Synthesis of α-phosphonylated phosphonium and sulfonium ylides: Study of Their Thermal behavior

Article abstract of DOI:10.1002/hc.20530

The additions of two equivalents of trialkylphosphites onto phosphonodithioformates produce stabilized α-sulfanyl-α- phosphonylphosphonium ylides. Their subsequent reaction with alkyl or benzyl halides gives stabilized sulfonium ylides. Thermal treatment

Full text of DOI:10.1002/hc.20530

Heteroatom Chemistry
Volume 20, Number 3, 2009
Synthesis of α-Phosphonylated Phosphonium
and Sulfonium Ylides: Study of Their
Thermal Behavior
Aboubacary Sene,1 Serge Masson,2 and Michel Vazeux2
1LCPN, Universite´ Cheikh Anta Diop Dakar-Fann, Se´ne´gal
2Laboratoire de Chimie Mole´culaire et Thio-organique (LCMT), ENSICAEN-Universite´ de Caen
Basse-Normandie, CNRS, 6 Bd. Mare´chal Juin, 14050, France
Received 8 October 2008
of amines, and cycloaddition reactions [1a,2]. The
ABSTRACT: The additions of two equivalents of
addition of dialkyl and trialkylphosphites to phos-
trialkylphosphites onto phosphonodithioformates
phonodithioformates has been previously examined
produce stabilized α-sulfanyl-α-phosphonyl phospho-
in our group [3] and is shown to be a convenient
nium ylides. Their subsequent reaction with alkyl or
method to access methylene bis-phosphonate
benzyl halides gives stabilized sulfonium ylides. Ther-
derivatives [3b,e]. Moreover, because of their hy-
mal treatment of these phosphonium and sulfonium
drolytic stability and their remarkable chelating
ylides leads to α-sulfanyl methylene bis-phosphonates
features, they have been recognized as biologically
through protonation–dealkylation intramolecular re-
relevant materials [4].
ꢀ
C
actions. 2009 Wiley Periodicals, Inc. Heteroatom Chem
In this paper, we describe the synthesis of
α-phosphonyl phosphonium and sulfonium ylides
starting from trialkylphosphites and phospho-
20:164–171, 2009; Published online in Wiley InterScience
(www.interscience.wiley.com). DOI 10.1002/hc.20530
nodithioformates and their behavior under thermal
conditions, leading to α-sulfanyl methylene bis-
phosphonates.
INTRODUCTION
Mixed phosphorus- and sulfur-containing com-
pounds have been shown to be useful synthetic tools
and also to exhibit interesting biologic properties,
due to the diversity of functions and oxidation
states involving the two heteroatoms [1]. Among
them, phosphonodithioesters are versatile reagents
through their use in various reactions such as
thiophilic addition of nucleophiles, thioacylation
RESULTS AND DISCUSSION
Synthesis of Phosphonium Ylides 4–6 and
Sulfonium Ylides 7–9
α-Sulfanyl-α-phosphonyl phosphonium ylides 4–6
were obtained in quantitative yields by the reaction
between two equivalents of a trialkylphosphite with
phosphonodithioformates 1–3, which were easily
synthesized according to the method described by
Grisley [5]. The reaction proceeds by a thiophilic
addition followed by desulfurization (Scheme 1)
and the trialkyl thiophosphate, which is also gen-
erated in the reaction, can be efficiently removed
under vacuum [3b].
Correspondence to: Michel Vazeux; e-mail: michel.vazeux@
ensicaen.fr.
Contract grant sponsor: Ministe`re de la Recherche et des
Nouvelles Technologies.
Contract grant sponsor: CNRS.
Contract grant sponsor: Re´gion Basse-Normandie.
Contract grant sponsor: European Union (FEDER funding).
2009 Wiley Periodicals, Inc.
c
ꢀ
164

Synthesis of α-Phosphonylated Phosphonium and Sulfonium Ylides: Study of Their Thermal Behavior 165
2 equiv. (R1O)3P
Reactivity of α-Methylsulfanyl Phosphonium
Ylides 4 and 6 under Thermal Conditions
O
O
S
C
THF
(R1O)2P
C
P(OR1)3
(R1O)2P
SR2
1
The phosphonium ylides 4 and 6 differ by the
nature of the alkoxyphosphonium group (ethyl
versus isopropyl). A high stability of these ylides
was observed at room temperature, but upon
heating at 110◦C (Scheme 3) ylide 4 afforded, beside
methylsulfanyl methylene bis-phosphonate 11, the
bis-phosphonylated sulfonium ylide 10, and an
unidentified product A (31P NMR, δ = 20 ppm). Per-
centages of the three products 10, 11, A, and of the
starting ylide 4 have been shown to be dependent on
the heating time. Results are presented in Table 1.
