T=240°C; 5 h;

1: aq. HCl / tetrahydrofuran / 0.67 h 2: 1.) 4-dimethylaminopyridine, 2.) 88percent aq. HCOOH / 1.) THF, 1 h, 25 deg C, 2.) 30 min 3: 1.) DMF, 2 h, 25 deg C, 2.) ether, 16 h, 5 deg C 4: KOH / methanol / 1 h / 25 °C View Scheme

hydrogenchloride in tetrahydrofuran 0.666667 h; Yield given;