Enantioselective fluorescent sensors for N-Boc-protected amino acid anions based on BINOL

Article abstract of DOI:10.1002/cjoc.201090150

The four novel derivatives of BINOL have been prepared and the structures of these compounds characterized by IR, MS, ¹H and ¹³C NMR spectroscopy and elemental analysis. The enantioselective recognition of these receptors has been st

Full text of DOI:10.1002/cjoc.201090150

FULL PAPER
Enantioselective Fluorescent Sensors for N-Boc-Protected
Amino Acid Anions Based on BINOL
Xu, Kuoxia,b(徐括喜)
Bu, Zhanweia(卜站伟)
Huang, Kejingc(黄克靖)
Zhao, Jinb(赵瑾)
Wang, Chaojie*,b(王超杰)
a College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004, China
b Key Lab of Natural Medicinal and Immunal Engineering, Henan University, Kaifeng, Henan 475004, China
c College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang, Henan 464000, China
The four novel derivatives of BINOL have been prepared and the structures of these compounds characterized
1
by IR, MS, H and 13C NMR spectroscopy and elemental analysis. The enantioselective recognition of these
1
receptors has been studied by fluorescence titration and H NMR spectroscopy. The receptors exhibited different
chiral recognition abilities towards N-Boc-protected amino acid anions and formed 1∶ 1 complexes between host
and guest. Receptors exhibit excellent enantioselective fluorescent recognition ability towards the amino acid de-
rivatives.
Keywords receptor, fluorescence, enantioselective recognition, anions
Introduction
reserved for the enzyme realm.10 The molecular recog-
nition of amino acids by synthetic receptor molecules
has been attracting much attention due to the frequent
use of the basic amino acids (e.g., Lys, Arg, His and Ala)
for biological processes and therapeutic drugs made
from chiral amino acids intermediates.11 Herein, we de-
scribe the development of 1,1'-bi-2-naphthol (BINOL)
derivatives bearing amino acid units (Scheme 1), and
their bonding properties with N-Boc-protected amino
acid derivatives have been examined by using fluores-
cence titration experiments in CHCl3. Receptors exhib-
ited good enantioselective recognition abilities towards
chiral materials and formed 1∶ 1 complex with the
Chiral recognition of racemic compounds exists ex-
tensively in nature. It is of particular significance for
understanding the interactions of biological molecules
and for the designing of asymmetric catalysis systems.1
With the increasingly successful application to smart
artificial systems, chiral recognition which is a broader
and more commonly used ‘tool’ for academic research
and industry2 has gained greater scientific maturity.
The crucial points in the molecular design of
chemosensors are how to achieve the specific recog-
nition of a certain molecule and how to transduce the
recognition event into a signal.3 Many efforts involve
the covalent linking of an optical signaling unit (a
chromophore or a fluorophore) to a specific receptor for
the chiral molecule.4 Compared with other detection
methods, such as capillary electrophoresis,5 HPLC,6
absorption spectrometry,7 and electrochemistry,8 fluo-
rescence techniques have often been used to study the
interaction between enantiomers and receptors because
of their sensitivity, selectivity, and versatility.9
1
guests in CHCl3. H NMR experiments suggested that
hydrogen-bonding interaction between the host and
guest was the main factor in the recognition process.
Results and discussion
Synthesis
The synthesis of receptors S-1a, S-1b and R-1a,
R-1b is outlined in Scheme 1. The starting materials
binaphthyl dialdehydes were prepared from 1,1'-bi-2-
naphthol (BINOL).12 N-Boc-protected amino acid
methyl ester (2) was synthesized according to the lit-
erature with high yield,13 and then reacted with excess
amount of diamine to obtain the compounds 3. To avoid
the partial racemization of 3 in this reaction, the mate-
rial 2 and diamine were solved in large amount of
The binaphthyl unit was especially eyecatching for
its stable chiral configuration and tunable dihedral angle
between the two naphthalene rings. Over the last two
decades, the binaphthyl derivatives have been shown to
exhibit excellent enantioselectivities and turnovers in
several types of asymmetric reactions, often matching
the enantioselectivities traditionally regarded as being
*
E-mail: wcjsxq@henu.edu.cn; Tel.: 0086-0378-3881589; Fax: 0086-0378-3881589
Received September 22, 2009; revised November 28, 2009; accepted December 28, 2009.
