On the mechanism of the silicon-tethered reductive Pauson-Khand reaction

Article abstract of DOI:10.1016/S0040-4020(02)00337-X

The reductive Pauson-Khand reaction (PKR) of tethered vinyl silanes likely proceeds as usual to the bicyclopentenones 2, but rapid loss of the allylic silane initiates a fragmentation process culminating in propargylic carbon reduction. Damp nitrile solvents are crucial for efficient reaction, and under dry conditions additional products are obtained including dimerized cyclopentadienones and 5-(1-amino-alkylidine) cyclopentenes. Solvent incorporated enones likely arise from enolate attack on a cobalt coordinated nitrile. A unified reaction mechanism is proposed. The first example of a PKR with an allyloxy ethynylsilane is also reported.

Full text of DOI:10.1016/S0040-4020(02)00337-X

TETRAHEDRON
Pergamon
Tetrahedron 58 *2002) 3813±3822
On the mechanism of the silicon-tethered
reductive Pauson±Khand reaction
John F. Reichwein, Scott T. Iacono and Brian L. Pagenkopf p
Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712, USA
Received 26 December 2001; accepted 20 February 2002
AbstractÐThe reductive Pauson±Khand reaction *PKR) of tethered vinyl silanes likely proceeds as usual to the bicyclopentenones 2, b ut
rapid loss of the allylic silane initiates a fragmentation process culminating in propargylic carbon reduction. Damp nitrile solvents are crucial for
ef®cient reaction, and under dry conditions additional products are obtained including dimerized cyclopentadienones and 5-*1-amino-alkyl-
idine) cyclopentenes. Solvent incorporated enones likely arise from enolate attack on a cobalt coordinated nitrile. A uni®ed reaction mechanism
is proposed. The ®rst example of a PKR with an allyloxy ethynylsilane is also reported. q 2002 Elsevier Science Ltd. All rights reserved.
The Pauson±Khand reaction *PKR) is regarded as an impor-
tant reaction for cyclopentenone construction and has been
extensively reviewed.1 Recently, we reported the ®rst PKR
of 4-oxa-3-sila-hept-1-en-6-ynes *1) that provided cyclo-
pentenones formally derived from an intermolecular reac-
tion between an alkyne and ethylene.2 The method offered
distinct advantages over reactions with ethylene in that high
pressures or special equipment were not required, and the
traceless silicon tether3 circumvents the regiochemical
ambiguity observed in the carbonyl insertion when ethylene
is used *e.g. 3 vs 4).4 As summarized in Table 1, the method
succeeded with a variety of substituents at the alkyne
terminus and at the propargylic position. While Lewis
acid mediated cleavage of the silicon±carbon bond may
be expected with enones of type 2, reduction of the
carbon±oxygen bond implicates a more complicated
mechanism. In this paper, we disclose the details of the
reductive PKR of silicon-tethered enynes and propose a
uni®ed mechanistic hypothesis consistent with deuterium
labeling studies and products observed under dry conditions
*Scheme 1).
D2O work-up *Scheme 2). Spiking the reaction of enyne 8
with 1 equiv. of enone 15 showed that signi®cant inter-
molecular proton exchange was not occurring *Scheme 3).
Additionally, no hydrogen *deuterium) exchange at the
propargylic position was observed *Scheme 4).
While detailed experimental evidence supporting a par-
ticular mechanism of the PKR has not been forthcoming,
most authors support the mechanism postulated by
Magnus,5 which was recently bolstered by theorists' calcu-
lations.6 Given the high pressures necessary to effect the
intermolecular PKR with ethylene,4 tether loss likely
occurred subsequent to the ®rst carbon±carbon bond
forming step in a Magnus-like mechanism. A mechanistic
hypothesis that accounts for the reduction is shown in
Scheme 5.
Although no bicyclic enones of type 25 were detected in
the course of our investigations, invoking their formation
and subsequent demise facilitates the formulation of a
reasonable reaction mechanism. We speculate that the
transient enones 25 terminate in a facile desilylation event
*possibly aided by a nitrile±silicon ate complex) to give
the resonance stabilized enolate 26. Both ring strain and
coordination by a cobalt carbonyl species might be expected
to facilitate loss of the silicon, in what is essentially an
activated allyl silane-like environment.7 Fissure of the
carbon±oxygen bond did not occur with the pivaldehyde-
derived enynes 17 and 19, and the silanol 20 was charac-
terized by X-ray crystallography.2 For the carbon±oxygen
cleavage to occur in this case the already severe A*1,3)
strain between the tBu group and the nPr C*2) side chain
would be exacerbated as the allylic carbon becomes trigonal
planar.8 Hindered rotation about the enone C*3) and allylic
Given the unusual reduction occurring with this PKR,
experiments designed to provide insight into the reaction
mechanism were undertaken. Simple deuterium labeling
studies indicated that the two new enone hydrogens origi-
nated from water present in the nitrile solvent at the onset of
the reaction *Table 1), and not from aqueous work-up or the
nitrile. The carbons and hydrogens at C*4) and C*5) of the
enones resonate at similar chemical shift, and their identity
was established by selective deuterium labeling at the
C*5)-carbon by deprotonation with tBuLi followed by a
1
carbon of 20 manifested in the H NMR as duplicated and
line broadened signals.
Keywords: carbonylations; enynes; reductions; silicon; tether.
Corresponding author; e-mail: pagenkopf@mail.utexas.edu
p
0040±4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020*02)00337-X

3814
J. F. Reichwein et al. / Tetrahedron 58 )2002) 3813±3822
Table 1. PKR of vinylsilane-derived enynes
Entry
Substrate
Product*s) and additives
1% H2O
1% D2Oa
1
5
6, 45%b
7a, 8%c
2
3
8, RˆMe
11, RˆPh
9, 65%
9, 69%
10, 49%
±
4
5
12, RˆnPr
14, RˆPh
13, RˆnPr, 75%
15, RˆPh, 74%
±
16, 56%
6
7
17, RˆMe
19, RˆPh
18, R0ˆH, 65%
20, R0ˆSiPh2*OH), 37%
Reaction conditions: 1 equiv. Co2*CO)8, 1 equiv. enyne, 1% H2O or D2O, re¯uxing MeCN *0.25 M), 30 min.
Mixture of stereoisomers, average %D incorporation.
a
b
Reaction time: 24 h.
Reaction time: 30 min.
c
Scheme 1.
Carbon±oxygen bond cleavage and departure of the neutral
tether remnants as polysiloxane can be envisaged to occur in
a stepwise manner giving the trimethylene methane-like
intermediate 27,9 followed by reduction to the cobalt*II)
enolate 28.10 Alternatively, donation of an electron from
cobalt into the enone pi system of 26, likely generating an
anion radical, subsequent loss of siloxane and transfer of a
second electron leads to the same intermediate 28.24 Invoca-
tion of the dianionic intermediate 28 can be circumvented
simply by enolate protonation prior to siloxane loss. In
either case, the formation of a blue/green precipitate during
the course of the reaction is consistent with cobalt serving as
the reducing agent.
At the temperature of re¯uxing acetonitrile, dienolate
tautomerization by [1,5]-H sigmatropic rearrangements
is a viable alternative to intermolecular proton transfer, a
Scheme 2.

