Carbosilylation of allenes catalyzed by palladium complexes: A new efficient route to substituted allylic silanes

Article abstract of DOI:10.1021/jo982307a

An aromatic or olefinic halide RX (C₆H₅I, p-CH₃COC₆H₄I, p- NO₂C₆H₄I, p-CH₃OC₆H₄I, o-CH₃OC₆H₄I, m-C

Full text of DOI:10.1021/jo982307a

J . Org. Chem. 1999, 64, 2471-2474
2471
Ca r bosilyla tion of Allen es Ca ta lyzed by P a lla d iu m Com p lexes: A
New Efficien t Rou te to Su bstitu ted Allylic Sila n es
Ming-Yuan Wu, Feng-Yu Yang, and Chien-Hong Cheng*
Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan, 30043
Received November 23, 1998
An aromatic or olefinic halide RX (C6H5I, p-CH3COC6H4I, p-NO2C6H4I, p-CH3OC6H4I, o-CH3OC6H4I,
m-C2H5OCOC6H4I, (Z)-C2H5OCOCHdCHI, 3-iodocyclopent-2-en-1-one, 1-iodothiophene, 1-iodonaph-
thalene, 3-bromo-5,5-dimethylcyclohex-2-en-1-one, or R-bromostyrene), Bu3SnSiMe3 (2), and 1,1-
dimethylallene (3a ) undergo three-component coupling reaction in toluene in the presence of Pd(dba)2
(dba ) dibenzylideneacetone) to give an allylic silane (Me)2CdC(R)CH2SiMe3 in good to excellent
yields. When X ) I, the yields are substantially higher than when X ) Br or Cl (no reaction). This
carbosilylation reaction is highly regioselective, with the R group adding to the middle carbon and
the silyl group to the unsubstituted terminal carbon of 3a . Monosubstituted allenes R′′CHdCd
CH2 (R′′ ) cyclo-C6H11, n-Bu, and Ph) also undergo carbosilylation with PhI and 2, producing R′′CHd
C(Ph)CH2SiMe3 stereoselectively with Z/E between 98/2 and 80/20. Bulkier organic halides and
allenes give products with higher Z/E ratios. Based on known palladium-allene and -allyl
chemistry, we propose a mechanism to account for this palladium-catalyzed three-component
coupling reaction.
Sch em e 1
In tr od u ction
An efficient metal-catalyzed addition of an electrophile
(E) and a nucleophile (N) to a carbon-carbon double bond
(Scheme 1) is greatly beneficial to organic synthesis. In
the reaction, three organic units are assembled to give a
product consisting of two new chemical bonds.1 Techni-
cally, to achieve this three-component coupling reaction,
it is necessary to suppress competitive reactions such as
direct coupling of the electrophile and nucleophile, â-hy-
dride elimination, and polymerization of the alkene.2
Increasing effort in this area has led to the development
of new synthetic methods. Tsuji and co-workers reported
a palladium-promoted decarbonylative coupling of acid
chlorides, disilanes, and 1,3-dienes to give allylic silanes
(eq 1),3 whereas Murai et al. presented an addition of
trimethylsilyl and alkynyl units to acetylenes.4
to â-hydride elimination.5 In this paper, we report a new
method for the synthesis of allylic silanes by palladium-
catalyzed three-component coupling of organic halides,
allenes, and organosilylstannanes (eq 2). This catalytic
carbosilylation involves activation of C-X6 and Si-Sn7
bonds and regioselective addition of an organic and silyl
groups to allenes. Allylic silanes are useful reagents in
organic synthesis.8,9 The present palladium-catalyzed
reaction provides a convenient and extremely efficient
new route for the synthesis of a wide range of highly
substituted allylic silanes which are obtained only with
difficulty according to previous methods.3,10
(5) (a) Besson, L.; Gore, J .; Cazes, B. Tetrahedron Lett. 1995, 36,
3853-3856. (b) Anie`s, C.; Cazes, B.; Gore´, J . J . Chem. Res. (S) 1996,
116-117. (c) Vicart, N.; Cazes, B.; Gore, J . Tetrahedron 1996, 52,
9101-9110. (d) Yamamoto, Y.; Al-Masum, M.; Asao, N. J . Am. Chem.
Soc. 1994, 116, 6019-6020. (e) Larock, R. C.; Tu, C.; Pace, P. J . Org.
