1: 70percent m-CPBA / CH2Cl2 / 1 h / Ambient temperature 2: BF3*Et2O, MeOH / 0.5 h / 0 °C 3: 1.) t-BuLi, 2-thienyl(cyano)copper lithium / 1.) pentane, Et2O, -78 deg C, 30 min; THF, -78 deg C, 30 min, 2.) -78 deg C, 1 h 4: 93 percent / HF*pyridine, pyridine / acetonitrile / 4 h / Ambient temperature View Scheme