J. F. Reichwein et al. / Tetrahedron 58 )2002) 3813±3822
3815
pathway which is disfavored in light of the crossover experi-
ment shown in Scheme 3. The [1,5]-H sigmatropic rear-
rangement can account for deuterium incorporation at
C*2) of enone 7, and C*5) of all the deuterium-labeled
enones *Table 1). In all cases examined deuterium incor-
poration was less complete at the allylic carbon, which
suggests that an intramolecular proton transfer to make a
Cp anion may be favored. The reaction with the terminal
alkyne 5 was sluggish, and extended reaction times *24 h)
were required compared to the other enynes *30 min). After
a 30 min reaction time the percent deuterium incorporation
in enone 7a was consistent with the other examples,
although the yield was low *12%, 84% based on recovered
starting material). However, after the extended reaction time
necessary for complete consumption of starting material
*24 h) extensive deuterium incorporation occurred *Scheme
6), which suggests that subsequent to the initial protonolysis
the cobalt*II) facilitates further enolization. The enol
tautomers may also be subject to [1,5]-H sigmatropic
rearrangement.
Scheme 3.
At the onset of these investigations, several established
procedures for effecting the PKR were explored, including
catalytic,11±13 promoted14 and other transition metal
mediated variants,15 but enones were only observed from
the reaction with stoichiometric Co2*CO)8 in re¯uxing
acetonitrile or similar solvents.16 Nitriles are excellent
Scheme 4.
Scheme 5. Nitrile solvent with 1% D2O.
Scheme 6.

3816
J. F. Reichwein et al. / Tetrahedron 58 )2002) 3813±3822
Scheme 7.
Figure 2. ORTEP representation of 32.
Figure 1. ORTEP representation of 31b.
Alder products were generated from several enynes, no
others provided suf®cient material for adequate characteri-
zation.
ligands for many transition metals, and are known to
displace carbon monoxide in metal carbonyl clusters.17
Electronic modi®cation of cobalt by replacing CO for a
nitrile likely facilitates ole®n insertion into the alkyne±
cobalt complex. However, the use of dry acetonitrile in
these experiments had a markedly deleterious effect on
reaction ef®ciency. In addition to lowering the yields
reported in Table 1 by 30±65%, interesting new products
were obtained under anhydrous conditions. For example, in
dry acetonitrile or propionitrile the benzaldehyde-derived
enynes 8 and 11 provided the curious solvent incorporated
enones 31a, b *Scheme 7). Solvent inclusion occurred with
either dimethyl or diphenyl substitution at silicon, but at
the current stage of development navigating the reaction
exclusively through the solvent alkylation pathway remains
elusive. The structure of 31b *mp 90±918C, Et2O) was
unambiguously established by X-ray crystallography *Fig. 1).18
Further elaboration of the mechanistic pathway invoked
above can help rationalize the products generated under
anhydrous conditions *Scheme 9). Nitriles are excellent
ligands for a variety of transition metals, and cobalt
complexes are particularly effective at activating nitriles
to nucleophilic attack.20 In this regard, nitriles are generally
insuf®ciently electrophilic to react with ketone enolates,
but enhanced nitrile electrophilicity resulting from cobalt
coordination might be expected to make an enolate alkyl-
ation pathway accessible.21 With nitrile coordination to
cobalt, an intramolecular alkylation proceeding through a
six-membered transition state becomes feasible *35).
The one enyne that provided appreciable amounts of the
nitrile alkylation product reassuringly showed the highest
deuterium incorporation at C*5) in labeling experiments
*Table 1, entry 2). While additional information is necessary
to de®ne parameters for achieving ef®cient or generalized
nitrile alkylation, the extensive conjugation afforded by the
propargylic phenyl group is a plausible alkylation asset.
The reaction of enyne 14, which has no propargylic substi-
tution, provided the expected enone 15 *21%) and the new
tricyclic enone 32 *27%, Scheme 8), the structure of 32 was
con®rmed by X-ray analysis *Fig. 2).18 Enone 32 appears
to have originated from an intermolecular Diels±Alder
reaction of dieneone 33.19 While minor amounts of Diels±
Formation of the Diels±Alder adduct 32 required cyclo-
pentenone oxidation to the dienone. A [1,3]-hydride shift
Scheme 8.

J. F. Reichwein et al. / Tetrahedron 58 )2002) 3813±3822
3817
Scheme 9. Dry nitrile solvent.
to the exocyclic cation in the zwiterionic intermediate 27b
can account for the regional redox adjustments without
involving cobalt. Interestingly, the only enyne which gener-
ated appreciable amounts of Diels±Alder product would
involve formation of a comparatively unstable primary
carbocation *27, RˆH). Alternatively, a proton transfer
from 28a to form an h5-CpCo complex such as 34 leads
to the requisite dienone oxidation state. The latter mecha-
nistic route helps explain the potent peroxidase activity
displayed only by crude reaction mixtures of enyne 14.
In conclusion, the reductive PKR of tethered vinyl silanes
likely proceeds as usual to the bicyclopentenones 2, b ut
rapid loss of the allylic silane initiates a fragmentation
process culminating in reduction of the propargylic carbon.
In the absence of protic solvent, the reactive intermediates
can attack the nitrile solvent to afford 5-*1-amino-alkyl-
idines) 31, or undergo Diels±Alder dimerization. Addition-
ally, the conversion of enyne 36 to 37 constitutes the ®rst
reported `normal' PKR with a silicon-tethered enyne.
Limited spectroscopic information suggests that solvent
inclusion and Diels±Alder products formed in trace
amounts in nearly all the reactions reported in this study.
The compounds identi®ed herein were limited to those
that were readily visualized by TLC and isolated by ¯ash
chromatography.
1. Experimental
1.1. General
PKRs were run under an atmosphere of nitrogen. Flasks
were oven or ¯amed-dried and allowed to cool in a desic-
cator prior to use. Solvents and reagents were puri®ed by
standard methods.22 Nitrile solvents were distilled from
CaH2 and purged with CO or N2 before use. Thin layer
chromatography *TLC) was performed on EM 250
Kieselgel 60 F254 silica gel plates. The plates were
visualized by staining with I2 on silica, CAM,23 ninhydrin,
or potassium permanganate.
While this Paper was concerned with the PKR of tethered
vinyl silanes, there are in principle three distinct structural
classes of silicon tethered 1,6- and 1,7-enynes based on the
location of the silicon atom: the silicon can be bound
directly to the alkyne, the ole®n or it can be positioned
somewhere in between. Enyne 36, where the silicon atom
is attached directly to the alkyne, was prepared to determine
if silacycles like 37 would be stable in the absence of a low
energy decomposition pathway *Scheme 10). The standard
PKR conditions gave the stable bicyclopentenone 37 in 45%
unoptimized yield *based on recovered starting material).
1
The H and 13C NMR data was obtained on a General
Electric QE-300 spectrometer, a Varian Unity Plus 300
spectrometer, or a Varian INOVA 500. For 1H NMR,
chemical shifts are reported in parts per million *ppm)
down®eld from tetramethylsilane and are, in all cases,
referenced to the residual proton resonance peaks: d 7.24
for CHCl3, d 7.15 for benzene-d6, 2.49 for DMSO-d6. The
13C NMR chemical shifts were reported in ppm relative to
the center peak of the solvent multiplet: d 77.0 *t) for
CDCl3, 128.0 *t) for benzene-d6. 13C NMR spectra were
1
routinely run with broadband H decoupling. HRMS *CI)
was made with a VG analytical ZAB2-E instrument. The
Scheme 10.

