1: 67 percent / Lawesson's reagent / benzene; 1,2-dimethoxy-ethane / 1 h / Heating 2: 41 percent / chloranil / toluene / 20 h / Heating View Scheme

trimethylsilyl bromide in dichloromethane T=20°C; 53 h;

potassium hydroxide in ethanol cyclocondensation; 6 h; Heating;