Efficient and Selective Synthesis of Crownopaddlanes Possessing Two Cyclobutane Rings and Exclusive Complexation of Lithium

Article abstract of DOI:10.1021/jo9801521

A new type of crown compounds (crownopaddlanes) bearing two cyclobutane rings were efficiently and selectively prepared by means of intramolecular [2 + 2] photocycloaddition of appropriate styrene derivatives, which was successfully carried out in cyclohexane under irradiation through a Pyrex filter. Crownopaddlanes 4a, 5, and 6 exclusively and quantitatively extracted Li⁺ on the solid-liquid extraction. Upon the competitive extraction, 4a showed the highest selectivity toward Li⁺ over Na⁺ and K⁺ (Li⁺/Na⁺ = 610, Li⁺/K⁺ = 976). The structural factors working in the complexation of the crownopaddlane were examined by X-ray crystallographic analysis.

Full text of DOI:10.1021/jo9801521

J . Org. Chem. 1998, 63, 5791-5796
5791
Efficien t a n d Selective Syn th esis of Cr ow n op a d d la n es P ossessin g
Tw o Cyclobu ta n e Rin gs a n d Exclu sive Com p lexa tion of Lith iu m
Seiichi Inokuma, Masashi Takezawa, Hiroko Satoh, Yosuke Nakamura, Takashi Sasaki, and
J un Nishimura*
Department of Chemistry, Gunma University, 1-5-1 Tenjin-cho, Kiryu 376-8515, J apan
Received J anuary 27, 1998
A new type of crown compounds (crownopaddlanes) bearing two cyclobutane rings were efficiently
and selectively prepared by means of intramolecular [2 + 2] photocycloaddition of appropriate
styrene derivatives, which was successfully carried out in cyclohexane under irradiation through
a Pyrex filter. Crownopaddlanes 4a , 5, and 6 exclusively and quantitatively extracted Li+ on the
solid-liquid extraction. Upon the competitive extraction, 4a showed the highest selectivity toward
Li+ over Na+ and K+ (Li+/Na+ ) 610, Li+/K+ ) 976). The structural factors working in the
complexation of the crownopaddlane were examined by X-ray crystallographic analysis.
In tr od u ction
Ring closure of linear precursors to crown ethers is
entropically unfavorable, and their polymerization often
cannot be avoided. Some improvements, such as the
template effect1-3 and/or high-dilution techniques,4,5 have
increased the yield of cyclization products. These im-
provements usually require some additional workup,
except for Okahara cyclization.6 Recently, we developed
a new high-yielding photocyclization for crown com-
pounds in which the template effect and high dilution
are not crucial. Thus, many “crownophanes”7 possessing
both cyclic polyether and cyclophane moieties have been
prepared in high yields (up to 95%) by the [2 + 2]
photocycloaddition of R,ω-bis(vinylphenyl)oligo(oxyeth-
ylenes). Quite astonishingly, this reaction was accom-
plished even with a relatively high concentration of
precursor olefins (100 mM). This approach has been
applied to the synthesis of sophisticated ionophoric
materials.
In previous extraction and liquid membrane transport
experiments, it has been revealed that crownophanes
1b was concluded to be due to its unique structure,10 and
the main cause of the reduced Li+ selectivity of 212 and
313 has been attributed to 2:1 (host:guest) complexation
with larger cations such as Na+ or K+. Therefore, if one
can strongly prevent the formation of the 2:1 (host:guest)
sandwich complex by adding structural factors to 1b, one
should be able to greatly increase its Li+ selectivity.
Generally, to increase the selectivity of crown ethers, one
introduces peripheral bulky groups.14-16 Another struc-
tural modification of host molecules which improves the
selectivity involves rigidifying or preorganizing them for
particular guest molecules. For example, a spherand
modified in this manner showed enormous Li+ affinity
have specific characteristics in host-guest interactions
with many kinds of metal cations8 and organic com-
pounds.9 Among the crownophanes, the prototypical
crownophane 1b with five ethereal oxygen atoms exhib-
ited a greater complexing ability toward Li+ than the
conventional lithiophilic 12-crown-4 (2) and dibenzo-14-
crown-4 (3) by solid-liquid extraction10 and liquid mem-
brane transport.11 The intriguing high lithiophilicity of
(1) Dale, J .; Kristiansen, P. O. J . Chem. Soc., Chem. Commun. 1971,
670.
(2) Greene, R. N. Tetrahedron Lett. 1972, 1793.
(3) Chastrette, M.; Chastrette, F. J . Chem. Soc., Chem. Commun.
1973, 534.
(4) Pedersen, C. J . J . Am. Chem. Soc. 1967, 89, 7017.
(5) Dietrich, B.; Lehn, J . M.; Sauvage, J . P. Tetrahedron Lett. 1969,
2885.
