2
238 Washio et al.
Macromolecules, Vol. 38, No. 6, 2005
Calcd: [M] m/z ) 1141.1. Found: MALDI-TOF-MS: [M +
ester15b syntheses in amide solvents such as hexameth-
ylphosphoric triamide and N-methyl-2-pyrrolidinone
+
+
+
+
H] ) 1141.3, [M + Na] ) 1163.0, [M + K] ) 1179.3. Anal.
Calcd for C65 14‚0.30H O: C, 68.09%; H, 4.62%; N,
.33%. Found: C, 67.96%; H, 4.71%; N, 7.46%.
H
52
N
6
O
2
(
NMP). Following these syntheses, difficult purification
7
procedures are not necessary because the only byprod-
ucts are gases such as SO2 and HCl. These findings
prompted the development of a facile synthesis of
polyamide dendrimer from an unprotected AB2 building
block. The authors made a brief report of the successful
synthesis of a dumbbell-shaped polyamide G3 den-
drimer, using thionyl chloride as a versatile and com-
mon activating reagent for carboxylic acids, which did
not require tedious purification steps such as column
G3 Dendron (6). Compound 5 (2.062 g, 1.807 mmol) was
placed in a two-necked flask and heated at 150 °C under
reduced pressure for 4 h. Into the flask cooled in a water bath,
7
1
.5 mL of NMP and 1.10 equiv of thionyl chloride (0.145 mL,
.988 mmol) to 5 were added under nitrogen. The reaction
mixture was stirred for 10 min at that temperature and 50
min at room temperature. Then, 0.48 equiv of 3 (0.2894 g,
0.8605 mmol) to 5 was added to the solution, and the reaction
was performed for 5 h at room temperature. The reaction
mixture was poured into water, and the precipitate was
collected and dried. The crude product was redissolved in
NMP, and this was reprecipitated with 1,4-dioxane. The
precipitate was collected and dried in vacuo at 160 °C to give
1
6
chromatography.
This paper presents a detailed polyamide dendrimer
synthesis using thionyl chloride and its application to
the synthesis of a star-shaped dendrimer and a den-
drimer with a carboxylic acid at its core.
-1
a white solid. The yield was 94% (2.089 g). IR (KBr): ν (cm
)
) 3421 (N-H, st), 1658 (CdO(N-H), st), 1589, 1504 (phenyl
1
3 2
ring, st). H NMR (300 MHz, (CD ) SO): δ (ppm) ) 2.02 (s,
Experimental Section
24H), 6.69 (t, 4H), 6.77 (t, 2H), 6.91 (t, 1H), 7.01-7.13 (m, 30H),
7
8
.27 (d, 8H), 7.32 (d, 4H), 7.60 (d,16H), 7.75 (d, 12H), 9.88 (s,
Measurement. Infrared (IR) spectra were recorded on a
+
H), 10.22 (s, 4H), 10.25 (s, 2H). Calcd: [M] m/z ) 2582.6.
1
13
Horiba FT-720 spectrophotometer. H and C NMR spectra
+
Found: MALDI-TOF-MS: [M + Na] ) 2606.3. Anal. Calcd
1
were obtained on a Bruker DPX-300 spectrometer at H, 300
for C149
116 14 2
H N O30‚0.34H O: C, 69.13%; H, 4.54%; N, 7.58%.
1
3
MHz and C, 75 MHz, respectively. Deuterated dimethyl
Found: C, 69.29%; H, 4.70%; N, 7.59%.
6
sulfoxide (DMSO-d ) was used as a solvent with tetrameth-
Dumbbell-Shaped G3 Dendrimer (7). Compound 6 (0.4833
g, 0.1828 mmol) was placed in a two-necked flask and dried
at 150 °C under the reduced pressure for 6 h. Into the flask
cooled with a water bath, 1.7 mL of NMP and 1.50 equiv of
thionyl chloride (20.00 µL, 0.2742 mmol) to 6 were added under
nitrogen. The reaction mixture was stirred for 10 min at that
temperature and 50 min at room temperature. Then, 0.5 equiv
of 4,4′-oxydianiline (0.017 85 g, 0.08917 mmol) to 6 was added
to the solution, and the reaction was performed for 6 h at room
temperature. The reaction mixture was poured into water, and
the precipitate was collected and dried. The crude product was
dissolved in DMF, and this was reprecipitated with THF. The
precipitate was collected and dried in vacuo at 120 °C to give
ylsilane as an internal standard. Matrix-assisted laser desorp-
tion ionization with time-of-flight (MALDI-TOF) mass spectra
were recorded on a Kratos Kompact MALDI instrument
operated in linear detection mode to generate positive ion
spectra using dithranol as a matrix, THF as a solvent, and
sodium trifluoroacetate as an additive agent.
Materials. N-Methyl-2-pyrrolidinone (NMP) was distilled
under reduced pressure over calcium hydride and then stored
under nitrogen. Thionyl chloride was distilled under nitrogen
over triphenyl phosphite and then stored at 0 °C under
nitrogen. The other reagents and solvents were obtained
commercially and used as received.
