Copper(I) tert-butoxide-promoted 1,4 Csp-to-O silyl migration: Generation of vinyl copper equivalents and their stereospecific cross-coupling with allylic, aryl, and vinylic halides

Article abstract of DOI:10.1021/jo025973r

Successive treatment of the (Z)-γ-trimethylsilyl allylic alcohols with copper(I) tert-butoxide and allylic halides followed by the tetrabutylammonium fluoride-assisted hydrolysis produced the allylation products, 2,5-alkadien-1-ols, with complete retention of configuration. Similar treatment of the organometallic intermediates with aryl and vinylic halides in the presence of palladium(O) catalyst gave the corresponding cross-coupling products in good yields. The stereoselective preparation of the starting materials is also described.

Full text of DOI:10.1021/jo025973r

2
Cop p er (I) ter t-Bu toxid e-P r om oted 1,4 Csp -to-O Silyl Migr a tion :
Gen er a tion of Vin yl Cop p er Equ iva len ts a n d Th eir Ster eosp ecific
Cr oss-Cou p lin g w ith Allylic, Ar yl, a n d Vin ylic Ha lid es
Haruhiko Taguchi, Kazushi Ghoroku, Makoto Tadaki, Akira Tsubouchi, and Takeshi Takeda*
Department of Applied Chemistry, Tokyo University of Agriculture and Technology,
Koganei, Tokyo 184-8588, J apan
takeda-t@cc.tuat.ac.jp
Received May 27, 2002
Successive treatment of the (Z)-γ-trimethylsilyl allylic alcohols with copper(I) tert-butoxide and
allylic halides followed by the tetrabutylammonium fluoride-assisted hydrolysis produced the
allylation products, 2,5-alkadien-1-ols, with complete retention of configuration. Similar treatment
of the organometallic intermediates with aryl and vinylic halides in the presence of palladium(0)
catalyst gave the corresponding cross-coupling products in good yields. The stereoselective
preparation of the starting materials is also described.
In tr od u ction
of alkenyl- and alkynylsilanes have also been reported
through the formation of a silicate.5
The increased importance of organosilicon compounds
in organic synthesis has led to considerable interest in
organosilicon-based cross-coupling reactions. Palladium-
catalyzed cross-coupling reactions of functionalized alk-
enylsilanes with organic halides have been extensively
studied for the preparation of various olefins.1 To facili-
tate these reactions, however, the activation of the Si-C
bond by introduction of the electronegative substituents
on the silicon atom2 or a silacyclobutane moiety3 is
essential. The use of a strong accelerating additive such
as tris(diethylamino)sulfonium difluorotrimethylsilicate
is an alternative way for effecting the reaction through
the formation of a hypervalent silicate.4 Recently the
copper(I) salt promoted self- and cross-coupling reactions
The Brook-type rearrangement is another attractive
way to convert organosilicon compounds into reactive
organometallic species, which are subsequently utilized
for organic synthesis. In this context, efforts have been
3
focused on 1,4 Csp -to-O silyl migration for the preparation
2
of various carbanions.6 In contrast, 1,4 Csp -to-O silyl
migration, which generates vinylmetal species, has pro-
vided so far little synthetic significance due to unfavor-
able equilibrium to the rearrangement products.7 Al-
2
though the 1,4 Csp -to-O silyl migration of sodium salt of
3-hydroxy-2-(trimethylsilyl)furan was observed, the re-
sulting carbanion at the 2-position could not react with
(5) (a) Yoshida, J .; Tamao, K.; Kakui, T.; Kumada, M. Tetrahedron
Lett. 1979, 1141-1144. (b) Urata, H.; Fuchikami, T. Tetrahedron Lett.
1991, 32, 91-94. (c) Lermontov, S. A.; Rakov, I. M.; Zefirov, N. S.
Tetrahedron Lett. 1996, 37, 4051-4054. (d) Kang, S.-K.; Kim, T.-H.;
* Corresponding author. Tel & Fax: 81-42-388-7034.
(1) (a) Hatanaka, Y.; Hiyama, T. Synlett 1991, 845-853. (b) Hiyama,
T.; Hatanaka, Y. Pure Appl. Chem. 1994, 66, 1471-1478. (c) Horn, K.
H. Chem. Rev. 1995, 95, 1317-1350. (d) Hiyama, T. In Metal-catalyzed
Cross-coupling Reactions; Diederich, F.; Stang, P. J ., Eds. Organosilicon
Compounds in Cross-coupling Reactions; Wiley-VCH: Weinheim, 1998;
p 421.
Pyun, S.-J . J . Chem. Soc., Perkin Trans.
1 1997, 797-798. (e)
Ikegashira, K.; Nishihara, Y.; Hirabayashi, K.; Mori, A.; Hiyama, T.
Chem. Commun. 1997, 1039-1040. (f) Ito, H.; Sensui, H.; Arimoto,
K.; Miura, K.; Hosomi, A. Chem. Lett. 1997, 639-640. (g) Ito, H.;
Arimoto, K.; Sensui, H.; Hosomi, A. Tetrahedron Lett. 1997, 38, 3977-
3980. (h) Nishihara, Y.; Ikegashira, K.; Mori, A.; Hiyama, T. Tetrahe-
dron Lett. 1998, 39, 4075-4078.
(2) (a) Yoshida, J .; Tamao, K.; Yamamoto, H.; Kakui, T.; Uchida,
T.; Kumada, M. Organometallics 1982, 1, 542-549. (b) Tamao, K.;
Kobayashi, K.; Ito, Y. Tetrahedron Lett. 1989, 30, 6051-6054. (c)
Hatanaka, Y.; Hiyama, T. J . Org. Chem. 1989, 54, 268-270. (d)
Hatanaka, Y.; Goda, K.; Hiyama, T. J . Organomet. Chem. 1994, 465,
97-100. (e) Mowery, M. E.; Deshong, P. J . Org. Chem. 1999, 64, 1684-
1688. (f) Denmark, S. E.; Wehrli, D. Org. Lett. 2000, 2, 565-568. (g)
Denmark, S. E.; Neuville, L. Org. Lett. 2000, 2, 3221-3224. (h)
Denmark, S. E.; Pan, W. Org. Lett. 2001, 3, 61-64. (i) Denmark, S.
