Stereocontrolled formation of vinylsilanes via homolytic substitution at silicon

Article abstract of DOI:10.1055/s-2004-829186

Intramolecular homolytic substitution reactions at silicon by vinyl radicals are described. The reaction can be used for the formation of 5- and 6-membered cyclic alkoxysilanes bearing a vinyl silane functionality. These processes provide a new entry into highly substituted vinyl silanes. The reactions occur with moderate to excellent selectivities.

Full text of DOI:10.1055/s-2004-829186

2226
SPECIAL TOPIC
Stereocontrolled Formation of Vinylsilanes via Homolytic Substitution at
Silicon
S
tereocontrolledF
n
ormation of
V
inylsilanesreas Blum, Wilfried Hess, Armido Studer*1
Fachbereich Chemie, Universität Marburg, Hans-Meerwein-Straße, 35032 Marburg, Germany
Fax +49(251)8336523; E-mail: studer@uni-muenster.de
Received 17 May 2004
We decided to study 5-exo-type cyclizations first. The re-
Abstract: Intramolecular homolytic substitution reactions at sili-
con by vinyl radicals are described. The reaction can be used for the
formation of 5- and 6-membered cyclic alkoxysilanes bearing a vi-
nyl silane functionality. These processes provide a new entry into
quested vinyl radicals can readily be generated via in-
tramolecular addition of carbon-centered radicals to triple
bonds.8d,10 The syntheses of the radical precursors are pre-
highly substituted vinyl silanes. The reactions occur with moderate sented in Scheme 2. Bromoaldehyde 1 was prepared from
the corresponding alcohol11 via Swern oxidation. Li-
to excellent selectivities.
acetylide addition at low temperature provided the sec-
ondary alcohols 2–5 in moderate to good yields. All com-
pounds discussed in the present paper were prepared as
racemates. However, it is important to note that acetylide
additions to aldehydes can meanwhile be performed with
high enantioselectivities.12 Silylation of the alcohols using
ClSi(Ph)2SnMe313 eventually afforded the stannylated si-
lyl ethers 6–9, ready to be used in homolytic substitution
reactions.
Key words: radical chemistry, silicon, stereoselective synthesis,
vinyl silanes, tin
Intramolecular homolytic substitution reactions (SHi) at
carbon using C-centered radicals are not well established.2
However, the analogous reactions at heavier group XIV
elements have been studied in more detail.3 These pro-
cesses have been successfully used for the construction of
Si-,4 Ge-4a,c,5 and Sn-containing4a,c,6 heterocycles. Some
years ago we reported on the SHi reaction of alkyl and aryl
radicals at silicon.7 The trimethyltin group turned out to be
a highly efficient leaving group in these homolytic substi-
tutions (Scheme 1, equations 1 and 2).8 More recently, we
showed that acyl radicals undergo SHi reactions at silicon
to provide cyclic acyl silanes (Scheme 1, equation 3).9
Herein, we wish to report a new method for the stereocon-
trolled formation of cyclic vinyl silanes using the SHi re-
action of vinyl radicals at silicon.
1)
Li
R
OH
O
THF, –78 °C
Br
Br
2) H+/H2O
R
1
2 (63%, R = SiMe3)
3 (55%, R = Ph)
4 (36%, R = CH2SiMe3)
5 (35%, R = C(CH3)2OH)
Ph Ph
Si
O
SnMe3
ClSi(Ph)2SnMe3
NEt3, THF
Ph Ph
Br
Ph
2-5
Si
Ph
SnMe3
O
R
Si
O
R
(1)
+
SnMe3
R'
6 (84%, R = SiMe3)
7 (89%, R = Ph)
R'
R
8 (48%, R = CH2SiMe3)
9 (16%, R = C(CH3)2OH)
Ph
O
O
Si Ph
SnMe3
Ph
Si
Scheme 2 Preparation of the radical precursors
Ph
+
(2)
(3)
SnMe3
SnMe3
The first cyclization experiments were conducted using
bromide 6. Cylizations under typical atom transfer condi-
tions (Bu3SnSnBu3, 0.1 equivalent, benzene, hn)14 failed.
Pleasingly, addition of Bu3SnH (1 equivalent) and a,a¢-
azo-bis-isobutyronitrile (AIBN, 0.12 equivalent) in ben-
zene via syringe pump to bromide 6 in benzene (0.02 M)
over seven hours provided the desired cyclic vinyl silane
10 in 62% isolated yield (Scheme 3, Table 1, entry 1). The
product is formed via initial 5-exo-dig-cyclization of rad-
ical 14 to generate vinyl radical 15. SHi reaction at silicon
eventually afforded the cyclic alkoxysilane 10 and the tri-
methyl tin radical. Since a chain carrying tin radical is
formed during the cyclization (unimolecular chain trans-
Ph Ph
Si
Ph
Si
Ph
SnMe3
+
O
O
Scheme 1 SHi at silicon using alkyl, aryl and acyl radicals
SYNTHESIS 2004, No. 13, pp 2226–2235
Advanced online publication: 30.07.2004
DOI: 10.1055/s-2004-829186; Art ID: C04604SS
© Georg Thieme Verlag Stuttgart · New York
x
x.
x
x
.
2
0
0
4

SPECIAL TOPIC
Stereocontrolled Formation of Vinylsilanes
2227
fer process),8 the reaction should be conducted using sub- We next studied SHi reactions at Si leading to exocylic vi-
stoichiometric amounts of tin hydride. Therefore, the nyl silanes. To this end, iodo alcohols 16–19 were pre-
reaction was repeated using 0.5 equivalent of Bu3SnH un- pared from pent-4-yn-2-ol via HI addition (→ 16, 70%)15
der otherwise identical conditions. Indeed, all of the start- or radical I-transfer chemistry14 using ethyl iodoacetate
ing material was consumed and 10 was isolated in 84% (→ 17, 76%, cis:trans = 86:14), cyclohexyliodide (→ 18,
yield (entry 2). With 0.4 equivalent of tin hydride a slight- 26%, cis:trans = 84:16) or tert-butyliodide (→ 19, 30%,
ly lower yield was obtained (71%). In addition, 23% of cis:trans = 82:18). The cis/trans isomers of 18 and 19
unreacted starting material was identified (entry 3). The were readily separated by chromatography. Unfortunate-
same experiment using 36% AIBN afforded a similar re- ly, the two isomers of the I-transfer product 17 could not
sult (entry 4). The yield dropped to 25% if 0.2 equivalent be separated. Silylation as described above afforded the
of Bu3SnH was used. Along with 10 the starting material stannylated silyl ethers 20–23 (Scheme 4). Silyl ether 21
was recovered in 55% yield (entry 5). The following ex- was used as trans/cis mixture of isomers for the subse-
periments were conducted under the optimized conditions quent SHi reaction, whereas for 22 and 23 each isomer was
using 0.5 equivalent of tin hydride.
independently tested in the SHi reaction. Homolytic sub-
stitutions were performed under the optimized conditions.
The cyclic alkoxysilanes were difficult to isolate. There-
fore, the crude products were treated with an excess of
MeLi to provide the corresponding ring-opened vinyl si-
lanes 24–27 in moderate to good yields (Scheme 4). It is
known that alkyl substituted vinyl radicals are linear.16
Thus, for steric reasons cyclization of 28b leading to the
cis-double bond should be less favored as compared to the
cyclization via radical 28a. In fact, the size of the substit-
uent R influences the stereochemical outcome to a large
extent. Cyclization of 21 bearing a primary alkyl substitu-
ent cyclized with a 2:1 selectivity favoring the trans com-
pound (→ 25, 33%). A sharp increase of the selectivity
was observed upon switching to a system bearing a sec-
ondary R-substituent. Thus, SHi reaction of the cyclohexyl
derivative cis-22 provided after ring-opening vinyl silane
26 in 67% yield with high selectivity (trans:cis = 93:7).
An even better result was obtained for the tert-butyl com-
pound cis-23 where cyclization occurred with complete
stereocontrol (→ 27, 64%, only trans). The assignment of
the relative configuration is based on the stereospecific
protodesilylation of 27 using tetrabutylammoniumfluo-
ride (TBAF) to form 29. The cis double bond in 29 was
Transformation of the phenyl-substituted acetylene 7 pro-
vided vinyl silane 11 in 86% yield (entry 6). A lower yield
was obtained for the reaction using bromide 8. The de-
sired silane 12 was isolated in 43% yield (entry 7). A sim-
ilar yield was obtained for the reaction using 9 (→ 13,
47%, entry 8). In the reactions with 8 and 9, unreacted
starting material was recovered in 35% and 7%, respec-
tively.
Ph
O
Si Ph
Bu3SnH, AIBN
C6H6, D
6–9
R
10 (R = SiMe3)
11 (R = Ph)
12 (R = CH2SiMe3)
13 (R = C(CH3)2OH)
Ph Ph
Si
Ph Ph
Si
SnMe3
O
O
SnMe3
R
R
14
15
1
unambiguously assigned using H NMR spectroscopy.
The relative configuration for the other compounds was
assigned in analogy.
Scheme 3 5-exo-dig Cyclization with subsequent SHi at Si
Table 1 SHi Reaction at Silicon with Vinyl Radicals
Based on the mechanistic scheme it is obvious that the rel-
ative configuration of the starting vinyl iodide has no in-
fluence on the selectivity. Indeed, we showed that
cyclization of trans-22 and cis-22 occurs with the same
selectivity. Furthermore, as for the corresponding cis de-
rivative, SHi reaction of trans-23 provided only trans-27
in 57% yield. The cis isomer was not identified in the
crude 1H NMR spectrum.
