sodium hydroxide T=100°C; 5 h;

in dimethyl sulfoxide T=170°C; 14 h;

1: 70 percent / H2S, NEt3, pyridine / 0.5 h / Ambient temperature 2: 75 percent / 2N NaOH / dimethylformamide / 0.5 h / Ambient temperature 3: 46 percent / dimethylsulfoxide / 14 h / 170 °C View Scheme

1: 75 percent / 2N NaOH / dimethylformamide / 0.5 h / Ambient temperature 2: 46 percent / dimethylsulfoxide / 14 h / 170 °C View Scheme

1: 82 percent / 0.5 h / 50 °C 2: 81 percent / 2N NaOH / 5 h / 100 °C View Scheme