Synthesis and Structures of a Series of Bulky "Rind-Br" Based on a Rigid Fused-Ring s-Hydrindacene Skeleton

Article abstract of DOI:10.1246/bcsj.20110090

A series of octa-R-substituted bromo-s-hydrindacenes, "Rind-Br," have been synthesized by a sequence of the Lewis acid catalyzed intramolecular FriedelCrafts reaction, bromination and vice versa. Their structural features and physical properties depend on

Full text of DOI:10.1246/bcsj.20110090

1178 Bull. Chem. Soc. Jpn. Vol. 84, No. 11, 1178-1191 (2011)
© 2011 The Chemical Society of Japan
BCSJ Award Article
Synthesis and Structures of a Series of Bulky “Rind-Br” Based
on a Rigid Fused-Ring s-Hydrindacene Skeleton
Tsukasa Matsuo,*1 Katsunori Suzuki,1 Tomohide Fukawa,1 Baolin Li,1 Mikinao Ito,1
Yoshiaki Shoji,1 Takashi Otani,1 Liangchun Li,1 Megumi Kobayashi,1 Makoto Hachiya,1
the late Yoshiyuki Tahara,1 Daisuke Hashizume,2 Takeo Fukunaga,2 Aiko Fukazawa,3
Yongming Li,3 Hayato Tsuji,3 and Kohei Tamao*1,3
1Functional Elemento-Organic Chemistry Unit, RIKEN Advanced Science Institute,
2-1 Hirosawa, Wako, Saitama 351-0198
2Advanced Technology Support Division, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198
3International Research Center for Elements Science (IRCELS), Institute for Chemical Research, Kyoto University,
Uji, Kyoto 611-0011
Received March 24, 2011; E-mail: matsuo@riken.jp, tamao@riken.jp
A series of octa-R-substituted bromo-s-hydrindacenes, “Rind-Br,” have been synthesized by a sequence of the Lewis
acid catalyzed intramolecular Friedel-Crafts reaction, bromination and vice versa. Their structural features and physical
properties depend on the eight R-substituents at the four benzylic positions on the s-hydrindacenyl skeleton. The
molecular structures of the Rind-Br have been confirmed by X-ray crystallography, indicating the unique structural
diversities of the bulky Rind groups.
The development of substituents or ligands that play
supporting roles in both the fundamental and applied chem-
istries, has been the subject of intense interest for many years.
Since the discovery of the stable silene (R2Si=CR2),1 disilene
(R2Si=SiR2),2 and diphosphene (RP=PR)3 were reported
in 1981 by introducing a concept of steric protection with
bulky substituents, a variety of unsaturated compounds of the
heavier main group elements have successfully been isolated
by many leading scientists using their own, newly developed
bulky ligands.4-12 For example, in organosilicon chemistry,
many unsaturated compounds, such as silaaromatics (silaben-
zene),13-22 trisilaallene (R2Si=Si=SiR2),23-27 and disilyne
(RSi¸SiR),28-34 have been synthesized by taking advantage
of the steric protection by the appropriate bulky groups.35
The bulky protecting groups so far developed can be
categorized into three types, i.e., aryl,2,3,13-19,21,22,34 alkyl,1,23-27
and silyl20,28-33 groups. Among them, the bulky aryl groups
have been the most widely used in this chemistry. The bulky
aryl groups can also be further categorized into two types, i.e.,
2,4,6-trialkylphenyl groups and 2,6-diarylphenyl groups. Some
of their characteristic features are summarized as follows.
Typical 2,4,6-trialkylphenyl groups include the 2,4,6-tri-
methylphenyl (Mes),2 2,4,6-tri(isopropyl)phenyl (Tip), 2,4,6-
tri(tert-butyl)phenyl (Mes*),3 2,4,6-tris[bis(trimethylsilyl)-
methyl]phenyl (Tbt), and 2,6-bis[bis(trimethylsilyl)methyl]-4-
[tris(trimethylsilyl)methyl]phenyl (Bbt)13-19,21,22,34 groups. The
steric bulkiness of these aryl groups increases with an increase
in the size of the ortho alkyl substituents in the following order:
methyl (Mes) < isopropyl (Tip) < tert-butyl (Mes*); the Tbt
and Bbt groups seem to be bulkier. Among the 2,6-diaryl-
phenyl groups, the 2,6-bis(2,6-dialkylphenyl)phenyl groups
have proven to be widely useful to stabilize a reactive low-
coordinated atom center.36-48 What is the most significant
difference between these two series? The difference resides in
the ease of the rotation around the C-C bond between the core-
benzene ring carbon and the substituent carbon atom. Thus,
in the 2,4,6-trialkylphenyl series, free-rotation about the C-C
bond is possible in principle (Figure 1, A), while in the 2,6-
diarylphenyl cases, especially in the 2,6-bis(2,6-dialkylphen-
yl)phenyl groups, the hindered-rotation about the C-C bond is
caused by the ortho-substituted biphenyl unit (Figure 1, B).
The free-rotation in the former case might cause interference
in the space necessary for the particular substituent at the C1
position on the core phenyl group. The hindered-rotation in the
latter case partially guarantees the space for the substituent,
thus increasing the overall protecting ability which includes the
lowered probability of intramolecular quenching reactions.
We envisioned that the freeze-rotation in certain rigid fused-
ring aromatic systems would perfectly guarantee the space for
the substituent (Figure 1, C). One example was previously
Published on the web October 29, 2011; doi:10.1246/bcsj.20110090

T. Matsuo et al.
Bull. Chem. Soc. Jpn. Vol. 84, No. 11 (2011) 1179
eight substituents on the benzylic positions (R1, R2, R3, and R4),
we abbreviated them as “Rind” groups, where R denotes the
initial of the substituents as follows: M (methyl), E (ethyl),
P (propyl), B (butyl), P5 (pentyl), H (hexyl), H7 (heptyl),
O (octyl), and Ph (phenyl). For example, the octamethyl-s-
hydrindacenyl group (R1 = R2 = R3 = R4 = Me) was abbrevi-
ated as the Mind group. (2) When the peripheral substituents
(R1 and R2) are different from the proximate substituents
(R3 and R4), we abbreviated them as “RR¤ind” groups, where
R and R¤ denote the peripheral and proximate substituents,
respectively. For example, an EMind group has the peripheral
ethyl substituents and the proximate methyl substituents
(R1 = R2 = Et, R3 = R4 = Me). (3) When the s-hydrindacenyl
groups assume a cross-type arrangement of the substituents, we
put an “x” ahead of RR¤ind as “xRR¤ind” groups, where the
R substituents are smaller than the R¤ substituents. For example,
an xMEind group has the substituent arrangement of R1 =
R4 = Me, R2 = R3 = Et. (4) When the s-hydrindacenyl groups
have a spiro-type connection at the benzylic positions, we put a
superscript “s” on R as “sR,” where R denotes the spiro rings.
For example, an MsFluind group has two fluorene rings at the
proximate benzylic positions in a spiro fashion.
Figure 1. Three types of bulky aryl groups: 2,4,6-trialkyl-
phenyl groups (A), 2,6-bis(2,6-dialkylphenyl)phenyl
groups (B), and octa-R-substituted fused-ring aryl groups
(C).
In this paper, monobromo and para-dibromo Rind deriva-
tives are expediently represented as “Rind-Br” and “Br-Rind-
Br,” respectively.
Summary of the Synthetic Routes and Characteristic
Features of a Series of Rind-Br.
A series of Rind-Br
prepared in this study were categorized into three regioisomers,
for which we developed three synthetic routes, as summarized
in Scheme 1. All of them involve a sequence of intramolecular
double Friedel-Crafts cyclization reactions, bromination and
vice versa. In Route 1, a four-R-substituted meta-bisbenzylic
chloride was cyclized with a 1,1-dialkylethene CH2=CR¤2
followed by bromination. Since the bromination preferentially
proceeds on the less hindered side, this route can be used
only for the cases R = R¤ and R > R¤. Route 2, involving the
bromination-cyclization sequence, can be used even for the
case of R < R¤. Thus, a meta-brominated precursor is subjected
to the Friedel-Crafts cyclization to selectively form the desired
product. This method is particularly effective for the case of
R = Me; the cyclization reaction becomes sluggish with longer
R groups (R ² Et). Route 2¤, starting from an ortho-brominated
precursor, would also be envisioned as an alternative route.
However, we found no reaction occurring despite many trials,
thus the precursor being recovered unchanged. The reason may
be ascribed to the fact that the formation of the benzylic cation
is significantly retarded by the ortho halogen atom, as reported
by H. C. Brown more than 50 years ago.61 Route 3 is for the
cross-type Rind-Br, starting from a para-bisbenzylic chloride.
Some significant features of the bulky Rind groups are listed
below and shown in Figure 2. (1) The Rind groups are easily
prepared in quantity by the intramolecular Friedel-Crafts
reaction of olefins with readily available starting materials.
(2) A variety of R-substituents can be introduced at the benzylic
positions of the s-hydrindacenyl skeleton. (3) The steric
bulkiness of the Rind groups can be controlled by the
proximate substituents (R3 and R4). (4) The physical properties
of the Rind groups, such as solubility or crystallinity, may be
mainly attributed to the peripheral substituents (R1 and R2).
Chart 1.
reported by Yoshifuji et al.; thus the 1,1,4,4,5,5,8,8-octamethyl-
1,2,3,4,5,6,7,8-octahydroanthryl group, involving two six-
membered-ring fused phenyl groups, was used to stabilize a
diphosphene derivative.49 However, this fused ring group is
rather hard to prepare; the corresponding anthracene derivative
is obtained as a by-product during preparation of the tri-tert-
butylbenzene. We have focused on the development of the five-
membered-ring fused 1,1,3,3,5,5,7,7-octa-R-substituted s-hy-
drindacenyl groups, called the “Rind” groups as shown in
Chart 1. The readily available Rind groups have several
advantages over the existing bulky groups, as represented
by the versatility and size-controllability by introduction of
various R-substituents at the four benzylic positions in the rigid
s-hydrindacenyl skeleton. As anticipated, we have already
found that the Rind groups can stabilize some reactive species
of boron, silicon, phosphorous, copper, etc.50-59
This report describes the synthesis and X-ray molecular
structures of a series of bulky aryl bromide “Rind-Br” based on
a rigid fused-ring s-hydrindacenyl skeleton.
Results and Discussion
Abbreviation of Rind Groups. As shown in Chart 1, we
have developed a series of octa-R-substituted s-hydrindacenyl
groups, called the “Rind” groups.60 The following abbreviations
were used. (1) When the s-hydrindacenyl groups have the same

