1: 1.) s-BuLi, TMEDA / 1.) cyclohexane, THF, -78 deg C, 1 h, 2.) THF, cyclohexane, from -78 deg C to RT, 8 h 3: 95 percent / TBAF / tetrahydrofuran / 0.08 h / Ambient temperature 4: 50 percent / heptafluorobutyric acid / 36 h / Heating View Scheme

1: 1.) s-BuLi, TMEDA / 1.) cyclohexane, THF, -78 deg C, 1 h, 2.) THF, cyclohexane, from -78 deg C to RT, 8 h 2: 1.) s-BuLi, TMEDA / 1.) cyclohexane, THF, -78 deg C, 1 h, 2.) THF, cyclohexane, from -78 deg C to RT, 8 h 3: 83 percent / CsF / dimethylformamide; H2O / Heating View Scheme