Synthesis of the proton-ionizable lariat crown ether and chiral recognition of primary amines

Article abstract of DOI:10.1016/S0040-4020(02)00074-1

An optically active proton-ionizable lariat crown ether derivative 2 was prepared. Host 2 displays enantiomeric selectivity toward phenylglycinol (K_large/K_small=3.2) and phenylalaninol (K_large/K_small=1.7). The key intermediate 1 was synthesized in two steps from commercially available binaphthol in 30% yield.

Full text of DOI:10.1016/S0040-4020(02)00074-1

TETRAHEDRON
Pergamon
Tetrahedron 58 )2002) 1679±1684
Synthesis of the proton-ionizable lariat crown ether and chiral
recognition of primary amines
Kazunori Tsubaki,a Hiroyuki Tanaka,a Takayoshi Kinoshitab and Kaoru Fujia,p
aInstitute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
bExploratory Research Laboratories, Fujisawa Pharmaceutical Co. Ltd, Tokodai, Tsukuba, Ibaragi 300-2698, Japan
Received 27 December 2001; accepted 21 January 2002
AbstractÐAn optically active proton-ionizable lariat crown ether derivative 2 was prepared. Host 2 displays enantiomeric selectivity
toward phenylglycinol )Klarge/Ksmallˆ3.2) and phenylalaninol )Klarge/Ksmallˆ1.7). The key intermediate 1 was synthesized in two steps from
commercially available binaphthol in 30% yield. q 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction
asymmetric synthesis.2 Furthermore, when substituted
onto chiral crown ethers, the 1,10-binapthyl moiety has
enabled the development of receptors capable of chiral
recognition.3,4 Among these receptors, several lariat
binaphthyl crown ethers have been reported,5 most with
lariat parts on the 3,30 positions.6 We expected that a host
molecule with lariat functionality on the crown ring,
especially in the opposite side of the 1,10-binaphthyl
group, could effectively discriminate chirality of guest
molecules. Following this model, a novel binaphthyl
crown ether 1 possessing a scaffolding hydroxy group in
the opposite direction of binaphthyl, has been synthesized.
One of advantages of this basic structure 1 includes
capabilities to serve as a starting material to a number of
tailor-made synthetic hosts by chemical transformations of
the hydroxy group. In this paper, we report the synthesis of a
host molecule 2 with nitrophenol as the lariat moiety,7 and
the synthesis of the intermediate binaphthyl crown alcohol
1. The degree of chiral recognition for primary amines will
additionally be discussed )Fig. 1).
Optically active 1,10-binaphthyl skeletons1 have been
widely used as highly effective catalysts in the ®eld of
O
O
O
OH
O
O
O
1
binding or
catalytic site
O
O
O
O
O
X
O
2. Results and discussion
O
O
Syntheses of the intermediate 1 and host molecule 2 were
carried out as outlined in Scheme 1. )S)-Binaphthol ).99%
ee) was reacted with 2-)2-chloroethoxy)-ethanol in the
presence of potassium carbonate and potassium iodide,
followed by cyclization with epichlorohydrin in the
presence of potassium tetra¯uoroborate as a template to
afford the binaphthyl crown alcohol 1 in 30% yield. As
suitable conditions for determining the enantiomeric excess
of 1 were not found, the binaphthyl crown alcohol was
converted to its acetate 3 in 97.0% ee. The binaphthyl
crown alcohol 1 )97.0% ee) was treated with TsCl to give
tosylate 4, and was then recrystallized twice from ethyl
acetate in 76% yield. The tosylate 4 was converted to
OH
O
O
O
O
O
NO2
2
Figure 1.
Keywords: crown ether; chiral recognition; 1,10-binaphthyl; amino alcohol.
