1: 1.) HF; 2.) 2-methoxypropene / 2.) pyridinium p-toluenesulfonate / 1.) H2O, MeCN, r.t., 1.75 h; 2.) CH2Cl2, 0 deg C, 40 min 2: 1.) (COCl)2; 2.Et3N / 1.) DMSO, CH2Cl2, -78 deg C, 15 min; 2.) -78 deg C, 5 min 3: 80 percent / L-Selectride / tetrahydrofuran / -78 deg C, 1 h; -43 deg C, 12 h 4: 99 percent / Et3N / DMAP / CH2Cl2 / 68 h / Ambient temperature 5: 92 percent / Bu4NF / tetrahydrofuran / 1.75 h / Ambient temperature 6: 1.) (COCl)2; 2.) Et3N / 1.) DMSO,CH2Cl2, -78 deg C, 20 min; 2.) -78 deg C, 10 min, -78 deg C -> r.t., 30 min 7: 88 percent / 1.3N HCl / tetrahydrofuran / 2 h / Ambient temperature 8: 61 percent / Ag2CO3/Celite / toluene / 2 h / 95 °C View Scheme