Intramolecular cyclization of tert-butyldiphenylallylsilane units and carbonyl groups: Allylsilane terminated cyclization versus the ene reaction

Article abstract of DOI:10.1021/jo0158736

tert-Butyldiphenylsilylcopper reacts with allene to give an allylsilane-vinylcopper intermediate which upon treatment with α,β-unsaturated ketones leads to allylsilane containing ketones resulting from conjugate addition. These oxoallylsilanes bearing the bulky tert-butyldiphenylsilyl group undergo highly selective intramolecular cyclizations when treated with Lewis acid affording unsaturated cyclopentanols. Two reactivity patterns are observed: allylsilane terminated cyclization involving elimination of silicon or an ene reaction without losing the silyl group. The pathway depends on the ability of a hydrogen β to the carbonyl to be removed in an ene-type process, α,β-Unsaturated acid chlorides lead to silylated cyclopentenones.

Full text of DOI:10.1021/jo0158736

J . Org. Chem. 2001, 66, 7723-7728
7723
In tr a m olecu la r Cycliza tion of ter t-Bu tyld ip h en yla llylsila n e Un its
a n d Ca r bon yl Gr ou p s: Allylsila n e Ter m in a ted Cycliza tion ver su s
th e En e Rea ction
Asuncio´n Barbero, Pilar Castren˜o, Carlos Garc´ıa, and Francisco J . Pulido*
Departamento de Quı´mica Orga´nica, Universidad de Valladolid, Valladolid 47011, Spain
pulido@qo.uva.es
Received J une 27, 2001
tert-Butyldiphenylsilylcopper reacts with allene to give an allylsilane-vinylcopper intermediate which
upon treatment with R,â-unsaturated ketones leads to allylsilane containing ketones resulting from
conjugate addition. These oxoallylsilanes bearing the bulky tert-butyldiphenylsilyl group undergo
highly selective intramolecular cyclizations when treated with Lewis acid affording unsaturated
cyclopentanols. Two reactivity patterns are observed: allylsilane terminated cyclization involving
elimination of silicon or an ene reaction without losing the silyl group. The pathway depends on
the ability of a hydrogen â to the carbonyl to be removed in an ene-type process. R,â-Unsaturated
acid chlorides lead to silylated cyclopentenones.
The metallocupration of allenes and acetylenes is a
powerful and synthetically useful reaction which has
attracted considerable attention in the scientific com-
munity.1,2 For the past 10 years,3,4 we have been involved
in the study of the silyl- and stannylcupration of allenes
and acetylenes. These metallometalation reactions in-
volve the addition of copper to one end of a multiple bond
and of a silyl or stannyl group to the other, leading to a
useful method for the synthesis of silicon or tin containing
allyl- and vinylorganocuprates. The silylcupration of
allenes is a reversible reaction whose regiochemistry
depends on several factors such as temperature, structure
of the allene, nature of the silyl group, and nature of the
copper species.5 The different regioselectivity found in the
reaction of allene with phenyldimethylsilylcuprate6 and
tert-butyldiphenylsilylcuprate7 (formally higher-order cu-
prates) provides a useful route for the selective synthesis
of phenyldimethylvinylsilanes and tert-butyldiphenyl-
allylsilanes, respectively.
The use of phenyldimethylsilylcopper8 1 as a silylating
agent instead of the corresponding cuprate causes a
dramatic change upon the regiochemistry of the silyl-
cupration of allenes. Thus, the reaction of silylcopper
species 1 with allene8 is a highly regioselective method
to obtain functionalized allylsilanes through a vinyl-
copper-allylsilane intermediate which readily reacts with
different electrophiles (Scheme 1).
(1) Stoichiometric metallometalations: (a) Sharma, S.; Oehlschlager,
A. C. J . Org. Chem. 1991, 56, 770. (b) Singer, R. D.; Hutzinger, M. W.;
Oehlschlager, A. C. J . Org. Chem. 1991, 56, 4933. (c) Singer, R. D.;
Hutzinger, M. W.; Oehlschlager, A. C. J . Am. Chem. Soc. 1990, 112,
9397. (d) Piers, E.; Gavai, A. V. J . Org. Chem. 1990, 55, 2374, 2380.
(e) Piers, E.; Chong, J . M. Can. J . Chem. 1988, 66, 1425. (f) Cox, S. D.;
Wudl, F. Organometallics 1983, 2, 184. (g) Lipshutz, B. H.; Sharma,
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Marino, J . P.; Edmonds, M. V. M.; Stengel, P. J .; Oliveira, A. R. M.;
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Beaudet, I.; Parrain, J . L.; Quintard, J . P. Tetrahedron Lett. 1991, 32,
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See also ref 1c and citations therein.
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C. Tetrahedron Lett. 1986, 27, 6161. (b) Sharma, S.; Oehlschlager, A.
C. Tetrahedron Lett. 1988, 29, 261. (c) Nozaki, K.; Wakamatsu, K.;
Nonaka, T.; Tu¨ckmantel, W.; Oshima, K.; Utimoto, K. Tetrahedron Lett.
1986, 27, 2007. (d) Nonaka, T.; Okuda, Y.; Matsubara, S.; Oshima, K.;
Utimoto, K.; Nozaki, H. J . Org. Chem. 1986, 51, 4716. (e) Mitchell, T.
N.; Wickenkamp, R.; Amaria, A.; Dicke, R.; Schneider, U. J . Org. Chem.
1987, 52, 4868. (f) Mitchell, T. N. J . Organomet. Chem. 1992, 437, 127.
(g) See also ref 1c and citations therein.
(3) SiCu of allenes and acetylenes: (a) Cuadrado, P.; Gonza´lez, A.
M.; Pulido, F. J .; Fleming, I. Tetrahedron Lett. 1988, 29, 1825. (b)
Barbero, A.; Cuadrado, P.; Gonza´lez, A. M.; Pulido, F. J .; Fleming, I.;
Sa´nchez, A. J . Chem. Soc., Perkin Trans. 1 1995, 1525. (c) Blanco, F.
J .; Cuadrado, P.; Gonza´lez, A. M.; Pulido, F. J . Synthesis 1996, 42. (d)
Barbero, A.; Blanco, Y.; Garc´ıa, C.; Pulido, F. J . Synthesis 2000, 1223.
(e) Barbero, A.; Garc´ıa, C.; Pulido, F. J . Synlett 2001, 824.
(4) SnCu of allenes and acetylenes: (a) Barbero, A.; Cuadrado, P.;
Gonza´lez, A. M.; Pulido, F. J .; Fleming, I. J . Chem. Soc., Chem.
