Acid-catalyzed reactions of (3-(naphthalen-2-yl)-2,2-bis(trimethylsilyl) oxiran. A new synthesis of functional-group-substituted vinylsilanes

Article abstract of DOI:10.1016/j.jorganchem.2011.02.024

The magnesium bromide-diethyl etherate-catalyzed ring-opening of (3-(naphthalen-2-yl)-2,2-bis(trimethylsilyl)oxiran 2 with thiophenols affords (1-trimethylsilylvinyl)sulfides 3 and the (1-bromovinyl)silane 4. Nucleophilic attack occurs regioselectively at the position α- to silicon. The compound 2 has been converted into the (1-trimethylsilylvinyl)amide 5 with an excess of acetonitrile and into the (1-trimethylsilylvinyl)acetate 6 with acetic acid/acetic anhydride. These reactions proceed with catalytic amounts of boron trifluoride-diethylether. Treatment of 2 with acetic acid alone gives naphthaldehyde. The epoxide 2 reacts also with MgBr₂·OEt ₂, MeLi/CuI, HX (XBr or Cl) and LiAlH₄ with nucleophilic attack at the bis(trimethylsilyl)-substituted carbon.

Full text of DOI:10.1016/j.jorganchem.2011.02.024

Journal of Organometallic Chemistry 696 (2011) 1840e1844
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Acid-catalyzed reactions of (3-(naphthalen-2-yl)-2,2-bis(trimethylsilyl)oxiran.
A new synthesis of functional-group-substituted vinylsilanes
*
Kazem D. Safa , Farnaz Behmagham, Khatereh Ghorbanpour
Organosilicon Research Laboratory, Faculty of Chemistry, University of Tabriz, 51664 Tabriz, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
The magnesium bromide-diethyl etherate-catalyzed ring-opening of (3-(naphthalen-2-yl)-2,2-bis(tri-
methylsilyl)oxiran 2 with thiophenols affords (1-trimethylsilylvinyl)sulfides 3 and the (1-bromovinyl)
silane 4. Nucleophilic attack occurs regioselectively at the position a- to silicon. The compound 2 has
been converted into the (1-trimethylsilylvinyl)amide 5 with an excess of acetonitrile and into the
(1-trimethylsilylvinyl)acetate 6 with acetic acid/acetic anhydride. These reactions proceed with catalytic
amounts of boron trifluoride-diethylether. Treatment of 2 with acetic acid alone gives naphthaldehyde.
The epoxide 2 reacts also with MgBr2$OEt2, MeLi/CuI, HX (X]Br or Cl) and LiAlH4 with nucleophilic
attack at the bis(trimethylsilyl)-substituted carbon.
Received 9 October 2010
Received in revised form
6 February 2011
Accepted 18 February 2011
Keywords:
Bis(trimethylsilyl)epoxides
Vinylsilylsulfides
Peterson reaction
Vinylsilanes
Ó 2011 Elsevier B.V. All rights reserved.
Acid-catalyzed ring-opening
1. Introduction
2. Results and discussion
2,2-Bis(trimethylsilyl)oxirans [1] are valuable reagents for the
production of organosilicon compounds [2]. Ring-opening of
epoxides with thiols is used widely in pharmaceutical and natural
product chemistry [3]. Recent approaches for the synthesis of vin-
ylsulfides have involved nucleophilic ring-opening of epoxysilanes
with lithium thiophenolate, in a solvent and in the presence of
a Lewis acid [4]. Although the behavior of trimethylsilylepoxides
toward nucleophiles has been widely studied [5e7], there have
been fewer references to the reactivity of bis(trimethylsilyl)epox-
ides. These are versatile intermediates that react with a wide variety
The Peterson reaction gives 1,1-disilylalkenes with non-enolis-
able aldehydes and ketones. In previous work, we prepared various
1,1-disilylalkenes from aldehydes and treated them with elec-
trophilic reagents. 1,1-Bis(trimethylsilyl)-2-(2-naphthyl)ethene 1
was prepared from the reaction of [tris(trimethylsilyl)methyl]lit-
hium, (Me3Si)3CLi, with 2-naphthaldehyde via the Peterson
protocol [10e12]. Epoxidation of this compound with m-chlor-
operoxybenzoic acid (MCPBA) in CH2Cl2 at room temperature gave
(3-(naphthalen-2-yl)-2,2-bis(trimethylsilyl)oxiran 2 (Scheme 1).
