hydrogenchloride in methanol T=20°C; Ring cleavage;

1.1: Zn-Cu; POCl3 / diethyl ether / 4 h / 20 °C / Heating 2.1: Zn; AcOH / 2.5 h / 20 - 120 °C 3.1: 82.5 percent / p-TsOH / benzene / 20 h / 120 °C 4.1: BuLi / hexane; tetrahydrofuran / 0.5 h / -70 °C 4.2: B(OiPr)3 / tetrahydrofuran; hexane / -70 - 20 °C 4.3: 83 percent / H2SO4 / H2O / 0.5 h / 0 °C 5.1: 79 percent / HCl / methanol / 20 °C View Scheme

1.1: 82.5 percent / p-TsOH / benzene / 20 h / 120 °C 2.1: BuLi / hexane; tetrahydrofuran / 0.5 h / -70 °C 2.2: B(OiPr)3 / tetrahydrofuran; hexane / -70 - 20 °C 2.3: 83 percent / H2SO4 / H2O / 0.5 h / 0 °C 3.1: 79 percent / HCl / methanol / 20 °C View Scheme

1.1: Zn; AcOH / 2.5 h / 20 - 120 °C 2.1: 82.5 percent / p-TsOH / benzene / 20 h / 120 °C 3.1: BuLi / hexane; tetrahydrofuran / 0.5 h / -70 °C 3.2: B(OiPr)3 / tetrahydrofuran; hexane / -70 - 20 °C 3.3: 83 percent / H2SO4 / H2O / 0.5 h / 0 °C 4.1: 79 percent / HCl / methanol / 20 °C View Scheme

1.1: BuLi / hexane; tetrahydrofuran / 0.5 h / -70 °C 1.2: B(OiPr)3 / tetrahydrofuran; hexane / -70 - 20 °C 1.3: 83 percent / H2SO4 / H2O / 0.5 h / 0 °C 2.1: 79 percent / HCl / methanol / 20 °C View Scheme