Regio- and stereospecific cleavage of silyl- and disilylepoxides with lithium diphenylphosphide

Article abstract of DOI:10.1002/chem.200400239

Unsubstituted or α- and β-C-substituted silylepoxides react stereospecifically with lithium diphenylphosphide, optionally followed by methylation, to give vinylphosphonium iodides or vinylphosphine oxides resulting from α-opening and silyl enol ethers, vi

Full text of DOI:10.1002/chem.200400239

FULL PAPER
Regio- and Stereospecific Cleavage of Silyl- and Disilylepoxides with Lithium
Diphenylphosphide
Purificación Cuadrado, Ana M. Gonzµlez-Nogal,* and M. Angeles Sarmentero[a]
Abstract: Unsubstituted or a- and b-C-substituted silylepoxides react stereospecifi-
cally with lithium diphenylphosphide, optionally followed by methylation, to give
vinylphosphonium iodides or vinylphosphine oxides resulting from a-opening and
silyl enol ethers, vinylsilanes or a-hydroxysilanes by b-opening. On the other hand,
a,b- or a,a-disilylepoxides afforded b-silyl vinylphosphine oxides or a-silylated
silyl enol ethers by a- and b-cleavage, respectively. All compounds are interesting
synthons in organic chemistry.
Keywords: cleavage reactions
enols epoxysilanes
phosphaalkenes · silyl enol ethers
·
·
·
Introduction
philic attack of lithium diphenylphosphide giving stereospe-
cifically vinylphosphines resulting from Peterson elimina-
tion,[6,7] which were spontaneously oxidised to the corre-
sponding oxides in the final hydrolysis or converted to vinyl-
phosphonium iodides by subsequent treatment with methyl
iodide (Schemes 1 and 2).
In a preliminary communication[1] we reported the regio-
and stereospecific synthesis of vinylphosphonium iodides by
a-cleavage of unsubstituted or trans-b-alkyl substituted di-
methylphenylsilyl- or tert-butyldiphenylsilylepoxides with
lithium diphenylphosphide followed by reaction with methyl
iodide. Under the same conditions, the trans-b-phenyl-a-tert-
butyldiphenylsilylepoxide led to the corresponding (Z)-silyl
enol ether resulting from b-opening.
With the aim of exploring the scope of this procedure, we
have extended this methodology to silylepoxides with vari-
ous substitution patterns, such as a-C and cis-b-C substitu-
tion, a- or b-silyl substitution by different silyl groups and
tri-substitution. These substrates have been synthesised by
epoxidation of vinylsilanes obtained previously by dimethyl-
phenyl- and tert-butyldiphenylsilyl cupration starting from
alkynes[2,3] or allenes.[4,5]
Scheme 1.
In this paper, we describe the results obtained in the
cleavage of silylepoxides 1 and disilylepoxides 2 by lithium
diphenylphosphide, optionally followed by methylation.
Under the latter conditions, the initially formed unsubsti-
tuted vinylphosphonium iodide—resulting from the a-cleav-
age of 1a and 1b—was transformed to the 1-methylvinyl-
phosphonium iodide 4a and to the iodoalkylidenephosphor-
ane 5, respectively. Compound 5 appears to be formed by
1,4-addition of an iodide ion and 4a through a-methylation
of 5 followed by E2 elimination of HI by the action of the
dimethylphenylsiloxide ion (Scheme 3).
Results and Discussion
Unsubstituted or cis- and trans-b-alkyldimethylphenylsilyl-
and tert-butyldiphenylsilylepoxides 1a–h undergo a-nucleo-
b-Phenylsilylepoxides experience a- or b-opening depend-
ing on the nature of the silyl group[8] and the configuration.
The cis-b-phenyl-a-tert-butyldiphenylsilylepoxide (1i) and
the trans-b-phenyl-a-dimethylphenylsilylepoxide (1j) were
opened by nucleophilic a-attack giving the corresponding vi-
nylphosphine oxides 3 f and 3g or the vinylphosphonium
[a] Dr. P. Cuadrado, Prof. A. M. Gonzµlez-Nogal, M. A. Sarmentero
Departamento de Química Orgµnica
Universidad de Valladolid
47011 Valladolid (Spain)
E-mail: agn@qo.uva.es
Chem. Eur. J. 2004, 10, 4491 – 4497
DOI: 10.1002/chem.200400239
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4491

FULL PAPER
Scheme 4.
Scheme 2.
phenyl group with the incipient carbocation resulting from
b-opening (Scheme 5).
Scheme 5.
The gem-methyl substituted silylepoxides 1l and 1m un-
dergo b-opening to give b-diphenylphosphino-a-oxidosilane
intermediate 9a and 9b, which evolve in a different way;
this depends on the nature of the silyl group (Schemes 6 and
7).
Scheme 3.
iodide 4c. On the other hand, the trans-b-phenyl-a-tert-bu-
tyldiphenylsilylepoxide (1k) underwent nucleophilic attack
at b-carbon followed by Brook rearrangement[9] with simul-
taneous elimination of a good leaving group (methyldiphe-
nylphosphine) to give the (Z)-silyl enol ether 6a. Even
when the methylation was omitted, the elimination of diphe-
nylphosphide also took place, but the yield of the silyl enol
ether 6a was slightly lower (Scheme 4).
Probably, this behaviour is due to a combination of elec-
tronic (benzylic b-carbon) and steric effects. The hindered
tert-butyldiphenylsilyl group favours the b-opening, especial-
ly when the b-carbocation to the silicon can also be stabi-
lised by the phenyl group. Perhaps, this is only possible in
the trans-b-phenyl-a-tert-butyldiphenylsilylepoxide (1k) be-
cause in the cis-isomer 1i the bulky tert-butyldiphenylsilyl
group prevents the co-planarity and conjugation of the b-
Scheme 6.
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Chem. Eur. J. 2004, 10, 4491 – 4497

Cleavage of Silyl- and Disilylepoxides
4491 – 4497
nature, relative position and configuration of both silyl
groups.
The trans-a,b-disilylepoxides 2a–c are opened by nucleo-
philic a-attack to the less hindered silyl group followed by
Peterson elimination to give the corresponding vinylphos-
phine oxides. When both silyl groups do not have a very dif-
ferent size, such as 2b (trimethyl and dimethylphenyl), a 2:1
mixture of two possible vinylphosphine oxides 3k and 3l
was obtained. However, if they are of drastically different
size as in 2c (trimethyl and tert-butyldiphenyl) the diphenyl-
phosphide attacks only at the carbon bearing the trimethyl-
silyl group. In this case, the reactivity decreases, long reac-
tion times are required (96 h) and the yield of 3m is lower.
The trisubstituted a,b-disilylepoxides 2d–f afforded only the
vinylphosphine oxide, which resulted from a-attack to the
monosubstituted carbon. When this position bears the tert-
butyldiphenylsilyl group the reaction did not take place. The
epoxide 2g was recovered even if a large excess of lithium
diphenylphosphide (3.5 equiv) and long reaction times
(120 h) were used (Scheme 9).