Chem. 1998, 63, 6859-6866. (f) Larock, R. C.; He, Y.; Leong, W. W.;
Han, X.; Refvik, M. D.; Zenner, J . M. J . Org. Chem. 1998, 63, 2154-
2160.
Allene appears to be an excellent candidate as an
unsaturated organic substrate in the three-component
coupling because it inserts rapidly into a metal-carbon
bond and the resulting π-allyl species is relatively stable
(6) Heck, R. F. Acc. Chem. Res. 1979, 12, 146-151.
(7) (a) Obora, Y.; Tsuji, Y.; Asayama, M.; Kawamura, T. Organo-
metallics 1993, 12, 4697-4699. (b) Murakami, M.; Morita, Y.; Ito, Y.
J . Chem. Soc., Chem. Commun. 1990, 428-429. (c) Mitchell, T. N.;
Wickenkamp, R.; Amamria, A.; Dicke, R.; Schneider, U. J . Org. Chem.
1987, 52, 4868-4874. (d) Chenard, B. L.; Van Zyl, C. M. J . Org. Chem.
1986, 51, 3561-3566.
(1) (a) Chatani, N.; Amishiro, N.; Morii, T.; Yamashita, T.; Murai,
S. J . Org. Chem. 1995, 60, 1834-1840. (b) Ikeda, S. I.; Sato, Y. J . Am.
Chem. Soc. 1994, 116, 5975-5976. (c) Ryu, I.; Yamazaki, H.; Kusano,
K.; Ogawa, A.; Sonoda, N. J . Am. Chem. Soc. 1991, 113, 8558-8560.
(d) Suzuki, M.; Yanagisawa, A.; Noyori, R. J . Am. Chem. Soc. 1988,
110, 4718-4726.
(8) (a) Koreeda, M.; Ciufolini, M. A. J . Am. Chem. Soc. 1982, 104,
2308-2310. (b) Fleming, I.; Pulido, F. J . J . Chem. Soc., Chem.
Commun. 1986, 1010-1011.
(9) (a) Hosomi, A. Acc. Chem. Res. 1988, 21, 200-206. (b) Chan, T.
H.; Fleming, I. Synthesis 1979, 761-786.
(10) (a) Ojima, I.; Kumagai, M.; Miyazawa, Y. Tetrahedron Lett.
1977, 1385-1388. (b) Matsumoto, H.; Yako, T.; Nagashima, S.; Motegi,
T.; Nagai, Y. J . Organomet. Chem. 1978, 148, 97-106. (c) Tsuji, Y.;
Kajita, S.; Isobe, S.; Funato, M. J . Org. Chem. 1993, 58, 3607-3608.
(d) Gilman, H.; Zuech, E. A. J . Am. Chem. Soc. 1959, 81, 5925-5928.
(e) Seyferth, D.; Wursthorn, K. R.; Mammarella, R. E. J . Org. Chem.
1977, 42, 3104-3106.
(2) (a) Shimizu, I.; Sugiura, T.; Tsuji, J . J . Org. Chem. 1985, 50,
537-539. (b) Negishi, E.; Noda, Y.; Lamaty, F.; Vawter, E. J .
Tetrahedron Lett. 1990, 31, 4393-4396.
(3) (a) Obora, Y.; Tsuji, Y.; Kawamura, T. J . Am. Chem. Soc. 1995,
117, 9814-9821. (b) Obora, Y.; Tsuji, Y.; Kawamura, T. J . Am. Chem.
Soc. 1993, 115, 10414-10415.
(4) Chatani, N.; Amishiro, N.; Murai, S. J . Am. Chem. Soc. 1991,
113, 7778-7780.
10.1021/jo982307a CCC: $18.00 © 1999 American Chemical Society
Published on Web 03/05/1999

2472 J . Org. Chem., Vol. 64, No. 7, 1999
Wu et al.
