Block Copolymers by DCC-Coupling

DCC-Coupling – General Procedure for the Preparation of PEGn-OPEm-PEGn Block Copolymers

2 - 3 Eq. α-methoxy-ω-carboxy poly(ethylene glycol), 0.4 eq. 4-(dimethylamino)pyridine and 3 eq. dicyclohexylcarbodiimide were dissolved in dry dichloromethane at 0 °C. The reactants were stirred for 10 min, followed by addition of HO-OPEm-OH. The reaction was stirred for 1-3 days until thin layer chromatography confirmed complete conversion of the alcohol. The colorless precipitate was filtered off over a syringe filter. The solvent was removed, yielding the crude product. Further product purification steps are described in detail in the respective procedures for the individual components as follows.

MeOPEG750-OPE10

See also general procedure for DCC-coupling. MeOPEG750-COOH (17 mg, 22 µmol), 4-(dimethylamino)pyridine (0.4 mg, 3.3 µmol) and dicyclohexylcarbodiimide (7 mg, 33 µmol) were reacted with HO-OPE10 (40 mg, 11 µmol) in 3 mL of dichloromethane over night. The residue was layered with methanol and ultrasonicated for 10 min. The precipitate was centrifuged off and dried under vacuum. The product was obtained as a yellow solid (41 mg, 87 %).

1H NMR (400 MHz, Chloroform-d) δ (ppm) 7.04 – 6.97 (m, 18H), 6.96 (s, 1H), 6.93 (s, 1H), 4.96 (s, 2H), 3.97 – 3.81 (m, 40H), 3.70 – 3.43 (m, PEG-backbone), 3.38 (s, 3H), 3.32 (s, 1H), 2.74 (t, J = 7.1 Hz, 2H), 2.53 (t, J = 7.0 Hz, 2H), 1.81 (dt, J = 12.1, 5.9 Hz, 20H), 1.70 – 1.21 (m, 160H), 1.05 – 0.84 (m, 120H).

MeOPEG2000-OPE10

See also general procedure for DCC-coupling. MeOPEG2000-COOH (33 mg, 16 µmol), 4-(dimethylamino)pyridine (0.5 mg, 4.4 µmol) and dicyclohexylcarbodiimide (4.5 mg, 22 µmol) were reacted with HO-OPE10 (40 mg, 11 µmol) in 3 mL of dichloromethane over night. The

Experimental Section

residue was layered with methanol and ultrasonicated for 10 min. The precipitate was centrifuged off and dried under vacuum. The product was obtained as a yellow solid (45 mg, 73 %).

1H NMR (400 MHz, Chloroform-d) δ (ppm) 6.99 – 6.94 (m, 18H), 6.94 (s, 1H), 6.91 (s, 1H), 4.93 (s, 2H), 3.95 – 3.79 (m, 40H), 3.70 – 3.38 (m, PEG-backbone), 3.36 (s, 3H), 3.31 (s, 1H), 2.71 (t, J = 7.0 Hz, 2H), 2.51 (t, J = 7.0 Hz, 2H), 1.84 – 1.70 (m, 20H), 1.67 – 1.17 (m, 160H), 1.01 – 0.80 (m, 120H).

PEG2000-OPE7-PEG2000

See also general procedure for DCC-coupling. MeOPEG2000-COOH (32 mg, 16 µmol), 4-(dimethylamino)pyridine (0.4 mg, 4 µmol) and dicyclohexylcarbodiimide (4.7 mg, 23 µmol) were reacted with HO-OPE7-OH (20 mg, 8 µmol) in 2 mL of dichloromethane overnight. The white precipitate was filtered off over a syringe filter, the solvent was removed and the product was obtained as a yellow solid (30 mg, 56 %).

1H NMR (400 MHz, Chloroform-d) δ (ppm) 7.04 – 6.95 (m, 10H), 6.94 (s, 2H), 6.92 (s, 2H), 4.94 (s, 4H), 3.99 – 3.78 (m, 28H), 3.74 – 3.50 (m, PEG2000-backbone), 3.36 (s, 6H), 2.72 (t, J = 7.0 Hz, 4H), 2.51 (t, J = 6.9 Hz, 4H), 1.85 – 1.71 (m, 14H), 1.71 – 1.18 (m, 112H), 1.00 – 0.75 (m, 84H).

