Synthesis and NMR study of α-keto stabilized ylides of the type RCOCH=PAr3, (R=MeO-C6H4, Cl-C6H 4, NO2-C6H4, α-thiophenyl and naphthyl; Ar = p-tolyl or phenyl)

Article abstract of DOI:10.1002/jccs.200800029

Synthesis and characterization of five new phosphonium salts and related phosphorus ylides of the type R-COCH=PAr₃ are reported. The reaction of bromo 4′-methoxo/chloro/nitro acetophenone, α-thiophenyl and naphthoyl acetophenone with triphenylp

Full text of DOI:10.1002/jccs.200800029

Journal of the Chinese Chemical Society, 2008, 55, 197-200
197
Synthesis and NMR Study of a-Keto Stabilized Ylides of the Type
RCOCH=PAr3, (R=MeO-C6H4, Cl-C6H4, NO2-C6H4, a-Thiophenyl and
Naphthyl; Ar = p-Tolyl or Phenyl)
Seyyed Javad Sabounchei,* Hassan Nemattalab and Vida Jodaian
Faculty of Chemistry, Bu–Ali Sina University, Hamedan, 65174, Iran
Synthesis and characterization of five new phosphonium salts and related phosphorus ylides of the
type R-COCH=PAr3 are reported. The reaction of bromo 4¢-methoxo/chloro/nitro acetophenone, a-thio-
phenyl and naphthoyl acetophenone with triphenylphosphine or triparatolylphosphine in acetone gives
phosphonium salts. Dehydrogenation of these salts in aqueous sodium hydroxide solution form ylides.
Characterization of obtained compounds was performed by IR, 1H, 13C,31P NMR and elemental analysis.
Keywords: Triphenylphosphine; Triparatolylphosphine; Carbonyl stabilized phosphorus ylide
and phosphonium salt.
INTRODUCTION
Phosphorus ylides are important reagents in organic
its related compounds (Table 1). These ylides are obtained
from initial reaction of bromo a-ketone (1) and phosphine
(2) to formation of phosphonium salt (3) and concomitant
deprotonation of 3 in aqueous sodium hydroxide solution
(Scheme I). Physical data and elemental analysis of the
compounds 3a-e and 4a-e are listed in Table 1.
chemistry, especially in the synthesis of naturally occurring
products with biological and pharmacological activities.1
Since its development the Wittig reaction has remained one
of the primary routes utilized in synthetic organic chemis-
try for the construction of carbon-carbon double bonds.2
The Wittig reagent, or ylide, necessary for the reaction is
produced by deprotonation of the corresponding phospho-
nium salt generated by the quaternization of a phosphine
with an organic halide.3 In recent years there have been var-
ious developments in ylide synthesis.4-6 We are currently
interested in synthesis and characterization of such ylides
as keto-stabilized phosphorus ylides.7
Infrared spectra
Carbonyl stabilized ylides of these types exhibit in-
teresting properties such as high stability and ambidentate
character as ligands that can be rationalized in terms of the
resonance forms A-C (where C is presented by the geomet-
rical isomers) (Scheme II).8
Selected IR data are listed in Table 2. The n CO for
ylides are observed in lower frequencies than those of the
related salts as in the case of other resonance stabilized
ylides,9 suggesting some removal of electron density in the
RESULTS AND DISCUSSION
C=O bond. The n (P+ C-) which is also diagnostic for ylides
-
occurs at higher frequencies than those of the related
salts.10
In this work, we describe the preparation and charac-
terization of five new ylides of the type R-COCH=PAr3 and
Scheme I
* Corresponding author. E-mail: jsabounchei@yahoo.co.uk

