1: 60 percent / potassium tert-butoxide / toluene; 2-methyl-propan-2-ol / 90 °C 2: 14 percent / HCl / ethyl acetate / 12.5 h / 20 °C 3: SOCl2; DMF / tetrahydrofuran / 20 °C 4: Et3N / tetrahydrofuran; dimethylformamide / 20 °C 5: 50 percent / aq. K2CO3; Pd(PPh3)4 / toluene; ethanol / Heating View Scheme