1180 Bull. Chem. Soc. Jpn. Vol. 84, No. 11 (2011) BCSJ AWARD ARTICLE
Scheme 1. Synthetic routes to Rind-Br.
Preparation of Rind-Br, Eind-Br, and Mind-Br as the
Standard Symmetric Models. In 1981, Chang and Kennedy
reported the formation of octamethyl-s-hydrindacene, Mind-H
(R1 = R2 = R3 = R4 = Me), as an undesirable side product
but in rather high yields during the cationic polymerization
of isobutene with 1,4-bis(1-chloro-1-methylethyl)benzene
(para-cumyl chloride).66 Before that, Mind-H could be
obtained by alkylation of 1,1,3,3-tetramethylindane with 2,4-
dimethyl-2,4-pentanediol in the presence of AlCl3.67 Although
the Kennedy’s acid-catalyzed intramolecular Friedel-Crafts
reaction should be useful for the construction of the
s-hydrindacene skeleton, further experimental studies had not
been explored. After a quarter of century, we started to prepare
a series of Rind groups as new bulky protecting groups based
on Kennedy’s method.
Figure 2. Features of Rind groups.
Scheme 2 summarizes the synthetic route of Eind-Br as
the most versatile.50 1,3-Bis(1-chloro-1-ethylpropyl)benzene,
obtained from commercially available dimethyl isophthalate
in two steps by textbook methods, was allowed to react with
2 equiv of 2-ethyl-1-butene in the presence of a catalytic
amount of BCl3. The intramolecular double Friedel-Crafts
reaction smoothly proceeded at room temperature to produce
octaethyl-s-hydrindacene, Eind-H. Subsequent bromination
could be achieved under a rather forced condition, thus with
an excess amount of Br2 (ca. 8 to 10 equiv (molar ratio)) in
(EtO)3PO as the essential solvent68,69 at about 70 °C overnight.
The desired Eind-Br was obtained after recrystallization from
hexane/i-PrOH in 4 steps with a 39% overall yield. We can
now obtain more than 50 g of colorless crystals of Eind-Br at a
time by a convenient large-scale synthesis.
(5) The Rind groups have a high chemical stability due to the
full substitution at all benzylic positions. (6) The Rind groups
consisting of the rigid fused-ring framework provide a space
fitted for an appropriately designed substituent between the two
substituted benzylic moieties (vide infra); this space is only
slightly restricted by the benzylic substituents because of the
freeze-rotation fixed in the five-membered fused rings. (7) As
another unique feature, the Rind groups have the unsubstituted
para-position open for further functionalization, which would
provide potentially useful para-phenylene types of difunctional
compounds.62-65
While the two para-dibromo derivatives, Br-Rind-Br, are
described in this paper, the difunctional chemistry will be
reported in detail as a future study.

T. Matsuo et al.
Bull. Chem. Soc. Jpn. Vol. 84, No. 11 (2011) 1181
Kennedy,66 which made it difficult to isolate Mind-H. For
the bromination reaction, a mixed solvent of (EtO)3PO/hexane
was applied because of the poor solubility of Mind-H in
(EtO)3PO. In this case, a prolonged reaction time caused further
bromination of Mind-Br to give the dibromo compound, Br-
Mind-Br. Thus, the careful monitoring for the appropriate
reaction time (ca. 10 h) was essential to obtain the pure Mind-
Br in a good yield.
EMind-Br, MEind-Br, and xMEind-Br as Regioisomer
Models. The selective synthetic routes for the three possible
regioisomers containing methyl/ethyl mixed side chains are
summarized in Scheme 4. The two regioisomers, EMind-Br
and MEind-Br, were selectively prepared by the cyclization-
bromination and bromination-cyclization sequence, respective-
ly. Thus, the Friedel-Crafts reaction of 1,3-bis(1-chloro-1-
methylethyl)benzene with 2-ethyl-1-butene gave MEind-H in
48% yield. The subsequent bromination of MEind-H with Br2
at room temperature selectively took place on the methyl side
to give EMind-Br in 97% yield. This fact clearly indicated that
the methyl side is less bulky than the ethyl side.
Scheme 2. Synthesis of Eind-Br.
The MEind-Br regioisomer with the bromine atom on
the more hindered side was prepared starting from dimethyl
5-bromoisophthalate, which is commercially available or can
be obtained via the bromination of dimethyl isophthalate with
N-bromosuccinimide (NBS) in H2SO4.71 1-Bromo-3,5-bis(1-
chloro-1-methylethyl)benzene was prepared in two steps by
textbook methods. Although a prolonged reaction time (3 days)
was required for the subsequent Friedel-Crafts reaction at room
temperature, MEind-Br was successfully isolated as colorless
crystals in 60% yield.
The cross-type xMEind-Br was also prepared starting from
the commercially available 1,4-bis(1-hydroxy-1-methylethyl)-
benzene. A similar Friedel-Crafts cyclization reaction of 1,4-
bis(1-chloro-1-methylethyl)benzene with 2-ethyl-1-butene pro-
duced xMEind-H in 87% yield, followed by bromination to
cleanly give xMEind-Br in 84% yield.
Scheme 3. Synthesis of Mind-Br.
Based on the regioselectivity of the bromination, the steric
bulkiness of the Rind groups, if qualitative, increases with the
increasing size of the proximate substituents (R3 and R4) in the
following order: Mind, EMind (R3 = R4 = Me) < xMEind
(R3 = Et, R4 = Me) < MEind, Eind (R3 = R4 = Et).
Three points deserve comment. (1) For the Lewis acid
catalyzed Friedel-Crafts cyclization, we soon found that the
amount of BCl3 can be reduced to ca. 0.2 to 0.03 equiv, in
contrast to Kennedy’s original work in which an excess amount
of BCl3 was used.66 (2) We also examined the use other Lewis
acid catalysts such as AlCl3, AlBr3, and FeCl3, for the
preparation of Eind-H, but the cyclization reaction did not
cleanly proceed. The employment of the BF3 etherate catalyst
also resulted in a lower yield. Thus, BCl3 is considered as the
most effective catalyst for this Friedel-Crafts reaction at this
moment. (3) For the bromination reaction, the use of a large
excess amount of Br2 (more than 40 equiv) led to the clean
formation of the para-dibromo-s-hydrindacene derivative, Br-
Eind-Br. This compound can also be isolated as colorless
crystals.
As shown in Scheme 3, a less bulky aryl bromide Mind-
Br62,70 was also prepared similar to Eind-Br starting from the
commercially available 1,3-bis(1-hydroxy-1-methylethyl)ben-
zene. In the Friedel-Crafts reaction, the use of a moderately
excess amount of isobutene gas (ca. 4 equiv) was effective for
the formation of Mind-H. A larger excess amount of isobutene
gave rise to an increase in the polymer products as reported by
PEind-Br, BEind-Br, P5Eind-Br, and HEind-Br with a
Series of Peripheral Alkyl Chains.
For improving the
solubility, a series of Rind groups having longer alkyl chains,
i.e., propyl, butyl, pentyl, and hexyl, as the peripheral
substituents were prepared, as shown in Scheme 5. For the
introduction of the longer alkyl chains in the first step by the
Grignard reaction, diethyl ether (Et2O) was found to be better
than THF to prevent the concomitant dehydration at the
side chains. The Friedel-Crafts reactions with 2-ethyl-1-butene
in the presence of 0.5 to 0.25 equiv of BCl3, followed by
bromination afforded a mixture of regioisomers, REind-Br and
ERind-Br, in ca. 4:1 ratios. Thus, the ethyl side is somewhat
less bulky than the longer alkyl side. To improve the selectivity
of REind-Br, we examined various bromination conditions. For
example, the bromination of EP5ind-H and EHind-H with
gentle warming to about 35 °C using a large excess amount of
Br2 (ca. 20 equiv) led to a somewhat better selectivity to
generate P5Eind-Br and HEind-Br, but the formation of minor

