Some synthetic applications of vinylphosphane oxides

Article abstract of DOI:10.1016/j.tet.2010.10.016

Vinylphosphane oxides have been used as Michael acceptors for the diastereoselective synthesis of anti α-functionalized-β-silylated phosphane oxides and β-stannyl-, β-phenylthio- or β-phosphanyl phosphane oxides. Although the utility of these substrates as dipolarophiles was more limited, we have obtained a mixture of 3- and 4-phosphanylpyrazoles in which the latter is the major regioisomer, by 1,3-cycloaddition with N-phenylsydnone. Moreover, vinylphosphane oxides reacted with aldehydes in the presence of LDA by a Baylis-Hillman type reaction, leading to (E)-β-hydroxyphosphane oxides, which were readily converted in allenes. It is noteworthy that the application of this methodology to silylated substrates has permitted us to synthesize an interesting and more versatile silylallene.

Full text of DOI:10.1016/j.tet.2010.10.016

Tetrahedron 66 (2010) 9610e9619
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Some synthetic applications of vinylphosphane oxides
*
Ana M. Gonzalez-Nogal , Purificacion Cuadrado, Maria A. Sarmentero
Departamento de Quimica Organica, Facultad de Ciencias and Centro de Innovacion en Quimica y Materiales Avanzados(CINQUIMA), Universidad de Valladolid,
Dr. Mergelina s/n, 47011 Valladolid, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 August 2010
Received in revised form 27 September 2010
Accepted 8 October 2010
Available online 14 October 2010
Vinylphosphane oxides have been used as Michael acceptors for the diastereoselective synthesis of anti
a-functionalized-b-silylated phosphane oxides and b-stannyl-, b-phenylthio- or b-phosphanyl phos-
phane oxides. Although the utility of these substrates as dipolarophiles was more limited, we have
obtained a mixture of 3- and 4-phosphanylpyrazoles in which the latter is the major regioisomer, by 1,3-
cycloaddition with N-phenylsydnone. Moreover, vinylphosphane oxides reacted with aldehydes in the
presence of LDA by a BayliseHillman type reaction, leading to (E)-b-hydroxyphosphane oxides, which
Keywords:
were readily converted in allenes. It is noteworthy that the application of this methodology to silylated
substrates has permitted us to synthesize an interesting and more versatile silylallene.
Ó 2010 Elsevier Ltd. All rights reserved.
Phosphane oxides
Michael additions
1,3-Dipolar cycloadditions
Silylallenes
1. Introduction
respectively.7 We have prepared for the first time, 3- and 4-phos-
phanyl-N-phenylpyrazoles by reaction of vinylphosphane oxides
Organophosphorus compounds are of great chemical and bi-
ological interest.1 They have also found much utility as ligands in
asymmetric catalysis.2 These hemilabile ligands have also en-
countered success with applications in small-molecule activation,
small-molecule sensing and stabilization of transition complexes.3
Owing to the multiple ways in which they can be employed, the
synthesis of small molecules containing phosphorus has garnered
significant attention.4 More importantly, the ability to generate
phosphorus compounds with chiral centers at or near phosphorus
in an asymmetric fashion is particularly attractive.
Previously, we have synthesised vinylphosphane oxides by
regio- and stereo-specific cleavage of epoxysilanes5 with lithium
diphenylphosphide. In this paper, we describe some synthetic ap-
plications of vinylphosphane oxides as Michael acceptors, 1,3-
dipolarophiles and precursors in the synthesis of allenes.
with N-phenylsydnone.
On the other hand, we have synthesised silylallenes through
a methodology,8 which involves HornereWittig elimination of
silylated b-hydroxyalkenylphosphane oxides obtained, in turn, by
reaction of silyl alkenylphosphane oxides with aldehydes in the
presence of lithium amides.
2. Results and discussion
We have studied the behavior of stereodefined vinylphosphane
oxides, which were obtained by us previously,5 as electrophilic
acceptors toward a variety of heteroatomic nucleophiles, such as
silyl- and stannyl-metals, sulfur, and phosphorus compounds.
2.1. Reaction of vinylphosphane oxides with silylcuprates and
silyllithium reagents
The use of vinylphosphane oxides as Michael acceptors has been
previously proved.6 We have studied the conjugate addition of
heteroatomic nucleophiles at stereodefined vinylphosphane oxides
attaining a diastereospecific useful route to synthesise highly func-
tionalized phosphane oxides containing two or three chiral centers.
The reactivity of these substrates in 1,3-dipolar cycloadditions is
Although the reaction of vinylphosphane oxides with lithium
dialkylcuprates6b,c,9 hasbeenpreviouslystudied,thebehaviorof these
substrates with lithium silylcuprates has received little attention.
Fleming et al.10 described the addition of lithium bis-dimethylphe-
nylsilyl and bis-trimethylsilylcuprate at E-1-propenyldiphenylphos-
phane oxide to give a mixture of two and four diastereoisomers of the
low and has been practically limited to
b-unsubstituted vinyl-
phosphane oxides. They react with nitrile oxides or nitrones to give
mixtures of 4- and 5-phosphanyl-2-isoxazolines or isoxazolidines,
corresponding
Warren et al.6b,c prepared diastereoselectively
ides by reaction of -oxygenated chiral vinylphosphane oxides with
lithium bis-dimethylphenylsilylcuprate.
b-silylated alkylphosphane oxide, respectively. Later,
b-silyl phosphane ox-
g
* Corresponding author. Tel.: þ34983423213; fax: þ34983423013; e-mail address:
agn@qo.uva.es (A.M. Gonzalez-Nogal).
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.10.016

A.M. Gonzalez-Nogal et al. / Tetrahedron 66 (2010) 9610e9619
9611
R1
R3Si
R1
R3Si
The known stability and versatility of the silyl groups confer on
E
E
theses phosphane oxides an additional interest. Therefore, we decided
to study the behavior of vinylphosphane oxides with different sub-
stitution patterns toward higher-order lithium silylcuprates. We have
usedmixed cuprates of carbon and silicondbutylsilylcupratesdwhich
transfer selectively the silyl group but they are more advantageous
than the bis-silylcuprates because they cheapen the synthesis and
simplify the isolation process. Moreover, with the aim of increasing the
functionalization of theses compounds we have tried to capture the
intermediates of the silylcupration with various electrophiles such as
allyl bromide, ethyl chloroformate, benzoyl chloride, iodine, and some
aldehydes.
The vinylphosphane oxides 1aed reacted with lithium butyl
(dimethylphenylsilyl) and butyl(tert-butyldiphenylsilyl)cuprate to
give a phosphorylated intermediate A, which afforded the b-sily-
lated phosphane oxides 2aef by hydrolysis. Moreover, this in-
termediate A could be captured ‘in situ’ by ethyl chloroformate and
allyl bromide yielding 3aed. Nevertheless, A was shown to be
unreactive toward other electrophiles, such as benzaldehyde, iso-
butyraldehyde, benzoyl chloride, and iodine.
PPh2
PPh2
O
O
R1
R1
H
H
Ph2P
E
H
Ph2P
E
H
φ = 180º
φ = 60º
SiR3
SiR3
O
O
syn
anti
Fig. 1. Newman projections of syn and anti isomers.
the minor syn-3b the two hydrogen atoms are in close spatial
proximity, whereas in the major anti-3b they are far away in space.
The only exception to this outcome is that observed in the re-
action of 1c with the tert-butyldiphenylsilylcuprate. Instead of the
expected addition product, we isolated the E-vinyldisilane 4a. This
anomalous behavior could be due to the rearrangement of tert-
butyldiphenylsilyl group, which has more migratory aptitude than
the dimethylphenylsilyl group,11 from the gem-disilylated carbon to
The a-functionalized b-silylated phosphane oxides 3a,b,d were
isolated as a mixture of syn-anti diastereomers, in which the anti
isomer was the major product. The results are collected in Scheme 1
and Table 1.
the
B, giving the intermediate C in which the quasi-carbanion is sta-
bilized by the -silyl group. The E1CB elimination of the phosphanyl
group afforded the E-disilylalkene 4a (Scheme 2).
a-C. This would decrease the steric impedance of intermediate
a
R2 Si
(Cu)
R2 Si
E
R1
R2 Si(Bu)CNCuLi2
3
3
E
3
PhMe2Si
tBuPh2Si(Bu)CNCuLi2
PPh2
PhMe2Si
R1
PPh2
O
R1
PPh2
O
PPh2
A
SiPh2But
O
1c
2a–f
3a-d
1a–d
4a (62%)
O
E1CB
Scheme 1.
(Cu)
δ
PhMe2Si
SiPh2But
tBuPh2Si
(Cu)
Table 1
Silylcupration of vinylphosphane oxides and reaction with electrophiles
δ
PPh2
PhMe2Si
PPh2
O
C
Vinylphosphane oxide Silylcuprate Electrophile
Products
O
B
1a; R1¼Me (Z)
R2 ¼Me2Ph Hþ
2a (74%)
2b (70%)
2c (67%)
2d (59%)
2e (52%)
2f (43%)
3
Scheme 2.
1a
R2 ¼Ph2tBu Hþ
3
1b; R1¼Bu (Z)
R2 ¼Me2Ph Hþ
3
1c; R1¼SiMe2Ph (E)
R2 ¼Me2Ph Hþ
Given the limited reactivity of the silylcuprate intermediate A
toward electrophiles, we tested the behavior of these vinyl-
phosphane oxides with silyllithium reagents with the aim of in-
creasing the reactivity of the resulting silyllithium intermediate D
with electrophiles, which were shown to be unreactive toward the
silylcuprate intermediate A resulting from the silylcupration.
We have studied the reaction of the vinylphosphane oxides 1a,1c,
1e, and 1f with dimethylphenyl- and tert-butyldiphenylsilyllithium
reagents and capture of the corresponding intermediate D with allyl
bromide, ethyl chloroformiate, benzoyl chloride, benzaldehyde, and
iodine. Unfortunately, the lithium intermediate was shown to be
unreactive toward the electrophiles tested. In all cases, the product
resulting from its hydrolysis was isolated. The yield for 2a, 2b, and 2d
was worse than that obtained by silylcupration (Scheme 3).
3
1d; R1¼Ph (E)
R2 ¼Me2Ph Hþ
3
1d
1a
1a
R2 ¼Ph2tBu Hþ
3
R2 ¼Me2Ph ClCO2Et
anti-3a (36%)þsyn-3a (11%)
3
R2 ¼Me2Ph BrCH2CH]CH2 anti-3b (39%)þsyn-3b
3
(12%)
1c
1d
R2 ¼Me2Ph BrCH2CH]CH2 3c (50%)
3
R2 ¼Me2Ph BrCH2CH]CH2 anti-3d (35%)þsyn-3d
3
(10%)
The syn or anti silylcuprate addition of Z or E vinylphosphane
oxides afforded two possible diastereoisomers in a conformation
stabilized by SieO interactions. Probably the anti isomer is, in all
cases, the major product because it is the more stable. In the anti
isomer the most bulky groups are more distant as can be seen in the
Newman projections (Fig. 1).
