Silylcupration of 1-alkynylphosphine oxides: Stereo- and regioselective synthesis of β-silyl substituted vinylphosphine oxides

Article abstract of DOI:10.1055/s-2005-924763

β-Silyl substituted vinylphosphine oxides were prepared stereo- and regioselectively by the silylcupration of 1-alkynylphosphine oxides followed by hydrolysis or by reacting with other electrophiles. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2005-924763

PAPER
231
Silylcupration of 1-Alkynylphosphine Oxides: Stereo- and Regioselective
Synthesis of b-Silyl Substituted Vinylphosphine Oxides
S
a
ynthesis of
b
-Sily
i
l
Subst
a
itute
d
V
iny
n
lphosphine Oxide
s
Huang,*a,b Lubin Xua
Department of Chemistry, Zhejiang University, Xixi Campus, Hangzhou 310028, P. R. of China
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
Shanghai 200032, P. R. of China
b
Fax +86(571)88807077; E-mail: huang@mail.hz.zj.cn
Received 24 May 2005; revised 5 August 2005
of silicon synthons of great potential.13 Moreover, the in-
termediate cuprates resulting from syn-addition of the si-
lylcuprate to acetylene react with a great variety of
electrophiles to give vinylsilanes.12,13 We report herein a
synthetic route for the preparation of b-silyl substituted
vinylphosphine oxides, which are versatile synthetic re-
agents serving as not only vinylphosphine oxides but also
as vinylsilanes, by the Michael addition of organosilyl-
copper(I) reagents to 1-alkynylphosphine oxides14.
Abstract: b-Silyl substituted vinylphosphine oxides were prepared
stereo- and regioselectively by the silylcupration of 1-alkynylphos-
phine oxides followed by hydrolysis or by reacting with other elec-
trophiles.
Key words: silylcupration, 1-alkynylphosphine oxide, b-silyl sub-
stituted vinylphosphine oxides
Stereoselective synthesis of substituted alkenes has al-
ways been an interesting topic in organic synthesis, in
which the organometalation of acetylenes is one of the
most efficient routes to stereo-defined alkenes.1 Among
the organometalation reagents, organocopper reagents
have received an especially great deal of attention regard-
ing cis-conjugate addition reactions with acetylenic com-
pounds.2 In the case of functionalized acetylenes, most
reactions with organocopper reagents also undergo a fac-
ile cis-addition.3
Preliminary experiments involved the treatment of 1-
alkynylphosphine oxides15 with organosilylcopper(I) re-
agents, prepared in situ from CuCN and 2 equivalents of
organosilyllithium,16 followed by hydrolysis with saturat-
ed ammonium chloride solution (Scheme 1). The results
are summarized in Table 1.
As indicated in Table 1, the Michael addition proceeded
smoothly and was complete within 30 minutes with orga-
nosilylcuprates at –78 °C in THF. However, probably due
to steric hindrance of the bulky group, a low yield was ob-
served along with recovery of starting material for entry 3.
In all cases, organosilylcopper(I) reagents attacked b-po-
sition of 1-alkynylphosphine oxides exclusively. The re-
gioselectivity can be rationalized in terms of carbanion
stabilization by the phosphine oxides. A cis-addition was
found when 1-alkynylphosphine oxides reacted with or-
ganosilylcopper(I) reagents. The cis-stereoselectivity in
these reactions and the E configuration of 3a and 3b were
confirmed by NOE experiments, which showed the corre-
lation between the vinylic proton and the protons of tri-
methylsilyl or phenyldimethylsilyl group, while there is
no correlation between the vinylic proton and the methyl-
ene group.
Our group has prepared several kinds of functionalized vi-
nyl compounds by hydrozirconation,4a hydrotelluration,4b
carbomagnesiation,5 carbocupration,6 and selenomag-
nesiation7 of various functionalized acetylenes, to afford
stereo-defined polysubstituted alkenes.
Unsaturated phosphorus compounds containing various
functional groups have been widely studied due to their
synthetic and biological usefulness.8 On the other hand,
functionalized vinylphosphine oxides are useful synthetic
intermediates for nucleophilic addition9 and cycloaddition
reactions.10 And some derivatives of vinylphosphine ox-
ides can be used as biologically active compounds.11 In
the past years the organosilylcupration of acetylenes has
provided efficient procedures for introducing organosilyl
group to organic molecules,12 giving rise to a wide range
R1
R2Me2Si
P(O)Ph2
H
R1
R2Me2Si
P(O)Ph2
CuLi
(R2Me2Si)2CuCNLi2
H3O+
R1
P(O)Ph2
2
1
3
Scheme 1
SYNTHESIS 2006, No. 2, pp 0231–0236
x
x
.