Previously vinylsulfides were synthesized from epoxysilanes;
we now report the synthesis of (1-trimethylsilylvinyl)sulfides by
the magnesium bromide-diethyl etherate-catalyzed ring-opening
of bis(trimethylsilyl)epoxides. Magnesium bromide-diethyl ether-
ate has found many applications as a mild Lewis acid to facilitate
various synthetic organic transformations including ring-opening
of epoxides with thiols under mild conditions [3]. The epoxide 2
reacted with various thiophenols (Table 1) in the presence of
of reagents via ring-opening a- to silicon. We have recently reported
the synthesis and reactivity of 1,4-bis[2,2-bis(trimethylsilyl)eth-
enyl]benzene and a 2,2-bis(trimethylsilyl)oxiran [8].
Given the utility of vinylsilylsulfides in synthesis [9] and the
availability of 1,1-bis(trimethylsilyl)ethenes, the development of
a method for conversion of bis(trimethylsilyl)ethenes into vinyl-
silylsulfides via bis(trimethylsilyl)epoxides would be of value. In this
paper we describe the ring-opening of (3-(naphthalen-2-yl)-2,2-bis
(trimethylsilyl)oxiran 2 with ArSH/MgBr2$OEt2 to give (1-trime-
thylsilylvinyl)sulfides. Treatment of 2 with CH3CN/BF3.Et2O, AcOH/
Ac2O/BF3.Et2O, HX (X]Br or Cl), MeLi/CuI or LiAlH4 led to the
formation of (1-trimethylsilylvinyl)acetamide, (1-trimethylsilylvinyl)
acetate, (1-halovinyl)silanes and alkenylsilanes, respectively.
MgBr2$OEt2 in CH2Cl2 at room temperature via a-ring opening and
subsequent elimination of the silyl group and oxygen to give the
(1-trimethylsilylvinyl)sulfides 3. In these reactions both isomers
(Z and E) have been formed. The formation of Z-alkene is most
likely favored due to pronounced differences in eclipsing interac-
tions between the two possible conformations for syn elimination
[5,13]. However, in the presence of two bulky groups ꢀSiMe3
and ꢀSAr approximately equal amounts of E and Z isomers are
formed. To prove the above results, we attributed the phenylthio
* Corresponding author. Tel.: þ98 411 3393124; fax: þ98 411 3340191.
E-mail address: dsafa@tabrizu.ac.ir (K.D. Safa).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.02.024

K.D. Safa et al. / Journal of Organometallic Chemistry 696 (2011) 1840e1844
1841
Acid-catalyzed reactions yielded products derived from
cleavage of the CeO bond in the direction expected to produce the
more stable cation. The products in these reactions were consis-
tent with a-cleavage of the a,b-epoxides and only bromohydrins
were obtained from epoxysilanes [15]. However treatment of the
epoxide 2 with MgBr2$OEt2 at room temperature produced the
(1-bromovinyl)silane 4 directly (Table 1). Formation of 4 showed
that Peterson olefination took place after or concurrently with the
addition of Lewis acid.
It has been reported [16e18] that when epoxides were treated
with CH3CN in the presence of BF3$Et2O the initial products were
oxazolines and that subsequent hydrolysis yielded hydroxyamides.
Treatment of these hydroxyamides with KH in THF gave the
enamides. However, in the case of 2, Peterson-type olefination after
or concurrently with the addition of CH3CN/BF3$OEt2 gave the
(1-trimethylsilylvinyl)amide 5 regioselectively in one step without
addition of KH or other reagents (Scheme 3). This reaction was
carried out by stirring equimolar amounts of the epoxide 2 and
boron trifluoride-ether, with an excess of acetonitrile as solvent, for
24 h at room temperature.
Scheme 1. Preparation of (3-(naphthalen-2-yl)-2,2-bis(trimethylsilyl)oxiran (2).
group elimination reaction in 3a (Scheme 2) [14]. The elimination
of the phenylthio from a mixture of the (Z) and (E)-1-phenylthio-1-
trimethylsilyl-2-naphthylethene (3a) proceeded smoothly with
lithium naphthalenide to give the corresponding vinylsilane (9). In
this elimination reaction, the yield of trans isomer was 56%. Namely
the Z isomer is more than the E isomer. These results have been
confirmed by 1H NMR and GC-mass spectra (Table 2).