When the
b-silyl vinylphosphane oxide 1c reacted with tert-
butyldiphenylsilyllithium gave, as occurred in its reaction with the
The configurational assignation of the syn and anti isomers of
3aed was possible by 1H NMR spectroscopy and NOESY experi-
ments. The coupling constants between vic-protons are those
tert-butyldiphenylsilylcuprate, the vinylsilane 4a. On the other
hand, the treatment of the b-phenyl vinylphosphane oxide 1d with
dimethylphenyl- and tert-butyldiphenylsilyllithium also afforded
the vinylsilanes 4b and 4c, respectively (Scheme 4).
Probably in this case, the 1,2-rearrangement of the silyl group is
favored due to the major carbanionic character of the lithiated in-
termediate regarding the cuprate intermediate and the formation
of a new carbanion stabilized by the phenyl group (Scheme 5).
This outcome provides a simple and direct access to vinylsilanes
from vinylphosphane oxides.
expected according to the dihedral angle,
4
¼60ꢀ in the syn isomer
and
4
¼180ꢀ in the anti isomer. Thus, the syn-3a, which in the que-
lated conformation has a
4
¼60ꢀ showed a JH/H¼1.7 Hz, while the
anti-3a isomer with
4
¼180ꢀ has a JH/H¼12.4 Hz. Moreover, the minor
diastereoisomer of 3b showed a positive NOE between the protons
attached to the chiral carbons while no NOE effect was observed
between these hydrogens in the major product. It confirms that in

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A.M. Gonzalez-Nogal et al. / Tetrahedron 66 (2010) 9610e9619
R23Si
R1
R23Si
R1
H
Ph
PhMe2Si
R1
Li
R23SiLi
PPh2
1. E
1. LDA, 0 ºC
2. E or H3O
2. H3O
SiMe2Ph
4b (81%)
Ph
PPh2
PPh2
O
PPh2
D
O
O
O
2d
1a; R1 = Me (Z)
R23 = Me2Ph
R23 = Ph2But
Scheme 7.
2a (49%)
2b (63%)
2d (57%)
2g (65%)
electrophile. The reaction occurred with total diastereoselectivity12
when iodine, benzaldehyde, and isobutyraldehyde were used,
while mixtures of the two possible diastereoisomers were obtained
in the reactions with allyl bromide and benzoyl chloride. The mixture
of syn-3b and anti-3b was separated by chromatography and their
configurations were assigned as previously mentioned. Although the
two diastereoisomers of 3e were impossible to separate, the config-
urational determination of the synandantiisomerwas possible by 1H
NMR spectroscopy and NOESY experiments. The coupling constants
JH/H¼2.5 Hz and JH/H¼11.7 Hz, together with the presence or absence
of the NOE effect between these protons, permit us the unequivocal
assignation of syn-3e and anti-3e, respectively (Fig. 2). Probably, the
exclusive formation of the anti diastereoisomer when iodine was
utilised as an electrophile would be due to the steric requirement of
the bulky iodine atom. In the anti isomer the iodine atom is anti tothe
silyl group in the quelated Newman projection (Fig. 2).
1a
1c; R1 = SiMe2Ph (E)
1e; R1 = H
1f; R1 = SiMe3 (E)
R23 = Me2Ph
R23 = Me2Ph
R23 = Me2Ph
Scheme 3.
2h (45%)
R1
R1
1. R3SiLi
2. aq. NH4Cl
SiR3
PPh2
O
1c; R1 = SiMe2Ph
4a (63%); R3 = Ph2But
1d; R1 = Ph
4b ( 77%); R3 = Me2Ph
4c (68%); R3 = Ph2But
1d
Me
Me
Me
PhOC
PhOC
H
H
H
I
H
H
Scheme 4.
ΝΟΕ
PhMe2Si
H
SiMe2Ph
SiMe2Ph
PPh2
Ph2P
Ph2P
O
O
O
R3Si
Ph
Li
Li
SiR3
PPh2
Ph
E1CB
R3SiLi
δ
δ
φ = 60º
φ = 180º
J = 2.5 Hz
J = 11.7 Hz
Ph
PPh2
SiR3
Ph
PPh2
anti-3e
syn-3e
O
anti-3f
D
O
O
4b,c
1d
Fig. 2. Newman projections of syn-3e and anti-3e.
Scheme 5.
When benzaldehyde and isobutyraldehyde were used as elec-
trophiles two new chiral carbons were created and, consequently,
four diastereoisomers could be obtained. Nevertheless, the reaction
took place with total diastereoselectivity to give 3g and 3h as sole
Owing to the scarce or null reactivity of the intermediates A and
D, resulting from the silylcupration or silyllithiation toward elec-
trophiles we have opted for an alternative methodology used by
a-deprotonation of the b-silylated
phosphane oxides, resulting from hydrolysis of the silylcuprate
Fleming,10 consisting of the
isomers. The stereochemical assignation of the b-hydroxyphosphane
oxides 3g and 3h was difficult. Intramolecular hydrogen bond be-
tween the hydroxy and phosphanyl groups was confirmed by com-
parative IR spectroscopy of the compounds in the solid state and at
intermediate A and subsequent capture with electrophiles.
The results depend on the nature of the group attached at
b-po-
sition. The lithiated intermediate of the -methyl phosphane oxide
b
different dilutions in CH2Cl2. The frequency and shape of the
n OH
2a was shown to be reactive toward electrophiles such as allyl bro-
mide, benzoyl chloride, iodine, benzaldehyde, and isobutyraldehyde
(Scheme 6).
band did not change. Starting from this fact and on the assumption
that the major products in the reactions of the lithiated phosphane
oxide 2a with all electrophiles tested were those that have the anti
relationship between the silyl group and the electrophile, we
assigned the relative configurations in the C-2 and C-3. Therefore, 3g
and 3h could have one of the two structures collected in Fig. 3.
PhMe2Si
Me
E
PhMe2Si
Me
1. LDA, 0º C
2. E
PPh2
O
PPh2
Me
H
Me
H
O
2a
R
H
anti-3b (38%)
syn-3b (20%)
E = BrCH2CH=CH2
E = ClCOPh
E = CH2CH=CH2
SiMe2Ph
3
SiMe2Ph
H
3
R
H
1
H
2
2
1
O
PPh2
O
PPh2
anti-3e (41%)
syn-3e (15%)
E = COPh
H
O
H
O
anti-3f (45%); E = I
E = I2
II
I
3g; R = Ph
3h; R = iPr
3g (44%); E = CH(OH)Ph
3h (53%); E = CH(OH)iPr
E = PhCHO
E = (CH3)2CHCHO
Fig. 3. Possible structures for 3g and 3h.
Scheme 6.
The spatialarrangementof thehydrogens attachedat C-1 andC-2
could be determined by the magnitude of the coupling constants
and NOESY spectra. The JH/H¼7.8 Hz for 3g and JH/H¼9.1 Hz for 3h
would indicate a dihedral angle of approximately 180ꢀ. Moreover, in
the NOESY spectra no positive NOE was observed between both
hydrogens. Therefore, wehaveassignedthestructureI(1RS,2SR,3SR)
for 3g and 3h.
Nevertheless, the lithium intermediate, resulting from depro-
tonation with LDA of the -phenyl phosphane oxide 1d, in the
presence or absence of electrophiles, was converted in the same
vinylsilane 4b obtained by silyllithiation (Scheme 7).
The diastereoselectivity observed in the reactions of 2a with
electrophiles in the presence of LDA depend on the nature of the
b

A.M. Gonzalez-Nogal et al. / Tetrahedron 66 (2010) 9610e9619
9613
2.2. Reaction of vinylphosphane oxides with stannylcuprates
and stannyllithium reagents
PhS
R
R
1. LiSPh (3 eq.)
2. aq. NH4Cl
PPh2
PPh2
We also looked at the behavior of vinylphosphane oxides toward
O
O
stannylcuprates with the objective of synthesising
phosphane oxides.
b-stannylated
1a; R = Me (Z)
7a (77%)
7b (63%)
7c (75%)
In the same reaction conditions used for the reactions with
silylcuprates, the conjugated addition of the mixed higher-order
lithium butyl(tributylstannyl)cuprate at methyl-, phenyl- or silyl-
phosphane oxides was not possible. The silyl and phenyl substituted
phosphane oxides 1c and 1d were shown to be unreactive toward
the stannyl cuprate and the Z-methyl derivative 1a underwent iso-
merisation giving a mixture of the E isomer 1g and the allylphos-
phane oxide 5 (Scheme 8).
1c; R = SiMe2Ph (E)
1d; R = Ph (E)
Scheme 10.
phosphane oxides 1c and 1d did not add this reagent. Nevertheless,
it is noteworthy that the conjugate addition of the phosphanyl
group on the b-phenyl phosphane oxide 1d was possible by heating
with 2 equiv of diphenylphosphine in toluene at reflux giving 8b
with an acceptable yield (Scheme 11).
1. Bu3Sn(Bu)CNCuLi2
2. aq. NH4Cl
R
+
PPh2
O
O
Ph2P
R
1. LiPPh2 (3.5 eq.)
2. aq. NH4Cl
1c; R = SiMe2Ph
1d; R = Ph
PPh2
R
PPh2
O
O
1a; R = Me (Z)
8a (95%)
Me
1. Bu3Sn(Bu)CNCuLi2
2. aq. NH4Cl
+
PPh2
1c; R = SiMe2Ph (E)
1d; R = Ph (E)
PPh2
Me
PPh2
O
O
O
1a
1e (66%)
O
5 (32%)
Ph2P
Ph
8b (65%)
Ph
Scheme 8.
HPPh2 (2 eq.)
With the aim of achieving the conjugate addition to vinyl-
phosphane oxides of the stannyl group, we tested their reactions
with the more nucleophilic tributylstannyllithium reagent.
The Z-methyl and unsubstituted vinylphosphane oxides 1a and
1e reacted with the tributylstannyllithium affording the corre-
-stannyl compounds 6a and 6b. However, the
-phenyl vinylphosphane oxides 1c and 1d did not experience the
-addition of the stannyl group. Probably, the -silyl or -phenyl
Toluene, reflux
PPh2
PPh2
O
O
1d
Scheme 11.
sponding
b
b
b
b-silyl and
2.4. 1,3-Dipolar cycloadditions of alkenylphosphane oxides
b
b
substituent increases the steric impedance and consequently pre-
The reactivity of these substrates as dipolarophiles is low and
vents the addition in the b-position (Scheme 9).
practically is limited to b-unsubstituted alkenylphosphane oxides.
