Supporting Information
Chain-Growth Condensation Polymerization Approach to Synthesis of WellDefined Polybenzoxazole: Importance of Higher Reactivity of 3-Amino-4Hydroxybenzoic Acid Ester Compared to 4-Amino-3-Hydroxybenzoic Acid Ester
Yoshihiro Ohta,1 Tetsurou Niiyama,1 Akihiro Yokoyama,2 Tsutomu Yokozawa1
1
Department of Material and Life Chemistry, Kanagawa University, Rokkakubashi, Kanagawa-ku,
Yokohama 221-8686, Japan
2
Present address: Department of Material and Life Science, Seikei University, Kichijoji-Kitamachi,
Musashino-shi, Tokyo 180-8633, Japan
1
Synthesis of monomer 1a
Scheme S1. Synthesis of 1a.
Synthesis of phenyl 3-methoxy-4-nitrobenzoate 6
To a solution of 3-methoxy-4-nitrobenzoic acid (8.99 g, 45.7 mol), 4-(dimethylamino)pyridine
(DMAP) (6.71 g, 54.9 mmol), and phenol (5.23 g, 55.6 mmol) in dry DMF (100 mL) was added 1-ethyl-3(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCI) (11.4 g, 59.5 mmol) at 0 oC. The mixture was
stirred for 18 h, and then the reaction was quenched with water. The whole was extracted with CH2Cl2.
The combined organic layers were washed with 1 M HCl, sat. NaHCO3, and water, dried over anhydrous
MgSO4, and concentrated under reduced pressure. The residue was recrystallized from ethyl acetatehexane to give 6 as a light yellow solid (6.47 g, 52%). mp: 126.0-126.5 oC.
H NMR (600 MHz, CDCl3, , ppm): 7.91 (d, J = 6.9 Hz, 1 H), 7.90 (d, J = 1.0 Hz, 1 H), 7.89 (dd, J = 8.5 and
1
1.4 Hz, 1 H), 7.46 (t, J = 7.9 Hz, 2 H), 7.32 (t, J = 7.5 Hz, 1 H), 7.22 (d, J = 7.9 Hz, 2 H), 4.05 (s, 3 H). 13C
NMR (150 MHz, CDCl3, , ppm): 163.4, 152.5, 150.5, 142.8, 134.3, 129.7, 126.4, 125.4, 122.0, 121.4,
115.1, 56.8. IR (KBr): 3280, 1733, 1542, 901, 850, 741, 696 cm-1.
2
Synthesis of phenyl 4-amino-3-methoxybenzoate 7
5% Pd/C (0.45 g) was added to a solution of phenyl 3-methoxy-4-nitrobenzoate (6) (6.05 g, 22.2
mol) in ethyl acetate (300 mL). The flask containing the reaction mixture was degassed and then charged
with hydrogen. The mixture was stirred at room temperature for 7.5 h, and then filtrated through
Celite®. The filtrate was concentrated under reduced pressure to give 7 as a white solid (5.34 g, 99%).
mp: 95.5-96.5 oC.
H NMR (600 MHz, CDCl3, , ppm): 7.73 (dd, J = 7.1 and 1.8 Hz, 1 H), 7.58 (d, J = 1.7 Hz, 1 H), 7.41 (t, J =
1
7.6 Hz, 2 H), 7.25 (t, J = 7.6 Hz, 1 H), 7.20 (d, J = 7.5 Hz, 2 H), 6.72 (d, J = 7.8 Hz, 1 H), 4.30 (br s, 2 H), 3.93
(s, 3 H). 13C NMR (150 MHz, CDCl3, , ppm): 165.4, 151.2, 146.1, 141.8, 129.3, 125.5, 124.9, 121.9, 118.4,
113.0, 111.5, 55.6. IR (KBr): 3477, 3369, 2832, 1706, 1590, 1519, 900, 869, 743, 690 cm -1.