After 18 h of heating without ethyl iodide, three
products were observed albeit a low conversion was
achieved (Table 1, entry 1). After 150 h, the reaction
was complete and only methylsulfanyl methylene
bis-phosphonate 11 along with a small amount
of compound A was formed. This result suggests
the formation of methylene bis-phosphonate 11
from the intermediate sulfonium ylide 10 (Table 1,
entry 2). When the phosphonium ylide 4 was heated
for 18 h in refluxing toluene in the presence of 1
equiv of ethyl iodide, 11 and 10 were formed in a
3:2 ratio (Table 1, entry 3). The addition of ethyl
iodide increases the reaction rate (Table 1, entry 1
versus entry 3) very likely by favoring the formation
of the sulfonium ylide 10. Prolonged heating (120 h;
Table 1, entry 4) enabled the selective formation of
the methylsulfanyl bis-phosphonate 11 via 10, after
addition of 1 equiv of ethyl iodide.
(R O)3PS
SR2
1: R1 = Et, R2 = Me
2: R1 = Me, R2 = CD3
3: R1 = i-Pr, R2 = Me
4: R1 = Et, R2 = Me
5: R1 = Et, R2 = CD3
6: R1 = i-Pr, R2 = Me
SCHEME 1
Then, the phosphonium ylides 4–5 were con-
verted into sulfonium ylides 7–9 by S-alkylation with
alkyl halides (Scheme 2). The reaction was com-
pletely selective, and no C-alkylation products were
detected.
The addition at room temperature in THF of
methyl iodide or benzyl bromide to phosphonium
ylide 4 leads to the sulfonium ylides 7 and 8 in
65% and 76% yield, respectively. Similarly, alkyla-
tion of 5 with deuterated methyl iodide led to the
expected sulfonium ylide 9. The overall reaction in-
volves S-alkylation and subsequently the Arbuzov-
type dealkylation of the trialkoxyphosphonium in-
termediate [3c]. It is worth to note that ethyl iodide
or ethyl bromide generated during the reaction is
not reactive enough under these conditions (room
temperature, THF) to react with the starting phos-
phonium ylides.
R1
X
O
O
O
O
O
1X
R3X
(R1O)2P
(R1O)2P
(R1O)2P
P(OR1)3
C
S
P(OR1)2
C
S
P(OR1)2
C
SR2
R2
R3
R3
R2
4: R1 = Et, R2 = Me
4: R1 = Et, R2 = Me
5: R1 = Et, R2 = CD3
7: R1 = Et, R2 = R3 = Me (65%)
8: R1 = Et, R2 = Me, R3 = Bn (76%)
9: R1 = Et, R2 = R3 = CD3 (75%)
SCHEME 2
O
O
O
H
C
O
O
(R1O)2P
(R1O)2P
(R1O)2P
P(OR1)2
P(OR1)3
C
S
P(OR1)2
+
+ A
C
SMe
SMe
R1
Me
4: R1 = Et
6: R1 = i-Pr
11: R1 = Et
12: R1 = i-Pr
10: R1 = Et
13: R1 = i-Pr (not observed)
SCHEME 3
Heteroatom Chemistry DOI 10.1002/hc

166 Sene, Masson, and Vazeux
TABLE 1 Transformation of Ylide 4 into 11, 10, and A, under Thermal Conditions, with or without Addition of Ethyl Iodide
Entry
Heating Time (110◦C)
Added Ethyl Iodide
4 (%)
11 (%)
10 (%)
A (%)
1
2
3
4
18 h
150 h
18 h
0
0
75
0
0
13
83
60
3
0
40
0
5
10
0
1 equiv
1 equiv
120 h
0
100
0
R4
H2C
CH
H
O
O
O
O
H
(R1O)2P
CH2=CH-R4
(R1O)2P
C
P(OR1)2
C
P(OR1)2
+
SMe
SMe
R4 = H
R4 = Me
4: R1 = Et
6: R1 = i-Pr
11: R1 = Et
12: R1 = i-Pr
SCHEME 4
Compared to 4, phosphonium ylide 6 led only
to the methylsulfanyl tetraisopropyl methylene
bis-phosphonate 12 (Scheme 3). The formation of
α-phosphonylated sulfonium ylide 13 was never
observed. The formation of sulfanyl methylene
bis-phosphonates 11 and 12 can be explained by a
mechanism involving an intramolecular protonation
of the corresponding ylides with a proton coming
from one alkoxy group of the phosphonium moiety
producing ethylene and propylene, respectively
(Scheme 4) [6,7]. This approach using phospho-
nodithioformates and trialkylphosphites as simple
starting materials can be considered as a convenient
alternative to the previously reported methods to
access alkylsulfanyl methylene bis-phosphonates
[3b,8].
