Synthesis and demethylation of 4,22-dimethoxy[2.10]metacyclophan-1-yne with BBr3 to afford a novel [10](2,9)-5a,11a-benzofuro-5a-bora-11- bromochromenophane

Article abstract of DOI:10.1139/v2012-014

4,22-Dimethoxy[2.10]metacyclophan-1-yne was prepared by bromination of [2.10]metacyclophan-1-ene followed by the dehydrobromination of the bromine adduct with KOBu-t. Treatment of 4,22-dimethoxy[2.10]metacyclophan-1-yne with BBr₃ in CH₂Cl₂ at room temperature led to the demethylation and a successive intramolecular cyclization reaction to afford a novel [10](2,9)-5a,11a-benzofuro-5a-bora-11-bromochromenophane in good yield. Similar treatment of a mixture of the corresponding meso-and dl-1,2-dibromo-4,22-dimethoxy[2.10]metacyclophane with BBr₃ in CH₂Cl₂ under the same conditions described above afforded cis-4b,9b-dihydro[10]benzofuro[3,2-b]benzofuranophane in 83% yield.

Full text of DOI:10.1139/v2012-014

441
Synthesis and demethylation of 4,22-dimethoxy
[2.10]metacyclophan-1-yne with BBr3 to afford a
novel [10](2,9)-5a,11a-benzofuro-5a-bora-11-
bromochromenophane
Yuki Uchikawa, Kazuya Tazoe, Syogo Tanaka, Xing Feng, Taisuke Matsumoto,
Junji Tanaka, and Takehiko Yamato
Abstract: 4,22-Dimethoxy[2.10]metacyclophan-1-yne was prepared by bromination of [2.10]metacyclophan-1-ene followed
by the dehydrobromination of the bromine adduct with KOBu-t. Treatment of 4,22-dimethoxy[2.10]metacyclophan-1-yne
with BBr3 in CH2Cl2 at room temperature led to the demethylation and a successive intramolecular cyclization reaction to
afford a novel [10](2,9)-5a,11a-benzofuro-5a-bora-11-bromochromenophane in good yield. Similar treatment of a mixture of
the corresponding meso- and dl-1,2-dibromo-4,22-dimethoxy[2.10]metacyclophane with BBr3 in CH2Cl2 under the same
conditions described above afforded cis-4b,9b-dihydro[10]benzofuro[3,2-b]benzofuranophane in 83% yield.
Key words: metacyclophan-1-ene, dehydrobromination, metacyclophan-1-yne, double intramolecular cyclization, benzofu-
ranophane.
Résumé : On a préparé le 4,22-diméthoxy[2,10]métacyclophan-1-yne par une bromuration du 4,22-diméthoxy[2,10]métacy-
clophan-1-ène suivie d’une déshydrobromuration de l’adduit bromé à l’aide de tert-butylate de potassium. La réaction du
4,22-diméthoxy[2,10]métacyclophan-1-yne avec du BBr3, en solution dans le CH2Cl2, à la température ambiante, conduit
successivement à une déméthylation et une réaction de cyclisation intramoléculaire qui fournit un nouveau [10](2,9)-5a,11a-
benzofuro-5a-bora-11-bromochroménophane, avec un bon rendement. Un traitement semblable d’un mélange de méso- et de
dl- 1,2-dibromo-4,22-diméthoxy[2,10]métacyclophane avec du BBr3, en solution dans le CH2Cl2, dans les conditions décri-
tes plus haut, conduit au 4b,9b-dihydro[10]benzofuro[3,2-b]benzofuranophane, avec un rendement de 83 %.
Mots‐clés : métacyclophan-1-ène, déshydrobromuration, métacyclophan-1-yne, double cyclisation intramoléculaire, benzofu-
ranophane.
[Traduit par la Rédaction]
Introduction
MCP-n-enes, which were considerably strained with bent tri-
ple bonds. Although we attempted to prepare [2.3]- and
[2.4]-MCP-1-ynes by the dehydrobromination of the corre-
sponding 1,2-dibromo[2.3]- and [2.4]-MCPs,13 no formations
of the desired [2.3]- and [2.4]-MCP-ynes were observed be-
cause of the considerably strained bent triple bonds. Instead,
only 1-bromo[2.3]- and [2.4]-MCP-1-enes, along with [2.3]-
and [2.4]-MCP-1-ones, were obtained. On the other hand,
we succeeded in preparing the larger ring sized 8,22-di-
methoxy[2.8]- and 8,24-dimethoxy[2.10]-MCP-1-ynes with
bent triple bonds by the bromination–dehydrobromination of
the corresponding [2.n]MCP-1-enes.13
Cyclophanes belong to one of the remarkable compound
classes that has attracted extensive studies.1–3 In 1982, Psiorz
and Hopf reported the identification of some elusive strained
paracyclophyne intermediates, which were indirectly con-
firmed by the fact that giving Diels–Alder adducts were pro-
duced with dienophiles or that trimerization to the
hexaphenyl benzene derivatives occurred.4–8 Later, Meijere
and Wong5 reported the existence of the strained cyclophynes
as an intermediate, which was established by a trapping
method. Ramming and Gleiter9 reported the syntheses of
[n]MCP-diynes (MCP = metacyclophane) and their transfor-
mation of propargylic moieties into allenic moieties, as well
as reactions with strong bases. Recently, Kawase and co-
workers10–12 reported the synthesis of [2n]MCP-n-ynes by
bromination–dehydrobromination of the corresponding
On the other hand, recently, Yamaguchi and co-workers14–18
reported the double intramolecular cyclizations of diaryl-
acetylenes to construct a series of fully ring-fused ladder p-
conjugated skeletones with various main group elements, such
Received 4 November 2011. Accepted 16 January 2012. Published at www.nrcresearchpress.com/cjc on 4 April 2012.
Y. Uchikawa, K. Tazoe, S. Tanaka, X. Feng, and T. Yamato. Department of Applied Chemistry, Faculty of Science and Engineering,
Saga University, Honjo-machi 1, Saga 840-8502, Japan.
T. Matsumoto and J. Tanaka. Institute for Material Chemistry and Engineering, Kyushu University, 6-1, Kasugakoen, Kasuga 816-8580,
Japan.
Corresponding author: Takehiko Yamato (e-mail: yamatot@cc.saga-u.ac.jp).
Can. J. Chem. 90: 441–449 (2012)
doi:10.1139/V2012-014
Published by NRC Research Press

442
Can. J. Chem. Vol. 90, 2012
as Si, B, P, and S, as the bridging moieties. Thus, there
is substantial interest in the synthesis of the larger sized
[2.n]MCP-1-ynes having nucleophilic substituents such as OH
and OMe groups at the ortho position to the acetylenic linkage,
which can afford convenient starting materials for the attempted
preparation of a series of fully ring-fused [2.n]cyclophanes by
the double intramolecular cyclizations of the diarylacetylene
moiety (Scheme 1). In this paper, we describe the first
preparation of 4,22-dimethoxy[2.10]MCP-1-ene using the
low-valent titanium-induced McMurry reaction and their con-
version to 4,22-dimethoxy[2.10]MCP-1-yne, which was treated
with BBr3 to afford a novel [10](2,9)-5a,11a-benzofuro-5a-
bora-11-bromochromenophane by the intramolecular cycliza-
tions of the diarylacetylene moiety.
