1: 93.5 percent / conc. H2SO4 / 1 h / Heating 2: 99 percent / HCl gas / tetrahydrofuran; ethyl acetate / 29 h / Ambient temperature 3: 87 percent / aq. NaOH / methanol / 18 h / Ambient temperature 4: p-toluenesulfonic acid / pyridine / 16 h / Ambient temperature 5: aq. oxalic acid / methanol / 1 h / Heating 6: sodium hydride / dimethylformamide / 42 h / Ambient temperature 7: methanol / 18 h / Ambient temperature View Scheme

1: p-toluenesulfonic acid / pyridine / 16 h / Ambient temperature 2: aq. oxalic acid / methanol / 1 h / Heating 3: sodium hydride / dimethylformamide / 42 h / Ambient temperature 4: methanol / 18 h / Ambient temperature View Scheme

1: 99 percent / HCl gas / tetrahydrofuran; ethyl acetate / 29 h / Ambient temperature 2: 87 percent / aq. NaOH / methanol / 18 h / Ambient temperature 3: p-toluenesulfonic acid / pyridine / 16 h / Ambient temperature 4: aq. oxalic acid / methanol / 1 h / Heating 5: sodium hydride / dimethylformamide / 42 h / Ambient temperature 6: methanol / 18 h / Ambient temperature View Scheme

1: p-toluenesulfonic acid / pyridine / 16 h / Ambient temperature 2: aq. oxalic acid / methanol / 1 h / Heating 3: sodium hydride / dimethylformamide / 42 h / Ambient temperature 4: methanol / 18 h / Ambient temperature View Scheme

in methanol 18 h; Ambient temperature;