Synthesis of phenyl 3-methoxy-4-(octylamino)benzoate 1a
Sodium triacetoxyborohydride (2.80 g, 13.2 mmol) was added to a solution of phenyl 4-amino-3methoxybenzoate (7) (2.40 g, 9.86 mol) and octanal (1.5 mL, 9.6 mmol) in dry THF (100 mL) at room
temperature. The mixture was stirred for 9 h, and then the reaction was quenched with sat. NaHCO3.
The whole was extracted with CH2Cl2. The combined organic layers were washed with water, dried over
MgSO4, and concentrated under reduced pressure. The residue was purified by flash chromatograph on
silica gel (hexane/ethyl acetate = 15/1), and then the product was recrystallized from ethanol to give 1a
as a white solid (1.60 g, 51%). mp: 49.5-50.0 oC.
3
H NMR (600 MHz, CDCl3, , ppm): 7.81 (dd, J = 8.2 and 1.0 Hz, 1 H), 7.51 (d, J = 1.7 Hz, 1 H), 7.40 (t, J =
1
7.9 Hz, 2 H), 7.23 (t, J = 6.9 Hz, 1 H), 7.19 (d, J = 7.5 Hz, 2 H), 6.57 (d, J = 8.6 Hz, 1 H), 4.81-4.75 (br s, 1 H),
3.90 (s, 3 H), 3.20 (q, J = 7.1 Hz, 2 H), 1.67 (quint, J = 7.3 Hz, 2 H), 1.41 (quint, J = 7.2 Hz, 2 H), 1.38-1.25
(m, 8 H), 0.89 (t, J = 7.0 Hz, 3 H). 13C NMR (125 MHz, CDCl3, , ppm): 165.5, 151.3, 145.5, 143.2, 129.2,
125.6, 125.3, 121.9, 115.7, 110.0, 107.6, 55.5, 43.0, 31.8, 29.3, 29.2, 27.1, 22.6, 14.0. IR (KBr): 3423,
2956, 2920, 2856, 1716, 1603, 1490, 886, 815, 742, 692 cm -1.
Synthesis of monomer 1b
Scheme S2. Synthesis of 1b.
Synthesis of phenyl 3-hydroxy-4-nitrobenzoate 8
EDCI (6.17 g, 32.2 mmol) was added to a solution of 3-hydrox-4-nitrobenzoic acid (5.04 g, 27.3
mol), DMAP (4.77 g, 39.0 mmol), and phenol (13.6 g, 143 mmol) in dry DMF (50 mL) at 0 oC. The mixture
was stirred for 13 days, and then the reaction was quenched with water. The whole was extracted with
CH2Cl2. The combined organic layers were washed with 1 M HCl, sat. NaHCO3, and water, dried over
4
anhydrous MgSO4, and concentrated in vacuo. The residue was purified by recrystallization from ethyl
acetate-hexane to give 6 as a light yellow solid (5.47 g, 77%). mp: 143.5-144.5 oC.
H NMR (600 MHz, CDCl3, , ppm): 10.55 (s, 1 H), 8.25 (d, J = 9.0 Hz, 1 H), 8.01 (d, J = 1.7 Hz, 1 H), 7.78
1
(dd, J = 8.8 and 1.7 Hz, 1 H), 7.46 (t, J = 7.8 Hz, 2 H), 7.32 (t, J = 7.6 Hz, 1 H), 7.22 (d, J = 8.8 Hz, 2 H). 13C
NMR (150 MHz, CDCl3, , ppm): 162.9, 154.7, 150.4, 137.4, 136.1, 129.6, 126.4, 125.4, 122.2, 121.3,