E.; Wang, Z. Org. Lett. 2001, 3, 1073-1076. (j) Denmark, S. E.; Wang,
Z. J . Organomet. Chem. 2001, 624, 372-375. (k) Denmark, S. E.; Yang,
S.-M. Org. Lett. 2001, 3, 1749-1752. (l) Itami, K.; Nokami, T.; Yoshida,
J . J . Am. Chem. Soc. 2001, 123, 5600-5601. (m) Itami, K.; Nokami,
T.; Ishimura, Y.; Mitsudo, K.; Kamei, T.; Yoshida, J . J . Am. Chem.
Soc. 2001, 123, 11577-11585. (n) Denmark, S. E.; Sweis, R. F. J . Am.
Chem. Soc. 2001, 123, 6439-6440. (o) Denmark, S. E.; Yang, S.-M. J .
Am. Chem. Soc. 2002, 124, 2102-2103. (p) Hosoi, K.; Nozaki, K.;
Hiyama, T. Chem. Lett. 2002, 138-139.
(6) (a) Woodbury, R. P.; Rathke, M. W. J . Org. Chem. 1978, 43,
1947-1949. (b) Matsuda, I.; Murata, S.; Ishii, Y. J . Chem. Soc., Perkin
Trans. 1 1979, 26-30. (c) Isobe, M.; Kitamura, M.; Goto, T. Tetrahedron
Lett. 1979, 3465-3468. (d) Fleming, I.; Floyd, C. D. J . Chem. Soc.,
Perkin Trans. 1 1981, 969-976. (e) Takeda, T.; Naito, S.; Ando, K.;
Fujiwara, T. Bull. Chem. Soc. J pn. 1983, 56, 967-968. (f) Takeda, T.;
Ando, K.; Fujiwara, T. Chem. Lett. 1983, 1285-1288. (g) Brook, A. G.;
Chrusciel, J . J . Organometallics 1984, 3, 1317-1381. (h) Isobe, M.;
Ichikawa, Y.; Funabashi, Y.; Mio, S.; Goto, T. Tetrahedron 1986, 42,
2863-2872. (i) Tietze, L. F.; Geissler, H.; Gewert, J . A.; J akobi, U.
Synlett 1994, 511-512. (j) J ankowski, P.; Raubo, P.; Wicha, J . Synlett
1994, 985-992. (k) Shinokubo, H.; Miura, K.; Oshima, K.; Utimoto,
K. Tetrahedron 1996, 52, 503-514. (l) Smith, A. B., III; Boldi, A. M.
J . Am. Chem. Soc. 1997, 119, 6925-6926. (m) Smith, A. B., III; Pitram,
S. M. Org. Lett. 1999, 1, 2001-2004. (n) Bra¨uer, N.; Michel, T.;
Schaumann, E. Tetrahedron 1998, 54, 11481-11488. (o) Moser, W. H.
Tetrahedron 2001, 57, 2065-2084.
(3) (a) Denmark, S. E.; Choi, J . Y. J . Am. Chem. Soc. 1999, 121,
5821-5822. (b) Denmark, S. E.; Wehrli, D.; Choi, J . Y. Org. Lett. 2000,
2, 2491-2494. (c) Denmark, S. E.; Wang, Z. Synthesis 2000, 999-1003.
(4) Hatanaka, Y.; Hiyama, T. J . Org. Chem. 1988, 53, 918-920.
(7) (a) Kim, K. D.; Magriotis, P. A. Tetrahedron Lett. 1990, 31, 6137-
6140. (b) Lautens, M.; Delanghe, P. H. M.; Goh, J . B.; Zhang, C. H. J .
Org. Chem. 1995, 60, 4213-4227.
10.1021/jo025973r CCC: $22.00 © 2002 American Chemical Society
Published on Web 11/01/2002
8450
J . Org. Chem. 2002, 67, 8450-8456

2
1,4 Csp -to-O Silyl Migration
SCHEME 1
SCHEME 2
electrophiles other than proton.8 Moser and co-workers
reported the preparation of the aryllithium derivatives
2
by 1,4 Csp -to-O silyl migration of the arene chromium
complexes of o-(trimethylsilyl)benzyl alkoxides. In this
case, the resulting carbanions would be stabilized by the
electron-withdrawing capability of Cr(CO)3 coordinated
to the benzene ring.9
In the course of study on the preparation and synthetic
application of group 14 vinylmetal species,10 we found
that vinylsilanes possessing a 2-pyridylthio group at the
carbon R to the trimethylsilyl group reacted with allylic
halides in the presence of CuI-KF to produce the cross-
coupling products.10e We tentatively assume that the
reaction proceeds through transmetalation of silicon to
copper assisted by the intramolecular coordination of
nitrogen to silicon. On the basis of this idea, it is expected
that the hypercoordinated silicate 1 formed from the
copper alkoxide 2 of (Z)-γ-trimethylsilyl allylic alcohol 3
is converted into a Brook-type rearrangement product,
the vinylcopper species 4, which reacts with various
electrophiles (Scheme 1).
SCHEME 3
Here we describe the generation of a vinyl copper
2
species (or its equivalent) through Csp -to-O silyl migra-
tion of Z-3 promoted with copper tert-butoxide and their
cross-coupling reactions with allylic, vinylic, and aryl
halides.11
tistep transformation. Therefore, we first established the
stereoselective preparation of Z-3 by the reaction se-
quence similar to that employed for the synthesis of (Z)-
â-(tributylstannyl)-R,â-unsaturated ketones.10a
Resu lts a n d Discu ssion
Ster eoselective Syn th esis of γ-Tr im eth ylsilyl Al-
lylic Alcoh ols 3. To substantiate the above idea, the
Z-isomers of γ-trimethylsilyl allylic alcohols 3 are req-
uisite. Although various methods for the stereoselective
preparation of silyl alcohols 3 have been developed, most
of them can be employed only for the preparation of
E-isomers.12 Although Z-isomers of 3 are prepared via
The tin(IV) chloride-promoted reaction of R-trimeth-
ylsilyl thioacetals 5 with enol trimethylsilyl ethers 6 gave
the â-phenylthio ketones (7a , 91%; 7b, 75%; 7c, 90%).