They have been used in cycloaddition reactions with nitrile oxides
and nitrones to provide phosphanyl isoxazolines and iso-
xazolidines, respectively.
R
Bu3Sn
R
1. Bu3SnLi, –78 ºC 0 ºC
2. aq. NH4Cl
PPh2
PPh2
We have tried to synthesize phosphanylpyrazoles by the 1,3-
dipolar cycloaddition of the vinylphosphane oxides 1a and 1d with
trimethylsilyldiazomethane and N-phenylsydnone. In the reactions
with trimethylsilyldiazomethane the starting products were re-
covered. On the other hand, the cycloaddition reactions with N-
phenylsydnone proceeded with difficulty. High temperature and
long reactions times (150 ꢀC for 70 h) were necessary for the cy-
cloaddition with 1a to take place. In these conditions, we pre-
dominantly obtained13 the 3-methyl-1-phenyl-4-phosphanyl
pyrazole 9 together with the 4-methyl-1-phenyl-3-phosphanyl
O
O
1a; R = Me (Z)
1c; R = SiMe2Ph (E)
6a (68%)
6b (42%)
1d; R = Ph (E)
1e; R = H
Scheme 9.
2.3. Reaction of vinylphosphane oxides with lithium
sulphides and phosphides
pyrazole 10. The E b-phenyl alkenylphosphane oxide 1d was shown
to be unreactive (Scheme 12).
An interesting application of the vinylphosphane oxides is their
use as Michael acceptors toward sulfur and phosphorus nucleo-
philes to synthesise precursors of the useful bidentate 1,2-donor
ligands for transitionemetal catalysed synthesis.
It can be postulated that the formation of phosphanylpyrazoles 9
and 10 arises by way of two possible E and F cycloadducts. The major
product 9 should result from the orientation in which the carbon ter-
minus of N-phenylsydnone is bonded at the a-C of the vinylphosphane
Z or E
b
-Substituted alkenylphosphane oxides 1a, 1c, and 1d
oxide. The pyrazoles 9 and 10 should be formed by spontaneous aro-
matization of the corresponding 2-pyrazolines resulting from loss of
CO2 in the intermediate E and F adducts, respectively (Scheme 13).
These heteroaryldiphenylphosphane oxides, easily converted in
the corresponding phosphanes,14 can be used as building blocks for
reacted with 3 equiv of the lithium phenylsulfide yielding the
-phenylthio phosphane oxides 7aec (Scheme 10).
b
When the lithium diphenylphosphide was used as a nucleophile
the conjugate addition took place exclusively on the
phosphane oxide 1a to give the 1,2-diphosphanyl derivative 8a
with an excellent yield. The more hindered -silyl and -phenyl
b-methyl
the linkage of the desirable features of the organic
p-conjugated
b
b
unit (e.g., semiconductivity, luminescence, flexibility) with some

9614
A.M. Gonzalez-Nogal et al. / Tetrahedron 66 (2010) 9610e9619
electronically interesting functional properties of metal complexes
(e.g., optical, magnetic).15
It could also be proved that the b-hydroxyalkenylphosphane ox-
ides 11b,c are readily converted in versatile allenes16 12a,b by basic
treatment under HornereWittig elimination conditions (Scheme 15).
Although this methodology had been previously used,8 it is
noteworthy that its application to silylated substrates has permit-
ted us the synthesis of the interesting and more versatile silyl
allene17 12a.
R
Me3Si-CH-N=N
+
PPh2
O
1a; R = Me (Z)
1d; R = Ph (E)
HO
R
iPr
PPh2
O
O
R
NaH, DMF
50 ºC
O
R
PPh2
Ph2P
R
iPr
R
O
150 ºC, 70 h
+
+
N
N
N
O
PPh2
N
N
N
O
Ph
Ph
Ph
11b; R = SiMe2Ph
11c; R = Ph
12a (57%)
12b (65%)
9 (42%)
10 (11%)
1a; R = Me (Z)
1d; R = Ph (E)
Scheme 15.
Scheme 12.
3. Conclusions
O
In summary, we have explored the conjugate addition of het-
eroatomic nucleophiles (silyl- and stannyl-lithium and cuprates, or
lithium phenylsulfide and diphenylphosphide) at stereodefined
vinylphosphane oxides previously prepared by regio- and stereo-
specific cleavage of silyloxiranes with lithium diphenylphosphide.
Ph2P
Me
N
N
Ph
9
The most interesting results were obtained by
a-deprotonation of
the -silylated phosphane oxide resulting from silylcupration and
subsequent reaction with electrophiles. The reaction, which oc-
curred with total or partial diastereoselectivity has turned out to be
b
O
Ph
N
Ph2P
Me
Me
-CO2
N
O
a useful stereoselective route to synthesise
a-functionalized b-
N
N
Ph
H
PPh2
O
N
N
silylated phosphane oxides containing two or three chiral carbons.
On the other hand, the Michael addition of sulfur or phosphorus
nucleophiles afforded precursors of bidentate 1,2-donord ligands
used in homogeneous catalysis. Moreover, the formation of
a sulfureC bond constitutes a key reaction in biosynthesis as well as
in the chemical synthesis of biologically potent compounds18 and
the introduction of a second phosphane group gives rise to P,P-
chelate metal complexes, in which their electronic properties could
be improved. Likewise, the heteroarylphosphanes due to the ability
of P-centers to coordinate to transition metals offer manifold op-
O
Ph
O
O
150 ºC
E
+
O
Ph
O
O
Me
PPh2
N
N
Me
PPh2
-CO2
PPh2
O
N
H
Me
N
O
Ph
F
O
portunities to build supramolecular architectures in which the
p-
Me
PPh2
systems can be organized in a well-defined manner. Finally, the
availability of cumulative double bonds in silylallenes makes these
compounds valuable precursors of versatile allyl- or vinyl-silanes.
N
N
10
Ph
4. Experimental
4.1. General
Scheme 13.
2.5. Reactions of vinylphosphane oxides with aldehydes in
the presence of LDA. Synthesis of allenes
THF was distilled from sodium benzophenone ketyl in a recy-
cling still. All chromatographic and work-up solvents were distilled
prior to use. Copper(I)cyanide was dried in vacuo over P2O5. The
mixed butyl(dimethylphenylsilyl)- and butyl(tert-butyldiphe-
nylsilyl)-cuprate reagents were prepared mixing 1 equiv of the
corresponding silyllithium, 1 equiv of butyllithium and 1 equiv of
copper(I) cyanide.19 The mixed butyl(tributylstannyl)cuprate was
prepared in the same way.20 The trimethylsilyldiazomethane is
commercial (Aldrich) and the N-phenylsydnone was synthesised
starting from N-phenylglicine.21 All reactions involving organo-
metallic reagents were carried out under nitrogen atmosphere. 1H,
13C, and 31P NMR spectra were recorded at 300, 75 and 121 MHz,
respectively, in CDCl3 as an internal standard. Carbon multiplicities
were assigned by DEPT experiments. Reactions were monitored by
TLC on a pre-coated plate of silica gel 60 (nano-SIL-20, Macher-
eyeNagel). Flash chromatography was performed on silica gel 60
(230e400 mesh, M-N). The starting alkenylphosphane oxides were
The alkenylphosphane oxides 1a, 1c, and 1d reacted with iso-
butyraldehyde and lithium diisopropylamide by a BayliseHillman
type reaction8 leading to the (E)-
11aec (Scheme 14).
b-hydroxyphosphane oxides
HO
R1
R1
iPr
LDA (1.1 eq.)
iPrCHO (1.1 eq.)
THF, –78 ºC
PPh2
PPh2
O
O
1a; R1 = Me (Z)
11a (47%)
11b (58%)
1c; R1 = SiMe2Ph (E)
1d; R1 = Ph (E)
11c (64%)
Scheme 14.

A.M. Gonzalez-Nogal et al. / Tetrahedron 66 (2010) 9610e9619
9615
previously prepared by us5 from epoxysilanes by regio- and stereo-
specific cleavage with lithium diphenylphosphide.
(300 MHz, CDCl3)
d
0.22 (s, 3H), 0.27 (s, 3H), 2.65 (ddd, J¼2.3, 15.9,
28.5 Hz, 1H), 2.72 (dt, J¼7.2, 15.9 Hz, 1H), 2.88 (ddd, J¼2.3, 10.9,
15.9 Hz, 1H), 6.73e7.60 (m, 20H); 13C NMR (75 MHz, CDCl3)
d
ꢁ5.5,
4.2. Silylcupration of alkenylphosphane oxides and trapping
with electrophiles. General procedure
ꢁ4.1, 28.6 (d, J¼5.8 Hz), 30.1 (d, J¼67.3 Hz), 124.7, 127.7, 127.9, 128.0,
128.4 (d, J¼11.3 Hz), 129.3, 130.6 (d, J¼8.9 Hz), 130.8 (d, J¼9.3 Hz),
131.4, 1325 (d, J¼103.6 Hz), 133.9 (d, J¼96.6 Hz), 134.3, 136.3, 140.9;
ATHF solution of the lithium butyl(dimethylphenylsilyl)cuprate or
butyl(tert-butyldiphenylsilyl)cuprate (2 mmol) was added at ꢁ78 ꢀC
under N2 to a stirred solution of the alkenylphosphane oxides 1aed
(1 mmol) in THF (5 mL). The mixture was stirred for 1 h and then the
electrophile (3 mmol) was added at ꢁ78 ꢀC. The mixture was slowly
allowed to warm to 0 ꢀC and stirred at this temperature until TLC
indicatedcompletereaction. Thereactionmixturewasthenquenched
at 0 ꢀC with aqueous ammonium chloride, extracted with ether and
the organic layer dried (MgSO4). The ethereal solvents were evapo-
rated and the residue chromatographed to give the following
compounds.
31P NMR (121 MHz, CDCl3)
d 32.28; [found: C, 76.57; H, 6. 46.
C28H29OPSi (440.17) requires C, 76.33; H, 6.63%].
