Novel carbon-carbon bond-forming reactions using carbocations produced from substituted propargyl silyl ethers by the action of TMSOTf

Article abstract of DOI:10.1021/jo010157p

Highly useful carbon-carbon bond forming reactions using stable allenyl, propargyl, or allyl-propargyl hybrid cations have been developed. These carbocations could be generated from silyl 1-(π-donor)-substituted propargyl ethers by the action of trimethylsilyl trifluoromethanesulfonate in dichloromethane at -78 °C to room temperature and could be attacked nucleophilically by electron rich arenes, allylsilanes, or enol silyl ethers, giving rise to allenes, alkynes, and their derivatives. A novel method for regio- and stereoselective synthesis of conjugated enynes utilizing allyl-propargyl hybrid cations has also been established.

Full text of DOI:10.1021/jo010157p

J . Org. Chem. 2001, 66, 4635-4642
4635
Novel Ca r bon -Ca r bon Bon d -F or m in g Rea ction s Usin g
Ca r boca tion s P r od u ced fr om Su bstitu ted P r op a r gyl Silyl Eth er s
by th e Action of TMSOTf
Teruhiko Ishikawa,* Masamitu Okano, Toshiaki Aikawa, and Seiki Saito*
Department of Bioscience and Biotechnology, Faculty of Engineering, Okayama University, Tsushima,
Okayama, 700-8530, J apan
seisaito@biotech.okayama-u.ac.jp
Received February 8, 2001
Highly useful carbon-carbon bond forming reactions using stable allenyl, propargyl, or allyl-
propargyl hybrid cations have been developed. These carbocations could be generated from silyl
1-(π-donor)-substituted propargyl ethers by the action of trimethylsilyl trifluoromethanesulfonate
in dichloromethane at -78 °C to room temperature and could be attacked nucleophilically by electron
rich arenes, allylsilanes, or enol silyl ethers, giving rise to allenes, alkynes, and their derivatives.
A novel method for regio- and stereoselective synthesis of conjugated enynes utilizing allyl-
propargyl hybrid cations has also been established.
In tr od u ction
but only the limited methods for generating these cations
under nonsolvolytic and nonnucleophilic conditions have
been developed.5 It should be mentioned, however, that
the following propargylic cations or its equivalents are
highly pertinent to this issue: one is carbocations R to
cobalt-complexed alkynyl unit (I)6 and the other is
(benzene)-Cr(CO)3-stabilized propargyl cation (II).7 They
have provided a number of synthetic applications so far.
We have, therefore, developed a novel method for carbon-
carbon formation using allenyl or propargyl cationic
species which is more simple and direct than those so
far developed including I6 or II.7 Also certain emphasis
is placed on the development of a method for introducing
enyne functionality relying on such chemistry because
the enyne compounds are attracting much attention of
organic chemists with regard to their versatility and high
potential as a basic framework in transition metal
catalyzed cyclization processes, which is one of the
current topics in organic synthesis.8
Allenes, alkynes, and their derivatives have estab-
lished a reputation as increasingly popular intermediates
in modern organic synthesis1 because of their unique
structural characteristics and reactivities including ionic,
radical, or concerted processes. The most prevailing way
of carbon-carbon bond formation utilizing these com-
pounds involves their organometallic derivatives.2,3 On
the other hand, carbon-carbon bond formation by di-
rectly employing allenyl and propargyl cationic species
has not developed into a fascinating synthetic method.
Indeed, structural studies on propargyl or allenyl cations
generated from propargyl halides or alcohols under
solvolytic conditions have been extensively conducted,4
* To whom correspondence should be addressed. Fax: (+81)86-251-
8209.
(1) (a) Patai, S. The Chemistry of Ketenes, Allens, and Related
Compounds; Wiley: Chichester, 1980; Parts 1 and 2. (b) Schuster, H.
F.; Coppola, G. M. Allenes in Organic Synthesis; Wiley: New York,
1984. (c) Nagashima S.; K, Kanematsu K. J . Synth. Org. Chem., J pn.
1993, 51, 608-619. (d) Meliktan, G. G.; Nicholas, K. M. Modern
Acetylene Chemistry; Stang, P. J .; Diederich, F. Eds.; VCH: Weinheim,
Germany, 1995.
(2) For reviews, see: (a) Yamamoto, H. In Comprehensive Organic
Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford, 1991;
Vol. 2, Chapter 1.3. (b) Garratt, P. J . In Comprehensive Organic
Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford, 1991;
Vol. 3, Chapter 1.7. (c) Sonogashira, K. In Comprehensive Organic
Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford, 1991;
Vol. 3, Chapter 2.4. (d) Marshall, J . A. Chem. Rev. 2000, 100, 3163-
3186.
Resu lts a n d Discu ssion
In ter - a n d In tr a m olecu la r F r ied el-Cr a fts Rea c-
tion s. The expected carbocations could be generated on
treating substituted propargyl silyl ethers with trimeth-
(4) Richey, H. G., J r., Richey, J . M. Carbonium Ions; Olah, G. A.,
Schleyer, P. von R., Eds.; Wiley-Interscience, New York, 1970; Vol. II,
Chapter 21.
(3) The synthesis of allene compounds by means of CsC bond
formation using (I) organometallics, (II) [2,3] Wittig rearrangement,
and (III) [3,3] rearrangement: for (I), see: (a) Elsevier, C. J .; Vermeer,
P. J . Org. Chem. 1985, 50, 3042-3045. (b) Elsevier C. J .; Vermeer, P.
J . Org. Chem. 1989, 54, 3726-3730. (c) Alexakis, A.; Marek, I.;
Mangeney, P.; Normant, J . F. J . Am. Chem. Soc. 1990, 112, 8042-
8047; for review, see: (d) Takayama, Y.; Gao, Y.; Sato, F. Angew.
Chem., Int. Ed. Engl. 1997, 36, 851-853. (e) Wan, Z.; Nelson, S. G. J .
Am. Chem. Soc. 2000, 122, 10470-10471; for (II), see: (f) Huche, M.;
Cresson, P. Tetrahedron Lett. 1975, 367-368. (g) Cazes, B.; J ulia, S.
Synth. Commun. 1977, 7, 273-275. (h) Marshall, J . A.; Wang, X. J .
Org. Chem. 1990, 55, 2995-2996. (i) Marshall, J . A.; Robinson, E. D.;
Zapata, A. J . Org. Chem. 1989, 55, 5854-5855; for (III), see: (j) Mori.
K.; Nukada, T.; Ebata, T. Tetrahedron 1981, 37, 1343-1347. (k) Tsuboi,
S.; Masuda, T.; Takeda, A. J . Org. Chem. 1982, 47, 4478-4482. (l)
J ung, M. E.; Pontillo, J . Org. Lett. 1999, 1, 367-369. (m) Wood, L. J .;
Moniz, G. A. Org. Lett. 1999, 1, 371-374.
(5) (a) Mayr, H.; Ba¨uml, E. Tetrahedron Lett. 1983, 24, 357-360.
(b), Mayr, H.; Ba¨uml, E. Tetrahedron Lett. 1984, 25, 1127-1130.
(6) Nicholas, K. M. Acc. Chem. Res. 1987, 20, 207-214.