Compound 2 reacted with 3-methoxythiophenol in the presence
of MgBr2$OEt2 for 18 h to give the unexpected product 3d (Table 1). In
this reaction, the yield of the (1-bromovinyl)silane 4, itself a valuable
reagent in organic chemistry, is more than that of compound 3d.
Treatment of 2 with MgBr2$OEt2 led to the formation of 4.
Table 1
Reaction of 2 with thiophenols and summary of experimental conditions and yields.
.
Entry
ArSH
Product
Time(h)
Yield a(%)
(3) (Z:E)
(4) (Z)
24
1
2
(3a)
(3b)
2
4
76 (53:47)
70 (50.4:49.6)
30
35
3
4
(3c)
4
65 (55:45)
(3d)
18
18
40
60
69
5
_
(4)
_
a
Yields obtained by GC-Mass spectrometry.

1842
K.D. Safa et al. / Journal of Organometallic Chemistry 696 (2011) 1840e1844
Scheme 3. Treatment of compound 2 with acetonitrile.
Scheme 2. Elimination reaction of compound 3a.
provide a general regioselective method for preparation of (1-hal-
ovinyl)silanes.
Treatment of 2 with acetic acid containing 20% acetic anhydride
and 1% BF3$OEt2 at room temperature gave the acetate 6 directly. In
this system, trimethylsilanol was eliminated spontaneously with
BF3-catalyzed oxide ring opening to yield the vinyl ester in a single
step. However when 2 was treated with acetic acid in the absence
of BF3$OEt2 and acetic anhydride, only the unexpected product
naphthaldehyde was observed at 80 ꢁC. Thus Lewis acid BF3 cata-
lyzed the cleavage of a silicon-carbon bond and the formation of
4. Experimental
4.1. Solvents and reagents
The reactions were carried out under dry argon. Solvents were
dried by standard methods. Substrates for the preparation of tris
(trimethylsilyl)methyllithium, viz. Me3SiCl (Merck), Li (Merck),
CHCl3 (Merck), and for the preparation of (3-(naphthalen-2-yl)-2,2-
bis(trimethylsilyl)oxiran 2, viz. 2-naphthaldehyde (Merck) and
MCPBA (Acros) were used as received.
a positive charge in position
nucleophilic attack [19,20].
a- to the trimethylsilyl groups for the
Treatment of the epoxide 2 with MeLi/CuI gave the methylation
product 7 (Scheme 4, Table 2). But the major product was identified
by FTIR, NMR (1H and 13C) and mass spectrometry as the bis(tri-
methylsilyl)-derivative 1.
4.2. Spectra
As pointed out above the (1-bromovinyl)silane 4 could be
prepared by the reaction of 2 with the magnesium bromide-diethyl
etherate. An alternative method for synthesis of (halovinyl)silanes
is by reactions of epoxides with hydrogen halides [1]. Reaction of 2
with HX (X]Br or Cl) in aq. THF under reflux gave the (1-halovinyl)
silanes 4 and 8 (Scheme 5). The mechanism of this reaction has
been discussed [5,8,21].
The 1H and 13C NMR spectra were recorded with a Bruker FT-
400 MHz instrument at room temperature and CDCl3 as a solvent.
The mass spectra were obtained with a GC-mass Agilent quadru-
pole mode 5973N instrument, operating at 70 eV. FTIR spectra were
recorded on a Bruker-Tensor 270 spectrometer. Elemental analyses
were carried out with an elementar vario EL III instrument.
We wished to prepare the b-hydroxysilane from the reduction of
4.3. Synthesis of products 1e9
2 with lithium aluminum hydride in diethyl ether but Peterson
olefination was found to occur concurrently to give the vinylsilane 9
(Scheme 6). The extremely high stereoselectivity of the reaction
(only trans was formed) is noteworthy.
4.3.1. Synthesis of (3-(naphthalen-2-yl)-2,2-bis(trimethylsilyl))
oxiran (2)
A mixture of vinylsilane 1 (2.00 g, 6.71 mmol), MCPBA (75% w/w
pure) and CH2Cl2 (75 ml) was stirred at room temperature for 24 h.
The mixture was washed with aq. NaHCO3 (5 ꢂ 40 ml), water
(40 ml), brine (40 ml) and the organic layer was dried (MgSO4).
