1: 42 percent / α-chymotrypsine; KH2PO4; Na2PO4 / NaOH / H2O / 2 h / 20 °C / pH 7.4 / Enzymatic reaction 2: AcOH; aq. HCl / 1 h / Heating 3: 80 percent / H2 / Ni Raney / ethanol / 760 Torr View Scheme

1: 96 percent / 50percent KOH / methanol / 1 h 2: SOCl2 / 1 h / Heating 3: NaN3 / H2O; acetone / 0.83 h 4: CF3COOH / CH2Cl2 / Heating 5: K2CO3 / H2O; methanol / 72 h / Ambient temperature View Scheme

1.1: 85 percent / AcOH; aq. HCl / 1 h / Heating 2.1: 21 percent / DCC; DMAP / CH2Cl2 / 20 °C 3.1: 93 percent / LiOH*H2O / tetrahydrofuran; H2O / 20 °C 4.1: H2 / Raney-Ni / methanol / 24 h / 20 °C / 3800 Torr 4.2: 91 percent / aq. HCl View Scheme

1.1: 85 percent / AcOH; aq. HCl / 1 h / Heating 2.1: 22.5 percent / DCC; DMAP / CH2Cl2 / 1 h / 20 °C 3.1: 91 percent / LiOH*H2O / tetrahydrofuran; H2O / 25 h / 20 °C 4.1: H2 / Raney-Ni / methanol / 24 h / 20 °C / 3800 Torr 4.2: 91 percent / aq. HCl View Scheme