Syntheses and properties of medium-sized metacyclophanediynes

Article abstract of DOI:10.1021/jo970327r

The syntheses of [11]metacyclophane-2,9-diyne (3), [4.4]metacyclophane- 2,12-diyne (4), [4.4]orthometacyclophane-2,12-diyne (5), (Z)- [10]metacyclophane-5-ene-2,8-diyne (6), [10]metacyclophane-2,8-diyne (7), and 5-isopropylidene[9]metacyclophane-2,7-diyne

Full text of DOI:10.1021/jo970327r

J . Org. Chem. 1997, 62, 5821-5829
5821
Syn th eses a n d P r op er ties of Med iu m -Sized Meta cyclop h a n ed iyn es
Matthias Ramming and Rolf Gleiter*
Organisch-Chemisches Institut der Universita¨t Heidelberg, Im Neuenheimer Feld 270,
D-69120 Heidelberg, Germany
Received February 19, 1997X
The syntheses of [11]metacyclophane-2,9-diyne (3), [4.4]metacyclophane-2,12-diyne (4), [4.4]ortho-
metacyclophane-2,12-diyne (5), (Z)-[10]metacyclophane-5-ene-2,8-diyne (6), [10]metacyclophane-
2,8-diyne (7), and 5-isopropylidene[9]metacyclophane-2,7-diyne (8) have been achieved. The systems
could be stabilized by protecting the triple bonds in 3-8 with the Co2(CO)6 moiety. PE spectroscopic
investigations of 3 and 6-8 gave no clear-cut evidence for homoconjugative interactions among
the π fragments. The triple bonds in 3-8 could be transformed into the corresponding cis double
bonds by applying 2-5 molar equiv of Schwartz’s reagent (28). Treatment of 3, 4, and 7 with
t-BuOK allows the transformation of the propargylic moieties into allenic moieties, whereas the
same treatment of 5 and 6 transforms the 2-butynyl bridges into 1,3-butadiene bridges, giving rise
to several isomers. The structural assignments of 3-8 and their reaction products are based on
their spectroscopic properties.
[n]Metacyclophanes have been known for nearly 20
years.1 The ones with short chains (n ) 4-6) have
attracted the attention of chemists as model compounds
to test the limits of bending aromatic rings.2 Another
aspect arises from [n]metacyclophanes in which the chain
contains heteroatoms such as oxygen and sulfur. These
species enable the complexation of a metal atom such as
magnesium or zinc at the 2-position of the aromatic ring.3
Our interest in this field stems from investigations of
cyclic diynes in which two double bonds were part of the
ring systems.4 Examples are (Z,Z)-4,10-cyclododecadi-
ene-1,7-diyne (1) and 4,9-dimethylene-1,6-cyclodecadiyne
(2). Both systems showed a considerable homoconjuga-
Syn th eses of th e Meta cyclop h a n es 3-8
There are two paths in which the metacyclophanediynes
3-8 can be prepared by reacting a dihalogen compound
with the dilithium salt of a dialkyne as shown in Scheme
1. With the exception of 10 all open-chain dialkynes
needed for path A are described in the literature.4-9 They
can be prepared by reacting the corresponding R,ω-
dihalogen compounds 15-20 with the lithium acetylide-
ethylenediamine complex (9, 13)5,6 or acetylenemagne-
sium chloride (21)4,10 (11,7 12,8,9 144). With the exception
of 11, which can be isolated in only 30% yield, the yield
of the other open-chain alkynes varies from 60% to 80%.
The unknown compound 10 can be obtained in a similar
manner from R,R′-dichloro-m-xylene (16a , Hal ) Cl) and
acetylenemagnesium chloride (21) in 24% yield. Also for
path B the preparations of the halogen compounds, which
could not be purchased, are described in the litera-
ture.11,12 We preferred path A because the dialkynes
9-14 are available in good yields and R,R′-diiodo-m-
tion between the double and triple bonds, and their
reactivity differed as compared to the parent systems.4
These studies led us to conceive systems in which a
benzene ring is part of the chain. In this paper we report
the syntheses of [11]metacyclophane-2,9-diyne (3),
[4.4]metacyclophane-2,12-diyne (4), [4.4]orthometacyclo-
phane-2,12-diyne (5), (Z)-[10]metacyclophane-5-ene-2,8-
diyne (6), [10]metacyclophane-2,8-diyne (7), and
5-isopropylidene[9]metacyclophane-2,7-diyne (8). To-
gether with the preparation of these compounds we
report their transformation into some hydrogenated
species and into their bis(dicobalt hexacarbonyl) com-
plexes as well as their reactions with strong bases.
X Abstract published in Advance ACS Abstracts, J uly 15, 1997.
(1) Rosenfeld, S. M.; Choe, K. A. In Cyclophanes; Keehn, P. M.,
Rosenfeld, S. M., Eds.; Academic Press: New York, 1983; Vol. I, p 311;
Vo¨gtle, F. Cyclophan Chemie; Teubner: Stuttgart, 1990.
(2) Bickelhaupt, F.; de Wolf, W. H. In Advances in Strain in Organic
Chemistry; Halton, B., Ed.; J AI Press Ltd.: London, 1993; Vol. 3, p
185. Kane, V. V.; de Wolf, W. H.; Bickelhaupt, F. Tetrahedron 1994,
50, 4575.
(5) Smith, W. N.; Beumel, O. F., J r. Synthesis 1974, 441.
(6) Brandsma, L. Preparative Acetylenic Chemistry, 2nd ed.; Elsevi-
er: Amsterdam, 1988.
(3) Markies, P. R.; Nomoto, T.; Akkerman, O. S.; Bickelhaupt, F.;
Smeets, W. J . J .; Spek, A. L. Angew. Chem. 1988, 100, 1143. Markies,
P. R.; Nomoto, T.; Schat, G.; Akkerman, O. S.; Bickelhaupt, F.; Smeets,
W. J . J .; Spek, A. L. Organometallics 1991, 10, 3826. Markies, P. R.;
Schat, G.; Akkerman, O. S.; Bickelhaupt, F.; Smeets, W. J . J .; Spek,
A. L. Organometallics 1991, 10, 3538.
(4) Gleiter, R.; Merger, R.; Nuber, B. J . Am. Chem. Soc. 1992, 114,
8921. Gleiter, R.; Merger, R.; Irngartinger, H. J . Am. Chem. Soc. 1992,
114, 8927.
(7) Bowes, C. M.; Montecalvo, D. F.; Sondheimer, F. Tetrahedron
Lett. 1973, 3181.
(8) Ben-Efraim, D. A.; Sondheimer, F. Tetrahedron Lett. 1963, 313.
(9) Mu¨ller, P.; Rodriguez, D. Helv. Chim. Acta 1985, 68, 975.
(10) J ones, E. R. H.; Skattebo¨l, L.; Whiting, M. C. J . Chem. Soc.
1956, 4765.
(11) Marshall, J . A.; Warne, T. M., J r. J . Org. Chem. 1971, 36, 178.
(12) Pre´vost, C.; Valette, A. Compt. Rend. 1946, 222, 326. Valette,
A. Ann. Chim. 1948, 3, 644.
S0022-3263(97)00327-7 CCC: $14.00 © 1997 American Chemical Society

5822 J . Org. Chem., Vol. 62, No. 17, 1997
Ramming and Gleiter
Scheme 2).14 Both values for ∆Gq are in the same order
of magnitude as reported for [7]metacyclophanes.15 The
13C NMR data obtained for the sp carbons in 3, 4, and 6
show no indication for a bending of the triple bonds,
whereas the 13C NMR signals of the acetylenic carbons
in â-position to the aromatic ring of 5, 7, and 8 are
slightly shifted downfield, indicating a deviation of the
triple bond from linearity. Corresponding to this feature
are the AM1 calculations,16 which show angles of 174°
(5), 176° (7), and 173° (8) for the angle C1-C2-C3 (see
8). On the other hand the angle C2-C3-C4 is close to
180° in all metacyclophanediynes. This is also in agree-
ment with the 13C NMR data of 3-8, which all show
signals between δ ) 78 and 80 for the acetylenic carbon
in γ-position to the aromatic ring. The UV data reported
in the Experimental Section indicate that the benzene
rings in 3-8 should be planar. In line with these findings
are calculations using semiempirical methods (AM1,16
MNDO17).
Sch em e 1
Sch em e 2
xylene (16b, Hal ) I) can be prepared easily.13 For path
B, however, only the dibromo compounds of 18 and 20
are available. Former investigations have shown, how-
ever, that diiodo compounds achieve better yields during
cyclization reactions. Furthermore 1,3-dipropargylben-
zene (10), needed for path B in high amounts, can only
be prepared in relatively low yields. In a high-dilution
apparatus the R,ω-diynes are treated at -78 °C with
n-butyllithium to form the dilithium salts 9a -14a
(Scheme 1). Subsequently R,R′-diiodo-m-xylene (16b)
was added to yield 3-8. The reaction time is 2-4 days
with the exception of the preparation of 5 and 8, which
were 7 and 10 days, respectively. The yields obtained
according to path A in Scheme 1 varied from 7% (5) to
24% (3, 7). The reason for the low yields we ascribe to
the high acidity of the benzylic/propargylic protons which
rearrange to form an allenic system (see below) which
polymerizes easily.