4.2.6. [2-(tert-Butydiphenylsilyl)-2-phenylethyl]diphenylphosphane
oxide (2f). Yield: 234 mg (43%); Rf (AcOEt) 0.36; IR (CHCl3) 1190,
1118 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
0.79 (s, 9H), 2.49 (ddd, J¼4.7,
12.1,15.1 Hz,1H), 2.82 (t, J¼15.1 Hz,1H), 3.81 (dd, J¼12.1,16.0 Hz,1H),
6.72e7.74 (m, 25H); 13C NMR (75 MHz, CDCl3)
19.1, 23.0, 27.8, 33.0
d
(d, J¼66.8 Hz), 125.3, 127.4, 127.5, 127.6, 127.8, 128.4 (d, J¼11.2 Hz),
129.3, 129.5, 130.3 (d, J¼9.5 Hz), 130.5 (d, J¼2.3 Hz), 130.8 (d,
J¼9.7 Hz), 131.3 (d, J¼2.2 Hz), 132.0 (d, J¼96.4 Hz), 133.4, 133.7, 134.9
(d, J¼95.0 Hz),137.1,141.2; 31P NMR (121 MHz, CDCl3)
d 31.42; [found:
4.2.1. [2-(Dimethylphenylsilyl)propyl]diphenylphosphane oxide (2a).
Yield: 279 mg (74%); Rf (AcOEt) 0.40; mp 95e98 ꢀC (from Et2O/
C, 79. 61; H, 6.62. C36H37OPSi (544.24) requires C, 79.37; H, 6.85%].
hexane); IR (CHCl3) 1258, 1183, 1117 cmꢁ1
;
1H NMR (300 MHz,
4.2.7. Ethyl
silyl)butanoate (syn-3a). Yield: 49 mg (11%); Rf (AcOEt/CH2Cl2 9:1)
0.73; IR (CHCl3) 1725, 1258, 1183, 1117 cmꢁ1 1H NMR (300 MHz,
CDCl3)
0.25 (s, 3H), 0.28 (s, 3H), 0.89 (t, J¼7.1 Hz, 3H), 1. 36 (d,
(2RS,3SR)-2-(diphenylphosphany)l-3-(dimethylphenyl
CDCl3)
2.00 (dt, J¼15.2, 11.8 Hz, 1H), 2.29 (ddd, J¼1.2, 8.3, 15.2 Hz, 1H),
7.33e7.77 (m, 15H); 13C NMR (75 MHz, CDCl3)
d
0.26 (s, 3H), 0.28 (s, 3H), 1.13 (d, J¼7.3 Hz, 3H), 1.40 (m, 1H),
;
d
ꢁ6.3, ꢁ5.0, 13.3 (d,
d
J¼6.6 Hz), 15.3, 30.7 (d, J¼67.8 Hz), 127.8, 128.4 (d, J¼11.2 Hz), 129.1,
130.3 (d, J¼9.1 Hz), 130.8 (d, J¼8.8 Hz), 131.3, 132.6 (d, J¼96.6 Hz),
133.9, 134.6 (d, J¼95.1 Hz), 136.9; 31P NMR (121 MHz, CDCl3)
J¼7.5 Hz, 3H), 1.58 (m, 1H), 3.50 (dd, J¼1.7, 9.2 Hz, 1H), 3.84 (q,
J¼7.1 Hz, 2H), 7.19e8.06 (m, 15H); 13C NMR (75 MHz, CDCl3)
ꢁ5.5,
d
ꢁ4.5, 11.5, 13.5, 18.4, 46.6 (d, J¼61.0 Hz), 60.8, 127.5, 128.4 (d,
J¼11.2 Hz), 129.1, 130.3 (d, J¼9.1 Hz), 130.8 (d, J¼8.8 Hz), 131.3, 132.6
(d, J¼96.6 Hz), 133.9, 134.6 (d, J¼95.1 Hz), 136.8, 168.9; 31P NMR
d
33.96; [found: C, 73.36; H, 6. 98. C23H27OPSi (378.16) requires C,
72.98; H, 7.19%].
(121 MHz, CDCl3)
d 29.83; [found: C, 69.63; H, 7.25. C26H31O3PSi
4.2.2. [2-(tert-Butyldiphenylsilyl)propyl]diphenylphosphane oxide (2b).
Yield: 337 mg (70%); Rf (AcOEt) 0.38; IR (CHCl3) 1180, 1120 cmꢁ1; 1H
(450.18) requires C, 69.31; H, 6.93%].
NMR (300 MHz, CDCl3)
d
1.08 (s, 9H), 1.40 (d, J¼6.7 Hz, 3H), 2.12 (m,
4.2.8. Ethyl
(2RS,3RS)-2-(diphenylphosphanyl)-3-(dimethylphenyl
2H), 2.53 (dd, J¼9.2, 13.4 Hz, 1H), 7.27e7.78 (m, 20H); 13C NMR
silyl)butanoate (anti-3a). Yield: 162 mg (36%); Rf (AcOEt/CH2Cl2 9:1)
(75 MHz, CDCl3)
d
11.2 (d, J¼6.4 Hz), 17.0, 18.9, 29,1, 32.0 (d, J¼67.0 Hz),
0.71; mp 120e122 ꢀC (from Et2O/hexane); IR (CHCl3) 1725,1258,1183,
127.3, 127.7, 128.5 (d, J¼12.7 Hz), 128.6 (d, J¼10.2 Hz), 129.2, 129.3,
130.5 (d, J¼8.7 Hz), 130.8 (d, J¼8.9 Hz), 131.4 (d, J¼2.2 Hz), 133.0 (d,
J¼96.5 Hz), 133.3, 134.1, 134.5 (d, J¼94.2 Hz), 136.4; 31P NMR
1117 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d 0.26 (s, 3H), 0.29 (s, 3H), 0.69
(t, J¼7.3 Hz, 3H), 0.99 (d, J¼7.5 Hz, 3H), 2.04 (m,1H), 3.03 (m,1H), 3.34
(m, 1H), 3.44 (dd, J¼12.3, 13.0 Hz, 1H), 7.26e8.16 (m, 15H); 13C NMR
(121 MHz, CDCl3)
d
33.44; [found: C, 76.89; H, 7.60. C31H35OPSi
(75 MHz, CDCl3)
d
ꢁ4.6, ꢁ4.2,13.1,14.2 (d, J¼5.7 Hz),19.2 (d, J¼4.9 Hz),
(482.22) requires C, 77.14; H, 7.31%].
52.5 (d, J¼54.8 Hz), 60.8, 127.5, 128.4 (d, J¼11.2 Hz), 129.1, 130.3 (d,
J¼9.1Hz),130.8(d,J¼8.8Hz),131.3,132.6(d, J¼96.6 Hz),133.9,134.6 (d,
4.2.3. [2-(Dimethylphenylsilyl)hexyl]diphenylphosphane oxide (2c).
Yield: 281 mg (67%); Rf (AcOEt) 0.41; IR (CHCl3) 1255, 1180,
J¼95.1 Hz),136.8,170.3; 31P NMR (121 MHz, CDCl3)
d 28.98; [found: C,
69.11; H, 6. 75. C26H31O3PSi (450.18) requires C, 69.31; H, 6.93%].
1110 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d 0.29 (s, 3H), 0.31 (s, 3H), 0.72
(t, J¼7.1 Hz, 3H), 1.08 (m, 4H), 1.37 (m, 1H), 1.55 (m, 2H), 2.14 (dt,
4.2.9. (2RS,3SR)-[2-(Dimethylphenylsilyl)hex-5-en-3-yl]diphenyl
J¼15.3, 11.0 Hz, 1H), 2.27 (ddd, J¼2.7, 9.9, 15.3 Hz, 1H), 7.32e7.69 (m,
phosphane oxide (syn-3b). Yield: 50 mg (12%); Rf (AcOEt) 0.75; IR
15H); 13C NMR (75 MHz, CDCl3)
d
ꢁ4.7, ꢁ3.6, 13.8, 18,8 (d, J¼6.0 Hz),
(CHCl3) 1638, 1258, 1182, 1120 cmꢁ1 1H NMR (300 MHz, CDCl3)
;
22.8, 29.3 (d, J¼67.9 Hz), 30.3, 30.9, 127.8,128.4 (d, J¼11.4 Hz),129.0,
130.5 (d, J¼8.9 Hz), 130.8 (d, J¼8.9 Hz), 131.3, 133.1 (d, J¼96.7 Hz),
d
0.35 (s, 3H), 0.36 (s, 3H), 1.01 (d, J¼7.7 Hz, 3H), 1.57 (m, 1H), 2.24
(m, 1H), 2.44 (m, 1H), 2.60 (m, 1H), 4.79 (dd, J¼1.6, 17.0 Hz, 1H), 4.89
(dd, J¼1.6, 10.0 Hz,1H), 5.55 (ddt, J¼10.0,17.0, 6.9 Hz,1H), 7.29e7.80
133.9,134.5 (d, J¼97.5 Hz),137.9; 31P NMR (121 MHz, CDCl3)
d 32.97;
[found: C, 73.96; H, 6. 77. C26H33OPSi (420.20) requires C, 74.25; H,
7.91%].
(m, 15H); 13C NMR (75 MHz, CDCl3)
d
ꢁ3.1, ꢁ3.0, 14.0 (d, J¼8.5 Hz),
20.0, 33.5, 40.8 (d, J¼69.5 Hz),116.8,127.6,128.3 (d, J¼11.1 Hz),128.5
(d, J¼11.2 Hz), 128.7, 130.7 (d, J¼8.6 Hz), 130.8, 131.3 (d, J¼10.1 Hz),
131.5, 133.5 (d, J¼94.7 Hz), 134.0, 134.3 (d, J¼93.7 Hz), 136.4 (d,
4.2.4. [2,2-Bis(dimethylphenylsilyl)ethyl]diphenylphosphane oxide
(2d). Yield: 293 mg (59%); Rf (AcOEt) 0.46; IR (CHCl3) 1266, 1187,
J¼10.9 Hz), 139.2; 31P NMR (121 MHz, CDCl3)
d 35.12; [found: C,
1112 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
0.19 (s, 6H), 0.26 (s, 6H),
0.83 (dt, J¼21., 5.8 Hz, 1H), 2.40 (dd J¼5..8, 12.5 Hz, 2H), 7.15e7.57
(m, 20H); 13C NMR (75 MHz, CDCl3)
74.43; H, 7. 22. C26H31OPSi (418.19) requires C, 74.60; H, 7.46%].
d
ꢁ1.8, ꢁ1.5, 4.4 (d, J¼6.6 Hz),
4.2.10. (2RS,3RS)-[2-(Dimethylphenylsilyl)hex-5-en-3-yl]diphenyl
26.3 (d, J¼66.9 Hz), 127.6, 128.4 (d, J¼11.0 Hz), 128.8, 130.8 (d,
phosphane oxide (anti-3b). Yield: 163 mg (39%); Rf (AcOEt) 0.81; IR
J¼8.8 Hz), 131.2, 133.5 (d, J¼94.9 Hz), 134.2, 139.3; 31P NMR
(CHCl3) 1638, 1250, 1183, 1122 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d 0.26
(121 MHz, CDCl3)
d
31.85; [found: C, 72.52; H, 6. 81. C30H35OPSi2
(s, 3H), 0.34 (s, 3H),1.22 (d, J¼7.7 Hz, 3H),1.41 (m,1H), 2.35 (m, 2H), 2.63
(m, 1H), 4.60 (dd, J¼1.4, 10.0 Hz, 1H), 4.72 (dd, J¼1.4, 17.0 Hz, 1H), 5.26
(ddt, J¼10.0, 17.0, 7.0 Hz, 1H), 7.32e7.67 (m, 15H); 13C NMR (75 MHz,
(498.20) requires C, 72.25; H, 7.07%].