Commun. 1990, 1030. (b) Barbero, A.; Cuadrado, P.; Gonza´lez, A. M.;
Pulido, F. J .; Fleming, I. J . Chem. Soc., Perkin Trans. 1 1992, 327. (c)
Barbero, A.; Cuadrado, P.; Gonza´lez, A. M.; Pulido, F. J .; Fleming, I.
J . Chem. Res., Synop. 1990, 297, 291. (d) See also ref 1c. (e) Barbero,
A.; Cuadrado, P.; Gonza´lez, A. M.; Pulido, F. J .; Fleming, I. J . Chem.
Soc., Chem. Commun. 1992, 351. (f) Barbero, A.; Cuadrado, P.;
Gonza´lez, A. M.; Pulido, F. J .; Rubio, R.; Fleming, I. J . Chem. Soc.,
Perkin Trans. 1 1993, 1657. (g) Barbero, A.; Cuadrado, P.; Garc´ıa, C.;
Rinco´n, J . A.; Pulido, F. J . J . Org. Chem. 1998, 63, 7531. (h) Barbero,
A.; Pulido, F. J .; Rinco´n, J . A.; Cuadrado, P.; Galisteo, D.; Mart´ınez-
Garc´ıa, H. Angew. Chem., Int. Ed. 2001, 40, 2101.
Interestingly enough, the use of R,â-unsaturated acid
chlorides, aldehydes, and ketones affords allylsilanes
containing divinyl ketones and oxoallylsilanes,9,10a which
are valuable intermediates in the synthesis of methyl-
enecyclopentanols and methylenecyclopentanones. Cy-
clopentane ring formation results from a stereocontrolled
silicon-assisted intramolecular cyclization upon treat-
(5) (a) Barbero, A.; Pulido, F. J . Recent Res. Dev. Synth. Org. Chem.
1999, 2, 1.
(6) (a) Fleming, I.; Pulido, F. J . J . Chem. Soc., Chem. Commun. 1986,
1010. (b) Cuadrado, P.; Gonza´lez, A. M.; Pulido, F. J .; Fleming, I.;
Rowley, M. Tetrahedron 1989, 45, 413.
(7) Barbero, A.; Cuadrado, P.; Gonza´lez, A. M.; Pulido, F. J .;
Fleming, I. J . Chem. Soc., Perkin Trans. 1 1991, 2811.
(8) Blanco, F. J .; Cuadrado, P.; Gonza´lez, A. M.; Pulido, F. J .;
Fleming, I. Tetrahedron Lett. 1994, 35, 8881.
(9) Barbero, A.; Garc´ıa, C.; Pulido, F. J . Tetrahedron Lett. 1999, 40,
6652.
(10) (a) Barbero, A.; Garc´ıa, C.; Pulido, F. J . Tetrahedron 2000, 56,
2739. (b) Trost, B. M.; Coppola, B. P. J . Am. Chem. Soc. 1982, 104,
6879.
10.1021/jo0158736 CCC: $20.00 © 2001 American Chemical Society
Published on Web 10/24/2001

7724 J . Org. Chem., Vol. 66, No. 23, 2001
Barbero et al.
Sch em e 1
Sch em e 3
Ta ble 1. Rea ction of Vin ylcop p er 2 w ith En on es
Sch em e 2
ment with a Lewis Acid9,10a (Scheme 2). Similar cycliza-
tions using different silicon groups have been previously
reported by Trost.10b
The chemistry of allylsilanes has been extensively
studied.11 They have proved to be versatile silicon-
containing carbon nucleophiles which readily react with
carbonyl electrophiles12 and enones.13 The reaction often
shows high levels of stereocontrol and involves an
intermediate carbocation which usually evolves with the
loss of the silyl group. The ability of silicon to stabilize a
developing â carbocation is believed to be responsible for
the rate of such reactions.14
(11) (a) Fleming, I.; Barbero, A.; Walter, D. Chem. Rev. 1997, 97,
2063. (b) Yamamoto, Y.; Asao, N. Chem. Rev. 1993, 93, 2207. (c)
Fleming, I.; Dunogues, J .; Smithers, R. Org. React. 1989, 37, 57. (d)
Masse, C. E.; Panek, J . S. Chem. Rev. 1995, 95, 1293. (e) Nativi, C.;
Ricci, A.; Taddei, M. In Frontiers Of Organosilicon Chemistry; Bassin-
dale, A. R., Gaspar, P. P., Eds.; The Royal Society of Chemistry:
Letchworth, 1991; p 332.
(12) See among others: (a) Hosomi, A.; Sakurai, H. Tetrahedron Lett.
1976, 1295. (b) Reetz, M. T.; Drewes, M. W.; Schmitz, A. Angew. Chem.,
Int. Ed. Engl. 1987, 26, 1141. (c) Vara Prasad, J . V. N. Tetrahedron
Lett. 1991, 32, 5857. (d) D’Aniello, F.; Taddei, M. J . Org. Chem. 1992,
57, 5247. (e) Aggarwal, V. K.; Vennall, G. P. Synthesis 1998, 1822. (f)
Marx, A.; Yamamoto, H. Angew. Chem., Int. Ed. 2000, 39, 178. (g)
Hollis, T. K.; Bosnich, B. J . Am. Chem. Soc. 1995, 117, 4570. (h)
Hayashi, T.; Kabeta, K.; Hamachi, I.; Kumada, M. Tetrahedron Lett.
1983, 24, 2865.
(13) See among others: (a) Hosomi, A.; Sakurai, H. J . Am. Chem.
Soc. 1977, 99, 1673. (b) Kno¨lker, H.-J .; J ones, P. G.; Pannek, J . B.
Synlett 1990, 429. (c) Kno¨lker, H.-J .; J ones, P. G.; Pannek, J . B.;
Weinkauf, A. Synlett 1991, 147. (c) Kno¨lker, H.-J .; Foitzik, N.;
Goesmann, H.; Graf, R. Angew. Chem., Int. Ed. Engl. 1993, 32, 1081.
(c) Organ, M. G.; Dragan, V.; Miller, M.; Froese, R. D. J .; Goddard, J .
D. J . Org. Chem. 2000, 65, 3666.
(14) (a) Hanstein, W.; Berwin, H. J .; Traylor, T. G. J . Am. Chem.
Soc. 1970, 92, 829. (b) Wierschke, S. G.; Chandrasekhar, J .; J orgensen,
W. L. J . Am. Chem. Soc. 1985, 107, 1496. (c) Lambert, J . B.; Wang,
G.-T.; Finzel, R. B.; Teramuda, D. H. J . Am. Chem. Soc. 1987, 109,
7838. (d) Green, A. J .; Kuan, Y.-L.; White, J . M. J . Org. Chem. 1995,
60, 2734. (e) Gabelica, V.; Kresge, A. J . J . Am. Chem. Soc. 1996, 118,
3838.
