1: 85 percent / pyridine; ethanol / 22 h / Ambient temperature 2: 80 percent / KOH / methanol; H2O / 18 h / Heating 3: 86.2 percent / triethylamine / CH2Cl2 / 0.5 h / cooling 4: 90.6 g / dimethylformamide / 3 h / 70 °C 5: NaOH / methanol; H2O / 72 h / Heating 6: 63.3 percent / 2N HCl / acetone / 5 h / Heating 7: 87.3 percent / p-toluenesulfonic acid / 17 h / Heating View Scheme

1: 85 percent / pyridine; ethanol / 22 h / Ambient temperature 2: 80 percent / KOH / methanol; H2O / 18 h / Heating 3: 86.2 percent / triethylamine / CH2Cl2 / 0.5 h / cooling 4: 1) 57percent NaH / 1) 1h, DME; 2) DME, 16h, reflux 5: KOH / methanol; H2O / 18 h / Heating 6: various solvent(s) / Heating 7: 2N HCl / acetone / 5 h / Heating View Scheme