sodium nitrite in acetic acid 1.) 0-5 deg C, 20 min; 2.) RT, 1 h;

1: 74 percent 2: 78 percent / Br2 / ethanol / 0.5 h / Ambient temperature 3: 91 percent / hydrazine hydrate / ethanol / 0.5 h / Ambient temperature 4: 90 percent / sodium nitrite (NaNO2) / acetic acid / 1.) 0-5 deg C, 20 min; 2.) RT, 1 h View Scheme

1: 78 percent / Br2 / ethanol / 0.5 h / Ambient temperature 2: 91 percent / hydrazine hydrate / ethanol / 0.5 h / Ambient temperature 3: 90 percent / sodium nitrite (NaNO2) / acetic acid / 1.) 0-5 deg C, 20 min; 2.) RT, 1 h View Scheme

1: 91 percent / hydrazine hydrate / ethanol / 0.5 h / Ambient temperature 2: 90 percent / sodium nitrite (NaNO2) / acetic acid / 1.) 0-5 deg C, 20 min; 2.) RT, 1 h View Scheme

1: 74 percent 2: 78 percent / Br2 / ethanol / 0.5 h / Ambient temperature 3: 91 percent / hydrazine hydrate / ethanol / 0.5 h / Ambient temperature 4: 90 percent / sodium nitrite (NaNO2) / acetic acid / 1.) 0-5 deg C, 20 min; 2.) RT, 1 h View Scheme