(6) Kuo, P.-L.; Kawamura, N.; Miki, M.; Okahara, M. Bull. Chem.
Soc. J pn. 1980, 53, 1689.
(11) Inokuma, S.; Katoh, R.; Yamamoto, T.; Nishimura, J . Chem.
Lett. 1991, 1751.
(12) Miyazaki, T.; Yanagida, S.; Itoh, A.; Okahara, M. Bull. Chem.
Soc. J pn. 1982, 55, 2005.
(7) Inokuma, S.; Sakai, S.; Nishimura, J . Top. Curr. Chem. 1994,
172, 87.
(8) Inokuma, S.; Sakai, S.; Katoh, R.; Nishimura, J . Bull. Chem. Soc.
J pn. 1994, 67, 1462.
(13) Suzuki, K.; Yamada, H.; Sato, K.; Watanabe, K.; Hisamoto, H.;
Tobe, Y.; Kobiro, K. Anal. Chem. 1993, 65, 3404.
(14) Kobiro, K.; Matsuoka, T.; Takada, S.; Kakiuchi, K.; Tobe, Y.;
Odaira, Y. Chem. Lett. 1986, 713.
(9) Inokuma, S.; Sakai, S.; Yamamoto, T.; Nishimura, J . J . Membr.
Sci. 1994, 97, 175.
(10) Inokuma, S.; Yamamoto, T.; Nishimura, J . Tetrahedron Lett.
1990, 31, 97.
(15) Faulkner, S.; Kataky, R.; Parker, D.; Teasdale, A. J . Chem. Soc.,
Perkin Trans. 2 1995, 1761.
(16) Kobiro, K.; Kaji, M.; Tsuzuki, S.; Tobe, Y.; Tuchiya, Y.; Nae-
mura, K.; Suzuki, K. Chem. Lett. 1995, 831.
S0022-3263(98)00152-2 CCC: $15.00 © 1998 American Chemical Society
Published on Web 08/05/1998

5792 J . Org. Chem., Vol. 63, No. 17, 1998
Inokuma et al.
Sch em e 1
yield of 4 and 9 was only 50%. In such cases, we usually
obtained some polymeric material which was not char-
acterized.
Generally, nonpolar solvents favored the photoreaction.
An extraordinarily high yield was obtained in the photo-
reaction of olefin 8a in cyclohexane (up to 93%), which
was comparable to those of prototypical crownophanes
1a ,b.10 This efficiency was attributed to steric effects due
to the high flexibility of C-O bonds in the linkages
between two phenoxy groups.20
The photoreaction yields are clearly dependent on the
polarity of the solvents and on the duration of irradiation.
The time course of the reaction of 8b is illustrated in
Figure 1. In cyclohexane, the yield of crownopaddlane
4b smoothly increased with irradiation time and reached
a maximum (up to 97%) at 20 min. At the same time,
the conversion approached 100% and 9b , which is
considered to be an intermediate of 4b, completely
disappeared. On the other hand, in acetonitrile (MeCN),
although the consumption rate of 8b was similar to that
in cyclohexane, the maximum yield of 4b was much lower
than that in cyclohexane and the photostability of the
product in this polar solvent was remarkably low. Fur-
thermore, intermediate 9b seemed to be long-lived, in
contrast to that in cyclohexane. Thus, double photo-
cyclization proceeds efficiently in nonpolar solvents such
as cyclohexane, benzene, and toluene. However, the yield
in polar solvents such as MeCN was slightly improved
by the addition of alkali metal salts (entries 6, 8, and
14-16 in Table 1). The template effect plays a role in
the polar solvents and seems to increase product stabil-
ity.7
Syn th esis of Cr ow n op a d d la n es w ith a Secon d a r y
Liga tin g Site. Lariat-type crownopaddlane 5 was pre-
pared following a sequence similar to that for 4. Photo-
cyclization of the precursor tetraolefin was carried out
in cyclohexane. The yield of crownopaddlane 6 with an
oxetane moiety was slightly lower than that of 4. Com-
pound 6 was readily converted to lariat-type crowno-
paddlane 5.
Sin gle Extr a ction of Alk a li Meta l Th iocya n a tes
in to CH2Cl2 by Cr ow n op a d d la n es. The complexing
ability of crownophanes toward alkali metal cations was
evaluated by solid-liquid extraction and compared with
those of 1a ,b, 2, and 3. This extraction is a simple
method for measuring the net complexing ability of
ligands since the process does not include dehydration
from cations in an aqueous phase. The results of the
extraction experiments with crownopaddlanes are sum-
marized in Table 2 together with those of reference crown
compounds.
(∆G ) 17 kcal mol-1).17,18 However, these structural
modifications often require multistep syntheses which
involve some tedious procedures and meager total yields.
