Acetylenic vinyllithiums: Consecutive cycloisomerization-[4 + 2] cycloaddition reactions

Article abstract of DOI:10.1021/jo961437l

Acetylenic vinyllithiums (2), which were generated from the corresponding acetylenic vinyl bromides (3) by low-temperature lithium-bromine exchange, cyclize on warming to give, following quench with water, isomerically pure conjugated bis-exocyclic 1,3-dienes (1) in good to excellent yield. Both five-membered and six-membered outer-ring dienes may be prepared: 5-exo closure of an acetylenic vinyllithium, which proceeds with total stereocontrol via syn-addition to give the E-isomer of a five-membered outer-ring diene, tolerates aryl-, silyl-, or alkyl-substituents at the distal acetylenic carbon; the corresponding 6-exo process is less facile and seems to be confined to substrates bearing an anion-stabilizing substituent, such as phenyl or trimethylsilyl, at the terminal acetylenic carbon. The highly reactive bis-exocyclic 1,3-dienes serve as precursors to polycyclic materials through subsequent Diels-Alder reaction with a wide variety of dienophiles. The consecutive exchange-cyclization-cycloaddition methodology, which can be conducted in one pot without isolation of intermediates, provides an efficient, operationally simple, and diastereoselective route to diverse polycyclic ring systems.

Full text of DOI:10.1021/jo961437l

8216
J . Org. Chem. 1996, 61, 8216-8228
Acetylen ic Vin yllith iu m s: Con secu tive Cycloisom er iza tion -[4 +
2] Cycloa d d ition Rea ction s
William F. Bailey,*,1a Nanette M. Wachter-J urcsak,1a,b Mark R. Pineau,1a Timo V. Ovaska,*,1c
Rachel R. Warren,1c and Carl E. Lewis1c
Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-4060, and the Department
of Chemistry, Connecticut College, New London, Connecticut 06320-4196
Received J uly 29, 1996X
Acetylenic vinyllithiums (2), which were generated from the corresponding acetylenic vinyl bromides
(3) by low-temperature lithium-bromine exchange, cyclize on warming to give, following quench
with water, isomerically pure conjugated bis-exocyclic 1,3-dienes (1) in good to excellent yield. Both
five-membered and six-membered outer-ring dienes may be prepared: 5-exo closure of an acetylenic
vinyllithium, which proceeds with total stereocontrol via syn-addition to give the E-isomer of a
five-membered outer-ring diene, tolerates aryl-, silyl-, or alkyl-substituents at the distal acetylenic
carbon; the corresponding 6-exo process is less facile and seems to be confined to substrates bearing
an anion-stabilizing substituent, such as phenyl or trimethylsilyl, at the terminal acetylenic carbon.
The highly reactive bis-exocyclic 1,3-dienes serve as precursors to polycyclic materials through
subsequent Diels-Alder reaction with a wide variety of dienophiles. The consecutive exchange-
cyclization-cycloaddition methodology, which can be conducted in one pot without isolation of
intermediates, provides an efficient, operationally simple, and diastereoselective route to diverse
polycyclic ring systems.
Intramolecular addition of an organolithium to an
the ring closure proceeds, as shown below, in a stereo-
selectively syn-fashion to give exocyclic vinyllithiums in
good yield.6,7
unactivated olefinic π-bond affords a convenient route to
a variety of carbocyclic and heterocyclic products.2-4
“Anionic” cyclizations5 of organolithiums bearing a re-
mote carbon-carbon triple bond have also been investi-
gated but the chemistry of such acetylenic systems is less
well developed than that of their olefinic counterparts.2
Studies of acetylenic alkyllithiums have established that
X Abstract published in Advance ACS Abstracts, November 1, 1996.
(1) (a) University of Connecticut. (b) Present address: Chemistry
Department, Hofstra University, Hempstead, NY 11550. (c) Con-
necticut College.
(2) Bailey, W. F.; Ovaska, T. V. In Advances in Detailed Reaction
Mechanisms; Coxon, J . M., Ed.; J AI Press: Greenwich, CT, 1994; Vol.
3, Mechanisms of Importance in Synthesis; pp 251-273.
In light of the excellent regio- and stereocontrol
observed in ring closures of acetylenic alkyllithiums, we
were prompted to investigate the synthetic utility of the
cyclization of acetylenic vinyllithiums. As detailed below,
exo-dig cycloisomerization of a vinyllithium tethered to
an acetylenic unit provides an experimentally simple
method for the preparation of synthetically useful bis-
exocyclic 1,3-dienes.8
A variety of bis-exocyclic 1,3-dienes have long been
known, and the rich cycloaddition chemistry of these
molecules has been well documented.9 More recently, a
number of transition-metal-catalyzed routes to such
“outer-ring” dienes have been developed,10 and these
approaches have largely supplanted classical elimination
(3) Bailey, W. F.; Patricia, J . J .; DelGobbo, V. C.; J arret, R. M.;
Okarma, P. J . J . Org. Chem. 1985, 50, 1999. (b) Bailey, W. F.; Nurmi,
T. T.; Patricia, J . J .; Wang, W. J . Am. Chem. Soc. 1987, 109, 2442. (c)
Bailey, W. F.; Rossi, K. J . Am. Chem. Soc. 1989, 111, 765. (d) Bailey,
W. F.; Khanolkar, A. D. J . Org. Chem. 1990, 55, 6058. (e) Bailey, W.
F.; Khanolkar, A. D. Tetrahedron Lett. 1990, 31, 5993. (f) Bailey, W.
F.; Khanolkar, A. D. Tetrahedron 1991, 47, 7727. (g) Bailey, W. F.;
Khanolkar, A. D.; Gavaskar, K.; Ovaska, T. V.; Rossi, K.; Thiel, Y.;
Wiberg, K. B. J . Am. Chem. Soc. 1991, 113, 5720. (h) Bailey, W. F.;
Punzalan, E. R.; Zarcone, L. M. J . Heteroatom Chem. 1992, 3, 55. (i)
Bailey, W. F.; Khanolkar, A. D.; Gavaskar, K. V. J . Am. Chem. Soc.
1992, 114, 8053. (j) Bailey, W. F.; Khanolkar, A. D. Organometallics
1993, 12, 239. (k) Bailey, W. F.; Gavaskar, K. V. Tetrahedron 1994,
50, 5957. (l) Bailey, W. F.; J iang, X.-L. J . Org. Chem. 1994, 59, 6528.
(m) Bailey, W. F.; J iang, X.-L.; McLeod, C. E. J . Org. Chem. 1995, 60,
7791. (n) Bailey, W. F.; J iang, X.-L. J . Org. Chem. 1996, 61, 2596.
(4) (a) Smith, M. J .; Wilson, S. E. Tetrahedron Lett. 1981, 22, 4615.
(b) Ross, G. A.; Koppang, M. D.; Bartak, D. E.; Woolsey, N. F. J . Am.
Chem. Soc. 1985, 107, 6742. (c) Cooke, M. P., J r. J . Org. Chem. 1992,
57, 1495 and references therein. (d) Chamberlin, A. R.; Bloom, S. H.;
Cervini, L. A.; Fotsch, C. H. J . Am. Chem. Soc. 1988, 110, 4788 and
references therein. (e) Broka, C. A.; Shen, T. J . Am. Chem. Soc. 1989,
111, 2981. (f) Krief, A.; Barbeaux, P. Synlett 1990, 511. (g) Krief, A.;
Kenda, B.; Barbeaux, P.; Guittet, E. Tetrahedron 1994, 50, 7177. (h)
Krief, A.; Kenda, B.; Remacle, B. Tetrahedron 1996, 52, 7435 and
references therein. (i) Lautens, M.; Kumanovic, S. J . Am. Chem. Soc.
1995, 117, 1954. (j) Zhang, D.; Liebeskind, L. S. J . Org. Chem. 1996,
61, 2594. (k) Coldham, I.; Hufton, R.; Snowden, D. J . J . Am. Chem.
Soc. 1996, 118, 5322.
(6) (a) Bailey, W. F.; Ovaska, T. V.; Leipert, T. K. Tetrahedron Lett.
1989, 30, 3901. (b) Bailey, W. F.; Ovaska, T. V. Tetrahedron Lett. 1990,
31, 627. (c) Wu, G.; Cederbaum, F. E.; Negishi, E. Tetrahedron Lett.
1990, 31, 493. (d) Bailey, W. F.; Ovaska, T. V. Chem. Lett. 1993, 819.
(e) Intramolecular addition of stabilized carbanions to alkoxyacetylenes
have also been reported: Funk, R. L.; Bolton, G. L.; Brummond, K.
M.; Ellestad. K. E.; Stallman, J . B. J . Am. Chem. Soc. 1993, 115, 7023.
(7) Bailey, W. F.; Ovaska, T. V. J . Am. Chem. Soc. 1993, 115, 3080.
(8) A preliminary account of this investigation has appeared, see:
Ovaska, T. V.; Warren, R. R.; Lewis, C. E.; Wachter-J urcsak, N. M.;
Bailey, W. F. J . Org. Chem. 1994, 59, 5868.
(9) Fringuelli, F.; Taticchi, A. Dienes in the Diels-Alder Reaction;
Wiley: New York, 1990.
(10) (a) Nugent, W. A.; Calabrese, J . C. J . Am. Chem. Soc. 1984,
106, 6422. (b) Nugent, W. A.; Thorn, D. L.; Harlow, R. L. J . Am. Chem.
Soc. 1987, 109, 2788. (c) Trost, B. M.; Lee, D. C. J . Org. Chem. 1989,
54, 2271. (d) Trost, B. M.; Shi, Y. J . Am. Chem. Soc. 1993, 115, 12491.
(e) Trost, B. M. Acc. Chem. Res. 1990, 23, 24 and references therein.
(f) Meyer, F. E.; Ang, K. H.; Steinig, A. G.; de Meijere, A. Synlett 1994,
191. (g) Grigg, R.; Sukirthalingam, S.; Sirdharan, V. Tetrahedron Lett.
1991, 32, 2545 and references therein.
(5) It should be noted that, although the ring closure of an olefinic
or acetylenic organolithium is often termed an anionic cyclization, the
lithium atom is intimately involved in the process and undoubtedly
serves to facilitate the cyclization. For a discussion of the unique role
of lithium in the cyclization of 5-hexenylalkalies, see: Bailey, W. F.;
Punzalan, E. R. J . Am. Chem. Soc. 1994, 116, 6577.
S0022-3263(96)01437-5 CCC: $12.00 © 1996 American Chemical Society