Project supported by the National Natural Science Foundation of China (Nos. 20872027/B0206, 20805040) and the Educatiion Department of Henan
Province of China (No. 2010B15004).
Chin. J. Chem. 2010, 28, 803— 810
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Xu et al.
FULL PAPER
Scheme 1 Synthesis of the receptors S-1, R-1
methanol and continued to stir at room temperature,
especially at the end of reaction, the solvent and dia-
mine should be evaporated under high vacuum at about
30—40 ℃, because a little higher temperature may lead
the racemization of compound. Condensation of S- or
R-binaphthyl dialdehydes with compounds 3 followed
by reduction afforded the disubstituted BINOL S-1a or
S-1b (Scheme 1), respectively. In order to study how the
BINOL and amino acid units in S-1a or S-1b influenced
the enantioselective fluorescent recognition, the R-1a or
R-1b, diastereoisomeric compounds of S-1a or S-1b,
were also prepared. They are all readily soluble in
common organic solvents such as CHCl3, CH2Cl2,
CH3OH, DMSO, and DMF. The structures of all these
Scheme 2 Structures of the guests
omers, L-, D-Ala, and Phe anions. Because there was
almost no change observed on the UV-vis spectra of
receptors upon addition of L- or D-Ala or Phe anions,
the interaction between host and anion was only evalu-
ated by fluorescent spectra.
Upon addition of L- or D-Ala or Phe anions, the dif-
ferent fluorescent quenching degree of S-1a was ob-
served. The quenching efficiency of L-amino acid ani-
ons was much higher than the D-amino acid anions.
Figures 1 and 2 show the fluorescence emission spectra
of a mixture of S-1a and different concentrations of the
1
compounds were characterized by IR, MS, H and 13C
NMR spectroscopy and elemental analysis.
Fluorescence spectra study
The properties of the chiral recognition of receptors
S-1a and S-1b were investigated in the absence and
presence of S- and R-N-Boc-protected alanine anion
(Ala) and N-Boc-protected phenylalanine anion (Phe),
whose amino groups were protected by the tert-butyl-
oxycarbonyl functionality. In each case tetrabutylam-
monium was used as the counter cation, which could
increase the reaction between the receptor and guest by
hydrogen bondings. We also chose two amino alcohols,
namely alaninol and phenylalaninol, as guests to com-
pare the association abilities of the hosts to bind with
neutral molecules (Scheme 2).
L- or D-Ala anion in CHCl3 (λ ＝278 nm), respectively.
ex
The graphs in the top right corner of Figure 1 and Fig-
ure 2 illustrate the fluorescence intensity change of re-
ceptor S-1a upon addition of L- and D-Ala anions, re-
spectively. Figure 3 shows the different fluorescence
intensity changes when the same equiv. of L- or D-Ala
anion was added to the host S-1a. The quenching effi-
ciency was 70% when 20 equiv. of L-Ala anion was
added to the solution of S-1a, while the quenching effi-
ciency was only 30% when 20 equiv. of D-Ala anion
was added. The quenched efficiencies (∆IS/∆IR＝2.33)
indicated that the host S-1a has a good enantioselective
The fluorescence spectra were recorded from a solu-
tion of receptor S-1a or S-1b (1.25×10－ mol/L) in
5
CHCl3 in the absence or presence of various enanti-
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Chin. J. Chem. 2010, 28, 803— 810

Enantioselective Fluorescent Sensors for Amino Acid Anions
Figure 1 Fluorescence spectra of receptor S-1a (1.25× 10－
Figure 3 Fluorescence spectra of host S-1a (1.25× 10－ 5 mol/L)
with 20 equiv. of L- and D-Ala anion in CHCl3.
5
mol/L) with L-Ala anion in CHCl3. The anion equivalents are 0, 2,
4, 6, 8, 10, 20, 40, 60, 80, 100, 200, 300, 400 and 500, λ ＝ 278
ex
nm. Inset: changes in the fluorescence intensity of S-1a at 371 nm
upon addition of L-Ala anion. The line shown is a line-fitted
curve. The correlation coefficient (R) of the nonlinear curve fit-
ting is 0.9972.