MeOPEG750-OPE9-PEG750OMe

See also general procedure for DCC-coupling. MeOPEG750-COOH (28 mg, 38 µmol), 4-(dimethylamino)pyridine (1.2 mg, 10 µmol) and dicyclohexylcarbodiimide (9.3 mg, 45 µmol) were reacted with HO-OPE9-OH (50 mg, 15 µmol) in 3 mL of dichloromethane over night. The white precipitate was filtered off over a syringe filter and the solvent was removed. The residue was layered with methanol and ultrasonicated for 10 min. The precipitate was centrifuged off and dried under vacuum. The product was obtained as a yellow solid (34 mg, 47 %).

1H NMR (400 MHz, Chloroform-d) δ (ppm) 7.04 – 6.97 (m, 14H), 6.96 (s, 2H), 6.93 (s, 2H), 4.96 (s, 4H), 3.97 – 3.80 (m, 36H), 3.71 – 3.42 (m, PEG-backbone), 3.38 (s, 6H), 2.74 (t, J = 7.0

Experimental Section

Hz, 4H), 2.53 (t, J = 7.0 Hz, 4H), 1.87 – 1.74 (m, 18H), 1.72 – 1.19 (m, 144H), 1.04 – 0.83 (m, 108H).

PEG2000-OPE9-PEG2000

See also general procedure for DCC-coupling. MeOPEG2000-COOH (164 mg, 82 µmol), 4-(dimethylamino)pyridine (1.3 mg, 11 µmol) and dicyclohexylcarbodiimide (22.5 mg, 109 µmol) were reacted with HO-OPE9-OH (90 mg, 27 µmol) in 3 mL of dichloromethane overnight. The residue was dissolved in dichloromethane and washed with water. The organic layer was dried over magnesium sulfate and the solvent was removed. PEG2000-OPE9-PEG2000 was obtained as a yellow solid (185 mg, 94 %).

1H NMR (400 MHz, Chloroform-d) δ (ppm) 7.02 – 6.97 (m, 14H), 6.95 (s, 2H), 6.93 (s, 2H), 4.96 (s, 4H), 3.95 – 3.85 (m, 36H), 3.71 – 3.40 (m, PEG2000-backbone), 3.38 (s, 6H), 2.74 (t, J = 7.4 Hz, 4H), 2.53 (t, J = 7.1 Hz, 4H), 1.86 – 1.74 (m, 18H), 1.73 – 1.21 (m, 144H), 1.01 – 0.83 (m, 108H).

Biotin-PEG2000-OPE9-PEG2000-Biotin

See also general procedure for DCC-coupling. Biotin-PEG2000-COOH (40 mg, 20 µmol), 4-(dimethylamino)pyridine (0.4 mg, 3.6 µmol) and dicyclohexylcarbodiimide (5.6 mg, 27 µmol) were reacted with HO-OPE9-OH (30 mg, 9 µmol) in 3 mL of dichloromethane over night. The residue was dissolved in methanol and ultrasonicated for 10 min. Under liquid nitrogen cooling the polymer precipitated and was centrifuged off and dried under vacuum. Biotin-PEG2000-OPE9 -PEG2000-Biotin was obtained as a yellow solid (17 mg, 26 %).

1H NMR (400 MHz, Chloroform-d) δ 7.02 – 6.96 (m, 14H), 6.95 (s, 2H), 6.92 (s, 2H), 6.57 (s, 2H), 5.54 (s, 2H), 4.97 (s, 4H), 4.55 – 4.46 (m, 2H), 4.37 – 4.29 (m, 2H), 3.98 – 3.79 (m, 36H), 3.78 – 3.35 (m, PEG2000-backbone), 3.20 – 3.11 (m, 2H), 2.96 – 2.88 (m, 2H), 2.76 – 2.73 (m, 4H), 2.73 – 2.67 (m, 2H), 2.63 – 2.49 (m, 4H), 2.27 – 2.16 (m, 4H), 1.87 – 1.75 (m, 18H), 1.74 – 1.22 (m, 130H), 1.04 – 0.79 (m, 108H).

