1.1: LDA; HMPA / tetrahydrofuran / -78 °C 1.2: 100 percent / 5 h / -78 - 0 °C 2.1: 62 percent / Ph3P; H2O / tetrahydrofuran / 20 h / 20 °C 3.1: 91 percent / NaOMe / methanol / Heating View Scheme

1.1: n-BuLi; diisopropylamine / tetrahydrofuran; hexane / 1 h / -78 °C 1.2: 74 percent / tetrahydrofuran; hexane / 25 h / -78 - 20 °C 2.1: 73 percent / NaH / dimethylsulfoxide / 3 h / 55 °C 3.1: 65 percent / aq. H2SO4 / tetrahydrofuran / 6 h / Heating View Scheme