X
X
(X
X )/2C {C
C
1/K
[(C
H
＝
＋
－
＋
＋
－
＋
0
lim
0
0
H
G
ass
CG 1/K )2 4C C ]1/2}
(1)
＋
－
ass
H
G
The association constants for the interaction of S-1a
with the L- and D-Ala anion are (2.99±0.21)×104 and
(3.34±0.19)×103 L/mol, respectively. Compound S-1a
gives an enantioselectivity Kass(S-Ala)/Kass(R-Ala) ＝ 8.95.
The dramatically different fluorescent responses and
quenching efficiencies observed for the two enantiomers
indicate that S-1a has excellent enantioselective fluo-
rescent recognition ability towards the Ala anion. Simi-
lar phenomena were observed when L- or D-Phe anions
were added into a solution of S-1a. The result of a
non-linear curve fitting (at 371 nm) indicates that a 1∶
1 complex was formed between receptor S-1a and L- or
D-Phe (see the Table 1). In addition, the association
constants (Kass) were different (see the Table 1)
[Kass(S)＝(3.17±0.11)×104 L/mol, ∆G0＝－25.69 kJ/
mol; Kass(R)＝(3.09±0.08)×103 L/mol, ∆G0＝－19.92
kJ/mol], yielding an S/R selectivity [Kass(S)/Kass(R)] of
10.26 for the Phe anions and a ∆∆G0 value of －5.77
kJ/mol, demonstrating that S-1a has good chiral recog-
nition ability towards the enantiomers of Phe anions.
The binding of S-1a with alaninol or phenylalaninol
is also listed in Table 1. Upon the addition of alaninol or
phenylalaninol into a solution of S-1a in CHCl3, the
fluorescence intensity of S-1a was slightly quenched by
both L- and D-enantiomers (see Table 1). This indicates
that hydrogen bonding plays an important role in the
interaction between the host and guest and leads to the
easier signal transductions of chiral recognition by
fluorescence method.
Figure 2 Fluorescence spectra of receptor S-1a (1.25× 10－
5
mol/L) with D-Ala anion in CHCl3. The anion equivalents are 0,
2, 4, 6, 8, 10, 20, 40, 60, 80, 100, 200, 300, 400 and 500, λ ＝
ex
278 nm. Inset: changes in the fluorescence intensity of S-1a at
371 nm upon addition of D-Ala anion. The line shown is a
line-fitted curve. The correlation coefficient (R) of the nonlinear
curve fitting is 0.9980.
recognition ability between the L- and D-Ala anions,
respectively. Satisfactory nonlinear curve fitting (the
correlation coefficient is over 0.99) confirmed that S-1a
and the L- or D-Ala formed a 1∶1 complex (see the
insets of Figure 1 and Figure 2). For a complex of 1∶1
stoichiometry, the association constant (Kass) can be
calculated by using Eq. (1) from the Origin 7.0 software
package,14,15 where X represents the fluorescence inten-
sity, respectively, CH and CG are the host and guest con-
centrations, and C0 is the initial concentration of the
host. The association constants (Kass) and correlation
coefficients (R) obtained by a nonlinear least squares
analysis of X versus CH and CG are listed in Table 1.
Similar phenomena were observed when L- or D-Ala
and Phe anions were added into a solution (1.25×10－
5
mol/L) of S-1b. The emission spectra of S-1b appeared
at 371 nm when it was excited at 278 nm. The
quenching efficiencies of receptor S-1b were 62% and
57% by 20 equiv. of L-Ala and L-Phe anions while 37%
and 31% by D-Ala and D-Phe anions in CHCl3, respec-
tively. Enantioselective fluorescence responses were
observed, which gave ∆IS/∆IR＝1.68 for Ala anions and
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Xu et al.