The reactivity of phosphonium ylides under
thermal conditions is often related to a C-alkylation
involving the transfer of an alkyl group from the
phosphonium moiety to the carbon of the ylide
[9]. To examine the possibility of such a reac-
tion, the crude mixture obtained after heating the
triethoxyphosphonium ylide 4 during 150 h was
analyzed by GC/MS. The analysis of the mixture of
bis-phosphonate 11 and A (Table 1, entry 2) by mass
spectroscopy showed two mass peaks of 334 and
362. The mass of 362 and the observed chemical
shift near 20 ppm in the 31P NMR spectrum can
be assigned to α-ethyl-α-methylsulfanyl methylene
tetraethyl bis-phosphonate, formed from 4 by an
intramolecular C-alkylation (Scheme 5).
sulfonium ylide 10 was prepared independently
in two steps following the procedures shown in
Schemes 1 and 2. Thus, the reaction of triethylphos-
phite with ethyl diethylphosphonomethanedithioate
followed by S-methylation with methyl iodide of the
resulting phosphonium ylide afforded 10 in high
yield. Upon heating at 110◦C for 6 days, sulfonium
ylide 10 generated only methylsulfanyl methylene
bis-phosphonate 11 and ethylene. The ethylene
gas evolving during the reaction was transformed
into 1,2-dibromoethane by trapping with bromine.
These results are in agreement with the mechanism
proposed for the transformation of ylide 4 under
thermal conditions. The reaction involves two
intramolecular processes, namely S-alkylation and
subsequent protonation, leading to 11 and ethylene
via sulfonium ylide 10 (Scheme 6).
Obviously, such a mechanism based on the
transfer of an alkyl group toward sulfur, is unlikely
to occur with the triisopropoxyphosphonium ylide
6. Thus, the conversion of the α-phosphonylated
sulfonium ylide 10 into methylene bis-phosphonate
11 appears to be an αβꢁ elimination-type reaction
Et
O
O
O
O
Et
C
(EtO)2P
(EtO)2P
P(OEt)2
C
P(OEt)2
SMe
SMe
To complete the mechanistic study of the be-
havior of the triethoxyphosphonium ylide 4 under
thermal conditions (Scheme 3), bis-phosphonylated
A
4
SCHEME 5
Heteroatom Chemistry DOI 10.1002/hc

Synthesis of α-Phosphonylated Phosphonium and Sulfonium Ylides: Study of Their Thermal Behavior 167
O
CH2=CH2
O
O
O
O
P(OEt)2
H
H
C
(EtO)2P
C
P(OEt)2
O
(EtO)2P
C
(EtO)2P
P(OEt)2
S
S
SMe
Me
Me
Et
4
10
11
SCHEME 6
O
O
O
O
O
H
H
O
(110°C)
(EtO)2P
C
S
P(OEt)2
(3 weeks)
CH3
(EtO)2P
H3C
(EtO)2P
C
S
P(OEt)2
+
CH2
C
P(OEt)2
SCH3
11
H3C
CH2
7
7-bis
SCHEME 7
analogue to the reaction previously reported for the
analog α,α-dicarboxylated sulfonium ylide [10].