Acetylenic Vinyllithiums
J . Org. Chem., Vol. 61, No. 23, 1996 8217
sequences11 for the preparation of these very useful
intermediates. At the inception of the present study it
was anticipated, as illustrated below, that a bis-exocyclic
1,3-diene (1) could be constructed by cyclization of a
suitably constituted acetylenic vinyllithium (2) which, in
turn, would be generated from an acetylenic vinyl
bromide (3) by low-temperature lithium-halogen ex-
change. A major impetus for this approach was the
realization that the cyclization strategy, once reduced to
practice, could be coupled with the powerful Diels-Alder
reaction12 to provide a highly efficient and experimentally
simple route to a wide variety of complex polycyclic
systems. As demonstrated by the model studies de-
scribed below, this expectation was fully realized.
bromide substrates (4-14) were treated with t-BuLi
using these conditions,16 and this is the recommended
procedure for production of 2. As would be expected,7
the acetylenic vinyllithiums derived from bromides 4-14
are stable at low-temperature; quench of each reaction
mixture at -78 °C with oxygen-free MeOH delivered the
corresponding enyne in virtually quantitative yield.
With a convenient method in hand for the conversion
of acetylenic vinyl bromides to organolithiums, conditions
necessary to effect carbocyclization of the acetylenic
vinyllithiums were investigated. At the outset it was
clear that the facility of the cyclization would be depend-
ent on two factors: (1) the nature of the substituent
attached to the distal acetylenic carbon, and (2) the
length of the tether joining the vinyllithium to the
acetylenic unit. Studies of acetylenic alkyllithiums had
demonstrated that aryl- and silyl-substituted substrates
cyclize much more rapidly than do alkyl-substituted
analogs and that 5-exo-dig closures are invariably more
facile than 6-exo processes.7 Indeed, whereas the ring
closure of 6-phenyl-5-hexynyllithium is quite rapid even
at -50 °C, the analogous alkyl-substituted material,
5-decynyllithium, cyclizes some 106 times more slowly at
this low temperature.17 In view of the anticipated
sluggish isomerization of alkyl-substituted acetylenic
vinyllithiums and the expected difficulty of effecting
6-exo-dig closures, acetylenic vinyllithiums bearing alkyl
groups, as well as those giving a six-membered ring on
closure, were generated in solutions containing less
diethyl ether (i.e., 10:1 or 14:1 by vol of n-pentane-
diethyl ether) than is normally employed for the exchange
reaction15 so as to minimize inadvertent quench of the
organolithium by proton abstraction from the ether
solvent.
Cycloisomerizations were effected by simply allowing
solutions of the acetylenic vinyllithiums to warm and
stand for a period of time at an appropriate temperature
under an atmosphere of argon prior to the addition of
oxygen-free MeOH or water. Isomerization conditions
and the results of the cyclization experiments are sum-
marized in Table 1. Cursory inspection of the data
presented in Table 1 reveals that both five- and six-
membered bis-exocyclic 1,3-dienes may be generated by
this approach. Moreover, in all but one instance (vide
infra; Table 1, entry 10), the ring closures proceed in a
totally stereoselective fashion, via syn-addition of the
vinyllithium to the acetylenic moiety, to give an isomeri-
cally pure E-outer-ring diene. It should be noted that
the only byproduct detected in any of these reactions was
the open-chain enyne.
Resu lts a n d Discu ssion
P r ep a r a tion a n d Cycliza tion of Acetylen ic Vin yl-
lith iu m s. A representative selection of acetylenic vinyl
bromides (4-14), prepared for the most part in straight-
forward fashion by standard acetylide displacement
procedures,13 were selected to access the scope of the
cycloisomerization route to bis-exocyclic 1,3-dienes. Acet-
ylenic vinyllithiums 2 were generated at low-temperature
by addition of 2.0-2.2 molar equiv of tert-butyllithium
(t-BuLi) in pentane to an approximately 0.1 M solution
of the appropriate vinyl bromide (4-14) in a mixture of
n-pentane-diethyl ether. In the initial stages of this
investigation,8 the acetylenic vinyllithiums were prepared
at ∼-100 °C using a solvent system composed of n-pen-
tane-diethyl ether in an effort to avoid unwanted dehy-
drohalogenation of the base-sensitive substrates. Indeed,
pioneering studies by Seebach’s group of the reaction of
t-BuLi with vinyl bromides in solvent systems containing
THF have demonstrated that it is often necessary to
perform the exchange at temperatures below -110 °C to
minimize alkyne formation.14 For this reason, we were
delighted to subsequently discover that the acetylenic
vinyllithiums (2) may be cleanly generated by lithium-
bromine exchange at a more experimentally convenient
temperature of -78 °C following our general protocol15
provided that the solvent system is free of THF: there
was no evidence of dehydrohalogenation when the vinyl
More detailed analysis of the results presented in Table
1 indicates that the facility of the ring closure of an
acetylenic vinyllithium (2) is a strong function of the
group appended to the π-system. Thus, 5-exo cyclization
of substrates bearing either an aryl substituent (Table
1, entries 1, 4, and 5) or a trimethylsilyl-substituent
(Table 1, entries 2 and 3) proceed rapidly to give
conjugated, five-membered outer-ring dienes in 84-94%
isolated yield. The alkyl-substituted acetylenic vinyl-
lithiums derived from 7-alkyl-2-bromo-1-hepten-4-ynes
(11) See, for example: (a) Bailey, W. J .; Golden, H. R. J . Am. Chem.
Soc. 1953, 75, 4780. (b) Bailey, W. J .; Sorenson, W. R. J . Am. Chem.
Soc. 1954, 76, 5421. (c) Bloomquist, A. T.; Wolinsky, J .; Meinwald, Y.
C.; Congone, D. T. J . Am. Chem. Soc. 1956, 78, 6075. (d) van Straten,
J . W.; van Norden, J . J .; van Schaik, T. A. M.; Franke, C. T.; de Wolf,
W. N.; Bichelhaupt, F. Rec. Trav. Chim. Pays-Bas. 1978, 97, 105.
(12) The vast primary literature on the Diels-Alder reaction has
spawned an extensive number of reviews. A representative selection
of monographs may be found in: (a) Smith, M. B. Organic Synthesis;
McGraw-Hill: New York, 1994. (b) March, J . A. Advanced Organic
Chemistry, 4th ed.; Wiley Interscience: New York, 1992; pp 839-852.
(c) Holmes, H. L. Org. React. 1958, 4, 60.
(16) It would appear that the dehydrohalogenation reaction observed
by Seebach’s group14 when vinyl bromides are treated with t-BuLi at
-78 °C is a consequence of the presence of THF in such reaction
mixtures. The fact that alkyne formation is completely suppressed
when the exchange is conducted in solvent systems composed of
hydrocarbon and diethyl ether suggests that ether-solvated dimeric
t-BuLi may be responsible for the exchange while the THF-solvated
monomer may be responsible for the elimination reaction.15
(13) Brandsma, L. Preparative Acetylenic Chemistry; Elsevier: Am-
sterdam, 1988.
(14) (a) Seebach, D.; Neumann, H. Chem Ber. 1974, 107, 847. (b)
Neumann, H.; Seebach, D. Chem. Ber. 1978, 111, 2785.
(15) Bailey, W. F.; Punzalan, E. R. J . Org. Chem. 1990, 55, 5405.
(17) Bailey, W. F.; Ovaska, T. V. Organometallics 1990, 9, 1694.

8218 J . Org. Chem., Vol. 61, No. 23, 1996
Ta ble 1. Cycliza tion of Acetylen ic Vin yllith iu m s
Bailey et al.
(9-11) were far more resistant to rearrangement than
were the aryl- or silyl-substrates. Indeed, as detailed in
our preliminary report,8 5-exo cyclization of an alkyl-
substituted system does not proceed to an appreciable
extent when the acetylenic vinyllithiums are warmed to
room temperature in n-pentane-diethyl ether solution.

Acetylenic Vinyllithiums
J . Org. Chem., Vol. 61, No. 23, 1996 8219
Fortunately, the ring closure of an alkyl-bearing acety-
lenic vinyllithium is more facile when N,N,N ′,N ′-tet-
ramethylethylenediamine (TMEDA) is added prior to
warming. As demonstrated by the data presented in
Table 1 (entries 6-8), reasonable yields of isomerically
pure (E)-1-alkylidene-2-methylenecyclopentanes may be
realized by conducting the isomerization of the alkyl-
substituted systems in the presence of 2 molar equiv of
scrupulously dry and oxygen-free TMEDA at room tem-
perature for an extended period of time. It is perhaps
worth noting explicitly that rigorous exclusion of oxygen
and moisture is imperative to the success of ring closures
requiring day-long warming at room temperature.
The relative ease with which five-membered outer-
rings may be constructed via intramolecular carbolithia-
tion (Table 1, entries 1-8) prompted us to explore the
possibility of preparing six-membered rings by 6-exo-dig
cyclization. Not unexpectedly,7 this mode of ring closure
was more difficult to achieve than 5-exo cyclization to a
five-membered ring. Indeed, the 6-exo mode of ring
closure appears to be confined to substrates bearing an
anion-stabilizing aryl- or silyl-substituent on the terminal
acetylenic carbon; to date we have been unable to find
conditions that result in synthetically useful 6-exo-dig
cyclization of alkyl-substituted acetylenic vinyllithiums.
Be that as it may, cycloisomerization of the acetylenic
vinyllithiums derived from 2-bromo-8-phenyl-1-octen-7-
yne (12) and 2-bromo-8-(trimethylsilyl)-1-octen-7-yne (13)
were effected in good yield by simply allowing solutions
of the organolithiums in n-pentane-diethyl ether to
warm and stand at room temperature for several hours
under an atmosphere of argon (Table 1, entries 9, 10).
Cyclization of the organolithium prepared from 13 af-
forded the expected, isomerically pure, (E)-1-benzylidene-
2-methylenecyclohexane; however, 6-exo closure of the
silyl-substituted system gave an approximately 70:30
mixture of the diastereoisomeric E- and Z-outer-ring
dienes upon quench with water (Table 1, entry 10). As
illustrated below, the isolation of a mixture of isomeric
products from the later cyclization is undoubtedly a
consequence of cis-trans isomerization of the initially
formed E-isomer upon standing at 25 °C for 6 h. There
is ample precedent for the equilibration of silyl-substi-
tuted vinyllithiums at room temperature in ethereal
solvents and just such behavior has been documented in
studies of the cyclization of acetylenic alkyllithiums.7
acetylenic vinyllithium.19 Thus, as illustrated below, the
vinyllithium generated from bromide 14 cleanly cyclizes
with expulsion of the propargylic methoxy group to afford
the five-membered exocyclic allenene in 97% isolated
yield (Table 1, entry 11). This remarkably high-yield
intramolecular SN′ reaction is clearly the most direct
route to such exocyclic 1,2,4-trienes, and we are currently
exploring the possibility of preparing related conjugated
systems by this approach.
Diels-Alder Reaction s of 1,3-Bis-Exocyclic Dien es.
The efficient preparation of isomerically pure outer-ring
dienes provided by cycloisomerization of acetylenic vin-
yllithiums may be easily coupled with well-explored
Diels-Alder methodology to provide a simple, direct
route to more complex polycyclic ring systems. Intermo-
lecular Diels-Alder reactions of bis-exocyclic 1,3-dienes
are well precedented9-12 and the representative selection
of [4 + 2] cycloaddition reactions presented in Table 2
further illustrates the utility of these reactive dienes for
the synthesis of diverse ring structures. It might be
noted that no attempt was made to optimize conditions
for individual Diels-Alder reactions; adducts were pre-
pared by adding the dienophile (1 equiv) to the crude
outer-ring diene (1.1-1.5 equiv) in toluene or methylene
chloride solution. Indeed, an operationally important
feature of this methodology for the preparation of poly-
cyclic materials is the ability to conduct the entire three-
step operation (exchange-cycloisomerization-cycload-
dition) in one pot without purification (or even isolation)
of the intermediate bis-exocyclic 1,3-dienes. Although
yields are tabulated for intermediate dienes in Table 1,
the adducts listed in Table 2 were often prepared in one
flask by simply replacing the pentane-ether solvent with
toluene and adding the appropriate dienophile to the
crude bis-exocyclic 1,3-diene. In practice, isolation and
purification of the often crystalline cycloadduct is nor-
mally a fairly simple matter since the major byproducts
are variable amounts of the enyne formed by formal
reduction of the acetylenic vinyl bromide.
The intermolecular Diels-Alder reactions presented in
Table 2 proceeded in unexceptional fashion with the
expected cis-endo stereochemistry.9-12 The structures of
the adducts were for the most part established by
standard one- and two-dimensional NMR spectroscopy,
including NOE difference spectra and phase sensitive
The cyclization methodology described above may be
slightly modified to allow preparation of otherwise rela-
tively inaccessible exocyclic, conjugated allenenes18 (s-
annulated 1,2,4-trienes) by simple incorporation of a
leaving-group at the distal propargylic position of the
(18) For reviews of the preparation and reactions of conjugated
allenenes, see: (a) Landor, P. D. In The Chemistry of the Allenes;
Landor, S. R., Ed.; Academic Press: New York, 1982; Vol. 1, pp 205-
222. (b) Hopf, H. Ibid. Vol. 2, pp 563-576.
(19) The preparation of alkenylidenecycloalkanes by cyclization of
acetylenic alkyllithiums bearing a propargylic leaving group has been
described: see, Bailey, W. F.; Aspris, P. H. J . Org. Chem. 1995, 60,
754.

8220 J . Org. Chem., Vol. 61, No. 23, 1996
Ta ble 2. Diels-Ald er Rea ction s of Bis-1,3-Exocyclic Dien es
Bailey et al.

Acetylenic Vinyllithiums
J . Org. Chem., Vol. 61, No. 23, 1996 8221
Ta ble 2 (Con tin u ed )
NOESY experiments,20a and confirmed in the case of
adducts 15 (Table 2, entry 1) and 16 (Table 2, entry 6)
by single-crystal X-ray analyses8,20b (Figure 1).
Substrates suitable for intramolecular Diels-Alder
reaction21 may also be easily constructed by acetylenic
vinyllithium cyclization as illustrated by the example
(20) (a) Full details are available in the Ph.D. Dissertation of
Nanette M. Wachter-J urcsak, University of Connecticut, Storrs, CT,
1995. (b) Crystallographic data for 15: C19H20O3, a ) 10.448(2) Å, b )
12.119(2) Å, c ) 12.929(3) Å, R ) 74.84(3)°, â ) 86.36(3)°, γ ) 89.30-
(3)°, V ) 1576.9(5) Å3, space group ) P1h, molecules/unit cell ) 4,
F igu r e 1. Computer-generated rendering of the structures
of compounds 15 and 16 as determined by single-crystal X-ray
crystallography.20b
density (calcd) ) 1.248 g cm-3, linear absorption factor ) 0.668 mm-1
.
Crystallographic data for 16 appear in footnote 14 of ref 8. The
structures were solved by direct methods. The authors have deposited
atomic coordinates for 15 and 16 with the Cambridge Crystallographic
Data Center. The coordinates may be obtained, on request, from the
Director, Cambridge Crystallographic Data Center, 12 Union Road,
Cambridge, CB2 1EZ, UK.
presented in Scheme 1. The preparation of vinyl bromide
17 required for the generation of the acetylenic vinyl-

