1,3,5-Triaminobenzene (7). NOTE: The product is sensitive to acidic conditions! Prior to this reaction, ethyl acetate was washed with NaOH (2 M) and distilled over Na2CO3. All glassware was successively washed with NaOH (2 M), distilled
water, and iPrOH. To a solution of 8 (3.5 g, 19 mmol) in ethyl acetate (100
mL), Pd/C (0.34 g, 10% (w/w)) and few drops of pyridine were added. The solution was stirred on a hydrogenation machine under a pressure of 3 atm of H2 for 3 h (H2 was being consumed
for approximately 1 h). The solution was separated from Pd/C (which was bound to pyridine) by decantation. Recrystallisation from ethyl acetate provided the pure product (1.8 g, 72%) as a white crystalline solid. The product was stored in the freezer. 1H NMR (300 MHz, DMSO-d
6,
ppm) δ 5.14 (s, 3H, CArH), 4.32 (s, 6H, NH2). 13C NMR (75 MHz, DMSO-d6, ppm) δ 149.3,
90.8. IR (neat, cm–1) ῦ
max 3500–3000, 1593, 1493, 1182, 819, 683. The NMR spectroscopic
data are in agreement with those previously reported.[24]
[Tri(diethylamino)phosphoranylidene]triaz-1-yn-2-ium
hexafluorophosphate (9b). NOTE: This product is hygroscopic! Similar
to the previously described method,[13] N,N,N',N',N'',N''-
hexaethylphosphinetriamine (13.0 mL, 46.8 mmol) was added dropwise to a cooled stirred (0 °C) solution of Br2 (2.42 mL, 46.8 mmol) in THF (60 mL).
The resulting mixture was stirred at 0 °C for an additional 1 h before NaN3
(3.34 g, 56.0 mmol) and a catalytic amount of 18-crown-6 were added. The reaction mixture was then stirred at room temperature for 2 days under an argon atmosphere before a solution of NaPF6 (9.41 g, 56.0 mmol) in THF (30 mL) was added dropwise. Filtration of the crude
reaction mixture provided the pure product (20 g, >99%) as a white crystalline solid. 1H NMR
(400 MHz, CDCl3, ppm) δ 3.16 (dq, JPH = 12.5 Hz, JHH = 7.2 Hz, 12H, CH2), 1,20 (t, J = 7.3
Hz, 18H, CH3). 13C NMR (75 MHz, CDCl3, ppm) δ 40.2 (d, JPC = 4.1 Hz, CH2), 13.2 (d, JPC
= 2.3 Hz, CH3). IR (neat, cm–1) ῦmax 2983, 2923, 2852, 2161 (N3), 1597, 1467, 1386, 1285,
1211, 1154, 1026, 912, 838, 797, 731, 557. HRMS (ESI) m/z calcd for C12H30N6P+:
289.22696; found: 289.22544 (|Δ| = 5.26 ppm). NH2 H2N NH2 PF6– P N N+ N N N N
Chapter 4
116
1,3,5-Triazidobenzene (2). NOTE: This compound has not yet been tested for potential explosive properties!
Method A.[25] Compound 7 (0.94g, 7.7 mmol) was dissolved in THF (60 mL) and cooled to
−78 °C. After the addition of nBuLi (1.6 M in hexane, 5.6 mL, 9.0 mmol), the
solution was stirred for 10 min before 9b (4.0 g, 9.0 mmol in THF (20 mL)) was added dropwise. Two further additions of nBuLi and 3 were carried out (same
quantities as above) and, upon completion of the additions, the resulting mixture was stirred for 1 h at −78 °C before being warmed to RT and treated with NH4Cl (0.25 M, 100 mL). The
aqueous layer was extracted with CH2Cl2 and the organic layer was separated, dried over
Na2SO4, and the solvent was evaporated. The crude mixture was purified by column
chromatography (hexane) on silica gel to provide the product (350 mg, 25%) as light brown crystals.
Method B.[26] A solution of 3 (1.5 g, 4.9 mmol) in THF (12 ml) was added dropwise to a
cooled solution (–78 °C) of nBuLi (27 mL, 44 mmol, 1.6M in hexanes) in THF (50 mL) and
the mixture was stirred for 15 min at the same temperature. After the dropwise addition of a solution of 10 (8.6 g, 44 mmol) in THF (9 mL), the mixture was warmed to room temperature and stirred overnight. The reaction was quenched with NH4Cl (50 mL, 1 M). The aqueous
layer was extracted three times with Et2O and the combined organic layers were dried over
Na2SO4. After filtration, the solvent was evaporated and the crude mixture was purified by
column chromatography, with pentane as the eluent, to provide the product (0.25 g, 26%). 1H
NMR (300 MHz, CDCl3, ppm) δ 6.45 (s, 3H, CArH). 13C NMR (75 MHz, CDCl3, ppm) δ
143.2, 106.1. IR (neat, cm–1) ῦ
max 2145 (N3), 2119 (N3), 2097 (N3), 1590, 1463, 1267, 943,
832, 690, 667. The molecular ion signal could not be detected by any of the available MS techniques.
