[2 + 2] cycloreversion of [4.3.2]propella-1,3,11-trienes: An approach to cyclo[n]carbons from propellane-annelated dehydro[n]annulenes

Article abstract of DOI:10.1021/ja993314z

As a method to generate all-carbon molecules having highly reactive polyyne units from stable precursors, the [2 + 2] cycloreversion of [4.3.2]propella-1,3,11-triene derivatives was developed. To test the efficiency of this method, the reaction was first applied to simple diethynyl- and dibutadiynyl-substituted propellatrienes, which produced upon UV-irradiation linear hexatriyne and decapentayne derivatives, respectively. Next, dehydro[12]-, [16]-, [18]-, [20]-, and [24]annulene derivatives annelated by the [4.3.2]propellatriene units were prepared as precursors to the corresponding cyclo[n]carbons, a monocyclic form of carbon clusters. Laser-desorption mass spectra of the dehydroannulenes exhibited, in the negative mode, peaks due to the corresponding cyclo[n]carbon anions (n = 12, 16, 18, 20, and 24) formed by successive losses of aromatic indane fragments. Solution photolysis of the dehydro[16]annulene and dehydro[18] annulene derivatives formed reactive polyyne intermediates by [2 + 2] cycloreversion which were intercepted by furan to give the corresponding Diels-Alder adducts. The structures and spectroscopic properties of the dehydroannulenes annelated by the [4.3.2]propellatriene units, the precursors to cyclo[n]carbons, and those annelated by the oxanorbornadiene units, the products of the photolysis in furan, are discussed.

Full text of DOI:10.1021/ja993314z

1762
J. Am. Chem. Soc. 2000, 122, 1762-1775
[2 + 2] Cycloreversion of [4.3.2]Propella-1,3,11-trienes: An
Approach to Cyclo[n]carbons from Propellane-Annelated
Dehydro[n]annulenes
Yoshito Tobe,*,† Toshihiko Fujii,† Hideki Matsumoto,† Kunihiro Tsumuraya,†
Daisuke Noguchi,† Nobuko Nakagawa,† Motohiro Sonoda,† Koichiro Naemura,†
Yohji Achiba,‡ and Tomonari Wakabayashi§
Contribution from the Department of Chemistry, Faculty of Engineering, Osaka UniVersity,
Toyonaka, Osaka 560-8531, Japan, Department of Chemistry, Faculty of Science, Tokyo Metropolitan
UniVersity, Hachioji, Tokyo 193-0397, Japan, and DiVision of Chemistry, Graduate School of Science,
Kyoto UniVersity, Sakyo-ku, Kyoto 606-8502, Japan
ReceiVed September 13, 1999
Abstract: As a method to generate all-carbon molecules having highly reactive polyyne units from stable
precursors, the [2 + 2] cycloreversion of [4.3.2]propella-1,3,11-triene derivatives was developed. To test the
efficiency of this method, the reaction was first applied to simple diethynyl- and dibutadiynyl-substituted
propellatrienes, which produced upon UV-irradiation linear hexatriyne and decapentayne derivatives, respectively.
Next, dehydro[12]-, [16]-, [18]-, [20]-, and [24]annulene derivatives annelated by the [4.3.2]propellatriene
units were prepared as precursors to the corresponding cyclo[n]carbons, a monocyclic form of carbon clusters.
Laser-desorption mass spectra of the dehydroannulenes exhibited, in the negative mode, peaks due to the
corresponding cyclo[n]carbon anions (n ) 12, 16, 18, 20, and 24) formed by successive losses of aromatic
indane fragments. Solution photolysis of the dehydro[16]annulene and dehydro[18]annulene derivatives formed
reactive polyyne intermediates by [2 + 2] cycloreversion which were intercepted by furan to give the
corresponding Diels-Alder adducts. The structures and spectroscopic properties of the dehydroannulenes
annelated by the [4.3.2]propellatriene units, the precursors to cyclo[n]carbons, and those annelated by the
oxanorbornadiene units, the products of the photolysis in furan, are discussed.
Introduction
structures of carbon clusters are dependent on the number of
carbon atoms.6 The clusters smaller than C9 are linear, those
with the relatively narrow size regime of C10-C24 are believed
to exist in the form of monocyclic rings. With increasing number
of carbon atoms, bicyclic, tricyclic, and polycyclic structures
become more abundant. Three-dimensional cage structures
emerge from C30, which become dominant with clusters larger
than C60.
Among the various forms of carbon clusters, monocyclic
clusters, called cyclo[n]carbons, have been of exceptional
interest from many points of view, ranging from spectroscopy
and theoretical chemistry to synthetic organic chemistry, for
the following several reasons, owing to their unique structure
composed of two sets of cyclic arrays of p-orbitals, which are
perpendicular to each other.7 First, in the carbon cluster
chemistry, little has been done for the larger clusters having
monocyclic ring form, while extensive studies have been
undertaken for the spectroscopic determination of the structures
of linear carbon clusters with the carbon number smaller than
ten.1 Although the cyclic structure has been indicated by UPS4
There has been a long-standing interest in small carbon
clusters (Cn: n < 10) in the fields of spectroscopy and
theoretical chemistry in conjunction with the possible astro-
physical significance of these species.1 While extensive theoreti-
cal as well as spectroscopic studies have been carried out for
the carbon clusters smaller than C10, little was known for those
having larger carbon atoms. However, with the discovery of
the fullerene C60 as an unusually stable cluster2 and its
production in macroscopic quantities,3 increasing interest has
been focused on large carbon clusters in connection with the
mechanism of fullerene formation. On the basis of the ultraviolet
photoelectron spectroscopy4 of carbon cluster anions and the
mass chromatographic behavior5 of cations generated by laser
vaporization of graphite, it has been demonstrated that the
† Osaka University.
‡ Tokyo Metropolitan University.
§ Kyoto University.
(1) For reviews, see: (a) Weltner, W., Jr.; Van Zee, R. J. Chem. ReV.
1989, 89, 1713. (b) Maier, J. P. Chem. Soc. ReV. 1997, 21.
(2) Kroto, H. W.; Heath, J. R.; O’Brien, S. C.; Curl, R. F.; Smalley, R.
E. Nature 1985, 318, 162.
(3) Kra¨schmer, W.; Lamb, L. D.; Fostiropoulos, K.; Huffman, D. R.
Nature 1990, 347, 354.
(6) (a) von Helden, G.; Hsu, M.-T.; Kemper, P. R.; Bowers, M. T. J.
Chem. Phys. 1991, 95, 3835. (b) Hunter, J. M.; Fye, J. L.; Jarrold, M. F. J.
Chem. Phys. 1993, 99, 1785.
(4) (a) Yang, S. H.; Pettiette, C. L.; Conceicao, J.; Cheshnovsky, O.;
Smalley, R. E. Chem. Phys. Lett. 1987, 139, 233. (b)Yang, S.; Taylor, K.
J.; Craycraft, M. J.; Conceicao, J.; Pettiette, C. L.; Cheshnovsky, O.; Smalley,
R. E. Chem. Phys. Lett. 1988, 144, 431.
(5) (a) von Helden, G.; Hsu, M. T.; Gotts, N. G.; Kemper, P. R.; Bowers,
M. T. Chem. Phys. Lett. 1993, 204, 13. (b) Hunter, J.; Fye, J.; Jarrold, M.
F. J. Phys. Chem. 1993, 97, 3460.
(7) For reviews, see: (a) Diederich, F.; Rubin, Y. Angew. Chem., Int.
Ed. Engl. 1992, 31, 1101. (b) Diederich, F. Nature 1994, 369, 199. (c)
Diederich, F. In Modern Acetylene Chemistry; Stang, P. J., Diederich, F.,
Eds.; VCH: Weinheim, 1995; p 443. (d) Diederich, F.; Gobbi, L. Top.
Curr. Chem. 1999, 201, 43. (e) Tobe Y. In AdVances in Strained and
Interesting Organic Molecules; Halton, B., Ed.; JAI Press: Stamford, 1999,
in press.
10.1021/ja993314z CCC: $19.00 © 2000 American Chemical Society
Published on Web 02/12/2000

CycloreVersion of [4.3.2]Propella-1,3,11-trienes
J. Am. Chem. Soc., Vol. 122, No. 8, 2000 1763
and mass chromatographic investigations,5 detailed geometrical,
electronic, and vibrational information has not yet been obtained.
Second, it is becoming more and more likely that monocyclic
carbon clusters play a key role during the early stages of the
mechanism,8 although the mechanism of the fullerene formation
has not been clarified. Namely, ample experimental9 and
theoretical10 evidence has been accumulating which suggests
that carbon nucleation occurs through coalescence of medium-
sized carbon clusters, rather than sequential addition of small
pieces such as C2 and C3, which is followed by annealing to
form cage structures. Third, it is quite natural, from the
viewpoint of organic chemistry, to ask whether the Hu¨ckel rule
is valid for this class of novel π-systems composed of two sets
of cyclic arrays of p-orbitals, which are perpendicular to each
other.11 In this respect, a number of theoretical calculations have
been undertaken, but there still remains a controversy regarding
the most stable geometries of cyclo[n]carbons with 4n + 2π
electrons, particularly for cyclo[18]carbon.12 Finally, Sarre
reported recently, on the basis of the analysis of the ultrahigh-
resolution absorption spectra of diffuse interstellar bands at 6614
and 5797 Å and the molecular rotational contour calculations,
that large carbon ring molecules (i.e., cyclo[n]carbons) having
planar oblate symmetric structures are good candidates for the
carriers of these bands.13
It is, therefore, extremely important to synthesize and
determine the molecular structures of cyclo[n]carbons by
spectroscopic methods. In this context, a number of investiga-
tions have been undertaken to synthesize cyclo[n]carbons from
organic precursors having dehydroannulene frameworks. A
pioneering project to synthesize cyclo[n]carbons from organic
precursors having the desired macrocyclic carbon framework
was initiated by the Diederich’s group more than a decade ago.
The first precursor was dodecadehydro[18]annulene 1 fused by
three dibenzobicyclo[2.2.2]octatriene units, from which elimina-
tion of three molecules of anthracene in a retro-Diels-Alder
sense would generate cyclo[18]carbon.14 The formation of C18
was indeed observed in the laser-desorption time-of-flight (LD-
TOF) mass spectra of 1. However, attempts to prepare macro-
scopic quantities of C18 by flash vacuum pyrolysis did not give
C18, and only anthracene and polymeric material were obtained.
The second type of precursor is represented by the stable
dinuclear cobalt complexes 2 and 3, which can be regarded as
transition metal complexes of C18 and C24, respectively.14b,15
Attempted decomplexation of 2 and 3 to give the corresponding
cyclocarbons was unsuccessful. The third type of molecule is
exemplified by dehydroannulenes 4, 5, and 6 annelated with
cyclobutenedione units, which would produce C18, C24, and C30,
respectively, by multistep decarbonylation.9d,14b,16 The formation
of C18, C24, and C30 ions was observed both in the positive and
negative modes of the LD Fourier transform (FT) mass spectra
of the respective precursors 4-6 together with the intermediate
ions formed by the successive losses of carbon monoxide. It
should be pointed out that, depending on the desorption
+
conditions, C70 was formed by the gas-phase ion molecule
reaction of C18 and C24 (tetramerization or trimerization followed
by loss of C2) from 4 and 5, respectively. More interestingly,
C60+, which proved to possess the fullerene structure, was
formed predominantly by coalescence (dimerization) between
C30+ and C30 derived from the precursor 6. A notable advantage
of these carbon oxides is the fact that decarbonylation can, in
principle, be carried out photochemically in rigid matrices at
low temperatures to detect highly reactive cyclocarbons by
spectroscopic methods. Indeed, irradiation of 4 isolated in a low-
temperature matrix resulted in the formation of ketene inter-
mediates which were characterized by the IR absorption at 2115
cm-1 14b
While subsequent loss of carbon monoxide took place
.
as judged from the appearance of the absorption of CO at 2138
cm-1, definite spectroscopic evidence for the formation of cyclo-
[18]carbon has not been obtained. Rees planned to use the
oxidative degradation of the 1-amino-1,2,3-triazole group to
produce the triple bonds of cyclocarbons and prepared N-
benzylidene-protected aminotriazole derivatives 7-9 as precur-
sors to cyclocarbons C18, C24, and C30.17 However, attempts to
remove the benzylidene protective group from 7 were not
successful.
(8) For reviews, (a) Schwarz, H. Angew. Chem., Int. Ed. Engl. 1993,
32, 1412. (b) Goroff, N. S. Acc. Chem. Res. 1996, 29, 77.
(9) (a) Hunter, J.; Fye, J.; Jarrold, M. F. Science 1993, 260, 784. (b)
von Helden, G.; Gotts, N. G.; Bowers, M. T. Nature 1993, 363, 60. (c) von
Helden, G.; Gotts, N. G.; Bowers, M. T. J. Am. Chem. Soc. 1993, 113,
4363. (d) McElvany, S. W.; Ross, M. M.; Goroff, N. S.; Diederich, F.
Science 1993, 259, 1394. (e) Hunter, J. M.; Fye, J. L.; Roskamp, E. J.;
Jarrold, M. F. J. Phys. Chem. 1994, 98, 1810.
(10) Strout, D. L.; Scuseria, G. E. J. Chem. Phys. 1996, 100, 6492.
(11) Hoffmann, R. Tetrahedron 1966, 22, 521.
(12) For a review, see: Plattner, D. A.; Li, Y.; Houk, K. N. In Modern
Acetylene Chemistry; Stang, P. J., Diederich, F., Eds.; VCH: Weinheim,
1995; p 1.
(13) Kerr, T. H.; Hibbins, R. E.; Miles, J. R.; Fossey, S. J.; Somerville,
W. B.; Sarre, P. J. Mon. Not. R. Astron. Soc. 1996, 283, L105.
(14) (a) Diederich, F.; Rubin, Y.; Knobler, C. B.; Whetten, R. L.;
Schriver, K.; Houk, K. N.; Li, Y. Science 1989, 245, 1088. (b) Diederich,
F.; Rubin; Y.; Chapman, O. L.; Goroff, N. S. HelV. Chim. Acta 1994, 77,
1441.
We planned to utilize the fragmentation of [4.3.2]propella-
1,3,11-triene derivatives in a retro [2 + 2] sense ([2 + 2]
cycloreversion) to generate highly reactive carbon-carbon triple
bonds such as those involved in cyclo[n]carbons from appropri-
ate precursors as shown in Scheme 1. The [2 + 2] cycloreversion
of cyclobutane derivatives to generate a carbon-carbon double
bond has been frequently utilized with success to produce highly
unstable molecules such as cyclobutadiene.18 The corresponding
reaction of a cyclobutene derivative would form a carbon-
carbon triple bond, but in this case electrocyclic ring-opening
leading to a buta-1,3-diene would take place in competition with
(16) (a) Rubin, Y.; Knobler, C. B.; Diederich, F. J. Am. Chem. Soc. 1990,
112, 1607. (b) Rubin, Y.; Kahr, M.; Knobler, C. B.; Diederich, F.; Wilkins,
C. L. J. Am. Chem. Soc. 1991, 113, 495.
(15) Rubin, Y.; Knobler, C. B.; Diederich, F. J. Am. Chem. Soc. 1990,
112, 4966.
(17) Adamson, G. A.; Rees, C. W. J. Chem. Soc., Perkin Trans. 1 1996,
1335.

