1: 92 percent / CH2Cl2 / 72 h / Ambient temperature 2: 57 percent / Li2CO3, LiCl / hexamethylphosphoric acid triamide / 2.5 h / 115 °C 3: 76 percent / 17α-chloro-3β-hydroxy-17β-nitroso-5α-androstane / CHCl3; methanol / 240 h / -18 °C View Scheme