O
O
O
O
D
C
(110°C)
(3 weeks)
(EtO)2P
C
S
P(OEt)2
(EtO)2P
+
P(OEt)2
CD2
SCD3
14
D3C
CD3
Reactivity of Bis-Phosphonylated Sulfonium
Ylides 7–9 under Thermal Conditions
9
Similarly to the sulfonium ylide 10, the stabilized
ylides 7–9 led to α-alkylsulfanyl methylene bis-
phosphonates upon heating.
SCHEME 8
Dimethylsulfonium ylide 7 was found to be very
stable and could even be purified by flash distilla-
tion. However, submitted to a prolonged heating (3
weeks at 110◦C), it led to the bis-phosphonate 11 as
a single product (Scheme 7). The reaction proceeds
very likely through a protonation of the ylide 7 by
one proton of the methyl substituent of the sulfo-
nium group, leading to new ylide 7-bis (isomer of
7), which would be decomposed upon heating into
bis-phosphonate 11 and carbene. When the reaction
was carried out in a sealed tube in the presence of cy-
clohexene, a GC/MS analysis of the mixture revealed
the formation of norcarane albeit in small amount.
The reactivity of the deuterated ylide 9 under
identical thermal conditions also confirmed the
mechanism proposed above, as the deuterium in-
corporated on the central carbon of product 14 can
only come from one of the CD3 group (Scheme 8).
In the case of S-benzyl-S-methyl sulfonium
ylide 8, upon heating at 110◦C during 1 week,
bis-phosphonates 11 and 15 were formed in 60%
and 30% yield, respectively (Scheme 9).
however, not be trapped with cyclohexene. The
methylene bis-phosphonate 15 probably resulted
from a Stevens [1,2]-rearrangement as previously
reported in bis-carboxylate sulfonium ylide series
[10,11].
CONCLUSION
This article described a study of the thermal be-
havior of stabilized α-sulfinylated phosphonium
and bis-phosphonylated sulfonium ylides which
enabled, beside offering a new access to alkylsul-
fanyl methylene bis-phosphonates, to understand
the various mechanisms involved in the transfor-
mations. They were found to be largely dependent
on the nature of the substituents present on the
phosphonium and sulfonium moieties.
The formation of α-alkylsulfanyl methylene
bis-phosphonates by thermal treatment of phos-
phonium and sulfonium ylides results mainly
from simultaneous intramolecular protonation and
elimination of an alkene or a carbene, respectively.
However, we found that phosphonium ylides can
be initially converted to some extent into sulfonium
ylides under these conditions.
As in the previous studied cases, the formation
of bis-phosphonate 11 can be explained by simulta-
neous intramolecular protonation and elimination
of the corresponding carbene (PhCH:), which could,
Heteroatom Chemistry DOI 10.1002/hc

168 Sene, Masson, and Vazeux
O
O
O
O
O
H
C
O
Bn
C
(110°C)
(EtO)2P
Bn
C
S
P(OEt)2
(EtO)2P
+ (EtO)2P
P(OEt)2
P(OEt)2
(1 week)
SMe
SMe
Me
8
11
15
SCHEME 9
EXPERIMENTAL
General
S-Methyl Diethylphosphonodithioformate 1.
1
Bp0.1: 112–117◦C. Yield: 57%. H (CDCl3) δ: 1.36 (t,
3 JHH = 7, 6H, CH3CH2 O); 2.71 (s, 3H, SCH3); 4.22
3
3
Samples were dissolved in CCl4, CDCl3, or C6D6
with internal TMS. The NMR spectra were recorded
in with a Bruker DPX 250 spectrometer. The
chemical shifts (δ) are expressed in ppm, and the
coupling constants (J) are given in hertz (Hz);
conventional abbreviations are used. Infrared spec-
tra (IR) were recorded using a Perkin–Elmer 684
spectrophotometer, absorption peaks frequencies ν
are expressed in cm−1. Mass spectra were performed
with either a Varian CH 5 or a Nermag Riber R10
mass spectrometer. Electronic impact experiments
were recorded at 70 eV (m/z and relative abundance
in percentage are given). Chemical ionization was
obtained using ammoniac. Melting points (Mp) were
measured with a Ko¨fler or a Gallzenkamp apparatus
and are uncorrected. Boiling points (Bp) are given
in centigrade (◦C), and the corresponding pressure
is expressed in mmHg. Elementary analyses were
performed following the method of Debal and
Levy [12]. Flash chromatography was performed
with Merck 60 (63–200 μm) silica gel following
the method of Zubrick [13]. All reactions were
carried out using standard techniques. Solvents
were purified prior to use by conventional methods.
