(i) NaNO2, aq. HCl, (ii) SO2, CuCl2, KCl, benzene, dioxane; Multistep reaction;

1: 1.) t-BuOK, 18-crown-6 / 1.) THF, 15 min, 2.) THF, RT, 3.5 h 2: 36 percent / 2 N aq. KOH / ethanol; tetrahydrofuran / Ambient temperature 3: 51 percent / N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride, 4-dimethylaminopyridine / tetrahydrofuran / 18 h / Ambient temperature View Scheme

1: 1.) t-BuOK, 18-crown-6 / 1.) THF, 15 min, 2.) THF, RT, 3.5 h 2: 36 percent / 2 N aq. KOH / ethanol; tetrahydrofuran / Ambient temperature View Scheme

18-crown-6 ether; potassium tert-butylate 1.) THF, 15 min, 2.) THF, RT, 3.5 h; Yield given. Multistep reaction;

ammonium hydroxide in acetonitrile T=0 - 20°C; 1 h; Inert atmosphere;

sodium hydroxide; phenylmethyltriethylammonium bromide in water; toluene T=20°C; 20 h;

in tetrahydrofuran; hexane T=-78 - 20°C;

potassium fluoride in 1,4-dioxane 24 h; Heating / reflux;