1764 J. Am. Chem. Soc., Vol. 122, No. 8, 2000
Tobe et al.
Scheme 1
Scheme 2a
the desired cycloreversion.19 This undesired reaction pathway
can be suppressed by geometrical constraints. Namely, Paquette
reported, as part of his extensive investigations in propellane
chemistry, that photolysis of [4.4.2]propellapentaene 10a and
the corresponding triene 10b takes place smoothly, leading to
the formation of naphthalene and tetrahydronaphthalene, re-
spectively, together with ethyne (not detected).20 On the basis
of our knowledge that [4.3.2]propellane derivatives can be
readily prepared by means of [2 + 2] photocycloaddition of
bicyclo[4.3.0]non-1(6)-en-2-one (11) to alkenes and alkynes,21
we chose the [4.3.2]propellatriene system as the key structural
element as shown in Scheme 1. Accordingly, we designed
dehydro[12]-, [16]-, [18]-, [20]-, and [24]annulene derivatives
12-16 annelated by [4.3.2]propellatriene units as the precursors
to the cyclo[n]carbons where n ) 12, 16, 20, 18, and 24,
respectively. In view of the presence of diastereomers in 12-
16, it was more desirable to prepare symmetric precursors
composed of [4.4.2]propellapentaene unit like 10a. However,
we anticipated that the preparation of a building block such as
diethynyl[4.3.2]propellatriene 17c would be much easier than
that of the corresponding [4.4.2] congener.20
a (a) For 19a: 1,4-bis(methoxymethoxy)-2-butyne, hν; for 19b: 1,4-
diacetoxy-2-butyne, hν. (b) for 20a: i, TMSOTf, Et3N; ii, Pd(OAc)2;
for 20b: i, 5,5-dibromo-2,2-dimethyl-1,3-dioxane-4,6-dione; ii, LiCl,
Li2CO3. (c) i, NaBH4, CeCl3‚7H2O; ii, (2,4-dinitrophenyl)sulfenyl
chloride. (d) for 21a: HCl; for 21b: NaOH. (e) MnO2. (f) diethyl
trichloromethylphosphonate, BuLi, -100 °C. (g) BuLi, TMSCl (for
17a) or TBDMSCl (for 17b). (h) Bu4NF or LiOH‚H2O. (i) BrCtCTIPS,
CuCl, NH4OH‚HCl, aqueous EtNH2.
photoelectron spectra have been reported elsewhere.23 In addi-
tion, the structures and spectroscopic properties of the dehy-
droannulenes annelated by the [4.3.2]propellatriene units and/
or oxanorbornadiene units are discussed.
Results and Discussion
Model Study for [2 + 2] Cycloreversion. Although the
cycloreversion takes place exclusively in the simple systems
10a and 10b, it is expected that skeletal isomerization, well-
known as di-π-methane rearrangement,24 would take place in
competition with the [2 + 2] cycloreversion, particularly when
the desired pathway is hindered by strain. Accordingly, to test
whether the cycloreversion pathway predominates in extensively
conjugated π systems, we started with the model systems which
would produce linear polyynes before investigating the carbon
ring synthesis. Toward this end, diethynylpropellatrienes 17a-
17c were prepared according to the synthetic pathways shown
in Scheme 2. Namely, photocycloaddition of enone 1125 with
In this paper, we report the model study of the photochemical
[2 + 2] fragmentation of simple 11,12-dialkynylated [4.3.2]-
propellatriene derivatives 17a, 17b, and 18, the synthesis and
spectral properties of dehydro[12]-, [16]-, [18]-, [20]-, and [24]-
annulene derivatives 12-16 annelated by [4.3.2]propellatriene
units, and their fragmentation in the laser-desorption mass
spectra and by ultraviolet irradiation.22 The spectroscopic
characterization and structural assignment of thus produced
cyclo[n]carbon anions (n ) 12, 16, 18, 20, 24) by ultraviolet
(18) (a) Masamune, S.; Suda, M.; Ona, H.; Leichter, L. M. J. Chem.
Soc., Chem. Commun. 1972, 1269. (b) Maier, G.; Hoppe, B. Tetrahedron
Lett. 1973, 861. (c) Maier, G.; Reisenauer, H. P. Tetrahedron Lett. 1976,
3591.
(19) For a review, Leigh, W. J. Chem. ReV. 1993, 93, 487.
(20) Paquette, L. A.; Wingard, R. E., Jr.; Photis, J. M. J. Am. Chem.
Soc. 1974, 96, 5801.
(21) (a) Peet, N. P.; Cargill, R. L.; Bushey, D. F. J. Org. Chem. 1973,
38, 1218. (b) Tobe, Y.; Hoshino, T.; Kawakami, Y.; Sakai, Y.; Kimura,
K.; Odaira, Y. J. Org. Chem. 1978, 43, 4334. (c) Kakiuchi, K.; Tsugaru,
T.; Takeda, M.; Wakaki, I.; Tobe, Y.; Odaira, Y. J. Org. Chem. 1985, 50,
488.
(22) For preliminary reports, see: (a) Tobe, Y.; Fujii, T.; Naemura, K.
J. Org. Chem. 1994, 59, 1236. (b) Tobe, Y.; Fujii, T.; Matsumoto, H.;
Naemura, K.; Achiba, Y.; Wakabayashi, T. J. Am. Chem. Soc. 1996, 118,
2758. (c) Tobe, Y.; Matsumoto, H.; Naemura, K.; Achiba, Y.; Wakabayashi,
T. Angew. Chem., Int. Ed. Engl. 1996, 35, 1800.
(23) Wakabayashi, T.; Kohno, M.; Achiba, Y.; Shiromaru, H.; Momose,
T.; Shida, T.; Naemura, K.; Tobe, Y. J. Chem. Phys. 1997, 107, 4783.
(24) For a review, see: Zimmerman, H. E. In Rearrangements in Ground
and Excited States; de Mayo, P., Ed.; Academic Press: New York, 1980;
Vol. 3, p 131.
(25) Conley, R. T.; Nowark, B. E. J. Org. Chem. 1961, 26, 692.

CycloreVersion of [4.3.2]Propella-1,3,11-trienes
J. Am. Chem. Soc., Vol. 122, No. 8, 2000 1765
1,4-bis(methoxymethoxy)-2-butyne26 gave cycloadduct 19a
which was oxidized to dienone 20a through the silyl enol ether27
and then transformed into propellatriene 21a using the protocol
of Reich et al.28 Deprotection of the MOM group afforded diol
21c which was oxidized by MnO2 to give dialdehyde 22. The
formyl group was converted to the ethynyl group using the
Normant protocol29 through bis(dichloromethylene) compound
23, giving diethynylpropellanes 17a and 17b. In the case of
the preparation of 17b, the trapping of the dianion, formed by
elimination of HCl followed by chlorine-lithium exchange from
23, with chloro-tert-butyldimethylsilane was carried out at 0
°C because of the low reactivity of the chlorosilane with the
anion. As a result, we obtained bisallene 24 besides the desired
product 17b, which was formed presumably by nucleophilic
attack of the excess butyllithium to an intermediate of the
reaction.30 Removal of the silyl-protecting groups of 17a and
17b yielded the unstable parent hydrocarbon 17c. Alternatively,
diol 21c was prepared by the similar sequence of reactions by
photocycloaddition of enone 11 with 1,4-diacetoxy-2-butyne (to
give 19b), bromination-dehydrobromination (to give 20b), 1,2-
reduction-1,4-dehydration (to give 21b), and hydrolysis. The
overall efficiencies of both procedures are almost identical. Bis-
(butadiynyl)propellatriene 18 was prepared by the Cadiot-
Chodkiewicz coupling31 of 17c with 1-bromo-2-(triisopropylsilyl)-
ethyne.32
Scheme 3a
a (a) i, trichloroethylene, hν; ii, t-BuOK. (b) i, 5,5-dibromo-2,2-
dimethyl-1,3-dioxane-4,6-dione; ii, LiCl, Li2CO3. (c) i, NaBH4,
CeCl3‚7H2O; ii, (2,4-dinitrophenyl)sulfenyl chloride. (d) HCtCTMS
(for 17a) or HCtCTIPS (for 17d), Pd(PPh3)4, CuI, Et3N.
Scheme 4
We developed another more efficient method for the prepara-
tion of diethynyl propellatrienes based on the Sonogashira
coupling reaction33 of dichloropropellatriene 27 with appropriate
alkynes (Scheme 3). Thus, photoaddition of enone 11 with
trichloroethene and subsequent elimination of HCl gave dichlo-
roketone 25. Bromination-dehydrobromination of 25 to dienone
26 followed by a 1,2-reduction-1,4-dehydration sequence yielded
triene 27. Reaction of 27 with appropriate trialkylsilyl-protected
alkynes using Pd(0) and Cu(I) catalysts afforded 17a and 17d
in good yields.
Irradiation of a hexane solution of 17a with a low-pressure
mercury lamp resulted in the formation of hexatriyne 28a32,34
in 66% isolated yield together with indane (Scheme 4). As
byproducts, a small amount (14%) of a 1:1 mixture of
isomerization products 29a and 30a was obtained. Although
29a and 30a could not be separated, their structures were
(26) Hraft, M. E.; Pankowski, J. Synlett 1994, 865.
(27) Ito, Y.; Hirao, T.; Saegusa, T. J. Org. Chem. 1978, 43, 1011.
(28) Reich, H. J.; Wollowitz, S. J. Am. Chem. Soc. 1982, 104, 7051.
(29) Villiears, J.; Perriot, P.; Normant, J. F. Synthesis 1975, 458.
(30) Although the mechanism of the formation of 24 is not certain, the
possibility that it was produced by the nucleophilic attack of the organo-
lithium reagent to the once formed 17b was excluded, since diyne 17b was
inert to butyllithium under the reaction conditions.
(31) (a) Chodkiewicz, W.; Cadiot, P. Compt. Rend. 1955, 241, 1055.
(b) Brandsma, L. PreparatiVe Acetylenic Chemistry, 2nd ed.; Elsevier:
Amsterdam, 1988; p 213.
(32) Rubin, Y.; Lin, S. S.; Knobler, C. B.; Anthony, J.; Boldi, A. M.;
Diederich, F. J. Am. Chem. Soc. 1991, 113, 6943.
(33) For a review, see: Sonogashira, K. In ComprehensiVe Organic
Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford, 1991; Vol.
3, p 521.
assigned on the basis of the NMR spectra. The salient feature
of the 1H NMR spectra of 29a involves two methine signals at
δ 3.34 and 2.69 ppm which couple with the vinyl protons at δ
5.90 and 5.58, respectively. The cyclooctatetraene structure of
30a was elucidated on the basis of the presence of four vinyl
proton signals in the 1H NMR and eight sp2 carbon signals (four
quaternary and four tertiary carbons) in the 13C NMR spectra.
The compound 29a can be envisioned as a product of vinylogous
di-π-methane rearrangement of 17a. Whether 30a is a direct
photochemical product or an isomerization product of 29a by
trace acid was not confirmed. Similarly, irradiation of tert-
butyldimethylsilyl derivative 17b gave hexatriyne 28b32 (67%)
together with a mixture of 29b and 30b (6%). Photolysis of
(34) (a) Alberts, A. H. Recl. TraV. Chim. Pays-Bas 1989, 108, 242. (b)
Fritch, J. R.; Vollhardt, K. P. C. Organometallics 1982, 1, 590.