From previous work, it is clear that the behavior of
the tert-butyldiphenylsilyl group is perceptively different
from that observed for the phenyldimethylsilyl group.3b,7
We now describe the full results15 of the reaction of 2 with
enones as a valuable process to obtain carbonyl function-
alized allyl-tert-butyldiphenylsilanes, which show an
interesting reactivity pattern in acid-catalyzed cyclization
reactions.
Thus, tert-butyldiphenylsilylcopper10a reacts with al-
lene at -40 °C giving an allylsilane-vinylcopper inter-
mediate 2 which was treated with different R,â-unsat-
urated ketones 3-11 to afford the products of conjugate
addition 12-20 in very good yields (Scheme 3, Table 1).
The high selection of the vinylcopper species 2 for the
1,4-addition, in contrast with the preferred 1,2-addition
(15) A very preliminary result of the reaction was shown in ref 10.

Cyclization of tert-Butyldiphenylallylsilane Units
J . Org. Chem., Vol. 66, No. 23, 2001 7725
Sch em e 4
Sch em e 5
of the corresponding vinylcuprate,7 indicates the softness
of the former nucleophiles. All the reactions were carried
out in the presence of BF3‚OEt2 which considerably
increased the yield. Remarkably, the reaction of 10 and
11 with 2 was very stereoselective leading to the products
19 and 20 corresponding to the protonation of the
intermediate enolate at the less-hindered face (opposite
the silicon group). The stereochemistry of the optically
active compound 19 was asigned on the basis of 1H NMR
and NOESY experiments. To prove the stereochemistry
of compound 20, a sample of the compound was treated
with NaOH solution. Under such conditions, epimeriza-
tion at CR to carbonyl occurs giving the more stable trans
isomer, whose sterochemistry could be proved with 1H
NMR and 1H NMR/NOESY experiments. The regiose-
lectivity of the reaction of 2 with the R,â-γ,δ-unsaturated
dienone 6 which leads exclusively to the 1,4-addition
product 15 is probably due to the higher accessibility of
the bulky silylcopper reagent for the â position of the
dienone. Reaction of the enantiomerically pure compound
8 with 2 gave a mixture of diastereomers cis/trans in a
1:1 ratio which could be separated. Nevertheless, when
this mixture was treated with a diluted NaOH solution
followed by neutralization, a single trans isomer 17a
could be isolated in 85% total yield (Table 1).
These observations are not consistent with the inter-
mediacy of a carbocation species. On the contrary, the
intervention of an intramolecular ene reaction involving
the carbonyl unit and the allylic moiety bearing the
hydrogen â to carbonyl seems more feasible.
Accordingly, we wondered what would happen if the
hydrogen was not in that position. For that purpose, we
used the â,â-disubstituted ketones 5, 7, and 8. This time,
the cyclization reaction of the oxoallylsilanes 14, 16, and
17a led to cyclopentenols 24-26, where the lack of a
hydrogen â to the carbonyl group caused the silyl group
to come off, probably following the usual SE mechanism
involving stabilized carbocations â to silicon (Scheme 5).
Allylsilane terminated cyclizations of the ketones 18-
20 gave cyclopentanols 27-29 losing the silicon group
again (Scheme 5). Although compounds 18-20 have a
hydrogen â to the carbonyl, the sterical requirements of
these cyclic ketones do not favor a low-energy transition
state for the ene reaction. Moreover, the angular position
of the hydrogen would lead to a very strained structure
having a double bond on a bridgehead carbon which is
an unfavorable process as stated by Bredt.
The high stereocontrol observed in the succesive trans-
formation of 10 f 19 f 28 allows the conversion of (-)-
carvone in a bicyclic alcohol where three new stereogenic
centers of defined configuration are formed with a simple
protocol.
From the above results, it seems quite a general trend
that if the oxoallylsilane comes from an open-chain R,â-
unsaturated ketone and it has an accessible hydrogen γ
to silicon and â to a carbonyl group, this is lost during
cyclization, giving allylsilane containing cyclopentenols.
Otherwise, the tert-butyldiphenylsilyl group is the leav-
ing group, as happens with other silyl groups in a typical
allylsilane terminated cyclization.
It is well known that the addition of allylsilanes to
oxocompounds requires the assistance of a catalyst
(usually a Lewis acid) to proceed at reasonable rates.11
Among the Lewis acids tried in the cyclization reactions,
Et2AlCl showed the best results.
Thus, the intramolecular acid-catalyzed cyclization of
allylsilane-ketones 12, 13, and 15 gave the cyclopentenols
21-23 which maintain the hindered silyl group, in sharp
contrast with the observed behavior for the phenyldi-
methylsilyl analogues where the silyl moiety is always
lost.10a Because of the low electrofugacity of the tert-
butyldiphenylsilyl group, formation of an intermediate
carbocation â to silicon could be followed by the loss of
an adjacent hydrogen to form the double bond, which
would account for the observed result. However, the
reaction proved to be extremely regioselective leading to
a unique allylsilane which corresponds to the elimination
of a hydrogen γ to silicon and â to the carbonyl group
(Scheme 4). Abstraction of hydrogen from other different
positions was never observed. In fact, we were not able
to detect, in any of the studied examples, the elimination
of the allylic hydrogens R to silicon.

7726 J . Org. Chem., Vol. 66, No. 23, 2001
Barbero et al.
Sch em e 6
Sch em e 7
On the basis of the former considerations, two mecha-
nistic alternatives could be put forward to account for
the different behavior of the oxoallylsilanes 12, 13, and
15 toward oxoallylsilanes 14, 16-20. â,â-Disubstituted
ketone 14 and cyclic ketones 16-20 follow the classical
SE reaction through a carbocation â to silicon losing the
silyl group, despite the poor leaving group ability of the
tert-butyldiphenylsilyl group. On the other hand, linear
oxoallylsilanes 12, 13, and 15 react through an ene
mechanism to give allylsilanes as final products (Scheme
6). This behavior is not found with the phenyl dimeth-
ylsilyl group where loss of silicon is always the observed
process.
Sch em e 8
In conclusion, the reaction of allyl-tert-butyldiphenyl-
silylcopper 2 with R,â-unsaturated acid chlorides and
ketones provides a useful way of synthesis of divinyl
ketones and oxoallylsilanes, which upon treatment with
a Lewis acid undergo highly regio- and stereoselective
intramolecular silicon-assisted cyclization reactions to
give silylated cyclopentenones, methylenecyclopentanols,
and allylsilane containing cyclopentenols. Formation of
the latter compounds depends on the ability of a hydrogen
â to the ketone to be lost in an ene-type reaction. When
this is not possible, an intramolecular allylsilane termi-
nated cyclization is the normal process. The low electro-
fugacity of the tert-butyldiphenylsilyl group as compared
with other silyl groups is responsible for the formation
of silicon containing cyclic products when both reactions
can compete.
