1: 1) NaOH, 2) acetic anhydride / 1) H2O, MeOH, reflux, 7 h, 2) 100 deg C, 3 h 2: 88 percent / aq. ammonia / 1) 6 h, RT, 2) toluene, 15 h, reflux 3: 440 mg / NaBH4, 2M HCl / tetrahydrofuran; ethanol 4: 95 percent / triethylsilane / trifluoroacetic acid / 0.5 h 5: 72 percent / toluene-p-sulphonic acid / CH2Cl2 / 15 h / Ambient temperature 6: 54 percent / triphenylphosphine / various solvent(s) / 40 h / Heating 7: 80 percent / 2M H2SO4 / tetrahydrofuran / 2 h / 50 °C View Scheme