1: 76 percent / lipase / diethyl ether / 6 h / Ambient temperature 2: 74 percent / Et3N, 4-DMAP / CH2Cl2 / 3 h / Ambient temperature 3: 35 percent / NaBH4 / dimethylsulfoxide / 12 h / 60 °C 4: 54 percent / CrO3, H2SO4 / acetone / 0.5 h / 0 °C View Scheme