8222 J . Org. Chem., Vol. 61, No. 23, 1996
Bailey et al.
Sch em e 1
is tentatively assigned the cis-stereochemistry on the
basis of NMR data and literature precedent.10b,21
Con clu sion s
The results summarized in Table 1 demonstrate that
cycloisomerization of a vinyllithium tethered to an acety-
lenic unit provides a convenient, efficient route to five-
and six-membered bis-exocyclic 1,3-dienes. The 5-exo
closure, which proceeds with total stereocontrol to give
the E-isomer of a five-membered outer-ring diene, toler-
ates aryl-, silyl-, or alkyl-substituents at the distal
acetylenic carbon; the corresponding 6-exo process is less
facile and seems to be confined to substrates bearing an
anion-stabilizing substituent at the terminal acetylenic
carbon. As expected on the basis of prior art,9-12 the
outer-ring dienes react stereoselectively with a wide
range of dienophiles to give diastereoisomerically pure
polycyclic ring systems in good to excellent yield (Table
2). As a practical matter, it should be noted that
preparation of polycyclic products can be accomplished
without isolation of intermediates. As illustrated below,
the consecutive operations of exchange-cycloisomeriza-
tion-quench-cycloaddition (3 f 2 f 20 f 1 f 21) may
be conducted in one pot to deliver pure adducts in good
overall yield.
Sch em e 2
Exp er im en ta l Section
Gen er a l P r oced u r es. General spectroscopic and chro-
matographic procedures have been previously described.3g
NMR spectra were recorded as solutions in CDCl3, and all
chemical shifts are reported relative to Me4Si at δ ) 0.00.
Product mixtures were analyzed by GC on a 19-m × 0.25-mm
methyl phenyl (20%) silicone fused-silica capillary column and
by GC-MS on a 25-m × 0.20-mm cross-linked methyl silicone
fused-silica capillary column.
All operations involving organolithiums were performed in
flame-dried glassware using standard syringe/cannula tech-
niques under an atmosphere of dry, oxygen-free argon that
had been passed through a column containing an activated
BASF R3-11 copper catalyst. All liquids used for the prepara-
tion and quench of organolithiums that had not been freshly
distilled were rendered essentially oxygen free immediately
prior to use by bubbling dry, deoxygenated argon through the
neat liquid for a minimum of 5 min. The concentration of
commercial solutions of alkyllithium reagents (FMC) were
determined immediately prior to use by titration with standard
2-butanol in xylene using 1,10-phenanthroline as indicator
following the method of Watson and Eastham.24 Diethyl ether
and THF were freshly distilled from dark-purple solutions of
sodium/benzophenone. Dry, olefin-free n-pentane was ob-
tained by repeated washings of technical-grade n-pentane with
concentrated sulfuric acid until the acid layer remained clear,
followed by washing with water and saturated aqueous sodium
lithium was accomplished in 63% overall yield from
o-tolualdehyde as outlined in Scheme 2. Thus, allylation
of o-tolualdehyde following the elegant general procedure
of Comins and Brown22 gave the known 2-(3-butenyl)-
benzaldehyde23 which was then converted to 17 in
straightforward fashion (Scheme 2). Lithium-bromine
exchange between 17 and t-BuLi in n-pentane-diethyl
ether (4:1 by vol) solution at -78 °C afforded the
corresponding vinyllithium which cyclized upon warming
to 0 °C for 1 h (Scheme 1). Quench of the reaction
mixture with water delivered triene 18 in 75% yield.
Intramolecular [4 + 2]-cycloaddition, accomplished by
heating a benzene solution of 18 at 180 °C for 22 h,
proceeded in 75% yield to give tetracycle 19 as an
approximately 6:1 mixture of diastereoisomers (Scheme
1). The major product of the intramolecular cycloaddition
(21) (a) Ciganek, E. Org. React. 1984, 32, 1. (b) Oppolzer, W. Angew.
Chem., Int. Ed. Engl. 1977, 16, 10.
(22) Comins, D. L.; Brown, J . D. J . Org. Chem. 1984, 49, 1078.
(23) (a) Tietze, L.-F.; Kinast, G.; Uzar, H. Angew. Chem., Int. Ed.
Engl. 1979, 18, 541. (b) Martin, S. F.; Cheavens, T. H. Tetrahedron
Lett. 1989, 30, 7017.
(24) Watson, S. C.; Eastham, J . F. J . Organomet. Chem. 1967, 9,
165.

Acetylenic Vinyllithiums
J . Org. Chem., Vol. 61, No. 23, 1996 8223
bicarbonate, drying over MgSO4, and distillation of the purified
pentane under nitrogen from lithium aluminum hydride.
Literature procedures, incorporating some minor modifica-
tions, were followed for the preparation of 4-bromo-4-penten-
1-ol,25 ethyl 4-bromo-4-pentenoate,26 diethyl 2-(2-bromo-2-
propenyl)-2-(3-(trimethylsilyl)-2-propynyl)propanedioate,27
6-iodo-1-hexyne,28 and 1-ethynyl-1-methoxycyclohexane.29 The
previously reported gem-dibromides, 1-(2,2-dibromoethenyl)-
naphthalene,30 2-(2,2-dibromoethenyl)thiophene,31 and (2,2-
dibromoethenyl)cyclohexane,30 were converted, using the gen-
eral procedure of Corey and Fuchs,32 to the following known
acetylenes: 1-ethynylnaphthalene,33 2-ethynylthiophene,31 and
ethynylcyclohexane.30
2-Br om o-5-iod o-1-p en ten e. Following the general proce-
dure of Crossland and Servis,34 6.926 g (49.1 mmol) of 4-bromo-
4-penten-1-ol25 was converted into its mesylate. The crude
mesylate was added to a solution of 15.0 g (100 mmol) of dry
sodium iodide in 150 mL of dry acetone, and the mixture was
stirred overnight at room temperature under an atmosphere
of nitrogen and then at gentle reflux for 2 h. The mixture was
cooled, inorganic salts were removed by filtration, and the
precipitate was washed with three 50-mL portions of dry
acetone. The combined filtrate and washings were concen-
trated at reduced pressure, taken up in pentane, and washed
with 5% aqueous sodium thiosulfate. The organic layer was
dried (MgSO4) and concentrated at reduced pressure to give
10.804 g (94%) of the iodide as a colorless liquid: bp 77 °C
(2.2 mm); 1H NMR δ 2.06 (apparent pentet, J ) 6.82 Hz, 2 H),
2.56 (t, J ) 7.13 Hz, 2 H), 3.19 (t, J ) 6.67 Hz, 2 H), 5.47 (s,
1 H), 5.68 (s, 1 H); 13C NMR δ 4.88, 30.87, 41.56, 118.20,
132.04. Anal. Calcd for C5H8BrI: C, 21.84; H, 2.93. Found:
C, 22.07; H, 2.60.
reflux of the reaction mixture. After the addition was com-
plete, the mixture was heated at gentle reflux for 30 min. The
cooled reaction mixture was quenched with 9.00 mL of aque-
ous, saturated NH4Cl, the clear ethereal layer was separated,
and the white precipitate was continuously extracted with
diethyl ether for 14 h in a Soxhlet apparatus. The combined
ethereal extracts were concentrated at reduced pressure to give
4.04 g (87%) of product as a clear oil: 1H NMR δ 1.20 (s, 6 H),
1.60 (br s, 1 H), 1.66-1.72 (5 lines, 2 H), 2.46-2.52 (5 lines, 2
H), 5.34 (d, 1.62 Hz, 1 H), 5.54-5.57 (m, 1 H); 13C NMR δ 29.25,
36.55, 42.01, 70.34, 116.20, 134.79; IR (neat) 3394, 2972, 1629,
1467, 1377, 1150, 885 cm-1; HRMS calcd for C6H10BrO (M+
CH3) 176.9915, found 176.9912.
-
2,5-Dibr om o-5-m eth yl-1-h exen e. A mixture of 3.51 g
(18.2 mmol) of 5-bromo-2-methyl-5-hexen-2-ol and 0.384 g (4.85
mmol) of pyridine was placed in a 100 mL three-necked, round-
bottom equipped with a mechanical stirrer and a calcium
chloride drying tube, and the flask was immersed in an ice-
bath. To this cold solution was added 1.86 g (6.87 mmol) of
phosphorus tribromide via syringe over a period of 15 min.
After the addition was complete, the mixture was allowed to
warm and stir at room temperature for additional 30 min. The
apparatus was then set for downward distillation under
reduced pressure (3 mm) and the distillate boiling below 100
°C was collected. Redistillation of the crude product afforded
3.06 g (67%) of the dibromide as a clear liquid: bp 65-68 °C
1
(2.3 mm); H NMR δ 1.75 (s, 6 H), 2.01 (m, 2 H), 2.65 (m, 2
H), 5.39 (1 H, d, J ) 1.62 Hz); 13C NMR δ 35.0, 39.7, 46.6,
67.1, 117.9, 134.3; IR (neat) 2990, 2803, 1630, 1466, 1444,
1388, 1369, 1238, 1206, 1090, 880, 836 cm-1; HRMS calcd for
C7H12Br2 253.9306, found 253.9306.
2-Br om o-5,5-dim eth yl-7-ph en yl-1-h epten -6-yn e (4). The
general procedure of Negishi and Baba36 was followed for the
preparation of this compound. Thus, a solution of 3.38 g (33.1
mmol) of freshly distilled phenyl acetylene and 55 mL of dry
pentane was cooled under argon in an ice-bath, and 10.72 mL
of a 3.11 M solution of n-BuLi in hexane (33.35 mmol) was
slowly added via syringe. The mixture was stirred for 30 min
at 0 °C, and 1.47 g (11.04 mmol) of aluminum chloride was
then added in small portions over a period of 30 min. The
mixture was stirred for an additional 30 min period, and
solvents were then removed by rotary evaporation under an
atmosphere of dry nitrogen. The solid residue was cooled in
an ice-bath, 30 mL of dry methylene chloride was added to
dissolve the powdery solid, and 2.477 g (9.673 mmol) of 2,5-
dibromo-5-methyl-1-hexene in 55 mL of dry methylene chloride
was added in a dropwise fashion. The mixture was stirred at
0 °C for 1 h and then poured into 55 mL of ice-cold 10%
aqueous HCl. The aqueous layer was extracted with three 40-
mL portions of diethyl ether, and the combined organic layers
were washed once with brine and dried over MgSO4. Concen-
tration at reduced pressure afforded a brown liquid which was
purified by column chromatography (hexanes, Rf ) 0.14) to
give 2.10 g (78%) of product: bp (Kugelrohr) 135-140 °C (0.2
2-Br om o-6-iod o-1-h exen e. The general procedure of Su-
zuki and co-workers35 was followed to prepare the vinyl
bromide. Thus, 5.23 g (25.1 mmol) of 6-iodo-1-hexyne28 was
added at 0 °C under an atmosphere of nitrogen to 150 mL of
a solution of B-bromo-9-BBN prepared by adding 150 mL of
methylene chloride to 37.5 mL of a commercial 1.0 M solution
of B-bromo-9-BBN in methylene chloride. The solution was
stirred at 0 °C for 3 h, 15 mL of glacial acetic acid was then
added, and the mixture was stirred for an additional 1 h prior
to the sequential addition of 200 mL of 3 M aqueous sodium
hydroxide and 35 mL of 30% hydrogen peroxide. The mixture
was stirred for 1 h, the layers were separated, and the aqueous
layer was extracted with three 50-mL portions of hexanes. The
combined extracts were washed sequentially with 100 mL of
water, 100 mL of saturated, aqueous sodium bicarbonate, and
100 mL water. The organic layer was dried (MgSO4) and
concentrated at reduced pressure, and the residue was eluted
from a column of silica gel with hexanes to give 5.21 g (72%)
of the product: 1H NMR δ 1.62-1.71 (m, 2 H), 1.81 (apparent
pentet, J ) 6.79 Hz, 2 H), 2.43 (t, J ) 7.12 Hz, 2 H), 3.17 (t,
J ) 6.79 Hz, 2 H), 5.39 and 5.56 (AB pattern, J AB ) 1.37 Hz,
2 H); 13C NMR δ 5.97, 28.66, 32.05, 40.18, 116.99, 133.73. Anal.
Calcd for C6H10BrI: C, 24.94; H, 3.49. Found: C, 25.23; H,
3.55.
1
mm); H NMR δ 1.31 (s, 6 H), 1.70-1.78 (m, 2 H), 2.63-2.71
(m, 2 H), 5.40 (d, J ) 1.68 Hz, 1 H), 5.95-5.61 (m, 1 H), 7.25-
7.39 (m, 5 H); 13C NMR δ 29.20, 31.25, 38.03, 41.80, 81.05,
96.07, 116.23, 123.72, 127.57, 128.14, 131.54, 134.77; IR (neat)
3057, 2968, 2867, 1630, 1598, 1468, 1383, 1365, 1292, 1028,
886, 756, 692 cm-1. Anal. Calcd for C15H17Br: C, 64.99; H,
6.18. Found: C, 64.72; H, 6.48.
2-Br om o-7-(tr im eth ylsilyl)-1-h ep ten -6-yn e (5). A solu-
tion of 0.804 g (8.19 mmol) of (trimethylsilyl)acetylene in 25
mL of anhydrous THF was cooled to -78 °C under an
atmosphere of nitrogen, and 4.66 mL of a 1.56 M solution of
n-BuLi in hexane (7.27 mmol) was added over a period of 10
min. After stirring the reaction mixture at -78 °C for an
additional hour, 2.00 g (7.27 mmol) of 2-bromo-5-iodo-1-
pentene was added rapidly. The cooling bath was then
removed, and the mixture was allowed to warm to room
temperature and then heated at gentle reflux overnight. The
mixture was concentrated at reduced pressure, the residue was
partitioned between 20 mL of water and 20 mL of diethyl
ether, and the aqueous layer was extracted with three 15-mL
portions of diethyl ether. The combined organic layers were
5-Br om o-2-m eth yl-5-h exen -2-ol. A solution of 5.00 g (24.2
mmol) of ethyl 4-bromo-4-pentenoate26 in 13 mL of dry diethyl
ether was added to a solution of 52.5 mmol of methylmagne-
sium bromide in diethyl ether (prepared by adding 17.5 mL
of a 3.00 M solution of the Grignard reagent to 26 mL of
anhydrous diethyl ether) at such a rate as to maintain gentle
(25) Harris, G. D., J r.; Herr, R. J .; Weinreb, S. M. J . Org. Chem.
1993, 58, 5452.
(26) Groth, U.; Halfbrodt, W.; Koehler, T.; Kreye, P. Liebigs Ann.
Chem. 1994, 885.
(27) Crich, D.; Fortt, S. M. Tetrahedron Lett. 1987, 28, 2895.
(28) Myagkova, G. I.; Pyatnova, Yu. B.; Sarycheva, N. K.; Preo-
brazhenskii, N. A. Zh. Org. Khim. 1966, 2, 1998.
(29) Reference 13, p 263.
(30) Bestmann, H. J .; Frey, H. Liebigs Ann. Chem. 1980, 2061.
(31) Patrick, T. B.; Disher, J . M.; Probst, W. J . J . Org. Chem. 1972,
37, 4467.
(32) Corey, E. J .; Fuchs, P. L. Tetrahedron Lett. 1972, 36, 3769.
(33) Okuhara, K. J . Org. Chem. 1976, 41, 1487.
(34) Crossland, R. K.; Servis, K. L. J . Org. Chem. 1970, 35, 3195.
(35) Shoji, H.; Hidetaka, D.; Takinami, S.; Suzuki, A. Tetrahedron
Lett. 1983, 24, 731.
(36) Negishi, E.; Baba, S. J . Am. Chem. Soc. 1975, 97, 7385.

