Regio- and stereospecific cleavage of stannyloxiranes with lithium diphenylphosphide

Article abstract of DOI:10.1002/ejoc.200800984

Unsubstituted or C-substituted stannyloxiranes reacted stereospecifically with lithium diphenylphosphide to give either β-hydroxyphosphane oxides resulting from α-opening or β-phosphanyl ketones by β-opening. Furthermore, the reactivities of distannyloxir

Full text of DOI:10.1002/ejoc.200800984

FULL PAPER
DOI: 10.1002/ejoc.200800984
Regio- and Stereospecific Cleavage of Stannyloxiranes with Lithium
Diphenylphosphide
Ana M. González-Nogal,*[a] Purificación Cuadrado,[a] and M. Angeles Sarmentero[a]
Keywords: Stannanes / Cleavage reactions / Phosphorylation / Phosphane oxides / Silyl enol ethers
Unsubstituted or C-substituted stannyloxiranes reacted
stereospecifically with lithium diphenylphosphide to give
either β-hydroxyphosphane oxides resulting from α-opening
tin group and, depending on the nature of the silyl group,
led either to stereodefined β-silylated vinylphosphane oxides
or to β-stannyl silyl enol ethers. Finally, the gem-silyl-stann-
or β-phosphanyl ketones by β-opening. Furthermore, the re- yloxiranes underwent β-opening to give mixtures of β-phos-
activities of distannyloxiranes depend on their configura-
tions. The cis isomers afforded the corresponding α,β-diphos-
phanyl alcohols, while the trans isomers were shown to be
unreactive. On the other hand, the regiochemistry of the
ring-opening from β-silyl-stannyloxiranes is controlled by the
phanyl acylsilanes and silyl enol ethers. All compounds are
interesting synthons of great versatility in organic chemistry.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
thetic possibilities of the cleavage of metallated epoxides by
lithium diphenylphosphide, we have extended this method-
ology to stannylated epoxides.
Introduction
Whereas the behaviour of epoxysilanes toward nucleo-
philic reagents has been widely studied,[1] there are few ref-
erences relating to the reactivity of stannyloxiranes. We have
only found reports of their conversion into ketones[2] by
cleavage with formic acid and subsequent treatment with
lithium hydroxide in aqueous THF, their transformation
into olefins[3] by reductive alkylation with alkyllithium rea-
gents, ring-opening with metal hydrides[4] or organocup-
rates[5] and transmetallation with an organolithium spe-
cies.[6]
The natures of the products obtained from the reactions
of stannyloxiranes with lithium diphenylphosphide depend
on the substitution type of the oxirane ring. We therefore
started from unsubstituted and from C-, Si- and Sn-substi-
tuted stannyloxiranes. In general, these substrates were syn-
thesised by epoxidation of the corresponding vinylstann-
anes previously obtained by tributylstannyl cupration from
alkynes[10] or allenes.[11]
In a previous paper we described the regio- and stereo-
specific cleavage of stannyloxiranes with lithium phenylsul-
fide,[7] which showed behaviour different from that observed
in the cleavage of silylepoxides with this same reagent.[8]
Moreover, we have also reported[9] the reaction behaviour
of differently substituted silyl- and disilylepoxides toward
lithium diphenylphosphide. Using unsubstituted or α- and
β-C-substituted silylepoxides, we have synthesised vinyl-
phosphonium iodides or vinylphosphane oxides by α-open-
ing and silyl enol ethers, vinylsilanes or α-hydroxysilanes by
β-opening. On the other hand, α,β- or α,α-disilylepoxides
afforded β-silyl vinylphosphane oxides or α-silylated silyl
enol ethers by α- and β-cleavage, respectively. In view of the
different behaviour of silyl- and stannyloxiranes toward the
nucleophilic attack and with the aim of increasing the syn-
Results and Discussion
On treatment at 0 °C with lithium diphenylphosphide,
followed by hydrolysis with saturated aqueous sodium hy-
drogen carbonate, the α-unsubstituted stannyloxiranes 1a–d
afforded the β-hydroxyphosphane oxides 2a–d (Scheme 1).
When the hydrolysis was carried out in an acid medium
(saturated aqueous solution of ammonium chloride), how-
ever, the initially formed β-hydroxyphosphane oxides were
partially dehydrated to give minor amounts of the more
stable trans-vinylphosphane oxides 3a–d (10–15%), inde-
pendently of the starting stannyloxirane configuration.
The lack of stereospecificity observed in the synthesis of
vinylphosphane oxides 3a–d indicates that their formation
was different from that described for the α-opening of the
corresponding epoxysilanes[9] with the same reagent, in
which the alkoxysilane intermediates afforded stereodefined
vinylphosphane oxides by Peterson syn-elimination. In this
case, the evolution of the β-stannylalkoxide intermediate A
(Scheme 2) generated by α-opening could take place by 1,3-
migration of the stannyl group from carbon to oxygen and
[a] Departamento de Química Orgánica, Facultad de Ciencias and
Centro de Innovación en Química y Materiales Avanzados
(CINQUIMA), Universidad de Valladolid,
47011 Valladolid, Spain
Fax: +34-983-423013
E-mail: agn@qo.uva.es
850
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Eur. J. Org. Chem. 2009, 850–859

Cleavage of Stannyloxiranes with Ph2PLi
Scheme 3.
Scheme 4.
Scheme 1.
sis,[12] could be of interest in the synthesis of heterocycles.
We acylated these substrates with the goal of preparing
phosphanyl-substituted isoxazoles and pyrazoles by treat-
ment of the resulting 2-phosphanyl-substituted 1,3-dike-
tones with hydroxylamine and methylhydrazine.
hydrolysis of the resulting stannyl ether to give the β-hy-
droxyphosphane oxides 2a–d, which in an acidic medium
could experience partial dehydration to yield trans-vinyl-
phosphane oxides 3a–d.
The irreversible condensation of the β-phosphanyl
ketones 4a and 4c with acetyl and benzoyl chloride in the
presence of NaH afforded the necessary 2-phosphanyl-sub-
stituted 1,3-diketones 5a–c in good yields (Scheme 5).
Scheme 5.
Unfortunately, the synthesis of phosphanyl-substituted
isoxazoles and pyrazoles did not take place. When we
Scheme 2.
On treatment with lithium diphenylphosphide treated 5a–c with hydroxylamine or methyl hydrazine the α-
(1.5 equiv.) at room temperature, the α-C-substituted β-un- phosphanyl ketones 4a and 4c resulting from retroaldoli-
substituted stannyloxiranes 1e–g gave β-phosphanyl ketones sation were obtained. In the reactions with hydroxylamine,
4a–c (Scheme 3).
together with the ketone 4c, the corresponding oxime 6c
The α-C-substituent increases the steric impedance in was isolated (Scheme 6).
this position, so the nucleophilic attack consequently takes
In contrast, we were able to synthesise 2-phosphanyl-2H-
place exclusively at β-C. This behaviour is analogous to that azirines from the tosyloximes 7a–c – derived from phos-
observed in the opening of α-C-substituted epoxysilanes in phorylated ketones 4a–c – by cyclisation in a basic medium
the presence of the same reagent,[9b] but the evolution of (Neber reaction). Treatment of the tosyloxime 7a with tri-
the intermediate resulting from the β-opening is different. ethylamine at 0 °C led in good yield to 2-(diphenylphos-
In this case, the unstable β-diphenylphosphanyl-α-oxido- phanyl)-3-methyl-2H-azirine (8, Scheme 7).
stannane intermediate B (Scheme 4) is converted into a car-
These highly strained heterocycles are very useful inter-
bonyl group by elimination of the stannyl group.
mediates in organic synthesis because of their versatile ther-
These α-phosphanyl ketones, besides finding widespread mal and photochemical behaviour,[13,14] as well as their high
application as hemilabile ligands in homogeneous cataly- reactivities toward nucleophilic and electrophilic rea-
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A. M. González-Nogal, P. Cuadrado, M. A. Sarmentero
FULL PAPER
cally give the vinylphosphane oxides 3e and 3f. On the other
hand, the formation of anti-2e should take place through
inversion in the configuration of the carbanion resulting
from the tin migration from carbon to oxygen in the cited
intermediate C. Likewise, the formation of the vinylphos-
phane oxides 3e and 3f could occur by anti-elimination of
water from the previously obtained alcohols (Scheme 9).