Scheme 1. Double intramolecular cyclization of diarylacetylenes and
hydroxy[2.n]metacyclophan-1-ynes
X
Double intramolecular
cyclization
Ar
X
Ar
Ar
X
Ar
E= SiR2, S, BAr, PR2
X
(CH2)n
(CH2)n
O
OH
Double intramolecular
cyclization
O
HO
Results and discussion
ray crystallographic analyses of (E)-4 clearly show that the
compound also adopts the anti conformation in the solid
state. In addition, the double bond adopts the E configura-
tion. These results seem to indicate that the double bond in
(E)-4 plays an important role in the fixation of the conforma-
tion in the solid state.
In (E)-4 the bond distance of C1–C2 is 1.341 Å, which is
almost the same value as the distance between carbon atoms
in ethylene. The bond distances of C2–C3 and C1–C23 are
1.472 and 1.474Å, respectively, which are slightly shorter
than those of C7–C9 (1.545 Å) and C18–C19 (1.524 Å). The
dihedral angles of C9–C10–C11–C12–C13–C14–C15–C16–C17–
C18–C1–C2 between C3–C4–C5–C6–C7–C8 and C19–C20–C21–
C22–C23–C24 are different values, 3.15° and 0.15°, respec-
tively, showing that the aromatic rings adopt the asymmetri-
cal conformation in the molecule. This reflects the bond
angles in the ethylenic bridge chain; the bond angles of C1–
C2–C3 and C23–C1–C2 are different values (131.74° and
122.49°) that are larger than those of ethylene.
1,10-Bis(4-methoxyphenyl)decane (2) was prepared ac-
cording to our previous reports.19–24 The cross-coupling
reaction of 4-methoxyphenylmagnesium bromide with 1,10-
dibromodecane was carried out in the presence of cuprous
bromide as a catalyst in a mixture of hexamethylphosphoric
triamide (HMPA) and tetrahydrofuran (THF) at reflux tem-
perature to give the desired 1,10-bis(4-methoxyphenyl)decane
(2) in 82% yield. The TiCl4-catalysed formylation of com-
pound 2 with Cl2CHOMe at 20 °C led to regioselective for-
mylation at the meta positions of the 1,10-diphenylalkane,
affording the desired 1,10-bis(3-formyl-4-methoxyphenyl)
decane (3) in 83% yield. Compound 3 was subjected to re-
ductive coupling by the McMurry reaction.25–43 The novel
desired [2.10]MCP-1-ene (4) was obtained in 94% yield
along with the corresponding 1,2-diol (5). The 1H NMR
spectrum of 4 shows two kinds of methoxy protons, each as
a singlet. By careful column chromatography (silica gel,
Wako C-300), two isomers, (E)-4 and (Z)-4 (Scheme 2),
were separated in 52% and 42% yield, respectively.
The structure of diol 5 was also determined on the basis of
its elemental analyses and spectral data. Thus, we reported44
the structure of anti-1,2-dihydroxy-6,13-dimethoxy[2.3]MCP
and assigned it as a trans-diol with a exo–exo arrangement.
We assigned the structure of 5 in a similar fashion. How-
ever, in the case of 5, the similar upfield shift of the internal
aromatic proton (d 4.95 ppm for anti-1,2-dihydroxy-6,13-
dimethoxy[2.3]MCP)1–3,45,46 was not observed, but appeared
in the normal aromatic region at d 6.72 ppm (J = 2.4 Hz).
This observation strongly suggests 5 adopts a syn confor-
mation, different from that in anti-1,2-dihydroxy-6,13-
dimethoxy[2.3]MCP. The other two aromatic protons was
observed at d 6.72 (H5,21, J = 8.4 Hz) and 6.95 (H6,20, J =
2.4, 8.4 Hz) ppm, respectively. Furthermore, the bridged
methine protons show a downfield shift at d 4.81 ppm as a
doublet (J = 2.1 Hz), whereas those of 1,2-dihydroxy-6,13-
dimethoxy[2.3]MCP are at d 4.34 ppm. Thus, the bridged
methine protons of 5 are in a strongly deshielding region
of the oxygen atom of the methoxy groups on the benzene
ring. These observations are strongly supported because the
two OH groups are in an exo, exo arrangement and, there-
fore, 5 was found to be a cis-diol.
The structures of products (E)-4 and (Z)-4 were deter-
mined on the basis of their elemental analyses and spectral
1
data. H NMR signals of the olefinic protons for E- and Z-
olefins should be observed at d > 7.4 ppm (E) and d <
1
6.9 ppm (Z).44 The H NMR spectrum of (E)-4 in CDCl3
shows a singlet at d 7.36 ppm for olefinic protons and a dou-
blet (J = 2.4 Hz) at d 7.30 ppm for one aromatic proton
(H8,24), which is in a strongly deshielding region of the
1
bridged double bond. In contrast, the H NMR spectrum of
(Z)-4 in CDCl3 shows a singlet at d 6.70 ppm for olefinic
protons and a set of doublets (J = 2.4 Hz) at d 6.76, 6.98,
and 7.03 ppm for the aromatic protons, which were observed
at higher field owing to the strong shielding effect of the op-
posing benzene ring. These data strongly support that the
structure of (E)-4 is the E configuration and the structure of
(Z)-4 is the Z configuration, both having syn conformation.
The structure of the syn-confomer is also readily assigned
from the chemical shift of the internal proton Hi at d
7.30 ppm for (E)-4 and d 7.03 ppm for (Z)-4.
Single-crystal X-ray diffraction structures of (E)-4 recrys-
tallized from hexane are illustrated in Fig. 1 with the atom-
numbering system.
Compound (E)-4 crystallized in the monoclinic space
group P121/a. Compound (E)-4 was located at general posi-
tions in the asymmetric unit of the crystal structure. The X-
Attempted bromination of (Z)-4,22-dimethoxy[2.10]MCP-
1-ene (Z)-4 with an equimolar amount of benzyltrimethylam-
monium tribromide (BTMA Br3), which was found to be a
convenient solid brominating agent,47 carried out in a
Published by NRC Research Press

Uchikawa et al.
443
Scheme 2. Synthesis of (Z)- and (E)-4,22-dimethoxy[2.10]MCP-1-ene, (Z)-4 and (E)-4.
OMe
1. Mg, THF
Cl2CHOMe
(CH2)10
MeO
OMe
Br,
2. Br(CH2)10
CuBr, HMPA
(82%)
TiCl4 in CH2Cl2
rt for 3 h
Br
2
(83%)
1
OHC
MeO
CHO
OMe
TiCl4-Zn
(CH2)10
in THF
reflux for 60 h
3
CH2)10
(CH2)10
(CH2)10
HO
OH
1
2
19
+
+
7
22
OMe
H
H
4
MeO
OMe
MeO
MeO
OMe
(Z)-4
(E)-4
5
(42%)
(52%)
(4%)
Fig. 1. Single-crystal X-ray diffraction structures of (E)-4. Hydrogen
Scheme 3. Bromination of (Z)-4 with BTMA Br3.
atoms are omitted for clarity.