Entry
Starting
material
Bu3SnH
(equiv)
Product
Yield [%]
1
2
3
4
5
6
7
8
6
6
6
6
6
7
8
9
1.0
0.5
0.4
0.4b
0.2
0.5
0.5
0.5
10
10
10
10
10
11
12
13
62
84
71a
78a
25a
86
Encouraged by the results obtained for 5-exo-type cy-
clizations we decided to study a system leading to a 6-
membered cyclic alkoxysilane. The desired vinyl iodide
32 was prepared starting from aldehyde 3017 via Wittig re-
action (→ 31, 51%),18 deprotection and subsequent silyla-
tion. SHi reaction using our standard protocol and MeLi
treatment afforded homoallylic alcohol 33 albeit in low
yield (16%, Scheme 5). Obviously, the SHi reaction is
slow and the unwanted direct reduction of the reactive vi-
43
47
a Yield determined by 1H NMR spectroscopy.
b 36% AIBN was used.
Synthesis 2004, No. 13, 2226–2235 © Thieme Stuttgart · New York

2228
A. Blum et al.
SPECIAL TOPIC
Ph
Si
nyl radical cannot completely be suppressed, even using
low tin hydride concentrations.
Ph
SnMe3
I
OH
I
ClSi(Ph)2SnMe3
NEt3, THF
O
In conclusion, we have shown that SHi reactions of vinyl
radicals at silicon leading to 5-membered cyclic alkoxysi-
lanes are efficient processes. These processes occur with
high stereocontrol providing a new entry into trisubstitut-
ed olefins. The cyclic alkoxysilanes and the correspond-
ing ring-opened vinylsilanes are useful building blocks in
organic synthesis. Stereospecific protodesilylation, bro-
mo- and iododesilylation are well established processes in
organic synthesis. Moreover, cyclic alkoxysilanes have
been shown by Denmark to be useful substrates for tran-
sition metal mediated C–C-bond forming reactions.19
Studies along this line are underway.
R
R
16 (R = H)
20 (64%, R = H)
17 (R = CH2CO2Et)
cis-18 (R = c-Hex)
trans-18 (R = c-Hex)
cis-19 (R = t-Bu)
21 (44%, R = CH2CO2Et)
cis-22 (71%, R = c-Hex)
trans-22 (88%, R = c-Hex)
cis-23 (70%, R = t-Bu)
trans-23 (60%, R = t-Bu)
trans-19 (R = t-Bu)
Ph
Ph
Si
Bu3SnH (0.5 equiv)
O
AIBN, C6H6
20-23
∆
R
MeLi
Ph
Ph
1H NMR and 13C NMR spectra were recorded on a Bruker DRX-
500, DRX-400, ARX-300 or ARX-200 spectrometer. IR spectra
were recorded on a Bruker IFS-200 or a Nicolet Magna-IR 750
spectrophotometer. Mass spectra were recorded as EI-MS on a
Varian CH7, as HRMS on a MAT 95S and as ESI-MS on a MAT
TSQ 700 or a Bruker MicroTof. Elemental analyses were per-
formed on a Heraeus CHN-Rapid analyzer. Solvents were purified
by standard methods. Air and moisture sensitive compounds were
handled under argon using Schlenk techniques.
OH Si
R
24 (26%, R = H)
25 (33%, R = CH2C(OH)Me2; trans:cis = 2:1)
26 (67%, R = c-Hex; trans:cis = 93:7)
27 (64%, R = t-Bu, trans:cis > 98:2)
Ph
Ph
OH
SnMe3
Ph
Ph
SnMe3
Si
O
Si
O
Preparation of the Propargylic Alcohols 2–5 (GP 1); General
Procedure
R
R
The alkyne was dissolved in THF and cooled to –78 °C (acetone/dry
ice). An equimolar amount of n-BuLi (1.52 M in hexane) was added
over 20 min. Stirring was continued for another 20 min, and a solu-
tion of 4-bromobutanal in a small amount of THF was carefully
added. After stirring at –78 °C for 2 h, sat. aq NH4Cl was added and
the mixture was allowed to warm to r.t. A small amount of H2O was
added, the organic layer was separated and the aqueous layer was
extracted twice with EtOAc. The organic phases were combined,
washed once with sat. aq NaCl and dried (MgSO4). After evapora-
tion of the solvent, the crude product was purified by flash chroma-
tography (FC) (SiO2).
28b
29
28a
Scheme 4 Stereoselective SHi reaction at Si
OTBDMS
OTBDMS
Wittig
I
O
31 (51%)
30
6-Bromo-1-(trimethylsilyl)hex-1-yn-3-ol (2)
Ph Ph
Si
According to GP 1 with ethynyl(trimethyl)silane (3.2 mL, 22.6
mmol), n-BuLi (1.52 M in hexane, 14.8 mL, 22.5 mmol) and 4-bro-
mobutanal (3.3 g, 21.9 mmol) in THF (52 mL). FC (MTBE–pen-
tane, 1:10) afforded 2 (3.54 g, 63%).
SnMe3
O
1) HF/pyridine
31
I
2) NEt3, THF
ClSi(Ph)2SnMe3
DMAP
IR (film): 3368, 2960, 2899, 2172, 1440, 1250, 1046, 843, 760, 700,
648, 563 cm–1.
32 (73%)
1H NMR (200 MHz, CDCl3): d = 4.38 (t, J = 6.3 Hz, 1 H, HCO),
3.43 (t, J = 6.5 Hz, 2 H, CH2Br), 2.30–1.70 (m, 5 H, CH2CH2, OH),
0.14 [s, 9 H, (CH3)3Si].
Ph Ph
Bu3SnH (0.5 equiv)
AIBN, C6H6
Si
O
32
13C NMR (50 MHz, CDCl3): d = 106.0 (C), 89.9 (C), 61.9 (CH),
35.9 (CH2), 33.3 (CH2), 28.3 (CH2), –0.2 (CH3).
∆
Anal. Calcd for C9H17BrOSi (249.22): C, 43.37; H, 6.88. Found: C,
43.01; H, 6.86.
MeLi
OH
SiPh2Me
6-Bromo-1-phenylhex-1-yn-3-ol (3)
According to GP 1 with phenylacetylene (2.8 mL, 25.5 mmol), n-
BuLi (1.52 M in hexane, 16.7 mL, 25.5 mmol) and 4-bromobutanal
(3.75 g, 24.5 mmol) in THF (56 mL). FC (MTBE–pentane, 1:5) af-
forded 3 (3.44 g, 55%).
33 (16%)
Scheme 5 SHi reaction at Si via a 6-exo-type cyclization
IR (film): 3363, 3057, 2959, 2870, 1753, 1598, 1489, 1442, 1335,
1041, 757, 691 cm–1.
Synthesis 2004, No. 13, 2226–2235 © Thieme Stuttgart · New York

SPECIAL TOPIC
Stereocontrolled Formation of Vinylsilanes
2229
1H NMR (300 MHz, CDCl3): d = 7.45–7.39 (m, 2 H, Harom), 7.35–
7.27 (m, 3 H, Harom), 4.65 (t, J = 6.1 Hz, 1 H, CHO), 3.50 (t, J = 6.6
Hz, 2 H, CH2Br), 2.17–2.07 (m, 2 H, CH2CH2), 1.99–1.92 (m, 2 H,
CH2CH2).
13C NMR (75 MHz, CDCl3): d = 131.7 (CH), 128.5 (CH), 128.3
(CH), 122.3 (C), 89.4 (C), 85.3 (C), 62.1 (CH), 36.2 (CH2), 33.3
(CH2), 28.5 (CH2).
MS (EI): m/z = 254/252 [M]+, 173 [M – Br]+, 153, 146, 131, 102,
75.
HRMS: m/z [M]+ calcd for C12H13BrO, 252.0149; found, 252.0134.
IR (film): 3067, 3049, 2961, 2911, 2171, 1333, 1250, 1105, 1072,
844, 762, 738, 699, 518, 494 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.55 (m, 4 H, Harom), 7.38 (m, 6 H,
Harom), 4.45 (t, J = 6.1 Hz, 1 H, HCO), 3.40 (t, J = 6.8 Hz, 2 H,
BrCH2), 2.02 (m, 2 H, CH2CH2), 1.89 (m, 2 H, CH2CH2), 0.22 [s, 9
H, (CH3)3Sn], 0.09 [s, 9 H, (CH3)3Si].
13C NMR (75 MHz, CDCl3): d = 137.2/137.1 (C), 134.5/134.6
(CH), 129.8/129.7 (CH), 128.0/127.9 (CH), 105.9 (C), 90.5 (C),
64.6 (CH), 36.8 (CH2), 33.5 (CH2), 28.5 (CH2), –0.2 (CH3), –10.1
(CH3).
MS (EI): m/z = peak pattern at 579 [M – Me]+, 431/429, 389/387,
7-Bromo-1-(trimethylsilyl)hept-2-yn-4-ol (4)
363/361, 279, 261, 197, 187, 135, 73 [TMS]+, 71, 59.
According to GP 1 with 1-(trimethylsilyl)-2-propyne (1.0 g, 8.9
mmol), n-BuLi (1.52 M in hexane, 5.6 mL, 8.9 mmol) and 4-bro-
mobutanal (1.28 g, 8.5 mmol) in THF (28 mL). FC (MTBE–pen-
tane, 5:1) afforded 4 (817 mg, 36%).
HRMS: m/z [M – CH3]+ calcd for C23H32BrOSi2Sn, 579.0190;
found, 579.0203.
1-(3-Bromopropyl)-3-phenyl-2-propynyldiphenyl(trimethyl-
stannyl)silyl Ether (7)
According to GP 2 with diphenyl(trimethylstannyl)silylchloride
(1.57 g, 4.2 mmol), 3 (1.14 g, 4.5 mmol) and NEt3 (0.68 mL,
4.9 mmol) in THF (16 mL). FC (MTBE–pentane, 1:100) afforded 7
(2.22 g, 89%).
IR (film): 3407, 2957, 2219, 1955, 1588, 1439, 1249, 1050, 849,
761, 698, 668, 561 cm–1.
1H NMR (300 MHz, CDCl3): d = 4.40 (td, J = 6.1, 2.2 Hz, 1 H,
HCO), 3.45 (t, J = 6.6 Hz, 2 H, CH2Br), 2.08–1.76 (m, 5 H,
CH2CH2, OH), 1.49 (d, J = 2.2 Hz, 2 H, CH2TMS), 0.10 [s, 9 H,
(CH3)3Si].