121.0. IR (KBr): 3280, 1733, 1542, 901, 850, 741, 696 cm-1.
Synthesis of phenyl 3-{(2-methoxyethoxy)methoxy}-4-nitrobenzoate 9
60% NaH in mineral oil (0.848 g, 21.2 mmol) was placed in a flask, washed with dry hexane three
times, and dried under reduced pressure. A solution of phenyl 3-hydrox-4-nitrobenzoate (8) (4.99 g, 19.3
mmol) and 2-methoxyethoxymethyl chloride (2.65 mL, 23.4 mmol) in dry THF (150 mL) was added to the
flask including NaH at 0 oC. The mixture was stirred at 0 oC for 10 min and at ambient temperature for 18
h. Unreacted NaH was quenched with a small amount of methanol, and then the reaction mixture was
poured into water. The mixture was extracted with CH2Cl2. The combined organic layers were washed
with sat. NaHCO3, dried over anhydrous MgSO4, and concentrated under reduced pressure. The residue
was purified by flash chromatography on silica gel (hexane/ethyl acetate = 3/1) to give 9 as a brown
liquid (5.86 g, 88%).
H NMR (600 MHz, CDCl3, , ppm): 8.16 (d, J = 1.7 Hz, 1 H), 7.93 (dd, J = 8.5 and 1.6 Hz, 1 H), 7.86 (d, J =
1
8.3 Hz, 1 H), 7.45 (t, J = 8.4 Hz, 2 H), 7.31 (t, J = 7.6 Hz, 1 H), 7.21 (d, J = 8.1 Hz, 2 H), 5.47 (s, 2 H), 3.923.89 (m, 2 H), 3.60-3.56 (m, 2 H), 3.37 (s, 3 H). 13C NMR (150 MHz, CDCl3, , ppm): 163.2, 150.5, 149.9,
143.9, 134.2, 129.6, 126.3, 125.0, 123.3, 121.4, 118.9, 94.4, 71.3, 68.7, 59.0; IR (neat): 3057, 2926, 2885,
2820, 1741, 1608, 1591, 1531, 1216, 1193, 845, 800, 743, 691cm -1.
5
Synthesis of phenyl 4-amino-3-{(2-methoxyethoxy)methoxy}benzoate 10
Into a solution of phenyl 3-{2-methoxyethyoxy}methoxy}-4-nitrobenzoate (9) (5.51 g, 15.1 mmol) in
ethyl acetate (150 mL) was added 5% Pd/C (0.276 g) at room temperature. The flask containing reaction
mixture was degassed and charged with hydrogen. The mixture was stirred at ambient temperature for
3.5 h, and filtrated through Celite®. The filtrate was concentrated under reduced pressure. The residue
was purified by flash chromatography on silica gel (hexane/ether = 1/1) to give 10 as a white solid (4.78
g, 95%). mp: 87.5-88.0 oC.
H NMR (600 MHz, CDCl3, , ppm): 7.83 (d, J = 1.7 Hz, 1 H), 7.76 (dd, J = 7.5 and 1.7 Hz, 1 H), 7.41 (t, J =
1
7.5 Hz, 2 H), 7.24 (t, J = 7.4 Hz, 1 H), 7.18 (d, J = 8.6 Hz, 2 H), 6.75 (d, J = 8.3 Hz, 1 H), 5.36 (s, 2 H), 4.404.20 (br s, 2 H), 3.88-3,85 (m, 2 H), 3.61-3.57 (m, 2 H), 3.39 (s, 3 H). 13C NMR (125 MHz, CDCl3, , ppm):
165.1, 151.2, 143.5, 142.6, 129.3, 126.2, 125.5, 121.9, 118.6, 116.4, 113.7, 94.4, 71.6, 68.2, 59.1. IR
(KBr): 3462, 3355, 2927, 1712, 1629, 1592, 1258, 1190, 879, 846, 741, 691 cm -1.
Synthesis of phenyl 3-hydrox-4-(octylamino)benzoate 1b
Glacial acetic acid (0.30 mL, 3.5 mmol) was added to a solution of phenyl 4-amino-3-{2(methoxyethoxy)methoxy}benzoate (10) (1.04 g, 3.28 mmol), octanal (0.50 mL, 3.2 mmol), and sodium
triacetoxyborohydride (1.04 g, 4.92 mmol) in dry THF (10 mL) at room temperature. The mixture was
stirred for 18 h, and then the reaction was quenched with sat. NaHCO3. The whole was extracted with
CH2Cl2. The combined organic layers were washed with water, dried over MgSO4, and concentrated
6
under reduced pressure. The residue was purified by flash chromatograph on silica gel (hexane/ethyl
acetate = 4/1) to give 1b as a yellow viscous liquid (0.715 g, 53%).
