1: N-bromosuccinimide, 2,2'-azo-bis-(isobutyronitril) / CCl4 2: 97 percent / aq. N-benzyl-tri-n-butylammonium-chloride / CH2Cl2 / 43 h / 20 °C 3: aq. HCl / 1.5 h / 20 - 23 °C 4: aq. NaNO2, aq. HCl / 2 h / 35 °C View Scheme

1: With n-butyllithium; diisopropylamine in tetrahydrofuran; hexane T=-30°C; 0.5 h; 2: ethyl 2-ethoxy-4-methyl-benzoate With N,N,N',N',N'',N''-hexamethylphosphoric triamide in tetrahydrofuran; hexane T=-75°C; 2 h; 3: carbon dioxide in tetrahydrofuran; hexane T=-75 - 10°C; 0.5 h;

1: N-bromosuccinimide, 2,2'-azo-bis-(isobutyronitril) / CCl4 2: 97 percent / aq. N-benzyl-tri-n-butylammonium-chloride / CH2Cl2 / 43 h / 20 °C 3: HCl / Heating 4: 59 percent / NaOH / ethanol / 1.5 h / 23 - 25 °C View Scheme

1: N-bromosuccinimide, 2,2'-azo-bis-(isobutyronitril) / CCl4 2: 97 percent / aq. N-benzyl-tri-n-butylammonium-chloride / CH2Cl2 / 43 h / 20 °C 3: HCl / Heating 4: 59 percent / NaOH / ethanol / 1.5 h / 23 - 25 °C 5: 29 percent / PPh3, Et3N, CCl4 / acetonitrile / 15 h / Ambient temperature 6: 92 percent / 1N NaOH / ethanol / 4 h / 60 °C View Scheme

1: N-bromosuccinimide, 2,2'-azo-bis-(isobutyronitril) / CCl4 2: 97 percent / aq. N-benzyl-tri-n-butylammonium-chloride / CH2Cl2 / 43 h / 20 °C 3: HCl / Heating View Scheme

potassium carbonate in dimethyl sulfoxide T=35 - 40°C; 11 h;

potassium carbonate in toluene T=25 - 45°C; 21 - 31.5 h; Heating / reflux;

potassium carbonate in acetone T=20°C; 72 h;

ethanol

1: N-bromosuccinimide, 2,2'-azo-bis-(isobutyronitril) / CCl4 2: 97 percent / aq. N-benzyl-tri-n-butylammonium-chloride / CH2Cl2 / 43 h / 20 °C 3: HCl / Heating 4: 59 percent / NaOH / ethanol / 1.5 h / 23 - 25 °C 5: 29 percent / PPh3, Et3N, CCl4 / acetonitrile / 15 h / Ambient temperature View Scheme