1766 J. Am. Chem. Soc., Vol. 122, No. 8, 2000
Tobe et al.
Scheme 5. (a) Cu(OAc)2, Pyridine or Cu(OAc)2, CuCl,
Pyridine
symmetry are drawn in the Scheme. The presence of dodeca-
dehydro[18]- and hexadecadehydro[24]annulene cores in 15 and
16, respectively, was confirmed by comparison of the 1H NMR
and electronic spectra with those of related compounds.14-16,38,39
Next, we synthesized the precursors of cyclo[12]-, [16]-, and
[20]carbons, dehydro[12]-, [16]-, and [20]annulene systems 12-
14 which correspond to the trimer, tetramer, and pentamer of
chloroethynylpropellatriene 33b. Monoethynylation of dichlo-
ropropellane 27 with 2-methyl-3-butyn-2-ol to furnish 33a was
accomplished in 60-70% yields by Pd(0)-Cu(I)-catalyzed
coupling. The product was readily separated from the dieth-
ynylation product 17e by chromatography. Removal of the
terminal carbinol moiety gave alkyne 33b. However, all attempts
for cyclization of 33b by Pd(0)-Cu(I)-catalyzed coupling under
a variety of conditions failed to afford the desired cyclization
products. Dimer 34, formed by the oxidative coupling of the
terminal alkyne moiety of 33b, was obtained as an exclusive
product. On the other hand, we were gratified to find that, when
33a was subjected to the phase-transfer conditions40 under which
deprotection and coupling took place in one pot, the dehydroan-
nulenes 12 (dark red), 13 (dark violet), and 14 (reddish orange)
were obtained in 1, 11, and 1% yields, respectively (Scheme
6). These products were readily separated by chromatography,
but individual compounds are also inseparable mixtures of
diastereomers (only those with highest symmetry drawn in the
scheme). The fact that the tetramer 13 was obtained in higher
yield than the trimer 12 is explained in terms of the geometrical
deformation which is smaller in the former than in the latter as
described below. Trimer 12 was also prepared selectively in a
stepwise manner by three successive Pd(0)-Cu(I)-catalyzed
coupling reactions as shown in Scheme 7. Namely, the reaction
of diethynylpropellane 17c with an excess of 27 yielded the
1:2 coupling product 35 (50%), which was coupled with
2-methyl-3-butyn-2-ol to give monoethynylated compound 36
(47%) and disubstituted product 37 (36%). Finally, intramo-
lecular cyclization of 36 under the phase-transfer conditions
provided 12 in 16% yield.
dibutadiynylpropellatriene 18 under similar conditions afforded
decapentayne 3132 in 74% isolated yield. No isomerization
product of the starting material was detected in this case. Thus,
it was revealed that the desired [2 + 2] cycloreversion takes
place predominantly in the model system even for the propel-
latrienes with extended conjugation, leading to the formation
of linear polyynes.
We also examined the photolysis of bisallene 24 to generate
a hexapentaene derivative 32.35 Thus, irradiation of 24 with a
low-pressure mercury lamp in THF-d8 at 0 °C resulted in the
formation of an unstable product, together with indane, which
was assigned to be 32 on the basis of the spectral properties
characteristic to a cumulene; 13C NMR δ 189.9, 174.9, 156.8,
154.1 ppm; IR 2060, 2040, 2000, 1960, 1880, 1820 cm-1; UV-
vis λmax (cyclohexane) 584 and 527 nm. An attempt to isolate
the product 32 was unsuccessful because of its rapid decom-
position to form tarry brown materials.
Generation of Cyclo[n]carbons by [2 + 2] Cycloreversion
of Propellane-Annelated Dehydroannulenes. With the cyclo-
carbon precursors 12-16 in hand, we investigated the generation
of the corresponding cyclo[n]carbons by [2 + 2] cycloreversion.
First, in the laser-desorption time-of-flight (LD TOF) mass
spectra, we observed the formation of cyclo[n]carbons (n ) 12,
16, 18, 20, 24) from the corresponding dehydroannulene
derivatives 12-16 as shown in Figures 1 and 2. As shown in
the inset of Figure 1, the positive mode of LD-TOF mass
spectrum of 15 exhibited only the peak due to the indane
fragment. Likewise, the peak due to indane was exclusively
observed in the positive mode spectra of 12-14 and 16. On
the other hand, in the negative mode spectrum of 15 (Figure
1), we observed the peaks due to the parent ion (C18R3- where
R denotes the indane fragment) and the anions resulting from
Synthesis of Dehydroannulenes Annelated by [4.3.2]-
Propellatriene Units. With the above results on the model study
for the linear polyyne synthesis in hand, we investigated the
cyclo[n]carbon synthesis using the [2 + 2] cycloreversion of
[4.3.2]propellatriene derivatives. We started with the synthesis
of precursors of cyclo[18]- and [24]carbons, dehydro[18]-
annulene 15 and dehydro[24]annulene 16 which correspond to
the trimer and tetramer of diethynylpropellatriene 17c, respec-
tively. Thus, copper(II)-mediated oxidative coupling of 17c
under Eglinton’s conditions36 gave the yellowish orange trimer
15 as the major product together with a small amount of carmine
red tetramer 16 in total yield of 39% (Scheme 5). In an other
run under modified conditions using copper(I) and copper(II)
salts,37 a nearly 1:1 mixture of 15 and 16 was obtained (56%
yield). Both 15 and 16 were obtained as mixtures of diastere-
omers which were not separated and only those with highest
(38) (a) Okamura, W. H.; Sondheimer, F. J. Am. Chem. Soc. 1967, 89,
5991. (b) McQuilkin, R. M.; Garratt, P. J.; Sondheimer, F. J. Am. Chem.
Soc. 1970, 92, 6682. (c) Anthony, J.; Knobler, C. B.; Diederich, F. Angew.
Chem., Int. Ed. Engl. 1993, 32, 406. (d) Zhou, Q.; Carrol, P. J.; Swager, T.
M. J. Org. Chem. 1994, 59, 1294. (e) Guo, L.; Bradshaw, J. D.; Tessier, C.
A.; Youngs, W. J. J. Chem. Soc., Chem. Commun. 1994, 243. (f) Haley,
M. M.; Brand, S. C.; Pak, J. J. Angew. Chem., Int. Ed. Engl. 1997, 36, 836.
(g) Nishinaga, T.; Kawamura, T.; Komatsu, K. J. Org. Chem. 1997, 62,
5354. (h) Pak, J. J.; Weakley, T. J. R.; Haley, M. M. J. Am. Chem. Soc.
1999, 121, 8182.
(39) For recent reviews, see: (a) Haley, M. M. Synlett 1998, 557. (b)
Haley, M. M.; Pak, J. J.; Brand, S. C. Top. Curr. Chem. 1999, 201, 82.
(40) (a) Rossi, A.; Carpita, A.; Quirici, M. G.; Gaudenzi, M. L.
Tertrahedron 1982, 38, 631. (b) Huyne, C.; Linstrumelle, G. Tertrahedron
1988, 44, 6337.
(35) For tetra-tert-butylhexapentaene, see: (a) Hartzler, H. D. J. Am.
Chem. Soc. 1971, 93, 4527. (b) Negi, T.; Kaneda, T.; Mizuno, H.; Toyota,
T.; Sakata, Y.; Misumi, S. Bull. Chem. Soc. Jpn. 1974, 47, 2398.
(36) Behr, O. M.; Eglinton, G.; Galbraith, A. R.; Raphael, R. A. J. Chem.
Soc. 1960, 3614.
(37) (a) O’Krongly, D.; Denmeade, S. R.; Chiang, M. Y.; Breslow, R.
J. Am. Chem. Soc. 1985, 107, 5544. (b) Scott, L. T.; Cooney, M. J.; Otte,
C.; Puls, C.; Haumann, T.; Boese, R.; Carrol, P. J.; Smith, A. B., III; de
Meijere, A. J. Am. Chem. Soc. 1994, 116, 10275.

CycloreVersion of [4.3.2]Propella-1,3,11-trienes
J. Am. Chem. Soc., Vol. 122, No. 8, 2000 1767
Scheme 6a
Figure 1. Negative and positive (inset) modes LD-TOF mass spectra
of cyclo[18]carbon precursor 15. R denotes the indane fragment.
and C30-) from the corresponding precursor molecules was
reported previously,9d,14,16 the formation of cyclo[n]carbon
-
anions with n ) 4m carbon atoms (C12-, C16-, and C20
)
represents the first examples. The structures of the carbon cluster
anions (C12-, C16-, C18-, C20-, and C24-) generated from the
dehydroannulene derivatives 12-16 were investigated on the
basis of the ultraviolet photoelectron spectra of the anions
obtained by subjecting the mass selected anions to a second
laser pulse (266 nm), which were compared with those of the
anions of the same carbon numbers obtained by laser vaporiza-
tion of graphite.23 On the basis of the splitting frequencies due
to vibrational excitation of the neutral cyclocarbons produced
by detaching an electron from the corresponding anions, it was
deduced that cyclo[n]carbons with 4m carbon atoms, that is,
C16, C20, and C24, should possess a polyyne structure with
alternating single and triple bonds. Namely, the vibrational
frequencies observed at 1775, 1930, and 1935 cm-1 were
assigned to the tangential motion of the C-C bond in C16 of
C8h, C20 of C10h, and C24 of C12h symmetry, respectively. On
the other hand, cyclo[18]carbon bearing 4m + 2 carbon atoms
must be cumulenic, since its vibrational frequency at 645 cm-1
can be assigned to the totally symmetric C-C stretching
(breathing) mode of C18 of D9h symmetry. In the case of the
smallest member C12, it is not clear whether it is a polyyne or
a cumulene because of the relatively low signal vs noise ratio
of the spectra probably due to its decomposition to the linear
isomer.23
(a) 2-methyl-3-butyn-2-ol, Pd(PPh3)4, CuI, BuNH2. (b) KOH. (c)
Pd(PPh3)4, CuI, BuNH2. (d) Pd(PPh3)4, CuI, aq. NaOH, benzyltriethyl-
ammonium chloride.
Scheme 7a
To examine the possible formation of cyclo[n]carbons by
photochemical [2 + 2] cycloreversion, a solution of 15 in THF-
d8 was irradiated with a low-pressure mercury lamp at 0 °C,
yielding indane along with uncharacterized polymeric materials.
Apparently, the intermediates formed by elimination of indane
fragment(s) are too reactive at this temperature. To intercept
reactive intermediates formed during the photolysis, irradiation
was then carried out using furan as a solvent, giving three
oxanorbornadiene-annelated products 38-40 in 15, 27, and 11%
isolated yields, in which one, two, or all indane units are
replaced by the furan moieties, respectively (Scheme 8). The
structures of the products 38-40, especially the regiochemistry
(a) 27 (excess), Pd(PPh3)4, CuI, Et3N. (b) 2-methyl-3-butyn-2-ol,
PdCl2(PhCN)2, CuI, piperidine. (c) Pd(PPh3)4, CuI, aq. NaOH, ben-
zyltriethylammonium chloride.
the successive losses of one, two, and three indane fragments
(C18R2-, C18R-, and C18-, respectively). Also observed are the
-
anions, C36 and C54-, corresponding to the dimer and trimer
of C18-, respectively. However, we have no information
regarding the structure of these high molecular weight clusters
at this moment.41 The LD-TOF mass spectra of 12-14 and 16
exhibit essentially the same pattern of peaks as that of 15 as
(41) The photoelectron spectrum of C32- revealed that its structure was
different from that of the carbon cluster generated from graphite by the
laser vaporization; see ref 23.
shown in Figure 2. Although the size-selective generation of
-
cyclo[n]carbon anions with n ) 6m carbon atoms (C18-, C24
,

1768 J. Am. Chem. Soc., Vol. 122, No. 8, 2000
Tobe et al.
Figure 3. AM1-calculated geometries of model compound 47 formed
during photolysis of dehydro[18]annulene 15. Bond lengths are in Å
and bond angles in degrees.
Scheme 8
calculations for the tetradecadehydro[18]annulene 41 (Figure
3), as a model compound for the reactive intermediate formed
from 15 by elimination of one of the indane units. As shown in
Figure 3, the calculated bond angle of the central triple bond
of the decapentayne moiety of 41 is most severely deformed
from linearity. In addition, [4 + 2] addition of furan to other
position of the polyyne chain of 41 would lead to a structure
which is apparently more strained than that actually formed.
We expected that the retro [4 + 2] fragmentation of the
oxanorbornadiene unit in 40 would provide an alternative route
to cyclocarbon chemistry. However, although such fragmenta-
tion was indeed observed in the LD-TOF mass spectrum of 40
as shown in Figure 4, it also exhibited fragmentation due to
the loss of CO (or CHO) and C2H2 or (C2H3) units, leading to
a complex spectrum pattern.
The photolysis of dehydro[16]annulene 13, which was
obtained most readily within the series of the compounds 12-
14, was also carried out in furan. In this case, the reaction was
sluggish compared to the similar reaction of 15, and only
monosubstitution product 42 was isolated in 31% yield (30%
of 13 recovered) (Scheme 9). Further irradiation led to the
extensive formation of complex mixture of products and
polymeric materials.
Figure 2. Negative mode LD-TOF mass spectra of cyclo[12]-, [16]-,
[20]-, and [24]carbon precursors 12 (a), 13 (b), 14 (c), and 16 (d). R
denotes the indane fragment.
of the [4 + 2] cycloaddition of furan, were established by the
13C NMR chemical shifts of their sp carbons. Namely, 38 and
39 exhibit only five clusters of the sp carbon signals (38: δ
95.3, 86.3, 84.0, 83.5, 82.0, 81.8 ppm, 39: δ 96.1, 95.7, 87.6,
84.5, 82.9 ppm) and 40 (δ 97.0, 89.3 ppm) does only two,
indicating that these compounds have an approximate C3
symmetry. Monitoring the photochemical reaction of 15 in furan
by HPLC suggests that 38 is formed initially, then it is converted
to 39, which finally gives 40. Consequently, though these results
do not imply the direct formation of cyclo[18]carbon by the
photolysis of 15, they clearly show that the elimination of at
least one of the indane units takes place efficiently by [2 + 2]
cycloreversion from 15 (and 38 and 39 as well) to produce
highly reactive dehydro[18]annulene intermediates.
It should be noted that the [4 + 2] cycloaddition of furan
takes place regioselectively giving the products 38-40, in which
the furan units are located at the same position as those occupied
by the propellane units before they were extruded. To get insight
into this regioselectivity, we undertook semiempirical AM1
These results on the solution photolyses of 13 and 15 seem
promissing in view of the photochemical generation of cyclo-
[n]carbons by UV irradiation in low-temperature matrices.
However, the limited solubility, particularly in the case of

