Catalytic Cyclization/Silylation of Dienes Containing 1,1-Disubstituted Olefins Using Organolanthanide and Group 3 Organometallic Complexes

Article abstract of DOI:10.1021/jo972359k

The catalytic cyclization/silylation reaction of hindered dienes has been investigated using the relatively unhindered complexes Me₂Si(C₅H₃SiMe₃) ₂YCH(TMS)₂ and [Cp^TMS₂LnMe]₂ (Ln = Y, Lu). A wide variety of dienes and trienes bearing a number of functional groups were cychzed, affording silanes containing quaternary centers in a diastereoselective fashion and in good yield. The products can be oxidized using one of several different protocols, yielding alcohols for further functionalization.

Full text of DOI:10.1021/jo972359k

3386
J . Org. Chem. 1998, 63, 3386-3396
Ca ta lytic Cycliza tion /Silyla tion of Dien es Con ta in in g
1,1-Disu bstitu ted Olefin s Usin g Or ga n ola n th a n id e a n d Gr ou p 3
Or ga n om eta llic Com p lexes
Gary A. Molander* and Eric D. Dowdy
Department of Chemistry and Biochemistry, University of Colorado at Boulder,
Boulder, Colorado 80309-0215
Herbert Schumann
Institut fu¨r Anorganische und Analytische Chemie der Technischen Universita¨t Berlin, Strasse des 17.
J uni 135, 10623 Berlin, Germany
Received December 31, 1997
The catalytic cyclization/silylation reaction of hindered dienes has been investigated using the
relatively unhindered complexes Me2Si(C5H3SiMe3)2YCH(TMS)2 and [CpTMS2LnMe]2 (Ln ) Y, Lu).
A wide variety of dienes and trienes bearing a number of functional groups were cyclized, affording
silanes containing quaternary centers in a diastereoselective fashion and in good yield. The products
can be oxidized using one of several different protocols, yielding alcohols for further functionalization.
In tr od u ction
been carried out utilizing stoichiometric anionic olefin
insertion chemistry. Several structurally diverse systems
have proven amenable to this protocol, including those
incorporating hindered double bonds.9 The common
starting point for these reactions is an unsaturated alkyl
halide. Lithium-halogen exchange or Grignard reagent
formation affords an organometallic, and the presence
of certain additives facilitates intramolecular olefin
insertion. Although these methods allow the construction
of interesting molecules (eq 1), the requirement of initiat-
ing the reaction at a halide center and the necessity of
utilizing stoichiometric amounts of harsh organometallic
reagents, intolerant of polar functional groups, detract
from the overall value of the method.
Organolanthanide and group 3 metallocene complexes
have been the subject of extensive investigations1 into
their ability to mediate hydrogenation,2 hydroamination,3
hydroboration,4 hydrostannylation,5 and hydrosilylation
reactions of olefins,6 as well as cyclization7 and cycli-
zation/silylation reactions of polyunsaturated sub-
strates.6a,b,d,f,h,8 The reactivity of these catalysts is pre-
dominantly sterically driven, which allows exquisite
selectivity in complicated, polyfunctional substrates.
This same steric discrimination, however, has heretofore
inhibited reaction with other than monosubstituted ole-
fins.
Historically, cyclization/functionalization reactions of
hindered olefins have been achieved by employing a
variety of approaches. For example, investigations have
(1) Molander, G. A. Chemtracts, in press.
(2) (a) J eske, G.; Lauke, H.; Mauermann, H.; Swepston, P. N.;
Schumann, H.; Marks, T. J . J . Am. Chem. Soc. 1985, 107, 8111. (b)
Molander, G. A.; Hoberg, J . O. J . Org. Chem. 1992, 57, 3266. (c) Haar,
C. M.; Stern, C. L.; Marks, T. J . Organometallics 1996, 15, 1765. (d)
Roesky, P. W.; Denninger, U.; Stern, C. L.; Marks T. J . Organometallics
1997, 16, 4486. (e) Roesky, P. W.; Stern, C. L.; Marks, T. J . Organo-
metallics 1997, 16, 4705.
(3) (a) Gagne´, M. R.; Stern, C. L.; Marks, T. J . J . Am. Chem. Soc.
1992, 114, 275. (b) Giardello, M. A.; Conticello, V. P.; Brard, L.; Gagne´,
M. R.; Marks T. J . J . Am. Chem. Soc. 1994, 116, 10241. (c) Li, Y.;
Marks, T. J . Organometallics 1996, 15, 3770. (d) Li, Y.; Marks, T. J .
J . Am. Chem. Soc. 1996, 118, 9295.
(4) (a) Harrison, K. N.; Marks, T. J . J . Am. Chem. Soc. 1992, 114,
9220. (b) Bijpost, E. A.; Duchateau, R.; Teuben, J . H. J . Mol. Catal.
1995, 95, 121.
(5) Voskoboynikov, A. Z.; Beletskaya, I. P. New J . Chem. 1995, 19,
723.
(6) (a) Fu, P. F.; Brard, L.; Li, Y.; Marks, T. J . J . Am. Chem. Soc.
1995, 117, 7157. (b) Molander, G. A.; Nichols, P. J . J . Am. Chem. Soc.
1995, 117, 4415. (c) Molander, G. A.; Retsch, W. H. Organometallics
1995, 14, 4570. (d) Molander, G. A.; Nichols, P. J . J . Org. Chem. 1996,
61, 6040. (e) Molander, G. A.; Winterfeld, J . J . Organomet. Chem. 1996,
524, 275. (f) Molander, G. A.; Retsch, W. H. J . Am. Chem. Soc. 1997,
119, 8817. (g) Molander G. A.; J ulius, M. J . Org. Chem. 1992, 57, 6347.
(h) Onozawa, S.; Sakakura, T.; Tanaka, M. Tetrahedron Lett. 1994,
35, 8177. (i) Sakakura, T.; Lautenschlager, H.; Tanaka, M. J . Chem.
Soc., Chem. Commun. 1991, 40.
To address these limitations, catalytic carbometalation
systems were developed that operated on dienes, thus
foregoing the requirement of a polar initiation point.
Waymouth and Shaughnessy studied a dimethyl zir-
conocene/trimethylaluminum system capable of cyclizing
2-substituted 1,5-hexadienes (eq 2).10 The catalytic cycle
involved insertion of the least hindered olefin into the
zirconium-methyl bond followed by cyclization, with
subsequent trapping by trimethylaluminum. Oxidative
workup directly afforded alcohol products bearing a
methyl group as required by the catalytic system. Hin-
dered 1,6-heptadienes could not be cyclized utilizing this
(8) Watson, P. L.; Tebbe, F. N. U.S. Patent 4,965,386; Chem. Abstr.
1991, 114, 123331p.
(9) (a) Bailey, W. F.; Rossi, K. J . Am. Chem. Soc. 1989, 111, 765.
(b) Bailey, W. F.; Khanolkar, A. D.; Gavaskar, K. V. J . Am. Chem.
Soc. 1992, 114, 8053. (c) Bailey, W. F.; Ovaska, T. V. J . Am. Chem.
Soc. 1993, 115, 3080. (d) Rigollier, P.; Young, J . R.; Fowley, L. A.; Stille,
J . R. J . Am. Chem. Soc. 1990, 112, 9441.
(7) (a) Piers, W. E.; Shapiro, P. J .; Bunel. E. E.; Bercaw, J . E. Synlett
1990, 74. (b) Molander, G. A.; Hoberg, J . O. J . Am. Chem. Soc. 1992,
114, 3123.
(10) Shaughnessy, K. H.; Waymouth, R. M. J . Am. Chem. Soc. 1995,
117, 5873.
S0022-3263(97)02359-1 CCC: $15.00 © 1998 American Chemical Society
Published on Web 04/23/1998

Cyclization/Silylation of Hindered Dienes
J . Org. Chem., Vol. 63, No. 10, 1998 3387
protocol, and only a small number of 2-substituted 1,5-
dienes were investigated. In another report, Waymouth
and co-workers found that a similar zirconocene catalytic
system lacking a trapping agent could cyclopolymerize
2-methyl-1,5-hexadiene to provide a well-defined poly-
mer.11
oxidation protocol. Similar cyclization/silylation trans-
formations have also been developed using triene, ene-
yne, and dieneyne substrates.6f,14,17 By necessity, virtually
all of the research in this area has focused on monosub-
stituted olefins because of the diminished reactivity of
the “Cp*2YH” catalyst with more highly hindered double
bonds (eq 4).6g The goal of the current investigation was
to extend the cyclization/silylation reaction to 1,1-disub-
stituted olefins, allowing the formation of quaternary
centers in a stereoselective fashion.
An operationally related catalytic carbometalation
system was reported by Negishi and co-workers (eq 3).12
They revealed that dialkylaluminum chloride in the
presence of catalytic titanium(IV) isopropoxide mediated
the cyclization of a number of diene systems. The
organometallic products of the reaction were routinely
oxidized to alcohols for analysis. A number of substrates
were investigated, leading to a variety of monocyclic,
spirocyclic, and bicyclic systems. All of the substrates
studied, however, were hydrocarbons, leaving the ques-
tion of functional group tolerability unanswered. The
alkyl group installed in the reaction also limited the
generality of the process.
One of the attractive features of organolanthanide and
group 3 organometallic complexes is the ability to vary
their reactivity by changing the metal or by altering the
ligands on the metal. Larger metals and sterically less
crowded ligand substitution surrounding the metal in-
crease the open space about the catalytic center, thereby
increasing access to more sterically demanding alkenes.
Complexes incorporating metals with larger ionic radii
have been explored in the hydrogenation and hydrosi-
lylation of 1,1-disubstituted olefins.6e Thus, Cp*2SmCH-
(TMS)2 was utilized to increase reactivity toward a
variety of more highly hindered olefins. This enhanced
reactivity was attributed to the larger ionic radius of
Sm3+ as compared to that of Y3+ (1.09 versus 1.02 Å).18
Reactions times were long, however, and cyclization
events involving disubstituted alkenes remained elusive.
Marks and co-workers probed another catalyst varia-
tion in a recent hydrogenation study.2c They prepared a
silicon-bridged catalyst, Me2Si(Me3SiCp)[(-)-menthyl-
Cp]LnCH(TMS)2, with decreased substitution on the Cp
ligands that effected the efficient transformation of
2-methyl-1,5-hexadiene to 1,1-dimethylcyclopentane un-
der a hydrogen atmosphere. Although encouraging, they
did not attempt to terminate the process with silylation
nor was the synthetic scope of the reaction explored.
Cyclization/silylation reactions catalyzed by organo-
lanthanides or group 3 organometallics permit a number
of interesting transformations that allow a rapid increase
of molecular complexity in the transformation of simple
polyunsaturated substrates to cyclized products.6a,b,d,f,h,8
When presented with a suitable diene substrate, the
highly reactive yet incredibly selective precatalyst,
Cp*2YMe‚THF, is capable of selecting a single olefin site
for initial insertion.6b The complex then inserts the
remaining sterically available olefin, usually with high
diastereoselectivity, before σ-bond metathesis13 liberates
the silane product. In this manner monocyclic6b and
bicyclic systems14 bearing a variety of substitution pat-
terns have been generated. The utility of the silane
products is extended by oxidation protocols that convert
the carbon-silicon bond into an alcohol under acidic15
or basic16 conditions, allowing further functionalization.