-1
G1 Dendron (4). To a solution of dendron 3 (4.880 g, 14.51
a white solid. The yield was 74% (0.3517 g). IR (KBr): ν (cm )
mmol) in 25 mL of NMP, 3.0 equiv of acetyl chloride (4.556 g,
) 3421 (N-H, st), 1654 (CdO(N-H), st), 1608, 1504 (phenyl
1
5
8.04 mmol) to 3 was added at 0 °C and stirred for 3 h. The
ring, st). H NMR (300 MHz, (CD ) SO): δ (ppm) ) 2.01 (s,
3
2
reaction mixture was poured into water, and the precipitate
was collected and dried. The precipitate was redissolved in
NMP, and the solution was reprecipitated with water. The
precipitate was collected and dried in vacuo at 120 °C to give
48H), 6.68 (t, 8H), 6.75 (m, 6H), 6.95 (d, 4H), 6.99-7.13 (m,
56H), 7.26 (d, 16H), 7.31 (d, 12H), 7.59 (d, 32H), 7.68 (d, 4H),
7.74 (d, 24H), 9.87 (s, 16H), 10.18 (s, 2H), 10.21 (s, 8H), 10.23
+
(s, 4H). Calcd: [M] m/z ) 5329.4. Found: MALDI-
-
1
+
a white solid. The yield was 98% (5.978 g). IR (KBr): ν (cm
)
TOF-MS: [M + Na] ) 5354.3. Anal. Calcd for C310H240N O ‚
30
59
)
1
2700-3700 (-OH, st), 3294 (N-H, st), 1697 (CdO(OH), st),
13.95H O: C, 66.72%; H, 4.84%; N, 7.53%. Found: C, 66.66%;
H, 4.78%; N, 7.50%.
2
1
658 (CdO(N-H), st), 1597, 1504 (phenyl, st). H NMR (300
MHz, (CD SO): δ (ppm) ) 2.03 (s, 6H), 6.82 (t, 1H), 7.01-
3
)
2
Star-Shaped G1 Dendrimer (9). 1.04 equiv of thionyl
chloride (30.00 µL, 0.4113 mmol) to 4 was added to a solution
of 4 (0.1663 g, 0.3955 mmol) in 1 mL of NMP at 0 °C under
nitrogen and stirred for 15 min at that temperature and for
15 min at room temperature. Then, 0.32 equiv of 8 (0.060 30
g, 0.1255 mmol) to 4 was added to the solution, and the
reaction was carried out for 5 h at room temperature. The
reaction mixture was poured into water, and the precipitate
was collected and dried. The crude product was redissolved
in NMP and diluted with methanol, and the resulting solution
1
3
7
.08 (m, 6H), 7.61 (d, 4H), 9.90 (s, 2H). C NMR (67.5 MHz,
CD SO): δ (ppm) ) 23.9, 111.1, 111.7, 120.2, 120.8, 133.7,
36.1, 150.5, 159.2, 166.1, 168.2. Anal. Calcd for C23
(
3 2
)
1
20 2 6
H N O :
C, 65.71%; H, 4.79%; N, 6.66%. Found: C, 65.59%; H, 4.93%;
N, 6.71%.
G2 Dendron (5). 1.04 equiv of thionyl chloride (0.705 mL,
9.665 mmol) to 4 were added to a solution of 4 (3.907 g, 9.293
mmol) in 20 mL of NMP at 0 °C under nitrogen and stirred
for 15 min at that temperature and for 15 min at room
temperature. Then, 0.48 equiv of 3 (1.488 g, 4.425 mmol) to 4
was added to the solution, and the reaction was carried out
for 4 h at room temperature. The reaction mixture was poured
into water, and the precipitate was collected and dried. The
crude product was redissolved in NMP and diluted with
methanol, and the resulting solution was reprecipitated with
2
was reprecipitated with water (MeOH/H O 4/1 in volume
ratio). The precipitate was collected and dried in vacuo at 120
°C to give a white solid. The yield was 86% (0.1822 g). IR (KBr):
-
1
ν (cm ) ) 3298 (N-H, st), 1664 (CdO(N-H), st), 1608, 1504
1
3 2
(phenyl ring, st). H NMR (300 MHz, (CD ) SO): δ (ppm) )
2.03 (s, 18H), 6.71 (s, 3H), 7.06 (d, 12H), 7.29 (d, 6H), 7.74 (q,
4H), 8.68 (s, 3H), 9.89 (s, 6H), 10.20 (s, 3H), 10.48 (s, 3H).
water (MeOH/H
2
O 1/1 in volume ratio). The precipitate was
+
collected and dried in vacuo at 160 °C to give a white solid.
Calcd: [M] m/z ) 1687.7. Found: MALDI-TOF-MS: [M +
-
1
+
The yield was 92% (4.646 g). IR (KBr): ν (cm ) ) 2700-3700
Na] ) 1710.7. Anal. Calcd for C96
H
N
78 12
O
18‚2.09H
2
O: C,
(
(
2
7
2
1
1
-OH, st), 3417 (N-H, st), 1666 (CdO(N-H), st), 1589, 1504
66.83%; H, 4.80%; N, 9.74%. Found: C, 66.79%; H, 4.76%; N,
9.73%.
1
phenyl ring, st). H NMR (300 MHz, (CD
3
)
2
SO): δ (ppm) )
.03 (s, 12H), 6.70 (t, 2H), 6.89 (t, 1H), 7.01-7.13 (m, 14H),
.28 (d, 4H), 7.60 (d, 8H), 7.76 (d, 4H), 9.87 (s, 4H), 10.22 (s,
Star-Shaped G2 Dendrimer (10). Compound 5 (0.2844
g, 0.2493 mmol) was placed in a two-necked flask and heated
at 150 °C under reduced pressure for 5 h. Into the flask cooled
in a water bath, 1 mL of NMP and 1.10 equiv of thionyl
chloride (20.00 µL, 0.2742 mmol) to 5 were added under
1
3
3 2
H). C NMR (67.5 MHz, (CD ) SO): δ (ppm) ) 23.8, 109.8,
11.1, 111.5, 111.8, 119.7, 119.9, 120.7, 122.4, 133.7, 135.3,
35.8, 137.7, 150.7, 151.2, 158.7, 159.0, 164.0, 166.0, 168.1.