Highly efficient B(C6F5)3-catalyzed hydrosilylation of olefins

Article abstract of DOI:10.1021/jo016279z

A convenient and highly efficient method for the Lewis acid-catalyzed trans-selective hydrosilylation of alkenes has been developed. The mechanism of this novel protocol operates via direct addition of silylium type species across C=C bond followed by trapping of the resultant carbenium ion with boron-bound hydride. A number of diversely substituted silanes possessing both aryl and alkyl groups at silicon atom were efficiently prepared using this hydrosilylation methodology. The possibility to employ aryl-containing hydrosilanes in this reaction opens broad capabilities for the synthesis of alcohols via a trans-selective hydrosilylation/Tamao - Fleming oxidation sequence, complementary to the existing cis-selective hydroboration/oxidation protocol.

Full text of DOI:10.1021/jo016279z

1936
J . Org. Chem. 2002, 67, 1936-1940
High ly Efficien t B(C6F 5)3-Ca ta lyzed Hyd r osilyla tion of Olefin s†
Michael Rubin, Todd Schwier, and Vladimir Gevorgyan*
Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street,
Chicago, Illinois 60607-7061
vlad@uic.edu
Received November 12, 2001
A convenient and highly efficient method for the Lewis acid-catalyzed trans-selective hydrosilylation
of alkenes has been developed. The mechanism of this novel protocol operates via direct addition
of silylium type species across CdC bond followed by trapping of the resultant carbenium ion with
boron-bound hydride. A number of diversely substituted silanes possessing both aryl and alkyl
groups at silicon atom were efficiently prepared using this hydrosilylation methodology. The
possibility to employ aryl-containing hydrosilanes in this reaction opens broad capabilities for the
synthesis of alcohols via a trans-selective hydrosilylation/Tamao-Fleming oxidation sequence,
complementary to the existing cis-selective hydroboration/oxidation protocol.
In tr od u ction
only. Neither protocol allows the use of aryl-containing
silanes, which is unfortunate since the corresponding
hydrosilylation products have broad synthetic applica-
tions as precursors of alcohols via the Tamao-Fleming
oxidation protocol.6
Hydrosilylation of alkenes and alkynes is a very
practical and straightforward approach to organosilicon
compounds. A number of transition-metal complexes
effectively catalyze this reaction, providing cis stereo-
chemistry of addition.1 Recently, Lewis acid-assisted
methodologies, providing alternative trans stereochem-
istry of addition, have been developed.2,3,4 The first
approach, introduced by Oertle and Wetter,2a proceeds
via formation of a hydroalane species from AlCl3 and
hydrosilane, hydroalumination of the alkene, followed by
transmetalation of the resulting alane with hydrosilane2
(Scheme 1A). The second approach, developed by Yama-
moto,3 presumes reversible addition of Lewis acid to a
C-C multiple bond (alkyne or allene), trapping of the
formed carbenium ion of the zwitterionic intermediate
with silicon-bound hydride, followed by a transmetalation
step (Scheme 1B).5 The former protocol2 requires the use
of chloro-containing hydrosilanes, which are not easily
handled, whereas the later3,4 is limited to trialkylsilanes
It was reported by Lambert7 that the stoichiometric
reaction between ate-complex 4 and alkene 5 results in
formation of carbenium borate complex 6 (eq 1), which
proceeds via addition of a silylium species across a double
bond. Shortly thereafter, he showed that species 6 could
be obtained in situ in the presence of a catalytic amount
of Ph3C+[B(C6F5)4]- (7) and a stoichiometric amount of
Et3SiH. Addition of the silylium species to an alkene with
formation of 6 was followed by trapping of the resulting
carbocation with hydride delivered by Et3SiH, to ac-
complish the catalytic cycle (Scheme 2).8 The main
purpose of Lambert’s experiment was to investigate the
formation of â-silyl cationic species 6, rather than to
develop the hydrosilylation methodology.8 Accordingly,
the single experiment on hydrosilylation of olefin 5 which
was performed (in an NMR tube) and described in the
paper8 does not permit generalization of this approach.
Furthermore, the reaction described proceeds in two-
phase conditions (liquid-oil), which complicates isolation
of the products. Thus, motivated by the importance of
development of novel hydrosilylation methodologies1 and
intrigued by Lambert’s findings,7,8 we decided to (a)
explore the possibility to replace 7 with another catalyst
which would allow for performing the reaction under
more convenient homogenious conditions, (b) clarify the
stereochemistry of addition, and (c) investigate the scope
of this reaction targeting the use of aryl-containing
hydrosilanes. Herein we wish to report a hydrosilylation
protocol, which operates via direct addition of a silylium
* To whom correspondence should be addressed. Fax: (312) 355-
0836. Tel: (312) 355-3579.
† Dedicated to Prof. Yoshinori Yamamoto on the occasion of his 60th
Birthday.