Allylsilanes are known to give ene reactions,16 either
under thermal or acid-catalyzed conditions. From the
classical mechanism standpoint, it is generally agreed
upon that the concerted ene reaction involves a highly
asynchronous transition state featuring a well-developed
C-C bond prior to a relatively late proton transfer toward
the oxygen.17 This will be favored by the stabilization of
the partial positive charge at the â carbon atom to silicon.
It was noted before that only hydrogens â to carbonyl
are involved in the ene reaction, whereas allylic hydro-
gens R to silicon seem to be unreactive. The high level of
regioselectivity obtained in the ene reaction could be
interpreted in terms of the greater accessibility of the
hydrogen â to the carbonyl group to be abstracted,
probably due to the bulky tert-butyldiphenylsilyl group
which hinders the hydrogens R to silicon.
To complete the study, divinyl ketones 30 and 31 were
obtained with excellent yield by reaction of 2 with R,â-
unsaturated acid chlorides (Scheme 7). The silicon-
assisted Nazarov18 reaction of divinyl ketones 30 and 31,
in the presence of TFA, affords a good yield of methyl-
enecyclopentanones 32 and 33, which maintain the
hindered silyl group (Scheme 8). This time the loss of the
hydrogen is not univocal leading to vinylsilane 32 and
allylsilane 33 without apparent differentiation, which
allows us to think about an intermediate carbocation â
to silicon in which both hydrogens R and γ to silicon can
be lost.
Exp er im en ta l Section
All melting points are uncorrected. All reagents were of
commercial quality from freshly opened containers or were
purified before use. THF was distilled under N2 from purple
solutions of sodium benzophenone ketyl. Allene (97%) was
supplied by Air-Products in lecture bottles. Commercial re-
agents 3-11 were purchased from Aldrich. The preparation
of R,â-unsaturated acid chlorides was reported previously.10a
IR spectra were recorded on a FT/IR spectrophotometer as neat
liquid films. H and 13C NMR spectra were taken at 300 and
1
50 MHz, respectively. GC/MS spectra were recorded operating
either in the CI mode or in the EI mode (70 eV). The
purification of the products was performed by flash chroma-
tography on Silica Gel 60 (Merck, 230-400 mesh). Nonaqueous
reactions were carried out under nitrogen atmosphere. Com-
pounds 25, 27, and 29 were described in a previous article.10a
Unless otherwise noted, yields of all compounds are of purified
material. The stereochemistry of the compounds has been
(16) (a) Dubac, J .; Laporterie, A. Chem. Rev. 1987, 87, 319. (b) Monti,
H.; Audran, G.; Feraud, M.; Monti, J .-P.; Leandri, G. Tetrahedron 1996,
52, 6685. (c) Monti, H.; Feraud, M. Synth. Commun. 1996, 26, 1721.
(d) Mikami, K.; Shimizu, M.; Nakai, T. J . Org. Chem. 1991, 56, 2952.
(e) Shimizu, M.; Mikami, K. J . Org. Chem. 1992, 57, 6105. (f) D’Aniello,
F.; Mann, A.; Mattii, D.; Taddei, M. J . Org. Chem. 1994, 59, 3762. (g)
Monti, H.; Laval, G.; Feraud, M. Eur. J . Org. Chem. 1999, 1825, 5. (h)
Robertson, J .; O’Connor, G.; Middleton, D. S. Tetrahedron Lett. 1996,
37, 3411. (i) Hojo, M.; Murakami, C.; Aihara, H.; Tomita, K.; Miura,
K.; Hosomi, A. J . Organomet. Chem. 1995, 499, 155.
(17) (a) Cai, J .; Davies, A. G. J . Chem. Soc.., Perkin Trans. 2 1992,
1743. (b) Hoffmann, H. M. R. Angew. Chem., Int. Ed. Engl. 1969, 8,
556. (c) Conia, J .-M.; Le Perchec, P. Synthesis 1975, 1. (d) Mikami, K.;
Shimizu, M. Chem. Rev. 1992, 92, 1021. (e) Snider, B. B. Comprehen-
sive Organic Synthesis; Pergamon: Oxford, 1991; Vol. 2, pp 527-561
and Vol. 5, pp 1-27.
(18) (a) Denmark, S. E.; J ones, T. K. J . Am. Chem. Soc. 1982, 104,
2642. (b) Denmark, S. E.; Wallace, M. A.; Walker, C. B. J . Org. Chem.
1990, 55, 5543.
1
assigned on the basis of H NMR and NOESY experiments.
Silylcu p r a tion of Allen e. P r ep a r a tion of In ter m ed ia te
2. A solution of tert-butyldiphenylsilyllithium19 (3 mmol)
prepared in THF (3 mL) was added by syringe to a stirred
suspension of copper(I) cyanide (269 mg, 3 mmol) in THF (5
mL) at 0 °C. The resulting green-black mixture was stirred at
this temperature for 30 min and then used immediately. The
solution of tert-butyldiphenylsilylcopper (3 mmol) in THF (8
mL) was cooled at -40 °C, and a slight excess of allene was
(19) Cuadrado, P.; Gonza´lez, A. M.; Pulido, F. J . Synth. Commun.
1989, 19, 275.

Cyclization of tert-Butyldiphenylallylsilane Units
J . Org. Chem., Vol. 66, No. 23, 2001 7727
added from a balloon. The mixture was stirred for 1 h, and
the reagent 2 was used immediately.
Colorless oil. [R]20 +3.57 (c 1.10, CHCl3). IR (neat): 1710,
D
1
1640, 1110. H NMR (CDCl3, 300 MHz): 7.73-7.35 (10H, m),
Rea ction of In ter m ed ia te 2 w ith r,â-Un sa tu r a ted
Keton es. BF3‚Et2O (0.38 mL, 3 mmol) was added at -78 °C
to a stirred solution of cuprate 2 (3 mmol), and the mixture
was stirred for 10 min at this temperature. A solution of 3.6
mmol of ketones 3-11 in THF (5 mL) was then added dropwise
at -78 °C, and the resulting mixture was kept at this
temperature for 1 h. After gentle warming to 0 °C (over 0.5
h), the mixture was quenched with basic saturated ammonium
chloride solution and extracted twice with Et2O. The organic
layer was dried (MgSO4), evaporated, and chromatographed
(EtOAc:hexanes) to give the allylsilanes 12-20.