(CH2)10
(CH2)10
H
H
H
BTMA Br3
CH2Cl2
room temp.
for 5min
(Z)-4
+
Br
H
OMe
Br
OMe
meso-6
(42%)
Br
MeO
Br
MeO
dl-6
(52%)
(80%)
as that for 7 (Scheme 4). Interestingly, the signals of the
acetylenic carbons were observed at slightly lower field (d
91.48 ppm for 7) than that of 11 (d 89.69 ppm, Scheme 5);
this reflects the relatively small strain in the triple bond
owing to bending and is almost the same value of that of
[24]MCP-1,9,17,25-tetrayne (d 92.20 ppm), but much lower
than that of 1,5-cyclooctadiyne (d 95.8 ppm)48 or [23]MCP-
1,9,17-triyne (d 99.86 ppm).11
dichloromethane solution at room temperature for 5 min led
to the expected cis- and trans-adducts 6 (endo–endo–Br and
endo–exo–Br) to the bridged double bond in a ratio of 45:55
in 80% yield. Similar treatment of (E)-4 with BTMA Br3
under the same reaction conditions afforded a mixture of
meso-6 and rac-6 (Scheme 3) in 91% yield in a ratio of
45:55.
Single-crystal X-ray diffraction structures of 7 recrystal-
lized from hexane are illustrated in Fig. 2 with the atom-
numbering system. Compound 7 crystallized in the mono-
clinic space group P21/a (Z = 8). All remaining hydrogen
atoms are not shown for clarity. The structure was solved by
direct-methods (Sir2002) and refined using the full-matrix
least-squares method and Fourier synthesis. The X-ray struc-
ture determination of 7 clearly indicates that the structure of
7 is also the syn-conformer in the solid state, and the two
methoxy groups are lying on the same side of the inner ring
toward the outer direction to avoid steric repulsion with the
bridge chain, the same as in (E)-4. The bond distance of C1–
C2 is 1.20 Å, which is almost equal to the distance between
carbon atoms in acetylene. The bond distances of C2–C3 and
C1–C23 are 1.43 and 1.43 Å, respectively, which are much
shorter than those of C7–C9 (1.52 Å) and C18–C19 (1.51 Å).
Interestingly, the acetylenic moiety in the bridge chain does
not adopt a different linear structurethan reference compound
11; the bond angles of C1–C2–C3 and C2–C1–C23 are unusual
values, 169.6°and 170.2°. Thus, this clearly shows that 7 is a
slightly bent molecule and supports the lower field shifts of
When treated with potassium tert-butoxide in refluxing
HOBu-t at 80 °C for 2 h, bromine adduct 6 gave the didehy-
drobromination product [2.10]MCP-1-yne (7) in 72% yield.
The structure of 7 was determined on the basis of its ele-
1
mental analysis and spectral data. The H NMR spectrum of
7 shows two internal protons as a doublet at d 7.39 (H8,24
,
,
J = 2.1 Hz) ppm and two aromatic protons at d 6.78 (H5,21
J = 8.4 Hz) and 7.03 (H6,20, J = 2.1, 8.4 Hz) ppm. The
chemical shift for the internal protons at normal aromatic
protons strongly supports that the structure of 7 is the syn-
conformer. A deshielded internal proton was observed in the
NMR spectrum of 7 at d 7.39 ppm in comparison with other
aromatic protons, which is in a strongly deshielding region
owing to the p-electrons of the triple bond. The chemical
shifts of the 1H and 13C NMR signals arising from the
benzene rings of 7 are comparable to those of the acyclic
reference compound 11,13 which was prepared from 2-
formyl-5-methylanisole (8) in three. steps, the same procedure
Published by NRC Research Press

444
Can. J. Chem. Vol. 90, 2012
Scheme 4. Didehydrobromination of 6 with potassium tert-butoxide.
Scheme 6. Treatment of 7 with BBr3 in CH2Cl2.
(CH2)10
(CH2)10
KOBut
6
19
1
2
7
HOBut
80°C for 2 h
(72%)
22
4
MeO
OMe
HO
OH
BBr3 in CH2Cl2
7
12
7
(CH2)10
room temp.
for 0.5 h
(83%)
Br
Scheme 5. Synthesis of acyclic reference compound 11.
11
9
Me
2
OMe
CHO
Me
BTMA-Br3
TiCl4-Zn
B
O 5
6
O
in THF
reflux for 24 h
(70%)
C
H2Cl2
room temp.
for 5 min
OMe
13
Me
MeO
(E)-9
Me
8
(84%)
was assigned the structure, [10](2,9)-5a,11a-benzofuro-5a-
bora-11-bromochromenophane.
Me
Br
Me
t
Me
KOBu
Although the detailed mechanism of formation of
[10]benzofurochromenophane (13) is not clear at the
present stage, one might assume the reaction pathway as
shown in Scheme 7. The present BBr3-induced transforma-
tion from 7 to 13 probably occurred by demethylation of
one methoxy group to afford the corresponding intermediate
A followed by the second demethylation reaction along with
the intramolecular cyclization reaction to afford the inter-
mediate B, from which the electrophilic attack to the triple
bond to generate the vinyl cation intermediate C occurred.
Succesively, the nucleophilic attack to the vinyl cation inter-
mediate C afforded compound 13 (Scheme 7). The present
cyclization of the intermediate B to C might be attributable
to conformational flexibility of the intermediate B and a
short distance among the ethynyl group and boron atom as
an electrophile owing to the syn-MCP skeletone. In fact,
similar treatment of reference compound 11 with BBr3
under the same conditions afforded only the intractable mix-
ture of products. No formation of the corresponding benzo-
furochromene was observed under the conditions used.
To study the present [10]benzofurochromenophane forma-
tion reaction in more detail, we attempted to carry out the
treatment of dibromide 6 with BBr3. In fact, the treatment of
a mixture of meso- and dl-6 with BBr3 in CH2Cl2 under the
same conditions described above afforded cis-4b,9b-dihydro
[10]benzofuro[3,2-b]benzofuranophane (15) in 83% yield,
but not [10]benzofurochromenophane (Scheme 8).
The present BBr3-induced transformation from 6 to 15
probably occurred by the demethylation of methoxy groups
to afford the corresponding phenol derivative D, followed by
a nucleophilic attack by phenolic oxygen to the bromide car-
bon at the C2 carbon to afford the benzofuran intermediate E,
from which the second nucleophilic attack to the bromide
carbon at the C3 position of benzofuran occurred to afford
benzofuro[3,2-b]benzofuranophane skeletone intermediate G.
The second cyclization of the intermediate E to F might be
attributable to conformational flexibility of the intermediate E
around the diaryl linkage of 2-arylbenzofuran. Deprotonation
from the intermediate G afforded compound 15 (Scheme 9).
From this proposed reaction mechanism for the BBr3-induced
transformation of 6 to 15, one might assume the importance
t
KOBu
OMe
Br
80°C for 24 h
(53%)
MeO
OMe
MeO
10
11
Fig. 2. Single-crystal X-ray diffraction structures of 7. Hydrogen
atoms are omitted for clarity.
the signals of the acetylenic carbons in its 13C NMR spec-
trum.
Attempted demethylation of 7 to afford 12 with trime-
thylsilyl iodide in acetonitrile solution42–52 under various
conditions failed. Only an intractable mixture of products
was obtained. Interestingly, treatment of 7 with BBr3 in
CH2Cl2 at room temperature for 0.5 h afforded a novel
[10](2,9)-5a,11a-benzofuro-5a-bora-11-bromochromenophane
(13) in 83% yield (Scheme 6). No formations of the ex-
pected 4,22-dihydroxy[2.10]MCP-1-ene (12) or [10]benzo-
furo[3,2-b]benzofuranophane (Scheme 1) derived from the
double intramolecular cyclizations of diarylacetylene and the
OH groups of 12 were observed under the conditions used.