[(5-Ethynyl-1,3-phenylene)bis(ethyne-2,1-
diyl)]bis[dimethyl(octadecyl)silane] (11). Compound 1 (0.50 g, 3.3 mmol) in THF (30 mL) was cooled to −78°C, and treated with nBuLi
(1.6 M in hexanes, 2.08 mL, 3.33 mmol). After stirring for 20 min, chlorodimethyl(octadecyl)silane (1.25 g, 3.5 mmol) in THF (20 mL) was added. The addition of nBuLi and chlorodimethyl(octadecyl)silane was
repeated after a further 30 min. The reaction mixture was allowed to warm to room temperature, and then stirred overnight, before it was quenched with water and extracted with CH2Cl2. The organic layer was separated, dried over Na2SO4, and the solvent was removed to
give a mixture of three reaction products as a brown oil. The products were separated by column chromatography (hexane) on silica gel to give 11 as a colourless oil (0.90 g, 36%), 12 as white crystals (0.20 g, 14%), and 13 in the form of light brown crystals (1.3 g, 36%). 1H
NMR (300 MHz, CDCl3, ppm) δ 7.52 (t, J = 1.5 Hz, 1H, CArH), 7.49 (d, J = 1.6 Hz, 2H, CArH), 3.07 (s, 1H, CCH), 1.48−1.18 (m, 64H, CH2), 0.92–0.82 (m, 6H, CH2CH3), 0.71– 0.62 (m, 4H, SiCH2), 0.20 (s, 12H, SiCH3). 13C NMR (75 MHz, CDCl3, ppm) δ (6C N3 N3 N3 SiC18H37 SiC18H37
Click graphene 117 overlapped) 135.5, 135.2, 124.0, 122.8, 103.2, 95.6, 81.8, 78.4, 33.2, 32.0, 29.74, 29.72, 29.68, 29.6, 29.38, 29.35, 23.8, 22.7, 16.0, 14.1, −1.8. IR (neat, cm–1) ῦ max 3308, 2954, 2921, 2852, 2160, 1578, 1464, 1413, 1249, 1162, 984, 949, 884, 840, 826, 779, 711, 682, 651, 621. Anal calcd for C52H90Si2 80.96 (C), 11.76 (H); found: 80.95 (C), 11.74 (H). The molecular
ion signal for the products of this reaction 11, 12 and 13 could not be detected by any of the available MS techniques.
[(3,5-Diethynylphenyl)ethynyl]dimethyl(octadecyl)silane (12). Compound 12 was isolated as a side product of the synthesis of 11. 1H NMR (300 MHz,
CDCl3, ppm) δ 7.54 (d, J = 1.5 Hz, 2H, CArH), 7.52 (t, J = 1.5 Hz, 1H, CArH), 3.08 (s, 2H, CCH), 1.48−1.15 (m, 32H, CH2), 0.92–0.82 (m, 3H, CH2CH3), 0.72–0.62 (m, 2H, SiCH2), 0.20 (s, 6H, SiCH3). 13C NMR (75 MHz, CDCl3, ppm) δ (6C overlapped) 135.5, 135.2, 124.0, 122.8, 103.2, 95.7, 81.8, 78.4, 33.2, 31.9, 29.74, 29.72, 29.67, 29.6, 29.4, 29.3, 23.8, 22.7, 16.0, 14.1, −1.8. IR (neat, cm–1) ῦmax 3307, 2953, 2920, 2850, 2162, 2122, 1577, 1464, 1412, 1297, 1249, 1158, 968, 884, 842, 826, 779. 1,3,5-Tris{[dimethyl(octadecyl)silyl]ethynyl}benzene (13). Compound 13 was isolated as a side product of the synthesis of 11. 1H NMR
(300 MHz, CDCl3, ppm) δ 7.47 (s, 3H, CArH), 1.50−1.15 (m, 96H, CH2), 0.95–0.82 (m, 9H, CH2CH3), 0.73–0.60 (m, 4H, SiCH2), 0.20 (s, 12H, SiCH3). 13C NMR (75 MHz, CDCl3, ppm) δ (6C overlapped) 135.5, 135.2, 124.0, 122.8, 103.2, 95.6, 81.8, 78.4, 33.2, 32.0, 29.74, 29.72, 29.68, 29.6, 29.38, 29.35, 23.8, 22.7, 16.0, 14.1, −1.8. IR (neat, cm–1) ῦ max 3308, 2954, 2921, 2852, 2160, 1578, 1464, 1413, 1249, 1162, 984, 949, 884, 840, 826, 779, 711, 682, 651, 621.
4-(3,5-Dibromophenyl)-2-methylbut-3-yn-2-ol (18). See General Procedure 2.2 (p. 62): 3 (2.0 g, 6.35 mmol), CuI (8 mg, 37 µmol), [Pd(PPh3)4] (7.3 mg, 6
µmol), THF/Et3N (20 mL, 1/1), 2-methylbut-3-yn-2-ol (0.53 g, 6.35 mmol),
60 °C, 15 h. Column chromatography on silica gel, with pentane/ethyl acetate (1/1) as the eluent, afforded the pure product (1.4 g, 70%) as a yellow solid, and the product of the bis-coupling 26 (0.24 g, 12%) as a white solid. 1H NMR (300
MHz, CDCl3, ppm) δ 7.61 (t, J = 1.8 Hz, 1H, CArH), 7.49 (d, J = 1.8 Hz, 2H, CArH), 2.19 (s,
1H, OH), 1.60 (s, 6H, CH3). 13C NMR (75 MHz, CDCl3, ppm) δ 134.0, 133.1, 126.1, 122.5,