4.72 (1H, s), 4.65 (1H, s), 2.55 (1H, dd, J ) 12.0 and 4.5), 2.33
(1H, ddd J ) 12.0, 3.9, and 2.1), 2.13-2.01 (3H, m), 1.88-
1.82 (3H, m), 1.39-1.29 (2H, m), 1.18 (3H, s), 1.07 (3H, s), 1.04
(9H, s), 1.02 (3H, d, J ) 6.0). 13C NMR (CDCl3, 75 MHz): 211.5,
150.7, 136.2, 136.0, 134.8, 134.4, 129.0, 127.4, 113.0, 55.4, 52.4,
41.4, 36.2, 34.8, 28.9, 27.9, 24.6, 22.3, 21.9, 18.5, 12.4. MS(EI)
t
m/z: 375 (M+ - Bu, 7%), 239, 199. Anal. Calcd for C29H40
-
OSi: C, 80.49; H, 9.32. Found: C, 80.61; H, 9.41.
[2R,5R]-2-(3-ter t-Bu tyld ip h en ylsilylm eth yl-2-m eth yl-3-
bu ten -2-yl)-5-m eth yl-cycloh exa n -1-on e (17b). 41% from 8.
Colorless oil. [R]20 +44.3 (c 0.90, CHCl3). IR (neat): 1710,
D
1
5-ter t-Bu tyld ip h en ylsilylm eth yl-3,4-d im eth yl-5-h exen -
2-on e (12). 88% from 3. Colorless oil. IR (neat): 1700, 1625,
1640, 1110. H NMR (CDCl3, 300 MHz): 7.72-7.34 (10H, m),
4.72 (1H, s), 4.66 (1H, s), 2.58-2.50 (2H, m), 2.27 (1H, m), 2.11
(1H, d, J ) 16.8), 2.0 (1H, d, J ) 16.8), 2.08 (1H, m), 1.78 (1H,
m), 1.69-1.63 (2H, m), 1.53 (1H, m), 1.12 (3H, s), 1.05 (3H, s),
1.03 (9H, s), 0.95 (3H, d, J ) 7.0). 13C NMR (CDCl3, 75 MHz):
212.9, 150.5, 136.2, 136.1, 134.8, 134.3, 129.0, 127.4, 113.2,
55.2, 50.5, 42.0, 32.2, 31.4, 27.9, 25.1, 24.7, 22.7, 19.7, 18.5,
12.4. MS(EI) m/z: 375 (M+ - tBu, 15%), 239, 199. Anal. Calcd
for C29H40OSi: C, 80.49; H, 9.32. Found: C, 80.84; H, 9.55.
[2R,3R,5R]-3-(3-ter t-Bu tyld ip h en ylsilyl-1-p r op en -2-yl)-
5-isop r op en yl-2-m eth ylcycloh exa n on e (19). 75% from 10.
1
1100. H NMR (CDCl3, 300 MHz): 7.72-7.27 (10H, m), 4.70
(1H, s), 4.64 (1H, s), 2.50 (1H, dq, J ) 9.0, 7.0), 2.22 (1H, d, J
) 15.5), 2.08-2.02 (2H, m), 2.01 (3H, s), 1.06 (9H, s), 0.86 (3H,
d, J ) 7.0), 0.74 (3H, d, J ) 7.0). 13C NMR (CDCl3, 75 MHz):
212.7, 147.6, 136.2, 136.1, 134.6, 134.2, 129.1, 127.5, 112.2,
51.5, 44.3, 28.7, 27.8, 18.5, 17.5, 17.4, 15.3. MS(EI) m/z: 321
t
(M+ - Bu, 19%), 243, 199 (100). Anal. Calcd for C25H34OSi:
C, 79.31; H, 9.05. Found: C, 79.45; H, 9.12.
6-ter t-Bu tyld ip h en ylsilylm eth yl-5-m eth yl-6-h ep ten -3-
on e (13). 89% from 4. Colorless oil. IR (neat): 1700, 1620,
Colorless oil. [R]20 +34.6 (c 1.20, CHCl3). IR (neat): 1705,
D
1
1
1100. H NMR (CDCl3, 300 MHz): 7.68-7.33 (10H, m), 4.61
1640, 1100. H NMR (CDCl3, 300 MHz): 7.65-7.31 (10H, m),
(1H, s), 4.60 (1H, s), 2.30-2.13 (5H, m), 2.20 (2H, s), 1.07 (9H,
s), 0.96 (3H, t, J ) 7.2), 0.80 (3H, d, J ) 6.5). 13C NMR (CDCl3,
75 MHz): 210.6, 150.6, 136.3, 134.5, 129.1, 127.4, 108.9, 48.6,
4.8 (1H, s), 4.7 (1H, s), 4.6 (1H, s), 4.4 (1H, s), 2.54 (1H, tt, J
) 9.5 and 4.5), 2.47-2.34 (3H, m), 2.22 (1H, d, J ) 13.8), 2.13
(1H, d, J ) 13.8), 2.2 (1H, m), 1.93 (1H, dt, J ) 13.6 and 4.5),
1.62 (3H, s), 1.54 (1H, ddd, J ) 13.6, 9.5, and 4.5), 1.04 (9H,
s), 0.76 (3H, d, J ) 6.5). 13C NMR (CDCl3, 75 MHz): 213.7,
147.0, 144.7, 136.2, 136.1, 134.4, 134.1, 129.2, 127.5, 112.9,
110.5, 46.8, 45.4, 44.4, 39.8, 31.0, 22.7, 21.1, 20.1, 18.5, 11.6.
MS(EI) m/z: 373 (M+ - tBu, 18%), 332, 239, 199. Anal. Calcd
for C29H38OSi: C, 80.87; H, 8.89. Found: C, 81.08; H, 8.97.
cis-1-Acetyl-2-(3-ter t-bu tyld ip h en ylsilyl-1-p r op en -2-yl-
)cycloh exa n e (20). 81% from 11. White solid, mp 91-92 °C.
IR (neat): 1700, 1625, 1100. 1H NMR (CDCl3, 300 MHz):
7.70-7.33 (10H, m), 4.80 (1H, s), 4.58 (1H, s), 2.83 (1H, m),
2.42 (1H, d, J ) 14.3), 2.15 (1H, d, J ) 14.3), 2.0 (3H, s), 1.79-
1.50 (6H, m), 1.10 (9H, s), 1.30-1.0 (3H, m). 13C NMR (CDCl3,
75 MHz): 212.7, 148.0, 136.2, 136.1, 134.4, 134.2, 129.1, 127.5,
110.8, 48.6, 45.3, 31.6, 27.8, 27.5, 26.0, 25.6, 21.7, 20.3, 18.6.
