1.1: n-BuLi / tetrahydrofuran; hexane / -78 °C 1.2: 78 percent / tetrahydrofuran; hexane / -78 °C 2.1: n-BuLI / tetrahydrofuran; hexane / 0.5 h / -78 °C 2.2: 88 percent / tetrahydrofuran; hexane / -78 °C 3.1: 90 percent / tetrabutylammonium fluoride (TBAF) / tetrahydrofuran / 1 h / 20 °C 4.1: 81 percent / MS 4 Angstroem / Zn(OTf)2 / toluene / 3 h / 90 °C View Scheme