Synthesis of polymers bearing proline moieties in the side chains and their application as catalysts for asymmetric induction

Article abstract of DOI:10.1002/pola.24813

Novel polyphenylacetylene and polystyrene derivatives carrying L-proline moieties at the side chains were synthesized by the rhodium-catalyzed and radical polymerizations of the corresponding monomers. The polyphenylacetylene derivatives showed Cotton effects at the absorption region of the main chain, indicating that the polymers adopt helical conformations with predominantly one-handed screw sense. The polymers catalyzed the asymmetric aldol reactions of acetone with aromatic aldehydes, and cyclohexanone with p-nitrobenzaldehyde. The enantioselectivities largely depended on the reaction conditions. In the asymmetric aldol reaction of acetone with aromatic aldehydes, the R-enantiomeric products were predominantly obtained except the cases with the polymer catalyst in CHCl₃. The ee of the products became higher as the reaction temperature was decreased. The polymeric catalysts were recoverable from the reaction mixture by filtration, and the recovered ones catalyzed the asymmetric aldol reaction of acetone with p-nitrobenzaldehyde without decreasing the product yield and ee. The ee was improved using the copolymers of L-proline-based and nonchiral monomers as catalysts. Copyright

Full text of DOI:10.1002/pola.24813

Synthesis of Polymers Bearing Proline Moieties in the Side Chains and
Their Application as Catalysts for Asymmetric Induction
ATSUSHI IKEDA, KAYO TERADA,* MASASHI SHIOTSUKI, FUMIO SANDA
Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura Campus,
Nishikyo-ku, Kyoto 615-8510, Japan
Received 23 March 2011; accepted 23 May 2011
DOI: 10.1002/pola.24813
Published online 22 June 2011 in Wiley Online Library (wileyonlinelibrary.com).
ABSTRACT: Novel polyphenylacetylene and polystyrene deriva-
tives carrying L-proline moieties at the side chains were synthe-
sized by the rhodium-catalyzed and radical polymerizations of
the corresponding monomers. The polyphenylacetylene deriva-
tives showed Cotton effects at the absorption region of the main
chain, indicating that the polymers adopt helical conformations
with predominantly one-handed screw sense. The polymers cat-
alyzed the asymmetric aldol reactions of acetone with aromatic
aldehydes, and cyclohexanone with p-nitrobenzaldehyde. The
enantioselectivities largely depended on the reaction conditions.
In the asymmetric aldol reaction of acetone with aromatic alde-
hydes, the R-enantiomeric products were predominantly
obtained except the cases with the polymer catalyst in CHCl3.
The ee of the products became higher as the reaction tempera-
ture was decreased. The polymeric catalysts were recoverable
from the reaction mixture by filtration, and the recovered ones
catalyzed the asymmetric aldol reaction of acetone with p-nitro-
benzaldehyde without decreasing the product yield and ee. The
ee was improved using the copolymers of L-proline-based and
C
V
nonchiral monomers as catalysts. 2011 Wiley Periodicals, Inc.
J Polym Sci Part A: Polym Chem 49: 3783–3796, 2011
KEYWORDS: catalysts; chiral; polyacetylenes; polystyrene;
proline
INTRODUCTION Organocatalysts gather much attention,
because they enable green sustainable metal-free processes.1
Some organocatalysts serve as efficient catalysts for enantiose-
lective reactions. Especially, L-proline and its derivatives have
emerged as powerful organocatalysts.2 L-Proline acts as a
bifunctional catalyst and is regarded as the simplest enzyme.3
L-Proline catalyzes various organic reactions including the aldol
reaction,4 Mannich reaction,5 Michael addition,6 and Robinson
annulation.7 Organocatalysts are often used in substantial
quantities, in some cases as much as 30 mol %.2(a),4(a) There-
fore, immobilization of organocatalysts on supports,8 such as
ionic liquid,9 silica,10 magnetite,11 polystyrene,12 and polyethyl-
ene glycol,13 has been developed to make recovery and reuse
of the catalysts possible. The preparations of polymer-sup-
ported organocatalysts are assorted into two types: The first
one is the traditional approach, in which catalysts are anch-
ored onto prefabricated solid supports by way of modified cat-
alyst precursors. The second one is the so-called ‘‘bottom-up’’
method,14 where polymer-supported catalysts are synthesized
by the polymerization of functional monomers, or by the
copolymerization with suitable comonomers.
tuted polyacetylenes show useful properties including photo-
and electroluminescence based on the conjugated double
bonds in the main chain.16 Rhodium catalysts are commonly
used to synthesize cis-stereoregular monosubstituted helical
polyacetylenes owing to their high tolerance toward polar
functional groups.17 We have synthesized a series of helical
polyacetylenes bearing various amino acids and peptide resi-
dues at the pendants to examine the chiroptical properties and
responsiveness toward external stimuli including tempera-
ture,18 solvents,19 acid/base,20 and photoirradiation.21
In the course of our study on amino acid derived helical polya-
cetylenes, we decided to examine the functions as polymer cat-
alysts for asymmetric induction. We have recently found that
helical polyphenylacetylene derivatives having L-valine and
N-methyl-L-valine moieties serve as catalysts of asymmetric
reduction of aromatic ketimines to afford optically active
amines.22 Although a large number of polymer catalysts have
been reported so far, the reports regarding the catalytic activity
in conjunction with helix chirality are limited.23 When polymer
supports adopt helical conformations, one may anticipate a
synergistic effect of the helical chirality on the enantioselectiv-
ity. This study deals with the synthesis of novel polyphenylace-
tylene derivatives bearing L-proline moieties at the side chains
together with the polystyrene counterparts, investigation of
their secondary structures, and catalytic abilities for the asym-
metric aldol reactions of acetone with aromatic aldehydes, and
On the other hand, optically active helical polymers have been
strenuously synthesized15 not only to mimic biological helices
and function but also for their potential applications such as
sensing specific molecules, separation of enantiomers, and
asymmetric catalysis. Among artificial helical polymers, substi-
*Present address: Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
Correspondence to: F. Sanda (E-mail: sanda@adv.polym.kyoto-u.ac.jp)
C
V
Journal of Polymer Science Part A: Polymer Chemistry, Vol. 49, 3783–3796 (2011) 2011 Wiley Periodicals, Inc.
SYNTHESIS OF POLYMERS AND THEIR APPLICATION, IKEDA ET AL.
3783

JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
SCHEME 1 Rhodium-catalyzed polymerization of 1–3 and radical polymerization of 4–6.
cyclohexanone with p-nitrobenzaldehyde. We selected the
‘‘bottom-up’’ approach for preparing the polymer catalysts.
Namely, the functional monomers 1–6 were synthesized and
homopolymerized, or copolymerized with comonomer 7
(Schemes 1 and 2), and the protecting groups of the proline
moieties were removed from the obtained polymers obtain
poly(1a)–(6a) and poly(1a-co-7) having nonprotected proline
pendants (Scheme 3).
tions ([a]D) were measured on a JASCO DIP-1000 digital polar-
imeter equipped with a sodium lamp as a light source.
Number- and weight-average molecular weights (Mn and Mw)
of polymers were determined by gel permeation chromatogra-
phy (GPC) on a JASCO GULLIVER system (PU-980, CO-965, RI-
930, and UV-1570) equipped with polystyrene gel columns
(Shodex columns K805L ꢀ 3), using tetrahydrofuran (THF) as
an eluent at a flow rate of 1.0 mL minꢁ1, calibrated by polysty-
rene standards at 40 ꢂC. Circular dichroism (CD) and UV-vis
absorption spectra were recorded on a JASCO J-820 spectropo-
larimeter. The absolute configuration of aldol products was
determined by high-performance liquid chromatography
(HPLC) equipped with a DAICEL CHIRALCEL AS-H using a solu-
tion of hexane/2-propanol (90/10–80/20, v/v) as an eluent at
a flow rate of 1.0 mL minꢁ1 or a DAICEL CHIRALCEL AD-H
using a solution of hexane/2-propanol (85/15, v/v) as an elu-
ent at a flow rate of 0.5 mL minꢁ1 according to the literature.24
EXPERIMENTAL
Measurements
1H and 13C NMR spectra were recorded on a JEOL EX-400 spec-
trometer. IR spectra were measured on a JASCO FT/IR-4100
spectrophotometer. Melting points (mp) were measured on a
Yanaco micromelting point apparatus. Mass spectra were meas-
ured on a JEOL JMS-HX110A mass spectrometer. Specific rota-
SCHEME 2 Copolymerization of
with 7.
1
3784
WILEYONLINELIBRARY.COM/JOURNAL/JPOLA

ARTICLE
SCHEME 3 Removal of FMOC/
fluorenylmethyl groups from the
polymers.
Materials
proline (14.1 g, 40.0 mmol), 1-(3-dimethylaminopropyl)-3-eth-
ylcarbodiimide hydrochloride (EDCꢃHCl, 16.9 g, 88.0 mmol),
and N,N-dimethyl-4-aminopꢂyridine (DMAP, 1.08 g, 8.80 mmol)
and CH2Cl2 (200 mL) at 0 C, and the resulting mixture was
stirred at room temperature overnight. It was washed with 0.5
M HCl, saturated NaHCO3 aq. then saturated NaCl aq. The or-
ganic layer was dried over anhydrous MgSO4 and concentrated
on a rotary evaporator. The residual mass was purified by silica
gel column chromatography eluted with hexane/ethyl acetate
Unless otherwise stated, reagents were commercially obtained,
and used without further purification. p-Ethynylbenzoic acid
was synthesized according to the literature.25 The solvents
used for polymerization were purified before use by the stand-
ard methods. (nbd)Rhþ[g6-C6H5Bꢁ(C6H5)3] (nbd ¼ 2,5-nor-
bornadiene) was prepared by the reaction of [(nbd)RhCl]2
with NaB(C6H5)4 as described in the literature.26
1
Monomer Synthesis
Compound 8
9-Fluorenylmethanol (15.7 g, 80.0 mmol) was added to a mix-
ture of N-(9-fluorenylmethyloxycarbonyl)-trans-4-hydroxy-L-
¼ 1/1 (v/v) to obtain 8 as a colorless solid in 54% yield. H
NMR (400 MHz, CDCl3): d 7.77–7.18 [m, 16H, Ar], 4.58–4.05
[m, 8H, ACH2OA, >CHCH2OA, >CHN<, AOH], 3.65–3.47 [m,
2H, ACH2N<], 2.21–1.66 [m, 3H, >CHOH, >CHCH2CH<]. 13C
SYNTHESIS OF POLYMERS AND THEIR APPLICATION, IKEDA ET AL.
3785

JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
NMR (100 MHz, CDCl3): d 172.2, 154.9, 154.6, 143.9, 143.8,
143.6, 143.3, 143.1, 141.3, 127.9, 127.7, 127.6, 127.1, 127.0,
125.1, 125.0, 124.9, 124.7, 120.0, 119.9, 70.0, 69.2, 67.6, 66.4,
Monomer 2
Trifluoroacetic acid (TFA, 0.20 mL, 2.7 mmol) was added to
a solution of 9 (0.35 g, 0.50 mmol) in CH2Cl2 (10 mL) at 0
ꢂC, and the resulting mixture was stirred at room tempera-
ture overnight. The resulting solution was concentrated in
vacuo to obtain 9a. It was dissolved in CH2Cl2 (10 mL), and
then, p-ethynylbenzoic acid (0.21 g, 1.4 mmol), EDCꢃHCl
(0.28 g, 1.5 mmol), DMAP (0.018 g, 0.15 mmol), and triethyl-
amine (0.15 mL, 1.1 mmol) were added to the solution at 0
ꢂC, and the resulting mixture was stirred at room tempera-
ture overnight. It was washed with 0.5 M HCl, saturated
NaHCO3 aq. then saturated NaCl aq. The organic layer was
dried over anhydrous MgSO4 and concentrated on a rotary
evaporator. The residual mass was purified by silica gel col-
umn chromatography eluted with hexane/ethyl acetate ¼ 1/
1 (v/v) to obtained 2 as a colorless solid in 47% yield. Mp
91–92 ꢂC. [a]D ꢁ0.5ꢂ (c ¼ 0.10 g dLꢁ1 in toluene at room
temperature). 1H NMR (400 MHz, CDCl3): d 7.77–7.20
[m, 20H, Ar], 6.62 [br, 1H, ANHA], 5.26–5.17 [m, 1H, >CHOA],
4.79–4.05 [m, 8H, ACH2OA, >CHCH2OA, ACHCH3A, >CHN<],
3.88–3.57 [m, 2H, ACH2N<], 3.21–3.19 [m, 1H, CHBCA],
2.36–2.31 [m, 1H, >CHCHHCH<], 2.01–1.93 [m, 1H,
>CHCHHCH<], 1.54–1.50 [m, 3H, ACH3]. 13C NMR (100 MHz,
CDCl3): d 172.4, 172.3, 171.6, 171.1, 166.1, 154.5, 154.1, 143.8,
143.6, 143.5, 143.3, 143.0, 141.4, 141.3, 133.6, 132.4, 128.3,
127.9, 127.8, 127.7, 127.6, 127.2, 127.1, 127.0, 125.9, 125.8,
125.7, 125.1, 125.0, 124.8, 124.7, 120.1, 120.0, 82.6, 79.8, 73.8,
73.0, 67.8, 67.7, 66.7, 66.6, 57.8, 57.4, 52.2, 51.8, 48.6, 47.1,
47.0, 46.8, 36.4, 35.3, 18.4 [ACH3]. IR (cm–1, KBr): 3378 (NH),
3284 (HACB), 3066 (Ar), 3040 (Ar), 2950 (CH), 2891 (CH),
2108 (CBC), 1949 (Ar), 1922 (Ar), 1745 (COO), 1708 (COO),
1656 (CONH), 1607, 1533, 1450, 1420, 1349, 1269, 1166,
1125, 1063, 857, 760, 741. HRMS. Calcd for C46H39N2O7 (m/z)
731.2757. Found: 731.2759.
58.0, 57.6, 55.1, 54.5, 47.1, 46.9, 46.8, 39.1, 38.2. IR (cmꢁ1
,
KBr): 3424 (OH), 2949 (CH), 1743 (COO), 1686 (CON), 1450,
1421, 1355, 1196, 1167, 1125, 1084, 1000, 759, 740.
Monomer 1
The title compound was synthesized by the condensation of
hydroxy group of 8 and carboxy group of p-ethynylbenzoic
acid using EDCꢃHCl/DMAP in a manner similar to the con-
densation of 9-fluorenylmethanol and N-(9-fluorenylmethy-
loxycarbonyl)-trans-4-hydroxy-L-prꢁo1line. Yield 69%. Mp 78–
ꢂ
79 C. [a]D ꢁ35.7ꢂ (c ¼ 0.10 g dL in toluene at room tem-
perature). 1H NMR (400 MHz, CDCl3): d 7.99–7.22 [m, 20H,
Ar], 5.44–5.37 [m, 1H, >CHOA], 4.61–4.06 [m, 7H, ACH2OA,
>CHCH2OA, >CHN<], 3.88–3.67 [m, 2H, ACH2N<], 3.26–
3.25 [m, 1H, CHBCA], 2.44–2.04 [m, 2H, >CHCH2CH<]. 13C
NMR (100 MHz, CDCl3): d 171.7, 165.1, 154.6, 154.1, 143.8,
143.7, 143.6, 143.5, 143.2, 143.0, 141.4, 141.3, 132.2, 132.1,
129.6, 127.8, 127.7, 127.3, 127.0, 125.0, 124.8, 120.0, 119.9,
82.6, 80.6, 80.5, 73.4, 72.5, 67.7, 66.6, 66.5, 58.0, 52.5, 52.2,
47.0, 46.9, 36.6, 35.4. IR (cmꢁ1, KBr): 3277 (HACB), 3065
(Ar), 3041 (Ar), 2952 (CH), 2109 (CBC), 1945 (Ar), 1920
(Ar), 1746 (COO), 1715 (COO), 1606, 1477, 1450, 1419,
1352, 1317, 1270, 1173, 1105, 1066, 1017, 858, 768, 759,
741. High resolution mass spectrometry (HRMS). Calcd for
C43H33NO6 (m/z) 659.2308. Found: 659.2322.
Monomer 4
The title compound was synthesized from 8 and p-vinylben-
ꢂ
zoic acid in a manner similar to 1. Yield 33%. Mp 70–72 C.
[a]D ꢁ39.2ꢂ (c ¼ 0.10 g dLꢁ1 in toluene at room temperature).
1H NMR (400 MHz, CDCl3): d8.00–7.19 [m, 20H, Ar], 6.81–6.72
[m, 1H, CH2¼¼CHA], 5.92–5.86 [m, 1H, CH2¼¼CHA], 5.45–5.39
[m, 2H, >CHOA, CH2¼¼CHA], 4.63–4.07 [m, 7H, ACH2OA,
>CHCH2OA, >CHN<], 3.94–3.68 [m, 2H, ACH2N<], 2.54–2.46
[m, 1H, >CHCHHCH<], 2.14–2.02 [m, 1H, >CHCHHCH<]. 13C
NMR (100 MHz, CDCl3): d 171.6, 165.3, 154.5, 154.0, 143.7,
143.6, 143.5, 143.3, 143.1, 142.3, 142.1, 141.2, 141.1, 141.0,
135.6, 129.8, 128.3, 127.7, 127.6, 127.5, 127.4, 127.0, 126.9,
126.8, 126.0, 124.8, 124.7, 124.6, 124.5, 119.9, 119.8, 116.7,
116.6, 73.0, 72.0, 67.5, 67.4, 66.4, 66.3, 57.9, 57.4, 52.4, 52.1,
46.9, 46.7, 46.6, 36.4, 35.3. IR (cmꢁ1, KBr): 3065 (Ar), 2924
(CH), 1750 (COO), 1709 (COO), 1607, 1450, 1420, 1352, 1317,
1271, 1177, 1103, 1067, 1016, 860, 759, 740. HRMS. Calcd for
Monomer 5
The title compound was synthesized from 9 in a manner
similar to 2. Yield 15%. Mp 86–87 C. [a]D ꢁ10.7ꢂ (c ¼ 0.10
ꢂ
g dLꢁ1 in CHCl3 at room temperature). 1H NMR (400 MHz,
CDCl3): d 7.76–7.26 [m, 20H, Ar], 6.62 [br, 1H, ANHA],
6.73–6.68 [m, 1H, CH2¼¼CHA], 6.59 [br, 1H, ANHA] 5.84–
5.77 [m, 1H, CH2¼¼CHA], 5.36–5.18 [m, 2H, >CHOA,
CH2¼¼CHA], 4.76–4.03 [m, 8H, ACH2OA, >CHCH2OA,
ACHCH3A, >CHN<], 3.76–3.57 [m, 2H, ACH2N<], 2.36–2.31
[m, 1H, >CHCHHCH<], 2.01–1.93 [m, 1H, >CHCHHCH<],
1.54–1.51 [m, 3H, ACH3]. 13C NMR (100 MHz, CDCl3): d
172.6, 172.5, 171.6, 166.6, 166.5, 154.5, 154.1, 143.9, 143.8,
143.7, 143.6, 143.5, 143.3, 143.1, 141.4, 141.3, 141.2, 141.0,
140.9, 135.8, 132.7, 132.6, 128.3, 127.9, 127.8, 127.7, 127.6,
127.4, 127.3, 127.2, 127.1, 127.0, 126.3, 125.1, 125.0, 124.9,
124.8, 124.7, 120.1, 120.0, 119.9, 116.1, 73.7, 72.8, 67.7,
67.6, 66.6, 66.5, 57.8, 57.4, 52.2, 51.8, 48.6, 47.1, 47.0, 46.8,
36.4, 35.3, 18.3. IR (cmꢁ1, KBr): 3381 (NH), 3066 (Ar), 3039
(Ar), 2950 (CH), 2888 (CH), 1949 (Ar), 1920 (Ar), 1745
(COO), 1709 (COO), 1656 (CONH), 1608, 1530, 1499, 1450,
1420, 1349, 1268, 1166, 1124, 1063, 858, 759, 741. HRMS.
Calcd for C46H40N2O7Na (m/z) 755.2728. Found: 755.2701.
C43H35NO6 (m/z) 661.2464. Found: 661.2444.
Compound 9
The title compound was synthesized from 8 and N-tert-
butoxycarbonyl-L-alanine in a manner similar to 8. Yield
91%. 1H NMR (400 MHz, CDCl3): d 7.78–7.21 [m, 16H, Ar],
5.24–5.16 [m, 1H, >CHOA], 4.95 [br, 1H, ANHA], 4.59–4.11
[m, 8H, ACH2OA, >CHCH2OA, ACHCH3A, >CHN<], 3.73–
3.59 [m, 2H, ACH2N<], 2.30–2.25 [m, 1H, >CHCHHCH<],
1.97–1.91 [m, 1H, >CHCHHCH<], 1.45 [s, 9H, ACCH3], 1.38
[t, J ¼ 7.6 Hz, 3H, ACHCH3A].
3786
WILEYONLINELIBRARY.COM/JOURNAL/JPOLA

