zirconium tetrachloride in dichloromethane 0.25 h; Ambient temperature;

n-butyllithium in tetrahydrofuran; hexane 1.) -78 deg C, 15 min, 2.) -78 deg C, 30 min;

1: 89 percent / aq. Oxone / methanol / 1.) 5 deg C, 1 h, 2.) r.t., 3 h 2: 83 percent / BuLi / hexane; tetrahydrofuran / 1.) -78 deg C, 15 min, 2.) -78 deg C, 30 min View Scheme

1: 83 percent / t-potassium butoxide / dimethylformamide / 1.) r.t., 1 h, 2.) 3 h 2: 89 percent / aq. Oxone / methanol / 1.) 5 deg C, 1 h, 2.) r.t., 3 h 3: 83 percent / BuLi / hexane; tetrahydrofuran / 1.) -78 deg C, 15 min, 2.) -78 deg C, 30 min View Scheme

toluene-4-sulfonic acid in methanol 2 h; Heating;