Scheme 7.
The dimethylphenylsilyl intermediate 9a was hydrolysed
to the corresponding a-hydroxysilane 7; on the other hand,
when methylated, the vinylsilane 8a, which resulted from
Wittig elimination of the intermediate 10a, was obtained.
Nevertheless, the tert-butyldiphenylsilyl intermediate 9b, or
the methylated intermediate 10b, experience a Brook rear-
rangement with elimination of the phosphorous leaving
group to give the silyl enol ether 6b. If the methylation is
omitted, the result is the same but the yield of 6b is lower.
The different behaviour of the intermediates 10a and 10b
may depend on two factors: a) higher migratory aptitude of
the tert-butyldiphenylsilyl than the dimethylphenylsilyl
group (phenyl groups on silicon have been shown to acceler-
ate the Brook rearrangement[10,11]) and b) the stability of the
necessary conformation for the syn-elimination of diphenyl-
methylphosphine oxide. Probably, the intermediate 10b
does not undergo Wittig elimination due to the fact that in
this conformation the bulky tert-butyldiphenylsilyl group
should be eclipsed, whereas in the conformation for Brook
rearrangement and anti-elimination this group is staggered
(Scheme 7).
The silylepoxides a,b- or b,b-disubstituted 1n–q react
with lithium diphenylphosphide to give exclusively the cor-
responding diphenylphosphine oxides 3h–j, which resulted
from a-opening (Scheme 8).
Scheme 9.
On the other hand, the behaviour of the disilylepoxides 2
toward the lithium diphenylphosphide depend on the
The cis-a,b-disilylepoxide 2h was also opened by a-attack
to the less hindered silyl group, but the intermediate now
experienced Wittig elimination to afford the 1,2-disilylethy-
lene 8b.
The intermediates 9c and 9d, which resulted from the a-
opening at the trimethylsilyl group of the trans- and cis-a-
trimethyl-b-tert-butyldiphenylsilylepoxides 2c and 2h, may
evolve by a different path depending on the steric require-
ments for the Wittig or Peterson eliminations. In case of the
intermediate 9c, the conformation required for a Peterson
elimination is more stable than that necessary for Wittig
elimination (the silyl and phosphino groups are eclipsed).
Likewise, the differential stability of the corresponding con-
formations in the intermediate 9d is the opposite
(Scheme 10).
Scheme 8.
Chem. Eur. J. 2004, 10, 4491 – 4497
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A. Gonzµlez-Nogal et al.
FULL PAPER
a-silylated silyl enol ethers, obtained by a- or b-cleavage of
1,2- or 1,1-disilylated epoxides, are even more versatile syn-
thons.
Experimental Section
General: THF was distilled from sodium/benzophenone in a recycling
still. All chromatographic and work-up solvents were distilled prior to
use. All reactions involving organometallic 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, Macherey-Nagel). Flash chromatography was performed on silica gel
60 (230–400 mesh, M-N). Silylepoxides 1a–q were prepared by epoxida-
tion[15,3] of the corresponding vinylsilanes obtained by reaction with elec-
trophiles of the intermediates from dimethylphenylsilyl- or tert-butyldi-
phenylsilylcupration of alkynes[2,3] (1a–k and 1n–q) or allene[4,5] (1l and
1m).
Scheme 10.
The b-unsubstituted gem-disilylepoxides 2i and 2j under-
go b-opening to give the a-silylated silyl enol ethers 6c and
6d resulting from Brook rearrangement of the tert-butyldi-
phenylsilyl group, together with minor amounts of the gem-
disilylalkenes 8c and 8d formed by Wittig elimination. On
the contrary, the b-methyl gem-disilylepoxide 2k afforded
exclusively the gem-disilylalkene 8e, which resulted from a
Wittig elimination. If the methylation is omitted the results
are the same, but the yields were lower (Scheme 11).
Synthesis
of
1,2-disilylepoxides—Typical
procedure:
MCPBA
(1.35 mmol) and NaHCO3 (2 mmol) were added to a solution of 1,2-disi-
lylalkene[3,16] (1 mmol) in CH2Cl2 (3 mL) (trimethylsilyl- and dimethyl-
phenylsilylalkenes) or in CHCl3 (3 mL) (tert-butyldiphenylsilylalkenes).
The reaction mixture was stirred at room temperature in CH2Cl2 or
under reflux in CHCl3, respectively, until TLC indicated complete reac-
tion. The mixture was washed several times with an aqueous solution of
NaHSO3, NaHCO3, and NaCl. The organic layer was dried (MgSO4), the
solvent removed and the residue was purified by chromatography (silica
gel, hexanes/AcOEt) to give the following products,
(E)-1,2-Bis(dimethylphenylsilyl)epoxyethane (2a): Yield=90%; Rf =0.46
(hexanes/AcOEt 20:1); 1H NMR (300 MHz, CDCl3): d=0.36 (s, 12H),
2.30 (s, 2H), 7.40–7.56 (m, 10H); IR (film): n˜ =1230, 1100 cmÀ1; elemen-
tal analysis calcd (%) for C18H24OSi2 (312.14): C 69.17, H 7.74; found: C
69.29, H 7.65.
(E)-1-Dimethylphenylsilyl-2-trimethylsilylepoxyethane (2b): Yield=
85%; Rf =0.50 (hexanes/AcOEt 20:1); 1H NMR (300 MHz, CDCl3): d=
0.12 (s, 9H), 0.35 (s, 3H), 0.41 (s, 3H), 2.18 (d, J=5.0 Hz, 1H), 2.31 (d,
J=5.0 Hz, 1H), 7.40–7.45 (m, 3H), 7.60–7.63 (m, 2H); 13C NMR
(75 MHz, CDCl3): d=À5.5, À5.3, À3.8, 46.6, 47.4, 127.8, 129.4, 133.8,
136.4; IR (film): n˜ =1250, 1120 cmÀ1; elemental analysis calcd (%) for
C13H22OSi2 (250.12): C 62.34, H 8.85; found: C 62.51, H 8.91.
Scheme 11.
(E)-1-tert-Butyldiphenylsilyl-2-trimethylsilylepoxyethane (2c): Yield=
75%; Rf =0.46 (hexanes/AcOEt 20:1); 1H NMR (300 MHz, CDCl3): d=
0.83 (s, 9H), 1.23 (s, 9H), 1.99 (d, J=4.9 Hz, 1H), 2.65 (d, J=4.9 Hz,
1H), 7.30–7.38 (m, 10H); 13C NMR (75 MHz, CDCl3): d=À3.6, 18.7,
Conclusion
In conclusion, the a- or b-opening of silylepoxides by lithi-
um diphenylphosphide depends on electronic and steric fac-
tors. In general, the a-attack is preferred, except when the
a-position is hindered. We have stereospecifically synthes-
ised vinylphosphonium salts or vinylphosphonium oxides
with retention of configuration by a-attack of diphenylphos-
phide ion to epoxysilanes, followed by Peterson elimination.
