1.1: sodium hydride / tetrahydrofuran; mineral oil / 0.25 h / -10 °C 1.2: 16 h / -10 °C 2.1: lithium borohydride / tetrahydrofuran / 16 h / 20 °C 3.1: dimethyl sulfoxide / 16 h / 60 °C 4.1: phosphoric acid / methanol / 24 h / 20 °C View Scheme