(7) Mu¨ller, T. J . J .; Nets, A. Organometallics 1998, 17, 3609-3614.
(8) For recent reviews for metal-catalyzed carbocyclization, see: (a)
Lautens, M.; Klute, W.; Tam, W. Chem. Rev. 1996, 96, 49-92. (b)
Schore, N. E. Chem. Rev. 1988, 88, 1081-1119. (c) Vollhardt, K. P. C.
Angew. Chem., Int. Ed. Engl. 1984, 23, 539-644. For recent review
for metal-catalyzed benzannulation, see: (d) Gevorgyan, V.; Yamamoto,
Y. J . Organomet. Chem. 1999, 576, 232-247. For metal-catalyzed
cycloisomerization, see: (e) Trost, B. M.; Haffner, C. D.; J ebaratnam,
D. J .; Krische, M. J .; Thomas, A. P. J . Am. Chem. Soc. 1999, 121, 6183-
6192 and references therein, and (f) Sturla, S. J .; Kablaoui, N. M.;
Buchwald, S. L. J . Am. Chem. Soc. 1999, 121, 1976-1977. For enyne
metathesis reactions, see: (g) Fu¨rstner, A.; Szillat, H.; Gabor, B.;
Mynott, R. J . Am. Chem. Soc. 1998, 120, 8305-8314 and references
therein.
10.1021/jo010157p CCC: $20.00 © 2001 American Chemical Society
Published on Web 05/25/2001

4636 J . Org. Chem., Vol. 66, No. 13, 2001
Ishikawa et al.
Ch a r t 1
Sch em e 3. In tr a m olecu la r F r ied el-Cr a fts
Rea ction s
Sch em e 1. P r op a r gyl or Allen yl Ca tion
In ter m ed ia te in Non a qu eou s Ma yer -Sch u ster
Rea r r a n gem en t
Sch em e 2. In ter m olecu la r F r ied el-Cr a fts
Rea ction s
exclusively to allenyl arenes 4a and 4b, respectively, with
perfect regioselectivity on the aromatic ring in quantita-
tive yield. On the other hand, 3c derived from secondary
alcohol furnished contrasting 3-(trimethylsilyl)propargyl
arene 5c exclusively in high yield. A steric factor seems
to play a role in selecting two pathways leading to 4 and
5.
A regiochemical problem of this kind could be con-
trolled in the case of an intramolecular version of
Friedel-Crafts alkylation (Scheme 3). Thus, propargyl
silyl ethers (6a sd ), easily prepared from m-methoxy-
benzyl propargyl ethers 10, led to the formation of allenyl
isochromane derivatives (7a sd ) in high yield for every
case with one exception which resulted in the substrate
decomposition (7b). No diastereoselectivity was observed
for 7c,d for which an sp-hybridized nature of the cationic
carbon of allenyl cation intermediate should be respon-
sible.12 Propargyl silyl ether 8, prepared from benzyl
phenyl ether 11, led to the formation of seven-membered
dibenzooxapane derivative 9. These reactions are highly
useful for the construction of carbon frameworks contain-
ing an aromatic ring subunit.
ylsilyl trifluoromethanesulfonate (TMSOTf) in dichlo-
romethane.9 Scheme 1 shows that propargyl (A) or allenyl
(B) cationic species may be intermediates in the Mayer-
Schuster rearrangement10 before being trapped by water
in the medium.
The type A or B cationic species generated under the
newly developed, nonsolvolytic conditions was expected
to be trapped by carbon nucleophiles. This idea was
rewarded when we examined the TMSOTf-promoted
Friedel-Crafts reaction11 between propargylic silyl ethers
(3a sc) and anisole as a nucleophilic partner (Scheme 2).
Treatment of 3a and 3b, prepared from the corresponding
propargylic tertiary alcohols, with TMSOTf in anisole led
(9) Noyori, R.; Murata, S.; Suzuki, M. Tetrahedron 1981, 37, 3899-
3910.
(10) (a) Meyer, K. H.; Schuster, K. Chem. Ber. 1922, 55, 819-823.
(b) S. Swaminathan, S.; Narayanan, K. V. Chem. Rev. 1971, 71, 429-
438.; for the mechanistic studies, see: (c) Edens, M.; Boerner, D.;
Roane, C.; Nass, D.; Schiavelli, M. D. J . Org. Chem. 1977, 42, 3403-
3408. (d) Andres, J .; Cardenas, R.; Silla, E.; Tapia, O. J . Am. Chem.
Soc. 1988, 110, 666-674.
(11) Olah, G. A.; Krishnamurti, R.; Prakash, G. K. S. In Compre-
hensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon:
Oxford, 1991; Vol. 3, Chapter 1.8.
In marked contrast to these results, silyl propargyl
ethers 1, 12, and 13 were not amenable to the electro-
(12) For 13C NMR spectroscopic determination with regard to the
hybrid structure of allenyl cation species, see: Siehl, H.-U.; Kaufmann,
F.-P. J . Am. Chem. Soc. 1992, 114, 4937-4939.

Novel Carbon-Carbon Bond-Forming Reactions
J . Org. Chem., Vol. 66, No. 13, 2001 4637
Ch a r t 2
Sch em e 5. Str a tegy of Con ju ga ted En yn e
Syn th esis fr om En on es or En oa tes
Sch em e 4. TMSOTf-Ca ta lyzed Allen yla tion s a n d
P r op a r gyla tion
mol % Nu) to give the corresponding allenylsilane deriva-
tives (16s18) in acceptable yields which, otherwise, seem
difficult to access. In these catalytic processes no acety-
lenic product was detected at all, while 3c afforded silyl
acetylene (19) exclusively. These regiochemical features
are very much similar to the case of intermolecular
Friedel-Crafts processes (see Scheme 2).
Syn th esis of Con ju ga ted En yn es. As already men-
tioned above, geometrically homogeneous conjugated
enynes or dienynes are highly useful compounds for the
short-cut construction of complex carbocyclic backbones.8
Hence, the development of methods for synthesizing such
functionality should be a fascinating goal. The concept
and realization of this task are summarized in Scheme
5. Trimethylsilyl 1-(alken-1-yl)propargyl ethers (B) avail-
able from R,â-unsaturated carbonyl compounds (A) have
proven promising to generate cationic species [pent-1-
en-4-yn-3-yl cation systems (C)] capable of reacting with
carbon nucleophiles regioselectively on treatment with
catalytic TMSOTf in dichloromethane to afford such an
important class of enynes or dienynes (D).13
philic CsC bond formation under the conditions shown
above, which resulted in the decomposition of the sub-
strates. Thus, in order for the electrophilic CsC bond
forming reaction to be successful, both σ-donor on the
terminal sp-carbon and at least one π-donor on the
propargylic sp3-carbon in the substrates are necessary:
1 has the geminal phenyl groups on the propargylic sp3-
carbon but no substituent on the terminal sp-carbon, and
both 12 and 13 carry the TMS group on the terminal sp-
carbon but no π-donor on the propargylic sp3-carbon.