The structure of 13 was elucidated based on its elemental
analysis and spectral data. Especially, the mass spectral data
for 13 (M+ = 435, 437) strongly supports one bromine atom
1
containing product. The H NMR spectrum in CDCl3 exhib-
ited six aromatic protons at d 6.84 (d, J = 8.4), 6.86 (d, J =
2.4 Hz), 7.01 (dd, J = 2.4, 8.4 Hz), 7.18 (d, J = 8.4 Hz),
7.23 (dd, J = 1.2, 8.4 Hz), and 7.95 (d, J = 1.2 Hz) ppm,
which were clearly associated with the unsymmetrical struc-
ture of 13. On the basis of the spectral data, compound 13
Published by NRC Research Press

Uchikawa et al.
445
Scheme 7. Proposed reaction mechanism for the formation of 13.
(CH2)10
(CH2)10
BBr3
7
-MeBr
-MeBr
O
O
O
OMe
B
BBr2
Br
A
B
(CH2)10
Br-
13
-Br-
B
O
O
C
Scheme 8. Reaction of a mixture of meso- and dl-6 with BBr3 in
CH2Cl2.
netic resonance (1H NMR) spectra were recorded on a Nip-
pon Denshi JEOL FT-300 spectrometer. Chemical shifts are
reported as d values (ppm) relative to internal Me4Si. Mass
spectra were obtained on a Nippon Denshi JIR-AQ2OM
mass spectrometer at an ionization energy of 70 eV using a
direct-inlet system through GLC; m/z values reported include
the parent ion peak. Infrared (IR) spectra were obtained on a
Nippon Denshi JIR-AQ2OM spectrophotometer as KBr
disks. Elemental analyses were performed with a Yanaco
MT-5. Gas–liquid chromatograph (GLC) analyses were per-
formed with a Shimadzu GC, GC-14A (silicone OV-1, 2 m;
programmed temperature rise, 12 °C min–1; carrier gas, nitro-
gen, 25 mL min–1).
(CH2)10
H
H
Br
HO
14
Br
OH
BBr3 in CH2Cl2
6
room temp.
for 0.5 h
(83%)
(CH2)10
O
9b
8
Preparation of 1,10-bis(4-methoxyphenyl)decane (2)
3
4b
To a solution of 9.52 g (0.39 mol) of magnesium and a
small amount of iodine in THF (10 mL) was added a solution
of 4-bromoanisole (1) (33.7 g, 0.18 mol) in THF (40 mL)
and the mixture was refluxed for 12 h. To a solution of
1,10-dibromodecane (18 g, 60 mmol) and CuBr (2.0 g,
14 mmol) in HMPA (10 mL) was added dropwise a solution
of 4-methoxyphenylmagnesium bromide with gentle reflux-
ing. After the reaction mixture was refluxed for an additional
24 h, it was quenched with a 10% aqueous ammonium chlor-
ide solution and extracted with CH2Cl2 (100 mL × 3). After
the combined CH2Cl2 extracts were dried over Na2SO4, the
solvent was evaporated in vacuo, and the residue was washed
with methanol (100 mL) to afford 19 g of crude 2 as a color-
less solid. Recrystallization from hexane gave 2 (17.5 g,
O
15
of the intramolecularly cyclized nine-membered intermediate
B to afford 13 during the demethylation of 7 with BBr3.
Conclusions
We have demonstrated a convenient preparation of 4,22-
dimethoxy[2.10]MCP-1-yne (7) and conversion to a novel
[10]benzofurochromenophane (13) by treatment with BBr3
in CH2Cl2 at room temperature via demethylation and a
successive intramolecular cyclization reaction. Interestingly,
similar treatment of a mixture of the corresponding meso-
and dl-1,2-dibromo-4,22-dimethoxy[2.10]MCP (6) with
BBr3 in CH2Cl2 under these same conditions afforded cis-
4b,9b-dihydro[10]benzofuro[3,2-b]benzofuranophane (15) in
83% yield by double intramolecular cyclization. Further
studies on the chemical properties of [10](2,9)-5a,11a-
benzofuro-5a-bora-11-bromochromenophane 13 and cis-4b,9b-
dihydro[10]benzofuro[3,2-b]benzofuranophane 15 are now
in progress.
1
82%) as colorless prisms, mp 64–65 °C. H NMR (CDCl3)
d: 1.27 (broad s, 12H, CH2), 1.54 (s, 4H, CH2), 2.54–2.59
(m, 4H, CH2), 3.78 (s, 6H, OMe), 6.82 (d, J = 8.8 Hz, 4H,
Ar–H), 7.08 (d, J = 8.8 Hz, 4H, Ar–H). MS m/z (%): 354
(M+). Anal. calcd for C24H34O2 (354.53): C 81.31, H 9.67;
found: C 81.42, H 9.54.
Preparation of 1,10-bis(3-formyl-4-methoxyphenyl)decane
(3)
To a solution of 1,10-bis(4-methoxyphenyl)decane (2,
7.08 g, 20 mmol) and Cl2CHOCH3 (4.86 mL, 56 mmol) in
CH2Cl2 (40 mL) was added a solution of TiCl4 (6.7 mL,
Experimental
All melting points were uncorrected. Proton nuclear mag-
Published by NRC Research Press

446
Can. J. Chem. Vol. 90, 2012
Scheme 9. Proposed reaction mechanism for BBr3-induced transformation from 6 to 15.
(CH2)10
Br
Br
-H+
H+
BBr3
14
6
-MeBr
H
H
OH
:
HO
D
(CH2)10
(CH2)10
Br
H
:O
Br
H
H+
H
rotation
O
O
H
OH
H
F
E
(CH2)10
H
H+
H
O+
15
O
H
G
61 mmol) in CH2Cl2 (40 mL) at 0 °C. After the reaction
mixture was stirred at room temperature (rt) for 3 h, it was
poured into a large amount of ice water (200 mL) and ex-
tracted with CH2Cl2 (100 mL × 2). The combined extracts
were washed with water, dried with Na2SO4, and concen-
trated. The residue was chromatographed over silica gel
(Wako C-300, 500 g) with hexane – ethylacetate (4:1) as elu-
ent to give crude 3. Recrystallization from hexane gave
6.82 g (83%) of 1,10-bis(3-formyl-4-methoxyphenyl)decane
hexane afforded (E)-4 (2.28 g, 52%). The filtrate was con-
densed in vacuo to afford (Z)-4 (1.83 g, 42%) as a colorless
oil. The material obtained from the ethyl acetate eluent was
recrystallized from hexane and afforded 5 (190 mg, 4%) as
colorless prisms.