The silane products are stable, allowing the unmasking
of an alcohol at a convenient time. The alcohol products
formed upon oxidation in this manner are structurally
complementary to those obtained by a carbometalation/
Resu lts a n d Discu ssion
The accepted catalytic cycle for the desired cyclization/
silylation is pictured in Scheme 1.6a,b The precatalyst
reacts with the silane via a σ-bond metathesis13 reaction
to generate an organolanthanide hydride, releasing the
alkyl group. This hydride then inserts the least hindered
olefin, placing the metal at the terminus of the carbon
chain. The hydrocarbyl formed undergoes intramolecular
olefin insertion (or multiple insertions) through a chair-
like transition structure before reacting with the silane
via σ-bond metathesis. This final step completes the
catalytic cycle and liberates the desired product.
(11) Kesti, M. R.; Waymouth, R. M. J . Am. Chem. Soc. 1992, 114,
3565.
(12) Kondakov, D. Y.; Wang, S.; Negishi, E. Tetrahedron Lett. 1996,
37, 3803.
(13) (a) Zinnen, H. A.; Pluth, J . J .; Evans, W. J . J . Chem. Soc., Chem.
Commun. 1980, 810. (b) Brothers, P. J . Prog. Inorg. Chem. 1981, 28,
1. (c) Evans, W. J .; Meadows, J . H.; Wayda, A. L.; Hunter, W. E.;
Atwood, J . L. J . Am. Chem. Soc. 1982, 104, 2008. (d) Schumann, H.;
Genthe, W. J . Organomet. Chem. 1981, 213, C7. (e) Marks, T. J . Inorg.
Chim. Acta 1987, 140, 1. (f) Thompson, M. E.; Baxter, S. M.; Bulls, A.
R.; Burger, B. J .; Nolan, M. C.; Santarsiero, B. D.; Schaefer, W. P.;
Bercaw, J . E. J . Am. Chem. Soc. 1987, 109, 203.
(15) (a) Tamao, K.; Ishida, N.; Tanaka, T.; Kumada, M. Organome-
tallics 1983, 2, 1649. (b) Bergens, S. H.; Noheda, P.; Whelan, J .;
Bosnich, B. J . Am. Chem. Soc. 1992, 114, 2121. (c) Taber, D. F.; Yet,
L.; Bhamidipati, R. S. Tetrahedron Lett. 1995, 36, 351. (d) Fleming, I.;
Hennings, R.; Plaut, H. J . Chem. Soc., Chem. Commun. 1984, 29. (e)
Fleming, I.; Sanderson, P. E. J . Tetrahedron Lett. 1987, 28, 4229. (f)
Fleming, I.; Winter, S. B. D. Tetrahedron Lett. 1993, 34, 7287.
(16) Smitrovich, J . H.; Woerpel, K. A. J . Org. Chem. 1996, 61, 6044.
(17) Retsch, W. H. Ph.D. Thesis, University of Colorado at Boulder,
1997.
(18) (a) Shannon, R. D.; Prewitt, C. T. Acta Crystallogr. 1969, B25,
925. (b) Shannon, R. D.; Prewitt, C. T. Acta Crystallogr. 1970, B26,
1046.
(14) Nichols, P. J . Ph.D. Thesis, University of Colorado at Boulder,
1997.

3388 J . Org. Chem., Vol. 63, No. 10, 1998
Molander et al.
that the Lewis acidic complex did not isomerize the
alkene substrates under the rigorous reaction conditions.
Utilizing this protocol, 1,1-disubstituted alkenes partici-
pated efficiently in the reactions. Alkyl chlorides could
be tolerated (entry 2), and quaternary centers were
generated with essentially complete stereochemical con-
trol (entries 3-5). Products possessing a variety of
structural motifs could be accessed, including spirocyclic
systems (entry 6). Although initial success was achieved
in cyclizing these more highly substituted alkenes, the
elevated temperatures and long reaction times required
prompted us to search for other, more reactive, catalyst
systems.
F igu r e 1. Perspective ORTEP drawing of the molecular
structure of [Me2Si(C5H3SiMe3)2YCl]2.
Sch em e 1
After a variety of potential complexes with larger
metals and/or less hindered ligands were prepared and
tested, the known20 and easily prepared21 metallocenes
[CpTMS2LnMe]2 (Ln ) Y, Lu) were selected as the pre-
catalysts of choice. In each case they provided the desired
cyclic products under milder conditions and in higher
yields than complex 1. These organometallic complexes
also exhibit attenuated air sensitivity when compared
with other organolanthanide alkyl complexes. In fact,
hydrosilylation reactions using this precatalyst have been
performed on the benchtop22 using standard techniques
for handling air-sensitive reagents.23
This metal/ligand/silane system proved to be extremely
versatile and adaptable to various substrate demands.
The ability to “tune” the reaction conditions for optimum
selectivity was illustrated in the reaction of 2-methyl-
1,5-hexadiene (eq 6). Cyclization of this diene with
[(CpTMS)2YMe]2 in the presence of phenylsilane led to high
yields of cyclized products 4a and 4b with 9:1 selectivity
in the initial olefin insertion step. When a precatalyst
with a slightly smaller metal was used, [(CpTMS)2LuMe]2,
the initial olefin insertion occurred exclusively at the
monosubstituted alkene.24 In this case, however, the
cyclized product was contaminated with substantial
amounts of uncyclized material 4c. To remedy this
situation, the silane was switched to the more hindered
methylphenylsilane. The additional alkyl group on the
silane slowed the σ-bond metathesis termination step
enough to allow complete cyclization prior to silylation.
This series of reactions effectively demonstrates how both
In an attempt to build on the study of Marks and co-
workers, a bridged complex [Me2Si(Me3SiCp)2YCH(TMS)2,
(1)] was prepared via a one-pot procedure (eq 5). Char-
acterization of the alkyl complex by NMR showed an
excess of resonance peaks, undoubtedly because of hin-
dered rotation about the carbon-metal bond.19 The NMR
spectra of the complex exhibited temperature-dependent
phenomena, but coalesence could not be achieved. All
attempts at obtaining crystalline material suitable for
X-ray analysis failed. The yttrocene chloride intermedi-
ate (2, Figure 1) could be isolated, however, and proved
more amenable to structural elucidation. The NMR
spectra of this material was consistent with a structure
in which the cyclopentadienyl ligands were bound in a
chelating mode. The X-ray structure of this dimer
showed that the desired ligand array had been prepared
and was attached to the metal in a manner analogous to
that previously observed for similar complexes.2c
(20) (a) Ballard, D. G. H.; Courtis, A.; Holton, J .; McMeeking, J .;
Pearce, R. J . Chem. Soc., Chem. Commun. 1978, 994. (b) Boskoboyni-
kov, A. Z.; Parshina, I. N.; Shestakova, A. K.; Butin, K. P.; Beletskaya,
I. P.; Kuz′mina, L. G.; Howard, J . A. K. Organometallics 1997, 16, 4041.
(21) Prepared by a modification of the procedure given in ref 20b:
KCpTMS (6 mmol) and LnCl3 (3 mmol) were heated at reflux in THF
for 4 h. The solvent was removed in vacuo and replaced with Et2O.
MeLi (2.15 mL of a 1.4 M solution in Et2O, 3 mmol) was added at -78
°C, and the reaction was warmed to room temperature. After the
solution was stirred for 4 h, the solvent was removed and the solids
were extracted with hexanes. Decantation and crystallization from
hexanes yielded the desired organometallics.
Alkyl complex 1 was used to effect the cyclization/
silylation of a variety of hindered dienes (Table 1). This
initial complex proved to be catalytically active at high
temperatures over the long reaction periods required for
the reactions to proceed to completion. It is also notable
(22) Markus Keitsch, unpublished results.
(23) Brown, H. C. Organic Syntheses via Boranes; Wiley: New York,
1975.
(19) Schaverien, C. J .; Nesbitt, G. J . J . Chem. Soc., Dalton Trans.
1992, 157.
(24) The ionic radii of Lu3+ and Y3+ are 0.97 and 1.02 Å respectively.
See ref 18.

Cyclization/Silylation of Hindered Dienes
J . Org. Chem., Vol. 63, No. 10, 1998 3389
Ta ble 1. Cycliza tion /Silyla tion Rea ction s Ca ta lyzed
by Me2Si(C5H3SiMe3)2YCH(TMS)2 (1)
Ta ble 2. Cycliza tion /Silyla tion Rea ction s Ca ta lyzed by
[(Cp TMS)2YMe]2
the catalyst and the silane can be simultaneously ad-
justed to effect desired outcomes in reactions of interest.
The utility of a successful catalytic system would be
enhanced if it tolerated a wide variety of common organic
functional groups (or their protected versions), as well
as a number of substitution patterns. To assess these
factors, several diene substrates were prepared by stan-
dard literature methods. The effects of varying substit-
uents and substitution patterns in cyclizations of 1,5-
dienes are displayed in Table 2. Entries 1 and 4
demonstrate the high diastereoselectivity possible in the
formation of a quaternary center with this transforma-
tion. In each of these cases a single product isomer was
generated, the stereochemistry of which is best rational-
ized by a chairlike transition structure (see Scheme 1)
that places the allylic substituent in an equatorial
orientation. The stereochemistry of the product was
confirmed by NOE difference spectroscopy. Substrate 21
(entry 2), in which the substituent is one carbon closer
to the unhindered olefin, provided an inseparable mixture
of diastereomers and regioisomers. The erosion of dia-
stereoselectivity has previously been noted in the cycliza-
tion of 4-substituted heptadienes with an organoyttrium
complex.6b The minor regioisomeric product comes from
insertion of the disubstituted olefin first followed by ring
closure and silylation. This occurs because the presence
of substitution allylic to the monosubstituted olefin
sterically shields it, making the insertion of the disub-
stituted olefin somewhat competitive. The identity of the
major isomer was elucidated by oxidation of the silane
products to the corresponding alcohols followed by chro-
matographic separation and NOE analysis of the major
alcohol 23.
The cyclization protocol was extended to dienes where
both double bonds were disubstituted. Symmetrical
diene 7 reacted to afford a single product (entry 5). The
stereochemistry was as expected and proven by conver-
sion to the alcohol 9 and comparison to literature data.10
The issue of minimum catalyst loading necessary to
convert substrates efficiently to products is an important
one and has been addressed in the current study on a
reasonably large-scale reaction. In a typical experiment,

3390 J . Org. Chem., Vol. 63, No. 10, 1998
Molander et al.
Ta ble 3. Cycliza tion /Silyla tion Rea ction s In volvin g
Mu ltip le Bon d In ser tion s
Sch em e 2
approximately 0.5 mmol of substrate was exposed to 5
mol % of the precatalyst, a convenient amount to weigh.
To determine the minimum catalyst loading possible, the
amount of 7 was increased while using very small
amounts of the catalyst. On a 20 mmol scale with as
little as 0.5 mol % catalyst, the reaction proceeded
smoothly (in virtually the same reaction time as small-
scale reactions loaded at 5 mol %) to provide good yields
(∼80%) of the desired product.