CycloreVersion of [4.3.2]Propella-1,3,11-trienes
J. Am. Chem. Soc., Vol. 122, No. 8, 2000 1769
formation, and HOMO-LUMO gaps of 43-48 are summarized
in Table 1. In the cyclobutene-fused trimer 43, the angle θ
between the two C(sp2)-C(sp) bonds flanking the cyclobutene
ring ( ∼80°) is substantially reduced from the normal angle (
∼90°) of the diethynylcyclobutene system. Similarly, the triple
bond is considerably deformed (â ) 170.2°) from linearity,
indicating the presence of considerable strain in this system.
Accordingly, the heat of formation per one ethynylcyclobutene
unit of 43 (98.3 kcal/mol) is larger than those of 44 (94.0 kcal/
mol) and 45 (94.3 kcal/mol). On the contrary, there seems to
be little strain in tetramer 44, the most stable congener of this
series, which has planar geometry of the annulene core because
of the right angles at the corners. Moreover, tetramer 44 has
the smallest HOMO-LUMO gap in accord with its planar
structure. The structure of the pentamer 45, however, is not
planar; the angle θ is smaller than 90°, and the acetylene bond
is bending slightly inward to the annulene ring. Despite the
presence of the largest number of the π bonds, the HOMO-
LUMO gap of 45 is the largest of the three, which is also
indicative of nonplanarity of the annulene ring. On the other
hand, in the series of the parent compounds 46-48, trimer 46
turns out to be the least strained because of the best fit angle θ
(65.8°) for the planar geometry. Planar 46 has the lowest
HOMO-LUMO gap of the three. To reduce the angle strain
around angles R and θ, the structures of tetramer 47 and
pentamer 48 become nonplanar, rendering their heats of
formation per enyne unit similar to one another (65.8, 65.0, and
65.7 kcal/mol, respectively).
Figure 4. Negative mode LD-TOF mass spectrum of oxanorborna-
diene-annelated dehydro[18]annulene 40. R denotes the furan fragment.
Scheme 9
In accord with the calculated HOMO-LUMO gaps for the
model compounds, the end absorptions of the electronic spectra
of planar 12 and 13 extend beyond 500 nm, while nonplanar
14 does not have absorptions at >500 nm as shown in Figure
butadiyne-bridged compounds 15 and 16, in conjunction with
low volatility precluded their isolation in rigid glass as well as
crystalline noble gas matrices. Also, low volatility of these
compounds precluded experiments on the thermal fragmentation.
Structures and Spectroscopic Properties of Dehydroan-
nulenes Annelated by [4.3.2]Propellatriene and Oxanorbor-
nadiene Units. Finally, the structure and spectroscopic prop-
erties of the dehydroannulenes annelated by the propellatriene
units and/or the oxanorbornadiene units are discussed. The
parent hydrocarbons as well as a number of derivatives
possessing dodecadehydro[18]- and hexadecadehydro[24]-
annulene systems are known,14-16,38,39 and the effect of fusion
of cyclobutene rings on the structural and spectroscopic proper-
ties of these dehydroannulene ring systems has already been
discussed.42 The spectral properties of dehydroannulenes 15 and
16 are in accord with this view. Namely, the electronic spectra
of 15 and 16 are similar to those of the corresponding
cyclobutene-annelated dehydroannulenes.42 In the 1H NMR
spectra, the signals due to the vinyl protons (H2 and H5 of the
propellane unit) of 15 which are closer to the bridgeheads of
the propellane units appear at about 0.3 ppm lower field than
those of the reference compound 17c owing to the diamagnetic
ring current of the [18]annulene perimeters. On the other hand,
the corresponding signals of 16 appear at about 0.3 ppm higher
field than those of 17c because of the paratropic character of
the [24]annulene core.
1
6. In addition, in the H NMR spectra, the vinyl protons (H2
and H5) adjacent to the bridgeheads of the propellane units of
12 and 13 appear about at 0.5 and 0.4 ppm higher field,
respectively, than those of the reference compound 17c owing
to the paramagnetic ring current of the [12]- and [16]annulene
perimeters. By contrast, the corresponding signals of 14 resonate
at only 0.2 ppm higher field than those of 17c because of its
nonplanar structure, although 14 also has a 20π electronic
system.
Within the series of dehydro[18]annulenes 15 and 38-40
annelated by the propellatriene and/or oxanorbornadiene units,
the absorption bands in the electronic spectra exhibit steady
bathochromic shifts with an increasing number of the oxanor-
bornadiene units in the molecule as shown in Figure 7,
presumably as a result of through-bond interaction between the
norbornadiene and dehydroannulene π systems. Moreover, the
σ-π conjugative interaction between the strained σ bonds of
the oxanorbornadiene units and the π bonds of the annulene
ring may also responsible for the bathochromic shift, because
remarkable electron-donating effect of the bicyclo[2.2.2]octane
unit was observed by Komatsu et al. in the dehydroannulene
systems related to 38-40.38g The kinetic stabilities of the
dehydroannulenes 39 and 40 with more than one oxanorbor-
nadiene unit are substantially less than those of 17 and 38; the
less sterically hindered compounds 39 and 40 exploded mildly
when they were scratched with a spatula and decomposed
gradually even in the solid state under inert atmosphere.
To assess the geometries and stabilities of the propellatriene-
annelated dehydroannulenes 12-14, semiempirical AM1 cal-
culations for the corresponding cyclobutene-annelated dehy-
droannulenes 43-45 were carried out (Figure 5). For comparison,
AM1 calculations were also undertaken for the corresponding
parent annulenes 46-48 which do not have the fused cy-
clobutene rings. Selected geometrical parameters, heats of
In conclusion, we have prepared dehydro[12]-, [16]-, [18]-,
[20]-, and [24]annulenes 12-16 annelated by [4.3.2]propella-
triene units as possible precursors to the corresponding cyclo-
[n]carbons of n ) 12, 16, 18, 20, and 24. The model study of
the photolysis for the simple propellatriene derivatives 17a, 17b,
(42) Li, Y.; Rubin, Y.; Diederich, F.; Houk, K. N. J. Am. Chem. Soc.
1990, 112, 1618.

1770 J. Am. Chem. Soc., Vol. 122, No. 8, 2000
Tobe et al.
Figure 5. AM1-calculated geometries of the cyclobutane-annelated dehydroannulenes 43-45 and their parent compounds 46-48.
Table 1. AM1-calculated Geometries and Energies for
Cyclobutene-annelated Dehydroannulenes 43-45 and Their Parent
Hydrocarbons 46-48a
bond angle (deg)
∆Hf°
(kcal/mol)
HOMO-LUMO
compd
R
â
θ
gap (eV)
43
44
45
46
47
48
129.8
135.6
170.2
179.7
79.6
91.2
294.8
375.9
471.4
197.3
259.9
328.7
6.42
6.23
6.73
7.15
7.78
7.81
137.1b 178.3b 94.1b
122.9
125.6
177.0
178.7
65.8
71.2
125.9b 175.7b 77.2b
a The angles R, â, and θ are indicated in Figure 1. b The averages
of the angles because of the absence of symmetry in the optimized
geometry.
Figure 7. UV-vis spectra of propellane-annelated dehydro[18]-
annulene derivatives 15 (solid line, 1.09 × 10-5 M), 38 (dashed line,
1.50 × 10-5 M), 39 (dotted line, 1.91 × 10-5 M), and 40 (dashed and
dotted line, 1.57 × 10-5 M) in chloroform. The vertical scales for the
spectra of 38-40 are shifted by 0.1, 0.2, and 0.3 units, respectively,
for clarity.
losses of indane fragments. Solution photolysis of 13 and 15 in
furan gave rise to the Diels-Alder adducts 38-40 and 42,
respectively, derived from reactive polyynes formed by [2 +
2] cycloreversion. Finally, it is worth noting that this technique
was successfully applied to the generation of a three-dimensional
polyyne C60H6 which eventually isomerized to C60 fullerene.43
Figure 6. UV-vis spectra of propellane-annelated dehydro[12]-
annulene 12 (solid line, 1.04 × 10-6 M), dehydro[16]annulene 13
(dashed line, 3.43 × 10-6 M), and dehydro[20]annulene 14 (dotted
line, 2.17 × 10-6 M) in chloroform.
Experimental Section
1H NMR (500 or 270 MHz) and 13C NMR (125.65 or 67.5 MHz)
were recorded on a JEOL JNM-GX-500 or a JNM-GSX-270 spec-
trometer. The assignments of the number of the attached hydrogen(s)
to the carbon atoms in the 13C NMR spectra were determined by the
and 18 by UV irradiation revealed that the [2 + 2] cyclorever-
sion takes place efficiently to give the corresponding linear
polyynes 28a, 28b, and 31. The negative mode LD-TOF mass
spectra of the cyclocarbon precursors 12-16 exhibit the
corresponding cyclocarbon anions formed by the successive
(43) Tobe, Y.; Nakagawa, N.; Naemura, K.; Wakabayashi, T.; Shida,
T.; Achiba, Y. J. Am. Chem. Soc. 1980, 102, 4544. See also: Rubin, Y.;
Parker, T. C.; Pastor, S. J.; Jalistagi, S.; Boulle, C.; Wilkins, C. L. Angew.
Chem., Int. Ed. 1998, 37, 1226.

CycloreVersion of [4.3.2]Propella-1,3,11-trienes
J. Am. Chem. Soc., Vol. 122, No. 8, 2000 1771
DEPT experiments, where the signs q, t, s, and p denote quaternary,
tertiary, secondary, and primary carbons, respectively. IR and UV-
vis spectra were taken on Hitachi 260-10 and 220A spectrometers,
respectively. EI and FAB mass spectra were recorded on a JEOL JMS-
DX303HF spectrometer. The laser-desorption time-of-flight (LD-TOF)
mass spectra were obtained on a home-built spectrometer equipped with
a Nd:YAG laser (266 nm, typically 0.6 mJ/pulse).23 Preparative HPLC
separation was undertaken with a JAI LC-908 chromatograph using
600 mm × 20 mm JAIGEL-1H and 2H GPC columns with CHCl3 as
an eluent.
Hz, 2H), 4.56 (AB, J ) 6.4 Hz, ∆ν ) 15.1 Hz, 2H), 4.25 (d, J ) 12.1
Hz, 1H), 3.99 (s, 2H), 3.97 (br s, 2H), 3.89 (br d, J ) 12.1 Hz, 1H),
3.37 (s, 3H), 3.35 (s, 3H), 2.37 (dd, J ) 16.3, 6.9 Hz, 1H), 2.05 (dd,
J ) 12.6, 5.9 Hz, 1H), 1.86-1.73 (m, 3H), 1.64-1.48 (m, 1H), 1.27
(ddd, J ) 12.6, 12.6, 6.7 Hz, 1H), 1.09 (ddd, J ) 12.4, 12.4, 6.7 Hz,
1H); IR (neat) 3450, 1640, 1215, 1150, 1100, 1040, 940, 920 cm-1
.
To a solution of the above product dissolved in 15 mL of 1,2-
dichloroethane was added 909 mg (9.00 mmol) of triethylamine
followed by 2.11 g (9.00 mmol) of 2,4-dinitrophenylsulfenyl chloride.
The resulting suspension was heated under reflux for 6 h. The mixture
was diluted with hexane (30 mL) and filtered. The filtrate was
concentrated, and the dark red residue was extracted several times with
hexane. The solvent was evaporated, and the residue was chromato-
graphed on silica gel to give 749 mg (83%) of triene 21a as a colorless
Preparation of 11,12-Diethynyl[4.3.2]propella-1,3,11-trienes (17a-
c). Method A: Through Diformylpropellatriene 22. 11,12-Bis-
[(methoxymethoxy)methyl][4.3.2]propell-11-en-1-one (19a). A so-
lution of 5.29 g (39.0 mmol) of enone 1125 and 57.0 g (328 mmol) of
1,4-bis(methoxymethoxy)-2-butyne26 in 40 mL of CH2Cl2 was irradiated
through a Pyrex filter with a 500-W high-pressure mercury lamp at
room temperature. After every 2 to 2.5 h, about a 5-g quantity of enone
11 in 20 mL of CH2Cl2 was added three times. The total amount of 11
used was 20.8 g (0.153 mol), and the irradiation was continued until
GLC monitoring showed no change in the relative peak areas of the
alkyne and the product. After evaporation of the solvent, the mixture
was distilled under reduced pressure (79-81 °C/1 mmHg) to recover
the unreacted alkyne. The residue was chromatographed on silica gel
to afford 32.8 g (70%) of the cycloadduct 19a as a pale yellow oil. 1H
NMR (CDCl3) δ 4.64 (s, 2H), 4.57 (AB, J ) 6.4 Hz, ∆ν ) 9.3 Hz,
2H), 4.15 (s, 2H), 4.04 (AB, J ) 13.1 Hz, ∆ν ) 38.0 Hz, 2H), 3.39 (s,
3H), 3.35 (s, 3H), 2.56 (ddd, J ) 17.8, 6.0, 2.7 Hz, 1H), 2.23-1.33
(m, 10H), 1.13 (ddd, J ) 12.4, 12.4, 6.7 Hz, 1H); 13C NMR (CDCl3)
δ 214.0 (q), 143.8 (q), 137.0 (q), 95.9 (s), 95.8 (s), 64.8 (q), 60.9 (s),
60.5 (s), 56.9 (q), 55.04 (p), 54.99 (p), 38.7 (s), 31.7 (s), 30.7 (s), 25.5
(s), 22.7 (s), 20.0 (s); IR (neat) 1690, 1150, 1100, 1040 cm-1; MS m/z
310 (M+). Semicarbazone, mp 143-145 °C. Found: C, 58.96; H, 7.91;
N, 11.44%. Calcd for C18H29O5N3: C, 58.83; H, 7.96; N, 11.11%.
11,12-Bis[(methoxymethoxy)methyl][4.3.2]propella-2,11-dien-1-
one (20a). To a solution of 1.91 g (6.17 mmol) of 19a and 1.25 g
(12.3 mmol) of triethylamine in 12 mL of CCl4 was added dropwise
1.51 g (6.79 mmol) of trimethylsilyl trifluoromethanesulfonate, and the
resulting mixture was stirred at room temperature for 6 h. The mixture
was diluted with NaHCO3 solution and was extracted with CH2Cl2.
The extract was washed with saturated NaCl solution and then dried
over MgSO4. The solvent was evaporated, and the residue was extracted
with hexane ( ∼50 mL) to remove brown tarry material. The solvent
was evaporated, and the residue was dissolved in 6 mL of acetonitrile.
To this solution was added 680 mg (3.03 mmol) of Pd(OAc)2 and a
solution of 324 mg (3.00 mmol) of p-benzoquinone in 20 mL of the
same solvent, and the mixture was stirred at 30 °C. After 16 h, another
portion of Pd(OAc)2 (450 mg, 2.00 mmol) was added, and the reaction
was continued for another 29 h. The mixture was filtered, and the filtrate
was concentrated under reduce pressure. The residue was chromato-
graphed on silica gel to give 1.01 g (53%) of dienone 20a as a pale
yellow oil. 1H NMR (CDCl3) δ 6.57 (ddd, J ) 10.1, 5.4, 2.7 Hz, 1H),
5.94 (ddd, J ) 10.1, 2.7, 1.7 Hz, 1H), 4.54 (s, 2H), 4.50 (AB, J ) 6.4
Hz, ∆ν ) 9.5 Hz, 2H), 4.09 (s, 2H), 3.95 (s, 2H), 3.31 (s, 3H), 3.29 (s,
3H), 2.88 (ddd, J ) 19.8, 5.7, 1.7 Hz, 1H), 2.28 (ddd, J ) 19.8, 2.7,
2.7 Hz, 1H), 2.06-1.93 (m, 2H), 1.69-1.48 (m, 2H), 1.30 (ddd, J )
12.6, 12.6, 6.9 Hz, 1H), 1.12 (ddd, J ) 12.4, 12.4, 6.7 Hz, 1H); 13C
NMR (CDCl3) δ 202.2 (q), 144.7 (t), 142.7 (q), 141.5 (q), 127.4 (t),
95.8 (s), 62.7 (q), 60.6 (s), 60.4 (s), 55.2 (q), 55.1 (p), 52.0 (p), 33.8
(s), 32.9 (s), 25.7 (s), 22.5 (s); IR (neat) 1765, 1150, 1100, 1040, 940,
915, 835 cm-1; MS m/z 308 (M+). HRMS found, 308.1631. Calcd for
C17H24O5, 308.1623.
1
oil. H NMR (CDCl3) δ 5.84-5.70 (m, 4H), 4.55 (AB, J ) 6.9 Hz,
∆ν ) 8.0 Hz, 4H), 4.06 (AB, J ) 12.9 Hz, ∆ν ) 15.0 Hz, 4H), 3.32
(s, 6H), 1.87 (dd, J ) 12.6, 5.7 Hz, 2H),1.58-1.29 (m, 2H), 1.13 (ddd,
J ) 12.2, 12.2, 6.7 Hz, 2H); 13C NMR (CDCl3) δ 141.8 (q), 130.4 (t),
120.6 (t), 95.5 (s), 60.0 (s), 55.1 (p), 53.2 (q), 32.2 (s), 18.8 (s); IR
(neat) 1650, 1155, 1105, 1050 915, 720 cm-1; MS m/z 292 (M+).
HRMS found, 292.1689. Calcd for C17H24O4, 292.1675.
11,12-Bis(hydroxymethyl)[4.3.2]propella-1,3,11-triene (21c). To
a solution of 5.68 g (19.4 mmol) of 21a in 190 mL of THF was added
90 mL of 4N HCl, and the solution was stirred at 40 °C for 6 h. After
most of THF was removed, the mixture was neutralized with NaHCO3
and extracted with ether. The extract was washed with saturated NaCl
solution and then dried over MgSO4. The solvent was evaporated, and
the residue was chromatographed on silica gel to give 2.69 g (68%) of
diol 21c as a white solid: mp 96-98 °C; 1H NMR (CDCl3) δ 5.76 (s,
4H), 4.26-4.04 (m, 4H), 4.02 (br s, 2H), 1.79 (dd, J ) 12.9, 5.7 Hz,
2H),1.62-1.35 (m, 2H), 1.14 (ddd, J ) 12.3, 12.3, 6.7 Hz, 2H); 13C
NMR (CDCl3) δ 142.0 (q), 130.3 (t), 121.0 (t), 56.2 (s), 53.4 (q), 31.7
(s), 18.8 (s); IR (KBr) 1570, 1065, 1000, 995, 775, 710 cm-1; MS m/z
204 (M+). HRMS found, 204.1151. Calcd for C13H16O2, 204.1150.
Preparation of Diol 21c through Acetates 19b, 20b, and 21b. A
solution of 2.30 g (16.9 mmol) of enone 1125 and 15.8 g (92.9 mmol)
of 1,4-diacetoxy-2-butyne in 20 mL of CH2Cl2 was irradiated through
a Pyrex filter with a 500-W high-pressure mercury lamp at room
temperature for 9 h. After removal of the alkyne by distillation under
reduced pressure (110-130 °C/15 mmHg), distillation (135-145 °C/
0.5 mmHg) afforded 2.17 g (62%) of the cycloadduct 19b as a pale
yellow oil. IR (neat) 1740, 1680, 1220, 1020 cm-1
.
A mixture of 53.2 g (0.174 mol) of 19b and 57.8 g (0.191 mol) of
5,5-dibromo-2,2-dimethyl-1,3-dioxane-4,6-dione44 in 365 mL of CCl4
was heated under reflux for 23 h. During the reaction another portion
od bromide (15.6 g, 51.8 mmol) was added. The mixture was cooled,
and a saturated solution of NaHCO3 was added. The organic layer was
separated,washed with 0.2 M Na2S2O3 and saturated NaCl solutions,
and then dried over MgSO4. The aqueous solution was extracted with
ether, and the ether extract was treated similarly. The crude bromo
ketone obtained from both extracts was combined and used for the
next step without purification. To a solution of anhydrous LiBr (74.2
g, 0.855 mol) and Li2CO3 (63.2 g, 0.855 mol) in 320 mL of DMF was
added dropwise a solution of the above product in 65 mL of DMF.
The mixture was heated at 80 °C for 2 h and then at 110 °C for 4 h.
After cooling, the mixture was diluted with water and filtered. The
filtrate was extracted with ether, and the extract was washed with
saturated NaCl solution and then dried (MgSO4). Chromatography on
1
silica gel gave dienone 20b as a yellow oil (30.4 g, 57%). H NMR
(CDCl3) δ 6.62 (ddd, J ) 10.3, 5.5, 2.8 Hz, 1H), 5.99 (ddd, J ) 10.1,
2.8, 1.7 Hz, 1H), 4.65 (s, 2H), 4.57 (AB, J ) 15.2 Hz, ∆ν ) 38.2 Hz,
2H), 2.85 (ddd, J ) 19.8, 5.4, 1.7 Hz, 1H), 2.31 (ddd, J ) 19.8, 2.8,
2.8 Hz, 1H), 2.08 (s, 3H), 2.04 (s, 3H), 2.10-1.97 (m, 2H), 1.83-
1.72 (m, 1H), 1.65-1.47 (m, 1H), 1.43-1.30 (m, 1H), 1.25-1.12 (m,
1H); IR (neat) 1730, 1660, 1220, 1020 cm-1; MS m/z 308 (M+ + 1).
HRMS found, 305.1364. Calcd for C17H21O5, 305.1389.
The transformation of 814 mg (2.67 mmol) enone 20b into triene
21b was carried out as described for the corresponding reaction of 20a,
giving 21b (486 mg) in 66% yield as a pale yellow oil. 1H NMR
11,12-Bis[(methoxymethoxy)methyl][4.3.2]propella-1,3,11-
triene (21a). To a solution of 950 mg (3.08 mmol) of 20a in 15 mL of
MeOH cooled in an ice bath was added 1.27 g (3.40 mmol) of cerium
trichloride heptahydrate followed by portionwise addition of 114 mg
(3.00 mmol) of sodium borohydride. After 1 h, the mixture was diluted
with water and extracted with CH2Cl2. The extract was washed with
water and dried over MgSO4. The solvent was evaporated to give the
corresponding alcohol, which contained only one diastereomer as judged
from its 1H NMR spectrum. 1H NMR (CDCl3) δ 5.72 (dd, J ) 9.6, 3.0
Hz, 1H), 5.61 (br t, J ) 9.4 Hz, 1H), 4.64 (AB, J ) 6.4 Hz, ∆ν ) 21.2
(44) Snyder, H. R.; Kruse, C. W. J. Am. Chem. Soc. 1958, 80, 1942.