13C NMR (75 MHz, CDCl3): d = 84.1 (C), 79.5 (C), 62.1 (CH), 36.7
(CH2), 33.4 (CH2), 28.6 (CH2), 7.0 (CH2), -2.1 (CH3).
HRMS: m/z [M – H]+ calcd for C10H18BrOSi, 261.0310; found,
261.0306.
IR (film): 3066, 2963, 2912, 2224, 1956, 1489, 1442, 1428, 1336,
1105, 1069, 757, 739, 699, 520, 493 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.60–7.55 (m, 4 H, Harom), 7.40–
7.32 (m, 6 H, Harom), 7.29–7.20 (m, 5 H, Harom), 4.70 (t, J = 5.7 Hz,
1 H, HCO), 3.44 (t, J = 6.6 Hz, 2 H, CH2Br), 2.18–1.92 (m, 4 H,
CH2CH2), 0.19 [s, 9 H, (CH3)3Sn].
8-Bromo-2-methyloct-3-yne-2,5-diol (5)
13C NMR (75 MHz, CDCl3): d = 137.3 (C), 134.5/134.4 (CH),
131.7 (CH), 129.8/129.7 (CH), 128.4 (CH), 128.1 (CH), 128.1/
128.0 (CH), 122.5 (C), 89.6 (C), 86.1 (C), 64.6 (CH), 36.9 (CH2),
33.5 (CH2), 28.5 (CH2), –10.1 (CH3).
According to GP 1 with 2-methyl-3-butyn-2-ol (2.45 mL,
25.0 mmol), n-BuLi (1.52 M in hexane, 32.0 mL, 50 mmol) and 4-
bromobutanal (3.75 g, 24.8 mmol) in THF (56 mL). FC (MTBE–
pentane, 1:2) afforded 5 (2.06 g, 35%).
MS (EI): m/z = peak pattern at 583 [M – Me]+, 435/433 [M –
IR(film): 3340, 2980, 2933, 2873, 1630, 1441, 1364, 1242, 1163,
1048, 951, 668, 559 cm–1.
1H NMR (300 MHz, CDCl3): d = 4.44 (t, J = 6.1 Hz, 1 H, HCO),
3.46 (t, J = 6.8 Hz, 2 H, CH2Br), 2.08–1.98 (m, 2 H, CH2CH2),
1.88–180 (m, 2 H, CH2CH2), 1.75 (br s, 2 H, two OH), 1.51 [s, 6 H,
C(CH3)2].
SnMe3]+, 393/391, 363/361, 326, 283, 199/197, 155, 131, 71.
HRMS: m/z [M – CH3]+ calcd for C26H2881BrOSiSn, 583.0094;
found, 583.0110.
1-(3-Bromopropyl)-4-(trimethylsilyl)-2-butynyldiphenyl(tri-
methylstannyl)silyl Ether (8)
According to GP 2 with diphenyl(trimethylstannyl)silylchloride
(390 mg, 1.0 mmol), 4 (289 mg, 1.10 mmol) and NEt3 (0.17 mL,
1.2 mmol) in THF (5 mL). FC (MTBE–pentane, 1:100) afforded 8
(301 mg, 48%).
13C NMR (75 MHz, CDCl3): d = 89.9 (C), 82.5 (C), 65.1 (C), 61.3
(CH), 36.0 (CH2), 33.4 (CH2), 31.3 (CH3), 28.4 (CH2).
MS (EI): m/z = 221/219 [M – CH3]+, 203/201, 151/149, 113, 95, 79,
67, 59, 55, 43, 41.
HRMS: m/z [M – CH3 – H2]+ calcd for C8H1081BrO2, 218.9844;
found, 218.9860.
IR (film): 2962, 2906, 1428, 1261, 1102, 799, 699, 518, 491 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.57–7.51 (m, 4 H, Harom), 7.38–
7.33 (m, 6 H, Harom), 4.48 (t, J = 6.8 Hz, 1 H, HCO), 3.39 (t, J = 6.6
Hz, 2 H, CH2Br), 2.08–1.98 (m, 2 H, CH2CH2), 1.87–180 (m, 2 H,
CH2CH2), 1.39 (d, J = 2.2 Hz, 2 H, CH2TMS), 0.19 [s, 9 H,
(CH3)3Sn], 0.05 [s, 9 H, (CH3)3Si].
13C NMR (75 MHz, CDCl3): d = 137.6/137.5 (C), 134.5/134.4
(CH), 129.8/129.7 (CH), 128.0/127.9 (CH), 84.8 (C), 79.4 (C), 64.7
(CH), 37.5 (CH2), 33.6 (CH2), 28.6 (CH2), 7.3 (CH2), –2.0 (CH3),
–10.1 (CH3).
Silylation (GP 2); General Procedure
Diphenyl(trimethylstannyl)silylchloride was dissolved under argon
in THF and cooled to 0 °C. The alcohol and NEt3 or NEt3 and cata-
lytic amounts of DMAP were successively added. After stirring at
0 °C for 2 h the solvent was removed by evaporation. The residue
was suspended in pentane, filtered and washed several times with a
mixture of pentane–MTBE (1:1). The filtrate was collected and the
solvent removed by evaporation. The crude product was purified by
FC.
MS (EI): m/z = peak pattern at 593 [M – Me]+, 445/443 [M –
SnMe3]+, 363, 293, 135, 73 [TMS]+.
HRMS: m/z [M – CH3]+ calcd for C23H3481BrO120SnSi2, 595.0355;
found, 595.0349.
1-(3-Bromopropyl)-3-(trimethylsilyl)-2-propynyldiphenyl(tri-
methylstannyl)silyl Ether (6)
According to GP 2 with diphenyl(trimethylstannyl)silylchloride
(0.78 g, 2.0 mmol), 2 (0.58 g, 2.3 mmol) and NEt3 (0.34 mL,
2.4 mmol) in THF (8 mL). FC (MTBE–pentane, 1:100) afforded 6
(999 mg, 84%).
8-Bromo-5-{[diphenyl(trimethylstannyl)silyl]oxy}-2-methyl-
oct-3-yn-2-ol (9)
According to GP 2 with diphenyl(trimethylstannyl)silylchloride
(400 mg, 1.05 mmol), 5 (270 mg, 1.15 mmol), NEt3 (0.17 mL,
Synthesis 2004, No. 13, 2226–2235 © Thieme Stuttgart · New York

2230
A. Blum et al.
SPECIAL TOPIC
1.2 mmol) and DMAP (19 mg, 0.15 mmol) in THF (5 mL). FC
(MTBE–pentane, 1:10) afforded 9 (100 mg, 16%).
MS (EI): m/z = 354 [M]+, 326, 276, 249, 207, 199, 129, 104, 62, 54.
HRMS: m/z [M]+ calcd for C24H22OSi: 354.1440; found, 354.1441.
IR (film): 3397, 3048, 2959, 2919, 2866, 1893, 1646, 1428, 1357,
1340, 1154, 1119, 1102, 1053, 799, 740, 700, 568, 517, 484 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.60–7.50 (m, 4 H, Harom), 7.38
(m, 6 H, Harom), 4.50 (t, J = 6.0 Hz, 1 H, HCO), 3.42 (t, J = 6.6 Hz,
2 H, BrCH2), 2.03 (m, 2 H, CH2CH2), 1.90 (m, 2 H, CH2CH2), 1.31
[s, 6 H, C(CH3)2], 0.21 [s, 9 H, (CH3)3Sn].
13C NMR (75 MHz, CDCl3): d = 137,4 (C), 134.8/134.6 (CH),
129.9/129.8 (CH), 128.1/128,0 (CH), 90.5 (C), 82.3 (C), 64.3 (CH),
49.4 (C), 36.8, 33.4, 31.0 (CH3), 31.0 (CH3), 28.5, 27.0, –10.3
(CH3).
MS (EI): m/z = 417/415 [M – SnMe3]+, 399/397, 363/361, 294, 247,
199/197, 155, 139, 93.
HRMS: m/z [M – SnMe3]+ calcd for C21H2481BrO2Si, 417.0708;
found, 417.0692.
2,2-Diphenyl-3-[(trimethylsilyl)methyl]-4,5,6,6a-tetrahydro-
2H-cyclopenta[d][1,2]oxasilole (12)
According to GP 3 with 8 (105 mg, 172 mmol) in benzene (5 mL)
and a solution of Bu3SnH (23 mL, 86 mmol) and AIBN (3 mg,
18 mmol) in benzene (4 mL). FC (MTBE–pentane, 1:100) afforded
12 (27 mg, 43%).
IR (KBr): 3066, 2957, 2892, 1619, 1427, 1244, 1192, 1086, 859,
832, 737, 699, 577, 521, 487 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.63–7.60 (m, 4 H, Harom), 7.39–
7.30 (m, 6 H, Harom), 5.07 (dd, J = 10.5, 6.8 Hz, 1 H, HCO), 2.32–
2.28 (m, 1 H, CH2C=C), 2.18–2.08 (m, 1 H, CH2C=C), 1.94–1.68
(m, 2 H, CH2CH2CH2), 1.66 (s, 2 H, CH2TMS), 1.31–1.28 (m, 2 H,
CH2CHO), –0.25 [s, 9 H, (CH3)3Si].
13C NMR (75 MHz, CDCl3): d = 160.3 (C), 135.1/135.0 (CH),
134.5 (C), 130.1/131.0 (CH), 127.9/127.7 (CH), 126.6 (C), 86.5
(CH), 33.1 (CH2), 23.1 (CH2), 21.8 (CH2), 19.6 (CH2), –1.1 (CH3).
MS (EI): m/z = 364 [M]+, 349 [M – CH3]+, 336, 290, 277, 271, 199,
195, 193, 179, 135, 123.
HRMS: m/z [M]+ calcd for C22H28OSi2, 364.1679; found, 364.1685.
SHi Reaction (GP 3); General Procedure
The bromide was dissolved under argon in benzene and heated to
reflux. A solution of Bu3SnH and AIBN in benzene was added via
syringe pump during 7 h. After completed addition stirring was con-
tinued for 15 min. The mixture was allowed to cool to r.t. After
evaporation of the solvent the crude product was purified by FC.
