1: 71 percent / dicyclohexylcarbodiimide (DCC), 1-hydroxybenzotriazole (HOBt) / dimethylformamide / -10 °C 2: TFA, anisole / 0.75 h / 0 - 20 °C 3: 1.) HCl/dioxane, isoamyl nitrite / 1.) DMF, -10 deg C, 10 min, 2.) DMF, overnight 4: H2, AcOH / Pd / methanol / 12 h View Scheme

hydrogen; acetic acid; palladium in methanol 12 h;

1: 1.) HCl/dioxane, isoamyl nitrite / 1.) DMF, -10 deg C, 10 min, 2.) DMF, overnight 2: H2, AcOH / Pd / methanol / 12 h View Scheme

1: 71 percent / dicyclohexylcarbodiimide (DCC), 1-hydroxybenzotriazole (HOBt) / dimethylformamide / -10 °C 2: TFA, anisole / 0.75 h / 0 - 20 °C 3: 1.) HCl/dioxane, isoamyl nitrite / 1.) DMF, -10 deg C, 10 min, 2.) DMF, overnight 4: H2, AcOH / Pd / methanol / 12 h View Scheme

1: 80.4 percent / hydrazine hydrate / ethanol / Ambient temperature 2: 1.) HCl/dioxane, isoamyl nitrite / 1.) DMF, -10 deg C, 10 min, 2.) DMF, overnight 3: H2, AcOH / Pd / methanol / 12 h View Scheme

1: 1.) HCl/dioxane, isoamyl nitrite / 1.) DMF, -10 deg C, 10 min, 2.) DMF, overnight 2: H2, AcOH / Pd / methanol / 12 h View Scheme

1: TFA, anisole / 0.75 h / 0 - 20 °C 2: 1.) HCl/dioxane, isoamyl nitrite / 1.) DMF, -10 deg C, 10 min, 2.) DMF, overnight 3: H2, AcOH / Pd / methanol / 12 h View Scheme

1.1: NMM; isobutyl chloroformate / acetonitrile / 0.17 h / -15 °C 1.2: 1-hydroxybenzotriazole hydrate / acetonitrile / 0.17 h / cooling 1.3: 90.5 percent / NMM / acetonitrile; dimethylformamide / 20 °C / pH 8 2.1: HCl / dioxane / 1.5 h 3.1: 89.6 percent / NMM; isobutyl chloroformate / dimethylformamide; acetonitrile 4.1: HCl / dioxane / 1.5 h 5.1: 90.1 percent / NMM; isobutyl chloroformate / acetonitrile 6.1: ammonium formate / palladium on carbon / methanol / 0.5 h / 20 °C 7.1: trifluoroacetic acid View Scheme

1.1: NMM; isobutyl chloroformate / acetonitrile / 0.17 h / -15 °C 1.2: 1-hydroxybenzotriazole hydrate / acetonitrile / 0.17 h / cooling 1.3: 90.5 percent / NMM / acetonitrile; dimethylformamide / 20 °C / pH 8 2.1: HCl / dioxane / 1.5 h 3.1: 89.6 percent / NMM; isobutyl chloroformate / dimethylformamide; acetonitrile 4.1: HCl / dioxane / 1.5 h 5.1: 90.1 percent / NMM; isobutyl chloroformate / acetonitrile 6.1: ammonium formate / palladium on carbon / methanol / 0.5 h / 20 °C 7.1: trifluoroacetic acid View Scheme

1: HCl / dioxane / 1.5 h 2: 89.6 percent / NMM; isobutyl chloroformate / dimethylformamide; acetonitrile 3: HCl / dioxane / 1.5 h 4: 90.1 percent / NMM; isobutyl chloroformate / acetonitrile 5: ammonium formate / palladium on carbon / methanol / 0.5 h / 20 °C 6: trifluoroacetic acid View Scheme