96.4, 79.3, 65.5, 31.3. IR (neat, cm–1) ῦ
max 3343, 2980, 2358, 2328, 1580, 1541, 1398, 1165,
746. HRMS (EI) m/z calcd for C11H10Br2O: 315.9101; found: 315.9102 (|Δ| = 0.3 ppm).
4,4'-(5-Bromo-1,3-phenylene)bis(2-methylbut-3-yn-2-ol)(26). Compound 26 was isolated as a side product of the synthesis of 18 and a dedicated synthetic procedure for this compound was reported elsewhere.[27] 1H
NMR (300 MHz, CDCl3, ppm) δ 7.47 (d, J = 1.4 Hz, 2H, CArH), 7.38 SiC18H37 SiC18H37 Si C18H37 Br Br OH Br OH OH SiC18H37
Chapter 4
118
(t, J = 1.4 Hz, 1H, CArH), 2.21 (s, 2H, OH), 1.59 (s, 12H, CH3). 13C NMR (75 MHz, CDCl3,
ppm) δ 134.0, 133.3, 124.7, 121.7, 95.6, 80.0, 65.5, 31.3. IR (neat, cm–1) ῦ
max 3329, 2978,
2932, 2866, 2247, 1584, 1552, 1424, 1363, 1241, 1164, 1147. The NMR spectroscopic data were in agreement with those previously reported.
4-{3-Bromo-5-[(triisopropylsilyl)ethynyl]phenyl}-2-methylbut-3-yn-2-ol (19). See General Procedure 2.2 (p. 62): 18 (1.0 g, 3.23 mmol), CuI (3.9 mg, 20 µmol), [Pd(PPh3)4] (3.9 mg, 3 µmol), THF/Et3N (10 mL, 1/1),
(triisopropylsilyl)acetylene (0.59 g, 3.23 mmol), room temperature, 3 days. Column chromatography on silica gel, with pentane/ethyl acetate (5/1) as the eluent, afforded the pure product (0.8 g, 60%) as a yellow oil. 1H NMR
(300 MHz, CDCl3, ppm) δ 7.53 (t, J1 = 1.8 Hz, J2 = 1.5 Hz, 1H, CArH),
7.48 (t, J1 = 1.8 Hz, J2 = 1.5 Hz, 1H, CArH), 7.44 (t, J1 = 1.5 Hz, J2 = 1.5 Hz, 1H, CArH), 2.04
(s, 1H, OH), 1.60 (s, 6H, CH3), 1.12 (m, 21H). 13C NMR (75 MHz, CDCl3, ppm) δ 134.3,
134.0, 133.6, 125.4, 124.6, 121.6, 104.4, 95.7, 93.1, 80.0, 65.5, 31.3, 18.6, 11.2. IR (neat, cm–1) ῦ
max 3322, 2941, 2863, 2154, 1584, 1554, 1217, 1165, 880, 672. Anal calcd for
C22H31BrOSi: C 62.99, H 7.45; found: C 62.85, H 7.52.
2-Methyl-4-{3-[(triisopropylsilyl)ethynyl]-5-
[(trimethylsilyl)ethynyl]phenyl}but-3-yn-2-ol (20). See
General Procedure 2.2 (p. 62): 19 (0.51 g, 1.22 mmol), CuI (4.6 mg, 24 µmol), [Pd(PPh3)4] (28.4 mg, 24 µmol), THF/Et3N (10 mL, 1/1),
(trimethylsilyl)acetylene (0.14 g, 1.46 mmol), 60 °C, 15 h. Column chromatography on silica gel, with pentane/ethyl acetate (4/1) as the eluent, afforded the pure product (0.5 g, 97%) as a yellow oil. 1H NMR
(300 MHz, CDCl3, ppm) δ 7.48 (t, J = 1.5 Hz, 1H, CArH), 7.45–7.43 (m, 2H, CArH), 2.02 (s,
1H, OH), 1.60 (s, 6H, CH3). 1.12 (m, 21H), 0.24 (s, 9H, SiCH3). 13C NMR (75 MHz,
CDCl3, ppm) δ 134.8, 134.7, 134.6, 124.0, 123.6, 123.2, 105.1, 103.2, 95.6, 94.8, 92.1, 80.6,
65.5, 31.4, 18.6, 11.2, –0.2. IR (neat, cm–1) ῦ
max 3339, 2937, 2859, 2154, 1580, 1459, 1411,
1247, 1165, 983, 880, 845, 759, 681. Anal calcd for C27H40OSi2: C 74.25, H 9.23; found: C
74.49, H 9.35.
