1.1: molecular sieves 4 Angstroem; (R)-Me-CBS; borane-dimethyl sulfide / tetrahydrofuran; toluene / -30 °C 2.1: pyridine; DMAP / 12 h 3.1: hydrogen; Lindlar catalyst / hexane / 2 h 4.1: ozone / methanol; CH2Cl2 / -78 °C 4.2: NaBH4 / methanol; CH2Cl2 / 0.25 h / -78 °C View Scheme