In ter m olecu la r Tr a p p in g w ith Allylsila n es a n d
En ol Silyl Eth er . When such structural demand men-
tioned above is satisfied, cationic species generated under
nonsolvolytic conditions by the action of TMSOTf will be
so stable that they could be trapped with external
nucleophiles other than aromatic π-nucleophiles. The
synthetic potential of the cationic intermediates along
this line can be positively evaluated by the following
catalytic processes.
The TMSOTf-catalyzed coupling reactions of 3a or 3c
with other nucleophiles involving allyltrimethylsilane,
geranyltrimethylsilane (14), or enol silyl ether (15) are
summarized in Scheme 4. In these cases, only the
catalytic amount of TMSOTf (10s14 mol %) is required
because the catalytic cycle can be established by the
regeneration of a silyl triflate with a silyl cation liberated
from the nucleophiles. The reaction of 3a was nicely
effected under the given reaction conditions (150s200
The substrate trimethylsilyl ethers involve nonconju-
gated trimethylsilyl 1-ethynyl-2-cyclohexen-1-yl ethers
(20), trimethylsilyl [1-(alken-1-yl)-1-methyl]propargyl
ethers (21), and trimethylsilyl [1-(alken-1-yl)-1-ethynyl]-
propargyl ethers (22) to which we can uneventfully gain
access through 1,2-addition of acetylide anions to enones
or enoates which is outlined in Scheme 6. The reaction
of these trimethylsilyl ethers 21 and 22 with allyltrim-
ethylsilane (1.2 equiv) are summarized again in Scheme
6. Catalytic amount of TMSOTf (0.1 equiv) effected the
desired reaction (CH2Cl2/-30 °C) to give conjugated (E)-
dienynes containing cyclohexene unit (23), acyclic (Z)-
dienynes (24), and diendiynes (25), respectively, with
excellent regio- and stereoselectivity (only Z for 24). The
geometry of 24 was confirmed to be Z on the basis of NOE
experiments.
Such a stereochemical consequence can be explained
by invoking sterically less demanding nature of an
ethynyl group than a methyl group. The plausible mech-
anism for the formation of Z-24 is shown in Scheme 7.
Two routes can explain the exclusive formation of such
(13) For the synthesis of conjugated enynes, see: (a) Trost, B. M.;
Sorum, T. S.; Chan, C.; Harms, A. E.; Ru¨hter, G. J . Am. Chem. Soc.
1997, 119, 698-708. (b) Trost, B. M.; Frontier, J . J . Am. Chem. Soc.
2000, 122, 11727-11728.

4638 J . Org. Chem., Vol. 66, No. 13, 2001
Ishikawa et al.
fragmentary, observed 45 years ago by Braude15,16 for the
solvolytic reactions of [1-(alken-1-yl)-1-ethynyl]propargyl
alcohols in 60% aqueous dioxane containing hydrogen
chloride. Although water could be an ultimate nucleophile
in this instance, such a preliminary finding should have
led to an approach of synthesizing carbon chains that
contain a conjugated enyne functionality. However, no
effort was made to realize the carbon-carbon bond
formation using the cation system C until Nicholas17
disclosed that such was the case when the alkyne moiety
of B was converted to an alkyne-Co2(CO)6 complex: this
resulted not only in extraordinary stabilization of a cation
R to this cobalt complex but also in successful reaction
with various carbon nucleophiles to selectively afford
conjugated enynes with not Z but E geometry because of
the increasing steric bulkiness of this complex group. The
present approach to the conjugated (Z)-enynes, therefore,
may be irreplaceable.
Sch em e 6. TMSOTf-Ca ta lyzed Con ju ga ted En yn e
Syn th esis Usin g Tr im eth ylsilyl
1-(Alk en -1-yl)p r op a r gyl Eth er s a n d
Allyltr im eth ylsila n e
It should be noted that the conjugated Z-enynes are
potent intermediates which possess suitable functionality
locations for various intramolecular reactions. For ex-
ample, Pauson-Khand reaction18 of the dienyne 24a
proceeded to afford substituted bicyclo[4,3,0]nonadienones
29 and 30 as a separable mixture of diastereomers
(Scheme 9).19
Con clu sion
We have developed the highly useful CsC bond-
forming protocol through the reactions of allenyl, prop-
argyl, or propargyl-allyl hybrid cations with soft carbon
nucleophiles which features not only operational simplic-
ity but also versatility in terms of reaction types. The
allenes and enyne compounds available through this
process can serve as interesting intermediates for various
synthetic purposes. The newly developed conditions for
the regio- and stereoselective synthesis of the conjugated
enynes in this work may enable organic chemists to
design multifarious intramolecular cyclization reactions
directed to complex molecules. Further synthetic explora-
tions using the cations adjacent to the π framework of
multiple bonds including the development of a new enyne
cyclization process for natural products synthesis are
under active investigations.
a Z-enyne product.14 The reaction probably commences
with the formation of an oxonium ion-like intermediate
I1, which can dissociate to form cationic intermediate I2
rather than I3 for steric reason to be trapped by allylt-
rimethylsilane, giving rise to Z-24 (SN1-like mechanism).
On the other hand SN2′-like pathway can also lead to
Z-24 via transition state TS1 rather than TS2 again for
steric reason to lead to I4, direct precursor for Z-24.
Nucleophiles other than allyltrimethylsilane such as
enol silyl ether 15 or anisole can also be amenable to this
class of reaction with 20a and 21a to give the corre-
sponding conjugated enynes 26 and 27 or 28 in very high
yields and in a highly stereoselective manner again under
the given reaction conditions (Scheme 8).
Exp er im en ta l Section
1
Gen er a l Meth od s. H NMR spectra were recorded at 300
MHz and 13C NMR at 75 MHz using CDCl3 as a solvent unless
otherwise specified. The chemical shifts (δ) are given in parts
per million relative to internal CHCl3 (7.26 ppm for 1H) or
CDCl3 (77 ppm for 13C). The 1H NMR spectral data were
indicated in the form: δ-value of signal (peak multiplicity,
integrated number of protons, and coupling constant (if any)).
Splitting patterns are abbreviated as follows: s, singlet; d,
doublet; t, triplet; m, multiplet; br, broad. All the chemical shift
assignments were consistent with COSY spectra, and confor-
It should be pointed out that the SN2′-like nucleophilic
attack uniformly took place at C(1) of the present cation
system C (Scheme 7) with profoundly high regioselectiv-
ity to furnish the conjugated enynes 23-28. The regio-
chemical feature of the reaction of this class was, though
(15) Braude, E. A.; Coles, J . A.; Evans, E. A.; Timmons, C. J . Nature
1956, 177, 1167-1169.
(16) For related synthesis of enyne compounds under solvolytic
conditions, see: Descoins, C.; Samain, D. Tetrahedron Lett. 1976, 745-
748.
(14) At present stage of our research on this project we are thinking
that the SN2′-like route seems more plausible because the product-
determining transition states come earlier and more demanding than
the SN1-like route in which the product determining step comes after
the formation of I2 or I3, and their reactions with allyltrimethylsilane
seem less demanding. The final decision on this point, however, must
await future studies.
(17) Padmanabhan, S.; Nicholas, K. M. Tetrahedron Lett. 1982, 23,
2555-2558.
