1: 79 percent / aq. NaCl / dimethylsulfoxide / 4 h / Heating 2: 85 percent / Triton-X, 0.1 M aq. NaOH / 30 h / α-chymotrypsin 3: 1.) ethyl chloroformate, triethylamine, 2.) aq. NaN3 / 1.) acetone, from 0 deg C to 25 deg C, 55 min, 2.) acetone, 0 deg C, 2 h 4: toluene / 8 h / Heating 5: 6 N aq. HCl / 2 h / Heating View Scheme

1: 79 percent / NaCl / dimethylsulfoxide; H2O / 160 °C 2: 85 percent / 25 °C / α-chymotrypsin 3: 1) NH3, 2) bis(trifluoroacetoxy)iodobenzene / 1) MeOH, pressure, 2) DMF, H2O View Scheme

1: 79 percent / NaCl / dimethylsulfoxide; H2O / 160 °C 2: H2O; dimethylsulfoxide / porcine liver esterase View Scheme