Ta ble 1. P a lla d iu m -Ca ta lyzed Ca r bosilyla tion of
Allen esa
Resu lts a n d Discu ssion
Treatment of iodobenzene (1a ) and Bu3SnSiMe3 (2)
with 1,1-dimethylallene (3a ) in the presence of Pd(dba)2
(5%) (dba ) dibenzylideneacetone) in toluene at 80 °C
led to isolation of allylic silane 4a in excellent yield. The
reaction is highly regioselective with the phenyl group
adding to the middle carbon and the silyl group to the
nonsubstituted terminal carbon of 3a . No product that
consists of a stannyl group attached to the allene was
detected from the reaction. Under similar conditions,
many substituted aryl iodides also undergo three-
component coupling with 2 and 3a (Table 1). Aryl iodides
with either an electron-donating or -withdrawing func-
tionality at the ortho, meta, or para position all appear
to react smoothly to afford the corresponding allylic
silanes in high yields (entries 1-6). Like 1a , bromo-
benzene reacts with 2 and 3a to afford 4a , but in lower
yield (12% yield). In contrast, chlorobenzene shows
essentially no reaction with 2 and 3a in the presence of
Pd(dba)2.
Several types of organic halides also react with 2 and
3a to afford the corresponding allylic silanes in high
yields. Thus, 2-iodothiophene gave the corresponding
addition product in 85% yield. Alkenyl halides, 3-iodo-
cyclopent-2-en-1-one (1h ), ethyl (Z)-3-iodoacrylate (1i),
3-bromo-5,5-dimethylcyclohex-2-en-1-one (1j), and a-bro-
mostyrene (1k ) gave the corresponding allylic silanes in
61-83% yields (entries 8-11). In product 4i, the cis
stereochemistry of the acrylate group is faithfully trans-
ferred from the original (Z)-3-iodoacrylate.
In addition to 3a , monosubstituted allenes 3b, 3c, and
3d also undergo three-component carbosilylation with
PhI and 2, producing allylic silanes regio- and stereo-
selectively in 80-91% yields. The stereoselectivity of
these products depends greatly on the organic halide and
the substituent on the allene. Bulkier organic halides and
allenes give products with higher Z/E ratios. Thus,
R-iodonaphthalene and 1-cyclohexylallene using Pd(dba)2
as catalyst afforded product 4l in a Z/E ratio of 98/2.
Other aryl iodides and allenes gave allylic silanes with
Z/E ratios between 92/8 and 80/20. The stereochemistry
of these silane products was determined using typical 1H
NMR NOE technique. For example, there are two iso-
mers 4n and 4n ′ isolated from carbosilylation of 3b with
1b and 2. The minor product 4n ′ exhibits 1H NMR signals
at 1.82 and 5.15 ppm for the methylene (Hc) and olefin
a
Reaction conditions: RX (1: 1.00 mmol), Bu3SnSiMe3 (2: 1.00
mmol), allene (3: 2.00 mmol), Pd(dba)2 (0.0500 mmol, 5 mol %),
and toluene (3.0 mL) at 80 °C for 7 h. Isolated yields. c Yields in
b
parentheses were determined by NMR.
proton (Hd), respectively. Irradiation at the Hc signal
led to increase of the intensity of Hd by 5.75%. Similarly,
irradiation at the Hd signal resulted in increase of the
intensity of Hc by 4.82%. In contrast, irradiation at the
methylene (Ha) and at the olefin (Hb) proton signals of
4n showed essentially no change of the intensity of Hb
and Ha signals, respectively. These NOE results clearly
show that the major product 4n is a Z isomer, while 4n ′
is an E product.

Substituted Allylic Silanes
J . Org. Chem., Vol. 64, No. 7, 1999 2473
Ta ble 2. Effect of P h osp h or u s Liga n d s on
Ca r bosilyla tion of Cycloh exyla llen ea
entry
ligand
time (h)
yield (%)b
Z/Ec
1
2
3
4
5
6
7
14
24
12
72
72
85
82
82
20
80
77
92/8
P(OEt)3
PPh3
DPPF
DPPE
DPPF
77/23
86/14
75/25
75/25
75/25
a
All reactions were carried out under the following reaction
conditions: PhI (1.00 mmol); Bu3SnSiMe3 (1.00 mmol); cyclohexyl-
allene (2.00 mmol); Pd(dba)2 (0.050 mmol, 5 mol %); toluene (3.0
mL); temperature, 80 °C; ligand (1 equiv relative to Pd(dba)2);
To understand the effect of ligands on the catalytic
activity, we tested Pd(dba)2 with various phosphorus
ligands in a 1/1 molar ratio for the coupling reaction of
1-cyclohexylallene with 1a and 2. Table 2 listed the
yields, Z/E ratios, and time required for these experi-
ments. The results clearly show that Pd(dba)2 without
the presence of a phosphorus ligand is most active and
most stereoselective. The reaction required 7 h for
completion at 80 °C using Pd(dba)2 alone and gave
product 4a with a Z/E ratio of 98/2. Addition of PPh3,
P(OEt)3, or dppe (1 equiv) to the reaction mixture of
Pd(dba)2, 1a , and 2 greatly increases the period required
for completion of reaction and decreases the Z/E ratios
of the products (entries 2-6, Table 2).
b
reaction time, as indicated in the table. Isolated yields. c The Z/E
ratio of the allylic silane product was determined on the basis of
the 1H NMR integration method.