4-{3-Ethynyl-5-[(triisopropylsilyl)ethynyl]phenyl}-2-methylbut-3-yn-2- ol (21). See General Procedure 2.3 (p. 62): 20 (0.43 g, 0.98 mmol), K2CO3 (1.35 g, 10 mmol), THF/MeOH (50 mL, 4/1), room temperature,
1 h. Purification on a short column of silica gel, with heptane/ethyl acetate (4/1) as the eluent, provided the pure product (0.34 g, 96%) as a colourless
oil. 1H NMR (300 MHz, CDCl 3, ppm) δ 7.51 (t, J = 1.5 Hz, 1H, CArH), 7.48 (t, J = 1.5 Hz, 1H, CArH), 7.46 (t, J = 1.5 Hz, 1H, CArH), 3.07 (s, 1H, CCH), 2.04 (s, 1H, OH), 1.60 (s, 6H, CH3), 1.12 (m, 21H). 13C NMR (75 MHz, CDCl3, ppm) δ 135.1, 135.0, 134.6, 124.1, 123.4, 122.6, 105.0, 95.0, 92.4, 81.9, 80.5, 78.3, 65.5, Br Si OH Si OH Si Si OH
Click graphene
119 31.4, 18.6, 11.2. IR (neat, cm–1) ῦ
max 3304, 2940, 2863, 2155, 1577, 1463, 1411, 1364, 1223,
1167, 959, 881, 679. Anal calcd for C24H32OSi: C 79.06, H 8.85; found: C 79.42, H 9.97.
4-{3,5-Bis[(trimethylsilyl)ethynyl]phenyl}-2-methylbut-3-yn-2-ol (24).
See General Procedure 2.2 (p. 62): 18 (0.5 g, 1.57 mmol), CuI (30 mg, 0.16 mmol), [Pd(PPh3)4] (91 mg, 79 µmol), THF/Et3N (20 mL, 1/1),
(trimethylsilyl)acetylene (0.46 g, 4.72 mmol), 60 °C, 15 h. Column chromatography on silica gel, with heptane/ethyl acetate (2/1) as the eluent, afforded the pure product (0.5 g, 90%) as a yellow oil. 1H NMR
(300 MHz, CDCl3, ppm) δ 7.49 (t, J = 1.5 Hz, 1H, CArH), 7.44 (d, J = 1.6 Hz, 2H, CArH),
1.99 (s, 1H, OH), 1.59 (s, 6H, CH3), 0.23 (s, 18H, SiCH3). 13C NMR (75 MHz, CDCl3,
ppm) δ 134.8, 134.6, 123.7, 123.2, 103.1, 95.6, 94.8, 80.5, 65.5, 31.4, –0.2. IR (neat, cm–1)
ῦmax 3343, 2963, 2155, 1580, 1416, 1251, 1161, 983, 841, 759, 646. The spectroscopic data
were in agreement with those previously reported.[28]
4-(3,5-Diethynylphenyl)-2-methylbut-3-yn-2-ol (25). See General Procedure 2.3 (p. 62): 24 (0.5 g, 1.42 mmol), K2CO3 (2.0 g, 14 mmol), THF/MeOH (50
mL, 4/1), room temperature, 2 h. Purification on a short column of silica gel, with heptane/ethyl acetate (2/1) as the eluent, provided the pure product (0.21 g, 68%) as a colourless oil. 1H NMR (300 MHz, CDCl 3, ppm) δ 7.52 (t, J = 1.4 Hz, 1H, CArH), 7.50 (d, J = 1.4 Hz, 2H, CArH), 3.09 (s, 2H, CCH), 2.05 (s, 1H, OH), 1.60 (s, 6H, CH3). 13C NMR (75 MHz, CDCl3, ppm) δ 135.2, 135.1, 123.5, 122.8, 95.21, 81.7, 80.3, 78.5, 65.5, 31.3. IR (neat, cm–1) ῦ max 3287, 2980, 2358, 1580, 1415, 1221, 1165, 945, 884, 611. 4,4'-[5-(Dodec-1-yn-1-yl)-1,3-phenylene]bis(2-methylbut-3-yn-2-ol) (27). See General Procedure 2.2 (p. 62): 26 (1.36 g, 4.2 mmol), CuI (49 mg, 0.21 mmol), [Pd(PPh3)4] (116 mg, 0.11 mmol), THF/Et3N (15
mL, 1/2), 1-dodecyne (1.1 g, 6.3 mmol), 50 °C, 15 h. Column chromatography on silica gel, with heptane/ethyl acetate (4/1) as the eluent, afforded the pure product (1.1 g, 63%) as a yellow oil. 1H NMR
(300 MHz, CDCl3, ppm) δ 7.38–7.32 (m, 3H, CArH), 2.37 (t, J = 7.0 Hz, 2H, CCH2), 2.04 (s, 2H, OH), 1.59 (s, 12H, CCH2), 1.58–1.50 (m, 2H, CH2), 1.48–1.36 (m, 2H, CH2), 1.36–1.20 (m, 12H, CH2), 0.88 (t, J = 6.6 Hz, 3H, CH3). 13C NMR (75 MHz, CDCl3, ppm) δ 134.2, 133.5, 124.6, 123.1, 94.6, 91.9, 80.73, 65.5, 31.9, 31.4, 29.6, 29.5, 29.3, 29.1, 28.9, 28.6, 22.7, 19.3, 14.1. IR (neat, cm–1) ῦ max 3347, 2976, 2924, 2859, 2349, 2232, 1696, 1584, 1455, 1359, 1238, 1169, 945, 880, 681, 556.
