1: With borane-THF in tetrahydrofuran T=0 - 20°C; Addition; 14 h; 2: With sodium hydroxide; dihydrogen peroxide in tetrahydrofuran; water T=0°C; Oxidation; 0.5 h;

1.1: n-BuLi; HMPA / tetrahydrofuran / -78 °C 1.2: 86 percent / tetrahydrofuran / 7.5 h / -78 - 20 °C 2.1: borane-THF complex / tetrahydrofuran / 14 h / 0 - 20 °C 2.2: 45 percent / NaOH; H2O2 / tetrahydrofuran; H2O / 0.5 h / 0 °C View Scheme