H NMR (600 MHz, CDCl3, , ppm): 7.84 (dd, J = 7.8 and 1.9 Hz, 1 H), 7.77 (d, J = 1.7 Hz, 1 H), 7.40 (t, J =
1
7.6 Hz, 2 H), 7.23 (t, J = 7.4 Hz, 1 H), 7.18 (d, J = 7.9 Hz, 2 H), 6.61 (d, J = 8.6 Hz, 1 H), 5.35 (s, 2 H), 4.84 (br
s, 1 H), 3.87-3.83 (m, 2 H), 3.60-3.55 (m, 2 H), 3.39 (s, 3 H), 3.21 (t, J = 7.3 Hz, 2 H), 1.68 (quint, J = 7.2 Hz,
2 H), 1.42 (quint, J = 7.4 Hz, 2 H), 1.38-1.24 (m, 8 H), 0.89 (t, J = 6.8 Hz, 3 H). 13C NMR (125 MHz, CDCl3, ,
ppm): 165.2, 151.2, 143.7, 143.0, 129.1, 126.6, 125.2, 121.8, 115.8, 114.8, 108.1, 94.3, 71.5, 68.1, 58.9,
42.9, 31.7, 29.2, 29.1, 27.0, 22.5, 14.0. IR (neat): 3410, 2963, 2923, 2852, 1736, 1686, 1535, 1342, 1100,
1030, 802, 711 cm-1.
Synthesis of monomer 3a
Scheme S3. Synthesis of 3a.
7
Synthesis of methyl 4-{(2-methoxyethoxy)methoxy}-3-nitrobenzoate 13
55% NaH in mineral oil (1.30 g, 29.8 mmol) was placed in a flask, washed with dry hexane three
times, and dried under reduced pressure. A solution of methyl 4-hydroxy-3-nitrobenzoate (5.00 g, 25.4
mmol) in dry THF (40 mL) and a solution of 2-methoxyethoxymethyl chloride (3.50 mL, 30.9 mmol) in dry
THF (40 mL) were added to the flask including NaH at 0 oC. The mixture was stirred at 0 oC for 1 h and at
room temperaturefor 7 h. Unreacted NaH was quenched with a small amount of methanol, and then the
reaction mixture was poured into water. The mixture was extracted with CH2Cl2. The combined organic
layers were washed with sat. NaHCO3, dried over anhydrous MgSO4, and concentrated under reduced
pressure. The residue was purified by flash chromatography on silica gel (hexane/CH2Cl2 = 4/1) to give 13
as a brown liquid (4.30 g, 59%).
H NMR (600 MHz, CDCl3, , ppm): 8.46 (d, J = 1.7 Hz, 1 H), 8.18 (dd, J = 8.5 and 1.6 Hz, 1 H), 7.42 (d, J =
1
8.3 Hz, 1 H), 5.47 (s, 2 H), 3.94 (s, 3 H), 3.92-3.89 (m, 2 H), 3.60-3.56 (m, 2 H), 3.36 (s, 3 H). 13C NMR (150
MHz, CDCl3, , ppm): 164.7, 153.5, 140.0, 134.8, 126.8, 123.5, 116.3, 93.9, 71.2, 68.7, 58.9, 52.4; IR
(neat): 2928, 2821, 1725, 1618, 1576, 1536, 1500, 1198, 1193, 844, 783, 762, 713, 679 cm -1.