Corresponding author. Tel.: 181-774-38-3190; fax: 181-774-38-3197;
e-mail: fuji@scl.kyoto-u.ac.jp
p
0040±4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020)02)00074-1

1680
K. Tsubaki et al. / Tetrahedron 58 12002) 1679±1684
O
O
(i), (ii)
30%
OH
OH
O
O
OR
O
O
(S)-binaphthol
1: R = H
(v)
(iii)
3: R = Ac
4: R = Ts
80% (2 steps)
(iv)
76%
OH
OMOM
OMOM
OHC
(vi), (vii)
75%
(viii)
HO
MsO
NO2
NO2
NO2
6
5
(ix), (x)
18%
1
2
Scheme 1. Conditions: )i) 2-)2-Chloroethoxy)ethanol, K2CO3, KI; )ii) epichlorohydrin, KOH, KBF4; )iii) TsCl, pyridine; )iv) AcOK; )v) NaOH; )vi) MOMCl;
)vii) NaBH4; )viii) MsCl; )ix) NaH, 6; )x) HCl.
optically pure binaphthyl crown alcohol 1 by nucleophilic
acetoxylation followed by hydrolysis in 80% overall yield
for two steps. 5-Nitrosalicylaldehyde was protected by the
MOM groupand reduced with sodium borohydride to give
the benzyl alcohol 5 in 75% yield. Treatment of 5 with
methanesulfonyl chloride8 gave the corresponding mesylate
6 which was reacted with binaphthyl crown alcohol 1 in the
presence of sodium hydride followed by deprotection of the
MOM groupunder acidic conditions to afford the host
molecule 2 in 18% yield. An X-ray crystallographic analysis
of 1 derived from )^)-binaphthol de®ned the structure
unequivocally )Fig. 2). X-Ray analysis revealed the dihedral
angle of the two naphthalene rings to be 1018.
Figure 2. Crystal structure of )^)-1. Hydrogen atoms are excluded for
clarity.
Initially, complexation between host molecule 2 and
Figure 3. Absorption spectra of host 2 in the presence of n-butylamine in
methanol/acetonitrileˆ1:9 at 258C. [2]ˆ5.0£1025 M, [n-butylamine]ˆ0±
Figure 4. Job plot of host 2 and n-butylamine in methanol/acetonitrileˆ1:9
at 258C.
1.9£1022 M.

K. Tsubaki et al. / Tetrahedron 58 12002) 1679±1684
1681
the shielding ®eld of the naphthyl rings of host 2. Further-
more, cross peaks between the crown methylene protons of
2 and a-methylene protons of n-butylamine, as well as the
crown methylene protons and benzylic methylene protons
of 2 were observed in the NOESY spectrum )Fig. 6). These
®ndings indicate that the ammonium ion, generated from an
acid±base reaction between a lariat nitrophenol of host 2
and free n-butylamine, is incorporated into the crown ring
through cation±dipole interaction with oxygen atoms of
host 2 and/or through cation±p interaction between the
two naphthyl rings of host 2.
Association constants between host molecule 2 and n-hexyl-
amine in various solvents at 258C were determined by UV±
visible titration and analyzed by the Rose±Drago
method.9,10h Solvent should play an important role in this
host±guest complexation as the host, the guest, and the
resulting complex will be stabilized to different degrees in
solvents of various polarities. In the case of this system,
acidity of the lariat nitrophenol should be affected by
polarity of the solvent, thus, the trigger for the acid±base
reaction between nitrophenol and n-hexylamine is
in¯uenced by the nature of solvent. Association constants
and lmax are summarized in Table 1. The association
constant varies with solvent from Kaˆ14 )THF) to
Ka.105 )DMSO). In addition, large solvatochroism was
also observed with a 44 nm change to lmax. With the excep-
tion of methanol, it was observed that shifts of lmax roughly
correlated to the ET)30) values.11
Figure 5. Partial 1H NMR )400 MHz) spectra of )a) n-butylamine p-nitro-
phenolate, )b) n-butylamine and )c) 1:1 mixture of host 2 and n-butylamine
in CDCl3 at 258C.
n-butylamine was investigated. The isosbestic point at
349 nm as well as a Job plot based on D absorbance at
413 nm indicated the formation of a 1:1 complex in
methanol/acetonitrileˆ1:9 solution )Figs. 3 and 4).
