1: sodium tetrahydroborate / methanol / -78 - -30 °C 2: thionyl chloride; pyridine / dichloromethane / 5 h / 0 - 20 °C 3: diisobutylaluminium hydride / dichloromethane; hexane / 1.5 h / -78 - 0 °C 4: Dess-Martin periodane; pyridine / dichloromethane / 1 h / 0 - 20 °C View Scheme

1.1: BuLi / hexane; tetrahydrofuran / -78 - 20 °C 1.2: hexane; tetrahydrofuran / 2 h / Heating 2.1: LiAlH4 / tetrahydrofuran / 0 °C 3.1: ClCOCOCl; DMSO; Et3N / CH2Cl2 / 2.25 h / -78 - 20 °C View Scheme