tetrabutyl ammonium fluoride in tetrahydrofuran T=20°C;

1: 3-dibromomethylene-hexa-1,4-diyne With n-butyllithium in hexane; toluene T=-20 - 0°C; Fritsch-Buttenberg-Wiechell rearrangement; 2: oxirane With ammonia in tetrahydrofuran; hexane; toluene T=-20 - 20°C; Further stages.;

1.1: BaMnO4 / CH2Cl2 / 20 °C 2.1: PPh3 / CH2Cl2 / 0.5 h / 0 °C 2.2: 542 mg / CH2Cl2 / 0.5 h / 0 °C 3.1: 76 percent / BuLi / hexane / 1 h / -78 - 20 °C 4.1: 96 percent / TBAF / tetrahydrofuran / 20 °C View Scheme

1: 76 percent / BuLi / hexane / 1 h / -78 - 20 °C 2: 96 percent / TBAF / tetrahydrofuran / 20 °C View Scheme

1.1: 76 percent / BaMnO4 / CH2Cl2 / 20 °C 2.1: BuLi / tetrahydrofuran; hexane / 2 h / -20 °C 2.2: 76 percent / tetrahydrofuran; hexane / -20 - 20 °C 3.1: BaMnO4 / CH2Cl2 / 20 °C 4.1: PPh3 / CH2Cl2 / 0.5 h / 0 °C 4.2: 542 mg / CH2Cl2 / 0.5 h / 0 °C 5.1: 76 percent / BuLi / hexane / 1 h / -78 - 20 °C 6.1: 96 percent / TBAF / tetrahydrofuran / 20 °C View Scheme

1.1: BuLi / tetrahydrofuran; hexane / 2 h / -20 °C 1.2: 76 percent / tetrahydrofuran; hexane / -20 - 20 °C 2.1: BaMnO4 / CH2Cl2 / 20 °C 3.1: PPh3 / CH2Cl2 / 0.5 h / 0 °C 3.2: 542 mg / CH2Cl2 / 0.5 h / 0 °C 4.1: 76 percent / BuLi / hexane / 1 h / -78 - 20 °C 5.1: 96 percent / TBAF / tetrahydrofuran / 20 °C View Scheme

(i) aq. HCl, (ii) KOH, aq. MeOH, (iii) CuCl, NH2OH*HCl, EtNH2; Multistep reaction;