To understand the mode of complexation, NMR studies of 2
and n-butylamine were performed )Fig. 5). Normally, the
signals of n-butylamine p-nitrophenolate shift to a lower
magnetic ®eld compared to free n-butylamine due to a
decrease in the electron density of the nitrogen atom
)Fig. 5a). However, signals ascribed to n-butylamine in
the 1:1 complex were shifted to a higher magnetic ®eld
)Fig. 5c). This indicates that n-butylamine is located under
Since enantiomeric recognition of chiral compounds was
®rst reported by Cram and co-workers,3b,c various kinds of
host molecules have been synthesized. Some of them have
Figure 6. NOESY )400 MHz) spectrum of a 1:1 mixture of host 2 )2.2£1022 M) and n-butylamine )2.2£1022 M) in CDCl3 at 218C. Ha means the a protons of
n-butylamine, Hb and Hc mean the benzyl protons of the lariat part and those of crown ether part of host 2, respectively.

1682
K. Tsubaki et al. / Tetrahedron 58 12002) 1679±1684
Table 1. Association constants )Ka) and lmax of the complex of host 2 with
n-hexylamine
Entry
Solvent
Ka
l
max )nm)
1
2
3
4
5
THF
14^1
46^5
115^5
5290^30
.105
395
407
422
403
439
CHCl3
CH3CN
MeOH
DMSO
The association constants were determined by UV±visible titration at 258C
and analyzed by Rose±Drago method.9,10h
been reported to discriminate enantiomers by color
change.10 Hence, we checked the ability of the enantiomeric
recognition of host molecule 2 toward various types of
primary amines. The association constants )Ka) were deter-
mined by UV titration in a methanol/acetonitrileˆ1:9 mixed
solvent system at 258C. In each association experiment, a
1:1 binding stoichiometry has been assumed. This was
generally supported by observation of the isosbestic point
during titration. Table 2 shows the association constants and
the enantioselectivity ratio. The association constants were
generally moderate and enantioselectivity ratios were small.
Unambiguous chiral discrimination was found for phenyl-
glycinol )KR/KSˆ3.2) as shown in Fig. 7. Enantioselective
recognition was also observed for phenylalaninol
Figure 7. D absorbance at 413 nm vs. [amine]/[2] plot in methanol/aceto-
nitrileˆ1:9 at 258C.
)KS/KRˆ1.7), though the degree of selection was small.
The reverse selectivity is noteworthy but as yet unexplained.
3. Conclusions
Table 2. Association constants for the complexes of host 2 with various
amines
In the present study, optically active binaphthyl crown
alcohol 1 was synthesized in only two steps from commer-
cially available binaphthol in 30% yield. Introducing a
nitrophenol group as a lariat moiety onto the scaffolding
hydroxy group, the chromogenic host molecule 2 was easily
constructed. Host 2 can discriminate enantiomers of phenyl-
glycinol by color development. The parent crown alcohol 1
is a useful building block for chiral recognition as various
lariat units, which act as binding or catalytic sites, can be
introduced easily in reactions of a small number of steps.
Entry
1
Structure
Con®guration
Ka
Klarge/Ksmall
)R)
)S)
66.9^2.9 1.1
62.6^2.5
NH2
2
3
4
)R)
)S)
925.8^47.8 1.1
976.9^50.0
NH2
NH2
)R)
)S)
368.3^12.8 1.0
357.3^14.0
OH
4. Experimental
4.1. General
)R)
)S)
248.7^15.6 1.1
217.7^15.4
OH
NH2
Melting points are uncorrected. Nuclear magnetic resonance
)NMR) spectra were taken at 200 or 400 MHz in CDCl3
with chemical shifts being reported as d ppm from tetra-
methylsilane as an internal standard and couplings are
expressed in Hz. FT-IR and UV spectra were obtained on
a JASCO FT/IR-300 and Shimadzu-2200, respectively.
