Medium-sized cyclophanes. Part 53. Synthesis and conformational studies, and photoinduced cyclization of syn-[n.2]metacyclophanenes

Article abstract of DOI:10.1139/v00-110

A series of [n.2]metacyclophanenes (3) and (6) were prepared in good yields by a McMurry cyclization of 1,n-bis(3-acetyl-4-methoxyphenyl)alkanes (2) and 1,3-bis(3-formyl-4-methoxyphenyl)propane (5), respectively. Compounds 3b, 3c exist in the syn-conformation due to the steric repulsion between the methyl groups at the ethano bridge and the methoxy groups at the aromatic rings while compound 6 prefers the anti-conformation typical of [3.2]metacyclophanes. The assignment of syn-conformations has been confirmed by ¹H NMR analyses and X-ray diffraction studies. Photoinduced transannular cyclization of [n.2]metacyclophanenes (3) and (6) in the presence of iodine as an oxidant afforded phenanthrene-anellated polycyclic aromatic hydrocarbons. Apparently, the rate of the photocyclization of anti-6 was found to be much faster than that of syn-3b and almost completed within 1 h. Thus, the different reactivities for the irradiation of syn- and anti-conformer were observed. The reason for the present preference for the formation of trans-dihydrophenanthrene rather than cis-dihydrophenanthrene as the intermediate might be attributable to the more stable chair form transition state than boat one and the conformational fixation to the chair form in the ground and transition state is possible in the anti-conformer.

Full text of DOI:10.1139/v00-110

1089
Medium-sized cyclophanes. Part 53.1 Synthesis
and conformational studies, and photoinduced
cyclization of syn-[n.2]metacyclophanenes
Takehiko Yamato, Koji Fujita, Keigo Futatsuki, and Hirohisa Tsuzuki
Abstract: A series of [n.2]metacyclophanenes (3) and (6) were prepared in good yields by a McMurry cyclization of
1,n-bis(3-acetyl-4-methoxyphenyl)alkanes (2) and 1,3-bis(3-formyl-4-methoxyphenyl)propane (5), respectively.
Compounds 3b, 3c exist in the syn-conformation due to the steric repulsion between the methyl groups at the ethano
bridge and the methoxy groups at the aromatic rings while compound 6 prefers the anti-conformation typical of
1
[3.2]metacyclophanes. The assignment of syn-conformations has been confirmed by H NMR analyses and X-ray
diffraction studies. Photoinduced transannular cyclization of [n.2]metacyclophanenes (3) and (6) in the presence of
iodine as an oxidant afforded phenanthrene-anellated polycyclic aromatic hydrocarbons. Apparently, the rate of the
photocyclization of anti-6 was found to be much faster than that of syn-3b and almost completed within 1 h. Thus, the
different reactivities for the irradiation of syn- and anti-conformer were observed. The reason for the present preference
for the formation of trans-dihydrophenanthrene rather than cis-dihydrophenanthrene as the intermediate might be attrib-
utable to the more stable chair form transition state than boat one and the conformational fixation to the chair form in
the ground and transition state is possible in the anti-conformer.
Key words: cyclophanes, strained molecule, McMurry reaction, C—C coupling, conformation analysis, cyclizations,
photolysis, transannular reactions, transition states.
Résumé : Faisant appel à une réaction de cyclisation de McMurry des 1,n-bis(3-acétyl-4-méthoxyphényl)alcanes (2) et
1,3-bis(3-formyl-4-méthoxyphényl)propane (5) respectivement, on a préparé une série de [n,2]métacyclophanènes (3) et
(6). Les composés 3b et 3c existent dans la conformation syn en raison de la répulsion stérique entre les groupes
méthyles du pont éthano et les groupes méthoxy des noyaux aromatiques alors que le composé 6 adopte la conforma-
tion anti des [3,2]métacyclophanes. L’attribution des conformations syn a été confirmée par des analyses de RMN du
1H et des études de diffraction des rayons X. La cyclisation transannulaire photoinduite des [n,2]métacyclophanènes (3)
et (6) en présence d’iode, utilisé comme antioxydant, conduit à des hydrocarbures aromatiques polycycliques du type
phénanthrène avec annellation. Apparemment, la vitesse de photocyclisation du produit anti-6 est beaucoup plus rapide
que celle du syn-3b et elle est pratiquement complète en une heure. Ainsi, on a pu observer des réactivités différentes
pour l’irradiation des conformères syn et anti. La raison de la formation observée d’une préférence pour la formation
comme intermédiaire du trans-dihydrophénanthrène plutôt que du cis-dihydrophénanthrène pourrait être attribuée à
l’état de transition en forme chaise qui est plus stable que celui en forme bateau ainsi que le fait que la conformation
des états tant fondamental que de transition du conformère anti peut être fixée à la forme chaise.
Mots clés : cyclophanes, molécule tendue, réaction de McMurry, couplage C—C, analyse conformationnelle, photolyse,
réactions transannulaires, états de transition.
[Traduit par la Rédaction] Yamato et al. 1099
Introduction
syn-[2.2]MCP at low temperature by using (arene)chrom-
iumcarbonyl complexation to control the stereochemistry.
Later, Itô and co-workers (4) also isolated and characterized
syn-[2.2]MCP without complexation. However, syn-
[2.2]MCP isomerizes readily to the anti-isomer above 0°C.
On the other hand, Mitchell and Boekelheide (5) and Staab
Although the parent [2.2]metacyclophane (MCP = meta-
cyclophane) was first reported as early as 1899 by Pelligrin
(2), the synthesis of syn-[2.2]MCP was not realized until 85
years later. Mitchell et al. (3) have successfully prepared
Received March 21, 2000. Published on the NRC Research Press website on August 4, 2000.
T. Yamato2, K. Fujita, and K. Futatsuki. Department of Applied Chemistry, Faculty of Science and Engineering, Saga
University, Honjo-machi 1, Saga-shi, Saga 840-8502, Japan.
H. Tsuzuki. Center of Environmental Analysis, Tohwa Institute for Science, Tohwa University, 1-1-1 Chikushigaoka, Minami-ku,
Fukuoka-shi, Fukuoka 815-8510, Japan.
1Part 52. See Ref. 1.
2Author to whom correspondence may be addressed. Telephone: (0952)28-8679. Fax: (0952)28-8591.
e-mail: yamatot@cc.saga-u.ac.jp
Can. J. Chem. 78: 1089–1099 (2000)
© 2000 NRC Canada

1090
Can. J. Chem. Vol. 78, 2000
Scheme 1.
et al. (6) succeeded in synthesizing intraannularly substi-
tuted syn-[2.2]MCPs, respectively. However, reports on syn-
thesis and reactions of syn-[n.2]MCP-ene have not been
published so far.
In cyclophane chemistry, the reductive coupling of car-
bonyl compounds by low-valent titanium, the McMurry re-
action (7), has been used before by Mitchell and Weerawana (8)
to synthesize cyclophanes with glycol units as bridges, by
Tanner and Wennerström (9), and recently by Hopf and
Mlynek (10) and Grützmacher et al. (11) for a cyclization of
suitable dialdehydes to yield unsaturated cyclophanes.
In this paper, we report on the syntheses of syn- and anti-
[n.2]MCP-enes using the low-valent titanium induced
McMurry reaction and photoinduced transannular cyclization
reaction to afford phenanthrene-anellated polycyclic aromatic
hydrocarbons.
Results and discussion
1,2-Bis(4-methoxyphenyl)ethane (1a) has been prepared
according our previous paper (12). The cross coupling reac-
tions (13) of 4-methoxyphenylmagnesium bromide with 1,3-
dibromopropane and 1,4-dibromobutane have been carried
out in the presence of cuprous bromide as a catalyst in a
mixture of hexamethylphosphoric triamide (HMPA) and
tetrahydrofuran at reflux temperature to give the desired 1,3-
bis(4-methoxyphenyl)propane (1b) and 1,4-bis(4-methoxy-
phenyl)butane (1c) in satisfactory yields. Although the
AlCl3–MeNO2-catalyzed acetylation of compound 1a with
acetyl chloride at 20°C led to complete diacylation, a mix-
ture of the desired 1,2-bis(3-acetyl-4-methoxyphenyl)ethane
(2a) and other isomers was obtained. The desired product 2a
was isolated in pure by the fractional recrystallization from
hexane–benzene (1:1) in 29% yield. In contrast, the AlCl3–
MeNO2-catalyzed acetylation of compounds 1b and 1c with
acetic anhydride or acetyl chloride at 20°C led to
regioselective acylation at the meta positions of the 1,n-
diphenylalkanes affording the desired 1,n-bis(3-acetyl-4-
methoxyphenyl)alkanes (2b) and (2c) in good yields.
Fig. 1. Possible conformations of [n.2]metacyclophan-1-enes.
