1: 85 percent / pyridine / 48 h / 60 - 65 °C 2: 88 percent / pyridine / 5 °C 3: 65 percent / 1,8-diazabicyclo<5.4.0>undec-7-ene (DBU) / 1 h / 110 - 120 °C 4: 80percent AcOH / 0.17 h View Scheme

1: 92 percent / 3-methylbutylnitrite / acetic acid; H2O / 48 h / Ambient temperature 2: 84 percent / dimethylaminopyridine / stirred overnight 3: 90 percent / thionyl chloride, DMF / CHCl3 / 4 h / Heating 4: 75 percent / hydrxylamine hydrochloride, sodium methoxide / methanol / 1)room temp., overnight 2)autoclave, 120 deg C, 7h View Scheme

1: 80.9 percent / Br2 / H2O / Ambient temperature 2: 86 percent / ethyl orthoformate / aq. HCl; dimethylformamide / 2 h / Ambient temperature View Scheme

1: 80.9 percent / Br2 / H2O / Ambient temperature 2: 86 percent / ethyl orthoformate / aq. HCl; dimethylformamide / 2 h / Ambient temperature 3: 1) NaH / 1) DMF, 40 deg C, 30 min, 2) 100 deg C, 9 h 4: 82 percent / H2SO4 / H2O / 48 h / Ambient temperature View Scheme

Multi-step reaction with 3 steps 1: 92 percent / 3-methylbutylnitrite / acetic acid; H2O / 48 h / Ambient temperature2: 84 percent / dimethylaminopyridine / stirred overnight3: 90 percent / thionyl chloride, DMF / CHCl3 / 4 h / Heating