1772 J. Am. Chem. Soc., Vol. 122, No. 8, 2000
Tobe et al.
(CDCl3) δ 5.74 (s, 4H), 4.59 (s, 4H), 2.02 (s, 6H), 1.83 (dd, J ) 5.6,
12.1 Hz, 2H), 1.53 (dt, J ) 12.1, 6.6 Hz, 1H), 1.34 (dtt, J ) 5.6, 6.6,
12.1 Hz, 1H), 1.12 (ddd, J ) 6.6, 12.1, 12.1 Hz, 2H); IR (neat) 1740,
1220, 1020, 720, 710 cm-1; MS m/z 288 (M+). HRMS found, 288.1346.
Calcd for C17H20O4, 288.1362.
A solution of 11.5 g (39.9 mmol) of 21b in 48 mL of MeOH was
added dropwise to a solution of 5.0 g (0.12 mol) of NaOH in 20 mL
of MeOH and 7.5 mL of water. The solution was stirred at room
temperature for 1.5 h, diluted with water, and extracted with ether.
The extract was washed with saturated NaCl solution and dried
(MgSO4). Chromatography on silica gel yielded 5.96 g (73%) of diol
21c as a white solid.
11,12-Diformyl[4.3.2]propella-1,3,11-triene (22). To a solution of
122 mg (0.60 mmol) of 21c in 8 mL of CH2Cl2 was added 1.36 g
(15.6 mmol) of activated MnO2, and the mixture was stirred at room
temperature for 4 h. The mixture was filtered, and the filtrate was
concentrated. Chromatography on silica gel gave 94 mg (78%) of
dialdehyde 22 as a yellow solid: mp 118-120 °C dec; 1H NMR
(CDCl3) δ 10.03 (s, 2H), 5.97-5.86 (m, 4H), 2.16-2.10 (m, 2H), 1.73-
1.63 (m, 1H), 1.44-1.22 (m, 3H); 13C NMR (CDCl3) δ 184.9 (t), 149.2
(q), 127.4 (t), 122.6 (t), 53.7 (q), 32.6 (s), 18.9 (s); IR (KBr) 1675,
1665, 1285, 1170, 715, 700 cm-1; MS m/z 200 (M+). HRMS found,
200.0824. Calcd for C13H12O2, 200.0837.
17b: mp 75-78 °C; 1H NMR (CDCl3) δ 5.88-5.77 (m, 4H), 1.94
(dd, J ) 12.6, 5.4 Hz, 2H), 1.63-1.38 (m, 2H), 1.25-1.13 (m, 2H),
0.93 (s, 18H), 0.11 (s, 12H); 13C NMR (CDCl3) δ 133.2 (q), 128.7 (t),
121.7 (q), 99.4 (q), 97.3 (q), 55.8 (q), 32.8 (s), 26.1 (p), 18.7 (s), 16.6
(q), -4.7 (p); IR (KBr) 2130, 1250, 1020, 860, 840, 820, 810, 770
cm-1; UV (cyclohexane) λmax (log ꢀ) 304 (4.22), 288 (4.18), 265 (4.38),
255 (4.28) nm; MS m/z 420 (M+). HRMS found, 420.2669. Calcd for
C27H40Si2, 420.2668.
24: 1H NMR (CDCl3) δ 5.68-5.61 (m, 4H), 2.06-1.83 (m, 2H),
1.68-1.17 (m, 4H), 0.93, 0.90, 0.89, 0.886, 0.882, 0.876, 0.872 (s,
total 30H), 0.12, 0.11, 0.094, 0.085, 0.07, 0.066, 0.045, 0.042, 0.032,
0.017 (s, total 18H); 13C NMR (CDCl3) δ 209.6, 209.5 (q), 202.7, 202.1
(q), 130.0, 129.7, 129.5 (t), 119.2, 119.1, 119.0, 118.9 (t), 106.9, 106.8
(q), 104.7, 104.7, 104.4 (q), 98.4, 98.3 (q), 94.4, 94.3 (q), 53.7, 53.5
(q), 52.40, 52.36 (q), 40.1, 40.0 (s), 39.7, 39.5 (s), 31.8, 31.7 (s), 31.4,
31.3 (s), 27.6, 27.4, 27.3, 27.2, 27.1, 26.9 (p), 22.8, 22.7 (s), 19.7 (s),
18.0, 17.8, 17.7, 17.5, 17.4 (q), 14.11, 14.10 (p), -2.5, -2.6 (p), -3.0,
-3.1, -3.3 (p), -3.6, -3.8 (p), -5.5, -5.55, -5.64 (p); IR (neat)
1880, 1250, 1000, 870, 850, 830, 810, 770 cm-1; UV (cyclohexane)
λmax (log ꢀ) 304 (4.22), 288 (4.18), 265 (4.38), 255 (4.28) nm; MS m/z
420 (M+). HRMS found, 420.2669. Calcd for C27H40Si2, 420.2668.
11,12-Diethynyl[4.3.2]propella-1,3,11-triene (17c). To a solution
of 56 mg (0.13 mmol) of 17b in a mixture of THF and water (95:5,
v/v, 3 mL) was added 330 mL (0.33 mmol) of 1.0M Bu4NF solution
in THF and the mixture was stirred at room temperature for 2 h. The
solvent was removed under reduced pressure, and the residue was
directly subjected to flash chromatography to afford 20 mg (78%) of
17c as a colorless oil which turned dark under vacuum at room
temperature. Deprotection of 17a was similarly undertaken. Because
of its thermal lability, this compound was not thoroughly purified when
11,12-Bis(2,2-dichloroethenyl)[4.3.2]propella-1,3,11-triene (23).
To a solution of 710 µL (3.67 mmol) of diethyl trichloromethylphos-
phonate45 in 1.4 mL of ether and 1.1 mL of THF, cooled to -100 °C
in a MeOH-liquid N2 bath, was added dropwise 1.9 mL (3.1 mmol)
of 1.6 M BuLi in hexane. The mixture was stirred for 15 min, then a
solution of 61 mg (0.30 mmol) of dialdehyde 22 in 1 mL of ether-
THF (1:1, v/v) was added dropwise. The solution was stirred at -100
°C for 3 h and then warmed to room-temperature slowly. The mixture
was diluted with 10% HCl and extracted with ether. The extract was
washed with saturated NaCl solution and dried over MgSO4. After
removal of the solvent, the residue was chromatographed on silica gel
to afford 79 mg (78%) of tetrachloride 23 as a white solid: mp 143-
1
it was used for the subsequent transformations. H NMR (CDCl3) δ
5.92-5.79 (m, 4H), 3.21 (s, 2H), 1.95 (dd, J ) 12.9, 5.7 Hz, 2H),
1.66-1.35 (m, 2H), 1.28-1.16 (m, 2H); IR (neat) 3280, 840, 840, 780
cm-1; MS m/z 192 (M+). HRMS found, 192.0928. Calcd for C15H12,
192.0939.
1
144 °C; H NMR (CDCl3) δ 6.48 (s, 2H), 6.16-6.12 (m, 2H), 5.90-
Method B: Through Dichloropropellatriene 27. 11,12-Dichloro-
[4.3.2]propellan-1-one (25). A solution of 27.4 g (0.201 mol) of enone
11 in 112 mL of trichloroethene (ca. 1.2 mol) was irradiated with a
500-W high-pressure mercury lamp for about 70 h. After removal of
the solvent, the residue was distilled under reduced pressure (140 °C/1
mmHg) to give 44.2 g (82%) of the cycloadducts as a brown solid. A
portion of this sample was purified by chromatography on silica gel to
afford a white solid. NMR spectra of this product indicated that it was
a mixture of three regio- and stereoisomers. 1H NMR (CDCl3) δ 5.03,
4.98, 4.53 (s, ratio 1:3:4.5, total 1H), 2.6-1.5 (m, 13H); 13C NMR
(CDCl3) δ 211.0, 207.6, 207.2 (q), 93.6, 88.0, 87.8 (q), 74.2, 70.8,
70.0 (t), 68.8, 66.6, 65.8 (q), 59.7, 52.5, 51.9 (q), 40.1, 39.8, 39.6 (s),
37.5, 37.2, 37.0 (s), 36.9, 35.3, 33.1 (s), 34.0, 31.9, 26.0 (s), 26.9, 25.1,
5.86 (m, 2H), 2.30-2.14 (m, 2H), 1.49-1.24 (m, 4H); 13C NMR
(CDCl3) δ 140.3 (q), 129.3 (t), 122.1 (q), 121.4 (t), 120.3 (t), 54.7 (q),
35.2 (s), 18.7 (s); IR (KBr) 1585, 920, 895, 850, 780, 700 cm-1; MS
m/z 334 (M+). Anal. Found: C, 53.73; H, 3.51. Calcd for C15H12Cl4:
C, 53.93; H, 3.62.
11,12-Bis[(trimethylsilyl)ethynyl][4.3.2]propella-1,3,11-triene (17a).
To a mixture of ether and THF (1:1, v/v, 0.8 mL) cooled in an ethanol-
dry ice bath was added 910 µL (1.48 mmol) of 1.6 M BuLi followed
by a solution of 90 mg (0.27 mmol) of tetrachloride 23 in 1.5 mL of
the same solvent. After 3 h, 200 µL (1.58 mmol) of Me3SiCl was added
dropwise, and the mixture was stirred for 1.5 h before NaHCO3 solution
was added. The mixture was warmed to room temperature and extracted
with ether. The extract was washed with saturated NaCl solution and
dried (MgSO4). Removal of the solvent followed by flash chromatog-
24.0 (s), 21.5, 19.8, 18.6 (s); IR (KBr) 1700, 820, 725 cm-1
.
To a solution of 27.8 g (0.298 mol) of t-BuOK in 200 mL of DMSO
was added dropwise a solution of the above ketone in 180 mL of THF.
The mixture was stirred at room temperature for 1.5 h and then diluted
with water and extracted with ether. The extract was washed with water
and saturated NaCl solution and then dried (MgSO4). After removal of
the solvent, 34.9 g (92%) of 25 was isolated by distillation under
reduced pressure (79-95 °C/0.3 mmHg) as a pale yellow oil. 1H NMR
(CDCl3) δ 2.62-2.51 (m, 1H), 2.25-2.12 (m, 2H), 2.01-1.75 (m, 5H),
1.65-1.36 (m, 3H), 1.24-1.12 (m, 1H); 13C NMR (CDCl3) δ 209.5
(q), 129.4 (q), 122.0 (q), 68.8 (q), 62.6 (q), 38.7 (s), 30.6 (s), 29.0 (s),
24.9 (s), 22.0 (s), 19.3 (s); IR (neat) 1700, 1630, 1060, 1040, 1030,
970, 890, 820, 740 cm-1; MS m/z 230 (M+). HRMS found, 230.0206.
Calcd for C11H12Cl2O, 260.0265.
1
raphy gave 71 mg (78%) of 17a as a colorless oil. H NMR (CDCl3)
δ 5.88-5.77 (m, 4H), 1.94 (dd, J )12.6, 5.7 Hz, 2H), 1.63-1.37 (m,
2H), 1.25-1.12 (m, 2H), 0.19 (s, 18H); 13C NMR (CDCl3) δ 133.2
(q), 128.7 (t), 121.7 (q), 101.1 (q), 96.5 (q), 55.8 (q), 32.7 (s), 18.7 (s),
-0.1 (p); IR (neat) 2120, 1240, 1020, 870, 840, 750 cm-1; UV
(cyclohexane) λmax (log ꢀ) 303 (4.19), 287.5 (4.14), 265 (4.37), 255
(4.27) nm; MS m/z 336 (M+). HRMS found, 336.1724. Calcd for
C21H28Si2, 336.1730.
11,12-Bis[(tert-butyldimethylsilyl)ethynyl][4.3.2]propella-1,3,11-
triene (17b). To a mixture of ether and THF (1:1, v/v, 4.6 mL) cooled
in an ethanol-dry ice bath was added 7.0 mL (11 mmol) of 1.6 M BuLi
followed by a solution of 538 mg (1.61 mmol) of tetrachloride 23 in
12 mL of the same solvent. After 2 h, the mixture was warmed to 0
°C, and 1.60 g (10.6 mmol) of t-BuMe2SiCl in 7 mL of ether was
added dropwise, and the mixture was stirred for 2 h before NaHCO3
solution was added. The mixture was extracted with ether, and the
extract was washed with saturated NaCl solution and then dried
(MgSO4). Removal of the solvent followed by flash chromatography
gave 325 mg (48%) of 17b as a white solid together with 300 mg
(31%) of bisallene 24 as a colorless oil.
11,12-Dichloro[4.3.2]propella-2,11-dien-1-one (26). Bromination
of 42.0 g (0.182 mol) of ketone 25 followed by dehydrobromination
was carried out as described for the corresponding transformation of
diacetate 19b described above to give 31.9 g (75%) of 26 as a pale
yellow oil which solidified on standing: bp 80 °C/0.6 mmHg; mp 88-
89 °C; 1H NMR (CDCl3) δ 6.66 (ddd, J ) 10.3, 5.6, 2.7 Hz, 1H), 6.04
(ddd, J ) 10.3, 2.8, 1.8 Hz, 1H), 2.88 (ddd, J ) 9.9, 5.6, 1.6 Hz, 1H),
2.33 (ddd, J ) 9.8, 2.8, 2.8 Hz, 1H), 2.10 (ddd, J ) 12.7, 5.4, 2.6 Hz,
(45) Kosolapoff, G. M. J. Am. Chem. Soc. 1947, 69, 1002.
2H), 1.88-1.79 (m, 1H), 1.66-1.34 (m, 2H), 1.29-1.18 (m, 1H); 13
C

