toluene-4-sulfonic acid T=120°C; 3 h;

2: 54 percent / thiourea / methanol / 24 h / Heating 3: 22 percent / aq. HCl / 10 h / Heating View Scheme

sodium hydride in N,N-dimethyl-formamide 15 h; Ambient temperature;

1: 59 percent / sodium hydride / dimethylformamide / 15 h / Ambient temperature 2: 65 percent / 10percent sulfuric acid / 3 h / Ambient temperature 3: 50 percent / lead tetraacetate / benzene / 0.5 h View Scheme