1182 Bull. Chem. Soc. Jpn. Vol. 84, No. 11 (2011) BCSJ AWARD ARTICLE
Scheme 4. Synthesis of EMind-Br, MEind-Br, and xMEind-Br.
products, EP5ind-Br and EHind-Br, could not be suppressed
even under these conditions. However, the major products,
PEind-Br, BEind-Br, P5Eind-Br, and HEind-Br, could be
isolated as colorless crystals by recrystallization from hexane
or hexane/EtOH in 10-21% overall yields for the 4 steps. The
minor isomers, ERind-Br, could not be isolated in pure form.
Among the major products, the molecular structure of HEind-
Br has been determined by X-ray crystallography (vide infra).
While a higher solubility arises from the longer alkyl chains,
the crystallinity might be based on the rigid fused-ring
s-hydrindacene framework.
As expected, these four REind-Br have higher solubilities in
the common organic solvents with the alkyl chain extension.
For example, the solubility in hexane increases in the following
order: Eind-Br (0.03 g mL¹1) < PEind-Br (0.10 g mL¹1) μ
BEind-Br (0.10 g mL¹1) < P5Eind-Br (0.22 g mL¹1) < HEind-
Br (0.28 g mL¹1) μ MEind-Br (0.27 g mL¹1): the last is an
exception due to unknown factors.
methylenecyclohexane, respectively. It may be noted that
2-propyl-1-pentene was prepared by the nickel-catalyzed
cross-coupling reaction between 1,1-dichloroethene and
n-PrMgCl.72,73 The spiro MsHind-Br has a lower solubility in
the common solvents relative to MPind-Br, due to the higher
rigidity of the spiro-ring system (vide infra).
The Friedel-Crafts reaction with 1,1-diphenylethene com-
peted with its self-dimerization to give an indane derivative as
a side product, but the MPhind-Br was isolated as colorless
crystals in 26% yield after removal of the by-product by
Kugelrohr distillation followed by recrystallization from
acetone/hexane. The spiro compound, MsFluind-Br, in which
the s-hydrindacene skeleton is connected to the two fluorene
rings through the two quaternary carbon atoms at the benzylic
positions, was obtained by the Friedel-Crafts reaction using
dibenzofulvene in 76% yield, without the competing self-
dimerization of the latter.
Molecular Structures of Rind-Br.
The molecular
MPind-Br, MsHind-Br, MPhind-Br, and MsFluind-Br
with a Variety of Proximate Substituents. The steric effects
of the Rind groups are mainly dependent on the identity of the
proximate R-substituents. We have synthesized two pairs of
MRind-Br, consisting of two open-chain substituents and their
closed-ring spiro-type analog; one pair is MPind-Br and
MsHind-Br, and the other is MPhind-Br and MsFluind-Br. All
compounds were prepared by the bromination-cyclization
sequence starting from 1-bromo-3,5-bis(1-chloro-1-methyl-
ethyl)benzene, as shown in Scheme 6. The former two were
obtained without difficulty using 2-propyl-1-pentene and
structures of a series of bromo-s-hydrindacenes, Eind-Br,
HEind-Br, MPind-Br, MsHind-Br, MPhind-Br, and MsFluind-
Br,52 have been determined by X-ray crystallography, as shown
in Figure 3. These molecules display unique structural diver-
sities based on the rigid fused-ring s-hydrindacenyl skeleton and
the side groups, as can be seen from the space-filling models.
Their crystallographic and structural features are as follows.
Eind-Br: This molecule has a C2 symmetry in the crystal
with the twofold axis through the Br-C bond. The eight ethyl
groups are alternatively arranged in two different orientations,
i.e., the up and side directions.

T. Matsuo et al.
Bull. Chem. Soc. Jpn. Vol. 84, No. 11 (2011) 1183
Scheme 5. Synthesis of REind-Br.
HEind-Br: The four peripheral hexyl groups tend to align
perpendicular to the s-hydrindacene plane in the crystal. The
distance between the terminal carbon atoms of the two hexyl
substituents on the same benzylic position is about 13 ¡.
MPind-Br: An alignment of the proximate propyl groups
is found in the crystal. The distance between the terminal
carbon atoms of the two propyl substituents on the same
benzylic position is about 7.5 ¡. The packing diagram of the
MPind-Br indicates the existence of intermolecular C-H£³
interactions between the central benzene ring and the terminal
C-H bonds of the propyl chains (not shown in text).
MsHind-Br: The two cyclohexane rings adopt the chair
conformation with staying separated from the bromine atom.
Thus, the molecular structure is much different from that of the
MPind-Br mentioned above.
MPhind-Br: The four phenyl groups are oriented not in the
C2 symmetric, but in nearly the Cs symmetric structure with a
mirror plane perpendicular to the central benzene ring in the
crystal. The distances between the bromine atom and the
closest ipso-carbon atoms of the phenyl groups are 3.230 and
3.263 ¡.
MsFluind-Br: The bromine atom is sandwiched between
the two fluorene planes connected to the s-hydrindacene
skeleton. The atomic distances between the bromine atom
and the closest aromatic carbon atoms in the five-membered
rings of the fluorenyl groups are 3.305-3.549 ¡, somewhat
longer than those in the MPhind-Br.
Scheme 6. Synthesis of MRind-Br.
As shown in the top and front views of the space-filling
models of Rind-Br, the steric environment around the bromine
atom in the crystals seems to be much different from each other.
However, it is still difficult to estimate the precise steric
bulkiness of the Rind groups on the basis of the X-ray
molecular structures, because dynamic steric factors must be
taken into account in any reactions of the Rind-substituted
species in solution. In this regard, we have obtained clear-cut
results to demonstrate that the steric bulkiness of MPhind μ
MsFluind is much greater than EMind μ Eind in organo-
copper(I) chemistry.52 Thus, while the EMind and Eind groups
on copper lead to the selective formation of dimers of
organobromocuprate and diorganocuprate, the MPhind and
MsFluind groups exclusively afforded the corresponding
monomers.
Conclusion
We have developed a series of fused-ring octa-R-substituted
s-hydrindacenyl bromides. All the Rind-Br can be transformed
into the reactive bulky aryllithium “Rind-Li” as the key

1184 Bull. Chem. Soc. Jpn. Vol. 84, No. 11 (2011) BCSJ AWARD ARTICLE
Figure 3. Molecular structures of (a) Eind-Br, (b) HEind-Br, (c) MPind-Br, (d) MsHind-Br, (e) MPhind-Br, and (f) MsFluind-Br: top
views (left), front views (center), and space filling models (right).
reagents for introduction into a variety of main group elements
and transition metals. Thus, a series of Rind groups have
Experimental
already been found to act as unique protecting groups not only
in the main group chemistry of groups 13-17, but also in
organo-transition metal chemistry.50-59 Further structural elab-
oration would be envisaged for future and wider applications,
as represented by the introduction of chirality and functional
groups as the side groups and/or on the vacant para-position.
Such studies are now under investigation.
General Procedure.
All experiments of the air- and
moisture-sensitive compounds were performed under an inert
atmosphere of argon or nitrogen. Anhydrous THF, Et2O,
dichloromethane, hexane, and toluene were dried by passage
through columns of activated alumina and a supported copper
catalyst supplied by Hansen & Co., Ltd. All other chemicals and
gases were used as received. Dibenzofulvene74 and dimethyl