(18) For reviews, see: (a) Schore, N. E. Org. React. 1991, 40, 1-90.
(b) Schore, N. E. In Comprehensive Organic Synthesis; Trost, B. M.;
Fleming, I. Eds.; Pergamon: Oxford, 1991; Vol. 5, Chapter 9.1.
(19) The relative configurations of these cycloadducts were deter-
mined by careful analyses of 1H NMR spectra (J -value, NOE).

Novel Carbon-Carbon Bond-Forming Reactions
J . Org. Chem., Vol. 66, No. 13, 2001 4639
Sch em e 7. Mech a n ism of Con ju ga ted En yn e F or m a tion s for th e TMSOTf-Ca ta lyzed Rea ction betw een
Tr im eth ylsilyl 1-(Alk en -1-yl)p r op a r gyl Eth er s a n d Allyltr im eth ylsila n e
thickness). Column chromatography was performed on a
Merck silica gel 60 7734 using an appropriate ratio of ethyl
acetate-hexane mixed solvent and abbreviated as CC. El-
emental analyses were carried out by Dr. Miyoko Izawa of this
laboratory. All reactions, unless otherwise noted, were con-
ducted under a nitrogen or an argon atmosphere. Liquid
reagents are transferred via a dry hypodermic syringe and
added through a rubber septum wired onto a reaction flask
from which a steady stream of inert gas was flowing. Organic
extracts were concentrated by evaporation with a rotary
evaporator evacuated at around 60 mmHg. Unless otherwise
noted, materials were obtained from commercial suppliers and
reagent grade materials were used without further purifica-
tion. Triethylamine (Et3N), dichloromethane (CH2Cl2), and
dimethylformamide (DMF) were freshly distilled from CaH2
prior to use. Tetrahydrofuran purchased from Kanto Chemical
Co., Inc., is dehydrated and stabilizer-free grade and was used
as received.
Sch em e 8. TMSOTf-Ca ta lyzed Con ju ga ted En yn e
Syn th esis Usin g Tr im eth ylsilyl
1-(Alk en -1-yl)p r op a r gyl Eth er s a n d Va r iou s
Ca r bon Nu cleop h iles
O-(Tr im eth ylsilyl)-1,1-d ip h en yl-2-p r op yn -1-ol (1). To a
solution of 1,1-diphenyl-2-propyn-1-ol (1.411 g, 6.8 mmol) and
triethylamine (2.8 mL) in CH2Cl2 (15 mL) was added TMSOTf
(2.8 mL, 13.8 mmol, 2.0 equiv) at 0 °C. The reaction was stirred
at 0 °C for 25 min followed by the addition of water. The
mixture was extracted with several portions of ethyl acetate.
The combined organic layers were dried over Na2SO4 and
concentrated. Purification by CC (70:1 hexane/EtOAc) provided
1
1 (1.890 g, 99%); IR (film) 2950, 2100 cm-1; H NMR δ 0.10
(S, 9H), 2.90 (s, 1H), 7.19-7.32 (m, 6H), 7.54-7.58 (m, 4H);
13C NMR δ 1.54, 75.4, 76.7, 86.5, 125.9, 127.3, 128.0, 146.1.
3,3-Dip h en yl-2-p r op en -1-a l (2). To a solution of 1 (0.283
g, 1.0 mmol) in THF (5.0 mL) was added TMSOTf (0.18 mL,
1.0 mmol) at -78 °C. The mixture was stirred at -78 °C to
room temperature for 3 h followed by the addition of saturated
aqueous solution of sodium chloride at 0 °C. The mixture was
extracted with several portions of ethyl acetate, and the
combined organic layers were dried over Na2SO4 and concen-
trated. Purification by CC (30:1 hexane/EtOAc) provided 2
Sch em e 9. P a u son -Kh a n d Rea ction of
Rep r esen ta tive Con ju ga ted En yn e
1
(0.131 g, 46%). IR (film) 3056, 1667 cm-1; H NMR δ 6.61 (d,
1H, J ) 8.3 Hz), 7.20-7.55 (m, 10H), 9.35 (d, 1H, J ) 8.3 Hz);
13C NMR δ 127.2, 128.3, 128.5, 128.6, 129.4, 130.4, 130.7,
136.6, 139.7, 162.2, 193.5.
O-(Tr im eth ylsilyl)-3-tr im eth ylsilyl-1,1-d ip h en yl-2-p r o-
p yn -1-ol (3a ). To a solution of 1,1-diphenyl-2-propyn-1-ol
(10.66 g, 58 mmol) in THF (50 mL) was added butyllithium
(1.54 M in hexane, 114 mL, 176 mmol, 3.0 equiv) during 17
mational analyses and determination of configurations were
carried out on the basis of a combination of J values, NOE
data, and NOESY correlations. FT-IR spectra were recorded
using NaCl plates. Analytical thin-layer chromatography was
performed on Merck precoated silica gel 60 F-254 (0.25 mm

4640 J . Org. Chem., Vol. 66, No. 13, 2001
Ishikawa et al.
min at 0 °C. To the solution was added chlorotrimethylsilane
(30 mL, 236 mmol, 4.0 equiv). The reaction was stirred at room
temperature for 10 min followed by the addition of saturated
aqueous solution of sodium chloride at 0 °C. The mixture was
extracted with several portions of ethyl acetate, and the
combined organic layers were dried over Na2SO4 and concen-
trated. Purification by CC (100: 1 hexane/EtOAc) provided 3a
(16.68 g, 81%); bp 110-119 °C (0.02 mmHg); IR (film) 2950,
2110 cm-1; 1H NMR δ 0.17 (s, 9H), 0.29 (s, 9H), 7.21-7.36 (m,
5H), 7.59-7.64 (m, 5H); 13C NMR δ -0.3, 1.6, 75.7, 92.9, 108.0,
125.9, 127.0, 127.9, 146.51.
7.38 (m, 4H), 7.58-7.66 (m, 2H); 13C NMR (as a 1:1 diaster-
eomeric pair) δ 1.73, 26.0, (35.7, 35.8), (36.4, 36.5), 55.1, (70.7,
70.8), 71.4, 77.7, (83.8, 84.0), (90.2, 90.3), 113.0, 113.1, 120.0,
125.0, 127.1, 127.9, 129.2, 139.9, (147.0, 147.1), 159.8.
4-O-(3-Met h oxyb en zyl)-1-O-(t r im et h ylsilyl)-5,5-d im e-
th yl-1-p h en yl-2-h exyn e-1,4-d iol (6d ). To a solution of 10b
(0.304 g, 1.3 mmol) in THF (5 mL) was added butyllithium
(1.53 M in hexane, 1.2 mL, 1.8 mmol, 1.4 equiv) at 0 °C. After
stirring at 0 °C for 20 min, benzaldehyde (0.15 mL, 1.5 mmol,
1.2 equiv) was added to the mixture. The resulting solution
was stirred at 0 °C to room temperature for 2 h followed by
the addition of water. The mixture was extracted with several
portions of ethyl acetate, and the combined organic layers were
dried over Na2SO4 and concentrated. Purification by CC (15:1
hexane/EtOAc) provided 4-O-(3-methoxybenzyl)-5,5-dimethyl-
1-phenyl-2-hexyne-1,4-diol (0.267 g, 60%). To a solution of this
diol (0.204 g, 0.60 mmol) and triethylamine (3 mL) in CH2Cl2
(5 mL) was added TMSOTf (0.16 mL, 0.88 mmol, 1.5 equiv).