8224 J . Org. Chem., Vol. 61, No. 23, 1996
Bailey et al.
dried (MgSO4) and concentrated to give an oil which was
passed through a short plug of alumina eluting with pentane
to give, after solvent removal, 1.54 g (94%) of product: 1H NMR
δ 0.12 (s, 9 H), 1.73 (quintet, J ) 7.06 Hz, 2 H), 2.22 (t, J )
6.98 Hz, 2 H), 2.50 (apparent td, J t ) 7.16 Hz, J d ) 0.92 Hz,
2 H), 5.39 (apparent d, J ) 2.63 Hz, 1 H), 5.57-5.81 (m, 1 H);
13C NMR δ 0.09, 18.39, 26.46, 40.06, 85.26, 106.17, 117.31,
133.36; IR (neat) 2940, 2895, 2190, 1640, 1440, 1260, 850, 750
cm-1; HRMS calcd for C7H8Br (M+ - Me3Si) 170.9809, found
170.9806.
2-(2-Br om o-2-p r op en yl)-2-(3-(t r im et h ylsilyl)-2-p r op -
yn yl)-1,3-p r op a n ed iol. A solution of 3.80 g (9.76 mmol) of
diethyl 2-(2-bromo-2-propenyl)-2-(3-(trimethylsilyl)-2-prop-
ynyl)propanedioate27 in 15 mL of diethyl ether was added over
a 30 min period to a suspension of 1.65 g (43.6 mmol) of lithium
aluminum hydride in 75 mL of dry diethyl ether, and the
mixture was stirred for 30 min at room temperature. The
reaction mixture was cautiously hydrolyzed by sequential,
dropwise addition of 2.0 mL of water, 2.0 mL of 15% aqueous
sodium hydroxide, and 6.0 mL of water. The mixture was
filtered by gravity, and the white precipitate was washed well
with ether. Concentration of the combined filtrate and wash-
ings gave 2.98 g of diol (∼100% crude yield) which was used
for subsequent reactions: 1H NMR δ 0.11 (s, 9 H), 2.28 (s, 2
H), 2.63 (s, 2 H), 2.74 (broad s, 2 H), 3.65 (s, 2 H), 3.66 (s, 2
H), 5.58 (d, J ) 1.41 Hz, 1 H), 5.71-5.76 (m, 1 H); 13C NMR
δ -0.03, 22.85, 41.84, 43.25, 66.18, 88.38, 103.13, 121.90,
127.53; IR (neat) 3380, 2957, 2174, 1622, 1431, 1250, 1083,
1035, 842 cm-1; HRMS calcd for C12H21BrSiO2 304.0494, found
304.0495.
5-(2-Br om o-2-p r op en yl)-2,2-d im et h yl-5-(3-(t r im et h yl-
silyl)-2-p r op yn yl)-1,3-d ioxa n e (6). A solution of 1.52 g (4.98
mmol) of 2-(2-bromo-2-propenyl)-2-(3-(trimethylsilyl)-2-propy-
nyl)-1,3-propanediol, 0.620 g (5.96 mmol) of 2,2-dimethoxypro-
pane, and 2.4 mg of TsOH in 13 mL of benzene was distilled
until the still-head temperature reached 75 °C. The mixture
was then allowed to cool, and a small amount of anhydrous
potassium carbonate (∼10 mg) was added to neutralize the
acid catalyst. The mixture was filtered, the filtrate was
concentrated, and the residue was chromatographed over silica
gel (5% EtOAc/hexanes, Rf ) 0.14) to afford 1.50 g (87%) of
product: 1H NMR δ 0.13 (s, 9 H), 1.40 (s, 3H), 1.41 (s, 3 H),
2.50 (s, 2 H), 2.65 (s, 2 H), 3.77 (s, 4 H), 5.60 (d, J ) 1.38 Hz,
1 H), 5.72-5.76 (m, 1 H); 13C NMR δ 0.04, 22.50, 23.60, 25.04,
36.29, 43.57, 66.43, 88.29, 98.14, 103.13, 121.93, 127.07; IR
(neat) 2992, 2958, 2174, 1623, 1429, 1372, 1250, 1198, 1097,
843, 760 cm-1; HRMS calcd for C12H16BrO2 (M+ - Me3Si)
271.0333, found 271.0329.
mixture was heated at gentle reflux for 18 h, cooled to room
temperature, and then quenched with 25 mL of water. The
mixture was extracted with three 15-mL portions of diethyl
ether, the combined ethereal extracts were dried (MgSO4) and
concentrated, and the residue was distilled to give 8.02 g (83%)
1
of the product as a oil: bp 118-120 °C (0.7 mm); H NMR δ
1.78 (pentet, J ) 7.07 Hz, 2 H), 2.45 (t, J ) 7.07 Hz, 2 H),
2.58 (t of d, J ) 7.07, J ) 0.67 Hz, 2 H), 5.37 and 5.56 (AB
pattern, J AB ) 1.53 Hz, 2 H), 6.85-6.87 (m, 1 H), 7.04-7.10
(m, 2 H); 13C NMR δ 18.28, 26.52, 40.22, 74.44, 93.11, 117.39,
123.87, 126.01, 126.73, 131.02, 133.31. Anal. Calcd for
C11H11BrS: C, 51.78; H, 4.35. Found: C, 51.89; H, 4.44.
2-Br om o-7-cycloh exyl-1-h ep ten -6-yn e (9). A solution of
2.69 g (24.9 mmol) of ethynylcyclohexane in 25 mL of dry THF
was cooled to -78 °C under an atmosphere of nitrogen, and
19.0 mL of a 1.37 M solution of n-BuLi in hexanes (26.0 mmol)
was added. The cooling bath was removed, and the reaction
mixture was stirred at room temperature 1 h prior to the
addition of 5.92 g (21.5 mmol) of 2-bromo-5-iodo-1-pentene. The
mixture was then heated at gentle reflux for 14 h, cooled to
room temperature, and then partitioned between 10 mL of 5%
aqueous sodium thiosulfate and 40 mL of diethyl ether. The
aqueous layer was extracted with three 10-mL portions of
diethyl ether, and the combined ethereal layers were dried
(MgSO4) and concentrated at reduced pressure. The residue
was passed through a short silica gel column eluting with
hexanes (Rf ) 0.70) to afford 4.26 g (78%) of product: 1H NMR
δ 1.25-1.39 (m, 6 H), 1.65-1.77 (m, 6 H), 2.14-2.20 (t of d, J
) 6.88 Hz, J ) 2.16 Hz, 2 H), 2.38 (bs, 1 H), 2.51 (t, J ) 6.88
Hz, 2 H), 5.38 and 5.57 (AB pattern, J AB ) 1.40 Hz, 2 H); 13C
NMR δ 17.42, 24.90, 25.94, 27.19, 29.11, 33.12, 40.21, 78.80,
85.49, 116.98, 133.79. Anal. Calcd for C13H19Br: C, 61.19;
H, 7.50. Found: C, 61.03; H, 7.22.
2-Br om o-1-tr id ecen -6-yn e (10). A solution of 2.10 g (19.1
mmol) of 1-octyne in 20 mL of dry THF was cooled to -78 °C
under an atmosphere of nitrogen, and 13.6 mL of a 1.37 M
solution of n-BuLi in hexanes (18.6 mmol) was added. The
cooling bath was then removed, and the solution was stirred
at room temperature 30 min prior to the addition of 4.61 g
(16.8 mmol) of 2-bromo-5-iodo-1-pentene in 3 mL of dry HMPA.
The mixture was heated at gentle reflux for 16 h, cooled to
room temperature, and then partitioned between 10 mL of 5%
aqueous sodium thiosulfate and 40 mL of diethyl ether. The
aqueous layer was extracted with three 10-mL portions of
diethyl ether, the combined ethereal layers were dried (MgSO4)
and concentrated at reduced pressure, and the residue was
distilled to afford 3.54 g (82%) of product: bp 132-133 °C (2.4
1
mm); H NMR δ 0.85 (t, J ) 6.63 Hz, 3 H), 1.23-1.43 (m, 8
H), 1.69 (pentet, J ) 6.96 Hz, 2 H), 2.07-2.17 (m, 4 H), 2.50
(t, J ) 7.21 Hz, 2 H), 5.37 (apparent s, 1 H), 5.56 (apparent s,
1 H); 13C NMR δ 13.99, 17.45, 18.69, 22.54, 27.16, 28.52, 29.05,
31.34, 40.26, 78.90, 81.09, 116.93, 133.77. Anal. Calcd for
C13H21Br: C, 60.71; H, 8.23. Found: C, 60.73; H, 8.13.
2-Br om o-1-d ecen -6-yn e (11). A solution of 856 mg (12.6
mmol) of 1-pentyne in 11 mL of dry THF was cooled to -78
°C under an atmosphere of nitrogen, and 4.40 mL of a 3.46 M
solution of n-BuLi in hexanes (15.2 mmol) was added. The
cooling bath was removed, and the solution was stirred at room
temperature 30 min prior to the addition of 2.67 g (9.71 mmol)
of 2-bromo-5-iodo-1-pentene. The mixture was heated at
gentle reflux for 14 h, cooled to room temperature, and then
partitioned between 10 mL of 5% aqueous sodium thiosulfate
and 40 mL of diethyl ether. The aqueous layer was extracted
with three 10-mL portions of diethyl ether, the combined
ethereal layers were dried (MgSO4) and concentrated at
reduced pressure, and the residue was distilled to afford 1.90
g (92%) of product: bp 82 °C (1.5 mm); 1H NMR δ 0.95 (t, J )
7.33 Hz, 3 H), 1.50 (sextet, J ) 7.14 Hz, 2 H), 1.74 (pentet, J
) 7.16 Hz, 2 H), 2.16 (m, 4 H), 2.54 (t of d, J ) 7.24 Hz, J )
1.03 Hz, 2 H), 5.39 and 5.58 (AB pattern, J AB ) 1.52 Hz, 2 H);
13C NMR δ 13.43, 17.43, 20.71, 22.47, 27.16, 40.25, 79.07,
80.88, 116.98, 133.75. Anal. Calcd for C10H15Br: C, 55.83;
H, 7.03. Found: C, 55.89; H, 7.16.
2-Br om o-7-(1-n a p h th yl)-1-h ep ten -6-yn e (7). A solution
of 3.406 g (22.4 mmol) of 1-ethynylnaphthalene in 20 mL of
dry THF was cooled to -78 °C under an atmosphere of
nitrogen, and 16.0 mL of a 1.39 M solution of n-BuLi in
hexanes (22.2 mmol) was added. The cooling bath was then
removed, and the reaction mixture was stirred at room
temperature 30 min prior to the addition of 5.48 g (19.9 mmol)
of 2-bromo-5-iodo-1-pentene. The mixture was heated at
gentle reflux for 17 h, cooled to room temperature, and then
quenched with 15 mL of water. The mixture was extracted
with three 15-mL portions of diethyl ether, the combined
ethereal extract were dried (MgSO4) and concentrated, and
the residue was distilled to give 4.31 g (72%) of product: bp
1
175 °C (0.6 mm); H NMR δ 1.97 (pentet, J ) 7.15 Hz, 2 H),
2.61 (t, J ) 6.93, 2 H), 2.69 (t, J ) 7.20 Hz, 2 H), 5.47 (d, J )
1.49 Hz), 5.68 (d, J ) 1.49 Hz, 1 H), 7.37-7.85 (m, 6 H), 8.33
(apparent d, J ) 8.02 Hz, 1 H); 13C NMR δ 18.42, 26.99, 40.40,
79.39, 94.11, 117.43, 121.50, 125.21, 126.19, 126.24, 126.54,
128.07, 128.22, 130.09, 133.21, 133.50; IR (neat) 3065, 2980,
2220, 1613, 1570, 1410, 1378, 1098, 870, 780, 758 cm-1. Anal.
Calcd for C17H15Br: C, 68.24; H, 5.05. Found: C, 67.89; H,
5.02.
2-Br om o-7-(2-th ien yl)-1-h ep ten -6-yn e (8). A solution of
4.08 g (37.8 mmol) of 2-ethynylthiophene in 45 mL of dry THF
was cooled to -78 °C under an atmosphere of nitrogen and
29.8 mL of a 1.61 M solution of n-BuLi in hexanes (48.0 mmol)
was added. The cooling bath was then removed, and the
solution was stirred at room temperature 30 min prior to the
addition of 10.4 g (37.9 mmol) of 2-bromo-5-iodo-1-pentene. The
2-Br om o-8-p h en yl-1-octen -7-yn e (12). A solution of 2.07
g (20.3 mmol) of phenylacetylene in 15 mL of dry THF was
cooled to -78 °C under an atmosphere of nitrogen, and 13.0
mL of a 1.50 M solution of n-BuLi in hexanes (19.5 mmol) was