1,2-Bis(3-acetyl-4-methoxyphenyl)ethane (2a) was sub-
jected to reductive coupling by the McMurry reaction (7)
following the Grützmacher’s procedure (11) (Scheme 1). Al-
though none of the desired [2.2]MCP-1-ene (3a) was ob-
served, the dimer 4a was obtained in 19% yield. This finding
seems to be due to the much more strained structure of 3a
than dimer 4a during the formation of the unsaturated C=C
linkage. Although several cyclizations of 2a were attempted
under the various reaction conditions, no formation of the
desired 3a was observed, with only dimer 4a being obtained.
Thus, during the McMurry reaction the intramolecular
cyclization to afford 3a might be quite difficult.
The structure of product dimer 4a was determined on the
basis of its elemental analysis and spectral data. The mass
spectral data for dimer 4a (M+ m/z = 588) strongly supports
cyclic dimeric structure. In the 1H NMR spectrum of
tetramethoxyMCP 4a, methyl protons, methoxy protons,
ArCH2CH2Ar methylene protons, and the ArCH=CHAr
olefinic protons each appear as a singlet at 27°C. This be-
havior indicates that the rate of conformational ring flipping
of macrocycle 4a is faster than the NMR time scale above
this temperature. However, in dimer 4a even at –60°C in
CDCl3–CS2 (1:3) the singlet signal of the ArCH2CH2Ar
ethylene protons and the ArCH=CHAr olefinic protons both
remain unsplit. These observations indicate the flexible
structure of 4a similar to that of the saturated [24]MCP (14)
in spite of the introduction of two additional double bonds
of the ethylene bridge.
Similarly, 1,n-bis(3-acetyl-4-methoxyphenyl)alkanes (2b)
and 2c were subjected to reductive coupling by the McMurry
reaction (Scheme 1). Novel [n.2]MCP-enes (3b) and (3c)
have been prepared in 40% and 69% yields.
[n.2]MCP-enes adopt either a “staircase” anti-conforma-
tion or a syn-conformation with overlaying aromatic rings
(15) (Fig. 1). Depending on the size of the bridges (16) and
on the presence of intraannular substituents (17), the
interconversion between the syn- and anti-conformers occur
1
by ring flipping. H NMR spectrum of 3b showed the dou-
blet of the intraannular proton Hi at δ = 6.95 (J = 2.0 Hz)
apart from at δ = 6.33 and 6.60 of the other two protons at
the aromatic rings. The methyl protons at the bridged double
bond and methoxy protons were observed as a singlet at
δ = 2.18 and 3.59, and the protons of the trimethylene bridge
generate a complicated signal pattern as expected for a rigid
© 2000 NRC Canada

Yamato et al.
1091
Fig. 2. ORTEP drawing of syn-7,13-dimethoxy-10,11-dimethyl-
Scheme 2.
[3.2]MCP-10-ene (syn-3b). Thermal ellipsoids are drawn at the
50% probability level. All hydrogen atoms are omitted for clar-
ity.
syn-[3.2]MCP-10-ene. The protons of the benzylic CH2
group were observed as two multiplets centered at δ = 2.58
and 2.91 which are further split by coupling with the protons
of the central CH2 group. This central CH2 group was also
observed as two multiplets centered at δ = 1.28 and 2.18.
This peak pattern ascribed to six chemically distinct protons
of the propano bridge proves the absence of a syn–syn
interconversion which would exchange HA and HB of each
CH2 group. Interestingly, similar findings were also ob-
served in syn-[4.2]MCP-11-ene (syn-3c) in spite of being ex-
pected to be more flexible structure attributable to the larger
cyclophane ring size. These observations suggest that the in-
troduction of a double dond of the ethylene bridge as well as
the substituents such as methyl groups and methoxy groups
might control the syn- and anti-conformation of [n.2]MCP-
enes (3).
To study the conformation of [n.2]MCP-enes 3 in more
detail, we have investigated the conformation of the corre-
sponding [3.2]MCP-10-ene 6, which was prepared in 28%
yield by the McMurry cyclization of 1,3-bis(3-formyl-4-
methoxyphenyl)propane (5) under the same reaction condi-
tions like syn-3b (Scheme 2).
Interestingly, in contrast to 3, the doublet of Hi at δ = 6.05
1
(J = 2.4 Hz) in the H NMR spectrum of 6 shows clearly
that 6 adopts a staircase anti-conformation as known for
other [3.2]MCP-10-enes (11a, 11b) and [3.2]MCPs (13c, 15,
16). In addition, the protons of the trimethylene bridge give
rise to two multiplets centered at δ = 2.35 and 1.84, respec-
tively, providing a fast interconversion of the two anti con-
formations of 6 by ring flipping. However, as the
temperature of the solution in CDCl3–CS2 (1:3) is decreased,
a single peak of the benzyl protons splits into a pair of dou-
blets below 0°C. The energy barrier to the conformational
ring flipping estimated from the coalescence temperature
(Tc) is 12.4 kcal mol–1. This finding indicates more flexible
structure of 6 than that of syn-3b in spite of the same ring
size.
Usually, the parent [3.2]MCPs in which intraannular sub-
stituents are absent, preferably adopt an anti-conformation
(15, 16). However, in the case of the MCP 3b the syn-con-
formation is induced by substituents at the ethano bridge.
The substituent effect on the preferred conformation (18)
and the different molecule flexibility of 3b and 6 can be at-
tributed to the van der Waals repulsion between the four
methyl groups in 3b. In the anti-conformation of [3.2]MCP-
10-ene (6) the twisted ethano bridge tends to flatten the
staircase structure to release the local strain. However, this
flattening is especially opposed by the two methoxy groups
in the extraannular position 7 and 13 and the two methyl
groups in the bridge position 10 and 11 of 3b. This effect is
absent in the syn-conformation and, as a consequence, 3b fa-
vors this syn-conformation. The conformation of syn-3b and
syn-3c has also been confirmed by X-ray crystallographic
analysis.
Single colorless crystals of the syn-3b and syn-3c suitable
for X-ray crystallography were both obtained by
recrystallization from methanol–chloroform (1:1). The per-
spective ORTEP drawings of the syn-3b and syn-3c are illus-
trated in Figs. 2 and 3, with the atom numbering system.
Both compounds crystallized in the same monoclinic space
group P21/a. The X-ray crystallography clearly reveals that
both conformations of the syn-3b and syn-3c adopt the syn-
form in which two aromatic rings face each other. Two
aromatic rings of the syn-3b and syn-3c, which deviate from
planarity to some extent, locate like an half-open bivalve
© 2000 NRC Canada

1092
Can. J. Chem. Vol. 78, 2000
Fig. 3. ORTEP drawing of syn-8,14-dimethoxy-11,12-dimethyl-
[4.2]MCP-11-ene (syn-3c). Thermal ellipsoids are drawn at the
50% probability level. All hydrogen atoms are omitted for clarity.
adopts unsymmetrically strained structure and the rigid eth-
ylene chain against the flexible methylene chains might loose
the strain. Furthermore, the intramolecular distances of C(3)-
C(16), C(4)-C(15), C(5)-C(14), C(6)-C(13), C(7)-C(12),
C(8)-C(17) are 2.745, 3.688, 4.493, 4.229, 3.318, and 2.764
Å, and the dihedral angle between the C(3)-C(5)-C(6)-C(8)
and C(13)-C(14)-C(16)-C(17) planes is 39.88°. These
clearly show that two aromatic rings in the syn-3b do not
adopt parallel conformation to avoid an electrostatic interac-
tion.
Two aromatic rings in the syn-3c also strain like a boat
shape as well as those in the syn-3b and the carbons, C(4),
C(7), C(13), and C(16) are remote from the C(3)-C(5)-C(6)-
C(8) and C(14)-C(15)-C(17)-C(18) planes. The dihedral an-
gles of the C(3)-C(5)-C(6)-C(8) plane between the C(3)-
C(4)-C(5) and C(6)-C(7)-C(8) planes, and those of the
C(14)-C(15)-C(17)-C(18) plane between the C(15)-C(16)-
C(17) and C(13)-C(14)-C(18) planes are 1.76°, 3.85°, 1.65°,
and 3.99°, respectively. The fact that the dihedral angles on
the side of the methylene chains are somewhat smaller than
the corresponding ones in the syn-3b might be attributed to
the cancel of strain to some extent because of lengthening
the methylene chains.
Interestingly, the intramolecular distances of C(3)-C(17),
C(4)-C(16), C(5)-C(15), C(6)-C(14), C(7)-C(13), and C(8)-
C(18) in the syn-3c are 2.842, 4.060, 5.336, 5.323, 4.135,
and 3.038 Å, which are much longer than those of the corre-
sponding carbons in the syn-3b. The dihedral angle between
the C(3)-C(5)-C(6)-C(8) and C(14)-C(15)-C(17)-C(18)
planes is 59.53°, which is ca. 20° larger than the appropriate
dihedral angle in the syn-3b. These indicate that two aro-
matic rings in the syn-3c might tilt to a greater extent than
those in the syn-3b, since the methylene chain length of the
syn-3c is longer than that of the syn-3b and the rings are
easy to avoid an electronic repulsion.