2-(2,2-Diphenyl-4,5,6,6a-tetrahydro-2H-cyclopenta[d][1,2]ox-
asilol-3-yl)propan-2-ol (13)
According to GP 3 with 9 (91 mg, 157 mmol) in benzene (5 mL) and
a solution of Bu3SnH (21 mL, 76 mmol) and AIBN (3 mg, 18 mmol)
in benzene (4 mL). FC (MTBE–pentane, 1:10) afforded 13 (25 mg,
47%).
2,2-Diphenyl-3-(trimethylsilyl)-4,5,6,6a-tetrahydro-2H-cyclo-
penta[d][1,2]oxasilole (10)
According to GP 3 with 6 (121 mg, 0.20 mmol) in benzene (5 mL)
and a solution of Bu3SnH (27 mL, 0,10 mmol) and AIBN (4 mg,
24 mmol) in benzene (5 mL). FC (MTBE–pentane, 1:50) afforded
10 (60 mg, 84%).
IR (KBr): 3396, 3067, 2980, 2929, 1428, 1363, 1335, 1249, 1166,
1106, 1071, 997, 956, 771, 739, 699, 519, 493 cm–1.
IR (KBr): 3068, 2960, 1582, 1428, 1246, 1109, 1034, 987, 916, 894,
815, 699, 512 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.69–7.55 (m, 4 H, Harom), 7.46–
7.31 (m, 6 H, Harom), 4.92 (dd, J = 11.3, 7.0 Hz, 1 H, OCH), 2.52–
1.36 (m, 6 H, CH2CH2CH2), 0.01 [s, 9 H, (CH3)3Si].
13C NMR (50 MHz, CDCl3): d = 180.8 (C), 135.3/135.2 (CH),
139.1/130.0 (CH), 127.8/127.7 (CH), 126.5 (C), 88.5 (CH), 32.2
(CH2), 27.0 (C), 26.6 (CH2), 21.9 (CH2), 0.1 (CH3).
1H NMR (300 MHz, CDCl3): d = 7.79–7.66 (m, 4 H, Harom), 7.46–
7.34 (m, 6 H, Harom), 4.94 (dd, J = 11.2, 6.6 Hz, 1 H, HCO), 2.55–
2.33 (m, 2 H, CH2C=C), 2.26–2.18 (m, 1 H, CH2CH2CH2), 2.07–
1.81 (m, 2 H, CH2CHO), 1.58 (br s, 1 H, OH), 1.53–1.31 (m, 1 H,
CH2CH2CH2), 1.37 (s, 3 H, CH3), 1.27 (s, 3 H, CH3).
13C NMR (75 MHz, CDCl3): d = 160.1 (C), 138.9 (C), 135.9 (CH),
135.3 (C), 135.3 (C), 135.2 (CH), 130.1 (CH), 130.0 (CH), 127.9
(CH), 127.9 (CH), 86.9 (CH), 73.0 (C), 32.5 (CH2), 31.0 (CH3),
29.9 (CH3), 24.7 (CH2), 22.1 (CH2).
MS (EI): m/z = 350 [M]+, 277 [M – SiMe3]+, 200, 179, 139, 99, 75,
73 [SiMe3]+.
HRMS: m/z [M]+ calcd for C21H26OSi2, 350.1522; found, 350.1536.
MS (EI): m/z = 336 [M]+, 318, 308, 290, 277, 259, 243, 199, 182,
139, 120, 104, 62.
HRMS: m/z [M]+ calcd for C21H24O2Si, 336.1545; found, 336.1539.
Anal. Calcd for C21H26OSi2 (350.152): C, 71.94; H, 7.47. Found: C,
71.94; H, 7.58.
2,2,3-Triphenyl-4,5,6,6a-tetrahydro-2H-cyclopenta[d][1,2]oxa-
silole (11)
According to GP 3 with 7 (1.8 g, 3.0 mmol) in benzene (40 mL) and
a solution of Bu3SnH (0.41 mL, 1.5 mmol) and AIBN (0.06 g,
0,36 mmol) in benzene (40 mL). FC (MTBE–pentane, 1:50) afford-
ed 11 (920 mg, 86%).
4-Iodopent-4-en-2-ol (16)
NaI (4.3 g, 28.6 mmol) was dissolved in MeCN (25 mL). TMS-Cl
(2.76 mL, 28.6 mmol) and H2O (0.26 mL, 14.3 mmol) were succes-
sively added and the mixture was stirred for 10 min. Pent-4-yn-2-ol
(1.12 mL, 11.9 mmol) was added and the mixture stirred for 14 h at
r.t. After addition of H2O (50 mL), the resulting was mixture was
extracted 3 times with Et2O (20 mL). The combined organic phases
were washed with aq K2CO3 (5%, 20 mL), twice with aq Na2S2O3
(5%, 20 mL) and twice with H2O (20 mL). The organic layer was
dried with MgSO4. Removal of the solvent by evaporation afforded
16 (1.78 g, 70%). The product was used without further purifica-
tion.
IR (KBr): 3065, 2945, 2860, 1603, 1492, 1446, 1427, 1269, 1118,
1098, 1023, 978, 825, 770, 740, 698, 563, 520, 491 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.72–7.66 (m, 4 H, Harom), 7.55–
7.10 (m, 11 H, Harom), 5.13 (dd, J = 11.3, 6.7 Hz, 1 H, CHO), 2.85–
2.54 (m, 2 H, CH2–C=C), 2.39–2.27 (m, 1 H, CH2CH2), 2.16–2.03
(m, 2 H, CH2CH2), 1.68–1.46 (m, 1 H, CH2CH2).
13C NMR (75 MHz, CDCl3): 164.7 (C), 137.9 (C), 135.5 (CH),
135.3 (C), 134.8 (CH), 134.3 (C), 130.5 (CH), 130.2 (CH), 128.7
(C), 128.5 (CH), 128.4 (CH), 128.0 (CH), 128.0 (CH), 126.3 (CH),
87.0 (CH), 32.2 (CH2), 25.4 (CH2), 22.3 (CH2).
1H NMR (200 MHz, CDCl3): d = 6.17 (s, 1 H, Hvinyl), 5.85 (s, 1 H,
Hvinyl), 4.23–3.92 (m, 1 H, CHOH), 2.76–2.25 (m, 2 H, CHOHCH2),
1.58 (br s, 1 H, OH), 1.26 (d, J = 6.2 Hz, 3 H, CH3).
13C NMR (50 MHz, CDCl3): d = 123.6 (CH2), 102.6 (C), 65.8 (CH),
49.5 (CH2), 17.2 (CH3).
Synthesis 2004, No. 13, 2226–2235 © Thieme Stuttgart · New York

SPECIAL TOPIC
Stereocontrolled Formation of Vinylsilanes
2231
Atom Transfer Reactions (GP 4); General Procedure
Pent-4-yn-2-ol, iodoalkane and hexabutyldistannane were dis-
solved in benzene and irradiated for the given time in a sealed tube
with a 300 W sun lamp. The reaction mixture was cooled to r.t. and
the solvent was removed by evaporation. The crude product was pu-
rified by FC.
1H NMR (300 MHz, CDCl3): d = 5.44 (d, J = 8.3 Hz, 1 H, CICH),
4.18–3.97 (m, 1 H, CHOH), 2.56 (ddd, J = 13.8, 4.5, 1.0 Hz, 1 H,
CH2CI), 2.51 (ddd, J = 13.8, 8.2, 0.4 Hz, 1 H, CICH2), 2.38–2.10
(m, 1 H, ICCHCH), 1.82–0.95 (m, 11 H, HCyHex, OH), 1.21 (d,
J = 6.3 Hz, 3 H, CH3).
13C NMR (75 MHz, CDCl3): d = 142.8 (CH), 101.6 (C), 65.6 (CH),
54.6 (CH2), 45.7 (CH), 31.8, 28.3, 26.2, 25.9, 22.0 (CH3).
6-Hydroxy-4-iodohept-3-onic Acid Ethyl Ester (17)
According to GP 4 with pent-4-yn-2-ol (205 L, 2.5 mmol), iodoace-
tic acid ethyl ester (214 mg, 1.0 mmol) and Bu3SnSnBu3 (50 L,
0.1 mmol) in benzene (1.8 mL). Irradiation for 3 h and FC (pen-
tane–MTBE, 10:1, then 3:1) afforded 17 (227 mg, 76%, cis/
trans = 86:14).
MS (ESI): m/z = 317 [M + Na]+.
HRMS: m/z [M]+ calcd for C11H19InaO, 317.0373; found, 317.0381.
4-Iodo-6,6-dimethylhept-4-en-2-ol (19)
According to GP 4 with pent-4-yn-2-ol (210 mg, 2.5 mmol), t-bu-
tyliodide (455 mg, 2.5 mmol) and Bu3SnSnBu3 (250 L, 0.5 mmol)
in benzene (4.5 mL). Irradiation for 24 h and FC (pentane–MTBE,
5:1) afforded cis-19 (151 mg, 25%) and trans-19 (50 mg, 5%), (cis/
trans = 82:18).
IR (film): 3435, 2976, 2931, 1736, 1645, 1456, 1371, 1274, 1180,
1098, 1027, 940, 855, 792 cm–1.
cis-17
1H NMR (200 MHz, CDCl3): d = 5.91 (t, J = 6.5 Hz, 1 H, CICH),
4.20–3.97 (m, 1 H, CHOH), 4.14 (q, J = 7.1 Hz, 2 H, OCH2), 3.19
(d, J = 6.4 Hz, 2 H, CH2CO), 2.62 (d, J = 6.2 Hz, 2 H, CH2CI), 2.09
(d, J = 3.2 Hz, 1 H, OH), 1.26 (t, J = 7.4 Hz, 3 H, OCH2CH3), 1.23
(d, J = 6.2 Hz, 3 H, CHOHCH3).
cis-19
IR (film): 3375, 2961, 1616, 1461, 1364, 1255, 1119, 1085, 941,
656 cm–1.