Acetylenic Vinyllithiums
J . Org. Chem., Vol. 61, No. 23, 1996 8225
added. The cooling bath was then removed, and the solution
was stirred at room temperature for 30 min prior to the
addition of 5.47 g (18.9 mmol) of 2-bromo-6-iodo-1-hexene. The
reaction mixture was heated at gentle reflux for 18 h, cooled
to room temperature, and then quenched with 15 mL water.
The mixture was extracted with three 10-mL portions of
diethyl ether, the combined ethereal extracts were dried
(MgSO4) and concentrated, and the residue was distilled to
give 4.66 g (94%) of the product as a pale yellow oil: bp 118-
(t, J ) 7.75 Hz, 2 H), 4.98-5.07 (m, 2 H), 5.80-6.00 (complex
pattern, 1 H), 7.25-7.90 (m, 4 H), 10.27 (s, 1 H); 13C NMR δ
31.91, 35.95, 114.43, 126.55, 131.04, 131.95, 133.63, 133.69,
137.36, 144.48, 192.34.
The aldehyde (3.08 g, 19.2 mmol) was added at 0 °C to a
solution of 12.4 g (37.5 mmol) of carbon tetrabromide and 19.6
g (103 mmol) of triphenylphosphine in 150 mL of methylene
chloride, and the mixture was stirred at 0 °C for 30 min and
then at room temperature for 40 min. Pentane (120 mL) was
then added, and the precipitate was removed by vacuum
filtration. The filtrate was concentrated under reduced pres-
sure, and the residue was passed through a short column of
silica gel using pentane as the eluent to give 5.89 g (97%) of
2-(3-butenyl)-1-(2,2-dibromoethenyl)benzene as a clear oil. The
dibromide (5.51 g, 17.4 mmol) was dissolved in 120 mL of
anhydrous THF, cooled to -78 °C, and treated with 36.2 mL
of a 1.80 M solution of n-BuLi in hexane (65.1 mmol). The
resulting mixture was stirred at -78 °C for 1 h. The reaction
was quenched by the addition of 0.60 mL of methanol followed
by 1.20 mL of water, the cooling bath was then removed, and
the mixture was allowed to warm to room temperature. The
bulk of the solvent was removed under reduced pressure, the
residue was partitioned between 20 mL of water and 100 mL
of pentane, the layers were separated, and the aqueous phase
was extracted with pentane. The combined pentane extracts
were dried (MgSO4) and concentrated to afford 2.76 g (∼100%)
of essentially pure title compound that was used as such for
subsequent reactions: 1H NMR δ 2.39 (apparent q, J ) 7.06
Hz, 2 H), 2.89 (apparent t, J ) 7.84 Hz, 2 H), 3.25 (s, 1 H),
4.95-5.08 (m, 2 H), 5.80-5.98 (complex pattern, 1 H), 7.11-
7.29 (m, 3 H), 7.46 (d, J ) 7.48 Hz, 1 H); 13C NMR δ 33.92,
34.52, 80.70, 82.24, 114.90, 121.48, 125.79, 128.78, 128.78,
132.88, 138.01, 144.44; IR (neat) 3295, 3072, 2927, 2104, 1641,
912, 756 cm-1; HRMS calcd for C12H12 156.0939, found 56.0935.
1
120 °C (0.7 mm); H NMR δ 1.50-1.69 (m, 4 H), 2.36 (t, J )
6.80 Hz, 2 H), 2.41 (t, J ) 6.94 Hz, 2 H), 5.34 and 5.52 (AB
pattern, J AB ) 1.19 Hz, 2 H), 7.19-7.36 (m, 5 H); 13C NMR δ
19.13, 27.02, 27.36, 40.85, 80.94, 89.68, 116.66, 123.89, 127.54,
128.17, 131.52, 134.30. Anal. Calcd for C14H15Br: C, 63.89;
H, 5.74. Found: C, 64.10; H, 5.75.
2-Br om o-8-(tr im eth ylsilyl)-1-octen -7-yn e (13). A solu-
tion of 2.66 g (27.1 mmol) of (trimethylsilyl)acetylene in 25
mL of dry THF was cooled to -78 °C under an atmosphere of
nitrogen, and 17.0 mL of a 1.77 M solution of n-BuLi in
hexanes (30.1 mmol) was added. The cooling bath was then
removed, and the solution was stirred at room temperature
for 30 min prior to the addition of 5.15 g (17.8 mmol) of
2-bromo-6-iodo-1-hexene. The mixture was heated at gentle
reflux for 17 h, cooled to room temperature, and then quenched
with 15 mL water. The mixture was extracted with three 15-
mL portions of diethyl ether, the combined ethereal extracts
were dried (MgSO4) and concentrated, and the residue was
distilled to give 4.39 g (96%) of product: bp 110-111 °C (2.5
1
mm); H NMR δ 0.12 (s, 9 H), 1.47-1.56 (m, 2 H), 1.59-1.68
(m, 2 H), 2.22 (t, J ) 6.92 Hz, 2 H), 2.42 (t, J ) 6.81 Hz, 2 H),
5.37 and 5.55 (AB pattern, J AB ) 1.46 Hz, 2 H); 13C NMR δ
0.14, 19.56, 26.90, 27.20, 40.81, 84.83, 106.90, 116.58, 134.31.
Anal. Calcd for C11H19BrSi: C, 50.96; H, 7.39. Found: C,
50.94; H, 7.63.
2-Br om o-7-(1-m eth oxycycloh exyl)-1-h ep ten -6-yn e (14).
A solution of 3.14 g (22.7 mmol) of 1-ethynyl-1-methoxycyclo-
hexane29 in 25 mL of dry THF was added to 14.0 mL of a 1.77
M solution of n-BuLi in hexanes (24.8 mmol) at room temper-
ature under an atmosphere of nitrogen, and the resulting
solution was warmed at gentle reflux for 1 h. The mixture
was then allowed to cool to room temperature, 4.96 g (18.1
mmol) of 2-bromo-5-iodo-1-pentene was added, and the result-
ing mixture was heated at reflux for 15 h. The reaction was
quenched with 20 mL of water and extracted with three 30-
mL portions of diethyl ether. The combined ethereal extracts
were dried (MgSO4) and concentrated, and the residue was
distilled to give 3.91 g (60%) of product: bp 147-149 °C (2.0
mm); 1H NMR δ 1.45-1.55 (m, 8 H), 1.72-1.82 (m, 4 H), 2.25
(t, J ) 6.87 Hz, 2 H), 2.53 (t, J ) 6.87 Hz, 2 H), 3.31 (s, 3 H),
5.39 and 5.57 (AB pattern, J AB ) 1.44 Hz, 2 H); 13C NMR δ
17.33, 22.87, 25.50, 26.94, 36.97, 40.20, 50.44, 73.94, 81.94,
85.11, 117.22, 133.52. Anal. Calcd for C14H21BrO: C, 58.96;
H, 7.42. Found: C, 59.29; H, 7.16.
2-(3-Bu ten yl)-1-eth yn ylben zen e. Following the general
procedure of Comins,22 a solution of 1.64 mL (12.8 mmol) of
N,N,N ′-trimethylethylenediamine in 32 mL of anhydrous THF
was cooled to -78 °C, and 8.05 mL of 1.54 M solution of n-BuLi
in hexane (12.4 mmol) was added under an atmosphere of
argon. After 30 min of stirring at -78 °C, 1.44 g (12.0 mmol)
of o-tolualdehyde was added and the solution was allowed to
warm to -20 °C over a period of 20 min. The mixture was
then cooled to -55 °C, and 21.8 mL of a 1.64 M solution of
t-BuLi in pentane (36.0 mmol) was added. The resulting dark-
red solution was stirred at -55 °C for 2.5 h and then recooled
to -78 °C, and 8.71 g (72.0 mmol) of allyl bromide was added
rapidly. The cooling bath was then removed, the colorless
reaction mixture was allowed to warm and stir at room
temperature for 30 min, and the mixture was then poured into
75 mL of cold 10% aqueous hydrochloric acid. The resulting
two-phase mixture was stirred rapidly for 10 min, and the
layers were separated. The aqueous layer was extracted with
three 50-mL portions of diethyl ether, and the combined
ethereal layers were washed with brine, dried (MgSO4), and
concentrated under reduced pressure. The residue was chro-
matographed over silica gel (5% EtOAc/n-pentane, Rf ) 0.26)
to give 1.36 g (71%) of the known23 2-(3-bu ten yl)ben za ld e-
h yd e as a clear oil: 1H NMR δ 2.33-2.39 (4 lines, 2 H), 3.14
2-Br om o-7-[2-(3-bu ten yl)p h en yl]-1-h ep ten -6-yn e (17).
A solution of 2.33 g (14.9 mmol) of 2-(3-butenyl)-1-ethynyl-
benzene in 53 mL of dry THF was cooled to -78 °C under an
atmosphere of nitrogen, and 8.29 mL of a 1.80 M solution of
n-BuLi in hexanes (14.9 mmol) was added. The cooling bath
was then removed, and the solution was stirred at room
temperature for 1 h prior to the addition of 4.10 g (14.9 mmol)
of 2-bromo-5-iodo-1-pentene. The mixture was heated at
gentle reflux for 16 h, cooled to room temperature, and then
quenched with water. The mixture was extracted well with
diethyl ether, the combined ethereal extracts were dried
(MgSO4) and concentrated, and the residue was purified by
column chromatography on silica gel using petroleum ether
(Rf ) 0.20) as eluent to afford 4.20 g (93%) of the product as a
clear oil: 1H NMR δ 1.86 (quintet, J ) 7.05 Hz, 2 H), 2.34-
2.43 (m, 2 H), 2.47 (t, J ) 6.93 Hz, 2 H), 2.61 (t, J ) 7.22 Hz,
2 H), 2.85 (m, 2 H), 4.94-5.10 (m, 2 H), 5.44 (apparent d, J )
1.39 Hz, 1 H), 5.62-5.64 (m, 1 H), 5.80-5.96 (10 lines, 1 H),
7.08-7.22 (m, 3 H), 7.36 (d, J ) 7.30 Hz, 1 H); 13C NMR δ
18.14, 26.85, 34.08, 34.55, 40.23, 79.86, 92.61, 114.76, 117.29,
123.07, 125.69, 127.65, 128.61, 132.15, 133.43, 138.08, 143.51;
HRMS calcd for C17H19 (M+ - Br) 223.1487, found 223.1484.
Gen er a l P r oced u r e for th e Gen er a tion a n d Cycliza -
tion of Acetylen ic Vin yllith iu m s. An approximately 0.1 M
solution of the appropriate acetylenic vinyl bromide (4-14, 17)
in n-pentane-diethyl ether (proportions as given in Table 1)
was cooled under an atmosphere of argon to either -100 °C
(bath temperature; MeOH-liq N2) or -78 °C (bath tempera-
ture; acetone-solid CO2) as indicated in Table 1, and, with
stirring, 2.0-2.2 molar equiv of commercial t-BuLi in pentane
was added via syringe over a 5 min period. The reaction
mixture was stirred for an additional 5 min at low tempera-
ture, and 2.0 molar equiv of dry, deoxygenated TMEDA was
added at -78 °C to reaction mixtures prepared from substrates
9-11 bearing an alkyl substituent on the triple bond (Table
1, entries 6-8). The reaction mixtures were then allowed to
stand under argon for a period of time at the appropriate
temperature to effect the isomerization: specific conditions of
time and temperature used to complete the cyclization of
various substrates are given in Table 1. Reaction mixtures
were quenched with either deoxygenated water or MeOH,
washed with water, dried (MgSO4), and concentrated. The
crude bis-exocyclic 1,3-dienes were used in subsequent Diels-