Scheme 6.
Scheme 9.
The cis- and trans-2,3-distannyloxiranes 1j and 1k
showed very different reactivities toward lithium diphenyl-
phosphide. The cis-2,3-bis(tributylstannyl)oxirane 1j re-
acted at 0 °C with lithium diphenylphosphide (2.5 equiv.) to
give the 1,2-bis(diphenylphosphanyl)ethanol 9 (Scheme 10),
a useful tridentate ligand, whereas under the same condi-
tions the trans-2,3-bis(tributylstannyl)oxirane 1k was reco-
vered.
Scheme 7.
gents.[15] 2-Functionalised 2H-azirines are also established
as building blocks for the synthesis of a range of hetero-
cyclic compounds.[16]
On the other hand, the α- and β-alkyl- or -phenyl-substi-
tuted stannyloxiranes 1h and 1i underwent α-opening to
give the β-hydroxyphosphane oxide 2e and/or the vinyl-
phosphane oxides 3e and 3f stereospecifically (Scheme 8).
Scheme 10.
Scheme 8.
Compound 2e, which was isolated as one diastereoisomer
The reaction product 9 could be explained by supposing
(a single signal appears in the 31P NMR spectrum), is stabi- initial nucleophilic attack at one of the heterocyclic carbons
lised by intramolecular hydrogen bonds between the hy- and the formation of the intermediate D (Scheme 11),
droxy and phosphanyl groups[17] and has an anti configura- which would evolve into aldehyde E through elimination of
tion.[18]
the stannyl group. Nucleophilic addition of the diphenyl-
The substitution at α and β once again determined that phosphide to this aldehyde would give rise to the β-oxido-
the stannyl group controlled the regiochemistry. The α- stannane F, which would experience a 1,3-migration of the
opening should afford a β-oxidostannane intermediate C, tin group from carbon to oxygen to afford, after hydrolysis,
which on Bu3SnOLi syn-elimination would stereospecifi- the diphosphanyl alcohol 9.
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Cleavage of Stannyloxiranes with Ph2PLi
Scheme 13.
Scheme 11.
The behaviour of the cis-2-silyl-3-stannyloxiranes 1n and
1o is different from that indicated for their trans analogues.
In this case, the reactions were regiospecific. Although in
both silylstannyloxiranes 1n and 1o the attack of the lithium
diphenylphosphide occurred exclusively at α-C to the stann-
yl group, the evolution of the resulting intermediate was
different, depending on the nature of the silyl group. The
(dimethylphenylsilyl)-stannyloxirane 1n gave the cis-β-(di-
methylphenylsilyl)-substituted vinylphosphane oxide 3j,
whereas the (tert-butyldiphenylsilyl)-stannyloxirane 1o af-
forded the trans-β-tributylstannyl tert-butyldiphenylsilyl
enol ether 10a (Scheme 14).
We also studied the behaviour of silylated stannyloxir-
anes in the presence of lithium diphenylphosphide with the
aim of establishing which of the two metallated groups
would control the regiochemistry of the ring opening. We
started from different silylated cis- and trans-2-silyl-3-stann-
yloxiranes and 2-silyl-2-stannyloxiranes and established that
their reactivities depend on the nature of the silyl group and
the relative position and configuration of both metallated
groups.
The trans-(tributylstannyl)-silyloxiranes 1l and 1m re-
acted with lithium diphenylphosphide to give mixtures of
the corresponding β-silyl- and β-stannyl-substituted vinyl-
phosphane oxides 3g–i (Scheme 12).
Scheme 14.
The exclusive attack of the diphenylphosphide anion at
α-C to the tin group and β to the silyl group in the case of
the cis-(tert-butyldiphenylsilyl)oxirane 1o is predictable in
view of the preference previously described for these ring
Scheme 12.
It can be postulated that the stereospecific formation of openings in the trans-silyl-stannyloxiranes 1l and 1m. In this
the trans-β-silylvinylphosphanes 3g and 3i takes place case, this difference is increased by the presence of the bulky
through nucleophilic attack at α-C to the stannyl group tert-butyldiphenylsilyl group, which guides the β-opening
to give the β-silyl-β-oxidostannane intermediate
G
process.[9] However, the different behaviour of the cis- and
(Scheme 13), followed by syn-elimination of Bu3SnOLi. The trans-(dimethylphenylsilyl)oxiranes 1m and 1n is less evi-
different behaviour shown by the intermediate G with re- dent. Probably, the exclusive nucleophilic attack at α-C to
spect to the β-oxidostannanes A, C and F, which experi- the stannyl group in the cis-epoxide 1n, followed by Bu3-
enced 1,3-migration of the tin group from carbon to oxy- SnOLi syn-elimination in the intermediate I to give the vi-
gen, could be due to the presence of the silyl group, which nylphosphane oxide 3j, would be due to steric requirements
would destabilise the hypothetical β-carbanion. On the (the tributylstannyl and diphenylphosphanyl groups were
other hand, the nucleophilic attack at α-C to the silyl group eclipsed) of the necessary conformation for the Peterson eli-
afforded the β-stannyl-β-oxidosilane H, which underwent mination in the intermediate resulting from the α-opening
Peterson syn-elimination to give the trans-β-stannylvi- with respect to the silicon. When the silyl group was the
nylphosphane 3h (Scheme 13). The preference for α-open- bulky tert-butyldiphenyl system, the intermediate J re-
ing with respect to the tributyltin group is increased when sulting from α-opening to the tin group of the silyl-stann-
the silyl group is bulkier.
yloxirane 1o underwent Brook rearrangement and anti-eli-
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853

A. M. González-Nogal, P. Cuadrado, M. A. Sarmentero
FULL PAPER
mination of diphenylphosphide to give the β-stannyl silyl
The steric hindrance at α-C of the gem-silyl-stannyloxir-
enol ether 10a, with E configuration, stereospecifically ane 1p induces β-opening to give exclusively an α-silyl-α-
(Scheme 15).
stannyloxide intermediate K, which, out of the different
possibilities of evolution (Brook rearrangement, Wittig eli-
mination or tin elimination), preferred conversion into the
acylsilane 4d through elimination of the tributylstannyl-
lithium. This basic compound probably induces the iso-
merisation of the initially formed acylsilane into the silyl
enol ether 10b through enolisation and tert-butyldiphenyl-
silyl migration from carbon to oxygen (Scheme 17).
Scheme 17.
Scheme 15.
The different behaviour of the intermediates I and J
could depend on two factors: a) higher migratory aptitude
of the tert-butyldiphenylsilyl group than its dimethylphen-
ylsilyl counterpart (phenyl groups on silicon have been
shown[19] to accelerate the Brook rearrangement), and b) in-
stability of the necessary conformation for the Bu3SnOLi
syn-elimination in the intermediate J in which the bulky
diphenylphosphanyl and tert-butyldiphenylsilyl groups
should be eclipsed, whereas in the conformation for Brook
rearrangement and anti-elimination the tert-butyldiphenyl-
silyl and stannyl groups are staggered.
The synthesis of gem-silyl-stannyloxiranes from unsubsti-
tuted silyloxiranes by deprotonation at low temperature and
trapping with chlorostannanes was examined, but only the
oxiranyl anion resulting from deprotonation of the (tert-
butyldiphenylsilyl)-epoxyethane was sufficiently stable to be
trapped at –60 °C by the tributylstannyl chloride. We were
therefore only able to obtain 2-(tributylstannyl)-2-(tert-
butyldiphenylsilyl)oxirane (1p) (Scheme 16).