Synthesis of methyl 3-amino-4-{(2-methoxyethoxy)methoxy}benzoate 14
Into a solution of methyl 4-{(2-methoxyethoxy)methoxy}benzoate (13) (2.92 g, 10.2 mmol) in
ethyl acetate (30 mL) was added 5% Pd/C (0.202 g). The flask containing the reaction mixture was
degassed and charged with hydrogen. The mixture was stirred at room temperature for 2 h, and then
filtrated through Celite®. The filtrate was concentrated under reduced pressure, and the residue was
purified by flash chromatography on silica gel (hexane/ethyl acetate = 1/1) to give 13 as a light yellow
viscous liquid (2.61 g, 99%).
8
H NMR (600 MHz, CDCl3, , ppm): 7.42 (dd, J = 8.3 and 2.0 Hz, 1 H), 7.40 (d, J = 2.0 Hz, 1 H), 7.07 (d, J =
1
8.3 Hz, 1 H), 5.35 (s, 2 H), 3.95 (br s, 2 H), 3.86 (s, 3 H), 3.85-3,82 (m, 2 H), 3.57-3.54 (m, 2 H), 3.37 (s, 3 H).
C NMR (125 MHz, CDCl3, , ppm): 167.0, 140.3, 136.3, 123.9, 120.6, 116.0, 113.3, 93.7, 71.5, 68.0, 58.9,
13
51.8; IR (KBr): 3487, 3369, 2925, 1711, 1618, 1595, 1253, 1208, 848, 765, 691 cm -1.
Synthesis of methyl 4-{(2-methoxyethoxy)methoxy}-3-(octylamino)benzoate 3a
A solution of octanal (0.964 g, 7.52 mmol) in distilled 1,2-dichloroethane (5.0 mL) and sodium
triacetoxyborohydride (1.75 g, 8.26 mmol) were successively added to a solution of methyl 3-amino-4{(2-methoxyethoxy)methoxy}benzoate (14) (1.92 g, 7.52 mmol) in distilled 1,2-dichloroethane (15.0 mL).
The mixture was stirred at room temperature for 4 h, and then the reaction was quenched with sat.
NaHCO3. The whole was extracted with CH2Cl2. The combined organic layers were washed with water,
dried over anhydrous MgSO4, and concentrated under reduced pressure. The residue was purified by
flash chromatography on silica gel (hexane/ethyl acetate = 5/1) to give 3a as a yellow viscous liquid (1.16
g, 42%).
H NMR (600 MHz, CDCl3, , ppm): 7.36 (dd, J = 8.2 and 2.1 Hz, 1 H), 7.25 (d, J = 2.1 Hz, 1 H), 7.04 (d, J =
1
8.6 Hz, 1 H), 5.35 (s, 2 H), 4.20 (br s, 1 H), 3.87 (s, 3 H), 3.84-3.81 (m, 2 H), 3.58-3.55 (m, 2 H), 3.38 (s, 3 H),
3.16 (t, J = 7.0 Hz, 2 H), 1.67 (quint, J = 7.4 Hz, 2 H), 1.42 (quint, J = 7.2 Hz, 2 H), 1.38-1.22 (m, 8 H), 0.88
(t, J = 7.0 Hz, 3 H). 13C NMR (125 MHz, CDCl3, , ppm): 167.5, 147.8, 138.5, 124.1, 118.7, 112.3, 110.7,
93.8, 71.6, 68.0, 59.0, 51.8, 43.6, 31.8, 29.39, 29.37, 29.2, 27.2, 22.6, 14.1. IR (neat): 3431, 2926, 2855,
1721, 1603, 1535, 1492, 1405, 1363, 1278, 1103, 1024, 900, 814, 756, 740, 689 cm -1.
9
Synthesis of monomer 3b
Scheme S4. Synthesis of 3b.
Synthesis of phenyl 4-hydroxy-3-nitrobenzoate 15
EDCI (22.73 g, 0.119 mol) was added to a solution of 4-hydrox-3-nitrobenzoic acid (20.03 g,
0.109 mol), DMAP (18.73 g, 0.153 mol), and phenol (51.17 g, 0.544 mol) in dry DMF (1.0 L)at 0 oC. The
mixture was stirred at ambient temperature for 24 h, and then the reaction was quenched with water.