The substituents effect on the conformation was observed,
for example, in 10,15-dihydro-5H-tribenzo[a,d,g]cyclononene
and its congeners which adopt their stable crown conforma-
1
tion, evidenced, in H NMR spectra, by the characteristic
AX quartet of the methylene bridges (19). Destabilization of
the crown may arise from steric hindrance created either by
geminal substitution of one methylene group (20) or by the
presence of bulky substituents (21) such as a bromine atom
or an allyl group at the aromatic positions ortho to the nine-
membered ring except a methoxy group (21d, 21e).
using the C(3), C(7), C(12), and C(16) and C(3), C(7),
C(13), and C(17) carbons as roots, respectively, to avoid π-
electronic repulsion as shown in the side view of the ORTEP
drawing. Although the double bond lengths between C(1)-
C(2) in the syn-3b and syn-3c are reasonable, 1.332 and
1.354 Å, respectively, these compounds have quite different
conformations of the two aromatic rings due to the different
methylene chain length.
In the syn-3b, two aromatic rings distort like a boat shape
and deviate from planarity to some extent. The C(4), C(7),
C(12), and C(15) carbons are out of the C(3)-C(5)-C(6)-C(8)
and C(13)-C(14)-C(16)-C(17) planes. The dihedral angles of
the C(3)-C(5)-C(6)-C(8) plane between the C(3)-C(4)-C(5)
and C(6)-C(7)-C(8) planes, and those of the C(13)-C(14)-
C(16)-C(17) plane between the C(14)-C(15)-C(16) and
C(12)-C(13)-C(17) planes are 1.77°, 4.52°, 1.53°, and 5.54°,
respectively, showing that the aromatic rings in the syn-3b
In the present system, the similar substituents effect like
10,15-dihydro-5H-tribenzo[a,d,g]cyclononene might be also
observed. To elucidate this, we have converted the methoxy
group in syn-3b to hydroxy group by demethylation of syn-
3b with boron tribromide (22). The desired diol 7b was ob-
tained in 44% yield. Similarly, dihydroxy[4.2]MCP-11-ene
(7c) was obtained in 53% yield. Interestingly, the bridged
double bond was stable in the acidic media quite differnt
from the results obtained from the anti-[2.2]MCP-enes, in
which the transannular cyclization reactions occur to afford
the corresponding 4,5-dihydropyrenes under the acidic con-
ditions (23). Furthermore, no syn- to anti-ring inversion
1
occurred during the demethylation. The H NMR spectra for
syn-7b and syn-7c (in CDCl3) show signals for the hydroxy
groups at δ 5.29 and 5.15, respectively. It is well known that
the stretching vibration of the OH groups at low frequency
© 2000 NRC Canada

Yamato et al.
Table 1. Conformational analysis of [n.2]MCP-enes 3, 6, and [n.2]MCPs 8.
1093
1H NMR (δ)a aromatic protons
Number of
methylene units (n)
c
Compd
Temp (°C)
Hib
Ho
Assignment
3b
3c
6
8b
8c
3
4
3
3
4
27
6.95
6.93
6.05
4.87, 5.24
5.61, 5.92
6.33, 6.60
6.41, 6.64
6.77, 6.97
6.78, 6.97
6.77, 6.90
syn
syn
anti
anti
anti
–40
–40
27
–30
aDetermined in CDCl3 at room temp by using SiMe4 as a reference and expressed in ppm.
bHi refers to internal protons.
cHo refers to outer protons.
and the resonance for the protons of the OH groups at low
Scheme 3.
field can be attributed to the intramolecular hydrogen bond-
ing (13c, 22d, 24; for the circular intramolecular hydrogen
bonding, see ref. (24b–e)). The υOH (3272 cm–1 for syn-7b
and 3344 cm–1 for syn-7c) and δOH values in syn-7b and syn-
7c in which two hydroxy groups are located in neighbouring
positions, show slightly lower frequency IR vibrations and
down-field NMR shifts, which imply that a weak hydrogen
bond might exist. Therefore, it seems to assume that the syn-
conformation of 7 might be due to the intramolecular hydro-
gen bonding. However, in DMSO-d6 or pyridine-d5 solution,
which can disrupt the intramolecular hydrogen bonding, the
1H NMR spectrum of syn-7b at room temperature is almost
identical with that in CDCl3 and no anti-conformer is ob-
served. These findings might be attributable to the similar
destabilization of the anti-conformation in syn-7b arising
from steric hindrance between the hydroxy groups at the
7,13-positions and the methyl groups on the bridged double
bond at 10,11-positions like syn-3b, but not the intramole-
cular hydrogen bonding among the two hydroxy groups.
An attempted hydrogenation of syn-3b in the presence of
Pd-C in ethyl acetate at room temperature led to afford anti-
8b in 60% yield. The desired product syn-8b has not been
obtained. Thus, syn- to anti-ring inversion occurred during
the hydrogenation (22). The same result was obtained in the
case of the hydrogenation of syn-3c to afford anti-8c.
The structures of anti-8b, 8c were assigned on the basis of
1
elemental analyses and spectral data. The H NMR spectral
data of [n.2]MCP-enes 3, 6 and [n.2]MCPs 8 are summa-
rized in Table 1.
Griffin et al. (25) reported the structure of 1,2-
dimethyl[2.2]MCP and assigned the exo-endo-arrangement
(26). We have assigned the 1H NMR signals of 8 in a similar
1
fashion. In the H NMR spectrum of anti-8b in CDCl3 up-
bridged double bond. This assignment is also applied to the
hydrogenation product anti-8c.
field shifts and the different chemical shifts for internal aro-
matic protons at δ 4.87 and 5.24 due to the ring current of
the opposite aromatic ring were observed (27). These data
strongly suggest that the structure of 8b is the anti-con-
former. Furthermore, the two methyl groups show different
chemical shifts at δ 0.95 and 1.68 as a doublet with coupling
constant J = 7.3 Hz. The higher field absorption is attributed
to the exo methyl group and the lower field absorption is at-
tributed to the endo methyl group which is in a strongly
deshielding region of the oxygen atom of the methoxy group
on the aromatic ring. These data strongly support that the
two methyl groups are exo- and endo-arrangement and there-
fore, anti-8b is found to be cis-hydrogen adduct to the
The conformations of syn- and anti-[n.2]MCP-enes 3, 6,
and anti-[n.2]MCP 8, which have been prepared in the pres-
ent work, in solution are studied by using variable tempera-
1
ture H NMR spectroscopy and the results are compiled in
Table 2.
1
The H NMR spectrum of syn-3b and anti-8b in CDCl3 at
room temperature exhibits the split pattern of the protons at
the methylene bridge. In spite of an increase of the tempera
-
ture to 130°C in CDBr3, no change of the spectrum is ob-
served for saturated [3.2]-system anti-8b. However, in the
case of the unsaturated [3.2]-system syn-3b, as the temperature
© 2000 NRC Canada

1094
Can. J. Chem. Vol. 78, 2000
Table 2. The coalescence temperatures and energy barriers of syn- and anti-[n.2]MCP-enes 3, 6, and anti-[n.2]MCP 8.a
∆G (kcal mol–l)
≠
Compd
Number of methylene units (n)
Solvent
Tc (°C)
syn-3b
syn-3c
anti-6
anti-8b
anti-8c
3
4
3
3
4
CDBr3
120
0
0
>130
35
19.0
13.0
12.4
—
CDCl3–CS2
CDCl3–CS2
CDBr3
CDCl3–CS2
14.4
aTc and ∆Gc were determined in CDCl3–CS2 (1:3) or CDBr3 using SiMe4 as reference.
≠
of the solution of the respective compound in CDBr3, is in-
creased, the individual peaks of the benzyl protons merge
and eventually a single peak is observed above 120°C. This
observation indicates that the rate of conformational ring
flipping of syn-3b is faster than the NMR time scale at this
temperature. The energy barrier to the conformational ring
flipping estimated from the coalescence temperature (Tc) is
19.0 kcal mol–1. The energy barriers for [4.2]-systems syn-
3c and anti-8c were also estimated to be 13.0 (Tc = 0°C) and
14.4 (Tc = 35°C) kcal mol–1, respectively. The unsaturated
[3.2]-system syn-3b found to be about 6.0 kcal mol–1 larger
than that for the corresponding [4.2]-system syn-3c. Thus,
the solution conformation of [n.2]MCP-enes is sensitive to
the chain length of the bridges. The ring inversion barriers
blue shift as indicated by the 60 nm shift for the CT-band of
syn-3c due to the decreased transannular π-electron donation
from the noncomplexed benzene ring to the complexed ben-
zene ring. This finding is fairly consistent with the fact that
the distance between two aromatic rings increased by one
methylene bridge increased as previously described in the
X-ray structures of syn-3b and syn-3c.
