NOBF4; 1-n-butyl-3-methylimidazolium tetrafluoroborate T=0°C; Schiemann reaction; 168 h; UV-irradiation;

1: 2.6 g / CHCl3; ethanol / 2.5 h / Heating 2: 1.) sodium nitrite, 50percent aq. tetrafluoroboric acid / 1.) water, 2.) irradiation, 72 h View Scheme

1: 1.) aluminium amalgam / 1.) ether, water, 0.5 h, 2.) ethanol, 4 deg C, 1 h 2: 2.6 g / CHCl3; ethanol / 2.5 h / Heating 3: 1.) sodium nitrite, 50percent aq. tetrafluoroboric acid / 1.) water, 2.) irradiation, 72 h View Scheme

tetrafluoroboric acid; sodium nitrite 1.) water, -25 deg C, 10 min, 2.) irradiation, 72 h; Yield given. Multistep reaction;

lithium aluminium tetrahydride in diethyl ether

1: 1) aq.NaNO2 / 1) 2N HCl (ice-cold) 2) 10percent Na2CO3 (ice-cold) 2: 65.5 percent / formamidinesulfinic acid (FASA) / NEt3 / methanol; H2O / 20 h / 45 - 50 °C View Scheme

1: 1) aq.NaNO2 / 1) 2N HCl (ice-cold) 2) 10percent Na2CO3 (ice-cold) 2: 65.5 percent / formamidinesulfinic acid (FASA) / NEt3 / methanol; H2O / 20 h / 45 - 50 °C 3: 53 percent / 50percent HBF4 / aq.NaNO2 / 3 h / -60 - -40 °C / Irradiation View Scheme

triethylamine in dichloromethane Ambient temperature;

1: 5-fluoro-1H-imidazole-4-carboxylic acid ethyl ester With N-ethyl-N,N-diisopropylamine T=-12°C; 0.25 h; 2: chloromethyl methyl ether T=-12 - 20°C;

1: 1) aq.NaNO2 / 1) 2N HCl (ice-cold) 2) 10percent Na2CO3 (ice-cold) 2: 65.5 percent / formamidinesulfinic acid (FASA) / NEt3 / methanol; H2O / 20 h / 45 - 50 °C 3: 53 percent / 50percent HBF4 / aq.NaNO2 / 3 h / -60 - -40 °C / Irradiation 4: 81 percent / NEt3 / CH2Cl2 / 2 h / Ambient temperature 5: NaBH4 / propan-1-ol / Ambient temperature View Scheme