ARTICLE
Compound 10
Monomer 3
Thionyl chloride (13 mL, 179 mmol) was added to methanol
(45 mL) at ꢁ10 ꢂC, and the resulting solution was stirred
for 10 min, and then, 12-aminododecanoic acid (9.53 g, 44.3
mmol) was added to the solution, and the resulting mixture
was stirred at room temperature overnight. The solvent was
evaporated, and then methanol (45 mL) was added to the
residue and evaporated to obtain 10 as white solid. Yield
92%. 1H NMR (400 MHz, DMSO-d6): d 7.95 [br, 2H, ANH2],
3.58 [s, 3H, AOCH3], 2.74 [br, 2H, ACH2NH2], 2.28 [t, J ¼ 7.2
Hz, 2H, ACOCH2A], 1.52 [br, 4H, ACH2CH2NH2,
ACH2CH2COA], 1.25 [br, 14H, ACH2A].
The title compound was synthesized from 8 and 12a in a
manner similar to 1. Yield 57%. Mp 47–48 ꢂC. [a]D –31.5ꢂ
(c ¼ 0.10 g dLꢁ1 in CHCl3 at room temperature). 1H NMR
(400 MHZ, CDCl3): d 7.77–7.20 [m, 20H, Ar], 6.11 [br, 1H,
ANHA], 5.22–5.16 [br, 1H, >CHOA], 4.58–4.06 [m, 7H,
ACH2OA, >CHCH2OA, >CHN<], 3.72–3.57 [m, 2H, ACH2N<],
3.45–3.41 [m, 2H, ACH2NHA], 3.18 [s, 1H, CHBCA],
2.33–2.27 [m, 3H, ACH2CH2COOA, >CHCHHCH<], 2.00–1.92
[m, 1H, >CHCHHCH<], 1.59 [br, 4H, ACH2CH2NHA,
ACH2CH2COOA], 1.26 [br, 14H, ACH2A]. 13C NMR (100 MHz,
CDCl3): d 173.1, 171.8, 166.6, 154.6, 154.2, 143.9, 143.8,
143.7, 143.3, 141.4, 141.3, 134.8, 132.2, 127.9, 127.8, 127.7,
127.6, 127.2, 127.1, 127.0, 126.8, 125.1, 125.0, 124.9, 124.8,
124.7, 120.0, 82.8, 79.4, 72.4, 71.3, 67.8, 67.7, 66.6, 66.5, 58.0,
57.6, 52.5, 52.2, 47.1, 47.0, 46.8, 40.2, 36.5, 35.4, 34.3, 34.2,
29.6, 29.4, 29.3, 29.2, 29.0, 27.0, 24.9, 24.8. IR (cmꢁ1, KBr)
3355 (NH), 3293 (HACB), 3066 (Ar), 2926 (CH), 2853 (CH),
2106 (CBC), 1945 (Ar), 1911 (Ar), 1739 (COO), 1709 (COO),
1647 (CONH), 1608, 1542, 1498, 1450, 1420, 1351, 1273,
1166, 1124, 1065, 1016, 856, 759, 740. HRMS. Calcd for
Compound 11a
The title compound was synthesized from 10 and p-ethynyl-
benzoic acid in a manner similar to 2. Yield 95%. 1H NMR
(400 MHz, CDCl3): d 7.71 [d, J ¼ 8.6 Hz, 2H, Ar], 7.54 [d, J ¼
8.6 Hz, 2H, Ar], 6.10 [br, 1H, ANHA], 3.66 [s, 3H, CH3A],
3.47–3.42 [m, 2H, ACH2NHA], 3.19 [s, 1H, CHBCA], 2.30 [t,
J ¼ 7.4 Hz, 2H, ACOCH2A], 1.61 [br, 4H, ACH2CH2NHA,
ACH2CH2COOA], 1.27 [br, 14H, ACH2A].
C55H56O7Na (m/z) 879.3980. Found: 879.3938.
Compound 11b
The title compound was synthesized from 10 and p-vinyl-
benzoic acid in a manner similar to 2. Yield 96%. 1H NMR
(400 MHz, CDCl3): d 7.73 [d, J ¼ 8.2 Hz, 2H, Ar], 7.45 [d, J ¼
8.2 Hz, 2H, Ar], 6.74 [dd, J ¼ 17.6, 10.8 Hz, 1H, CH2¼¼CHA],
6.20 [br, 1H, ANHA], 5.82 [d, J ¼ 17.6 Hz, 1H, CH2¼¼CHA],
5.34 [d, J ¼ 10.8 Hz, 1H, CH2¼¼CHA], 3.67 [s, 3H, CH3A],
3.46–3.41 [m, 2H, ACH2NHA], 2.30 [t, J ¼ 7.4 Hz, 2H,
ACH2COOA], 1.61 [br, 4H, ACH2CH2NHA, ACH2CH2COOA],
1.27 [br, 14H, ACH2A].
Monomer 6
The title compound was synthesized from 8 and 12b in a
manner similar to 1. Yield 66%. Mp 49–50 ꢂC. [a]D ꢁ16.3ꢂ
(c ¼ 0.10 g dLꢁ1 in toluene at room temperature). 1H NMR
(400 MHz, CDCl3): d 7.77–7.21 [m, 20H, Ar], 6.73 [dd, J ¼
17.6, 11.0 Hz, 1H, CH2¼¼CHA], 6.11 [br, 1H, ANHA], 5.82 [d,
J ¼ 17.6 Hz, 1H, CH2¼¼], 5.34 [d, J ¼ 11.0 Hz], 5.24–5.17 [br,
1H, >CHOA], 4.62–4.06 [m, 7H, ACH2OA, >CHCH2OA,
>CHN<], 3.73–3.66 [m, 2H, ACH2N<], 3.69–3.44 [m, 2H,
ANHCH2A],
2.33–2.27
[m,
3H,
ACH2CH2COOA,
Compound 12a
>CHCHHCH<], 2.00–1.93 [m, 1H, >CHCHHCH<], 1.62 [br,
4H, ACH2CH2NHA, ACH2CH2COOA], 1.26 [br, 14H, ACH2A].
13C NMR (100 MHz, CDCl3): d 173.2, 171.9, 167.1, 154.7,
154.2, 143.9, 143.8, 143.6, 143.5, 143.3, 143.1, 141.4, 141.3,
140.5, 136.0, 133.9, 127.9, 127.8, 127.7, 127.6, 127.2, 127.1,
127.0, 126.3, 125.1, 125.0, 124.9, 124.8, 124.7, 115.8, 72.4,
71.4, 67.8, 67.7, 67.0, 66.7, 58.0, 57.6, 52.6, 52.2, 47.1, 47.0,
46.9, 40.1, 36.6, 35.5, 34.3, 34.2, 29.7, 29.5, 29.4, 29.3, 29.2,
29.1, 29.0, 27.0, 24.9, 24.8. IR (cmꢁ1, KBr): 3422 (NH), 3066
(Ar), 2926 (CH), 2852 (CH), 1736 (COO), 1718 (COO), 1708
(COO), 1655 (CONH), 1638, 1560, 1543, 1450, 1420, 1350,
1286, 1166, 1112, 1072, 855, 758, 741. HRMS. Calcd for
NaOH aq. (0.5 M, 13 mL, 6.5 mmol) was added toꢂsolution of
11a (0.72 g, 2.0 mmol) in acetone (13 mL) at 0 C, and the
resulting mixture was stirred at room temperature overnight.
The resulting solution was concentrated on a rotary evapora-
tor. The residual mass was dissolved in CH2Cl2, and it was
washed 0.5 M HCl, saturated NaCl aq. The organic layer was
dried over anhydrous MgSO4 and concentrated on a rotary
evaporator, and the residual mass was purified by recrystalli-
zation from hexane/ethanol to obtain 12a as pale orange
solid. Yield 89%. 1H NMR (400 MHz, DMSO-d6): d 11.94 [br,
1H, ACOOH], 8.51 [br, 1H, ANHA], 7.83 [d, J ¼ 8.7 Hz, 2H,
Ar], 7.55 [d, J ¼ 8.7 Hz, 2H, Ar], 4.35 [s, 1H, CHBCA], 3.26–
C55H59N2O7 (m/z) 859.4322. Found: 859.4324.
3.21 [m, 2H, ACH2NHA], 2.18 [t,
ACH2COOA], 1.48 [br, 4H, ACH2CH2NHA, ACH2CH2COOA],
1.24 [br, 14H, ACH2A].
J
¼
7.3 Hz, 2H,
Monomer 7
The title compound was synthesized from methanol and
p-ethynylbenzoic acid in a manner similar to 8. Yield 72%.
1
ꢂ
Compound 12b
Mp 78 C. H NMR (400 MHz, CDCl3): d 8.00 [d, J ¼ 8.4 Hz,
2H, Ar], 7.55 [d, J ¼ 8.4 Hz, 2H, Ar], 3.93 [s, 3H, CH3A], 3.23
[s, 1H, CHBCA]. 13C NMR (100 MHz, CDCl3): d 166.3, 132.0,
130.1, 129.4, 126.7, 82.7, 80.1, 52.2. IR (cmꢁ1, KBr): 3244
(HACB), 3038 (Ar), 3007 (Ar), 2952 (CH), 2104 (CBC),
1945 (Ar), 1704 (COO), 1607 (Ar), 1560, 1435 (Ar), 1403,
1311, 1280, 1193, 1175, 1110, 1017, 959, 860, 837, 773,
722, 680. HRMS. Calcd for C10H9O2 (m/z) 160.0597. Found:
161.0594.
The title compound was synthesized from 11b in a manner
similar to 12a. 1H NMR (400 MHz, DMSO-d6): d 11.97 [br,
1H, ACOOH], 8.41 [br, 1H, ANHA], 7.91 [d, J ¼ 8.2 Hz, 2H,
Ar], 7.81 [d, J ¼ 8.2 Hz, 2H, Ar], 6.78 [dd, J ¼ 17.6, 11.0 Hz,
1H, CH2¼¼CHA], 5.94 [d, J ¼ 17.6 Hz, 1H, CH2¼¼CHA], 5.36
[d,
J
¼ 11.0 Hz, 1H, CH2¼¼CHA], 3.25–3.23 [m, 2H,
ACH2NHA], 2.18 [t, J ¼ 7.4 Hz, 2H, ACH2COOA], 1.49 [br,
4H, ACH2CH2NHA, ACH2CH2COOA], 1.24 [br, 14H, ACH2A].
SYNTHESIS OF POLYMERS AND THEIR APPLICATION, IKEDA ET AL.
3787

JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
Polymerization of 1–3
MHz, CDCl3): d 7.62–7.14 [br, 20H, Ar], 6.16 [br, 1H, ANHA],
5.19 [br, 1H, >CHOA], 4.62–3.97 [br, 8H, ACH2OA,
>CHCH2OA >CHN<, ACHCH3A], 3.70 [br, 2H, ACH2N<],
2.29 [br, 1H, >CHCHHCH<], 1.95 [br, 1H, >CHCHHCH<],
1.55 [br, 6H, ACH3, ACH2CHArA]. IR (cmꢁ1, KBr): 3424
(NH), 3065 (Ar), 2940 (CH), 1745 (COO), 1711 (COO), 1656
(CONH), 1610, 1527, 1497, 1478, 1450, 1419, 1347, 1267,
1197, 1166, 1124, 1066, 853, 759, 741. Poly(6): [a]D ꢁ16.3ꢂ
(c ¼ 0.10 g dLꢁ1 in toluene at room temperature). 1H NMR
(400 MHz, CDCl3): d7.72–7.24 [br, 20H, Ar], 6.30 [br, 1H,
ANHA], 5.18 [br, 1H, >CHOA], 4.51–4.06 [br, 7H, ACH2OA,
>CHN<], 3.70–3.35 [br, 4H, ACH2N<, ANHCH2A], 2.27
[br, 3H, >CHCHHCH<, ACH2CH2COOA], 1.93 [br, 1H,
>CHCHHCH<], 1.66–1.60 [br, 7H, ACH2CHArA, ACH2CH2NHA,
ACH2CH2COOA], 1.46–1.18 [br, 14H, ACH2A]. IR (cmꢁ1, KBr):
3400 (NH), 3065 (Ar), 3040 (Ar), 2925 (CH), 2852 (CH), 1948
(Ar), 1919 (Ar), 1739 (COO), 1710 (COO), 1637 (CONH), 1542,
1499, 1450, 1418, 1350, 1317, 1289, 1165, 1120, 1066, 1017,
853, 759, 740.
The polymerization of 1–3 was carried out in a glass tube
equipped with a three-way stopcock under nitrogen. THF
(1.0 mL) was added to a monomer (0.20 mmol) and
(nbd)Rhþ[g6-C6H5Bꢁ(C6H5)3] (1.0 mg, 2.0 lmol), and the
resulting mixture was vigorously stirred. It was kept in a
water bath at 30 ꢂC for 1 h. The resulting mixture was
poured into methanol (50 mL) to precipitate a polymer. It
was separated by filtration using a membrane filter (ADVAN-
TEC H100A047A), and dried under reduced pressure.
Polymerization of 4–6
The polymerization of 4–6 was carried out in a glass tube
equipped with a three-way stopcock under nitrogen. A solu-
tion of 2,20-azobis(isobutyronitrile) (AIBN, 1.6 mg, 10 lmol)
in C6H5Cl (0.5 mL) was added to a solution of a monomer
(0.2 mmol) in C6H5Cl (0.5 mL), and the resulting mixtuꢂre
was vigorously stirred. It was kept in a water bath at 60 C
for 96 h. The resulting mixture was poured into diethyl ether
(50 mL) to precipitate a polymer. It was separated by filtra-
tion using a membrane filter (ADVANTEC H100A047A), and
dried under reduced pressure.
Cleavage of 9-Fluorenylmethyloxycarbonyl and
9-Fluorenylmethyl Groups
Piperidine (0.90 mL, 9.1 mmol) was added to a solution of a
monomer or a polymer (0.090 mmol) in CH2Cl2 (0.90 mL),
and the resulting mixture was stirred at room temperature
for 1 h. Hexane (10 mL) was added to the reaction mixture
to precipitate a deprotected monomer or a polymer. It was
separated by filtration using a filter paper, and washed with
CHCl3 (1 mL), and dried under reduced pressure. Compound
1a was prepared from 1 according to the similar method,
and isolated by silica gel column chromatography eluted
with hexane/ethyl acetate.
Spectroscopic Data of the Polymers
Poly(1): [a]D ꢁ61.4ꢂ (c ¼ 0.10 g dLꢁ1 in toluene at room
temperature). 1H NMR (400 MHz, CDCl3): d 7.51–6.76 [br,
20H, Ar], 5.70 [br, 1H, ACH¼¼CArA], 5.16 [br, 1H, >CHOA],
4.47–3.54 [br, 9H, ACH2OA, >CHCH2OA, >CHN<, ACH2N<],
2.26 [br, 1H, >CHCHHCH<], 1.95 [br, 1H, >CHCHHCH<]. IR
(cmꢁ1, KBr): 3065 (Ar), 2951 (CH), 2890 (CH), 1945 (Ar),
1920 (Ar), 1715 (COO), 1605, 1477, 1450, 1417, 1348,
1317, 1269, 1177, 1118, 1102, 1067, 1017, 856, 758, 740.
Poly(2): [a]D þ337.0ꢂ (c ¼ 0.10 g dLꢁ1 in CHCl3 at room
1
temperature). H NMR (400 MHz, CDCl3): d 7.54–7.04 [br, Ar,
Spectroscopic Data of the Deprotected Monomers and
Polymers
20H], 6.21 [br, 1H, ANHA], 5.52 [br, 1H, ACH¼¼CArA], 5.10
[br, 1H, >CHOA], 4.80–3.08 [br, 10H, ACH2OA, >CHCH2OA,
ACHCH3A, >CHN<, ACH2N<], 2.35–1.02 [br, 5H,
>CHCH2CH<, ACH3]. IR (cmꢁ1, KBr): 3433 (NH), 2950 (CH),
2842 (CH), 2809 (CH), 1736 (COO), 1709 (COO), 1637
(CONH), 1543, 1450, 1420, 1351, 1317,ꢁ11275, 1164, 1114,
740. Poly(3): [a]D ꢁ28.9ꢂ (c ¼ 0.10 g dL in CHCl3 at room
ꢁ1
ꢂ
1a: Mp 233–235 C. [a]D þ4.1ꢂ (c ¼ 0.10 g dL in methanol
at room temperature). 1H NMR (400 MHz, CD3OD): d 8.01
[d, J ¼ 8.0 Hz, 2H, Ar], 7.55 [d, J ¼ 8.0 Hz, 2H, Ar], 5.51 [m,
1H, >CHOA], 3.97 [m, 1H, >CHNHA], 3.56 [m, 1H,
ACHHNHA], 3.22 [m, 2H, ACHHNHA, CHB], 2.45 [m, 1H,
>CHCHHCH<], 2.22 [m, 1H, >CHCHHCH<]. 13C NMR (100
MHz, CDCl3): d 178.2 [ACOOH], 165.5 [ACOOA], 132.1,
130.0, 129.6, 127.0 [Ar], 82.8 [HCBCA], 80.2 [HCBCA], 75.9
[>CHOA], 61.2 [>CHNHA], 52.3 [ACH2NHA], 37.7
[>CH2CHCH2<]. IR (cmꢁ1, KBr): 3423 (NH), 3296 (CH), 3179
(Ar), 2950 (CH), 2841 (CH), 2809, 2761, 2738, 2629, 2514,
2414, 2146, 2104 (CBC), 2029, 1993, 1871, 1714 (COO),
1628 (NH), 1587, 1460, 1435, 1406, 1296, 1275, 1178,
1163, 1108, 1082, 1031, 948, 860, 770, 696. HRMS. Calcd
for C14H14NO4 (m/z) 260.0917. Found: 260.0916. Poly(1a):
[a]D þ86.6ꢂ (c ¼ 0.10 g dLꢁ1 in H2O at room temperature).
1H NMR (400 MHz, D2O): d 8.70–6.75 [br, 4H, Ar], 6.48–5.98
[br, 1H, ACH¼¼CArA], 5.98–5.52 [br, 1H, >CHOA], 4.50–4.19
[br, 1H, >CHNHA], 4.18–3.78 [br, 1H, ACHHNHA], 3.76–3.40
[br, 1H, ACHHNHA], 3.12–2.38 [br, 2H, >CHCH2CH<]. IR
(cmꢁ1, KBr): 3414 (NH), 2958 (CH), 2732, 1718 (COO),
1628, 1605, 1406, 1340, 1317, 1270, 1179, 1109, 1016, 766,
709. Poly(2a): [a]D þ134.5ꢂ (c ¼ 0.10 g dLꢁ1 in H2O at
room temperature). 1H NMR (400 MHz, D2O): d 8.25–7.66
1
temperature). H NMR (400 MHz, CDCl3): d 7.62–7.18 [br, Ar,
20H], 6.43 [br, 1H, ANHA], 5.69 [br, 1H, ACH¼¼CArA], 5.09
[br, 1H, >CHOA], 4.44–3.99 [br, 7H, ACH2OA, >CHCH2OA
>CHN<], 3.73–3.35 [br, 4H, ACH2N<, ANHCH2A], 2.19 [br,
3H, >CHCHHCH<, ACH2CH2COOA], 1.89 [br, 1H,
>CHCHHCH<], 1.70–1.23 [br, 18H, ACH2A]. IR (cmꢁ1, KBr):
3433 (NH), 3066 (Ar), 3040 (Ar), 2926 (CH), 2852 (CH),
1737 (COO), 1709 (COO), 1638 (CONH), 1542, 1450, 1419,
1351, 1164, 1120, 1069, 860, 759, 740. Poly(4): [a]D ꢁ41.0ꢂ
(c ¼ 0.10 g dLꢁ1 in toluene at room temperature). 1H NMR
(400 MHz, CDCl3): d 7.63–7.25 [br, 19H, Ar], 6.46 [br, 1H,
Ar], 5.38 [br, 1H, >CHOA], 4.29–3.49 [br, 9H, ACH2OA,
>CHCH2OA, >CHN<, ACH2N<], 2.48 [br, 1H, >CHCHHCH<],
2.04 [br, 1H, >CHCHHCH<], 1.42–1.22 [br, 3H, ACH2CHArA].
IR (cmꢁ1, KBr): 3065 (Ar), 2948 (CH), 1948 (Ar), 1756
(COO), 1713 (COO), 1608, 1477, 1450, 1418, 1350, 1271,
1178, 1102, 1018, 857, 759, 740. Poly(5): [a]D ꢁ12.9ꢂ (c ¼
0.10 g dLꢁ1 in CHCl3 at room temperature). 1H NMR (400
3788
WILEYONLINELIBRARY.COM/JOURNAL/JPOLA