These compounds are suitable reagents for the synthesis of
a variety of heterocyclic, carbocyclic and chain-extended
systems.[12] On the other hand, when the a-position is hin-
dered (gem-disubstituted epoxysilanes or epoxides bearing
the bulky tert-butyldiphenylsilyl group) the nucleophilic
attack occurs exclusively at the b-carbon to afford vinylsi-
lanes, which result from a Wittig elimination, or silyl enol
ethers, which are formed by a Brook rearrangement and
anti-elimination. The silyl enol ether is one of the more
useful functional groups in organic synthesis[13] and few
methods exist which provide them in a stereocontrolled
manner.[14] Moreover, b-silyl vinylphosphine oxides and
27.9, 44.3, 46.9, 127.4, 129.0, 134.8, 137.0; IR (film): n˜ =1240, 1100 cmÀ1
;
elemental analysis calcd (%) for C21H30OSi2 (354.18): C 71.12, H 8.53;
found: C 70.92, H 8.42.
(E)-1,2-Bis(dimethylphenylsilyl)-1,2-epoxypropane (2d): Yield=85%;
1
Rf =0.46 (hexanes/AcOEt 20:1); H NMR (300 MHz, CDCl3): d=0.33 (s,
3H), 0.39 (s, 3H), 0.45 (s, 3H), 0.47 (s, 3H), 1.23 (s, 3H), 2.39 (s, 1H),
7.37–7.45 (m, 6H), 7.56–7.59 (m, 4H); 13C NMR (75 MHz, CDCl3): d=
À5.7, À2.8, À2.1, 18.8, 52.7, 53.9, 127.8, 127.9, 129.2, 129.3, 134.0, 133.9,
136.3, 137.5; IR (film): n˜ =1250, 1110 cmÀ1; elemental analysis calcd (%)
for C19H26OSi2 (326.15): C 69.88, H 8.02; found: C 70.01, H 7.86.
(E)-1-Dimethylphenylsilyl-2-trimethylsilyl-1,2-epoxypropane
(2e):
Yield=80%; Rf =0.54 (hexanes/AcOEt 20:1)
;
1H NMR (300 MHz,
CDCl3): d=0.07 (s, 9H), 0.44 (s, 3H), 0.46 (s, 3H), 1.23 (s, 3H), 2.31 (s,
1H), 7.39–7.41 (m, 3H), 7.58–7.61 (m, 2H); 13C NMR (75 MHz, CDCl3):
d=À4.1, À2.8, À2.2, 18.6, 52.8, 54.3, 127.9, 129.2, 133.7, 137.7; IR (film):
n˜ =1250, 1110 cmÀ1
; elemental analysis calcd (%) for C14H24OSi2
(264.14): C 63.57, H 9.15; found: C 63.62, H 8.97.
(E)-1,2-Bis(dimethylphenylsilyl)-1-phenylepoxyethane (2 f): Yield=78%;
Rf =0.44 (hexanes/AcOEt 20:1); 1H NMR (300 MHz, CDCl3): d=À0.06
(s, 3H), À0.02 (s, 3H), 0.35 (s, 3H), 0.37 (s, 3H), 2.74 (s, 1H), 7.03–7.54
(m, 15H); 13C NMR (75 MHz, CDCl3): d=À5.5, À5.3, À4.9, À3.3, 54.3,
59.6, 126.2, 127.0, 127.4, 127.6, 127.7, 129.1, 129.4, 133.7, 134.3, 135.8,
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Cleavage of Silyl- and Disilylepoxides
4491 – 4497
137.4, 140.1; IR (film): n˜ =1250, 1100 cmÀ1; elemental analysis calcd (%)
for C24H28OSi2 (388.17): C 74.17, H 7.26; found: C 74.22, H 7.30.
(121 MHz, CDCl3): d=24.65; IR (film): n˜ =1180, 985, 900 cmÀ1; elemen-
tal analysis calcd (%) for C14H13OP (228.07): C 73.68, H 5.74; found: C
73.57, H 5.82.
(E)-1-tert-Butyldiphenylsilyl-2-trimethylsilyl-1,2-epoxypropane
(2g):
Yield=70%; Rf =0.54 (hexanes/AcOEt 20:1); 1H NMR (300 MHz,
CDCl3): d=0.11 (s, 9H), 0.89 (s, 3H), 1.14 (s, 9H), 2.74 (s, 1H), 7.33–7.44
(m, 6H), 7.68–7.72 (m, 4H); 13C NMR (75 MHz, CDCl3): d=À4.0, 17.7,
18.8, 27.7, 50.0, 54.3, 127.7, 129.4, 133.7, 136.1; IR (film): n˜ =1250,
1110 cmÀ1; elemental analysis calcd (%) for C22H32OSi2 (368.20): C 71.67,
H 8.75; found: C 71.59, H 8.83.
(Z)-1-Propenyldiphenylphosphine oxide (3b): Yield=76% from 1c and
60% from 1d; Rf =0.41 (AcOEt); 1H NMR (300 MHz, CDCl3): d=2.06
(ddd, J=1.4, 2.9, 7.2 Hz, 3H), 6.09 (ddq, J=1.4, 12.8, 25.6 Hz, 1H), 6.75
(ddq, J=7.2, 12.8, 40.3 Hz, 1H), 7.40–7.56 (m, 6H), 7.64–7.74 (m, 4H);
13C NMR (75 MHz, CDCl3): d=17.1 (d, J=8.9 Hz), 122.1 (d, J=
100.8 Hz), 128.4 (d, J=12.0 Hz), 130.7 (d, J=10.0 Hz), 131.4, 134.2 (d,
J=103.8 Hz), 149.6; 31P NMR (121 MHz, CDCl3): d=22.32; IR (film):
n˜ =1175 cmÀ1; elemental analysis calcd (%) for C15H15OP (242.09): C
74.37, H 6.24; found: C 74.51, H 6.09.
(Z)-1-tert-Butyldiphenylsilyl-2-trimethylsilylepoxyethane (2h): Yield=
60%; Rf =0.54 (hexanes/AcOEt 20:1); 1H NMR (300 MHz, CDCl3): d=
À0.36 (s, 9H), 1.10 (s, 9H), 2.65 (d, J=6.5 Hz, 1H), 3.15 (d, J=6.5 Hz,
1H), 7.30–7.46 (m, 6H), 7.60–7.73 (m, 4H); IR (film): n˜ bar=1250,
1110 cmÀ1; elemental analysis calcd (%) for C21H30OSi2 (354.18): C 71.12,
H 8.53; found: C 71.29, H 8.41.