8226 J . Org. Chem., Vol. 61, No. 23, 1996
Bailey et al.
Alder reactions: the yields reported in Table 1 are those of
the dienes; the balance of the product, assayed by GC and H
NMR, was the isomeric uncyclized enyne. The dienes exhib-
ited the spectroscopic data presented below.
61.73, 62.08, 77.11, 80.84, 128.11, 128.24, 128.90, 130.61,
140.33, 141.75, 168.00, 168.93; IR (neat) 3087, 2954, 1746,
1
1495, 1456, 1364, 1259, 1182, 1043, 967, 858, 745, 700 cm-1
HRMS calcd for C22H28O5 372.1937, found 372.1933.
;
(E)-1-Ben zylid en e-5,5-d im eth yl-2-m eth ylen ecyclop en -
ta n e (Table 1, entry 1): 1H NMR δ 1.05 (s, 6 H), 1.53 (t, J )
7.49 Hz, 2 H), 2.47 (tt, J ) 7.49 Hz, J ) 2.39 Hz, 2 H), 4.88 (t,
J ) 2.09 Hz, 1 H), 5.40 (t, J ) 2.34 Hz, 1H), 6.99 (apparent s,
1 H), 7.21-7.32 (m, 5 H); 13C NMR δ 27.78, 29.25, 29.86, 41.74,
103.28, 120.27, 126.40, 127.60, 129.31, 138.27, 149.75, 151.54;
IR (neat) 3100, 3043, 2970, 2880, 1601, 1498, 1370, 963, 763,
701 cm-1; HRMS calcd for C15H18 198.1409, found 198.1409.
(3a r,4â,8a r)-5,5-Dim eth yl-4-p h en yl-4,5,6,7,8,8a -h exa h y-
d r o-3a H-2-oxa -5-in d a cen e-1,3-d ion e (15) (Table 2, entry 1).
A solution of 103 mg (0.519 mmol) of (E)-1-benzylidene-5,5-
dimethyl-2-methylenecyclopentane and 33.9 mg (0.346 mmol)
of maleic anhydride in 3 mL of toluene was heated at reflux
for 3 h. Removal of solvent at reduced pressure gave an off-
white solid which was recrystallized from hexanes to give 82
mg (80%) of product as colorless crystals: mp 157-158 °C; 1H
NMR δ 0.58 (s, 3 H), 1.06 (s, 3 H), 1.66-1.84 (m, 2 H), 2.28-
2.64 (m, 3 H), 2.94 (dd, J ) 18.23 Hz, J ) 1.58 Hz, 1 H), 3.30-
3.43 (m, 2 H), 3.93 (d, J ) 5.78 Hz, 1 H), 7.10-7.40 (m, 5 H);
13C NMR δ 21.85, 26.65, 27.21, 33.06, 38.05, 38.97, 39.46,
46.72, 47.04, 128.22, 128.52, 128.77, 133.20, 137.45, 141.85,
171.43, 173.83; IR (KBr) 3055, 3020, 2954, 1856, 1779, 1489,
1453, 1220, 1072, 746, 707 cm -1. Anal. Calcd for C19H20O3:
C, 76.99; H, 6.81. Found: C, 76.68; H, 7.05.
(E)-1-((Tr im eth ylsilyl)m eth ylid en e)-2-m eth ylen ecyclo-
p en ta n e (Table 1, entry 2):
1H NMR δ 0.11 (s, 9 H), 1.67
(apparent quintet, J ) 7.26 Hz, 2 H), 2.35-2.48 (m, 4 H), 4.86
(br s, 1 H), 5.34 (apparent t, J ) 2.26 Hz, 1H), 5.94 (t, J )
2.26 Hz, 1 H);
13C NMR δ 0.45, 24.04, 33.47, 33.58, 103.56,
116.85, 150.19, 156.48; IR (neat) 2954, 1595, 1312, 1247, 1043,
868, 841 cm-1
166.1175.
; HRMS calcd for C10H18Si 166.1178, found
2-P h en yl-4-(tr im eth ylsilyl)-5,6,7,8-tetr a h yd r o-4H-2,3a ,-
8a -tr ia za -5-in d a cen e-1,3-d ion e (Table 2, entry 5). To a
bright red solution of 54.5 mg (0.311 mmol) of 4-phenyl-1,2,4-
triazoline-3,5-dione in 3 mL of methylene chloride at 0 °C was
added 60.7 mg (0.365 mmol) of (E)-1-((trimethylsilyl)meth-
ylidene)-2-methylenecyclopentane and the resulting pale yel-
low mixture was stirred at 0 °C for 10 min. Removal of solvent
at reduced pressure gave a tan-colored solid which was
recrystallized from acetone to give 88.1 mg (83%) of the cyclo-
1
adduct: mp 123-124 °C; H NMR δ 0.12 (s, 9H), 2.00 (5 line
pattern, J ) 7.10 Hz, 2 H), 2.40 (t, J ) 7.10, 4 H), 4.00 (d, J
) 15.87 Hz, 1 H), 4.25 (d, J ) 15.87 Hz, 1 H), 4.31 (s, 1 H),
7.08-7.21 (m, 5 H); 13C NMR δ -1.77, 22.86, 32.96, 34.24,
46.30, 48.95, 125.37, 125.63, 127.93, 129.08, 131.49, 133.01,
149.68, 153.77; IR (KBr) 3014, 2954, 2899, 2848, 1772, 1711,
1600, 1502, 1455, 1417, 1250, 844, 762, 690 cm-1. Anal. Calcd
for C18H23N3O2Si: C, 63.31; H, 6.79; N, 12.30. Found: C,
63.18; H, 6.93; N, 12.35.
5,5-Dim eth yl-2,4-d ip h en yl-5,6,7,8-tetr a h yd r o-4H-2,3a ,-
8a -tr ia za -5-in d a cen e-1,3-d ion e (Table 2, entry 2). To a
bright-red solution of 83.4 mg (0.476 mmol) of 4-phenyl-1,2,4-
triazoline-3,5-dione in 3 mL of methylene chloride at 0 °C was
added 113 mg (0.570 mmol) of (E)-1-benzylidene-5,5-dimethyl-
2-methylenecyclopentane, and the resulting pale yellow mix-
ture was stirred at 0 °C for 10 min. Removal of solvent at
reduced pressure gave a tan-colored solid which was recrystal-
lized from acetone to give 133 mg (75%) of the cycloadduct:
(E)-2-((Tr im et h ylsilyl)m et h ylid en e)-3-m et h ylen e-7,9-
d ioxa sp ir o[4.5]d eca n e (Table 1, entry 3): 1H NMR δ 0.10
(s, 9 H), 1.39 (s, 3 H), 1.41 (s, 3 H), 2.35 (d, J ) 2.23 Hz, 2 H),
2.38 (t, J ) 2.18 Hz, 2 H), 3.58 (apparent s, 4 H), 4.85-4.89
(m, 1 H), 5.36 (t, J ) 2.28 Hz, 1 H), 5.96 (t, J ) 2.32 Hz, 1 H);
13C NMR δ -0.48, 23.32, 24.25, 38.93, 39.88, 40.11, 68.05,
97.87, 105.72, 119.32, 147.57, 153.69; IR (neat) 2953, 1640,
1600, 1370, 1248, 1198, 1100, 1063, 835 cm-1; HRMS calcd
for C15H26O2Si 266.1702, found 266.1701.
1
mp 179-180 °C; H NMR δ 0.56 (s, 3 H), 1.17 (s, 3 H), 1.80-
1.92 (m, 2 H), 2.41-2.56 (m, 2 H), 4.08 (d, J ) 16.64 Hz, 1 H),
4.55 (d, J ) 16.64 Hz, 1 H), 5.51 (s, 1 H), 7.25-7.45 (m, 10 H);
13C NMR δ 26.55, 27.39, 30.49, 40.44, 45.80, 56.96, 125.16,
127.80, 128.25, 128.43, 128.52, 128.76, 128.87, 131.09, 136.12,
139.90, 150.96, 152.68; IR (KBr) 3064, 2950, 2860, 1776, 1708,
1504, 1458, 1412, 1290, 1135, 767, 719, 697 cm-1. Anal. Calcd
for C23H23N3O2 C, 73.96; H, 6.21; N, 11.26. Found: C, 73.60;
H, 6.25; N, 11.08.
(4â,4ar,8ar)-2′,2′-Dim eth yl-4-(tr im eth ylsilyl)spir o(1,3,4,-
4a,5,8,8a,9-octah ydr ocyclopen ta[b]n aph th alen e-2,5′-[1,3]-
d ioxa n e)-5,8-d ion e (16) (Table 2, entry 6). A solution of 76.7
mg (0.288 mmol) of (E)-2-((trimethylsilyl)methylidene)-3-me-
thylene-7,9-dioxaspiro[4.5]decane and 208 mg (0.192 mmol) of
1,4-benzoquinone in 3 mL of toluene was heated at reflux for
4 h. Removal of solvent at reduced pressure gave a solid which
was recrystallized from a mixture of benzene and hexane to
give 64 mg (89%) of product as pale-yellow crystals: mp 152-
5-Ch lor o-1,1-d im eth yl-7-p h en yl-2,3,4,5,6,7-h exa h yd r o-
1H-in d en e-5-ca r bon itr ile (Table 2, entry 3). A solution of
83.3 mg (0.420 mmol) of (E)-1-benzylidene-5,5-dimethyl-2-
methylenecyclopentane and 24.5 mg (0.280 mmol) of 2-chlo-
roacrylonitrile in 5 mL of toluene was heated at gentle reflux
for 18 h. Solvent was removed at reduced pressure, and the
residue was chromatographed over silica gel (5% EtOAc/
hexanes; Rf ) 0.29) to give 68.0 mg (85%) of the cycloadduct
as a 7.2:1 mixture of diastereoisomers. The pale-yellow,
1
154 °C; H NMR δ 0.13 (s, 9 H), 1.39 (s, 3 H), 1.41 (s, 3 H),
1.61-1.69 (m, 1 H), 1.96-2.25 (m, 5 H), 2.38 (d, J ) 15.48 Hz,
1 H), 2.94-3.06 (m, 1 H), 3.48 (t, J ) 4.84 Hz, 1 H), 3.69-3.85
(m, 4 H), 6.56 (dd, J ) 10.27 Hz, J ) 1.66 Hz, 1 H), 6.65 (d, J
) 10.27 Hz, 1 H); 13C NMR δ 0.62, 23.53, 24.11, 28.00, 28.47,
30.89, 42.75, 42.94, 50.52, 69.15, 69.37, 97,69, 127.77, 132.13,
137.85, 140.59, 199.59, 202.42; IR (KBr) 2992, 2944, 2852,
1
1687, 1601, 1452, 1381, 1249, 1199, 1088, 1068, 835, 755 cm
Anal. Calcd for C21H30O4Si: C, 67.35; H, 8.08. Found:
C, 66.99; H, 8.45.
viscous liquid crystallized on standing: mp ) 81-83 °C; H
-1
.
NMR (major diastereoisomer) δ 0.57 (s, 3 H), 0.93 (s, 3 H),
1.60-1.78 (m, 2 H), 2.08-2.18 (m, 1 H), 2.25-2.37 (m, 5 H),
3.37 (s, 1 H), 7.25-7.37 (m, 5 H); 13C NMR 22.09, 25.46, 27.62,
29.68, 32.91, 39.49, 46.36, 50.82, 60.11, 118.97, 127.75, 128.35,
128.40, 133.45, 136.92, 137.85; HRMS calcd for C18H20ClN
285.1284, found 285.1288.
2′,2′-Dim eth yl-4-(tr im eth ylsilyl)sp ir o(4,7-d ih yd r o-1H-
in d en e-2,5′-[1,3]d ioxa n e)-5,6-d ica r boxylic Acid Dim eth yl
Ester (Table 2, entry 7). A solution of 77.7 mg (0.291 mmol)
of (E)-2-((trimethylsilyl)methylidene)-3-methylene-7,9-dioxa-
spiro[4.5]decane and 28.1 mg (0.198 mmol) of dimethyl acet-
ylenedicarboxylate in 3 mL of toluene was heated at reflux
for 3 h. Removal of the solvent at reduced pressure and
chromatography of the residue over silica gel (20 % EtOAc/
hexanes; Rf ) 0.40) gave 74.0 mg (91%) of a clear oil which
crystallized slowly on standing: mp 66-67 °C; 1H NMR δ
-0.01 (s, 9 H), 1.38 (s, 6 H), 2.03-2.34 (m, 4 H), 2.75-2.92
(m, 3 H), 2.63 (s, 2 H), 3.64 (s, 2 H), 3.69 (s, 3 H), 3.71 (s, 3 H);
13C NMR δ -1.57, 23.65, 23.83, 29.71, 34.73, 40.97, 42.32,
42.86, 51.96, 52.00, 69.13, 69.33, 97.65, 126.27, 130.69, 132.44,
137.58, 168.54, 168.97; IR (neat) 2992, 2951, 1728, 1437, 1384,
1265, 1198, 875, 833 cm -1. Anal. Calcd for C21H32O6Si: C,
61.74; H, 7.89. Found: C, 61.46; H, 8.02.
7,7-Dim eth yl-1-p h en yl-4,5,6,7-tetr a h yd r o-1H-cyclop en -
ta [c]p yr a n -3,3-d ica r boxylic Acid Dieth yl Ester (Table 2,
entry 4). A solution of 112.2 mg (0.566 mmol) of (E)-1-
benzylidene-5,5-dimethyl-2-methylenecyclopentane, 70.2 mg
(0.403 mmol) of diethyl ketomalonate, and 5.80 mg of 4-hy-
droxyphenol in 5 mL of toluene was heated at gentle reflux
for 2 h. Solvent was removed at reduced pressure, and the
residue was chromatographed over silica gel (15% EtOAc/
hexanes; Rf ) 0.20) to give 129 mg (86%) of the adduct as a
single regioisomer: 1H NMR δ 0.37 (s, 3 H), 0.97 (s, 3 H), 1.22
(t, J ) 7.12 Hz, 3 H), 1.30 (t, J ) 7.12 Hz, 3 H), 1.53-1.71 (m,
2 H), 2.13-2.28 (m, 1 H), 2.37-2.50 (m, 1 H), 2.81-2.84 (three
lines, 2 H), 4.10-4.31 (overlapping patterns, 4 H), 5.52
(apparent quintet, J ) 2.56 Hz, 1 H), 7.24-7.36 (m, 5 H); 13
NMR δ 13.91, 14.25, 26.87, 27.21, 31.30, 33.24, 40.43, 45.83,
C
(E)-2-(1-Na p h th ylm eth ylid en e)-1-m eth ylen ecyclop en -
ta n e (Table 1, entry 4): 1H NMR δ 1.74 (5 line pattern, J )