4.2.5. [2-(Dimethylphenylsilyl)-2-phenylethyl]diphenylphosphane
CDCl3)
d
ꢁ4.2, ꢁ3.9, 10.3, 19.7, 29.1, 37.0 (d, J¼66.4 Hz), 115.8, 127.8,
oxide (2e). Yield: 228 mg (52%); Rf (AcOEt) 0.45; mp 189e191 ꢀC
128.2 (d, J¼10.9 Hz),128.5 (d, J¼11.1 Hz),129.3,130.8 (d, J¼8.3 Hz),131.1,
132.9 (d, J¼94.4 Hz), 133.6, 134.1 (d, J¼89.2 Hz), 136.9 (d, J¼93.7 Hz),
(from Et2O/hexane); IR (CHCl3) 1262, 1180, 1118 cmꢁ1 1H NMR
;

9616
A.M. Gonzalez-Nogal et al. / Tetrahedron 66 (2010) 9610e9619
136.4 (d, J¼5.4 Hz),137.6; 31P NMR (121 MHz, CDCl3)
d
37.57; [found: C,
hexane); IR (CHCl3) 1258, 1184, 1120 cmꢁ1
CDCl3)
0.27 (s, 6H), 0.98 (dd, J¼7.1, 17.7 Hz, 2H), 2.13 (dt, J¼7.1,
9.7 Hz, 2H), 7.28e7.81 (m, 15H); 13C NMR (75 MHz, CDCl3)
;
1H NMR (300 MHz,
74.86; H, 7. 63. C26H31OPSi (418.19) requires C, 74.60; H, 7.46%].
d
d
ꢁ3.5,
4.2.11. [1,1-Bis(dimethylphenylsilyl)pent-4-en-2-yl]diphenylphos-
6.0 (d, J¼7.1 Hz), 23.5 (d, J¼69.6 Hz), 127.9, 128.4 (d, J¼11.2 Hz),
129.1, 130.3 (d, J¼9.1 Hz), 130.8 (d, J¼8.8 Hz), 131.3, 132.6 (d,
J¼96.6 Hz), 133.9, 134.3 (d, J¼95.1 Hz), 137.5; 31P NMR (121 MHz,
phane oxide (3c). Yield: 269 mg (50%); Rf (AcOEt) 0.75; IR (CHCl3)
1640, 1255, 1187, 1123 cmꢁ1 1H NMR (300 MHz, CDCl3)
; d 0.36 (s,
3H), 0.38 (s, 3H), 0.55 (s, 3H), 0.57 (s, 3H), 1.45 (m, 1H), 2.54 (m, 2H),
2.84 (m, 1H), 4.63 (dd, J¼1.6, 9.9 Hz, 1H), 4. 95 (dd, J¼1.6, 17.0 Hz,
1H), 5.35 (ddt, J¼9.9, 17.0, 7.1 Hz, 1H), 7.19e7.70 (m, 20H); 31P NMR
CDCl3)
d 35.72; [found: C, 72.23; H, 7 18. C22H25OPSi (364.14) re-
quires C, 72.49; H, 6.91%].
(121 MHz, CDCl3)
d 34.68; [found: C, 73.81; H, 7.52. C33H39OPSi2
4.3.5. [2-(Dimethylphenylsilyl)-2-(trimethylsilyl)ethyl]diphenyl
(538.23) requires C, 73.56; H, 7.30%].
phosphane oxide (2h). Yield: 196 mg (45%); Rf (AcOEt) 0.45; IR
(CHCl3) 1251, 1190, 1112 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
ꢁ0.06 (s,
4.2.12. (1RS,2SR)-[1-(Dimethylphenylsilyl)-1-phenylpent-4-en-2-yl]
9H), 0.28 (s, 6H), 0.31 (s, 6H), 0.60 (ddd, J¼4.4, 7.2, 22.3 Hz, 1H), 2.30
(ddd, J¼7.2, 12.7, 15.4 Hz, 1H), 2.43 (ddd, J¼4.4, 10.8, 15.4 Hz, 1H),
diphenylphosphane oxide (syn-3d). Yield: 48 mg (10%); Rf (AcOEt/
CH2Cl2 9:1) 0.64; IR (CHCl3) 1634, 1250, 1185, 1120 cmꢁ1 1H NMR
;
7.33e7.53 (m,15H); 13C NMR (75 MHz, CDCl3)
d
ꢁ2.2, ꢁ1.5, 0.2, 4.1 (d,
(300 MHz, CDCl3):
d
¼0.15 (s, 3H), 0.45 (s, 3H), 2.52 (m, 1H), 2.61 (m,
J¼6.3 Hz), 26.1 (d, J¼67.0 Hz), 128.1, 128.4 (d, J¼11.8 Hz), 128.9, 130.8
2H), 3.07 (m, 1H), 4.64 (dd, J¼1.6, 10.3 Hz, 1H), 4. 77 (dd, J¼1.6,
(d, J¼9.6 Hz), 131.0 (d, J¼10.3 Hz), 131.5, 133.2 (d, J¼97.1 Hz), 134.0,
17.0 Hz, 1H), 5.32 (m, 1H), 7.08e7.74 (m, 20H); 13C NMR (75 MHz,
134.1(d, J¼95.9 Hz),139.4; 31P NMR (121 MHz, CDCl3)
d 31.61; [found:
CDCl3)
d
ꢁ4.8, ꢁ3.8, 31.9, 35.6, 39.8 (d, J¼68.3 Hz), 116.2, 124.3,
C, 69.01; H, 7. 80. C25H33OPSi2 (436.18) requires C, 68.76; H, 7.62%].
127.5, 127.9, 128.0, 128.4 (d, J¼11.3 Hz), 129.6, 130.9 (d, J¼8.9 Hz),
131.8 (d, J¼9.3 Hz), 132.4, 132.7 (d, J¼93.6 Hz), 134.8 (d, J¼92.6 Hz),
4.3.6. E-1-(tert-Butyldiphenylsilyl)-2-(dimethylphenylsilyl)ethene
(4a). Yield: 236 mg (59%).
134.3, 136.3, 142.4; 31P NMR (121 MHz, CDCl3)
d 35.93; [found: C,
77.71; H, 7.15. C31H33OPSi (480.20) requires C, 77.46; H, 6.92%].
4.3.7. E-1-(Dimethylphenylsilyl)-2-phenylethene (4b). Yield: 183 mg
(77%)22
4.2.13. (1RS,2RS)-[1-(Dimethylphenylsilyl)-1-phenylpent-4-en-2-yl]
diphenylphosphane oxide (anti-3d). Yield: 168 mg (35%); Rf (AcOEt/
CH2Cl2 9:1) 0.62; IR (CHCl3) 1636, 1250, 1180, 1120 cmꢁ1 1H NMR
;
4.3.8. E-1-(tert-Butyldiphenylsilyl)-2-phenylethene(4c). Yield: 232 mg
(68%)23
(300 MHz, CDCl3)
d
0.42 (s, 6H), 1.09 (s, 9H), 6.77 (d, J¼22.6 Hz, 1H),
7.08 (m, 2H), 3.15 (m,1H), 4.57 (dd, J¼1.6,17.0 Hz,1H), 4. 68 (dd, J¼1.6,
10.4 Hz, 1H), 5.46 (m, 1H), 7.10e7.61 (m, 20H); 13C NMR (75 MHz,
4.4.
a-Deprotonation of the b-silylated phosphane oxides and
CDCl3)
d
ꢁ2.5, ꢁ1.8, 33.3, 36.4, 46.7 (d, J¼66.9 Hz),116.3,124.9,127.8,
capture with electrophiles. General procedure
127.9, 128.1, 128.4 (d, J¼11.3 Hz), 129.6, 130.9 (d, J¼8.9 Hz), 131.8 (d,
J¼9.3 Hz), 132.4, 132.7 (d, J¼85.3 Hz), 134.2 (d, J¼96.8 Hz), 133.7,
A solution of the b-silyl phosphane oxides 2a or 2d (1 mmol) in
135.8, 143.6; 31P NMR (121 MHz, CDCl3)
d 35.35; [found: C, 77.23; H,
dry THF (3 mL) was added to a stirred THF solution of lithium dii-
sopropylamide (2 mmol) [prepared from diisopropylamine
(0.28 mL, 2 mmol) and BuLi (1.25 mL, 1.6 M solution in hexane,
2 mmol) in dry THF (3 mL) at ꢁ20 ꢀC under N2 for 15 min]. The
mixture was stirred at 0 ꢀC for 30 min and then was added the
electrophile (3 mmol) and the system was stirred at this temper-
ature and then warmed to room temperature until TLC indicated
complete reaction (reaction time¼1e10 h). The mixture was
hydrolysed with a saturated aqueous NH4Cl solution and extracted
with diethyl ether, and the organic layer was dried (MgSO4). The
residue obtained after evaporation of ether was purified by flash
chromatography on silica gel using AcOEt/CH2Cl2 or hexane as el-
uents to give the compounds characterized below.
6. 77. C31H33OPSi (480,20) requires C, 77.46; H, 6.92%].
4.2.14. E-1-(tert-Butyldiphenylsilyl)-2-(dimethylphenylsilyl)ethene
(4a). Yield: 248 mg (62%); Rf (hexane) 0.36; IR (CHCl3) 1590, 1250,
1112, 1010 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
d
0.42 (s, 6H), 1.09 (s,
9H), 6.77 (d, J¼22.5 Hz, 1H), 7.08 (d, J¼22.5 Hz, 1H), 7.20e7.41 (m,
9H), 7.53e7.60 (m, 6H); 13C NMR (75 MHz, CDCl3)
d
ꢁ2.6, 18.3, 27.9,
127.6,129.0,134.1,135.8,138.7,152.2,157.5; [found: C, 77.68; H, 7.86.
C26H32Si2 (400,20) requires C, 77.93; H, 8.05%].
4.3. Silyllithiation of alkenylphosphane oxides. Typical
procedure
Dimethylphenyl- or tert-butyldiphenylsilyllithium (2 mmol)
was added at 0 ꢀC under N2 to a stirred solution of the vinyl-
phosphane oxides 1a, 1c, 1e or 1f (1 mmol) in dry THF (3 mL). The
mixture was stirred at 0 ꢀC until TLC indicated complete reaction.