Experimental Section

PEG2000-OPE11-PEG2000

See also general procedure for DCC-coupling. MeOPEG2000-COOH (44 mg, 22 µmol), 4-(dimethylamino)pyridine (0.5 mg, 4 µmol) and dicyclohexylcarbodiimide (5 mg, 25 µmol) were reacted with HO-OPE11-OH (40 mg, 10 µmol) in 3 mL of dichloromethane over night. The white precipitate was filtered off over a syringe filter, the solvent was removed and the product was 4-(dimethylamino)pyridine (0.4 mg, 3.4 µmol) and dicyclohexylcarbodiimide (5 mg, 25 µmol) were reacted with HO-OPE9-DPP-OH (30 mg, 8.6 µmol) in 3 mL of dichloromethane over night. The white precipitate was filtered off over a syringe filter and the solvent was removed. The residue was layered with methanol and ulrasonicated for 10 min. The precipitate was centrifuged off and dried under vacuum. PEG2000-OPE9-DPP-PEG2000 was obtained as a red solid (53 mg, 82 %).

1H NMR (400 MHz, Chloroform-d) δ (ppm) 7.78 (d, J = 8.1 Hz, 4H), 7.56 (d, J = 7.8 Hz, 4H), 4-(dimethylamino)pyridine (0.3 mg, 2.5 µmol) and dicyclohexylcarbodiimide (2 mg, 10 µmol) were reacted with HO-OPE21-OH (30 mg, 4 µmol) in 3 mL of dichloromethane over night. The residue was layered with methanol and sonicated for 10 min. The precipitate was centrifuged off and dried under vacuum. PEG750-OPE21-PEG750 was obtained as a yellow solid (33 mg, 97 %).

Experimental Section

1H NMR (400 MHz, Chloroform-d) δ (ppm) 7.03 – 6.97 (m, 38H), 6.96 (s, 2H), 6.93 (s, 2H), 4.96 (s, 4H), 3.97 – 3.84 (m, 84H), 3.68 – 3.43 (m, PEG750-backbone), 3.38 (s, 6H), 2.74 (t, J = 7.0 Hz, 4H), 2.53 (t, J = 7.2 Hz, 4H), 1.88 – 1.74 (m, 42H), 1.70 – 1.22 (m, 336H), 1.04 – 0.84 (m, 252H).

PEG2000-OPE21-PEG2000

See also general procedure for DCC-coupling. MeOPEG2000-COOH (20 mg, 10 µmol), 4-(dimethylamino)pyridine (0.3 mg, 2.5 µmol) and dicyclohexylcarbodiimide (2 mg, 10 µmol) were reacted with HO-OPE21-OH (30 mg, 4 µmol) in 3 mL of dichloromethane over night. The residue was layered with methanol and sonicated for 10 min. The precipitate was centrifuged off and dried under vacuum. PEG2000-OPE21-PEG2000 was obtained as a yellow solid (35 mg, 80 %).

1H NMR (400 MHz, Chloroform-d) δ (ppm) 7.04 – 6.96 (m, 38H), 6.96 (s, 2H), 6.93 (s, 2H), 4.96 (s, 4H), 3.99 – 3.81 (m, 84H), 3.71 – 3.43 (m, PEG2000-backbone), 3.38 (s, 6H), 2.74 (t, J = 6.9 Hz, 4H), 2.53 (t, J = 7.1 Hz, 4H), 1.87 – 1.74 (m, 42H), 1.74 – 1.20 (m, 336H), 1.04 – 0.83 (m, 252H).

PEG5000-OPE21-PEG5000

See also general procedure for DCC-coupling. MeOPEG5000-COOH (50 mg, 10 µmol), 4-(dimethylamino)pyridine (0.3 mg, 2.5 µmol) and dicyclohexylcarbodiimide (2 mg, 10 µmol) were reacted with HO-OPE21-OH (30 mg, 4 µmol) in 3 mL of dichloromethane over night. The residue was dissolved in methanol and sonicated for 10 min. Under liquid nitrogen cooling the polymer precipitated and was centrifuged off and dried under vacuum. PEG5000-OPE21-PEG5000 was obtained as a yellow solid (15 mg, 22 %).

1H NMR (400 MHz, Chloroform-d) δ (ppm) 7.03 – 6.96 (m, 38H), 6.96 (s, 2H), 6.93 (s, 2H), 4.96 (s, 4H), 4.01 – 3.81 (m, 84H), 3.76 – 3.41 (m, PEG5000-backbone), 3.38 (s, 6H), 2.78 – 2.72 (m, 4H), 2.57 – 2.48 (m, 4H), 1.87 – 1.73 (m, 42H), 1.69 – 1.18 (m, 336H), 1.04 – 0.80 (m, 252H).

