1: 77 percent / conc. H2SO4 / 16 h / Heating 2: 92 percent / imidazole / dimethylformamide / 5 h / 35 °C 3: 1.) Al(Me)3 / 1.) CHCl3, hexane, 1 h, RT, 2.) CHCl3, hexane, 45 deg C, 4 h 4: 52 percent / (nBu)4NF / tetrahydrofuran / 4 h / Ambient temperature 5: 46 percent / Et3N, methanesulfonic anhydride / CH2Cl2; dioxane / 3 h 6: 70 percent / NH3, Li / tetrahydrofuran / -78 - -58 °C View Scheme