A transannular cyclization was conducted to provide
bridged bicyclic product 27 (entry 6). The yield of this
transformation was reduced by the isomerization of one
exocyclic double bond into the ring, preventing cycliza-
tion. Several other metallocene complexes were used in
attempts to accomplish this transformation, but in each
case the yield of the desired bridgehead bicyclic product
was very low. For example, the yield of the bicyclo[3.3.1]
system was <10% using complex 1 under all conditions
attempted.
membered ring, and the intermediate monocyclic hydro-
carbyl is persistent enough to form another ring in a
spirocyclic fashion before the trapping event to afford the
observed product 18 in good yield.
Entries 2-4 explore another scenario for multiple
insertions, building additional rings onto an existing
structure. In each of these cases the reaction begins with
the insertion of the least hindered double bond. In
substrate 37 the initial hydrocarbyl intermediate formed
then has a choice of inserting the 1,1-disubstituted olefin
to form a five-membered ring or the less hindered
monosubstituted double bond to form a six-membered
ring. As outlined in Table 3, the hindered cyclization was
competitive, and a mixture of propellane (38) and un-
characterized isomers assumed to be spirocyclic (39) was
obtained. To make the first cyclization event more
selective, substrate 40 was prepared in which the com-
plex must choose between insertion of two 1,1-disubsti-
tuted olefins: one forming a cyclopentane, the other a
cyclohexane. The observed products indicate that the
subsequent cyclization passed through the five-ring
manifold, with a small amount of material being trapped
before any cyclization events occur. Products 38 and 41
were composed of inseparable mixtures of diastereomers,
epimeric at the silane-bearing substituent. Substrate 43
was designed to eliminate this mixture, as it cyclized to
symmetrical propellane 44 in good yield.
A number of bicyclic products were generated by the
ring closure of pendant alkenyl side chains onto an
existing ring. A wide variety of R-allyl methylenecyclo-
alkanes were found to cyclize efficiently to form bicy-
clo[3.3.0] and bicyclo[4.3.0] systems (entries 7-12). The
stereochemistry of the ring juncture in one of these
examples was determined by the conversion of silane 13
to the corresponding carboxamide 16 and comparison
with literature data for this reported compound (Scheme
2).25 The generation of cis-fused products complements
the formation of trans-bicyclo[3.3.0] systems developed
previously using similar group 3 metallocene complexes.14
Heteroatoms were generally tolerated, although reac-
tion times were lengthened because of Lewis base coor-
dination to the metal center. In the extreme case of
unhindered ether 30 (entry 10), heating was required to
obtain complete reaction in a reasonable time. This
depression of catalytic turnover has previously been
observed in olefin hydrogenation.2a,e The effect of Lewis
bases on catalytic activity is not ubiquitous, however, as
Cp*2YMe‚THF is more efficient as a precatalyst for diene
cyclization/silylation than the ether-free complex Cp*2-
YCH(TMS)2.6b
The intramolecular insertion of multiple double bonds
before the trapping event has been effectively exploited
for monosubstituted diene systems. In properly designed
substrates, single diastereomers of complex bicyclic si-
lanes were obtained.14 To investigate the possibility of
multiple olefin insertions exploiting the current catalyst’s
capabilities, several triene substrates were prepared
(Table 3). In substrate 17, the complex initially inserted
one of the monosubstituted olefins before cyclizing onto
the 1,1-disubstituted olefin (entry 1). This first ring-
forming step is selective for the formation of the five-
The cyclization of bis(monosubstituted) dienes was also
explored to assess the generality of the current catalytic
system. Five- and six-membered rings were formed in
this manner. However, methylphenylsilane was required
in cyclohexane generation to slow the trapping event
relative to intramolecular insertion (eq 7). In experi-
ments combining 1,6-heptadiene and phenylsilane, the
linear disilylated product dominated. Also interesting
was the successful cyclization of 3-substituted 1,6-hep-
tadienes, a substitution pattern found to be problematic
in an earlier study with a different catalyst.6b The allylic
substitution was sufficient to direct the complex to the
less hindered olefin for initial insertion. In the cycliza-
tion of 49, the product derived from initial insertion of
the allylically substituted olefin was detected, eroding the
yield of 50. The trans stereochemistry of products 50 and

Cyclization/Silylation of Hindered Dienes
J . Org. Chem., Vol. 63, No. 10, 1998 3391
Ta ble 4. Su bstr a tes P r ovid in g P r ed om in a n tly
Un cyclized P r od u cts
53 was determined by the oxidation of the silanes to
known alcohols 51 and 54, respectively.26,27
The present limitations of this protocol are shown in
Table 4. Substrate 55 was designed to provide a bicy-
clo[4.4.0] product. Monocyclic products such as 56 were
obtained rapidly and in good yield under all conditions
attempted, including those where PhMeSiH2 was utilized
as a terminating agent (entry 1). This result mirrors the
dimethylzirconocene results of Waymouth discussed ear-
lier, where hindered cyclohexane formation was not
observed.10 It was also discovered that isopropyl substi-
tution on the hindered olefin prevented cyclization (entry
2). The insertion of one methylene unit between the
double bond and the branch point allowed approximately
half of the material to cyclize (entry 3), while two
methylene units allowed the cyclized product to be
isolated in good yield (entry 4). 3-Allylcyclohexene (64)
was prepared in hopes that the catalyst would form a
bicyclo[4.3.0] product, but uncyclized monosilylated prod-
uct was obtained exclusively. Substrate 66 contained a
quaternary vinyl group that was previously found not to
cyclize using other catalysts.14 We exposed this to the
current reaction conditions with the expectation that the
less hindered catalyst would provide a different result.
The material obtained, however, was spectroscopically
identical to the product previously generated (entry 6).
Exp er im en ta l Section
All experiments involving the organometallic complexes
were performed with careful exclusion of oxygen and moisture
in flame-dried Schlenk-type glassware interfaced to a vacuum-
argon double manifold,29 or in
a nitrogen-filled Vacuum
Atmospheres glovebox. The cyclohexane and benzene-d6 used
as solvents in the catalytic reactions were distilled from Na/
benzophenone under argon and stored in the glovebox. All
substrates were distilled and degassed before use. 2-Methyl-
1,5-hexadiene, 2,5-dimethyl-1,5-hexadiene, 1,5-hexadiene, 1,6-
heptadiene, and phenylsilane were purchased from Aldrich.
Methylphenylsilane was purchased from United Chemical
Technologies. Substrates 12,6g 26,30 64,31 and 6614 were
prepared according to literature methods.
[Me2Si(Me3SiCp )2YCH(TMS)2] (1). Me2Si(Me3SiCp)2Li2
(0.861 g, 2.5 mmol) and YCl3 (0.490 g, 2.5 mmol) were weighed
into a Schlenk flask and cooled to -78 °C, and 75 mL of THF
was added. The mixture was allowed to warm to room
temperature and stirred for 12 h. After cooling, the solvent
was removed in vacuo and replaced with Et2O. Next, the
mixture was cooled to -78 °C, and LiCH(TMS)2 (0.415 g, 2.5
mmol) was added slowly. The mixture was allowed to warm
to room temperature and stirred overnight. The solvent was
removed in vacuo and the residue extracted with hexanes. The
supernatant was decanted and concentrated for crystallization
at -30 °C. A light tan solid (1.11 g, 1.92 mmol, 77%) was
obtained whose NMR was complex and exhibited temperature
dependent phenomena. All attempts at obtaining crystals
suitable for X-ray analysis failed.
Con clu sion s
The cyclization/silylation of dienes has been extended
to 1,1-disubstituted olefins by the development of
[(CpTMS)2LnMe]2 complexes as precatalysts. This class
of organometallics demonstrated enhanced reactivity
toward more highly hindered alkenes, and thus catalyst
loadings as low as 0.5 mol % can be utilized on large-
scale reactions. Despite their high reactivity, the com-
plexes described herein exhibit surprising stability to air.
They are thus much easier to handle than previously
developed catalysts from the same family. A variety of
monocyclic, bicyclic, spirocyclic, and propellane products
were generated efficiently, diastereoselectively, and un-
der mild conditions. Importantly, quaternary stereo-
centers were created with virtually complete stereochem-
ical control. The cyclized silanes were synthesized by an
atom economical process,28 and this, plus the fact that
reactions are performed in hydrocarbon solvents, facili-
tates isolation of the desired products. The silane moiety
generated is stable, allowing unmasking to the corre-
sponding alcohol at a convenient time. These alcohols
are complementary to those derived from analogous
carbometalation/cyclization procedures.
[Me2Si(Me3SiCp )2YCl]2 (2). A Schlenk flask was charged
with 35 mL of THF and cooled to -78 °C before Me2Si(Me3-
SiCp)2Li2 (0.344 g, 1.0 mmol) and YCl3 (0.195 g, 1.0 mmol) were
added slowly. The mixture was warmed to reflux and stirred
for 6 h. After cooling, the solvent was removed in vacuo and
the solid residue extracted with 50 mL of hexanes. The
supernatant was decanted, concentrated slightly, and cooled
overnight for crystallization. The white crystals generated
(0.090 g, 0.10 mmol, 20%) were dried and submitted for X-ray
(25) Thompson, H. W.; Muccino, R. R. J . Am. Chem. Soc. 1972, 94,
1183.
(26) Rieke, R. D.; Xiong, H. J . Org. Chem. 1991, 56, 3109.
(27) Pelter, A.; Vaughn-Villiams, G. F.; Rosser, R. M. Tetrahedron
1993, 49, 3007.
(28) (a) Trost, B. M. Angew. Chem., Int. Ed. Engl. 1995, 34, 259. (b)
Trost, B. M. Science 1991, 254, 1471.
(29) Shriver, D. F.; Drezdzon, M. A. The Manipulation of Air-
Sensitive Compounds, 2nd ed.; Wiley: New York, 1986.

3392 J . Org. Chem., Vol. 63, No. 10, 1998
Molander et al.
analysis: 1H NMR (400 MHz, C6D6) δ 7.00 (t, J ) 2.2 Hz, 2H),
6.62 (t, J ) 2.0 Hz, 2H), 6.33 (t, J ) 2.2 Hz, 2H), 0.78 (s, 3H),
0.42 (s, 3H), 0.36 (s, 18H); 13C NMR (100 MHz, C6D6) δ 135.37,
123.92, 121.92, 120.86, 120.43, 0.14, -2.35, -6.00.
Workup and purification by flash chromatography followed by
Kugelrohr distillation afforded the title compound in 79%
yield: ot 75 °C/0.05 mmHg; 1H NMR (400 MHz, CDCl3) δ
7.58-7.55 (m, 2H), 7.39-7.31 (m, 3H), 4.34-4.27 (m, 2H),
Cycliza tion s Usin g 1 a s th e P r eca ta lyst: 1-Meth yl-1-
[(p h en ylsilyl)m eth yl]cyclop en ta n e (4, R ) H) (Gen er a l
P r oced u r e for Cycliza tion /Silyla tion Usin g 1). The pre-
catalyst (5 mg, 8.6 µmol) was dissolved in cyclohexane (0.5
mL) in the glovebox. Next, 2-methyl-1,5-hexadiene was added
(26 mg, 0.27 mmol) followed by phenylsilane (32 mg, 0.29
mmol). This solution was transferred to a tube with a Teflon
screw valve which was sealed, and the tube was removed from
the glovebox. This tube was heated to 90 °C with stirring for
12 h. After cooling, the reaction vessel was opened to the air
and the contents were filtered through a small plug of Florisil.