The elimination of thiophenol from 7 with 1,8-diazabicyclo-
[5.4.0]undec-7-ene (DBU) afforded (Z)-â-(trimethylsilyl)-
R,â-unsaturated ketones Z-8 (Z-8a , 77%; Z-8b, 91%;
Z-8c, 49%) with complete stereoselectivity. The stereo-
chemical outcome of the elimination might be due to the
intramolecular coordination of the carbonyl oxygen to
silicon, which maintains the conformation favorable to
the formation of the Z-isomers. The reduction of the silyl
ketones 8 with lithium aluminum hydride gave the
secondary alcohols 3 (Z-3a , 86%; Z-3b, 73%; Z-3c, 63%)
(Scheme 2).
The primary alcohols E- and Z-3d and Z-3e were
prepared from acylsilanes (Scheme 3).13 The Peterson
olefination of acylsilanes 9 with lithium enolate of ethyl
trimethylsilyl acetate 10 produced (Z)-R,â-unsaturated
esters predominantly, and the pure Z-isomers were easily
separated by silica gel chromatography (Z-11a , 50%;
2
1,4 O-to-Csp silyl migration,7a the method requires mul-
(8) Spinazze´, P. G.; Keay, B. A. Tetrahedron Lett. 1989, 30, 1765-
1768.
(9) Moser, W. H.; Endsley, K. E.; Colyer, J . T. Org. Lett. 2000, 2,
717-719.
(10) (a) Takeda, T.; Sugi, S.; Nakayama, A.; Suzuki, Y.; Fujiwara,
T. Chem. Lett. 1992, 819-822. (b) Takeda, T.; Kabasawa, Y.; Fujiwara,
T. Tetrahedron 1995, 51, 2515-2524. (c) Takeda, T.; Matsunaga, K.;
Kabasawa, Y.; Fujiwara, T. Chem. Lett. 1995, 771-772. (d) Takeda,
T.; Matsunaga, K.; Uruga, T.; Takakura, M.; Fujiwara, T. Tetrahedron
Lett. 1997, 38, 2879-2882. (e) Takeda, T.; Uruga, T.; Gohroku, K.;
Fujiwara, T. Chem. Lett. 1999, 821-822.
(11) Preliminary communication: Taguchi, H.; Ghoroku, K.; Tadaki,
M.; Tsubouchi, A.; Takeda, T. Org. Lett. 2001, 3, 3811-3814.
(12) (a) Sato, F.; Watanabe, H.; Tanaka, Y.; Sato, M. J . Chem. Soc.,
Chem. Commun. 1982, 1126-1127. (b) Denmark, S. E.; J ones, T. K.
J . Org. Chem. 1982, 47, 4595-4597. (c) Murphy, P. J .; Spencer, J . L.;
Procter, G. Tetrahedron Lett. 1990, 31, 1051-1054. (d) Takai, K.;
Kataoka, Y.; Utimoto, K. J . Org. Chem. 1990, 55, 1707-1708. (e) Rane,
A. M.; Vaquer, J .; Colberg, J . C.; Soderquist, J . A. Tetrahedron Lett.
1995, 36, 987-990. (f) Takeuchi, R.; Nitta, S.; Watanabe, D. J . Org.
Chem. 1995, 60, 3045-3051.
(13) Fujiwara, T.; Sawabe, K.; Takeda, T. Tetrahedron 1997, 53,
8349-8370.
J . Org. Chem, Vol. 67, No. 24, 2002 8451

Taguchi et al.
TABLE 1. Ster eosp ecific Allyla tion of γ-Tr im eth ylsilyl
Allylic Alcoh ols 3 by Cop p er (I) ter t-Bu toxid e
SCHEME 4
SCHEME 5
E-11a , not produced; Z-11b, 71%; E-11b, 14%). Alterna-
tively the E-ester E-11b was stereoselectively prepared
by the Horner-Wadsworth-Emmons reaction of 9b
using diethyl ethoxycarbonylmethylphosphonate 12 (E,
54%; Z, 13%). The reduction of 11 with diisobutylalumi-
num hydride (DIBAL-H) produced the primary alcohols
3 (Z-3d , 62%; Z-3e, 88%; E-3e, 90%).
2
1,4 Csp -to-O Silyl Migr a tion of (Z)-γ-Tr im eth ylsi-
lyl Allylic Alcoh ols Z-3. As expected, the treatment of
the silyl alcohol Z-3a with copper(I) tert-butoxide (1.2
equiv), prepared in situ by the reaction of copper(I) iodide
with lithium tert-butoxide,14 in THF at room temperature
gave the Brook-type rearrangement product 13a (59%),
together with a small amount of the cyclic silyl ether 14a
(20%) (Scheme 4).
The above result implies the formation of the vinyl
2
copper species 4 as the initial product via Csp -to-O silyl
migration. The formation of cyclic silyl ether 14a , indeed,
indicates that the reaction proceeds through the forma-
tion of intermediary pentavalent silicon anion 1.
a
The configurations of the products were confirmed by NOE
b
Cop p er (I) ter t-Bu t oxid e-P r om ot ed Cr oss-Cou -
p lin g of (Z)-γ-Tr im eth ysilyl Allylic Alcoh ols 3 w ith
Allylic Ha lid es. The results of the copper(I) tert-butox-
experiments. A 1.2 equiv portion of copper(I) tert-butoxide was
used.
