sodium hydride in tetrahydrofuran 8 h; Heating;

1: 1.) POCl3; 2.) 2.5N NaOH / 1.) iPAc, DMF 2: 94 percent / MeSO3H / various solvent(s) 3: LHMDS, HMPA / tetrahydrofuran / 1.) -78 deg C, 2h; 2.) warmed to -10 deg C 4: 74 percent / 12N HCl / 1 h View Scheme