Acetylenic Vinyllithiums
J . Org. Chem., Vol. 61, No. 23, 1996 8227
7.15 Hz, 2 H), 2.55-2.66 (m, 4 H), 5.07 (apparent s, 1 H), 5.66
(apparent s, 1 H), 7.48-7.88 (m, 8 H); 13C NMR δ 24.52, 32.60,
33.76, 102.91, 116.67, 124.58, 125.26, 125.68, 125.79, 126.19,
127.18, 128.47, 131.96, 133.63, 135.22, 143.91, 150.33; HRMS
calcd for C17H16 220.1250, found 220.1252.
EtOAc/hexanes; Rf ) 0.56) gave 114.7 mg (74%) of the adduct
as an oil: 1H NMR δ 0.77-0.90 (m, 2 H), 1.00-1.25 (m, 4 H),
1.43-1.71 (m, 4 H), 1.79-1.89 (m, 2 H), 2.11-2.19 (m, 2 H),
2.27-2.46 (m, 3 H), 2.75-2.93 (m, 2 H), 3.15 (bs, 1 H), 3.68 (s,
3 H), 3.71 (s, 3 H); 13C NMR δ 22.87, 26.77, 27.03, 28.90, 29.32,
30.93, 35.09, 35.57, 42.62, 45.65, 51.98, 132.86, 133.16, 133.93,
138.97, 168.24, 169.76; HRMS calcd for C19H26O4 318.1821,
found 318.1824.
(3ar,4â,8ar)-4-(Naph th alen -1-yl)-4,5,6,7,8,8a-h exah ydr o-
3a H-2-oxa -5-in d a cen e-1,3-d ion e (Table 2, entry 8). A solu-
tion of 189 mg (0.86 mmol) of (E)-2-(1-naphthylmethylidene)-
1-methylenecyclopentane and 75.4 mg (0.769 mmol) of maleic
anhydride in 5 mL of toluene was heated at gentle reflux for
1.5 h. Evaporation of the solvent left a yellow solid which was
recrystallized from benzene to afford 184 mg (75%) of bone-
white crystals: mp 165-166 °C; 1H NMR δ 1.87 (5 line pattern,
J ) 7.48 Hz, 2 H), 2.12 (m, 2 H), 2.48-2.62 (m, 3 H), 3.02 (d,
J ) 17.85 Hz, 1 H), 3.45 (t of d, J ) 8.70 Hz, J ) 2.05 Hz 1 H),
3.72 (t, J ) 8.70 Hz, 1 H), 4.87 (d, J ) 7.57, 1 H), 7.02-7.84
(m, 6 H), 8.20 (d, J ) 8.37 Hz, 1 H); 13C NMR δ 19.72, 21.30,
21.66, 34.78, 35.86, 38.85, 45.08, 123.52, 125.17, 125.40,
125.87, 126.09, 128.83, 128.92, 132.21, 133.58, 134.16, 134.39,
170.63, 173.64. Anal. Calcd for C21H18O3: C, 79.22; H, 5.70.
Found: C, 78.93; H, 5.83.
(E)-2-Hep tylid en e-1-m eth ylen ecyclop en ta n e (Table 1,
entry 7): 1H NMR δ 0.85-0.99 (m, 3 H), 1.25-1.38 (m, 10 H),
1.79-1.45 (m, 2 H), 2.08 (t of d, J ) 6.97, J ) 14.32 Hz, 2 H),
2.31-2.42 (m, 2 H), 4.74 (s, 1 H), 5.19 (s, 1 H), 5.81-5.85 (m,
1 H); HRMS calcd for C13H22 178.1721, found 178.1721.
4-H exyl-2,3,4,7-t et r a h yd r o-1H -in d en e-5,6-d ica r b oxy-
lic Acid Dim eth yl Ester (Table 2, entry 12). A solution of
170.8 mg (0.958 mmol) of (E)-2-heptylidene-1-methylene-
cyclopentane and 131.3 mg (0.924 mmol) of dimethyl acety-
lenedicarboxylate in 5 mL of toluene was heated at gentle
reflux for 2 h. Removal of the solvent at reduced pressure and
chromatography of the pale-yellow residue over silica gel (20%
EtOAc/hexanes; Rf ) 0.78) gave 186.0 mg (63%) of the
adduct: 1H NMR δ 0.83-0.95 (m, 3 H), 1.11-1.29 (m, 8 H),
1.44-1.63 (m, 2 H), 1.90 (5 line pattern, 2 H), 2.14-2.40 (m,
4 H), 2.78-3.10 (m, 2 H), 3.32 (bs, 1 H), 3.76 (s, 3 H), 3.79 (s,
3 H); 13C NMR δ 14.02, 22.09, 22.60, 24.17, 28.62, 29.48, 30.77,
31.64, 33.22, 35.17, 39.53, 51.99, 52.04, 130.71, 131.86, 133.50,
140.94, 167.73, 169.80; HRMS calcd for C19H28O4 320.1988,
found 320.1989.
4-Na p h t h a len -1-yl-2,3,4,5,6,7-h exa h yd r o-1H -in d en e-
5,5,6,6-tetr a ca r bon itr ile (Table 2, entry 9). A solution of 185
mg (0.84 mmol) of (E)-2-(1-naphthylmethylidene)-1-meth-
ylenecyclopentane and 98.3 mg (0.767 mmol) of recrystallized
tetracyanoethylene in 5 mL of toluene was heated at gentle
reflux for 2 h. The reaction mixture was filtered through a
short plug of neutral alumina using diethyl ether as the eluent,
the solution was concentrated, and the residue triturated with
pentane to give a yellow solid. Recrystallization from pentane
(E)-2-Bu tylid en e-1-m eth ylen ecyclop en ta n e (Table 1,
entry 8): 1H NMR δ 0.82-1.01 (m, 3 H), 1.16-1.27 (m, 2 H),
1.37-1.45 (m, 2 H), 1.65 (t, J ) 7.24 Hz, 2 H), 2.02-2.38 (m,
4 H), 4.74 (apparent s, 1 H), 5.19 (apparent s, 1 H), 5.80-5.88
(m, 1 H); 13C NMR δ 14.05, 22.61, 23.97, 29.04, 31.91, 34.52,
100.54, 120.40, 140.00, 149.65; HRMS calcd for C10H16 136.1252,
found 136.1256.
1
afforded 189 mg (71%) of product: mp 153-154 °C; H NMR
δ 1.93-2.02 (m, 2 H), 2.09 (d, J ) 2.88 Hz, 1 H), 2.25 (d, J )
2.88 Hz, 1 H), 2.51 (m, 1 H), 2.64 (m, 1 H), 3.19 (d, J ) 17.43
Hz, 1 H), 3.40 (d, J ) 17.43 Hz, 1 H), 5.36 (s, 1 H), 7.45-7.66
(m, 4 H), 7.96 (m, 2 H), 8.19 (d, J ) 8.44 Hz); 13C NMR δ 21.78,
33.85, 34.03, 36.25, 40.49, 42.35, 46.26, 109.74, 111.05, 122.00,
124.99, 126.58, 126.91, 127.45, 128.46, 129.44, 130.88, 131.81,
132.51, 134.29, 134.64, 142.08. Anal. Calcd for C23H16N4: C,
79.29; H, 4.63; N, 16.08. Found: C, 78.85; H, 4.87; N, 15.70.
(E)-2-(2-Th ien ylm et h ylid en e)-1-m et h ylen ecyclop en -
ta n e (Table 1, entry 5): 1H NMR δ 1.82 (5 line pattern, J )
7.30 Hz, 2 H), 2.41-2.51 (m, 2 H), 2.69 (dt, J ) 7.24 Hz, 2.40
Hz, 2 H), 4.93 (apparent s, 1H), 5.39 (apparent s, 1 H), 6.91-
7.27 (m, 4 H); 13C NMR δ 24.20, 32.53, 34.13, 102.30, 113.23,
125.15, 126.77, 127.12, 130.90, 142.44, 150.45; HRMS for calcd
C11H12S 176.0660, found 176.0662.
(3a r,4â,8a r)-2-Met h yl-4-p r op yl-5,6,7,8,8a -h exa h yd r o-
3a H-2-a za -5-in d a cen e-1,3-d ion e (Table 2, entry 13).
A
solution of 84.1 mg (0.617 mmol) of (E)-2-butylidene-1-meth-
ylenecyclopentane and 61.0 mg (0.549 mmol) of N-methyl-
maleimide in 5 mL of toluene was heated at gentle reflux for
2 h. Removal of the solvent at reduced pressure and chroma-
tography of the residue over silica gel (hexanes; Rf ) 0.47) gave
96.3 mg (71%) of the isomerically pure product as a yellow
oil: 1H NMR δ 0.92 (t, J ) 7.00 Hz, 3 H), 1.39-1.43 (m, 3 H),
1.61-1.64 (m, 2 H), 1.76-1.86 (m, 2 H), 2.25-2.40 (m, 5 H),
2.52-2.60 (m, 2 H), 2.94 (s, 3 H), 3.09-3.11 (m, 1 H); 13C NMR
δ 14.18, 21.38, 22.47, 24.10, 24.54, 31.72, 34.29, 35.72, 36.48,
40.20, 43.91, 134.62, 139.25, 178.57, 180.26; HRMS calcd for
C15H21NO2 247.1572, found 247.1571.
4-P r op yl-2,3,4,7-tetr a h yd r o-1H-in d en e-5,6-d ica r boxy-
lic Acid Dim eth yl Ester (Table 2, entry 14). A solution of
104.2 mg (0.765 mmol) of (E)-2-butylidene-1-methylenecyclo-
pentane and 103.8 mg (0.730 mmol) of dimethyl acetylenedi-
carboxylate in 5 mL of toluene was heated at gentle reflux for
3 h. Removal of the solvent at reduced pressure and chroma-
tography of the residue over silica gel (5% EtOAc/hexanes; Rf
) 0.53) gave 142.8 mg (70%) of the product as an oil: 1H NMR
δ 0.82-0.98 (m, 3 H), 1.20-1.30 (m, 2 H), 1.47-1.61 (m, 2 H),
1.86-1.94 (m, 2 H), 2.10-2.40 (m, 4 H), 2.80-3.15 (m, 2 H),
3.32 (bs, 1 H), 3.76 (s, 3 H), 3.80 (s, 3 H); 13C NMR δ 14.27,
17.66, 22.07, 28.64, 33.14, 33.20, 35.14, 39.49, 52.02, 127.96,
130.92, 131.78, 133.56, 140.70, 167.77, 169.71; HRMS calcd
for C16H22O4 278.1518, found 278.1518.
(3a r,4â,8a r)-4-(Th iop h en -2-yl)-4,5,6,7,8,8a -h exa h yd r o-
3a H-2-oxa -5-in d a cen e-1,3-d ion e (Table 2, entry 10).
A
solution of 190.3 mg (1.08 mmol) of (E)-2-(2-thienylmeth-
ylidene)-1-methylenecyclopentane and 107.7 mg (1.10 mmol)
of maleic anhydride in 5 mL of toluene was heated at gentle
reflux for 2 h. Removal of the solvent at reduced pressure and
chromatography of the burgundy-colored residue over silica
gel using diethyl ether as eluent gave 173 mg (58%) of the
product as an oil: 1H NMR δ 1.87 (5 line pattern, J ) 7.81
Hz, 2 H), 2.28-2.46 (m, 5 H), 2.84 (d, J ) 16.86 Hz, 1 H), 3.41-
3.49 (m, 2 H), 4.18 (d, J ) 5.44 Hz, 1 H), 6.74 (d, J ) 3.41 Hz,
1 H), 6.89 (dd, J ) 5.12 Hz, J ) 3.41 Hz, 1 H), 7.12 (dd, J )
5.12 Hz, J ) 1.04 Hz, 1 H); 13C NMR δ 21.24, 21.76, 34.45,
35.61, 36.08, 37.73, 46.60, 125.44, 127.21, 127.64, 134.63,
135.58, 140.47, 171.26, 173.58; HRMS calcd for C15H14O3S
274.0664, found 274.0660.
(E)-2-(Cycloh exylm eth ylid en e)-1-m eth ylen ecyclop en -
ta n e (Table 1, entry 6): 1H NMR δ 0.85-0.92 (m, 4 H), 1.10-
1.40 (m, 6 H), 1.53 (t, J ) 7.11 Hz, 1 H), 2.05 (t of d, J ) 14.88,
J ) 8.09 Hz, 2 H), 2.14-2.26 (m, 2 H), 2.33-2.41 (m, 2 H),
4.74 (apparent s, 1 H), 5.19 (apparent s, 1 H), 5.81-5.85 (m,
1 H); 13C NMR δ 14.19, 22.76, 29.24, 29.60, 29.82, 31.92, 34.63,
100.62, 120.83, 139.89, 149.80; HRMS calcd for C13H20 176.1565,
found 176.1567.
(E)-2-Ben zylid en e-1-m eth ylen ecycloh exa n e (Table 1,
entry 9): 1H NMR δ 1.63 - 1.79 (m, 4 H), 2.41 (t, J ) 6.02 Hz,
2 H), 2.61 (t, J ) 6.13 Hz, 2 H), 4.79 (d, J ) 1.58 Hz, 1 H),
5.07 (d, J ) 1.58 Hz, 1 H), 6.64 (s, 1 H), 7.27-7.39 (m, 5 H);
13C NMR δ 26.33, 26.88, 29.62, 35.47, 108.75, 123.21, 126.36,
128.07, 129.43, 131.60, 142.86, 151.25; HRMS calcd for C14H16
184.1252, found 184.1249.
4-Cycloh exyl-2,3,4,7-t et r a h yd r o-1H -in d en e-5,6-d ica r -
boxylic Acid Dim eth yl Ester (Table 2, entry 11). A solution
of 116.1 mg (0.659 mmol) of (E)-2-(cyclohexylmethylidene)-1-
methylenecyclopentane and 69.0 mg (0.485 mmol) of dimethyl
acetylenedicarboxylate in 5 mL of toluene was heated at gentle
reflux for 3 h. Removal of the solvent at reduced pressure and
chromatography of the pale-yellow residue over silica gel (10%
(3ar,4â,9ar)-4-P h en yl-1,3-dioxo-3,a,4,5,6,7,8,9,9a-octah y-
d r on a p th o[2,3-c]fu r a n (Table 2, entry 15). A solution of
191.6 mg (1.04 mmol) of (E)-2-benzylidene-1-methylenecyclo-
hexane and 67.0 mg (0.683 mmol) of maleic anhydride in 5
mL of toluene was heated at gentle reflux for 1.5 h. Removal
of solvent at reduced pressure afforded a solid which was
recrystallized from heptane to give 164 mg (86%) of bone-white