2
ide-promoted 1,4 Csp -to-O silyl migration of γ-trimeth-
shows the crucial importance of intramolecular coordina-
2
tion in 1,4 Csp -to-O silyl migration.
ylsilyl allylic alcohols 3 prompted us to investigate the
reaction of the intermediate organocopper species 4 with
allylic halides 15. The treatment of Z-3a with copper(I)
tert-butoxide (1.5 equiv) and methallyl chloride 15a (1.2
equiv) for 23 h at room temperature produced the tri-
methylsilyl ether of dienyl alcohol 16a in 92% yield. The
tetrabutylammonium fluoride-assisted hydrolysis of 16a
afforded the alcohol 17a in 80% overall yield (Scheme 5).
Under similar reaction conditions, the coupling reac-
tions of several γ-trimethylsilyl allylic alcohols 3 with
allylic halides 15 were performed using THF or DMF as
a solvent, and the allylation products 17 were obtained
with complete retention of configuration (Table 1). The
fact that the reaction of (E)-allylic alcohol E-3e with
methallyl chroride 15a was messy and no formation of
the corresponding dienyl alcohol 17i was observed clearly
P a lla d iu m -Ca ta lyzed Cr oss-Cou p lin g of Alk en yl-
2
cop p er In ter m ed ia tes Gen er a ted by 1,4 Csp -to-O
Silyl Migr a tion w ith Ar yl a n d Vin ylic Ha lid es. The
intermediary organocopper species is so reactive that it
is expected to be employed for various carbon-carbon
bond formations. We next examined the palladium-
catalyzed cross-coupling of γ-trimethylsilyl allylic alcohols
Z-3 with aryl halides 18. The successive treatment of
Z-3b with copper(I) tert-butoxide (1.2 equiv) and iodo-
benzene 18a (1.2 equiv) in the presence of Pd(PPh3)4 (3
mol %) at room temperature for 4 h produced the coupling
product 19d in 62% yield after hydrolysis with TBAF
(Scheme 6). Increasing the amount of 18a to 2.0 equiv
slightly increased the yield (68%). In both cases, the
arylation product 19d was produced as a mixture of
stereoisomers (Z:E ) 92:8). The formation of the E-isomer
was completely suppressed and 19d was obtained in
higher yield by the use of copper(I) chloride for the
(14) Tsuda, T.; Hashimoto, T.; Saegusa, T. J . Am. Chem. Soc. 1972,
94, 658-659.
8452 J . Org. Chem., Vol. 67, No. 24, 2002

2
1,4 Csp -to-O Silyl Migration
SCHEME 6
SCHEME 7
SCHEME 8
TABLE 2. P a lla d iu m (0)-Ca ta lyzed Cr oss-Cou p lin g of
(Z)-γ-Tr im eth ylsilyl Allylic Alcoh ols Z-3 w ith Ar yl
Ha lid es 18
SCHEME 9
reaction of Z-3b with iodobenzene 18a in the presence
of lithium tert-butoxide and Pd(PPh3)4 ended up with the
formation of the cyclic silyl ether 14b, and no formation
of 19b was observed (Scheme 7).
The vinylation of Z-3 was also accomplished using
vinylic bromides 20 in a manner similar to that employed
for the arylation of Z-3. The treatment of Z-3 with copper-
(I) tert-butoxide prepared from copper(I) chloride and
lithium tert-butoxide and then 20 in the presence of a
catalytic amount of Pd(PPh3)4 (3 mol %) gave the stere-
ochemically defined conjugated dienyl silyl ether 21. The
subsequent hydrolysis of 21 with TBAF produced the
dienyl alcohols 22 (Scheme 8, Table 3).
The palladium-catalyzed cross-coupling reactions of
vinylsilanes possessing an electronegative ligand and the
reactions accelerated by a fluoride ion are believed to
involve transmetalation and reductive elimination of
palladium. The coupling reaction of trimethylvinylsilane
with aryl halides under ordinary Heck conditions was
investigated, and its regiochemistry was found to be
opposite to the above reactions of activated vinylsilanes,
indicating that it proceeds via 1,2-addition of arylpalla-
dium species to the double bond.15 A plausible pathway
for the palladium(0)-catalyzed cross-coupling reaction of
γ-silyl allylic alcohols Z-3 is illustrated in Scheme 9.
a
The configurations of the products were confirmed by NOE
experiments.
preparation of copper(I) tert-butoxide (entry 4, Table 2).
Using the optimized conditions, the reactions of several
γ-silyl allylic alcohols Z-3 with aryl iodides 18 were
performed and the arylation products were obtained in
good yields with complete retention of configuration.
It was confirmed that no cross-coupling product was
produced in the absence of the palladium catalyst. The
J . Org. Chem, Vol. 67, No. 24, 2002 8453

Taguchi et al.
TABLE 3. P a lla d iu m (0)-Ca ta lyzed Cr oss-Cou p lin g of
(Z)-γ-Tr im eth ylsilyl Allylic Alcoh ols Z-3 w ith Vin ylic
Br om id es 20
tilled from calcium hydride. Preparative thin-layer chroma-
tography (PTLC) was carried out using Wakogel B-5F. Column
chromatography was performed on Merck Si 60 or Merck
aluminum oxide 90 deactivated by addition of water (5 wt %).
1H (500 MHz) and 13C (125 MHz) NMR spectra were recorded
in CDCl3 and chemical shifts (δ) are quoted in parts per million
1
from tetramethylsilane for H and CDCl3 for 13C spectroscopy.
IR absorptions are reported in cm-1
.
