2: 89 percent / Et3N, DMAP, DCC / CH2Cl2 / 24 h / 0 - 20 °C 3: 84 percent / 0.5N NaOH / acetone; H2O / 24 h / Ambient temperature 4: 84 percent / Et3N, isobutyl chlorocarbonate / dimethylformamide; tetrahydrofuran / -18 - 25 °C 5: hydrazine hydrate / methanol / Heating 6: 98 percent / 25percent HBr/AcOH / 2 h View Scheme

1: 89 percent / Et3N, DMAP, DCC / CH2Cl2 / 24 h / 0 - 20 °C 2: 84 percent / 0.5N NaOH / acetone; H2O / 24 h / Ambient temperature 3: 84 percent / Et3N, isobutyl chlorocarbonate / dimethylformamide; tetrahydrofuran / -18 - 25 °C 4: hydrazine hydrate / methanol / Heating 5: 98 percent / 25percent HBr/AcOH / 2 h View Scheme

1: 89 percent / Et3N, DMAP, DCC / CH2Cl2 / 24 h / 0 - 20 °C 2: 84 percent / 0.5N NaOH / acetone; H2O / 24 h / Ambient temperature 3: 84 percent / Et3N, isobutyl chlorocarbonate / dimethylformamide; tetrahydrofuran / -18 - 25 °C 4: hydrazine hydrate / methanol / Heating 5: 98 percent / 25percent HBr/AcOH / 2 h View Scheme

1: 84 percent / 0.5N NaOH / acetone; H2O / 24 h / Ambient temperature 2: 84 percent / Et3N, isobutyl chlorocarbonate / dimethylformamide; tetrahydrofuran / -18 - 25 °C 3: hydrazine hydrate / methanol / Heating 4: 98 percent / 25percent HBr/AcOH / 2 h View Scheme

hydrogen bromide; acetic acid 2 h;

1: 84 percent / Et3N, isobutyl chlorocarbonate / dimethylformamide; tetrahydrofuran / -18 - 25 °C 2: hydrazine hydrate / methanol / Heating 3: 98 percent / 25percent HBr/AcOH / 2 h View Scheme

1: 84 percent / Et3N, isobutyl chlorocarbonate / dimethylformamide; tetrahydrofuran / -18 - 25 °C 2: hydrazine hydrate / methanol / Heating 3: 98 percent / 25percent HBr/AcOH / 2 h View Scheme

1: hydrazine hydrate / methanol / Heating 2: 98 percent / 25percent HBr/AcOH / 2 h View Scheme