ARTICLE
SCHEME 4 Synthesis of monomers 1–6.
SYNTHESIS OF POLYMERS AND THEIR APPLICATION, IKEDA ET AL.
3789

JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
TABLE 1 Polymerization of 1–6
eluted with hexane/ethyl acetate ¼ 4/1 (v/v) to obtain 14a.
The absolute configuration of 14a was determined by chiral
HPLC (CHIRALCEL AS-H) according to the literature.24
Polymer
Yieldc (%)
Mn
Mw/Mn
d
d
Monomer
RESULTS AND DISCUSSION
1a
2a
3a
4b
5b
6b
a
97
86
77
90
89
81
45,200
25,800
79,500
17,900
14,200
14,100
1.95
2.21
2.52
2.09
2.24
2.04
Synthesis and Secondary Structures of the Polymers
Novel phenylacetylene- and styrene-derived monomers 1–6
were synthesized according to Scheme 4. The structures of
the monomers were confirmed by H NMR, 13C NMR, and IR
1
spectroscopies besides HRMS. The polymerization of 1–3
was conducted with (nbd)Rhþ[g6-C6H5Bꢁ(C6H5)3] in THF at
30 ꢂC for 1 h, and that of 4–6 was conducted in the pres-
ence of AIBN in C6H5Cl at 60 ꢂC for 96 h. Table 1 summa-
rizes the conditions and results of the polymerizations. The
monomers satisfactorily underwent polymerization to afford
the corresponding polymers [poly(1)–poly(6)] with moder-
ate molecular weights (14,100–79,500) in 77–97% yields.
Poly(1)–poly(6) were soluble in CHCl3, CH2Cl2, THF, N,N-
dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).
Catalyst: (nbd)Rhþ[g6-C6H5Bꢁ(C6H5)3]. Conditions: [M]0 ¼ 0.20 M, [M]0/
[Cat] ¼ 100 in THF at 30 ꢂC for 1 h.
b
Initiator: 2,20-azobis(isobutyronitrile) (AIBN). Conditions: [M]0 ¼ 0.20
M, [M]0/[Initiator] ¼ 20 in C6H5Cl at 60 ꢂC for 96 h.
c
MeOH- or Et2O-insoluble part.
d
Estimated by GPC (THF, PSt standards).
[br, 2H, Ar], 7.55–6.70 [br, 2H, Ar], 6.44–6.07 [br, 1H,
ACH¼¼CArA], 5.99–5.88 [br, 1H, >CHOA], 4.48–4.14 [br, 1H,
>CHNHA], 4.00–3.55 [br, 2H, ACH2NHA], 2.86–2.23 [br, 2H,
>CHCH2CH<], 1.99–1.50 [br, 3H, ACH3]. IR (cmꢁ1, KBr):
3410 (NH), 2950 (CH), 2843 (CH), 2811, 2763, 2741, 2527,
2428, 1736 (COO), 1638 (CONH), 1593, 1543, 1459, 1388,
1164, 1081, 1032, 949, 861. Poly(3a): IR (cmꢁ1, KBr): 3427
(NH), 2949 (CH), 2929 (CH), 2850, 2809, 2742, 2633, 2526,
2428, 1736 (COO), 1637 (CONH), 1543, 1498, 1459, 1438,
1380, 1314, 1164, 1107, 1081, 1032, 852. Poly(4a): [a]D
þ1.5ꢂ (c ¼ 0.10 g dLꢁ1 in H2O at room temperature). 1H
NMR (400 MHz, D2O): d 8.45–6.46 [br, 4H, Ar], 5.50–5.28
[br, 1H, >CHOA], 4.17–3.38 [br, 3H, >CHNHA, ACH2NHA],
2.60–2.00 [br, 3H, >CHCH2CH<, ACH2CHArA], 1.60–1.35 [br,
2H, ACH2CHArA]. IR (cmꢁ1 KBr): 3407 (NH), 2949 (CH),
2842, 2809, 2738, 2525, 2427, 1715 (COO), 1608, 1457,
1418, 1273, 1031, 949, 861, 770, 709. Poly(5a): [a]D ꢁ9.5ꢂ
(c ¼ 0.10 g dLꢁ1 in H2O at room temperature). 1H NMR
(400 MHz, D2O): d 8.50–6.29 [br, 4H, Ar], 5.60–5.35 [br, 1H,
>CHOA], 4.28–3.83 [br, 1H, >CHNHA]], 3.82–3.44 [br, 2H,
ACH2NHA], 2.60–2.16 [br, 2H, >CHCH2CH<], 1.75–0.95 [br,
6H, ACH2CHArA, ACH3]. IR (cmꢁ1 KBr): 3395 (NH), 3284,
2951 (CH), 2843, 2808, 2744, 2635, 2527, 2428, 2151,
2003, 1890, 1740 (COO), 1638 (CONH), 1593, 1542, 1500,
1459, 1386, 1318, 1277, 1164, 1120, 1080, 1032, 948, 862.
Poly(6a): IR (cmꢁ1, KBr): 3396 (NH), 2949 (CH), 2843 (CH),
2809, 2738, 2632, 2524, 2427, 2151, 1890, 1736 (COO),
1637 (CONH), 1543, 1459, 1389, 1316, 1163, 1032, 948,
862.
The copolymerizationꢂof 1 and 7 was carried out with vari-
ous feed ratios at 30 C in a manner similar to the homopo-
lymerization of 1–3. The corresponding copolymers with
Mn’s ranging from 13,400 to 41,800 were obtained in good
yields as summarized in Table 2. The monomer unit ratios in
the obtained copolymers were calculated from the integra-
tion ratios of the methylene and methine protons of unit 1
(4.65–4.05 ppm) between methyl protons of unit 7 (3.90–
3.60 ppm), which agreed well with the feed monomer ratios
as expected from the quantitative polymer yields (93–97%).
The 9-fluorenylmethyloxycarbonyl (FMOC) and 9-fluorenyl-
methyl groups of poly(1)–poly(6) were removed from the
polymers using piperidine to obtain the corresponding
deprotected polymers [poly(1a)–poly(6a)] (Scheme 3). Quan-
titative removal was confirmed by 1H NMR and IR spectros-
copies besides gravimetry in all the case. Poly(1a), poly(2a),
poly(4a), and poly(5a) were soluble in H2O, although insolu-
ble in CHCl3, CH2Cl2, THF, MeOH, DMF, and DMSO. On the
other hand, poly(3a) and poly(6a) were insoluble in all these
solvents. The presence of long spacers between the main
TABLE 2 Copolymerization of 1 with 7a
Feed
Ratio
Unit
Ratioc
d
d
1
7
Yieldb (%)
1
7
Mn
Mw/Mn
67
50
33
20
10
a
33
50
67
80
90
94
93
95
97
96
65
45
27
20
5
35
55
73
80
95
13,400
16,400
41,800
20,000
23,800
1.91
1.82
1.41
1.79
2.09
Typical Procedure of the Aldol Reaction
Acetone (0.2 mL, 2.7 mmol) and a solvent (0.8 mL) were
added to aldehyde 13a (45 mg, 0.30 mmol) and a catalyst
(0.09 mmol), and the resulting mixture was stirred at a set
temperature. The reaction was quenched with saturated
NaCl aq. (1.0 mL), and the product was extracted with ethyl
acetate (30 mL). The organic layer was dried over anhydrous
MgSO4 and concentrated on a rotary evaporator. The residual
mass was purified by silica gel column chromatography
Catalyst: (nbd)Rhþ[g6-C6H5Bꢁ(C6H5)3]. Conditions: [M]total
[M]total/[Cat] ¼ 100 in THF at 30 ꢂC for 1 h.
¼
0.20 M,
b
MeOH-insoluble part.
Estimated by 1H NMR.
c
d
Estimated by GPC (THF, PSt standards).
3790
WILEYONLINELIBRARY.COM/JOURNAL/JPOLA