x
x
.2
0
0
5
Advanced online publication: 21.12.2005
DOI: 10.1055/s-2005-924763; Art ID: F09405SS
© Georg Thieme Verlag Stuttgart · New York

232
X. Huang, L. Xu
PAPER
Table 1 Reaction of Organosilylcopper(I) Reagents with 1-Alkyn-
1-Halovinylphosphine oxides 4a–f were obtained
smoothly by treating 2 with iodine (or NBS, NCS). When
electrophiles such as phenylselenyl bromide and phenyl-
telluryl iodide were added, 1-phenylchalcogenovi-
nylphosphine oxides 4g and 4h were formed.17 Allylation
products of 4i and 4j were also generated with allyl bro-
mide in good yields. Even the arylation product 4k was
produced by the reaction with diphenyliodonium chloride
in good yield (Table 2, entry 11), but with acetylenylphe-
nyliodonium tosylate we did not obtain the corresponding
product. The intermediate cuprate 2 did not react with car-
bonyl compounds. Attempts to trap this vinylcopper(I) in-
termediates with benzaldehyde, acetyl chloride and
benzoyl chloride led only to compound 3. At the same
time, no anticipated products were obtained from the re-
actions of other electrophiles such as methyl iodide,
methyloxirane or a,b-unsaturated ketones. This is proba-
bly due to the coordination between the phosphine oxide
function and copper,18 which could also partially explain
why only some activated electrophilic reagents react with
intermediate 2.
ylphosphine Oxides (E+ = H+)
Entry
R1
R2
Producta
3a
Yield (%)b
1
2
3
4
5
6
7
EtOCH2
EtOCH2
Ph
Me
Ph
82
78
22c
80
76
89
81
3b
Me
Me
Ph
3c
n-C4H9
n-C4H9
MeOCH2
MeOCH2
3d
3e
Ph
3f
Me
3g
a Other isomers were not detected in NMR studies.
b Isolated yield based on 1.
c The starting material was recovered to an extent of 67%.
The dimetalated intermediates 2 are important intermedi-
ates because they can react with a series of electrophiles
to give the polysubstituted vinylphosphine oxides with re-
tention of configuration (Scheme 2). We have thus further
investigated the reactions of intermediate 2 with several
electrophiles. Results were summarized in Table 2.
The stereochemistry of the reaction was unequivocally es-
tablished by NOESY spectra of compound 4i and 4j. The
NOESY spectra of compounds 4i and 4j show that there
is a strong correlation between the allylic protons of the
allyl group and the protons of trimethylsilyl or phenyldi-
methylsilyl group, while no correlation was found be-
tween the allylic protons of the allyl group and R1 group.
Table 2 Reaction of Organosilylcopper(I) Reagents with 1-Alkyn-
ylphosphine Oxides (Electrophile = E+)
Entry
R1
R2
E+
Product Yield (%)a
1-Halovinylphosphine oxide 4a–f are very useful inter-
mediates, for example, the Sonogashira cross-coupling
reaction of a-iodovinylphosphine oxide 4a with phenyl-
acetylene in the presence of catalytic amount of Pd/Cu(I)
provided a novel kind of enyne compound 5 containing
phosphorus and silyl functional groups (Scheme 3).
1
2
EtOCH2
n-C4H9
MeOCH2
Ph
Me
Me
Me
Me
Me
Ph
I
4a
4b
4c
4d
4e
4f
79
75
80
24
68
82
69
78
76
75
62
I
3
I
4
I
Besides the coupling reaction, the carbomethoxylation of
haloalkene 4c also proceeded smoothly and introduced a
CO2Me group into the molecule, which cannot be gener-
ated directly by the reaction of intermediate 2 with methyl
chloroformate (Scheme 4).
5
EtOCH2
n-C4H9
n-C4H9
n-C4H9
n-C4H9
MeOCH2
MeOCH2
Br
6
Cl
7
Me
Me
Me
Ph
SePh
TePh
4g
4h
4i
In conclusion, cis-silylcupration of 1-alkynylphosphine
oxides and further reaction with electrophiles provide an
efficient, regio- and stereoselective method for the synthe-
sis of synthetically useful b-silyl substituted vinylphos-
phine oxides in a one-pot process. The reactions of
intermediate 2 with other electrophiles to synthesize vari-
ous substituted b-silyl substituted vinylphosphine oxides
8
9
Br
Br
10
11
4j
Me
Ph2ICl
4k
a Isolated yield based on 1.
R1
R2Me2Si
P(O)Ph2
E
(R2Me2Si)2CuCNLi2
P(O)Ph2
CuLi
R1
R2Me2Si
EX
R1
P(O)Ph2
1
4
2
Br
EX = I2, NBS, NCS, PhSeBr, PhTeI,
Ph2ICl
Scheme 2
Synthesis 2006, No. 2, 231–236 © Thieme Stuttgart · New York

PAPER
Synthesis of b-Silyl Substituted Vinylphosphine Oxides
233
PdCl2(PPh3)2 (10 mol%)
P(O)Ph2
+
EtOCH2
Me3Si
P(O)Ph2
Ph
EtOCH2
Me3Si
CuI (10 mol%)
Ph
I
Et3N, MeCN
50 °C
4a
5
86%
Scheme 3
13C NMR: d = 169.72 (d, J = 6.2 Hz), 137.69, 135.14 (d, J = 102.0
Hz), 134.50, 131.98 (d, J = 3.0 Hz), 131.40 (d, J = 88.2 Hz), 131.26
(d, J = 9.9 Hz), 129.60, 129.03 (d, J = 12.2 Hz), 128.13, 71.79 (d,
J = 12.2 Hz), 66.52, 15.32, –1.96.
