1: 77 percent / NH2OH*HCl, pyridine / ethanol / 24 h / Heating 2: 64 percent / NaOH / H2O / 21 h / Heating 3: 1.) CDI / 1.) THF, r.t., 1 h, 2.) THF, light petroleum, 0-5 deg C, 4 h 4: 5 percent / various solvent(s) / 1 h / Heating View Scheme