CycloreVersion of [4.3.2]Propella-1,3,11-trienes
J. Am. Chem. Soc., Vol. 122, No. 8, 2000 1773
NMR (CDCl3) δ 197.8 (q), 144.4 (t), 128.1 (q), 127.2 (t), 125.6 (q),
66.7 (q), 57.5 (q), 32.5 (s), 31.3 (s), 24.9 (s), 21.8 (s); IR (KBr) 1660,
1630, 1060, 1000, 980, 970, 880, 810, 770, 720 cm-1; MS m/z 228
(M+). HRMS found, 228.0082. Calcd for C11H10Cl2O, 228.109.
11,12-Dichloro[4.3.2]propella-1,3,11-triene (27). Sodium borohy-
dride reduction of 24.8 g (0.108 mol) of 26 and subsequent dehydration
was carried out as described for the corresponding transformation of
20a to give 16.4 g (71%) of 27 as a colorless oil. 1H NMR (CDCl3) δ
5.94-5.81 (m, 4H), 1.98 (dd, J ) 5.8, 12.7 Hz, 2H), 1.67-1.58 (m,
1H), 1.47-1.29 (m, 1H), 1.25-1.14 (m, 2H); 13C NMR (CDCl3) δ
127.7 (t), 124.5 (q), 122.3 (t), 59.1 (q), 31.0 (s), 18.3 (s); IR (neat)
1610, 1190, 1035, 970, 905, 855, 810, 740, 715 cm-1; MS m/z 212
(M+). HRMS found, 212.0152. Calcd for C11H10Cl2, 212.0160.
11,12-Bis[(triisopropylsilyl)ethynyl][4.3.2]propella-1,3,11-triene
(17d). A flask containing 188 mg (0.99 mmol) of CuI and 488 mg
(0.42 mmol) of Pd(PPh3)4 was charged with argon. A solution of 1.50
g (7.04 mmol) of 27 in 15 mL of benzene was added followed by 2.1
mL ( ∼21 mmol) of triethylamine. To this solution was added 3.9 mL
( ∼18 mmol) of (triisopropylsilyl)ethyne, and the mixture was stirred
at room temperature for 3 h. After dilution with ether, the mixture was
filtered, and the filtrate was washed with 5% HCl, water, and saturated
NaCl solution. After being dried (MgSO4), the solvent was removed
under reduced pressure. Flash chromatography gave 3.50 g (99%) of
17d as a pale yellow oil. 1H NMR (CDCl3) δ 5.91-5.81 (m, 4H), 1.97
(dd, J ) 5.4, 12.6 Hz, 2H), 1.64-1.46 (m, 2H), 1.34-1.01 (m, 2H),
1.10 (s, 42H); 13C NMR(CDCl3) δ 133.0 (q), 128.8 (t), 121.6 (t), 98.8
(q), 97.4 (q), 55.8 (q), 32.8 (s), 18.8 (s), 18.6 (p), 11.2 (t); IR (neat)
2130, 1250, 990, 880, 850, cm-1; MS m/z 504 (M+). HRMS found,
292.1689. Calcd for C17H24O4, 292.1675.
and 4 mg (6%) a mixture of 29b and 30b in a ratio of 1:7 as a yellow
oil. Irradiation of 17b with a high-pressure mercury lamp gave 66% of
28b and 6% of 30b.
28b: 13C NMR (CDCl3) δ 88.6 (q), 86.2 (q), 61.7 (q), 26.0 (p),
16.8 (q), -5.0 (p).
1H NMR (CDCl3) δ for 29b: 5.88 (ddd, J ) 5.3, 2.3, 0.7 Hz, 1H),
5.58 (dd, J ) 5.2, 3.0 Hz, 1H), 3.34 (d, J ) 2.5 Hz, 1H), 2.68 (d, J )
3.0 Hz, 1H); for 30b: 5.80 (br s, 2H), 5.73 (AB, J ) 11.4 Hz, ∆ν )
42.0 Hz, 2H); 13C NMR (CDCl3) δ for 29a: 135.1 (t), 130.1 (q), 125.7
(t), 67.1 (q), 60.4 (q), 57.4 (t), 48.0 (t), 28.8 (s), 27.3 (s), 25.6 (s); for
30a: 141.9 (q), 139.1 (q), 132.3 (t), 131.3 (t), 131.1 (t), 130.1 (q),
130.0 (t), 128.8 (t), 105.1 (q), 104.2 (q), 98.1 (q), 97.1 (q), 37.6 (s),
36.5 (s), 26.2 (p), 22.5 (s), 16.7 (q), 16.6 (q), -4.5 (p); MS (for 1:7
mixture of 29b and 30b) m/z 420 (M+).
Photolysis of 11,12-Bis[(triisopropylsilyl)butadiynyl][4.3.2]propella-
1,3,11-triene (18). A solution of 45 mg (0.081 mmol) of 18 in 5 mL
of hexane, placed in a quartz tube, was irradiated with a 20-W low-
pressure mercury lamp under a nitrogen atmosphere in an ice bath for
12.5 h. After removal of the solvent, flash chromatography gave
decapentayne 3132 (26 mg, 74%) as a white solid. Indane was detected
in the crude product by 1H NMR and GLC, but any isomerization
product was not detected.
31: 13C NMR (CDCl3) δ 89.5 (q), 86.5 (q), 62.42 (q), 62.40 (q),
61.4 (q), 18.5 (p), 11.3 (t).
Photolysis of 11,12-Diethylidene[4.3.2]propella-1,3-diene (24). A
solution of 24 (50 mg, 0.084 mmol) in 0.8 mL of THF-d8 was irradiated
with a low-pressure mercury lamp as described above for 27 h. The
color of the solution turned reddish purple. Since an attempt to isolate
the product 32 by flash chromatography failed because of its lability,
13C NMR spectra were recorded directly at -20 °C, which indicated
the presence of only indane and 32. An aliquot of the photolysate was
diluted with cyclohexane to measure the UV-vis spectrum. IR spectrum
was recorded quickly after removal of the solvent in vacuo.
32: 13C NMR (THF-d8, -20 °C) δ 189.9 (q), 174.9 (q), 156.8 (q),
154.1 (q), 148.3 (q), 137.3 (q), 38.8 (s),32.3 (s), 27.28 (p), 27.26 (p),
27.1 (p), 23.4 (s), 20.2 (q), 19.4 (q), 19.2 (q), 14.5 (p), -3.60 (p),
-3.61 (p), -5.9 (p); IR (neat) 2060, 2040, 2000, 1960, 1880, 1820,
1600, 1250, 1060, 1020, 1000, 830, 800 cm-1; UV (cyclohexane) λmax
584, 527 nm.
Oxidative Coupling of Diethynylpropellatriene 17c: Propellane-
Annelated Dehydro[18]annulene 15 and Dehydro[24]annulene 16.
A mixture of diyne 17a (1.00 g, 2.97 mmol) and LiOH‚H2O (673 mg,
16.0 mmol) in 13.8 mL of THF and 3.7 mL of H2O was stirred at
room temperature for 1.5 h. After dilution with water, the mixture was
extracted with a mixture of pentane and THF (1:1, v/v). The extract
was dried over MgSO4 and then passed through a column of silica gel.
The solvent was evaporated and the residue, i.e., 17c, was diluted
immediately with 70 mL of a mixture of THF, methanol, and pyridine
(1:1:2, v/v) for the subsequent coupling reaction. To a solution of 3.78
g (20.8 mmol) of Cu(OAc)2 in 280 mL of a mixture of THF, methanol,
and pyridine (1:1:2, v/v) was added the above solution of 17c during
a 9 h-period under nitrogen atmosphere. Another portion of Cu(OAc)2
(1.62 g, 8.92 mmol) was added after 7 h. The mixture was stirred at
room temperature for a total of 33 h, while the flask was covered with
aluminum foils to protect the products from the room light. Most of
the solvent was removed under reduced pressure, and the residue was
treated with 10% HCl and benzene. The insoluble material was filtered
off, and the organic layer was separated, washed with saturated NaHCO3
solution, and then dried (MgSO4). The solvent was removed, and the
residue was chromatographed on silica gel. The product was washed
with a small amount of benzene to give 127 mg of trimer 15 as an
orange solid. Flash chromatography of the filtrate gave additional 15,
yielding a total amount of 211 mg. During the purification, care was
taken to protect the product from room light. Final purification was
conducted with preparative HPLC to give 166 mg (29% from 17c) of
15 (mixture of two diastereomers). In an other run which was
undertaken similarly, CHCl3 was used for extraction instead of benzene.
In this case a mixture of orange trimer 15 and carmine red tetramer 16
(mixture of four diastereomers) was obtained in a ratio of 13:1
(estimated by HPLC peak area, taking into account the relative
extinction coefficient) in 39% yield from 17c. Tetramer 16 was isolated
Similar reaction of 2.13 g (10.0 mmol) of 27 with (trimethylsilyl)-
ethyne gave 1.99 g (59%) of 12a which was identical to the sample
prepared from dialdehyde 22.
11,12-Bis[(triisopropylsilyl)butadinyl][4.3.2]propella-1,3,11-
triene (18). To a solution of 31 mg (0.43 mmol) of NH4OH‚HCl, 165
µL of 70% aqueous solution of ethylamine (2.05 mmol), and 6 mg
(0.06 mmol) of CuCl in 400 µL of methanol and THF (2:1, v/v) was
added a solution of 26 mg of diyne 17c (0.14 mmol) in 1.4 mL of the
same solvent. After 15 min, a solution of 118 mg (0.40 mmol) of
1-bromo-2-(triisopropylsilyl)ethyne32 in 800 µL of the same solvent
was added dropwise. The mixture was stirred at room temperature for
1 h, diluted with dilute HCl, and then extracted with ether. The extract
was washed with Na2CO3 solution and saturated NaCl solution and
then dried (MgSO4). Removal of the solvent followed by flash
chromatography gave 71 mg (95%) of tetrayne 18 as a colorless solid:
mp 145-147 °C; 1H NMR (CDCl3) δ 5.89-5.79 (m, 4H), 1.98 (dd, J
) 12.9, 5.4 Hz, 2H), 1.64-1.10 (m, 4H), 1.09 (s, 42H); 13C NMR
(CDCl3) δ 134.6 (q), 128.14 (t), 122.1 (t), 92.1 (s), 89.4 (q), 67.8 (q),
56.7 (q), 32.9 (s), 18.7 (s) 18.5 (p), 11.3 (t); IR (KBr) 2090, 995, 880,
760 cm-1; MS m/z 552 (M+). HRMS found, 552.3589. Calcd for C37H52-
Si2, 552.3608.
Photolysis of 11,12-Diethynyl[4.3.2]propella-1,3,11-trienes 17a
and 17b. A solution of 70 mg (0.21 mmol) of 17a in 5 mL of hexane,
placed in a quartz tube, was irradiated with a 20-W low-pressure
mercury lamp under a nitrogen atmosphere in an ice bath for 5 h. After
removal of the solvent, flash chromatography gave hexatriyne 28a32,34
(30 mg, 66%) together with an inseparable mixture of the isomerization
products 29a and 30a ( ∼1:1, 10 mg, 14%) as a yellow oil. Indane
was detected in the crude product by 1H NMR and GLC. Irradiation of
17a with a 500-W high-pressure mercury lamp through a Pyrex filter
afforded 28a together with 30a in 58 and 20% yields, respectively,
while 29a was not obtained under these conditions.
28a: 13C NMR (CDCl3) δ 87.9 (q), 87.4 (q), 61.9 (q), -0.6 (p).
1H NMR (CDCl3) δ for 29a: 5.90 (dd, J ) 4.8, 2.1 Hz, 1H), 5.58
(dd, J ) 5.3, 2.8 Hz, 1H), 3.34 (d, J ) 2.5 Hz, 1H), 2.69 (d, J ) 3.0
Hz, 1H); for 30a: 5.81 (br s, 2H), 5.75 (AB, J ) 11.1 Hz, ∆ν ) 44.8
Hz, 2H); 13C NMR (CDCl3) δ for 30a: 142.2 (q), 138.9 (q), 132.7 (t),
131.1 (t), 130.9 (t), 130.6 (q), 130.0 (t), 129.1 (q), 104.4 (q), 103.4
(q), 99.7 (q), 98.5 (q), 37.5 (s), 36.4 (s), 22.4 (t), 0.1 (p), 0.0 (p): MS
(for 1:1 mixture of 29a and 30a) m/z 336 (M+).
Irradiation of 66 mg (0.17 mmol) of 17b with a low-pressure mercury
lamp under similar conditions afforded 33 mg (67%) of triyne 28b32