3818
J. F. Reichwein et al. / Tetrahedron 58 )2002) 3813±3822
percent deuterium incorporation was determined by 1H
NMR integration.
general procedure as described above for the preparation
of 1 to afford 11 as a colorless oil *2.20 g, 70%). Rf 0.60
*20% EtOAc/hexanes); IR *thin ®lm) n 3059 *m), 2962 *m),
1
1.1.1. 3,3-Dimethyl-5-phenylethyl-4-oxa-3-sila-1-decen-
6-yne .1). To a 08C, stirred solution of 1-phenyl-4-octyn-
3-ol *6.48 g, 32.0 mmol) and triethylamine *8.90 mL,
64.0 mmol) in CH2Cl2 *100 mL) was added chlorodimethyl-
vinylsilane *4.14 mL, 30.0 mmol), and the solution was
allowed to warm to rt. After 1 h, the reaction mixture was
poured into ice cold half-saturated aqueous NH4Cl
*100 mL). The organic layer was separated, and the aqueous
layer was extracted with CH2Cl2 *2£25 mL). The combined
organic layers were washed with water *50 mL), brine
*50 mL) and dried *MgSO4). After ®ltration through a
small pad of celite *2 cm thick pad on a 2 cm diameter
frit) the solvent was removed under reduced pressure.
Puri®cation of the residue by ¯ash chromatography on silica
gel using 3% EtOAc/hexanes for elution afforded the title
compound 8 as a colorless oil *8.1 g, 94%). Rf 0.34 *20%
EtOAc/hexanes); IR *thin ®lm) n 3027 *m), 2961 *s), 2231
2227 *w), 1890 *w), 1698 *m), 1117 *s) cm21; H NMR
*300 MHz, CDCl3) d 7.65±7.25 *m, 15H), 6.65 *dd, Jˆ
14.9, 20.1 Hz, 1H), 6.50 *dd, Jˆ4.3, 14.8 Hz, 1H), 5.95
*dd, Jˆ4.2, 20.0 Hz, 1H), 5.60 *t, Jˆ2.0 Hz, 1H), 1.50 *dt,
Jˆ2.0, 7.3 Hz, 2H), 1.55±1.40 *m, 2H), 0.95 *t, Jˆ7.5 Hz,
3H); 13C NMR *75 MHz, CDCl3) d 142.3, 137.4, 135.7,
134.7, 134.6, 134.3, 130.3, 128.6, 128.1, 126.9, 87.9, 81.3,
66.4, 22.3, 21.2, 13.9; HRMS m/z calcd for C26H27OSi
[M1H]1 383.1831, found 383.1819.
1.1.5. 3,3-Dimethyl-4-oxa-3-sila-1-decen-6-yne .12). The
title compound was prepared according to the general pro-
cedure as described above for the preparation of 1 to afford
12 as a colorless oil *4.90 g, 89%). Rf 0.75 *20% EtOAc/
hexanes); IR *thin ®lm) n 2963 *s), 2871 *s), 2230 *w), 1629
*m), 1255 *s), 1146 *s), 1077 *s) cm21; 1H NMR *300 MHz,
CDCl3) d 6.15 *dd, Jˆ14.9, 19.7 Hz, 1H), 6.01 *dd, Jˆ4.6,
14.9 Hz, 1H), 5.79 *dd, Jˆ4.6, 19.7 Hz, 1H), 4.25 *t, Jˆ
2.0 Hz, 2H), 2.15 *dt, Jˆ2.0, 7.2 Hz, 2H), 1.54±1.47 *m,
2H), 0.95 *t, Jˆ7.2 Hz, 3H), 0.22 *s, 3H), 0.21 *s, 3H); 13C
NMR *75 MHz, CDCl3) d 137.2, 133.8, 86.0, 78.6, 51.8,
22.2, 21.0, 13.8, 21.8; HRMS m/z calcd for C10H19OSi
[M1H]1 183.1205, found 183.1206.
*w), 1594 *m), 1455 *m), 1340 *m), 1251 *s), 1088 *s) cm21
;
1H NMR *300 MHz, CDCl3) d 7.34±7.18 *m, 5H), 6.21 *dd,
Jˆ14.9, 19.0 Hz, 1H), 6.04 *dd, Jˆ4.1, 14.9 Hz, 1H), 5.83
*dd, Jˆ4.1, 21.3 Hz, 1H), 4.40 *m, 1H), 2.78 *t, Jˆ6.9 Hz,
2H), 2.22 *dt, Jˆ2.1, 7.2 Hz, 2H), 2.01±1.97 *m, 2H), 1.63±
1.51 *m, 2H), 1.02 *t, Jˆ7.4 Hz, 3H), 0.28 *s, 3H), 0.27 *s,
3H); 13C NMR *75 MHz, CDCl3) d 142.1, 138.0, 133.3,
128.7, 128.6, 126.0, 85.5, 81.6, 62.8, 40.6, 31.8, 22.3,
21.0, 13.8, 21.1, 21.3; HRMS m/z calcd for C18H27OSi
[M1H]1 287.1831, found 287.1833.
1.1.6.
3,3-Dimethyl-4-oxa-7-phenyl-3-sila-1-hepten-6-
yne .14). The title compound was prepared according to
the general procedure as described above for the preparation
of 1 to afford 14 as a colorless oil *4.51 g, 88%). Rf 0.95
*10% EtOAc/hexanes); IR *thin ®lm) n 3052 *s), 2957 *s),
1.1.2. 3,3-Dimethyl-5-phenylethyl-4-oxa-3-sila-1-hepten-
6-yne .5). The title compound was prepared according to the
general procedure as described above for the preparation of
1 to afford 5 as a colorless oil *4.20 g, 86%). Rf 0.62 *20%
EtOAc/hexanes); IR *thin ®lm) n 3305 *s), 2955 *s), 2113
1
2242 *w), 1256 *s), 1080 *s) cm21; H NMR *300 MHz,
CDCl3) d 7.44±7.28 *m, 5H), 6.20 *dd, Jˆ14.9, 19.7 Hz,
1H), 6.06 *dd, Jˆ4.4, 14.9 Hz, 1H), 5.85 *dd, Jˆ4.4, 19.7
Hz, 1H), 4.51 *s, 2H), 0.28 *s, 6H); 13C NMR *75 MHz,
CDCl3) d 137.1, 134.1, 131.9, 128.6, 128.5, 123.1,
87.7, 85.4, 52.1, 21.7; HRMS m/z calcd for C13H17OSi
[M1H]1 217.1049, found 217.1051.
*w), 1943 *w), 1591 *w), 1496 *m), 1253 *s), 1093 *s) cm21
;
1H NMR *300 MHz, CDCl3) d 7.35±7.24 *m, 5H), 6.22 *dd,
Jˆ14.9, 20.0 Hz, 1H), 6.07 *dd, Jˆ4.4, 14.9 Hz, 1H), 5.86
*dd, Jˆ4.4, 20.0 Hz, 1H), 4.41 *dt, Jˆ1.8, 6.4 Hz, 1H),
2.84±2.78 *m, 2H), 2.48 *t, Jˆ2.05 Hz, 1H), 2.09±2.02
*m, 2H), 0.31 *s, 3H), 0.29 *s, 3H); 13C NMR *75 MHz,
CDCl3) d 141.7, 137.5, 133.8, 128.7, 128.6, 126.2, 85.2,
73.0, 62.3, 40.1, 31.5, 21.3, 21.4; HRMS m/z calcd for
C15H21OSi [M1H]1 245.1361, found 245.1354.
