1: 55 percent / toluene / 3 h / 80 °C 2: lithium hexamethyldisilazane (LiHMDS) / tetrahydrofuran; hexamethylphosphoric acid triamide / 1 h / -78 - 0 °C 3: NaHCO3 / tetrahydrofuran; hexamethylphosphoric acid triamide / 1 h / Ambient temperature 4: 74 percent / tetra-n-butylammonium fluoride / tetrahydrofuran / Ambient temperature 5: 95 percent / LiOH / 1,2-dimethoxy-ethane; H2O / Ambient temperature View Scheme

With  lead(IV) acetate; sodium carbonate in  dichloromethane T=-78°C; 0.25 h;