Sch em e 2
A possible mechanism for the present catalytic reaction
is shown in Scheme 2. The initial step likely involves
oxidative addition of organic halide 1 to a Pd(0) center
to give a palladium(II) intermediate. Coordination of
allene 3 to the palladium(II) center followed by migration
of the organic group to the central carbon of allene gives
a π-allyl palladium(II) species. Transmetalation with
organosilylstannane 2 followed by reductive elimination
yields the final allylic silane and tributyltin halide and
regenerates the palladium(0) species. Oxidative addition
of an organic halide to palladium(0) species11 and inser-
tion of allene into a palladium(II)-carbon bond12,13 are
well established. Transmetalation of a π-allyl palla-
dium(II) species with an organosilylstannane or disilane
has been reported previously, but the intimate mecha-
nism is not fully understood.3a The proposed formation
of tributyltin halide was evidenced by the observation of
Con clu sion
We have demonstrated a new regio- and stereoselective
method for the preparation of allylic silanes from allenes.
Although several methods for the synthesis of allylic
silanes were reported, the present methodology (eq 2)
appears to be a very convenient route that can introduce
a wide range of substituents to allylic silanes at the
internal sp2 carbons. Substituted allenes serve as excel-
lent unsaturated species in the three-component coupling
reactions. Further application in this direction is in
progress.
1
Bu3SnI in the H NMR spectra of the product mixtures
from reactions of aryl iodides with 2. It is noteworthy
that Bu3SnI was also observed in the palladium-catalyzed
reaction of 1,3-diene, aryl iodide, and 2.3a
The observation that phosphorus ligands diminish the
yield of allylic silanes may be understood in view of the
fact that strong donor ligands are known to impede olefin
coordination/insertion,14 which is central to the success
of the present three-component catalytic reaction (eq 2).
The decrease in Z/E ratio for monosubstituted allene in
the presence of a phosphorus ligand may be explained
by the fact that donor ligands readily promote anti-syn
rearrangement of π-allyl palladium(II) complexes via a
σ-allyl intermediate.15 The anti and syn forms of π-allyl
palladium(II) complexes are responsible for the formation
of Z and E isomers of allylic silanes, respectively.
Exp er im en ta l Section
Gen er a l Com m en ts. All reactions were run under
a
nitrogen atmosphere unless otherwise mentioned. All solvents
were dried according to known methods and distilled prior to
use. Pd(dba)2,16 n-butylallene,17 cyclohexylallene,17 phenyl-
allene,17 ethyl (Z)-3-iodoacrylate,18 5,5-dimethyl-3-bromo-2-
cyclohexen-1-one,19 3-iodo-2-cyclopenten-1-one,19 and 3-iodo-
2-cyclohexen-1-one19 were prepared by procedures previously
reported. Other reagents were commercially available and
used as purchased.
(11) (a) Tsuji, J . Organic Synthesis with Palladium Compounds;
Springer-Verlag: New York, 1980. (b) Hegedus, L. S. Transition Metals
in the Synthesis of Complex Organic Molecules; University Science
Books: Mill Valley, CA, 1994; Chapter 9.
(12) Shimizu, I.; Tsuji, J . Chem. Lett. 1984, 233-236.
(13) Stevens, R. R.; Shier, G. D. J . Organomet. Chem. 1970, 21, 495-
499.
(14) Yamamoto, Y.; Al-Masum, M.; Fujiwara, N. Chem. Commun.
1996, 381-382.
(15) (a) Tibbetts, D. L.; Brown, T. L. J . Am. Chem. Soc. 1970, 92,
3031-3034. (b) Powell, J .; Shaw, B. L. J . Chem. Soc. (A) 1967, 1839.
(16) Takahashi, Y.; Ito, T.; Sakai, S.; Ishii, Y. J . Chem. Soc., Chem.
Commun. 1970, 1065-1066.