The whole was extracted with CH2Cl2. The combined organic layers were washed with 1 M HCl, sat.
NaHCO3, and water, dried over anhydrous MgSO4, and concentrated under reduced pressure. The
residue was recrystallized from ethyl acetate-hexane to give 15 as a light yellow solid (15.51 g, 55%).
mp: 143.5-144.5 oC.
H NMR (500 MHz, CDCl3, , ppm): 10.97 (s, 1 H), 9.00 (d, J = 2.3 Hz, 1 H), 8.38 (dd, J = 8.9 and 2.3 Hz, 1
1
H), 7.44 (t, J = 7.5 Hz, 2 H), 7.32-7.28 (m, 2 H), 7.21 (d, J = 8.6 Hz, 2 H). 13C NMR (150 MHz, CDCl3, ,
10
ppm): 162.9, 158.5, 150.5, 138.3, 133.3, 129.6, 127.9, 126.2, 122.1, 121.5, 120.5. IR (KBr): 3280, 1733,
1542, 901, 850, 741, 696 cm-1.
Synthesis of phenyl 4-{(2-methoxyethoxy)methoxy}-3-nitrobenzoate 16
55% NaH in mineral oil (0.261 g, 5.98 mmol) was placed in a flask, washed with dry hexane three
times, and dried under reduced pressure. A solution of phenyl 4-hydrox-3-nitrobenzoate (15) (1.526 g,
5.89 mmol) and 2-methoxyethoxymethyl chloride (0.80 mL, 7.3 mmol) in dry THF (20 mL) was added to
the flask including NaH at 0 oC. The mixture was stirred at 0 oC for 10 min and at room temperature for 7
h. Unreacted NaH was quenched with a small amount of methanol, and then the reaction mixture was
poured into water. The mixture was extracted with CH2Cl2. The combined organic layers were washed
with sat. NaHCO3, dried over anhydrous MgSO4, and concentrated in vacuo. The residue was purified by
flash chromatography on silica gel (hexane/CH2Cl2 = 1/5) to give 16 as a brown liquid (1.112 g, 54%).
H NMR (600 MHz, CDCl3, , ppm): 8.16 (d, J = 1.7 Hz, 1 H), 7.93 (dd, J = 8.5 and 1.6 Hz, 1 H), 7.86 (d, J =
1
8.3 Hz, 1 H), 7.45 (t, J = 8.4 Hz, 2 H), 7.31 (t, J = 7.6 Hz, 1 H), 7.21 (d, J = 8.1 Hz, 2 H), 5.47 (s, 2 H), 3.923.89 (m, 2 H), 3.60-3.56 (m, 2 H), 3.37 (s, 3 H). 13C NMR (150 MHz, CDCl3, , ppm): 162.9, 153.9, 150.5,
140.2, 135.3, 129.5, 127.3, 126.1, 122.8, 121.4, 116.6, 94.0, 71.2, 68.2, 58.9. IR (neat): 3057, 2926, 2885,
2820, 1741, 1608, 1591, 1531, 1216, 1193, 845, 800, 743, 691 cm-1.
Synthesis of phenyl 3-amino-4-{(2-methoxyethoxy)methoxy}benzoate 17
Into a solution of phenyl 4-{(2-methoxyethoxy)methoxy}benzoate (16) (1.00 g, 2.88 mmol) in
ethyl acetate (30 mL) was added 5% Pd/C (0.051 g). The flask containing the reaction mixture was
11
degassed and charged with hydrogen. The mixture was stirred at room temperature for 5 h, and then
filtrated through Celite®. The filtrate was concentrated under reduced pressure. The residue was
purified by flash chromatography on silica gel (hexane/ethyl acetate = 1/1) to give 17 as a yellow viscous
liquid (0.765 g, 84%).
