1: 44 percent / tributyltin hydride, azobisisobutyronitrile / toluene / 0.25 h / 110 °C 2: 86 percent / hydrogen fluoride-pyridine / acetonitrile / 2.5 h / Ambient temperature 3: 86 percent / porcine liver esterase, phosphate buffer solution (pH=8) / acetone / 4 h / Ambient temperature View Scheme

1: 59 percent / NaBH4 / methanol / 0.67 h / 0 °C 2: 17 percent / 2) NH4OAc, 25percent aq. TiCl3 / 1) MeOH; 2) H2O, MeOH 3: 96 percent / hydrogen fluoride, pyridine / acetonitrile / 1 h / Ambient temperature 4: 84 percent / 5N NaOH / methanol / 6 h / 20 - 40 °C View Scheme

1: 1) triphenylphosphine; 2) 25percent aq. TiCl3, NH4OAc / 1) THF, rt., 15 min; 2) THF-water-MeOH, rt., 5 h 2: 92 percent / hydrogen fluoride-pyridine / acetonitrile / 1.5 h / Ambient temperature 3: 89 percent / porcine liver esterase, phosphate buffer solution (pH=8) / acetone; H2O / 20 h / Ambient temperature View Scheme