(1) (a) Ojima I. In The Chemistry of Organic Silicon Compounds;
Patai, S., Rappoport, Z., Eds.; J ohn Wiley: Chichester, 1989; p 1479.
(b) Marciniec, B. Comprehensive Handbook on Hydrosilylation; Per-
gamon Press: Oxford, 1992. (c) Hiyama, T.; Kusumoto, T. In Compe-
hensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon
Press: Oxford, 1991; Vol. 8, p 763.
(2) (a) Oertle, K.; Wetter, H. Tetrahedron Lett. 1985, 26, 5511. (b)
Yamamoto, K.; Takemae, M. Synlett 1990, 259. (c) Kubota, T.; Endo,
M.; Hirahara, T. J pn. Pat. 09316087, 1997.
(3) (a) Asao N.; Sudo, T.; Yamamoto, Y. J . Org. Chem. 1996, 61,
7654. (b) Sudo, T.; Asao, N.; Gevorgyan, V.; Yamamoto, Y. J . Org.
Chem. 1999, 64, 2494.
(4) Song, Y.-S.; Yoo, B. R.; Lee, G.-H.; J ung, I. N. Organometallics
1999, 18, 3109.
(5) K. Yamamoto (ref 2b) questioned Oertle-Wetter’s (ref 2a)
mechanism for AlCl3-catalyzed hydrosilylation of alkenes, whereas
J ung (ref 4) confronted Y. Yamamoto’s mechanism (ref 3) for hydrosi-
lylation of alkynes. Both proposed alternative mechanisms presume
the addition of silylium species across a C-C multiple bond followed
by trapping of the resulting â-silyl cation with silicon-bound hydride.
However, these mechanisms are highly unlikely since, as is generally
accepted, the employment of a weekly coordinating counteranion is
necessary for the generation of silylium type species. For a review on
R3Si+, see: Reed, C. A. Acc. Chem. Res. 1998, 31, 325.
(6) For a review, see: J ones, G. R.; Landais, Y. Tetrahedron 1996,
52, 7599.
(7) Lambert, J . B.; Zhao, Y. J . Am. Chem. Soc. 1996, 118, 7867.
(8) Lambert, J . B.; Zhao, Y.; Wu, H. J . Org. Chem. 1999, 64, 2729.
10.1021/jo016279z CCC: $22.00 © 2002 American Chemical Society
Published on Web 02/26/2002

B(C6F5)3-Catalyzed Hydrosilylation of Olefins
J . Org. Chem., Vol. 67, No. 6, 2002 1937
Sch em e 1. Mech a n ism s for Hyd r osilyla tion in th e P r esen ce of Tr a d ition a l Lew is Acid s
Sch em e 2. La m ber t’s Mech a n ism for th e P h 3C+[B(C6F 5)4]--Ca ta lyzed Hyd r osilyla tion 8
Ta ble 1. B(C6F 5)3-Ca ta lyzed Hyd r osilyla tion of Styr en e
species across the double bond followed by trapping of
the formed carbenium ion with boron-bound hydride.
This novel methodology is highly efficient, convenient,
truly catalytic in Lewis acid and completely compatible
with both alkyl and arylsilanes (eq 2).
2a
silane
product 3
yield,a
%
1
2
3
4
5
6
7
8
Et3SiH
1a
1b
1c
1d
1e
1f
PhCH2CH2SiEt3
3a
3b
3c
3d
3e
3f
96b
95
95
NR
96
93
EtMe2SiH
Et2MeSiH
i-Pr3SiH
PhMe2SiH
Ph2MeSiH
Ph3SiH
PhCH2CH2SiMe2Et
PhCH2CH2SiMeEt2
PhCH2CH2Si(Pr-i)3
PhCH2CH2SiMe2Ph
PhCH2CH2SiMePh2
PhCH2CH2SiPh3
1g
1h
3g
3h
92
Ph2SiH2
PhCH2CH2SiPh2H
85c
a
b
Isolated yields. 57% yield was obtained under conditions of
AlCl3-catalyzed reaction.4 c Traces of double-silylation product (3i)
Resu lts a n d Discu ssion
were detected by GC/MS analysis of the crude reaction mixture.