NH2
5
6
7
)R)
)S)
30.4^1.2 3.2
9.4^0.5
OH
)R)
)S)
86.7^2.1 1.7
148.6^8.6
OH
4.1.1. Binaphthyl crown alcohol (S)-1 (97.0% ee). A
mixture of )S)-binaphthol )20.0 g, 70 mmol), potassium
carbonate )48.0 g, 0.35 mol), potassium iodide )2.3 g,
NH2
OH
)1R,2S)
)1S,2R)
119.7^4.0 1.0
124.3^3.4
14 mmol)
and
2-)2-chloroethoxy)-ethanol
)29 ml,
0.28 mol) in DMF )350 ml) was stirred at 1008C over
night. The reaction mixture was poured into the mixed
solvent of ethyl acetate and water. The organic layer was
separated, washed successively with water )three times),
hydrochloric acid, and brine. After drying over sodium sul-
fate, the solvent was evaporated in vacuo. To the solution of
residue )33.6 g) in dioxane )1000 ml), potassium hydroxide
NH2
8
)1R,2S)
)1S,2R)
48.1^3.8 1.1
52.4^5.0
OH
NH2

K. Tsubaki et al. / Tetrahedron 58 12002) 1679±1684
1683
)23.0 g, 0.35 mol), potassium tetra¯uoroborate )9.7 g,
77 mmol) and epichlorohydrin )6.0 ml, 77 mmol) were
added and the reaction mixture was stirred at 808C over
night. The solvent was evaporated under reduced pressure
and the residue was partitioned between ethyl acetate and
hydrochloric acid. The organic layer was washed succes-
sively with water )twice) and brine, dried over potassium
carbonate, and evaporated. The residue was puri®ed by
column chromatography )SiO2, n-hexane/ethyl acetateˆ1:1
to ethyl acetate) to afford 1 as colorless viscous oil )10.9 g,
30% yield). Small amount of 1 was converted to the
corresponding acetate 3 to determine ee. The optical purity
of 3 was determined to be 97.0% ee by HPLC )Daicel
Chiralpak AD column, 1.0 ml min21, hexane/2-propa-
nolˆ90:10, tR 33.0 min for the )S)-isomer and 40.0 min
for the )R)-isomer).
1
as colorless viscous oil )1.86 g, 80% yield).
20
[a]D ˆ2135.1 )cˆ1.00, CHCl3); IR )KBr) 3435, 3055,
1610 cm21; H NMR )200 MHz, CDCl3) d 2.64 )brs, 1H),
1
3.0±3.7 )16H), 3.82 )m, 1H), 3.9±4.3 )4H), 7.1±7.5 )8H),
7.8±8.0 )4H); HRMS Calcd for C31H34O7: 518.2305. Found:
518.2291. Anal. Calcd for C31H34O7: C, 70.57; H, 6.69.
Found: C, 70.71; H, 6.65.
4.1.4. Benzyl alcohol 5. To a mixture of 5-nitrosalicylalde-
hyde )10.0 g, 60 mmol) and potassium carbonate )125 g,
0.9 mol) in DMF )200 ml), methoxymethyl chloride )70 g,
0.9 mol) was added dropwise under water-bath cooling. The
reaction mixture was stirred for 3 h at room temperature.
The reaction mixture was poured into the mixed solvent of
ethyl acetate and water. The organic layer was separated,
washed with brine )three times), dried over magnesium sul-
fate, and evaporated in vacuo to give a residue )21.5 g).
Sodium borohydride )11.0 g, 0.9 mol) was added portion-
wise to the residue )21.5 g) in methanol )200 ml) at 08C for
1.5 h. The reaction mixture was poured into the mixed
solvent of ethyl acetate and water. The organic layer was
separated, washed successively with hydrochloric acid and
brine )three times), dried over magnesium sulfate, and
evaporated in vacuo. The residue was puri®ed by column
chromatography )SiO2, n-hexane/ethyl acetateˆ1:1) to
afford 5 as a pale yellow solid )9.56 g, 75% yield), mp
4.1.2. Tosylate (S)-4. p-Toluenesulfonyl chloride )1.80 g,
9.54 mmol) was added portionwise to a solution of 1
)97% ee, 3.3 g, 6.36 mmol) in pyridine )30 ml) at 08C and
the reaction mixture was stirred over night. Additional
toluenesulfonyl chloride )0.36 g, 1.91 mmol) was added to
the solution and stirred for further 8 h. The reaction mixture
was poured into the mixed solvent of ethyl acetate and
hydrochloric acid. The organic layer was separated, washed
successively with water )twice), aqueous sodium hydrogen
carbonate, water, and brine, dried over sodium sulfate, and
evaporated in vacuo. The residue was recrystallized from
ethyl acetate )twice) to afford 4 as pale yellow crystals
77±788C; IR )KBr) 3365, 1612, 1512 cm21 1H NMR
;
)200 MHz, CDCl3) d 3.51 )s, 3H), 4.78 )s, 2H), 5.33 )s,
2H), 7.19 )d, Jˆ9.0 Hz, 1H), 8.16 )dd, Jˆ9.0 2.2 Hz, 1H),
8.31 )d, Jˆ2.2 Hz, 1H); HRMS Calcd for C9H11NO5:
213.0637. Found: 213.0639. Anal. Calcd for C9H11NO5: C,
50.57; H, 5.20; N, 6.57. Found: C, 50.74; H, 5.24; N, 6.42.