1-(Dodec-1-yn-1-yl)-3,5-diethynylbenzene (28). See General Procedure 2.3 (p. 62): 27 (0.39 g, 0.96 mmol), NaOH (0.77 g, 19 mmol), toluene (100 mL), reflux, 15 h. Column chromatography over silica gel, with pentane as the eluent, afforded the pure product (0.18 mg, 71%) as a white solid. 1H NMR (300
MHz, CDCl3, ppm) δ 7.50 (t, J = 1.4 Hz, 1H, CArH), 7.49 (d, J = 1.4 Hz, 2H, C10H21 OH OH C10H21 OH TMS TMS OH
Chapter 4 120 CArH), 3.09 (s, 2H, CCH), 2.40 (t, J = 7.0 Hz, 2H, CCH2), 1.68–1.52 (m, 2H, CH2), 1.52– 1.39 (m, 2H, CH2), 1.39–1.23 (m, 12H, CH2), 0.97–0.86 (m, 3H, CH3). 13C NMR (75 MHz, CDCl3, ppm) δ 135.2, 134.3, 124.9, 122.6, 92.3, 82.0, 78.8, 78.1, 31.9, 29.6, 29.5, 29.3, 29.1, 28.9, 28.5, 22.7, 19.3, 14.1. IR (neat, cm–1) ῦ max 3304, 2924, 2855, 2237, 2111, 1778, 1576, 1467, 1411, 1230, 880, 655, 620.
2-[2-(2-Dethoxyethoxy)ethoxy]ethyl 3,5-dinitrobenzoate (36). According to the previously described method,[29] in a three-necked flask, 34 (21.8 g,
103 mmol) and 35 (14.6 g, 89.2 mmol) were dissolved in dry THF (60 mL). After cooling the mixture to 0 °C under an argon atmosphere, DPTS (6.57 g, 22.3 mmol) dissolved in CH2Cl2 (100 mL) was added. To this mixture, DIC
(14.6 g, 116 mmol) was added dropwise over 5 min, whereupon the mixture became viscous. After 10 min, the mixture was allowed to reach room temperature and was stirred overnight. The reaction was quenched with water (70 mL) and stirred for 50 min. After removal of the solvents, the residue was dried under vacuum for 1 h. Then toluene (400 mL) was added and the mixture was heated to 80 °C under stirring to achieve a homogenous suspension. After cooling, the white solid was filtered off. Column chromatography on silica gel, with pentane/ethyl acetate (7/3 →8/5→1/1→2/3→0/1) as the eluent, afforded the pure product (31.3 g, 98%) as a pale white oil. 1H NMR (300 MHz, CDCl
3, ppm) δ 9.22 (t, J = 2.1 Hz, 1H,
CArH), 9.17 (d, J = 2.1 Hz, 2H, CArH), 4.63–4.57 (m, 2H, OCH2), 3.92–3.86 (m, 2H, OCH2),
3.75–3.61 (m, 6H, OCH2), 3.56–3.50 (m, 2H, OCH2), 3.35 (s, 3H, OCH3). 13C NMR (75
MHz, CDCl3, ppm) δ 162.5, 148.6, 133.8, 129.5, 122.4, 71.9, 70.7, 70.62, 70.59, 68.7, 65.8,
58.9. IR (neat, cm–1) ῦ
max 3099, 2880, 2821, 1727, 1631, 1545, 1459, 1346, 1273, 1169, 1096,
923, 854, 716.
2-[2-(2-Methoxyethoxy)ethoxy]ethyl 3,5-diaminobenzoate (37). According to the previously described method,[29] 36 (31.0 g, 86.6 mmol) was
combined with Pd/C (3.1 g, 10% (w/w)) in ethyl acetate (150 mL) and the mixture was stirred under H2 for 4 h. After the mixture was stirred at room
temperature overnight under H2, it was filtered through Celite and the solvent was evaporated.
This provided the pure product (25.8 g, >99%) as a yellow–brown oil. 1H NMR (300 MHz,
DMSO-d6, ppm) δ 6.44 (d, J = 2.1 Hz, 2H, CArH), 6.03 (t, J = 2.1 Hz, 1H, CArH), 4.31–4.25
(m, 2H, OCH2), 3.71–3.65 (m, 2H, OCH2), 3.59–3.54 (m, 2H, OCH2), 3.54–3.49 (m, 4H,
OCH2), 3.43–3.39 (m, 2H, OCH2), 3.22 (s, 3H, OCH3). 13C NMR (75 MHz, DMSO-d6,
ppm) δ 166.8, 149.3, 130.6, 103.8, 103.7, 71.3, 69.9, 69.8, 69.6, 68.5, 63.4, 58.0. IR (neat, cm–1) ῦ
max 3434, 3352, 2881, 1705, 1601, 1459, 1372, 1234, 1096, 845, 767.