(dq, JHH ∼ JHP = 7, 4H, CH3CH2 O). 31P (CDCl3) δ:
−2.41. 13C (CDCl3) δ: 16.15 (d, 3 JCP = 7, CH3CH2 O);
2
19.91 (s, SCH3); 64.83 (d, JCP = 7.3, CH3CH2 O);
1
241.75 (d, JCP = 135.5, C S). IR (film): 2980; 2930;
2910; 2860; 1630; 1475; 1440; 1365; 1250 (P O);
1160 (P OEt); 1095 (C S). Anal.: C6H13O3PS2: S% :
Calcd : 28.9; Found : 27.98.
S-Methyl(d3)-diethylphosphonodithioformate 2.
Bp0.1: 118◦C. Yield: 60%. 1H (CDCl3) δ: 1.4 (t,
3
3
3 JHH = 7, 6H, CH3CH2 O); 4.26 (qi, JHH ∼ JHP = 7,
4H, CH3CH2 O). 31P (CDCl3) δ: −2.48. 13C (CDCl3)
3
δ: 16.27 (d, JCP = 5.89, CH3CH2 O); 64.61 (d,
2 JCP = 6.78, CH3CH2 O); 230.05 (d, JCP = 175.7,
1
C S). IR (film): 2985; 2920; 2900; 2240; 2110; 1640;
1470; 1440; 1390; 1255 (P O); 1160 (P OEt); 1100
(C S); 1050; 970. Mass m/z (%): M+• 231 (30); 213
(6); 185 (4); 183 (15); 181 (18); 155 (4); 153 (13); 137
(20); 121 (6); 109 (48); 97 (4); 96 (10); 95 (32); 94
(100); 93 (21); 91 (20).
S-Methyl-diisopropylphosphonodithioformate 3.
Bp0.02: 123◦C. Yield: 58%. 1H (CDCl3) δ: 1.33 and
3
1.40 (d, JHH
∼
4 JHH = 7, 6H, (CH3)2CH O); 2.66
3
(s, 3H, SCH3); 4.82 (octuplet, JHH
∼
3 JHP = 7, 2H,
(CH3)2CH O). 31P (CDCl3) δ: −4.25. 13C (CDCl3)
3
Synthesis of Phosphonodithioformates 1–3
δ: 19.24 (d, JHP = 3, SCH3); 23.66 and 24.07
3
2
(d, JCP = 4.6 (CH3)2CH O); 73.60 (d, JCP = 6.7,
Phosphonodithioformates 1–3 were synthesized ac-
cording to the method of Grisley [5].
1
(CH3)2CH O); 231.73 (d, JCP = 177.3, C S). IR
(film): 1255 (P O); 1180; 1140; 1095 (C S); 990
(P OiPr). Mass m/z (%): M+• 256 (33); 214 (43); 199
(19); 123 (61); 107 (14); 91 (100); 59 (90).
To a stirred suspension of sodium hydride (0.22
mol) in dry THF (200 mL), dialkylphosphite (0.20
mol) dropwise was added. After 3 h of stirring, the
resulting solution was added onto carbon disulfide
(CS2; 0.10 mol) cooled at –10◦C. Methyl iodide or
CD3I (0.21 mol) was then added to the dark red
solution, and stirring was continued for 3 h. The
solution was poured onto 300 mL of saturated
aqueous NH4Cl and extracted three times with
ether. The combined organic layers were dried
over magnesium sulfate, filtered and the solvent
was evaporated. The phosphonodithioformates 1–3
(dark red liquids) were purified by distillation.