Accordingly, we were prompted to prepare a highly
lithiophilic ionophore which optimized the structure of
1b by [2 + 2] photocycloaddition. Hence, we designed
“crownopaddlanes” 4 and 5 with two cyclobutane rings
on the basis of the following criteria. First, they must
have 12- to 14-membered rings with four ethereal oxygen
atoms to accept Li+. Second, they must have large
substituents to prevent 2:1 (host:guest) tetrahedrally
coordinated complexation with larger cations such as Na+
or K+. Third, they must have sufficiently lipophilic
substituents. Fourth, they preferably should have ad-
ditional ligating groups to improve the binding ability.
In this paper we describe the synthesis and lithiophilic
properties of 4 and 5 as well as some related compounds.
Resu lts a n d Discu ssion
Syn th esis of Cr ow n op a d d la n es. First, we tried to
synthesize crownopaddlanes (4), as shown in Scheme 1.
R,ω-Bis(2,6-dibromophenyl)oligo(oxyethylenes) (7) were
easily prepared by the conventional method and con-
verted to the corresponding tetraolefins (8) by the Stille
reaction.19 These precursor olefins were irradiated in a
variety of solvents with different polarities, as listed in
Table 1.
In most cases, the starting material was almost
completely consumed under irradiation. In some in-
stances, the yields and conversions were almost the same,
while in others they were considerably different. For
example, in run 7, the conversion was 96% but the total
Crownopaddlane 4a quantitatively and exclusively
extracted Li+. This selectivity was not attained with
conventional crown ethers 2 and 3: the former extracted
not only Li+ but also Na+ and K+ due to the formation of
2:1 sandwich complexes, as reported previously,12 while
the latter, which is more lithiophilic than 2,21 extracted
quite a large amount of Na+ as well as Li+. According
to a framework examination using a space-filling model,
the cavity size of 4a (ca. 1.2 Å) is quite suitable for Li+.
Furthermore, the two bulky cyclobutane blades attached
to the aromatic nuclei can effectively prevent it from
forming a 2:1 sandwich complex.
(17) Cram, D. J .; Kaneda, T.; Helgeson, R. C.; Lein, G. M. J . Am.
Chem. Soc. 1979, 101, 6752.
(18) Kaneda, T.; Umeda, S.; Tanigawa, H.; Misumi, S. J . Am. Chem.
Soc. 1985, 107, 4802.
(19) McKean, D. R.; Parrinello, G.; Renaldo, A. F.; Stille, J . K. J .
Org. Chem. 1987, 52, 422.
(20) Nakamura, Y.; Fujii, T.; Inokuma, S.; Nishimura, J . J . Phys.
Org. Chem. 1998, 11, 79-83.
(21) Olsher, U. J . Am. Chem. Soc. 1982, 104, 4006.

Crownpaddlanes Possessing Two Cyclobutane Rings
Ta ble 1. P r ep a r a tion of Cr ow n op a d d la n es 4 a n d 9a
reaction conditions
addnc
J . Org. Chem., Vol. 63, No. 17, 1998 5793
yielde (%)
entry
olefin
solventb
timed/min
conversione (%)
4
9
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
8a
8a
8a
8a
8a
8a
8a
8a
8b
8b
8b
8b
8b
8b
8b
8b
cyclohexane
benzene
toluene
MeOH
MeCN
MeCN
MeCN
MeCN
cyclohexane
benzene
toluene
MeOH
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
100
94
99
97
94
85
96
98
100
96
95
96
94
100
97
97
84 (93)f
61
87
56
32
6 (6)f
15
3
14
25
17
32
26
LiBF4
NaBF4
KBF4
38
18
54
92 (93)f
71
7 (6)f
12
9
15
30
1
18
16
53
58
39
67
75
41
MeCN
MeCN
MeCN
MeCN
LiBF4
NaBF4
KBF4
a
A 400 W high-pressure mercury lamp was set at the distance of 5 cm from Pyrex tubes (15 mL) which contained the reaction mixture
(10 mL) under a nitrogen atmosphere at room temperature. 2 mM. c 60 mM. Around maximum yields (in 15 min). e Determined by
b
d
HPLC and 1H NMR spectroscopy. f Isolated yield under different conditions (see Experimental Section).
Ta ble 2. Sin gle Extr a ction of Meta l Th iocya n a te w ith
a
Cr ow n op a d d la n es in CH2Cl2
percent extraction
ligand
Li+
Na+
K+
1a
1b
2
0
100
100
100
99
89
100
92
0
24
59
45
0
94
65
0
0
28
58
0
3
4a
4b
4c
5
0
42
70
0
a
Extraction conditions: Solid phase, a pulverized metal thio-
cyanate (1.5 × 10-3 mol). Liquid phase, [ligand] ) 5.0 × 10-2
M
(CH2Cl2, 1 mL).
the order of extractability was Li+ ∼ Na+ > K+. Com-
pound 4c with six ethereal oxygen atoms also extracted
all of the cations examined in the order Li+ > Na+ ∼ K+.
