potassium carbonate in dichloromethane T=20°C; 18 h;

1.1: 98 percent / NaIO4 / methanol; H2O / 0 - 20 °C 2.1: t-BuOK / tetrahydrofuran / 0.33 h / -78 °C 2.2: 80 percent / tetrahydrofuran / -78 - 20 °C View Scheme