1.1: 80.4 percent / m-CPBA / CHCl3 / 4 h / 20 °C 2.1: acetic anhydride / 3 h / 100 °C 2.2: 84 percent / conc. HCl / tetrahydrofuran / 48 h / 25 °C 3.1: 80 percent / Et3N / tetrahydrofuran / 8 h / 0 - 20 °C 4.1: butyllithium / tetrahydrofuran; hexane / 1 h / -78 °C 4.2: tetrahydrofuran; hexane / 4 h / -78 °C 5.1: 90 percent / aq. HCl / acetonitrile / 36 h / 20 °C 6.1: 65 percent / aq. NaOH / 6 h / Heating View Scheme