H NMR (600 MHz, CDCl3, , ppm): 7.60 (dd, J = 8.3 and 2.0 Hz, 1 H), 7.54 (d, J = 2.0 Hz, 1 H), 7.41 (t, J =
1
7.6 Hz, 2 H), 7.25 (t, J = 7.4 Hz, 1 H), 7.19 (d, J = 8.6 Hz, 2 H), 7.14 (d, J = 8.3 Hz, 1 H), 5.36 (s, 2 H), 3.95 (br
s, 2 H), 3.87-3,83(m, 2 H), 3.60-3.55(m, 2 H), 3.39 (s, 3 H). 13C NMR (125 MHz, CDCl3, , ppm): 165.1,
151.1, 148.8, 136.6, 129.4, 125.6, 123.2, 121.7, 121.5, 116.5, 113.4, 93.7, 71.5, 68.1, 59.1. IR (KBr): 3462,
3355, 2927, 1712, 1629, 1592, 1258, 1190, 879, 846, 741, 691 cm-1.
Synthesis of phenyl 4-{(2-methoxyethoxy)methoxy}-3-(octylamino)benzoate 3b
A solution of octanal (0.309 g, 2.41 mmol) in dist. 1,2-dichloroethane (2.0 mL) and sodium
triacetoxyborohydride (0.609 g, 2.74 mmol) were successively added to a solution of phenyl 3-amino-4{(2-methoxyethoxy)methoxy}benzoate (17) (0.765 g, 2.41 mmol) in dist. 1,2-dichloroethane (8.0 mL).
The mixture was stirred at room temperature for 5 h, and then the reaction was quenched with sat.
NaHCO3. The whole was extracted with CH2Cl2. The combined organic layers were washed with water,
dried over anhydrous MgSO4, and concentrated in vacuo. The residue was purified by flash
chromatography on silica gel (hexane/CH2Cl2 = 3/1) to give 3b as a yellow viscous liquid (0.398 g, 39%).
H NMR (500 MHz, CDCl3, , ppm): 7.54 (dd, J = 8.2 and 2.1 Hz, 1 H), 7.41 (t, J = 8.1 Hz, 2 H), 7.38 (d, J =
1
2.1 Hz, 1 H), 7.25 (t, J = 7.4 Hz, 1 H), 7.20 (d, J = 8.6 Hz, 2 H), 7.11 (d, J = 8.6 Hz, 1 H), 5.38 (s, 2 H), 4.26 (br
s, 2 H), 3.87-3.81 (m, 2 H), 3.60-3.54 (m, 2 H), 3.39 (s, 3 H), 3.19 (t, J = 7.0 Hz, 2 H), 1.68 (quint, J = 7.4 Hz,
2 H), 1.43 (quint, J = 7.2 Hz, 2 H), 1.38-1.22 (m, 8 H), 0.88 (t, J = 7.0 Hz, 3 H). 13C NMR (150 MHz, CDCl3, ,
12
ppm): 165.6, 151.2, 148.3, 138.7, 129.3, 125.6, 123.4, 121.8, 119.5, 112.3, 111.0, 93.7, 71.5, 68.0, 59.1,
43.6, 31.8, 29.4, 29.2, 27.2, 22.6, 14.1. IR (neat): 3431, 2926, 2855, 1721, 1603, 1535, 1492, 1405, 1363,
1278, 1103, 1024, 900, 814, 756, 740, 689 cm-1.
Synthesis of monomer 3c
Scheme S5. Synthesis of 3c.
Synthesis of phenyl 4-{(2-methoxyethoxy)methoxy}-3-{(4-octyloxybenzyl)amino}benzoate 3c
A solution of 4-(octyloxy)benzaldehyde (2.68 g, 11.4 mmol) in dist. 1,2-dichloroethane (5.0 mL)
and sodium triacetoxyborohydride (2.66 g, 12.6 mmol) were successively added to a solution of phenyl
3-amino-4-{(2-methoxyethoxy)methoxy}benzoate (17) (3.63 g, 11.4 mmol) in dist. 1,2-dichloroethane
(15.0 mL). The mixture was stirred at ambient temperature for 5 h, and then the reaction was quenched
with sat. NaHCO3. The whole was extracted with CH2Cl2. The combined organic layers were washed with
water, dried over anhydrous MgSO4, and concentrated under reduced pressure. The residue was
purified by flash chromatography on silica gel (hexane/ethyl acetate = 3/1) to give 3c as a colorless
viscous liquid (4.00 g, 65%).