Conclusions
In summary, the stannyl group exercises a strong direct-
ing effect in the opening of stannyloxiranes. In general, α-
opening took place except when the α-position was hin-
dered. This regiochemistry is analogous to that described
for the corresponding epoxysilanes. Nevertheless, the evol-
ution of the resulting intermediates is very different, giving
rise to other products. If the stannyloxirane bears a silyl
group, the regiochemistry and evolution of the reaction is
governed by the tin group. The α-attack of the diphenyl-
phosphide anion on stannyloxiranes has allowed us to syn-
thesise β-phosphanyl alcohols. The easy conversion of
phosphane oxides into phosphanes[20] makes these com-
pounds interesting precursors of chiral 1,2-donor bidentate
ligands for transition-metal-catalysed asymmetric synthe-
sis.[21] These hemilabile ligands have also encountered suc-
cess with applications in small-molecule activation, small-
molecule sensing and stabilisation of transition com-
plexes.[22]
On the other hand, the β-phosphanyl ketones obtained
by β-opening of α-substituted stannyloxiranes, besides be-
ing σ-donor/π-acceptor ligands,[12] are interesting interme-
diates for the synthesis of three-membered phosphanyl het-
erocycles with potential biological activity.[23] Moreover, the
β-stannyl- and β-phosphanyl silyl enol ethers 10a and 10b
and the β-phosphanylacylsilane 4d resulting from opening
of (tert-butyldiphenylsilyl)-stannyloxiranes are very versa-
tile small synthons. The vinylstannane unit in 10a is useful
in Stille coupling,[24] as a vinyl anion equivalent[25] and in
electrophilic ipso-substitution[7,26] or rhodium-catalysed
conjugate addition processes,[27] and the phosphanyl group
Scheme 16.
Treatment of 1p with lithium diphenylphosphide increases the interest of 10b. It is known that phosphorus
(1.5 equiv.) afforded a mixture of the β-phosphorylated silyl substituents regulate many biological functions.[28] Further-
enol ether 10b and the acylsilane 4d.
more, compound 7, besides being a generator of stabilised
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Cleavage of Stannyloxiranes with Ph2PLi
CDCl3): δ = 9.5, 13.6, 13.9, 22.6, 27.2, 28.9, 34.1, 53.3, 55.9 ppm.
C18H38OSn (390.19): calcd. C 55.55, H 9.84; found C 55.83, H
10.22.
carbanions (phosphorus ylide vs. enolate anion), has a spe-
cial reactivity conferred on it by the acylsilane unit. Acylsil-
anes are valuable building blocks for the synthesis of com-
plex products.[29] Among their many interesting applica-
tions, acylsilanes can be regarded as aldehyde equivalents
in stereocontrolled nucleophilic acylation.[30] Finally, the
presence of the β-silyl or stannyl groups in the metallated
vinylphosphane oxides obtained by opening of silylstan-
nyloxiranes should increase the versatility of these sub-
strates. Some applications of the vinylphosphane oxides –
including as Michael acceptors and as dipolarophiles in 1,3-
dipolar cycloadditions – will be published as soon as pos-
sible.
2-(Tributylstannyl)-1,2-epoxypropane (1e): Yield 1.4 g (70%). Rf =
0.39 (hexanes). 1H NMR (300 MHz, CDCl3): δ = 0.90 (t, J =
7.2 Hz, 9 H), 0.90 (m, 6 H), 1.31 (m, 6 H), 1.39 (s, 3 H), 1.54 (m,
6 H), 2.50 (d, J = 5.2 Hz, 1 H), 2.65 (d, J = 5.2 Hz, 1 H) ppm.
13C NMR (75 MHz, CDCl3): δ = 8.5, 13.5, 25.9, 27.3, 28.9, 51.9,
53.1 ppm. C15H32OSn (348.15): calcd. C 51.90, H 9.29; found C
51.55, H 9.68.
2-(Tributylstannyl)-1,2-epoxyhexane (1f): Yield 1.7 g (72%). Rf =
1
0.40 (hexanes). H NMR (300 MHz, CDCl3): δ = 0.90 (m, 18 H),
1.31 (m, 10 H), 1.54 (m, 8 H), 2.51 (d, J = 5.0 Hz, 1 H), 2.61 (d, J
= 5.0 Hz, 1 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 8.6, 8.9,
13.6, 13.9, 22.8, 27.3, 29.0, 40.1, 50.9, 57.8 ppm. C18H38OSn
(390.19): calcd. C 55.55, H 9.84; found C 55.17, H 9.51.
Experimental Section
1-(Tributylstannyl)-1-phenylepoxyethane (1g): Yield 1.8 g (73%). Rf
= 0.42 (hexanes). 1H NMR (300 MHz, CDCl3): δ = 0.91 (t, J =
7.2 Hz, 9 H), 0.97 (m, 6 H), 1.36 (m, 6 H), 1.56 (m, 6 H), 2.75 (d,
J = 5.9 Hz, 1 H), 2.96 (d, J = 5.9 Hz, 1 H), 7.26–7.37 (m, 5 H) ppm.
C20H34OSn (410.16): calcd. C 58.70, H 8.38; found C 59.04, H 7.96.
General: THF was distilled from sodium benzophenone ketyl in a
recycling still. All chromatographic and workup solvents were dis-
tilled prior to use. All reactions involving organometallic reagents
were carried out under nitrogen. 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 precoated
plates (silica gel 60, nano-SIL-20, Macherey–Nagel). Flash
chromatography was performed on silica gel 60 (230–400 mesh, M–
N). In general, the starting stannyloxiranes were prepared by epox-
idation of the corresponding vinylstannanes, obtained by treatment
of the intermediates resulting from tributylstannyl cupration of al-
kynes[10] 1a–d and 1f–n or allenes[11] like 1e with electrophiles, ex-
cept for the 2,2-silyl-stannyloxirane 1o, which was obtained by
treatment of the oxiranyl anion produced from the corresponding
silyl epoxide and BuLi in the presence of TMEDA with ClSnBu3.
(E)-5-(Tributylstannyl)-5,6-epoxydecane (1h): Yield 1.9 g (71%). Rf
1
= 0.46 (hexanes). H NMR (300 MHz, CDCl3): δ = 0.80–1.00 (m,
25 H) 1.25–1.50 (m, 20 H), 2.77 (t, J = 5.9 Hz, 1 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 8.6, 9.0, 13.5, 13.9, 22.6, 27.3, 29.0,
33.9, 60.8, 63.8 ppm. C22H46OSn (446.26): calcd. C 59.34, H 10.41;
found C 58.96, H 10.79.
(E)-1,2-Diphenyl-1-(tributylstannyl)epoxyethane (1i): Yield 2.1 g
(75%). Rf = 0.51 (hexanes). 1H NMR (300 MHz, CDCl3 ): δ = 0.81
(t, J = 7.1 Hz, 9 H), 1.57–1.11 (m, 18 H), 3.91 (s, 1 H), 7.18–7.43
(m, 10 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 10.3, 13.5, 27.2,
28.7, 64.5, 69.9, 125.3, 125.7, 126.1, 126.8, 127.3, 127.9, 128.3,
138.6, 144.7 ppm. C26H38OSn (486.19): calcd. C 64.35, H 7.89;
found C 64.71, H 8.06.