3,5-Diaminobenzoic acid (38). Compound 34 (10.0 g, 47.2 mmol) was combined with Pd/C (1 g, 10% (w/w)) in ethyl acetate (200 mL) and the mixture was stirred vigorously under H2 for 5 h. After the mixture was stirred at
room temperature overnight under H2, MeOH was added to the solution. The
precipitate was filtered through Celite, and washed with MeOH. This provided the pure
O2N NO2 O O O 3 H2N NH2 O O O 3 H2N NH2 O OH
Click graphene
121 product (7.0 g, 97%) as a brown solid. 1H NMR (300 MHz, DMSO-d
6, ppm) δ 6.42 (d, J =
2.0 Hz, 2H, CArH), 6.01 (t, J = 2.0 Hz, 1H, CArH). 13C NMR (75 MHz, DMSO-d6, ppm) δ
168.4, 149.2, 131.7, 104.1, 103.6. The NMR spectroscopic data were in agreement with those previously reported.[30]
3,5-Diazidobenzoic acid (39). According to a previously described method,[31] to
an ice-cooled, stirred suspension of 38 (5.95 g, 39.1 mmol) in 25% sulfuric acid (160 mL), an aqueous solution of sodium nitrite (2.5 M, 40.0 mL, 98.3 mmol) was added dropwise. The colour of the originally red suspension changed to orange. After 2 h, urea (7.0 g, 0.12 mol), followed by NaN3 (12.7 g, 0.20 mol) in
water (35 mL), were slowly added, while keeping the temperature below –5 °C. After stirring the suspension overnight at room temperature in the dark, excess water was added and the solution was neutralised with an aqueous solution of NaOH (2M). The mixture was extracted with ethyl acetate, and the combined organic layers were filtered and then heated at reflux in the presence of charcoal for 30 min. After filtering off the charcoal, the solution was washed with a saturated aqueous solution of NaHCO3, dried over Na2SO4 and filtered. Evaporation of
ethyl acetate provided the pure product (2.8 g, 35%) as an orange solid. 1H NMR (400 MHz,
DMSO-d6, ppm) δ 7.37 (d, J = 2.1 Hz, 2H, CArH), 7.02 (t, J = 2.0 Hz, 1H, CArH). 13C NMR
(75 MHz DMSO-d6, ppm) δ 170.0, 149.6, 132.8, 105.6, 104.6. IR (neat, cm–1) ῦmax 3442,
2920, 2850, 2124, 1705, 1593, 1467, 1264, 854, 767, 612. The spectroscopic data were in agreement with those previously reported.[2c]
2-[2-(2-Methoxyethoxy)ethoxy]ethyl 3,5-diazidobenzoate (40). According to a previously described method,[29] in a three-necked flask, 39 (2.8 g, 13.7
mmol) and 35 (2.0 g, 11.9 mmol) were dissolved in dry THF (100 mL). After cooling the mixture to 0 °C under an argon atmosphere, DPTS (0.88 g, 2.98 mmol) dissolved in CH2Cl2 (25 mL) was added. To this mixture, DIC (1.0 g,
15.5 mmol) was added dropwise over 5 min, whereupon the mixture became viscous. After 10 min, the mixture was allowed to reach room temperature and was stirred overnight. The reaction was quenched with water (50 mL) and stirred for 30 min. After removal of the solvents, the residue was dried under vacuum for 30 min. Then toluene (500 mL) was added and the mixture was sonicated under stirred to achieve a homogenous suspension. After cooling, the white solid was filtered off. Column chromatography on silica gel, with CH2Cl2/acetone (100/0
to 98/2) as the eluent, afforded the pure product (3.4 g, 81%) as a yellow oil. 1H NMR (300
MHz, CDCl3, ppm) δ 7.49 (d, J = 2.1 Hz, 2H, CArH), 6.80 (t, J = 2.1 Hz, 1H, CArH), 4.51–
4.46 (m, 2H, OCH2), 3.85–3.81 (m, 2H, OCH2), 3.73–3.70 (m, 4H, OCH2), 3.69–3.63 (m,
2H, OCH2), 3.56–3.52 (m, 2H, OCH2), 3.37 (s, 3H, OCH3). 13C NMR (75 MHz, CDCl3,
ppm) δ 164.8, 142.2, 133.3, 116.4, 113.8, 71.9, 70.69, 70.65, 70.60, 69.0, 64.7, 59.0. IR (neat, cm–1) ῦ max 2876, 2111, 1727, 1597, 1455, 1324, 1260, 1104, 1031, 867, 758. N3 N3 O OH N3 N3 O O O 3
Chapter 4
122
3,5-Bis-[(trimethylsilyl)ethynyl]benzoic acid (42). See General Procedure 2.2 (p. 62): 41 (1.6 g, 5.8 mmol), CuI (219 mg, 1.15 mmol), [Pd(PPh3)4]
(609 mg, 0.58 mmol), THF/Et3N (15 mL, 1/2), TMSA (2.24 g, 23
mmol), 70 °C, 15 h. Column chromatography on silica gel, with heptane/ethyl acetate/acetic acid (1/1/0.002) as the eluent, afforded the pure product (1.1 g, 61%) as a yellow oil. 1H NMR (400 MHz, CDCl
3, ppm) δ 8.12 (d, J =
1.6 Hz, 2H, CArH), 7.76 (t, J = 1.6 Hz, 1H, CArH), 0.26 (s, 18H, SiCH3). The NMR
spectroscopic data were in agreement with those previously reported.[32]
2-[2-(2-Methoxyethoxy)ethoxy]ethyl 3,5-bis[(trimethylsilyl)ethynyl]
benzoate (43). According to a previously described method,[29] in a
three-necked flask, 42 (1.1 g, 3.5 mmol) and 34 (0.5 g, 3.0 mmol) were dissolved in dry THF (20 mL). After cooling the mixture to 0 °C under an argon atmosphere, DPTS (0.22 g, 0.76 mmol) dissolved in CH2Cl2 (20 mL) was added. To this mixture, DIC (0.5 g, 4.0 mmol)
was added dropwise over 5 min, whereupon the mixture became viscous. After 10 min, the mixture was allowed to reach room temperature and was stirred overnight. The reaction was quenched with water (50 mL) and stirred for 30 min. After removal of the solvents, the residue was dried under vacuum for 1 h. Then toluene (200 mL) was added and the mixture was stirred to achieve a homogenous suspension. After cooling, the white solid was filtered off. Column chromatography on silica gel, with pentane/ethyl acetate (7/1→5/1→3/1) as the eluent, afforded the pure product (1.35 g, 85%) as a yellow thick oil. 1H NMR (300 MHz, CDCl
3,
ppm) δ 8.05 (d, J = 1.6 Hz, 2H, CArH), 7.73 (t, J = 1.6 Hz, 1H, CArH), 4.51–4.44 (m, 2H,
OCH2), 3.86–3.80 (m, 2H, OCH2), 3.74–3.62 (m, 6H, OCH2), 3.56–3.51 (m, 2H, OCH2),
3.37 (s, 3H, OCH3), 0.25 (s, 18H, SiCH3). 13C NMR (75 MHz, CDCl3, ppm) δ 165.1, 139.1,
132.7, 130.5, 123.8, 102.9, 96.2, 71.9, 70.64, 70.61, 70.59, 69.1, 64.4, 59.0, –0.2. IR (neat, cm–1) ῦ
max 2954, 2876, 2159, 1727, 1588, 1433, 1312, 1251, 1221, 1109, 983, 845, 763.
