A 250 mL cylindrical glass vessel equipped with a coarse glass frit was charged with 4-amino-N-[(9H-fluoren-9-ylmethoxy)carbonyl]-L-phenylalanine on Wang resin (10 g) obtained in Example 36 and a solution prepared from quinoline-4-carboxylic acid (5.2 g, 30 mmol), BOP (13.75 g, 30 mmol) and diisopropylethylamine (6.8 mL) in 70 mL of NMP. The slurry was agitated for 4 hours. The mixture was filtered and washed with dichloromethane (2×100 mL), methanol (2×100 mL) and dimethylformamide (2×100 mL). To the washed resin was added a solution of 25% piperidine in NMP (80 mL), the mixture was agitated at room temperature for 20 minutes and filtered. The process was repeated and the resulting slurry was filtered and washed with dichloromethane (2×100 mL), methanol (2×100 mL) and dimethylformamide (2×100 mL). Filtration afforded 4-[[(4-quinolinyl)carbonyl]amino]-L-phenylalanine on Wang resin suitable for use in the next step.