1.1.7. 3,3-Dimethyl-5-.1,1-dimethylethyl)-4-oxa-3-sila-1-
decen-6-yne .17). The title compound was prepared accord-
ing to the general procedure as described above for the
preparation of 1 to afford 17 as a colorless oil *1.87 g,
85%). Rf 0.65 *20% EtOAc/hexanes); IR *thin ®lm) n
3051 *w), 2958 *s), 2228 *w), 1250 *m), 1073 *s) cm21
;
1.1.3. 3,3-Dimethyl-4-oxa-5-phenyl-3-sila-1-decen-6-yne
.8). The title compound was prepared according to the
general procedure as described above for the preparation
of 1 to afford 8 as a colorless oil *2.10 g, 91%). Rf 0.77
*10% EtOAc/hexanes); IR *thin ®lm) n 3050 *w), 2963
*s), 2260 *w), 2230 *w), 1594 *m), 1252 *s), 1059 *s)
1H NMR *300 MHz, CDCl3) d 6.20 *dd, Jˆ14.9, 19.8 Hz,
1H), 6.02 *dd, Jˆ4.4, 14.4 Hz, 1H), 5.81 *dd, Jˆ4.1, 20.2
Hz, 1H), 3.98 *t, Jˆ2.1 Hz, 1H), 2.20 *dt, Jˆ2.1, 6.9 Hz,
2H), 1.58±1.51 *m, 2H), 1.00 *t, Jˆ7.4 Hz, 3H), 0.95 *s,
9H), 0.25 *s, 3H), 0.23 *s, 3H); 13C NMR *75 MHz, CDCl3)
d 138.3, 133.0, 85.5, 80.6, 72.0, 36.4, 25.7, 22.4, 21.0, 13.8,
21.2, 21.5; HRMS m/z calcd for C14H27OSi [M1H]1
239.1831, found 239.1814.
1
cm21; H NMR *300 MHz, CDCl3) d 7.54±7.28 *m, 5H),
6.23 *dd, Jˆ14.9, 20.0 Hz, 1H), 6.06 *dd, Jˆ4.4, 14.9 Hz,
1H), 5.85 *dd, Jˆ4.1, 20.0 Hz, 1H), 5.52 *t, Jˆ2.0 Hz, 1H),
2.25 *dt, Jˆ2.0, 7.2 Hz, 2H), 1.61±1.54 *m, 2H), 1.01 *t,
Jˆ7.4 Hz, 3H), 0.32 *s, 3H), 0.26 *s, 3H); 13C NMR *75
MHz, CDCl3) d 142.2, 137.7, 133.6, 128.5, 127.9, 126.7,
87.0, 81.1, 65.3, 22.2, 21.1, 13.8, 21.1, 21.2; HRMS m/z
calcd for C16H23OSi [M1H]1 259.1518, found 259.1510.
1.1.8. 3,3-Diphenyl-5-.1,1-dimethylethyl)-4-oxa-3-sila-1-
decen-6-yne .19). The title compound was prepared accord-
ing to the general procedure as described above for the
preparation of 1 to afford 19 as a colorless oil *4.80 g,
85%). Rf 0.65 *20% EtOAc/hexanes); IR *thin ®lm) n
3051 *w), 2958 *s), 2361 *w), 1428 *m), 1063 *s) cm21
;
1.1.4. 3,3-Diphenyl-4-oxa-5-phenyl-3-sila-1-decen-6-yne
.11). The title compound was prepared according to the
1H NMR *300 MHz, CDCl3) d 7.68±7.39 *m, 10H), 6.52
*dd, Jˆ14.9, 20.2 Hz, 1H), 6.29 *dd, Jˆ3.8, 14.9 Hz, 1H),

J. F. Reichwein et al. / Tetrahedron 58 )2002) 3813±3822
3819
5.98 *dd, Jˆ3.6, 20.2 Hz, 1H), 4.04 *t, Jˆ2.0 Hz, 1H), 2.24
*dt, Jˆ1.8, 6.9 Hz, 2H), 1.62±1.54 *m, 2H), 1.04 *t, Jˆ
7.4 Hz, 3H), 1.03 *s, 9H); 13C NMR *75 MHz, CDCl3) d
136.6, 135.7, 135.0, 134.9, 130.3, 128.1, 86.4, 80.3, 71.9,
36.1, 25.6, 22.5, 21.0, 13.8; HRMS m/z calcd for C24H31OSi
[M1H]1 363.2144, found 363.2123.
*139 mg, 65%). Rf 0.70 *40% EtOAc/hexanes); IR *thin
®lm) n 3386 *w, br), 2959 *m), 1698 *s), 1640 *s), 1494
1
*w), 1360 *w) cm21; H NMR *300 MHz, CDCl3) d 7.36±
7.17 *m, 5H), 3.77 *s, 2H), 2.39±2.28 *m, 6H), 1.54±1.46
*m, 2H), 0.96 *t, Jˆ7.4 Hz, 3H); 13C NMR *75 MHz,
CDCl3) d 210.3, 171.4, 141.2, 137.7, 129.1, 128.7, 127.0,
37.7, 34.5, 29.2, 25.6, 22.2, 14.5; HRMS m/z calcd for
C15H19O [M1H]1 215.1436, found 215.1432.
1.1.9. 2-Propyl-3-phenylpropyl-2-cylcopenten-1-one .4).
To a solution of Co2*CO)8 *342 mg, 1.00 mmol) and H2O
*36 mL, 2 mmol) in MeCN *4 mL) under an atmosphere of
N2 was added enyne 1 *287 mg, 1.00 mmol) in MeCN
*1 mL). After stirring for 1 h at rt, the reaction ¯ask was
placed into a preheated oil bath *1358C) to bring the reaction
mixture quickly to re¯ux. After 30 min the reaction ¯ask
was removed from the oil bath and allowed to cool to rt. The
volatile components were removed in vacuo, and the residue
was puri®ed by ¯ash chromatography on silica gel using
40% EtOAc/hexanes for elution to afford the title compound
4 as a pale yellow oil *149 mg, 62%). Rf 0.65 *40% EtOAc/
hexanes); IR *thin ®lm) n 3447 *br, m), 2930 *m), 1706 *s),
1.1.14. 3-Phenyl.methyl-d1)-4,5-d2-2-propyl-2-cyclopen-
ten-1-one .10). The title compound was prepared from 16
according to the general procedure described for the
preparation of 4 in the presence of D2O instead of H2O
1
*105 mg, 49%). Rf 0.70 *40% EtOAc/hexanes); H NMR
*300 MHz, CDCl3) d 7.37±7.17 *m, 5H), 3.78±3.75 *m,
1.27H), 2.41±2.39 *m, 1.73H), 2.39±2.28 *m, 3.36H),
1.53±1.46 *m, 2H), 0.96 *t, Jˆ7.4 Hz, 3H); 13C NMR
*75 MHz, CDCl3) d 210.0, 171.2, 140.9, 137.4, 128.8,
128.4, 126.7, 37.4, 37.1 *Jcdˆ19.3 Hz, CDH), 34.2, 34.0
*Jcdˆ16.5 Hz, CDH), 28.9, 25.3, 21.9, 14.2; HRMS m/z
calcd for C15H17D2O [M1H]1 216.1483, found 216.1476.
1
1614 *s) cm21; H NMR *300 MHz, CDCl3) d 7.34±7.19
*m, 5H), 2.69 *t, Jˆ7.8 Hz, 2H), 2.50±2.45 *m, 4H), 2.39±
2.36 *m, 2H), 2.13 *t, Jˆ7.5 Hz, 2H), 1.91±1.85 *m, 2H),
1.43±1.36 *m, 2H), 0.88 *t, Jˆ7.5, 3H); 13C NMR *75 MHz,
CDCl3) d 210.3 *C), 173.7 *C), 141.7 *C), 140.8 *C), 128.7
*CH), 128.6 *CH), 126.3 *CH), 36.1 *CH2), 34.5 *CH2), 31.0
*CH2), 29.4 *CH2), 29.2 *CH2), 25.4 *CH2), 22.1 *CH2), 14.4
*CH3); HRMS m/z calcd for C17H23O [M1H]1 243.1749,
found 243.1741.
