1: 80 percent / sodium hydroxide / ethanol; H2O / 3 h / 0 °C 2: 19.3 g / toluene / 5 h / Heating 3: 28 percent / Bacillus licheniformis subtilisin; NH3 / H2O; dimethylformamide / 3 h / 38 °C / pH 8 4: HCl / dioxane / 2 h / 0 °C 5: 494 mg / trietylamine / dimethylformamide / 5 h / 0 °C / pH 8 View Scheme

1: 80 percent / sodium hydroxide / ethanol; H2O / 3 h / 0 °C 2: 19.3 g / toluene / 5 h / Heating 3: 29 percent / Bacillus licheniformis subtilisin; NH3 / H2O; dimethylformamide / 3 h / 38 °C / pH 8 4: 100 percent / sodium hydroxide / ethanol; H2O / 0 °C 5: HCl / dioxane / 2 h / 0 °C 6: 1.71 g / triethylamine / dimethylformamide / 5 h / 0 °C / pH 8 View Scheme