in N,N-dimethyl-formamide 15 h; Inert atmosphere;

1,8-diazabicyclo[5.4.0]undec-7-ene in benzene Ambient temperature; Yield given;

silver trifluoromethanesulfonate in dichloromethane T=20°C;

silver carbonate in water; acetone 72 h;

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

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

1: 1,8-diazabicyclo<5.4.0>undec-7-ene / benzene / Ambient temperature 2: BF3*Et2O / benzene; methanol / 18 h / Ambient temperature 3: 50percent aq. AcOH / ethyl acetate / Ambient temperature 4: 87 percent / diphenylphosphoryl azide, 1,8-diazabicyclo<5.4.0>undec-7-ene / 23 h / Ambient temperature View Scheme

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

1: 1,8-diazabicyclo<5.4.0>undec-7-ene / benzene / Ambient temperature 2: BF3*Et2O / benzene; methanol / 18 h / Ambient temperature View Scheme