Quenching at that temperature with aqueous ammonium chloride,
aqueous work-up with diethyl ether, drying (MgSO4), and chro-
matography gave the following products.
4.4.1. (2RS,3SR)-[2-(Dimethylphenylsilyl)hex-5-en-3-yl]diphenyl
phosphane oxide (syn-3b). Yield: 83 mg (20%).
4.4.2. (2RS,3RS)-[2-(Dimethylphenylsilyl)hex-5-en-3-yl]diphenyl
phosphane oxide (anti-3b). Yield: 158 mg (38%).
4.4.3. (1RS,2SR)-1-Benzoyl-[2-(dimethylphenylsilyl)propyl]diphenyl
phosphane oxide (syn-3e). Yield: 72 mg (15%); Rf (AcOEt/CH2Cl2
4.3.1. [2-(Dimethylphenylsilyl)propyl]diphenylphosphane oxide (2a).
1:1) 0.39; IR (CHCl3) 1682, 1258, 1182, 1120 cmꢁ1 1H NMR
;
Yield: 185 mg (49%).
(300 MHz, CDCl3)
d
0.05 (s, 3H), 0.15 (s, 3H), 1.38 (d, J¼7.5 Hz, 3H),
2.05 (m, 1H), 4.59 (dd, J¼2.5, 13.3 Hz, 1H), 7.09e8.25 (m, 20H); 13C
4.3.2. [2-(tert-Butyldiphenylsilyl)propyl]diphenylphosphane oxide
(2b). Yield: 303 mg (63%).
NMR (75 MHz, CDCl3)
d
ꢁ5.3, ꢁ3.3, 12.0, 21.0, 49.0 (d, J¼57.0 Hz),
125.5, 127.6, 128.7(d, J¼11.9 Hz), 129.3, 130.7 (d, J¼9.6 Hz), 131.5,
131.8, 132.3 (d, J¼99.5 Hz), 136.5, 136.8 138.7, 197.7; 31P NMR
4.3.3. [2,2-Bis(dimethylphenylsilyl)ethyl]diphenylphosphane oxide
(121 MHz, CDCl3) d 31.02; [found: C, 74.82; H, 6.28. C30H31O2PSi
(2d). Yield: 283 mg (57%).
(482.18) requires C, 74.66; H, 6.47%].
4.3.4. [2-(Dimethylphenylsilyl)ethyl]diphenylphosphane oxide (2g).
Yield: 236 mg (65%); Rf (AcOEt) 0.35; mp 142e144 ꢀC (from Et2O/
4.4.4. (1RS,2RS)-1-Benzoyl-[2-(dimethylphenylsilyl)propyl]diphenyl
phosphane oxide (anti-3e). Yield: 197 mg (41%); Rf (AcOEt/CH2Cl2

A.M. Gonzalez-Nogal et al. / Tetrahedron 66 (2010) 9610e9619
9617
1:1) 0.37; IR (CHCl3) 1680, 1252, 1180, 1118 cmꢁ1
;
1H NMR
7.40e7.56 (m, 6H), 7.69e7.78 (m, 4H); 13C NMR (75 MHz, CDCl3)
(300 MHz, CDCl3)
d
0.14 (s, 3H), 0.20 (s, 3H), 1.18 (d, J¼7.5 Hz, 3H),
d
36.0 (d, J¼68.7 Hz), 121.0 (d, J¼11.8 Hz), 128.5 (d, J¼9.3 Hz), 129.1
2.30 (m, 1H), 4.79 (dd, J¼11.7, 18.5 Hz, 1H), 7.09e8.25 (m, 20H); 13C
(d, J¼11.7 Hz), 131.0 (d, J¼9.1 Hz), 131.8, 133.2 (d, J¼99.1 Hz); 31P
NMR (75 MHz, CDCl3)
d
ꢁ3.9, ꢁ2.7, 14.2, 20.7, 54.1 (d, J¼49.4 Hz),
NMR (121 MHz, CDCl3) d 30.70; [found: C, 74.10; H, 6.42. C15H15OP
(242.09) requires C, 74.37; H, 6.24%].
124.7, 127.3, 128.1(d, J¼13.1Hz), 129.1, 130.5 (d, J¼9.7 Hz), 131.5,
132.1, 133.3 (d, J¼101.5 Hz), 135.2, 137.0, 138.3, 198.4; 31P NMR
(121 MHz, CDCl3)
d
30.23; [found: C, 74.42; H, 6. 61. C30H31O2PSi
4.6. Stannyllithiation of alkenylphosphane oxides. General
procedure
(482.18) requires C, 74.66; H, 6.47%].
4.4.5. (1RS,2RS)-1-Iodo-[2-(dimethylphenylsilyl)propyl]diphenyl
phosphane oxide (anti-3f). Yield: 226 mg (45%); Rf (AcOEt) 0.63; IR
Tributylstannyllithium (2 mmol) was added at ꢁ78 ꢀC under N2
to a stirred solution of the vinylphosphane oxides 1a, 1c, 1d or 1e
(1 mmol) in dry THF (3 mL). The mixture was stirred at this tem-
perature for 2 h and then was allowed to warm to 0 ꢀC and stirred
until TLC indicated complete reaction. Quenching at that temper-
ature with aqueous ammonium chloride, aqueous work-up with
diethyl ether, drying (MgSO4), and chromatography gave the fol-
lowing products.
(CHCl3) 1250, 1180, 1118 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
0.25 (s,
3H), 0.46 (s, 3H), 1.14 (q, J¼6.7 Hz, 1H), 1.29 (d, J¼6.7 Hz, 3H), 4.42 (s,
1H), 7.28e7.68 (m, 15H); 13C NMR (75 MHz, CDCl3)
d
ꢁ5.1, ꢁ4.1, 14.7,
21.8, 29.3 (d, J¼63.2 Hz), 128.0, 128.7 (d, J¼11.6 Hz), 129.6, 130.9 (d,
J¼8.4 Hz), 131.7, 132.9 (d, J¼94.1 Hz), 133.9, 136.7; 31P NMR
(121 MHz, CDCl3)
d 32.21; [found: C, 54.55; H, 5.43. C23H26IOPSi
(504.05) requires C, 54.77; H, 5.20%].
4.6.1. Diphenyl-[2-(tributylstannyl)propyl]phosphane oxide (6a).
4.4.6. (1RS,2SR,3SR)-3-(Dimethylphenylsilyl)-1-phenyl-2-(diphenyl
phosphanyl)butan-1-ol (3g). Yield 212 mg (44%); Rf (AcOEt/CH2Cl2
1:1) 0.51; mp 158e160 ꢀC (from Et2O/hexane); IR (CHCl3) 3200,
Yield 363 mg (68%); Rf (AcOEt/CH2Cl2 3:1) 0.34; 1H NMR (300 MHz,
CDCl3)
1.66 (m, 1H), 2.47 (m, 2H), 7.42e7.53 (m, 6H), 7.70e7.79 (m, 4H); 13C
NMR (75 MHz, CDCl3)
d
0.92 (m, 15H), 1.25 (d, J¼7.3 Hz, 3H), 1.20e150 (m, 12H),
1252, 1185, 1110 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
0.04 (s, 3H), 0.19
d
8.4, 11.2, 13.7, 20.1 (d, JC,P¼5.4 Hz), 27.5 (d,
(s, 3H), 1.35 (m, 1H), 1.38 (s, 3H), 2.90 (t, J¼7.8 Hz, 1H), 3.15 (br, s,
JC,Sn¼53.4 Hz), 29.2 (d, JC,Sn¼19.3 Hz), 35.3 (d, JC,P¼64.8 Hz), 128.5
(d, JC,P¼11.3 Hz), 130.5 (d, JC,P¼9.0 Hz), 131.4, 133.6 (d, JC,P¼95.4 Hz);
1H), 5.27 (dd, J¼6.3, 7.8 Hz, 1H), 6.94e7.87 (m, 20H); 13C NMR
(75 MHz, CDCl3)
d
ꢁ3.9, ꢁ3.8, 13.6, 18.9, 44.8 (d, J¼65.7 Hz), 71.5,
31P NMR (121 MHz, CDCl3)
d
32.73 (JP,Sn¼177.0 Hz); [found: C,
126.4, 127.2, 128.5 (d, J¼11.8 Hz), 129.6, 131.3 (d, J¼8.8 Hz), 131.7,
61.01; H, 7.98. C27H43OPSn (534.21) requires C, 60.81; H, 8.13%].
132.9 (d, J¼94.1 Hz), 134.2, 139.4, 142.4; 31P NMR (121 MHz, CDCl3)
d
38.68; [found: C, 74.59; H, 6.63. C30H33O2PSi (484.20) requires C,
4.6.2. Diphenyl-[2-(tributylstannyl)ethyl]phosphane oxide (6b).
Yield 218 mg (42%); Rf (AcOEt/CH2Cl2 3:1) 0.32; 1H NMR (300 MHz,
74.35; H, 6.86%].
CDCl3)
2H), 7.44e7.55 (m, 6H), 7.70e7.80 (m, 4H); 13C NMR (75 MHz,
CDCl3)
8.8, 13.7, 17.6, 27.3 (d, JC,Sn¼52.8 Hz), 27.6 (d, JC,P¼74.6 Hz),
d 0.90 (m, 15H), 1.20e150 (m, 12H), 1.74 (m, 2H), 2.34 (m,
4.4.7. (3RS,4SR,5SR)-2-Methyl-5-(dimethylphenylsilyl)-4-(diphenyl
phosphanyl)hexan-3-ol (3h). Yield 238 mg (53%); Rf (AcOEt/CH2Cl2
1:1) 0.38; mp 141e143 ꢀC (from Et2O/hexane); IR (CHCl3) 3300,
d
29.0 (d, JC,Sn¼19.8 Hz), 128.5 (d, JC,P¼11.2 Hz), 130.9 (d, JC,P¼8.8 Hz),
1250,1185,1110 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
0.23 (s, 3H), 0.38
131.5, 132.8 (d, JC,P¼95.5 Hz); 31P NMR (121 MHz, CDCl3)
d 34.90
(s, 3H), 0.44 (d, J¼6.5 Hz, 3H), 0.84 (d, J¼6.5 Hz, 3H), 1.33 (s, 3H),
1.35 (m, 2H), 2.75 (d, J¼9.0 Hz,1H), 3.52 (dt, J¼25.8, 9.0 Hz,1H), 5.26
(d, J¼9.0 Hz, 1H), 7.30e7.72 (m, 15H); 13C NMR (75 MHz, CDCl3)
(JP,Sn¼198.0 Hz); [found: C, 59.72; H, 8.28. C26H41OPSn (520.19)
requires C, 60.14; H, 7.96%].