(E)-4,22-Dimethoxy[2.10]metacyclophan-1-ene ((E)-4)
(E)-4 was obtained as colorless prisms (hexane), mp 102–
1
103 °C. H NMR (CDCl3) d: 1.46 (broad s, 12H, CH2), 1.69
(3) as colorless prisms, mp 63–64 °C. IR (KBr, cm–1) nmax
:
(broad s, 4H, CH2), 2.55–2.67 (m, 4H, CH2), 3.89 (s, 6H,
OMe), 6.79 (d, J = 8.4 Hz, 2H, ArH), 6.98 (dd, J = 2.4,
8.4 Hz, 2H, Ar–H), 7.30 (d, J = 2.4 Hz, 2H, Ar–H), 7.36 (s,
2H, =CH). 13C NMR (CDCl3) d: 26.87, 28.35, 29.27, 29.99,
31.75, 55.47, 110.74, 126.62, 128.33, 128.53, 129.62,
133.41, 155.30. MS m/z (%): 378 (M+). Anal. calcd for
C26H34O2 (378.55): C 82.49, H 9.05; found: C 82.41, H 8.99.
1
1683 (C=O). H NMR (CDCl3) d: 1.26 (broad s, 12H, CH2),
1.55 (s, 4H, CH2), 2.54–2.59 (m, 4H, CH2), 3.91 (s, 6H,
OMe), 6.10 (d, J = 8.4 Hz, 2H, ArH), 7.36 (dd, J = 2.1,
8.4 Hz, 2H, ArH), 7.63 (d, J = 2.1 Hz, 2H, Ar–H), 10.4 (s,
2H, CHO). MS m/z (%): 410 (M+). Anal. calcd for C26H34O4
(410.56): C 76.06, H 8.35; found: C 76.14, H 8.27.
(Z)-4,22-Dimethoxy[2.10]metacyclophan-1-ene ((Z)-4)
(Z)-4 was obtained as a colorless oil. H NMR (CDCl3) d:
McMurry coupling reaction of 3
1
The McMurry reagent was prepared from TiCl4
(13.75 mL, 125 mmol) and Zn powder (18 g, 275 mmol) in
dry THF (500 mL), under nitrogen. A solution of 1,10-bis(3-
formyl-4-methoxyphenyl)decane (3, 4.72 g, 11.5 mmol) in
dry THF (250 mL) was added within 60 h to the black mix-
ture of the McMurry reagent by using a high-dilution techni-
que with continuous refluxing and stirring. The reaction
mixture was refluxed for an additional 8 h, cooled to rt, and
hydrolysed with aqueous 10% K2CO3 (500 mL) at 0 °C. The
reaction mixture was extracted with CH2Cl2 (300 mL × 3).
The combined extracts were washed with water, dried with
Na2SO4, and concentrated. The residue was chromatographed
over silica gel (Wako C-300, 500 g) with hexane – ethyl ace-
tate (4:1) and ethyl acetate as eluents to give a mixture of
(E)-4 and (Z)-4 as a colorless oil and 5 as a colorless solid.
Recrystallization of hexane – ethyl acetate (4:1) eluents from
1.26 (m, 12H, CH2), 1.43 (m, 4H, CH2), 2.33–2.42 (m, 4H,
CH2), 3.69 (s, 6H, OMe), 6.70 (s, 2H, =CH), 6.76 (d, J =
8.4 Hz, 2H, Ar–H), 6.98 (dd, J = 2.4, 8.4 Hz, 2H, Ar–H),
7.03 (d, J = 2.4 Hz, 2H, Ar–H). MS m/z (%): 378 (M+).
Anal. calcd for C26H34O2 (378.55): C 82.49, H 9.05; found:
C 82.64, H 9.07.
1,2-Dihydroxy-4,22-dimethoxy[2.10]metacyclophane (5)
Compound 5 was obtained as colorless prisms (hexane),
1
mp 116–117 °C. H NMR (CDCl3) d: 1.24 (broad s, 12H,
CH2), 1.42–1.46 (m, 4H, CH2), 2.37–2.44 (m, 4H, CH2),
3.53 (s, 6H, OMe), 3.86 (d, J = 2.1 Hz, 2H, OH), 4.81 (d,
J = 2.1 Hz, 2H, CH), 6.61 (d, J = 8.1 Hz, 2H, Ar–H), 6.72
(d, J = 2.4 Hz, 2H, Ar–H), 6.95 (dd, J = 2.4, 8.1 Hz, 2H,
Ar–H). 13C NMR (CDCl3) d: 26.3, 26.5, 29.7, 34.5, 55.2,
Published by NRC Research Press

Uchikawa et al.
447
109.8 100.1, 127.3, 127.8, 128.1, 130.3, 155.2. MS m/z (%):
394 (M+ – H2O). Anal. calcd for C26H36O4 (412.57): C
75.69, H 8.8; found: C 75.73, H 8.78.
(500 mL) at 0 °C. The reaction mixture was extracted with
CH2Cl2 (300 mL × 3). The combined extracts were washed
with water, dried with Na2SO4, and concentrated. The residue
was treated with hexane (100 mL) to afford a colorless solid.
Recrystallization from hexane afforded (E)-1,2-bis(2-methoxy-
5-methylphenyl)ethene ((E)-9, 3.15 g, 70%) as colorless
Bromination of (Z)-4 with BTMA Br3
To a solution of (Z)-4 (200 mg, 0.53 mmol) in CH2Cl2
(20 mL) was added BTMA Br3 (220 mg, 0.58 mmol) at rt.
After the reaction mixture was stirred at rt for 5 min, it was
poured into a large amount of ice water (50 mL) and ex-
tracted with CH2Cl2 (50 mL × 2). The combined extracts
were washed with water, dried with Na2SO4, and concen-
trated. The residue was recrystallized from hexane and gave
228 mg (80%) of a mixture of 1-endo-bromo-2-exo-bromo-
4,22-dimethoxy[2.10]metacyclophane (rac-6) and 1,2-di-endo-
bromo-4,22-dimethoxy[2.10]-metacyclophane (meso-6) in a
ratio of 55:45 as colorless prisms, mp 148–149 °C. 1H
NMR (CDCl3) (rac-6) d: 1.36 (broad s, 12H, CH2), 1.45
(m, 4H, CH2), 2.41–2.46 (m, 4H, CH2), 3.73 (s, 3H,
OMe), 3.78 (s, 3H, OMe), 5.64 (d, J = 10.2 Hz, 1H, CH),
6.60 (d, J = 7.8 Hz, 1H, Ar–H), 6.70 (d, J = 10.2 Hz, 1H,
CH), 6.87–6.92 (m, 5H, Ar–H); meso-6 d: 1.36 (broad s,
12H, CH2), 1.45 (m, 4H, CH2), 2.41–2.46 (m, 4H, CH2),
3.91 (s, 6H, OMe), 6.36 (s, 2H, CH), 6.65 (d, J = 7.8 Hz,
2H, ArH), 6.89 (dd, J = 1.2, 7.8 Hz, 2H, Ar–H), 7.08 (d,
J = 1.2 Hz, 2H, Ar–H). MS m/z (%): 536, 538, 540 (M+).
Anal. calcd for C26H34Br2O2 (538.35): C 58.01, H 6.37;
found: C 58.27, H 6.42.
1
prisms, mp 123–125 °C. H NMR (CDCl3) d: 2.34 (s, 6H,
CH3), 3.85 (s, 6H, OMe), 6.78 (d, J = 8.3 Hz, 2H, Ar–H),
7.02 (dd, J = 2.2, 8.3 Hz, 2H, Ar–H), 7.42 (s, 2H, =CH),
7.45 (d, J = 2.2 Hz, 2H, ArH). 13C NMR (CDCl3) d: 20.6,
55.6, 110.8, 123.1, 123.3, 126.9, 128.8, 129.8, 154.7. MS
m/z (%): 268 (M+). Anal. calcd for C18H20O2 (268.36): C
80.56, H 7.51; found: C 80.41, H 7.69.
