1.1: DIBAL-H / toluene / 2 h / -78 °C 1.2: 90.7 percent / 6 h / Heating 2.1: 1M HCl / methanol / 2 h / 20 °C 3.1: LiOH / tetrahydrofuran; H2O / 8 h / 20 °C 4.1: Boc2O; Et3N / 20 °C 5.1: DMAP / toluene / 90 - 95 °C View Scheme