Characteristic for all the metacyclophanes is the
chemical shift of the inside-oriented proton at the ben-
zene ring. Its signal is found at δ ) 8.1-8.7. Responsible
for the downfield shift of the inner proton is the aniso-
tropy of the triple bond. We encounter an especially
strong downfield shift in the case of 5, 6, and 8. The most
1
significant signals of the H NMR spectra are collected
To characterize the cyclic diynes further we reacted
them with dicobalt octacarbonyl to obtain the bis(dicobalt
hexacarbonyl) complexes 22-27 which are stable at room
temperature and allow a characterization by elemental
analysis (see Scheme 2). With the exception of 23 we
were able to grow single crystals which allowed the X-ray
investigation. The structures of the bis(dicobalt hexa-
carbonyl) complexes 22 and 24-27 show the anticipated
characteristic features: the triple bonds are bend to 139-
149° and the distances between the bond sp centers
amount to 1.29-1.34 Å.
in Table 1. It is of interest that for the parent [10]meta-
1
cyclophane no temperature dependence of the H NMR
spectrum was found even at low temperatures.15 This
is indicative for low barriers of rotation in the unsubsti-
tuted decamethylene bridge. In 5 and 6, however, the
incorporation of an aromatic ring or a double bond,
respectively, leads to a restriction of the pseudorotation
of the corresponding bridges at low temperatures (-10
°C for 5 and -20 °C for 6). Therefore, for 5 and 6 we
1
observe temperature dependent H NMR spectra, which
allow us to determine the activation parameters (see
P h otoelectr on Sp ectr oscop ic In vestiga tion s
(13) For the preparation of R,R′-diiodo-m-xylene (16b) we used the
method described by Finkelstein, H. Chem. Ber. 1910, 43, 1528, but
using R,R′-dichloro-m-xylene (16a ) instead of the corresponding di-
bromo compound as described in the original literature.
(14) )Binsch, G. Top. Stereochem. 1968, 3, 97. Calder, I. C.; Garratt,
P. J . J . Chem. Soc. B 1967, 660.
To elucidate a possible homoconjugation in 3-8 we
recorded the He I photoelectron (PE) spectra of these
(16) Dewar M. J . S.; Zoebisch, E. G.; Healy E. F.; Stewart, J . J . P.
J . Am. Chem. Soc. 1985, 107, 3902.
(17) Dewar M. J . S.; Thiel, W. J . Am. Chem. Soc. 1977, 99, 4899.
(15) Hirano, S.; Hara, H.; Hiyama, T.; Fujita, S.; Nozaki, H.
Tetrahedron 1975, 31, 2219.

Medium-Sized Metacyclophanediynes
J . Org. Chem., Vol. 62, No. 17, 1997 5823
Ta ble 1. 1H NMR Da ta of th e Meta cyclop h a n ed iyn es 3-8
3
4
5
6
7
8
a
Ar-Hi
Ar-Hr
8.11
7.16-6.99
3.65
8.24
7.19-7.03
3.72
8.49
7.37-6.97
3.58
8.43
7.16-7.00
3.58
8.36
7.17-7.00
3.60
8.69
7.15-7.01
3.56
b
PhsCH2
t-CH2
2.35
3.72
3.71
3.07
2.27
3.05
a
b
Ar-Hi: the inside orientated proton of the aromatic ring. Ar-Hr: aromatic protons with the exception of Hi.
species. In the case of 4 and 5 we were not able to obtain
any spectra due to decomposition upon heating of the
sample. The recorded ionization energies of 3 and 6-8
are listed in Table 2. As an example we show in Figure
1 the PE spectra of 6 and 7. All spectra have two peaks
in common, one centered at 8.6 eV and a second more
intensive one between 9.2 and 9.7 eV. From the areas
below the envelopes of both peaks we assign the first
peak to two and the second one to four (3, 7) or five (6, 8)
transitions. The comparison between the ionization
energies of m-xylene (8.5, 9.0 eV)18 and cyclic diynes such
as 1,7-cyclododecadiyne (9.1, 9.4 eV)19 and 1,8-cyclotet-
radecadiyne (9.1, 9.3 eV)19 allows us to assign the first
peak in all PE spectra to the ionization events from the
two highest π-MOs of the benzene fragment (πar) and the
second peak to the four π-MOs of the triple bonds, arising
from the in plane (πi) and the out of plane (πo) linear
combinations πi-, πi+, πo-, and πo+ (see Table 2). In case
of 6 we assign the shoulder at the low-energy part of the
second peak to the ionization band from the double bond.
gies, ꢀj. The latter were obtained by the AM116 procedure.
Due to the strong overlap of the individual bands it is
difficult to draw any conclusion concerning homoconju-
gation between the different π-units of the systems
investigated. We observe in 6 and 8 a somewhat larger
half-width of the second peak as compared to 3 and 7;
this might be indicative for a homoconjugation of the
double bond and the triple bond in 6 and 8 similar to
(Z,Z)-4,10-cyclododecadiene-1,7-diyne and 4,9-dimethyl-
ene-1,6-cyclodecadiyne.4 Our PE spectroscopic investiga-
tions of 3 and 6-8 reveal no evidence for homoconjuga-
tion between the triple bonds and the aromatic ring
system.
Ta ble 2. F ir st Ver tica l Ion iza tion En er gies, Iv,j, a n d
Ca lcu la ted Or bita l En er gies, Ej, of 3 a n d 6-8 (All Va lu es
Ar e Given in eV)
compd
band
Iv,j
8.5
8.8
9.2
to
assignment -ꢀ (AM116
)
3
1
2
3
4
5
6
19a′′ (πar)
9.30
9.47
10.18
10.21
10.33
10.49
24a′ (πar)
+
23a′ (πo
)
)
)
18a′′ (πi-
}
-
9.5
17a′′ (πo
22a′ (πi+
)
6
1
2
3
4
8.5
8.7 (sh)
9.2
to
9.7
16a′′ (πar)
21a′ (πar)
9.30
9.36
20a′ (πd)
10.10
10.18
10.33
10.35
10.50
-
15a′′ (πo
)
}
+
5
19a′ (πo
)
6
7
14a′′ (πi-
)
9.9
18a′ (πi+
)
7
8
1
2
3
4
5
6
8.6
8.7
9.4
to
(πar)
(πar)
9.24
9.45
10.24
10.27
10.38
10.47
(πi-), (πo
)
-
}
9.5
(πo+), (πi+
)
1
2
3
4
5
8.5
8.6
8.9
9.2
to
20a′′ (πar)
25a′ (πar)
24a′ (πd)
9.27
9.33
9.43
10.10
10.21
10.32
10.58
19a′′ (πi-
)
+
23a′ (πo
18a′′ (πo
)
}
-
6
7
9.5
9.7
)
22a′ (πi+
)
Hyd r ogen a tion Rea ction s
The result of a hydrogenation experiment with 5 using
the Lindlar catalyst21 was disappointing. Treating a
solution of 5 in a petroleum ether/methanol mixture at
50 °C with 80 bar of hydrogen and Lindlar catalyst only
gave very low yields (3-5%) of the dihydrogenated, the
tetrahydrogenated, and the octahydrogenated products.
This result was astonishing in so far as 1,8-cyclotetra-
(18) Klessinger, M. Angew. Chem. 1972, 84, 544; Angew. Chem., Int.
Ed. Engl. 1972, 11, 525.
(19) Gleiter, R.; Karcher, M.; J ahn, R.; Irngartinger, H. Chem. Ber.
1988, 121, 735. Gleiter, R.; Kratz, D.; Scha¨fer, W.; Schehlmann, V. J .
Am. Chem. Soc. 1991, 113, 9258.
F igu r e 1. He I photoelectron spectra of 6 and 7.
Our qualitative assignment is supported by MO results
assuming the validity of Koopmans’ theorem20 which
allows a direct correlation between the recorded vertical
ionization energies, Iv,j, and the calculated orbital ener-
(20) Koopmans, T. Phys. 1934, 1, 104.
(21) Lindlar, H. Helv. Chim. Acta 1952, 35, 446. Dobson, N. A.;
Eglinton, G.; Krishnamurti, M.; Raphael, R. A.; Willis, R. G. Tetrahe-
dron 1961, 16, 16.

5824 J . Org. Chem., Vol. 62, No. 17, 1997
Ramming and Gleiter
Sch em e 5
decadiyne could be hydrogenated to the diene in 77%
yield at atmospheric pressure and room temperature.22
An alternative route to the partially hydrogenated
products was found by applying Cp2Zr(H)Cl, Schwartz’s
reagent (28),23 in benzene at 0 °C as shown in Scheme 3.
By using 2-5 equiv of 28 the yields of 29-34 varied
between 30% and 65%. In the case of the 12- and 13-
membered ring systems, 2-3 equiv of 28 was sufficient;
for the less strained 14-membered ring systems 3 and 4,
4-5 equiv had to be used. Larger amounts of 28 favor
the products in which the triple bonds are reduced to the
alkanes. On the basis of 1H NMR investigations and the
crystal structure of 30, we found only the cis configura-
tion of the newly prepared double bonds in 29-34.