1H NMR (300 MHz, CDCl3): d = 6.38 (s, 1 H, Hvinyl), 4.20–4.05 (m,
1 H, CHOH), 2.69 (dd, J = 14.6, 8.3 Hz, 1 H, CH2), 2.39 (dd,
J = 14.4, 4.1 Hz, 1 H, CH2), 1.76 (br s, 1 H, OH), 1.20 (d,
J = 6.3 Hz, 3 H, CHOHCH3), 1.09 [s, 9 H, C(CH3)3].
13C NMR (75 MHz, CDCl3): d = 154.6 (CH), 100.6 (C), 67.9 (CH),
48.8 (CH2), 37.5 (C), 31.3 (CH3), 22.2 (CH3).
13C NMR (75 MHz, CDCl3): d = 170.9 (C), 130.8 (CH), 108.6 (C),
66.4 (CH), 61.6 (CH2), 54.9 (CH2), 42.3 (CH2), 22.3 (CH3), 14.6
(CH3).
trans-17
1H NMR (200 MHz, CDCl3): d = 6.47 (t, J = 7.5 Hz, 1 H, CICH),
4.20–3.97 (m, 1 H, CHOH), 4.13 (q, J = 7.1 Hz, 2 H, OCH2), 2.62
(d, J = 7.9 Hz, 2 H, CH2CO), 2.42 (dd, J = 14.6, 3.6 Hz, 1 H,
CH2CI), 2.34 (dd, J = 13.2, 3.6 Hz, 1 H, CH2CI), 2.02 (s, 1 H, OH),
1.26 (t, J = 7.1 Hz, 3 H, OCH2CH3), 1.26 (d, J = 6.2 Hz, 3 H,
CHOHCH3).
MS (ESI): m/z = 291 [M + Na]+.
trans-19
IR (film): 3437, 2963, 1458, 1413, 1363, 1261, 1094, 1021, 865,
802 cm–1.
1H NMR (300 MHz, CDCl3): d = 5.98 (s, 1 H, Hvinyl), 4.20–4.00 (m,
1 H, CHOH), 2.57 (dd, J = 4.6, 3.6 Hz, 2 H, CH2), 1.55 (br s, 1 H,
OH), 1.15 (d, J = 6.3 Hz, 3 H, CHOHCH3), 1.13 [s, 9 H, C(CH3)3].
13C NMR (75 MHz, CDCl3): d = 147.3 (CH), 97.0 (C), 66.0 (CH),
57.6 (CH2), 33.7 (C), 29.9 (CH3), 21.8 (CH3).
13C NMR (75 MHz, CDCl3): d = 170.7 (C), 135.2 (CH), 102.1 (C),
66.8 (CH), 61.4 (CH2), 48.8 (CH2), 36.6 (CH2), 22.7 (CH3), 14.5
(CH3).
MS (EI): m/z = 298 [M]+, 254 [M – OEt]+, 225, 181, 127 [I]+, 99, 45.
HRMS: m/z [M]+ calcd for C9H15IO3, 298.0066; found, 298.0060.
MS (ESI): m/z = 291 [M + Na]+.
5-Cyclohexyl-4-iodopent-4-en-2-ol (18)
4-Iodo-2-(diphenyltrimethylstannylsilanoxy)-pent-4-ene (20)
According to GP 2 with diphenyl(trimethylstannyl)silyl-chloride
(1.00 g, 2.62 mmol), 16 (667 mg, 3.15 mmol) and Et3N (265 mg,
3.15 mmol) in THF (20 mL). FC (MTBE–pentane, 25:1) afforded
20 (773 mg, 61%).
According to GP 4 with pent-4-yn-2-ol (1.05 mL, 12.5 mmol), cy-
clohexyliodide (2.625 g, 12.5 mmol) and Bu3SnSnBu3 (250 L,
0.5 mmol) in benzene (9 mL). Irradiation for 62 h and FC (pentane–
MTBE, 5:1) afforded cis-18 (659 mg, 22%) and trans-18 (290 mg,
4%), (cis/trans = 84:16).
IR (film): 3086, 2972, 1428, 1125, 1087, 997, 739, 717, 700, 520,
493 cm–1.
cis-18
IR (film) : 3365, 2925, 2850, 1625, 1448, 1083, 937, 896, 638 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.60–7.48 (m, 4 H, Harom), 7.45–
7.31 (m, 6 H, Harom), 6.08 (d, J = 1.0 Hz, 1 H, Hvinyl), 5.71 (d,
J = 1.2 Hz, 1 H, Hvinyl), 4.26–4.13 (m, 1 H, CHOH), 2.69 (dd,
J = 16.5, 4.9 Hz, 1 H, CHOSiCH2), 2.45 (ddd, J = 14.2, 6.2, 1.1 Hz,
1 H, CHOSiCH2), 1.19 (d, J = 6.2 Hz, 3 H, CHOHCH3), 0.23 [s, 9
H, Sn(CH3)3].
1H NMR (300 MHz, CDCl3): d = 6.21 (d, J = 9.6 Hz, 1 H, CICH),
4.18–3.97 (m, 1 H, CHOH), 2.63 (ddd, J = 13.8, 8.2, 0.4 Hz, 1 H,
CH2CI), 2.40 (ddd, J = 14.0, 4.1, 0.7 Hz, 1 H, CICH2), 2.29 (qt,
J = 10.4, 3.5 Hz, 1 H, ICCHCH), 1.76–0.76 (m, 11 H, HCyHex, OH),
1.25 (d, J = 6.3 Hz, 3 H, CH3).
13C NMR (50 MHz, CDCl3): d = 137.9 (C), 134.6 (CH), 130.4
(CH), 129.8 (CH2), 128.1 (CH), 107.4 (C), 70.4 (CH), 54.7 (CH2),
22.9 (CH3), –10.0 (CH3).
13C NMR (75 MHz, CDCl3): d = 150.4 (CH), 97.0 (C), 66.8 (CH),
48.1 (CH2), 40.8 (CH), 33.0, 32.9, 26.0, 25.9, 16.7, 22.2 (CH3).
MS (ESI): m/z = 317 [M + Na]+.
HRMS: m/z [M]+ calcd for C11H19INaO, 317.0373; found,
MS (EI): m/z = 393 [M – SnMe3]+, 309 [ISiPh2SnMe3]+, 199, 197
[SiPh2Me]+, 195 [M – OSiPh2SnMe3]+, 181, 105, 77 [Ph]+, 41, 39.
317.0385.
HRMS: m/z [M – SnMe3]+ calcd for C17H18IOSi, 393.0172; found,
393.0188.
trans-18
IR (film): 3350, 2925, 2850, 1638, 1448, 1120, 1086, 965, 938, 893,
815, 620, 506 cm–1.
Synthesis 2004, No. 13, 2226–2235 © Thieme Stuttgart · New York

2232
A. Blum et al.
SPECIAL TOPIC
Ethyl 6-{[Diphenyl(trimethylstannyl)silyl]oxy}-4-iodohept-3-
enoate (21)
IR (film): 3440, 3069, 3049, 2967, 2926, 2851, 1626, 1448, 1428,
1126, 1102, 1078, 699, 520, 494 cm–1.
According to GP 2 with diphenyl(trimethylstannyl)silyl-chloride
(718 mg, 1.88 mmol), 17 (618 mg, 2.07 mmol) and Et3N (210 mg,
2.08 mmol) in THF (20 mL). FC (MTBE–pentane, 5:1) afforded 21
(532 mg, 44%, cis/trans: 80:20).
1H NMR (300 MHz, CDCl3): d = 7.60–7.47 (m, 4 H, Harom), 7.44–
7.30 (m, 6 H, Harom), 6.07 (d, J = 9.6 Hz, 1 H, CICH), 4.31–4.16 (m,
1 H, CHOH), 2.66 (ddd, J = 14.7, 6.1, 0.4 Hz, 1 H, CH2CI), 2.55
(dd, J = 14.1, 7.1 Hz, 1 H, CICH2), 2.29 (qt, J = 10.5, 3.5 Hz, 1 H,
ICCHCH), 1.75–0.73 (m, 11 H, HCyHex), 1.17 (d, J = 6.0 Hz, 3 H,
CHOHCH3), 0.24 [s, 9 H, Sn(CH3)3].
IR (film): 3451, 2975, 2927, 1736, 1427, 1371, 1274, 1178, 1127,
1102, 1050, 997, 771, 741, 718, 700, 524, 493 cm–1.
13C NMR (75 MHz, CDCl3): d = 150.5 (CH), 139.0, 138.7 (C),
135.5, 135.4 (CH), 130.6, (CH), 128.9 (CH), 97.3 (C), 70.9 (CH),
47.6 (CH2), 40.1 (CH), 32.0, 25.1, 25.0, 25.9, 21.9 (CH3), –11.3
(CH3).
cis-21
1H NMR (200 MHz, CDCl3): d = 7.81–7.27 (m, 10 H, Harom), 5.90
(t, J = 6.3 Hz, 1 H, CICH), 4.35–4.15 (m, 1 H, CHOSi), 4.15 (q,
J = 7.2 Hz, 2 H, OCH2), 3.07 (d, J = 6.8 Hz, 2 H, CH2CO), 2.82
(ddd, J = 14.0, 6.7, 0.9 Hz, 1 H, CH2CI), 2.61 (ddd, J = 14.0, 6.1,
0.9 Hz, 1 H, CH2CI), 1.26 (t, J = 7.1 Hz, 3 H, OCH2CH3), 1.19 (d,
J = 6.0 Hz, 3 H, CHOHCH3), 0.23 [s, 9 H, Sn(CH3)3].
+
MS (EI): m/z = 475 [M –SnMe3 ], 309 [ISiPh2]+, 249, 199, 197
[SiMePh2]+, 81, 55, 41.
cis-4-Iod-6,6-dimethyl-2-{[diphenyl(trimethylstannyl)si-
lyl]oxy}-hept-4-ene (cis-23)
According to GP 2 with diphenyl(trimethylstannyl)silyl-chloride
(742 mg, 2.14 mmol), cis-19 (521 mg, 1.95 mmol) and Et3N (217
mg, 2.14 mmol) in THF (20 mL). FC (MTBE–pentane–Et3N,
10:1:0.04) afforded cis-23 (838 mg, 70%).
