ARTICLE
solvent was removed under reduced pressure, and the resi-
due was purified by flash chromatography on silica gel (ethyl
acetate/hexane ¼ 7/1) to give 2.6 g of 1a as an orange vis-
cous oil (67%).
3.40 (s, 3 H), 3.38 (t, J ¼ 5.3 Hz, 2 H). 13C NMR (126 MHz,
CDCl3, d, ppm): 165.3, 152.6, 151.3, 132.2, 129.3, 125.4,
121.9, 117.4, 111.7, 72.0, 70.6, 70.4, 69.2, 59.0, 42.9. IR
(neat, cmꢀ1): 3369, 2876, 1704, 1607, 1278, 1109, 771.
1H NMR (500 MHz, CDCl3, d, ppm): 7.86 (d, J ¼ 8.9 Hz, 2 H),
6.57 (d, J ¼ 8.9 Hz, 2 H), 4.69 (br s, 1 H), 3.84 (s, 3 H), 3.71
(t, J ¼ 5.2 Hz, 2 H), 3.67–3.65 (m, 6 H), 3.57–3.55 (m, 2 H),
3.39 (s, 3 H), 3.35 (q, J ¼ 4.6 Hz, 2 H). 13C NMR (126 MHz,
CDCl3, d, ppm): 167.2, 152.0, 131.4, 118.1, 115.5, 71.8, 70.4,
70.2, 69.1, 61.8, 58.9, 51.4, 42.8. IR (neat, cmꢀ1): 3369,
2876, 1704, 1607, 1278, 1109, 771.
Polymerization
Polymerization of 1b
A round-bottomed flask equipped with a three-way stopcock
was purged with argon and then charged with dry THF
(0.5 mL) and 1.0 M LiHMDS in ꢁTHF (0.50 mL, 0.50 mmol).
The solution was cooled to ꢀ20 C with stirring under an ar-
gon atmosphere. A solution of 1b (0.180 g, 0.50 mmol) and
3 (0.0053 g, 0.025 mmol) in dry THF (0.5 mL) at ꢀ20 ꢁC
was added at once with a syringe into the flask containing
LiHMDS through the three-way stopcock under a stream of
Synthesis of 4-{2-[2-(2-Methoxyethoxy)ethoxy]acetylamino}
benzoic Acid Phenyl Ester (4b)
A mixture of 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (8.0
mL, 52 mmol), phenyl 4-aminobenzoate (8.6 g, 40 mmol),
and DMAP (6.4 g, 52 mmol) in dry CH2Cl2 (180 mL) was
stirred at 0 ꢁC for 10 min. Into the flask was added EDCI
ꢁ
dry nitrogen. Stirring was continued at ꢀ20 C for 4 h, then
the reaction was quenched with saturated aqueous NH4Cl,
and the whole was extracted with CH2Cl2. The organic layer
was washed with water and dried over anhydrous MgSO4.
Concentration in vacuo gave a crude product, whose Mn and
ꢁ
(10.0 g, 52 mmol) with stirring at 0 C. The reaction mixture
was stirred at room temperature for 48 h, and then the reac-
tion was quenched with water, followed by extraction with
CH2Cl2. The combined organic layer was washed with 1 M
HCl and saturated aqueous NaHCO3, and dried over anhy-
drous MgSO4. The solvent was removed under reduced pres-
sure, and the residue was purified by flash chromatography
on silica gel (ethyl acetate/hexane ¼ 2/1) to give 12.8 g of
4b as a pale yellow viscous oil (83%).
Mw/Mn were determined by GPC (Mn ¼ 4000, Mw/Mn
¼
1.15). The residue was purified by preparative HPLC to give
0.063 g of poly1b as a yellow viscous oil (46%).
Poly1b: Mn ¼ 6400 (determined by 1H NMR), Mn (calcd.) ¼
5500, Mw/Mn ¼ 1.15.
1H NMR (600 MHz, CDCl3, d, ppm): 7.08 (d, J ¼ 7.2 Hz, 2n
H), 6.89 (d, J ¼ 7.9 Hz, 2n H), 4.15–3.88 (m, 2n H), 3.79–
3.46 (m, 10n H), 3.39–3.30 (m, 3n H). IR (neat, cmꢀ1): 3059,
2873, 1644, 1603, 1509, 1107, 849.