FULL PAPER
Table 1 Association constants (Kass), correlation coefficients (R), enantioselectivities (Kass(S)/Kass(R)), Gibbs free energy changes (－∆G0),
and ∆∆G0 calculated from ∆G0 for the complexation of receptors S-1 and R-1 with L-/D-guests in CHCl3 at 25 ℃
－
－
－
1
1
1
Entry
1
Host
S-1a
Guest
L-Alac
Kassa,b/(L•mol )
(2.99±0.21)×104
(3.34±0.19)×103
(3.17±0.11)×104
(3.09±0.08)×103
(6.72±0.31)×102
(4.31±0.05)×102
(5.98±0.21)×102
(1.99±0.15)×102
(3.07±0.27)×104
(3.16±0.19)×103
(3.04±0.27)×104
(3.09±0.08)×103
(5.60±0.31)×102
(1.11±0.05)×102
(5.81±0.21)×102
(1.91±0.15)×102
(3.26±0.22)×103
(3.02±0.13)×104
(3.47±0.26)×103
(3.29±0.24)×104
(3.51±0.14)×102
(6.94±0.29)×102
(1.51±0.07)×102
(8.81±0.44)×102
(2.88±0.09)×103
(2.69±0.11)×104
(2.41±0.13)×103
(2.08±0.15)×104
(1.35±0.11)×102
(7.03±0.27)×102
(2.84±0.09)×102
(8.29±0.32)×102
R
Kass(S)/Kass(R) －∆G0/(kJ•mol ) ∆∆G0/(kJ•mol )
0.9972
0.9980
0.9927
0.9928
0.9924
0.9902
0.9944
0.9919
0.9971
0.9984
0.9947
0.9974
0.9954
0.9919
0.9928
0.9913
0.9903
0.9912
0.9941
0.9937
0.9917
0.9951
0.9903
0.9927
0.9972
0.9961
0.9935
0.9922
0.9942
0.9929
0.9918
0.9909
25.55
2
S-1a
S-1a
S-1a
S-1a
S-1a
S-1a
S-1a
S-1b
S-1b
S-1b
S-1b
S-1b
S-1b
S-1b
S-1b
S-1a
S-1a
S-1a
S-1a
S-1a
S-1a
S-1a
S-1a
S-1b
S-1b
S-1b
S-1b
S-1b
S-1b
S-1b
S-1b
D-Alac
L-Phec
D-Phec
8.95
10.26
1.56
20.12
25.69
19.92
16.14
15.04
15.85
13.12
25.62
19.98
25.59
19.92
15.69
11.68
15.78
13.02
20.06
25.57
20.21
25.79
14.53
16.22
12.44
16.81
19.75
25.29
19.31
24.65
12.16
16.25
14.01
16.66
－5.43
－5.77
－1.1
－2.73
－5.64
－5.67
－4.01
－2.76
5.51
3
4
5
L-Alaninol
D-Alaninol
L-Phenylalaninol
D-Phenylalaninol
L-Alac
D-Alac
L-Phec
6
7
8
3.01
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
9.72
D-Phec
9.84
L-Alaninol
D-Alaninol
L-Phenylalaninol
D-Phenylalaninol
L-Alac
D-Alac
L-Phec
5.05
3.04
1/9.26
1/9.48
1/1.98
1/5.64
1/9.34
1/8.63
1/5.21
1/2.92
D-Phec
5.58
L-Alaninol
D-Alaninol
L-Phenylalaninol
D-Phenylalaninol
L-Alac
D-Alac
L-Phec
1.69
4.37
5.54
D-Phec
5.34
L-Alaninol
D-Alaninol
L-Phenylalaninol
D-Phenylalaninol
4.09
2.65
a The data were calculated from results of fluorescence titrations in CHCl3. b All error values were obtained from nonlinear curve fitting.
c Ala and Phe tetrabutylammonium salts, the amino group was protected by a tert-butyloxycarbonyl function.
∆IS/∆IR＝1.84 for Phe anions.
tor upon addition of the anion is similar to the anon-
induced fluorescence decrease reported previously.17
Due to the similar structure of S-1a and S-1b, the fluo-
rescent variations of S-1a, S-1b showed the same trend.