(Z)-1-Hexenyldiphenylphosphine oxide (3c): Yield=58%; Rf =0.46
(AcOEt); 1H NMR (300 MHz, CDCl3): d=0.78 (t, J=7.2 Hz, 3H), 1.22
(m, 2H), 1.31 (m, 2H), 2.50 (ddt, J=1.5, 6.1, 7.2 Hz, 2H), 6.09 (tdd, J=
1.5, 12.9, 25.7 Hz, 1H), 6.66 (tdd, J=7.7, 12.9, 40.5 Hz, 1H), 7.30–7.76
(m, 10H); 13C NMR (75 MHz, CDCl3): d=13.7, 22.1, 30.6, 30.8, 121.1 (d,
J=100.1 Hz), 128.4 (d, J=12.0 Hz), 130.8 (d, J=9.81 Hz), 131.4, 134.3 (d,
J=103.9 Hz), 155.1; 31P NMR (121 MHz, CDCl3): d=21.87; IR (film):
n˜ =1177, 700 cmÀ1; elemental analysis calcd (%) for C18H21OP (284.13): C
76.04, H 7.44; found: C 76.41, H 7.39.
Synthesis of 1,1-disilylepoxides—Typical procedure: BuLi (1.2 mmol,
1.6m in hexane, 0.75 mL) and TMEDA (1.2 mmol) were added at À608C
to a solution of the silylepoxides 1b or 1d (1 mmol) in THF (2 mL). The
mixture was stirred under N2 at À608C for 20 min and then chlorotrime-
thylsilane or chlorodimethylphenylsilane (1.65 mmol) was added and stir-
red at this temperature for 3 h. The mixture was hydrolysed with metha-
nol (1 mL) and an aq. NH4Cl solution, extracted with diethyl ether and
the organic layer dried (MgSO4). Chromatography of the residue ob-
tained after evaporation of ether gave the following products.
(E)-1-Hexenyldiphenylphosphine oxide (3d): Yield=83% from 1 f and
62% from 1h; Rf =0.46 (AcOEt); 1H NMR (300 MHz, CDCl3): d=0.88
(t, J=7.3 Hz, 3H), 1.32 (m, 2H), 1.45 (m, 2H), 2.28 (tdd, J=1.5, 6.5,
7.5 Hz, 2H), 6.21 (ddt, J=1.5, 17.0, 24.7 Hz, 1H), 6.72 (ddt, J=6.5, 17.0,
19.6 Hz, 1H), 7.40–7.52 (m, 6H), 7.64–7.71 (m, 4H); 13C NMR (75 MHz,
CDCl3): d=13.7, 22.1, 29.9, 34.1 (d, J=16.9 Hz), 121.3 (d, J=103.5 Hz),
128.4 (d, J=12.1 Hz), 131.2 (d, J=9.9 Hz), 131.6, 133.0 (d, J=104.8 Hz),
152.9; 31P NMR (121 MHz, CDCl3): d=24.50; IR (film): n˜ =1180,
920 cmÀ1; MS (EI, 70 eV): m/z (%): 284 (43) [M +], 255 (27), 227 (16),
202 (100), 185 (8), 77 (44); elemental analysis calcd (%) for C18H21OP
(284.13): C 76.04, H 7.44; found: C 76.18, H 7.51.
1-tert-Butyldiphenylsilyl-1-trimethylsilylepoxyethane (2i): Yield=85%;
Rf =0.49 (hexanes/AcOEt 20:1); 1H NMR (300 MHz, CDCl3): d=À0.16
(s, 9H), 1.17 (s, 9H), 3.03 (d, J=5.7 Hz, 1H), 3.22 (d, J=5.7 Hz, 1H),
7.36–7.46 (m, 6H), 7.66–7.84 (m, 4H); 13C NMR (75 MHz, CDCl3): d=
À1.8, 19.3, 28.6, 44.7, 49.9, 127.6, 129.4, 133.9, 136.2; IR (film): n˜ =1250,
1110 cmÀ1; MS (EI, 70 eV): m/z (%): 354 (1) [M +ÀtBu], 297 (2), 271
(12), 255 (5), 219 (14), 193 (39), 73 (100), 57 (79); elemental analysis
calcd (%) for C21H30OSi2 (354.18): C 71.12, H 8.53; found: C 70.86, H
8.42.
(E)-1-Propenyldiphenylphosphine oxide (3e): Yield=59%; Rf =0.41
(AcOEt); 1H NMR (300 MHz, CDCl3): d=1.98 (td, J=1.6, 6.5 Hz, 3H),
6.26 (ddq, J=16.9, 24.1, 1.6 Hz, 1H), 6.69 (ddq, J=16.9, 30.0, 6.5 Hz,
1H), 7.41–7.54 (m, 6H), 7.65–7.72 (m, 4H); 13C NMR (75 MHz, CDCl3):
d=20.4 (d, J=18.6 Hz), 123.3 (d, J=103.9 Hz), 128.4 (d, J=12.0 Hz),
131.2 (d, J=9.8 Hz), 131.6, 132.9 (d, J=105.0 Hz), 133.0, 148.0; 31P NMR
(121 MHz, CDCl3): d=24.19; IR (film): n˜ =1184, 970 cmÀ1; elemental
analysis calcd (%) for C15H15OP (242.09): C 74.37, H 6.24; found: C
74.28, H 6.41.
1-tert-Butyldiphenylsilyl-1-dimethylphenylsilylepoxyethane (2j): Yield=
80%; Rf =0.48 (hexanes/AcOEt 20:1); 1H NMR (300 MHz, CDCl3): d=
0.00 (s, 3H), 0.11 (s, 3H), 1.07 (s, 9H), 2.77 (d, J=5.8 Hz, 1H), 3.10 (d,
J=5.8 Hz, 1H), 7.29–7.80 (m, 15H); 13C NMR (75 MHz, CDCl3): d=
À3.4, À3.0, 19.3, 28.5, 44.4, 50.4, 127.5, 127.6, 129.1, 129.4, 133.7, 134.3,
136.2, 136.7; IR (film): n˜ =1250, 1100 cmÀ1; MS (EI, 70 eV): m/z (%): 359
(13) [M +ÀtBu], 333 (41), 317 (2), 281 (20), 255 (52), 223(4), 195 (26),
135 (100), 57 (92); elemental analysis calcd (%) for C26H32OSi2 (416.20):
C 74.94, H 7.74; found: C 75.06, H 7.79.
(Z)-(2-Phenylethenyl)diphenylphosphine oxide (3 f): Yield=59%; Rf =
0.47 (AcOEt); 1H NMR (300 MHz, CDCl3): d=6.31 (dd, J=14.1,
19.4 Hz, 1H), 7.12–7.16 (m, 3H), 7.29–7.46 (m, 11H), 7.52 (dd, J=14.1,
40.4 Hz, 1H), 7.66–7.76 (m, 4H); 13C NMR (75 MHz, CDCl3): d=121.6
(d, J=98.2 Hz), 127.9, 128.5 (d, J=12.1 Hz), 129.2, 130.1, 130.8 (d, J=
9.7 Hz), 131.3, 133.7 (d, J=105.5 Hz), 134.7 (d, J=7.2 Hz), 150.0; 31P
NMR (121 MHz, CDCl3): d=20.84; IR (film): n˜ =1175, 710 cmÀ1; ele-
mental analysis calcd (%) for C20H17OP (304.10): C 78.93, H 5.63; found:
C 79.18, H 5.75.