(17) Brandsma, L.; Verkruijisse, H. D. Synthesis of Acetylenes,
Allenes and Cumulenes; Elsevier: New York, 1981.
(18) Ma, S.; Lu, X.; Li, Z. J . Org. Chem. 1992, 57, 709-173.
(19) Piers, E.; Grierson, J . E.; Lau, C. K.; Nagakura, I. Can. J . Chem.
1982, 60, 210-223.

2474 J . Org. Chem., Vol. 64, No. 7, 1999
Wu et al.
Gen er a l P r oced u r e for Cou p lin g of Or ga n ic Ha lid e
(1), Silylsta n n a n e (2), a n d Allen e (3). A 50 mL round-
bottom flask containing Pd(dba)2 (0.0287 g, 0.0500 mmol) was
purged with nitrogen gas three times. To the flask were then
added toluene (3 mL), an organic halide (1.00 mmol), allene
(2.00 mmol), and 2 (1.00 mmol) via syringes. The reaction
mixture was heated with stirring at 80 °C for 7 h. The solution
changed color rapidly from purple red to pale yellow in the
first few minutes and maintained the same color during the
rest of the reaction. As the reaction approached completion, a
black precipitate of palladium metal surrounding the wall of
the flask appeared gradually. At the end of the reaction, the
solution was filtered through Celite. The filtrate was concen-
trated, and the residue was separated on a silica gel column
using hexane as eluent to give the desired product 4.
Compounds 4a -p were prepared according to this method.
Product yields of each reaction are listed in Table 1; important
spectral data of these compounds follow.
1.75 (s, 2 H), 4.15 (q, J ) 7.2 Hz, 2 H), 5.72 (d, J ) 12.4 Hz, 1
H), 6.58 (d, J ) 12.4 Hz, 1 H); 13C NMR (100 MHz, CDCl3) δ
-0.83 (q), 14.24 (q), 20.91 (q), 21.82 (q), 22.95 (t), 59.85 (t),
119.11 (d), 126.97 (s), 127.16 (s), 147.55 (d), 165.98 (s); IR (neat)
2925, 2855, 1726, 1253, 1168 cm-1; GC-EIMS m/z (rel
intensity) 240 (M+, 20), 195 (100); HRMS calcd for C13H24O2-
Si 240.1545, found 240.1549.
Tr im e t h yl(3-m e t h yl-2-(1-p h e n ylvin yl)-2-b u t e n yl)si-
la n e (4k ): 1H NMR (400 MHz, CDCl3) δ -0.33 (s, 9 H), 1.53
(s, 2 H), 1.76 (s, 3 H), 1.77 (s, 3 H), 4.95 (d, J ) 1.8 Hz, 1 H),
5.51 (d, J ) 1.8 Hz, 1 H), 7.25-7.34 (m, 5 H); 13C NMR (100
MHz, CDCl3) δ -0.59 (q), 20.68 (t), 21.99 (q), 22.63 (q), 113.91
(t), 125.43 (s), 126.67 (d), 127.25 (d), 128.21 (d), 131.95 (s),
140.29 (s), 150.63 (s); IR (neat) 3080, 2954, 2916, 848, 780,
701 cm-1; GC-EIMS m/z (rel intensity) 244 (M+, 95); HRMS
calcd for C16H24Si 244.1641, found 244.1652.
1-(4-(Z)-2-Cycloh exyl-1-[(1,1,1-tr im eth ylsilyl)m eth yl]-
1-eth en ylp h en yl)-1-eth a n on e (4n ): 1H NMR (400 MHz,
CDCl3) δ -0.17 (s, 9 H), 1.05-1.31 (m, 5 H), 1.65-1.75 (m, 5
H), 1.98 (s, 2 H), 2.13-2.24 (m, 1 H), 0.56 (s, 3 H), 5.42 (d, J
) 9.2 Hz, 1 H), 7.38 (d, J ) 8.0 Hz, 2 H), 7.84 (d, J ) 8.0 Hz,
2 H); 13C NMR (100 MHz, CDCl3) δ -1.05 (q), 20.32 (t), 25.93
(t), 26.01 (t), 26.48 (q), 32.92 (t), 38.13 (d), 126.72 (d), 128.28
(d), 134.37 (d), 135.21 (s), 149.95 (s), 197.82 (s); IR (neat) 2925,
2850, 1683, 1601, 846 cm-1; GC-EIMS m/z (rel intensity) 314
(M+, 48), 73 (100); HRMS calcd for C20H30OSi 314.2058, found
314.2056.
