Rink-amide-resin (loading: 0.43 mmol/g, 6.66 g, 2.86 mmol) was swelled with dichloromethane (50 ml). The solvent was removed. A 20% solution of piperidine in N-methylpyrrolidinone was added (50 ml). The reactor was shaken for 20 min. The liquid was removed. The resin was washed with N-methylpyrrolidinone (3×50 ml) and dichloromethane (5×50 ml). A solution of BOC-Lys(FMOC)-OH (5.37 g, 11.5 mmol) in N-methylpyrrolidinone (50 ml) and a solution of 1-hydroxybenzotriazole (1.75 g, 11.5 mmol) in N-methylpyrrolidinone (20 ml) were added successively. Diisopropylcarbodiimide (1.79 ml, 11.5 mmol) and ethyldiisopropylamine (1.96 ml, 11.5 mmol) were added. The reactor was shaken at room temperature for 16 h. The liquid was removed. The resin was washed with N-methylpyrrolidinone (3×50 ml) and dichloromethane (3×50 ml). A solution of 4-acetylbenzoic acid (2.82 g, 11.5 mmol) in N-methylpyrrolidinone (50 ml) and a solution of 1-hydroxybenzotriazole (1.75 g, 11.5 mmol) in N-methylpyrrolidinone (20 ml) were added successively. Diisopropylcarbodiimide (1.79 ml, 11.5 mmol) and ethyldiisopropylamine (1.96 ml, 11.5 mmol) were added. The reactor was shaken at room temperature for 16 h. The resin was washed with N-methylpyrrolidinone (3×50 ml) and dichloromethane (3×50 ml). A solution of 50% of trifluoroacetic acid and 10% triisopropylsilane in dichloromethane (50 ml) was added to the resin. The reaction vessel was shaken for 1 h at room temperature. The liquid was collected. The solvent was removed in vacuo. The residue was redissolved in toluene (50 ml). The solvent was removed in vacuo.