These results with 4b,c suggest that their cavities are
still smaller than those of conventional crown ethers but
not small enough to bind Li+ selectively.
Crownopaddlane 6 with an oxetane residue, which has
a cavity corresponding formally to that of 13-crown-4 or
14-crown-4, was practically insoluble in CH2Cl2 and could
not be used as an extractant. To increase the solubility
of 6 and also to increase the number of ligating sites, the
oxetane moiety was cleaved with acid catalyst in metha-
nol (MeOH) to afford crownopaddlane 5. It became
soluble and showed high selectivity and efficiency toward
Li+, like 4a .
Sin gle Extr a ction of Alk a li Meta l Th iocya n a tes
in to CHCl3 by Cr ow n op a d d la n es. In general, extrac-
tion coefficients depend on the solvents used in extraction
systems due to the solubility and/or distribution con-
stants of complexes formed from ligands and substrates.
In a liquid membrane transport system, changing the
solvent from CH2Cl2 to CHCl3 results in a different
transport rate of alkali metal cations.22 To examine
solvent effects on the extraction and to evaluate the
complexing ability of crownopaddlane 6, which was
insoluble in CH2Cl2, solid-liquid extraction was carried
out in CHCl3. The results are shown in Table 3.
All of the ligands showed exclusive selectivity toward
Li+. The efficiency order was 4a < 6 < 5, which can be
F igu r e 1. Time course of the photoreaction of 8b in (a)
acetonitrile and (b) cyclohexane.
Moreover, the selectivity showed by 4a is considerably
different from those of paracrownophanes 1. Ether 1a ,
which is similar to 4a , did not extract any cations at all,
while crownophane 1b, which has five ethereal oxygen
atoms, exhibited relatively high Li+ affinity.10 This is
because 1a has a cyclic ether ring that is widely expanded
by two benzene rings and is too rigid to bind any metal
cations, even the small Li+. Thus, 4a strongly forces both
ends of the ether linkage close together to accept the
small cation.
On the other hand, crownopaddlane 4b with five
ethereal oxygen atoms extracted Li+, Na+, and K+, and
(22) Yoshida, S.; Watanabe, T. Bull. Chem. Soc. J pn. 1990, 63, 3508.

5794 J . Org. Chem., Vol. 63, No. 17, 1998
Inokuma et al.
Ta ble 3. Sin gle Extr a ction of Meta l Th iocya n a te w ith
a
Cr ow n op a d d la n es in CHCl3
percent extraction
ligand
Li+
Na+
K+
4a
5
6
50
100
87
0
0
0
0
0
0
a
Extraction conditions: Solid phase, a pulverized metal thio-
cyanate (1.5 × 10-3 mol). Liquid phase, [ligand] ) 5.0 × 10-2
M
(CHCl3, 1 mL).
Ta ble 4. Com p etitive Extr a ction of Meta l Th iocya n a te
w ith Cr ow n op a d d la n esa
percent extraction
selectivity
ligand
Li+
Na+
K+
Li+/Na+
Li+/K+
3
4a
5
31.9
48.8
72.0
0.28
0.08
0.84
0.16
0.05
0.12
114
610
86
199
976
600
F igu r e 2. Crystal structure of crownopaddlane 4a .
a
Extraction conditions: Solid phase, a pulverized metal thio-
cyanate (1.5 × 10-3 mol in each). Liquid phase, [ligand] ) 5.0 ×
10-2 M (CH2Cl2, 10 mL).
Con clu sion
Crownopaddlanes were conveniently synthesized by
intramolecular [2 + 2] photocycloaddition of the corre-
sponding divinylbenzene derivatives. The host molecule
with four ethereal oxygen atoms showed excellent Li+
selectivity and great efficiency in solid-liquid extraction
due to its unique structure.
explained as follows: crownopaddlane 6 has a more
suitable cavity for Li+ than 4a , and lariat crowno-
paddlane 5 has an additional ligating site for stronger
complexation.
Com p et it ive E xt r a ct ion of Alk a li Met a l Th io-
cya n a tes by Cr ow n op a d d la n es. Considerable differ-
ences are often found between single and competitive
extraction23,24 and the selectivity of competitive extraction
is important from a practical point of view because the
latter indicates an absolute complexing selectivity for
cations contained together in the system.
Exp er im en ta l Section
Gen er a l. 1H NMR spectra were taken at 500 MHz using
tetramethylsilane as an internal standard. Elemental analysis
was carried out in the Technical Research Center for Instru-
mental Analysis. Cyclohexane, benzene, and toluene were
purified by distillation over Na after prolonged reflux under
N2. Guaranteed reagent grade MeCN, MeOH, and CH2Cl2
were distilled before use.