T. Matsuo et al.
Bull. Chem. Soc. Jpn. Vol. 84, No. 11 (2011) 1185
5-bromoisophthalate71 were prepared by the modified literature
procedures. Thin layer chromatography (TLC) was performed
on plates coated with 0.25 nm thick Silica Gel 60 F-254 (Merck
Ltd.). Column chromatography was performed using neutral
Silica Gel 60 N (Kanto Chemical Co., Ltd.), Kieselgel 60 (70-
230 mesh) (Merck), or neutral silica gel PSQ 100B (Fuji Silysia
Chemical). Gas chromatography mainly for the monitoring
of the bromination reaction of Rind-H was performed by a
SHIMADZU GC-8A with SHIMADZU column packing
(Silicone SE-30 5% or OV-17%). The nuclear magnetic
resonance (NMR) measurements were carried out by a JEOL
if pure) in CH2Cl2 (500 mL) was added CaCl2 powder (ca.
100 g), and then HCl gas was introduced into the mixture for
2 h at 0 °C. After the reaction was completed (checked by
1H NMR spectra), N2 gas was bubbled for 1 h to remove the
remaining HCl gas, and the reaction mixture was filtered
through a plug of Celiteμ. The filtrate was concentrated on a
rotary evaporator to reduce the volume to ca. 200 mL. The
CH2Cl2 solution of the crude product was used for the next
1
reaction without further purification. H NMR (CDCl3): ¤ 0.86
(t, J = 7.5 Hz, 12H, CH3), 2.16 (q, J = 7.5 Hz, 8H, CH2), 7.27-
7.38 (m, 3H, ArH), 7.54-7.55 (m, 1H, ArH). 13C NMR
(CDCl3): ¤ 9.4, 37.7, 81.0, 125.2, 125.4, 127.8, 142.6.
1
ECS-400 spectrometer (399.8 MHz for H and 100.5 MHz for
1
13C) or JEOL EX-270 spectrometer (270.0 MHz for H and
(3) Eind-H (1,1,3,3,5,5,7,7-Octaethyl-s-hydrindacene):
To the CH2Cl2 solution of 1,3-bis(1-chloro-1-ethylpropyl)ben-
zene (ca. 200 mL, 0.33 mol if pure) and 2-ethyl-1-butene
(55.5 g, 0.66 mol) was dropwise added BCl3 (1.0 M solution in
CH2Cl2, 115 mL, 115 mmol) at 0 °C over a 1 h period. After
stirring overnight at room temperature, the reaction mixture
was quenched with 1 M NaOH aq. (500 mL) at 0 °C. After the
organic layer was separated, the aqueous layer was extracted
with CH2Cl2 (200 mL). The combined organic layer was
washed with water and brine, and dried over Na2SO4. After
evaporation of the solvent, the residual solid was dissolved in
hexane and filtered through a short silica gel column. The
solvent was removed from the filtrate under reduced pressure to
give the crude Eind-H as a colorless solid (94.2 g, 0.25 mol,
75% yield if pure). The crude product was used for the next
67.9 MHz for 13C). Chemical shifts (¤) are listed by definition
as dimensionless numbers and relative to 1H (residual) or
13C NMR chemical shifts of the solvent (residual C6D5H in
C6D6, 1H(¤) = 7.15 and 13C(¤) = 128.0; residual CHCl3 in
1
CDCl3, H(¤) = 7.24 and 13C(¤) = 77.0). The absolute values
of the coupling constants are given in Hertz (Hz), regardless of
their signs. Multiplicities are abbreviated as singlet (s), doublet
(d), triplet (t), quartet (q), multiplet (m), and broad (br). The
elemental analyses (C and H) and mass spectroscopy were
performed at the Advanced Technology Support Division of
RIKEN Advanced Science Institute or Micro Analysis Division
and Mass Spectrum Division of Institute for Chemical Re-
search, Kyoto University. Melting points (mp) were determined
by a Yazawa BY-2 instrument or a Stanford Research Systems
MPA100 OptiMelt instrument.
1
reaction without further purification. H NMR (CDCl3): ¤ 0.79
The solubility measurement experimental procedure is as
follows. A suspension of REind-Br in hexane was ultrasoni-
cally treated for 3 min. After the suspension was stored for
10 min, a portion of the upper clear saturated solution (100 ¯L)
was transferred to a weighed flask. The solvent was evaporated
and the remaining solid REind-Br was dried under vacuum for
2 h and weighed again.
Preparation of Eind-Br (4-Bromo-1,1,3,3,5,5,7,7-octaeth-
yl-s-hydrindacene). A large-scale synthesis of Eind-Br was
carried out on the basis of the previously reported procedures50
with some modifications.
(1) 1,3-Bis(1-ethyl-1-hydroxypropyl)benzene: To a solu-
tion of ethylmagnesium bromide (1.65 mol) in THF (600 mL)
was dropwise added a solution of dimethyl isophthalate (64.0 g,
0.33 mol) in THF (150 mL) at 0 °C over a 2-h period. After
stirring overnight at room temperature, the reaction mixture
was quenched with 3 M HCl aq. (600 mL) at 0 °C. After the
organic layer was separated, the aqueous layer was extracted
with Et2O (200 mL). The combined organic layer was
successively washed with water, NaHCO3 aq., and brine and
dried over Na2SO4. After evaporation of the solvent, i-PrOH
(100 mL) was added to the residue. The volatiles were then
removed under reduced pressure to give the crude 1,3-bis(1-
ethyl-1-hydroxypropyl)benzene as a light yellow solid (81.5 g,
0.33 mol, 99% yield if pure). The crude product was used
for the next reaction without further purification. 1H NMR
(CDCl3): ¤ 0.73 (t, J = 7.5 Hz, 12H, CH3), 1.76-1.91 (m, 8H,
CH2), 7.20-7.35 (m, 4H, ArH); 13C NMR (CDCl3): ¤ 8.1, 35.3,
77.7, 122.7, 123.5, 127.8, 145.3.
(t, J = 7.5 Hz, 24H, CH3), 1.48-1.69 (m, 16H, CH2), 1.77
(s, 4H, CH2), 6.63 (s, 2H, ArH); 13C NMR (CDCl3): ¤ 9.3, 33.2,
45.4, 48.9, 118.8, 147.6.
(4) Eind-Br: To a solution of Eind-H (94.2 g, 0.25 mol if
pure) in triethyl phosphate (600 mL) was added bromine
(100 mL, 312 g, 1.95 mol). The reaction mixture, protected
from light and moisture, was stirred overnight at 70 °C. After
completion of the reaction (checked by GC analysis), the
residual bromine was quenched with Na2SO3 aq. The resulting
yellow suspension was filtered and washed with water to give
the crude product as a light yellow solid. This solid was
dissolved in hexane and filtered through a short silica gel
column. After the solvent was removed from the filtrate, the
residue was recrystallized from hexane (200 mL) and i-PrOH
(100 mL) to give Eind-Br as colorless crystals (59.2 g,
0.13 mol, 39% yield for 4 steps): mp 157.3-158.2 °C. 1H NMR
(CDCl3): ¤ 0.77 (t, J = 7.3 Hz, 12H, CH3), 0.81 (t, J = 7.3 Hz,
12H, CH3), 1.49-1.57 (m, 4H, CH2), 1.58-1.66 (m, 4H, CH2),
1.77-1.86 (m, 4H, CH2), 1.83 (s, 4H, CH2), 1.92-2.01 (m, 4H,
CH2), 6.59 (s, 1H, ArH); 13C NMR (CDCl3): ¤ 9.1, 9.3, 31.1,
32.9, 43.1, 47.9, 53.2, 118.2, 118.6, 144.9, 151.9. Anal. Calcd
for C28H45Br: C, 72.86; H, 9.83%. Found: C, 72.82; H, 9.80%.
The 1H and 13C NMR spectra of Eind-Br are shown in
Figure 4.
Preparation of Br-Eind-Br (4,8-Dibromo-1,1,3,3,5,5,7,7-
octaethyl-s-hydrindacene). To a solution of Eind-H (20.2 g,
52.8 mmol) in triethyl phosphate (380 mL) was added bromine
(150 mL, 468 g, 2.93 mol). The reaction mixture, protected
from light and moisture, was stirred for 4 days at 70 °C. After
completion of the reaction (checked by GC analysis), the
residual bromine was quenched with Na2SO3 aq. The resulting
(2) 1,3-Bis(1-chloro-1-ethylpropyl)benzene: To a solution
of 1,3-bis(1-ethyl-1-hydroxypropyl)benzene (81.5 g, 0.33 mol

1186 Bull. Chem. Soc. Jpn. Vol. 84, No. 11 (2011) BCSJ AWARD ARTICLE
was warmed to 0 °C, then stirred overnight. After a similar
work-up procedure to Eind-H, the crude Mind-H was filtered
through a short silica gel column. The solvent was removed
from the filtrate under reduced pressure to give Mind-H as a
colorless solid (26.7 g, 98.7 mmol, 48% yield for 2 steps): mp
85 °C (sublimation), 210 °C (Ref. 66). 1H NMR (CDCl3):
¤ 1.29 (s, 24H, CH3), 1.89 (s, 4H, CH2), 6.80 (s, 2H, ArH);
13C NMR (CDCl3): ¤ 31.7, 42.1, 57.2, 115.9, 149.9. Anal.
Calcd for C20H30: C, 88.82; H, 11.18%. Found: C, 88.79; H,
11.23%.
(3) Mind-Br (4-Bromo-1,1,3,3,5,5,7,7-octamethyl-s-hy-
drindacene):
To a heated solution of Mind-H (7.00 g,
25.9 mmol) in triethyl phosphate (120 mL) and hexane
(120 mL) at 60 °C was added bromine (13.3 mL, 259 mmol).
The reaction mixture, protected from light and moisture, was
stirred for 10 h at 60 °C. After completion of the reaction
(checked by GC analysis), the residual bromine was quenched
with Na2SO3 aq. The resulting light yellow solid was collected
by filtration and washed with ethanol to give Mind-Br as a
colorless solid (first crop, 5.02 g. 14.3 mmol, 55% yield). To the
filtrate was added toluene, the organic layer was separated,
washed with H2O and brine, dried over MgSO4, and filtered.
After evaporation of the solvent from the filtrate, the residual
solid was washed with ethanol to give Mind-Br as a colorless
solid (second crop, 2.15 g. 6.15 mmol, 23% yield): mp 130 °C
(sublimation), 225-225.5 °C (Ref. 70). 1H NMR (CDCl3):
¤ 1.27 (s, 12H, CH3), 1.51 (s, 12H, CH3), 1.93 (s, 4H, CH2),
6.77 (s, 1H, ArH); 13C NMR (CDCl3): ¤ 29.2, 31.6, 41.2, 45.6,
59.0, 115.8, 146.4, 150.1, 153.7. HRMS (EI) Calcd for
C20H2979Br: 348.1453. Found: 348.1461. Anal. Calcd for
C20H29Br: C, 68.76; H, 8.37%. Found: C, 68.71; H, 8.42%.
Preparation of Br-Mind-Br (4,8-Dibromo-1,1,3,3,5,5,7,7-
octamethyl-s-hydrindacene).
To a solution of Mind-H
Figure 4. (a) 1H and (b) 13C NMR spectra of Eind-Br
(CDCl3, 298 K).
(2.70 g, 10.0 mmol) in triethyl phosphate (80 mL) and hexane
(80 mL) at 60 °C was added bromine (31 mL, 96.1 g, 0.60 mol).
The reaction mixture, protected from light and moisture, was
stirred for 8 h at 70 °C. After completion of the reaction
(checked by 1H NMR), the residual bromine was quenched
with Na2SO3 aq. The resulting yellow suspension was filtered
and the residue was washed with water and ethanol to give
Br-Mind-Br as off-white crystals (3.66 g, 8.53 mmol, 85%
yield): mp 178 °C (sublimation). 1H NMR (CDCl3): ¤ 1.50
(s, 24H, CH3), 1.96 (s, 4H, CH2); 13C NMR (CDCl3): ¤ 29.1,
44.6, 61.2, 117.4, 150.1. Anal. Calcd for C20H28Br2: C, 56.09;
H, 6.59%. Found: C, 56.03; H, 6.51%.
yellow suspension was filtered and the residue was washed
with water and ethanol, and dried to give Br-Eind-Br as
colorless crystals (15.5 g, 28.7 mmol, 54% yield): mp 209-
1
211 °C. H NMR (CDCl3): ¤ 0.82 (t, J = 7.3 Hz, 24H, CH3),
1.80-1.95 (m, 16H, CH2), 1.89 (s, 4H, CH2); 13C NMR
(CDCl3): ¤ 9.2, 30.7, 40.5, 52.2, 118.9, 149.2. Anal. Calcd
for C28H44Br2: C, 62.23; H, 8.21%. Found: C, 62.24; H, 8.23%.
Preparation of Mind-Br (4-Bromo-1,1,3,3,5,5,7,7-octa-
methyl-s-hydrindacene).62 (1) 1,3-Bis(1-chloro-1-methyl-
ethyl)benzene:
1,3-Bis(1-hydroxy-1-methylethyl)benzene
Preparation of EMind-Br (4-Bromo-1,1,7,7-tetra-
ethyl-3,3,5,5-tetramethyl-s-hydrindacene.75 (1) MEind-H
(1,1,7,7-Tetraethyl-3,3,5,5-tetramethyl-s-hydrindacene):
This compound was prepared similar to Eind-H starting from
1,3-bis(1-chloro-1-methylethyl)benzene (37.5 g, 0.16 mol), 2-
ethyl-1-butene (31.0 g, 0.37 mol), and BCl3 (1.0 M solution in
CH2Cl2, 10 mL, 10 mmol) in CH2Cl2 (200 mL), and was
isolated as a colorless solid by Kugelrohr distillation (135-
150 °C/0.1 mmHg) (25.6 g, 78.4 mmol, 48% yield): mp 63-
(40.0 g, 206 mmol) was treated with HCl gas in the presence
of CaCl2 powder (ca. 40 g) in CH2Cl2 (400 mL) to give 1,3-
bis(1-chloro-1-methylethyl)benzene as a light yellow oil
(44.2 g, 190 mmol, 93% yield), which was used for the next
1
reaction without further purification. H NMR (CDCl3): ¤ 2.01
(s, 12H, CH3), 7.33 (t, J = 7.8 Hz, 1H, ArH), 7.49 (dd, J =
1.8 Hz, J = 7.8 Hz, 2H, ArH), 7.83 (t, J = 7.8 Hz, 1H, ArH).
(2) Mind-H (1,1,3,3,5,5,7,7-Octamethyl-s-hydrindacene):
1
To
a
solution of 1,3-bis(1-chloro-1-methylethyl)benzene
65 °C. H NMR (CDCl3): ¤ 0.76 (t, J = 7.4 Hz, 12H, CH3),
(44.5 g, 190 mmol if pure) in CH2Cl2 (300 mL) was introduced
isobutene gas (ca. 40 g, ca. 0.71 mol) at ¹80 °C over a 2-h
period. To the mixture was then added BCl3 (1.0 M solution in
CH2Cl2, 40 mL, 40 mmol) at ¹80 °C. The resulting mixture
1.26 (s, 12H, CH3), 1.56-1.61 (m, 8H, CH2), 1.83 (s, 4H, CH2),
6.59 (s, 1H, ArH), 6.75 (s, 1H, ArH); 13C NMR (CDCl3): ¤ 9.2,
32.2, 33.1, 41.7, 49.5, 51.3, 115.9, 118.5, 146.4, 151.0. HRMS
(EI) Calcd for C24H38: 326.2974. Found: 326.2958.