1.1.15. 3-Methyl-2-propyl-2-cyclopenten-1-one .13). The
title compound 13 was prepared from 12 according to
the general procedure described for the preparation of 4
1
*103 mg, 75%). H NMR *300 MHz, CDCl3) d 2.51±2.48
*m, 2H), 2.39±2.35 *m, 2H), 2.16 *t, Jˆ7.7 Hz, 2H), 2.06 *s,
3H), 1.47±1.35 *m, 2H), 0.89 *t, Jˆ7.4 Hz, 3H); 13C NMR
*75 MHz, CDCl3) d 209.9, 170.3, 140.9, 34.7, 31.9, 25.3,
21.9, 17.6, 14.4
1.1.10. 3-Phenylpropyl-2-cyclopenten-1-one .6). The title
compound 6 was prepared from 5 according to the general
procedure described for the preparation of 4 except that
reaction time was 24 h *91 mg, 45%). Rf 0.25 *40%
EtOAc/hexanes); 1H NMR *300 MHz, CDCl3) d 7.32±
7.19 *m, 5H), 5.99 *s, 1H), 2.71 *t, Jˆ7.7 Hz, 2H), 2.60±
2.58 *m, 2H), 2.46±2.41 *m, 4H), 2.00±1.90 *m, 2H); 13C
NMR *75 MHz, CDCl3) d 210.3, 182.8, 141.6, 129.9, 128.7,
128.6, 126.4, 35.7, 35.5, 33.2, 31.8, 28.9.
1.1.16. 3-Methyl-2-phenyl-2-cyclopenten-1-one .15). The
title compound was prepared from 14 according to the
general procedure described for the preparation of 4
*187 mg, 74%). Rf 0.56 *40% EtOAc/hexanes); IR *thin
®lm) n 2922 *m), 1695 *s), 1653 *m), 1495 *m), 1132 *m)
1
cm21; H NMR *300 MHz, CDCl3) d 7.38±7.26 *m, 5H),
2.62±2.59 *m, 2H), 2.52±2.49 *m, 2H), 2.13 *s, 3H); 13C
NMR *75 MHz, CDCl3) d 208.9 *C), 172.0 *C), 140.6 *C),
132.1 *C), 129.4 *CH), 128.5 *CH), 127.9 *CH), 35.1 *CH2),
32.1 *CH2), 18.6 *CH3); HRMS m/z calcd for C12H12O
[M1H]1 173.0966, found 173.0962.
1.1.11. 3-Phenyl.propyl-1-d1)-4,5-d2-2-cyclopenten-1-
one .7a). The title compound 7a was prepared from 5
according to the general procedure described for the
preparation of 4 except that 1% of D2O was used *16 mg,
1.1.17. 3-.Methyl-d1)-2-phenyl-4,5-d2-cyclopenten-1-one
.16). The title compound was prepared from according to
the general procedure described for the preparation of
4 except that 3 equiv. of D2O was added *97 mg,
0.56 mmol, 56%). Rf 0.56 *40% EtOAc/hexanes); 1H
NMR *300 MHz, C6D6) d 7.40±7.37 *m, 2H), 7.27±7.22
*m, 2H), 7.14±7.12 *m, 1H), 2.07±2.04 *m, 1.72H), 1.81±
1.78 *m, 1.46H), 1.60±1.58 *m, 2.28H); 13C NMR *75 MHz,
CDCl3) d 207.5 *C), 171.7 *C), 140.2 *C), 131.6 *C), 128.9
*CH), 128.0 *CH), 127.3 *CH), 34.6 *CH2), 31.2
*Jcdˆ19.9 Hz, CDH), 17.9 *Jcdˆ19.3 Hz, CDH2); 13C
NMR *75 MHz, C6D6) d 205.5 *C), 169±8 *C), 140.1 *C),
132.7 *CH), 129.6 *CH), 77.9 *CH2), 77.4 *Jcdˆ18.4 Hz,
CDH), 31.3 *CH2), 31.0 *Jcdˆ20.3 Hz, CDH), 17.8 *CH3),
17.5 *Jcdˆ19.8 Hz, CD2H); 13C NMR *75 MHz, CDCl3) d
207.5 *C), 171.7 *C), 140.2 *C), 131.6 *C), 128.9 *CH),
128.2 *CH), 127.3 *CH), 34.6 *CH2), 31.6 *CH2), 31.2
*Jcdˆ19.9 Hz, CDH), 18.1 *CH3), 31.2 *Jcdˆ19.3 Hz,
CDH2); HRMS m/z calcd for C12H10D2O [M1H]1
175.1092, found 175.1089.
1
8%). Rf 0.25 *40% EtOAc/hexanes); H NMR *300 MHz,
CDCl3) d 7.32±7.19 *m, 5H), 5.99 *s, 0.78H), 2.71 *t,
Jˆ7.7 Hz, 2H), 2.60±2.58 *m, 1.29H), 2.46±2.41 *m, 3H),
2.00±1.90 *m, 2H); HRMS m/z calcd for C14H15D2O
[M1H]1 203.1405, found 203.1407.
1.1.12. 3-Phenyl.propyl-1-d1)-4,5-d2-2-cyclopenten-1-
one .7b). The title compound 7b was prepared from 5
according to the general procedure described for the
preparation of 4 except that reaction time was 24 h
1
*86 mg, 46%). Rf 0.25 *40% EtOAc/hexanes); H NMR
*300 MHz, CDCl3) d 7.32±7.19 *m, 5H), 5.99 *s, 0.46H),
2.71 *t, Jˆ7.7 Hz, 2H), 2.60±2.58 *m, 1.38H), 2.46±2.41
*m, 2.12H), 2.00±1.90 *m, 2H); HRMS m/z calcd for
C14H14D3O [M1H]1 203.145, found 204.146.
1.1.13. 3-Benzyl-2-propyl-2-cyclopenten-1-one .9). The
title compound was prepared from 8 according to the
general procedure described for the preparation of 4

3820
J. F. Reichwein et al. / Tetrahedron 58 )2002) 3813±3822
1.1.18. 3-.1-Hydroxy-2,2-dimethylpropyl)-2-propyl-2-
cyclopenten-1-one .18). The title compound was prepared
from 17 according to the general procedure described for the
preparation of 4 *136 mg, 65%). Rf 0.35 *40% EtOAc/
hexanes); IR *thin ®lm) n 3432 *s, br), 2962 *s), 2227 *w),
m/z calcd for C12H11DO [M1H]1 174.1029, found
174.1032.
1.1.22. 1,1-d2-3-Phenyl-2-propyn-1-ol. To a 2788C,
stirred solution of phenylacetylene *1.40 mL, 15.0 mmol)
in THF *20 mL) was added dropwise nBuLi *2.7 M in
hexane 5.0 mL, 13.5 mmol). After 5 min, paraformalde-
hyde-d2 *480 mg, 15.0 mmol) was added in one portion.
The solution was allowed to warm to rt. After 1 h, the solu-
tion was treated with saturated aqueous NH4Cl *20 mL).
The organic layer was separated, and the aqueous layer
was extracted with EtOAc *2£10 mL). The combined
organic layers were washed with water *20 mL), brine
*20 mL) and dried *MgSO4). Flash chromatography *silica
gel, 20% EtOAc/hexanes) gave the title compound as a pale
yellow oil *1.42 g, 10.5 mmol) in 71% yield. Rf 0.42 *20%
EtOAc/hexanes); 1H NMR *300 MHz, CDCl3) d 7.70±7.36
*m, 5H), 2.41 *s, 1H); 13C NMR *75 MHz, CDCl3) d 132.1
*C), 128.8 *CH), 128.7 *CH), 123.0 *CH), 86.6 *C), 86.0 *C),
51.4 *C, J not determined).