Syntheses of Trialkoxyphosphonium Ylides 4–6
To a solution of trialkylphosphite (5.90 mmol)
in THF (4 mL) at 0◦C, dropwise S-methyl-
dialkylphosphonodithioformate 1–3 (2.80 mmol)
was added. The temperature was allowed to rise
slowly to room temperature. The solvent and the
trialkylthiophosphate were eliminated under re-
duced pressure (Bp0.01 = 67◦C), and the α-sulfanyl
Heteroatom Chemistry DOI 10.1002/hc

Synthesis of α-Phosphonylated Phosphonium and Sulfonium Ylides: Study of Their Thermal Behavior 169
phosphonium ylides 4–6 (viscous oils) were obtained
in quantitative yield.
ylide 4 (0.303 g, 0.84 mmol) in 1 mL of THF. After
48 h, the solvent was removed and the crude sulfo-
nium ylide 7 was obtained as a viscous oil.
Triethoxyphosphoranylidene Methylsulfanyl Di-
Bp0.01: 165◦C. Yield: 65%. 1H (CDCl3) δ: 1.26
3
ethyl Methylphosphonate 4. 1H (CDCl3) δ: 1.26
(t, JHH = 7, 6H,CH3CH2 O); 2.86 (s, 6H, SCH3);
(t, JHH = 7, 6H, CH3CH2 O); 1.36 (t, JHH = 7,
3.86 (M, CH3CH2 O). RMN 31P (CDCl3) δ: 24.58.
13C (CDCl3) δ: 16.15 (m, CH3CH2 O); 24.45 (t,
1 JCP = 203, P C P); 33.17 (t, 3 JCP = 1.4, SCH3); 61.05
(m, CH3CH2 O). IR (film): 2980; 2930; 2900; 1735;
1645; 1475; 1440; 1390; 1360; 1290; 1215 (P O);
1160 (P OEt); 1095; 1025; 960; 795. Mass m/z (%):
348 (8); 333 (8); 288 (10); 277 (16); 261 (6); 242 (6);
233 (5); 221 (9); 215 (8); 152 (10); 109 (10); 58 (25);
43 (100); 42 (9). Anal.: C11H26O6P2S.
3
3
3
6H,CH3CH2 O); 1.93 (m, 3H, SCH3); 3.9 (qi, JHH
3
∼
3 JHP = 7, 4H, CH3CH2 OP); 4.2 (qi, JHH
∼
3 JHP = 7, 4H, CH3CH2 OP+). 31P (C6D6) δ: 28.50
2
2
(d, JPP = 146.80, P); 51.09 (d, JPP = 146.80, P+).
13C (C6D6) δ: 16.00 (d, JCP = 6.8, CH3CH2 OP);
3
16.74 (d, JCP = 6.7, CH3CH2 OP+); 23.21 (t, JCP
=
3
3
3 JCP = 3, SCH3); 20.62 (t, 1 JCP = 220, P C P+); 64.26
2
2
(d, JCP = 6.6, CH3CH2 OP); 64.84 (d, JCP = 6.7,
CH3CH2 OP+). IR (film): 2980; 2910; 1640; 1480;
1445; 1425; 1390; 1365; 1280 (P O); 1160 (P OEt);
1040. Mass m/z (%): M+• 362 (35); 334 (16); 319 (17);
306 (6); 291 (12); 288 (14); 263 (9); 235 (8); 221 (9);
204 (10); 198 (12); 152 (12); 141 (9); 121 (9); 109 (13);
99 (7); 93 (11); 81 (14); 65 (30); 45 (11); 43 (30); 32
(16); 29 (28); 25 (69); 27 (16); 18 (100).
Element
C
H
O
S
Calcd (%)
37.20 7.52 27.50 9.20
Found (%) 37.27 7.74 26.99 9.32
Benzylmethylsulfanylidene Methylene Tetraethyl
Bis-Phosphonate 8. To a solution of phosphonium
ylide 4 (3.16 g, 8.74 mmol) in THF (8 mL), 1.65 g
(9.70 mmol) of benzyl bromide was added at room
temperature. After 150 h of stirring, the solvent and
the excess of benzyl bromide were removed under
vacuum. White crystals of pure ylide 8 were ob-
tained, washed with pentane, and dried.
Triethoxyphosphoranylidene Methyl(d3)sulfanyl
Diethyl Methylphosphonate 5. 1H (C6D6) δ: 0.98–
1.37 (m, CH3CH2 O); 3.85–4.40 (m, CH3CH2 O).