T. Matsuo et al.
(2) EMind-Br:
Bull. Chem. Soc. Jpn. Vol. 84, No. 11 (2011) 1187
A reaction of MEind-H (14.3 g, 43.8
(2) xMEind-H (1,1,5,5-Tetraethyl-3,3,7,7-tetramethyl-s-
mmol) with bromine (15 mL, 0.29 mol) in triethyl phosphate
(150 mL) at room temperature overnight gave EMind-Br. After
the reaction mixture was quenched with Na2SO3 aq., the
resulting yellow suspension was filtered and washed with
water and EtOH, and dried in vacuo to afford EMind-Br as
colorless crystals (17.2 g, 42.4 mmol, 97% yield): mp 112-
hydrindacene):
This compound was prepared similar to
Eind-H starting from 1,4-bis(1-chloro-1-methylethyl)benzene
(22.8 g, 98.7 mmol if pure), 2-ethyl-1-butene (17.2 g, 205
mmol), and BCl3 (1.0 M solution in CH2Cl2, 16 mL, 16 mmol)
in CH2Cl2 (160 mL), and was isolated as colorless crystals
(28.4 g, 86.9 mmol, 87% yield for 2 steps): mp 65-67 °C.
1H NMR (CDCl3): ¤ 0.78 (t, J = 7.3 Hz, 12H, CH3), 1.26
(s, 12H, CH3), 1.49-1.69 (m, 8H, CH2), 1.84 (s, 4H, CH2), 6.69
(s, 2H, ArH); 13C NMR (CDCl3): ¤ 9.2, 32.1, 32.9, 41.9, 49.5,
51.5, 117.2, 147.1, 150.4. HRMS (EI) Calcd for C24H38:
326.2974. Found: 326.2982.
1
113 °C. H NMR (CDCl3): ¤ 0.74 (t, J = 7.6 Hz, 12H, CH3),
1.49 (s, 12H, CH3), 1.53-1.58 (m, 8H, CH2), 1.86 (s, 4H,
CH2), 6.54 (s, 1H, ArH); 13C NMR (CDCl3): ¤ 9.0, 29.4, 33.1,
45.3, 48.6, 52.8, 116.9, 118.4, 147.4, 150.2. HRMS (EI)
Calcd for C24H3779Br: 404.2079. Found: 404.2068. Anal.
Calcd for C24H37Br: C, 71.09; H, 9.20%. Found: C, 71.47; H,
9.11%.
(3) xMEind-Br:
The reaction of xMEind-H (5.00 g,
15.3 mmol) with bromine (6.3 mL, 123 mmol) in triethyl
phosphate (130 mL) at 60 °C for 7 h gave xMEind-Br as
colorless crystals (5.20 g, 12.8 mmol, 84% yield): mp 96-
97 °C. 1H NMR (CDCl3): ¤ 0.73 (t, J = 8.0 Hz, 6H, CH3), 0.75
(t, J = 8.0 Hz, 6H, CH3), 1.23 (s, 6H, CH3), 1.48 (s, 6H, CH3),
1.48-1.62 (m, 4H, CH2), 1.60-1.71 (m, 2H, CH2), 1.87 (s, 4H,
CH2), 2.00-2.07 (m, 2H, CH2), 6.61 (s, 1H, ArH); 13C NMR
(CDCl3): ¤ 9.1, 9.5, 29.4, 31.3, 32.0, 33.1, 40.8, 45.2, 48.6,
49.7, 53.1, 54.1, 117.1, 117.2, 143.6, 147.1, 150.9, 154.5.
HRMS (EI) Calcd for C24H3779Br: 404.2079. Found: 404.2068.
Anal. Calcd for C24H37Br: C, 71.09; H, 9.20%. Found: C,
70.69; H, 9.30%.
Preparation of MEind-Br (4-Bromo-3,3,5,5-tetraethyl-
1,1,7,7-tetramethyl-s-hydrindacene).75
(1) 1-Bromo-3,5-
bis(1-hydroxy-1-methylethyl)benzene: This compound was
prepared similar to 1,3-bis(1-ethyl-1-hydroxypropyl)benzene
starting from dimethyl 5-bromoisophthalate71 (7.00 g, 25.6
mmol) and methylmagnesium bromide (3.0 M solution in Et2O,
45 mL, 135 mmol) in THF (150 mL). The resulting light yellow
solid was washed with hexane and CH2Cl2 to give the crude
1-bromo-3,5-bis(1-hydroxy-1-methylethyl)benzene as a color-
less solid (5.54 g, 20.3 mmol, 79% if pure), which was used
for the next reaction without further purification. 1H NMR
(CDCl3): ¤ 1.55 (s, 12H, CH3), 7.48 (d, J = 1.6 Hz, 2H, ArH),
7.53 (t, J = 1.6 Hz, 1H, ArH); 13C NMR (CDCl3): ¤ 31.7, 72.4,
119.2, 122.3, 126.1, 151.3.
Preparation of PEind-Br (4-Bromo-3,3,5,5-tetraethyl-
1,1,7,7-tetrapropyl-s-hydrindacene).75
droxy-1-propylbutyl)benzene:
(1) 1,3-Bis(1-hy-
The reaction of dimethyl
(2)
1-Bromo-3,5-bis(1-chloro-1-methylethyl)benzene:
isophthalate (7.77 g, 40.0 mmol) with propylmagnesium chlo-
ride (2.0 M solution in Et2O, 100 mL, 200 mmol) in THF
(100 mL) gave 1,3-bis(1-hydroxy-1-propylbutyl)benzene as a
light yellow oil (11.3 g, 36.9 mmol, 92% if pure), which was
used for the next reaction without further purification. 1H NMR
(CDCl3): ¤ 0.81 (t, J = 7.2 Hz, 12H, CH3), 0.96-1.10 (m, 4H,
CH2), 1.18-1.34 (m, 4H, CH2), 1.68-1.84 (m, 8H, CH2), 1.78
(s, 2H, OH), 7.16-7.22 (m, 2H, ArH), 7.22-7.28 (m, 1H, ArH),
7.32-7.36 (m, 1H, ArH); 13C NMR (CDCl3): ¤ 14.4, 16.7, 45.3,
77.2, 122.1, 123.1, 127.6, 146.1.
The crude 1-bromo-3,5-bis(1-hydroxy-1-methylethyl)benzene
(4.09 g, 15.0 mmol if pure) was treated with HCl gas in the
presence of CaCl2 powder (ca. 10 g) in CH2Cl2 (150 mL) to
give 1-bromo-3,5-bis(1-chloro-1-methylethyl)benzene as a col-
orless solid (4.63 g, 15.0 mmol, 100% yield if pure), which was
used for the next reaction without further purification. 1H NMR
(CDCl3): ¤ 1.96 (s, 12H, CH3), 7.60 (d, J = 1.8 Hz, 2H, ArH),
7.72 (t, J = 1.8 Hz, 1H, ArH); 13C NMR (CDCl3): ¤ 34.2, 68.5,
121.7, 122.1, 127.9, 148.3.
(3) MEind-Br:
This compound was prepared from
(2) 1,3-Bis(1-chloro-1-propylbutyl)benzene: The crude
1,3-bis(1-hydroxy-1-propylbutyl)benzene (11.3 g, 36.9 mmol if
pure) was treated with HCl gas in the presence of CaCl2
powder (ca. 15 g) in CH2Cl2 (100 mL) to give 1,3-bis(1-chloro-
1-propylbutyl)benzene as a brown oil (12.7 g, 36.9 mol, 100%
yield if pure), which was used for the next reaction without
1-bromo-3,5-bis(1-chloro-1-methylethyl)benzene (4.63 g, 15.0
mmol if pure), 2-ethyl-1-butene (2.70 g, 32.1 mmol), BCl3
(1.0 M solution in CH2Cl2, 15 mL, 15 mmol), and CH2Cl2
(80 mL), and was isolated as colorless crystals by recrystalli-
zation from CH2Cl2/MeOH (3.65 g, 9.00 mmol, 60% yield for
3 steps): mp 86-89 °C. 1H NMR (CDCl3): ¤ 0.72 (t, J = 7.6 Hz,
12H, CH3), 1.24 (s, 12H, CH3), 1.58-1.68 (m, 4H, CH2), 1.87
(s, 4H, CH2), 2.03-2.13 (m, 4H, CH2), 6.67 (s, 1H, ArH);
13C NMR (CDCl3): ¤ 9.5, 31.4, 32.1, 40.8, 50.0, 54.1, 115.8,
117.6, 143.1, 155.2. HRMS (EI) Calcd for C24H3779Br:
404.2079. Found: 404.2074. Anal. Calcd for C24H37Br: C,
71.09; H, 9.20%. Found: C, 70.64; H, 9.17%.
Preparation of xMEind-H (1,1,5,5-Tetraethyl-3,3,7,7-tet-
ramethyl-s-hydrindacene).75 (1) 1,4-Bis(1-chloro-1-meth-
ylethyl)benzene:66 1,4-Bis(1-hydroxy-1-methylethyl)benzene
(19.4 g, 100 mmol) was treated with HCl gas in the presence of
CaCl2 powder (ca. 35 g) in CH2Cl2 (300 mL) to give 1,3-bis(1-
chloro-1-methylethyl)benzene as a yellow solid (22.8 g, 98.7
mmol, 99% yield), which was used for the next reaction
without further purification.
1
further purification. H NMR (CDCl3): ¤ 0.85 (t, J = 7.2 Hz,
12H, CH3), 1.12-1.24 (m, 4H, CH2), 1.30-1.50 (m, 4H, CH2),
2.04-2.12 (m, 8H, CH2), 7.20-7.40 (m, 4H, ArH); 13C NMR
(CDCl3): ¤ 14.0, 17.9, 47.2, 79.4, 124.7, 125.1, 127.7, 143.3.
(3) EPind-H (1,1,7,7-Tetraethyl-3,3,5,5-tetrapropyl-s-hy-
drindacene): This compound was prepared similar to Eind-H
starting from 1,3-bis(1-chloro-1-propylbutyl)benzene (12.7 g,
36.9 mmol if pure), 2-ethyl-1-butene (7.00 g, 82.6 mmol), and
BCl3 (1.0 M solution in CH2Cl2, 40 mL, 40 mmol) in CH2Cl2
(80 mL), and was isolated as colorless crystals (4.21 g,
1
9.58 mmol, 26% yield for 3 steps): mp 125-128 °C. H NMR
(CDCl3): ¤ 0.79 (t, J = 7.3 Hz, 12H, CH3), 0.85 (t, J = 7.3 Hz,
12H, CH3), 1.08-1.21 (m, 4H, CH2), 1.22-1.35 (m, 4H, CH2),
1.41-1.67 (m, 16H, CH2), 1.78 (s, 4H, CH2), 6.61 (s, 1H, ArH),
6.64 (s, 1H, ArH); 13C NMR (CDCl3): ¤ 9.2, 15.0, 18.1, 33.1,