Since reversible formation of organic solvent-soluble
ate-complex 9 from hydrosilane 1 and borane 8 was
documented by Piers9 (eq 3),10 we decided to test if the
silylium cation from complex 9, analogous to that from
complex 4, would undergo addition across the C-C
double bond, and the resulting carbenium ion would be
trapped with hydride. Given that both steps proceed, it
would allow for the development of a novel preparatively
convenient catalytic hydrosilylation protocol.
larly effective, affording the corresponding hydrosilyla-
tion products 3b,c in excellent yields. As expected,
TIPS-H (1d ) did not undergo hydrosilylation at all.11
Remarkably, aryl-containing hydrosilanes (1e-h ) were
equally effective, leading to (3e-h ) in excellent yields
(Table 1, entries 5-9). To the best of our knowledge, this
is the first example of arylsilanes efficiently employed in
Lewis acid-catalyzed hydrosilylation. Inspired by the
successful results in the hydrosilylation of styrene, we
tested this method for other types of alkene substrates.
The results are summarized in Table 2. Diversely sub-
stituted styrene derivatives (2b-g) underwent hydrosi-
lylation smoothly to produce the corresponding silanes
in very high yields. Amazingly, even extremely polymer-
izable under cationic conditions, indene (2g) gave high
yield of silane 3o. Aliphatic alkenes 2h -l efficiently
reacted with various silanes, providing 3p -u in excellent
yields (Table 2, entries 7-12). Hydrosilylation of the
double bond in cyclohexenes showed little sensitivity
toward substitution pattern. Thus, 10 mol % of catalyst
was needed to complete formation of 3t (Table 2, entry
11). Although trace amounts of double silylation products
were observed employing silicon dihydride 1h (Table 1,
entry 8, and Table 2, entry 12), the corresponding
monosilylation products, synthetically useful1 hydrosi-
We found, indeed, that styrene (2a ) underwent smooth
hydrosilylation with 1.2 equiv of Et3SiH (1a ) in the
presence of 5 mol % of B(C6F5)3 to give the corresponding
tetraalkylsilane (3a ) in 96% yield (eq 1, Table 1, entry
1). No side polymerization processes, typical for the
traditional Lewis acid-catalyzed hydrosilylation method-
ologies,4 were observed! Trialkylsilanes 1b,c were simi-
(9) (a) Blackwell, J . M.; Foster, K. L.; Beck, V. H.; Piers, W. E. J .
Org. Chem. 1999, 64, 4887. (b) Parks, D. J .; Blackwell, J . M.; Piers,
W. E. J . Org. Chem. 2000, 65, 3090.
(10) For involvement of 8 in reduction of alcohols, ethers, and
carboxylic acids, see: (a) Gevorgyan, V.; Liu, J .-X.; Rubin, M.; Benson,
S.; Yamamoto, Y. Tetrahedron Lett. 1999, 40, 8919. (b) Gevorgyan, V.;
Rubin, M.; Benson, S.; Liu, J .-X.; Yamamoto, Y. J . Org. Chem. 2000,
65, 6179. (c) Gevorgyan, V.; Rubin, M.; Liu, J .-X.; Yamamoto, Y. J .
Org. Chem. 2001, 66, 1672.
(11) It was shown that 1d does not form ate-complex 8; see ref 9b.

1938 J . Org. Chem., Vol. 67, No. 6, 2002
Ta ble 2. Hyd r osilyla tion of Differ en tly Su bstitu ted Alk en es
Rubin et al.
a
b
Isolated yields. Yields obtained under conditions of AlCl3-catalyzed hydrosilylation4 are shown in parentheses. c Reaction was
d
performed on a 5 mmol scale with 10 mol % of B(C6F5)3. Ratio cis/trans ) 96:4. Traces of double-silylation product were detected by
GC/MS analysis of crude reaction mixture; formation of the isomeric trans-3u was not detected by GC/MS analysis of the crude reaction
mixtures.
Sch em e 3. B(C6F 5)3-Ca ta lyzed Hyd r osilyla tion of
Alk en es
As discussed above, this hydrosilylation reaction oper-
ates via fast equilibration of 1 and 8 forming complex 9
(eq 3, Scheme 3),9 slow addition of silylium cation13 of 9
across the double bond of alkene 2 affording the â-silyl-
carbenium complex 10, and fast trapping of 10 with
boron-bound hydride to produce the hydrosilylation
product 3 and regenerate the catalyst (Scheme 3). This
mechanism is supported by the following experiments.