13C NMR (75 MHz, CDCl3): d = 171.0 (C), 138.2 (C), 134.9 (CH),
130.3 (CH), 130.0, (CH), 128.4 (CH), 108.0 (C), 71.0 (CH), 61.3
(CH2), 54.9 (CH2), 42.3 (CH2), 22.1 (CH3), 14.6 (CH3), –9.8
(SnCH3).
trans-21
1H NMR (200 MHz, CDCl3): d = 7.81–7.27 (m, 10 H, Harom), 6.39
(t, J = 7.4 Hz, 1 H, CICH), 4.35–4.15 (m, 1 H, CHOSi), 4.11 (q,
J = 7.1 Hz, 2 H, OCH2), 2.62 (d, J = 7.9 Hz, 2 H, CH2CO), 2.74
(dd, J = 14.5, 7.3 Hz, 1 H, CH2CI), 2.48 (dd, J = 14.2, 5.6 Hz, 1 H,
CH2CI), 1.26 (t, J = 7.1 Hz, 3 H, OCH2CH3), 1.19 (d, J = 6.3 Hz, 3
H, CHOHCH3), 0.24 [s, 9 H, Sn(CH3)3].
Mp 40 °C.
IR (KBr): 3474, 3068, 3049, 2961, 2907, 2870, 2358, 1428, 1131,
1103, 1079, 987, 699, 519, 493 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.69–7.54 (m, 4 H, Harom), 7.46–
7.31 (m, 6 H, Harom), 6.35 (s, 1 H, CICH), 4.40–4.27 (m, 1 H,
CHOH), 2.61 (dd, J = 14.3, 6.6 Hz, 1 H, CH2), 2.41 (dd, J = 14.3,
6.3 Hz, 1 H, CH2), 1.04 (d, J = 5.0 Hz, 3 H, CHOHCH3), 0.94 [s, 9
H, C(CH3)3], 0.27 [s, 9 H, Sn(CH3)3].
13C NMR (75 MHz, CDCl3): d = 153.3 (CH), 138.0, 137.9 (C),
134.6 (CH), 129.8 (CH), 128.1, 128.0 (CH), 100.2 (C), 72.3 (CH),
48.6 (CH2), 37.3 (C), 31.3 (CH3), 22.9 (CH3), –10.0 (CH3).
13C NMR (75 MHz, CDCl3): d = 171.0 (C), 138.2 (C), 135.0 (CH),
134.7 (CH), 130.0, (CH), 128.4 (CH), 101.1 (C), 70.8 (CH), 61.3
(CH2), 48.9 (CH2), 36.6 (CH2), 23.3 (CH3), 14.5 (CH3), –9.8 (CH3).
MS (EI): m/z = peak pattern at 627 [M – Me]+, 593, 517, 439, 337,
227, 105, 78.
HRMS: m/z [M – Me]+ calcd for C23H30IO3SiSn, 626.9896; found,
626.9885.
MS (EI): m/z 449 [M – SnMe3]+, 353, 309 [ISiPh2]+, 249, 199, 197
[SiMePh2]+, 123, 57 [tBu]+.
HRMS: m/z [M – SnMe3]+ calcd for C21H26IOSi, 449.0798; found,
449.0795.
cis-5-Cyclohexyl-4-iodo-2-{[diphenyl(trimethylstannyl)si-
lyl]oxy}-pent-4-ene (cis-22)
According to GP 2 with diphenyl(trimethylstannyl)silyl–chloride
(454 mg, 1.19 mmol), cis-18 (368 mg, 1.25 mmol) and Et3N (127
mg, 1.25 mmol) in THF (15 mL). FC (MTBE–pentane–Et3N,
10:1:0.04) afforded cis-22 (673 mg, 88%).
trans-4-Iodo-6,6-dimethyl-2-{[diphenyl(trimethylstannyl)si-
lyl]oxy}-hept-4-ene (trans-23)
According to GP 2 with diphenyl(trimethylstannyl)silyl-chloride
(251 mg, 0.66 mmol), trans-19 (176 mg, 0.66 mmol) and Et3N (73
mg, 0.72 mmol) in THF (10 mL). FC (MTBE–pentane–Et3N,
10:1:0.04) afforded trans-23 (242 mg, 60%).
IR (film): 3469, 3067, 2969, 2924, 2850, 2359, 1428, 1126, 1103,
1070, 698, 518, 491 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.58–7.47 (m, 4 H, Harom), 7.41–
7.30 (m, 6 H, Harom), 5.39 (d, J = 8.3 Hz, 1 H, CICH), 4.31–3.19 (m,
1 H, CHOH), 2.78 (ddd, J = 13.7, 6.1, 0.8 Hz, 1 H, CH2CI), 2.52
(ddd, J = 14.4, 7.1, 0.5 Hz, 1 H, CICH2), 2.25–2.09 (m, 1 H, IC-
CHCH), 1.77–0.97 (m, 11 H, HCyHex), 1.15 (d, J = 6.0 Hz, 3 H,
CHOHCH3), 0.23 [s, 9 H, Sn(CH3)3].
13C NMR (75 MHz, CDCl3): d = 140.5 (CH), 136.4 (C), 133.3
(CH), 128.6 (CH), 125.9 (CH), 100.8 (C), 68.6 (CH), 54.7 (CH2),
44.5 (CH), 31.9, 25.2, 24.9, 21.9 (CH3), –9.7 (CH3).
IR (film): 3067, 2963, 2906, 1428, 1376, 1362, 1198, 1103, 1078,
770, 737, 699, 519, 493 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.61–7.48 (m, 4 H, Harom), 7.46–
7.30 (m, 6 H, Harom), 6.02 (s, 1 H, CH), 4.39–4.19 (m, 1 H, CHOH),
2.80 (dd, J = 13.9, 6.4 Hz, 1 H, CH2), 2.55 (dd, J = 13.8, 6.3 Hz, 1
H, CH2), 1.17 [s, 9 H, C(CH3)3)], 1.16 (d, J = 6.0 Hz, 3 H,
CHOHCH3), 0.24 [s, 9 H, Sn(CH3)3].
13C NMR (50 MHz, CDCl3): d = 146.1 (CH), 138.2, 137.9 (C),
134.6, 134.5 (CH), 129.8 (CH), 128.1 (CH), 97.3 (C), 70.5 (CH),
57.7 (CH2), 33.5 (C), 29.9 (CH3), 22.7 (CH3), –10.0 (CH3).
MS (EI): m/z = peak pattern at 599 [M – CH3]+, 449, 353, 309
[ISiPh2]+, 249 [M – OSiPh2SnMe3]+, 199, 197 [SiMePh2]+, 123, 57
[tBu]+.
HRMS(EI): m/z [M – Me]+ calcd for C23H32IOSiSn, 599.0289;
found, 599.0299.
MS (EI): m/z = 475 [M – SnMe3]+, 309 [ISiPh2]+, 249, 199, 197
[SiMePh2]+, 81, 55, 41.
trans-5-Cyclohexyl-4-iodo-2-{[diphenyl(trimethylstannyl)si-
lyl]oxy}-pent-4-ene (trans-22)
According to GP 2 with diphenyl(trimethylstannyl)silyl-chloride
(128 mg, 0.34 mmol), trans-18 (100 mg, 0.34 mmol) and Et3N (41
mg, 0.40 mmol) in THF (10 mL). FC (MTBE–pentane–Et3N,
10:1:0.04) afforded trans-22 (154 mg, 71%).
4-[Methyl(diphenyl)silyl]pent-4-en-2-ol (24)
According to GP 3 with 20 (210 mg, 377 mol) in benzene (18 mL)
and a solution of Bu3SnH (55 mg, 186 mmol) and AIBN (15 mg,
Synthesis 2004, No. 13, 2226–2235 © Thieme Stuttgart · New York

SPECIAL TOPIC
Stereocontrolled Formation of Vinylsilanes
2233
75 mmol) in benzene (1 mL). Treatment at 0 °C with MeLi (1.67 M
in Et2O, 2.36 mL), stirring overnight at r.t., aqueous workup and FC
(MTBE–pentane, 5:1) afforded 24 (28 mg, 26%).
IR (film): 3432, 3068, 2926, 2850, 1607, 1448, 1428, 1371, 1261,
1110, 789, 730, 700, 491, 433 cm–1.
trans-26
IR (film): 3404, 3068, 2963, 2924, 1486, 1428, 1373, 1253, 1111,
935, 791, 728, 700, 536, 486 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.58–7.45 (m, 4 H, Harom), 7.43–
7.30 (m, 6 H, Harom), 5.87 (d, J = 9.3 Hz, 1 H, SiCCHCH), 3.60–
3.46 (m, 1 H, CHOH), 2.61–2.46 (m, 1 H, SiCCHCH), 2.42 (ddd,
J = 13.6, 9.0, 0.2 Hz, 1 H, CH2CSi), 2.32 (ddd, J = 13.7, 4.3,
0.3 Hz, 1 H, SiCCH2), 1.77–0.96 (m, 11 H, HCyHex, OH), 1.06 (d,
J = 6.0 Hz, 3 H, CHOHCH3), 0.65 (s, 3 H, SiCH3).
13C NMR (75 MHz, CDCl3): d = 154.8 (CH), 136.7 (C), 135.2
(CH), 130.9 (C), 129.4, (CH), 128.0 (CH), 67.2 (CH), 40.2 (CH2),
38.1 (CH), 32.9, 27.1, 25.8, 22.9 (CH3), –3.1 (CH3).
1H NMR (200 MHz, CDCl3): d = 7.59–7.47 (m, 4 H, Harom), 7.45–
7.29 (m, 6 H, Harom), 5.97 (dt, J = 2.8, 1.4 Hz, 1 H, Hvinyl), 5.58 (dt,
J = 2.7, 0.6 Hz, 1 H, Hvinyl), 3.77–3.56 (m, 1 H, CHOH), 2.43 (ddd,
J = 13.9, 1.4, 0.6 Hz, 1 H, CHOHCH2), 2.28 (dddd, J = 14.6, 9.4,
1.2, 0.7 Hz, 1 H, CHOHCH2), 1.09 (d, J = 6.2 Hz, 3 H,
CHOHCH3), 0.69 (s, 3 H, SiCH3).