ARTICLE
FIGURE 1 Top: CD and UV–vis
spectra of poly(1)–poly(3) mea-
sured in toluene, CHCl3, THF and
DMF (c ¼ 0.20 mM) at 0 ꢂC. Mid-
dle: CD and UV–vis spectra of
poly(1)–poly(3) measured in tolu-
ene, DMF and CHCl3 (c ¼ 0.20
mM) at various temperatures.
Bottom: CD and UV–vis spectra
of poly(1a) and poly(2a) mea-
sured in H2O (c ¼ 0.20 mM) at
20–80 ꢂC. Poly(3a) was insoluble
in these solvents.
chain and nonprotected proline moieties may enhance the
intermolecular aggregation leading to the insolubility of
these two polymers.
UV–vis spectra of poly(1) depended on the solvents. Poly(1)
showed the Cotton effects most strongly in toluene. The in-
tensity gradually decreased as the temperature was
increased in toluene, indicating that the bias of the screw
sense was thermally reduced. In a similar fashion, the CD in-
tensity of poly(2) gradually decreased by raising tempera-
ture in DMF. Simultaneously, the UV–vis absorption band
around 345 nm decreased, whereas that around 440 nm
increased. It is likely that the one-handedness of helicity of
Figure 1 depicts the CD and UV–vis spectra of poly(1)–
poly(3), poly(1a), and poly(2a) measured in various solvents
at 0–80 ꢂC. Poly(1), poly(2), and poly(3) exhibited intense
Cotton effects at a UV-absorption area based on the conju-
gated main chain under certain conditions, indicating that
they adopt helical conformations with predominantly one-
handed screw sense. The signs and wavelengths of CD and
poly(2) decreased accompanying transformation into
a
SYNTHESIS OF POLYMERS AND THEIR APPLICATION, IKEDA ET AL.
3791

JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
TABLE 3 Asymmetric Aldol Reaction of Acetone with
p-Nitrobenzaldehydea
14a
Run Catalyst
Solvent Yieldb (%) eec (%)
1
L-Proline
DMF
43
40
0
72 (R)
80 (R)
2
trans-4-Hydroxy-L-proline DMF
d
3
1
DMSO
_
SCHEME 5 Asymmetric aldol reaction of acetone with benzal-
d
4
Poly(1)
1a
DMSO
CHCl3
DMSO
H2O
0
_
dehyde derivatives.
5
54
38
57
57
21
64 (R)
82 (R)
0
6
1a
temperature from 80 to 0 ꢂC. Interestingly, poly(3) showed
completely no Cotton effect in THF and DMF but strong one
in CHCl3. The CD intensity in CHCl3 largely decreased by
7
1a
8
Poly(1a)
Poly(1a)
Poly(1a)
Poly(1a)
Poly(1a)
Poly(1a)
Poly(2a)
Poly(2a)
Poly(3a)
Poly(3a)
Poly(4a)
Poly(4a)
Poly(5a)
Poly(5a)
Poly(6a)
Poly(6a)
CHCl3
MeOH
8 (S)
0
9
ꢂ
raising temperature from 0 to 20 C, and became zero at 40
10
11
12
13
14
15
16
17
18
19
20
21
22
23
a
Acetone 10
8 (R)
18 (R)
10 (R)
0
ꢂC. The helicity of poly(3) was very susceptible to heat
among the present polymers, presumably because of the
long distance between the chiral proline moieties and main
chain. Because the UV–vis intensity also decreased according
to the CD intensity, it is considered that the CD spectroscopic
change was not caused by decrease of one-handedness of
helical sense but transformation of helix into random coil.
DMF
27
13
45
48
38
25
24
42
31
30
31
26
21
DMSO
H2O
CHCl3
DMF
6 (S)
18 (R)
18 (S)
8 (R)
4 (S)
12 (R)
0
CHCl3
DMF
The CD spectroscopic pattern of poly(1a) was different from
those of poly(1). It seems that the presence and absence of
FMOC/fluorenylmethyl groups affect the conformations of
poly(1) and poly(1a) in addition to the difference of solvents
for measurement. Poly(2a) exhibited CD spectroscopic pat-
tern different from those of poly(2) as well. The thermal
responsiveness of CD signals of poly(2a) was smaller than
that of poly(1a). This may be caused by the presence of am-
ide groups between the proline moieties and main chain of
poly(2a). As the rotational barrier of C(¼¼O)ANH single bond
CHCl3
DMF
CHCl3
DMF
10 (R)
8 (S)
2 (R)
CHCl3
DMF
Conditions: p-nitrobenzaldehyde (0.3 M) with a catalyst (30 mol %) in
solvent/acetone (4/1, v/v) at 25 ꢂC for 24 h.
b
Isolated yield.
c
Estimated by chiral HPLC.
d
Not determined.
TABLE 4 Effect of Reaction Conditions on the Asymmetric
Aldol Reactiona
random structure that has a conjugation length longer than
that of the helical structure. Poly(2) reversibly recovered the
original CD and UV–vis spectroscopic patterns upon cooling
Amount of
Poly(1a)
Temperature
(ꢂC)
Time
(h)
Yieldb
(%)
eec
Run
(mol %)
(%)
1
3
10
30
30
30
30
30
30
30
30
60
25
25
40
25
25
25
25
0
24
24
24
24
16
10
4
10
32
39
57
28
33
12
51
28
18
54
4 (S)
4 (S)
2
3
6 (S)
4
8 (S)
5
10 (S)
10 (S)
12 (S)
18 (S)
16 (S)
20 (S)
14 (S)
6
7
8
48
24
96
48
9
0
10
11
a
ꢁ20
0
Conditions: p-nitrobenzaldehyde (0.3 M) with poly(1a) in CHCl3/ace-
tone (4/1, v/v).
b
Isolated yield.
c
CHART 1 Structure of 1a.
Estimated by chiral HPLC.
3792
WILEYONLINELIBRARY.COM/JOURNAL/JPOLA

ARTICLE
TABLE 5 Asymmetric Aldol Reaction of Acetone with
p-Nitrobenzaldehyde Catalyzed by Poly(1a-co-7)a
Solvent
Unit
Ratio
CHCl3
DMF
1a
100
7
Run Yieldb (%) eec (%) Run Yieldb (%) eec (%)
0
1
3
5
7
9
51
40
46
69
64
91
18 (S)
26 (S)
20 (S)
28 (S)
20 (S)
18 (S)
2
4
16
14
28
56
41
41
16 (R)
30 (R)
38 (R)
32 (R)
44 (R)
24 (R)
SCHEME 6 Asymmetric aldol reaction of cyclohexanone with
p-nitrobenzaldehyde.
65 35
45 55
27 73
20 80
6
8
10
12
trans-4-hydroxy-L-proline, 1a, and the polymers (Runs 1, 2,
and 5–23). Nonprotected amino and carboxy groups of the
proline moiety were indispensable to the aldol reaction.
Monomer 1a catalyzed the reaction to give 14a with 64%
and 82% ee in CHCl3 and DMSO, respectively (Runs 5 and
6). Poly(1a) gave 14a with lower ee values (0–18%) than
the cases of 1a. Interestingly, the predominant configuration
of 14a obtained by the reaction in CHCl3 (Run 8) was oppo-
site to that obtained by the reaction in acetone, DMF, and
DMSO (Runs 10–12). The inversion of predominant chiral
configuration depending on solvents was also observed in
the reactions catalyzed by poly(2a)–poly(4a) and poly(6a)
(Runs 14–19, 22, and 23). This solvent-dependent chirality
inversion was not observed in the case using 1a as a cata-
lyst. When the reaction was carried out in H2O, the ee of the
product was 0% in the cases of both 1a and poly(1a) (Runs
7 and 13).
5
95 11
a
Conditions: p-nitrobenzaldehyde (0.3 M) with poly(1a-co-7) (30 mol %)
in solvent/acetone (4/1, v/v) at 0 ꢂC for 48 h.
b
Isolated yield.
Estimated by chiral HPLC.
c
is higher than that of C(¼¼O)AO, the conformation around
the phenylene moiety of poly(2a) seems more rigid than
that of poly(1a), leading to the higher stability of helical
structure. On the other hand, polystyrene derivatives
poly(4), poly(5), poly(6), poly(4a), and poly(5a) showed no
CD signals, indicating the absence of chiral higher-order
structures. Poly(1-co-7)s and poly(1a-co-7) with a unit ratio
of 5:95 exhibited no clear CD signals at an absorption region
of the main chain in CHCl3 and DMF. The CD spectra
of poly(3a) and poly(6a) could not be measured because of
the insolubility in organic solvents and H2O as mentioned
above.
Recovering and recycling use of catalysts are important for
practical usage. We examined recovering and recycling of
poly(3a), because it was easily recoverable from the reaction
mixture by filtration because of the insolubility in DMF. The
recovered poly(3a) catalyzed the asymmetric aldol reaction
of acetone with p-nitrobenzaldehyde without decreasing the
product yield and ee.
Asymmetric Aldol Reaction
Table 3 summarizes the results of asymmetric aldol reaction
of acetone with p-nitrobenzaldehyde 13a in the presence of
poly(1) and poly(1a)–poly(6a) together with the results
using L-proline, trans-4-hydroxy-L-proline monomers, 1 and
1a (Chart 1) as catalysts (Scheme 5). No aldol product was
obtained in the presence of 1 and poly(1) having protected
proline moieties (Runs 3 and 4). On the other hand, aldol
14a was obtained in 7–57% in the presence of L-proline,
Table 4 summarizes the effect of catalyst amount, reaction
temperature and time using poly(1a) as a catalyst. The prod-
uct yield and ee tended to increase as the catalyst amount
TABLE 6 Effect of Aldehyde Substituents on the Asymmetric
Aldol Reactiona
TABLE 7 Asymmetric Aldol Reaction of Cyclohexanone and
p-Nitrobenzaldehydea
Yield (%)b
ee (%)c
Syn
Solvent
CHCl3
Yieldb (%)
DMF
Yieldb (%)
Run Catalyst Solvent Anti Syn Anti
48 (2S,10R) 68 (2S,10S)
40 (2S,10R) 38 (2S,10S)
24 (2S,10R) 16 (2S,10S)
64 (2S,10R) 10 (2R,10R)
14 (2S,10R) 2 (2R,10R)
Aldehyde
eec (%)
eec (%)
1
2
3
4
5
a
L-Proline DMSO
L-Proline DMF
Poly(1a) CHCl3
Poly(1a) DMF
Poly(1a) H2O
12
20
28
21
39
17
19
27
26
42
13b
13c
13d
a
28
13
6
14 (S)
10 (S)
12 (S)
11
8 (R)
4
18 (R)
d
Trace
–
Conditions: aldehydes (0.3 M) with poly(1a) (30 mol %) in solvent/ace-
tone (4/1, v/v) at 25 ꢂC for 24 h.
Conditions: p-nitrobenzaldehyde (0.3 M) with a catalyst (30 mol %) in
solvent/cyclohexanone (3/1, v/v) at 25 ꢂC for 24 h.
b
Isolated yield.
c
b
Estimated by chiral HPLC.
Isolated yield.
d
c
Not determined.
Estimated by chiral HPLC.
SYNTHESIS OF POLYMERS AND THEIR APPLICATION, IKEDA ET AL.
3793

JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
was increased (Runs 1, 2, and 4). Shortening of the reaction
time did not affect the ee so much, whereas lowered the
yield (Runs 4–7, 8, and 9). To check the possibility of race-
mization of the product during the reaction,27 a CHCl3 solu-
tion of an isolated sample of (R)-rich 14a was left in the
presence of poly(1a). As the ee did not decrease even after
72 h, it is considered tꢂhat the racemization of the product is
negligibly small. At 40 C, a yield and an ee value were lower
than those at 25 ꢂC (Runs 3 and 4). The reaction tempera-
ture largely affected the yield and ee. The yield became the
It should be noted that the predominant chiral configuration
of syn-14 obtained by the reaction in DMF and H2O was op-
posite to that obtained by the reaction in CHCl3 (Runs 3–5),
and that obtained using L-proline as a catalyst (Runs 1 and
2). It is assumed that the helical structure with predomi-
nantly one-handed screw sense affects the chirality selectiv-
ity of the product. Namely, the main chain itself may interact
with the transition state of the aldol reaction, leading to the
inversion of the predominant configuration of the product.
However, further study is necessary to confirm this assump-
tion, for example, (i) preparation of both right- and left-
handed helical polymers bearing the proline-based same chi-
ral substituents, (ii) respective introductions of enantiomeric
prolines to a predominantly one-handed helical polymer syn-
thesized beforehand, (iii) preparation of helical polymers
bearing proline-mimetic achiral substituents, and (iv) investi-
gation of their catalytic activities.
ꢂ
highest at 25 C, when 30 mol % of poly(1a) was used (Run
4). The ee became higher as the temperature was decreased,
though a longer reaction time was necessary to obtain the
product in a higher yield (Runs 8 and 9). The ee became the
highest at ꢁ20 ꢂC, but the yield was low even the reaction
time was extended to 96 h (Run 10). The reaction using 30
ꢂ
mol % of catalyst at 0 C for 48 h (Run 8) is the most pref-
erable judging from the yield and ee.
CONCLUSIONS
The ee values of the product obtained by the reaction cata-
lyzed by poly(1a) were low compared with those obtained
by 1a. One possible reason for this unsatisfactory result is
the presence of intramolecular interaction between the pro-
line moieties at the side chains, which may disturb the effi-
cient coordination to the substrates.28 Therefore, we synthe-
sized the copolymers of 1a with comonomer 7, which has no
proline moiety. Table 5 summarizes the results of the aldol
reaction catalyzed by poly(1a-co-7)s. When poly(1a-co-7)s
with unit ratios of 27:73, 20:80, and 5:95 were used as cata-
lysts, the yields of 14a were higher than the cases of
poly(1a) both in CHCl3 and DMF (Runs 1, 2, and 7–12). The
ee was improved using the copolymers especially in the reac-
tions in DMF, compared with the reaction catalyzed with the
homopolymer. It was confirmed that the decrease of the pro-
line density at the side chains of the polymers was effective
to enhance asymmetric induction.29
In this study, we have demonstrated the synthesis of novel
polyphenylacetylene and polystyrene derivatives having pro-
line moieties at the side chains, and the asymmetric aldol reac-
tion of ketones with aromatic aldehydes using the polymers as
catalysts. Polyphenylacetylene derivatives adopted helical
structures with predominantly one-handed screw sense,
whereas polystyrene derivatives did not take chiral higher-
order structures. The enantioselectivities of the reactions
using the polymer catalysts were lower than those of the reac-
tions using the corresponding monomeric catalysts. The pre-
dominant chirality of the polymer catalyst-based products
inverted depending on the solvents. In the case of polypheny-
lacetylene-based catalysts, chiral interaction between the heli-
cal main chain and intermediate of the aldol reaction may
affect the enantioselectivity of the product. Use of copolymer
with an achiral monomer as catalysts was effective to enhance
ee. It is considered that a moderate density of proline moieties
is of key importance for high catalytic activity. The higher ee
values of the cyclohexanone-based aldol than those of ace-
tone-based ones are attributable to the larger stability of tran-
sition state because of the rigid cyclic structure of the ketone.
The polymer catalyst gave an anti-aldol product with 64% ee,
one of the highest-ranked values achieved by polymeric orga-
nocatalysts. We believe that an improvement of molecular
design based on this manuscript leads to a discovery of highly
selective polymeric catalysts bearing proline moieties.
Table 6 lists the results of asymmetric aldol reaction of ace-
tone with benzaldehyde and its derivatives 13b–13d in the
presence of poly(1a) as a catalyst. The product yields were
high in the order of X ¼ Cl > H > CH3. On the other hand,
no clear tendency was observed between the electronic char-
acters of the substituents and ee values of the products.
Further, the asymmetric aldol reaction of cyclohexanone and
p-nitrobenzaldehyde 13a was examined in the presence of
poly(1a) or L-proline as a catalyst (Scheme 6). Although four
isomers of 14 possibly form in this case, the ee values of the
products from cyclohexanone are commonly high compared
with those from acetone4(b),30 presumably, because the cyclic
structure of the ketone enhances the stability of the interme-
diate consisting of the ketone, aldehyde, and proline. As sum-
marized in Table 7, anti- and syn-isomers were obtained
with almost even ratios. The polymer catalyst gave anti-14
and syn-14 with lower ee values than L-proline (Runs 3 and
5) except the reaction with poly(1a) in DMF (Run 4) in
which the highest ee was achieved using the polymer cata-
lyst in this study (64%). This is one of the highest-ranked
values achieved by polymeric organocatalysts.22,23(b),23(d),23(e)
REFERENCES AND NOTES
1 (a) Daiko, P. I.; Moisan, L. Angew Chem Int Ed 2004, 43,
5138–5185; (b) Pellissier, H. Tetrahedron 2007, 63, 9267–9331;
(c) Melchiorre, P.; Marigo, M.; Carlone, A.; Bartoli, G. Angew
Chem Int Ed 2008, 47, 6138–6171; (d) Bertelsen, S.; Jorgensen,
K. A. Chem Soc Rev 2009, 38, 2178–2189; (e) Paradowska, J.;
Stodulski, M.; Mlynarski, J. Angew Chem Int Ed 2009, 48, 4288.
2 (a) List, B. Tetrahedron 2002, 58, 5573–5590; (b) Jarvo, E. R.;
Miller, S. J. Tetrahedron 2002, 58, 2481–2495; (c) Notz, W.;
Tanaka, F.; Barbas, C. F., III. Acc Chem Res 2004, 37, 580–591.
3794
WILEYONLINELIBRARY.COM/JOURNAL/JPOLA