MS (EI): m/z (%) = 135 (75), 201 (14), 313 (100), 421 (27, [M+ +
1]).
Pd(OAc)2 (5 mol%)
dppp (5 mol%)
CO
P(O)Ph2
MeOCH2
Me3Si
P(O)Ph2
COOMe
MeOCH2
Me3Si
MeOH, Et3N
I
DMSO, ClCH2CH2Cl
6
4c
70 °C
73%
Anal. Calcd for C25H29O2PSi: C, 71.40; H, 6.95. Found: C, 71.50;
H, 6.83.
Scheme 4
3c
Oil.
and the applications of these products are now carried out
in our laboratory.
IR (film): 1486, 1437, 1243, 1200, 1117, 847 cm–1.
1H NMR: d = 7.75 (m, 4 H), 7.45 (m, 6 H), 7.31 (m, 2 H), 7.24 (m,
1 H), 7.08 (m, 2 H), 6.74 (d, J = 30.0 Hz), 0.22 (s, 9 H).
13C NMR: d = 170.96 (d, J = 7.6 Hz), 148.38 (d, J = 22.9 Hz),
136.71 (d, J = 90.8 Hz), 135.70 (d, J = 100.6 Hz), 131.89 (d,
J = 2.5 Hz), 131.53 (d, J = 9.4 Hz), 129.02 (d, J = 11.9 Hz), 128.44,
126.96, 126.30 (d, J = 1.4 Hz), –1.46.
1
All H NMR spectra were measured in CDCl3 and recorded on
Bruker Avance 400 (400 MHz) spectrometer with TMS as the inter-
nal standard. 13C NMR spectra were measured in CDCl3 and record-
ed on Bruker Avance 400 (100 MHz) spectrometer with TMS as the
internal standard. Chemical shifts are expressed in ppm and J values
are given in Hz. IR spectra were run on a Bruker vector 22 spec-
trometer. EIMS were determined with a HP5989B mass spectrom-
eter. Elemental analyses were performed on an EA-1110
instrument.
MS (EI): m/z (%) = 43 (100), 73 (77), 201 (11), 377 (5, [M+ + 1]).
Anal. Calcd for C23H25OPSi: C, 73.37; H, 6.69. Found: C, 73.51; H,
6.53.
Vinylphosphine Oxides 3a–g; General Procedure
3d
Oil.
CuCN (1 mmol, 90 mg) was introduced into a stirred solution of
organosilyllithium16 (2 mmol) in THF (5 mL) at 0 °C. After stirring
for 30 min, the temperature was lowered to –78 °C, and a solution
of the appropriate 1-alkynylphosphine oxide 1 (1 mmol) in THF (3
mL) was added slowly. The reaction mixture was allowed to warm
at –20 °C during several hours, followed by hydrolysis with sat. aq
NH4Cl (5 mL), and then extraction with Et2O (3 × 15 mL). The
combined Et2O layers were dried (MgSO4). After filtration and re-
moval of the solvent in vacuo, the crude product was purified with
flash chromatography (hexane–EtOAc, 2:1).
IR (film): 1436, 1248, 1193, 1115, 835 cm–1.
1H NMR: d = 7.72 (m, 4 H), 7.43 (m, 6 H), 6.42 (d, J = 30.0 Hz, 1
H), 2.62 (t, J = 6.4 Hz, 2 H), 1.19 (m, 4 H), 0.74 (t, J = 7.1 Hz, 3 H),
0.19 (s, 3 H), 0.07 (s, 6 H).
13C NMR: d = 174.05 (d, J = 6.0 Hz), 135.80 (d, J = 100.0 Hz),
131.31 (d, J = 2.8 Hz), 130.96 (d, J = 9.0 Hz), 129.86 (d, J = 91.0
Hz), 128.45 (d, J = 2.0 Hz), 34.74 (d, J = 12.0 Hz), 31.95 (d, J = 2.0
Hz), 23.12 (d, J = 6.0 Hz), 13.78, –1.22, –1.91.
3a
Oil.
MS (EI): m/z (%) = 73 (100), 201 (34), 283 (9), 311 (74), 357 (4,
[M+ + 1]).
IR (film): 1437, 1245, 1193, 1113, 839 cm–1.
Anal. Calcd for C21H29OPSi: C, 70.75; H, 8.20. Found: C, 70.62; H,
8.34.