1774 J. Am. Chem. Soc., Vol. 122, No. 8, 2000
Tobe et al.
by preparative HPLC. The absence of tetramer in the first run can be
ascribed to its low solubility of 16 in benzene.
(t), 127.3 (t), 125.1 (q), 122.7 (t), 121.7 (t), 82.4 (q), 73.3 (t), 59.5 (q),
55.7 (q), 32.1 (s), 31.5 (s), 18.4 (s); IR (neat) 3293, 2097, 1609, 1204,
1109, 1094, 938, 827, 753 cm-1; MS m/z 212 (M+). HRMS found,
212.05271. Calcd for C13H11Cl, 212.0549.
15 (mixture of two diastereomers with C3ν and Cs symmetry in an
1
approximate ratio of 1:3): dec 170 °C; H NMR (CDCl3) δ 6.22-
6.17 (m, 6H), 6.00-5.95 (m, 6H), 2.29 (dd, J ) 12.9, 6.0 Hz, 6H),
1.64 (ddd, J ) 12.8, 6.6, 6.2 Hz, 6H), 1.58-1.50 (m, 3H), 1.16 (ddd,
J ) 24.7, 6.6, 6.2 Hz, 3H); 13C NMR (CDCl3) δ 137.89, 137.88, 137.87,
137.85 (q), 128.90*, 128.85 (t)*, 122.21, 122.19, 122.18, 122.16 (t),
83.37‡, 83.35‡, 83.34†, 83.33‡ (q), 81.08‡, 81.07†, 81.04‡, 81.03‡ (q),
57.70, 57.69, 57.68 (q), 34.37, 33.35 (s), 19.01 (s). The intensities of
the signals marked by * are approximately twice as much as those of
the signals of similar environment. The sp carbon signals (indicated
Attempted Cyclization of 33b. To a solution of 10 mg (0.053 mmol)
of CuI, 148 mg (0.257 mmol) of Pd(PPh3)4, and 0.76 µL (0.77 mmol)
of butylamine in 2 mL of THF was added dropwise a solution of 52
mg (0.257 mmol) of 33b in 2.5 mL of THF under argon atmosphere.
The mixture was stirred at room temperature for 2 h and treated as
described for the preparation of 17d to yield 30 mg (58%) of the linear
dimer 34 (mixture of two diastereomers) as a white solid. Attempted
cyclization of 33b under different conditions invariably gave 34 as the
only isolable product but no cyclization products were detected. 34:
†
by ) for the minor C3ν isomer was identified by using a 90° pulse
radiation; under these conditions, the intensities of the signals of the
1
mp 145 °C dec; H NMR (CDCl3) δ 5.96-5.76 (m, 8H), 2.02-1.93
(m, 4H), 1.67-1.31 (m, 4H), 1.30-1.11 (m, 4H); 13C NMR (CDCl3)
δ 135.0 (q), 128.4 (t), 127.0 (t), 124.7 (q), 122.9 (t), 121.8 (t), 78.2
(q), 72.8 (q), 59.7 (q), 56.5 (q), 34.2 (s), 31.8 (s), 18.5 (s); IR (KBr)
3300, 1290, 1160, 1140, 960, 920, 900, 720 cm-1; MS m/z 402 (M+).
HRMS found, 402.0899. Calcd for C21H24O2, 402.0942.
C3ν isomer decreased relative to those of the corresponding signals
‡
(indicated by ) of the major Cs isomer: IR (KBr) 2140, 1070, 1045,
770, 720, 665 cm-1; UV-vis (CHCl3) λmax (log ꢀ) 539 (2.00) 484 (2.43),
415 (4.37), 403 (4.21), 356 (4.78) nm; LD-TOF MS see Figure 1.
16 (mixture of three diastereomers): dec 186 °C; 1H NMR (CDCl3:
CS2 ) 1:3) δ 5.81-5.78 (m, 8H), 5.55-5.50 (m, 8H), 1.76 (dd, J )
12.6, 5.2 Hz, 8H), 1.6-1.0 (m, 16H); IR (KBr) 2120, 1070, 1050, 720,
670 cm-1; UV-vis (CHCl3) λmax (log ꢀ) 427 (3.76), 369 (4.92), 348
(4.70) nm; LD-TOF MS see Figure 2. Because of the extremely limited
solubility of 16 in organic solvents, the 13C NMR spectrum of this
compound was not recorded.
Coupling of Chloroethynylpropellatriene 33a under Phase-
Transfer Conditions: Propellane-Annelated Dehydro[12]annulene
12, Dehydro[16]annulene 13, and Dehydro[20]annulene 14. A
mixture of 2.60 g (9.96 mmol) of 33a, CuI (190 mg, 1.00 mmol), Pd-
(PPh3)4 (1.15 g, 1.00 mmol), benzyltriethylammonium chloride (91 mg,
0.40 mmol) in 30 mL of benzene and 10 mL of 5 N aqueous NaOH
solution was heated at 80 °C with vigorous stirring for 140 h under
nitrogen atmosphere. The mixture was diluted with water and extracted
with CHCl3. The extract was washed with 6 N HCl, water, and saturated
NaCl solution and was dried (MgSO4). After removal of the solvent
the products were separated by flash chromatography followed by
preparative HPLC purification to afford 18 mg (1%) of trimer 12 as a
dark red solid, 183 mg (11%) of tetramer 13 as a dark violet solid, and
15 mg (1%) of pentamer 14 as a reddish orange solid.
Oxidative Coupling of Diethynylpropellatriene 17c Using Cu-
(I)-Cu(II) Salts. To a solution of 400 mg (0.771 mmol) of diyne 17d
in 18 mL of THF was added dropwise 2.0 mL of 1.0 M Bu4NF in
THF (2.0 mmol). The mixture was stirred at room temperature for 1.5
h, diluted with water, and extracted with hexane. The extract was
washed with saturated NaCl solution, dried (MgSO4), and passed
through a column of silica gel. The solvent was removed, and the
residue (17c) was diluted with 20 mL of pyridine. This solution was
added dropwise during a 2 h-period to a solution of 1.40 g (7.71 mmol)
of Cu(OAc)2 and 380 mg (3.84 mmol) of CuCl in 100 mL of pyridine,
which had been bubbled with nitrogen for 20 min. The mixture was
stirred at room temperature for 23 h and the solvent was removed under
reduced pressure. The residue was treated as above (CHCl3 used for
extraction) to give 82 mg (56% from 17d) of a mixture of 15 and 16
in a ratio of ca. 1:1.
11-Chloro-12-[1-(3-hydroxy-3-methylbutynyl)][4.3.2]propella-
1,3,11-triene (33a). Reaction of 6.00 g (28.2 mmol) of 27 and 2-methyl-
3-butyn-2-ol (6.20 g, 84.5 mmol) was carried out as described for the
preparation of 17d for 1.5 h at room temperature using 2.00 g (1.73
mmol) of Pd(PPh3)4 and 750 mg (3.94 mmol) of CuI in 25 mL of THF.
The products were separated by flash chromatography to afford 5.10 g
(70%) of 33a and 272 mg (3%) of 17e both as yellow solids. Final
purification was conducted by preparative HPLC.
12 (mixture of two diastereomers with C3ν and Cs symmetry): mp
1
117 °C dec; H NMR (CDCl3) δ 5.77-5.83 (m, 6H), 5.28-5.35 (m,
6H), 1.96-2.06 (m, 3H), 1.50-1.63 (m, 9H), 0.80-0.88 (m, 6H); 13
C
NMR (CDCl3) δ 139.91, 139.89, 139.78*, 139.76 (q), 126.26, 126.19,
126.17, 126.15 (t)*, 122.00, 121.98*, 121.97, 121.94 (t), 93.47, 93.35*,
93.33, 93.30 (q), 54.47, 54.46*, 54.45, 54.41 (q), 32.14, 32.11*, 32.08,
32.06 (s), 18.86, 18.81, 18.77* (s). The signals marked by asterisk are
due to the C3ν isomer, because the intensities of these signals are slightly
larger than those expected from the statistical distribution (1:3) of C3ν
and Cs isomers: IR (KBr) 1250, 1070, 1020, 800, 750 cm-1; UV-vis
(CHCl3) λmax (log ꢀ) 614 (sh, 1.96), 550 (2.23), 509 (2.24), 250 (4.83)
nm; FAB MS m/z (%): 498 (100) [M+], 261 (30) [M+ - 2(C9H10) -
H]; LD-TOF MS see Figure 2.
13 (mixture of four diastereomers with C4ν, Cs, C2ν, and C2h
symmetry): mp 218-221 °C dec; 1H NMR (CDCl3) δ 5.76-5.81 (m,
8H), 5.37-5.44 (m, 8H), 1.68-1.74 (m, 4H), 1.54-1.66 (m, 12H),
0.92-1.01 (m, 8H); 13C NMR (CDCl3) δ 135.65, 135.62, 135.58,
135.54, 135.53, 135.52, 135.51, 135.49* (q), 127.26, 127.25, 127.21,
127.14, 127.01* (t), 121.91, 121.90*, 121.87, 121.86, 121.85, 121.81
(t), 89.98, 89.95, 89.93, 89.92, 89.91, 89.91*, 89.90, 89.88 (q), 54.93,
54.90, 54.88, 54.87* (q), 32.49, 32.47, 32.45 (s), 18.73, 18.69, 18.66,
18.65 (s). Since the signals marked by * are due to the statistically
least feasible C2ν isomer, these signals have apparently low intensi-
ties: UV-vis (CHCl3) λmax (log ꢀ) 502 (2.72), 309 (4.39), 272 (4.30)
nm; FAB MS m/z (%): 664 (100) [M+], 309 (53) [M+ - 3(C9H10) -
H]; LD-TOF MS see Figure 2.
33a: 1H NMR (CDCl3) δ 5.94-5.76 (m, 4H), 2.19 (s, 1H), 2.00-
1.91 (m, 2H), 1.66-1.13 (m, 4H), 1.15 (s, 6H); 13C NMR (CDCl3) δ
133.3 (q), 128.8 (t), 127.5 (t), 125.5 (q), 122.5 (t), 121.6 (t), 98.9 (q),
71.7 (q), 65.4 (q), 59.3 (q), 55.7 (q), 32.1 (s), 31.5 (s), 31.3 (p), 18.4
(s); IR (neat) 3250, 1250, 1240, 1220, 1160, 1010, 960, 940, 900, 890,
750, 700 cm-1; MS m/z 261 (M+). HRMS found, 260.7628. Calcd for
C16H17OCl, 260.7631.
1
17e: mp 130-134 °C; H NMR (CDCl3) δ 5.94-5.84 (m, 4H),
2.71 (s, 2H), 2.02-1.95 (m, 2H), 1.70-1.20 (m, 4H), 1.15 (s, 12H);
13C NMR (CDCl3) δ 131.8 (q), 128.7 (t), 121.6 (t), 99.2 (q), 74.2 (q),
65.6 (q), 55.7 (q), 32.5 (s), 31.3 (p), 18.6 (s); IR (KBr) 3300, 1290,
1160, 1140, 960, 920, 900, 720 cm-1; MS m/z 308 (M+). HRMS found,
308.4211. Calcd for C21H24O2, 308.4204.
14 (mixture of four diastereomers): mp 108 °C dec; 1H NMR
(CDCl3) δ 5.82-5.88 (m, 10H), 5.68-5.65 (m, 10H), 1.84-1.87 (m,
10H), 1.59-1.61 (m, 10H), 1.14-1.22 (m, 10H); 13C NMR (CDCl3) δ
132.99, 132.97, 132.95, 132.92, 132.86, 132.82, 132.80, 132.78 (q),
128.35, 128.33, 128.29, 128.25, 128.21, 128.20, 128.18, 128.16, 128.11
(t), 121.96, 121.94, 121.91, 121.89, 121.85 (t), 88.80, 88.79, 88.77,
88.75, 88.74, 88.73 (q), 56.08, 56.07, 56.06, 56.05, 56.04, 56.03, 56.02
11-Chloro-12-ethynyl[4.3.2]propella-1,3,11-triene (33b). To a
solution of 521 mg (2.00 mmol) of 33a in 45 mL of toluene was added
a solution of 450 mg (8.0 mmol) of KOH in 3 mL of methanol, and
the mixture was heated under reflux under nitrogen atmosphere for 30
min. After cooling, the mixture was diluted with water, and the organic
layer was washed with saturated NaHCO3 solution and NaCl solution
and then dried (MgSO4). The product was purified by flash chroma-
(q), 32.94 (s), 18.74, 18.71, 18.67 (s); IR (KBr) 1100, 870, 760 cm-1
;
1
tography to afford 293 mg (73%) of 33b as a colorless oil. H NMR
UV-vis (CHCl3) λmax (log ꢀ) 345 (4.53), 263 (4.43) nm; FAB MS m/z
(%): 830 (37) [M+], 357 (100) [M+ - 4(C9H10) - H], 240 (65) [M+
- 5(C9H10)]; LD-TOF MS see Figure 2.
(CDCl3) δ 5.96-5.76 (m, 4H), 3.15 (s, 2H), 2.02-1.93 (m, 2H), 1.67-
1.34 (m, 2H), 1.28-1.15 (m, 2H); 13C NMR (CDCl3) δ 132.2 (q), 128.5