2
31P (C6D6 + CCl4) δ: 28.66 (d, JPP = 147.5, P); 51.15
2
(d, JPP = 147.5, P+). 13C (C6D6 + CCl4) δ: 15.99
3
3
(d, JCP = 2.9, CH3CH2 OP); 16.27 (d, JCP = 2.5,
CH3CH2 OP+); 62.54 (d, JCP = 4.9, CH3CH2OP);
2
63.45 (d, 2 JCP = 6.4, CH3CH2OP+).
Mp: 73–75◦C. Yield: 76%. 1H (CDCl3) δ: 1.13–1.15
(m, CH3CH2 O); 2.86 (s, 3H, SCH3); 3.50–4.18 (m,
Triisopropyloxyphosphoranylidene
Methylsul-
CH3CH2 O); 4.60 (s, PhCH2); 7.30–7.50 (M, Har). 31
P
fanyl Diisopropylmethylphosphonate 6. 1H (C6D6)
3
(CDCl3) δ: 25.46. 13C (CDCl3) δ: 16.34 (t, JCP = 3.7,
3
δ: 1.28–1.40 (m, JHH = 7, 12H, (CH3)2CH O); 2.16
1
CH3CH2 O); 22/95 (t, JCP = 203.7, P C P); 30.25
(m, 3H, SCH3); 4.18 (M, (CH3)2CH O). 31P (C6D6)
3
(t, JCP = 1.6, SCH3); 53.35 (s, PhCH2) 61.02 (m,
2
2
δ: 28.14 (d, JPP = 149.9, P); 48.25 (d, JPP = 149.9,
CH3CH2 O); 128.9–131 (M, Car). Mass m/z (%):
M+•424 (60); 423 (18); 378 (9); 377 (11); 333 (8);
330 (17); 304 (5); 248 (6); 22 (16); 93 (11); 91 (100);
81 (12); 65 (47); 61 (9). Anal.: C17H30O6P2S
1
P+). 13C (C6D6) δ: 22.85 (d, JCP = 220, P C P);
23.12–23.85 (M, SCH3 and (CH3−2CH O)); 68.05
2
2
(d, JCP = 5.2, (CH3)2CH OP); 73.62 (d, JCP = 7.5,
(CH3)2CH OP+). IR (film): 2980; 2930; 2870; 1635;
1465; 1335; 1320; 1215 (P O); 1160 (P OEt); 1175;
1140(P OiPr); 1105; 1080; 990. Mass m/z (%): M+•
432(14); 390(21); 373(5); 348(14); 344(14); 306(23);
303(17); 264(43); 261(14); 249 (6); 247 (5); 226 (5);
224 (7); 223 (6); 222 (100); 221 (18); 219 (21); 218
(10); 207 (16); 205 (21); 204 (30); 203 (8); 177 (39);
176 (13); 159 (12); 158 (9); 146 (6); 139 (8); 125 (10);
123 (10); 99 (12).
Element
C
H
O
S
Calcd (%)
48.10 7.12 22.61 7.55
Found (%) 48.82 7.13 21.99 7.48
Dimethyl-(d6)sulfanylidene Methylene Tetraethyl
Bis-Phosphonate 9. Compound 9 was obtained ac-
cording to the method described for 7 using CD3I
instead of CH3I.
Synthesis of Bis-Phosphonylated Sulfonium
Ylides 7–9
Yield: 69%. 1H (CDCl3) δ: 1.13–1.46 (m,
CH3CH2O); 3.73–4.60 (m, CH3CH2O). 31P (C6D6+
THF) δ: 24.59. 13C (CDCl3) δ: 16.40 (s, CH3CH2O);
61.06 (m, CH3CH2O).
Dimethylsulfanylidene Methylene Tetraethyl Bis-
Phosphonate 7. Methyl iodide (0.142 g, 1 mmol)
was added at room temperature to phosphonium
Heteroatom Chemistry DOI 10.1002/hc

170 Sene, Masson, and Vazeux
P CH P); 71.90–72.40 (m, (CH3)2CH O). Mass m/z
(%): M+•390 (13); 345 (6); 344 (35); 303 (41); 261
(33); 260 (6); 222 (10); 221 (6); 219 (41); 218 (18);
205 (21); 204 (17); 203 (7); 177 (66); 176 (20); 159
(20); 158 (21); 142 (26); 141 (42); 127 (14); 124 (14);
123 (20); 91 (8); 78 (8); 65 (11); 43 (100). IR (film):
2980; 2930; 2870; 1725; 1640; 1465; 1450; 1385; 1370;
1355; 1315; 1250 (P O); 1175 (P OiPr); 1140; 1030;
975. Anal.: C32H24O6P2S
Synthesis of the Bis-Phosphonylated Sulfonium
Ylide 10
Compound 10 was obtained according to the above
procedure described for 7, starting from ethyl
diethylphosphonomethanedithioate instead of its
methyl analog 1.