2-[2-(2-Methoxyethoxy)ethoxy]ethyl 3,5-diethynylbenzoate (44). See General Procedure 2.3 (p. 62): 43 (555 mg, 1.21 mmol), TBAF (234 µL, 1 M solution in THF), THF (30 mL), room temperature, 1 h. Column chromatography on silica gel, with pentane/ethyl acetate (5/1) as the eluent, afforded the pure product (286 mg, 75%) as a brown oil. 1H NMR (300
MHz, CDCl3, ppm) δ 8.12 (d, J = 1.6 Hz, 2H, CArH), 7.76 (t, J = 1.6 Hz, 1H, CArH), 4.53–
4.42 (m, 2H, OCH2), 3.90–3.77 (m, 2H, OCH2), 3.76–3.61 (m, 6H, OCH2), 3.58–3.48 (m,
2H, OCH2), 3.36 (s, 3H, OCH3), 3.14 (s, 2H, CCH). 13C NMR (75 MHz, CDCl3, ppm) δ
164.9, 139.4, 133.3, 130.8, 123.0, 81.6, 78.9, 71.9, 70.7, 70.62, 70.61, 69.0, 64.6, 59.0. IR (neat, cm–1) ῦ
max 3256, 2876, 2107, 1718, 1588, 1437, 1307, 1212, 1104, 1027, 906, 757, 677.
MALDI-ToF MS (dithranol) m/z calcd for C18H20O5 + Na+: 339.12; found: 338.99. O OH TMS TMS O O O 3 Si Si O O O 3
Click graphene
123 4.5.2 Synthesis of dendrimers by means of the single-protecting-group
approach
1,3,5-Tris[4-(3,5-bis{[dimethyl(octadecyl)silyl]ethynyl}phenyl)-1H- 1,2,3-triazol-1-yl]-benzene (14). See General Procedure 2.2 (p. 62): 2 (27 mg, 0.14 mmol), 11 (0.31 mg, 0.41 mmol), CuI (26 mg, 0.14 mmol), and PMDTA (24 mg, 0.14 mmol), THF (20 mL), room temperature, 24 h. SEC using CH2Cl2
provided 14 (0.2 g, 60%) as a brown oil. 1H NMR
(300 MHz, CDCl3, ppm) δ 8.51 (s, 3H, CArH), 8.46 (s, 3H, CArH), 8.01 (d, J = 1.5 Hz, 6H, CArH), 7.60 (t, J = 1.5 Hz, 3H, CArH), 1.47–1.24 (m, 192H, CH2), 0.87 (t, J = 6.6 Hz, 18H, CH2CH3), 0.71 (t, J = 7.6 Hz, 12H, SiCH2), 0.24 (s, 36H, SiCH3). 13C NMR (70 MHz, CDCl3, ppm) δ (8C overlapped) 147.9, 139.1, 135.4, 129.7, 129.1, 124.4, 117.7, 110.4, 103.7, 95.4, 33.3, 31.9, 29.7, 29.70, 29.65, 29.4, 23.8, 22.7, 16.1, 14.1, –1.8. IR (neat, cm–1) ῦ max 2958, 2911, 2853,
2154, 1617, 1503, 1464, 1258, 1091, 1031, 854. MALDI-ToF MS (HABA, AgNO3) m/z
calcd for C162H273N9Si6 + Na+: 2636.01; found: 2535.62.