Since there were no changes in the UV-vis spectra of
receptors when treated with L- or D-anions, a photoin
electron-transfer (PET) process might be responsible for
the fluorescent quenching.18 In the presence of guest
anions, the fluorescence quenching of receptors S-1a,
S-1b most likely arose from the change of the free en-
ergy (∆GPET) of the electron transfer between the ex-
cited fluorophore and the receptor units (NH).19 When
the guest anions interacted with receptors S-1a or S-1b,
the reductive potential of the receptor units increased
The continuous variation methods were also em-
ployed to determine the stoichiometric ratio of the re-
ceptor S-1a with guests [L- and D-Ala anions]. The total
concentration of host and guest was constant (1.0×10－
6
mol/L) in CHCl3, with a continuously variable molar
fraction of host ([H]/([H]＋[G])). Figure 4 shows the
Job’s plots of receptor S-1a with L- and D-Ala anion (at
371 nm, λ ＝278 nm). When the molar fraction of the
ex
host was 0.50, the fluorescence intensity reached a
maximum, which demonstrated that receptor S-1a
formed a 1∶1 complex with L- and D-Ala anions, re-
spectively.16
The decrease in fluorescence intensity of the recep-
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Chin. J. Chem. 2010, 28, 803— 810

Enantioselective Fluorescent Sensors for Amino Acid Anions
NMR in CDCl3 as chiral solvating agents at room tem-
perature. The spectra of receptor S-1a and its complex
with equimolar amounts of racemic Ala anions are
shown in Figure 5. When treated with equimolar
amounts of receptor S-1a, the signal of the CH proton of
the racemic Ala anion splitted into a more complicated
signal pattern (Figure 5C) with a downfield shift. The
interaction of receptor S-1a with L-enantiomer shows
that the CH proton has a larger downfield shift (from
δ 3.85 to 4.27, ∆δ＝0.42, Figure 5D) than the CH pro-
ton of D-enantiomer (from δ 3.85 to 4.19, ∆δ＝0.34,
Figure 5E). Moreover, the signals of the OH proton in
the 1H NMR spectra of receptor S-1a have an downfield
shift from δ 6.57 to 6.78 (∆δ＝0.21, Figure 5D) or 6.74
(∆δ＝0.17, Figure 5E) for L- or D-Ala anion, respec-
tively, while the signals of the peaks of binaphthyl
fragments are downfield shifted and broadened with the
addition of the guest. The above results indicate that
S-1a has a stronger interaction with the L-Ala anion
than with its D-enantiomer. This indicated that the in-
teraction between the host and guest also happened by
multiple hydrogen bondings. The above results illustrate
that the nature of the receptor, multiple hydro-
Figure 4 Job’s plots of receptor S-1a with L- and D-Ala anions
(371 nm, λex＝278 nm). The total concentration of the host ([H])
and guest ([G]) is 1.0×10－ mol/L in CHCl3. I0: fluorescence
6
intensity of S-1a; I: fluorescence intensity of S-1a in the presence
of the guest.
along with the ratio of the electron transfer from the
HOMO orbit of receptor units to the excited binaphthyl
group, which in turn led to a more facile intramolecular
PET process.20 Therefore fluorescence quenching was
observed.
gen-bonding
interactions,
and
complementary
chiral-centre interactions maybe responsible for the en-
antiomeric recognition of amino acid anion.22
In order to study how the chirality of the amino acid
unit and BINOL groups in S-1a or S-1b influenced the
enantioselective fluorescent recognition, R-1a and R-1b,
the diastereoisomeric compounds of S-1a and S-1b,
were also prepared, and their interactions with Ala, Phe
anions, alaninol and phenylalaninol studied were which
showed the opposite enantioselectivity (see the Table 1).
That is, the enantiomer of D-guest, quenched the fluo-
rescence of D- more efficiently than L-guest. The result
of fluorescence titration indicated a matched chirality
between the guest anions center and the chiral BINOL
unit led to the enantioselective recognition. The enan-
tiomers of guest anions interacted with R-1a, R-1b and
S-1a, S-1b in a same fashion.
Table 1 indicates that the interaction of S-1a or S-1b
with the L-Ala and L-Phe anions is better than that with
the D-Ala and D-Phe anions, which is probably due to
the L-amino acid anions having a more complementary
structure with receptors S-1a or S-1b.
The receptors S-1a or S-1b and R-1a or R-1b all ex-
hibit good chiral recognition ability towards the enan-
tiomers of the Ala and Phe anions, which indicates that
the preorganized structure of the chiral center of
binaphthyl unit plays important roles in the enantiose-
lective recognition process.
Conclusion
In summary, four chiral fluorescent receptors S-1a,
S-1b and R-1a, R-1b were synthesized and their enanti-
oselective recognition was studied by fluorescence titra-
1
tion and H NMR spectroscopy. All receptors exhibit
different
chiral
recognition
abilities
towards
N-Boc-protected amino acid anions and form 1∶1
complexes with the guest molecules. It is clear that na-
ture of the receptor, good structural preorganization,
multiple hydrogen-bonding interactions and comple-
mentary chiral-centre interactions induce may be re-
sponsible for the enantiomeric recognition of anionic
guests.22 All receptors are promising in their use as
fluorescence sensors for N-Boc-protected amino acid
anions. The remarkably different fluorescent responses
that result from complexation reveal that S-1a, S-1b and
R-1a, R-1b could be used as fluorescent chemosensors
for the N-Boc-protected alanine anion or N-Boc-pro-
tected phenylalanine anion (Phe) in the future.