1188 Bull. Chem. Soc. Jpn. Vol. 84, No. 11 (2011) BCSJ AWARD ARTICLE
44.1, 46.4, 48.6, 49.0, 118.6, 118.9, 147.4, 148.4. HRMS (EI)
Calcd for C32H54: 438.4226. Found: 438.4234.
(m, 8H, CH2), 1.76-2.00 (m, 12H, CH2), 6.61 (s, 1H, ArH);
13C NMR (CDCl3): ¤ 9.9, 14.6, 24.1, 27.7, 31.7, 41.7, 44.5,
48.1, 53.9, 100.9, 118.9, 145.3, 153.0. HRMS (EI) Cacld for
C36H6179Br: 572.3957. Found: 572.3979. Anal. Calcd for
C36H61Br: C, 75.36; H, 10.72%. Found: C, 75.27; H, 10.89%.
Preparation of P5Eind-Br (4-Bromo-3,3,5,5-tetraethyl-
1,1,7,7-tetrapentyl-s-hydrindacene). (1) 1,3-Bis(1-hydroxy-
1-pentylhexyl)benzene: The reaction of dimethyl isophtha-
late (50.0 g, 258 mmol) with pentylmagnesium bromide (1.29
mol in Et2O (800 mL)) in Et2O (400 mL) gave 1,3-bis(1-
hydroxy-1-pentylhexyl)benzene as a light yellow gum (108 g,
258 mmol, 100% if pure), which was used for the next reaction
(4) PEind-Br:
The reaction of EPind-H (4.13 g, 9.42
mmol) and bromine (5.0 mL, 100 mmol) in triethyl phosphate
(80 mL) at 60 °C overnight gave a mixture of regioisomers,
PEind-Br and EPind-Br, in ca. 4:1 ratio as estimated by
1H NMR spectrum. The major product, PEind-Br, was isolated
as colorless crystals by repeated recrystallization from hexane
(2.04 g, 3.94 mmol, 42% yield): mp 130-131 °C. 1H NMR
(CDCl3): ¤ 0.77 (t, J = 7.3 Hz, 12H, CH3), 0.86 (t, J =
7.3 Hz, 12H, CH3), 1.11-1.37 (m, 8H, CH2), 1.40-1.48 (m, 4H,
CH2), 1.53-1.61 (m, 4H, CH2), 1.76-1.85 (m, 4H, CH2), 1.84
(s, 4H, CH2), 1.91-2.00 (m, 4H, CH2), 6.61 (s, 1H, ArH);
13C NMR (CDCl3): ¤ 9.4, 14.9, 18.0, 31.0, 43.8, 44.1, 47.7,
53.4, 118.1, 118.4, 144.6, 152.5. HRMS (EI) Calcd
for C32H5379Br: 516.3331. Found: 516.3325. Anal. Calcd for
C32H53Br: C, 74.25; H, 10.32%. Found: C, 74.07; H, 10.44%.
Preparation of BEind-Br (4-Bromo-1,1,7,7-tetrabutyl-
3,3,5,5-tetaethyl-s-hydrindacene). (1) 1,3-Bis(1-butyl-1-hy-
droxypentyl)benzene: The reaction of dimethyl isophthalate
(15.0 g, 77.2 mmol) with butylmagnesium bromide (503 mmol
in Et2O) in Et2O (250 mL) gave 1,3-bis(1-butyl-1-hydroxy-
pentyl)benzene as a light yellow oil (27.3 g, 75.3 mmol, 98% if
pure), which was used for the next reaction without further
purification.
1
without further purification. H NMR (CDCl3): ¤ 0.81 (t, J =
6.8 Hz, 12H, CH3), 0.96-1.05 (m, 4H, CH2), 1.14-1.31 (m,
20H, CH2), 1.68 (s, 2H, OH), 1.71-1.86 (m, 8H, CH2), 7.21-
7.29 (m, 3H, ArH), 7.31-7.33 (m, 1H, ArH).
(2) 1,3-Bis(1-chloro-1-pentylhexyl)benzene: The crude
1,3-bis(1-hydroxy-1-pentylhexyl)benzene (108 g, 258 mmol if
pure) was treated with HCl gas in the presence of CaCl2 powder
(ca. 170 g) in CH2Cl2 (1.2 L) to give 1,3-bis(1-chloro-1-pen-
tylhexyl)benzene as a brown oil (106 g, 0.23 mol, 90% yield if
pure), which was used for the next reaction without further
purification. 1H NMR (CDCl3): ¤ 0.83 (t, J = 6.4 Hz, 12H,
CH3), 1.10-1.29 (m, 24H, CH2), 2.06-2.19 (m, 8H, CH2), 7.25-
7.33 (m, 1H, ArH), 7.36-7.40 (m, 2H, ArH), 7.51 (s, 1H, ArH).
(3) EP5ind-H (1,1,7,7-Tetraethyl-3,3,5,5-tetrapentyl-s-hy-
drindacene): This compound was prepared similar to Eind-H
starting from 1,3-bis(1-chloro-1-pentylhexyl)benzene (106 g,
232 mmol if pure), 2-ethyl-1-butene (44.8 g, 533 mmol), and
BCl3 (1.0 M solution in CH2Cl2, 116 mL, 116 mmol) in CH2Cl2
(600 mL), and was isolated as a light yellow oil (100 g,
181 mmol, 78% yield if pure). The crude product was used for
the next reaction without further purification. 1H NMR (CDCl3):
¤ 0.80 (t, J = 7.3 Hz, 12H, CH3), 0.85 (t, J = 6.9 Hz, 12H,
CH3), 1.14-1.32 (m, 24H, CH2), 1.44-1.68 (m, 16H, CH2), 1.79
(s, 4H, CH2), 6.62 (s, 1H, ArH), 6.65 (s, 1H, ArH).
(2) 1,3-Bis(1-butyl-1-chloropentyl)benzene:
The crude
1,3-bis(1-butyl-1-hydroxypentyl)benzene (14.8 g, 40.8 mmol if
pure) was treated with HCl gas in the presence of CaCl2
powder (7.0 g) in CH2Cl2 (100 mL) to give 1,3-bis(1-butyl-1-
chloropentyl)benzene as a light yellow oil (16.3 g, 40.8 mmol,
100% yield if pure), which was used for the next reaction
1
without further purification. H NMR (CDCl3): ¤ 0.84 (t, J =
7.5 Hz, 12H, CH3), 1.04-1.42 (m, 16H, CH2), 1.96-2.08 (m,
8H, CH2), 7.26-7.38 (m, 3H, ArH), 7.50-7.53 (m, 1H, ArH);
13C NMR (CDCl3): ¤ 14.2, 23.0, 27.1, 45.0, 79.8, 124.7, 125.3,
128.4, 143.2.
(3) EBind-H (1,1,7,7-Tetrabutyl-3,3,5,5-tetraethyl-s-hy-
drindacene): This compound was prepared similar to Eind-
H starting from 1,3-bis(1-butyl-1-chloropentyl)benzene (16.3 g,
40.8 mmol if pure), 2-ethyl-1-butene (6.89 g, 81.9 mmol), and
BCl3 (1.0 M solution in CH2Cl2, 41 mL, 41 mmol) in CH2Cl2
(60 mL), and was isolated as colorless crystals by column
chromatography (silica gel, hexane as eluent, Rf = 0.75) and
recrystallization from hexane (3.85 g, 7.78 mmol, 19% yield for
3 steps): mp 66.5-67.3 °C. 1H NMR (CDCl3): ¤ 0.80, 0.86
(t © 2, J = 7.5 Hz, 24H, overlapped, CH3), 1.08-1.31 (m, 16H,
CH2), 1.43-1.70 (m, 16H, CH2), 1.79 (s, 4H, CH2), 6.62 (s, 1H,
ArH), 6.65 (s, 1H, ArH); 13C NMR (CDCl3): ¤ 9.5, 14.4, 23.8,
27.3, 33.2, 41.4, 46.7, 48.5, 49.1, 118.86, 118.94, 147.5, 148.3.
HRMS (EI) Cacld for C36H62: 494.4852. Found: 494.4857.
(4) P5Eind-Br: The reaction of P5Eind-H (100 g, 0.18 mol
if pure) with bromine (186 mL, 3.63 mol) in triethyl phosphate
(500 mL) at 35 °C for 2 days gave a mixture of regioisomers,
P5Eind-Br and EP5ind-Br, in ca. 4:1 ratio as estimated by
1H NMR spectrum. The major product, P5Eind-Br, was isolated
as colorless crystals by recrystallization from hexane/EtOH
(33.5 g, 53.2 mmol, 21% yield for 4 steps): mp 88 °C. 1H NMR
(CDCl3): ¤ 0.77 (t, J = 7.3 Hz, 12H, CH3), 0.86 (t, J = 6.9 Hz,
12H, CH3), 1.13-1.32 (m, 24H, CH2), 1.43-1.50 (m, 4H, CH2),
1.54-1.61 (m, 4H, CH2), 1.77-1.87 (m, 8H, CH2), 1.92-2.01
(m, 4H, CH2), 6.61 (s, 1H, ArH); 13C NMR (CDCl3): ¤ 9.5,
14.2, 22.8, 24.6, 31.2, 32.9, 41.4, 44.3, 47.7, 53.5, 118.2, 118.6,
144.8, 152.6. HRMS (EI) Calcd for C40H6979Br: 628.4583.
Found: 628.4560. Anal. Calcd for C40H69Br: C, 76.27; H,
11.04%. Found: C, 76.25; H, 11.12%.
(4) BEind-Br:
The reaction of EBind-H (3.50 g,
7.07 mmol) with bromine (3.8 mL, 73.8 mmol) in triethyl
phosphate (50 mL) at 70 °C overnight gave a mixture of
regioisomers, BEind-Br and EBind-Br, in ca. 4:1 ratio as
Preparation of HEind-Br (4-Bromo-3,3,5,5-tetraethyl-
1,1,7,7-tetrahexyl-s-hydrindacene). (1) 1,3-Bis(1-hydroxy-
1-hexylheptyl)benzene: The reaction of dimethyl isophtha-
late (30.0 g, 155 mmol) with hexylmagnesium bromide
(0.77 mol in Et2O (500 mL)) in Et2O (400 mL) to give 1,3-
bis(1-hydroxy-1-hexylheptyl)benzene as a yellow gum (34.8 g,
73.3 mmol, 48% if pure), which was used for the next reaction
1
estimated by H NMR spectrum. The major product BEind-Br
was isolated as colorless crystals by recrystallization from
hexane (2.29 g, 3.99 mmol, 56% yield): mp 91.7-92.2 °C.
1H NMR (CDCl3): ¤ 0.77 (t, J = 7.5 Hz, 12H, CH3), 0.87 (t,
J = 7.5 Hz, 12H, CH3), 1.12-1.27 (m, 16H, CH2), 1.41-1.61
1
without further purification. H NMR (CDCl3): ¤ 0.83 (t, J =