13C NMR (75 MHz, CDCl3): d = 145.9 (C), 135.7 (C), 135.1 (CH),
132.1 (CH2), 129.7, 129.6 (CH), 128.1 (CH), 66.1 (C), 46.8 (CH2),
23.0 (CH3), –3.7 (CH3).
MS (ESI): m/z = 387 [M + Na]+.
MS (ESI): m/z = 305 [M + Na]+.
cis-26
1H NMR (300 MHz, CDCl3): d = 7.58–7.45 (m, 4 H, Harom), 7.43–
7.30 (m, 6 H, Harom), 6.08 (d, J = 10.6 Hz, 1 H, SiCCHCH), 3.60–
3.46 (m, 1 H, CHOH), 2.30 (td, J = 4.6, 3.7 Hz, 1 H, CH2CSi), 2.08
(ddd, J = 13.1, 8.5, 0.2 Hz, 1 H, SiCCH2), 1.97 (qt, J = 10.9,
3.5 Hz, 1 H, SiCCHCH), 1.77–0.96 (m, 11 H, HCyHex, OH), 1.03 (d,
J = 6.0 Hz, 3 H, CHOHCH3), 0.69 (s, 3 H, SiCH3).
2-Methyl-5-[methyl(diphenyl)silyl]oct-4-ene-2,7-diol (25)
According to GP 3 with 21 (177 mg, 280 mol) in benzene (10 mL)
and a solution of Bu3SnH (40 mg, 140 mmol) and AIBN (11 mg,
50 mmol) in benzene (1 mL). Treatment at 0 °C with MeLi (1.67 M
in Et2O, 1.75 mL), stirring overnight at r.t., aqueous workup and FC
(pentane–EtOAc, 2:1) afforded trans-25 (19 mg, 20%) and cis-25
(12 mg, 13%), (trans/cis = 2:1).
13C NMR (75 MHz, CDCl3): d = 155.6 (CH), 137.2, 137.1 (C),
135.0, 134.9 (CH), 130.6 (C), 129.4, 129.3, (CH), 128.0, 127.9
(CH), 66.5 (CH), 41.6 (CH2), 38.1 (CH), 33.0, 32.5, 25.5, 22.5
(CH3), –3.1 (CH3).
trans-25
IR (film): 3384, 3068, 2964, 2926, 1609, 1456, 1428, 1379, 1260,
1109, 935, 793, 737, 721, 700, 515, 478 cm–1.
trans-6,6-Dimethyl-4-[methyl(diphenyl)silyl]hept-4-en-2-ol (27)
According to GP 3 with cis-23 (548 mg, 890 mol) in benzene (30
mL) and a solution of Bu3SnH (130 mg, 480 mmol) and AIBN (34
mg, 180 mmol) in benzene (1 mL). Treatment at 0 °C with MeLi
(1.67 M in Et2O, 5.3 mL), stirring overnight at r.t., aqueous workup
and FC (pentane–MTBE, 5:1) afforded 27 (192 mg, 64% trans
only).
1H NMR (300 MHz, CDCl3): d = 7.58–7.46 (m, 4 H, Harom), 7.43–
7.31 (m, 6 H, Harom), 6.15 (dd, J = 9.0, 6.3 Hz, 1 H, CSiCH), 3.65–
3.50 (m, 1 H, CHOH), 2.59 (ddd, J = 15.0, 14.7, 8.9 Hz, 2 H,
CH2CSi), 2.19 (dd, J = 9.0, 6.3 Hz, 2 H, CH2COH), 1.24 (s, 3 H,
HOCCH3), 1.21 (s, 3 H, OCCH3), 1.06 (d, J = 6.3 Hz, 3 H,
CHOHCH3), 0.67 (s, 3 H, SiCH3).
13C NMR (75 MHz, CDCl3): d = 143.2 (CH), 137.6 (C), 136.6 (C),
135.2 (CH), 129.5 (CH), 128.0 (CH), 71.1 (C), 67.2 (CH), 42.6
(CH2), 39.8 (CH2), 30.7, 30.0 (CH3), 23.6 (CH3), –3.2 (CH3).
According to GP 3 with trans-23 (102 mg, 166 mol) in benzene (8
mL) and a solution of Bu3SnH (24 mg, 82 mmol) and AIBN (6 mg,
40 mmol) in benzene (1 mL). Treatment at 0 °C with MeLi (1.67 M
in Et2O, 1.0 mL), stirring overnight at r.t., aqueous workup and FC
(pentane–MTBE, 5:1) afforded 27 (32 mg, 57% trans only).
MS (ESI): m/z = 377 [M + Na]+.
cis-25
IR (film): 3580, 3445, 3067, 2958, 2904, 1595, 1463, 1428, 1363,
1252, 1109, 1072, 1036, 939, 791, 730, 701, 516, 482 cm–1.
IR (film): 3339, 3068, 2967, 2927, 1612, 1456, 1428, 1376, 1260,
1110, 939, 907, 792, 726, 701, 482 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.60–7.46 (m, 4 H, Harom), 7.44–
7.28 (m, 6 H, Harom), 6.02 (s, 1 H, CSiCH), 3.75–3.51 (m, 1 H,
CHOH), 2.63 (ddd, J = 13.6, 9.1, 0.8 Hz, 1 H, CH2), 2.35 (ddd,
J = 13.8, 4.0, 1.3 Hz, 1 H, CH2), 1.37 (br s, 1 H, OH), 1.17 [s, 9 H,
C(CH3)3], 1.08 (d, J = 6.0 Hz, 3 H, CHOHCH3), 0.67 (s, 3 H,
SiCH3).
1H NMR (300 MHz, CDCl3): d = 7.58–7.50 (m, 4 H, Harom), 7.41–
7.32 (m, 6 H, Harom), 6.43 (t, J = 7.6 Hz, 1 H, CSiCH), 3.68–3.53
(m, 1 H, CHOH), 2.49 (dd, J = 13.1, 3.1 Hz, 1 H, CHOHCH2),
2.17–2.00 (m, 3 H), 1.09 (d, J = 6.1 Hz, 3 H, CHOHCH3), 1.00 (s,
3 H, HOCCH3), 0.95 (s, 3 H, OCCH3), 0.69 (s, 3 H, SiCH3).
13C NMR (75 MHz, CDCl3): d = 145.0 (CH), 137.1, 136.0 (two C),
135.1 (CH), 129.5 (CH), 128.2 (CH), 70.7 (C), 66.7 (CH), 49.1
(CH), 45.9 (CH2), 29.7, 29.0 (CH3), 22.8 (CH3), –1.6 (CH3).
13C NMR (50 MHz, CDCl3): d = 158.1 (CH), 137.2, 137.1 (C),
135.2, 135.0 (CH), 132.2 (C), 129.4, 129.3 (CH), 128.0, 127.9
(CH), 67.2 (CH), 39.7 (CH2), 35.9 (C), 31.6 (CH3), 23.1 (CH3), –2.8
(CH3).
MS (ESI): m/z = 377 [M + Na]+.
MS (ESI): m/z = 361 [M + Na]+.
HRMS: m/z [M + Na]+ calcd for C22H30NaOSi, 361.1964; found,
5-Cyclohexyl-4-[methyl(diphenyl)silyl]pent-4-en-2-ol (26)
According to GP 3 with cis-22 (479 mg, 750 mol) in benzene (10
mL) and a solution of Bu3SnH (109 mg, 370 mmol) and AIBN (29
mg, 150 mmol) in benzene (1 mL). Treatment at 0 °C with MeLi
(1.67 M in Et2O, 4.4 mL), stirring overnight at r.t., aqueous workup
and FC (pentane–MTBE, 5:1) afforded trans-26 (143 mg, 53%) and
a cis/trans mixture (39 mg, 14%, 56:44), (trans/cis = 93:7).
361.1967.
6,6-Dimethylhept-4-en-2-ol (29)
A solution of 27 (59 mg, 170 mol) in THF (1 mL) was treated with
TBAF (1 M in THF, 0.87 mL). After stirring for 14 h at r.t. no reac-
tion could be observed via TLC. The mixture was heated in a sealed
tube and stirred for 8 h at 70 °C. After cooling to r.t., H2O (2 mL)
was added and the aqueous layer was extracted 3 times with Et2O.
The combined organic phases were dried with MgSO4 and the sol-
vent was removed by evaporation. Purification of the crude product
by FC (pentane–MTBE, 5:1) afforded 29 (11 mg, 45%).
According to GP 3 with trans-22 (11 mg, 18 mol) in benzene (1 mL)
and a solution of Bu3SnH (3 mg, 10 mmol) and AIBN (1 mg,
5 mmol) in benzene (1 mL). Treatment at 0 °C with MeLi (1.67 M
in Et2O, 0.12 mL), stirring overnight at r.t. and aqueous workup af-
forded the crude product mixture of 26 (cis/trans = 93:7).
Synthesis 2004, No. 13, 2226–2235 © Thieme Stuttgart · New York

2234
A. Blum et al.
SPECIAL TOPIC
IR (film): 3445, 2957, 2924, 2854, 1739, 1462, 1377, 1261, 1112,
802, 700, 617, 522 cm–1.
IR (film): 3346, 2966, 2912, 1651, 1425, 1374, 1127, 1110, 1044,
938, 849, 580 cm–1.
1H NMR (200 MHz, CDCl3): d = 5.53 [dt, J = 9.1, 0.8 Hz, 1 H,
CHC(CH3)3], 5.19 (ddd, J = 12.1, 8.0, 7.0 Hz, 1 H, CH2CHCH),
3.92–3.73 (m, 1 H, CHOH), 2.63 (ddd, J = 14.5 7.8, 1.5 Hz, 1 H,
CH2), 2.35 (ddd, J = 12.3, 5.3, 1.7 Hz, 1 H, CH2), 1.58 (br s, 1 H,
OH), 1.22 (d, J = 6.2 Hz, 3 H, CHOHCH3), 1.11 [s, 9 H, C(CH3)3].