20
)3.27 g, 76% yield), mp121±123 8C; [a]D ˆ2106.1
1
)cˆ1.01, CHCl3); IR )KBr) 3055, 1620, 1508 cm21; H
NMR )200 MHz, CDCl3) d 2.42 )s, 3H), 3.1±3.6 )16H),
3.9±4.2 )4H), 4.61 )m, 1H), 7.1±7.5 )10H), 7.7±8.0 )6H);
HRMS Calcd for C38H40O9S: 672.2393. Found: 672.2364;
Anal. Calcd for C38H40O9S: C, 67.84; H, 5.99. Found: C,
67.66; H, 6.05. Small amount of 4 was converted to the
acetate 3 to determine its ee ).99% ee).
4.1.5. Host (S)-2. To a solution of 5 )3.49 g, 16.4 mmol) and
triethylamine )22.9 ml, 164 mmol) in dichloromethane
)85 ml) was added dropwise methanesulfonyl chloride
)3.8 ml, 49.2 mmol) at 08C. After stirring for 1 h, the
mixture was poured into the mixed solvent of diethyl ester
and water. The organic layer was separated, washed succes-
sively with water, hydrochloric acid, aqueous sodium
hydrogen carbonate, water )three times), and brine, dried
over magnesium sulfate, and evaporated in vacuo to give
crude mesylate 6,8 which was directly used for the next step
without further puri®cation. 1H NMR )200 MHz, CDCl3) d
3.10 )s, 3H), 3.52 )s, 3H), 3.3 )m, 4H), 7.26 )d, Jˆ9.2 Hz,
1H), 8.26 )dd, Jˆ9.2, 2.6 Hz, 1H), 8.32 )d, Jˆ2.6 Hz, 1H);
HRMS Calcd for C10H13NO7S: 291.0413. Found: 291.0423.
In another vessel, sodium hydride )60% in mineral oil,
0.27 g, 6.56 mmol) was added portionwise to a solution of
1 )1.70 g, 3.28 mmol) in DMF )30 ml) at 08C and the
mixture was stirred for 30 min. Crude mesylate 6 in DMF
)30 ml) was added dropwise to the mixture at 08C and the
mixture was stirred over night at room temperature followed
by warming to 508C for 1 h. The mixture was poured into
the mixed solvent of ethyl acetate and aqueous hydrochloric
acid. The organic layer was separated, washed successively
with water )three times) and brine, dried over sodium sul-
fate, and evaporated in vacuo. The residue was dissolved in
4 M hydrogen chloride in ethyl acetate )3.0 ml) and the
solution was stirred for 8 h. The reaction mixture was
evaporated in vacuo and the residue was puri®ed by column
chromatography )SiO2, n-hexane/ethyl acetateˆ1:1) to
afford 2 as pale yellow foam )0.394 g, 18% yield). For
4.1.3. Binaphthyl crown alcohol (S)-1 (.99% ee). A
mixture of 4 )3.0 g, 4.46 mmol) and potassium acetate
)4.4 g, 44.6 mmol) in DMF )50 ml) was stirred at 1008C
for 8 h. The reaction mixture was poured into the mixed
solvent of ethyl acetate and hydrochloric acid. The organic
layer was separated and washed with water )twice), brine
and then dried over sodium sulfate. Evaporation to dryness
in vacuo gave )S)-3 )3.0 g), which was directly used for the
next stepwithout further puri®cation. A small amount of
)S)-3 was subjected to further puri®cation by PTLC to
give analytical sample as colorless viscous oil ).99% ee).