1H NMR (600 MHz, CDCl3, d, ppm): 9.05 (br s, 1 H), 8.17 (d,
J ¼ 8.9 Hz, 2 H), 7.81 (d, J ¼ 8.9 Hz, 2 H), 7.42 (t, J ¼ 7.4
Hz, 2 H), 7.23 (t, J ¼ 7.5 Hz, 1 H), 7.21 (d, J ¼ 7.7 Hz, 2 H),
4.12 (s, 2 H), 3.80–3.78 (m, 2 H), 3.75–3.73 (m, 4 H), 3.61–
3.59 (m, 2 H), 3.38 (s, 3 H). IR (neat, cmꢀ1): 3332, 2882,
1719, 1282, 1176, 1109, 858.
Synthesis of Block Copolymer
A round-bottomed flask equipped with a three-way stopcock
was purged with argon and then charged with dry THF (0.5
mL) and 1.0 M LiHMDS in THF (0.50 mL, 0.50 mmol). The
ꢁ
solution was cooled to ꢀ20 C with stirring under an argon
Synthesis of 4-{2-[2-(2-Methoxyethoxy)ethoxy]ethylamino}-
benzoic Acid Phenyl Ester (1b)
atmosphere. A solution of 1b (0.180 g, 0.50 mmol) ꢁand 3
(0.0053 g, 0.025 mmol) in dry THF (0.5 mL) at ꢀ20 C was
added at once with a syringe into the flask containing
LiHMDS through the three-way stopcock under a stream
of dry nitrogen. After having been stiꢁrred for 10 min at
A three-necked flask, equipped with a dropping funnel, a
reflux condenser, and a gas inlet tube, was purged with ar-
gon and then charged with 0.98 M borane-THF complex in
THF (40 mL, 39 mmol). The solution was cooled to 0 ꢁC
under an argon atmosphere with stirring for 10 min. A solu-
tion of 4b (11.6 g, 30 mmol) in dry THF (50 mL) was added
dropwise from the dropping funnel, and the mixture was
refluxed for 3 h. It was then cooled to room temperature,
6 M HCl (5 mL) was added to it, and the whole was heated
under reflux for 1 h. The solution was diluted with water
and neutralized to approximately pH 8 with NaHCO3, then
extracted with CH2Cl2. The combined organic layer was
washed with water and dried over anhydrous MgSO4. The
solvent was removed under reduced pressure, and the resi-
due was purified by flash chromatography on silica gel (ethyl
acetate/hexane ¼ 3/4) to give 4.6 g of 1b as an orange oil
(43%).
ꢁ
ꢀ20 C, the mixture was cooled to ꢀ50 C with stirring. Stir-
ꢁ
ring was continued at ꢀ50 C for 6 h, then 0.1 mL of the so-
lution was withdrawn and quenched with saturated aqueous
NH4Cl to measure the Mn value and Mw/Mn ratio of poly1b
[Mn (GPC) ¼ 3600, Mw/Mn ¼ 1.11]. Immediately after the
sampling, the reaction mixture was warmed to ꢀ10 ꢁC, and
then 1.0 M LiHMDS in THF (0.50 mL, 0.50 mmol) at room
temperature was slowly added, followed by fast addition of a
solution of 2 (0.123 g, 0.47 mmol) in dry THF (1.0 mL) at
ꢀ10 ꢁC. The mixture was stirred at ꢀ10 ꢁC for 15 h. The
reaction was quenched with saturated aqueous NH4Cl, and
the whole was extracted with CHCl3. The organic layer was
washed with water and dried over anhydrous MgSO4. Con-
centration in vacuo gave a crude product, whose Mn and
1H NMR (600 MHz, CDCl3, d, ppm): 8.01 (d, J ¼ 8.6 Hz, 2 H),
7.40 (t, J ¼ 8.1 Hz, 2 H), 7.23 (t, J ¼ 7.4 Hz, 1 H), 7.19 (d, J
¼ 8.4 Hz, 2 H), 6.63 (d, J ¼ 8.6 Hz, 2 H), 4.80 (s, 1 H), 3.74
(t, J ¼ 5.2 Hz, 2 H), 3.71–3.65 (m, 6 H), 3.59–3.56 (m, 2 H),
Mw/Mn were determined by GPC (Mn ¼ 6700, Mw/Mn ¼
1.15). The residue was purified by preparative HPLC to give
0.188 g of the block copolymer of poly1b and poly2 as a yel-
low viscous oil (75%).
CHAIN-GROWTH CONDENSATION POLYMERIZATION, YOSHINO ET AL.
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