1H NMR: d = 7.64 (m, 4 H), 7.37 (m, 6 H), 6.35 (d, J = 31.2 Hz, 1
H), 4.53 (d, J = 17.3 Hz, 2 H), 3.25 (q, J = 6.8 Hz, 2 H), 1.00 (t,
J = 6.8 Hz, 3 H), 0.13 (s, 6 H), 0.01 (s, 3 H).
3e
Oil.
13C NMR: d = 171.62 (d, J = 6.4 Hz), 134.97 (d, J = 101.0 Hz),
131.54, 130.86 (d, J = 2.0 Hz), 128.67 (d, J = 4.0 Hz), 128.55 (d,
J = 4.0 Hz), 71.97 (d, J = 12.0 Hz), 66.21 (d, J = 11.0 Hz), 15.03
(d, J = 2.2 Hz), –0.96, –1.73.
IR (film): 1588, 1483, 1248, 1194, 1112, 830 cm–1.
1H NMR: d = 7.69 (m, 4 H), 7.48 (m, 2 H), 7.39 (m, 6 H), 7.31 (m,
3 H), 6.48 (d, J = 30.4 Hz, 1 H), 2.64 (t, J = 6.6 Hz, 2 H), 1.11 (m,
4 H), 0.64 (t, J = 6.8 Hz, 3 H), 0.42 (s, 6 H).
MS (EI): m/z (%) = 73 (80), 84 (100), 201 (53), 358 (6, [M+]).
13C NMR: d = 172.07 (d, J = 5.8 Hz), 137.23, 135.89 (d, J = 100.0
Hz), 134.36, 132.18, 131.79 (d, J = 2.0 Hz), 131.30 (d, J = 11.0
Hz), 129.84, 128.97 (d, J = 11.5 Hz), 128.34, 34.35 (d, J = 12.1
Hz), 32.11 (d, J = 1.5 Hz), 23.33, 14.06, –2.32.
Anal. Calcd for C20H27O2PSi: C, 67.01; H, 7.59. Found: C, 67.13;
H, 7.46.
3b
Oil.
MS (EI): m/z (%) = 135 (60), 201 (33), 283 (4), 311 (100), 419 (6,
[M+ + 1]).
IR (film): 1437, 1249, 1193, 1115, 819 cm–1.
1H NMR: d = 7.63 (m, 4 H), 7.52 (m, 2 H), 7.36 (m, 6 H), 7.30 (m,
3 H), 6.39 (d, J = 29.6 Hz, 1 H), 4.61 (d, J = 15.6 Hz, 2 H), 3.19 (q,
J = 7.2 Hz, 2 H), 0.97 (t, J = 7.2 Hz, 3 H), 0.46 (s, 6 H).
Anal. Calcd for C26H31OPSi: C, 74.60; H, 7.46. Found: C, 74.49; H,
7.60.
Synthesis 2006, No. 2, 231–236 © Thieme Stuttgart · New York

234
X. Huang, L. Xu
PAPER
3f
Oil.
Anal. Calcd for C20H26IO2PSi: C, 49.59; H, 5.41. Found: C, 49.67;
H, 5.26.
IR (film): 1434, 1248, 1192, 1113, 831 cm–1.
4b
Oil.
1H NMR: d = 7.64 (m, 4 H), 7.53 (m, 2 H), 7.44 (m, 6 H), 7.34 (m,
3 H), 6.42 (d, J = 29.6 Hz, 1 H), 4.57 (s, 2 H), 3.06 (s, 3 H), 0.47 (s,
6 H).
13C NMR: d = 168.87 (d, J = 5.8 Hz), 137.04, 134.65 (d, J = 102.0
Hz), 134.05, 131.56 (d, J = 2.0 Hz), 131.45, 130.76 (d, J = 10.0
Hz), 129.22, 128.62 (d, J = 12.2 Hz), 127.75, 73.24 (d, J = 11.9
Hz), 58.27, –2.47.
IR (film): 1437, 1246, 1193, 1116, 836 cm–1.
1H NMR: d = 7.75 (m, 4 H), 7.43 (m, 6 H), 2.77 (s, 2 H), 1.15 (m, 4
H), 0.70 (t, J = 7.2 Hz, 3 H), 0.29 (s, 6 H), 0.14 (s, 3 H).
13C NMR: d = 176.13 (d, J = 10.0 Hz), 133.92 (d, J = 105.7 Hz),
133.86 (d, J = 102.0 Hz), 132.44 (d, J = 4.0 Hz), 132.34 (d, J = 4.0
Hz), 131.91, 128.36 (d, J = 12.0 Hz), 39.03 (d, J = 9.0 Hz), 32.16,
22.74, 13.80, –0.37, –0.48.
MS (EI): m/z (%) = 135 (63), 201 (21), 313 (100), 391 (14), 407 (2,
[M+ + 1]).
MS (EI): m/z (%) = 73 (100), 201 (40), 355 (23), 483 (3, [M+ + 1]).
Anal. Calcd for C24H27O2PSi: C, 70.91; H, 6.69. Found: C, 70.79;
H, 6.80.