Bromination of (E)-9 with BTMA Br3
To a solution of (E)-9 (1.0 g, 3.73 mmol) in CH2Cl2
(100 mL) was added BTMA Br3 (1.74 g, 4.46 mmol) at rt.
After the reaction mixture was stirred at rt for 5 min, it was
poured into a large amount of ice water (300 mL) and ex-
tracted with CH2Cl2 (100 mL × 2). The combined extracts
were washed with water, dried with Na2SO4, and concen-
trated. The residue was treated with hexane (100 mL) to af-
ford a colorless solid. Recrystallization from hexane afforded
1,2-bromo-1,2-bis(2-methoxy-5-methylphenyl)-ethane
(10,
1
1.35 g, 84%) as colorless prisms, mp 146–148 °C. H NMR
(CDCl3) d: 2.18 (s, 6H, CH3), 3.74 (s, 6H, OMe), 6.11 (s,
2H, CH), 6.52 (d, J = 8.1 Hz, 2H, Ar–H), 7.12 (dd, J = 2.0,
8.1 Hz, 2H, Ar–H), 7.38 (d, J = 2.0 Hz, 2H, Ar–H). MS m/z
(%): 426, 428, 430 (M+). Anal. calcd for C18H20Br2O2
(428.17): C 50.61, H 4.76; found: C 50.49, H 4.71.
Similar treatment of (E)-4 with BTMA Br3 under the same
conditions as noted in the previous paragraph afforded a mix-
ture of rac-6 and meso-6 in 91% yield in a ratio of 55:45 as
colorless prisms.
Dehydrobromination of 10 with KOBu-t
Dehydrobromination of 6 with KOBu-t
To a solution of a mixture of 10 (680 mg, 1.59 mmol) in
HOBu-t (68 mL) was added KOBu-t (1.78 g, 15.9 mmol) at
rt. After the reaction mixture was stirred at 80 °C for 24 h, it
was poured into a large amount of ice water (50 mL) and ex-
tracted with CH2Cl2 (100 mL × 2). The combined extracts
were washed with water, dried with Na2SO4, and concen-
trated. The residue was chromatographed over silica gel
(Wako C-300, 500 g) with hexane as eluents to give a color-
less solid. Recrystallization from hexane afforded 1,2-bis(2-
methoxy-5-methylphenyl)ethyne (11, 223 mg, 53%) as colorless
To a solution of a mixture of meso- and dl-6 (180 mg,
0.33 mmol) in HOBu-t (24 mL) was added KOBu-t (1.18 g,
10.5 mmol) at rt. After the reaction mixture was stirred at
80 °C for 2 h, it was poured into a large amount of ice water
(50 mL) and extracted with CH2Cl2 (100 mL × 2). The com-
bined extracts were washed with water, dried with Na2SO4,
and concentrated. The residue was recrystallized from metha-
nol and gave 89 mg (72%) of 4,22-dimethoxy[2.10]metacy-
clophan-1-yne (7) as colorless prisms, mp 113–114 °C. IR
(KBr, cm–1) nmax: 2899, 2866, 2830, 2050 (C=C), 1495,
1
prisms, mp 114–115 °C. H NMR (CDCl3) d: 2.28 (6H, s,
1
CH3), 3.89 (s, 6H, OMe), 6.78 (d, J = 8.4 Hz, 2H, ArH),
7.07 (dd, J = 2.4, 8.4 Hz, 2H, Ar–H), 7.33 (d, J = 2.2 Hz,
2H, Ar–H). 13C NMR (CDCl3) d: 20.27, 56.04, 89.69 (sp-C),
110.6, 112.46, 129.60, 130.04, 133.96, 157.86. MS m/z
(%): 266 (M+). Anal. calcd for C18H18O2 (266.34): C
81.17, H 6.81; found: C 81.03, H 6.92.
1463, 1258, 1100, 1025, 802. H NMR (CDCl3) d: 1.41 (m,
12H, CH2), 1.60–1.72 (m, 4H, CH2), 2.61–2.69 (m, 4H,
CH2), 3.89 (s, 6H, OMe), 6.78 (d, J = 8.4, 2H, Ar-H), 7.03
(dd, J = 8.4, 2.1 Hz, 2H, ArH), 7.39 (d, J = 2.1 Hz, 2H, Ar–
H). 13C NMR (CDCl3) d: 26.65, 28.31, 29.17, 29.63, 31.76,
55.76, 91.48 (sp-C), 110.68, 112.11, 130.15, 133.52, 134.80,
156.56. MS m/z (%): 376 (M+). Anal. calcd for C26H32O2
(376.53): C 76.06, H 8.57; found: C 82.87, H 8.50.
Reaction of 7 with BBr3
To a solution of 7 (60 mg, 0.16 mmol) in CH2Cl2 (6 mL)
at 0 °C was gradually added a solution of BBr3 (0.087 mL,
0.922 mmol) in (0.1 mL). After the reaction mixture was
stirred at rt for 0.5 h, it was poured into ice water (10 mL)
and then extracted with CH2Cl2 (10 mL × 3). The combined
extracts were washed with water (10 mL × 2), dried over
Na2SO4, and concentrated in vacuo to leave a residue. The
residue was chromatographed over silica gel (Wako C-300,
100 g) with hexane–CHCl3 (4:1) as eluent to give crude 13
as a colorless solid. Recrystallization from EtOH gave
McMurry coupling reaction of 8
The McMurry reagent was prepared from TiCl4 (11.0 mL,
100 mmol) and Zn powder (14.4 g, 220 mmol) in dry THF
(300 mL), under nitrogen. A solution of 2-formyl-5-methyl-
anisole (8, 5.0 g, 33.3 mmol) in dry THF (70 mL) was added
within 24 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 rt, and hydrolysed with aqueous 10% K2CO3
Published by NRC Research Press

448
Can. J. Chem. Vol. 90, 2012
[10](2,9)-5a,11a-benzofuro-5a-bora-11-bromochromenophane
Supplementary data
(13, 58 mg, 83%) as colorless prisms, mp 207–208 °C. IR
Supplementary data are available with the article through
the journal Web site http://nrcresearchpress.com/doi/suppl/
10.1139/v2012-014. CCDC 779075 and 819676 contain the
X-ray data in CIF format for this manuscript. These data can
be obtained, free of charge, via http://www.ccdc.cam.ac.uk/
products/csd/request (Or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: 144 1223 33603; or e-mail: deposit@ccdc.cam.ac.
uk.
1
(KBr, cm–1) nmax: 2900, 2354, 1539, 1502, 1454. H NMR
(CDCl3) d: 1.27–1.35 (m, 12H, CH2), 1.60 (s, 4H, CH2),
2.64–2.67 (m, 2H, CH2), 2.76–2.79 (m, 2H, CH2), 6.84 (d,
J = 8.4, 1H, Ar–H), 6.86 (d, J = 2.4 Hz, 1H, Ar–H), 7.01
(dd, J = 2.4, 8.4 Hz, 1H, Ar–H), 7.18 (d, J = 8.4 Hz, 1H,
Ar–H), 7.23 (dd, J = 1.2, 8.4 Hz, 1H, Ar–H), 7.95 (d, J =
1.2 Hz, 1H, ArH). MS m/z (%): 435, 437 (M+). Anal. calcd
for C24H26BBrO2 (437.19): C 65.94, H 5.99; found: C
65.63, H 6.06.