The filtrate was concentrated and purified by flash chroma-
tography followed by Kugelrohr distillation to yield a colorless
1.70-1.49 (m, 7H), 1.45-1.31 (m, 9H), 1.02-0.96 (m, 1H); 13
C
NMR (100 MHz, CDCl3) δ 135.2, 133.6, 129.3, 127.9, 46.5, 42.6,
38.2, 32.6, 28.2, 25.8, 22.1, 21.9, 21.2, 20.5; IR (neat) 3068,
3051, 3000, 2923, 2132 cm-1; HRMS calcd for C16H24Si
244.1647, found 244.1645; LRMS (EI+) m/z 244 (7), 166 (100),
137 (20), 123 (24), 121 (54), 107 (96). Anal. Calcd for
C
16H24Si: C, 78.61; H, 9.90. Found: C, 78.84; H, 9.98.
2-[(P h en ylsilyl)m eth yl]sp ir o[4.4]n on a n e (18) was pre-
pared from 17 according to the general experimental procedure
for cyclization/silylation using 1. The reaction was found to
be complete by GC analysis after 24 h at 90 °C. Workup and
purification by flash chromatography followed by Kugelrohr
distillation afforded the title compound in 68% yield: ot 90
1
1
oil (42 mg, 76%): ot 50 °C/0.05 mmHg; Rf 0.59 (hexanes); H
°C/0.05 mmHg; Rf 0.53 (hexane); H NMR (400 MHz, CDCl3)
NMR (400 MHz, CDCl3) δ 7.57-7.55 (m, 2H), 7.37-7.31 (m,
3H), 4.33 (t, J ) 4.1 Hz, 2H), 1.65-1.59 (m, 4H), 1.59-1.40
(m, 4H), 1.15 (t, J ) 4.1 Hz, 2H), 1.04 (s, 3H); 13C NMR (100
MHz, CDCl3) δ 135.2, 133.5, 129.4, 127.9, 41.8, 41.2, 28.1, 24.8,
24.2; IR (neat) 3068, 2951, 2870, 2135 cm-1; HRMS calcd for
δ 7.57-7.55 (m, 2H), 7.40-7.32 (m, 3H), 4.28 (t, J ) 4.0 Hz,
2H), 2.11-2.00 (m, 1H), 1.90-1.82 (m, 1H), 1.73 (dd, J ) 12.3,
7.2 Hz, 1H), 1.60-1.50 (m, 5H), 1.48-1.34 (m, 5H), 1.29-1.19
(m, 1H), 1.13 (dd, J ) 12.3, 9.9 Hz, 1H), 1.07-1.03 (m, 2H);
13C NMR (100 MHz, CDCl3) δ 135.20, 133.02, 129.42, 127.92,
50.66, 48.99, 40.38, 40.14, 38.86, 36.09, 34.96, 24.39, 24.36,
17.66; IR (neat) 3067.7, 2940.0, 2855.8, 2132.5 cm-1; LRMS
(EI+) m/z 244 (3), 187 (11), 166 (97), 137 (35), 124 (79), 121
(90), 107 (100), 105 (49). Anal. Calcd for C16H24Si: C, 78.62;
H, 9.90. Found: C, 78.29; H, 9.76.
C
13H20Si 204.1334, found 204.1349; LRMS (EI+) m/z 204 (2),
189 (7), 126 (78), 107 (100), 105 (51), 97 (34). Anal. Calcd for
C
13H20Si: C, 76.40; H, 9.86. Found: C, 76.26; H, 9.85.
1-(6-Ch lor oh e xyl)-1-[(p h e n ylsilyl)m e t h yl]cyclop e n -
ta n e (6) was prepared from 5 according to the general
experimental procedure for cyclization/silylation using 1. The
reaction was found to be complete by GC analysis after 2 h at
110 °C. Workup and purification by Kugelrohr distillation
afforded the title compound in 66% yield: ot 130 °C/0.05
mmHg; 1H NMR (400 MHz, CDCl3) δ 7.57-7.54 (m, 2H), 7.39-
7.30 (m, 3H), 4.29 (t, J ) 4.1 Hz, 2H), 3.50 (t, J ) 6.8 Hz, 2H),
1.78-1.67 (m, 2H), 1.64-1.53 (m, 4H), 1.45-1.32 (m, 8H),
1.30-1.16 (m, 4H), 1.11 (t, J ) 4.1 Hz, 2H); 13C NMR (100
MHz, CDCl3) δ 135.2, 133.4, 129.4, 127.9, 45.2, 44.3, 41.0, 40.1,
32.6, 29.6, 26.9, 24.9, 24.3, 21.5; IR (neat) 3067.7, 2932.0,
2132.8 cm-1; LRMS (EI+) m/z 308 (1), 189 (100), 161 (80), 107
(92), 105 (72). Anal. Calcd for C18H29ClSi: C, 70.20; H, 9.49.
Found: C, 70.46; H, 9.73.
(1R*,3R*)-1,3-Dim et h yl-1-[(p h en ylsilyl)m et h yl]cyclo-
p en ta n e (8) was prepared from 7 according to the general
experimental procedure for cyclization/silylation using 1. The
reaction was found to be complete by GC analysis after 48 h
at 90 °C. Workup and purification by Kugelrohr distillation
afforded the title compound in 58% yield: ot 58 °C/0.01 mmHg;
1H NMR (400 MHz, CDCl3) δ 7.56-7.54 (m, 2H), 7.38-7.30
(m, 3H), 4.31 (t, J ) 4.1 Hz, 2H), 2.09-2.03 (m, 1H), 1.84-
1.72 (m, 2H), 1.51-1.48 (m, 2H), 1.24-1.16 (m, 1H), 1.14 (t, J
) 4.1 Hz, 2H), 1.10 (s, 3H), 1.03-0.99 (m, 1H), 0.96 (d, J )
6.4 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 135.2, 133.4, 129.3,
127.9, 50.8, 42.3, 41.4, 34.0, 33.8, 30.3, 25.4, 21.4; IR (neat)
3068.5, 2949.4, 2866.5, 2135.1, 1455.4 cm-1; LRMS (EI+) m/z
218 (4), 203 (33), 189 (36), 147 (62), 140 (70), 107 (79), 105
(74), 97 (91), 81 (100). Anal. Calcd for C14H22Si: C, 76.99; H,
10.15. Found: C, 76.82; H, 10.30.
Cycliza tion s u sin g [Cp TMS2Ln Me]2 a s th e P r eca ta lyst:
1-Meth yl-1-[(m eth ylp h en ylsilyl)m eth yl]cyclop en ta n e (4,
R ) Me) (Rep r esen ta tive P r oced u r e for th e NMR Cy-
cliza tion /Silyla tion Rea ction Usin g [Cp TMS2Ln Me]2). In
a nitrogen filled glovebox 0.077 g (0.63 mmol) of methylphen-
ylsilane was added to 0.010 g (4.3 mol %) of the precatalyst
[CpTMS2LuMe]2 dissolved in 0.7 mL of C6D6. Next, 0.048 g (0.50
mmol) of 2-methyl-1,5-hexadiene was added and the solution
was transferred to a Teflon-valved NMR tube before being
heated to 80 °C. The progress of the reaction was checked
periodically by NMR, and the reaction was found to be
complete after 12 h. The reaction mixture was next diluted
with hexanes and filtered through a plug of Florisil. The
solution was concentrated by rotary evaporation and purified
by Kugelrohr distillation to yield 0.087 g (0.40 mmol, 80%
yield) of 4 as a colorless oil: ot 70 °C/0.03 mmHg; 1H NMR
(500 MHz, CDCl3) δ 7.54-7.51 (m, 2H), 7.35-7.31 (m, 3H),
4.45 (hextet, J ) 3.8 Hz, 1H), 1.64-1.52 (m, 4H), 1.42-1.36
(m, 4H), 1.12 (dd, J ) 14.8, 3.0 Hz, 1H), 1.00 (s, 3H), 0.99 (dd,
J ) 14.6, 4.2 Hz, 1H), 0.34 (d, J ) 3.8 Hz, 3H); 13C NMR (125
MHz, CDCl3) δ 137.92, 134.26, 128.98, 127.78, 42.22, 42.21,
41.54, 28.65, 28.32, 24.14, 24.08, -3.36; IR (neat) 3068.0,
2952.3, 2870.4, 2118.8 cm-1; HRMS calcd for C14H22Si 218.1491,
found 218.1525; LRMS (EI+) m/z 218 (1), 203 (2), 161 (8), 140
(23), 121 (100). Anal. Calcd for C14H22Si: C, 76.99; H, 10.15.
Found: C, 77.13; H, 10.29.
(1R*,2R*)-1-Met h yl-2-p h en yl-1-[(p h en ylsilyl)m et h yl]-
cyclop en ta n e (20) (Rep r esen ta tive P r oced u r e for th e
Ca ta lytic Cycliza tion /Silyla tion Rea ction Usin g [Cp TMS
-
2
1-[(P h en ylsilyl)m eth yl]-cis-bicyclo[3.3.0]octan e (11) was
prepared from 10 according to the general experimental
procedure for cyclization/silylation using 1. The reaction was
found to be complete by GC analysis after 14 h at 90 °C.
Workup and purification by Kugelrohr distillation afforded the
YMe]2 a s th e P r eca ta lyst). In a nitrogen-filled glovebox
0.066 g (0.61 mmol) of phenylsilane was added to 0.005 g (2.7
mol %) of the precatalyst [CpTMS2YMe]2 dissolved in 0.5 mL of
cyclohexane. Next, 0.083 g (0.48 mmol) of 3-phenyl-2-methyl-
1,5-hexadiene (19) was added and the solution was stirred at
ambient temperature. Small aliquots were removed periodi-
cally for GC analysis, and the reaction was found to be
complete after 12 h. After being removed from the glovebox,
the reaction mixture was diluted with hexanes and filtered
through a plug of Florisil. The solution was concentrated by
rotary evaporation and purified by flash chromatography
followed by Kugelrohr distillation to yield 0.124 g (0.44 mmol,
92% yield) of 20 as a colorless oil: ot 105 °C/0.01 mmHg; Rf
1
title compound in 58% yield: ot 70 °C/0.05 mmHg; H NMR
(500 MHz, CDCl3) δ 7.58-7.55 (m, 2H), 7.39-7.32 (m, 3H),
4.33 (t, J ) 4.17 Hz, 2H), 2.03-1.97 (m, 1H), 1.82-1.75 (m,
2H), 1.59-1.46 (m, 8H), 1.26-1.20 (m, 4H); 13C NMR (125
MHz, CDCl3) δ 135.19, 133.46, 129.33, 127.91, 52.44, 51.87,
41.63, 34.34, 25.88, 25.39; IR (neat) 3067.8, 2940.3, 2859.9,
2133.4 cm-1; LRMS (EI+) m/z 230 (9), 173 (8), 152 (100), 123
(36), 121 (27), 107 (74), 105 (38). Anal. Calcd for C15H22Si:
C, 78.19; H, 9.62. Found: C, 78.16; H, 9.58.