Sch em e 3
Sch em e 4
With the exception of 34 we could not find any
temperature dependence of the signals of the allylic
1
protons down to -60 °C. In the H NMR spectrum of 34
we found at 0 °C a coalescence of the allylic protons
neighbored to the isopropylidene group and at -30 °C
the coalescence of the benzylic protons was found. This
is due to a restricted rotation of the C3 bridge between
the double bonds and the olefinic group itself. In Scheme
4 we show two conformations for 34 which were predicted
close in energy by AM116 and MNDO17 calculations.
Ba se-Ca ta lyzed Isom er iza tion s of 3-8
main product (42%) and 37 (10%) as a side product. All
species have been identified by their spectroscopic prop-
erties. In the 13C NMR spectrum of the first-mentioned
mixture, two sets of ten signals close together, which
differ in intensity, prove the availability of the two
diastereomers 36a and 36b. On the basis of AM1
calculations16 which predict the meso compound 36a to
be more stable than the racemate 36b by 2 kcal/mol, we
assume that the main product has the meso configura-
tion. Our structural assignment of 37 is based both on
In the preceding sections we mentioned the high
reactivity of the benzylic/propargylic hydrogens of 3-8
toward bases. This reactivity was made responsible for
their decomposition in solution. The ease of the isomer-
ization was demonstrated by treating 1,3-dipropargyl-
benzene (10) with t-BuOK in t-BuOH. At 50 °C the
conversion to 1,3-bis(1-propynyl)benzene (35)24 was com-
pleted (Scheme 5) quantitatively after 12 h.
Treatment of 3 with t-BuOK at room temperature
yields the mixture of the bisallenes 36a and 36b as the
1
the H and 13C NMR data. The latter shows two signals
at δ ) 83.4 and 78.6 for the alkyne carbons and three
signals at δ ) 206.2, 94.9, and 94.0 for the allene system.
The treatment of 7 with a surplus of t-BuOK shows
two products from which the minor one (9%) was too
(22) Dale, J .; Hubert, A. J .; King, G. S. D. J . Chem. Soc. 1963, 73.
(23) Hart, D. W.; Blackburn, T. F.; Schwartz, J . J . Am. Chem. Soc.
1975, 97, 679.
(24) Tanaka, Y.; Yamashita, H.; Tanaka, M. Organometallics 1995,
14, 530.

Medium-Sized Metacyclophanediynes
J . Org. Chem., Vol. 62, No. 17, 1997 5825
Sch em e 6
F igu r e 2. 1H NMR spectrum of 43 in CDCl3.
Sch em e 7
The base-induced isomerization of 5 and 6 takes a
different course (Schemes 6 and 7). Treatment of 5 with
t-BuOK at room temperature yields three new com-
pounds. The main product with the lowest Rf value is
assigned to structure 42. This assignment is based on
the observation of two sp carbon signals (δ ) 94.2 and
83.5) and four additional signals in the sp2 region.
Remarkable in the 1H NMR spectrum is a doublet of
doublets at δ ) 8.12. This is due to an “inner” proton of
the butadiene moiety. With the help of a H,H COSY
spectrum we are able to assign the further three protons
of the butadiene moiety at δ ) 6.79, 6.73, and 6.53. The
3J coupling constants of 16.1 and 10.9 Hz, respectively,
support a Z,E configuration of the butadiene fragment.
On the basis of the spectroscopic properties we are left
with two possibilities, 42 and 45. The AM116 calculations
predict 42 by 15 kcal/mol more stable than 45.
unstable to be characterized fully by spectroscopic means.
We assigned its structure to 38. The main product 39
could be isolated and fully characterized. Common to the
monoalkynes 37 and 39 is a restricted ring inversion of
the aromatic ring at room temperature which leads to
1
doublets of the benzylic protons in both cases in the H
NMR spectra.
We notice that the base-induced rearrangement of 3
leads mainly to the bisallene products 36a and 36b while
7 leads only to the monoallenic metacyclophane. We
ascribe this to the higher strain energy of 38 as compared
to 39. In 36a and 36b the longer chain should favor the
bisallene compounds over 37. In line with these argu-
ments are the results of AM116 calculations of 36-39,
predicting the meso compound 36a to be more stable than
37 by 2 kcal/mol. In the case of 38 and 39, the latter is
predicted by 4 kcal/mol to be more stable than 38.
The treatment of 4 with t-BuOK yields a mixture of
two products which could not be separated by column
chromatography or by HPLC. The 13C and 1H NMR
spectra of the mixture could be recorded in CS2. The
analysis of the NMR spectra shows the existence of two
compounds with two allenic moieties in each (δ ) 206.3,
96.4, 95.3 and 206.4, 95.6 and 94.5, respectively). The
data obtained are compatible with 40 (Ci) and 41 (Cs) in
the ratio of 2:3. This assignment is further supported
by the observation of three singlets in the downfield
The isomer with the next higher Rf value is formed in
only 11% yield. The H NMR spectrum of this species
1
(43) is shown in Figure 2. In this spectrum the signals
of the four protons at the butadiene moiety are seen
between δ ) 6.4 and 6.9 as two doublets and two doublets
of doublets. The 3J coupling constants support a Z,E
configuration of the butadiene moiety. As in the case of
42 there is another isomer (46) possible. AM116 calcula-
tions predict that 43 should be more stable than 46 by
35 kcal/mol.
The structure of the isomer with the highest Rf value,
which is formed in only 1% yield, can be assigned to
1
structure 44. As in the case of 43 we expect in the H
NMR spectrum of 44 two doublets for the protons in the
neighborhood of the aromatic rings and two doublets of
doublets for the protons at the 2,3 positions of the
butadiene moieties. One of the doublets is recognized
at δ ) 6.53 (Figure 3). From the H,H COSY spectrum
we were able to assign the other butadiene protons at δ
3
) 6.19, 6.17, and 5.95. The J coupling constants were
1
region of the H NMR spectrum. The most deshielded
found to be 12.8 Hz as well as 13.6 Hz, respectively.
These values favor a Z more than an E configuration.
The all-cis configuration is further supported by the
failure to detect an out of plane C-H vibration between
signal at δ ) 7.94 can be assigned to the inner proton of
the Ci-symmetrical isomer 40, the two signals at δ ) 7.77
and 7.52 to the Cs-symmetrical bisallene 41.

5826 J . Org. Chem., Vol. 62, No. 17, 1997
Ramming and Gleiter
47, however, we pressume an almost planar arrangement
of the hexatriene moiety, based on UV data.
The different isomerization behavior of the metacyclo-
phanes 5 and 6 as compared to 3 and 7 can be rational-
ized by assuming that in all four cases the first step is
the formation of two allenic systems in conjugation to
the benzene nucleus. In case of 5 and 6 the additional
π-system allows the abstraction of an additional proton
in its R-position. This leads to an irreversible rearrange-
ment, and the thermodynamic more stable butadiene
system(s)25 results. In the case of 4 kinetic reasons might
be responsible for the fact that no butadiene moiety was
found.
Treatment of the isopropylidene compound 8 with
t-BuOK results exclusively in the formation of polymers,
according to the high strain of the allenic intermediate.
Con clu sion
F igu r e 3. 1H NMR spectrum of 44 in CDCl3 (LM stands for
CHCl3).
The incorporation of one or two benzene rings in the
skeleton of a cyclic diyne changes the properties consid-
erably. The hydrogen atoms which share the benzylic
and propargylic positions have a high tendency to tau-
tomerize. Thus allenic and olefinic isomers of the start-
ing diynes can be generated easily in the presence of a
strong base. The presence of one or two aromatic rings
hampers the catalytic hydrogenation by Pd/C. This can
be circumvented by using Schwartz’s reagent.
900 and 1000 cm-1. Such a vibration was detectable in
all butadienes with an E configuration (e.g., 42, 43). The
singlet of the meta-substituted benzene ring, which is
part of the doublet at δ ) 6.74, is shifted toward high
field (δ ) 6.73) as compared to 42 and 43. This is in line
by assuming that the proton is shielded by the ortho-
substituted aromatic ring. This would be the case if the
configuration and conformation of 44 is close to that
shown. Furthermore, this result is supported by AM1
calculations.16
Exp er im en ta l Section
Gen er a l. Moisture sensitive reactions were conducted in
oven-dried (150 °C) glassware in a positive argon atmosphere.
Solvents were distilled and dried under argon before use: THF,
benzene, toluene, and tert-butyl alcohol from sodium, CH2Cl2
from P4O10. n-BuLi was purchased from Merck, R,R′-dichloro-
m-xylene (16a ) from Fluka. t-BuOK from Aldrich was used
for the isomerization reactions of the metacyclophanediynes
and sublimated before use. The acyclic diynes 9,5,6 11,7 12,8,9
13,5,6 and 144 as well as Schwartz’s reagent (28)26 were
prepared according to the literature. Reactions were moni-
tored either by GC or TLC. Column chromatography was
carried out on Merck Kieselgel 60 (230-400 mesh) and
alumina (Aldrich). TLC analyses were performed on precoated
plates SIL G/UV254 and ALOX N/UV254, purchased from
Macherey-Nagel. 1H NMR spectra were determined at 300
MHz and 13C NMR spectra at 75.47 MHz if not otherwise
mentioned by using the solvent as an internal standard.
