1: hydrogene / Pd-C / aq. NaOH 2: dioxane / 24 h 3: 72 percent / N-ethylmorpholine, isobutyl chloroformate / tetrahydrofuran / -15 - 20 °C 4: 6.2N HCl / dioxane / 1 h View Scheme

1: 72 percent / N-ethylmorpholine, isobutyl chloroformate / tetrahydrofuran / -15 - 20 °C 2: 6.2N HCl / dioxane / 1 h View Scheme

1: 1.) 5.6N HBr/AcOH, 2.) N-ethyl-morpholine / 1.) 5min, 2.) DMF 2: 72 percent / N-ethylmorpholine, isobutyl chloroformate / tetrahydrofuran / -15 - 20 °C 3: 6.2N HCl / dioxane / 1 h View Scheme

1: 74 percent / HCl(g) / diethyl ether; tetrahydrofuran / 0.25 h / 5 °C 2: 1.) 5.6N HBr/AcOH, 2.) N-ethyl-morpholine / 1.) 5min, 2.) DMF 3: 72 percent / N-ethylmorpholine, isobutyl chloroformate / tetrahydrofuran / -15 - 20 °C 4: 6.2N HCl / dioxane / 1 h View Scheme

1: 71 percent / 24 h / Ambient temperature 2: 69 percent / 1N NaOH / dioxane / 24 h / Ambient temperature 3: N-ethylmorpholine, isobutylchloroformate / tetrahydrofuran / -15 - 20 °C 4: 1.) 5.6N HBr/AcOH, 2.) Dowex 1x8 (AcO(1-) form) / 1.) room temperature, 1h, 2.) to the negative reaction for Br(1-) ions View Scheme

1: dioxane / 24 h 2: 72 percent / N-ethylmorpholine, isobutyl chloroformate / tetrahydrofuran / -15 - 20 °C 3: 6.2N HCl / dioxane / 1 h View Scheme

1: 72 percent / N-ethylmorpholine, isobutyl chloroformate / tetrahydrofuran / -15 - 20 °C 2: 6.2N HCl / dioxane / 1 h View Scheme

1: 69 percent / 1N NaOH / dioxane / 24 h / Ambient temperature 2: N-ethylmorpholine, isobutylchloroformate / tetrahydrofuran / -15 - 20 °C 3: 1.) 5.6N HBr/AcOH, 2.) Dowex 1x8 (AcO(1-) form) / 1.) room temperature, 1h, 2.) to the negative reaction for Br(1-) ions View Scheme

1: N-ethylmorpholine, isobutylchloroformate / tetrahydrofuran / -15 - 20 °C 2: 1.) 5.6N HBr/AcOH, 2.) Dowex 1x8 (AcO(1-) form) / 1.) room temperature, 1h, 2.) to the negative reaction for Br(1-) ions View Scheme