selenium T=300°C; 8 h;

1: 82 percent / NaOH / aq. ethanol / r.t., 30min., then reflux, 4h 2: 78 percent / polyphosphoric acid / 1.5 h / 190 - 200 °C 3: 71 percent / Se powder / 8 h / 300 °C View Scheme

1: 82 percent / NaOH / aq. ethanol / r.t., 30min., then reflux, 4h 2: 78 percent / polyphosphoric acid / 1.5 h / 190 - 200 °C 3: 71 percent / Se powder / 8 h / 300 °C View Scheme

1: 92 percent / LiAlH4 / diethyl ether / 3 h / Heating 2: 82 percent / NaOH / aq. ethanol / r.t., 30min., then reflux, 4h 3: 78 percent / polyphosphoric acid / 1.5 h / 190 - 200 °C 4: 71 percent / Se powder / 8 h / 300 °C View Scheme

1: 1. conc. hydrochloric acid, NaNO2; / 1. 0 degC, 30min.; 2. 45 degC 2: 92 percent / LiAlH4 / diethyl ether / 3 h / Heating 3: 82 percent / NaOH / aq. ethanol / r.t., 30min., then reflux, 4h 4: 78 percent / polyphosphoric acid / 1.5 h / 190 - 200 °C 5: 71 percent / Se powder / 8 h / 300 °C View Scheme

1: 78 percent / polyphosphoric acid / 1.5 h / 190 - 200 °C 2: 71 percent / Se powder / 8 h / 300 °C View Scheme