Solvent was evaporated and the residue purified by column chro-
matography (1:4 n-hexane:ethyl acetate) to give 2 as a yellow
liquid. Yield 78%. Rf ¼ 0.6. FTIR (KBr, cmꢀ1): 3054 (CH, Ar), 2957
(CH), 1506 and 1388 (Ar), 1252, 930 and 846 (CeSi), 1107 (CeO); 1H
3. Conclusion
This work demonstrates that ring opening of the bis(trime-
thylsilyl)epoxide 2 in the presence of catalytic amounts of Lewis
acids occurred regioselectivelyat the position a- tothe trimethylsilyl
groups. Epoxidation of 1,1-bis(trimethylsilyl)-2-(2-naphthyl)ethene
1 with MCPBA in CH2Cl2 gave (3-(naphthalen-2-yl)-2,2-bis(trime-
thylsilyl)oxiran 2 that served as precursor for the preparation of
a series of valuable compounds. Treatment of 2 with thiols in the
presence of MgBr2$OEt2 led to the preparation of (1-trimethylsi-
lylvinyl)sulfides 3 and (1-bromovinyl)silane 4. These reactions
NMR (400 MHz, CDCl3):
d
ꢀ0.21 and 0.20 (s,18 H, SiMe3), 4.33 (s,1H,
HCeO), 7.45e7.84 (m, 7H, Ar); 13C NMR (CDCl3):
d
ꢀ3.01 and ꢀ1.33
(SiMe3), 54.67 and 60.77 (CeO), 123.91e134.90 (Ar); m/z (EI): 314
(41%, [M]þ), 147 (100%), 148 (16%), 198 (31%), 73 (64%, [SiMe3]þ).
Anal. Calc. forC18H26OSi2: C, 68.8; H, 8.2. Found: C, 68.9; H, 7.9%.
4.3.2. General procedure for the preparation of (1-trimethylsilylvinyl)
sulfides 3
Table 2
A mixture of the epoxide 2 (0.5 mmol), thiol (0.6 mmol),
anhydrous dichloromethane (2e3 ml) and MgBr2$OEt2 (0.2 mmol)
was stirred and the course of the reaction was monitored by TLC
until the starting materials had completely disappeared. The
mixture was diluted in dichloromethane (10 ml) and washed twice
with water (10 ml). The organic phase was dried over Na2SO4, the
Treatment of 2 with acetic acid under various conditions.
.
Entry Reagents
Temperature Time Product
Yield a(%)
(ꢁC)
(h)
1
2
3
CH3COOH
CH3COOH
CH3COOH/Ac2O r.t
80
0
2
24
2
Naphthaldehyde 62
e
e
(6)
70
BF3$OEt2
a
Scheme 4. Reaction of 2 with MeLi/CuI.
Yields obtained by PTLC.

K.D. Safa et al. / Journal of Organometallic Chemistry 696 (2011) 1840e1844
1843
residue was purified by preparative TLC on silica gel to give yellow
solid (69%). The NMR and GC-mass spectra of 4 have been shown in
4.3.8.2.
4.3.4. Elimination reaction of 3a
Li (10 mg, 3 mmol) and naphthalene (50 mg, 0.8 mmol) were
mixed under argon atmosphere in THF (2 ml) and the mixture was
stirred at 0 ꢁC for 2 h. Then (1-trimethylsilylvinyl)sulfide 3a (34 mg,
0.1 mmol) in THF (1 ml) was added, and the mixture was stirred for
1 h. Ether (20 ml) and water (3 drops) were added and the mixture
was washed with water. The organic layer was dried (MgSO4) and
the solvent was evaporated to give crude product. The crude product
was purified by TLC on silica gel to give a yellow oil (50%). 1H NMR
Scheme 5. Reaction of 2 with HX (X]Cl or Br).
solvent was removed at reduced pressure, and the product was
purified by preparative TLC on silica gel.