The solution was stirred at 0 °C to room temperature for 4 h
followed by the addition of water. The mixture was extracted
with several portions of ethyl acetate, and the combined
organic layers were dried over Na2SO4 and concentrated.
Purification by CC (100:1 hexane/EtOAc) provided 6d (0.166
g, 67%) as a 1:1 mixture of diastereomers; IR (film) 2970, 2100
cm-1; 1H NMR (as a 1:1 diastereomeric pair) δ (0.237, 0.244)-
(s, 9/2H for each), (1.01, 1.03) (s, 9/2H for each), (3.77, 3.78)
(s, 1/2H for each), (3.79, 3.80) (s, 3/2H for each), (4.44 and 4.48,
4.79 and 4.83) (ABq, 1H for each, J ) 4.7, 6.0 Hz), 5.59 (s,
1H), 6.80-6.94 (m, 3H), 7.22-7.40 (m, 4H), 7.50-7.56 (m, 2H);
13C NMR (as a 1:1 diastereomeric pair) δ 0.28, 26.0, (35.6, 35.7),
55.1, 64.6, 70.7, (77.5, 77.6), (83.8, 83,9), (87.1, 87.2), (113.0,
113.1), 120.0, 126.3, 126.4, (127.7, 127.8), 128.3, 129.2, 140.0,
(141.5, 141.6), 159.6.
1-Tr im eth ylsilyl-1-(4-m eth oxyp h en yl)-3,3-d ip h en yla l-
len e (4a ). To a solution of 3a (0.080 g, 0.23 mmol) and anisole
(0.2 mL, 1.84 mmol, 8 equiv) in CH2Cl2 (3 mL) was added
TMSOTf (0.04 mL, 0.22 mmol) at -78 °C. The solution was
stirred at -78 °C for 3 h followed by the addition of saturated
aqueous solution of NaHCO3. The mixture was extracted with
several portions of ethyl acetate, and the combined organic
layers were dried over Na2SO4 and concentrated. Purification
by CC (100:1 hexane/EtOAc) provided 4a (0.084 g, 100%); IR
1
(film) 2950, 1920 cm-1; H NMR δ 0.36 (s, 9H), 3.83 (s, 3H),
6.90-7.00 (m, 2H), 7.21-7.50 (m, 12H); 13C NMR δ -0.04,
55.2, 102.8, 106.6, 114.1, 126.7, 128.0, 128.4, 128.9, 136.9,
158.5, 209.1; exact mass, m/z 370.1741 (calcd for C25H26OSi
m/z 370.1753). Anal. Calcd for C25H26OSi: C, 81.03; H, 7.07.
Found: C, 81.14; H, 10.87.
4-O-(3-Meth oxyben zyl)-1-O-(tr im eth ylsilyl)-1,1-d ip h e-
n yl-2-bu tyn e-1,4-d iol (6a ). To a solution of 10a (0.89 g, 5.1
mmol) in THF (8 mL) was added butyllithium (1.53 M in
hexane, 4.3 mL, 6.6 mmol, 1.3 equiv) at 0 °C. After stirring at
0 °C for 15 min, benzophenone (0.98 g, 5.4 mmol, 1.1 equiv)
was added to the mixture. The resulting solution was stirred
at 0 °C to room temperature for 1.5 h followed by the addition
of water. The mixture was extracted with several portions of
ethyl acetate, and the combined organic layers were dried over
Na2SO4 and concentrated. Purification by CC (7:1 hexane/
EtOAc) provided 4-O-(3-methoxybenzyl)-1,1-diphenyl-2-butyne-
1,4-diol (1.37 g, 76%). To a solution of this diol (0.51 g, 1.4
mmol) and triethylamine (2 mL) in CH2Cl2 (4 mL) was added
TMSOTf (0.46 mL, 2.5 mmol). The resulting solution was
stirred at 0 °C to room temperature for 4 h followed by the
addition of water. The mixture was extracted with several
portions of ethyl acetate, and the combined organic layers were
dried over Na2SO4 and concentrated. Purification by CC (50:1
hexane/EtOAc) provided 6a (0.56 g, 91%); IR (film) 2960, 2110
7-Meth oxy-4-(2,2-d ip h en ylvin ylid en e)isoch r om a n (7a )-
. To a solution of 6a (0.087 g, 0.2 mmol) in CH2Cl2 (5 mL) was
added TMSOTf (0.035 mL, 0.2 mmol). The solution was stirred
at -78 °C for 3.5 h followed by the addition of saturated
aqueous solution of NaHCO3. The mixture was extracted with
several portions of ethyl acetate, and the combined organic
layers were dried over Na2SO4 and concentrated. Purification
by CC (30:1 hexane/EtOAc) provided 7a (0.054 g, 80%); IR
(film) 2970, 1910 cm-1;1H NMR δ 3.81 (s, 3H), 4.72 (s, 2H),
4.83 (s, 2H), 6.62 (d, 1H,J ) 2.8 Hz), 6.82 (dd, 1H, J ) 2.8, 8.5
Hz), 7.28-7.46 (m, 10H), 7.54 (d, 1H, J ) 8.5 Hz); 13C NMR δ
55.3, 67.7, 68.9, 101.0, 109.3, 114.0, 115.4, 120.4, 127.5, 127.8,
128.42, 128.45, 135.2, 136.5, 159.0, 201.6; exact mass, m/z
342.1627 (calcd for C24H22O2 m/z 342.1619). Anal. Calcd for
1
cm-1; H NMR δ 0.12 (s, 9H), 3.79 (s, 3H), 4.35 (s, 2H), 4.61
(s, 2H), 6.82-6.93 (m, 2H), 7.19-7.33 (m, 8H), 7.55-7.58 (m,
4H); 13C NMR δ 1.6, 55.1, 57.5, 71.5, 75.6, 84.3, 89.4, 113.1,
113.7, 120.3, 126.0, 127.2, 129.4, 138.9, 146.4, 159.7. Anal.
Calcd for C27H30O3Si: C, 75.31; H, 7.02. Found: C, 75.17; H,
7.23.
C
24H22O2: C, 84.18; H, 6.48. Found: C, 84.31; H, 6.22.