In the present [3.2]MCPs there are two possible conform-
ers, anti- and syn-conformer. The through-space electronic
interaction could be performed through the intraannular po-
sitions in the former conformer, but through face-to-face
overlapping among the two benzene rings in the latter con-
former (30). Thus, the charge-transfer complex would be
stabilized by two types of the through-space electronic inter-
action, i.e., face-to-face overlapping and intraannular inter-
action with the opposing benzene ring, thus shifting the
charge-transfer absorption band to the red region. The higher
red shift of [3.2]MCP-10-ene (17 nm) are obtained in syn-
conformer rather than in anti-conformer. Therefore, face-to-
face overlapping might be much more favorable to stabilize
the charge-transfer than the intraannular interaction.
In spite of two routes for the photocyclization of stilbenes
such as staircase anti-conformation and “face-to-face over-
lapping” syn-conformation are possible (31), the latter reac-
tion pathway has not been established due to the lack of the
model compounds. Most investigations of the photoconver-
sion of stilbene derivatives to 9,10-dihydrophenanthrenes
have used anti-[2.2]MCP-1-enes (32) and anti-[2.2]MCP-
1,9-dienes (5a). Boekelheide et al. (32) reported the
photocyclization of anti-[2.2]MCP-1-enes in the presence of
oxidants to afford the corresponding phenanthrenes, but lim-
ited to anti-conformation. Later, Mitchell et al. (33) also re-
ported the synthesis of syn-[2.2]MCP-1,9-diene, which
valence isomerized to cis-dihydropyrene, but readily
isomerized to anti-cyclophane systems. Thus, there is sub-
stantial interest in investigating the photocyclization of pres-
ent syn-[n.2]MCP-enes to explore the above reaction
pathways.
1
determined by variable temperature H NMR dramatically
decrease with increasing length of the bridge by one unit.
Lower ring inversion barriers were observed for the unsat-
urated systems than those for saturated systems in spite of
the smaller ring size due to the introduction of an additional
double bond of the ethylene bridge. For example the barrier
for ring inversion in the [4.2]-system decreases the rigidity
of the system by about 1.4 kcal mol–1 in CDCl3. The de-
creased rigidity of syn-[n.2]MCP-enes (3) may be attributed
to the expanded bond angles of the bridged double bond.
Tetracyanoethylene (TCNE) complexes have often been
used in studies on the relative π-base strength of various
methyl-substituted benzenes (28). The π-basicity of the do-
nor molecules increases with an increase in the number of
substituted methyl groups and (or) stacking benzene rings
and an increase in the face-to-face overlapping between aro-
matic nuclei (29). A solution of anti-[3.2]MCP-10-ene (anti-
6) and TCNE in CH2Cl2 present a reddish brown colour and
the charge-transfer band at 508 nm (log ε = 2.329) was ob-
served in its UV spectrum. This absorption is due to the for-
mation of 1:1 charge-transfer complex among the electron
donor, [3.2]MCP, and the electron acceptor, TCNE. The po-
sition of absorption maximum and the shape of absorption
curve remain unchanged when a 4–12-fold excess of TCNE
was added. However, the charge transfer absorption band of
the reference compound, 2,4-dimethylanisole (9) with TCNE
was observed at 414 nm (log ε = 2.073). Such a red shift
could be due to the through space electronic interaction of
the opposite uncomplexed benzene ring, which tends to
work as a π-electron donor.
Actually, when syn-3b was irradiated in the presence of
iodine as an oxidant at room temperature for 1 h, the desired
phenanthrene 10 was obtained only in 23% yield along with
recovery of the starting compound. In contrast, similar reac-
tion of anti-6 carried out under the same reaction conditions
afforded the cyclization product 11 in 90% yield.
In contrast to anti-[3.2]MCP-10-ene (anti-6), which ex-
hibits the charge-transfer absorption band with TCNE at
508 nm (log ε = 2.329), a mixture of TCNE and syn-
[3.2[MCP-10-ene (syn-3b) exhibits an absorption peak at
525 nm (log ε = 2.334), that of syn-[4.2[MCP-11-ene (syn-
3c) is shifted to 466 nm (log ε = 2.001). Introduction of the
one methylene to propane bridge of syn-3b causes a larger
The rate of the photocyclization of anti-6 was found to be
much faster than that of syn-3b and almost completed within
1 h. The different reactivities for the irradiation of syn-3b
and anti-6 were observed. In the present photocyclization re-
action of syn-3b, the photoinduced syn–anti-isomerization
might be possible to afford the corresponding anti-con-
former anti-3b, which is cyclized to the cyclization product
© 2000 NRC Canada

Yamato et al.
1095
Scheme 4.
GC-14A (Silicone OV-1, 2 m, programmed temperature rise,
12°C/min, carrier gas nitrogen, 25 mL/min).
Materials
1,n-Bis(4-methoxyphenyl)alkanes 1 were prepared follow-
ing previous reports (12, 13).
Preparation of 1,n-bis(3-acetyl-4-methoxyphenyl)alkane
(2) — typical procedure
To a solution of 1,3-bis(4-methoxyphenyl)propane (1b)
(3.84 g, 15 mmol) and acetyl chloride (3.15 mL, 45 mmol)
in methylene dichloride (60 mL) was added a solution of
aluminum chloride (8.91 g, 67.5 mmol) in nitromethane
(15 mL) at 0°C. After the reaction mixture had been stirred
at room temperature for 3 h, it was poured into ice water
(100 mL). The organic layer was extracted with CH2Cl2 (2 ×
50 mL). The extract was washed with water (2 × 50 mL),
dried (Na2SO4), and concentrated. The residue was
chromatographed over silica gel (Wako C-300, 300 g) with
CHCl3 as eluent to give crude 2b as a colorless solid.
Recrystallization from hexane–benzene (1:1) gave 1,3-bis(3-
acetyl-4-methoxyphenyl)propane (2b) (4.42 g, 87%) as col-
orless prisms, mp 46–48°C. IR (KBr) υmax: 1667 (C=O) cm–1.
1H NMR (CDCl3) δ: 1.85–1.95 (2 H, m), 2.55–2.62 (4
H, m), 2.60 (6 H, s), 3.89 (6 H, s), 6.90 (2 H, d, J = 8.0),
7.27 (2 H, dd, J = 8.0, 2.0), 7.52 (2 H, d, J = 2.0). MS m/z:
M+ 340. Anal. calcd. for C21H24O4 (340.42): C 74.09, H
7.11; found: C 74.20, H 7.15.
10. In fact, the irradiation of syn-3b in the absence of iodine
as an oxidant at room temperature was attempted, but none
of the formation of anti-conformer anti-3b was observed
under the present reaction conditions. This result indicates
that the cyclization product 10 might be directly formed via
the syn-3b, but not the corresponding anti-3b as an intermedi-
ate.
Examination of molecular models led us to believe that
the transformation of anti-6 into phenanthrene 11 should be
straightforward, since in the conformationally rigid stilbene
moiety of anti-6, the π orbitals involved in the required pho-
tochemically produced disrotatory cyclization leading even-
tually to the phenanthrene 11 are apparently very close in
space. The reason for the present preference for the forma-
tion of trans-dihydrophenanthrene rather than cis-
dihydrophenanthrene as the intermediate might be attribut-
able to the more stable chair form transition state than boat
one and the conformational fixation to the chair form in the
ground and transition state is possible in the anti-conformer.
In conclusion, a new synthesis of syn- and anti-[n.2]MCP-
enes by a McMurry cyclization has been developed and ap-
plied to the synthesis of phenanthrene-anellated polycyclic
aromatic hydrocarbons substituted at positions 4 and 5 by
the successive photoinduced transannular cyclization reac-
tion. Further studies on the present novel photoinduced trans-
annular cyclization reaction of 3 and 6 are now in progress.
Compounds 2a and 2c were similarly prepared in 29 and
71% yields, respectively.
1,2-Bis(3-acetyl-4-methoxyphenyl)ethane (2a)
Colorless prisms (hexane–benzene (1:1)), mp 114–115°C.
1
IR (KBr) υmax: 1664 (C=O) cm–1. H NMR (CDCl3) δ: 2.60
(6 H, s), 2.84 (4 H, s), 3.89 (6 H, s), 6.87 (2 H, d, J = 8.7),
7.23 (2 H, dd, J = 8.7, 2.4), 7.54 (2 H, d, J = 2.4). MS m/z:
M+ 326. Anal. calcd. for C20H22O4 (326.4): C 73.6, H 6.79;
found: C 73.45, H 6.89.
1,4-Bis(3-acetyl-4-methoxyphenyl)butane (2c)
Colorless prisms (hexane–benzene (1:1)), mp 74–76°C. IR
1
(KBr) υmax: 1669 (C=O) cm–1. H NMR (CDCl3) δ: 1.60 (4
H, m), 2.57 (4 H, m), 2.60 (6 H, s), 3.88 (6 H, s), 6.87 (2 H,
d, J = 8.3), 7.25 (2 H, dd, J = 8.7, 2.4), 7.52 (2 H, d, J =
2.4). MS m/z: M+ 354. Anal. calcd. for C22H26O4 (354.5): C
74.55, H 7.39; found: C 74.26, H 7.18.