MS(EI) m/z: 404 (M+, 1%), 347, 269, 199 (100). Anal. Calcd
for C27H36OSi: C, 80.14; H, 8.97. Found: C, 80.39; H, 9.09.
Allylsilan e Ter m in ated Cyclization s.10 EtAlCl2 (2.4 mmol,
1.8 M in toluene) was added slowly to a solution of 12-20 (2
mmol) in toluene (8 mL) at 0 °C under nitrogen. After stirring
for 1 h at 0 °C, brine was added (5 mL), and the mixture was
extracted with Et2O, dried, and evaporated. Purification by
flash chromatography gave 21-29. Compounds 25, 27, and
29 were prepared before.10a,b
36.6, 35.8, 27.8, 19.4, 18.7, 18.5, 7.7. MS(EI) m/z: 321 (M+
-
tBu, 19%), 243, 199 (100). Anal. Calcd for C25H34OSi: C, 79.31;
H, 9.05. Found: C, 79.50; H, 9.20.
5-ter t-Bu tyld ip h en ylsilylm eth yl-4,4-d im eth yl-5-h exen -
2-on e (14). 90% from 5. Colorless oil. IR (neat): 1700, 1620,
1
1100. H NMR (CDCl3, 300 MHz): 7.72-7.27 (10H, m), 4.72
(1H, s), 4.64 (1H, s), 2.47 (2H, s), 2.16 (2H, s), 2.08 (3H, s),
1.05 (6H, s), 1.04 (9H, s). 13C NMR (CDCl3, 75 MHz): 208.5,
150.4, 136.2, 134.5, 129.0, 127.4, 112.0, 53.5, 39.8, 32.2, 27.8,
t
26.8, 18.4, 12.8. MS(EI) m/z: 321 (M+ - Bu, 15%), 263, 199
(100), 43. Anal. Calcd for C25H34OSi: C, 79.31; H, 9.05.
Found: C, 79.58; H, 9.27.
5-ter t-Bu t yld ip h en ylsilylm et h yl-4-[2,6,6-t r im et h yl-1-
cycloh exen -1-yl]-5-h exen -2-on e (15). 85% from 6. Colorless
1
oil. IR (neat): 1710, 1625, 1100. H NMR (CDCl3, 300 MHz):
7.76-7.33 (10H, m), 4.62 (1H, s), 4.57 (1H, s), 3.53 (1H, d, J )
8.7), 3.04 (1H, dd, J ) 18 and 8.7), 2.46 (1H, d, J ) 18), 2.17
(1H, d, J ) 18), 2.09 (3H, s), 1.97 (1H, d, J ) 18), 1.92 (2H, t,
J ) 6), 1.58 (2H, t, J ) 6), 1.50-1.40 (2H, m), 1.44 (3H, s),
1.04 (3H, s), 1.01 (9H, s), 0.99 (3H, s). 13C NMR (CDCl3, 75
MHz): 207.3, 145.9, 138.7, 136.3, 134.7, 130.7, 129.0, 127.5,
127.3, 112.2, 48.2, 42.1, 40.2, 36.0, 34.0, 30.0, 28.5, 27.8, 21.4,
t
19.4, 18.4, 16.3. MS(EI) m/z: 415 (M+ - Bu, 5%), 357, 199
(73). Anal. Calcd for C32H44OSi: C, 81.30; H, 9.38. Found: C,
81.59; H, 9.55.
(E)-1,4,5-Tr im eth yl-3-ter t-bu tyld ip h en ylsilylm eth yl-3-
cyclop en ten -1-ol (21a ). 68% from 12. Colorless oil. IR
(neat): 3530, 3450, 1100, 900. 1H NMR (CDCl3, 300 MHz):
7.65-7.27 (10H, m), 2.17 (1H, d, J ) 15), 2.15 (1H, d, J ) 15),
2.10-2.0 (1H, m), 2.06 (1H, d, J ) 15.5), 1.87 (1H, d, J ) 15.5),
1.46, (3H, s), 1.40 (1H, s), 1.08 (9H, s), 0.98 (3H, s), 0.65 (3H,
d, J ) 7.0). 13C NMR (CDCl3, 75 MHz): 136.1, 136.0, 134.6,
134.3, 133.2, 129.1, 129.0, 127.4, 79.2, 55.6, 51.7, 27.6, 22.4,
3-(3-ter t-Bu tyld ip h en ylsilyl-1-p r op en -2-yl)-3-m eth ylcy-
clop en ta n -1-on e (16). 87% from 7. Colorless oil. IR (neat):
1730, 1100, 900. 1H NMR (CDCl3, 300 MHz): 7.82-7.34 (10H,
m), 4.69 (1H, s), 4.67 (1H, s), 2.24 (1H, d, J ) 17.6), 2.17 (2H,
s), 2.27-2.13 (2H, m), 2.03 (1H, d, J ) 17.6), 1.97-1.80 (2H,
m), 1.11 (3H, s), 1.01 (9H, s). 13C NMR (CDCl3, 75 MHz): 219.0,
150.0, 136.3, 134.5, 129.2, 127.5, 111.4, 51.0, 46.3, 36.5, 33.5,
27.9, 25.6, 18.5, 13.2. MS(EI) m/z: 319 (M+ - tBu, 18%), 239,
199, 41 (100). Anal. Calcd for C25H32OSi: C, 79.73; H, 8.56.
Found: C, 79.91; H, 8.69.
18.4, 14.1, 12.7, 12.1. MS(EI) m/z: 378 (M+, 8%), 321 (M+
tBu, 8%), 239, 199 (100). Anal. Calcd for C25H34OSi: C, 79.31;
H, 9.05. Found: C, 79.57; H, 9.19.
-
(Z)-1,4,5-Tr im eth yl-3-ter t-bu tyld ip h en ylsilylm eth yl-3-
cyclop en ten -1-ol (21b). 17% from 12. Colorless oil. IR
(neat): 3530, 3450, 1100, 900. 1H NMR (CDCl3, 300 MHz):
7.65-7.27 (10H, m), 2.20 (1H, d, J ) 15), 2.09-2.03 (3H, m),
1.89 (1H, d, J ) 15), 1.40 (3H, s), 1.07 (9H, s), 1.06 (3H, s),
0.80 (1H, s), 0.75 (3H, d, J ) 7.0). 13C NMR (CDCl3, 75 MHz):
136.1, 136.0, 134.7, 134.3, 131.9, 129.3, 129.2, 127.4, 127.3,
77.9, 52.4, 52.3, 27.6, 25.4, 18.3, 12.3, 11.9, 11.1. MS(EI) m/z:
378 (M+, 7%), 321 (M+ - tBu, 8%), 239, 199 (100). Anal. Calcd
for C25H34OSi: C, 79.31; H, 9.05. Found: C, 79.70; H, 9.29.