P r ep a r a tion of (Z)-2-[3-P h en yl-1-(tr im eth ylsilyl)p r o-
p a n -1-ylid en e]cycloh exa n on e (Z-8a ). To a CH2Cl2 (15 mL)
solution of 3-phenyl-1,1-bis(phenylthio)-1-(trimethylsilyl)pro-
pane (5a ) (12.3 g, 30 mmol) was added a CH2Cl2 (15 mL)
solution of 1-(trimethylsiloxy)cyclohexene 6a (6.6 g, 30 mmol)
at room temperature under argon. After cooling to -78 °C, a
CH2Cl2 solution of SnCl4 (1.5 M, 20 mL, 30 mmol) was added
and the mixture was stirred for 12 h. The reaction was
quenched by addition of water. After warming up to room
temperature, organic materials were extracted with CH2Cl2,
washed with 1 M NaOH and then water, and dried over Na2-
SO4. The solvent was removed under reduced pressure and
the residue was chromatographed on silica gel (hexane/AcOEt
) 98/2) to give 2-[3-phenyl-1-(phenylthio)-1-(trimethylsilyl)-
propyl]cyclohexanone (7a ) (10.8 g, 91%). 7a : IR (neat) 3087,
3064, 3032, 3003, 2968, 2904, 2870, 1716, 1604, 1583, 1496,
1473, 1456, 1439, 1410, 1348, 1311, 1263, 1252, 1207, 1128,
1097, 1080, 1066, 1026, 1003, 885, 854, 793, 752, 702, 658
1
cm-1; H NMR δ 0.26 (s, 3.6H), 0.27 (s, 5.4H), 1.44-1.55 (m,
1H), 1.60-1.89 (m, 3H), 1.93-2.09 (m, 2.6H), 2.18-2.37 (m,
2H), 2.41-2.51 (m, 1.4H), 2.64 (dd, J ) 13.1, 4.3 Hz, 0.6 H),
2.68-2.78 (m, 2H), 2.86 (dt, J ) 13.1, 4.3 Hz, 0.4H), 7.05-
7.07 (m, 1H), 7.13-7.18 (m, 2H), 7.22-7.36 (m, 5H), 7.56-
7.59 (m, 2H); 13C NMR δ 1.23, 1.41, 25.8, 26.1, 28.3, 28.4, 30.8,
31.3, 32.0, 32.7, 36.7, 38.7, 43.3, 43.4, 45.5, 46.5, 56.9, 58.7,
125.8, 128.2, 128.31, 128.34, 128.5, 128.57, 128.61, 128.7,
132.2, 132.7, 137.0, 137.3, 142.2, 142.5, 211.9, 212.2.
a
The configurations of the products were confirmed by NOE
b
experiments. The product was isolated without hydrolysis.
The ketone 7a (4.52 g, 11.4 mmol) and DBU (3.4 mL, 22.9
mmol) were dissolved in THF (11 mL) at 0 °C, and the mixture
was stirred for 5 days. The reaction was quenched by addition
of water, and the organic materials were extract with ether.
The combined extracts were washed with 1 M NaOH and
water, dried over Na2SO4, and then concentrated under
reduced pressure. The residue was purified by column chro-
matography (silica gel, hexane/AcOEt ) 98/2) to afford Z-8a
(2.52 g, 77%). Z-8a : IR (neat) 3062, 3026, 2945, 1676, 1603,
1545, 1495, 1454, 1433, 1412, 1335, 1319, 1279, 1244, 1144,
1084, 1068, 914, 843, 768, 748, 698, 671 cm-1; 1H NMR δ 0.18
(s, 9H), 1.69-1.74 (m, 2H), 1.83-1.89 (m, 2H), 2.44 (t, J ) 6.7
Hz, 2H), 2.52 (t, J ) 6.7 Hz, 2H), 2.55 (bs, 4H), 7.18-7.22 (m,
3H), 7.26-7.31 (m, 2H); 13C NMR δ 0.71, 24.1, 24.4, 29.4, 34.6,
35.2, 41.3, 126.0, 128.3, 128.4, 141.7, 146.6, 153.2, 203.5. Anal.
Calcd for C18H26OSi: C, 75.46; H, 9.15. Found: C, 75.43; H,
9.39.
Transmetalation of the vinylcopper species 4 with the
organopalladium species R4Pd(II)X, followed by reductive
elimination, affords the cross-coupling product.
Con clu sion s
We have developed the copper(I) tert-butoxide-promot-
2
ed 1,4 Csp -to-O silyl migration of (Z)-γ-trimethylsilyl
allylic alcohols. The intermediates, probably vinylcopper
species, react with organic halides in the absence or
presence of a palladium(0) catalyst to afford the cross-
coupling products with complete retention of configura-
tion. These reactions, together with the stereoselective
methods for the preparation of the starting materials
provide a useful synthesis of geometrically well-defined
tri- and tetrasubstituted olefins. It should be noted that
the present study first demonstrated the synthetic utility
of the Brook-type rearrangement via copper(I) alkoxide.
In a similar manner, the â-(trimethylsilyl)-R,â-unsaturated
ketones Z-8b and Z-8c were obtained.
P r ep a r a tion of (Z)-2-[3-P h en yl-1-(tr im eth ylsilyl)p r o-
p a n -1-ylid en e]cycloh exa n ol (Z-3a ). To a THF (8.8 mL)
suspension of lithium aluminum hydride (334 mg, 8.8 mmol)
was added dropwise a THF (8.8 mL) solution of the ketone
Z-8a (2.52 g, 8.8 mmol) at -78 °C under argon. After stirring
for 5 h at -78 °C, the reaction was quenched by dropwise
addition of a saturated aqueous solution of Na2SO4. Insoluble
materials were filtered off through Celite and washed with
ether. The filtrate was condensed under reduced pressure and
the residue was recrystalized from hexane to give Z-3a (2.18
g, 86%). Z-3a : mp 72.0-72.5 °C; IR (KBr) 3357, 3084, 3064,
3026, 3001, 2939, 2852, 1603, 1493, 1468, 1454, 1282, 1252,
1086, 997, 984, 883, 862, 835, 760, 750, 702, 687 cm-1; 1H NMR
δ 0.21 (s, 9H), 1.12-1.21 (m, 1H), 1.29 (bs, 1H), 1.48-1.55 (m,
2H), 1.78-1.86 (m, 2H), 1.94-1.98 (b, 1H), 2.10 (dt, J ) 4.0,
Exp er im en ta l Section
Gen er a l Meth od s. R-Trimethylsilyl thioacetals were pre-
pared according to the method reported by Reich et al.16
Acylsilanes were synthesized from dithianes.16 Tetrahydrofu-
ran (THF) was distilled from sodium and benzophenone.