Experimental
General
1H NMR study
The reagents used were of commercial origin and
were employed without further purification. Purifica-
tions by column chromatography were carried out over
silica gel (230—400 mesh). The IR spectra were per-
1H NMR experiments were undertaken to assess the
chiral recognition properties between receptor S-1a and
chiral anionic guest because NMR spectroscopy can
provide structural and dynamic information directly.21
Chiral recognition studies were carried out with a 400
1
formed on a Nicolet 670 FT-IR spectrophotometer. H
NMR and 13C NMR spectra were recorded on a Bruker
AV-400 spectrometer. Mass spectra were determined by
1
MHz NMR spectrometer using receptor S-1a by H
Chin. J. Chem. 2010, 28, 803— 810
© 2010 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Xu et al.
FULL PAPER
－
3
Figure 5 1H NMR spectra of S-1a and its guest complexes at 25 ℃ ([S-1a]＝[guest]＝4.0×10 mol/L) in CDCl3 at 400 MHz. (A)
Racemic Ala anion; (B) receptor S-1a; (C) receptor S-1a＋racemic Ala anion; (D) receptor S-1a＋L-Ala anion; (E) receptor S-1a＋D-Ala
anion.
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Chin. J. Chem. 2010, 28, 803— 810

Enantioselective Fluorescent Sensors for Amino Acid Anions
ESI recorded on a Esquire 3000 LC-MS mass instru-
ment. Optical rotations were taken on a Perkin-Elmer
Model 341 polarimeter. Fluorescence spectra were ob-
tained with a F-7000 FL Spectrophotometer. Elementa-
lanalyses were performed by the Vario Elemental
CHSN-O microanalyzer. All other commercially avail-
able reagents were used without further purification.
The anions were used as their tetrabutylammonium salts.
The N-protected (by the tert-butyloxycarbonyl func-
tionality) amino acid derivatives were synthesized ac-
cording to a literature method.13
and extracted with CHCl3 for three times. The organic
layers were combined and dried over anhydrous Na2SO4.
After filtration, the solvent was evaporated under re-
duced pressure and the residue was purified by column
chromatography on a silica gel [eluent: V(CHCl3)∶
V(CH3CH2OH)＝50∶1]. The pure product was ob-
tained as a pale yellow solid.
S-1a: Yield 72.4%; [α]2D0 －31.95 (c 0.05, CHCl3).
1
R-1a: Yield 78.2%; [α]2D0 ＋33.41 (c 0.05, CHCl3). H
NMR (CDCl3) δ: 1.36 (s, 18H, CH3), 2.36 (s, 2H, NH),
2.64—2.73 (m, 4H, CH2), 2.92—3.01 (m, 4H, CH2),
3.16—3.26 (m, 4H, PhCH2), 4.14 (d, J＝8.0 Hz, 4H,
Ar-CH2), 4.72—4.81 (m, 2H, CHCH2), 6.57 (s, 2H,
OH), 7.04—7.07 (m, 2H, ArH), 7.16—7.33 (m, 10H,
pH), 7.57 (d, J＝7.2 Hz, 2H, ArH), 7.64 (d, J＝2.7 Hz,
2H, NH-Boc), 7.81 (d, J＝8.1 Hz, 2H, ArH), 7.86 (d,
J＝7.2 Hz, 2H, ArH), 7.88 (d, J＝8.0 Hz, 2H, ArH),
7.91 (s, 2H, CONH); 13C NMR (CDCl3) δ: 25.35, 39.42,
39.97, 45.51, 47.64, 49.89, 57.12, 57.37, 70.53, 71.80,
124.96, 125.24, 125.64, 125.86, 127.14, 127.17, 128.37,
129.94, 130.14, 130.51, 130.94, 131.29, 132.79, 132.91,
133.76, 133.96, 134.30, 152.53, 153.55, 173.31; IR
(KBr) ν: 3417, 3099, 2954, 1682, 1537, 1＋263, 1231, 751
General procedure for the synthesis of compounds
3a and 3b
Under nitrogen, excess diamine (10 mmol) in 10 mL
of CH3OH was added dropwise into a solution (20 mL)
of compound S-tert-butoxycarbonylamino-propionic
acid methyl ester 2 (2 mmol) in CHCl3/CH3OH (1∶10,
V∶V) under an ice-bath. After the addition, the mixture
was stirred at room temperature for 48 h. After evapora-
tion of the solvent and the residual diamine under re-
duced pressure, CHCl3 (30 mL) were added and washed
with H2O (30 mL×3), then the organic layer was sepa-
rated and dried over Na2SO4. After filtration, the solvent
was removed under reduced pressure to give 3a or 3b as
colorless ropy oil.