1-Eth yl-4-m eth yl-3-ter t-bu tyld ip h en ylsilylm eth yl-3-cy-
clop en ten -1-ol (22). 85% from 13. Colorless oil. IR (neat):
3-(3-ter t-Bu t yld ip h en ylsilyl-1-p r op en -2-yl)cycloh ex-
a n on e (18). 87% from 9. Colorless oil. IR (neat): 1705, 1630,
1
1100. H NMR (CDCl3, 300 MHz): 7.65-7.32 (10H, m), 4.73
(1H, s), 4.59 (1H, s), 2.22 (2H, s), 2.20-2.02 (4H, m), 1.89-
1.63 (3H, m), 1.41-1.11 (2H, m), 1.07 (9H, s). 13C NMR (CDCl3,
75 MHz): 211.4, 149.0, 136.5, 134.4, 134.3, 129.2, 127.5, 109.2,
46.8, 45.0, 41.1, 30.1, 27.8, 24.7, 19.3, 18.5. MS(EI) m/z: 319
t
(M+ - Bu, 12%), 239, 199, 41 (100). Anal. Calcd for C25H32
-
OSi: C, 79.73; H, 8.56. Found: C, 80.01; H, 8.77.
[2S,5R]-2-(3-ter t-Bu tyld ip h en ylsilylm eth yl-2-m eth yl-3-
bu ten -2-yl)-5-m eth yl-cycloh exa n -1-on e (17a ). 44% from 8.

7728 J . Org. Chem., Vol. 66, No. 23, 2001
Barbero et al.
1
3400, 1100. H NMR (CDCl3, 300 MHz): 7.65-7.34 (10H, m),
1600, 1090 cm-1. 1H NMR (CDCl3, 300 MHz): 7.66-7.27 (10H,
m), 5.91 (1H, m), 5.34 (1H, s), 5.24 (1H, s), 2.58 (2H, s), 2.40-
2.27 (4H, m), 1.77 (2H, qn, J ) 7.5), 1.06 (9H, s). 13C NMR
(CDCl3, 75 MHz): 195.5, 146.0, 145.0, 143.2, 136.4, 133.7,
129.1, 127.4, 121.8, 33.8, 31.3, 27.7, 22.5, 18.5, 14.8. MS(EI)
m/z: 374 (M+, 4%), 317 (100), 239. Anal. Calcd for C25H30OSi:
C, 80.16; H, 8.07. Found: C, 80.41; H, 8.28.
2.24 (1H, d, J ) 16.5), 2.17 (2H, s), 2.06 (1H, d, J ) 16.5), 2.03
(1H, d, J ) 16.5), 1.85 (1H, d, J ) 16.5), 1.47 (3H, s), 1.38
(2H, q, J ) 7.2), 1.20 (1H, s), 1.10 (9H, s), 0.76 (3H, t, J )
7.2). 13C NMR (CDCl3, 75 MHz): 136.0, 134.8, 134.6, 129.6,
129.1, 127.4, 127.3, 79.4, 51.9, 51.4, 33.0, 27.6, 18.3, 14.2, 12.2,
8.7. MS(EI) m/z: 378 (M+, 5%), 321 (M+ - tBu, 5%), 239, 199
(100). Anal. Calcd for C25H34OSi: C, 79.31; H, 9.05. Found:
C, 79.61; H, 9.24.
3-ter t-Bu t yld ip h en ylsilylm et h yl-4-[2,6,6-t r im et h yl-1-
cycloh exen -1-yl]-3-cyclop en ten -1-ol (23). 77% from 15.
Colorless oil. IR (neat): 3590, 3400, 1100, 920. 1H NMR
(CDCl3, 300 MHz): 7.96-7.32 (10H, m), 2.46 (1H, dd, J ) 16.3
and 6.6), 2.27-1.97 (5H, m), 2.09 (2H, s), 1.67 (2H, t, J ) 6),
1.62 (1H, s), 1.43 (2H, qn, J ) 6), 1.33 (3H, s), 1.14 (3H, s),
1.03 (9H, s), 0.94 (3H, s), 0.84 (3H, s). 13C NMR (CDCl3, 75
MHz): 135.7, 134.8, 134.7, 136.1, 132.7, 132.6, 129.1, 128.7,
127.4, 77.3, 54.4, 52.6, 40.0, 35.4, 31.8, 30.1, 29.3, 27.9, 27.6,
20.8, 19.2, 18.2, 12.9. MS(EI) m/z: 472 (M+, 3%), 199 (100),
57. Anal. Calcd for C32H44OSi: C, 81.30; H, 9.38. Found: C,
81.62; H, 9.59.
3-Meth ylen e-1,4,4-tr im eth ylcyclop en ta n -1-ol (24). 67%
from 14. Colorless oil. IR (neat): 3350, 3400, 1660, 880. 1H
NMR (CDCl3, 300 MHz): 4.89 (1H, s), 4.83 (1H, s), 2.55 (1H,
d, J ) 15.7), 2.47 (1H, d, J ) 15.7), 1.77 (1H, d, J ) 13.6), 1.73
(1H, d, J ) 13.6), 1.44 (1H, s), 1.35 (3H, s), 1.24 (3H, s), 1.12
(3H, s). 13C NMR (CDCl3, 75 MHz): 160.7, 105.0, 77.3, 56.3,
49.3, 41.4, 31.1, 30.1, 28.2. MS(EI) m/z: 140 (M+, 3%). Anal.
Calcd for C9H16O: C, 77.09; H, 11.50. Found: C, 77.48; H,
11.76.
[1S,3R,6S]-3,7,7-Tr im eth yl-8-m eth ylen ebicyclo[4.3.0]-
n on a n -1-ol (26). 70% from 17. White solid, mp 83-84 °C.
[R]20D -39.16 (c 0.95, CHCl3). IR (neat): 3600, 3450, 1645, 880.