Synthesis of Epoxystannanes
Method A. Typical Procedure: MCPBA (8.1 mmol) and NaHCO3
(12 mmol) were added to a solution of stannylalkene (6 mmol)
either in CH2Cl2 (20 mL) or, when (tert-butyldiphenylsilyl)-stannyl-
substituted alkenes were used, in CHCl3 (20 mL). The reaction
mixture was stirred at room temperature in CH2Cl2 or at reflux in
CHCl3 until TLC indicated complete reaction (reaction time 0.5–
5 h.). The mixture was washed with a saturated aqueous solution
of NaHSO3, NaHCO3 and NaCl. The organic layer was dried
(MgSO4), the solvent was removed, and the residue was chromato-
graphed (silica gel, hexane/AcOEt) to provide the following prod-
ucts.
cis-1,2-Bis(tributylstannyl)epoxyethane (1j): Yield 2.2 g (60%). Rf =
0.59 (hexanes). 1H NMR (300 MHz, CDCl3): δ = 0.90 (t, J =
7.1 Hz, 18 H), 0.92 (m, 12 H), 1.33 (m, 12 H), 1.54 (m, 12 H), 2.60
(s, 2 H) ppm. C26H56OSn2 (624.24): calcd. C 50.19, H 9.07; found
C 49.73, H 8.67.
trans-1,2-Bis(tributylstannyl)epoxyethane (1k): Yield 2.3 g (65%).
1
Rf = 0.61 (hexanes). H NMR (300 MHz, CDCl3 ): δ = 0.91 (t, J
= 7.0 Hz, 18 H), 0.93 (m, 12 H), 1.36 (m, 12 H), 1.60 (m, 12 H),
2.62 (s, 2 H) ppm. C26H56OSn2 (624.24): calcd. C 50.19, H 9.07;
found C 50.41, H 9.25.
(Tributylstannyl)epoxyethane (1a): Yield 1.5 g (72%); see ref.[5]
trans-1-(Tributylstannyl)-2-(trimethylsilyl)epoxyethane (1l): Yield
1.9 g (80%). Rf = 0.47 (hexanes). H NMR (300 MHz, CDCl3): δ
= 0.05 (s, 6 H), 0.90 (t, J = 7.3 Hz, 9 H), 0.92 (m, 6 H), 1.50 (m,
6 H), 1.53 (m, 6 H), 2.10 (d, J = 5.2 Hz, 1 H), 2.55 (d, J = 5.2 Hz,
1
trans-1-Phenyl-2-(tributylstannyl)epoxyethane (1b): Yield 2.1 g
(85%); see ref.[31]
cis-1-(Tributylstannyl)-1,2-epoxypropane (1c): Yield 1.6 g (79%). Rf 1 H) ppm. 13C NMR (75 MHz, CDCl3): δ = –3.8, 8.6, 13.6, 27.3,
= 0.39 (hexanes). 1H NMR (300 MHz, CDCl3): δ = 0.90 (t, J = 29.0, 47.4, 48.2 ppm. MS (EI, 70 eV): m/z (%) = 349 (5) [M – Bu]
7.3 Hz, 9 H), 1.00 (m, 6 H), 1.27 (d, J = 5.2 Hz, 3 H), 1.35 (m, 6
+, 177 (77), 121 (65). C17H38OSiSn (406.17): calcd. C 50.38, H 9.45;
H), 1.55 (m, 6 H), 2.75 (d, J = 5.2 Hz, 1 H), 3.23 (quint, J = 5.2 Hz, found C 50.72, H 9.81.
1 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 9.5, 13.6, 19.5, 27.3,
30.0, 51.5, 53.8 ppm. MS (EI, 70 eV): m/z (%) = 291 (5) [M –
Bu]+, 269 (3), 177 (100), 121 (75). C15H32OSn (348.15): calcd. C
51.90, H 9.29; found C 52.30, H 8.91.
trans-1-(Tributylstannyl)-2-(dimethylphenylsilyl)epoxyethane (1m):
Yield 2.1 g (76%). Rf = 0.45 (hexanes). 1H NMR (300 MHz,
CDCl3): δ = 0.37 (s, 3 H), 0.43 (s, 3 H), 0.96 (t, J = 7.3 Hz, 9 H),
0.96 (m, 6 H), 1.39 (m, 6 H), 1.56 (m, 6 H), 2.37 (d, J = 5.2 Hz, 1
H), 2.67 (d, J = 5.2 Hz, 1 H), 7.41–7.45 (m, 3 H), 7.62–7.65 (m, 2
H) ppm. 13C NMR (75 MHz, CDCl3): δ = –5.2, 8.7, 13.7, 27.3,
cis-1-(Tributylstannyl)-1,2-epoxyhexane (1d): Yield 1.7 g (75%). Rf
1
= 0.40 (hexanes). H NMR (300 MHz, CDCl3): δ = 0.83–0.98 (m,
18 H), 1.26–1.36 (m, 10 H), 1.39–1.58 (m, 8 H), 2.76 (d, J = 4.7 Hz, 29.0, 46.8, 48.2, 127.8, 129.3, 133.9, 136.6 ppm. C22H40OSiSn
1 H), 3.11 (dt, J = 4.7, 6.8 Hz, 1 H) ppm. 13C NMR (75 MHz,
(468.19): calcd. C 56.54, H 8.63; found C 56.91, H 9.03.
Eur. J. Org. Chem. 2009, 850–859
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
855

A. M. González-Nogal, P. Cuadrado, M. A. Sarmentero
FULL PAPER
cis-1-(Tributylstannyl)-2-(dimethylphenylsilyl)epoxyethane
(1n): (m, 15 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 39.1 (d, J =
Yield 1.8 g (67%). Rf = 0.44 (hexanes). 1H NMR (300 MHz,
CDCl3): δ = 0.35 (s, 6 H), 0.89 (t, J = 7.2 Hz, 9 H), 0.90 (m, 6 H),
1.31 (m, 6 H), 1.46 (m, 6 H), 2.70 (d, J = 6.4 Hz, 1 H), 2.98 (d, J
= 6.4 Hz, 1 H), 7.37–7.40 (m, 3 H), 7.59–7.62 (m, 2 H) ppm. 13C
68.6 Hz), 68.9 (d, J = 7.5 Hz), 125.3, 128.4, 129.8, 130.5, 131.2,
132.7, 133.9 (d, J = 95.2 Hz), 143.8 (d, J = 13.0 Hz) ppm. 31P NMR
(121 MHz, CDCl ): δ = 34.52 ppm. IR (CHCl ): ν = 3365, 1439,
˜
3
3
1172 cm–1. C20H19O2P (322.11): calcd. C 74.52, H 5.94; found C
NMR (75 MHz, CDCl3): δ = –4.1, –3.6, 9.5, 13.7, 27.3, 29.0, 48.5, 74.81, H 6.24.
51.3, 127.9, 129.4, 133.1, 136.9 ppm. C22H40OSiSn (468.19): calcd.
C 56.54, H 8.63; found C 56.16, H 8.20.
1-(Diphenylphosphanyl)propan-2-ol (2c): Yield 195 mg (75%). Rf =
0.25 (AcOEt); m.p. 200–205 °C (from hexane/AcOEt). 1H NMR
(300 MHz, CDCl3): δ = 1.28 (dd, J = 6.1, 1.5 Hz, 3 H), 2.36 (ddd,
J = 14.9, 7.6, 2.4 Hz, 1 H), 2.49 (ddd, J = 14.9, 11.7, 9.8 Hz, 1 H),
4.24 (m, 1 H), 4.59 (br. s, 1 H), 7.30–7.92 (m, 10 H) ppm. 13C NMR
cis-1-(Tributylstannyl)-2-(tert-butyldiphenylsilyl)epoxyethane (1o):
Yield 1.7 g (63%). Rf = 0.43 (hexanes). 1H NMR (300 MHz,
CDCl3): δ = 0.80 (t, J = 7.2 Hz, 9 H), 0.98–0.86 (m, 6 H), 1.10 (s,
9 H), 1.40–1.12 (m, 12 H), 3.15 (d, J = 6.5 Hz, 1 H), 3.18 (d, J = (75 MHz, CDCl3): δ = 24.8 (d, J = 14.4 Hz), 37.9 (d, J = 71.0 Hz),
6.5 Hz, 1 H), 7.32–7.46 (m, 6 H), 7.74–7.81 (m, 4 H) ppm. 13C 63.2 (d, J = 4.7 Hz), 128.7 (d, J = 11.8 Hz), 130.9 (d, J = 9.3 Hz),
NMR (75 MHz, CDCl3): δ = 9.6, 13.5, 18.9, 27.1, 27.4, 28.7, 45.7, 132.0, 133.1 (d, J = 99.2 Hz) ppm. 31P NMR (121 MHz, CDCl3):
50.8, 127.5, 127.8, 129.5, 131.0, 133.1, 135.9, 136.4 ppm. C30H48O-
SiSn (572.25): calcd. C 63.05, H 8.47; found C 63.37, H 8.45.