13
H NMR (600 MHz, CDCl3, , ppm): 7.57 (d, J = 8.6 Hz, 1 H), 7.45 (s, 1 H), 7.40 (t, J = 8.6 Hz, 2 H), 7.30 (d, J
1
= 8.2 Hz, 2 H), 7.24 (t, J = 7.5 Hz, 1 H), 7.19 (d, J = 8.6 Hz, 2 H), 7.13 (d, J = 8.6 Hz, 1 H), 6.88 (d, J = 8.6 Hz,
2 H), 5.36 (s, 2 H), 4.58 (t, J = 4.5 Hz, 1 H), 4.32 (d, J = 4.2 Hz, 2 H), 3.94 (t, J = 8.6 Hz, 2 H), 3.83-3.80 (m, 2
H), 3.57-3.53 (m, 2 H), 3.37 (s, 3 H), 1.77 (quint, J = 7.4 Hz, 2 H), 1.45 (quint, J = 7.2 Hz, 2 H), 1.38-1.22 (m,
8 H), 0.89 (t, J = 7.0 Hz, 3 H). 13C NMR (125 MHz, CDCl3, , ppm): 165.4, 158.5, 151.1, 148.4, 138.3, 130.6,
129.2, 129.0, 125.5, 123.3, 121.7, 119.8, 114.5, 112.4, 111.3, 93.7, 71.5, 68.0, 67.9, 58.9, 47.3, 31.7,
29.28, 29.20, 29.16, 26.0, 22.6, 14.0. IR (neat): 3425, 2926, 2855, 1730, 1600, 1512, 1493, 1348, 900, 825,
755, 689 cm-1.
14
Figure S1 GPC profiles of products obtained by the polymerization of 1b with 2a in the presence of (A)
LiHMDS at room temperature for 43 h, (B) LiHMDS at 50 oC for 24 h, and (C) KHMDS at 50 oC for 7 h
([1b]0/[2a]0 = 10).
15
PPM
8
7
6
5
4
3
2
1
0
Figure S2 1H NMR spectrum of high-molecular-weight polymer, obtained by the polymerization of 1b
with 10 mol% of 2b in the presence of 1.1 equiv of LiHMDS at room temperature, followed by separation
with preparative HPLC, in CDCl3 at 25 oC.
16
PPM
8
7
6
5
4
3
2
1
0
Figure S3 1H NMR spectrum of high-molecular-weight polymer, obtained by the polymerization of 1b
with 10 mol% of 2b in the presence of 1.1 equiv of KHMDS at 50 oC, followed by purification with
preparative HPLC, in CDCl3 at 25 oC.
17
PPM
8
7
6
5
4
3
2
1
0
Figure S4 1H NMR spectrum of high-molecular-weight polymer obtained by the polymerization of 3a
with 10 mol% of 2b in the presence of 1.1 equiv of LiHMDS at 0 oC, followed by purification with
preparative HPLC, in CDCl3 at 25 oC.
18
PPM
8
7
6
5
4
3
2
1
0
Figure S5 1H NMR spectrum of oligomers, obtained by the polymerization of 3a with 10 mol% of 2b in
the presence of 1.1 equiv of LiHMDS at room temperature, followed by purification with preparative
HPLC, in CDCl3 at 25 oC.
19
Figure S6 TG curves of (A) poly4 and (B) poly5 (PBO) obtained by heating poly4 at 350 oC for 1 h, in
nitrogen at a heating rate of 10 oC/min.
20