20
[a]D ˆ2115.4 )cˆ0.51, CHCl3); IR )KBr) 2890, 1734,
1
1591 cm21; H NMR )200 MHz, CDCl3) d 2.08 )s, 3H),
3.2±3.7 )16H), 3.9±4.3 )4H), 5.03 )m, 1H), 7.1±7.5 )8H),
7.8±8.0 )4H); HRMS Calcd for C33H36O8: 560.2411. Found:
560.2407; Anal. Calcd for C33H36O8: C, 70.70; H, 6.47.
Found: C, 70.44; H, 6.74. The solution of crude )S)-3
)3.0 g) in THF )50 ml), methanol )25 ml) and 0.2 M sodium
hydroxide )20 ml) was stirred over night at room tempera-
ture. The reaction mixture was poured into the mixed
solvent of ethyl acetate and hydrochloric acid. The organic
layer was separated, washed successively with water )twice)
and brine, dried over sodium sulfate, and evaporated in
vacuo. The residue was puri®ed by column chromatography
)SiO2, n-hexane/ethyl acetateˆ1:1 to ethyl acetate) to afford

1684
K. Tsubaki et al. / Tetrahedron 58 12002) 1679±1684
5. Review on related proton-ionizable crown ethers:
)a) McDaniel, C. W.; Bradshaw, J. S.; Izatt, R. M. Hetero-
cycles 1990, 30, 665±706. Review on related lariat crown
ethers: )b) Gokel, G. W.; Schall, O. F. Comprehensive
Supramolecular Chemistry, Vol. 1; Pergamon: Oxford, 1996
pp 97±152.
determination of binding constants, 2 was further puri®ed by
19
preparative recycling HPLC )chloroform). [a]D ˆ2178.2
)cˆ1.00, CHCl3); IR )KBr): 3272 )br), 1621, 1338 cm21; 1H
NMR )CDCl3, 400 MHz): d 3.20±3.64 )16H), 3.76±3.80
)1H), 3.92±4.21 )4H), 4.38 )s, 2H), 6.92 )d, Jˆ9.0 Hz,
1H), 7.17±7.26 )4H), 7.30±7.35 )2H), 7.46 )dd, Jˆ12.1,
9.0 Hz, 2H), 7.85 )dd, Jˆ8.0, 4.6 Hz, 2H), 7.91 )t,
Jˆ9.0 Hz, 2H), 7.99 )d, Jˆ2.9 Hz, 1H), 8.11 )dd, Jˆ9.4,
3.0 Hz, 1H); HRMS Calcd for C38H39NO10: 669.2574.
Found: 669.2556. Anal. Calcd for C38 H39NO10´H2O: C,
66.36; H, 6.01; N, 2.04. Found: C, 66.34; H, 5.70; N, 2.03.
6. )a) Helgeson, R. C.; Koga, K.; Timko, J. M.; Cram, D. J.
J. Am. Chem. Soc. 1973, 95, 3021±3023. )b) Helgeson,
R. C.; Timko, J. M.; Cram, D. J. J. Am. Chem. Soc. 1973,
95, 3023±3025. )c) Cram, D. J.; Helgeson, R. C.; Koga, K.;
Kyba, E. P.; Madam, K.; Sousa, L. R.; Siegel, M. G.; Moreau,
P.; Gokel, G. W.; Timko, J. M.; Sogah, G. D. Y. J. Org. Chem.
1978, 43, 2758±2772. )d) Timko, J. M.; Helgeson, R. C.;
Cram, D. J. J. Am. Chem. Soc. 1978, 100, 2828±2834.
)e) Helgeson, R. C.; Weisman, G. R.; Toner, J. L.; Tarnowski,
T. L.; Chao, Y.; Mayer, J. M.; Cram, D. J. J. Am. Chem. Soc.
1979, 101, 4928±4941. )f) Hyun, M. H.; Han, S. C.; Lipshutz,
B. H.; Shin, Y.-J.; Welch, C. J. J. Chromatogr., A 2001, 910,
359±365.