4.3.2.1. Analytical data for 3a. White solid (76%): (Rf ¼ 0.17
n-hexane, m.p. 84e86 ꢁC), FTIR (KBr, cmꢀ1): 3053 (CH, vinyl), 2954
(CH, Ar), 2924 (CH),1649-1471 (C]C, Ar),1243, 930 and 837 (CeSi);
(400 MHz, CDCl3):
vinyl), 7.02 (d, 1H, J ¼ 19.12 Hz, vinyl), 7.41e7.82 (m, 7H, Ar).
d
0.19 (s, 9H, SiMe3), 6.58 (d, 1H, J ¼ 19.12 Hz,
1H NMR (400 MHz, CDCl3):
vinyl, 12H, Ar); 13C NMR (CDCl3):
d 0.14 (s, 9H, SiMe3), 7.20e8.08 (1H,
d
ꢀ1.65 (SiMe3), 124.75e135.95
(C]C, Ar), 145.13 (CeS); m/z (EI): 335 (28% [M þ 1]þ), 334 (100%
[M]þ), 167 (60%), 73 (53%, [SiMe3]þ). Anal. Calc. For C21H22SSi: C,
75.4; H, 6.6. Found: C, 75.1; H, 6.8%.
4.3.5. Reaction of 2 with CH3CN
Equimolar amounts (0.32 mmol) of 2 and boron trifluoride-
ether in acetonitrile as solvent (2e3 ml) were stirred at room
temperature for 24 h. The mixture was poured into aqueous sodium
hydrogen carbonate and the dichloromethane extract was washed,
then dried (Na2SO4). Solvent was evaporated and the residue
separated by preparative TLC on silica gel (10:1 n-hexane:ethyl
acetate) to give a yellow solid 5 (85%, Rf ¼ 0.34, m.p.117e119 ꢁC).
FTIR (KBr, cmꢀ1): 3245 (NH), 3050 (CH, vinyl), 2924 (CH, Ar), 2853
(CH), 1644 (C]O), 1597 and 1523 (C]C, Ar),1241, 992 and 840
4.3.2.2. Analytical data for 3b. Colorless oil (70%): (Rf ¼ 0.16
n-hexane), FTIR (KBr, cmꢀ1): 3054 (CH, vinyl), 3018 (CH, Ar), 2957
and 2925 (CH), 1629e1462 (C]C, Ar), 1248, 933 and 840 (CeSi); 1H
NMR (400 MHz, CDCl3):
d
0.09 (s, 9H, SiMe3), 2.36 (s, 3H, CH3)
ꢀ1.53 (SiMe3),
7.19e7.88 (1H, vinyl, 11H, Ar); 13C NMR (CDCl3):
d
20.19 (CH3), 124.76e132.67 (C]C, Ar), 144.05 (CeS); m/z (EI): 349
(29% [M þ 1]þ), 348 (100% [M]þ), 275 (24% [MeSiMe3]þ), 181 (46%),
73(59%, [SiMe3]þ). Anal. Calc. For C22H24SSi: C, 75.9; H, 6.9. Found:
C, 76.1; H, 6.9%.
(CeSi), 1130 (CN); 1H NMR (400 MHz, CDCl3):
1.98 (s, 3H, methyl), 6.31 (s, 1H, vinyl), 7.31e7.87 (m, 7H, Ar, 1H,
d 0.32 (s, 9H, SiMe3),
NH); 13C NMR (CDCl3):
d
ꢀ0.51 (SiMe3), 22.12 (CH3), 122.13e138.72
(C]C, Ar), 166.73 (C]O); m/z (EI): 283 (5%, [M]þ), 268 (100%,
[MeMe]þ), 116 (13%), 209(9%), 73(7%, [SiMe3]þ). Anal. Calc. for
C17H21NOSi: C, 72.0; H, 7.4;N, 4.9. Found: C, 72.0; H, 7.3;N, 5.1%.
4.3.2.3. Analytical data for 3c. Yellow oil (65%): (Rf ¼ 0.4 n-hexane),
FTIR (KBr, cmꢀ1): 3045 (CH, vinyl), 2924 (CH, Ar), 2853 (CH),
1633e1467 (C]C, Ar), 1256, 967 and 841 (CeSi), 812 (CeCl); 1H
4.3.6. Reaction of 2 with CH3COOH
NMR (400 MHz, CDCl3):
d 0.06 (s, 9H, SiMe3), 7.15e8.04 (1H, vinyl,
11H, Ar); 13C NMR (CDCl3):
d
ꢀ1.71 (SiMe3), 122.46e132.75 (C]C,
A mixture of 2 (1 mmol), 5 mmol of acetic acid, 20% anhydride
acid and 1% BF3$OEt2 was stirred at room temperature for 2 h, then
extracted with CH2Cl2. The organic phase was washed with water,
then dried over Na2SO4. Solvent was evaporated and the product
purified by preparative TLC on silica gel (10:1 n-hexane:ethyl
acetate) to give a white solid 6 (70%, Rf ¼ 0.68, m.p.65e66 ꢁC). FTIR
(KBr, cmꢀ1): 3053 (CH, vinyl), 2957 (CH, Ar), 2925 (CH),1743 (C]O),
1621 (C]C), 1496 and 1462 (Ar), 1248, 967 and 838 (CeSi), 1208
Ar), 143.31 (CeS); m/z (EI): 370 (43% [M þ 2]þ), 369(29% [M þ 1]þ),
368 (100% [M]þ), 201 (32%), 73(59%, [SiMe3]þ). Anal. Calc. For
C21H21ClSSi: C, 68.4; H, 5.7. Found: C, 68.1; H, 5.5%.