McMurry coupling reaction of 2 — typical procedure
The McMurry reagent was prepared from TiCl4 [23.8 g
(13.8 mL), 125 mmol] and 18 g (275 mmol) of Zn powder
in 500 mL of dry THF, under nitrogen. A solution of 2b
(3.06 g, 9 mmol) and pyridine (22.5 mL, 200 mmol) in dry
THF (250 mL) was added within 60 h from two Hershberg
funnels to the black mixture of the McMurry reagent by us-
ing a high-dilution technique (34) with continuous refluxing
and stirring. The reaction mixture was refluxed for an addi-
tional 8 h, cooled to room temp., and hydrized with aqueous
10% K2CO3 (200 mL) at 0°C. The reaction mixture was
extracted with CH2Cl2 (3 × 200 mL). The combined extracts
were washed with water, dried with Na2SO4 and concentrated.
Experimental
All melting points (Yanagimoto MP-S1) were uncor-
rected. Proton nuclear magnetic resonance (1H NMR) spec-
tra were recorded on a Nippon Denshi JEOL FT-270
spectrometer. Chemical shifts are reported as δ values (ppm)
relative to internal Me4Si. Mass spectra were obtained on a
Nippon Denshi JMS-01SG-2 mass spectrometer at an ioniza-
tion energy of 70 eV (m/z values reported include the parent
ion peak). Infrared (IR) spectra were obtained on a Nippon
Denshi JIR-AQ2OM spectrophotometer as KBr disks. Ele-
mental analyses were performed by Yanaco MT-5. GLC
analyses were performed by Shimadzu gas chromatograph
© 2000 NRC Canada

1096
Can. J. Chem. Vol. 78, 2000
1
The residue was chromatographed over silica gel (Wako C-
300, 300 g) with benzene as eluents to give crude 3b as a
colorless solid. Recrystallization from benzene gave syn-
7,13-dimethoxy-10,11-dimethyl[3.2]metacyclophan-10-ene
(syn-3b) (1.10 g, 40%) as colorless prisms, mp 162–163°C.
1H NMR (CDCl3) δ: 1.20–1.45 (1 H, m), 2.10–2.25 (1
H, m), 2.18 (6 H, s), 2.50–2.65 (2 H, m), 2.85–2.98 (2
H, m), 3.59 (6 H, s), 6.33 (2 H, d, J = 8.0), 6.60 (2 H, dd,
J = 2.0, 8.0), 6.95 (2 H, d, J = 2.0). MS m/z: M+ 308. Anal.
calcd. for C21H24O2 (308.42): C 81.78, H 7.84; found: C
81.71, H 7.78.
prisms, mp 93–94°C. IR (KBr) υmax: 1682 (C=O) cm–1. H
NMR (CDCl3) δ: 1.88–2.00 (2 H, m), 2.60–2.67 (4 H, m),
3.95 (6 H, s), 6.95 (2 H, d, J = 8.8), 7.39 (2 H, dd, J = 8.8,
2.4), 7.66 (2 H, d, J = 2.4), 10.48 (2 H, s). MS m/z: M+ 312.
Anal. calcd. for C19H20O4 (312.37): C 73.06, H 6.45; found:
C 73.19, H 6.32.
McMurry coupling reaction of 5
The McMurry reagent was prepared from TiCl4 [23.8 g
(13.8 mL), 125 mmol] and 18 g (275 mmol) of Zn powder
in 500 mL of dry THF, under nitrogen. A solution of 5
(3.21 g, 9 mmol) and pyridine (22.5 mL, 200 mmol) in dry
THF (250 mL) was added within 60 h to the black mixture
of the McMurry reagent by using a high-dilution technique
with continuous refluxing and stirring. The reaction mixture
was refluxed for additional 8 h, cooled to room temp, and
hydrized with aqueous 10% K2CO3 (200 mL) at 0°C. The
reaction mixture was extracted with CH2Cl2 (3 × 200 mL).
The combined extracts were washed with water, dried with
Na2SO4, and concentrated. The residue was chromatogra-
phed over silica gel (Wako C-300, 300 g) with hexane–ben-
zene (1:1) as eluents to give crude 6 as a colorless solid.
Recrystallization from methanol gave anti-7,13-dimeth-
oxy[3.2]metacyclophan-10-ene (anti-6) (711 mg, 28%) as
colorless prisms, mp 94–95°C. IR (KBr) υmax: 1593, 1485,
Similarly, the McMurry coupling reaction was carried out
for compounds 2a and 2c in the same manner as described
above.
For 2a the residue was chromatographed over silica gel
(Wako C-300, 300 g) with benzene–CHCl3 (1:1) as eluents
to give crude 4a as a colorless solid. Recrystallization from
CHCl3 gave 4a (500 mg, 19%) as colorless prisms.
For 2c the residue was chromatographed over silica gel
(Wako C-300, 300 g) with hexane–benzene (1:1) as eluents
to give crude syn-3c as a colorless solid. Recrystallization
from hexane gave syn-3c (2.01 g, 69%) as colorless prisms.
4,14,20,30-Tetramethoxy-1,2,17,18-tetramethyl[2.2.2.2]-
metacyclophane-1,17-diene (4a)
1
1461, 1276, 1255, 1242, 1114, 1027, 797, 753 cm–1. H
Colorless prisms (CHCl3), mp 280–282°C. IR (KBr) υmax
:
2930, 1497, 1456, 1262, 1253, 1229, 1133, 1050, 1031,
NMR (CDCl3) δ: 1.78–1.89 (2 H, m), 2.20–2.50 (4 H,
broad s), 3.85 (6 H, s), 6.05 (2 H, d, J = 2.4), 6.77 (2 H, d, J
= 8.3 Hz), 6.88 (2 H, s), 6.97 (2 H, dd, J = 8.3, 2.44). MS
m/z: M+ 308. Anal. calcd. for C19H20O2 (280.37): C 81.4, H
7.19; found: C 81.62, H 7.26.
1
810 cm–1. H NMR (CDCl3) δ: 2.15 (12 H, s), 2.50 (8 H,
broad s), 3.58 (12 H, s), 6.56 (4 H, d, J = 8.3), 6.71–6.80 (4
H, broad s), 6.83 (4 H, dd, J = 8.3, 2.0). MS m/z: M+ 588.
Anal. calcd. for C40H44O4 (588.79): C 81.6, H 7.53; found:
C 81.81, H 7.68.
Demethylation of syn-3b
syn-8,14-Dimethoxy-11,12-dimethyl[4.2]metacyclophan-11-
ene (syn-3c)
To a solution of syn-3b (32.2 mg, 0.105 mmol) in CH2Cl2
(5 mL) at 0°C was gradually added a solution of BBr3
(0.03 mL, 0.3 mmol) in CH2Cl2 (1 mL) over a period of
15 min. After the reaction mixture has been stirred at room
temperature for 2 h, it was poured into ice water (50 mL),
extracted with CH2Cl2 (3 × 20 mL). The combined extracts
were washed with water (2 × 20 mL), dried over Na2SO4,
and concentrated in vacuo to leave a residue. The residue
was recrystallized from hexane–ethyl acetate (1:1) gave syn-
7,13-dihydroxy-10,11-dimethyl[3.2]metacyclophan-10-ene
(syn-7b) (14.1 mg, 44%) as colorless prisms, mp 189–
Colorless prisms (hexane), mp 160–161°C. IR (KBr)
υmax: 2923, 1493, 1442, 1252, 1226, 1032, 805, 797 cm–1.
1H NMR (CDCl3) (27°C) δ: 1.55 (4 H, broad s), 2.14 (6
H, s), 2.36 (4 H, broad s), 3.63 (6 H, s), 6.41 (2 H, d, J =
1
8.3), 6.59 (2 H, dd, J = 2.4, 8.3), 6.90 (2 H, d, J = 2.4). H
NMR (CDCl3) (–40°C) δ: 1.1–1.4 (2 H, broad s), 1.72–1.92
(2 H, broad s), 2.17 (6 H, s), 2.1–2.3 (2 H, broad s), 2.4–2.6
(2 H, broad s), 3.67 (6 H, s), 6.41 (2 H, d, J = 8.3), 6.64 (2
H, dd, J = 2.4, 8.3), 6.93 (2 H, d, J = 2.4). MS m/z: M+ 322.
Anal. calcd. for C22H26O2 (322.45): C 81.95, H 8.13; found:
C 82.07, H 8.15.
189.5°C. IR (KBr) υmax: 3272 (OH) cm–1. H NMR (CDCl3)
1
δ: 2.23 (6 H, s), 2.05–2.28 (2 H, broad s), 2.45–2.62 (2 H,
broad s), 2.78–2.98 (2 H, broad s), 5.29 (2 H, s, replaced by
D2O), 6.33 (2 H, d, J = 8.30), 6.56 (2 H, dd, J = 8.30, 2.44),
6.85 (2 H, d, J = 2.44). MS m/z: M+ 306. Anal. calcd. for
C19H20O2 (280.37): C 81.4, H 7.19; found: C 81.62, H 7.28.
Compound syn-7c was similarly prepared in 53% yield.