Acknowledgement
Reaction of 6 with BBr3
To a solution of 6 (60 mg, 0.11 mmol) in CH2Cl2 (6 mL)
at 0 °C was gradually added a solution of BBr3 (0.087 mL,
0.922 mmol) in CH2Cl2 (0.1 mL). After the reaction mixture
was stirred at rt for 0.5 h, it was poured into ice water
(10 mL) and then extracted with CH2Cl2 (10 mL × 3). The
combined extracts were washed with water (10 mL × 2),
dried over Na2SO4, and concentrated in vacuo to leave a res-
idue. The residue was chromatographed over silica gel (Wako
C-300, 100 g) with hexane–CHCl3 (4:1) as eluent to give
crude 15 as a colorless solid. Recrystallization from EtOH
gave cis-4b,9b-dihydro[10]benzofuro[3,2-b]benzofuranophane
This work was performed under the Cooperative Research
Program of the Network Joint Research Center for Materials
and Devices, Institute for Materials Chemistry and Engineer-
ing, Kyushu University, Kasuga, Japan.
References
(1) Keehn, P. M., Rosenfield, S. M. Eds. Cyclophanes; Academic
Press: New York, 1983; Vol. 1, Chapter 6, pp 428.
(2) Vögtle, F. Cyclophane Chemistry; Wiley: Chichester, UK,
1993.
(3) Gleiter, R.; Hopf, H. Modern Cyclophane Chemistry; Wiley-
1
(15, 32 mg, 83%) as colorless prisms, mp 163–164 °C. H
VCH, Weinheim, Germany, 2004.
NMR (CDCl3) d: 0.25–1.26 (m, 16H, CH2), 2.58–2.64 (m,
4H, CH2), 6.08 (s, 2H, CH), 6.99 (dd, J = 8.1, 2.4 Hz, 2H,
Ar–H), 7.00 (d, J = 8.1 Hz, 2H, Ar–H), 7.42 (d, J = 2.4 Hz,
2H, Ar–H). MS m/z (%): 348 (M+). Anal. calcd for C24H28O2
(348.49): C 82.72, H 8.10; found: C 82.63, H 8.03.
(4) (a) Psiorz, M.; Hopf, H. Angew. Chem. 1982, 21 (8), 623.
doi:10.1002/anie.198206231; (b) Psiorz, M.; Hopf, H. Angew.
Chem. Int. Ed. Engl. 1982, 21 (8), 623. doi:10.1002/anie.
198206231.
(5) (a) Reiser, O.; Reichow, S.; de Meijere, A. Angew. Chem.
1987, 99 (12), 1285. doi:10.1002/ange.19870991213; (b)
Reiser, O.; Reichow, S.; de Meijere, A. Angew. Chem. Int.
Ed. Engl. 1987, 26 (12), 1277. doi:10.1002/anie.198712771.
(6) (a) Wong, T.; Cheung, S. S.; Wong, H. N. C. Angew. Chem.
1988, 100 (5), 716. doi:10.1002/ange.19881000516; (b)
Wong, T.; Cheung, S. S.; Wong, H. N. C. Angew. Chem. Int.
Ed. Engl. 1988, 27 (5), 705. doi:10.1002/anie.198807051.
(7) (a) König, B.; Heinze, J.; Meerholz, K.; de Meijere, A. Angew.
Chem. 1991, 103 (10), 1350. doi:10.1002/ange.19911031017;
(b) König, B.; Heinze, J.; Meerholz, K.; de Meijere, A. Angew.
Chem. Int. Ed. Engl. 1991, 30 (10), 1361. doi:10.1002/anie.
199113611.
Crystallographic data for (E)-4 and 7
Crystal data for (E)-4
C26H34O2, M = 378.55, monoclinic, P121/a, a = 17.192(7),
b = 6.489(3), c = 39.947(17) Å, V = 4357(3) Å3, b =
102.1256(11), Z = 8, Dc = 1.154 g cm–3, m (Mo Ka) =
0.071 mm–1, T = 123.1 K, colourless prisms; 9519 reflec-
tions measured on a Rigaku Saturn CCD diffractometer, of
which 6779 were independent, data corrected for absorption
on the basis of symmetry equivalent and repeated data (min
and max transmission factors: 0.849 and 0.998) and Lp ef-
fects, Rint = 0.087, structure solved by direct methods
(Sir2002), F2 refinement, R1 = 0.156 for 6779 data with
F2 > 2s(F2), wR2 = 0.4034 for all data, 8360 parameters.
(8) Chan, C. W.; Wong, H. C. J. Am. Chem. Soc. 1988, 110 (2),
462. doi:10.1021/ja00210a025.
(9) Ramming, M.; Gleiter, R. J. Org. Chem. 1997, 62 (17), 5821.
doi:10.1021/jo970327r.
(10) Kawase, T.; Ueda, N.; Oda, M. Tetrahedron Lett. 1997, 38
(38), 6681. doi:10.1016/S0040-4039(97)01564-5.
(11) Utsumi, K.; Kawase, T.; Oda, M. Chem. Lett. 2003, 32 (4),
412. doi:10.1246/cl.2003.412.
Crystal data for 7
C26H32O2, M = 376.52, monoclinic, P21/a, a = 16.7234(14),
b = 6.422(4), c = 41.504(9) Å, V = 4370(3) Å3, b =
101.363(14), Z = 8, Dc = 1.145 g cm–3, m (Cu Ka) =
0.543 mm–1, T = 113 K, colourless prisms; 53 123 reflec-
tions measured on a Rigaku Saturn CCD diffractometer, of
which 7933 were independent, data corrected for absorption
on the basis of symmetry equivalent and repeated data (min
and max transmission factors: 0.750 and 0.947) and Lp ef-
fects, Rint = 0.044, structure solved by direct methods
(Sir2002), F2 refinement, R1 = 0.0577 for 7933 data with
F2 > 2s(F2), wR2 = 0.1814 for all data, 569 parameters
(crystallographic data (excluding structure factors) for the
structures in this paper can be found in the Supplementary
data).
(12) Kawase, T. Synlett 2007, 2007 (17), 2609. doi:10.1055/s-2007-
991078.
(13) Yamato, T.; Fujita, K.; Abe, T.; Tsuzuki, H. New J. Chem.
2001, 25 (5), 728. doi:10.1039/b010205i.
(14) Fukazawa, A.; Yamaguchi, S. Chem. Asian J. 2009, 4 (9),
1386. doi:10.1002/asia.200900179.
(15) Fukazawa, A.; Yamada, H.; Yamaguchi, S. Angew. Chem. Int.
Ed. 2008, 47 (30), 5582. doi:10.1002/anie.200801834.
(16) Wakamiya, A.; Mori, K.; Araki, T.; Yamaguchi, S. J. Am.
Chem. Soc. 2009, 131 (31), 10850. doi:10.1021/ja905007s.
(17) Fukazawa, A.; Yamada, H.; Sasaki, Y.; Akiyama, S.;
Published by NRC Research Press

Uchikawa et al.
