1: lithium hexamethyldisilazane (LiHMDS) / tetrahydrofuran; hexamethylphosphoric acid triamide / 1 h / -78 - 0 °C 2: NaHCO3 / tetrahydrofuran; hexamethylphosphoric acid triamide / 1 h / Ambient temperature 3: 74 percent / tetra-n-butylammonium fluoride / tetrahydrofuran / Ambient temperature 4: 95 percent / LiOH / 1,2-dimethoxy-ethane; H2O / Ambient temperature View Scheme

Multi-step reaction with 2 steps 1: 91 percent / Na2CO3, Pb(OAc)4 / CH2Cl2 / 0.25 h / -78 °C2: 55 percent / toluene / 3 h / 80 °C