Preparation of 1,3-bis(3-formyl-4-methoxyphenyl)-
propane (5)
To a solution of 1,3-bis(4-methoxyphenyl)propane (1b)
(2.24 g, 8.75 mmol) and Cl2CHOCH3 (2.28 mL, 25.2 mmol)
in CH2Cl2 (20 mL) was added a solution of TiCl4 (6.0 mL,
54.5 mmol) in CH2Cl2 (20 mL) at 0°C. After the reaction
mixture was stirred at room temp for 3 h, it was poured into
a large amount of ice water (400 mL) and extracted with
CH2Cl2 (2 × 200 mL). The combined extracts were washed
with water, dried with Na2SO4, and concentrated. The resi-
due was chromatographed over silica gel (Wako C-300,
500 g) with CHCl3 as eluent to give crude 5.
Recrystallization from hexane gave 2.81 g (99.6%) of 1,3-
bis(3-formyl-4-methoxyphenyl)propane (5) as colorless
syn-8,14-Dihydroxy-11,12-dimethyl[4.2]metacyclophan-11-
ene (syn-7c)
Colorless prisms (hexane–ethyl acetate (1:1)), mp 194–
194.5°C. IR (KBr) υmax: 3344 (OH) cm–1. H NMR (CDCl3)
1
δ: 1.40–1.75 (4 H, broad s), 2.19 (6 H, s), 2.20–2.42 (4 H,
broad s), 5.15 (2 H, broad s, replaced by D2O), 6.38 (2 H, d,
J = 8.3), 6.52 (2 H, dd, J = 2.4, 8.3), 6.80 (2 H, d, J = 2.4).
MS m/z: M+ 294. Anal. calcd. for C20H22O2 (294.38): C
81.6, H 7.53; found: C 81.91, H 7.50.
© 2000 NRC Canada

Yamato et al.
Table 3. Crystallographic data and data collection details for syn-10,11-dimethyl-7,13-dimethoxy[3.2]MCP-10-
1097
ene (syn-3b) and syn-11,12-dimethyl-8,14-dimethoxy[4.2]MCP-11-ene (syn-3c).
syn-3b
syn-3c
Formula
Mol. mass
C21H24O2
308.42
C22H26O2
322.45
Crystal size (mm)
0.4 × 0.25 × 0.25
monoclinic
P21/a (no. 14)
4
0.30 × 0.25 × 0.25
monoclinic
P21/a (no. 14)
4
Space group
Z
a (pm)
b (pm)
c (pm)
1924.58 (26)
759.26 (6)
1225. 00 (17)
102.80 (1)
1745.5 (4) × 10–30
1.154
1983.78 (19)
819.66 (6)
1155.81 (13)
98.9677 (85)
1856.4 (3) × 10–30
1.174
β (°)
V (m3)
Dc (gm–3)
Radiation
µ (Cu-Kα) (cm–1)
Cu-Kα
5.4
Cu-Kα
5.29
Total no. of unique reflections
3142
3365
R
0.117
0.067
Rw
0.091
0.107
(200 mL) in a Pyrex flask and then irradiated by a 400 W
high-pressure mercury lamp while being monitored by GLC.
Irradiation was continued until the disappearance of the re-
actant anti-6 (1 h). The reaction mixture was washed with
10% sodium thiosulfate and water, dried with Na2SO4, and
concentrated. The residue was chromatographed over silica
gel (Wako C-300, 100 g) with hexane–benzene (1:1) as elu-
ents to give 11 (100 mg, 90%) as a colorless solid.
Recrystallization from hexane gave 1,8-dimethoxy-4,5-
propanophenanthrene (11) as colorless prisms, mp 86–87°C.
IR (KBr) υmax: 2937, 1587, 1498, 1426, 1270, 1241, 1144,
Reduction of syn-3 with H2 in the presence of Pd-C —
typical procedure
To a solution of syn-3b (30 mg, 0.097 mmol) in ethyl ace-
tate (40 mL) was added Pd-C (5%, 15 mg) and stirred for
24 h under the hydrogen atomosphere at room temp. The re-
action mixture was concentrated. The residue was chroma-
tographed over silica gel (Wako C-300, 100 g) with hexane–
benzene (1:1) as eluents to give anti-8b (18.1 mg, 60%) as a
colorless solid. Recrystallization from methanol gave anti-
10-exo,11-endo-dimethyl-7,13-dimethoxy[3.2]metacyclophane
(anti-8b) as colorless prisms, mp 84–85°C. 1H NMR
(CDCl3) δ: 0.95 (3 H, d, J = 7.3), 1.68 (3 H, d, J = 7.3),
1.80–2.00 (2 H, m), 2.00–2.15 (1 H, m), 2.17–2.34 (1 H, m),
2.33–2.46 (1 H, m), 2.68–2.80 (2 H, m), 3.61–3.76 (1 H, m),
3.78 (3 H, s), 3.85 (3 H, s), 4.87 (1 H, d, J = 2.4), 5.24 (1 H,
d, J = 2.4), 6.78 (2 H, d, J = 8.3), 6.93–7.01 (2 H, m). MS
m/z: M+ 310. Anal. calcd. for C21H26O2 (310.44): C 81.25, H
8.44; found: C 81.12, H 8.28.
1
1029, 810 cm–1. H NMR (CDCl3) δ: 2.44–2.55 (2 H, m),
2.76–2.81 (4 H, m), 4.02 (6 H, s), 6.92 (2 H, d, J = 7.8),
7.32 (2 H, d, J = 7.8), 8.11 (2 H, s). MS m/z: M+ 278. Anal.
calcd. for C19H18O2 (278.35): C 81.99, H 6.52; found: C
81.73, H 6.33.
Compound 10 was similarly prepared in 23% yield.
3,6-Dimethoxy-9,10-dimethyl-4,5-propanophenanthrene (10)
Compound anti-8c was similarly prepared in 95% yield.
Colorless prisms (methanol), mp 51–53°C. IR (KBr) υmax
:
2925, 1577, 1159, 1029, 803, 667 cm–1. 1H NMR (CDCl3) δ:
2.34–2.47 (2 H, m), 2.6–2.7 (4 H, m), 2.77 (6 H, s), 3.93 (6
H, s), 6.94 (2 H, d, J = 7.82), 7.18 (2 H, d, J = 7.82). MS
m/z: M+ 306. Anal. calcd. for C21H22O2 (306.41): C 82.32, H
7.24; found: C 82.21, H 7.18.
anti-11-exo,12-endo-Dimethyl-8,14-dimethoxy[4.2]meta-
cyclophane (anti-8c)
Colorless prisms (methanol), mp 93–94°C. 1H NMR
(CDCl3) (27°C), δ: 0.70–2.89 (16 H, broad m), 3.81 (6 H, s),
5.52–6.00 (2 H, s), 6.75 (2 H, d, J = 8.3), 6.86 (2 H, dd, J =
1
8.3, 2.4). H NMR (CDCl3–CS2 (1:3)) (–30°C) δ: 0.82–1.08
(2 H, broad s), 0.98 (3 H, d, J = 7.3), 1.45–1.62 (2 H,
broad s), 1.68 (3 H, d, J = 7.3), 2.09–2.28 (2 H, m), 2.55 (1
H, d, J = 7.3), 2.60–2.78 (2 H, m), 3.66 (1 H, d, J = 7.3),
3.80 (3 H, s), 3.87 (3 H, s), 5.61 (1 H, d, J = 2.4), 5.92 (1 H,
d, J = 2.4), 6.77 (2 H, d, J = 8.3), 6.86–6.96 (2 H, m). MS
m/z: M+ 306. Anal. calcd. for C22H28O2 (324.47): C 81.44, H
8.7; found: C 81.45, H 8.63.
Crystal data and refinement details for syn-3b and syn-3c
The unit cell constants were derived from least-squares
analysis of the settings, on an Enraf–Nonius CAD4 FR 586
diffractometer, for 16 reflections for syn-3b and 25 reflec-
tions for syn-3c in the range 23.9° < θ < 24.6° for syn-3b
and 22.0° < θ < 32.0° for syn-3c. The intensities of all inde-
pendent reflections with 4° < 2θ < 140° for syn-3b and
4° < 2θ < 144° for syn-3c were measured with ω-2θ scan
(ω scan width = 0.8 + 0.14 tan θ), Ni-filtered Cu–Kα radia-
tion (λ = 1.54184 Å) was used. The structure was solved un-
eventfully by direct method (SIR88)3 and difference Fourier
syntheses, and refined in full-matrix least-squares method.
Photoinduced cyclization of anti-6 in the presence of
iodine
The mixture of anti-6 (112 mg, 0.4 mmol) and iodine
(112.0 mg, 0.44 mmol) was dissolved in cyclohexane
© 2000 NRC Canada

1098
Can. J. Chem. Vol. 78, 2000
Table 4. Fractional atomic coordinates for the nonhydrogen at-
oms, with estimated standard deviations in parentheses, for syn-
10,11-dimethyl-7,13-dimethoxy[3.2]metacyclophan-10-ene (syn-
3b) and the isotropic equivalent displacement parameter defined
as Beq = 4/3[a2B11 + b2B22 + c2B33 + ab(cos γ)B12 + ac(cos β)B13
+ bc(cos α)B23].