Anal. Calcd for C21H28IO2PSi: C, 52.28; H, 5.85. Found: C, 52.20;
H, 5.96.
3g
Oil.
4c
Oil.
IR (film): 1437, 1246, 1192, 1114, 845 cm–1.
IR (film): 1437, 1244, 1190, 1098, 835 cm–1.
1H NMR: d = 7.75 (m, 4 H), 7.50 (m, 6 H), 6.47 (d, J = 30.0 Hz, 1
H), 4.62 (s, 2 H), 3.20 (s, 3 H), 0.21 (s, 9 H).
1H NMR: d = 7.76 (m, 4 H), 7.52 (m, 2 H), 7.44 (m, 4 H), 4.42 (s, 2
H), 2.94 (s, 3 H), 0.35 (s, 9 H). 13C NMR: d = 170.78, 132.57 (d,
J = 107.1 Hz), 132.19 (d, J = 9.4 Hz), 131.94 (d, J = 2.9 Hz),
128.18 (d, J = 12.0 Hz), 107.76 (d, J = 75.7 Hz), 73.84 (d, J = 10.8
Hz), 57.32, –0.19.
13C NMR: d = 170.73 (d, J = 6.7 Hz), 134.22 (d, J = 101.1 Hz),
131.49 (d, J = 2.7 Hz), 130.78 (d, J = 9.2 Hz), 129.52 (d, J = 85.7
Hz), 128.54 (d, J = 11.8 Hz), 73.39 (d, J = 12.8 Hz), 58.26, –1.17.
MS (EI): m/z (%) = 73 (22), 201 (10), 313 (30), 329 (100), 344 (28,
MS (EI): m/z (%) = 73 (37), 201 (18), 327 (42), 343 (3), 439 (11),
[M+]).
455 (100), 471 (3, [M+ + 1]).
Anal. Calcd for C19H25O2PSi: C, 66.25; H, 7.32. Found: C, 66.41;
H, 7.20.
Anal. Calcd for C19H24IO2PSi: C, 48.52; H, 5.14. Found: C, 48.41;
H, 5.29.
Vinylphosphine Oxides 4a–k; General Procedure
4d
CuCN (90 mg, 1 mmol) was introduced into a stirred solution of or-
ganosilyllithium (2 mmol) in THF (5 mL) at 0 °C. After stirring for
30 min, the mixture was cooled to –78 °C, and a solution of appro-
priate 1-alkynylphosphine oxide (1 mmol) in THF (3 mL) was add-
ed slowly and the reaction mixture was allowed to warm to –20 °C
during several hours. The mixture was cooled to –78 °C again and
the respective electrophile {in the cases of 4a, 4b, 4c and 4d, I2 (508
mg, 2 mmol) in THF (3 mL); in the cases of 4e and 4f, NBS and
NCS (356 mg and 267 mg, respectively, 2 mmol); in the case of 4g,
phenylselenyl bromide (472 mg, 2 mmol) in THF (3 mL); in the
case of 4h, phenyltelluryl iodine [2 mmol: prepared by reaction of
diphenyl ditelluride (408 mg, 1 mmol) with iodine (254 mg, 2
mmol) in THF (3 mL) for 1 h at r.t.]; in the cases of 4i and 4j, allyl
bromide (242 mg, 2 mmol) in THF (3 mL)} was added dropwise [in
the case of 4k, diphenyliodonium chloride (640 mg, 2 mmol) was
added directly]. The reaction mixture was allowed to warm to r.t.
and quenched with aq NH4Cl (5 mL), then extracted with Et2O (3 ×
15 mL), and dried (MgSO4). After filtration and removal of the sol-
vent in vacuo, the crude product was purified with flash chromatog-
raphy (hexane–EtOAc, 1:1).
Oil.
IR (film): 1484, 1246, 1196, 1115, 839 cm–1.
1H NMR: d = 7.56 (m, 4 H), 7.38 (m, 2 H), 7.27 (m, 4 H), 6.85 (m,
3 H), 6.56 (m, 2 H), 0.26 (s, 5 H), 0.18 (s, 4 H).
13C NMR: d = 173.91, 143.45 (d, J = 9.2 Hz), 133.46 (d, J = 107.0
Hz), 132.33 (d, J = 9.0 Hz), 131.79, 131.76 (d, J = 3.1 Hz), 128.55
(d, J = 11.0 Hz), 127.90 (d, J = 3.0 Hz), 126.58, 126.43 (d, J = 13.2
Hz), –0.49.
MS (EI): m/z (%) = 73 (85), 178 (100), 201 (55), 375 (93), 503 (2,
[M+ + 1]).
Anal. Calcd for C23H24IOPSi: C, 54.99; H, 4.82. Found: C, 54.86;
H, 4.96.
4e
Oil.
IR (film): 1437, 1245, 1196, 1094, 838 cm–1.