δ = 34.71 ppm. IR (CHCl3): ν˜ = 3383, 1437, 1170 cm–1. C15H17O2P
(260.10): calcd. C 69.22, H 6.58; found C 68.96, H 6.89.
1-(Diphenylphosphanyl)hexan-2-ol (2d): Yield 223 mg (74%). Rf =
0.31 (AcOEt). 1H NMR (300 MHz, CDCl3): δ = 0.90 (t, J = 7.3 Hz,
3 H), 1.38 (m, 4 H), 1.50 (m, 2 H), 2.45 (m, 2 H), 2.85 (br. s, 1 H),
4.03 (m, 1 H), 7.35–7.52 (m, 6 H), 7.64–778 (m, 4 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 13.9, 22.4, 27.3, 36.2 (d, J = 71.4 Hz),
38.3 (d, J = 13.2 Hz), 66.8 (d, J = 4.9 Hz), 127.5 (d, J = 13.1 Hz),
131.2 (d, J = 9.0 Hz) 132.7, 134.0 (d, J = 98.5 Hz) ppm. 31P NMR
Method B.
– Synthesis of 1-(tert-Butyldiphenylsilyl)-1-(tributyl-
stannyl)epoxyethane (1p): BuLi (7.2 mmol, 1.6  in hexane, 4.5 mL)
and TMEDA (1.08 mL) were added at –60 °C under N2 to a stirred
solution of the (tert-butyldiphenylsilyl)epoxyethane[10c] (6 mmol) in
THF (12 mL) The mixture was stirred at –60 °C for 20 min, tribu-
tylchlorostannane (10 mmol) was then added, and the system was
stirred at this temperature for 3 h. The mixture was hydrolysed with
methanol (1 mL) and an aq. NH4Cl soln. and extracted with di-
ethyl ether, and the organic layer was dried (MgSO4). The residue
obtained after evaporation of ether was purified by flash
chromatography on silica gel with hexanes/AcOEt 20:1 as eluent to
give 1p (2.5 g, 73%); Rf = 0.44 (hexane/AcOEt, 20:1). 1H NMR
(300 MHz, CDCl3): δ = 0.90 (t, J = 7.3 Hz, 9 H), 0.98–0.86 (m, 6
H), 1.05 (s, 9 H), 1.40–1.12 (m, 12 H), 4.35 (d, J = 6.0 Hz, 1 H),
4.45 (d, J = 6.0 Hz, 1 H), 7.37–7.50 (m, 6 H), 7.67–7.84 (m, 4
H) ppm. C30H48OSiSn (572.25): calcd. C 63.05, H 8.47; found C
62.72, H 8.69.
(121 MHz, CDCl ): δ = 35.07 ppm. IR (CHCl ): ν = 3317, 1437,
˜
3
3
1164 cm–1. C18H23O2P (302.14): calcd. C 71.50, H 7.67; found C
71.21, H 7.32.
(1R,2S)-2-(Diphenylphosphanyl)-1,2-diphenylethanol (2e): Yield
250 mg (63%). Rf = 0.58 (AcOEt); m.p. 170–176 °C (from hexane/
AcOEt). 1H NMR (400 MHz, CDCl3): δ = 3.63 (dd, J = 8.1,
1.8 Hz, 1 H), 5.17 (br. s, 1 H), 5.50 (dd, J = 7.6, 1.8 Hz, 1 H), 6.85–
8.07 (m, 20 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 53.1 (d, J
= 66.2 Hz), 72.4 (d, J = 2.3 Hz), 125.8, 128.1, 129.4, 130.9, 131.7,
132.1, 133.6 (d, J = 95.2 Hz), 141.1 (d, J = 12.2 Hz) ppm. 31P NMR
(162 MHz, CDCl ): δ = 39.89 ppm. IR (CHCl ): ν = 3374, 1437,
General Procedure for the Cleavage of Epoxystannanes with Lithium
Diphenylphosphide: A solution of a stannyloxirane 1a–i or 1k–n
(1 mmol) in THF (5 mL) was added dropwise to a stirred THF
solution of lithium diphenylphosphide (1.5 mmol) [prepared from
diphenylphosphane (0.258 mL, 1.5 mmol) and BuLi (0.936 mL,
1.6  solution in hexane, 1.5 mmol) in THF (5 mL) at 0 °C under
N2 for 30 min]. When starting from distannyloxirane 1j the stan-
nyloxirane/lithium diphenylphosphide molar ratio was 1:2.5. The
mixture was stirred at 0 °C until TLC indicated complete reaction
(reaction time = 1 h–6.5 h). For the silyl-stannyloxiranes 1l and 1o
the mixture was allowed to warm to room temperature and stirred
for 12 h and 30 h, respectively. The reaction mixture was then hy-
drolysed with a saturated aq. NaCO3H solution and extracted with
diethyl ether, and the organic layer was dried (MgSO4). Ether was
evaporated, and the residue was chromatographed to give the com-
pounds characterized below.
˜
3
3
1175 cm–1. C26H22O2P (397.14): calcd. C 78.58, H 5.58; found C
78.18, H 5.22.
Diphenylvinylphosphane Oxide (3a): Yield 22.8 mg (10%); see ref.[9b]
(E)-(2-Phenylethenyl)diphenylphosphane Oxide (3b): Yield 45.6 mg
(15%); see ref.[9b]
(E)-Diphenyl(prop-1-enyl)phosphane Oxide (3c): Yield 29 mg (12%);
see ref.[9b]
(E)-(Hex-1-enyl)diphenylphosphane Oxide (3d): Yield 36.9 mg
(13%); see ref.[9b]
(E)-(Dec-5-enyl)diphenylphosphane Oxide (3e): Yield 251 mg (74%);
see ref.[9b]
(E)-(1,2-Diphenylethenyl)diphenylphosphane Oxide (3f): Yield
41.8 mg (11%); see ref.[9b]
2-(Diphenylphosphanyl)ethanol (2a): Yield 192 mg (78%). Rf = 0.20
(AcOEt). 1H NMR (300 MHz, CDCl3): δ = 2.58 (dt, J = 10.3,
6.3 Hz, 2 H), 3.98 (dt, J = 16.5, 6.3 Hz, 2 H), 4.12 (br. s, 1 H),
7.44–7.53 (m, 6 H), 7.68–7.75 (m, 4 H) ppm. 13C NMR (75 MHz,
CDCl3): δ = 32.4 (d, J = 70.5 Hz), 56.4, 128. 7 (d, J = 11.9 Hz),
130.6 (d, J = 9.6 Hz), 131.9, 132.3 (d, J = 99.5 Hz) ppm. 31P NMR
(E)-Diphenyl[2-(trimethylsilyl)ethenyl]phosphane Oxide (3 g): Yield
129 mg (43%); see ref.[9b]
(E)-Diphenyl[2-(tributylstannyl)ethenyl]phosphane Oxide (3h): Yield
165 mg (32%). Rf = 0.65 (AcOEt); m.p. 155–160 °C (from hexane/
AcOEt). 1H NMR (300 MHz, CDCl3): δ = 0.84–1.02 (m, 15 H),
1.30 (m, 6 H), 1.43–1.64 (m, 6 H) 6.90 (dd, J = 33.2, 20.8 Hz, 1
H), 7.42–7.52 (m, 6 H), 7.63–7.71 (m, 4 H), 7.73 (dd, J = 30.2,
20.8 Hz, 1 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 9.8, 13.6,
27.2 (d, J = 77.4 Hz), 28.9, 128.4 (d, J = 12.0 Hz), 131.4 (d, J =
9.7 Hz), 131.6, 131.7 (d, J = 101.5 Hz), 139.5 (d, J = 85.0 Hz),
(121 MHz, CDCl ): δ = 34.62 ppm. IR (CHCl ): ν = 3364, 1437,
˜
3
3
1172 cm–1. C14H15O2P (246.08): calcd. C 68.29, H 6.14; found C
68.67, H 5.85.