198 J. Chin. Chem. Soc., Vol. 55, No. 1, 2008
Sabounchei et al.
Table 1. Physical data and elemental analyses for phosphonium salts and phosphoranes
Compound
R
Ar
M.p. °C
Yield %
C (%)
H (%)
N (%)
3a
4a
3b
4b
3c
4c
3d
4d
3e
4e
OMe
OMe
p-tolyl
p-tolyl
p-tolyl
p-tolyl
p-tolyl
p-tolyl
Ph
206-208
171-172
253-255
160-162
212-213
156-158
242-243
221-222
248-249
193-194
73
80
92
82
88
85
85
78
93
84
67.25 (67.55) 5.62 (5.67)
79.83 (79.62) 6.77 (6.46)
64.86 (64.76) 5.16 (5.06)
76.29 (76.23) 5.96 (5.74)
-
-
-
-
Cl
Cl
NO2
63.59 (63.51) 4.90 (4.96) 2.80 (2.55)
74.21 (74.51) 6.03 (5.61) 3.33 (3.00)
NO2
a-thiophenyl
a-thiophenyl
Naphthoyl
Naphthoyl
62.99 (61.67) 4.36 (4.28)
75.14 (74.61) 4.9 (4.92)
-
-
-
-
Ph
Ph
69.96 (70.45) 4.62 (4.69)
83.49 (83.72) 5.27 (5.35)
Ph
Scheme II
Table 2. n CO and n P-C of selected phosphonium salts and
phosphoranes (cm-1)
Table 3. 1H NMR data for phosphonium salts and phosphoranes
(CDCl3 as solvent and J in Hertz)
Compound
P-C CO Reference
Compound CH/CH2
2JPH
5.95 (d) 12.20
5.68 (b)
CH3 OCH3
Arom.
3a
993 1649
878 1583
984 1672
882 1581
996 1683
886 1600
995 1637
879 1527
993 1660
873 1523
3a
4a
3b
4b
3c
4c
3d
4d
3e
4e
2.51
2.22
2.45
2.39
2.46
2.41
-
3.82 6.94-8.33 (m)
3.58 6.67-8.07 (m)
4a
-
3b
6.14 (d) 12.10
4.34 (d) 23.12
6.35 (d) 12.30
4.47 (d) 22.67
6.11 (d) 12.72
4.32 (d) 23.12
6.28 (d) 12.20
4.58 (d) 06.35
-
-
-
-
-
-
-
-
7.25-8.41 (m)
7.20-7.95 (m)
7.28-8.70 (m)
7.26-8.14 (m)
7.53-8.14 (m)
7.01-7.70 (m)
7.53-8.28 (m)
7.52-8.49 (m)
4b
3c
4c
3d
4d
-
3e
-
4e
-
Ph3PCHCOPh (BPPY)
(C6H5)3P+-CH2COPh
887 1525
998
10, 8
10
11
d, doublet; b, broad; m, multiplet.
-
(C6H4CH3)3PCHCOOCH2C6H5 (BTPY) 811 1615
(p-tolyl)3P+-C-H2COOCH2C6H5
(C6H5)3PCHCOC6H4OCH3
Ph3PCHCON(CH3)2
851
-
11
Table 4. 31P NMR data for phosphonium salts and
phosphoranes (CDCl3 as solvent)
878 1601
12
9
-
-
1530
1530
Ph3PCHCOCH3 (APPY)
13
Compound
a
b
c
d
e
3
4
18.45
12.92
18.11
13.15
17.69
13.13
18.83
13.84
19.30
14.12
NMR spectra
The1H NMR data of the ylides along with those of the
parent phosphonium salts are listed in Table 3. The CH sig-
nals of the ylides are shifted up field compared to those of
the phosphonium salts due to the increasing of the electron
density in the P-C bonds and this interpretation holds to ex-
plain the increasing of 2JPH.
nals in 31P NMR (Table 4). The appearance of single signals
in the 31P NMR spectra indicates the presence of only one
type of molecule for all structures.
The 13C NMR data of the salts and phosphoranes are
listed in Tables 5 and 6. A low field shift for CH signal to-
gether with increasing of related coupling constants is ob-
Up field shifting is also observed for phosphorus sig-

Multinuclear NMR Study on a-Phosphorus Ylides
J. Chin. Chem. Soc., Vol. 55, No. 1, 2008 199
Table 5. 13C NMR data for phosphonium salts (CDCl3 as solvent and J in Hertz)
Possible
3a
3b
3c
3d
35.37
3e
Assignments
CH2
1J(p-c)
36.62 (d)
62.31
36.84 (d)
62.11
37.54 (d)
60.74
36.61 (d)
67.9
60.17
141.69 (d)
7.91
(COPh) (i)
2J(p-c)
133.2 (d)
11.42
139.37
-
138.74 (d)
5.72
134.81
-
**
(COPh) (o)
(COPh) (m)
(COPh) (p)
CH3
141.85
112.88
144.67
20.74
144.49
127.61
144.37
20.48
144.72
122.43
149.41
20.62
*
*
**
**
*
-
-
CH3O
P.Ar3 (i)
1J(p-c)
55.23
127.56 (d)
95.94
-
-
-
-
114.26 (d)
92.00
114.27 (d)
91.91
126.42 (d)
91.24
133.59 (d)
10.70
128.53 (d)
12.16
129.81
184.53 (d)
6.44
124.26 (d)
91.21
132.78 (d)
10.29
128.93 (d)
13.02
131.11
190.82 (d)
5.81
P.Ar3 (o)
2J(p-c)
131.18 (d)
10.70
132.56 (d)
10.72
132.80 (d)
11.13
P.Ar3 (m)
3J(p-c)
128.53 (d)
12.55
129.47 (d)
13.29
129.68 (d)
13.67
P.Ar3 (p)
CO
2J(p-c)
130.19
195.41 (d)
6.02
130.12
189.72 (d)
8.95
129.98
190.23 (d)
5.97
d = double, i = ipso, o = ortho, m = meta, p = para.
* 137.54, 128.98 and 124.49 (thiophene).
** 119.59 and 115.63 (naphthyl).
Table 6. 13C NMR data for phosphoranes (CDCl3 as solvent and J in Hertz)
Possible
4a
4b
4c
4d
4e
Assignments
CH
1J(p-c)
50.89 (d)
112.2
51.19 (d)
112
54.13 (d)
113.47
147.21
1.58
49.83 (d)
112.77
148.32
18.06
*
50.77 (d)
108.92
138.2
14.01
**
(COPh) (i)
2J(p-c)
163.59
-
139.71 (d)
14.91
(COPh) (o)
4J(p-c)
144.63 (d)
2.64
142.00 (d)
2.84
142.66
2.57
-
-
**
(COPh) (m)
(COPh) (p)
CH3
113.11
127.98
20.83
127.12
134.27
20.95
122.72
147.87
21.325
-
*
*
**
-
-
CH3O
P.Ar3 (i)
1J(p-c)
54.76
115.28 (d)
97.84
-
-
-
123.33 (d)
93.56
122.98 (d)
93.63
132.84 (d)
10.52
129.52 (d)
12.64
127.55
-
126.42 (d)
91.24
132.70 (d)
10.36
128.53 (d)
12.16
131.81 (d)
2.75
126.76 (d)
92.27
132.95 (d)
10.41
128.72 (d)
12.34
131.98 (d)
1.98
P.Ar3 (o)
2J(p-c)
132.89 (d)
10.99
132.53 (d)
10.50
P.Ar3 (m)
3J(p-c)
129.81 (d)
13.33
129.10 (d)
12.66
P.Ar3 (p)
4J(p-c)
CO
2J(p-c)
131.27
-
127.88
-
188.86 (d)
3.21
182.31 (d)
3.58
181.15
-
177.72 (d)
3.71
184.61 (d)
-
d = double, m = multiplet, i = ipso, o = ortho, m = meta, p = para.
* 126.72 and 125.63 (thiophene).
** 124.49-127.26 (m, naphthyl).
served for ylides, suggesting low shielding of carbon atoms
(replacing of CH2 group with CH group) but increasing
electron density in the P-C bond. An up field shift for CO
signals is also observed for all ylides that is due to the in-