Assignments were based on COSY and double-resonance
experiments.
m -Dip r op a r gylben zen e (10). To a cooled solution of 276
g (3.25 mol) of acetylenemagnesium chloride (21)4,10 in 3 L of
dry THF were added 6.0 g (60.6 mmol) of CuCl, 4.0 g (26.7
mmol) of NaI, and 70.0 g (0.40 mol) of R,R′-dichloro-m-xylene
(16a ), and the mixture was heated to 60 °C for 7 d with
stirring. For workup it was hydrolyzed at 0 °C by slow
addition to a stirred mixture of 600 mL of concentrated HCl,
2.4 kg of ice, and 600 mL of petroleum ether. The organic layer
was separated, and the aqueous layer was extracted three
times with 300 mL of petroleum ether. The combined organic
layers were washed with 200 mL of diluted HCl and then
treated with 100 mL portions of a solution of N-(2-hydroxy-
ethyl)ethylenediamine-N,N′,N′-triacetate (HEDTA) (400 g of
HEDTA and 80 mL of concentrated HCl in 2 L of water) until
the aqueous layer no longer turned blue. After the solution
was washed with brine twice and dried over MgSO4, the
solvent was evaporated and the residue subjected to fraction-
ated distillation under reduced pressure to afford 10 as a
colorless oil (14.8 g, 24%): bp 60 °C (0.11 mbar); UV (CH2Cl2)
232 nm (lg ꢀ 2.47), 256 (2.56), 262 (2.36), 272 (2.19), 290 (2.19);
UV data of the isomerization products indicate that in
both bis(butadiene) compounds 43 and 44 the butadiene
moieties are not coplanar, whereas in the dieneyne 42
the butadiene moiety is close to planarity.
The base-induced isomerization of 6 depends on the
reaction temperature. The treatment of 6 with 2.6 equiv
of t-BuOK at room temperature yields only one product
which could be isolated in 45% yield. The four signals
at δ ) 98.1 and 82.8 as well as δ ) 32.7 and 23.4 in the
13C NMR spectrum suggest one triple bond and a
hexatriene unit as present in (Z,E,Z)-[10]metacyclo-
phane-1,3,5-trien-8-yne (47). The structural assignment
1
is further confirmed by the analysis of the H NMR and
H,H COSY spectrum of 47. As in the case of 42, the
signal of the proton at C3 is shifted downfield (δ ) 7.98).
Remarkable are furthermore the strong highfield shift
of the 13C signal of C6 (δ ) 108.0) and the downfield shift
of the sp carbon atom (δ ) 98.1). This latter points to a
strong bending of the triple bond.
If the base treatment is carried out at 50 °C with 5
equiv of t-BuOK two further substances, (Z,E,Z,E,Z)-
[10]metacyclophane-1,3,5,7,9-pentaene
(48)
and
(Z,Z,Z,E,Z)-[10]metacyclophane-1,3,5,7,9-pentaene (49),
could be isolated in low yields in addition to 47 which
was the main product (40%) also under these conditions.
In the case of 48 and 49 the NMR data clearly point to
the presence of decapentaene units. The 1H NMR spectra
of 48 and 49 could be assigned on the basis of double-
resonance experiments (48) and the H,H COSY spectrum
(49), respectively. Higher yields of 48 (54%) can be
achieved, if 10 equiv of base is used at 50 °C, whereas
the yield of 49 (6%) stays almost constant under these
conditions.
As in the case of the isomerization products of 5, the
UV data of the pentaenes 48 and 49 indicate that the
decapentaene units are not coplanar. For the trieneyne
(25) Hubert, A. J .; Dale, J . J . Chem. Soc. 1965, 3118.
(26) Buchwald, S. L.; LaMaire S. J .; Nielsen R. B.; Watson B. T.;
King S. M. Tetrahedron Lett. 1987, 3895.

Medium-Sized Metacyclophanediynes
J . Org. Chem., Vol. 62, No. 17, 1997 5827
1H NMR (CDCl3) δ 7.35 (s, 1H), 7.33-7.25 (m, 3H), 3.62 (d, 4J
Gen er a l P r oced u r e for th e P r ep a r a tion of th e Bis(d i-
coba lt h exa ca r bon yl) Com p lexes 22-27. To a solution of
the metacyclophanediyne in dry CH2Cl2 was added 2.2 equiv
of Co2(CO)8. After the solution was stirred overnight at rt,
the solvent was removed and the residue was purified by
column chromatography on neutral alumina containing 6%
water. The complexes were eluted with petroleum ether and
isolated quantitatively. For elemental analysis it was neces-
sary to subject them to further column chromatography on
silica gel using petroleum ether as eluent; considerable
amounts of the complexes decomposed during this purification.
The reported yields refer to the amount of bis(dicobalt hexa-
carbonyl) complexes isolated after the second column chroma-
tography. Crystallization of the complexes 22 and 24-27 in
petroleum ether/ether mixtures yielded dark red single crys-
tals.
Bis(d icob a lt h exa ca r b on yl)[11]m et a cyclop h a n e-2,9-
d iyn e (22) was synthesized from 130 mg (0.58 mmol) of
[11]metacyclophane-2,9-diyne (3) and 448 mg (1.31 mmol) of
Co2(CO)8 in 30 mL of CH2Cl2. 22: yield 312 mg (67%); point
of decomposition 156 °C, red crystals; 1H NMR (CDCl3) δ 7.26-
7.23 (m, 2H), 7.14 (d, 3J ) 7.8 Hz, 2H), 4.20 (s, 4H), 3.01 (t, 3J
) 8.0 Hz, 4H), 1.87 (m, 4H), 1.65 (m, 2H); 13C NMR (CDCl3) δ
199.9, 140.7, 129.1, 128.3, 127.5, 98.3, 96.9, 41.9, 33.8, 29.4,
4
) 2.7 Hz, 4H), 2.21 (t, J ) 2.7 Hz, 2H); 13C NMR (CDCl3) δ
136.5, 128.8, 127.5, 126.3, 81.9, 70.5, 24.7; HRMS m/ z calcd
for C12H10 (M+) 154.0783, found 154.0729.
Gen er a l P r oced u r e for th e Cycliza tion Rea ction s. In
a typical run 30.0 mmol of the acyclic diyne was dissolved in
500 mL of dry THF and cooled to -78 °C whereupon 60.0 mmol
of 1.6 N n-BuLi in n-hexane was added slowly with vigorous
stirring. After 30 min of additional stirring, 33.0 mmol of R,R′-
diiodo-m-xylene (16b )13 was added. After warming up, the
mixture was stirred at rt, until one of the educts could not be
detected any more by GC. For workup the mixture was poured
into concentrated NH4Cl solution. The layers were separated,
and the aqueous layer was extracted several times with
CH2Cl2. After the combined organic layers were washed with
water twice, they were dried over Na2SO4 and the solvent was
evaporated. Column chromatography (SiO2, CCl4) of the
residue gave the crude metacyclophanediyne which was
subjected to further purification by Kugelrohr distillation.
[11]Meta cyclop h a n e-2,9-d iyn e (3) was synthesized from
3.6 g (30.0 mmol) of 1,8-nonadiyne (9)5,6 and 11.8 g (33.0 mmol)
of R,R′-diiodo-m-xylene (16b). 3: reaction time 2 d; yield 1.60
g (24%); bp 140 °C (0.11 mbar), yellow oil; UV (CH2Cl2) 222
1
nm (lg ꢀ 3.73), 254 (3.26), 292 (3.00); H NMR (CDCl3) δ 8.11
26.7. Anal. Calcd for C29H18Co4O12
Found: C, 43.98; H, 2.38.
: C, 43.86; H, 2.28.
(s, 1H), 7.16 (t, 3J ) 7.5 Hz, 1H), 6.99 (d, 3J ) 7.5 Hz, 2H),
3.65 (s, 4H), 2.35 (m, 4H), 1.93 (m, 2H), 1.58 (m, 4H); 13C NMR
(CDCl3) δ 137.8, 127.7, 126.7, 125.8, 82.9, 78.1, 27.8, 27.0, 25.0,
18.6; HRMS m/ z calcd for C17H18 (M+) 222.1408, found
222.1385.
Bis(d icoba lt h exa ca r bon yl)[4.4]m eta cyclop h a n e-2,12-
d iyn e (23) was synthesized from 40 mg (0.16 mmol) of
[4.4]metacyclophane-2,12-diyne (4) and 118 mg (0.35 mmol)
of Co2(CO)8 in 10 mL of CH2Cl2. 4: yield 95 mg (73%); point
of decomposition 169 °C, red crystals; 1H NMR (CDCl3) δ 7.20
(m, 2H), 7.06 (m, 4H), 6.94 (s, 2H), 4.07 (s, 8H); 13C NMR
(CDCl3) δ 199.7, 140.0, 129.9, 128.9, 127.7, 96.3, 41.6. Anal.