1
0.34 (hexanes); H NMR (500 MHz, CDCl3) δ 7.55-7.51 (m,
1-[(P h en ylsilyl)m eth yl]-cis-bicyclo[4.3.0]n on a n e (13)
was prepared from 12 according to the general experimental
procedure for cyclization/silylation using 1. The reaction was
found to be complete by GC analysis after 24 h at 90 °C.
2H), 7.39-7.31 (m, 3H), 7.29-7.25 (m, 2H), 7.22-7.19 (m, 3H),
4.35 (td, J ) 5.9, 2.8 Hz, 1H), 4.31 (td, J ) 5.9, 2.8 Hz, 1H),
2.79-2.75 (m, 1H), 2.10-1.98 (m, 2H), 1.84-1.64 (m, 4H),
1.18-1.13 (m, 1H), 1.04-1.00 (m, 1H), 0.76 (s, 3H); 13C NMR

Cyclization/Silylation of Hindered Dienes
J . Org. Chem., Vol. 63, No. 10, 1998 3393
(125 MHz, CDCl3) δ 141.32, 135.22, 133.25, 129.41, 128.95,
127.93, 127.70, 126.12, 58.33, 44.50, 40.58, 29.44, 24.13, 22.50,
21.26; IR (neat) 3066.7, 3025.9, 2955.4, 2873.0, 2134.2, 1601.0
cm-1; HRMS calcd for C19H24Si 280.1647, found 280.1649;
LRMS (EI+) m/z 280 (21), 238 (9), 202 (30), 189 (21), 183 (22),
147 (36), 107 (100), 105 (69), 91 (71).
127.46, 127.35, 83.48, 44.45, 36.59, 31.74, 27.11, 22.32, 21.15,
19.43, 19.22; IR (neat) 3069.3, 3049.3, 2998.1, 2958.9, 2134.9,
1589.4 cm-1; HRMS calcd for C25H29OSi2 (M - t-Bu) 401.1757,
found 401.1761; LRMS (EI+) m/z 401 (21), 305 (100), 227 (60),
199 (58), 107 (27), 105 (24). Anal. Calcd for C29H38OSi2: C,
75.92; H, 8.35. Found: C, 76.06; H, 8.73.
(1R*,2S*)-1-Met h yl-3-p h en yl-3-[(p h en ylsilyl)m et h yl]-
cyclop en ta n e (22) was prepared from 21 according to the
general experimental procedure for cyclization/silylation using
[CpTMS2YMe]2 as the precatalyst. The reaction was found to
be complete by GC analysis after 12 h at room temperature.
Workup and purification by flash chromatography followed by
Kugelrohr distillation afforded the title compound in 95%
yield: ot 120 °C/0.05 mmHg; Rf 0.45 (hexanes); 1H NMR (500
MHz, CDCl3) δ 7.57-7.53 (m, 2H), 7.38-7.33 (m, 3H), 7.28-
7.25 (m, 2H), 7.20-7.18 (m, 2H), 7.16-7.13 (m, 1H), 4.37-
7.32 (m, 2H), 3.22-3.15 (m, 1H), 2.19-2.10 (m, 1H), 1.96-
1.92 (m, 1H), 1.77-1.69 (m, 2H), 1.64-1.58 (m, 2H), 1.27-
1.25 (m, 2H), 1.15 (s, 3H); 13C NMR (125 MHz, CDCl3) δ 146.45,
135.22, 133.19, 129.44, 128.27, 127.97, 127.03, 125.71, 51.16,
44.53, 41.92, 41.42, 33.68, 29.12, 26.45; IR (neat) 3066.9,
3025.3, 2949.0, 2866.2, 2133.7, 1601.9 cm-1; LRMS (EI+) m/z
280 (4), 202 (22), 107 (100), 91 (57). Anal. Calcd for
(1R*,3R*)-1,3-Dim et h yl-1-[(p h en ylsilyl)m et h yl]cyclo-
p en ta n e (8) was prepared from 7 according to the general
experimental procedure for NMR cyclization/silylation using
[CpTMS2YMe]2 as the precatalyst. The reaction was found to
be complete by NMR after 12 h at 90 °C. Workup and
purification by Kugelrohr distillation afforded the title com-
pound in 92% yield. The spectra of this material were identical
to those reported for cyclization using 1 as the precatalyst.
(1R*,3R*)-1,3-Dim eth yl-1-cyclopen tan em eth an ol (9) was
prepared from 8 according to the general procedure for silane
oxidation. The spectra of the material obtained were similar
to the data reported in the literature for the title compound.10
1-[(P h en ylsilyl)m eth yl]bicyclo[3.3.1]n on a n e (27) was
prepared from 26 according to the general experimental
procedure for cyclization/silylation using [CpTMS2YMe]2 as the
precatalyst. The reaction was found to be complete by GC
analysis after 20 h at room temperature. Workup and
purification by flash chromatography followed by Kugelrohr
distillation afforded the title compound in 49% yield: ot 100
C
19H24Si: C, 81.36; H, 8.62. Found: C, 81.48; H, 8.81.
(1R *,2S *)-1-Me t h yl-3-p h e n yl-1-cyclop e n t a n e m e t h a -
1
°C/0.05 mmHg; H NMR (500 MHz, CDCl3) δ 7.56-7.54 (m,
n ol (23) (Rep r esen ta tive P r oced u r e for th e Oxid a tion of
Sila n es).15b The silane 22 (0.0598 g, 0.213 mmol) was
dissolved in CHCl3 (3 mL) and cooled to 0 °C before the
addition of HBF4‚OEt2 (0.100 g, 0.62 mmol) via pipet. The
mixture was next stirred for 1 h before the volitiles were
removed in vacuo. The residue was dissolved in 3 mL of 1:1
MeOH:THF, and KF (0.062 g, 1.07 mmol), KHCO3 (0.128 g,
1.28 mmol), and 0.5 mL of 30% H2O2 were added. The mixture
was next heated at reflux for 12 h, during which a white
precipitate formed. After cooling, the mixture was concen-
trated in vacuo and transferred onto 10 mL of saturated
aqueous NaCl. The aqueous layer was extracted (3×) with
50 mL portions of Et2O. The combined organic layers were
dried over Na2SO4 and concentrated to yield a colorless oil.
Purification by flash chromatography yielded a small amount
of the major isomer pure along with a larger fraction consisting
of a mixture of isomers (total yield: 0.0295 g, 0.139 mmol,
65%). The major isomer was subjected to NOE analysis to
determine the stereochemistry: Rf 0.36 (20% EtOAc/hexanes);
1H NMR (500 MHz, CDCl3) δ 7.28-7.22 (m, 4H), 7.18-7.14
(m, 1H), 3.47 and 3.45 (AB-system, J AB ) 10.42 Hz, 2H), 3.19
(tt, J ) 11.1, 7.1 Hz, 1H), 2.14-2.07 (m, 1H), 1.82-1.76 (m,
2H), 1.73-1.64 (m, 1H), 1.60-1.55 (m, 1H), 1.46-1.40 (m, 2H),
1.11 (s, 3H); 13C NMR (125 MHz, CDCl3) δ 145.43, 128.26,
127.00, 125.86, 71.97, 44.76, 44.68, 43.75, 36.02, 34.08, 25.30;
IR (neat) 3354.1, 3082.8, 3060.3, 3026.4, 2947.9, 2865.7, 1601.9
cm-1; HRMS calcd for C13H18O 190.1358, found 190.1385;
LRMS (EI+) m/z 190 (32), 172 (14), 159 (50), 91 (100). Anal.
Calcd for C13H18O: C, 82.06; H, 9.53. Found: C, 81.98; H, 9.57.
1-(6-Ch lor oh e xyl)-1-[(p h e n ylsilyl)m e t h yl]cyclop e n -
ta n e (6) was prepared from 5 according to the general exper-
imental procedure for cyclization/silylation using [CpTMS2YMe]2
as the precatalyst. The reaction was found to be complete by
GC analysis after 1 h at room temperature. Workup and
purification by Kugelrohr distillation afforded the title com-
pound in 79% yield. The spectra of this material were identical
to those reported for cyclization using 1 as the precatalyst.
(1R*,2R*)-2-(ter t-Bu t yld ip h en ylsilyloxy)-1-m et h yl-1-
[(p h en ylsilyl)m eth yl]cyclop en ta n e (25) was prepared from
24 according to the general experimental procedure for cy-
clization/silylation using [CpTMS2YMe]2 as the precatalyst. The
reaction was found to be complete by GC analysis after 16 h
at room temperature. Workup and purification by flash
chromatography afforded the title compound in 74% yield: 1H
NMR (500 MHz, CDCl3) δ 7.74-7.66 (m, 4H), 7.50-7.48 (m,
2H), 7.43-7.32 (m, 9H), 4.30-4.23 (m, 2H), 3.79 (t, J ) 6.9
Hz, 1H), 1.65-1.48 (m, 4H), 1.42-1.30 (m, 2H), 1.18 (ddd, J
) 14.6, 5.7, 3.0 Hz, 1H), 1.10 (s, 3H), 1.09 (s, 9H), 0.75 (ddd,
J ) 14.6, 5.5, 2.6 Hz, 1H); 13C NMR (125 MHz, CDCl3) δ
136.02, 135.97, 135.16, 134.95, 134.33, 129.49, 129.40, 127.87,
2H), 7.36-7.30 (m, 3H), 4.33 (t, J ) 4.3 Hz, 2H), 1.93-1.88
(m, 3H), 1.70 (dd, J ) 13.4, 6.0 Hz, 2H), 1.64-1.49 (m, 6H),
1.42-1.36 (m, 4H), 0.93 (t, J ) 4.3 Hz, 2H); 13C NMR (100
MHz, CDCl3) δ 135.21, 133.68, 129.28, 127.89, 43.50, 39.06,
32.10, 30.77, 29.68, 29.55, 22.87; IR (neat) 3067.6, 2987.1,
2898.3, 2843.6, 2133.4 cm-1; LRMS (EI+) m/z 244 (6), 201 (91),
173 (81), 166 (93), 107 (100). Anal. Calcd for C16H24Si: C,
78.62; H, 9.90. Found: C, 78.99; H, 10.14.
1-[(P h en ylsilyl)m eth yl]-cis-bicyclo[3.3.0]octan e (11) was
prepared from 10 according to the general experimental
procedure for cyclization/silylation using [CpTMS2YMe]2 as the
precatalyst. The reaction was found to be complete by GC
analysis after 1 h at room temperature. Workup and purifica-
tion by Kugelrohr distillation afforded the title compound in
73% yield. The spectra of this material were identical to those
reported for cyclization using 1 as the precatalyst.