Competitive extraction was carried out for some rep-
resentative ligands with Li+ affinity. As shown in Table
4, the order of the efficiency of Li+ extraction by crown
compounds with four ethereal oxygen atoms was 3 < 4a
< 5. With regard to selectivity, host 4a exhibited the
highest selectivity toward Li+ over Na+ and K+ (Li+/Na+
) 610, Li+/K+ ) 976) among the compounds. The
selectivity of 5 toward Li+ over Na+ was lower than that
of 4a . This is considered to be due to the binding of Na+
by intramolecular cooperation between the cyclic poly-
ether part and the additional ligating site, namely, a
methoxy group.
Paracrownophane 110 and dibenzo-14-crown-4 319 were
prepared by the method reported previously. Reagent grade
12-crown-4 2 was used without further purification. The
commercially available highest grades of LiSCN, NaSCN, and
KSCN were used. All aqueous solutions were prepared with
distilled, deionized water.
P r ep a r a tion of r,ω-Bis(2,6-d ivin ylp h en yl)oligo(oxy-
eth ylen es) 7a -c. To a suspension of CsF (50.0 g, 329 mmol)
in 100 mL of MeCN, a mixture of 2,6-dibromophenol (30.0 g,
11.9 mmol) and corresponding oligo(ethylene glycol) ditosylate
(4.0 mmol) in MeCN (70 mL) was added at room temperature
for 1 h under N2. The mixture was stirred at reflux temper-
ature for 5 h. The suspension was filtered, and the filtrate
was concentrated in vacuo. The residue was dissolved in
CH2Cl2 (1 L) and then successively washed with 10% aqueous
NaOH and water and dried over MgSO4. The organic layer
was evaporated under reduced pressure to give the desired
compounds.
Cr ysta l Str u ctu r e of Cr ow n op a d d la n e 4a . The
specific complexation feature mentioned above was ex-
amined by X-ray crystallographic analysis. Since we
could not prepare a single crystal of the complex between
4a and lithium salts such as LiSCN, LiBF4, etc., in
acetone, we only analyzed a single crystal of 4a .
Com p ou n d 7a : Yield, 91%; mp 75-76 °C. 1H NMR
(CDCl3): δ 7.50 (d, J ) 8.2, 4H), 6.85 (t, J ) 8.1, 2H), 4.22-
4.19 (m, 4H), 3.98-3.95 (m, 4H), 3.82 (s, 4H). Anal. Calcd
for C18H18O4Br4: C, 34.99; H, 2.94. Found: C, 35.14; H, 3.01.
Com p ou n d 7b: Yield, 97%; viscous liquid. 1H NMR
(CDCl3): δ 7.49 (d, J ) 7.9, 4H), 6.85 (t, J ) 8.1, 2H), 4.24-
4.16 (m, 4H), 3.99-3.91 (m, 4H), 3.83-3.67 (m, 8H). Anal.
Calcd for C20H22O5Br4: C, 36.29; H, 3.35. Found: C, 36.12;
H, 3.30.
As illustrated in Figure 2, the solid-state structure of
4a was determined to exhibit structural preorganization
upon complexation with the smallest group I metal, Li+;
i.e., the polyether ring was curved toward one of the
cyclobutane rings, and the cavity diameter of 4a was ca.
1.22 Å, which is quite appropriate for binding to Li+.
Furthermore, the cyclobutane blades of 4a may act as a
steric barrier to 2:1 sandwich complexation. These
results suggest that these factors act cooperatively in the
solution and result in the quantitative and exclusive
extraction of Li+.
Com p ou n d 7c: Yield, 78%; viscous liquid. 1H NMR
(CDCl3): δ 7.49 (d, J ) 7.9, 4H), 6.85 (t, J ) 8.1, 2H), 4.21-
4.17 (m, 4H), 3.96-3.91 (m, 4H), 3.80-3.74 (m, 4H), 3.72-
3.66 (m, 8H). Anal. Calcd for C22H26O6Br4: C, 37.42; H, 3.71.
Found: C, 37.47; H, 3.79.
P r ep a r a tion
of r,ω-Bis(Divin ylp h en yl)oligo(oxy-
(23) Strzelbiki, J .; Bartsch, R. A. Anal. Chem. 1981, 53, 1894.