2-(Diphenylphosphanyl)-1-phenylethanol (2b): Yield 229 mg (71%).
1
Rf = 0.40 (AcOEt). H NMR (300 MHz, CDCl3): δ = 2.59 (ddd, J 157.3 (d, J = 8.9 Hz) ppm. 31P NMR (121 MHz, CDCl3): δ = 22.42
= 15.0, 7.1, 2.1 Hz, 1 H), 2.78 (ddd, J = 15.0, 10.9, 10.5 Hz, 1 H),
5.03 (br. s, 1 H), 5.16 (ddd, J = 10.9, 10.5, 2.1 Hz, 1 H), 7.20–7.82
(JP,Sn19 = 177.0, JP,Sn17 = 168.0 Hz) ppm. C26H39OPSn (518.18):
calcd. C 60.37, H 7.60; found C 60.01, H 7.96.
856
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 850–859

Cleavage of Stannyloxiranes with Ph2PLi
(E)-[2-(Dimethylphenylsilyl)ethenyl]diphenylphosphane Oxide (3i):
7.77 (m, 10 H) ppm. IR (film): ν = 1100), 960 cm–1. C H OSiSn
(562.25): calcd. C 63.05, H 8.47; found C 62.61, H 8.82.
˜
30 48
Yield 206 mg (57%); see ref.[9b]
(Z)-[2-(Dimethylphenylsilyl)ethenyl]diphenylphosphane Oxide (3j):
Yield 271 mg (75%). Rf = 0.60 (AcOEt). 1H NMR (300 MHz,
CDCl3): δ = 0.59 (s, 6 H), 7.09 (dd, J = 31.0, 17.4 Hz, 1 H), 7.23
(dd, J = 44.2, 17.4 Hz, 1 H),7.30–7.69 (m, 15 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = –1.20, 127.6, 128.5 (d, J = 11.9 Hz), 128.7,
131.1 (d, J = 9.7 Hz), 131.5, 133.7 (d, J = 97.6 Hz), 133.8, 139.3,
139.6 (d, J = 100.5 Hz), 154.9 (d, J = 6.9 Hz) ppm. 31P NMR
(121 MHz, CDCl3): δ = 21.59 ppm. C22H23OPSi (362.13): calcd. C
72.90, H 6.40; found C 73.38, H 6.77.
(E)-2-(tert-Butyldiphenylsilyloxy)-1-(diphenylphosphanyl)ethene (10b):
Yield 180 mg (39%). Rf = 0.23 (hexanes/AcOEt 5:1). 1H NMR
(300 MHz, CDCl3): δ = 1.20 (s, 9 H), 4.89 (d, J = 24.5 Hz, 1 H),
7.31–7.71 (m, 21 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 18.4,
27.4, 99.0 (d, J = 93.7 Hz), 127.7, 128.3, 128.9, 130.3, 131.3, 132.1,
133.7 (d, J = 103.0 Hz), 135.5, 136.3 ppm. 31P NMR (121 MHz,
CDCl3): δ = 36.64 ppm. C30H31O2PSi (482.18): calcd. C 74.66, H
6.47; found C 74.91, H 6.78.
Acylation of β-Phosphanyl Ketones. – General Procedure: A mixture
of NaH (2 mmol, 48 mg) and β-phosphanyl ketone 4a or 4c
(1 mmol) in THF (8 mL) was stirred at 0 °C under N2 for 30 min.
Acetyl or benzoyl chloride (2 mmol) was then added and the reac-
tion mixture was stirred at room temperature (4a) or 78 °C (4c)
until TLC indicated complete reaction. Quenching with aqueous
1-(Diphenylphosphanyl)propan-2-one (4a): Yield 162 mg (63%). Rf
1
= 0.32 (AcOEt); m.p. 116–118 °C (from hexane/AcOEt). H NMR
(300 MHz, CDCl3): δ = 2.32 (s, 3 H), 3.60 (d, J = 14.8 Hz, 2 H),
7.45–7.58 (m, 6 H), 7.72–7.79 (m, 4 H) ppm. 13C NMR (75 MHz,
CDCl3): δ = 32.6, 47.9 (d, J = 56.5 Hz), 128.7 (d, J = 12.3 Hz),
130.8 (d, J = 9.9 Hz), 131.9 (d, J = 104.2 Hz), 132.3, 201.0 (d, J ammonium chloride, aqueous workup with diethyl ether, drying
= 4.9 Hz) ppm. 31P NMR (121 MHz, CDCl3): δ = 27.02 ppm. IR
(MgSO4) and chromatography gave the products characterized be-
low.
(CHCl ): ν = 1733, 1437, 1195 cm–1. C H O P (258.08): calcd. C
˜
3
15 15
2
69.76, H 5.85; found C 70.10, H 5.55.
3-(Diphenylphosphanyl)pentane-2,4-dione (5a): Yield 276 mg (92%).
Rf = 0.38 (AcOEt). 1H NMR (300 MHz, CDCl3): δ = 2.31 (s, 6 H),
1-(Diphenylphosphanyl)hexan-2-one (4b): Yield 195 mg (65%). Rf =
0.38 (AcOEt); m.p. 120–122 °C (from hexane/AcOEt). 1H NMR 5.98 (d, J = 13.5 Hz, 1 H), 7.47–7.78 (m, 10 H) ppm. 13C NMR
(300 MHz, CDCl3): δ = 0.82 (t, J = 7.3 Hz, 3 H), 1.18 (m, 2 H), (75 MHz, CDCl3): δ = 22.0, 22.2, 109.3 (d, J = 102.5 Hz), 128.4
1.45 (m, 2 H), 2.63 (t, J = 7.3 Hz, 2 H), 3.58 (d, J = 15.0 Hz, 2 H), (d, J = 12.3 Hz), 130.8 (d, J = 9.2 Hz), 131.6, 133.4 (d, J =
7.44–7.57 (m, 6 H), 7.71–7.79 (m, 4 H) ppm. 13C NMR (75 MHz,
CDCl3): δ = 13.6, 21.8, 25.1, 44.9, 46.8 (d, J = 56.7 Hz), 128.6 (d,
107.7 Hz), 163.1 (d, J = 4.6 Hz) ppm. 31P NMR (121 MHz,
CDCl ): δ = 19.15 ppm. IR (film): ν = 1705, 1437, 1170 cm–1.
˜
3
J = 12.4 Hz), 130.7 (d, J = 9.8 Hz), 131.8 (d, J = 103.2 Hz), 132.0, C17H17O3P (300.09): calcd. C 68.00, H 5.71; found C 68.36, H 6.08.
203.0 (d, J = 5.1 Hz) ppm. 31P NMR (121 MHz, CDCl3): δ =
2-(Diphenylphosphanyl)-1-phenylbutane-1,3-dione
(5b):
Yield
27.35 ppm. IR (CHCl ): ν = 1710, 1438, 1198 cm–1. C H O P
˜
3
18 21
2
296 mg (82%) from 4a and 307 mg (85%) from 4c. Rf = 0.40
(300.13): calcd. C 71.98, H 7.05; found C 72.31, H 7.34.
1
(AcOEt). H NMR (300 MHz, CDCl3): δ = 1.96 (s, 3 H), 6.37 (d,
2-(Diphenylphosphanyl)-1-phenylethanone (4c): Yield 224 mg (70%).