The observed absence of an isotope effect (kH/kD ) 0.96
( 0.05) presumes formation of 10 in a rate-determining
step,14 which then is quickly quenched by boron-carried
hydride (Scheme 3, path A). An alternative pathway for
hydride delivery, similar to the last step in Lambert’s
mechanism (Scheme 2),8 involving delivery of hydride to
10 by hydrosilane (Scheme 3, path B) was ruled out based
on the results of the following experiments. Hydrosily-
lation of styrene 2a with a (1:1) mixture of Ph3SiD/
i-Pr3SiH gave PhCHDCH2SiPh3 (3g-d1) exclusively. Since
it is well-known that i-Pr3SiH (1d ) is a superior hydride
donor compared to Ph3SiH (1g)15 and neither formation
lanes 3h ,u , were obtained in very good yields. Initial
experiments demonstrated that properly protected oxygen-
containing olefins (e.g., 2m ) can be successfully employed
in the B(C6F5)3-catalyzed hydrosilylation reaction (Table
2, entry 13). Notably, due to relatively low oxophilicity
of B(C6F5)3, we were able to complete hydrosilylation of
2m using 5 mol % of this Lewis acid only.12 Comparison
of yields obtained using novel B(C6F5)3-catalyzed and
traditional AlCl3-mediated hydrosilylation methodologies
(yields in parentheses) clearly demonstrates the superi-
ority of this new protocol.
(13) Here and below formation or involvement of free silylium cation
is not presumed.
(12) It was reported that switching from fully hydrocarbon to
oxygen-containing substrates in the traditional Lewis acid-mediated
hydrosilylation of alkynes required an increase of the amount of AlCl3
used from 0.2 to 1.2 equiv. See ref 3b.
(14) Transformation 9 to 10 is the only step which does not involve
formation/breakage of any of element-H(D) bonds.
(15) Mayr, H.; Basso, N.; Hagen, G. J . Am. Chem. Soc. 1992, 114,
3060.

B(C6F5)3-Catalyzed Hydrosilylation of Olefins
J . Org. Chem., Vol. 67, No. 6, 2002 1939
compounds 3b,26 3g,27 3h ,28 3j,k ,29 3o,4 3m ,30 and 3q,31 for
which spectral data presented in the literature is incomplete.
(+) and (-) represent positive and negative intensities of
signals in 13C DEPT-135 experiment.
of complex 9 from 1d nor deuterium scrambling between
1d and 1g-d1 is possible,9b it becomes apparent that
hydride is delivered by boron and not by silicon.16
Like traditional Lewis acid-assisted methodologies,2-4
this proposed B(C6F5)3-catalyzed hydrosilylation protocol
operates via trans stereochemistry of addition, which was
confirmed by hydrosilylation of 2l (Table 2, entries 11,
12, eq 4). “Bulky hydride” prefers to attack carbocation
10l from the less sterically hindered face, affording cis
products 3t,u . Alcohol 11 with stereochemistry opposite
to one provided by hydroboration/oxidation sequence,
could be easily obtained from arylsilane 3t by Tamao-
Fleming oxidation (eq 4).
Gen er a l P r oced u r e for H yd r osilyla t ion of Alk en es.
The preparation of 3a is representative. To a stirred solution
of B(C6F5)3 (26 mg, 5 mol %) in anhydrous CH2Cl2 (1 mL) was
added Et3SiH (1a ) (1.2 mmol, 140 mg, 193 µL), followed by
addition of styrene (2a ) (1 mmol, 104 mg, 114 µL). The reaction
mixture was stirred at room temperature and the reaction
course was monitored by GC/MS analysis. After the reaction
was complete (10-12 h for 3a ), the mixture was filtered
through a short column (silica gel, CH2Cl2 as an eluent) and
concentrated. Purification by column chromatography (silica
gel, hexane as an eluent) gave 212 mg of 3a (96%).
3b: 1H NMR (CDCl3, 500.13 MHz) δ 7.39 (t, 2H), 7.32 (d,
2H), 7.28 (t, 1H), 2.74 (m, 2H), 1.07 (t, J ) 7.9 Hz, 3H), 1.01
(m, 2H), 0.64 (q, J ) 7.9 Hz, 2H), 0.12 (s, 6H); 13C NMR (CDCl3,
125.76 MHz) δ 145.9, 128.77 (+), 128.26 (+), 125.96 (+), 30.54
(-), 17.42 (-), 7.85 (+), 7.33 (-), -3.47 (+); FT-IR (film, cm-1
)
3060, 3025, 2951, 2909, 2879, 1493, 1453, 1414, 1249, 1008,
958, 896, 834, 772, 697; GC/MS m/z 192 (M+, <1), 177 (M -
Me, 5), 163 (M - Et, 90), 59 (100).
3g: 1H NMR (CDCl3, 500.13 MHz) δ 7.61 (m, 6H), 7.84-
7.41 (m, 9H), 7.30 (m, 2H), 7.24-7.21 (m, 3H), 2.83 (m, 2H),
1.79 (m, 2H); 13C NMR (CDCl3, 125.76 MHz) δ 145.4, 136.1
(+), 135.3, 130.0 (+), 128.8 (+), 128.4 (+), 128.2 (+), 126.1 (+),
30.4 (-), 15.9 (-); GC/MS m/z 286 (M+ - C6H6, 30), 259 (Ph3-
Si+, 100).