ARTICLE
3 Movassaghi, M.; Jacobsen, E. N. Science 2002, 298,
Org Lett 2009, 11, 2968–2971; (c) Kristensen, T. E.; Vestli, K.;
Hansen, F. K.; Hansen, T. Eur J Org Chem 2009, 5185–5191; (d)
Kristensen, T. E.; Vestli, K.; Jakobsen, M. G.; Hansen, F. K.; Han-
sen, T. J Org Chem 2010, 75, 1620–1629; (e) Evans, A. C.; Lu, A.;
Ondeck, C.; Longbottom, D. A.; O’Reilly, R. K. Macromolecules
2010, 43, 6374–6380; (f) Garg, D.; Ahn, J. H.; Chauhan, G. S. J
Polym Sci Part A: Polym Chem 2010, 48, 1007–1015.
1904–1905.
4 (a) List, B.; Lerner, R. A.; Barbas, C. F., III. J Am Chem
Soc 2000, 122, 2395–2396; (b) Sakthivel, K.; Notz, W.; Bui, T.;
Barbas, C. F., III. J Am Chem Soc 2001, 123, 5260–5267.
5 (a) List, B. J Am Chem Soc 2000, 122, 9336–9337; (b) Hayashi,
Y.; Tsuboi, W.; Shoji, M.; Suzuki, N.; J Am Chem Soc 2003,
125, 11208–11209.
15 (a) Okamoto, Y.; Nakano, T. Chem Rev 1994, 94, 349–372;
(b) Cornelissen, J. J. L. M.; Rowan, A. E.; Nolte, R. J. M.; Som-
merdijk, N. A. J. M. Chem Rev 2001, 101, 4039–4070; (c)
Nakano, T.; Okamoto, Y. Chem Rev 2001, 101, 4013–4038; (d)
Yashima E.; Maeda, K.; Iida, H.; Furusho, Y.; Nagai, K. Chem
Rev 2009, 109, 6102–6211.
6 List, B.; Pojarliev, P.; Martin, H. J. Org Lett 2001, 3,
2423–2425.
7 Bui, T.; Barbas, C. F., III. Tetrahedron Lett 2000, 41,
6951–6954.
8 (a) Benaglia, M.; Puglisi, A.; Cozzi, F. Chem Rev 2003, 103,
3401; (b) Cozzi, F. Adv Synth Catal 2006, 348, 1367; (c) Corma,
A.; Garcia, H. Adv Synth Catal 2006, 348, 1391; (d) Benaglia, M.
New J Chem 2006, 30, 1525; (e) Gruttadauria, M.; Giacalone, F.;
Noto, R. Chem Soc Rev 2008, 37, 1666; (f) Itsuno, S.; Haragu-
chi, N. In Handbook of Asymmetric Heterogeneous Catalysis;
Ding, K.; Uozumi, Y., Eds.; Wiley-VCH: Weinheim, 2008; Chap-
ter 3, pp 73–129.
16 (a) Yashima, E.; Maeda, K.; Nishimura, T. Chem Eur J 2004,
10, 42–51; (b) Lam, J. W. Y.; Tang, B. Z. Acc Chem Res 2005,
38, 745–754; (c) Aoki, T.; Kaneko, T.; Teraguchi, M. Polymer
2006, 47, 4867–4892; (d) Masuda, T. J Polym Sci Part A: Polym
Chem 2007, 45, 165–180; (e) Liu, J.; Lam, J. W. Y.; Tang, B. Z.
Chem Rev 2009, 109, 5799–5867; (f) Shiotsuki, M.; Sanda, F.;
Masuda, T. Polym Chem 2011, 2, 1044–1058.
17 Tabata, M.; Yang, W.; Yokota, K. Polym
J 1990, 22,
9 (a) Miao, W.; Chan, T. H. Adv Synth Catal 2006, 348,
1711–1718; (b) Aprile, C.; Giacalone, F.; Gruttadauria, M.; Mos-
suto Marculescu, A.; Noto, R.; Revell, J. D.; Wennemers, H.
Green Chem 2007, 9, 1328–1334; (c) Zhou, L.; Wang, L. Chem
Lett 2007, 36, 628; (d) Ni, B.; Zhang, Q.; Dhugana, K.; Headley, A.
D. Org Lett 2009, 11, 1037–1040; (e) Maltsev, O. V.; Kucherenko,
A. S.; Zlotin, S. G. Eur J Org Chem 2009,5134–5137; (f) Srivas-
tava, V. Cent Eur J Chem 2010, 8, 269–272; (g) Xu, Da-Zhen.; Liu,
Y.; Shi, S.; Wang, Y. Tetrahedron Asymmetry 2010, 21,
2530–2534.
1105–1107.
18 (a) Zhao, H.; Sanda, F.; Masuda, T. Macromolecules 2004,
37, 8888–8892; (b) Zhao, H.; Sanda, F.; Masuda, T. Macromole-
cules 2004, 37, 8893–8896; (c) Zhao, H.; Sanda, F.; Masuda, T.
Polymer 2005, 46, 2841–2846.
19 (a) Zhao, H.; Sanda, F.; Masuda, T. Macromol Chem Phys
2005, 206, 1653–1658; (b) Zhao, H.; Sanda, F.; Masuda, T. J
Polym Sci Part A: Polym Chem 2005, 43, 5168–5176; (c) Sanda,
F.; Araki, H.; Masuda, T. Macromolecules 2005, 38, 10605–10608.
10 (a) Dhar, D.; Beadham, I.; Chandrasekaran, S. Proc Indian
Acad Sci Chem Sci 2003, 115, 365–372; (b) Doyaguez, E. G.; Cal-
deron, F.; Fernandez, R.; Sanchez, F.; Fernandez-Mayoralas, A. J
Org Chem 2007, 72, 9353–9356; (c) Li, P.; Wang, L.; Zhang, Y.;
Wang, G. Tetrahedron 2008, 64, 7633–7638; (d) Zhao, Y. B.;
Zhang, L. W.; Wu, L. Y.; Zhong, X.; Li, R.; Ma, J. T. Tetrahedron
Asymmetry 2008, 19, 1352–1355; (e) Zamboulis, A.; Rahier, N. J.;
Gehringer, M.; Cattoen, X.; Niel, G.; Bied, C.; Moreau, J. J. E.;
Man, M. W. C. Tetrahedron: Asymmetry 2009, 20, 2880–2885.
20 (a) Sanda, F.; Terada, K.; Masuda, T. Macromolecules 2005,
38, 8149–8154; (b) Liu, R.; Sanda, F.; Masuda, T. Polymer 2007,
48, 6510–6518.
21 (a) Sanda, F.; Teraura, T.; Masuda, T. J Polym Sci Part A:
Polym Chem 2004, 42, 4641–4647; (b) Zhao, H.; Sanda, F.;
Masuda, T. Polymer 2006, 47, 2596–2602.
22 Terada, K.; Masuda, T.; Sanda, F. J Polym Sci Part A: Polym
Chem 2009, 47, 4971–4981.
23 (a) Reggelin, M.; Doerr, S.; Klussmann, M.; Schultz, M.; Hol-
11 (a) Chouhan, G.; Wang, D.; Alper, H. Chem Commun
2007,4809–4811; (b) Gleeson, O.; Tekoriute, R.; Gun’ko, Y. K.;
Connon, S. J. Chem Eur J 2009, 15, 5669–5673.
bach, M. Proc Natl Acad Sci USA 2004, 101, 5461–5466; (b)
Muller, C. A.; Hoffart, T.; Holbach, M.; Reggelin, M. Macromole-
¨
cules 2005, 38, 5375–5380; (c) Sanda, F.; Araki, H.; Masuda, T.
Chem Lett 2005, 34, 1642–1643; (d) Maeda, K.; Tanaka, K.; Mor-
ino, K.; Yashima, E. Macromolecules 2007, 40, 6783–6785; (e)
Miyabe, T.; Hase, Y.; Iida, H.; Maeda, K.; Yashima, E. Chirality
2009, 21, 44–50; (f) Yamamoto, T.; Yamada, T.; Nagata, Y.;
Suginome, M. J Am Chem Soc 2010,7899–7901.
12 (a) Roben, C.; Stasiak, M.; Janza, B. Greiner, A.; Wendorff,
J. H.; Studer, A. Synthesis 2008,2163–2168; (b) Miao, T.; Wang,
L. Tetrahedron Lett 2008, 49, 2173–2176; (c) Liu, Y. X.; Sun, Y.
N.; Tan, H. H.; Tao, J. C. Catal Lett 2008, 120, 281–287; (d) Grut-
tadauria, M.; Salvo, A. M. P.; Giacalone, F.; Agrigento, P.; Noto,
R. Eur J Org Chem 2009,5437–5444; (e) Alza, E.; Pericas, M. A.
Adv Synth Catal 2009, 351, 3051–3056.
24 Mase, N.; Nakai, Y.; Ohara, N.; Yoda, H.; Takabe, K.;
Tanaka, F.; Barbas, C. F., III. J Am Chem Soc 2006, 128, 734–735.
13 (a) Benaglia, M.; Cinquini, M.; Cozzi, F.; Puglisi, A.; Cele-
ntano, G. Adv Synth Catal 2002, 344, 533–542; (b) Revell, J. D.;
Gantenbein, D.; Krattiger, P.; Wennemers, H. Biopolymers
2006, 84, 105–113.
25 Yashima, E.; Matsushima, T.; Okamoto, Y. J Am Chem Soc
1997, 119, 6345–6359.
26 Schrock, R. R.; Osborn, J. A. Inorg Chem 1970, 9,
2339–2343.
14 (a) Doyaguez, E. G.; Parra, F.Corrales, G.; Fernandez-Mayor-
alas, A.Gallardo, A. Polymer 2009, 50, 4438–4446; (b) Kristen-
sen, T. E.; Vestli, K.; Fredriksen, K. A.; Hansen, F. K.; Hansen, T.
27 Rodr´ıguez-Llansola, F.; Escuder, B.; Miravet, J. F. Org Bio-
mol Chem 2009, 7, 3091–3094.
SYNTHESIS OF POLYMERS AND THEIR APPLICATION, IKEDA ET AL.
3795

JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
28 Another possibility is racemization and/or epimerization
during monomer synthesis, polymerization, and deprotection.
Although this possibility is undeniable, the degrees seem to be
small, because the reagents used for monomer synthesis and
deprotection are common ones for peptide synthesis, and the
polymerization was carried out under neutral conditions. We
did not check the concrete data of racemization/epimerization
because of difficult determination.
tion of a chair-like transition state for the aldol reaction of ace-
tone with p-nitrobenzaldehyde, which is reported in ref. 5a.
Whereas in the case of copolymer [poly(1a-co-7)], the intramo-
lecular interaction between the proline moieties is smaller than
that of the homopolymer. Therefore, it seems that the chair-
like transition state forms more efficiently because of the low
density of 1a. As the result, the ee of the aldol increases as 1a
unit ratio is decreased. On the other hand, the positive concen-
tration effect on the ee (Table 4) is explainable from the view-
point of collisional frequency between the proline moieties and
substrates (acetone and p-nitrobenzaldehyde).
29 A relative lower density of 1a in the copolymers [poly(1a-
co-7)s] was suitable for deriving higher yields and ee values as
summarized in Table 5. In the case of homopolymer [poly(1a)],
it is likely that the proline moieties intramolecularly interact
each other at the side chains, leading to disturbance of forma-
30 Bahmanyar, S.; Houk, K. N.; Martin, H. J.; List, B. J Am
Chem Soc 2003, 125, 2475–2479.
3796
WILEYONLINELIBRARY.COM/JOURNAL/JPOLA