1: 94 percent / pyridine / benzene / 1) 0 deg C, 1 h, 2) room temperature, 2 h 2: 91 percent / 3 h / Heating 3: 90 percent / NaH / tetrahydrofuran / 4 h / Heating View Scheme

1: KOH / methanol 2: H2 / Raney-Ni 3: polyphosphoric acid 4: sulfur / 220 °C View Scheme

T=110°C;