Calcd for C32H16Co4O12: C, 46.41; H, 1.95. Found: C, 46.66;
H, 2.22.
[4.4]Metacycloph an e-2,12-diyn e (4) was synthesized from
3.0 g (19.5 mmol) of m-dipropargylbenzene (10) and 7.7 g (21.5
mmol) of R,R′-diiodo-m-xylene (16b). 4: reaction time 3 d;
yield 510 mg (10%); point of decomposition 184 °C, white solid;
UV (CH2Cl2) 230 nm (lg ꢀ 2.94), 256 (2.64), 262 (2.62), 286
1
3
(1.81); H NMR (CD2Cl2) δ 8.24 (s, 2H), 7.19 (t, J ) 7.8 Hz,
Bis(d icoba lt h exa ca r bon yl)[4.4]or th om eta cyclop h a n e-
2,12-d iyn e (24) was synthesized from 100 mg (0.39 mmol) of
[4.4]orthometacyclophane-2,12-diyne (5) and 300 mg (0.88
mmol) of Co2(CO)8 in 20 mL of CH2Cl2. 5: yield 205 mg (64%);
point of decomposition 98 °C, red crystals; 1H NMR (CDCl3) δ
2H), 7.03 (d, J ) 7.8 Hz, 4H), 3.72 (s, 8H); 13C NMR (50.33
3
MHz, CD2Cl2) δ 138.2, 128.3, 127.1, 126.3, 80.4, 25.3; HRMS
m/ z calcd for C20H16 (M+) 256.1252, found 256.1219.
[4.4]Or th om eta cyclop h a n e-2,12-d iyn e (5) was synthe-
sized from 3.0 g (19.5 mmol) of o-dipropargylbenzene (11)7 and
7.7 g (21.5 mmol) of R,R′-diiodo-m-xylene (16b). 5: reaction
time 7 d; yield 350 mg (7%); mp 157 °C, white solid; UV
(CH2Cl2) 230 nm (lg ꢀ 2.99), 246 (2.82), 256 (2.85), 260 (2.86),
268 (2.76); 1H NMR (CDCl3) δ 8.49 (s, 1H), 7.37-7.33 (m, 2H),
7.44 (s, 1H), 7.36-7.16 (m, 7H), 4.28 (s, 4H), 3.69 (s, 4H); 13
C
NMR (CDCl3) δ 199.7, 139.4, 138.1, 130.5, 130.2, 129.8, 127.6,
127.3, 97.9, 94.3, 42.2, 36.7. Anal. Calcd for C32H16Co4O12
C, 46.41; H, 1.95. Found: C, 46.71; H, 2.24.
:
Bis(d icoba lt h exa ca r bon yl)-(Z)-[10]m eta cyclop h a n e-
5-en e-2,8-d iyn e (25) was synthesized from 150 mg (0.73
mmol) of (Z)-[10]metacyclophane-5-ene-2,8-diyne (6) and 616
mg (1.80 mmol) of Co2(CO)8 in 20 mL of CH2Cl2. 25: yield
193 mg (34%); point of decomposition 135 °C, red crystals; 1H
3
3
7.28-7.24 (m, 2H), 7.14 (t, J ) 7.5 Hz, 1H), 6.97 (d, J ) 7.5
Hz, 2H), 3.71 (s, 4H), 3.58 (s, 4H); 13C NMR (CDCl3) δ 136.3,
135.6, 131.1, 128.6, 127.6, 127.3, 125.2, 84.3, 79.8, 24.8, 22.8;
HRMS m/ z calcd for C20H16 (M+) 256.1252, found 256.1217.
3
(Z)-[10]Meta cyclop h a n e-5-en e-2,8-d iyn e (6) was syn-
thesized from 10.4 g (0.10 mol) of (Z)-4-octene-1,7-diyne (12)8,9
and 43.0 g (0.12 mol) of R,R′-diiodo-m-xylene (16b). 6: reaction
time 3 d; yield 2.70 g (13%); mp 101 °C, white solid; UV
(CH2Cl2) 232 nm (lg ꢀ 3.25), 244 (3.17); 1H NMR (CDCl3) δ
8.43 (s, 1H), 7.16 (t, 3J ) 7.4 Hz, 1H), 7.00 (d, 3J ) 7.4 Hz,
2H), 5.73 (m, 2H), 3.58 (s, 4H), 3.07 (s, 4H); 13C NMR (CDCl3)
δ 136.7, 127.6, 127.4, 126.0, 125.3, 83.2, 78.8, 24.5, 16.7; HRMS
m/ z calcd for C16H14 (M+) 206.1096, found 206.1051.
NMR (CDCl3) δ 7.29-7.20 (m, 2H), 7.09 (d, J ) 6.8 Hz, 2H),
3
5.64 (s, 2H), 4.15 (s, 4H), 3.72 (d, J ) 3.1 Hz, 4H); 13C NMR
(CDCl3) δ 199.7, 139.8, 129.4, 128.6, 127.6, 127.1, 96.7, 95.6,
41.6, 33.8. Anal. Calcd for C28H14Co4O12: C, 43.22; H, 1.81.
Found: C, 43.05; H, 1.84.
Bis(d icob a lt h exa ca r b on yl)[10]m et a cyclop h a n e-2,8-
d iyn e (26) was synthesized from 40 mg (0.19 mmol) of
[10]metacyclophane-2,8-diyne (7) and 150 mg (0.44 mmol) of
Co2(CO)8 in 10 mL of CH2Cl2. 26: yield 91 mg (61%); point of
decomposition 125 °C, red crystals; 1H NMR (CDCl3) δ 7.35
(s, 1H), 7.26 (t, 3J ) 7.2 Hz, 1H), 7.15 (d, 3J ) 7.2 Hz, 2H),
4.21 (s, 4H), 2.93 (t, 3J ) 6.4 Hz, 4H), 1.38 (t, 3J ) 6.4 Hz,
4H); 13C NMR (CDCl3) δ 199.9, 139.9, 130.7, 129.0, 127.8, 98.2,
97.0, 42.5, 34.2, 31.1. Anal. Calcd for C28H16Co4O12: C, 43.11;
H, 2.07. Found: C, 43.17; H, 2.24.
[10]Meta cyclop h a n e-2,8-d iyn e (7) was synthesized from
3.0 g (28.3 mmol) of 1,7-octadiyne (13)5,6 and 11.3 g (31.6 mmol)
of R,R′-diiodo-m-xylene (16b). 7: reaction time 3 d; yield 1.39
g (24%); mp 76 °C, white solid; UV (CH2Cl2) 230 nm (lg ꢀ 3.22),
1
254 (3.12); H NMR (CDCl3) δ 8.36 (s, 1H), 7.17 (t, 3J ) 7.6
3
Hz, 1H), 7.00 (d, J ) 7.6 Hz, 2H), 3.60 (s, 4H), 2.27 (s, 4H),
1.90 (t, 3J ) 2.7 Hz, 4H); 13C NMR (CDCl3) δ 137.4, 127.6,
127.3, 125.6, 85.4, 77.9, 28.6, 24.6, 19.0; HRMS m/ z calcd for
C16H16 (M+) 208.1252, found 208.1271.
Bis(d icoba lt h exa ca r bon yl)-5-isop r op ylid en e[9]m eta -
cyclop h a n e-2,7-d iyn e (27) was synthesized from 100 mg
(0.43 mmol) of 5-isopropylidene[9]metacyclophane-2,7-diyne (8)
and 335 mg (0.98 mmol) of Co2(CO)8 in 25 mL of CH2Cl2. 8:
yield 103 mg (30%); point of decomposition 131 °C, red crystals;
1H NMR (CDCl3) δ 7.53 (s, 1H), 7.28 (t, 3J ) 6.9 Hz, 1H), 7.12
5-Isop r op ylid en e[9]m eta cyclop h a n e-2,7-d iyn e (8) was
synthesized from 7.5 g (56.7 mmol) of 4-isopropylidene-1,6-
heptadiyne (14)4 and 22.4 g (62.6 mmol) of R,R′-diiodo-m-xylene
(16b). 8: reaction time 10 d; yield 1.36 g (10%); mp 85 °C,
white solid; UV (CH2Cl2) 218 nm (lg ꢀ 2.97), 230 (3.26), 242
(3.18), 246 (3.16); 1H NMR (CDCl3) δ 8.69 (s, 1H), 7.15 (t, 3J )
7.4 Hz, 1H), 7.01 (d, 3J ) 7.4 Hz, 2H), 3.56 (s, 4H), 3.05 (s,
4H), 1.78 (s, 6H); 13C NMR (CDCl3) δ 136.7, 132.1, 129.7, 127.1,
125.1, 124.6, 85.0, 79.2, 24.8, 21.5 (one signal missing); HRMS
m/ z calcd for C18H18 (M+) 234.1409, found 234.1403.