1H NMR: d = 7.79 (m, 4 H), 7.53 (m, 2 H), 7.45 (m, 4 H), 4.61 (d,
J = 18.0 Hz, 2 H), 3.20 (q, J = 7.2 Hz, 2 H), 0.99 (t, J = 7.2 Hz, 3
H), 0.32 (s, 6 H), 0.12 (s, 3 H).
13C NMR: d = 165.59, 132.70 (d, J = 108.0 Hz), 132.37 (d, J = 10.0
Hz), 132.15 (d, J = 2.0 Hz), 131.32 (d, J = 10.0 Hz), 128.44 (d,
J = 4.0 Hz), 70.33 (d, J = 15.0 Hz), 65.63 (d, J = 25.0 Hz), 15.17
(d, J = 5.0 Hz), –1.25, –1.90.
4a
Oil.
IR (film): 1437, 1245, 1192, 1115, 839 cm–1.
1H NMR: d = 7.77 (m, 4 H), 7.51 (m, 2 H), 7.43 (m, 4 H), 4.42 (d,
J = 27.2 Hz, 2 H), 3.05 (q, J = 6.8 Hz, 2 H), 0.93 (t, J = 6.8 Hz, 3
H), 0.35 (s, 6 H), 0.18 (s, 3 H).
13C NMR: d = 173.15, 133.44 (d, J = 101.0 Hz), 132.46 (d, J = 9.4
Hz), 132.11 (d, J = 2.3 Hz), 128.39 (d, J = 4.2 Hz), 128.27 (d,
J = 3.2 Hz), 72.45 (d, J = 10.5 Hz), 65.59 (d, J = 24.0 Hz), 15.07
(d, J = 5.6 Hz), –0.55, –0.83.
MS (EI): m/z (%) = 73 (100), 201 (29), 357 (5), 438 (2, [M+ + 1]).
Anal. Calcd for C20H26BrO2PSi: C, 54.92; H, 5.99. Found: C, 54.80;
H, 6.08.
4f
Oil.
MS (EI): m/z (%) = 73 (100), 201 (16), 357 (9), 485 (2, [M+ + 1]).
IR (film): 1434, 1251, 1198, 1114, 817 cm–1.
Synthesis 2006, No. 2, 231–236 © Thieme Stuttgart · New York

PAPER
Synthesis of b-Silyl Substituted Vinylphosphine Oxides
235
1H NMR: d = 7.77 (m, 4 H), 7.54 (m, 4 H), 7.44 (m, 4 H), 7.35 (m,
3 H), 2.92 (t, J = 7.6 Hz, 2 H), 1.33 (m, 2 H), 1.20 (m, 2 H), 0.75 (t,
J = 7.6 Hz, 3 H), 0.57 (s, 6 H).
13C NMR: d = 163.82 (d, J = 5.0 Hz), 137.82, 134.37, 133.02 (d,
J = 107.0 Hz), 132.56, 132.47, 132.42 (d, J = 3.0 Hz), 129.63,
128.80 (d, J = 13.0 Hz), 128.18 (d, J = 2.0 Hz), 37.02, 33.96 (d,
J = 7.0 Hz), 23.20, 14.09, –1.15.
IR (film): 1437, 1248, 1180, 1110, 817, 727 cm–1.
1H NMR: d = 7.56 (m, 6 H), 7.37 (m, 2 H), 7.30 (m, 7 H), 5.11 (m,
1 H), 4.63 (d, J = 10.4 Hz, 1 H), 4.40 (d, J = 17.2 Hz, 1 H), 4.27 (s,
2 H), 2.83 (d, J = 4.4 Hz, 2 H), 2.77 (s, 3 H), 0.42 (s, 6 H).
13C NMR: d = 157.62, 145.19 (d, J = 80.0 Hz), 138.92, 134.40,
134.19 (d, J = 98.6 Hz), 133.90, 133.43, 131.95 (d, J = 10.0 Hz),
131.38 (d, J = 3.0 Hz), 128.98, 128.00 (d, J = 11.0 Hz), 117.44,
73.30 (d, J = 15.0 Hz), 57.69, 38.95 (d, J = 18.0 Hz), –0.81.
MS (EI): m/z (%) = 135 (67), 201 (38), 317 (3), 345 (100), 417 (8),
453 (3, [M+ + 1]).
MS (EI): m/z (%) = 135 (100), 201 (63), 353 (89), 447 (2, [M+ + 1]).
Anal. Calcd for C26H30ClOPSi: C, 68.93; H, 6.67.Found: C, 68.80;
H, 6.81.
Anal. Calcd for C27H31O2PSi: C, 72.61; H, 7.00. Found: C, 72.74;
H, 6.88.
4g
Oil.
4k
Oil.
IR (film): 1437, 1246, 1189, 1112, 841 cm–1.
IR (film): 1437, 1256, 1196, 1112, 836 cm–1.
1H NMR: d = 7.82 (m, 4 H), 7.53 (m, 6 H), 7.39 (m, 5 H), 4.23 (s, 2
H), 3.24 (s, 3 H), 0.26 (s, 9 H).