1
1730 *s), 1460 *s), 1367 *s), 1245 *s), 1048 *s) cm21; H
NMR *300 MHz, CDCl3) d 4.48 *s, 1H), 2.86±2.80 *m, 1H),
2.62±2.55 *m, 1H), 2.40±2.38 *m, 2H), 2.28±2.13 *m, 2H),
1.87 *s, 1H), 1.50±1.40 *m, 2H), 1.03 *s, 9H), 0.93 *t,
Jˆ7.2 Hz, 3H); 13C NMR *75 MHz, CDCl3) d 210.7,
171.9, 142.7, 76.9, 36.9, 34.4, 27.0, 26.9, 26.6, 21.6, 14.6;
HRMS m/z calcd for C13H23O2 [M1H]1 211.1698, found
211.1692.
1.1.19. 3-[1-.Hydroxy-diphenyl-silanyloxy)-2,2-dimethyl-
propyl]-2-propyl-2-cyclpenten-1-one .20). The title
compound 20 was prepared from 19 according to the
general procedure described for the preparation of 4
*143 mg, 37%). Mp 95±988C *hexanes), Rf 0.10 *20%
EtOAc/hexanes); 1H NMR *500 MHz, CDCl3) d 7.67±
7.28 *m, 10H), 4.70 *s, 1H), 3.60 *s, 1H), 2.82±2.70 *m,
1H), 2.58±2.44 *m, 1H), 2.22±2.17 *m, 1H), 2.05±1.99
*m, 1H), 1.98±1.78 *m, 2H), 1.22±1.17 *m, 2H), 0.98 *s,
9H), 0.78 *t, Jˆ7.4 Hz, 3H); 13C NMR *125 MHz, CDCl3) d
210.4, 170.9, 142.2, 134.7, 134.4, 133.4, 133.3, 130.5,
127.9, 127.8, 37.0, 34.1, 26.9, 26.6, 26.5, 20.9, 14.5;
HRMS m/z calcd for C25H33O3Si [M1H]1 408.2120,
found 408.2118.
1.1.23. 5,5-d2-3,3-Dimethyl-4-oxa-3-sila-7-phenyl-hept-
1-en-6-yne .23). The title compound was prepared from
1,1-d2-3-phenyl-2-propyn-1-ol according to the general
procedure described for the preparation of 1. Flash chroma-
tography *silica gel, 10% EtOAc/hexanes) gave 23 as a pale
yellow oil *1.43 g, 8.5 mmol) in 85% yield. Rf 0.85 *10%
EtOAc/hexanes); 1H NMR *300 MHz, CDCl3) d 7.46±7.28
*m, 5H), 6.22 *dd, Jˆ19.8, 14.9 Hz, 1H), 6.08 *dd, Jˆ14.9,
4.3 Hz, 1H), 5.87 *dd, Jˆ19.9, 4.3 Hz, 1H), 0.31 *s, 3H); 13C
NMR *75 MHz, CDCl3) d 136.3 *CH), 133.8 *C), 131.6
*CH), 128.2 *CH), 122.8 *CH2), 87.3 *C), 85.0 *C), 51.2
*Jcdˆ22.6 Hz, CD2), 22.0 *CH3).
1.1.20. 3-Benzyl-2-propyl-5-d-2-cyclopenten-1-one .21).
To a 2788C solution of enone 9 *99 mg, 0.46 mmol) in
THF *2.0 mL) was added dropwise tBuLi *1.28 M in
pentane 0.5 mL, 0.64 mmol). After 5 min, D2O *0.25 mL,
12.5 mmol) was added in one portion. The solution was
allowed to warm to rt, and after 1 h the solution was
extracted with CH2Cl2 *3£5 mL). The combined organic
layers were dried *MgSO4) and concentrated in vacuo.
Puri®cation by ¯ash chromatography *silica gel, 20%
EtOAc/hexanes) gave 21 as a pale yellow oil *49 mg,
0.23 mmol) in 49% yield. Rf 0.70 *40% EtOAc/hexanes);
1H NMR *300 MHz, CDCl3) d 7.36±7.17 *m, 5H), 3.77 *s,
2H), 2.40±2.28 *m, 5.H), 1.54±1.46 *m, 2H), 0.96 *t,
Jˆ7.4 Hz, 3H); 13C NMR *75 MHz, CDCl3) d 210.3,
171.4, 141.2, 137.7, 129.1, 128.7, 127.0, 37.7, 33.9 *Jcdˆ
20.3 Hz, CDH), 29.2, 25.6, 22.2, 14.5; HRMS m/z calcd for
C15H18DO [M1H]1 216.1499, found 216.1495.
1.1.24. 3-.1,1-d2-Methyl)-2-phenyl-2-cyclopenten-1-one
.24). The title compound was prepared from 23 according
to the general procedure described for the preparation of 4
*34 mg, 0.20 mmol) in 22% yield. Rf 0.55 *40% EtOAc/
1
hexanes); H NMR *300 MHz, CDCl3) d 7.42±7.26 *m,
5H), 2.65±2.64 *m, 2H), 2.55±2.53 *m, 2H), 2.13 *s, 1H);
13C NMR *75 MHz, CDCl3) d 207.6 *C), 171.7 *C), 140.4
*C), 131.8 *C), 129.1 *CH), 128.3 *CH), 127.6 *CH), 34.81
*CH2), 31.8 *CH2), 17.8 *Jcdˆ19.8 Hz, CHD2); HRMS m/z
calcd for C12H11DO [M1H]1 175.1092, found 175.1089.
1.1.25. .Z)-5-.1-Aminoethylidene-d3)-3-benzyl-2-propyl-
2-cyclopenten-1-one .31a). The title compound 31a was
prepared from 8 according to the general procedure
described for the preparation of 4, except that dry CD3CN
was used as solvent *19 mg, 20%). Rf 0.40 *40% EtOAc/
hexanes); IR *thin ®lm) n 3369 *m, br), 2958 *m), 1636 *s),
1.1.21. 3-Methyl-2-phenyl-5-d-2-cyclopenten-1-one .22).
To a 2788C solution of enone 15 *120 mg, 0.70 mmol) in
THF *2.0 mL) was added dropwise tBuLi *1.28 M in pen-
tane 1.0 mL, 1.28 mmol). After 5 min, D2O *0.50 mL,
25 mmol) was added in one portion. The solution was
allowed to warm to rt, and after 1 h the solution was
extracted with CH2Cl2 *3£5 mL). The combined organic
layers were dried *MgSO4) and concentrated in vacuo.
