1.1: n-BuLi; diisopropylamine / tetrahydrofuran; hexane / 0.5 h / -15 - 0 °C 1.2: tetrahydrofuran; hexane / 0.5 h / -15 - 20 °C 2.1: MCPBA / hexane / 4 h / 20 °C 2.2: 0.8 g / Et3N*3HF / CH2Cl2 / 2 h / 20 °C 3.1: 88 percent / Dess-Martin periodinane / CH2Cl2 / 1 h / 20 °C 4.1: pyrrolidone hydrotribromide / tetrahydrofuran / 1 h / 20 °C 4.2: 71 percent / LiBr; Li2CO3 / dimethylformamide / 2 h / Heating View Scheme