Dimethylformamide (DMF) was distilled from calcium hydride
under reduced pressure. Dichloromethane (CH2Cl2) was dis-
(15) (a) Daves, G. D., J r.; Hallberg, A. Chem. Rev. 1989, 89, 1433-
1445. (b) Hallberg, A.; Westerlund, C. Chem. Lett. 1982, 1993-1994.
(c) Karabelas, K.; Hallberg, A. J . Org. Chem. 1989, 54, 1773-1776.
(d) Alvisi, D.; Blart, E.; Bonini, B. F.; Mazzanti, G.; Ricci, A.; Zani, P.
J . Org. Chem. 1996, 61, 7139-7146.
(16) Reich, H. J .; Holtan, R. C.; Bolm, C. J . Am. Chem. Soc. 1990,
112, 5609-5617.
8454 J . Org. Chem., Vol. 67, No. 24, 2002

2
1,4 Csp -to-O Silyl Migration
13.7 Hz, 1H), 2.34-2.57 (m, 5H), 4.62 (br, 1H), 7.17-7.20 (m,
3H), 7.26-7.29 (m, 2H); 13C NMR δ 1.25, 20.3, 25.4, 27.8, 33.2,
33.9, 37.1, 71.4, 125.8, 128.3, 128.4, 133.6, 142.1, 152.3. Anal.
Calcd for C18H28OSi: C, 74.94; H, 9.78. Found: C, 75.17; H,
9.60.
were placed in a flask and cooled to 0 °C. Lithium tert-butoxide
(1 M in THF, 0.36 mL, 0.36 mmol) was added under argon
and the mixture was stirred for 20 min at room temperature.
A THF (1.5 mL) solution of Z-3a (86 mg, 0.30 mmol) was added
to the mixture. After stirring for 24 h at room temperature,
the reaction was quenched by addition of 3.5% NH3 aqueous
solution. The organic materials were extracted with ether,
dried over Na2SO4, and concentrated. The residue was purified
by column chromatography (aluminum oxide, hexane/EtOAc
) 95/5) to give (E)-1-(3-phenylpropan-1-ylidene)-2-(trimethyl-
siloxy)cyclohexane (13a ) (51 mg, 59%) and 8,8-dimethyl-9-
phenethyl-7-oxa-8-silabicyclo[4.3.0]non-9-ene 14a (16 mg, 20%).
13a : IR (neat) 3087, 3066, 3032, 2933, 2862, 1496, 1456, 1252,
1149, 1132, 1105, 1082, 1039, 1018, 926, 908, 839, 748, 698
In a similar manner, the γ-trimethylsilyl allylic alcohols
Z-3b and Z-3c were obtained.
P r ep a r a tion of Eth yl (Z)-3-P h en yl-3-(tr im eth ylsilyl)-
p r op -2-en oa te (Z-11a ). To a THF (10 mL) solution of tet-
ramethyldisilazane (1.3 mL, 6.0 mmol) was added butyllithium
(1.6 M in hexane, 3.8 mL, 6.0 mmol) at 0 °C under argon. After
stirring for 20 min at 0 °C, a THF (7.5 mL) solution of ethyl
(trimethylsilyl)acetate (10) (962 mg, 6.0 mmol) and a THF (7.5
mL) solution of 9a (892 mg, 5.0 mmol) were successively added
at -78 °C over an interval of 15 min. The reaction mixture
was warmed to 0 °C and stirred for 4 h. The reaction was
quenched by addition of a saturated aqueous solution of
NaHCO3, and organic materials were extracted with ether. The
organic layer was washed with water, dried over Na2SO4, and
concentrated. The residue was chromatographed on silica gel
(hexane/AcOEt ) 99/1) to give the Z isomer Z-11a (552 mg,
50%). Z-11a : IR (neat) 3080, 3060, 3028, 2987, 2958, 2904,
1726, 1593, 1491, 1442, 1367, 1325, 1250, 1232, 1190, 1097,
1
cm-1; H NMR δ 0.09 (s, 9H), 1.19-1.28 (m, 1H), 1.35-1.49
(m, 3H), 1.70-1.82 (m, 3H), 2.30-2.43 (m, 3H), 2.65 (t, J )
7.8 Hz, 2H), 3.98 (dd, J ) 7.9, 3.1 Hz, 1H), 5.40 (t, J ) 7.0 Hz,
1H), 7.15-7.19 (m, 3H), 7.25-7.28 (m, 2H); 13C NMR δ 0.08,
23.5, 26.5, 27.2, 28.8, 36.3, 37.5, 73.9, 119.2, 125.6, 128.2, 128.5,
141.5, 142.3. Anal. Calcd for C18H28OSi: C, 74.93; H, 9.78.
Found: C, 74.85; H, 9.80. 14a : IR (neat) 3086, 3062, 3028,
2933, 2856, 1616, 1604, 1496, 1454, 1335, 1252, 1078, 953, 881,
1
854, 827, 783, 748, 698 cm-1; H NMR δ 0.23 (s, 3H), 0.26 (s,
1
1036, 893, 850, 773, 752, 702 cm-1; H NMR δ 0.19 (s, 9H),
3H), 0.87-0.98 (m, 1H), 1.06-1.16 (m, 1H), 1.39 (m, 1H), 1.60-
1.75 (m, 3H), 2.20-2.25 (m, 1H), 2.46-2.50 (m, 2H), 2.58-
2.69 (m, 3H), 4.34 (dd, J ) 11.3, 5.2 Hz, 1H), 7.16-7.20 (m,
3H), 7.23-7.30 (m, 2H); 13C NMR δ 0.76, 1.74, 24.3, 26.7, 27.1,
28.8, 36.7, 38.2, 82.7, 125.8, 128.2, 128.4, 128.7, 142.0, 156.3.
Anal. Calcd for C17H24OSi: C, 74.94; H, 8.88. Found: C, 74.62;
H, 9.12.