(Z)-1-tert-Butyldiphenylsilyl-1-trimethylsilyl-1,2-epoxypropane
(2k):
Yield=75%; Rf =0.54 (hexanes/AcOEt 20:1); 1H NMR (300 MHz,
CDCl3): d=À0.21 (s, 9H), 0.98 (s, 9H), 1.57 (d, J=5.4 Hz, 3H), 3.82 (q,
J=5.4 Hz, 1H), 7.30–7.43 (m, 6H), 7.76–7.83 (m, 2H), 7.94–7.99 (m,
2H); 13C NMR (75 MHz, CDCl3): d=0.91, 18.39, 19.51, 28.47, 52,70,
56.86, 127.55, 127.72, 129.20, 129.47, 134.69, 135.09, 136.08, 136.42; IR
(film): n˜ =1250, 1100 cmÀ1; elemental analysis calcd (%) for C22H32OSi2
(368.20): C 71.67, H 8.75; found: C 71.80, H 8.69.
(E)-(2-Phenylethenyl)diphenylphosphine oxide (3g): Yield=71%; Rf =
0.47 (AcOEt); m.p. 166–1688C (from ethanol/H2O); H NMR (300 MHz,
General procedure for the cleavage of epoxysilanes with lithium diphe-
nylphosphide: A solution of the epoxysilanes 1a–m, 1p or the epoxydisi-
lanes 2a,b, 2d,e, 2h (1 mmol) in THF (5 mL) was added dropwise to a
stirred THF solution of lithium diphenylphosphide (1.5 mmol) [prepared
from diphenylphosphine (0.258 mL, 1.5 mmol) and BuLi (0.936 mL, 1.6m
solution in hexane, 1.5 mmol) in THF (5 mL) at 08C under N2 for
30 min]. Starting from less reactive (more hindered) silylepoxides it was
necessary to increase the molar ratio silylepoxide/lithium diphenylphos-
phide to 1:2 for 1n–o, 2 f,i,j and 1:3.5 for 1q, 2c,g,k. The mixture was al-
lowed to warm to room temperature and stirred until TLC indicated
complete reaction (reaction time 2–120 h). Then, methyl iodide (2 mmol)
was added, or hydrolysed with an aq. NH4Cl solution, extracted with di-
ethyl ether and the organic layer dried (MgSO4). Ether was evaporated
and the residue purified by chromatography to give the following com-
pounds.
1
CDCl3): d=6.84 (dd, J=17.4, 22.4 Hz, 1H), 7.35–7.78 (m, 16H); 13C
NMR (75 MHz, CDCl3): d=119.0 (d, J=104.4 Hz), 127.6, 128.5 (d, J=
12.1 Hz), 128.7, 130.0, 131.3 (d, J=9.9 Hz), 131.8 (d, J=1.4 Hz), 132.7 (d,
J=106.0 Hz), 134.9 (d, J=18.0 Hz), 147.4 (d, J=2.8 Hz); 31P NMR
(121 MHz, CDCl3): d=25.46; IR (CH2Cl2): n˜ =1175, 1000 cmÀ1; elemen-
tal analysis calcd (%) for C20H17OP (304.10): C 78.93, H 5.63; found: C
79.03, H 5.49.
(E)-5-Decenyldiphenylphosphine oxide (3h): Yield=72%; Rf =0.48
(AcOEt); 1H NMR (300 MHz, CDCl3): d=0.73 (t, J=7.0 Hz, 3H), 0.89
(t, J=7.1 Hz, 3H), 1.13–1.40 (m, 8H), 2.19–2.31 (m, 4H), 6.15 (dt, J=
7.2, 21.6 Hz, 1H), 7.40–7.53 (m, 6H), 7.63–7.70 (m, 4H); 13C NMR
(75 MHz, CDCl3): d=13.5, 13.8, 22.4, 22.8, 27.5, 28.7, 30.9, 31.7, 128.2 (d,
J=11.6 Hz), 131.5, 131.9 (d, J=9.4 Hz), 132.2 (d, J=1.3.9 Hz), 132.3 (d,
J=96.6 Hz), 147.1 (d, J=9.9 Hz); 31P NMR (121 MHz, CDCl3): d=33.32;
IR (film): n˜ =1178, 815 cmÀ1; elemental analysis calcd (%) for C22H29OP
(340.20): C 77.62, H 8.59; found: C 77.54, H 8.66.
Diphenylvinylphosphine oxide (3a): Yield=65% from 1a and 57% from
1b; Rf =0.36 (AcOEt); 1H NMR (300 MHz, CDCl3): d=6.30 (m, 2H),
6.70 (m, 1H), 7.44–7.57 (m, 6H), 7.67–7.74 (m, 4H); 13C NMR (75 MHz,
CDCl3): d=128.5 (d, J=12.1 Hz), 131.0 (d, J=98.1 Hz), 131.3 (d, J=
9.8 Hz), 131.9 (d, J=1.6 Hz), 132.2 (d, J=88.8 Hz), 134.8; 31P NMR
(E)-(1,2-Diphenylethenyl)diphenylphosphine oxide (3i): Yield=67%;
Rf =0.49 (AcOEt); 1H NMR (300 MHz, CDCl3): d=6.92–7.70 (m, 21H);
Chem. Eur. J. 2004, 10, 4491 – 4497
www.chemeurj.org
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4495

A. Gonzµlez-Nogal et al.
FULL PAPER
13C NMR (75 MHz, CDCl3): d=127.71, 128.2 (d, J=11.8 Hz), 128.7,
128.9, 129.8, 129.9, 130.2, 130.8 (d, J=103.2 Hz), 131.8, 132.3 (d, J=
9.5 Hz), 134.7 (d, J=17.4 Hz), 135.2 (d, J=94.1 Hz), 135.4 (d, J=8.9 Hz),
143.1 (d, J=9.7 Hz); 31P NMR (121 MHz, CDCl3): d=29.51; IR
(CH2Cl2): n˜ =1179, 825 cmÀ1; elemental analysis calcd (%) for C26H21OP
(380.13): C 82.09, H 5.56; found: C 81.94, H 5.68.
Diphenylmethyl-2-propenylphosphonium iodide (4a): see ref. [1].