4.3.2.4. Analytical data for 3d. Yellowish liquid (40%): (Rf ¼ 0.24
10:1 n-hexane:ethyl acetate), FTIR (KBr, cmꢀ1): 3054 (CH, vinyl),
2956 (CH, Ar), 2924 (CH), 1636 and 1470 (C]C, Ar); 1H NMR
(CO); 1H NMR (400 MHz, CDCl3):
d 0.27 (s, 9H, SiMe3), 2.23 (s, 3H
(400 MHz, CDCl3):
d
3.33 (d, 2H, J ¼ 7.04 Hz, CH2), 3.71 (s, 6H, CH3),
methyl), 6.44 (s, 1H, vinyl), 7.26e7.91 (m, 7H, Ar); 13C NMR (CDCl3):
4.71 (t, 1H, J ¼ 8 Hz, CH), 6.79e7.80 (m, 15H, Ar); 13C NMR (CDCl3):
d
ꢀ2.00 (SiMe3), 19.87 (CH3), 122.96e132.33 (C]C, Ar), 155.93
d
41.52 (CH2), 54.22 (CH), 58.38 (CH3), 112.75e158.68 (Ar); m/z (EI):
(CeO), 168.10 (C]O); m/z (EI): 284 (30%, [M]þ), 269 (37%,
[MeMe]þ), 242 (81%, [MeCH3CO]þ), 73(100%, [SiMe3]þ). Anal. Calc.
for C17H20O2Si: C, 71.8; H, 7.0. Found: C, 72.0; H, 7.2%.
432 (7%, [M]þ), 293 (78%, [MeSC6H4OMe]þ), 153 (28%,
[CH2SC6H4OMe]þ), 139 (28%, [SC6H4OMe]þ). Anal. Calc. For
C26H24O2S2: C, 72.2; H, 5.5. Found: C, 72.4; H, 5.8%.
4.3.7. Reaction of 2 with MeLi/CuI
4.3.3. Reaction of 2 with MgBr2$OEt2
To a mixture of 0.49 g (5.14 mmol) CuI in 10 ml anhydrous ether
at ꢀ45 ꢁC was added dropwise a solution of methyllithium, made
by the addition of 0.32 ml (5.14 mmol) MeI in 5 ml anhydrous ether
to 72 mg (10.3 mmol) Li in 10 ml ether. The mixture was stirred for
1 h at ꢀ45 ꢁC. Then a solution of 200 mg (0.64 mmol) of 2 in ether
(5 ml) was added dropwise. The mixture was stirred for 2 h
at ꢀ45 ꢁC, then for 23 h as the solution was allowed to warm to
room temperature. It was treated with 20 ml saturated NaHCO3
then water, and the organic layer was dried (MgSO4), and concen-
trated. The residue was separated by preparative TLC on silica gel
(n-hexane) to give the bis(trimethylsilyl)ethene 1 (89%, Rf ¼ 0.44)
and a brown oil 7 (10%, Rf ¼ 0.12). FTIR (KBr, cmꢀ1): 3054
(CH, vinyl), 2956 (CH, Ar), 2924 (CH), 1647-1458 (C]C, Ar), 1244,
A mixture of bis(trimethylsilyl)epoxide 2 (0.5 mmol), anhydrous
dichloromethane (2e3 ml) and MgBr2$OEt2 (0.2 mmol) was stirred
for 18 h. TLC showed that by this time the reaction was complete.
