1: 94 percent / pyridine / 72 h / Ambient temperature 2: 76 percent / 6 M aq. HCl / dioxane / 24 h / Heating 3: 76 percent / N-bromosuccinimide / tetrahydrofuran / 3 h / Ambient temperature View Scheme

1: 94 percent / pyridine / 72 h / Ambient temperature 2: 76 percent / 6 M aq. HCl / dioxane / 24 h / Heating 3: 76 percent / N-bromosuccinimide / tetrahydrofuran / 3 h / Ambient temperature 4: 1.) butyllithium / 1.) hexane, THF, -78 deg C, 15 min, 2.) hexane, THF, 30 min 5: 1.) (COCl)2, DMSO, 2.) Et3N / 1.) CH2Cl2, -60 deg C, 30 min, 2.) CH2Cl2, from -60 deg C to RT View Scheme