1H NMR (CDCl3, 300 MHz): 4.93 (1H, m), 4.88 (1H, m), 2.80
(1H, dt, J ) 16.8 and 2.9), 2.24 (1H, ddd, J ) 16.8, 3.4, and
1.6), 1.93 (1H, ddd, J ) 12.9, 3.4, and 2.3), 1.76 (1H, m), 1.64
(1H, m), 1.49 (1H, ddd, J ) 12.3, 5.7, and 1.9), 1.38 (3H, s),
1.36-1.30 (2H, m), 1.17 (1H, t, J ) 12.6), 1.07-0.86 (2H, m),
1.03 (3H, s), 0.91 (3H, d, J ) 6.1). 13C NMR (CDCl3, 75 MHz):
160.8, 105.9, 80.0, 56.0, 46.3, 45.2, 44.2, 34.0, 33.9, 30.4, 28.2,
25.9, 22.2. MS(EI) m/z: 194 (M+, 11%), 176. Anal. Calcd for
1-(1-Cycloh exen yl)-2-ter t-bu tyld ip h en ylsilylm eth yl-2-
p r op en -1-on e (31). 85%. Colorless oil. IR (neat): 1690, 1640,
1
1610, 1110. H NMR (CDCl3, 300 MHz): 7.65-7.31 (10H, m),
6.0 (1H, m), 5.25 (1H, s), 5.17 (1H, s), 2.60 (2H, s), 2.07-2.03
(2H, m), 1.96-1.90 (2H, m), 1.55-1.43 (4H, m), 1.07 (9H, s).
13C NMR (CDCl3, 75 MHz): 199.4, 144.8, 142.0, 137.0, 136.4,
133.6, 129.1, 127.4, 121.5, 27.7, 25.7, 23.5, 21.9, 21.4, 18.5, 15.3.
MS(EI) m/z: 388 (M+, 5%), 331, 199. Anal. Calcd for C26H32
-
OSi: C, 80.36; H, 8.30. Found: C, 80.53; H, 8.39.
Dir ected Na za r ov Rea ction s. A solution of 30 or 31 (2
mmol) in THF (3 mL) was stirred at room temperature, and
TFA (0.46 mL, 6 mmol) was added with continuous stirring.
The solution was heated to 60 °C and stirred for an additional
period of 1 h. The reaction was quenched with a saturated
solution of sodium bicarbonate (5 mL). After extraction with
Et2O, the ethereal layer was washed twice with brine, dried,
and concentrated. The crude product was purified by flash
chromatography (EtOAc:hexanes) to give 32 or 33.
(E)-2-ter t-Bu tyldiph en ylsilylm eth ylen e-cis-bicyclo[3.3.0]-
octa n -2-on e (32). 73% from 30. Colorless oil. IR (neat): 1690,
1
1110, 900. H NMR (CDCl3, 300 MHz): 7.69-7.28 (10H, m),
7.17 (1H, t, J ) 2.6), 2.68 (1H, td, J ) 9.2 and 4), 2.43 (1H,
dqn, J ) 2 and 8), 2.19 (1H, ddd, J ) 18.4, 8.4, and 3.2), 2.06-
1.84 (3H, m), 1.70-1.60 (2H, m), 1.15 (2H, qn, J ) 7), 1.08
(9H, s). 13C NMR (CDCl3, 75 MHz): 209.8, 156.0, 135.9, 133.2,
133.0, 129.4, 129.2, 128.5, 127.8, 52.1, 37.7, 34.5, 33.8, 30.0,
t
27.2, 26.1, 18.4. MS(EI) m/z: 374 (M+, 5%), 317 (M+ - Bu,
100), 239. Anal. Calcd for C25H30OSi: C, 80.16; H, 8.07.
Found: C, 80.38; H, 8.17.
cis-2-ter t-Bu tyld ip h en ylsilylm eth ylbicyclo[3.3.0]oct-3-
en -2-on e (33). 75% from 31. Colorless oil. IR (neat): 1690,
1
1110, 810. H NMR (CDCl3, 300 MHz): 7.66-7.34 (10H, m),
6.45 (1H, d, J ) 1.1), 2.55 (1H, m), 2.32 (1H, d, J ) 14.8), 2.22-
2.15 (2H, m), 1.68-1.53 (3H, m), 1.53-1.10 (5H, m), 1.06 (9H,
s). 13C NMR (CDCl3, 75 MHz): 211.5, 160.0, 140.3, 136.1,
134.0, 133.7, 129.2, 127.5, 127.4, 44.7, 38.4, 27.8, 27.7, 22.7,
21.1, 21.0, 18.4, 6.3. MS(EI) m/z: 331 (M+ - tBu, 90), 253, 199,
57 (100). Anal. Calcd for C26H32OSi: C, 80.36; H, 8.30. Found:
C, 80.66; H, 8.48.
C
13H22O: C, 80.35; H, 11.41. Found: C, 80.51; H, 11.52.
[1S,3R,5R,8R]-8-Met h yl-6-m et h ylen e-3-isop r op en yl-
bicyclo[3.2.1]octa n -1-ol (28). 65% from 19. White solid, mp
80-82 °C. [R]20D -12.2 (c 1.05, CHCl3). IR (neat): 3340, 1650,
880. 1H NMR (CDCl3, 300 MHz): 4.87 (2H, s), 4.70 (2H, s),
2.45-2.33 (4H, m), 1.90 (1H, ddd, J ) 11.8, 5, and 1), 1.70
(3H, s), 1.67-1.55 (4H, m), 1.45 (1H, td, J ) 11.8 and 2), 0.95
(3H, d, J ) 7). 13C NMR (CDCl3, 75 MHz): 151.7, 148.5, 108.8,
107.2, 78.9, 50.3, 48.6, 45.4, 40.7, 39.3, 38.9, 20.8, 13.7. MS-
(EI) m/z: 192 (M+, 15%), 177, 159. Anal. Calcd for C13H20O:
C, 81.20; H, 10.48. Found: C, 81.38; H, 10.57.
Ack n ow led gm en t. This work was supported by the
D.G.E.S. (projects PB96-0357 and BQU2000-0867) from
the Ministry of Education and Science of Spain and from
the “J unta de Castilla y Leo´n” (projects VA43/98 and
VA023/01). The authors thank Dr. Daniel Miguel San
J ose´ for expert assistance with X-ray crystallographic
work.
Rea ction of In ter m ed ia te 2 w ith Acid Ch lor id es. A
solution of the acid chlorides in THF (3.6 mmol) was added to
the cuprate reagent 2 (3 mmol) at -40 °C, and the resulting
solution was stirred at this temperature for 1 h. After gentle
warming to 0 °C (over 0.5 h), the mixture was quenched with
basic saturated ammonium chloride solution and extracted
twice with Et2O. The organic layer was dried over MgSO4 and
rotoevaporated. Purification by flash chromatography (EtOAc:
hexanes) gave the allylsilanes 30-31.
Su p p or tin g In for m a tion Ava ila ble: X-ray figure and
data of cis-3-methylene-4-phenylcyclopentan-1-ol (phenylure-
thane derivative). This material is available free of charge via
the Internet at http://pubs.acs.org.
1-(1-Cyclop en ten yl)-2-ter t-bu tyld ip h en ylsilylm eth yl-2-
p r op en -1-on e (30). 80%. Colorless oil. IR (neat): 1700, 1620,
J O0158736