benzotriazol-1-ol; dicyclohexyl-carbodiimide in tetrahydrofuran T=20°C;

sodium hydroxide in methanol 1 h; Yield given;

1: H2O 2: aq. NaOH / tetrahydrofuran 3: 1.) Et3N, DPP-Cl, 2.) Et3N / 1.) EtOAc, 0 deg C, 1 h, 2.) EtOAc, overnight 4: 4 N HCl / dioxane / 2 h 5: HOBt, EDC*HCl / dimethylformamide 6: 4 N HCl / CH2Cl2; dioxane / 3 h 7: 1.) Et3N, DPP-Cl, 2.) Et3N / 1.) EtOAc, 0 deg C, 1 h, 2.) EtOAc, overnight 8: 1 N NaOH / methanol / 1 h View Scheme

1: 1.) Et3N, DPP-Cl, 2.) Et3N / 1.) EtOAc, 0 deg C, 1 h, 2.) EtOAc, overnight 2: 4 N HCl / dioxane / 2 h 3: HOBt, EDC*HCl / dimethylformamide 4: 4 N HCl / CH2Cl2; dioxane / 3 h 5: 1.) Et3N, DPP-Cl, 2.) Et3N / 1.) EtOAc, 0 deg C, 1 h, 2.) EtOAc, overnight 6: 1 N NaOH / methanol / 1 h View Scheme

1: aq. NaOH / tetrahydrofuran 2: 1.) Et3N, DPP-Cl, 2.) Et3N / 1.) EtOAc, 0 deg C, 1 h, 2.) EtOAc, overnight 3: 4 N HCl / dioxane / 2 h 4: HOBt, EDC*HCl / dimethylformamide 5: 4 N HCl / CH2Cl2; dioxane / 3 h 6: 1.) Et3N, DPP-Cl, 2.) Et3N / 1.) EtOAc, 0 deg C, 1 h, 2.) EtOAc, overnight 7: 1 N NaOH / methanol / 1 h View Scheme

1: 1.) Et3N, DPP-Cl, 2.) Et3N / 1.) EtOAc, 0 deg C, 1 h, 2.) EtOAc, overnight 2: 1 N NaOH / methanol / 1 h View Scheme

1: HOBt, EDC*HCl / dimethylformamide 2: 4 N HCl / CH2Cl2; dioxane / 3 h 3: 1.) Et3N, DPP-Cl, 2.) Et3N / 1.) EtOAc, 0 deg C, 1 h, 2.) EtOAc, overnight 4: 1 N NaOH / methanol / 1 h View Scheme

1: 4 N HCl / dioxane / 2 h 2: HOBt, EDC*HCl / dimethylformamide 3: 4 N HCl / CH2Cl2; dioxane / 3 h 4: 1.) Et3N, DPP-Cl, 2.) Et3N / 1.) EtOAc, 0 deg C, 1 h, 2.) EtOAc, overnight 5: 1 N NaOH / methanol / 1 h View Scheme

1: 4 N HCl / CH2Cl2; dioxane / 3 h 2: 1.) Et3N, DPP-Cl, 2.) Et3N / 1.) EtOAc, 0 deg C, 1 h, 2.) EtOAc, overnight 3: 1 N NaOH / methanol / 1 h View Scheme