(E)-1-Hexenyldiphenylmethylphosphonium iodide (4b): Yield=71%
from 1 f and 76% from 1h; m.p. 152–1548C (from EtOH); 1H NMR
(300 MHz, CDCl3): d=0.88 (t, J=7.3 Hz, 3H), 1.33 (m, 2H), 1.50 (m,
2H), 2.49 (m, 2H), 2.88 (d, J=13.4 Hz, 3H), 6.68 (dd, J=16.5, 23.8 Hz,
1H), 6.86 (tt, J=6.6, 16.5 Hz, 1H), 7.27–7.81 (m, 10H); 13C NMR
(75 MHz, CDCl3): d=10.9 (d, J=57.7 Hz), 13.7, 22.2, 29.4, 35.1 (d, J=
18.0 Hz), 109.1 (d, J=85.8), 119.2 (d, J=89.2 Hz), 130.3 (d, J=12.6 Hz),
132.7 (d, J=10.5 Hz), 134.8, 162.8; 31P NMR (121 MHz, CDCl3): d=
17.33; IR (CH2Cl2): n˜ =990 cmÀ1; MS (EI, 70 eV): m/z (%): 283 (16)
[M +], 268 (3), 253 (67), 215 (14), 200 (71), 185 (100), 108 (10), 77 (69);
elemental analysis calcd (%) for C19H24IP (410.07): C 55.62, H 5.90;
found: C 55.58, H 5.78.
(E)-2-Phenyl-1-propenyldiphenylphosphine oxide (3j): Yield: 85% from
1p and 80% from 1q; Rf =0.48 (AcOEt); 1H NMR (300 MHz, CDCl3):
d=2.43 (d, J=1.7 Hz, 3H), 6.35 (d, J=23.6 Hz, 1H), 7.27–7.78 (m,
15H); 13C NMR (75 MHz, CDCl3): d=19.3 d, J=7.6 Hz), 117.9 (d, J=
104.7 Hz), 127.9, 128.6 (d, J=13.7 Hz), 128.7, 130.2, 130.6 (d, J=9.8 Hz),
131.2, 134.0 (d, J=104.7 Hz), 141.5 (d, J=17.0 Hz), 159.0; 31P NMR
(121 MHz, CDCl3): d=22.06; IR (film): n˜ =1178, 815 cmÀ1; elemental
analysis calcd (%) for C21H19OP (318.12): C 79.23, H 6.02; found: C
79.04, H 5.91.
(E)-(2-Phenylethenyl)diphenylmethylphosphonium iodide (4c): Yield=
64%; m.p. 177–1788C (from EtOH); 1H NMR (300 MHz, CDCl3): d=
2.95 (d, J=13.6 Hz, 3H), 6.95 (dd, J=15.7, 26.5 Hz, 1H), 7.08 (t, J=
15.7 Hz, 1H), 7.27–7.91 (m, 15H); 13C NMR (75 MHz, CDCl3): d=11.1
(d, J=58.6 Hz), 106.0 (d, J=89.5 Hz), 119.4 (d, J=90.2 Hz), 128.9, 129.2,
130.2 (d, J=12.5 Hz), 131.8, 132.9 (d, J=10.7 Hz), 133.5, 134.7, 154.7;
31P NMR (121 MHz, CDCl3): d=19.60; IR (CH2Cl2): n˜ =995 cmÀ1; ele-
mental analysis calcd (%) for C21H20IP (430.03): C 58.62, H 4.69; found:
C 58.56, H 4.61.
(E)-(2-Dimethylphenylsilylethenyl)diphenylphosphine
oxide
(3k):
Yield=96% from 2a and 56% from 2b; Rf =0.53 (AcOEt); m.p. 122–
1248C (from CH2Cl2/hexane); 1H NMR (300 MHz, CDCl3): d=0.43 (s,
6H), 6.91 (dd, J=20.4, 31.0 Hz, 1H), 7.31–7.70 (m, 16H); 13C NMR
(75 MHz, CDCl3): d=À3.2, 127.9, 128.5 (d, J=12.0 Hz), 129.5, 131.3 (d,
J=9.8 Hz), 131.7 (d, J=1.6 Hz), 132.3 (d, J=102.8 Hz), 133.8, 136.2,
138.7 (d, J=89.9 Hz), 152.7 (d, J=4.5 Hz); 31P NMR (121 MHz, CDCl3):
d=23.42; IR (CH2Cl2): n˜ =1250, 1190, 1110, 995 cmÀ1; elemental analysis
calcd (%) for C22H23OPSi (362.13): C 72.90, H 6.40; found: C 72.79, H
6.33.
2-Iodoethylidenediphenylmethylphosphorane (5): see ref. [1].
(Z)-1-tert-Butyldiphenylsilyloxy-2-phenylethene (6a): see ref. [1].
2-tert-Butyldiphenylsilyloxypropene
(6b):
Yield=76%;
Rf =0.39
(E)-(2-Trimethylsilylethenyl)diphenylphosphine oxide (3l): Yield=28%;
Rf =0.51 (AcOEt); m.p. 115–1178C (from CH2Cl2/hexane); 1H NMR
(300 MHz, CDCl3): d=0.15 (s, 9H), 6.85 (dd, J=20.4, 31.5 Hz, 1H), 7.27
(dd, J=20.4, 29.6 Hz, 1H), 7.43–7.55 (m, 6H), 7.64–7.72 (m, 4H); 13C
NMR (75 MHz, CDCl3): d=À1.9, 128.5 (d, J=11.9 Hz), 131.3 (d, J=
9.8 Hz), 131.8, 132.5 (d, J=105.0 Hz), 136.8 (d, J=90.3 Hz), 155.2 (d, J=
4.8 Hz); 31P NMR (121 MHz, CDCl3): d=23.42; IR (CH2Cl2): n˜ =1245,
1185, 995 cmÀ1; MS m/z (%): 300 (3) [M +], 285 (9), 227 (13), 202 (58),
185 (13), 73 (100); elemental analysis calcd (%) for C17H21OPSi (300.11):
C 67.97, H 7.05; found: C 68.10, H 7.12.
(hexane); 1H NMR (300 MHz, CDCl3): d=1.07 (s, 9H), 1.85 (d, J=
0.7 Hz, 3H), 3.85 (s, 1H), 3.97 (d, J=0.7 Hz, 1H), 7.42–7.44 (m, 6H),
7.77–7.78 (m, 4H); 13C NMR (75 MHz, CDCl3): d=19.2, 22.7, 26.5, 92.3,
127.6, 129.7, 133.1, 135.4, 155,6; IR (CH2Cl2): n˜ =1100, 795 cmÀ1; MS (EI,
70 eV): m/z (%): 296 (4) [M +], 239 (100), 199 (35), 181 (15), 161 (6), 121
(3), 77 (9), 57 (67); elemental analysis calcd (%) for C19H24OSi (296.16):
C 76.97, H 8.16; found: C 77.04, H 8.23.
