hydrogenchloride in ethyl acetate T=20°C;

1: 91 percent / aq. NaHCO3 / tetrahydrofuran / 24 h 2: 40 percent / Cu(OAc)2; Et3N; pyridine / 4 Angstroem molecular sieves / CH2Cl2 / 20 °C 3: 86 percent / TBAF / tetrahydrofuran / 0 °C 4: 100 percent / HCl / ethyl acetate / 20 °C View Scheme

1.1: 82 percent / imidazole / CH2Cl2 / 12.5 h / 0 - 20 °C 2.1: n-BuLi / tetrahydrofuran; hexane / 0.5 h / -78 °C 2.2: triisopropyl borate / tetrahydrofuran; hexane / 5 h / -78 - 20 °C 2.3: 68 percent / aq. HCl / tetrahydrofuran; hexane / 0.5 h / 0 °C 3.1: 40 percent / Cu(OAc)2; Et3N; pyridine / 4 Angstroem molecular sieves / CH2Cl2 / 20 °C 4.1: 86 percent / TBAF / tetrahydrofuran / 0 °C 5.1: 100 percent / HCl / ethyl acetate / 20 °C View Scheme

1: 40 percent / Cu(OAc)2; Et3N; pyridine / 4 Angstroem molecular sieves / CH2Cl2 / 20 °C 2: 86 percent / TBAF / tetrahydrofuran / 0 °C 3: 100 percent / HCl / ethyl acetate / 20 °C View Scheme

1.1: n-BuLi / tetrahydrofuran; hexane / 0.5 h / -78 °C 1.2: triisopropyl borate / tetrahydrofuran; hexane / 5 h / -78 - 20 °C 1.3: 68 percent / aq. HCl / tetrahydrofuran; hexane / 0.5 h / 0 °C 2.1: 40 percent / Cu(OAc)2; Et3N; pyridine / 4 Angstroem molecular sieves / CH2Cl2 / 20 °C 3.1: 86 percent / TBAF / tetrahydrofuran / 0 °C 4.1: 100 percent / HCl / ethyl acetate / 20 °C View Scheme

1: 40 percent / Cu(OAc)2; Et3N; pyridine / 4 Angstroem molecular sieves / CH2Cl2 / 20 °C 2: 86 percent / TBAF / tetrahydrofuran / 0 °C 3: 100 percent / HCl / ethyl acetate / 20 °C View Scheme

1: 86 percent / TBAF / tetrahydrofuran / 0 °C 2: 100 percent / HCl / ethyl acetate / 20 °C View Scheme