(24) Strzelbiki, J .; Bartsch, R. A. Anal. Chem. 1981, 53, 2247.
eth ylen es) 8a -c. A solution of R,ω-bis(2,6-dibromophenyl)-

Crownpaddlanes Possessing Two Cyclobutane Rings
J . Org. Chem., Vol. 63, No. 17, 1998 5795
oligo(oxyethylenes) (20.2 mmol), tributylvinylstannane (3.90
g, 120 mmol), Pd(PPh3)4 (5.60 g, 4.86 mmol), and 2,6-di-tert-
butyl-4-methylphenol (15 mg) in toluene (300 mL) was heated
to reflux for 20 h. After the mixture was cooled to ambient
temperature, a large excess of 1.2 M aqueous KF solution was
added, and the resulting mixture was stirred overnight at the
same temperature. The organic layer was separated from the
sludge and aqueous layer and then dried over MgSO4. The
concentrated crude material was purified by column chroma-
tography (SiO2, a gradient mixed solution of benzene and
acetone) to afford the tetravinyl derivatives.
and dried over MgSO4. The organic layer was evaporated
under reduced pressure, and the residue was purified by
column chromatography (SiO2, a gradient solution of benzene
and ethyl acetate) to give the desired tetrabromide, a deriva-
1
tive of 7 in Scheme 1. Yield, 33%. H NMR (CDCl3): δ 7.51
(d, J ) 8.2, 4H), 6.86 (t, J ) 8.1, 2H), 4.52 (s, 4H), 4.24-4.18
(m, 4H), 3.96-3.90 (m, 4H), 3.82 (s, 4H). Anal. Calcd for
C
21H22O5Br4: C, 37.42; H, 3.29. Found: C, 37.65; H, 3.34.
A solution of tetrabromide prepared above (5.91 g, 8.77
mmol), tributylvinylstannane (13.9 g, 43.8 mmol), Pd(PPh3)4
(2.02 g, 1.76 mmol), and 2,6-di-tert-butyl-4-methylphenol (15
mg) in toluene (120 mL) was heated to reflux for 20 h. After
the mixture was cooled to ambient temperature, a large excess
of 1.2 M aqueous KF solution was added, and the resulting
mixture was stirred overnight at the same temperature. The
organic layer was separated from the sludge and aqueous layer
and then dried over MgSO4. The crude material obtained by
evaporation of the filtrate was purified by gel permeation
chromatography (GPC) using CHCl3 as eluent to afford the
tetravinyl derivatives (1.94 g), a derivative of 8 in Scheme 1,
as a pale yellow liquid. Yield, 48%. 1H NMR (CDCl3): δ 7.43
(d, J ) 8.0, 4H), 7.14-7.01 (m, 6H), 5.75 (d, J ) 17.7, 4H),
5.29 (d, J ) 11.3, 4H), 4.57 (s, 4H), 4.01-3.92 (m, 4H), 3.84-
3.72 (m, 8H). Anal. Calcd for C29H34O5: C, 75.30; H, 7.41.
Found: C, 75.67; H, 7.55.
Into a 1 L Pyrex flask equipped with a magnetic stirrer and
N2 inlet was placed 0.33 g (0.71 mmol) of the precursor olefin
dissolved in cyclohexane (700 mL), and N2 was bubbled
through the solution for 30 min. The solution was irradiated
by a 400 W high-pressure Hg lamp. The progress of the
reaction was followed by HPLC. After irradiation for 1.5 h,
the reaction mixture was evaporated. The crude reaction
product was purified by GPC using CHCl3 as eluent to afford
crownopaddlane 6 (0.19 g). Yield, 58%; mp 199-200 °C. 1H
NMR (CDCl3): δ 6.56 (d, J ) 7.3, 4H), 6.47 (t, J ) 7.4, 2H),
4.61 (s, 4H) 4.50-4.39 (m, 4H), 4.13 (s, 4H), 3.75-3.54 (m,
8H), 2.48-2.27 (m, 8H). Anal. Calcd for C29H34O5: C, 75.30;
H, 7.41. Found: C, 75.39; H, 7.38.
P r ep a r a tion of La r ia t Cr ow n op a d d la n e 5. A mixture
of crownopaddlane 6 (0.40 g, 0.87 mmol), MeOH (2.60 g, 81.3
mmol), and H2SO4 (0.05 g) was placed into a 20 mL pressure
bottle. The solution was heated at 130 °C for 5 h. The reaction
mixture was cooled to room temperature and neutralized with
saturated aqueous Na2CO3. The crude reaction product
obtained after evaporation of the filtrate was purified by GPC
using CHCl3 as eluent to afford crownopaddlane 5 (0.23 g).
Yield, 53%; mp 150 °C. 1H NMR (CDCl3): δ 6.57 (d, J ) 7.3,
4H), 6.48 (t, J ) 7.5, 2H), 4.52-4.42 (m, 4H), 3.97-3.51 (m,
16H), 3.43 (s, 3H), 3.09-3.04 (m, 1H), 2.48-2.22 (m, 8H). Anal.
Calcd for C30H38O6: C, 72.85; H, 7.74. Found: C, 72.66; H,
7.85.
Com p ou n d 8a : Yield, 24%; mp 72-73 °C. 1H NMR
(CDCl3): δ 7.44 (d, J ) 8.0, 4H), 7.13-7.06 (m, 6H), 5.75 (d, J
) 17.7, 4H), 5.29 (d, J ) 11.3, 4H), 3.99-3.95 (m, 4H), 3.85-
3.82 (m, 4H), 3.81-3.78 (m, 4H). Anal. Calcd for C26H30O4:
C, 76.82; H, 7.44. Found: C, 76.95; H, 7.39.