Table 5. Fractional atomic coordinates for the nonhydrogen at-
oms, with estimated standard deviations in parentheses, for syn-
11,12-dimethyl-8,14-dimethoxy[4.2]metacyclophan-11-ene (syn-
3c) and the isotropic equivalent displacement parameter defined
as Beq = 4/3[a2B11 + b2B22 + c2B33 + ab(cos γ)B12 + ac(cos
β)B13 + bc(cos α)B23].
Atom
x
y
z
Beq
Atom
x
y
z
Beq
O1
O2
C1
C2
C3
C4
C5
C6
0.58744(8)
0.58885(9)
0.5922(1)
0.5935(1)
0.6570(1)
0.6552(1)
0.7184(1)
0.7827(1)
0.7865(1)
0.7221(1)
0.8556(1)
0.8882(1)
0.8532(1)
0.7824(1)
0.7784(1)
0.7144(1)
0.6526(1)
0.6539(1)
0.7188(1)
0.5314(1)
0.5353(1)
0.5874(2)
0.5836(2)
–0.3100(2)
0.1258(3)
–0.0376(3)
0.1181(3)
0.1609(3)
0.1503(3)
0.1598(4)
0.1715(4)
0.1857(3)
0.1915(3)
0.1796(4)
–0.0039(4)
–0.1260(4)
–0.2014(3)
–0.3265(3)
–0.3711(3)
–0.2848(3)
–0.1597(3)
–0.1296(3)
–0.1036(4)
0.2551(4)
–0.3650(5)
0.1146(5)
0.1709(1)
0.0417(1)
0.3212(2)
0.2716(2)
0.2246(2)
0.1103(2)
0.0735(2)
0.1508(2)
0.2636(2)
0.2973(2)
0.3506(2)
0.3781(2)
0.4492(2)
0.3877(2)
0.3038(2)
0.2340(2)
0.2433(2)
0.3269(2)
0.4022(2)
0.3690(2)
0.2568(2)
0.0623(3)
5.70(4)
5.76(4)
4.24(4)
4.02(4)
3.79(4)
4.45(4)
5.60(5)
5.68(5)
4.57(5)
4.04(4)
5.61(6)
5.90(6)
6.24(6)
4.86(5)
5.77(6)
5.53(6)
4.62(5)
4.17(4)
4.64(5)
6.07(6)
5.62(6)
7.40(8)
7.27(8)
O1
O2
C1
C2
C3
C4
C5
C6
0.4222(1)
0.4134(2)
0.4001(2)
0.3997(2)
0.3421(2)
0.3497(2)
0.2953(2)
0.2324(2)
0.2231(2)
0.2799(2)
0.1534(2)
0.1347(2)
0.1267(2)
0.1514(2)
0.2236(2)
0.2387(2)
0.3039(2)
0.3563(2)
0.3441(2)
0.2786(2)
0.4561(2)
0.4550(2)
0.4353(2)
0.4220(3)
0.3732(4)
0.8045(4)
0.4031(5)
0.5510(6)
0.6681(5)
0.7917(5)
0.8913(5)
0.8633(5)
0.7419(5)
0.6516(5)
0.6992(7)
0.5164(7)
0.4716(7)
0.2948(6)
0.2972(5)
0.2821(6)
0.3013(7)
0.3432(5)
0.3575(5)
0.3266(5)
0.2791(6)
0.6146(7)
0.3887(7)
0.8954(8)
0.9651(2)
0.8287(3)
0.7251(3)
0.6729(3)
0.6799(3)
0.7625(3)
0.7764(4)
0.7075(4)
0.6239(3)
0.6083(3)
0.5598(4)
0.5720(4)
0.6951(4)
0.7300(4)
0.7929(4)
0.9144(4)
0.9732(4)
0.9129(3)
0.7896(3)
0.7343(3)
0.7226(4)
0.6101(4)
1.0876(4)
0.9299(5)
6.25(7)
7.66(8)
4.76(8)
5.19(9)
4.64(8)
5.4(1)
6.2(1)
6.3(1)
5.12(9)
5.11(9)
6.8(1)
7.6(1)
7.4(1)
6.9(1)
5.6(1)
6.3(1)
6.3(1)
5.19(9)
4.55(8)
5.04(9)
6.3(1)
7.2(1)
7.6(1)
9.0(2)
C7
C8
C9
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
–0.0745(2)
5. (a) R.H. Mitchell and V. Boekelheide. J. Am. Chem. Soc. 96,
1547 (1974); (b) Y.-H. Lai and H.-L. Eu. J. Chem. Soc. Perkin
Trans. 1, 233 (1993).
6. H.A. Staab, W.R.K. Riebel, and C. Krieger. Chem. Ber. 118,
1230 (1985).
7. (a) J.E. McMurry, M.P. Fleming, K.L. Kees, and L.R. Krepski.
J. Org. Chem. 43, 3255 (1978); (b) J.E. McMurry. Acc. Chem.
Res. 16, 405 (1983); (c) J.E. McMurry, G.J. Haley, J.R. Matz,
J.C. Clardy, and G.V. Duyne. J. Am. Chem. Soc. 106, 5018
(1984); (d) J.E. McMurry. Chem. Rev. 89, 1513 (1989).
8. R.H. Mitchell and S.A. Weerawana. Tetrahedron Lett. 27, 453
(1986).
All calculations were performed on a Micro VAX 3100
computer using a MolEN program package.4
Crystallographic data for syn-3b and syn-3c are given in
Table 3.
The refined non-hydrogen atomic coordinates for syn-3b
and syn-3c are listed in Tables 4 and 5, respectively, while
the hydrogen coordinates, temperature factors (anisotropic
for carbon atoms), scale factor, and secondary estimation co-
efficient for syn-3b and syn-3c are available on request.5
9. D. Tanner and O. Wennerström. Acta Chem. Scand. Ser. B, 37,
693 (1983).
References
1. T. Yamato, K. Fujita, K. Okuyama, and H. Tsuzuki. New J.
Chem. 24, 221 (2000).
2. M. Pelligrin. Recl. Trav. Chim. Pays-Bas Belg. 18, 458 (1899).
3. R.H. Mitchell, T.K. Vinod, and G.W. Bushnell. J. Am. Chem.
Soc. 107, 3340 (1985).
10. H. Hopf and C. Mlynek. J. Org. Chem. 55, 1361 (1990).
11. (a) H.-F. Grützmacher, E. Neumann, F. Ebmeyer, K. Albrecht,
and P. Schelenz. Chem. Ber. 122, 2291 (1989); (b) H.-F.
Grützmacher and E. Neumann. Chem. Ber. 126, 1495 (1993);
(c) H.-F. Grützmacher and G. Nolte. Chem. Ber. 127, 1157
(1994); (d) H.-F. Grützmacher, A. Mehdizadeh, and A.
Mülverstedt. Chem. Ber. 127, 1163 (1994).
4. Y. Fujise, Y. Nakasato, and S. Itô. Tetrahedron Lett. 27, 2907
(1986).
4 MolEN, an interactive structure solution procedure. Enraf–Nonius, Delft, The Netherlands. 1990.
5 Hydrogen coordinates, temperature factors (anisotropic for carbon atoms), scale factors, and secondary estimation coefficients have been de-
posited as supplementary material and may be purchased from The Depository of Unpublished Data, Document Delivery, CISTI, National
Research Council Canada, Ottawa, Ontario, Canada, K1A 0S2 ( for information on ordering electronically). Crystallographic data for the
structure(s) reported in this paper havebeen deposited with the Cambridge Crystallographic Data Centre (CCDC). Copies of the data can be
obtained, free of charge, on application to The Director, (CCDC), 12 Union Road, Cambridge CB2 1EZ, U.K. (Fax: 44-1223-336033 or e-
mail: deposit@ccdc.cam.ac.uk).
© 2000 NRC Canada

Yamato et al.
1099
12. M. Tashiro and T. Yamato. J. Org. Chem. 43, 1413 (1978).
13. (a) T. Yamato, J. Matsumoto, M. Kajihara, and M. Tashiro.
Chem. Express, 5, 769 (1990); (b) T. Yamato, J. Matsumoto,
S. Ide, K. Tokuhisa, K. Suehiro, and M. Tashiro. J. Org. Chem.
57, 5243 (1992); (c) T. Yamato, J. Matsumoto, K. Tokuhisa,
M. Kajihara, K. Suehiro, and M. Tashiro. Chem. Ber. 125,
2443 (1992).
14. M. Tashiro, A. Tsuge, T. Sawada, T. Makishima, S. Horie, T.
Arimura, S. Mataka, and T. Yamato. J. Org. Chem. 55, 2404
(1990).