1-[(P h en ylsilyl)m eth yl]-cis-bicyclo[4.3.0]n on a n e (13)
was prepared from 12 according to the general experimental
procedure for cyclization/silylation using [CpTMS2LuMe]2 as the
precatalyst. The reaction was found to be complete by GC
analysis after 1 h at room temperature. Workup and purifica-
tion by flash chromatography followed by Kugelrohr distilla-
tion afforded the title compound in 95% yield. The spectra of
this material were identical to those reported for cyclization
using 1 as the precatalyst.
cis-Bicyclo[4.3.0]n on a n e-1-m eth a n ol (14). Silane 13
was oxidized to the title compound using the general oxidation
procedure given above. The alcohol obtained was purified by
flash chromatography: Rf 0.36 (20% EtOAc/hexanes); 1H NMR
(400 MHz, CDCl3) δ 3.53 (d, J ) 10.7 Hz, 1H), 3.31 (d, J )
10.7 Hz, 1H), 1.75-1.22 (m, 16H); 13C NMR (100 MHz, CDCl3)
δ 68.8, 45.8, 39.8, 33.1, 29.2, 28.6, 26.8, 22.6, 21.9, 20.7; IR
(neat) 3333, 2925, 2858 cm-1; HRMS calcd for C10H16 (M -
H2O) 136.1252, found 136.1257; LRMS (EI+) m/z 136 (4), 123
(81), 81 (95), 31 (100).
cis-Bicyclo[4.3.0]n on a n e-1-ca r boxylic Acid (15). Alco-
hol 14 was converted to the corresponding carboxylic acid using
a literature procedure for RuO4 oxidation:32 1H NMR (400
MHz, CDCl3) δ 12.4-11.6 (br s, 1H), 2.47-2.41 (m, 1H), 1.97-
1.80 (m, 2H), 1.76-1.56 (m, 6H), 1.52-1.30 (m, 6H); 13C NMR
(100 MHz, CDCl3) δ 184.5, 52.1, 41.0, 36.1, 29.5, 28.2, 25.8,
23.0, 21.4, 21.2; IR (neat) 3200-2700, 1694 cm-1; HRMS calcd
for C10H16O2 168.1150, found 168.1152; LRMS (EI+) m/z 168
(19), 150 (11), 123 (90), 113 (56), 81 (100).
(30) Bishop, R. J . Chem. Soc., Perkin Trans. 1 1974, 2364.
(31) Butler, G. B.; Van Heiningen, J . J . J . Macromol. Sci. Chem.
1994, A8, 1139.
(32) Carlser, P. H. J .; Katsuki, T.; Martin, V. S.; Sharpless, K. B. J .
Org. Chem. 1981, 46, 3936.

3394 J . Org. Chem., Vol. 63, No. 10, 1998
Molander et al.
cis-Bicyclo[4.3.0]n on a n e-1-ca r boxa m id e (16). Carboxy-
lic acid 15 was converted to the primary carboxamide via a
literature procedure.25 The melting point of the white solid
obtained closely matched the literature values (109-110 °C,25
114-115 °C33): mp 110-111.5 °C; 1H NMR (400 MHz, CDCl3)
δ 5.85 (br s, 1H), 5.66 (br s, 1H), 2.31-2.30 (m, 1H), 1.83-
1.15 (m, 14H); 13C NMR (100 MHz, CDCl3) δ 180.4, 52.4, 40.9,
36.5, 30.6, 28.2, 26.0, 22.9, 21.4, 21.1; IR (neat) 3434, 3354,
3198, 2926, 2870, 1644, 1613 cm-1; HRMS calcd for C10H17NO
167.1310, found 167.1302; LRMS (EI+) m/z 167 (19), 150 (6),
123 (54), 112 (52), 81 (100).
chromatography followed by Kugelrohr distillation afforded the
title compound in 70% yield. The material isolated was
contaminated with 10% uncyclized hydrosilylated material
that could not be removed chromatographically. Pure cyclized
diol could be obtained after oxidation as described below: Rf
1
0.52 (hexanes); H NMR (500 MHz, CDCl3) δ 7.57-7.53 (m,
2H), 7.38-7.32 (m, 3H), 4.33-4.26 (m, 2H), 3.39 (d, J ) 9.5
Hz, 1H), 3.32 (d, J ) 9.5 Hz, 1H), 1.68-1.61 (m, 6H), 1.48-
1.34 (m, 5H), 1.30-1.20 (m, 4H), 0.98-0.89 (m, 1H), 0.86 (s,
9H), -0.01 (s, 6H); 13C NMR (125 MHz, CDCl3) δ 135.21,
133.68, 129.35, 127.91, 68.70, 48.97, 44.54, 38.08, 34.39, 30.29,
28.23, 25.91, 22.13, 21.79, 21.59, 19.37, 18.21, 15.75, -5.54,
-5.55; IR (neat) 2927.5, 2857.1, 2134.5 cm-1; HRMS calcd for
4-Aza-4-ben zyl-1-[(ph en ylsilyl)m eth yl]-cis-bicyclo[4.3.0]-
n on a n e (29) was prepared from 28 according to the general
C
19H31OSi2 (M - t-Bu) 331.1913, found 331.1890; LRMS (EI+)
experimental procedure for cyclization/silylation using [CpTMS
-
2
m/z 331 (14), 235 (23), 181 (100), 107 (66), 105 (48). Anal.
Calcd for C23H40OSi2: C, 71.06; H, 10.37. Found: C, 71.14;
H, 10.66.
YMe]2 as the precatalyst. The reaction was found to be
complete by GC analysis after 20 h at room temperature.
Workup and purification by flash chromatography followed by
Kugelrohr distillation afforded the title compound in 77%
yield: ot 160 °C/0.01 mmHg; 1H NMR (500 MHz, CDCl3) δ
7.56-7.54 (m, 2H), 7.38-7.26 (m, 7H), 7.24-7.19 (m, 1H),
4.32-4.28 (m, 2H), 3.47 (d, J ) 13.3 Hz, 1H), 3.41 (d, J ) 13.3
Hz, 1H), 2.40-2.36 (m, 1H), 2.31-2.23 (m, 3H), 1.75-1.58 (m,
7H), 1.48-1.41 (m, 2H), 1.31-1.26 (m, 1H), 1.06-1.01 (m, 1H);
13C NMR (125 MHz, CDCl3) δ 139.16, 135.19, 133.24, 129.42,
128.82, 128.08, 127.95, 126.71, 63.22, 53.62, 50.02, 47.11,
41.18, 37.02, 32.85, 27.45, 21.04, 20.63; IR (neat) 3065.8,
3024.6, 2951.3, 2873.6, 2797.0, 2759.9, 2132.9 cm-1; LRMS
(EI+) m/z 335 (3), 334 (4), 257 (5), 244 (18), 228 (11), 153 (15),
107 (30), 91 (100). Anal. Calcd for C22H29NSi: C, 78.74; H,
8.71. Found: C, 78.95; H, 8.81.
1,6-Bis(h yd r oxym eth yl)-cis-bicyclo[4.3.0]n on a n e (36).
To obtain material free of contamination, 34 was subjected to
catalytic cyclization/silylation according to the general proce-
dure. After workup the crude material was oxidized according
to the general procedure given for the preparation of 23.
Analogous workup and purification by flash chromatography
yielded the title compounds as a white solid in 58% yield: mp
207-208 °C (lit.34 mp 203 °C); Rf 0.44 (75% EtOAc/hexanes);
1H NMR (500 MHz, CDCl3) δ 3.60-3.51 (m, 4H), 2.69 (br s,
2H), 1.70-1.62 (m, 2H), 1.60-1.55 (m, 4H), 1.53-1.48 (m, 2H),
1.47-1.43 (m, 4H), 1.35-1.31 (m, 2H); 13C NMR (125 MHz,
CDCl3) δ 67.90, 47.38, 32.35, 30.63, 22.04, 18.74; IR (neat)
3267.8 br, 2931.9 cm-1; HRMS calcd for C11H18O (M - H2O)
166.1358, found 166.1358; LRMS (EI+) m/z 166 (2), 153 (10),
135 (100), 121 (24).
2-[(P h en ylsilyl)m eth yl]sp ir o[4.4]n on a n e (18) was pre-
pared from 17 according to the general experimental procedure
for cyclization/silylation using [CpTMS2YMe]2 as the precatalyst.
The reaction was found to be complete by GC analysis after 1
h at room temperature. Workup and purification by flash
chromatography followed by Kugelrohr distillation afforded the
title compound in 88% yield. The spectra of this material were
identical to those reported for cyclization using 1 as the
precatalyst.
8-[(P h en ylsilyl)m eth yl]tr icyclo[4.3.3.0]d od eca n e (38)
was prepared from 37 according to the general experimental
procedure for cyclization/silylation using [CpTMS2YMe]2 as the
precatalyst. The reaction was found to be complete by GC
analysis after 1 h at room temperature. Workup and purifica-
tion by flash chromatography followed by Kugelrohr distilla-
tion afforded the title compound in 35% yield. A 42% yield of
uncharacterized isomers assumed to be spiro[5.5]dodecane
product 39 from the cyclization of the terminal olefins was also
isolated: 1H NMR (500 MHz, CDCl3) δ 7.56-7.54 (m, 2H),
7.39-7.32 (m, 3H), 4.26 (t, J ) 4.0 Hz, 2H), 2.23-2.16 (m, 1H),
1.68 (dd, J ) 13.0, 8.0 Hz, 2H), 1.57-1.26 (m, 16H), 1.08-
1.05 (m, 2H); 13C NMR (125 MHz, CDCl3) δ 135.19, 132.98,
129.42, 127.92, 50.86, 47.46, 39.60, 32.71, 32.29, 22.50, 20.21,
18.53; IR (neat) 3067.9, 2926.0, 2857.5, 2132.2 cm-1; HRMS
calcd for C19H28Si 284.1960, found 284.1951; LRMS (EI+) m/z
284 (2), 241 (13), 206 (100), 107 (87). Anal. Calcd for
1-[(P h en ylsilyl)m et h yl]-4-oxa -cis-b icyclo[4.3.0]n on -
a n e (31) was prepared from 30 according to the general
experimental procedure for cyclization/silylation using [CpTMS
-
2
YMe]2 as the precatalyst. The reaction was found to be
complete by GC analysis after 24 h at 90 °C. Workup and
purification by flash chromatography followed by Kugelrohr
distillation afforded the title compound in 57% yield: ot 110
°C/0.05 mmHg; Rf 0.40 (5% EtOAc/hexanes); 1H NMR (300
MHz, CDCl3) δ 7.58-7.54 (m, 2H), 7.41-7.31 (m, 3H), 4.35-
4.31 (m, 2H), 3.68-3.50 (m, 3H), 3.47-3.42 (m, 1H), 1.78-
1.61 (m, 7H), 1.59-1.33 (m, 3H), 1.12-1.04 (m, 1H); 13C NMR
(75 MHz, CDCl3) δ 135.16, 132.83, 129.56, 128.03, 66.69, 64.12,
46.58, 40.53, 37.64, 32.54, 25.99, 20.73, 20.59; IR (neat) 3067.7,
2951.6, 2873.2, 2133.0 cm-1; LRMS (EI+) m/z 246 (4), 245 (15),
169 (22), 168 (14), 140 (19), 123 (27), 107 (100), 105 (66). Anal.
