1.1: DIBAL-H / hexane / 50 h / 20 °C 1.2: NBS / 6 h / -20 °C 2.1: t-BuLi / diethyl ether / -80 - -20 °C 2.2: 29 percent / (PhSO2)2S / diethyl ether / 6.5 h / -80 - 20 °C 3.1: 26 percent / aq. TBAF / tetrahydrofuran / 1.5 h View Scheme