In conclusion, an efficient protocol for the Lewis acid-
catalyzed hydrosilylation of alkenes was developed. A
mechanism, involving addition of silylium cation across
the CdC bond followed by trapping of the formed carbe-
nium cation with boron-bound hydride was confirmed.
Tolerance of this novel Lewis acid-catalyzed methodology
toward aryl-containing hydrosilanes allows for its broad
application for the synthesis of alcohols via trans-
selective hydrosilylation/Tamao-Fleming oxidation se-
quence, complementary to the existing cis-selective hy-
droboration/oxidation protocol.
3h : 1H NMR (CDCl3, 400.13 MHz) δ 7.66 (m, 4H), 7.46 (m,
6H), 7.33 (t, 2H), 7.27 (m, 3H), 5.00 (t, J ) 3.7 Hz, 1H), 2.86
(m, 2H), 1.61 (m, 2H); 13C NMR (CDCl3, 125.76 MHz) δ 144.9,
135.7 (+), 134.6, 130.2 (+), 128.9 (+), 128.6 (+), 128.4 (+), 126.3
(+), 31.0 (-), 14.8 (-); FT-IR (film, cm-1) 3066, 3049, 3023,
2923, 2121, 1495, 1453, 1428, 1117, 803, 733, 698; GC/MS m/z
259 (<1), 210 (M+ - C6H6, 55), 183 (Ph2HSi+, 95), 132 (M+
2C6H6, 100).
-
3j: 1H NMR (CDCl3, 500.13 MHz) δ 7.15 (m, 4H), 2.63 (m,
2H), 2.37 (s, 3H), 1.01 (t, J ) 8.0 Hz, 9H), 0.95 (m, 2H), 0.62
(q, J ) 8.0 Hz, 6H); 13C NMR (CDCl3, 125.76 MHz) δ 143.1,
135.3, 129.4 (+), 128.0 (+), 30.0 (-), 21.4 (+), 14.3 (-), 7.9 (+),
3.7 (-); FT-IR (film, cm-1) 3011, 2950, 2909, 2877, 1512, 1457,
1414, 1236, 1171, 1010, 967, 802, 766, 732; GC/MS m/z 234
(M+, <1), 205 (M - Et, 90), 87 (100).
Exp er im en ta l Section
NMR spectra were recorded on Bruker Avance DRX-500
(500 MHz) and DPX-400 (400 MHz) instruments. IR spectra
were recorded on a Genesis II FT-IR Mattson spectrometer.
GC/MS analysis was performed on a Hewlett-Packard Model
6890 GC interfaced to a Hewlett Packard Model 5973 mass
selective detector (15 m × 0.25 mm capillary column, HP-5MS).
Column chromatography was carried out employing Merck
silica gel (Kieselgel 60, 63-200 µm). Elemental analysis was
performed by Midwest Microlab, LLC (Indianapolis, IN).
3k : 1H NMR (CDCl3, 500.13 MHz) δ 7.27 (d, J ) 8.4 Hz,
2H), 7.17 (d, J ) 8.4 Hz, 2H), 2.62 (m, 2H), 1.00 (t, J ) 7.9
Hz, 9H), 0.89 (m, 2H), 0.59 (q, J ) 7.9 Hz, 6H); 13C NMR
(CDCl3, 125.76 MHz) δ 144.4, 131.5, 129.5 (+), 128.8 (+), 29.9
(-), 14.0 (-), 7.9 (+), 3.7 (-); FT-IR (film, cm-1) 3028, 2951,
2907, 2877, 1489, 1459, 1412, 1235, 1174, 1092, 1010, 799, 756,
728; GC/MS m/z 254 (M+, <1), 225 (M - Et, 50), 87 (100).
All manipulations were conducted under argon atmosphere
using a combination of glovebox and standard Schlenk tech-
niques. Anhydrous dichloromethane was purchased from Al-
drich and stored over calcium hydride. B(C6F5)3 is commer-
cially available, but for our purpose it was prepared according
to the known procedure.17 Deuterated silanes Et3SiD and Ph3-
SiD were prepared by reduction of the corresponding com-
mercially available (Aldrich, Acros Organics) chlorosilanes
with LiAlD4 in anhydrous ether.18 All other chemicals and
solvents were purchased from Aldrich, Acros Organics and
used without additional purification.
3
3l: 1H NMR (CDCl3, 500.13 MHz) δ 7.18 (dd, J HH ) 8.5
4
3
3
Hz, J HF ) 5.6 Hz, 2H), 6.99 (ps.-t, J HH ≈ J HF ) 8.7 Hz, 2H),
(21) (a) Lebedev, V. N.; Balagurova, E. V.; Dolgushin, F. M.;
Yanovskii, A. I.; Zakharkin, L. I. Russ. Chem. Bull. 1997, 46, 550. (b)
Fleming, I.; Henning, R.; Parker, D. C.; Plaut, H. E.; Sanderson, P. E.
