Example 22
Polymer 21 (100 mg, 0.165 mmol) was ground into a fine powder and mixed with DMF (10 mL) for 20 minutes. Fmoc-Val-OH (0.167 g, 0.494 mmol), HBTU (0.187 g, 0.494 mmol), EDC (95 mg, 0.494 mmol) and DIPEA (0.064 mL, 0.494 mmol) were added to a filtration column tube and sealed. A lab rotor was used to facilitate mixing overnight. The solid was filtered and washed with DCM (5×20 mL) and methanol (5×20 mL). The resulting product was dried to provide Polymer 22-a as an off-white powder. Weight=0.0603 g. A positive Kaiser test result indicated presence of unreacted amine.
Polymer 22-a (60 mg) was placed in a solution of piperidine: DMF (20:80 v/v), (20 mL) and stirred for 1 hour, after which the solid was filtered and washed with ethanol (3×50 mL) and DCM (3×50 mL). This process was then repeated, and the product was dried to provide Polymer 22 as an off-white powder. Weight=0.0553 g (48% yield). A positive Kaiser test result indicated presence of free amine. FTIR: Peaks at 3300 (N—H/O—H), 2850 (C—H), 1748 (amide), 1648 (C═O, amide of coupled product), 1585 (C═O of CMC), 1453/1403/1024/1095/1058, 961, 841.
