1: acetic anhydride; acetic acid; hydrogenchloride / 48 h / 0 - 4 °C 2: N,N-dimethyl-formamide / 15 h / |Inert atmosphere View Scheme

hydrogenchloride; 3 A molecular sieve; acetyl chloride; silver carbonate 1.) 0 deg C, 5 h, 2.) CH3CN, 24 h, RT; Yield given. Multistep reaction;

trimethylsilyl trifluoromethanesulfonate in 1,2-dichloro-ethane T=50°C; 6 h;

trimethylsilyl trifluoromethanesulfonate in acetonitrile T=2°C; 6 h;

hydrogen bromide; acetic anhydride; acetic acid T=20°C; 1.5 h; Title compound not separated from byproducts.;

1: 90 percent / conc. HCl, AcCl / CH2Cl2 / 72 h 2: 87 percent / Ag2CO3 / acetone; H2O / 72 h View Scheme

1: 90 percent / conc. HCl, AcCl / CH2Cl2 / 72 h 2: 87 percent / Ag2CO3 / acetone; H2O / 72 h 3: 62 percent / Et3N / acetonitrile / -43 deg C -> room temperature 4: Et3N, t-BuOOH / acetonitrile / 1 h / Ambient temperature 5: iPr2NH, (Ph3P)4Pd / acetonitrile / 0.5 h 6: NaOMe / methanol / 0.5 h 7: aq. NaOH / 0.17 h View Scheme

1: HCl(g) / acetonitrile / 20 h / -42 - 20 °C 2: 1,8-diazabicyclo<5.4.0>undec-7-ene / benzene / Ambient temperature 3: BF3*Et2O / benzene; methanol / 18 h / Ambient temperature 4: 50percent aq. AcOH / ethyl acetate / Ambient temperature 5: 87 percent / diphenylphosphoryl azide, 1,8-diazabicyclo<5.4.0>undec-7-ene / 23 h / Ambient temperature 6: 78 percent / H2S, pyridine / 1.5 h / Ambient temperature 7: diisopropylethylamine / dimethylformamide / 96 h / Ambient temperature 8: aq. NaOH / methanol / Ambient temperature View Scheme

1: HCl(g) / acetonitrile / 20 h / -42 - 20 °C 2: 1,8-diazabicyclo<5.4.0>undec-7-ene / benzene / Ambient temperature 3: BF3*Et2O / benzene; methanol / 18 h / Ambient temperature 4: 50percent aq. AcOH / ethyl acetate / Ambient temperature 5: 87 percent / diphenylphosphoryl azide, 1,8-diazabicyclo<5.4.0>undec-7-ene / 23 h / Ambient temperature View Scheme

1: HCl(g) / acetonitrile / 20 h / -42 - 20 °C 2: 1,8-diazabicyclo<5.4.0>undec-7-ene / benzene / Ambient temperature 3: BF3*Et2O / benzene; methanol / 18 h / Ambient temperature 4: 50percent aq. AcOH / ethyl acetate / Ambient temperature 5: 87 percent / diphenylphosphoryl azide, 1,8-diazabicyclo<5.4.0>undec-7-ene / 23 h / Ambient temperature 6: 78 percent / H2S, pyridine / 1.5 h / Ambient temperature View Scheme