3-[2-(3-Meth oxyben zyloxy)ph en yl]-3-O-(tr im eth ylsilyl)-
1-tr im eth ylsilyl-1-bu tyn -3-ol (8). To a solution of salicyla-
ldehyde (0.85 mL, 8.0 mmol) in THF (5 mL) and DMF (5 mL)
was added sodium hydride (60% in oil, 360 mg, 8.9 mmol) at
0 °C. After stirring at 0 °C for 30 min, 3-methoxybenzyl
bromide (1.2 mL, 8.6 mmol) was introduced to the mixture at
0 °C. The resulting mixture was stirred at room temperature
for 24 h followed by the addition of water. The mixture was
extracted with several portions of ethyl acetate, and the
combined organic layers were dried over Na2SO4 and concen-
trated. Purification by CC (15:1 hexane/EtOAc) provided O-(3-
methoxybenzyl)salicylaldehyde 11 (1.92 g, 99%). To a solution
of trimethylsilylacetylene (0.25 mL, 1.77 mmol) in THF (5 mL)
was added butyllithium (1.53 M in hexane, 1.1 mL, 1.7 mmol)
at 0 °C. After stirring at 0 °C for 20 min, a solution of 11 (362
mg, 1.50 mmol) in THF (3 mL) was added to the mixture. The
resulting solution was stirred at 0 °C to room temperature for
2 h followed by the addition of chlorotrimethylsilane (0.28 mL,
2.24 mmol). The reaction was stirred at room temperature for
2 h followed by the addition of water. The mixture was
extracted with several portions of ethyl acetate, and the
combined organic layers were dried over Na2SO4 and concen-
trated. Purification by CC (70:1 hexane/EtOAc) provided 8
(0.322 g, 52%). IR (film) 2950, 2100 cm-1; 1H NMR δ 0.152 (s,
9H), 0.153 (s, 9H), 3.81 (s, 3H), 5.10 (s, 2H), 5.90 (s, 1H), 6.80-
7.75 (m, 7H); 13C NMR δ -0.21, -0.27, 55.2, 59.5, 69.9, 89.3,
5-O-(3-Met h oxyb en zyl)-2-O-(t r im et h ylsilyl)-6,6-d im e-
th yl-2-p h en yl-3-h ep tyn e-2,5-d iol (6c). To a solution of 10b
(0.39 g, 1.7 mmol) in THF (6 mL) was added butyllithium (1.53
M in hexane, 1.3 mL, 2.0 mmol, 1.2 equiv) at 0 °C. After
stirring at 0 °C for 15 min, acetophenone (0.21 mL, 1.8 mmol,
1.05 equiv) was added to the mixture at 0 °C. The resulting
solution was stirred at 0 °C to room temperature for 2.5 h
followed by the addition of water. The mixture was extracted
with several portions of ethyl acetate, and the combined
organic layers were dried over Na2SO4 and concentrated.
Purification by CC (10:1 hexane/EtOAc) provided 5-O-(3-
methoxybenzyl)-6,6-dimethyl-2-phenyl-3-heptyne-2,5-diol (0.38
g, 64%). To a solution of this diol (0.279 g, 0.79 mmol) and
triethylamine (2 mL) in CH2Cl2 (4 mL) was added TMSOTf
(0.21 mL, 1.16 mmol, 1.5 equiv) at 0 °C. The solution was
stirred at 0 °C for 1 h followed by the addition of water. The
mixture was extracted with several portions of ethyl acetate,
and the combined organic layers were dried over Na2SO4 and
concentrated. Purification by CC (70:1 hexane/EtOAc) provided
6c (0.309 g, 92%) as a 1:1 mixture of diastereomers; IR (film)
2970, 2100 cm-1;1H NMR (as a 1:1 diastereomeric pair) δ 0.15
(s, 9H), (1.04, 1.05)(s, 9/2H for each), (1.75, 1.76) (s, 3/2H for
each), 3.79 (s, 1H), 3.80 (s, 3H), (4.46 and 4.50, 4.81 and 4.85)
(ABq, 1H for each, J ) 4.9, 3.6 Hz), 6.80-7.00 (m, 3H), 7.20-

Novel Carbon-Carbon Bond-Forming Reactions
J . Org. Chem., Vol. 66, No. 13, 2001 4641
106.3, 111.8, 112.6, 113.1, 119.3, 120.9, 127.9, 129.0, 129.5,
129.8, 138.7, 155.1, 159.7.
1H, J ) 10.4, 17.6 Hz), 7.20-7.35 (m, 10 H); 13C NMR δ 1.4,
17.6, 23.5, 24.5, 25.7, 41.0, 45.4, 105.9, 108.4, 111.9, 126.27,
126.3, 127.7, 127.9, 128.3, 131.2, 137.5, 206.1; exact mass, m/z
400.2571 (calcd for C28H36Si m/z 400.2586). Anal. Calcd for
C28H36Si: C, 83.93; H, 9.06. Found: C, 84.15; H, 8.88.
4-Ben zoyl-4-m eth yl-3-tr im eth ylsilyl-1,3-d ip h en yl-1,2-
p en ta d ien e (18). To a solution of 3a (0.143 g, 0.41 mmol) and
15 (0.169 g, 0.64 mmol, 1.6 equiv) in dichloromethane (4 mL)
was added TMSOTf (0.01 mL, 0.055 mmol, 0.13 equiv) at -78
°C. The solution was stirred at -78 °C to room temperature
for 8 h followed by the addition of saturated aqueous solution
of NaHCO3. The mixture was extracted with several portions
of ethyl acetate, and the combined organic layers were dried
over Na2SO4 concentrated. Purification by CC (70:1 hexane/
EtOAc) provided 18 (0.100 g, 60%); IR (film) 1910, 1670
cm-1;1H NMR δ 0.06 (s, 9H), 1.59 (s, 6H), 7.10-7.16 (m, 2H),
7.26-7.42 (m, 11H), 7.86-7.94 (m, 2H); 13C NMR δ 0.6, 28.16,
28.18, 51.2, 108.0, 108.3, 126.9, 127.8, 127.9, 128.0, 128.4,
128.5, 129.77, 129.79, 132.0 (2C), 136.2, 136.5, 203.5, 205.3;
exact mass, m/z 410.2073 (calcd for C28H30OSi m/z 410.2066).
Anal. Calcd for C28H30OSi: C, 81.90; H, 7.36. Found: C, 81.81;
H, 7.21.
3-O-(3-Meth oxyben zyl)-1-p r op yn -3-ol (10a ). To a solu-
tion of 3-methoxybenzyl alcohol (3.51 g, 25.4 mmol) in THF
(15 mL) and DMF (15 mL) was added sodium hydride (60% in
oil, 1.24 g, 31.0 mmol, 1.2 equiv) at 0 °C. The solution was
stirred at 0 °C for 25 min followed by the addition of propargyl
bromide (2.5 mL, 28.1 mmol, 1.1 equiv). The solution was
stirred at 0 °C to room temperature for 2 h followed by the
addition of water, and extracted with several portions of ethyl
acetate. The combined organic layers were dried over Na2SO4
and concentrated. Purification by CC (30:1 hexane/EtOAc)
provided 10a (4.16 g, 93%); IR (film) 2970, 2100 cm-1; 1H NMR
δ 2.47 (t, 1H, J ) 2.5 Hz), 3.82 (s, 3H), 4.18 (d, 2H, J ) 2.5
Hz), 4.59 (s, 2H), 6.81-6.96 (m, 3H), 7.24-7.30 (m, 1H); 13C
NMR δ 54.9, 56.9, 71.2, 74.6, 79.5, 113.1, 113.4, 120.0, 129.2,
138.7, 159.5.
