Bioconjugate Chemistry
Page 20 of 34
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.43 Hz, 1H), 5.60 (d, J = 1.67 Hz, 1H), 4.14 (t, J = 3.57 Hz, 2H), 3.74 (t, J = 6.51 Hz, 4H), 3.57
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(t, J = 5.54 Hz, 2H), 1.98 (s, 3H). C NMR (75 MHz, CDCl , ppm): δ 167.2, 136.1, 125.2, 70.0,
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69.4, 65.1, 61.3, 17.9.
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Synthesis of acrylateꢀtethering camptothecin (ACPT).
Camptothecin (2.0 g, 6.0 mmol) and TEA (1.01 g, 10.0 mmol) were dissolved in chloroform
o
(350 mL). The mixture was stirred at 0 C for 20 minutes, and then acryloyl chloride (0.594 g,
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.6 mmol) in 20 mL of chloroform was added dropwise. The reaction was kept at room
temperature for 24 hours. The reaction mixture was concentrated and the crude product was
purified by column chromatography using a mixed eluent of nꢀhexane/ethyl acetate (1:1, v/v) to
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give the product (1.6 g, yield: 80%). H NMR (300 MHz, CDCl , δ, ppm): 8.40 (m, 1H), 8.21
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(m, 1H), 7.94 (m, 1H), 7.82 (m, 1H), 7.67 (m, 1H), 7.23 (m, 1H), 6.52 (d, J = 1.78 Hz, 1H) and
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.98 (d, J = 1.64 Hz, 1H), 6.27 (dd, 1H), 5.71 and 5.43 (m, 2H), 5.29 (m, 2H), 2.4~2.1 (m, 2H),
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1.01(t, J = 2.96 Hz, 3H). C NMR (75 MHz, CDCl , ppm): δ 167.5, 166.5, 156.9, 152.7, 148.9,
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45.8, 145.3, 131.9, 131.3, 130.4, 129.0, 128.4, 128.2, 127.9, 127.3, 126.6, 119.9, 97.5, 76.3,
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5.4, 53.7, 31.9, 7.9. MS: [MꢀH ] = 403.12, found at 403.1286.
Synthesis of methacrylate of lipoic acid (HEMAꢀLA).
Hydroxyethyl methacrylate (1.31 g, 0.01 mol), DMAP (0.6 g, 0.005 mmol) and DCC (3.84 g,
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.02 mol) were dissolved in dichloromethane (70 mL). Lipoic acid (2.06 g, 0.01 mol) in 10 mL
of dichloromethane was added dropwise into the mixture at room temperature, and the solution
was stirred for 12 hours. The reaction mixture was then concentrated and the crude product was
purified by column chromatography using a mixed eluent of nꢀhexane/ethyl acetate (4:1, v/v) to
give the product (2.23 g, yield: 70.1%). The monomer is not stable at room temperature, and it
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should be stored at low temperature (ꢀ20 C). H NMR (300 MHz, CDCl , δ, ppm): 6.14 (d, J =
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