1.32 (t, J ) 7.0 Hz, 3H), 4.23 (q, J ) 7.0 Hz, 2H), 6.34 (s, 1H),
7.03-7.05 (m, 2H), 7.22-7.26 (m, 1H), 7.28-7.32 (m, 2H); 13
C
NMR δ -0.02, 14.3, 60.4, 126.2, 126.6, 127.9, 132.9, 145.3,
165.7, 166.8. Anal. Calcd for C14H20O2Si: C, 67.70; H, 8.11.
Found: C, 67.38; H, 8.24.
Similarly, the R,â-unsaturated ester Z-11b was obtained by
the reaction of 9b with 10.
Allyla tion of Z-3a w ith Meth a llyl Ch lor id e (15a ). CuI
(63 mg, 0.33 mmol) and DMF (1 mL) were placed in a flask
and cooled to 0 °C. Lithium tert-butoxide (1 M in THF, 0.36
mL, 0.36 mmol) was added under argon and the mixture was
stirred for 20 min at room temperature. A DMF (1 mL) solution
of 3a (86 mg, 0.30 mmol) and a DMF (1 mL) solution of 15a
(33 mg, 0.36 mmol) were successively added to the mixture.
After stirring for 2 h at room temperature, the reaction was
quenched by addition of 3.5% NH3 aqueous solution. The
organic materials were extracted with ether, dried over Na2-
SO4, and concentrated. The residue was dissolved in THF (3
mL), and TBAF (1 M in THF, 0.3 mL, 0.3 mmol) was added to
the solution. The mixture was stirred for 2 h at room
temperature and diluted with water (15 mL). The organic
materials were extracted with AcOEt, washed with 1 M HCl
and water, and dried over Na2SO4. The solvent was removed
under reduced pressure. The residue was purified by PTLC
(hexane/AcOEt ) 4/1) to afford (Z)-2-(2-methyl-6-phenylhex-
1-en-4-ylidene)cyclohexanol (17a ) (65 mg, 80%). 17a : IR (neat)
3369, 3064, 3026, 2931, 2854, 1645, 1603, 1496, 1452, 1373,
1350, 1335, 1255, 1227, 1176, 1142, 1093, 1074, 1045, 1030,
P r ep a r a tion of Eth yl (E)-5-P h en yl-3-(tr im eth ylsilyl)-
p en t-2-en oa te (E-11b). To a benzene (1 mL) suspension of
NaH (55 wt % in mineral oil, 44 mg, 1.0 mmol) was added a
benzene (1 mL) solution of diethyl ethoxycarbonylmethylphos-
phonate (224 mg, 1.0 mmol) under argon. The mixture was
stirred for 1 h at room temperature. The acylsilane 9b (206
mg, 1.0 mmol) in benzene (1 mL) was added to the reaction
mixture. After stirring for 2 h at 60 °C, hexane (20 mL) was
added to the mixture, and insoluble materials were separated
by decantation with hexane. The solvent was removed under
reduced pressure. The residue was purified by PTLC (hexane/
AcOEt ) 98/2) to give E-11b (150 mg, 54%) and Z-11b (35
mg, 13%). E-11b: IR (neat) 3087, 3066, 3032, 2962, 2933, 2906,
2870, 1716, 1604, 1496, 1456, 1367, 1342, 1252, 1196, 1167,
1090, 1059, 1036, 843, 752, 700 cm-1; 1H NMR δ 0.17 (s, 9H),
1.32 (t, J ) 7.2 Hz, 3H), 2.67-2.72 (m, 2H), 2.91-2.96 (m, 2H),
4.23 (q, J ) 7.2 Hz, 2H), 6.10 (s, 1H), 7.17-7.21 (m, 1H), 7.27-
7.31 (m, 4H); 13C NMR δ -1.9, 14.3, 33.7, 35.9, 59.8, 125.8,
127.1, 128.3, 128.4, 142.2, 165.2, 165.4. Anal. Calcd for
C
16H24O2Si: C, 69.52; H, 8.75. Found: C, 69.41; H, 8.96.
1
987, 964, 889, 748, 698 cm-1; H NMR δ 1.09-1.20 (m, 1H),
P r ep a r a tion of (Z)-5-P h en yl-3-(tr im eth ylsilyl)p en t-2-
1.32 (bs, 1H), 1.40-1.53 (m, 2H), 1.71 (s, 3H), 1.70-1.82 (m,
2H), 1.89-1.95 (m, 1H), 2.11 (dt, J ) 13.7, 3.4 Hz, 1H), 2.25-
2.37 (m, 2H), 2.45 (d, J ) 13.7 Hz, 1H), 2.63 (t, J ) 8.2 Hz,
2H), 2.75 (d, J ) 15.9 Hz, 1H), 2.87 (d, J ) 15.9 Hz, 1H), 4.68
(s, 2H), 4.77 (s, 1H), 7.16-7.20 (m, 3H), 7.24-7.28 (m, 2H);
13C NMR δ 20.1, 22.9, 25.1, 27.4, 33.7, 34.4, 35.2, 39.8, 66.7,
110.8, 125.8, 128.2, 128.3, 130.0, 136.8, 142.1, 144.4. Anal.
Calcd for C19H26O: C, 84.39; H, 9.69. Found: C, 84.16; H,
10.15.
en -1-ol (Z-3e). To a mixture of DIBAL-H (1 M in hexane, 12.3
mL, 12.3 mmol) and CH2Cl2 (11.2 mL) was added a CH2Cl2 (7
mL) solution of Z-11a (1.55 g, 5.6 mmol) under argon. After
stirring for 2 h at room temperature, the reaction was
quenched by dropwise addition of a saturated aqueous solution
of NaHCO3. Insoluble materials were filtered off and washed
with ether. The filtrate was concentrated and the residue was
purified by column chromatography (silica gel, hexane/AcOEt
) 4/1) to afford Z-3e (1.16 g, 88%). Z-3e: IR (neat) 3462, 3087,
3066, 3032, 2972, 1604, 1496, 1456, 1410, 1252, 1074, 1003,
839, 748, 698, 660 cm-1; 1H NMR δ 0.20 (s, 9H), 1.19 (bs, 1H),
2.37-2.41 (m, 2H), 2.64-2.67 (m, 2H), 4.20 (d, J ) 7.0 Hz,
2H), 6.13 (tt, J ) 6.9, 1.1 Hz, 1H), 7.16-7.20 (m, 3H), 7.26-
7.30 (m, 2H); 13C NMR δ 0.35, 36.9, 39.9, 62.2, 125.8, 128.3,
128.5, 140.7, 142.1, 143.7. Anal. Calcd for C14H22OSi: C, 71.73;
H, 9.46. Found: C, 71.38; H, 9.59.