13C NMR: d = 168.26, 133.11 (d, J = 102.2 Hz), 131.34 (d, J = 4.6
Hz), 130.86, 130.47 (d, J = 11.2 Hz), 130.05, 129.78 (d, J = 12.2
Hz), 129.44 (d, J = 20.2 Hz), 129.09 (d, J = 7.6 Hz), 122.38 (d,
J = 13.3 Hz), 70.45 (d, J = 11.6 Hz), 57.59, –1.09.
1H NMR: d = 7.59 (m, 4 H), 7.23 (m, 2 H), 7.12 (m, 4 H), 6.94 (m,
3 H), 6.80 (m, 2 H), 2.87 (t, J = 7.6 Hz, 2 H), 1.18 (m, 4 H), 0.73 (t,
J = 7.5 Hz, 3 H), 0.25 (s, 7 H), 0.12 (s, 2 H).
13C NMR: d = 184.16 (d, J = 2.0 Hz), 134.48, 133.45 (d, J = 21.6
Hz), 132.08 (d, J = 9.0 Hz), 131.06 (d, J = 3.0 Hz), 130.97 (d,
J = 102.0 Hz), 129.16, 128.58 (d, J = 11.0 Hz), 127.53 (d, J = 12.0
Hz), 125.87, 38.23 (d, J = 9.0 Hz), 31.82, 23.14, 13.78, –1.32,
–1.86.
MS (EI): m/z (%) = 73 (31), 201 (43), 405 (100), 421 (2, [M+ + 1]).
MS (EI): m/z (%) = 73 (100), 201 (21), 355 (51), 512 (5, [M+ + 1]).
Anal. Calcd for C25H29O2PSi: C, 71.40; H, 6.95. Found: C, 71.29;
H, 7.01.
Anal. Calcd for C27H33OPSeSi: C, 63.39; H, 6.50. Found: C, 63.29;
H, 6.61.
Sonogashira Cross-Coupling Reaction; (E)-3-Ethoxy-1-(2-
phenylethynyl)-2-(trimethylsilyl)prop-1-enyl(diphenyl)phos-
phine Oxide (5)
4h
Oil.
A mixture of the a-iodovinylphosphine oxide 4a (484 mg, 1 mmol),
phenylacetylene (204 mg, 2 mmol, 2.0 equiv), Pd(PPh3)2Cl2 (70 mg,
10 mol%), CuI (20 mg, 10 mol%), and Et3N (0.14 mL, 1 mmol, 1.0
equiv) in MeCN (5 mL) was stirred at 50 °C for about 8 h. After the
completion of the reaction, the mixture was washed with NH4Cl,
and filtered through a Celite pad. The organic layer was extracted
with EtOAc, and dried (MgSO4). The solvent was evaporated and
the residue purified by TLC or flash chromatography to afford the
product 5 as a pale yellow oil; yield: 392 mg (86%).
IR (film): 1436, 1203, 1117, 835 cm–1.
1H NMR: d = 7.60 (m, 4 H), 7.29 (m, 2 H), 7.15 (m, 4 H), 7.05 (m,
3 H), 6.98 (m, 2 H), 2.91 (t, J = 6.8 Hz, 2 H), 1.16 (m, 4 H), 0.71 (t,
J = 6.8 Hz, 3 H), 0.17 (s, 6 H), 0.09 (s, 3 H).
13C NMR: d = 178.31 (d, J = 3.2 Hz), 136.82 (d, J = 7.0 Hz),
134.60 (d, J = 104.0 Hz), 131.36 (d, J = 8.9 Hz), 130.70 (d, J = 2.0
Hz), 129.23 (d, J = 11.0 Hz), 127.62, 127.46, 126.50 (d, J = 10.5
Hz), 124.21, 39.32 (d, J = 13.0 Hz), 34.61, 22.85, 14.02, –1.41,
–2.09.
IR (film): 2191, 1438, 1245, 1189, 1116, 845 cm–1.
1H NMR: d = 7.80 (m, 4 H), 7.54 (m, 2 H), 7.45 (m, 4 H), 7.19 (m,
3 H), 6.82 (m, 2 H), 4.64 (d, J = 2.0 Hz, 2 H), 3.14 (q, J = 6.8 Hz, 2
H), 0.95 (t, J = 6.8 Hz, 3 H), 0.35 (s, 9 H).
13C NMR: d = 171.89, 133.83 (d, J = 103.0 Hz), 131.93 (d, J = 9.0
Hz), 131.72 (d, J = 2.0 Hz), 130.96 (d, J = 2.0 Hz), 129.00, 128.60,
128.33, 128.21, 122.65 (d, J = 3.0 Hz), 89.94, 89.77, 70.20 (d,
J = 10.0 Hz), 65.63, 15.04, –0.59.
MS (EI): m/z (%) = 73 (100), 201 (24), 355 (16), 561 (2, [M+ + 1]).
Anal. Calcd for C27H33OPSiTe: C, 57.89; H, 5.94. Found: C, 57.98;
H, 5.80.