3
(d, J ) 6.9 Hz, 2H), 4.29 (s, 4H), 3.26 (br s, 4H), 1.77 (s, 6H);
13C NMR (CDCl3) δ 199.8, 139.2, 131.8, 131.1, 130.5, 129.4,
126.5, 98.3, 95.3, 42.7, 34.8, 20.9. Anal. Calcd for C30H18
Co4O12: C, 44.70; H, 2.25. Found: C, 44.61; H, 2.42.
-
(Z,Z)-[11]Meta cyclop h a n e-2,9-d ien e (29). To a solution
of 222 mg (1.0 mmol) of [11]metacyclophane-2,9-diyne (3) in
25 mL of dry toluene was added 1.30 g (5.0 mmol) of Schwartz’s

5828 J . Org. Chem., Vol. 62, No. 17, 1997
Ramming and Gleiter
reagent (28) at once. The reaction was monitored by TLC.
After 4 d 3 could not be detected any more and the solution
was cooled to 0 °C. Subsequently 3.0 mL (6.0 mmol) of 2 N
HCl was added at once and the mixture was stirred for
additional 10 min. The suspension was filtered, and the
residue was washed several times with CH2Cl2. The filtrate
was dried over Na2SO4 and the solvent evaporated in vacuo.
Crude 29 could be isolated by column chromatography (SiO2,
petroleum ether). Further purification by Kugelrohr distilla-
tion yielded pure 29 as a colorless oil: yield 76 mg (34%); bp
δ 141.8, 132.5, 129.5, 128.7, 127.6, 125.4, 33.8, 26.8, 26.5;
HRMS m/ z calcd for C16H20 (M+) 212.1565, found 212.1550.
5-Isop r op ylid en e-(Z,Z)-[9]m et a cyclop h a n e-2,7-d ien e
(34). The reaction procedure was the same as that described
for 29, using 222 mg (0.95 mmol) of 5-isopropylidene[9]-
metacyclophane-2,7-diyne (8) in 25 mL of dry toluene and 540
mg (2.1 mmol) of Schwartz’s reagent (28). Reaction time was
20 h. The mixture was quenched by 1.5 mL (3.0 mmol) of HCl.
Pure 34 could be isolated by column chromatography (SiO2,
CCl4) as a colorless oil: yield 126 mg (56%); 1H NMR (CDCl3)
1
115 °C (0.02 mbar); H NMR (CDCl3) δ 7.24 (t, 3J ) 7.5 Hz,
3
3
δ 7.72 (s, 1H), 7.23 (t, J ) 7.5 Hz, 1H), 7.03 (d, J ) 7.5 Hz,
1H), 7.21 (s, 1H), 7.08 (d, 3J ) 7.5 Hz, 2H), 5.70-5.50 (m, 4H),
3
4
3
2H), 5.72 (dtt, J ) 10.8, 7.3 Hz, J ) 1.7 Hz, 2H), 5.47 (dt, J
) 10.8, 6.9 Hz, 2H), 3.42 (d, 3J ) 7.3 Hz, 4H), 2.71 (d, 3J ) 6.9
Hz, 4H), 1.75 (s, 6H); 13C NMR (CDCl3) δ 139.3, 132.9, 129.5,
128.5, 127.7, 126.5, 125.3, 32.8, 31.7, 20.5 (one signal missing);
HRMS m/ z calcd for C18H22 (M+) 238.1722, found 238.1686.
Gen er a l P r oced u r e for th e Isom er iza tion of th e Meta -
cyclop h a n ed iyn es 3-8 a n d 1,3-Dip r op a r gylben zen e (10)
w ith t-Bu OK. The solution of the diyne in dry THF was
cooled to -78 °C. After addition of t-BuOH and t-BuOK the
mixture was stirred for 1 h at the same temperature and was
then allowed to warm up to rt or was heated to 50 °C (see
below). When the educt could not be detected by TLC any
more, water and CH2Cl2 was added successively. The layers
were separated, and the aqueous layer was extracted several
times with CH2Cl2. After the combined organic layers were
dried over Na2SO4, the solvent was evaporated and the residue
was subjected to column chromatography on SiO2 with petro-
leum ether as eluent.
3
3
3.41 (d, J ) 7.8 Hz, 4H), 2.25 (q, J ) 6.4 Hz, 4H), 1.51 (m,
6H); 13C NMR (CDCl3) δ 140.8, 131.5, 128.5, 128.2, 127.9,
125.9, 33.2, 29.0, 27.9, 26.4; HRMS m/ z calcd for C17H22 (M+)
226.1722, found 226.1713.
(Z,Z)-[4.4]Meta cyclop h a n e-2,12-d ien e (30). The reaction
procedure was the same as that described for 29, using 200
mg (0.78 mmol) of [4.4]metacyclophane-2,12-diyne (4) in 10
mL of dry benzene and 800 mg (3.1 mmol) of Schwartz’s
reagent (28). Reaction time was 12 h. The mixture was
quenched by 1.6 mL (3.2 mmol) of HCl. Crude 30 could be
isolated by column chromatography (SiO2, CCl4). Further
purification by Kugelrohr distillation yielded 30 as a white
solid at 145 °C (0.04 mbar). After crystallization in petroleum
ether/ether at 0 °C a colorless single crystal could be isolated:
yield 88 mg (43%); mp 148 °C; 1H NMR (CDCl3) δ 7.43 (s, 2H),
3
3
3
7.23 (t, J ) 7.4 Hz, 2H), 7.08 (d, J ) 7.4 Hz, 4H), 5.67 (t, J
) 6.0 Hz, 4H), 3.47 (d, J ) 6.0 Hz, 8H); 13C NMR (CDCl3) δ
3
140.4, 129.3, 129.1, 128.5, 126.2, 33.2; HRMS m/ z calcd for
Isom er iza tion of [11]Meta cyclop h a n e-2,9-d iyn e (3). A
solution of 100 mg (0.45 mmol) of 3 in 25 mL of THF was
treated with 135 mg (1.2 mmol) of t-BuOK and 165 mg of
t-BuOH. Reaction time 12 h at rt. For workup 20 mL of H2O
was used. After column chromatography two fractions could
be isolated. The first contained a mixture of the two stereo-
isomeric bisallenes 36a and (()-36b, the second consisted of
the alleneyne 37. 36a ,b: yield 42 mg (42%); mp 87 °C,
yellowish solid; Rf (SiO2, petroleum ether) 0.25; IR (KBr) 1941
C20H20 (M+) 260.1565, found 260.1566.
(Z,Z)-[4.4]Or th om eta cyclop h a n e-2,12-d ien e (31). The
reaction procedure was the same as that described for 29,
using 200 mg (0.78 mmol) of [4.4]orthometacyclophane-2,12-
diyne (5) in 10 mL of dry benzene and 460 mg (1.8 mmol) of
Schwartz’s reagent (28). Reaction time was 7 h. The mixture
was quenched by 1.4 mL (2.8 mmol) of HCl. Crude 31 could
be isolated by column chromatography (SiO2, CCl4). Further
purification by Kugelrohr distillation yielded 31 as a white,
waxy solid at 115 °C (0.04 mbar): yield 134 mg (66%); mp 39
cm-1 1H NMR (CDCl3) δ 7.96 (s, 1H), 7.23 (t, 3J ) 7.5 Hz,
;
1H), 6.98 (d, 3J ) 7.5 Hz, 2H), 6.08 (m, 2H), 5.45 (m, 2H), 2.52-
1.08 (m, 10H); 13C NMR (CDCl3) δ 206.4, 135.3, 128.9, 125.6,
123.6, 95.2, 93.7, 30.4, 29.8, 28.6 (36a ); 206.6, 135.8, 128.7,
125.6, 124.6, 94.5, 93.6, 31.7, 30.5, 28.1 ((()-36b); HRMS m/ z
calcd for C17H18 (M+) 222.1409, found 222.1419. 37: yield 10
mg (10%); viscous, yellow oil; Rf (SiO2, petroleum ether) 0.11;
1
3
°C; H NMR (CDCl3) δ 7.61 (s, 1H), 7.25 (t, J ) 7.6 Hz, 1H),
3
3
7.18 (s, 4H), 7.07 (d, J ) 7.6 Hz, 2H), 5.74 (dtt, J ) 10.8, 7.5
4
3
Hz, J ) 2.4 Hz, 2H), 5.53 (dt, J ) 10.8, 5.5 Hz, 2H), 3.46 (d,
3J ) 7.5 Hz, 4H), 3.24 (dd, J ) 5.5 Hz, J ) 2.4 Hz, 4H); 13C
NMR (CDCl3) δ 139.9, 138.9, 133.3, 130.3, 128.8, 128.6, 126.8,
126.6, 125.8, 33.6, 31.8; HRMS m/ z calcd for C20H20 (M+)
260.1565, found 260.1536.