Yield: 92%, isolated as a viscous oil.
Ethylmethylsulfanylidene Methylene Tetraethyl
Bis-Phosphonate 10. 1H (CDCl3) δ: 1.30 (t, 3 JHH = 7,
3
12H, CH3CH2 O); 1.33 (t, JHHA
∼
3 JHHB = 7, 3H,
Element
C
H
O
S
CH3CHAHB S); 2.84 (s, 3H, SCH3); 2.98 (ddq, 1H,
4 JHAP = 2, JHAHB = 12, JHHA = 7, S–CHA); 3.54 (ddq,
2
3
Calcd (%)
43.06 8.26 24.58 8.21
4
2
3
1H, JHBP = 2, JHAHB = 12, JHHB = 7, S–CHB); 3.71–
Found (%) 42.62 8.13 25.22 8.25
4.29 (m, 6H, CH3CH2 O). 31P (CDCl3) δ: 26.07. 13C
3
(CDCl3) δ: 9.59 (s, CH3CH2–S); 16.38 (t, JCP = 3.7,
1
CH3CH2 O); 23,08 (t, JCP = 203.7, P C P); 31.9
ACKNOWLEDGMENT
2
(∼s, SCH3); 61.08 (t, JCP = 2.8, CH3CH2 O); 67 (s,
We thank Dr. Patrice Marchand, a former coworker
of the group, for helpful discussions.
CH3CH2–S).
Synthesis of Tetraalkyl Methylsulfanyl Methylene
Bis-Phosphonates 11 and 12
REFERENCES
Bis-phosphonates 11 and 12 were obtained by
heating at 110◦C phosphonium ylides 4 and 6 or
sulfonium ylide 7.
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Tetraethyl
Methylsulfanyl
Methylene
Bis-
Phosphonate 11. Purified by chromatography
on Florisil (eluent: acetone/petroleum ether,
1
3
20/80). Yield: 68% H (CDCl3) δ: 1.35 (t, JHH = 7,
6H, CH3CH2 O); 2.33 (s, 3H, SCH3); 2.28 (t,
2 JHP = 22, 1H, P CH P); 4.16 (dq ∼ qi, JHH
∼
3
3 JHP = 7, 4H, CH3CH2 O). 31P (CDCl3) δ: 17.58.
13C (CDCl3) δ: 15.39 (m, CH3CH2 O); 16.3 (t,
3 JCP = 2.7, SCH3); 37.61 (t, JCP = 138, P CH P);
1
62.56 (m, CH3CH2 O). Off decoupling: 37.61 (q,1 JCH
∼ JCP = 138 Hz, P CH P). Mass m/z (%): M+•334
1
(12); 289 (11); 288 (76); 261 (24); 233 (14); 152 (38);
141 (12); 101 (19); 58 (27); 43 (100); 28 (38). IR
(film): 2970; 2930; 2910; 2870; 2230; 1700; 1470;
1440; 1420; 1390; 1245 (P O); 1160 (P OEt); 1095;
1035; 970. Anal.: C10H24O6P2S: S% Calcd : 9.59;
found : 9.47.
Tetraisopropyl Methylsulfanyl Methylene Bis-
Phosphonate 12. Purified by chromatography on
Florisil (eluent: ethyl acetate/ petroleum ether
15/85). Yield: 58%.
1H (CDCl3) δ: 1.36 (m, 6H, (CH3)2CH O); 2.29
2
(s, 3H, SCH3); 2.76 (t, JHP = 22, 1H, P CH P);
4.50–5.16 (m, 2H, (CH3)2CH O). 31P (CDCl3) δ:
3
15.98. 13C (CDCl3) δ: 17.83 (t, JCP = 2.8, SCH3);
23.71–24.32 (m, (CH3)2CH O); 40.22 (t, 1 JCP = 139.8,
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