CycloreVersion of [4.3.2]Propella-1,3,11-trienes
J. Am. Chem. Soc., Vol. 122, No. 8, 2000 1775
Alternative Method for Preparation of Dehydro[12]annulene 12.
Coupling of 17c (190 mg, 0.99 mmol) and an excess 27 (3.00 g, 14.1
mmol) was carried out as described for the preparation of 17d using
90 mg (0.47 mmol) of CuI, 274 mg (0.24 mmol) of Pd(PPh3)4, and
586 µL (5.9 mmol) of triethylamine in 6 mL of THF. The 2:1 coupling
product 35 (mixture of three diastereomers) was isolated by flash
137.41, 137.40*, 137.39 (q), 129.04, 129.02*, 128.99, 128.98, 128.96*,
128.94 (t), 122.22, 122.20, 122.19, 122.18 *, 122.16, 122.15, 122.14
(t), 95.30, 95.29, 95.26, 95.25 (q), 87.09, 87.07, 87.02, 87.00 (t), 86.36,
86.35, 86.29, 86.28 (q), 84.06, 84.04, 84.03, 84.02 (q), 83.55, 83.54,
83.53, 83.52 (q), 81.99, 81.97, 81.95, 81.94 (q), 81.80, 81.79, 81.70,
81.69 (q), 58.02, 58.01, 57.97, 57.96, 57.88, 57.87, 57.85, 57.84 (q),
34.58, 34.56, 34.54* (s), 19.06 (s). The intensities of the signals marked
by * are approximately twice as much as those of the signals of similar
environment: IR (KBr) 2140, 1270, 1030, 870, 835, 670 cm-1; UV-
vis (CHCl3) λmax (log ꢀ) 580 (2.20), 516 (2.50), 456 (3.77), 429 (4.00),
421 (4.03), 367 (4.71) nm; LD-TOF MS m/z 520 (M+).
1
chromatography as a yellow solid: mp 68-70 °C; H NMR (CDCl3)
δ 5.77-5.95 (m, 12H), 1.96-2.03 (m, 6H), 1.16-1.67 (m, 12H); 13C
NMR (CDCl3) δ 133.03, 133.01, 132.98 (q), 131.91, 131.90, 131.83
(q), 128.83, 128.44 (t), 127.33, 127.31 (t), 125.67 (q), 122.61 (t), 121.85,
121.55 (t), 86.57 (q), 84.94 (q), 59.64 (q), 56.33, 56.31, 56.16 (q), 33.00
(s), 32.28, 31.83 (s), 18.78 (s), 18.50, 18.48 (s); IR (KBr) 2330, 1200,
1080, 1020, 980, 900, 850, 750 cm-1; MS m/z 544 (M+).
39 (mixture of three diastereomers in an approximate ratio of 1:1:
2): dec 90 °C; This compound once decomposed with mild explosion
when it was scratched with a spatula. 1H NMR (CDCl3) δ 7.48-7.43
(m, 4H), 6.37-6.31 (m, 6H), 6.04-5.99 (m, 2H), 2.48-2.38 (m, 2H),
1.7-1.6 (m, 3H), 1.2-1.0 (m, 1H); 13C NMR (CDCl3) δ 146.23, 146.21,
146.20, 146.17 (q), 145.35, 145.32, 145.30, 145.29 (q), 145.13‡, 145.07,
145.05, 145.03, 145.00 (t), 137.67, 137.66*, 137.65 (q), 129.24, 129.18,
129.17, 129.12 (t), 122.24, 122.22, 122.18, 122.16 (t), 96.17, 96.15,
96.13, 96.11 (q), 95.74, 95.73, 95.71, 95.69 (q), 87.59, 87.57†, 87.53,
87.52, 87.51 (q)*, 87.36, 87.33, 87.22*, 87.19, 87.15*, 87.08 (t), 84.51,
84.49*, 84.47 (q), 83.01, 83.00, 82.92, 82.89 (q), 58.29, 58.24, 58.23,
58.20 (q), 34.86*, 34.81, 34.80 (s), 19.17 (s). The intensities of the
Coupling of 35 (440 mg, 0.81 mmol) with 2-methyl-3-butyn-2-ol
(75 mg, 0.89 mmol) was carried out as described for the preparation
of 33a using 15 mg (0.081 mmol) of CuI, 15 mg (0.040 mmol) of
PdCl2(PhCN)2, and 1.38 g (16 mmol) of piperidine in 9 mL of THF to
afford 225 mg (47%) of monosubstitution product 36 and 191 mg (36%)
of disubstitution product 37 both as orange solids.
36 (mixture of three diastereomers): mp 97-100 °C; 1H NMR
(CDCl3) δ 5.76-5.95 (m, 12H), 2.12 (s, 1H), 1.91-1.99 (m, 6H), 1.64-
1.16 (m including singlet at 1.55, 10H); 13C NMR (CDCl3) δ 133.12,
133.09, 133.07, 133.03, 132.98, 132.97 (q), 132.62, 132.60, 132.57
(q), 131.87, 131.85, 131.81 (q), 128.73, 128.71, 128.67, 128.63, 128.57,
128.47, 128.45 (t), 127.29 (t), 125.66 (q), 122.64, 122.59 (t), 121.83,
121.81, 121.68, 121.64, 121.61 (t), 100.31 (q), 87.63, 87.61, 87.60,
87.58 (q), 86.92, 86.89 (q), 86.64, 86.63 (q), 84.87, 84.84 (q), 74.62
(q), 65.65 (q), 59.61, 59.38 (q), 56.31, 56.30, 56.16, 56.14, 56.09 (q),
33.00, 32.87, 32.76 (s), 32.28 (s), 31.80, 31.39, 31.36 (p), 18.73, 18.47
(s); IR (KBr) 3400, 2340, 1260, 1160, 1090, 1040, 860, 840, 760, 720
cm-1; MS: m/z 593 (M+).
†
‡
signals marked by *, , and are approximately twice, three, or four
times as much as those of the signals of similar environment,
respectively: IR (KBr) 2140, 1280, 1270, 1030, 870, 860, 830, 740,
710, 670 cm-1; UV-vis (CHCl3) λmax (log ꢀ) 627 (2.04), 550 (2.26),
470 (3.66), 441 (3.97), 433 (4.02), 376 (4.68) nm; LD-TOF MS see
m/z 470 (M+).
40 (mixture of two diastereomers with C3ν and C symmetry in an
s
approximate ratio of 1:3): dec 82 °C; This compound once decomposed
1
37 (mixture of three diastereomers): mp 125-127 °C; H NMR
1
with mild explosion when it was scratched with a spatula. H NMR
(CDCl3) δ 5.88-5.78 (m, 12H), 2.75 (s, 2H), 2.00-1.93 (m, 6H), 1.61-
1.17 (m including singlet at 1.55, 24H); 13C NMR (CDCl3) δ 133.15,
133.14, 133.11, 133.08 (q), 132.69, 132.67, 132.65, 132.63 (q), 131.66,
131.65 (q), 128.71, 128.51, 128.45 (t), 121.74, 121.67 (t), 100.54 (q),
87.55, 87.53 (q), 86.91, 86.89, 86.86 (q), 74.47, 74.45 (q), 65.70, 65.51
(q), 56.27 (q), 56.01 (q), 32.94, 32.78, 32.72 (s), 31.32, 31.30 (p), 18.64
(s); IR (KBr) 3350, 2340, 1260, 1160, 1080, 1050, 950, 910, 870, 860,
760, 720 cm-1; MS: m/z 653 (M+).
(CDCl3) δ 7.55-7.50 (m, 6H), 6.52-6.49 (m, 6H); 13C NMR (CDCl3)
δ 145.46, 145.45, 145.39, 145.38 (t), 145.24, 145.22, 145.20, 145.16
(q), 97.02, 97.01, 96.99, 96.98 (q), 89.36, 89.35, 89.33, 89.31 (q), 87.51,
87.44, 87.36, 87.29 (t): IR (KBr) 2120, 1280, 1270, 1030, 880, 865,
830, 710 cm-1; UV-vis (CHCl3) λmax (log ꢀ) 672 (2.01), 583 (2.26),
453 (4.11), 441 (4.10), 387 (4.76) nm; LD-TOF MS m/z 520 (M+)
(see Figure 4).
Photolysis of Dehydro[20]annulene 13 in Furan. A solution of
180 mg (0.270 mmol) of 13 in 20 mL of furan was irradiated with a
low-pressure mercury lamp in a quartz tube for 32 h. The products
were separated by flash chromatography to afford 46 mg (25%) of
unreacted starting material 13 and 37 mg (31%) of monosubstitution
product 42 (a mixture of diastereomers) as an orange solid: mp 122
Intramolecular coupling of 36 was carried out as described for the
preparation of 12-14 using 105 mg (0.18 mmol) of 36, 17 mg (0.089
mmol) of CuI, 102 mg (0.089 mmol) of Pd(PPh3)4, 8.0 mg (0.0035
mmol) of benzyltriethylammonium chloride in 20 mL of benzene and
900 µL of 5 N aqueous NaOH solution for 4 h. Flash chromatography
followed by preparative HPLC gave 14 mg (16%) of trimer 12 which
was identical with a sample prepared by coupling of 33a.
1
°C dec; H NMR (CDCl3) δ 6.84-6.80 (m, 2H), 5.85-5.75 (m, 6H),
5.45-5.34 (m, 6H), 4.69-4.66 (m, 2H), 1.91-1.49 (m, 12H), 1.05-
0.85 (m, 6H); 13C NMR (CDCl3) δ 143.55, 143.50, 143.49, 143.47,
143.43, 143.40 (q), 140.95, 140.93, 140.86, 140.78, 140.76, 140.74
(t), 136.21, 136.17, 136.14, 136.11, 136.08, 136.06, 136.03 (q), 135.61,
135.57, 135.55, 135.34 (q), 127.15, 127.09, 127.04, 126.98, 126.95,
126.91, 126.86, 126.84, 126.81 (t), 122.03, 121.99, 121.95, 121.91,
121.89, 121.87, 121.84, 121.81 (t), 102.06, 102.05, 102.02 (q), 91.48,
91.45, 91.44, 91.37 (q), 90.49, 90.45, 90.42, 90.40, 90.36, 90.34, 90.32,
90.29 (q), 85.75, 85.72, 85.70, 85.69, 85.67, 85.65 (t), 55.00, 54.98,
54.96, 54.92, 54.89, 54.85, 54.84, 54.82, 54.81, 54.78, 54.75 (q), 32.44,
34.42, 32.40, 32.38, 32.35 (s), 18.70, 18.66 (s).
Photolysis of Dehydro[18]annulene 15 in THF-d8. A solution of
10 mg (0.018 mmol) of 15 in 0.8 mL of THF-d8 was irradiated at room
temperature under nitrogen with a low-pressure mercury lamp for 43
h. The progress of the reaction was monitored by H NMR, which
showed gradual formation of indane. Brown films of polymeric material
were formed on the wall of a NMR tube.
1
Photolysis of Dehydro[18]annulene 15 in Furan. A solution of
19 mg (0.033 mmol) of 15 in 40 mL of furan was irradiated with a
low-pressure mercury lamp in a quartz tube for 20 h. In a second run,
81 mg (0.14 mmol) of 15 was irradiated similarly. The combined
products were separated by flash chromatography followed by prepara-
tive HPLC to give 38 (yellowish orange solid, 12 mg, 15%), 39 (dark
orange solid, 20 mg, 27%), and 40 (dark orange solid, 7 mg, 11%).
38 (mixture of three diastereomers in an approximate ratio of 1:1:
Acknowledgment. This work was supported by Grants-in-
Aid from the Ministry of Education, Science, Sports and Culture
of Japan. Y.T. thanks to Shin-Etsu Chemicals Co. for a generous
gift of organosilicon reagents.
1
2): dec 102 °C; H NMR (CDCl3) δ 7.38 (br s, 2H), 6.30-6.18 (m,
6H), 6.02-5.96 (m, 4H), 2.41-2.31 (m, 4H), 1.68-1.54 (m, 6H), 1.22-
1.08 (m, 2H); 13C NMR (CDCl3) δ 146.16, 146.14, 146.13, 146.12
(q), 144.81, 144.80, 144.79* (t), 138.12, 138.10, 138.09, 138.08 (q),
JA993314Z