4i
Oil.
IR (film): 1437, 1251, 1186, 1109, 838 cm–1.
MS: m/z (%) = 73 (100), 201 (32), 257 (2), 385 (2), 429 (63), 458
1H NMR: d = 7.54 (m, 4 H), 7.23 (m, 6 H), 5.27 (m, 1 H), 4.67 (d,
J = 10.8 Hz, 1 H), 4.56 (d, J = 10.8 Hz, 1 H), 2.91 (t, J = 7.8 Hz, 2
H), 2.35 (m, 2 H), 0.95 (m, 4 H), 0.54 (t, J = 7.6 Hz, 3 H), 0.13 (s,
6 H), 0.03 (s, 3 H).
(7, [M+]).
Anal. Calcd for C28H31O2PSi: C, 73.33; H, 6.81. Found: C, 73.20;
H, 6.96.
13C NMR: d = 164.66 (d, J = 18.0 Hz), 139.89 (d, J = 83.2 Hz),
135.55 (d, J = 5.0 Hz), 135.30 (d, J = 96.7 Hz), 131.89 (d, J = 9.0
Hz), 131.11 (d, J = 4.0 Hz), 128.02 (d, J = 12.0 Hz), 117.32 (d,
J = 9.0 Hz), 40.38 (d, J = 17.0 Hz), 38.82 (d, J = 16.8 Hz), 31.98
(d, J = 11.0 Hz), 22.95, 13.70, –1.23, –1.62.
Carbomethoxylation Reaction; Methyl (E)-2-(Diphenylphos-
phoryl)-4-methoxy-3-(trimethylsilyl)but-2-enoate (6)
A mixture of 4c (470 mg, 1 mmol), Pd(OAc)2 (12 mg, 5 mol%), 1,3-
bis(dipheny1phosphino) propane (dppp, 21 mg, 5 mol%), Et3N
(0.28 mL, 2 mmol), methanol (2 mL), 1,2-dichloroethane (2 mL),
and DMSO (5 mL) was heated at 70 °C under an atmosphere of CO
for 6 h. The cooled reaction mixture was then diluted with CHCl3,
washed with H2O, 10% aq HCl, 10% aq NaHCO3, and brine, and
dried (MgSO4). The solvent was evaporated and the residue purified
by TLC or flash chromatography to afford the product 6 as an oil;
yield: 294 mg (73%).
MS (EI): m/z (%) = 73 (100), 201 (12), 323 (14), 397 (16, [M+ + 1]).
Anal. Calcd for C24H33OPSi: C, 72.69; H, 8.39. Found: C, 72.81; H,
8.27.
4j
Oil.
IR (film): 1720, 1437, 1219, 1192, 1098, 843 cm–1.
Synthesis 2006, No. 2, 231–236 © Thieme Stuttgart · New York

236
X. Huang, L. Xu
PAPER
(9) (a) Bardels, B.; Clayden, J.; Martin, C. G.; Neslson, A.;
1H NMR: d = 7.74 (m, 4 H), 7.53 (m, 6 H), 4.36 (s, 2 H), 3.87 (s, 3
H), 3.18 (s, 3 H), 0.24 (s, 9 H).
13C NMR: d = 170.3, 164.67, 142.65 (d, J = 118.4 Hz), 131.83,
131.33 (d, J = 3.1 Hz), 130.15 (d, J = 5.7 Hz), 129.49 (d, J = 4.9
Hz), 68.36 (d, J = 11.3 Hz), 57.59, 52.23 (d, J = 2.6 Hz), –0.96.
Russel, M. G.; Warren, S. J. Chem. Soc., Perkin Trans.1
1999, 1807. (b) Clayden, J.; Neslson, A.; Warren, S.
Tetrahedron Lett. 1997, 38, 3471.
(10) (a) Brandi, A.; Cannavò, P.; Pietrusiewicz, K. M.; Zablocka,
M.; Wieczorek, M. J. Org. Chem. 1989, 54, 3073.
(b) Brandi, A.; Cicchi, S.; Goti, A.; Pietrusiewicz, K. M.;
Zablocka, M.; Wieczorek, M. J. Org. Chem. 1991, 56, 4383.
(11) Nicolaou, K. C.; Maligres, P.; Shin, J.; de Leon, E.; Rideout,
D. J. Am. Chem. Soc. 1990, 112, 7825.
MS: m/z (%) = 73 (31), 201 (32), 371 (56), 387 (100), 402 (7, [M+]).
Anal. Calcd for C21H27O4PSi: C, 62.67; H, 6.76. Found: C, 62.53;
H, 6.96.
(12) (a) Fleming, I.; Roessler, F. J. Chem. Soc., Chem. Commun.
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J. Synthesis 2000, 1223.
Acknowledgment
We are grateful to the National Natural Science Foundation of
China (Project No. 20272050, 20332060) for financial support.
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Synthesis 2006, No. 2, 231–236 © Thieme Stuttgart · New York