1-tert-Butyldiphenylsilyloxy-1-trimethylsilylethene (6c): Yield=52%;
Rf =0.50 (hexane); 1H NMR (300 MHz, CDCl3): d=0.25 (s, 9H), 1.06 (s,
9H), 4.43 (d, J=1.5 Hz, 1H), 4.44 (d, J=1.5 Hz, 1H), 7.41–7.46 (m, 6H),
7.76–7.79 (m, 4H); 13C NMR (75 MHz, CDCl3): d=À2.3, 19.3, 26.4,
(E)-(2-tert-Butyldiphenylsilylethenyl)diphenylphosphine oxide (3m):
1
Yield=45%; Rf =0.54 (AcOEt); H NMR (300 MHz, CDCl3): d=1.10 (s,
105.3, 127.5, 129.5, 133.2, 135.5, 165.8; IR (film): n˜ =1245, 1100, 790 cmÀ1
;
9H), 6.90 (dd, J=20.5, 32.0 Hz, 1H), 7.32–7.85 (m, 21H); 13C NMR
(75 MHz, CDCl3): d=18.3, 27.6, 127.8, 128.5 (d, J=11.9 Hz), 129.6, 131.3
(d, J=9.7 Hz), 131.8, 132.0, 132.5 (d, J=100.8 Hz), 136.1, 142.6 (d, J=
88.1 Hz), 148.8; 31P NMR (121 MHz, CDCl3): d=23.23; IR (film): n˜ =
MS (EI, 70 eV): m/z (%): 297 (9) [M +ÀtBu], 271 (28), 219 (80), 193
(64), 73 (95), 57 (100); elemental analysis calcd (%) for C21H30OSi2
(354.18): C 71.12, H 8.53; found: C 71.24, H 8.47.
1190, 1100, 998 cmÀ1
; elemental analysis calcd (%) for C30H31OPSi
1-tert-Butyldiphenylsilyloxy-1-dimethylphenylsilylethene (6d): Yield=
56%; Rf =0.41 (hexane); 1H NMR (300 MHz, CDCl3): d=0.50 (s, 6H),
0.96 (s, 9H), 4.44 (d, J=1.6 Hz, 1H), 4.48 (d, J=1.6 Hz, 1H), 7.34–7.72
(m, 15H); 13C NMR (75 MHz, CDCl3): d= À3.8, 19.2, 26.3, 107.0, 127.5,
127.7, 129.2, 129.5, 133.0, 134.1, 135.5, 136.6, 164.1; IR (film): n˜ =1250,
1110, 790 cmÀ1; MS (EI, 70 eV): m/z (%): 416 (2) [M +], 359 (31), 281
(63), 255 (21), 195 (22), 179 (32), 135 (28), 105 (13), 77 (23), 57 (100); ele-
mental analysis calcd (%) for C26H32OSi2 (416.20): C 74.94, H 7.74;
found: C 75.06, H 7.81.
(466.19): C 77.22, H 6.70; found: C 77.31, H 6.63.
(E)-(2-Dimethylphenylsilyl-1-propenyl)diphenylphosphine oxide (3n):
1
Yield=73%; Rf =0.53 (AcOEt); H NMR (300 MHz, CDCl3): d=0.43 (s,
6H), 2.16 (dd, J=1.7, 2.9 Hz, 3H), 6.51 (dq, J=1.7, 30.5 Hz, 1H), 7.36–
7.74 (m, 15H); 13C NMR (75 MHz, CDCl3): d=À4.0, 19.6 (d, J=
12.9 Hz), 127.9, 128.5 (d, J=11.9 Hz), 129.4, 130.7 (d, J=9.7 Hz), 130.9
(d, J=89.3 Hz), 131.3, 133.8, 134.5 (d, J=101.4 Hz), 135.9, 167.2 (d, J=
5.1 Hz); 31P NMR (121 MHz, CDCl3): d=20.31; IR (film): n˜ =1250,
1185,1110, 820 cmÀ1
; elemental analysis calcd (%) for C23H25OPSi
(2-Hydroxy-2-dimethylphenylsilyl)propyldiphenylphosphine oxide (7):
1
Yield=40%; Rf =0.55 (AcOEt); H NMR (300 MHz, CDCl3): d=0.37 (s,
(376.14): C 73.37, H 6.69; found: C 73.29, H 6.72.
3H), 0.38 (s, 3H), 1.34 (s, 3H), 2.30 (dd, J=7.6, 15.0 Hz, 1H), 2.75 (t, J=
15.0, 1H), 4.66 (s, 1H), 7.35–7.73 (m, 15H); 13C NMR (75 MHz, CDCl3):
d=À6.4, À6.3, 25.4, 36.0 (d, J=65.8 Hz), 66.4 (d, J=7.9 Hz), 127.7, 128.7
(d, J=11.3 Hz), 130.0, 130.3 (d, J=9.1 Hz), 131.6, 134.2 (d, J=95.2 Hz),
134.5, 135.8; 31P NMR (121 MHz, CDCl3): d=35.37; IR (film): n˜ =3500,
1253, 1178, 1100 cmÀ1; MS (EI, 70 eV): m/z (%): 379 (2) [M +ÀMe], 320
(1), 202 (33), 185 (33), 135 (100); elemental analysis calcd (%) for
C23H27O2PSi (394.15): C 70.02, H 6.90; found: C 69.92, H 6.83.
(E)-(2-Trimethylsilyl-1-propenyl)diphenylphosphine oxide (3o): Yield=
69%; Rf =0.54 (AcOEt); 1H NMR (300 MHz, CDCl3): d=0.11 (s, 9H),
2.13 (dd, J=1.5, 2.7 Hz, 3H), 6.39 (dq, J=30.9, 1.5 Hz, 1H), 7.38–7.47
(m, 6H), 7.66–7.73 (m, 4H); 13C NMR (75 MHz, CDCl3): d=À2.6, 19.3
(d, J=13.4 Hz), 128.4 (d, J=11.8 Hz), 128.8 (d, J=90.2 Hz), 130.6 (d, J=
9.7 Hz), 131.2, 134.5 (d, J=101.0 Hz), 169.3 (d, J=5.5 Hz); 31P NMR
(121 MHz, CDCl3): d=20.32; IR (film): n˜ =1240, 1184, 829 cmÀ1; elemen-
tal analysis calcd (%) for C18H23OPSi (314.13): C 68.76, H 7.37; found: C
68.64, H 7.45.
2-Dimethylphenylsilylpropene (8a): see ref. [4].
(E)-1-tert-Butyldiphenylsilyl-2-trimethylsilylethene (8b): see ref. [3].
(E)-(2-Dimethylphenylsilyl-2-phenyl)ethenyldiphenylphosphine
oxide
(3p): Yield=60%; Rf =0.55 (AcOEt); 1H NMR (300 MHz, CDCl3): d=
0.39 (s, 6H), 6.79 (d, J=18.0 Hz, 1H), 7.62–7.83 (m, 20H); 13C NMR
(75 MHz, CDCl3): d=À3.4, 126.4, 127.3, 127.9, 128.1 (d, J=11.9 Hz),
128.3, 129.5, 130.7 (d, J=9.6 Hz), 130.9, 133.8 (d, J=89.2 Hz), 134.0 (d,
J=100.3 Hz), 134.2, 135.7, 139.5 (d, J=11.6 Hz), 169.1; 31P NMR
(121 MHz, CDCl3): d=18.61; IR (film): n˜ =1248, 1185, 1100, 820 cmÀ1; el-
emental analysis calcd (%) for C28H27OPSi (438.16): C 76.68, H 6.21;
found: C 76.84, H 6.30.