Puri®cation by ¯ash chromatography *silica gel, 20%
EtOAc/hexanes) gave 22 as a pale yellow oil *54 mg,
0.31 mmol) in 45% yield. Rf 0.56 *40% EtOAc/hexanes);
1H NMR *300 MHz, CDCl3) d 7.45±7.29 *m, 5H),
2.68±2.66 *m, 2H), 2.58±2.54 *m, 1H), 2.20 *m, 3H); 13C
NMR *75 MHz, CDCl3) d 207.6 *C), 171.8 *C), 140.2
*C), 131.7 *C), 129.0 *CH), 128.1 *CH), 127.5 *CH),
34.7 *Jcdˆ20.3 Hz, CDH), 31.7 *CH2), 18.2 *CH3); HRMS
1
1540 *s) cm21; H NMR *300 MHz, CDCl3) d 7.30±7.12
*m, 5H), 3.73 *s, 2H), 2.79 *s, 2H), 2.33 *t, Jˆ7.0 Hz, 2H),
2.62±1.51 *m, 2H), 0.94 *t, Jˆ7.2 Hz, 3H); 13C NMR
*75 MHz, CDCl3) d 195.8, 156.7, 151.7, 143.2, 139.3,
129.0, 128.8, 126.6, 104.0, 36.6, 34.2, 26.0, 22.5, 14.6;
HRMS m/z calcd for C17H19D3NO [M1H]1 259.1890,
found 259.1900
1.1.26. .Z)-5-.1-Aminopropylidene)-3-benzyl-2-propyl-
2-cyclopenten-1-one .31b). The title compound 31b was
isolated from 11 according to the general procedure
described for the preparation of 4, except that dry EtCN

J. F. Reichwein et al. / Tetrahedron 58 )2002) 3813±3822
3821
was used as solvent *85 mg, 21%). Mp 90±918C *Et2O), Rf
0.45 *40% EtOAc/hexanes); IR *thin ®lm) n 3377 *w, br),
2959 *m), 1636 *s), 1539 *s), 1453 *w), 1360 *w) cm21; 1H
NMR *300 MHz, C6D6) d 7.14±7.00 *m, 5H), 3.48 *s, 2H),
2.62 *s, 2H), 2.50 *t, Jˆ7.4 Hz, 2H), 1.76±1.69 *m, 2H),
1.50 *q, Jˆ7.7 Hz, 2H), 0.96 *t, Jˆ7.4 Hz, 3H), 0.60 *t,
Jˆ7.7 Hz, 3H); 13C NMR *75 MHz, C6D6) d 195.6 *C),
155.7 *C), 155.1 *C), 143.8 *C), 139.6 *C), 129.0 *CH),
128.8 *CH), 126.5 *CH), 102.6 *C), 36.5 *CH2), 33.6
*CH2), 26.6 *CH2), 26.3 *CH2), 22.7 *CH2), 14.5 *CH3),
11.4 *CH3); HRMS m/z calcd for C18H24NO [M1H]1
270.1858, found 270.1863.
*SiO2, EtOAc/hexane 1:9±1:3 gradient for elution) gave
recovered 36 *62 mg, 0.20 mmol, 77%) and bicyclic enone
37 *9 mg, 26.9 mmol) as a colorless oil in 10% yield. Rf 0.58
*25% EtOAc/hexanes); 1H NMR *300 MHz, CDCl3) d 7.71±
7.32 *m, 10H, ArH), 4.25 *dd, Jˆ11.4, 3.9 Hz, 1H), 3.78±
3.71 *m, 1H), 3.42 *br s, 1H), 2.56 *dd, Jˆ19.2, 6.9 Hz, 1H),
1.97±1.85 *m, 3H), 1.04±0.88 *m, 2H), 0.45 *t, Jˆ7.4 Hz,
3H); HRMS *CI) calcd for C21H22O2Si [M1H]1 335.1467,
found 335.1472.
Acknowledgements
1.1.27. Dimer 32. 1H NMR *300 MHz, CDCl3) d 7.48±7.32
*m, 8H), 7.17±7.14 *m, 2H), 6.22 *br s, 1H), 4.06 *d, Jˆ
6.7 Hz, 1H), 3.59±3.36 *m, 1H), 3.18 *br s, 1H), 2.15 *s,
6H); 13C NMR *75 MHz, CDCl3) d 204.4, 199.9, 168.8,
148.5, 141, 8, 132.9, 131.2, 129.8, 129.3, 128.9, 128.7,
128.5, 128.0, 124.5, 66.2, 50.2, 46.1, 43.4, 31.2, 19.3,
16.7; HRMS m/z calcd for C24H21O2 [M1H]1 341.1542,
found 341.1540.
We thank the Robert A. Welch Foundation for ®nancial
support of our work, Professor Nathan L. Bauld for helpful
discussions, and Vincent Lynch for determination of the
X-ray structures.
References
1. *a) Schore, N. E. Org. React. 1991, 40, 1±90. *b) Shore, N. E.
Comprehensive Organometallic Chemistry II; Hegedus, L. S.,
Ed.; Elsevier: Oxford, 1995; Vol. 12, p. 703. *c) Ingate, S. T.;
Marco-Contelles, J. Org. Prep. Proced. Int. 1998, 30, 121±
143. *d) Geis, O.; Schmalz, H.-G. Angew. Chem., Int. Ed.
1998, 37, 911±914. *e) Chung, Y. K. Coord. Chem. Rev.
1999, 188, 297±341. *f) Brummond, K. M.; Kent, J. L.
Tetrahedron 2000, 56, 3263±3283. *g) Fletcher, A. J.;
Christie, S. D. R. J. Chem. Soc., Perkin Trans. 1 2000,
1657±1668. *h) Sugihara, T.; Yamaguchi, M.; Nishizawa,
M. Chem. Eur. J. 2001, 7, 1589±1595.
1.1.28. 5,5-Diphenyl-4-oxa-5-sila-1-decen-6-yne .36). To
a cooled *08C) solution of 1-pentyne *4.9 mL, 50 mmol) in
THF *50 mL) was slowly added 0.825 M BuMgBr in Et2O
*50 mL, 41.3 mmol). The reaction mixture was stirred at rt
for 1 h followed by addition of dichlorodiphenylsilane
*8.4 mL, 40 mmol). The resulting slurry was brought to
re¯ux and stirred for 1 h, allowed to cool, and concentrated
in vacuo. The residue was triturated with Et2O, and the Et2O
solution was concentration in vacuo. Vacuum distillation
*115±1208C, 0.4 mm Hg) gave chlorosilane *5.02 g, 17.7
mmol, 43%) as a colorless viscous oil. To a cooled *08C)
solution of allyl alcohol *3.6 mL, 53.0 mmol) and Et3N
*7.5 mL, 53.9 mmol) in DCM *15 mL) was slowly added
chlorosilane *5.02 g, 17.7 mmol). The reaction mixture
was stirred at rt for 45 min, diluted with hexane *50 mL),
®ltered through celite, and concentrated in vacuo. Vacuum
distillation *120±1258C, 0.4 mm Hg) gave 5,5-diphenyl-4-
oxa-5-sila-1-decen-6-yne *1.02 g, 3.33 mmol) as a colorless
oil in 19% yield. Rf 0.58 *10% EtOAc/hexanes); IR *thin
®lm) n 3069 *s), 2963 *s), 2726 *w), 2359 *w), 2176 *s),
2. Reichwein, J. F.; Iacono, S. T.; Patel, M. C.; Pagenkopf, B. L.
Tetrahedron Lett. 2002 in press.
3. *a) Gauthier, D. R.; Zandi, K. S.; Shea, K. J. Tetrahedron
1998, 54, 2289±2338. *b) Fensterbank, L.; Malacria, M.;
Sieburth, S. M. Synthesis 1997, 813±854. *c) Bols, M.;
Skrydstrup, T. Chem. Rev. 1995, 95, 1253±1277.
4. Khand, I. U.; Pauson, P. L. J. Chem. Res. )M) 1977, 168±177.
5. Magnus, P.; Principe, L. M. Tetrahedron Lett. 1985, 26,
4851±4854.
6. *a) Yamanaka, M.; Nakamura, E. J. Am. Chem. Soc. 2001,
123, 1703±1708. *b) de Bruin, T. J. M.; Milet, A.; Robert,
F.; Gimbert, Y.; Greene, A. E. J. Am. Chem. Soc. 2001, 123,
7184±7185.
1
1590 *m), 1116 *s) cm21; H NMR *300 MHz, CDCl3) d
7.80±7.28 *m, 10H), 6.09±5.96 *m, 1H), 5.43±5.36 *m,
1H), 5.19±5.15 *m, 1H), 4.39±4.37 *m, 2H), 2.37 *t, Jˆ
7.2 Hz, 2H), 1.70±1.63 *m, 2H), 1.07 *t, Jˆ7.4 Hz, 3H);
13C NMR *75 MHz, CDCl3) d 136.8, 135.2, 135.0, 134.4,
132.8, 130.7, 130.1, 128.1, 115.0, 111.8, 79.0, 64.3, 22.4,
22.1, 13.8.
