1: 60 percent / triethylamine, 1-hydroxybenzotriazole (HOBT), dicyclohexylcarbodiimide (DCC) / tetrahydrofuran; CHCl3 / a) 0 deg C, 1 h, b) RT, overnight 2: 80 percent / 1 N NaOH / methanol / a) 0 deg C, 1 h, b) RT, 20 h 3: 90 percent / triethylamine, 1-hydroxybenzotriazole (HOBT), dicyclohexylcarbodiimide (DCC) / tetrahydrofuran; CHCl3 / a) 0 deg C, 1 h, b) RT, 20 h 4: 85 percent / 1 N NaOH / methanol / a) 0 deg C, 30 min, b) RT, 20 h 5: 90 percent / TFA, HCl / a) 0 deg C, 30 min, b) RT, 30 min View Scheme