3
4
IR (neat) 2196, 1952 cm-1
;
1H NMR (CDCl3) δ 8.02 (s, 1H),
3
3
3
7.18 (t, J ) 7.5 Hz, 1H), 6.99 (d, J ) 7.5 Hz, 1H), 6.94 (d, J
2
) 7.5 Hz, 1H), 6.11 (m, 1H), 5.46 (m, 1H), 3.67 (d, J ) 19.4
(Z,Z,Z)-[10]Meta cyclop h a n e-2,5,8-tr ien e (32). The reac-
tion procedure was the same as that described for 29, using
160 mg (0.78 mmol) of (Z)-[10]metacyclophane-5-ene-2,8-diyne
(6) in 25 mL of dry toluene and 680 mg (2.6 mmol) of
Schwartz’s reagent (28). Reaction time was 4 d. The mixture
was quenched by 1.5 mL (3.0 mmol) of HCl. Pure 32 could be
isolated by column chromatography (SiO2, petroleum ether)
2
Hz, 1H), 3.48 (d, J ) 19.4 Hz, 1H), 2.31-0.83 (m, 10H); 13C
NMR (CDCl3) δ 206.2, 137.9, 135.4, 128.2, 126.1, 125.5, 125.3,
94.9, 94.0, 83.4, 78.6, 29.7, 28.9, 28.3, 27.6, 24.9, 19.0; HRMS
m/ z calcd for C17H18 (M+) 222.1409, found 222.1406.
Isom er iza tion of [4.4]Meta cyclop h a n e-2,12-d iyn e (4).
A solution of 100 mg (0.39 mmol) of 4 in 20 mL of THF was
treated with 105 mg (0.94 mmol) of t-BuOK and 105 mg of
t-BuOH. Reaction time was 12 h at rt. For workup 20 mL of
H2O was used. After column chromatography a mixture of
two isomeres 40 and 41 could be isolated which could neither
be separated by HPLC nor by further column chromatography.
40, 41: yield 50 mg (50%); point of decomposition 135 °C, white
solid; Rf (SiO2, petroleum ether) 0.12; IR (KBr) 1943 cm-1; 1H
NMR (200 MHz, CS2/CD2Cl2) δ 7.94 (s, 2H, C10-H, C20-H),
7.77, 7.52 (s, 1 H each, C10′-H, C20′-H), 7.25-7.16 (m, 2H each,
C7-H, C17-H, C7′-H, C17′-H), 7.08-6.95 (m, 4H each, C6-H,
C8-H, C16-H, C18-H, C6′-H, C8′-H, C16′-H, C18′-H), 6.23-
6.15 (m, 2H each, PhHCdCdCH), 5.67-5.55 (m, 2H each,
PhHCdCdCH), 3.52 (t, 3J ) 12.2 Hz, 4H, C4′-H, C11′-H),
3.37-3.26 (m, 4H, C4-H, C14-H); 13C NMR (50.33 MHz, CS2/
CD2Cl2) δ 206.4, 206.3, 140.7, 140.6, 135.6, 131.6, 129.6, 129.2,
129.0, 128.0, 127.4, 127.0, 126.7, 126.4, 124.1, 96.4, 95.6, 95.3,
94.5, 37.9, 37.7 (one signal missing); HRMS m/ z calcd for
C20H16 (M+) 256.1252, found 256.1262. The reaction was
repeated with a 5-fold excess of t-BuOK at 50 °C, but only
polymers were found.
1
as a colorless oil: yield 55 mg (33%); H NMR (CDCl3) δ 7.40
(s, 1H, C16-Haromat), 7.23 (t, 3J ) 7.4 Hz, 1H, C13-Haromat), 7.04
3
3
(d, J ) 7.4 Hz, 2H, C12-Haromat, C14-Haromat), 5.73 (dtt, J )
4
11.0, 7.2 Hz, J ) 1.8 Hz, 2H, C2-Holefin, C9-Holefin), 5.50 (dtt,
3J ) 11.0, 7.0 Hz, J ) 1.0 Hz, 2H, C3-Holefin, C8-Holefin), 5.37
4
(tt, 3J ) 4.9 Hz, 4J ) 1.1 Hz, 2H, C5-Holefin, C6-Holefin), 3.40 (d,
3J ) 7.2 Hz, 4H, Ph-CH2), 2.70 (t, 3J ) 6.0 Hz, 4H, dCsCH2);
13C NMR (CDCl3) δ 140.1, 131.1, 128.9, 128.7, 127.2, 126.1,
126.0, 33.8, 26.5; HRMS m/ z calcd for C16H18 (M+) 210.1409,
found 210.1392.
(Z,Z)-[10]Meta cyclop h a n e-2,8-d ien e (33). The reaction
procedure was the same as that described for 29, using 200
mg (0.96 mmol) of [10]metacyclophane-2,8-diyne (7) in 25 mL
of dry benzene and 785 mg (3.0 mmol) of Schwartz’s reagent
(28). Reaction time was 44 h. The mixture was quenched by
2.0 mL (4.0 mmol) of HCl. Crude 33 could be isolated by
column chromatography (SiO2, petroleum ether). Further
purification by Kugelrohr distillation yielded 33 as a colorless
oil at 115 °C (0.04 mbar), which solidified when cooled: yield
118 mg (57%); mp 23 °C; 1H NMR (CDCl3) δ 7.34 (s, 1H), 7.21
(t, 3J ) 7.5 Hz, 1H), 7.00 (d, 3J ) 7.5 Hz, 2H), 5.74 (q, 3J ) 8.9
Isom er iza tion of [4.4]Or th om eta cyclop h a n e (5).
A
3
3
Hz, 2H), 5.35 (dt, J ) 10.7, 7.7 Hz, 2H), 3.35 (d, J ) 8.0 Hz,
4H), 2.18 (q, 3J ) 6.2 Hz, 4H), 1.30 (m, 4H); 13C NMR (CDCl3)
solution of 100 mg (0.39 mmol) of 5 in 20 mL of THF was
treated with 105 mg (0.94 mmol) of t-BuOK and 105 mg of

Medium-Sized Metacyclophanediynes
J . Org. Chem., Vol. 62, No. 17, 1997 5829
H), 6.46 (dd, 3J ) 11.2, 6.3 Hz, 2H, C2-H, C9-H), 6.44 (ddd, 3J
Ta ble 3. Rea ction Con d ition s a n d Yield s for th e
Isom er iza tion of 6
4
3
) 16.9, 3.4 Hz, J ) 1.4 Hz, 2H, C4-H, C7-H), 6.15 (dd, J )
3.4 Hz, 4J ) 1.4 Hz, 2H, C5-H, C6-H); 13C NMR (CDCl3) δ
136.2, 131.7, 130.6, 130.3, 130.0, 129.6, 128.3, 127.1, 125.7;
HRMS m/ z calcd for C16H14 (M+) 206.1096, found 206.1106.
49: yellow, waxy solid; Rf (SiO2, petroleum ether) 0.13; UV
yield, %
temp, °C
time, h
t-BuOK/t-BuOH
47
48
49
25
50
50
12
12
24
214 mg
420 mg
820 mg
45
40
28
1
(CH2Cl2) 232 nm (lg ꢀ 3.46), 250 (3.50), 288 (3.36); H NMR
11
54
3
6
(CDCl3) δ 7.47-7.39 (m, 3H), 7.31-7.23 (m, 3-4H), 6.91 (d,
3J ) 11.5 Hz, 1H, C1-H), 6.81-6.67 (2-3H, two signals could
3
3
be assigned: 6.80 (d, J ) 10.9 Hz, 1H, C10-H), 6.71 (t, J )
10.9 Hz, 1H, C9-H)), 6.52-6.40 (2-3H, two signals could be
t-BuOH. Reaction time was 1 h at rt. For workup 20 mL of
H2O was used. After column chromatography the two isomeric
tetraenes 43 and 44 could be isolated as well as the dieneyne
42. 42: yield 49 mg (49%); mp 77 °C, white solid; Rf (SiO2,
petroleum ether) 0.08; IR (CCl4) 992 cm-1; UV (CH2Cl2) 238
3
3
assigned: 6.49 (dd, J ) 11.0, 5.9 Hz, 1H, C4-H), 6.43 (dd, J
3
) 9.6, 5.9 Hz, 1H, C5-H)), 6.17 (dd, J ) 11.5, 3.8 Hz, 1H, C2-
H), 5.90 (dd, 3J ) 11.0, 3.8 Hz, 1H, C3-H); 13C NMR (50.33
MHz, CDCl3) δ 138.5, 136.7, 135.7, 134.9, 133.4, 129.8, 129.5,
129.4, 129.1, 128.8, 127.9, 118.8, 108.9, 107.6 (two signals
missing); HRMS m/ z calcd for C16H14 (M+) 206.1096, found
206.1094.