200 J. Chin. Chem. Soc., Vol. 55, No. 1, 2008
Sabounchei et al.
creasing of electron density on the carbon atom (Scheme
II).
24 h. The white precipitate of 4¢-methoxobenzoylmethyl-
enetriparatolylphosphorane was obtained. The product was
washed several times with distilled water and air dried.
EXPERIMENTAL SECTION
Received April 30, 2007.
Physical measurements: Melting points were mea-
sured on an SMPI apparatus. Elemental analysis for C, H
and N were performed using a PE 2400 series II analyzer.
IR spectra were recorded on a Shimadzu 435-U-04 FT
spectrophotometer (KBr pellets). NMR spectra were ob-
tained using a 90 MHz Jeol FT-NMR spectrometer with
field strength of 2.1 Tesla.
REFERENCES
1. Wittig, G. Science 1980, 210, 600.
2. Maryanoff, B. E.; Reitz, A. B. Chem Rew. 1989, 89, 863.
3. Johonson, A. W.; Kasaka, W. C.; Starnewski, K. A. O.;
Dixon, D. A. Ylides and Imines of Phosphorus; Wiley: New
York, 1993; pp 101-127.
4. Yavari, I.; Ramazani, A. Synth. Commun. 1996, 26, 4495.
5. Yavari, I.; Ramazani, A. Phosphorus, Sulfur Silicon Relat.
Elem. 1997, 130, 73.
Synthesis of [(p-tolyle)3PCH2COC6H4-OMe]Br, (gen-
eral procedure)
To a solution of 2-bromo 4¢-methoxoacetophenone
(0.227 g, 1 mmol), in acetone (10 mL) was added a solution
of triparatolylphosphine (0.304 g, 1 mmol) in the same sol-
vent (5 mL). The colorless solution was stirred at room
temperature for 4 h. The suspension was concentrated un-
der reduced pressure to 3 mL. After addition of diethylether
the precipitate was filtered off, washed with diethyl ether (2
× 10 mL) and dried under reduced pressure.
6. Ramazani, A.; Bodaghi, A. Tetrahedron Lett. 2000, 41, 567.
7. Sabounchei, S. J.; Karami, K. Phosphorus, Sulfur Silicon
Relat. Elem. 2003, 178, 1559.
8. Ramirez, F.; Dershowitz, S. J. Org. Chem. 1975, 22, 41.
9. Vicente, J.; Chicote, M. T.; Lagunas, M. C.; Jones, P. G. J.
Chem. Soc. Dalton Trans. 1991, 2579.
10. Bravo, P.; Fronza, G.; Ticozzi, C. J. Organomet. Chem.
1976, 111, 361.
11. Sabounchei, S. J.; Dadrass, A. R.; Jafarzadeh, M.; Khavasi,
H. R. J. Organomet. Chem. 2007, 692, 2500.
12. Sabounchei, S. J.; Jodaian, V.; Khavasi, H. R. Polyhadron
2007, 26, 2845.
Synthesis of (p-tolyle)3PCHCOC6H4-OMe, (general
procedure)
To an aqueous solution of NaOH (0.5 m, 50 mL), was
added (0.532 g, 1 mmol) of 4¢-methoxobenzoylmethylene-
triparatolylphosphoniom salt (3a) and stirred at 50 ºC for
13. Onishi, M.; Ohama, Y.; Hiraki, K.; Shintan, H. Polyhedron.
1982, 1, 539.