1: diisobutylaluminium hydride / tetrahydrofuran; toluene / 20 h / -78 - 20 °C 2: hypophosphorous acid; sodium nitrite / water; acetic acid / 0 - 20 °C 3: methanol; sodium tetrahydroborate / 0.17 h / 20 °C View Scheme

thionyl chloride in dichloromethane T=0 - 20°C; 2 h;