Calcd for C15H22OSi: C, 73.11; H, 9.00. Found: C, 73.34; H,
8.81.
6-[(P h e n ylsilyl)m e t h yl]-cis-b icyclo[4.3.0]n on a n -3-
on e, d ith ioeth a n e a ceta l (33) was prepared from 32 accord-
ing to the general experimental procedure for cyclization/
silylation using [CpTMS2YMe]2 as the precatalyst. The reaction
was found to be complete by GC analysis after 8 h at room
temperature. Workup and purification by flash chromatog-
raphy afforded the title compound in 98% yield. The product
was contaminated with 9% uncyclized hydrosilylated product
that could not be removed chromatographically: Rf 0.30 (5%
EtOAc/hexanes); 1H NMR (500 MHz, CDCl3) δ 7.56-7.54 (m,
2H), 7.38-7.31 (m, 3H), 4.35 (t, J ) 4.4 Hz, 2H), 3.30-3.24
(m, 4H), 2.04-1.65 (m, 11H), 1.36-1.29 (m, 2H), 1.13-1.05
(m, 2H); 13C NMR (125 MHz, CDCl3) δ 135.20, 133.10, 129.44,
127.97, 68.24, 46.84, 44.81, 42.54, 38.64, 38.25, 38.08, 33.88,
33.08, 29.88, 23.58, 20.50; IR (neat) 3066.4, 2922.6, 2874.5,
2133.7 cm-1; HRMS calcd for C18H26S2Si 334.1245, found
334.1237; LRMS (EI+) m/z 334 (46), 306 (8), 273 (42), 257 (20),
240 (20), 197 (80), 107 (100). Anal. Calcd for C18H26S2Si: C,
64.61; H, 7.83. Found: C, 64.51; H, 7.98.
C
19H28Si: C, 80.21; H, 9.92. Found: C, 80.42; H, 10.32.
8-Meth yl-8-[(p h en ylsilyl)m eth yl]tr icyclo[4.3.3.0]d od ec-
a n e (41) was prepared from 40 according to the general
experimental procedure for cyclization/silylation using [CpTMS
-
2
YMe]2 as the precatalyst. The reaction was found to be
complete by GC analysis after 1 h at room temperature.
Workup and purification by flash chromatography afforded the
title compound in 75% yield. A monocyclic hydrosilylated
product whose spectal data are described below was also
isolated in 14% yield: 1H NMR (500 MHz, CDCl3) δ 7.57-
7.55 (m, 2H), 7.36-7.32 (m, 3H), 4.31 (t, J ) 4.2 Hz, 2H), 1.77-
1.52 (m, 10H), 1.46-1.28 (m, 10H), 1.25 (s, 3H); 13C NMR (125
MHz, CDCl3) δ 135.20, 133.49, 129.33, 127.92, 54.38, 52.52,
(1R*,2R*)-6-[(ter t-Bu t yld im et h ylsilyloxy)m et h yl]-1-
[(p h en ylsilyl)m eth yl]bicyclo[4.3.0]n on a n e (35) was pre-
pared from 34 according to the general experimental procedure
for cyclization/silylation using [CpTMS2YMe]2 as the precatalyst.
The reaction was found to be complete by GC analysis after
16 h at room temperature. Workup and purification by flash
(34) Altman, J .; Babad, E.; Itzchaki, J .; Ginsburg D. Tetrahedron
Supl. 8. 1966, 279.
(33) Meyer, W. L.; Wolfe, J . F. J . Org. Chem. 1964, 29, 170.

Cyclization/Silylation of Hindered Dienes
J . Org. Chem., Vol. 63, No. 10, 1998 3395
39.25, 37.92, 33.86, 32.73, 31.58, 22.04, 20.89; IR (neat) 3067.9,
2925.5, 2857.5, 2134.2 cm-1; HRMS calcd for C20H30Si 298.2117,
found 298.2099; LRMS (EI+) m/z 298 (8), 283 (16), 220 (100),
107 (81).
(lit.26 mp 50-51 °C). Anal. Calcd for C13H18O: C, 82.06; H,
9.53. Found: C, 82.29; H, 9.72. 4-Phenyl-1-cyclohexanemeth-
anol was also isolated in 26% yield. This product was
identified by NMR and HRMS.
2-Meth allyl-1-m eth ylen e-2-[3-(ph en ylsilyl)pr opyl]cyclo-
h exa n e (42): minor product isolated in the preparation of 41;
1H NMR (500 MHz, CDCl3) δ 7.65-7.51 (m, 2H), 7.37-7.31
(m, 3H), 4.79-4.73 (m, 2H), 4.55-4.54 (m, 2H), 4.27 (t, J )
3.8 Hz, 2H), 2.46 (d, J ) 13.4 Hz, 1H), 2.22-2.18 (m, 1H),
2.12-2.07 (m, 1H), 1.94 (d, J ) 13.4 Hz, 1H), 1.69 (s, 3H),
1.56-1.23 (m, 10H), 0.92-0.87 (m, 2H); 13C NMR (125 MHz,
CDCl3) δ 154.52, 143.63, 135.16, 132.76, 129.46, 127.93, 114.01,
107.94, 43.13, 42.34, 38.40, 38.10, 33.79, 28.43, 25.09, 21.84,
19.02, 10.63; IR (neat) 3069.0, 2931.6, 2854.6, 2131.6, 1635.4
cm-1; HRMS calcd for C20H30Si 298.2117, found 298.2112;
LRMS (EI+) m/z 298 (1), 283 (6), 243 (8), 149 (25), 107 (100),
105 (54).
(1R*,2R*)-1-ter t-Bu tyldiph en ylsiloxy-2-[(m eth ylph en yl-
silyl)m eth yl]cycloh exa n e (53) was prepared from 52 ac-
cording to the general experimental procedure for cyclization/
silylation except using methylphenylsilane as the trapping
reagent. The reaction was found to be complete by GC analysis
after 2 d at room temperature. Workup and purification by
flash chromatography afforded the title compound in 71% yield
as a mixture of diastereomers due to the stereocenter at silicon.
The purity and identity of the major product were determined
by oxidizing the product to the diol as described below: Rf 0.35
(10% C6H6/hexanes); 1H NMR (500 MHz, CDCl3) δ 7.68-7.63
(m, 4H), 7.50-7.29 (m, 11H), 4.34-4.33 (m, 1H), 3.31-3.27
(m, 1H), 1.85-1.82 (m, 1H), 1.69-1.41 (m, 5H), 1.29-1.12 (m,
3H), 1.09-1.02 (m, 9H), 0.91-0.84 (m, 1H), 0.46-0.39 (m, 1H),
7-Met h yl-7-[(p h en ylsilyl)m et h yl]t r icyclo[3.3.3.0]u n -
d eca n e (44) was prepared from 43 according to the general
0.28-0.25 (m, 3H); IR (neat) 3069.1, 2929.7, 2114.1 cm-1
;
experimental procedure for cyclization/silylation using [CpTMS
-
HRMS calcd for C26H31OSi2 (M - t-Bu) 415.1913, found
415.1948; LRMS (EI+) m/z 415 (22), 375 (56), 319 (100). Anal.
Calcd for C30H40OSi2: C, 76.21; H, 8.53. Found: C, 76.32; H,
8.81.
tr a n s-2-(Hyd r oxym eth yl)cycloh exa n ol (54). To obtain
material free of additional stereocenters, diene 52 was cyclized
according to the general cyclization/silylation protocol. The
crude silane obtained was subjected to the oxidation procedure
and purified by flash chromatography to give a colorless oil in
51% yield for the two steps. The material obtained was
spectroscopically consistent with literature data for the trans
compound.27
1-Meth ylen e-2-[4-(p h en ylsilyl)bu tyl]cycloh exa n e (56)
was prepared from 55 according to the general experimental
procedure for cyclization/silylation using [CpTMS2YMe]2 as the
precatalyst. The reaction was found to be complete by GC
analysis after 1 h at room temperature. Workup and purifica-
tion by flash chromatography followed by Kugelrohr distilla-
tion afforded the title compound in 72% yield: ot 110 °C/0.1
mmHg; 1H NMR (500 MHz, CDCl3) δ 7.56-7.54 (m, 2H), 7.39-
7.32 (m, 3H), 4.61 (d, J ) 0.9 Hz, 1H), 4.52 (s, 1H), 4.26 (t, J
) 3.7 Hz, 2H), 2.21-2.16 (m, 1H), 2.00-1.94 (m, 2H), 1.74-
1.68 (m, 1H), 1.66-1.50 (m, 3H), 1.49-1.16 (m, 8H), 0.95-
0.91 (m, 2H); 13C NMR (125 MHz, CDCl3) δ 153.16, 135.19,
132.75, 129.46, 127.94, 105.33, 42.99, 34.76, 33.85, 31.70,
30.68, 28.86, 25.29, 24.24, 10.04; IR (neat) 3068.0, 2925.5,
2853.2, 2131.5, 1644.1 cm-1; HRMS calcd for C17H26Si 258.1804,
found 258.1813; LRMS (EI+) m/z 258 (6), 180 (30), 161 (46),
107 (100), 105 (47), 96 (96).
2
YMe]2 as the precatalyst. The reaction was found to be
complete by GC analysis after 3 h at room temperature.
Workup and purification by flash chromatography afforded the
title compound in 69% yield: Rf 0.61 (hexanes); 1H NMR (500
MHz, CDCl3) δ 7.56-7.53 (m, 2H), 7.37-7.31 (m, 3H), 4.30 (t,
J ) 4.2 Hz, 2H), 1.71-1.40 (m, 14H), 1.29-1.24 (m, 2H), 1.18
(t, J ) 4.2 Hz, 2H), 1.14 (s, 3H); 13C NMR (125 MHz, CDCl3)
δ 135.21, 133.43, 129.35, 127.92, 62.20, 55.81, 43.35, 42.61,
41.98, 29.86, 27.48, 25.24, 24.91; IR (neat) 3068.0, 2936.1,
2865.3, 2134.3 cm-1; HRMS calcd for C19H28Si 284.1960, found
284.1937; LRMS (EI+) m/z 284 (10), 269 (13), 206 (100), 191
(34), 122 (98), 107 (97), 105 (46).
1-[(P h en ylsilyl)m eth yl]cyclop en ta n e (46) was prepared
from 45 according to the general experimental procedure for
cyclization/silylation using [CpTMS2YMe]2 as the precatalyst.