Yamaguchi, S. Chem. Asian J. 2010, 5 (3), 466. doi:10.1002/
449
(35) Yamato, T.; Matsumoto, J.; Ide, S.; Suehiro, K.; Tashiro, M. J.
Chem. Res. (S) 1993, 394.
asia.200900517.
(18) Iida, A.; Yamaguchi, S. J. Am. Chem. Soc. 2011, 133 (18),
(36) Yamato, T.; Fujita, K.; Okuyama, K.; Tsuzuki, H. New J.
Chem. 2000, 24 (4), 221. doi:10.1039/b001145m.
(37) Yamato, T.; Fujita, K.; Futatsuki, K.; Tsuzuki, H. Can. J.
Chem. 2000, 78 (8), 1089. doi:10.1139/v00-110.
(38) Yamato, T.; Fujita, K.; Tsuzuki, H. J. Chem. Soc., Perkin
Trans. 1 2001, (17): 2089. doi:10.1039/b010075g.
(39) Yamato, T.; Miyamoto, S.; Hironaka, T.; Miura, Y. Org. Lett.
2005, 7 (1), 3. doi:10.1021/ol0483403.
(40) Yamato, T.; Hironaka, T.; Shiino, M.; Saisyo, T.; Miyamoto, S.
J. Chem. Res. 2006, 2006 (2), 110. doi:10.3184/
030823406776330990.
(41) Yamato, T.; Okabe, R.; Miyamoto, S.; Miyazaki, M. J. Chem.
Res. 2006, 2006 (9), 593. doi:10.3184/030823406778521509.
(42) Saisyo, T.; Hironaka, T.; Shiino, M.; Yamato, T. J. Chem. Res.
2006, 2006 (10), 661. doi:10.3184/030823406779173659.
(43) Saisyo, T.; Shiino, M.; Shimizu, T.; Paudel, A.; Yamato, T. J.
Chem. Res. 2008, 2008 (8), 479. doi:10.3184/
030823408X338701.
6952. doi:10.1021/ja2019977.
(19) Yamato, T.; Matsumoto, J.-I.; Ide, S.; Suehiro, K.; Kobayashi,
K.; Tashiro, M. Chem. Ber. 1993, 126 (2), 447. doi:10.1002/
cber.19931260223.
(20) (a) Yamato, T.; Sato, M.; Noda, K.; Matsumoto, J.; Tashiro, M.
J. Chem. Res. (S) 1993, 10, 394; (b) Yamato, T.; Sato, M.;
Noda, K.; Matsumoto, J.; Tashiro, M. J. Chem. Res. (M) 1993,
10, 2601.
(21) Yamato, T.; Matsumoto, J.; Ide, S.; Tokuhisa, K.; Suehiro, K.;
Tashiro, M. J. Org. Chem. 1992, 57 (19), 5243. doi:10.1021/
jo00045a044.
(22) Yamato, T.; Matsumoto, J.-I.; Tokuhisa, K.; Kajihara, M.;
Suehiro, K.; Tashiro, M. Chem. Ber. 1992, 125 (11), 2443.
doi:10.1002/cber.19921251116.
(23) Yamato, T.; Matsumoto, J.; Sato, M.; Noda, K.; Tashiro, M. J.
Chem. Soc., Perkin Trans. 1 1995, (10): 1299. doi:10.1039/
p19950001299.
(24) Yamato, T.; Matsumoto, J.; Fujita, K. J. Chem. Soc., Perkin
Trans. 1 1998, (1): 123. doi:10.1039/a704105e.
(25) McMurry, J. E.; Fleming, M. P.; Kees, K. L.; Krepski, L. R. J.
Org. Chem. 1978, 43 (17), 3255. doi:10.1021/jo00411a002.
(26) McMurry, J. E. Acc. Chem. Res. 1983, 16 (11), 405. doi:10.
1021/ar00095a003.
(27) McMurry, J. E.; Haley, G. J.; Matz, J. R.; Clardy, J. C.; Van
Duyne, G.; Gleiter, R.; Schaefer, W.; White, D. H. J. Am.
Chem. Soc. 1984, 106 (17), 5018. doi:10.1021/ja00329a071.
(28) McMurry, J. E. Chem. Rev. 1989, 89 (7), 1513. doi:10.1021/
cr00097a007.
(44) Merz, A.; Karl, A.; Futterer, T.; Stacherdinger, N.; Schneider,
O.; Lex, J.; Luboch, E.; Biernat, J. F. Liebigs Ann. Chem.
1994, 1994 (12), 1199. doi:10.1002/jlac.199419941211.
(45) Tashiro, M.; Yamato, T. J. Org. Chem. 1981, 46 (22), 4556.
doi:10.1021/jo00335a047.
(46) Tashiro, M.; Yamato, T. J. Org. Chem. 1983, 48 (9), 1461.
doi:10.1021/jo00157a015.
(47) Kajigaeshi, S.; Kakinami, T.; Tokiyama, H.; Hirakawa, T.;
Okamoto, T. Chem. Lett. 1987, 16 (4), 627. doi:10.1246/cl.
1987.627.
(48) (a) Kloster-Jensen, E.; Wirz, J. Angew. Chem. 1973, 85 (16),
723. doi:10.1002/ange.19730851608;; (b) Kloster-Jensen, E.;
Wirz, J. Angew. Chem. Int. Ed. Engl. 1973, 12 (8), 671. doi:10.
1002/anie.197306711.
(49) Olah, G. A.; Narang, S. C.; Gupta, B. G. B.; Malhotra, R. J.
Org. Chem. 1979, 44 (8), 1247. doi:10.1021/jo01322a012.
(50) Olah, G. A.; Narang, S. C.; Gupta, B. G. B.; Malhotra, R.
Synthesis 1979, 1979 (01), 61. doi:10.1055/s-1979-28558.
(51) Yamato, T.; Matsumoto, J.; Tashiro, M. J. Chem. Res. 1994,
178.
(29) Mitchell, R. H.; Weerawarna, S. A. Tetrahedron Lett. 1986, 27
(4), 453. doi:10.1016/S0040-4039(00)85503-3.
(30) Tanner, D.; Wennerström, O.; Chattopadhyaya, J.; Carlberg, G.
E.; Sterner, O.; Wickberg, B. Acta Chem. Scand. Ser. B. 1983,
37b, 693. doi:10.3891/acta.chem.scand.37b-0693.
(31) Hopf, H.; Mlynek, C. J. Org. Chem. 1990, 55 (4), 1361.
doi:10.1021/jo00291a052.
(32) Grützmacher, H.-F.; Neumann, E. Chem. Ber. 1993, 126 (6),
1495. doi:10.1002/cber.19931260635.
(33) Shukla, R.; Brody, D. M.; Lindeman, S. V.; Rathore, R. J. Org.
Chem. 2006, 71 (16), 6124. doi:10.1021/jo060817w.
(34) Debroy, P.; Lindeman, S. V.; Rathore, R. J. Org. Chem. 2009,
74 (5), 2080. doi:10.1021/jo802579f.
(52) Yamato, T.; Saruwatari, Y.; Yasumatsu, M.; Ide, S. Eur. J. Org.
Chem. 1998, 1998 (2), 309. doi:10.1002/(SICI)1099-0690
(199802)1998:2<309::AID-EJOC309>3.0.CO;2-6.
Published by NRC Research Press