (11b, C19H18O3)
White powder, mp 52–54◦C, yield 70%; IR (KBr) (υmax, cm−1): 1712 and 1704
(C O), 1645 (C C); MS, m/z (%): 294 (M+) (4), 249 (8), 115 (37), 105 (100), 77 (85);
1H NMR (300 MHz, CDCl3): δH 1.23 (3H, t, 3JHH 7.1 Hz CH3), 4.16–4.24 (2H, m, OCH2),
5.27 (1H, s, CH), 5.89 (1H, s, CH), 6.49 (1H, s, CH), 7.27–7.98 (8H, m, Ph), 7.98–8.00
(2H, m, Ph); 13C NMR (75.5 MHz, CDCl3): δC 14.06 (CH3), 55.37 (CH), 61.16 (OCH2),
127.70, 128.44, 128.54, 128.88, 129.11, 129.60, 135.67 and 136.39 (aromatic carbons),
132.95 and 140.59 (olefinic carbons), 166.54 (C O ester), 197.53 (C O ketone).
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