－1
cm ; ESI-MS m/z (%): 947 (M＋Na , 100). Anal.
calcd for C54H64N6O8: C 70.11, H 6.97, N 9.08; S-1a:
found C 70.02, H 7.00, N 9.03; R-1a: found C 69.98, H
7.01, N 9.01.
3a: Yield 92% (0.57 g); [α]2D0 ＋23.61 (c 0.05,
CHCl3); 1H NMR (CDCl3) δ: 1.49 (s, 9H, CH3), 1.75 (s,
2H, NH2), 2.88 (t, J＝8.0 Hz, 2H, CH2), 3.09 (t, J＝8.0
Hz, 2H, CH2), 3.39 (d, J＝6.4 Hz, 2H, CH2), 4.29 (t,
J＝6.7 Hz, 1H, CH), 6.03 (s, 1H, NHBoc), 7.33—7.07
(m, 5H, Ph), 7.65 (s, 1 H, CONH); 13C NMR (CDCl3) δ:
27.9, 28.8, 37.2, 41.2, 44.3, 57.8, 79.4, 125.9, 127.1,
128.3, 139.8, 156.8, 174.4; ESI-MS m/z (%): 308 (M＋
＋1, 100). Anal. calcd for C16H25N3O3: C 62.52, H 8.20,
N 13.6; found C 62.39, H 8.31, N 13.51.
S-1b: Yield 72.4%; [α]2D0 －30.07 (c 0.05, CHCl3).
1
R-1b: Yield 78.2%; [α]2D0 ＋32.85 (c 0.05, CHCl3). H
NMR (CDCl3) δ: 1.39 (s, 18H, CH3), 2.38 (s, 2H, NH),
2.56—2.75 (m, 8H, CH2), 2.94—3.03 (m, 4H, CH2),
3.18—3.26 (m, 4H, PhCH2), 4.16 (d, J＝8.0 Hz, 4H,
Ar-CH2), 4.84—4.76 (m, 2H, CHCH2), 6.58 (s, 2H,
OH), 7.06—7.09 (m, 2H, ArH), 7.16—7.34 (m, 10H,
Ph), 7.59 (d, J＝7.2 Hz, 2H, ArH), 7.66 (d, J＝2.7 Hz,
2H, NH-Boc), 7.83 (d, J＝8.1 Hz, 2H, ArH), 7.89 (d,
J＝7.2 Hz, 2H, ArH), 7.90 (d, J＝8.0 Hz, 2H, ArH),
7.95 (s, 2H, CONH); 13C NMR (CDCl3) δ: 25.37, 39.42,
41.72, 44.18, 45.50, 47.62, 49.91, 57.11, 57.31, 70.51,
71.87, 124.99, 125.36, 125.67, 125.89, 127.14, 127.23,
128.37, 129.97, 130.33, 130.92, 131.43, 131.35, 132.85,
132.99, 134.17, 134.39, 134.78, 152.83, 154.37, 174.82;
IR (KB－r) ν: 3414, 3102, 2951, 1680, 1539, 1263, 1231,
3b: Yield 95% (0.61 g); [α]2D0 ＋21.06 (c 0.05,
CHCl3); 1H NMR (CDCl3) δ: 1.47 (s, 9H, CH3), 1.72 (s,
2 H, NH2), 2.92—3.07 (m, 6H, CH2), 3.37 (t, J＝6.7 Hz,
2H, CH2), 4.32 (t, J＝6.9 Hz, 1H, CH), 6.08 (s, 1H,
NHBoc), 7.09—7.35 (m, 5H, Ph), 7.63 (s, 1H, CONH);
13C NMR (CDCl3) δ: 27.9, 28.8, 32.7, 37.9, 43.6, 47.8,
58.2, 79.9, 126.3, 127.4, 128.7, 139.6, 156.9, 174.7;
ESI-MS m/z (%): 322 (M＋＋1, 100). Anal. calcd for
C17H27N3O3: C 63.53, H 8.47, N 13.07; found C 63.42,
H 8.52, N 12.98.