Further dichloromethane (10 ml) was added and the mixture was
washed twice with water (10 ml). The organic phase was dried over
Na2SO4, the solvent was removed at reduced pressure, and the
961 and 837 (CeSi); 1H NMR (400 MHz, CDCl3):
SiMe3), 1.25 (s, 3H, CH3), 7.25 (s, 1H, vinyl), 7.44e7.87 (7H, Ar); 13C
d 0.31 (s, 9H,
Scheme 6. Reduction of 2 with LiAlH4.

1844
K.D. Safa et al. / Journal of Organometallic Chemistry 696 (2011) 1840e1844
NMR (CDCl3):
d
ꢀ2.20 (SiMe3), 28.69 (CH3), 122.31e142.58 (C]C,
solid (67%, Rf ¼ 0.67, m.p.52e54 ꢁC). FTIR (KBr, cmꢀ1): 3053 (CH,
vinyl), 2954 (CH, Ar), 2925 (CH), 1603 (C]C), 1601 and 1405 (C]C,
Ar); m/z (EI): 240 (78%, [M]þ), 225 (100%, [MeMe]þ), 185 (95%), 165
(41%), 73 (65%, [SiMe3]þ). Anal. Calc. For C16H20Si: C, 80.0; H, 8.3.
Found: C, 79.7; H, 8.1%.
Ar), 1247, 985 and 833 (CeSi); 1H NMR (400 MHz, CDCl3):
d 0.19
(s, 9H, SiMe3), 6.58 (d, 1H, J ¼ 19.12 Hz, vinyl), 7.02 (d, 1H,
J ¼ 19.12 Hz, vinyl), 7.41e7.82 (m, 7H, Ar); 13C NMR (CDCl3):
4.3.8. Reaction of 2 with HX (X]Cl or Br)
d
ꢀ2.20 (SiMe3), 122.32e142.58 (C]C, Ar); m/z (EI): 226 (58%,
A mixture of 2 (100 mg, 0.32 mmol), HX (2 mol dmꢀ3; 5 ml) and
THF (5 ml) was stirred at 70 ꢁC. After 18 h the reaction mixture was
washed with saturated aq. Na2CO3 (2 ꢂ 10 ml), aq. Na2S2O3
(1 mol dmꢀ3, 10 ml), water (10 ml) and brine (10 ml). The organic
layer was dried (MgSO4) and solvent evaporated to give a residue
which was purified by preparative TLC on silica gel (15:1 n-hex-
ane:ethyl acetate) to give yellow solids 4 (92%) and 8 (93%).
[M]þ), 211 (100%, [MeMe]þ), 195 (48%), 59 (23% [SiMe2]þ), 212
(20%). Anal. Calc. For C15H18Si: C, 79.6; H, 7.9. Found: C, 79.3; H,
8.1%.
Acknowledgment
We thank Dr. J. D. Smith for his helpful comments.
4.3.8.1. Analytical data for 8. (Rf
¼
0.82 15:1 n-hexane:ethyl
acetate, m.p.42e44 ꢁC), FTIR (KBr, cmꢀ1): 3055 (CH, vinyl), 2961
(CH, Ar), 2926 (CH), 1586e1409 (C]C, Ar), 1259, 931 and 809
References
(CeSi); 1H NMR (400 MHz, CDCl3):
d 0.29 (s, 9H, SiMe3), 7.01 (s, 1H,
[1] D.M. Hodgson, P.J. Comina, Chem. Commun. (1996) 755e756.
[2] P. Pawluc, G. Hreczycho, B. Marciniec, J. Org. Chem. 71 (2006) 8676e8679.
[3] M.M. Mojtahedi, M.S. Abaee, M. Bolourtchian, H. Abbasi, Phosphorus, Sulfur,
and Silicon 182 (2007) 905e910.
[4] P. Cuadrado, A.M. González-Nogal, Tetrahedron Lett. 41 (2000) 1111e1114.
[5] D.M. Hodgson, P.J. Comina, M.G.B. Drew, J. Chem. Soc. Perkin Trans. 1 (1997)
2279e2289.
vinyl), 7.26e8.19 (m, 7H, Ar); 13C NMR (CDCl3):
d
ꢀ4.15 (SiMe3),
124.13e133.52 (CeCl, C]C, Ar); m/z (EI): 262 (37%, [M þ 2]þ), 260
(100%, [M]þ), 93 (91%), 95 (33%,), 152 (24%). Anal. Calc. For
C15H17ClSi: C, 69.2; H, 6.5. Found: C, 69.4; H, 6.7%.