Experimental Section

PEG5000-OPE31-PEG5000

See also general procedure for DCC-coupling. MeOPEG5000-COOH (10 mg, 2 µmol), 4-(dimethylamino)pyridine (40 µg, 0.3 µmol) and dicyclohexylcarbodiimide (0.5 mg, 2.4 µmol) were reacted with HO-OPE31-OH (9 mg, 0.8 µmol) in 1 mL of dichloromethane overnight. The residue was layered with methanol and sonicated for 10 min. Under liquid nitrogen cooling the polymer precipitated and was centrifuged off and dried under vacuum. PEG5000-OPE31-PEG5000

was obtained as a yellow solid (4 mg, 24 %). 4-(dimethylamino)pyridine (20 µg, 0.1 µmol) and dicyclohexylcarbodiimide (0.2 mg, 1 µmol) were reacted with HO-OPE43-OH (5.5 mg, 0.4 µmol) in 1 mL of dichloromethane overnight. The residue was layered with methanol and sonicated for 10 min. Under liquid nitrogen cooling the polymer precipitated and was centrifuged off and dried under vacuum. PEG5000-OPE43-PEG5000

was obtained as a yellow solid (3 mg, 44 %).

1H NMR (400 MHz, Chloroform-d) δ (ppm) 7.01 – 6.87 (m, 84H), 6.87 (s, 2H), 4.89 (s, 4H), 4.02 – 3.71 (m, 172H), 3.69 – 3.34 (m, PEG5000-backbone), 3.31 (s, 6H), 2.71 – 2.64 (m, 4H), 2.51 – 2.43 (m, 4H), 1.81 – 1.68 (m, 86H), 1.68 – 1.11 (m, 688H), 0.97 – 0.71 (m, 516H).

8.3.7 Block Copolymers by Sonogashira Coupling

D-OPE9-D

Dendron 15 (86 mg, 109 µmol) and OPE9 (117 mg, 36 µmol) were dissolved in 2 mL of tetrahydrofuran and 1 mL of piperidine and degassed with four freeze-pump-thaw cycles. After addition of [Pd(PPh3)2Cl2] (0.25 mg, 0.36 µmol) and copper iodide (0.13 mg, 0.72 µmol), the mixture was degassed with three freeze-pump-thaw cycles. The reaction mixture was stirred for 18

Experimental Section

h at 45°C. Byproducts were filtered off over a syringe filter and the solvent was removed under reduced pressure. The yellow solid was layered with methanol and ultrasonicated for 15 min. The product was purified from its Glaser byproduct by dissolving in tetrahydrofuran and precipitation in ethyl acetate.

1H NMR (400 MHz, THF-d8) δ (ppm) 8.52 – 8.36 (m, 2H), 7.96 (d, J = 7.1 Hz, 4H), 7.54 (d, J

= 7.0 Hz, 4H), 7.10 (s, 2H), 7.08 – 6.99 (m, 14H), 6.91 (s, 2H), 4.99 (s, 2H), 4.22 – 4.07 (m, 8H), 4.00 – 3.34 (m, 30H), 1.90 – 1.21 (m, 162H), 1.10 – 0.79 (m, 108H).

D-OPE10

Dendron 15 (44 mg, 55 µmol) and HO-OPE10 (40 mg, 11 µmol) were dissolved in 2 mL of tetrahydrofuran and 1 mL of piperidine and degassed with four freeze-pump-thaw cycles. After addition of [Pd(PPh3)2Cl2] (0.08 mg, 0.11 µmol) and copper iodide (0.04 mg, 0.22 µmol), the mixture was degassed with three freeze-pump-thaw cycles. The reaction was stirred for 2 days at 45 °C. Byproducts were filtered off over a syringe filter and the solvent was removed under reduced pressure. The residue was dissolved in dichloromethane and the product was precipitated in methanol and centrifuged off.

1H NMR (400 MHz, Chloroform-d) δ (ppm) 8.29 – 8.07 (m, 1H), 7.86 (d, J = 6.9 Hz, 2H), 7.59 (d, J = 7.1 Hz, 2H), 7.07 – 6.95 (m, 18H), 6.93 (s, 2H), 5.13 – 4.95 (m, 1H), 4.53 (s, 2H), 4.26 – 4.07 (m, 2H), 4.03 – 3.80 (m, 40H), 3.78 – 3.31 (m, 32H), 1.88 – 1.72 (m, 20H), 1.72 – 1.17 (m, 160H), 0.93 (m, 120H).

Experimental Section