13C NMR (75 MHz, CDCl3): d = 142.8 (CH), 123.9 (CH), 68.3
(CH), 38.3 (CH2), 35.6 (C), 31.5 (CH3), 23.2 (CH3).
1H NMR (200 MHz, CDCl3): d = 5.47 (td, J = 6.8, 1.5 Hz, 1 H,
CH), 4.01–3.76 (m, 1 H, CHOH), 2.47 (q, J = 1.3 Hz, 3 H, CICH3),
2.21 (tq, J = 6.4, 1.1 Hz, 2 H, CH2), 1.16 (d, J = 6.0 Hz, 3 H,
H3CCHO).
13C NMR (50 MHz, CDCl3): d = 131.7 (CH), 103.5 (C), 67.2 (CH),
46.1 (CH2), 33.9 (CH3), 23.2 (CH3).
MS (ESI): m/z = 249 [M + Na]+.
According to GP 2 with diphenyl(trimethylstannyl)silyl-chloride
(251 mg, 660 mmol), 5-iodohex-4-ene-2-ol (150 mg, 666 mmol)
and Et3N (101 mg, 1.0 mmol) in THF (15 mL). FC (MTBE–pen-
tane–Et3N, 10:1:0.04) afforded 32 (278 mg, 73%).
3-{[tert-Butyl(dimethyl)silyl]oxy}butyraldehyde (30)
3-{[tert-Butyl(dimethyl)silyl]oxy}butyric acid ethyl ester (1.0 g,
4.03 mmol) was dissolved in toluene (14 mL) and cooled to –78 °C.
DIBALH (1 M in THF, 4.07 mL, 4.07 mmol) was added. After stir-
ring at –78 °C for 10 min sat. NH4Cl solution (1.4 mL) was added.
The mixture was allowed to warm to r.t. and stirred for 1 h. Et2O
(30 mL) was added, and after stirring for 1 h the solution was dried
with MgSO4. Removal of the solvent by evaporation afforded 30
(803 mg, 98%). The product was used without further purification.
1H NMR (200 MHz, CDCl3): d = 9.74 (t, J = 2.5 Hz, 1 H, CHO),
4.29 (m, J = 5.9 Hz, 1 H, CHOSi), 2.46 (dd, J = 7.0, 2.8 Hz, 1 H,
CH2), 2.43 (dd, J = 5.4, 1.9 Hz, 1 H, CH2), 1.18 (d, J = 6.0 Hz, 3 H,
CHCH3), 0.81 [s, 9 H, C(CH3)3], 0.03 (s, 3 H, SiCH3), 0.02 (s, 3 H,
SiCH3).
IR (film): 3444, 3067, 2965, 2910, 2358, 1650, 1427, 1105, 1051,
1004, 793, 699, 518, 492 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.58–7.49 (m, 4 H, Harom), 7.44–
7.32 (m, 6 H, Harom), 5.45 (tq, J = 6.6, 1.2 Hz, 1 H, CICH), 4.10–
3.98 (m, 1 H, CHOH), 2.45 (d, J = 1.3 Hz, 3 H, CICH3), 2.42–2.12
(m, 2 H, CH2), 1.22 (d, J = 6.0 Hz, 3 H, H3CCHOH), 0.30 [s, 9 H,
Sn(CH3)3].
13C NMR (75 MHz, CDCl3): d = 138.0 (C), 134.6, 134.5 (CH),
132.2, 129.8 (two CH), 128.2 (CH), 102.9 (C), 70.7 (CH), 46.4
(CH2), 33.9 (CH3), 23.5 (CH3), –10.2 (CH3).
MS (EI): m/z = 407 [M – SnMe3]+, 309 [ISiPh2]+, 235, 197
tert-Butyl-[(4-iodo-1-methylpent-3-en-1-yl)oxy]dimethylsilane
(31)
[SiPh2Me]+, 105, 81.
Ethylphosphoniumbromide (2 g, 5.39 mmol) was suspended in
THF (50 mL) and treated with n-BuLi (1.5 M, in hexane, 3.6 mL,
5.39 mmol). The ylid was transferred by cannula to a cold (–78 °C)
solution of I2 (1.367 g, 5.39 mmol) in THF (100 mL). The suspen-
sion was stirred for 10 min and warmed to –20 °C. NaHMDS (1 M
in THF, 4.8 mL) was added and the mixture was stirred for another
10 min at –20 °C. The solution was cooled to –78 °C and aldehyde
30 (544 mg, 2.69 mmol) in THF (20 mL) was added. After stirring
for 10 min at –78 °C the mixture was allowed to warm to r.t. and
stirred for 62 h. The solvent was removed by evaporation. The res-
idue was suspended in a mixture of pentane–MTBE (10:1) and fil-
tered through a plug of silica. The filtrate was collected and the
solvent removed by evaporation. Purification of the crude product
by FC (pentane–MTBE, 10:1) afforded 31 (466 mg, 51%).
HRMS: m/z [M – SnMe3]+ calcd C18H20IOSi, 407.0328; found,
407.0317.
5-[Methyl(diphenyl)silyl]hex-4-en-2-ol (33)
According to GP 3 with 32 (172 mg, 300 mmol) in benzene (15 mL)
and a solution of Bu3SnH (43 mg, 150 mmol) and AIBN (11 mg,
60 mmol) in benzene (1 mL). Treatment at 0 °C with MeLi (1.67 M
in Et2O, 1.8 mL), stirring overnight at r.t., aqueous workup and FC
(MTBE–pentane, 5:1) afforded 33 (14 mg, 16%).
IR (film): 3364, 3068, 2966, 2927, 1617, 1428, 1373, 1253, 1111,
1080, 1046, 939, 791, 722, 700, 528, 494 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.57–7.47 (m, 4 H, Harom), 7.41–
7.31 (m, 6 H, Harom), 6.31 (tq, J = 7.5, 1.6 Hz, 1 H, CSiCH), 3.63–
3.48 (m, 1 H, CHOH), 2.04 (dq, J = 6.3, 1.3 Hz, 1 H, CH2), 2.00
(dq, J = 6.3, 1.3 Hz, 1 H, CH2), 1.85 (q, J = 1.4 Hz, 3 H, SiCCH3),
0.94 (d, J = 6.3 Hz, 3 H, H3CCHOH), 0.63 (s, 3 H, SiCH3).
13C NMR (75 MHz, CDCl3): d = 141.5 (CH), 137.0 (C), 135.0
(CH), 134.4 (C), 129.4 (CH), 128.1 (CH), 68.1 (CH), 42.0 (CH2),
26.1 (CH3), 22.9 (CH3), –2.0 (CH3).
IR (film): 2956, 2929, 2856, 1652, 1472, 1427, 1376, 1255, 1132,
1094, 1061, 1002, 836, 775 cm–1.
1H NMR (200 MHz, CDCl3): d = 5.47 (td, J = 5.2, 1.6 Hz, 1 H,
CICH), 3.90–3.72 (m, 1 H, CHOSi), 2.48 (t, J = 1.2 Hz, 3 H,
CICH3), 2.19 (t, J = 6.8 Hz, 2 H, CH2), 1.11 (d, J = 6.2 Hz, 3 H,
H3CCHOSi), 0.83 [s, 9 H, C(CH3)3], 0.00 (s, 6 H, SiCH3).
13C NMR (50 MHz, CDCl3): d = 131.7 (CH), 101.7 (C), 68.1 (CH),
47.3 (CH2), 34.9 (CH3), 27.2 (CH3), 25.0 (CH3), 20.1 (C), –2.4
(CH3), –2.6 (CH3).
MS (ESI): m/z = 319 [M + Na]+.
HRMS: m/z [M + Na]+ Calcd for C19H24NaOSi: 319.1489. Found:
319.1486.
MS (EI): m/z = 283 [M – tBu]+, 185 [ISiMe2]+, 159, 155, 81, 73, 32.
HRMS: m/z [M – tBu]+ calcd C8H16IOSi, 283.0015; found,
283.0031.
Acknowledgment
We thank the Fonds der Chemischen Industrie for continuous sup-
port. We thank Heinrich Luftmann und Birgit Janza for their help
during the preparation of the manuscript.
5-Iodo-2-{[diphenyl(trimethylstannyl)silyl]oxy}hex-4-ene (32)
A solution of silyl ether 31 (298 mg, 0.87 mmol) in CH2Cl2 (20 mL)
was cooled to 0 °C. HF·pyridine (0.31 mL, 12.1 mmol) was added
and the solution was allowed to warm to r.t. After stirring for 14 h
sat. aq Na2CO3 (20 mL) was added. The aqueous phase was sepa-
rated and extracted 5 times with Et2O (5 mL) the organic phases
were combined and dried with MgSO4. The solvent was removed by
evaporation. Purification of the crude product by FC (pentane–
MTBE, 5:1) afforded 5-iodohex-4-en-2-ol (121 mg, 62%).
References
(1) New address: Organisch-Chemisches Institut, Westfälische
Wilhelms-Universität, Corrensstraße 40, 48149 Münster,
Germany.
Synthesis 2004, No. 13, 2226–2235 © Thieme Stuttgart · New York

SPECIAL TOPIC
Stereocontrolled Formation of Vinylsilanes
2235
(2) (a) Davis, D. D.; Ahmed, F. U. J. Am. Chem. Soc. 1981, 103,
7653. (b) Ashcroft, M. R.; Bury, A.; Cooksey, C. J.; Davies,
A. G.; Gupta, B. D.; Johnson, M. D.; Morris, H. J.
(9) (a) Studer, A.; Amrein, S.; Matsubara, H.; Schiesser, C. H.;
Doi, T.; Kawamura, T.; Fukuyama, T.; Ryu, I. Chem.
Commun. 2003, 1190. (b) See also: Matsubara, H.;
Schiesser, C. H. Org. Biomol. Chem. 2003, 1, 4335.
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