＋
1
750 cm ; ESI-MS m/z (%): 975 (M＋Na , 100). Anal.
calcd for C56H68N6O8: C 70.56; H 7.19; N 8.82; S-1b:
found C 70.22, H 7.13, N 8.91; R-1b: found C 70.31, H
7.11, N 8.93.
General procedure for the synthesis of compound
R-1a, R-1b, S-1a and S-1b
Preparation of samples for fluorescence measure-
ment
A mixture of the R- or S-binaphthyl dialdehyde (0.34
g, 1 mmol) and compound 3a or 3b (2.2 mmol) in dry
CHCl3 (30 mL) was stirred for 48 h under N2 at room
temperature until TLC showed the disappearance of the
starting material. NaBH4 (0.19 g, 5 mmol) was then
added to the mixture in three portions over 3 h, after
which it was stirred under nitrogen for another 6 h at 50
℃. The mixture was poured into 30 mL of 10% Na-
HCO3 after removing the solvent under reduced pressure,
All solutions were prepared using volumetric sy-
ringes, pipettes, and volumetric flasks. The tetrabu-
tylammonium salts were prepared by adding 1 equiv. of
tetrabutylammonium hydroxide in methanol to a solu-
tion of the corresponding carboxylic acid in methanol
and stock solutions of the salts were prepared in CHCl3.
The resulting syrup was dried under high vacuum for 24
h, analyzed by NMR spectroscopy, and stored in a des-
Chin. J. Chem. 2010, 28, 803— 810
© 2010 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
809

Xu et al.
FULL PAPER
10 (a) Li, Z. B.; Lin, J.; Pu, L. Angew. Chem., Int. Ed. 2005, 44,
1690.
iccator. The compounds S-1a, S-1b and R-1a, R-1b
were prepared as stock solutions in CHCl3. The test so-
lutions were prepared by adding different volumes of
anion solution to a series of test tubes and then the same
amount of stock solution of the host compound was
added to each of the test tubes and diluted to 3.0 mL
with CHCl3. After being shaken for several minutes, the
test solutions were analyzed immediately.
(b) Trupp, S.; Schweitzer, A.; Mohr, G. J. Org. Biomol.
Chem. 2006, 4, 2965.
(c) Xu, K. X.; Qiu, Z.; Zhao J. J.; Zhao, J.; Wang, C. J.
Teteahedron: Asymmetry 2009, 20, 1690.
(d) Xu, K. X.; Cheng, P. F.; Wang, Y. X.; Zhao, J.; Wang, C.
J. Supramol. Chem. 2009, 21, 618.
11 (a). Zhang, X. X.; Bradshaw, J. S.; Izatt, R. M. Chem. Rev.
1997, 97, 3313.
Job’s plots
(b) Kim, K. S.; Kim, B. H.; Park, W. M.; Cho, S. J. J. Am.
Chem. Soc. 1993, 115, 7472.
(c) Famulok, M.; Szostak, J. W. J. Am. Chem. Soc. 1992,
114, 3990.
Stock solutions of host S-1a and the L-Ala, D-Ala
tetrabutylammonium salts in CHCl3 system (the total
－6
concentration of the host and guest is 1.0×10 mol/L)
were freshly prepared. The receptor and Ala solutions
were added to the test tubes in ratios of 9∶1, 8∶2 to
0∶10, respectively. After being shaken for several
minutes, the work solution could be measured immedi-
ately.
12 (a) Zhang, H. C.; Huang, W. S.; Pu, L. J. Org. Chem. 2001,
66, 481.
(b) Stock, H. T.; Kellogg, R. M. J. Org. Chem. 1996, 61,
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13 (a) Krapcho, A. P.; Kuell, C. S. Synth. Commun. 1990, 20,
2559.
(b) Du, C. P.; You, J. S.; Yu, X. Q.; Liu, C. L.; Lan, J. B.;
Xie, R. G. Tetrahedron: Asymmetry 2003, 14, 3651.
14 (a) Valeur, B.; Pouget, J.; Bourson, J. J. Phys. Chem. 1992,
96, 6545.
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810
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© 2010 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2010, 28, 803— 810