3-(3-Meth oxyben zyloxy)-4,4-d im eth ylp en tyn e (10b). To
a solution of 3-hydroxy-4,4-dimethylpentyne (0.452 g, 4.0
mmol) in THF (7 mL) and DMF (2.5 mL) was added sodium
hydride (60% in oil, 0.208 g, 5.2 mmol, 1.3 equiv) at 0 °C. After
stirring at 0 °C for 20 min, 3-methoxybenzyl bromide (0.60
mL, 4.3 mmol, 1.1 equiv) was added to the mixture. The
reaction was stirred at 0 °C to room temperature for 1 h
followed by the addition of water. The mixture was extracted
with several portions of ethyl acetate, and the combined
organic layers were dried over Na2SO4 and concentrated.
Purification by CC (50:1 hexane/EtOAc) provided 10b (0.928
1-(O-Tr im eth ylsilyl)-1-p h en yleth yn yl-2-cycloh exen -1-
ol (20a ). To a solution of phenylacetylene (0.69 mL, 6.24 mmol)
in THF (12 mL) was added butyllithium in hexane (1.56 M,
3.7 mL, 5.7 mmol) at 0 °C. The mixture was stirred at 0 °C for
5 min. To the mixture was added 2-cyclohexenone (0.50 mL,
5.2 mmol), and the stirring was continued at 0 °C for 20 min.
Chlorotrimethylsilane (1.3 mL, 10 mmol) was added to the
mixture, and the stirring was continued at 0 °C for 30 min.
The reaction was quenched by the addition of water, and the
resulting mixture was extracted with several portions of ethyl
acetate-hexane mixed solvent. The combined organic layers
were dried over Na2SO4 and concentrated. Purification by CC
(50:1 hexane/EtOAc) provided 20a (0.535 g, 38%) as a colorless
g, 99%); IR (film) 2960, 1610 cm-1 1H NMR δ 1.02 (s, 9H),
;
2.44 (d, 1H, J ) 2.0 Hz), 3.68 (d, 1H, J ) 2.0 Hz), 3.81 (s, 3H),
4.47 and 4.83 (ABq, 2H, J ) 12.1 Hz), 6.80-6.86 (m, 1H),
6.91-6.96 (m, 2H), 7.22-7.30 (m, 1H); 13C NMR δ 25.8, 35.3,
55.1, 70.7, 74.5, 76.6, 77.3, 81.6, 113.1, 120.0, 129.2, 139.8,
159.6.
O-(ter t-Bu tyld im eth ylsilyl)-2-m eth yl-1-p h en ylp r op en -
1-ol (15). To a solution of isobutyrophenone (0.745 g, 5.0 mmol)
in triethylamine (3 mL) and CH2Cl2 (4 mL) was added tert-
butyldimethylsilyl trifluoromethanesulfonate (1.7 mL, 7.4
mmol, 1.5 equiv). The solution was stirred at 0 °C to room
temperature for 2.5 h followed by the addition of saturated
aqueous solution of NaHCO3. The mixture was extracted with
several portions of ethyl acetate, and the combined organic
layers were dried over Na2SO4 and concentrated. Purification
by CC (100: 1 hexane/EtOAc) provided 15 (1.19 g, 90%); IR
(film) 2970, 1610 cm-1; 1H NMR δ -0.20 (s, 6H), 0.89 (s, 9H),
1.65 (s, 3H), 1.80 (s, 3H), 7.20-7.32 (m, 5H); 13C NMR δ -4.3,
18.2 (2C), 19.9, 25.8, 112.5, 127.1, 127.6, 129.3, 139.2, 143.6.
1-Allyl-1-tr im eth ylsilyl-3,3-d ip h en yla llen e (16). To a
solution of 3a (0.080 g, 0.23 mmol) and allyltrimethylsilane
(0.075 mL, 0.47 mmol, 2.0 equiv) in CH2Cl2 (3 mL) was added
TMSOTf (0.005 mL, 0.028 mmol, 0.12 equiv) at -78 °C. The
solution was stirred at -78 °C for 20 min followed by the
addition of saturated aqueous solution of NaHCO3. The
mixture was extracted with several portions of ethyl acetate,
and the combined organic layers were dried over Na2SO4 and
concentrated. Purification by CC (300:1 hexane/EtOAc) pro-
vided 16 (0.055 g, 80%); IR (film) 2960, 1910 cm-1; 1H NMR δ
0.21 (s, 9H), 2.97 (dt, 2H, J ) 1.4, 6.6 Hz), 5.00-5.20 (m, 2H),
5.90-6.05 (m, 1H), 7.20-7.35 (m, 10H); 13C NMR δ 1.1, 34.4,
98.8, 105.3, 115.6, 126.4, 128.0, 128.3, 136.9, 137.6, 206.2; exact
mass, m/z 304.1635 (calcd for C21H24Si m/z 304.1647). Anal.
Calcd for C21H24Si: C, 82.83; H, 7.94. Found: C, 82.75; H, 8.07.
3-Tr im eth ylsilyl-4,8-dim eth yl-1,1-diph en yl-4-vin yl-1,2,7-
n on a tr ien e (17). To a solution of 3a (0.072 g, 0.20 mmol) and
geranyltrimethylsilane (0.066 g, 0.31 mmol, 1.5 equiv) in CH2-
Cl2 (3 mL) was added TMSOTf (0.005 mL, 0.028 mmol, 0.14
equiv) at -78 °C. The solution was stirred at -78 °C for 30
min followed by the addition of saturated aqueous solution of
NaHCO3. The mixture was extracted with several portions of
ethyl acetate, and the combined organic layers were dried over
Na2SO4 and concentrated. Purification by CC (hexane) pro-
vided 17 (0.057 g, 70%); IR (film) 2960, 1910 cm-1; 1H NMR δ
0.17 (s, 9H), 1.28 (s, 3H), 1.48 (s, 3H), 1.60-1.70 (m, 2H), 1.64
(s, 3H), 1.82-1.94 (m, 2H), 4.98-5.02 (m, 2H), 5.04 (dd, 1H, J
) 14.3, 17.6 Hz), 5.05 (dd, 1H, J ) 10.4, 14.3 Hz), 5.96 (dd,
1
oil. IR (film) 2953, 2112 cm-1; H NMR δ 0.25 (s, 9H), 1.75-
1.87 (m, 2H), 1.92-2.15 (m, 4H), 5.79-5.82 (m, 2H), 7.28-
7.35 (m, 3H), 7.38-7.44 (m, 2H); 13C NMR δ 2.1, 19.3, 24.7,
39.2, 67.1, 84.6, 93.3, 123.0, 128.1, 128.2, 131.4 (2C), 131.9.
3-(O-Tr im eth ylsilyl)-1-p h en yl-3-m eth yl-5-tr im eth ylsi-
lyl-1-p en ten -4-yn -3-ol (21a ). To a solution of trimethylsily-
lacetylene (1.0 mL, 7.2 mmol) in THF (15 mL) was added
butyllithium in hexane (1.50 M, 4.4 mL, 6.5 mmol) at 0 °C.
Benzalacetone (1.27 g, 8.68 mmol) was added to the mixture,
and the stirring was continued at 0 °C for 1 h. Chlorotrim-
ethylsilane was introduced to the mixture at 0 °C, and the
stirring was continued at 0 °C to room temperature for 1 h.