1,3,5-Tris[4-(3,5-diethynylphenyl)-1H-1,2,3-triazol-1-yl]benzene (5). See General Procedure 2.3 (p. 62): 14 (93 mg, 37 µmol), K2CO3
(103.5 mg, 0.75 mmol), THF/MeOH (4/1, 50 mL), room temperature, 12 h. Purification on a short column of silica gel, with CHCl3, followed by THF/MeOH (20/1) as the eluent,
provided the pure product (24 mg, 99%) as a white solid. 1H
NMR (300 MHz, THF-d8, ppm) δ 9.28 (s, 3H, CArH), 8.75 (s, 3H, CArH), 8.16 (d, J = 1.5 Hz, 6H, CArH), 7.58 (t, J = 1.5 Hz, 3H, CArH), 3.74 (s, 6H, CCH). 13C NMR (75 MHz, THF-d8, ppm) δ 147.5, 140.1, 135.3, 132.2, 129.7, 124.5, 120.4, 110.5, 82.7, 79.7. IR (neat, cm–1) ῦ max 3330–3150 (br), 2921, 2850, 2161, 2107, 1726, 1620, 1606, 1515, 1496, 1232, 1035, 880, 832. MALDI-ToF MS (dithranol, AgNO3) m/z calcd for C42H20AgN9 – N2 + (H+ + Na+): 753.98; found: 752.83.
The molecular formula C42H20AgN9 corresponded to the silver(I) acetylide of 5 (C42H21AgN9 –
H+ + Ag+). N N N N N N N N N Si Si C18H37 C18H37 Si C18H37 Si C18H37 Si C18H37 Si C18H37 N N N N N N N N N
Chapter 4
124
4-(3,5-Bis{[dimethyl(octadecyl)silyl]ethynyl}phenyl)-1-(3,5-
diazidophenyl)-1H-1,2,3-triazole (15). A solution of 11 (0.36 g, 0.47 mmol), CuI (18 mg, 94 µmol), and PMDTA (24 mg, 0.14 mmol) in THF (60 mL) was slowly added dropwise to a stirred solution of 2 (0.47 g, 2.3 mmol) in THF (10 mL) at room temperature for 2 h. After 20 h, CH2Cl2 was added to the reaction mixture and the organic layer
was washed 3 times with NH4Cl (50 mL, 1 M). The organic layer was
separated, dried over Na2SO4, and the solvent was evaporated. SEC,
with CH2Cl2 as the eluent, provided the pure product (0.26 g, 60%) as a white solid. 1H NMR
(300 MHz, CDCl3, ppm) δ 8.19 (s, 1H, CArH), 7.94 (d, J = 1.5 Hz, 2H, CArH), 7.57 (t, J = 1.5 Hz, 1H, CArH), 7.24 (d, J = 2.1 Hz, 2H, CArH), 6.73 (t, J = 2.1 Hz, 1H, CArH), 1.46–1.25 (m, 64H, CH2), 0.88 (t, J = 6.8 Hz, 6H, CH2CH3), 0.70 (t, J = 8.0 Hz, 4H, SiCH2), 0.23 (s, 12H, SiCH3). 13C NMR (75 MHz, CDCl3, ppm) δ (7C overlapped) 147.3, 143.6, 139.0, 135.2, 130.0, 129.0, 124.3, 117.7, 109.4, 107.2, 103.8, 95.3, 33.3, 31.9, 29.73, 29.70, 29.65, 29.6, 29.4, 23.8, 22.7, 16.1, 14.1, –1.8. IR (neat, cm–1) ῦ max 2956, 2922, 2851, 2154, 2113, 1600,
1466, 1249, 840, 613. MALDI-ToF MS (dithranol) m/z calcd for C58H93N9Si2 + H+: 972.72;
found: 972.50. 1,3,5-Tris{4-[3,5-bis(4-{3-azido-5-[4-(3,5-bis{[dimethyl(octadecyl)silyl] ethynyl}phenyl)- 1H-1,2,3-triazol-1- yl]phenyl}-1H- 1,2,3-triazol-1- yl)phenyl]-1H- 1,2,3-triazol}-1- yl)benzene (16). Under a nitrogen atmosphere, to a stirred solution of 15 (85 mg, 87 mmol) in THF (10 mL), a solution of 5 (5.3 mg, 7.8 mmol), Cul (17 mg 87 mmol) and PMDTA (15 mg, 87 mmol) in THF (60 mL) was added
dropwise over 4 h. The resulting mixture was then stirred for an additional 15 h at room temperature under an argon atmosphere before it was diluted with CH2Cl2. The organic solution was then washed with NH4OH (50 mL, 10%)
Si C18H37 Si C18H37 N N N N3 N3 N N N N N N N N N N N N N N N NN N NN N N N N N N N Si Si C18H37 C18H37 N N N N N N Si Si Si Si C18H37 C18H37 C18H37 C18H37 N3 N N N N N3 N N Si Si C18H37 C18H37 N N3 N3 N3 N3 N N N N N Si Si Si Si C18H37 C18H37 C18H37 C18H37
Click graphene
125 and an aqueous solution of NH4Cl (1 M), and dried over Na2SO4. After filtration, the solvents
were evaporated and the residue was purified by SEC, with CH2Cl2 as the eluent, to afford a
yellowish solid (20 mg, 21%) and the recovered starting compound 15 (34 mg, 40%). Repeatedly, the desired product 16 could not be detected in the crude reaction mixture nor in any of the fractions obtained by SEC. The isolated yellowish solid, which was not identified as the target compound, was a dimer formed from the starting compound 15.[7]
4.5.3 Synthesis of dendrimers by means of the dual-protecting-group