1: 54 percent / conc. HCl / methanol / 3 h / Heating 3: 72 percent / n-BuLi / tetrahydrofuran; hexane / 7 h / -78 - 20 °C 4: 88 percent / NaI, trimethylsilyl chloride / acetonitrile / 3 h / Ambient temperature View Scheme

With  hydrogenchloride in  methanol 3 h;  Heating;