1
nm (lg ꢀ 4.36), 264 (4.33), 330 (4.13); H NMR (CDCl3) δ 8.12
(dd, 3J ) 16.1, 10.8 Hz, 1H, PhHCdCH), 7.77 (s, 1H, C20-
3
Haromat), 7.51 (d, J ) 7.5 Hz, 1H, Haromat), 7.35-7.14 (m, 6H,
3
Haromat), 6.79 (d, J ) 10.9 Hz, 1H, PhHCdCHHCdCH), 6.73
Isom er iza tion of [10]Meta cyclop h a n e-2,8-d iyn e (7). A
solution of 100 mg (0.48 mmol) of 7 in 25 mL of THF was
treated with 250 mg (2.2 mmol) of t-BuOK and 250 mg of
t-BuOH. Reaction time was 12 h at rt. For workup 20 mL of
H2O was used. After column chromatography two compounds
could be isolated, but one of them (Rf (SiO2, petroleum ether)
0.33) decomposed during 1H NMR analysis. Signals in the
region between δ ) 6.1 and 5.8 indicated that this compound
could have the bisallenic structure 38. The second compound
was assigned to the alleneyne 39: yield 46 mg (46%); yellow,
viscous oil; Rf (SiO2, petroleum ether) 0.22; IR (neat) 2222,
3
3
(d, J ) 16.1 Hz, 1H, PhHCdCH), 6.53 (t, J ) 10.8 Hz, 1H,
PhHCdCHHCdCH), 2.93-2.84 (m, 4H, CH2); 13C NMR (CDCl3)
δ 140.0, 138.2, 137.4, 135.8, 132.1, 131.7, 131.1, 131.0, 130.9,
130.7, 128.3, 127.7, 126.6, 126.5, 120.1, 94.2, 83.5, 33.0, 23.0
(one signal missing); HRMS m/ z calcd for C20H16 (M+) 256.1252,
found 256.1241. 43: yield 11 mg (11%); mp 76 °C, white solid;
Rf (SiO2, petroleum ether) 0.20; IR (CCl4) 977 cm-1; UV
1
(CH2Cl2) 244 nm (lg ꢀ 4.17), 270 (4.12), 322 (3.75); H NMR
(CDCl3) δ 7.72 (s, 1H, C20-Haromat), 7.38-7.33 (m, 3H, o-Ph-H,
3
4
C17-Haromat), 7.27 (dd, J ) 5.8 Hz, J ) 3.4 Hz, 2H, o-Ph-H),
3
3
7.20 (d, J ) 7.1 Hz, 2H, C16-Haromat, C18-Haromat), 6.89 (d, J
1
1937 cm-1; H NMR (CDCl3) δ 8.28 (s, 1H), 7.20 (t, 3J ) 8.2
) 16.2 Hz, 2H, PhHCdCH), 6.77 (d, 3J ) 11.5 Hz, 2H,
3
3
Hz, 1H), 7.00 (d, J ) 8.2 Hz, 1H), 6.97 (d, J ) 8.4 Hz, 1H),
3
PhHCdCHHCdCH), 6.61 (dd, J ) 16.2, 7.6 Hz, 2H, PhHCd
4
2
6.14 (d, J ) 6.3 Hz, 1H), 5.90 (q, J ) 7.5 Hz, 1H), 3.62 (d, J
) 20.4 Hz, 1H), 3.52 (d, 2J ) 20.4 Hz, 1H), 2.49 (m, 2H), 2.13-
1.60 (m, 6H); 13C NMR (CDCl3) δ 207.4, 137.0, 135.0, 128.3,
126.0, 125.4, 124.8, 95.5, 94.6, 85.9, 78.0, 32.0, 27.4, 27.3, 24.5,
19.3; HRMS m/ z calcd for C16H16 (M+) 208.1252, found
208.1209.
CH), 6.45 (dd, 3J ) 11.5, 7.6 Hz, 2H, PhHCdCHHCdCH); 13
C
NMR (CDCl3) δ 137.1, 136.3, 133.6, 131.2, 130.4, 129.5, 129.3,
129.0, 128.0, 127.2, 127.1; HRMS m/ z calcd for C20H16 (M+)
256.1252, found 256.1200. 44: yield 1 mg (1%); mp 87 °C,
white solid; Rf (SiO2, petroleum ether) 0.23; UV (CH2Cl2) 220
1
nm (lg ꢀ 4.02), 242 (4.10), 286 (3.97); H NMR (CDCl3) δ 7.05
Isom er iza tion of m -Dip r op a r gylben zen e (10). A solu-
tion of 154 mg (1.0 mmol) of 10 in 60 mL of THF was treated
with 561 mg (5.0 mmol) of t-BuOK and 561 mg of t-BuOH.
(dd, 3J ) 5.5 Hz, 4J ) 3.3 Hz, 2H, o-Ph-H), 6.85 (t, 3J ) 7.3
Hz, 1H, C17-Haromat), 6.74 (d, 3J ) 7.3 Hz, 2H, C16-Haromat, C18-
3
4
Haromat), 6.73 (s, 1H, C20-Haromat), 6.67 (dd, J ) 5.5 Hz, J )
3
Reaction time was 12 h at 50 °C. For workup 30 mL of H2O
3.3 Hz, 2H, o-Ph-H), 6.53 (d, J ) 12.8 Hz, 2H, PhHCdCH),
was used. After column chromatography 1,3-bis(1-propynyl)-
benzene (35) could be isolated quantitatively as a colorless oil;
bp 85 °C (0.61 mbar) (lit.21 bp 86 °C (0.53 mbar)); Rf (SiO2,
6.19 (dd, 3J ) 12.8, 6.2 Hz, 2H, PhHCdCH), 6.17 (d, 3J ) 13.6
3
Hz, 2H, PhHCdCHHCdCH), 5.95 (dd, J ) 13.6, 6.2 Hz, 2H,
PhHCdCHHCdCH); 13C NMR (CDCl3) δ 137.8, 137.5, 131.4,
130.9, 129.8, 128.0, 126.9, 125.9, 125.7, 124.9, 122.5. Anal.
Calcd for C20H16: C, 93.71; H, 6.29. Found: C, 93.44; H, 6.31.
Isom er iza t ion of (Z)-[10]Met a cyclop h a n e-5-en e-2,8-
d iyn e (6). The isomerization of 6 was carried out in three
different variations, using 150 mg (0.73 mmol) of 6 in 35 mL
of dry THF as starting material. Quenching was achieved with
25 mL of H2O. The other reaction conditions and yields are
summarized in Table 3. 47: mp 35 °C, yellowish solid; Rf
(SiO2, petroleum ether) 0.09; IR (neat) 990 cm-1; UV (CH2Cl2)
1
petroleum ether) 0.13; H NMR (200 MHz, CDCl3) δ 7.33 (s,
1H), 7.23-7.06 (m, 3H), 1.95 (s, 6H). The analytical data
correspond to those described in the literature.21
He I P E sp ectr a . The PE spectra of 3 and 6-8 were
recorded on a Perkin-Elmer PS18 spectrometer. The recording
temperatures were as follows: 3, 40 °C; 6, 95 °C; 7, 45 °C; 8,
70 °C. In the case of 4 and 5 the samples decomposed during
recording. The calibration was performed with Ar (15.76 and
15.94 eV) and Xe (12.13 and 13.44 eV). A resolution of 20 meV
2
258 nm (lg ꢀ 4.20), 344 (3.91); 1H NMR (CDCl3) δ 7.98 (dd, J
3
on the P3/2 Ar line was obtained.
) 15.1, 11.0 Hz, 1H, C3-H), 7.59 (s, 1H, C16-Haromat), 7.30 (t,
3J ) 8.0 Hz, 1H, C13-Haromat), 7.16 (d, 3J ) 8.5 Hz, 1H, Haromat),
7.13 (d, 3J ) 8.0 Hz, 1H, Haromat), 6.76 (d, 3J ) 10.9 Hz, 1H,
C1-H), 6.46 (t, 3J ) 10.9 Hz, 1H, C2-H), 6.25-6.15 (m, 2H,
C4-H, C5-H), 5.57 (dt, 3J ) 11.5, 2.2 Hz, 1H, C6-H), 2.82-
2.72 (m, 4H, CH2); 13C NMR (CDCl3) δ 140.0, 137.3, 134.6,
132.4, 132.2, 130.9, 130.3, 128.3, 127.3, 126.9, 126.2, 108.0,
98.1, 82.8, 32.7, 23.4; HRMS m/ z calcd for C16H14 (M+)
206.1096, found 206.1064. 48: yellow, waxy solid; Rf (SiO2,
petroleum ether) 0.22; IR (neat) 967 cm-1; UV (CH2Cl2) 242
Ack n ow led gm en t . We thank the Deutsche For-
schungsgemeinschaft (SFB 247), the Fonds der
Chemischen Industrie, and the BASF Aktiengesell-
schaft, Ludwigshafen, for financial support.
Su p p or t in g In for m a t ion Ava ila b le: 1H NMR and 13C
NMR spectra of 3, 8, 10, 29-34, 36, 37, 39-43 and 47 (25
pages). This material is contained in libraries on microfiche,
immediately follows this article in the microfilm version of the
journal, and can be ordered from ACS; see any current
masthead page for ordering information.
3
nm (lg ꢀ 4.40), 270 (4.25); 1H NMR (CDCl3) δ 7.36 (t, J ) 7.0
Hz, 1H, C13-Haromat), 7.33 (s, 1H, C16-Haromat), 7.21 (d, 3J )
7.0 Hz, 2H, C12-Haromat, C14-Haromat), 6.71 (d, 3J ) 11.2 Hz,
3
2H, C1-H, C10-H), 6.53 (dd, J ) 16.9, 6.3 Hz, 2H, C3-H, C8-
J O970327R