d
ꢁ4.5, ꢁ3.3, 11.8, 19.7, 19.9, 21.9, 34.0, 37.9 (d, J¼61.9 Hz), 80.2 (d,
4.7. Reactions of the alkenylphosphane oxides with lithium
sulphides and phosphides. General procedure
J¼4.1 Hz),127.9,128.4 (d, J¼11.2 Hz),129.4,130.3 (d, J¼8.5 Hz),131.5,
132.7 (d, J¼96.2 Hz), 134.0, 135.0 (d, J¼89.4 Hz), 137.7; 31P NMR
(121 MHz, CDCl3)
d
43.12; [found: C, 71.72; H, 7.98. C27H35O2PSi
A solution of a vinylphosphane oxide 1a, 1c or 1d (1 mmol) in
dry THF (3 mL) was added dropwise to a stirred THF solution of
lithium phenylsulphide (3 mmol) [prepared from benzenethiol
(0.3 mL, 3 mmol) and butyllithium (1.875 mL, 1.6 M solution in
hexane, 3 mmol) in THF (5 mL) at ꢁ78 ꢀC under N2 for 10 min] or
lithium diphenylphosphide (3.5 mmol) [prepared from diphenyl-
phosphane (0.602 mL, 3.5 mmol) and BuLi (2.184 mL, 1.6 M solution
in hexane, 3.5 mmol) in THF (5 mL) at 0 ꢀC under N2 for 30 min]. In
the reactions of 1c with lithium phenylsulphide the mixture was
allowed to warm to room temperature and stirred at that temper-
ature for 24 h. With 1a and 1d the reaction mixture was heated at
reflux of THF till the full consumption of starting materials was
observed by TLC (reaction time for 1a: 20 h; 1d: 22 h). In the re-
actions with lithium diphenylphosphide the mixture was allowed
to warm to room temperature and stirred for 5 days. Quenching
with aqueous ammonium chloride, aqueous work-up with ether,
drying (MgSO4), and chromatography gave the products charac-
terized below.
(450.21) requires C, 71.96; H, 7.83%].
4.4.8. E-1-(Dimethylphenylsilyl)-2-phenylethene (4b). Yield: 192 mg
(81%).22
4.5. Stannylcupration of alkenylphosphane oxides. General
procedure
A solution of a vinylphosphane oxide 1a,c,d (1 mmol) in THF dry
(2 mL) was added to a stirred solution of lithium butyl(tributyl-
stannyl)cuprate (2 mmol) in THF (2 mL) at ꢁ78 ꢀC under N2. The
reaction mixture was stirred at that temperature for 1 h and then
was gradually warmed to 0 ꢀC over 3 h. The mixture was then
hydrolysed with a saturated aqueous NH4Cl solution and extracted
with ether, and the organic layer was dried (MgSO4). The solvent
was evaporated and the residue was chromatographed to give the
compounds characterized below.
4.5.1. (E)-1-Propenyldiphenylphosphane oxide (1g). Yield 159 mg
4.7.1. [2-(Phenylthio)propyl]diphenylphosphane oxide (7a). Yield
(66%)5b
271 mg (77%); Rf (AcOEt) 0.31; IR (CHCl3) 1190 cmꢁ1 1H NMR
;
(300 MHz, CDCl3)
1H), 2.69 (ddd, J¼2.6, 9.6, 15.0 Hz, 1H), 3.58 (m, 1H), 7.24e7.70 (m,
15H); 13C NMR (75 MHz, CDCl3)
21.7, 36.9 (d, J¼65.2 Hz), 38.2,
127.4, 128.6 (d, J¼11.5 Hz), 128.9, 129.0. 130.4 (d, J¼9.2 Hz), 131.7,
d
1.46 (d, J¼6.7 Hz, 3H), 2.44 (dt, J¼15.0, 11.5 Hz,
4.5.2. Allyldiphenylphosphane oxide (5). Yield 77 mg (32%); Rf
(AcOEt) 0.22; IR (CHCl3) 1636, 1178, 925 cmꢁ1; 1H NMR (300 MHz,
d
CDCl3)
d
3.15 (dd, J¼7.5, 15.6 Hz, 2H), 5.15 (m, 2H), 5.67 (m, 1H),

9618
A.M. Gonzalez-Nogal et al. / Tetrahedron 66 (2010) 9610e9619
132.2 (d, J¼98.4 Hz), 134.0; 31P NMR (121 MHz, CDCl3)
d
30.21;
J¼123.5 Hz), 119.4, 127.3, 128.2 (d, J¼9.6 Hz), 129.1, 130.7, 132.4,
133.6 (d, J¼99.6Hz), 134.2, 139.1, 153.2; 31P NMR (121 MHz, CDCl3)
[found: C, 71.32; H, 5. 88. C21H21OPS (352.11) requires C, 71.57; H,
6.01%].
d
19.74; [found: C, 73.48; H, 5.55; N 7.82. C22H19N2OP (358.12) re-
quires C, 73.73; H, 5.34; N 8.03%].
4.7.2. [2-(Dimethylphenylsilyl)-2-(phenylthio)ethyl]diphenylphos-
phane oxide (7b). Yield 297 mg (63%); Rf (AcOEt) 0.51; IR (CHCl3)
4.9.2. 4-Methyl-1-phenyl-3-(diphenylphosphanyl)pyrazole
1262,1190,1116 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
0.45 (s, 3H), 0.46
(s, 3H), 2.57 (m, 2H), 3.09 (ddd, J¼5.6, 7.6, 15.4 Hz, 1H), 7.09e7.62
(m, 20H); 13C NMR (75 MHz, CDCl3)
(10). Yield 39 mg (11%); Rf (AcOEt) 0.57; 1H NMR (300 MHz, CDCl3)
d
2.05 (d, J¼1.2 Hz, 3H), 7.25e7. 82 (m, 16H); 31P NMR (121 MHz,
d
ꢁ4.2, ꢁ3.7, 26.7, 32.4 (d,
CDCl3) d 19.82; [found: C, 73.95; H, 5.13; .N, 7.66. C22H19N2OP
J¼66.5 Hz), 126.1, 127.4, 128.2 (d, J¼11.2 Hz), 128.3, 129.2. 130.1 (d,
(358.12) requires C, 73.73; H, 5.34; N, 7.82%].
J¼9.5 Hz), 131.7, 133.5 (d, J¼99.5 Hz), 134.3, 136.2, 136.6; 31P NMR
(121 MHz, CDCl3)
d 30.13; [found: C, 71.46; H, 6. 44. C28H29OPSSi
4.10. Synthesis of (E)- -hydroxyalkenylphosphane oxides by
b
(472.14) requires C, 71.15; H, 6.18%].
BayliseHillman type reactions from vinylphosphane oxides.
General procedure
4.7.3. [2-Phenyl-2-(phenylthio)ethyl]diphenylphosphane oxide (7c).
Yield 310 mg (75%); Rf(AcOEt) 0.33; IR (CHCl3) 1192 cmꢁ1; 1H NMR
A THF solution of LDA (5.5 mmol) [freshly prepared from di-
isopropylamine (0.77 mL, 5.5 mmol) and BuLi (3.43 mL, 1.6 M so-
lution in hexane, 5.5 mmol) in dry THF (6 mL) at ꢁ20 ꢀC under N2
for 15 min] was added to a stirred solution of the vinylphosphane
oxide 1a,c,d (5 mmol) and isobutyraldehyde (5.5 mmol) in dry THF
(5 mL) at ꢁ78 ꢀC for 1 h. The reaction mixture was allowed to warm
to room temperature and quenched by addition of saturated
aqueous ammonium chloride solution, extracted with ethyl acetate,
and dried (MgSO4). The crude product was chromatographed (SiO2,
AcOEt) to give the following products.
(300 MHz, CDCl3)
d
3.02 (m, 2H), 4.79 (dt, J¼5.5, 9.1 Hz, 1H),
6.92e7.82 (m, 20H); 13C NMR (75 MHz, CDCl3)
d
36.6 (d, J¼67.0 Hz),
46.9, 127.3, 127.5, 127.9, 128.1 (d, J¼11.8 Hz), 128.6, 128.8, 130.5 (d,
J¼8.6 Hz), 131.7, 132.0 (d, J¼93.8 Hz), 132.6, 134.0, 140.1; 31P NMR
(121 MHz, CDCl3)
d 28.72; [found: C, 75.56; H, 5. 33. C26H23OPS
(414.12) requires C, 75.34; H, 5.59%].
4.7.4. 1,2-Bis(diphenylphosphanyl)propane (8a). Yield 421 mg
(95%); Rf (AcOEt) 0.30; IR (CHCl3) 1188 cmꢁ1 1H NMR (300 MHz,
;
CDCl3)
d
1.18 (dd, J¼7.0, 16.9 Hz, 3H), 2.35 (m, 2H), 2.80 (m, 1H),
7.16e7.57 (m, 20H); 13C NMR (75 MHz, CDCl3)
d
13.4, 26.7 (d,
4.10.1. (E)-5-Methyl-3-(diphenylphosphanyl)hex-2-en-4-ol
J¼70.2 Hz), 28.5 (d, J¼69.3 Hz), 128.4 (d, J¼9.9 Hz), 130.4 (d,
(11a). Yield 737 mg (47%); Rf (AcOEt) 0.62; 1H NMR (300 MHz,
J¼9.6 Hz), 131.7, 133.2 (d, J¼98.9 Hz), 133.1 (d, J¼98.2 Hz); 31P NMR
CDCl3)
d
0.59 (d, J¼6.7 Hz, 3H), 1.16 (d, J¼6.7 Hz, 3H), 1.90 (m, 4H),
(121 MHz, CDCl3)
d
31.64 (d, JP,P¼49.8 Hz), 37.91 (d, JP,P¼49.8 Hz);
4.10 (dt, J¼23.7, 10.5 Hz, 1H), 4.97 (d, J¼10.5 Hz, 1H), 6.06 (m, 1H),
[found: C, 73.26; H, 6.19. C27H26O2P2 (444.14) requires C, 72.97; H,
5.90%].
7.29e7.59 (m, 6H), 7.65e7.90 (m, 4H); 31P NMR (121 MHz, CDCl3)
d
38.21; [found: C, 72.75; H, 7.18. C19H23O2P (314.14) requires C,
72.59; H, 7.37%].