15. (a) Cyclophanes. Vol. 1. P.M. Keehn and S.M. Rosenfield (Ed-
itors). Academic Press, New York, 1983. Chap. 6, p. 428;
(b) F. Vögtle. Cyclophane-Chemistry, Wiley, Chichester, 1993.
16. D. Krois and H. Lehner. Tetrahedron, 38, 3319 (1982).
17. (a) H. Förster and F. Vögtle. Angew. Chem. 89, 443 (1977);
Angew. Chem. Int. Ed. Engl. 16, 429 (1977); (b) R.H. Mitch-
ell, K.S. Weerawana, and G.W. Bushnell. Tetrahedron Lett. 25,
907 (1984). (c) K. Böckman and F. Vögtle. Chem. Ber. 114,
1065 (1981); (d) M.F. Semmelhack, J.J. Harrisson, D.C.
Young, Y. Guitierrez, S. Rafii, and J. Clardy. J. Am. Chem.
Soc. 107, 7508 (1985).
(1983); (e) J.A. Kanters, A. Schouten, E. Steinwender, J.H.
van der Maas, L.C. Groenen, and D.N. Reinhoudt. J. Mol.
Struct. 269, 49 (1992).
25. R.W. Griffin, Jr., R.W. Baugman, and C.E. Ramey. Tetrahedron
Lett. 5419 (1968).
26. (a) T. Yamato, J. Matsumoto, S. Ide, K. Suehiro, K.
Kobayashi, and M. Tashiro. Chem. Ber. 126, 447 (1993); (b) T.
Yamato, M. Sato, K. Noda, J. Matsumoto, and M. Tashiro. J.
Chem. Res. Synop. 394 (1993); J. Chem. Res. Miniprint, 2601
(1993); (c) T. Yamato, K. Fujita, T. Ando, S. Ide, Y. Nagano,
and M. Tashiro. J. Chem. Res. Synop. 264 (1996); J. Chem.
Res. Miniprint, 1434 (1996); (d) T. Yamato, K. Fujita, S. Ide,
and Y. Nagano. J. Chem. Res. Synop. 190 (1997); J. Chem.
Res. Miniprint, 1301 (1997).
27. (a) M. Tashiro and T. Yamato. J. Org. Chem. 46, 4556 (1981);
(b) M. Tashiro and T. Yamato. J. Org. Chem. 48, 1461 (1983).
28. R.E. Merrifield and W.D. Phillips. J. Am. Chem. Soc. 80, 2778
(1958).
29. (a) R. Boschi and W. Schmidt. Angew. Chem. Int. Ed. Engl.
12, 402 (1973); (b) T. Sato and T. Takemura. J. Chem. Soc.
Perkin Trans. 2, 1195 (1976); (c) S. Hayashi and T. Sato. Nip-
pon Kagaku Zasshi, 91, 950 (1970); (d) D.J. Cram and R.H.
Bauer. J. Am. Chem. Soc. 81, 5971 (1959); (e) L.A. Singer
and D.J. Cram. J. Am. Chem. Soc. 85, 1080 (1963); (f) M.
Sheehan and D.J. Cram. J. Am. Chem. Soc. 91, 3553 (1969);
(g) T. Sato and K. Nishiyama. J. Chem. Soc. Chem. Commun.
220 (1973); (h) T. Sato and K. Nishiyama. J. Org. Chem. 37,
3254 (1972); (i) M. Tashiro, T. Yamato, K. Kobayashi, and T.
Arimura. J. Org. Chem. 52, 3196 (1987); (j) T. Yamato, S. Ide,
K. Tokuhisa, and M. Tashiro. J. Org. Chem. 57, 271 (1992).
30. (a) T. Yamato, J. Matsumoto, N. Shinoda, S. Ide, M.
Shigekuni, and M. Tashiro. J. Chem. Res. Synop. 178 (1994);
(b) T. Yamato, H. Kamimura, F. Zhang, and H. Tsuzuki. Can.
J. Chem. 76, 997 (1998).
31. (a) F.B. Mallory, C.S. Wood, and J.T. Gordon. J. Am. Chem.
Soc. 86, 3094 (1964); (b) R. Srinivasan and J.N.C. Hsu. J. Am.
Chem. Soc. 93, 2816 (1971); (c) M.V. Sargent and C.J.
Timmons. J. Am. Chem. Soc. 85, 2186 (1963); (d) P.H.G. Op
Het Veld and W.H. Laarhoven. J. Am. Chem. Soc. 99, 7221
(1977); (e) R. Srinivasan, V.Y. Merrit, J.N.C. Hsu, P.H.G. Op
Het Veld, and W.H. Laarhoven. J. Org. Chem. 43, 980 (1978);
(f) C.S. Wood and F.B. Mallory. J. Org. Chem. 29, 3373 (1964);
(g) K.A. Muszkat and E. Fischer. J. Chem. Soc. B, 662 (1967).
32. (a) H. Blaschke, C.E. Ramey, I. Calder, and V. Boekelheide. J.
Am. Chem. Soc. 92, 3675 (1970); (b) C.E. Ramey and V.
Boekelheide. J. Am. Chem. Soc. 92, 3681 (1970).
18. R.W. Hoffmann. Angew. Chem. 104, 1147 (1992); Angew.
Chem. Int. Ed. Engl. 31, 1124 (1992).
19. (a) S. Cerrini, E. Giglio, F. Mazza, and N.V. Pavel. Acta
Crystallogr. Sect. B: Struct. Crystallogr. Cryst. Chem. B35,
2605 (1979); (b) J.A. Hyatt, E.N. Duesler, D.Y. Curtin, and
I.C. Paul. J. Org. Chem. 45, 5074 (1980); (c) A. Collet and J.
Gabard. J. Org. Chem. 45, 5400 (1980); (d) A. Collet. Tetrahe-
dron, 43, 5725 (1987).
20. (a) R.C. Cookson, B. Halton, and I.D.R. Stevens. J. Chem.
Soc. B, 767 (1968); (b) J.E. Baldwin and D.P. Kelly. J. Chem.
Soc. Chem. Commun. 1664 (1968).
21. (a) J.F. Manville and G.E. Troughton. J. Org. Chem. 38, 4278
(1973); (b) J. Canceil, J. Gabard, and A. Collet. J. Chem. Soc.
Chem. Commun. 122 (1983); (c) G. Combaut, J.-M.
Chantraine, J. Teste, J. Soulier, and K.-W. Glombitza. Tetrahe-
dron Lett. 1699 (1978); (d) J. Bosch, J. Canals, and R.
Granados. Anal. Quim. 72, 709 (1976); (e) T. Yamato, N.
Sakaue, L.K. Doamekpor, and M. Tashiro. J. Chem. Res.
Synop. 176 (1994).
22. (a) T. Yamato, H. Sakamoto, K. Kobayashi, and M. Tashiro. J.
Chem. Res. Synop. 352 (1986); J. Chem. Res. Miniprint, 2866
(1986); (b) T. Yamato, J. Matsumoto, M. Kajihara, K.
Tokuhisa, K. Suehiro, and M. Tashiro. J. Org. Chem. 57, 5154
(1992); (c) T. Yamato, J. Matsumoto, K. Tokuhisa, K. Suehiro,
and M. Tashiro. J. Chem. Soc. Chem. Commun. 865 (1992);
(d) T. Yamato, J. Matsumoto, M. Sato, K. Noda, and M.
Tashiro. J. Chem. Soc. Perkin Trans 1, 1299 (1995).
23. (a) M. Tashiro and T. Yamato. J. Am. Chem. Soc. 104, 3701
(1982); (b) M. Tashiro, K. Kobayashi, and T. Yamato. Chem.
Lett. 327 (1985).
33. (a) R.H. Mitchell, T.K. Vinod, G.J. Bodwell, K.S.
Weerawarna, W. Anker, R.V. Williams, and G.W. Bushnell.
Pure Appl. Chem. 58, 15 (1986); (b) Y.-H. Lai and S.-M. Lee.
J. Org. Chem. 53, 4472 (1988); (c) Y.-H. Lai and H.-L. Eu. J.
Chem. Soc. Perkin Trans. 1, 233 (1993).
24. (a) T. Yamato, J. Matsumoto, M. Sato, K. Noda, T. Moriguchi,
and M. Tashiro. Liebigs Ann. 995 (1995); (b) C.D. Gutsche.
Calixarenes. Royal Society of Chemistry, Cambridge, 1989;
(c) J. Vicens and V. Böhmer. Calixarenes: A Versatile Class of
Macrocyclic Compounds. Kluwer Academic Publishers, Cam-
bridge, 1990; (d) C.D. Gutsche. Acc. Chem. Res. 16, 161
34. (a) M. Tashiro and T. Yamato. J. Org. Chem. 46, 1543 (1981);
(b) M. Tashiro, K. Koya, and T. Yamato. J. Am. Chem. Soc.
104, 3707 (1982); (c) M. Tashiro and T. Yamato. J. Org.
Chem. 50, 2939 (1985); (d) T. Yamato, T. Arimura, and M.
Tashiro. J. Chem. Soc. Perkin Trans. 1, 1 (1987).
© 2000 NRC Canada