trifluoroacetic acid in dichloromethane T=0 - 20°C;

iodine; sodium hydrogencarbonate in water T=5 - 10°C; 12 h;

caesium carbonate in N,N-dimethyl-formamide T=20°C; 52 h;

1.1: t-BuLi / pentane; diethyl ether / 3 h / -20 °C 1.2: 86 percent / 1,2-diiodoethane / pentane; diethyl ether / 16 h / -78 - 20 °C 2.1: 89 percent / CF3COOH / CH2Cl2 / 2 h / 20 °C View Scheme

1: With pyridine; trifluorormethanesulfonic acid; tetra-n-butylammonium tetrafluoroborate in acetonitrile T=25°C; Electrochemical reaction; 2: With piperidine in acetonitrile T=80°C; 12 h; Electrochemical reaction; Overall yield = 97 percent;

dihydrogen peroxide; nitric acid; potassium iodide in water; acetonitrile T=24.84°C; P=760.051 Torr; pH=Ca. 4; 4 h;

iron; ammonium chloride in methanol; water T=50°C;

1.1: aq. KOH; diazotized sulfanilic acid / 0.5 h 1.2: sodium hydrosulfite / H2O / 0.25 h / 45 °C 2.1: Cs2CO3 / dimethylformamide / 48 h / 20 °C View Scheme

1: 81 percent / pyridine / 1 h / 80 °C 2: 54 percent / tri-2-furylphosphine; CuI; Pd2(dba)3 / Bu4NCl / dimethylformamide / 2 h / 20 °C 3: TBAF; AcOH / tetrahydrofuran / 5 h / 20 °C 4: IBX / ethyl acetate / 2 h / 80 °C 5: 28.4 mg / 2-methyl-2-butene; NaH2PO4*H2O; NaClO2 / 2-methyl-propan-2-ol; tetrahydrofuran; H2O / 0.5 h / 20 °C View Scheme

1.1: 96 percent / 4-dimethylaminopyridine; pyridine / 14 h / 20 °C 2.1: 82 percent / triphenylphosphine; diisopropyl azodicarboxylate / tetrahydrofuran / 0 - 20 °C 3.1: tristrimethylsilylsilane; azoisobutyronitrile / toluene / 12 h / Heating 3.2: 74 percent / p-toluenesulfonic acid / toluene / 2 h / Heating 4.1: 85 percent / hydrazine monohydrate / ethanol / 3 h / Heating 5.1: 84 percent / KOH / methanol / 9 h / Heating View Scheme