J . J . Chem. Soc., Perkin Trans. 1 1995, 317.
(22) Magomedov, G. K.-I.; Shkol’nik, O. V.; Druzhkova, G. V. J . Gen.
Chem. USSR (Engl. Transl.) 1983, 53, 342.
(23) Gilman, M. J . Org. Chem. 1956, 21, 254.
Products 3a ,19 3c,20 3e,21 3f,22 3i,23 3p ,s,24 and 1125 are
known compounds, and their analytical data were in agree-
ment with the literature data. Spectral data for new com-
pounds 3l,n ,r ,t-v are provided below, as well as for known
(24) Matsumoto, A.; Ito, Y. J . Org. Chem. 2000, 65, 5707.
(25) (a) Cannone, P.; Bernatchez, M. J . Org. Chem. 1987, 52, 4025.
(b) J ones, J . B.; Takemura, T. Can. J . Chem. 1982, 60, 2950. (c)
Kobayashi, Y.; Takahisa, E.; Nakano, M.; Watatani, K. Tetrahedron
1997, 53, 1627.
(26) Green, M.; Spencer, J . L.; Stone, F. G. A.; Tsipis, C. A. J . Chem.
Soc., Dalton Trans. 1977, 1519.
(16) This approach was used by Piers to establish the hydride carrier
in B(C6F5)3-catalyzed reduction of carbonyl function with hydrosilanes.9b
(17) (a) Massey, A. G.; Park, A. J . J . Organomet. Chem. 1964, 2,
254. (b) Massey, A. G.; Park, A. J . J . Organomet. Chem. 1966, 5, 218.
(18) (a) Gilbert, J . C.; Giamalva, D. H. J . Org. Chem. 1985, 50, 2586.
(b) Oba, M.; Nishiyama, K. Tetrahedron 1994, 50, 10193.
(19) Donskaya, N. A.; Yur’eva, N. M.; Voevodskaya, T. I.; Sigeev,
A. S.; Beletskaya, I. P. Russ. J . Org. Chem. 1994, 30, 853.
(20) Kuncova, G.; Chvalovsky, V. Collect. Czech. Chem. Commun.
1980, 45, 2085.
(27) Bourne, A. J .; J arvie, A. W. P.; Holt, A. J . Chem. Soc. C 1970,
1740.
(28) Takahashi, T.; Hasegawa, M.; Suzuki, N.; Saburi, M.; Rousset,
C. J .; Fanwick, P. E.; Nigishi, E.-I. J . Am. Chem. Soc. 1991, 113, 8564.
(29) Kakiuchi, F.; Tanaka, Y.; Chatani, N.; Murai, S. J . Organomet.
Chem. 1993, 456, 45.
(30) Skoda-Foeldes, R.; Kollar, L.; Heil, B. J . Organomet. Chem.
1991, 408, 297.
(31) Choi, G. M.; Yeon, S. H.; J in, J .; Yoo, B. R.; J ung, I. N.
Organometallics 1997, 16, 5158.

1940 J . Org. Chem., Vol. 67, No. 6, 2002
Rubin et al.
2.63 (m, 2H), 0.99 (t, J ) 7.9 Hz, 9H), 0.90 (m, 2H), 0.59 (q, J
2956, 2918, 2830, 1449, 1436, 1250, 1110, 868, 819, 767, 731,
700; GC/MS m/z 232 (M+, 1), 217 (M - Me, <1), 135 (PhMe2-
Si+, 100). Anal. Calcd for C15H24Si: C, 77.51; H, 10.41.
Found: C, 77.68; H, 10.44.
1
) 7.9 Hz, 6H); 13C NMR (CDCl3, 125.76 MHz) δ 161.5 (d, J CF
3
) 242.7 Hz), 141.5, 129.4 (d, J CF ) 19.2 Hz) (+), 115.4 (d,
2J CF ) 24.5 Hz) (+), 29.7 (-), 14.2 (-), 7.9 (+), 3.7 (-); 19F
NMR (CDCl3, 470.59 MHz) δ -120.0; FT-IR (film, cm-1) 3037,
2952, 2908, 2878, 1601, 1508, 1459, 1414, 1226, 1155, 1010,
967, 821, 775, 737; GC/MS m/z 209 (M - Et, 60), 87 (100).
Anal. Calcd for C14H23FSi: C, 70.53; H, 9.72. Found: C, 70.51;
H, 9.76.