Rf = 0.42 (AcOEt); m.p. 140–142 °C (from hexane/AcOEt). 1H
J = 12.9 Hz, 1 H), 7.35–7.84 (m, 15 H) ppm. 31P NMR (121 MHz,
CDCl3): δ = 20.39 ppm. C22H19O3P (362.11): calcd. C 72.92, H
NMR (300 MHz, CDCl3): δ = 4.14 (d, J = 15.4 Hz, 2 H), 7.36– 5.29; found C 72.50, H 4.66.
7.56 (m, 9 H), 7.76–7.83 (m, 4 H), 7.97 (m, 2 H) ppm. 13C NMR
2-(Diphenylphosphanyl)-1,3-diphenylpropane-1,3-dione (5c): Yield
377 mg (89%). Rf = 0.43 (AcOEt). H NMR (300 MHz, CDCl3):
(75 MHz, CDCl3): δ = 43.3 (d, J = 58.0 Hz), 128.5, 128.6 (d, J =
12.9 Hz), 129.2, 131.0 (d, J = 9.9 Hz), 131.8 (d, J = 109.1 Hz),
133.6, 136.9, 192.7 (d, J = 5.0 Hz) ppm. 31P NMR (121 MHz,
1
δ = 6.58 (d, J = 11.0 Hz, 1 H), 7.30–8.10 (m, 20 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 109.6 (d, J = 103.0 Hz), 125.7, 128.5 (d, J
= 16.4 Hz), 128.8, 130.2, 131.0 (d, J = 10.0 Hz), 131.6, 133.0 (d, J =
108.4 Hz), 134.0, 161.4 (d, J = 3.3 Hz) ppm. 31P NMR (121 MHz,
CDCl ): δ = 27.48 ppm. IR (CHCl ): ν = 1675, 1438, 1200 cm–1.
˜
3
3
C20H17O2P (320.10): calcd. C 74.99, H 5.35; found C 75.33, H 5.76.
1-(tert-Butyldiphenylsilyl)-2-(diphenylphosphanyl)ethanone (4d):
CDCl ): δ = 21.05 ppm. IR (film): ν = 1703, 1437, 1178 cm–1.
˜
3
Yield 86.8 mg (18%). Rf = 0.25 (hexanes/AcOEt 5:1). 1H NMR
(300 MHz, CDCl3): δ = 1.06 (s, 9 H), 3.77 (d, J = 12.7 Hz, 2 H),
7.31–7.71 (m, 20 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 17.6,
26.8, 50.5 (d, J = 60.5 Hz), 127.3, 128.2 (d, J = 11.6 Hz), 128.7,
129.8, 130.4 (d, J = 8.3 Hz), 134.3 (d, J = 101.5 Hz), 135.5, 136.3,
δ = 27.91 ppm.
C30H31O2PSi (482.18): calcd. C 74.66, H 6.47; found C 75.01, H
6.78.
C27H21O3P (424.43): calcd. C 76.41, H 4.99; found C 76.26, H 4.64.
Treatment of β-Phosphanyl Ketones with Hydroxylamine. – General
Procedure: A mixture of a β-phosphanyl ketone 4a–c (1 mmol), hy-
droxylamine hydrochloride (4 mmol) and sodium acetate (4 mmol)
was heated at reflux in a water/ethanol mixture (15:1, 16 mL) for
6 h. The reaction mixture was extracted with CH2Cl2, the organic
layer was dried (MgSO4), and the solvent was evaporated under
reduced pressure. The following oximes 6a–c were isolated:
238.7 ppm. 31P NMR (121 MHz, CDCl3):
1,2-Bis(diphenylphosphanyl)ethanol (9): Yield 227 mg (51%). Rf =
0.20 (AcOEt). 1H NMR (300 MHz, CDCl3): δ = 2.47 (m, 1 H),
2.96 (m, 1 H), 4.96 (m, 1 H), 7.19–7.81 (m, 20 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 29.7 (d, J = 69.0 Hz), 66.6 (d, J = 85.6 Hz),
127.6, 128.5, 129.1, 130.6, 131.3, 132.1, 133.6, 133.8 ppm. 31P
NMR (121 MHz, CDCl3): δ = 37.09 (d, JP,P = 50.9 Hz), 30.78 (d,
(Z,E)-[2-(Hydroximino)propyl]diphenylphosphane Oxide (6a): Yield
202 mg (74%). Rf = 0.26 (AcOEt); m.p. 188–190 °C (from hexane/
CH2Cl2). Z Isomer: 101 mg (37%). H NMR (300 MHz, CDCl3):
1
δ = 1.94 (d, J = 2.0 Hz, 3 H), 3.29 (d, J = 13.8 Hz, 2 H), 7.35–7.54
(m, 6 H), 7.72–7.75 (m, 4 H), 10.34 (br. s, 1 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 20.9, 37.4 (d, J = 67.5 Hz), 128.2 (d, J =
11.5 Hz), 130.4 (d, J = 9.6 Hz), 131.5, 132.7 (d, J = 100.2 Hz),
148.9 ppm. 31P NMR (121 MHz, CDCl3): δ = 29.63. E Isomer:
JP,P = 50.9 Hz) ppm. IR (CHCl ): ν = 3368, 1438, 1175 cm–1.
˜
3
C26H24O3P2 (446.12): calcd. C 69.95, H 5.42; found C 70.36, H
5.13.
1
101 mg (37%) ppm. H NMR (300 MHz, CDCl3): δ = 1.98 (d, J =
(E)-1-(tert-Butyldiphenylsilyloxy)-2-(tributylstannyl)ethene
(10a):
2.1 Hz, 3 H), 3.60 (d, J = 14.9 Hz, 2 H), 7.35–7.54 (m, 6 H), 7.72–
7.75 (m, 4 H), 10.67 (br. s, 1 H) ppm. 13C NMR (75 MHz, CDCl3):
δ = 14.9, 30.7 (d, J = 66.1 Hz), 128.0 (d, J = 10.2 Hz), 130.4 (d,
J = 9.6 Hz), 131.5, 132.4 (d, J = 99.4 Hz), 148.8 ppm. 31P NMR
Yield 268 mg (47%). Rf = 0.60 (hexanes). 1H NMR (300 MHz,
CDCl3): δ = 0.74–0.96 (m, 15 H), 1.10 (s, 9 H), 1.20–1.75 (m, 12
H), 5.04 (d, J = 14.8 Hz, 1 H), 6.24 (d, J = 14.8 Hz, 1 H), 7.33–
Eur. J. Org. Chem. 2009, 850–859
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
857

A. M. González-Nogal, P. Cuadrado, M. A. Sarmentero
FULL PAPER
(121 MHz, CDCl3): δ = 29.54 ppm. C15H16NO2P (273.09): calcd.
21.7, 21.8, 25.2, 44.9, 46.7 (d, J = 57.1 Hz), 128.2 (d, J = 11.4 Hz),
C 65.93, H 5.90, N 5.13; found C 66.20, H 5.65, N 4.81.
130.8, 131.8 (d,
6.7 Hz) ppm. 31P NMR (121 MHz, CDCl3): δ = 27.98 ppm. IR
(film): ν = 3053, 1591, 1437, 1265, 1193 cm–1. C H NO PS
(469.15): calcd. C 63.95, H 6.01, N 2.98; found C 64.21, H 5.86, N
2.74.