T. Matsuo et al.
Bull. Chem. Soc. Jpn. Vol. 84, No. 11 (2011) 1189
6.9 Hz, 12H, CH3), 0.96-1.05 (m, 4H, CH2), 1.14-1.31 (m,
28H, CH2), 1.69 (s, 2H, OH), 1.72-1.86 (m, 8H, CH2), 7.21-
7.29 (m, 3H, ArH), 7.31-7.33 (m, 1H, ArH).
zene (21.5 g, 69.3 mmol), 2-propyl-1-pentene (17.1 g, 153
mmol), and BCl3 (1.0 M solution in CH2Cl2, 10 mL, 10 mmol)
in CH2Cl2 (80 mL), and was isolated as colorless crystals
by recrystallization from acetone (11.6 g, 25.1 mmol, 36%
(2) 1,3-Bis(1-chloro-1-hexylheptyl)benzene: The crude
1,3-bis(1-hydroxy-1-hexylheptyl)benzene (34.8 g, 73.3 mmol if
pure) was treated with HCl gas in the presence of CaCl2
powder (ca. 50 g) in CH2Cl2 (500 mL) to give 1,3-bis(1-chloro-
1-hexylheptyl)benzene was obtained as a brown oil (35.0 g,
68.4 mmol, 93% yield if pure), which was used for the next
1
yield): mp 86-88 °C. H NMR (CDCl3): ¤ 0.85 (t, J = 7.3 Hz,
12H, CH3), 0.95-1.31 (m, 20H, CH2 and CH3), 1.52-1.60
(m, 4H, CH2), 1.89 (s, 4H, CH2), 1.95-2.02 (m, 4H, CH2), 6.62
(s, 1H, ArH); 13C NMR (CDCl3): ¤ 15.0, 18.5, 32.2, 41.0,
42.0, 51.2, 53.4, 115.8, 117.7, 143.9, 154.8. HRMS (EI)
Calcd for C28H4579Br: 460.2705. Found: 460.2686. Anal.
Calcd for C28H45Br: C, 72.86; H, 9.83%. Found: C, 72.81;
H, 9.98%.
Preparation of MsHind-Br (Dispiro[cyclohexane-1,3¤-(4¤-
bromo-1¤,1¤,7¤,7¤-tetramethyl-s-hydrindacene)-5¤,1¤¤-cyclo-
hexane]). This compound was prepared from 1-bromo-3,5-
bis(1-chloro-1-methylethyl)benzene (26.2 g, 85 mmol), methyl-
enecyclohexane (17.9 g, 0.19 mol), and BCl3 (1.0 M solution
in CH2Cl2, 15 mL, 15 mmol) in CH2Cl2 (500 mL), and was
isolated as colorless crystals by recrystallization from acetone
(10.9 g, 25 mmol, 30% yield): mp 230 °C (sublimation).
1H NMR (CDCl3): ¤ 1.20-1.69 (m, 28H, CH2 and CH3), 1.99
(s, 4H, CH2), 2.70-2.77 (m, 4H, CH2), 6.77 (s, 1H, ArH);
13C NMR (CDCl3): ¤ 23.4, 25.7, 32.4, 35.0, 41.7, 50.7, 52.5,
116.2, 117.4, 146.1, 154.3. HRMS (EI) Calcd for C26H3779Br:
428.2079. Found: 428.2063. Anal. Calcd for C26H37Br: C,
72.71; H, 8.68%. Found: C, 72.42; H, 8.75%.
1
reaction without further purification. H NMR (CDCl3): ¤ 0.84
(t, J = 6.9 Hz, 12H, CH3), 1.10-1.42 (m, 32H, CH2), 2.08-2.15
(m, 8H, CH2), 7.23-7.31 (m, 1H, ArH), 7.36-7.40 (m, 2H,
ArH), 7.51 (s, 1H, ArH).
(3) EHind-H (1,1,7,7-Tetraethyl-3,3,5,5-tetrahexyl-s-hy-
drindacene): This compound was prepared similar to Eind-H
starting from 1,3-bis(1-chloro-1-hexylheptyl)benzene (35.0 g,
68.4 mmol if pure), 2-ethyl-1-butene (13.2 g, 157 mmol), and
BCl3 (1.0 M solution in CH2Cl2, 34 mL, 34 mmol) in CH2Cl2
(300 mL), and was isolated as a light yellow oil (32.3 g,
53.2 mmol, 78% yield if pure). The crude product was used
for the next reaction without further purification. 1H NMR
(CDCl3): ¤ 0.80 (t, J = 7.4 Hz, 12H, CH3), 0.87 (t, J =
6.9 Hz, 12H, CH3), 1.11-1.32 (m, 32H, CH2), 1.42-1.69 (m,
16H, CH2), 1.79 (s, 4H, CH2), 6.63 (s, 1H, ArH), 6.65 (s, 1H,
ArH); 13C NMR (CDCl3): ¤ 9.4, 14.3, 22.9, 25.0, 30.4, 32.1,
33.2, 41.7, 46.7, 48.6, 49.1, 118.9, 119.0, 147.6, 148.4.
(4) HEind-Br: The reaction of EHind-H (32.3 g, 53.2 mmol
if pure) with bromine (54.5 mL, 1.06 mol) in triethyl phosphate
(300 mL) at 35 °C for 2 days gave a mixture of regioisomers,
HEind-Br and EHind-Br, in ca. 4:1 ratio as estimated by
1H NMR spectrum. The major product HEind-Br was isolated
as colorless crystals by recrystallization from hexane/EtOH
(10.5 g, 15.3 mmol, 10% yield for 4 steps): mp 87 °C. 1H NMR
(CDCl3): ¤ 0.77 (t, J = 7.3 Hz, 12H, CH3), 0.87 (t, J = 6.9 Hz,
12H, CH3), 1.13-1.31 (m, 32H, CH2), 1.43-1.50 (m, 4H, CH2),
1.54-1.61 (m, 4H, CH2), 1.77-1.86 (m, 8H, CH2), 1.92-2.01
(m, 4H, CH2), 6.60 (s, 1H, ArH); 13C NMR (CDCl3): ¤ 9.5,
14.2, 22.9, 24.9, 30.4, 31.2, 32.1, 41.5, 44.4, 47.7, 53.5, 118.2,
118.7, 144.8, 152.6. HRMS (EI) Calcd for C44H7779Br:
684.5209. Found: 684.5199. Anal. Calcd for C44H77Br: C,
77.04; H, 11.31%. Found: C, 77.14; H, 11.46%.
Preparation of 2-Propyl-1-pentene. To a suspension of
1,1-dichloroethene (25.0 g, 0.26 mol) and [NiCl2(dppp)]72,73
(700 mg, 1.29 mmol) in Et2O (100 mL) was dropwise added
to a solution of propylmagnesium chloride (2.0 M solution in
Et2O, 270 mL, 0.54 mol) at 0 °C. After the mixture was
vigorously stirred for 1 day at room temperature, the resulting
suspension was quenched with a dilute HCl aq. After the
organic layer was separated, the aqueous layer was extracted
with Et2O. The combined organic layer was washed with water
and brine, and dried over Na2SO4. The mixture was distilled at
atmospheric pressure to give 2-propyl-1-pentene as a colorless
oil (bp 117 °C) (9.30 g, 82.9 mmol, 32% yield): 1H NMR
(CDCl3): ¤ 0.88 (t, J = 7.4 Hz, 6H, CH3), 1.38-1.47 (m, 4H,
CH2), 1.96 (t, J = 7.8 Hz, 4H, CH2), 4.68 (s, 2H, C=CH2);
13C NMR (CDCl3): ¤ 13.8, 20.9, 38.2, 108.6, 149.8.
Preparation of MPhind-Br (4-Bromo-1,1,7,7-tetrameth-
yl-3,3,5,5-tetraphenyl-s-hydrindacene).75
This compound
was prepared from 1-bromo-3,5-bis(1-chloro-1-methylethyl)-
benzene (4.00 g, 13.0 mmol), 1,1-diphenylethene (6.18 g, 34.3
mmol), and BCl3 (1.0 M solution in CH2Cl2, 13 mL, 13 mmol)
in CH2Cl2 (100 mL). During the course of the Friedel-Crafts
reaction, the self-dimerization of 1,1-diphenylethene also took
place to give 1-methyl-1,3,3-triphenylindane as a side product.
After the removal of 1-methyl-1,3,3-triphenylindane by
Kugelrohr distillation (100-130 °C/0.1 mmHg), MPhind-Br
was isolated as colorless crystals by recrystallization from
acetone/hexane (2.05 g, 3.43 mmol, 26% yield): mp 270 °C
1
(sublimation). H NMR (CDCl3): ¤ 1.33 (s, 12H, CH3), 2.91
(s, 4H, CH2), 7.07 (s, 1H, ArH), 7.12-7.24 (m, 20H, ArH);
13C NMR (CDCl3): ¤ 29.9, 42.8, 62.8, 64.6, 115.5, 124.0,
125.7, 127.4, 129.6, 146.0, 146.2, 155.7. HRMS (EI) Calcd
for C40H3779Br: 596.2079. Found: 596.2075. Anal. Calcd for
C40H37Br: C, 80.39; H, 6.24%. Found: C, 80.26; H, 6.24%.
Preparation of MsFluind-Br (Dispiro[fluorene-9,3¤-(4¤-
bromo-1¤,1¤,7¤,7¤-tetramethyl-s-hydrindacene)-5¤,9¤¤-fluo-
rene]).52 This compound was prepared from 1-bromo-3,5-
bis(1-chloro-1-methylethyl)benzene (3.10 g, 10.0 mmol), di-
benzofulvene74 (3.61 g, 20.3 mmol), and BCl3 (1.0 M solution
in CH2Cl2, 10 mL, 10 mmol) in CH2Cl2 (200 mL), and was
isolated as a light yellow crystalline powder by recrystallization
from CH2Cl2/MeOH (4.52 g, 7.61 mmol, 76% yield): mp
1
274 °C (sublimation). H NMR (CDCl3): ¤ 1.56 (s, 12H, Me),
2.46 (s, 4H, CH2), 7.03-7.05 (m, 4H, ArH), 7.08-7.13 (m, 4H,
ArH), 7.15-7.20 (m, 4H, ArH), 7.16 (s, 1H, ArH), 7.49-7.52
(m, 4H, ArH); 13C NMR (CDCl3): ¤ 32.6, 43.3, 56.4, 63.7,
115.4, 118.0, 119.3, 123.6, 126.6, 127.3, 140.7, 143.0, 153.0,
156.9. Anal. Calcd for C40H33Br: C, 80.94; H, 5.60%. Found:
C, 80.87; H, 5.98%.
Preparation of MPind-Br (4-Bromo-1,1,7,7-tetramethyl-
3,3,5,5-tetrapropyl-s-hydrindacene). This compound was
prepared from 1-bromo-3,5-bis(1-chloro-1-methylethyl)ben-