4.8. Reaction of the alkenylphosphane oxide 1d with
diphenylphosphane
4.10.2. (E)-1-(Dimethylphenylsilyl)-2-(diphenylphosphanyl)pent-1-
en-3-ol (11b). Yield 1.26 g (58%); Rf (AcOEt) 0.60; IR (CHCl3) 3390,
Diphenylphosphane (2 mmol) was added to a stirred solution of
the 1d (1 mmol) in toluene (5 mL). The mixture was heated to
reflux of toluene until the full consumption of starting materials
was observed by TLC (reaction time: 30 h). The solvent was evap-
orated, and the residue was chromatographed to give the com-
pound characterized below.
1438, 1252, 1158, 1115 cmꢁ1 1H NMR (300 MHz, CDCl3)
; d 0.39 (d,
J¼6.5Hz, 3H), 0.44 (s, 3H), 0.46 (s, 3H), 0.95 (d, J¼6.5 Hz, 3H), 2.01 (m,
1H), 4.09 (dt, J¼22.6, 10.7 Hz, 1H), 4. 53 (d, J¼10.7 Hz, 1H), 6.24 (d,
J¼31.1 Hz, 1H), 7.29e7.83 (m, 15H); 13C NMR (75 MHz, CDCl3)
ꢁ1.2,
d
ꢁ0.7, 19.4, 19.5, 33.3, 81.9 (d, J¼9.7 Hz), 128.0, 128.4 (d, J¼11.7 Hz),
129.4, 131.6 (d, J¼9.3 Hz), 131.9, 133.6 (d, J¼103.0 Hz), 133.7, 137.3,
146.7, 153.5 (d, J¼80.7 Hz);31P NMR (121 MHz, CDCl3)
d 37.57; [found:
4.8.1. 1,2-Bis(diphenylphosphanyl)-1-phenylethane (8b). Yield 329
mg (65%); Rf (AcOEt) 0.15; IR (CHCl3) 1175 cmꢁ1; 1H NMR (300 MHz,
C, 72.03; H, 6.89. C26H31O2PSi (434.18) requires C, 71.86; H, 7.19%].
CDCl3)
d
2.83 (dq, J¼1.5, 11.8 Hz, 1H), 3.17 (ddd, J¼4.7, 6.8, 11.8 Hz,
4.10.3. (E)-1-Phenyl-2-(diphenylphosphanyl)pent-1-en-3-ol
(11c). Yield 1.20 g (64%); Rf (AcOEt) 0.50; IR (CHCl3) 3390, 1438,
1H), 4.28 (dt, J¼11.8, 6.8 Hz, 1H), 6.78e8.08 (m, 25H); 13C NMR
(75 MHz, CDCl3)
d
29.9 (d, J¼69.3 Hz), 39.1 (d, J¼68.2 Hz), 126.8,
1160 cmꢁ1; 1H NMR (300 MHz, CDCl3)
d
0.47 (d, J¼6.5Hz, 3H), 0.99
127.4 (d, J¼9.6 Hz), 128.7, 130.9 (d, J¼9.9 Hz), 131.7, 132.4, 133.7 (d,
(d, J¼6.5 Hz, 3H), 2.04 (m,1H), 4.48 (dt, J¼23.0,10.9 Hz,1H), 4. 47 (d,
J¼99.8 Hz), 133.9 (d, J¼98.5 Hz), 134.5 (d, J¼15.6 Hz); 31P NMR
J¼10.9 Hz,1H), 6.84 (d, J¼22.8 Hz,1H), 7.26e7.95 (m, 15H); 13C NMR
(121 MHz, CDCl3)
d
30.80 (d, JP,P¼46.8 Hz), 36.02 (d, JP,P¼46.8 Hz);
(75 MHz, CDCl3)
d
19.4, 19.5, 33.5 (d, J¼2.3 Hz), 77.5 (d, J¼6.3 Hz),
[found: C, 75.51; H, 5.32. C32H28O2P2 (506.16) requires C, 75.88; H,
5.57%].
128.5 (d, J¼10.5 Hz),132.0 (d, J¼9.7 Hz),132.2 (d, J¼2.5 Hz),133.3 (d,
J¼103.9 Hz), 135.0 (d, J¼19.7 Hz), 137.5 (d, J¼92.0 Hz), 144.1 (d,
J¼12.4 Hz); 31P NMR (121 MHz, CDCl3)
d 38.36; [found: C, 76.83; H,
4.9. 1,3-Dipolar cycloaddition of alkenylphosphane oxides
with N-phenylsydnone
6.82. C24H25O2P (376.16) requires C, 76.58; H, 6.69%].
A mixture of N-phenylsydnone (3 mmol) and the vinyl-
phosphane oxides 1a or 1d (1 mmol) in dry xylene (5 mL) was
stirred at reflux for 70 h. The solvent was evaporated under reduced
pressure and the residue was purified by flash chromatography
giving the following products.
4.11. Synthesis of allenes. General procedure
A solution of the hydroxyphosphane oxide 11b or 11c (3 mmol)
in dry DMF (15 mL) was added to a stirred suspension of sodium
hydride (6 mmol) in dry DMF (10 mL). The reaction mixture was
stirred at 50 ꢀC for 1 h and then hydrolysed with a saturated
aqueous solution of ammonium chloride. The aqueous layer was
extracted with methylene chloride and dried (MgSO4). Solvents
were evaporated under reduced pressure and the crude allenes
4.9.1. 3-Methyl-1-phenyl-4-(diphenylphosphanyl)pyrazole (9). Yield
146 mg (42%); Rf (AcOEt) 0.57; 1H NMR (300 MHz, CDCl3)
d
2.33 (s,
3H), 7.25e7.82 (m, 16H); 13C NMR (75 MHz, CDCl3)
d 13.8, 112.5 (d,

A.M. Gonzalez-Nogal et al. / Tetrahedron 66 (2010) 9610e9619
9619
3471e3474; (c) Bartels, B.; Clayden, J.; Gonzalez Martin, C.; Nelson, A.; Russel,
M. G.; Warren, S. J. Chem. Soc., Perkin Trans. 1 1999, 1807e1822.
7. (a) Brandi, A.; Cannavo, P.; Pietrusiewicz, K. M.; Zablocka, M.; Wieczorek, M. J.
Org. Chem. 1989, 54, 3073e3077; (b) Brandi, A.; Cicchi, S.; Goti, A.; Pie-
trusiewicz, K. M.; Wisniewski, W. Tetrahedron 1990, 46, 7093e7104; (c) Brandi,
A.; Cicchi, S.; Goti, A.; Pietrusiewicz, K. M.; Zablocka, M.; Wisniewski, W. J. Org.
Chem. 1991, 56, 4383e4388.
were purified by flash chromatography (SiO2, hexane) to afford the
following products.
4.11.1. 1-(Dimethylphenylsilyl)-4-methylpenta-1,2-diene (12a). Yield
396 mg (57%); Rf (hexane) 0.61; IR (CHCl3) 1958, 1252, 1115 cmꢁ1
;
1H NMR (300 MHz, CDCl3)
J¼4.0 Hz, 6H), 2.15 (m, 1H), 5.76 (d, J¼17.9, 1H), 6.15 (dd, J¼17.9,
6.6 Hz, 1H), 7.20e7.68 (m, 5H); 13C NMR (75 MHz, CDCl3)
d 0.09 (s, 3H), 0.33 (s, 3H), 1.55 (d,
8. Fox, D. J.; Medlock, J. A.; Vosser, R.; Warren, S. J. Chem. Soc., Perkin Trans. 1 2001,
2240e2249.
9. (a) Pietrusiewicz, K. M.; Zablocka, M.; Monkiewicz, J. J. Org. Chem. 1984, 49,
1522e1526; (b) Baldwin, I. C.; Beckett, R. P.; Williams, J. M. J. Synthesis 1996,
34e36; (c) Afarinkia, K.; Binch, H. M.; Modi, C. Tetrahedron Lett. 1998, 39,
7419e7422.
10. Fleming, I.; Gil, S.; Sarkar, A. K.; Schmidlin, T. J. Chem. Soc., Perkin Trans. 1 1992,
3351e3361.
d
ꢁ2.2,
22.4, 22.5, 28.5, 83.2, 101.8, 127.5, 129.3, 134.0, 138.6, 210.7; [found:
C, 77.69; H, 10.27. C15H24Si (232.16) requires C, 77.51; H, 10.41%].
4.11.2. 4-Methyl-l-phenylpenta-1,2-diene(12b). Yield 339 mg (65%).24
11. The tert-butyldiphenylsilyl group has higher migratory aptitude than its dime-
thylphenylsilyl counterpart because phenyl groups on silicon have been shown to
accelerate the Brook rearrangement[Brook, A. G.; LeGrow, G. E.; McRae, D. M. Can.
J. Chem. 1967, 45, 239e245].
Acknowledgements
12. The exclusive formation the one diastereoisomer was proved by 31P NMR. A
single signal for the phosphorus was detected in the crude reaction mixture.
13. The structural assignation of the major regioisomer 9 was possible by 13C NMR
spectroscopy. The phosphanyl group should be attached at C-4 because this
We thank the Spanish Ministerio de Ciencia y Tecnologia
(MCYT) for supporting this work.
signal at
d
¼112.5 ppm is a doublet with a coupling constant JC/P¼123.5 Hz.
14. (a) Elding, L. J.; Kellenberger, B.; Venanzi, L. M. Helv. Chim. Acta 1983, 66,
1676e1690; (b) Johnson, C. R.; Imamoto, R. J. Org. Chem. 1987, 52, 2170e2174;
(c) McKinstry, L.; Livinghouse, T. Tetrahedron 1994, 50, 6145e6154; (d) Yano, T.;
Hoshimo, M.; Kuroboshi, M.; Tanaka, H. Synlett 2010, 801e803.
Supplementary data
Supplementary data associated with this article can be found in
the online version at doi:10.1016/j.tet.2010.10.016.
15. (a) Field, J. S.; Haines, R. J.; Lakoba, E. I.; Sosabowski, M. H. J. Chem. Soc., Perkin
Trans. 1 2001, 3352e3360; (b) Myrex, R. D.; Colbert, C. S.; Gray, G. M.; Duffey, C.
H. Organometallics 2004, 23, 409e415.
16. (a) Schuster, H. F.; Coppola, G. M. Allenes in Organic Synthesis; John Wiley: New
York, NY, 1988; (b) Krause, N.; Hashmi, A. S. K. Modern Allene Chemistry;
Wiley-VCH: Weinhein, 2004; Vol. 12; (c) Ma, S. Chem. Rev. 2005, 105,
2829e2871.
17. Our research group has studied the silyl- and stannyl-cupration of silylallenes
obtaining disilyl and silylstannylalkenes bearing different silyl or stannyl group
in allyl and vinyl moieties. The selective electrophilic substitution of the allyl-
silane or stannane unit in the presence of vinylsilane or vinylstannane unit was
proved. This result will be reported as soon as possible.
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