[6] P.F. Hudrlik, D. Ma, R.S. Bhamidipati, A.M. Hudrlik, J. Org. Chem. 61 (1996)
8655e8658.
[7] R. Boukherroub, G. Manuel, J. Organomet. Chem. 604 (2000) 141e149.
[8] K.D. Safa, K. Ghorbanpour, A. Hassanpour, S. Tofangdarzadeh, J. Organomet.
Chem. 694 (2009) 1907e1911.
[9] F. Cooke, R. Moerck, J. Schwindeman, P. Magnus, J. Org. Chem. 45 (1980)
1046e1053.
[10] K.D. Safa, A. Hassanpour, S. Tofangdarzadeh, J. Organomet. Chem. 693 (2008)
3622e3626.
[11] K.D. Safa, M. Namvari, A. Hassanpour, S. Tofangdarzadeh, J. Organomet. Chem.
694 (2009) 2448e2453.
[12] K.D. Safa, S. Paymard Samani, Sh. Tofangdarzadeh, A. Hassanpour, J. Organomet.
Chem. 693 (2008) 2004e2008.
4.3.8.2. Analytical data for 4. (Rf ¼ 0.83 15:1 n-hexane:ethyl
acetate, m.p. 58e60 ꢁC), FTIR (KBr, cmꢀ1): 3054 (CH, vinyl), 2951
(CH, Ar), 2859 (CH), 1586e1409 (C]C, Ar), 1249, 907 and 827
(CeSi); 1H NMR (400 MHz, CDCl3):
d 0.35 (s, 9H, SiMe3), 7.29 (s, 1H,
vinyl), 7.41e7.90 (m, 7H, Ar); 13C NMR (CDCl3):
d
ꢀ2.79 (SiMe3),
125.17e137.19 (CeBr, C]C, Ar); m/z (EI): 308 (24%, [M þ 2]þ), 306
(100%, [M]þ), 304 (97%, [M ꢀ 2]þ), 209 (40%), 139 (92%), 136 (89%),
73 (30%, [SiMe3]þ). Anal. Calc. for C15H17BrSi: C, 58.8; H, 5.5. Found:
C, 58.5; H, 5.5%.
[13] P.F. Hudrlik, E.L.O. Agwaramgbo, M. Anne, A.M. Hudrlik, J. Org. Chem. 54 (1989)
5613e5618.
[14] T. Mamdai, M. Kohama, H. Sato, M. Kawada, J. Tsuji, Tetrahedron 46 (1990)
4553e4562.
[15] P.F. Hudrlik, R.N. Misra, G.P. Withers, A.M. Hudrlik, R.J. Rona, J.P. Arcoleo,
Tetrahedron Lett. 18 (1976) 1453e1456.
[16] P.F. Hudrlik, A.N. Hudrlik, R.J. Rona, R.N. Misra, G.P. Withers, J. Am. Chem. Soc.
99 (1977) 1993e1996.
4.3.9. Reduction of 2 with LiAlH4
To 100 mg (2.44 mmol) of LiAlH4 in 25 ml of anhydrous ether at
0 ꢁC was added 200 mg (0.64 mmol) of 2. The stirred mixture was
allowed to warm to room temperature during 6 h. It was then
cooled in a N2/ethyl acetate bath (ꢀ78 ꢁC), and cold aqueous
NaHCO3 (10 ml) was added dropwise. The mixture was allowed to
warm to room temperature. Ether was added, the organic layer
was separated, and the aqueous layer was extracted with ether
(2 ꢂ 20 ml). The combined organic layers were dried (MgSO4) and
solvent was evaporated. The residue was separated by preparative
TLC on silica gel (10:1 n-hexane:ethyl acetate) to give 9 as a white
[17] R.A. Wohl, J. Cannie, J. Org. Chem. 38 (1973) 1787e1790.
[18] J.R. Smith, R.O.C. Narman, M.R. Stillings, J. Chem. Soc. Perkin Trans. 1 (1975)
1200e1202.
[19] M.C. Croudace, N.E. Schore, J. Org. Chem. 46 (1981) 5359e5363.
[20] G. Manuel, R. Boukherroub, J. Organomet. Chem. 447 (1993) 167e175.
ꢀ
[21] P. Pawluc, M. Madalska, G. Hreczycho, B. Marciniec, Synthesis (2008)
3687e3691.