Com p ou n d 8b : Yield, 23%; viscous liquid. 1H NMR
(CDCl3): δ 7.44 (d, J ) 7.9, 4H), 7.14-7.04 (m, 6H), 5.74 (d, J
) 18.9, 4H), 5.29 (d, J ) 12.2, 4H), 3.98-3.94 (m, 4H), 3.82-
3.75 (m, 12H). Anal. Calcd for C28H34O5: C, 74.64; H, 7.61.
Found: C, 74.83; H, 7.59.
Com p ou n d 8c: Yield, 58%; viscous liquid. 1H NMR
(CDCl3): δ 7.44 (d, J ) 7.9, 4H), 7.08 (dd, J ) 11.3 and 17.7,
4H), 6.96 (t, J ) 7.5, 2H), 5.75 (d, J ) 17.8, 4H), 5.29 (d, J )
11.2, 4H), 4.09-4.05 (m, 4H), 3.97-3.92 (m, 4H), 3.88-3.84
(m, 4H), 3.81-3.68 (m, 8H). Anal. Calcd for C30H38O6: C,
72.85; H, 7.74. Found: C, 72.97; H, 7.81.
P r ep a r a tion of Cr ow n op a d d la n es 4a -c. Into a 1 L
Pyrex flask with a magnetic stirrer and N2 inlet was placed
2.0 mmol of R,ω-bis(2,6-divinylphenyl)oligo(oxyethylenes) 8
dissolved in cyclohexane (800 mL), and N2 was bubbled
through the solution for 15 min. The solution was irradiated
by a 400 W high-pressure Hg lamp. The progress of the
reaction was followed by HPLC. After irradiation for 5 h, the
solvent was removed by evaporation. The crude reaction
product was purified by column chromatography (SiO2, a
gradient solution of benzene and acetone) to afford the
crownopaddlanes.
Com p ou n d 4a : Yield, 93%; mp 176 °C. 1H NMR (CDCl3):
δ 6.57 (d, J ) 7.6, 4H), 6.48 (t, J ) 7.5, 2H), 4.52-4.48 (m,
4H), 3.98-3.93 (m, 4H), 3.87-3.76 (m, 4H), 3.65-3.55 (m, 4H,),
2.51-2.28 (m, 8H). Anal. Calcd for C26H30O4: C, 76.82; H,
7.44. Found: C, 76.67; H, 7.48.
Com p ou n d 4b: Yield, 93%; mp 143-144 °C. 1H NMR
(CDCl3): δ 6.56 (d, J ) 7.3, 4H), 6.47 (t, J ) 7.5, 2H,), 4.53-
4.44 (m, 4H), 3.89-3.75 (m, 12H), 3.63-3.57 (m, 4H), 2.48-
2.26 (m, 8H). Anal. Calcd for C28H34O5: C, 74.64; H, 7.61.
Found: C, 74.37; H, 7.64.
Com p ou n d 4c: Yield, 29%; mp 85-86 °C. 1H NMR
(CDCl3): δ 6.56 (d, J ) 10.0, 4H), 6.47 (t, J ) 7.5, 2H), 4.52-
4.41 (m, 4H), 3.89-3.51 (m, 20H), 2.46-2.26 (m, 8H). Anal.
Calcd for C30H38O6: C, 72.85; H, 7.74. Found: C, 72.78; H,
7.69.
Solven t a n d Ad d itive Effects on th e P h otocycloa d d i-
tion . The yields for the photocyclizations were measured
under a variety of conditions by using a merry-go-round
apparatus. The 15 mL Pyrex test tubes containing a solution
of the precursor olefin (2 mmol) in a degassed solvent were
set around a 400 W high-pressure Hg lamp at the distance of
5 cm. After irradiation for the prescribed time, the conversion
Compounds 9a ,b were also obtained as byproducts.
Com p ou n d 9a : Yield, 6%; viscous liquid. 1H NMR
(CDCl3): δ 7.23 (d, J ) 9.1, 2H), 7.09 (d, J ) 9.1, 2H), 6.93-
6.81 (m, 4H), 5.61 (d, J ) 18.6, 2H), 5.17 (d, J ) 11.9, 2H),
4.61-4.53 (m, 2H), 3.99-3.68 (m, 12H), 2.54-2.27 (m, 4H).
Anal. Calcd C26H30O4: C, 76.82; H, 7.44. Found: C, 76.77;
H, 7.36.
1
and the yields of products were determined by HPLC and H
NMR spectroscopy.