4.1.6. X-Ray crystallographic analysis of (^)-1.
C31H34O7, Mˆ518.61, triclinic, aˆ11.719)1), bˆ
Ê
12.8204)8), and cˆ10.0773)7) A, aˆ92.135)6), bˆ
Ê 3
103.795)6), and gˆ66.940)5)8, Vˆ1350.2)2) A , space
group P-1 )#2), Zˆ2, Dcalcdˆ1.276 g cm23, m)Cu Ka)ˆ
7.33 cm21, l)Cu Ka)ˆ1.54178 A, Tˆ296 K, 4822 re¯ec-
Ê
tions measured, 4594 unique )Rintˆ0.023) which were
used in all calculations. R1ˆ0.093, Rwˆ0.075. Further
details of the crystal structural investigation are available
on request from the Director of the Cambridge Crystallo-
graphic Data Centre.
7. Recent examples of nitrophenol as the lariat functionality:
)a) Hu, K.; Bradshaw, J. S.; Pastushok, V. N.; Krakowiak,
K. E.; Dalley, N. K.; Zhang, X. X.; Izatt, R. M. J. Org.
Chem. 1998, 63, 4786±4791. )b) Su, N.; Bradshaw, J. S.;
Zhang, X. X.; Savage, P. B.; Krakowiak, K. E.; Izatt, R. M.
J. Org. Chem. 1999, 64, 3825±3829. )c) Kim, J. S.; Shon, O. J.;
Ko, J. W.; Cho, M. H.; Yu, I. Y.; Vicens, J. J. Org. Chem.
2000, 65, 2386±2392.
References
1. For a recent review of 1,10-binaphthyl dimers, oligomers, and
polymers; Pu, L. Chem. Rev. 1998, 98, 2405±2494.
2. Comprehensive Asymmetric Catalysis, Jacobsen, E. N., Pfalts,
A., Yamamoto, H., Eds.; Springer: Heidelberg, 1999.
3. Review on related chiral crown ethers: )a) Stoddart, C. F.
Topics in Stereochemistry; Wiley-Intersience: New York,
1988 pp 207±288. )b) Zhang, X. X.; Bradshaw, J. S.; Izatt,
R. M. Chem. Rev. 1997, 97, 3313±3361. )c) Kyba, E. P.;
Siegel, M. G.; Sousa, L. R.; Sagah, G. D. Y.; Cram, D. J.
J. Am. Chem. Soc. 1973, 95, 2691±2692. )d) Kyba, E. P.;
Koga, K.; Sousa, L. R.; Siegel, M. G.; Cram, D. J. J. Am.
Chem. Soc. 1973, 95, 2692±2693. )e) Manchand, A. P.;
Chong, H.-S.; Ganguly, B. Tetrahedron: Asymmetry 1999,
10, 4695±4700.
8. Caution! Some chemicals that are generated during this
reaction cause in¯ammation of the skin.
9. Rose, N. J.; Drago, R. S. J. Am. Chem. Soc. 1959, 81, 6138±
6145.
10. )a) Naemura, K.; Tobe, Y.; Kaneda, T. Coord. Chem. Rev.
1996, 148, 199±219. )b) Kaneda, T.; Hirose, K.; Misumi, K.
È
J. Am. Chem. Soc. 1989, 111, 742±743. )c) Vogtle, F.; Knops,
P. Angew. Chem., Int. Ed. Engl. 1991, 30, 958±960. )d) Kubo,
Y.; Maeda, S.; Tokita, S.; Kubo, M. Nature 1996, 382, 522±
524. )e) Kubo, Y. Synlett 1999, 161±174. )f) Hirose, K.;
Ogasahara, K.; Nishioka, K.; Tobe, Y.; Naemura, K.
J. Chem. Soc., Perkin Trans. 2 2000, 1984±1993. )g) Tsubaki,
K.; Nuruzzaman, M.; Kusumoto, T.; Hayashi, N.; Wang,
B.-G.; Fuji, K. Org. Lett. 2001, 3, 4071±4073. )h) Hirose,
K. J. Inclusion Phenom. 2001, 39, 193±209.
4. Examples of chiral crown ethers as chiral ligands for asym-
metric reactions: )a) Nagayama, S.; Kobayashi, S. J. Am.
Chem. Soc. 2000, 122, 11531±11532. )b) Kobayashi, S.;
Hamada, T.; Nagayama, S.; Manabe, K. Org. Lett. 2001, 3,
165±167.
11. Reichardt, C. Angew. Chem., Int. Ed. Engl. 1979, 18, 98±110.