thionyl chloride 3 h; Heating;

1: 100 percent / KOH / tetrahydrofuran; methanol / 5 h / 20 °C 2: SOCl2 / 2 h / Heating View Scheme

1: 70 percent / methanol / Heating 2: 65 percent / PPA / 120 °C 3: 92 percent / Ph3P; diisopropyl azodicarboxylate / tetrahydrofuran / 2.5 h / 0 - 20 °C 4: 100 percent / KOH / tetrahydrofuran; methanol / 20 h / 20 °C 5: SOCl2 / 1 h / Heating View Scheme

in dichloromethane T=20°C; 4 h;