The silyl ether (Z)-1-[(2-methyl-6-phenylhex-1-en-4-ylidene)]-
2-(trimethylsiloxy)cyclohexane (16a ) (95 mg, 92%) was ob-
tained when the product was purified, before hydrolysis, by
column chromatography (aluminum oxide, hexane/AcOEt )
95/5). 16a : IR (neat) 3064, 3028, 2933, 2852, 1651, 1604, 1496,
1454, 1373, 1360, 1340, 1248, 1176, 1147, 1093, 1074, 1047,
1
1018, 901, 870, 839, 748, 698 cm-1; H NMR δ 0.09 (s, 9H),
The γ-trimethylsilyl allylic alcohols Z-3d and E-3e were
prepared in a similar manner.
Th e Br ook -typ e Rea r r a n gem en t of Z-3a w ith Cop p er
ter t-Bu toxid e. CuI (63 mg, 0.33 mmol) and THF (1.5 mL)
1.13-1.23 (m, 1H), 1.34-1.44 (m, 2H), 1.70 (s, 3H), 1.76-1.89
(m, 3H), 2.14-2.26 (m, 2H), 2.34-2.41 (m, 2H), 2.55-2.65 (m,
3H), 2.99 (d, J ) 15.6 Hz, 1H), 4.67 (s, 1H), 4.69 (s, 1H), 4.77
(s, 1H), 7.15-7.18 (m, 3H), 7.25-7.28 (m, 2H); 13C NMR δ 0.49,
J . Org. Chem, Vol. 67, No. 24, 2002 8455

Taguchi et al.
20.3, 22.8, 25.4, 28.2, 34.3, 35.2, 35.8, 40.1, 67.2, 111.2, 125.7,
127.0, 128.25, 128.30, 138.3, 142.5, 144.1. Anal. Calcd for
1452, 1335, 1255, 1142, 1101, 1070, 1030, 1014, 980, 914, 768,
1
748, 698 cm-1; H NMR δ 1.11-1.25 (m, 2H), 1.38-1.52 (m,
C
22H34OSi: C, 77.13; H, 10.00. Found: C, 77.20; H, 10.27.
2H), 1.72-1.82 (m, 3H), 2.21(dt, J ) 3.9, 13.6 Hz, 1H), 2.46-
2.71 (m, 5H), 4.29 (s, 1H), 7.12-7.18 (m, 5H), 7.23-7.28 (m,
3H), 7.32-7.35 (m, 2H); 13C NMR δ; 20.1, 25.1, 27.5, 34.1, 34.4,
36.0, 68.0, 125.8, 126.4, 128.1, 128.2, 128.4, 128.7, 135.0, 137.1,
141.9, 142.4. Anal. Calcd for C21H24O: C, 86.26; H, 8.27.
Found: C, 86.02; H, 8.48.
The arylation and vinylation products 19b-h , 21a -c, and
22a ,b were also obtained by similar reactions of Z-3 with the
corresponding aryl and vinylic halides 18 and 20. The silyl
ethers 21a -c were isolated before hydrolysis.
In a similar manner, the dienyl alcohols 17b-h were
obtained.
P a lla d iu m -Ca ta lyzed Cr oss-Cou p lin g of Z-3a w ith
Iod oben zen e (18a ). To a DMF (1 mL) suspension of CuCl
(33 mg, 0.33 mmol) and Pd(PPh3)4 (10 mg, 9 µmol) was added
lithium tert-butoxide (1 M in THF, 0.36 mL, 0.36 mmol) under
argon at 0 °C. After stirring for 20 min at room temperature,
a DMF (1 mL) solution of Z-3a (86 mg, 0.30 mmol) and a DMF
(1 mL) solution of 18a (122 mg, 0.60 mmol) were successively
added to the mixture. After stirring for 2 h at room temper-
ature, the reaction was quenched by addition of 3.5% NH3
aqueous solution (15 mL). The organic materials were ex-
tracted with ether, dried over Na2SO4, and concentrated. The
residue was dissolved in THF (3 mL), and TBAF (1 M in THF,
0.3 mL, 0.3 mmol) was added to the solution. The mixture was
stirred for 2 h at room temperature and then diluted with
water (15 mL). The organic materials were extracted with
AcOEt, washed with 1 M HCl and water, and dried over Na2-
SO4. The solvent was removed under reduced pressure. The
residue was purified by PTLC (hexane/AcOEt ) 4/1) to afford
(Z)-2-(1,3-diphenylpropan-1-ylidene)cyclohexanol 19a (68 mg,
78%). 19a : IR (neat) 3394, 3059, 3024, 2929, 2854, 1601, 1491,
Ack n ow led gm en t. This work was partially sup-
ported by a Grant-in-Aid for Scientific Research on
Priority Area (A) “Exploitation of Multi-Element Cyclic
Molecules” (No. 14044022) from the Ministry of Educa-
tion, Culture, Sports, Science and Technology, J apan.
Su p p or tin g In for m a tion Ava ila ble: Characterization
data for compounds Z-3b-d , E-3e, 7b,c, Z-8b, Z-8c, Z-11b,
14b, 17b-h , 19b-h , 21a -c, and 22a ,b. This material is
available free of charge via the Internet at http://pubs.acs.org.
J O025973R
8456 J . Org. Chem., Vol. 67, No. 24, 2002