1-(4-(E)-2-Cycloh exyl-1-[(1,1,1-tr im eth ylsilyl)m eth yl]-
1-eth en ylp h en yl)-1-eth a n on e (4n ′): 1H NMR (400 MHz,
CDCl3) δ -0.17 (s, 9 H), 1.06-1.14 (m, 5 H), 1.75-1.63 (m, 5
H), 1.82 (s, 2 H), 1.96-2.01 (m, 1 H), 2.61 (s, 3 H), 5.15 (d, J
) 10 Hz, 1 H), 7.26 (d, J ) 8.0 Hz, 2 H), 7.90 (d, J ) 8.0 Hz,
2 H); 13C NMR (100 MHz, CDCl3) δ -1.49 (q), 25.64 (t), 25.89
(t), 26.51 (q), 29.32 (t), 33.76 (t), 37.66 (d), 128.14 (d), 138.65
(d), 133.13 (d), 134.98 (s), 135.21 (s), 148.39 (s), 197.96 (s); IR
(neat) 2926, 2850, 1685, 1602, 848 cm-1; GC-EIMS m/z (rel
intensity) 314 (M+, 39); HRMS calcd for C20H30OSi 314.2058,
found 314.2051.
Tr im eth yl(3-m eth yl-2-p h en yl-2-bu ten yl)sila n e (4a ): 1H
NMR (400 MHz, CDCl3) δ -0.20 (s, 9 H), 1.57 (s, 3 H), 1.72 (s,
3 H), 1.85 (s, 2 H), 7.10-7.23 (m, 5 H); 13C NMR (100 MHz,
CDCl3) δ -0.94 (q), 21.09 (q), 22.07 (q), 25.71 (t), 123.81 (s),
125.70 (d), 127.67 (d), 129.16 (d), 132.40 (s), 145.11 (s); IR
(neat) 3021, 2955, 845, 700 cm-1; GC-EIMS m/z (rel intensity)
218 (M+, 100), 203 (49); HRMS calcd for C14H22Si 218.1490,
found 218.1496.
(2-(4-Meth oxyp h en yl)-3-m eth yl-2-bu ten yl)(tr im eth yl)-
sila n e (4d ): 1H NMR (400 MHz, CDCl3) δ -0.18 (s, 9 H), 1.59
(s, 3 H), 1.72 (s, 3 H), 1.84 (s, 2 H), 3.78 (s, 3 H), 6.78 (d, J )
8.4 Hz, 2 H), 7.02 (d, J ) 8.4 Hz, 2 H); 13C NMR (100 MHz,
CDCl3) δ -0.95 (q), 21.08 (q), 22.07 (q), 25.67 (t), 55.11 (q),
112.98 (d), 123.51 (s), 130.10 (d), 131.78 (s), 137.42 (s), 157.53
(s); IR (neat) 3031, 2929, 1245, 1174, 1039 cm-1; GC-EIMS
m/z (rel intensity) 248 (M+, 100); HRMS calcd for C15H24OSi
248.1596, found 248.1598.
E t h yl 3-(2-m et h yl-1-((1,1,1-t r im et h ylsilyl)m et h yl)-1-
p r op en yl)ben zoa te (4f): 1H NMR (400 MHz, CDCl3) δ -0.18
(s, 9 H), 1.37 (t, J ) 7.2 Hz, 3 H), 1.56 (s, 3 H), 1.74 (s, 3 H),
1.88 (s, 2 H), 4.34 (q, J ) 7.2 Hz, 2 H), 7.27-7.34 (m, 2 H),
7.81-7.85 (m, 2 H); 13C NMR (100 MHz, CDCl3) δ -0.91 (q),
14.27 (q), 21.05 (q), 21.99 (q), 25.67 (t), 60.82 (t), 124.79 (s),
126.97 (d), 127.66 (d), 130.07 (d), 130.14 (s), 131.56 (s), 133.78
(d), 145.37 (s), 166.82 (s); IR (neat) 2982, 1721, 1252, 1201,
1107, 850 cm-1; GC-EIMS m/z (rel intensity) 290 (M+, 100);
HRMS calcd for C17H26O2Si 290.1695, found 290.1693.
