1.1: HCl; sodium nitrite / H2O / 3.5 h / cooling 1.2: 60 percent / sodium azide / H2O; diethyl ether / 2 h / 0 °C 2.1: 96 percent / hydrazine hydrate / ethanol; tetrahydrofuran; H2O / 26 h / 20 °C 3.1: 33 percent / ethanol / 24 h / Heating View Scheme