3u : 1H NMR (CDCl3, 400.13 MHz) δ 7.66 (m, 4H), 7.39 (m,
6H), 4.86 (d, J ) 4.4 Hz, 1H), 2.10 (m, 1H), 1.73-1.46 (m, 8H),
1.31 (m, 1H), 1.02 (d, J ) 7.2 Hz, 3H); 13C NMR (CDCl3, 125.76
MHz) δ 135.9 (+), 135.7 (+), 135.2, 135.1, 129.8 (+), 129.7 (+),
128.40 (+), 128.35 (+), 35.0 (-), 30.4 (+), 28.5 (+), 28.2 (-),
23.8 (-), 22.1 (-), 17.0 (+); FT-IR (film, cm-1) 3067, 3049, 2921,
2850, 2120, 1428, 1114, 894, 946, 819, 806, 733, 634; GC/MS
m/z 280 (M+, 2), 202 (M+ - C6H6, 20), 183 (Ph2HSi+, 100). Anal.
Calcd for C19H24Si: C, 81.36; H, 8.62. Found: C, 81.29; H, 8.59.
3v: 1H NMR (CDCl3, 500.13 MHz) δ 3.71 (t, J ) 6.5 Hz,
2H), 1.59 (ps-quint. J ) 7.0 Hz, 2H), 1.40 (m, 2H), 1.10-1.07
(m, 21H), 0.95 (t, J ) 7.9 Hz, 9H), 0.53 (q, J ) 7.9 Hz, 6H);
13C NMR (CDCl3, 125.76 MHz) δ 63.4 (-), 37.5 (-), 20.5 (-),
3m : 1H NMR (CDCl3, 500.13 MHz) δ 7.33 (t, 2H), 7.28 (d,
2H), 7.22 (t, 1H), 2.93 (sextet, J ) 7.1 Hz, 1H), 1.34 (d, J )
6.9 Hz, 3H), 1.05 (dd, J ) 14.8, 7.5 Hz, 1H), 0.97 (dd, J ) 14.8,
7.3 Hz, 1H), 0.94 (t, J ) 7.9 Hz, 9H), 0.54-0.42 (m, 6H); 13C
NMR (CDCl3, 125.76 MHz) δ 150.6, 128.7 (+), 127.0 (+), 126.2
(+), 36.6 (+), 26.9 (+), 22.0 (-), 7.9 (+), 4.1 (-); FT-IR (film,
cm-1) 3060, 3025, 2953, 2906, 2874, 1601, 1491, 1453, 1412,
1374, 1237, 1011, 794, 758, 739, 698; GC/MS m/z 205 (M -
Et, 60), 163 (100).
18.4 (+), 12.4 (+), 11.5 (-), 7.9 (+), 3.7 (-); FT-IR (film, cm-1
)
3n : 1H NMR (CDCl3, 400.13 MHz) δ 7.09 (m, 4H), 2.87-
2.70 (m, 4H), 1.99 (m, J ) 12.8 Hz, 1H), 1.58 (qd, J ) 12.6,
5.7 Hz, 1H), 1.16 (tdd, J ) 12.3, 5.8 Hz, 2.5 Hz, 1H), 1.01 (t,
J ) 7.9 Hz, 9H), 0.64 (q, J ) 7.9 Hz, 6H); 13C NMR (CDCl3,
100.61 MHz) δ 137.9, 137.3, 129.3 (+), 128.8 (+), 125.4 (×2)
(+), 30.7 (-), 30.5 (-), 24.6 (-), 19.5 (+), 7.7 (+), 2.0 (-); GC/
MS m/z 246 (M+, 2), 217 (M - Et, 40), 129 (100).
2941, 2868, 1463, 1110, 1014, 891, 721, 681; GC/MS m/z 301
(M+ - i-Pr, 10), 115 (Et3Si+, 100). Anal. Calcd for C19H44OSi2:
C, 66.20; H, 12.87. Found: C, 66.52; H, 12.71.
E xp er im en t s on H /D Isot op e E ffect Mea su r em en t .
Styrene 2a was subjected to the reaction with a 5-fold excess
of Et3SiH/Et3SiD mixture (1:1) under standard reaction condi-
tions. The mixture of hydrosilylation products 3a /3a -d1 was
separated from Et3SiOSiEt3 by column chromatography on
silica gel (eluent hexane) and deuterium purity was deter-
mined by integration of signals at δ 2.67 vs 0.95 in the 1H
NMR spectra (CDCl3, 500.13 MHz). Determined H/D product
isotope effect: 0.96 ( 0.05.