Tr im eth yl(3-m eth yl-2-(2-th ien yl)-2-bu ten yl)sila n e (4
g): 1H NMR (400 MHz, CDCl3) δ -0.11 (s, 9 H), 1.78 (s, 3 H),
1.82 (s, 3 H), 1.94 (s, 2 H), 6.78 (d, J ) 3.6 Hz, 1 H), 6.93 (dd,
J ) 5.2 Hz, J ) 3.6 Hz, 1 H), 7.16 (d, J ) 5.2 Hz, 1 H); 13C
NMR (100 MHz, CDCl3) δ -1.13 (q), 21.70 (q), 22.55 (q), 26.76
(t), 123.27 (d), 125.14 (s), 125.69 (d), 126.14 (d), 127.08 (s),
147.04 (s); IR (neat) 3071, 2925, 1163, 973 cm-1; GC-EIMS
m/z (rel intensity) 224 (M+, 72); HRMS calcd for C12H20SSi
224.1055, found 224.1059.
3-(2-Meth yl-1-((1,1,1-tr im eth ylsilyl)m eth yl)-1-pr open yl)-
2-cyclop en ten -1-on e (4h ): 1H NMR (400 MHz, CDCl3) δ
-0.10 (s, 9 H), 1.68 (s, 3 H), 1.69 (s, 2 H), 1.70 (s, 3 H), 2.34-
2.37 (m, 2 H), 2.61-2.65 (m, 2 H), 5.84 (s, 1 H); 13C NMR (100
MHz, CDCl3) δ -1.05 (q), 21.27 (t), 21.78 (q), 22.43 (q), 31.28
(t), 34.82 (t), 128.32 (s), 129.31 (s), 131.56 (d), 180.37 (s), 209.87
(s); IR (neat) 2954, 1700, 1590 cm-1; GC-EIMS m/z (rel
intensity) 223 (M + 1+, 22); HRMS calcd for C13H22OSi
222.1434, found 222.1444.
Tr im eth yl((Z)-2-ph en yl-2-h epten yl)silan e (4o): 1H NMR
(400 MHz, CDCl3) δ -0.17 (s, 9 H), 0.90 (t, J ) 7.2 Hz, 3 H),
1.32-1.44 (m, 4 H), 1.96 (s, 2 H), 2.08 (q, J ) 7.2 Hz, 2 H),
5.47 (t, J ) 7.2 Hz, 1 H), 7.14-7.31 (m, 5 H); 13C NMR (100
MHz, CDCl3) δ -0.95 (q), 14.05 (q), 20.90 (t), 22.58 (t), 28.99
(t), 32.01 (t), 126.25 (d), 126.35 (d), 126.57 (d), 127.99 (d),
137.68 (s), 145.04 (s); IR (neat) 3023, 2956, 849, 753, 697 cm-1
;
GC-EIMS m/z (rel intensity) 246 (M+, 100); HRMS calcd for
C
16H26Si 246.1803, found 246.1803.
((Z)-2,3-Diph en yl-2-pr open yl)(tr im eth yl)silan e (4p): 1H
NMR (400 MHz, CDCl3) δ -0.16 (s, 9 H), 2.31 (s, 2 H), 6.54 (s,
1 H), 7.18-7.44 (m, 10 H); 13C NMR (100 MHz, CDCl3) δ -0.84
(q), 21.48 (t), 125.44 (d), 126.02 (d), 126.86 (d), 127.08 (d),
128.17 (d), 128.72 (d), 138.88 (s), 141.58 (s), 145.11 (s); IR (neat)
3023, 2953, 851, 755, 697 cm-1; GC-EIMS m/z (rel intensity)
266 (M+, 98); HRMS calcd for C18H22Si 266.1485, found
266.1491.
Ack n ow led gm en t. We thank the National Science
Council of Republic of China (Grant No. NSC 87-2119-
M-007-002) for support of this research.
Su p p or tin g In for m a tion Ava ila ble: Spectral data for
compounds 4b-c, 4e, 4j, 4l, and 4m and 1H NMR spectra of
compounds 4a -p . This material is available free of charge via
the Internet at http://pubs.acs.org.
E t h yl (2Z)-5-m et h yl-4-((1,1,1-t r im et h ylsilyl)m et h yl)-
2,4-h exa d ien on a te (4i): 1H NMR (400 MHz, CDCl3) δ -0.01
(s, 9 H), 1.27 (t, J ) 7.2 Hz, 3 H), 1.66 (s, 3 H), 1.69 (s, 3 H),
J O982307A