1190 Bull. Chem. Soc. Jpn. Vol. 84, No. 11 (2011) BCSJ AWARD ARTICLE
Table 1. Crystal Data
Eind-Br
EHind-Br
MPind-Br
MsHind-Br
MPhind-Br¢Et2O
Formula
FW
T/K
C28H45Br
461.55
90
C44H77Br
685.97
100
C28H45Br
461.55
100
C26H37Br
429.48
100
C40H37Br¢0.5(C4H10O)
634.67
100
-/¡
Color
Crystal size/mm3
0.71073 (Mo K¡) 0.71073 (Mo K¡)
colorless colorless
0.16 © 0.07 © 0.06 0.40 © 0.20 © 0.10 0.29 © 0.12 © 0.08 0.20 © 0.20 © 0.20 0.20 © 0.10 © 0.10
0.71073 (Mo K¡)
colorless
0.71073 (Mo K¡) 0.71073 (Mo K¡)
colorless colorless
Crystal system
Space group
a/¡
b/¡
c/¡
¡/°
¢/°
£/°
monoclinic
C2/c (#15)
20.140(4)
8.6661(18)
15.204(3)
90
111.377(3)
90
2471.1(9)
4
orthorhombic
Pbcn (#60)
20.262(4)
8.9372(17)
22.399(4)
90
triclinic
P1 (#2)
triclinic
P1 (#2)
triclinic
P1 (#2)
ꢀ
ꢀ
ꢀ
8.4274(13)
11.8851(17)
14.588(2)
74.611(9)
80.232(11)
70.911(9)
1325.8(3)
2
6.3529(12)
8.5568(16)
20.213(4)
83.182(6)
85.701(6)
79.568(5)
1071.4(4)
2
8.8274(17)
13.267(2)
15.267(3)
105.015(3)
106.783(2)
91.205(2)
1644.4(5)
2
90
90
V/¡
Z
DX/Mg m
4056.1(13)
4
1.123
¹3
1.241
1.675
1.156
1.561
1.331
1.932
1.272
1.280
¹1
®/mm
1.041
Measured reflections
32118
35782
16729
10088
22602
Unique reflections (Rint) 3920 (0.050)
Reflections [I > 2·(I)] 3456
4651 (0.037)
4347
7646 (0.043)
5137
4865 (0.053)
4028
8665 (0.033)
7041
Refined parameters
R(F) [I > 2·(I)]
wR(F2) (all data)
S
145
248
281
0.0470
0.1088
1.007
245
0.0441
0.1042
1.041
483
0.0372
0.0864
1.043
0.0588
0.1309
1.156
0.0800
0.1651
1.322
¹3
(¦r)min,max/e ¡
¹0.71, 0.98
¹0.72, 0.52
¹0.49, 0.66
¹0.81, 1.42
¹0.31, 0.70
X-ray Crystallography.
The crystallographic data are
Data Centre, 12, Union Road, Cambridge, CB2 1EZ, U.K.;
Fax: +44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk).
summarized in Table 1. Single crystals suitable for X-ray
diffraction were obtained from hexane for Eind-Br as colorless
blocks, from EtOH for HEind-Br as colorless blocks, from
acetone for MPind-Br and MsHind-Br as colorless blocks, and
from CDCl3/Et2O for MPhind-Br as colorless blocks. The
crystals were immersed in Paraton-N oil on a nylon loop or
MicroMount· and mounted on a Rigaku AFC-8 diffractometer
with a Saturn70 CCD detector (for Eind-Br and MPind-Br), or
a Rigaku AFC-10 diffractomter with a Saturn724+ CCD
detector (for MPhind-Br, MsHind-Br, and HEind-Br) using
graphite-monochromated Mo K¡ radiation (- = 0.71073 ¡).
The integration and scaling of the diffraction data were carried
out using the program CrystalClear.76 Lorentz-polarization and
absorption corrections were also performed. All structures
were solved by direct methods (SIR9277 for MsHind-Br and
SIR200478 for others), and refined on F2 by the full-matrix
least-squares method (SHELXL-9779). The anisotropic atomic
displacement parameters were applied to all non-hydrogen
atoms. The hydrogen atoms were located on difference Fourier
maps for Eind-Br, and placed on calculated positions for the
others. The positions of the hydrogen atoms were refined by
applying riding models.
We thank the Ministry of Education, Culture, Sports, Science
and Technology of Japan for the Grant-in-Aid for Specially
Promoted Research (No. 19002008). We also thank Dr. Yayoi
Hongo for her kind help with the mass spectrometry.
References
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A. G. Brook, F. Abdesaken, B. Gutekunst, G. Gutekunst,
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R. West, M. J. Fink, J. Michl, Science 1981, 214, 1343.
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R. Okazaki, R. West, Adv. Organomet. Chem. 1996, 39, 231.
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V. Y. Lee, A. Sekiguchi, Organometallics 2004, 23, 2822.
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11 R. C. Fischer, P. P. Power, Chem. Rev. 2010, 110, 3877.
12 P. P. Power, Nature 2010, 463, 171.
The crystallographic data have been deposited with the
Cambridge Crystallographic Data Centre: Deposition number
CCDC-789716, -789717, -789718, -789719, -789720, and
-780798 for Eind-Br, HEind-Br, MPind-Br, MsHind-Br,
MPhind-Br, and MsFluind-Br, respectively. Copies of the data
can be obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html (or from the Cambridge Crystallographic
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