The reaction was found to be complete by GC analysis after 4
h at room temperature. Workup and purification by Kugelrohr
distillation afforded the title compound in 98% yield. The
material obtained was spectroscopically identical to that
reported in the literature.6b
[(Meth ylp h en ylsilyl)m eth yl]cycloh exa n e (48) was pre-
pared from 47 according to the general experimental procedure
for cyclization/silylation except using methylphenylsilane as
the trapping reagent. The reaction was found to be complete
by GC analysis after 12 h at room temperature. Workup and
purification by Kugelrohr distillation afforded the title com-
pound in 86% yield. The material obtained was spectroscopi-
cally identical to that reported in the literature.6b
(1R*,2R*)-1-[(Met h ylp h en ylsilyl)m et h yl]-2-p h en ylcy-
cloh exa n e (50) was prepared from 49 according to the general
experimental procedure for cyclization/silylation except using
methylphenylsilane as the trapping reagent. The reaction was
found to be complete by GC analysis after 12 h at room
temperature. Workup and purification by flash chromatog-
raphy followed by Kugelrohr distillation afforded the title
compound in 56% yield as a mixture of diastereomers due to
the stereocenter at silicon. The purity and identity of the
major product were determined by oxidation to the alcohol as
2-Isop r op yl-6-(p h en ylsilyl)-1-h exen e (58) was prepared
from 57 according to the general experimental procedure for
cyclization/silylation except using [CpTMS2LuMe]2 as the pre-
catalyst. The reaction was found to be complete by GC
analysis after 1 h at room temperature. Workup and purifica-
tion by flash chromatography followed by Kugelrohr distilla-
tion afforded the title compound in 84% yield: ot 65 °C/0.05
mmHg; 1H NMR (400 MHz, CDCl3) δ 7.57-7.55 (m, 2H), 7.40-
7.32 (m, 3H), 4.71 (s, 1H), 4.64 (s, 1H), 4.29-4.27 (m, 2H), 2.20
(heptet, J ) 6.7 Hz, 1H), 2.02-1.98 (m, 2H), 1.51-1.43 (m,
4H), 1.00 (d, J ) 6.7 Hz, 6H), 0.98-0.92 (m, 2H); 13C NMR
(100 MHz, CDCl3) δ 155.98, 135.20, 132.69, 129.49, 127.96,
106.16, 34.02, 33.69, 31.34, 24.99, 21.86, 9.98; IR (neat) 3069.0,
3052.0, 2960.7, 2926.8, 2132.4, 1641.2 cm-1; HRMS calcd for
1
described below: Rf 0.35 (7.5% C6H6/hexanes); H NMR (500
MHz, CDCl3) δ 7.55-7.21 (m, 7H), 7.17-7.14 (m, 1H), 7.10-
7.04 (m, 2H), 4.30-4.28 (m, 1H), 2.20-2.14 (m, 1H), 2.01-
1.99 (m, 1H), 1.80-1.60 (m, 4H), 1.52-1.23 (m, 3H), 1.12-
0.98 (m, 1H), 0.89-0.72 (m, 1H), 0.54-0.32 (m, 1H), 0.21-
0.17 (m, 3H); 13C NMR (125 MHz, CDCl3) δ 146.62, 136.96,
134.31, 134.23, 129.00, 128.27, 127.70, 125.80, 53.73, 39.22,
36.12, 35.20, 26.89, 26.84, 19.08, -5.18; IR (neat) 3066.6,
3024.7, 2920.8, 2851.6, 2113.2, 1601.5 cm-1; HRMS calcd for
C
15H23Si (M - H) 231.1569, found 231.1547; LRMS (EI+) m/z
231 (1), 217 (3), 189 (45), 161 (47), 148 (36), 133 (20), 120 (63),
107 (100), 105 (68).
1-(2-Met h ylp r op yl)-1-[(p h en ylsilyl)m et h yl]cyclop en -
ta n e (60) was prepared from 59 according to the general
C
20H26Si 294.1804, found 294.1786; LRMS (EI+) m/z 294 (3),
experimental procedure for cyclization/silylation using [CpTMS
-
2
279 (10), 216 (38), 121 (100).
YMe]2 as the precatalyst. The reaction was found to be
complete by GC analysis after 1 h at room temperature.
Workup and purification by flash chromatography followed by
Kugelrohr distillation afforded the title compound in 52% yield.
A 36% yield of uncyclized hydrosilylated product was also
isolated as described below: ot 80 °C/0.01 mmHg; Rf 0.55
tr a n s-2-P h en ylcycloh exa n em eth a n ol (51). Substrate
49 was cyclized according to the general procedure for cycliza-
tion/silylation given above. The crude material isolated was
subjected to the general oxidation conditions to give the title
compound in 53% over two steps. The NMR spectra and
melting point closely match literature values: mp 48-49 °C
1
(hexanes); H NMR (500 MHz, CDCl3) δ 7.75-7.55 (m, 2H),

3396 J . Org. Chem., Vol. 63, No. 10, 1998
Molander et al.
7.38-7.32 (m, 3H), 4.31 (t, J ) 4.2 Hz, 2H), 1.71 (nonlet, J )
6.5 Hz, 1H), 1.64-1.57 (m, 4H), 1.52-1.42 (m, 4H), 1.35 (d, J
) 6.0 Hz, 2H), 1.14 (t, J ) 4.2 Hz, 2H), 0.90 (d, J ) 6.5 Hz,
6H); 13C NMR (125 MHz, CDCl3) δ 135.21, 133.47, 129.36,
127.93, 49.79, 44.86, 40.90, 25.31, 24.82, 23.91, 21.00; IR (neat)
3068.0, 2952.3, 2869.8, 2135.4 cm-1; HRMS calcd for C16H25Si
(M - H) 245.1726, found 245.1726; LRMS (EI+) m/z 246 (1),
189 (76), 168 (10), 161 (56), 147 (19), 107 (100), 105 (48).
7-Meth yl-5-m eth ylen e-1-(p h en ylsilyl)octa n e (61): mi-
nor product isolated from the preparation of 60; ot 70 °C/0.01
mmHg; Rf 0.38 (hexanes); 1H NMR (500 MHz, CDCl3) δ 7.57-
7.55 (m, 2H), 7.37-7.33 (m, 3H), 4.70-4.65 (m, 2H), 4.28 (t, J
) 3.7 Hz, 2H), 1.97-1.94 (m, 2H), 1.85 (d, J ) 7.2 Hz, 2H),
1.73 (nonlet, J ) 6.7 Hz, 1H), 1.51-1.42 (m, 4H), 0.98-1.93
(m, 2H), 0.85 (d, J ) 6.6 Hz, 6H); 13C NMR (125 MHz, CDCl3)
δ 148.67, 135.19, 132.69, 129.49, 127.95, 110.01, 45.91, 35.31,
30.88, 25.97, 24.89, 22.50, 9.95; IR (neat) 3068.6, 2952.8,
2925.4, 2867.2, 2132.4, 1642.0 cm-1; HRMS calcd for C16H25Si
(M - H) 245.1726, found 245.1699; LRMS (EI+) m/z 246 (1),
203 (15), 161 (40), 107 (100), 105 (40), 81 (17), 67 (13), 53 (20),
43 (73), 41 (53).
7.33 (m, 3H), 5.65-5.62 (m, 1H), 5.54-5.52 (m, 1H), 4.29-
4.27 (m, 2H), 2.05-2.02 (m, 1H), 1.97-1.93 (m, 2H), 1.78-
1.67 (m, 2H), 1.54-1.29 (m, 5H), 1.20-1.14 (m, 1H), 0.95-
0.90 (m, 2H); 13C NMR (125 MHz, CDCl3) δ 135.19, 132.70,
132.05, 129.47, 127.94, 126.78, 39.58, 34.86, 28.98, 25.38,
22.46, 21.48, 10.20; IR (neat) 3068.0, 3016.1, 2922.7, 2856.2,
2131.6, 1648.0 cm-1; HRMS calcd for C15H22Si 230.1491, found
230.1482; LRMS (EI+) m/z 230 (2), 187 (8), 173 (14), 152 (81),
107 (100), 105 (67). Anal. Calcd for C15H22Si: C, 78.19; H,
9.62. Found: C, 78.53; H, 9.57.
1-ter t-Bu tyldim eth ylsiloxy-2-[3-(m eth ylph en ylsilyl)pr o-
p yl]-1-vin ylcycloh exa n e (67). Substrate 66 was cyclized
according to the general procedure for NMR silylation given
above. The reaction was found to be complete after 4 h at room
temperature. Analogous workup and purification yielded 88%
of the title compound. The NMR spectra closely match
literature data.14
Ack n ow led gm en t. We thank Dr. Bruce Noll for the
X-ray structure determination of complex 2. We also
thank Markus Keitsch for providing a sample of
[CpTMS2LuMe]2 for the initial reactions using that
complex. We gratefully acknowledge the National
Institutes of Health (GM48580), the Fonds der Chemis-
chen Industrie, the Deutsche Forschungsgemeinschaft,
the Graduiertenkolleg “Synthesizche, mechanistische
und reaktionstechnische Aspekte von Metallkatalysa-
toren”, and NATO for their generous support of this
research. This material is based upon work supported
under a National Science Foundation Graduate Fellow-
ship to E.D.D.
1-(3-Me t h ylb u t yl)-1-[(p h e n ylsilyl)m e t h yl]cyclop e n -
ta n e (63) was prepared from 62 according to the general
experimental procedure for cyclization/silylation using [CpTMS
-
2
YMe]2 as the precatalyst. The reaction was found to be
complete by GC analysis after 1 h at room temperature.
Workup and purification by flash chromatography followed by
Kugelrohr distillation afforded the title compound in 84%
1
yield: ot 80 °C/0.01 mmHg; Rf 0.56 (hexanes); H NMR (500
MHz, CDCl3) δ 7.57-7.54 (m, 2H), 7.36-7.31 (m, 3H), 4.30 (t,
J ) 4.3 Hz, 2H), 1.63-1.56 (m, 4H), 1.45-1.42 (m, 5H), 1.40-
1.32 (m, 2H), 1.15-1.10 (m, 4H), 0.84 (d, J ) 6.6 Hz, 6H); 13
C
NMR (125 MHz, CDCl3) δ 135.21, 133.50, 129.35, 127.91,
44.22, 40.15, 38.74, 34.17, 28.75, 24.32, 22.71, 21.46; IR (neat)
3068.0, 3051.4, 2951.8, 2868.4, 2134.8 cm-1; LRMS (EI+) m/z
260 (1), 189 (74), 161 (47), 107 (100). Anal. Calcd for
Su p p or tin g In for m a tion Ava ila ble: Experimental de-
tails and characterization for substrates 5, 10, 17, 19, 21, 24,
28, 30, 32, 34, 37, 40, 43, 49, 52, 55, 57, 59, and 62 and their
precursors, NMR spectra for compounds without reported
elemental analyses, and details of the X-ray stucture deter-
mination of 2 (151 pages). This material is contained in
libraries on microfiche, immediately follows this article in the
microfilm version of the journal, and can be ordered from the
ACS; see any current masthead page for ordering information.
C
17H28Si: C, 78.38; H, 10.83. Found: C, 78.46; H, 11.04.
3-[3-(P h en ylsilyl)p r op yl]cycloh exen e (65) was prepared
from 64 according to the general experimental procedure for
cyclization/silylation except using [CpTMS2LuMe]2 as the pre-
catalyst. The reaction was found to be complete by GC
analysis after 1 h at room temperature. Workup and purifica-
tion by flash chromatography followed by Kugelrohr distilla-
tion afforded the title compound in 93% yield: ot 70 °C/0.05
mmHg; 1H NMR (500 MHz, CDCl3) δ 7.58-7.55 (m, 2H), 7.40-
J O972359K