8228 J . Org. Chem., Vol. 61, No. 23, 1996
Bailey et al.
crystals: mp 137-138 °C; 1H NMR δ 1.49-1.65 (m, 4 H), 1.86
(t, J ) 6.97 Hz, 2 H), 2.09 (t, J ) 5.63 Hz, 2 H), 2.38 (dd, J )
18.16 Hz, J ) 11.17 Hz, 1 H), 2.76 (d, J ) 18.16 Hz, 1 H), 3.35
(dd, J ) 11.17 Hz, J ) 3.08 Hz, 1 H), 3.44 (dd, J ) 9.37 Hz, J
) 7.16 Hz, 1 H), 3.63 (d, J ) 7.16 Hz, 1 H), 7.02-7.05 (m, 3
H), 7.23-7.25 (m, 2 H); 13C NMR δ 22.64, 22.93, 25.58, 29.43,
30.13, 37.23, 44.99, 45.32, 128.07, 128.22 (two carbons), 128.69,
129.09, 136.84, 171.60, 173.94. Anal. Calcd for C18H18O3: C,
76.57; H, 6.43. Found: C, 76.33; H, 6.09.
(E)- a n d (Z)-2-((Tr im eth ylsilyl)m eth ylid en e)-1-m eth -
ylen ecycloh exa n e (Table 1, entry 10): GC analysis indicated
that the product consisted of 70% of the bis-exocyclic diene as
a 2.5:1 mixture of the E- and Z-isomers along with 30% of the
known37 trimethyl(oct-7-en-1-yne)silane; 1H NMR [major
diastereoisomer] δ 0.10 (s, 9 H), 0.97-1.00 (m, 2 H), 1.67-
1.85 (m, 4 H), 2.20-2.38 (m, 2 H), 4.59 (apparent s, 1 H), 4.88
(apparent s, 1 H), 5.47 (apparent s, 1H); HRMS calcd for
C11H20Si 180.1334, found 180.1334.
(3a r,4r a n d 4â,9a r)-2-Meth yl-4-(tr im eth ylsilyl)-1,3-d i-
oxo-2,3,3a ,4,5,6,7,8,9,9a -d eca h yd r o-1H -b en z[f]isoin d ole
(Table 2, entry 16). A solution of 127.5 mg (0.707 mmol) of a
2.5:1 mixture of the E- and Z-isomers of 2-((trimethylsilyl)-
methylidene)-1-methylenecyclohexane and 94.7 mg (0.852
mmol) of N-methylmaleimide in 5 mL of toluene was heated
at gentle reflux for 2 h. Removal of the solvent at reduced
pressure gave a solid which was recrystallized from heptane
to afford 136.5 mg (66%) of bone-white crystals of the adduct
as a 4:1 ratio of diastereoisomers: mp 41-44 °C; 1H NMR
[major diastereoisomer] δ 0.03 (s, 9 H), 1.53 (m, 4 H), 1.87-
1.97 (m, 4 H), 2.14-2.23 (m, 2 H), 2.91 (s, 2 H), 2.95 (d, J )
Hz, 1 H), 3.15 (t, J ) Hz, 1 H); 13C NMR [mixture of
diastereoisomers] δ 0.82, 0.99, 22.98, 23.04, 23.16, 24.53, 28.12,
29.22, 29.62, 30.48, 31.00, 31.71, 31.84, 32.49, 40.19, 41.10,
41.15, 42.63, 125.86, 128.55, 130.75, 133.03, 179.77, 180.33,
180.87, 181.52. Anal. [mixture of diastereoisomers] Calcd for
C16H25NO2Si: C, 65.93; H, 8.65. Found: C, 66.19; H, 8.57.
1-(Tr im eth ylsilyl)-1,4,5,6,7,8-h exa h yd r on a p h th a len e-
2,3-d ica r boxylic Acid Dim eth yl Ester (Table 2, entry 17).
A solution of 130.0 mg (0.721 mmol) of a 2.5:1 mixture of the
E- and Z-isomers of 2-((trimethylsilyl)methylidene)-1-methyl-
enecyclohexane and 64.6 mg (0.455 mmol) of dimethyl acety-
lenedicarboxylate in 5 mL of toluene was heated at gentle
reflux for 3 h. Concentration of the product mixture gave an
oil which was purified by flash chromatography on silica gel
(10% EtOAc/hexanes; Rf ) 0.57) to afford 96.3 mg (68%) of
the product as a yellow oil: 1H NMR δ -0.13 (s, 9 H), 1.38-
1.46 (m, 4 H), 1.67-1.89 (m, 4 H), 2.47 (d, 1 H), 2. 64 (s, 1 H),
3.48-3.70 [overlapping patterns, i.e. 3.57 (s, 3 H), 3.47-3.63
(m, 1 H), 3.66 (s, 3 H)]; 13C NMR δ -0.94, 22.86, 23.01, 29.62,
30.35, 34.00, 39.34, 51.87, 53.31, 122.14, 128.60, 130.02,
138.26, 168.43, 168.71; HRMS calcd for C17H26O4Si 322.1600,
found 322.1598.
1.55-1.80 (m, 8 H), 1.83-1.94 (m, 2 H), 2.10-2.15 (m, 2 H),
2.21-2.31 (m, 2 H), 2.37-2.53 (m, 2 H), 2.65 (d, J ) 15.89 Hz,
1 H), 2.78-2.88 (m, 1H), 3.44-3.51 (m, 1 H), 4.33 (d, J ) 9.35
Hz, 1 H); 13C NMR δ 23.77, 24.87, 26.53, 28.25, 28.44, 32.46,
32.93, 36.30, 37.03, 41.91, 43.95, 116.86, 137.23, 139.73,
142.57, 171.93, 173.64. Anal. Calcd for C17H20O3: C, 74.96;
H, 7.41. Found: C, 74.56; H, 7.23.
4-Cycloh exylid en e-2,3,4,4a ,10a ,11-h exa h yd r o-1H -cy-
clop en ta [b]a n th r a cen e-5,10-d ion e (Table 2, entry 19). A
solution of 105.4 mg (0.605 mmol) of (E)-2-(cyclohexylidene-
methylidene)-1-methylenecyclopentane and 80.0 mg (0.506
mmol) of 1,4-naphthoquinone in 5 mL of toluene was heated
at gentle reflux for 2 h. Removal of the solvent at reduced
pressure gave a yellow solid which was recrystallized from
hexanes to afford 134.5 mg (80%) of bone-white crystals: mp
201 °C; 1H NMR δ 1.58 (t, J ) 3.58 Hz, 2 H), 1.68-1.79 (m, 6
H), 1.82-1.91 (m, 2 H), 2.10-2.41 (m, 5 H), 2.63 (dd, J ) 13.14
Hz, J ) 7.64 Hz, 2 H), 2.83-2.99 (m, 1 H), 3.37 (apparent
pentet, J ) 6.56 Hz, 1H), 4.39 (d, J ) 4.90 Hz, 1 H), 7.69-
7.73 (m, 2 H), 7.97-8.07 (m, 2 H); 13C NMR δ 23.31, 26.88,
28.83, 32.64, 32.71, 35.39, 37.19, 50.04, 51.41, 120.01, 126.67,
127.20, 133.26, 134.04, 134.24, 135.12, 136.98, 140.44, 195.99,
199.51. Anal. Calcd for C23H24O2: C, 83.10; H, 7.28. Found:
C, 82.84; H, 6.97.
(E)-2-[2-(3-Bu ten yl)ben zyliden e]-1-m eth ylen ecyclopen -
1
ta n e (18): H NMR δ 1.72 (apparent quintet, J ) 7.15 Hz, 2
H), 2.29-2.39 (m, 2 H), 2.51 (tt, J ) 7.25 Hz, J ) 2.31 Hz, 2
H), 2.59 (td, J ) 2.31, J ) 7.09 Hz, 2 H), 2.71-2.81 (m, 2 H),
4.94-5.10 (m, 3 H), 5.47 (apparent t, J ) 2.14 Hz, 1 H), 5.80-
5.97 (m, 1 H), 7.01 (br s, 1 H), 7.16-7.45 (m, 4 H); 13C NMR δ
24.53, 32.32, 33.69, 34.87, 102.44, 114.79, 117.34, 125.66,
126.72, 128.63, 128.81, 129.06, 132.12, 138.15, 140.23, 142.45,
150.32; HRMS calcd for C17H20 224.1565, found 224.1563.
(5a r,11br)-2,3,4,5,5a ,6,7,11b-Octa h yd r o-1H-cyclop en ta -
[c]p h en a n th r en e (19). A solution of 42.1 mg (0.187 mmol)
of (E)-2-[2-(3-butenyl)benzylidene]-1-methylenecyclopentane
(18) and 4.0 mg of BHT in 4 mL of deoxygenated benzene was
heated at 180 °C for 22 h in a screw-capped pressure tube.
The solvent was then removed, and the residue was purified
by flash chromatography on silica gel (hexanes; Rf ) 0.37) to
give 31.5 mg (75%) of the cycloadduct as an approximately 6:1
mixture of diastereoisomers: 1H NMR [major diastereoisomer]
δ 1.40-1.60 (m, 3 H), 1.80-1.92 (m, 4H), 2.02-2.15 (m, 2 H),
2.21-2.38 (m, 2 H), 2.42-2.60 (m, 1 H), 2.74-2.88 (m, 3 H),
3.08-3.17 (m, 1 H), 7.05-7.15 (m, 3 H), 7.30-7.38 (m, 1 H);
13C NMR [major diastereoisomer] δ 22.70, 26.67, 28.56, 29.24,
30.80, 35.96, 36.36, 40.25, 43.99, 125.18, 125.27, 125.92,
128.43, 135.01, 138.28, 138.68, 141.56; [minor diastereoisomer]
δ 21.44, 23.10, 24.58, 28.49, 29.34, 29.69, 33.07, 35.56, 41.11,
124.90, 125.60, 128.54, 130.31, 133.84, 134.97, 137.50, 138.99;
HRMS calcd for C17H20 224.1565, found 224.1564.
(E)-2-(Cycloh exylid en em et h ylid en e)-1-m et h ylen ecy-
clop en ta n e (Table 1, entry 11): 1H NMR δ 0.84-0.88 (m, 2
H), 1.51-1.59 (m, 6 H), 1.65 (pentet, J ) 7.22 Hz, 2 H), 2.08-
2.23 (m, 4 H), 2.35-2.45 (m, 2 H), 4.88 (apparent s, 1 H), 5.04
(apparent s, 1 H); 13C NMR δ 25.09, 26.25, 28.17, 31.67, 32.03,
33.95, 103.49, 103.80, 106.84, 148.60, 192.19; HRMS calcd for
C13H18 174.1409, found 174.1410.
4-C y c lo h e x y lid e n e -4,5,6,7,8,8a -h e x a h y d r o -3a H -5-
in d a cen e-1,3-d ion e (Table 2, entry 18). A solution of 115.5
mg (0.662 mmol) of (E)-2-(cyclohexylidenemethylidene)-1-
methylenecyclopentane and 64.7 mg (0.660 mmol) of maleic
anhydride in 5 mL of toluene was heated at gentle reflux for
2 h. Removal of the solvent at reduced pressure gave a yellow
solid which was recrystallized from benzene to afford 162.0
mg (90%) of bone-white crystals: mp 131-132 °C; 1H NMR δ
Ack n ow led gm en t. We are grateful to Drs. J on
Bordner and Frank Urban of Pfizer Central Research,
Groton, CT, for performing the X-ray analyses of 15 and
16. R.R.W. thanks Pfizer, Inc. for an Undergraduate
Research Fellowship. This work was supported by a
grant to W.F.B. and T.V.O. from the Connecticut
Department of Economic Development.
Su p p or tin g In for m a tion Ava ila ble: Copies of 1H or 13C
NMR spectra for all new compounds for which combustion
analytical data are not available (27 pages). This material is
contained in libraries on microfiche, immediately follows this
article in the microfilm version of the journal, can be ordered
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(37) Negishi, E.; Holmes, S. J .; Tour, J . M.; Miller, J . A.; Cederbaum,
F. E.; Swanson, D. R.; Takahashi, T. J . Am. Chem. Soc. 1989, 111,
3336.
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