Com p ou n d 9b : Yield, 6%; viscous liquid. 1H NMR
(CDCl3): δ 7.22 (d, J ) 7.6, 2H), 7.14 (d, J ) 7.6, 2H,), 6.94-
6.60 (m, 4H), 5.60 (d, J ) 17.7, 2H), 5.17 (d, J ) 11.3, 2H),
4.58-4.51 (m, 2H), 3.96-3.71 (m, 16H), 2.54-2.31 (m, 4H).
Anal. Calcd for C28H34O5: C, 74.64; H, 7.61. Found: C, 74.79;
H, 7.58.
P r ep a r a tion of Cr ow n op a d d la n e 6. A mixture of 2,6-
dibromophenol (30.0 g, 11.9 mmol) and 3,3-bis(p-toluenesulfon-
yloxymethyl)oxetane (15.3 g, 30.0 mmol) in dioxane (360 mL)
was added to a suspension of pulverized KOH (7.35 g, 131
mmol) in 100 mL of MeCN at room temperature for 1 h under
N2. The mixture was stirred at reflux temperature for 10 h.
The suspension was filtered, and the filtrate was concentrated
in vacuo. The residue was dissolved in CH2Cl2 (500 mL) and
then successively washed with 10% aqueous NaOH and water
Sin gle Solid -Liqu id Extr a ction of Alk a li Meta l Ca t-
ion s. A CH2Cl2 or a CHCl3 solution of crownophane (5 × 10-2
M, 1.0 mL) and a pulverized metal thiocyanate (1.5 × 10-3
mol) were stirred in a 5.0 mL glass-stoppered test tube with a
ground-glass stopper at ambient temperature (18-20 °C) for
24 h. The organic liquid phase was separated and evaporated.
The extractability of the ligand was evaluated from the
nitrogen content of the residue, which was measured by
elemental analysis.
Com p etitive Solid-Liqu id Extr a ction of Ala k a li Meta l
Ca tion s. A CH2Cl2 solution of crownophane (5 × 10-2 M, 10
mL) and three pulverized metal thiocyanates (1.5 × 10-2 mol
in each) were stirred in a 15 mL glass-stoppered test tube with
a ground-glass stopper at ambient temperature (18-20 °C) for
6 h. The organic liquid phase was separated and evaporated

5796 J . Org. Chem., Vol. 63, No. 17, 1998
Inokuma et al.
in vacuo. The residue was dissolved in 0.1 M HNO3 for
analysis by atomic absorption spectrometry.
counts were accumulated to ensure good counting statistics.
Stationary background counts were recorded on each side of
the reflection. The ratio of peak counting time to background
counting time was 2:1. The diameter of the incident beam
collimator was 1.0 mm, the crystal to detector distance was
235 mm, and the computer controlled detector aperture was
set to 9.0 × 13.0 mm (horizontal × vertical).
Cr ysta llogr a p h ic An a lysis of 4a . A colorless prismatic
crystal of C26H30O4 having approximate dimensions of 0.20 ×
0.20 × 0.30 mm was mounted on a glass fiber. All measure-
ments were made on a diffractometer with graphite mono-
chromated Cu KR radiation.
Cell constants and an orientation matrix for data collection,
obtained from a least-squares refinement using the setting
angles of 25 carefully centered reflections in the range 56.41
< 2θ < 56.99°, corresponded to a primitive triclinic cell with
dimensions: a ) 9.996(3) Å, b ) 14.019(3) Å, c ) 7.535(2) Å,
V ) 1033.4(5) A3, R ) 94.67(2)°, â ) 96.63(3)°, γ ) 98.04(2)°,
V ) 1033.4(5) Å3.
For Z ) 2 and fw ) 406.52, the calculated density is 1.31
g/cm3. On the basis of a statistical analysis of intensity
distribution, and the successful solution and refinement of the
structure, the space group was determined to be: P1h (No. 2).
The data were collected at a temperature of 20 ( 1 °C using
the ω-2θ scan technique to a maximum 2θ value of 120.1°.
The ω scans of several intense reflections, made prior to data
collection, had an average width at half-height of 0.33° with a
takeoff angle of 6.0°. Scans of (1.68 + 0.30 tan θ)° were made
at a speed of 16.0°/min (in ω). The weak reflections (I <
10.0σ(I)) were rescanned (maximum of three scans), and the
Ack n ow led gm en t. This work was partly supported
by a Grant-in-Aid from the Ministry of Education,
Science, Sports, and Culture, J apan.
Su p p or tin g In for m a tion Ava ila ble: Tables listing, for
4a , crystallographic data, atomic coordinates, anisotropic
displacement parameters, bond lengths and angles, torsion
angles, and nonbonded contact distances, text describing data
collection methods, and figures showing an ORTEP of 4a and
elution results for 4a -c, 5, and 6 (28 pages). This material is
contained in libraries on microfiche, immediately follows this
article in the microfilm version of the journal, and can be
ordered from the ACS; see any current masthead page for
ordering information.
J O9801521