1: 36 percent / α-chymotrypsin, NH4OAc, pH 6.9, 1 M NH4OH / dimethylformamide; H2O / 2 h / Ambient temperature 2: 85 percent / 5M HCl / 3.5 h / Heating View Scheme

1.1: acetic anhydride / 3 h / 100 °C 1.2: 84 percent / conc. HCl / tetrahydrofuran / 48 h / 25 °C 2.1: 80 percent / Et3N / tetrahydrofuran / 8 h / 0 - 20 °C 3.1: butyllithium / tetrahydrofuran; hexane / 1 h / -78 °C 3.2: tetrahydrofuran; hexane / 4 h / -78 °C 4.1: 90 percent / aq. HCl / acetonitrile / 36 h / 20 °C 5.1: 65 percent / aq. NaOH / 6 h / Heating View Scheme

1.1: 80 percent / Et3N / tetrahydrofuran / 8 h / 0 - 20 °C 2.1: butyllithium / tetrahydrofuran; hexane / 1 h / -78 °C 2.2: tetrahydrofuran; hexane / 4 h / -78 °C 3.1: 90 percent / aq. HCl / acetonitrile / 36 h / 20 °C 4.1: 65 percent / aq. NaOH / 6 h / Heating View Scheme

1: 90 percent / aq. HCl / acetonitrile / 36 h / 20 °C 2: 65 percent / aq. NaOH / 6 h / Heating View Scheme

1.1: butyllithium / tetrahydrofuran; hexane / 1 h / -78 °C 1.2: tetrahydrofuran; hexane / 4 h / -78 °C 2.1: 90 percent / aq. HCl / acetonitrile / 36 h / 20 °C 3.1: 65 percent / aq. NaOH / 6 h / Heating View Scheme

hydrogenchloride; water in ethanol Reflux;

sodium hydroxide 6 h; Heating; Yield given;

1: 1.) lithium diisopropylamide, lithium chloride / 1) hexane, THF, 0 deg C, 20 min; 2) THF, hexane, -78 deg C, 3 h, -45 deg C, 3 h 2: aq. NaOH / 6 h / Heating View Scheme