Ta m a o-F lem in g oxid a tion of 2l. The reaction was
performed according to the modified Fleming procedure.32
Peracetic acid (Aldrich, 32% solution in acetic acid, 5 mL) was
added dropwise at 0 °C to a stirred mixture of silane 2l (3
mmol), potassium bromide (500 mg), and anhydrous sodium
acetate (1.2 g) in glacial acetic acid (15 mL). The mixture was
allowed to warm to room temperature and stirred for an
additional 18 h. Then the reaction mixture was diluted (ether)
and carefully neutralized (NaHCO3 solution). The Etheral
layer was washed (Na2SO3, and brine) and dried (MgSO4).
Ether was removed at ambient pressure, and the residue was
purified by preparative column chromatography (eluent hex-
ane, then hexanes-ether 5:1) to obtain cis-2-methylcyclohex-
anol (11) as a colorless oil: yield 294 mg (86%).
3o: 1H NMR (CDCl3, 500.13 MHz) δ 7.30 (m, 2H), 7.21 (m,
2H), 3.10 (dd, J ) 15.2, 9.0 Hz, 2H), 2.96 (dd, J ) 15.2, 11.1
Hz, 2H), 1.81 (tt, J ) 11.1, 9.0 Hz, 1H), 1.08 (t, J ) 7.9 Hz,
9H), 0.70 (q, J ) 8.0 Hz, 6H); 13C NMR (CDCl3, 125.76 MHz)
δ 145.4, 126.3 (+), 124.6 (+), 35.5 (-), 23.8 (+), 8.2 (+), 3.2
(-); FT-IR (film, cm-1) 3071, 3026, 2953, 2909, 2875, 1459,
1415, 1328, 1239, 1016, 833, 743; GC/MS m/z 232 (M+, 5), 203
(M - Et, 20), 116 (100).
3q: 1H NMR (CDCl3, 400.13 MHz) δ 7.34 (t, 2H), 7.25 (m,
3H), 2.69 (t, J ) 7.6 Hz, 2H), 1.67 (m, 2H), 0.98 (t, J ) 7.9 Hz,
3H), 0.62 (m, 2H), 0.54 (q, J ) 7.9 Hz, 2H), 0.02 (s, 6H); 13C
NMR (CDCl3, 100.61 MHz) δ 142.8, 128.5 (+), 128.3 (+), 125.7
(+), 40.1 (-), 26.2 (-), 14.8 (-), 7.4 (+), 6.9 (-), -3.9 (+); FT-
IR (film, cm-1) 3085, 3063, 3031, 2952, 2924, 1604, 1496, 1456,
1415, 1245, 1170, 1012, 959, 834, 792, 745, 698; GC/MS m/z
191 (M - Me, 10), 177 (M - Et, 100).
3r : 1H NMR (CDCl3, 500.13 MHz) δ 7.59 (m, 2H), 7.42 (m,
3H), 1.75-1.65 (m, 5H), 1.49 (m, 1H), 1.28-1.16 (m, 3H), 1.00
(m, 2H), 0.83 (d, J ) 6.8 Hz, 2H), 0.36 (s, 6H); 13C NMR (CDCl3,
125.76 MHz) δ 140.8, 133.9 (+), 129.1 (+), 128.1 (+), 37.4 (-),
34.8 (+), 27.0 (-), 26.7 (-), 25.1 (-), -1.4 (+); FT-IR (film,
cm-1) 3068, 2921, 2851, 1447, 1427, 1249, 1112, 830, 725, 705;
GC/MS m/z 217 (M - Me, 2), 154 (M+ - C6H6, 30), 135 (PhMe2-
Si+, 100). Anal. Calcd for C15H24Si: C, 77.51; H, 10.41.
Found: C, 77.68; H, 10.43.
Ack n ow led gm en t . The support of the Petroleum
Research Fund (AC1-36370), administered by the Ameri-
can Chemical Society, is gratefully acknowledged.
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
charts for 3n . This material is available free of charge via the
Internet at http://pubs.acs.org.
3t: 1H NMR (CDCl3, 500.13 MHz) δ 7.56 (m, 2H), 7.39 (m,
3H), 2.04 (m, 1H), 1.74 (m, 1H), 1.57-1.47 (m, 6H), 1.24 (m,
1H), 1.13 (m, 1H), 0.98 (d, J ) 7.2 Hz, 3H), 0.33 (s, 3H), 0.32
(s, 3H); 13C NMR (CDCl3, 125.76 MHz) δ 140.0, 134.3 (+), 129.0
(+), 128.0 (+), 35.6 (-), 30.7 (+), 29.7 (+), 28.8 (-), 22.4 (-),
21.6 (-), 16.7 (+), -3.1 (+); FT-IR (film, cm-1) 3064, 3012,
J O016279Z
(32) Fleming, I.; Lawrence, N. J . J . Chem. Soc., Perkin Trans. 1
1992, 3309.