J = 8.8 Hz), 133.3, 144.4, 161.9 (d, J =
(Z,E)-[2-(Hydroximino)hexyl]diphenylphosphane Oxide (6b): Yield
195 mg (62%). Rf = 0.32 (AcOEt). Z isomer: 65 mg (41%). 1H
NMR (300 MHz, CDCl3): δ = 0.85 (t, J = 7.3 Hz, 3 H), 1.20 (m,
2 H), 1.37 (m, 2 H), 2. 38 (t, J = 7.6 Hz, 2 H), 3.29 (d, J = 14.2 Hz,
2 H), 7.33–7.45 (m, 6 H), 7.63–7.82 (m, 4 H), 10.29 (br. s, 1 H) ppm.
13C NMR (75 MHz, CDCl3): δ = 13.5, 22.7, 27.3, 34.4, 36.0 (d, J
= 67.7 Hz), 128.8 (d, J = 12.1 Hz), 130.1 (d, J = 8.9 Hz), 131.5,
132.8 (d, J = 100.4 Hz), 153.7 ppm. 31P NMR (121 MHz, CDCl3):
δ = 29.76. E isomer: 130 mg (41%) ppm. 1H NMR (300 MHz,
CDCl3): δ = 0.76 (t, J = 7.3 Hz, 3 H), 1.22 (m, 2 H), 1.40 (m, 2
H), 2. 28 (t, J = 6.8 Hz, 2 H), 3.60 (d, J = 15.4 Hz, 2 H), 7.33–7.45
(m, 6 H), 7.63–7.82 (m, 4 H), 10.59 (br. s, 1 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 13.8, 22.0, 28.1, 29.9 (d, J = 66.0 Hz), 34.4,
128.3 (d, J = 12.2 Hz), 130.8 (d, J = 9.8 Hz), 131.8 (d, J = 2.1 Hz),
132.4 (d, J = 101.2 Hz), 151.8 (d, J = 7.5 Hz) ppm. 31P NMR
(121 MHz, CDCl3): δ = 29.58 ppm. C18H22NO2P (315.14): calcd.
C 68.56, H 7.03, N 4.44; found C 68.81, H 7.36, N 4.71.
˜
25 28
4
(E)-2-Phenyl-[2-(p-tolylsulfonyloximino)ethyl]diphenylphosphane
Oxide (7c): Yield 205 mg (42%). Rf = 0.45 (AcOEt); m.p. 142–
144 °C (from pyridine/water). 1H NMR (300 MHz, CDCl3): δ =
2.44 (s, 3 H), 4.01 (d, J = 15.4 Hz, 2 H), 7.23 (m, 3 H), 7.45 (m, 6
H), 7.52–7.83 (m, 5 H) ppm. 31P NMR (121 MHz, CDCl3): δ =
26.18 ppm. C27H24NO4PS (489.12): calcd. C 66.25, H 4.94, N 2.86;
found C 65.91, H 5.14, N 4.68.
Synthesis of 2-(Diphenylphosphanyl)-3-methyl-2H-azirine (8): Tri-
ethylamine (2 mmol, 0.258 mL) was added to a solution of the N-
tosyloxime 7a (1 mmol) in dry THF (5 mL) at 0 °C. After stirring
for 10 h at this temperature, the mixture was diluted with CH2Cl2
and washed with a solution of HCl (2 ) and with water. The or-
ganic layer was dried (MgSO4), and solvents were evaporated under
reduced pressure. The crude product was purified by crystallisation
from hexane/CH2Cl2 to give 8 (234 mg, 92%) as a white solid; m.p.
(E)-[2-(Hydroximino)-2-(phenyl)ethyl]diphenylphosphane Oxide (6c):
Yield 187 mg (56%). Rf = 0.41 (AcOEt); m.p. 183–185 °C (from
hexane/AcOEt). 1H NMR (300 MHz, CDCl3): δ = 4.05 (d, J =
15.5 Hz, 2 H), 7.20 (m, 3 H), 7.50 (m, 6 H), 7.60 (m, 2 H), 7.80
(m, 4 H), 11.51 (br. s, 1 H) ppm. 13C NMR (75 MHz, CDCl3): δ =
28.9 (d, J = 64.4 Hz), 126.4, 128.8 (d, J = 11.7 Hz) 130.3, 130.9 (d,
J = 9.3 Hz), 131.6, 132.8, 134.0 (d, J = 98.8 Hz), 135.8, 149.0 (d,
J = 9.2 Hz) ppm. 31P NMR (121 MHz, CDCl3): δ = 28.54 ppm.
C20H18NO2P (335.11): calcd. C 71.63, H 5.41, N 4.18; found C
71.31, H 5.73, N 4.42.
1
98–99 °C. H NMR (300 MHz, CDCl3): δ = 2.24 (d, J = 36.6 Hz,
1 H), 2.43 (s, 3 H), 7.51 (m, 6 H), 7.73 (m, 4 H) ppm. 31P NMR
(121 MHz, CDCl3): δ = 30.56 ppm. C15H14NOP (255.08): calcd. C
70.58, H 5.53, N 5.49; found C 70.82, H 5.40, N 5.75.
Acknowledgments
We thank the Spanish Ministerio de Ciencia y Tecnología (MCYT)
for supporting this work.
Preparation of N-Tosyloximes. Typical Procedure: Tosyl chloride
(1.03 mmol) was added at 0 °C to a stirred solution of an oxime
6a–c (1 mmol) in dry pyridine (1 mL), and stirring was continued
for 1 h. The mixture was allowed to warm to room temperature
and stirred for 1 h. Quenching with ice water (13 mL) afforded a
white precipitate, which was isolated by filtration in vacuo and
washed with water several times. The following products were ob-
tained.
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(Z,E)-[2-(p-Tolylsulfonyloximino)propyl]diphenylphosphane Oxide
(7a): Yield 298 mg (70%). Rf = 0.35 (AcOEt); m.p. 130–133 °C
(from pyridine/water).
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isomer: 43 mg (10%). 1H NMR
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(300 MHz, CDCl3): δ = 2.15 (d, J = 1.8 Hz, 3 H), 2.43 (s, 3 H),
3.58 (d, J = 14.7 Hz, 2 H), 7.20–7.81 (m, 14 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 17.2, 21.9, 34.4 (d, J = 64.5 Hz), 128.2,
130.4, 131.5, 132.5, 144.9, 159.8 ppm. 31P NMR (121 MHz,
CDCl3): δ = 27.05. E isomer: 255 mg (60%) ppm. 1H NMR
(300 MHz, CDCl3): δ = 2.11 (d, J = 1.8 Hz, 3 H), 2.47 (s, 3 H),
3.32 (d, J = 13.9 Hz, 2 H), 7.20–7.81 (m, 14 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 17.3, 21.7, 38.0 (d, J = 63.3 Hz), 128.2,
130.4, 131.5, 132.5, 144.8, 161.9 ppm. 31P NMR (121 MHz,
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˜
3
1192 cm–1. C22H22NO4PS (427.10): calcd. C 61.82, H 5.19, N 3.28;
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(Z,E)-[2-(p-Tolylsulfonyloximino)hexyl]diphenylphosphane
Oxide
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(14%). 1H NMR (300 MHz, CDCl3): δ = 0.84 (t, J = 7.3 Hz, 3 H),
1.14 (m, 2 H), 1.42 (m, 2 H), 1.99 (s, 3 H), 2. 36 (t, J = 7.3 Hz, 2
H), 3.61 (d, J = 15.3 Hz, 2 H), 7.33–7.45 (m, 8 H), 7.63–7.83 (m,
6 H) ppm. 31P NMR (121 MHz, CDCl3): δ = 27.70 ppm. E isomer:
1
189 mg (40%) ppm. H NMR (300 MHz, CDCl3): δ = 0.78 (t, J =
7.2 Hz, 3 H), 1.14 (m, 2 H), 1.42 (m, 2 H), 2.00 (s, 3 H), 2. 58 (t,
J = 7.3 Hz, 2 H), 3.58 (d, J = 15.1 Hz, 2 H), 7.33–7.45 (m, 8 H),
7.63–7.83 (m, 6 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 13.7,
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The H and 13C NMR spectra of the compound 2e are iden-
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Received: October 10, 2008
Published Online: January 8, 2009
Eur. J. Org. Chem. 2009, 850–859
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
859