The reaction was quenched by the addition of water, and the
resulting mixture was extracted with several portions of ethyl
acetate-hexane mixed solvent. The combined organic layers
were dried over Na2SO4 and concentrated. The crude residue
was purified by CC (50:1 hexane/EtOAc) to give 21a (1.03 g,
1
45%) as a colorless oil. IR (film) 2950, 2110 cm-1; H NMR δ
0.258 (s, 9H), 0.264 (s, 9H), 1.65 (s, 3H), 6.26 (d, 1H, J ) 15.7
Hz), 6.82 (d, 1H, J ) 15.7 Hz), 7.24-7.47 (m, 5H); 13C NMR δ
-0.2, 2.0, 32.7, 69.6, 90.3, 108.0, 126.7, 127.6, 128.0, 128.5,
134.5, 136.6.
3-Met h yl-5-p h en yl-1-t r im et h ylsilyl-3(Z),7-oct a d ien -1-
yn e (24a ). To a solution of 21a (0.220 g, 0.695 mmol) and
allyltrimethylsilane (0.13 mL, 0.83 mmol) in CH2Cl2 (5 mL)
was added TMSOTf (0.013 mL, 0.070 mmol) at -30 °C. The
solution was stirred at -30 °C for 20 min. The reaction was
quenched by the addition of saturated aqueous solution of
NaHCO3, and the resulting mixture was extracted with several
portions of ethyl acetate-hexane mixed solvent. The combined
organic layers were dried over Na2SO4 and concentrated. The
crude residue was purified by CC (hexane) to give 24a (0.135
1
g, 72%) as a colorless oil. IR (film) 2950, 2120 cm-1; H NMR
δ 0.22 (s, 9H), 1.82 (d, 3H, J ) 1.5 Hz), 2.38-2.54 (m, 2H),
3.95 (dt, 1H, J ) 7.5, 9.6 Hz), 4.92-5.07 (m, 2H), 5.64-5.82
(m, 2H), 7.15-7.35 (m, 5H); 13C NMR δ 0.1, 22.8, 40.0, 46.6,
98.0, 104.7, 116.0, 118.0, 126.2, 127.4, 128.4, 136.4, 142.0,
144.0; exact mass, m/z 268.16475 (calcd for C18H24Si m/z
268.16472). Anal. Calcd for C18H24Si: C, 80.53; H, 9.01.
Found: C, 80.81; H, 8.87.

4642 J . Org. Chem., Vol. 66, No. 13, 2001
Ishikawa et al.
1
3-Meth yl-5-(4-m eth oxyp h en yl)-5-p h en yl-1-tr im eth ylsi-
lyl-3(Z)-p en ten -1-yn e (27). To a solution of 20a (0.068 g, 0.22
mmol) in CH2Cl2 (2 mL) was added anisole (0.035 g, 0.32 mmol)
at -30 °C. TMSOTf (0.004 mL, 0.02 mmol) was added to the
mixture, and the stirring was continued at -30 °C for 10 min.
The reaction was quenched by the addition of saturated
aqueous solution of NaHCO3, and the resulting mixture was
extracted with several portions of ethyl acetate-hexane mixed
solvent. The organic layers were dried over Na2SO4 and
concentrated. Purification by CC (30:1 hexane/EtOAc) provided
27 (0.069 g, 96%, Z:E ) 10:1) as a yellow oil; data for Z-isomer:
1689, 1540 cm-1; H NMR (500 MHz) δ 0.32 (s, 9H), 1.58 (dt,
1H, J ) 11.0, 13.1 Hz), 1.98 (dd, 1H, J ) 4.3, 18.0 Hz), 2.11
(q, 3H, J ) 1.2 Hz), 2.39-2.45 (m, 1H), 2.59 (dd, 1H, J ) 6.9,
18.2 Hz), 2.94-3.01 (m, 1H), 3.69s3.76 (m, 1H), 5.97-6.00
(m, 1H), 7.15-7.35 (m, 5H); 13C NMR δ 1.3, 22.9, 40.3, 41.9,
42.2, 44.7, 126.7, 127.4, 128.7, 132.9, 136.4, 139.1, 144.8, 181.9,
212.6; Anal. Calcd for C19H24OSi: C, 76.97; H, 8.16. Found:
C, 76.83; H, 8.11; Data for 30: IR (film) 2955, 1690, 1540 cm-1
;
1H NMR δ 0.31 (s, 9H), 1.87-2.10 (m, 6H), 2.44 (dd, 1H, J )
7.0, 18.0 Hz), 2.80-2.92 (m, 1H), 3.70-3.79 (b, 1H), 6.01-6.06
(m, 1H), 7.20-7.40 (m, 5H); 13C NMR δ 1.4, 23.0, 35.3, 37.6,
41.3, 42.0, 126.6, 128.1, 128.5, 133.5, 136.9 (2C), 143.5, 181.3,
212.6. Anal. Calcd for C19H24OSi: C, 76.97; H, 8.16. Found:
C, 76.81; H, 8.33.
1
IR (film) 3050, 2950, 2110 cm-1; H NMR δ 0.24 (s, 9H), 1.93
(d, 3H, J ) 1.4 Hz), 3.81 (s, 3H), 5.25 (d, 1H, J ) 10.2), 6.17
(dq, 1H, J ) 1.4, 10.2 Hz), 6.83-7.38 (m, 9H); 13C NMR δ 0.06,
22.9, 50.9, 55.2, 98.2, 104.4, 113.8, 118.5, 126.2, 128.2, 128.4,
129.2, 135.9, 140.5, 144.0, 158.0. Anal. Calcd for C25H30OSi:
C, 78.99; H, 7.83. Found: C, 78.82; H, 7.71.
4-P h en yl-2-m eth yl-9-(tr im eth ylsilyl)bicyclo[4.3.0]n on a-
2,9-d ien -8-on e (29 and 30). To a solution of 24a (0.124 g, 0.462
mmol) in CH2Cl2 (4 mL) was added cobalt octacarbonyl (0.189
g, 0.554 mmol), and the mixture was stirred at room temper-
ature for 1.5 h. The mixture was filtered through a Celite pad
and concentrated to give an acetylene-cobalt complex (0.256
g) in quantitative yield as a dark brown oil. A solution of the
acetylene-cobalt complex (0.133 g) in acetonitrile (4 mL) was
stirred at 62 to 70 °C for 6 h. The mixture was filtered through
silica gel and florisil pads and concentrated. Purification by
CC (20:1 hexane/EtOAc) provided 29 (0.027 g, 38%) and 30
(0.014 g, 20%) as a colorless oil. Data for 29: IR (film) 2954,
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for Scientific Research on Priority Areas
from the Ministry of Education, Science, Sports, and
Culture, J apan. We are also grateful to the SC-NMR
Laboratory of Okayama University for high-field NMR
experiments.
Su p p or tin g In for m a tion Ava ila ble: The copies of 1H
NMR and 13C NMR spectra of 4, 5, 7, 9, 16-19, 23-30 and
spectral data for compounds 3b,c, 4b, 5c, 7c,d , 9, 19, 20b,
21b, 22, 23, 24b, 25, 26, and 28. This material is available
free of charge via the Internet at http://pubs.acs.org.
J O010157P