7. Habermas, K. L.; Denmark, S. E.; Jones, T. K. Org. React.
1994, 45, 1±158.
8. Hoffmann, R. W. Chem. Rev. 1989, 89, 1841±1860.
9. *a) Lokey, R. S.; Mills, N. S.; Rheingold, A. L. Organometal-
lics 1989, 8, 1803±1805. *b) Hughes, R. P.; Tucker, D. S.;
Rheingold, A. L. Organometallics 1993, 12, 3069±3074.
10. The indicated cobalt oxidation states are for bookkeeping
purposes only and are not meant to convey any actual
information about their oxidation states.
1.1.29. 1,1-Diphenyl-6-propyl-3a,4-dihydro-1H,3H-cyclo-
penta[c][1,2]oxasilol-5-one .37). To a solution of Co2*CO)8
*1.25 g, 3.33 mmol) in Et2O *20 mL) was added 36 *1.02 g,
3.33 mmol). After stirring for 30 min at rt the reaction
mixture and concentrated in vacuo at rt. Flash chroma-
tography *SiO2, hexane) gave the Co2*CO)6 complex of
enyne 36 *1.84 g, 3.1 mmol) as a dark red brown viscous
oil in 93% yield. Rf 0.27 *hexanes). A solution of enyne
complex *155 mg, 0.26 mmol) in acetonitrile *4.0 mL) was
heated at re¯ux for 16 h under an atmosphere of CO. The
reaction was allowed to cool, volatiles were removed in
vacuo, and the residue was dissolved in CH2Cl2 and ®ltrated
through neutral Al2O3. Puri®cation by ¯ash chromatography
11. Jeong, N.; Hwang, S. H.; Lee, Y. S.; Chung, Y. K. J. Am.
Chem. Soc. 1994, 116, 3159±3160.
12. *a) Pagenkopf, B. L.; Livinghouse, T. J. Am. Chem. Soc. 1996,
118, 2285±2286. *b) Belanger, D. B.; O'Mahony, D. J. R.;
Livinghouse, T. Tetrahedron Lett. 1998, 39, 7636±7640.
*c) Belanger, D. B.; Livinghouse, T. Tetrahedron Lett. 1998,
39, 7641±7644. *d) Pagenkopf, B. L.; Belanger, D. B.;
O'Mahony, D. J. R.; Livinghouse, T. Synthesis 2000, 1009±
1019.

3822
J. F. Reichwein et al. / Tetrahedron 58 )2002) 3813±3822
13. Krafft, M. E.; Bonaga, L. V. R.; Hirosawa, C. J. Org. Chem.
2001, 66, 3004±3020.
Lett. 1987, 28, 917±920. Pagenkopf, B. L.; Lund, E. C.;
Livinghouse, T. Tetrahedron 1995, 51, 4421.
16. Hoye, T. R.; Suriano, J. A. J. Org. Chem. 1993, 58, 1659±
1660.
14. *a) Silica: Simonian, S. O.; Smit, W. A.; Gybin, A. S.;
Shashkov, A. S.; Mikaelian, G. S.; Tarasov, V. A.; Ibragimov,
I. I.; Caple, R.; Froen, D. E. Tetrahedron Lett. 1986, 27, 1245±
1248. *b) Amine N-oxides: Shambayati, S.; Crowe, W. E.;
Schreiber, S. L. Tetrahedron Lett. 1990, 31, 5289±5292.
*c) Amine N-oxides: Jeong, N.; Chung, Y. K.; Lee, B. Y.;
Lee, S.; Yoo, S. E. Synlett 1991, 204±206. *d) DMSO:
Chung, Y. K.; Lee, B. Y.; Jeong, N.; Hudecek, M.; Pauson,
P. L. Organometallics 1993, 12, 220±223. *e) Primary
amines: Sugihara, T.; Yamada, M.; Ban, H.; Yamaguchi,
M.; Kaneko, C. Angew. Chem., Int. Ed. Engl. 1997, 36,
2801±2804. *f) Sul®des: Sugihara, T.; Yamada, M.;
Yamaguchi, M.; Nishizawa, M. Synlett 1999, 771±773.
*g) Molecular sieves: Perez-Serrano, L.; Blanco-Urgoiti, J.;
Casarrubios, L.; Dominguez, G.; Perez-Castells, J. J. Org.
Chem. 2000, 65, 3513±3519.
17. *a) Endres, H. Comprehensive Coordination Chemistry;
Wilkinson, G., Gillard, R. D., McCleverty, J. A., Eds.;
Pergamon: Oxford, 1987; Vol. 2, pp 251±267. *b) Hay,
R. W. Comprehensive Coordination Chemistry; Wilkinson,
G., Gillard, R. D., McCleverty, J. A., Eds.; Pergamon: Oxford,
1987; Vol. 6, pp 411±485.
18. Crystallographic data for structures 31b and 32 have been
deposited with the Cambridge Crystallographic Data Center
as supplementary publication numbers CCDC 175779 and
179100, respectively. Copies of the data can be obtained,
free of charge, on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK [fax: 144*0)-1223-336033 or
email: deposit@ccdc.cam.ac.uk].
19. Cyclopentadienones of this sort often exists only in their
dimeric form, see: Ogliaruso, M. A.; Romanelli, M. G.;
Becker, E. I. Chem. Rev. 1965, 65, 261±367.
15. [Ir*COD)Cl]2´2*S)-tolBINAP: Shibata, T.; Takagi, K. J. Am.
Chem. Soc. 2000, 122, 9852±9853. Mo*CO)6: Jeong, N.;
Lee, S. J. Tetrahedron Lett. 1993, 34, 4027±4030.
[RhCl*CO)dppp]2: Jeong, N. Organometallics 1998, 17,
3642±3644. Evans, P. A.; Robinson, J. E. J. Am. Chem. Soc.
2001, 123, 4609±4610. Ru3*CO)12: Kondo, T.; Nobuyoshi, S.;
Okada, T.; Mitsudo, T. J. Am. Chem. Soc. 1997, 119, 6187±
6188. Morimoto, T.; Chatani, N.; Fukumoto, Y.; Murai, S.
J. Org. Chem. 1997, 62, 3762±3765. Cp2Ti: Hicks, F. A.;
Berk, S. C.; Buchwald, S. L. J. Org. Chem. 1996, 61, 2713±
2718. Cp2Zr: Negishi, E.; Cederbaum, F. R.; Takahashi, T.
Tetrahedron Lett. 1986, 27, 2829±2832. Negishi, E.;
Swanson, D. R.; Cederbaum, F. R.; Takahashi, T. Tetrahedron
20. Michelin, R. A.; Mozzon, M.; Bertani, R. Coord. Chem. Rev.
1996, 147, 299±338.
21. Stack, J. G.; Doney, J. J.; Bergman, R. G.; Heathcock, C. H.
Organometallics 1990, 9, 453±466.
22. Armarego, W. L. F.; Perrin, D. D. Puri®cation of Laboratory
Chemicals; 4th ed; Butterworth-Heinemann: Oxford, 1996.
23. See footnote 50 in: Gao, Y.; Hanson, R. M.; Klunder, J. M.;
Ko, S. Y.; Masamune, H.; Sharpless, K. B. J. Am. Chem. Soc.
1987, 109, 5765±5780.
24. Roh, Y.; Jang, H.-Y.; Lynch, V.; Bauld, N. L.; Krische, M. J.
Org. Lett. 2002, 4, 611±613.