1-tert-Butyldiphenylsilyl-1-trimethylsilylethene (8c): Yield=13%; Rf =
0.54 (hexane); 1H NMR (300 MHz, CDCl3): d=À0.19 (s, 9H), 1.10 (s,
9H), 6.76 (d, J=4.6 Hz, 1H), 6.82 (d, J=4.6 Hz, 1H), 7.34–7.41 (m, 6H),
7.64–7.67 (m, 4H); 13C NMR (75 MHz, CDCl3): d=0.1, 19.0, 28.6, 127.4,
128.9, 136.2, 136.4, 145.1, 149.2; IR (film): n˜ =1250, 1110, 840 cmÀ1; MS
(EI, 70 eV): m/z (%): 338 (1) [M +], 281 (35), 197 (23), 73 (100), 57 (94);
elemental analysis calcd (%) for C21H30Si2 (338.19): C 74.48, H 8.93;
found: C 74.53, H 9.05.
4496
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2004, 10, 4491 – 4497

Cleavage of Silyl- and Disilylepoxides
4491 – 4497
1-tert-Butyldiphenylsilyl-1-dimethylphenylsilylethene (8d): Yield=16%;
Rf =0.45 (hexane); 1H NMR (300 MHz, CDCl3): d=0.35 (s, 6H), 1.06 (s,
9H), 6.74 (d, J=4.5 Hz, 1H), 6.91 (d, J=4.5 Hz, 1H), 7.27–7.76 (m,
15H); 13C NMR (75 MHz, CDCl3): d=À1.5, 0.8, 19.0, 28.6, 127.3, 127.7,
128.8, 128.9, 131.4, 134.0, 135.2, 136.4, 147.2, 147.3; IR (film): n˜ =1248,
1122, 885 cmÀ1; MS (EI, 70 eV): m/z (%): 343 (90) [M +], 265 (18), 197
(100), 181 (17), 135 (78), 105 ( 41), 57 (55); elemental analysis calcd (%)
for C26H32Si2 (400.20): C 77.93, H 8.05; found: C 78.07, H 7.93.
[6] P. F. Hudrlik, D. Peterson, Tetrahedron Lett. 1974, 1133.
[7] P. F. Hudrlik, D. Peterson, J. Am. Chem. Soc. 1975, 97, 1464.
[8] Regiospecific b-opening of a tert-butyldiphenylsilylepoxide was ob-
served by us in its reaction with methyllithium at À258C (ref. [3]).
Other epoxides having hindered silyl groups also underwent b-open-
ing by nucleophiles: B. H. Lipshutz, C. Lindsley, R. Susfalk, T.
Gross, Tetrahedron Lett. 1994, 35, 8999.
[9] A. G. Brook, S. A. Fieldhouse, J. Organomet. Chem. 1967, 10, 235.
[10] A. G. Brook, G. E. LeGrow, D. M. MacRae, Can. J. Chem. 1967, 45,
239.
[11] When we treated the epóxides 1m and 1l with lithium phenylsul-
phide the intermediate of b-cleavage from the tert-butyldiphenylsily-
lepoxide 1m underwent exclusively Brook rearrangement to give
the corresponding silyl enol ether. On the other hand, the intermedi-
ate of the dimethylphenylsilylepoxide 1l experienced only partial
Brook rearrangement leading to a mixture of the respective silyl
enol ether and a-hydroxysilane (unpublished results).
(E)-1-tert-Butyldiphenylsilyl-1-trimethylsilylpropene (8e): Yield=59%;
Rf =0.35 (hexane); 1H NMR (300 MHz, CDCl3): d=À0.12 (s, 9H), 1.06
(s, 9H), 2.18 (d, J=6.6 Hz, 3H), 7.41–7.44 (m, 7H), 7.80–7.84 (m, 4H);
13C NMR (75 MHz, CDCl3): d=1.4, 19.1, 22.2, 28.1, 127.3, 128.7, 136.1,
136.6, 136.8, 155.72; IR (film): n˜ =1253, 1115, 810 cmÀ1; MS (EI, 70 eV):
m/z (%): 337 (2) [M +ÀMe], 295 (100), 279 (1), 221 (12), 197 (78), 159
(45), 135 (55), 73 (6); elemental analysis calcd (%) for C22H32Si2 (352.20):
C 74.93, H 9.15; found: C 75.11, H 8.99.
[12] E. Zbiral, in Organophosphorus Reagent in Organic Synthesis (Ed.:
J. I. G. Cadogan), Academic Press, New York, 1979, pp.223–265.
[13] a) For review, see: I. Fleming, Chimia 1980, 34, 265–271; b) P.
Brownbridge, Synthesis 1983, 1–28, 55–104; c) E. W. Colvin, Silicon
in Organic Synthesis, Butterworths, London, 1981; d) W. P. Weber,
Silicon Reagents for Organic Synthesis, Springer, Berlin, 1983; e) S.
Patai, The Chemistry of Organic Silicon Compounds (Ed.: Z. Rap-
poport), Wiley, Chichester, 1989.
Acknowledgement
We thank the Spanish Ministerio de Ciencia y Tecnología for financial
support (Grant BQU2000–0943).
[14] The hydrolysis of a,b-epoxysilanes and treatment of resulting a,b-di-
hydroxysilanes with KH followed by Me3SiCl led to cis/trans mix-
tures of silyl enol ethers: P. F. Hudrlik, R. H. Schwartz, A. K. Kul-
karni, Tetrahedron Lett. 1979, 2233.
[15] I. Fleming, T. W. Newton, J. Chem. Soc. Perkin Trans. 1 1984, 119.
[16] P. Cuadrado, A. M. Gonzµlez-Nogal, A. Sµnchez, J. Org. Chem.
2001, 66, 1961.
[1] P. Cuadrado, A. M. Gonzµlez-Nogal, Tetrahedron Lett. 1997, 38,
8117.
[2] I. Fleming, T. W. Newton, F. Roessler, J. Chem. Soc. Perkin Trans. 1
1981, 2527.
[3] A. Barbero, P. Cuadrado, I. Fleming, A. M. Gonzµlez, F. J. Pulido,
A. Sµnchez, J. Chem. Soc. Perkin Trans. 1 1995, 1525.
[4] I. Fleming, M. Rowly, P. Cuadrado, A. M. Gonzµlez-Nogal, F. J.
Pulido, Tetrahedron 1989, 45, 413.
[5] A. Barbero, P. Cuadrado, I. Fleming, A. M. Gonzµlez, F. J. Pulido, J.
Chem. Soc. Perkin Trans. 1 1991, 2811.
Received: March 12, 2004
Published online: July 28, 2004
Chem. Eur. J. 2004, 10, 4491 – 4497
www.chemeurj.org
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4497